Science.gov

Sample records for adjacent water molecules

  1. 33 CFR 80.1395 - Puget Sound and adjacent waters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake...

  2. 33 CFR 80.1395 - Puget Sound and adjacent waters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake...

  3. 33 CFR 80.1395 - Puget Sound and adjacent waters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake...

  4. 33 CFR 80.1395 - Puget Sound and adjacent waters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake...

  5. 33 CFR 80.1395 - Puget Sound and adjacent waters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Puget Sound and adjacent waters... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Thirteenth District § 80.1395 Puget Sound and adjacent waters. The 72 COLREGS shall apply on all waters of Puget Sound and adjacent waters, including Lake...

  6. View from water showing south facade and adjacent boat slips ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from water showing south facade and adjacent boat slips (Facility Nos. S375 & S376) - U.S. Naval Base, Pearl Harbor, Boat House, Hornet Avenue at Independence Street, Pearl City, Honolulu County, HI

  7. 7. VIEW OF WATER TREATMENT PLANT, ADJACENT TO THE COAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW OF WATER TREATMENT PLANT, ADJACENT TO THE COAL CONVEYOR; IN THE DISTANCE IS THE FREQUENCY CHANGER HOUSE, WHICH IS ATTACHED TO SWITCH HOUSE NO. 1; LOOKING WEST. - Commonwealth Electric Company, Fisk Street Electrical Generating Station, 1111 West Cermak Avenue, Chicago, Cook County, IL

  8. How subaerial salt extrusions influence water quality in adjacent aquifers

    NASA Astrophysics Data System (ADS)

    Mehdizadeh, Razieh; Zarei, Mehdi; Raeisi, Ezzat

    2015-12-01

    Brines supplied from salt extrusions cause significant groundwater salinization in arid and semi-arid regions where salt rock is exposed to dissolution by episodic rainfalls. Here we focus on 62 of the 122 diapirs of Hormuz salt emergent in the southern Iran. To consider managing the degradation effect that salt extrusions have on the quality of adjoining aquifers, it is first necessary to understand how they influence adjacent water resources. We evaluate here the impacts that these diapirs have on adjacent aquifers based on investigating their geomorphologies, geologies, hydrologies and hydrogeologies. The results indicate that 28/62 (45%) of our sample of salt diapirs have no significant impact on the quality of groundwater in adjoining aquifers (namely Type N), while the remaining 34/62 (55%) degrade nearby groundwater quality. We offer simple conceptual models that account for how brines flowing from each of these types of salt extrusions contaminate adjacent aquifers. We identify three main mechanisms that lead to contamination: surface impact (Type A), subsurface intrusion (Type B) and indirect infiltration (Type C). A combination of all these mechanisms degrades the water quality in nearby aquifers in 19/62 (31%) of the salt diapirs studied. Having characterized the mechanism(s) by which each diapir affects the adjacent aquifer, we suggest a few possible remediation strategies to be considered. For instance, engineering the surface runoff of diapirs Types A and C into nearby evaporation basins would improve groundwater quality.

  9. 49 CFR 214.107 - Working over or adjacent to water.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... conditions, including weather, water speed, and terrain, merit additional protection, the skiff or boat shall... 49 Transportation 4 2012-10-01 2012-10-01 false Working over or adjacent to water. 214.107 Section... Working over or adjacent to water. (a) Bridge workers working over or adjacent to water with a depth...

  10. 49 CFR 214.107 - Working over or adjacent to water.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... conditions, including weather, water speed, and terrain, merit additional protection, the skiff or boat shall... 49 Transportation 4 2010-10-01 2010-10-01 false Working over or adjacent to water. 214.107 Section... Working over or adjacent to water. (a) Bridge workers working over or adjacent to water with a depth...

  11. 49 CFR 214.107 - Working over or adjacent to water.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... conditions, including weather, water speed, and terrain, merit additional protection, the skiff or boat shall... 49 Transportation 4 2011-10-01 2011-10-01 false Working over or adjacent to water. 214.107 Section... Working over or adjacent to water. (a) Bridge workers working over or adjacent to water with a depth...

  12. 49 CFR 214.107 - Working over or adjacent to water.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... conditions, including weather, water speed, and terrain, merit additional protection, the skiff or boat shall... 49 Transportation 4 2013-10-01 2013-10-01 false Working over or adjacent to water. 214.107 Section... Working over or adjacent to water. (a) Bridge workers working over or adjacent to water with a depth...

  13. 49 CFR 214.107 - Working over or adjacent to water.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... conditions, including weather, water speed, and terrain, merit additional protection, the skiff or boat shall... 49 Transportation 4 2014-10-01 2014-10-01 false Working over or adjacent to water. 214.107 Section... Working over or adjacent to water. (a) Bridge workers working over or adjacent to water with a depth...

  14. Structure and dynamics of water molecules confined in triglyceride oils.

    PubMed

    Groot, Carien C M; Velikov, Krassimir P; Bakker, Huib J

    2016-10-26

    Though it is commonly known that a small amount of water can be present in triglyceride oil, a molecular picture of how water molecules organize in the oil phase is lacking. We investigate the hydrogen-bond configuration and dynamics of water in triacetin, tributyrin and trioctanoin using linear infrared and time-resolved two-dimensional infrared (2DIR) spectroscopy of the water hydroxyl stretch vibration. We identify water molecules with a single strong hydrogen bond to the triglyceride, water molecules with two weaker hydrogen bonds to the triglycerides, and water clusters. These species do not interconvert on the 20 ps timescale of the experiment, as evidenced by the absence of cross-peaks in the 2DIR spectrum. The vibrational response of water molecules with a single strong hydrogen bond to the triglyceride depends strongly on the excitation frequency, revealing the presence of different subspecies of singly-bound water molecules that correspond to different hydrogen-bond locations. In contrast, the water molecules with two weaker hydrogen bonds to the triglyceride correspond to a single, specific hydrogen-bond configuration; these molecules likely bridge the carbonyl groups of adjacent triglyceride molecules, which can have considerable influence on liquid triglyceride properties.

  15. Water: a responsive small molecule.

    PubMed

    Shultz, Mary Jane; Vu, Tuan Hoang; Meyer, Bryce; Bisson, Patrick

    2012-01-17

    Unique among small molecules, water forms a nearly tetrahedral yet flexible hydrogen-bond network. In addition to its flexibility, this network is dynamic: bonds are formed or broken on a picosecond time scale. These unique features make probing the local structure of water challenging. Despite the challenges, there is intense interest in developing a picture of the local water structure due to water's fundamental importance in many fields of chemistry. Understanding changes in the local network structure of water near solutes likely holds the key to unlock problems from analyzing parameters that determine the three dimensional structure of proteins to modeling the fate of volatile materials released into the atmosphere. Pictures of the local structure of water are heavily influenced by what is known about the structure of ice. In hexagonal I(h) ice, the most stable form of solid water under ordinary conditions, water has an equal number of donor and acceptor bonds; a kind of symmetry. This symmetric tetrahedral coordination is only approximately preserved in the liquid. The most obvious manifestation of this altered tetrahedral bonding is the greater density in the liquid compared with the solid. Formation of an interface or addition of solutes further modifies the local bonding in water. Because the O-H stretching frequency is sensitive to the environment, vibrational spectroscopy provides an excellent probe for the hydrogen-bond structure in water. In this Account, we examine both local interactions between water and small solutes and longer range interactions at the aqueous surface. Locally, the results suggest that water is not a symmetric donor or acceptor, but rather has a propensity to act as an acceptor. In interactions with hydrocarbons, action is centered at the water oxygen. For soluble inorganic salts, interaction is greater with the cation than the anion. The vibrational spectrum of the surface of salt solutions is altered compared with that of neat

  16. Water molecules orientation in surface layer

    NASA Astrophysics Data System (ADS)

    Klingo, V. V.

    2000-08-01

    The water molecules orientation has been investigated theoretically in the water surface layer. The surface molecule orientation is determined by the direction of a molecule dipole moment in relation to outward normal to the water surface. Entropy expressions of the superficial molecules in statistical meaning and from thermodynamical approach to a liquid surface tension have been found. The molecules share directed opposite to the outward normal that is hydrogen protons inside is equal 51.6%. 48.4% water molecules are directed along to surface outward normal that is by oxygen inside. A potential jump at the water surface layer amounts about 0.2 volts.

  17. 33 CFR 165.1303 - Puget Sound and adjacent waters, WA-regulated navigation area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Puget Sound and adjacent waters... § 165.1303 Puget Sound and adjacent waters, WA—regulated navigation area. (a) The following is a... Light to New Dungeness Light and all points in the Puget Sound area north and south of these lights....

  18. 33 CFR 165.1303 - Puget Sound and adjacent waters, WA-regulated navigation area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Puget Sound and adjacent waters... § 165.1303 Puget Sound and adjacent waters, WA—regulated navigation area. (a) The following is a... Light to New Dungeness Light and all points in the Puget Sound area north and south of these lights....

  19. 33 CFR 165.1303 - Puget Sound and adjacent waters, WA-regulated navigation area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Puget Sound and adjacent waters... § 165.1303 Puget Sound and adjacent waters, WA—regulated navigation area. (a) The following is a... Light to New Dungeness Light and all points in the Puget Sound area north and south of these lights....

  20. 33 CFR 165.1303 - Puget Sound and adjacent waters, WA-regulated navigation area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Puget Sound and adjacent waters... § 165.1303 Puget Sound and adjacent waters, WA—regulated navigation area. (a) The following is a... Light to New Dungeness Light and all points in the Puget Sound area north and south of these lights....

  1. 33 CFR 165.1303 - Puget Sound and adjacent waters, WA-regulated navigation area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Puget Sound and adjacent waters... § 165.1303 Puget Sound and adjacent waters, WA—regulated navigation area. (a) The following is a... Light to New Dungeness Light and all points in the Puget Sound area north and south of these lights....

  2. Conserved water molecules in bacterial serine hydroxymethyltransferases.

    PubMed

    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.

  3. 33 CFR 334.70 - Buzzards Bay, and adjacent waters, Mass.; danger zones for naval operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... REGULATIONS § 334.70 Buzzards Bay, and adjacent waters, Mass.; danger zones for naval operations. (a) Atlantic Ocean in vicinity of No Mans Land—(1) The area. The waters surrounding No Mans Land within an...

  4. Modelling water molecules inside cyclic peptide nanotubes

    NASA Astrophysics Data System (ADS)

    Tiangtrong, Prangsai; Thamwattana, Ngamta; Baowan, Duangkamon

    2016-03-01

    Cyclic peptide nanotubes occur during the self-assembly process of cyclic peptides. Due to the ease of synthesis and ability to control the properties of outer surface and inner diameter by manipulating the functional side chains and the number of amino acids, cyclic peptide nanotubes have attracted much interest from many research areas. A potential application of peptide nanotubes is their use as artificial transmembrane channels for transporting ions, biomolecules and waters into cells. Here, we use the Lennard-Jones potential and a continuum approach to study the interaction of a water molecule in a cyclo[(- D-Ala- L-Ala)_4-] peptide nanotube. Assuming that each unit of a nanotube comprises an inner and an outer tube and that a water molecule is made up of a sphere of two hydrogen atoms uniformly distributed over its surface and a single oxygen atom at the centre, we determine analytically the interaction energy of the water molecule and the peptide nanotube. Using this energy, we find that, independent of the number of peptide units, the water molecule will be accepted inside the nanotube. Once inside the nanotube, we show that a water molecule prefers to be off-axis, closer to the surface of the inner nanotube. Furthermore, our study of two water molecules inside the peptide nanotube supports the finding that water molecules form an array of a 1-2-1-2 file inside peptide nanotubes. The theoretical study presented here can facilitate thorough understanding of the behaviour of water molecules inside peptide nanotubes for applications, such as artificial transmembrane channels.

  5. Water resources of Okaloosa County and adjacent areas, Florida

    USGS Publications Warehouse

    Trapp, Henry; Pascale, C.A.; Foster, J.B.

    1977-01-01

    Okaloosa County, in the northwest Florida panhandle, uses the Floridan aquifer for water supply, although it also has abundant surface water and ground water in the surficial sand-and-gravel aquifer. Water levels have declined locally more than 90 feet in the upper limestone of the Floridan aquifer. The Floridan aquifer is overlain by the Pensacola clay confining bed, and the Bucatunna Clay subdivides it into two limestone units. Water in the upper limestone is generally of good quality. The lower limestone probably contains saline water. Average daily stream discharge is about 2,500 million gallons. Stream discharge does not diminish excessively during droughts, owing to high base runoff. Water levels in the Floridan aquifer will decline as long as pumping increases in the present areas of withdrawal. The decline could be alleviated by redistribution of pumping, artificial recharge, and the use of the sand-and-gravel aquifer or streams. (Woodard-USGS)

  6. Light emission in water-containing cocrystals: the influence of water molecules on the fluorescence properties of a Schiff-base molecule.

    PubMed

    Zhou, Feng; Tan, Pengli; Ma, Yong; Li, Youyong; Li, Najun; Li, Hua; Wang, Lihua; Gu, Hongwei; Xu, Qingfeng; Lu, Jianmei

    2014-01-01

    In the presence or absence of water, a Schiff-base compound, 4-amino-3-(2-(2-hydroxybenzylidene)hydrazinyl)-1H-1,2,4-triazole-5(4H)-thione (HATT), forms different crystalline states (HATT, HATT·2H2O, and a lamellar structure, m-HATT·nH2O), which show different luminescence emission properties. Herein, we investigate the emission of HATT and the role of water molecules. A water molecule, which acts as both a hydrogen-bond acceptor and -donor, enlarges the distance between adjacent HATT molecules and hinders non-radiative decay pathways.

  7. Classical interaction model for the water molecule.

    PubMed

    Baranyai, András; Bartók, Albert

    2007-05-14

    The authors propose a new classical model for the water molecule. The geometry of the molecule is built on the rigid TIP5P model and has the experimental gas phase dipole moment of water created by four equal point charges. The model preserves its rigidity but the size of the charges increases or decreases following the electric field created by the rest of the molecules. The polarization is expressed by an electric field dependent nonlinear polarization function. The increasing dipole of the molecule slightly increases the size of the water molecule expressed by the oxygen-centered sigma parameter of the Lennard-Jones interaction. After refining the adjustable parameters, the authors performed Monte Carlo simulations to check the ability of the new model in the ice, liquid, and gas phases. They determined the density and internal energy of several ice polymorphs, liquid water, and gaseous water and calculated the heat capacity, the isothermal compressibility, the isobar heat expansion coefficients, and the dielectric constant of ambient water. They also determined the pair-correlation functions of ambient water and calculated the energy of the water dimer. The accuracy of theirs results was satisfactory.

  8. Regional Jurassic geologic framework of Alabama coastal waters area and adjacent Federal waters area

    USGS Publications Warehouse

    Mink, R.M.; Bearden, B.L.; Mancini, E.A.

    1989-01-01

    To date, numerous Jurassic hydrocarbon fields and pools have been discovered in the Cotton Valley Group, Haynesville Formation, Smackover Formation and Norphlet Formation in the tri-state area of Mississippi, Alabama and Florida, and in Alabama State coastal waters and adjacent Federal waters area. Petroleum traps are basement highs, salt anticlines, faulted salt anticlines and extensional faults associated with salt movement. Reservoirs include continental and marine sandstones, limestones and dolostones. Hydrocarbon types are oil, condensate and natural gas. The onshore stratigraphic and structural information can be used to establish a regional geologic framework for the Jurassic for the State coastal waters and adjacent Federal waters areas. Evaluation of the geologic information along with the hydrocarbon data from the tri-state area indicates that at least three Jurassic hydrocarbon trends (oil, oil and gas condensate, and deep natural gas) can be identified onshore. These onshore hydrocarbon trends can be projected into the Mobile area in the Central Gulf of Mexico and into the Pensacola, Destin Dome and Apalachicola areas in the Eastern Gulf of Mexico. Substantial reserves of natural gas are expected to be present in Alabama State waters and the northern portion of the Mobile area. Significant accumulations of oil and gas condensate may be encountered in the Pensacola, Destin Dome, and Apalachicola areas. ?? 1989.

  9. Evidence of water molecules--a statistical evaluation of water molecules based on electron density.

    PubMed

    Nittinger, Eva; Schneider, Nadine; Lange, Gudrun; Rarey, Matthias

    2015-04-27

    Water molecules play important roles in many biological processes, especially when mediating protein-ligand interactions. Dehydration and the hydrophobic effect are of central importance for estimating binding affinities. Due to the specific geometric characteristics of hydrogen bond functions of water molecules, meaning two acceptor and two donor functions in a tetrahedral arrangement, they have to be modeled accurately. Despite many attempts in the past years, accurate prediction of water molecules-structurally as well as energetically-remains a grand challenge. One reason is certainly the lack of experimental data, since energetic contributions of water molecules can only be measured indirectly. However, on the structural side, the electron density clearly shows the positions of stable water molecules. This information has the potential to improve models on water structure and energy in proteins and protein interfaces. On the basis of a high-resolution subset of the Protein Data Bank, we have conducted an extensive statistical analysis of 2.3 million water molecules, discriminating those water molecules that are well resolved and those without much evidence of electron density. In order to perform this classification, we introduce a new measurement of electron density around an individual atom enabling the automatic quantification of experimental support. On the basis of this measurement, we present an analysis of water molecules with a detailed profile of geometric and structural features. This data, which is freely available, can be applied to not only modeling and validation of new water models in structural biology but also in molecular design.

  10. 33 CFR 110.140 - Buzzards Bay, Nantucket Sound, and adjacent waters, Mass.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Buzzards Bay, Nantucket Sound..., Nantucket Sound, and adjacent waters, Mass. (a) New Bedford Outer Harbor—(1) Anchorage A. West of Sconticut... Sounds—(1) Anchorage E. South of a line beginning at a point bearing 180° about 3.25 miles from...

  11. 33 CFR 110.140 - Buzzards Bay, Nantucket Sound, and adjacent waters, Mass.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Buzzards Bay, Nantucket Sound..., Nantucket Sound, and adjacent waters, Mass. (a) New Bedford Outer Harbor—(1) Anchorage A. West of Sconticut... Sounds—(1) Anchorage E. South of a line beginning at a point bearing 180° about 3.25 miles from...

  12. 33 CFR 110.140 - Buzzards Bay, Nantucket Sound, and adjacent waters, Mass.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Buzzards Bay, Nantucket Sound..., Nantucket Sound, and adjacent waters, Mass. (a) New Bedford Outer Harbor—(1) Anchorage A. West of Sconticut... Sounds—(1) Anchorage E. South of a line beginning at a point bearing 180° about 3.25 miles from...

  13. 33 CFR 110.140 - Buzzards Bay, Nantucket Sound, and adjacent waters, Mass.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Buzzards Bay, Nantucket Sound..., Nantucket Sound, and adjacent waters, Mass. (a) New Bedford Outer Harbor—(1) Anchorage A. West of Sconticut... Sounds—(1) Anchorage E. South of a line beginning at a point bearing 180° about 3.25 miles from...

  14. 33 CFR 110.140 - Buzzards Bay, Nantucket Sound, and adjacent waters, Mass.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Buzzards Bay, Nantucket Sound..., Nantucket Sound, and adjacent waters, Mass. Link to an amendment published at 76 FR 35744, June 20, 2011. (a... conduct lightering operations within these anchorages. (c) Vineyard and Nantucket Sounds—(1) Anchorage...

  15. 33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Puget Sound and Adjacent Waters... Areas Thirteenth Coast Guard District § 165.1301 Puget Sound and Adjacent Waters in Northwestern... northwestern Washington waters under the jurisdiction of the Captain of the Port, Puget Sound: Puget...

  16. 33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Puget Sound and Adjacent Waters... Areas Thirteenth Coast Guard District § 165.1301 Puget Sound and Adjacent Waters in Northwestern... northwestern Washington waters under the jurisdiction of the Captain of the Port, Puget Sound: Puget...

  17. 33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Puget Sound and Adjacent Waters... Areas Thirteenth Coast Guard District § 165.1301 Puget Sound and Adjacent Waters in Northwestern... northwestern Washington waters under the jurisdiction of the Captain of the Port, Puget Sound: Puget...

  18. 33 CFR 165.1301 - Puget Sound and Adjacent Waters in Northwestern Washington-Regulated Navigation Area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Puget Sound and Adjacent Waters... Areas Thirteenth Coast Guard District § 165.1301 Puget Sound and Adjacent Waters in Northwestern... northwestern Washington waters under the jurisdiction of the Captain of the Port, Puget Sound: Puget...

  19. 33 CFR 334.420 - Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Pamlico Sound and adjacent waters... REGULATIONS § 334.420 Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations. (a) Bombing and rocket firing area in Pamlico Sound in vicinity of Brant Island—(1) The area. The...

  20. 33 CFR 334.420 - Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Pamlico Sound and adjacent waters... REGULATIONS § 334.420 Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations. (a) Bombing and rocket firing area in Pamlico Sound in vicinity of Brant Island—(1) The area. The...

  1. Rotational motion of a single water molecule in a buckyball.

    PubMed

    Farimani, A Barati; Wu, Yanbin; Aluru, N R

    2013-11-07

    Encapsulation of a single water molecule in a buckyball (C60) can provide fundamental insights into the properties of water. Investigation of a single water molecule is feasible through its solitary confinement in C60. In this paper, we performed a detailed study of the properties and dynamics of a single water molecule in a buckyball using DFT and MD simulations. We report on the enhancement of rotational diffusion and entropy of a water molecule in C60, compared to a bulk water molecule. H2O@C60 has zero translational diffusion and terahertz revolution frequency. The harmonic, high amplitude rotation of a single water molecule in C60 is compared to stochastic behavior of bulk water molecules. The combination of large rotational and negligible translational motion of water in C60 creates new opportunities in nanotechnology applications.

  2. 33 CFR 165.1310 - Strait of Juan de Fuca and adjacent coastal waters of Northwest Washington; Makah Whale Hunting...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... adjacent coastal waters of Northwest Washington; Makah Whale Hunting-Regulated Navigation Area. 165.1310... and adjacent coastal waters of Northwest Washington; Makah Whale Hunting—Regulated Navigation Area. (a.... Datum: NAD 1983. (b) During a whale hunt, while the international numeral pennant five (5) is flown by...

  3. 33 CFR 165.1310 - Strait of Juan de Fuca and adjacent coastal waters of Northwest Washington; Makah Whale Hunting...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... adjacent coastal waters of Northwest Washington; Makah Whale Hunting-Regulated Navigation Area. 165.1310... and adjacent coastal waters of Northwest Washington; Makah Whale Hunting—Regulated Navigation Area. (a.... Datum: NAD 1983. (b) During a whale hunt, while the international numeral pennant five (5) is flown by...

  4. 33 CFR 165.1310 - Strait of Juan de Fuca and adjacent coastal waters of Northwest Washington; Makah Whale Hunting...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... adjacent coastal waters of Northwest Washington; Makah Whale Hunting-Regulated Navigation Area. 165.1310... and adjacent coastal waters of Northwest Washington; Makah Whale Hunting—Regulated Navigation Area. (a.... Datum: NAD 1983. (b) During a whale hunt, while the international numeral pennant five (5) is flown by...

  5. 33 CFR 165.1310 - Strait of Juan de Fuca and adjacent coastal waters of Northwest Washington; Makah Whale Hunting...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... adjacent coastal waters of Northwest Washington; Makah Whale Hunting-Regulated Navigation Area. 165.1310... and adjacent coastal waters of Northwest Washington; Makah Whale Hunting—Regulated Navigation Area. (a.... Datum: NAD 1983. (b) During a whale hunt, while the international numeral pennant five (5) is flown by...

  6. 33 CFR 165.1317 - Security and Safety Zone; Large Passenger Vessel Protection, Puget Sound and adjacent waters...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Passenger Vessel Protection, Puget Sound and adjacent waters, Washington. 165.1317 Section 165.1317... Vessel Protection, Puget Sound and adjacent waters, Washington. (a) Notice of enforcement or suspension... be enforced only upon notice by the Captain of the Port Puget Sound. Captain of the Port Puget...

  7. 33 CFR 165.1317 - Security and Safety Zone; Large Passenger Vessel Protection, Puget Sound and adjacent waters...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Passenger Vessel Protection, Puget Sound and adjacent waters, Washington. 165.1317 Section 165.1317... Vessel Protection, Puget Sound and adjacent waters, Washington. (a) Notice of enforcement or suspension... be enforced only upon notice by the Captain of the Port Puget Sound. Captain of the Port Puget...

  8. 33 CFR 165.1317 - Security and Safety Zone; Large Passenger Vessel Protection, Puget Sound and adjacent waters...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Passenger Vessel Protection, Puget Sound and adjacent waters, Washington. 165.1317 Section 165.1317... Vessel Protection, Puget Sound and adjacent waters, Washington. (a) Notice of enforcement or suspension... be enforced only upon notice by the Captain of the Port Puget Sound. Captain of the Port Puget...

  9. 33 CFR 165.1313 - Security zone regulations, tank ship protection, Puget Sound and adjacent waters, Washington

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ship protection, Puget Sound and adjacent waters, Washington 165.1313 Section 165.1313 Navigation and... Sound and adjacent waters, Washington (a) Notice of enforcement or suspension of enforcement. The tank... Port Puget Sound. Captain of the Port Puget Sound will cause notice of the enforcement of the tank...

  10. 33 CFR 165.1313 - Security zone regulations, tank ship protection, Puget Sound and adjacent waters, Washington

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... ship protection, Puget Sound and adjacent waters, Washington 165.1313 Section 165.1313 Navigation and... Sound and adjacent waters, Washington (a) Notice of enforcement or suspension of enforcement. The tank... Port Puget Sound. Captain of the Port Puget Sound will cause notice of the enforcement of the tank...

  11. 33 CFR 165.1313 - Security zone regulations, tank ship protection, Puget Sound and adjacent waters, Washington

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ship protection, Puget Sound and adjacent waters, Washington 165.1313 Section 165.1313 Navigation and... Sound and adjacent waters, Washington (a) Notice of enforcement or suspension of enforcement. The tank... Port Puget Sound. Captain of the Port Puget Sound will cause notice of the enforcement of the tank...

  12. 33 CFR 165.1317 - Security and Safety Zone; Large Passenger Vessel Protection, Puget Sound and adjacent waters...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Passenger Vessel Protection, Puget Sound and adjacent waters, Washington. 165.1317 Section 165.1317... Vessel Protection, Puget Sound and adjacent waters, Washington. (a) Notice of enforcement or suspension... be enforced only upon notice by the Captain of the Port Puget Sound. Captain of the Port Puget...

  13. 33 CFR 165.1313 - Security zone regulations, tank ship protection, Puget Sound and adjacent waters, Washington

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Port Puget Sound. Captain of the Port Puget Sound will cause notice of the enforcement of the tank ship... ship protection, Puget Sound and adjacent waters, Washington 165.1313 Section 165.1313 Navigation and... Sound and adjacent waters, Washington (a) Notice of enforcement or suspension of enforcement. The...

  14. 33 CFR 165.1310 - Strait of Juan de Fuca and adjacent coastal waters of Northwest Washington; Makah Whale Hunting...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... adjacent coastal waters of Northwest Washington; Makah Whale Hunting-Regulated Navigation Area. 165.1310... and adjacent coastal waters of Northwest Washington; Makah Whale Hunting—Regulated Navigation Area. (a.... Datum: NAD 1983. (b) During a whale hunt, while the international numeral pennant five (5) is flown by...

  15. Oyster Shell Dredging in Atchafalaya Bay and Adjacent Waters, Louisiana. Volume 2. Public Comments.

    DTIC Science & Technology

    1987-11-01

    Dredging in Atchafalaya Bay and Adjacent Waters, Louisiana. We appreciate the opportunity to review the DEIS. Sincerely yours, David Cottinginm Ecology ...subsequent effects on the aquatic ecosystem . General evaluation and testing procedures are outlined in the 404(b)(1) guidelines [Section 230.60 of Subpart G3...does not include zones 4-9 as integral parts of the regional ecosystem . The overall cummulative impact to the biology of the region can only be

  16. Temporal and spatial distribution of dissolved oxygen in the Pearl River Estuary and adjacent coastal waters

    NASA Astrophysics Data System (ADS)

    Yin, Kedong; Lin, Zhifeng; Ke, Zhiyuan

    2004-10-01

    The Pearl River is one of the large rivers in the world and it discharges to the northern part of the South China Sea. There has been a concern about the deterioration of dissolved oxygen conditions in the Pearl River estuary and adjacent coastal waters. In this study, historical data on dissolved oxygen (DO) from 1980s, recent data from a summer cruise in 1999, and a 10-year time series in DO for 1990-2000 were used to examine spatial and temporal distribution of DO in the Pearl River estuary and adjacent coastal waters near Hong Kong. In the adjacent coastal waters, low oxygen waters <4 mg l-1 occurred in large areas during the summer of 1981, but DO rarely dropped to <3 mg l-1. In the Pearl River estuary, DO was 3.5-4 mg l-1 in the eastern part, but was >4 mg l-1 in the western part in August 1984. In July 1999, DO was<4 mg l-1 in a near bottom 2 m layer in a large area of the estuary and was <2.5 mg l-1 in the eastern section, just inside the entrance of the estuary. In the coastal waters adjacent to Hong Kong, DO was>4 mg l-1. The 9-year time series showed that DO decreased periodically in summer, but rarely dropped to <3 mg l-1. There was no apparent trend of decreasing DO between 1990 and 2000. Compared to August 1984, DO decreased significantly during the summer of 1999 in the Pearl River estuary, but large scale hypoxia (<2 mg l-1) was not observed. The spatial distribution of low oxygen waters may be controlled by estuarine circulation because DO was significantly correlated with salinity in the summers of 1981 and 1984. Furthermore, the spatial distribution of DO in the bottom layer was parallel to the topography of the bottom, indicating the importance of benthic consumption of DO in the sediment and the subsequent flux of low DO waters from the sediment-water interface resuspended by physical mixing. Relative to the high loading of nitrogen from the Pearl River, the present PO4 concentration is still low. It is possible that the lack of large areas of

  17. Water resources of the Waccasassa River Basin and adjacent areas, Florida

    USGS Publications Warehouse

    Taylor, G.F.; Snell, L.J.

    1978-01-01

    This map report was prepared in cooperation with the Southwest Florida Water Management District which, with the Waccasassa River Basin Board, had jurisdiction over waters within the Waccasassa River basin, the coastal areas adjacent to the basin, and other adjacent areas outside the basin. New water management district boundaries, effective January 1977, place most of the Waccasassa River basin in the Suwannee River Water Management District. The purpose of the report is to provide water information for consideration in land-use and water development which is accelerating, especially in the northeastern part of the study area. It is based largely on existing data in the relatively undeveloped area. Of the total area included in the topographic drainage basin for the Waccasassa River about 72 percent is in Levy County, 18 percent in Alachua County, 9 percent in Gilchrist County, and 1 percent in Marion County. The elongated north-south drainage basin is approximately 50 mi in length, averages 13 mi in width, and lies between the Suwannee River, the St. Johns River, and the Withlacoochee River basins. (Woodard-USGS)

  18. Two new species in the family Axinellidae (Porifera, Demospongiae) from British Columbia and adjacent waters

    PubMed Central

    Austin, William C.; Ott, Bruce S.; Reiswig, Henry M.; Romagosa, Paula; McDaniel, Neil G.

    2013-01-01

    Abstract Two new species of Demospongiae are described for British Columbia and adjacent waters in the family Axinellidae, Auletta krautteri sp. n. and Dragmacidon kishinensis sp. n. They represent range extensions for both of these genera. Both are fairly commonly encountered, Auletta krautteri below diving depths (87 to at least 300 m) and Dragmacidon kishinensis in shallow water (intertidal to 30 m). We propose an amended genus diagnosis for Auletta to account for the variability among species in principal spicules that form the ascending tracts to be either oxeas, styles or strongyles rather than just oxeas. PMID:24146581

  19. Summary of ground-water data, Post Headquarters and adjacent areas, White Sands Missile Range

    USGS Publications Warehouse

    Kelly, T.E.

    1973-01-01

    Geohydrologic data have been obtained from more than 100 wells and test holes that have been drilled in the Post Headquarters and adjacent areas of White Sands Missile Range. Observation-well data show that, in general, a continuous decline of the water table has occurred in the vicinity of the well field since production began in 1949. Approximately 40,000 acre-feet of water has been produced from the aquifer to date (1972). A series of maps are presented which show the changes that have occurred in the well field as the result of development.

  20. Seasonal variability of nutrients in the Yangtze Estuary and adjacent waters: A model study

    NASA Astrophysics Data System (ADS)

    Zong, H.; Ding, P.

    2014-12-01

    Eutrophication has been one of the major threats to the coastal ecosystem. Several factors are believed to be associated with eutrophication, which including the high nutrient loads delivered into the estuary from river. Yangtze river is the longest river in China. It brings huge amount of nutrients into the Yangtze Estuary (YE) and adjacent East China Sea (ECS) and contributes significantly to the eutrophication in estuary and the adjacent waters. The eutrophication in this region exhibits strong seasonal variability, with the worst situation occurring in summer. This seasonal variability might be coupled with the timing of riverine nutrient inputs and physical processes (wind and along-shore current). To study seasonal variability of nutrients (N/P) in YE, a 3D physical-biological coupled model was applied to the YE and its adjacent waters. The physical model was the Regional Ocean Model System (ROMS) and the biological model was a nitrogen, phytoplankton, zooplankton, and detritus (NPZD) model. The simulated nutrients distribution pattern was consistent with observation. With the numerical experiments, we examined nutrients transport under different river loads and different physical processes. Seasonal variability of nutrients budget in YE and alone-shelf transport flux were also studied.

  1. Dissociative Electron Attachment of Water Molecules

    NASA Astrophysics Data System (ADS)

    Belkacem, Ali; Adaniya, Hidehito; Osipov, Timur; Weber, Thorsten; Lee, Sun Y.; Hertlein, Marcus; Rudek, Benedikt

    2008-05-01

    A Coltrims method is developed to measure the kinetic energy and angular distribution of fragment negative ions arising from dissociative electron attachment of molecules. A low energy pulsed electron gun is used in combination with pulsing the extraction plates of the Coltrims spectrometer. This technique is applied to study the negative oxygen anion channel for the three resonances, ^2B1, ^2A1, and ^2B2 resonances of water. The measured kinetic energy of the O- fragment gives a good measure of the two-body channel versus three-body channel for each resonance. The angular distribution of the O- fragments with respect tom the electron beam direction is found reflect well the symmetry of the resonance state. The experimental results are compared to the theoretical predictions.

  2. Water: one molecule, two surfaces, one mistake

    NASA Astrophysics Data System (ADS)

    Vega, Carlos

    2015-05-01

    In order to rigorously evaluate the energy and dipole moment of a certain configuration of molecules, one needs to solve the Schrödinger equation. Repeating this for many different configurations allows one to determine the potential energy surface (PES) and the dipole moment surface (DMS). Since the early days of computer simulation, it has been implicitly accepted that for empirical potentials the charges used to fit the PES should also be used to describe the DMS. This is a mistake. Partial charges are not observable magnitudes. They should be regarded as adjustable fitting parameters. Optimal values used to describe the PES are not necessarily the best to describe the DMS. One could use two fits: one for the PES and the other for the DMS. This is a common practice in the quantum chemistry community, but not used so often by the community performing computer simulations. This idea affects all types of modelling of water (with the exception of ab initio calculations) from coarse-grained to non-polarisable and polarisable models. We anticipate that an area that will benefit dramatically from having both, a good PES and a good DMS, is the modelling of water in the presence of electric fields.

  3. Ground-water hydrology of Pahvant Valley and adjacent areas, Utah

    USGS Publications Warehouse

    1990-01-01

    The primary ground-water reservoir in Pahvant Valley and adjacent areas is in the unconsolidated basin fill and interbedded basalt. Recharge in 1959 was estimated to be about 70,000 acre-feet per year and was mostly by seepage from streams, canals, and unconsumed irrigation water and by infiltration of precipitation. Discharge in 1959 was estimated to be about 109,000 acre-feet and was mostly from springs, evapotranspiration, and wells.Water-level declines of more than 50 feet occurred in some areas between 1953 and 1980 because of less-than-normal precipitation and extensive pumping for irrigation. Water levels recovered most of these declines between 1983 and 1986 because of reduced withdrawals and record quantities of precipitation.The quality of ground water in the area west of Kanosh has deteriorated since large ground-water withdrawals began in about 1953. The cause of the deterioration probably is movement of poor quality water into the area from the southwest and possibly the west during periods of large ground-water withdrawals and recycling of irrigation water. The quality of water from some wells has improved since 1983, due to increased recharge and decreased withdrawals for irrigation.Water-level declines of m:>re than 80 feet in some parts of Pahvant Valley are projected if ground-water withdrawals continue for 20 years at the 1977 rate of about 96,000 acre-feet. Rises of as much as 58 feet and declines of as much as 47 feet are projected with withdrawals of 48,000 acre-feet per year for 20 years. The elimination of recharge from the Central Utah Canal is projected to cause water-level declines of up to 8 feet near the canal.

  4. Measures of Water Quality in Merrit Island National Wildlife Refuge Impoundments and Adjacent Indian River Lagoon

    NASA Technical Reports Server (NTRS)

    Blum, Linda K.

    2000-01-01

    The goal of this project was to conduct preliminary investigations to determine appropriate sampling strategies to measure the flux of dissolved nutrients (specifically, NH4+, NO3-, NO2-, and PO4(3-)) and suspended particulate matter (TSS) between impoundments and the IRL in preparation for an intensive three-year monitoring program. In addition to nutrients and TSS, a variety of common water quality indicators were also measured during these preliminary studies. Six impoundments and a single restored marsh were selected for study. Over a month long period, water samples were collected weekly at selected impoundment culverts. Water was collected in duplicate as independent grab samples from both the lagoon side and within the perimeter ditch directly adjacent to the culverts. Water quality indicators inside and outside the marsh impoundments were different. Ammonium, salinity, bacteria, and chlorophyll-a were higher inside the impoundments as expected possibly as a result of the great affect of evaporation on impoundment water. Water quality indicators responded rapidly both inside and outside the impoundments as exemplified by the increase in NH4(+)-N concentrations during a horseshoe crab die-off. Water quality indicators were high variable during the month in which water samples were collected. Because the impoundments are widely spaced it is logistically unrealistic to sample each of the impoundments and associated seagrass beds on a single day, sampling must be stratified to allow patterns of material movement and the annual flux of materials to and from the impoundments to be determined.

  5. Contrasting microbial assemblages in adjacent water masses associated with the East Australian Current.

    PubMed

    Seymour, Justin R; Doblin, Martina A; Jeffries, Thomas C; Brown, Mark V; Newton, Kelly; Ralph, Peter J; Baird, Mark; Mitchell, James G

    2012-10-01

    Different oceanographic provinces host discrete microbial assemblages that are adapted to local physicochemical conditions. We sequenced and compared the metagenomes of two microbial communities inhabiting adjacent water masses in the Tasman Sea, where the recent strengthening of the East Australian Current (EAC) has altered the ecology of coastal environments. Despite the comparable latitude of the samples, significant phylogenetic differences were apparent, including shifts in the relative frequency of matches to Cyanobacteria, Crenarchaeota and Euryarchaeota. Fine-scale variability in the structure of SAR11, Prochlorococcus and Synechococcus populations, with more matches to 'warm-water' ecotypes observed in the EAC, indicates the EAC may drive an intrusion of tropical microbes into temperate regions of the Tasman Sea. Furthermore, significant shifts in the relative importance of 17 metabolic categories indicate that the EAC prokaryotic community has different physiological properties than surrounding waters.

  6. Literature and data review for the surface-water pathway: Columbia River and adjacent coastal areas

    SciTech Connect

    Walters, W.H.; Dirkes, R.L.; Napier, B.A.

    1992-11-01

    As part of the Hanford Environmental Dose Reconstruction (HEDR) Project, Battelle, Pacific Northwest Laboratories reviewed literature and data on radionuclide concentrations and distribution in the water, sediment, and biota of the Columbia River and adjacent coastal areas. Over 600 documents were reviewed including Hanford reports, reports by offsite agencies, journal articles, and graduate theses. Radionuclide concentration data were used in preliminary estimates of individual dose for the period 1964 through 1966. This report summarizes the literature and database reviews and the results of the preliminary dose estimates.

  7. Literature and data review for the surface-water pathway: Columbia River and adjacent coastal areas

    SciTech Connect

    Walters, W.H.; Dirkes, R.L.; Napier, B.A.

    1992-04-01

    As part of the Hanford Environmental Dose Reconstruction Project, Pacific Northwest Laboratory reviewed literature and data on radionuclide concentrations and distribution in the water, sediment, and biota of the Columbia River and adjacent coastal areas. Over 600 documents were reviewed including Hanford reports, reports by offsite agencies, journal articles, and graduate theses. Certain radionuclide concentration data were used in preliminary estimates of individual dose for the 1964--1966 time period. This report summarizes the literature and database review and the results of the preliminary dose estimates.

  8. The Large Quadrupole of Water Molecules

    SciTech Connect

    Niu, Shuqiang; Tan, Ming-Liang; Ichiye, Toshhiko

    2011-04-07

    Many quantum mechanical calculations indicate water molecules in the gas and liquid phase have much larger quadrupole moments than any of the common site models of water for computer simulations. Here, comparisons of multipoles from quantum mechanical/molecular mechanical (QM/MM) calculations at the MP2/aug-cc-pVQZ level on a B3LYP/aug-cc-pVQZ level geometry of a waterlike cluster and from various site models show that the increased square planar quadrupole can be attributed to the p-orbital character perpendicular to the molecular plane of the highest occupied molecular orbital as well as a slight shift of negative charge toward the hydrogens. The common site models do not account for the p-orbital type electron density and fitting partial charges of TIP4P- or TIP5P-type models to the QM/MM dipole and quadrupole give unreasonable higher moments. Furthermore, six partial charge sites are necessary to account reasonably for the large quadrupole, and polarizable site models will not remedy the problem unless they account for the p-orbital in the gas phase since the QM calculations show it is present there too. On the other hand, multipole models by definition can use the correct multipoles and the electrostatic potential from the QM/MM multipoles is much closer than that from the site models to the potential from the QM/MM electron density. Finally, Monte Carlo simulations show that increasing the quadrupole in the soft-sticky dipole-quadrupole-octupole multipole model gives radial distribution functions that are in good agreement with experiment

  9. Origin of subdiffusion of water molecules on cell membrane surfaces

    PubMed Central

    Yamamoto, Eiji; Akimoto, Takuma; Yasui, Masato; Yasuoka, Kenji

    2014-01-01

    Water molecules play an important role in providing unique environments for biological reactions on cell membranes. It is widely believed that water molecules form bridges that connect lipid molecules and stabilize cell membranes. Using all-atom molecular dynamics simulations, we show that translational and rotational diffusion of water molecules on lipid membrane surfaces exhibit subdiffusion and aging. Moreover, we provide evidence that both divergent mean trapping time (continuous-time random walk) and long-correlated noise (fractional Brownian motion) contribute to this subdiffusion. These results suggest that subdiffusion on cell membranes causes the water retardation, an enhancement of cell membrane stability, and a higher reaction efficiency. PMID:24739933

  10. Estimated water use in the Southwest Florida Water Management District and adjacent areas, 1980

    USGS Publications Warehouse

    Duerr, A.D.; Trommer, J.T.

    1981-01-01

    Water-use data for 1980 are summarized in this report for 16 counties in the Southwest Florida Water Management District. Data include total use of ground water and surface water for each of five water-use categories. The 1980 withdrawals for each category were as follows: 290 million gallons per day for public supply, 63 million gallons per day for rural, 325 million gallons per day for industry, 416 million gallons per day for irrigation, and 6,605 million gallons per day for thermoelectric power generation. Withdrawals totaled 7,699 million gallons per day and included 983 million gallons per day of ground water and 6,716 million gallons per day of surface water. Excluding thermoelectric power generation, all water withdrawn was freshwater except 38 million gallons per day of saline ground water withdrawn for industrial use in Hillsborough County. (USGS)

  11. [Fish resources and their conservation strategies in Hepu Dugong State Nature Reserve and its adjacent waters].

    PubMed

    Wang, Qian; Yang, Guang; Wu, Xiaobing; Xu, Xinrong; Lai, Chunmiao; Ning, Yun; Luo, Jinfu

    2006-09-01

    An investigation was made on the fish resources and fish habitats of Hepu Dugong State Nature Reserve and its adjacent waters from June 2003 to May 2004. The local fish markets were surveyed, and fishermen and fishmongers were interviewed to get fishery information. A total of 57 fish species belonging to 41 families and 14 orders were recorded, among which, 55 were bony fish, and 2 were elasmobranch. There were 41 fish species belonging to warm-water fish, and 37 fish species belonging to benthonic fish. The faunal characteristic was mainly of Northern Pacific and Indo-Pacific fauna. Devastating fishing and environmental pollution were the most serious threats to the local fishery resources, and some countermeasures were proposed for conservation and management of the resources.

  12. Water quality in the lower Puyallup River valley and adjacent uplands, Pierce County, Washington

    USGS Publications Warehouse

    Ebbert, J.C.; Bortleson, Gilbert C.; Fuste, L.A.; Prych, E.A.

    1987-01-01

    The quality of most ground and surface water within and adjacent to the lower Puyallup River valley is suitable for most typical uses; however, some degradation of shallow groundwater quality has occurred. High concentrations of iron and manganese were found in groundwater, sampled at depths of < 40 ft, from wells tapping alluvial aquifers and in a few wells tapping deeper aquifers. Volatile and acid- and base/neutral-extractable organic compounds were not detected in either shallow or deep groundwater samples. The quality of shallow groundwater was generally poorer than that of deep water. Deep ground water (wells set below 100 ft) appears suitable as a supplementary water supply for fish-hatchery needs. Some degradation of water quality, was observed downstream from river mile 1.7 where a municipal wastewater-treatment plant discharges into the river. In the Puyallup River, the highest concentrations of most trace elements were found in bed sediments collected downstream from river mile 1.7. Median concentrations of arsenic, lead, and zinc were higher in bed sediments from small streams compared with those from the Puyallup River, possibly because the small stream drainages, which are almost entirely within developed areas, receive more urban runoff as a percentage of total flow. Total-recoverable trace-element concentrations exceeded water-quality criteria for acute toxicity in the Puyallup River and in some of the small streams. In most cases, high concentrations of total-recoverable trace elements occurred when suspended-sediment concentrations were high. Temperatures in all streams except Wapato Creek and Fife Dutch were within limits (18 C) for Washington State class A water. Minimum dissolved oxygen concentrations were relatively low at 5.6 and 2.0 mg/L, respectively, for Wapato Creek and Fife Dutch. The poorest surface-water quality, which can be characterized as generally unsuitable for fish, was in Fife Dutch, a manmade channel and therefore

  13. Concentration of hydrocarbons associated with particles in the shelf waters adjacent to the entrance of Chesapeake Bay

    NASA Technical Reports Server (NTRS)

    Wade, T. L.; Oertel, G. F.

    1981-01-01

    Particulate hydrocarbon concentrations were measured in 94 water samples. The concentrations ranged from below the detection limit ( 0.7 micro-G/L) to 32 micro-g/l. The mean for all samples was 5.6 micro-g/l. Particulate hydrocarbon concentrations are higher in the Bay mouth and lower in the shelf waters adjacent to the entrance of Chesapeake Bay. No coherent particulate hydrocarbon distribution is seen with depth in the water column. The Bay is postulated as one of the possible chronic sources of particulate hydrocarbons for the adjacent shelf waters.

  14. [Phytoplankton Light Absorption Properties During the Blooms in Adjacent Waters of the Changjiang Estuary].

    PubMed

    Liu, Yang-yang; Shen, Fang; Li, Xiu-zhen

    2015-06-01

    Phytoplankton dominant species and their light absorption properties during the blooms occurred in August 2013 in adjacent waters of the Changjiang Estuary were analyzed. The results showed that phytoplankton blooms broke out in 10 out of 34 investigation stations, among which diatom blooms occurred in 6 stations while 3 stations were predominated by dinoflagellate. Phytoplankton absorption coefficients of both bloom and non-bloom waters exhibited large variations, with respective ranges of 0.199-0.832 m(-1) and 0.012-0.109 m(-1), while phytoplankton specific absorption coefficients spanned much narrower range, with the average values of bloom and non-bloom waters being 0.023 and 0.035 m2 x mg(-1), respectively. When transitioned from bloom to non-bloom waters, the proportion of phytoplankton with larger cell size lowered while that of smaller phytoplankton elevated, causing a less extent of package effect and thus higher specific absorption coefficients. Distinctive absorption spectra were observed between different types of bloom (such as diatom and dinoflagellate blooms) with similar phytoplankton cell size, mostly attributed to distinctive accessory pigment composition. The ratios of diadinoxanthin and chlorophyll-c2 concentrations to chlorophyll-a concentration in dinoflagellate blooms were higher than those in diatom blooms, which largely contributed to the shoulder peaks at 465 nm in dinoflagellate blooms.

  15. Declining extent of open-water refugia for top predators in Baffin Bay and adjacent waters.

    PubMed

    Heide-Jørgensen, Mads Peter; Laidre, Kristin L

    2004-12-01

    Global climate change is expected to severely impact Arctic ecosystems, yet predictions of impacts are complicated by region-specific patterns and nonuniform trends. Twentyfour open-water overwintering areas (or "microhabitats") were identified to be of particular importance for eight seabird and marine mammal species in the eastern Canadian High Arctic and Baffin Bay. Localized trends in the available fraction of open-water were examined in March during 1979--2001, derived from approximate sea ice concentrations from satellite-based microwave telemetry. Declines in the fraction of open-water were identified at microhabitats in Baffin Bay, Davis Strait, coastal West Greenland, and Lancaster Sound. Increases in open-water were observed in Hudson Bay, Hudson Strait, and Foxe Basin. The biological importance of each microhabitat was examined based on species distribution and abundance. Potential consequences of reduced open-water for top marine predators include impacts on foraging efficiency and oxygen and prey availability.

  16. Hydrology, geochemistry and geothermal aspects of the thermal waters from Switzerland and adjacent alpine regions

    NASA Astrophysics Data System (ADS)

    Vuataz, François-David

    1983-11-01

    Waters of 19 thermal areas in Switzerland and adjacent alpine regions were studied to acquire a better knowledge of their deep thermal circulation, geochemistry and low-temperature geothermal potential. A systematic multisampling and multitracing program was executed over a complete hydrologic cycle for each of the 19 thermal areas. Pertinent physical, chemical and isotopic parameters were measured and analyzed on thermal and nonthermal waters during nine sampling periods. Thermal water occurrences are generally related either to Triassic evaporites or to the weathered and fractured zone between crystalline basements (or ranges) and their sedimentary cover. Emergence areas are located in faulted or overthrust zones. Sulfate and calcium are the two principal ions responsible for the mineralization of most thermal waters. Actually, gypsum and anhydrite are more often encountered in Triassic evaporites than halite. Many variations of the water geochemistry, caused by seasonal changes, have been recorded during the hydrologic cycle. From mineralization, temperature and discharge variations, it has been possible to distinguish fast or delayed responses to rain or snow-melt events and mixing between deep-thermal and shallow-cold waters. Chemical geothermometers were tested on these warm waters. The chalcedony and Na-K-Ca geothermometers seem to be the only ones which display calculated temperatures in reasonable agreement with known local geothermal gradients or bottom-hole temperatures. The majority of inferred reservoir temperatures ranges from 40° to 60°C. Oxygen-18 and deuterium results show that most thermal waters fit along the meteoric water line, with some exceptions due to Mediterranean precipitation, possible water-rock isotopic exchange or mixing with connate waters. A regional oxygen-18 gradient has been established with altitude in order to locate and determine the elevation of intake areas. Tritium is very useful in the detection of mixing between deep

  17. Selected ground-water information for the Pasco basin and adjacent areas, Washington, 1986-1989

    USGS Publications Warehouse

    Drost, B.W.; Schurr, K.M.; Lum, W. E.

    1989-01-01

    The U.S. Geological Survey, in cooperation with the United States Department of Energy, conducted a study of the Pasco basin and adjacent areas, Washington, in support of the Basalt Waste Isolation Project at the Hanford site, Washington. The purpose of the study was to develop a data set that would help define the groundwater-flow system of the Pasco Basin. This report contains the basic data, without interpretation, that were collected from the start of the project in February 1986 through January 1989. Information presented is from the U.S. Bureau of Reclamation, State of Washington Department of Ecology , US Army Corps of Engineers, Kennewick Irrigation District, and the Survey, and consists of well location and construction data, records of water levels in the wells, and aquifer designations for each well. The aquifer designation represents the geohydrologic unit to which the well is reported to be open. (USGS)

  18. [Temporal and spatial distribution of red tide in Yangtze River Estuary and adjacent waters].

    PubMed

    Liu, Lu-San; Li, Zi-Cheng; Zhou, Juan; Zheng, Bing-Hui; Tang, Jing-Liang

    2011-09-01

    The events of red tide were collected in Yangtze River Estuary and adjacent waters from 1972 to 2009. Based on geographic information system (GIS) analysis on the temporal and spatial distribution of red tide, the distribution map was generated accordingly. The results show: (1) There are three red tide-prone areas, which are outside the Yangtze River estuary and the eastern of Sheshan, Huaniaoshan-Shengshan-Gouqi, Zhoushan and the eastern of Zhujiajian. The red tide occurred 174 times in total, in which there were 25 times covered the area was larger than 1 000 km2. After 2000, the frequency of red tide were significantly increasing; (2) The frequent occurrence of red tide was in May (51% of total occurrence) and June (20% of total occurrence); (3) In all of the red tide plankton, the dominant species were Prorocentrum danghaiense, Skeletonema costatum, Prorocentrum dantatum, Nactiluca scientillans. The red tides caused by these species were 38, 35, 15, 10 times separately.

  19. Giant pumping of single-file water molecules in a carbon nanotube.

    PubMed

    Wang, Y; Zhao, Y J; Huang, J P

    2011-11-17

    Achieving a fast, unidirectional flow of single-file water molecules (UFSWM) across nanochannels is important for membrane-based water purification or seawater desalination. For this purpose, electro-osmosis methods are recognized as a very promising approach and have been extensively discussed in the literature. Utilizing molecular dynamics simulations, here we propose a design for pumping water molecules in a single-walled carbon nanotube in the presence of a linearly gradient electric (GE) field. Such a GE field is inspired by GE fields generated from charged ions located adjacent to biological membrane water nanochannels that can conduct water in and out of cells and can be experimentally achieved by using the charged tip of an atomic force microscope. As a result, the maximum speed of the UFSWM can be 1 or 2 orders of magnitude larger than that in a uniform electric (UE) field. Also, inverse transportation of water molecules does not exist in case of the GE field but can appear for the UE field. Thus, the GE field yields a much more efficient UFSWM than the UE field. The giant pumping ability as revealed is attributed to the nonzero net electrostatic force acting on each water molecule confined in the nanotube. These observations have significance for the design of nanoscale devices for readily achieving controllable UFSWM at high speed.

  20. Ground-water resources of southern Tangipahoa Parish and adjacent areas, Louisiana

    USGS Publications Warehouse

    Rapp, T.R.

    1994-01-01

    Groundwater resources in southern Tangipahoa Parish and adjacent areas were studied to determine their potential for development as an alternative to the Mississippi River as a water-supply source for Jefferson Parish. Eight major aquifers consisting of thick sand units that underlie the study area are, in descending order: (1) shallow, (2) upper Ponchatoula, (3) lower Ponchatoula, (4) Abita, (5) Covington, (6) Tchefuncta, (7) Hammond, and (8) Amite. A fault zone, referred to as the Baton Rouge fault, crosses southern Tangipahoa Parish. Analyses of geophysical logs indicated that the deep aquifers south of the fault zone had been displaced from 350 to 400 feet, and that the deeper aquifers were not in hydraulic connection with the flow system north of the fault. The groundwater resources of southeastern Louisiana are immense and the quality of groundwater in Tangipahoa Parish is suitable for most uses. The quality of water in these aquifers generally meets the U.S. Environmental Protection Agency's standards for public supply. The hydrologic system underlying Tangipahoa Parish and adjacent areas in 1990 supplied about 19 Mgal/d of water that was suitable for public supply. However, substantial increases in pumping from the aquifer system would result in renewed water-level declines throughout the hydrologic system until a new equilibrium is established. A test we11 in southern Tangipahoa Parish, penetrated all eight aquifers. Total thickness of freshwater sand beds penetrated by the 3003-ft test hole was more than 1900 ft. Resistivity values from an electric log of the test typically averaged 200 ohm-meters, which indicates that the water has low dissolved-solids and chloride concentrations. An analysis of the Abita aquifer at Ruddock in St. John the Baptist Parish, for two of three hypothetical well fields, indicated that for a hypothetical we11 field with a pumping rate of 112 Mgal/d, the freshwater/saltwater interface could arrive at the outer perimeter we11 in

  1. 33 CFR 334.410 - Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Albemarle Sound, Pamlico Sound... AND RESTRICTED AREA REGULATIONS § 334.410 Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations. (a) Target areas—(1) North Landing River (Currituck...

  2. 33 CFR 334.412 - Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Albemarle Sound, Pamlico Sound... REGULATIONS § 334.412 Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area. (a) The area. Beginning on the north shore of Albemarle Sound and the easternmost tip of Harvey...

  3. 33 CFR 334.410 - Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Albemarle Sound, Pamlico Sound... AND RESTRICTED AREA REGULATIONS § 334.410 Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations. (a) Target areas—(1) North Landing River (Currituck...

  4. 33 CFR 334.412 - Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Albemarle Sound, Pamlico Sound... REGULATIONS § 334.412 Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area. (a) The area. Beginning on the north shore of Albemarle Sound and the easternmost tip of Harvey...

  5. 33 CFR 334.412 - Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Albemarle Sound, Pamlico Sound... REGULATIONS § 334.412 Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area. (a) The area. Beginning on the north shore of Albemarle Sound and the easternmost tip of Harvey...

  6. 33 CFR 334.412 - Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Albemarle Sound, Pamlico Sound... REGULATIONS § 334.412 Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area. (a) The area. Beginning on the north shore of Albemarle Sound and the easternmost tip of Harvey...

  7. 33 CFR 334.412 - Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Albemarle Sound, Pamlico Sound... REGULATIONS § 334.412 Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area. (a) The area. Beginning on the north shore of Albemarle Sound and the easternmost tip of Harvey...

  8. 33 CFR 334.410 - Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Albemarle Sound, Pamlico Sound... AND RESTRICTED AREA REGULATIONS § 334.410 Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations. (a) Target areas—(1) North Landing River (Currituck...

  9. 33 CFR 334.410 - Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Albemarle Sound, Pamlico Sound... AND RESTRICTED AREA REGULATIONS § 334.410 Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations. (a) Target areas—(1) North Landing River (Currituck...

  10. 33 CFR 334.410 - Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Albemarle Sound, Pamlico Sound... AND RESTRICTED AREA REGULATIONS § 334.410 Albemarle Sound, Pamlico Sound, and adjacent waters, NC; danger zones for naval aircraft operations. (a) Target areas—(1) North Landing River (Currituck...

  11. Microbial water quality before and after the repair of a failing onsite wastewater treatment system adjacent to coastal waters

    USGS Publications Warehouse

    Conn, K.E.; Habteselassie, M.Y.; Denene, Blackwood A.; Noble, R.T.

    2012-01-01

    Aims: The objective was to assess the impacts of repairing a failing onsite wastewater treatment system (OWTS, i.e., septic system) as related to coastal microbial water quality. Methods and Results: Wastewater, groundwater and surface water were monitored for environmental parameters, faecal indicator bacteria (total coliforms, Escherichia coli, enterococci) and the viral tracer MS2 before and after repairing a failing OWTS. MS2 results using plaque enumeration and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) often agreed, but inhibition limited the qRT-PCR assay sensitivity. Prerepair, MS2 persisted in groundwater and was detected in the nearby creek; postrepair, it was not detected. In groundwater, total coliform concentrations were lower and E.??coli was not detected, while enterococci concentrations were similar to prerepair levels. E.??coli and enterococci surface water concentrations were elevated both before and after the repair. Conclusions: Repairing the failing OWTS improved groundwater microbial water quality, although persistence of bacteria in surface water suggests that the OWTS was not the singular faecal contributor to adjacent coastal waters. A suite of tracers is needed to fully assess OWTS performance in treating microbial contaminants and related impacts on receiving waters. Molecular methods like qRT-PCR have potential but require optimization. Significance and Impact of Study: This is the first before and after study of a failing OWTS and provides guidance on selection of microbial tracers and methods. ?? 2011 The Authors. Journal of Applied Microbiology ?? 2011 The Society for Applied Microbiology.

  12. (π*,σ*), (σ*,π*) and Rydberg triplet excited states of hydrogen peroxide and other molecules bearing two adjacent heteroatoms.

    PubMed

    Hill, J Grant; Bucher, Götz

    2014-03-27

    The properties of the lowest triplet excited states of a series of small molecules containing two or more adjacent heteroatoms have been investigated. High-level coupled cluster and MRCI+Q calculations were employed to probe the properties of the triplet excited states of hydrogen peroxide, hydrazine, hydroxylamine, fluoroamines, oxygen difluoride, hypofluorous acid, chlorine, fluorine, and disulfane. All of the molecules investigated except hydroxylamine are predicted to have bound lowest triplet excited states that are either (π*,σ*) or (σ*,π*) as in H2O2, HOF, OF2, H2S2, Cl2, NH2F, NHF2, or NF3, or are Rydberg states (hydrazine, also H2O2 and H2S2). The heteroatom-heteroatom bond dissociation enthalpies of the triplet states range from very small values as predicted for hydrogen peroxide or fluorine, to BDEs around 8-9 kcal mol(-1) that should allow for an experimental observation of the triplet state, such as in disulfane or monofluoroamine. For all triplet minima investigated except NF3 and F2, CCSD(T) gave results in agreement with the multireference method MRCI+Q, and in excellent agreement with available experimental data (BDEs, ground-state geometries). Due to multireference problems, CCSD(T) does not provide a good description for longer heteroatom-heteroatom distances, and in some cases (e.g., Cl2) it wrongly predicts the presence of a transition state for bond formation on the triplet spin manifold, where the reaction is known experimentally and, as predicted by MRCI+Q, is known to be barrierless. Finally, the (3)Π(u) state of F2 is poorly described by CCSD(T) theory, the equilibrium bond distance is significantly underestimated relative to MRCI+Q, and CCSD(T) places the triplet state above the energy of two fluorine atoms. The T1 diagnostic, frequently used to assess the quality of CCSD(T) calculations, does not appear to provide a valid criterion for the systems studied. The formation of H2O2 on the triplet potential energy hypersurface might

  13. Free enthalpies of replacing water molecules in protein binding pockets

    NASA Astrophysics Data System (ADS)

    Riniker, Sereina; Barandun, Luzi J.; Diederich, François; Krämer, Oliver; Steffen, Andreas; van Gunsteren, Wilfred F.

    2012-12-01

    Water molecules in the binding pocket of a protein and their role in ligand binding have increasingly raised interest in recent years. Displacement of such water molecules by ligand atoms can be either favourable or unfavourable for ligand binding depending on the change in free enthalpy. In this study, we investigate the displacement of water molecules by an apolar probe in the binding pocket of two proteins, cyclin-dependent kinase 2 and tRNA-guanine transglycosylase, using the method of enveloping distribution sampling (EDS) to obtain free enthalpy differences. In both cases, a ligand core is placed inside the respective pocket and the remaining water molecules are converted to apolar probes, both individually and in pairs. The free enthalpy difference between a water molecule and a CH3 group at the same location in the pocket in comparison to their presence in bulk solution calculated from EDS molecular dynamics simulations corresponds to the binding free enthalpy of CH3 at this location. From the free enthalpy difference and the enthalpy difference, the entropic contribution of the displacement can be obtained too. The overlay of the resulting occupancy volumes of the water molecules with crystal structures of analogous ligands shows qualitative correlation between experimentally measured inhibition constants and the calculated free enthalpy differences. Thus, such an EDS analysis of the water molecules in the binding pocket may give valuable insight for potency optimization in drug design.

  14. Free enthalpies of replacing water molecules in protein binding pockets.

    PubMed

    Riniker, Sereina; Barandun, Luzi J; Diederich, François; Krämer, Oliver; Steffen, Andreas; van Gunsteren, Wilfred F

    2012-12-01

    Water molecules in the binding pocket of a protein and their role in ligand binding have increasingly raised interest in recent years. Displacement of such water molecules by ligand atoms can be either favourable or unfavourable for ligand binding depending on the change in free enthalpy. In this study, we investigate the displacement of water molecules by an apolar probe in the binding pocket of two proteins, cyclin-dependent kinase 2 and tRNA-guanine transglycosylase, using the method of enveloping distribution sampling (EDS) to obtain free enthalpy differences. In both cases, a ligand core is placed inside the respective pocket and the remaining water molecules are converted to apolar probes, both individually and in pairs. The free enthalpy difference between a water molecule and a CH(3) group at the same location in the pocket in comparison to their presence in bulk solution calculated from EDS molecular dynamics simulations corresponds to the binding free enthalpy of CH(3) at this location. From the free enthalpy difference and the enthalpy difference, the entropic contribution of the displacement can be obtained too. The overlay of the resulting occupancy volumes of the water molecules with crystal structures of analogous ligands shows qualitative correlation between experimentally measured inhibition constants and the calculated free enthalpy differences. Thus, such an EDS analysis of the water molecules in the binding pocket may give valuable insight for potency optimization in drug design.

  15. Water resources of the Rincon and Mesilla Valleys and adjacent areas, New Mexico

    USGS Publications Warehouse

    Wilson, Clyde A.; White, Robert R.; Orr, Brennon R.; Roybal, R. Gary

    1981-01-01

    valleys in the adjacent upland areas. Ground water moves southeastward beneath the West Mesa area, converging with ground-water flow in the southern end of the Mesilla Valley. Good hydraulic connection exists between sediments of the West Mesa and Mesilla Valley areas. Ground water in the southern end of the Jornada del Muerto moves generally to the northwest, converges with south-flowing ground water near Point of Rocks, and moves westward into Rincon Valley sediments near Rincon. A small amount of ground water flows westward from the southern end of the Jornada del Muerto across a subsurface igneous body into the Mesilla Valley. Ground-water discharge occurs throughout the Rincon and Mesilla Valleys as drain flow to the river and evapotranspiration. Dissolved-solids concentrations in the water in the flood-plain alluvium of the Rincon and Mesilla Valleys are generally greater than 1,000 milligrams per liter. A freshwater zone, with dissolved-solids concentrations less than 1,000 milligrams per liter, underlies this thin, slightly saline zone beneath much of the Mesilla Valley. This freshwater zone, occurring in the Santa Fe Group, is surrounded by saline water. Within the study area, major dissolved ions in ground water include sodium, calcium, bicarbonate, and sulfate. The Rio Grande is a gainlng stream in the northern parts of the Rincon and Mesilla Valleys and a losing stream in the southern part of the Mesilla Valley. Gains and losses result from a close interconnection with ground-water flow systems. Large surface-water irrigation allotments increase ground-water recharge. Increased recharge raises ground-water levels and improves shallow ground-water quality adjacent to these recharge areas. Shallow ground-water discharges to drains, which flow into the Rio Grande. Dissolved-solids concentrations in the Rio Grande increase by as much as 60 percent between Caballo Reservoir and the southern end of the study area.

  16. Relaxational dynamics of water molecules at protein surface

    NASA Astrophysics Data System (ADS)

    Dellerue, S.; Bellissent-Funel, M.-C.

    2000-08-01

    Relaxational dynamics of water molecules at the surface of a C-phycocyanin protein is studied by high resolution quasi-elastic neutron scattering. The neutron quasi-elastic spectra are well described by the α-relaxation process of mode coupling theory of supercooled liquids. The relaxation times of interfacial water exhibit a power law dependence on the wave vector Q. The average diffusion coefficient is 10 times lower than that of bulk water. This confirms that there is a retardation of water molecules at the protein surface which is in good agreement with the results of water at the surface of hydrophilic model systems.

  17. Population structure of harbour porpoises Phocoena phocoena in the seas around the UK and adjacent waters.

    PubMed Central

    Walton, M J

    1997-01-01

    The population structure of harbour porpoises from British and adjacent waters was studied by examining variability in a 200 bp (base pair) section of the control region of mitochondrial DNA (mtDNA) extracted from 327 animals. This region contained 20 variable sites giving rise to 24 different haplotypes. Mean nucleotide diversity between all pairs of haplotypes was 0.81% (range 0-4%). The most common haplotype occurred in 63% of the samples and was recorded in all geographical areas; several other haplotypes were present in two or more of the sampling locations. This suggests considerable historical interconnections among populations, probably through gene flow. However, there were significant differences (p < 0.05) as determined by AMOVA (Analysis of Molecular Variance, Excoffier et al. 1992), between porpoises from the northern and southern North Sea, and between the northern North Sea and the Celtic/Irish Sea. The differences were predominantly due to variation among females. This sex-related difference in population genetic structure suggests that males disperse more than females. This has important consequences for evaluating the consequences of incidental catches of porpoises by fisheries in these seas since there may be a greater impact on local populations than is implied by simple calculations of mortality. PMID:9061964

  18. Statistical summaries of streamflow in Montana and adjacent areas, water years 1900 through 2002

    USGS Publications Warehouse

    McCarthy, Peter M.

    2005-01-01

    In response to the need to have more current information about streamflow characteristics in Montana, the U.S. Geological Survey, in cooperation with the Montana Department of Environmental Quality, Confederated Salish and Kootenai Tribes, and Bureau of Land Management, conducted a study to analyze streamflow data. Updated statistical summaries of streamflow characteristics are presented for 286 streamflow-gaging sites in Montana and adjacent areas having 10 or more years of record for water years 1900 through 2002. Data include the magnitude and probability of annual low and high flow, the magnitude and probability of low flow for three seasons (March-June, July-October, and November-February), flow duration of the daily mean discharge, and the monthly and annual mean discharges. For streamflow-gaging stations where 20 percent or more of the contributing drainage basin is affected by dams or other large-scale human modification, streamflow is considered regulated. Separate streamflow characteristics are presented for the unregulated and regulated periods of record for sites with sufficient data.

  19. Distribution patterns of phytoplankton in the Changjiang River estuary and adjacent waters in spring 2009

    NASA Astrophysics Data System (ADS)

    Kong, Fanzhou; Xu, Zijun; Yu, Rencheng; Yuan, Yongquan; Zhou, Mingjiang

    2016-09-01

    The Changjiang River estuary and adjacent waters are one of the most notable regions for red tides/harmful algal blooms in China's coastal waters. In this study, phytoplankton samples were collected and analyzed during the outbreak stage of red tides in May 2009. It was found that dinoflagellates, Prorocentrum donghaiense and Karenia mikimotoi, and diatoms, Skeletonema spp. and Paralia sulcata, were the major taxa dominating the phytoplankton community. Cluster analysis, non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) was conducted on a data matrix including taxa composition and cell abundance of the phytoplankton samples. The analyses categorized the samples into three groups at a similarity level of 30%. Group I was characterized by estuarine diatoms and distributed mainly in the highly turbid estuarine region. Group II, which was dominated by the diatom Skeletonema spp. and represented the red tide of Skeletonema spp., was situated around Group I in the sea area west of 122°50'E. Group III was characterized by a high proportion of dinoflagellates and was found further offshore compared with Groups I and II. Group III was further divided into two subgroups (III-S1 and III-S2) at a similarity level of 40%. Group III-S1 was characterized by the presence of the benthic diatom P. sulcata, representing phytoplankton samples collected either from the bottom or from the sea area affected by upwelling. Group III-S2 was dominated by dinoflagellates and represented red tides formed by P. donghaiense and K. mikimotoi. A gradual change of red-tide causative species was observed from the estuary to the offshore sea area, from diatoms to armored dinoflagellates and then unarmored dinoflagellates. Environmental factors associated with each group, and thus affecting the distribution of phytoplankton and red tides, are discussed.

  20. Size, separation, structural order, and mass density of molecules packing in water and ice.

    PubMed

    Huang, Yongli; Zhang, Xi; Ma, Zengsheng; Li, Wen; Zhou, Yichun; Zhou, Ji; Zheng, Weitao; Sun, Chang Q

    2013-10-21

    The structural symmetry and molecular separation in water and ice remain uncertain. We present herewith a solution to unifying the density, the structure order and symmetry, the size (H-O length dH), and the separation (d(OO) = d(L) + d(H) or the O:H length d(L)) of molecules packing in water and ice in terms of statistic mean. This solution reconciles: i) the d(L) and the d(H) symmetrization of the O:H-O bond in compressed ice, ii) the d(OO) relaxation of cooling water and ice and, iii) the d(OO) expansion of a dimer and between molecules at water surface. With any one of the d(OO), the density ρ(g·cm⁻³), the d(L), and the d(H), as a known input, one can resolve the rest quantities using this solution that is probing conditions or methods independent. We clarified that: i) liquid water prefers statistically the mono-phase of tetrahedrally-coordinated structure with fluctuation, ii) the low-density phase (supersolid phase as it is strongly polarized with even lower density) exists only in regions consisting molecules with fewer than four neighbors and, iii) repulsion between electron pairs on adjacent oxygen atoms dictates the cooperative relaxation of the segmented O:H-O bond, which is responsible for the performance of water and ice.

  1. On the several molecules and nanostructures of water.

    PubMed

    Whitney, Cynthia Kolb

    2012-01-01

    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.

  2. On the Several Molecules and Nanostructures of Water

    PubMed Central

    Whitney, Cynthia Kolb

    2012-01-01

    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. PMID:22312305

  3. Comparison of calculated cross sections for secondary electron emission from a water molecule and clusters of water molecules by protons

    SciTech Connect

    Long, K.A.; Paretzke, H.G. )

    1991-07-15

    Double-differential cross sections for the emission of secondary electrons, as a function of emission angle and energy, from a water molecule, a cluster of water molecules, and liquid water due to proton impact have been calculated using the dielectric response function of the target material and a method which uses an integral formulation of the density-functional theory. From these double-differential cross sections, single-differential and total cross sections, and the energy loss per unit path length, have been calculated by successive integration. The results have been compared to available experimental results and, in the case of single-differential cross sections, also to empirical models. A comparison has been made between the results for the molecule and the central molecule of the cluster in order to obtain insight into how the cross sections might change in the condensed phase, namely in liquid water.

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

    PubMed

    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.

  5. A benchmark-multi-disciplinary study of the interaction between the Chesapeake Bay and adjacent waters of the Virginian Sea

    NASA Technical Reports Server (NTRS)

    Hargis, W. J., Jr.

    1981-01-01

    The social and economic importance of estuaries are discussed. Major focus is on the Chesapeake Bay and its interaction with the adjacent waters of the Virginia Sea. Associated multiple use development and management problems as well as their internal physical, geological, chemical, and biological complexities are described.

  6. 33 CFR 334.420 - Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., N.C.; danger zones for Marine Corps operations. 334.420 Section 334.420 Navigation and Navigable... REGULATIONS § 334.420 Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations. (a... date. Marine Corps Air Station Cherry Point will have a call-in number for public use to...

  7. On equilibrium structures of the water molecule

    NASA Astrophysics Data System (ADS)

    Császár, Attila G.; Czakó, Gábor; Furtenbacher, Tibor; Tennyson, Jonathan; Szalay, Viktor; Shirin, Sergei V.; Zobov, Nikolai F.; Polyansky, Oleg L.

    2005-06-01

    Equilibrium structures are fundamental entities in molecular sciences. They can be inferred from experimental data by complicated inverse procedures which often rely on several assumptions, including the Born-Oppenheimer approximation. Theory provides a direct route to equilibrium geometries. A recent high-quality ab initio semiglobal adiabatic potential-energy surface (PES) of the electronic ground state of water, reported by Polyansky et al. [Polyansky et al.Science 299, 539 (2003)] and called CVRQD here, is analyzed in this respect. The equilibrium geometries resulting from this direct route are deemed to be of higher accuracy than those that can be determined by analyzing experimental data. Detailed investigation of the effect of the breakdown of the Born-Oppenheimer approximation suggests that the concept of an isotope-independent equilibrium structure holds to about 3×10-5Å and 0.02° for water. The mass-independent [Born-Oppenheimer (BO)] equilibrium bond length and bond angle on the ground electronic state PES of water is reBO=0.95782Å and θeBO=104.485°, respectively. The related mass-dependent (adiabatic) equilibrium bond length and bond angle of H2O16 is read=0.95785Å and θead=104.500°, respectively, while those of D2O16 are read=0.95783Å and θead=104.490°. Pure ab initio prediction of J =1 and 2 rotational levels on the vibrational ground state by the CVRQD PESs is accurate to better than 0.002cm-1 for all isotopologs of water considered. Elaborate adjustment of the CVRQD PESs to reproduce all observed rovibrational transitions to better than 0.05cm-1 (or the lower ones to better than 0.0035cm-1) does not result in noticeable changes in the adiabatic equilibrium structure parameters. The expectation values of the ground vibrational state rotational constants of the water isotopologs, computed in the Eckart frame using the CVRQD PESs and atomic masses, deviate from the experimentally measured ones only marginally, especially for A0 and B0. The

  8. Adsorption mechanism of water molecule on goethite (010) surface

    NASA Astrophysics Data System (ADS)

    Xiu, Fangyuan; Zhou, Long; Xia, Shuwei; Yu, Liangmin

    2016-12-01

    Goethite widely exists among ocean sediments; it plays an important role in fixing heavy metals and adsorbing organic contaminants. So the understanding of the adsorbing process of water molecule on its surface will be very helpful to further reveal such environmental friendly processes. The configuration, electronic properties and interaction energy of water molecules adsorbed on pnma goethite (010) surface were investigated in detail by using density functional theory on 6-31G (d,p) basis set and projector- augment wave (PAW) method. The mechanism of the interaction between goethite surface and H2O was proposed. Despite the differences in total energy, there are four possible types of water molecule adsorption configurations on goethite (010) surface (Aa, Ab, Ba, Bb), forming coordination bond with surface Fe atom. Results of theoretical modeling indicate that the dissociation process of adsorbed water is an endothermic reaction with high activation energy. The dissociation of adsorbed water molecule is a proton transportation process between water's O atoms and surface. PDOS results indicate that the bonding between H2O and (010) surface is due to the overlapping of water's 2p orbitals and Fe's 3d orbitals. These results clarify the mechanism on how adsorbed water is dissociated on the surface of goethite and potentially provide useful information of the surface chemistry of goethite.

  9. Local order and mobility of water molecules around ambivalent helices.

    PubMed

    Bhattacharjee, Nicholus; Biswas, Parbati

    2011-10-27

    Water on a protein surface plays a key role in determining the structure and dynamics of proteins. Compared to the properties of bulk water, many aspects of the structure and dynamics of the water surrounding the proteins are less understood. It is interesting therefore to explore how the properties of the water within the solvation shell around the peptide molecule depend on its specific secondary structure. In this work we investigate the orientational order and residence times of the water molecules to characterize the structure, energetics, and dynamics of the hydration shell water around ambivalent peptides. Ambivalent sequences are identical sequences which display multiple secondary structures in different proteins. Molecular dynamics simulations of representative proteins containing variable helix, variable nonhelix, and conserved helix are also used to explore the local structure and mobility of water molecules in their vicinity. The results, for the first time, depict a different water distribution pattern around the conserved and variable helices. The water molecules surrounding the helical segments in variable helices are found to possess a less locally ordered structure compared to those around their corresponding nonhelical counterparts and conserved helices. The long conserved helices exhibit extremely high local residence times compared to the helical conformations of the variable helices, whereas the residence times of the nonhelical conformations of the variable helices are comparable to those of the short conserved helices. This differential pattern of the structure and dynamics of water molecules in the vicinity of conserved/variable helices may lend valuable insights for understanding the role of solvent effects in determining sequence ambivalency and help in improving the accuracy of water models used in the simulations of proteins.

  10. Amino acids in the Pearl River Estuary and adjacent waters: origins, transformation and degradation

    NASA Astrophysics Data System (ADS)

    Chen, Jianfang; Li, Yan; Yin, Kedong; Jin, Haiyan

    2004-10-01

    Two cruises were conducted in the Pearl River Estuary (PRE) and adjacent coastal waters during July 1999 and 2000 to investigate spatial variation, transformation and degradation of amino acids (AAs). Salinity, suspended sediments (SS), chl a, nutrients, dissolved organic carbon, particulate organic carbon, AAs, and hexosamines were measured and analyzed. Concentrations of particulate hydrolysable AAs (PHAAs), dissolved combined AAs and dissolved free AAs ranged from 0.41 to 12.6 μmol L-1, 1.1 to 4.0 μmol L-1 and 0.15 to 1.10 μmol L-1, respectively. AAs concentrations were low in waters of salinity <10, increased to the maximum in the estuarine and coastal plumes (salinity =10-25) and decreased beyond the coastal plume. There was a region where PHAAs were maximum, which coincided with the region of the chl a maximum and depletion of dissolved inorganic phosphorus in the coastal plume south of Hong Kong. This indicates that most of the AAs in estuarine and coastal waters were produced through phytoplankton production and AAs might be a temporary sink for inorganic nitrogen. The ratios of AAs/HAs and glucosamine/galactosamine (Glc-NH2/Gal-NH2) were on average, 26.0 and 3.8, respectively, in biogenic particulate matter (chl a >5 μg L-1 and SS<10 mg L-1), decreased in turbid particles (SS>20 mg L-1) and reached the lowest values of 5.8 and 1.4 in sediments. In particular, the ratios of AAs/HAs, Glc-NH2/Gal-NH2 were low in the upper or northwest side of the estuary where turbidity was high. This indicated that these AAs were "old", likely due to resuspension of refractory organic matter from sediments or zooplankton grazing modification and bacterial reworking as the salt wedge advanced upstream near the bottom. Apparently, the dynamics of AAs in the PRE appeared to be governed by biological production processes and estuarine circulation in the estuary. As the chl a maximum developed downstream in the estuarine and coastal plume and the salt wedge moved upstream at

  11. Autodissociation of doubly charged water molecules

    NASA Astrophysics Data System (ADS)

    Scully, S. W. J.; Wyer, J. A.; Senthil, V.; Shah, M. B.; Montenegro, E. C.

    2006-04-01

    The electron impact dissociative double-ionization cross sections for H2O between 45 and 1500eV have been measured using time of flight mass spectrometry. The energy dependence of the H++OH+ and H++O+ ion pair production cross sections indicate that Auger-like autoionization following a vacancy in the 2a1 molecular orbital is the main double ionization channel at high velocities. In contrast to expectation, these findings show that dissociation through the H2O2+ precursor state is a significant process at high collision energies. Knowledge of this process is vital as it has a direct affect on the production of important molecular species, such as H2 , during water radiolysis. Branching ratios of the various fragments produced following both autoionization and double ionization have also been obtained.

  12. Dynamics of Confined Water Molecules in Aqueous Salt Hydrates

    SciTech Connect

    Werhahn, Jasper C.; Pandelov, S.; Yoo, Soohaeng; Xantheas, Sotiris S.; Iglev, H.

    2011-04-01

    The unusual properties of water are largely dictated by the dynamics of the H bond network. A single water molecule has more H bonding sites than atoms, hence new experimental and theoretical investigations about this peculiar liquid have not ceased to appear. Confinement of water to nanodroplets or small molecular clusters drastically changes many of the liquid’s properties. Such confined water plays a major role in the solvation of macro molecules such as proteins and can even be essential to their properties. Despite the vast results available on bulk and confined water, discussions about the correlation between spectral and structural properties continue to this day. The fast relaxation of the OH stretching vibration in bulk water, and the variance of sample geometries in the experiments on confined water obfuscate definite interpretation of the spectroscopic results in terms of structural parameters. We present first time-resolved investigations on a new model system that is ideally suited to overcome many of the problems faced in spectroscopical investigation of the H bond network of water. Aqueous hydrates of inorganic salts provide water molecules in a crystal grid, that enables unambiguous correlations of spectroscopic and structural features. Furthermore, the confined water clusters are well isolated from each other in the crystal matrix, so different degrees of confinement can be achieved by selection of the appropriate salt.

  13. Roles of water molecules in trapping carbon dioxide molecules inside the interlayer space of graphene oxides.

    PubMed

    Yumura, Takashi; Yamasaki, Ayumi

    2014-05-28

    Density functional theory (DFT) calculations were employed to investigate the energetics of carbon dioxide migration within hydrated or anhydrous graphene oxides (GOs). When anhydrous GO structures contain a carbon dioxide molecule, the carbon dioxide interacts repulsively with the GO layers to increase the interlayer spacing. The repulsive electrostatic interactions are reduced by the insertion of water molecules into CO2-containing GO structures due to the occurrence of attractive water-layer interactions through hydrogen bonding. Consequently, the interlayer spacings in CO2-containing hydrated structures are shortened compared with those in the anhydrous structures. The results indicate that the intercalated water molecules have the ability to connect the GO layers in the presence of carbon dioxide. Furthermore, the DFT calculations indicated that the GO interlayer spacings, which are influenced by the intercalation of water molecules, control carbon dioxide migration within the GO layers. The importance of the interlayer spacings on the migration of carbon dioxide arises from the occurrence of repulsive interactions between CO2 and oxygen-containing groups attached on the graphene sheets. When the GO interlayer spacings are short due to the presence of intercalated water molecules, the repulsive interactions between carbon dioxide and the GO layers are strong enough to prevent CO2 from migrating from its original position. Such repulsive interactions do not occur during the migration of CO2 within anhydrous GO structures because of the relatively longer interlayer spacing. Accordingly, CO2 migrates within anhydrous GO with a less significant barrier, indicating that carbon dioxide molecules are easily released from the GO.

  14. Anisotropic diffusion of water molecules in hydroxyapatite nanopores

    NASA Astrophysics Data System (ADS)

    Prakash, Muthuramalingam; Lemaire, Thibault; Caruel, Matthieu; Lewerenz, Marius; de Leeuw, Nora H.; Di Tommaso, Devis; Naili, Salah

    2017-03-01

    New insights into the dynamical properties of water in hydroxyapatite (HAP) nanopores, a model system for the fluid flow within nanosize spaces inside the collagen-apatite structure of bone, were obtained from molecular dynamics simulations of liquid water confined between two parallel HAP surfaces of different sizes (20 Å ≤ H ≤ 240 Å). Calculations were conducted using a core-shell interatomic potential for HAP together with the extended simple point charge model for water. This force field gives an activation energy for water diffusion within HAP nanopores that is in excellent agreement with available experimental data. The dynamical properties of water within the HAP nanopores were quantified in terms of the second-order water diffusion tensor. Results indicate that water diffuses anisotropically within the HAP nanopores, with the solvent molecules moving parallel to the surface twice as fast as the perpendicular direction. This unusual dynamic behaviour is linked to the strong polarizing effect of calcium ions, and the synergic interactions between the water molecules in the first hydration layer of HAP with the calcium, hydroxyl, and phosphate ions, which facilitates the flow of water molecules in the directions parallel to the HAP surface.

  15. Fish assemblage structure in the hypoxic zone in the Changjiang (Yangtze River) estuary and its adjacent waters

    NASA Astrophysics Data System (ADS)

    Shan, Xiujuan; Jin, Xianshi; Yuan, Wei

    2010-05-01

    Fish assemblage structure in the hypoxic zone in the Changjiang (Yangtze River) estuary and its adjacent waters were analyzed based on data from bottom trawl surveys conducted on the R/V Beidou in June, August and October 2006. Four fish assemblages were identified in each survey using two-way indicator species analysis (TWIA). High fish biomass was found in the northern part, central part and coastal waters of the survey area; in contrast, high fish diversity was found in the southern part of the survey area and the Changjiang estuary outer waters. Therefore, it is difficult to maintain high fishery production when high fish diversity is evenly distributed in the fish community. Fish became smaller and fish size spectra tended to be narrower because of fish species variations and differences in growth characteristics. Fish diversity increased, the age to maturity was reduced and some migrant species were not collected in the surveys. Fish with low economic value, small size, simple age structure and low tropic level were predominant in fish assemblages in the Changjiang estuary and its adjacent waters. The lowest hypoxic value decreased in the Changjiang estuary and its adjacent waters.

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

    SciTech Connect

    Zhu, Chongqin; Li, Hui; Meng, Sheng

    2014-11-14

    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.

  17. Rotovibrational states of the water molecule on the sun.

    PubMed

    Leite, Bruno S; Bastos, Cristiano C; Pavão, Antonio C

    2016-12-01

    The infrared spectrum of water observed in sunspots is complex and dense, with bands separated by approximately 0.01 cm(-1). For top asymmetrical molecules, there is no theoretical approach that allows for the calculation of rotovibrational energy with such precision. Experimentally derived rotovibracional energy levels of water at high temperatures combined with variational calculations have been used for the band assignments. These energy levels are employed to refine the analysis of a small portion of the infrared absorption spectrum. Such procedure has allowed for the identification of additional 55 bands to the 70 already identified as rotovibrational transitions of the water molecule. Our new assignments, which include pure and cross transitions, offer additional evidence of the existence of water on the sun, but above all they illustrate the complexity of the solar spectrum that involves states with higher levels of rotational excitation. Given the conditions on the sun, more molecules of water would occur in excited electronic states, which include apolar and paramagnetic states, generating intense bands in the spectrum. Since there is an analytical solution for the rotovibrational transitions of linear molecules, we were able to identify 16 bands relative to the excited electronic states (1)B2 and (3)A1 in the sunspot spectrum. Density functional B3LYP/AUG-cc-pVTZ calculations of the electric and magnetic dipole are employed to discuss some consequences of the presence of excited states of water in the dynamics of sunspots and solar magnetic field.

  18. Unprecedentedly rapid transport of single-file rolling water molecules

    NASA Astrophysics Data System (ADS)

    Qiu, Tong; Huang, Ji-Ping

    2015-10-01

    The realization of rapid and unidirectional single-file water-molecule flow in nanochannels has posed a challenge to date. Here, we report unprecedentedly rapid unidirectional single-file water-molecule flow under a translational terahertz electric field, which is obtained by developing a Debye doublerelaxation theory. In addition, we demonstrate that all the single-file molecules undergo both stable translation and rotation, behaving like high-speed train wheels moving along a railway track. Independent molecular dynamics simulations help to confirm these theoretical results. The mechanism involves the resonant relaxation dynamics of H and O atoms. Further, an experimental demonstration is suggested and discussed. This work has implications for the design of high-efficiency nanochannels or smaller nanomachines in the field of nanotechnology, and the findings also aid in the understanding and control of water flow across biological nanochannels in biology-related research.

  19. SPAM: A Simple Approach for Profiling Bound Water Molecules.

    PubMed

    Cui, Guanglei; Swails, Jason M; Manas, Eric S

    2013-12-10

    A method that identifies the hydration shell structure of proteins and estimates the relative free energies of water molecules within that hydration shell is described. The method, which we call "SPAM" (maps spelled in reverse), utilizes explicit solvent molecular dynamics (MD) simulations to capture discrete hydration sites at the water-protein interface and computes a local free energy measure from the distribution of interaction energies between water and the environment at a specific site. SPAM is able to provide a qualitative estimate of the thermodynamic profile of bound water molecules that correlates nicely with well-studied structure-activity relationships and observed binding "hot spots". This is demonstrated in retrospective analyses of HIV1 protease and hen egg white lysozyme, where the effects of water displacement and solvent binding have been studied extensively. The simplicity and effectiveness of SPAM allow for prospective application during the drug discovery process.

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

    PubMed

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

    2015-03-28

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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. Structures of water molecules in carbon nanotubes under electric fields

    SciTech Connect

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

    2015-03-28

    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.

  3. [Ecological niche breadth and niche overlap of dominant species of fish assemblage in Yangtze river estuary and its adjacent waters].

    PubMed

    Li, Xian-sen; Yu, Zhen-hai; Sun, Shan; Jin, Xian-shi

    2013-08-01

    Based on the fishery resources data from the bottom trawl surveys conducted on the R/V Beidou in the Yangtze River estuary and its adjacent waters in June, August and October of 2006, the index of relative importance (IRI) was measured to determine the dominant species of fish assemblage, and the niche indicators and their seasonal variations of the dominant species were analyzed. A total of 10 dominant species in the 3 survey cruises were recorded, which were divided into two groups by the Bray-curtis similarity clustering and non-metric multidimensional scaling (MDS) analysis, with a significant seasonal variation of niche breadth and niche overlap. One group included Engraulis japonicus, Champsodon capensis, and Acropoma japonicum, whose niche breadth and niche overlap were larger in summer than in autumn, with a migration from the Yangtze River estuary and its adjacent waters to outer deeper waters, while the other group included Trichiurus haumela, Chaeturichthys stigmatias, Apogon lineatus, Larimichthys polyactis, Psenopsis anomala, Argyrosomus argentatus, and Benthosema pterotum, whose niche breadth and niche overlap were larger in autumn than in summer, with a reverse migration from southern Yellow Sea and northern East China Sea to the Yangtze River estuary and its adjacent waters. The different migration direction of the two groups was related to their ecological habits and environmental factors.

  4. An interdisciplinary study of the estuarine and coastal oceanography of Block Island Sound and adjacent New York coastal waters

    NASA Technical Reports Server (NTRS)

    Yost, E. (Principal Investigator)

    1972-01-01

    The author has identified the following significant results. The synoptic repetitive coverage of the multispectral imagery from the ERTS-1 satellite, when photographically reprocessed using the state-of-the-art techniques, has given indication of spectral differences in Block Island and adjacent New England waters which were heretofore unknown. Of particular interest was the possible detection of relatively small amounts of phytoplankton prior to the occurrence of the red tide in Massachusetts waters. Preparation of spatial and temporal hydrographic charts using ERTS-1 imagery and ground truth analysis will hopefully determine the environmental impact on New York coastal waters.

  5. Visualizing Water Molecules in Transmembrane Proteins Using Radiolytic Labeling Methods

    SciTech Connect

    Orban, T.; Gupta, S; Palczewski, K; Chance, M

    2010-01-01

    Essential to cells and their organelles, water is both shuttled to where it is needed and trapped within cellular compartments and structures. Moreover, ordered waters within protein structures often colocalize with strategically placed polar or charged groups critical for protein function, yet it is unclear if these ordered water molecules provide structural stabilization, mediate conformational changes in signaling, neutralize charged residues, or carry out a combination of all these functions. Structures of many integral membrane proteins, including G protein-coupled receptors (GPCRs), reveal the presence of ordered water molecules that may act like prosthetic groups in a manner quite unlike bulk water. Identification of 'ordered' waters within a crystalline protein structure requires sufficient occupancy of water to enable its detection in the protein's X-ray diffraction pattern, and thus, the observed waters likely represent a subset of tightly bound functional waters. In this review, we highlight recent studies that suggest the structures of ordered waters within GPCRs are as conserved (and thus as important) as conserved side chains. In addition, methods of radiolysis, coupled to structural mass spectrometry (protein footprinting), reveal dynamic changes in water structure that mediate transmembrane signaling. The idea of water as a prosthetic group mediating chemical reaction dynamics is not new in fields such as catalysis. However, the concept of water as a mediator of conformational dynamics in signaling is just emerging, because of advances in both crystallographic structure determination and new methods of protein footprinting. Although oil and water do not mix, understanding the roles of water is essential to understanding the function of membrane proteins.

  6. Water molecules in clay minerals: Thermodynamic functions and hydration

    NASA Astrophysics Data System (ADS)

    Gailhanou, Helène; Amouric, Marc; Olives, Juan; Rogez, Jacques; van Miltenburg, J. C.; van der Berg, G. J. K.; de Weireld, G.; Gaucher, E.; Blanc, P.

    2010-05-01

    Thermodynamic functions and adsorption of water molecules are very important properties for clay minerals. Smectite MX-80 and mixed-layer illite-smectite ISCz-1 were selected. They were first carefully characterized (HRTEM with EDX analysis), revealing original results. Then, the thermodynamic properties of water in clay were obtained by (i) comparison of the thermodynamic properties of anhydrous and hydrated minerals, between 0 and 350 K (adiabatic calorimetry, solution isothermal calorimetry), and (ii) water vapor adsorption isotherms, between 300 and 380 K (magnetic suspension thermobalance). Solution isothermal calorimetry is used to determine the enthalpies of formation of the minerals (1 bar and 298 K). Comparison of the results, for the anhydrous and the hydrated minerals, leads to the enthalpies of hydration at 298 K. Adiabatic calorimetry measurements give the heat capacities of the minerals from 5 to 350 K. Entropies, enthalpies of formation and Gibbs free energies of formation, for the anhydrous and the hydrated minerals, and then, entropies of hydration, enthalpies of hydration and Gibbs free energies of hydration, between 0 and 350 K, are finally obtained. Comparison of two close hydration states leads to the entropy, the enthalpy and the Gibbs free energy of the adsorption reaction: H2O free - H2O adsorbed. The Cp(T) curve, for the heat capacity of water in clay - i.e., the difference between the heat capacities of the hydrated and the anhydrous minerals -, shows that water in clay is a glass at low temperature, undergoes one or two continuous glass transitions between 150 and 270 K, and behaves as free liquid water above 273 K. The two glass transitions might correspond to two types of water molecules: (i) first adsorbed water molecules, bound to the interlayer cations of the clay mineral; (ii) last adsorbed water molecules, not bound to the interlayer cations. In addition, water vapor adsorption isotherms are obtained from 298 to 378 K (magnetic

  7. Assessment of water resources in lead-zinc mined areas in Cherokee County, Kansas, and adjacent areas

    USGS Publications Warehouse

    Spruill, T.B.

    1984-01-01

    A study was conducted to evaluate water-resource problems related to abandoned lead and zinc mines in Cherokee County, and adjacent areas in Oklahoma and Missouri. Discontinuities and perforations, which were produced by mining in the confining shale west of the Pennsylvanian-Mississippian geologic contact, have created artificial groundwater recharge and discharge areas. Abandoned wells and drill holes present the greatest contamination hazard to water supplies in the deep aquifer. There is a potential for downward movement from the shallow to the deep aquifer throughout the study area, with greatest potential in Ottawa County, Oklahoma. Principal effects of abandoned mines on groundwater quality are lowered pH and increased concentrations of sulfate and trace metals of water in the mines. No conclusive evidence of lateral migration of contaminated mine water from the mines into the water-supply wells adjacent to the mines was found. Analyses of water from the deep aquifer did not indicate trace-metal contamination. The effects of abandoned mines on streamwater quality are most severe in Short Creek and Tar Creek. Increased concentrations of zinc and manganese were observed in the Spring River below Short Creek Kansas. (USGS)

  8. A transferable classical potential for the water molecule.

    PubMed

    Baranyai, András; Kiss, Péter T

    2010-10-14

    We developed a new model for the water molecule which contains only three Gaussian charges. Using the gas-phase geometry the dipole moment of the molecule matches, the quadrupole moment closely approximates the experimental values. The negative charge is connected by a harmonic spring to its gas-phase position. The polarized state is identified by the equality of the intermolecular electrostatic force and the spring force acting on the negative charge. In each timestep the instantaneous position of the massless negative charge is determined by iteration. Using the technique of Ewald summation, we derived expressions for the potential energy, the forces, and the pressure for Gaussian charges. The only properties to be fitted are the half-width values of the Gaussian charge distributions and the parameters of the nonelectrostatic repulsion-attraction potential. We determined the properties of gas-phase clusters up to six molecules, the internal energy and density of ambient water and hexagonal ice. We calculated the equilibrium density of ice VII as a function of pressure. As an additional test, we calculated the pair-correlation function, the isotherm compressibility, the heat capacity, and the self-diffusion coefficients for ambient water. As far as we know, this is the first classical model of water which is able to estimate both ends of the phase diagram, the high pressure ice VII, and the gas clusters of water with excellent accuracy.

  9. Reorientional dynamics of water molecules in anionic hydration shells

    PubMed Central

    Laage, Damien; Hynes, James T.

    2007-01-01

    Water molecule rotational dynamics within a chloride anion's first hydration shell are investigated through simulations. In contrast to recent suggestions that the ion's hydration shell is rigid during a water's reorientation, we find a labile hydration sphere, consistent with previous assessments of chloride as a weak structure breaker. The nondiffusive reorientation mechanism found involves a hydrogen-bond partner switch with a large amplitude angular jump and the water's departure from the anion's shell. An analytic extended jump model accounts for the simulation results, as well as available NMR and ultrafast spectroscopic data, and resolves the discrepancy between them. PMID:17581877

  10. Water-quality, water-level, and lake-bottom-sediment data collected from the defense fuel supply point and adjacent properties, Hanahan, South Carolina, 1990-96

    USGS Publications Warehouse

    Petkewich, M.D.; Vroblesky, D.A.; Robertson, J.F.; Bradley, P.M.

    1997-01-01

    A 9-year scientific investigation to determine the potential for biore-mediation of ground-water contamination and to monitor the effectiveness of an engineered bioremediation system located at the Defense Fuel Supply Point and adjacent properties in Hanahan, S.C., has culminated in the collection of abundant water-quality and water-level data.This report presents the analytical results of the study that monitored the changes in surface- and ground-water quality and water-table elevations in the study area from December 1990 to January 1996. This report also presents analytical results of lake-bottom sediments collected in the study area.

  11. Chemical Interactions of Uranium in Water, Sediments, and Plants Along a Watershed Adjacent to the Abandoned Jackpile Mine

    NASA Astrophysics Data System (ADS)

    Blake, J.; De Vore, C. L.; Avasarala, S.; Ali, A.; Roldan, C.; Bowers, F.; Spilde, M.; Artyushkova, K.; Cerrato, J.

    2015-12-01

    The chemical interactions, mobility, and plant uptake of uranium (U) near abandoned mine wastes was investigated along the Rio Paguate, adjacent to the Jackpile Mine, located in Laguna Pueblo, New Mexico. Elevated U concentrations in surface water adjacent to mine waste range from 30 to 710 μg/L seasonally and decrease to 5.77 to 10.0 μg/L at a wetland 4.5 kilometers downstream of the mine. Although U concentrations in stream water are elevated, aqua regia acid digestions performed on co-located stream bed and stream bank sediments reveal that there is limited U accumulation on sediments along the reach between the mine and wetland, with most sediment concentrations being near the 3 mg/kg crustal average. However, U concentrations in sediments in the wetland are 4 times the background concentrations in the area. Individual results from salt cedar roots, stems, and leaves collected along the river transect show higher U concentrations in the roots adjacent to the mine waste (20 and 55 mg/kg) and lower in the stems and leaves. Translocation values calculated below 1 are evident in many of the plant samples, suggesting that U root to shoot translocation is minimal and U is accumulating in the roots. Concentrations of U in salt cedar roots from downstream of the mine waste decrease to 15 mg/kg. X-ray photoelectron spectroscopy analysis on sediment samples adjacent to the mine waste show a 75:25% ratio of Fe(III) to Fe(II), which can have an effect on adsorption properties. Electron microprobe results suggest that the ore in this area is present as a uranium-phosphate phase. Our results suggest that dilution, uptake by plants, and U sorption to wetland sediments are the dominant factors that help to decrease the U concentrations downstream of the mine.

  12. Potentiometric surface of Floridan aquifer, Southwest Florida Water Management District and adjacent areas, September 1977

    USGS Publications Warehouse

    Ryder, P.D.; Mills, L.R.; Laughlin, C.P.

    1978-01-01

    A potentiometric-surface map of the Southwest Florida Water Management District depicts the annual high water-level period. Potentiometric levels increased 15 to 30 feet between May 1977 and September 1977 in the citrus and farming sections of southeastern Hillsborough, northern Hardee, and southwestern Polk Counties. These areas are widely affected by pumpage for irrigation and have the greatest range in water-level fluctuations between the low and high water-level periods. Water-level rises in coastal, northern, and southern areas of the Water Management District ranged from 0 to 15 feet. (Woodard-USGS)

  13. Variational path integral molecular dynamics study of a water molecule

    NASA Astrophysics Data System (ADS)

    Miura, Shinichi

    2013-08-01

    In the present study, a variational path integral molecular dynamics method developed by the author [Chem. Phys. Lett. 482, 165 (2009)] is applied to a water molecule on the adiabatic potential energy surface. The method numerically generates an exact wavefunction using a trial wavefunction of the target system. It has been shown that even if a poor trial wavefunction is employed, the exact quantum distribution is numerically extracted, demonstrating the robustness of the variational path integral method.

  14. Potentiometric surface of the Floridan Aquifer, Southwest Florida Water Management District and adjacent areas, September 1978

    USGS Publications Warehouse

    Wolansky, R.M.; Mills, L.R.; Woodham, W.M.; Laughlin, C.P.

    1978-01-01

    A September 1978 potentiometric-surface map depicts the annual high water-level period of the Floridan aquifer in the Southwest Florida Management District. Potentiometric levels increased 10 to 25 feet between May 1978 and September 1978, in the citrus and farming sections of southern Hillsborough, northern Hardee, southwestern Polk and Manatee Counties. These areas are widely affected by pumping for irrigation and have the greatest fluctuations in water-levels between the low and high water-level periods. Water-level rises in coastal, northern and southern areas of the Water Management District ranged from 0 to 10 feet. (Woodard-USGS)

  15. Interaction Of Water Molecules With SiC(001) Surfaces

    SciTech Connect

    Cicero, G; Catellani, A; Galli, G

    2004-08-10

    We have investigated the interaction of water molecules with the polar Si- and C- terminated surfaces of cubic Silicon Carbide by means of ab initio molecular dynamics simulations at finite temperature. Different water coverages were considered, from {1/4} to a complete monolayer. Irrespective of coverage, we find that water dissociates on the silicon terminated surfaces, leading to important changes in both its structural and electronic properties. On the contrary, the carbon terminated surface remains inert when exposed to water. We propose experiments to reveal the ionic and electronic structure of wet Si-terminated surfaces predicted by our calculations, which at full coverage are notably different from those of hydrated Si(001) substrates. Finally, we discuss the implications of our results for SiC surface functionalization.

  16. Sediment load from major rivers into Puget Sound and its adjacent waters

    USGS Publications Warehouse

    Czuba, Jonathan A.; Magirl, Christopher S.; Czuba, Christiana R.; Grossman, Eric E.; Curran, Christopher A.; Gendaszek, Andrew S.; Dinicola, Richard S.

    2011-01-01

    Each year, an estimated load of 6.5 million tons of sediment is transported by rivers to Puget Sound and its adjacent waters—enough to cover a football field to the height of six Space Needles. This estimated load is highly uncertain because sediment studies and available sediment-load data are sparse and historically limited to specific rivers, short time frames, and a narrow range of hydrologic conditions. The largest sediment loads are carried by rivers with glaciated volcanoes in their headwaters. Research suggests 70 percent of the sediment load delivered to Puget Sound is from rivers and 30 percent is from shoreline erosion, but the magnitude of specific contributions is highly uncertain. Most of a river's sediment load occurs during floods.

  17. A Revision of the Stylasteridae (Cnidaria, Hydrozoa, Filifera) from Alaska and Adjacent Waters

    PubMed Central

    Cairns, Stephen D.; Lindner, Alberto

    2011-01-01

    Abstract The stylasterid fauna of Alaska is revised, consisting of the description or redescription and illustration of 21 species, one additional subspecies, and a geographically adjacent species: Stylaster venustus. Six new species and one new subspecies are described: Errinopora fisheri, Errinopora undulata, Errinopora disticha, Errinopora dichotoma, Stylaster crassiseptum, Stylaster repandus, and Stylaster parageus columbiensis. Four subspecies are raised to species rank: Stylaster leptostylus, Stylaster trachystomus, Stylaster parageus, and Distichopora japonica, and five species and one subspecies were synonymized. A dichotomous key to the Errinopora species and tabular keys to the Errinopora and Alaskan Stylaster species are provided. The focus of the study was on the stylasterids from Alaska, primarily those from the diverse Aleutian Islands, but also including records from British Columbia. This is the first revisionary work on this fauna since the seminal report by Fisher in 1938. PMID:22303109

  18. [Assessment of ecosystem energy flow and carrying capacity of swimming crab enhancement in the Yellow River estuary and adjacent waters].

    PubMed

    Lin Qun; Wang, Jun; Li, Zhong-yi; Wu, Qiang

    2015-11-01

    Stock enhancement is increasingly proved to be an important measure of the fishery resources conservation, and the assessment of carrying capacity is the decisive factor of the effects of stock enhancement. Meanwhile, the variations in the energy flow patterns of releasing species and ecosystem were the basis for assessing carrying capacity of stock enhancement. So, in the present study, based on the survey data collected from the Yellow River estuary and adjacent waters during 2012-2013, three Ecopath mass-balance models were established in June, August and October, and the variations in ecosystem energy flow in these months were analyzed, as well as the assessment of carrying capacity of swimming crab enhancement. The energy flow mainly concentrated on trophic level I-III in Yellow River estuary and adjacent waters, and was relatively less on trophic level IV or above. The system flow proportion on the trophic level I was the highest in June, and was the lowest in August. The highest system flow proportion on the trophic level II was found in August, and the lowest in June. The relative and absolute energy flow of swimming crab mainly concentrated on the trophic level III, and the mean trophic level of swimming crab among June, August and October were 3.28. Surplus production was relatively higher in Yellow River estuary and adjacent waters, the highest value was found in June, and the lowest value in August. The ratios of total primary production/total respiration (TPP/TR) were 5.49, 2.47 and 3.01 in June, August and October, respectively, and the ratios of total primary production/total biomass (TPP/B) were 47.61, 33.30 and 29.78, respectively. Combined with the low Finn' s cycling index (FCI: 0.03-0.06), these changes indicated that the Yellow River estuary ecosystem was at an early development stage with higher vulnerability. The energy conversion efficiency of system was from 7.3% to 11.5%, the mean trophic levels of the catch were 3.23, 2.97 and 2.82 in

  19. Ground Water in Kilauea Volcano and Adjacent Areas of Mauna Loa Volcano, Island of Hawaii

    USGS Publications Warehouse

    Takasaki, Kiyoshi J.

    1993-01-01

    About 1,000 million gallons of water per day moves toward or into ground-water bodies of Kilauea Volcano from the lavas of Mauna Loa Volcano. This movement continues only to the northern boundaries of the east and southwest rift zones of Kilauea, where a substantial quantity of ground water is deflected downslope to other ground-water bodies or to the ocean. In the western part of Kilauea, the kaoiki fault system, which parallels the southwest rift zone, may be the main barrier to ground-water movement. The diversion of the ground water is manifested in the western part of Kilauea by the presence of large springs at the shore end of the Kaoiki fault system, and in the eastern part by the apparently large flow of unheated basal ground water north of the east rift zone. Thus, recharge to ground water in the rift zones of Kilauea and to the areas to the south of the rift zones may be largely by local rainfall. Recharge from rainfall for all of Kilauea is about 1,250 million gallons per day. Beneath the upper slopes of the Kilauea rift zones, ground-water levels are 2,000 feet or more above mean sea level, or more than 1,000 feet below land surface. Ground-water levels are at these high altitudes because numerous and closely spaced dikes at depth in the upper slopes impound the ground water. In the lower slopes, because the number of dikes decreases toward the surface, the presence of a sufficient number of dikes capable of impounding ground water at altitudes substantially above sea level is unlikely. In surrounding basal ground-water reservoirs, fresh basal ground water floats on seawater and, through a transition zone of mixed freshwater and seawater, discharges into the sea. The hydraulic conductivity of the dike-free lavas ranges from about 3,000 to about 7,000 feet per day. The conductivity in the upper slopes of the rift ranges from about 5 to 30 feet per day and that of the lower slopes of the east rift zone was calculated at about 7,000 feet per day. The

  20. Bond-based linear indices of the non-stochastic and stochastic edge-adjacency matrix. 1. Theory and modeling of ChemPhys properties of organic molecules.

    PubMed

    Marrero-Ponce, Yovani; Martínez-Albelo, Eugenio R; Casañola-Martín, Gerardo M; Castillo-Garit, Juan A; Echevería-Díaz, Yunaimy; Zaldivar, Vicente Romero; Tygat, Jan; Borges, José E Rodriguez; García-Domenech, Ramón; Torrens, Francisco; Pérez-Giménez, Facundo

    2010-11-01

    Novel bond-level molecular descriptors are proposed, based on linear maps similar to the ones defined in algebra theory. The kth edge-adjacency matrix (E(k)) denotes the matrix of bond linear indices (non-stochastic) with regard to canonical basis set. The kth stochastic edge-adjacency matrix, ES(k), is here proposed as a new molecular representation easily calculated from E(k). Then, the kth stochastic bond linear indices are calculated using ES(k) as operators of linear transformations. In both cases, the bond-type formalism is developed. The kth non-stochastic and stochastic total linear indices are calculated by adding the kth non-stochastic and stochastic bond linear indices, respectively, of all bonds in molecule. First, the new bond-based molecular descriptors (MDs) are tested for suitability, for the QSPRs, by analyzing regressions of novel indices for selected physicochemical properties of octane isomers (first round). General performance of the new descriptors in this QSPR studies is evaluated with regard to the well-known sets of 2D/3D MDs. From the analysis, we can conclude that the non-stochastic and stochastic bond-based linear indices have an overall good modeling capability proving their usefulness in QSPR studies. Later, the novel bond-level MDs are also used for the description and prediction of the boiling point of 28 alkyl-alcohols (second round), and to the modeling of the specific rate constant (log k), partition coefficient (log P), as well as the antibacterial activity of 34 derivatives of 2-furylethylenes (third round). The comparison with other approaches (edge- and vertices-based connectivity indices, total and local spectral moments, and quantum chemical descriptors as well as E-state/biomolecular encounter parameters) exposes a good behavior of our method in this QSPR studies. Finally, the approach described in this study appears to be a very promising structural invariant, useful not only for QSPR studies but also for similarity

  1. Sticking of Molecules on Nonporous Amorphous Water Ice

    NASA Astrophysics Data System (ADS)

    He, Jiao; Acharyya, Kinsuk; Vidali, Gianfranco

    2016-05-01

    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 H2, D2, N2, O2, CO, CH4, and CO2 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.

  2. The spontaneous synchronized dance of pairs of water molecules

    SciTech Connect

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

    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.

  3. Water quality at and adjacent to the south Dade County solid-waste disposal facility, Florida

    USGS Publications Warehouse

    McKenzie, D.J.

    1983-01-01

    A water-quality reconnaissance was conducted at the south Dade County solid-waste landfill near Goulds, Florida, from December 1977 through August 1978. The landfill is located directly on the unconfined Biscayne aquifer, which, in the study area, is affected by saltwater intrusion. Water samples collected from six monitor well sites at two depths and four surface-water sites were analyzed to determine the chemical, physical, and biological conditions of the ground water and surface water of the study area. Results indicated that water quality beneath the landfill was highly variable with location and depth. Leachate was generally more evident in the shallow wells and during the dry-season sampling, but was greatly diluted and dispersed in the deep wells and during the wet season. High concentrations of contaminants were generated primarily in areas of the landfill with the most recent waste deposits. Chloride (limited to the shallow wells and the dry season), alkalinity, ammonia, iron, manganese, lead, phosphorus, and organic nitrogen indicate leachate contamination of the aquifer. Water-quality characteristics in the surface waters were generally only slightly above background levels. (USGS)

  4. Emergency ground-water supplies in the Seattle-Tacoma urban complex and adjacent areas, Washington

    USGS Publications Warehouse

    Foxworthy, B.L.

    1972-01-01

    Urban areas that are supplied from surface-water sources are especially vulnerable to major disruption of their water supplies. Such disruption could result from natural disasters such as earthquakes, floods, or landslides or from such other causes as dam failures fallout of radioactive material or other toxic substance from the atmosphere or other toxic substances from the atmosphere or direct introduction (either accidental or deliberate) of any substance that would render the water unfit for use. Prolonged disruption of public water supplies not only causes personal hardships but also endangers health and safety unless suitable alternative emergency supplies can be provided. The degree of hardship and danger generally increases in direct relation to the population density. Ground water because it occurs beneath protective soil and rock materials is less subject to sudden major contamination than are surface-water bodies. For this reason and also because of its widespread availability in the Puget Sound region ground water is especially desireable as a sources of emergency supplies for drinking or other uses requiring water of good quality. In much of the area existing wells would be suitable as safe sources of emergency supplies.

  5. Ground-water resources in the tri-state region adjacent to the Lower Delaware River

    USGS Publications Warehouse

    Barksdale, Henry C.; Greenman, David W.; Lang, Solomon Max; Hilton, George Stockbridge; Outlaw, Donald E.

    1958-01-01

    The maximum beneficial utilization of the ground-water resources cannot be accomplished in haphazard fashion. It must be planned and controlled on the basis of sound, current information about the hydrology of the various aquifers. Continued and, in some areas, intensified investigations of the ground-water resources of the region should form the basis for such planning and control.

  6. Geometry-dependent distributed polarizability models for the water molecule

    SciTech Connect

    Loboda, Oleksandr; Ingrosso, Francesca; Ruiz-López, Manuel F.; Millot, Claude; Szalewicz, Krzysztof

    2016-01-21

    Geometry-dependent distributed polarizability models have been constructed by fits to ab initio calculations at the coupled cluster level of theory with up to noniterative triple excitations in an augmented triple-zeta quality basis set for the water molecule in the field of a point charge. The investigated models include (i) charge-flow polarizabilities between chemically bonded atoms, (ii) isotropic or anisotropic dipolar polarizabilities on oxygen atom or on all atoms, and (iii) combinations of models (i) and (ii). For each model, the polarizability parameters have been optimized to reproduce the induction energy of a water molecule polarized by a point charge successively occupying a grid of points surrounding the molecule. The quality of the models is ascertained by examining their ability to reproduce these induction energies as well as the molecular dipolar and quadrupolar polarizabilities. The geometry dependence of the distributed polarizability models has been explored by changing bond lengths and HOH angle to generate 125 molecular structures (reduced to 75 symmetry-unique ones). For each considered model, the distributed polarizability components have been fitted as a function of the geometry by a Taylor expansion in monomer coordinate displacements up to the sum of powers equal to 4.

  7. Oceanic distribution and life cycle of Calanus species in the Norwegian Sea and adjacent waters

    NASA Astrophysics Data System (ADS)

    Broms, Cecilie; Melle, Webjørn; Kaartvedt, Stein

    2009-10-01

    The distribution and demography of Calanus finmarchicus, C. glacialis and C. hyperboreus were studied throughout their growth season on a basin scale in the Norwegian Sea using ordination techniques and generalized additive models. The distribution and demographic data were related to the seasonal development of the phytoplankton bloom and physical characteristics of water masses. The resulting quantified relationships were related to knowledge on life cycle and adaptations of Calanus species. C. finmarchicus was the numerically dominant Calanus species in Coastal, Atlantic and Arctic waters, showing strong association with both Atlantic and Arctic waters. C. hyperboreus and C. glacialis were associated with Arctic water; however, C. glacialis was occasionally observed in the Norwegian Sea and is probably an expatriate advected into the area from various origins. Demography indicated one generation per year of C. finmarchicus, a two-year life cycle of C. hyperboreus, and both one- and two-year life cycles for C. glacialis in the water masses where they were most abundant. For the examined Calanus species, young copepodites of the new generation seemed to be tuned to the phytoplankton bloom in their main water mass. The development of C. finmarchicus was delayed in Arctic water, and mis-match between feeding stages and the phytoplankton bloom may reduce survival and reproductive success of C. finmarchicus in Arctic water. Based on low abundances of C. hyperboreus CI-III in Atlantic water and main recruitment to CI prior to the phytoplankton bloom, we suggest that reproduction of C. hyperboreus in Atlantic water is not successful.

  8. Water resources of the Tulalip Indian Reservation and adjacent area, Snohomish County, Washington, 2001-03

    USGS Publications Warehouse

    Frans, Lonna M.; Kresch, David L.

    2004-01-01

    This study was undertaken to improve the understanding of water resources of the Tulalip Plateau area, with a primary emphasis on the Tulalip Indian Reservation, in order to address concerns of the Tulalip Tribes about the effects of current and future development, both on and off the Reservation, on their water resources. The drinking-water supply for the Reservation comes almost entirely from ground water, so increasing population will continue to put more pressure on this resource. The study evaluated the current state of ground- and surface-water resources and comparing results with those of studies in the 1970s and 1980s. The study included updating descriptions of the hydrologic framework and ground-water system, determining if discharge and base flow in streams and lake stage have changed significantly since the 1970s, and preparing new estimates of the water budget. The hydrogeologic framework was described using data collected from 255 wells, including their location and lithology. Data collected for the Reservation water budget included continuous and periodic streamflow measurements, micrometeorological data including daily precipitation, temperature, and solar radiation, water-use data, and atmospheric chloride deposition collected under both wet- and dry-deposition conditions to estimate ground-water recharge. The Tulalip Plateau is composed of unconsolidated sediments of Quaternary age that are mostly of glacial origin. There are three aquifers and two confining units as well as two smaller units that are only localized in extent. The Vashon recessional outwash (Qvr) is the smallest of the three aquifers and lies in the Marysville Trough on the eastern part of the study area. The primary aquifer in terms of use is the Vashon advance outwash (Qva). The Vashon till (Qvt) and the transitional beds (Qtb) act as confining units. The Vashon till overlies Qva and the transitional beds underlie Qva and separate it from the undifferentiated sediments (Qu

  9. Adjacency effects in satellite radiometric products from coastal waters: a theoretical analysis for the northern Adriatic Sea.

    PubMed

    Bulgarelli, Barbara; Kiselev, Viatcheslav; Zibordi, Giuseppe

    2017-02-01

    Biases induced by land perturbations in satellite-derived water-leaving radiance are theoretically estimated for typical observation conditions in a coastal area of the northern Adriatic Sea hosting the Aqua Alta Oceanographic Tower (AAOT) validation site. Two different correction procedures are considered: not deriving (AC-1) or alternatively deriving (AC-2) the atmospheric properties from the remote sensing data. In both cases, biases due to adjacency effects largely increase by approaching the coast and with the satellite viewing angle. Conversely, the seasonal and spectral dependence of biases significantly differ between AC-1 and AC-2 schemes. For AC-1 schemes average biases are within ±5% throughout the transect at yellow-green wavelengths, but at the coast they can reach -21% and 34% at 412 and 670 nm, respectively, and exceed 100% at 865 nm. For AC-2 schemes, adjacency effects at those wavelengths from which atmospheric properties are inferred add significant perturbations. For the specific case of a correction scheme determining the atmospheric properties from the near-infrared region and by adopting a power-law spectral extrapolation of adjacency perturbations on the derived atmospheric radiance, average biases become all negative with values up to -60% and -74% at 412 and 670 nm at the coast, respectively. The seasonal trend of estimated biases at the AAOT is consistent with intra-annual variation of biases from match-ups between in situ and satellite products derived with SeaDAS from SeaWiFS and MODIS data. Nevertheless, estimated biases at blue wavelengths exceed systematic differences determined from match-up analysis. This may be explained by uncertainties and approximations in the simulation procedure, and by mechanisms of compensation introduced by the turbid water correction algorithm implemented in SeaDAS.

  10. Potential interactions among disease, pesticides, water quality and adjacent land cover in amphibian habitats in the United States

    USGS Publications Warehouse

    Battaglin, William A.; Smalling, Kelly L.; Anderson, Chauncey; Calhoun, Daniel L.; Chestnut, Tara E.; Muths, Erin L.

    2016-01-01

    To investigate interactions among disease, pesticides, water quality, and adjacent land cover, we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for > 90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-km buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature.Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to

  11. Synthesis and properties of water-soluble asterisk molecules.

    PubMed

    Menger, Fredric M; Azov, Vladimir A

    2002-09-18

    An asterisk is comprised of six semirigid arms projecting from a benzene nucleus. In the case at hand, asterisks were synthesized with one, two, or three aromatic rings (connected by sulfur atoms) in each of the six arms. A phosphomonoester at the termini of each arm solubilized the asterisks in water. The colloidal properties of these amphiphilic molecules were investigated by UV-vis and fluorescence spectroscopy, calorimetry, light scattering, surface tensiometry, and pulse-gradient spin-echo NMR. Solubility, solubilization, metal binding, and micelle "seeding" experiments were also carried out. Chain-conformation and supramolecular assembly into remarkable molecular "scrolls" were investigated by X-ray analysis and electron microscopy, respectively. One of the more interesting properties of the asterisks is that they remain monomeric in water despite having as many as 19 hydrophobic aromatic rings exposed to the water. The reasons for this behavior, and the possibility of exploiting it for constructing enzyme models free from aggregation equilibria, are discussed.

  12. Paleoenvironments and hydrocarbon potential of Upper Jurassic Norphlet Formation of southwestern Alabama and adjacent coastal water area

    SciTech Connect

    Mancini, E.A.; Mink, R.M.; Bearden, B.L.

    1984-09-01

    Upper Jurassic Norphlet sediments in southwestern Alabama and the adjacent coastal water area accumulated under arid climatic conditions. The Appalachian Mountains of the eastern United States extended into southwestern Alabama, providing a barrier for air and water circulation during Norphlet deposition. Norphlet paleogeography was dominated by a broad desert plain rimmed to the north and east by the Appalachians and to the south by a developing shallow sea. Initiation of Norphlet sedimentation was a result of erosion of the southern Appalachians. Norphlet conglomerates were deposited in coalescing alluvial fans in proximity to an Appalachian source. The conglomeratic sandstones grade downdip into red-bed lithofacies that accumulated in distal portions of alluvial fan and wadi systems. Quartzose sandstones (Denkman Member) were deposited as dune and interdune sediments on a broad desert plain. The source of the sand was the updip and adjacent alluvial fan, plain, and wadi deposits. A marine transgression was initiated late in Denkman deposition, resulting in the reworking of previously deposited Norphlet sediments. Norphlet hydrocarbon potential in southwestern and offshore Alabama is excellent with four oil and gas fields already established. Petroleum traps discovered to date are primarily structural traps involving salt anticlines, faulted salt anticlines, and extensional fault traps associated with salt movement. Reservoir rocks consist of quartzose sandstones, which are principally eolian in origin. Smackover algal carbonate mudstones were probably the source for the Norphlet hydrocarbons.

  13. Potentiometric surface of Floridan Aquifer, Southwest Florida Water Management District and adjacent areas, May 1979

    USGS Publications Warehouse

    Wolansky, R.M.; Mills, L.R.; Woodham, W.M.; Laughlin, C.P.

    1979-01-01

    A May 1979 potentiometric-surface map depicts the annual low water-level period. Potentiometric levels declined 4 to 21 feet between September 1978 and May 1979, in the citrus and farming sections of southern Hillsborough, northern Hardee, southwestern Polk, northwestern DeSoto, and Manatee Counties. Water levels in these areas are widely affected by pumping for irrigation and have the greatest range in fluctuations. Water-level declines ranged from 0 to 6 feet in coastal, northern, and southern areas of the Water Management District. Generally potentiometric levels were higher than previous May levels due to heavy rains in April and May. In parts of Hillsborough, Pasco, and Pinellas Counties, May 1979 potentiometric levels were 18 feet higher than those of September 1978. (USGS)

  14. An ecological study of the KSC Turning Basin and adjacent waters

    NASA Technical Reports Server (NTRS)

    Nevin, T. A.; Lasater, J. A.; Clark, K. B.; Kalajian, E. H.

    1974-01-01

    The conditions existing in the waters and bottoms of the Turning Basin, the borrow pit near Pad 39A, and the Barge Canal connecting them were investigated to determine the ecological significance of the chemical, biological, and microbiological parameters. The water quality, biological, microbiological findings are discussed. It is recommended that future dredging activities be limited in depth, and that fill materials should not be removed down to the clay strata.

  15. Two regimes of cloud water over the Okhotsk Sea and the adjacent regions around Japan in summer

    NASA Astrophysics Data System (ADS)

    Shimada, Teruhisa; Iwasaki, Toshiki

    2015-03-01

    This study derived two regimes of cloud water with a dipole structure between over the Okhotsk Sea and over the adjacent regions around Japan in summer by using a climate index for cool summer. When the Okhotsk high develops, clouds are confined to a thin low-level layer owing to the enhanced stability in the lower atmosphere induced by the downward motion associated with the Okhotsk high. The resulting optically thin clouds allow more downward shortwave radiation to reach the surface of the Okhotsk Sea. In contrast, the low-level easterly winds blowing toward the Japanese Islands and the Eurasian continent enhance cloud formation. This is due to the convergence of the water vapor flux induced by the easterly winds associated with the Okhotsk high and the southerly winds associated with the Baiu frontal zone and the Pacific high and due to the orographic uplift of air mass. When a cyclonic circulation occurs over the Okhotsk Sea, a thick layer of low-level clouds extending close to the sea surface is formed. The convergence of the water vapor flux over the subarctic sea surface temperature (SST) frontal zone and the cool SST promote fog formation, and upward motion associated with the cyclonic circulation supports the high cloud water content from the lower to the upper troposphere. The resulting optically thick clouds reduce the downward shortwave radiation at the surface of the Okhotsk Sea. Over the regions around Japan, water vapor flux diverges owing to dry air originating from land and cloud water decreases.

  16. From single molecules to water networks: Dynamics of water adsorption on Pt(111)

    NASA Astrophysics Data System (ADS)

    Naderian, Maryam; Groß, Axel

    2016-09-01

    The adsorption dynamics of water on Pt(111) was studied using ab initio molecular dynamics simulations based on density functional theory calculations including dispersion corrections. Sticking probabilities were derived as a function of initial kinetic energy and water coverage. In addition, the energy distribution upon adsorption was monitored in order to analyze the energy dissipation process. We find that on the water pre-covered surface the sticking probability is enhanced because of the attractive water-water interaction and the additional effective energy dissipation channels to the adsorbed water molecules. The water structures forming directly after the adsorption on the pre-covered surfaces do not necessarily correspond to energy minimum structures.

  17. Trace Element Mobility in Water and Sediments in a Hyporheic Zone Adjacent to an Abandoned Uranium Mine

    NASA Astrophysics Data System (ADS)

    Roldan, C.; Blake, J.; Cerrato, J.; Ali, A.; Cabaniss, S.

    2015-12-01

    The legacy of abandoned uranium mines lead to community concerns about environmental and health effects. This study focuses on a cross section of the Rio Paguate, adjacent to the Jackpile Mine on the Laguna Reservation, west-central New Mexico. Often, the geochemical interactions that occur in the hyporheic zone adjacent to these abandoned mines play an important role in trace element mobility. In order to understand the mobility of uranium (U), arsenic (As), and vanadium (V) in the Rio Paguate; surface water, hyporheic zone water, and core sediment samples were analyzed using inductively coupled plasma mass spectroscopy (ICP-MS). All water samples were filtered through 0.45μm and 0.22μm filters and analyzed. The results show that there is no major difference in concentrations of U (378-496μg/L), As (0.872-6.78μg/L), and V (2.94-5.01μg/L) between the filter sizes or with depth (8cm and 15cm) in the hyporheic zone. The unfiltered hyporheic zone water samples were analyzed after acid digestion to assess the particulate fraction. These results show a decrease in U concentration (153-202μg/L) and an increase in As (33.2-219μg/L) and V (169-1130μg/L) concentrations compared to the filtered waters. Surface water concentrations of U(171-184μg/L) are lower than the filtered hyporheic zone waters while As(1.32-8.68μg/L) and V(1.75-2.38μg/L) are significantly lower than the hyporheic zone waters and particulates combined. Concentrations of As in the sediment core samples are higher in the first 15cm below the water-sediment interface (14.3-3.82μg/L) and decrease (0.382μg/L) with depth. Uranium concentrations are consistent (0.047-0.050μg/L) at all depths. The over all data suggest that U is mobile in the dissolved phase and both As and V are mobile in the particular phase as they travel through the system.

  18. Single ionization of water molecules in collisions with bare ions

    NASA Astrophysics Data System (ADS)

    Mondal, A.; Mandal, C. R.; Purkait, M.

    2016-04-01

    We present the double differential cross sections (DDCSs) for the direct ionization of water molecules by impact of fully stripped helium, carbon and oxygen atoms, respectively. In the present formalism, we have represented the wavefunction in the entrance channel as the product of a plane wave for the projectile and an accurate one-center-molecular wavefunction of the water molecule by Moccia (1964 J. Chem. Phys. 40 2186). In the exit channel, we have expressed the total wavefunction as the product of pair-wise Coulomb wavefunctions among the ejected electron, projectile ion and the residual target ion, respectively. The contributions of DDCSs for five different molecular orbitals of water to the spectrum of angular distributions have been analyzed for several electron emission energies. The present results for DDCSs are compared with existing experimental and theoretical findings. We find an overall good agreement between our calculated results and the experimental findings for electron emission cross sections. In addition, DDCS results for ionization from different orbitals at a few electron emission energies are given in tabular form.

  19. Effects of Withdrawals on Ground-Water Levels in Southern Maryland and the Adjacent Eastern Shore, 1980-2005

    USGS Publications Warehouse

    Soeder, Daniel J.; Raffensperger, Jeff P.; Nardi, Mark R.

    2007-01-01

    Ground water is the primary source of water supply in most areas of Maryland?s Atlantic Coastal Plain, including Southern Maryland. The counties in this area are experiencing some of the most rapid growth and development in the State, resulting in an increased demand for ground-water production. The cooperative, basic water-data program of the U.S. Geological Survey and the Maryland Geological Survey has collected long-term observations of ground-water levels in Southern Maryland and parts of the Eastern Shore for many decades. Additional water-level observations were made by both agencies beginning in the 1970s, under the Power Plant Research Program of the Maryland Department of Natural Resources. These long-term water levels commonly show significant declines over several decades, which are attributed to ground-water withdrawals. Ground-water-level trends since 1980 in major Coastal Plain aquifers such as the Piney Point-Nanjemoy, Aquia, Magothy, upper Patapsco, lower Patapsco, and Patuxent were compared to water use and withdrawal data. Potentiometric surface maps show that most of the declines in ground-water levels can be directly related to effects from major pumping centers. There is also evidence that deep drawdowns in some pumped aquifers may be causing declines in adjacent, unpumped aquifers. Water-level hydrographs of many wells in Southern Maryland show linear declines in levels year after year, instead of the gradual leveling-off that would be expected as the aquifers equilibrate with pumping. A continual increase in the volumes of water being withdrawn from the aquifers is one explanation for why they are not reaching equilibrium. Although reported ground-water production in Southern Maryland has increased somewhat over the past several decades, the reported increases are often not large enough to account for the observed water-level declines. Numerical modeling simulations indicate that a steady, annual increase in the number of small wells could

  20. Corals persisting in naturally turbid waters adjacent to a pristine catchment in Solomon Islands.

    PubMed

    Albert, Simon; Fisher, Paul L; Gibbes, Badin; Grinham, Alistair

    2015-05-15

    Few water quality measurements exist from pristine environments, with fewer reported studies of coastal water quality from Solomon Islands. Water quality benchmarks for the Solomons have relied on data from other geographic regions, often from quite different higher latitude developed nations, with large land masses. We present the first data of inshore turbidity and sedimentation rate for a pristine catchment on Isabel Island. Surveys recorded relatively high coral cover. The lowest cover was recorded at 22.7% (Jejevo) despite this site having a mean turbidity (continuous monitoring) of 32 NTU. However, a similar site (Jihro) was significantly less turbid (2.1 mean NTU) over the same period. This difference in turbidity is likely due to natural features of the Jihro River promoting sedimentation before reaching coastal sites. We provide an important baseline for Solomon Island inshore systems, whilst demonstrating the importance of continuous monitoring to capture episodic high turbidity events.

  1. Chemical and Isotopic Composition of Waters and Dissolved Gases in Some Thermal Springs of Sicily and Adjacent Volcanic Islands, Italy

    NASA Astrophysics Data System (ADS)

    Grassa, Fausto; Capasso, Giorgio; Favara, Rocco; Inguaggiato, Salvatore

    2006-04-01

    Hydrochemical (major and some minor constituents), stable isotope ([InlineMediaObject not available: see fulltext.] and [InlineMediaObject not available: see fulltext.], δ13CTDIC total dissolved inorganic carbon) and dissolved gas composition have been determined on 33 thermal discharges located throughout Sicily (Italy) and its adjacent islands. On the basis of major ion contents, four main water types have been distinguished: (1) a Na-Cl type; (2) a Ca-Mg > Na-SO4-Cl type; (3) a Ca-Mg-HCO3 type and (4) a Na-HCO3 type water. Most waters are meteoric in origin or resulting from mixing between meteoric water and heavy-isotope end members. In some samples, δ 18O values reflect the effects of equilibrium processes between thermal waters and rocks (positive 18O-shift) or thermal waters and CO2 (negative 18O-shift). Dissolved gas composition indicates the occurrence of gas/water interaction processes in thermal aquifers. N2/O2 ratios higher than air-saturated water (ASW), suggest the presence of geochemical processes responsible for dissolved oxygen consumption. High CO2 contents (more than 3000 cc/litre STP) dissolved in the thermal waters indicate the presence of an external source of carbon dioxide-rich gas. TDIC content and δ 13C TDIC show very large ranges from 4.6 to 145.3 mmol/Kg and from 10.0‰ and 2.8‰, respectively. Calculated values indicate the significant contribution from a deep source of carbon dioxide inorganic in origin. Interaction with Mediterranean magmatic CO2 characterized by heavier carbon isotope ratios ([InlineMediaObject not available: see fulltext.] value from -3 to 0‰ vs V-PDB (CAPASSO et al., 1997, GIAMMANCO et al., 1998; INGUAGGIATO et al., 2000) with respect to MORB value and/or input of CO2-derived from thermal decomposition of marine carbonates have been inferred.

  2. Continuum simulations of water flow past fullerene molecules

    NASA Astrophysics Data System (ADS)

    Popadić, A.; Praprotnik, M.; Koumoutsakos, P.; Walther, J. H.

    2015-09-01

    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 solvers, allowing for investigations into spatiotemporal scales inaccessible to atomistic simulations.

  3. Ionization of water molecules by fast charged projectiles

    SciTech Connect

    Dubois, A.; Carniato, S.; Fainstein, P. D.; Hansen, J. P.

    2011-07-15

    Single-ionization cross sections of water molecules colliding with fast protons are calculated from lowest-order perturbation theory by taking all electrons and molecular orientations consistently into account. Explicit analytical formulas based on the peaking approximation are obtained for differential ionization cross sections with the partial contribution from the various electron orbitals accounted for. The results, which are in very good agreement with total and partial cross sections at high electron and projectile energies, display a strong variation on molecular orientation and molecular orbitals.

  4. Characterizing Structural Stability of Amyloid Motif Fibrils Mediated by Water Molecules.

    PubMed

    Choi, Hyunsung; Chang, Hyun Joon; Lee, Myeongsang; Na, Sungsoo

    2017-02-04

    In biological systems, structural confinements of amyloid fibrils can be mediated by the role of water molecules. However, the underlying effect of the dynamic behavior of water molecules on structural stabilities of amyloid fibrils is still unclear. By performing molecular dynamics simulations, we investigate the dynamic features and the effect of interior water molecules on conformations and mechanical characteristics of various amyloid fibrils. We find that a specific mechanism induced by the dynamic properties of interior water molecules can affect diffusion of water molecules inside amyloid fibrils, inducing their different structural stabilities. The conformation of amyloid fibrils induced by interior water molecules show the fibrils' different mechanical features. We elucidate the role of confined and movable interior water molecules in structural stabilities of various amyloid fibrils. Our results offer insights not only in further understanding of mechanical features of amyloids as mediated by water molecules, but also in the fine-tuning of the functional abilities of amyloid fibrils for applications.

  5. Hydrogeochemistry and stable isotopes of ground and surface waters from two adjacent closed basins, Atacama Desert, northern Chile

    USGS Publications Warehouse

    Alpers, C.N.; Whittemore, D.O.

    1990-01-01

    The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two adjacent closed basins in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra Basin are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values < -3.5??? for other Hamburgo Basin waters; thus the mine waters may represent a mixture of meteoric waters with deeper "metamorphic" waters, which had interacted with rocks and exchanged oxygen isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo Basin waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra Basins have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both basins. Some of the

  6. 33 CFR 334.70 - Buzzards Bay, and adjacent waters, Mass.; danger zones for naval operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA... Ocean in vicinity of No Mans Land—(1) The area. The waters surrounding No Mans Land within an area... 41°15′30″, longitude 70°51′30″; thence northeasterly to latitude 41°17′30″, longitude...

  7. 33 CFR 334.70 - Buzzards Bay, and adjacent waters, Mass.; danger zones for naval operations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA... Ocean in vicinity of No Mans Land—(1) The area. The waters surrounding No Mans Land within an area... 41°15′30″, longitude 70°51′30″; thence northeasterly to latitude 41°17′30″, longitude...

  8. 76 FR 30023 - Pamlico Sound and Adjacent Waters, NC; Danger Zones for Marine Corps Operations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-24

    ... Subjects in 33 CFR Part 334 Danger zones, Marine safety, Navigation (water), Restricted areas, Waterways... current military training mission requires enhanced public safety and protection of vessels that operate.... Establishment of this additional danger zone will allow the Marine Corps to minimize the public safety...

  9. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Bay, Thimble Shoals Channel Anchorages. (i) Anchorage B . The waters bounded by a line connecting the... Bridge Tunnel or Monitor-Merrimac Bridge Tunnel (MMBT) must be capable of getting underway within 30 minutes with sufficient power to keep free of the bridge tunnel complex. (15) A vessel may not anchor...

  10. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Bay, Thimble Shoals Channel Anchorages. (i) Anchorage B . The waters bounded by a line connecting the... Bridge Tunnel or Monitor-Merrimac Bridge Tunnel (MMBT) must be capable of getting underway within 30 minutes with sufficient power to keep free of the bridge tunnel complex. (15) A vessel may not anchor...

  11. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Bay, Thimble Shoals Channel Anchorages. (i) Anchorage B . The waters bounded by a line connecting the... Bridge Tunnel or Monitor-Merrimac Bridge Tunnel (MMBT) must be capable of getting underway within 30 minutes with sufficient power to keep free of the bridge tunnel complex. (15) A vessel may not anchor...

  12. Interannual to Decadal Variability of Atlantic Water in the Nordic and Adjacent Seas

    NASA Technical Reports Server (NTRS)

    Carton, James A.; Chepurin, Gennady A.; Reagan, James; Haekkinen, Sirpa

    2011-01-01

    Warm salty Atlantic Water is the main source water for the Arctic Ocean and thus plays an important role in the mass and heat budget of the Arctic. This study explores interannual to decadal variability of Atlantic Water properties in the Nordic Seas area where Atlantic Water enters the Arctic, based on a reexamination of the historical hydrographic record for the years 1950-2009, obtained by combining multiple data sets. The analysis shows a succession of four multi-year warm events where temperature anomalies at 100m depth exceed 0.4oC, and three cold events. Three of the four warm events lasted 3-4 years, while the fourth began in 1999 and persists at least through 2009. This most recent warm event is anomalous in other ways as well, being the strongest, having the broadest geographic extent, being surface-intensified, and occurring under exceptional meteorological conditions. Three of the four warm events were accompanied by elevated salinities consistent with enhanced ocean transport into the Nordic Seas, with the exception of the event spanning July 1989-July 1993. Of the three cold events, two lasted for four years, while the third lasted for nearly 14 years. Two of the three cold events are associated with reduced salinities, but the cold event of the 1960s had elevated salinities. The relationship of these events to meteorological conditions is examined. The results show that local surface heat flux variations act in some cases to reinforce the anomalies, but are too weak to be the sole cause.

  13. Selenium in waters in and adjacent to the Kendrick Project, Natrona County, Wyoming

    USGS Publications Warehouse

    Crist, Marvin A.

    1975-01-01

    Selenium in concentrations exceeding the maximum limit, 0.01 milligrams per liter or 10 micrograms per liter, recommended by the U.S. Public Health Service in 'Drinking-Water Standards, 1962,' Public Health Pub. 956, is present in waters in areas near Casper, Wyo. Some streams containing selenium flow into the North Platte River upstream from several municipalities that obtain water from the river and the alluvium along the river. The area of this investigation includes about 725 square miles in Natrona County in central Wyoming. Study effort was most intensive within the area bounded by the North Platte River, Casper Creek, and Casper Canal, the approximate boundaries of the Kendrick irrigation project. Geologic formations in the area contain selenium that may have been derived from deposits of seleniferous material or from volcanic emanations brought down by rain. Formations older than Cretaceous age were not considered as important sources of selenium in waters of the area, because no irrigation water is applied to areas underlain by these rocks. The selenium concentration in 82 samples of Cretaceous rocks ranged from less than 10 to 4,200 ?g/kg (micrograms per kilogram of sample); no correlation was found between selenium concentration and the depth at which the sample was collected. Of four samples of Tertiary rocks analyzed, three contained no selenium and one had a selenium concentration of 40 ?g/kg. The selenium concentration in 93 samples of Quaternary rocks ranged from less than 10 to 52.0 ?g/kg, and the highest selenium concentration was generally found at depths less than 4 feet. No geologic formation has consistently high concentrations of selenium, but high concentrations were found at points throughout the study area. Probably the rocks in any locality could be the source of selenium in the water in the surrounding vicinity. The selenium concentration in water from some wells fluctuates widely. It is concluded that the selenium concentrations in the

  14. Surface-water features in Osceola County and adjacent areas, Florida

    USGS Publications Warehouse

    Hughes, G.H.; Frazee, James M.

    1979-01-01

    The western two-thirds of Osceola County, Fla., drains southward by way of the Kissimmee River and its tributaries; the eastern one-third drains eastward to the St. Johns River or to marshy areas that make up part of the headwaters of the St. Johns River. About 15 percent of the county is covered by several hundred lakes whose surface areas range in size from a few to several thousand acres. Much of the natural drainage has been altered by canalization or regulated by control structures. Under natural conditions streamflow is seasonal, usually high in September or October and low in May or June, in phase with the rainy season. Control structures are used to maintain lake levels within a relatively small range in stage, producing greater seasonal variations in river flow than before regulation. Dissolved-solids concentration of much of the surface water is less than 240 mg/l, in some, much less. The water typically is of calcium bicarbonate type. Color is fairly high, in water draining from swamps, where the pickup of humic acids is significant. (Kosco-USGS)

  15. Spatial and seasonal patterns of ichthyoplankton assemblages in the Haizhou Bay and its adjacent waters of China

    NASA Astrophysics Data System (ADS)

    Li, Zengguang; Ye, Zhenjiang; Wan, Rong

    2015-12-01

    Surveys were conducted in five voyages in Haizhou Bay and its adjacent coastal area from March to December 2011 during full moon spring tides. The ichthyoplankton assemblages and the environmental factors that affect their spatial and seasonal patterns were determined. Totally 35 and 12 fish egg and larvae taxa were identified, respectively. Over the past several decades, the egg and larval species composition has significantly changed in Haizhou Bay and its adjacent waters, most likely corresponding with the alteration of fishery resources, which are strongly affected by anthropogenic activities and climate change. The Bray-Curtis dissimilarity index identified four assemblages: near-shore bay assemblage, middle bay assemblage and two closely related assemblages (near-shore/middle bay assemblage and middle/edge of bay assemblage). The primary species of each assemblage principally reflected the spawning strategies of adult fish. The near-shore bay assemblage generally occurred in near-shore bay, with depths measuring <20 m, and the middle bay assemblage generally occurred in the middle of bay, with depths measuring 20 to 40 m. Spatial and seasonal variations in ichthyoplankton in each assemblage were determined by interactions between biological behavioral traits and oceanographic features, particularly the variation of local conditions within the constraint of a general reproductive strategy. The results of Spearman's rank correlation analysis indicated that both fish egg and larval abundance were positively correlated with depth, which is critical to the oceanographic features in Haizhou Bay.

  16. Zooplankton of the waters adjacent to the C. P. Crane generating station. Final report

    SciTech Connect

    Grant, G.C.; Womack, C.J.; Olney, J.E.

    1980-08-01

    Zooplankton population in the Gunpowder River and its tributaries were sampled monthly from July, 1979-March, 1980 in a continuation of similar studies begun in March, 1979. The objective of the study was to determine the effect of the present once-through cooling system of the Crane Power Plant. The principal effect of the C.P. Crane generating station on zooplankton of the area is a displacement of an original freshwater community through the pumping of cooling water from Seneca Creek to Saltpeter Creek.

  17. Assessment of the fresh-and brackish-water resources underlying Dunedin and adjacent areas on northern Pinellas County, Florida

    USGS Publications Warehouse

    Knochenmus, L.A.; Swenson, E.S.

    1996-01-01

    The city of Dunedin is enhancing their potable ground-water resources through desalination of brackish ground water. An assessment of the fresh- and brackish-water resources in the Upper Floridan aquifer was needed to estimate the changes that may result from brackish-water development. The complex hydrogeologic framework underlying Dunedin and adjacent areas of northern Pinellas County is conceptualized as a multilayered sequence of permeable zones and confining and semiconfining units. The permeable zones contain vertically spaced, discrete, water-producing zones with differing water quality. Water levels, water-level responses, and water quality are highly variable among the different permeable zones. The Upper Floridan aquifer is best characterized as a local flow system in most of northern Pinellas County. Pumping from the Dunedin well field is probably not influencing water levels in the aquifer outside Dunedin, but has resulted in localized depressions in the potentiometric surface surrounding production-well clusters. The complex geologic layering combined with the effects of production-well distribution probably contribute to the spatial and temporal variability in chloride concentrations in the Dunedin well field. Chloride concentrations in ground water underlying the Dunedin well field vary both vertically and laterally. In general, water-quality rapidly changes below depths of 400 feet below sea level. Additionally, randomly distributed water-producing zones with higher chloride concentrations may occur at shallow, discrete intervals above 400 feet. A relation between chloride concentration and distance from St. Joseph Sound is not apparent; however, a possible relation exists between chloride concentration and production-well density. Chloride-concentration data from production wells show a consistently increasing pattern that has accelerated since the late 1980's. Chloride-concentration data from 15 observation wells show increasing trends for 6 wells

  18. Larval distribution pattern of Muraenesox cinereus (Anguilliformes: Muraenesocidae) leptocephali in waters adjacent to Korea

    NASA Astrophysics Data System (ADS)

    Ji, Hwan-Sung; Kim, Jin-Koo; Oh, Taeg Yun; Choi, Kwang Ho; Choi, Jung Hwa; Seo, Young Il; Lee, Dong Woo

    2015-09-01

    To understand the transport and recruitment processes of the daggertooth pike conger, Muraenesox cinereus, in the marginal seas of East Asia, we investigated the distribution pattern, estimated spawning areas and periods, and recruitment mechanisms of M. cinereus, based on 51 individuals of leptocephali collected from Korean waters during 2010-2014. Back-calculated hatching dates, determined from the daily incremental growth rates of the otoliths, indicated that the spawning period for M. cinereus was during July-September. The size range of M. cinereus leptocephali collected offshore of Jeju Island and southeast of the Korea-Japan intermediate zone was 16.6-20.9 mm TL (age, 18-23 d). We hypothesize that one of the spawning grounds of M. cinereus is located offshore in the East China Sea. In Korean waters, the ages and body lengths of M. cinereus leptocephali increased northward from latitude 31°30'N to 34°40'N, with metamorphosis occurring at latitude 34°40'N. Therefore, we surmised that the hatched preleptocephali of M. cinereus were transported from offshore areas in the East China Sea to Jeju Island and the Korea Strait (KS) by the Kuroshio and Tsushima Warm Current.

  19. Hydrology of the coastal springs ground-water basin and adjacent parts of Pasco, Hernando, and Citrus Counties, Florida

    USGS Publications Warehouse

    Knochenmus, Lari A.; Yobbi, Dann K.

    2001-01-01

    The coastal springs in Pasco, Hernando, and Citrus Counties, Florida consist of three first-order magnitude springs and numerous smaller springs, which are points of substantial ground-water discharge from the Upper Floridan aquifer. Spring flow is proportional to the water-level altitude in the aquifer and is affected primarily by the magnitude and timing of rainfall. Ground-water levels in 206 Upper Floridan aquifer wells, and surface-water stage, flow, and specific conductance of water from springs at 10 gaging stations were measured to define the hydrologic variability (temporally and spatially) in the Coastal Springs Ground-Water Basin and adjacent parts of Pasco, Hernando, and Citrus Counties. Rainfall at 46 stations and ground-water withdrawals for three counties, were used to calculate water budgets, to evaluate long-term changes in hydrologic conditions, and to evaluate relations among the hydrologic components. Predictive equations to estimate daily spring flow were developed for eight gaging stations using regression techniques. Regression techniques included ordinary least squares and multiple linear regression techniques. The predictive equations indicate that ground-water levels in the Upper Floridan aquifer are directly related to spring flow. At tidally affected gaging stations, spring flow is inversely related to spring-pool altitude. The springs have similar seasonal flow patterns throughout the area. Water-budget analysis provided insight into the relative importance of the hydrologic components expected to influence spring flow. Four water budgets were constructed for small ground-water basins that form the Coastal Springs Ground-Water Basin. Rainfall averaged 55 inches per year and was the only source of inflow to the Basin. The pathways for outflow were evapotranspiration (34 inches per year), runoff by spring flow (8 inches per year), ground-water outflow from upward leakage (11 inches per year), and ground-water withdrawal (2 inches per year

  20. Ground-Water Hydrographs and 5-Year Ground-Water-Level Changes, 1984-93, for Selected Areas In and Adjacent to New Mexico

    USGS Publications Warehouse

    Wilkins, D.W.; Garcia, Benjamin M.

    1995-01-01

    A cooperative observation-well monitoring program was begun in New Mexico in 1925 between the U.S. Geological Survey and the New Mexico State Engineer Office. The majority of the wells are located in New Mexico; however, a few are in Texas east of Curry and Roosevelt County, New Mexico, and in Colorado along the Rio Grande. The program presently includes 22 wells equipped with continuous water-level recorders and 34 monitoring areas in which selected wells are measured periodically, usually every 5 years, to record changes in ground-water levels. These monitoring areas are those where ground water is used in large quantities for irrigation, municipal, or industrial purposes. Water-level data and water-level changes computed from these data are used to determine areas of ground-water-level rises and declines. This information is necessary for management of ground-water resources in New Mexico. Included in this report are hydrographs of ground-water levels obtained from 22 wells equipped with continuous water-level recorders and maps of ground-water-level changes computed for a 5-year period in each of 34 monitoring areas. Well locations and ground-water-level data for a 5-year period are listed in tables for each monitoring area. Where available, plots of annual precipitation data for climatological stations within or adjacent to each monitoring area are included.

  1. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36°51′45.7″ N 76°19′31.5″ W 36°51′45.8″ N 76°19′20.7″ W 36°51′37.8″ N 76°19′24.3″ W 36°51′32.5″ N 76°19′31.1″ W 36°51′40.7″ N 76°19′37.3″ W 36°51′45.7″ N 76°19′31.5″ W (ii) Anchorage N, Hospital Point. The waters bounded by a line connecting the following points: Latitude Longitude 36°51′05.4″ N...

  2. 33 CFR 110.168 - Hampton Roads, Virginia and adjacent waters (Datum: NAD 83).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36°51′45.7″ N 76°19′31.5″ W 36°51′45.8″ N 76°19′20.7″ W 36°51′37.8″ N 76°19′24.3″ W 36°51′32.5″ N 76°19′31.1″ W 36°51′40.7″ N 76°19′37.3″ W 36°51′45.7″ N 76°19′31.5″ W (ii) Anchorage N, Hospital Point. The waters bounded by a line connecting the following points: Latitude Longitude 36°51′05.4″ N...

  3. Analysis and simulation of ground-water flow in Lake Wales Ridge and adjacent areas of central Florida

    USGS Publications Warehouse

    Yobbi, Dann K.

    1996-01-01

    The Lake Wales Ridge is an uplands recharge area in central Florida that contains many sinkhole lakes. Below-normal rainfall and increased pumping of ground water have resulted in declines both in ground-water levels and in the water levels of many of the ridge lakes. A digital flow model was developed for a 3,526 square-mile area to help understand the current (1990) ground-water flow system and its response to future ground-water withdrawals. The ground-water flow system in the Lake Wales Ridge and adjacent area of central Florida consists of a sequence of sedimentary aquifers and confining units. The uppermost water-bearing unit of the study area is the surficial aquifer. This aquifer is generally unconfined and is composed primarily of clastic deposits. The surficial aquifer is underlain by the confined intermediate aquifer and confining units which consists of up to three water-bearing units composed of interbedded clastics and carbonate rocks. The lowermost unit of the ground- water flow system, the confined Upper Floridan aquifer, consists of a thick, hydraulically connected sequence of carbonate rocks. The Upper Floridan aquifer is about 1,200 to 1,400 feet thick and is the primary source for ground-water withdrawals in the study area. The generalized ground-water flow system of the Lake Wales Ridge is that water moves downward from the surficial aquifer to the intermediate aquifer and the Upper Floridan aquifer in the central area, primarily under the ridges, with minor amounts of water flow under the flatlands. The water flows laterally away fromn the central area, downgradient to discharge areas to the west, east, and south, and locally along valleys of major streams. Upward leakage occurs along valleys of major streams. The model was initially calibrated to the steady-state conditions representing September 1989. The resulting calibrated hydrologic parameters were then tested by simulating transient conditions for the period October 1989 through 1990. A

  4. Geochemistry of waters from springs, wells, and snowpack on and adjacent to Medicine Lake volcano, northern California

    USGS Publications Warehouse

    Mariner, R.H.; Lowenstern, Jacob B.

    1999-01-01

    Chemical analyses of waters from cold springs and wells of the Medicine Lake volcano and surrounding region indicate small chloride anomalies that may be due to water-rock interaction or limited mixing with high-temperature geothermal fluids. The Fall River Springs (FRS) with a combined discharge of approximately 37 m3/s, show a negative correlation between chloride (Cl) and temperature, implying that the Cl is not derived from a high-temperature geothermal fluid. The high discharge from the FRS indicates recharge over a large geographic region. Chemical and isotopic variations in the FRS show that they contain a mixture of three distinct waters. The isotopic composition of recharge on and adjacent to the volcano are estimated from the isotopic composition of snow and precipitation amounts adjusted for evapotranspiration. Enough recharge of the required isotopic composition (-100 parts per thousand ??D) is available from a combination of the Medicine Lake caldera, the Fall River basin and the Long Bell basin to support the slightly warmer components of the FRS (32 m3/s). The cold-dilute part of the FRS (approximately 5 m3/s) may recharge in the Bear Creek basin or at lower elevations in the Fall River basin.

  5. Atmospheric and Adjacency Correction of Landsat-8 Imagery of Inland and Coastal Waters Near AERONET-OC Sites

    NASA Astrophysics Data System (ADS)

    Bassani, Cristiana; Cazzaniga, Ilaria; Manzo, Ciro; Bresciani, Mariano; Braga, Federica; Giardino, Claudia; Schroeder, Thomas; Kratzer, Susanne; Brando, Vittorio

    2016-08-01

    Preliminary results of a new algorithm for the atmospheric correction of OLI imagery acquired over coastal and inland water are presented. The algorithm was based on the Second Simulation of the Satellite Signal in the Solar Spectrum (6SV) radiative transfer model and the atmopheric contribution was simulated by using the microphysical properties of the aerosol, their size distribution and refractive index, available from the AERONET stations located in the study area. The SeaDAS software was also applied to the OLI data to compare the results obtained by OLI@CRI algorithm with the standard procedure for atmospheric correction of remotely data. Furthermore, the adjacency effect was removed by the well-known empirical formula as well as a new empirical formula to assess any possible improvement of the atmospheric correction products using the diffuse fraction of the total atmospheric transmission as weight for averaged reflectance removal. To validate the results and assess its accuracy, the above-water data acquired at AERONET- OC sites were used. A coastal area and a lake are considered, where AERONET and AERONET-OC data are available. These sites cover a significant range of both atmospheric (from boreal to tropics) and water quality conditions.

  6. Comparison of fish communities in a clean-water stream and an adjacent polluted stream

    SciTech Connect

    Reash, R.J.; Berra, T.M. )

    1987-10-01

    Fish populations were studied in two parallel tributaries of the Mohican River, Ohio: Clear Fork, relatively undisturbed; and Rocky Fork, which receives industrial discharges and sewage effluent. Water quality in Rocky Fork was significantly worse than the control stream with respect to heavy metals (Cr, Cu, Fe, Ni, and Zn) and ammonia concentrations. Fish species richness and diversity increased downstream in Clear Fork but decreased downstream in Rocky Fork. Pollution-intolerant species were present in the headwaters of Rocky Fork and at all sites of Clear Fork. Fish community similarity of fish communities between corresponding headwater sites was significantly greater than similarity of corresponding downstream reaches, using polluted and unpolluted sites for comparison. Both headwater sites were dominated numerically by generalized invertebrate-feeding fish. At downstream sites in Clear Fork benthic insectivores became dominant in Rocky Fork, generalized invertebrate-feeding fish were present. Fish communities at polluted sites had comparatively lower variability of both trophic structure rank and relative abundance. The smaller populations of fish in these sites were dominated by a few pollution-tolerant species.

  7. Molecular multipole moments of water molecules in ice Ih

    NASA Astrophysics Data System (ADS)

    Batista, Enrique R.; Xantheas, Sotiris S.; Jónsson, Hannes

    1998-09-01

    We have used an induction model including dipole, dipole-quadrupole, quadrupole-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.

  8. Searching for Water and Other Molecules with JWST

    NASA Astrophysics Data System (ADS)

    Valenti, Jeff

    2015-08-01

    The James Webb Space Telescope (JWST) will be a powerful tool for measuring water and other molecules in transiting exoplanets, warm circumstellar disks, brown dwarfs, and cool stars. In early 2019 the observatory is scheduled to begin science operations near the Sun-Earth L2 Lagrange point. The sunshield will allow the telescope and science instrument module to cool passively to approximately 40 K. The segmented primary mirror has 25 square meters of collecting area, giving the observatory unprecedented sensitivity in the infrared. JWST has four science instruments that cover wavelengths from 0.6 to 28 microns at spectral resolutions up to about R=3000. I will summarize relevant observatory constraints, instrument capabilities, and observing templates. I will illustrate practical issues with examples from the Science Operations Design Reference Mission. Finally, I will discuss the Cycle 1 proposal process, which begins in 2017.

  9. Evaluation of ground-water contribution to streamflow in coastal Georgia and adjacent parts of Florida and South Carolina

    USGS Publications Warehouse

    Priest, Sherlyn

    2004-01-01

    Stream-aquifer relations in the coastal area of Georgia and adjacent parts of Florida and South Carolina were evaluated as part of the Coastal Georgia Sound Science Initiative, the Georgia Environmental Protection Division's strategy to protect the Upper Floridan aquifer from saltwater intrusion. Ground-water discharge to streams was estimated using three methods: hydrograph separation, drought-streamflow measurements, and linear-regression analysis of streamflow duration. Ground-water discharge during the drought years of 1954, 1981, and 2000 was analyzed for minimum ground-water contribution to streamflow. Hydrograph separation was used to estimate baseflow at eight streamflow gaging stations during the 31-year period 1971?2001. Six additional streamflow gaging stations were evaluated using linear-regression analysis of flow duration to determine mean annual baseflow. The study area centers on three major river systems ? the Salkehatchie?Savannah?Ogeechee, Altamaha?Satilla?St Marys, and Suwannee ? that interact with the underlying ground-water system to varying degrees, largely based on the degree of incision of the river into the aquifer and on the topography. Results presented in this report are being used to calibrate a regional ground-water flow model to evaluate ground-water flow and stream-aquifer relations of the Upper Floridan aquifer. Hydrograph separation indicated decreased baseflow to streams during drought periods as water levels declined in the aquifer. Average mean annual baseflow ranged from 39 to 74 percent of mean annual streamflow, with a mean contribution of 58 percent for the period 1971?2001. In a wet year (1997), baseflow composed from 33 to 70 percent of mean annual streamflow. Drought-streamflow analysis estimated baseflow contribution to streamflow ranged from 0 to 24 percent of mean annual streamflow. Linear-regression analysis of streamflow duration estimated the Q35 (flow that is equaled or exceeded 35 percent of the time) as the most

  10. Photosynthesis irradiance parameters and community structure associated with coastal filaments and adjacent waters in the northern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Toon, Rory K.; Lohrenz, Steven E.; Rathbun, Catherine E.; Michelle Wood, A.; Arnone, Robert A.; Jones, Burton H.; Kindle, John C.; Weidemann, Alan D.

    Comparisons were made among size-fractionated photosynthesis-irradiance ( P- E) parameters, chlorophyll a size distributions, and accessory pigment composition of natural phytoplankton assemblages in filaments, coastal upwelling waters, and an oligotrophic region of the northern Arabian Sea during the Fall Intermonsoon in 1995. Differences between P- E parameters, PBmax and αB, were observed between filaments and adjacent waters and were associated with differences in phytoplankton community structure. In a southern filament and coastal upwelled waters, the majority of the estimated biomass (chlorophyll a) was present in the larger (2-20 and 20-200 μm) size fractions; dominant accessory pigments were 19'-butanoyloxyfucoxanthin and peridinin. In higher salinity waters, high percentages of chlorophyll a and lutein/zeaxanthin were observed in the smallest size-fraction (<2 μm). Whole water values of PBmax ranged from 1.77 to 2.31 (g C g chl a-1 h -1) when the majority of the biomass was in the largest fractions. Higher values (more than 4.48 g C g chl a-1 h -1) were determined in whole water samples for communities comprised primarily of small cells. A size dependence was also observed in the value of αB, 0.017 or greater (g C g chl a-1 h -1)/(μmol quanta m -2 s -1) for whole water samples at stations dominated by small cells and 0.013 when derived from stations dominated by large cells. The observed pattern of larger phytoplankton associated with upwelling and filament waters was consistent with previous investigations and was, for the most part, comparable to findings in the California Current system. Our results show that differences in taxonomic composition and photosynthetic characteristics were indeed present between filament waters and other distinct regions; these results suggest that taxonomic variations may be associated with size-related variations in P- E parameters. Our findings provide a unique data set describing filament biology in the northern

  11. Geomorphic data collected within and adjacent to Nebraska Public Power District's Cottonwood Ranch Property, Platte River, Nebraska, Water Year 2002

    USGS Publications Warehouse

    Kinzel, Paul; Parker, Randolph; Nelson, Jonathan; Gyetvai, Steven; Burman, Aaron; Heckman, Ashley

    2003-01-01

    River-channel topographic surveys were conducted and bed-material samples were collected along transects across the Platte River during water year 2002 (October 1, 2001 to September 30, 2002). A total of 57 transect lines or cross sections were established within three study reaches located along the middle channel of the Platte River in a 2,650-acre parcel of land owned by the Nebraska Public Power District (NPPD), hereinafter referred to as the Cottonwood Ranch Property. Five additional cross sections were established downstream of the Cottonwood Ranch Property across the entire width of the Platte River as a component of a proposed future general monitoring program. A development and enhancement plan is proposed by NPPD on the Cottonwood Ranch Property to satisfy their Federal Energy Regulatory Commission (FERC) relicensing guidelines. The goal of the plan is to improve habitat along this reach for endangered species. The United States Geological Survey (USGS) designed a monitoring and research program to study and detect what effects, if any, these channel management actions have on channel morphology and sediment transport within and adjacent to the Cottonwood Ranch Property. This report presents the data-collection methods and summarizes the geomorphic data collected in support of the monitoring program for water year 2002.

  12. Temporal and spatial distribution of red tide outbreaks in the Yangtze River Estuary and adjacent waters, China.

    PubMed

    Liu, Lusan; Zhou, Juan; Zheng, Binghui; Cai, Wenqian; Lin, Kuixuan; Tang, Jingliang

    2013-07-15

    Between 1972 and 2009, evidence of red tide outbreaks in the Yangtze River Estuary and adjacent waters was collected. A geographic information system (GIS) was used to analyze the temporal and spatial distribution of these red tides, and it was subsequently used to map the distribution of these events. The results show that the following findings. (1) There were three red tide-prone areas: outside the Yangtze River Estuary and the eastern coast of Sheshan, the Huaniaoshan-Shengshan-Gouqi waters, and the Zhoushan areas and eastern coast of Zhujiajian. In these areas, red tides occurred 174 total times, 25 of which were larger than 1000 km(2) in areal extent. After 2000, the frequency of red tide outbreaks increased significantly. (2) During the months of May and June, the red tide occurrence in these areas was 51% and 20%, respectively. (3) Outbreaks of the dominant red tide plankton species Prorocentrum dong-haiense, Skeletonema costatum, Prorocentrum dantatum, and Noctiluca scientillan occurred 38, 35, 15, and 10 times, respectively, during the study interval.

  13. Characterization of surface-water resources in the Great Basin National Park area and their susceptibility to ground-water withdrawals in adjacent valleys, White Pine County, Nevada

    USGS Publications Warehouse

    Elliott, Peggy E.; Beck, David A.; Prudic, David E.

    2006-01-01

    Eight drainage basins and one spring within the Great Basin National Park area were monitored continually from October 2002 to September 2004 to quantify stream discharge and assess the natural variability in flow. Mean annual discharge for the stream drainages ranged from 0 cubic feet per second at Decathon Canyon to 9.08 cubic feet per second at Baker Creek. Seasonal variability in streamflow generally was uniform throughout the network. Minimum and maximum mean monthly discharges occurred in February and June, respectively, at all but one of the perennial streamflow sites. Synoptic-discharge, specific-conductance, and water- and air-temperature measurements were collected during the spring, summer, and autumn of 2003 along selected reaches of Strawberry, Shingle, Lehman, Baker, and Snake Creeks, and Big Wash to determine areas where surface-water resources would be susceptible to ground-water withdrawals in adjacent valleys. Comparison of streamflow and water-property data to the geology along each stream indicated areas where surface-water resources likely or potentially would be susceptible to ground-water withdrawals. These areas consist of reaches where streams (1) are in contact with permeable rocks or sediments, or (2) receive water from either spring discharge or ground-water inflow.

  14. Water depth-composition trends in ferromanganese crusts adjacent to the California margin compared to those in equatorial Pacific crusts

    NASA Astrophysics Data System (ADS)

    Conrad, T. A.; Hein, J. R.

    2013-12-01

    Ferromanganese (Fe-Mn) crusts have been used as proxies for paleo-seawater chemistry; however, element concentrations and growth rates in crusts can vary depending on the region, latitude, and water depth. Here we will look at 130 Fe-Mn crusts from seven seamounts adjacent to the California (CA) margin to explore trends in composition with water depth and latitude. Crusts were collected by ROV, resulting in a dataset with exact water depth and location coordinates. Water depth ranges from 570 to 3,934 m along a 700-km transect running roughly parallel to the CA margin. Crust samples used for comparison were collected by dredging along transects following the Gilbert Ridge and Tokelau Seamounts in the western equatorial Pacific, with water depths ranging from about 1,500 to 4,800 m. In addition to variations with latitude and water depth, element concentrations in CA margin crusts are influenced by high primary productivity in surface waters, terrestrial input, and upwelling along the continental margin. Elements associated with terrestrial input, including Na, Si, Al, K, Pb, and particularly Th, are enriched in CA margin crusts relative to crusts from the equatorial Pacific transects. Si is also associated with the biogenic phase, as are P, Ba, and Cu but these elements are lower in CA margin crusts. Ba is a proxy for primary productivity. CA margin crusts show Ba increasing with increasing water depth, while equatorial Pacific crusts show the inverse trend. In equatorial Pacific crusts, Ba correlates with decreasing latitude, which reflects increasing proximity to the high productivity zone of equatorial upwelling; additionally, local obstructional upwelling associated with primary productivity around seamounts and islands enhances the productivity signal. Cu, which is associated with the manganese oxide phase, in addition to the biogenic phase, also increases with water depth along the CA margin; this is consistent with the seawater profile for dissolved Cu. In

  15. Geochemistry of ground water in alluvial basins of Arizona and adjacent parts of Nevada, New Mexico, and California

    USGS Publications Warehouse

    Robertson, Frederick N.

    1991-01-01

    Chemical and isotope analyses of ground water from 28 basins in the Basin and Range physiographic province of Arizona and parts of adjacent States were used to evaluate ground-water quality, determine processes that control ground-water chemistry, provide independent insight into the hydrologic flow system, and develop information transfer. The area is characterized by north- to northwest-trending mountains separated by alluvial basins that form a regional topography of alternating mountains and valleys. On the basis of ground-water divides or zones of minimal basin interconnection, the area was divided into 72 basins, each representing an individual aquifer system. These systems are joined in a dendritic pattern and collectively constitute the major water resource in the region. Geochemical models were developed to identify reactions and mass transfer responsible for the chemical evolution of the ground water. On the basis of mineralogy and chemistry of the two major rock associations of the area, a felsic model and a mafic model were developed to illustrate geologic, climatic, and physiographic effects on ground-water chemistry. Two distinct hydrochemical processes were identified: (1) reactions of meteoric water with minerals and gases in recharge areas and (2) reactions of ground water as it moves down the hydraulic gradient. Reactions occurring in recharge and downgradient areas can be described by a 13-component system. Major reactions are the dissolution and precipitation of calcite and dolomite, the weathering of feldspars and ferromagnesian minerals, the formation of montmorillonite, iron oxyhydroxides, and probably silica, and, in some basins, ion exchange. The geochemical modeling demonstrated that relatively few phases are required to derive the ground-water chemistry; 14 phases-12 mineral and 2 gas-consistently account for the chemical evolution in each basin. The final phases were selected through analysis of X-ray diffraction and fluorescence data

  16. Shallow ground-water quality adjacent to burley tobacco fields in northeastern Tennessee and southwestern Virginia, spring 1997

    USGS Publications Warehouse

    Johnson, G.C.; Connell, J.F.

    2001-01-01

    In 1994, the U.S. Geological Survey began an assessment of the upper Tennessee River Basin as part of the National Water-Quality Assessment (NAWQA) Program. A ground-water land-use study conducted in 1996 focused on areas with burley tobacco production in northeastern Tennessee and southwestern Virginia. Land-use studies are designed to focus on specific land uses and to examine natural and human factors that affect the quality of shallow ground water underlying specific types of land use. Thirty wells were drilled in shallow regolith adjacent to and downgradient of tobacco fields in the Valley and Ridge Physiographic Province of the upper Tennessee River Basin. Ground-water samples were collected between June 4 and July 9, 1997, to coincide with the application of the majority of pesticides and fertilizers used in tobacco production. Ground-water samples were analyzed for nutrients, major ions, 79 pesticides, 7 pesticide degradation products, 86 volatile organic compounds, and dissolved organic carbon. Nutrient concentrations were lower than the levels found in similar NAWQA studies across the United States during 1993-95. Five of 30 upper Tennessee River Basin wells (16.7 percent) had nitrate levels exceeding 10 mg/L while 19 percent of agricultural land-use wells nationally and 7.9 percent in the Southeast had nitrate concentrations exceeding 10 mg/L. Median nutrient concentrations were equal to or less than national median concentrations. All pesticide concentrations in the basin were less than established drinking water standards, and pesticides were detected less frequently than average for other NAWQA study units. Atrazine was detected at 8 of 30 (27 percent) of the wells, and deethylatrazine (an atrazine degradation product) was found in 9 (30 percent) of the wells. Metalaxyl was found in 17 percent of the wells, and prometon, flumetralin, dimethomorph, 2,4,5-T, 2,4-D, dichlorprop, and silvex were detected once each (3 percent). Volatile organic compounds

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

    SciTech Connect

    Chempath, Shaji; Pratt, Lawrence R

    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.

  18. Engineering and Environmental Study of DDT Contamination of Huntsville Spring Branch, Indian Creek and Adjacent Lands and Waters, Wheeler Reservoir, Alabama. Revision,

    DTIC Science & Technology

    1984-04-01

    AD-A142 517 ENGINEERING AND ENVIRONMENTAL STUDY OF DDT CONTAMINATION OF HUNTSVILLE SP..(U) WATER AND AIR RESEARCH INC GAINESVILLE FL d H...DDT Con- tamination of Huntsville Spring Branch, Indian Creek and Adjacent Lands and Waters , Wheeler Reservoir, Alabama a. i irk ut iPOR...Pruitt and J. C. Nichols 8. CONTRACT OR GRANT NUMBER)» DACW01-79-C-0224 9. PERFORMING ORGANIZATION NAME AND ADDRESS Water and Air Research

  19. Quantum Tunneling of Water in Beryl: A New State of the Water Molecule.

    PubMed

    Kolesnikov, Alexander I; Reiter, George F; Choudhury, Narayani; Prisk, Timothy R; Mamontov, Eugene; Podlesnyak, Andrey; Ehlers, George; Seel, Andrew G; Wesolowski, David J; Anovitz, Lawrence M

    2016-04-22

    Using neutron scattering and ab initio simulations, we document the discovery of a new "quantum tunneling state" of the water molecule confined in 5 Å channels in the mineral beryl, characterized by extended proton and electron delocalization. We observed a number of peaks in the inelastic neutron scattering spectra that were uniquely assigned to water quantum tunneling. In addition, the water proton momentum distribution was measured with deep inelastic neutron scattering, which directly revealed coherent delocalization of the protons in the ground state.

  20. Quantum Tunneling of Water in Beryl. A New State of the Water Molecule

    DOE PAGES

    Kolesnikov, Alexander I.; Reiter, George F.; Choudhury, Narayani; ...

    2016-04-22

    When using neutron scattering and ab initio simulations, we document the discovery of a new “quantum tunneling state” of the water molecule confined in 5 Å channels in the mineral beryl, characterized by extended proton and electron delocalization. We observed a number of peaks in the inelastic neutron scattering spectra that were uniquely assigned to water quantum tunneling. Additionally, the water proton momentum distribution was measured with deep inelastic neutron scattering, which directly revealed coherent delocalization of the protons in the ground state.

  1. Simulation of Integrated Surface-Water/Ground-Water Flow and Salinity for a Coastal Wetland and Adjacent Estuary

    DTIC Science & Technology

    2004-01-01

    of MODFLOW (McDonald and Har- baugh, 1988) and MT3DMS (Zheng and Wang, 1999), was designed to solve the three-dimensional variable-density ground...hydraulically resistive layer at the land surface, which for the Everglades application, corresponds to the peat and marl unit overlying the Biscayne aquifer...0 is the density of the surface water [ML -3]. This approximation for the flux through the unsaturated zone is based on the approach used by MODFLOW

  2. Water temperature, streamflow, and ground-water elevation in and adjacent to the Russian river between Hopland and Guerneville, California from 1998-2002

    USGS Publications Warehouse

    Cox, Marisa H.; Hatch, Christine

    2003-01-01

    Temperature, water level elevation, stage height, and river discharge data for this report were collected in and adjacent to the Russian River from Hopland to Guerneville, CA over a four-year period from 1998 to 2002 to establish baselines for long-term water quality, water supply and habitat. Data files presented in this report were collected by the USGS and the Sonoma County Water Agency's Engineering Resource and Planning, and Natural Resource Divisions. Temperature data were collected in single-channel submersible microloggers or temperature data were collected simultaneously with water-elevation data in dual-channel down-hole data loggers. Stream stage and streamflow data were collected at USGS stream gaging stations located near Hopland, Healdsburg, and Guerneville over a 130 km reach of the Russian River. During the period of record stream flow ranged from 3 to 1458 m3/s. Stream temperature ranged from 8 to 29 oC while groundwater temperature ranged from 10 to 38 oC. Stream stage varied 5 m seasonly, while ground-water level varied 19 m over the same time scale.

  3. Taxonomic review of Hadromerida (Porifera, Demospongiae) from British Columbia, Canada, and adjacent waters, with the description of nine new species.

    PubMed

    Austin, William C; Ott, Bruce S; Reiswig, Henry M; Romagosa, Paula; Mcdaniel, Neil G

    2014-06-26

    The history of sponge collecting and systematics in British Columbia is reviewed over the period 1878 to 1966. Recent additions and changes are provided in an on-line species list: www.mareco/org/kml/projects/NEsponges.asp. Hadromerids are the focus of this paper as eight of 19 species in British Columbia are considered new. An additional new species is described from southern California to clarify the status of Tethya californiana in BC. An update is timely for hadromerids in BC as there is new material and renewed interest, while existing descriptions are often inadequate. We describe new species and provide additions to previous descriptions for sponges of the order Hadromerida (Porifera: Demospongiae) in the cold temperate NE Pacific off British Columbia and adjacent waters. We propose one range extension and one new species in Clionaidae; two range extensions and five new species in Polymastiidae; one range extension, two name changes and two new species in Suberitidae; and one new species in Tethyidae. New species include Pione gibraltarensis n.sp., Polymastia piscesae n. sp., Radiella endeavourensis n. sp., Sphaerotylus raphidophora n. sp., Sphaerotylus verenae n. sp., Weberella perlucida n. sp., Prosuberites saanichensis n. sp., Suberites lambei n. sp., and Tethya vacua n. sp..

  4. The influence of mariculture on mercury distribution in sediments and fish around Hong Kong and adjacent mainland China waters.

    PubMed

    Liang, Peng; Shao, Ding-Ding; Wu, Sheng-Chun; Shi, Jian-Bo; Sun, Xiao-lin; Wu, Fu-Yong; Lo, S C L; Wang, Wen-Xiong; Wong, Ming H

    2011-02-01

    To study the influence of mariculture on mercury (Hg) speciation and distribution in sediments and cultured fish around Hong Kong and adjacent mainland China waters, sediment samples were collected from six mariculture sites and the corresponding reference sites, 200-300 m away from the mariculture sites. Mariculture activities increased total mercury, organic matter, carbon, nitrogen and sulfur concentrations in the surface sediments underneath mariculture sites, possibly due to the accumulation of unconsumed fish feed and fish excretion. However, methylmercury (MeHg) concentrations and the ratio of MeHg to THg (% MeHg) in sediments underneath mariculture sites were lower than the corresponding reference sites. The % MeHg in sediments was negatively correlated (r = -0.579, p < 0.05) with organic matter (OM) content among all sites, indicating that OM may have inhibited Hg methylation in surface sediments. Three mariculture fish species were collected from each mariculture site, including red snapper (Lutjanus campechanus), orange-spotted grouper (Epinephelus coioides) and snubnose pompano (Trachinotus blochii). The average MeHg concentration in fish muscle was 75 μg kg⁻¹ (wet weight), and the dietary intake of MeHg through fish consumption for Hong Kong residents was 0.37 μg kg⁻¹ week⁻¹, which was lower than the corresponding WHO limits (500 μg kg⁻¹ and 1.6 μg kg⁻¹ week⁻¹).

  5. Relationships of surface water, pore water, and sediment chemistry in wetlands adjacent to Great Salt Lake, Utah, and potential impacts on plant community health.

    PubMed

    Carling, Gregory T; Richards, David C; Hoven, Heidi; Miller, Theron; Fernandez, Diego P; Rudd, Abigail; Pazmino, Eddy; Johnson, William P

    2013-01-15

    We collected surface water, pore water, and sediment samples at five impounded wetlands adjacent to Great Salt Lake, Utah, during 2010 and 2011 in order to characterize pond chemistry and to compare chemistry with plant community health metrics. We also collected pore water and sediment samples along multiple transects at two sheet flow wetlands during 2011 to investigate a potential link between wetland chemistry and encroachment of invasive emergent plant species. Samples were analyzed for a suite of trace and major elements, nutrients, and relevant field parameters. The extensive sampling campaign provides a broad assessment of Great Salt Lake wetlands, including a range of conditions from reference to highly degraded. We used nonmetric multidimensional scaling (NMS) to characterize the wetland sites based on the multiple parameters measured in surface water, pore water, and sediment. NMS results showed that the impounded wetlands fall along a gradient of high salinity/low trace element concentrations to low salinity/high trace element concentrations, whereas the sheet flow wetlands have both elevated salinity and high trace element concentrations, reflecting either different sources of element loading or different biogeochemical/hydrological processes operating within the wetlands. Other geochemical distinctions were found among the wetlands, including Fe-reducing conditions at two sites and sulfate-reducing conditions at the remaining sites. Plant community health metrics in the impounded wetlands showed negative correlations with specific metal concentrations in sediment (THg, Cu, Zn, Cd, Sb, Pb, Ag, Tl), and negative correlations with nutrient concentrations in surface water (nitrite, phosphate, nitrate). In the sheet flow wetlands, invasive plant species were inversely correlated with pore water salinity. These results indicate that sediment and pore water chemistry play an important role in wetland plant community health, and that monitoring and

  6. Electron capture by bare ions on water molecules

    NASA Astrophysics Data System (ADS)

    Rivarola, Roberto; Montenegro, Pablo; Monti, Juan; Fojón, Omar

    2016-05-01

    Single electron capture from water molecules by impact of bare ions is theoretically investigated at intermediate and high collision energies. This reaction is of fundamental importance to determine the deposition of energy in biological matter irradiated with ion beams (hadrontherapy), dominating other ionizing processes of the target at low-intermediate impact velocities and giving principal contributions to the energetic region where electronic stopping power maximizes. The dynamics of the interaction between the aggregates is described within the one active-electron continuum distorted wave-eikonal initial state theory. The orbitals of the target in the ground state are represented using the approximate self-consistent complete neglect of differential orbitals (SC-CNDO) model. The contribution of different molecular orbitals on the partial cross sections to selected n-principal quantum number projectile states is discriminated as well as the collaboration of these n-states on total cross sections. The latter ones are dominated by capture to n=1 states at high enough energies decreasing their contribution as n increases.

  7. [Effects of macro-jellyfish abundance dynamics on fishery resource structure in the Yangtze River estuary and its adjacent waters].

    PubMed

    Shan, Xiu-Juan; Zhuang, Zhi-Meng; Jin, Xian-Shi; Dai, Fang-Qun

    2011-12-01

    Based on the bottom trawl survey data in May 2007 and May and June 2008, this paper analyzed the effects of the abundance dynamics of macro-jellyfish on the species composition, distribution, and abundance of fishery resource in the Yangtze River estuary and its adjacent waters. From May 2007 to June 2008, the average catch per haul and the top catch per haul of macro-jellyfish increased, up to 222.2 kg x h(-1) and 1800 kg x h(-1) in June 2008, respectively. The macro-jellyfish were mainly distributed in the areas around 50 m isobath, and not beyond 100 m isobath where was the joint front of the coastal waters of East China Sea, Yangtze River runoff, and Taiwan Warm Current. The main distribution area of macro-jellyfish in June migrated northward, as compared with that in May, and the highest catches of macro-jellyfish in May 2007 and May 2008 were found in the same sampling station (122.5 degrees E, 28.5 degrees N). In the sampling stations with higher abundance of macro-jellyfish, the fishery abundance was low, and the fishery species also changed greatly, mainly composed by small-sized species (Trachurus japonicus, Harpadon nehereus, and Acropoma japonicum) and pelagic species (Psenopsis anomala, Octopus variabilis) and Trichiurus japonicus, and P. anomala accounted for 23.7% of the total catch in June 2008. Larimichthys polyactis also occupied higher proportion of the total catch in sampling stations with higher macro-jellyfish abundance, but the demersal species Lophius litulon was not found, and a few crustaceans were collected. This study showed that macro-jellyfish had definite negative effects on the fishery community structure and abundance in the Yangtze River estuary fishery ecosystem, and further, changed the energy flow patterns of the ecosystem through cascading trophic interactions. Therefore, macro-jellyfish was strongly suggested to be an independent ecological group when the corresponding fishery management measures were considered.

  8. Integration of multi-source data for water quality classification in the Pearl River estuary and its adjacent coastal waters of Hong Kong

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoling; Li, Yok Shueng; Liu, Zhigang; Yin, Kedong; Li, Zhilin; Wai, Onyx WH.; King, Bruce

    2004-10-01

    The spatial patterns of water quality were studied by integrating a Landsat TM image, 58 in situ water quality datasets and 30 samples from two concentration maps of water quality parameters derived from SeaWiFS and NOAA/AVHRR images in the Pearl River estuary and the adjacent coastal waters of Hong Kong. The reflectance of TM bands 1-4 was derived by using the COST method. The normalized difference water index (NDWI) was extracted from the raw image and the threshold segmentation was used to retrieve the water pixels of spectral reflectance. In order to study the spectral reflectance categories related to water quality, a dataset comprising 88 sampling points from four spectral bands of a Landsat TM image was used. The samples were positioned according to the availability of water quality parameters in the study area, and five reflectance classes could be finally distinguished by using the cluster analysis. Three supervised classifiers, maximum likelihood (MLH), neural network (NN) and support vector machine (SVM), were employed to recognize the spatial patterns of ocean color. All the 88 samples were divided into two data sets: 65 in the training data set and 23 in the testing data set. The classification results using the three methods showed similar spatial patterns of spectral reflectance, although the classification accuracies were different. In order to verify our assumption that the spatial patterns of water quality in the coastal waters could be indirectly detected by ocean color classification using the Landsat TM image, five optically active water quality parameters: turbidity (TURB), suspended sediments (SS), total volatile solid (TVS), chlorophyll-a (Chl-a) and phaeo-pigment (PHAE), were selected to implement the analysis of variance (ANOVA). The analysis showed that a statistically significant difference in water quality clearly existed among the five classes of spectral reflectance. It was concluded that the five classes classified by reflectance

  9. Assessment of water resources in lead-zinc mined areas in Cherokee County, Kansas, and adjacent areas

    USGS Publications Warehouse

    Spruill, Timothy B.

    1987-01-01

    A study was conducted to evaluate water-resources problems related to abandoned lead and zinc mines in Cherokee County, Kansas, and adjacent areas in Missouri and Oklahoma. Past mining activities have caused changes in the hydrogeology of the area. Lead and zinc mining has caused discontinuities and perforations in the confining shale west of the Pennsylvanian-Mississippian geologic contact (referred to as the western area), which have created artificial ground-water recharge and discharge areas. Recharge to the shallow aquifer (rocks of Mississippian age) through collapses, shafts, and drill holes in the shale has caused the formation of a ground-water 'mound' in the vicinity of the Picher Field in Kansas and Oklahoma. Discharge of mine-contaminated ground water to Tar Creek occurs in Oklahoma from drill holes and shafts where the potentiometric surface of the shallow aquifer is above the land surface. Mining of ore in the shallow aquifer has resulted in extensive fracturing and removal of material, which has created highly transmissive zones and voids and increased ground-water storage properties of the aquifer. In the area east of the Pennsylvanian-Mississippian geologic contact (referred to as the eastern area), fractured rock and tailings on the land surface increased the amount of water available for infiltration to the shallow aquifer; in the western area, tailings on the impermeable shale created artificial, perched aquifer systems that slowly drain to surface streams. Pumping of the deep aquifer (rocks of Cambrian and Ordovician age) by towns and industries, which developed as a result of the mining industry, has resulted in a potential for downward movement of water from the shallow aquifer. The potential is greatest in Ottawa County, Oklahoma. Because of the large volume of water that may be transported from the shallow to the deep aquifer, open drill holes or casings present the greatest contamination hazard to water supplies in the deep aquifer. Mining

  10. O^- channels of Dissociative Electron Attachment to water and heavy water molecules

    NASA Astrophysics Data System (ADS)

    Adaniya, Hidehito; Rudek, Benedikt; Osipov, Timur; Lee, Sun; Weber, Thorsten; Hertlein, Marcus; Schoeffler, Markus; Prior, Mike; Belkacem, Ali

    2009-05-01

    A COLTRIM technique is modified to measure the kinetic energy and angular distribution of O^- ions arising from dissociative electron attachment to water and heavy water molecules. A low energy pulsed electron, an effusive water target, a pulsed extraction plate are used in combination with the COLTRIMS spectrometer. The spectrometer carries an electrostatic lens system to compensate the effusiveness of the target. This technique is applied to study the O^- channels in the three Feshbach resonances of water and heavy water anion. The measured kinetic energy release will give the energy partitioning among the fragments, and the means to identify the two-body and three-body breakup channels. The angular distribution of the O^- ions with respect to the electron beam is found to reflect well the breakup dynamics of the H2O^- at the dissociation. The experimental results are compared with the theoretical predictions.

  11. Seasonal dynamics of particulate organic matter in the Changjiang Estuary and adjacent coastal waters illustrated by amino acid enantiomers

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Liu, Zongguang; Hu, Jun; Zhu, Zhuoyi; Liu, Sumei; Zhang, Jing

    2016-02-01

    Total suspended matter (TSM) was collected in the Changjiang Estuary and adjacent areas of the East China Sea in July, August, and November 2011, to study the composition and fate of particulate organic nitrogen (PON) during an August typhoon event and bottom trawling activities. Concentrations of particulate organic carbon (POC), particulate nitrogen (PN), and hydrolyzable particulate amino acids (PAA, D- and L-enantiomers) were higher during July and August than during November; however, D-arginine and alanine levels were significantly higher in November. Seasonal trends in the composition of PAAs indicate that in situ production is a key factor in their temporal distribution. No significant increase in TSM or decrease in labile organic matter was observed during the transit period following a typhoon event in August. In contrast, higher primary production was observed at this time as a result of the penetration of Changjiang Diluted Water caused by the typhoon event. Trawling effects were studied by comparing the calm season (July) with the bottom-trawling period (November) at similar sampling sites. The effect of trawling on the composition of bottom organic matter was studied by comparing D-amino acids concentrations and C/N ratios in the calm season (July) with the bottom-trawling period (November). A substantial contribution of microbial organic matter during the November cruise was indicated by a decrease in glutamic acid, an increase in TSM and D-alanine, and a lower carbon/nitrogen (C/N) ratio. In shallow coastal regions, anthropogenic activities (bottom trawling) may enhance the transfer of low-nutritional-value particulate organic matter into the benthic food chain.

  12. The impact of pumped water from a de-watered Magnesian limestone quarry on an adjacent wetland: Thrislington, County Durham, UK.

    PubMed

    Mayes, W M; Large, A R G; Younger, P L

    2005-12-01

    Although quarrying is often cited as a potential threat to wetland systems, there is a lack of relevant, quantitative case studies in the literature. The impact of pumped groundwater discharged from a quarry into a wetland area was assessed relative to reference conditions in an adjacent fen wetland that receives only natural runoff. Analysis of vegetation patterns at the quarry wetland site, using Detrended Correspondence Analysis and the species indicator values of Ellenberg, revealed a clear disparity between community transitions in the quarry wetland and the reference site. Limited establishment of moisture-sensitive taxa, the preferential proliferation of robust wetland species and an overall shift towards lower species diversity in the quarry wetland were explicable primarily by the physico-chemical environment created by quarry dewatering. This encompassed high pH (up to 12.8), sediment-rich effluent creating a nutrient-poor substrate with poor moisture retention in the quarry wetland, and large fluctuations in water levels.

  13. A strategy for the incorporation of water molecules present in a ligand binding site into a three-dimensional quantitative structure--activity relationship analysis.

    PubMed

    Pastor, M; Cruciani, G; Watson, K A

    1997-12-05

    Water present in a ligand binding site of a protein has been recognized to play a major role in ligand-protein interactions. To date, rational drug design techniques do not usually incorporate the effect of these water molecules into the design strategy. This work represents a new strategy for including water molecules into a three-dimensional quantitative structure-activity relationship analysis using a set of glucose analogue inhibitors of glycogen phosphorylase (GP). In this series, the structures of the ligand-enzyme complexes have been solved by X-ray crystallography, and the positions of the ligands and the water molecules at the ligand binding site are known. For the structure-activity analysis, some water molecules adjacent to the ligands were included into an assembly which encompasses both the inhibitor and the water involved in the ligand-enzyme interaction. The mobility of some water molecules at the ligand binding site of GP gives rise to differences in the ligand-water assembly which have been accounted for using a simulation study involving force-field energy calculations. The assembly of ligand plus water was used in a GRID/GOLPE analysis, and the models obtained compare favorably with equivalent models when water was excluded. Both models were analyzed in detail and compared with the crystallographic structures of the ligand-enzyme complexes in order to evaluate their ability to reproduce the experimental observations. The results demonstrate that incorporation of water molecules into the analysis improves the predictive ability of the models and makes them easier to interpret. The information obtained from interpretation of the models is in good agreement with the conclusions derived from the structural analysis of the complexes and offers valuable insights into new characteristics of the ligands which may be exploited for the design of more potent inhibitors.

  14. A nano-sized container for specific encapsulation of isolated water molecules.

    PubMed

    Lavendomme, Roy; Marcélis, Lionel; Wouters, Johan; Luhmer, Michel; Jabin, Ivan

    2016-12-01

    A calix[4]arene-based molecular box was synthesized. Its properties were characterized through XRD and extensive NMR studies. This receptor is able to encapsulate specifically two isolated water molecules in both non-protic and protic solvents. This is a consequence of high size, geometric and electronic complementarity between the host and the water molecules.

  15. Key Role of Active-Site Water Molecules in Bacteriorhodopsin Proton-Transfer Reactions

    SciTech Connect

    Bondar, A.N.; Baudry, Jerome Y; Suhai, Sandor; Fischer, S.; Smith, Jeremy C

    2008-10-01

    The functional mechanism of the light-driven proton pump protein bacteriorhodopsin depends on the location of water molecules in the active site at various stages of the photocycle and on their roles in the proton-transfer steps. Here, free energy computations indicate that electrostatic interactions favor the presence of a cytoplasmic-side water molecule hydrogen bonding to the retinal Schiff base in the state preceding proton transfer from the retinal Schiff base to Asp85. However, the nonequilibrium nature of the pumping process means that the probability of occupancy of a water molecule in a given site depends both on the free energies of insertion of the water molecule in this and other sites during the preceding photocycle steps and on the kinetic accessibility of these sites on the time scale of the reaction steps. The presence of the cytoplasmic-side water molecule has a dramatic effect on the mechanism of proton transfer: the proton is channeled on the Thr89 side of the retinal, whereas the transfer on the Asp212 side is hindered. Reaction-path simulations and molecular dynamics simulations indicate that the presence of the cytoplasmic-side water molecule permits a low-energy bacteriorhodopsin conformer in which the water molecule bridges the twisted retinal Schiff base and the proton acceptor Asp85. From this low-energy conformer, proton transfer occurs via a concerted mechanism in which the water molecule participates as an intermediate proton carrier.

  16. Adsorption of Small Molecules at Water--Hexane and Water--Membrane Interfaces

    NASA Astrophysics Data System (ADS)

    Wilson, Michael A.

    1996-03-01

    The interaction of solutes with aqueous interfaces plays a significant role in a variety of physical processes, including general anesthesia and atmospheric chemistry. We present molecular dynamics results for the transfer of several small solutes across water liquid--vapor, water--hexane and water--GMO bilayer membrane interfaces. (A. Pohorille and M. A. Wilson, J. Chem. Phys. (in press, 1995).)^, (A. Pohorille, P. CIeplak, and M. A. Wilson, Chem. Phys. (in press, 1995).) The free energies of transferring small polar molecules across the interface exhibit fairly deep minima while those of nonpolar molecules do not. This is due to a balance between nonelectrostatic contributions --- primarily the work required to create a cavity large enough to accommodate the solute --- and the solute--solvent electrostatic interactions.^1 The surface excess of solute is calculated and compared with experimental results from the Gibbs adsorption isotherm. The interfacial solubilities correlate with measured anesthetic potencies of these compounds, implying that the binding sites for anesthetics are located near the water--membrane interface.

  17. Competitive Adsorption of Naphthenic Acids and Polyaromatic Molecules at a Toluene-Water Interface.

    PubMed

    Teklebrhan, Robel B; Jian, Cuiying; Choi, Phillip; Xu, Zhenghe; Sjöblom, Johan

    2016-12-22

    The early-stage competitive co-adsorption of interfacially active naphthenic acids (NAs) and polyaromatic (PA) molecules to a toluene-water interface from the bulk toluene phase was studied using molecular dynamics (MD) simulation. The NA molecules studied had the same polar functional group but different cycloaliphatic nonpolar tails, and a perylene bisimide (PBI)-based molecule was used as a representative PA compound. The results from our simulations suggest that the size and structural features of NA molecules greatly influence the interfacial activity of PA molecules and partitioning of NA molecules at the toluene-water interface. At low concentrations of PA (∼2.3 wt %) and NA (∼0.4 wt %) molecules, NA molecules containing large cycloaliphatic rings (e.g., four rings) or with a very long aliphatic tail (e.g., carbon chain length of 14) were observed to impede the migration of PA molecules to the interface, whereas small NA molecules containing two cycloaliphatic rings had little effect on the adsorption of PA molecules at the toluene-water interface. At high NA concentrations, the adsorption of PA molecules (∼5.75-17.25 wt %) was greatly hindered by the presence of small NA molecules (∼1.6-4.8 wt %) due to the solvation of PA nanoaggregates in the bulk. Adsorption mechanisms of PA and NA molecules at toluene-water interfaces were clarified through a detailed analysis on the interactions among different species in the system. The results obtained from this work provide insights into designing appropriate chemical demulsifiers or co-demulsifiers for breaking water-in-oil emulsions of great industrial applications.

  18. Subdivision of phase space for anisotropically interacting water molecules

    NASA Astrophysics Data System (ADS)

    Epifanov, S. Yu.; Vigasin, A. A.

    An efficient numerical algorithm is employed which enables one to perform multidimensional integrations of complicated integrands. Temperature dependence of the second virial coefficient for water is reproduced using the Matsuoka Clementi Yoshimine intermolecular water water potential. Metastable states are shown to occupy significant domain in the water dimer phase space.

  19. Multispectral actinometry of water and water-derivative molecules in moist, inert gas discharge plasmas

    NASA Astrophysics Data System (ADS)

    Bernatskiy, A. V.; Ochkin, V. N.; Kochetov, I. V.

    2016-10-01

    A new version of optical actinometry (OA) is used to determine the concentrations of water molecules and their fragments in hollow cathode discharge plasma in moist inert gases. Use is made of two actinometer particles, namely, the atoms Xe and Ar, for concurrent measurements of the concentrations of the H2O molecule and its fragments O, H, and OH. A self-consistent method is suggested for the determination of particle concentrations with due regard for the quenching of the emitting states. The temporal behavior of particles during discharge glow is studied. Noted are fast variations (lasting from a few to a few tens of s) in the concentrations of all the particles, followed by their stabilization (within a few to a few tens of mins). The scheme of the processes responsible for the observed dynamics of the plasma composition is discussed.

  20. Experimental Study of Water Cluster Molecules with Relevance to Mesospheric Clouds

    NASA Astrophysics Data System (ADS)

    Robertson, Scott; Sternovsky, Zoltan; Horanyi, Mihaly

    2000-10-01

    We have begun an experimental investigation of the properties of the water cluster molecules responsible for clouds occurring in the polar mesopause. These clusters disturb the charge balance in the ionosphere by attaching electrons which then creates localized reductions in the electron density. A supersonic nozzle sprays a mixture of water vapor and argon into vacuum and the expansion leads to condensation of clusters with 4 to 11 water molecules. Initial measurements are of the collision cross section of these molecules with neutral gas. The cross sections have a minimum at six waters consistent with the tighter molecular arrangement predicted for this cluster number. Additional measurements are underway for charging processes.

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

    SciTech Connect

    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.

  2. Effects of fluctuating river-pool stages on ground-water levels in the adjacent alluvial aquifer in the lower Arkansas River, Arkansas

    USGS Publications Warehouse

    Freiwald, D.A.; Grosz, G.D.

    1988-01-01

    The U.S. Geological Survey conducted a study in cooperation with the U.S. Army Corps of Engineers to determine the effect of fluctuating the lower Arkansas River. A network of 41 wells was used to delineate 4 cross sections adjacent to river pools 2 and 5 of the McClellan-Kerr Arkansas River Navigation System to examine groundwater levels at various distances from the river. The hydraulic gradient of water levels in the alluvial aquifer along these cross sections indicates that the river is losing water to the adjacent aquifer. The effect on groundwater levels in the alluvial aquifer caused by pool-stage fluctuations was most pronounced at distances less than about 2 miles from the Arkansas River. At distances greater than about 2 miles, the changes in groundwater levels probably were the result of water levels rising in the aquifer since the heavy summer irrigation withdrawals have ceased. An equation useful for estimating the distribution of head change an aquifer in response to river-pool-stage changes, was applied to the study area to estimate the effect of a 1-foot rise in pool stage on water levels in the adjacent alluvial aquifer after equilibrium conditions have been established. The theoretical head change (rise) in the aquifer was estimated to range from 1-foot at the Arkansas River to 0.57 foot at a distance of 5 miles away from the river. (USGS)

  3. Solvated water molecules and hydrogen-bridged networks in liquid water

    NASA Astrophysics Data System (ADS)

    Corongiu, Giorgina; Clementi, Enrico

    1993-02-01

    We have analyzed the molecular-dynamics (MD) trajectories for the oxygen and hydrogen atoms of liquid water, at six temperatures (from hot, T=361 K, to supercooled water, T=242 K); in the MD simulations the Nieser-Corongiu-Clementi ab initio potential has been used, since it yields reliable x-ray and neutron-diffraction data as well as infrared, Raman, and neutron-scattering spectra. Our analysis leads to two complementary models where we can consider each water as a solvated molecule (placed at the center of a solvation shell) or as a component of a cyclic polymer, a substructure of the hydrogen-bonded network. In the first solvation shell all water molecules are solvated with coordination values in the range 2-8. The most probable solvation number is four, at low temperature, and five at high temperature considering oxygen-oxygen pairs; however, the coordination number is four at all the temperatures if we consider oxygen-hydrogen pairs. The lifetime of the tetra coordinated complexes is the largest one and increases as temperature decreases. The computed population of cyclic polymers is highest for the pentameters in the studied temperature range, the second most probable cyclic structure is for hexamers. The average O-O distances in the liquid are temperature dependent and shorter than those in the gas phase, approaching ice values at low temperature (except for cyclic trimers, for which the O-O distance is nearly temperature independent). As a preliminary result, the lifetime of the polygons is estimated to be around 0.01 ps.

  4. Quantifying the entropy of binding for water molecules in protein cavities by computing correlations.

    PubMed

    Huggins, David J

    2015-02-17

    Protein structural analysis demonstrates that water molecules are commonly found in the internal cavities of proteins. Analysis of experimental data on the entropies of inorganic crystals suggests that the entropic cost of transferring such a water molecule to a protein cavity will not typically be greater than 7.0 cal/mol/K per water molecule, corresponding to a contribution of approximately +2.0 kcal/mol to the free energy. In this study, we employ the statistical mechanical method of inhomogeneous fluid solvation theory to quantify the enthalpic and entropic contributions of individual water molecules in 19 protein cavities across five different proteins. We utilize information theory to develop a rigorous estimate of the total two-particle entropy, yielding a complete framework to calculate hydration free energies. We show that predictions from inhomogeneous fluid solvation theory are in excellent agreement with predictions from free energy perturbation (FEP) and that these predictions are consistent with experimental estimates. However, the results suggest that water molecules in protein cavities containing charged residues may be subject to entropy changes that contribute more than +2.0 kcal/mol to the free energy. In all cases, these unfavorable entropy changes are predicted to be dominated by highly favorable enthalpy changes. These findings are relevant to the study of bridging water molecules at protein-protein interfaces as well as in complexes with cognate ligands and small-molecule inhibitors.

  5. Quantifying the Entropy of Binding for Water Molecules in Protein Cavities by Computing Correlations

    PubMed Central

    Huggins, David J.

    2015-01-01

    Protein structural analysis demonstrates that water molecules are commonly found in the internal cavities of proteins. Analysis of experimental data on the entropies of inorganic crystals suggests that the entropic cost of transferring such a water molecule to a protein cavity will not typically be greater than 7.0 cal/mol/K per water molecule, corresponding to a contribution of approximately +2.0 kcal/mol to the free energy. In this study, we employ the statistical mechanical method of inhomogeneous fluid solvation theory to quantify the enthalpic and entropic contributions of individual water molecules in 19 protein cavities across five different proteins. We utilize information theory to develop a rigorous estimate of the total two-particle entropy, yielding a complete framework to calculate hydration free energies. We show that predictions from inhomogeneous fluid solvation theory are in excellent agreement with predictions from free energy perturbation (FEP) and that these predictions are consistent with experimental estimates. However, the results suggest that water molecules in protein cavities containing charged residues may be subject to entropy changes that contribute more than +2.0 kcal/mol to the free energy. In all cases, these unfavorable entropy changes are predicted to be dominated by highly favorable enthalpy changes. These findings are relevant to the study of bridging water molecules at protein-protein interfaces as well as in complexes with cognate ligands and small-molecule inhibitors. PMID:25692597

  6. Energetics of displacing water molecules from protein binding sites: consequences for ligand optimization.

    PubMed

    Michel, Julien; Tirado-Rives, Julian; Jorgensen, William L

    2009-10-28

    A strategy in drug design is to consider enhancing the affinity of lead molecules with structural modifications that displace water molecules from a protein binding site. Because success of the approach is uncertain, clarification of the associated energetics was sought in cases where similar structural modifications yield qualitatively different outcomes. Specifically, free-energy perturbation calculations were carried out in the context of Monte Carlo statistical mechanics simulations to investigate ligand series that feature displacement of ordered water molecules in the binding sites of scytalone dehydratase, p38-alphaMAP kinase, and EGFR kinase. The change in affinity for a ligand modification is found to correlate with the ease of displacement of the ordered water molecule. However, as in the EGFR example, the binding affinity may diminish if the free-energy increase due to the removal of the bound water molecule is not more than compensated by the additional interactions of the water-displacing moiety. For accurate computation of the effects of ligand modifications, a complete thermodynamic analysis is shown to be needed. It requires identification of the location of water molecules in the protein-ligand interface and evaluation of the free-energy changes associated with their removal and with the introduction of the ligand modification. Direct modification of the ligand in free-energy calculations is likely to trap the ordered molecule and provide misleading guidance for lead optimization.

  7. Preliminary Geologic Map of the Southern Funeral Mountains and Adjacent Ground-Water Discharge Sites, Inyo County, California, and Nye County, Nevada

    USGS Publications Warehouse

    Fridrich, Christopher J.; Thompson, Ren A.; Slate, Janet L.; Berry, M.E.; Machette, Michael N.

    2008-01-01

    This map covers the southern part of the Funeral Mountains, and adjacent parts of four structural basins - Furnace Creek, Amargosa Valley, Opera House, and central Death Valley. It extends over three full 7.5-minute quadrangles, and parts of eleven others - a total area of about 950 square kilometers. The boundaries of this map were drawn to include all of the known proximal hydrogeologic features that may affect the flow of ground water that discharges from the springs of the Furnace Creek wash area, in the west-central part of the map. These springs provide the major potable water supply for Death Valley National Park.

  8. Benchmarking the thermodynamic analysis of water molecules around a model beta sheet.

    PubMed

    Huggins, David J

    2012-06-05

    Water molecules play a vital role in biological and engineered systems by controlling intermolecular interactions in the aqueous phase. Inhomogeneous fluid solvation theory provides a method to quantify solvent thermodynamics from molecular dynamics or Monte Carlo simulations and provides an insight into intermolecular interactions. In this study, simulations of TIP4P-2005 and TIP5P-Ewald water molecules around a model beta sheet are used to investigate the orientational correlations and predicted thermodynamic properties of water molecules at a protein surface. This allows the method to be benchmarked and provides information about the effect of a protein on the thermodynamics of nearby water molecules. The results show that the enthalpy converges with relatively little sampling, but the entropy and thus the free energy require considerably more sampling to converge. The two water models yield a very similar pattern of hydration sites, and these hydration sites have very similar thermodynamic properties, despite notable differences in their orientational preferences. The results also predict that a protein surface affects the free energy of water molecules to a distance of approximately 4.0 Å, which is in line with previous work. In addition, all hydration sites have a favorable free energy with respect to bulk water, but only when the water-water entropy term is included. A new technique for calculating this term is presented and its use is expected to be very important in accurately calculating solvent thermodynamics for quantitative application.

  9. Larval fish assemblages in a tropical mangrove estuary and adjacent coastal waters: Offshore-inshore flux of marine and estuarine species

    NASA Astrophysics Data System (ADS)

    Ooi, A. L.; Chong, V. C.

    2011-10-01

    A total of 92,934 fish larvae representing 19 families were sampled monthly from the Sangga Kecil estuary (Matang Mangrove Forest Reserve) and adjacent coastal waters from May 2002 to October 2003. Larval fish assemblages were numerically dominated by Gobiidae (50.1%) and Engraulidae (38.4%). Canonical Correspondence Analysis (CCA) revealed that the larval fish assemblages, including their ontogenetic stages, differed between the mangrove estuary and adjacent offshore waters, and that salinity, turbidity and zooplankton food are the major environmental factors structuring the larval fish assemblages. Estuarine preflexion gobiid larvae were ubiquitous in the coastal and estuarine waters. Larval stages of euryhaline species that were spawned in offshore waters, such as Engraulidae and Clupeidae, were largely advected into mangrove areas at the postflexion stages. Larvae of other euryhaline fishes (Sciaenidae, Blenniidae and Cynoglossidae) that may have been spawned inside the estuary were, however, exported to offshore waters. Given that the collective number of juvenile and adult fish families in the Matang estuary was 53, while the number of larval families was only 17, the former is quite disconnected from the existing larval fish population in the estuary.

  10. Relaxation dynamics of surface-adsorbed water molecules in nanoporous silica probed by terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Ru; Liu, Kao-Hsiang; Mou, Chung-Yuan; Sun, Chi-Kuang

    2015-08-01

    Relaxation dynamics of an exclusively adsorbed water molecule in mesoporous silica MCM-41-S was studied by using terahertz spectroscopy. With the temperature controlled from 0 to 50 °C, we observed strongly frequency- and temperature-dependent dielectric relaxation responses, implying that, unlike ice, surface-adsorbed water molecules retained flourishing picosecond dynamics. Based on the Debye relaxation model, a relaxation time constant was found to increase from 1.77 to 4.83 ps when the water molecule was cooled from 50 to 0 °C. An activation energy of ˜15 kJ/mol, which was in close agreement with a hydrogen-bonding energy, was further extracted from the Arrhenius analysis. Combined with previous molecular dynamics simulations, our results indicate that the reorientation relaxation originated from the "flip-flop" rotation of a three hydrogen-bonded surface-adsorbed water molecule.

  11. Quasielastic neutron scattering investigation of motion of water molecules in n-propyl alcohol-water mixture.

    PubMed

    Nakada, Masaru; Maruyama, Kenji; Yamamuro, Osamu; Misawa, Masakatsu

    2009-02-21

    The dynamics of water molecules in the n-propyl alcohol-water mixtures is investigated by using quasielastic neutron scattering measurements. The dynamic structure factor S(Q,E) obtained from incoherent scattering of hydrogen atoms of water is fitted with jump diffusion and relaxing cage models. The diffusion constant obtained from the relaxing cage model, which gives better fitting with S(Q,E), shows better agreement to the experimental value than that of jump diffusion model. The dependence of translational relaxation time tau(T)(Q) and stretched exponent beta(T)(Q) on the fraction of hydrophobic hydrating water molecules in the solution is discussed.

  12. Quasielastic neutron scattering investigation of motion of water molecules in n-propyl alcohol-water mixture

    NASA Astrophysics Data System (ADS)

    Nakada, Masaru; Maruyama, Kenji; Yamamuro, Osamu; Misawa, Masakatsu

    2009-02-01

    The dynamics of water molecules in the n-propyl alcohol-water mixtures is investigated by using quasielastic neutron scattering measurements. The dynamic structure factor S(Q,E) obtained from incoherent scattering of hydrogen atoms of water is fitted with jump diffusion and relaxing cage models. The diffusion constant obtained from the relaxing cage model, which gives better fitting with S(Q,E), shows better agreement to the experimental value than that of jump diffusion model. The dependence of translational relaxation time τT(Q) and stretched exponent βT(Q) on the fraction of hydrophobic hydrating water molecules in the solution is discussed.

  13. Clustering of water molecules in ultramicroporous carbon: In-situ small-angle neutron scattering

    SciTech Connect

    Bahadur, Jitendra; Contescu, Cristian I.; Rai, Durgesh K.; Gallego, Nidia C.; Melnichenko, Yuri B.

    2016-10-19

    The adsorption of water is central to most of the applications of microporous carbon as adsorbent material. We report early kinetics of water adsorption in the microporous carbon using in-situ small-angle neutron scattering. It is observed that adsorption of water occurs via cluster formation of molecules. Interestingly, the cluster size remains constant throughout the adsorption process whereas number density of clusters increases with time. The role of surface chemistry of microporous carbon on the early kinetics of adsorption process was also investigated. Lastly, the present study provides direct experimental evidence for cluster assisted adsorption of water molecules in microporous carbon (Do-Do model).

  14. Affinity transformation from hydrophilicity to hydrophobicity of water molecules on the basis of adsorption of water in graphitic nanopores.

    PubMed

    Ohba, Tomonori; Kanoh, Hirofumi; Kaneko, Katsumi

    2004-02-11

    The interaction of water with hydrophobic surfaces is quite important in a variety of chemical and biochemical phenomena. The coexistence of water and oil can be realized by introduction of surfactants. In the case of water vapor adsorption on graphitic nanopores, plenty of water can be adsorbed in graphitic nanopores without surfactants, although the graphitic surface is not hydrophilic. Why are water molecules adsorbed in hydrophobic nanopores remarkably? This work can give an explicit insight to water adsorption in hydrophobic graphite nanopores using experimental and theoretical approaches. Water molecules are associated with each other to form the cluster of 1 nm in size, leading to a significant stabilization of the cluster in the graphitic nanopores. This mechanism can be widely applied to interfacial phenomena relating to coexistence of water and nanostructural materials of hydrophobicity.

  15. Availability and chemistry of ground water on the Bruneau Plateau and adjacent eastern plain in Twin Falls County, south-central Idaho

    USGS Publications Warehouse

    Moffatt, R.L.; Jones, M.L.

    1984-01-01

    The Bruneau plateau in south-central Idaho consists of about 889 ,600 acres of potentially irrigable land. About 112,200 of these acres have been developed for agriculture; 11,200 acres are irrigated with ground water, and the remaining acreage is irrigated with water from the Snake and Bruneau rivers and Salmon Falls Creek. On the basis of present usage, about 158,000 acre-feet of water per year are needed to develop an additional 63,000 acres. About 438,000 acre-feet per year are needed to irrigate existing and newly developed lands in dry years when streamflow in the Snake River at Milner Dam is inadequate to meet appropriated needs. Pumping lifts of about 400-600 feet and low well yields on the Bruneau plateau probably preclude large-scale irrigation development solely from local ground-water resources. However, supplemental sources of irrigation water are available from a perched-water aquifer, a thermal aquifer, and the regional aquifer adjacent to the plateau. About 100,000-115,000 acre-feet per year of water probably could be withdrawn from the perched and regional aquifers and conveyed to the plateau without serious impact on local ground-water resources. The amount of water that could be safely withdrawn from the thermal aquifer was not determined. (USGS)

  16. The role of water molecules in stereoselectivity of glucose/galactose-binding protein

    NASA Astrophysics Data System (ADS)

    Kim, Minsup; Cho, Art E.

    2016-11-01

    Using molecular dynamics (MD) simulation methods, we attempted to explain the experimental results on ligand specificity of glucose/galactose-binding protein (GGBP) to β-D-glucose and β-D-galactose. For the simulation, a three-dimensional structure of GGBP was prepared, and homology modeling was performed to generate variant structures of GGBP with mutations at Asp14. Then, docking was carried out to find a reasonable β-D-glucose and β-D-galactose binding conformations with GGBP. Subsequent molecular dynamics simulations of β-D-glucose–GGBP and β-D-galactose–GGBP complexes and estimation of the orientation and stability of water molecules at the binding site revealed how water molecules influence ligand specificity. In our simulation, water molecules mediated interactions of β-D-glucose or β-D-galactose with residue 14 of GGBP. In this mechanism, the Phe16Ala mutant leaves both sugar molecules free to move, and the specific role of water molecules were eliminated, while the wild type, Asp14Asn mutant, and Asp14Glu mutant make hydrogen bond interactions with β-D-glucose more favorable. Our results demonstrate that bound water molecules at the binding site of GGBP are related to localized conformational change, contributing to ligand specificity of GGBP for β-D-glucose over β-D-galactose.

  17. Development of ground-water resources in Orange County, Texas, and adjacent areas in Texas and Louisiana, 1971-80

    USGS Publications Warehouse

    Bonnet, C.W.; Gabrysch, R.K.

    1982-01-01

    Although saltwater encroachment is evident in parts of southern Orange County, the encroachment is not expected to be detrimental if the ground-water pumping remains stable and the projected increase in demands for water is met with surface-water supplies.

  18. Conceptualization and analysis of ground-water flow system in the Coastal Plain of Virginia and adjacent parts of Maryland and North Carolina

    USGS Publications Warehouse

    Harsh, John F.; Laczniak, Randell J.

    1990-01-01

    The ground-water flow system in the Coastal Plain of Virginia and adjacent parts of Maryland and North Carolina consists of a water table aquifer and an underlying sequence of confined aquifers and intervening confining units composed of unconsolidated sand and clay. A digital flow model was developed to enhance knowledge of the behavior of the ground-water flow system in response to its development. Ten pumping periods covering 90 yr of withdrawal simulated the history of ground-water development. Simulated potentiometric-surface maps for 1980 show lowered water levels and the development of coalescing cones of depression around the cities of Franklin, Suffolk, and Williamsburg and the town of West Point, all in Virginia. The largest simulated decline in water level, about 210 ft was near Franklin. Water budgets indicate that over the period of simulation (1891-1980): (1) pumpage from the model area increased by about 105 Mgal/d; (2) lateral boundary outflow increased by about 5 Mgal/d; (3) ground-water flow to streams and coastal water decreased by about 107.5 Mgal/d; (4) lateral boundary inflow increased by about 0.7 Mgal/d, and (5) water released from aquifer storage increased by about 1.6 Mgal/d. Simulated rates of recharge into the confined aquifer system at the end of the final pumping period (1980) varied up to 3.8 in/yr. and simulated rates of discharge out of the confined system varied up to 2.2 in/yr. Results of simulations show an increase of about 110 Mgal/d into the confined system from the unconfined system over the period of simulation. This increase in flow into the confined system affected local discharge of ground water to streams and regional discharge to coastal water. Lowering the storage coefficient of the aquifer had a minimal effect simulated water levels, whereas increasing the storage coefficient had a much more significant effect.

  19. Water-quality, bed-sediment, and discharge data for the Mississippi River-Gulf Outlet and adjacent waterways, southeastern Louisiana, August 2008 through December 2009

    USGS Publications Warehouse

    Swarzenski, Christopher M.; Mize, Scott V.; Lovelace, John K.

    2012-01-01

    The Mississippi River-Gulf Outlet navigation channel (MRGO) was constructed in the early 1960s to provide a safer and shorter route between the Gulf of Mexico and the Port of New Orleans for deep-draft, ocean-going vessels and to promote the economic development of the Port of New Orleans. In 2006, the U.S. Army Corps of Engineers developed a plan to de-authorize the MRGO. The plan called for a rock barrier to be constructed across the MRGO near Bayou La Loutre. In 2008, the U.S. Geological Survey, in cooperation with the Louisiana Coastal Area Science and Technology Program began a study to document the impacts of the rock barrier on water-quality and flow before, during, and after its construction. Water-quality, bed-sediment, and discharge data were collected in the MRGO and adjacent water bodies from August 2008 through December 2009.

  20. Literature and data review for the surface-water pathway: Columbia River and adjacent coastal areas. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Walters, W.H.; Dirkes, R.L.; Napier, B.A.

    1992-11-01

    As part of the Hanford Environmental Dose Reconstruction (HEDR) Project, Battelle, Pacific Northwest Laboratories reviewed literature and data on radionuclide concentrations and distribution in the water, sediment, and biota of the Columbia River and adjacent coastal areas. Over 600 documents were reviewed including Hanford reports, reports by offsite agencies, journal articles, and graduate theses. Radionuclide concentration data were used in preliminary estimates of individual dose for the period 1964 through 1966. This report summarizes the literature and database reviews and the results of the preliminary dose estimates.

  1. Literature and data review for the surface-water pathway: Columbia River and adjacent coastal areas. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Walters, W.H.; Dirkes, R.L.; Napier, B.A.

    1992-04-01

    As part of the Hanford Environmental Dose Reconstruction Project, Pacific Northwest Laboratory reviewed literature and data on radionuclide concentrations and distribution in the water, sediment, and biota of the Columbia River and adjacent coastal areas. Over 600 documents were reviewed including Hanford reports, reports by offsite agencies, journal articles, and graduate theses. Certain radionuclide concentration data were used in preliminary estimates of individual dose for the 1964--1966 time period. This report summarizes the literature and database review and the results of the preliminary dose estimates.

  2. Depositional and diagenetic history and petroleum geology of the Jurassic Norphlet Formation of the Alabama coastal waters area and adjacent federal waters area

    USGS Publications Warehouse

    Kugler, R.L.; Mink, R.M.

    1999-01-01

    The discovery of deep (>20,000 ft) gas reservoirs in eolian sandstone of the Upper Jurassic Norphlet Formation in Mobile Bay and offshore Alabama in the late 1970s represents one of the most significant hydrocarbon discoveries in the nation during the past several decades. Estimated original proved gas from Norphlet reservoirs in the Alabama coastal waters and adjacent federal waters is 7.462 trillion ft3 (Tcf) (75% recovery factor). Fifteen fields have been established in the offshore Alabama area. Norphlet sediment was deposited in an arid environment in alluvial fans, alluvial plains, and wadis in updip areas. In downdip areas, the Norphlet was deposited in a broad desert plain, with erg development in some areas. Marine transgression, near the end of Norphlet deposition, resulted in reworking of the upper part of the Norphlet Formation. Norphlet reservoir sandstone is arkose and subarkose, consisting of a simple assemblage of three minerals, quartz, albite, and K-feldspar. The present framework grain assemblage of the Norphlet is dominantly diagenetic, owing to albitization and dissolution of feldspar. Despite the simple framework composition, the diagenetic character of the Norphlet is complex. Important authigenic minerals include carbonate phases (calcite, dolomite, Fe-dolomite, and breunnerite), feldspar (albite and K-feldspar), evaporite minerals (anhydrite and halite), clay minerals (illite and chlorite), quartz, and pyrobitumen. The abundance and distribution of these minerals varies significantly between onshore and offshore regions of Norphlet production. The lack of sufficient internal sources of components for authigenic minerals, combined with unusual chemical compositions of chloride (Mg-rich), breunnerite, and some minor authigenic minerals, suggests that Louann-derived fluids influenced Norphlet diagenesis. In offshore Alabama reservoirs, porosity is dominantly modified primary porosity. Preservation of porosity in deep Norphlet reservoirs is due

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

    PubMed

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-06-21

    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.

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

    PubMed Central

    Gorshunov, B. P.; Torgashev, V. I.; Zhukova, E. S.; Thomas, V. G.; Belyanchikov, M. A.; Kadlec, C.; Kadlec, F.; Savinov, M.; Ostapchuk, T.; Petzelt, J.; 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

    Water is characterized by large molecular electric dipole moments and strong interactions between molecules; however, hydrogen bonds screen the dipole–dipole coupling and suppress the ferroelectric order. The situation changes drastically when water is confined: in this case ordering of the molecular dipoles has been predicted, but never unambiguously detected experimentally. In the present study we place separate H2O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole–dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem. We observe a ferroelectric soft mode that causes Curie–Weiss behaviour of the static permittivity, which saturates below 10 K due to quantum fluctuations. The ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices. PMID:27687693

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

    NASA Astrophysics Data System (ADS)

    Gorshunov, B. P.; Torgashev, V. I.; Zhukova, E. S.; Thomas, V. G.; Belyanchikov, M. A.; Kadlec, C.; Kadlec, F.; Savinov, M.; Ostapchuk, T.; Petzelt, J.; 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.

    2016-09-01

    Water is characterized by large molecular electric dipole moments and strong interactions between molecules; however, hydrogen bonds screen the dipole-dipole coupling and suppress the ferroelectric order. The situation changes drastically when water is confined: in this case ordering of the molecular dipoles has been predicted, but never unambiguously detected experimentally. In the present study we place separate H2O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole-dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem. We observe a ferroelectric soft mode that causes Curie-Weiss behaviour of the static permittivity, which saturates below 10 K due to quantum fluctuations. The ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices.

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

    PubMed

    Gorshunov, B P; Torgashev, V I; Zhukova, E S; Thomas, V G; Belyanchikov, M A; Kadlec, C; Kadlec, F; Savinov, M; Ostapchuk, T; Petzelt, J; 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

    2016-09-30

    Water is characterized by large molecular electric dipole moments and strong interactions between molecules; however, hydrogen bonds screen the dipole-dipole coupling and suppress the ferroelectric order. The situation changes drastically when water is confined: in this case ordering of the molecular dipoles has been predicted, but never unambiguously detected experimentally. In the present study we place separate H2O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole-dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem. We observe a ferroelectric soft mode that causes Curie-Weiss behaviour of the static permittivity, which saturates below 10 K due to quantum fluctuations. The ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices.

  7. Auger spectrum of a water molecule after single and double core ionization.

    PubMed

    Inhester, L; Burmeister, C F; Groenhof, G; Grubmüller, H

    2012-04-14

    The high intensity of free electron lasers opens up the possibility to perform single-shot molecule scattering experiments. However, even for small molecules, radiation damage induced by absorption of high intense x-ray radiation is not yet fully understood. One of the striking effects which occurs under intense x-ray illumination is the creation of double core ionized molecules in considerable quantity. To provide insight into this process, we have studied the dynamics of water molecules in single and double core ionized states by means of electronic transition rate calculations and ab initio molecular dynamics (MD) simulations. From the MD trajectories, photoionization and Auger transition rates were computed based on electronic continuum wavefunctions obtained by explicit integration of the coupled radial Schrödinger equations. These rates served to solve the master equations for the populations of the relevant electronic states. To account for the nuclear dynamics during the core hole lifetime, the calculated electron emission spectra for different molecular geometries were incoherently accumulated according to the obtained time-dependent populations, thus neglecting possible interference effects between different decay pathways. We find that, in contrast to the single core ionized water molecule, the nuclear dynamics for the double core ionized water molecule during the core hole lifetime leaves a clear fingerprint in the resulting electron emission spectra. The lifetime of the double core ionized water was found to be significantly shorter than half of the single core hole lifetime.

  8. Auger spectrum of a water molecule after single and double core ionization

    SciTech Connect

    Inhester, L.; Burmeister, C. F.; Groenhof, G.; Grubmueller, H.

    2012-04-14

    The high intensity of free electron lasers opens up the possibility to perform single-shot molecule scattering experiments. However, even for small molecules, radiation damage induced by absorption of high intense x-ray radiation is not yet fully understood. One of the striking effects which occurs under intense x-ray illumination is the creation of double core ionized molecules in considerable quantity. To provide insight into this process, we have studied the dynamics of water molecules in single and double core ionized states by means of electronic transition rate calculations and ab initio molecular dynamics (MD) simulations. From the MD trajectories, photoionization and Auger transition rates were computed based on electronic continuum wavefunctions obtained by explicit integration of the coupled radial Schroedinger equations. These rates served to solve the master equations for the populations of the relevant electronic states. To account for the nuclear dynamics during the core hole lifetime, the calculated electron emission spectra for different molecular geometries were incoherently accumulated according to the obtained time-dependent populations, thus neglecting possible interference effects between different decay pathways. We find that, in contrast to the single core ionized water molecule, the nuclear dynamics for the double core ionized water molecule during the core hole lifetime leaves a clear fingerprint in the resulting electron emission spectra. The lifetime of the double core ionized water was found to be significantly shorter than half of the single core hole lifetime.

  9. Molecular Dynamics Study of Small PNA Molecules in Lipid-Water System

    PubMed Central

    Weroński, Paweł; Jiang, Yi; Rasmussen, Steen

    2007-01-01

    We present the results of molecular dynamics simulations of small peptide nucleic acid (PNA) molecules, synthetic analogs of DNA, at a lipid bilayer in water. At neutral pH, without any salt, and in the NPnγT ensemble, two similar PNA molecules (6-mers) with the same nucleic base sequence and different terminal groups are investigated at the interface between water and a 1-palmitoyl-2-oleoylphosphatidylcholine lipid bilayer. The results of our simulations suggest that at low ionic strength of the solution, both PNA molecules adsorb at the lipid-water interface. In the case where the PNA molecule has charged terminal groups, the main driving force of adsorption is the electrostatic attraction between the charged groups of PNA and the lipid heads. The main driving force of adsorption of the PNA molecule with neutral terminal groups is the hydrophobic interaction of the nonpolar groups. Our simulations suggest that the system free energy change associated with PNA adsorption at the lipid-water interface is on the order of several tens of kT per PNA molecule in both cases. PMID:17307825

  10. Vibrational states of a water molecule in a nano-cavity of beryl crystal lattice.

    PubMed

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

    2014-06-14

    Low-energy excitations of a single water molecule are studied when confined within a nano-size cavity formed by the ionic crystal lattice. Optical spectra are measured of manganese doped beryl single crystal Mn:Be3Al2Si6O18, that contains water molecules individually isolated in 0.51 nm diameter voids within the crystal lattice. Two types of orientation are distinguished: water-I molecules have their dipole moments aligned perpendicular to the c axis and dipole moments of water-II molecules are parallel to the c-axis. The optical conductivity σ(ν) and permittivity ɛ'(ν) spectra are recorded in terahertz and infrared ranges, at frequencies from several wavenumbers up to ν = 7000 cm(-1), at temperatures 5-300 K and for two polarizations, when the electric vector E of the radiation is parallel and perpendicular to the c-axis. Comparative experiments on as-grown and on dehydrated samples allow to identify the spectra of σ(ν) and ɛ'(ν) caused exclusively by water molecules. In the infrared range, well-known internal modes ν1, ν2, and ν3 of the H2O molecule are observed for both polarizations, indicating the presence of water-I and water-II molecules in the crystal. Spectra recorded below 1000 cm(-1) reveal a rich set of highly anisotropic features in the low-energy response of H2O molecule in a crystalline nano-cavity. While for E∥c only two absorption peaks are detected, at ~90 cm(-1) and ~160 cm(-1), several absorption bands are discovered for E⊥c, each consisting of narrower resonances. The bands are assigned to librational (400-500 cm(-1)) and translational (150-200 cm(-1)) vibrations of water-I molecule that is weakly coupled to the nano-cavity "walls." A model is presented that explains the "fine structure" of the bands by a splitting of the energy levels due to quantum tunneling between the minima in a six-well potential relief felt by a molecule within the cavity.

  11. Vibrational states of a water molecule in a nano-cavity of beryl crystal lattice

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Low-energy excitations of a single water molecule are studied when confined within a nano-size cavity formed by the ionic crystal lattice. Optical spectra are measured of manganese doped beryl single crystal Mn:Be3Al2Si6O18, that contains water molecules individually isolated in 0.51 nm diameter voids within the crystal lattice. Two types of orientation are distinguished: water-I molecules have their dipole moments aligned perpendicular to the c axis and dipole moments of water-II molecules are parallel to the c-axis. The optical conductivity σ(ν) and permittivity ɛ'(ν) spectra are recorded in terahertz and infrared ranges, at frequencies from several wavenumbers up to ν = 7000 cm-1, at temperatures 5-300 K and for two polarizations, when the electric vector E of the radiation is parallel and perpendicular to the c-axis. Comparative experiments on as-grown and on dehydrated samples allow to identify the spectra of σ(ν) and ɛ'(ν) caused exclusively by water molecules. In the infrared range, well-known internal modes ν1, ν2, and ν3 of the H2O molecule are observed for both polarizations, indicating the presence of water-I and water-II molecules in the crystal. Spectra recorded below 1000 cm-1 reveal a rich set of highly anisotropic features in the low-energy response of H2O molecule in a crystalline nano-cavity. While for E∥c only two absorption peaks are detected, at ˜90 cm-1 and ˜160 cm-1, several absorption bands are discovered for E⊥c, each consisting of narrower resonances. The bands are assigned to librational (400-500 cm-1) and translational (150-200 cm-1) vibrations of water-I molecule that is weakly coupled to the nano-cavity "walls." A model is presented that explains the "fine structure" of the bands by a splitting of the energy levels due to quantum tunneling between the minima in a six-well potential relief felt by a molecule within the cavity.

  12. Water and Small-Molecule Permeation of Dormant Bacillus subtilis Spores

    PubMed Central

    Cermak, Nathan; Feijó Delgado, Francisco; Setlow, Barbara; Setlow, Peter

    2015-01-01

    ABSTRACT We use a suspended microchannel resonator to characterize the water and small-molecule permeability of Bacillus subtilis spores based on spores' buoyant mass in different solutions. Consistent with previous results, we found that the spore coat is not a significant barrier to small molecules, and the extent to which small molecules may enter the spore is size dependent. We have developed a method to directly observe the exchange kinetics of intraspore water with deuterium oxide, and we applied this method to wild-type spores and a panel of congenic mutants with deficiencies in the assembly or structure of the coat. Compared to wild-type spores, which exchange in approximately 1 s, several coat mutant spores were found to have relatively high water permeability with exchange times below the ∼200-ms temporal resolution of our assay. In addition, we found that the water permeability of the spore correlates with the ability of spores to germinate with dodecylamine and with the ability of TbCl3 to inhibit germination with l-valine. These results suggest that the structure of the coat may be necessary for maintaining low water permeability. IMPORTANCE Spores of Bacillus species cause food spoilage and disease and are extremely resistant to standard decontamination methods. This hardiness is partly due to spores' extremely low permeability to chemicals, including water. We present a method to directly monitor the uptake of molecules into B. subtilis spores by weighing spores in fluid. The results demonstrate the exchange of core water with subsecond resolution and show a correlation between water permeability and the rate at which small molecules can initiate or inhibit germination in coat-damaged spores. The ability to directly measure the uptake of molecules in the context of spores with known structural or genetic deficiencies is expected to provide insight into the determinants of spores' extreme resistance. PMID:26483518

  13. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    USGS Publications Warehouse

    Welch, Alan H.; Bright, Daniel J.; Knochenmus, Lari A.

    2008-01-01

    INTRODUCTION This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 301(e) of the Lincoln County Conservation, Recreation, and Development Act of 2004; PL108-424) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins are the subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas are the subdivision used for reporting summed and tabulated subbasin estimates.

  14. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah - Draft Report

    USGS Publications Warehouse

    Welch, Alan H.; Bright, Daniel J.

    2007-01-01

    Summary of Major Findings This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 131 of the Lincoln County Conservation, Recreation, and Development Act of 2004) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins represent subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas represent the subdivision used for reporting summed and tabulated subbasin estimates.

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

    SciTech Connect

    McDowell, R.S.; Kossiakoff, A.A.

    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.

  16. Water molecules inside protein structure affect binding of monosaccharides with HIV-1 antibody 2G12.

    PubMed

    Ueno-Noto, Kaori; Takano, Keiko

    2016-10-05

    Water molecules inside biomolecules constitute integral parts of their structure and participate in the functions of the proteins. Some of the X-ray crystallographic data are insufficient for analyzing a series of ligand-protein complexes in the same condition. We theoretically investigated antibody binding abilities of saccharide ligands and the effects of the inner water molecules of ligand-antibody complexes. Classical molecular dynamics and quantum chemical simulations using a model with possible water molecules inside the protein were performed with saccharide ligands and Human Immunodeficiency Virus 1 neutralizing antibody 2G12 complexes to estimate how inner water molecules of the protein affect the dynamics of the complexes as well as the ligand-antibody interaction. Our results indicate the fact that d-fructose's strong affinity to the antibody was partly due to the good retentiveness of solvent water molecules of the ligand and its stability of the ligand's conformation and relative position in the active site. © 2016 Wiley Periodicals, Inc.

  17. Characteristics of the δ ^{15} N_{NO_3 } distribution and its drivers in the Changjiang River estuary and adjacent waters

    NASA Astrophysics Data System (ADS)

    Wang, Wentao; Yu, Zhiming; Song, Xiuxian; Wu, Zaixing; Yuan, Yongquan; Zhou, Peng; Cao, Xihua

    2017-03-01

    In this study, we conducted investigations in the Changjiang (Yangtze) River estuary and adjacent waters (CREAW) in June and November of 2014. We collected water samples from different depths to analyze the nitrogen isotopic compositions of nitrate, nutrient concentrations (including inorganic N, P, and Si), and other physical and biological parameters, along with the vertical distribution and seasonal variations of these parameters. The compositions of nitrogen isotope in nitrate were measured with the denitrifier method. Results show that the Changjiang River diluted water (CDW) was the main factor affecting the shallow waters (above 10 m) of the CREAW, and CDW tended to influence the northern areas in June and the southern areas in November. δ ^{15} N_{NO_3 } values in CDW ranged from 3.21‰-3.55‰. In contrast, the deep waters (below 30 m) were affected by the subsurface water of the Kuroshio Current, which intruded into the waters near 31°N in June. The δ ^{15} N_{NO_3 } values of these waters were 6.03‰-7.6‰, slightly higher than the values of the Kuroshio Current. Nitrate assimilation by phytoplankton in the shallow waters of the study area varied seasonally. Because of the favorable temperature and nutrient conditions in June, abundant phytoplankton growth resulted in harmful algae blooms (HABs). Therefore, nitrate assimilation was strong in June and weak in November. The δ ^{15} N_{NO_3 } fractionations caused by assimilation of phytoplankton were 4.57‰ and 4.41‰ in the shallow waters in June and November, respectively. These results are consistent with previous laboratory cultures and in situ investigations. Nitrification processes were observed in some deep waters of the study area, and they were more apparent in November than in June. The fractionation values of nitrification ranged from 24‰-25‰, which agrees with results for Nitrosospira tenuis reported by previous studies.

  18. Characteristics of the δ ^{15} N_{NO_3 } distribution and its drivers in the Changjiang River estuary and adjacent waters

    NASA Astrophysics Data System (ADS)

    Wang, Wentao; Yu, Zhiming; Song, Xiuxian; Wu, Zaixing; Yuan, Yongquan; Zhou, Peng; Cao, Xihua

    2016-05-01

    In this study, we conducted investigations in the Changjiang (Yangtze) River estuary and adjacent waters (CREAW) in June and November of 2014. We collected water samples from different depths to analyze the nitrogen isotopic compositions of nitrate, nutrient concentrations (including inorganic N, P, and Si), and other physical and biological parameters, along with the vertical distribution and seasonal variations of these parameters. The compositions of nitrogen isotope in nitrate were measured with the denitrifier method. Results show that the Changjiang River diluted water (CDW) was the main factor aff ecting the shallow waters (above 10 m) of the CREAW, and CDW tended to influence the northern areas in June and the southern areas in November. δ ^{15} N_{NO_3 } values in CDW ranged from 3.21‰-3.55‰. In contrast, the deep waters (below 30 m) were aff ected by the subsurface water of the Kuroshio Current, which intruded into the waters near 31°N in June. The δ ^{15} N_{NO_3 } values of these waters were 6.03‰-7.6‰, slightly higher than the values of the Kuroshio Current. Nitrate assimilation by phytoplankton in the shallow waters of the study area varied seasonally. Because of the favorable temperature and nutrient conditions in June, abundant phytoplankton growth resulted in harmful algae blooms (HABs). Therefore, nitrate assimilation was strong in June and weak in November. The δ ^{15} N_{NO_3 } fractionations caused by assimilation of phytoplankton were 4.57‰ and 4.41‰ in the shallow waters in June and November, respectively. These results are consistent with previous laboratory cultures and in situ investigations. Nitrification processes were observed in some deep waters of the study area, and they were more apparent in November than in June. The fractionation values of nitrification ranged from 24‰-25‰, which agrees with results for Nitrosospira tenuis reported by previous studies.

  19. Electrical-driven transport of endohedral fullerene encapsulating a single water molecule.

    PubMed

    Xu, Baoxing; Chen, Xi

    2013-04-12

    Encapsulating a single water molecule inside an endohedral fullerene provides an opportunity for manipulating the H2O@C60 through the encapsulated polar H2O molecule. Using molecular dynamic simulations, we propose a strategy of electrical-driven transport of H2O@C60 inside a channel, underpinned by the unique behavior of a water molecule free from a hydrogen-bonding environment. When an external electrical field is applied along the channel's axial direction, steady-state transport of H2O@C60 can be reached. The transport direction and rate depend on the applied electrical intensity as well as the polar orientation of the encapsulated H2O molecule.

  20. Utilization by fishes of the Alviso Island ponds and adjacent waters in south san francisco bay following restoration to tidal influence

    USGS Publications Warehouse

    Saiki, M.K.; Mejia, F.H.

    2009-01-01

    Earthen levees of three isolated salt ponds known locally as the Alviso Island Ponds were intentionally breached in March 2006 to allow tidal exchange of the ponds with water from Coyote Creek. The water exchange transformed the previously fishless hypersaline ponds into lower salinity habitats suitable for fish life. This study documented fish utilization of the ponds, adjacent reaches of Coyote Creek, and an upstream reach in nearby Artesian Slough during May-July 2006. By the time the study was initiated, water quality conditions in the ponds were similar to conditions in adjacent reaches of Coyote Creek. The only variable exhibiting a strong gradient within the study area was salinity, which increased progressively from upstream to downstream in Coyote Creek. A total of 4,034 fish represented by 18 species from 14 families was caught during the study. Judging from cluster analysis of presence-absence data that excluded rare fish species, the 10 sampling units (3 ponds, 6 reaches in Coyote Creek, and 1 reach in Artesian Slough) formed two clusters or groups, suggesting two species assemblages. The existence of two groups was also suggested by ordination with non-metric multidimensional scaling (NMS). One group, which was composed of the three ponds and four of the lowermost reaches of Coyote Creek, was characterized by mostly estuarine or marine species (e.g., topsmelt, Atherinops affinis; northern anchovy, Engraulis mordax; and longjaw mudsucker, Gillichthys mirabilis). The second group, which was composed of the two uppermost reaches of Coyote Creek and the one reach of Artesian Slough, was characterized by freshwater species (e.g., Sacramento sucker, Catostomus occidentalis) and by an absence of the estuarine/marine species noted in the first assemblage. Judging from a joint plot of selected water quality variables overlaying the ordination results, salinity was the only important variable associated with spatial distribution of fish species. Water

  1. Fish diversity in the Río de la Plata and adjacent waters: an overview of environmental influences on its spatial and temporal structure.

    PubMed

    Jaureguizar, A J; Solari, A; Cortés, F; Milessi, A C; Militelli, M I; Camiolo, M D; Luz Clara, M; García, M

    2016-07-01

    The fish diversity and the main environmental factors affecting the spatial distribution of species, life history stages and community structure in the Río de la Plata (RdP) and adjacent waters are reviewed and analysed, with emphasis on the functional guild classification. The functional guild classification indicated that most species in the RdP were marine stragglers, zoobenthivores and oviparous species, although the biomass was dominated by estuarine species. Salinity had a stronger influence than temperature on the spatial pattern for all life stages, shallower and fresher waters are the preferred habitats of neonates and juveniles. During the breeding season (spring-summer), adults showed an intrusion into the inner part of RdP or to its adjacent nearshore waters from the offshore waters for spawning or mating, respectively. Variations in river discharge and wind patterns greatly affected the spatial extent of estuarine water, which ultimately influenced the domain of the main life-history stages (juveniles or adults) for both marine and estuarine fishes, as well as species and fish assemblage composition. The strong environmental gradient restricts some species and life-history stages to a particular section and defines three main fish assemblage areas. The composition of the fish assemblage is indicative of the recruitment of freshwater and marine species to the estuary in opposite ways, determined by the vertical stratification. Seasonal changes in the species composition were related to migration as a result of salinity and temperature variations and reproductive migrations to spawning and mating areas. This overview reveals that the RdP is under environmental variations that are likely to produce modifications to fish distribution and abundance that affect its fisheries. This context plus fish stock declines and changes in exploitation patterns could amplify the magnitude of the variations in the fisheries resources availability and affect the

  2. Molecules, water, and radiant energy: new clues for the origin of life.

    PubMed

    Pollack, Gerald H; Figueroa, Xavier; Zhao, Qing

    2009-03-27

    We here examine the putative first step in the origin of life: the coalescence of dispersed molecules into a more condensed, organized state. Fresh evidence implies that the driving energy for this coalescence may come in a manner more direct than previously thought. The sun's radiant energy separates charge in water, and this free charge demonstrably induces condensation. This condensation mechanism puts water as a central protagonist in life rather than as an incidental participant, and thereby helps explain why life requires water.

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

    PubMed

    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.

  4. Influence of Aromatic Molecules on the Structure and Spectroscopy of Water Clusters

    NASA Astrophysics Data System (ADS)

    Tabor, Daniel P.; Sibert, Edwin; Walsh, Patrick S.; Zwier, Timothy S.

    2016-06-01

    Isomer-specific resonant ion-dip infrared spectra are presented for benzene-(water)_n, 1-2-diphenoxyethane-(water)_n, and tricyclophane-(water)_n clusters. The IR spectra are modeled with a local mode Hamiltonian that was originally formulated for the analysis of benzene-(water)_n clusters with up to seven waters. The model accounts for stretch-bend Fermi coupling, which can complicate the IR spectra in the 3150-3300 cm-1 region. When the water clusters interact with each of the solutes, the hydrogen bond lengths between the water molecules change in a characteristic way, reflecting the strength of the solute-water interaction. These structural effects are also reflected spectroscopically in the shifts of the local mode OH stretch frequencies. When diphenoxyethane is the solute, the water clusters distort more significantly than when bound to benzene. Tricyclophane's structure provides an aromatic-rich binding pocket for the water clusters. The local mode model is used to extract Hamiltonians for individual water molecules. These monomer Hamiltonians divide into groups based on their local H-bonding architecture, allowing for further classification of the wide variety of water environments encountered in this study.

  5. Interaction of water molecules with hexagonal 2D systems. A DFT study

    NASA Astrophysics Data System (ADS)

    Rojas, Ángela; Rey, Rafael

    Over the years water sources have been contaminated with many chemical agents, becoming issues that affect health of the world population. The advances of the nanoscience and nanotechnology in the development new materials constitute an alternative for design molecular filters with great efficiencies and low cost for water treatment and purification. In the nanoscale, the process of filtration or separation of inorganic and organic pollutants from water requires to study interactions of these atoms or molecules with different nano-materials. Specifically, it is necessary to understand the role of these interactions in physical and chemical properties of the nano-materials. In this work, the main interest is to do a theoretical study of interaction between water molecules and 2D graphene-like systems, such as silicene (h-Si) or germanene (h-Ge). Using Density Functional Theory we calculate total energy curves as function of separation between of water molecules and 2D systems. Different spatial configurations of water molecules relative to 2D systems are considered. Structural relaxation effects and changes of electronic charge density also are reported. Universidad Nacional de Colombia.

  6. Auger spectrum of a water molecule after single and double core ionization

    NASA Astrophysics Data System (ADS)

    Inhester, Ludger; Burmeister, Carl F.; Groenhof, Gerrit; Grubmueller, Helmut

    2012-06-01

    The high intensity of Free Electron Lasers (FEL) opens up the possibility to perform single-shot molecule scattering experiments. However, even for small molecules radiation damage induced by absorption of intense x-ray radiation is not yet fully understood. To provide insight into this process, we have studied the dynamics of water molecules in single and double core ionized states by means of electronic transition rate calculations and ab initio molecular dynamics (MD) simulations. From MD trajectories photoionization and Auger transition rates were computed based on electronic continuum wavefunctions obtained by explicit integration of the coupled radial Schr"odinger equations. To account for the nuclear dynamics during the core hole lifetime, the calculated electron emission spectra for different molecular geometries were accumulated according to the obtained time-dependent populations. We find that, in contrast to the single core ionized water molecule, the nuclear dynamics for the double core ionized water molecule during the core hole lifetime leaves a clear fingerprint on the electron emission spectra. In addition, the lifetime of the double core ionized water was found to be significantly shorter than half of the single core hole lifetime.

  7. Femtosecond mid-infrared study of the dynamics of water molecules in water-acetone and water-dimethyl sulfoxide mixtures.

    PubMed

    Lotze, S; Groot, C C M; Vennehaug, C; Bakker, H J

    2015-04-23

    We study the vibrational relaxation dynamics and the reorientation dynamics of HDO molecules in binary water-dimethyl sulfoxide (DMSO) and water-acetone mixtures with polarization-resolved femtosecond mid-infrared spectroscopy. For low solute concentrations we observe a slowing down of the reorientation of part of the water molecules that hydrate the hydrophobic methyl groups of DMSO and acetone. For water-DMSO mixtures the fraction of slowed-down water molecules rises much steeper with solute concentration than for water-acetone mixtures, showing that acetone molecules show significant aggregation already at low concentrations. At high solute concentrations, the vibrational and reorientation dynamics of both water-DMSO and water-acetone mixtures show a clear distinction between the dynamics of water molecules donating hydrogen bonds to other water molecules and the dynamics of water donating a hydrogen bond to the S═O/C═O group of the solute. For water-DMSO mixtures both types of water molecules show a very slow reorientation. The water molecules forming hydrogen bonds to the S═O group reorient with a time constant that decreases from 46 ± 14 ps at XDMSO = 0.33 to 13 ± 2 ps at XDMSO = 0.95. The water molecules forming hydrogen bonds to the C═O group of acetone show a much faster reorientation with a time constant that decreases from 6.1 ± 0.2 ps at Xacet = 0.3 to 2.96 ± 0.05 ps at Xacet = 0.9. The large difference in reorientation time constant of the solute-bound water for DMSO and acetone can be explained from the fact that the hydrogen bond between water and the S═O group of DMSO is much stronger than the hydrogen bond between water and the C═O group of acetone. We attribute the strongly different behavior of water in DMSO-rich and acetone-rich mixtures to their difference in molecular shape.

  8. Molecular mimicry of substrate oxygen atoms by water molecules in the beta-amylase active site.

    PubMed

    Pujadas, G; Palau, J

    2001-08-01

    Soybean beta-amylase (EC 3.2.1.2) has been crystallized both free and complexed with a variety of ligands. Four water molecules in the free-enzyme catalytic cleft form a multihydrogen-bond network with eight strategic residues involved in enzyme-ligand hydrogen bonds. We show here that the positions of these four water molecules are coincident with the positions of four potential oxygen atoms of the ligands within the complex. Some of these waters are displaced from the active site when the ligands bind to the enzyme. How many are displaced depends on the shape of the ligand. This means that when one of the four positions is not occupied by a ligand oxygen atom, the corresponding water remains. We studied the functional/structural role of these four waters and conclude that their presence means that the conformation of the eight side chains is fixed in all situations (free or complexed enzyme) and preserved from unwanted or forbidden conformational changes that could hamper the catalytic mechanism. The water structure at the active pocket of beta-amylase is therefore essential for providing the ligand recognition process with plasticity. It does not affect the protein active-site geometry and preserves the overall hydrogen-bonding network, irrespective of which ligand is bound to the enzyme. We also investigated whether other enzymes showed a similar role for water. Finally, we discuss the potential use of these results for predicting whether water molecules can mimic ligand atoms in the active center.

  9. Effects of water molecules on binding kinetics of peptide receptor on a piezoelectric microcantilever

    NASA Astrophysics Data System (ADS)

    Hui Kim, Sang; Kyoung Yoo, Yong; Chae, Myung-Sic; Yoon Kang, Ji; Song Kim, Tae; Seon Hwang, Kyo; Hoon Lee, Jeong

    2012-12-01

    The use of highly selective reversible peptide receptors is essential for cantilever-based electronic nose systems. Here, we present the effects of water molecules on the binding kinetics of 2,4-dinitrotoluene (DNT) molecules with DNT selective peptide receptors linked with a tri(ethylene glycol)-based (TEG) self-assembled monolayer (SAM) in a gas phase in a piezoelectric microcantilever sensor. We observed 1.5-times faster reaction kinetics in wet conditions compared with dry conditions. In a dissociation step, distinctive differences in the recovery time were observed in wet conditions, which could be attributed to water retention efficiency of TEG-linkers for the conformation of biomolecules.

  10. Coprostanol as a potential tracer of particulate sewage effluent to shelf waters adjacent to the Chesapeake Bay

    NASA Technical Reports Server (NTRS)

    Brown, R. C.; Wade, T. L.

    1981-01-01

    Samples were collected in the Chesapeake Bay entrance and contiguous shelf waters and were subsequently analyzed for particulate coprostanol and cholesterol concentrations. Surface coprostanol concentrations were fairly uniform, with a slight increase with depth. This increase with depth may be due to sewage-associated particulates settling as they leave the Bay, or the resuspension of contaminated sediment. Preliminary findings indicate sewage-associated materials are being transported from the Chesapeake Bay to shelf waters, where they may have a detrimental affect on living marine resources.

  11. An interdisciplinary study of the estuarine and coastal oceanography of Block Island Sound and adjacent New York coastal waters

    NASA Technical Reports Server (NTRS)

    Yost, E. F. (Principal Investigator); Hollman, R.; Alexander, J.; Nuzzi, R.

    1974-01-01

    The author has identified the following significant results. Photo-optical additive color quantitative measurements were made of ERTS-1 reprocessed positives of New York Bight and Block Island Sound. Regression of these data on almost simultaneous ship sample data of water's physical, chemical, biological, and optical properties showed that ERTS bands 5 and 6 can be used to predict the absolute value of the total number of particles and bands 4 and 5 to predict the relative extinction coefficient in New York Bight. Water masses and mixing patterns in Block Island Sound heretofore considered transient were found to be persistent phenomena requiring revision of existing mathematical and hydraulic models.

  12. WATER-ROCK INTERACTIONS INFLUENCING MERCURY FATE AND TRANSPORT FROM AN ABANDONED MINE SITE TO AN ADJACENT AQUATIC ECOSYSTEM

    EPA Science Inventory

    Clear Lake, located 150 km north of San Francisco, is one of the largest fresh water lakes in California and is an important economic resource for the region. Elevated mercury levels in fish in Clear Lake were identified in the late 1970s, resulting in a fish consumption advisor...

  13. 33 CFR 334.420 - Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) Bombing and rocket firing area in Pamlico Sound in vicinity of Brant Island—(1) The area. The waters.... Upon being so warned vessels working in the area shall leave the area immediately. (b) Bombing, rocket... regulations. (i) The area described in paragraph (b)(1) of this section will be used as bombing, rocket...

  14. 33 CFR 334.420 - Pamlico Sound and adjacent waters, N.C.; danger zones for Marine Corps operations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Bombing and rocket firing area in Pamlico Sound in vicinity of Brant Island—(1) The area. The waters.... Upon being so warned vessels working in the area shall leave the area immediately. (b) Bombing, rocket... regulations. (i) The area described in paragraph (b)(1) of this section will be used as bombing, rocket...

  15. Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic Waters: A Guide to Their Identification.

    ERIC Educational Resources Information Center

    Leatherwood, Stephen; And Others

    This field guide is designed to permit observers to identify the cetaceans (whales, dolphins, and porpoises) they see in the waters of the eastern North Pacific, including the Gulf of California, Hawaii, and the western Arctic of North America. The animals described are grouped not by scientific relationships but by similarities in appearance in…

  16. Water, UV shielding, and Organic Molecules in the Terrestrial Planet Region of Disks

    NASA Astrophysics Data System (ADS)

    Najita, Joan; Carr, John

    2015-08-01

    Water vapor is abundant in the inner few AU of protoplanetary disks, as shown by the common detection of mid-infrared emission lines of warm water in T Tauri disk atmospheres. Simple organic molecules are also abundant. The properties of the water and organic molecule emission (column densities and abundances) hint at an active disk chemistry and the synthesis of complex organic molecules. Because T Tauri disks have experienced significant grain growth and settling, the water in the disk atmosphere is expected to be a significant UV opacity source. Recent models of disk atmospheres show that the absorption of stellar FUV photons by water and other molecules not only heats the disk atmosphere but also shields the disk midplane from UV radiation. The properties of the molecular layers synthesized in the models are in good agreement with the observed infrared molecular emission from T Tauri stars. In addition to describing these model results, we will present direct observational evidence for the photodissociation of water and its role in shielding T Tauri disks. Detailed study of the mid-infrared OH emission spectrum reveals the signature of a photochemical origin for the OH, i.e., OH production through photodissociation of water by FUV photons at 1150-1400 A, most likely dominated by Lyman alpha. The nearly ubiquitous presence of rotationally hot OH emission in classical T Tauri stars implies that photodissociation of water is common in the terrestrial planet region of the disk. The resulting UV shielding by water could be important in facilitating a rich organic chemistry in the disk midplane.

  17. Ground-water quality and discharge to Chincoteague and Sinepuxent Bays adjacent to Assateague Island National Seashore, Maryland

    USGS Publications Warehouse

    Dillow, Jonathan J.A.; Banks, William S.L.; Smigaj, Michael J.

    2002-01-01

    The U.S. Geological Survey, in cooperation with the Maryland Department of the Environment and the Wisconsin State Laboratory of Hygiene, conducted a study to characterize the occurrence and distribution of viral contamination in small (withdrawing less than 10,000 gallons per day) public water-supply wells screened in the shallow aquifer in the Piedmont Physiographic Province in Baltimore and Harford Counties, Maryland. Two hundred sixty-three small public water-supply wells were in operation in these counties during the spring of 2000. Ninety-one of these sites were selected for sampling using a methodology that distributed the samples evenly over the population and the spatial extent of the study area. Each site, and its potential susceptibility to microbiological contamination, was evaluated with regard to hole depth, casing interval, and open interval. Each site was evaluated using characteristics such as on-site geology and on-site land use.Samples were collected by pumping between 200 and 400 gallons of untreated well water through an electropositive cartridge filter. Water concentrates were subjected to cell-culture assay for the detection of culturable viruses and reverse-transcription polymerase chain reaction/gene probe assays to detect viral ribonucleic acid; grab samples were analyzed for somatic and male-specific coliphages, Bacteroides fragilis, Clostridium perfringens, enterococci, Escherichia coli, total coliforms, total oxidized nitrogen, nitrite, organic nitrogen, total phosphate, ortho-phosphate, calcium, magnesium, sodium, potas-sium, chloride, sulfate, iron, acid-neutralizing capacity, pH, specific conductance, temperature, and dissolved oxygen.One sample tested positive for the presence of the ribonucleic acid of rotavirus through poly-merase chain-reaction analysis. Twenty-nine per-cent of the samples (26 of 90) had bacterial con-tamination. About 7 percent of the samples (6 of 90) were contaminated with either male-specific coliphage

  18. Local lateral environment of the molecules at the surface of DMSO-water mixtures

    NASA Astrophysics Data System (ADS)

    Fábián, Balázs; Idrissi, Abdenacer; Marekha, Bogdan; Jedlovszky, Pál

    2016-10-01

    Molecular dynamics simulations of the liquid-vapour interface of dimethyl sulphoxide (DMSO)-water mixtures of 11 different compositions, including two neat systems are performed on the canonical (N, V, T) ensemble at 298 K. The molecules constituting the surface layer of these systems are selected by means of the identification of the truly interfacial molecules (ITIM) method, and their local lateral environment at the liquid surface is investigated by performing Voronoi analysis. The obtained results reveal that both molecules prefer to be in a mixed local environment, consisting of both kinds of molecules, at the liquid surface, and this preference is even stronger here than in the bulk liquid phase. Neat-like patches, in which a molecule is surrounded by like neighbours, are not found. However, vacancies that are surrounded solely by water molecules are observed at the liquid surface. Our results show that strongly hydrogen bonded DMSO·H2O complexes, known to exist in the bulk phase of these mixtures, are absent from the liquid surface.

  19. Intracomplex {pi}-{pi} stacking interaction between adjacent phenanthroline molecules in complexes with rare-earth nitrates: Crystal and molecular structures of bis(1,10-Phenanthroline)trinitratoytterbium and bis(1,10-Phenanthroline)trinitratolanthanum

    SciTech Connect

    Sadikov, G. G. Antsyshkina, A. S.; Rodnikova, M. N.; Solonina, I. A.

    2009-01-15

    Crystals of the compounds Yb(NO{sub 3}){sub 3}(Phen){sub 2} and La(NO{sub 3}){sub 3}(Phen){sub 2} (Phen = 1,10-phenanthroline) are investigated using X-ray diffraction. It is established that there exist two different crystalline modifications: the main modification (phase 1) is characteristic of all members of the isostructural series, and the second modification (phase 2) is observed only for the Eu, Er, and Yb elements. It is assumed that the stability and universality of main phase 1 are associated with the occurrence of the nonbonded {pi}-{pi} stacking interactions between the adjacent phenanthroline ligands in the complexes. The indication of the interactions is a distortion of the planar shape of the Phen molecule (the folding of the metallocycle along the N-N line with a folding angle of 11{sup o}-13{sup o} and its 'boomerang' distortion). The assumption regarding the {pi}-{pi} stacking interaction is very consistent with the shape of the ellipsoids of atomic thermal vibrations, as well as with the data obtained from thermography and IR spectroscopy. An analysis of the structures of a number of rare-earth compounds has demonstrated that the intracomplex {pi}-{pi} stacking interactions directly contribute to the formation of supramolecular associates in the crystals, such as molecular dimers, supramolecules, chain and layered ensembles, and framework systems.

  20. Proton transfer in hydrogen-bonded network of phenol molecules: intracluster formation of water.

    PubMed

    Lengyel, Jozef; Gorejová, Radka; Herman, Zdeněk; Fárník, Michal

    2013-11-07

    Electron ionization and time-of-flight mass spectrometry was used to investigate the phenol clusters (PhOH)n of different size from single molecule to large clusters: in coexpansion with He, the dimers n = 2 are mostly generated; in Ar, large species of n ≥ 10 also occur. Besides [(PhOH)n](+•) cluster ion series, hydrated phenol cluster ions [(PhOH)n·xH2O](+•) with up to x = 3 water molecules and dehydrated phenol clusters [(PhOH)n-H2O](+•) were observed. The hydrated phenol series exhibits minima and maxima that are interpreted as evidence for proton transfer between the hydrogen bonded cluster ions of cyclic structures. The proton transfer leads to a water generation within the clusters, and subsequent elimination of the diphenyl ether molecule(s) from the cluster yields the hydrated phenol cluster ions. Alternatively, a water molecule release yields a series of dehydrated phenols, among which the diphenyl ether ion [PhOPh](+•) (n = 2) constitutes the maximum.

  1. DFTr optimization and DFTr-MD studies of glucose, ten explicit water molecules enclosed by an implicit solvent, COSMO

    Technology Transfer Automated Retrieval System (TEKTRAN)

    DFTr optimization studies are carried out on alpha/beta-glucose surrounded by ten explicit water molecules and the glucose/water super-molecule completely enclosed by an implicit solvation model, COSMO. Twenty one starting configurations of the explicit waters were first optimized empirically with t...

  2. Study of the betulin molecule in a water environment; ab initio and molecular simulation calculations.

    PubMed

    Pospíšil, Miroslav; Kovář, Petr; Vácha, Robert; Svoboda, Michal

    2012-01-01

    Ab initio and molecular simulation methods were used in calculations of the neutral individual betulin molecule, and molecular simulations were used to optimize the betulin molecule immersed in various amounts of water. Individual betulin was optimized in different force fields to find the one exhibiting best agreement with ab initio calculations obtained in the Gaussian03 program. Dihedral torsions of active groups of betulin were determined for both procedures, and related calculated structures were compared successfully. The selected force field was used for subsequent optimization of betulin in a water environment, and a conformational search was performed using quench molecular dynamics. The total energies of betulin and its interactions in water bulk were calculated, and the influence of water on betulin structure was investigated.

  3. Clustering of water molecules in ultramicroporous carbon: In-situ small-angle neutron scattering

    DOE PAGES

    Bahadur, Jitendra; Contescu, Cristian I.; Rai, Durgesh K.; ...

    2016-10-19

    The adsorption of water is central to most of the applications of microporous carbon as adsorbent material. We report early kinetics of water adsorption in the microporous carbon using in-situ small-angle neutron scattering. It is observed that adsorption of water occurs via cluster formation of molecules. Interestingly, the cluster size remains constant throughout the adsorption process whereas number density of clusters increases with time. The role of surface chemistry of microporous carbon on the early kinetics of adsorption process was also investigated. Lastly, the present study provides direct experimental evidence for cluster assisted adsorption of water molecules in microporous carbonmore » (Do-Do model).« less

  4. Molecular Water Lilies: Orienting Single Molecules in a Polymer Film by Solvent Vapor Annealing.

    PubMed

    Würsch, Dominik; Hofmann, Felix J; Eder, Theresa; Aggarwal, A Vikas; Idelson, Alissa; Höger, Sigurd; Lupton, John M; Vogelsang, Jan

    2016-11-17

    The microscopic orientation and position of photoactive molecules is crucial to the operation of optoelectronic devices such as OLEDs and solar cells. Here, we introduce a shape-persistent macrocyclic molecule as an excellent fluorescent probe to simply measure (i) its orientation by rotating the excitation polarization and recording the strength of modulation in photoluminescence (PL) and (ii) its position in a film by analyzing the overall PL brightness at the molecular level. The unique shape, the absorption and the fluorescence properties of this probe yield information on molecular orientation and position. We control orientation and positioning of the probe in a polymer film by solvent vapor annealing (SVA). During the SVA process the molecules accumulate at the polymer/air interface, where they adopt a flat orientation, much like water lilies on the surface of a pond. The results are potentially significant for OLED fabrication and single-molecule spectroscopy (SMS) in general.

  5. The influence of climate cycles on the water regime and carbonate profile in chernozems of Central European Russia and adjacent territories

    NASA Astrophysics Data System (ADS)

    Bazykina, G. S.; Ovechkin, S. V.

    2016-04-01

    The influence of long-term "dry" and "wet" climatic cycles on the water regime, hydrological parameters, and carbonate profiles of chernozems in Central European Russia and adjacent territories was studied. The hydrological and carbonate profiles were found to change during the wet cycle. However, the upper part of the hydrological profile is basically unchanging, whereas in its lower part, the number of hydrological horizons and contrast in their moistening decrease in the forest-steppe chernozems and increase in the steppe chernozems. The frequency of through wetting of chernozems increases during the wet cycles. The vertical lithological heterogeneity of the parent material affects the soil moisture status. In the wet climatic cycle, the moisture content above the lithological contact increases resulting in the development of the features of soil hydromorphism. In the carbonate profile, the character of pedofeatures is changing: some carbonate neoformations disappear, while the other ones develop. Possible variations of the periodically percolative water regime were revealed in chernozems. The classification of water regime proposed by A.A. Rode may be updated based on the data obtained during the dry climatic cycle. Rode's hypothesis about cyclic variations in the soil water regime is confirmed.

  6. Turnover and release of P-, N-, Si-nutrients in the Mexicali Valley (Mexico): interactions between the lower Colorado River and adjacent ground- and surface water systems.

    PubMed

    Orozco-Durán, A; Daesslé, L W; Camacho-Ibar, V F; Ortiz-Campos, E; Barth, J A C

    2015-04-15

    A study on dissolved nitrate, ammonium, phosphate and silicate concentrations was carried out in various water compartments (rivers, drains, channels, springs, wetland, groundwater, tidal floodplains and ocean water) in the Mexicali Valley and the Colorado River delta between 2012 and 2013, to assess modern potential nutrient sources into the marine system after river damming. While nitrate and silicate appear to have a significant input into the coastal ocean, phosphate is rapidly transformed into a particulate phase. Nitrate is, in general, rapidly bio-consumed in the surface waters rich in micro algae, but its excess (up to 2.02 mg L(-1) of N from NO3 in winter) in the Santa Clara Wetland represents a potential average annual source to the coast of 59.4×10(3)kg N-NO3. Despite such localized inputs, continuous regional groundwater flow does not appear to be a source of nitrate to the estuary and coastal ocean. Silicate is associated with groundwaters that are also geothermally influenced. A silicate receiving agricultural drain adjacent to the tidal floodplain had maximum silicate concentrations of 16.1 mg L(-1) Si-SiO2. Seepage of drain water and/or mixing with seawater during high spring tides represents a potential source of dissolved silicate and nitrate into the Gulf of California.

  7. The fish and prawn communities of a Malaysian coastal mangrove system, with comparisons to adjacent mud flats and inshore waters

    NASA Astrophysics Data System (ADS)

    Chong, V. C.; Sasekumar, A.; Leh, M. U. C.; D'Cruz, R.

    1990-11-01

    The fish and prawn communities of four coastal habitats in Selangor, Malaysia: (1) coastal mangrove swamps; (2) mud flats, including subtidal regions; (3) near inshore waters; and (4) far inshore waters, were examined with respect to species composition, abundance, diversity, similarity and sexual maturity. The number of fish species sampled for these habitats were 119, 70, 58 and 92 species respectively. For prawns, the number of species were 9, 16, 8 and 14 respectively. The mangrove community comprised 63-99% and 100% juvenile fish and prawn respectively. Despite a high species richness, it was low in fish species diversity due to the dominance (70%) of six species of fish of low economic value. In contrast, the prawn community was poor in species, and was dominated by three Penaeus spp. of high economic value. The intertidal mudflat community is largely transient and comprised mainly of species from both the mangrove and subtidal habitats. Fifty-six per cent of the fish population and 62·6% of the prawn population were juveniles. Many of the inshore fish and prawn species were also common species found in mangrove and mudflat habitats. Similarity coefficients indicate that the inshore fish and prawn communities are more similar to those of mud flats than mangroves. However, maturity studies indicate that only five species of fish are true migrants, that the majority of the fish species (juveniles and adults) are ubiquitous with a distribution that extends several nautical miles offshore. Results of this study indicate that tropical coastal mangroves function more importantly as feeding grounds than as nursery grounds for juveniles of commercially important fish species. Mangroves and mud flats are utilized during flood tides by many periodic foragers from the inshore waters. However, this study confirms that coastal mangroves and mud flats are important nursery areas for commercially important prawn species.

  8. An interpretation of the enhancement of the water dipole moment due to the presence of other water molecules.

    PubMed

    Kemp, Daniel D; Gordon, Mark S

    2008-06-05

    The dipole moment of the gas phase water monomer is 1.85 D. When solvated in bulk water, the dipole moment of an individual water molecule is observed to be enhanced to the much larger value of 2.9 +/- 0.6 D. To understand the origin of this dipole moment enhancement, the effective fragment potential (EFP) method is used to solvate an ab initio water molecule to predict the dipole moments for various cluster sizes. The dipole moment as a function of cluster size, nH 2O, is investigated [for n = 6-20 (even n), 26, 32, 41, and 50]. Localized charge distributions are used in conjunction with localized molecular orbitals to interpret the dipole moment enhancement. These calculations suggest that the enhancement of the dipole moment originates from the decrease of the angle between the dipole vectors of the lone pairs on oxygen as the number of hydrogen bonds to that oxygen increases. Thus, the decreased angle, and the consequent increase in water dipole moment, is most likely to occur in environments with a larger number of hydrogen bonds, such as the center of a cluster of water molecules.

  9. In vivo diffusion MRS investigation of non-water molecules in biological tissues.

    PubMed

    Cao, Peng; Wu, Ed X

    2017-03-01

    Diffusion MRS of non-water molecules offers great potential in directly revealing various tissue microstructures and physiology at both cellular and subcellular levels. In brain, (1) H diffusion MRS has been demonstrated as a new tool for probing normal tissue microstructures and their pathological changes. In skeletal muscle, (1) H diffusion MRS could characterize slow and restricted intramyocellular lipid diffusion, providing a sensitive marker for metabolic alterations, while (31) P diffusion MRS can measure ATP and PCr diffusion, which may reflect the capacity of cellular energy transport, complementing the information from frequently used (31) P MRS in muscle. In intervertebral disk, (1) H diffusion MRS can directly monitor extracellular matrix integrity by quantifying the mobility of macromolecules such as proteoglycans and collagens. In tumor tissue, (13) C diffusion MRS could probe intracellular glycolytic metabolism, while (1) H diffusion MRS may separate the spectrally overlapped lactate and lipid resonances. In this review, recent diffusion MRS studies of these biologically relevant non-water molecules under normal and diseased conditions will be presented. Technical considerations for diffusion MRS experiments will be discussed. With advances in MRI hardware and diffusion methodology, diffusion MRS of non-water molecules is expected to provide increasingly valuable and biologically specific information on tissue microstructures and physiology, complementing the traditional diffusion MRI of small and ubiquitous water molecules. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Contribution of water molecules in the spontaneous release of protein by graphene sheets.

    PubMed

    Liang, Li-Jun; Wang, Qi; Wu, Tao; Sun, Tian-Yang; Kang, Yu

    2013-09-16

    Applications of graphene sheets in the fields of biosensors and biomedical devices are limited by the aqueous solubility of graphene. Consequently, understanding the role of water molecules in the aggregation or dispersion of graphene in aqueous solution with a biomolecule is of vital importance to its application. Herein, protein is spontaneously released by the layer-to-layer aggregation of two single-layer graphene sheets due to van der Waals force between the sheets. The properties of water molecules, including density and dynamics, are discussed in detail. The dynamic behavior of aggregation of graphene sheets is triggered by the dynamics of water molecules. To stabilize dispersed graphene sheets in aqueous solution, the density of water molecules between the graphene sheets should be larger than 0.83 g cm(-3), and graphene modified by hydroxyl groups could be a good choice. The stability of a model protein on the graphene sheet is studied to investigate the biological compatibility of graphene sheets. To be a material with good biocompatibility, graphene should be functionalized by hydrophilic groups. The results presented herein could be helpful in the research and application of graphene sheets in the fields of biomaterials, biosensors, and biomedical devices.

  11. Thermodynamics of hydrogen bond patterns in supramolecular assemblies of water molecules.

    PubMed

    Henry, Marc

    2002-07-02

    The PACHA (Partial Atomic Charges and Hardnesses Analysis) formalism is applied to various supramolecular assemblies of water molecules. After a detailed study of all available crystal structures for ice polymorphs, we shown that the hydrogen bond strength is roughly constant below 1 GPa and considerably weakened above that value. New hydrogen bond patterns are proposed for ice IV, V, and VI after (EB) (electrostatic balance) minimization. For other polymorphs, there is an almost perfect coincidence between experimental and predicted hydrogen bond patterns. The evolution of hydrogen bond energy as a function of molecular geometry in water clusters with up to 280 water molecules and in large supramolecular compounds is quantitatively described. Intermolecular hydrogen bonds are found to lie between -9 and -32 kJ mol-1, the stronger interaction occurs within the spherical fully disordered water droplet buried at the heart of Müller's superfullerene keplerate. The weakest one occurs in a chiral molecular snub cube built from six calix[4]resorcinarene and eight water molecules. Intramolecular hydrogen bonds are found in the range -10-100 kJ mol-1 and can thus be considerably stronger than intermolecular bonds. Finally, through the investigation of a clathrate type I compound, it was possible to obtain a deep insight of the host-guest interactions and self-assembly rules of water cages in these materials.

  12. Review of samples of sediment, tailings, and waters adjacent to the Cactus Queen gold mine, Kern County, California

    USGS Publications Warehouse

    Rytuba, James J.; Kim, Christopher S.; Goldstein, Daniel N.

    2011-01-01

    The Cactus Queen Mine is located in the western Mojave Desert in Kern County, California. The Cactus Queen gold-silver (Au-Ag) deposit is similar to other Au-Ag deposits hosted in Miocene volcanic rocks that consist of silicic domes and associated flows, pyroclastic rocks, and subvolcanic intrusions. The volcanic rocks were emplaced onto a basement of Mesozoic silicic intrusive rocks. A part of the Cactus Queen Mine is located on Federal land managed by the U.S. Bureau of Land Management (BLM). Staff from the BLM initially sampled the mine area and documented elevated concentrations of arsenic (As) in tailings and sediment. BLM then requested that the U.S. Geological Survey (USGS), in collaboration with Chapman University, measure and characterize As and other geochemical constituents in sediment, tailings, and waters on the part of the mine on Federal lands. This report is made in response to the request by the BLM, the lead agency mandated to conduct a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) - Removal Site Investigation (RSI). The RSI applies to the potential removal of As-contaminated mine waste from the Cactus Queen Mine as a means of reducing As release and exposure to humans and biota. This report summarizes data obtained from field sampling of sediments, mine tailings, and surface waters at the Cactus Queen Mine on January 27, 2008. Our results provide a preliminary assessment of the sources of As and associated chemical constituents that could potentially impact humans and biota.

  13. Conserved water molecules in family 1 glycosidases: a DXMS and molecular dynamics study.

    PubMed

    Teze, David; Hendrickx, Johann; Dion, Michel; Tellier, Charles; Woods, Virgil L; Tran, Vinh; Sanejouand, Yves-Henri

    2013-08-27

    By taking advantage of the wealth of structural data available for family 1 glycoside hydrolases, a study of the conservation of internal water molecules found in this ubiquitous family of enzymes was undertaken. Strikingly, seven water molecules are observed in more than 90% of the known structures. To gain insight into their possible function, the water dynamics inside Thermus thermophilus β-glycosidase was probed using deuterium exchange mass spectroscopy, allowing the pinpointing of peptide L117-A125, which exchanges most of its amide hydrogens quickly in spite of the fact that it is for the most part buried in the crystal structure. To help interpret this result, a molecular dynamics simulation was performed whose analysis suggests that two water channels are involved in the process. The longest one (∼16 Å) extends between the protein surface and W120, whose side chain interacts with E164 (the acid-base residue involved in the catalytic mechanism), whereas the other channel allows for the exchange with the bulk of the highly conserved water molecules belonging to the hydration shell of D121, a deeply buried residue. Our simulation also shows that another chain of highly conserved water molecules, going from the protein surface to the bottom of the active site cleft close to the nucleophile residue involved in the catalytic mechanism, is able to exchange with the bulk on the nanosecond time scale. It is tempting to speculate that at least one of these three water channels could be involved in the function of family 1 glycoside hydrolases.

  14. Sewage effluent clean-up reduces phosphorus but not phytoplankton in lowland chalk stream (River Kennet, UK) impacted by water mixing from adjacent canal.

    PubMed

    Neal, Colin; Martin, Ellie; Neal, Margaret; Hallett, John; Wickham, Heather D; Harman, Sarah A; Armstrong, Linda K; Bowes, Mike J; Wade, Andrew J; Keay, David

    2010-10-15

    Information is provided on phosphorus in the River Kennet and the adjacent Kennet and Avon Canal in southern England to assess their interactions and the changes following phosphorus reductions in sewage treatment work (STW) effluent inputs. A step reduction in soluble reactive phosphorus (SRP) concentration within the effluent (5 to 13 fold) was observed from several STWs discharging to the river in the mid-2000s. This translated to over halving of SRP concentrations within the lower Kennet. Lower Kennet SRP concentrations change from being highest under base-flow to highest under storm-flow conditions. This represented a major shift from direct effluent inputs to a within-catchment source dominated system characteristic of the upper part to the catchment. Average SRP concentrations in the lower Kennet reduced over time towards the target for good water quality. Critically, there was no corresponding reduction in chlorophyll-a concentration, the waters remaining eutrophic when set against standards for lakes. Following the up gradient input of the main water and SRP source (Wilton Water), SRP concentrations in the canal reduced down gradient to below detection limits at times near its junction with the Kennet downstream. However, chlorophyll concentrations in the canal were in an order of magnitude higher than in the river. This probably resulted from long water residence times and higher temperatures promoting progressive algal and suspended sediment generations that consumed SRP. The canal acted as a point source for sediment, algae and total phosphorus to the river especially during the summer months when boat traffic disturbed the canal's bottom sediments and the locks were being regularly opened. The short-term dynamics of this transfer was complex. For the canal and the supply source at Wilton Water, conditions remained hypertrophic when set against standards for lakes even when SRP concentrations were extremely low.

  15. Hydrogen bonding changes of internal water molecules in rhodopsin during metarhodopsin I and metarhodopsin II formation.

    PubMed Central

    Rath, P; Delange, F; Degrip, W J; Rothschild, K J

    1998-01-01

    Rhodopsin is a 7-helix, integral membrane protein found in the rod outer segments, which serves as the light receptor in vision. Light absorption by the retinylidene chromophore of rhodopsin triggers an 11-cis-->all-trans isomerization, followed by a series of protein conformational changes, which culminate in the binding and activation of the G-protein transducin by the metarhodopsin II (Meta II) intermediate. Fourier transform IR difference spectroscopy has been used to investigate the structural changes that water, as well as other OH- and NH-containing groups, undergo during the formation of the metarhodopsin I (Meta I) and Meta II intermediates. Bands associated with the OH stretch modes of water are identified by characteristic downshifts upon substitution of H2(18)O for H2O. Compared with earlier work, several negative bands associated with water molecules in unphotolysed rhodopsin were detected, which shift to lower frequencies upon formation of the Meta I and Meta II intermediates. These data indicate that at least one water molecule undergoes an increase in hydrogen bonding upon formation of the Meta I intermediate, while at least one other increases its hydrogen bonding during Meta II formation. Amino acid residue Asp-83, which undergoes a change in its hydrogen bonding during Meta II formation, does not appear to interact with any of the structurally active water molecules. Several NH and/or OH groups, which are inaccessible to hydrogen/deuterium exchange, also undergo alterations during Meta I and Meta II formation. PMID:9445403

  16. Neuroscience of water molecules: a salute to professor Linus Carl Pauling.

    PubMed

    Nakada, Tsutomu

    2009-04-01

    More than 35 years ago double Nobel laureate Linus Carl Pauling published a powerful model of the molecular mechanism of general anesthesia, generally referred to as the hydrate-microcrystal (aqueous-phase) theory. This hypothesis, based on the molecular behavior of water molecules, did not receive serious attention during Pauling's life time, when scientific tools for examining complex systems such as the brain were still in their infancy. The situation has since drastically changed, and, now, in the twenty first century, many scientific tools are available for examining different types of complex systems. The discovery of aquaporin-4, a subtype of water channel abundantly expressed in glial systems, further highlighted the concept that the dynamics of water molecules in the cerebral cortex play an important role in important physiological brain functions including consciousness and information processing.

  17. Rotational excitation of water by hydrogen molecules: comparison of results from classical and quantum mechanics.

    PubMed

    Faure, Alexandre; Wiesenfeld, Laurent; Wernli, Michael; Valiron, Pierre

    2006-06-07

    Quasiclassical trajectory calculations are carried out for rotational excitation of water by hydrogen molecules. State-to-state rate coefficients are determined at 100 K and are compared to available quantum results. A good agreement between classical and quantum rates is observed for downward transitions, with an average accuracy of classical results better than a factor of 2. It is thus found that the ambiguities described by Faure and Wiesenfeld [J. Chem. Phys. 121, 6771 (2004)] can be solved in the particular case of waterlike asymmetric-top molecules.

  18. Monte Carlo simulation of several biologically relevant molecules and zwitterions in water

    NASA Astrophysics Data System (ADS)

    Patuwo, Michael Y.; Bettens, Ryan P. A.

    2012-02-01

    In this work, we study the hydration free energies of butane, zwitterionic alanine, valine, serine, threonine, and asparagine, and two neuraminidase inhibitors by means of Monte Carlo (MC) simulation. The solute molecule, represented in the form of distributed multipoles and modified 6-12 potential, was varied from a non-interacting 'ghost' molecule to its full potential functions in TIP4P water. Intermediate systems with soft-core solute-solvent interaction potentials are simulated separately and then subjected to Bennett's Acceptance ratio (BAR) for the free energy calculation. Hydration shells surrounding the solute particles were used to assess the quality of potential functions.

  19. Evaluation of cracking in feedwater piping adjacent to the steam generators in Nine Pressurized Water Reactor Plants

    SciTech Connect

    Goldberg, A.; Streit, R.D.; Scott, R.G.

    1980-06-25

    Cracking in ASTM A106-B and A106-C feedwater piping was detected near the inlet to the steam generators in a number of pressurized water reactor plants. We received sections with cracks from nine of the plants with the objective of identifying the cracking mechanism and assessing various factors that might contribute to this cracking. Variations were observed in piping surface irregularities, corrosion-product, pit, and crack morphology, surface elmental and crystal structure analyses, and steel microstructures and mechanical properties. However, with but two exceptions, namely, arrest bands and major surface irregularities, we were unable to relate the extent of cracking to any of these factors. Tensile and fracture toughness (J/sub Ic/ and tearing modulus) properties were measured over a range of temperatures and strain rates. No unusual properties or microstructures were observed that could be related to the cracking problem. All crack surfaces contained thick oxide deposits and showed evidence of cyclic events in the form of arrest bands. Transmission electron microscopy revealed fatigue striations on replicas of cleaned crack surfaces from one plant and possibly from three others. Calculations based on the observed striation spacings gave a value of ..delta..sigma = 150 MPa (22 ksi) for one of the major cracks. The direction of crack propagation was invariably related to the piping surface and not to the piping axis. These two factors are consistent with the proposed concept of thermally induced, cyclic, tensile surface stresses. Although surface irregularities and corrosion pits were sources for crack initiation and corrosion may have contributed to crack propagation, it is proposed that the overriding factor in the cracking problem is the presence of unforeseen cyclic loads.

  20. Distribution and relative abundance of humpback whales in relation to environmental variables in coastal British Columbia and adjacent waters

    NASA Astrophysics Data System (ADS)

    Dalla Rosa, Luciano; Ford, John K. B.; Trites, Andrew W.

    2012-03-01

    Humpback whales are common in feeding areas off British Columbia (BC) from spring to fall, and are widely distributed along the coast. Climate change and the increase in population size of North Pacific humpback whales may lead to increased anthropogenic impact and require a better understanding of species-habitat relationships. We investigated the distribution and relative abundance of humpback whales in relation to environmental variables and processes in BC waters using GIS and generalized additive models (GAMs). Six non-systematic cetacean surveys were conducted between 2004 and 2006. Whale encounter rates and environmental variables (oceanographic and remote sensing data) were recorded along transects divided into 4 km segments. A combined 3-year model and individual year models (two surveys each) were fitted with the mgcv R package. Model selection was based primarily on GCV scores. The explained deviance of our models ranged from 39% for the 3-year model to 76% for the 2004 model. Humpback whales were strongly associated with latitude and bathymetric features, including depth, slope and distance to the 100-m isobath. Distance to sea-surface-temperature fronts and salinity (climatology) were also constantly selected by the models. The shapes of smooth functions estimated for variables based on chlorophyll concentration or net primary productivity with different temporal resolutions and time lags were not consistent, even though higher numbers of whales seemed to be associated with higher primary productivity for some models. These and other selected explanatory variables may reflect areas of higher biological productivity that favor top predators. Our study confirms the presence of at least three important regions for humpback whales along the BC coast: south Dixon Entrance, middle and southwestern Hecate Strait and the area between La Perouse Bank and the southern edge of Juan de Fuca Canyon.

  1. Modeling the Physical and Biochemical Influence of Ocean Thermal Energy Conversion Plant Discharges into their Adjacent Waters

    SciTech Connect

    PAT GRANDELLI, P.E.; GREG ROCHELEAU; JOHN HAMRICK, Ph.D.; MATT CHURCH, Ph.D.; BRIAN POWELL, Ph.D.

    2012-09-29

    This paper describes the modeling work by Makai Ocean Engineering, Inc. to simulate the biochemical effects of of the nutrient-enhanced seawater plumes that are discharged by one or several 100 megawatt OTEC plants. The modeling is needed to properly design OTEC plants that can operate sustainably with acceptably low biological impact. In order to quantify the effect of discharge configuration and phytoplankton response, Makai Ocean Engineering implemented a biological and physical model for the waters surrounding O`ahu, Hawai`i, using the EPA-approved Environmental Fluid Dynamics Code (EFDC). Each EFDC grid cell was approximately 1 square kilometer by 20 meters deep, and used a time step of three hours. The biological model was set up to simulate the biochemical response for three classes of organisms: Picoplankton (< 2 um) such as prochlorococccus, nanoplankton (2-20 um), and microplankton (> 20 um) e.g., diatoms. The dynamic biological phytoplankton model was calibrated using chemical and biological data collected for the Hawaii Ocean Time Series (HOTS) project. Peer review of the biological modeling was performed. The physical oceanography model uses boundary conditions from a surrounding Hawai'i Regional Ocean Model, (ROM) operated by the University of Hawai`i and the National Atmospheric and Oceanic Administration. The ROM provided tides, basin scale circulation, mesoscale variability, and atmospheric forcing into the edges of the EFDC computational domain. This model is the most accurate and sophisticated Hawai'ian Regional Ocean Model presently available, assimilating real-time oceanographic observations, as well as model calibration based upon temperature, current and salinity data collected during 2010 near the simulated OTEC site. The ROM program manager peer-reviewed Makai's implementation of the ROM output into our EFDC model. The supporting oceanographic data was collected for a Naval Facilities Engineering Command / Makai project. Results: The model

  2. Particulate nitrogen and phosphorus in the East China Sea and its adjacent Kuroshio waters and evaluation of budgets for the East China Sea Shelf

    NASA Astrophysics Data System (ADS)

    Zuo, Jiulong; Song, Jinming; Yuan, Huamao; Li, Xuegang; Li, Ning; Duan, Liqin

    2016-12-01

    Nitrogen (N) and phosphorus (P) in suspended particles are important to the cycles of N and P in marine ecosystem. Suspended particles were collected from the East China Sea (ECS) and its adjacent Kuroshio waters to investigate the composing and distribution characteristics of particulate inorganic and organic nitrogen and phosphorus (PIN, PIP, PON and POP, respectively). The particulate N and P concentrations were fairly low in the Kuroshio water but much higher in the ECS water, especially in nearshore waters. PON and PIP were the dominant forms of particulate N and P, with an exception that POP was the major form of particulate P in the Kuroshio upper water. The regime of particulate N and P in the ECS was strongly influenced by riverine input, oceanic input, ocean current and photosynthesis. Among them, PON and POP were mainly from biogenic source, while PIN and PIP were originated from biogenic and external sources. And sedimentation, remineralization and resuspension were important influencing factors for the vertical distributions of particulate N and P. The budgets of particulate N and P for the ECS Shelf during rainy season (May-October) were also evaluated. The total particulate N and P (TPN and TPP) fluxes from oceanic input are respectively 10.99 and 2.49 times of those from riverine input. And oceanic input contains more POP, which is liable to be decomposed into phosphate, than riverine input. Furthermore, particulate nutrients fluxes from photosynthesis are the overriding source of total influxes for the ECS Shelf, accounting for 90.93% of TPN and 89.37% of TPP influxes. As for the photosynthetic fixed N and P, only 6.17% and 7.60% of them can reach the seafloor, while up to 87.73% and 60.06% of them are likely to be remineralized. The POP-rich oceanic input and the intensive photosynthesis and remineralization processes play important roles in the biogeochemical cycles of N and P in the ECS.

  3. Distribution and ecological risk assessment of polycyclic aromatic hydrocarbons in water, suspended particulate matter and sediment from Daliao River estuary and the adjacent area, China.

    PubMed

    Zheng, Binghui; Wang, Liping; Lei, Kun; Nan, Bingxu

    2016-04-01

    Polycyclic aromatic hydrocarbons (PAHs) contamination was investigated in concurrently sampled surface water, suspended particulate matter (SPM) and sediment of Daliao River estuary and the adjacent area, China. The total concentrations of PAHs ranged from 71.12 to 4255.43 ng/L in water, from 1969.95 to 11612.21 ng/L in SPM, and from 374.84 to 11588.85 ng/g dry weight (dw) in sediment. Although the 2-3 ring PAHs were main PAH congeners in water and SPM, the 4-6 ring PAHs were also detected and their distribution was site-specific, indicating a very recent PAHs input around the area since they were hydrophobic. The PAHs pollution was identified as mixed combustion and petroleum sources. Based on species sensitivity distribution (SSD), the ecological risk in SPM from 82% stations was found to be higher obviously than that in water. The risk in water was basically ranked as medium, while the risk in SPM was ranked as high. Analysis with sediment quality guidelines (SQGs) indicated that negative eco-risk occasionally occurred in about 50% stations, while negative eco-risk frequently occurred in about 3% stations only caused by Phenanthrene(Phe) and Dibenzo(a,h)anthracene(DBA). Here freshwater acute effects data together with saltwater data were used for SSD model. And this method could quickly give the rational risk information, and achieved our objective that compared the spatial difference of risk levels among three compartments. The results confirmed that the use of freshwater acute effects data from the ECOTOX database together with saltwater effects data is acceptable for risk assessment purposes in estuary.

  4. INTERSTELLAR ICES AS WITNESSES OF STAR FORMATION: SELECTIVE DEUTERATION OF WATER AND ORGANIC MOLECULES UNVEILED

    SciTech Connect

    Cazaux, S.; Spaans, M.; Caselli, P.

    2011-11-10

    Observations of star-forming environments revealed that the abundances of some deuterated interstellar molecules are markedly larger than the cosmic D/H ratio of 10{sup -5}. Possible reasons for this pointed to grain surface chemistry. However, organic molecules and water, which are both ice constituents, do not enjoy the same deuteration. For example, deuterated formaldehyde is very abundant in comets and star-forming regions, while deuterated water rarely is. In this paper, we explain this selective deuteration by following the formation of ices (using the rate equation method) in translucent clouds, as well as their evolution as the cloud collapses to form a star. Ices start with the deposition of gas-phase CO and O onto dust grains. While reaction of oxygen with atoms (H or D) or molecules (H{sub 2}) yields H{sub 2}O (HDO), CO only reacts with atoms (H and D) to form H{sub 2}CO (HDCO, D{sub 2}CO). As a result, the deuteration of formaldehyde is sensitive to the gas D/H ratio as the cloud undergoes gravitational collapse, while the deuteration of water strongly depends on the dust temperature at the time of ice formation. These results reproduce well the deuterium fractionation of formaldehyde observed in comets and star-forming regions and can explain the wide spread of deuterium fractionation of water observed in these environments.

  5. Hydrophobic molecules slow down the hydrogen-bond dynamics of water.

    PubMed

    Bakulin, Artem A; Pshenichnikov, Maxim S; Bakker, Huib J; Petersen, Christian

    2011-03-17

    We study the spectral and orientational dynamics of HDO molecules in solutions of tertiary-butyl-alcohol (TBA), trimethyl-amine-oxide (TMAO), and tetramethylurea (TMU) in isotopically diluted water (HDO:D(2)O and HDO:H(2)O). The spectral dynamics are studied with femtosecond two-dimensional infrared spectroscopy and the orientational dynamics with femtosecond polarization-resolved vibrational pump-probe spectroscopy. We observe a strong slowing down of the spectral diffusion around the central part of the absorption line that increases with increasing solute concentration. At low concentrations, the fraction of water showing slow spectral dynamics is observed to scale with the number of methyl groups, indicating that this effect is due to slow hydrogen-bond dynamics in the hydration shell of the methyl groups of the solute molecules. The slowing down of the vibrational frequency dynamics is strongly correlated with the slowing down of the orientational mobility of the water molecules. This correlation indicates that these effects have a common origin in the effect of hydrophobic molecular groups on the hydrogen-bond dynamics of water.

  6. H^- and D^- channels of Dissociative Electron Attachment to water molecules

    NASA Astrophysics Data System (ADS)

    Adaniya, Hidehito; Rudek, Benedikt; Osipov, Timur; Lee, Sun; Weber, Thorsten; Hertlein, Marcus; Schoeffler, Markus; Prior, Mike; Belkacem, Ali

    2009-05-01

    A COLTRIM technique is modified to measure the kinetic energy and angular distribution of H^- and D^- ions arising from dissociative electron attachment to water and heavy water molecules. A low energy pulsed electron, an effusive water target, a pulsed extraction plate are used in combination with the COLTRIMS spectrometer. The spectrometer carries an electrostatic lens system to compensate the effusiveness of the target. This technique is applied to study the H^- and D^- channels in the three Feshbach resonances of water and heavy water anion. The measured kinetic energy release will give the energy partitioning among the fragments, and the means to identify the two-body and three-body breakup channels. The angular distribution of the H^-(D^-) ions with respect to the electron beam is found to reflect well the breakup dynamics of the H2O^- at the dissociation. The experimental results are compared with the theoretical predictions.

  7. Temperature dependence of local solubility of hydrophobic molecules in the liquid-vapor interface of water.

    PubMed

    Abe, Kiharu; Sumi, Tomonari; Koga, Kenichiro

    2014-11-14

    One important aspect of the hydrophobic effect is that solubility of small, nonpolar molecules in liquid water decreases with increasing temperature. We investigate here how the characteristic temperature dependence in liquid water persists or changes in the vicinity of the liquid-vapor interface. From the molecular dynamics simulation and the test-particle insertion method, the local solubility Σ of methane in the liquid-vapor interface of water as well as Σ of nonpolar solutes in the interface of simple liquids are calculated as a function of the distance z from the interface. We then examine the temperature dependence of Σ under two conditions: variation of Σ at fixed position z and that at fixed local solvent density around the solute molecule. It is found that the temperature dependence of Σ at fixed z depends on the position z and the system, whereas Σ at fixed local density decreases with increasing temperature for all the model solutions at any fixed density between vapor and liquid phases. The monotonic decrease of Σ under the fixed-density condition in the liquid-vapor interface is in accord with what we know for the solubility of nonpolar molecules in bulk liquid water under the fixed-volume condition but it is much robust since the solvent density to be fixed can be anything between the coexisting vapor and liquid phases. A unique feature found in the water interface is that there is a minimum in the local solubility profile Σ(z) on the liquid side of the interface. We find that with decreasing temperature the minimum of Σ grows and at the same time the first peak in the oscillatory density profile of water develops. It is likely that the minimum of Σ is due to the layering structure of the free interface of water.

  8. [Genetic variation at the pantophysin (PanI) locus in North-East Arctic cod Gadus morhua L. (Gadiformes: Gadidae) population in the Barents Sea and adjacent waters].

    PubMed

    Makeenko, G A; Volkov, A A; Mugue, N S; Zelenina, D A

    2014-12-01

    We investigated polymorphisms in the pantophysin gene (Pan I locus) in a population of North-East Arctic cod, Gadus morhua L., throughout its foraging area in the Barents Sea and adjacent waters. Correlations between the frequencies of Pan I alleles and habitat conditions, such as depth and temperature, were explored. This study was based on a large number of specimens (2210 individuals) of different age and wide geographic sampling coverage. The frequency of the Pan I(A) allele, a known genetic marker of coastal cod, varied from zero to 0.47. Allele frequencies correlated with depth at the sampling location but not with bottom water temperatures. We observed variations in Pan I(A) frequencies among different age cohorts from the same area. The most prominent shift in Pan I polymorphism was detected at the early stages of the fish life cycle, between pelagic juveniles and benthic cod. We found that the Pan I(A) allele frequency in pelagic yearling cod was essentially same throughout the studied areas in the Barents Sea. In turn, juveniles settling at the northern and deep water locations showed a significant decrease in the allele frequency. In contrast, the frequency of the Pan I(A) allele remained constant in juveniles settling in shallow waters when compared to the pelagic stage. These results confirm the selective nature of the cod Pan I locus and indicate that selection process acting on individuals with different genotypes at the Pan I locus leads to the formation of a stable spatial distribution of allele frequencies observed in adult cod.

  9. Effects of brush management on the hydrologic budget and water quality in and adjacent to Honey Creek State Natural Area, Comal County, Texas, 2001--10

    USGS Publications Warehouse

    Banta, J. Ryan; Slattery, Richard N.

    2012-01-01

    Woody vegetation, including ashe juniper (Juniperus ashei), has encroached on some areas in central Texas that were historically oak grassland savannah. Encroachment of woody vegetation is generally attributed to overgrazing and fire suppression. Removing the ashe juniper and allowing native grasses to reestablish in the area as a brush management conservation practice (hereinafter referred to as "brush management") might change the hydrology in the watershed. These hydrologic changes might include changes to surface-water runoff, evapotranspiration, or groundwater recharge. The U.S. Geological Survey (USGS), in cooperation with Federal, State, and local partners, examined the hydrologic effects of brush management in two adjacent watersheds in Comal County, Tex. Hydrologic data were collected in the watersheds for 3-4 years (pre-treatment) depending on the type of data, after which brush management occurred on one watershed (treatment watershed) and the other was left in its original condition (reference watershed). Hydrologic data were collected in the study area for another 6 years (post-treatment). These hydrologic data included rainfall, streamflow, evapotranspiration, and water quality. Groundwater recharge was not directly measured, but potential groundwater recharge was calculated by using a simplified mass balance approach. This fact sheet summarizes highlights of the study from the USGS Scientific Investigations Report on which it is based.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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 108-109 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 ṡ 108 V m-1) when in the fluid phase with a monovalent counter-ion and ˜1.4 V (˜2.8 ṡ 108 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-phosphorylcholine (DMPC

  11. Local thermodynamics of the water molecules around single- and double-stranded DNA studied by grid inhomogeneous solvation theory

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Thermodynamic properties of water molecules around single- and double-stranded DNAs (ssDNAs and dsDNAs) with different sequences were investigated using grid inhomogeneous solvation theory. Free energies of water molecules solvating the minor groove of dsDNAs are lower than those near ssDNAs, while water molecules should be released during the formation of dsDNA. Free energies of water molecules around dsDNA are lower than those around ssDNA even in the second and third hydration shells. Our findings will help to clarify the role of water molecules in the formation of dsDNA from ssDNAs, thus facilitating the designs of drugs or nanomaterials using DNA.

  12. Double ionization of single oriented water molecules by electron impact: Second-order Born description

    SciTech Connect

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

    2011-06-15

    The double ionization of isolated water molecules fixed in space is investigated within a theoretical approach based on the second-order Born approximation. Electron angular distributions have been studied for specific kinematical conditions. The three usual mechanisms, the shake-off and the two two-step mechanisms, have been identified. A significant contribution of the two-step mechanism is clearly visible for some particular kinematics.

  13. Effects of water molecules of Ar-Cs MHD disk generator operated with strong MHD interaction

    SciTech Connect

    Ishikawa, M.; Kosugi, A.; Inui, Y.; Kabashima, S.

    1998-07-01

    Effects of water molecule impurity are studied on performance of a disk type MHD generator operated with Ar-Cs weakly ionized plasma. To reveal phenomena for a wide range of operation conditions, time-dependent one-dimensional analyses are carried out, where an up-wind, second order Chakravarthy TVD scheme is applied for the gasdynamics, while a Galerkin FEM is used for the electrodynamics. A simplified model is used for the water molecule impurity, where total effects of nonelastic collision between electrons and water molecules are estimated by the collision loss factor of electrons and also the electron momentum-transfer collision frequency is taken into account. The collision loss factor of electrons and the electron momentum-transfer collision frequency are taken from references, and the loss factor is assumed to be 700 independently of the electron temperature. On the Fuji-1 facilities at Tokyo Institute Technology, Japan, series of experiment A4105 were carried out with the Disk F-4 generator. Ar was heated with the heat-exchanger heated by the natural gas-air combustion and the metal cesium was used as the seeding material, while SCM maintained the magnetic field of 4.7 T at the center of disk and the very strong MHD interaction was realized. The thermal input was about 3 MW, the electrical output was about 500 kW with the enthalpy extraction ratio of about 17%. The numerical analyses have shown that the water molecule enhances the ionization instability at the low voltage loading because of insufficient Joule heating for electrons. The generator performance is degraded and the strong MHD interaction between the unstable plasma and the flow field induces slow and fast moving shock waves, leading to the very complicated flow field. The fast and slow moving shocks collide with each other, merge into a sharp shock moving downward, and then the shock front moves back slightly to maintain the pressure balance, collides again with another weak moving shock, and

  14. Influence of Organic Chemicals on Water Molecule Bridges in Soil Organic Matter of a Sapric Histosol.

    PubMed

    Ondruch, Pavel; Kučerík, Jiri; Steinmetz, Zacharias; Schaumann, Gabriele E

    2017-03-02

    Water molecules in soil organic matter (SOM) can form clusters bridging neighboring molecular segments (water molecule bridges; WaMB). WaMB are hypothesized to enhance physical entrapment of organic chemicals and to control the rigidity of the SOM supramolecular structure. However, the understanding of WaMB dynamics in SOM is still limited. We investigated the relation between WaMB stability and the physicochemical properties of their environment by treating a sapric histosol with various solvents and organic chemicals. Based on predictions from molecular modeling, we hypothesized that the stability of WaMB, measured by differential scanning calorimetry, increases with decreasing ability of a chemical to interact with water molecules of the WaMB. The interaction ability between WaMB and the chemicals was characterized by linear solvation energy relationships. WaMB stability in solvent-treated samples was found to decrease with increasing ability of a solvent to undergo H-donor/acceptor interactions. Spiking with an organic chemical stabilized (naphthalene) or destabilized (phenol) the WaMB. WaMB stability and matrix rigidity were generally reduced strongly and fast when hydrophilic chemicals entered the soil. The physicochemical aging following this destabilization is slow, but leads to a successive WaMB stabilization and matrix stiffening.

  15. WaterLOGSY NMR experiments in conjunction with molecular-dynamics simulations identify immobilized water molecules that bridge peptide mimic MDWNMHAA to anticarbohydrate antibody SYA/J6.

    PubMed

    Szczepina, Monica G; Bleile, Dustin W; Müllegger, Johannes; Lewis, Andrew R; Pinto, B Mario

    2011-10-04

    X-ray crystallographic data of the carbohydrate mimic MDWNMHAA when bound to an anti-Shigella flexneri Y mAb SYA/J6 indicate the immobilization of water molecules, that is, the presence of "bound" waters, in the active site. Water Ligand Observed via Gradient Spectroscopy (WaterLOGSY) was used in conjunction with saturation transfer difference (STD)-NMR spectroscopy to probe the existence of immobilized water molecules in the complex of MDWNMHAA 1 bound to mAb SYA/J6. Molecular dynamics simulations using the ZymeCAD Molecular Dynamics platform were then used to specify the likely locations of these water molecules. Of note, those waters involved in providing complementarity between the peptide and mAb SYA/J6 remained throughout the course of the simulation. Together, the experimental and computational protocols have been used to identify the bound water molecules present in the antibody-peptide complex.

  16. How strongly do hydrogen and water molecules stick to carbon nanomaterials?

    NASA Astrophysics Data System (ADS)

    Al-Hamdani, Yasmine S.; Alfè, Dario; Michaelides, Angelos

    2017-03-01

    The interaction strength of molecular hydrogen and water to carbon nanomaterials is relevant to, among many applications, hydrogen storage, water treatment, and water flow. However, accurate interaction energies for hydrogen and water with carbon nanotubes (CNTs) remain scarce despite the importance of having reliable benchmark data to inform experiments and to validate computational models. Here, benchmark fixed-node diffusion Monte Carlo (DMC) interaction energies are provided for hydrogen and water monomers inside and outside a typical zigzag CNT. The DMC interaction energies provide valuable insight into molecular interactions with CNTs in general and are also expected to be particularly relevant to gas uptake studies on CNTs. In addition, a selection of density functional theory (DFT) exchange-correlation (xc) functionals and force field potentials that ought to be suitable for these systems is compared. An unexpected variation is found in the performance of DFT van der Waals (vdW) models in particular. An analysis of the peculiar discrepancy between different vdW models indicates that medium-range correlation (at circa 3 to 5 Å) plays a key role inside CNTs and is poorly predicted by some vdW models. Using accurate reference information, this work reveals which xc functionals and force fields perform well for molecules interacting with CNTs. The findings will be valuable to future work on these and related systems that involve molecules interacting with low-dimensional systems.

  17. Aquatic risk assessment of pesticides in surface waters in and adjacent to the Everglades and Biscayne National Parks: II. Probabilistic analyses.

    PubMed

    Carriger, John F; Rand, Gary M

    2008-10-01

    A screening-level aquatic probabilistic risk assessment was completed to determine the potential risks of organic pesticides found in surface waters of the C-111 freshwater basin (11 sites at the east boundary of the Everglades National Park) and adjacent estuarine tidal zones (two sites in northeast Florida Bay, one site in south Biscayne Bay) in south Florida. It followed the US Environmental Protection Agency (USEPA) ecological risk framework and focused only on the acute and chronic risks of endosulfan and chlorpyrifos individually and jointly with atrazine, metolachlor, and malathion by comparing distributions of surface water exposure concentrations with the distributions of species toxicity data. The highest risk of acute effects was associated with endosulfan exposure to freshwater arthropods at S-178/site C on the C-111 system, followed by endosulfan effects to estuarine arthropods at Joe Bay in northeast Florida Bay. The highest risk of acute effects from joint toxicity of pesticides was to estuarine arthropods in Joe Bay followed by freshwater arthropods in S-178/site C. For fish, the highest acute risk was for endosulfan at S-178/site C. There was low potential for acute risk of endosulfan to fish at estuarine sites. Joint probability curves indicated that the majority of potential risks to arthropods and fish were due to endosulfan concentrations and not to chlorpyrifos, at S-178/site C. In addition, the highest risk of acute effects for saltwater organisms was in Joe Bay, which receives water from the C-111. The potential risk of chronic effects from pesticide exposures was minimal at fresh- and saltwater sites except at S-178/site C, where endosulfan concentrations showed the highest exceedence of species toxicity values. In general, potential risks were higher in February than June.

  18. Adsorption of water molecules on selected charged sodium-chloride clusters.

    PubMed

    Bradshaw, James A; Gordon, Sidney L; Leavitt, Andrew J; Whetten, Robert L

    2012-01-12

    The adsorption of water molecules (H(2)O) on sodium chloride cluster cations and anions was studied at 298 K over a mass range of 100-1200 amu using a custom-built laser desorption ionization reactor and mass spectrometer. Under the conditions used, the cations Na(3)Cl(2)(+) and Na(4)Cl(3)(+) bind up to three water molecules, whereas the larger cations, Na(5)Cl(4)(+) to Na(19)Cl(18)(+), formed hydrates with one or two only. The overall trend is a decrease in hydration with increasing cluster size, with an abrupt drop occurring at the closed-shell Na(14)Cl(13)(+). As compared to the cluster cations, the cluster anions showed almost no adsorption. Among smaller clusters, a weak adsorption of one water molecule was observed for the cluster anions Na(6)Cl(7)(-) and Na(7)Cl(8)(-). In the higher mass region, a substantial adsorption of one water molecule was observed for Na(14)Cl(15)(-). Density functional theory (DFT) computations were carried out for the adsorption of one molecule of H(2)O on the cations Na(n)Cl(n-1)(+), for n = 2-8, and the anions Na(n)Cl(n+1)(-), for n = 1-7. For each ion, the structure of the hydrate, the hydration energy, and the standard-state enthalpy, entropy, and Gibbs energy of hydration at 298 K were computed. In addition, it was useful to compute the distortion energy, defined as the electronic energy lost due to weakening of the Na-Cl bonds upon adsorption of H(2)O. The results show that strong adsorption of a H(2)O molecule occurs for the linear cations only at an end Na ion and for the nonlinear cations only at a corner Na ion bonded to two Cl ions. An unexpected result of the theoretical investigation for the anions is that certain low-energy isomers of Na(6)Cl(7)(-) and Na(7)Cl(8)(-) bind H(2)O strongly enough to produce the observed weak adsorption. The possible implications of these results for the initial hydration of extended NaCl surfaces are discussed.

  19. Infrared spectroscopy of water clusters co-adsorbed with hydrogen molecules on a sodium chloride film

    NASA Astrophysics Data System (ADS)

    Yamakawa, Koichiro; Fukutani, Katsuyuki

    2016-06-01

    Hydrogen gas containing a trace of water vapor was dosed on a vacuum-evaporated sodium chloride film at 13 K, and water clusters formed on the substrate were investigated by infrared absorption spectroscopy. Absorption bands due to (H2O)n clusters with n = 3-6 and an induced absorption band due to hydrogen were clearly observed. With increasing gas dosage, the intensities of the cluster bands increased linearly while the intensity of the hydrogen band was constant. This suggests that the water clusters were formed in two-dimensional matrices of hydrogen. We found that the water clusters did exist on the surface upon heating even after the hydrogen molecules had desorbed. A further rise of the substrate temperature up to 27 K yielded the formation of larger clusters, (H2O)n with n > 6 . We also discuss the origins of the two bands of the trimer in terms of pseudorotation and a metastable isomer.

  20. Geology and ground-water resources of the Two Medicine unit and adjacent areas, Blackfeet Indian Reservation, Montana, with a section on chemical quality of water

    USGS Publications Warehouse

    Paulson, Q.F.; Zimmerman, Tom V.; Langford, Russell H.

    1965-01-01

    The Two Medicine Irrigation Unit, on the Blackfeet Indian Reservation of northern Montana, is irrigated by water diverted from Two Medicine Creek. Waterlogging because of overapplication of water and locally inadequate subsurface drainage is a serious problem. This study was undertaken by the U.S. Geological Survey in cooperation with the U.S. Bureau of Indian Affairs to evaluate the problem and to suggest remedies. For this study, the geology was mapped, and data concerning 129 wells and test holes were gathered. The water level in 63 wells was measured periodically. Three test holes were drilled and 4 single-well and 1 multiple-well pump tests were made. Nineteen samples of ground water were collected and analyzed chemically, and applied irrigation water was analyzed periodically.

  1. The interaction of Al atoms with water molecules: A theoretical study.

    PubMed

    Alvarez-Barcia, S; Flores, J R

    2009-11-07

    The interaction of individual Al atoms with water molecules has been studied from the point of view of the energy by means of ab initio and DFT calculations in order to find the pathways for the generation of HAlOH(H(2)O)(n) or AlOH(H(2)O)(n)+H. The potential energy surface of the Al(H(2)O)(n+1) (n=0-3) systems has been explored for local minima and the relevant saddle points. The interaction of Al and several water molecules tends to produce low-lying local minima in which (for n=2-3) Al is "inserted" into relatively compact structures of water molecules, so typically a ring is formed containing an AlOH(2) moiety. Isomerization of such moiety into HAlOH(H(2)O)(n) may take place through saddle points of the "relay" type; however those saddle points lie very close to AlOH(2)(H(2)O)(n-1)+H(2)O, which means that such isomerization process has to compete with a water-elimination process. Larger systems Al(H(2)O)(n+1) (n=4-7) have also been computed by means of a DFT method, as a first step to predict the behavior of isolated Al atoms in even larger clusters or in the bulk. Finally, an effective fragment potential method has been employed to simulate those large clusters together with a polarizable continuum model to take into account the effect of the bulk. Our results suggest that the reaction should take place in inert matrices and in the bulk. We also conclude that HAlOH(H(2)O)(n) and AlOH(H(2)O)(n) could be the intermediates involved in the generation of hydrogen by the interaction of Al atoms with water, so their production would be the critical step of such process.

  2. 33 CFR 334.730 - Waters of Santa Rosa Sound and Gulf of Mexico adjacent to Santa Rosa Island, Air Force Proving...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Gulf of Mexico adjacent to Santa Rosa Island, Air Force Proving Ground Command, Eglin Air Force Base... Sound and Gulf of Mexico adjacent to Santa Rosa Island, Air Force Proving Ground Command, Eglin Air... regulations. (1) Experimental test operations will be conducted by the U.S. Air Force within the...

  3. 33 CFR 334.730 - Waters of Santa Rosa Sound and Gulf of Mexico adjacent to Santa Rosa Island, Armament Center...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Gulf of Mexico adjacent to Santa Rosa Island, Armament Center, Eglin Air Force Base, Fla. 334.730... Mexico adjacent to Santa Rosa Island, Armament Center, Eglin Air Force Base, Fla. (a) The areas—(1) The...) Experimental test operations will be conducted by the U.S. Air Force (USAF) within the danger zone....

  4. 33 CFR 334.730 - Waters of Santa Rosa Sound and Gulf of Mexico adjacent to Santa Rosa Island, Armament Center...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Gulf of Mexico adjacent to Santa Rosa Island, Armament Center, Eglin Air Force Base, Fla. 334.730... Mexico adjacent to Santa Rosa Island, Armament Center, Eglin Air Force Base, Fla. (a) The areas—(1) The...) Experimental test operations will be conducted by the U.S. Air Force (USAF) within the danger zone....

  5. 33 CFR 334.730 - Waters of Santa Rosa Sound and Gulf of Mexico adjacent to Santa Rosa Island, Air Force Proving...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Gulf of Mexico adjacent to Santa Rosa Island, Air Force Proving Ground Command, Eglin Air Force Base... Sound and Gulf of Mexico adjacent to Santa Rosa Island, Air Force Proving Ground Command, Eglin Air... regulations. (1) Experimental test operations will be conducted by the U.S. Air Force within the...

  6. 33 CFR 334.730 - Waters of Santa Rosa Sound and Gulf of Mexico adjacent to Santa Rosa Island, Armament Center...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Gulf of Mexico adjacent to Santa Rosa Island, Armament Center, Eglin Air Force Base, Fla. 334.730... Mexico adjacent to Santa Rosa Island, Armament Center, Eglin Air Force Base, Fla. (a) The areas—(1) The...) Experimental test operations will be conducted by the U.S. Air Force (USAF) within the danger zone....

  7. Simulation of ground-water flow and the movement of saline water in the Hueco Bolson aquifer, El Paso, Texas, and adjacent areas

    USGS Publications Warehouse

    Groschen, George E.

    1994-01-01

    Results of the projected withdrawal simulations from 1984-2000 indicate that the general historical trend of saline-water movement probably will continue. The saline water in the Rio Grande alluvium is the major source of saline-water intrusion into the freshwater zone throughout the historical period and into the future on the basis of simulation results. Some saline water probably will continue to move downward from the Rio Grande alluvium to the freshwater below. Injection of treated sewage effluent into some wells will create a small zone of freshwater containing slightly increased amounts of dissolved solids in the northern area of the Texas part of the Hueco bolson aquifer. Many factors, such as well interference, pumping schedules, and other factors not specifically represented in the regional simulation, can substantially affect dissolved-solids concentrations at individual wells.

  8. Geologic Assessment of Undiscovered, Technically Recoverable Coalbed-Gas Resources in Cretaceous and Tertiary Rocks, North Slope and Adjacent State Waters, Alaska

    USGS Publications Warehouse

    Roberts, Stephen B.

    2008-01-01

    The purpose of the U.S. Geological Survey's (USGS) National Oil and Gas Assessment is to develop geology-based hypotheses regarding the potential for additions to oil and gas reserves in priority areas of the United States, focusing on the distribution, quantity, and availability of oil and natural gas resources. The USGS has completed an assessment of the undiscovered, technically recoverable coalbed-gas resources in Cretaceous and Tertiary rocks underlying the North Slope and adjacent State waters of Alaska (USGS Northern Alaska Province 5001). The province is a priority Energy Policy and Conservation Act (EPCA) province for the National Assessment because of its potential for oil and gas resources. The assessment of this province is based on geologic principles and uses the total petroleum system concept. The geologic elements of a total petroleum system include hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (stratigraphy, sedimentology, petrophysical properties), and hydrocarbon traps (trap formation and timing). In the Northern Alaska Province, the USGS used this geologic framework to define one composite coalbed gas total petroleum system and three coalbed gas assessment units within the petroleum system, and quantitatively estimated the undiscovered coalbed-gas resources within each assessment unit.

  9. Reactions of water and C1 molecules on carbide and metal-modified carbide surfaces.

    PubMed

    Wan, Weiming; Tackett, Brian M; Chen, Jingguang G

    2017-02-23

    The formation of carbides can significantly modify the physical and chemical properties of the parent metals. In the current review, we summarize the general trends in the reactions of water and C1 molecules over transition metal carbide (TMC) and metal-modified TMC surfaces and thin films. Although the primary focus of the current review is on the theoretical and experimental studies of reactions of C1 molecules (CO, CO2, CH3OH, etc.), the reactions of water will also be reviewed because water plays an important role in many of the C1 transformation reactions. This review is organized by discussing separately thermal reactions and electrochemical reactions, which provides insights into the application of TMCs in heterogeneous catalysis and electrocatalysis, respectively. In thermal reactions, we discuss the thermal decomposition of water and methanol, as well as the reactions of CO and CO2 over TMC surfaces. In electrochemical reactions, we summarize recent studies in the hydrogen evolution reaction, electrooxidation of methanol and CO, and electroreduction of CO2. Finally, future research opportunities and challenges associated with using TMCs as catalysts and electrocatalysts are also discussed.

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

    SciTech Connect

    Isailovic, Slavica

    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.

  11. Effects of brush management on the hydrologic budget and water quality in and adjacent to Honey Creek State Natural Area, Comal County, Texas, 2001-10

    USGS Publications Warehouse

    Banta, J. Ryan; Slattery, Richard N.

    2011-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Natural Resources Conservation Service, the Edwards Region Grazing Lands Conservation Initiative, the Texas State Soil and Water Conservation Board, the San Antonio River Authority, the Edwards Aquifer Authority, Texas Parks and Wildlife, the Guadalupe Blanco River Authority, and the San Antonio Water System, evaluated the hydrologic effects of ashe juniper (Juniperus ashei) removal as a brush management conservation practice in and adjacent to the Honey Creek State Natural Area in Comal County, Tex. By removing the ashe juniper and allowing native grasses to reestablish in the area as a brush management conservation practice, the hydrology in the watershed might change. Using a simplified mass balance approach of the hydrologic cycle, the incoming rainfall was distributed to surface water runoff, evapotranspiration, or groundwater recharge. After hydrologic data were collected in adjacent watersheds for 3 years, brush management occurred on the treatment watershed while the reference watershed was left in its original condition. Hydrologic data were collected for another 6 years. Hydrologic data include rainfall, streamflow, evapotranspiration, and water quality. Groundwater recharge was not directly measured but potential groundwater recharge was calculated using a simplified mass balance approach. The resulting hydrologic datasets were examined for differences between the watersheds and between pre- and post-treatment periods to assess the effects of brush management. The streamflow to rainfall relation (expressed as event unit runoff to event rainfall relation) did not change between the watersheds during pre- and post-treatment periods. The daily evapotranspiration rates at the reference watershed and treatment watershed sites exhibited a seasonal cycle during the pre- and post-treatment periods, with intra- and interannual variability. Statistical analyses indicate the mean

  12. Does soil water saturation mobilize metals from riparian soils to adjacent surface water? A field monitoring study in a metal contaminated region.

    PubMed

    Van Laer, Liesbeth; Smolders, Erik

    2013-06-01

    In the Noorderkempen (NW Belgium), a large area (about 280 km(2)) is contaminated with cadmium (Cd) and zinc (Zn) due to historical pollution by the Zn smelters. Direct aquatic emissions of metals have diminished over time, however the surface water metal concentration largely exceeds quality standards, mainly during winter periods. Monitoring data were analyzed to reveal whether these fluctuations are related to seasonal redox reactions in associated contaminated riparian soils that drain into the rivers. A field survey was set up with soil pore-water and groundwater monitored for three years in transects of soil monitoring points perpendicular to rivers at contaminated and non-contaminated sites. Site averaged surface water concentrations of a 15 year dataset exceeded local quality standards 4 to 200-fold. Winter averaged metal concentrations significantly exceeded the corresponding summer values 1.3-1.8 (Zn) and 1.5-2.4 fold (Cd). Zinc and Cd concentrations in water were positively related to Fe and Mn but not to Ca, K or Na suggesting that redox reactions and not dilution processes are involved. In ground- and pore-water of the associated riparian soils, the concentrations of Zn fluctuate by the same order of magnitude as in surface water but were generally smaller than in the corresponding contaminated rivers. In addition, correlations of dissolved Zn with Fe and Mn were lacking. This analysis suggests that redox reactions in streams, and not in riparian soils, explain the seasonal trends of Zn and Cd in surface water. Hence, river sediments and not riparian soils may be the cause of the winter peaks of Zn and Cd in these rivers.

  13. Isotope geochemistry and fluxes of carbon and organic matter in tropical small mountainous river systems and adjacent coastal waters of the Caribbean

    USGS Publications Warehouse

    Moyer, Ryan; Bauer, James; Grottoli, Andrea

    2012-01-01

    Recent studies have shown that small mountainous rivers (SMRs) may act as sources of aged and/or refractory carbon (C) to the coastal ocean, which may increase organic C burial at sea and subsidize coastal food webs and heterotrophy. However, the characteristics and spatial and temporal variability of C and organic matter (OM) exported from tropical SMR systems remain poorly constrained. To address this, the abundance and isotopic character (δ13C and Δ14C) of the three major C pools were measured in two Puerto Rico SMRs with catchments dominated by different land uses (agricultural vs. non-agricultural recovering forest). The abundance and character of C pools in associated estuaries and adjacent coastal waters were also examined. Riverine dissolved and particulate organic C (DOC and POC, respectively) concentrations were highly variable with respect to land use and sampling month, while dissolved inorganic C (DIC) was significantly higher at all times in the agricultural catchment. In both systems, riverine DOC and POC ranged from modern to highly aged (2,340 years before present), while DIC was always modern. The agricultural river and irrigation canals contained very old DOC (1,184 and 2,340 years before present, respectively), which is consistent with findings in temperate SMRs and indicates that these tropical SMRs provide a source of aged DOC to the ocean. During months of high river discharge, OM in estuarine and coastal waters had C isotope signatures reflective of direct terrestrial input, indicating that relatively unaltered OM is transported to the coastal ocean at these times. This is also consistent with findings in temperate SMRs and indicates that C transported to the coastal ocean by SMRs may differ from that of larger rivers because it is exported from smaller catchments that have steeper terrains and fewer land-use types.

  14. Dangling OH Vibrations of Water Molecules in Aqueous Solutions of Aprotic Polar Compounds Observed in the Near-Infrared Regime.

    PubMed

    Sagawa, Naoya; Shikata, Toshiyuki

    2015-06-25

    Near-infrared (NIR) absorption spectrum measurements over a frequency range from 4000 to 12000 cm(-1) were employed to investigate the effects of the presence of solute compounds to vibrational modes of water molecules in aqueous solutions of some aprotic hydroneutral polar compounds with large dipole moments, such as nitro compounds and nitriles. The obtained NIR spectra for the aqueous solutions were decomposed into three components: free water, solute, and water molecules affected by the presence of solutes. Newly determined NIR spectra of affected water molecules were well-described with at least four absorption modes observed at 7040, 6850, 6450, and 5640 cm(-1) for both the nitro compounds and nitriles. The highest frequency mode at 7040 cm(-1) possessing the strongest intensity was assigned to the first stretching overtone of affected water hydroxy (O-H) groups, which are nonhydrogen bonded to other water molecules and dangling. The second highest frequency mode at 6850 cm(-1) was assigned to the first stretching overtone of affected water O-H groups hydrated to other (free) water molecules. The third mode at 6400 cm(-1) was attributed to a combination mode of the fundamental stretching of O-H and the first overtone of the O-H bending mode of the affected water molecules. The lowest frequency mode at 5640 cm(-1) was assigned to the combination mode of the fundamental O-H stretching mode, the fundamental O-H bending mode, and the hindered rotational (libration) mode of the affected water molecules. Because absorption intensities of the third and lowest frequency modes for water molecules affected by the solutes depended on the sizes of alkyl groups of polar solutes, these two modes possibly result from the contribution of hydrophobic hydration effects.

  15. Simulation of ground-water flow in coastal Georgia and adjacent parts of South Carolina and Florida-predevelopment, 1980, and 2000

    USGS Publications Warehouse

    Payne, Dorothy F.; Rumman, Malek Abu; Clarke, John S.

    2005-01-01

    A digital model was developed to simulate steady-state ground-water flow in a 42,155-square-mile area of coastal Georgia and adjacent parts of South Carolina and Florida. The model was developed to (1) understand and refine the conceptual model of regional ground-water flow, (2) serve as a framework for the development of digital subregional ground-water flow and solute-transport models, and (3) serve as a tool for future evaluations of hypothetical pumping scenarios used to facilitate water management in the coastal area. Single-density ground-water flow was simulated using the U.S. Geological Survey finite-difference code MODFLOW-2000 for mean-annual conditions during predevelopment (pre?1900) and the years 1980 and 2000. The model comprises seven layers: the surficial aquifer system, the Brunswick aquifer system, the Upper Floridan aquifer, the Lower Floridan aquifer, and the intervening confining units. A combination of boundary conditions was applied, including a general-head boundary condition on the top active cells of the model and a time-variable fixed-head boundary condition along part of the southern lateral boundary. Simulated heads for 1980 and 2000 conditions indicate a good match to observed values, based on a plus-or-minus 10-foot (ft) calibration target and calibration statistics. The root-mean square of residual water levels for the Upper Floridan aquifer was 13.0 ft for the 1980 calibration and 9.94 ft for the 2000 calibration. Some spatial patterns of residuals were indicated for the 1980 and 2000 simulations, and are likely a result of model-grid cell size and insufficiently detailed hydraulic-property and pumpage data in some areas. Simulated potentiometric surfaces for predevelopment, 1980, and 2000 conditions all show major flow system features that are indicated by estimated peotentiometric maps. During 1980?2000, simulated water levels at the centers of pumping at Savannah and Brunswick rose more than 20 ft and 8 ft, respectively, in

  16. Effects of a single water molecule on the OH + H2O2 reaction.

    PubMed

    Buszek, Robert J; Torrent-Sucarrat, Miquel; Anglada, Josep M; Francisco, Joseph S

    2012-06-21

    The effect of a single water molecule on the reaction between H(2)O(2) and HO has been investigated by employing MP2 and CCSD(T) theoretical approaches in connection with the aug-cc-PVDZ, aug-cc-PVTZ, and aug-cc-PVQZ basis sets and extrapolation to an ∞ basis set. The reaction without water has two elementary reaction paths that differ from each other in the orientation of the hydrogen atom of the hydroxyl radical moiety. Our computed rate constant, at 298 K, is 1.56 × 10(-12) cm(3) molecule(-1) s(-1), in excellent agreement with the suggested value by the NASA/JPL evaluation. The influence of water vapor has been investigated by considering either that H(2)O(2) first forms a complex with water that reacts with hydroxyl radical or that H(2)O(2) reacts with a previously formed H(2)O·OH complex. With the addition of water, the reaction mechanism becomes much more complex, yielding four different reaction paths. Two pathways do not undergo the oxidation reaction but an exchange reaction where there is an interchange between H(2)O(2)·H(2)O and H(2)O·OH complexes. The other two pathways oxidize H(2)O(2), with a computed total rate constant of 4.09 × 10(-12) cm(3) molecule(-1) s(-1) at 298 K, 2.6 times the value of the rate constant of the unassisted reaction. However, the true effect of water vapor requires taking into account the concentration of the prereactive bimolecular complex, namely, H(2)O(2)·H(2)O. With this consideration, water can actually slow down the oxidation of H(2)O(2) by OH between 1840 and 20.5 times in the 240-425 K temperature range. This is an example that demonstrates how water could be a catalyst in an atmospheric reaction in the laboratory but is slow under atmospheric conditions.

  17. Identification and characterization of the motion of water molecules in normal and deuterated pyromellitic acid dihydrate

    NASA Astrophysics Data System (ADS)

    Schajor, W.; Haeberlen, U.; Tegenfeldt, T.

    Proton wide-line, multiple-pulse, T1 and T1 ϱ measurements on single crystals of PMADH, and deuteron EFG measurements and bandshape analyses of spectra recorded from deuterated crystals of PMADH are reported. The wide-line and multiple-pulse proton results indicate that the water molecules in PMADH are flipping about their twofold symmetry axes. Both T1 and T1 ϱ were measured as a function of crystal orientation and temperature. Comparison of the experimental data with model calculations for T1 ϱ based on the established flipping motions of the water molecules shows that {1}/{T 1ϱ} is dominated by this process whereas {1}/{T 1} is not. The T1 ϱ data thus enable determination of the rate of the H 2O flips as a function of temperature. EFGs of the water deuterons in deuterated PMADH, measured at low and high temperatures, confirm the occurrence of the flips for D 2O in PMADH. The flips constitute an exchange process for the water deuterons. Bandshape analyses of single-crystal deuteron spectra recorded at temperatures covering the full range of exchange rates allowed determination of the flip rates of the D 2O molecules. The activation energies for the H 2O and D 2O flips are the same, Ea = 10 kcal/mol, within the limits of accuracy of the experiments. The frequency factors in the Arrhenius relation are 8.3 X 10 13 sec -1 (H 2O) and 2.6 X 10 13 sec -1 (D 2O).

  18. Effects of multivalent hexacyanoferrates and their ion pairs on water molecule dynamics measured with terahertz spectroscopy.

    PubMed

    DiTucci, Matthew J; Böhm, Fabian; Schwaab, Gerhard; Williams, Evan R; Havenith, Martina

    2017-02-27

    The valency of aqueous solutes plays a large role in determining the extent of ion-water dynamics, which can greatly influence the chemical and physical properties of solutions. In these experiments, broadband Fourier transform terahertz spectroscopy is used to probe perturbations to the low-frequency dynamics of water molecules by three different multivalent hexacyanoferrate salts. K3Fe(CN)6, K4Fe(CN)6 and Na4Fe(CN)6 were investigated as a function of concentration up to their solubility limits using spectral subtractions and fitting with damped harmonic lineshapes. Regions with subtle nonlinearities in amplitude with respect to solute concentration provide insight into ion-pairing events. The extent of nonlinearity suggests that ion pairs are major constituents in solution for all concentrations measured and is consistent with ion-pairing observed at millimolar concentrations by potentiometric and spectroscopic measurements. A lower estimate for the number of water molecules that are influenced by each ion is obtained from the damped harmonic fits. Values of 19, 28 and 25 water molecules with perturbed dynamics are obtained for KFe(CN)6(2-), KFe(CN)6(3-) and NaFe(CN)6(3-) ion pairs, respectively. These values represent dynamical perturbations into a second solvation shell and are consistent with the long-range structural effects observed in recent aqueous nanodrop spectroscopy experiments. Furthermore, the spectral absorptions for hexacyanoferrates are in agreement with a wide range of solutes studied previously using the developing methodology for interpreting terahertz spectra.

  19. Interactions of water, methanol and diethyl ether molecules with the surface of oxidized activated carbon

    NASA Astrophysics Data System (ADS)

    Salame, Issa I.; Bandosz, Teresa J.

    Two samples of oxidized activated carbon of wood origin were used as adsorbents of water, methanol, and diethyl ether. Structural and chemical characteristics of the samples' surfaces were obtained using adsorption of nitrogen and Boehm titration. The adsorption isotherms of water and methanol were measured using a volumetric apparatus whereas the adsorption of diethyl ether was studied by means of inverse gas chromatography at finite concentration. Then the isotherms at three different temperatures were used to calculate the isosteric heats of adsorption. The results showed that the strength of interaction depends on the porosity of the sample and its surface chemistry. The effect of surface chemistry and the presence of oxygenated groups are predominant in the case of water and the least important in the case of diethyl ether. This is the result of the chemical nature of the molecules, their sizes, and the relative strengths of the dispersive interactions in small pores in comparison with hydrogen bonding to surface functional groups.

  20. Shape-selective adsorption of aromatic molecules from water by tetramethylammonium-smectite

    USGS Publications Warehouse

    Lee, J.; Mortland, M.M.; Boyd, S.A.; Chiou, C.T.

    1989-01-01

    The adsorption of aromatic compounds by smectite exchanged with tetramethylammonium (TMA) has been studied. Aromatic compounds adsorbed by TMA-smectite are assumed to adopt a tilted orientation in a face-to-face arrangment with the TMA tetrahedra. The sorptive characteristics of TMA-smectite were influenced strongly by the presence of water. The dry TMA-smectite showed little selectivity in the uptake of benzen, toluene and xylene. In the presence of water, TMA-smectite showed a high degree of selectivity based on molecular size/shape, resulting in high uptake of benzene and progressively lower uptake of larger aromatic molecules. This selectivity appeared to result from the shrinkage of interlamellar cavities by water.

  1. Interfacial water molecules in SH3 interactions: a revised paradigm for polyproline recognition.

    PubMed

    Martin-Garcia, Jose M; Ruiz-Sanz, Javier; Luque, Irene

    2012-03-01

    In spite of its biomedical relevance, polyproline recognition is still not fully understood. The disagreement between the current description of SH3 (Src homology 3) complexes and their thermodynamic behaviour calls for a revision of the SH3-binding paradigm. Recently, Abl-SH3 was demonstrated to recognize its ligands by a dual binding mechanism involving a robust network of water-mediated hydrogen bonds that complements the canonical hydrophobic interactions. The systematic analysis of the SH3 structural database in the present study reveals that this dual binding mode is universal to SH3 domains. Tightly bound buried-interfacial water molecules were found in all SH3 complexes studied mediating the interaction between the peptide ligand and the domain. Moreover, structural waters were also identified in a high percentage of the free SH3 domains. A detailed analysis of the pattern of water-mediated interactions enabled the identification of conserved hydration sites in the polyproline-recognition region and the establishment of relationships between hydration profiles and the sequence of both ligands and SH3 domains. Water-mediated interactions were also systematically observed in WW (protein-protein interaction domain containing two conserved tryptophan residues), UEV (ubiquitin-conjugating enzyme E2 variant) and EVH-1 [Ena/VASP (vasodilator-stimulated phosphoprotein) homology 1] structures. The results of the present study clearly indicate that the current description of proline-rich sequence recognition by protein-protein interaction modules is incomplete and insufficient for a correct understanding of these systems. A new binding paradigm is required that includes interfacial water molecules as relevant elements in polyproline recognition.

  2. Effects of Disaccharide Sugars on Dynamics of Water Molecules: Dynamic Light Scattering and Dielectric Loss Spectroscopy Studies

    NASA Astrophysics Data System (ADS)

    Seo, Jeong-Ah; Kwon, Hyun-Joung; Kim, Hyung Kook; Hwang, Yoon-Hwae

    2008-02-01

    We studied the effects of disaccharide sugars (trehalose, sucrose, and maltose) on the dynamics of water molecules in sugar-water mixtures. We measured the acoustic phonons in sugar-water mixtures with different sugar contents by using a Sandercock Tandem 6-pass Febry-Petor interferometer and found that the Brillouin peak positions shifted to higher frequencies as the sugar concentration increased. We also measured the dielectric loss of hydrogen bonds in water molecules in sugar-water mixtures by using a Network analyzer with different sugar contents. The loss peak position in the dielectric loss spectra moved to lower frequencies as the sugar contents increased. The trehalose-water mixture showed the largest Brillouin peak shift and relaxation time change with increasing sugar content among three disaccharides indicating that the effect of trehalose on the dynamics of water molecules is the strongest. This unique property of trehalose sugar might be the origin of the superior bio-protection ability of trehalose.

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

    NASA Astrophysics Data System (ADS)

    Shepelenko, S. O.; Salnikov, A. S.; Rak, S. V.; Goncharova, E. P.; Ryzhikov, A. B.

    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

  4. 35 Years of Marine Natural Product Research in Sweden: Cool Molecules and Models from Cold Waters.

    PubMed

    Bohlin, Lars; Cárdenas, Paco; Backlund, Anders; Göransson, Ulf

    2017-01-01

    Currents efforts in marine biodiscovery have essentially focused on temperate to tropical shallow water organisms. With more than 6000 species of marine plants and animals, the Kosterfjord area has the richest marine biodiversity in Swedish waters, but it remains understudied. The overall objective of our marine pharmacognosy research is to explore and reveal the pharmacological potential of organisms from this poorly explored region. More generally, we wish to understand aspects of structure-activity relationships of chemical interactions in cold-water marine environment (shallow and deep). Our strategy is based on ecologically guided search for compounds through studies of physiology and organism interactions coupled to identification of bioactive molecules guided by especially in vivo assays. The research programme originated in the beginning of the 1980s with a broad screening of Swedish marine organisms using both in vitro and in vivo assays, resulting in isolation and identification of several different bioactive molecules. Two congenerous cyclopeptides, i.e. barettin and 8,9-dihydrobarettin, were isolated from the deep-sea sponge Geodia barretti, and structurally elucidated, guided by their antifouling activity and their affinity to a selection of human serotonin receptors. To optimize the activity a number of analogues of barettin were synthezised and tested for antifouling activity. Within the EU project BlueGenics, two larger homologous peptides, barrettides A and B, were isolated from G. baretti. Also, metabolic fingerprinting combined with sponge systematics was used to further study deep-sea natural product diversity in the genus Geodia. Finally, the chemical property space model 'ChemGPS-NP' has been developed and used in our research group, enabling a more efficient use of obtained compounds and exploration of possible biological activities and targets. Another approach is the broad application of phylogenetic frameworks, which can be used in

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

    NASA Astrophysics Data System (ADS)

    Zhou, Long; Xiu, Fangyuan; Qiu, Meng; Xia, Shuwei; Yu, Liangmin

    2017-01-01

    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 H2O is due to the formation of Fesbnd 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 μ3sbnd O as an intermediate product; the proton belonged to μ3sbnd O transferred to the neighbor surface μ2sbnd O as the dissociative configuration.

  6. Detection of water molecules in inert gas based plasma by the ratios of atomic spectral lines

    NASA Astrophysics Data System (ADS)

    Bernatskiy, A. V.; Ochkin, V. N.

    2017-01-01

    A new approach is considered to detect the water leaks in inert plasma-forming gas present in the reactor chamber. It is made up of the intensity ratio of D α and H α spectral lines in combination with O, Ar and Xe lines intensity. The concentrations of H2O, O, H and D particles have been measured with high sensitivity. At the D2 admixture pressure {{p}{{\\text{D}\\text{2}}}}   =  0.025 mbar, we used the acquisition time of 10 s to measure the rate of water molecules injected from the outside, Γ0  =  1.4 · 10-9 mbar · m3 · s-1, and the incoming water molecules to plasma, Γ  =  5 ·10-11 mbar · m3 · s-1. The scaling proves that at small D2 admixtures (10-4 mbar), the leaks with the rates Γ0  ≈  6 · 10-12 mbar · m3 · s-1 and Γ  ≈  2 · 10-13 mbar · m3 · s-1 can be detected and measured. The difference between Γ0 and Γ values is due to the high degree of H2O dissociation, which can be up to 97-98%.

  7. The Effect of Water Molecules on Mechanical Properties of Bamboo Microfibrils

    NASA Astrophysics Data System (ADS)

    Rahbar, Nima

    Bamboo fibers have higher strength-to-weight ratios than steel and concrete. The unique properties of bamboo fibers come from their natural composite structures that comprise mainly cellulose nanofibrils in a matrix of intertwined hemicellulose and lignin called lignin-carbohydrate complex (LCC). Here, we have utilized atomistic simulations to investigate the mechanical properties and mechanisms of interactions between these materials, in the presence of water molecules. Our results suggest that hemicellulose exhibits better mechanical properties and lignin shows greater tendency to adhere to cellulose nanofibrils. Consequently, the role of hemicellulose found to be enhancing the mechanical properties and lignin found to be providing the strength of bamboo fibers. The abundance of Hbonds in hemicellulose chains is responsible for improving the mechanical behavior of LCC. The strong van der Waals forces between lignin molecules and cellulose nanofibrils is responsible for higher adhesion energy between LCC/cellulose nanofibrils. We also found out that the amorphous regions of cellulose nanofibrils is the weakest interface in bamboo Microfibrils. In presence of water, the elastic modulus of lignin increases at low water content (less than 10 NSF CAREER Grant No. 1261284.

  8. Intramolecular cyclization of aspartic acid residues assisted by three water molecules: a density functional theory study

    NASA Astrophysics Data System (ADS)

    Takahashi, Ohgi; Kirikoshi, Ryota

    2014-01-01

    Aspartic acid (Asp) residues in peptides and proteins (l-Asp) are known to undergo spontaneous nonenzymatic reactions to form l-β-Asp, d-Asp, and d-β-Asp residues. The formation of these abnormal Asp residues in proteins may affect their three-dimensional structures and hence their properties and functions. Indeed, the reactions have been thought to contribute to aging and pathologies. Most of the above reactions of the l-Asp residues proceed via a cyclic succinimide intermediate. In this paper, a novel three-water-assisted mechanism is proposed for cyclization of an Asp residue (forming a gem-diol precursor of the succinimide) by the B3LYP/6-31 + G(d,p) density functional theory calculations carried out for an Asp-containing model compound (Ace-Asp-Nme, where Ace = acetyl and Nme = NHCH3). The three water molecules act as catalysts by mediating ‘long-range’ proton transfers. In the proposed mechanism, the amide group on the C-terminal side of the Asp residue is first converted to the tautomeric iminol form (iminolization). Then, reorientation of a water molecule and a conformational change occur successively, followed by the nucleophilic attack of the iminol nitrogen on the carboxyl carbon of the Asp side chain to form the gem-diol species. A satisfactory agreement was obtained between the calculated and experimental energetics.

  9. Pesticides in surface water, bed sediment, and ground water adjacent to commercial cranberry bogs, Lac du Flambeau Reservation, Vilas County, Wisconsin

    USGS Publications Warehouse

    Saad, David A.

    2005-01-01

    In samples from the Trout River, which is used as a source of water to maintain lake levels in the Corn Lakes, the only pesticides detected were the non-targeted compounds atrazine and deethyl atrazine, indicating it was not a source of targeted compounds detected in the Corn Lakes. Only two pesticides (chlorpyrifos and metolachlor) were detected in bed-sediment samples collected from the lakes; chlorpyrifos from Little Trout Lake and metolachlor from the Corn Lakes. Four pesticides (the targeted compounds napropamide and norflurazon and the non-targeted compounds atrazine and deethyl atrazine) were detected in ground-water samples from two of four sampled monitor wells. The highest ground-water concentrations (up to 0.14 ?g/L napropamide and 0.56 ?g/L norflurazon) were measured in samples from the monitoring well located directly downgradient from the Corn Lakes and commercial cranberry operations. No pesticides were detected in samples from the reference well located upgradient from the Corn Lakes and cranberry operations. Further study is needed to identify additional pesticides as well as chronic effects on aquatic organisms to determine whether cranberry-related pesticides affect the lake ecosystems of the Lac du Flambeau Reservation.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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 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 by continuum flow solvers, allowing for investigations into spatiotemporal scales inaccessible to atomistic simulations.

  11. Fall diets of red-breasted merganser (Mergus serrator) and walleye (Sander vitreus) in Sandusky Bay and adjacent waters of western Lake Erie

    USGS Publications Warehouse

    Bur, M.T.; Stapanian, M.A.; Bernhardt, G.; Turner, M.W.

    2008-01-01

    Although published studies indicate the contrary, there is concern among many sport anglers that migrating red-breasted mergansers (Mergus serrator) and other waterbirds pose a competitive threat to sport fish species such as walleye (Sander vitreus) in Lake Erie. We quantified the diet of autumn-migrant mergansers and walleye during 1998-2000 in Sandusky Bay and adjacent waters of western Lake Erie. We hypothesized that the diets of both predators would be similar in species composition, but because of different foraging ecologies their diets would differ markedly in size of prey consumed. In addition to predator samples, we used trawl data from the same general area as an index of prey availability. We found that mergansers fed almost exclusively on fish (nine species). Gizzard shad (Dorosoma cepedianum), emerald shiner (Notropis atherinoides) and round goby (Neogobius melanostomus) were consumed in the greatest numbers, most frequently and comprised the greatest biomass. Walleye fed exclusively on fish: gizzard shad, alewife (Alosa psuedoharengus) and emerald shiner were consumed in the greatest numbers, most frequently and comprised the greatest biomass. Diet overlap between mergansers and walleye was 67% by weight and 66% by species frequency. Mean total lengths of gizzard shad, emerald shiner and round goby found in walleye stomachs exceeded those captured in trawls by 47%, on average. Mean total lengths of gizzard shad, emerald shiner and round goby were greater in walleye stomachs than in merganser stomachs. Mean total lengths of emerald shiner and round goby were less in merganser stomachs than in trawls. Our results suggest that although the diets of walleye and mergansers overlapped considerably, mergansers generally consumed smaller fish than walleye. Given the abundance and diversity of prey species available, and the transient nature of mergansers on Lake Erie during migration, we conclude that competition for food between these species is minimal.

  12. Low-Frequency Variability of the Yellow Sea Cold Water Mass Identified from the China Coastal Waters and Adjacent Seas Reanalysis

    DTIC Science & Technology

    2015-01-01

    it does not display a currently valid OMB control number. 1. REPORT DATE 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4 ...In Section 4 , we investigate the interannual and decadal vari- ability of the YSCWM and discuss the relationship between the YSCWM and the three...higher than that of the surrounding water in winter. 4 Advances in Meteorology Section of 38.667∘N Section of 38.667∘N Section of 36.167∘N Section of

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Energy deposition model based on electron scattering cross section data from water molecules

    NASA Astrophysics Data System (ADS)

    Muñoz, A.; Oiler, J. C.; Blanco, F.; Gorfinkiel, J. D.; Limão-Vieira, P.; Maira-Vidal, A.; Borge, M. J. G.; Tengblad, O.; Huerga, C.; Téllez, M.; García, G.

    2008-10-01

    A complete set of electrons scattering cross sections by water molecules over a broad energy range, from the me V to the Me V ranges, is presented in this study. These data have been obtained by combining experiments and calculations and cover most relevant processes, both elastic and inelastic, which can take place in the considered energy range. A new Monte Carlo simulation programme has been developed using as input parameter these cross sectional data as well as experimental energy loss spectra. The simulation procedure has been applied to obtain electron tracks and energy deposition plots in water when irradiated by a Ru-106 plaque as those used for brachyteraphy of ocular tumours. Finally, the low energy electron tracks provided by the present model have been compared with those obtained with other codes available in the literature

  15. Water and complex organic molecules in the warm inner regions of solar-type protostars

    NASA Astrophysics Data System (ADS)

    Coutens, A.; Jørgensen, J. K.; Persson, M. V.; Lykke, J. M.; Taquet, V.; van Dishoeck, E. F.; Vastel, C.; Wampfler, S. F.

    2015-12-01

    Water and complex organic molecules play an important role in the emergence of Life. They have been detected in different types of astrophysical environments (protostars, prestellar cores, outflows, protoplanetary disks, comets, etc). In particular, they show high abundances towards the warm inner regions of protostars, where the icy grain mantles thermally desorb. Can a part of the molecular content observed in these regions be preserved during the star formation process and incorporated into asteroids and comets, that can deliver it to planetary embryos through impacts? By comparison with cometary studies, interferometric observations of solar-type protostars can help to address this important question. We present recent results obtained with the Plateau de Bure interferometer about water deuteration, glycolaldehyde and ethylene glycol towards the low-mass protostar NGC 1333 IRAS2A.

  16. Patterns of deep-water coral diversity in the Caribbean Basin and adjacent southern waters: an approach based on records from the R/V Pillsbury expeditions.

    PubMed

    Hernández-Ávila, Iván

    2014-01-01

    The diversity of deep-water corals in the Caribbean Sea was studied using records from oceanographic expeditions performed by the R/V Pillsbury. Sampled stations were sorted according to broad depth ranges and ecoregions and were analyzed in terms of species accumulation curves, variance in the species composition and contributions to alpha, beta and gamma diversity. According to the analysis of species accumulation curves using the Chao2 estimator, more diversity occurs on the continental slope (200-2000 m depth) than on the upper continental shelf (60-200 m depth). In addition to the effect of depth sampling, differences in species composition related to depth ranges were detected. However, the differences between ecoregions are dependent on depth ranges, there were fewer differences among ecoregions on the continental slope than on the upper continental shelf. Indicator species for distinctness of ecoregions were, in general, Alcyonaria and Antipatharia for the upper continental shelf, but also the scleractinians Madracis myriabilis and Cladocora debilis. In the continental slope, the alcyonarian Placogorgia and the scleractinians Stephanocyathus and Fungiacyathus were important for the distinction of ecoregions. Beta diversity was the most important component of gamma diversity in the Caribbean Basin. The contribution of ecoregions to alpha, beta and gamma diversity differed with depth range. On the upper continental shelf, the Southern Caribbean ecoregion contributed substantially to all components of diversity. In contrast, the northern ecoregions contributed substantially to the diversity of the Continental Slope. Strategies for the conservation of deep-water coral diversity in the Caribbean Basin must consider the variation between ecoregions and depth ranges.

  17. Patterns of Deep-Water Coral Diversity in the Caribbean Basin and Adjacent Southern Waters: An Approach based on Records from the R/V Pillsbury Expeditions

    PubMed Central

    Hernández-Ávila, Iván

    2014-01-01

    The diversity of deep-water corals in the Caribbean Sea was studied using records from oceanographic expeditions performed by the R/V Pillsbury. Sampled stations were sorted according to broad depth ranges and ecoregions and were analyzed in terms of species accumulation curves, variance in the species composition and contributions to alpha, beta and gamma diversity. According to the analysis of species accumulation curves using the Chao2 estimator, more diversity occurs on the continental slope (200–2000 m depth) than on the upper continental shelf (60–200 m depth). In addition to the effect of depth sampling, differences in species composition related to depth ranges were detected. However, the differences between ecoregions are dependent on depth ranges, there were fewer differences among ecoregions on the continental slope than on the upper continental shelf. Indicator species for distinctness of ecoregions were, in general, Alcyonaria and Antipatharia for the upper continental shelf, but also the scleractinians Madracis myriabilis and Cladocora debilis. In the continental slope, the alcyonarian Placogorgia and the scleractinians Stephanocyathus and Fungiacyathus were important for the distinction of ecoregions. Beta diversity was the most important component of gamma diversity in the Caribbean Basin. The contribution of ecoregions to alpha, beta and gamma diversity differed with depth range. On the upper continental shelf, the Southern Caribbean ecoregion contributed substantially to all components of diversity. In contrast, the northern ecoregions contributed substantially to the diversity of the Continental Slope. Strategies for the conservation of deep-water coral diversity in the Caribbean Basin must consider the variation between ecoregions and depth ranges. PMID:24671156

  18. Dynamics and mass accommodation of HCl molecules on sulfuric acid-water surfaces.

    PubMed

    Behr, P; Scharfenort, U; Ataya, K; Zellner, R

    2009-09-28

    A molecular beam technique has been used to study the dynamics and mass accommodation of HCl molecules in collision with sulfuric acid-water surfaces. The experiments were performed by directing a nearly mono-energetic beam of HCl molecules onto a continuously renewed liquid film of 54-76 wt% sulfuric acid at temperatures between 213 K and 243 K. Deuterated sulfuric acid was used to separate sticking but non-reactive collisions from those that involved penetration through the phase boundary followed by dissociation and recombination with D+. The results indicate that the mass accommodation of HCl on sulfuric acid-water surfaces decreases sharply with increasing acidity over the concentration range 54-76 wt%. Using the capillary wave theory of mass accommodation this effect is explained by a change of the surface dynamics. Regarding the temperature dependence it is found that the mass accommodation of HCl increases with increasing temperature and is limited by the bulk phase viscosity and driven by the restoring forces of the surface tension. These findings imply that under atmospheric conditions the uptake of HCl from the gas phase depends crucially on the bulk phase parameters of the sulfuric acid aerosol.

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

    PubMed

    Liu, Zhigang; Wang, Yong; Yedidi, Ravikiran S; Dewdney, Tamaria G; Reiter, Samuel J; Brunzelle, Joseph S; Kovari, Iulia A; Kovari, Ladislau C

    2013-01-18

    The 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. In addition, 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.

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

    SciTech Connect

    Liu, Zhigang; Wang, Yong; Yedidi, Ravikiran S.; Dewdney, Tamaria G.; Reiter, Samuel J.; Brunzelle, Joseph S.; Kovari, Iulia A.; Kovari, Ladislau C.

    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.

  1. A simple and efficient method to characterize bonded water molecules in aqueous solutions of electrolytes: Application to sodium sulphate decahydrate

    NASA Astrophysics Data System (ADS)

    Fargeot, Carole; Bebon, C.; Colson, D.; Klein, J.-P.; Blandin, A.-F.; Bossoutrot, J.-M.

    2007-09-01

    During a study on crystallization in viscous media, an unexpected relevant theoretical and experimental result about the organization of water molecules in salt solutions has been obtained. Experimental results obtained during measurement of viscosity of saccharose and water solutions demonstrate that the salt dissolved in saccharose solution has the capacity to catch the solvent, namely water, from the solvated substance, here saccharose, which induces a quite large viscosity gap. There is a certain mutual electrolyte-water attraction; it may be pushed on by stronger water-salt than water-saccharose interactions. Determination of the binding of water with the salt in the solution can be done directly from measured viscosity. The number of water molecules withdrawn by Na 2SO 4 in solution is computable from viscosity values. Significance of the results obtained is a relevant demonstration that the 10 water molecules of Na 2SO 4·10H 2O are already organised around the solute before the crystallization. The phenomenon observed here questions theoretical predictions that rely on solvent organization and salt effect in solution. Novelty of this study may thus encourage further experimental work in order to elucidate and test the validity of such investigational method to determine the number of water molecules withdrawn by salt in solution.

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

    PubMed

    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.

  3. The binding energies of one and two water molecules to the first transition-row metal positive ions. II

    NASA Technical Reports Server (NTRS)

    Rosi, Marzio; Bauschlicher, Charles W., Jr.

    1990-01-01

    The present investigation of H2O's binding energy to transition-metal ions proceeds from the D(2h) structure and bends the two water molecules out of plane. The molecule is constrained to have C(2v) symmetry, so that each water molecule and metal ion lies on a plane. The ground states are bent only for Mn(H2O)2(+) and Zn(H2O)2(+), where only 4s4p hybridization is energetically favorable; 4s4p hybridization reduces repulsion.

  4. On the reactive uptake of gaseous PAH molecules by micron-sized atmospheric water droplets

    NASA Astrophysics Data System (ADS)

    Raja, S.; Valsaraj, K. T.

    2006-10-01

    A falling droplet reactor was used to study the heterogeneous oxidation of gaseous PAH molecules adsorbed on a 92 μm diameter water droplet by ozone. The dynamic partition constant for the PAH between the droplet and air and the first-order surface rate constant was measured. The increase in uptake with ozone concentration was due to increased mass transfer via surface reaction of co-adsorbed ozone and PAH. The surface rate constant was rationalized through the Langmuir-Hinshelwood mechanism. The rate constant was smaller for phenanthrene than naphthalene. The main reaction products identified in the aqueous phase indicated the peroxidic route for surface reaction of ozone with PAH. The heterogeneous reaction rate of ozone with adsorbed phenanthrene at the air-water interface of a 92-μm droplet was estimated to be 9300 times larger than the homogeneous reaction of ozone with phenanthrene in the gas phase and it was 76 times larger than the homogeneous oxidation by hydroxyl radical in the gas phase. For naphthalene that is more volatile, however, the homogeneous reaction with hydroxyl was more important. Increased organic carbon added to the droplet increased both the partition constant for phenanthrene and surface reaction with ozone. The partition constant for a droplet formed from actual fog water was much larger than for pure distilled water.

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

    PubMed

    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.

  6. Cation effects on rotational dynamics of anions and water molecules in alkali (Li+, Na+, K+, Cs+) thiocyanate (SCN-) aqueous solutions.

    PubMed

    Bian, Hongtao; Chen, Hailong; Zhang, Qiang; Li, Jiebo; Wen, Xiewen; Zhuang, Wei; Zheng, Junrong

    2013-07-03

    Waiting time dependent rotational anisotropies of SCN(-) anions and water molecules in alkali thiocyanate (XSCN, X = Li, Na, K, Cs) aqueous solutions at various concentrations were measured with ultrafast infrared spectroscopy. It was found that cations can significantly affect the reorientational motions of both water molecules and SCN(-) anions. The dynamics are slower in a solution with a smaller cation. The reorientational time constants follow the order of Li(+) > Na(+) > K(+) ~/= Cs(+). The changes of rotational time constants of SCN(-) at various concentrations scale almost linearly with the changes of solution viscosity, but those of water molecules do not. In addition, the concentration-dependent amplitudes of dynamical changes are much more significant in the Li(+) and Na(+) solutions than those in the K(+) and Cs(+) solutions. Further investigations on the systems with the ultrafast vibrational energy exchange method and molecular dynamics simulations provide an explanation for the observations: the observed rotational dynamics are the balanced results of ion clustering and cation/anion/water direct interactions. In all the solutions at high concentrations (>5 M), substantial amounts of ions form clusters. The structural inhomogeneity in the solutions leads to distinct rotational dynamics of water and anions. The strong interactions of Li(+) and Na(+) because of their relatively large charge densities with water molecules and SCN(-) anions, in addition to the likely geometric confinements because of ion clustering, substantially slow down the rotations of SCN(-) anions and water molecules inside the ion clusters. The interactions of K(+) and Cs(+) with water or SCN(-) are much weaker. The rotations of water molecules inside ion clusters of K(+) and Cs(+) solutions are not significantly different from those of other water species so that the experimentally observed rotational relaxation dynamics are only slightly affected by the ion concentrations.

  7. Effects of water molecules on rearrangements of formamide on the kaolinite basal (001) surface.

    PubMed

    Nguyen, Huyen Thi; Nguyen, Minh Tho

    2014-08-28

    The effects of kaolinite mineral surfaces on the unimolecular rearrangements of formamide (FM) were investigated using periodic density functional theory in conjunction with pseudopotential plane-wave approach. Surface hydroxyl groups covering the octahedral surface of kaolinite were found to play the role of catalysts in the transformations of FM. They induce a reduction of 31 kcal/mol on the energy barrier for formation of its isomer aminohydroxymethylene (AHM), which is close to the reduction amount calculated for water-catalyzed reactions. This suggests that the kaolinite octahedral surface exerts a catalytic effect similar to that of the water molecule. As the tetrahedral surface does not contain catalytic surface hydroxyl groups, only water-assisted FM transformation was therefore studied on this surface whose energy barrier amounts to ∼17 kcal/mol. The combined effect of both water and kaolinite on FM rearrangements via triple hydrogen transfer reactions does not significantly lower the energy barriers, as compared to those of double hydrogen transfer reactions. The triple hydrogen transfer energy barriers amount to ∼20 and ∼36 kcal/mol, and the double ones are ∼21 and ∼40 kcal/mol for formation of formimic acid and AHM isomers, respectively. However, the energies of the systems in water-catalyzed channels lie below the available energies of the original reactants, and thus these channels are more favored than the water-free ones. With its multiple functions as both a supporting plate-form and a catalyst for FM reactions, kaolinite can thus be regarded as an important natural catalyst for prebiotic synthesis.

  8. Unintended consequences? Water molecules at biological and crystallographic protein-protein interfaces.

    PubMed

    Ahmed, Mostafa H; Habtemariam, Mesay; Safo, Martin K; Scarsdale, J Neel; Spyrakis, Francesca; Cozzini, Pietro; Mozzarelli, Andrea; Kellogg, Glen E

    2013-12-01

    The importance of protein-protein interactions (PPIs) is becoming increasingly appreciated, as these interactions lie at the core of virtually every biological process. Small molecule modulators that target PPIs are under exploration as new therapies. One of the greatest obstacles faced in crystallographically determining the 3D structures of proteins is coaxing the proteins to form "artificial" PPIs that lead to uniform crystals suitable for X-ray diffraction. This work compares interactions formed naturally, i.e., "biological", with those artificially formed under crystallization conditions or "non-biological". In particular, a detailed analysis of water molecules at the interfaces of high-resolution (≤2.30 Å) X-ray crystal structures of protein-protein complexes, where 140 are biological protein-protein complex structures and 112 include non-biological protein-protein interfaces, was carried out using modeling tools based on the HINT forcefield. Surprisingly few and relatively subtle differences were observed between the two types of interfaces: (i) non-biological interfaces are more polar than biological interfaces, yet there is better organized hydrogen bonding at the latter; (ii) biological associations rely more on water-mediated interactions with backbone atoms compared to non-biological associations; (iii) aromatic/planar residues play a larger role in biological associations with respect to water, and (iv) Lys has a particularly large role at non-biological interfaces. A support vector machines (SVMs) classifier using descriptors from this study was devised that was able to correctly classify 84% of the two interface types.

  9. Water solvent effects using continuum and discrete models: The nitromethane molecule, CH3NO2.

    PubMed

    Modesto-Costa, Lucas; Uhl, Elmar; Borges, Itamar

    2015-11-15

    The first three valence transitions of the two nitromethane conformers (CH3NO2) are two dark n → π* transitions and a very intense π → π* transition. In this work, these transitions in gas-phase and solvated in water of both conformers were investigated theoretically. The polarizable continuum model (PCM), two conductor-like screening (COSMO) models, and the discrete sequential quantum mechanics/molecular mechanics (S-QM/MM) method were used to describe the solvation effect on the electronic spectra. Time dependent density functional theory (TDDFT), configuration interaction including all single substitutions and perturbed double excitations (CIS(D)), the symmetry-adapted-cluster CI (SAC-CI), the multistate complete active space second order perturbation theory (CASPT2), and the algebraic-diagrammatic construction (ADC(2)) electronic structure methods were used. Gas-phase CASPT2, SAC-CI, and ADC(2) results are in very good agreement with published experimental and theoretical spectra. Among the continuum models, PCM combined either with CASPT2, SAC-CI, or B3LYP provided good agreement with available experimental data. COSMO combined with ADC(2) described the overall trends of the transition energy shifts. The effect of increasing the number of explicit water molecules in the S-QM/MM approach was discussed and the formation of hydrogen bonds was clearly established. By including explicitly 24 water molecules corresponding to the complete first solvation shell in the S-QM/MM approach, the ADC(2) method gives more accurate results as compared to the TDDFT approach and with similar computational demands. The ADC(2) with S-QM/MM model is, therefore, the best compromise for accurate solvent calculations in a polar environment.

  10. ORGANIC MOLECULES AND WATER IN THE INNER DISKS OF T TAURI STARS

    SciTech Connect

    Carr, John S.; Najita, Joan R. E-mail: najita@noao.edu

    2011-06-01

    We report high signal-to-noise Spitzer Infrared Spectrograph spectra of a sample of 11 classical T Tauri stars. Molecular emission from rotational transitions of H{sub 2}O and OH and rovibrational bands of simple organic molecules (CO{sub 2}, HCN, C{sub 2}H{sub 2}) is common among the sources in the sample. The emission shows a range in both flux and line-to-continuum ratio for each molecule and in the flux ratios of different molecular species. The gas temperatures (200-800 K) and emitting areas we derive are consistent with the emission originating in a warm disk atmosphere in the inner planet formation region at radii <2 AU. The H{sub 2}O emission appears to form under a limited range of excitation conditions, as demonstrated by the similarity in relative strengths of H{sub 2}O features from star to star and the narrow range in derived temperature and column density. Emission from highly excited rotational levels of OH is present in all stars; the OH emission flux increases with the stellar accretion rate, and the OH/H{sub 2}O flux ratio shows a relatively small scatter. We interpret these results as evidence for OH production via FUV photodissociation of H{sub 2}O in the disk surface layers. No obvious explanation is found for the observed range in the relative emission strengths of different organic molecules or in their strength with respect to water. We put forward the possibility that these variations reflect a diversity in organic abundances due to star-to-star differences in the C/O ratio of the inner disk gas. Stars with the largest HCN/H{sub 2}O flux ratios in our sample have the largest disk masses. While larger samples are required to confirm this, we speculate that such a trend could result if higher mass disks are more efficient at planetesimal formation and sequestration of water in the outer disk, leading to enhanced C/O ratios and abundances of organic molecules in the inner disk. A comparison of our derived HCN-to-H{sub 2}O column density ratio

  11. Pseudorhabdosynochus species (Monogenoidea, Diplectanidae) parasitizing groupers (Serranidae, Epinephelinae, Epinephelini) in the western Atlantic Ocean and adjacent waters, with descriptions of 13 new species.

    PubMed

    Kritsky, Delane C; Bakenhaster, Micah D; Adams, Douglas H

    2015-01-01

    Seventeen of twenty-three species of groupers collected from the western Atlantic Ocean and adjacent waters were infected with 19 identified species (13 new) of Pseudorhabdosynochus Yamaguti, 1958 (Dactylogyridea, Diplectanidae); specimens of the Spanish flag Gonioplectrus hispanus, coney Cephalopholis fulva, marbled grouper Dermatolepis inermis, mutton hamlet Alphestes afer, and misty grouper Hyporthodus mystacinus were not infected; the yellowmouth grouper Mycteroperca interstitialis and yellowfin grouper Mycteroperca venenosa were infected with unidentified species of Pseudorhabdosynochus; the Atlantic creolefish Paranthias furcifer was infected with an unidentified species of Diplectanidae that could not be accommodated in Pseudorhabdosynochus. The following species of Pseudorhabdosynochus are described or redescribed based entirely or in part on new collections: Pseudorhabdosynochus americanus (Price, 1937) Kritsky & Beverley-Burton, 1986 from Atlantic goliath grouper Epinephelus itajara; Pseudorhabdosynochus yucatanensis Vidal-Martínez, Aguirre-Macedo & Mendoza-Franco, 1997 and Pseudorhabdosynochus justinella n. sp. from red grouper Epinephelus morio; Pseudorhabdosynochus kritskyi Dyer, Williams & Bunkley-Williams, 1995 from gag Mycteroperca microlepis; Pseudorhabdosynochus capurroi Vidal-Martínez & Mendoza-Franco, 1998 from black grouper Mycteroperca bonaci; Pseudorhabdosynochus hyphessometochus n. sp. from Mycteroperca interstitialis; Pseudorhabdosynochus sulamericanus Santos, Buchmann & Gibson, 2000 from snowy grouper Hyporthodus niveatus and Warsaw grouper Hyporthodus nigritus (new host record); Pseudorhabdosynochus firmicoleatus n. sp. from yellowedge grouper Hyporthodus flavolimbatus and snowy grouper H. niveatus; Pseudorhabdosynochus mcmichaeli n. sp., Pseudorhabdosynochus contubernalis n. sp., and Pseudorhabdosynochus vascellum n. sp. from scamp Mycteroperca phenax; Pseudorhabdosynochus meganmarieae n. sp. from graysby Cephalopholis cruentata

  12. Pseudorhabdosynochus species (Monogenoidea, Diplectanidae) parasitizing groupers (Serranidae, Epinephelinae, Epinephelini) in the western Atlantic Ocean and adjacent waters, with descriptions of 13 new species

    PubMed Central

    Kritsky, Delane C.; Bakenhaster, Micah D.; Adams, Douglas H.

    2015-01-01

    Seventeen of twenty-three species of groupers collected from the western Atlantic Ocean and adjacent waters were infected with 19 identified species (13 new) of Pseudorhabdosynochus Yamaguti, 1958 (Dactylogyridea, Diplectanidae); specimens of the Spanish flag Gonioplectrus hispanus, coney Cephalopholis fulva, marbled grouper Dermatolepis inermis, mutton hamlet Alphestes afer, and misty grouper Hyporthodus mystacinus were not infected; the yellowmouth grouper Mycteroperca interstitialis and yellowfin grouper Mycteroperca venenosa were infected with unidentified species of Pseudorhabdosynochus; the Atlantic creolefish Paranthias furcifer was infected with an unidentified species of Diplectanidae that could not be accommodated in Pseudorhabdosynochus. The following species of Pseudorhabdosynochus are described or redescribed based entirely or in part on new collections: Pseudorhabdosynochus americanus (Price, 1937) Kritsky & Beverley-Burton, 1986 from Atlantic goliath grouper Epinephelus itajara; Pseudorhabdosynochus yucatanensis Vidal-Martínez, Aguirre-Macedo & Mendoza-Franco, 1997 and Pseudorhabdosynochus justinella n. sp. from red grouper Epinephelus morio; Pseudorhabdosynochus kritskyi Dyer, Williams & Bunkley-Williams, 1995 from gag Mycteroperca microlepis; Pseudorhabdosynochus capurroi Vidal-Martínez & Mendoza-Franco, 1998 from black grouper Mycteroperca bonaci; Pseudorhabdosynochus hyphessometochus n. sp. from Mycteroperca interstitialis; Pseudorhabdosynochus sulamericanus Santos, Buchmann & Gibson, 2000 from snowy grouper Hyporthodus niveatus and Warsaw grouper Hyporthodus nigritus (new host record); Pseudorhabdosynochus firmicoleatus n. sp. from yellowedge grouper Hyporthodus flavolimbatus and snowy grouper H. niveatus; Pseudorhabdosynochus mcmichaeli n. sp., Pseudorhabdosynochus contubernalis n. sp., and Pseudorhabdosynochus vascellum n. sp. from scamp Mycteroperca phenax; Pseudorhabdosynochus meganmarieae n. sp. from graysby Cephalopholis cruentata

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

    PubMed

    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. Investigations of the Structure and Hydrogen Bonding of Water Molecules at Liquid Surfaces by Vibrational Sum Frequency Spectroscopy

    DTIC Science & Technology

    1998-06-01

    studies conducted for the first time at liquid surfaces are also described. In these studies the intermolecular and intramolecular coupling of vibrational ... modes in the water molecules are diminished. The results of these and above mentioned studies provide valuable information for those interested in developing theoretical descriptions of water at surfaces and interfaces.

  15. Rotations and vibrations of water molecule inside the fullerene cage: infrared study of H2O@C60

    NASA Astrophysics Data System (ADS)

    Room, Toomas; Shugai, A.; Nagel, U.; Mamone, S.; Krachmalnicoff, A.; Whitby, R. J.; Levitt, M. H.; Nishida, T.; Murata, Y.; Lei, Xuegong; Li, Yongjun; Turro, N. J.

    2015-03-01

    Water is the second molecule after hydrogen what has been trapped inside the cage of a C60 molecule by the molucular surgery method. We studied isolated water molecule isotopologs H2O, D2O, and HDO in the solid phase at cryogenic temperatures using IR spectroscopy. The water molecule rotation transitions were observed in the THz and vibration-rotation transitions in the mid-IR range. The slow conversion between para and ortho water allowed us to record the time evolution of spectra and to separate ortho and para absorption lines of water. The similarity of the rotation spectrum of caged water to water in the gas phase indicates that water is free to rotate in the C60 cage even at temperature as low as 3 K. However, spectral lines show a splitting of about 0.5 meV what is not compatible with the icosahedral symmetry of C60. Different models (e.g. crystal field effects in solid C60, C60 cage distortions) will be discussed. This work was supported by institutional research funding IUT23-3 of the Estonian Ministry of Education and Research.

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

    PubMed

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

    2014-06-21

    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.

  17. Adsorption of apolar molecules at the water liquid-vapor interface: A Monte Carlo simulations study of the water-n-octane system

    NASA Astrophysics Data System (ADS)

    Jedlovszky, Pál; Varga, Imre; Gilányi, Tibor

    2003-07-01

    The adsorption of n-octane at the water liquid-vapor interface has been investigated by Monte Carlo computer simulation. For this purpose, simulation of five different water-apolar interfacial systems have been performed, in which the number of n-octane molecules has been varied. The results clearly show that the apolar n-octane molecules are adsorbed from the vapor phase at the interface. The adsorption is driven by the weak attraction due to the dispersion forces acting between the water molecules and the methyl and methylene groups of the octanes. This weak attraction is, however, amplified by the fact that it is added up for the CH2 and CH3 groups belonging to the same molecule. Consistently, the n-octane molecules located closest to the aqueous phase are found to prefer all-trans conformation and parallel alignment with the plane of the interface. On the other hand, entropic effects become more important among the molecules of the outer part of the adsorption layer. Hence, the preferred orientation of these molecules is perpendicular to the interface, as they can be extended toward the less dense region of the apolar phase; and gauche dihedrals appear more frequently here than among the molecules located next to the aqueous phase.

  18. Calculations for ion-impact induced ionization and fragmentation of water molecules

    NASA Astrophysics Data System (ADS)

    Kirchner, Tom; Murakami, Mitsuko; Horbatsch, Marko; Jürgen Lüdde, Hans

    2012-10-01

    Charge-state correlated cross sections for single- and multiple-electron removal processes in proton-water-molecule collisions are calculated by using the non-perturbative basis generator method adapted for ion-molecule collisions [1,2]. A fragmentation model is then applied to calculate the yields of H2O^+, OH^+, H^+, and O^+ ions emerging after H2O^q+ formation [3]. A detailed comparison is made with experimental data from three groups covering the energy range from 20--5000 keV. It is found that multiple electron processes with q<=3 play an important role at the lower end of this range and are calculated accurately within an independent particle model. We are currently completing the analogous analysis for He^+-H2O collisions for which the presence of the projectile electron poses some additional challenges. [4pt] [1] H.J. L"udde et al, Phys. Rev. A 80, 060702(R) (2009)[0pt] [2] M. Murakami et al, Phys. Rev. A 85, 052704 (2012)[0pt] [3] M. Murakami et al, Phys. Rev. A 85, 052713 (2012)

  19. Rate-Enhancing Roles of Water Molecules in Methyltrioxorhenium-Catalyzed Olefin Epoxidation by Hydrogen Peroxide.

    PubMed

    Goldsmith, Bryan R; Hwang, Taeho; Seritan, Stefan; Peters, Baron; Scott, Susannah L

    2015-08-05

    Olefin epoxidation catalyzed by methyltrioxorhenium (MTO, CH3ReO3) is strongly accelerated in the presence of H2O. The participation of H2O in each of the elementary steps of the catalytic cycle, involving the formation of the peroxo complexes (CH3ReO2(η(2)-O2), A, and CH3ReO(η(2)-O2)2(H2O), B), as well as in their subsequent epoxidation of cyclohexene, was examined in aqueous acetonitrile. Experimental measurements demonstrate that the epoxidation steps exhibit only weak [H2O] dependence, attributed by DFT calculations to hydrogen bonding between uncoordinated H2O and a peroxo ligand. The primary cause of the observed H2O acceleration is the strong co-catalytic effect of water on the rates at which A and B are regenerated and consequently on the relative abundances of the three interconverting Re-containing species at steady state. Proton transfer from weakly coordinated H2O2 to the oxo ligands of MTO and A, resulting in peroxo complex formation, is directly mediated by solvent H2O molecules. Computed activation parameters and kinetic isotope effects, in combination with proton-inventory experiments, suggest a proton shuttle involving one or (most favorably) two H2O molecules in the key ligand-exchange steps to form A and B from MTO and A, respectively.

  20. Diffusion of small molecules in a chitosan/water gel determined by proton localized NMR spectroscopy.

    PubMed

    García-Aparicio, Carlos; Quijada-Garrido, Isabel; Garrido, Leoncio

    2012-02-15

    Proton localized NMR spectroscopy (MRS) has been applied to study the diffusion of three small molecules, caffeine, theophylline and caprolactam, in chitosan gels with different concentration of water. This technique allows the non-destructive monitorization of diffusant concentration as a function of time and location. Concentration profiles were compared with theoretical curves based on solutions of Fick's diffusion equation for the best fitting, with the appropriate boundary conditions. The measured concentration profiles show a good agreement with the Fickian law. Values of the diffusion coefficients D ranging from 6.1×10(-6) to 3.4×10(-6)cm(2)s(-1) depending on chitosan concentration and type of diffusant molecule were determined. In addition, measurements of diffusion coefficients at equilibrium conditions with proton pulsed field gradient NMR methods supported the observed Fickian behavior and showed values of D in excellent agreement with those determined by proton MRS. All these facts demonstrate that proton MRS is an appropriate method for investigating diffusion process in complex systems, such as polymer gels.

  1. New approximate orientation averaging of the water molecule interacting with the thermal neutron

    SciTech Connect

    Markovic, M.I.; Minic, D.M.; Rakic, A.D. . Elektrotehnicki Fakultet)

    1992-02-01

    This paper reports that exactly describing the time of thermal neutron collisions with water molecules, orientation averaging is performed by an exact method (EOA{sub k}) and four approximate methods (two well known and two less known). Expressions for the microscopic scattering kernel are developed. The two well-known approximate orientation averaging methods are Krieger-Nelkin (K-N) and Koppel-Young (K-Y). The results obtained by one of the two proposed approximate orientation averaging methods agree best with the corresponding results obtained by EOA{sub k}. The largest discrepancies between the EOA{sub k} results and the results of the approximate methods are obtained using the well-know K-N approximate orientation averaging method.

  2. Three-body neutral dissociations of a multiply excited water molecule around the double ionization potential

    NASA Astrophysics Data System (ADS)

    Odagiri, Takeshi; Nakano, Motoyoshi; Tanabe, Takehiko; Kumagai, Yoshiaki; Suzuki, Isao H.; Kitajima, Masashi; Kouchi, Noriyuki

    2012-11-01

    The cross sections for emission of two fluorescence photons from a pair of excited fragments in photoexcitation of H2O have been measured as a function of the incident photon energy using the photon-photon coincidence technique. The cross section increased in the range 30-45 eV, i.e. in the vicinity of the double ionization potential of H2O. The increase of the cross section was attributed to three-body neutral dissociations of a water molecule via multiply excited states: H2O** → H(2p) + OH** → H(2p) + H(2p) + O(3P). Some multiply excited states of H2O were also found in the cross section curve around 65 eV.

  3. Vibrational-excitation cross sections of water molecules by electron impact

    NASA Technical Reports Server (NTRS)

    Shyn, T. W.; Cho, S. Y.; Cravens, T. E.

    1988-01-01

    A crossed-beam technique was used to measure absolute differential cross sections for the vibrational excitation of water-vapor molecules. The energy and angular range were from 2.2 to 20 eV and from 30 to 150 deg. Vibrational-excitation cross sections were determined for the bending (010) and stretching (100 and 001) modes of the electronic ground state. It is shown that the integral cross sections are generally larger than those of Seng and Linder (1976) by 10-20 percent for both the bending and stretching modes. It is noted that the results obtained are of interest in connection with the theoretical modeling of cometary ionospheres.

  4. Thermochemical properties of the ammonia-water ionized dimer probed by ion-molecule reactions.

    PubMed

    Abdel Azeim, Safwat; van der Rest, Guillaume

    2005-03-24

    The thermochemical properties of some small clusters such as the (H2O)2*+ dimer have already been investigated by both experimental and theoretical methods. The recent method to selectively prepare the ammonia-water ionized dimer [NH3, H2O]*+ (and not its proton transfer isomer [NH4+, OH*]) allowed us to study its chemical reactivity. This study focuses on the charge and proton transfer pathways: Ion-molecule reactions in the cell of an FT-ICR mass spectrometer were carried out with a range of organic compounds. Examination of the reactivity of the [NH3, H2O]*+ ionized dimer versus ionization energy and proton affinity of the neutral reagents shows a threshold in the reactivity in both instances. This leads to a bracketing of thermochemical properties related to the dimer. From these experiments and in agreement with ab initio calculations, the adiabatic recombination energy of the [NH3, H2O]*+ dimer was evaluated at -9.38 +/- 0.04 eV. The proton affinity bracketing required the reevaluation of two reference gas-phase basicity values. The results, in good agreement with the calculation, lead to an evaluation of the proton affinity of the [NH2*, H2O] dimer at 204.4 +/- 0.9 kcal mol(-1). These two experimental values are respectively related to the ionization energy of NH3*+ and to the proton affinity of NH2* by the difference in single water molecule solvation energies of ionized ammonia, of neutral ammonia, and of the NH2* radical.

  5. Design, revision, and application of ground-water flow models for simulation of selected water-management scenarios in the coastal area of Georgia and adjacent parts of South Carolina and Florida

    USGS Publications Warehouse

    Clarke, John S.; Krause, Richard E.

    2000-01-01

    Ground-water flow models of the Floridan aquifer system in the coastal area of Georgia and adjacent parts of South Carolina and Florida, were revised and updated to ensure consistency among the various models used, and to facilitate evaluation of the effects of pumping on the ground-water level near areas of saltwater contamination. The revised models, developed as part of regional and areal assessments of ground-water resources in coastal Georgia, are--the Regional Aquifer-System Analysis (RASA) model, the Glynn County area (Glynn) model, and the Savannah area (Savannah) model. Changes were made to hydraulic-property arrays of the RASA and Glynn models to ensure consistency among all of the models; results of theses changes are evidenced in revised water budgets and calibration statistics. Following revision, the three models were used to simulate 32 scenarios of hypothetical changes in pumpage that ranged from about 82 million gallons per day (Mgal/d) lower to about 438 Mgal/d higher, than the May 1985 pumping rate of 308 Mgal/d. The scenarios were developed by the Georgia Department of Natural Resources, Environmental Protection Division and the Chatham County-Savannah Metropolitan Planning Commission to evaluate water-management alternatives in coastal Georgia. Maps showing simulated ground-water-level decline and diagrams presenting changes in simulated flow rates are presented for each scenario. Scenarios were grouped on the basis of pumping location--entire 24-county area, central subarea, Glynn-Wayne-Camden County subarea, and Savannah-Hilton Head Island subarea. For those scenarios that simulated decreased pumpage, the water level at both Brunswick and Hilton Head Island rose, decreasing the hydraulic gradient and reducing the potential for saltwater contamination. Conversely, in response to scenarios of increased pumpage, the water level at both locations declined, increasing the hydraulic gradient and increasing the potential for saltwater contamination

  6. Single Molecule Lateral Mobility and Membrane Organization in DMPC/Cholesterol Mixtures at the Air-Water Interface

    NASA Astrophysics Data System (ADS)

    Shaikh, Saame; Stillwell, William; Naumann, Christoph

    2002-03-01

    To better understand the lipid heterogeneity of biological membranes, we have studied the lateral mobility and membrane organization of DMPC and cholesterol (Chol) mixtures at the air-water interface using single molecule fluorescence imaging and epifluorescence microscopy. The single molecule imaging technique was used to track the lateral diffusion of single molecules of TRITC-DPPE or cholesteryl Bodipy. In the absence of Chol, mean square displacement histograms obtained from single molecule tracking of TRITC-DPPE show unobstructed diffusion. Including Chol at low levels of Chol (<10 moldiffusion at intermediate levels ( 30 molof Chol (>40 molmacroscopic phase separations. Data obtained from tracking experiments of cholesteryl-Bodipy also show complementary changes in diffusion. Our results indicate that our techniques provide insight into the micro and macro organization of lipid domains at the air-water interface.

  7. Measurements of the number density of water molecules in plasma by using a combined spectral-probe method

    NASA Astrophysics Data System (ADS)

    Bernatskiy, A. V.; Ochkin, V. N.; Afonin, O. N.; Antipenkov, A. B.

    2015-09-01

    A novel method for measuring the number density of water molecules in low-temperature plasma is developed. The absolute intensities of rotational lines of the (0,0) band of the OH( A 2Σ- X 2П) transition are used. Lines with sufficiently large rotational quantum numbers referring to the so-called "hot" group of molecules produced by electron-impact dissociative excitation of water molecules are chosen for measurements. The excitation rate of a process with a known cross section is determined by measuring the parameters of plasma electrons by means of the probe method. The measured number densities of molecules are compared with those in the initial plasma-forming mixture. The time evolution of the particle densities in plasma is investigated. The problems of the sensitivity and applicability of the absolute spectral method are considered.

  8. Response to Memorandum by Rowley and Dixon Regarding U.S. Geological Survey Report Titled "Characterization of Surface-Water Resources in the Great Basin National Park Area and Their Susceptibility to Ground-Water Withdrawals in Adjacent Valleys, White Pine County, Nevada"

    DTIC Science & Technology

    2006-01-01

    mountains to evaluate effects caused by ground- water pumping in adjacent valleys. 7 Rowley and Dixon failed to recognize when they stated “Seepage tests...measurements: U.S. Geological Survey Open-File Report 92–144, 21 p. Sophocleous, Marious, 2000, From safe yield to sustainable development of water ...surface- water and ground- water quality , southern San Mateo and northern Santa Clara counties, California, 1996–97: U.S. Geological Survey Water -Resources

  9. Encapsulation and Residency of a Hydrophobic Dye within the Water-Filled Interior of a PAMAM Dendrimer Molecule.

    PubMed

    Koley, Somnath; Ghosh, Subhadip

    2017-03-02

    Tightly confined water within a small droplet behaves differently from bulk water. This notion is obtained on the basis of several reports showing unusual behaviors of water droplet residing at the core of a reverse micelle. In this study, we have shown a well-known hydrophobic dye, coumarin 153 (C153), which prefers to reside at the water-rich region inside the dendrimer molecule. Optical density (OD) measurement at the absorption peak of C153 shows that it is almost insoluble in bulk water but highly soluble in aqueous dendrimer solution. The OD of C153 increases several times in the latter case as compared to that in the former. We found the most interesting observation when we compared the data from fluorescence correlation spectroscopy (FCS) with the fluorescence anisotropy decay of C153 in aqueous dendrimer solution. The FCS measurement reveals a much slower translational diffusion time (τD) of C153 attached to a dendrimer molecule as compared to that of free C153 in bulk water in the absence of dendrimer. The slower τD in the former case is commensurate with the size of the dendrimer molecule. This is possible only when C153 is encapsulated by the dendrimer molecule. In contrast to the FCS study, the fluorescence anisotropy decay of C153 in water remains largely invariant after addition of the dendrimer. This can happen if a bulk-water-like environment at the C153 surroundings is preserved within the C153-dendrimer complex. This supports our institutive expectation that C153 resides within the water-rich peripheral cavities of the dendrimer molecule. A more expected binding of C153 to the hydrophobic core of dendrimer may not be possible here because of an inadequate size of the dendrimer core.

  10. A proactive role of water molecules in acceptor recognition by protein O-fucosyltransferase 2.

    PubMed

    Valero-González, Jessika; Leonhard-Melief, Christina; Lira-Navarrete, Erandi; Jiménez-Osés, Gonzalo; Hernández-Ruiz, Cristina; Pallarés, María Carmen; Yruela, Inmaculada; Vasudevan, Deepika; Lostao, Anabel; Corzana, Francisco; Takeuchi, Hideyuki; Haltiwanger, Robert S; Hurtado-Guerrero, Ramon

    2016-04-01

    Protein O-fucosyltransferase 2 (POFUT2) is an essential enzyme that fucosylates serine and threonine residues of folded thrombospondin type 1 repeats (TSRs). To date, the mechanism by which this enzyme recognizes very dissimilar TSRs has been unclear. By engineering a fusion protein, we report the crystal structure of Caenorhabditis elegans POFUT2 (CePOFUT2) in complex with GDP and human TSR1 that suggests an inverting mechanism for fucose transfer assisted by a catalytic base and shows that nearly half of the TSR1 is embraced by CePOFUT2. A small number of direct interactions and a large network of water molecules maintain the complex. Site-directed mutagenesis demonstrates that POFUT2 fucosylates threonine preferentially over serine and relies on folded TSRs containing the minimal consensus sequence C-X-X-S/T-C. Crystallographic and mutagenesis data, together with atomic-level simulations, uncover a binding mechanism by which POFUT2 promiscuously recognizes the structural fingerprint of poorly homologous TSRs through a dynamic network of water-mediated interactions.

  11. Small molecule, big difference: the role of water in the crystallization of paclitaxel.

    PubMed

    Vella-Zarb, Liana; Baisch, Ulrich; Dinnebier, Robert E

    2013-02-01

    Paclitaxel is an important antineoplastic drug, which is used widely in the treatment of many forms of cancer. The crystal structures of the anhydrous form and the hemihydrate were determined from laboratory X-ray powder diffraction data, whereas the dihydrate was solved from single-crystal synchrotron diffraction data. Intermolecular spaces allow for the inclusion of loosely bound water molecules, which are then lost easily upon heating. All three forms were found to crystallize in the orthorhombic spacegroup P2(1)2(1)2(1), with Z' = 2. The unit cell parameters were found to be a = 9.6530(3) Å, b = 28.1196(8) Å, c = 33.5378(14) Å, and V = 9103.5(5) Å for the anhydrous form (363 K); a = 9.6890(2) Å, b = 28.0760(4) Å, c = 33.6166(8) Å, and V = 9144.7(3) Å(3) for the hemihydrate (333 K); and a = 9.512(6) Å, b = 28.064(16) Å, c = 33.08(2) Å, and V = 8829.0(9) Å(3) for the dihydrate (120 K). Water loss occurs in two steps between 120 K ≤ t ≤ 363 K. The thermal stability of the hydrates and accompanying unit cell changes were observed in situ via temperature-resolved X-ray powder diffraction and thermogravimetric analysis.

  12. A proactive role of water molecules in acceptor recognition by Protein-O-fucosyltransferase 2

    PubMed Central

    Valero-González, Jessika; Leonhard-Melief, Christina; Lira-Navarrete, Erandi; Jiménez-Osés, Gonzalo; Hernández-Ruiz, Cristina; Pallarés, María Carmen; Yruela, Inmaculada; Vasudevan, Deepika; Lostao, Anabel; Corzana, Francisco; Takeuchi, Hideyuki; Haltiwanger, Robert S.; Hurtado-Guerrero, Ramon

    2016-01-01

    Protein O-fucosyltransferase 2 (POFUT2) is an essential enzyme that fucosylates serine/threonine residues of folded thrombospondin type 1 repeats (TSRs). To date, the mechanism by which this enzyme recognizes very dissimilar TSRs remained unclear. By engineering of a fusion protein, we report the crystal structure of Caenorhabditis elegans POFUT2 (CePOFUT2) in complex with GDP and human TSR1 that suggests an inverting mechanism for fucose transfer assisted by a catalytic base, and shows that nearly half of the TSR1 is embraced by CePOFUT2. A small number of direct interactions and a large network of water molecules maintain the complex. Site-directed mutagenesis demonstrates that POFUT2 fucosylates threonine preferentially over serine and relies on folded TSRs containing the minimal consensus sequence CXX(S/T)C. Crystallographic and mutagenesis data together with atomic-level simulations uncover an unprecedented binding mechanism by which POFUT2 promiscuously recognizes the structural fingerprint of poorly homologous TSRs through a dynamic network of water-mediated interactions. PMID:26854667

  13. Lattice water molecules tuned spin-crossover for an iron(II) complex with thermal hysteresis.

    PubMed

    Luo, Yang-Hui; Yang, Li-Jing; Liu, Qing-Ling; Ling, Yang; Wang, Wei; Sun, Bai-Wang

    2014-11-28

    A new iron(II) complex based on the 4,4'-dimethyl-2,2'-bipyridine ligand [Fe(4,4'-dmbpy)3(ClO4)(SCN)·3H2O (1·3H2O)] has been prepared and characterized. Structural studies and Hirshfeld surface analysis for complex 1·3H2O at three different temperatures (300, 240 and 130 K) are described. The UV-vis absorption spectrum of a water-free sample (1) in methanol solution and magnetic susceptibility measurements for solid-state samples 1·3H2O and 1 revealed that the removal of lattice water molecules from complex 1·3H2O changed the magnetic properties from the low-spin state (1·3H2O) to the complete spin-crossover (1) between 350-220 K with a thermal hysteresis of 7 K, and was accompanied by a colour change from brown to red.

  14. Application of inhomogeneous fluid solvation theory to model the distribution and thermodynamics of water molecules around biomolecules.

    PubMed

    Huggins, David J

    2012-11-21

    The structures of biomolecules and the strengths of association between them depend critically on interactions with water molecules. Thus, understanding these interactions is a prerequisite for understanding the structure and function of all biomolecules. Inhomogeneous fluid solvation theory provides a framework to derive thermodynamic properties of individual water molecules from a statistical mechanical analysis. In this work, two biomolecules are analysed to probe the distribution and thermodynamics of surrounding water molecules. The great majority of hydration sites are predicted to contribute favourably to the total free energy with respect to bulk water, though hydration sites close to non-polar regions of the solute do not contribute significantly. Analysis of a biomolecule with a positively and negatively charged functional group predicts that a charged species perturbs the free energy of water molecules to a distance of approximately 6.0 Å. Interestingly, short simulations are found to provide converged predictions if samples are taken with sufficient frequency, a finding that has the potential to significantly reduce the required computational cost of such analysis. In addition, the predicted thermodynamic properties of hydration sites with the potential for direct hydrogen bonding interactions are found to disagree significantly for two different water models. This study provides important information on how inhomogeneous fluid solvation theory can be employed to understand the structures and intermolecular interactions of biomolecules.

  15. [A study of brain inner tissue water molecule self-diffusion model based on Monte Carlo simulation].

    PubMed

    Wu, Zhanxiong; Zhu, Shanan; Bin, He

    2010-06-01

    The study of water molecule self-diffusion process is of importance not only for getting anatomical information of brain inner tissue, but also for shedding light on the diffusion process of some medicine in brain tissue. In this paper, we summarized the self-diffusion model of water molecule in brain inner tissue, and calculated the self-diffusion coefficient based on Monte Carlo simulation under different conditions. The comparison between this result and that of Latour model showed that the two self-diffusion coefficients were getting closer when the diffusion time became longer, and that the Latour model was a long time-depended self-diffusion model.

  16. Thermodynamic properties of water in the lattice gas model with consideration of the vibrational motions of molecules

    NASA Astrophysics Data System (ADS)

    Titov, S. V.; Tovbin, Yu. K.

    2016-11-01

    A molecular model developed earlier for a polar fluid within the lattice gas model is supplemented by considering the vibrational motions of molecules using water as an example. A combination of point dipole and Lennard-Jones potentials from SPC parametrization is chosen as the force field model for the molecule. The main thermodynamic properties of liquid water (density, internal energy, and entropy) are studied as functions of temperature. There is qualitative agreement between the calculation results and the experimental data. Ways of refining the molecular theory are discussed.

  17. Hydration of gelatin molecules in glycerol-water solvent and phase diagram of gelatin organogels.

    PubMed

    Sanwlani, Shilpa; Kumar, Pradip; Bohidar, H B

    2011-06-09

    We present a systematic investigation of hydration and gelation of the polypeptide gelatin in water-glycerol mixed solvent (glycerol solutions). Raman spectroscopy results indicated enhancement in water structure in glycerol solutions and the depletion of glycerol density close to hydration sheath of the protein molecule. Gelation concentration (c(g)) was observed to decrease from 1.92 to 1.15% (w/v) while the gelation temperature (T(g)) was observed to increase from 31.4 to 40.7 °C with increase in glycerol concentration. Data on hand established the formation of organogels having interconnected networks, and the universal gelation mechanism could be described through an anomalous percolation model. The viscosity of sol diverged as η ∼ (1 - c(g)/c)(-k) as c(g) was approached from below (c < c(g)), while the elastic storage modulus grew as G' ∼ (c/c(g) - 1)(t) (for c > c(g)). It is important to note that values determined for critical exponents k and t were universal; that is, they did not depend on the microscopic details. The measured values were k = 0.38 ± 0.10 and t = 0.92 ± 0.17 whereas the percolation model predicts k = 0.7-1.3 and t = 1.9. Isothermal frequency sweep studies showed power-law dependence of gel storage modulus (G') and loss modulus (G'') on oscillation frequency ω given as G'(ω) ∼ ω(n') and G''(ω) ∼ ω(n''), and consistent with percolation model prediction it was found that n' ≈ n'' ≈ δ ≈ 0.73 close to gelation concentration. We propose a unique 3D phase diagram for the gelatin organogels. Circular dichroism data revealed that the gelatin molecules retained their biological activity in these solvents. Thus, it is shown that the thermomechanical properties of these organogels could be systematically tuned and customized as per application requirement.

  18. Photodissociation of HBr molecules in clusters: from rare gas clusters to water nanoparticles

    NASA Astrophysics Data System (ADS)

    Fárník, M.; Buck, Udo

    2007-09-01

    Experiments on the photodissociation of molecules in different cluster environments are described and illustrated based on the example of HBr molecules photolysed at 193 nm in various clusters. The photolysis of HBr molecules incorporated in the hydrogen bonded network of (HBr)n clusters exhibits pronounced direct exits of the H-fragments. On the other hand, the H-fragments from HBr molecules bound by much weaker van der Waals forces at the surface of large Arn clusters are trapped efficiently by the cluster cage. These observations are mainly explained by the geometry of the molecule bound to the cluster. The HBr molecules deposited on the large (H2O)n clusters behave quite differently. They undergo acid dissociation and the resulting zwitterionic form is excited by the radiation giving rise to the generation of the hydronium H3O molecule and its subsequent dissociation.

  19. State of water molecules and silanol groups in opal minerals: a near infrared spectroscopic study of opals from Slovakia

    NASA Astrophysics Data System (ADS)

    Boboň, Miroslav; Christy, Alfred A.; Kluvanec, Daniel; Illášová, L'udmila

    2011-12-01

    Recently, near infrared spectroscopy in combination with double derivative technique has been effectively used by Christy (Vib Spectrosc 54:42-49, 2010) to study and differentiate between free and hydrogen bonded silanol groups on silica gel surface. The method has given some insight into the type of functionalities, their location in silica gel samples, and the way the water molecules bind onto the silanol groups. The important information in this respect comes from the overtones of the OH groups of water molecules hydrogen-bonded to free silanol groups, and hydrogen-bonded silanol groups absorbing in the region 5,500-5,100 cm-1. Chemically, opal minerals are hydrated silica and the same approach was adapted to study the state of water molecules, silanol functionalities, and their locations in opal samples from Slovakia. Twenty opal samples classified into CT and A classes and one quartz sample were used in this work. The samples were crushed using a hydraulic press and powderized. Each sample was then subjected to evacuation process to remove surface-adsorbed water at 200°C, and the near infrared spectrum of each sample was measured using a Perkin Elmer NTS FT-NIR spectrometer equipped with a transflectance accessory and a DTGS detector. The samples were also heated to 750°C to remove the hydrogen-bonded silanol groups on the surface to reveal their locality. Second derivative profiles of the near infrared reflectance spectra were obtained using the instrument's software and used in the detailed analysis of the samples. The analysis of the near infrared spectra and their second derivative profiles had the aim in finding relationships between the surface chemical structure and the classification of opal samples. The dry opal samples were also tested for their surface adsorption effectivity toward water molecules. The results indicate that the opal samples contain (1) surface-adsorbed water, (2) free and hydrogen-bonded silanol groups on the surface, (3) trapped

  20. Association of Catechin Molecules in Water: Quantitative Binding Study and Complex Structure Analysis.

    PubMed

    Ujihara, Tomomi; Hayashi, Nobuyuki

    2016-01-22

    Associations between catechin molecules were investigated by (1)H NMR titration experiments. Eight green tea catechins formed self-assembled dimers in water, and gallate-type catechins had a greater tendency to self-associate than non-gallate-type catechins. All eight catechins also associated as 1:1 heterodimer complexes. Investigation of complex formation of epigallocatechin-3-O-gallate (EGCg) and epigallocatechin (EGC) with the other catechins showed that the affinity between EGCg and 2,3-trans-gallate-type catechins was remarkably high, and the binding affinity of EGCg for ECg was also rather strong. In contrast, the non-gallate-type catechin EGC exhibited generally low binding affinity for other catechins. Structural analyses of the complexes by ROESY experiments and density functional theory calculations demonstrated that the higher binding abilities of gallate-type catechins are due to providing multiple intermolecular interactions that remain effective in an aqueous environment, such as aromatic/aromatic or CH/π interactions.

  1. The effect on structural and solvent water molecules of substrate binding to ferric horseradish peroxidase.

    PubMed

    Simpson, Niall; Adamczyk, Katrin; Hithell, Gordon; Shaw, Daniel J; Greetham, Gregory M; Towrie, Michael; Parker, Anthony W; Hunt, Neil T

    2015-01-01

    Ultrafast, multi-dimensional infrared spectroscopy, in the form of 2D-IR and pump-probe measurements, has been employed to investigate the effect of substrate binding on the structural dynamics of the horseradish peroxidase (HRP) enzyme. Using nitric oxide bound to the ferric haem of HRP as a sensitive probe of local dynamics, we report measurements of the frequency fluctuations (spectral diffusion) and vibrational lifetime of the NO stretching mode with benzohydroxamic acid (BHA) located in the substrate-binding position at the periphery of the haem pocket, in both D2O and H2O solvents. The results reveal that, with BHA bound to the enzyme, the local structural dynamics are insensitive to H/D exchange. These results are in stark contrast to those found in studies of the substrate-free enzyme, which demonstrated that the local chemical and dynamic environment of the haem ligand is influenced by water molecules. In light of the large changes in solvent accessibility caused by substrate binding, we discuss the potential for varying roles for the solvent in the haem pocket of HRP at different stages along the reaction coordinate of the enzymatic mechanism.

  2. Computing the energy of a water molecule using multideterminants: A simple, efficient algorithm

    SciTech Connect

    Clark, Bryan K.; Morales, Miguel A; Mcminis, Jeremy; Kim, Jeongnim; Scuseria, Gustavo E

    2011-01-01

    Quantum Monte Carlo (QMC) methods such as variational Monte Carlo and fixed node diffusion Monte Carlo depend heavily on the quality of the trial wave function. Although Slater-Jastrow wave functions are the most commonly used variational ansatz in electronic structure, more sophisticated wave functions are critical to ascertaining new physics. One such wave function is the multi-Slater- Jastrow wave function which consists of a Jastrow function multiplied by the sum of Slater deter- minants. In this paper we describe a method for working with these wave functions in QMC codes that is easy to implement, efficient both in computational speed as well as memory, and easily par- allelized. The computational cost scales quadratically with particle number making this scaling no worse than the single determinant case and linear with the total number of excitations. Addition- ally, we implement this method and use it to compute the ground state energy of a water molecule. 2011 American Institute of Physics. [doi:10.1063/1.3665391

  3. Two-dimensional description of surface-bounded exospheres with application to the migration of water molecules on the Moon

    NASA Astrophysics Data System (ADS)

    Schorghofer, Norbert

    2015-05-01

    On the Moon, water molecules and other volatiles are thought to migrate along ballistic trajectories. Here, this migration process is described in terms of a two-dimensional partial differential equation for the surface concentration, based on the probability distribution of thermal ballistic hops. A random-walk model, a corresponding diffusion coefficient, and a continuum description are provided. In other words, a surface-bounded exosphere is described purely in terms of quantities on the surface, which can provide computational and conceptual advantages. The derived continuum equation can be used to calculate the steady-state distribution of the surface concentration of volatile water molecules. An analytic steady-state solution is obtained for an equatorial ring; it reveals the width and mass of the pileup of molecules at the morning terminator.

  4. Isomerization of HNO to HON in the singlet state assisted by amino acid residues and/or water molecules

    NASA Astrophysics Data System (ADS)

    Shi, Junyou; Li, Ping; Bu, Yuxiang; Wang, Weihua; Mou, Zhaoxia; Song, Rui

    The effects of amino acid residues in the presence or absence of water molecules on the isomerization of the singlet state of HNO/HON have been systematically investigated at the B3LYP/6-311++G** level of theory. The structural characteristics, proton transfer (PT) mechanisms, and the corresponding thermodynamic and kinetic parameters, have been discussed, respectively. All the optimized complexes have been characterized by the ring structures through the intermolecular H-bonds. The origin of the increase in N bond H stretching frequency (blue shifts) occurring in the reactants has also been investigated using the natural bonding orbital (NBO) analyses, which is mainly attributed to the decrease of the electron densities in the antibonding orbital of the N bond H bonds as well as the increase of the polarization of the N bond H bond. All the PTs proceed with the concerted mechanisms since no ionic intermediates have been located during PT processes. At the same time, the cooperative effects of amino acid residues and water molecules on the selected PT processes have been observed, where the PTs assisted solely by the selected residues cannot occur without the participation of the water molecule. Overall, the introductions of one or two water molecules are more favorable for the isomerization of HNO assisted by the amino acid residues.

  5. Modeling the impacts of winter cover crops on water quality in two adjacent sub-watersheds within the Chesapeake Bay Watershed, Maryland, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Choptank River on Maryland’s Eastern Shore has been designated by the USEPA as “impaired waters” under Section 303(d) of the Federal Clean Water Act of 1972, mainly because of significant nutrient loads that resulted in not meeting the EPA water quality standards. This water quality deteriorati...

  6. Molecular interactions of organic molecules at the air/water interface investigated by sum frequency generation vibrational spectroscopy.

    PubMed

    Wang, Wenting; Ye, Shuji

    2017-02-08

    The molecular structure and dynamics of organic molecules at the aqueous interface have attracted a number of investigations owing to their importance and specific nature. However, there are relatively few studies on the direct characterization of the molecular interactions at the air/water interface because they are extremely difficult to measure in experiments. In this study, we use dibutyl ester molecules (R1CO2R2O2CR1) as a model of organic molecules, and investigate their molecular structure and interactions using sum frequency generation vibrational spectroscopy. We demonstrate that the molecular interactions can be estimated by measuring the intensity ratio of the symmetric stretching (ν1) and Fermi resonant bands (2ν2) of methyl groups. Here, dibutyl ester molecules are widely used as plasticizers in polymers to improve the properties of the plastics and polymers. It is found that the orientation angles of the tailed methyl groups at the air/water interface decrease from 34° to 19° when the chain length of R2 increases from 0 to 8. The total intermolecular interactions of the dibutyl ester molecules decrease as the chain length of R2 increases because the van der Waals interactions between the hydrocarbon chains increase, while the hydrogen bond interactions between the carbonyl group and water molecules decrease. Our study demonstrates the stability of ester-based plasticizers in polymers can be well predicted from the intensity ratio of the ν1 and 2ν2 bands of methyl group. Such an intensity ratio can be thus used as an effective vibrational optical ruler for characterizing molecular interactions between plasticizers and polymers.

  7. Extraction of Organic Molecules from Terrestrial Material: Quantitative Yields from Heat and Water Extractions

    NASA Technical Reports Server (NTRS)

    Beegle, L. W.; Abbey, W. A.; Tsapin, A. T.; Dragoi, D.; Kanik, I.

    2004-01-01

    In the robotic search for life on Mars, different proposed missions will analyze the chemical and biological signatures of life using different platforms. The analysis of samples via analytical instrumentation on the surface of Mars has thus far only been attempted by the two Viking missions. Robotic arms scooped relogith material into a pyrolysis oven attached to a GC/MS. No trace of organic material was found on any of the two different samples at either of the two different landing sites. This null result puts an upper limit on the amount of organics that might be present in Martian soil/rocks, although the level of detection for each individual molecular species is still debated. Determining the absolute limit of detection for each analytical instrument is essential so that null results can be understood. This includes investigating the trade off of using pyrolysis versus liquid solvent extraction to release organic materials (in terms of extraction efficiencies and the complexity of the sample extraction process.) Extraction of organics from field samples can be accomplished by a variety of methods such utilizing various solvents including HCl, pure water, supercritical fluid and Soxhelt extraction. Utilizing 6N HCl is one of the most commonly used method and frequently utilized for extraction of organics from meteorites but it is probably infeasible for robotic exploration due to difficulty of storage and transport. Extraction utilizing H2O is promising, but it could be less efficient than 6N HCl. Both supercritical fluid and Soxhelt extraction methods require bulky hardware and require complex steps, inappropriate for inclusion on rover spacecraft. This investigation reports the efficiencies of pyrolysis and solvent extraction methods for amino acids for different terrestrial samples. The samples studied here, initially created in aqueous environments, are sedimentary in nature. These particular samples were chosen because they possibly represent one of the

  8. The Formation of Oxygen-Containing Molecules in Liquid Water Environments on the Surface of Titan (Invited)

    NASA Astrophysics Data System (ADS)

    Neish, C.

    2010-12-01

    Saturn’s moon Titan represents a unique locale for studying prebiotic chemistry. Reactions occurring in its thick nitrogen - methane atmosphere produce a wide variety of organic molecules. Observations by the Voyager spacecraft found evidence for six gas-phase hydrocarbons and three nitriles, along with an enveloping haze layer shrouding the surface of the moon (Hanel et al., 1981; Kunde et al., 1981; Maguire et al., 1981). More recently, the INMS instrument on the Cassini spacecraft has found evidence for organic molecules up to its mass limit of 100 Da at altitudes as high as 1200 km (Waite et al., 2005; Vuitton et al. 2007). Laboratory experiments that simulate the reactions occurring in Titan’s atmosphere produce many of the same organic molecules observed by Voyager and Cassini, along with organic precipitates known as tholins. Tholins have the general formula CxHyNz and are spectrally similar to Titan’s haze (Khare et al., 1984). Though interesting from the point of view of organic chemistry, the molecules found in Titan’s atmosphere stop short of addressing questions related to the origins of life. Oxygen - a key element for most known biological molecules - is generally lacking in Titan’s atmosphere. The most abundant oxygenated molecule, CO, is present at only ~50 ppm (de Kok et al., 2007). However, if Titan’s atmospheric organic molecules mix with water found in cryovolcanic lavas or impact melts, they may react to produce oxygen-containing, prebiotic species. In this paper, I will show that reactions between Titan tholins and low temperature aqueous solutions produce a wide variety of oxygen-containing species. These reactions display first-order kinetic behaviour with half-lives between 0.4 to 7 days at 273 K (in water) and between 0.3 and 14 days at 253 K (in 13 wt. % ammonia-water). Tholin hydrolysis is thus very fast compared to the freezing timescales of impact melts and volcanic sites on Titan, which take hundreds to thousands of years

  9. Simulated effects of impoundment of lake seminole on ground-water flow in the upper Floridan Aquifer in southwestern Georgia and adjacent parts of Alabama and Florida

    USGS Publications Warehouse

    Jones, L. Elliott; Torak, Lynn J.

    2004-01-01

    Hydrologic implications of the impoundment of Lake Seminole in southwest Georgia and its effect on components of the surface- and ground-water flow systems of the lower Apalachicola?Chattahoochee?Flint (ACF) River Basin were investigated using a ground-water model. Comparison of simulation results of postimpoundment drought conditions (October 1986) with results of hypothetical preimpoundment conditions (a similar drought prior to 1955) provides a qualitative measure of the changes in hydraulic head and ground-water flow to and from streams and Lake Seminole, and across State lines caused by the impoundment. Based on the simulation results, the impoundment of Lake Seminole changed ground-water flow directions within about 20?30 miles of the lake, reducing the amount of ground water flowing from Florida to Georgia southeast of the lake. Ground-water storage was increased by the impoundment, as indicated by a simulated increase of as much as 26 feet in the water level in the Upper Floridan aquifer. The impoundment of Lake Seminole caused changes to simulated components of the ground-water budget, including reduced discharge from the Upper Floridan aquifer to streams (315 million gallons per day); reduced recharge from or increased discharge to regional ground-water flow at external model boundaries (totaling 183 million gallons per day); and reduced recharge from or increased discharge to the undifferentiated overburden (totaling 129 million gallons per day).

  10. Limnological characteristics of selected lakes in the Nebraska sandhills, U.S.A., and their relation to chemical characteristics of adjacent ground water

    USGS Publications Warehouse

    La Baugh, J.W.

    1986-01-01

    Limnological characteristics of Crane, Hackberry, Island and Roundup Lakes, and chemical characteristics of shallow ground water, within the Crescent Lake National Wildlife Refuge, western Nebraska, were determined during a preliminary investigation of the interaction between lakes and ground water in this study area between 1980 and 1984. When ice cover was absent, the lakes were well-mixed vertically, regardless of season. Depth to which 1% of surface illumination penetrated was commonly less than 1m. Variability in light penetration, as measured by Secchidisk transparency, appeared to be unrelated to changes in algal biomass, even though algal biomass, measured as chlorophyll a, varied seasonally within a two-order-of-magnitude range. Blue-green algae were the most abundant phytoplankton; this condition occurred most often when the ratio of total nitrogen to total phosphorus in the lakes' water was less than 29. Although rotifers and copepod naupli commonly were the most abundant zooplankton in the lakes, cladocerans were dominant occasionally. Either sodium or calcium was the most abundant cation, and bicarbonate was the most abundant anion, in water from water-table wells and lakes sampled during the study. The second most abundant cation in the ground water was related to the location of the sampled well within the ground-water system. The lakes were a source of dissolved organic carbon seeping to ground water. Chemical and hydrologic data indicate there is interaction between lakes and ground water in the study area. ?? 1986.

  11. Subpicosecond energy transfer from a highly intense THz pulse to water: A computational study based on the TIP4P/2005 rigid-water-molecule model.

    PubMed

    Mishra, Pankaj Kr; Vendrell, Oriol; Santra, Robin

    2016-03-01

    The dynamics of ultrafast energy transfer to water clusters and to bulk water by a highly intense, subcycle THz pulse of duration ≈150 fs is investigated in the context of force-field molecular dynamics simulations. We focus our attention on the mechanisms by which rotational and translational degrees of freedom of the water monomers gain energy from these subcycle pulses with an electric field amplitude of up to about 0.6 V/Å. It has been recently shown that pulses with these characteristics can be generated in the laboratory [C. Vicario, B. Monoszlai, and C. P. Hauri, Phys. Rev. Lett. 112, 213901 (2014)]. Through their permanent dipole moment, water molecules are acted upon by the electric field and forced off their preferred hydrogen-bond network conformation. This immediately sets them in motion with respect to one another as energy quickly transfers to their relative center of mass displacements. We find that, in the bulk, the operation of these mechanisms is strongly dependent on the initial temperature and density of the system. In low density systems, the equilibration between rotational and translational modes is slow due to the lack of collisions between monomers. As the initial density of the system approaches 1 g/cm(3), equilibration between rotational and translational modes after the pulse becomes more efficient. In turn, low temperatures hinder the direct energy transfer from the pulse to rotational motion owing to the resulting stiffness of the hydrogen bond network. For small clusters of just a few water molecules we find that fragmentation due to the interaction with the pulse is faster than equilibration between rotations and translations, meaning that the latter remain colder than the former after the pulse. In contrast, clusters with more than a few tens of water molecules already display energy gain dynamics similar to water in condensed phases owing to inertial confinement of the internal water molecules by the outer shells. In these cases

  12. Reaction Kinetics of Water Molecules with Oxygen Vacancies on Rutile TiO2(110)

    SciTech Connect

    Petrik, Nikolay G.; Kimmel, Gregory A.

    2015-09-16

    The formation of bridging hydroxyls (OHb) via reactions of water molecules with oxygen vacancies (VO) on reduced TiO2(110) surfaces is studied using infrared reflection-absorption spectroscopy (IRAS), electron-stimulated desorption (ESD), and photon-stimulated desorption (PSD). Narrow IRAS peaks at 2737 cm-1 and 3711 cm-1 are observed for stretching vibrations of ODb and OHb on TiO2(110), respectively. IRAS measurements with s- and p-polarized light demonstrate that the bridging hydroxyls are oriented normal to the (110) surface. The IR peaks disappear after the sample is exposed to O2 or annealed in the temperature range of 400 – 600 K (correlating with the temperature at which pairs of OHb’s reform water and then desorb), which is consistent with their identification as bridging hydroxyls. We have studied the kinetics of water reacting with the vacancies by monitoring the formation of bridging hydroxyls (using IRAS) as a function of the annealing temperature for a small amount of water initially dosed on the TiO2(110) at low temperature. Separate experiments have also monitored the loss of water molecules (using water ESD) and vacancies (using the CO photooxidation reaction) due to the reactions of water molecules with the vacancies. All three techniques show that the reaction rate becomes appreciable for T > 150 K and that the reactions largely complete for T > 250 K. The temperature-dependent water-VO reaction kinetics are consistent with a Gaussian distribution of activation energies with Ea = 0.545 eV, ΔEa(FWHM) = 0.125 eV, and a “normal” prefactor, v = 1012 s-1. In contrast, a single activation energy with a physically reasonable prefactor does not fit the data well. Our experimental activation energy is close to theoretical estimates for the diffusion of water molecules along the Ti5c rows on the reduced TiO2

  13. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2012

    USGS Publications Warehouse

    Beman, Joseph E.

    2013-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25-40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. A population increase of about 20 percent in the basin from 1990 to 2000 and a 22 percent increase from 2000 to 2010 resulted in an increased demand for water. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2012), the network consists of 126 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (ABCWUA), currently (2012) measures and reports water levels from the 126 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 126 sites through water year 2012.

  14. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2010

    USGS Publications Warehouse

    Beman, Joseph E.

    2011-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25-40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. An increase of about 20 percent in the basin human population from 1990 to 2000 and about a 22 percent increase from 2000 to 2010 also resulted in an increased demand for water. A network of wells was established by the U.S. Geological Survey in cooperation with the City of Albuquerque to monitor changes in groundwater levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2010), the network consists of 124 wells and piezometers (a piezometer is a small-diameter subwell usually nested within a larger well). To better help the Albuquerque Bernalillo County Water Utility Authority manage water use, this report presents water-level data collected by U.S. Geological Survey personnel at those 124 sites through water year 2010.

  15. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2011

    USGS Publications Warehouse

    Beman, Joseph E.

    2012-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. An increase of about 20 percent in the basin human population from 1990 to 2000 and of about 22 percent increase from 2000 to 2010 also resulted in an increased demand for water. A network of wells was established by the U.S. Geological Survey in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2011), the network consists of 126 wells and piezometers (a piezometer is a specialized well open to a specific depth in the aquifer and is often of small diameter and nested with other piezometers open to different depths). This report presents water-level data collected by U.S. Geological Survey personnel at those 126 sites through water year 2011 to better help the Albuquerque Bernalillo County Water Utility Authority manage water use.

  16. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2013

    USGS Publications Warehouse

    Beman, Joseph E.

    2014-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when treatment and distribution of surface water from the Rio Grande began. A population increase of about 20 percent in the basin from 1990 to 2000 and a 22-percent increase from 2000 to 2010 resulted in an increased demand for water. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2013), the network consists of 123 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the Albuquerque Bernalillo County Water Utility Authority, currently (2013) measures and reports water levels from the 123 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 123 sites through water year 2013.

  17. Hydrology and water quality of a field and riparian buffer adjacent to a mangrove wetland in Jobos Bay Watershed, Puerto Rico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Models that estimate the effects of agricultural conservation practices on water quantity and quality have become increasingly important tools for short- and long-term assessments. In this study, we simulated the water quality and hydrology of a portion of the Jobos Bay watershed, Puerto Rico using...

  18. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2014

    USGS Publications Warehouse

    Beman, Joseph E.

    2015-10-21

    An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the basin. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. The network currently (2014) consists of 125 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the Albuquerque Bernalillo County Water Utility Authority, currently (2014) measures and reports water levels from the 125 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 125 sites through water year 2014 (October 1, 2013, to September 30, 2014).

  19. [Calculation of the amount of free water molecules in aqueous solutions by means of spectral parameters from the terahertz frequency domain taking into account processes of screening].

    PubMed

    Pen'kov, N V; Iashin, V A; Fesenko, E E; Fesenko, E E

    2014-01-01

    In this paper we derive a formula to calculate the amount of free water molecules in solution. Physical values in this formula may be obtained by analyzing the spectra of aqueous solutions in the terahertz frequency range. Formula is derived on the basis of considering water polarization process in electric field. It is shown that without processes of shielding the electric field in the water calculations lead to very high estimation of a share of free water molecule.

  20. Water-Level Data for the Albuquerque Basin and Adjacent Areas, Central New Mexico, Period of Record Through September 30, 2008

    USGS Publications Warehouse

    Beman, Joseph E.

    2009-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin are currently (2008) obtained soley from ground-water resources. An increase of about 20 percent in the population from 1990 to 2000 also resulted in an increased demand for water. A network of wells was established to monitor changes in ground-water levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2008), the network consists of 144 wells and piezometers. This report presents water-level data collected by U.S. Geological Survey personnel at 125 sites through water-year 2008. In addition, data from 19 wells (Sites 127-30, 132-134, 136, 138-142 and 144-149) owned, maintained, and measured by Sandia National Laboratories are presented in this report.

  1. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2015

    USGS Publications Warehouse

    Beman, Joseph E.; Bryant, Christina F.

    2016-10-27

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 may have resulted in an increased demand for water in areas within the basin.An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. The network currently (2015) consists of 124 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the ABCWUA, currently (2015) measures and reports water levels from the 124 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 124 sites through water year 2015 (October 1, 2014, through September 30, 2015).

  2. Discharge, suspended sediment, and salinity in the Gulf Intracoastal Waterway and adjacent surface waters in South-Central Louisiana, 1997–2008

    USGS Publications Warehouse

    Swarzenski, Christopher M.; Perrien, Scott M.

    2015-10-19

    River water penetrates much of the Louisiana coast, as demonstrated by the large year-to-year fluctuations in salinity regimes of intradistributary basins in response to differences in flow regimes of the Mississippi and the Atchafalaya Rivers. This occurs directly through inflow along the GIWW and through controlled diversions and indirectly by transport into basin interiors after mixing with the Gulf of Mexico. The GIWW plays an important role in moderating salinity in intradistributary basins; for example, salinity in surface waters just south of the GIWW between Bayou Boeuf and the Houma Navigation Canal remained low even during a year with prolonged low water (2000).

  3. Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2009

    USGS Publications Warehouse

    Beman, Joseph E.; Torres, Leeanna T.

    2010-01-01

    The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25 to 40 miles wide. The basin is defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompass the structural Rio Grande Rift within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when surface water from the Rio Grande began being treated and integrated into the system. An increase of about 20 percent in the population from 1990 to 2000 also resulted in an increased demand for water. A network of wells was established to monitor changes in groundwater levels throughout the basin from April 1982 through September 1983. This network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly in 1983. Currently (2009), the network consists of 131 wells and piezometers. This report presents water-level data collected by U.S. Geological Survey personnel at 123 sites through water year 2009. In addition, data from four wells (Sites 140, 147, 148, and 149) owned, maintained, and measured by Sandia National Laboratories and three from Kirtland Air Force Base (Sites 119, 125, and 126) are presented in this report.

  4. Degradation of bacterial quorum sensing signaling molecules by the microscopic yeast Trichosporon loubieri isolated from tropical wetland waters.

    PubMed

    Wong, Cheng-Siang; Koh, Chong-Lek; Sam, Choon-Kook; Chen, Jian Woon; Chong, Yee Meng; Yin, Wai-Fong; Chan, Kok-Gan

    2013-09-25

    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.

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

    PubMed Central

    Wong, Cheng-Siang; Koh, Chong-Lek; Sam, Choon-Kook; Chen, Jian Woon; Chong, Yee Meng; Yin, Wai-Fong; Chan, Kok-Gan

    2013-01-01

    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. PMID:24072030

  6. Estimation of adsorption energy for water molecules on a multi-walled carbon nanotube thin film by measuring electric resistance

    NASA Astrophysics Data System (ADS)

    Kokabu, Takuya; Inoue, Shuhei; Matsumura, Yukihiko

    2016-11-01

    Gas sensors based on carbon nanotube (CNT) films have attracted attention owing to their low power consumption. For further development of these sensors, we need to understand the surface interaction of the films with gas molecules. In our previous research, we investigated the influence of water molecules on the electrical conductance of multi-walled CNT films and explained this phenomenon using a two-layer adsorption model. This work motivated us to measure the adsorption energy of CNT-H2O. In this study, we focused on the first-layer adsorption and investigated the sheet resistance to water vapor pressure at various temperatures using the transmission line method (TLM). The results were fitted to Langmuir adsorption model and the adsorption equilibrium constant was determined. The temperature dependence of the sheet resistance followed a model of fluctuation induced tunneling (FIT), in which the energy barrier at the CNT junction is regarded as the main factor influencing the electrical conductance of the CNT film. The sheet resistance and equilibrium constant decreased as temperature increased. This result was consistent with the adsorption phenomenon. Finally, the adsorption energy was determined to be 0.22-0.31 eV, which is larger than the previously calculated value. It was also reported that the adsorption energy of the gas molecules in the interstitial site between two carbon nanotubes was larger than that on the CNT surface. These results indicate that the CNT junction plays a key role in the detection of gas molecules.

  7. Water and Streambed Sediment Quality, and Ecotoxicology of a Stream along the Blue Ridge Parkway, Adjacent to a Closed Landfill, near Roanoke, Virginia: 1999

    USGS Publications Warehouse

    Ebner, Donna Belval; Cherry, Donald S.; Currie, Rebecca J.

    2004-01-01

    A study was done of the effects of a closed landfill on the quality of water and streambed sediment and the benthic macroinvertebrate community of an unnamed stream and its tributary that flow through Blue Ridge Parkway lands in west-central Virginia. The primary water source for the tributary is a 4-inch polyvinyl chloride (PVC) pipe that protrudes from the slope at the base of the embankment bordering the landfill. An unusual expanse of precipitate was observed in the stream near the PVC pipe. Stream discharge was measured and water and streambed sediment samples were collected at a nearby reference site and at three sites downstream of the landfill in April and September 1999. Water samples were analyzed for major ions, nitrate, total and dissolved metals, total dissolved solids, total organic carbon, and volatile and semivolatile organic compounds, including organochlorine pesticides and polychlorinated biphenyls (PCBs). Streambed sediment samples were analyzed for total metals, total organic carbon, percent moisture, and volatile and semivolatile organic compounds, including organochlorine pesticides and PCBs. The benthic macroinvertebrate community within the stream channel also was sampled at the four chemical sampling sites and at one additional site in April and September. Each of the five sites was assessed for physical habitat quality. Water collected periodically at the PVC pipe discharge between November 1998 and November 1999 was used to conduct 48-hour acute and 7-day chronic toxicity tests using selected laboratory test organisms. Two 10-day chronic toxicity tests of streambed sediments collected near the discharge pipe also were conducted. Analyses showed that organic and inorganic constituents in water from beneath the landfill were discharged into the sampled tributary. In April, 79 percent of inorganic constituents detected in water had their highest concentrations at the site closest to the landfill; at the same site, 59 percent of inorganic

  8. Self-assembly of neuroprotective carbazolium based small molecules at octane/water interface: A simulation investigation

    NASA Astrophysics Data System (ADS)

    Zolghadr, Amin Reza; Heydari Dokoohaki, Maryam

    2016-11-01

    The self-assembly of dibromocarbazole based small molecule (P7C3) and its analogues is studied at the octane/water interface by using molecular dynamics simulations. P7C3 protects newborn neurons from apoptotic cell death and enhances neurogenesis. The bromines on the carbazole appear particularly important, as the derivatives with dichloro and parent carbazole did not appear active at the concentrations tested. We are mainly focused on the question that why is dibromocarbazole derivative an effective neuroprotective drug, but not dichlorocarbazole or parent carbazole? It was found that P7C3 and P7C3-Cl were concentrated in the interfacial region, whereas the parent carbazole derivative were distributed throughout the water phase. The diffusion of P7C3 molecules in the interfacial region are higher than P7C3-Cl. This approach could use by experimentalist to evaluate the permeability of drug candidates prior to their synthesis.

  9. Engineering and Environmental Study of DDT Contamination of Huntsville Spring Branch, Indian Creek, and Adjacent Lands and Waters, Wheeler Reservoir, Alabama. Volume 2. Appendices I-III.

    DTIC Science & Technology

    1980-11-01

    5.2 AQUATIC INVERTEBRATES 1-45 5.3 AQUATIC VERTEBRATES 1-46 5.4 BIRDS 1-56 5.5 MAMMALS 1-59 5.6 ALGAE AND FUNGI 1-59 6.0 EPA AMBIENT WATER QUALITY...AQUATIC INVERTEBRATES 1-45 5.3 AQUATIC VERTEBRATES 1-46 5.4 BIRDS 1-56 5.5 MAMMALS 1-59 5.6 ALGAE AND FUNGI 1-59 *’ 6.0 EPA AMBIENT WATER QUALITY...non-human toxicology of DOT; 4) EPA’s ambient water quality criteria; and 5) FDA’s regulations regarding DDT in fish. 2.0 PHYSICAL AND CHEMICAL

  10. Matrix IR spectra and quantum-chemical calculations of the products of small nickel cluster interactions with water molecules

    NASA Astrophysics Data System (ADS)

    Serebrennikov, L. V.; Dalvyatshin, D. I.; Golovkin, A. V.

    2010-12-01

    Reactions of Ni n clusters with water molecules were studied by IR spectroscopy in inert matrices and quantum chemistry methods. The geometric configurations, total energies, and vibrational frequencies of all the possible Ni2(H2O) and Ni3(H2O) isomers were calculated. For both systems, the main minima and transition states were found. Water was shown to dissociate to hydrogen and hydroxyl in the reactions, and, in all the complexes formed, hydrogen is situated in the bridge position on the Ni-Ni bond.

  11. Evaluation of low-temperature geothermal potential in Utah and Goshen Valleys and adjacent areas, Utah. Part II. Water temperature and chemistry

    SciTech Connect

    Klauk, R.H.; Davis, D.A.

    1984-12-01

    Geothermal reconnaissance techniques have identified five areas in Utah County warranting further investigation for low-temperature geothermal resources. One area in northern Utah Valley is along Utah Lake fault zone and includes Saratoga Hot Springs. Water temperatures within this area range from 21 to 43/sup 0/C. Common ion analyses as well as B and Li concentrations indicate waters sampled in this area are anomalous when compared to other samples from the same aquifer. Two other areas in southern Utah Valley also coincide with the Utah Lake fault zone. Common ion analyses, trace element concentrations, and C1/HCO/sub 3/ ratios distinguish these areas from all other waters in this valley. Temperatures within these southern areas range from 21 to 32/sup 0/C. All three thermal areas are possibly the result of deep circulation of meteoric water being warmed and subsequently migrating upward within the Utah Lake fault zone. The Castilla Hot Springs area has been expanded by this study to include a spring located 3 mi further up Spanish Fork Canyon near the Thistle earthflow. A temperature of 50/sup 0/C was recorded for this spring and chemistry is similar to Castilla. In Goshen Valley, the fifth geothermal area identified, measured temperatures range from 20 to 27/sup 0/C for some wells and springs. Chemical analyses, however, do not discern the location of low-temperature geothermal reservoirs. 18 refs., 7 figs., 5 tabs.

  12. A look deep inside the a hillslope reveals a structured heterogeneity of isotopic reservoirs and distinct water use strategies for adjacent trees

    NASA Astrophysics Data System (ADS)

    Oshun, J.; Rempe, D. M.; Link, P.; Simonin, K. A.; Dietrich, W.; Dawson, T. E.; Fung, I.

    2012-12-01

    Whereas recent studies have begun to note the importance of weathered rock as a source of moisture for vegetation and, through transpiration, as a moderator of local and regional climate, no study has looked deeply into a hillslope in three-dimensions to explore dynamics in the hydrologic cycle and tree water use. Here, we use natural abundance stable isotope techniques to reveal distinct isotopic reservoirs within the hillslope, as well as quantify the movement of water from weathered rock and soil into vegetation. Our study site, at the Angelo Coast Range Reserve in Northern California, is a 4000 m2 unchanneled catchment that drains into Elder Creek, in the South Fork of the Eel River basin. Although average annual rainfall is 1900mm, 90% falls between October and May, forcing vegetation to find deep sources of moisture to survive the dry summer. An old-growth mixed conifer forest with trees as tall as 65 m grows on a 38° slope, with soils 10-60 cm thick underlain by vertically dipping, weathered turbidite sequences of the Coastal Franciscan Belt. A perched seasonally drains to unweathered bedrock. The water table fluctuates between 3 and 5 m below the surface near Elder Creek, and between 18 and 24 m below the surface at the hillslope divide. The site contains over 850 sensors monitoring the climatic variables and the movement of water through the subsurface, vegetation and into the atmosphere. Daily rainwater sampling during storm events from 2007-2012 shows a Local Meteoric Water Line, setting the context for our comparison of isotopic reservoirs. From Summer 2011 to Fall 2012, bi-weekly to tri-weekly samples were collected of tree xylem of over 30 individuals of Pseudotsuga menziesii, quercus agrifolia, arbutus menziesii, Umbellularia californica, Notholithocarpus densiflorus, acer macrophyllum, as well as from soil and rock to a depth of 1-1.3 m, and from the water table at 12 wells across the hillslope. Analysis reveals a structured heterogeneity of

  13. Control of water molecule aggregations in copper 1,4-cyclohexanedicarboxylate coordination polymers containing pyridyl-piperazine type ligands

    NASA Astrophysics Data System (ADS)

    Qiblawi, Sultan H.; LaDuca, Robert L.

    2014-01-01

    A series of layered divalent copper coordination polymers containing 1,4-cyclohexanedicarboxylate and long-spanning pyridyl-piperazine type ligands exhibits greatly different co-crystallized water molecule aggregations depending on the specific ligands used. Both [Cu(t-14cdc)(4-bpmp)]n (1, t-14cdc = trans-1,4-cyclohexanedicarboxylate, 4-bpmp = bis(4-pyridylmethyl)piperazine) and {[Cu(t-14cdc)(4-bpfp)(H2O)2]·6H2O}n (2, 4-bpfp = bis(4-pyridylformyl)piperazine) possess 2D (4,4) coordination polymer grids. However 1 lacks any co-crystallized water and has pinched grid apertures, while 2 manifests infinite water tapes with T6(2)4(2) classification and rectangular grid apertures. {[Cu2(c-14cdc)2(4-bpmp)]·2H2O}n (3, c-14cdc = cis-1,4-cyclohexanedicarboxylate) has [Cu2(c-14cdc)]2 ribbons with paddlewheel dimeric units linked into 2D slabs by 4-bpmp tethers, along with isolated water molecule pairs. In contrast, {[Cu2(c-14cdc)2(4-bpfp)]·10H2O}n (4) shows a very similar underlying coordination polymer topology but entrains unique decameric water molecule clusters. The minor product {[Cu2(c-14cdcH)2(t-1,4-cdc)(4-bpfp)2(H2O)2]·2H2O}n (5) was isolated along with 4; this compound underwent some in situ cis to trans cyclohexane-dicarboxylate ligand isomerization and exhibits a ladder polymer motif.

  14. Effects of water molecules on the chemical stability of MAGeI3 perovskite explored from a theoretical viewpoint.

    PubMed

    Sun, Ping-Ping; Chi, Wei-Jie; Li, Ze-Sheng

    2016-09-21

    The stability of perovskite in humid environments is one of the biggest obstacles for its potential applications in light harvesting and electroluminescent displays. Understanding the detailed degradation mechanism of MAGeI3 in moisture is a critical way to explore the practicability of MAGeI3 perovskite. In this study, we report a quantitative and systematic investigation of MAGeI3 degradation processes by exploring the effects of H2O molecules on the structural and electronic properties of the most stable MAGeI3(101) surface under various simulated environmental conditions with different water coverage based on first-principles calculations. The results show that H2O molecules can easily diffuse into the inner side of the perovskite and gradually corrode the structure as the number of H2O molecules increases. As a result of the interactions between perovskite and H2O molecules, a hydrated intermediate will be generated as the first step in the degradation mechanism; the perovskite will further decompose to HI and GeI2. In terms of one MAGeI3 molecule, it will be dissociated completely to GeI2 as a result of hydrolysis reactions with a minimum of 4H2O molecules. In addition, the degradation of the perovskite will also affect the electronic structure, causing a decrease in optical absorption across the visible region of the spectrum and a distinct deformation change in the crystal structure of the material. These findings further illustrate the degradation of the hydrolysis process of MAGeI3 perovskite in humid environments, which should be helpful to inspire experimentalists to take action to prolong the lifetimes of perovskite solar cells to achieve high conversion efficiency in their applications.

  15. Excitation of water molecules by electron impact with formation of OH-radicals in the A2Σ+ state

    NASA Astrophysics Data System (ADS)

    Khodorkovskii, M. A.; Murashov, S. V.; Artamonova, T. O.; Rakcheeva, L. P.; Beliaeva, A. A.; Shakhmin, A. L.; Michael, D.; Timofeev, N. A.; Mel'nikov, A. S.; Shevkunov, I. A.; Zissis, G.

    2009-11-01

    The excitation cross-sections of the OH-radical band A2Σ+ → X2 (v' = 0 → v'' = 0, v' = 1 → v'' = 1) were measured. OH-radicals were formed during dissociation of water molecules by electron impact in the conditions of crossing of supersonic molecular and electron beams in the energy range 10-120 eV. Measurements were conducted at temperatures of 50, 80 and 200 K. It was shown that the excitation function had a sharp maximum in the region of low energies (at 16 eV) and an extended plateau up to 120 eV. It is proved that there are two channels of molecule dissociation with formation OH (A2Σ+) through excitation of either the triplet b3A1 or the singlet B1A1 states of H2O molecules. The form of the excitation function essentially depends on the temperature of water vapours in the beam. With the decrease of the water molecule temperature the height of the plateau in the region 30-120 eV decreases in comparison with that of the peak at 16 eV. The absolute value of the excitation cross-section of the OH band at the temperature 50 K has been measured. It is equal to (1.6 ± 0.5) × 10-18 cm2 in the maximum at 16 eV. The ratio of cross-sections of bands 1-1 and 0-0 weakly depends on the energy of the exciting electron in the range 12-120 eV and is equal to 0.28 ± 0.05. The appearance threshold is equal to (9.1 ± 0.5) eV.

  16. In situ spectroradiometric calibration of EREP imagery and estuarine and coastal oceanography of Block Island sound and adjacent New York coastal waters. [Willcox, Arizona

    NASA Technical Reports Server (NTRS)

    Yost, E. F. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. The first part of the study resulted in photographic procedures for making multispectral positive images which greatly enhance the color differences in land detail using an additive color viewer. An additive color analysis of the geologic features near Willcox, Arizona using enhanced black and white multispectral positives allowed compilation of a significant number of unmapped geologic units which do not appear on geologic maps of the area. The second part demonstrated the feasibility of utilizing Skylab remote sensor data to monitor and manage the coastal environment by relating physical, chemical, and biological ship sampled data to S190A, S190B, and S192 image characteristics. Photographic reprocessing techniques were developed which greatly enhanced subtle low brightness water detail. Using these photographic contrast-stretch techniques, two water masses having an extinction coefficient difference of only 0.07 measured simultaneously with the acquisition of S190A data were readily differentiated.

  17. Aquatic risk assessment of pesticides in surface waters in and adjacent to the Everglades and Biscayne National Parks: I. Hazard assessment and problem formulation.

    PubMed

    Carriger, John F; Rand, Gary M

    2008-10-01

    An aquatic risk assessment under the U.S. Environment Protection Agency (EPA) ecological risk framework was conducted for atrazine, metolachlor, malathion, chlorpyrifos, and endosulfan in the C-111 freshwater basin (eastern boundary of the Everglades National Park), northeast Florida Bay, and south Biscayne Bay in South Florida. Based on the use of the hazard quotient approach, measured concentrations of chlorpyrifos and endosulfan in surface waters suggest potential hazards to aquatic organisms and were, therefore, considered as chemicals of potential ecological concern (COPECs). The problem formulation included an overview of the physical/chemical and environmental fate characteristics and aquatic toxicology of the COPECs. Background surface water exposure concentrations of endosulfan and toxicity data from laboratory and field studies indicate that fish and invertebrate mortality may be a concern when endosulfan is applied in agricultural areas near aquatic ecosystems.

  18. Role of Interfacial Water Molecules in Proline-rich Ligand Recognition by the Src Homology 3 Domain of Abl*

    PubMed Central

    Palencia, Andres; Camara-Artigas, Ana; Pisabarro, M. Teresa; Martinez, Jose C.; Luque, Irene

    2010-01-01

    The interaction of Abl-Src homology 3 domain (SH3) with the high affinity peptide p41 is the most notable example of the inconsistency existing between the currently accepted description of SH3 complexes and their binding thermodynamic signature. We had previously hypothesized that the presence of interfacial water molecules is partially responsible for this thermodynamic behavior. We present here a thermodynamic, structural, and molecular dynamics simulation study of the interaction of p41 with Abl-SH3 and a set of mutants designed to alter the water-mediated interaction network. Our results provide a detailed description of the dynamic properties of the interfacial water molecules and a molecular interpretation of the thermodynamic effects elicited by the mutations in terms of the modulation of the water-mediated hydrogen bond network. In the light of these results, a new dual binding mechanism is proposed that provides a better description of proline-rich ligand recognition by Abl-SH3 and that has important implications for rational design. PMID:19906645

  19. Effects of water molecules on tribological behavior and property measurements in nano-indentation processes - a numerical analysis.

    PubMed

    Wang, Yachao; Shi, Jing

    2013-09-17

    Nano/micro-manufacturing under wet condition is an important consideration for various tool-based processes such as indentation, scratching, and machining. The existence of liquids adds complexity to the system, changes the tool/work interfacial condition, and affects material behaviors. For indentation, it may also affect material property measurements. However, little effort has been made to study this challenging issue at nano- or atomistic scale. In this study, we tackle this challenge by investigating nano-indentation processes submerged in water using the molecular dynamics (MD) simulation approach. Compared with dry indentation in which no water molecules are present, the existence of water molecules causes the increase of indentation force in initial penetration, but the decrease of indentation force in full penetration. It also reduces the sticking phenomenon between the work and tool atoms during indenter retraction, such that the indentation geometry can be better retained. Meanwhile, nano-indentation under wet condition exhibits the indentation size effect, while dry nano-indentation exhibits the reverse indentation size effect. The existence of water leads to higher computed hardness values at low indentation loads and a smaller value of Young's modulus. In addition, the friction along the tool/work interface is significantly reduced under wet indentation.

  20. Effects of water molecules on tribological behavior and property measurements in nano-indentation processes - a numerical analysis

    PubMed Central

    2013-01-01

    Nano/micro-manufacturing under wet condition is an important consideration for various tool-based processes such as indentation, scratching, and machining. The existence of liquids adds complexity to the system, changes the tool/work interfacial condition, and affects material behaviors. For indentation, it may also affect material property measurements. However, little effort has been made to study this challenging issue at nano- or atomistic scale. In this study, we tackle this challenge by investigating nano-indentation processes submerged in water using the molecular dynamics (MD) simulation approach. Compared with dry indentation in which no water molecules are present, the existence of water molecules causes the increase of indentation force in initial penetration, but the decrease of indentation force in full penetration. It also reduces the sticking phenomenon between the work and tool atoms during indenter retraction, such that the indentation geometry can be better retained. Meanwhile, nano-indentation under wet condition exhibits the indentation size effect, while dry nano-indentation exhibits the reverse indentation size effect. The existence of water leads to higher computed hardness values at low indentation loads and a smaller value of Young's modulus. In addition, the friction along the tool/work interface is significantly reduced under wet indentation. PMID:24044504

  1. Synthesis of CO and CO2 Molecules by UV Irradiation of Water Ice-covered Hydrogenated Carbon Grains

    NASA Astrophysics Data System (ADS)

    Mennella, V.; Baratta, G. A.; Palumbo, M. E.; Bergin, E. A.

    2006-06-01

    We present the results of UV irradiation with Lyα photons of carbon grains with a water ice cap at 11 K. Formation of CO and CO2 molecules takes place during irradiation. An estimation of the formation cross section of these molecules by Lyα photons has been obtained from the intensity increase of their infrared stretching bands as a function of the photon fluence. The fraction of carbon in the grains converted to CO and CO2 by UV photons is 0.06 and 0.05, respectively. The spectral profile of the CO stretching feature and that of the CO2 bending mode indicate a polar environment for these molecules. On the basis of the present laboratory results and those obtained in previous work on ion irradiation of similar samples, it has been possible to estimate the contribution of polar CO and CO2 produced on carbon grains by energetic processing to the observed column densities of these molecules for dense clouds whose visual extinction is known. A significant amount of polar CO and CO2 is produced through the mechanism we have studied. Furthermore, we have found that the laboratory profile of the bending band of CO2 produced on carbon grains is compatible with that observed toward the field star Elias 16.

  2. Selenium and Other Elements in Water and Adjacent Rock and Sediment of Toll Gate Creek, Aurora, Arapahoe County, Colorado, December 2003 through March 2004

    USGS Publications Warehouse

    Herring, J.R.; Walton-Day, Katherine

    2007-01-01

    Streamwater and solid samples (rock, unconsolidated sediment, stream sediment, and efflorescent material) in the Toll Gate Creek watershed, Colorado, were collected and analyzed for major and trace elements to determine trace-element concentrations and stream loads from December 2003 through March 2004, a period of seasonally low flow. Special emphasis was given to selenium (Se) concentrations because historic Se concentrations exceeded current (2004) stream standards. The goal of the project was to assess the distribution of Se concentration and loads in Toll Gate Creek and to determine the potential for rock and unconsolidated sediment in the basin to be sources of Se to the streamwater. Streamwater samples and discharge measurements were collected during December 2003 and March 2004 along Toll Gate Creek and its two primary tributaries - West Toll Gate Creek and East Toll Gate Creek. During both sampling periods, discharge ranged from 2.5 liters per second to 138 liters per second in the watershed. Discharge was greater in March 2004 than December 2003, but both periods represent low flow in Toll Gate Creek, and results of this study should not be extended to periods of higher flow. Discharge decreased moving downstream in East Toll Gate Creek but increased moving downstream along West Toll Gate Creek and the main stem of Toll Gate Creek, indicating that these two streams gain flow from ground water. Se concentrations in streamwater samples ranged from 7 to 70 micrograms per liter, were elevated in the upstream-most samples, and were greater than the State stream standard of 4.6 micrograms per liter. Se loads ranged from 6 grams per day to 250 grams per day, decreased in a downstream direction along East Toll Gate Creek, and increased in a downstream direction along West Toll Gate Creek and Toll Gate Creek. The largest Se-load increases occurred between two sampling locations on West Toll Gate Creek during both sampling periods and between the two sampling

  3. Structure and dynamics of high- and low-density water molecules in the liquid and supercooled regimes.

    PubMed

    Montes de Oca, Joan Manuel; Rodriguez Fris, J Ariel; Accordino, Sebastián R; Malaspina, David C; Appignanesi, Gustavo A

    2016-12-01

    By combining the local structure index with potential energy minimisations we study the local environment of the water molecules for a couple of water models, TIP5P-Ew and SPC/E, in order to characterise low- and high-density "species". Both models show a similar behaviour within the supercooled regime, with two clearly distinguishable populations of unstructured and structured molecules, the fraction of the latter increasing with supercooling. Additionally, for TIP5P-Ew, we find that the structured component vanishes quickly at the normal liquid regime (above the melting temperature). Thus, while SPC/E provides a fraction of structured molecules similar to that found in X-ray experiments, we show that TIP5P-Ew underestimates such value. Moreover, unlike SPC/E, we demonstrate that TIP5P-Ew does not follow the linear dependence of the logarithm of the structured fraction with inverse temperature, as predicted by the two-order parameter model. Finally, we link structure to dynamics by showing that there exists a strong correlation between structural fluctuation and dynamics in the supercooled state with spatial correlations in both static and dynamic quantities.

  4. Density Functional Theory Study of the Complexation of the Uranyl Dication with Anionic Phosphate Ligands with and without Water Molecules

    SciTech Connect

    Jackson, Virgil E.; Gutowski, Keith E.; Dixon, David A.

    2013-08-01

    The structures, vibrational frequencies and energetics of anhydrous and hydrated complexes of UO2 2+ with the phosphate anions H2PO4 -, HPO4 2-, and PO4 3- were predicted at the density functional theory (DFT) and MP2 molecular orbital theory levels as isolated gas phase species and in aqueous solution by using self-consistent reaction field (SCRF) calculations with different solvation models. The geometries and vibrational frequencies of the major binding modes for these complexes are compared to experiment where possible and good agreement is found. The uranyl moiety is nonlinear in many of the complexes, and the coordination number (CN) 5 in the equatorial plane is the predominant binding motif. The phosphates are found to bind in both monodentate and bidentate binding modes depending on the charge and the number of water molecules. The SCRF calculations were done with a variety of approaches, and different SCRF approaches were found to be optimal for different reaction types. The acidities of HxPO4 3-x in HxPO4 3-x(H2O)4, x = 0-3 complexes were calculated with different SCRF models and compared to experiment. Phosphate anions can displace water molecules from the first solvation shell at the uranyl exothermically. The addition of water molecules can cause the bonding of H2PO4 - and HPO4 2- to change from bidentate to monodentate exothermically while maintaining CN 5. The addition of water can generate monodentate structures capable of cross-linking to other uranyl phosphates to form the types of structures found in the solid state. [UO2(HPO4)(H2O)3] is predicted to be a strong base in the gas phase and in aqueous solution. It is predicted to be a much weaker acid than H3PO4 in the gas phase and in solution.

  5. Relationships between membrane water molecules and Patman equilibration kinetics at temperatures far above the phosphatidylcholine melting point.

    PubMed

    Vaughn, Alexandra R; Bell, Thomas A; Gibbons, Elizabeth; Askew, Caitlin; Franchino, Hannabeth; Hirsche, Kelsey; Kemsley, Linea; Melchor, Stephanie; Moulton, Emma; Schwab, Morgan; Nelson, Jennifer; Bell, John D

    2015-04-01

    The naphthalene-based fluorescent probes Patman and Laurdan detect bilayer polarity at the level of the phospholipid glycerol backbone. This polarity increases with temperature in the liquid-crystalline phase of phosphatidylcholines and was observed even 90°C above the melting temperature. This study explores mechanisms associated with this phenomenon. Measurements of probe anisotropy and experiments conducted at 1M NaCl or KCl (to reduce water permittivity) revealed that this effect represents interactions of water molecules with the probes without proportional increases in probe mobility. Furthermore, comparison of emission spectra to Monte Carlo simulations indicated that the increased polarity represents elevation in probe access to water molecules rather than increased mobility of relevant bilayer waters. Equilibration of these probes with the membrane involves at least two steps which were distinguished by the membrane microenvironment reported by the probe. The difference in those microenvironments also changed with temperature in the liquid-crystalline phase in that the equilibrium state was less polar than the initial environment detected by Patman at temperatures near the melting point, more polar at higher temperatures, and again less polar as temperature was raised further. Laurdan also displayed this level of complexity during equilibration, although the relationship to temperature differed quantitatively from that experienced by Patman. This kinetic approach provides a novel way to study in molecular detail basic principles of what happens to the membrane environment around an individual amphipathic molecule as it penetrates the bilayer. Moreover, it provides evidence of unexpected and interesting membrane behaviors far from the phase transition.

  6. Chemical-quality reconnaissance of the water and surficial bed material in the Delaware River estuary and adjacent New Jersey tributaries, 1980-81

    USGS Publications Warehouse

    Hochreiter, Joseph J.

    1982-01-01

    This report presents chemical-quality data collected from May 1980 to January 1981 at several locations within the Delaware River estuary and selected New Jersey tributaries. Samples of surface water were analyzed Environmental Protection Agency ' priority pollutants, ' including acid extractable, base/neutral extractable and volatile organic compounds, in addition to selected dissolved inorganic constituents. Surficial bed material at selected locations was examined for trace metals, insecticides, polychlorinated biphenyls, and base/neutral extractable organic compounds. Trace levels (1-50 micrograms per liter) of purgeable organic compounds, particularly those associated with the occurrence of hydrocarbons, were found in about 60% of the water samples taken. DDT, DDD, DDE, PCB 's and chlordane are present in most surficial bed material samples. Diazinon was the only organophosphorous insecticide detected in the study (1.6 micrograms per kilogram at one location). High values for select trace metals in bed material were discovered at two locations. Of the 10 sites sampled, the surficial bed material containing the most contamination was found along one cross section of Raccoon Creek at Bridgeport. An additional analysis of Raccoon Creek revealed bed material containing toluene, oil and grease, and trace quantities of 15 base/neutral extractable organic compounds, including polynuclear aromatic hydrocarbons, phthalate esters, and chlorinated benzenes.

  7. Potential effects of groundwater pumping on water levels, phreatophytes, and spring discharges in Spring and Snake Valleys, White Pine County, Nevada, and adjacent areas in Nevada and Utah

    USGS Publications Warehouse

    Halford, Keith J.; Plume, Russell W.

    2011-01-01

    Assessing hydrologic effects of developing groundwater supplies in Snake Valley required numerical, groundwater-flow models to estimate the timing and magnitude of capture from streams, springs, wetlands, and phreatophytes. Estimating general water-table decline also required groundwater simulation. The hydraulic conductivity of basin fill and transmissivity of basement-rock distributions in Spring and Snake Valleys were refined by calibrating a steady state, three-dimensional, MODFLOW model of the carbonate-rock province to predevelopment conditions. Hydraulic properties and boundary conditions were defined primarily from the Regional Aquifer-System Analysis (RASA) model except in Spring and Snake Valleys. This locally refined model was referred to as the Great Basin National Park calibration (GBNP-C) model. Groundwater discharges from phreatophyte areas and springs in Spring and Snake Valleys were simulated as specified discharges in the GBNP-C model. These discharges equaled mapped rates and measured discharges, respectively. Recharge, hydraulic conductivity, and transmissivity were distributed throughout Spring and Snake Valleys with pilot points and interpolated to model cells with kriging in geologically similar areas. Transmissivity of the basement rocks was estimated because thickness is correlated poorly with transmissivity. Transmissivity estimates were constrained by aquifer-test results in basin-fill and carbonate-rock aquifers. Recharge, hydraulic conductivity, and transmissivity distributions of the GBNP-C model were estimated by minimizing a weighted composite, sum-of-squares objective function that included measurement and Tikhonov regularization observations. Tikhonov regularization observations were equations that defined preferred relations between the pilot points. Measured water levels, water levels that were simulated with RASA, depth-to-water beneath distributed groundwater and spring discharges, land-surface altitudes, spring discharge at

  8. Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks

    NASA Astrophysics Data System (ADS)

    Byun, Jeehye; Patel, Hasmukh A.; Thirion, Damien; Yavuz, Cafer T.

    2016-11-01

    Molecular architecture in nanoscale spaces can lead to selective chemical interactions and separation of species with similar sizes and functionality. Substrate specific sorbent chemistry is well known through highly crystalline ordered structures such as zeolites, metal organic frameworks and widely available nanoporous carbons. Size and charge-dependent separation of aqueous molecular contaminants, on the contrary, have not been adequately developed. Here we report a charge-specific size-dependent separation of water-soluble molecules through an ultra-microporous polymeric network that features fluorines as the predominant surface functional groups. Treatment of similarly sized organic molecules with and without charges shows that fluorine interacts with charges favourably. Control experiments using similarly constructed frameworks with or without fluorines verify the fluorine-cation interactions. Lack of a σ-hole for fluorine atoms is suggested to be responsible for this distinct property, and future applications of this discovery, such as desalination and mixed matrix membranes, may be expected to follow.

  9. Body condition of the deep water demersal resources at two adjacent oligotrophic areas of the western Mediterranean and the influence of the environmental features

    NASA Astrophysics Data System (ADS)

    Rueda, L.; Moranta, J.; Abelló, P.; Balbín, R.; Barberá, C.; Fernández de Puelles, M. L.; Olivar, M. P.; Ordines, F.; Ramón, M.; Torres, A. P.; Valls, M.; Massutí, E.

    2014-10-01

    Body condition indices not only are often used as reliable indicators of the nutritional status of individuals but also can they be utilized to provide insights regarding food availability and habitat quality. The aim of this study was to evaluate the connection between the body condition of the demersal species and the environmental features in the water column (i.e. the hydrographic conditions and the potential trophic resources) in two proximate areas, the north and south regions of the Balearic Islands (western Mediterranean), viz., the Balearic sub-basin (BsB) and the Algerian sub-basin (AsB), respectively, with different geomorphological and hydrodynamic features. Body condition indices were calculated for individuals of 21 demersal species including 11 teleosts, 4 elasmobranchs, 3 cephalopods and 3 crustaceans, which represented > 70-77% of the deep water resources, captured by bottom trawling. The morphometric indices, viz., Relative Condition Index (Kn) and Standardised Residuals (SR) from the length-weight relationship, were used. The results for each one of the 21 species indicated a significantly better condition in terms of Kn and SR in the BsB, for 7 and 9 species, respectively. In addition, a general model, including the 21 species together, showed better body condition in the BsB, and during the summer. The spatial and temporal differences in the body condition are discussed in the context of the environmental variables characterising both the study areas, which showed significant variations, for some of the hydrographic features (chlorophyll a, dissolved oxygen, salinity, potential density and temperature), as well as for some of the potential trophic resources (mesopelagic and epibenthic fauna). These findings suggest an environmental effect on the body condition of the deep-water resources in the Balearic Islands, one of the most oligotrophic areas of the western Mediterranean, and reveal more suitable environmental conditions for these species

  10. Performance Characterization of the Free Molecule Micro-Resistojet Utilizing Water Propellant (Preprint)

    DTIC Science & Technology

    2007-05-24

    missions are currently being conceived as a result of the development of micro - and nano - technologies. The general agreement in the spacecraft...Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Performance Characterization of the Free Molecule Micro -Resistojet...Submitted for publication in the Journal of Spacecraft and Rockets. 14. ABSTRACT Advances in micro -technology manufacturing and capability have led

  11. Engineering and Environmental Study of DDT Contamination of Huntsville Spring Branch, Indian Creek, and Adjacent Lands and Waters, Wheeler Reservoir, Alabama. Volume 3. Appendices IV-VI.

    DTIC Science & Technology

    1980-11-01

    SEDIMENTS 1-14 4.5 DEGRADATION BY SPECIFIC MICROBIAL POPULATIONS 1-15 4.6 DEGRADATION BY FUNGI 1-15 4.7 DEGRADATION BY ALGAE 1-15 4.8 DEGRADATION BY A...AQUATIC VERTEBRATES 1-46 5.4 BIRDS 1-56 5.5 MAMMALS 1-59 5.6 ALGAE AND FUNGI 1-59 6.0 EPA AMBIENT WATER QUALITY CRITERIA FOR DDT 1-59 7.0 FDA REGULATIONS...sp. 11,561,323 10,690,680 Oscillatoria sp. 546,683 135,503 Spirulina sp. 17,133 20,248 Euglenophyta Euglena sp. 74,760 404,950 Phacus sp. 3,115 3,115

  12. Determination of selected pesticides in water samples adjacent to agricultural fields and removal of organophosphorus insecticide chlorpyrifos using soil bacterial isolates

    NASA Astrophysics Data System (ADS)

    Hossain, M. S.; Chowdhury, M. Alamgir Zaman; Pramanik, Md. Kamruzzaman; Rahman, M. A.; Fakhruddin, A. N. M.; Alam, M. Khorshed

    2015-06-01

    The use of pesticide for crops leads to serious environmental pollution, therefore, it is essential to monitor and develop approaches to remove pesticide from contaminated environment. In this study, water samples were collected to monitor pesticide residues, and degradation of chlorpyrifos was also performed using soil bacteria. Identification of pesticide residues and determination of their levels were performed by high-performance liquid chromatography with photodiode array detector. Among 12 samples, 10 samples were found contaminated with pesticides. Chlorpyrifos was detected in four tested samples and concentrations ranged from 3.27 to 9.31 μg/l whereas fenitrothion ranging from (Below Detection Limit, <0.1 μg/l) to 33.41 μg/l in the tested samples. Parathion was found in two tested samples at the concentration of 0.73 and 6.23 μg/l. None of the tested samples was found contaminated with Methoxychlor, DDT and Ethion. Three soil bacterial isolates, Pseudomonas peli BG1, Burkholderia caryophylli BG4 and Brevundimonas diminuta PD6 degraded chlorpyrifos completely in 8, 10 and 10 days, respectively, when 20 mg/l chlorpyrifos was supplied as sole source of carbon. Whereas, BG1, BG4 and PD6 took 14, 16 and 16 days, respectively, for complete removal of 50 mg/l chlorpyrifos. Chlorpyrifos degradation rates were found maximum by all three isolates at 2nd day of incubation for both tested concentrations. The results of the present study suggest the need for regular monitoring of pesticide residues in water, to protect the aquatic environment. Chlorpyrifos degrading bacterial isolates can be used to clean up environmental samples contaminated with the organophosphate pesticides.

  13. Formation of CO and CO2 Molecules by Ion Irradiation of Water Ice-covered Hydrogenated Carbon Grains

    NASA Astrophysics Data System (ADS)

    Mennella, V.; Palumbo, M. E.; Baratta, G. A.

    2004-11-01

    We present the results of experiments aimed at studying the influence of the type of grain on the chemical composition of the ice mantles during energetic processing under simulated dense medium conditions. Formation of CO and CO2 molecules occurs when hydrogenated carbon grains with a water ice cap are irradiated with 30 keV He+ ions at low temperature. The fraction of carbon in the grains converted to CO and CO2 by ions is at least 0.03 and 0.02, respectively. An estimation of the formation cross section of these molecules by 30 keV He+ ions has been derived from the intensity increase of their infrared stretching bands as a function of the ion fluence. On the basis of the laboratory results, it has been possible to evaluate the contribution of CO and CO2 produced on carbon grain by cosmic rays to the observed column densities of these molecules for dense clouds whose visual extinction is known. The mechanism we have studied does not dominate other CO2 formation processes; however, its contribution is in addition to other processes occurring on ice mantles. The spectral profile and the contribution to the observed column densities make solid CO formed by cosmic-ray irradiation of ice-layered carbon grains a good candidate for the red component of the interstellar CO stretching feature, which is generally attributed to CO mixed in with water ice. As a consequence of the formation of CO and CO2 molecules on carbon grains, a slow chemical erosion of the particles takes place.

  14. An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket.

    PubMed

    Debler, Erik W; Müller, Roger; Hilvert, Donald; Wilson, Ian A

    2009-11-03

    Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp(H35) and Glu(L34) to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu(L34) to alanine mutant, leads to an impressive 10(9)-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.

  15. Binding site identification and role of permanent water molecule of PIM-3 kinase: A molecular dynamics study.

    PubMed

    Ul-Haq, Zaheer; Gul, Sana; Usmani, Saman; Wadood, Abdul; Khan, Waqasuddin

    2015-11-01

    The kinome is a protein kinase complement of the human genome, categorized as serine/threonine and tyrosine kinases. These kinases catalyze phosphorylation reaction by using ATP as phosphoryl donor. Proviral Integration Site for Moloney Murine Leukemia Virus (PIM) kinase encodes serine/threonine protein kinases that recognized as proto-oncogene, responsible for rapid growth of cancerous cells. It is implicated in cell survival and function via cell cycle progression and its metabolism. PIM-3, sub-member of PIM kinases is a proto-oncogene, its overexpression inhibits apoptosis, and results in progression of hepatocellular carcinoma. PIM-3 is considered as a promising drug target but attempts to develop its specific inhibitors is slowed down due to the lack of 3D structure by any experimental technique. In silico techniques generally facilitate scientist to explore hidden structural features in order to improve drug discovery. In the present study, homology modeling, molecular docking and MD simulation techniques were utilized to explore the structure and dynamics of PIM-3 kinase. Induction of water molecules during molecular docking simulation explored differences in the hinge region between PIM-1 and PIM-3 kinases that may be responsible for specificity. Furthermore, role of water molecules in the active site was also explored via radial distribution function (RDF) after a 10 ns molecular dynamics (MD) simulations. Generated RDF plots exhibited the importance of water for inhibitor binding through their bridging capability that links the ligand with binding site residues.

  16. An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket

    SciTech Connect

    Debler, Erik W.; Müller, Roger; Hilvert, Donald; Wilson, Ian A.

    2009-12-01

    Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp{sup H35} and Glu{sup L34} to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu{sup L34} to alanine mutant, leads to an impressive 10{sup 9}-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.

  17. Computational study of the interaction of indole-like molecules with water and hydrogen sulfide

    NASA Astrophysics Data System (ADS)

    Cabaleiro-Lago, Enrique M.; Rodríguez-Otero, Jesús; Peña-Gallego, Ángeles

    2011-10-01

    The characteristics of the interaction between water and hydrogen sulfide with indole and a series of analogs obtained by substituting the NH group of indole by different heteroatoms have been studied by means of ab initio calculations. In all cases, minima were found corresponding to structures where water and hydrogen sulfide interact by means of X-H...π contacts. The interaction energies for all these π complexes are quite similar, spanning from -13.5 to -18.8 kJ/mol, and exhibiting the stability sequence NH > CH2 ≈ PH > Se ≈ S > O, for both water and hydrogen sulfide. Though interaction energies are similar, hydrogen sulfide complexes are slightly favored over their water counterparts when interacting with the π cloud. σ-Type complexes were also considered for the systems studied, but only in the case of water complexes this kind of complexes is relevant. Only for complexes formed by water and indole, a significantly more stable σ-type complex was found with an interaction energy amounting to -23.6 kJ/mol. Oxygen and phosphorous derivatives also form σ-type complexes of similar stability as that observed for π ones. Despite the similar interaction energies exhibited by complexes with water and hydrogen sulfide, the nature of the interaction is very different. For π complexes with water the main contributions to the interaction energy are electrostatic and dispersive contributing with similar amounts, though slightly more from electrostatics. On the contrary, in hydrogen sulfide complexes dispersion is by far the main stabilizing contribution. For the σ-type complexes, the interaction is clearly dominated by the electrostatic contribution, especially in the indole-water complex.

  18. DFT studies of carbohydrate solvation: II. MD-DFTr of a super-molecule complex of glucose, explicit waters, and an implicit solvent (COSMO)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MD-DFTr studies are carried out on the super-molecule solvated complexes of glucose described in paper I. Included were ten explicit water molecules and an implicit solvation model, COSMO, superimposed upon the complex. Starting configurations were taken from DFTr optimized complexes resulting from ...

  19. On the connection between the Koppel-Young and the Nelkin Models for thermal neutron scattering in water molecules

    SciTech Connect

    Markovic, M.I.

    1982-10-01

    A critical analysis of the Koppel-Young model is presented and compared with Nelkin's model and their equivalence is asserted. It is shown that the only distinction between the two models is in the orientational averaging of the rotational-vibrational intermedial scattering function. Based on total cross sections, the Krieger-Nelkin orientation averaging has been confirmed to give excellent agreement with the Koppel-Young orientation averaging. However, significant quasi-periodical differences are observed when calculating differential cross sections. As a result of these insights, a new unified model is proposed for microdynamics of water molecules.

  20. Product distributions and rate constants for ion-molecule reactions in water, hydrogen sulfide, ammonia, and methane

    NASA Technical Reports Server (NTRS)

    Huntress, W. T., Jr.; Pinizzotto, R. F., Jr.

    1973-01-01

    The thermal energy, bimolecular ion-molecule reactions occurring in gaseous water, hydrogen sulfide, ammonia, and methane have been identified and their rate constants determined using ion cyclotron resonance methods. Absolute rate constants were determined for the disappearance of the primary ions by using the trapped ion method, and product distributions were determined for these reactions by using the cyclotron ejection method. Previous measurements are reviewed and compared with the results using the present methods. The relative rate constants for hydrogen-atom abstraction, proton transfer, and charge transfer are also determined for reactions of the parent ions.

  1. Inter-annual variability in the biosphere-atmosphere exchange of carbon dioxide and water vapor in adjacent pine and hardwood forests: links to drought, disturbance, and seasonality

    NASA Astrophysics Data System (ADS)

    Novick, K. A.; Ward, E. J.; Oishi, A. C.; Stoy, P. C.

    2012-12-01

    Understanding the variation in long-term biosphere-atmosphere fluxes of carbon dioxide and water vapor is necessary to characterize the benefits and services of terrestrial ecosystems, including the highly productive forests of the Southeastern United States. This study quantifies flux variability at inter-annual times scales using eight-year eddy covariance records from two co-located ecosystems in the Duke Forest (North Carolina, USA): a hardwood deciduous forest (HW) and a pine plantation (PP), which together represent the dominant forest types in the region. When averaged across the study period, annual net ecosystem exchange of CO2 (NEE) was similar in PP and HW (NEE = -560 and -520 g C m-2 y-1 in PP and HW, respectively). Variation in annual NEE was high in both ecosystems, but higher in the pine site (CV = 0.38) as compared to the hardwood site (CV = 0.23). Gross ecosystem productivity (GEP) and ecosystem respiration (RE), which together represent the primary components of NEE, were not necessarily more variable in the pine site; however, the coupling between annual GEP and RE was weaker in PP as compared to HW, contributing to higher overall variability in PP NEE. Our results identify at least two factors contributing to this decoupling: 1) an ice storm event, which reduced PP GEP while increasing or having no effect on PP RE, and 2) two severe drought events, which cause large reductions in PP GEP but not RE. Additionally, in both ecosystems, variability in GEP and NEE is strongly related to the length of the active season (r2 = 0.60 - 0.93), a variable reflecting the seasonality of carbon assimilation that is largely independent from patterns of leaf area development.

  2. 52. EASTSIDE PLANT: GENERAL VIEW OF GOVERNOR ADJACENT TO GENERATOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. EASTSIDE PLANT: GENERAL VIEW OF GOVERNOR ADJACENT TO GENERATOR - American Falls Water, Power & Light Company, Island Power Plant, Snake River, below American Falls Dam, American Falls, Power County, ID

  3. 72. View of reservoir adjacent to south wall of blowing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. View of reservoir adjacent to south wall of blowing engine house where water from furnaces was allowed to cool. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  5. GYY4137, a novel water-soluble, H2S-releasing molecule.

    PubMed

    Rose, Peter; Dymock, Brian W; Moore, Philip K

    2015-01-01

    Hydrogen sulfide (H2S) is now recognized as the so called "third gasotransmitter" taking its place alongside nitric oxide and carbon monoxide. In recent years, H2S has been reported to exhibit a diverse range of pharmacological effects in biological systems. Much of this evidence is derived from a combination of conventional pharmacological and genetic approaches coupled with the use of chemical compounds such as sodium hydrosulfide, a rapid H2S releasing donor. Developments in the design of new drug entities which attempt to take into account physicochemical properties, targeting to specific cellular organelles, triggering of H2S release upon specific chemical reactions in the cell, and controlling the release of H2S over extended periods of time have been described. For most of these molecules, little or no work has been conducted to determine their biological activity or possible therapeutic effects. It is therefore not clear whether such molecules have therapeutic potential which highlights the need for further in vivo studies. One exception to the general rule is GYY4137 (morpholin-4-ium 4-methoxyphenyl(morpholino) phosphinodithioate), a slow releasing H2S donor, which has been evaluated for activity in a range of pharmacological models both in vitro and in vivo. GYY4137 was first reported to release H2S and exhibit vasodilator activity over 5 years ago and, to date, GYY4137 is becoming increasingly employed as a pharmacological "tool" to explore the biological functions of H2S.

  6. The key role of meteorites in the formation of relevant prebiotic molecules in a formamide/water environment

    PubMed Central

    Rotelli, Luca; Trigo-Rodríguez, Josep M.; Moyano-Cambero, Carles E.; Carota, Eleonora; Botta, Lorenzo; Di Mauro, Ernesto; Saladino, Raffaele

    2016-01-01

    We show that carbonaceous chondrite meteorites actively and selectively catalyze the formation of relevant prebiotic molecules from formamide in aqueous media. Specific catalytic behaviours are observed, depending on the origin and composition of the chondrites and on the type of water present in the system (activity: thermal > seawater > pure). We report the one-pot synthesis of all the natural nucleobases, of aminoacids and of eight carboxylic acids (forming, from pyruvic acid to citric acid, a continuous series encompassing a large part of the extant Krebs cycle). These data shape a general prebiotic scenario consisting of carbonaceous meteorites acting as catalysts and of a volcanic-like environment providing heat, thermal waters and formamide. This scenario also applies to the other solar system locations that experienced rich delivery of carbonaceous materials, and whose physical-chemical conditions could have allowed chemical evolution. PMID:27958316

  7. The key role of meteorites in the formation of relevant prebiotic molecules in a formamide/water environment

    NASA Astrophysics Data System (ADS)

    Rotelli, Luca; Trigo-Rodríguez, Josep M.; Moyano-Cambero, Carles E.; Carota, Eleonora; Botta, Lorenzo; di Mauro, Ernesto; Saladino, Raffaele

    2016-12-01

    We show that carbonaceous chondrite meteorites actively and selectively catalyze the formation of relevant prebiotic molecules from formamide in aqueous media. Specific catalytic behaviours are observed, depending on the origin and composition of the chondrites and on the type of water present in the system (activity: thermal > seawater > pure). We report the one-pot synthesis of all the natural nucleobases, of aminoacids and of eight carboxylic acids (forming, from pyruvic acid to citric acid, a continuous series encompassing a large part of the extant Krebs cycle). These data shape a general prebiotic scenario consisting of carbonaceous meteorites acting as catalysts and of a volcanic-like environment providing heat, thermal waters and formamide. This scenario also applies to the other solar system locations that experienced rich delivery of carbonaceous materials, and whose physical-chemical conditions could have allowed chemical evolution.

  8. Premelted liquid water in frozen soils and its interaction with bio-molecules

    NASA Astrophysics Data System (ADS)

    Hansen-Goos, H.; Wettlaufer, J. S.

    2011-12-01

    While liquid water in bulk is unstable on the surface of Mars, there is a possibility for the persistence of thin films of liquid water in the Martian regolith as a result of interfacial forces between the interstitial ice and the soil grains even below the bulk melting temperature. This is referred to as premelting. We present a calculation of the liquid fraction of frozen soils which takes into account premelting in combination with the effect of ionic impurities and the curvature induced freezing point depression (Gibbs-Thomson effect). We introduce a revised density functional theory which accurately treats a simple model for confined liquid water. We use the theory to study how biological matter (antifreeze proteins in particular) inside a narrow liquid cavity in ice interacts with the surrounding ice-water interface. Because in this case the interface is concave and hence the Gibbs-Thomson effect is antagonistic to the liquid phase, the protein-ice interaction is responsible for the persistence of liquid water.

  9. Proposed Photosynthesis Method for Producing Hydrogen from Dissociated Water Molecules Using Incident Near-Infrared Light

    NASA Astrophysics Data System (ADS)

    Li, Xingxing; Li, Zhenyu; Yang, Jinlong

    2014-01-01

    Highly efficient solar energy utilization is very desirable in photocatalytic water splitting. However, until now, the infrared part of the solar spectrum, which constitutes almost half of the solar energy, has not been used, resulting in significant loss in the efficiency of solar energy utilization. Here, we propose a new mechanism for water splitting in which near-infrared light can be used to produce hydrogen. This ability is a result of the unique electronic structure of the photocatalyst, in which the valence band and conduction band are distributed on two opposite surfaces with a large electrostatic potential difference produced by the intrinsic dipole of the photocatalyst. This surface potential difference, acting as an auxiliary booster for photoexcited electrons, can effectively reduce the photocatalyst's band gap required for water splitting in the infrared region. Our electronic structure and optical property calculations on a surface-functionalized hexagonal boron-nitride bilayer confirm the existence of such photocatalysts and verify the reaction mechanism.

  10. What interactions can distort the orientational distribution of interfacial water molecules as probed by second harmonic and sum frequency generation?

    PubMed

    de Beer, Alex G F; Roke, Sylvie

    2016-07-28

    Aqueous interfaces are omnipresent in nature. Nonlinear optical methods such as second harmonic and sum frequency generation (SHG/SFG) are valuable techniques to access molecular level information from these interfaces. In the interpretation of SHG and SFG data for both scattering and reflection mode experiments, the relation between the second-order hyperpolarizability tensor β(2), a molecular property, and the surface second-order susceptibility χ(2), a surface averaged property, plays a central role. To correctly describe the molecular details of the interface, it needs to be determined how molecules are oriented, and what the influence is of interfacial electrostatic fields and H-bonding on the orientational distribution. Here, we revisit the relations between β(2) and χ(2) and show, by means of a Boltzmann average, that significant energy differences are needed to generate measurable changes in the molecular orientational distribution at the interface. In practice, H-bonding and surface pressure such as applied in a Langmuir trough can be strong enough to alter the shape of the orientational distribution function of water. In contrast, electrostatic fields, such as those present in the Stern layer, will not have a significant impact on the shape of the orientational distribution function of water molecules.

  11. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules

    PubMed Central

    Davidge, Kelly S; Singh, Sandip; Bowman, Lesley AH; Tinajero-Trejo, Mariana; Carballal, Sebastián; Radi, Rafael; Poole, Robert K; Dikshit, Kanak; Estrin, Dario A; Marti, Marcelo A; Boechi, Leonardo

    2015-01-01

    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 O 2 and •NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify •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, •NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. 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. PMID:26478812

  12. The effects of metabolite molecules produced by drinking water-isolated bacteria on their single and multispecies biofilms.

    PubMed

    Simões, Lúcia Chaves; Simões, Manuel; Vieira, Maria João

    2011-08-01

    The elucidation of the mechanisms by which diverse species survive and interact in drinking water (DW) biofilm communities may allow the identification of new biofilm control strategies. The purpose of the present study was to investigate the effects of metabolite molecules produced by bacteria isolated from DW on biofilm formation. Six opportunistic bacteria, viz. Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp. isolated from a drinking water distribution systems (DWDS) were used to form single and multispecies biofilms in the presence and absence of crude cell-free supernatants produced by the partner bacteria. Biofilms were characterized in terms of mass and metabolic activity. Additionally, several physiological aspects regulating interspecies interactions (sessile growth rates, antimicrobial activity of cell-free supernatants, and production of iron chelators) were studied to identify bacterial species with biocontrol potential in DWDS. Biofilms of Methylobacterium sp. had the highest growth rate and M. mucogenicum biofilms the lowest. Only B. cepacia was able to produce extracellular iron-chelating molecules. A. calcoaceticus, B. cepacia, Methylobacterium sp. and M. mucogenicum biofilms were strongly inhibited by crude cell-free supernatants from the other bacteria. The crude cell-free supernatants of M. mucogenicum and S. capsulata demonstrated a high potential for inhibiting the growth of counterpart biofilms. Multispecies biofilm formation was strongly inhibited in the absence of A. calcoaceticus. Only crude cell-free supernatants produced by B. cepacia and A. calcoaceticus had no inhibitory effects on multispecies biofilm formation, while metabolite molecules of M. mucogenicum showed the most significant biocontrol potential.

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

    NASA Astrophysics Data System (ADS)

    Dutta, Bipan; De, Rina; Chowdhury, Joydeep

    2015-12-01

    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.

  14. Structure and energetics of model amphiphilic molecules at the water liquid-vapor interface - A molecular dynamics study

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Benjamin, Ilan

    1993-01-01

    A molecular dynamics study of adsorption of p-n-pentylphenol at infinite dilution at the water liquid-vapor interface is reported. The calculated free energy of adsorption is -8.8 +/- 0.7 kcal/mol, in good agreement with the experimental value of -7.3 kcal/mol. The transition between the interfacial region and the bulk solution is sharp and well-defined by energetic, conformational, and orientational criteria. At the water surface, the phenol head group is mostly immersed in aqueous solvent. The most frequent orientation of the hydrocarbon tail is parallel to the interface, due to dispersion interactions with the water surface. This arrangement of the phenol ring and the alkyl chain requires that the chain exhibits a kink. As the polar head group is being moved into the solvent, the chain length increases and the tail becomes increasingly aligned toward the surface normal, such that the nonpolar part of the molecule exposed to water is minimized. The same effect was achieved when phenol was replaced by a more polar head group, phenolate.

  15. Geology and ground-water features of salt springs, seeps, and plains in the Arkansas and Red River basins of western Oklahoma and adjacent parts of Kansas and Texas

    USGS Publications Warehouse

    Ward, P.E.

    1963-01-01

    The salt springs, seeps, and plains described in this report are in the Arkansas and Red River basins in western Oklahoma and adjacent areas in Kansas and Texas. The springs and seeps contribute significantly to the generally poor water quality of the rivers by bringing salt (HaCI) to the surface at an estimated daily rate of more than 8,000 tons. The region investigated is characterized by low hills and rolling plains. Many of the rivers are eroded 100 feet or more below the .surrounding upland surface and in places the valleys are bordered by steep bluffs. The alluvial plains of the major rivers are wide and the river channels are shallow and unstable. The flow of many surface streams is intermittent, especially in the western part of the area. All the natural salt-contributing areas studied are within the outcrop area of rocks of Permian age. The Permian rocks, commonly termed red beds, are composed principally of red and gray gypsiferous shale, siltstone, sandstone, gypsum, anhydrite, and dolomite. Many of the formations contain halite in the subsurface. The halite occurs mostly as discontinuous lenses in shale, although some of the thicker, more massive beds are extensive. It underlies the entire region studied at depths ranging from about 30 feet to more than 2,000 feet. The salt and associated strata show evidence of extensive removal of salt through solution by ground water. Although the salt generally occurs in relatively impervious shale small joints and fractures ,allow the passage of small quantities of water which dissolves the salt. Salt water occurs in the report area at depths ranging from less than 100 feet to more than 1,000 feet. Salt water occurs both as meteoric and connate, but the water emerging as salt springs is meteoric. Tritium analyses show that the age of the water from several springs is less than 20 years. The salt springs, seeps, and plains are confined to 13 local areas. The flow of the springs and seeps is small, but the chloride

  16. Determination of the optimal position of adjacent proton-donor centers for the activation or inhibition of peptide bond formation--a computational model study.

    PubMed

    Rangelov, Miroslav A; Petrova, Galina P; Yomtova, Vihra M; Vayssilov, Georgi N

    2011-09-01

    The study reports a computational analysis of the influence of proton donor group adjacent to the reaction center during ester ammonolysis of an acylated diol as a model reaction for peptide bond formation. This analysis was performed using catalytic maps constructed after a detailed scanning of the available space around the reaction centers in different transition states, a water molecule acting as a typical proton donor. The calculations suggest that an adjacent proton donor center can reduce the activation barrier of the rate determining transition states by up to 7.2 kcal/mol, while no inhibition of the reaction can be achieved by such a group.

  17. Dissociative electron attachment to water molecule: Experimental study of the dissociation dynamics

    NASA Astrophysics Data System (ADS)

    Adaniya, H.; Rudek, B.; Osipov, T.; Weber, T.; Lee, S.; Hertlein, M.; Schoeffler, M.; Prior, M.; Belkacem, A.

    2009-11-01

    The dynamics of the dissociative electron attachment(DEA)to water(H2O, D2O)via three resonances, 2B1, 2A1, 2B2, are investigated using the modified Coltrims spectrometer. The angular dependence of the negative ion shows unique distribution in each resonance indicating the three resonances involve different dissociation dynamics. The energy distribution among the fragments shows considerable amount of three body break.

  18. Organic Molecules and Water in the Inner Disks of T Tauri Stars

    DTIC Science & Technology

    2011-05-11

    water emission properties in the full Spitzer spectrum (but see Section 4.2.2). By focusing on this wavelength region we can also optimize the...cores and comets are from references given in the text . (A color version of this figure is available in the online journal.) error bars corresponds to...because comets are made of icy material that was originally present in the Jupiter– Saturn region and in the outer solar nebula (the Kuiper Belt) during

  19. Ordering of protein and water molecules at their interfaces with chitin nano-crystals.

    PubMed

    Valverde Serrano, Clara; Leemreize, Hanna; Bar-On, Benny; Barth, Friedrich G; Fratzl, Peter; Zolotoyabko, Emil; Politi, Yael

    2016-02-01

    Synchrotron X-ray diffraction was applied to study the structure of biogenic α-chitin crystals composing the tendon of the spider Cupiennius salei. Measurements were carried out on pristine chitin crystals stabilized by proteins and water, as well as after their deproteinization and dehydration. We found substantial shifts (up to Δq/q=9% in the wave vector in q-space) in the (020) diffraction peak position between intact and purified chitin samples. However, chitin lattice parameters extracted from the set of reflections (hkl), which did not contain the (020)-reflection, showed no systematic variation between the pristine and the processed samples. The observed shifts in the (020) peak position are discussed in terms of the ordering-induced modulation of the protein and water electron density near the surface of the ultra-thin chitin fibrils due to strong protein/chitin and water/chitin interactions. The extracted modulation periods can be used as a quantitative parameter characterizing the interaction length.

  20. Depth profiles of hydrogen bound water molecule types and their relation to lipid and protein interaction in the human stratum corneum in vivo.

    PubMed

    Choe, ChunSik; Lademann, Jürgen; Darvin, Maxim E

    2016-11-21

    Confocal Raman microscopy has been used to measure depth-dependent profiles of human SC in vivo in the high wavenumber (HWN) region. In order to keep the linearity of HWN region boundaries and to not remove an informative signal from Raman spectra, a new baseline subtraction procedure has been introduced. After baseline subtraction, the HWN spectrum was deconvoluted using 10 Gaussian functions with individual chemical meanings. The results show that the hydrogen bound water molecule types contributed differently to the water diffusion process in the SC. The most concentrated double donor-double acceptor (DDAA) and single donor-single acceptor (DA) water molecule types in the SC represent more than 90% of the SC's water and mostly contribute to the water flux in the skin. Single donor-double acceptor (DAA) and weakly-bound water molecule types represent less than 10% of the SC's water content. The most tightly hydrogen bound water molecule type, DAA, reaches its maximum concentration near the skin surface and does not take part in the water diffusion process via the SC. The results show that the hydrogen bonding state of water (DA/DDAA water molecule type ratio) reaches its maximum at the depth of approx. 30% of the SC thickness, which correlates well with the maximum lateral packing order of intercellular lipids (ICL) and the natural moisturizing factor (NMF), and does not coincide with the folding/unfolding state of keratin. The NMF's contribution to the bonding of water in the SC is supposed to dominate over that of ICL.

  1. Assessments of aquifer sensitivity on Navajo Nation and adjacent lands and ground-water vulnerability to pesticide contamination on the Navajo Indian Irrigation Project, Arizona, New Mexico, and Utah

    USGS Publications Warehouse

    Blanchard, Paul J.

    2002-01-01

    The U.S. Environmental Protection Agency requested that the Navajo Nation conduct an assessment of aquifer sensitivity on Navajo Nation lands and an assessment of ground-water vulnerability to pesticide contamination on the Navajo Indian Irrigation Project. Navajo Nation lands include about 17,000 square miles in northeastern Arizona, northwestern New Mexico, and southeastern Utah. The Navajo Indian Irrigation Project in northwestern New Mexico is the largest area of agriculture on the Navajo Nation. The Navajo Indian Irrigation Project began operation in 1976; presently (2001) about 62,000 acres are available for irrigated agriculture. Numerous pesticides have been used on the Navajo Indian Irrigation Project during its operation. Aquifer sensitivity is defined by the U.S. Environmental Protection Agency as 'The relative ease with which a contaminant [pesticide] applied on or near a land surface can migrate to the aquifer of interest. Aquifer sensitivity is a function of the intrinsic characteristics of the geologic material in question, any underlying saturated materials, and the overlying unsaturated zone. Sensitivity is not dependent on agronomic practices or pesticide characteristics.' Ground-water vulnerability is defined by the U.S. Environmental Protection Agency as 'The relative ease with which a contaminant [pesticide] applied on or near a land surface can migrate to the aquifer of interest under a given set of agronomic management practices, pesticide characteristics, and aquifer sensitivity conditions.' The results of the aquifer sensitivity assessment on Navajo Nation and adjacent lands indicated relative sensitivity within the boundaries of the study area. About 22 percent of the study area was not an area of recharge to bedrock aquifers or an area of unconsolidated deposits and was thus assessed to have an insignificant potential for contamination. About 72 percent of the Navajo Nation study area was assessed to be in the categories of most potential

  2. Orientation and structure-building role of the water molecules bound at the contact surface of the dihydrofolate reductase-methotrexate complex

    NASA Astrophysics Data System (ADS)

    Nagy, P.

    1988-04-01

    Orientation of ten water molecules bound strongly at the contact surface of the dihydrofolate reductase-methotrexate enzyme-inhibitor complex was determined theoretically. To optimize the orientation of the water molecules, a recent method based on a simple electrostatic model was applied. The electrostatic complementarity in the binary complex was investigated using the lock-and-key model, considering the effect of the water molecules as well. The strongly bound water molecules improve the electrostatic fit in the pteridine region of methotrexate. Their role in the benzoic amide and γ-glutamate region is to decrease the internal energy by creating water bridges among remote polar sites making it possible to form H-bonds. Some modifications in the inhibitor structure were proposed for achieving greater inhibitor potency. The presumably enhanced effect is ascribed to the free energy gain in repelling the water molecules from the contact surface to the bulk of the solvent, and, in other cases, to internal energy decreases due to better electrostatic fit in the enzyme-inhibitor complex.

  3. Binding Energy of Molecules on Water Ice: Laboratory Measurements and Modeling

    NASA Astrophysics Data System (ADS)

    He, Jiao; Acharyya, Kinsuk; Vidali, Gianfranco

    2016-07-01

    We measured the binding energy of N2, CO, O2, CH4, and CO2 on non-porous (compact) amorphous solid water (np-ASW), of N2 and CO on porous ASW, and of NH3 on crystalline water ice. We were able to measure binding energies down to a fraction of 1% of a layer, thus making these measurements more appropriate for astrochemistry than the existing values. We found that CO2 forms clusters on the np-ASW surface even at very low coverages. The binding energies of N2, CO, O2, and CH4 decrease with coverage in the submonolayer regime. Their values at the low coverage limit are much higher than what is commonly used in gas-grain models. An empirical formula was used to describe the coverage dependence of the binding energies. We used the newly determined binding energy distributions in a simulation of gas-grain chemistry for cold cloud and hot-core models. We found that owing to the higher value of binding energy in the submonolayer regime, a fraction of all these ices remains for much longer and up to higher temperatures on the grain surface compared to the single value energies currently used in the astrochemical models.

  4. Water as probe molecule for midgap states in nanocrystalline strontium titanate by conventional and synchronous luminescence spectroscopy under ambient conditions

    NASA Astrophysics Data System (ADS)

    Taylor, Sean; Samokhvalov, Alexander

    2017-03-01

    Alkaline earth metal titanates are broad bandgap semiconductors with applications in electronic devices, as catalysts, photocatalysts, sorbents, and sensors. Strontium titanate SrTiO3 is of interest in electronic devices, sensors, in the photocatalytic hydrogen generation, as catalyst and sorbent. Both photocatalysis and operation of electronic devices rely upon the pathways of relaxation of excited charge in the semiconductor, including relaxation through the midgap states. We report characterization of nanocrystalline SrTiO3 at room temperature by "conventional" vs. synchronous luminescence spectroscopy and complementary methods. We determined energies of radiative transitions in the visible range through the two midgap states in the nanocrystalline SrTiO3. Further, adsorption and desorption of vapor of water as "probe molecule" for midgap states in the nanocrystalline SrTiO3 was studied, for the first time, by luminescence spectroscopy under ambient conditions. Emission of visible light from the nanocrystalline SrTiO3 is significantly increased upon desorption of water and decreased (quenched) upon adsorption of water vapor, due to interactions with the surface midgap states.

  5. Photo-electrochemical Oxidation of Organic C1 Molecules over WO3 Films in Aqueous Electrolyte: Competition Between Water Oxidation and C1 Oxidation.

    PubMed

    Reichert, Robert; Zambrzycki, Christian; Jusys, Zenonas; Behm, R Jürgen

    2015-11-01

    To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2 (+) and CO2 (+) ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2 , whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed.

  6. Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks

    PubMed Central

    Byun, Jeehye; Patel, Hasmukh A.; Thirion, Damien; Yavuz, Cafer T.

    2016-01-01

    Molecular architecture in nanoscale spaces can lead to selective chemical interactions and separation of species with similar sizes and functionality. Substrate specific sorbent chemistry is well known through highly crystalline ordered structures such as zeolites, metal organic frameworks and widely available nanoporous carbons. Size and charge-dependent separation of aqueous molecular contaminants, on the contrary, have not been adequately developed. Here we report a charge-specific size-dependent separation of water-soluble molecules through an ultra-microporous polymeric network that features fluorines as the predominant surface functional groups. Treatment of similarly sized organic molecules with and without charges shows that fluorine interacts with charges favourably. Control experiments using similarly constructed frameworks with or without fluorines verify the fluorine-cation interactions. Lack of a σ-hole for fluorine atoms is suggested to be responsible for this distinct property, and future applications of this discovery, such as desalination and mixed matrix membranes, may be expected to follow. PMID:27830697

  7. Incorporation of metabolically stable ketones into a small molecule probe to increase potency and water solubility.

    PubMed

    Larraufie, Marie-Helene; Yang, Wan Seok; Jiang, Elise; Thomas, Ajit G; Slusher, Barbara S; Stockwell, Brent R

    2015-11-01

    Introducing a reactive carbonyl to a scaffold that does not otherwise have an electrophilic functionality to create a reversible covalent inhibitor is a potentially useful strategy for enhancing compound potency. However, aldehydes are metabolically unstable, which precludes the use of this strategy for compounds to be tested in animal models or in human clinical studies. To overcome this limitation, we designed ketone-based functionalities capable of forming reversible covalent adducts, while displaying high metabolic stability, and imparting improved water solubility to their pendant scaffold. We tested this strategy on the ferroptosis inducer and experimental therapeutic erastin, and observed substantial increases in compound potency. In particular, a new carbonyl erastin analog, termed IKE, displayed improved potency, solubility and metabolic stability, thus representing an ideal candidate for future in vivo cancer therapeutic applications.

  8. Three-body breakup in dissociative electron attachment to the water molecule

    SciTech Connect

    Haxton, Daniel J.; Rescigno, Thomas N.; McCurdy, C. William

    2008-08-28

    We report the results of {\\em ab initio} calculations on dissociative electron attachment (DEA) to water that demonstrate the importance of including three-body breakup in the dissociation dynamics. While three-body breakup is ubiquitous in the analogous process of dissociative recombination, its importance in low-energy dissociative electron attachment to a polyatomic target has not previously been quantified. Our calculations, along with our earlier studies of DEA into two-body channels, indicate that three-body breakup is a major component of the observed O- cross section. The local complex potential model provides a generally accurate picture of the experimentallyobserved features in this system, reproducing some quantitatively, others qualitatively, and one not at all.

  9. Unified Effect of Hydrophobic Hydration on the Dynamics and the Structure of Water Molecules in Lower Alcohol Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Nakada, Masaru; Maruyama, Kenji; Yamamuro, Osamu; Kikuchi, Tatsuya; Misawa, Masakatsu

    2011-04-01

    After the analysis of the quasi-elastic neutron scattering (QENS) spectra of lower alcoholic aqueous solutions, we found that the parameter α, which is the number fraction of hydrophobic hydrating water molecules, has an important role in describing the dynamics and other properties of these solutions. The diffusion coefficient D was obtained from QENS spectra using the relaxing cage model, and D was found to have the same linear relation against α for ethyl alcohol, n-propyl alcohol, i-propyl alcohol, and t-butyl alcohol (with a small deviation) aqueous solutions. The excess molar volume and average hydration number of these solutions could also be expressed with common parameters, which are independent of the alcohol species.

  10. The signatures of stable isotopes δ 15N and δ 13C in anadromous and non-anadromous Coilia nasus living in the Yangtze River, and the adjacent sea waters

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Tang, Wenqiao; Dong, Wenxia

    2015-12-01

    Stable isotopes are increasingly used to investigate seasonal migrations of aquatic organisms. This study employed stable isotopes ( δ 13C and δ 15N) for Coilia nasus from the lower Yangtze River and the adjacent East China Sea to distinguish different ecotypic groups, ascertain trophic nutrition positions, and reflect environmental influences on C. nasus. δ 13C signatures of C. nasus sampled from Zhoushan (ZS), Chongming (CM), and Jingjiang (JJ) waters were significantly higher than those from the Poyang Lake (PYL) ( P < 0.05). By contrast, δ 15N signatures of C. nasus in ZS, CM, and JJ groups were significantly lower than those in PYL group ( P < 0.05). Basing on δ 13C and δ 15N signatures, we could distinguish anadromous (ZS, CM, and JJ) and non-anadromous (PYL) groups. The trophic level (TL) of anadromous C. nasus ranged from 2.90 to 3.04, whereas that of non-anadromous C. nasus was 4.38. C. nasus occupied the middle and top nutrition positions in the marine and Poyang Lake food webs, respectively. C. nasus in Poyang Lake were significantly more enriched in δ 15N but depleted in δ 13C, suggesting that anthropogenic nutrient inputs and terrigenous organic carbon are important to the Poyang Lake food web. This study is the first to apply δ 15N and δ 13C to population assignment studies of C. nasus in the Yangtze River and its affiliated waters. Analysis of stable isotopes ( δ 15N and δ 13C) is shown to be a useful tool for discriminating anadromous and non-anadromous C. nasus.

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

    NASA Astrophysics Data System (ADS)

    Chakraborty, Kaushik; Bandyopadhyay, Sanjoy

    2015-07-01

    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. Crystal Structure of Fatty Acid Amide Hydrolase Bound to the Carbamate Inhibitor URB597: Discovery of a Deacylating Water Molecule and Insight into Enzyme Inactivation

    SciTech Connect

    Mileni, Mauro; Kamtekar, Satwik; Wood, David C.; Benson, Timothy E.; Cravatt, Benjamin F.; Stevens, Raymond C.

    2010-08-12

    The endocannabinoid system regulates a wide range of physiological processes including pain, inflammation, and cognitive/emotional states. URB597 is one of the best characterized covalent inhibitors of the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH). Here, we report the structure of the FAAH-URB597 complex at 2.3 {angstrom} resolution. The structure provides insights into mechanistic details of enzyme inactivation and experimental evidence of a previously uncharacterized active site water molecule that likely is involved in substrate deacylation. This water molecule is part of an extensive hydrogen-bonding network and is coordinated indirectly to residues lining the cytosolic port of the enzyme. In order to corroborate our hypothesis concerning the role of this water molecule in FAAH's catalytic mechanism, we determined the structure of FAAH conjugated to a urea-based inhibitor, PF-3845, to a higher resolution (2.4 {angstrom}) than previously reported. The higher-resolution structure confirms the presence of the water molecule in a virtually identical location in the active site. Examination of the structures of serine hydrolases that are non-homologous to FAAH, such as elastase, trypsin, or chymotrypsin, shows a similarly positioned hydrolytic water molecule and suggests a functional convergence between the amidase signature enzymes and serine proteases.

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

    PubMed

    Chakraborty, Kaushik; Bandyopadhyay, Sanjoy

    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.

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

    SciTech Connect

    Chakraborty, Kaushik; Bandyopadhyay, Sanjoy

    2015-07-28

    Single-stranded DNA (ss-DNA) binding proteins specifically bind to the single-stranded regions of the DNA and protect it from premat