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Sample records for natural geochemical analogues

  1. Microbial Diversity in Engineered Haloalkaline Environments Shaped by Shared Geochemical Drivers Observed in Natural Analogues.

    PubMed

    Santini, Talitha C; Warren, Lesley A; Kendra, Kathryn E

    2015-08-01

    Microbial communities in engineered terrestrial haloalkaline environments have been poorly characterized relative to their natural counterparts and are geologically recent in formation, offering opportunities to explore microbial diversity and assembly in dynamic, geochemically comparable contexts. In this study, the microbial community structure and geochemical characteristics of three geographically dispersed bauxite residue environments along a remediation gradient were assessed and subsequently compared with other engineered and natural haloalkaline systems. In bauxite residues, bacterial communities were similar at the phylum level (dominated by Proteobacteria and Firmicutes) to those found in soda lakes, oil sands tailings, and nuclear wastes; however, they differed at lower taxonomic levels, with only 23% of operational taxonomic units (OTUs) shared with other haloalkaline environments. Although being less diverse than natural analogues, bauxite residue harbored substantial novel bacterial taxa, with 90% of OTUs nonmatchable to cultured representative sequences. Fungal communities were dominated by Ascomycota and Basidiomycota, consistent with previous studies of hypersaline environments, and also harbored substantial novel (73% of OTUs) taxa. In bauxite residues, community structure was clearly linked to geochemical and physical environmental parameters, with 84% of variation in bacterial and 73% of variation in fungal community structures explained by environmental parameters. The major driver of bacterial community structure (salinity) was consistent across natural and engineered environments; however, drivers differed for fungal community structure between natural (pH) and engineered (total alkalinity) environments. This study demonstrates that both engineered and natural terrestrial haloalkaline environments host substantial repositories of microbial diversity, which are strongly shaped by geochemical drivers. PMID:25979895

  2. Microbial Diversity in Engineered Haloalkaline Environments Shaped by Shared Geochemical Drivers Observed in Natural Analogues

    PubMed Central

    Warren, Lesley A.; Kendra, Kathryn E.

    2015-01-01

    Microbial communities in engineered terrestrial haloalkaline environments have been poorly characterized relative to their natural counterparts and are geologically recent in formation, offering opportunities to explore microbial diversity and assembly in dynamic, geochemically comparable contexts. In this study, the microbial community structure and geochemical characteristics of three geographically dispersed bauxite residue environments along a remediation gradient were assessed and subsequently compared with other engineered and natural haloalkaline systems. In bauxite residues, bacterial communities were similar at the phylum level (dominated by Proteobacteria and Firmicutes) to those found in soda lakes, oil sands tailings, and nuclear wastes; however, they differed at lower taxonomic levels, with only 23% of operational taxonomic units (OTUs) shared with other haloalkaline environments. Although being less diverse than natural analogues, bauxite residue harbored substantial novel bacterial taxa, with 90% of OTUs nonmatchable to cultured representative sequences. Fungal communities were dominated by Ascomycota and Basidiomycota, consistent with previous studies of hypersaline environments, and also harbored substantial novel (73% of OTUs) taxa. In bauxite residues, community structure was clearly linked to geochemical and physical environmental parameters, with 84% of variation in bacterial and 73% of variation in fungal community structures explained by environmental parameters. The major driver of bacterial community structure (salinity) was consistent across natural and engineered environments; however, drivers differed for fungal community structure between natural (pH) and engineered (total alkalinity) environments. This study demonstrates that both engineered and natural terrestrial haloalkaline environments host substantial repositories of microbial diversity, which are strongly shaped by geochemical drivers. PMID:25979895

  3. Natural geochemical analogues of the near field of high-level nuclear waste repositories

    SciTech Connect

    Apps, J.A.

    1995-09-01

    United States practice has been to design high-level nuclear waste (HLW) geological repositories with waste densities sufficiently high that repository temperatures surrounding the waste will exceed 100{degrees}C and could reach 250{degrees}C. Basalt and devitrified vitroclastic tuff are among the host rocks considered for waste emplacement. Near-field repository thermal behavior and chemical alteration in such rocks is expected to be similar to that observed in many geothermal systems. Therefore, the predictive modeling required for performance assessment studies of the near field could be validated and calibrated using geothermal systems as natural analogues. Examples are given which demonstrate the need for refinement of the thermodynamic databases used in geochemical modeling of near-field natural analogues and the extent to which present models can predict conditions in geothermal fields.

  4. Geochemical Processes During Geological Carbon Storage: Lessons from Natural Analogues and Field Experiments (Invited)

    NASA Astrophysics Data System (ADS)

    Bickle, M. J.; Kampman, N.; Wigley, M.; Dubacq, B.

    2013-12-01

    that fluid-mineral reactions are initially fast, are important in buffering fluid compositions and may cause important beneficial changes to formation and caprock permeabilities. However much more needs to be learnt. Many of the inferences on mineral dissolution and precipitation reactions are derived from modal decomposition calculations based on changes in sampled fluid chemistry and these suffer ambiguities arising from the limited number of soluble cations present in stoichiometric proportions in minerals and from the uncertainties in mineral compositions. The reservoirs and caprocks in natural analogues contain an inadequately sampled and exploited record of the fluid-mineral reactions but deciphering this requires careful petrographic, mineralogical and geochemical work to distinguish the response to CO2-charged fluids from earlier diagenetic episodes.

  5. Natural Analogue Synthesis Report

    SciTech Connect

    A. M. Simmons

    2002-05-01

    The purpose of this report is to present analogue studies and literature reviews designed to provide qualitative and quantitative information to test and provide added confidence in process models abstracted for performance assessment (PA) and model predictions pertinent to PA. This report provides updates to studies presented in the ''Yucca Mountain Site Description'' (CRWMS M and O 2000 [151945], Section 13) and new examples gleaned from the literature, along with results of quantitative studies conducted specifically for the Yucca Mountain Site Characterization Project (YMP). The intent of the natural analogue studies was to collect corroborative evidence from analogues to demonstrate additional understanding of processes expected to occur during postclosure at a potential Yucca Mountain repository. The report focuses on key processes by providing observations and analyses of natural and anthropogenic (human-induced) systems to improve understanding and confidence in the operation of these processes under conditions similar to those that could occur in a nuclear waste repository. The process models include those that represent both engineered and natural barrier processes. A second purpose of this report is to document the various applications of natural analogues to geologic repository programs, focusing primarily on the way analogues have been used by the YMP. This report is limited to providing support for PA in a confirmatory manner and to providing corroborative inputs for process modeling activities. Section 1.7 discusses additional limitations of this report. Key topics for this report are analogues to emplacement drift degradation, waste form degradation, waste package degradation, degradation of other materials proposed for the engineered barrier, seepage into drifts, radionuclide flow and transport in the unsaturated zone (UZ), analogues to coupled thermal-hydrologic-mechanical-chemical processes, saturated zone (SZ) transport, impact of radionuclide

  6. Distribution and geochemical characterization of coalbed gases at excavation fields at natural analogue site area Velenje Basin, Slovenia

    NASA Astrophysics Data System (ADS)

    Kanduč, Tjaša; Žigon, Stojan; Grassa, Fausto; Sedlar, Jerneja; Zadnik, Ivo; Zavšek, Simon

    2016-04-01

    Unconventional gas resources, including coal bed methane and shale gas, are a growing part of the global energy mix, which has changed the economic and strategic picture for gas consuming and producing countries, including the USA, China and Australia that, together are responsible for around half the currently recoverable unconventional gas resources. However, CBM production was often hindered by low permeability and mineralization in cleats and fractures, necessitating the development of cost effective horizontal drilling and completion techniques. Geochemical and isotopic monitoring of coalbed gases at excavation fields in Velenje Basin started in year 2000, with the aim to obtain better insights into the origin of coalbed gases. Results from active excavation fields in the mining areas Pesje and Preloge in the year period 2014-2015 are presented in this study. Composition and isotopic composition of coalbed gases were determined with mass - spectrometric methods. The chemical (methane, carbon dioxide, nitrogen) and isotopic composition of carbon in methane and carbon dioxide in the Velenje Basin vary and depend on the composition of the source of coalbed gas before excavation, advancement of the working face, depth of the longwall face, pre-mining activity and newly mined activity. The basic gas components determined in excavation fields are carbon dioxide and methane. Knowledge of the stable isotope geochemistry of coal bed and shale gas and the related production water is essential to determine not only gas origins but also the dominant methanogenic pathway in the case of microbial gas. Concentrations of methane at active excavation fields are changing from 1.8 to 63.9 %, concentrations of carbon dioxide are changing from 36.1 to 98.2% and CDMI (Carbon Dioxide Methane Index) index from 0.2 to 100 %. Isotopic composition of carbon dioxide is changing from -11.0 to -1.9‰ , isotopic composition of methane from -71.8 to -43.3‰ , isotopic composition of

  7. The Valles natural analogue project

    SciTech Connect

    Stockman, H.; Krumhansl, J.; Ho, C.; McConnell, V.

    1994-12-01

    The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a highlevel waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, X-ray diffraction; and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and {sup 39}Ar/{sup 4O} isotopic composition. Overall,the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 meters of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks.

  8. Natural analogue studies: present status and performance assessment implications

    NASA Astrophysics Data System (ADS)

    Smellie, John A. T.; Karlsson, Fred; Alexander, W. Russell

    1997-04-01

    Studies of natural geological and archaeological systems as analogues to long-term processes, which are predicted to occur within a radioactive waste repository environment, have become increasingly popular over the last 10 years or so, to the extent that such studies form an integral part of many national programmes for radioactive waste disposal. There is now a common consensus that the natural analogue approach is a very useful scientific methodology to: (a) identify and understand processes and mechanisms analogous to those which could occur in the vicinity of a repository over realistic timescales, (b) derive input data which have been successfully used to test some of the laboratory-based models which form the basis of long-term repository performance assessment, and (c) to produce data which can be input directly to performance assessment models. Increasingly, analogues are playing an important role in public awareness, enabling the layman to understand better the concept of radioactive disposal and demonstrating the reliability of the disposal system over long periods of geological time. The complexity of geological systems means that it is very often difficult and sometimes impossible to quantify precisely the physico-chemical boundary conditions necessary to model a particular geochemical process or mechanism. Consequently, the availability of quantitative analogue data is limited when repository performance assessments are considered. However, this in no way detracts from their value in building confidence by demonstrating that important processes do exist and by showing qualitatively that they behave in a way predicted by models based on laboratory-derived data. The transfer of natural analogue data from the complexity of field studies to simplistic models which, by necessity, are used in performance assessments, is an area of activity which is presently being addressed. Field analogue studies are now being planned to interface with laboratory

  9. Natural analogues of nuclear waste glass corrosion.

    SciTech Connect

    Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

    1999-01-06

    This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses.

  10. Long-term predictions using natural analogues

    SciTech Connect

    Ewing, R.C.

    1995-09-01

    One of the unique and scientifically most challenging aspects of nuclear waste isolation is the extrapolation of short-term laboratory data (hours to years) to the long time periods (10{sup 3}-10{sup 5} years) required by regulatory agencies for performance assessment. The direct validation of these extrapolations is not possible, but methods must be developed to demonstrate compliance with government regulations and to satisfy the lay public that there is a demonstrable and reasonable basis for accepting the long-term extrapolations. Natural systems (e.g., {open_quotes}natural analogues{close_quotes}) provide perhaps the only means of partial {open_quotes}validation,{close_quotes} as well as data that may be used directly in the models that are used in the extrapolation. Natural systems provide data on very large spatial (nm to km) and temporal (10{sup 3}-10{sup 8} years) scales and in highly complex terranes in which unknown synergisms may affect radionuclide migration. This paper reviews the application (and most importantly, the limitations) of data from natural analogue systems to the {open_quotes}validation{close_quotes} of performance assessments.

  11. Natural analogue studies of the role of colloids, natural organics and microorganisms on radionuclide transport

    SciTech Connect

    McCarthy, J.F.

    1994-10-01

    Colloids may be important as a geochemical transport mechanism for radionuclides at geological repositories if they are (1) present in the groundwater, (2) stable with respect to both colloidal and chemical stabilities, (3) capable of adsorbing radionuclides, especially if the sorption is irreversible, and (4) mobile in the subsurface. The available evidence from natural analogue and other field studies relevant to these issues is reviewed, as is the potential role of mobile microorganisms ({open_quotes}biocolloids{close_quotes}) on radionuclide migration. Studies have demonstrated that colloids are ubiquitous in groundwater, although colloid concentrations in deep, geochemically stable systems may be too low to affect radionuclide transport. However, even low colloid populations cannot be dismissed as a potential concern because colloids appear to be stable, and many radionuclides that adsorb to colloids are not readily desorbed over long periods. Field studies offer somewhat equivocal evidence concerning colloid mobility and cannot prove or disprove the significance of colloid transport in the far-field environment. Additional research is needed at new sites to properly represent a repository far-field. Performance assessment would benefit from natural analogue studies to examine colloid behavior at sites encompassing a suite of probable groundwater chemistries and that mimic the types of formations selected for radioactive waste repositories.

  12. U.S. Nuclear Regulatory Commission natural analogue research program

    SciTech Connect

    Kovach, L.A.; Ott, W.R.

    1995-09-01

    This article describes the natural analogue research program of the U.S. Nuclear Regulatory Commission (US NRC). It contains information on the regulatory context and organizational structure of the high-level radioactive waste research program plan. It also includes information on the conditions and processes constraining selection of natural analogues, describes initiatives of the US NRC, and describes the role of analogues in the licensing process.

  13. Variation of Geochemical Signatures and Correlation of Biomarkers in Icelandic Mars Analogue Environments

    NASA Astrophysics Data System (ADS)

    Gentry, D.; Amador, E. S.; Cable, M. L.; Cantrell, T.; Chaudry, N.; Cullen, T.; Duca, Z. A.; Jacobsen, M. B.; McCaig, H. C.; Murukesan, G.; Rennie, V.; Schwieterman, E. W.; Stevens, A. H.; Tan, G.; Yin, C.; Stockton, A.; Cullen, D.; Geppert, W.

    2015-12-01

    Exploration missions to Mars rely on rovers to perform deep analyses over small sampling areas; however, landing site selection is done using large-scale but low-resolution remote sensing data. Using Earth analogue environments to estimate the small-scale spatial and temporal distributions of key geochemical signatures and (for habitability studies) biomarkers helps ensure that the chosen sampling strategies meet mission science goals. We conducted two rounds of analogue expeditions to recent Icelandic lava fields. In July 2013, we tested correlation between three common biomarker assays: cell quantification via fluorescence microscopy, ATP quantification via bioluminescence, and quantitative PCR with universal primer sets. Sample sites were nested at four spatial scales (1 m, 10 m, 100 m, and > 1 km) and homogeneous at 'remote imaging' resolution (overall temperature, apparent moisture content, and regolith grain size). All spatial scales were highly diverse in ATP, bacterial 16S, and archaeal 16S DNA content; nearly half of sites were statistically different in ATP content at α = 0.05. Cell counts showed significant variation at the 10 m and 100 m scale; at the > 1 km scale, the mean counts were not distinguishable, but the median counts were, indicating differences in underlying distribution. Fungal 18S DNA content similarly varied at 1 m, 10 m, and 100 m scales only. Cell counts were not correlated with ATP or DNA content at any scale. ATP concentration and DNA content for all three primer sets were positively correlated. Bacterial DNA content was positively correlated with archaeal and fungal DNA content, though archaeal correlation was weak. Fungal and archaeal correlation was borderline. In July 2015, we repeated the sampling strategy, with the addition of a smaller-scale sampling grid of 10 cm and a third > 1 km location. This expedition also measured reflectance of the tephra cover and preserved mineral samples for future Raman spectroscopy in order to

  14. Río Tinto: A Geochemical and Mineralogical Terrestrial Analogue of Mars

    PubMed Central

    Amils, Ricardo; Fernández-Remolar, David

    2014-01-01

    The geomicrobiological characterization of the water column and sediments of Río Tinto (Huelva, Southwestern Spain) have proven the importance of the iron and the sulfur cycles, not only in generating the extreme conditions of the habitat (low pH, high concentration of toxic heavy metals), but also in maintaining the high level of microbial diversity detected in the basin. It has been proven that the extreme acidic conditions of Río Tinto basin are not the product of 5000 years of mining activity in the area, but the consequence of an active underground bioreactor that obtains its energy from the massive sulfidic minerals existing in the Iberian Pyrite Belt. Two drilling projects, MARTE (Mars Astrobiology Research and Technology Experiment) (2003–2006) and IPBSL (Iberian Pyrite Belt Subsurface Life Detection) (2011–2015), were developed and carried out to provide evidence of subsurface microbial activity and the potential resources that support these activities. The reduced substrates and the oxidants that drive the system appear to come from the rock matrix. These resources need only groundwater to launch diverse microbial metabolisms. The similarities between the vast sulfate and iron oxide deposits on Mars and the main sulfide bioleaching products found in the Tinto basin have given Río Tinto the status of a geochemical and mineralogical Mars terrestrial analogue. PMID:25370383

  15. Río tinto: a geochemical and mineralogical terrestrial analogue of Mars.

    PubMed

    Amils, Ricardo; Fernández-Remolar, David; The Ipbsl Team

    2014-01-01

    The geomicrobiological characterization of the water column and sediments of Río Tinto (Huelva, Southwestern Spain) have proven the importance of the iron and the sulfur cycles, not only in generating the extreme conditions of the habitat (low pH, high concentration of toxic heavy metals), but also in maintaining the high level of microbial diversity detected in the basin. It has been proven that the extreme acidic conditions of Río Tinto basin are not the product of 5000 years of mining activity in the area, but the consequence of an active underground bioreactor that obtains its energy from the massive sulfidic minerals existing in the Iberian Pyrite Belt. Two drilling projects, MARTE (Mars Astrobiology Research and Technology Experiment) (2003-2006) and IPBSL (Iberian Pyrite Belt Subsurface Life Detection) (2011-2015), were developed and carried out to provide evidence of subsurface microbial activity and the potential resources that support these activities. The reduced substrates and the oxidants that drive the system appear to come from the rock matrix. These resources need only groundwater to launch diverse microbial metabolisms. The similarities between the vast sulfate and iron oxide deposits on Mars and the main sulfide bioleaching products found in the Tinto basin have given Río Tinto the status of a geochemical and mineralogical Mars terrestrial analogue. PMID:25370383

  16. Río tinto: a geochemical and mineralogical terrestrial analogue of Mars.

    PubMed

    Amils, Ricardo; Fernández-Remolar, David; The Ipbsl Team

    2014-09-15

    The geomicrobiological characterization of the water column and sediments of Río Tinto (Huelva, Southwestern Spain) have proven the importance of the iron and the sulfur cycles, not only in generating the extreme conditions of the habitat (low pH, high concentration of toxic heavy metals), but also in maintaining the high level of microbial diversity detected in the basin. It has been proven that the extreme acidic conditions of Río Tinto basin are not the product of 5000 years of mining activity in the area, but the consequence of an active underground bioreactor that obtains its energy from the massive sulfidic minerals existing in the Iberian Pyrite Belt. Two drilling projects, MARTE (Mars Astrobiology Research and Technology Experiment) (2003-2006) and IPBSL (Iberian Pyrite Belt Subsurface Life Detection) (2011-2015), were developed and carried out to provide evidence of subsurface microbial activity and the potential resources that support these activities. The reduced substrates and the oxidants that drive the system appear to come from the rock matrix. These resources need only groundwater to launch diverse microbial metabolisms. The similarities between the vast sulfate and iron oxide deposits on Mars and the main sulfide bioleaching products found in the Tinto basin have given Río Tinto the status of a geochemical and mineralogical Mars terrestrial analogue.

  17. Río Tinto: A Geochemical and Mineralogical Terrestrial Analogue of Mars

    NASA Astrophysics Data System (ADS)

    Amils, Ricardo; Fernández-Remolar, David

    2014-09-01

    The geomicrobiological characterization of the water column and sediments of Río Tinto (Huelva, Southwestern Spain) have proven the importance of the iron and the sulfur cycles, not only in generating the extreme conditions of the habitat (low pH, high concentration of toxic heavy metals), but also in maintaining the high level of microbial diversity detected in the basin. It has been proven that the extreme acidic conditions of Río Tinto basin are not the product of 5000 years of mining activity in the area, but the consequence of an active underground bioreactor that obtains its energy from the massive sulfidic minerals existing in the Iberian Pyrite Belt. Two drilling projects, MARTE (Mars Astrobiology Research and Technology Experiment) (2003-2006) and IPBSL (Iberian Pyrite Belt Subsurface Life Detection) (2011-2015), were developed and carried out to provide evidence of subsurface microbial activity and the potential resources that support these activities. The reduced substrates and the oxidants that drive the system appear to come from the rock matrix. These resources need only groundwater to launch diverse microbial metabolisms. The similarities between the vast sulfate and iron oxide deposits on Mars and the main sulfide bioleaching products found in the Tinto basin have given Río Tinto the status of a geochemical and mineralogical Mars terrestrial analogue.

  18. Naturally occurring crystalline phases: analogues for radioactive waste forms

    SciTech Connect

    Haaker, R.F.; Ewing, R.C.

    1981-01-01

    Naturally occurring mineral analogues to crystalline phases that are constituents of crystalline radioactive waste forms provide a basis for comparison by which the long-term stability of these phases may be estimated. The crystal structures and the crystal chemistry of the following natural analogues are presented: baddeleyite, hematite, nepheline; pollucite, scheelite;sodalite, spinel, apatite, monazite, uraninite, hollandite-priderite, perovskite, and zirconolite. For each phase in geochemistry, occurrence, alteration and radiation effects are described. A selected bibliography for each phase is included.

  19. Iberian Pyrite Belt Subsurface Life (IPBSL), a drilling project in a geochemical Mars terrestrial analogue

    NASA Astrophysics Data System (ADS)

    Amils, R.; Fernández-Remolar, D. C.; Parro, V.; Manfredi, J. A.; Timmis, K.; Oggerin, M.; Sánchez-Román, M.; López, F. J.; Fernández, J. P.; Omoregie, E.; Gómez-Ortiz, D.; Briones, C.; Gómez, F.; García, M.; Rodríguez, N.; Sanz, J. L.

    2012-09-01

    Iberian Pyrite Belt Subsurface Life (IPBSL) is a drilling project specifically designed to characterize the subsurface ecosystems operating in the Iberian Pyrite Belt (IPB), in the area of Peña de Hierro, and responsible of the extreme acidic conditions existing in the Rio Tinto basin [1]. Rio Tinto is considered a good geochemical terrestrial analogue of Mars [2, 3]. A dedicated geophysical characterization of the area selected two drilling sites (4) due to the possible existence of water with high ionic content (low resistivity). Two wells have been drilled in the selected area, BH11 and BH10, of depths of 340 and 620 meters respectively, with recovery of cores and generation of samples in anaerobic and sterile conditions. Preliminary results showed an important alteration of mineral structures associated with the presence of water, with production of expected products from the bacterial oxidation of pyrite (sulfates and ferric iron). Ion chromatography of water soluble compounds from uncontaminated samples showed the existence of putative electron donors (ferrous iron, nitrite in addition of the metal sulfides), electron acceptors (sulfate, nitrate, ferric iron) as well as variable concentration of metabolic organic acids (mainly acetate, formate, propionate and oxalate), which are strong signals of the presence of active subsurface ecosystem associated to the high sulfidic mineral content of the IPB. The system is driven by oxidants that appear to be provided by the rock matrix, only groundwater is needed to launch microbial metabolism. The geological, geomicrobiological and molecular biology analysis which are under way, should allow the characterization of this ecosystem of paramount interest in the design of an astrobiological underground Mars exploration mission in the near future.

  20. Facile Synthesis of Natural Alkoxynaphthalene Analogues from Plant Alkoxybenzenes.

    PubMed

    Tsyganov, Dmitry V; Krayushkin, Mikhail M; Konyushkin, Leonid D; Strelenko, Yuri A; Semenova, Marina N; Semenov, Victor V

    2016-04-22

    Analogues of the bioactive natural alkoxynaphthalene pycnanthulignene D were synthesized by an efficient method. The starting plant allylalkoxybenzenes (1) are easily available from the plant essential oils of sassafras, dill, and parsley. The target 1-arylalkoxynaphthalenes (5) exhibited antiproliferative activity in a phenotypic sea urchin embryo assay. PMID:26910798

  1. Facile Synthesis of Natural Alkoxynaphthalene Analogues from Plant Alkoxybenzenes.

    PubMed

    Tsyganov, Dmitry V; Krayushkin, Mikhail M; Konyushkin, Leonid D; Strelenko, Yuri A; Semenova, Marina N; Semenov, Victor V

    2016-04-22

    Analogues of the bioactive natural alkoxynaphthalene pycnanthulignene D were synthesized by an efficient method. The starting plant allylalkoxybenzenes (1) are easily available from the plant essential oils of sassafras, dill, and parsley. The target 1-arylalkoxynaphthalenes (5) exhibited antiproliferative activity in a phenotypic sea urchin embryo assay.

  2. Magnesite formation in playas: A natural analogue for carbon sequestration

    NASA Astrophysics Data System (ADS)

    Power, Ian; Harrison, Anna; Wilson, Siobhan; Dipple, Gregory; Fallon, Stewart

    2015-04-01

    Non-marine carbonate deposits are of renewed interest as natural analogues for carbon sequestration and storage. Specifically, the sequestration of anthropogenic carbon dioxide (CO2)in Mg-carbonate minerals is being actively investigated as a strategy for reducing greenhouse gas emissions1. In northern British Columbia, hydromagnesite-magnesite playas (hectare-scale) have formed since the last deglaciation, suggesting that these minerals possess a level of stability required for long-term carbon storage2. Quantitative mineralogical and hydrogeochemical data, as well as microscopy and field observations, were used to formulate a comprehensive facies model that describes the depositional environments for the formation of these playas. Over several millennia, there have been transitions from deposition of siliciclastic to subaqueous Ca-Mg-carbonate to subaerial Mg-carbonate sediments3,4. Consequently, a complex assemblage of carbonate minerals is present within the playas including magnesite [MgCO3], the most stable Mg-carbonate for storing CO2. Magnesite precipitation at near-surface temperatures is kinetically inhibited due to the strong hydration of Mg2+ ions in solution5. Thus, understanding the rates of, and controls on, magnesite formation at low temperatures remains a challenge. Magnesite abundances at the surface (1 to 41 wt.%) and at depth (1 to 86 wt.%) within the playas are highly variable4. There is a propensity for hydrated Mg-carbonate minerals to undergo transformation to less hydrated, more stable forms (lansfordite > nesquehonite > dypingite > hydromagnesite)5; however, stable, radiogenic, and clumped isotope6 data as well as electron microscopy demonstrate that magnesite formation is likely dominated by direct precipitation from aqueous solution in the shallow subsurface (~3-10 ° C). An observed variation in magnesite crystal morphology with depth is attributed to different crystal growth mechanisms induced by changes in magnesite saturation state

  3. Design and synthesis of analogues of natural products.

    PubMed

    Maier, Martin E

    2015-05-21

    In this article strategies for the design and synthesis of natural product analogues are summarized and illustrated with some selected examples. Proven strategies include diverted total synthesis (DTS), function-oriented synthesis (FOS), biology-oriented synthesis (BIOS), complexity to diversity (CtD), hybrid molecules, and biosynthesis inspired synthesis. The latter includes mutasynthesis, the synthesis of natural products encoded by silent genes, and propionate scanning. Most of the examples from our group fall in the quite general concept of DTS. Thus, in case an efficient strategy to a natural product is at hand, modifications are possible at almost any stage of a synthesis. However, even for compounds of moderate complexity, organic synthesis remains a bottle neck. Unless some method for predicting the biological activity of a designed molecule becomes available, the design and synthesis of natural product analogues will remain what it is now, namely it will largely rely on trial and error. PMID:25829247

  4. Non-natural acetogenin analogues as potent Trypanosoma brucei inhibitors.

    PubMed

    Florence, Gordon J; Fraser, Andrew L; Gould, Eoin R; King, Elizabeth F B; Menzies, Stefanie K; Morris, Joanne C; Tulloch, Lindsay B; Smith, Terry K

    2014-11-01

    Neglected tropical diseases remain a serious global health concern. Here, a series of novel bis-tetrahydropyran 1,4-triazole analogues based on the framework of chamuvarinin, a polyketide natural product isolated from the annonaceae plant species are detailed. The analogues synthesized display low micromolar trypanocidal activities towards both bloodstream and insect forms of Trypanosoma brucei, the causative agent of African sleeping sickness, also known as Human African Trypanosomiasis (HAT). A divergent synthetic strategy was adopted for the synthesis of the key tetrahydropyran intermediates to enable rapid access to diastereochemical variation either side of the 1,4-triazole core. The resulting diastereomeric analogues displayed varying degrees of trypanocidal activity and selectivity in structure-activity relationship studies. Together, the biological potency and calculated lipophilicity values indicate that while there is room for improvement, these derivatives may represent a promising novel class of anti-HAT agents.

  5. Using fuzzy sets for data interpretation in natural analogue studies

    SciTech Connect

    De Lemos, F.L.; Sullivan, T.; Hellmuth, K.H.

    2008-07-01

    Natural analogue studies can play a key role in deep geological radioactive disposal systems safety assessment. These studies can help develop a better understanding of complex natural processes and, therefore, provide valuable means of confidence building in the safety assessment. In evaluation of natural analogues, there are, however, several sources of uncertainties that stem from factors such as complexity; lack of data; and ignorance. Often, analysts have to simplify the mathematical models in order to cope with the various sources of complexity and this ads uncertainty to the model results. The uncertainties reflected in model predictions must be addressed to understand their impact on safety assessment and therefore, the utility of natural analogues. Fuzzy sets can be used to represent the information regarding the natural processes and their mutual connections. With this methodology we are able to quantify and propagate the epistemic uncertainties in both processes and, thereby, assign degrees of truth to the similarities between them. An example calculation with literature data is provided. In conclusion: Fuzzy sets are an effective way of quantifying semi-quantitative information such as natural analogues data. Epistemic uncertainty that stems from complexity and lack of knowledge regarding natural processes are represented by the degrees of membership. It also facilitates the propagation of this uncertainty throughout the performance assessment by the extension principle. This principle allows calculation with fuzzy numbers, where fuzzy input results in fuzzy output. This may be one of the main applications of fuzzy sets theory to radioactive waste disposal facility performance assessment. Through the translation of natural data into fuzzy numbers, the effect of parameters in important processes in one site can be quantified and compared to processes in other sites with different conditions. The approach presented in this paper can be extended to

  6. THE PENA BLANCA NATURAL ANALOGUE PERFORMANCE ASSESSMENT MODEL

    SciTech Connect

    G. Saulnier and W. Statham

    2006-04-16

    The Nopal I uranium mine in the Sierra Pena Blanca, Chihuahua, Mexico serves as a natural analogue to the Yucca Mountain repository. The Pena Blanca Natural Analogue Performance Assessment Model simulates the mobilization and transport of radionuclides that are released from the mine and transported to the saturated zone. The Pena Blanca Natural Analogue Performance Assessment Model uses probabilistic simulations of hydrogeologic processes that are analogous to the processes that occur at the Yucca Mountain site. The Nopal I uranium deposit lies in fractured, welded, and altered rhyolitic ash-flow tuffs that overlie carbonate rocks, a setting analogous to the geologic formations at the Yucca Mountain site. The Nopal I mine site has the following analogous characteristics as compared to the Yucca Mountain repository site: (1) Analogous source--UO{sub 2} uranium ore deposit = spent nuclear fuel in the repository; (2) Analogous geology--(i.e. fractured, welded, and altered rhyolitic ash-flow tuffs); (3) Analogous climate--Semiarid to arid; (4) Analogous setting--Volcanic tuffs overlie carbonate rocks; and (5) Analogous geochemistry--Oxidizing conditions Analogous hydrogeology: The ore deposit lies in the unsaturated zone above the water table.

  7. THE PENA BLANCA NATURAL ANALOGUE PERFORMANCE ASSESSMENT MODEL

    SciTech Connect

    G.J. Saulnier Jr; W. Statham

    2006-03-10

    The Nopal I uranium mine in the Sierra Pena Blanca, Chihuahua, Mexico serves as a natural analogue to the Yucca Mountain repository. The Pena Blanca Natural Analogue Performance Assessment Model simulates the mobilization and transport of radionuclides that are released from the mine and transported to the saturated zone. the Pena Blanca Natural Analogue Model uses probabilistic simulations of hydrogeologic processes that are analogous to the processes that occur at the Yucca Mountain site. The Nopal I uranium deposit lies in fractured, welded, and altered rhyolitic ash flow tuffs that overlie carbonate rocks, a setting analogous to the geologic formations at the Yucca Mountain site. The Nopal I mine site has the following characteristics as compared to the Yucca Mountain repository site. (1) Analogous source: UO{sub 2} uranium ore deposit = spent nuclear fuel in the repository; (2) Analogous geologic setting: fractured, welded, and altered rhyolitic ash flow tuffs overlying carbonate rocks; (3) Analogous climate: Semiarid to arid; (4) Analogous geochemistry: Oxidizing conditions; and (5) Analogous hydrogeology: The ore deposit lies in the unsaturated zone above the water table. The Nopal I deposit is approximately 8 {+-} 0.5 million years old and has been exposed to oxidizing conditions during the last 3.2 to 3.4 million years. The Pena Blanca Natural Analogue Model considers that the uranium oxide and uranium silicates in the ore deposit were originally analogous to uranium-oxide spent nuclear fuel. The Pena Blanca site has been characterized using field and laboratory investigations of its fault and fracture distribution, mineralogy, fracture fillings, seepage into the mine adits, regional hydrology, and mineralization that shows the extent of radionuclide migration. Three boreholes were drilled at the Nopal I mine site in 2003 and these boreholes have provided samples for lithologic characterization, water-level measurements, and water samples for laboratory

  8. Interglacial analogues of the Holocene and its natural near future

    NASA Astrophysics Data System (ADS)

    Yin, Qiuzhen; Berger, André

    2015-07-01

    In an attempt to find potential interglacial analogues of our present interglacial and its natural future, five interglacials (MIS-1, 5, 9, 11 and 19) are studied in terms of their astronomical characteristics, greenhouse gases concentration and climate simulated using both snapshot and transient experiments. Transient simulations covering a full range of obliquity, precession and eccentricity allow to develop an OPE index to estimate the climate sensitivity to astronomical forcing. They also show that obliquity and precession have different weight on the annual mean temperature and precipitation of different latitudinal zones, leading to varying phasing of these climate variables between different latitudes. However, the variations in boreal summer temperature of different latitudes (except the Southern Ocean) are in phase and are dominated by precession. All the interglacials are shown to be warmer than the natural climate of the present day and of the next centuries during boreal summer and for the annual mean temperature with varying duration and intensity. Such warming is mainly caused by changes in insolation, unlike the present global warming which mainly results from anthropogenic CO2 increase. The exceptionally long duration of MIS-11 is confirmed by our simulations, and it is demonstrated to be related to the long-lasting low eccentricity and high CO2 concentration and to the anti-phase relationship between obliquity maximum and precession minimum during MIS-11. As far as the variations of annual and seasonal temperatures are concerned, both snapshot and transient simulations show that MIS-19 is the best analogue of the present interglacial. MIS-11 is also a decent analogue when the impact of insolation alone is considered, but it is warmer than MIS-1 when the impact of CO2 is additionally included. Due to the large amplitude in the variations of insolation, MIS-5 and MIS-9 can hardly be considered as an analogue of the natural present-day climate and of

  9. Natural analogue studies as supplements to biomineralization research

    SciTech Connect

    McNeil, M.B.

    1995-09-01

    Chemical reactions can alter the chemistry and crystal structure of solid objects over archeological or geological times, while preserving external physical shapes. The reactions resulting in these structures offer natural analogues to laboratory experiments in biomineralization and to biologically influenced alteration of nuclear waste packages, and thus, they offer the only available way of validating models that purport waste package behavior over archaeological or geological times. Potential uses of such analogues in the construction and validation of hypothetical mechanisms of microbiological corrosion and biomineralization are reviewed. Evidence from such analogues suggests that biofilms can control materials alteration in ways usually overlooked. The newly hypothesized mechanisms involve control by biofilms of the cation flow near the solid surface and offer plausible mechanisms for the formation of mixed-cation minerals under conditions that would lead to dealloying in abiotic experiments; they also account for the formation of unusual minerals [such as posnjakite, Cu{sub 4}SO{sub 4}(OH){sub 6{center_dot}}H{sub 2}O] and mineral morphologies unusual in corrosion [malachite, Cu{sub 2}CO{sub 3}(OH){sub 2}, rarely forms botryoidally under corrosion conditions and its occasional presence on archaeological objects that appear to have undergone microbiological corrosion may be related to biofilm phenomena].

  10. Pena Blanca Natural Analogue Project: Summary of activities

    SciTech Connect

    Levy, S.; Goldstein, S.; Dobson, P.F.; Goodell, P.; Ku, T.-L.; Abdel-Fattah, A.; Saulnier, G.; Fayek, M.; de la Garza, R.

    2011-02-01

    The inactive Nopal I uranium mine in silicic tuff north of Chihuahua City, Chihuahua, Mexico, was studied as a natural analogue for an underground nuclear-waste repository in the unsaturated zone. Site stratigraphy was confirmed from new drill cores. Data from site studies include chemical and isotopic compositions of saturated- and unsaturated-zone waters. A partial geochronology of uranium enrichment and mineralization was established. Evidence pertinent to uranium-series transport in the soil zone and changing redox conditions was collected. The investigations contributed to preliminary, scoping-level performance assessment modeling.

  11. Pena blanca natural analogue project: summary of activities

    SciTech Connect

    Levy, Schon S; Goldstein, Steven J; Abdel - Fattah, Amr I

    2010-12-08

    The inactive Nopal I uranium mine in silicic tuff north of Chihuahua City, Chihuahua, Mexico, was studied as a natural analogue for an underground nuclear-waste repository in the unsaturated zone. Site stratigraphy was confirmed from new drill core. Datafrom site studies include chemical and isotopic compositions of saturated- and unsaturated-zone waters. A partial geochronology of uranium enrichment and mineralization was established. Evidence pertinent to uranium-series transport in the soil zone and changing redox conditions was collected. The investigations contributed to preliminary, scoping-level performance assessment modeling.

  12. Microbially mediated redox processes in natural analogues for radioactive waste

    NASA Astrophysics Data System (ADS)

    Haveman, Shelley A.; Pedersen, Karsten

    2002-03-01

    Natural analogues allow scientists to investigate biogeochemical processes relevant to radioactive waste disposal that occur on time scales longer than those that may be studied by time-limited laboratory experiments. The Palmottu U-Th deposit in Finland and the Bangombé natural nuclear reactor in Gabon involve the study of natural uranium, and are both considered natural analogues for subsurface radioactive waste disposal. The microbial population naturally present in groundwater may affect the redox conditions, and hence, the radionuclide solubility and migration. Therefore, groundwater samples from the two sites were investigated for microbial populations. The total numbers of cells ranged from 10 4 to 10 6 cells ml -1. Iron-reducing bacteria (IRB) were the largest culturable microbial population in the Palmottu groundwater and were present at up to 1.3×10 5 cells ml -1. Sulfate-reducing bacteria (SRB) and acetogens could also be cultured from the Palmottu groundwater. The numbers of IRB and SRB were largest in groundwater with the lowest uranium concentrations. Removal of dissolved U(VI) from solution was concomitant with the growth of IRB enrichment cultures and the reduction of iron. The redox buffer in the Palmottu groundwater consists of iron and uranium species, both of which are affected by IRB. IRB and aerobic heterotrophs were cultured from the Bangombé groundwater, where redox potentials are buffered by iron and organic carbon species. Microbial populations similar to those found at Palmottu and Bangombé are found throughout the Fennoscandian Shield, a potential host rock for subsurface radioactive waste disposal. These results confirm that microorganisms can be expected to play a role in stabilizing radioactive waste disposed of in the subsurface by lowering redox potential and immobilizing radionuclides.

  13. Natural Bacterial Communities Serve as Quantitative Geochemical Biosensors

    PubMed Central

    Smith, Mark B.; Rocha, Andrea M.; Smillie, Chris S.; Olesen, Scott W.; Paradis, Charles; Wu, Liyou; Campbell, James H.; Fortney, Julian L.; Mehlhorn, Tonia L.; Lowe, Kenneth A.; Earles, Jennifer E.; Phillips, Jana; Joyner, Dominique C.; Elias, Dwayne A.; Bailey, Kathryn L.; Hurt, Richard A.; Preheim, Sarah P.; Sanders, Matthew C.; Yang, Joy; Mueller, Marcella A.; Brooks, Scott; Watson, David B.; Zhang, Ping; He, Zhili; Dubinsky, Eric A.; Adams, Paul D.; Arkin, Adam P.; Fields, Matthew W.; Zhou, Jizhong; Alm, Eric J.

    2015-01-01

    ABSTRACT Biological sensors can be engineered to measure a wide range of environmental conditions. Here we show that statistical analysis of DNA from natural microbial communities can be used to accurately identify environmental contaminants, including uranium and nitrate at a nuclear waste site. In addition to contamination, sequence data from the 16S rRNA gene alone can quantitatively predict a rich catalogue of 26 geochemical features collected from 93 wells with highly differing geochemistry characteristics. We extend this approach to identify sites contaminated with hydrocarbons from the Deepwater Horizon oil spill, finding that altered bacterial communities encode a memory of prior contamination, even after the contaminants themselves have been fully degraded. We show that the bacterial strains that are most useful for detecting oil and uranium are known to interact with these substrates, indicating that this statistical approach uncovers ecologically meaningful interactions consistent with previous experimental observations. Future efforts should focus on evaluating the geographical generalizability of these associations. Taken as a whole, these results indicate that ubiquitous, natural bacterial communities can be used as in situ environmental sensors that respond to and capture perturbations caused by human impacts. These in situ biosensors rely on environmental selection rather than directed engineering, and so this approach could be rapidly deployed and scaled as sequencing technology continues to become faster, simpler, and less expensive. PMID:25968645

  14. Natural bacterial communities serve as quantitative geochemical biosensors

    SciTech Connect

    Smith, Mark B.; Rocha, Andrea M.; Smillie, Chris S.; Olesen, Scott W.; Paradis, Charles; Wu, Liyou; Campbell, James H.; Fortney, Julian L.; Mehlhorn, Tonia L.; Lowe, Kenneth A.; Earles, Jennifer E.; Phillips, Jana; Techtmann, Steve M.; Joyner, Dominique C.; Elias, Dwayne A.; Bailey, Kathryn L.; Hurt, Richard A.; Preheim, Sarah P.; Sanders, Matthew C.; Yang, Joy; Mueller, Marcella A.; Brooks, Scott; Watson, David B.; Zhang, Ping; He, Zhili; Dubinsky, Eric A.; Adams, Paul D.; Arkin, Adam P.; Fields, Matthew W.; Zhou, Jizhong; Alm, Eric J.; Hazen, Terry C.

    2015-05-12

    Biological sensors can be engineered to measure a wide range of environmental conditions. Here we show that statistical analysis of DNA from natural microbial communities can be used to accurately identify environmental contaminants, including uranium and nitrate at a nuclear waste site. In addition to contamination, sequence data from the 16S rRNA gene alone can quantitatively predict a rich catalogue of 26 geochemical features collected from 93 wells with highly differing geochemistry characteristics. We extend this approach to identify sites contaminated with hydrocarbons from the Deepwater Horizon oil spill, finding that altered bacterial communities encode a memory of prior contamination, even after the contaminants themselves have been fully degraded. We show that the bacterial strains that are most useful for detecting oil and uranium are known to interact with these substrates, indicating that this statistical approach uncovers ecologically meaningful interactions consistent with previous experimental observations. Future efforts should focus on evaluating the geographical generalizability of these associations. Taken as a whole, these results indicate that ubiquitous, natural bacterial communities can be used as in situ environmental sensors that respond to and capture perturbations caused by human impacts. These in situ biosensors rely on environmental selection rather than directed engineering, and so this approach could be rapidly deployed and scaled as sequencing technology continues to become faster, simpler, and less expensive. Here we show that DNA from natural bacterial communities can be used as a quantitative biosensor to accurately distinguish unpolluted sites from those contaminated with uranium, nitrate, or oil. These results indicate that bacterial communities can be used as environmental sensors that respond to and capture perturbations caused by human impacts.

  15. Natural bacterial communities serve as quantitative geochemical biosensors

    DOE PAGESBeta

    Smith, Mark B.; Rocha, Andrea M.; Smillie, Chris S.; Olesen, Scott W.; Paradis, Charles; Wu, Liyou; Campbell, James H.; Fortney, Julian L.; Mehlhorn, Tonia L.; Lowe, Kenneth A.; et al

    2015-05-12

    Biological sensors can be engineered to measure a wide range of environmental conditions. Here we show that statistical analysis of DNA from natural microbial communities can be used to accurately identify environmental contaminants, including uranium and nitrate at a nuclear waste site. In addition to contamination, sequence data from the 16S rRNA gene alone can quantitatively predict a rich catalogue of 26 geochemical features collected from 93 wells with highly differing geochemistry characteristics. We extend this approach to identify sites contaminated with hydrocarbons from the Deepwater Horizon oil spill, finding that altered bacterial communities encode a memory of prior contamination,more » even after the contaminants themselves have been fully degraded. We show that the bacterial strains that are most useful for detecting oil and uranium are known to interact with these substrates, indicating that this statistical approach uncovers ecologically meaningful interactions consistent with previous experimental observations. Future efforts should focus on evaluating the geographical generalizability of these associations. Taken as a whole, these results indicate that ubiquitous, natural bacterial communities can be used as in situ environmental sensors that respond to and capture perturbations caused by human impacts. These in situ biosensors rely on environmental selection rather than directed engineering, and so this approach could be rapidly deployed and scaled as sequencing technology continues to become faster, simpler, and less expensive. Here we show that DNA from natural bacterial communities can be used as a quantitative biosensor to accurately distinguish unpolluted sites from those contaminated with uranium, nitrate, or oil. These results indicate that bacterial communities can be used as environmental sensors that respond to and capture perturbations caused by human impacts.« less

  16. Determination of geochemical and natural radioactivity characteristics in Bilecik Marble, Turkey

    NASA Astrophysics Data System (ADS)

    Yerel Kandemir, Suheyla; Ozbay, Nurgul

    2014-05-01

    Natural stones are one of the oldest known building materials. There are more than 400 natural stone in Turkey. Recently, the demand for the natural stone types in markets has been increasing rapidly. For this reason, the geochemical and natural radioactivity characteristics of natural stone are very important. Bilecik province is located at the northwest part of Turkey and it is surrounded by Sakarya, Bursa, Eskisehir and Kutahya city. Bilecik is one of the important marble industry regions of Turkey. Thus, the geochemical and natural radioactivity characteristics of Bilecik marble are very important. In this study, Bilecik marble was collected to determine the geochemistry and natural radioactivity. Then, analyses of geochemical and natural radioactivity in the marble samples are interpreted. ACKNOWLEDGMENT This study is supported by Bilecik Seyh Edebali University scientific project (Project Number =2011-02-BIL.03-04).

  17. Geochemical history of Chesapeake Bay: Natural and anthropogenic influences

    SciTech Connect

    Hill, J.M.; Park, J.; Brush, G.

    1995-12-31

    Sediment cores, 4--5 m in length were collected at six sites in the mainstem Chesapeake Bay, as part of the NOAA National Status and Trends Program. The cores were described, X-rayed, optically scanned, and analyzed for textural parameters, Si and Al, trace metals, AVS, soluble iron, total carbon, nitrogen and sulfur. In addition, the cores were dated using Pb 210, C 14, and high temporal resolution pollen dating techniques. The cores indicate changes in the geochemical environment of the northern Chesapeake Bay, from an environment dominated by marine geochemical processes to one dominated by estuarine processes; this transition occurred approximately in the late 1930`s. Accompanying this transition is enrichment of the trace metals, as normalized to Al. Data from the cores also indicate periodic anoxic events have occurred in the main stem of the Chesapeake Bay since the time from European settlement, based on sulfur speciation and the behavior of Mn in the sediments. The behavior of the trace metals, in regard to changes through time, is strongly dependent on location in the Bay, reflecting different sources materials, and differences in geochemical environments of deposition. Changes in geochemistry of most of the cores, at approximately the same date, tentatively indicate events with Baywide influence are recorded in the sediments of these cores.

  18. Synthesis and evaluation of immunostimulant plasmalogen lysophosphatidylethanolamine and analogues for natural killer T cells.

    PubMed

    Ni, Guanghui; Li, Zhiyuan; Liang, Kangjiang; Wu, Ting; De Libero, Gennaro; Xia, Chengfeng

    2014-06-01

    Plasmalogen lysophosphatidylethanolamine (pLPE) had been identified as a self antigen for natural killer T cells (NKT cells). It is very important in the development, maturation and activation of NKT cells in thymus. Besides, pLPE is a novel type of antigen for NKT cells. To evaluate the structure-activity relationship (SAR) of this new antigen, pLPE and its analogues referred to different aliphatic chains and linkages at the sn-1 position of the glycerol backbone were synthesized, and the biological activities of these analogues was characterized. It is discovered that the linkages between phosphate and lipid moiety are not important for the antigens' activities. The pLPE analogues 1, 3, 4, 7 and 9, which have additional double bonds on lipid parts, were identified as new NKT agonists. Moreover, the analogues 4, 7 and 9 were discovered as potent Th2 activators for NKT cells.

  19. Active experiments, magnetospheric modification, and a naturally occurring analogue

    NASA Technical Reports Server (NTRS)

    Kivelson, M. G.; Russell, C. T.

    1973-01-01

    Recently, a scheme has been proposed which would modify the magnetosphere by injecting plasma near the equator beyond the plasmapause and initiating wave-particle instabilities. The expected effects have been examined theoretically. Injection of plasma into this region is also a naturally occurring phenomenon produced by the cross-tail electric fields which are associated with geomagnetic activity. For further investigation of magnetospheric instabilities, the advantages of examining artificially injected plasma (control of time and location of injection and of the volume of plasma injected) contrast with the advantages of studying natural enhancements (no extra payload, frequent occurrence). Thus, the two types of experiments are complementary. In preliminary studies of natural plasma enhancements both ULF and ELF emissions have been observed. The ELF noise is consistent with generation by the electron cyclotron instability.

  20. Natural analogue synthesis report, TDR-NBS-GS-000027 rev00 icn02

    SciTech Connect

    Simmons, A.; Nieder-Westermann, G.; Stuckless, J.; Dobson, P.; Unger, A.J.A.; Kwicklis, E.; Lichtner, P.; Carey, B.; Wolde, G.; Murrel,M.; Kneafsey, T.J.; Meijer, A.; Faybishenko, B.

    2002-04-01

    The purpose of this report is to present analogue studies and literature reviews designed to provide qualitative and quantitative information to test and provide added confidence in process models abstracted for performance assessment (PA) and model predictions pertinent to PA. This report provides updates to studies presented in the Yucca Mountain Site Description (CRWMS M&O 2000 [151945], Section 13) and new examples gleaned from the literature, along with results of quantitative studies conducted specifically for the Yucca Mountain Site Characterization Project (YMP). The intent of the natural analogue studies was to collect corroborative evidence from analogues to demonstrate additional understanding of processes expected to occur during postclosure at a potential Yucca Mountain repository. The report focuses on key processes by providing observations and analyses of natural and anthropogenic (human-induced) systems to improve understanding and confidence in the operation of these processes under conditions similar to those that could occur in a nuclear waste repository. The process models include those that represent both engineered and natural barrier processes. A second purpose of this report is to document the various applications of natural analogues to geologic repository programs, focusing primarily on the way analogues have been used by the YMP. This report is limited to providing support for PA in a confirmatory manner and to providing corroborative inputs for process modeling activities. Section 1.7 discusses additional limitations of this report. Key topics for this report are analogues to emplacement drift degradation, waste form degradation, waste package degradation, degradation of other materials proposed for the engineered barrier, seepage into drifts, radionuclide flow and transport in the unsaturated zone (UZ), analogues to coupled thermal-hydrologic-mechanical-chemical processes, saturated zone (SZ) transport, impact of radionuclide release

  1. The development of structures in analogue and natural debris avalanches

    NASA Astrophysics Data System (ADS)

    Paguican, Engielle Mae; van Wyk de Vries, Benjamin; Mahar Francisco Lagmay, Alfredo; Grosse, Pablo

    2010-05-01

    All types of rockslide-debris avalanches present a plethora of internal structures that are also well observed on the surface. Many of these are seen as faults and folds that can be used to determine deformation history and kinematics. We present two sets of simple and well-constrained experiments of reduced basal friction laboratory rockslides, equivalent to a highly deformed simple shear layer, with plug-flow. These follow the original ramp-slide work of Shea and van Wyk de Vries (Geosphere, 2008). The experiments used a curved ramp where materials accelerate until reaching a gently-sloped depositional surface and a constantly inclined ramp with a more regular slope and longer slides. A detailed description of deposit structures, their sequential formation and morphology is then used to investigate the transport type and deformation chronology from slide initiation to runout stopping of avalanches. Results using a curved ramp show accumulation and thickening at where the slope decreases. The thickened mass then further remobilises and advances by secondary collapse of the mass. Such a stop-start process may be important in many mountainous avalanches where there are rapid changes in slope. The constantly inclined ramp shows shearing and extensional structures at the levees and a set of compression and extension structures in the middle. We noted that frontal accumulation during flow occurs as materials at the front move slower relative to those in the medial and proximal zones. This also leads to secondary frontal collapse, and helps to maintain a thicker mass that can flow further. Descriptions and analyses of these structures are then applied to the kinematics and dynamics of natural examples. We study the 2006 Guinsaugon Rockslide event in the Philippines and find that frontal accumulation and secondary avalanching had also occurred and were important in determining the distribution and runout of the mass. Frontal bulking and collapse may also have occurred at

  2. Multi-isotope tracing of CO2 leakage and water-rock interaction in a natural CCS analogue.

    NASA Astrophysics Data System (ADS)

    Kloppmann, Wolfram; Gemeni, Vasiliki; Lions, Julie; Koukouzas, Nikolaos; Humez, Pauline; Vasilatos, Charalampos; Millot, Romain; Pauwels, Hélène

    2015-04-01

    Natural analogues of CO2 accumulation and, potentially, leakage, provide a highly valuable opportunity to study (1) geochemical processes within a CO2-reservoir and the overlying aquifers or aquicludes, i.e. gas-water-rock interactions, (2) geology and tightness of reservoirs over geological timescales, (3) potential or real leakage pathways, (3) impact of leakage on shallow groundwater resources quality, and (4) direct and indirect geochemical indicators of gas leakage (Lions et al., 2014, Humez et al., 2014). The Florina Basin in NW Macedonia, Greece, contains a deep CO2-rich aquifer within a graben structure. The graben filling consists of highly heterogeneous Neogene clastic sediments constituted by components from the adjacent massifs including carbonates, schists, gneiss as well as some ultramafic volcanic rocks. Clay layers are observed that isolate hydraulically the deep, partly artesian aquifer. Organic matter, in form of lignite accumulations, is abundant in the Neogene series. The underlying bedrocks are metamorphic carbonates and silicate rocks. The origin of the CO2 accumulation is controversial (deep, partially mantle-derived D'Allessandro et al., 2008 or resulting from thermal decomposition of carbonates, Hatziyannis and Arvanitis, 2011). Groundwaters have been sampled from springs and borewells over 3 years at different depths. First results on major, minor and trace elements give evidence of water-rock interaction, mainly with carbonates but also with ultramafic components but do not indicate that CO2-seepage is the principal driver of those processes (Gemeni et al., submitted). Here we present isotope data on a selection of groundwaters (δ2H , δ18O, δ13CTDIC, 87Sr/86Sr, δ11B, δ7Li). Stable isotopes of water indicate paleo-recharge for some of the groundwaters, limited exchange with gaseous CO2 and, in one case, possibly thermal exchange processes with silicates. Sr isotope ratios vary between marine ratios and radiogenic values indicating

  3. Geochemical profile of a layered outcrop in the Atacama analogue using laser-induced breakdown spectroscopy: Implications for Curiosity investigations in Gale

    NASA Astrophysics Data System (ADS)

    Sobron, Pablo; Lefebvre, Catherine; Leveille, Richard; Koujelev, Alex; Haltigin, Timothy; Du, Hongwei; Wang, Alian; Cabrol, Nathalie; Zacny, Kris; Craft, Jack

    2013-05-01

    performed laboratory laser-induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy measurements on samples from a layered outcrop from the Atacama Desert, Chile. This outcrop is a terrestrial morphological and possibly mineralogical analogue for similar formations that will likely be investigated by the Curiosity rover at Gale Crater. Our results demonstrate that fast LIBS analysis can generate semiquantitative chemical profiles in subminute times using automated data processing tools. Therefore, the LIBS instrument can be an invaluable tactical tool on the Curiosity rover for remote, rapid geochemical survey of layered outcrops, thus serving daily operational needs. The derived chemical profiles, supported by the range of minerals identified by Raman spectroscopy, is consistent with the products of a continental evaporitic lake. In the framework of future surface exploration on Mars, a combined Raman/LIBS investigation may provide a rapid mineralogical/chemical evaluation of targets that can be useful for selecting samples to be eventually collected for sample return purposes or for selecting sample sites to be drilled in the search for astrobiology-relevant species.

  4. Synthetic analogues of the natural compound cryphonectric acid interfere with photosynthetic machinery through two different mechanisms.

    PubMed

    Teixeira, Róbson Ricardo; Pereira, Wagner Luiz; Tomaz, Deborah Campos; de Oliveira, Fabrício Marques; Giberti, Samuele; Forlani, Giuseppe

    2013-06-12

    A series of isobenzofuran-1(3H)-ones (phthalides), analogues of the naturally occurring phytotoxin cryphonectric acid, were designed, synthesized, and fully characterized by NMR, IR, and MS analyses. Their synthesis was achieved via condensation, aromatization, and acetylation reactions. The measurement of the electron transport chain in spinach chloroplasts showed that several derivatives are capable of interfering with the photosynthetic apparatus. Few of them were found to inhibit the basal rate, but a significant inhibition was brought about only at concentrations exceeding 50 μM. Some other analogues acted as uncouplers or energy transfer inhibitors, with a remarkably higher effectiveness. Isobenzofuranone addition to the culture medium inhibited the growth of the cyanobacterium Synechococcus elongatus , with patterns consistent with the effects measured in vitro upon isolated chloroplasts. The most active derivatives, being able to completely suppress algal growth at 20 μM, may represent structures to be exploited for the design of new active ingredients for weed control.

  5. [Reproduction of European bank vole (Myodes glareolus, Rodentia) under conditions of natural geochemical anomalies].

    PubMed

    Baĭtimirova, E A; Mamina, V P; Zhigal'skiĭ, O A

    2010-01-01

    Estimates of abundance, morpho-functional state of ovaries, potential and actual fecundity of European bank vole, Myodes glareolus, inhabiting the territories of natural geochemical anomalies that are situated over ultra-basic rock and have an excess content of chrome, nickel, and cobaltare obtained. The population adaptive response to extreme geochemical conditions that facilitates the species survival under unfavorable environmental conditions and is manifested through an increase in potential and actual fecundity, decline of pre-implantation mortality, and decrease in proportion of females with pre-implantation losses is revealed. It is shown that in anomalous areas the intensity of folliculogenesis in mature voles is independent of the population cycle phase. As for immature animals residing within geochemical anomalies, an increase in size and numbers of follicles in ovaries is observed which is indicative of maturation fastening. An increase in potential and actual fecundity, as well as changes in morpho-functional state of ovaries, can be interpreted as means of birth rate accelerating which is supposed to compensate high postnatal mortality and maintain population abundance.

  6. Non-Natural Sugar Analogues: Chemical Probes for Metabolic Oligosaccharide Engineering

    NASA Astrophysics Data System (ADS)

    Aich, Udayanath; Yarema, Kevin J.

    Metabolic oligosaccharide engineering (MOE) is a rapidly growing technology emerging from the field of chemical biology that allows novel chemical functionalities to be biosynthetically installed into the carbohydrates of living cells and animals. Since pioneering efforts to modulate sialic acid display through the use of non-natural N-acetyl-D-mannosamine (ManNAc) analogues were reported 15 years ago, monosaccharide probes have been developed to manipulate N-acetyl-D-galactosamine (GalNAc), N-acetyl-D-glucosamine (GlcNAc), and fucose-containing glycans. The 'first generation' of analogues, comprised of a series of ManNAc derivatives with elongated N-acyl chains, demonstrated pathway permissivity and the ability of this methodology to impinge on biological processes ranging from pathogen binding to gene expression and cell adhesion. Later analogues have incorporated chemical function groups including ketones, azides, thiols, and alkyne not normally found in carbohydrates. These groups serve as 'tags' for the subsequent use of chemoselective ligation reactions to further elaborate the chemical properties of the cell surface and thereby greatly expand the potential of MOE technology to offer control over biological processes.

  7. Structure activity relationship study of Mezzettiasides natural products and their four new disaccharide analogues for anticancer/antibacterial activity

    PubMed Central

    Bajaj, Sumit O.; Shi, Pei

    2014-01-01

    Ten members of the mezzettiaside family of natural products were synthesized and evaluated for anticancer and antibacterial activity. Complete anticancer (H460) and antibacterial (B. subtilis) activities for the ten natural products and four new analogues were found. Comparison to the cleistrioside and cleistetroside classes of natural products were made. PMID:25729554

  8. Gamma-ray characterization of uranium-series nuclides and its application to the study of the Pena Blanca natural analogue site, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Wong, Virgina

    Two natural analogue sites located in the Pena Blanca Uranium District, Chihuahua, Mexico were characterized for radionuclide mobility. Analogue I is used to assess the long-term behavior of uranium-series nuclides in a host rock and geochemical environment that is similar to the proposed high-level waste repository at Yucca Mountain, Nevada. Analogue II represents a former dump site to assess short-term radionuclide mobility. Gamma-ray spectroscopy analysis was used to measure radioactivity of the U-series nuclides. Samples analyzed from Analogue I consist of: (1) fracture-infillings associated with different alteration assemblages collected within and outside the breccia pipe from various levels of the deposit and (2) fracture-infillings collected along an east-west trending fracture which intersects the breccia pipe and extends into the host rock. Alteration mineralogy, established via X-ray diffraction analysis, consists of pure kaolinite, a mixture of Fe-oxyhydroxide (goethite, hematite) With inclusions of jarosite and alunite, and carbonates. Results from activity ratios of 230Th/238U versus 226Ra/230Th indicate that majority of the Fe-oxyhydroxides from the breccia zone show a slight disequilibrium with respect to Ra enrichment and U depletion. This observation is modeled as requiring a multiple-event history of U mobility. An amorphous Fe sample distal to the breccia zone shows similar behavior but to a greater extent. This extreme behavior is ascribed to initially low U content and greater late-stage U removal. Two Fe-oxyhydroxide samples from Within the breccia pipe also display multiple-event stages but exhibit both Ra and U leaching. This behavior is shared by Fe-oxyhydroxide samples collected inside and peripheral to the breccia zone from the east-west trending fracture. Finally, three samples, two Fe phase samples outside the breccia zone and a kaolinite inside the breccia zone, show Ra and U enrichment. Also, a distal Fe-oxyhydroxide sample from the

  9. Geochemical Responses to Anthropogenic and Natural Influences in Ebinur Lake Sediments of Arid Northwest China.

    PubMed

    Ma, Long; Wu, Jinglu; Abuduwaili, Jilili; Liu, Wen

    2016-01-01

    Geochemical concentrations were extracted for a short sediment core from Ebinur Lake, located in arid northwest China, and mathematical methods were used to demonstrate the complex pattern of the geochemical anomalies resulting from the temporal changes in natural and anthropogenic forces on the lake sediments. The first element assemblage (C1) (aluminum, potassium, iron, magnesium, beryllium, etc.) was predominantly terrigenous; among the assemblage, total phosphorus and titanium were generally consistent with aluminum except with regards to their surface sequences, which inferred the differences of source regions for terrigenous detrital material led to this change around ca. 2000AD. The second assemblage (C2) (calcium and strontium) was found to have a negative relationship with aluminum through a cluster analysis. The third assemblage (C3) included sodium and magnesium, which were influenced by the underwater lake environment and deposited in the Ebinur depression. The concentration ratio of C1/(C1+C2) was used as an indicator for denudation amount of detrital materials, which was supported by the values of magnetic susceptibility. The enrichment factors for heavy metals suggested that the influence of human activities on heavy-metal enrichment in Ebinur Lake region was not severe over the past century. Prior to the 1960s, geochemical indicators suggested a stable lacustrine environment with higher water levels. Beginning in the 1960s, high agricultural water demand resulted in rapid declines in lake water level, with subsequent increases of lake water salinity, as evidenced by enhanced sodium concentration in lake core sediments. During this period, anthropogenic activity also enhanced the intensity of weathering and the denudation of the Ebinur watershed. PMID:27176765

  10. Geochemical Responses to Anthropogenic and Natural Influences in Ebinur Lake Sediments of Arid Northwest China

    PubMed Central

    Wu, Jinglu; Abuduwaili, Jilili; Liu, Wen

    2016-01-01

    Geochemical concentrations were extracted for a short sediment core from Ebinur Lake, located in arid northwest China, and mathematical methods were used to demonstrate the complex pattern of the geochemical anomalies resulting from the temporal changes in natural and anthropogenic forces on the lake sediments. The first element assemblage (C1) (aluminum, potassium, iron, magnesium, beryllium, etc.) was predominantly terrigenous; among the assemblage, total phosphorus and titanium were generally consistent with aluminum except with regards to their surface sequences, which inferred the differences of source regions for terrigenous detrital material led to this change around ca. 2000AD. The second assemblage (C2) (calcium and strontium) was found to have a negative relationship with aluminum through a cluster analysis. The third assemblage (C3) included sodium and magnesium, which were influenced by the underwater lake environment and deposited in the Ebinur depression. The concentration ratio of C1/(C1+C2) was used as an indicator for denudation amount of detrital materials, which was supported by the values of magnetic susceptibility. The enrichment factors for heavy metals suggested that the influence of human activities on heavy-metal enrichment in Ebinur Lake region was not severe over the past century. Prior to the 1960s, geochemical indicators suggested a stable lacustrine environment with higher water levels. Beginning in the 1960s, high agricultural water demand resulted in rapid declines in lake water level, with subsequent increases of lake water salinity, as evidenced by enhanced sodium concentration in lake core sediments. During this period, anthropogenic activity also enhanced the intensity of weathering and the denudation of the Ebinur watershed. PMID:27176765

  11. Curcumin and its analogues: a potential natural compound against HIV infection and AIDS.

    PubMed

    Prasad, Sahdeo; Tyagi, Amit K

    2015-11-01

    No safe and effective cure currently exists for human immunodeficiency virus (HIV). However, antiretroviral therapy can prolong the lives of HIV patients and lowers the secondary infections. Natural compounds, which are considered to be pleiotropic molecules, could be useful against HIV. Curcumin, a yellow pigment present in the spice turmeric (Curcuma longa), can be used for the treatment of several diseases including HIV-AIDS because of its antioxidant, anti-inflammatory, anticancer, antiviral, and antibacterial nature. In this review we have summarized that how curcumin and its analogues inhibit the infection and replication of viral genes and prevent multiplicity of HIV. They are inhibitors of HIV protease and integrase. Curcumin also inhibits Tat transactivation of the HIV1-LTR genome, inflammatory molecules (interleukins, TNF-α, NF-κB, COX-2) and HIV associated various kinases including tyrosine kinase, PAK1, MAPK, PKC, cdk and others. In addition, curcumin enhances the effect of conventional therapeutic drugs and minimizes their side effects.

  12. Radiation-Induced Defects in Kaolinite as Tracers of Past Occurrence of Radionuclides in a Natural Analogue of High Level Nuclear Waste Repository

    NASA Astrophysics Data System (ADS)

    Allard, T.; Fourdrin, C.; Calas, G.

    2007-05-01

    Understanding the processes controlling migrations of radioelements at the Earth's surface is an important issue for the long-term safety assessment of high level nuclear waste repositories (HLNWR). Evidence of past occurrence and transfer of radionuclides can be found using radiation-induced defects in minerals. Clay minerals are particularly relevant because of their widespread occurrence at the Earth's surface and their finely divided nature which provides high contact area with radioactive fluids. Owing to its sensitivity to radiations, kaolinite can be used as natural, in situ dosimeter. Kaolinite is known to contain radiation-induced defects which are detected by Electron Paramagnetic Resonance. They are differentiated by their nature, their production kinetics and their thermal stability. One of these defects is stable at the scale of geological periods and provides a record of past radionuclide occurrence. Based on artificial irradiations, a methodology has been subsequently proposed to determine paleodose cumulated by kaolinite since its formation. The paleodose can be used to derive equivalent radioelement concentrations, provided that the age of kaolinite formation can be constrained. This allows quantitative reconstruction of past transfers of radioelements in natural systems. An example is given for the Nopal I U-deposit (Chihuahua, Mexico), hosted in hydrothermally altered volcanic tufs and considered as analogue of the Yucca Mountain site. The paleodoses experienced by kaolinites were determined from the concentration of defects and dosimetry parameters of experimental irradiations. Using few geochemical assumption, a equivalent U-content responsible for defects in kaolinite was calculated from the paleodose, a dose rate balance and model ages of kaolinites constrained by tectonic phases. In a former study, the ages were assumptions derived from regional tectonic events. In thepresent study, ages of mineralization events are measured from U

  13. In Vitro Neuroprotective and Anti-Inflammatory Activities of Natural and Semi-Synthetic Spirosteroid Analogues.

    PubMed

    García-Pupo, Laura; Zaldo-Castro, Armando; Exarchou, Vassiliki; Tacoronte-Morales, Juan Enrique; Pieters, Luc; Vanden Berghe, Wim; Nuñez-Figueredo, Yanier; Delgado-Hernández, René

    2016-01-01

    Two spirosteroid analogues were synthesized and evaluated for their in vitro neuroprotective activities in PC12 cells, against glutamate-induced excitotoxicity and mitochondrial damage in glucose deprivation conditions, as well as their anti-inflammatory potential in LPS/IFNγ-stimulated microglia primary cultures. We also evaluated the in vitro anti-excitotoxic and anti-inflammatory activities of natural and endogenous steroids. Our results show that the plant-derived steroid solasodine decreased PC12 glutamate-induced excitotoxicity, but not the cell death induced by mitochondrial damage and glucose deprivation. Among the two synthetic spirosteroid analogues, only the (25R)-5α-spirostan-3,6-one (S15) protected PC12 against ischemia-related in vitro models and inhibited NO production, as well as the release of IL-1β by stimulated primary microglia. These findings provide further insights into the role of specific modifications of the A and B rings of sapogenins for their neuroprotective potential. PMID:27483221

  14. Synthesis of C11-Desmethoxy Soraphen A1α: A Natural Product Analogue That Inhibits Acetyl-CoA Carboxylase

    PubMed Central

    2013-01-01

    A synthesis of C11-desmethoxy soraphen A1α is described that proceeds in just 14 steps from readily available starting materials. This natural product analogue was identified as a target of interest in a program aimed at identifying novel natural product-inspired inhibitors of acetyl-CoA carboxylase (ACC) as potential anticancer therapeutics. While describing the most efficient synthesis of a soraphen A1α analogue (total syntheses of the natural product have been reported that proceed in 25 to ≥40 linear steps), we also present data supporting the conclusion that C11-heteroatom functionality is a beneficial but unnecessary structural characteristic of soraphen A1α analogues for inhibiting ACC. PMID:24639892

  15. Geochemical evidence for possible natural migration of Marcellus Formation brine to shallow aquifers in Pennsylvania.

    PubMed

    Warner, Nathaniel R; Jackson, Robert B; Darrah, Thomas H; Osborn, Stephen G; Down, Adrian; Zhao, Kaiguang; White, Alissa; Vengosh, Avner

    2012-07-24

    The debate surrounding the safety of shale gas development in the Appalachian Basin has generated increased awareness of drinking water quality in rural communities. Concerns include the potential for migration of stray gas, metal-rich formation brines, and hydraulic fracturing and/or flowback fluids to drinking water aquifers. A critical question common to these environmental risks is the hydraulic connectivity between the shale gas formations and the overlying shallow drinking water aquifers. We present geochemical evidence from northeastern Pennsylvania showing that pathways, unrelated to recent drilling activities, exist in some locations between deep underlying formations and shallow drinking water aquifers. Integration of chemical data (Br, Cl, Na, Ba, Sr, and Li) and isotopic ratios ((87)Sr/(86)Sr, (2)H/H, (18)O/(16)O, and (228)Ra/(226)Ra) from this and previous studies in 426 shallow groundwater samples and 83 northern Appalachian brine samples suggest that mixing relationships between shallow ground water and a deep formation brine causes groundwater salinization in some locations. The strong geochemical fingerprint in the salinized (Cl > 20 mg/L) groundwater sampled from the Alluvium, Catskill, and Lock Haven aquifers suggests possible migration of Marcellus brine through naturally occurring pathways. The occurrences of saline water do not correlate with the location of shale-gas wells and are consistent with reported data before rapid shale-gas development in the region; however, the presence of these fluids suggests conductive pathways and specific geostructural and/or hydrodynamic regimes in northeastern Pennsylvania that are at increased risk for contamination of shallow drinking water resources, particularly by fugitive gases, because of natural hydraulic connections to deeper formations.

  16. Geochemical evidence for possible natural migration of Marcellus Formation brine to shallow aquifers in Pennsylvania

    PubMed Central

    Warner, Nathaniel R.; Jackson, Robert B.; Darrah, Thomas H.; Osborn, Stephen G.; Down, Adrian; Zhao, Kaiguang; White, Alissa; Vengosh, Avner

    2012-01-01

    The debate surrounding the safety of shale gas development in the Appalachian Basin has generated increased awareness of drinking water quality in rural communities. Concerns include the potential for migration of stray gas, metal-rich formation brines, and hydraulic fracturing and/or flowback fluids to drinking water aquifers. A critical question common to these environmental risks is the hydraulic connectivity between the shale gas formations and the overlying shallow drinking water aquifers. We present geochemical evidence from northeastern Pennsylvania showing that pathways, unrelated to recent drilling activities, exist in some locations between deep underlying formations and shallow drinking water aquifers. Integration of chemical data (Br, Cl, Na, Ba, Sr, and Li) and isotopic ratios (87Sr/86Sr, 2H/H, 18O/16O, and 228Ra/226Ra) from this and previous studies in 426 shallow groundwater samples and 83 northern Appalachian brine samples suggest that mixing relationships between shallow ground water and a deep formation brine causes groundwater salinization in some locations. The strong geochemical fingerprint in the salinized (Cl > 20 mg/L) groundwater sampled from the Alluvium, Catskill, and Lock Haven aquifers suggests possible migration of Marcellus brine through naturally occurring pathways. The occurrences of saline water do not correlate with the location of shale-gas wells and are consistent with reported data before rapid shale-gas development in the region; however, the presence of these fluids suggests conductive pathways and specific geostructural and/or hydrodynamic regimes in northeastern Pennsylvania that are at increased risk for contamination of shallow drinking water resources, particularly by fugitive gases, because of natural hydraulic connections to deeper formations. PMID:22778445

  17. Antibacterial Optimization of 4-Aminothiazolyl Analogues of the Natural Product GE2270 A: Identification of the Cycloalkylcarboxylic Acids

    SciTech Connect

    LaMarche, Matthew J.; Leeds, Jennifer A.; Amaral, Kerri; Brewer, Jason T.; Bushell, Simon M.; Dewhurst, Janetta M.; Dzink-Fox, JoAnne; Gangl, Eric; Goldovitz, Julie; Jain, Akash; Mullin, Steve; Neckermann, Georg; Osborne, Colin; Palestrant, Deborah; Patane, Michael A.; Rann, Elin M.; Sachdeva, Meena; Shao, Jian; Tiamfook, Stacey; Whitehead, Lewis; Yu, Donghui

    2012-11-09

    4-Aminothiazolyl analogues of the antibiotic natural product GE2270 A (1) were designed, synthesized, and optimized for their activity against Gram positive bacterial infections. Optimization efforts focused on improving the physicochemical properties (e.g., aqueous solubility and chemical stability) of the 4-aminothiazolyl natural product template while improving the in vitro and in vivo antibacterial activity. Structure-activity relationships were defined, and the solubility and efficacy profiles were improved over those of previous analogues and 1. These studies identified novel, potent, soluble, and efficacious elongation factor-Tu inhibitors, which bear cycloalkylcarboxylic acid side chains, and culminated in the selection of development candidates amide 48 and urethane 58.

  18. Nature or nurture of coplanar Tatooines: the aligned circumbinary Kuiper belt analogue around HD 131511

    NASA Astrophysics Data System (ADS)

    Kennedy, Grant M.

    2015-02-01

    A key discovery of the Kepler mission is of the circumbinary planets known as `Tatooines', which appear to be well aligned with their host stars' orbits. Whether this alignment is due to initially coplanar circumbinary planet-forming discs (i.e. nature), or subsequent alignment of initially misaligned discs by warping the inner disc or torquing the binary (i.e. nurture), is not known. Tests of which scenario dominates may be possible by observing circumbinary Kuiper belt analogues (`debris discs'), which trace the plane of the primordial disc. Here, the 140 au diameter circumbinary debris disc around HD 131511 is shown to be aligned to within 10° of the plane of the near edge-on 0.2 au binary orbit. The stellar equator is also consistent with being in this plane. If the primordial disc was massive enough to pull the binary into alignment, this outcome should be common and distinguishing nature versus nurture will be difficult. However, if only the inner disc becomes aligned with the binary, the HD 131511 system was never significantly misaligned. Given an initial misalignment, the ˜ Gyr main-sequence lifetime of the star allows secular perturbations to align the debris disc out to 100 au at the cost of an increased scaleheight. The observed debris disc scaleheight limits any misalignment to less than 25°. With only a handful known, many more such systems need to be characterized to help test whether the alignment of circumbinary planets is nature or nurture.

  19. Encapsulation of piceatannol, a naturally occurring hydroxylated analogue of resveratrol, by natural and modified cyclodextrins.

    PubMed

    Matencio, Adrián; García-Carmona, Francisco; López-Nicolás, José Manuel

    2016-05-18

    In this work, an in-depth study of the interaction between piceatannol (a type of stilbene with high biological activity) and different natural and modified cyclodextrins (CDs) is made, using steady state fluorescence. This bioactive molecule forms a 1 : 1 complex with all the natural (α-CD, β-CD and γ-CD) and modified (HP-β-CD, HE-β-CD and M-β-CD) CDs tested. Among natural CDs, the interaction of piceatannol with β-CD was the most efficient. However, the modified CDs showed higher encapsulation constants (KF) than β-CD, except M-β-CD; the highest KF being found for HP-β-CD (14 048 ± 702 M(-1)). The encapsulation of piceatannol in the internal cavity of CDs showed a strong dependence on pH and temperature. The interaction between HP-β-CD and piceatannol was less effective in the pH region where the stilbene begins to suffer the deprotonation of its hydroxyl group. Moreover, the values of KF decreased as the system temperature increased. To obtain information on the mechanism involved in the piceatannol affinity for CD, the thermodynamic parameters of the complexation (ΔH°, ΔS° and ΔG°) were studied, the results showed a negative entropy (-3.7 ± 0.2 J mol(-1) K(-1)), enthalpy (-24.6 ± 1.2 kJ mol(-1)) and Gibbs free energy change at 25 °C (-23.5 ± 1.2 J mol(-1)). Finally, molecular docking calculations provided further insights into how the different interactions influence the complexation constant. A high degree of correlation was observed between the computed scores and experimental values. PMID:27142512

  20. Novel Firmicutes Group Implicated in the Dechlorination of Two Chlorinated Xanthones, Analogues of Natural Organochlorines

    PubMed Central

    Krzmarzick, Mark J.; Miller, Hanna R.; Yan, Tao

    2014-01-01

    Although the abundance and diversity of natural organochlorines are well established, much is still unknown about the degradation of these compounds. Triplicate microcosms were used to determine whether, and which, bacterial communities could dechlorinate two chlorinated xanthones (2,7-dichloroxanthone and 5,7-dichloro-1,3-dihydroxylxanthone), analogues of a diverse class of natural organochlorines. According to quantitative-PCR (qPCR) results, several known dechlorinating genera were either not present or not enriched during dechlorination of the xanthones. Denaturing gradient gel electrophoresis, however, indicated that several Firmicutes were enriched in the dechlorinating cultures compared to triplicate controls amended with nonchlorinated xanthones. One such group, herein referred to as the Gopher group, was further studied with a novel qPCR method that confirmed enrichment of Gopher group 16S rRNA genes in the dechlorinating cultures. The enrichment of the Gopher group was again tested with two new sets of triplicate microcosms. Enrichment was observed during chlorinated xanthone dechlorination in one set of these triplicate microcosms. In the other set, two microcosms showed clear enrichment while a third did not. The Gopher group is a previously unidentified group of Firmicutes, distinct from but related to the Dehalobacter and Desulfitobacterium genera; this group also contains clones from at least four unique cultures capable of dechlorinating anthropogenic organochlorines that have been previously described in the literature. This study suggests that natural chlorinated xanthones may be effective biostimulants to enhance the remediation of pollutants and highlights the idea that novel genera of dechlorinators likely exist and may be active in bioremediation and the natural cycling of chlorine. PMID:24296507

  1. Using Natural Geochemical Tracers to Discern the Dominant Sources of Freshwater into Biscayne Bay, Southeast Florida

    NASA Astrophysics Data System (ADS)

    Stalker, J. C.; Price, R. M.; Swart, P. K.

    2005-05-01

    Biscayne Bay is a sub-tropical estuary located on the carbonate platform of south Florida. The water occupying Biscayne Bay is a balance of saltwater influx from the open ocean and freshwater inputs from precipitation, surface water runoff, and submarine groundwater discharge. The bays watershed includes a total of 3 million inhabitants, the major urban centers of Miami and Ft. Lauderdale, as well as the Everglades system. With the development of south Florida, the natural diffuse groundwater and stream flow into the bay has been replaced by a large system of canals and levees in an effort to control flooding and drain swampland. The Comprehensive Everglades Restoration Plan includes changes in the freshwater deliveries to Biscayne Bay from point-source discharges via canals to non-point source discharges via wetlands and groundwater flow. The balance of salinity in Biscayne Bay effects sensitive seagrass and tidal ecosystems including numerous species of corals and other biota. A comprehensive understanding of the flow of freshwater into the bay is crucial to future planned developments and restorations. The goal of this study is to use naturally occurring geochemical constituents as tracers to identify and quantify the sources of freshwater, i.e. rainfall, canal flow, and groundwater, discharge to Biscayne Bay. In this study, discrete samples of precipitation, canal water, terrestrial groundwater, marine groundwater, and bay surface water are collected monthly and analyzed for the stable isotopes of hydrogen and oxygen as well as for major cations and anions. Initial results indicate that fresh groundwater has an isotopic signature (del 18O = -2.66 per mil, del D, -7.60 per mil) similar to rainfall (del 18O = -2.86 per mil, del D =-4.78 per mil). In contrast canal water has a heavy isotopic signature (del 18O = -0.46 per mil, del D = -2.48 per mil) due to evaporation. Thus it is possible to use stable isotopes of oxygen and hydrogen to separate canal water from

  2. Restoration of estuarine wetlands via "managed realignment": the use of natural analogues.

    NASA Astrophysics Data System (ADS)

    Cundy, A.

    2003-04-01

    A proposed management response to rising sea-levels for low-relief coastal areas is the managed-realignment approach, where existing coastal defences are repositioned landward, and protective wetlands allowed to develop on the abandoned land. This technique has been applied with varying degrees of success at a number of coastal sites, and, in the U.K. at least, its use is increasing as coastal management authorities move away from hard engineering approaches towards more "natural" coastal and floodplain management. Studies of the response of low-lying coastal areas to the managed-realignment approach, and the subsequent restoration of intertidal wetlands, have tended to rely on short-term (< 5 years) studies of erosion and accretion, vegetation change, and changes in sediment chemistry. While the short-term response to breaching is important, it is essential to complement these studies with an understanding of the medium-term (decadal) response of low-lying coasts to sudden inundation to allow effective site selection and management. This medium-term response may be assessed using sedimentary and geomorphological studies at coastal sites which have been historically breached and flooded, which provide natural analogues for the managed realignment process. This paper illustrates this approach using data from two contrasting sites in southern England (Pagham Harbour and part of the Hamble estuary), which were flooded in the early 20th century following breaching of flood defences. Sediments at both sites retain a record of environmental change following marine inundation, and sedimentary studies, combined with documentary evidence, have been used to examine post-breaching marsh stability, variations in sediment accumulation rate, and vegetation colonisation and dieback over varying timescales. Historically-breached sites such as Pagham Harbour and the Hamble estuary are relatively common around European coasts, and these provide important natural laboratories within

  3. Heterogeneous seepage at the Nopal I natural analogue site, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Dobson, Patrick F.; Ghezzehei, Teamrat A.; Cook, Paul J.; Rodríguez-Pineda, J. Alfredo; Villalba, Lourdes; de La Garza, Rodrigo

    2012-02-01

    A study of seepage occurring in an adit at the Nopal I uranium mine in Chihuahua, Mexico, was conducted as part of an integrated natural analogue study to evaluate the effects of infiltration and seepage on the mobilization and transport of radionuclides. An instrumented seepage collection system and local automated weather station permit direct correlation between local precipitation events and seepage. Field observations recorded between April 2005 and December 2006 indicate that seepage is highly heterogeneous with respect to time, location, and quantity. Seepage, precipitation, and fracture data were used to test two hypotheses: (1) that fast flow seepage is triggered by large precipitation events, and (2) that an increased abundance of fractures and/or fracture intersections leads to higher seepage volumes. A few zones in the back adit recorded elevated seepage volumes immediately following large (>20 mm/day) precipitation events, with transit times of less than 4 h through the 8-m thick rock mass. In most locations, there is a 1-6 month time lag between the onset of the rainy season and seepage, with longer times observed for the front adit. There is a less clear-cut relation between fracture abundance and seepage volume; processes such as evaporation and surface flow along the ceiling may also influence seepage.

  4. Heterogeneous seepage at the Nopal I natural analogue site, Chihuahua, Mexico

    SciTech Connect

    Dobson, Patrick F.; Cook, Paul J.; Ghezzehei, Teamrat A.; Rodriguez, J. Alfredo; Villalba, Lourdes; de la Garza, Rodrigo

    2008-10-25

    An integrated field, laboratory, and modeling study of the Pena Blanca (Chihuahua, Mexico) natural analogue site is being conducted to evaluate processes that control the mobilization and transport of radionuclides from a uranium ore deposit. One component of this study is an evaluation of the potential for radionuclide transport through the unsaturated zone (UZ) via a seepage study in an adit at the Nopal I uranium mine, excavated 10 m below a mined level surface. Seasonal rainfall on the exposed level surface infiltrates into the fractured rhyolitic ash-flow tuff and seeps into the adit. An instrumented seepage collection system and local automated weather station permit direct correlation between local precipitation events and seepage within the Nopal I +00 adit. Monitoring of seepage within the adit between April 2005 and December 2006 indicates that seepage is highly heterogeneous with respect to time, location, and quantity. Within the back adit area, a few zones where large volumes of water have been collected are linked to fast flow path fractures (0-4 h transit times) presumably associated with focused flow. In most locations, however, there is a 1-6 month time lag between major precipitation events and seepage within the adit, with longer residence times observed for the front adit area. Seepage data obtained from this study will be used to provide input to flow and transport models being developed for the Nopal I hydrogeologic system.

  5. Characterization of the Pseudocapacitive Nature of Surface Bound Prussian Blue Analogues

    NASA Astrophysics Data System (ADS)

    Clark, Daniel; Hampton, Jennifer

    With the increased use of intermittent renewable energy sources, more efficient methods of energy storage must be explored. Electrochemical capacitors provide a larger volumetric charge density than physical capacitors while maintaining fast charge and discharge rates. Prussian Blue analogues (nickel and cobalt hexacyanoferrate) are ideal pseudocapacitors for frequent charge and discharge cycles since the crystalline structure does not physically change during switching, causing less stress on the film. This project examines the charge transfer and diffusion coefficients for nickel and nickel-cobalt thin films modified with potassium hexacyanoferrate. The films were examined using a scanning electron microscope, an atomic force microscope and an electrochemical workstation to determine their composition, topography and psuedocapacitive nature. Preliminary data suggest that nickel-cobalt films have a larger quantity of charge and have a lower diffusion coefficient per charge than nickel films. This work is supported by the Hope College Nyenhuis Faculty Development Fund, the Hope College Department of Physics Guess Research Fund, and the National Science Foundation under Grants RUI-DMR-1104725, MRI-CHE-0959282, and MRI-CHE-1126462.

  6. Structural and Biochemical Characterization of the Interaction of Tubulin with Potent Natural Analogues of Podophyllotoxin.

    PubMed

    Antúnez-Mojica, Mayra; Rodríguez-Salarichs, Javier; Redondo-Horcajo, Mariano; León, Alejandra; Barasoain, Isabel; Canales, Ángeles; Cañada, F J; Jiménez-Barbero, Jesús; Alvarez, Laura; Díaz, J Fernando

    2016-08-26

    Four natural analogues of podophyllotoxin obtained from the Mexican medicinal plant Bursera fagaroides, namely, acetyl podophyllotoxin (2), 5'-desmethoxy-β-peltatin A methyl ether (3), 7',8'-dehydro acetyl podophyllotoxin (4), and burseranin (5), have been characterized, and their interactions with tubulin have been investigated. Cytotoxic activity measurements, followed by immunofluorescence microscopy and flow cytometry studies, demonstrated that these compounds disrupt microtubule networks in cells and cause cell cycle arrest in the G2/M phase in the A549 cell line. A tubulin binding assay showed that compounds 1-4 were potent assembly inhibitors, displaying binding to the colchicine site with Kb values ranging from 11.75 to 185.0 × 10(5) M(-1). In contrast, burseranin (5) was not able to inhibit tubulin assembly. From the structural perspective, the ligand-binding epitopes of compounds 1-3 have been mapped using STD-NMR, showing that B and E rings are the major points for interaction with the protein. The obtained results indicate that the inhibition of tubulin assembly of this family of compounds is more effective when there are at least two methoxyl groups at the E ring, along with a trans configuration of the lactone ring in the aryltetralin lignan core. PMID:27518758

  7. The antimicrobial natural product chuangxinmycin and some synthetic analogues are potent and selective inhibitors of bacterial tryptophanyl tRNA synthetase.

    PubMed

    Brown, Murray J; Carter, Paul S; Fenwick, Ashley S; Fosberry, Andrew P; Hamprecht, Dieter W; Hibbs, Martin J; Jarvest, Richard L; Mensah, Lucy; Milner, Peter H; O'Hanlon, Peter J; Pope, Andrew J; Richardson, Christine M; West, Andrew; Witty, David R

    2002-11-01

    The antimicrobial natural product chuangxinmycin has been found to be a potent and selective inhibitor of bacterial tryptophanyl tRNA synthetase (WRS). A number of analogues have been synthesised. The interaction with WRS appears to be highly constrained, as only sterically smaller analogues afforded significant inhibition. The only analogue to show inhibition comparable to chuangxinmycin also had antibacterial activity. WRS inhibition may contribute to the antibacterial action of chuangxinmycin.

  8. The effect of sterilization on biological, organic geochemical and morphological information in natural samples

    NASA Technical Reports Server (NTRS)

    Hochstein, L. I.; Kvenvolden, K. A.; Philpott, D. E.

    1974-01-01

    The loss of biological, organic geochemical, and morphological science information that may occur should a Mars surface sample be sterilized prior to return to earth is examined. Results of experimental studies are summarized.

  9. Non-Reductive Strategies for U Sequestration: Natural Analogues and Practical Application

    NASA Astrophysics Data System (ADS)

    Maher, K.; Bethke, C. M.; Massey, M. S.

    2011-12-01

    A number of strategies have been proposed for the in situ remediation of U contaminated zones, including bioreduction, permeable reactive barriers, and incorporation into secondary phases such as phosphates. An alternative approach is to sequester U within amorphous Si phases such as opaline silica. We have investigated the isotopic and major element composition and structure of naturally occurring U-rich opaline silica in semi-arid soil environments across the western United States. These phases constitute a large natural reservoir of sequestered U. By combining these observations with geochemical considerations, we propose a remedial strategy for sequestering U in amorphous silica. The U-rich opal occurs as laminations, veins, and coatings on clasts in soils developed on a range of parent materials. U-rich opal deposits are also found as speleothems in caves, as silica-rich spring deposits, and as cavity fillings and hydrothermal veins in volcanic tuffs. Measurements of U, Th and Pb isotopes reveal the age of the opaline silica, demonstrating the long-term stability of U sequestration in open chemical environments. The isotopic data also suggest that opaline silica will retain the majority of the initial U over millions of years. U in naturally occurring opal generally ranges between 200 to 1000 ppm. In contrast, co-existing calcite contains less than 100 ppb U. From pore water chemistry, the distribution coefficient for U incorporation into opaline silica is approximately 20, whereas the coefficient for calcite is typically between 0.2 and 1. X-ray absorption spectroscopy investigations confirm that hexavalent U is incorporated in amorphous silica as the UO22+ ion. Coexisting Fe-oxides provide a further sink for sequestering UO22+ from the pore water. However, preliminary calculations suggest that incorporation of U into amorphous silica may be a dominant mechanism for isolating UO22+from groundwater over long time scales. Nature's mechanism for sequestering UO

  10. Determination of transport rates in the Yellow River Bohai Sea mixing zone via natural geochemical tracers

    NASA Astrophysics Data System (ADS)

    Peterson, Richard N.; Burnett, William C.; Taniguchi, Makoto; Chen, Jianyao; Santos, Isaac R.; Misra, Sambuddha

    2008-11-01

    In light of the current problems facing the Yellow River and surrounding areas (e.g., periods of zero river discharge, increasing nitrate concentrations of the Bohai Sea), we examined the coastal mixing dynamics around the mouth of the Yellow River. Naturally occurring radium isotopes ( 223Ra, 224Ra, 226Ra, and 228Ra) and other geochemical tracers (Ba, Si, and salinity) were employed to determine river plume transport scales and rates. Barium and radium exhibit elevated concentrations within the salinity gradient where they are desorbed from particles via ion-exchange. Once they are added to the system, they decrease offshore from dilution with lower concentration Bohai Sea water, and in the case of 224Ra and 223Ra, by radioactive decay. Using radium "ages" to assess the dissolved material transport scales and rates proved to be a useful tool in this environment. The ages based on the 224Ra/ 228Ra activity ratio increased gradually until salinities reached ˜25 when they rapidly increased due to decreased mixing at higher salinities. Integrated net transport rates through the salinity front ranged from 1.4 to 1.6 cm/s and did not vary significantly with river discharge. Thus, tidal mixing appears to dominate in this system, at least over the range of discharges investigated (80-600 m 3/s). Determining the temporal scale of flow across the coastal zone in this region is a valuable first step toward examining whether the Yellow River is contributing to the increasing inorganic nitrogen concentrations in the central Bohai Sea.

  11. Natural analogues for CO2 storage sites - analysis of a global dataset

    NASA Astrophysics Data System (ADS)

    Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, R. Stuart

    2013-04-01

    Carbon Capture and Storage is the only industrial scale technology currently available to reduce CO2 emissions from fossil-fuelled power plants and large industrial source to the atmosphere and thus mitigate climate change. CO2 is captured at the source and transported to subsurface storage sites, such as depleted oil and gas fields or saline aquifers. In order to have an effect on emissions and to be considered safe it is crucial that the amount of CO2 leaking from storage sites to shallow aquifers or the surface remains very low (<1% over 1000 years). Some process that influence the safety of a reservoir, such as CO2-rock-brine interactions, can be studied using experiments on both laboratory and field-scale. However, long-term processes such as the development of leakage pathways can only be understood by either predictive modelling or by studying natural CO2 reservoirs as analogues for long term CO2 storage sites. Natural CO2 reservoirs have similar geological trapping mechanisms as anticipated for CO2 storage sites and often have held CO2 for a geological period of time (millions of years) without any indication for leakage. Yet, migration of CO2 from reservoirs to the surface is also common and evidenced by gas seeps such as springs and soil degassing. We have compiled and analysed a dataset comprising of more than 50 natural CO2 reservoirs from different settings all around the globe to provide an overview of the factors that are important for the retention of CO2 in the subsurface and what processes lead to leakage of CO2 from the reservoir. Initial results indicate that if the reservoir is found to be leaking, CO2 migration is along faults and not through caprock layers. This indicates that faults act as fluid pathways and play an important role when characterizing a storage site. Additionally, it appears that overpressure of the overburden and the state of CO2 in the reservoir influence the likelihood of migration and hence the safety of a reservoir.

  12. Natural analogue of CO2 dispersion at deep-sea hydrothermal system

    NASA Astrophysics Data System (ADS)

    Shitashima, K.; Maeda, Y.; Ohsumi, T.

    2006-12-01

    CO2 ocean sequestration is being investigated as one of possible options to limit the accumulation of anthropogenic CO2 into the atmosphere. To investigate the appropriateness of CO2 ocean sequestration, the observations for dispersion behavior of sequestrated CO2 into the ocean and influence of a high CO2 environment upon the ocean including marine ecosystem are important. Hydrothermal vent fluids are highly enriched in CO2 and the CO2 rich fluids are released into the ocean as a hydrothermal plume. Especially, the emission of hydrothermal-related liquid CO2 from the sea floor at about 1500m depth was discovered at the Okinawa Trough and Mariana Trough. At these areas, it is considered that the liquid CO2 rises up to shallow depth as a CO2 droplet and that the rising CO2 droplet dissolves gradually in ambient seawater. Deep-sea hydrothermal systems are suitable for natural analogue of CO2 dispersion in the ocean. New cost-effective observation techniques to monitor the dispersion of CO2 were developed. The in-situ pH/pCO2 sensor is high precision in-situ measurement technology of pH and pCO2 in seawater. This sensor can detect precisely and rapidly the changes of pH and pCO2 derived from high CO2. The towing multi-layer monitoring system is observation technology of CO2 dispersion in the ocean. This system can observe the dispersion behavior of CO2 by towing several in-situ sensors and SSBL transponders in the high CO2 plume. The in-situ pH/pCO2 sensor is installed to each transponder of the towing multi-layer monitoring system and in-situ data can be monitored by sound communication in real time on board. We will report the results of an application of these observation techniques to the deep-sea hydrothermal system.

  13. Fe and O isotope composition of meteorite fusion crusts: Possible natural analogues to chondrule formation?

    NASA Astrophysics Data System (ADS)

    Hezel, Dominik C.; Poole, Graeme M.; Hoyes, Jack; Coles, Barry J.; Unsworth, Catherine; Albrecht, Nina; Smith, Caroline; RehkäMper, Mark; Pack, Andreas; Genge, Matthew; Russell, Sara S.

    2015-02-01

    Meteorite fusion crust formation is a brief event in a high-temperature (2000-12,000 K) and high-pressure (2-5 MPa) regime. We studied fusion crusts and bulk samples of 10 ordinary chondrite falls and 10 ordinary chondrite finds. The fusion crusts show a typical layering and most contain vesicles. All fusion crusts are enriched in heavy Fe isotopes, with δ56Fe values up to +0.35‰ relative to the solar system mean. On average, the δ56Fe of fusion crusts from finds is +0.23‰, which is 0.08‰ higher than the average from falls (+0.15‰). Higher δ56Fe in fusion crusts of finds correlate with bulk chondrite enrichments in mobile elements such as Ba and Sr. The δ56Fe signature of meteorite fusion crusts was produced by two processes (1) evaporation during atmospheric entry and (2) terrestrial weathering. Fusion crusts have either the same or higher δ18O (0.9-1.5‰) than their host chondrites, and the same is true for Δ17O. The differences in bulk chondrite and fusion crust oxygen isotope composition are explained by exchange of oxygen between the molten surface of the meteorites with the atmosphere and weathering. Meteorite fusion crust formation is qualitatively similar to conditions of chondrule formation. Therefore, fusion crusts may, at least to some extent, serve as a natural analogue to chondrule formation processes. Meteorite fusion crust and chondrules exhibit a similar extent of Fe isotope fractionation, supporting the idea that the Fe isotope signature of chondrules was established in a high-pressure environment that prevented large isotope fractionations. The exchange of O between a chondrule melt and an 16O-poor nebula as the cause for the observed nonmass dependent O isotope compositions in chondrules is supported by the same process, although to a much lower extent, in meteorite fusion crusts.

  14. The Werkendam natural CO2 accumulation: An analogue for CO2 storage in depleted oil reservoirs

    NASA Astrophysics Data System (ADS)

    Bertier, Pieter; Busch, Andreas; Hangx, Suzanne; Kampman, Niko; Nover, Georg; Stanjek, Helge; Weniger, Philipp

    2015-04-01

    The Werkendam natural CO2 accumulation is hosted in the Röt (Early Triassic) sandstone of the West Netherlands Basin, at a depth of 2.8 km, about 20 km south-east of Rotterdam (NL). This reservoir, in a fault-bound structure, was oil-filled prior to charging with magmatic CO2 in the early Cretaceous. It therefore offers a unique opportunity to study long-term CO2-water-rock interactions in the presence of oil. This contribution will present the results of a detailed mineralogical and geochemical characterisation of core sections from the Werkendam CO2 reservoir and an adjacent, stratigraphically equivalent aquifer. X-ray diffraction combined with X-ray fluorescence spectrometry revealed that the reservoir samples contain substantially more feldspar and more barite and siderite than those from the aquifer, while the latter have higher hematite contents. These differences are attributed to the effects hydrocarbons and related fluids on diagenesis in the closed system of the CO2 reservoir versus the open-system of the aquifer. Petrophysical analyses yielded overall higher and more anisotropic permeability for the reservoir samples, while the porosity is overall not significantly different from that of their aquifer equivalents. The differences are most pronounced in coarse-grained sandstones. These have low anhydrite contents and contain traces of calcite, while all other analyzed samples contain abundant anhydrite, dolomite/ankerite and siderite, but no calcite. Detailed petrography revealed mm-sized zones of excessive primary porosity. These are attributed to CO2-induced dissolution of precompactional, grain-replacive anhydrite cement. Diagenetic dolomite/ankerite crystals are covered by anhedral, epitaxial ankerite, separated from the crystals by bitumen coats. Since these carbonates were oil-wet before CO2-charging, the overgrowths are interpreted to have grown after CO2-charging. Their anhedral habit suggests growth in a 2-phase water-CO2 system. Isotopic

  15. A natural analogue for CO2 leakage: The release and fate of CO2 at the Jan Mayen vent fields (AMOR)

    NASA Astrophysics Data System (ADS)

    Baumberger, T.; Lilley, M. D.; Pedersen, R. B.; Thorseth, I. H.

    2013-12-01

    Carbon dioxide capture and storage (CCS) is seen as a new possible technique for reducing the emission of industrial CO2 to the atmosphere. To evaluate the risks of sub-seabed CO2 storage, the European Commission is supporting the international and multi-disciplinary ECO2 project. Among other objectives, this project is dealing with evaluating the likelihood of leakage and the resulting possible impacts on marine ecosystems. In the framework of the ECO2 project, the release and dispersal of CO2 have been studied at several natural seep sites. In this study, we present geochemical data collected at the natural CO2 leakage analogue, Jan Mayen vent fields (JMVF). The basalt-hosted JMVF are located at 71° N on the southern end of the ultra-slow spreading Mohns Ridge, which is part of the Arctic Mid-Ocean Ridge (AMOR) system. The JMVF are composed of several venting sites, spread over a large area. These venting areas include focused high-temperature venting and diffuse low-temperature fluid flow vents as well as areas where free gas bubbles are released. Over the past few years, we have repeatedly visited and extensively sampled these vent fields to study the release and fate of CO2 in this natural seep area. One of our main objectives was to constrain the CO2 content of the widely emitted gas and to study its dispersion and fate in the water column. We have also investigated hydrate formation, which is observed at various locations. The venting fluids are chemically characterized by CO2 concentrations of up to 110 mmol/kg, having an associated isotopic composition representing a mantle carbon source. Thus, the CO2 concentrations measured at the JMVF represent the high-end compared to the concentration range of most other basalt-hosted hydrothermal mid-ocean ridge systems. Even though the concentrations of the emitted CO2 vary over time and with the type of venting (focused flow, diffuse flow or bubbles), the overall release is continuously high. The dispersion of the

  16. Preliminary delineation of natural geochemical reactions, Snake River Plain aquifer system, Idaho National Engineering Laboratory and vicinity, Idaho

    SciTech Connect

    Knobel, L.L.; Bartholomay, R.C.; Orr, B.R.

    1997-05-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, is conducting a study to determine the natural geochemistry of the Snake River Plain aquifer system at the Idaho National Engineering Laboratory (INEL), Idaho. As part of this study, a group of geochemical reactions that partially control the natural chemistry of ground water at the INEL were identified. Mineralogy of the aquifer matrix was determined using X-ray diffraction and thin-section analysis and theoretical stabilities of the minerals were used to identify potential solid-phase reactants and products of the reactions. The reactants and products that have an important contribution to the natural geochemistry include labradorite, olivine, pyroxene, smectite, calcite, ferric oxyhydroxide, and several silica phases. To further identify the reactions, analyses of 22 representative water samples from sites tapping the Snake River Plain aquifer system were used to determine the thermodynamic condition of the ground water relative to the minerals in the framework of the aquifer system. Principal reactions modifying the natural geochemical system include congruent dissolution of olivine, diopside, amorphous silica, and anhydrite; incongruent dissolution of labradorite with calcium montmorillonite as a residual product; precipitation of calcite and ferric oxyhydroxide; and oxidation of ferrous iron to ferric iron. Cation exchange reactions retard the downward movement of heavy, multivalent waste constituents where infiltration ponds are used for waste disposal.

  17. Learning about crustal CO2 migration and leakage using natural analogues

    NASA Astrophysics Data System (ADS)

    Battani, A.; Jeandel, E.; Sarda, P.; Deville, E.

    2007-12-01

    CO2 gas samples and continental carbonates (travertines) were collected in different places of the French carbogaseous province. We performed analyses of noble gases and associated major compounds (mainly CO2) with d13C(CO2) isotopic analyses. We also made d13C and d18O measurements on the travertines present in all different sampled places to determine wether a significant part of the CO2 leaking could be trapped at the Earth surface. We wanted to test if travertines could be an indicator of the history of the system leakage, as they are potentialy datable. The main purpose of this study is to determine, using natural analogues, which context is most favourable for future CO2 storage. We collected seven gas samples from natural bubbling sources and geysers near Sainte Marguerite, Massif central, France. This area is known to present an important heat flow anomaly, due to the probable existence of a mantle plume below. The site exhibits many CO2-rich water wells associated with travertines rocks. We analysed the gas which is composed mainly of CO2 with a d13C (CO2) of around -5° compatible with a mantle-derived origin. The noble gas results show helium concentrations in the range of 0.28 to 8.22 ppm, with 5 samples lower than the atmospheric helium concentration of 5.24 ppm. However, within these samples, the 4He/20Ne ratios range from 2.12 to 198 and are all greater than air value of 0.288; thus air contamination can be discarded. The most intriguing result is that all our samples exhibit high and relatively homogeneous values of R/Ra, around 3.5 - 4, implying a large contribution of mantle-derived helium (R/Ra = 8 for the upper mantle) ) to the total budget of this gas. The neon and argon isotopic ratios are close to the atmospheric values, suggesting a small, if any, crustal contribution and an important Air Saturated Water (ASW) contribution, in agreement with the hydrothermalism of the area. To our knowledge, it is the first time that so low helium

  18. A comparative study on the crystal structure of bicycle analogues to the natural phytotoxin helminthosporins

    NASA Astrophysics Data System (ADS)

    Barbosa, Luiz Cláudio de Almeida; Teixeira, Robson Ricardo; Nogueira, Leonardo Brandão; Maltha, Celia Regina Alvares; Doriguetto, Antônio Carlos; Martins, Felipe Terra

    2016-02-01

    Herein we described structural insights of a series of analogues to helminthosporin phytotoxins. The key reaction used to prepare the compounds corresponded to the [3 + 4] cycloaddition between the oxyallyl cation generated from 2,4-dibromopentan-3-one and different furans. Their structures were confirmed upon IR, NMR and X-ray diffraction analyses. While bicycles 7, 8 and 9 crystallize in the centrosymmetric monoclinic space group P21/c, compound 10 was solved in the noncentrosymmetric orthorhombic space group P212121. The solid materials obtained were shown to be racemic crystals (7, 8, 9) or racemic conglomerate (10). In all compounds, there is formation of a bicycle featured by fused tetrahydropyranone and 2,5-dihydrofuran rings. They adopt chair and envelope conformations, respectively. Crystal packing of all compounds is stabilized through C-H•••O contacts. Conformational aspects as well as similarities and differences among the crystal structures of the synthesized analogues are discussed.

  19. Analogue modelling of inclined, brittle-ductile transpression: Testing analytical models through natural shear zones (external Betics)

    NASA Astrophysics Data System (ADS)

    Barcos, L.; Díaz-Azpiroz, M.; Balanyá, J. C.; Expósito, I.; Jiménez-Bonilla, A.; Faccenna, C.

    2016-07-01

    The combination of analytical and analogue models gives new opportunities to better understand the kinematic parameters controlling the evolution of transpression zones. In this work, we carried out a set of analogue models using the kinematic parameters of transpressional deformation obtained by applying a general triclinic transpression analytical model to a tabular-shaped shear zone in the external Betic Chain (Torcal de Antequera massif). According to the results of the analytical model, we used two oblique convergence angles to reproduce the main structural and kinematic features of structural domains observed within the Torcal de Antequera massif (α = 15° for the outer domains and α = 30° for the inner domain). Two parallel inclined backstops (one fixed and the other mobile) reproduce the geometry of the shear zone walls of the natural case. Additionally, we applied digital particle image velocimetry (PIV) method to calculate the velocity field of the incremental deformation. Our results suggest that the spatial distribution of the main structures observed in the Torcal de Antequera massif reflects different modes of strain partitioning and strain localization between two domain types, which are related to the variation in the oblique convergence angle and the presence of steep planar velocity - and rheological - discontinuities (the shear zone walls in the natural case). In the 15° model, strain partitioning is simple and strain localization is high: a single narrow shear zone is developed close and parallel to the fixed backstop, bounded by strike-slip faults and internally deformed by R and P shears. In the 30° model, strain partitioning is strong, generating regularly spaced oblique-to-the backstops thrusts and strike-slip faults. At final stages of the 30° experiment, deformation affects the entire model box. Our results show that the application of analytical modelling to natural transpressive zones related to upper crustal deformation

  20. The project De Caldas International Project: An example of a large-scale radwaste isolation natural analogue study

    SciTech Connect

    Shea, M.

    1995-09-01

    The proper isolation of radioactive waste is one of today`s most pressing environmental issues. Research is being carried out by many countries around the world in order to answer critical and perplexing questions regarding the safe disposal of radioactive waste. Natural analogue studies are an increasingly important facet of this international research effort. The Pocos de Caldas Project represents a major effort of the international technical and scientific community towards addressing one of modern civilization`s most critical environmental issues - radioactive waste isolation.

  1. Synthesis and Anti-Tuberculosis Activity of the Marine Natural Product Caulerpin and Its Analogues

    PubMed Central

    Canché Chay, Cristina I.; Gómez Cansino, Rocío; Espitia Pinzón, Clara I.; Torres-Ochoa, Rubén O.; Martínez, Roberto

    2014-01-01

    Caulerpin (1a), a bis-indole alkaloid from the marine algal Caulerpa sp., was synthesized in three reaction steps with an overall yield of 11%. The caulerpin analogues (1b–1g) were prepared using the same synthetic pathway with overall yields between 3% and 8%. The key reaction involved a radical oxidative aromatic substitution involving xanthate (3) and 3-formylindole compounds (4a–4g). All bis-indole compounds synthesized were evaluated against the Mycobacterium tuberculosis strain H37Rv, and 1a was found to display excellent activity (IC50 0.24 µM). PMID:24681629

  2. A natural analogue of high-pH cement pore waters from the Maqarin area of northern Jordan: Comparison of predicted and observed trace-element chemistry of uranium and selenium

    NASA Astrophysics Data System (ADS)

    Linklater, C. M.; Albinsson, Y.; Alexander, W. R.; Casas, I.; McKinley, I. G.; Sellin, P.

    1996-02-01

    Current design concepts for low-/intermediate-level radioactive waste disposal in many countries involve emplacement underground in a cementitious repository. The highly alkaline groundwaters at Maqarin, Jordan, are a good analogue for the cementitious pore waters that will be present within such a repository. A geochemical modelling study of these groundwaters has been carried out in order to test the applicability of equilibrium models in geochemical programs and their associated thermodynamic databases in such hyperalkaline conditions. This was achieved by comparison of elemental solubilities and speciations predicted by the programs with observations in the natural system. Five organisations took part in the study: AEA Technology, U.K.; Chalmers University of Technology, Sweden; MBT Tecnología Ambiental, Spain; Nagra, Switzerland; and SKB, Sweden. The modelling study was coordinated by the University of Berne. The results of the study showed good agreement between the predictions of the programs employed. Comparison of the observed solids with those predicted by the models has allowed limited validation of the databases. The results for U and Se are presented here.

  3. Geochemical processes controlling water salinization in an irrigated basin in Spain: identification of natural and anthropogenic influence.

    PubMed

    Merchán, D; Auqué, L F; Acero, P; Gimeno, M J; Causapé, J

    2015-01-01

    Salinization of water bodies represents a significant risk in water systems. The salinization of waters in a small irrigated hydrological basin is studied herein through an integrated hydrogeochemical study including multivariate statistical analyses and geochemical modeling. The study zone has two well differentiated geologic materials: (i) Quaternary sediments of low salinity and high permeability and (ii) Tertiary sediments of high salinity and very low permeability. In this work, soil samples were collected and leaching experiments conducted on them in the laboratory. In addition, water samples were collected from precipitation, irrigation, groundwater, spring and surface waters. The waters show an increase in salinity from precipitation and irrigation water to ground- and, finally, surface water. The enrichment in salinity is related to the dissolution of soluble mineral present mainly in the Tertiary materials. Cation exchange, precipitation of calcite and, probably, incongruent dissolution of dolomite, have been inferred from the hydrochemical data set. Multivariate statistical analysis provided information about the structure of the data, differentiating the group of surface waters from the groundwaters and the salinization from the nitrate pollution processes. The available information was included in geochemical models in which hypothesis of consistency and thermodynamic feasibility were checked. The assessment of the collected information pointed to a natural control on salinization processes in the Lerma Basin with minimal influence of anthropogenic factors. PMID:25262295

  4. Geochemical processes controlling water salinization in an irrigated basin in Spain: identification of natural and anthropogenic influence.

    PubMed

    Merchán, D; Auqué, L F; Acero, P; Gimeno, M J; Causapé, J

    2015-01-01

    Salinization of water bodies represents a significant risk in water systems. The salinization of waters in a small irrigated hydrological basin is studied herein through an integrated hydrogeochemical study including multivariate statistical analyses and geochemical modeling. The study zone has two well differentiated geologic materials: (i) Quaternary sediments of low salinity and high permeability and (ii) Tertiary sediments of high salinity and very low permeability. In this work, soil samples were collected and leaching experiments conducted on them in the laboratory. In addition, water samples were collected from precipitation, irrigation, groundwater, spring and surface waters. The waters show an increase in salinity from precipitation and irrigation water to ground- and, finally, surface water. The enrichment in salinity is related to the dissolution of soluble mineral present mainly in the Tertiary materials. Cation exchange, precipitation of calcite and, probably, incongruent dissolution of dolomite, have been inferred from the hydrochemical data set. Multivariate statistical analysis provided information about the structure of the data, differentiating the group of surface waters from the groundwaters and the salinization from the nitrate pollution processes. The available information was included in geochemical models in which hypothesis of consistency and thermodynamic feasibility were checked. The assessment of the collected information pointed to a natural control on salinization processes in the Lerma Basin with minimal influence of anthropogenic factors.

  5. A natural analogue for high-level waste in tuff: Chemical analysis and modeling of the Valles site

    SciTech Connect

    Stockman, H.W.; Krumhansl, J.L.; Ho, C.K.; Kovach, L.; McConnell, V.S.

    1995-03-01

    The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a high-level waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock Tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, x-ray diffraction, and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and {sup 39}Ar/{sup 40}Ar isotopic composition. Overall, the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 m of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks.

  6. A Natural Analogue for Thermal-Hydrological-Chemical Coupled Processes at the Proposed Nuclear Waste Repository at Yucca Mountain, Nevada

    SciTech Connect

    Bill Carey; Gordon Keating; Peter C. Lichtner

    1999-08-01

    Dike and sill complexes that intruded tuffaceous host rocks above the water table are suggested as natural analogues for thermal-hydrologic-chemical (THC) processes at the proposed nuclear waste repository at Yucca Mountain, Nevada. Scoping thermal-hydrologic calculations of temperature and saturation profiles surrounding a 30-50 m wide intrusion suggest that boiling conditions could be sustained at distances of tens of meters from the intrusion for several thousand years. This time scale for persistence of boiling is similar to that expected for the Yucca Mountain repository with moderate heat loading. By studying the hydrothermal alteration of the tuff host rocks surrounding the intrusions, insight and relevant data can be obtained that apply directly to the Yucca Mountain repository and can shed light on the extent and type of alteration that should be expected. Such data are needed to bound and constrain model parameters used in THC simulations of the effect of heat produced by the waste on the host rock and to provide a firm foundation for assessing overall repository performance. One example of a possible natural analogue for the repository is the Paiute Ridge intrusive complex located on the northeastern boundary of the Nevada Test Site, Nye County, Nevada. The complex consists of dikes and sills intruded into a partially saturated tuffaceous host rock that has stratigraphic sequences that correlate with those found at Yucca Mountain. The intrusions were emplaced at a depth of several hundred meters below the surface, similar to the depth of the proposed repository. The tuffaceous host rock surrounding the intrusions is hydrothermally altered to varying extents depending on the distance from the intrusions. The Paiute Ridge intrusive complex thus appears to be an ideal natural analogue of THC coupled processes associated with the Yucca Mountain repository. It could provide much needed physical and chemical data for understanding the influence of heat

  7. Estimation of Fe3+/Fetot. ratio in natural silicate glasses and analogues for extra-terrestrial basalt using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Di Genova, D.; Hess, K. U.; Chevrel, M. O.; Dingwell, D. B.

    2015-12-01

    The effect of iron oxidation state (Fe3+/Fetot.) on the Raman spectra of pantelleritic (from Pantelleria island) and basaltic glasses (from Etna) and synthetic analogues for extra-terrestrial basaltic glasses (iron-rich martian basalt analogues; Chevrel et al. 2014) has been investigated. The Raman spectra of pantellerite glasses show dramatic changes in the high wavelength region of the spectrum (800-1200cm-1) as iron oxidation state changes. In particular the 970 cm-1 band intensity increases with increasing oxidation state of the glass (Fe3+/Fetot. ratio from 0.24 to 0.83). In contrast, Raman spectra of the basaltic glasses (natural and synthetic) do not show the same oxidation state sensitivity as the pantelleritic samples (Fe3+/Fetot. ratio from 0.15 to 0.79). A shift, however, of the 950 cm-1 band to high wavenumber with decreasing iron oxidation state can be observed. To help develop Raman spectroscopy as a quantitative tool in both geosciences and planetary science we present here an empirical, compositionally-independent model, based on an ideal mixing equation applied to the acquired Raman spectra. This model yields estimates of the iron oxidation state of anhydrous and hydrous silicate glasses of basaltic and pantelleritic composition for Fe3+/Fetot. ranging between 0.15 and 0.83 and water contents up to 2.4 wt.%. The model has been validated using independently characterized natural and synthetic silicate glasses (both anhydrous and hydrous) with a FeO content varying from ~8 to ~22 wt%. The results of this study contribute to increase the compositionally-dependent database previously presented by Di Genova et al. (2015) for Raman spectra of complex silicate glasses. The applications of this model range from microanalysis of silicate glasses (e.g. melt inclusions) to handheld in situ terrestrial field studies and under extreme conditions (e.g. extraterrestrial, volcanic and submarine environments).

  8. An interregional analysis of natural vegetation analogues using ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Poulton, C. E.; Welch, R. I.

    1973-01-01

    The identification of ecological analogs of natural vegetation and food crops using ERTS-1 imagery is discussed. Signatures of four natural vegetation analogs have been determined from color photography. Color additive techniques to improve the photointerpretation are examined. Tests were conducted at test sites in Louisiana, California, and Colorado.

  9. Geochemical Signature of Natural Water Recharge in the Jungar Basin and Its Response to Climate.

    PubMed

    Zhu, Bingqi; Yu, Jingjie; Rioual, Patrick

    2016-01-01

    This paper analyzed the physico-chemical characteristics of natural waters in a drainage system of the Jungar Basin, northwestern China to identify chemical evolution and recharge mechanisms of natural waters in an arid environment. The waters studied are different in mineralization, but are typically carbonate rivers and alkaline in nature. No Cl-dominated water type occurs, indicating an early stage of water evolution. Regolith and geomorphological parameters controlling ground-surface temperature may play a large role in the geological evolution of the water. Three main morphological and hydrological units are reflected in water physico-chemistry. Climate influences the salinization of natural waters substantially. Direct recharge from seasonal snow and ice-melt water and infiltration of rain to the ground are significant recharge processes for natural waters, but recharge from potential deep groundwater may be less important. The enrichment of ions in lakes has been mainly caused by evaporation rather than through the quality change of the recharged water.

  10. Characterization of U-series disequilibria at the Pena Blanca natural analogue site, Chihuahua, Mexico

    SciTech Connect

    Wong, V.; Goodell, P.C.; Anthony, E.Y.

    1999-07-01

    The purpose of this study was to evaluate radionuclide migration from a uranium-mineralized breccia pipe. The site provides an excellent opportunity to evaluate radionuclide mobility in a geochemical environment similar to that around the proposed high-level waste repository at Yucca Mountain, Nevada. Samples represent fracture-infillings from both within and outside the breccia pipe. Mineral assemblages within the fractures include (1) pure kaolinite, (2) a mixture of iron-oxyhydroxides (goethite and hematite) with associated alunite and jarosite, which the authors refer to as the Fe-mineral assemblage, and (3) carbonates. Uranophane, weeksite, soddyite, and boltwoodite are associated with samples from within the breccia zone. The authors obtain radionuclide activities from gamma-ray rather than alpha spectroscopy, and the methodology for these measurements is presented in detail. Plots of {sup 230}Th/{sup 238}U vs. {sup 226}Ra/{sup 230}Th show three distinct mobility trends. (1) The majority of the Fe-mineral samples from within the breccia pipe yield values between 1.0 and 1.1 for both ratios, (2) Fe-mineral samples from outside the ore zone and a kaolinite from within the ore zone have {sup 230}Th/{sup 238}U of 0.58 to 0.83 and {sup 226}Ra/{sup 230}Th of 1.09 to 1.42, and (3) some Fe-mineral samples from within the breccia pipe have values of 1.2 and 0.9 respectively. These data, combined with those from other studies at Pena Blanca suggest that U and Ra are sometimes mobile in the near-surface environment and that multiple episodes of enrichment and leaching are required to explain the trends.

  11. Putting the Fizz in the Fissure: Geochemical and Geomechanical Effects of Carbonated Brine in a Natural Fracture

    NASA Astrophysics Data System (ADS)

    Smith, M. M.; Walsh, S. D.; Carroll, S.

    2012-12-01

    The increased mobility and buoyancy of CO2, coupled with rising demands for renewable energy production, make it an attractive alternative heat-exchange fluid in lieu of water for use in enhanced geothermal systems (EGS). However, the geochemical impact of elevated CO2 levels on these engineered systems and the consequent effects on reservoir capacity and system permeability are poorly-constrained at present, leading to uncertainty in predictions of longer-term reservoir performance. For example, consistently high levels of aqueous CO2 cycling through the subsurface may result in relatively rapid and extensive dissolution of pH-sensitive minerals, with an increased risk of secondary alteration phase precipitation (e.g., oxides, clays, and/or carbonate minerals) and adverse effects on EGS resource productivity. If, however, injected CO2-rich fluids traverse the system primarily through fracture networks, other factors such as accessibly reactive surface areas, fracture asperity susceptibility, and fracture surface/wallrock exchange may also factor into the ultimate evolution of reservoir permeability. To evaluate the comparative impacts of both geochemistry and geomechanics in sustaining fracture network flow under conditions relevant to CO2-EGS, a 60-day core-flooding experiment was conducted on a naturally fractured and chemically complex greywacke core sample exposed to CO2-acidified brine at 200C and 25MPa. The objective of this study was to investigate the potential effects of using CO2 as a heat-exchange fluid on fracture flow and reaction within a pre-existing well-characterized fracture representative of reactivated fractures targeted for stimulation in many EGS projects. Over the course of the experiment, changes in solution chemistry and pressure/permeability were monitored. In addition, pre- and post-reaction three-dimensional high-resolution X-ray computed tomography (XRCT) imaging was used to determine changes in fracture aperture and geometry as well

  12. Informatic search strategies to discover analogues and variants of natural product archetypes.

    PubMed

    Johnston, Chad W; Connaty, Alex D; Skinnider, Michael A; Li, Yong; Grunwald, Alyssa; Wyatt, Morgan A; Kerr, Russell G; Magarvey, Nathan A

    2016-03-01

    Natural products are a crucial source of antimicrobial agents, but reliance on low-resolution bioactivity-guided approaches has led to diminishing interest in discovery programmes. Here, we demonstrate that two in-house automated informatic platforms can be used to target classes of biologically active natural products, specifically, peptaibols. We demonstrate that mass spectrometry-based informatic approaches can be used to detect natural products with high sensitivity, identifying desired agents present in complex microbial extracts. Using our specialised software packages, we could elaborate specific branches of chemical space, uncovering new variants of trichopolyn and demonstrating a way forward in mining natural products as a valuable source of potential pharmaceutical agents. PMID:26350080

  13. The geochemical nature of the Archean Ancient Gneiss Complex and Granodiorite Suite, Swaziland: a preliminary study

    USGS Publications Warehouse

    Hunter, D.R.; Barker, F.; Millard, H.T., Jr.

    1978-01-01

    The Ancient Gneiss Complex (AGC) of Swaziland, an Archean gray gneiss complex, lies southeast and south of the Barberton greenstone belt and includes the most structurally complex and highly metamorphosed portions of the eastern Kaapvaal craton. The AGC is not precisely dated but apparently is older than 3.4 Ga. The AGC consists of three major units: (a) a bimodal suite of closely interlayered siliceous, low-K gneisses and metabasalt; (b) homogeneous tonalite gneiss; and (c) interlayered siliceous microcline gneiss, metabasalt, and minor metasedimentary rocks - termed the metamorphite suite. A geologically younger gabbro-diorite-tonalite-trondhjemite suite, the Granodiorite Suite, is spatially associated with the AGC and intrusive into it. The bimodal suite consists largely of two types of low-K siliceous gneiss: one has SiO2 14%, low Rb/Sr ratios, and depleted heavy rare earth elements (REE's); the other has SiO2 > 75%, Al2O3 < 13%, high Rb/Sr ratios, and relatively abundant REE's except for negative Eu anomalies. The interlayered metabasalt ranges from komatiitic to tholeiitic compositions. Lenses of quartz monzonitic gneiss of K2O/Na2O close to 1 form a minor part of the bimodal suite. Tonalitic to trondhjemitic migmatite locally is abundant and has major-element abundances similar to those of non-migmatitic varieties. The siliceous gneisses of the metamorphic suite show low Al2O, K2O/Na2O ratios of about 1, high Rb/Sr ratios, moderate REE abundances and negative Eu anomalies. K/Rb ratios of siliceous gneisses of the bimodal suite are very low (???130); of the tonalitic gneiss, low (???225); of the siliceous gneiss of the metamorphite suite, moderate (???300); and of the Granodiorite Suite, high (???400). Rocks of the AGC differ geochemically in several ways from the siliceous volcanic and hypabyssal rocks of the Upper Onverwacht Group and from the diapirs of tonalite and trondhjemite that intrude the Swaziland Group. ?? 1978.

  14. Geochemical Signature of Natural Water Recharge in the Jungar Basin and Its Response to Climate.

    PubMed

    Zhu, Bingqi; Yu, Jingjie; Rioual, Patrick

    2016-01-01

    This paper analyzed the physico-chemical characteristics of natural waters in a drainage system of the Jungar Basin, northwestern China to identify chemical evolution and recharge mechanisms of natural waters in an arid environment. The waters studied are different in mineralization, but are typically carbonate rivers and alkaline in nature. No Cl-dominated water type occurs, indicating an early stage of water evolution. Regolith and geomorphological parameters controlling ground-surface temperature may play a large role in the geological evolution of the water. Three main morphological and hydrological units are reflected in water physico-chemistry. Climate influences the salinization of natural waters substantially. Direct recharge from seasonal snow and ice-melt water and infiltration of rain to the ground are significant recharge processes for natural waters, but recharge from potential deep groundwater may be less important. The enrichment of ions in lakes has been mainly caused by evaporation rather than through the quality change of the recharged water. PMID:26803030

  15. Obsidians and tektites: Natural analogues for water diffusion in nuclear waste glasses

    SciTech Connect

    Mazer, J.J.; Bates, J.K.; Bradley, C.R.; Stevenson, C.M.

    1991-11-01

    Projected scenarios for the proposed Yucca Mountain repository include significant periods of time when high relative humidity atmospheres will be present, thus the reaction processes of interest will include those known to occur under these conditions. The ideal natural analog for the proposed Yucca Mountain repository would consist of natural borosilicate glasses exposed to expected repository conditions for thousands of years; however, the prospects for identifying such an analog are remote, but an important caveat for using natural analog studies is to relate the reaction processes in the analog to those in the system of interest, rather than a strict comparison of the glass compositions. In lieu of this, identifying natural glasses that have reacted via reaction processes expected in the repository is the most attractive option. The goal of this study is to quantify molecular water diffusion in the natural analogs obsidian and tektites. Results from this study can be used in assessing the importance of factors affecting molecular water diffusion in nuclear waste glasses, relative to other identified reaction processes. In this way, a better understanding of the long-term reaction mechanism can be developed and incorporated into performance assessment models. 17 refs., 4 figs.

  16. The Antei uranium deposit: A natural analogue of an SNF repository and an underground geodynamic laboratory in granite

    NASA Astrophysics Data System (ADS)

    Laverov, N. P.; Petrov, V. A.; Poluektov, V. V.; Nasimov, R. M.; Hammer, J.; Burmistrov, A. A.; Shchukin, S. I.

    2008-10-01

    The estimation of the long-term stability of crystalline rock massifs with respect to natural and technogenic loads in the course of long-term storage of spent nuclear fuel (SNF) is a special area of surveys at underground research laboratories (URLs). In parallel with these surveys, data on uranium deposits—natural analogues of repositories of SNF consisting of 95% UO2—are used for obtaining insight into the dynamics of radionuclide migration and validating barrier properties of host rocks. Examples of URLs located in granitic massifs of Sweden (Äspö), Canada (Whiteshell), Switzerland (Grimsel), Japan (Mizunami), and Finland (ONKALO), as well as the El Berrocal (Spain), Palmottu (Finland), Sanerliu (China), and Kamaishi (Japan) deposits, are considered in the paper. The objects listed above are distinct in tectonic settings, geology, control of ore mineralization, redox conditions of uranium migration, and character and intensity of filtration and transportation, which predetermine the direction and specific features of research conducted therein. A variant in which a URL and a natural analogue are combined in one object is especially promising for validation of safe long-term isolation of SNF. The Antei vein-stockwork uranium deposit in the southeastern Transbaikal region, localized in Paleozoic granite at a depth of 400 1000 m and opened by mine workings at six levels, is such an object. Its geological features, stress-strain state, and infrastructure of mine workings offer an opportunity to study the entire spectrum of processes proceeding in near-and far-field of an SNF repository. The structural geology, mineralogy and petrography, and petrophysical and tectonophysical features of the deposit at its three lower levels are considered. The sequence of metasomatic alteration of rocks and the dynamics of formation of ore-bearing faults that crosscut prototectonic elements, as well as relationships of physicomechanical properties of rocks as a function of

  17. Multicomponent reactive transport in discrete fractures. II: Infiltration of hyperalkaline groundwater at Maqarin, Jordan, a natural analogue site

    NASA Astrophysics Data System (ADS)

    Steefel, C. I.; Lichtner, P. C.

    1998-08-01

    A numerical multicomponent reactive transport model described fully in Steefel and Lichtner (1998)[Steefel, C.I., Lichtner, P.C., 1998. Multicomponent reactive transport in discrete fractures, I. Controls on reaction front geometry. J. Hydrol. (in press)] is used to simulate the infiltration of hyperalkaline groundwater along discrete fractures at Maqarin, Jordan, a site considered as a natural analogue to cement-bearing nuclear waste repositories. In the Eastern Springs area at Maqarin, two prominent sets of sub-parallel fractures trending NW-SE are approximately perpendicular to the local water table contours, with the slope of the water table indicating north-westward flow. Extensive mineralogic investigations [Alexander W.R. (Ed.), 1992. A natural analogue study of cement-buffered, hyperalkaline groundwaters and their interaction with a sedimentary host rock. NAgrA Technical Report (NTB 91-10), Wettingen, Switzerland; Milodowski, A.E., Hyslop, E.K., Pearce, J.M., Wetton, P.D., Kemp, S.J., Longworth, G., Hodginson, E., and Hughes, C.R., 1998. Mineralogy and geochemistry of the western springs area. In: Smellie, J.A.T. (ed.), 1998: Maqarin Natural Analogue Study: Phase III. SKB Technical Report TR98-04, Stockholm, Sweden] indicate that the width of intense rock alteration zone bordering the fractures changes from about 4 mm at one locality (the M1 sampling site) to approximately 1 mm 100 m to the north-west in the flow direction (the M2 site), suggesting a lessening of alteration intensity in that direction. Using this information, the dimensionless parameter δ v/φ D' (φ=porosity, D'=effective diffusion coefficient in rock matrix, δ=fracture aperture, and v=fluid velocity in the fracture) and measurements of the local hydraulic head gradient and effective diffusion coefficient in the rock matrix, a mean fracture aperture of 0.194 mm is calculated assuming the cubic law applies. This information, in combination with measured groundwater compositions at the

  18. Magnesium isotope fractionation by chemical diffusion in natural settings and in laboratory analogues

    NASA Astrophysics Data System (ADS)

    Chopra, Rahul; Richter, Frank M.; Bruce Watson, E.; Scullard, Christian R.

    2012-07-01

    Laboratory experiments are used to document isotopic fractionation of magnesium by chemical diffusion in a silicate melt and the results compared to the magnesium isotopic composition across contacts between igneous rocks of different composition in natural settings. The natural samples are from transects from felsic to mafic rocks at Vinal Cove in the Vinalhaven Intrusive Complex, Maine and from the Aztec Wash pluton in Nevada. Two laboratory diffusion couples made by juxtaposing melts made from powders of the felsic and mafic compositions sampled at Vinal Cove were annealed at about 1500 °C for 22.5 and 10 h, respectively. The transport of magnesium in the diffusion couples resulted in easily measured magnesium isotopic fractionations at the interface (δ26Mg∼1.5‰). These isotopic fractionations provide a distinctive isotopic “fingerprint” that we use to determine whether chemical gradients in natural settings where melts of different composition were juxtaposed were due to chemical diffusion. The magnesium isotopic fractionation along one profile at Vinal Cove is exactly what one would expect based on the fractionations found in the laboratory experiments. This is an important result in that it shows that the isotope fractionation by chemical diffusion found in highly controlled laboratory experiments can be found in a natural setting. This correspondence implies that chemical diffusion was the dominant process responsible for the transport of magnesium across this particular contact at Vinal Cove. A second Vinal Cove profile has a very similar gradient in magnesium concentration but with significantly less magnesium isotopic fractionation than expected. This suggests that mass transport at this location was only partly by diffusion and that some other mass transport mechanism such as mechanical mixing must have also played a role. The magnesium isotopic composition of samples from Aztec Wash shows no resolvable isotopic fractionation across the contact

  19. Natural glass analogues to alteration of nuclear waste glass: A review and recommendations for further study

    SciTech Connect

    McKenzie, W.F.

    1990-01-01

    The purpose of this report is to review previous work on the weathering of natural glasses; and to make recommendations for further work with respect to studying the alteration of natural glasses as it relates quantifying rates of dissolution. the first task was greatly simplified by the published papers of Jercinovic and Ewing (1987) and Byers, Jercinovic, and Ewing (1987). The second task is obviously the more difficult of the two and the author makes no claim of completeness in this regard. Glasses weather in the natural environment by reacting with aqueous solutions producing a rind of secondary solid phases. It had been proposed by some workers that the thickness of this rind is a function of the age of the glass and thus could be used to estimate glass dissolution rates. However, Jercinovic and Ewing (1987) point out that in general the rind thickness does not correlate with the age of the glass owing to the differences in time of contact with the solution compared to the actual age of the sample. It should be noted that the rate of glass dissolution is also a function of the composition of both the glass and the solution, and the temperature. Quantification of the effects of these parameters (as well as time of contact with the aqueous phase and flow rates) would thus permit a prediction of the consequences of glass-fluid interactions under varying environmental conditions. Defense high- level nuclear waste (DHLW), consisting primarily of liquid and sludge, will be encapsulated by and dispersed in a borosilicate glass before permanent storage in a HLW repository. This glass containing the DHLW serves to dilute the radionuclides and to retard their dispersion into the environment. 318 refs.

  20. Novel peptide chemistry in terrestrial animals: natural luciferin analogues from the bioluminescent earthworm Fridericia heliota.

    PubMed

    Dubinnyi, Maxim A; Tsarkova, Aleksandra S; Petushkov, Valentin N; Kaskova, Zinaida M; Rodionova, Natalja S; Kovalchuk, Sergey I; Ziganshin, Rustam H; Baranov, Mikhail S; Mineev, Konstantin S; Yampolsky, Ilia V

    2015-03-01

    We report isolation and structure elucidation of AsLn5, AsLn7, AsLn11 and AsLn12: novel luciferin analogs from the bioluminescent earthworm Fridericia heliota. They were found to be highly unusual modified peptides, comprising either of the two tyrosine-derived chromophores, CompX or CompY and a set of amino acids, including threonine, gamma-aminobutyric acid, homoarginine, and unsymmetrical N,N-dimethylarginine. These natural compounds represent a unique peptide chemistry found in terrestrial animals and rise novel questions concerning their biosynthetic origin.

  1. New time-resolved micro-photoluminescence spectroscopy of natural and synthetic analogue minerals

    NASA Astrophysics Data System (ADS)

    Panczer, G.; Ollier, N.; Champagnon, B.; Gaft, M.

    2003-04-01

    Minerals as well as geomaterials often present light emissions under UV or visible excitations. This property called photoluminescence is due to low concentration impurities such as the rare earths, the transition elements and the lanthanides. The induced color is used for ore prospection but only spectroscopic analyses indicate the nature of the emitted centers. However natural samples contained numerous luminescent centers simultaneously and with regular steady-state measurements (such as in cathodoluminescence) all the emissions are often over lapping. In order to record the contributions of each separate center, it is possible to use time-resolved measurements based on the decay time of the emissions and using pulsed laser excitation. Some characteristic examples will be presented on apatites, zircons as well as gemstones. Geomaterials present as well micro scale heterogeneities (growth zoning, inclusions, devitrification, microphases...). Precise identification and optical effects of such heterogeneities have to be taken into account. To reach the microscale using photo luminescence studies, a microscope has be modified to allowed pulsed laser injection (from UV to visible), beam focus with micro scale resolution on the sample (<10 μm), as well as time resolved collection of micro fluorescence. Such equipment allows now undertaking time-resolved measurements of microphases. Applications on geomaterials will be presented.

  2. Naturally occurring arsenic in groundwater and identification of the geochemical sources in the Duero Cenozoic Basin, Spain

    NASA Astrophysics Data System (ADS)

    Gómez, J. J.; Lillo, J.; Sahún, B.

    2006-09-01

    Arsenic concentrations surpassing potability limit of 10 μg/L in the groundwater supplies of an extensive area in the Duero Cenozoic Basin (central Spain) have been detected and the main sources of arsenic identified. Arsenic in 514 samples of groundwater, having mean values of 40.8 μg/L, is natural in origin. Geochemical analysis of 553 rock samples, assaying arsenic mean values of 23 mg/kg, was performed. Spatial coincidence between the arsenic anomaly in groundwater and the arsenic lithogeochemical distribution recorded in the Middle Miocene clayey organic-rich Zaratan facies illustrates that the rocks of this unit are the main source of arsenic in groundwater. The ferricretes associated to the Late Cretaceous-Middle Miocene siliciclastics also constitute a potential arsenic source. Mineralogical study has identified the presence of arsenic in iron oxides, authigenic pyrite, manganese oxides, inherited titanium-iron oxides, phyllosilicates and organomineral compounds. Arsenic mobilization to groundwater corresponds to arsenic desorption from iron and manganese oxides and from organic matter.

  3. The geochemical behavior of natural radionuclides in coastal waters: A modeling study for the Huelva estuary

    NASA Astrophysics Data System (ADS)

    Periáñez, Raúl; Hierro, Almudena; Bolívar, Juan Pedro; Vaca, Federico

    2013-10-01

    A numerical model to study the behavior and distribution of natural radionuclides in sediments of an estuary (Odiel and Tinto rivers, SW Spain) affected by acid mine drainage and industrial activities has been developed. The model solves water circulation due to tides and river stream flows. The dispersion model includes uptake/release reactions of radionuclides between the dissolved phase and bed sediments in a dynamic way, using kinetic transfer coefficients. Seasonal pH and chlorinity distributions are simulated, and a formulation has been developed to consider these seasonal variations on kinetic coefficients. Calculated concentrations of 226Ra and 238U in sediments have been compared with measurements from four seasonal sampling campaigns. Numerical experiments have been carried out to study the relative significance of the different radionuclides sources into the estuary as well as the effect of the two components of water circulation (tides are river flows) on radionuclide dispersion patterns.

  4. Improving and testing geochemical speciation predictions of metal ions in natural waters.

    PubMed

    Ahmed, Imad A M; Hamilton-Taylor, John; Bieroza, Magdalena; Zhang, Hao; Davison, William

    2014-12-15

    The ability of WHAM VII and NICA-Donnan models to predict free-ion activities of Cu in natural waters was examined from two perspectives, (i) the presence of EDTA and NTA contaminants, (ii) the need to improve estimates of HA and FA concentrations. Potentiometric responses of a Cu(II) ion-selective electrode were investigated in five assays containing dissolved organic matter (DOM) isolated from a series of polluted (urban) and relatively unpolluted (upland) streams in northern England. The [Cu]/[DOC] ratio in these assays spanned an environmentally realistic range of ∼1-500 μmol/g. Reasonably good agreement between measured and predicted Cu(2+) activities was obtained with both WHAM VII and NICA-Donnan models, assuming 65% of DOM as fulvic acid and including the measured EDTA and NTA concentrations, but generally the models overestimated the activities by a factor of ∼2. In contrast, the models over-predicted the Cu(2+) activities by up to 2 orders of magnitude at low [Cu]/[DOC] ratios in urban waters if anthropogenic ligands were not included in the model simulations. Three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy was used to measure the functional properties of the isolated DOM and to estimate the fractions of FA and HA present. Using these fractions in the models gave improvements in predictions compared to the 65% FA assumption, as shown by higher correlations, reduced error and reduced bias. These results highlight various issues with the use of the available speciation models for predicting free ion concentrations in natural waters, such as the use of the Biotic Ligand Model (BLM) for the derivation of environmental standards. It is clearly necessary to measure EDTA and NTA in waters with urban influences, while fluorescence measurements offer the possibility of appreciably improving the accuracy of predictions.

  5. Insights into the nature of cometary organic matter from terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Court, Richard W.; Sephton, Mark A.

    2012-04-01

    The nature of cometary organic matter is of great interest to investigations involving the formation and distribution of organic matter relevant to the origin of life. We have used pyrolysis-Fourier transform infrared (FTIR) spectroscopy to investigate the chemical effects of the irradiation of naturally occurring bitumens, and to relate their products of pyrolysis to their parent assemblages. The information acquired has then been applied to the complex organic matter present in cometary nuclei and comae. Amalgamating the FTIR data presented here with data from published studies enables the inference of other comprehensive trends within hydrocarbon mixtures as they are progressively irradiated in a cometary environment, namely the polymerization of lower molecular weight compounds; an increased abundance of polycyclic aromatic hydrocarbon structures; enrichment in 13C; reduction in atomic H/C ratio; elevation of atomic O/C ratio and increase in the temperature required for thermal degradation. The dark carbonaceous surface of a cometary nucleus will display extreme levels of these features, relative to the nucleus interior, while material in the coma will reflect the degree of irradiation experienced by its source location in the nucleus. Cometary comae with high methane/water ratios indicate a nucleus enriched in methane, favouring the formation of complex organic matter via radiation-induced polymerization of simple precursors. In contrast, production of complex organic matter is hindered in a nucleus possessing a low methane/water ration, with the complex organic matter that does form possessing more oxygen-containing species, such as alcohol, carbonyl and carboxylic acid functional groups, resulting from reactions with hydroxyl radicals formed by the radiolysis of the more abundant water. These insights into the properties of complex cometary organic matter should be of particular interest to both remote observation and space missions involving in situ

  6. Natural glass from Deccan volcanic province: an analogue for radioactive waste form

    NASA Astrophysics Data System (ADS)

    Rani, Nishi; Shrivastava, J. P.; Bajpai, R. K.

    2015-11-01

    Deccan basaltic glass is associated with the differentiation centres of the vast basaltic magmas erupted in a short time span. Its suitability as a radioactive waste containment chiefly depends on alteration behaviour; however, detailed work is needed on this glass. Therefore, the basaltic glass was treated under hydrothermal-like conditions and then studied to understand its alteration. Moreover, comparison of these results with the naturally altered glass is also documented in this paper. Solutions as well as residue obtained after glass alteration experiments were analysed. Treated glass specimens show partial to complete release of all the ions during alteration; however, abundant release of Si and Na ions is noticed in case of almost all the specimens and the ionic release is of the order of Na > Si > K > Ca > Al = Mg > Fe > Mn > Ti. Scanning electron images of the altered residue show morphologies of smectite, montmorillonite and illite inside as well as outside of the secondary layers, and represent paragenesis of alteration minerals. It has been noticed that the octahedral cation occupancies of smectite are consistent with the dioctahedral smectite. The secondary layer composition indicates retention for Si, Al, and Mg ions, indicating their fixation in the alteration products, but remarkably high retention of Ti, Mn and Fe ions suggests release of very small amount of these elements into the solution. By evolution of the secondary layer and retention of less soluble ions, the obstructive effect of the secondary layer increases and the initial constant release rate begins slowly to diminish with the proceeding time. It has been found that devitrification of glass along the cracks, formation of spherulite-like structures and formation of yellowish brown palagonite, chlorite, calcite, zeolite and finally white coloured clays yielded after experiments that largely correspond to altered obsidian that existed in the natural environment since inception ~66 Ma ago.

  7. Geochemical Evidence for Possible Natural Migration of Marcellus Formation Brine to Shallow Aquifers in Pennsylvania

    NASA Astrophysics Data System (ADS)

    Warner, N. R.; Darrah, T. H.; Jackson, R. B.; Osborn, S.; Down, A.; Vengosh, A.

    2012-12-01

    The acceleration in production of natural gas from shale formations through horizontal drilling and hydraulic fracturing has altered the landscape of domestic energy production in the USA. Yet shale gas exploration has generated an increased awareness of risks to drinking water quality amid concerns for the possible migration of stray gas or hydraulic fracturing fluid and/or flowback brine to shallow drinking water aquifers. The degree to which shallow drinking water is at risk from hydraulic fracturing could depend upon the hydraulic connectivity between the shale gas formations and the surface. In this study, we analyzed the geochemistry of over 400 water samples located across six counties of northeastern Pennsylvania in the three principle aquifers, two Upper Devonian Age bedrock aquifers (Catskill and Lock Haven) and one Quaternary Age (Alluvium) that overlie the Marcellus Formation. Based on a detailed analysis of major (Br, Cl, Na, Mg, Ba, and Sr) and trace (Li) element geochemistry, coupled with utilization of a specific spectrum of isotopic tracers (87Sr/86Sr, 228Ra/ 226Ra, 2H/H, 18O/16O), we identify a salinized (Cl> 20 mg/L) shallow groundwater type which suggests conservative mixing relationships between fresh shallow groundwater and an underlying brine. Identification of the brine source is complicated as many of the brines in the northern Appalachian Basin likely share a common origin as the expelled remnants of the formation of the Silurian Salina evaporate deposits. To determine the ultimate source of the diluted brine we compared the observed geochemistry to over 80 brines produced from northern Appalachian Basin formations. The shallow salinized groundwater most closely resembles diluted produced water from the Middle Devonian Marcellus Formation. The 18O/16O and 2H/H of the salinized groundwater indicate that the brine is likely diluted with post-glacial (<10,000 ybp) meteoric water. Combined, these data indicate that hydraulic connections

  8. IMPACTS OF SOLUBILITY AND OTHER GEOCHEMICAL PROCESSES ON RADIONUCLIDE RETARDATION IN THE NATURAL SYSTEM

    SciTech Connect

    B. Arnold

    2005-08-02

    This report documents results and findings of a study of solubility/co-precipitation effects and enhanced sorption due to variations in redox conditions on radionuclide transport in the natural system (BSC 2005 [DIRS 173951]; BSC 2005 [DIRS 173859]) conducted in response to DOE Contracting Officer Authorization Letter 05-001, Item d (Mitchell 2005 [DIRS 173265]). The purpose of this study is to assess the potential impacts of precipitation and enhanced sorption due to variations in redox conditions on radionuclide transport in the saturated zone (SZ) at Yucca Mountain. The information presented in this report is intended to aid in assessing the conservatism in the SZ transport model for supporting the total system performance assessment (TSPA) calculations. A similar study was performed for the impact of solubility/precipitation on radionuclide transport in the unsaturated zone (UZ). However, because the unsaturated zone is under predominantly oxidizing conditions and that the radionuclides released from the engineered barrier system are not expected to precipitate in the UZ for the reasons described below, it was concluded that the effect on unsaturated zone transport is not significant to warrant a detailed study. Solubility limiting conditions for neptunium in the UZ are expected to be similar to the conditions for neptunium solubility in the waste emplacement drift invert, where Np{sub 2}O{sub 5} is recommended as the controlling solid phase (BSC 2005 [DIRS 174566], Section 6.6.1). Solubility limits for neptunium inside the waste package, however, are expected to be controlled by NpO{sub 2} (BSC 2005 [DIRS 174566], Section 6.6.1). The solubility limits for Np2O5 are generally much higher than for NpO{sub 2} (BSC 2005 [DIRS 174566], Tables 6.6-4 and 6.6-7). Therefore, the low concentrations of neptunium releases from waste packages are unlikely to be affected by solubility limits in the unsaturated zone. The SZ is part of the Lower Natural Barrier to the

  9. Expanding dialogues: from natural autoinducers to non-natural analogues that modulate quorum sensing in Gram-negative bacteria†

    PubMed Central

    Geske, Grant D.; O’Neill, Jennifer C.; Blackwell, Helen E.

    2008-01-01

    Bacteria are capable of “communicating” their local population densities via a process termed quorum sensing (QS). Gram-negative bacteria use N-acylated l-homoserine lactones (AHLs), in conjunction with their cognate LuxR-type receptors, as their primary signalling circuit for QS. In this critical review, we examine AHL signalling in Gram-negative bacteria with a primary focus on the design of non-natural AHLs, their structure-activity relationships, and their application in chemical biological approaches to study QS. PMID:18568169

  10. Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction

    SciTech Connect

    Elizabeth C. Chapman,† Rosemary C. Capo,† Brian W. Stewart,*,† Carl S. Kirby,‡ Richard W. Hammack,§ Karl T. Schroeder,§ and Harry M. Edenborn

    2012-02-24

    Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ∼375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (εSr SW = +13.8 to +41.6, where εSr SW is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

  11. Natural flow and vertical heterogeneities in a sedimentary geothermal reservoir (Paris Basin, France): Geochemical investigations

    SciTech Connect

    Criaud, Annie, Fouassier, Philippe; Fouillac, Christian; Brach, Michel

    1988-01-01

    Three geothermal wells tapping the Dogger aquifer were studied in detail for their variations in chemical composition with time or conditions of exploitation. Analytical improvements for the determination of Cl, SO{sub 4}, Ca, Mg, Na and K make it possible to detect variations respectively of 0.15, 0.8, 0.6, 1.8, 1.8 and 1.4 %. Despite the fact that the natural flow may be important in some parts of the basin aquifer, we conclude that this factor is not responsible for the small variations noticed in mineralization within the one year survey period. The results concerning reactive and nonreactive species are best explained if a vertical heterogeneity of the chemistry of the fluid is assumed. A number of calcareous sub-layers, already demonstrated by geological studies, contribute to varying degrees to the production of the hot water. The changes in pumping rates, which are fixed according to external requirements, play a major role in the hydrodynamic and chemical disequilibrium of the wells. The consequences for the geothermal exploitations are emphasized.

  12. Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction

    SciTech Connect

    Chapman, Elizabeth C; Capo, Rosemary C.; Stewart, Brian W.; Kirby, Carl S.; Hammack, Richard W.; Schroeder, Karl T.; Edenborn, Harry M.

    2012-03-20

    Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of 375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (ε{sub Sr}{sup SW} = +13.8 to +41.6, where ε{sub Sr}{sup SW} is the deviation of the {sup 87}Sr/{sup 86}Sr ratio from that of seawater in parts per 10{sup 4}); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters.

  13. Geochemical and strontium isotope characterization of produced waters from Marcellus Shale natural gas extraction.

    PubMed

    Chapman, Elizabeth C; Capo, Rosemary C; Stewart, Brian W; Kirby, Carl S; Hammack, Richard W; Schroeder, Karl T; Edenborn, Harry M

    2012-03-20

    Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ~375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (ε(Sr)(SW) = +13.8 to +41.6, where ε(Sr) (SW) is the deviation of the (87)Sr/(86)Sr ratio from that of seawater in parts per 10(4)); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters. PMID:22360406

  14. Natural Occurring Silks and Their Analogues as Materials for Nerve Conduits

    PubMed Central

    Radtke, Christine

    2016-01-01

    Spider silk and its synthetic derivatives have a light weight in combination with good strength and elasticity. Their high cytocompatibility and low immunogenicity make them well suited for biomaterial products such as nerve conduits. Silk proteins slowly degrade enzymatically in vivo, thus allowing for an initial therapeutic effect such as in nerve scaffolding to facilitate endogenous repair processes, and then are removed. Silks are biopolymers naturally produced by many species of arthropods including spiders, caterpillars and mites. The silk fibers are secreted by the labial gland of the larvae of some orders of Holometabola (insects with pupa) or the spinnerets of spiders. The majority of studies using silks for biomedical applications use materials from silkworms or spiders, mostly of the genus Nephila clavipes. Silk is one of the most promising biomaterials with effects not only in nerve regeneration, but in a number of regenerative applications. The development of silks for human biomedical applications is of high scientific and clinical interest. Biomaterials in use for biomedical applications have to meet a number of requirements such as biocompatibility and elicitation of no more than a minor inflammatory response, biodegradability in a reasonable time and specific structural properties. Here we present the current status in the field of silk-based conduit development for nerve repair and discuss current advances with regard to potential clinical transfer of an implantable nerve conduit for enhancement of nerve regeneration. PMID:27775616

  15. Geochemical gradients in soil O-horizon samples from southern Norway: Natural or anthropogenic?

    USGS Publications Warehouse

    Reimann, C.; Englmaier, P.; Flem, B.; Gough, L.; Lamothe, P.; Nordgulen, O.; Smith, D.

    2009-01-01

    Forty soil O- and C-horizon samples were collected along a south-to-north transect extending inland for approximately 200 km from the southern tip of Norway. The elements As, Au, Bi, Cd, Cu, Ga, Ge, Hf, Hg, In, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, V, W, Zn and Zr all show a distinct decrease in concentration in soil O-horizons with increasing distance from the coast. The elements showing the strongest coastal enrichment, some by more than an order of magnitude compared to inland samples, are Au, Bi, As, Pb, Sb and Sn. Furthermore, the elements Cd (median O-/median C-horizon = 31), C, Sb, Ag, K, S, Ge (10), Hg, Pb, As, Bi, Sr (5), Se, Au, Ba, Na, Zn, P, Cu and Sn (2) are all strongly enriched in the O-horizon when compared to the underlying C-horizon. Lead isotope ratios, however, do not show any gradient with distance from the coast (declining Pb concentration). Along a 50 km topographically steep east-west transect in the centre of the survey area, far from the coast but crossing several vegetation zones, similar element enrichment patterns and concentration gradients can be observed in the O-horizon. Lead isotope ratios in the O-horizon correlate along both transects with pH and the C/N-ratio, both proxies for the quality of the organic material. Natural conditions in southern Norway, related to climate and vegetation, rather than long range atmospheric transport of air pollutants (LRT), cause the observed features. ?? 2008 Elsevier Ltd.

  16. Redox potential tuning by redox-inactive cations in nature's water oxidizing catalyst and synthetic analogues.

    PubMed

    Krewald, Vera; Neese, Frank; Pantazis, Dimitrios A

    2016-04-28

    The redox potential of synthetic oligonuclear transition metal complexes has been shown to correlate with the Lewis acidity of a redox-inactive cation connected to the redox-active transition metals of the cluster via oxo or hydroxo bridges. Such heterometallic clusters are important cofactors in many metalloenzymes, where it is speculated that the redox-inactive constituent ion of the cluster serves to optimize its redox potential for electron transfer or catalysis. A principal example is the oxygen-evolving complex in photosystem II of natural photosynthesis, a Mn4CaO5 cofactor that oxidizes water into dioxygen, protons and electrons. Calcium is critical for catalytic function, but its precise role is not yet established. In analogy to synthetic complexes it has been suggested that Ca(2+) fine-tunes the redox potential of the manganese cluster. Here we evaluate this hypothesis by computing the relative redox potentials of substituted derivatives of the oxygen-evolving complex with the cations Sr(2+), Gd(3+), Cd(2+), Zn(2+), Mg(2+), Sc(3+), Na(+) and Y(3+) for two sequential transitions of its catalytic cycle. The theoretical approach is validated with a series of experimentally well-characterized Mn3AO4 cubane complexes that are structural mimics of the enzymatic cluster. Our results reproduce perfectly the experimentally observed correlation between the redox potential and the Lewis acidities of redox-inactive cations for the synthetic complexes. However, it is conclusively demonstrated that this correlation does not hold for the oxygen evolving complex. In the enzyme the redox potential of the cluster only responds to the charge of the redox-inactive cations and remains otherwise insensitive to their precise identity, precluding redox-tuning of the metal cluster as a primary role for Ca(2+) in biological water oxidation.

  17. Geochemical variability of natural soils and reclaimed minespoil soils in the San Juan Basin, New Mexico

    USGS Publications Warehouse

    Gough, L.P.; Severson, R.C.

    1981-01-01

    An inventory of total-and extractable-element concentrations in soils was made for three areas of the San Juan Basin in New Mexico: (1) the broad area likely to be affected by energy-related development. (2) an area of soils considered to have potential for use as topsoil in mined-land reclamation. and (3) an area of the San Juan coal mine that has been regraded. topsoiled, and revegetated. Maps made of concentrations of 16 elements in area 1 soils show no gradational pattern across the region. Further. these maps do not correspond to those showing geology or soil types. Sodic or saline problems, and a possible but unproven deficiency of zinc available to plants. may make some of the soils in this area undesirable for use as topsoil in mined-land reclamation. Taxonomic great groups of soil in this area cannot be distinguished because each great group tends to have a large within-group variability if compared to the between-group variability. In area 2 the major soils sampled were of the Sheppard. Shiprock. and Doak association. These soils are quite uniform in chemical composition and are not greatly saline or sodic. As in area 1 soils. zinc deficiency may cause a problem in revegetating most of these soils. It is difficult to distinguish soil taxonomic families by using their respective chemical compositions. because of small between-family variability. Topsoil from a reclaimed area of the San Juan mine (area 3) most closely resembles the chemical composition of natural C horizons of soil from area 1. Spoil material that has not been topsoiled is likely to cause sodic-and saline-related problems in revegetation and may cause boron toxicity in plants. Topsoiling has apparently ameliorated these potential problems for plant growth on mine spoil. Total and extractable concentrations for elements and other parameters for each area of the San Juan Basin provide background information for the evaluation of the chemical quality of soils in each area.

  18. Stratigraphic and geochemical controls on naturally occurring arsenic in groundwater, eastern Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Schreiber, M. E.; Simo, J. A.; Freiberg, P. G.

    High arsenic concentrations (up to 12,000μg/L) have been measured in groundwater from a confined sandstone aquifer in eastern Wisconsin. The main arsenic source is a sulfide-bearing secondary cement horizon (SCH) that has variable thickness, morphology, and arsenic concentrations. Arsenic occurs in pyrite and marcasite as well as in iron oxyhydroxides but not as a separate arsenopyrite phase. Nearly identical sulfur isotopic signatures in pyrite and dissolved sulfate and the correlation between dissolved sulfate, iron, and arsenic concentrations suggest that sulfide oxidation is the dominant process controlling arsenic release to groundwater. However, arsenic-bearing oxyhydroxides can potentially provide another arsenic source if reducing conditions develop or if they are transported as colloids in the aquifer. Analysis of well data indicates that the intersection of the SCH with static water levels measured in residential wells is strongly correlated with high concentrations of arsenic in groundwater. Field and laboratory data suggest that the most severe arsenic contamination is caused by localized borehole interactions of air, water, and sulfides. Although arsenic contamination is caused by oxidation of naturally occurring sulfides, it is influenced by water-level fluctuations caused by municipal well pumping or climate changes, which can shift geographic areas in which contamination occurs. Résumé De fortes concentrations en arsenic, jusqu'à 12000μg/L, ont été mesurées dans l'eau souterraine d'un aquifère gréseux captif, dans l'est du Wisconsin. La principale source d'arsenic est un horizon à cimentation secondaire (SCH) comportant des sulfures, dont l'épaisseur, la morphologie et les concentrations en arsenic sont variables. L'arsenic est présent dans la pyrite et dans la marcassite, de même que dans des oxy-hydroxydes de fer, mais non pas dans une phase séparée d'arsénopyrite. Les signatures isotopiques du soufre presque identiques dans la

  19. The Haughton Impact Structure as an Analogue to Mars: Polygons and the Nature of Their Depositional Environment

    NASA Astrophysics Data System (ADS)

    Godin, E.; Osinski, G. R.

    2016-09-01

    Thermal contraction polygons can differ in definition, aspect, shape, and size. Three types of deposits with respectively distinct polygons near Haughton Impact Structure (Devon Island, NU, Canada) were investigated as analogues to polygons on Mars.

  20. Natural and industrial analogues for release of CO2 from storagereservoirs: Identification of features, events, and processes and lessonslearned

    SciTech Connect

    Lewicki, Jennifer L.; Birkholzer, Jens; Tsang, Chin-Fu

    2006-03-03

    The injection and storage of anthropogenic CO{sub 2} in deep geologic formations is a potentially feasible strategy to reduce CO{sub 2} emissions and atmospheric concentrations. While the purpose of geologic carbon storage is to trap CO{sub 2} underground, CO{sub 2} could migrate away from the storage site into the shallow subsurface and atmosphere if permeable pathways such as well bores or faults are present. Large-magnitude releases of CO{sub 2} have occurred naturally from geologic reservoirs in numerous volcanic, geothermal, and sedimentary basin settings. Carbon dioxide and natural gas have also been released from geologic CO{sub 2} reservoirs and natural gas storage facilities, respectively, due to influences such as well defects and injection/withdrawal processes. These systems serve as natural and industrial analogues for the potential release of CO{sub 2} from geologic storage reservoirs and provide important information about the key features, events, and processes (FEPs) that are associated with releases, as well as the health, safety, and environmental consequences of releases and mitigation efforts that can be applied. We describe a range of natural releases of CO{sub 2} and industrial releases of CO{sub 2} and natural gas in the context of these characteristics. Based on this analysis, several key conclusions can be drawn, and lessons can be learned for geologic carbon storage. First, CO{sub 2} can both accumulate beneath, and be released from, primary and secondary reservoirs with capping units located at a wide range of depths. Both primary and secondary reservoir entrapments for CO{sub 2} should therefore be well characterized at storage sites. Second, many natural releases of CO{sub 2} have been correlated with a specific event that triggered the release, such as magmatic fluid intrusion or seismic activity. The potential for processes that could cause geomechanical damage to sealing cap rocks and trigger the release of CO{sub 2} from a storage

  1. Natural and industrial analogues for leakage of CO2 from storagereservoirs: identification of features, events, and processes and lessonslearned

    SciTech Connect

    Lewicki, Jennifer L.; Birkholzer, Jens; Tsang, Chin-Fu

    2006-02-28

    The injection and storage of anthropogenic CO2 in deepgeologic formations is a potentially feasible strategy to reduce CO2emissions and atmospheric concentrations. While the purpose of geologiccarbon storage is to trap CO2 underground, CO2 could migrate away fromthe storage site into the shallow subsurface and atmosphere if permeablepathways such as well bores or faults are present. Large-magnitudereleases of CO2 have occurred naturally from geologic reservoirs innumerous volcanic, geothermal, and sedimentary basin settings. Carbondioxide and natural gas have also been released from geologic CO2reservoirs and natural gas storage facilities, respectively, due toinfluences such as well defects and injection/withdrawal processes. Thesesystems serve as natural and industrial analogues for the potentialrelease of CO2 from geologic storage reservoirs and provide importantinformation about the key features, events, and processes (FEPs) that areassociated with releases, as well as the health, safety, andenvironmental consequences of releases and mitigation efforts that can beapplied. We describe a range of natural releases of CO2 and industrialreleases of CO2 and natural gas in the context of these characteristics.Based on this analysis, several key conclusions can be drawn, and lessonscan be learned for geologic carbon storage. First, CO2 can bothaccumulate beneath, and be released from, primary and secondaryreservoirs with capping units located at a wide range of depths. Bothprimary and secondary reservoir entrapments for CO2 should therefore bewell characterized at storage sites. Second, many natural releases of CO2have been correlated with a specific event that triggered the release,such as magmatic fluid intrusion or seismic activity. The potential forprocesses that could cause geomechanical damage to sealing cap rocks andtrigger the release of CO2 from a storage reservoir should be evaluated.Third, unsealed fault and fracture zones may act as fast and directconduits

  2. Geochemical evidence concerning the nature of the source region to the Middle Proterozoic Granite-Rhyolite Province

    SciTech Connect

    Shuster, R.D. . Dept. Geography Mueller, P.A.; Heatherington, A.L. . Dept. Geology)

    1992-01-01

    The mostly buried 1.5--1.3 Ga old Granite-Rhyolite Province of the midcontinent of North America, is characterized by extensive, undeformed silicic volcanic rocks and related epizonal granitic plutons. Thirty-three previously dated samples from a wide geographic range (Michigan to Colorado) have been analyzed to determine their chemical and Nd and Pb isotopic compositions in order to constrain source regions and processes involved in the formation of these rocks. Major and trace element analyses of these rocks indicate their anorogenic nature, with relatively high Ce/Nb and Y/Nb ratios, as well as relatively high Ga/Al ratios. Geochemically, these rocks are similar to the A2 granites of Eby (1992), which are thought to be generated from the melting of crust which has experienced at least one cycle of subduction-related magmatism. Rare earth element and Pb isotopic data suggest melting at middle to shallow depths. The isotopic data (Nd and Pb) indicate little to no contribution of Archean crust to the source of these rocks. Initial Pb isotopic ratios (208Pb/204Pb) suggest a low Th/U ratio in the source, which contrasts strongly with high Th/U ratios of the Wyoming Province. The Pb isotopic ratios for these rocks are variable, but cluster about the orogene plumbotectonics curve. The variability in the data suggest sources which are variable in their U/Pb ratios and/or ages. The isotopic data are consistent with the existence of a proposed lithospheric boundary which trend NE-SW through the Granite-Rhyolite Province and separates 1.65 Ga old lithosphere (to the NW) from 1.5 Ga old lithosphere (to the SE). Samples analyzed from either side of this boundary have different isotopic signatures. Many of the samples appear to be derived from sources which are only slightly older than the crystallization ages of the granites themselves.

  3. Formation and geochemical significance of micrometallic aggregates including fissiogenic platinum group elements in the Oklo natural reactor, Gabon

    NASA Astrophysics Data System (ADS)

    Kikuchi, Makiko; Hidaka, Hiroshi; Gauthier-Lafaye, François

    2010-08-01

    Metallic aggregates with a size of a few tens μm and consisting mainly of Ru, Rh, Pd, Te, Pb, As, Sb, S and Bi were found in the acid residue of SD37-S2/CD uraninite taken from Oklo natural reactor zone (RZ) 13. Quantitative analyses of major elements using an electron probe microanalyzer and in situ isotopic analyses of Zr, Mo, Ru, Pb and U using a sensitive high-resolution ion microprobe were performed on the metallic aggregates to determine the geochemical behaviors of fission products and actinides and to ascertain the processes of formation of the aggregates in the RZs. The chemical compositions of the aggregates investigated in this study are significantly different from those reported previously, showing lower Pb content and no correlation between the contents of Pb and S in the individual grains. The 235U/ 238U ratios in metallic aggregates vary significantly from 0.00478 to 0.01466, indicating chemical fractionation between U and Pu during the formation of the aggregates. The Pb isotopic data indicate that most of the Pb in the aggregates decayed from 2.05 Ga-old uraninite that existed in the RZ originally and that there was chemical fractionation between U and Pb in some aggregates. The Zr and Mo isotopic ratios, 90Zr/ 91Zr and 95Mo/ 97Mo, for most of the aggregates had small variations, which can be simply explained by constant separate mixing of fissiogenic and nonfissiogenic components. On the other hand, a large variation in the 99Ru/ 101Ru ratio (0.324-1.73) cannot be explained only by a two component mixing theory; thus, chemical fractionation between Tc and Ru during the reactor criticality is suggested. The large variations in the 235U/ 238U and 99Ru/ 101Ru isotopic ratios suggest that the aggregates formed under various redox conditions owing to the radiolysis of water.

  4. Global profiling and rapid matching of natural products using diagnostic product ion network and in silico analogue database: Gastrodia elata as a case study.

    PubMed

    Lai, Chang-Jiang-Sheng; Zha, Liangping; Liu, Da-Hui; Kang, Liping; Ma, Xiaojing; Zhan, Zhi-Lai; Nan, Tie-Gui; Yang, Jian; Li, Fajie; Yuan, Yuan; Huang, Lu-Qi

    2016-07-22

    Rapid discovery of novel compounds of a traditional herbal medicine is of vital significance for pharmaceutical industry and plant metabolic pathway analysis. However, discovery of unknown or trace natural products is an ongoing challenge. This study presents a universal targeted data-independent acquisition and mining strategy to globally profile and effectively match novel natural product analogues from an herbal extract. The famous medical plant Gastrodia elata was selected as an example. This strategy consists of three steps: (i) acquisition of accurate parent and adduct ions (PAIs) and the product ions data of all eluting compounds by untargeted full-scan MS(E) mode; (ii) rapid compound screening using diagnostic product ions (DPIs) network and in silico analogue database with SUMPRODUCT function to find novel candidates; and (iii) identification and isomerism discrimination of multiple types of compounds using ClogP and ions fragment behavior analyses. Using above data mining methods, a total of 152 compounds were characterized, and 70 were discovered for the first time, including series of phospholipids and novel gastroxyl derivatives. Furthermore, a number of gastronucleosides and phase II metabolites of gastrodin and parishins were discovered, including glutathionylated, cysteinylglycinated and cysteinated compounds, and phosphatidylserine analogues. This study extended the application of classical DPIs filter strategy and developed a structure-based screening approach with the potential for significant increase of efficiency for discovery and identification of trace novel natural products.

  5. Global profiling and rapid matching of natural products using diagnostic product ion network and in silico analogue database: Gastrodia elata as a case study.

    PubMed

    Lai, Chang-Jiang-Sheng; Zha, Liangping; Liu, Da-Hui; Kang, Liping; Ma, Xiaojing; Zhan, Zhi-Lai; Nan, Tie-Gui; Yang, Jian; Li, Fajie; Yuan, Yuan; Huang, Lu-Qi

    2016-07-22

    Rapid discovery of novel compounds of a traditional herbal medicine is of vital significance for pharmaceutical industry and plant metabolic pathway analysis. However, discovery of unknown or trace natural products is an ongoing challenge. This study presents a universal targeted data-independent acquisition and mining strategy to globally profile and effectively match novel natural product analogues from an herbal extract. The famous medical plant Gastrodia elata was selected as an example. This strategy consists of three steps: (i) acquisition of accurate parent and adduct ions (PAIs) and the product ions data of all eluting compounds by untargeted full-scan MS(E) mode; (ii) rapid compound screening using diagnostic product ions (DPIs) network and in silico analogue database with SUMPRODUCT function to find novel candidates; and (iii) identification and isomerism discrimination of multiple types of compounds using ClogP and ions fragment behavior analyses. Using above data mining methods, a total of 152 compounds were characterized, and 70 were discovered for the first time, including series of phospholipids and novel gastroxyl derivatives. Furthermore, a number of gastronucleosides and phase II metabolites of gastrodin and parishins were discovered, including glutathionylated, cysteinylglycinated and cysteinated compounds, and phosphatidylserine analogues. This study extended the application of classical DPIs filter strategy and developed a structure-based screening approach with the potential for significant increase of efficiency for discovery and identification of trace novel natural products. PMID:27318507

  6. An analogue peptide from the Cancer/Testis antigen PASD1 induces CD8+ T cell responses against naturally processed peptide

    PubMed Central

    Hardwick, Nicola; Buchan, Sarah; Ingram, Wendy; Khan, Ghazala; Vittes, Gisella; Rice, Jason; Pulford, Karen; Mufti, Ghulam; Stevenson, Freda; Guinn, Barbara-ann

    2013-01-01

    We have previously identified the novel Cancer/Testis antigen PASD1 by immunoscreening a testis library with pooled acute myeloid leukemia (AML) patient sera. To develop a cytotoxic T lymphocyte (CTL)-inducing vaccine, we have now investigated the carboxy-terminal region, known to contain serological determinants, for MHC class I (HLA-A⋆0201)-binding peptides. Algorithm-selected natural peptides failed to show detectable HLA-A⋆0201 binding in T2 assays. However, anchor-modified analogue peptides showed enhanced binding, with decreased off-rates. Analogue peptide-loaded antigen-presenting cells (APCs) induced IFN-γ production by T cells from normal donors and patients. In addition, peptide-specific T cells could be expanded from cancer patients by stimulation with the PASD1 analogue peptide Pa14. For clinical application, a DNA fusion gene vaccine encoding Pa14 was designed and tested in “humanized” mice. Splenocytes from vaccinated mice showed in vitro cytotoxicity against tumour cells, either exogenously loaded with the corresponding wild-type peptide (Pw8) or expressing endogenously processed PASD1 protein. We show for the first time that a DNA vaccine encoding an altered PASD1 epitope can induce CTLs to target the natural peptide expressed by human tumour cells. PMID:23882161

  7. IRON PRECIPITATION AND ARSENIC ATTENUATION - ASSESSMENT OF ARSENIC NATURAL ATTENUATION OF THE SUBSURFACE USING A GEOCHEMICAL MODEL (PHREEQC)

    EPA Science Inventory

    Laboratory experiments show that amorphous and poorly crystallized ferric iron hydroxides have much greater capacity to attenuate arsenic compared to clays and other aluminosilicate minerals. Studies (e.g., Lin and Qvarfort, 1996) showed that a sudden change in geochemical condit...

  8. Natural Analogues - One Way to Help Build Public Confidence in the Predicted Performance of a Mined Geologic Repository for Nuclear Waste

    SciTech Connect

    Stuckless, J. S.

    2002-02-26

    The general public needs to have a way to judge the predicted long-term performance of the potential high-level nuclear waste repository at Yucca Mountain. The applicability and reliability of mathematical models used to make this prediction are neither easily understood nor accepted by the public. Natural analogues can provide the average person with a tool to assess the predicted performance and other scientific conclusions. For example, hydrologists with the Yucca Mountain Project have predicted that most of the water moving through the unsaturated zone at Yucca Mountain, Nevada will move through the host rock and around tunnels. Thus, seepage into tunnels is predicted to be a small percentage of available infiltration. This hypothesis can be tested experimentally and with some quantitative analogues. It can also be tested qualitatively using a variety of analogues such as (1) well-preserved Paleolithic to Neolithic paintings in caves and rock shelters, (2) biological remains preserved in caves and rock shelters, and (3) artifacts and paintings preserved in man-made underground openings. These examples can be found in materials that are generally available to the non-scientific public and can demonstrate the surprising degree of preservation of fragile and easily destroyed materials for very long periods of time within the unsaturated zone.

  9. Behavioural activity of angiotensin II (3-7)4Phe--analogue of natural fragment 3-7 of angiotensin II.

    PubMed

    Hoły, Z; Wiśniewski, K; Jachimowicz, A; Braszko, J

    1996-01-01

    A study was made of the influence of pentapeptide 3-7 angiotensin II [AII(3-7)], its analogue 3-7(4)Phe [AII(3-7)4Phe] and angiotensin II (AII) on the behaviour of adult male rats. The motility, stereotypy, spatial performance, learning of conditioned and passive avoidance responses allowing to avoid aversive stimulation were estimated. Examined peptides at the dose 1 nmol injected intracerebroventricularly 15 min before the experiment did not produce specific changes in psychomotor activity in the "open field" test and in retention of the spatial task in the Morris water maze. The rate of acquisition of conditioned avoidance responses was stimulated by AII(3-7)4Phe, AII(3-7) and AII administration. In the passive avoidance situation AII improved retention of the responses whereas analogue AII(3-7)4Phe and fragment 3-7 caused similar though less pronounced effect. All the peptides applied immediately before the experiment intensified stereotypy, a behaviour evoked by of apomorphine-1 mg/kg and amphetamine-7.5 mg/kg intraperitonealy injection. These results show similar psychotropic activity of analogue AII(3-7)4Phe, comparable with the activity of natural fragment 3-7 of angiotensin II.

  10. Using and interpreting analogue designs.

    PubMed

    Cook, Bryan G; Rumrill, Phillip D

    2005-01-01

    Researchers in rehabilitation counseling and disability studies sometimes use analogue research, which involves materials that approximate or describe reality (e.g., written vignettes, videotaped exemplars) rather than investigating phenomena in real-world settings. Analogue research often utilizes experimental designs, and it thereby frequently possesses a high degree of internal validity. Analogue research allows investigators to exercise tight control over the implementation of the independent or treatment variable and over potentially confounding variables, which enables them to isolate the effects of those treatment variables on selected outcome measures. However, the simulated nature of analogue research presents an important threat to external validity. As such, the generalizability of analogue research to real-life settings and situations may be problematic. These and other issues germane to analogue research in vocational rehabilitation are discussed in this article, illustrated with examples from the contemporary literature.

  11. The role of natural glasses as analogues in projecting the long-term alteration of high-level nuclear waste glasses: Part 1

    SciTech Connect

    Mazer, J.J.

    1993-12-31

    The common observation of glasses persisting in natural environments for long periods of time (up to tens of millions of years) provides compelling evidence that these materials can be kinetically stable in a variety of subsurface environments. This paper reviews how natural and historical synthesized glasses can be employed as natural analogues for understanding and projecting the long-term alteration of high-level nuclear waste glasses. The corrosion of basaltic glass results in many of the same alteration features found in laboratory testing of the corrosion of high-level radioactive waste glasses. Evidence has also been found indicating similarities in the rate controlling processes, such as the effects of silica concentration on corrosion in groundwater and in laboratory leachates. Naturally altered rhyolitic glasses and tektites provide additional evidence that can be used to constrain estimates of long-term waste glass alteration. When reacted under conditions where water is plentiful, the corrosion for these glasses is dominated by network hydrolysis, while the corrosion is dominated by molecular water diffusion and secondary mineral formation under conditions where water contact is intermittent or where water is relatively scarce. Synthesized glasses that have been naturally altered result in alkali-depleted alteration features that are similar to those found for natural glasses and for nuclear waste glasses. The characteristics of these alteration features appear to be dependent on the alteration conditions which affect the dominant reaction processes during weathering. In all cases, care must be taken to ensure that the information being provided by natural analogues is related to nuclear waste glass corrosion in a clear and meaningful way.

  12. Similarity in drugs: reflections on analogue design.

    PubMed

    Wermuth, Camille G

    2006-04-01

    A survey of novel small-molecule therapeutics reveals that the majority of them result from analogue design and that their market value represents two-thirds of all small-molecule sales. In natural science, the term analogue, derived from the Latin and Greek analogia, has always been used to describe structural and functional similarity. Extended to drugs, this definition implies that the analogue of an existing drug molecule shares structural and pharmacological similarities with the original compound. Formally, this definition allows the establishment of three categories of drug analogues: analogues possessing chemical and pharmacological similarities (direct analogues); analogues possessing structural similarities only (structural analogues); and chemically different compounds displaying similar pharmacological properties (functional analogues). PMID:16580977

  13. Syntheses of (-)-oleocanthal, a natural NSAID found in extra virgin olive oil, the (-)-deacetoxy-oleuropein aglycone, and related analogues.

    PubMed

    Smith, Amos B; Sperry, Jeffrey B; Han, Qiang

    2007-08-31

    Phenolic compounds extracted from extra virgin olive oil have attracted considerable recent attention. One of the components, (-)-oleocanthal (1), an inhibitor of the COX-1 and COX-2 enzymes, possesses similar potency as the NSAID ibuprofen. In this, a full account, we disclose the first- and now second-generation syntheses of both enantiomers of the oleocanthals, as well as the first synthesis of the closely related (-)-deacetoxy-oleuropein aglycone and a series of related analogues for structure activity studies. To demonstrate the utility of the second-generation synthesis, multigram quantities of (-)-oleocanthal were prepared in 10 steps (14% overall yield) from commercially available D-lyxose. PMID:17685574

  14. "One-shot" analysis of PDE-5 inhibitors and analogues in counterfeit herbal natural products using an LC-DAD-QTOF system.

    PubMed

    Bortolini, Claudio; Pivato, Antonio; Bogialli, Sara; Pastore, Paolo

    2015-08-01

    A highly selective and robust method for simultaneous screening and confirmation of target and non-target phosphodiesterase type 5 (PDE-5) inhibitor analogues within a single chromatographic run in counterfeit herbal products was developed. The protocol, based on an easy and rapid extraction with a water/acetonitrile 1 % formic acid solution, followed by sonication and centrifugation, exploits an LC-diode array detector-quadrupole-time-of-flight (DAD-QTOF) system. The extraction method was optimized both at high concentrations and at trace levels. These two situations are typically encountered in pharmaceutical formulations and herbal food supplements. Carryover effects, never reported before and occurring mainly for vardenafil, were overcome using a polymer-based column. An in-house validation was carried out using five blanks of different bulk matrices spiked with seven standard analytes, namely yohimbine, sildenafil, vardenafil, tadalafil, homosildenafil, pseudovardenafil and hydroxyhomovardenafil. Reliable quantitation was possible using a conventional standard solution for all the pharmaceutical and herbal samples considered, as matrix effects were eliminated. Accuracy ranged from 80.9 to 108.1 % with overall relative standard deviation (RSD) <11 % (N = 15), measured at 1.0, 5.0 and 10.0 μg/g. Limits of detection (LODs) obtained ensured the determination of cross contaminations at nanogram per gram levels. A database with 82 PDE-5 inhibitor analogues was implemented for automatic non-target analysis. Among the 26 samples of dietary supplements and herbal remedies bulk marketed for erectile dysfunctions, three samples were found to be contaminated with both registered and unregistered synthetic PDE-5 inhibitors, i.e. yohimbine, sildenafil, dimethylsildenafil and thiodimethylsildenafil or thiomethisosildenafil. The occurrence of such contaminations, both at trace levels and at pharmaceutical dosage, indicates the illicit use of synthetic PDE-5 analogues

  15. "One-shot" analysis of PDE-5 inhibitors and analogues in counterfeit herbal natural products using an LC-DAD-QTOF system.

    PubMed

    Bortolini, Claudio; Pivato, Antonio; Bogialli, Sara; Pastore, Paolo

    2015-08-01

    A highly selective and robust method for simultaneous screening and confirmation of target and non-target phosphodiesterase type 5 (PDE-5) inhibitor analogues within a single chromatographic run in counterfeit herbal products was developed. The protocol, based on an easy and rapid extraction with a water/acetonitrile 1 % formic acid solution, followed by sonication and centrifugation, exploits an LC-diode array detector-quadrupole-time-of-flight (DAD-QTOF) system. The extraction method was optimized both at high concentrations and at trace levels. These two situations are typically encountered in pharmaceutical formulations and herbal food supplements. Carryover effects, never reported before and occurring mainly for vardenafil, were overcome using a polymer-based column. An in-house validation was carried out using five blanks of different bulk matrices spiked with seven standard analytes, namely yohimbine, sildenafil, vardenafil, tadalafil, homosildenafil, pseudovardenafil and hydroxyhomovardenafil. Reliable quantitation was possible using a conventional standard solution for all the pharmaceutical and herbal samples considered, as matrix effects were eliminated. Accuracy ranged from 80.9 to 108.1 % with overall relative standard deviation (RSD) <11 % (N = 15), measured at 1.0, 5.0 and 10.0 μg/g. Limits of detection (LODs) obtained ensured the determination of cross contaminations at nanogram per gram levels. A database with 82 PDE-5 inhibitor analogues was implemented for automatic non-target analysis. Among the 26 samples of dietary supplements and herbal remedies bulk marketed for erectile dysfunctions, three samples were found to be contaminated with both registered and unregistered synthetic PDE-5 inhibitors, i.e. yohimbine, sildenafil, dimethylsildenafil and thiodimethylsildenafil or thiomethisosildenafil. The occurrence of such contaminations, both at trace levels and at pharmaceutical dosage, indicates the illicit use of synthetic PDE-5 analogues

  16. Hydrologic and geochemical data collected near Skewed Reservoir, an impoundment for coal-bed natural gas produced water, Powder River Basin, Wyoming

    USGS Publications Warehouse

    Healy, Richard W.; Rice, Cynthia A.; Bartos, Timothy T.

    2012-01-01

    The Powder River Structural Basin is one of the largest producers of coal-bed natural gas (CBNG) in the United States. An important environmental concern in the Basin is the fate of groundwater that is extracted during CBNG production. Most of this produced water is disposed of in unlined surface impoundments. A 6-year study of groundwater flow and subsurface water and soil chemistry was conducted at one such impoundment, Skewed Reservoir. Hydrologic and geochemical data collected as part of that study are contained herein. Data include chemistry of groundwater obtained from a network of 21 monitoring wells and three suction lysimeters and chemical and physical properties of soil cores including chemistry of water/soil extracts, particle-size analyses, mineralogy, cation-exchange capacity, soil-water content, and total carbon and nitrogen content of soils.

  17. Of the necessity of knowledge of the natural pedo-geochemical background content in the evaluation of the contamination of soils by trace elements.

    PubMed

    Baize, D; Sterckeman, T

    2001-01-01

    In order to evaluate the contamination of the Dornach (Switzerland) site within the framework of the CEEM-Soil project, each participating team was allowed to take a maximum of 15 samples. The French team's sampling was organized in such a way as to answer the following questions: (i) what is the natural concentration of the soils at this site (local pedo-geochemical background content)?; (ii) what are the levels of Cd, Cu, Pb and Zn contamination of the soil?; (iii) what is the depth reached by the surface contamination that is derived from atmospheric fallout?; (iv) how is the contamination spread along the longest axis of the area under study? The relationships between total Fe and the trace metals have allowed local variations in the natural pedo-geochemical background content to be detected and thus permitted the anthropogenic contamination to be estimated. There would appear to be a low level of Pb contamination over all the site investigated (an increase of the order of 5-10 mg kg(-1) on the background level), limited to the surface humus-bearing layers. There is also a significant contamination by Cu over all of the site (an increase of the order of 30-40 mg kg(-1)). This contamination has remained in the surface horizons (0-20 cm). Very high Zn and Cd concentrations have been found in the four surface (0-4 cm) and deep horizons (15-70 cm) taken under the forest and very much lower values in the samples taken from cultivated soils. The most likely explanation is an unequal inheritance between the upper part of the site (wooded with thinner very clayey soils) and the lower cultivated part of the site (with thicker less clayey soils developed in a loamy material). For various reasons, it seems unlikely that a contamination of the wooded part should be so much higher than the cultivated part due to the interception of atmospheric dust by the trees. The local pedo-geochemical background Cd and Zn content of the upper wooded part proved to be clearly higher than

  18. Of the necessity of knowledge of the natural pedo-geochemical background content in the evaluation of the contamination of soils by trace elements.

    PubMed

    Baize, D; Sterckeman, T

    2001-01-01

    In order to evaluate the contamination of the Dornach (Switzerland) site within the framework of the CEEM-Soil project, each participating team was allowed to take a maximum of 15 samples. The French team's sampling was organized in such a way as to answer the following questions: (i) what is the natural concentration of the soils at this site (local pedo-geochemical background content)?; (ii) what are the levels of Cd, Cu, Pb and Zn contamination of the soil?; (iii) what is the depth reached by the surface contamination that is derived from atmospheric fallout?; (iv) how is the contamination spread along the longest axis of the area under study? The relationships between total Fe and the trace metals have allowed local variations in the natural pedo-geochemical background content to be detected and thus permitted the anthropogenic contamination to be estimated. There would appear to be a low level of Pb contamination over all the site investigated (an increase of the order of 5-10 mg kg(-1) on the background level), limited to the surface humus-bearing layers. There is also a significant contamination by Cu over all of the site (an increase of the order of 30-40 mg kg(-1)). This contamination has remained in the surface horizons (0-20 cm). Very high Zn and Cd concentrations have been found in the four surface (0-4 cm) and deep horizons (15-70 cm) taken under the forest and very much lower values in the samples taken from cultivated soils. The most likely explanation is an unequal inheritance between the upper part of the site (wooded with thinner very clayey soils) and the lower cultivated part of the site (with thicker less clayey soils developed in a loamy material). For various reasons, it seems unlikely that a contamination of the wooded part should be so much higher than the cultivated part due to the interception of atmospheric dust by the trees. The local pedo-geochemical background Cd and Zn content of the upper wooded part proved to be clearly higher than

  19. Corosolic acid analogue, a natural triterpenoid saponin, induces apoptosis on human hepatocarcinoma cells through mitochondrial pathway in vitro.

    PubMed

    Qu, Liping; Zhang, Huiqing; Yang, Yanlong; Yang, Geliang; Xin, Hailiang; Ling, Changquan

    2016-08-01

    Context 2a,-3a,-24-Trihydroxyurs-12-en-28-oic acid (TEO, a corosolic acid analogue) is a triterpenoid saponin isolated from Actinidia valvata Dunn (Actinidiaceae), a well-known traditional Chinese medicine. Objective This study investigated the anti-proliferation and inducing apoptosis effects of TEO in three human hepatocellular carcinoma (HCC) cell lines. Materials and methods Cytotoxic activity of TEO was determined by the MTT assay at various concentrations from 2.5 to 40 μg/mL in BEL-7402, BEL-7404 and SMMC-7721 cell lines. Cell morphology was assessed by acridine orange/ethidium bromide and 4'-6-diamidino-2-phenylindole dihydrochloride staining and fluorescence microscopy. Cell-cycle distribution and DNA damage were determined by flow cytometry and comet assay. Mitochondrial dysfunction was assessed by JC-1 staining and transmission electron microscopy. Apoptosis changes were explored by Western blot, TNF-α and caspase-3, -8, -9 assays. Results TEO exhibited inhibition effects on BEL-7402, BEL-7404 and SMMC-7721 cells treated for 24 h, the IC50 values were 34.6, 30.8 and 30.5 μg/mL, respectively. TEO (40 μg/mL)-treated three cell lines increased by more than 21% in the G1 phase and presented the morphological change and DNA damage. TEO also declined the mitochondrial membrane potential and altered mitochondrial ultra-structure. Furthermore, caspase-3, caspase-8, caspase-9 and TNF-α were also activated. Mechanism investigation showed that TEO could decrease anti-apoptotic Bcl-2 protein expression, increase proapoptotic Bax and Bid proteins expressions and increase Bax/Bcl-2 ratio. Conclusion Our results demonstrate for the first time that TEO inhibited growth of HCC cell lines and induced G1 phase arrest. Moreover, proapoptotic effects of TEO were mediated through the activation of TNF-α, caspases and mitochondrial pathway. PMID:26810384

  20. Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquife

    SciTech Connect

    Campbell, K M; K Kukkadapu, R K; Qafoku, N P; Peacock, A D; Lesher, E; Williams, K H; Bargar, J R; Wilkins, M J; Figueroa, L; Ranville, J; Davis, J A; Long, P E

    2012-05-23

    Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology and redox processes that occur in these zones, several cores from a region of naturally occurring reducing conditions in a U-contaminated aquifer (Rifle, CO) were examined. Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for U and Fe content, oxidation state, and mineralogy; reduced S phases; and solid-phase organic C content using a suite of analytical and spectroscopic techniques on bulk sediment and size fractions. Solid-phase U concentrations were higher in the naturally reduced zone, with a high proportion of the U present as U(IV). The sediments were also elevated in reduced S phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and SO4 reduction has occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentrations of solid-phase organic C and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic C concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic C for maintaining reducing conditions and U immobilization.

  1. Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer

    SciTech Connect

    Campbell, Kate M.; Kukkadapu, Ravi K.; Qafoku, Nikolla; Peacock, Aaron D.; Lesher, E.; Williams, Kenneth H.; Bargar, John R.; Wilkins, Michael J.; Figueroa, Linda A.; Ranville, James; Davis, James; Long, Philip E.

    2012-05-23

    Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology, and redox processes that occur in these zones, we examined several cores from a region of naturally occurring reducing conditions in a uranium-contaminated aquifer (Rifle, CO). Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for uranium and iron content, oxidation state, and mineralogy, reduced sulfur phases, and solid phase organic carbon content using a suite of analytical and spectroscopic techniques on bulk sediment and size fractions. Solid-phase uranium concentrations were higher in the naturally reduced zone, with a high proportion of the uranium present as reduced U(IV). The sediments were also elevated in reduced sulfur phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and sulfate reduction occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentration of solid phase organic carbon and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic carbon concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic carbon for maintaining reducing conditions and uranium immobilization.

  2. Geochemical, mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer

    SciTech Connect

    Campbell, K. M.; Kukkadapu, R. K.; Qafoku, N. P.; Peacock, A. D.; Lesher, E.; Williams, K. H.; Bargar, J. R.; Wilkins, M. J.; Figueroa, L.; Ranville, J.; Davis, J. A.; Long, P. E.

    2012-08-01

    Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology and redox processes that occur in these zones, several cores from a region of naturally occurring reducing conditions in a U-contaminated aquifer (Rifle, CO) were examined. Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for U and Fe content, oxidation state, and mineralogy; reduced S phases; and solid-phase organic C content using a suite of analytical and spectroscopic techniques on bulk sediment and size fractions. Solid-phase U concentrations were higher in the naturally reduced zone, with a high proportion of the U present as U(IV). The sediments were also elevated in reduced S phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and SO4 reduction has occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentrations of solid-phase organic C and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic C concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic C for maintaining reducing conditions and U immobilization.

  3. Geological and geochemical criteria for the continental nature of the Mendeleev Rise (the Arctic Ocean) from the data of drilling and dredging of seabed rock material

    NASA Astrophysics Data System (ADS)

    Morozov, Andrey; Petrov, Oleg; Kremenetskiy, Alexander; Kashubin, Sergey; Rekant, Pavel; Gusev, Eugene; Shokalskiy, Sergey; Shevchenko, Sergey; Sergeev, Sergey; Artyushkov, Eugene

    2013-04-01

    The results are presented of geological and geophysical studies on the Mendeleev Rise at 10 test sites at 79°N to 83°N (expedition "Arktika-2012" in August-September 2012). During the expedition, for the first time, three boreholes were drilled in the bedrocks of the Mendeleev Rise basement at a depth of 1700-2600 m, and more than 20 thousand fragments of seabed rock material were dredged. Among them carbonate-bearing rocks including dolomite with relicts of trilobites and ostracoderms (D3-C) constitute up 65 %. Up to 20% are terrigenous rocks with a predominance of quartz sandstones. Magmatic rocks constitute 10-15% of the samples (including 8% of gabbro-dolerite and 2 % of granite) with 5% of metamorphic rocks. The boreholes revealed magmatic mafic rocks of basalt to basaltic andesite to trachyandesite series (SiO2-48-58% K2O+Na2O-3,4-9,2%) including epigenically altered volcanic breccias. All fragments of magmatic mafic rocks have a similar mineral and chemical composition and are grouped with gabbro dolerite (SiO2-49-51%, K2O+Na2O-2,5-3,0%). Preliminary results of mineralogic, geochemical and of isotopic geochemical (ICP-OEC, ICP-MS, RFA, Sm-Nd, Rb-Sr, EPMA and others) analyses suggest the continental nature of the studied rocks and show a distinct difference from rocks of the Gakkel Ridge in the Eurasian part of the ocean, which are of the oceanic origin. U-Pb dating of zircons from the core rocks and seabed rock material (SIMS SHRIMP II) indicate a wide range of their formation age: 2940-995, 639-385 and 303-203 Ma and thus suggest that they belong to volcanogenic terrigeneous carbonate-bearing bed of the ancient platform composing the floor of Amerasian part of the Arctic Ocean.

  4. Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill samples from the Powder River basin, Wyoming

    USGS Publications Warehouse

    See, R.B.; Reddy, K.J.; Vance, G.F.; Fadlelmawla, A.A.; Blaylock, M.J.

    1995-01-01

    Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill aquifers were investigated. Backfill and ground-water samples were collected at coal mines in the Powder River Basin, Wyoming. Backfill was generally dominated by aluminum (14,400 to 49,000 mg/kg (milligrams per kilogram)), iron (3,330 to 23,200 mg/kg), and potassium (7,950 to 18,000 mg/kg). Backfill saturated-paste selenium concentrations ranged from 1 to 156 mg/kg (microsiemens per kilogram). Ground-water total selenium concentrations ranged from 3 to 125 mg/L. Dissolved organic carbon in all ground-water samples was dominated by hydrophobic and hydrophilic acids (38 to 84 percent). Selenite sorption/desorption experiments were conducted using background solutions of distilled-deionized water, 0.1 molar calcium chloride, and isolated hydrophobic and hydrophilic acids. Selenite sorption was larger when 0.1 molar calcium chloride was used. The addition of hydrophilic acid decreased selenite sorption more than the addition of hydrophobic acids. Geochemical modelling was used to predict the solid phases controlling dissolved selenium concentrations and to evaluate the effects of dissolved organic carbon on selenium solubility. Results suggested that 55 to 90 percent of selenium in backfill precipitation/dissolution extracts was dominated by magnesium selenate ion pairs. Dissolved organic carbon had little effect on selenium speciation. A redox chamber was constructed to control Eh and pH in water and backfill-core sample suspensions. The response of selenite and selenate in water samples to redox conditions did not follow thermodynamic predictions. Reduction of selenate in water samples did not occur at any of the redox levels tested.

  5. Clastic dikes of the Hatrurim basin (western flank of the Dead Sea) as natural analogues of alkaline concretes: Mineralogy, solution chemistry, and durability

    NASA Astrophysics Data System (ADS)

    Sokol, E. V.; Gaskova, O. L.; Kozmenko, O. A.; Kokh, S. N.; Vapnik, E. A.; Novikova, S. A.; Nigmatulina, E. N.

    2014-11-01

    This study shows that the mineral assemblages from clastic dikes in areas adjacent to the Dead Sea graben may be considered as natural analogues of alkaline concretes. The main infilling material of the clastic dikes is composed of well-sorted and well-rounded quartz sand. The cement of these hard rocks contains hydroxylapophyllite, tacharanite, calcium silicate hydrates, opal, calcite, and zeolite-like phases, which is indicative of a similarity of the natural cementation processes and industrial alkaline concrete production from quartz sands and industrial alkaline cements. The quartz grains exhibit a variety of reaction textures reflecting the interaction with alkaline solutions (opal and calcium hydrosilicate overgrowths; full replacement with apophyllite or thomsonite + apophyllite). The physicochemical analysis and reconstruction of the chemical composition of peralkaline Ca, Na, and K solutions that formed these assemblages reveal that the solutions evolved toward a more stable composition of zeolite-like phases, which are more resistant to long-term chemical weathering and atmospheric corrosion. The 40Ar/39Ar age of 6.2 ± 0.7 Ma obtained for apophyllite provides conclusive evidence for the high corrosion resistance of the assemblages consisting of apophyllite and zeolite-like phases.

  6. Structural Revisions of a Class of Natural Products: Scaffolds of Aglycon Analogues of Fusicoccins and Cotylenins Isolated from Fungi.

    PubMed

    Tang, Ying; Xue, Yongbo; Du, Guang; Wang, Jianping; Liu, Junjun; Sun, Bin; Li, Xiao-Nian; Yao, Guangmin; Luo, Zengwei; Zhang, Yonghui

    2016-03-14

    The reisolation and structural revision of brassicicene D is described, and inspired us to reassign the core skeletons of brassicicenes C-H, J and K, ranging from dicyclopenta[a,d]cyclooctane to tricyclo[9.2.1.0(3,7)]tetradecane using quantum-chemical predictions and experimental validation strategies. Three novel, highly modified fusicoccanes, brassicicenes L-N, were also isolated from the fungus Alternaria brassicicola, and their structures were unequivocally established by spectroscopic data, ECD calculations, and crystallography. The reassigned structures represent the first class of bridgehead double-bond-containing natural products with a bicyclo[6.2.1]undecane carbon skeleton. Furthermore, their stabilities were first predicted with olefin strain energy calculations. Collectively, these findings extend our view of the application of computational predictions and biosynthetic logic-based structure elucidation to address problems related to the structure and stability of natural products. PMID:26916098

  7. Geochemical analysis of atlantic rim water, carbon county, wyoming: New applications for characterizing coalbed natural gas reservoirs

    USGS Publications Warehouse

    McLaughlin, J.F.; Frost, C.D.; Sharma, Shruti

    2011-01-01

    Coalbed natural gas (CBNG) production typically requires the extraction of large volumes of water from target formations, thereby influencing any associated reservoir systems. We describe isotopic tracers that provide immediate data on the presence or absence of biogenic natural gas and the identify methane-containing reservoirs are hydrologically confined. Isotopes of dissolved inorganic carbon and strontium, along with water quality data, were used to characterize the CBNG reservoirs and hydrogeologic systems of Wyoming's Atlantic Rim. Water was analyzed from a stream, springs, and CBNG wells. Strontium isotopic composition and major ion geochemistry identify two groups of surface water samples. Muddy Creek and Mesaverde Group spring samples are Ca-Mg-S04-type water with higher 87Sr/86Sr, reflecting relatively young groundwater recharged from precipitation in the Sierra Madre. Groundwaters emitted from the Lewis Shale springs are Na-HCO3-type waters with lower 87Sr/86Sr, reflecting sulfate reduction and more extensive water-rock interaction. To distinguish coalbed waters, methanogenically enriched ??13CDIC wasused from other natural waters. Enriched ??13CDIC, between -3.6 and +13.3???, identified spring water that likely originates from Mesaverde coalbed reservoirs. Strongly positive ??13CDIC, between +12.6 and +22.8???, identified those coalbed reservoirs that are confined, whereas lower ??13CDIC, between +0.0 and +9.9???, identified wells within unconfined reservoir systems. Copyright ?? 2011. The American Association of Petroleum Geologists. All rights reserved.

  8. Comparison of shallow aquifer and soil gas monitoring approaches for detecting CO2 leakage at a natural analogue site in France

    NASA Astrophysics Data System (ADS)

    Widory, D.; Gal, F.; Proust, E.; Mayer, B.

    2011-12-01

    Natural analogue sites where geologic CO2 is leaking to the surface provide excellent opportunities to test approaches suitable for monitoring for potential CO2 leakage at carbon capture and storage sites. We tested isotope monitoring approaches for CO2 detection in shallow aquifers and the overlying soil zone at a CO2 analogue site near Sainte-Marguerite in the Massif Central (France). The Sainte-Marguerite area is located in the southern part of the Limagne graben (French Massif Central). The basement, composed of highly fractured granite, outcrops toward the west of the study area, notably around the Saladis spring. An intercalated arkosic permeable interval between fractured granite and Oligocene marls and limestones acts as a stratiform drain for fluid migration while the overlying thick Oligocene interval is impermeable and acts as a seal. The Allier river bed is located near the contact between the basement and the sedimentary rocks. Deep CO2-ladden fluids migrate through the arkose interval toward the Sainte-Marguerite area and sustain a number of local springs. The Sainte-Marguerite area is known for the travertine deposits associated with the CO2-rich natural springs. We collected water samples and effervescent gases at the springs as well as soil gases for chemical and isotopic analyses. The analytical parameters included major anions and cations, δ13C & δ18O of CO2, δD & δ18O of H2O and δ13C of dissolved inorganic carbon (DIC). Preliminary results revealed that δ13C values of CO2 in most groundwater and soil samples were similar. Oxygen isotope measurements revealed equilibrium between CO2 and H2O-oxygen in most samples, but except for a limited number of samples, δ18O values of water did not deviate significantly from the local meteoric water line. Our preliminary results suggest that both the groundwater and the soil sampling approaches should be capable of detecting leakage of CO2 provided that the leaking gas has a distinct isotopic

  9. Synthesis of high-mannose oligosaccharide analogues through click chemistry: true functional mimics of their natural counterparts against lectins?

    PubMed

    François-Heude, Marc; Méndez-Ardoy, Alejandro; Cendret, Virginie; Lafite, Pierre; Daniellou, Richard; Ortiz Mellet, Carmen; García Fernández, José M; Moreau, Vincent; Djedaïni-Pilard, Florence

    2015-01-26

    Terminal "high-mannose oligosaccharides" are involved in a broad range of biological and pathological processes, from sperm-egg fusion to influenza and human immunodeficiency virus infections. In spite of many efforts, their synthesis continues to be very challenging and actually represents a major bottleneck in the field. Whereas multivalent presentation of mannopyranosyl motifs onto a variety of scaffolds has proven to be a successful way to interfere in recognition processes involving high-mannose oligosaccharides, such constructs fail at reproducing the subtle differences in affinity towards the variety of protein receptors (lectins) and antibodies susceptible to binding to the natural ligands. Here we report a family of functional high-mannose oligosaccharide mimics that reproduce not only the terminal mannopyranosyl display, but also the core structure and the branching pattern, by replacing some inner mannopyranosyl units with triazole rings. Such molecular design can be implemented by exploiting "click" ligation strategies, resulting in a substantial reduction of synthetic cost. The binding affinities of the new "click" high-mannose oligosaccharide mimics towards two mannose specific lectins, namely the plant lectin concanavalin A (ConA) and the human macrophage mannose receptor (rhMMR), have been studied by enzyme-linked lectin assays and found to follow identical trends to those observed for the natural oligosaccharide counterparts. Calorimetric determinations against ConA, and X-ray structural data support the conclusion that these compounds are not just another family of multivalent mannosides, but real "structural mimics" of the high-mannose oligosaccharides.

  10. Linked metatranscriptomic and geochemical data indicate microbial succession in naturally reduced aquifer sediments dominated by H2-oxidizing Comamonadaceae

    NASA Astrophysics Data System (ADS)

    Jewell, T. N. M.; Karaoz, U.; Bill, M.; Chakraborty, R.; Brodie, E.; Williams, K. H.; Beller, H. R.

    2015-12-01

    In this study, we sought to better understand what natural organic matter fuels heterotrophic microbial communities in the anoxic subsurface at the Rifle (CO) site and what genes may be diagnostic of that activity. We conducted a 20-day microcosm experiment with naturally reduced zone (NRZ) sediments and collected replicate samples every 5 days for omics (metagenome and metatranscriptome) and biogeochemical measurements (e.g., continuous CO2 production, H2, CH4, acetate, DOC, Fe(II), sulfate, NH4+, spectroscopic analyses of sediment OM). No electron donors were added other than the NRZ sediment, which is enriched in organic matter relative to typical Rifle aquifer material. The microcosms were constructed and incubated under anaerobic conditions in serum bottles with a N2headspace. Biogeochemical measurements indicate that the decomposition of native organic matter occurred in different phases, including depletion of DOC and release of CO2 during the first week of incubation, followed by a pulse of acetogenesis and methanogenesis after 2 weeks (with acetogenesis dominating carbon flux after 2 weeks). While H2 remained below detection levels throughout the study, a peak of [NiFe] uptake hydrogenase, acetyl-CoA synthetase, urease, and nitrate reductase transcripts belonging to the Comamonadaceae family occurred at day 15. Some members of Comamonadaceae are facultative H2-oxidizing chemolithoautotrophs and fix carbon via the acetogenic Wood-Ljungdahl pathway. Comamonadaceae plateaued at 73% of the metagenome at this time and represented 69% of the metatranscriptome, succeeding the S-oxidizing Sulfurimonas genus. Sulfurimonas species were the dominant group at day 0, accounting for 43% of the metagenome and 25% of the metatranscriptome, decreasing to 11% in both the metagenome and metatranscriptome by day 10. Less abundant but still present were transcripts for genes involved in cellulose degradation (glycosyl hydrolases), and glycolysis (phosphofructokinase

  11. Groundwater and Associated Solute Contribution to a Pristine Semi-Arid Estuary Using Resistivity Imaging, Naturally Occurring Radioactive Tracers, and Geochemical Methods.

    NASA Astrophysics Data System (ADS)

    Spalt, N.; Murgulet, D.; Douglas, A. R.

    2015-12-01

    Geophysical, geochemical, and Naturally Occurring Radioactive Tracers (NORTs) were used in a semi-arid National Estuarine Research Reserve to estimate Submarine Groundwater Discharge (SGD) rates and nutrient fluxes. SGD has been identified as an important source of limiting nutrients to coastal ecosystems, and is conceivably even more critical in a dry climate. Groundwater inflows are rarely considered in estuary mass budgets, therefore sampling stations were chosen over the entire bay system to identify spatial differences in SGD and to estimate direct groundwater contributions. This interdisciplinary approach proved necessary to differentiate between the bay recirculation and terrestrial components of SGD. Resistivity measurements using a towed electrode array were used to identify sampling stations at areas favorable to SGD. While NORTs may provide an estimate of basin-wide groundwater input, these sampling stations ascertain the favorable geologic environment for hydraulic interconnectivity between surface water and groundwater in the system. A sampling suite (including metals and nutrients) of surface, bottom, and pore waters during winter and summer months display spatio-temporal changes in nutrient fluxes. This study reinforces the understanding of the necessity to use multiple methods to accurately quantify SGD and associated solute fluxes and advances the knowledge of coastal groundwater interaction in semi-arid environments.

  12. Geochemical survey of Levante Bay, Vulcano Island (Italy), a natural laboratory for the study of ocean acidification.

    PubMed

    Boatta, F; D'Alessandro, W; Gagliano, A L; Liotta, M; Milazzo, M; Rodolfo-Metalpa, R; Hall-Spencer, J M; Parello, F

    2013-08-30

    Shallow submarine gas vents in Levante Bay, Vulcano Island (Italy), emit around 3.6t CO2 per day providing a natural laboratory for the study of biogeochemical processes related to seabed CO2 leaks and ocean acidification. The main physico-chemical parameters (T, pH and Eh) were measured at more than 70 stations with 40 seawater samples were collected for chemical analyses. The main gas vent area had high concentrations of dissolved hydrothermal gases, low pH and negative redox values all of which returned to normal seawater values at distances of about 400m from the main vents. Much of the bay around the vents is corrosive to calcium carbonate; the north shore has a gradient in seawater carbonate chemistry that is well suited to studies of the effects of long-term increases in CO2 levels. This shoreline lacks toxic compounds (such as H2S) and has a gradient in carbonate saturation states.

  13. A combined methodology using electrical resistivity tomography, ordinary kriging and porosimetry for quantifying total C trapped in carbonate formations associated with natural analogues for CO2 leakage

    NASA Astrophysics Data System (ADS)

    Prado-Pérez, A. J.; Aracil, E.; Pérez del Villar, L.

    2014-06-01

    Currently, carbon deep geological storage is one of the most accepted methods for CO2 sequestration, being the long-term behaviour assessment of these artificial systems absolutely essential to guarantee the safety of the CO2 storage. In this sense, hydrogeochemical modelling is being used for evaluating any artificial CO2 deep geological storage as a potential CO2 sinkhole and to assess the leakage processes that are usually associated with these engineered systems. Carbonate precipitation, as travertines or speleothems, is a common feature in the CO2 leakage scenarios and, therefore, is of the utmost importance to quantify the total C content trapped as a stable mineral phase in these carbonate formations. A methodology combining three classical techniques such as: electrical resistivity tomography, geostatistical analysis and mercury porosimetry is described in this work, which was developed for calculating the total amount of C trapped as CaCO3 associated with the CO2 leakages in Alicún de las Torres natural analogue (Granada, Spain). The proposed methodology has allowed estimating the amount of C trapped as calcite, as more than 1.7 Mt. This last parameter, focussed on an artificial CO2 deep geological storage, is essential for hydrogeochemical modellers when evaluating whether CO2 storages constitute or not CO2 sinkholes. This finding is extremely important when assessing the long-term behaviour and safety of any artificial CO2 deep geological storage.

  14. Total synthesis and biological evaluation of a series of macrocyclic hybrids and analogues of the antimitotic natural products dictyostatin, discodermolide, and taxol.

    PubMed

    Paterson, Ian; Naylor, Guy J; Gardner, Nicola M; Guzmán, Esther; Wright, Amy E

    2011-02-01

    The design, synthesis, and biological evaluation of a series of hybrids and analogues of the microtubule-stabilizing anticancer agents dictyostatin, discodermolide, and taxol is described. A 22-membered macrolide scaffold was prepared by adapting earlier synthetic routes directed towards dictyostatin and discodermolide, taking advantage of the distinctive structural and stereochemical similarities between these two polyketide-derived marine natural products. Initial endeavors towards accessing novel discodermolide/dictyostatin hybrids led to the adoption of a late-stage diversification strategy and the construction of a small library of methyl-ether derivatives, along with the first triple hybrids bearing the side-chain of taxol or taxotere attached through an ester linkage. Biological assays of the anti-proliferative activity of these compounds in a series of human cancer cell lines, including the taxol-resistant NCI/ADR-Res cell line, allowed the proposal of various structure-activity relationships. This led to the identification of a potent macrocyclic discodermolide/dictyostatin hybrid 12 and its C9 methoxy derivative 38, accessible by an efficient total synthesis and with a similar biological profile to dictyostatin.

  15. Geochemical survey of Levante Bay, Vulcano Island (Italy), a natural laboratory for the study of ocean acidification.

    PubMed

    Boatta, F; D'Alessandro, W; Gagliano, A L; Liotta, M; Milazzo, M; Rodolfo-Metalpa, R; Hall-Spencer, J M; Parello, F

    2013-08-30

    Shallow submarine gas vents in Levante Bay, Vulcano Island (Italy), emit around 3.6t CO2 per day providing a natural laboratory for the study of biogeochemical processes related to seabed CO2 leaks and ocean acidification. The main physico-chemical parameters (T, pH and Eh) were measured at more than 70 stations with 40 seawater samples were collected for chemical analyses. The main gas vent area had high concentrations of dissolved hydrothermal gases, low pH and negative redox values all of which returned to normal seawater values at distances of about 400m from the main vents. Much of the bay around the vents is corrosive to calcium carbonate; the north shore has a gradient in seawater carbonate chemistry that is well suited to studies of the effects of long-term increases in CO2 levels. This shoreline lacks toxic compounds (such as H2S) and has a gradient in carbonate saturation states. PMID:23465567

  16. Geochemical behavior of radionuclides in highly altered zircon above the Bangombé natural fission reactor, Gabon

    NASA Astrophysics Data System (ADS)

    Kikuchi, Makiko; Hidaka, Hiroshi; Horie, Kenji

    The isotopic compositions of rare earth elements (REE), Pb and U of highly altered zircons from the clay and black shale layers above the Bangombé natural reactor, Gabon, were determined by a sensitive high resolution ion microprobe (SHRIMP) to discuss the redistribution processes of elements into zircons under the supergene weathering. The clay layer trapped most of the fissiogenic Nd, Sm and Eu derived from the reactor and prevented them migrating into the black shale layer. On the other hand, only the Ce isotopic ratios of the clay and black shale layers have about 2 times larger variations than the other REE. This result suggests that a large chemical fractionation between Ce and other REE above the reactor occurred under the oxidizing condition. The U-Pb data of zircons suggest that the U-Pb system was largely disturbed by migration of chemically fractionated Pb and U from the 2.0 Ga-old uraninite in association with recent weathering.

  17. Geochemical and Isotopic Analysis of Escaped Natural Gases in Hydraulically Fractured and non-Fractured sites in Cumberland Forest, Tennessee

    NASA Astrophysics Data System (ADS)

    Ajayi, M.; Ayers, J. C.; Hornberger, G. M.

    2015-12-01

    Methane (CH4) in the atmosphere accounts for 18% of the climate warming attributed to greenhouse gases. The rapid growth in high volume hydraulic fracturing (HVHF) technologies to procure natural gas raises concern for possible fugitive methane leaks. We measure the flux and carbon isotope composition of methane emitted from the soil into the atmosphere at two geologically similar sites in eastern Tennessee (Morgan Co.), one with HVHF ongoing and the other currently undeveloped. Our objective is to quantify potential non-point source emissions of microbial and thermogenic methane, which are principally distinguished by their δ13C signatures. Using cavity ring down spectroscopy (Picarro G2201-i) we collect rapid (~1 Hz) real-time measurements of methane emissions. The Picarro can measure fluxes of CH4 and CO2 at discrete locations by measuring their concentrations within a static and closed chamber that allows the gases to accumulate over time. Additionally, the mobility of the Picarro instrument permits the continuous collection of data, enabling broad spatial coverage. Applying geostatistical techniques to these data can highlight heterogeneities in the emissions of methane. Trends of where, how much, and what type of methane is escaping from the soil in environments with and without HVHF activities illustrate how to compare and contrast points as well as areas to assess the impact of this extensively implemented method of fossil fuel development.

  18. Progression of natural attenuation processes at a crude-oil spill site . I. Geochemical evolution of the plume

    USGS Publications Warehouse

    Cozzarelli, I.M.; Bekins, B.A.; Baedecker, M.J.; Aiken, G.R.; Eganhouse, R.P.; Tuccillo, M.E.

    2001-01-01

    A 16-year study of a hydrocarbon plume shows that the extent of contaminant migration and compound-specific behavior have changed as redox reactions, most notably iron reduction, have progressed over time. Concentration changes at a small scale, determined from analysis of pore-water samples drained from aquifer cores, are compared with concentration changes at the plume scale, determined from analysis of water samples from an observation well network. The small-scale data show clearly that the hydrocarbon plume is growing slowly as sediment iron oxides are depleted. Contaminants, such as ortho-xylene that appeared not to be moving downgradient from the oil on the basis of observation well data, are migrating in thin layers as the aquifer evolves to methanogenic conditions. However, the plume-scale observation well data show that the downgradient extent of the Fe2+ and BTEX plume did not change between 1992 and 1995. Instead, depletion of the unstable Fe (III) oxides near the subsurface crude-oil source has caused the maximum dissolved iron concentration zone within the plume to spread at a rate of approximately 3 m/year. The zone of maximum concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) has also spread within the anoxic plume. In monitoring the remediation of hydrocarbon-contaminated ground water by natural attenuation, subtle concentration changes in observation well data from the anoxic zone may be diagnostic of depletion of the intrinsic electron-accepting capacity of the aquifer. Recognition of these subtle patterns may allow early prediction of growth of the hydrocarbon plume. Copyright ?? 2001 .

  19. Progression of natural attenuation processes at a crude-oil spill site. I. Geochemical evolution of the plume

    NASA Astrophysics Data System (ADS)

    Cozzarelli, Isabelle M.; Bekins, Barbara A.; Baedecker, Mary Jo; Aiken, George R.; Eganhouse, Robert P.; Tuccillo, Mary Ellen

    2001-12-01

    A 16-year study of a hydrocarbon plume shows that the extent of contaminant migration and compound-specific behavior have changed as redox reactions, most notably iron reduction, have progressed over time. Concentration changes at a small scale, determined from analysis of pore-water samples drained from aquifer cores, are compared with concentration changes at the plume scale, determined from analysis of water samples from an observation well network. The small-scale data show clearly that the hydrocarbon plume is growing slowly as sediment iron oxides are depleted. Contaminants, such as ortho-xylene that appeared not to be moving downgradient from the oil on the basis of observation well data, are migrating in thin layers as the aquifer evolves to methanogenic conditions. However, the plume-scale observation well data show that the downgradient extent of the Fe 2+ and BTEX plume did not change between 1992 and 1995. Instead, depletion of the unstable Fe (III) oxides near the subsurface crude-oil source has caused the maximum dissolved iron concentration zone within the plume to spread at a rate of approximately 3 m/year. The zone of maximum concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) has also spread within the anoxic plume. In monitoring the remediation of hydrocarbon-contaminated ground water by natural attenuation, subtle concentration changes in observation well data from the anoxic zone may be diagnostic of depletion of the intrinsic electron-accepting capacity of the aquifer. Recognition of these subtle patterns may allow early prediction of growth of the hydrocarbon plume.

  20. Geophysical and geochemical nature of relaminated arc-derived lower crust underneath oceanic domain in southern Mongolia

    NASA Astrophysics Data System (ADS)

    Guy, Alexandra; Schulmann, Karel; Janoušek, Vojtech; Štípská, Pavla; Armstrong, Robin; Belousova, Elena; Dolgopolova, Alla; Seltmann, Reimar; Lexa, Ondrej; Jiang, Yingde; Hanžl, Pavel

    2016-04-01

    The Central Asian Orogenic Belt (CAOB) in southern Mongolia consists of E-W trending Neoproterozoic cratons and Silurian-Devonian oceanic tectonic zones. Previous study revealed that the Early Paleozoic accretionary wedge and the oceanic tectonic zone are underlain by a layer giving a homogeneous gravity signal. Forward gravity modelling suggests that this layer is not formed of high-density material typical of lower oceanic crust but is composed of low- to intermediate-density rocks resembling continental crust. The nature of this lower crust is constrained by the whole-rock geochemistry and zircon Hf isotopic signature of abundant Late Carboniferous high-K calc-alkaline and Early Permian A-type granitoids intruding the two Early Paleozoic domains. It is possible to explain the genesis of these granitoids by anatexis of juvenile, metaigneous (tonalitic-gabbroic) rocks of Late Cambrian age, the source of which is presumed to lie in the "Khantaishir" arc (520-495Ma) further north. In order to test this hypothesis, the likely modal composition and density of Khantaishir arc-like protoliths are thermodynamically modelled at granulite- and higher amphibolite-facies conditions. It is shown that the current average density of the lower crust inferred by gravity modelling (2730 ±20kg/m3) matches best metamorphosed leucotonalite to diorite. Based on these results, it is now proposed that Mongolian CAOB has an architecture in which the accretionary wedge and oceanic upper crust is underlain by allochthonous lower crust that originated in a Cambrian arc. A tectonic model explaining relamination of allochthonous felsic to intermediate lower crust beneath mafic upper crust is proposed.

  1. Geophysical and geochemical nature of relaminated arc-derived lower crust underneath oceanic domain in southern Mongolia

    NASA Astrophysics Data System (ADS)

    Guy, Alexandra; Schulmann, Karel; Janoušek, Vojtěch; Å típská, Pavla; Armstrong, Robin; Belousova, Elena; Dolgopolova, Alla; Seltmann, Reimar; Lexa, Ondrej; Jiang, Yingde; Hanžl, Pavel

    2015-05-01

    The Central Asian Orogenic Belt (CAOB) in southern Mongolia consists of E-W trending Neoproterozoic cratons and Silurian-Devonian oceanic tectonic zones. Previous study revealed that the Early Paleozoic accretionary wedge and the oceanic tectonic zone are underlain by a layer giving a homogeneous gravity signal. Forward gravity modelling suggests that this layer is not formed of high-density material typical of lower oceanic crust but is composed of low- to intermediate-density rocks resembling continental crust. The nature of this lower crust is constrained by the whole-rock geochemistry and zircon Hf isotopic signature of abundant Late Carboniferous high-K calc-alkaline and Early Permian A-type granitoids intruding the two Early Paleozoic domains. It is possible to explain the genesis of these granitoids by anatexis of juvenile, metaigneous (tonalitic-gabbroic) rocks of Late Cambrian age, the source of which is presumed to lie in the "Khantaishir" arc (520-495 Ma) further north. In order to test this hypothesis, the likely modal composition and density of Khantaishir arc-like protoliths are thermodynamically modelled at granulite- and higher amphibolite-facies conditions. It is shown that the current average density of the lower crust inferred by gravity modelling (2730 ± 20 kg/m3) matches best metamorphosed leucotonalite to diorite. Based on these results, it is now proposed that Mongolian CAOB has an architecture in which the accretionary wedge and oceanic upper crust is underlain by allochthonous lower crust that originated in a Cambrian arc. A tectonic model explaining relamination of allochthonous felsic to intermediate lower crust beneath mafic upper crust is proposed.

  2. Progression of natural attenuation processes at a crude-oil spill site: I. Geochemical evolution of the plume.

    PubMed

    Cozzarelli, I M; Bekins, B A; Baedecker, M J; Aiken, G R; Eganhouse, R P; Tuccillo, M E

    2001-12-15

    A 16-year study of a hydrocarbon plume shows that the extent of contaminant migration and compound-specific behavior have changed as redox reactions, most notably iron reduction, have progressed over time. Concentration changes at a small scale, determined from analysis of pore-water samples drained from aquifer cores, are compared with concentration changes at the plume scale, determined from analysis of water samples from an observation well network. The small-scale data show clearly that the hydrocarbon plume is growing slowly as sediment iron oxides are depleted. Contaminants, such as ortho-xylene that appeared not to be moving downgradient from the oil on the basis of observation well data, are migrating in thin layers as the aquifer evolves to methanogenic conditions. However, the plume-scale observation well data show that the downgradient extent of the Fe2+ and BTEX plume did not change between 1992 and 1995. Instead, depletion of the unstable Fe (III) oxides near the subsurface crude-oil source has caused the maximum dissolved iron concentration zone within the plume to spread at a rate of approximately 3 m/year. The zone of maximum concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) has also spread within the anoxic plume. In monitoring the remediation of hydrocarbon-contaminated ground water by natural attenuation, subtle concentration changes in observation well data from the anoxic zone may be diagnostic of depletion of the intrinsic electron-accepting capacity of the aquifer. Recognition of these subtle patterns may allow early prediction of growth of the hydrocarbon plume.

  3. A Nucleotide-Analogue-Induced Gain of Function Corrects the Error-Prone Nature of Human DNA Polymerase iota

    SciTech Connect

    Ketkar, Amit; Zafar, Maroof K.; Banerjee, Surajit; Marquez, Victor E.; Egli, Martin; Eoff, Robert L.

    2012-10-25

    Y-family DNA polymerases participate in replication stress and DNA damage tolerance mechanisms. The properties that allow these enzymes to copy past bulky adducts or distorted template DNA can result in a greater propensity for them to make mistakes. Of the four human Y-family members, human DNA polymerase iota (hpol{iota}) is the most error-prone. In the current study, we elucidate the molecular basis for improving the fidelity of hpol{iota} through use of the fixed-conformation nucleotide North-methanocarba-2{prime}-deoxyadenosine triphosphate (N-MC-dATP). Three crystal structures were solved of hpol{iota} in complex with DNA containing a template 2{prime}-deoxythymidine (dT) paired with an incoming dNTP or modified nucleotide triphosphate. The ternary complex of hpol{iota} inserting N-MC-dATP opposite dT reveals that the adenine ring is stabilized in the anti orientation about the pseudo-glycosyl torsion angle, which mimics precisely the mutagenic arrangement of dGTP:dT normally preferred by hpol{iota}. The stabilized anti conformation occurs without notable contacts from the protein but likely results from constraints imposed by the bicyclo[3.1.0]hexane scaffold of the modified nucleotide. Unmodified dATP and South-MC-dATP each adopt syn glycosyl orientations to form Hoogsteen base pairs with dT. The Hoogsteen orientation exhibits weaker base-stacking interactions and is less catalytically favorable than anti N-MC-dATP. Thus, N-MC-dATP corrects the error-prone nature of hpol{iota} by preventing the Hoogsteen base-pairing mode normally observed for hpol{iota}-catalyzed insertion of dATP opposite dT. These results provide a previously unrecognized means of altering the efficiency and the fidelity of a human translesion DNA polymerase.

  4. Sonic and resistivity measurements on Berea sandstone containing tetrahydrofuran hydrates: a possible analogue to natural-gas-hydrate deposits. [Tetrahydrofuran hydrates

    SciTech Connect

    Pearson, C.; Murphy, J.; Halleck, P.; Hermes, R.; Mathews, M.

    1983-01-01

    Deposits of natural gas hydrates exist in arctic sedimentary basins and in marine sediments on continental slopes and rises. However, the physical properties of such sediments are largely unknown. In this paper, we report laboratory sonic and resistivity measurements on Berea sandstone cores saturated with a stoichiometric mixture of tetrahydrofuran (THF) and water. We used THF as the guest species rather than methane or propane gas because THF can be mixed with water to form a solution containing proportions of the proper stoichiometric THF and water. Because neither methane nor propane is soluble in water, mixing the guest species with water sufficiently to form solid hydrate is difficult. Because THF solutions form hydrates readily at atmospheric pressure it is an excellent experimental analogue to natural gas hydrates. Hydrate formation increased the sonic P-wave velocities from a room temperature value of 2.5 km/s to 4.5 km/s at -5/sup 0/C when the pores were nearly filled with hydrates. Lowering the temperature below -5/sup 0/C did not appreciably change the velocity however. In contrast, the electrical resistivity increases nearly two orders of magnitude upon hydrate formation and continues to increase more slowly as the temperature is further decreased. In all cases the resistivities are nearly frequency independent to 30 kHz and the loss tangents are high, always greater than 5. The dielectric loss shows a linear decrease with frequency suggesting that ionic conduction through a brine phase dominates at all frequencies, even when the pores are nearly filled with hydrates. We find that the resistivities are strongly a function of the dissolved salt content of the pore water. Pore water salinity also influences the sonic velocity, but this effect is much smaller and only important near the hydrate formation temperature.

  5. The effect of long-term fluid-rock interactions on the mechanical properties of reservoir rock - a case study of the Werkendam natural CO2 analogue field

    NASA Astrophysics Data System (ADS)

    Hangx, Suzanne; Bertier, Pieter; Bakker, Elisenda; Nover, Georg; Busch, Andreas

    2015-04-01

    Geological storage of CO2 is one of the most promising technologies to rapidly reduce anthropogenic emissions of carbon dioxide. During long-term geological storage of CO2, fluid-rock interactions, induced by the formation of carbonic acid, may affect the mineralogical composition of the reservoir rock. Commonly expected reactions include the dissolution of carbonate and/or sulphate cements, as well as the reaction of primary minerals (feldspars, clays, micas) to form new, secondary phases. In order to ensure storage integrity, it is important to understand the effect of such fluid-rock interactions on the mechanical behaviour of a CO2 storage complex. However, most of these reactions are very slow, which limits the ability to study coupled chemical-mechanical processes in the lab. A possible way to circumvent long reaction times is to investigate natural CO2 analogue fields, which experienced CO2-exposure for thousands of years. In this study, we looked at the Dutch Werkendam natural CO2 field and its unreacted counterpart (Röt Fringe Sandstone, Werkendam, the Netherlands). We focussed on CO2-induced mineralogical and porosity-permeability changes, and their effect on mechanical behaviour of intact rock. Overall, CO2-exposure did not lead to drastic mineralogical changes, though markedly different porosity-permeability relationships were found for the unreacted and exposed material. The limited extent of reaction was in part the result of bitumen coatings protecting specific mineral phases from reaction. In local, mm-sized zones displaying significant anhydrite dissolution, enhanced porosity was observed. For most of the reservoir the long-term mechanical behaviour after CO2-exposure could be described by the behaviour of the unreacted sandstone, while these more 'porous' zones were significantly weaker. Simple stress path calculations predict that reservoir failure due to depletion and injection is unlikely.

  6. The role of anthropogenic and natural factors in shaping the geochemical evolution of groundwater in the Subei Lake basin, Ordos energy base, Northwestern China.

    PubMed

    Liu, Fei; Song, Xianfang; Yang, Lihu; Han, Dongmei; Zhang, Yinghua; Ma, Ying; Bu, Hongmei

    2015-12-15

    Groundwater resources are increasingly exploited for industrial and agricultural purposes in many arid regions globally, it is urgent to gain the impact of the enhanced anthropogenic pressure on the groundwater chemistry. The aim of this study was to acquire a comprehensive understanding of the evolution of groundwater chemistry and to identify the impact of natural and anthropogenic factors on the groundwater chemistry in the Subei Lake basin, Northwestern China. A total of 153 groundwater samples were collected and major ions were measured during the three campaigns (August and December 2013, May 2014). At present, the major hydrochemical facies in unconfined groundwater are Ca-Mg-HCO3, Ca-Na-HCO3, Na-Ca-HCO3, Na-HCO3, Ca-Mg-SO4 and Na-SO4-Cl types, while the main hydrochemical facies in confined groundwater are Ca-Mg-HCO3, Ca-Na-HCO3, Na-Ca-HCO3, Ca-HCO3 and Na-HCO3 types. Relatively greater seasonal variation can be observed in the chemical constituents of confined groundwater than that of unconfined groundwater. Rock weathering predominates the evolution of groundwater chemistry in conjunction with the cation exchange, and the dissolution/precipitation of gypsum, halite, feldspar, calcite and dolomite are responsible for the chemical constituents of groundwater. Anthropogenic activities can be classified as: (1) groundwater overexploitation; (2) excessive application of fertilizers in agricultural areas. Due to intensive groundwater pumping, the accelerated groundwater mineralization resulted in the local changes in hydrochemical facies of unconfined groundwater, while the strong mixture, especially a large influx of downward leakage from the unconfined aquifer into the confined aquifer, played a vital role in the fundamental variation of hydrochemical facies in confined aquifer. The nitrate contamination is mainly controlled by the local hydrogeological settings coupled with the traditional flood irrigation. The deeper insight into geochemical evolution of

  7. Chemical-mechanical coupling observed for depleted oil reservoirs subjected to long-term CO2-exposure - A case study of the Werkendam natural CO2 analogue field

    NASA Astrophysics Data System (ADS)

    Hangx, Suzanne; Bakker, Elisenda; Bertier, Pieter; Nover, Georg; Busch, Andreas

    2015-10-01

    Geological storage of CO2 is one of the most promising technologies to rapidly reduce anthropogenic emissions of carbon dioxide. In order to ensure storage integrity, it is important to understand the effect of long-term CO2/brine/rock interactions on the mechanical behaviour of a storage complex. As most of these reactions are too slow to reproduce on laboratory timescales, we studied a natural CO2 analogue reservoir (the Röt Fringe Sandstone, Werkendam field, the Netherlands; 125-135 Ma of CO2-exposure) and its unreacted counterpart. We focused on CO2-induced mineralogical and porosity-permeability changes, and their effect on mechanical behaviour of both intact rock and simulated fault gouge. Overall, CO2-exposure did not lead to drastic mineralogical changes. The CO2-exposed material shows a stronger dependence of permeability on porosity, which is attributed to differences in diagenesis (closed-system diagenesis and hydrocarbon emplacement) taking place before CO2 charging. The limited extent of reaction was in part the result of bitumen coatings protecting specific mineral phases from reaction. In local, mm-sized zones displaying significant anhydrite cement dissolution, enhanced porosity was observed. For most of the reservoir the long-term mechanical behaviour after CO2-exposure could be described by the behaviour of the unreacted sandstone, while these more 'porous' zones had a lower rock strength. In addition, CO2-exposure did not affect the fault friction behaviour, and slip is expected to result in stable sliding. Simple stress path calculations predict that reservoir failure due to depletion and injection is unlikely, even for the 'porous' zones, nor will fault reactivation occur for realistic injection scenarios.

  8. Solution-phase parallel synthesis of a pharmacophore library of HUN-7293 analogues: a general chemical mutagenesis approach to defining structure-function properties of naturally occurring cyclic (depsi)peptides.

    PubMed

    Chen, Yan; Bilban, Melitta; Foster, Carolyn A; Boger, Dale L

    2002-05-15

    HUN-7293 (1), a naturally occurring cyclic heptadepsipeptide, is a potent inhibitor of cell adhesion molecule expression (VCAM-1, ICAM-1, E-selectin), the overexpression of which is characteristic of chronic inflammatory diseases. Representative of a general approach to defining structure-function relationships of such cyclic (depsi)peptides, the parallel synthesis and evaluation of a complete library of key HUN-7293 analogues are detailed enlisting solution-phase techniques and simple acid-base liquid-liquid extractions for isolation and purification of intermediates and final products. Significant to the design of the studies and unique to solution-phase techniques, the library was assembled superimposing a divergent synthetic strategy onto a convergent total synthesis. An alanine scan and N-methyl deletion of each residue of the cyclic heptadepsipeptide identified key sites responsible for or contributing to the biological properties. The simultaneous preparation of a complete set of individual residue analogues further simplifying the structure allowed an assessment of each structural feature of 1, providing a detailed account of the structure-function relationships in a single study. Within this pharmacophore library prepared by systematic chemical mutagenesis of the natural product structure, simplified analogues possessing comparable potency and, in some instances, improved selectivity were identified. One potent member of this library proved to be an additional natural product in its own right, which we have come to refer to as HUN-7293B (8), being isolated from the microbial strain F/94-499709.

  9. SEDIMENT GEOCHEMICAL MODEL

    EPA Science Inventory

    Until recently, sediment geochemical models (diagenetic models) have been only able to explain sedimentary flux and concentration profiles for a few simplified geochemical cycles (e.g., nitrogen, carbon and sulfur). However with advances in numerical methods, increased accuracy ...

  10. Geologic and geochemical systematics of the occurrence of nonhydrocarbon gases: Towards working models to forecast CO{sub 2}, H{sub 2}S and N{sub 2} in natural gas

    SciTech Connect

    Imbus, S.W.; Bissada, K.K.; Urwongse, T.

    1995-12-31

    Despite recent progress towards understanding the mechanisms responsible for generation of many of the naturally occurring non-hydrocarbon gases, no globally applicable set of geologic or geochemical criteria has been developed to elucidate their origin or forecast their abundance in natural gas systems. The present study attempts to identify empirical relationships between the occurrence of these non-hydrocarbon gases and specific geological conditions including tectonic/structural setting; prevalent lithostratigraphy: present and paleo-geothermal and hydrothermal conditions; source rock type and thermal maturity; reservoir lithology and temperature; etc. The use of geochemical data (molecular and isotopic compositions) to assess the relative importance of the diverse controls (in terms of {open_quotes}basin{close_quotes} vs. {open_quotes}reservoir{close_quotes}, organic vs. inorganic, chemical vs. physicochemical factors) will also be examined in the context of the observations. The incorporation of more detailed geologic observations into this basic framework should provide the basis for working-out the geologic/geochemical systematics. This is a most critical step in developing the ultimate forecasting model.

  11. TAPIR--Finnish national geochemical baseline database.

    PubMed

    Jarva, Jaana; Tarvainen, Timo; Reinikainen, Jussi; Eklund, Mikael

    2010-09-15

    In Finland, a Government Decree on the Assessment of Soil Contamination and Remediation Needs has generated a need for reliable and readily accessible data on geochemical baseline concentrations in Finnish soils. According to the Decree, baseline concentrations, referring both to the natural geological background concentrations and the diffuse anthropogenic input of substances, shall be taken into account in the soil contamination assessment process. This baseline information is provided in a national geochemical baseline database, TAPIR, that is publicly available via the Internet. Geochemical provinces with elevated baseline concentrations were delineated to provide regional geochemical baseline values. The nationwide geochemical datasets were used to divide Finland into geochemical provinces. Several metals (Co, Cr, Cu, Ni, V, and Zn) showed anomalous concentrations in seven regions that were defined as metal provinces. Arsenic did not follow a similar distribution to any other elements, and four arsenic provinces were separately determined. Nationwide geochemical datasets were not available for some other important elements such as Cd and Pb. Although these elements are included in the TAPIR system, their distribution does not necessarily follow the ones pre-defined for metal and arsenic provinces. Regional geochemical baseline values, presented as upper limit of geochemical variation within the region, can be used as trigger values to assess potential soil contamination. Baseline values have also been used to determine upper and lower guideline values that must be taken into account as a tool in basic risk assessment. If regional geochemical baseline values are available, the national guideline values prescribed in the Decree based on ecological risks can be modified accordingly. The national geochemical baseline database provides scientifically sound, easily accessible and generally accepted information on the baseline values, and it can be used in various

  12. TAPIR--Finnish national geochemical baseline database.

    PubMed

    Jarva, Jaana; Tarvainen, Timo; Reinikainen, Jussi; Eklund, Mikael

    2010-09-15

    In Finland, a Government Decree on the Assessment of Soil Contamination and Remediation Needs has generated a need for reliable and readily accessible data on geochemical baseline concentrations in Finnish soils. According to the Decree, baseline concentrations, referring both to the natural geological background concentrations and the diffuse anthropogenic input of substances, shall be taken into account in the soil contamination assessment process. This baseline information is provided in a national geochemical baseline database, TAPIR, that is publicly available via the Internet. Geochemical provinces with elevated baseline concentrations were delineated to provide regional geochemical baseline values. The nationwide geochemical datasets were used to divide Finland into geochemical provinces. Several metals (Co, Cr, Cu, Ni, V, and Zn) showed anomalous concentrations in seven regions that were defined as metal provinces. Arsenic did not follow a similar distribution to any other elements, and four arsenic provinces were separately determined. Nationwide geochemical datasets were not available for some other important elements such as Cd and Pb. Although these elements are included in the TAPIR system, their distribution does not necessarily follow the ones pre-defined for metal and arsenic provinces. Regional geochemical baseline values, presented as upper limit of geochemical variation within the region, can be used as trigger values to assess potential soil contamination. Baseline values have also been used to determine upper and lower guideline values that must be taken into account as a tool in basic risk assessment. If regional geochemical baseline values are available, the national guideline values prescribed in the Decree based on ecological risks can be modified accordingly. The national geochemical baseline database provides scientifically sound, easily accessible and generally accepted information on the baseline values, and it can be used in various

  13. Synthesis and analgesic profile of conformationally constrained N-acylhydrazone analogues: discovery of novel N-arylideneamino quinazolin-4(3H)-one compounds derived from natural safrole.

    PubMed

    Maia, Rodolfo C; Silva, Leandro L; Mazzeu, Eduardo F; Fumian, Milla M; de Rezende, Claudia M; Doriguetto, Antonio C; Corrêa, Rodrigo S; Miranda, Ana Luisa P; Barreiro, Eliezer J; Fraga, Carlos Alberto Manssour

    2009-09-15

    In this work we reported the synthesis and evaluation of the analgesic, anti-inflammatory, and platelet anti-aggregating properties of new 3-(arylideneamino)-2-methyl-6,7-methylenedioxy-quinazolin-4(3H)-one derivatives (3a-j), designed as conformationally constrained analogues of analgesic 1,3-benzodioxolyl-N-acylhydrazones (1) previously developed at LASSBio. Target compounds were synthesized in very good yields exploiting abundant Brazilian natural product safrole (2) as starting material. The pharmacological assays lead us to identify compounds LASSBio-1240 (3b) and LASSBio-1272 (3d) as new analgesic prototypes, presenting an antinociceptive profile more potent and effective than dipyrone and indomethacin used, respectively, as standards in AcOH-induced abdominal constrictions assay and in the formalin test. These results confirmed the success in the exploitation of conformation restriction strategy for identification of novel cyclic N-acylhydrazone analogues with optimized analgesic profile.

  14. The role of anthropogenic and natural factors in shaping the geochemical evolution of groundwater in the Subei Lake basin, Ordos energy base, Northwestern China.

    PubMed

    Liu, Fei; Song, Xianfang; Yang, Lihu; Han, Dongmei; Zhang, Yinghua; Ma, Ying; Bu, Hongmei

    2015-12-15

    Groundwater resources are increasingly exploited for industrial and agricultural purposes in many arid regions globally, it is urgent to gain the impact of the enhanced anthropogenic pressure on the groundwater chemistry. The aim of this study was to acquire a comprehensive understanding of the evolution of groundwater chemistry and to identify the impact of natural and anthropogenic factors on the groundwater chemistry in the Subei Lake basin, Northwestern China. A total of 153 groundwater samples were collected and major ions were measured during the three campaigns (August and December 2013, May 2014). At present, the major hydrochemical facies in unconfined groundwater are Ca-Mg-HCO3, Ca-Na-HCO3, Na-Ca-HCO3, Na-HCO3, Ca-Mg-SO4 and Na-SO4-Cl types, while the main hydrochemical facies in confined groundwater are Ca-Mg-HCO3, Ca-Na-HCO3, Na-Ca-HCO3, Ca-HCO3 and Na-HCO3 types. Relatively greater seasonal variation can be observed in the chemical constituents of confined groundwater than that of unconfined groundwater. Rock weathering predominates the evolution of groundwater chemistry in conjunction with the cation exchange, and the dissolution/precipitation of gypsum, halite, feldspar, calcite and dolomite are responsible for the chemical constituents of groundwater. Anthropogenic activities can be classified as: (1) groundwater overexploitation; (2) excessive application of fertilizers in agricultural areas. Due to intensive groundwater pumping, the accelerated groundwater mineralization resulted in the local changes in hydrochemical facies of unconfined groundwater, while the strong mixture, especially a large influx of downward leakage from the unconfined aquifer into the confined aquifer, played a vital role in the fundamental variation of hydrochemical facies in confined aquifer. The nitrate contamination is mainly controlled by the local hydrogeological settings coupled with the traditional flood irrigation. The deeper insight into geochemical evolution of

  15. Assessment of CO2 discharge in a spring using time-variant stable carbon isotope data as a natural analogue study of CO2 leakage

    NASA Astrophysics Data System (ADS)

    Yu, Soonyoung; Chae, Gitak; Jo, Minki; Kim, Jeong-Chan; Yun, Seong-Taek

    2015-04-01

    CO2-rich springs have been studied as a natural analogue of CO2 leakage through shallow subsurface environment, as they provide information on the behaviors of CO2 during the leakage from geologic CO2 storage sites. For this study, we monitored the δ13C values as well as temperature, pH, EC, DO, and alkalinity for a CO2-rich spring for 48 hours. The water samples (N=47) were collected every hour in stopper bottles without headspace to avoid the interaction with air and the CO2 degassing. The δ13C values of total dissolved inorganic carbon (TDIC) in the water samples were analyzed using a cavity ring-down spectroscopy (CRDS) system (Picarro). The values of δ13CTDIC, temperature, pH, EC, DO, and alkalinity were in the range of -9.43 ~ -8.91 o 12.3 ~ 13.2oC, 4.86 ~ 5.02, 186 ~ 189 μS/cm, 1.8 ~ 3.4 mg/L, and 0.74 ~ 0.95 meq/L, respectively. The concentrations of TDIC calculated using pH and alkalinity values were between 22.5 and 34.8 mmol/L. The δ13CTDIC data imply that dissolved carbon in the spring was derived from a deep-seated source (i.e., magmatic) that was slightly intermixed with soil CO2. Careful examination of the time-series variation of measured parameters shows the following characteristics: 1) the δ13CTDIC values are negatively correlated with pH (r = -0.59) and positively correlated with TDIC (r = 0.58), and 2) delay times of the change of pH and alkalinity following the change of δ13CTDIC values are 0 and -3 hours, respectively; the pH change occurs simultaneously with the change of δ13CTDIC, while the alkalinity change happens before 3 hours. Our results indicate that the studied CO2-rich spring is influenced by the intermittent supply of deep-seated CO2. [Acknowledgment] This work was financially supported by the fundamental research project of KIGAM and partially by the "Geo-Advanced Innovative Action (GAIA) Project (2014000530003)" from Korea Ministry of Environment (MOE).

  16. The Green River natural analogue as a field laboratory to study the long-term fate of CO2 in the subsurface

    NASA Astrophysics Data System (ADS)

    Busch, Andreas; Kampman, Niko; Hangx, Suzanne; Bertier, Pieter; Bickle, Mike; Harrington, Jon

    2015-04-01

    served as a direct comparison to the altered samples. We obtained geomechanical, mineralogical, geochemical and petrophysical laboratory data along the entire length of the core and from the control samples. Furthermore, we performed more detailed studies through portions of the caprock in direct contact with the CO2-charged reservoirs. This was done to constrain the nature and penetration depths of the CO2-promoted fluid-mineral reaction fronts. These reactions have taken place in the last ~100,000 years, which has been set as an upper limit for the onset of CO2 influx into the formations. This data has been used as input for reactive (transport) modeling. In addition, we compared geomechanical data from the CO2 -exposed core and the unreacted control samples to assess the mechanical stability of reservoir and seal rocks in a CO2 storage complex following mineral dissolution and precipitation for thousands of years.

  17. Planetary habitability: lessons learned from terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Preston, Louisa J.; Dartnell, Lewis R.

    2014-01-01

    Terrestrial analogue studies underpin almost all planetary missions and their use is essential in the exploration of our Solar system and in assessing the habitability of other worlds. Their value relies on the similarity of the analogue to its target, either in terms of their mineralogical or geochemical context, or current physical or chemical environmental conditions. Such analogue sites offer critical ground-truthing for astrobiological studies on the habitability of different environmental parameter sets, the biological mechanisms for survival in extreme environments and the preservation potential and detectability of biosignatures. The 33 analogue sites discussed in this review have been selected on the basis of their congruence to particular extraterrestrial locations. Terrestrial field sites that have been used most often in the literature, as well as some lesser known ones which require greater study, are incorporated to inform on the astrobiological potential of Venus, Mars, Europa, Enceladus and Titan. For example, the possibility of an aerial habitable zone on Venus has been hypothesized based on studies of life at high-altitudes in the terrestrial atmosphere. We also demonstrate why many different terrestrial analogue sites are required to satisfactorily assess the habitability of the changing environmental conditions throughout Martian history, and recommend particular sites for different epochs or potential niches. Finally, habitable zones within the aqueous environments of the icy moons of Europa and Enceladus and potentially in the hydrocarbon lakes of Titan are discussed and suitable analogue sites proposed. It is clear from this review that a number of terrestrial analogue sites can be applied to multiple planetary bodies, thereby increasing their value for astrobiological exploration. For each analogue site considered here, we summarize the pertinent physiochemical environmental features they offer and critically assess the fidelity with which

  18. Design and Synthesis of Analogues of Marine Natural Product Galaxamide, an N-methylated Cyclic Pentapeptide, as Potential Anti-Tumor Agent in Vitro.

    PubMed

    Lunagariya, Jignesh; Zhong, Shenghui; Chen, Jianwei; Bai, Defa; Bhadja, Poonam; Long, Weili; Liao, Xiaojian; Tang, Xiaoli; Xu, Shihai

    2016-01-01

    Herein, we report design and synthesis of novel 26 galaxamide analogues with N-methylated cyclo-pentapeptide, and their in vitro anti-tumor activity towards the panel of human tumor cell line, such as, A549, A549/DPP, HepG2 and SMMC-7721 using MTT assay. We have also investigated the effect of galaxamide and its representative analogues on growth, cell-cycle phases, and induction of apoptosis in SMMC-7721 cells in vitro. Reckon with the significance of conformational space and N-Me aminoacid (aa) comprising this compound template, we designed the analogues with modification in N-Me-aa position, change in aa configuration from l to d aa and substitute one Leu-aa to d/l Phe-aa residue with respective to the parent structure. The efficient solid phase parallel synthesis approach is employed for the linear pentapeptide residue containing N-Me aa, followed by solution phase macrocyclisation to afford target cyclo pentapeptide compounds. In the present study, all galaxamide analogues exhibited growth inhibition in A549, A549/DPP, SMMC-7721 and HepG2 cell lines. Compounds 6, 18, and 22 exhibited interesting activities towards all cell line tested, while Compounds 1, 4, 15, and 22 showed strong activity towards SMMC-7221 cell line in the range of 1-2 μg/mL IC50. Flow cytometry experiment revealed that galaxamide analogues namely Compounds 6, 18, and 22 induced concentration dependent SMMC-7721 cell apoptosis after 48 h. These compounds induced G0/G1 phase cell-cycle arrest and morphological changes indicating induction of apoptosis. Thus, findings of our study suggest that the galaxamide and its analogues 6, 18 and 22 exerted growth inhibitory effect on SMMC-7721 cells by arresting the cell cycle in the G0/G1 phase and inducing apoptosis. Compound 1 showed promising anti-tumor activity towards SMMC-7721 cancer cell line, which is 9 and 10 fold higher than galaxamide and reference DPP (cisplatin), respectively. PMID:27598177

  19. Design and Synthesis of Analogues of Marine Natural Product Galaxamide, an N-methylated Cyclic Pentapeptide, as Potential Anti-Tumor Agent in Vitro

    PubMed Central

    Lunagariya, Jignesh; Zhong, Shenghui; Chen, Jianwei; Bai, Defa; Bhadja, Poonam; Long, Weili; Liao, Xiaojian; Tang, Xiaoli; Xu, Shihai

    2016-01-01

    Herein, we report design and synthesis of novel 26 galaxamide analogues with N-methylated cyclo-pentapeptide, and their in vitro anti-tumor activity towards the panel of human tumor cell line, such as, A549, A549/DPP, HepG2 and SMMC-7721 using MTT assay. We have also investigated the effect of galaxamide and its representative analogues on growth, cell-cycle phases, and induction of apoptosis in SMMC-7721 cells in vitro. Reckon with the significance of conformational space and N-Me aminoacid (aa) comprising this compound template, we designed the analogues with modification in N-Me-aa position, change in aa configuration from l to d aa and substitute one Leu-aa to d/l Phe-aa residue with respective to the parent structure. The efficient solid phase parallel synthesis approach is employed for the linear pentapeptide residue containing N-Me aa, followed by solution phase macrocyclisation to afford target cyclo pentapeptide compounds. In the present study, all galaxamide analogues exhibited growth inhibition in A549, A549/DPP, SMMC-7721 and HepG2 cell lines. Compounds 6, 18, and 22 exhibited interesting activities towards all cell line tested, while Compounds 1, 4, 15, and 22 showed strong activity towards SMMC-7221 cell line in the range of 1–2 μg/mL IC50. Flow cytometry experiment revealed that galaxamide analogues namely Compounds 6, 18, and 22 induced concentration dependent SMMC-7721 cell apoptosis after 48 h. These compounds induced G0/G1 phase cell-cycle arrest and morphological changes indicating induction of apoptosis. Thus, findings of our study suggest that the galaxamide and its analogues 6, 18 and 22 exerted growth inhibitory effect on SMMC-7721 cells by arresting the cell cycle in the G0/G1 phase and inducing apoptosis. Compound 1 showed promising anti-tumor activity towards SMMC-7721 cancer cell line, which is 9 and 10 fold higher than galaxamide and reference DPP (cisplatin), respectively. PMID:27598177

  20. Variation of geochemical risk associated with the use of ophiolitic washing mud as refilling material in a basalt quarry of the Northern Apennine (Italy)

    NASA Astrophysics Data System (ADS)

    Voltaggio, M.; Spadoni, M.

    2007-10-01

    Ophiolitic sequences in Northern Apennines are usually exploited as source of raw material for civil engineering works. Grinding procedures of basalts imply the production of dusts with relatively high concentration of PHES. This paper studied the increase of geochemical risk when washing mud produced at Sasso di Castro quarry site (Tuscany) is reused as rock keeper in a near dismissed quarry and highlighted geochemical fractionation produced on the base of different mineral hardness. Co, Cr, Ni and V concentration measured in washing mud were higher than the limits fixed by the Italian law but compatible with background values. The mobility of these four elements during future weathering processes were estimated by considering the element transfer coefficients and assuming weathered rocks and soils as two different natural analogues of the future state of washing mud. The future concentration was estimated by considering the average lifetime of mineral grains calculated through their dissolution rate, molar volume and grain diameter. The variations of geochemical concentrations were used to estimate the percentage increase of the geochemical risk at the displacement place. After 50 years the associated geochemical risk is still considerably lower than the probability to be damaged by a single landslide event.

  1. Effect of in vivo activation of natural killer (NK) cells by a tilorone analogue on the survival of mice injected intravenously with different experimental murine tumours

    PubMed Central

    ALGARRA, I.; GONZÁLEZ, A.; PÉREZ, M.; GAFORIO, J J; GARRIDO, F.

    1996-01-01

    We studied the effect of a tilorone analogue (RMI 10,874DA) and anti-asialo GM1 serum on the survival of BALB/c and C57B1/6 mice after i.v. injections of different syngeneic murine tumour cells. Tumour lines used were different clones from chemically (GR9 wild type, GR9.B9, B7.1.B4, B7.1.B5, B7.2.38), and ultraviolet light (GRUV3)-induced sarcomas; B16 melanoma and LSTRA and YC8 lymphomas. Pretreatment of mice with tilorone inhibited metastatic colonization and increased survival significantly in all cases. In some tumour systems, the effect was attenuated when high numbers of cells were injected. Abrogation of NK cells with anti-asialo GM1 serum significantly decreased (in all tumours and at different cell doses) survival in comparison with untreated mice injected with tumours, regardless of cell dose used. These results clearly suggest that NK cell activation in vivo by the tilorone analogue we tested prolongs survival and inhibits metastasis formation in mice, even when pretreatment consists of a single dose of the analogue. PMID:8608652

  2. The structure activity relationship of discodermolide analogues.

    PubMed

    Shaw, Simon J

    2008-03-01

    The marine polyketide discodermolide is a member of a class of natural products that stabilize microtubules. Many analogues have been synthesized suggesting that few changes can be made to the internal carbon backbone. Both ends of the molecule, however, can be modified. The majority of analogues have been generated via modification of the lactone region. This suggests that significant simplifications can be made in this region provided that the lactone moiety is maintained.

  3. Survey of Analogue Spacetimes

    NASA Astrophysics Data System (ADS)

    Visser, Matt

    Analogue spacetimes (and more boldly, analogue models both of and for gravity), have attracted significant and increasing attention over the last decade and a half. Perhaps the most straightforward physical example, which serves as a template for most of the others, is Bill Unruh's model for a dumb hole,(mute black hole, acoustic black hole), wherein sound is dragged along by a moving fluid—and can even be trapped behind an acoustic horizon. This and related analogue models for curved spacetimes are useful in many ways: analogue spacetimes provide general relativists with extremely concrete physical models to help focus their thinking, and conversely the techniques of curved spacetime can sometimes help improve our understanding of condensed matter and/or optical systems by providing an unexpected and countervailing viewpoint. In this chapter, I shall provide a few simple examples of analogue spacetimes as general background for the rest of the contributions.

  4. Fluid-rock interactions in CO2-saturated, granite-hosted geothermal systems: Implications for natural and engineered systems from geochemical experiments and models

    NASA Astrophysics Data System (ADS)

    Lo Ré, Caroline; Kaszuba, John P.; Moore, Joseph N.; McPherson, Brian J.

    2014-09-01

    Hydrothermal experiments were conducted and geochemical models constructed to evaluate the geochemical and mineralogical response of fractured granite and granite + epidote in contact with thermal water, with and without supercritical CO2, at 250 °C and 25-45 MPa. Illite ± smectite ± zeolite(?) precipitate as secondary minerals at the expense of K-feldspar, oligoclase, and epidote. Illite precipitates in experiments reacting granite and granite + epidote with water; metastable smectite forms in the experiments injected with supercritical CO2. Waters are supersaturated with respect to quartz and saturated with respect to chalcedony in CO2-charged experiments, but neither mineral formed. Carbonate formation is predicted for experiments injected with supercritical CO2, but carbonate only formed during cooling and degassing of the granite + epidote + CO2 experiment. Experimental results provide insight into the buffering capacity of granites as well as the drivers of clay formation. Metastable smectite in the experiments is attributed to high water-rock ratios, high silica activities, and high CO2 and magnesium-iron concentrations. Smectite precipitation in supercritical CO2-bearing geothermal systems may affect reservoir permeability. Silicate formation may create or thicken caps within or on the edges of geothermal reservoirs. Carbonate formation, as desired for carbon sequestration projects coinciding with geothermal systems, may require extended periods of time; cooling and degassing of CO2-saturated waters leads to carbonate precipitation, potentially plugging near-surface production pathways.

  5. Nonstationary analogue black holes

    NASA Astrophysics Data System (ADS)

    Eskin, Gregory

    2014-12-01

    We study the existence of analogue nonstationary spherically symmetric black holes. The prime example is the acoustic model see Unruh (1981 Phys. Rev. Lett. 46 1351). We consider also a more general class of metrics that could be useful in other physical models of analogue black and white holes. We give examples of the appearance of black holes and of disappearance of white holes. We also discuss the relation between the apparent and the event horizons for the case of analogue black holes. In the end we study the inverse problem of determination of black or white holes by boundary measurements for the spherically symmetric nonstationary metrics.

  6. Composition of natural gas and crude oil produced from 10 wells in the Lower Silurian "Clinton" Sandstone, Trumbull County, Ohio: Chapter G.7 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    USGS Publications Warehouse

    Burruss, Robert A.; Ryder, Robert T.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    Natural gases and associated crude oils in the “Clinton” sandstone, Medina Group sandstones, and equivalent Tuscarora Sandstone in the northern Appalachian basin are part of a regional, continuous-type or basin-centered accumulation. The origin of the hydrocarbon charge to regional continuoustype accumulations is poorly understood. We have analyzed the molecular and stable isotopic composition of gases and oils produced from 10 wells in the “Clinton” sandstone in Trumbull County, Ohio, in an initial attempt to identify the characteristics of the accumulated fluids. The analyses show that the fluids have remarkably uniform compositions that are similar to previously published analyses of oils (Cole and others, 1987) and gases (Laughrey and Baldasarre, 1998) in Early Silurian reservoirs elsewhere in Ohio; however, geochemical parameters in the oils and gases suggest that the fluids have experienced higher levels of thermal stress than the present-day burial conditions of the reservoir rocks. The crude oils have an unusual geochemical characteristic: they do not contain detectable levels of sterane and triterpane biomarkers. The origin of these absences is unknown.

  7. A stereodivergent strategy for the preparation of corynantheine and ipecac alkaloids, their epimers, and analogues: efficient total synthesis of (-)-dihydrocorynantheol, (-)-corynantheol, (-)-protoemetinol, (-)-corynantheal, (-)-protoemetine, and related natural and nonnatural compounds.

    PubMed

    Zhang, Wei; Bah, Juho; Wohlfarth, Andreas; Franzén, Johan

    2011-12-01

    Here we present a general and common catalytic asymmetric strategy for the total and formal synthesis of a broad number of optically active natural products from the corynantheine and ipecac alkaloid families, for example, indolo[2,3-a]- and benzo[a]quinolizidines. Construction of the core alkaloid skeletons with the correct absolute and relative stereochemistry relies on an enantioselective and diastereodivergent one-pot cascade sequence followed by an additional diastereodivergent reaction step. This allows for enantio- and diastereoselective synthesis of three out of four possible epimers of the quinolizidine alkaloids that begin from common and easily accessible starting materials by using a common synthetic route. Focus has been made on excluding protecting groups and limiting isolation and purification of synthetic intermediates. This methodology is applied in the total synthesis of the natural products (-)-dihydrocorynantheol, (-)-hirsutinol, (-)-corynantheol, (-)-protometinol, (-)-dihydrocorynantheal, (-)-corynantheal, (-)-protoemetine, (-)-(15S)-hydroxydihydrocorynantheol, and an array of their nonnatural epimers. The potential of this strategy is also demonstrated in the synthesis of biologically interesting natural product analogues not accessible through synthetic elaboration of alkaloid precursors available from nature, for example, thieno[3,2-a]quinolizidine derivatives. We also report the formal synthesis of (+)-dihydrocorynantheine, (-)-emetine, (-)-cephaeline, (-)-tubulosine, and (-)-deoxytubulosine.

  8. Nature of the lowest electron transitions in styryl bases benzothiazole derivatives and analogues bearing para-methoxy and -trifluoromethyl substituents in phenylyne moiety

    NASA Astrophysics Data System (ADS)

    Navozenko, O. M.; Naumenko, A. P.; Yashchuk, V. M.; Bricks, J. L.; Slominskii, Yu. L.; Ryabitskii, A. B.; Kachkovsky, O. D.

    2016-06-01

    Combined quantum-chemical and spectral investigation of cyanine bases derivatives of thiastyryls as well as their analogues with dimethylamino, metoxy and trifluorine-methyl substituents has been fulfilled. The calculations have shown that going from cationic styryl/metoxystyryl to the corresponding neutral bases is accompanied by substantial change of the equilibrium molecular geometry and charge distribution at atoms, while the experimental absorption band undergoes the essential hypsochromic shift. It is established that introducing on the donor groups in the bases causes negligible change of the carbon-carbon bond and atomic charges in the main chromophore, in contrast to the substantial changes of the magnitude and direction state dipole moments in both ground and excited states. It is found that the bases with the donor groups in benzthiazole moiety and with acceptor CF3 substituent demonstrate the inversion of the direction of the dipole moment. Based on the spectral and quantum-chemical study, one has proposed that some widening of the spectral bands is connected with the vibronic interaction, not with the second electron transition.

  9. Analogue Representations of Spatial Objects and Tranformations.

    ERIC Educational Resources Information Center

    Cooper, Lynn A.

    Considerable discussion and debate have been devoted to the extent and nature of structural or functional correspondence between internal representations and their external visual counterparts. An analogue representation or process is one in which the relational structure of external events is preserved in the corresponding internal…

  10. Biodegradable analogues of DDT*

    PubMed Central

    Metcalf, Robert L.; Kapoor, Inder P.; Hirwe, Asha S.

    1971-01-01

    Despite the immense utility of DDT for vector control its usefulness is prejudiced by its stability in the environment and by the low rate at which it can be degraded biologically. Metabolic studies in insects, in mice, and in a model ecosystem with several food chains have shown that DDT analogues with substituent groups readily attacked by multifunction oxidases undergo a substantial degree of biological degradation and do not appear to be stored readily in animal tissues or concentrated in food chains. Detailed metabolic pathways have been worked out and it is clear that comparative biochemistry can be used to develop DDT analogues that are adequately persistent yet biodegradable. A number of new DDT analogues have been evaluated for insecticidal activity against flies and mosquitos and for their potential usefulness as safe, persistent, and biodegradable insecticides. PMID:5315354

  11. Reflectance spectroscopy of natural organic solids, iron sulfides and their mixtures as refractory analogues for Rosetta/VIRTIS' surface composition analysis of 67P/CG

    NASA Astrophysics Data System (ADS)

    Moroz, Lyuba V.; Markus, Kathrin; Arnold, Gabriele; Henckel, Daniela; Kappel, David; Schade, Ulrich; Rousseau, Batiste; Quirico, Eric; Schmitt, Bernard; Capaccioni, Fabrizio; Bockelee-Morvan, Dominique; Filacchione, Gianrico; Érard, Stéphane; Leyrat, Cedric; VIRTIS Team

    2016-10-01

    Analysis of 0.25-5 µm reflectance spectra provided by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) onboard Rosetta orbiter revealed that the surface of 67P/CG is dark from the near-UV to the IR and is enriched in refractory phases such as organic and opaque components. The broadness and complexity of the ubiquitous absorption feature around 3.2 µm suggest a variety of cometary organic constituents. For example, complex hydrocarbons (aliphatic and polycyclic aromatic) can contribute to the feature between 3.3 and 3.5 µm and to the low reflectance of the surface in the visible. Here we present the 0.25-5 µm reflectance spectra of well-characterized terrestrial hydrocarbon materials (solid oil bitumens, coals) and discuss their relevance as spectral analogues for a hydrocarbon part of 67P/CG's complex organics. However, the expected low degree of thermal processing of cometary hydrocarbons (high (H+O+N+S)/C ratios and low carbon aromaticities) suggests high IR reflectance, intense 3.3-3.5 µm absorption bands and steep red IR slopes that are not observed in the VIRTIS spectra. Fine-grained opaque refractory phases (e.g., iron sulfides, Fe-Ni alloys) intimately mixed with other surface components are likely responsible for the low IR reflectance and low intensities of absorption bands in the VIRTIS spectra of the 67P/CG surface. In particular, iron sulfides are common constituents of cometary dust, "cometary" chondritic IDPs, and efficient darkening agents in primitive carbonaceous chondrites. Their effect on reflectance spectra of an intimate mixture is strongly affected by grain size. We report and discuss the 0.25-5 µm reflectance spectra of iron sulfides (meteoritic troilite and several terrestrial pyrrhotites) ground and sieved to various particle sizes. In addition, we present reflectance spectra of several intimate mixtures of powdered iron sulfides and solid oil bitumens. Based on the reported laboratory data, we discuss the ability of

  12. Clinical utility of quantitative HBsAg in natural history and nucleos(t)ide analogue treatment of chronic hepatitis B: new trick of old dog.

    PubMed

    Tseng, Tai-Chung; Kao, Jia-Horng

    2013-01-01

    Using commercial quantitative assays, quantitative hepatitis B surface antigen (qHBsAg) has improved our understanding and management of chronic hepatitis B (CHB). The HBsAg level is highest in the immune tolerance phase, starts to decline during the immune clearance phase, and decreases slowly but progressively after hepatitis B e antigen (HBeAg) seroconversion. The HBsAg level is lowest in individuals with an inactive carrier state but higher in those who develop HBeAg-negative hepatitis. It has been shown that a reduction of HBsAg by 1 log IU/mL or more reflects improved host immune control of HBV infection. A combination of HBsAg <1000 IU/mL and HBV-DNA <2000 IU/mL can identify a 3-year inactive state in a genotype D HBeAg-negative carrier population. In the Asian-Pacific region, where HBV genotypes B and C are dominant, HBsAg levels of ≤10-100 IU/mL predict HBsAg loss over time. As to the prediction of disease progression, low-viremic carriers with HBsAg >1000 IU/mL have been shown to be at higher risks of HBeAg-negative hepatitis, cirrhosis, and hepatocellular carcinoma than those with HBsAg <1000 IU/mL. Although qHBsAg has been widely used in CHB patients receiving pegylated interferon therapy, the HBsAg decline is slow and does not correlate with HBV-DNA levels during nucleos(t)ide analogue (NUC) therapy. However, a rapid HBsAg decline during NUC therapy may identify patients who will finally clear HBsAg. A 6- to 12-monthly assessment of HBsAg level could be considered during NUC therapy. Taking these lines of evidence together, qHBsAg can complement HBV-DNA levels to optimize the management of CHB patients in our daily clinical practice.

  13. Dolastatin 11 conformations, analogues and pharmacophore.

    PubMed

    Ali, Md Ahad; Bates, Robert B; Crane, Zackary D; Dicus, Christopher W; Gramme, Michelle R; Hamel, Ernest; Marcischak, Jacob; Martinez, David S; McClure, Kelly J; Nakkiew, Pichaya; Pettit, George R; Stessman, Chad C; Sufi, Bilal A; Yarick, Gayle V

    2005-07-01

    Twenty analogues of the natural antitumor agent dolastatin 11, including majusculamide C, were synthesized and tested for cytotoxicity against human cancer cells and stimulation of actin polymerization. Only analogues containing the 30-membered ring were active. Molecular modeling and NMR evidence showed the low-energy conformations. The amide bonds are all trans except for the one between the Tyr and Val units, which is cis. Since an analogue restricted to negative 2-3-4-5 angles stimulated actin polymerization but was inactive in cells, the binding conformation (most likely the lowest-energy conformation in water) has a negative 2-3-4-5 angle, whereas a conformation with a positive 2-3-4-5 angle (most likely the lowest energy conformation in chloroform) goes through cell walls. The highly active R alcohol from borohydride reduction of dolastatin 11 is a candidate for conversion to prodrugs.

  14. Open geochemical database

    NASA Astrophysics Data System (ADS)

    Zhilin, Denis; Ilyin, Vladimir; Bashev, Anton

    2010-05-01

    We regard "geochemical data" as data on chemical parameters of the environment, linked with the geographical position of the corresponding point. Boosting development of global positioning system (GPS) and measuring instruments allows fast collecting of huge amounts of geochemical data. Presently they are published in scientific journals in text format, that hampers searching for information about particular places and meta-analysis of the data, collected by different researchers. Part of the information is never published. To make the data available and easy to find, it seems reasonable to elaborate an open database of geochemical information, accessible via Internet. It also seems reasonable to link the data with maps or space images, for example, from GoogleEarth service. For this purpose an open geochemical database is being elaborating (http://maps.sch192.ru). Any user after registration can upload geochemical data (position, type of parameter and value of the parameter) and edit them. Every user (including unregistered) can (a) extract the values of parameters, fulfilling desired conditions and (b) see the points, linked to GoogleEarth space image, colored according to a value of selected parameter. Then he can treat extracted values any way he likes. There are the following data types in the database: authors, points, seasons and parameters. Author is a person, who publishes the data. Every author can declare his own profile. A point is characterized by its geographical position and type of the object (i.e. river, lake etc). Value of parameters are linked to a point, an author and a season, when they were obtained. A user can choose a parameter to place on GoogleEarth space image and a scale to color the points on the image according to the value of a parameter. Currently (December, 2009) the database is under construction, but several functions (uploading data on pH and electrical conductivity and placing colored points onto GoogleEarth space image) are

  15. Geochemical Interpretation of Collision Volcanism

    NASA Astrophysics Data System (ADS)

    Pearce, Julian

    2014-05-01

    collision type with extreme LILE and significant HFSE enrichment relative to MORB and with large negative Nb-Ta and Ti anomalies. Post-collision volcanism is usually ascribed to combinations of slab detachment, delamination, and slab roll back (orogenic) and extension (post-orogenic). The magma source is typically conductively-heated, sub-continental mantle lithosphere with composition and depth of melting depending on the nature and evolution of the collision zone in question. Geochemical patterns may be similar to those of syn-collision basalts or of intraplate, continental basalts - or transitional between these. This variability in space and time, though problematic for geochemical fingerprinting, can give clues to the polarity and development of the collision zone, for example by highlighting the distribution of subduction-modified mantle lithosphere and hence of pre-collision subduction zones. One characteristic common to this setting is a high crustal input resulting from the presence of a hot, thick 'crustal chemical filter' which is evident on geochemical projections that highlight AFC-type processes. Using this, and other, geochemical features it is possible to develop methodologies to at least partly see through the complexity of collision terranes.

  16. Initiation of rubber biosynthesis: in vitro comparisons of benzophenone-modified diphosphate analogue structure in three natural rubber-producing species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural rubber is synthesized by initiation with one allylic pyrophosphate (APPs) molecule followed by elongation with thousands of isopentenyl pyrophosphate (IPP) molecules by the enzyme rubber transferase (a cis-prenyl transferase). To better understand how rubber transferase initiates and binds A...

  17. Developing a robust geochemical and reactive transport model to evaluate possible sources of arsenic at the CO[subscript 2] sequestration natural analog site in Chimayo, New Mexico

    SciTech Connect

    Viswanathan, Hari; Dai, Zhenxue; Lopano, Christina; Keating, Elizabeth; Hakala, J. Alexandra; Scheckel, Kirk G.; Zheng, Liange; Gutherie, George D.; Pawar, Rajesh

    2012-10-24

    Migration of carbon dioxide (CO{sub 2}) from deep storage formations into shallow drinking water aquifers is a possible system failure related to geologic CO{sub 2} sequestration. A CO{sub 2} leak may cause mineral precipitation/dissolution reactions, changes in aqueous speciation, and alteration of pH and redox conditions leading to potential increases of trace metal concentrations above EPA National Primary Drinking Water Standards. In this study, the Chimayo site (NM) was examined for site-specific impacts of shallow groundwater interacting with CO{sub 2} from deep storage formations. Major ion and trace element chemistry for the site have been previously studied. This work focuses on arsenic (As), which is regulated by the EPA under the Safe Drinking Water Act and for which some wells in the Chimayo area have concentrations higher than the maximum contaminant level (MCL). Statistical analysis of the existing Chimayo groundwater data indicates that As is strongly correlated with trace metals U and Pb indicating that their source may be from the same deep subsurface water. Batch experiments and materials characterization, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), and synchrotron micro X-ray fluorescence ({mu}-XRF), were used to identify As association with Fe-rich phases, such as clays or oxides, in the Chimayo sediments as the major factor controlling As fate in the subsurface. Batch laboratory experiments with Chimayo sediments and groundwater show that pH decreases as CO{sub 2} is introduced into the system and buffered by calcite. The introduction of CO{sub 2} causes an immediate increase in As solution concentration, which then decreases over time. A geochemical model was developed to simulate these batch experiments and successfully predicted the pH drop once CO{sub 2} was introduced into the experiment. In the model, sorption of As to illite, kaolinite and smectite through surface complexation proved to be the key reactions in

  18. Thermodynamic Data for Geochemical Modeling of Carbonate Reactions Associated with CO2 Sequestration – Literature Review

    SciTech Connect

    Krupka, Kenneth M.; Cantrell, Kirk J.; McGrail, B. Peter

    2010-09-01

    Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ΔfG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than

  19. Geochemical assessment of nuclear waste isolation. Report of activities during fiscal year 1982

    SciTech Connect

    Not Available

    1983-07-01

    The status of the following investigations is reported: canister/overpack-backfill chemical interactions and mechanisms; backfill and near-field host rock chemical interactions mechanisms; far-field host rock geochemical interactions; verification and improvement of predictive algorithms for radionuclide migration; and geologic systems as analogues for long-term radioactive waste isolation.

  20. Geochemical modeling: a review

    SciTech Connect

    Jenne, E.A.

    1981-06-01

    Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted.

  1. Aspartame and Its Analogues

    NASA Astrophysics Data System (ADS)

    Pavlova, L. A.; Komarova, T. V.; Davidovich, Yurii A.; Rogozhin, S. V.

    1981-04-01

    The results of studies on the biochemistry of the sweet taste are briefly reviewed. The methods of synthesis of "aspartame" — a sweet dipeptide — are considered, its structural analogues are described, and quantitative estimates are made of the degree of sweetness relative to sucrose. Attention is concentrated mainly on problems of the relation between the structure of the substance and its taste in the series of aspartyl derivatives. The bibliography includes 118 references.

  2. Quantum analogue computing.

    PubMed

    Kendon, Vivien M; Nemoto, Kae; Munro, William J

    2010-08-13

    We briefly review what a quantum computer is, what it promises to do for us and why it is so hard to build one. Among the first applications anticipated to bear fruit is the quantum simulation of quantum systems. While most quantum computation is an extension of classical digital computation, quantum simulation differs fundamentally in how the data are encoded in the quantum computer. To perform a quantum simulation, the Hilbert space of the system to be simulated is mapped directly onto the Hilbert space of the (logical) qubits in the quantum computer. This type of direct correspondence is how data are encoded in a classical analogue computer. There is no binary encoding, and increasing precision becomes exponentially costly: an extra bit of precision doubles the size of the computer. This has important consequences for both the precision and error-correction requirements of quantum simulation, and significant open questions remain about its practicality. It also means that the quantum version of analogue computers, continuous-variable quantum computers, becomes an equally efficient architecture for quantum simulation. Lessons from past use of classical analogue computers can help us to build better quantum simulators in future.

  3. Preliminary petrological and geochemical results from the Salton Sea Geothermal Field, California: A near-field natural analog of a radioactive waste repository in salt: Topical report No. 2

    SciTech Connect

    Elders, W.A.; Cohen, L.H.; Williams, A.E.; Neville, S.; Collier, P.; Oakes, C.

    1986-03-01

    High concentrations of radionuclides and high temperatures are not naturally encountered in salt beds. For this reason, the Salton Sea Geothermal Field (SSGF) may be the best available geologic analog of some of the processes expected to occur in high level nuclear waste repositories in salt. Subsurface temperatures and brine concentrations in the SSGF span most of the temperature range and fluid inclusion brine range expected in a salt repository, and the clay-rich sedimentary rocks are similar to those which host bedded or domal salts. As many of the chemical processes observed in the SSGF are similar to those expected to occur in or near a salt repository, data derived from it can be used in the validation of geochemical models of the near-field of a repository in salt. This report describes preliminary data on petrology and geochemistry, emphasizing the distribution of rare earth elements and U and Th, of cores and cuttings from several deep wells chosen to span a range of temperature gradients and salinities. Subsurface temperature logs have been augmented by fluid inclusion studies, to reveal the effects of brines of varying temperature and salinity. The presence of brines with different oxygen isotopic signatures also indicate lack of mixing. Whole rock major, minor and trace element analyses and data on brine compositions are being used to study chemical migration in these sediments. 65 refs., 20 figs., 3 tabs.

  4. Isotopic evidence for the retention of Sr-90 inferred from excess Zr-90 in the Oklo natural fission reactors: Implication for geochemical behaviour of fissiogenic Rb, Sr, Cs and Ba

    NASA Astrophysics Data System (ADS)

    Hidaka, Hiroshi; Sugiyama, Takeshi; Ebihara, Mitsuru; Holliger, Philippe

    1994-03-01

    In order to investigate the mobility of fissiogenic Sr-90 in the geological environment, the Zr isotopic compositions of seven samples from one of the newly formed Oklo natural reactor zones (i.e., reactor core and adjacent rocks (10, SF84)) in the Republic of Gabon were determined with an inductively coupled plasma mass spectrometer (ICP-MS). Zr isotopes in uraninite grains from different reactor zones were also measured by secondary ion mass spectrometry (SIMS). Fissiogenic Zr isotopic abundances of three samples from the reactor core have excess Zr-90, which has never before been formed in previous Oklo samples. In this paper, the geochemical behaviour of Zr-90 is discussed by making use of the relative retentivity inferred from the isotopic abundance of Sr. The excess in Zr-90 suggests dependence on the degree of retention/migration of Sr-90, the precursor of Zr-90 in the fission chain. In the aqueous phase, chemical fractionation between Sr and Zr could have occurred before radioactive Sr-90 decayed. Considering the halflife of Sr-90 (t(sub 1/2) = 29.1 y), considerable amounts of the latter have been produced during criticality. Sr and Zr (including Zr-90) could have been redistributed between the reactor core and its vicinity. The retentivity of fissiogenic Zr-90 in reactor core 10 is not homogeneous. In addition, the distributions of Rb, Cs and Ba is also heterogeneous.

  5. Iodine and selenium in natural water, their fixation on geochemical barriers in soils and rocks and explanation of I and Se behavior in water-solid phase system using thermodynamic modeling

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Ryzhenko, Boris; Cherkasova, Elena; Sedykh, Ivelina; Korsakova, Nadezhda; Berezkin, Victor; Kolmykova, Lyudmila; Danilova, Valentina; Khushvakhtova, Sabzbakhor

    2014-05-01

    Iodine and selenium are essential for normal functioning of thyroid gland. Their natural deficiency in areas subjected to radioiodine contamination during nuclear tests and accidents may increase the risk of thyroid cancer among the most sensitive groups of population. Deficiency is caused by both the low abundance of microelements in the environmental components of the local food chain and their fixation on geochemical barriers due to such processes as chemical transformation, sorption, chemisorption, complexing. The studies of iodine and selenium distribution in soils, herbs and drinking water in rural settlements of the Bryansk oblast' confirmed low level of iodine and selenium content in local soils, plants and water and revealed different character of their distribution in soils and waters formed in geochemically different conditions of water migration in areas of fluvioglacial, moraine and loess-like soil forming rocks (the polesje, moraine and opolje landscapes correspondingly). Iodine content in top horizons of the soils developed on loess-like sediments and rich in organic matter was considerably higher as compared to those formed on sandy moraine or fluvioglacial sediments. For selenium the difference was not pronounced. Iodine was noted for positive correlation with Corg and fixation in the soil profile on carbonate barrier. A negative correlation was found between selenium content in grasses and in topsoil of subordinated elementary landscapes characterized by waterlogged and reduction conditions in soils. Thermodynamic modeling performed for 47 water samples on the basis of their chemical composition helped to explain the established patterns of iodine and selenium behavior in soil-water system. It demonstrated the possibility of existence of CaI+ and MgI+ complexes in water and sedimentation of FeSe(cr) in presence of a considerable amount of Fe2+. Iodine complexation with Ca and Mg ions may explain its further fixation on carbonate barrier in soils

  6. Confocal {mu}-XRF, {mu}-XAFS, and {mu}-XRD Studies of Sediment from a Nuclear Waste Disposal Natural Analogue Site and Fractured Granite Following a Radiotracer Migration Experiment

    SciTech Connect

    Denecke, Melissa A.; Brendebach, Boris; Rothe, Joerg; Simon, Rolf; Janssens, Koen; Nolf, Wout de; Vekemans, Bart; Falkenberg, Gerald; Somogyi, Andrea; Noseck, Ulrich

    2007-02-02

    Combined {mu}-XRF, {mu}-XAFS, and {mu}-XRD investigations of a uranium-rich tertiary sediment, from a nuclear repository natural analogue site, and a fractured granite bore core section after a column tracer experiment using a Np(V) containing cocktail have been performed. Most {mu}-XRF/{mu}-XAFS measurements are recorded in a confocal geometry to provide added depth information. The U-rich sediment results show uranium to be present as a tetravalent phosphate and that U(IV) is associated with As(V). Arsenic present is either As(V) or As(0). The As(0) forms thin coatings on the surface of pyrite nodules. A hypothesis for the mechanism of uranium immobilization is proposed, where arsenopyrite acted as reductant of ground water dissolved U(VI) leading to precipitation of less soluble U(IV) and thereby forming As(V). Results for the granite sample show the immobilized Np to be tetravalent and associated with facture material.

  7. Geochemical Trends and Natural Attenuation of RDX, Nitrate, and Perchlorate in the Hazardous Test Area Fractured-Granite Aquifer, White Sands Missile Range, New Mexico, 1996-2006

    USGS Publications Warehouse

    Langman, Jeff B.; Robertson, Andrew J.; Bynum, Jamar; Gebhardt, Fredrick E.

    2008-01-01

    A fractured-granite aquifer at White Sands Missile Range is contaminated with the explosive compound RDX, nitrate, and perchlorate (oxidizer associated with rocket propellant) from the previous use of the Open Burn/Open Detonation site at the Hazardous Test Area. RDX, nitrate, and perchlorate ground-water concentrations were analyzed to examine source characteristics, spatial and temporal variability, and the influence of the natural attenuation processes of dilution and degradation in the Hazardous Test Area fractured-granite aquifer. Two transects of ground-water wells from the existing monitoring-site network - one perpendicular to ground-water flow (transect A-A') and another parallel to ground-water flow (transect B-B') - were selected to examine source characteristics and the spatial and temporal variability of the contaminant concentrations. Ground-water samples collected in 2005 from a larger sampling of monitoring sites than the two transects were analyzed for various tracers including major ions, trace elements, RDX degradates, dissolved gases, water isotopes, nitrate isotopes, and sulfate isotopes to examine the natural attenuation processes of dilution and degradation. Recharge entrains contaminants at the site and transports them downgradient towards the Tularosa Basin floor through a poorly connected fracture system(s). From 1996 to 2006, RDX, nitrate, and perchlorate concentrations in ground water downgradient from the Open Burn/Open Detonation site have been relatively stable. RDX, nitrate, and perchlorate in ground water from wells near the site indicate dispersed contaminant sources in and near the Open Burn/Open Detonation pits. The sources of RDX and nitrate in the pit area have shifted with time, and the shift correlates with the regrading of the south and east berms of each pit in 2002 and 2003 following closure of the site. The largest RDX concentrations were in ground water about 0.1 mile downgradient from the pits, the largest perchlorate

  8. Anorogenic nature of magmatism in the Northern Baikal volcanic belt: Evidence from geochemical, geochronological (U-Pb), and isotopic (Pb, Nd) data

    USGS Publications Warehouse

    Neymark, L.A.; Larin, A.M.; Nemchin, A.A.; Ovchinnikova, G.V.; Rytsk, E. Yu

    1998-01-01

    The Northern Baikal volcanic belt has an age of 1.82-1.87 Ga and extends along the boundary between the Siberian Platform and the Baikal foldbelt. The volcanic belt is composed of volcanics of the Akitkan Group and granitic rocks of the Irel and Primorsk complexes. The geochemistry of the rocks points to the intraplate anorogenic nature of the belt. U-Pb zircon dating of the Chuya granitoids revealed that they are older (2020-2060 Ma) than the Northern Baikal volcanic belt and, thus, cannot be regarded as its component. Data on the Pb isotopic system of feldspars from the granitoids confirm the contemporaneity of all volcanic rocks of the belt except the volcanics of the upper portion of the Akitkan Group (Chaya Formation). Our data suggest its possibly younger (???1.3 Ga) age. The isotopic Nd and Pb compositions of the acid volcanic rocks provide evidence of the heterogeneity of their crustal protoliths. The volcanics of the Malaya Kosa Formation have ??Nd(T) = -6.1, ??2 = 9.36, and were most probably produced with the participation of the U-depleted lower continental crust of Archean age. Other rocks of the complex show ??Nd(T) from -0.1 to -2.4, ??2 = 9.78, and could have been formed by the recycling of the juvenile crust. The depletion of the Malaya Kosa volcanics in most LILEs and HFSEs compared with other acid igneous rocks of the belt possibly reflects compositional differences between the Late Archean and Early Proterozoic crustal sources. The basaltic rocks of the Malaya Kosa Formation (??Nd varies from -4.6 to -5.4) were produced by either the melting of the enriched lithospheric mantle or the contamination of derivatives of the depleted mantle by Early Archean lower crustal rocks, which are not exposed within the area. Copyright ?? 1998 by MAEe Cyrillic signK Hay??a/Interperiodica Publishing.

  9. Petrogenesis of carbonated meta-ultramafic lenses from the Neoproterozoic Heiani ophiolite, South Eastern Desert, Egypt: A natural analogue to CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Gahlan, Hisham A.; Arai, Shoji; Almadani, Sattam A.

    2015-02-01

    Among a set of peculiar meta-ultramafics, carbonate-orthopyroxenites are observed for the first time in the Heiani ophiolite belt, South Eastern Desert, Egypt. They form massive lensoidal masses up to 50 m long and 20 m wide. The lenses show a marked structural concordance with their neighboring country rocks. The typical country rocks are represented by the following high-grade metamorphic rocks: kyanite-muscovite schists, amphibolites, kyanite-bearing biotite gneisses, migmatites, granite gneisses and mobilizates. The studied carbonate-orthopyroxenites consist mainly of metamorphic orthopyroxene + magnesite, among other metamorphic, relict primary and retrograde secondary minerals. According to primary chromian spinel (Cr#, 0.7-0.84) chemistry and morphology, absence of clinopyroxene and presence of primary mantle olivine (Fo89-91) as relicts in the metamorphic orthopyroxene, the Heiani carbonate-orthopyroxenites seem to have formed from a highly depleted mantle peridotite precursor. At a late collisional stage during the Pan-Africa terrane accretion and the E-W crustal shortening (ca. 650-620 Ma), high-grade (upper amphibolite facies) low-P/high-T regional metamorphism (ca. 660 Ma) accompanied by CO2-metasomatism resulted in formation of the Heiani carbonate-orthopyroxenites. Mostly the carbonate-bearing shelf sediments beneath and/or in juxtaposition with the Heiani ophiolite are considered to be the proven source of the CO2-rich fluids. Although, a mixed sedimentary-mantle C source is not unlikely. A mineral paragenetic correlation with experimental data for the system MgO-SiO2-H2O-CO2 suggests metamorphic conditions consistent with those of the high-grade country rocks; i.e. 630-650 °C, 6-7 kbar (20-23 km depth) and high-XCO2 (0.6-0.7). The CO2-bearing fluids discharging along faults gave rise to regionally widespread carbonate-bearing assemblages. Accordingly, the Heiani carbonate-orthopyroxenites are considered the by-products of natural carbon

  10. Analogues of thiolactomycin as potential antimalarial agents.

    PubMed

    Jones, Simon M; Urch, Jonathan E; Kaiser, Marcel; Brun, Reto; Harwood, John L; Berry, Colin; Gilbert, Ian H

    2005-09-22

    Analogues of the natural antibiotic thiolactomycin (TLM), an inhibitor of the condensing reactions of type II fatty acid synthase, were synthesized and evaluated for their ability to inhibit the growth of the malaria parasite Plasmodium falciparum. Alkylation of the C4 hydroxyl group led to the most significant increase in growth inhibition (over a 100-fold increase in activity compared to TLM). To investigate the mode of action, the P. falciparum KASIII enzyme was produced for inhibitor assay. A number of TLM derivatives were identified that showed improved inhibition of this enzyme compared to TLM. Structure-activity relationships for enzyme inhibition were identified for some series of TLM analogues, and these also showed weak correlation with inhibition of parasite growth, but this did not hold for other series. On the basis of the lack of a clear correlation between inhibition of pfKASIII activity and parasite growth, we conclude that pfKASIII is not the primary target of TLM analogues. Some of the analogues also inhibited the growth of the parasitic protozoa Trypanosoma cruzi, T. brucei, and Leishmania donovani.

  11. The IUGS/IAGC Task Group on Global Geochemical Baselines

    USGS Publications Warehouse

    Smith, David B.; Wang, Xueqiu; Reeder, Shaun; Demetriades, Alecos

    2012-01-01

    The Task Group on Global Geochemical Baselines, operating under the auspices of both the International Union of Geological Sciences (IUGS) and the International Association of Geochemistry (IAGC), has the long-term goal of establishing a global geochemical database to document the concentration and distribution of chemical elements in the Earth’s surface or near-surface environment. The database and accompanying element distribution maps represent a geochemical baseline against which future human-induced or natural changes to the chemistry of the land surface may be recognized and quantified. In order to accomplish this long-term goal, the activities of the Task Group include: (1) developing partnerships with countries conducting broad-scale geochemical mapping studies; (2) providing consultation and training in the form of workshops and short courses; (3) organizing periodic international symposia to foster communication among the geochemical mapping community; (4) developing criteria for certifying those projects whose data are acceptable in a global geochemical database; (5) acting as a repository for data collected by those projects meeting the criteria for standardization; (6) preparing complete metadata for the certified projects; and (7) preparing, ultimately, a global geochemical database. This paper summarizes the history and accomplishments of the Task Group since its first predecessor project was established in 1988.

  12. Analogue-to-Digital and Digital-to-Analogue Conversion.

    ERIC Educational Resources Information Center

    Gregory, Martin

    1997-01-01

    Discusses circuits for three-bit and four-bit analogue digital converters and digital analogue converters. These circuits feature slow operating speeds that enable the circuitry to be used to demonstrate the mode of operation using oscilloscopes and signal generators. (DDR)

  13. Crystal chemistry of a Ba-dominant analogue of hydrodelhayelite and natural ion-exchange transformations in double- and triple-layer phyllosilicates in post-volcanic systems of the Eifel region, Germany

    NASA Astrophysics Data System (ADS)

    Zubkova, N. V.; Chukanov, N. V.; Pekov, I. V.; Turchkova, A. G.; Lykova, I. S.; Schüller, W.; Ternes, B.; Pushcharovsky, D. Yu.

    2016-03-01

    A Ba-dominant (Ba > K) analogue of hydrodelhayelite (BDAH) from Löhley (Eifel Mts., Rhineland-Palatinate, Germany) and Ba-enriched varieties of related double- and triple-layer phyllosilicates from Eifel are studied. The crystal structure of BDAH was solved by direct methods and refined to R = 0.0698 [1483 unique reflections with I > 2σ(I)]. It is orthorhombic, Pmmn, a = 23.9532(9), b = 7.0522(3), c = 6.6064(3) Å, V = 1115.97(8) Å3, Z = 2. The structure is based upon delhayelite-type double-layer tetrahedral blocks [(Al,Si)4Si12O34(OH,O)4] connected by chains of (Ca,Fe)-centered octahedra. Ba2+ and subordinate K+ occur at partially vacant sites in zeolitic channels within the tetrahedral blocks. The crystal-chemical formula of BDAH is: (Ba0.42K0.34□0.24)(Ca0.88Fe0.12)2(□0.90Mg0.10)2[Si6(Al0.5Si0.5)2O17(OH0.71O0.29)2]ṡ6H2O. The formation of BDAH and Ba-rich varieties of altered delhayelite/fivegite, günterblassite and hillesheimite is considered as a result of leaching of Na, Cl, F and, partially, K and Ca accompanied with hydration and the capture of Ba as a result of natural ion exchange. These minerals are structurally a "bridge" between single-layer phyllosilicates and zeolites having the open three-dimensional tetrahedral Al-Si-O frameworks.

  14. Concerning evaluation of eco-geochemical background in remediation strategy

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Romanov, Sergey

    2015-04-01

    The geochemical concept of biosphere developed by V.I. Vernadsky states the geological role of the living organisms in the course of their active chemical interaction with the inert matter (Vernadsky, 1926, 1960). Basing on this theory it is reasonable to suggest that coevolution of living organisms and their environment led to development of the dynamically stable biogeocenoses precisely adequate to their geochemical environment. Soil cover was treated by V.I. Vernadsky as a balanced bio-inert matter resulting from this interaction. Appearance of human mind and then a civilization led to global expansion of human beings, first able to survive in unfavorable geochemical conditions and then starting chemical transformation of the environment to satisfy the growing demands of mankind in food and energy. The residence in unfavorable environment and local contamination was followed by appearance of endemic diseases of plants, animals and man. Therefore zonal, regional and local chemical composition of the soil cover formed in natural conditions may be used for estimation of the optimum geochemical background, most adequate for the corresponding zonal biogeocenoses and species. Moreover, the natural geochemical background and technogenic fields have unequal spatial structure and this facilitates their identification that may be relatively easy realized in remediation strategy. On the assumption of the foregoing, the adequate methodical approach to remediation of technogenically affected areas should account of the interaction of the existing natural and the newly formed technogenic geochemical fields and include the following steps: 1) the study and mapping of geochemical structure of the natural geochemical background basing on soil maps; 2) the study of contaminants and mapping spatial distribution of technogenic releases; 3) construction of risk maps for the target risk groups with due regard to natural ecological threshold concentration in context of risk degree for

  15. Global geochemical problems

    NASA Technical Reports Server (NTRS)

    Harriss, R. C.

    1980-01-01

    Application of remote sensing techniques to the solution of geochemical problems is considered with emphasis on the 'carbon-cycle'. The problem of carbon dioxide sinks and the areal extent of coral reefs are treated. In order to assess the problems cited it is suggested that remote sensing techniques be utilized to: (1)monitor globally the carbonate and bicarbonate concentrations in surface waters of the world ocean; (2)monitor the freshwater and oceanic biomass and associated dissolved organic carbon; (3) inventory the coral reef areas and types and the associated oceanographic climatic conditions; and (4)measure the heavy metal fluxes from forested and vegetated areas, from volcanos, from different types of crustal rocks, from soils, and from sea surfaces.

  16. Geochemical Speciation Mass Transfer

    1985-12-01

    PHREEQC is designed to model geochemical reactions. Based on an ion association aqueous model, PHREEQC can calculate pH, redox potential, and mass transfer as a function of reaction progress. It can be used to describe geochemical processes for both far-field and near-field performance assessment and to evaluate data acquisition needs and test data. It can also calculate the composition of solutions in equilibrium with multiple phases. The data base, including elements, aqueous species, and mineralmore » phases, is independent of the program and is completely user-definable. PHREEQC requires thermodynamic data for each solid, gaseous, or dissolved chemical species being modeled. The two data bases, PREPHR and DEQPAK7, supplied with PHREEQC are for testing purposes only and should not be applied to real problems without first being carefully examined. The conceptual model embodied in PHREEQC is the ion-association model of Pearson and Noronha. In this model a set of mass action equations are established for each ion pair (and controlling solid phases when making mass transfer calculations) along with a set of mass balance equations for each element considered. These sets of equations are coupled using activity coefficient values for each aqueous species and solved using a continued fraction approach for the mass balances combined with a modified Newton-Raphson technique for all other equations. The activity coefficient expressions in PHREEQC include the extended Debye-Huckel, WATEQ Debye-Huckel, and Davies equations from the original United States Geological Survey version of the program. The auxiliary preprocessor program PHTL, which is derived from EQTL, converts EQ3/6 thermodynamic data to PHREEQC format so that the two programs can be compared. PHREEQC can be used to determine solubility limits on the radionuclides present in the waste form. These solubility constraints may be input to the WAPPA leach model.« less

  17. [Microbial geochemical calcium cycle].

    PubMed

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  18. Mammary Analogue Secretory Carcinoma.

    PubMed

    Stevens, Todd M; Parekh, Vishwas

    2016-09-01

    Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumor that shares the same histologic appearance and ETV6 gene (12p13) rearrangement as secretory carcinoma of the breast. Prior to its recognition, MASC cases were commonly labeled acinic cell carcinoma and adenocarcinoma, not otherwise specified. Despite distinctive histologic features, MASC may be difficult to distinguish from other salivary gland tumors, in particular zymogen-poor acinic cell carcinoma and low-grade salivary duct carcinoma. Although characteristic morphologic and immunohistochemical features form the basis of a diagnosis of MASC, the presence of an ETV6-NTRK3 gene fusion is confirmatory. Given its recent recognition the true prognostic import of MASC is not yet clearly defined. PMID:27575269

  19. Synthesis and biological evaluation of hydrazidomycin analogues.

    PubMed

    Meyer, Florian; Ueberschaar, Nico; Dahse, Hans-Martin; Hertweck, Christian

    2013-11-15

    Hydrazidomycin A is an unusual secondary metabolite of Streptomyces atratus that features a rare enehydrazide core. To learn more about structure-activity relationships of the reported cytotoxic and antiproliferative agent several synthetic routes were explored to synthesize a variety of hydrazidomycin derivatives. Specifically, the size of the side chains, the nature of the double bond and the polar head group were altered. Overall, fourteen analogues were tested for their cytotoxic and antiproliferative effects. Re-examination of synthetic hydrazidomycin A suggests that the antiproliferative activity is attributed to a yet unknown compound that results from degradation or rearrangement. Several of the less complex analogues, however, show antiproliferative activities against individual cancer cell lines and turned out to be more potent than hydrazidomycin A.

  20. Radionuclide migration at the Koongarra uranium deposit, Northern Australia Lessons from the Alligator Rivers analogue project

    NASA Astrophysics Data System (ADS)

    Payne, Timothy E.; Airey, Peter L.

    The Koongarra uranium deposit in Northern Australia provides a ‘natural analogue’ for processes that are of relevance for assessing the safety of radioactive waste disposal. In an international project extending over two decades, the Koongarra ore body was studied to increase the understanding of radionuclide migration and retention mechanisms that might occur in the vicinity of a geological repository. The research effort included extensive characterisation of the geological, hydrological and geochemical conditions at the site. Patterns of the distribution of radionuclides (predominantly members of the 238U decay chain, but also the rare isotopes 239Pu, 99Tc and 129I) were studied in both solid and groundwater phases. The project included detailed studies of uranium adsorption on mineral surfaces, and of subsequent processes that may lead to long-term uranium immobilisation. Numerous models for uranium migration were developed during the project. This paper provides a comprehensive review of the research at Koongarra, and assesses the value of the site for integrating the results of a complex series of laboratory, modelling and field studies. The insights gained from this review of the Koongarra project may assist in maximising the potential scientific benefit of future natural analogue studies.

  1. Analogue Missions on Earth, a New Approach to Prepare Future Missions on the Moon

    NASA Astrophysics Data System (ADS)

    Lebeuf, Martin

    Human exploration of the Moon is a target by 2020 with an initial lunar outpost planned in polar regions. Current architectures maintain a capability for sorties to other latitudes for science activities. In the early stages of design of lunar outpost infrastructure and science activity planning, it has been recognized that analogue missions could play a major role in Moon mission design. Analogue missions, as high fidelity simulations of human and robotic surface operations, can help field scientists and engineers develop and test strategies as well as user requirements, as they provide opportunities to groundtruth measurements, and for the team to share understanding of key science needs and key engineering trades. These types of missions also provide direct training in planning science operations, and in team building and communication. The Canadian Space Agency's Exploration Core Program targets the development of technology infrastructure elements in key areas of science, technology and robotics in preparation for its role in the future exploration of the Moon and Mars. Within this Program, Analogue Missions specifically target the operations requirements and lessons learned that will reduce costs and lower the risk of planetary surface missions. Analogue missions are simulations of planetary surface operations that take place at analogue sites on Earth. A terrestrial analogue site resembles in some key way: eg. geomorphologically or geochemically, a surface environment of another planet. An analogue mission can, therefore, be defined as an integrated set of activities that represent (or simulate) entire mission designs or narrowly focus on specific aspects of planned or potential future planetary exploration missions. Within the CSA's Exploration Core Program, Analogue Missions facilitate the maturation of science instruments and mission concepts by integrating ongoing space instrument and technology development programs with science and analogue elements. As

  2. NASA/ESMD Analogue Mission Plans

    NASA Technical Reports Server (NTRS)

    Hoffman, Stephen J.

    2007-01-01

    A viewgraph presentation exploring Earth and its analogues is shown. The topics include: 1) ESMD Goals for the Use of Earth Analogues; 2) Stakeholders Summary; 3) Issues with Current Analogue Situation; 4) Current state of Analogues; 5) External Implementation Plan (Second Step); 6) Recent Progress in Utilizing Analogues; 7) Website Layout Example-Home Page; 8) Website Layout Example-Analogue Site; 9) Website Layout Example-Analogue Mission; 10) Objectives of ARDIG Analog Initiatives; 11) Future Plans; 12) Example: Cold-Trap Sample Return; 13) Example: Site Characterization Matrix; 14) Integrated Analogue Studies-Prerequisites for Human Exploration; and 15) Rating Scale Definitions.

  3. Collected radiochemical and geochemical procedures

    SciTech Connect

    Kleinberg, J

    1990-05-01

    This revision of LA-1721, 4th Ed., Collected Radiochemical Procedures, reflects the activities of two groups in the Isotope and Nuclear Chemistry Division of the Los Alamos National Laboratory: INC-11, Nuclear and radiochemistry; and INC-7, Isotope Geochemistry. The procedures fall into five categories: I. Separation of Radionuclides from Uranium, Fission-Product Solutions, and Nuclear Debris; II. Separation of Products from Irradiated Targets; III. Preparation of Samples for Mass Spectrometric Analysis; IV. Dissolution Procedures; and V. Geochemical Procedures. With one exception, the first category of procedures is ordered by the positions of the elements in the Periodic Table, with separate parts on the Representative Elements (the A groups); the d-Transition Elements (the B groups and the Transition Triads); and the Lanthanides (Rare Earths) and Actinides (the 4f- and 5f-Transition Elements). The members of Group IIIB-- scandium, yttrium, and lanthanum--are included with the lanthanides, elements they resemble closely in chemistry and with which they occur in nature. The procedures dealing with the isolation of products from irradiated targets are arranged by target element.

  4. Eastern Devonian shales: Organic geochemical studies

    SciTech Connect

    Berger, I.A.; Hatchner, P.G.; Miknis, F.P.; Romankiw, L.A.

    1983-02-01

    The Eastern Devonian shales are represented by a sequence of sediments extending from New York state, south to the northern regions of Georgia and Alabama, and west into Ohio and to the Michigan and Illinois Basins. Correlatives are known in Texas. The shale is regionally known by a number of names: Chattanooga, Dunkirk, Rhinestreet, Huron, Antrim, Ohio, Woodford, etc. These shales, other than those in Texas, have elicited much interest because they have been a source of unassociated natural gas. It is of particular interest, however, that most of these shales have no associated crude oil, in spite of the fact that they have some of the characteristics normally attributed to source beds. This paper addresses some of the organic geochemical aspects of the kerogen in these shales, in relation to their oil generating potential. Past organic geochemical studies on Eastern Devonian shales are reviewed. Recent solid state /sup 13/C NMR studies on the nature of the organic matter in Eastern Devonian shales show that Eastern Devonian shales contain a larger fraction of aromatic carbon in their chemical composition. Thus, despite their high organic matter contents, their potential as a petroleum source rock is low, because the kerogen in these shales is of a ''coaly'' nature and hence more prone to producing natural gas.

  5. Geochemical processes in landfills

    NASA Astrophysics Data System (ADS)

    Förstner, Ulrich; Kersten, Michael; Wienberg, Reinhard

    The present review focusses on the qualitative long-term perspectives of processes and mechanisms controlling the interactions of critical pollutants with organic and inorganic substrates both in "reactor landfills" and in deposits, which already consist of rock-like material ("final storage quality"). The behavior of pollutants in landfills is determined by the chemistry of interstitial solutions, i.e. by pH and redox conditions, and concentration of inorganic and organic ligands; in "reactor landfills" these conditions are widely variable as a result of biochemical reactions, while "final storage quality" implies less variations of chemical interactions. In both alternatives, however, prediction of short- and long-term effects on groundwater quality should be based on the proportion of "active species" of compounds ("mobility concept"). Qualitative assessment of potentially mobile pollutants may involve a controlled significative intensivation of important parameters such as pH-values. Using sequential extraction rearrangements of specific solid "phases" can be evaluated prior to the actual remobilisation of the pollutant into the dissolved phase. From a geochemical point of view the "reactor landfill" is characterized by labile conditions during the initial aerobic and acid anaerobic phases, the former mainly due to uncontrolled interactions with organic solutes. On the other hand, final storage quality, which is defined by the composition of earth crust material, in most cases is not attained by simple incineration of municipal waste, i.e. by reduction of organic fractions only. There is, in particular, the problem of easily soluble minerals, such as chlorides. Nonetheless the type of inorganic residue deposits will increasingly receive prevalence as a method of final storage for municipal wastes in the future.

  6. Analogue models of pull-apart basins

    NASA Astrophysics Data System (ADS)

    McClay, Ken; Dooley, Tim

    1995-08-01

    Sandbox analogue models of pull-apart basins that developed in sedimentary strata above releasing steps in underlying basement faults are characterized by rhombic basins that are flat-bottomed box grabens with a subhorizontal synkinematic basin infill. Steep to nearly vertical, sigmoidal oblique-slip and segmented oblique-extensional faults are the dominant bounding structures of the pull-apart basins. Cross-basin, short-cut faults link the offset principal displacement zones that are characterized by flower structure development. The structural architectures of the physical models compare directly in form and dimensions to natural examples of strike-slip pull-apart basins.

  7. Ranking Geochemical Energy Availability in Hydrothermal Ecosystems

    NASA Astrophysics Data System (ADS)

    Holland, M. E.; Shock, E. L.; Meyer-Dombard, D.; Amend, J. P.

    2004-12-01

    The energy available to hyperthermophilic microorganisms in hot springs can be theoretically estimated using thermodynamic calculations based on geochemical measurements. The relative abundance of different geochemical energy sources (the "ranking" of these reactions) in particular hot springs may provide one explanation for the differences in hot spring microbial communities and also facilitate the culture of ecologically-relevant microorganisms. Geochemical sampling of seven Yellowstone National Park hot springs was repeated five times from 1999 to 2004 with the intent to compare the geochemistry and geochemical energy available to microorganisms. These seven hot springs were located in three separate regions of Yellowstone National Park: three hot springs, including Obsidian Pool, were sampled in the Mud Volcano area; two in the Sylvan Springs area (Gibbon Meadows); and one each in Imperial Meadows and Sentinel Meadows (Lower Geyser Basin). The hot springs were 75 to 93° C (with one 65° C exception) and spanned the bulk of the pH range at Yellowstone (pH 1.8 to 7.6). Geochemical measurements made on hot springs included redox-active species containing C, N, O, H, S, and Fe; these species were measured by field spectrophotometry and ion chromatography of fluid samples and gas chromatographic analysis of gas samples. From these measurements chemical affinities were calculated for 179 inorganic reactions which encompass the suite of autotrophic energy sources potentially available in each pool. Composite affinities for each reaction were compiled for each of the seven primary pools. The composite for each pool was assembled from repeat measurements from the primary pool as well as nearby pools with similar geochemistry. Calculations show that over half of these inorganic reactions could provide enough energy for a microorganism to survive, based on the threshold value of energy required by {it E. coli} (20 kJ per mole of electron pairs). Some microorganisms

  8. Geochemical data for Colorado soils-Results from the 2006 state-scale geochemical survey

    USGS Publications Warehouse

    Smith, David B.; Ellefsen, Karl J.; Kilburn, James E.

    2010-01-01

    In 2006, soil samples were collected at 960 sites (1 site per 280 square kilometers) throughout the state of Colorado. These samples were collected from a depth of 0-15 centimeters and, following a near-total multi-acid digestion, were analyzed for a suite of more than 40 major and trace elements. The resulting data set provides a baseline for the natural variation in soil geochemistry for Colorado and forms the basis for detecting changes in soil composition that might result from natural processes or anthropogenic activities. This report describes the sampling and analytical protocols used and makes available all the soil geochemical data generated in the study.

  9. Des analogues naturels de sites de stockage de déchets nucléaires vieux de 2 milliards d'années : les réacteurs de fission nucléaire naturels du Gabon (Afrique)

    NASA Astrophysics Data System (ADS)

    Gauthier-Lafaye, François

    2002-10-01

    Two billion years ago, the increase of oxygen in atmosphere and the high 235U/ 238U uranium ratio (>3%) made possible the occurrence of natural nuclear reactors on Earth. These reactors are considered to be a good natural analogue for nuclear waste disposal. Their preservation during such a long period of time is mainly due to the geological stability of the site, the occurrence of clays surrounding the reactors and acting as an impermeable shield, and the occurrence of organic matter that maintained the environment in reducing conditions, favourable for the stability of uraninite. Hydrogeochemical studies and modelling have shown the complexity of the geochemical system at Oklo and Bangombé (Gabon) and the lack of precise data about uranium and fission products retention and migration mechanisms in geological environments. To cite this article: F. Gauthier-Lafaye, C. R. Physique 3 (2002) 839-849.

  10. Semisynthetic analogues of the microtubule-stabilizing agent discodermolide: preparation and biological activity.

    PubMed

    Gunasekera, Sarath P; Longley, Ross E; Isbrucker, Richard A

    2002-12-01

    A series of 12 semisynthetic discodermolide analogues, 2-13, have been prepared using natural (+)-discodermolide (1) and evaluated for in vitro cytotoxicity against cultured murine P-388 leukemia and A-549 human adenocarcinoma cells. These semisynthetic analogues showed a significant variation of cytotoxicity and confirmed the importance of the C-7 through C-19 molecular fragment for potency. Specifically, these analogues suggested the importance of the C-11 and C-17 hydroxyl groups and the C-13 double bond for the potency of discodermolide. The preparation, structure elucidation, and biological activity of these new analogues are described.

  11. Condensed matter analogues of cosmology

    NASA Astrophysics Data System (ADS)

    Kibble, Tom; Srivastava, Ajit

    2013-10-01

    liveliest. A number of new experiments are reported here studying the dynamical evolution of domains and defects. Another phenomenon that played a key early role was the formation of vortices in the normal-to-superfluid transition in liquid helium-3. The complicated nature of the order parameter energy surface gives rise to a variety of intriguing effects. This too is still a vigorous field. Superconductivity is a special case because the symmetry that is broken is a gauge symmetry. This is also true in fundamental particle physics theories of relevance to cosmology, and for that reason experiments on superconductors are of particular interest to cosmologists. The situation in this case is more complicated because there are competing mechanisms of defect formation. Experiments in the field have not proved easy, either to perform or to interpret, but the papers in this collection show that good progress has been made of late. In recent years a new type of system has proved immensely fruitful, namely atomic Bose-Einstein or Fermi-gas condensates. Experiments on condensates with tunable parameters have in general provided broad support for the theory, and have also revealed a wide range of interesting and novel features, with intriguing possible analogues in cosmology (e.g. causal horizons and particle creation). The basic idea of the Kibble-Zurek mechanism has been shown to be relevant in this whole range of systems. But numerous complexities have also emerged, concerned for example with the role of inhomogeneity or the existence of composite defects. The field is still developing rapidly. Acknowledgments Finally, we would like to thank all the authors who have contributed to this issue, and the staff of Journal of Physics: Condensed Matter who have made it possible. Condensed matter analogues of cosmology contents Condensed matter analogues of cosmologyTom Kibble and Ajit Srivastava Symmetry breaking in nematic liquid crystals: analogy with cosmology and magnetismR Repnik, A

  12. Acetylated analogues of the microtubule-stabilizing agent discodermolide: preparation and biological activity.

    PubMed

    Gunasekera, S P; Longley, R E; Isbrucker, R A

    2001-02-01

    A series of eight discodermolide acetates have been prepared using natural (+)-discodermolide and evaluated for in vitro cytotoxicity against the cultured murine P-388 leukemia cells. The acetylated analogues showed a significant variation of cytotoxicity and suggested the importance of C-11 and C-17 hydroxyl groups for potency. The preparation and structure elucidation of the new analogues are described.

  13. Analogues of uracil nucleosides with intrinsic fluorescence (NIF-analogues): synthesis and photophysical properties.

    PubMed

    Segal, Meirav; Fischer, Bilha

    2012-02-28

    Uridine cannot be utilized as fluorescent probe due to its extremely low quantum yield. For improving the uracil fluorescence characteristics we extended the natural chromophore at the C5 position by coupling substituted aromatic rings directly or via an alkenyl or alkynyl linker to create fluorophores. Extension of the uracil base was achieved by treating 5-I-uridine with the appropriate boronic acid under the Suzuki coupling conditions. Analogues containing an alkynyl linker were obtained from 5-I-uridine and the suitable boronic acid in a Sonogashira coupling reaction. The uracil fluorescent analogues proposed here were designed to satisfy the following requirements: a minimal chemical modification at a position not involved in base-pairing, resulting in relatively long absorption and emission wavelengths and high quantum yield. 5-((4-Methoxy-phenyl)-trans-vinyl)-2'-deoxy-uridine, 6b, was found to be a promising fluorescent probe. Probe 6b exhibits a quantum yield that is 3000-fold larger than that of the natural chromophore (Φ 0.12), maximum emission (478 nm) which is 170 nm red shifted as compared to uridine, and a Stokes shift of 143 nm. In addition, since probe 6b adopts the anti conformation and S sugar puckering favored by B-DNA, it makes a promising nucleoside analogue to be incorporated in an oligonucleotide probe for detection of genetic material.

  14. Modeling Low-temperature Geochemical Processes

    NASA Astrophysics Data System (ADS)

    Nordstrom, D. K.

    2003-12-01

    Geochemical modeling has become a popular and useful tool for a wide number of applications from research on the fundamental processes of water-rock interactions to regulatory requirements and decisions regarding permits for industrial and hazardous wastes. In low-temperature environments, generally thought of as those in the temperature range of 0-100 °C and close to atmospheric pressure (1 atm=1.01325 bar=101,325 Pa), complex hydrobiogeochemical reactions participate in an array of interconnected processes that affect us, and that, in turn, we affect. Understanding these complex processes often requires tools that are sufficiently sophisticated to portray multicomponent, multiphase chemical reactions yet transparent enough to reveal the main driving forces. Geochemical models are such tools. The major processes that they are required to model include mineral dissolution and precipitation; aqueous inorganic speciation and complexation; solute adsorption and desorption; ion exchange; oxidation-reduction; or redox; transformations; gas uptake or production; organic matter speciation and complexation; evaporation; dilution; water mixing; reaction during fluid flow; reaction involving biotic interactions; and photoreaction. These processes occur in rain, snow, fog, dry atmosphere, soils, bedrock weathering, streams, rivers, lakes, groundwaters, estuaries, brines, and diagenetic environments. Geochemical modeling attempts to understand the redistribution of elements and compounds, through anthropogenic and natural means, for a large range of scale from nanometer to global. "Aqueous geochemistry" and "environmental geochemistry" are often used interchangeably with "low-temperature geochemistry" to emphasize hydrologic or environmental objectives.Recognition of the strategy or philosophy behind the use of geochemical modeling is not often discussed or explicitly described. Plummer (1984, 1992) and Parkhurst and Plummer (1993) compare and contrast two approaches for

  15. Geochemical Origin of Biological Molecules

    NASA Astrophysics Data System (ADS)

    Bassez, Marie-Paule

    2013-04-01

    Conference and abstract in OLEB, 2008, 39 (3-4) 223. BASSEZ M.P. 2009 Prebiotic synthesis under hydothermal conditions, C. R. Chimie, Académie des Sciences, Paris 12 (6-7) : 801-807. BASSEZ M.P. 2012 A model for a geochemical origin of life in preparation BASSEZ M.P., TAKANO Y., OHKOUCHI N. 2009a Organic analysis of peridotite rocks from Ashadze and Logatchev hydrothermal sites, Int. J. Mol. Sci. 10(7): 2986-2998. BASSEZ M.P., TAKANO Y., OHKOUCHI N. 2009b Organic analysis of peridotite rocks from the MAR, AGU fall meeting, P43C-1441, San Francisco, 14-18/12/2009. BASSEZ M.P., TAKANO Y. 2010a Prebiotic organic globules, Nature Precedings: Posted 21 Jul http://hdl:10101/npre.2010.4694.1. BASSEZ M.P., TAKANO Y., OHKOUCHI N. 2010b Organic analysis of peridotite rocks, First chemical steps towards the Origin of Life colloquium, Turin 16-17/09/2010. BASSEZ M.P., TAKANO Y., OHKOUCHI N. 2011a A search for prebiotic molecular signatures inside rocks, Geobiology in Space exploration workshop, P sans n°, Marrakech 07-14/02/2011. BASSEZ M.P., TAKANO Y., OHKOUCHI N. 2011b Detection of molecular biosignatures inside rocks, Origins 2011 ISSOL and Bioastronomy conference, P2-17, Montpellier, 04-08/07/2011. BASSEZ M.P., TAKANO Y., 2011c Organic microstructures, Origins 2011 ISSOL and Bioastronomy conference, P2-34, Montpellier, 04-08/07/2011. BASSEZ M.P., TAKANO Y. KOBAYASHI K. 2011d Prebiotic organic microstructures, Nature Precedings: Posted 14 Nov. http://hdl.handle.net/10101/npre.2011.4694.2 BASSEZ M.P., TAKANO Y., KOBAYASHI K. 2012a Prebiotic organic microstructures, Origin of Life Gordon Research Conference P4, Galveston, 08-13/01/2012. BASSEZ M.P., TAKANO Y., KOBAYASHI K. 2012b Prebiotic organic microstructures, Orig. Life Evol. Biosph. 42 (4) : 307-316.

  16. Perspective of Using the Results of Monitoring and Modeling of the Chernobyl Nuclear Power Plant's Cooling Pond as Analogue for the US DOE Contaminated Sites

    NASA Astrophysics Data System (ADS)

    Faybishenko, B.; Voitsekhovich, O. V.; Bugay, D.; Skalskjj, A.; Shestopalov, V. M.; Zheleznyak, M.; Kashparov, V. A.; Antropov, A. S.; Kireev, S. I.; Bondarkov, M. D.; Ivanov, Y.; Oskolkov, B.; Marra, J.; Jannik, T.; Farfan, E.; Monken-Fernandes, H.; Hinton, T.; Smith, J.; Onishi, Y.; Konoplev, A.

    2010-12-01

    Although there are many contaminated sites that may be suitable candidates for providing analogue information for the development and testing of environmental modeling and risk assessment approaches, of particular scientific and practical interests is the feasibility study of planned decommissioning and remediation of the highly contaminated Chernobyl Cooling Pond (CP), located within the Chernobyl Exclusion Zone (ChEZ). The presence of the CP has caused an artificially high groundwater table within the ChEZ. After the planned cessation of water pumping from the Pripyat River to the CP, substantial areas of sediments, containing 137Cs, 90Sr, and hot particles with U, Pu, and Am. will be exposed to the atmosphere, and the groundwater level is expected to decline by as much as 7 m. The areal extent of the exposed zone, the dissolution rate, mobility and bioavailability of radionuclides will vary over time, depending on the dynamics of seepage losses from the pond and climatic conditions. The objective of the presentation is to discuss hydrological and geochemical processes, a conceptual model, and the results and perspectives of numerical modeling of coupled surface water-groundwater flow and transport, including the parameter estimation and uncertainty evaluation for various decommissioning and remediation options of the CP. In particular, the results of 1D, 2D, and 3D simulations of radionuclide transport in surface water and groundwater will be discussed, along with the evaluation of Kd parameters from the results of field monitoring and modeling of seasonal variations of 137Cs concentrations in pond water and sediments. It will be shown that the results of field monitoring and modeling of the Chernobyl CP can be used as analogue for several US DOE sites to improve scientific and practical understanding of subsurface hydrological and geochemical processes, as well as to obtain a better understanding of processes affecting natural attenuation of radionuclides in

  17. Five new discodermolide analogues from the marine sponge Discodermia species.

    PubMed

    Gunasekera, Sarath P; Paul, Gopal K; Longley, Ross E; Isbrucker, Richard A; Pomponi, Shirley A

    2002-11-01

    Discodermolide (1) and five new discodermolide analogues trivially named 2-epi-discodermolide (2), 2-des-methyldiscodermolide (3), 5-hydroxymethyldiscodermolate (4), 19-des-aminocarbonyldiscodermolide (5), and 9(13)-cyclodiscodermolide (6) have been isolated from marine sponges belonging to the genus Discodermia collected from the Caribbean Sea. The isolation, structure elucidation, and biological activities of 2-6 are described. The natural analogues, which were isolated in trace amounts, exhibited significant variation of cytotoxicity against the cultured murine P-388 leukemia and A-549 human adenocarcinoma cells and suggested the importance of the C(7) through C(17) moiety for potency against cultured tumor cell lines.

  18. Synthesis and Cytotoxicity of Semisynthetic Withalongolide A Analogues

    PubMed Central

    2013-01-01

    The natural product withaferin A exhibits potent antitumor activity and other diverse pharmacological activities. The recently discovered withalongolide A, a C-19 hydroxylated congener of withaferin A, was recently reported to possess cytotoxic activity against head and neck squamous cell carcinomas. Semisynthetic acetylated analogues of withalongolide A were shown to be considerably more cytotoxic than the parent compound. To further explore the structure–activity relationships, 20 new semisynthetic analogues of withalongolide A were synthesized and evaluated for cytotoxic activity against four different cancer cell lines. A number of derivatives were found to be more potent than the parent compound and withaferin A. PMID:24273633

  19. Paired Magmatic-Metallogenic Belts in Myanmar - an Andean Analogue?

    NASA Astrophysics Data System (ADS)

    Gardiner, Nicholas; Robb, Laurence; Searle, Michael; Morley, Christopher

    2015-04-01

    Myanmar (Burma) is richly endowed in precious and base metals, having one of the most diverse collections of natural resources in SE Asia. Its geological history is dominated by the staged closing of Tethys and the suturing of Gondwana-derived continental fragments onto the South China craton during the Mesozoic-Cenozoic. The country is located at a crucial geologic juncture where the main convergent Tethyan collision zone swings south around the Namche Barwa Eastern Himalayan syntaxis. However, despite recent work, the geological and geodynamic history of Myanmar remains enigmatic. Plate margin processes, magmatism, metasomatism and the genesis of mineral deposits are intricately linked, and there has long been recognized a relationship between the distribution of certain mineral deposit types, and the tectonic settings which favour their genesis. A better knowledge of the regional tectonic evolution of a potential exploration jurisdiction is therefore crucial to understanding its minerals prospectivity. This strong association between tectonics and mineralization can equally be applied in reverse. By mapping out the spatial, and temporal, distribution of presumed co-genetic mineral deposits, coupled with an understanding of their collective metallogenetic origin, a better appreciation of the tectonic evolution of a terrane may be elucidated. Identification and categorization of metallotects within a geodynamically-evolving terrane thus provides a complimentary tool to other methodologies (e.g. geochemical, geochronological, structural, geophysical, stratigraphical), for determining the tectonic history and inferred geodynamic setting of that terrane through time. Myanmar is one such study area where this approach can be undertaken. Here are found two near-parallel magmatic belts, which together contain a significant proportion of that country's mineral wealth of tin, tungsten, copper, gold and silver. Although only a few 100 km's apart, these belts exhibit a

  20. Synthesis and Biological Evaluation of Carbocyclic Analogues of Pachastrissamine

    PubMed Central

    Kwon, Yongseok; Song, Jayoung; Bae, Hoon; Kim, Woo-Jung; Lee, Joo-Youn; Han, Geun-Hee; Lee, Sang Kook; Kim, Sanghee

    2015-01-01

    A series of carbocyclic analogues of naturally-occurring marine sphingolipid pachastrissamine were prepared and biologically evaluated. The analogues were efficiently synthesized via a tandem enyne/diene-ene metathesis reaction as a key step. We found that the analogue 4b exhibited comparable cytotoxicity and more potent inhibitory activity against sphingosine kinases, compared to pachastrissamine. Molecular modeling studies were conducted to provide more detailed insight into the binding mode of 4b in sphingosine kinase. In our docking model, pachastrissamine and 4b were able to effectively bind to the binding pocket of sphingosine kinase 1 as co-crystalized sphingosine. However, 4b showed a hydrophobic interaction with Phe192, which suggests that it contributes to its increased inhibitory activity against sphingosine kinase 1. PMID:25654428

  1. Migrastatin analogues target fascin to block tumour metastasis

    SciTech Connect

    Chen, L.; Jakoncic, J.; Yang, S.; Zhang, J.; Huang, X.Y.

    2010-04-15

    Tumour metastasis is the primary cause of death of cancer patients. Development of new therapeutics preventing tumour metastasis is urgently needed. Migrastatin is a natural product secreted by Streptomyces, and synthesized migrastatin analogues such as macroketone are potent inhibitors of metastatic tumour cell migration, invasion and metastasis. Here we show that these migrastatin analogues target the actin-bundling protein fascin to inhibit its activity. X-ray crystal structural studies reveal that migrastatin analogues bind to one of the actin-binding sites on fascin. Our data demonstrate that actin cytoskeletal proteins such as fascin can be explored as new molecular targets for cancer treatment, in a similar manner to the microtubule protein tubulin.

  2. New rubrolide analogues as inhibitors of photosynthesis light reactions.

    PubMed

    Varejão, Jodieh O S; Barbosa, Luiz C A; Ramos, Gabriela Álvarez; Varejão, Eduardo V V; King-Díaz, Beatriz; Lotina-Hennsen, Blas

    2015-04-01

    Natural products called rubrolides have been investigated as a model for the development of new herbicides that act on the photosynthesis apparatus. This study comprises a comprehensive analysis of the photosynthesis inhibitory ability of 27 new structurally diverse rubrolide analogues. In general, the results revealed that the compounds exhibited efficient inhibition of the photosynthetic process, but in some cases low water solubility may be a limiting factor. To elucidate their mode of action, the effects of the compounds on PSII and PSI, as well as their partial reaction on chloroplasts and the chlorophyll a fluorescence transients were measured. Our results showed that some of the most active rubrolide analogues act as a Hill reaction inhibitors at the QB level by interacting with the D1 protein at the reducing side of PSII. All of the active analogues follow Tice's rule of 5, which indicates that these compounds present physicochemical properties suitable for herbicides.

  3. Theoretical study on absorption and emission spectra of adenine analogues.

    PubMed

    Liu, Hongxia; Song, Qixia; Yang, Yan; Li, Yan; Wang, Haijun

    2014-04-01

    Fluorescent nucleoside analogues have attracted much attention in studying the structure and dynamics of nucleic acids in recent years. In the present work, we use theoretical calculations to investigate the structural and optical properties of four adenine analogues (termed as A1, A2, A3, and A4), and also consider the effects of aqueous solution and base pairing. The results show that the fluorescent adenine analogues can pair with thymine to form stable H-bonded WC base pairs. The excited geometries of both adenine analogues and WC base pairs are similar to the ground geometries. The absorption and emission maxima of adenine analogues are greatly red shifted compared with nature adenine, the oscillator strengths of A1 and A2 are stronger than A3 and A4 in both absorption and emission spectra. The calculated low-energy peaks in the absorption spectra are in good agreement with the experimental data. In general, the aqueous solution and base pairing can slightly red-shift both the absorption and emission maxima, and can increase the oscillator strengths of absorption spectra, but significantly decrease the oscillator strengths of A3 in emission spectra.

  4. 3-fluoro- and 3,3-difluoro-3,4-dideoxy-KRN7000 analogues as new potent immunostimulator agents: total synthesis and biological evaluation in human invariant natural killer T cells and mice.

    PubMed

    Hunault, Julie; Diswall, Mette; Frison, Jean-Cédric; Blot, Virginie; Rocher, Jézabel; Marionneau-Lambot, Séverine; Oullier, Thibauld; Douillard, Jean-Yves; Guillarme, Stéphane; Saluzzo, Christine; Dujardin, Gilles; Jacquemin, Denis; Graton, Jérôme; Le Questel, Jean-Yves; Evain, Michel; Lebreton, Jacques; Dubreuil, Didier; Le Pendu, Jacques; Pipelier, Muriel

    2012-02-01

    We propose here the synthesis and biological evaluation of 3,4-dideoxy-GalCer derivatives. The absence of the 3- and 4-hydroxyls on the sphingoid base is combined with the introduction of mono or difluoro substituent at C3 (analogues 8 and 9, respectively) to evaluate their effect on the stability of the ternary CD1d/GalCer/TCR complex which strongly modulate the immune responses. Biological evaluations were performed in vitro on human cells and in vivo in mice and results discussed with support of modeling studies. The fluoro 3,4-dideoxy-GalCer analogues appears as partial agonists compared to KRN7000 for iNKT cell activation, inducing T(H)1 or T(H)2 biases that strongly depend of the mode of antigen presentation, including human vs mouse differences. We evidenced that if a sole fluorine atom is not able to balance the loss of the 3-OH, the presence of a difluorine group at C3 of the sphingosine can significantly restore human iNKT activation.

  5. IRETHERM: Developing a Strategic and Holistic Understanding of Ireland's Geothermal Energy Potential through Integrated Modelling of New and Existing Geophysical, Geochemical and Geological Data

    NASA Astrophysics Data System (ADS)

    Jones, Alan G.; Daly, Stephen; Vozar, Jan; Rath, Volker; Campanya, Joan; Blake, Sarah; Delhaye, Robert; Fritschle, Tobias; Willmot Noller, Nicola; Long, Mike; Waters, Tim

    2015-04-01

    The Science Foundation Ireland funded academia-government-industry collaborative IRETHERM project (www.iretherm.ie), initiated in 2011, is developing a strategic understanding of Ireland's (all-island) deep geothermal energy potential through integrated modelling of new and existing geophysical, geochemical and geological data. Potential applications include both low enthalpy district space heating of large urban centres and electricity generation from intermediate-temperature waters. IRETHERM comprises three broad geothermal target types; 1) Assessment of the geothermal energy potential of Ireland's radiogenic granites (EGS), (2) Assessment of the geothermal energy potential of Ireland's deep sedimentary basins (HSA), and, (3) Assessment of the geothermal energy potential of warm springs. The geophysical subsurface imaging techniques of choice are controlled-source (CSEM) and natural-source (magnetotellurics, MT) electromagnetic methods. Electrical conductivity, being a transport property, is a proxy for permeability, and appropriate porosity-permeability relations are being developed. To date, MT measurements have been made at 466 sites over sedimentary basins (190 sites), granites (156 sites) and warm springs (120 sites), with CSEM across one warm spring. An ongoing continuous geochemical (temperature and electrical conductivity every 15 mins) and time-lapse seasonal hydrochemical sampling programmes are in progress at six warm spring sites. A database on heat production in Irish rocks has been compiled, of more than 3,300 geochemical sample measurements, with 3,000 retrieved from various archives and over 300 new analyses. Geochemistry, geochronology and isotopic analyses have been conducted on subsurface granites and exposed analogues astride the Iapetus Suture Zone in order to understand the underlying reasons for their radiogenic heat production. Finally, thermal conductivity measurements have been made on borehole samples from representative lithologies

  6. Simultaneous preparation of four truncated analogues of discodermolide by fluorous mixture synthesis.

    PubMed

    Curran, Dennis P; Furukawa, Takashi

    2002-06-27

    [structure: see text] Four truncated analogues of the natural product discodermolide were synthesized in a single synthetic sequence. Precursors bearing four different groups at C22, each with a unique fluorous p-methoxybenzyl substituent on the C17 hydroxy group, were mixed and taken through an nine-step sequence. Demixing by fluorous chromatography followed by deprotection and purification provided the individual analogues in 3-7% overall yields and with a savings of 24 synthetic steps. Fluorous mixture synthesis is recommended as a new technique to make multiple natural product analogues in a single multistep synthesis.

  7. Geochemical cycles of atmospheric gases

    NASA Technical Reports Server (NTRS)

    Walker, J. C. G.; Drever, J. I.

    1988-01-01

    The processes that control the atmosphere and atmospheric changes are reviewed. The geochemical cycles of water vapor, nitrogen, carbon dioxide, oxygen, and minor atmospheric constituents are examined. Changes in atmospheric chemistry with time are discussed using evidence from the rock record and analysis of the present atmosphere. The role of biological evolution in the history of the atmosphere and projected changes in the future atmosphere are considered.

  8. Synthetic isoprenoid analogues for the study of prenylated proteins: Fluorescent imaging and proteomic applications.

    PubMed

    Wang, Yen-Chih; Distefano, Mark D

    2016-02-01

    Protein prenylation is a posttranslational modification catalyzed by prenyltransferases involving the attachment of farnesyl or geranylgeranyl groups to residues near the C-termini of proteins. This irreversible covalent modification is important for membrane localization and proper signal transduction. Here, the use of isoprenoid analogues for studying prenylated proteins is reviewed. First, experiments with analogues containing small fluorophores that are alternative substrates for prenyltransferases are described. Those analogues have been useful for quantifying binding affinity and for the production of fluorescently labeled proteins. Next, the use of analogues that incorporate biotin, bioorthogonal groups or antigenic moieties is described. Such probes have been particularly useful for identifying proteins that are naturally prenylated within mammalian cells. Overall, the use of isoprenoid analogues has contributed significantly to the understanding of protein prenlation.

  9. Phosphonate analogue substrates for enolase.

    PubMed

    Anderson, V E; Cleland, W W

    1990-11-20

    Phosphonate analogues in which the bridge between C-2 and phosphorus is a CH2 group are slow substrates for yeast enolase. The pH variation of the kinetic parameters for the methylene analogue of 2-phosphoglycerate suggests that the substrate binds as a dianion and that Mg2+ can bind subsequently only if a metal ligand and the catalytic base are unprotonated. Primary deuterium isotope effects of 4-8 on V/KMg, but ones of only 1.15-1.32 on V for dehydration, show that proton removal to give the carbanion intermediate largely limits V/KMg and that a slow step follows which largely limits V (presumably carbanion breakdown). Since there is a D2O solvent isotope effect on V for the reverse reaction of 5, but not an appreciable one on the forward reaction, it appears that the slow rates with phosphonate analogues result from the fact that the carbanion intermediate is more stable than that formed from the normal substrates, and its reaction in both directions limits V. Increased stability as a result of replacement of oxygen by carbon at C-2 of the carbanion is the expected chemical behavior. PMID:2271661

  10. Substrate analogues for isoprenoid enzymes

    SciTech Connect

    Stremler, K.E.

    1987-01-01

    Diphosphonate analogues of geranyl diphosphate, resistant to degradation by phosphatases, were found to be alternate substrates for the reaction with farnesyl diphosphate synthetase isolated from avian liver. The difluoromethane analogue was shown to be the better alternate substrate, in agreement with solvolysis results which indicate that the electronegativity of the difluoromethylene unit more closely approximates that of the normal bridging oxygen. The usefulness of the C/sub 10/ difluoro analogue, for detecting low levels of isoprenoid enzymes in the presence of high levels of phosphatase activity, was demonstrated with a cell-free preparation from lemon peel. A series of C/sub 5/ through C/sub 15/ homoallylic and allylic diphosphonates, as well as two 5'-nucleotide diphosphonates, was prepared in high overall yield using the activation-displacement sequence. Radiolabeled samples of several of the allylic diphosphonates were prepared with tritium located at C1. A series of geraniols, stereospecifically deuterated at C1, was prepared. The enantiomeric purities and absolute configurations were determined by derivatization as the mandelate esters for analysis by /sup 1/H NMR. The stereochemistry of the activation-displacement sequence was examined using C1-deuterated substrates.

  11. Policy issues in space analogues

    NASA Astrophysics Data System (ADS)

    Auger, Robin N.; Facktor, Debra D.

    Space mission planning is increasingly focusing on destinations beyond Earth orbit. Advancements in technology will inevitably be required to enable long-duration human spaceflight missions, and breakthroughs in the policy arena will also be needed to achieve success in such missions. By exploring how policy issues have been addressed in analogous extreme environments, policymakers can develop a framework for addressing these issues as they apply to long-term human spaceflight. Policy issues that need to be addressed include: crew selection, training, organization, and activities, medical testing, illness, injury, and death; communication; legal accountability and liability; mission safety and risk management; and environmental contamination. This paper outlines the approach of a study underway by The George Washington University and ANSER to examine how these policy issues have been addressed in several analogues and how the experiences of these analogues can help formulate policies for long-duration human spaceflight missions. Analogues being studied include Antarctic bases, submarine voyages, undersea stations, Biosphere 2, and the U.S. Skylab and Russian Mir space stations.

  12. Alligator rivers analogue project an OECD/NEA international project

    SciTech Connect

    Duerden, P.; Airey, P.; Pescatore, C.

    1994-12-31

    The Koongarra uranium deposit in the Alligator Rivers Region of the Northern Territory of Australia was studied as a natural analogue of the far field behaviour of high level waste repositories following groundwater ingress. A number of mathematical modelling approaches were developed for processes as diverse as groundwater transport, host rock weathering, radionuclide sorption, evolution of the uranium dispersion fan and the distribution of uranium series nuclides between mineral assemblages in weathered host rock. Some of these models are relevant to performance assessment at the level of individual processes and subsystem performance. Through the project, new insights into the application of the natural analogue approach to the assessment of potential waste repository sites were obtained.

  13. Geochemical Arrays at Woolsey Mound Seafloor Observatory

    NASA Astrophysics Data System (ADS)

    Sleeper, K.; Wilson, R. M.; Chanton, J.; Lapham, L.; Farr, N.; Camilli, R.; Martens, C. S.; Pontbriand, C.

    2011-12-01

    incorporated into the Benthic Boundary Layer Array for high-speed, wireless data transmission. Combining this system with a cabled observatory will allow real-time monitoring of gas hydrates in the natural environment. The arrays have each been deployed at the Woolsey Mound Seafloor Observatory for extended durations. Woolsey Mound is at a depth of approximately 900m on the continental slope of the northern Gulf of Mexico in Mississippi Canyon Federal Lease Block 118. The Observatory is a multi-component facility that will have geophysical and microbial components in addition to the geochemical arrays described here. The goal of the Observatory is to develop a facility to evaluate the formation and stability of gas hydrates in a natural system. Specific areas of interest include geohazards, alternative energy resources, climate change and unique, deep- marine habitats. The poster presents the major geochemical arrays at Woolsey Mound Seafloor Observatory, including their design, sensor specifications, deployment and installation platforms, and scientific relevance.

  14. The role of the "Casimir force analogue" at the microscopic processes of crystallization and melting

    NASA Astrophysics Data System (ADS)

    Chuvildeev, V. N.; Semenycheva, A. V.

    2016-10-01

    Melting (crystallization), a phase transition from a crystalline solid to a liquid state, is a common phenomenon in nature. We suggest a new factor, "the Casimir force analogue", to describe mechanisms of melting and crystallization. The Casimir force analogue is a force occurring between the surfaces of solid and liquid phases of metals caused by different energy density of phonons of these phases. It explains abrupt changes in geometry and thermodynamic parameters at a melting point. "The Casimir force analogue" helps to estimate latent melting heat and to gain an insight into a solid-liquid transition problem.

  15. Synthesis and bioactivity of analogues of the marine antibiotic tropodithietic acid

    PubMed Central

    Rabe, Patrick; Klapschinski, Tim A; Brock, Nelson L; Citron, Christian A; D’Alvise, Paul; Gram, Lone

    2014-01-01

    Summary Tropodithietic acid (TDA) is a structurally unique sulfur-containing antibiotic from the Roseobacter clade bacterium Phaeobacter inhibens DSM 17395 and a few other related species. We have synthesised several structural analogues of TDA and used them in bioactivity tests against Staphylococcus aureus and Vibrio anguillarum for a structure–activity relationship (SAR) study, revealing that the sulfur-free analogue of TDA, tropone-2-carboxylic acid, has an antibiotic activity that is even stronger than the bioactivity of the natural product. The synthesis of this compound and of several analogues is presented and the bioactivity of the synthetic compounds is discussed. PMID:25161739

  16. FUNCTION GENERATOR FOR ANALOGUE COMPUTERS

    DOEpatents

    Skramstad, H.K.; Wright, J.H.; Taback, L.

    1961-12-12

    An improved analogue computer is designed which can be used to determine the final ground position of radioactive fallout particles in an atomic cloud. The computer determines the fallout pattern on the basis of known wind velocity and direction at various altitudes, and intensity of radioactivity in the mushroom cloud as a function of particle size and initial height in the cloud. The output is then displayed on a cathode-ray tube so that the average or total luminance of the tube screen at any point represents the intensity of radioactive fallout at the geographical location represented by that point. (AEC)

  17. Mineralogical and geochemical consequences of the long-term presence of CO2 in natural reservoirs: An example from the Springerville-St. Johns Field, Arizona, and New Mexico, U.S.A

    USGS Publications Warehouse

    Moore, J.; Adams, M.; Allis, R.; Lutz, S.; Rauzi, S.

    2005-01-01

    The Springerville-St. Johns CO2 field in eastern Arizona and western New Mexico is one of more than a dozen gas fields developed within the Colorado Plateau and Southern Rocky Mountain region. Extensive travertine (CaCO3) deposits record a long history of CO2 migration and leakage to the atmosphere. The oldest travertine deposits may have formed during the initial filling of the CO2 reservoir when groundwaters exsolved CO2 upon reaching the surface. The youngest travertine deposits are associated with springs on the floor of the Little Colorado River valley, but travertine deposition appears to be insignificant today. Older deposits occur up to 325 m above the valley floor. Geologic relationships suggest travertine deposition began in the late Pleistocene after volcanic activity ended at ???0.3 Ma. Most of the CaCO3 could have been derived from dissolution of the underlying limestones and dolomites. Interactions between the reservoir fluids and rocks were observed in core samples from one of the intervals that produced dry gas. These reactions resulted in the dissolution of carbonate cements and detrital feldspars and the formation of dawsonite and kaolinite. Geochemical simulations suggest that the dawsonite could have been deposited when the CO2 fugacity reached 20 bars and that the kaolinite formed as the CO2 fugacity decreased. Corrosion of drill pipe by acidic waters and a pronounced HCO3 anomaly above the CO2 reservoir provide evidence of a continuing flux of CO2 from depth. CO2 storage occurs primarily as dissolved carbonate species and as gas accumulations. Only a small percentage of the CO2 was sequestered in secondary minerals. ?? 2005 Elsevier B.V. All rights reserved.

  18. Validation of the WATEQ4 geochemical model for uranium

    SciTech Connect

    Krupka, K.M.; Jenne, E.A.; Deutsch, W.J.

    1983-09-01

    As part of the Geochemical Modeling and Nuclide/Rock/Groundwater Interactions Studies Program, a study was conducted to partially validate the WATEQ4 aqueous speciation-solubility geochemical model for uranium. The solubility controls determined with the WATEQ4 geochemical model were in excellent agreement with those laboratory studies in which the solids schoepite (UO/sub 2/(OH)/sub 2/ . H/sub 2/O), UO/sub 2/(OH)/sub 2/, and rutherfordine ((UO/sub 2/CO/sub 3/) were identified as actual solubility controls for uranium. The results of modeling solution analyses from laboratory studies of uranyl phosphate solids, however, identified possible errors in the characterization of solids in the original solubility experiments. As part of this study, significant deficiencies in the WATEQ4 thermodynamic data base for uranium solutes and solids were corrected. Revisions included recalculation of selected uranium reactions. Additionally, thermodynamic data for the hydroxyl complexes of U(VI), including anionic (VI) species, were evaluated (to the extent permitted by the available data). Vanadium reactions were also added to the thermodynamic data base because uranium-vanadium solids can exist in natural ground-water systems. This study is only a partial validation of the WATEQ4 geochemical model because the available laboratory solubility studies do not cover the range of solid phases, alkaline pH values, and concentrations of inorganic complexing ligands needed to evaluate the potential solubility of uranium in ground waters associated with various proposed nuclear waste repositories. Further validation of this or other geochemical models for uranium will require careful determinations of uraninite solubility over the pH range of 7 to 10 under highly reducing conditions and of uranyl hydroxide and phosphate solubilities over the pH range of 7 to 10 under oxygenated conditions.

  19. The Canadian Analogue Research Network (CARN): Opportunities for Terrestrial Analogue Studies in Canada and Abroad

    NASA Astrophysics Data System (ADS)

    Hipkin, V.; Osinski, G. R.; Berinstain, A.; Léveillé, R.

    2007-03-01

    We will present an overview of the Canadian Analogue Research Network (CARN), including a description of the various analogue sites in CARN, potential new sites, and a discussion regarding how CARN is applicable to the global exploration strategy.

  20. Composition of natural gas and crude oil produced from 14 wells in the Lower Silurian "Clinton" Sandstone and Medina Group Sandstones, northeastern Ohio and northwestern Pennsylvania: Chapter G.6 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    USGS Publications Warehouse

    Burruss, Robert A.; Ryder, Robert T.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    The geochemical processes that control the distribution of hydrocarbons in the regional accumulation of natural gas and crude oil in reservoirs of Early Silurian age in the central Appalachian basin are not well understood. Gas and oil samples from 14 wells along a down-dip transect through the accumulation in northeastern Ohio and northwestern Pennsylvania were analyzed for molecular and stable isotopic compositions to look for evidence of hydrocarbon source, thermal maturation, migration, and alteration parameters. The correlation of carbon and hydrogen stable isotopic composition of methane with thermal maturation indicates that the deepest gases are more thermally mature than independent estimates of thermal maturity of the reservoir horizon based on the conodont alteration index. This correlation indicates that the natural gas charge in the deepest parts of the regional accumulation sampled in this study originated in deeper parts of the Appalachian basin and migrated into place. Other processes, including mixing and late-stage alteration of hydrocarbons, may also impact the observed compositions of natural gases and crude oils.

  1. Isotopic fractionation of rare earth elements in geochemical samples

    NASA Astrophysics Data System (ADS)

    Ishibashi, T.; Ohno, T.

    2015-12-01

    The isotopic composition of Rare Earth Elements(REEs) can be fractionated through various physical and chemical reactions in nature [1]. The isotopic variations of REEs occurring naturally has a potentially significant influence in geochemical research fields. The REEs has key features that their chemical similarities and gradual changes of ionic radius, which may help us to understand the mechanisms of isotopic variations of REEs in nature. Among the REEs, geochemical and physicochemical features of Ce, which could be presence as the tetravalent state, be anomalous, and oxidation state of Ce can change by reflecting the redox conditions of the environment. Therefore, the study of the difference in the degree of isotopic fractionation between Ce and other REEs may provide information on the redox conditions. In this study, we developed a new separation method to determine the mass-dependent isotopic fractionations of REEs in geochemical samples, and examined the optimum concentration of hydrochloric acid for the separation. The samples were decomposed by a mixture of acids, then REEs were separated as a group from major elements using cation exchange resin columns and RE Spec resin. The separations within the REEs group were carried out using Ln2Spec resin. For the recovery of La, Ce, Pr, and Nd, 0.1 M HCl was used, and for isolation of Sm, Eu, and Gd, 0.25 M HCl was used. Then, 0.6 M HCl was used for separation of Tb, and Dy, 1 M HCl was used for separation of Ho, Y, and Er, finally, Tm, Yb, and Lu were collected using 2 M HCl. The yields of all REEs were enough to examine isotopic fractionation in geochemical samples. [1] Ohno and Hirata,Analytical Sciences, 29, 271, 2013

  2. Landscape and bio- geochemical strategy for monitoring transformation and reclamation of the soil mining sites

    NASA Astrophysics Data System (ADS)

    Korobova, Elena

    2010-05-01

    Sites of active or abandoned mining represent areas of considerable technogenic impact and need scientifically ground organization of their monitoring and reclamation. The strategy of monitoring and reclamation depends on the scale and character of the physical, chemical and biological consequences of the disturbances. The geochemical studies for monitoring and rehabilitation of the career-dump complexes should methodically account of formation of the particular new landforms and the changes in circulation of the remobilized elements of the soil cover. However, the general strategy should account of both the initial and transformed landscape geochemical structure of the area with due regard to the natural and new content of chemical elements in the environmental components. For example the tailings and waste rocks present new geochemical fields with specifically different concentration of chemical elements that cause formation of new geochemical barriers and landscapes. The way of colonization of the newly formed landscapes depends upon the new geochemical features of the technogenic environment and the adaptive ability of local and intrusive flora. The newly formed biogeochemical anomalies need organization of permanent monitoring not only within the anomaly itself but also of its impact zones. Spatial landscape geochemical monitoring combined with bio-geochemical criteria of threshold concentrations seems to be a helpful tool for decision making on reclamation and operation of the soil mining sites to provide a long-term ecologically sustainable development of the impact zone as a whole.

  3. Insulin, insulin analogues and diabetic retinopathy.

    PubMed

    Chantelau, Ernst; Kimmerle, Renate; Meyer-Schwickerath, Rolf

    2008-02-01

    Insulin is absolutely vital for living beings. It is not only involved in metabolism, but also in the regulation of growth factors, e.g. IGF-1. In this review we address the role insulin has in the natural evolution of diabetic retinopathy. On the one hand, chronic deficiency of insulin and IGF-1 at the retina is thought to cause capillary degeneration, with subsequent ischaemia. On the other hand, acute abundance of (exogenously administered) insulin and IGF-1 enhances ischaemia-induced VEGF expression. A critical ratio of tissue VEGF-susceptibility: VEGF-availability triggers vascular proliferation (i.e. of micro-aneurysms and/or abnormal vessels). The patent-protected insulin analogues Lispro, Glulisine, Aspart, Glargine and Detemir are artificial insulin derivatives with altered biological responses compared to natural insulin (e.g. divergent insulin and /or IGF-1 receptor-binding characteristics, signalling patterns, and mitogenicity). Their safety profiles concerning diabetic retinopathy remain to be established by randomised controlled trials. Anecdotal reports and circumstantial evidence suggest that Lispro and Glargine might worsen diabetic retinopathy.

  4. Proceedings of the workshop on geochemical modeling

    SciTech Connect

    Not Available

    1986-01-01

    The following collection of papers was presented at a workshop on geochemical modeling that was sponsored by the Office of Civilian Radioactive Waste Management Program at the Lawrence Livermore National Laboratory (LLNL). The LLNL Waste Management Program sponsored this conference based on their belief that geochemical modeling is particularly important to the radioactive waste disposal project because of the need to predict the consequences of long-term water-rock interactions at the proposed repository site. The papers included in this volume represent a subset of the papers presented at the Fallen Leaf Lake Conference and cover a broad spectrum of detail and breadth in a subject that reflects the diverse research interests of the conference participants. These papers provide an insightful look into the current status of geochemical modeling and illustrate how various geochemical modeling codes have been applied to problems of geochemical interest. The emphasis of these papers includes traditional geochemical modeling studies of individual geochemical systems, the mathematical and theoretical development and refinement of new modeling capabilities, and enhancements of data bases on which the computations are based. The papers in this proceedings volume have been organized into the following four areas: Geochemical Model Development, Hydrothermal and Geothermal Systems, Sedimentary and Low Temperature Environments, and Data Base Development. The participants of this symposium and a complete list of the talks presented are listed in the appendices.

  5. On the bonding nature of ozone (O3) and its sulfur-substituted analogues SO2, OS2, and S3: correlation between their biradical character and molecular properties.

    PubMed

    Miliordos, Evangelos; Xantheas, Sotiris S

    2014-02-19

    We investigate the bonding mechanism in ozone (O3) and its sulfur-substituted analogues, SO2, OS2, and S3. By analyzing their ground-state multireference configuration interaction wave functions, we demonstrate that the bonding in these systems can be represented as a mixture of a closed-shell structure with one and a half bonds between the central and terminal atoms and an open-shell structure with a single bond and two lone electrons on each terminal atom (biradical). The biradical character (β) further emerges as a simple measure of the relative contribution of those two classical Lewis structures emanating from the interpretation of the respective wave functions. Our analysis yields a biradical character of 3.5% for OSO, 4.4% for SSO, 11% for S3, 18% for O3, 26% for SOO, and 35% for SOS. The size/electronegativity of the end atoms relative to the central one is the prevalent factor for determining the magnitude of β: smaller and more electronegative central atoms better accommodate a pair of electrons facilitating the localization of the remaining two lone π-electrons on each of the end atoms, therefore increasing the weight of the second picture in the mixed bonding scenario (larger β). The proposed mixture of these two bonding scenarios allows for the definition of the bond order of the covalent bonds being (3-β)/2, and this accounts for the different O-O, S-S, or S-O bond lengths in the triatomic series. The biradical character was furthermore found to be a useful concept for explaining several structural and energetic trends in the series: larger values of β mark a smaller singlet-triplet splitting, closer bond lengths in the ground (1)A' and the first excited (3)A' states, and larger bond dissociation and atomization energies in the ground state. The latter explains the relative energy difference between the OSS/SOS and OOS/OSO isomers due to their different β values.

  6. On the bonding nature of ozone (O3) and its sulfur-substituted analogues SO2, OS2, and S3: correlation between their biradical character and molecular properties.

    PubMed

    Miliordos, Evangelos; Xantheas, Sotiris S

    2014-02-19

    We investigate the bonding mechanism in ozone (O3) and its sulfur-substituted analogues, SO2, OS2, and S3. By analyzing their ground-state multireference configuration interaction wave functions, we demonstrate that the bonding in these systems can be represented as a mixture of a closed-shell structure with one and a half bonds between the central and terminal atoms and an open-shell structure with a single bond and two lone electrons on each terminal atom (biradical). The biradical character (β) further emerges as a simple measure of the relative contribution of those two classical Lewis structures emanating from the interpretation of the respective wave functions. Our analysis yields a biradical character of 3.5% for OSO, 4.4% for SSO, 11% for S3, 18% for O3, 26% for SOO, and 35% for SOS. The size/electronegativity of the end atoms relative to the central one is the prevalent factor for determining the magnitude of β: smaller and more electronegative central atoms better accommodate a pair of electrons facilitating the localization of the remaining two lone π-electrons on each of the end atoms, therefore increasing the weight of the second picture in the mixed bonding scenario (larger β). The proposed mixture of these two bonding scenarios allows for the definition of the bond order of the covalent bonds being (3-β)/2, and this accounts for the different O-O, S-S, or S-O bond lengths in the triatomic series. The biradical character was furthermore found to be a useful concept for explaining several structural and energetic trends in the series: larger values of β mark a smaller singlet-triplet splitting, closer bond lengths in the ground (1)A' and the first excited (3)A' states, and larger bond dissociation and atomization energies in the ground state. The latter explains the relative energy difference between the OSS/SOS and OOS/OSO isomers due to their different β values. PMID:24499187

  7. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-11-08

    Overview of an ongoing, 2 year research project partially funded by APRA-E to create a novel, synthetic analogue of carbonic anhydrase and incorporate it into a membrane for removal of CO2 from flue gas in coal power plants. Mechanism background, preliminary feasibility study results, molecular modeling of analogue-CO2 interaction, and program timeline are provided.

  8. Noble gas encapsulation: clathrate hydrates and their HF doped analogues.

    PubMed

    Mondal, Sukanta; Chattaraj, Pratim Kumar

    2014-09-01

    The significance of clathrate hydrates lies in their ability to encapsulate a vast range of inert gases. Although the natural abundance of a few noble gases (Kr and Xe) is poor their hydrates are generally abundant. It has already been reported that HF doping enhances the stability of hydrogen hydrates and methane hydrates, which prompted us to perform a model study on helium, neon and argon hydrates with their HF doped analogues. For this purpose 5(12), 5(12)6(8) and their HF doped analogues are taken as the model clathrate hydrates, which are among the building blocks of sI, sII and sH types of clathrate hydrate crystals. We use the dispersion corrected and gradient corrected hybrid density functional theory for the calculation of thermodynamic parameters as well as conceptual density functional theory based reactivity descriptors. The method of the ab initio molecular dynamics (AIMD) simulation is used through atom centered density matrix propagation (ADMP) techniques to envisage the structural behaviour of different noble gas hydrates on a 500 fs timescale. Electron density analysis is carried out to understand the nature of Ng-OH2, Ng-FH and Ng-Ng interactions. The current results noticeably demonstrate that the noble gas (He, Ne, and Ar) encapsulation ability of 5(12), 5(12)6(8) and their HF doped analogues is thermodynamically favourable. PMID:25047071

  9. Geochemical challenge to earthquake prediction.

    PubMed Central

    Wakita, H

    1996-01-01

    The current status of geochemical and groundwater observations for earthquake prediction in Japan is described. The development of the observations is discussed in relation to the progress of the earthquake prediction program in Japan. Three major findings obtained from our recent studies are outlined. (i) Long-term radon observation data over 18 years at the SKE (Suikoen) well indicate that the anomalous radon change before the 1978 Izu-Oshima-kinkai earthquake can with high probability be attributed to precursory changes. (ii) It is proposed that certain sensitive wells exist which have the potential to detect precursory changes. (iii) The appearance and nonappearance of coseismic radon drops at the KSM (Kashima) well reflect changes in the regional stress state of an observation area. In addition, some preliminary results of chemical changes of groundwater prior to the 1995 Kobe (Hyogo-ken nanbu) earthquake are presented. PMID:11607665

  10. Geochemical data synthesis and analysis

    NASA Technical Reports Server (NTRS)

    Philpotts, J. A.

    1979-01-01

    Data obtained at the Goddard Flight Center were collected for the purpose of completing analyses started at Goddard in order to maximize the scientific yield of the geochemistry program which was terminated in 1977. The major analytical task undertaken was to complete Gd analyses on a large number of samples already analyzed by mass spectrometry for other rare earth element abundances at Goddard. Gd values are important for pinning down the central part of the geochemically significant rare earth abundance pattern and are especially useful in the high precision definition of the utilitarian Eu anomaly. Isotope-dilution Gd abundances were obtained for 39 samples. The data are for 27 partition-coefficient samples, six Apollo 15 and 16 breccia samples, four terrestrial impactities, and associated rock standards.

  11. Continuous analogues of matrix factorizations

    PubMed Central

    Townsend, Alex; Trefethen, Lloyd N.

    2015-01-01

    Analogues of singular value decomposition (SVD), QR, LU and Cholesky factorizations are presented for problems in which the usual discrete matrix is replaced by a ‘quasimatrix’, continuous in one dimension, or a ‘cmatrix’, continuous in both dimensions. Two challenges arise: the generalization of the notions of triangular structure and row and column pivoting to continuous variables (required in all cases except the SVD, and far from obvious), and the convergence of the infinite series that define the cmatrix factorizations. Our generalizations of triangularity and pivoting are based on a new notion of a ‘triangular quasimatrix’. Concerning convergence of the series, we prove theorems asserting convergence provided the functions involved are sufficiently smooth. PMID:25568618

  12. Fully analogue photonic reservoir computer.

    PubMed

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-03-03

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers.

  13. Fully analogue photonic reservoir computer

    PubMed Central

    Duport, François; Smerieri, Anteo; Akrout, Akram; Haelterman, Marc; Massar, Serge

    2016-01-01

    Introduced a decade ago, reservoir computing is an efficient approach for signal processing. State of the art capabilities have already been demonstrated with both computer simulations and physical implementations. If photonic reservoir computing appears to be promising a solution for ultrafast nontrivial computing, all the implementations presented up to now require digital pre or post processing, which prevents them from exploiting their full potential, in particular in terms of processing speed. We address here the possibility to get rid simultaneously of both digital pre and post processing. The standalone fully analogue reservoir computer resulting from our endeavour is compared to previous experiments and only exhibits rather limited degradation of performances. Our experiment constitutes a proof of concept for standalone physical reservoir computers. PMID:26935166

  14. Analogue Transformations in Physics and their Application to Acoustics

    PubMed Central

    García-Meca, C.; Carloni, S.; Barceló, C.; Jannes, G.; Sánchez-Dehesa, J.; Martínez, A.

    2013-01-01

    Transformation optics has shaped up a revolutionary electromagnetic design paradigm, enabling scientists to build astonishing devices such as invisibility cloaks. Unfortunately, the application of transformation techniques to other branches of physics is often constrained by the structure of the field equations. We develop here a complete transformation method using the idea of analogue spacetimes. The method is general and could be considered as a new paradigm for controlling waves in different branches of physics, from acoustics in quantum fluids to graphene electronics. As an application, we derive an “analogue transformation acoustics” formalism that naturally allows the use of transformations mixing space and time or involving moving fluids, both of which were impossible with the standard approach. To demonstrate the power of our method, we give explicit designs of a dynamic compressor, a spacetime cloak for acoustic waves and a carpet cloak for a moving aircraft. PMID:23774575

  15. Analogue transformations in physics and their application to acoustics.

    PubMed

    García-Meca, C; Carloni, S; Barceló, C; Jannes, G; Sánchez-Dehesa, J; Martínez, A

    2013-01-01

    Transformation optics has shaped up a revolutionary electromagnetic design paradigm, enabling scientists to build astonishing devices such as invisibility cloaks. Unfortunately, the application of transformation techniques to other branches of physics is often constrained by the structure of the field equations. We develop here a complete transformation method using the idea of analogue spacetimes. The method is general and could be considered as a new paradigm for controlling waves in different branches of physics, from acoustics in quantum fluids to graphene electronics. As an application, we derive an "analogue transformation acoustics" formalism that naturally allows the use of transformations mixing space and time or involving moving fluids, both of which were impossible with the standard approach. To demonstrate the power of our method, we give explicit designs of a dynamic compressor, a spacetime cloak for acoustic waves and a carpet cloak for a moving aircraft.

  16. Analogue transformations in physics and their application to acoustics.

    PubMed

    García-Meca, C; Carloni, S; Barceló, C; Jannes, G; Sánchez-Dehesa, J; Martínez, A

    2013-01-01

    Transformation optics has shaped up a revolutionary electromagnetic design paradigm, enabling scientists to build astonishing devices such as invisibility cloaks. Unfortunately, the application of transformation techniques to other branches of physics is often constrained by the structure of the field equations. We develop here a complete transformation method using the idea of analogue spacetimes. The method is general and could be considered as a new paradigm for controlling waves in different branches of physics, from acoustics in quantum fluids to graphene electronics. As an application, we derive an "analogue transformation acoustics" formalism that naturally allows the use of transformations mixing space and time or involving moving fluids, both of which were impossible with the standard approach. To demonstrate the power of our method, we give explicit designs of a dynamic compressor, a spacetime cloak for acoustic waves and a carpet cloak for a moving aircraft. PMID:23774575

  17. Long-Lived, Sub-Surface Layers of Toxic Oil in the Deep-Sea: A Molecular Organic and Isotopic Geochemical Approach to Understanding their Nature, Molecular Distribution, Origin and Impact to the Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Hollander, D. J.; Freeman, K. H.; Ellis, G.; Diefendorf, A. F.; Peebles, E. B.; Paul, J.

    2010-12-01

    Here we present the results from two research cruises to the Northern Gulf of Mexico (GoM) during May and August 2010, after the April 20th blowout of BP’s Deepwater Horizon (DWH) drilling rig. Not only was the DWH tragedy the largest oil spill to have ever occurred in the United States but it was also the first blowout of a deep-sea oil exploration well. The BP oil spill presents the scientific community with a critically important and unique opportunity: i) to characterize the occurrence, molecular distribution and abundance of the hydrocarbons in the sub-surface, ii) to identify the source of the oil in the environment and, iii) to study how the distribution and chemistry of the hydrocarbons change over time and space and whether the sub-surface hydrocarbons are toxic to marine plankton and bacteria. Using sonar, fluorometry and backscatter, we were able to trace the occurrence of layers of sub-surface oil. These oil layers were found suspended at depths of 400 m and 1000-1400 m in the form of small microdroplets that were not visible to the naked eye. Both the 400 and the 1000 m layers were traced for more than 20 miles in length and 4 miles in width. Molecular organic geochemical analyses determined that petroleum hydrocarbons were the dominant components of the 400 and 1000 m layers. Interesting, the distribution of compounds was extremely consistent among all the samples with n-alkanes ranging from C24 to C37 with a maximum at C28. The loss of the lower molecular weight components of the crude oil is attributed to biodegradation. This distribution of n-alkanes was the same regardless of whether the samples were from 400 or 1000 m, whether the sites were 25 or 45 miles from the DWH site or whether the samples were collected in May or August. These observations strongly suggest that the bacteria are not able to consume all of the oil, and that these higher molecular weight compounds may persist in the environment for extended lengths of time, at least months

  18. Habitability & Astrobiology Research in Mars Terrestrial Analogues

    NASA Astrophysics Data System (ADS)

    Foing, Bernard

    2014-05-01

    We performed a series of field research campaigns (ILEWG EuroMoonMars) in the extreme Utah desert relevant to Mars environments, and in order to help in the interpretation of Mars missions measurements from orbit (MEX, MRO) or from the surface (MER, MSL), or Moon geochemistry (SMART-1, LRO). We shall give an update on the sample analysis in the context of habitability and astrobiology. Methods & Results: In the frame of ILEWG EuroMoonMars campaigns (2009 to 2013) we deployed at Mars Desert Research station, near Hanksville Utah, a suite of instruments and techniques [A, 1, 2, 9-11] including sample collection, context imaging from remote to local and microscale, drilling, spectrometers and life sensors. We analyzed how geological and geochemical evolution affected local parameters (mineralogy, organics content, environment variations) and the habitability and signature of organics and biota. Among the important findings are the diversity in the composition of soil samples even when collected in close proximity, the low abundances of detectable PAHs and amino acids and the presence of biota of all three domains of life with significant heterogeneity. An extraordinary variety of putative extremophiles was observed [3,4,9]. A dominant factor seems to be soil porosity and lower clay-sized particle content [6-8]. A protocol was developed for sterile sampling, contamination issues, and the diagnostics of biodiversity via PCR and DGGE analysis in soils and rocks samples [10, 11]. We compare the 2009 campaign results [1-9] to new measurements from 2010-2013 campaigns [10-12] relevant to: comparison between remote sensing and in-situ measurements; the study of minerals; the detection of organics and signs of life. Keywords: field analogue research, astrobiology, habitability, life detection, Earth-Moon-Mars, organics References [A] Foing, Stoker & Ehrenfreund (Editors, 2011) "Astrobiology field Research in Moon/Mars Analogue Environments", Special Issue of International

  19. Exploring functional cyclophellitol analogues as human retaining beta-glucosidase inhibitors.

    PubMed

    Li, Kah-Yee; Jiang, Jianbing; Witte, Martin D; Kallemeijn, Wouter W; Donker-Koopman, Wilma E; Boot, Rolf G; Aerts, Johannes M F G; Codée, Jeroen D C; van der Marel, Gijsbert A; Overkleeft, Herman S

    2014-10-21

    The natural product, cyclophellitol and its aziridine analogue are potent mechanism-based retaining β-glucosidase inhibitors. In this paper we explore the inhibitory potency of a number of cyclophellitol analogues against the three human retaining β-glucosidases, GBA, GBA2 and GBA3. We demonstrate that N-alkyl cyclophellitol aziridine is at least equally potent in inhibiting the enzymes evaluated as its N-acyl congener, whereas the N-sulfonyl analogue is a considerably weaker inhibitor. Our results complement the literature on the inhibitory potency of cyclophellitol analogues and hold promise for the future design of more effective activity-based retaining glycosidase probes with respect to probe stability in physiological media.

  20. Deep-fault connection characterization from combined field and geochemical methodology; examples from Green River and Haiti fault systems

    NASA Astrophysics Data System (ADS)

    Nadine, E. Z.; Frery, E.; Leroy, S.; Mercier De Lepinay, B. F.; Momplaisir, R.

    2011-12-01

    widening of the impacted zones indicating a strong partitioning of the deformation. The resulting stress re-location is well expressed by (1) the dispersion of the aftershocks, essentially North of the strike-slip fault, (2) a progressive local uplift on the hanging wall, and (3) by along-fault fluid flow variation (leaking segments) either along the EPGF recently active segments but also around the Cul-de-Sac plain. As a first approach, we focus our attention on fault-related fluid leakage distribution, located at intersection points between strike-slip and compressive faults. Using this combined approach, mixing structural and geochemical analytical work, we will hopefully be able (i) to identify the transient and permanent fault activity, and (ii) to characterize the time recurrence (if any) and (iii) the location of the seismic activity during the Quaternary in this two natural analogues.

  1. Predictive Radiological Background Distributions from Geochemical Data

    NASA Astrophysics Data System (ADS)

    Haber, D.; Burnley, P. C.; Marsac, K.; Malchow, R.

    2014-12-01

    Gamma ray surveys are an important tool for both national security interests as well as industry in determininglocations of both anthropogenic radiological sources and natural occurrences of radiologic material. The purpose ofthis project is to predict the radiologic exposure rate of geologic materials by creating a model using publishedgeochemical data, geologic data, GIS software, and freely available remote sensing data sets. If K, U, and Thabundance values are known for a given geologic unit, the expected radiation exposure rate can be calculated. Oneof the primary challenges surrounding this project is that alluvial units are classified by age rather than rock type. Itis therefore important to determine sediment sources and estimate their relative contribution to alluvial units.ASTER data from the Terra satellite can differentiate between surface mineralogies and can aid us in calculating therelative percentage of sediment from each source and by extension the geochemical concentrations of challengingsurfaces such as alluvium. An additional problem is that U and Th do not directly contribute to the measuredradiation exposure rate. Instead, daughter isotopes of these radioelements emit detectable gamma rays and may nothave reached equilibrium in younger surfaces. U can take up to 1.5 Ma to come to equilibrium with its daughterisotopes while Th takes only about 40 years. Further modeling with software such as Monte Carlo N-ParticleTransport from Los Alamos National Laboratory, will help us correct for this disequilibrium in our models. Once the predicted exposure rate is calculated for a geologic unit, it can then be assigned to a geographic area basedon geologic and geomorphic trends. This prediction will be subtracted from data collected through aerial surveys,effectively ignoring geology, and allowing areas of interest to be narrowed down considerably. The study areasinclude the alluvium on the west shore of Lake Mohave and Government Wash north of Lake Mead

  2. Fluorescent polyene ceramide analogues as membrane probes.

    PubMed

    Nieves, Ingrid; Artetxe, Ibai; Abad, José Luis; Alonso, Alicia; Busto, Jon V; Fajarí, Lluís; Montes, L Ruth; Sot, Jesús; Delgado, Antonio; Goñi, Félix M

    2015-03-01

    Three ceramide analogues have been synthesized, with sphingosine-like chains containing five conjugated double bonds. Pentaene I has an N-palmitoyl acyl chain, while the other two pentaenes contain also a doxyl radical, respectively, at C5 (Penta5dox) and at C16 (Penta16dox) positions of the N-acyl chain. Pentaene I maximum excitation and emission wavelengths in a phospholipid bilayer are 353 and 478 nm, respectively. Pentaene I does not segregate from the other lipids in the way natural ceramide does, but rather mixes with them in a selective way according to the lipid phases involved. Fluorescence confocal microscopy studies show that when lipid domains in different physical states coexist, Pentaene I emission is higher in gel than in fluid domains, and in liquid-ordered than in liquid-disordered areas. Electron paramagnetic resonance of the pentaene doxyl probes confirms that these molecules are sensitive to the physical state of the bilayer. Calorimetric and fluorescence quenching experiments suggest that the lipids under study orient themselves in lipid bilayers with their polar moieties located at the lipid-water interface. The doxyl radical in the N-acyl chain quenches the fluorescence of the pentaene group when in close proximity. Because of this property, Penta16dox can detect gel-fluid transitions in phospholipids. The availability of probes for lipids in the gel phase is important in view of novel evidence for the existence of gel microdomains in cell membranes.

  3. Identifying paleotsunami deposits in Thailand using geochemical analyses

    NASA Astrophysics Data System (ADS)

    Löwhagen, Linda; Jankaew, Kruawun; Kylander, Malin; Wohlfarth, Barbara

    2014-05-01

    Paleotsunami research has received considerable attention following the devastating Indian Ocean tsunami of December 2004. Specific questions involve the magnitude, frequency and impact of past tsunamis. Phra Thong Island in the eastern Andaman Sea is an ideal location to study paleotsunami deposits in great detail (Jankaew et al., 2008). Apart from the 2004 Indian Ocean tsunami layer, three more distinct tsunami layers, separated by soil horizons have been identified and dated (Jankaew et al., 2008). In a collaborative project between Stockholm University and Chulalongkorn University, four sites on Phra Thong Island were chosen for detailed geochemical studies and additional AMS 14C dating. Paleotsunami deposits at these sites can be seen as more or less distinct sand layers embedded between the peaty soils. Here we report the initial results of XRF core scanning and loss on ignition analysis, which are supplemented by new 14C dates. The XRF data sets show a good correlation between synchronous tsunami layers along a coast-inland transect. The geochemistry moreover suggests a change in source area for the oldest tsunami layer. Further work will focus on a detailed geochemical characterization of the tsunami and soil layers, and on the influence of soil processes on the geochemical record. Reference: Jankaew, K; Atwater, B; Sawai, Y; Choowong, M; Charoentitirat, T; Martin, M; Prendergast, A, 2008. Medieval forewarning of the 2004 Indian Ocean tsunami in Thailand. Nature 455, 1228-1231.

  4. Eastern Devonian shales: Organic geochemical studies, past and present

    USGS Publications Warehouse

    Breger, I.A.; Hatcher, P.G.; Romankiw, L.A.; Miknis, F.P.

    1983-01-01

    The Eastern Devonian shales are represented by a sequence of sediments extending from New York state, south to the northern regions of Georgia and Alabama, and west into Ohio and to the Michigan and Ilinois Basins. Correlatives are known in Texas. The shale is regionally known by a number of names: Chattanooga, Dunkirk, Rhinestreet, Huron, Antrim, Ohio, Woodford, etc. These shales, other than those in Texas, have elicited much interest because they have been a source of unassociated natural gas. It is of particular interest, however, that most of these shales have no associated crude oil, in spite of the fact that they have some of the characteristics normally attributed to source beds. This paper addresses some of the organic geochemical aspects of the kerogen in these shales, in relation to their oil generating potential. Past organic geochemical studies on Eastern Devonian shales will be reviewed. Recent solid state 13C NMR studies on the nature of the organic matter in Eastern Devonian shales show that Eastern Devonian shales contain a larger fraction of aromatic carbon in their chemical composition. Thus, despite their high organic matter contents, their potential as a petroleum source rock is low, because the kerogen in these shales is of a "coaly" nature and hence more prone to producing natural gas.

  5. Plant Volatile Analogues Strengthen Attractiveness to Insect

    PubMed Central

    Sun, Yufeng; Yu, Hao; Zhou, Jing-Jiang; Pickett, John A.; Wu, Kongming

    2014-01-01

    Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of β-ionone and benzaldehyde. The stabilities of β-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than β-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than β-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety. PMID:24911460

  6. Natural weathering of archaeo-metallurgical slags: an analog for present day vitrified wastesL'altération naturelle des scories de la métallurgie ancienne : un analogue de déchets vitrifiés

    NASA Astrophysics Data System (ADS)

    Mahé-Le Carlier, Cécile; Le Carlier de Veslud, Christian; Ploquin, Alain; Royer, Jean-Jacques

    2000-02-01

    The study of the natural alteration of ancient vitreous slags (100 to 4 000 years) suggests a single global mechanism. In a first stage, weathering consists of a selective extraction of the modifier cations of glass (including Pb and Ba). This phenomenon is associated with an increase of the solution pH, inducing the glass dissolution. The elements with a weak limit of solubility remain in place and can form hydroxides (Al, Fe). Pb and Ba are extracted from weathered glass. Pb is located in Fe-hydroxides, Ba may form sulfides. The rate of alteration varies from 20 to 180 μm per 1 000 years.

  7. Synthesis and biological evaluation of febrifugine analogues.

    PubMed

    Mai, Huong Doan Thi; Thanh, Giang Vo; Tran, Van Hieu; Vu, Van Nam; Vu, Van Loi; Le, Cong Vinh; Nguyen, Thuy Linh; Phi, Thi Dao; Truong, Bich Ngan; Chau, Van Minh; Pham, Van Cuong

    2014-12-01

    A series of febrifugine analogues were designed and synthesized. Antimalarial activity evaluation of the synthetic compounds indicated that these derivatives had a strong inhibition against both chloroquine-sensitive and -resistant Plasmodium falciparum parasites. Many of them were found to be more active than febrifugine hydrochloride. The tested analogues had also a significant cytotoxicity against four cancer cell lines (KB, MCF7, LU1 and HepG2). Among the synthetic analogues, two compounds 17b and 17h displayed a moderate cytotoxicity while they exhibited a remarkable antimalarial activity. PMID:25632466

  8. Geochemical Modeling Of Aqueous Systems

    1995-09-07

    EQ3/6 is a software package for geochemical modeling of aqueous systems. This description pertains to version 7.2b. It addresses aqueous speciation, thermodynamic equilibrium, disequilibrium, and chemical kinetics. The major components of the package are EQ3NR, a speciation-solubility code, and EQ6 a reaction path code. EQ3NR is useful for analyzing groundwater chemistry data, calculating solubility limits, and determining whether certain reactions are in states of equilibrium or disequilibrium. It also initializes EQ6 calculations. EQ6 models themore » consequences of reacting an aqueous solution with a specified set of reactants (e.g., minerals or waste forms). It can also model fluid mixing and the effects of changes in temperature. Each of five supporting data files contain both standard state and activity coefficient-related data. Three support the use of the Davies or B-dot equations for the activity coefficients; the other two support the use of Pitzer''s equations. The temperature range of the thermodynamic data on the data files varies from 25 degrees C only to 0-300 degrees C.« less

  9. Cerium and Neodymium Isotope Fractionation in Geochemical Samples

    NASA Astrophysics Data System (ADS)

    Ohno, T.; Ishibashi, T.

    2014-12-01

    The study of naturally occurring isotopic variations of rare earth elements (REE) has a potentially significant influence in geochemical research fields with other traditional studies of REE. One of the key features of REE are their chemical similarities and gradual changes of ionic radius, which may make the isotopic variation of REE a potential tool to understand the mechanisms of isotopic fractionation in nature. Among the REE, geochemical and physicochemical features of Ce could be anomalous, because Ce could be present as the tetravalent (+IV) state as well as the common trivalent (+III) state of other REE. Since the oxidation state of Ce can change by reflecting the redox conditions of the environment, the measured differences in the degree of isotopic fractionation between Ce and other REE can provide unique information about the redox conditions. In this study, we developed a new analytical method to determine the mass-dependent isotopic fractionations of Ce and Nd in geochemical samples. The reproducibility of the isotopic ratio measurements on 142Ce/140Ce, 146Nd/144Nd and 148Nd/144Nd were 0.08‰ (2SD, n=25), 0.06‰ (2SD, n=39) and 0.12‰ (2SD, n=39), respectively. The present technique was applied to determine the variations of the Ce and Nd isotopic ratios for five geochemical reference materials (igneous rocks, JB-1a and JA-2; sedimentary rocks, JMn-1, JCh-1 and JDo-1). The resulting ratios for two igneous rocks (JB-1a and JA-2) and two sedimentary rocks (JMn-1 and JCh-1) did not vary significantly among the samples, whereas the Ce and Nd isotope ratios for the carbonate samples (JDo-1) were significantly higher than those for igneous and sedimentary rock samples. The 1:1 simple correlation between δ142Ce and δ146Nd indicates that there were no significant difference in the degree of isotopic fractionation between the Ce and Nd. This suggests that the isotopic fractionation for Ce found in the JDo-1 could be induced by physicochemical processes

  10. Do film soundtracks contain nonlinear analogues to influence emotion?

    PubMed

    Blumstein, Daniel T; Davitian, Richard; Kaye, Peter D

    2010-12-23

    A variety of vertebrates produce nonlinear vocalizations when they are under duress. By their very nature, vocalizations containing nonlinearities may sound harsh and are somewhat unpredictable; observations that are consistent with them being particularly evocative to those hearing them. We tested the hypothesis that humans capitalize on this seemingly widespread vertebrate response by creating nonlinear analogues in film soundtracks to evoke particular emotions. We used lists of highly regarded films to generate a set of highly ranked action/adventure, dramatic, horror and war films. We then scored the presence of a variety of nonlinear analogues in these film soundtracks. Dramatic films suppressed noise of all types, contained more abrupt frequency transitions and musical sidebands, and fewer noisy screams than expected. Horror films suppressed abrupt frequency transitions and musical sidebands, but had more non-musical sidebands, and noisy screams than expected. Adventure films had more male screams than expected. Together, our results suggest that film-makers manipulate sounds to create nonlinear analogues in order to manipulate our emotional responses.

  11. Do film soundtracks contain nonlinear analogues to influence emotion?

    PubMed Central

    Blumstein, Daniel T.; Davitian, Richard; Kaye, Peter D.

    2010-01-01

    A variety of vertebrates produce nonlinear vocalizations when they are under duress. By their very nature, vocalizations containing nonlinearities may sound harsh and are somewhat unpredictable; observations that are consistent with them being particularly evocative to those hearing them. We tested the hypothesis that humans capitalize on this seemingly widespread vertebrate response by creating nonlinear analogues in film soundtracks to evoke particular emotions. We used lists of highly regarded films to generate a set of highly ranked action/adventure, dramatic, horror and war films. We then scored the presence of a variety of nonlinear analogues in these film soundtracks. Dramatic films suppressed noise of all types, contained more abrupt frequency transitions and musical sidebands, and fewer noisy screams than expected. Horror films suppressed abrupt frequency transitions and musical sidebands, but had more non-musical sidebands, and noisy screams than expected. Adventure films had more male screams than expected. Together, our results suggest that film-makers manipulate sounds to create nonlinear analogues in order to manipulate our emotional responses. PMID:20504815

  12. Stereochemical Assignment of Strigolactone Analogues Confirms Their Selective Biological Activity.

    PubMed

    Artuso, Emma; Ghibaudi, Elena; Lace, Beatrice; Marabello, Domenica; Vinciguerra, Daniele; Lombardi, Chiara; Koltai, Hinanit; Kapulnik, Yoram; Novero, Mara; Occhiato, Ernesto G; Scarpi, Dina; Parisotto, Stefano; Deagostino, Annamaria; Venturello, Paolo; Mayzlish-Gati, Einav; Bier, Ariel; Prandi, Cristina

    2015-11-25

    Strigolactones (SLs) are new plant hormones with various developmental functions. They are also soil signaling chemicals that are required for establishing beneficial mycorrhizal plant/fungus symbiosis. In addition, SLs play an essential role in inducing seed germination in root-parasitic weeds, which are one of the seven most serious biological threats to food security. There are around 20 natural SLs that are produced by plants in very low quantities. Therefore, most of the knowledge on SL signal transduction and associated molecular events is based on the application of synthetic analogues. Stereochemistry plays a crucial role in the structure-activity relationship of SLs, as compounds with an unnatural D-ring configuration may induce biological effects that are unrelated to SLs. We have synthesized a series of strigolactone analogues, whose absolute configuration has been elucidated and related with their biological activity, thus confirming the high specificity of the response. Analogues bearing the R-configured butenolide moiety showed enhanced biological activity, which highlights the importance of this stereochemical motif. PMID:26502774

  13. Do film soundtracks contain nonlinear analogues to influence emotion?

    PubMed

    Blumstein, Daniel T; Davitian, Richard; Kaye, Peter D

    2010-12-23

    A variety of vertebrates produce nonlinear vocalizations when they are under duress. By their very nature, vocalizations containing nonlinearities may sound harsh and are somewhat unpredictable; observations that are consistent with them being particularly evocative to those hearing them. We tested the hypothesis that humans capitalize on this seemingly widespread vertebrate response by creating nonlinear analogues in film soundtracks to evoke particular emotions. We used lists of highly regarded films to generate a set of highly ranked action/adventure, dramatic, horror and war films. We then scored the presence of a variety of nonlinear analogues in these film soundtracks. Dramatic films suppressed noise of all types, contained more abrupt frequency transitions and musical sidebands, and fewer noisy screams than expected. Horror films suppressed abrupt frequency transitions and musical sidebands, but had more non-musical sidebands, and noisy screams than expected. Adventure films had more male screams than expected. Together, our results suggest that film-makers manipulate sounds to create nonlinear analogues in order to manipulate our emotional responses. PMID:20504815

  14. Singularity analysis based on wavelet transform of fractal measures for identifying geochemical anomaly in mineral exploration

    NASA Astrophysics Data System (ADS)

    Chen, Guoxiong; Cheng, Qiuming

    2016-02-01

    Multi-resolution and scale-invariance have been increasingly recognized as two closely related intrinsic properties endowed in geofields such as geochemical and geophysical anomalies, and they are commonly investigated by using multiscale- and scaling-analysis methods. In this paper, the wavelet-based multiscale decomposition (WMD) method was proposed to investigate the multiscale natures of geochemical pattern from large scale to small scale. In the light of the wavelet transformation of fractal measures, we demonstrated that the wavelet approximation operator provides a generalization of box-counting method for scaling analysis of geochemical patterns. Specifically, the approximation coefficient acts as the generalized density-value in density-area fractal modeling of singular geochemical distributions. Accordingly, we presented a novel local singularity analysis (LSA) using the WMD algorithm which extends the conventional moving averaging to a kernel-based operator for implementing LSA. Finally, the novel LSA was validated using a case study dealing with geochemical data (Fe2O3) in stream sediments for mineral exploration in Inner Mongolia, China. In comparison with the LSA implemented using the moving averaging method the novel LSA using WMD identified improved weak geochemical anomalies associated with mineralization in covered area.

  15. Antimicrobial activity of resveratrol analogues.

    PubMed

    Chalal, Malik; Klinguer, Agnès; Echairi, Abdelwahad; Meunier, Philippe; Vervandier-Fasseur, Dominique; Adrian, Marielle

    2014-01-01

    Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold). The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups) and antimicrobial activity. PMID:24918540

  16. Space analogue studies in Antarctica.

    PubMed

    Lugg, D; Shepanek, M

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  17. Antimicrobial activity of resveratrol analogues.

    PubMed

    Chalal, Malik; Klinguer, Agnès; Echairi, Abdelwahad; Meunier, Philippe; Vervandier-Fasseur, Dominique; Adrian, Marielle

    2014-06-10

    Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold). The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups) and antimicrobial activity.

  18. Space analogue studies in Antarctica

    NASA Technical Reports Server (NTRS)

    Lugg, D.; Shepanek, M.

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  19. Space analogue studies in Antarctica

    NASA Astrophysics Data System (ADS)

    Lugg, D.; Shepanek, M.

    1999-09-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mltogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  20. Evaluation of Anti-HIV-1 Mutagenic Nucleoside Analogues*

    PubMed Central

    Vivet-Boudou, Valérie; Isel, Catherine; El Safadi, Yazan; Smyth, Redmond P.; Laumond, Géraldine; Moog, Christiane; Paillart, Jean-Christophe; Marquet, Roland

    2015-01-01

    Because of their high mutation rates, RNA viruses and retroviruses replicate close to the threshold of viability. Their existence as quasi-species has pioneered the concept of “lethal mutagenesis” that prompted us to synthesize pyrimidine nucleoside analogues with antiviral activity in cell culture consistent with an accumulation of deleterious mutations in the HIV-1 genome. However, testing all potentially mutagenic compounds in cell-based assays is tedious and costly. Here, we describe two simple in vitro biophysical/biochemical assays that allow prediction of the mutagenic potential of deoxyribonucleoside analogues. The first assay compares the thermal stabilities of matched and mismatched base pairs in DNA duplexes containing or not the nucleoside analogues as follows. A promising candidate should display a small destabilization of the matched base pair compared with the natural nucleoside and the smallest gap possible between the stabilities of the matched and mismatched base pairs. From this assay, we predicted that two of our compounds, 5-hydroxymethyl-2′-deoxyuridine and 5-hydroxymethyl-2′-deoxycytidine, should be mutagenic. The second in vitro reverse transcription assay assesses DNA synthesis opposite nucleoside analogues inserted into a template strand and subsequent extension of the newly synthesized base pairs. Once again, only 5-hydroxymethyl-2′-deoxyuridine and 5-hydroxymethyl-2′-deoxycytidine are predicted to be efficient mutagens. The predictive potential of our fast and easy first line screens was confirmed by detailed analysis of the mutation spectrum induced by the compounds in cell culture because only compounds 5-hydroxymethyl-2′-deoxyuridine and 5-hydroxymethyl-2′-deoxycytidine were found to increase the mutation frequency by 3.1- and 3.4-fold, respectively. PMID:25398876

  1. Projected Future Climate Analogues and Climate "Velocities" in North America

    NASA Astrophysics Data System (ADS)

    Shafer, S. L.; Bartlein, P. J.

    2014-12-01

    Future climate changes may have significant effects on many North American ecosystems. One way of assessing the potential impacts of future climate change is to use future climate analogues of present climate to evaluate the spatial extent and rates of future climate change. We used a set of Coupled Model Intercomparison Project phase 5 (CMIP5) coupled atmosphere-ocean general circulation model (AOGCM) future climate simulations (2006-2100) produced under representative concentration pathway scenario RCP8.5. We regridded these data to a 10-km equal-area grid of North America. Modern climate data (1961-1990 30-year mean) were interpolated to the same 10-km grid. The projected future climate data were analyzed using 10-year mean values of monthly and seasonal temperature and precipitation and a set of derived annual bioclimatic variables (e.g., growing degree days) considered to be ecologically significant. Potential future climate analogues were calculated for each grid cell using Euclidean distances to identify similar climates occurring elsewhere in North America. We identify regions that are projected to retain climates similar to present in the future (e.g., parts of the southeastern United States) and regions where present climates are projected to become less common or to disappear in the future (e.g., high elevation sites in western North America). We also calculate the rates of change in locations of similar climates (i.e., climate analogue velocities) and compare our results with simulated paleoclimate velocities over the past 22 kyr (from TraCE-21ka transient climate simulations for 22 ka-present). We discuss the implications of these results for conservation and natural resource management in North America. We also describe a web application being developed to allow researchers, decision makers, and members of the public, to visualize, explore, and use the climate analogue data.

  2. Dimerization and DNA recognition rules of mithramycin and its analogues.

    PubMed

    Weidenbach, Stevi; Hou, Caixia; Chen, Jhong-Min; Tsodikov, Oleg V; Rohr, Jürgen

    2016-03-01

    The antineoplastic and antibiotic natural product mithramycin (MTM) is used against cancer-related hypercalcemia and, experimentally, against Ewing sarcoma and lung cancers. MTM exerts its cytotoxic effect by binding DNA as a divalent metal ion (Me(2+))-coordinated dimer and disrupting the function of transcription factors. A precise molecular mechanism of action of MTM, needed to develop MTM analogues selective against desired transcription factors, is lacking. Although it is known that MTM binds G/C-rich DNA, the exact DNA recognition rules that would allow one to map MTM binding sites remain incompletely understood. Towards this goal, we quantitatively investigated dimerization of MTM and several of its analogues, MTM SDK (for Short side chain, DiKeto), MTM SA-Trp (for Short side chain and Acid), MTM SA-Ala, and a biosynthetic precursor premithramycin B (PreMTM B), and measured the binding affinities of these molecules to DNA oligomers of different sequences and structural forms at physiological salt concentrations. We show that MTM and its analogues form stable dimers even in the absence of DNA. All molecules, except for PreMTM B, can bind DNA with the following rank order of affinities (strong to weak): MTM=MTM SDK>MTM SA-Trp>MTM SA-Ala. An X(G/C)(G/C)X motif, where X is any base, is necessary and sufficient for MTM binding to DNA, without a strong dependence on DNA conformation. These recognition rules will aid in mapping MTM sites across different promoters towards development of MTM analogues as useful anticancer agents.

  3. Principles of landscape-geochemical studies in the zones contaminated by technogenical radionuclides for ecological and geochemical mapping

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Romanov, Sergey

    2013-04-01

    Efficiency of landscape-geochemical approach was proved to be helpful in spatial and temporal evaluation of the Chernobyl radionuclide distribution in the environment. The peculiarity of such approach is in hierarchical consideration of factors responsible for radionuclide redistribution and behavior in a system of inter-incorporated landscape-geochemical structures of the local and regional scales with due regard to the density of the initial fallout and patterns of radionuclide migration in soil-water-plant systems. The approach has been applied in the studies of distribution of Cs-137, Sr-90 and some other radionuclides in soils and vegetation cover and in evaluation of contribution of the stable iodine supply in soils to spatial variation of risk of thyroid cancer in areas subjected to radioiodine contamination after the Chernobyl accident. The main feature of the proposed approach is simultaneous consideration of two types of spatial heterogeneities: firstly, the inhomogeneity of external radiation exposure due to a complex structure of the contamination field, and, secondly, the landscape geochemical heterogeneity of the affected area, so that the resultant effect of radionuclide impact could significantly vary in space. The main idea of risk assessment in this respect was to reproduce as accurately as possible the result of interference of two surfaces in the form of risk map. The approach, although it demands to overcome a number of methodological difficulties, allows to solve the problems associated with spatially adequate protection of the affected population and optimization of the use of contaminated areas. In general it can serve the basis for development of the idea of the two-level structure of modern radiobiogeochemical provinces formed by superposition of the natural geochemical structures and the fields of technogenic contamination accompanied by the corresponding peculiar and integral biological reactions.

  4. The National Geochemical Survey; database and documentation

    USGS Publications Warehouse

    ,

    2004-01-01

    The USGS, in collaboration with other federal and state government agencies, industry, and academia, is conducting the National Geochemical Survey (NGS) to produce a body of geochemical data for the United States based primarily on stream sediments, analyzed using a consistent set of methods. These data will compose a complete, national-scale geochemical coverage of the US, and will enable construction of geochemical maps, refine estimates of baseline concentrations of chemical elements in the sampled media, and provide context for a wide variety of studies in the geological and environmental sciences. The goal of the NGS is to analyze at least one stream-sediment sample in every 289 km2 area by a single set of analytical methods across the entire nation, with other solid sample media substituted where necessary. The NGS incorporates geochemical data from a variety of sources, including existing analyses in USGS databases, reanalyses of samples in USGS archives, and analyses of newly collected samples. At the present time, the NGS includes data covering ~71% of the land area of the US, including samples in all 50 states. This version of the online report provides complete access to NGS data, describes the history of the project, the methodology used, and presents preliminary geochemical maps for all analyzed elements. Future editions of this and other related reports will include the results of analysis of variance studies, as well as interpretive products related to the NGS data.

  5. Sulfur analogues of psychotomimetic agents. Monothio analogues of mescaline and isomescaline.

    PubMed

    Jacob, P; Shulgin, A T

    1981-11-01

    Two monothio analogues of mescaline and three monothio analogues of 2,3,4-trimethoxyphenethylamine (isomescaline) have been synthesized and characterized. Only the two mescaline analogues (3-and 4-thiomescaline) were found to be psychotomimetics in man, being 6 and 12 times more potent than mescaline, respectively. All five compounds can serve as substrates for bovine plasma monoamine oxidase in vitro, but no positive correlation is apparent between the extent of enzymatic degradation and human psychotomimetic potency.

  6. Phosphorous-containing analogues of aspartame.

    PubMed

    Nelson, V; Mastalerz, P

    1984-12-01

    Four analogues of aspartame (aspartylphenylalanine methyl ester) were prepared in which one of the carboxylate groups was replaced by a phosphonate group. None of the peptides so obtained was sweet, in contrast with the parent compound which is over 100 times sweeter than sucrose. These results contrast with several published reports of phosphonate analogues of amino acids and peptides which are potent inhibitors of enzymes containing acceptor sites for the parent compound.

  7. Natural and enhanced attenuation of metals

    SciTech Connect

    Rouse, J.V.; Pyrih, R.Z.

    1996-12-31

    The ability of natural earthen materials to attenuate the movement of contamination can be quantified in relatively simple geochemical experiments. In addition, the ability of subsurface material to attenuate potential contaminants can be enhanced through modifications to geochemical parameters such as pH or redox conditions. Such enhanced geochemical attenuation has been demonstrated at a number of sites to be a cost-effective alternative to conventional pump and treat operations. This paper describes the natural attenuation reactions which occur in the subsurface, and the way to quantify such attenuation. It also introduces the concept of enhanced geochemical attenuation, wherein naturally-occurring geochemical reactions can be used to achieve in situ fixation. The paper presents examples where such natural and enhanced attenuation have been implemented as a part of an overall remedy.

  8. Naphthyl- and quinolylluciferin: green and red light emitting firefly luciferin analogues.

    PubMed

    Branchini, B R; Hayward, M M; Bamford, S; Brennan, P M; Lajiness, E J

    1989-05-01

    In the course of investigations on the possible involvement of the CIEEL (chemically initiated electron-exchange luminescence) mechanism in firefly bioluminescence, we have synthesized two novel firefly luciferin substrate analogues. D-Naphthylluciferin and D-quinolylluciferin were prepared by condensing D-cysteine with 2-cyano-6-hydroxynaphthalene and 2-cyano-6-hydroxyquinoline, respectively. These analogues are the first examples of bioluminescent substrates for firefly luciferase that do not contain a benzothiazole moiety. Firefly luciferase-catalyzed bioluminescence emission spectra revealed that compared to the normal yellow-green light of luciferin (lambda max = 559 nm), the emission from naphthylluciferin is significantly blue-shifted (lambda max = 524 nm); whereas quinolylluciferin emits orange-red light (lambda max = 608 nm). The fluorescence emission spectra, reaction pH optima, relative light yields, light emission kinetics and KM values of the analogues also were measured and compared to those of luciferin. Neither of the analogues produced the characteristic flash kinetics observed for the natural substrate. Instead, slower rise times to peak emission intensity were recorded. It appears that the formation of an intermediate from the analogue adenylates prior to the addition of oxygen is responsible for the slow rise times. The synthetic substrate analogues described here should be useful for future mechanistic studies.

  9. Appalachian basin oil and natural gas: stratigraphic framework, total petroleum systems, and estimated ultimate recovery: Chapter C.1 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    USGS Publications Warehouse

    Ryder, Robert T.; Milici, Robert C.; Swezey, Christopher S.; Trippi, Michael H.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    The most recent U.S. Geological Survey (USGS) assessment of undiscovered oil and gas resources of the Appalachian basin was completed in 2002 (Milici and others, 2003). This assessment was based on the total petroleum system (TPS), a concept introduced by Magoon and Dow (1994) and developed during subsequent studies such as those by the U.S. Geological Survey World Energy Assessment Team (2000) and by Biteau and others (2003a,b). Each TPS is based on specific geologic elements that include source rocks, traps and seals, reservoir rocks, and the generation and migration of hydrocarbons. This chapter identifies the TPSs defined in the 2002 Appalachian basin oil and gas assessment and places them in the context of the stratigraphic framework associated with regional geologic cross sections D–D′ (Ryder and others, 2009, which was re-released in this volume, chap. E.4.1) and E–E′ (Ryder and others, 2008, which was re-released in this volume, chap. E.4.2). Furthermore, the chapter presents a recent estimate of the ultimate recoverable oil and natural gas in the basin.

  10. Organic geochemical constraints on paleoelevation

    NASA Astrophysics Data System (ADS)

    Polissar, P. J.; Rowley, D. B.; Currie, B. S.; Freeman, K. H.

    2012-12-01

    The elevation history of the land surface is an important factor in the interpretation of past tectonic, climate and ecological processes. However, quantitative estimates of paleoelevation are difficult to produce and new techniques are needed. Organic geochemical approaches to quantifying paleoelevations provide a new perspective on this difficult task. The hydrogen isotopic composition of organic biomarker molecules synthesized by plants and algae is systematically related to the water used for growth. Organic molecules in ancient sediments can provide values for the isotopic composition of this water and thus elevation, provided the relationship between elevation and isotopic values is known. Molecular hydrogen isotope ratios from Cenozoic lake sediments on the Tibetan Plateau demonstrate the utility of a biomarker approach. Terrestrial plant-wax D/H values on Neogene sediments from the Namling-Oiyug Basin provide new paleoelevation estimates that compare well with previous studies. Plant wax D/H ratios paired with lacustrine carbonate oxygen isotope values from the Lunpola and Hoh-Xil basins illustrate how paired isotope systems can unravel the isotopic composition of precipitation from evaporative enrichment of lake waters. A potentially fruitful avenue for future research is illustrated by D/H analyses on older sediments from the Namling-Oiyug Basin. These sediments—like many that could be useful for paleoaltimetry—have experienced significant burial and heating. As temperatures approach the oil window it becomes possible to exchange hydrogen in both the extractable organic molecules (bitumen) and the insoluble organic residue (kerogen). The extent to which this exchange alters the original isotopic composition will determine the usefulness of D/H analyses on thermally mature organic matter. The potential payoff and pitfalls of D/H analyses on heated sediments is illustrated with thermally immature and mature samples from the Namling-Oiyug Basin.

  11. Discodermolide analogues as the chemical component of combination bacteriolytic therapy.

    PubMed

    Smith, Amos B; Freeze, B Scott; LaMarche, Matthew J; Sager, Jason; Kinzler, Kenneth W; Vogelstein, Bert

    2005-08-01

    The marine natural product (+)-discodermolide (1) and several simplified analogues of this microtubule-stabilizing agent have proven to be potent in vitro cell growth inhibitory agents in several human cancer cell lines. Here, we demonstrate the in vivo efficacy of discodermolide and several simplified congeners, both as stand-alone anti-tumor agents and, in the case of (+)-2,3-anhydrodiscodermolide (3), as a chemical component of the combination bacteriolytic therapy. A single intravenous injection of (+)-3 plus genetically modified Clostridium novyi-NT spores caused rapid and complete regressions of tumors in mice bearing HCT116 colorectal cancer xenografts.

  12. Low-density geochemical mapping and the robustness of geochemical patterns

    USGS Publications Warehouse

    Smith, D.B.; Reimann, C.

    2008-01-01

    Geochemical mapping of entire continents and, ultimately, the world is still a challenge for applied geochemists. At sample densities traditionally used for geochemical exploration (1 site per 1-25 km2), geochemical mapping of whole continents is logistically extremely demanding and tremendously expensive. The first low-density geochemical surveys (1 site per 200 km2) were carried out during the late 1960s in Africa. Later surveys conducted in various parts of the world had sample densities ranging from 1 site per 300 km2 to 1 site per 18 000 km2. Although these surveys were deemed successful by the investigators in defining variations in background element content on a regional scale, the scientific community was sceptical that low-density geochemical mapping was possible and would provide useful information. The main area of criticism centred around the concern that at such low sample densities the resulting maps would not be robust, i.e. if the same area were resampled and remapped, different geochemical patterns would emerge. Different examples from the USA, Europe, China and Africa demonstrate that low-density geochemical mapping will result in stable and robust geochemical patterns at the continental scale. Such maps are urgently needed for a wide variety of applications. ?? 2008 AAG/ Geological Society of London.

  13. Geochemical Interactions and Viral-Prokaryote Relationships in Freshwater Environments

    NASA Astrophysics Data System (ADS)

    Kyle, J. E.; Ferris, G.

    2009-05-01

    Viral and prokaryotic abundances were surveyed throughout southern Ontario aquatic habitats to determine relationships with geochemical parameters in the natural environment. Surface water samples were collected from acid mine drainage in summer of 2007 and 2008 and from circum-neutral pH environments in October to November 2008. Site determination was based on collecting samples from various aquatic habitats (acid mine drainage, lakes, rivers, tributaries, wetlands) with differing bedrock geology (limestone and shale dominated vs granitic Canadian Shield) to obtain a range of geochemical conditions. At each site, measurements of temperature, pH, and Eh were conducted. Samples collected for microbial counts and electron imaging were preserved to a final concentration of 2.5 % (v/v) glutaraldehyde. Additional sample were filtered into 60 mL nalgene bottles and amber EPA certified 40 mL glass vials to determine chemical constituents and dissolved organic carbon (DOC), respectively. Water was also collected to determine additional physiochemical parameters (dissolved total iron, ferric iron, nitrate, sulfate, phosphate, alkalinity, and turbidity). All samples were stored at 4 °C until analysis. Viral and prokaryotic abundance was determined by staining samples with SYBR Green I and examining with a epifluorescence microscope under blue excitation. Multiple regression analysis using stepwise backwards regression and general linear models revealed that viral abundance was the most influential predictor of prokaryotic abundance. Additional predictors include pH, sulfate, phosphate, and magnesium. The strength of the model was very strong with 90 % of the variability explained (R2 = 0.90, p < 0.007). This is the first report, to our knowledge, of viruses exhibiting such strong controls over prokaryotic abundance in the natural environment. All relationships are positively correlated with the exception of Mg, which is negatively correlated. Iron was also noted as a

  14. Nano-FTIR for Geochemical Sample Analysis

    NASA Astrophysics Data System (ADS)

    Dominguez, G.; McCleod, A.; Gainsforth, Z.; Keilmann, F.; Westphal, A.; Thiemens, M. H.; Basov, D.

    2014-12-01

    Infrared (IR) spectroscopy is considered by many to be the "gold standard" for chemical identification, providing a direct connection between chemical compounds found in the laboratory and those found in natural samples including remote astrophysical environments. However, a well known limitation of using conventional IR spectroscopy is its spatial resolution determined by the wavelength of IR photons. Thus, while other techniques such as XANES and micro-Raman are capable of limited functional group mapping at tens to hundreds of nanometers, their use is limited by accessibility (the need for synchrotron beamlines) or the need for intense irradiation conditions (Raman) that can lead to sample alteration. These limitations and the wealth of information that can be extracted from detailed studies of unique micron-sized samples brought back by recent sample return missions such as NASA's Stardust mission, have motivated the development of a novel infrared mapping technique that is capable of mapping the chemical functional properties of geochemical samples with submicron resolutions. Here we describe our nano-FTIR imaging and analysis technique that allows us to bypass diffraction limited sample imaging in the infrared. Here we show, for the first time, that 1) the combination of an atomic-force microscope (AFM) and laser can be used to obtain the FTIR-equivalent spectra on spatial scales that are much smaller than the wavelength of IR radiation used 2) this technique responds to subtle shifts in cation concentrations as evidenced by changes in the frequencies of phonons at sub-micron scales 3) this technique can be used to identify regions of crystalline and semi-crystalline materials as demonstrated in our analysis of a cometary dust grain Iris. This work has clear implications for interpretations of astronomical observations and adds a new technique for the non-destructive characterization of terrestrial and extraterrestrial samples.

  15. Geologic and geochemical studies of the New Albany Shale Group (Devonian-Mississippian) in Illinois. Final report

    SciTech Connect

    Bergstrom, R.E.; Shimp, N.F.

    1980-06-30

    The Illinois State Geological Survey is conducting geological and geochemical investigations to evaluate the potential of New Albany Group shales as a source of hydrocarbons, particularly natural gas. Geological studies include stratigraphy and structure, mineralogic and petrographic characterization; analyses of physical properties; and development of a computer-based resources evaluation system. Geochemical studies include organic carbon content and trace elements; hydrocarbon content and composition; and adsorption/desorption studies of gas through shales. Separate abstracts have been prepared for each task reported.

  16. Presence of cobalamin analogues in animal tissues

    PubMed Central

    Kondo, Haruki; Kolhouse, Fred; Allen, Robert H.

    1980-01-01

    Cobalamin (Cbl, vitamin B-12) has been extracted and isolated from a number of animal tissues by using (i) reverse-affinity chromatography on R protein-Sepharose followed by adsorption to and elution from charcoal-coated agarose and (ii) paper chromatography. Radioisotope dilution assays showed that only 75-97% of the Cbl chromatographed in the position of crystalline Cbl. The remaining 3-25% was present in a number of slower and faster moving fractions. This suggested that Cbl analogues are present in animal tissues because appropriate controls ruled out the possibility that this material was artifactually derived from Cbl during the extraction and purification procedures. With a large-scale isolation from rabbit kidney, the material in five such fractions contained cobalt and had absorption spectra that were similar to but different from the spectrum of Cbl, indicating that they were Cbl analogues. Compared to Cbl, these Cbl analogues had decreased but definite affinities for Cbl-binding proteins with the following order of strength of binding: R protein > transcobalamin II > intrinsic factor. Compared to Cbl, they also had decreased but definite growth-promoting activity for two microorganisms, Euglena gracilis and Lactobacillus leichmannii, which require Cbl for growth. These Cbl analogues differed from each other and from 18 synthetic Cbl analogues, including the most common Cbl analogues synthesized by microorganisms, in at least one of the above features. These studies indicate that animal tissues contain a number of Cbl analogues whose origins, structures, and biologic activities remain to be determined. PMID:6928681

  17. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates

    NASA Astrophysics Data System (ADS)

    Atchley, Adam L.; Navarre-Sitchler, Alexis K.; Maxwell, Reed M.

    2014-09-01

    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb2 +) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb2 + concentrations within the plume. Dissimilarities between ensemble Pb2 + concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb2 + concentrations are the same for all three

  18. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates.

    PubMed

    Atchley, Adam L; Navarre-Sitchler, Alexis K; Maxwell, Reed M

    2014-09-01

    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb(2+)) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb(2+) concentrations within the plume. Dissimilarities between ensemble Pb(2+) concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb(2+) concentrations are the same for all

  19. The Canadian Analogue Research Network (CARN): Opportunities for Mars Analogue Studies in the Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Osinski, G. R.; Berinstain, A.; Lebeuf, M.; Léveillé, R.

    2006-10-01

    The Canadian Analogue Research Network has been established by the Canadian Space Agency. This network of analogue sites, many of which are in the Arctic, provides a unique opportunity to further our understanding of the polar regions of Earth and Mars.

  20. Subsurface Filamentous Fabrics: An Evaluation of Origins Based on Morphological and Geochemical Criteria, with Implications for Exopaleontology

    NASA Astrophysics Data System (ADS)

    Hofmann, Beda A.; Farmer, Jack D.; von Blanckenburg, Friedhelm; Fallick Anthony E.

    2008-02-01

    The fossil record of the subsurface biosphere is sparse. Results obtained on subsurface filamentous fabrics (SFF) from >225 paleosubsurface sites in volcanics, oxidized ores, and paleokarst of subrecent to Proterozoic age are presented. SFF are mineral encrustations on filamentous or fibrous substrates that formed in subsurface environments. SFF occur in association with low-temperature aqueous mineral assemblages and consist of tubular, micron-thick (median 1.6 micron) filaments in high spatial density, which occur as irregular masses, matted fabrics, and vertically draped features that resemble stalactites. Micron-sized filamentous centers rule out a stalactitic origin. Morphometric analysis of SFF filamentous forms demonstrates that their shape more closely resembles microbial filaments than fibrous minerals. Abiogenic filament-like forms are considered unlikely precursors of most SFF, because abiogenic forms differ in the distribution of widths and have a lower degree of curvature and a lower number of direction changes. Elemental analyses of SFF show depletion in immobile elements (e.g., Al, Th) and a systematic enrichment in As and Sb, which demonstrates a relation to environments with high flows of water. Sulfur isotopic analyses are consistent with a biological origin of a SFF sample from a Mississippi Valley Type deposit, which is consistent with data in the literature. Fe isotopes in SFF and active analogue systems, however, allow no discrimination between biogenic and abiogenic origins. The origin of most SFF is explained as permineralized remains of microbial filaments that possibly record rapid growth during phases of high water flow that released chemical energy. It is possible that some SFF formed due to encrustation of mineral fibers. SFF share similarities with Microcodium from soil environments. SFF are a logical target in the search for past life on Mars. The macroscopic nature of many SFF allows for their relatively easy in situ recognition and

  1. Subsurface filamentous fabrics: an evaluation of origins based on morphological and geochemical criteria, with implications for exopaleontology.

    PubMed

    Hofmann, Beda A; Farmer, Jack D; von Blanckenburg, Friedhelm; Fallick, Anthony E

    2008-02-01

    The fossil record of the subsurface biosphere is sparse. Results obtained on subsurface filamentous fabrics (SFF) from >225 paleosubsurface sites in volcanics, oxidized ores, and paleokarst of subrecent to Proterozoic age are presented. SFF are mineral encrustations on filamentous or fibrous substrates that formed in subsurface environments. SFF occur in association with low-temperature aqueous mineral assemblages and consist of tubular, micron-thick (median 1.6 micron) filaments in high spatial density, which occur as irregular masses, matted fabrics, and vertically draped features that resemble stalactites. Micron-sized filamentous centers rule out a stalactitic origin. Morphometric analysis of SFF filamentous forms demonstrates that their shape more closely resembles microbial filaments than fibrous minerals. Abiogenic filament-like forms are considered unlikely precursors of most SFF, because abiogenic forms differ in the distribution of widths and have a lower degree of curvature and a lower number of direction changes. Elemental analyses of SFF show depletion in immobile elements (e.g., Al, Th) and a systematic enrichment in As and Sb, which demonstrates a relation to environments with high flows of water. Sulfur isotopic analyses are consistent with a biological origin of a SFF sample from a Mississippi Valley-Type deposit, which is consistent with data in the literature. Fe isotopes in SFF and active analogue systems, however, allow no discrimination between biogenic and abiogenic origins. The origin of most SFF is explained as permineralized remains of microbial filaments that possibly record rapid growth during phases of high water flow that released chemical energy. It is possible that some SFF formed due to encrustation of mineral fibers. SFF share similarities with Microcodium from soil environments. SFF are a logical target in the search for past life on Mars. The macroscopic nature of many SFF allows for their relatively easy in situ recognition and

  2. Expanding the borononucleotide family: synthesis of borono-analogues of dCMP, dGMP and dAMP.

    PubMed

    Martin, Anthony R; Mohanan, Kishor; Luvino, Delphine; Floquet, Nicolas; Baraguey, Carine; Smietana, Michael; Vasseur, Jean-Jacques

    2009-11-01

    We previously reported the synthesis of a borononucleotide analogue of thymidine monophosphate and its association towards the formation of a new borono-linked dinucleotide. Here we describe the completion of the set of four 2'-deoxyborononucleotide analogues of natural nucleotide monophosphates, namely the previously unknown dCbn, dGbn and dAbn. These analogues were all prepared from the respective 5'-aldehydic nucleosides through a homologation/reduction sequence. The borononucleotides were subsequently obtained by either borylation (dCbn and dGbn) or cross-metathesis (CM) in the presence of the Hoveyda-Grubbs catalyst (dAbn). The reversible formation of the corresponding dinucleotides between these new analogues and uridine was studied by (1)H NMR, and semi-empirical calculations were carried out to provide bond length and electrostatic information that assess the structural similarities existing between these bioisosteres and their natural counterparts.

  3. A readily synthesized cyclic pyrrolysine analogue for site-specific protein "click" labeling.

    PubMed

    Hao, Ziyang; Song, Yanqun; Lin, Shixian; Yang, Maiyun; Liang, Yujie; Wang, Jing; Chen, Peng R

    2011-04-21

    A concise route was developed for the facile synthesis of a cyclic pyrrolysine analogue bearing an azide handle. Directed evolution enabled the encoding of this non-natural amino acid in both prokaryotic and eukaryotic cells, which offers a highly efficient approach for the site-specific protein labeling using click chemistry.

  4. Synthesis and antibacterial evaluation of anziaic acid and analogues as topoisomerase I inhibitors

    PubMed Central

    Lin, Hao; Annamalai, Thirunavukkarasu; Bansod, Priyanka; Tse-Dinh, Yuk-Ching

    2013-01-01

    Naturally occurring anziaic acid was very recently reported as a topoisomerase I inhibitor with antibacterial activity. Herein total synthesis of anziaic acid and structural analogues is described and the preliminary structure-activity relationship (SAR) has been developed based on topoisomerase inhibition and whole cell antibacterial activity. PMID:24363888

  5. Synthesis and anticancer evaluation of spermatinamine analogues.

    PubMed

    Moosa, Basem A; Sagar, Sunil; Li, Song; Esau, Luke; Kaur, Mandeep; Khashab, Niveen M

    2016-03-15

    Spermatinamine was isolated from an Australian marine sponge, Pseudoceratina sp. as an inhibitor of isoprenylcysteine carboxyl methyltransferase (Icmt), an attractive and novel anticancer target. Herein, we report the synthesis of spermatinamine analogues and their cytotoxic evaluation against three human cancer cell lines, that is, cervix adenocarcinoma (HeLa), breast adenocarcinoma (MCF-7), and prostate carcinoma (DU145). Analogues 12, 14 and 15 were found to be the most potent against one or more cell lines with the IC50 values in the range of 5-10 μM. The obtained results suggested that longer polyamine linker along with aromatic oxime substitution provided the most potent analogue compounds against cancer cell lines. PMID:26874403

  6. Pharmacologic profiles of investigational kisspeptin/metastin analogues, TAK-448 and TAK-683, in adult male rats in comparison to the GnRH analogue leuprolide.

    PubMed

    Matsui, Hisanori; Masaki, Tsuneo; Akinaga, Yumiko; Kiba, Atsushi; Takatsu, Yoshihiro; Nakata, Daisuke; Tanaka, Akira; Ban, Junko; Matsumoto, Shin-ichi; Kumano, Satoshi; Suzuki, Atsuko; Ikeda, Yukihiro; Yamaguchi, Masashi; Watanabe, Tatsuya; Ohtaki, Tetsuya; Kusaka, Masami

    2014-07-15

    Kisspeptin/metastin, a hypothalamic peptide, plays a pivotal role in controlling gonadotropin-releasing hormone (GnRH) neurons, and we have shown that continuous subcutaneous administration of kisspeptin analogues suppresses plasma testosterone in male rats. This study examined pharmacologic profiles of investigational kisspeptin analogues, TAK-448 and TAK-683, in male rats. Both analogues showed high receptor-binding affinity and potent and full agonistic activity for rat KISS1R, which were comparable to natural peptide Kp-10. A daily subcutaneous injection of TAK-448 and TAK-683 (0.008-8μmol/kg) for consecutive 7 days initially induced an increase in plasma luteinizing hormone and testosterone levels; however, after day 7, plasma hormone levels and genital organ weights were reduced. Continuous subcutaneous administrations of TAK-448 (≥10pmol/h, ca. 0.7nmol/kg/day) and TAK-683 (≥30pmol/h, ca. 2.1nmol/kg/day) induced a transient increase in plasma testosterone, followed by abrupt reduction of plasma testosterone to castrate levels within 3-7 days. This profound testosterone-lowering effect was sustained throughout 4-week dosing periods. At those dose levels, the weights of the prostate and seminal vesicles were reduced to castrate levels. These suppressive effects of kisspeptin analogues were more rapid and profound than those induced by the GnRH agonist analogue leuprolide treatment. In addition, TAK-683 reduced plasma prostate specific antigen (PSA) in the JDCaP androgen-dependent prostate cancer rat model. Thus, chronic administration of kisspeptin analogues may hold promise as a novel therapeutic approach for suppressing reproductive functions and hormone-related diseases such as prostate cancer. Further studies are warranted to elucidate clinical significance of TAK-448 and TAK-683.

  7. Geochemical and spectral characterization of naturally altered rock surfaces

    NASA Technical Reports Server (NTRS)

    Chang, L. L. Y.; Sommer, S. E.; Buckingham, W. F.

    1981-01-01

    The possibility of using the visible-near infrared region for compositional analysis of remotely sensed rock surfaces is studied. This would allow mapping rock type both on the Earth's surface and on other planetary surfaces. Reflectance spectroscopy, economic geology, optical depth determination, and X-ray diffraction mineralogy are discussed.

  8. Antarctica natural laboratory and space analogue for psychological research.

    PubMed

    Suedfeld, P; Weiss, K

    2000-01-01

    This introduction to the special issue traces the history of psychosocial concerns related to Antarctic exploration, from the heroic age of early explorers through the International Geophysical Year (IGY) of 1957 to 1958 to recent and current systematic research projects. The introduction discusses the organization and topics of international psychological investigations in polar stations and summarizes the articles that follow. Living in Antarctica imposes some unusual restrictions as well as opportunities, and it requires psychological adaptation to extreme environmental circumstances. The thrust of previous scientific and popular literature has been to focus on the negative effects of the situation and ignore the positive ones; however, ongoing studies are bringing about a more balanced view. Having an accurate understanding is important not only intrinsically and for appropriate application in the Antarctic itself but also in analogous extreme and unusual environments. These include extended space flight and space habitation, such as the projected voyage to Mars.

  9. Antarctica natural laboratory and space analogue for psychological research.

    PubMed

    Suedfeld, P; Weiss, K

    2000-01-01

    This introduction to the special issue traces the history of psychosocial concerns related to Antarctic exploration, from the heroic age of early explorers through the International Geophysical Year (IGY) of 1957 to 1958 to recent and current systematic research projects. The introduction discusses the organization and topics of international psychological investigations in polar stations and summarizes the articles that follow. Living in Antarctica imposes some unusual restrictions as well as opportunities, and it requires psychological adaptation to extreme environmental circumstances. The thrust of previous scientific and popular literature has been to focus on the negative effects of the situation and ignore the positive ones; however, ongoing studies are bringing about a more balanced view. Having an accurate understanding is important not only intrinsically and for appropriate application in the Antarctic itself but also in analogous extreme and unusual environments. These include extended space flight and space habitation, such as the projected voyage to Mars. PMID:11542946

  10. Radionuclide releases from natural analogues of spent nuclear fuel

    SciTech Connect

    Curtis, D.B.; Fabryka-Martin, J.; Dixon, P.; Aguilar, R.; Rokop, D.; Cramer, J.

    1993-12-31

    Measures of {sup 99}Tc, {sup 129}I, {sup 239}Pu and U concentrations in rock samples from uranium deposits at Cigar Lake and Koongarra have been used to study processes of radionuclide release from uranium minerals. Rates of release have been immeasurably slow at Cigar Lake. At Koongarra release rates appear to have been faster, producing small deficiencies of {sup 99}Tc, and larger ones of {sup 129}I. The inferred differences in radionuclide release rates are consistent with expected differences in uranium mineral degradation rates produced by the differing hydrogeochemical environments at the two sites.

  11. Characterization of Synthetic and Natural Manganese Oxides as Martian Analogues

    NASA Technical Reports Server (NTRS)

    Fox, V. K.; Arvidson, R. E.; Jolliff, B. L.; Carpenter, P. K.; Catalano, J. G.; Hinkle, M. A. G.; Morris, R. V.

    2015-01-01

    Recent discoveries of highly concentrated manganese oxides in Gale Crater and on the rim of Endeavour Crater by the Mars Science Laboratory Curiosity and Mars Exploration Rover Opportunity, respectively, imply more highly oxidizing aqueous conditions than previously recognized. Manganese oxides are a significant environmental indicator about ancient aqueous conditions, provided the phases can be characterized reliably. Manganese oxides are typically fine-grained and poorly crystalline, making the mineral structures difficult to determine, and they generally have very low visible reflectance with few distinctive spectral features in the visible to near infrared, making them a challenge for interpretation from remote sensing data. Therefore, these recent discoveries motivate better characterization using methods available on Mars, particularly visible to near infrared (VNIR) spectroscopy, X-ray diffractometry (XRD), and compositional measurements. Both rovers have complementary instruments in this regard. Opportunity is equipped with its multispectral visible imager, Pancam, and an Alpha Particle X-ray Spectrometer (APXS), and Curiosity has the multispectral Mastcam, ChemCam (laser-induced breakdown spectroscopy and passive spectroscopy), and APXS for in situ characterization, and ChemMin (XRD) for collected samples.

  12. Community-Based Development of Standards for Geochemical and Geochronological Data

    NASA Astrophysics Data System (ADS)

    Lehnert, K. A.; Walker, D.; Vinay, S.; Djapic, B.; Ash, J.; Falk, B.

    2007-12-01

    The Geoinformatics for Geochemistry (GfG) Program (www.geoinfogeochem.org) and the EarthChem project (www.earthchem.org) aim to maximize the application of geochemical data in Geoscience research and education by building a new advanced data infrastructure for geochemistry that facilitates the compilation, communication, serving, and visualization of geochemical data and their integration with the broad Geoscience data set. Building this new data infrastructure poses substantial challenges that are primarily cultural in nature, and require broad community involvement in the development and implementation of standards for data reporting (e.g., metadata for analytical procedures, data quality, and analyzed samples), data publication, and data citation to achieve broad acceptance and use. Working closely with the science community, with professional societies, and with editors and publishers, recommendations for standards for the reporting of geochemical and geochronological data in publications and to data repositories have been established, which are now under consideration for adoption in journal and agency policies. The recommended standards are aligned with the GfG and EarthChem data models as well as the EarthChem XML schema for geochemical data. Through partnerships with other national and international data management efforts in geochemistry and in the broader marine and terrestrial geosciences, GfG and EarthChem seek to integrate their development of geochemical metadata standards, data format, and semantics with relevant existing and emerging standards and ensure compatibility and compliance.

  13. Geochemical interaction between subducting slab and mantle wedge:Insight from observation and numerical modelling

    NASA Astrophysics Data System (ADS)

    Baitsch Ghirardello, B.; Gerya, T. V.; Burg, J.-P.; Jagoutz, O.

    2009-04-01

    Understanding the subduction factory and geochemical interactions between subducting slab and the overlying non homogeneously depleted mantle wedge requires better knowledge of passways of slab-derived fluids and melts and their interactions with the melt source in the mantle wedge. Our approach of understanding subduction-related processes consists in coupled geochemical-petrological-thermomechanical numerical geodynamic modelling of subduction zones. With this method we can simulate and visualize the evolution of various fields such as temperature, pressure, melt production etc. Furthermore we extend this tool for 2D and 3D modelling of the evolution of various geochemical signatures in subduction zones. Implementation of geochemical signatures in numerical models is based on marker-in-cell method and allows capturing influences of various key processes such as mechanical mixing of crustal and mantle rocks, fluid release, transport and consuming and melt generation and extraction. Concerning the isotopic signatures, we focus at the first stage on a limited number of elements: Pb, Hf, Sr and Nd. These incompatible elements are transported by hydrated fluids and/or melts through the mantle wedge and therefore they are good tracers for presenting the interaction between mantle wedge and slab. The chosen incompatible elements are also well explored and a large data set is available from literature. At this stage we focus on intra-oceanic subduction and numerical modelling predictions are compared to natural geochemical data from various modern and fossil subduction zones (Aleutian, Marianas, New Britain, Kermadec arcs, Kohistan, Vanuatu).

  14. Classical Simulated Annealing Using Quantum Analogues

    NASA Astrophysics Data System (ADS)

    La Cour, Brian R.; Troupe, James E.; Mark, Hans M.

    2016-08-01

    In this paper we consider the use of certain classical analogues to quantum tunneling behavior to improve the performance of simulated annealing on a discrete spin system of the general Ising form. Specifically, we consider the use of multiple simultaneous spin flips at each annealing step as an analogue to quantum spin coherence as well as modifications of the Boltzmann acceptance probability to mimic quantum tunneling. We find that the use of multiple spin flips can indeed be advantageous under certain annealing schedules, but only for long anneal times.

  15. A new class of conjugated strigolactone analogues with fluorescent properties: synthesis and biological activity.

    PubMed

    Bhattacharya, Chaitali; Bonfante, Paola; Deagostino, Annamaria; Kapulnik, Yoram; Larini, Paolo; Occhiato, Ernesto G; Prandi, Cristina; Venturello, Paolo

    2009-09-01

    A new class of strigolactone analogues has been synthesized. They differ from known molecules, both of natural and synthetic origin, in two main features. The conjugated system extends from the enol ether bridge to the A ring, the B ring is a heterocycle while the C ring is a cyclic ketone instead of a gamma-lactone. The key step of the synthesis is a Nazarov cyclization on activated substrates. Bioassays using Orobanche seeds have revealed that all the molecules strongly stimulate germination; in particular the oxygen containing analogues are the most active. Interestingly, some of the new molecules show fluorescent properties. PMID:19675895

  16. Inhibition of cobalamin-dependent enzymes by cobalamin analogues in rats.

    PubMed Central

    Stabler, S P; Brass, E P; Marcell, P D; Allen, R H

    1991-01-01

    To determine which parts of the cobalamin (cbl) molecule are required for enzyme activity and which parts, if altered, might inhibit cbl-dependent enzyme activity, we synthesized 16 cbl analogues and administered them to nutritionally normal rats. The cbl analogues, with either modifications of the propionamide side chains of the A-, B-, and C-rings, the acetamide side chain of the B-ring, or the nucleotide moiety, were administered to rats by continuous 14-d subcutaneous infusion. Infusion of cbl-stimulated, cbl-dependent activity. Changes in any part of the cbl molecule always abolished stimulation and, in some cases, caused potent inhibition of both cbl-dependent enzymes. The most inhibitory analogues, OH-cbl[c-lactam], a B-ring analogue, and OH-cbl[e-dimethylamide] and OH-cbl[e-methylamide], two C-ring analogues, decreased mean liver holo-L-methylmalonyl-coenzyme A mutase activity to 65% of control values and increased serum methylmalonic acid concentrations to as high as 3,200% of the control values. Liver methionine synthetase activity was decreased to approximately 20% of the control and mean serum total homocysteine concentrations were increased to 340% of control. A similar level of inhibition was demonstrated in rats who were exposed to 28 d of inhaled nitrous oxide or a prolonged period of dietary cbl deficiency. The inhibitory cbl analogues, nitrous oxide, and diet deficiency all depleted liver cbl. The naturally occurring cbl analogues with modifications of the nucleotide moiety had no effects. We conclude that all parts of the cbl molecule are necessary for in vivo cbl-dependent enzyme activity and that modifications of the side chains of the B and C rings are associated with potent in vivo inhibition of cbl-dependent enzyme activity. PMID:1672697

  17. Eco-Friendly Insecticide Discovery via Peptidomimetics: Design, Synthesis, and Aphicidal Activity of Novel Insect Kinin Analogues.

    PubMed

    Zhang, Chuanliang; Qu, Yanyan; Wu, Xiaoqing; Song, Dunlun; Ling, Yun; Yang, Xinling

    2015-05-13

    Insect kinin neuropeptides are pleiotropic peptides that are involved in the regulation of hindgut contraction, diuresis, and digestive enzyme release. They share a common C-terminal pentapeptide sequence of Phe(1)-Xaa(2)-Yaa(3)-Trp(4)-Gly(5)-NH2 (where Xaa(2) = His, Asn, Phe, Ser, or Tyr; Yaa(3) = Pro, Ser, or Ala). Recently, the aphicidal activity of insect kinin analogues has attracted the attention of researchers. Our previous work demonstrated that the sequence-simplified insect kinin pentapeptide analogue Phe-Phe-[Aib]-Trp-Gly-NH2 could retain good aphicidal activity and be the lead compound for the further discovery of eco-friendly insecticides which encompassed a broad array of biochemicals derived from micro-organisms and other natural sources. Using the peptidomimetics strategy, we chose Phe-Phe-[Aib]-Trp-Gly-NH2 as the lead compound, and we designed and synthesized three series, including 31 novel insect kinin analogues. The aphicidal activity of the new analogues against soybean aphid was determined. The results showed that all of the analogues exhibited aphicidal activity. Of particular interest was the analogue II-1, which exhibited improved aphicidal activity with an LC50 of 0.019 mmol/L compared with the lead compound (LC50 = 0.045 mmol/L) or the commercial insecticide pymetrozine (LC50 = 0.034 mmol/L). This suggests that the analogue II-1 could be used as a new lead for the discovery of potential eco-friendly insecticides.

  18. Conformationally restricted (+)-cacospongionolide B analogues. Influence on secretory phospholipase A2 inhibition.

    PubMed

    Murelli, Ryan P; Cheung, Atwood K; Snapper, Marc L

    2007-03-01

    A new approach to (+)-cacospongionolide was developed to access conformationally restricted variants of the natural product. The flexible aliphatic region between the decalin and side chain portion of the natural product was replaced with alkenyl and alkynyl linkers to probe the influence of structural rigidity in the inhibition of secretary phospholipase A2 (sPLA2). It was found that when the aliphatic section is replaced with a Z-olefin or an alkyne, sPLA2 inhibitory activity suffered relative to the natural product; however, an E-olefin-containing analogue led to an enhanced activity. These results suggest that preferred sPLA2 binding conformation of the natural product is similar to the geometry of the E-olefin-containing analogue.

  19. Laboratory simulation of organic geochemical processes.

    NASA Technical Reports Server (NTRS)

    Eglinton, G.

    1972-01-01

    Discussion of laboratory simulations that are important to organic geochemistry in that they provide direct evidence relating to geochemical cycles involving carbon. Reviewed processes and experiments include reactions occurring in the geosphere, particularly, short-term diagenesis of biolipids and organochlorine pesticides in estuarine muds, as well as maturation of organic matter in ancient sediments.

  20. Geochemical Reaction Mechanism Discovery from Molecular Simulation

    SciTech Connect

    Stack, Andrew G.; Kent, Paul R. C.

    2014-11-10

    Methods to explore reactions using computer simulation are becoming increasingly quantitative, versatile, and robust. In this review, a rationale for how molecular simulation can help build better geochemical kinetics models is first given. We summarize some common methods that geochemists use to simulate reaction mechanisms, specifically classical molecular dynamics and quantum chemical methods and discuss their strengths and weaknesses. Useful tools such as umbrella sampling and metadynamics that enable one to explore reactions are discussed. Several case studies wherein geochemists have used these tools to understand reaction mechanisms are presented, including water exchange and sorption on aqueous species and mineral surfaces, surface charging, crystal growth and dissolution, and electron transfer. The impact that molecular simulation has had on our understanding of geochemical reactivity are highlighted in each case. In the future, it is anticipated that molecular simulation of geochemical reaction mechanisms will become more commonplace as a tool to validate and interpret experimental data, and provide a check on the plausibility of geochemical kinetic models.

  1. Geochemical Reaction Mechanism Discovery from Molecular Simulation

    DOE PAGESBeta

    Stack, Andrew G.; Kent, Paul R. C.

    2014-11-10

    Methods to explore reactions using computer simulation are becoming increasingly quantitative, versatile, and robust. In this review, a rationale for how molecular simulation can help build better geochemical kinetics models is first given. We summarize some common methods that geochemists use to simulate reaction mechanisms, specifically classical molecular dynamics and quantum chemical methods and discuss their strengths and weaknesses. Useful tools such as umbrella sampling and metadynamics that enable one to explore reactions are discussed. Several case studies wherein geochemists have used these tools to understand reaction mechanisms are presented, including water exchange and sorption on aqueous species and mineralmore » surfaces, surface charging, crystal growth and dissolution, and electron transfer. The impact that molecular simulation has had on our understanding of geochemical reactivity are highlighted in each case. In the future, it is anticipated that molecular simulation of geochemical reaction mechanisms will become more commonplace as a tool to validate and interpret experimental data, and provide a check on the plausibility of geochemical kinetic models.« less

  2. Analogues of thiolactomycin as potential anti-malarial and anti-trypanosomal agents.

    PubMed

    Jones, Simon M; Urch, Jonathan E; Brun, Reto; Harwood, John L; Berry, Colin; Gilbert, Ian H

    2004-02-15

    A series of analogues of the naturally occurring antibiotic thiolactomycin (TLM) have been synthesised and evaluated for their ability to inhibit the growth of the malaria parasite, Plasmodium falciparum. Thiolactomycin is an inhibitor of Type II fatty acid synthase which is found in plants and most prokaryotes, but not an inhibitor of Type I fatty acid synthase in mammals. A number of the analogues showed inhibition equal to or greater than TLM. The introduction of hydrophobic alkyl groups at the C3 and C5 positions of the thiolactone ring lead to increased inhibition, the best showing a fourteenfold increase in activity over TLM. In addition, some of the analogues showed activity when assayed against the parasitic protozoa, Trypanosoma cruzi and Trypanosoma brucei.

  3. Synthesis and Structure activity relationships of EGCG Analogues, A Recently Identified Hsp90 Inhibitor

    PubMed Central

    Khandelwal, Anuj; Hall, Jessica

    2014-01-01

    Epigallocatechin-3-gallate (EGCG), the principal polyphenol isolated from green tea, was recently shown to inhibit Hsp90, however structure-activity relationships for this natural product have not yet been produced. Herein, we report the synthesis and biological evaluation of EGCG analogues to establish structure-activity relationships between EGCG and Hsp90. All four rings as well as the linker connecting the C- and the D-rings were systematically investigated, which led to the discovery of compounds that inhibit Hs90 and display improvement in efficacy over EGCG. Anti-proliferative activity of all the analogues was determined against MCF-7 and SKBr3 cell lines and Hsp90 inhibitory activity of four most potent analogues was further evaluated by western blot analyses and degradation of Hsp90-dependent client proteins. Prenyl substituted aryl ester of 3,5-dihydroxychroman-3-ol ring system was identified as novel scaffold that exhibit Hsp90 inhibitory activity. PMID:23834230

  4. Design, Synthesis and Cytotoxic Evaluation of o-Carboxamido Stilbene Analogues

    PubMed Central

    Azmi, Mohamad Nurul; Md Din, Mohd Fadzli; Kee, Chin Hui; Suhaimi, Munirah; Ping, Ang Kheng; Ahmad, Kartini; Nafiah, Mohd Azlan; Thomas, Noel F.; Mohamad, Khalit; Hoong, Leong Kok; Awang, Khalijah

    2013-01-01

    Resveratrol, a natural stilbene found in grapes and wines exhibits a wide range of pharmacological properties. Resveratrol is also known as a good chemopreventive agent for inhibiting carcinogenesis processes that target kinases, cyclooxygenases, ribonucleotide reductase and DNA polymerases. A total of 19 analogues with an amide moiety were synthesized and the cytotoxic effects of the analogues on a series of human cancer cell lines are reported. Three compounds 6d, 6i and 6n showed potent cytotoxicity against prostate cancer DU-145 (IC50 = 16.68 μM), colon cancer HT-29 (IC50 = 7.51 μM) and breast cancer MCF-7 (IC50 = 21.24 μM), respectively, which are comparable with vinblastine. The resveratrol analogues were synthesized using the Heck method. PMID:24287912

  5. Synthesis and evaluation of bioorthogonal pantetheine analogues for in vivo protein modification.

    PubMed

    Meier, Jordan L; Mercer, Andrew C; Rivera, Heriberto; Burkart, Michael D

    2006-09-20

    In vivo carrier protein tagging has recently become an attractive target for the site-specific modification of fusion systems and new approaches to natural product proteomics. A detailed study of pantetheine analogues was performed in order to identify suitable partners for covalent protein labeling inside living cells. A rapid synthesis of pantothenamide analogues was developed and used to produce a panel which was evaluated for in vitro and in vivo protein labeling. Kinetic comparisons allowed the construction of a structure-activity relationship to pinpoint the linker, dye, and bioorthogonal reporter of choice for carrier protein labeling. Finally bioorthogonal pantetheine analogues were shown to target carrier proteins with high specificity in vivo and undergo chemoselective ligation to reporters in crude cell lysate. The methods demonstrated here allow carrier proteins to be visualized and isolated for the first time without the need for antibody techniques and set the stage for the future use of carrier protein fusions in chemical biology.

  6. Synthesis and Pharmacological Evaluation of DHβE Analogues as Neuronal Nicotinic Acetylcholine Receptor Antagonists

    PubMed Central

    2014-01-01

    Dihydro-β-erythroidine (DHβE) is a member of the Erythrina family of alkaloids and a potent competitive antagonist of the α4β2-subtype of the nicotinic acetylcholine receptors (nAChRs). Guided by an X-ray structure of DHβE in complex with an ACh binding protein, we detail the design, synthesis, and pharmacological characterization of a series of DHβE analogues in which two of the four rings in the natural product has been excluded. We found that the direct analogue of DHβE maintains affinity for the α4β2-subtype, but further modifications of the simplified analogues were detrimental to their activities on the nAChRs. PMID:25050162

  7. Synthesis and structure-activity relationships of EGCG analogues, a recently identified Hsp90 inhibitor.

    PubMed

    Khandelwal, Anuj; Hall, Jessica A; Blagg, Brian S J

    2013-08-16

    Epigallocatechin-3-gallate (EGCG), the principal polyphenol isolated from green tea, was recently shown to inhibit Hsp90; however, structure-activity relationships for this natural product have not yet been produced. Herein, we report the synthesis and biological evaluation of EGCG analogues to establish structure-activity relationships between EGCG and Hsp90. All four rings as well as the linker connecting the C- and the D-rings were systematically investigated, which led to the discovery of compounds that inhibit Hs90 and display improvement in efficacy over EGCG. Antiproliferative activity of all the analogues was determined against MCF-7 and SKBr3 cell lines and Hsp90 inhibitory activity of the four most potent analogues was further evaluated by Western blot analyses and degradation of Hsp90-dependent client proteins. The prenyl-substituted aryl ester of 3,5-dihydroxychroman-3-ol ring system was identified as a novel scaffold that exhibits Hsp90 inhibitory activity. PMID:23834230

  8. Syntheses and Biological Evaluation of Costunolide, Parthenolide, and Their Fluorinated Analogues.

    PubMed

    Yang, Zhong-Jin; Ge, Wei-Zhi; Li, Qiu-Ying; Lu, Yaxin; Gong, Jian-Miao; Kuang, Bei-Jia; Xi, Xiaonan; Wu, Haiting; Zhang, Quan; Chen, Yue

    2015-09-10

    Inspired by the biosynthesis of sesquiterpene lactones (SLs), herein we report the asymmetric total synthesis of the germacrane ring (24). The synthetic strategy features a selective aldol reaction between β,γ-unsaturated chiral sulfonylamide 15a and aldehyde 13, as well as the intramolecular α-alkylation of sulfone 21 to construct a 10-membered carbocylic ring. The key intermediate 24 can be used to prepare the natural products costunolide and parthenolide (PTL), which are the key precursors for transformation into other SLs. Furthermore, the described synthetic sequences are amenable to the total synthesis of SL analogues, such as trifluoromethylated analogues 32 and 45. Analogues 32 and 45 maintained high activities against a series of cancer cell lines compared to their parent PTL and costunolide, respectively. In addition, 32 showed enhanced tolerance to acidic media compared with PTL. To our surprise, PTL and 32 showed comparable half-lives in rat plasma and in the presence of human liver microsomes. PMID:26226279

  9. Synthesis, DNA Binding and Antitumor Evaluation of Styelsamine and Cystodytin Analogues

    PubMed Central

    Fong, Hugo K. H.; Copp, Brent R.

    2013-01-01

    A series of N-14 sidechain substituted analogues of styelsamine (pyrido[4,3,2-mn]acridine) and cystodytin (pyrido[4,3,2-mn]acridin-4-one) alkaloids have been prepared and evaluated for their DNA binding affinity and antiproliferative activity towards a panel of human tumor cell lines. Overall it was found that styelsamine analogues were stronger DNA binders, with the natural products styelsamines B and D having particularly high affinity (Kapp 5.33 × 106 and 3.64 × 106 M−1, respectively). In comparison, the cystodytin iminoquinone alkaloids showed lower affinity for DNA, but were typically just as active as styelsamine analogues at inhibiting proliferation of tumor cells in vitro. Sub-panel selectivity towards non-small cell lung, melanoma and renal cancer cell lines were observed for a number of the analogues. Correlation was observed between whole cell activity and clogP, with the most potent antiproliferative activity being observed for 3-phenylpropanamide analogues 37 and 41 (NCI panel average GI50 0.4 μM and 0.32 μM, respectively) with clogP ~4.0–4.5. PMID:23358307

  10. Theoretical study on absorption and emission spectra of pyrrolo-C analogues

    NASA Astrophysics Data System (ADS)

    Liu, Hongxia; Liu, Jianhua; Yang, Yan; Li, Yan; Wang, Haijun

    2015-01-01

    Fluorescent nucleoside analogues have attracted much attention in studying the structure and dynamics of nucleic acids in recent years. In the present work, we use theoretical calculations to investigate the structural and optical properties of Pyrrolo-C (PyC) and its analogues which are modified via the conjugation or fusion of different aromatic ring to the PyC core. We also consider the effects of aqueous solution and base pairing. The results show that the fluorescent pyrrolo-C analogues can pair with guanosine to form stable H-bonded WC base pairs. The calculated absorption peaks of modified deoxyribonucleosides agree well with the measured data. The absorption and emission maxima of the pyrrolo-C analogues are greatly red shifted compared with nature C. The solvent effects can induce wavelength blue shift and increase the oscillator strengths in both the absorption and emission spectra. With regard to the WC base pairs, the B3LYP functional reveals that the lowest energy transitions of modified GC base pairs are charge transfer excitation while the CAM-B3LYP functional predicts that all the lowest transitions are localised on the pyrrolo-C analogues. The M062X and CAM-B3LYP functionals show good agreement with respect to both the value of the lowest energy transitions as well as the oscillator strengths.

  11. Synthesis and Evaluation of Novel Triterpene Analogues of Ursolic Acid as Potential Antidiabetic Agent.

    PubMed

    Wu, Panpan; Zheng, Jie; Huang, Tianming; Li, Dianmeng; Hu, Qingqing; Cheng, Anming; Jiang, Zhengyun; Jiao, Luoying; Zhao, Suqing; Zhang, Kun

    2015-01-01

    Ursolic acid (UA) is a naturally bioactive compound that possesses potential anti-diabetic activity. The relatively safe and effective molecule intrigued us to further explore and to improve its anti-diabetic activity. In the present study, a series of novel UA analogues was synthesized and their structures were characterized. Their bioactivities against the α-glucosidase from baker's yeast were determined in vitro. The results suggested that most of the analogues exhibited significant inhibitory activity, especially analogues 8b and 9b with the IC50 values of 1.27 ± 0.27 μM (8b) and 1.28 ± 0.27 μM (9b), which were lower than the other analogues and the positive control. The molecular docking and 2D-QSAR studies were carried out to prove that the C-3 hydroxyl could interact with the hydrophobic region of the active pocket and form hydrogen bonds to increase the binding affinity of ligand and the homology modelling protein. Thus, these results will be helpful for understanding the relationship between binding mode and bioactivity and for designing better inhibitors from UA analogues. PMID:26406581

  12. Synthesis and Structure–Activity Relationship Study of 5a-Carbasugar Analogues of SL0101

    PubMed Central

    2014-01-01

    The Ser/Thr protein kinase, RSK, is associated with oncogenesis, and therefore, there are ongoing efforts to develop RSK inhibitors that are suitable for use in vivo. SL0101 is a natural product that demonstrates selectivity for RSK inhibition. However, SL0101 has a short biological half-life in vivo. To address this issue we designed a set of eight cyclitol analogues, which should be resistant to acid catalyzed anomeric bond hydrolysis. The analogues were synthesized and evaluated for their ability to selectively inhibit RSK in vitro and in cell-based assays. All the analogues were prepared using a stereodivergent palladium-catalyzed glycosylation/cyclitolization for installing the aglycon. The l-cyclitol analogues were found to inhibit RSK2 in in vitro kinase activity with a similar efficacy to that of SL0101, however, the analogues were not specific for RSK in cell-based assays. In contrast, the d-isomers showed no RSK inhibitory activity in in vitro kinase assay. PMID:25589938

  13. Synthesis and Evaluation of Novel Triterpene Analogues of Ursolic Acid as Potential Antidiabetic Agent

    PubMed Central

    Wu, Panpan; Zheng, Jie; Huang, Tianming; Li, Dianmeng; Hu, Qingqing; Cheng, Anming; Jiang, Zhengyun; Jiao, Luoying; Zhao, Suqing; Zhang, Kun

    2015-01-01

    Ursolic acid (UA) is a naturally bioactive compound that possesses potential anti-diabetic activity. The relatively safe and effective molecule intrigued us to further explore and to improve its anti-diabetic activity. In the present study, a series of novel UA analogues was synthesized and their structures were characterized. Their bioactivities against the α-glucosidase from baker's yeast were determined in vitro. The results suggested that most of the analogues exhibited significant inhibitory activity, especially analogues 8b and 9b with the IC50 values of 1.27 ± 0.27 μM (8b) and 1.28 ± 0.27 μM (9b), which were lower than the other analogues and the positive control. The molecular docking and 2D-QSAR studies were carried out to prove that the C-3 hydroxyl could interact with the hydrophobic region of the active pocket and form hydrogen bonds to increase the binding affinity of ligand and the homology modelling protein. Thus, these results will be helpful for understanding the relationship between binding mode and bioactivity and for designing better inhibitors from UA analogues. PMID:26406581

  14. Geochemical Mapping of 4 Vesta Begins

    NASA Technical Reports Server (NTRS)

    Prettyman, Thomas H.; Feldman, William C.; Forni, Olivier; Joy, Steven P.; Lawrence, David J.; LeCorre, Lucille; Mafi, Joseph N.; McCord, Thomas B.; McCoy, Timothy J.; McSween, Harry Y.; Middlefehldt, David W.; Polanskey, Carol; Rayman, Marc; Raymond, Carol A.; Reddy, Vishnu; Reedy, Robert C.; Russell, Christopher T.; Titus, Timothy N.; Toplis, Mike J.

    2011-01-01

    By December, the NASA Dawn spacecraft will have descended to a low altitude mapping orbit (LAMO), where the Gamma Ray and Neutron Detector (GRaND) will acquire global mapping data for up to four months. Measurements by GRaND will help answer elusive questions about how Vesta differentiated and the nature of processes that shaped Vesta s surface. The data will be analyzed to determine the abundances of Mg, Si, Fe, K, Th, and H at a spatial resolution of roughly 300 km full-width-at-half-maximum from a 465 km radius orbit. Thermal and fast neutron counting data will be analyzed to determine the neutron macroscopic absorption cross section and average atomic mass, providing constraints on additional elements, such as Ca and Al. GRaND will quantify the elemental composition of coarse spatial units identified by Dawn s Framing Camera (FC) and the Visible & Infrared Spectrometer (VIR). In addition, GRaND will map the mixing ratio of compositional end members selected from the howardite, eucrite and diogenite (HED) meteorites, determine the relative proportions of plagioclase and mafic minerals, and search for compositions that are absent or under-represented in the meteorite collection. While it is generally thought that Vesta s crust on a regional scale should be well-represented by linear mixing of HED whole-rock compositions, there are hints that Vesta may be more diverse than implied by this model. For example, the discovery of K-rich impact glasses in howardites suggests that K-rich rocks may be present on a portion of Vesta s surface, and the analysis of diogenites indicates considerable variability in the magmatic processes that formed them. The chemical composition of materials within Vesta s south polar structure may provide further clues to how it formed. An impact might have exposed mantle and lower crustal materials, which should have a distinctive compositional signature. We present the analysis of data acquired by GRaND from cruise through the descent to

  15. Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

    USGS Publications Warehouse

    Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2011-01-01

    The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons

  16. Geobiochemistry: Placing Biochemistry in Its Geochemical Context

    NASA Astrophysics Data System (ADS)

    Shock, E.; Boyer, G. M.; Canovas, P. A., III; Prasad, A.; Dick, J. M.

    2014-12-01

    Goals of geobiochemistry include simultaneously evaluating the relative stabilities of microbial cells and minerals, and predicting how the composition of biomolecules can change in response to the progress of geochemical reactions. Recent developments in theoretical geochemistry make it possible to predict standard thermodynamic properties of proteins, nucleotides, lipids, and many metabolites including the constituents of the citric acid cycle, at all temperatures and pressures where life is known to occur, and beyond. Combining these predictions with constraints from geochemical data makes it possible to assess the relative stabilities of biomolecules. Resulting independent predictions of the environmental occurrence of homologous proteins and lipid side-chains can be compared with observations from metagenomic and metalipidomic data to quantify geochemical driving forces that shape the composition of biomolecules. In addition, the energetic costs of generating biomolecules from within a diverse range of habitable environments can be evaluated in terms of prevailing geochemical variables. Comparisons of geochemical bioenergetic calculations across habitats leads to the generalization that the availability of H2 determines the cost of autotrophic biosynthesis relative to the aquatic environment external to microbial cells, and that pH, temperature, pressure, and availability of C, N, P, and S are typically secondary. Increasingly reduced conditions, which are determined by reactions of water with mineral surfaces and mineral assemblages, allow many biosynthetic reactions to shift from costing energy to releasing energy. Protein and lipid synthesis, as well as the reverse citric acid cycle, become energy-releasing processes under these conditions. The resulting energy balances that determine habitability contrast dramatically with assumptions derived from oxic surface conditions, such as those where human biochemistry operates.

  17. Pyridopyrimidine analogues as novel adenosine kinase inhibitors.

    PubMed

    Zheng, G Z; Lee, C; Pratt, J K; Perner, R J; Jiang, M Q; Gomtsyan, A; Matulenko, M A; Mao, Y; Koenig, J R; Kim, K H; Muchmore, S; Yu, H; Kohlhaas, K; Alexander, K M; McGaraughty, S; Chu, K L; Wismer, C T; Mikusa, J; Jarvis, M F; Marsh, K; Kowaluk, E A; Bhagwat, S S; Stewart, A O

    2001-08-20

    A novel series of pyridopyrimidine analogues 9 was identified as potent adenosine kinase inhibitors based on the SAR and computational studies. Substitution of the C7 position of the pyridopyrimidino core with C2' substituted pyridino moiety increased the in vivo potency and enhanced oral bioavailability of these adenosine kinase inhibitors.

  18. Dumb holes: analogues for black holes.

    PubMed

    Unruh, W G

    2008-08-28

    The use of sonic analogues to black and white holes, called dumb or deaf holes, to understand the particle production by black holes is reviewed. The results suggest that the black hole particle production is a low-frequency and low-wavenumber process.

  19. Stilbenophane analogues of deoxycombretastatin A-4.

    PubMed

    Mateo, Carmen; Pérez-Melero, Concepción; Peláez, Rafael; Medarde, Manuel

    2005-08-01

    A new family of polyoxygenated stilbenophanes has been synthesized as conformationally restricted analogues of antimitotic combretastatins. By means of the McMurry olefination process, compounds derived from diethyleneglycol and 1,6-hexanediol were obtained, whereas Grubbs' catalyst failed in producing the ring-closing metathesis to this kind of macrocyclic products.

  20. CO2 Capture with Enzyme Synthetic Analogue

    SciTech Connect

    Cordatos, Harry

    2010-03-01

    Project overview provides background on carbonic anhydrase transport mechanism for CO2 in the human body and proposed approach for ARPA-E project to create a synthetic enzyme analogue and utilize it in a membrane for CO2 capture from flue gas.

  1. Synthesis and antimicrobial activity of squalamine analogue.

    PubMed

    Kim, H S; Choi, B S; Kwon, K C; Lee, S O; Kwak, H J; Lee, C H

    2000-08-01

    Synthesis and antimicrobial activity of squalamine analogue 2 are reported. The synthesis of 2 was accomplished from bisnoralcohol 3. The spermidine moiety was introduced via reductive amination of an appropriately functionalized 3beta-aminosterol with spermidinyl aldehyde 17 utilizing sodium triacetoxyborohydride as the reducing agent. Compound 2 shows weaker antimicrobial activity than squalamine. PMID:11003150

  2. Geochemical mapping of New Mexico, USA, using stream sediment data

    NASA Astrophysics Data System (ADS)

    Zumlot, Taisser; Goodell, Philip; Howari, Fares

    2009-10-01

    The spatial analysis of geochemical data has several environmental and geological applications. The present study investigated the regional distribution of Al, Ba, Ca, Ce, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Na, Ni, Pb, Sc, Th, Ti, U, V, and Zn elements in stream sediment samples from New Mexico State. These elements were studied in order to integrate them with geological and environmental characteristics of the area. Data are used from 27,798 samples that were originally collected during the national uranium resource evaluation (NURE) Hydrogeochemical and stream sediment reconnaissance (HSSR) program in the 1970s. The original data are available as U.S. Geological Survey Open-File Report 97-492. The study used a variety of data processing and filtering techniques that included univariate, bivariate, factor analyses and spatial analyses to transform the data into a useable format. Principal component analysis and GIS techniques are applied to classify the elements and to identify geochemical signatures, either natural or anthropogenic. The study found that the distribution of the investigated elements is mainly controlled by the bed rock chemistry. For example, along the Rio Grande rift and Jemez lineament a strong association between Co, Cr, Cu, Fe, Ni, Sc, Ti, V and Zn was observed and indicates that elements distribution in the area controlled by the mafic factor. The rare earth elements (REE) factor which is consists of Ce, La and U, also has strong, localized, clusters in the felsic centers in New Mexico.

  3. Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations.

    PubMed

    Sengupta, Aditi; Wang, Yadi; Meira Neto, Antonio A; Matos, Katarena A; Dontsova, Katerina; Root, Rob; Neilson, Julie W; Maier, Raina M; Chorover, Jon; Troch, Peter A

    2016-01-01

    Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale. PMID:27684738

  4. Geochemical patterns in soils of the karst region, Croatia

    USGS Publications Warehouse

    Prohic, E.; Hausberger, G.; Davis, J.C.

    1997-01-01

    Soil samples were collected at 420 locations in a 5-km grid pattern in the Istria and Gorski Kotar areas of Croatia, and on the Croatian islands of Cres, Rab and Krk, in order to relate geochemical variation in the soils to underlying differences in geology, bedrock lithology, soil type, environment and natural versus anthropogenic influences. Specific objectives included assessment of possible agricultural and industrial sources of contamination, especially from airborne effluent emitted by a local power plant. The study also tested the adequacy of a fixed-depth soil sampling procedure developed for meager karstic soils. Although 40 geochemical variables were analyzed, only 15 elements and 5 radionuclides are common to all the sample locations. These elements can be divided into three groups: (1) those of mostly anthropogenic origin -Pb, V, Cu and Cr; (2) those of mixed origin - radionuclides and Zn; and (3) those of mostly geogene origin -Ba, Sr, Ti, Al, Na, Ca, Mg, Fe, Mn, Ni and Co. Variation in Pb shows a strong correlation with the pattern of road traffic in Istria. The distributions of Ca, Na and Mg in the flysch basins of southern Istria and Slovenia are clearly distinguishable from the distributions of these elements in the surrounding carbonate terrains, a consequence of differences in bedrock permeability, type of drainage and pH. The spatial pattern of Cs from the Chernobyl nuclear power plant accident reflects almost exclusively the precipitation in Istria during the days immediately after the explosion. ?? 1997 Elsevier Science B.V.

  5. [Dmt(1)]DALDA analogues modified with tyrosine analogues at position 1.

    PubMed

    Cai, Yunxin; Lu, Dandan; Chen, Zhen; Ding, Yi; Chung, Nga N; Li, Tingyou; Schiller, Peter W

    2016-08-01

    Analogues of [Dmt(1)]DALDA (H-Dmt-d-Arg-Phe-Lys-NH2; Dmt=2',6'-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity were prepared by replacing Dmt with various 2',6'-dialkylated Tyr analogues, including 2',4',6'-trimethyltyrosine (Tmt), 2'-ethyl-6'-methyltyrosine (Emt), 2'-isopropyl-6'-methyltyrosine (Imt) and 2',6'-diethyltyrosine (Det). All compounds were selective μ opioid agonists and the Tmt(1)-, Emt(1) and Det(1)-analogues showed subnanomolar μ opioid receptor binding affinities. The Tmt(1)- and Emt(1)-analogues showed improved antioxidant activity compared to the Dmt(1)-parent peptide in the DPPH radical-scavenging capacity assay, and thus are of interest as drug candidates for neuropathic pain treatment.

  6. [Dmt(1)]DALDA analogues modified with tyrosine analogues at position 1.

    PubMed

    Cai, Yunxin; Lu, Dandan; Chen, Zhen; Ding, Yi; Chung, Nga N; Li, Tingyou; Schiller, Peter W

    2016-08-01

    Analogues of [Dmt(1)]DALDA (H-Dmt-d-Arg-Phe-Lys-NH2; Dmt=2',6'-dimethyltyrosine), a potent μ opioid agonist peptide with mitochondria-targeted antioxidant activity were prepared by replacing Dmt with various 2',6'-dialkylated Tyr analogues, including 2',4',6'-trimethyltyrosine (Tmt), 2'-ethyl-6'-methyltyrosine (Emt), 2'-isopropyl-6'-methyltyrosine (Imt) and 2',6'-diethyltyrosine (Det). All compounds were selective μ opioid agonists and the Tmt(1)-, Emt(1) and Det(1)-analogues showed subnanomolar μ opioid receptor binding affinities. The Tmt(1)- and Emt(1)-analogues showed improved antioxidant activity compared to the Dmt(1)-parent peptide in the DPPH radical-scavenging capacity assay, and thus are of interest as drug candidates for neuropathic pain treatment. PMID:27301366

  7. VNIR spectral modeling of Mars analogue rocks: first results

    NASA Astrophysics Data System (ADS)

    Pompilio, L.; Roush, T.; Pedrazzi, G.; Sgavetti, M.

    Knowledge regarding the surface composition of Mars and other bodies of the inner solar system is fundamental to understanding of their origin, evolution, and internal structures. Technological improvements of remote sensors and associated implications for planetary studies have encouraged increased laboratory and field spectroscopy research to model the spectral behavior of terrestrial analogues for planetary surfaces. This approach has proven useful during Martian surface and orbital missions, and petrologic studies of Martian SNC meteorites. Thermal emission data were used to suggest two lithologies occurring on Mars surface: basalt with abundant plagioclase and clinopyroxene and andesite, dominated by plagioclase and volcanic glass [1,2]. Weathered basalt has been suggested as an alternative to the andesite interpretation [3,4]. Orbital VNIR spectral imaging data also suggest the crust is dominantly basaltic, chiefly feldspar and pyroxene [5,6]. A few outcrops of ancient crust have higher concentrations of olivine and low-Ca pyroxene, and have been interpreted as cumulates [6]. Based upon these orbital observations future lander/rover missions can be expected to encounter particulate soils, rocks, and rock outcrops. Approaches to qualitative and quantitative analysis of remotely-acquired spectra have been successfully used to infer the presence and abundance of minerals and to discover compositionally associated spectral trends [7-9]. Both empirical [10] and mathematical [e.g. 11-13] methods have been applied, typically with full compositional knowledge, to chiefly particulate samples and as a result cannot be considered as objective techniques for predicting the compositional information, especially for understanding the spectral behavior of rocks. Extending the compositional modeling efforts to include more rocks and developing objective criteria in the modeling are the next required steps. This is the focus of the present investigation. We present results of

  8. High-resolution mass spectrometry analysis of tetrodotoxin (TTX) and its analogues in puffer fish and shellfish.

    PubMed

    Bane, Vaishali; Brosnan, Brid; Barnes, Paul; Lehane, Mary; Furey, Ambrose

    2016-09-01

    Tetrodotoxin (TTX) is an emerging toxin in the European marine environment. It has various known structural analogues. It acts as a sodium channel blocker; the ability of each analogue to bind to the sodium channel varies with the particular structure of each analogue. Thus, each analogue will vary in its toxic potential. TTX analogues co-occur in food samples at variable concentrations. An LC-MS method was developed for the identification and quantitation of several analogues of TTX using an LTQ-Orbitrap XL mass spectrometer. The LTQ-Orbitrap XL mass spectrometer facilitates high mass accuracy measurement up to 100,000 full width at half maximum (FWHM). Using high resolution at 100,000 FWHM allows for the identification of TTX and its analogues in various matrices, including puffer fish and molluscan shellfish samples (Δ ppm = 0.28-3.38). The confirmation of characteristic fragment ions of TTX and its analogues was achieved by determining their elemental formulae via high mass accuracy. A quantitative method was then developed and optimised using these characteristic fragment ions. The limit of quantitation (LOQ) of the method was 0.136 µg g(-1) (S/N = 10) and the limit of detection (LOD) was 0.041 µg g(-1) (S/N = 3) spiking TTX standard into TTX-free mackerel fish extracts. The method was applied to naturally contaminated puffer fish and molluscan shellfish samples to confirm the presence of TTX and its analogues. PMID:27662433

  9. Pattern formation in geochemical systems

    NASA Astrophysics Data System (ADS)

    Katsev, Sergei

    2002-08-01

    Compositional patterns are extremely common in natural minerals. While, in many cases, variations in the solid mineral composition reflect the external changes in the environment at the time of the mineral formation, the role of self-organization is increasingly acknowledged. For example, in reaction-transport systems, the patterns may form spontaneously from an unpatterned state at the time of crystal growth and then become preserved by being "frozen" in the solid mineral. In this work, the pattern formation by self-organization is investigated by means of model construction and computer simulations in several minerals from different geologic environments. The impact of environmental noise is investigated on a model of oscillatory zoning in plagioclase feldspar. It is shown that environmental noise can lead to pattern formation such as oscillatory zoning, even when no deterministic periodic solutions exist. Coherence resonance close to the Hopf bifurcation is observed. Oscillatory zoning in barite-celestite system is simulated to quantitatively describe the results of the previously reported nucleation and growth experiments. The zoning is thought to be formed by autocatalytic growth from an aqueous solution. In addition to the description of the reaction-diffusion system in terns of partial and ordinary differential equations, a cellular automata model is proposed for the first time for this oscillatory crystallization type of problems. A quantitative model of banding in Mississippi Valley-type sphalerite is presented. Banded ring-like patterns are shown to arise due to a self-propagating sequence of growth and dissolution (coarsening wave). A two-dimensional model is presented for the first time and the conditions for the pattern generation and preservation are discussed. A number of time series analysis techniques are applied to characterize the compositional patterns observed in natural minerals as well as in the colored rythmites found in the marine clay

  10. Estimation of in situ groundwater chemistry using geochemical modeling: A test case for saline type groundwater in argillaceous rock

    NASA Astrophysics Data System (ADS)

    Sasamoto, Hiroshi; Yui, Mikazu; Arthur, Randolph C.

    Saline type groundwaters data in the Mobara area (a marine based argillaceous rock) located in the well-known “South Kanto gas field” in Japan were investigated by JNC as part of a natural analogue study. Most groundwaters in the field were extracted from deep gas wells ( e. g., 400-2000 m below the surface), and the all data reported previously were sampled at the wellhead, where physico-chemical parameters ( e. g., temperature, pH, Eh etc.) were also measured. In such cases, particular attention should be paid to whether the measured and/or analyzed results are consistent with the chemical and physical conditions in the in situ geological formation because air contamination, the temperature and pressure changes during sampling can affect the groundwater chemistry. The present study shows a test case to estimate the in situ groundwater chemistry in argillaceous rock of the Mobara area using geochemical model calculations. Results from thermodynamic interpretation of groundwater chemistry using the measured pH and Eh of groundwater sampled at wellhead ( e. g., pH = 7.86, Eh = -50 mV) indicate that the groundwaters are supersaturated with respect to calcite ( e. g., the saturation index; SI is 1.14). Calcite is known to equilibrate relatively quickly with aqueous solutions at low temperatures and this mineral is present in the Otadai formation, however. Therefore the values greater than 0 for SI of calcite may be due to errors in the pH measurement. Also the measured Eh is relatively oxidizing value which may be inconsistent with the in situ geochemical conditions ( e. g., pyrite and siderite coexist, CH 4(g) dominates in the groundwaters). Thus such Eh value may be disturbed by contact of the samples with atmospheric oxygen and other effects like degassing. Errors in the pH measurement might be caused by degassing during sampling of groundwaters. As a test case to estimate the groundwater considering such degassing effect, we first assume that the in situ

  11. Characterization of CO2-induced (?) bleaching phenomena in German red bed sediments by combined geochemical and evolved gas analysis

    NASA Astrophysics Data System (ADS)

    Hilse, Ulrike; Goepel, Andreas; Pudlo, Dieter; Heide, Klaus; Gaupp, Reinhard

    2010-05-01

    We investigated varied coloured Buntsandstein and Rotliegend sandstones in Central Germany (Thuringian Vorderrhön, Altmark) by thermogravimetric/pyrolytic (DEGAS- directly coupled evolved gas analysis) and geochemical (ICP-MS/OES) means to evaluate geochemical/mineralogical characteristics of red bed rocks and their presumably altered, bleached modifications. Commonly bleaching of primary red bed sediments is regarded as a result of fluid-rock reactions by the participation of CO2. This study is performed in the framework of the special research program 'GEOTECHNOLOGIEN' (funded by the German Ministry of Education and Research - BMBF) and is part of two BMBF sponsored projects - 'COMICOR', an analogue study on potential effects of CO2-bearing fluids on Buntsandstein and Rotliegend deposits in Hesse and Thuringia and 'CLEAN', an enhanced gas recovery (EGR) pilot project in cooperation with GDF SUEZ E&P Deutschland GmbH. The intention of CLEAN is to evaluate the feasibility of EGR techniques and the suitability of depleted natural gas reservoirs for potential industrial CO2 sequestration projects. According to rock colour variations two slices of handspecimens (M49, A1) were split into 12 and 15 equally sized samples for analytical work. The medium grained Lower Buntsandstein sample M49 from Thuringia is of fluvial origin and partially bleached with transitions from red (unbleached) to light colours (bleached). Bulk rock geochemistry of red bed and bleached subsamples of M49 are almost similar, including rare earth element (REE) content. Only the content of iron and related metals is depleted in bleached samples compared to the red bed types. All PAAS normalized pattern of M49 show positive Eu and slightly negative Ce anomalies, most likely caused by the presence of apatite and illite in the rocks. The degassing behavior observed by DEGAS of M49 subsamples is mainly controlled by the breakdown of sheet silicates, hydroxides and hydrates, as well as of carbonates and

  12. Human cognitive performance in spaceflight and analogue environments.

    PubMed

    Strangman, Gary E; Sipes, Walter; Beven, Gary

    2014-10-01

    Maintaining intact cognitive performance is a high priority for space exploration. This review seeks to summarize the cumulative results of existing studies of cognitive performance in spaceflight and analogue environments. We focused on long-duration (>21 d) studies for which no review has previously been conducted. There were 11 published studies identified for long-duration spaceflight (N = 42 subjects) as well as 21 shorter spaceflight studies (N = 70 subjects). Overall, spaceflight cognitive studies ranged from 6-438 d in duration. Some 55 spaceflight analogue studies were also identified, ranging from 6 to 520 d. The diverse nature of experimental procedures and protocols precluded formal meta-analysis. In general, the available evidence fails to strongly support or refute the existence of specific cognitive deficits in low Earth orbit during long-duration spaceflight, which may be due in large part to small numbers of subjects. The studies consistently suggest that novel environments (spaceflight or other) induce variable alterations in cognitive performance across individuals, consistent with known astronaut experiences. This highlights the need to better quantify the magnitude and scope of this interindividual variability, and understand its underlying factors, when predicting in-flight cognitive functioning for extended periods. PMID:25245904

  13. Electromagnetic induction in New Zealand: analogue model and field results

    NASA Astrophysics Data System (ADS)

    Chen, J.; Dosso, H. W.; Ingham, M.

    The behaviour of electric and magnetic variations over North Island (New Zealand) is studied with the aid of a laboratory analogue model. The source field frequencies used in the analogue modelling simulate naturally occurring geomagnetic variations of 5-120 min periods. In-phase and quadrature magnetic and electric fields for a selection of traverses for the modelled region of North Island are presented. Since North Island is of a relatively narrow cross-section, the field responses, even for inland locations, are expected to show strongly the effects of the surrounding ocean. The irregular coastlines, as well as the strait between North and South Islands, lead to coastal and inland field anomalies due to induced currents being deflected and channelled to produce localized current densities. The comparison of model results with field station measurements obtained earlier individually by Ingham and by Midha for sites in the northeastern, central, and southern (near Cook Strait) regions of North Island demonstrates the large role the ocean has in the observed field responses. Differences in the model and field results at some sites are expected and should reflect the effects of the local geology and the conductive substructure related to the complex tectonics of the region not simulated in the model.

  14. Quantitative comparisons of analogue models of brittle wedge dynamics

    NASA Astrophysics Data System (ADS)

    Schreurs, Guido

    2010-05-01

    Analogue model experiments are widely used to gain insights into the evolution of geological structures. In this study, we present a direct comparison of experimental results of 14 analogue modelling laboratories using prescribed set-ups. A quantitative analysis of the results will document the variability among models and will allow an appraisal of reproducibility and limits of interpretation. This has direct implications for comparisons between structures in analogue models and natural field examples. All laboratories used the same frictional analogue materials (quartz and corundum sand) and prescribed model-building techniques (sieving and levelling). Although each laboratory used its own experimental apparatus, the same type of self-adhesive foil was used to cover the base and all the walls of the experimental apparatus in order to guarantee identical boundary conditions (i.e. identical shear stresses at the base and walls). Three experimental set-ups using only brittle frictional materials were examined. In each of the three set-ups the model was shortened by a vertical wall, which moved with respect to the fixed base and the three remaining sidewalls. The minimum width of the model (dimension parallel to mobile wall) was also prescribed. In the first experimental set-up, a quartz sand wedge with a surface slope of ˜20° was pushed by a mobile wall. All models conformed to the critical taper theory, maintained a stable surface slope and did not show internal deformation. In the next two experimental set-ups, a horizontal sand pack consisting of alternating quartz sand and corundum sand layers was shortened from one side by the mobile wall. In one of the set-ups a thin rigid sheet covered part of the model base and was attached to the mobile wall (i.e. a basal velocity discontinuity distant from the mobile wall). In the other set-up a basal rigid sheet was absent and the basal velocity discontinuity was located at the mobile wall. In both types of experiments

  15. Geochemical Characterization Using Geophysical Data and Markov Chain Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hubbard, S.; Rubin, Y.; Murray, C.; Roden, E.; Majer, E.

    2002-12-01

    Although the spatial distribution of geochemical parameters is extremely important for many subsurface remediation approaches, traditional characterization of those parameters is invasive and laborious, and thus is rarely performed sufficiently to describe natural hydrogeological variability at the field-scale. This study is an effort to jointly use multiple sources of information, including noninvasive geophysical data, for geochemical characterization of the saturated and anaerobic portion of the DOE South Oyster Bacterial Transport Site in Virginia. Our data set includes hydrogeological and geochemical measurements from five boreholes and ground-penetrating radar (GPR) and seismic tomographic data along two profiles that traverse the boreholes. The primary geochemical parameters are the concentrations of extractable ferrous iron Fe(II) and ferric iron Fe(III). Since iron-reducing bacteria can reduce Fe(III) to Fe(II) under certain conditions, information about the spatial distributions of Fe(II) and Fe(III) may indicate both where microbial iron reduction has occurred and in which zone it is likely to occur in the future. In addition, as geochemical heterogeneity influences bacterial transport and activity, estimates of the geochemical parameters provide important input to numerical flow and contaminant transport models geared toward bioremediation. Motivated by our previous research, which demonstrated that crosshole geophysical data could be very useful for estimating hydrogeological parameters, we hypothesize in this study that geochemical and geophysical parameters may be linked through their mutual dependence on hydrogeological parameters such as lithofacies. We attempt to estimate geochemical parameters using both hydrogeological and geophysical measurements in a Bayesian framework. Within the two-dimensional study domain (12m x 6m vertical cross section divided into 0.25m x 0.25m pixels), geochemical and hydrogeological parameters were considered as data

  16. Synthesis and receptor profiling of Stemona alkaloid analogues reveal a potent class of sigma ligands

    PubMed Central

    Frankowski, Kevin J.; Setola, Vincent; Evans, Jon M.; Neuenswander, Ben; Roth, Bryan L.; Aubé, Jeffrey

    2011-01-01

    Reported biological activities of Stemona natural products, such as antitussive activity, inspired the development of synthetic methods to access several alkaloids within this family and in so doing develop a general route to the core skeleta shared by the class of natural products. The chemistry was subsequently adapted to afford a series of analogue sets bearing simplified, diverse Stemona-inspired skeleta. Over 100 of these analogues were subjected to general G protein-coupled receptor profiling along with the known antitussive compound, neostenine; this led to the identification of hit compounds targeting several receptor types. The particularly rich hit subset for sigma receptors was expanded with two focused library sets, which resulted in the discovery of a fully synthetic, potent chemotype of sigma ligands. This collaborative effort combined the development of synthetic methods with extensive, flexible screening resources and exemplifies the role of natural products in bioactivity mining. PMID:21368188

  17. Inorganic contaminants from diffuse pollution in shallow groundwater of the Campanian Plain (Southern Italy). Implications for geochemical survey.

    PubMed

    Cuoco, E; Darrah, T H; Buono, G; Verrengia, G; De Francesco, S; Eymold, W K; Tedesco, D

    2015-02-01

    The Campanian Plain (CP) shallow aquifer (Southern Italy) represents a natural laboratory to validate geochemical methods for differentiating diffuse anthropogenic pollution from natural water-rock interaction processes. The CP is an appropriate study area because of numerous potential anthropogenic pollution vectors including agriculture, animal husbandry, septic/drainage sewage systems, and industry. In order to evaluate the potential for geochemical methods to differentiate various contamination vectors, 538 groundwater wells from the shallow aquifer in Campanian Plain (CP) were sampled. The dataset includes both major and trace elements. Natural water-rock interactions, which primarily depend on local lithology, control the majority of geochemical parameters, including most of the major and trace elements. Using prospective statistical methods in combination with the traditional geochemical techniques, we determined the chemical variables that are enriched by anthropogenic contamination (i.e. NO3, SO4 and U) by using NO3 as the diagnostic variable for detecting polluted groundwater. Synthetic agricultural fertilizers are responsible for the majority of SO4 and U pollution throughout the CP area. Both SO4 and U are present in the groundmass of synthetic fertilizers; the uranium concentration is specifically applicable as a tracer for non-point source agricultural fertilizer contamination. The recognition of non-geological (anthropogenic) inputs of these elements has to be considered in the geochemical investigations of contaminated aquifers.

  18. Geochemical surveys in the United States in relation to health.

    USGS Publications Warehouse

    Tourtelot, H.A.

    1979-01-01

    Geochemical surveys in relation to health may be classified as having one, two or three dimensions. One-dimensional surveys examine relations between concentrations of elements such as Pb in soils and other media and burdens of the same elements in humans, at a given time. The spatial distributions of element concentrations are not investigated. The primary objective of two-dimensional surveys is to map the distributions of element concentrations, commonly according to stratified random sampling designs based on either conceptual landscape units or artificial sampling strata, but systematic sampling intervals have also been used. Political units have defined sample areas that coincide with the units used to accumulate epidemiological data. Element concentrations affected by point sources have also been mapped. Background values, location of natural or technological anomalies and the geographic scale of variation for several elements often are determined. Three-dimensional surveys result when two-dimensional surveys are repeated to detect environmental changes. -Author

  19. Seeking a geochemical identifier for authigenic carbonate.

    PubMed

    Zhao, Ming-Yu; Zheng, Yong-Fei; Zhao, Yan-Yan

    2016-01-01

    Authigenic carbonate was recently invoked as a third major global carbon sink in addition to primary marine carbonate and organic carbon. Distinguishing the two carbonate sinks is fundamental to our understanding of Earth's carbon cycle and its role in regulating the evolution of atmospheric oxygen. Here, using microscale geochemical measurements of carbonates in Early Triassic strata, we show that the growth of authigenic carbonate follows a different trajectory from primary marine carbonate in a cross-plot of uranium concentration and carbon isotope composition. Thus, a combination of the two geochemical variables is able to distinguish between the two carbonate sinks. The temporal distribution of authigenic carbonates in the Early Triassic strata suggests that the increase in the extent of carbonate authigenesis acted as a negative feedback to the elevated atmospheric CO2 concentration. PMID:26947562

  20. Seeking a geochemical identifier for authigenic carbonate

    PubMed Central

    Zhao, Ming-Yu; Zheng, Yong-Fei; Zhao, Yan-Yan

    2016-01-01

    Authigenic carbonate was recently invoked as a third major global carbon sink in addition to primary marine carbonate and organic carbon. Distinguishing the two carbonate sinks is fundamental to our understanding of Earth's carbon cycle and its role in regulating the evolution of atmospheric oxygen. Here, using microscale geochemical measurements of carbonates in Early Triassic strata, we show that the growth of authigenic carbonate follows a different trajectory from primary marine carbonate in a cross-plot of uranium concentration and carbon isotope composition. Thus, a combination of the two geochemical variables is able to distinguish between the two carbonate sinks. The temporal distribution of authigenic carbonates in the Early Triassic strata suggests that the increase in the extent of carbonate authigenesis acted as a negative feedback to the elevated atmospheric CO2 concentration. PMID:26947562

  1. Geochemical dynamics in selected Yellowstone hydrothermal features

    NASA Astrophysics Data System (ADS)

    Druschel, G.; Kamyshny, A.; Findlay, A.; Nuzzio, D.

    2010-12-01

    Yellowstone National Park has a wide diversity of thermal features, and includes springs with a range of pH conditions that significantly impact sulfur speciation. We have utilized a combination of voltammetric and spectroscopic techniques to characterize the intermediate sulfur chemistry of Cinder Pool, Evening Primrose, Ojo Caliente, Frying Pan, Azure, and Dragon thermal springs. These measurements additionally have demonstrated the geochemical dynamics inherent in these systems; significant variability in chemical speciation occur in many of these thermal features due to changes in gas supply rates, fluid discharge rates, and thermal differences that occur on second time scales. The dynamics of the geochemical settings shown may significantly impact how microorganisms interact with the sulfur forms in these systems.

  2. Geochemical and isotopic constraints on the tectonic setting of Serra dos Carajas belt, eastern Para, Brazil

    NASA Technical Reports Server (NTRS)

    Olszewski, W. J., Jr.; Gibbs, A. K.; Wirth, K. R.

    1986-01-01

    The lower part of the Serra dos Carajas belt is the metavolcanic and metasedimentary Grao para Group (GPG). The GPG is thought to unconformably overlie the older (but undated) Xingu Complex, composed of medium and high-grade gneisses and amphibolite and greenstone belts. The geochemical data indicate that the GPG has many features in common with ancient and modern volcanic suites erupted through continental crust. The mafic rocks clearly differ from those of most Archean greenstone belts, and modern MORB, IAB, and hot-spot basalts. The geological, geochemical, and isotopic data are all consistent with deposition on continental crust, presumably in a marine basin formed by crustal extension. The isotopic data also suggest the existence of depleted mantle as a source for the parent magmas of the GPG. The overall results suggest a tectonic environment, igneous sources, and petrogenesis similar to many modern continental extensional basins, in contrast to most Archean greenstone belts. The Hammersley basin in Australia and the circum-Superior belts in Canada may be suitable Archean and Proterozoic analogues, respectively.

  3. Synthesizing Earth's geochemical data for hydrogeochemical analysis

    NASA Astrophysics Data System (ADS)

    Brantley, S. L.; Kubicki, J.; Miller, D.; Richter, D.; Giles, L.; Mitra, P.

    2007-12-01

    For over 200 years, geochemical, microbiological, and chemical data have been collected to describe the evolution of the surface earth. Many of these measurements are data showing variations in time or in space. To forward predict hydrologic response to changing tectonic, climatic, or anthropogenic forcings requires synthesis of these data and utilization in hydrogeochemical models. Increasingly, scientists are attempting to synthesize such data in order to make predictions for new regions or for future time periods. However, to make such complex geochemical data accessible requires development of sophisticated cyberinfrastructures that both invite uploading as well as usage of data. Two such cyberinfrastructure (CI) initiatives are currently developing, one to invite and promote the use of environmental kinetics data (laboratory time course data) through ChemxSeer, and the other to invite and promote the use of spatially indexed geochemical data for the Earth's Critical Zone through CZEN.org. The vision of these CI initiatives is to provide cyber-enhanced portals that encourage domain scientists to upload their data before publication (in private cyberspace), and to make these data eventually publicly accessible (after an embargo period). If the CI can be made to provide services to the domain specialist - e.g. to provide data analysis services or data comparison services - we envision that scientists will upload data. In addition, the CI can promote the use and comparison of datasets across disciplines. For example, the CI can facilitate the use of spatially indexed geochemical data by scientists more accustomed to dealing with time-course data for hydrologic flow, and can provide user-friendly interfaces with CI established to facilitate the use of hydrologic data. Examples of the usage of synthesized data to predict soil development over the last 13ky and its effects on active hydrological flow boundaries in surficial systems will be discussed for i) a N

  4. Summary report on geochemical barrier special study

    SciTech Connect

    Not Available

    1988-12-01

    Long-term management of uranium mill tailings must provide assurance that soluble contaminants will not migrate beyond the Point of Compliance. Conventional management alternatives provide containment through the use of physical barriers which are designed to prevent migration of water through the tailings pile. An alternative is to geochemically modify the tailings to immobilize the contaminants. This investigation examined three potential geochemical modifiers to determine their ability to immobilize inorganic groundwater contaminants found in uranium mill tailings. These modifiers were hydrated lime (Ca(OH){sub 2}), limestone (CaCO{sub 3}), and a sphaegnum peat moss. This investigation focused on both the geochemical interactions between the tailings and the modifiers, and the effects the modifiers had on the physical strength of the tailings. The geochemical investigations began with characterization of the tailings by X-ray diffraction and scanning electron microscopy. This was followed by batch leaching experiments in which various concentrations of each modifier were added to tailings in shaker flasks and allowed to come to equilibrium. Finally, column experiments were conducted to simulate flow through a tailings pile. The results show that all of the modifiers were at least moderately effective at immobilizing most of the groundwater contaminants of concern at uranium mill tailings sites. Hydrated lime was able to achieve 90 percent concentration reduction of arsenic, cadmium, selenium, uranium, and sulfate when added at a two percent concentration. Limestone was somewhat less effective and peat removed greater than 90 percent of arsenic, lead, uranium, and sulfate at a one percent concentration. The column tests showed that kinetic and/or mass transfer limitations are important and that sufficient time must be allowed for the immobilization reactions to occur.

  5. Geochemical patterns in the soils of Cyprus.

    PubMed

    Cohen, David R; Rutherford, Neil F; Morisseau, Eleni; Zissimos, Andreas M

    2012-03-15

    The soil geochemical atlas of Cyprus is a recent addition to the series of national to continental-scale geochemical mapping programmes implemented over the last two decades for environmental and resource applications. The study has been conducted at the high sampling density of 1 site per 1km(2), with multi-element and multi-method analysis performed on samples of top soil (0-25cm) and sub soil (50-75cm) from a grid of over 5350 sites across a major portion of Cyprus. Major and most trace elements display sharp concentration changes across the main geological boundaries but a high degree of spatial continuity and consistency of values within those boundaries. Some elements display one to two orders of magnitude difference in median concentrations between the soils developed over ultramafic or mafic units and those developed over sedimentary rocks or alluvial units. The ratio of aqua regia-extractable to total metal contents provides an indication of the general mineralogical host for a number of trace elements. The majority of soils are near-neutral to alkaline with the small proportion of areas with soil pH<5 largely restricted to the major Cu deposits. There is strong correlation between top soil and sub soil geochemical values. Where the concentrations of some elements (including Pb, Hg and Sn) are indicative of contamination, the values are typically higher in the top soil samples in these areas. Variations in the concentration of elements with strong redox controls on mobility are linked to changes in sedimentary environment between deep and shallow marine conditions. Some element patterns can be related to the effects of urbanisation and sulphide mining operations; however the dominant control on soil geochemistry is the parent geology and regolith forming processes. The atlas demonstrates the effectiveness of high-density sampling in mapping local to regional-scale features of the geochemical landscape. PMID:22330424

  6. Geochemical patterns in the soils of Cyprus.

    PubMed

    Cohen, David R; Rutherford, Neil F; Morisseau, Eleni; Zissimos, Andreas M

    2012-03-15

    The soil geochemical atlas of Cyprus is a recent addition to the series of national to continental-scale geochemical mapping programmes implemented over the last two decades for environmental and resource applications. The study has been conducted at the high sampling density of 1 site per 1km(2), with multi-element and multi-method analysis performed on samples of top soil (0-25cm) and sub soil (50-75cm) from a grid of over 5350 sites across a major portion of Cyprus. Major and most trace elements display sharp concentration changes across the main geological boundaries but a high degree of spatial continuity and consistency of values within those boundaries. Some elements display one to two orders of magnitude difference in median concentrations between the soils developed over ultramafic or mafic units and those developed over sedimentary rocks or alluvial units. The ratio of aqua regia-extractable to total metal contents provides an indication of the general mineralogical host for a number of trace elements. The majority of soils are near-neutral to alkaline with the small proportion of areas with soil pH<5 largely restricted to the major Cu deposits. There is strong correlation between top soil and sub soil geochemical values. Where the concentrations of some elements (including Pb, Hg and Sn) are indicative of contamination, the values are typically higher in the top soil samples in these areas. Variations in the concentration of elements with strong redox controls on mobility are linked to changes in sedimentary environment between deep and shallow marine conditions. Some element patterns can be related to the effects of urbanisation and sulphide mining operations; however the dominant control on soil geochemistry is the parent geology and regolith forming processes. The atlas demonstrates the effectiveness of high-density sampling in mapping local to regional-scale features of the geochemical landscape.

  7. Geochemical quantification of semiarid mountain recharge.

    PubMed

    Wahi, Arun K; Hogan, James F; Ekwurzel, Brenda; Baillie, Matthew N; Eastoe, Christopher J

    2008-01-01

    Analysis of a typical semiarid mountain system recharge (MSR) setting demonstrates that geochemical tracers help resolve the location, rate, and seasonality of recharge as well as ground water flowpaths and residence times. MSR is defined as the recharge at the mountain front that dominates many semiarid basins plus the often-overlooked recharge through the mountain block that may be a significant ground water resource; thus, geochemical measurements that integrate signals from all flowpaths are advantageous. Ground water fluxes determined from carbon-14 ((14)C) age gradients imply MSR rates between 2 x 10(6) and 9 x 10(6) m(3)/year in the Upper San Pedro Basin, Arizona, USA. This estimated range is within an order of magnitude of, but lower than, prior independent estimates. Stable isotopic signatures indicate that MSR has a 65% +/- 25% contribution from winter precipitation and a 35% +/- 25% contribution from summer precipitation. Chloride and stable isotope results confirm that transpiration is the dominant component of evapotranspiration (ET) in the basin with typical loss of more than 90% of precipitation-less runoff to ET. Such geochemical constraints can be used to further refine hydrogeologic models in similar high-elevation relief basins and can provide practical first estimates of MSR rates for basins lacking extensive prior hydrogeologic measurements.

  8. Polyamine metabolism in a member of the phylum Microspora (Encephalitozoon cuniculi): effects of polyamine analogues

    PubMed Central

    Bacchi, Cyrus J.; Rattendi, Donna; Faciane, Evangeline; Yarlett, Nigel; Weiss, Louis M.; Frydman, Benjamin; Woster, Patrick; Wei, Benjamin; Marton, Laurence J.; Wittner, Murray

    2011-01-01

    The uptake, biosynthesis and catabolism of polyamines in the microsporidian parasite Encephalitozoon cuniculi are detailed with reference to the effects of oligoamine and arylamine analogues of polyamines. Enc. cuniculi, an intracellular parasite of mammalian cells, has both biosynthetic and catabolic enzymes of polyamine metabolism, as demonstrated in cell-free extracts of mature spores. The uptake of polyamines was measured in immature, pre-emergent spores isolated from host cells by Percoll gradient. Spermine was rapidly taken up and metabolized to spermidine and an unknown, possibly acetamidopropanal, by spermidine/spermine N1-acetyltransferase (SSAT) and polyamine oxidase (PAO). Most of the spermidine and the unknown product were found in the cell incubation medium, indicating they were released from the cell. bis(Ethyl) oligoamine analogues of polyamines, such as SL-11144 and SL-11158, as well as arylamine analogues [BW-1, a bis(phenylbenzyl) 3-7-3 analogue] blocked uptake and interconversion of spermine at micromolar levels and, in the case of BW-1, acted as substrate for PAO. The Enc. cuniculi PAO activity differed from that found in mammalian cells with respect to pH optimum, substrate specificity and sensitivity to known PAO inhibitors. SL-11158 inhibited SSAT activity with a mixed type of inhibition in which the analogue had a 70-fold higher affinity for the enzyme than the natural substrate, spermine. The interest in Enc. cuniculi polyamine metabolism and the biochemical effects of these polyamine analogues is warranted since they cure model infections of Enc. cuniculi in mice and are potential candidates for human clinical trials. PMID:15133083

  9. [The Biological Activity of the Sevanol and Its Analogues].

    PubMed

    Osmakov, D I; Koshelev, S G; Belozerova, O A; Kublitski, V S; Andreev, Ya A; Grishin, E V; Kozlov, S A

    2015-01-01

    Previously, from the plant Thymus armeniacus a new lignan sevanol was isolated, it's structure was elucidated and was shown that it effectively inhibits the acid-sensing channel ASIC3 and also exhibits a pronounced analgesic and anti-inflammatory effect. In this work biological activity of the sevanol analog obtained by chemical synthesis from simple precursors, the stereoisomer of sevanol and a precursor molecule represents a half of sevanol was measured in electrophysiological experiments on human ASIC3 channels expressed in Xenopus laevis oocytes. Measured inhibitory activity of a synthetic analogue coincided with the activity ofthe natural molecule. Stereoisomer showed inhibitory activity drop by about a third part, and the precursor molecule showed much less significant activity. In result the significance of functional groups and a spatial configuration of sevanol in order to biological activity was shown that is important to take into account for the optimal synthesis design as well as for new drugs development on its base. PMID:26762099

  10. Measurement of stimulated Hawking emission in an analogue system.

    PubMed

    Weinfurtner, Silke; Tedford, Edmund W; Penrice, Matthew C J; Unruh, William G; Lawrence, Gregory A

    2011-01-14

    Hawking argued that black holes emit thermal radiation via a quantum spontaneous emission. To address this issue experimentally, we utilize the analogy between the propagation of fields around black holes and surface waves on moving water. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include surface wave horizons. Long waves propagating upstream towards this region are blocked and converted into short (deep-water) waves. This is the analogue of the stimulated emission by a white hole (the time inverse of a black hole), and our measurements of the amplitudes of the converted waves demonstrate the thermal nature of the conversion process for this system. Given the close relationship between stimulated and spontaneous emission, our findings attest to the generality of the Hawking process. PMID:21405217

  11. Synthesis of constrained analogues of tryptophan

    PubMed Central

    Negrato, Marco; Abbiati, Giorgio; Dell’Acqua, Monica

    2015-01-01

    Summary A Lewis acid-catalysed diastereoselective [4 + 2] cycloaddition of vinylindoles and methyl 2-acetamidoacrylate, leading to methyl 3-acetamido-1,2,3,4-tetrahydrocarbazole-3-carboxylate derivatives, is described. Treatment of the obtained cycloadducts under hydrolytic conditions results in the preparation of a small library of compounds bearing the free amino acid function at C-3 and pertaining to the class of constrained tryptophan analogues. PMID:26664620

  12. Platinum analogues in preclinical and clinical development.

    PubMed

    Hamilton, T C; O'Dwyer, P J; Ozols, R F

    1993-11-01

    The impact of cisplatin on chemotherapy for solid tumors has led to the synthesis of many molecules with platinum as their central building block. These so-called platinum analogues have been developed with the obvious goals of improving the antitumor activity of cisplatin and hopefully, at the same time, altering the dose-limiting side effects of the prototype drug. At least 10 such molecules are in clinical development, whereas several others are at various stages of preclinical testing. PMID:8305533

  13. The Brookhaven electron analogue, 1953--1957

    SciTech Connect

    Plotkin, M.

    1991-12-18

    The following topics are discussed on the Brookhaven electron analogue: L.J. Haworth and E.L. VanHorn letters; Original G.K. Green outline for report; General description; Parameter list; Mechanical Assembly; Alignment; Degaussing; Vacuum System; Injection System; The pulsed inflector; RF System; Ferrite Cavity; Pick-up electrodes and preamplifiers; Radio Frequency power amplifier; Lens supply; Controls and Power; and RF acceleration summary.

  14. Blood Loss Estimation Using Gauze Visual Analogue

    PubMed Central

    Ali Algadiem, Emran; Aleisa, Abdulmohsen Ali; Alsubaie, Huda Ibrahim; Buhlaiqah, Noora Radhi; Algadeeb, Jihad Bagir; Alsneini, Hussain Ali

    2016-01-01

    Background Estimating intraoperative blood loss can be a difficult task, especially when blood is mostly absorbed by gauze. In this study, we have provided an improved method for estimating blood absorbed by gauze. Objectives To develop a guide to estimate blood absorbed by surgical gauze. Materials and Methods A clinical experiment was conducted using aspirated blood and common surgical gauze to create a realistic amount of absorbed blood in the gauze. Different percentages of staining were photographed to create an analogue for the amount of blood absorbed by the gauze. Results A visual analogue scale was created to aid the estimation of blood absorbed by the gauze. The absorptive capacity of different gauze sizes was determined when the gauze was dripping with blood. The amount of reduction in absorption was also determined when the gauze was wetted with normal saline before use. Conclusions The use of a visual analogue may increase the accuracy of blood loss estimation and decrease the consequences related to over or underestimation of blood loss. PMID:27626017

  15. Blood Loss Estimation Using Gauze Visual Analogue

    PubMed Central

    Ali Algadiem, Emran; Aleisa, Abdulmohsen Ali; Alsubaie, Huda Ibrahim; Buhlaiqah, Noora Radhi; Algadeeb, Jihad Bagir; Alsneini, Hussain Ali

    2016-01-01

    Background Estimating intraoperative blood loss can be a difficult task, especially when blood is mostly absorbed by gauze. In this study, we have provided an improved method for estimating blood absorbed by gauze. Objectives To develop a guide to estimate blood absorbed by surgical gauze. Materials and Methods A clinical experiment was conducted using aspirated blood and common surgical gauze to create a realistic amount of absorbed blood in the gauze. Different percentages of staining were photographed to create an analogue for the amount of blood absorbed by the gauze. Results A visual analogue scale was created to aid the estimation of blood absorbed by the gauze. The absorptive capacity of different gauze sizes was determined when the gauze was dripping with blood. The amount of reduction in absorption was also determined when the gauze was wetted with normal saline before use. Conclusions The use of a visual analogue may increase the accuracy of blood loss estimation and decrease the consequences related to over or underestimation of blood loss.

  16. Controls on OIB and MORB Geochemical Variabilty

    NASA Astrophysics Data System (ADS)

    Shorttle, O.; Maclennan, J.

    2014-12-01

    The geochemical variability preserved in Ocean Island and Mid-ocean ridge basalt (MORB) is a key tracer of the magmatic storage and transport processes they experience during their ascent through the mantle and crust. The effect of these processes is to collapse the huge diversity of melt compositions predicted to form during polybaric fractional melting of a lithologically heterogeneous mantle, into the narrow range we see expressed in most ocean island and mid-ocean ridge settings. Magma mixing can therefore be seen as contaminating the variance structure of primitive mantle melts, akin to the way in which wall-rock assimilation contaminates melts by chemical addition. The key observation from the melt inclusion and whole-rock records from ocean islands such as Iceland, is that as crystallisation proceeds mixing in magma chambers progressively reduces geochemical variability, until by ~5wt% MgO almost all primary chemical diversity has been lost. These chemical systematics allow us to extend the observations made at ocean islands to make predictions about how mixing processes should operate in MORB generally and the key factors controlling mixing efficiency: melt flow out of the mantle, crustal thickness, magma supply rate, and by extension spreading rate, and mantle potential temperature. However, with its low sampling density, the global MORB database does not easily allow testing of these hypotheses. We have developed a novel geospatial statistical analysis to bridge the gap between observations made on a small scale - at single ocean islands and ridge segments - to the entire global dataset of MORB chemistry. By analysing the geochemical variance in MORB over a range of bandwidths we have captured the ~200km lengthscale at which the simple relationships between geochemical variability and MgO appear. Our results demonstrate that on short lengthscales mantle chemical structure and magmatic processes operate coherently in destruction of geochemical variability

  17. Geochemical evolution of groundwater beneath Mexico City

    NASA Astrophysics Data System (ADS)

    Edmunds, W. M.; Carrillo-Rivera, J. J.; Cardona, A.

    2002-02-01

    The geochemical evolution of groundwaters along a 24 km flow beneath Central Mexico City path from the Sierra de las Cruces towards Lake Texcoco has been investigated using stable isotopes, radiocarbon and major and trace elements to determine the natural baseline conditions, the extent of any contamination and the effectiveness of the overlying aquitard seal. Modern groundwaters of low salinity (<200 mg l -1) are found up to 11 km from the outcrop area and groundwater ages of up to 6000 yr BP occur in the middle part of the section. Groundwater stable isotope ratios δ18O and δ2H lie close to the global meteoric water line, indicating that the groundwater originates from local rainfall. The groundwater chemistry may be interpreted as the result of inputs from the source area with progressive water-rock interaction down the horizontal flow gradient. A redox boundary is found at 9 km along the line of section, coincident with the start of the confined section. Relatively low nitrate concentrations (below 9 mg l -1 NO 3-N) are found in the aerobic waters; low concentrations of NO 3 in the aerobic waters and low Cl reflect inputs prior to the modern development. Some elements (Cr, U, As, Se, Sb) increase their concentration with distance (time) as far as the redox boundary, but low concentrations occur in the reducing aquifer section. The chemistry of several major ions (Mg, Na/Cl, K) as well as trace elements such as Li, Rb, Ba reflect the weathering of the basaltic mineral assemblage (feldspars and mafic minerals) and their increases are generally proportional to residence time; phosphate, F and I concentrations indicate a probable source from apatite in the basaltic or rhyolitic rocks. A borehole in the east of the city (some 17 km downgradient) intercepted thermal water (Si geothermometry indicates 163°C at depth). This water gives a distinctive composition indicating possible addition of metamorphic CO 2 which has then reacted with the igneous rocks. Increases

  18. Geochemical characteristics of an urban river: Geochemical contamination and urban stream syndrome

    NASA Astrophysics Data System (ADS)

    MacAvoy, S. E.; Connor, N.; Sarraino, S.; Frantz, D.; Bushaw-Newton, K. L.

    2013-12-01

    The Anacostia River in Washington, D.C. is among the 10 most contaminated rivers in the USA, containing sewage, metals, PAHs, and PCBs. The biogeochemical characteristics of urban rivers, including the Anacostia, remain largely unstudied. Here we examine the base-flow geochemistry of the tidal freshwater Anacostia over a two-year period (April 2010- April 2012), concentrating on water chemistry (pH, hardness, SAR, alkalinity, Ca, Mg, Na, K, Fe, Mn, Zn, Al, Ba, Ni, P, S, Sr, NO3, NH4, PO4) at 3 locations in the stream. Mean NO3was generally between 1.1 and 1.3 mg/L, although occasionally concentrations increased to 3-4 mg/L at all sites. NH4 was very low generally (0.0 to 0.3 mg/L) with occasional peaks of 1.5-3.9 mg/L downstream. A Principle Components Analysis of stream chemistry showed that the upstream site had two components that explained 34.2 and 29.2% of the data variance; PC1 was most strongly negatively correlated with Ca (-.896), Mg (-.585) and hardness (-.823), and was positively correlated with Ba (which is sometimes associated with disturbance), B, NO3, P, PO4, Sr and Al. PC2 was strongly correlated with Mg, K, S, Ni and NH4. Na was positively and significantly correlated with both components, but more so with PC1. At the middle and downstream sites, two components explained 41 to 44% (PC1) and 22 to 28% (PC2) of the data set variance respectively. The components were essentially the same as the upstream site, with the dominance switched. PC1 was positively and highly correlated with ions associated with bedrock components (Ca, Mg, K, Na, and pH but also S and NH4). PC2 was not positively correlated with any of the dominant geochemical variables, but was negatively correlated with Ca and K and positively correlated with NO3, Ba and Mn. The principle components analysis suggests that there is a strong geochemical component and weaker anion/nitrate component contributing to the ion distribution, and their relative dominance changes moving downstream

  19. Geochemical analysis of layered outcrops using laser-induced breakdown spectroscopy (LIBS) - Implications for Mars exploration

    NASA Astrophysics Data System (ADS)

    Sobron, P.; Lefebvre, C.; Leveille, R. J.; Koujelev, A.; Haltigin, T.; Hongwei, D.; Wang, A.; Cabrol, N. A.; Zacny, K.; Craft, J.

    2012-12-01

    The chemistry and the stratigraphy of sedimentary, evaporative, and other types of deposits are indicators of their depositional environment and climate, and the evolution of these over time. Over the past eight years, the Mars Exploration Rovers (MER) have investigated several outcrops at Meridiani Planum and Gusev Crater. Compared to the MER, the capabilities of Curiosity to investigate outcrops and other deposits are enhanced because the rover incorporates a stand-off laser-induced breakdown spectroscopy (LIBS) instrument within the ChemCam suite. ChemCam's LIBS instrument has the capability to obtain chemical information from a large variety of targets at various distances, up to 7 m, including targets at a distance within stratigraphic layers non-accessible to other payload elements. In this work we demonstrate that semi-quantitative chemical stratigraphy can be very rapidly obtained by performing LIBS measurements on visually distinct layers within an outcrop at a terrestrial Mars analogue: the Atacama Desert, Chile. Such semi-quantitative chemical stratigraphy provides very valuable information on the distribution of elements within the analyzed layers, which can be used for tactical mission planning purposes. We performed laboratory laser-induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy measurement on field samples from a layered outcrop from the Atacama Desert, Chile. This layered outcrop is a good terrestrial morphological analogue for similar formations that will likely be investigated by the Mars Science Laboratory on Gale crater. Our results demonstrate that LIBS can generate semi-quantitative chemical profiles in less than 1 min using automated data processing tools, and therefore the LIBS instrument can become an invaluable tactical tool on MSL for rapid geochemical survey of layered outcrops. The derived chemical profile at the terrestrial analogue is consistent with the range of minerals identified by Raman spectroscopy. In the

  20. A geochemical sampling technique for use in areas of active alpine glaciation: an application from the central Alaska Range

    USGS Publications Warehouse

    Stephens, G.C.; Evenson, E.B.; Detra, D.E.

    1990-01-01

    In mountainous regions containing extensive glacier systems there is a lack of suitable material for conventional geochemical sampling. As a result, in most geochemical sampling programs a few stream-sediment samples collected at, or near, the terminus of valley glaciers are used to evaluate the mineral potential of the glaciated area. We have developed and tested a technique which utilizes the medial moraines of valley glaciers for systematic geochemical exploration of the glacial catchment area. Moraine sampling provides geochemical information that is site-specific in that geochemical anomalies can be traced directly up-ice to bedrock sources. Traverses were made across the Trident and Susitna glaciers in the central Alaska Range where fine-grained (clay to sand size) samples were collected from each medial moraine. These samples were prepared and chemically analyzed to determine the concentration of specific elements. Fifty pebbles were collected at each moraine for archival purposes and for subsequent lithologic identification. Additionally, fifty cobbles and fifty boulders were examined and described at each sample site to determine the nature and abundance of lithologies present in the catchment area, the extent and nature of visible mineralization, the presence and intensity of hydrothermal alteration and the existence of veins, dikes and other minor structural features. Results from the central Alaska Range have delineated four distinct multi-element anomalies which are a response to potential mineralization up-ice from the medial moraine traverse. By integrating the lithologic, mineralogical and geochemical data the probable geological setting of the geochemical anomalies is determined. ?? 1990.

  1. The costal landslide from analogue experiments: perspectives and limitation

    NASA Astrophysics Data System (ADS)

    Del Ventisette, C.; Nolesini, T.; Moretti, S.; Fanti, R.

    2010-12-01

    Understanding the triggering mechanism of coastal landslides (triggered and/or developed at air-water interface) and their evolution is fundamental to evaluate their hazard and, predicting the energy, the associated tsunami risk. The aim of this work is to verify the suitability of analogue modelling to understand the triggering mechanism and the evolution of landslide along the costal line. As a starting case study the Sciara del Fuoco (SdF), northwest flank of the volcanic island of Stromboli (Italy), was chosen. The analogue modelling technique has been proven to represent an useful tool to understand many geological processes, as it allows studying the progressive deformation, providing also useful indications about the role of distinct factors controlling the final deformation pattern. The models simulated at a first approximation the geological geometries observed at Stromboli, a composite volcano forming the northernmost island of the Aeolian Archipelago (Tyrrhenian Sea). The activity of Stromboli volcano is characterized by a persistent mild explosive activity at the summit craters sporadically interrupted by episodes of lava effusion and violent paroxysmal explosions as in 2002-2003 and in 2007. During the 2002 effusion a large landslide occurred on the SdF. The landslide caused a tsunami, which produced severe damages along the island shores. A series of analogue models was performed to investigate the influence of two different types of triggering mechanism and the behaviour of landslides both in air and air-water interface: 1) surface bulging due to the intrusion of a dike; 2) accumulation of material due to an uppermost landslide or due to opening of a new vent. The models, constructed in a Plexiglas tank, were scaled to the natural prototype following the geometrical, rheological, kinematical and dynamical similarities (e.g. Hubbert, 1937; Ramberg, 1981). The modelling material (Fontainbleau sand and rice) was sieved on a slope, inclination of which

  2. Fixed-fugacity option for the EQ6 geochemical reaction path code

    SciTech Connect

    Delany, J.M.; Wolery, T.J.

    1984-12-20

    EQ3/6 is a software package used to model aqueous geochemical systems. The EQ6 code allows reaction paths of dynamic systems to be calculated. This report describes a new option for the EQ6 computer program that permits the fugacity of any gas in the EQ6 data base to be set to a fixed value. This capability permits simulation of the effect of rapid chemical exchange with a large external gas reservoir by allowing the user to fix the fugacities of selected gas species. Geochemical environments such as groundwater systems open to the atmosphere (e.g., the unsaturated zone), natural aqueous systems that form closed systems at depth, and experimental systems that use controlled atmospheres can be modeled. Two of the principal geochemical weathering agents, CO{sub 2} and O{sub 2}, are the most likely gas species for which this type of exchange may be important. An example of the effect of constant CO{sub 2} fugacity on both open and closed systems is shown for the case of albite dissolution (NaAlSi{sub 3}O{sub 8}) in distilled water. This example demonstrates that the effects of imposed fugacities on geochemical systems can be considerable. This computer code is used in the Nevada Nuclear Waste Storage Investigations Project. 15 refs., 8 figs.

  3. A geochemical atlas of South Carolina--an example using data from the National Geochemical Survey

    USGS Publications Warehouse

    Sutphin, David M.

    2005-01-01

    National Geochemical Survey data from stream-sediment and soil samples, which have been analyzed using consistent methods, were used to create maps, graphs, and tables that were assembled in a consistent atlas format that characterizes the distribution of major and trace chemical elements in South Carolina. Distribution patterns of the elements in South Carolina may assist mineral exploration, agriculture, waste-disposal-siting issues, health, environmental, and other studies. This atlas is an example of how data from the National Geochemical Survey may be used to identify general or regional patterns of elemental occurrences and to provide a snapshot of element concentration in smaller areas.

  4. A geochemical perspective of Red Mountain: an unmined volcanogenic massive sulfide deposit in the Alaska Range

    USGS Publications Warehouse

    Giles, Stuart A.; Eppinger, Robert G.

    2014-01-01

    The U.S. Geological Survey (USGS) has investigated the environmental geochemistry of a group of unmined volcanogenic massive sulfide (VMS) deposits in the Bonnifield mining district, Alaska Range, east-central Alaska. The spectacularly colored Red Mountain deposit is the best exposed of these and provides excellent baseline geochemical data for natural environmental impacts of acidic rock drainage, metal dissolution and transport, and acidic salt and metal precipitation from an exposed and undisturbed VMS deposit.

  5. A dual-color far-red to near-infrared firefly luciferin analogue designed for multiparametric bioluminescence imaging.

    PubMed

    Jathoul, Amit P; Grounds, Helen; Anderson, James C; Pule, Martin A

    2014-11-24

    Red-shifted bioluminescent emitters allow improved in vivo tissue penetration and signal quantification, and have led to the development of beetle luciferin analogues that elicit red-shifted bioluminescence with firefly luciferase (Fluc). However, unlike natural luciferin, none have been shown to emit different colors with different luciferases. We have synthesized and tested the first dual-color, far-red to near-infrared (nIR) emitting analogue of beetle luciferin, which, akin to natural luciferin, exhibits pH dependent fluorescence spectra and emits bioluminescence of different colors with different engineered Fluc enzymes. Our analogue produces different far-red to nIR emission maxima up to λ(max)=706 nm with different Fluc mutants. This emission is the most red-shifted bioluminescence reported without using a resonance energy transfer acceptor. This improvement should allow tissues to be more effectively probed using multiparametric deep-tissue bioluminescence imaging.

  6. [Synthesis, conformation, and spectroscopy of nucleoside analogues concerning their antiviral activity].

    PubMed

    Kuśmierek, Jarosław T; Stolarski, Ryszard

    2015-01-01

    Chemically modified analogues of nucleosides and nucleotides, have been thoroughly investigated since the discovery of DNA double helix by Watson and Crick in 1953 (Nature 171: 737). Chemical structures, first of all tautomerism, of the nucleic acid bases, as well as the conformations of the nucleic acids constituents, determine the secondary and tertiary structures of DNA and RNA polymers. Similarly, structural and dynamic parameters of nucleoside derivatives determine their biological activity in mutagenesis, neoplastic transformation, as well as antiviral or anticancer properties. In this review, a multidisciplinary approach of Prof. David Shugar's group is presented in the studies on nucleosides and nucleotides. It consists in chemical syntheses of suitable analogues, measurements of physicochemical and spectral parameters, conformational analysis by means of nuclear magnetic resonance (NMR) and X-ray diffraction, as well as characteristics of the nucleoside analogues as inhibitors of some selected, target enzymes, crucial in respect to antiviral activity of the analogues. These long-lasting studies follows upon the line of the main paradigm of molecular biophysics, i. e. structure-activity relationship. PMID:26677575

  7. Using Geochemical Indicators to Distinguish High Biogeochemical Activity in Sediments

    NASA Astrophysics Data System (ADS)

    Kenwell, A. M.; Navarre-Sitchler, A.; Prugue, R.; Spear, J. R.; Williams, K. H.; Maxwell, R. M.

    2014-12-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict elevated rates of biogeochemical activity (microbial "hotspots") in subsurface environments by correlating microbial community structure with the spatial distribution of geochemical indicators in subsurface sediments. Statistical hierarchical cluster analyses (HCA) of X-ray fluorescence (XRF), simulated precipitation leachate, bioavailable Fe and Mn, total organic carbon (TOC), microbial community structure, grain size, bulk density and moisture content data were used to identify regions of the subsurface characterized by biogeochemical hotspots and sample characteristics indicative of these hotspots within fluvially-derived aquifer sediments. The methodology has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 33 sediment samples were taken from 8 sediment cores and at the East River 33 soil/sediment samples were collected across and perpendicular to 3 active meanders. The East River watershed exhibits characteristic fluvial progression and serves as a representative example of many headwater catchments with the upper Colorado River basin. Initial clustering revealed that operationally defined hotspots were characterized by high organic carbon, bioavailable iron and dark colors but not necessarily low hydraulic conductivity. Applying the method to identify hotspots in both contaminated and natural floodplain deposits and their associated alluvial aquifers demonstrates the broad applicability of a geochemical indicator based approach.

  8. DNA-based methods of geochemical prospecting

    DOEpatents

    Ashby, Matthew

    2011-12-06

    The present invention relates to methods for performing surveys of the genetic diversity of a population. The invention also relates to methods for performing genetic analyses of a population. The invention further relates to methods for the creation of databases comprising the survey information and the databases created by these methods. The invention also relates to methods for analyzing the information to correlate the presence of nucleic acid markers with desired parameters in a sample. These methods have application in the fields of geochemical exploration, agriculture, bioremediation, environmental analysis, clinical microbiology, forensic science and medicine.

  9. A Geochemical Speciation Program Based on PHREEQE

    1992-02-18

    HARPHRQ is a program based on the code PHREEQE and is designed to model geochemical reactions. Like PHREEQE, it can calculate the pH, redox potential and mass transfer as a function of reaction progress and the composition of solution in equilibrium with multiple phases. In addition, HARPHRQ includes options to allow the composition of a solution at a fixed pH to be calculated and to automatically add or remove mineral phases as they become saturatedmore » or exhausted. A separate module can also be interfaced to give a choice of sorption models including the triple-layer model.« less

  10. Effect of gonadotropin-releasing hormone analogue on thermal nociception in mice.

    PubMed

    Bobyntsev, I I; Sever'yanova, L A; Kryukov, A A

    2006-02-01

    Intraperitoneal treatment with an analogue of gonadotropin-releasing hormone in doses of 0.004-450 microg/kg produced an analgesic effect on male mice in the hot plate test. Castration significantly elevated the nociceptive thresholds. In castrated mice the effects of the test peptide were less pronounced and had an algesic nature. Our results indicate that these effects depend on functional activity of the hypothalamic-pituitary-gonadal axis.

  11. The structure, synthesis, and immunomodulating activity of bacterial lipopeptides and their analogues

    NASA Astrophysics Data System (ADS)

    Ousanova, Mariya P.; Sebyakin, Yurii L.

    1997-10-01

    The current state and prospects for the use of natural lipopeptides and their synthetic analogues in the study of fine mechanisms of functioning of complex biological systems and in the solution of various problems of biochemistry and medicine are considered. The results of investigations related to the synthesis and biological activity of lipopeptides are summarised. The data on the application of lipopeptides as components of synthetic vaccines and antitumour drugs are discussed. The bibliography includes 71 references.

  12. Digitoxin Analogues with Improved Anticytomegalovirus Activity

    PubMed Central

    2014-01-01

    Cardiac glycosides are potent inhibitors of cancer cell growth and possess antiviral activities at nanomolar concentrations. In this study we evaluated the anticytomegalovirus (CMV) activity of digitoxin and several of its analogues. We show that sugar type and sugar length attached to the steroid core structure affects its anticytomegalovirus activity. Structure–activity relationship (SAR) studies identified the l-sugar containing cardiac glycosides as having improved anti-CMV activity and may lead to better understanding of how these compounds inhibit CMV replication. PMID:24900847

  13. Materials analogue of zero-stiffness structures

    NASA Astrophysics Data System (ADS)

    Kumar, Arun; Subramaniam, Anandh

    2011-04-01

    Anglepoise lamps and certain tensegrities are examples of zero-stiffness structures. These structures are in a state of neutral equilibrium with respect to changes in configuration of the system. Using Eshelby's example of an edge dislocation in a thin plate that can bend, we report the discovery of a non-trivial new class of material structures as an analogue to zero-stiffness structures. For extended positions of the edge dislocation in these structures, the dislocation experiences a zero image force. Salient features of these material structures along with the key differences from conventional zero-stiffness structures are pointed out.

  14. Spectroscopic study of solar twins and analogues

    NASA Astrophysics Data System (ADS)

    Datson, Juliet; Flynn, Chris; Portinari, Laura

    2015-02-01

    Context. Many large stellar surveys have been and are still being carried out, providing huge amounts of data, for which stellar physical parameters will be derived. Solar twins and analogues provide a means to test the calibration of these stellar catalogues because the Sun is the best-studied star and provides precise fundamental parameters. Solar twins should be centred on the solar values. Aims: This spectroscopic study of solar analogues selected from the Geneva-Copenhagen Survey (GCS) at a resolution of 48 000 provides effective temperatures and metallicities for these stars. We test whether our spectroscopic parameters, as well as the previous photometric calibrations, are properly centred on the Sun. In addition, we search for more solar twins in our sample. Methods: The methods used in this work are based on literature methods for solar twin searches and on methods we developed in previous work to distinguish the metallicity-temperature degeneracies in the differential comparison of spectra of solar analogues versus a reference solar reflection spectrum. Results: We derive spectroscopic parameters for 148 solar analogues (about 70 are new entries to the literature) and verify with a-posteriori differential tests that our values are well-centred on the solar values. We use our dataset to assess the two alternative calibrations of the GCS parameters; our methods favour the latest revision. We show that the choice of spectral line list or the choice of asteroid or time of observation does not affect the results. We also identify seven solar twins in our sample, three of which are published here for the first time. Conclusions: Our methods provide an independent means to differentially test the calibration of stellar catalogues around the values of a well-known benchmark star, which makes our work interesting for calibration tests of upcoming Galactic surveys. Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 077.D

  15. CO2 Removal using a Synthetic Analogue of Carbonic Anhydrase

    SciTech Connect

    Cordatos, Harry

    2010-09-14

    Project attempts to develop a synthetic analogue for carbonic anhydrase and incorporate it in a membrane for separation of CO2 from coal power plant flue gas. Conference poster presents result of first 9 months of project progress including concept, basic system architecture and membrane properties target, results of molecular modeling for analogue - CO2 interaction, and next steps of testing analogue resistance to flue gas contaminants.

  16. Geochemical baseline distribution of harmful elements in the surface soils of Campania region.

    NASA Astrophysics Data System (ADS)

    Albanese, Stefano; Lima, Annamaria; Qu, Chengkai; Cicchella, Domenico; Buccianti, Antonella; De Vivo, Benedetto

    2015-04-01

    Environmental geochemical mapping has assumed an increasing relevance and the separation of values to discriminate between anthropogenic pollution and natural (geogenic) sources has become crucial to address environmental problems affecting the quality of life of human beings. In the last decade, a number of geochemical prospecting projects, mostly focused on surface soils (topsoils), were carried out at different scales (from regional to local) across the whole Campania region (Italy) to characterize the distribution of both harmful elements and persistent organic pollutants (POP) in the environment and to generating a valuable database to serve as reference in developing geomedical studies. During the 2014, a database reporting the distribution of 53 chemical elements in 3536 topsoil samples, collected across the whole region, was completed. The geochemical data, after necessary quality controls, were georeferenced and processed in a geochemistry dedicated GIS software named GEODAS. For each considered element a complete set of maps was generated to depict both the discrete and the spatially continuous (interpolated) distribution of elemental concentrations across the region. The interpolated maps were generated using the Multifractal Inverse Distance eighted (MIDW) algorithm. Subsequently, the S-A method, also implemented in GEODAS, was applied to MIDW maps to eliminate spatially limited anomalies from the original grid and to generate the distribution patterns of geochemical baselines for each element. For a selected group of elements geochemical data were also treated by means of a Compositional Data Analysis (CoDA) aiming at investigating the regionalised structure of the data by considering the joint behaviour of several elements constituting for each sample its whole composition. A regional environmental risk assessment was run on the basis of the regional distribution of heavy metals in soil, land use types and population. The risk assessment produced a

  17. Evaluation of Geochemical Fracture Conductivity Alterations in Shale under Laboratory Conditions

    NASA Astrophysics Data System (ADS)

    Radonjic, M.; Olabode, A.

    2015-12-01

    . The result indicated that rock-fluid geochemical interactions can constrict natural fracture conductivity under CO2 sequestration conditions. This diagenetic accretions can lead to significant improvement in the seal integrity of shaly caprocks.

  18. GEMAS: Geochemical Distribution of Cadmium in European Soil

    NASA Astrophysics Data System (ADS)

    Birke, Manfred; Reimann, Clemens; Demetriades, Alecos; Dinelli, Enrico; Halamić, Josip; Rauch, Uwe; Gosar, Mateja; Ladenberger, Anna; Klos, Volodymyr; De Vivo, Benedetto

    2014-05-01

    Cadmium concentrations are reported for the <2 mm fraction of soil samples from agricultural (Ap, 0-20 cm, N=2108) and grazing land (Gr, 0-10 cm, N=2024) covering 33 European countries, and 5.6 million km2 at a sample density of 1 sample per 2500 km2 in two different extractions, i.e., aqua regia and mobile metal ion (MMI®) and determined by ICP-MS. The median value of Cd in aqua regia extraction is 0.181 mg/kg in the Ap and 0.202 mg/kg in the Gr samples.The regional Cd distribution in the Ap and Gr samples appears similar. The pattern dominating the Cd maps is the southern limit of the last glaciation, as well as the clay content in the European agricultural soil. In Scandinavia, a relationship to the Caledonian structural lineaments can be recognised in the distribution pattern; in eastern Europe, it is the boundary between Palaeozoic cover and Mesozoic platform sediments that stands out. The data for the aqua regia extraction establish the natural geochemical background of Cd concentrations in European agricultural and grazing land soil; they demonstrate the existence of two major natural background regimes, a northern and a southern European, seperated by the Trans-European Suture Zone. Most of the Cd anomalies in European agricultural and grazing land soil can be linked to geological (parent material and mineralisation) sources. In several areas, the natural anomaly pattern is overprinted by anthropogenic emissions from old mining, and the ore processing and metal industries in the same region. For a more detailed separation of geogenic and anthropogenic anomalous Cd concentrations, higher density geochemical mapping or a multivariate statistical data analysis are needed. Only a few Cd anomalies could be attributed to predominantly anthropogenic sources, such as urbanisation and use of fertilisers. The median value of Cd in the mobile metal ion (MMI®) extraction of Ap soil samples is 0.054 mg/kg. The Cd distribution pattern of MMI® extracts shows a zone of

  19. Geochemical orientation for mineral exploration in the Hashemite Kingdom of Jordan

    USGS Publications Warehouse

    Overstreet, W.C.; Grimes, D.J.; Seitz, J.F.

    1982-01-01

    This report is a supplement to previous accounts of geochemical exploration conducted in the Hashemite Kingdom of Jordan by the Natural Resources Authority of the Royal Government of Jordan and the U.S. Geological Survey. The field work on which this report is based was sponsored by the U.S. Agency for International Development, U.S. Department of State. Procedures used in collecting various kinds of rocks, ores, slags, eluvial and alluvial sediments, heavy-mineral concentrates, and organic materials for use as geochemical sample media are summarized, as are the laboratory procedures followed for the analysis of these sample materials by semiquantitative spectrographic, atomic absorption, fluorometric, and X-ray diffraction methods. Geochemical evaluations of the possibilities for economic mineral deposits in certain areas are presented. The results of these preliminary investigations open concepts for further use in geochemical exploration in the search for metallic mineral deposits in Jordan. Perhaps the most desirable new activity would be hydrogeochemical exploration for uranium and base metals, accompanied by interpretation of such remote-sensing data as results of airborne radiometric surveys and computer-enhanced LANDSAT imagery. For more conventional approaches to geochemical exploration, however, several fundamental problems regarding proper choice of geochemical sample media for different geologic and geographic parts of the Country must be solved before effective surveys can be made. The present results also show that such common geochemical exploration techniques as the determination of the trace-element contents of soils, plant ash, and slags have direct application also toward the resolution of several archaeological problems in Jordan. These include the relation of trace-elements chemistry of local soils to the composition of botanic remains, the trace-elements composition of slags to the technological development of the extractive metallurgy of

  20. Geochemical controls on groundwater chemistry in shales

    SciTech Connect

    Von Damm, K.L.

    1989-01-01

    The chemistry of groundwaters is one of the most important parameters in determining the mobility of species within a rock formation. A three pronged approach was used to determine the composition of, and geochemical controls, on groundwaters specifically within shale formations: (1) available data were collected from the literature, the US Geological Survey WATSTORE data base, and field sampling, (2) the geochemical modeling code EQ3/6 was used to simulate interaction of various shales and groundwaters, and (3) several types of shale were reacted with synthetic groundwaters in the laboratory. The comparison of model results to field and laboratory data provide a means of validating the models, as well as a means of deconvoluting complex field interactions. Results suggest that groundwaters in shales have a wide range in composition and are primarily of the Na-Cl-HCO/sub 3/- type. The constancy of the Na:Cl (molar) ratio at 1:1 and the Ca:Mg ratio from 3:1 to 1:1 suggests the importance of halite and carbonates in controlling groundwater compositions. In agreement with the reaction path modeling, most of the groundwaters are neutral to slightly alkaline at low temperatures. Model and experimental results suggest that reaction (1) at elevated temperatures, or (2) in the presence of oxygen will lead to more acidic conditions. Some acetate was found to be produced in the experiments; depending on the constraints applied, large amounts of acetate were produced in the model results. 13 refs., 1 tab.

  1. Archean crust-mantle geochemical differentiation

    NASA Technical Reports Server (NTRS)

    Tilton, G. R.

    1983-01-01

    Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

  2. Is formamide a geochemically plausible prebiotic solvent?

    PubMed

    Bada, Jeffrey L; Chalmers, John H; Cleaves, H James

    2016-07-27

    From a geochemical perspective, significant amounts of pure formamide (HCONH2) would have likely been rare on the early Earth. There may have been mixed formamide-water solutions, but even in the presence of catalyst, solutions with >20 weight% water in formamide would not have produced significant amounts of prebiotic compounds. It might be feasible to produce relatively pure formamide by a rare occurrence of freezing formamide/water mixtures at temperatures lower than formamide's freezing point (2.55 °C) but greater than the freezing point of water. Because of the high density of formamide ice it would have sunk and accumulated at the bottom of the solution. If the remaining water froze on the surface of this ice, and was then removed by a sublimation-ablation process, a small amount of pure formamide ice might have been produced. In addition a recent report suggested that ∼85 weight% formamide could be prepared by a geochemical type of fractional distillation process, offering another possible route for prebiotic formamide production. PMID:27253848

  3. A geochemical atlas of North Carolina, USA

    USGS Publications Warehouse

    Reid, J.C.

    1993-01-01

    A geochemical atlas of North Carolina, U.S.A., was prepared using National Uranium Resource Evaluation (NURE) stream-sediment data. Before termination of the NURE program, sampling of nearly the entire state (48,666 square miles of land area) was completed and geochemical analyses were obtained. The NURE data are applicable to mineral exploration, agriculture, waste disposal siting issues, health, and environmental studies. Applications in state government include resource surveys to assist mineral exploration by identifying geochemical anomalies and areas of mineralization. Agriculture seeks to identify areas with favorable (or unfavorable) conditions for plant growth, disease, and crop productivity. Trace elements such as cobalt, copper, chromium, iron, manganese, zinc, and molybdenum must be present within narrow ranges in soils for optimum growth and productivity. Trace elements as a contributing factor to disease are of concern to health professionals. Industry can use pH and conductivity data for water samples to site facilities which require specific water quality. The North Carolina NURE database consists of stream-sediment samples, groundwater samples, and stream-water analyses. The statewide database consists of 6,744 stream-sediment sites, 5,778 groundwater sample sites, and 295 stream-water sites. Neutron activation analyses were provided for U, Br, Cl, F, Mn, Na, Al, V, Dy in groundwater and stream water, and for U, Th, Hf, Ce, Fe, Mn, Na, Sc, Ti, V, Al, Dy, Eu, La, Sm, Yb, and Lu in stream sediments. Supplemental analyses by other techniques were reported on U (extractable), Ag, As, Ba, Be, Ca, Co, Cr, Cu, K, Li, Mg, Mo, Nb, Ni, P, Pb, Se, Sn, Sr, W, Y, and Zn for 4,619 stream-sediment samples. A small subset of 334 stream samples was analyzed for gold. The goal of the atlas was to make available the statewide NURE data with minimal interpretation to enable prospective users to modify and manipulate the data for their end use. The atlas provides only

  4. In search of future earths: assessing the possibility of finding Earth analogues in the later stages of their habitable lifetimes.

    PubMed

    O'Malley-James, Jack T; Greaves, Jane S; Raven, John A; Cockell, Charles S

    2015-05-01

    Earth will become uninhabitable within 2-3 Gyr as a result of the increasing luminosity of the Sun changing the boundaries of the habitable zone (HZ). Predictions about the future of habitable conditions on Earth include declining species diversity and habitat extent, ocean loss, and changes to geochemical cycles. Testing these predictions is difficult, but the discovery of a planet that is an analogue to future Earth could provide the means to test them. This planet would need to have an Earth-like biosphere history and to be approaching the inner edge of the HZ at present. Here, we assess the possibility of finding such a planet and discuss the benefits of analyzing older Earths. Finding an old-Earth analogue in nearby star systems would be ideal, because this would allow for atmospheric characterization. Hence, as an illustrative example, G stars within 10 pc of the Sun are assessed as potential old-Earth-analog hosts. Six of these represent good potential hosts. For each system, a hypothetical Earth analogue is placed at locations within the continuously habitable zone (CHZ) that would allow enough time for Earth-like biosphere development. Surface temperature evolution over the host star's main sequence lifetime (assessed by using a simple climate model) is used to determine whether the planet would be in the right stage of its late-habitable lifetime to exhibit detectable biosignatures. The best candidate, in terms of the chances of planet formation in the CHZ and of biosignature detection, is 61 Virginis. However, planet formation studies suggest that only a small fraction (0.36%) of G stars in the solar neighborhood could host an old-Earth analogue. If the development of Earth-like biospheres is rare, requiring a sequence of low-probability events to occur, biosphere evolution models suggest they are rarer still, with only thousands being present in the Galaxy as a whole. PMID:25984921

  5. In search of future earths: assessing the possibility of finding Earth analogues in the later stages of their habitable lifetimes.

    PubMed

    O'Malley-James, Jack T; Greaves, Jane S; Raven, John A; Cockell, Charles S

    2015-05-01

    Earth will become uninhabitable within 2-3 Gyr as a result of the increasing luminosity of the Sun changing the boundaries of the habitable zone (HZ). Predictions about the future of habitable conditions on Earth include declining species diversity and habitat extent, ocean loss, and changes to geochemical cycles. Testing these predictions is difficult, but the discovery of a planet that is an analogue to future Earth could provide the means to test them. This planet would need to have an Earth-like biosphere history and to be approaching the inner edge of the HZ at present. Here, we assess the possibility of finding such a planet and discuss the benefits of analyzing older Earths. Finding an old-Earth analogue in nearby star systems would be ideal, because this would allow for atmospheric characterization. Hence, as an illustrative example, G stars within 10 pc of the Sun are assessed as potential old-Earth-analog hosts. Six of these represent good potential hosts. For each system, a hypothetical Earth analogue is placed at locations within the continuously habitable zone (CHZ) that would allow enough time for Earth-like biosphere development. Surface temperature evolution over the host star's main sequence lifetime (assessed by using a simple climate model) is used to determine whether the planet would be in the right stage of its late-habitable lifetime to exhibit detectable biosignatures. The best candidate, in terms of the chances of planet formation in the CHZ and of biosignature detection, is 61 Virginis. However, planet formation studies suggest that only a small fraction (0.36%) of G stars in the solar neighborhood could host an old-Earth analogue. If the development of Earth-like biospheres is rare, requiring a sequence of low-probability events to occur, biosphere evolution models suggest they are rarer still, with only thousands being present in the Galaxy as a whole.

  6. Synthesis of "neoprofen", a rigidified analogue of ibuprofen, exemplifying synthetic methodology for altering the 3-D topology of pharmaceutical substances.

    PubMed

    Ramsubhag, Ron R; Massaro, Chelsea L; Dadich, Christina M; Janeczek, Andrew J; Hoang, Tung T; Mazzio, Elizabeth A; Eyunni, Suresh; Soliman, Karam F A; Dudley, Gregory B

    2016-08-16

    3,3-Dimethylcyclopentanes (neopentylenes) are ubiquitous in Nature but largely absent from synthetic pharmaceutical libraries. Neopentylenes define a hydrophobic and rigid 3-D topology with distinct molecular pharmacology, as exemplified here with two neopentylene-fused analogues of the synthetic anti-inflammatory drug, ibuprofen. PMID:27492587

  7. Diversity-oriented synthesis of analogues of the novel macrocyclic peptide FR-225497 through late stage functionalization

    PubMed Central

    Mukherjee, Jyotiprasad; Sil, Suman

    2015-01-01

    Summary A concise synthetic approach to a class of biologically interesting cyclic tetrapeptides is reported which involves a late-stage functionalization of a macrocyclic scaffold through cross metathesis in an attempt to create diversity. The utility of this protocol is demonstrated through the preparation of three structural analogues of the important naturally occurring histone deacetylase inhibitor FR-225497. PMID:26734096

  8. Design, synthesis, and biological evaluation of novel analogues of archazolid: a highly potent simplified V-ATPase inhibitor.

    PubMed

    Menche, Dirk; Hassfeld, Jorma; Sasse, Florenz; Huss, Markus; Wieczorek, Helmut

    2007-03-15

    Novel analogues of the V-ATPase inhibitors archazolid A and B with modifications of the free hydroxyl groups and the side chain were designed by molecular modeling, synthesized by derivatization of the parent natural product and evaluated for V-ATPase inhibition and growth inhibition of murine connective tissue cells.

  9. Self-Powered Analogue Smart Skin.

    PubMed

    Shi, Mayue; Zhang, Jinxin; Chen, Haotian; Han, Mengdi; Shankaregowda, Smitha A; Su, Zongming; Meng, Bo; Cheng, Xiaoliang; Zhang, Haixia

    2016-04-26

    The progress of smart skin technology presents unprecedented opportunities for artificial intelligence. Resolution enhancement and energy conservation are critical to improve the perception and standby time of robots. Here, we present a self-powered analogue smart skin for detecting contact location and velocity of the object, based on a single-electrode contact electrification effect and planar electrostatic induction. Using an analogue localizing method, the resolution of this two-dimensional smart skin can be achieved at 1.9 mm with only four terminals, which notably decreases the terminal number of smart skins. The sensitivity of this smart skin is remarkable, which can even perceive the perturbation of a honey bee. Meanwhile, benefiting from the triboelectric mechanism, extra power supply is unnecessary for this smart skin. Therefore, it solves the problems of batteries and connecting wires for smart skins. With microstructured poly(dimethylsiloxane) films and silver nanowire electrodes, it can be covered on the skin with transparency, flexibility, and high sensitivity. PMID:27010713

  10. Magnetohydrodynamical Analogue of a Black Hole

    NASA Astrophysics Data System (ADS)

    Zamorano, Nelson; Asenjo, Felipe

    2014-03-01

    We study the conditions that a plasma fluid and its container should meet to generate a magneto-acoustic horizon. This effect becomes an alternative to the analogue black hole found in a transonic fluid flow setting. In this context we use the magnetohydrodynamic formalism (MHD) to analyze the evolution of an irrotational plasma fluid interacting with an external constant magnetic field. Under certain plausible approximations, the dynamic of the field perturbations is described by a scalar field potential that follows a second order differential equation. As we prove here, this equation corresponds to the wave equation associated to a scalar field in a curved space-time. This horizon emerges when the local speed of the medium grows larger than the sound velocity. The magnetic field generates an effective pressure which contributes to the magneto-acoustic speed. We compare these results with the known physics of analogue black holes. We will also refer to our ongoing experiment that, in its first stage, attempts to reproduce the wave horizons found in an open channel with an obstacle: PRL 106, 021302 (2011).

  11. The effect of scale on the interpretation of geochemical anomalies

    USGS Publications Warehouse

    Theobald, P.K.; Eppinger, R.G.; Turner, R.L.; Shiquan, S.

    1991-01-01

    The purpose of geochemical surveys changes with scale. Regional surveys identify areas where mineral deposits are most likely to occur, whereas intermediate surveys identify and prioritize specific targets. At detailed scales specific deposit models may be applied and deposits delineated. The interpretation of regional geochemical surveys must take into account scale-dependent difference in the nature and objectives of this type of survey. Overinterpretation of regional data should be resisted, as should recommendations to restrict intermediate or detailed follow-up surveys to the search for specific deposit types or to a too limited suite of elements. Regional surveys identify metallogenic provinces within which a variety of deposit types and metals are most likely to be found. At intermediate scale, these regional provinces often dissipate into discrete clusters of anomalous areas. At detailed scale, individual anomalous areas reflect local conditions of mineralization and may seem unrelated to each other. Four examples from arid environments illustrate the dramatic change in patterns of anomalies between regional and more detailed surveys. On the Arabian Shield, a broad regional anomaly reflects the distribution of highly differentiated anorogenic granites. A particularly prominent part of the regional anomaly includes, in addition to the usual elements related to the granites, the assemblage of Mo, W and Sn. Initial interpretation suggested potential for granite-related, stockwork Mo deposits. Detailed work identified three separate sources for the anomaly: a metal-rich granite, a silicified and stockwork-veined area with scheelite and molybdenite, and scheelite/powellite concentrations in skarn deposits adjacent to a ring-dike complex. Regional geochemical, geophysical and remote-sensing data in the Sonoran Desert, Mexico, define a series of linear features interpreted to reflect fundamental, northeast-trending fractures in the crust that served as the prime

  12. Mechanistic Insights from the Binding of Substrate and Carbocation Intermediate Analogues to Aristolochene Synthase

    PubMed Central

    Chen, Mengbin; Al-lami, Naeemah; Janvier, Marine; D'Antonio, Edward L.; Faraldos, Juan A.; Cane, David E.; Allemann, Rudolf K.; Christianson, David W.

    2013-01-01

    Aristolochene synthase, a metal-dependent sesquiterpene cyclase from Aspergillus terreus, catalyzes the ionization-dependent cyclization of farnesyl diphosphate (FPP) to form the bicyclic eremophilane (+)-aristolochene with perfect structural and stereochemical precision. Here, we report the X-ray crystal structure of aristolochene synthase complexed with three Mg2+ ions and the unreactive substrate analogue farnesyl-S-thiolodiphosphate (FSPP), showing that the substrate diphosphate group is anchored by metal coordination and hydrogen bond interactions identical to those previously observed in the complex with three Mg2+ ions and inorganic pyrophosphate (PPi). Moreover, the binding conformation of FSPP directly mimics that expected for productively bound FPP, with the exception of the precise alignment of the C-S bond with regard to the C10-C11 π system that would be required for C1-C10 bond formation in the first step of catalysis. We also report crystal structures of aristolochene synthase complexed with Mg2+3-PPi and ammonium or iminium analogues of bicyclic carbocation intermediates proposed for the natural cyclization cascade. Various binding orientations are observed for these bicyclic analogues, and these orientations appear to be driven by favorable electrostatic interactions between the positively charged ammonium group of the analogue and the negatively charged PPi anion. Surprisingly, the active site is sufficiently flexible to accommodate analogues with partially or completely incorrect stereochemistry. Although this permissiveness in binding is unanticipated, based on the stereochemical precision of catalysis that leads exclusively to the (+)-aristolochene stereoisomer, it suggests the ability of the active site to enable controlled reorientation of intermediates during the cyclization cascade. Taken together, these structures illuminate important aspects of the catalytic mechanism. PMID:23905850

  13. Paleoproterozoic Kimozero kimberlite (Karelian Craton): Geological setting and geochemical typing

    NASA Astrophysics Data System (ADS)

    Kargin, A. V.; Babarina, I. I.; Bogatikov, O. A.; Yutkina, E. V.; Kondrashov, I. A.

    2015-11-01

    Geological and structural mapping of Paleoproterozoic Kimozero kimberlite with account for lithological facies and geochemical specialization provides evidence for the multiphase structure of the kimberlite pipe, which underwent fragmentation as a result of shear-faulting deformations. Two geochemical types of kimberlite (magnesium and carbonate) are distinguished.

  14. Identification and Separation of Geochemical Distribution Patterns using Fractal/Multifractal Methods

    NASA Astrophysics Data System (ADS)

    Liu, Yue; Cheng, Qiuming

    2015-04-01

    Identification and separation of anomalies from background for mineral exploration or environmental assessment is a fundamental issue in the field of exploration geochemistry. Traditionally, geochemical data are usually considered to follow normal or lognormal distributions, this scenario might lead to the extreme values cannot be detected by ordinary statistic methods, because the data of interest cannot meet the prerequisites of some typical statistic methods, and usually it is hard to separate geochemical anomalies from background, especially when weak anomalies are hidden in high background or the difference between anomaly and background is feeble. Cheng (2000) demonstrated that background values of geochemical data typically followed normal or lognormal distributions, and and anomalous values usually followed fractal/multifractal distributions. West and Shlesinger (1990) investigated the relationships of normal/lognormal distributions with Pareto distributions, the results indicated that the natural system was gradually tend to complexity from normal distributions to lognormal distributions, and then to Pareto distributions. Pareto distributions describe the most complex natural system, showing stronger fractal/multifractal characteristics. From the perspective of ore-forming processes, ore formation is the result of complex physical and chemical processes, there are considerable overlaps between igneous and hydrothermal and between sedimentary and hydrothermal, as a result, complex ore-forming processes might result in fractal/multifractal pattern. In the present study, a case study of anomaly identification of REE mineralization- related La and Y concentration values from 1617 stream sediment samples in the Nanling belt, South China, is used to demonstrate the application of two fractal/multifractal methods, singularity analysis and concentration-area (C-A) fractal method. First, singularity analysis is used to identify weak anomalies hidden within

  15. Bioisosteric Exchange of Csp3 -Chloro and Methyl Substituents: Synthesis and Initial Biological Studies of Atpenin A5 Analogues.

    PubMed

    Krautwald, Simon; Nilewski, Christian; Mori, Mihoko; Shiomi, Kazuro; Ōmura, Satoshi; Carreira, Erick M

    2016-03-14

    Asymmetric synthesis and initial biological studies of two analogues of a naturally occurring chlorinated antifungal agent, atpenin A5, are described. These analogues were selected on the basis of Cl→CH3 or H3 C→Cl exchanges in the side-chain of atpenin A5. The interchange of chloro and methyl substituents led to complex II inhibitors with equal IC50 values. This suggests that Cl↔Me bioisosteric exchange can be realized in aliphatic settings. PMID:26891236

  16. Geochemical Evidence for a Terrestrial Magma Ocean

    NASA Technical Reports Server (NTRS)

    Agee, Carl B.

    1999-01-01

    The aftermath of phase separation and crystal-liquid fractionation in a magma ocean should leave a planet geochemically differentiated. Subsequent convective and other mixing processes may operate over time to obscure geochemical evidence of magma ocean differentiation. On the other hand, core formation is probably the most permanent, irreversible part of planetary differentiation. Hence the geochemical traces of core separation should be the most distinct remnants left behind in the mantle and crust, In the case of the Earth, core formation apparently coincided with a magma ocean that extended to a depth of approximately 1000 km. Evidence for this is found in high pressure element partitioning behavior of Ni and Co between liquid silicate and liquid iron alloy, and with the Ni-Co ratio and the abundance of Ni and Co in the Earth's upper mantle. A terrestrial magma ocean with a depth of 1000 km will solidify from the bottom up and first crystallize in the perovskite stability field. The largest effect of perovskite fractionation on major element distribution is to decrease the Si-Mg ratio in the silicate liquid and increase the Si-Mg ratio in the crystalline cumulate. Therefore, if a magma ocean with perovskite fractionation existed, then one could expect to observe an upper mantle with a lower than chondritic Si-Mg ratio. This is indeed observed in modern upper mantle peridotites. Although more experimental work is needed to fully understand the high-pressure behavior of trace element partitioning, it is likely that Hf is more compatible than Lu in perovskite-silicate liquid pairs. Thus, perovskite fractionation produces a molten mantle with a higher than chondritic Lu-Hf ratio. Arndt and Blichert-Toft measured Hf isotope compositions of Barberton komatiites that seem to require a source region with a long-lived, high Lu-Hf ratio. It is plausible that that these Barberton komatiites were generated within the majorite stability field by remelting a perovskite

  17. Selected Geochemical Data for Modeling Near-Surface Processes in Mineral Systems

    USGS Publications Warehouse

    Giles, Stuart A.; Granitto, Matthew; Eppinger, Robert G.

    2009-01-01

    The database herein was initiated, designed, and populated to collect and integrate geochemical, geologic, and mineral deposit data in an organized manner to facilitate geoenvironmental mineral deposit modeling. The Microsoft Access database contains data on a variety of mineral deposit types that have variable environmental effects when exposed at the ground surface by mining or natural processes. The data tables describe quantitative and qualitative geochemical analyses determined by 134 analytical laboratory and field methods for over 11,000 heavy-mineral concentrate, rock, sediment, soil, vegetation, and water samples. The database also provides geographic information on geology, climate, ecoregion, and site contamination levels for over 3,000 field sites in North America.

  18. Central Colorado Assessment Project - Application of integrated geologic, geochemical, biologic, and mineral resource studies

    USGS Publications Warehouse

    Klein, T.L.; Church, S.E.; Caine, J.S.; Schmidt, T.S.; deWitt, E.H.

    2008-01-01

    Cooperative studies by USDA Forest Service, National Park Service supported by the USGS Mineral Resources Program (MRP), and National Cooperative Geologic Mapping Programs (NCGMP) contributed to the mineral-resource assessment and included regional geologic mapping at the scale 1:100,000, collection and geochemical studies of stream sediments, surface water, and bedrock samples, macroinvertebrate and biofilm studies in the riparian environment, remote-sensing studies, and geochronology. Geoscience information available as GIS layers has improved understanding of the distribution of metallic, industrial, and aggregate resources, location of areas that have potential for their discovery or development, helped to understand the relation of tectonics, magmatism, and paleohydrology to the genesis of the metal deposits in the region, and provided insight on the geochemical and environmental effects that historical mining and natural, mineralized rock exposures have on surface water, ground water, and aquatic life.

  19. Geochemical features of the elemental composition of meadowsweet (Filipendula ulmaria (L).Maxim) in Kemerovo Oblast

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. A.; Sobolev, I. S.; Baranovskaya, N. V.; Kolesnikova, E. A.; Chernenkaya, E. V.; Yalaltdinova, A. R.

    2016-09-01

    Biogeochemical sampling of the aboveground part of meadowsweet (Fillipendula Ulmaria (L). Maxim) allowed us to study ecological and geochemical features of 10 regions in Kemerovo Oblast, including both natural and man-made landscapes. The content of 55 elements in the plant is determined by ICP-MS. Statistical analysis of the results allowed us to establish the effect of the soil mineral composition and the mining region specificity on the elemental composition of meadowsweet, to reveal significant positive correlations of the elements and to establish a statistically significant difference in the studied areas on the basis of the content of some elements. Sample reference to one of the clusters, followed by an assessment of their geochemical features is determined by the K-average method.

  20. Geochemical and microbiological assessment of groundwater status: a case study

    NASA Astrophysics Data System (ADS)

    Preziosi, E.; Del Bon, A.; Amalfitano, S.; Fazi, S.; Zoppini, A.; Parrone, D.; Ghergo, S.

    2012-04-01

    The qualitative status of the groundwater resources is drawing increasingly attention in relation to the requirements of the European legislative framework. The monitoring strategies are developed by considering the chemical processes affecting groundwater quality. However, despite the use of biological indicators is a common practice for the qualitative assessment of surface waters, a similar approach is hardly being taken into account by policy makers for ground waters. Aquifers are key environments due to the ecosystem capability to ameliorate water quality, e.g. through the natural biodegradation of chemical contaminants. The objective of this research was to characterize a porous water table aquifer from a geochemical and microbiological point of view, aiming to link the hydrogeochemical properties to distribution patterns of the free-living microbial communities. The broader perspective is to integrate the role of microorganisms in the groundwater evolution processes, with new insights in the knowledge of the different microbial communities inhabiting different aquifer typologies. Moreover, microbiological parameters that could be used as a valuable indicator of groundwater quality are sought. A field-scale analysis was performed along the southern Sabatini Mounts aquifer (Central Italy, 50 sampling sites), in an area of about 340 square km, where Pleistocene volcanic products overlay Pleistocene gravel and silt-clay layers, the latter being much more widespread in the downgradient part of the study area. The selected aquifer is contaminated by natural origin elements such as arsenic and fluoride, as well as by human activities, both diffuse (agriculture) and localized, especially in the downgradient part of the aquifer (e.g. landfills, quarries, oil deposits). The main physicochemical parameters of ground waters were determined in situ (redox status, pH, conductivity, T, DO, alkalinity) and in laboratory by ionic chromatography and mass spectrometry (major

  1. Space Analogue Environments: Are the Populations Comparable?

    NASA Astrophysics Data System (ADS)

    Sandal, G. M.

    Background: Much of our present understanding about psychology in space is based on studies of groups operating in so-called analogue environments where personnel are exposed to many of the same stressors as those experienced by astronauts in space. One possible problem with extrapolating results is that personnel operating in various hazardous and confined environments might differ in characteristics influencing coping, interaction, and performance. The object of this study was to compare the psychological similarity of these populations in order to get a better understanding of whether this extrapolation is justifiable. The samples investigated include polar crossings (N= 22), personnel on Antarctic research stations (N= 183), several military occupations (N= 187), and participants in space simulation studies (N=20). Methods: Personnel in each of these environments were assessed using the Personality Characteristic Inventory (PCI) and Utrecht Coping List (UCL). The PCI is a multidimensional trait assessment battery that measures various aspects of achievement orientation and social competence. The UCL is a questionnaire designed to assess habitual coping strategies when encountering stressful or demanding situations. Results: Only minor differences in use of habitual coping strategies were evident across the different samples. In relation to personality scores, the military subjects and participants in space simulation studies indicated higher competitiveness and negative instrumentality compared to both the personnel on Antarctic research stations and participants in polar expedition. Among the personnel on Antarctic research stations, significant gender differences were found with women scoring lower on competitiveness, negative instrumentality and impatience/irritability. Compared to the other samples, the participants in polar expeditions were found to be more homogeneous in personality and no significant gender differences were evident on the traits that

  2. Starting a European Space Agency Sample Analogue Collection for Robotic Exploration Missions

    NASA Astrophysics Data System (ADS)

    Smith, C. L.; Mavris, C.; Michalski, J. R.; Rumsey, M. S.; Russell, S. S.; Jones, C.; Schroeven-Deceuninck, H.

    2015-12-01

    The Natural History Museum is working closely with the European Space Agency (ESA) and the UK Space Agency to develop a European collection of analogue materials with appropriate physical/mechanical and chemical (mineralogical) properties which can support the development and verification of both spacecraft and scientific systems for potential science and exploration missions to Phobos/Deimos, Mars, C-type asteroids and the Moon. As an ESA Collection it will be housed at the ESA Centre based at Harwell, UK. The "ESA Sample Analogues Collection" will be composed of both natural and artificial materials chosen to (as closely as possible) replicate the surfaces and near-surfaces of different Solar System target bodies of exploration interest. The analogue samples will be fully characterised in terms of both their physical/mechanical properties (compressive strength, bulk density, grain shape, grain size, cohesion and angle of internal friction) and their chemical/mineralogical properties (texture, modal mineralogy, bulk chemical composition - major, minor and trace elements and individual mineralogical compositions). The Collection will be fully curated to international standards including implementation of a user-friendly database and will be available for use by engineers and scientists across the UK and Europe. Enhancement of the initial Collection will be possible through collaborations with other ESA and UK Space Agency supported activities, such as the acquisition of new samples during field trials.

  3. Starting a European Space Agency Sample Analogue Collection for Robotic Exploration Missions

    NASA Astrophysics Data System (ADS)

    Sherwood Lollar, B.; Sutcliffe, C. N.; Ballentine, C. J.; Onstott, T. C.; Lau, C. Y. M.; Magnabosco, C.; Slater, G.; Moser, D. P.

    2014-12-01

    The Natural History Museum is working closely with the European Space Agency (ESA) and the UK Space Agency to develop a European collection of analogue materials with appropriate physical/mechanical and chemical (mineralogical) properties which can support the development and verification of both spacecraft and scientific systems for potential science and exploration missions to Phobos/Deimos, Mars, C-type asteroids and the Moon. As an ESA Collection it will be housed at the ESA Centre based at Harwell, UK. The "ESA Sample Analogues Collection" will be composed of both natural and artificial materials chosen to (as closely as possible) replicate the surfaces and near-surfaces of different Solar System target bodies of exploration interest. The analogue samples will be fully characterised in terms of both their physical/mechanical properties (compressive strength, bulk density, grain shape, grain size, cohesion and angle of internal friction) and their chemical/mineralogical properties (texture, modal mineralogy, bulk chemical composition - major, minor and trace elements and individual mineralogical compositions). The Collection will be fully curated to international standards including implementation of a user-friendly database and will be available for use by engineers and scientists across the UK and Europe. Enhancement of the initial Collection will be possible through collaborations with other ESA and UK Space Agency supported activities, such as the acquisition of new samples during field trials.

  4. The geochemical record in rock glaciers

    USGS Publications Warehouse

    Steig, E.J.; Fitzpatrick, J.J.; Potter, N.; Clark, D.H.

    1998-01-01

    A 9.5 m ice core was extracted from beneath the surficial debris cover of a rock glacier at Galena Creek, northwestern Wyoming. The core contains clean, bubble-rich ice with silty debris layers spaced at roughly 20 cm intervals. The debris layers are similar in appearance to those in typical alpine glaciers, reflecting concentration of debris by melting at the surface during the summer ablation season. Profiles of stable isotope concentrations and electrical conductivity measurements provide independent evidence for melting in association with debris layers. These observations are consistent with a glacial origin for the ice, substantiating the glacigenic model for rock glacier formation. The deuterium excess profile in the ice indicates that the total depth of meltwater infiltration is less than the thickness of one annual layer, suggesting that isotope values and other geochemical signatures are preserved at annual resolution. This finding demonstrates the potential for obtaining useful paleoclimate information from rock glacier ice.

  5. A geochemical basis for endomyocardial fibrosis.

    PubMed

    Valiathan, M S; Kartha, C C; Panday, V K; Dang, H S; Sunta, C M

    1986-09-01

    In a search for geochemical factors that could play a role in the pathogenesis of tropical endomyocardial fibrosis, endomyocardial tissue samples obtained from patients at necropsy or operation were analysed for major elements present in laterite and monazite, which are important soil constituents of Kerala State of India. Atomic absorption spectrophotometry was used for detecting iron, silicon, aluminium, zinc, magnesium, calcium, sodium, potassium, and manganese and neutron activation analysis for thorium. Compared with control samples from victims of fatal accidents, an excess of thorium, sodium, and calcium and a deficiency of magnesium were present in samples from patients. It has been shown earlier that the staple diets of people in Kerala have high concentrations of thorium, and these data show that thorium can become concentrated in cardiac tissues. It is speculated that thorium excess in conjunction with magnesium deficiency may play a role in the causation of tropical endomyocardial fibrosis. PMID:3791358

  6. A geochemical basis for endomyocardial fibrosis.

    PubMed

    Valiathan, M S; Kartha, C C; Panday, V K; Dang, H S; Sunta, C M

    1986-09-01

    In a search for geochemical factors that could play a role in the pathogenesis of tropical endomyocardial fibrosis, endomyocardial tissue samples obtained from patients at necropsy or operation were analysed for major elements present in laterite and monazite, which are important soil constituents of Kerala State of India. Atomic absorption spectrophotometry was used for detecting iron, silicon, aluminium, zinc, magnesium, calcium, sodium, potassium, and manganese and neutron activation analysis for thorium. Compared with control samples from victims of fatal accidents, an excess of thorium, sodium, and calcium and a deficiency of magnesium were present in samples from patients. It has been shown earlier that the staple diets of people in Kerala have high concentrations of thorium, and these data show that thorium can become concentrated in cardiac tissues. It is speculated that thorium excess in conjunction with magnesium deficiency may play a role in the causation of tropical endomyocardial fibrosis.

  7. Antidepressant-like effects and mechanisms of flavonoids and related analogues.

    PubMed

    Guan, Li-Ping; Liu, Bing-Yu

    2016-10-01

    Flavonoids, possessing a basic phenylbenzopyrone core, are important components of the human diet, and are found in many medicinal plants. Flavonoids include chalcones, flavanones and their derivatives. Synthetic and natural isolated flavonoids display an enormous number of biological activities such as antitumor, antiplatelet, anti-malarial, anti-inflammatory, antidepressant and anticonvulsant properties. This review article focuses on the antidepressant-like effect, structure-activity relationship and mechanism of action of total flavonoid extracts isolation from natural sources, flavonoid compounds and their related analogues. PMID:27214511

  8. Code System to Model Aqueous Geochemical Equilibria.

    2001-08-23

    Version: 00 MINTEQ is a geochemical program to model aqueous solutions and the interactions of aqueous solutions with hypothesized assemblages of solid phases. It was developed for the Environmental Protection Agency to perform the calculations necessary to simulate the contact of waste solutions with heterogeneous sediments or the interaction of ground water with solidified wastes. MINTEQ can calculate ion speciation/solubility, adsorption, oxidation-reduction, gas phase equilibria, and precipitation/dissolution ofsolid phases. MINTEQ can accept a finite massmore » for any solid considered for dissolution and will dissolve the specified solid phase only until its initial mass is exhausted. This ability enables MINTEQ to model flow-through systems. In these systems the masses of solid phases that precipitate at earlier pore volumes can be dissolved at later pore volumes according to thermodynamic constraints imposed by the solution composition and solid phases present. The ability to model these systems permits evaluation of the geochemistry of dissolved traced metals, such as low-level waste in shallow land burial sites. MINTEQ was designed to solve geochemical equilibria for systems composed of one kilogram of water, various amounts of material dissolved in solution, and any solid materials that are present. Systems modeled using MINTEQ can exchange energy and material (open systems) or just energy (closed systems) with the surrounding environment. Each system is composed of a number of phases. Every phase is a region with distinct composition and physically definable boundaries. All of the material in the aqueous solution forms one phase. The gas phase is composed of any gaseous material present, and each compositionally and structurally distinct solid forms a separate phase.« less

  9. Solution Processed PEDOT Analogues in Electrochemical Supercapacitors.

    PubMed

    Österholm, Anna M; Ponder, James F; Kerszulis, Justin A; Reynolds, John R

    2016-06-01

    We have designed fully soluble ProDOTx-EDOTy copolymers that are electrochemically equivalent to electropolymerized PEDOT without using any surfactants or dispersants. We show that these copolymers can be incorporated as active layers in solution processed thin film supercapacitors to demonstrate capacitance, stability, and voltage similar to the values of those that use electrodeposited PEDOT as the active material with the added advantage of the possibility for large scale, high-throughput processing. These Type I supercapacitors provide exceptional cell voltages (up to 1.6 V), highly symmetrical charge/discharge behavior, promising long-term stability exceeding 50 000 charge/discharge cycles, as well as energy (4-18 Wh/kg) and power densities (0.8-3.3 kW/kg) that are comparable to those of electrochemically synthesized analogues. PMID:27195798

  10. Jupiter analogues and planets of active stars

    NASA Astrophysics Data System (ADS)

    Kürster, M.; Zechmeister, M.; Endl, M.; Lo Curto, G.; Hartman, H.; Nilsson, H.; Henning, T.; Hatzes, A. P.; Cochran, W. D.

    2013-04-01

    Combined results are now available from a 15 year long search for Jupiter analogues around solar-type stars using the ESO CAT + CES, ESO 3.6 m + CES, and ESO 3.6 m + HARPS instruments. They comprise planet (co-)discoveries (ι Hor and HR 506) and confirmations (three planets in HR 3259) as well as non-confirmations of planets (HR 4523 and ɛ Eri) announced elsewhere. A long-term trend in ɛ Ind found by our survey is probably attributable to a Jovian planet with a period >30 yr, but we cannot fully exclude stellar activity effects as the cause. A 3.8 year periodic variation in HR 8323 can be attributed to stellar activity.

  11. Carbon and silicate grains in the laboratory as analogues of cosmic dust.

    PubMed

    Mennella, V; Brucato, J R; Colangeli, L

    2001-03-15

    Carbon and silicate grains are the two main components of cosmic dust. There is increasing spectroscopic evidence that their composition varies according to the cosmic environment and the experienced processing. Irradiation from ultraviolet photons and cosmic rays, as well as chemical interactions with the interstellar gas play a crucial role for grain transformation. The study of 'laboratory analogues' represents a powerful tool to better understand the nature and evolution of cosmic materials. In particular, simulations of grain processing are fundamental to outline an evolutionary pathway for interstellar particles. In the present work, we discuss the ultraviolet and infrared spectral changes induced by thermal annealing, ultraviolet irradiation, ion irradiation and hydrogen atom bombardment in carbon and silicate analogue materials. The laboratory results give the opportunity to shed light on the long-standing problems of the attribution of ultraviolet and infrared interstellar spectral features.

  12. Structural Insights Lead to a Negamycin Analogue with Improved Antimicrobial Activity against Gram-Negative Pathogens

    PubMed Central

    2015-01-01

    Negamycin is a natural product with antibacterial activity against a broad range of Gram-negative pathogens. Recent revelation of its ribosomal binding site and mode of inhibition has reinvigorated efforts to identify improved analogues with clinical potential. Translation-inhibitory potency and antimicrobial activity upon modification of different moieties of negamycin were in line with its observed ribosomal binding conformation, reaffirming stringent structural requirements for activity. However, substitutions on the N6 amine were tolerated and led to N6-(3-aminopropyl)-negamycin (31f), an analogue showing 4-fold improvement in antibacterial activity against key bacterial pathogens. This represents the most potent negamycin derivative to date and may be a stepping stone toward clinical development of this novel antibacterial class. PMID:26288696

  13. Design and synthesis of novel arctigenin analogues for the amelioration of metabolic disorders.

    PubMed

    Duan, Shudong; Huang, Suling; Gong, Jian; Shen, Yu; Zeng, Limin; Feng, Ying; Ren, Wenming; Leng, Ying; Hu, Youhong

    2015-04-01

    Analogues of the natural product (-)-arctigenin, an activator of adenosine monophosphate activated protein kinase, were prepared in order to evaluate their effects on 2-deoxyglucose uptake in L6 myotubes and possible use in ameliorating metabolic disorders. Racemic arctigenin 2a was found to display a similar uptake enhancement as does (-)-arctigenin. As a result, the SAR study was conducted utilizing racemic compounds. The structure-activity relationship study led to the discovery of key substitution patterns on the lactone motif that govern 2-deoxyglucose uptake activities. The results show that replacement of the para-hydroxyl group of the C-2 benzyl moiety of arctigenin by Cl has a pronounced effect on uptake activity. Specifically, analogue 2p, which contains the p-Cl substituent, stimulates glucose uptake and fatty acid oxidation in L6 myotubes.

  14. Design and Synthesis of Novel Arctigenin Analogues for the Amelioration of Metabolic Disorders

    PubMed Central

    2015-01-01

    Analogues of the natural product (−)-arctigenin, an activator of adenosine monophosphate activated protein kinase, were prepared in order to evaluate their effects on 2-deoxyglucose uptake in L6 myotubes and possible use in ameliorating metabolic disorders. Racemic arctigenin 2a was found to display a similar uptake enhancement as does (−)-arctigenin. As a result, the SAR study was conducted utilizing racemic compounds. The structure–activity relationship study led to the discovery of key substitution patterns on the lactone motif that govern 2-deoxyglucose uptake activities. The results show that replacement of the para-hydroxyl group of the C-2 benzyl moiety of arctigenin by Cl has a pronounced effect on uptake activity. Specifically, analogue 2p, which contains the p-Cl substituent, stimulates glucose uptake and fatty acid oxidation in L6 myotubes. PMID:25941553

  15. Synthesis of Firefly Luciferin Analogues and Evaluation of the Luminescent Properties.

    PubMed

    Ioka, Shuji; Saitoh, Tsuyoshi; Iwano, Satoshi; Suzuki, Koji; Maki, Shojiro A; Miyawaki, Atsushi; Imoto, Masaya; Nishiyama, Shigeru

    2016-06-27

    Five new firefly luciferin (1) analogues were synthesized and their light emission properties were examined. Modifications of the thiazoline moiety in 1 were employed to produce analogues containing acyclic amino acid side chains (2-4) and heterocyclic rings derived from amino acids (5 and 6) linked to the benzothiazole moiety. Although methyl esters of all of the synthetic derivatives exhibited chemiluminescence activity, only carboluciferin (6), possessing a pyrroline-substituted benzothiazole structure, had bioluminescence (BL) activity (λmax =547 nm). Results of bioluminescence studies with AMP-carboluciferin (AMP=adenosine monophosphate) and AMP-firefly luciferin showed that the nature of the thiazoline mimicking moiety affected the adenylation step of the luciferin-luciferase reaction required for production of potent BL. In addition, BL of 6 in living mice differed from that of 1 in that its luminescence decay rate was slower. PMID:27220106

  16. Design and synthesis of novel arctigenin analogues for the amelioration of metabolic disorders.

    PubMed

    Duan, Shudong; Huang, Suling; Gong, Jian; Shen, Yu; Zeng, Limin; Feng, Ying; Ren, Wenming; Leng, Ying; Hu, Youhong

    2015-04-01

    Analogues of the natural product (-)-arctigenin, an activator of adenosine monophosphate activated protein kinase, were prepared in order to evaluate their effects on 2-deoxyglucose uptake in L6 myotubes and possible use in ameliorating metabolic disorders. Racemic arctigenin 2a was found to display a similar uptake enhancement as does (-)-arctigenin. As a result, the SAR study was conducted utilizing racemic compounds. The structure-activity relationship study led to the discovery of key substitution patterns on the lactone motif that govern 2-deoxyglucose uptake activities. The results show that replacement of the para-hydroxyl group of the C-2 benzyl moiety of arctigenin by Cl has a pronounced effect on uptake activity. Specifically, analogue 2p, which contains the p-Cl substituent, stimulates glucose uptake and fatty acid oxidation in L6 myotubes. PMID:25941553

  17. Current european regulatory perspectives on insulin analogues.

    PubMed

    Enzmann, Harald G; Weise, Martina

    2011-01-01

    Insulin analogues are increasingly considered as an alternative to human insulin in the therapy of diabetes mellitus. Insulin analogues (IAs) are chemically different from human insulin and may have different pharmacokinetic or pharmacodynamic properties. The significance of the modifications of the insulin molecule for the safety profile of IAs must be considered. This review describes the regulatory procedure and the expectations for the scientific content of European marketing authorization applications for innovative IAs submitted to the European Medicines Agency. Particular consideration is given to a potential cancer hazard. Specific regulatory guidance on how to address a possible carcinogenic or tumor promoting effect of innovative IAs in non-clinical studies is available. After marketing authorization, the factual access of patients to the new product will be determined to great extent by health technology assessment bodies, reimbursement decisions and the price. Whereas the marketing authorization is a European decision, pricing and reimbursement are national or regional responsibilities. The assessment of benefit and risk by the European Medicines Agency is expected to influence future decisions on price and reimbursement on a national or regional level. Collaborations between regulatory agencies and health technology assessment bodies have been initiated on European and national level to facilitate the use of the European Medicines Agency's benefit risk assessment as basis on which to build the subsequent health technology assessment. The option for combined or joint scientific advice procedures with regulators and health technology assessment bodies on European level or on a national level in several European Member States may help applicants to optimize their development program and dossier preparation in regard of both European marketing authorization application and reimbursement decisions. PMID:21736748

  18. Terrestrial Analogues for Lunar Impact Melt Flows

    NASA Technical Reports Server (NTRS)

    Neish, C. D.; Hamilton, C. W.; Hughes, S. S.; Nawotniak, S. Kobs; Garry, W. B.; Skok, J. R.; Elphic, R. C.; Schaefer, E.; Carter, L. M.; Bandfield, J. L.; Osinski, G. R.; Lim, D.; Heldmann, J. L.

    2016-01-01

    Lunar impact melt deposits have unique physical properties. They have among the highest observed radar returns at S-Band (12.6 cm wavelength), implying that they are rough at the decimeter scale. However, they are also observed in high-resolution optical imagery to be quite smooth at the meter scale. These characteristics distinguish them from well-studied terrestrial analogues, such as Hawaiian pahoehoe and ?a ?a lava flows. The morphology of impact melt deposits can be related to their emplacement conditions, so understanding the origin of these unique surface properties will help to inform us as to the circumstances under which they were formed. In this work, we seek to find a terrestrial analogue for well-preserved lunar impact melt flows by examining fresh lava flows on Earth. We compare the radar return and high-resolution topographic variations of impact melt flows to terrestrial lava flows with a range of surface textures. The lava flows examined in this work range from smooth Hawaiian pahoehoe to transitional basaltic flows at Craters of the Moon (COTM) National Monument and Preserve in Idaho to rubbly and spiny pahoehoe-like flows at the recent eruption at Holuhraun in Iceland. The physical properties of lunar impact melt flows appear to differ from those of all the terrestrial lava flows studied in this work. This may be due to (a) differences in post-emplacement modification processes or (b) fundamental differences in the surface texture of the melt flows due to the melts' unique emplacement and/or cooling environment. Information about the surface properties of lunar impact melt deposits will be critical for future landed missions that wish to sample these materials.

  19. Geochemical Fate and Transport of Diphenhydramine and Cetirizine in Soil

    NASA Astrophysics Data System (ADS)

    Wireman, R.; Rutherford, C. J.; Vulava, V. M.; Cory, W. C.

    2015-12-01

    Pharmaceuticals compounds presence in natural soils and water around the world has become a growing concern. These compounds are being discharged into the environment through treated wastewater or municipal sludge applications. The main goal of this study is determine their geochemical fate in natural soils. In this study we investigated sorption and transport behavior of diphenhydramine (DPH) and cetirizine (CTZ) in natural soils. These two commonly-used antihistamines are complex aromatic hydrocarbons with polar functional groups. Two clean acidic soils (pH~4.5) were used for these studies - an A-horizon soil that had higher organic matter content (OM, 7.6%) and a B-horizon soil that had lower OM (1.6%), but higher clay content (5.1%). Sorption isotherms were measured using batch reactor experiments. Data indicated that sorption was nonlinear and that it was stronger in clay-rich soils. The pKa's of DPH and CTZ are 8.98 and 8.27 respectively, i.e., these compounds are predominantly in cationic form at soil pH. In these forms, they preferentially sorb to negatively charged mineral surfaces (e.g., clay) present in the soils. Soil clay mineral characterization indicated that kaolinite was the dominant clay mineral present along with small amount of montmorillonite. The nonlinear sorption isotherms were fitted with Freundlich model. Transport behavior of both compounds was measured using glass chromatography columns. As expected both DPH and CTZ were strongly retained in the clay-rich soil as compared with OM-rich soil. The asymmetrical shape of the breakthrough curves indicated that there were likely two separate sorption sites in the soil, each with different reaction rates with each compound. A two-region advection-dispersion transport code was used to model the transport breakthrough curves. There was no evidence of transformation or degradation of the compounds during our sorption and transport studies.

  20. Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada

    USGS Publications Warehouse

    Simmons, Ardyth M.; Stuckless, John S.; with a Foreword by Abraham Van Luik, U.S. Department of Energy

    2010-01-01

    Natural analogues are defined for this report as naturally occurring or anthropogenic systems in which processes similar to those expected to occur in a nuclear waste repository are thought to have taken place over time periods of decades to millennia and on spatial scales as much as tens of kilometers. Analogues provide an important temporal and spatial dimension that cannot be tested by laboratory or field-scale experiments. Analogues provide one of the multiple lines of evidence intended to increase confidence in the safe geologic disposal of high-level radioactive waste. Although the work in this report was completed specifically for Yucca Mountain, Nevada, as the proposed geologic repository for high-level radioactive waste under the U.S. Nuclear Waste Policy Act, the applicability of the science, analyses, and interpretations is not limited to a specific site. Natural and anthropogenic analogues have provided and can continue to provide value in understanding features and processes of importance across a wide variety of topics in addressing the challenges of geologic isolation of radioactive waste and also as a contribution to scientific investigations unrelated to waste disposal. Isolation of radioactive waste at a mined geologic repository would be through a combination of natural features and engineered barriers. In this report we examine analogues to many of the various components of the Yucca Mountain system, including the preservation of materials in unsaturated environments, flow of water through unsaturated volcanic tuff, seepage into repository drifts, repository drift stability, stability and alteration of waste forms and components of the engineered barrier system, and transport of radionuclides through unsaturated and saturated rock zones.

  1. Uranium transport around the reactor zone at Bangombé and Okélobondo (Oklo): examples of hydrogeological and geochemical model integration and data evaluation

    NASA Astrophysics Data System (ADS)

    Gurban, I.; Laaksoharju, M.; Madé, B.; Ledoux, E.

    2003-03-01

    The sites at Bangombé and Okélobondo (Oklo) in Gabon provide a unique opportunity to study the behaviour of products from natural nuclear reactions in the vicinity of reactor zones which were active around two billion years ago. The Commission of the European Communities initiated the Oklo Natural Analogue Programme. One of the principal aims was to study indications of present time migration of elements from the reactor zones under ambient conditions. The hydrogeological and hydrochemical data from the Oklo sites were modelled in order to better understand the geochemical behaviour of radionuclides in the natural system, by using independent models and by comparing the modelling outcome. Two modelling approaches were used: M3 code (hydrochemical mixing and mass balance model), developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) and HYTEC (reactive transport model) developed by Ecole des Mines de Paris. Two different reactor zones were studied: Bangombé, a shallow site, the reactor being at 11 m depth, and OK84 at Okélobondo, situated at about 450 m depth, more comparable with a real repository location. This allowed the validation of modelling tools in two different sedimentary environments: one shallow, with a more homogeneous layering situated in an area of meteoric alteration, and the other offering the opportunity to study radionuclide migration from the reaction zone over a distance of 450 m through very heterogeneous sedimentary layers. The modeling results indicate that the chemical reactions retarding radionuclide transport are very different at the two sites. At Bangombé, the decomposition of organic material consumes oxygen and at Okélobondo the oxygen is consumed by inorganic reactions resulting, in both cases, in uranium retardation. Both modelling approaches (statistic with M3 code and deterministic with HYTEC code) could describe this situation. The goal of this exercise is to test codes which can help to describe and

  2. Uranium transport around the reactor zone at Bangombé and Okélobondo (Oklo): examples of hydrogeological and geochemical model integration and data evaluation.

    PubMed

    Gurban, I; Laaksoharju, M; Madé, B; Ledoux, E

    2003-03-01

    The sites at Bangombé and Okélobondo (Oklo) in Gabon provide a unique opportunity to study the behaviour of products from natural nuclear reactions in the vicinity of reactor zones which were active around two billion years ago. The Commission of the European Communities initiated the Oklo Natural Analogue Programme. One of the principal aims was to study indications of present time migration of elements from the reactor zones under ambient conditions. The hydrogeological and hydrochemical data from the Oklo sites were modelled in order to better understand the geochemical behaviour of radionuclides in the natural system, by using independent models and by comparing the modelling outcome. Two modelling approaches were used: M3 code (hydrochemical mixing and mass balance model), developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) and HYTEC (reactive transport model) developed by Ecole des Mines de Paris. Two different reactor zones were studied: Bangombé, a shallow site, the reactor being at 11 m depth, and OK84 at Okélobondo, situated at about 450 m depth, more comparable with a real repository location. This allowed the validation of modelling tools in two different sedimentary environments: one shallow, with a more homogeneous layering situated in an area of meteoric alteration, and the other offering the opportunity to study radionuclide migration from the reaction zone over a distance of 450 m through very heterogeneous sedimentary layers. The modeling results indicate that the chemical reactions retarding radionuclide transport are very different at the two sites. At Bangombé, the decomposition of organic material consumes oxygen and at Okélobondo the oxygen is consumed by inorganic reactions resulting, in both cases, in uranium retardation. Both modelling approaches (statistic with M3 code and deterministic with HYTEC code) could describe this situation. The goal of this exercise is to test codes which can help to describe and

  3. Geochemical and isotopic characterization of groundwater origins in a Mediterranean karst system (southern France)

    NASA Astrophysics Data System (ADS)

    Seidel, J. L.; Ladouche, B.; Batiot-Guilhe, C.

    2013-12-01

    Geochemical and isotopic ratio (11B/10B and 87Sr/86Sr) results are reported for better determining the groundwater origins in the Lez Karst system (southern France). The Lez spring is the main perennial outlet of the system and supplies with drinking water the metropolitan area of Montpellier. According to the hydrodynamic conditions, five water-types discharge at the Lez spring with important mineralization fluctuations (Caetano Bicalho et al., 2012). This geochemical response suggests that hydrodynamics targets groundwater circulation, resulting from different water end-member solicitation and mixing. Previous studies using conventional natural tracers do not succeed to identify all the water compartments supporting the flow during the hydrologic cycle (Marjolet & Salado, 1977; Joseph et al., 1988) and to explain the mineralization variation of the Lez spring. The present study combines a basic geochemical survey data with boron and strontium isotope ratio data for a better characterization of the Lez spring geochemical functioning. Groundwater samples were collected at the Lez spring and surrounding springs and wells under different hydrologic conditions from 2009 to 2011. Major, trace and rare earth elements were determined at AETE analytical platform (OREME, Univ. Montpellier 2) by ionic chromatography and Q-ICP-MS respectively. d11B and 87Sr/86Sr were determined at BRGM/MMA Orleans by TIMS. The geochemical survey has been extended at a larger scale by sampling the main geochemical end- members already identified to replace the Lez spring waters in the regional geochemical context. From this geochemical study, valuable informations have been provided on the reservoir types and water origins flowing in high and low stage periods. For the highly mineralized waters occurring in the fall first rainy events or severe low stages, a deep contribution is highlighted but B and Sr isotopic data do not ascertain the two Triassic end-members (halite or gypsum) as possible

  4. Geochemistry of a continental site of serpentinization, the Tablelands Ophiolite, Gros Morne National Park: A Mars analogue

    NASA Astrophysics Data System (ADS)

    Szponar, Natalie; Brazelton, William J.; Schrenk, Matthew O.; Bower, Dina M.; Steele, Andrew; Morrill, Penny L.

    2013-06-01

    The presence of aqueously altered, olivine-rich rocks along with carbonate on Mars suggest that serpentinization may have occurred in the past and may be occurring presently in the subsurface, and possibly contributing methane (CH4) to the martian atmosphere. Serpentinization, the hydration of olivine in ultramafic rocks, yields ultra-basic fluids (pH ⩾ 10) with unique chemistry (i.e. Ca2+-OH- waters) and hydrogen gas, which can support abiogenic production of hydrocarbons (i.e. Fischer-Tropsch Type synthesis) and subsurface chemosynthetic metabolisms. Mars analogue sites of present-day serpentinization can be used to determine what geochemical measurements are required for determining the source methane at sites of serpentinization on Earth and possibly on Mars. The Tablelands Ophiolite is a continental site of present-day serpentinization and a Mars analogue due to the presence of altered olivine-rich ultramafic rocks with both carbonate and serpentine signatures. This study describes the geochemical indicators of present-day serpentinization as evidenced by meteoric ultra-basic reducing groundwater discharging from ultramafic rocks, and travertine and calcium carbonate sediment, which form at the discharge points of the springs. Dissolved hydrogen concentrations (0.06-1.20 mg/L) and methane (0.04-0.30 mg/L) with δ13CCH4 values (-28.5‰ to -15.6‰) were measured in the spring fluids. Molecular and isotopic analyses of CH4, ethane, propane, butane, pentane and hexane suggest a non-microbial source of methane, and attribute the origin of methane and higher hydrocarbon gases to either thermogenic or abiogenic pathways.

  5. Reservoir simulation and geochemical study of Cerro Prieto I wells

    SciTech Connect

    Lippmann, M.J. ); Truesdell, A.H. )

    1990-03-01

    Combined reservoir simulation and geochemical data analysis are used to investigate the effects of recharge and other reservoir processes occurring in the western part of the Cerro Prieto, Mexico, geothermal field (i.e., Cerro Prieto I area). Enthalpy-based temperatures and bottomhole temperatures are calculated based on simplified models of the system, considering different reservoir boundary conditions and zones of contrasting initial temperatures and reservoir properties. By matching the computed trends with geothermometer-based temperature and enthalpy histories of producing wells, the main processes active in the western area of Cerro Prieto are identified. This part of the geothermal system is strongly influenced by nearby groundwater aquifers; cooler waters readily recharge the reservoirs. In response to exploitation, the natural influx of cold water into the shallower alpha reservoir is mainly from the west and down Fault L, while the recharge to the deeper beta reservoir in this part of the field, seems to be only lateral, from the west and possibly south. 11 refs., 12 figs.

  6. New geochemical investigations in Platanares and Azacualpa geothermal sites (Honduras)

    NASA Astrophysics Data System (ADS)

    Barberi, Franco; Carapezza, Maria Luisa; Cioni, Roberto; Lelli, Matteo; Menichini, Matia; Ranaldi, Massimo; Ricci, Tullio; Tarchini, Luca

    2013-05-01

    Platanares and Azacualpa geothermal sites of Honduras are located in an inner part of the Caribbean Plate far from the active volcanic front of Central America. Here geology indicates that there are not the conditions for the occurrence of shallow magmatic heat sources for high-enthalpy geothermal resources. Geothermal perspectives are related to the possibility of a deep circulation of meteoric water along faults and the storage of the heated fluid in fractured permeable reservoirs. Geochemical geothermometers indicate a temperature for the deeper part of the geothermal reservoir close to 200 °C for Platanares and of 150-170 °C for Azacualpa. Calcite scaling, with subordinate silica deposition has to be expected in both sites. CO2 soil flux investigations have been carried out in both areas and reveal the presence of positive anomalies likely corresponding to the presence at depth of fractured degassing geothermal reservoirs. Compared with the geothermal areas of Central Italy whose reservoirs are hosted in carbonate rocks, e.g. Latera (Chiodini et al., 2007), the CO2 soil flux measured in Honduras is significantly lower (mean of 17 g/m2day at Platanares and of 163 g/m2day at Azacualpa) probably because of the dominant silicate nature of the deep reservoirs.

  7. A model of isotope fractionation in reacting geochemical systems

    SciTech Connect

    Lee, Ming-Kuo; Bethke, C.M.

    1996-11-01

    The authors present a numerical technique that predicts how the stable isotopes {sup 2}H, {sup 13}C, {sup 18}O, and {sup 34}S fractionate among solvent, aqueous species, minerals, and gases over the course of a geochemical reaction process. This model is based on mass balance techniques similar to those already presented in the literature but differs from previous techniques in that it allows minerals to be segregated form isotopic exchange instead of remaining in isotopic equilibrium. Such an approach allows us to simulate the fractionation of isotopes between rock and fluid resulting solely from mineral dissolution and precipitation. The technique was tested by modeling isotopic fractionation during several reaction processes, including (1) dolomitization of limestone by a migrating pore fluid, (2) diagenetic alteration of the Permian Lyons sandstone in the Denver basin, and (3) hydrothermal alteration of the Okanagan Batholith in southern British Columbia. The results of calculations in which minerals are segregated from isotopic exchange compare well to isotopic trends observed in nature but differ markedly from calculations that assume isotopic equilibrium. 54 refs., 4 figs., 3 tabs.

  8. Modeling Background Radiation in our Environment Using Geochemical Data

    SciTech Connect

    Malchow, Russell L.; Marsac, Kara; Burnley, Pamela; Hausrath, Elisabeth; Haber, Daniel; Adcock, Christopher

    2015-02-01

    Radiation occurs naturally in bedrock and soil. Gamma rays are released from the decay of the radioactive isotopes K, U, and Th. Gamma rays observed at the surface come from the first 30 cm of rock and soil. The energy of gamma rays is specific to each isotope, allowing identification. For this research, data was collected from national databases, private companies, scientific literature, and field work. Data points were then evaluated for self-consistency. A model was created by converting concentrations of U, K, and Th for each rock and soil unit into a ground exposure rate using the following equation: D=1.32 K+ 0.548 U+ 0.272 Th. The first objective of this research was to compare the original Aerial Measurement System gamma ray survey to results produced by the model. The second objective was to improve the method and learn the constraints of the model. Future work will include sample data analysis from field work with a goal of improving the geochemical model.

  9. Models of geochemical systems from mixture theory: diffusion

    SciTech Connect

    Kirwan, A.D. Jr; Kump, L.R.

    1987-05-01

    The problem of diffusion of a geochemical component in a natural environment is investigated from the standpoint of mixture theory. The approach here differs from previous diffusion studies in that both the conservation of mass and momentum for the component is considered. This approach avoids parameterizing the diffusive flux in the mass equation by Fick's law. It is shown that when the momentum equation is included with the mass equation, the linear approximation for the space-time distribution of a solute in a binary system is the telegraph equation, well known from electrodynamics. This contrasts with the diffusion equation, which relies on introducing the Fick's law assumption into the conservation of mass equation for the solute. Solutions for both the diffusion and telegraph equation models are obtained and compared for the case of migration of a minor component into the sea bed when the sediment-water interface concentration is a prescribed function of time. Although the stationary, steady state solutions of the telegraph and diffusion equations are identical, the former has a transient solution in which fluctuations propagate at finite speed. The Fickian assumption, in contrast, requires an infinite speed of propagation.

  10. Coupled hydrological and geochemical process evolution at the Landscape Evolution Observatory

    NASA Astrophysics Data System (ADS)

    Troch, P. A. A.

    2015-12-01

    Predictions of hydrologic and biogeochemical responses to natural and anthropogenic forcing at the landscape scale are highly uncertain due to the effects of heterogeneity on the scaling of reaction, flow and transport phenomena. The physical, chemical and biological structures and processes controlling reaction, flow and transport in natural landscapes interact at multiple space and time scales and are difficult to quantify. The current paradigm of hydrological and geochemical theory is that process descriptions derived from observations at small scales in controlled systems can be applied to predict system response at much larger scales, as long as some 'equivalent' or 'effective' values of the scale-dependent parameters can be identified. Furthermore, natural systems evolve in time in a way that is hard to observe in short-run laboratory experiments or in natural landscapes with unknown initial conditions and time-variant forcing. The spatial structure of flow pathways along hillslopes determines the rate, extent and distribution of geochemical reactions (and biological colonization) that drive weathering, the transport and precipitation of solutes and sediments, and the further evolution of soil structure. The resulting evolution of structures and processes, in turn, produces spatiotemporal variability of hydrological states and flow pathways. There is thus a need for experimental research to improve our understanding of hydrology-biogeochemistry interactions and feedbacks at appropriate spatial scales larger than laboratory soil column experiments. Such research is complicated in real-world settings because of poorly constrained impacts of initial conditions, climate variability, ecosystems dynamics, and geomorphic evolution. The Landscape Evolution Observatory (LEO) at Biosphere 2 offers a unique research facility that allows real-time observations of incipient hydrologic and biogeochemical response under well-constrained initial conditions and climate

  11. The Geochemical Figure Print of an Early Paleozoic OAE

    NASA Astrophysics Data System (ADS)

    Gill, B.; Young, S.; Kump, L.; Saltzman, M.; Lyons, T.

    2007-12-01

    The Paleozoic Era contains many large, commonly globally expressed positive carbon isotope excursions recorded in carbonate rocks. In younger Mesozoic rocks, similar excursions are often easily linked to organic-rich deposits formed from enhanced carbon burial under ocean-scale anoxia -i.e., oceanic anoxic events (OAEs). These events are important since voluminous organic carbon and pyrite burial in anoxic settings can be a central player in modulating the amount of oxygen and carbon dioxide in the atmosphere, and many of Earth's major extinctions are coeval with ocean-scale anoxia. In contrast, physical records of organic carbon burial tied to the carbon isotope record are scarce in the Paleozoic; leading to ambiguity in the interpretation of the isotope data. These data become less cryptic when viewed in light of coeval seawater sulfur isotope trends. For the globally expressed, Late Cambrian (SPICE) carbon isotope excursion, carbonate-C and sulfate-S records reveal parallel, positive isotope shifts suggesting enhanced organic C and pyrite S burial. Additionally, both organic carbon and pyrite sulfur isotope data from the Alum Shale of Sweden record the SPICE Event, putting to rest questions of the primary nature of the carbonate records. Comparison of the SPICE to similar isotope data from the Toarcian OAE and results from geochemical box modeling of both events lead us to conclude that the SPICE Event is a prime candidate for an early Paleozoic OAE. Additional evidence for increased ocean anoxia coincident with the SPICE also comes from the Alum Shale. Molybdenum concentrations show muted enrichment during the extent of the SPICE, despite data that show the basin was persistently euxinic before, during and after the event. Significant increases in molybdenum concentration occur only immediately after the event; suggesting a depleted seawater Mo inventory associated with a greatly expanded global anoxic Mo sink during the SPICE. An interesting result from

  12. Geochemical Evidence of Cryptic Sulfur Cycling in Salt Marsh Sediments

    NASA Astrophysics Data System (ADS)

    Mills, J. V.; Antler, G.; Turchyn, A. V.

    2014-12-01

    In modern marine and marginal marine sediments, bacterial sulfate reduction dominates the subsurface oxidation of organic carbon due to the abundance of sulfate in many surface environments. While bacterial sulfate reduction may control anaerobic organic carbon oxidation, there is increasing evidence that iron redox chemistry may be intimately linked to sulfur redox chemistry in the anoxic subsurface, with iron species acting as catalysts or electron shuttles for the microbial use of sulfur, and vice versa. We use stable isotope and geochemical techniques to explore the coupling of the iron and sulfur cycles in salt marsh sediments in North Norfolk, UK. Unique among previously studied environments, these sediments contain high concentrations of both sulfate (20-40mM) and ferrous iron (1-3mM). High ferrous iron concentrations require extended regions of bacterial iron reduction. Within these zones of iron reduction we would predict no sulfate reduction, and lack of change in sulfur isotopes and no loss of sulfate suggest that there is no net sulfate reduction in this zone. However, coincident with the increase in ferrous iron concentrations, the δ18Osulfate exhibits significant increases of up to 5‰. The decoupling of the sulfur and oxygen isotopes of sulfate is suggestive of a cryptic sulfur cycle in which sulfate is reduced to an intermediate valence state sulfur species and subsequently reoxidized to sulfate; this cycle must by quasi-quantitative to produce the suite of geochemical observations. We further explore the nature of this cycling through a series of batch reactor incubation experiments. When sediments are incubated in 18O-enriched water, significant shifts (>15‰) in the δ18Osulfate are observed with no corresponding shift in sulfur isotopes. This provides direct evidence that microbial assemblages in these salt marsh sediments facilitate a cryptic cycling of sulfur, potentially mediated by iron species in the zone of iron reduction. We contrast

  13. DNA information: from digital code to analogue structure.

    PubMed

    Travers, A A; Muskhelishvili, G; Thompson, J M T

    2012-06-28

    The digital linear coding carried by the base pairs in the DNA double helix is now known to have an important component that acts by altering, along its length, the natural shape and stiffness of the molecule. In this way, one region of DNA is structurally distinguished from another, constituting an additional form of encoded information manifest in three-dimensional space. These shape and stiffness variations help in guiding and facilitating the DNA during its three-dimensional spatial interactions. Such interactions with itself allow communication between genes and enhanced wrapping and histone-octamer binding within the nucleosome core particle. Meanwhile, interactions with proteins can have a reduced entropic binding penalty owing to advantageous sequence-dependent bending anisotropy. Sequence periodicity within the DNA, giving a corresponding structural periodicity of shape and stiffness, also influences the supercoiling of the molecule, which, in turn, plays an important facilitating role. In effect, the super-helical density acts as an analogue regulatory mode in contrast to the more commonly acknowledged purely digital mode. Many of these ideas are still poorly understood, and represent a fundamental and outstanding biological question. This review gives an overview of very recent developments, and hopefully identifies promising future lines of enquiry. PMID:22615471

  14. Rhodomycin analogues from Streptomyces purpurascens: isolation, characterization and biological activities.

    PubMed

    Holkar, Sunita; Begde, Deovrat; Nashikkar, Nandita; Kadam, Tukaram; Upadhyay, Avinash

    2013-12-01

    During a screening program for bioactive natural products, a potential Streptomyces sp was isolated from soil. On the basis of biochemical, cultural, physiological and 16S rRNA gene analysis, it was identified as Streptomyces purpurascens. The isolate was grown in liquid medium and the crude antibiotic complex was obtained by ethyl acetate extraction. Seven purified fractions were obtained by preparative Thin Layer Chromatography (TLC). Acid hydrolysis of each fraction and subsequent TLC led to the identification of aglycones and sugars indicating these compounds to be Rhodomycin and its analogues. The identity of these compounds was established on the basis of UV-visible and FT-IR spectra and comparison with published data. The compounds were active against Gram-positive bacteria. Compound E, identified as Rhodomycin B, was found to be the most potent compound with an MIC of 2 μg/ml against Bacillus subtilis. Compounds A and F identified as α2-Rhodomycin II and Obelmycin respectively, and Compound E exhibited an IC50 of 8.8 μg/ml against HeLa cell line but no cytotoxicity was found against L929.

  15. An analogue experimental model of depth fluctuations in lava lakes

    NASA Astrophysics Data System (ADS)

    Witham, Fred; Woods, Andrew W.; Gladstone, Charlotte

    2006-07-01

    Lava lakes, consisting of molten degassing lava in summit craters of active basaltic volcanoes, sometimes exhibit complex cycles of filling and emptying on time-scales of hours to weeks such as recorded at Pu’u’O’o in Hawaii and Oldoinyo Lengai in Tanzania. Here we report on a new series of analogue laboratory experiments of two-phase flow in a reservoir-conduit-lava lake system which spontaneously generates oscillations in the depth of liquid within the lake. During the recharge phase, gas supplied from a subsurface reservoir of degassing magma drives liquid magma up the conduit, causing the lake to fill. As the magmastatic pressure in the lake increases, the upward supply of magma, driven by the gas bubbles, falls. Eventually the upflow becomes unstable, and liquid drains downwards from the lake, driven by the magmastatic pressure of the overlying lake, suppressing the ascent of any more bubbles from the chamber. At a later stage, once the lake has drained sufficiently, the descent speed of liquid through the conduit decreases below the ascent speed of the bubbles, and the recharge cycle resumes. Application of a quantitative model of the experiments to the natural system is broadly consistent with field data.

  16. Bioactivity of permselective PVA hydrogels with mixed ECM analogues.

    PubMed

    Nafea, Eman H; Poole-Warren, Laura A; Martens, Penny J

    2015-12-01

    The presentation of multiple biological cues, which simulate the natural in vivo cell environment within artificial implants, has recently been identified as crucial for achieving complex cellular functions. The incorporation of two or more biological cues within a largely synthetic network can provide a simplified model of multifunctional ECM presentation to encapsulated cells. Therefore, the aim of this study was to examine the effects of simultaneously and covalently incorporating two dissimilar biological molecules, heparin and gelatin, within a PVA hydrogel. PVA was functionalized with 7 and 20 methacrylate functional groups per chain (FG/c) to tailor the permselectivity of UV photopolymerized hydrogels. Both heparin and gelatin were covalently incorporated into PVA at an equal ratio resulting in a final PVA:heparin:gelatin composition of 19:0.5:0.5. The combination of both heparin and gelatin within a PVA network has proven to be stable over time without compromising the PVA base characteristics including its permselectivity to different proteins. Most importantly, this combination of ECM analogues supplemented PVA with the dual functionalities of promoting cellular adhesion and sequestering growth factors essential for cellular proliferation. Multi-functional PVA hydrogels with synthetically controlled network characteristics and permselectivity show potential in various biomedical applications including artificial cell implants.

  17. Bead-Based Microfluidic Sediment Analogues: Fabrication and Colloid Transport.

    PubMed

    Guo, Yang; Huang, Jingwei; Xiao, Feng; Yin, Xiaolong; Chun, Jaehun; Um, Wooyong; Neeves, Keith B; Wu, Ning

    2016-09-13

    Mobile colloids can act as carriers for low-solubility contaminants in the environment. However, the dominant mechanism for this colloid-facilitated transport of chemicals is unclear. Therefore, we developed a bead-based microfluidic platform of sediment analogues and measured both single and population transport of model colloids. The porous medium is assembled through a bead-by-bead injection method. This approach has the versatility to build both electrostatically homogeneous and heterogeneous media at the pore scale. A T-junction at the exit also allowed for encapsulation and enumeration of colloids effluent at single particle resolution to give population dynamics. Tortuosity calculated from pore-scale trajectory analysis and its comparison with lattice Boltzmann simulations revealed that transport of colloids was influenced by the size exclusion effect. The porous media packed by positively and negatively charged beads into two layers showed distinctive colloidal particle retention and significant remobilization and re-adsorption of particles during water flushing. We demonstrated the potential of our method to fabricate porous media with surface heterogeneities at the pore scale. With both single and population dynamics measurement, our platform has the potential to connect pore-scale and macroscale colloid transport on a lab scale and to quantify the impact of grain surface heterogeneities that are natural in the subsurface environment. PMID:27548505

  18. Synthesis and biological evaluations of a series of thaxtomin analogues.

    PubMed

    Zhang, Hongbo; Wang, Qingpeng; Ning, Xin; Hang, Hang; Ma, Jing; Yang, Xiande; Lu, Xiaolin; Zhang, Jiabao; Li, Yonghong; Niu, Congwei; Song, Haoran; Wang, Xin; Wang, Peng George

    2015-04-15

    Thaxtomins are a unique family of phytotoxins with unique 4-nitroindole and diketopiperazine fragments possessing potential herbicidal activities. This work presents the total synthesis of natural product thaxtomin C and its analogues. The extensive structure-activity relationship study screens four effective compounds, including thaxtomin A and thaxtomin C. It is indicated that 4-nitro indole fragment is essential for phytotoxicity, while benzyl and m-hydroxybenzyl substituents on the diketopiperazine ring are favorable for the efficacy. The N-methylations on indole and diketopiperazine show weak influence on the herbicidal activities. The four selected compounds show effective herbicidal activities against Brassica campestris, Amaranthus retroflexus, and Abutilon theophrasti, which are comparable or better than dichlobenil, even at a dosage of 187.5 g ha(-1). Moreover, these four compounds show good crop-selective properties to different crops and exhibit moderate protoporphyrinogen oxidase (PPO) enzyme inhibition. The antifungal results indicate that thaxtomin C displays inhibition to a wide range of fungi. PMID:25804187

  19. Geochemical evidence for invasion of Kilauea's plumbing system by Mauna Loa magma

    USGS Publications Warehouse

    Rhodes, J.M.; Wenz, K.P.; Neal, C.A.; Sparks, J.W.; Lockwood, J.P.

    1989-01-01

    From the beginning of the study of Hawaiian volcanism there has been controversy over possible relationships between the neighbouring active volcanoes Mauna Loa and Kilauea1-5. Seismic activity, thought to reflect upward migration of magma, reveals that the magmatic plumbing systems apparently converge at depth to form a broad funnel within the mantle6. Although on rare occasions they have erupted concurrently, the brief historical eruptive record appears to show that when Kilauea is most active, Mauna Loa is in repose and vice versa, suggesting that they may be competing for the same magma supply5,7. Petrological, geochemical and isotope data, however, require a diametrically opposite conclusion. Distinct differences in major-element, trace-element and isotope compositions of lavas are regarded as compelling evidence that the two volcanoes have separate magmatic plumbing systems, supplied by parental magmas from physically and geochemically distinct mantle sources8-13. Here we present preliminary geochemical data which show that in the past 2,000 years Kilauea has erupted a spectrum of lava compositions resembling historical Kilauea lavas at one end and Mauna Loa lavas at the other. We discuss the cause of this diversity, and speculate that magma from Mauna Loa may have invaded Kilauea's 'high-level' magmatic plumbing system. ?? 1989 Nature Publishing Group.

  20. In Situ Rates of Sulfate Reduction in Response to Geochemical Perturbations

    USGS Publications Warehouse

    Kneeshaw, T.A.; McGuire, J.T.; Cozzarelli, I.M.; Smith, E.W.

    2011-01-01

    Rates of in situ microbial sulfate reduction in response to geochemical perturbations were determined using Native Organism Geochemical Experimentation Enclosures (NOGEEs), a new in situ technique developed to facilitate evaluation of controls on microbial reaction rates. NOGEEs function by first trapping a native microbial community in situ and then subjecting it to geochemical perturbations through the introduction of various test solutions. On three occasions, NOGEEs were used at the Norman Landfill research site in Norman, Oklahoma, to evaluate sulfate-reduction rates in wetland sediments impacted by landfill leachate. The initial experiment, in May 2007, consisted of five introductions of a sulfate test solution over 11 d. Each test stimulated sulfate reduction with rates increasing until an apparent maximum was achieved. Two subsequent experiments, conducted in October 2007 and February 2008, evaluated the effects of concentration on sulfate-reduction rates. Results from these experiments showed that faster sulfate-reduction rates were associated with increased sulfate concentrations. Understanding variability in sulfate-reduction rates in response to perturbations may be an important factor in predicting rates of natural attenuation and bioremediation of contaminants in systems not at biogeochemical equilibrium. Copyright ?? 2011 The Author(s). Journal compilation ?? 2011 National Ground Water Association.

  1. Modelling the closure-related geochemical evolution of groundwater at a former uranium mine.

    PubMed

    Bain, J G; Mayer, K U; Blowes, D W; Frind, E O; Molson, J W; Kahnt, R; Jenk, U

    2001-11-01

    A newly developed reactive transport model was used to evaluate the potential effects of mine closure on the geochemical evolution in the aquifer downgradient from a mine site. The simulations were conducted for the Königstein uranium mine located in Saxony, Germany. During decades of operation, uranium at the former mine site had been extracted by in situ acid leaching of the ore underground, while the mine was maintained in a dewatered condition. One option for decommissioning is to allow the groundwater level to rise to its natural level, flooding the mine workings. As a result, pore water containing high concentrations of dissolved metals, radionuclides, and sulfate may be released. Additional contamination may arise due to the dissolution of minerals contained in the aquifer downgradient of the mine. On the other hand, dissolved metals may be attenuated by reactions within the aquifer. The geochemical processes and interactions involved are highly non-linear and their impact on the quality of the groundwater and surface water downstream of the mine is not always intuitive. The multicomponent reactive transport model MIN3P, which can describe mineral dissolution-precipitation reactions, aqueous complexation, and oxidation-reduction reactions, is shown to be a powerful tool for investigating these processes. The predictive capabilities of the model are, however, limited by the availability of key geochemical parameters such as the presence and quantities of primary and secondary mineral phases. Under these conditions, the model can provide valuable insight by means of sensitivity analyses.

  2. Geochemical heterogeneities within the Crozet hotspot

    NASA Astrophysics Data System (ADS)

    Breton, Thomas; Nauret, François; Pichat, Sylvain; Moine, Bertrand; Moreira, Manuel; Rose-Koga, Estelle F.; Auclair, Delphine; Bosq, Chantal; Wavrant, Laurène-Marie

    2013-08-01

    The Crozet Plateau is a 54 Ma-old volcanic plateau that supports five islands characterized by recent volcanic manifestations that are the surface expression of a deep-mantle plume. Due to their remote location and difficult access, the Crozet Islands are poorly sampled. Both the petrological descriptions and geochemical data are scarce. Thus, the sources of the Crozet plume are still under debate. Similarly, the interactions between the Southwest Indian Ridge (SWIR) and the Crozet plume remain questioned. Here, we present a new set of isotopes (Pb, Sr, Nd and He), major and trace elements data on basalts from three islands of the Crozet Archipelago: Penguins, East, and Possession Islands. Our main purpose is to characterize the sources of the Crozet plume and to test its influence at regional scale. Two groups of lavas can be distinguished based on the isotopic data: East and Possession lavas, and Penguins lavas. Principal component analyses on our high-precision Pb isotopes data and literature data show that two mantle sources can explain most of the geochemical variability measured in Crozet lavas. A third minor contribution is however needed to fully explain the data. The entire set of isotopic compositions (Pb, Sr, Nd and He) can be explained by a mixing between three mantle sources: (1) a FOZO (Focus Zone) component, with 206Pb/204Pb higher than 19.5 and high 207Pb/204Pb, 208Pb/204Pb 87Sr/86Sr, 143Nd/144Nd and R/Ra (R/Ra=(He3/He4)sample/(He3/He4)atmosphere) ratios, that is mainly sampled Penguins lavas, (2) a component called “East-Possession” that is mostly sampled by the East-Possession lava group and which presents Pb, Sr and Nd isotope signatures similar to those of the Reunion-Mauritius Islands, and (3) a third minor contribution of the local Depleted MORB Mantle (DMM). The new He isotopes data on the Crozet plume allow us to propose that Crozet plume material is present in the segment of the Southwest Indian Ridge located between the Indomed (ITF

  3. Geochemical surveys in the Lusi mud eruption

    NASA Astrophysics Data System (ADS)

    Sciarra, Alessandra; Mazzini, Adriano; Etiope, Giuseppe; Inguaggiato, Salvatore; Hussein, Alwi; Hadi J., Soffian

    2016-04-01

    The Lusi mud eruption started in May 2006 following to a 6.3 M earthquake striking the Java Island. In the framework of the Lusi Lab project (ERC grant n° 308126) we carried out geochemical surveys in the Sidoarjo district (Eastern Java Island, Indonesia) to investigate the gas bearing properties of the Watukosek fault system that crosses the Lusi mud eruption area. Soil gas (222Rn, CO2, CH4) concentration and flux measurements were performed 1) along two detailed profiles (~ 1km long), trending almost W-E direction, and 2) inside the Lusi embankment (about 7 km2) built to contain the erupted mud. Higher gas concentrations and fluxes were detected at the intersection with the Watukosek fault and the antithetic fault system. These zones characterized by the association of higher soil gas values constitute preferential migration pathways for fluids towards surface. The fractures release mainly CO2 (with peaks up to 400 g/m2day) and display higher temperatures (up to 41°C). The main shear zones are populated by numerous seeps that expel mostly CH4. Flux measurements in the seeping pools reveal that φCO2 is an order of magnitude higher than that measured in the fractures, and two orders of magnitude higher for φCH4. An additional geochemical profile was completed perpendicularly to the Watukosek fault escarpement (W-E direction) at the foots of the Penanngungang volcano. Results reveal CO2 and CH4 flux values significantly lower than those measured in the embankment, however an increase of radon and flux measurements is observed approaching the foots of the escarpment. These measurements are complemented with a database of ~350 CH4 and CO2 flux measurements and some soil gas concentrations (He, H2, CO2, CH4 and C2H6) and their isotopic analyses (δ13C-CH4, δD-CH4 and δ13C-CO2). Results show that the whole area is characterized by diffused gas release through seeps, fractures, microfractures and soil degassing. The collected results shed light on the origin of the

  4. How to build stable geochemical reservoirs on Mars?

    NASA Astrophysics Data System (ADS)

    Plesa, Ana-Catalina; Tosi, Nicola; Breuer, Doris

    2014-05-01

    To explain the complex thermo-chemical processes needed for the formation of distinct and stable geochemical reservoirs early in the thermo-chemical evolution of Mars, most geochemical studies argue that fractional crystallization of a global magma ocean may reproduce the isotopic characteristic of the SNCs [1, 2]. However, geodynamical models show that such scenario is difficult to reconcile with other observations like late volcanic activity and crustal density values as obtained from gravity and topography modelling [3, 4]. The stable density gradient, which establishes after the mantle overturn has completed, inhibits thermal convection. Albeit capable to provide stable reservoirs, this scenario suggests a conductive mantle after the overturn which on the one hand fails to sample deep regions of the mantle and on the other hand is clearly at odds with the volcanic history of Mars. This is best explained by assuming a convective mantle and partial melting as the principal agents responsible for the generation and evolution of Martian volcanism. Therefore, in this work an alternative scenario for the formation of early stable geochemical</