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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 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

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. Macrolactam analogues of macrolide natural products.

    PubMed

    Hügel, Helmut M; Smith, Andrew T; Rizzacasa, Mark A

    2016-12-07

    The chemical modification of macrolide natural products into aza- or lactam analogues is a strategy employed to improve their metabolic stability and biological activity. The methods for the synthesis of several lactam analogues of macrolide natural products are highlighted and aspects of their biological properties presented.

  7. 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.

  8. 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.

  9. Naturalness in an emergent analogue spacetime.

    PubMed

    Liberati, Stefano; Visser, Matt; Weinfurtner, Silke

    2006-04-21

    Effective field theories (EFTs) have been widely used as a framework in order to place constraints on the Planck suppressed Lorentz violations predicted by various models of quantum gravity. There are, however, technical problems in the EFT framework when it comes to ensuring that small Lorentz violations remain small--this is the essence of the "naturalness" problem. Herein we present an "emergent" spacetime model, based on the "analogue gravity" program, by investigating a specific condensed-matter system. Specifically, we consider the class of two-component BECs subject to laser-induced transitions between the components, and we show that this model is an example for Lorentz invariance violation due to ultraviolet physics. Furthermore, our model explicitly avoids the naturalness problem, and makes specific suggestions regarding how to construct a physically reasonable quantum gravity phenomenology.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Using a Natural Analogue to Investigate Chemical Reactions Associated with Carbon Dioxide Sequestration

    NASA Astrophysics Data System (ADS)

    Navarre-Sitchler, A.; Kaszuba, J.; Thyne, G.

    2008-12-01

    Capture and storage of carbon dioxide in deep underground geologic formations (geologic carbon sequestration) is currently the most advanced technology for reducing or mitigating anthropogenic carbon dioxide emissions. There are a number of scientific challenges associated with injection and storage of large amounts of CO2 in geologic formations. Understanding the chemical reactions that can occur among reservoir rocks, aqueous fluids, and supercritical carbon dioxide ± other gasses is one of these challenges. Natural analogues to CO2 sequestration are systems where carbon dioxide has been stored over geologic time scales. By studying these analogues we can determine important chemical reactions between the host rock and stored gases. The Moxa Arch is a structural feature located in the southern end of the greater Green River Basin, Wyoming. Carbon dioxide and methane were emplaced in Paleozoic rocks, including the 1000 feet thick Mississippian age Madison Limestone, of the Moxa Arch through natural processes. Concentrations of carbon dioxide in the emplaced gas in these formations vary in the region of the Moxa Arch from 70-95% and are as low as ~ 15% in gas producing areas outside of the Moxa Arch. Methane, hydrogen sulfide and helium comprise the balance of the gas compositons. Geochemical reaction path and reactive transport models based upon the mineralogy of 12 core samples collected from three wells completed in the Madison Limestone near the Moxa Arch will be presented. These models help identify potential geochemical reactions between reservoir minerals and stored gasses.

  18. 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.

  19. 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

  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.

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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].

  6. 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.

  7. 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.

  8. 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

  9. Natural bacterial communities serve as quantitative geochemical biosensors

    DOE PAGES

    Smith, Mark B.; Rocha, Andrea M.; Smillie, Chris S.; ...

    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

  10. 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.

  11. Natural bacterial communities serve as quantitative geochemical biosensors.

    PubMed

    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. Copyright © 2015 Smith et al.

  12. Environmental Fate of Ge Analogues of Natural Imogolite

    NASA Astrophysics Data System (ADS)

    Masion, A.; Avellan, A.; Levard, C.; Achouak, W.; Santaella, C.; Rose, J.

    2016-12-01

    Imogolites are natural aluminosilicate nanotubes found in volcanic soils. They can be easily synthetized in the lab, but yields are poor. The Ge analogues of this material are obtained using a similar recipe, with the difference that yields are 2-3 orders of magnitude higher. These larger quantities raise the concern about the fate of these material in the environment once they reached their end of life. We examined the transformations and toxicity of a series of tubes differing in crystallinity and purity in a simulated rhizosphere environment. Tube integrity, and thus Ge release, is dependent on structural defects (vacancies) and impurities in the tube wall composition. However, the toxicity associated with these transformations is not correlated with the amount of released Ge but implies more complex homeostasis mechanisms.

  13. The Marqarin (Jordan) natural analogue for [sup 14] attenuation in cementitious barriers

    SciTech Connect

    Clark, I.D. . Ottawa-Carleton Geoscience Centre); Dayal, R. ); Khoury, H.N. . Dept. of Geology and Mineralogy)

    1994-01-01

    Carbonation reactions in Portland cement grout examined in the laboratory suggest high attenuation of [sup 14]C in cementitious barriers for low- and intermediate-level radioactive waste repositories. Natural cementitious environments at two sites, Maqarin and Daba, in Jordan offer evidence that extensive carbonation can occur at field scales under both unsaturated and saturated conditions. Here, in situ spontaneous combustion of bituminous marl in the past has led to calcination and formation of calcium/silica/alumina-oxides typical of Portland cement clinker. Retrograde alteration within these metamorphic zones began with hydration and precipitation of portlandite as a rock forming mineral along with ettringite, thaumasite, and other calcium-silica-hydrate-like phases. Metamorphism was a relatively recent event at the Maqarin site. Here hyperalkaline groundwater discharge from the alteration zones with two distinct geochemical facies: (a) higher TDS Ca-K-Na-OH-SO[sub 4] groundwaters (pH > 12.5) apparently represent the earliest discharge following hydration, and (b) lower TDS Ca-OH groundwaters (pH 12.0 to 12.4) which appear to be later-stage leachates from the alteration zone. Subsequent carbonation has precipitated secondary calcite observed in the Eastern alteration zone. In central Jordan, travertines associated with the Daba marble record a third phase of porewater discharge where silica has been remobilized during carbonation of CSH-like phases. The unique geochemical features of the Maqarin site were examined to evaluate the validity of using it as a potential natural analogue for cement grout carbonation reactions studied under laboratory conditions.

  14. Monitoring of Geoengineering Effects and their Natural and Anthropogenic Analogues

    NASA Astrophysics Data System (ADS)

    Duren, R. M.; Robock, A.; Stephens, G. L.; MacMynowski, D. G.

    2011-12-01

    A number of climate intervention concepts, referred to as "geoengineering," are being considered as an alternative approach to managing climate change. However, before we go down the path of deliberate climate intervention including precursor field-experiments, it is essential that we take the necessary steps to validate our understanding that underpins any of the proposed intervention concepts in order to understand all likely consequences and put in place the necessary strategies for monitoring the expected and unintended consequences of such intervention. The Keck Institute for Space Studies (KISS) is undertaking a project to identify specific priorities for improved scientific understanding and focused efforts to address selected priorities. The KISS project does not advocate the deployment of geoengineering or monitoring systems for potential field experiments but is rather a precautionary study with the following goals: 1) enumeration of where major gaps in our understanding exist in solar radiation management (SRM) approaches, 2) identification of the research that would be required to improve understanding of such impacts including modeling and observation of natural and anthropogenic analogues to geoengineering, and 3) a preliminary assessment of where gaps exist in observations of relevance to SRMs and what is needed to fill such gaps. This study focuses primarily on SRM rather than other proposed geoengineering techniques such as carbon dioxide removal from the atmosphere because there exist a number of analogues to the SRMs that currently operate on Earth that provide a unique opportunity to assess our understanding of the response of the climate system to associated changes in solar radiation. Additionally, the processes related to these analogues are also fundamental to understanding climate change itself being of central relevance to how climate is forced by aerosol and respond through clouds, among other influences (e.g., such research has potential

  15. Matsushiro Earthquake Swarm (1965-1967) as a Natural Analogue of CO2 Storage and Leakage

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Koide, H.; Tosha, T.; Todaka, N.; Nakanishi, S.; Aoyagi, R.; Benson, S.; Rutqvist, J.; Lewicki, J.

    2006-12-01

    The Matsushiro basin, Nagano city, Central Japan, is a unique natural analogue site of the CO2 storage and leakage through fault. From May 1966 to February 1967, ten million tons of CO2-bearing water discharged through surface ruptures and springs midst an earthquake swarm. The swarm began in August 1965 and the active period lasted two years followed by three-year relatively silent term. The location of water and CO2 discharge was concentrated in a narrow strip along the main focal fault. Weak seismic activities, CO2 bearing hot spa, and bubbles in rice paddy are observed, so the low intensity activities seem to continue. The fault is a left-lateral strike-slip fault striking NW-SE. Surface upheaval up to 90 cm and lateral motion corresponding to the strike-slip fault were observed. Based on this and additional geophysical evidence, some past studies adopted the idea that the upward water migration in the fault played a major role in the occurrence of the earthquake through the dilatancy mechanism. In this model, the earthquakes are assumed to follow the preceding hydrological and hydraulic phenomena such as water migration to the fractures in rock mass, reducing effective stress, and shear failures with increasing permeability. The authors anticipate that also CO2 played some vital roles in the phenomena observed at Matsushiro, and we could learn the CO2 behaviour in the underground condition. We assume that the fault and CO2 bearing water interacted through chemo-physical (precipitation/dissolution of carbonate and phase change) and mechanical (CO2 pressure induced stress and permeability change in the fault) processes, and affected the flow characters, seismicity, and the initiation and termination of the activities. For the investigation, geochemical surveys were carried out in the area to characterize present day surface CO2 flux. Geochemical and geomechanical modelling are being conducted for the quantitative understanding of the mechanisms. Also, water

  16. 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.

  17. Final report of the Peña Blanca natural analogue project

    SciTech Connect

    Levy, Schön S.; Goldstein, Steven Joel; Abdel-Fattah, Amr I.; Amato, Ronald S.; Anthony, Elizabeth; Cook, Paul; Dobson, Patrick F.; Fayek, Mostafa; French, Diana; Garza, Rodrigo de; Ghezzehei, Teamrat; Goodell, Philip C.; Harder, Steven H.; Ku, Teh-Lung; Luo, Shangde; Murrell, Michael Tildon; Norman, Deborah E.; Nunn, Andrew J.; Oliver, Ronald; Pekar-Carpenter, Katrina; Rearick, Michael Sean; Ren, Minghua; Reyes-Cortes, Ignacio; Pineda, Jose Alfredo; Saulnier, George; Tarimala, Sowmitri; Walton, John

    2016-10-04

    The Peña Blanca region, 50 km north of Chihuahua City, Chihuahua, México, was a target of uranium exploration and mining by the Mexican government. After mining ceased in 1981, researchers became interested in this region as a study area for subsurface uranium migration with relevance to geologic disposal of nuclear waste. Many studies related to this concept were conducted at the Nopal I mine site located on a cuesta (hill) of the Sierra Peña Blanca. This site has geologic, tectonic, hydrologic, and geochemical similarities to Yucca Mountain, Nevada, a formerly proposed site for a high-level nuclear-waste repository in the unsaturated zone. The U.S. Department of Energy (U.S. DOE), Office of Civilian Radioactive Waste Management (OCRWM), sponsored studies at Nopal I in the 1990s and supported the drilling of three research wells – PB1, PB2, and PB3 – at the site in 2003. Beginning in 2004, the Peña Blanca Natural Analogue Project was undertaken by U.S. DOE, OCRWM to develop a three-dimensional conceptual model of the transport of uranium and its radiogenic daughter products at the Nopal I site.

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

    PubMed Central

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

    2015-01-01

    A series of novel bis-tetrahydropyran 1,4-triazole analogues based on the acetogenin framework display low micromolar trypanocidal activities towards both bloodstream and insect forms of Trypanosoma brucei, the causative agent of African sleeping sickness. 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. PMID:25145275

  19. New synthetic strategies towards psammaplin A, access to natural product analogues for biological evaluation.

    PubMed

    Baud, Matthias G J; Leiser, Thomas; Meyer-Almes, Franz-Josef; Fuchter, Matthew J

    2011-02-07

    New synthetic routes towards the natural product psammaplin A were developed with the particular view to preparing diverse analogues for biological assessment. These routes utilize cheap and commercially available starting materials, and allowed access to psammaplin A analogues not accessible via currently reported methods. Preliminary biological studies revealed these compounds to be the most potent non peptidic inhibitors of the enzyme histone deacetylase 1 (HDAC1, class I) discovered so far. Interestingly, psammaplin A and our synthetic analogues show class I selectivity in vitro, an important feature for the design and synthesis of future isoform selective inhibitors.

  20. Synthesis and biological evaluation of new salvinorin A analogues incorporating natural amino acids.

    PubMed

    Fichna, Jakub; Lewellyn, Kevin; Yan, Feng; Roth, Bryan L; Zjawiony, Jordan K

    2011-01-01

    The synthesis and in vitro evaluation of a new series of salvinorin A analogues substituted at the C(2) position with natural amino acids is reported. Compound 12, containing Val, displayed high affinity and full agonist activity at the kappa-opioid receptor. Analogues with bulky and/or aromatic residues were inactive, showing the importance of size and electronegativity of C(2)-substituents for binding affinity of salvinorin A derivatives.

  1. Sansanmycin natural product analogues as potent and selective anti-mycobacterials that inhibit lipid I biosynthesis

    NASA Astrophysics Data System (ADS)

    Tran, Anh T.; Watson, Emma E.; Pujari, Venugopal; Conroy, Trent; Dowman, Luke J.; Giltrap, Andrew M.; Pang, Angel; Wong, Weng Ruh; Linington, Roger G.; Mahapatra, Sebabrata; Saunders, Jessica; Charman, Susan A.; West, Nicholas P.; Bugg, Timothy D. H.; Tod, Julie; Dowson, Christopher G.; Roper, David I.; Crick, Dean C.; Britton, Warwick J.; Payne, Richard J.

    2017-03-01

    Tuberculosis (TB) is responsible for enormous global morbidity and mortality, and current treatment regimens rely on the use of drugs that have been in use for more than 40 years. Owing to widespread resistance to these therapies, new drugs are desperately needed to control the TB disease burden. Herein, we describe the rapid synthesis of analogues of the sansanmycin uridylpeptide natural products that represent promising new TB drug leads. The compounds exhibit potent and selective inhibition of Mycobacterium tuberculosis, the etiological agent of TB, both in vitro and intracellularly. The natural product analogues are nanomolar inhibitors of Mtb phospho-MurNAc-pentapeptide translocase, the enzyme responsible for the synthesis of lipid I in mycobacteria. This work lays the foundation for the development of uridylpeptide natural product analogues as new TB drug candidates that operate through the inhibition of peptidoglycan biosynthesis.

  2. Sansanmycin natural product analogues as potent and selective anti-mycobacterials that inhibit lipid I biosynthesis

    PubMed Central

    Tran, Anh T.; Watson, Emma E.; Pujari, Venugopal; Conroy, Trent; Dowman, Luke J.; Giltrap, Andrew M.; Pang, Angel; Wong, Weng Ruh; Linington, Roger G.; Mahapatra, Sebabrata; Saunders, Jessica; Charman, Susan A.; West, Nicholas P.; Bugg, Timothy D. H.; Tod, Julie; Dowson, Christopher G.; Roper, David I.; Crick, Dean C.; Britton, Warwick J.; Payne, Richard J.

    2017-01-01

    Tuberculosis (TB) is responsible for enormous global morbidity and mortality, and current treatment regimens rely on the use of drugs that have been in use for more than 40 years. Owing to widespread resistance to these therapies, new drugs are desperately needed to control the TB disease burden. Herein, we describe the rapid synthesis of analogues of the sansanmycin uridylpeptide natural products that represent promising new TB drug leads. The compounds exhibit potent and selective inhibition of Mycobacterium tuberculosis, the etiological agent of TB, both in vitro and intracellularly. The natural product analogues are nanomolar inhibitors of Mtb phospho-MurNAc-pentapeptide translocase, the enzyme responsible for the synthesis of lipid I in mycobacteria. This work lays the foundation for the development of uridylpeptide natural product analogues as new TB drug candidates that operate through the inhibition of peptidoglycan biosynthesis. PMID:28248311

  3. Sansanmycin natural product analogues as potent and selective anti-mycobacterials that inhibit lipid I biosynthesis.

    PubMed

    Tran, Anh T; Watson, Emma E; Pujari, Venugopal; Conroy, Trent; Dowman, Luke J; Giltrap, Andrew M; Pang, Angel; Wong, Weng Ruh; Linington, Roger G; Mahapatra, Sebabrata; Saunders, Jessica; Charman, Susan A; West, Nicholas P; Bugg, Timothy D H; Tod, Julie; Dowson, Christopher G; Roper, David I; Crick, Dean C; Britton, Warwick J; Payne, Richard J

    2017-03-01

    Tuberculosis (TB) is responsible for enormous global morbidity and mortality, and current treatment regimens rely on the use of drugs that have been in use for more than 40 years. Owing to widespread resistance to these therapies, new drugs are desperately needed to control the TB disease burden. Herein, we describe the rapid synthesis of analogues of the sansanmycin uridylpeptide natural products that represent promising new TB drug leads. The compounds exhibit potent and selective inhibition of Mycobacterium tuberculosis, the etiological agent of TB, both in vitro and intracellularly. The natural product analogues are nanomolar inhibitors of Mtb phospho-MurNAc-pentapeptide translocase, the enzyme responsible for the synthesis of lipid I in mycobacteria. This work lays the foundation for the development of uridylpeptide natural product analogues as new TB drug candidates that operate through the inhibition of peptidoglycan biosynthesis.

  4. Synthesis and Neurotrophic Activity Studies of Illicium Sesquiterpene Natural Product Analogues.

    PubMed

    Richers, Johannes; Pöthig, Alexander; Herdtweck, Eberhardt; Sippel, Claudia; Hausch, Felix; Tiefenbacher, Konrad

    2017-03-02

    Neurotrophic natural products hold potential as privileged structures for the development of therapeutic agents against neurodegeneration. However, only a few studies have been conducted to investigate a common pharmacophoric motif and structure-activity relationships (SARs). Here, an investigation of structurally more simple analogues of neurotrophic sesquiterpenes of the illicium family is presented. A concise synthetic route enables preparation of the carbon framework of (±)-Merrilactone A and (±)-Anislactone A/B on a gram scale. This has allowed access to a series of structural analogues by modification of the core structure, including variation of oxidation levels and alteration of functional groups. In total, 15 derivatives of the natural products have been synthesized and tested for their neurite outgrowth activities. Our studies indicate that the promising biological activity can be retained by structurally simpler natural product analogues, which are accessible by a straightforward synthetic route.

  5. Geochemical Fate and Transport of Sildenafil in Natural Soils

    NASA Astrophysics Data System (ADS)

    Turner, A. E.; Vulava, V. M.

    2016-12-01

    In recent years, pharmaceutical drugs have become of increasing concern to the health of our environment. As a result of wastewater treatment plant discharge and various sources of surface runoff, pharmaceuticals can be found in trace amounts in our most common water resources. Sildenafil, a drug marketed to treat erectile dysfunction, is amongst the top 20 most prescribed pharmaceutical products in the U.S. Sildenafil is a complex polar organic molecule with multiple amine functional groups, which gives it acid-base functionality. The most common pKa of this molecule is approximately 6.0 and water solubility ranges from 3.5 to 4.6 mg/L. The goal of this project is to examine the sorption and transport behavior of sildenafil in natural organic matter- (OM) and clay-rich soils. Soils used for this study were collected from undisturbed forested areas in Francis Marion National Forest, Charleston, SC. A series of batch sorption isotherm and column transport experiments were conducted with these soils. Sildenafil was analyzed using high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS) techniques. Batch sorption isotherm experiments produced nonlinear data for both OM- and clay-rich soil types. The data shows that sildenafil sorbs more strongly to the clay-rich soils than to the OM-rich soils. This suggests that sildenafil behaved as a cation and preferentially sorbed with the negatively-charged clay minerals. The transport behavior of sildenafil as determined by experiments with soil-packed glass chromatography columns confirmed this behavior. The resulting breakthrough curves show that sildenafil is strongly retarded in clay-rich soils. Our studies do not show degradation or transformation of sildenafil in soils. The results from this study have strong implications for environmental management of pharmaceutical chemical effluents and disposal.

  6. Natural analogue study of CO2 storage monitoring using probability statistics of CO2-rich groundwater chemistry

    NASA Astrophysics Data System (ADS)

    Kim, K. K.; Hamm, S. Y.; Kim, S. O.; Yun, S. T.

    2016-12-01

    For confronting global climate change, carbon capture and storage (CCS) is one of several very useful strategies as using capture of greenhouse gases like CO2 spewed from stacks and then isolation of the gases in underground geologic storage. CO2-rich groundwater could be produced by CO2 dissolution into fresh groundwater around a CO2 storage site. As consequence, natural analogue studies related to geologic storage provide insights into future geologic CO2 storage sites as well as can provide crucial information on the safety and security of geologic sequestration, the long-term impact of CO2 storage on the environment, and field operation and monitoring that could be implemented for geologic sequestration. In this study, we developed CO2 leakage monitoring method using probability density function (PDF) by characterizing naturally occurring CO2-rich groundwater. For the study, we used existing data of CO2-rich groundwaters in different geological regions (Gangwondo, Gyeongsangdo, and Choongchungdo provinces) in South Korea. Using PDF method and QI (quantitative index), we executed qualitative and quantitative comparisons among local areas and chemical constituents. Geochemical properties of groundwater with/without CO2 as the PDF forms proved that pH, EC, TDS, HCO3-, Ca2+, Mg2+, and SiO2 were effective monitoring parameters for carbonated groundwater in the case of CO2leakage from an underground storage site. KEY WORDS: CO2-rich groundwater, CO2 storage site, monitoring parameter, natural analogue, probability density function (PDF), QI_quantitative index Acknowledgement This study was supported by the "Basic Science Research Program through the National Research Foundation of Korea (NRF), which is funded by the Ministry of Education (NRF-2013R1A1A2058186)" and the "R&D Project on Environmental Management of Geologic CO2 Storage" from KEITI (Project number: 2014001810003).

  7. CO2-rich geothermal areas in Iceland as natural analogues for geologic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Thomas, D.; Maher, K.; Bird, D. K.; Brown, G. E.; Arnorsson, S.

    2013-12-01

    Geologic CO2 sequestration into mafic rocks via silicate mineral dissolution and carbonate precipitation has been suggested as a way to mitigate industrial CO2 emissions by storing CO2 in a stable form. Experimental observations of irreversible reaction of basalt with supercritical or gaseous and aqueous CO2 have resulted in carbonate precipitation, but there are no universal trends linking the extent of mineralization and type of reaction products to the bulk rock composition, glass percentage or mineralogy of the starting material. Additionally, concern exists that CO2 leakage from injection sites and migration through the subsurface may induce mineral dissolution and desorption of trace elements, potentially contaminating groundwater. This study investigates low-temperature (≤180°C) basaltic geothermal areas in Iceland with an anomalously high input of magmatic CO2 as natural analogues of the geochemical processes associated with the injection of CO2 into mafic rocks and possible leakage. Fluids that contain >4 mmol/kg total CO2 are common along the divergent Snæfellsnes Volcanic Zone in western Iceland and within the South Iceland Seismic Zone in southwest Iceland. The meteorically derived waters contain up to 80 mmol/kg dissolved inorganic carbonate (DIC). The aqueous concentration of major cations and trace elements is greater than that in Icelandic surface and groundwater and increases with DIC and decreasing pH. Concentrations of As and Ni in some samples are several times the World Health Organization (WHO) guidelines for safe drinking water. Thermodynamic modeling indicates that waters approach saturation with respect to calcite and/or aragonite, kaolinite and amorphous silica, and are undersaturated with respect to plagioclase feldspar, clinozoisite and Ca-zeolites. Petrographic study of drill cuttings from wells that intersect the CO2-rich areas indicates that the sites have undergone at least two stages of hydrothermal alteration: initial high

  8. Comparison of natural aquifer geochemical variability with uncertainty from model-predicted CO2 induced geochemical changes: How detectable is leakage from carbon sequestration sites?

    NASA Astrophysics Data System (ADS)

    Navarre-Sitchler, A. K.; Moore, J.

    2012-12-01

    Leakage of CO2 from underground formations poses risk to the storage permanence goal of 99% of injected CO2 remaining sequestered from the atmosphere, which is needed to mitigate potential global climate change. Additionally, leaked CO2 that invades overlying shallow aquifers may cause deleterious changes to groundwater quality and pose risks to environmental and human health. For these reasons, technologies for monitoring, measurement and accounting of injected CO2 are necessary for regulation and permitting of CO2 sequestration operations. Changes in groundwater geochemistry induced by CO2 leakage offer a potential diagnostic tool for identifying leakage into shallow aquifers. In order to confidently use geochemical parameters as indicators of leakage, however, natural variability in geochemical concentrations and uncertainty in predicted geochemical changes induced by CO2 leakage must be quantitatively evaluated. For leakage monitoring, spatial variability of geochemical parameters such as alkalinity, pH, and specific conductivity is less relevant than temporal variability of these parameters within a given well. We used geochemical data from the Ohio Environmental Protection Agency, Ambient Ground Water Monitoring Network to characterize geochemical variability within individual wells. We selected wells from limestone, sandstone, and unconsolidated aquifers with ≥15 samples (typically annual) and statistically analyzed variability in alkalinity, pH, and specific conductance using median and interquartile range (IQR) to avoid influence by outliers and non-gaussian distributions. Neither the medians nor the IQRs showed correlation with well depth, sampling month, or number of samples. Our results indicate that variability in alkalinity and pH (4 - 12%) within individual wells is lower than specific conductance (28 - 32%), and thus, alkalinity and pH potentially provide more robust indicators. Uncertainty in predicted alkalinity and pH changes due to uncertainty

  9. 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

  10. Natural analogues for processes affecting disposal of high-level radioactive waste in the vadose zone

    NASA Astrophysics Data System (ADS)

    Stuckless, J. S.

    2003-04-01

    Natural analogues can contribute to understanding and predicting the performance of subsystems and processes affecting a mined geologic repository for high-level radioactive waste in several ways. Most importantly, analogues provide tests for various aspects of systems of a repository at dimensional scales and time spans that cannot be attained by experimental study. In addition, they provide a means for the general public to judge the predicted performance of a potential high-level nuclear waste repository in familiar terms such that the average person can assess the anticipated long-term performance and other scientific conclusions. Hydrologists working on the Yucca Mountain Project (currently the U.S. Department of Energy's Office of Repository Development) have modeled the flow of water through the vadose zone at Yucca Mountain, Nevada and particularly the interaction of vadose-zone water with mined openings. Analogues from both natural and anthropogenic examples confirm the prediction that most of the water moving through the vadose zone will move through the host rock and around tunnels. This can be seen both quantitatively where direct comparison between seepage and net infiltration has been made and qualitatively by the excellent degree of preservation of archaeologic artifacts in underground openings. The latter include Paleolithic cave paintings in southwestern Europe, murals and artifacts in Egyptian tombs, painted subterranean Buddhist temples in India and China, and painted underground churches in Cappadocia, Turkey. Natural analogues also suggest that this diversion mechanism is more effective in porous media than in fractured media. Observations from natural analogues are also consistent with the modeled decrease in the percentage of infiltration that becomes seepage with a decrease in amount of infiltration. Finally, analogues, such as tombs that have ben partially filled by mud flows, suggest that the same capillary forces that keep water in the

  11. Synthesis and characterization of a small analogue of the anticancer natural product leinamycin.

    PubMed

    Keerthi, Kripa; Rajapakse, Anuruddha; Sun, Daekyu; Gates, Kent S

    2013-01-01

    Leinamycin (1) is a Streptomyces-derived natural product that displays nanomolar IC(50) values against human cancer cell lines. In the work described here, we report the synthesis and characterization of a small leinamycin analogue 19 that closely resembles the 'upper-right quadrant' of the natural product, consisting of an alicyclic 1,2-dithiolan-3-one 1-oxide heterocycle connected to an alkene by a two-carbon linker. The results indicate that this small analogue contains the core set of functional groups required to enable thiol-triggered generation of both redox active polysulfides and an episulfonium ion intermediate via the complex reaction cascade first seen in the natural product leinamycin. The small leinamycin analogue 19 caused thiol-triggered oxidative DNA strand cleavage in a manner similar to the natural product, but did not alkyate duplex DNA effectively. This highlights the central role of the 18-membered macrocycle of leinamycin in driving efficient DNA alkylation by the natural product.

  12. 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

  13. 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

  14. 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.

  15. 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

    2016-07-29

    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.

  16. 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.

  17. Characterisation of the bio-mineralogical and isotope geochemical signatures of past life in a Mars analogue environment of Rio Tinto, SW of Spain

    NASA Astrophysics Data System (ADS)

    Velasco, E.; Mason, P.; Vroon, P.; Röling, W.; Amils, R.; Davies, G. R.

    2012-09-01

    Iron-rich sulfate minerals are present on Mars hence sulfur, oxygen and iron isotopes could be a key tool for the detection of any past or present life. Experiments with flow through reactors and enrichment cultures have been conducted to investigate the link between the activity of microbial communities and sulfur, oxygen and iron isotope fractionation in Martian like minerals. Sediments from a modern hyper-acidic, Fe-rich subareal environment at Rio Tinto, SW Spain were used in the experiments. This site has been frequently used as a geochemical analogue of Mars. Sediments were sampled from the upper part of Rio Tinto (Marismilla) and the estuary (Moguer). Laboratory incubations were carried out at 30°C, using an artificial input solution with sulfate in excess [1]. Initial data from the flow through reactor experiments indicate an extreme sulfur isotope fractionation in the Moguer estuarine part, extending beyond the maximum of 47‰ predicted by the standard Rees model [2]. These data suggest that, at least, sulfur isotopes have a potential to be sensitive indicators of biotic activity in Martian environments that contain sulfate minerals.

  18. Potential impacts on groundwater resources of deep CO2 storage: natural analogues for assessing potential chemical effects

    NASA Astrophysics Data System (ADS)

    Lions, J.; Gale, I.; May, F.; Nygaard, E.; Ruetters, H.; Beaubien, S.; Sohrabi, M.; Hatzignatiou, D. G.; CO2GeoNet Members involved in the present study Team

    2011-12-01

    Carbon dioxide Capture and Storage (CCS) is considered as one of the promising options for reducing atmospheric emissions of CO2 related to human activities. One of the main concerns associated with the geological storage of CO2 is that the CO2 may leak from the intended storage formation, migrate to the near-surface environment and, eventually, escape from the ground. This is a concern because such leakage may affect aquifers overlying the storage site and containing freshwater that may be used for drinking, industry and agriculture. The IEA Greenhouse Gas R&D Programme (IEAGHG) recently commissioned the CO2GeoNet Association to undertake a review of published and unpublished literature on this topic with the aim of summarizing 'state of the art' knowledge and identifying knowledge gaps and research priorities in this field. Work carried out by various CO2GeoNet members was also used in this study. This study identifies possible areas of conflict by combining available datasets to map the global and regional superposition of deep saline formations (DSF) suitable for CO2 storage and overlying fresh groundwater resources. A scenario classification is developed for the various geological settings where conflict could occur. The study proposes two approaches to address the potential impact mechanisms of CO2 storage projects on the hydrodynamics and chemistry of shallow groundwater. The first classifies and synthesizes changes of water quality observed in natural/industrial analogues and in laboratory experiments. The second reviews hydrodynamic and geochemical models, including coupled multiphase flow and reactive transport. Various models are discussed in terms of their advantages and limitations, with conclusions on possible impacts on groundwater resources. Possible mitigation options to stop or control CO2 leakage are assessed. The effect of CO2 pressure in the host DSF and the potential effects on shallow aquifers are also examined. The study provides a review of

  19. 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.

  20. 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.

  1. 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

  2. Flavone-based analogues inspired by the natural product simocyclinone D8 as DNA gyrase inhibitors.

    PubMed

    Verghese, Jenson; Nguyen, Thuy; Oppegard, Lisa M; Seivert, Lauren M; Hiasa, Hiroshi; Ellis, Keith C

    2013-11-01

    The increasing occurrence of drug-resistant bacterial infections in the clinic has created a need for new antibacterial agents. Natural products have historically been a rich source of both antibiotics and lead compounds for new antibacterial agents. The natural product simocyclinone D8 (SD8) has been reported to inhibit DNA gyrase, a validated antibacterial drug target, by a unique catalytic inhibition mechanism of action. In this work, we have prepared simplified flavone-based analogues inspired by the complex natural product and evaluated their inhibitory activity and mechanism of action. While two of these compounds do inhibit DNA gyrase, they do so by a different mechanism of action than SD8, namely DNA intercalation.

  3. 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

  4. Geochemical processes controlling fate and transport of arsenic in acid mine drainage (AMD) and natural systems.

    PubMed

    Cheng, Hefa; Hu, Yuanan; Luo, Jian; Xu, Bin; Zhao, Jianfu

    2009-06-15

    Acid mine drainage (AMD) is often accompanied with elevated concentrations of arsenic, in the forms of arsenite, As(III), and/or arsenate, As(V), due to the high affinity of arsenic for sulfide mineral ores. This review summarizes the major geochemical processes controlling the release, speciation, fate, and distribution of inorganic arsenic in mine drainage and natural systems. Arsenic speciation depends highly on redox potential and pH of the solution, and arsenite can be oxidized to the less toxic arsenate form. Homogeneous oxidation of arsenite occurs rather slowly while its heterogeneous oxidation on mineral surfaces can greatly enhance the reaction rates. Little evidence suggests that precipitation reaction limits the concentrations of arsenic in natural water, while co-precipitation may lead to rapid arsenic removal when large amount of iron hydroxides precipitate out of the aqueous phase upon neutralization of the mine drainage. Both arsenate and arsenite adsorb on common metal oxides and clay minerals through formation of inner-sphere and/or outer-sphere complexes, controlling arsenic concentration in natural water bodies. Arsenite adsorbs less strongly than arsenate in the typical pH range of natural water and is more mobile. Part of the adsorbed arsenic species can be exchanged by common anions (e.g., PO(4)(3-) and SO(4)(2-)), especially phosphate, which leads to their re-mobilization. Understanding the geochemistry of arsenic is helpful for predicting its mobility and fate in AMD and natural systems, and for designing of cost-effective remediation/treatment strategies to reduce the occurrence and risk of arsenic contamination.

  5. 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.

  6. 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

  7. 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

  8. Metabolic engineering and in vitro biosynthesis of phytochemicals and non-natural analogues.

    PubMed

    Mora-Pale, Mauricio; Sanchez-Rodriguez, Sandra P; Linhardt, Robert J; Dordick, Jonathan S; Koffas, Mattheos A G

    2013-09-01

    Over the years, natural products from plants and their non-natural derivatives have shown to be active against different types of chronic diseases. However, isolation of such natural products can be limited due to their low bioavailability, and environmental restrictions. To address these issues, in vivo and in vitro reconstruction of plant metabolic pathways and the metabolic engineering of microbes and plants have been used to generate libraries of compounds. Significant advances have been made through metabolic engineering of microbes and plant cells to generate a variety of compounds (e.g. isoprenoids, flavonoids, or stilbenes) using a diverse array of methods to optimize these processes (e.g. host selection, operational variables, precursor selection, gene modifications). These approaches have been used also to generate non-natural analogues with different bioactivities. In vitro biosynthesis allows the synthesis of intermediates as well as final products avoiding post-translational limitations. Moreover, this strategy allows the use of substrates and the production of metabolites that could be toxic for cells, or expand the biosynthesis into non-conventional media (e.g. organic solvents, supercritical fluids). A perspective is also provided on the challenges for generating novel chemical structures and the potential of combining metabolic engineering and in vitro biocatalysis to produce metabolites with more potent biological activities. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. Nematicidal activity of natural ester compounds and their analogues against pine wood nematode, Bursaphelenchus xylophilus.

    PubMed

    Seo, Seon-Mi; Kim, Junheon; Koh, Sang-Hyun; Ahn, Young-Joon; Park, Il-Kwon

    2014-09-17

    In this study, we evaluated the nematicidal activity of natural ester compounds against the pine wood nematode, Bursaphelenchus xylophilus, to identify candidates for the development of novel, safe nematicides. We also tested the nematicidal activity of synthesized analogues of these ester compounds to determine the structure-activity relationship. Among 28 ester compounds tested, isobutyl 2-methylbutanoate, 3-methylbutyl 2-methylbutanoate, 3-methylbutyl tiglate, 3-methyl-2-butenyl 2-methylbutanoate, and pentyl 2-methylbutanoate showed strong nematicidal activity against the pine wood nematode at a 1 mg/mL concentration. The other ester compounds showed weak nematicidal activity. The LC50 values of 3-methylbutyl tiglate, isobutyl 2-methylbutanoate, 3-methylbutyl 2-methylbutanoate, 3-methyl-2-butenyl 2-methylbutanoate, and pentyl 2-methylbutanoate were 0.0218, 0.0284, 0.0326, 0.0402, and 0.0480 mg/mL, respectively. The ester compounds described herein merit further study as potential nematicides for pine wood nematode control.

  10. Crystallization and Stress Relaxation in Highly Stretched Samples of Natural Rubber and its Synthetic Analogue

    SciTech Connect

    Tosaka,M.; Kawakami, D.; Senoo, K.; Kohjiya, S.; Toki, S.; Hsiao, B.

    2006-01-01

    Vulcanizates of natural rubber (NR) and its synthetic analogue (IR) were quickly stretched to 6 times the original length. The post stretch relaxation of tensile stress and the development of strain-induced crystallization (SIC) were studied by simultaneous measurements of the stress and the diffraction intensities using the synchrotron X-ray source. In the range of 8 s, NR crystallized much faster than IR. Accordingly, the origin of the superior toughness of NR was thought to come from the ability of rapid SIC. Time constants of the post-stretch crystallization were estimated from the X-ray study. Then the crystallization time constants were used to decompose the contribution of SIC from the total magnitude of the post-stretch relaxation. The contribution of SIC was dominant for the total magnitude of the post-stretch relaxation during several seconds.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. The comparative toxicity to soil invertebrates of natural chemicals and their synthetic analogues.

    PubMed

    Whitaker, J; Chaplow, J S; Potter, E; Scott, W A; Hopkin, S; Harman, M; Sims, I; Sorokin, N

    2009-07-01

    The introduction of Registration, Evaluation and Authorisation of Chemicals (REACH), requires companies to register and risk assess all substances produced or imported in volumes of >1 tonne per year. Extrapolation methods which use existing data for estimating the effects of chemicals are attractive to industry, and comparative data are therefore increasingly in demand. Data on natural toxic chemicals could be used for extrapolation methods such as read-across. To test this hypothesis, the toxicity of natural chemicals and their synthetic analogues were compared using standardised toxicity tests. Two chemical pairs: the napthoquinones, juglone (natural) and 1,4-naphthoquinone (synthetic); and anthraquinones, emodin (natural) and quinizarin (synthetic) were chosen, and their comparative effects on the survival and reproduction of collembolans, earthworms, enchytraeids and predatory mites were assessed. Differences in sensitivity between the species were observed with the predatory mite (Hypoaspis aculeifer) showing the least sensitivity. Within the chemical pairs, toxicity to lethal and sub-lethal endpoints was very similar for the four invertebrate species. The exception was earthworm reproduction, which showed differential sensitivity to the chemicals in both naphthoquinone and anthraquinone pairs. Differences in toxicity identified in the present study may be related to degree of exposure and/or subtle differences in the mode of toxic action for the chemicals and species tested. It may be possible to predict differences by identifying functional groups which infer increased or decreased toxicity in one or other chemical. The development of such techniques would enable the use of read-across from natural to synthetic chemicals for a wider group of compounds.

  16. Geochemical Composition of Surface Water in the Mineralized Lom Basin, East Cameroon: Natural and Anthropogenic Sources.

    NASA Astrophysics Data System (ADS)

    Mimba, M. E.; Ohba, T.; Nguemhe Fils, S. C.; Wirmvem, M. J.

    2016-12-01

    Thousands of people in East Cameroon depend on surface water for consumption and domestic purposes. The Lom basin, north of the region, is heavily mineralized especially in gold owing to its regional geological setting. Although research has been done regarding the rock type, age, formation history and reconnaissance gold surveys, surface water investigation in the area has received limited attention. Thus, this study appraises the first regional hydrogeochemical program for environmental assessment of the mineralized Lom basin. Fifty-two representative stream water samples were collected under base flow conditions and analysed for major cations (Ca2+, Mg2+, Na+, K+ ), major anions (HCO3-, F-, Cl-, NO2-, NO3-, Br-, PO43-, SO42- ) and stable isotopes (δD and δ18O). Calcium and HCO3- were the dominant ions. The chemical facies were CaHCO3 and NaHCO3 indicating surface water draining igneous/metamorphic rocks in hot and humid equatorial climate, resulting in the discordant dissolution of primary silicate minerals. From the isotopic evaluation, the stream water is of meteoric origin, shows negligible evaporation effect and has a common recharge source. The major ion geochemistry demonstrated the potential to discriminate between natural and anthropogenic origins. Distribution trends of Ca2+, Mg2+, Na+, K+, HCO3- and SO42- showed a correlation with the lithology and the occurrence of sulphide minerals associated with hydrothermal gold mineralization in the area. The distribution patterns of NO3- and Cl- reflect pollution from settlement. Overall, the chemistry of stream water in the Lom basin is mainly controlled by rock weathering compared to anthropogenic influence. Surface water quality is easily influenced by anthropogenic activities, and stream sediment collects effectively trace metals resulting from such activities. Hence, geochemical mapping incorporating stream water and stream sediment is of considerable value in future investigations within the Lom basin.

  17. Function-Oriented Synthesis: How to Design Simplified Analogues of Antibacterial Nucleoside Natural Products?

    PubMed

    Ichikawa, Satoshi

    2016-06-01

    It is important to pursue function-oriented synthesis (FOS), a strategy for the design of less structurally complex targets with comparable or superior activity that can be made in a practical manner, because compared to synthetic drugs, many biologically relevant natural products possess large and complex chemical structures that may restrict chemical modifications in a structure-activity relationship study. In this account, we describe recent efforts to simplify complex nucleoside natural products including caprazamycins. Considering the structure-activity relationship study with several truncated analogues, three types of simplified derivatives, namely, oxazolidine, isoxazolidine, and lactam-fused isoxazolidine-containing uridine derivatives, were designed and efficiently synthesized. These simplified derivatives have exhibited promising antibacterial activities. A significant feature of our studies is the rational and drastic simplification of the molecular architecture of caprazamycins. This study provides a novel strategy for the development of a new type of antibacterial agent effective against drug-resistant bacteria. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. 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

  19. XAFS And Molecular Dynamics Study of Natural Minerals, Analogues of Ceramics for Nuclear Waste Storage

    SciTech Connect

    Harfouche, M.; Farges, F.; Crocombette, J.P.; Flank, A.M.; /SLAC, SSRL

    2006-10-27

    Natural actinides (U and Th) are harmful for the crystalline structure of natural minerals, due to their irradiation. Natural minerals can then become amorphous to x-ray diffraction ('metamict') after being irradiated throughout a long period of time (10{sup 8} years). Then, they are used as natural analogues of ceramics for nuclear waste storage. XAFS studies were performed in zircon, monazite and titanite to understand the effect of radiation damage on the local structure around Th, U, Zr and P and compared to available molecular dynamics (MD) simulations. In zircon, a local expansion around actinides (when substituting for Zr) is found. The radial expansion is a function of the metamictisation degree: up to {approx}4 {angstrom} in crystalline zircon and larger in the metamict counterparts. Ab-initio calculations (FEFF7) were performed around Zr ({approx}23000 sites) and around U (1000 to 3000 sites) in various crystalline and alpha-decay damaged zircon MD simulations. The calculated averaged EXAFS spectra confirms this expansion, which validates the use of the potentials used in the simulations as well as the alpha decay damage model considered in these MD simulations. Tetravalent actinides were found to be 8-coordinated in the undamaged structure, whereas their coordination drops to 7 in the damaged structures. In contrast to zircon, no local expansion around actinides in monazite was detected, despite some polymerization around P is measured (related to radiation damage). Finally, in some phases (such as titanite), actinides are found as oxyde-type clusters (ThO{sub 2}, UO{sub 2}). Consequently, actinides do not 'systematically' substitute for major actions in these structure, in contrast to the common belief in mineralogy.

  20. Geochemical Controls on Natural Attenuation of Arsenic Solubilized by Human-Induced Alterations

    NASA Astrophysics Data System (ADS)

    Bilgin, A.; Hering, J. G.; Harrington, J.; Horst, J.; Burris, D.; Reisinger, H. J.

    2005-12-01

    Naturally-occurring arsenic (As) in soils can be solubilized into groundwater as a result of anthropogenic changes in subsurface redox conditions. However, the presence of As in groundwater may not lead to human exposure if As is attenuated before intercepting a water source. Dissolved As can be attenuated by sorption and precipitation processes whose effectiveness may be strongly influenced by redox transformations. Anaerobic bioremediation has been employed at a site in the Northeastern U.S. to treat a tetrachloroethene (PCE) plume in groundwater. An organic carbon source is injected via a transect of wells oriented perpendicular to groundwater flow. The resulting anaerobic reducing zone extends 30 meters down gradient of the injection transect. At the down gradient edge of the reducing zone, dissolved As and Fe concentrations have been observed at over 0.7 milligrams per liter (mg/L) and 450 mg/L, respectively. However, 60 m down gradient (and outside of the reducing zone), As and Fe concentrations have been maintained at levels below their detection limits (0.005 mg/L and 1 mg/L) for over 900 days, demonstrating natural attenuation of As. The sorption of As onto Fe and Mn oxyhydroxides under changing geochemical conditions is investigated by using the reactive transport modeling program Geochemist's Work Bench (GWB). Down gradient conditions are simulated where reduced constituents of contaminated groundwater react with Fe(III) and Mn(III, IV) oxyhydroxides in the soil/aquifer matrix or with dissolved oxygen in uncontaminated groundwater at the periphery of the reducing zone. Dissolved Fe(II) and Mn(II) are re-oxidized and precipitate as oxyhydroxide coatings on the soil or aquifer sediments. These coatings then serve as sorbents for both As(III) and As(V). Simulations allow us to examine As sequestration as a function of groundwater composition (e.g., pH and competing sorbates such as phosphate) and of the rate and extent of the precipitation of Fe(III) and Mn

  1. 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

  2. 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.

  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. 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.

  5. 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.

  6. 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.

  7. Total Synthesis of Vinblastine, Vincristine, Related Natural Products, and Key Structural Analogues

    PubMed Central

    Ishikawa, Hayato; Colby, David A.; Seto, Shigeki; Va, Porino; Tam, Annie; Kakei, Hiroyuki; Rayl, Thomas J.; Hwang, Inkyu; Boger, Dale L.

    2009-01-01

    Full details of the development of a direct coupling of catharanthine with vindoline to provide vinblastine are described along with key mechanistic and labeling studies. Following an Fe(III)-promoted coupling reaction initiated by generation of a presumed catharanthine radical cation that undergoes a subsequent oxidative fragmentation and diastereoselective coupling with vindoline, addition of the resulting reaction mixture to an Fe(III)–NaBH4/air solution leads to oxidation of the C15′–C20′ double bond and reduction of the intermediate iminium ion directly providing vinblastine (40–43%) and leurosidine (20–23%), its naturally occurring C20′ alcohol isomer. The yield of coupled products, which exclusively possess the natural C16′ stereochemistry, approaches or exceeds 80% and the combined yield of the isomeric C20′ alcohols is >60%. Preliminary studies of Fe(III)–NaBH4/air oxidation reaction illustrate a generalizable trisubstituted olefin scope, identified alternatives to O2 trap at the oxidized carbon, provides a unique entry into C20′ functionalized vinblastines, and affords initial insights into the observed C20′ diastereoselectivity. The first disclosure of the use of exo-catharanthine proceeding through Δ19′,20′-anhydrovinblastine in such coupling reactions is also detailed with identical stereochemical consequences. Incorporating either a catharanthine N-methyl group or a vindoline N-formyl group precludes Fe(III)-promoted coupling, whereas the removal of the potentially key C16 methoxy group of vindoline does not adversely impact the coupling efficiency. Extension of these studies provided a total synthesis of vincristine (2) via N-desmethylvinblastine (36, also a natural product), 16-desmethoxyvinblastine (44) and 4-desacetoxy-16-desmethoxyvinblastine (47) both of which we can now suggest are likely natural products produced by C. roseus, desacetylvinblastine (62) and 4-desacetoxyvinblastine (59), as well as a series of key

  8. 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.

  9. 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.

  10. Decomposition of sodium formate and L- and D-alanine in the Pampas de La Joya soils: Implications as a new geochemical analogue to Martian regolith

    NASA Astrophysics Data System (ADS)

    Valdivia-Silva, Julio E.; Navarro-González, Rafael; Rosa, José De La; McKay, Christopher P.

    2012-03-01

    The organic compounds on the Martian surface are still undetectable by the previous Viking mission that has been sent to Mars even though they are expected to be there by exogenous and/or endogenous synthesis. The high abiotic reactivity has been the most acceptable explanation for the apparently absence of organic matter in the regolith.Earth soils that have geochemical properties similar to those expected on the surface of Mars could help to decipher this question on the surface and shallow subsurface of the Red Planet. This work aims to demonstrate that the place known as the Pampas de La Joya desert in southern Peru, contains soils that have nonbiological chemical decomposition mechanisms of organic compounds under conditions of the Viking Labeled Release Experiment (LRx). We compare the organic decomposition kinetics of these hyper-arid soils with those seen in samples from arid and semiarid regions of the Atacama Desert, and data obtained by Viking LRx in the Martian regolith. 13Carbon-labeled organic compounds (sodium formate, D-, and L-alanine) were added in aqueous solution to different soil samples in order to analyze the evolved carbon dioxide (13CO2) generated during their degradation. As expected, there were significant differences in the evolved gas behavior between soil samples under similar experimental conditions. When sodium formate was added to hyper-arid samples, there was a peak of 13CO2 gas released demonstrating high oxidation activity in the soil. Heat treatment of soil samples did not completely eliminate the CO2 production. An increase in the decomposition rates ˜7 days after the first addition of organics showed a response consistent with biological activity. The addition of D- and L-alanine demonstrated that the production of 13CO2 due to biological decomposition began 5-8 days after incubation. Our results suggest that these soils from Pampas de La Joya present at least two types of oxidants, a thermostable one which is highly

  11. 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

  12. Natural and Semisynthetic Analogues of Manadoperoxide B Reveal New Structural Requirements for Trypanocidal Activity

    PubMed Central

    Chianese, Giuseppina; Scala, Fernando; Calcinai, Barbara; Cerrano, Carlo; Dien, Henny A.; Kaiser, Marcel; Tasdemir, Deniz; Taglialatela-Scafati, Orazio

    2013-01-01

    Chemical analysis of the Indonesian sponge Plakortis cfr. lita afforded two new analogues of the potent trypanocidal agent manadoperoxide B (1), namely 12-isomanadoperoxide B (2) and manadoperoxidic acid B (3). These compounds were isolated along with a new short chain dicarboxylate monoester (4), bearing some interesting relationships with the polyketide endoperoxides found in this sponge. Some semi-synthetic analogues of manadoperoxide B (6–8) were prepared and evaluated for antitrypanosomal activity and cytotoxicity. These studies revealed crucial structure–activity relationships that should be taken into account in the design of optimized and simplified endoperoxyketal trypanocidal agents. PMID:23989650

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. Radon in underground waters as a natural analogue to study the escape of CO2 in geological repositories.

    PubMed

    Martín Sánchez, A; Ruano Sánchez, A B; de la Torre Pérez, J; Jurado Vargas, M

    2015-11-01

    Activity concentrations of dissolved (222)Rn and (226)Ra were measured in several underground aquifers, which are candidates for repositories or for the study of analogue natural escapes of CO2. The concentration of both radionuclides in water was determined using liquid scintillation counting. The values obtained for the (222)Rn concentrations varied from 0 to 150 Bq l(-1), while the levels of (226)Ra were in general very low. This indicates that (222)Rn is coming from the decay of the undissolved (226)Ra existing in the rocks and deep layers of the aquifers, being later transported by diffusion in water.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. Contributions of natural arsenic sources to surface waters on a high grade arsenic-geochemical anomaly (French Massif Central).

    PubMed

    Bossy, A; Grosbois, C; Hendershot, W; Beauchemin, S; Crouzet, C; Bril, H

    2012-08-15

    The subwatershed studied drains a non-exploited area of the St-Yrieix-la-Perche gold mining district (French Massif Central) and it is located on an arsenic (As) geochemical anomaly. In this context, it is important to know the geochemical processes involved in the transfer of As from solid environmental compartments to the aquatic system. The stream showed a temporal variation of dissolved As (As(d)) content from 69.4 μg.L(-1) in the low flow period to 7.5 μg.L(-1) in the high flow period. Upstream, ground- and wetland waters had As(d) concentrations up to 215 and 169 μg.L(-1), respectively. The main representative As sources were determined at the subwatershed scale with in-situ monitoring of major and trace element contents in different waters and single extraction experiments. The As sources to stream water could be regrouped into two components: (i) one As-rich group (mainly in the low flow period) with groundwater, gallery exploration outlet waters and wetland waters, and (ii) one As-poor group (mainly in the high flow period) with rainwaters and soil solutions. In the soil profile, As(d) showed a significant decrease from 52.4 μg.L(-1) in the 0-5 cm superficial soil horizon to 14.4 μg.L(-1) in the 135-165 cm deep soil horizon. This decrease may be related to pedogenic processes and suggests an evolution of As-bearing phase stability through the soil profile. Quantification of As(d) fluxes at the subwatershed scale showed that groundwater was the major input (>80%) of As(d) to surface water. Moreover, natural weathering of the As-rich solid phases showed an impact on the As release, mainly from superficial soil horizons with runoff contributing about 5% to As input in surface water.

  3. 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.

    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.

  4. 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.

  5. Revisiting AI-2 quorum sensing inhibitors: direct comparison of alkyl-DPD analogues and a natural product fimbrolide.

    PubMed

    Lowery, Colin A; Abe, Takumi; Park, Junguk; Eubanks, Lisa M; Sawada, Daisuke; Kaufmann, Gunnar F; Janda, Kim D

    2009-11-04

    Quorum sensing (QS) systems have been discovered in a wide variety of bacteria, and mediate both intra- and interspecies communication. The AI-2-based QS system represents the most studied of these proposed interspecies systems and has been shown to regulate diverse functions such as bioluminescence, expression of virulence factors, and biofilm formation. As such, the development of modulatory compounds, both agonists and antagonists, is of great interest for the study of unknown AI-2-based QS systems and the potential treatment of bacterial infections. The fimbrolide class of natural products has exhibited excellent inhibitory activity against AI-2-based QS and as such may be considered the "gold standard" of AI-2 inhibitors. Thus, we sought to include a fimbrolide as a control compound for our recently developed alkyl-DPD panel of AI-2 modulators. Herein, we present a revised synthesis of a commonly studied fimbrolide as well as a direct comparison between the fimbrolide and alkyl-DPD analogues. We demonstrate that our alkyl-DPD analogues are more potent inhibitors of QS in both Vibrio harveyi and Salmonella typhimurium, the two organisms with defined AI-2 QS systems, and in doing so call into question the widely accepted use of fimbrolide-derived compounds as the "gold standard" of AI-2 inhibition.

  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. Photo-affinity labelling and biochemical analyses identify the target of trypanocidal simplified natural product analogues.

    PubMed

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

    2017-09-05

    Current drugs to treat African sleeping sickness are inadequate and new therapies are urgently required. As part of a medicinal chemistry programme based upon the simplification of acetogenin-type ether scaffolds, we previously reported the promising trypanocidal activity of compound 1, a bis-tetrahydropyran 1,4-triazole (B-THP-T) inhibitor. This study aims to identify the protein target(s) of this class of compound in Trypanosoma brucei to understand its mode of action and aid further structural optimisation. We used compound 3, a diazirine- and alkyne-containing bi-functional photoaffinity probe analogue of our lead B-THP-T, compound 1, to identify potential targets of our lead compound in the procyclic form T. brucei. Bi-functional compound 3 was UV cross-linked to its target(s) in vivo and biotin affinity or Cy5.5 reporter tags were subsequently appended by Cu(II)-catalysed azide-alkyne cycloaddition. The biotinylated protein adducts were isolated with streptavidin affinity beads and subsequent LC-MSMS identified the FoF1-ATP synthase (mitochondrial complex V) as a potential target. This target identification was confirmed using various different approaches. We show that (i) compound 1 decreases cellular ATP levels (ii) by inhibiting oxidative phosphorylation (iii) at the FoF1-ATP synthase. Furthermore, the use of GFP-PTP-tagged subunits of the FoF1-ATP synthase, shows that our compounds bind specifically to both the α- and β-subunits of the ATP synthase. The FoF1-ATP synthase is a target of our simplified acetogenin-type analogues. This mitochondrial complex is essential in both procyclic and bloodstream forms of T. brucei and its identification as our target will enable further inhibitor optimisation towards future drug discovery. Furthermore, the photo-affinity labeling technique described here can be readily applied to other drugs of unknown targets to identify their modes of action and facilitate more broadly therapeutic drug design in any pathogen or

  8. 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.

  9. Diosgenone synthesis, anti-malarial activity and QSAR of analogues of this natural product.

    PubMed

    Pabón, Adriana; Escobar, Gustavo; Vargas, Esteban; Cruz, Víctor; Notario, Rafael; Blair, Silvia; Echeverri, Fernando

    2013-03-14

    Solanum nudum Dunal steroids have been reported as being antimalarial compounds; however, their concentration in plants is low, meaning that the species could be threatened by over-harvesting for this purpose. Swern oxidation was used for hemisynthesis of diosgenone (one of the most active steroidal sapogenin diosgenin compounds). Eighteen structural analogues were prepared; three of them were found to be more active than diosgenone (IC50 27.9 μM vs. 10.1 μM, 2.9 μM and 11.3 μM). The presence of a 4-en-3-one grouping in the A-ring of the compounds seems to be indispensable for antiplasmodial activity; progesterone (having the same functional group in the steroid A-ring) has also displayed antiplasmodial activity. Quantitative correlations between molecular structure and bioactivity were thus explored in diosgenone and several derivatives using well-established 3D-QSAR techniques. The models showed that combining electrostatic (70%) and steric (30%) fields can explain most variance regarding compound activity. Malarial parasitemia in mice became reduced by oral administration of two diosgenone derivatives.

  10. Sinefungin, a natural nucleoside analogue of S-adenosylmethionine, inhibits Streptococcus pneumoniae biofilm growth.

    PubMed

    Yadav, Mukesh Kumar; Park, Seok-Won; Chae, Sung-Won; Song, Jae-Jun

    2014-01-01

    Pneumococcal colonization and disease is often associated with biofilm formation, in which the bacteria exhibit elevated resistance both to antibiotics and to host defense systems, often resulting in infections that are persistent and difficult to treat. We evaluated the effect of sinefungin, a nucleoside analogue of S-adenosylmethionine, on pneumococcal in vitro biofilm formation and in vivo colonization. Sinefungin is bacteriostatic to pneumococci and significantly decreased biofilm growth and inhibited proliferation and structure of actively growing biofilms but did not alter growth or the matrix structure of established biofilms. Sinefungin significantly reduced pneumococcal colonization in rat middle ear. The quorum sensing molecule (autoinducer-2) production was significantly reduced by 92% in sinefungin treated samples. The luxS, pfs, and speE genes were downregulated in biofilms grown in the presence of sinefungin. This study shows that sinefungin inhibits pneumococcal biofilm growth in vitro and colonization in vivo, decreases AI-2 production, and downregulates luxS, pfs, and speE gene expressions. Therefore, the S-adenosylmethionine (SAM) inhibitors could be used as lead compounds for the development of novel antibiofilm agents against pneumococci.

  11. 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.

  12. Microbial effects on the release and attenuation of arsenic in the shallow subsurface of a natural geochemical anomaly.

    PubMed

    Drahota, Petr; Falteisek, Lukáš; Redlich, Aleš; Rohovec, Jan; Matoušek, Tomáš; Cepička, Ivan

    2013-09-01

    Critical factors leading to arsenic release and attenuation from the shallow subsurface were studied with multidisciplinary approach in the natural gold-arsenic geochemical anomaly at Mokrsko (Czech Republic). The results show that microbial reduction promotes arsenic release from Fe(III) (hydr)oxides and Fe(III) arsenates, thereby enhancing dissolved arsenic in the shallow groundwater at average concentration of 7.76 mg/L. In the organic-rich aggregates and wood particles, however, microbial sulfate reduction triggers the formation of realgar deposits, leading to accumulation of As in the distinct organic-rich patches of the shallow subsurface. We conclude that precipitation of realgar in the shallow subsurface of soil/sediment depends on specific and non-trivial combination of water and rock chemistry, microbial community composition and spatial organisation of the subsurface zone, where speciation in saturated environments varied on a centimeter scale from reduced (decomposed wood, H2S and realgar present) to oxidized (goethite and arsenate minerals are present).

  13. 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.

  14. 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.

  15. 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).

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. The Biological Nature of Geochemical Proxies: algal symbionts affect coral skeletal chemistry

    NASA Astrophysics Data System (ADS)

    Owens, K.; Cohen, A. L.; Shimizu, N.

    2001-12-01

    The strontium-calcium ratio (Sr/Ca) of reef coral skeleton is an important ocean temperature proxy that has been used to address some particularly controversial climate change issues. However, the paleothermometer has sometimes proven unreliable and there are indications that the temperature-dependence of Sr/Ca in coral aragonite is linked to the photosynthetic activity of algal symbionts (zooxanthellae) in coral tissue. We examined the effect of algal symbiosis on skeletal chemistry using Astrangia danae, a small colonial temperate scleractinian that occurs naturally with and without zooxanthellae. Live symbiotic (deep brown) and asymbiotic (white) colonies of similar size were collected in Woods Hole where water temperatures fluctuate seasonally between -2oC and 23oC. We used a microbeam technique (Secondary Ion Mass Spectrometry) and a 30 micron diameter sampling beam to construct high-resolution Sr/Ca profiles, 2500 microns long, down the growth axes of the outer calical (thecal) walls. Profiles generated from co-occuring symbiotic and asymbiotic colonies are remarkably different despite their exposure to identical water temperatures. Symbiotic coral Sr/Ca displays four large-amplitude annual cycles with high values in the winter, low values in the summer and a temperature dependence similar to that of tropical reef corals. By comparison, Sr/Ca profiles constructed from asymbiotic coral skeleton display little variability over the same time period. Asymbiont Sr/Ca is relatively insensitive to the enormous temperature changes experienced over the year; the temperature dependence is similar to that of nighttime skeletal deposits in tropical reef corals and non-biological aragonite precipitates. We propose that the large variations in skeletal Sr/Ca observed in all symbiont-hosting coral species are not related to SST variability per se but are driven primarily by large seasonal variations in skeletal calcification rate associated with symbiont photosynthesis. Our

  4. 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

  5. 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.

  6. Prevention of Marine Biofouling Using the Natural Allelopathic Compound Batatasin-III and Synthetic Analogues.

    PubMed

    Moodie, Lindon W K; Trepos, Rozenn; Cervin, Gunnar; Bråthen, Kari Anne; Lindgård, Bente; Reiersen, Rigmor; Cahill, Patrick; Pavia, Henrik; Hellio, Claire; Svenson, Johan

    2017-07-28

    The current study reports the first comprehensive evaluation of a class of allelopathic terrestrial natural products as antifoulants in a marine setting. To investigate the antifouling potential of the natural dihydrostilbene scaffold, a library of 22 synthetic dihydrostilbenes with varying substitution patterns, many of which occur naturally in terrestrial plants, were prepared and assessed for their antifouling capacity. The compounds were evaluated in an extensive screen against 16 fouling marine organisms. The dihydrostilbene scaffold was shown to possess powerful general antifouling effects against both marine microfoulers and macrofoulers with inhibitory activities at low concentrations. The species of microalgae examined displayed a particular sensitivity toward the evaluated compounds at low ng/mL concentrations. It was shown that several of the natural and synthetic compounds exerted their repelling activities via nontoxic and reversible mechanisms. The activities of the most active compounds such as 3,5-dimethoxybibenzyl (5), 3,4-dimethoxybibenzyl (9), and 3-hydroxy-3',4,5'-trimethoxybibenzyl (20) were comparable to the commercial antifouling booster biocide Sea-nine, which was employed as a positive control. The investigation of terrestrial allelopathic natural products to counter marine fouling represents a novel strategy for the design of "green" antifouling technologies, and these compounds offer a potential alternative to traditional biocidal antifoulants.

  7. 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

  8. 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.

  9. 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.

  10. 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

    2015-03-02

    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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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.

  12. Natural compounds of the strobilurin series and their synthetic analogues as cell respiration inhibitors

    NASA Astrophysics Data System (ADS)

    Zakharychev, Vladimir V.; Kovalenko, Leonid V.

    1998-06-01

    A group of fungicidal antibiotics, β-methoxyacrylic acid derivatives (strobilurins, oudemansins, and myxothiazols), their producers, and mechanisms of action are considered. The fungicidal activity of these compounds is based on the suppression of cell respiration of fungi in the bc1-complex of cytochromes. They also manifest other biological activities that are not always coupled with inhibition of respiration. Studies of the structure of the natural methoxyacrylates has made it possible to create a novel class of synthetic agricultural fungicides with enhanced stability, high activity, and a broad spectrum of action. The main regularities of the structure-activity relationship and methods of synthesis of these compounds are discussed. The bibliography includes 159 references.

  13. 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

  14. 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.

  15. Tracing the CO2 source and migration in natural analogues from different geological contexts

    NASA Astrophysics Data System (ADS)

    Battani, A.; Jean Luc, F.; Philippe, S.; Nadine, E.; Olivier, V.; Elodie, J.

    2009-12-01

    Naturally occurring CO2 fields allow studying long-term fluid-rock interactions, and the processes of CO2 migration, useful for the prediction of CO2 behavior in industrial storage sites. Two different provinces showing both leaking systems (hydrothermal areas) and well confined systems (stable sedimentary basins) have been studied. The first province concerns the French CO2 province of Massif Central (volcanic events, seismic activity, high geothermal gradient) and the stable Valence basin. The other study was devoted to the Basin and Range province, USA, with hydrothermal, high seismic and volcanic activity, a high geothermal gradient (Soda Springs; Idaho, Sevier basin), and the non-hydrothermal stable area of the Colorado plateau (Green River, San Rafael anticline and Springerville). The aim is to link the CO2 sources and its subsurface migration to the geological context. In hydrothermal areas, the mesured helium isotopic ratio (R/Ra) is high (close to the mantle ratio), while the CO2/3He ratios move dramatically towards crustal values. In this context, isotopic and elemental noble gas data show that the gas migrates very fast from depth. In more confined areas (natural CO2 fields), the CO2 shows a more important proportion of radiogenic gases (4He) (crustal helium isotopic ratios) and the associated CO2/3He ratios are in the MORB range, or “mantle derived”. We try to explain the apparent discrepancy between the CO2/3He and the R/Ra values in both areas. As a primary assumption, the source of CO2 could be localized in the extensional zones of high geothermal gradient with important seismicity. We suggest that the pseudotachylites formed by frictional melting associated with each seismic event supply an instantaneous crustal CO2.amount to the initial magmatic CO2. This justifies the coeval increase of the CO2/3He ratios without any significant modification in the helium isotopic ratios (instantaneous, no time for 4He production). Moreover, the contact

  16. Evidence of alkali rich melt reactions with mantle peridotite : Natural observations and experimental analogues

    NASA Astrophysics Data System (ADS)

    Grant, T. B.; Milke, R.; Wunder, B.

    2012-04-01

    The Heldburg Phonolite, (Thuringia, Germany) is peculiar in its nature due to its absence of a Eu anomaly, and hence lack of feldspar fractionation, as well as the presence of spinel lherzolite xenocrysts. These observations suggest a higher than normal (mantle) pressure of origin, and its potential as a metasomatic agent at depth is explored in this work. Disequilibrium between the phonolite and its entrained upper mantle xenocrysts resulted in the development of secondary reaction rim assemblages of; (1) phlogopite + minor diopside around olivine, (2) pargasitic amphibole, phlogopite and minor diopside around orthopyroxene. We document both the natural rims and the attempts to reproduce them under experimental conditions, in order to elucidate the likely origin of the phonolite and its efficacy for metasomatising the upper mantle. Platinum capsules were loaded with mixtures of crushed mineral separates, (of pure synthetic forsterite, San Carlos olivine, synthetic enstatite or a natural enstatite from Kilosa, Tanzania) with a synthetic Fe-free phonolite melt in a 16:84% weight ratio, respectively. Experiments were run in a piston cylinder apparatus with CaF2 as the pressure medium. In addition to varying PT conditions, a wide range of water contents were tested (0-14wt%). It was found that pressures of 10-14 kbar, and temperatures of 900-1000°C, satisfy the conditions at which the reactions can form, thus, it is likely that the phonolite existed at upper mantle conditions. Water must be present to stabilize the desired hydrous phases, with >6wt% required at 900°C and 10 kbar. The destabilization of feldspar is also essential to the process, hence higher water contents are needed at the lowest PT conditions compared to 4-5 wt. % H2O at greater PT. The formation of amphibole around enstatite appears to be affected by sluggish reaction kinetics and the orientation of the host pyroxene, sometimes leading to diopside single rims. Furthermore we note some of the

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

    PubMed

    Radtke, Christine

    2016-10-20

    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.

  18. 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

  19. Synthesis of D-lyxitol and D-ribitol analogues of the naturally occurring glycosidase inhibitor salacinol.

    PubMed

    Kumar, Nag S; Pinto, B Mario

    2005-12-12

    The synthesis of analogues of the naturally occurring glycosidase inhibitor, salacinol, in which the D-arabinitol ring has been replaced by D-lyxitol or D-ribitol, is described. Salacinol is one of the active principles in the aqueous extracts of Salacia reticulata, which are traditionally used in India and Sri Lanka for the treatment of Type II diabetes. The synthetic strategy relies on the nucleophilic attack of 1,4-anhydro-2,3,5-tri-O-p-methoxybenzyl-4-thio-D-lyxitol or 1,4-anhydro-2,3,5-tri-O-p-methoxybenzyl-4-thio-D-ribitol at the least hindered carbon of the benzylidene-protected L-cyclic sulfate derived from L-erythritol. Screening of these compounds against recombinant human maltase glucoamylase (MGA), a critical intestinal glucosidase involved in the processing of oligosaccharides of glucose into glucose itself, shows that they are not effective inhibitors of MGA and demonstrates the importance of the d-arabinitol configuration in the heterocyclic ring for effective inhibition.

  20. The Bengamides: A Mini-Review of Natural Sources, Analogues, Biological Properties, Biosynthetic Origins, and Future Prospects.

    PubMed

    White, Kimberly N; Tenney, Karen; Crews, Phillip

    2017-03-24

    This review focuses entirely on the natural bengamides and selected synthetic analogues that have inspired decades of research. Bengamide A was first reported in 1986 from the sponge Jaspis cf. coriacea, and bengamide-containing sponges have been gathered from many biogeographic sites. In 2005, a terrestrial Gram-negative bacterium, Myxococcus virescens, was added as a source for bengamides. Biological activity data using varying bengamide-based scaffolds has enabled fine-tuning of structure-activity relationships. Molecular target finding contributed to the creation of a synthetic "lead" compound, LAF389, that was the subject of a phase I anticancer clinical trial. Despite clinical trial termination, the bengamide compound class is still attracting worldwide attention. Future breakthroughs based on the bengamide scaffold are possible and could build on their nanomolar in vitro and positive in vivo antiproliferative and antiangiogenic properties. Bengamide molecular targets include methionine aminopeptidases (MetAP1 and MetAP2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). A mixed PKS/NRPS biosynthetic gene cluster appears to be responsible for creation of the bengamides. This review highlights that the bengamides have driven inspirational studies and that they will remain relevant for future research, even 30 years after the discovery of the first structures.

  1. The Bengamides: A Mini-Review of Natural Sources, Analogues, Biological Properties, Biosynthetic Origins, and Future Prospects

    PubMed Central

    2017-01-01

    This review focuses entirely on the natural bengamides and selected synthetic analogues that have inspired decades of research. Bengamide A was first reported in 1986 from the sponge Jaspis cf. coriacea, and bengamide-containing sponges have been gathered from many biogeographic sites. In 2005, a terrestrial Gram-negative bacterium, Myxococcus virescens, was added as a source for bengamides. Biological activity data using varying bengamide-based scaffolds has enabled fine-tuning of structure–activity relationships. Molecular target finding contributed to the creation of a synthetic “lead” compound, LAF389, that was the subject of a phase I anticancer clinical trial. Despite clinical trial termination, the bengamide compound class is still attracting worldwide attention. Future breakthroughs based on the bengamide scaffold are possible and could build on their nanomolar in vitro and positive in vivo antiproliferative and antiangiogenic properties. Bengamide molecular targets include methionine aminopeptidases (MetAP1 and MetAP2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). A mixed PKS/NRPS biosynthetic gene cluster appears to be responsible for creation of the bengamides. This review highlights that the bengamides have driven inspirational studies and that they will remain relevant for future research, even 30 years after the discovery of the first structures. PMID:28185457

  2. 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...

  3. 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...

  4. The Brattleboro Rat Displays a Natural Deficit in Social Discrimination that is Restored by Clozapine and a Neurotensin Analogue

    PubMed Central

    Feifel, D.; Mexal, S.; Melendez, G.; Liu, P. Y. T.; Goldenberg, J.; Shilling, P. D.

    2009-01-01

    Cognitive deficits in schizophrenia are a major source of dysfunction for which more effective treatments are needed. The vasopressin-deficient Brattleboro (BRAT) rat has been shown to have several natural schizophrenia-like deficits, including impairments in prepulse inhibition and memory. We investigated BRAT rats and their parental strain, Long Evans (LE) rats, in a social discrimination paradigm, which is an ethologically-relevant animal test of cognitive deficits of schizophrenia based upon the natural preference of animals to investigate conspecifics. We also investigated the effects of the atypical antipsychotic, clozapine and the putative antipsychotic, PD149163, a brain-penetrating neurotensin-1 analogue, on social discrimination in these rats. Adult rats were administered saline or one of three doses of clozapine (0.1, 1.0 or 10 mg/kg) or PD149163 (0.1, 0.3 or 1.0 mg/kg), subcutaneously. Following drug administration, adult rats were exposed to a juvenile rat for a 4-minute learning period. Animals were then housed individually for 30 minutes and then simultaneously exposed to the previously presented juvenile and a new juvenile for 4 minutes. Saline-treated LE rats, but not BRAT rats, exhibited intact social discrimination as evidenced by greater time spent exploring the new juvenile. The highest dose of clozapine and the two highest doses of PD149163 restored social discrimination in BRAT rats. These results provide further support for the utility of the BRAT rat as a genetic animal model relevant to schizophrenia and drug discovery. The potential of neurotensin agonists as putative treatments for cognitive deficits of schizophrenia was also supported. PMID:19322170

  5. 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.

  6. 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

  7. 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

  8. Geochemical constraints on the nature of magma sources for Triassic granitoids from South Qinling in central China

    NASA Astrophysics Data System (ADS)

    Lu, Ying-Hui; Zhao, Zi-Fu; Zheng, Yong-Fei

    2017-07-01

    A combined study of zircon U-Pb ages and Lu-Hf isotopes, whole-rock major-trace elements and Sr-Nd isotopes as well as mineral chemistry and O isotopes was carried out for Triassic granitoids from the South Qinling orogen in central China. Model calculations were also performed to examine the trace element fractionation during partial melting of crustal rocks. The results provide insights into the nature of magma sources for these granitoids. LA-ICPMS zircon U-Pb dating yields concordant ages of 208 ± 2 to 216 ± 3 Ma for these granitoids from the Shahewan (SHW), Caoping (CP) and Zhashui (ZS) plutons, and no relict zircon cores are identified by the CL imaging and U-Pb dating. The SHW and CP granitoids contain hornblende and are metaluminous with A/CNK ratios of 0.84 to 0.93. They exhibit relatively low SiO2 contents (62.88-69.04 wt.%) but high contents of FeOT, MgO and TiO2, and slightly to negligibly negative Eu anomalies (δEu = 0.79-0.89). Zircons from them show mantle-like δ18O values of 4.71 to 5.72‰. In contrast, the ZS granites contain no hornblende and are metaluminous to weakly peraluminous with A/CNK ratios of 0.99 to 1.03. They show relatively high SiO2 contents (69.32-75.94 wt.%) but low FeOT, MgO and TiO2 contents, and moderate negative Eu anomalies (δEu = 0.63-0.81). They have slightly low zircon δ18O values of 4.60 to 4.83‰. All of these granitoids show arc-like trace element distribution patterns with enrichment in LREE and LILE (e.g., Rb, K and Pb) but depletion in HFSE (e.g., Nb, Ta and Ti). Geochemical comparison and modeling indicate that these granitoids are different from adakitic rocks originating from the thickened lower continental crust. Compared with the composition of felsic melts produced by petrological experiments of various lithologies, it appears that these granitoids are derived from dehydration melting of metabasaltic sources at normal lower crustal depths, and experienced varying degrees of fractional crystallization

  9. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Studies on mimicry of naturally occurring annonaceous acetogenins: non-THF analogues leading to remarkable selective cytotoxicity against human tumor cells.

    PubMed

    Zeng, Bu-Bing; Wu, Yikang; Jiang, Sheng; Yu, Qian; Yao, Zhu-Jun; Liu, Zhong-Hai; Li, Hong-Yan; Li, Yan; Chen, Xiao-Guang; Wu, Yu-Lin

    2003-01-03

    A class of structurally simplified analogues of the naturally occurring annonaceous acetogenins were developed, amongst which some non-THF analogues showed remarkable cytotoxicities against tumor cell lines, as well as good selectivity between human tumor cells and normal cells. The synthetic routes were significantly shortened because of the removal of the chiral centers bearing the THF rings on the natural templates. This simplification also provides access to the parallel synthesis of these mimics by a combinatorial strategy. The remaining stereogenic centers at the positions alpha to the ethereal links were introduced by the Chiron approach from the easily accessible chiral building blocks 6a and/or 6b, made in turn from L-ascorbic acid or D-mannitol, while the one in the butenolide segment was taken from L-lactate. All four diastereomeric non-THF analogues 2a-2d showed remarkable activity against the HCT-8 cell line, and better differentiation was found when testing against the HT-29 cell line. It was also discovered that both the butenolide and ethylene glycol subunits play essential roles in the cytotoxicities against tumor cell lines, while the 10-substituted hydroxy group and the absolute configuration of methyl group at the butenolide moiety are less important for their activity.

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

    PubMed

    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.

  12. Lessons from Natural CO2 Leakage Analogue Site Studies and their Application to Secure CO2 Storage and Monitoring

    NASA Astrophysics Data System (ADS)

    Han, W.; McPherson, B. J.; Kim, K.; Chae, G.; Yum, B.

    2011-12-01

    At CO2 injection sites, CO2 leakage from the storage formation could be catastrophic. CO2 is a highly compressible fluid, typically injected at high pressure and temperature conditions. If this compressed CO2 reaches highly permeable conduits such as faults and fractures, CO2 could leak unabated to other formations (e.g. fresh water aquifers) and/or to the surface. Assuming a fast-flow path to the surface, CO2 escaping from the storage formation instantaneously reaches the surface while experiencing adiabatic expansion, which results in Joule-Thomson cooling. The addressed eruptive mechanisms are analogues to natural CO2 eruption mechanisms, which are found in CO2-driven cold-water geysers around the world. A notable example of a CO2-driven cold-water geyser is the Crystal Geyser in central Utah. The fluid mechanics of this regularly erupting geyser was investigated by instrumenting its conduit with pressure, temperature, pH, EC, and dissolved oxygen sensors, measuring every 1 minute during and between eruptions. Results of these measurements suggest that the time-scale of a single-eruption cycle is composed of four successive eruption types with two recharge periods ranging from 30 to 40 hours. Current eruption patterns exhibit a bimodal distribution although previous measurements and anecdotal evidence suggests that this pattern was different prior to recent seismic activity. This cold geyser's eruptions are regular and predictable, and reflect pressure, temperature, EC, pH, and dissolved oxygen changes resulting from Joule-Thomson cooling, endothermic CO2 exsolution, and exothermic CO2 dissolution. Specifically, the perturbation of pressure and temperature data observed at the Crystal Geyser suggested the possibility of using temperature sensing technology within the observation well at the engineered CO2 sequestration site. With the lessons learned from the Crystal Geyser studies, we established the theoretical framework of temperature changes caused by CO2

  13. Total Synthesis of Vinblastine, Related Natural Products, and Key Analogues and Development of Inspired Methodology Suitable for the Systematic Study of Their Structure–Function Properties

    PubMed Central

    2015-01-01

    Conspectus Biologically active natural products composed of fascinatingly complex structures are often regarded as not amenable to traditional systematic structure–function studies enlisted in medicinal chemistry for the optimization of their properties beyond what might be accomplished by semisynthetic modification. Herein, we summarize our recent studies on the Vinca alkaloids vinblastine and vincristine, often considered as prototypical members of such natural products, that not only inspired the development of powerful new synthetic methodology designed to expedite their total synthesis but have subsequently led to the discovery of several distinct classes of new, more potent, and previously inaccessible analogues. With use of the newly developed methodology and in addition to ongoing efforts to systematically define the importance of each embedded structural feature of vinblastine, two classes of analogues already have been discovered that enhance the potency of the natural products >10-fold. In one instance, remarkable progress has also been made on the refractory problem of reducing Pgp transport responsible for clinical resistance with a series of derivatives made accessible only using the newly developed synthetic methodology. Unlike the removal of vinblastine structural features or substituents, which typically has a detrimental impact, the additions of new structural features have been found that can enhance target tubulin binding affinity and functional activity while simultaneously disrupting Pgp binding, transport, and functional resistance. Already analogues are in hand that are deserving of full preclinical development, and it is a tribute to the advances in organic synthesis that they are readily accessible even on a natural product of a complexity once thought refractory to such an approach. PMID:25586069

  14. Analogue Gravity.

    PubMed

    Barceló, Carlos; Liberati, Stefano; Visser, Matt

    2011-01-01

    Analogue gravity is a research programme which investigates analogues of general relativistic gravitational fields within other physical systems, typically but not exclusively condensed matter systems, with the aim of gaining new insights into their corresponding problems. Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particularly simple example of an analogue model, before exploring the rich history and complex tapestry of models discussed in the literature. The last decade in particular has seen a remarkable and sustained development of analogue gravity ideas, leading to some hundreds of published articles, a workshop, two books, and this review article. Future prospects for the analogue gravity programme also look promising, both on the experimental front (where technology is rapidly advancing) and on the theoretical front (where variants of analogue models can be used as a springboard for radical attacks on the problem of quantum gravity).

  15. 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.

  16. 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.

  17. 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.

  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

    2001-01-08

    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. Extending the structure-activity relationship study of marine natural ningalin B analogues as P-glycoprotein inhibitors.

    PubMed

    Yang, Chao; Wong, Iris L K; Peng, Kai; Liu, Zhen; Wang, Peng; Jiang, Tingfu; Jiang, Tao; Chow, Larry M C; Wan, Sheng Biao

    2017-01-05

    In the present study, a total of 25 novel ningalin B analogues were synthesized and evaluated for their P-gp modulating activity in a P-gp overexpressed breast cancer cell line LCC6MDR. Preliminary structure-activity study shows that A ring and its two methoxy groups are important pharmacophores for P-gp inhibiting activity. Among all derivatives, 23 is the most potent P-gp modulator with EC50 of 120-165 nM in reversing paclitaxel, DOX, vinblastine and vincristine resistance. It is relatively safe to use with selective index at least greater than 606 compared to verapamil. Mechanistic study demonstrates that compound 23 reverses P-gp mediated drug resistance by inhibiting transport activity of P-gp, thereby restoring intracellular drug accumulation. In summary, our study demonstrates that ningalin B analogue 23 is a non-cytotoxic and effective P-gp chemosensitizer that can be used in the future for reversing P-gp mediated clinical cancer drug resistance.

  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. 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.

  4. 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.

  5. Estimation of the radiological background and dose assessment in areas with naturally occurring uranium geochemical anomalies--a case study in the Iberian Massif (Central Portugal).

    PubMed

    Pereira, A J S C; Neves, L J P F

    2012-10-01

    Naturally occurring uranium geochemical anomalies, representative of the several thousand recognized in the Portuguese section of the Iberian Massif and outcropping in three target areas with a total of a few thousand square metres, were subjected to a detailed study (1:1000 scale) to evaluate the radiological health-risk on the basis of a dose assessment. To reach this goal some radioactive isotopes from the uranium, thorium and potassium radioactive series were measured in 52 samples taken from different environmental compartments: soils, stream sediments, water, foodstuff (vegetables) and air; external radiation was also measured through a square grid of 10×10 m, with a total of 336 measurements. The results show that some radioisotopes have high activities in all the environmental compartments as well as a large variability, namely for those of the uranium decay chain, which is a common situation in the regional geological setting. Isotopic disequilibrium is also common and led to an enrichment of several isotopes in the different pathways, as is the case of (226)Ra; maximum values of 1.76 Bq L(-1) (water), 986 Bq kg(-1) (soils) and 18.9 Bq kg(-1) (in a turnip sample) were measured. On the basis of a realistic scenario combined with the experimental data, the effective dose from exposure to ionizing radiation for two groups of the population (rural and urban) was calculated; the effective dose is variable between 8.0 and 9.5 mSv year(-1), which is 3-4 times higher than the world average. Thus, the radiological health-risk for these populations could be significant and the studied uranium anomalies must be taken into account in the assessment of the geochemical background. The estimated effective dose can also be used as typical of the background of the Beiras uranium metalogenetic province and therefore as a "benchmark" in the remediation of the old uranium mining sites. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Asphalt Volcanism as a Model to Understand the Geochemical Nature of Pitch Lake, a Planetary Analog for Titan and the Implications towards Methane Flux into Earth's Atmosphere.

    NASA Astrophysics Data System (ADS)

    Khan, A.

    2016-12-01

    Pitch Lake is located in the southwest peninsula of the island near La Brea in Trinidad and Tobago, covering an area of approximately 46 hectares. It was discovered in the year 1595 and is the largest of three natural asphalt lakes that exist on Earth. Pitch Lake is a large oval shaped reservoir composed of dominantly hydrocarbon compounds, but also includes minor amounts of clay and muddy water. It is a natural liquid asphalt desert, which is nourished by a form of petroleum consisting of mostly asphaltines from the surrounding oil-rich region. The hydrocarbons mix with mud and gases under high pressure during upward seepage, and the lighter portion evaporates or is volatilized, which produces a high-viscosity liquid asphalt residue. The residue on and near the surface is a hydrocarbon matrix, which poses extremely challenging environmental conditions to microorganisms characterized by an average low water activity in the range of 0.49 to 0.75, recalcitrant carbon substrates, and toxic chemical compounds. Nevertheless, an active microbial community of archaea and bacteria, many of them novel strains, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical analyses of minerals, done by our team, which revealed sulfates, sulfides, silicates, and metals, normally associated with deep-water hydrothermal vents leads to our new hypothetical model to describe the origins of Pitch Lake and its importance to atmospheric and earth sciences. Pitch Lake is likely the terrestrial equivalent of an offshore submarine asphalt volcano just as La Brea Tar Pits are in some ways an on-land version of the asphalt volcanoes discovered off shore of Santa Barbara by Valentine et al. in 2010. Asphalt volcanism possibly also creates the habitat for chemosynthetic life that is widespread in this lake, as reported by Schulze-Makuch et al. in 2011 and Meckenstock et al. in 2014.

  11. Physical and geochemical drivers of CDOM variability near a natural seep site in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Edwards, C. R.; Powers, L.; Medeiros, P. M.

    2016-02-01

    Colored dissolved organic matter (CDOM) on the continental shelf and slope can serve as a marker for fresh water influence, indicate the presence of hydrocarbons, and provide important clues about nutrient content and organic matter cycling. Autonomous underwater vehicles such as gliders allow for subsurface measurement of CDOM fluorescence for weeks to months; these time series may be especially valuable in the northern Gulf of Mexico, where CDOM inputs of both terrestrial and oil and gas sources can be significant. Data from a recent glider deployment near a natural seep site (GC600) on the continental slope over 180km from shore suggest simultaneous influence of Mississippi plume water and hydrocarbon inputs in the upper 200m, with variability in fluorescence at a range of vertical and temporal scales. We will explore patterns in spatial and temporal variability of glider-measured hydrography, dissolved oxygen, and bio-optical data (CDOM, chlorophyll-a, backscatter fluorescence), and use their combination to infer a terrigenous and/or fossil fuel source(s). Taking advantage of a combination of satellite sea surface temperature, ocean color, wind, and data from moored and mobile platforms, we will examine physical controls on transport and vertical mixing of CDOM and the potential role of nonlinear mesoscale eddies, which can trap water in their interior and may transport river- or hydrocarbon-derived CDOM over long distances. The combined data set will be used to consider and potentially constrain the effect of photodegradation and other biogeochemical causes for CDOM fluorescence variability in the upper 200m.

  12. 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.

  13. 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 .

  14. Spectroscopic Investigation of Peridinin Analogues having Different π-electron Conjugated Chain Lengths: Exploring the Nature of the Intramolecular Charge Transfer State

    PubMed Central

    Niedzwiedzki, Dariusz M.; Chatterjee, Nirmalya; Enriquez, Miriam M.; Kajikawa, Takayuki; Hasegawa, Shinji; Katsumura, Shigeo; Frank, Harry A.

    2009-01-01

    The lifetime of the lowest excited singlet (S1) state of peridinin and many other carbonyl-containing carotenoids and polyenes has been reported depend on the polarity of the solvent. This effect has been attributed to the presence of an intramolecular charge transfer (ICT) state in the manifold of excited states for these molecules. The nature of this ICT state has yet to be elucidated. In the present work, steady-state and ultrafast time-resolved optical spectroscopy have been performed on peridinin and three synthetic analogues, C33-peridinin, C35-peridinin, and C39-peridinin which have different numbers of conjugated carbon-carbon double bonds. Otherwise, the molecules are structurally similar in that they posses the same functional groups. The trends in the positions of the steady-state and transient spectral profiles for this systematic series of molecules allow an assignment of the spectral features to transitions involving the S0, S1, S2 and ICT states. A kinetics analysis reveals the lifetimes of the excited states and the dynamics of their excited state deactivation pathways. The most striking observation in the data is that the lifetime of the ICT state converges to the same value of 10.0 ± 2.0 ps in the polar solvent, methanol, for all the peridinin analogues regardless of the extent of π-electron conjugation. This suggests that the ICT state is highly localized on the lactone ring which is a common structural feature in all the molecules. The data further suggest that the S1 and ICT states behave independently and that the ICT state is populated both from both S1 and S2, the rate and efficiency from S1 being dependent on the length of the π-electron chain of the carotenoid and the solvent polarity. PMID:19775150

  15. X-ray absorption fine-structure spectroscopy studies of Fe sites in natural human neuromelanin and synthetic analogues.

    PubMed Central

    Kropf, A J; Bunker, B A; Eisner, M; Moss, S C; Zecca, L; Stroppolo, A; Crippa, P R

    1998-01-01

    X-ray absorption fine-structure spectroscopy is used to study the local environment of the iron site in natural (human) neuromelanin extracted from substantia nigra tissue and in various synthetic neuromelanins. All the materials show Fe centered in a nearest neighbor sixfold (distorted) oxygen octahedron; the Fe-O distances, while slightly different in the natural and synthetic neuromelanin, are both approximately 2.0 A. Appreciable differences arise, however, in the second (and higher) coordination shells. In this case the synthetic melanin has the four planar oxygens bound to carbon rings with Fe-C distances of approximately 2.82 and 4.13 A; the human sample does not show the 2.82 A link but instead indicates a double shell at approximately 3.45 and 3.78 A. PMID:9826634

  16. Synthesis of psymberin analogues: probing a functional correlation with the pederin/mycalamide family of natural products.

    PubMed

    Jiang, Xin; Williams, Noelle; De Brabander, Jef K

    2007-01-18

    In this letter we describe an efficient synthesis of "psympederin", a hybrid between the novel antitumor natural product psymberin and the blister beetle toxin pederin. Evaluation of antiproliferative activity reveals that the dihydroisocoumarin fragment is important for psymberin toxicity and the cyclic pederate fragment is important for pederin/mycalamide toxicity. On the basis of preliminary results described herein, we speculate that, despite their structural resemblance, psymberin and pederin/mycalamide induce toxicity through different mechanisms. [reaction: see text].

  17. 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.

  18. 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

  19. Synthesis of withasomnines and their non-natural analogues from aldehydes and 4-nitro-1-butanol in three steps.

    PubMed

    Verma, Deepti; Kumar, Rahul; Namboothiri, Irishi N N

    2013-04-05

    Total synthesis of all three pyrazole-based withasomnine alkaloids and selected examples of their non-natural analogs has been achieved from readily available aldehydes and 4-nitro-1-butanol in three steps. Since 4-nitro-1-butanol in turn is prepared in two steps via Michael addition of nitromethane to acrylate followed by borane reduction of the ester group and the key 1,3-dipolar cycloaddition step is carried out with commercially available TMSCHN2, this approach is a very convenient and economical one.

  20. 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 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.

  2. 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

  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. 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.

  5. 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 ...

  6. 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 ...

  7. 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.

  8. A hydrological and geochemical analysis of chromium mobilization from serpentinized ultramafic rocks and serpentine soils at the McLaughlin Natural Reserve, Lake County, California

    NASA Astrophysics Data System (ADS)

    McClain, C.; Maher, K.; Fendorf, S.

    2011-12-01

    (VI) concentrations vary from < 2.5-22 μg/L, where the highest concentrations were found in seeps emanating from fractured serpentinite and in tributaries to Hunting Creek. Aqueous Cr is mostly present as Cr(VI) (likely CrO42- and MgCrO4), which is consistent with the high pH (7.98-8.72). A reactive transport approach, constrained by solid and fluid data, was used to assess the geochemical transformations that occur along flow paths in order to evaluate the coupling between hydrologic and biogeochemical processes. Similar ultramafic rocks and terrains occur in belts along the Coast Range and the Foothills to the Sierra Nevada and in the Klamath Mountains. Creeks and rivers draining these ultramafic terrains have transported Cr-bearing sediments to the Central Valley, (and other densely populated sedimentary basins and alluvial plains) where they are now widely distributed both at the surface and buried underground, interlaced with aquifer materials. This study highlights the importance of using a holistic approach that considers multiple length scales to understand the factors that control Cr distribution and speciation in natural waters.

  9. 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

  10. Epinephrine analogues.

    PubMed

    Sneader, W

    2001-11-01

    Tyramine was the first epinephrine analogue to be introduced into medicine, in the early 1900s. It was followed by ephedrine and pseudoephedrine in the 1920s and by the amfetamines a decade later. The popularity of the amfetamines grew throughout the 1930s and 1940s; after that, there was a slowly dawning realization that they were being widely abused. Isoprenaline, introduced in the 1950s, was soon recognized as superior to epinephrine when used as an inhaler by asthmatics, and it remained the drug of choice for the relief of bronchospasm until around 1970. Orciprenaline, which featured an orcinol system, had a long duration of action and was active by mouth; Boehringer marketed it both as an inhaler and as a syrup for the prophylaxis of bronchospasm. The greatly superior bronchodilators salbutamol and terbutaline, launched in 1968 and 1970, respectively, incorporate further variation on the molecular theme that had led to the development of orciprenaline. (c) 2001 Prous Science. All rights reserved.

  11. Long-term effects of CO2 on the mechanical behaviour of faults - a study of samples from a natural CO2 analogue (Entrada Sandstone, Utah, USA)

    NASA Astrophysics Data System (ADS)

    Hangx, S. J. T.; Bakker, E.; Spiers, C. J.

    2012-04-01

    In an attempt to reduce CO2 emissions, CO2 capture and storage in depleted oil and gas reservoirs is seen as one of the most important mitigation strategies. However, in order to achieve safe storage on geological timescales, it is key to maintain integrity of the caprock and any faults penetrating the seal. One of the largest uncertainties lies in the prediction of the effects of fluid-rock interaction on the mechanical integrity and sealing capacity of the reservoir-seal system in the very long term, i.e. on timescales of the order of 103 or 104 years. As chemical interactions in the rock/CO2/brine system are slow, their long-term effects on rock composition, microstructure, mechanical properties and transport properties cannot be properly reproduced in laboratory experiments. One way of addressing this issue is to conduct experiments on reservoir, caprock and fault rock samples taken from natural CO2 reservoir-seal systems, which can serve as natural analogues for CO2 storage fields. The transport and mechanical properties of these rock samples, which have reacted with CO2 over geological timescales, can then be compared with data obtained for laterally equivalent materials that are unaffected by CO2. The observed changes in rock properties can subsequently be used as input for numerical models aimed at assessing the long-term effects of CO2 on reservoir compaction, caprock damage, fault reactivation and fault permeability. We assessed the mechanical behaviour and transport properties of fault rocks. To this end, we performed triaxial direct shear experiments at room temperature under nominally dry conditions, at normal stresses up to 90 MPa and shear velocities of 0.22 -10.9 μm/s. Simulated fault rocks were prepared by crushing material obtained from surface outcrops of the Entrada Sandstone, one of the CO2-bearing formations from an analogue field under the Colorado Plateau, Utah, USA. Three types of starting material were obtained: 1) red-coloured samples

  12. 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.

  13. Geochemical and Sr-Nd isotope evidences of the suprasubduction nature of mesozoic magmatism in the Mongol-Okhotsk Sector of the Pacific Fold Belt

    NASA Astrophysics Data System (ADS)

    Derbeko, I. M.; Chugaev, A. V.; Oleinikova, T. I.; Bortnikov, N. S.

    2016-02-01

    In this article we present geochemical and isotope characteristics of rocks of the Unerikan, Selitkan and Aezop-Yamalin volcano-plutonic zones of the eastern termination of the Mongol-Okhotsk Orogenic Belt. The obtained data demonstrate that the Mesozoic igneous rocks of the Mongol-Okhotsk sector of the Pacific Folded Belt were formed due to the melting of the continental crust in a tectonic setting corresponding to a suprasubduction one.

  14. A combined modelling and geochemical study of the fate of terrigenous inputs from mixed natural and mining sources in a coral reef lagoon (New Caledonia).

    PubMed

    Fernandez, Jean-Michel; Ouillon, Sylvain; Chevillon, Christophe; Douillet, Pascal; Fichez, Renaud; Le Gendre, Romain

    2006-03-01

    Open-cast mining for Ni, Cr and Co was conducted in the south-west part of New Caledonia during the 20th century. Abandoned mining and prospecting sites were severely affected by erosion, resulting in an increase in the load of terrigenous particles transported to the coral reef lagoon. This article assesses the impact of a typical small catchment area (La Coulée River, 85 km2 watershed) on two bays (Boulari and Sainte Marie) located near Noumea, New Caledonia's main city. This multi-disciplinary study combines geochemical, sedimentological, and hydrodynamic approaches. Ni and Cr concentrations contained in the geochemical matrix phase of the pelitic fraction were determined. The study of the geochemical signatures together with sedimentological data and 3D numerical simulations of the transport of non-settling particles throughout the lagoon demonstrated that terrigenous inputs from the Coulée River were mainly transported and deposited along the shoreline, reaching areas as distant as Sainte Marie Bay. Although quantitatively low (about 3% of the pelite mass of the bay sediments), the terrigenous inputs in Sainte Marie Bay originating from the Coulée River could be traced. The metal content in suspended matter was over 7000 mg kg(-1) for Ni and 4200 mg kg(-1) for Cr.

  15. Activation of the Nuclear Factor E2-Related Factor 2 Pathway by Novel Natural Products Halomadurones A–D and a Synthetic Analogue

    PubMed Central

    Wyche, Thomas P.; Standiford, Miranda; Hou, Yanpeng; Braun, Doug; Johnson, Delinda A.; Johnson, Jeffrey A.; Bugni, Tim S.

    2013-01-01

    Two novel chlorinated pyrones, halomadurones A and B, and two novel brominated analogues, halomadurones C and D, were isolated from a marine Actinomadura sp. cultivated from the ascidian Ecteinascidia turbinata. Additionally, a non-halogenated analogue, 2-methyl-6-((E)-3-methyl-1,3-hexadiene)-γ-pyrone, was synthesized to understand the role of the halogens for activity. Halomadurones C and D demonstrated potent nuclear factor E2-related factor antioxidant response element (Nrf2-ARE) activation, which is an important therapeutic approach for treatment of neurodegenerative diseases. PMID:24351907

  16. 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).

  17. Investigation of natural and anthropogenic hydrocarbon inputs in sediments using geochemical markers. II. Sao Sebastião, SP--Brazil.

    PubMed

    Medeiros, Patricia Matheus; Bícego, Márcia Caruso

    2004-12-01

    The São Sebastião Channel, NE São Paulo State, Brazil, is an area of environmental interest of that state not only because of the tourism, but also because of the presence of the most important oil terminal of Brazil, the PETROBRAS Maritime Terminal (DTCS). Sediment samples were collected at 15 sites in the channel, extracted and analyzed by GC/FID and GC/MS for composition and levels of the following organic geochemical markers: aliphatic hydrocarbons (normal and isoprenoid alkanes), petroleum biomarkers, linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs). The total concentrations varied from 0.04 to 8.53 micorg g(-1) for aliphatics, from 51.1 to 422.0 ng g(-1) for petroleum biomarkers, from 12.6 to 27.7 ng g(-1) for LABs and from 20.4 to 200.3 ng g(-1) for PAHs. The PETROBRAS Maritime Terminal (DTCS), Sao Sebastião Harbor and sewage outfalls along the area had clear influences on the geochemical marker concentrations, especially at locales in the central and north parts of the channel.

  18. 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.

  19. 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

    2016-09-03

    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.

  20. 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

  1. Analogue VLSI for probabilistic networks and spike-time computation.

    PubMed

    Murray, A

    2001-02-01

    The history and some of the methods of analogue neural VLSI are described. The strengths of analogue techniques are described, along with residual problems to be solved. The nature of hardware-friendly and hardware-appropriate algorithms is reviewed and suggestions are offered as to where analogue neural VLSI's future lies.

  2. 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.

  3. Characterizing the Influence of Flow Regime and Landcover on the Geochemical Nature and Magnitude of Riverine Phosphorus and Trace Metal Loads

    NASA Astrophysics Data System (ADS)

    Rosenberg, B.; Schroth, A. W.

    2014-12-01

    Within aquatic systems, phosphorus (P) is a common limiting nutrient present in low bioavailable concentrations. Colloidal and particulate phases of the trace metals manganese (Mn) and iron (Fe) are common scavengers of phosphate in the freshwater environment, and the distribution and stability of such phases is thought to influence the bioavailability of P. The partitioning and flux of P and TM in rivers can be driven by the geochemical source of these constituents, as well as the hydrologic/biogeochemical pathways active within the watershed, both of which vary based on hydrologic condition and landcover. This study investigates how different landcovers (suburban, agricultural, forested, glacial) contribute to P and TM flux and partitioning during high-flow events (snowmelt, glacial melt, storms). High-resolution water and suspended sediment sampling was conducted during snowmelt in Vermont, as well as during summer storms and baseflow conditions. In Alaska, samples were collected during baseflow, glacial melt, and storm events to provide additional data from other landcovers and hydrologic systems. Initial analyses suggest that the size fraction, loading, and relative lability of water and suspended sediment pools of TM and P are strongly influenced by both land cover and seasonality/hydrology. Samples collected during snowmelt in VT show high concentrations of dissolved and potentially bioavailable particulate P at the start of melt that decrease over time. Coupled with high discharge events, a substantial load of labile P is delivered during this particular high flow period. As snowmelt transitions to baseflow conditions, with intermittent storms the character of the suspended sediment changes drastically, with lower total concentrations of P and TM as well as a lower proportion of extractable P (bound to easily reduced oxyhydroxides) to total sediment P. This study highlights that the snowmelt period is not only important from an overall all load standpoint

  4. The mechanism of phosphorylation of natural nucleosides and anti-HIV analogues by nucleoside diphosphate kinase is independent of their sugar substituents.

    PubMed

    Hutter, Michael C; Helms, Volkhard

    2002-07-02

    The reaction mechanism of the phosphoryl transfer catalyzed by dinucleoside diphosphate kinase from Dictyostelium discoideum is investigated by semiempirical AM1 molecular orbital computation of an active site model system on the basis of various X-ray crystallographic structures. The computational results suggest that the phosphoryl transfer from adenosine triphosphate to the His122 residue is accompanied by the simultaneous shift of a proton from the histidine residue to one of the oxygen atoms of the gamma phosphate group. This involves a doubly protonated His122 residue whilst this residue is neutral in its ternary complex with ADP and the transition state analogue AlF(3). The proposed mechanism is thus analogous to that of phosphoryl transfer by cyclic adenosine monophosphate dependent protein kinase and uridine/cytidine monophosphate kinase as found in our earlier work and clarifies the role of the ribose 3'-OH group. Furthermore, the energetics of phosphoryl transfer onto other nucleoside analogues such as 3'-azido-3'-deoxythymidine-diphosphate and 2',3'-dideoxy-2',3'-didehydro-thymidine-diphosphate are investigated. The calculated reaction barriers for the phosphorylation of the diphosphates by the enzyme are all within a range of 13.1 kJ mol(-1), which suggests that variations in the activation energies alone cannot account for the experimentally observed differences in enzymatic activity. Consequences for the design of new anti-HIV nucleoside analogues are discussed. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2268/2002/f360_s.pdf or from the author.

  5. 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

  6. Distinguishing the Source of Natural Gas Accumulations with a Combined Gas and Co-produced Formation Water Geochemical Approach: a Case Study from the Appalachian Basin

    EPA Pesticide Factsheets

    The purpose of this study is to discuss the use of gas and co-produced formation water geochemistry for identifying the source of natural gas and present gas geochemistry for the northern Appalachian Basin.

  7. Substituted trans-stilbenes, including analogues of the natural product resveratrol, inhibit the human tumor necrosis factor alpha-induced activation of transcription factor nuclear factor kappaB.

    PubMed

    Heynekamp, Justin J; Weber, Waylon M; Hunsaker, Lucy A; Gonzales, Amanda M; Orlando, Robert A; Deck, Lorraine M; Jagt, David L Vander

    2006-11-30

    The transcription factor nuclear factor kappaB (NF-kappaB), which regulates expression of numerous antiinflammatory genes as well as genes that promote development of the prosurvival, antiapoptotic state is up-regulated in many cancer cells. The natural product resveratrol, a polyphenolic trans-stilbene, has numerous biological activities and is a known inhibitor of activation of NF-kappaB, which may account for some of its biological activities. Resveratrol exhibits activity against a wide variety of cancer cells and has demonstrated activity as a cancer chemopreventive against all stages, i.e., initiation, promotion, and progression. The biological activities of resveratrol are often ascribed to its antioxidant activity. Both antioxidant activity and biological activities of analogues of resveratrol depend upon the number and location of the hydroxy groups. In the present study, phenolic analogues of resveratrol and a series of substituted trans-stilbenes without hydroxy groups were compared with resveratrol for their abilities to inhibit the human tumor necrosis factor alpha-induced (TNF-alpha) activation of NF-kappaB, using the Panomics NF-kappaB stable reporter cell line 293/NF-kappaB-luc. A series of 75 compounds was screened to identify substituted trans-stilbenes that were more active than resveratrol. Dose-response studies of the most active compounds were carried out to obtain IC50 values. Numerous compounds were identified that were more active than resveratrol, including compounds that were devoid of hydroxy groups and were 100-fold more potent than resveratrol. The substituted trans-stilbenes that were potent inhibitors of the activation of NFkappaB generally did not exhibit antioxidant activity. The results from screening were confirmed using BV-2 microglial cells where resveratrol and analogues were shown to inhibit LPS-induced COX-2 expression.

  8. Ecstasy analogues found in cacti.

    PubMed

    Bruhn, Jan G; El-Seedi, Hesham R; Stephanson, Nikolai; Beck, Olof; Shulgin, Alexander T

    2008-06-01

    Human interest in psychoactive phenethylamines is known from the use of mescaline-containing cacti and designer drugs such as Ecstasy. From the alkaloid composition of cacti we hypothesized that substances resembling Ecstasy might occur naturally. In this article we show that lophophine, homopiperonylamine and lobivine are new minor constituents of two cactus species, Lophophora williamsii (peyote) and Trichocereus pachanoi (San Pedro). This is the first report of putatively psychoactive phenethylamines besides mescaline in these cacti. A search for further biosynthetic analogues may provide new insights into the structure-activity relationships of mescaline. An intriguing question is whether the new natural compounds can be called "designer drugs."

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Energy-constrained open-system magmatic processes IV: Geochemical, thermal and mass consequences of energy-constrained recharge, assimilation and fractional crystallization (EC-RAFC)

    SciTech Connect

    Wendy A. Bohrson Department of Geological Sciences, Central Washington University, Ellensburg, Washington, 98926, USA; Frank J. Spera Institute for Crustal Studies and Department of Geological Sciences, University of California, Santa Barbara, California, 93106, USA

    2003-07-01

    A wealth of geochemical and petrological data provide evidence that the processes of fractional crystallization, assimilation, and magma recharge (replenishment) dominate the chemical signatures of many terrestrial igneous rocks. Previous work [ Spera and Bohrson, 2001 ; Bohrson and Spera, 2001 ] has established the importance of integrating energy, species and mass conservation into simulations of complex magma chamber processes. An extended version of the energy-constrained formulation, Energy-Constrained Recharge, Assimilation, Fractional Crystallization (EC-RAFC), tracks mass and compositional variations of melt, cumulates, and enclaves in a magma body undergoing simultaneous recharge, assimilation, and fractional crystallization [ Spera and Bohrson, 2002 ]. Because many EC-RAFC results are distinct from those predicted by extant RAFC formulations, the primary goal of this paper is to present a range of geochemical and mass relationships for selected cases that highlight issues relevant to modern petrology. Among the plethora of petrologic problems that have important, well-documented analogues in nature are the geochemical distinctions that arise when a magma body undergoes continuous versus episodic recharge, the connection between erupted magmas and associated cumulate bodies, the behavior of recharge-fractionation dominated systems (RFC), thermodynamic conditions that promote the formation of enclaves versus cumulates, and the conditions under which magma bodies may be described as chemically homogeneous. Investigation of the effects of continuous versus episodic recharge for mafic magma undergoing RAFC in the lower crust indicates that the resulting geochemical trends for melt and solids are sensitive to the intensity and composition of recharge, suggesting that EC-RAFC may be used as a tool to distinguish the nature of the recharge events. Compared to the record preserved in melts, the geochemical and mass characteristics of solids associated with

  14. Energy-constrained open-system magmatic processes IV: Geochemical, thermal and mass consequences of energy-constrained recharge, assimilation and fractional crystallization (EC-RAFC)

    NASA Astrophysics Data System (ADS)

    Bohrson, Wendy A.; Spera, Frank J.

    2003-02-01

    A wealth of geochemical and petrological data provide evidence that the processes of fractional crystallization, assimilation, and magma recharge (replenishment) dominate the chemical signatures of many terrestrial igneous rocks. Previous work [Spera and Bohrson, 2001; Bohrson and Spera, 2001] has established the importance of integrating energy, species and mass conservation into simulations of complex magma chamber processes. An extended version of the energy-constrained formulation, Energy-Constrained Recharge, Assimilation, Fractional Crystallization (EC-RAFC), tracks mass and compositional variations of melt, cumulates, and enclaves in a magma body undergoing simultaneous recharge, assimilation, and fractional crystallization [Spera and Bohrson, 2002]. Because many EC-RAFC results are distinct from those predicted by extant RAFC formulations, the primary goal of this paper is to present a range of geochemical and mass relationships for selected cases that highlight issues relevant to modern petrology. Among the plethora of petrologic problems that have important, well-documented analogues in nature are the geochemical distinctions that arise when a magma body undergoes continuous versus episodic recharge, the connection between erupted magmas and associated cumulate bodies, the behavior of recharge-fractionation dominated systems (RFC), thermodynamic conditions that promote the formation of enclaves versus cumulates, and the conditions under which magma bodies may be described as chemically homogeneous. Investigation of the effects of continuous versus episodic recharge for mafic magma undergoing RAFC in the lower crust indicates that the resulting geochemical trends for melt and solids are sensitive to the intensity and composition of recharge, suggesting that EC-RAFC may be used as a tool to distinguish the nature of the recharge events. Compared to the record preserved in melts, the geochemical and mass characteristics of solids associated with particular

  15. NMR structure determination of a synthetic analogue of bacillomycin Lc reveals the strategic role of L-Asn1 in the natural iturinic antibiotics

    NASA Astrophysics Data System (ADS)

    Volpon, Laurent; Tsan, Pascale; Majer, Zsuzsa; Vass, Elemer; Hollósi, Miklós; Noguéra, Valérie; Lancelin, Jean-Marc; Besson, Françoise

    2007-08-01

    Iturins are a group of antifungal produced by Bacillus subtilis. All are cyclic lipopeptides with seven α-amino acids of configuration LDDLLDL and one β-amino fatty acid. The bacillomycin L is a member of this family and its NMR structure was previously resolved using the sequence Asp-Tyr-Asn-Ser-Gln-Ser-Thr. In this work, we carefully examined the NMR spectra of this compound and detected an error in the sequence. In fact, Asp1 and Gln5 need to be changed into Asn1 and Glu5, which therefore makes it identical to bacillomycin Lc. As a consequence, it now appears that all iturinic peptides with antibiotic activity share the common β-amino fatty acid 8- L-Asn1- D-Tyr2- D-Asn3 sequence. To better understand the conformational influence of the acidic residue L-Asp1, present, for example in the inactive iturin C, the NMR structure of the synthetic analogue SCP [cyclo ( L-Asp1- D-Tyr2- D-Asn3- L-Ser4- L-Gln5- D-Ser6- L-Thr7-β-Ala8)] was determined and compared with bacillomycin Lc recalculated with the corrected sequence. In both cases, the conformers obtained were separated into two families of similar energy which essentially differ in the number and type of turns. A detailed analysis of both cyclopeptide structures is presented here. In addition, CD and FTIR spectra were performed and confirmed the conformational differences observed by NMR between both cyclopeptides.

  16. 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

  17. 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

  18. Geochemical and isotopic evidences from groundwater and surface water for understanding of natural contamination in chronic kidney disease of unknown etiology (CKDu) endemic zones in Sri Lanka.

    PubMed

    Edirisinghe, E A N V; Manthrithilake, H; Pitawala, H M T G A; Dharmagunawardhane, H A; Wijayawardane, R L

    2017-09-26

    Chronic kidney disease of unknown etiology (CKDu) is the main health issue in the dry zone of Sri Lanka. Despite many studies carried out, causative factors have not been identified yet clearly. According to the multidisciplinary researches carried out so far, potable water is considered as the main causative factor for CKDu. Hence, the present study was carried out with combined isotopic and chemical methods to understand possible relationships between groundwater; the main drinking water source, and CKDu in four endemic areas in the dry zone. Different water sources were evaluated isotopically ((2)H, (3)H and (18)O) and chemically from 2013 to 2015. Results revealed that prevalence of CKDu is significantly low with the groundwater replenished by surface water inputs. It is significantly high with the groundwater stagnated as well as groundwater recharged from regional flow paths. Thus, the origin, recharge mechanism and flow pattern of groundwater, as well as geological conditions which would be responsible for natural contamination of groundwater appear as the main causative factors for CKDu. Therefore, detailed investigations should be made in order to identify the element(s) in groundwater contributing to CKDu. The study recommends providing drinking water to the affected zones using water sources associated with surface waters.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. Template polymerization of nucleotide analogues

    NASA Technical Reports Server (NTRS)

    Orgel, L. E.

    1991-01-01

    Recent work on the template-directed reactions of the natural D-nucleotides has made it clear that l-nucleotides and nucleotide-like derivatives of other sugars would strongly inhibit the formation of long oligonucleotides. Consequently, attention is focusing on molecules simpler than nucleotides that might have acted as monomers of an information transfer system. We have begun a general exploration of the template directed reactions of diverse peptide analogues. I will present work by Dr. Taifeng Wu on oxidative oligomerization of phosphorothioates and of Dr. Mary Tohidi on the cyclic polymerization of nucleoside and related cyclic pyrophosphates.

  4. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  6. Nature, timing, and origin of wet climatic periods in Arabia from geochemical (stable isotopes, noble gas thermometry, geochronology) an geomorphological data

    NASA Astrophysics Data System (ADS)

    Emil, M. K.; Sultan, M.; Alharbi, T.; Albassam, A. M.; Chouinard, K.; Abuabdullah, M. M.

    2016-12-01

    An integrated approach was conducted to address the source(s), nature and timing of the wet periods in the Arabian Peninsula (AP) and in northern Africa by 1) comparing the isotopic composition of fossil groundwater to that of modern precipitation, (2) extracting recharge temperatures using noble gas concentrations, (3) Cl-36 age dating of fossil groundwater, and (4) investigating the spatial relationships between morphometric indexes (drainage density, etc.) of Cenozoic volcanic fields and paleo rainfall intensity. Groundwater samples (23) were collected from wells tapping alluvial aquifers along the Red Sea coastal plain, and from the Mega Aquifer System (upper Saq, Wajid and lower Minjur, Wasia-Biyadh, Umm Ar Radhuma formations). Findings include: (1) isotopic composition of modern precipitation over recharge areas (IAEA: δ2H: -2.18 ‰, δ18O: -1.66 ‰) is similar to that of coastal plain aquifers (δ2H: -0.9 to 0.7 ‰, δ18O: -1.47 to -0.85 ‰), but is enriched compared to fossil groundwater downgradient from recharge areas; (2) isotopic composition of fossil groundwater are progressively depleted eastwards along groundwater flow direction (δ2H; Saq:-13.2,-38.8‰, Wajid; -27.1,-42.6, -55.2‰, Minjur: -3.4, -28.1, -35.5, -35.4‰); (3) deeper Saq and Wajid aquifers exhibit isotopic compositions (d2H: -13.2 to -64.1 ‰) similar to those of the Sinai Nubian aquifer (δ2H: -18.7 to -72.9 ‰) suggesting a similar moisture source; (4) the younger Minjur, Wasia-Biyadh and Umm Ar Radhuma aquifers show less depleted compositions (δ2H: -3.4 to -35.4 ‰) and higher deuterium excess values (d-excess; 3.58 to 16.6 ‰) compared to deeper aquifers probably indicating mixing with recent meteoric precipitation and a Mediterranean moisture source; (5) Noble Gas Thermometry (NGT) for fossil aquifers provide cooler (2-6 °C) recharge temperatures compared to the Mean Annual Air Temperatures; (6) Chlorine-36 groundwater ages range from 140ka to 1000ka; (7) drainage

  7. Antimalarial Properties of Simplified Kalihinol Analogues.

    PubMed

    Daub, Mary Elisabeth; Prudhomme, Jacques; Ben Mamoun, Choukri; Le Roch, Karine G; Vanderwal, Christopher D

    2017-03-09

    Several kalihinol natural products, members of the broader isocyanoterpene family of antimalarial agents, are potent inhibitors of Plasmodium falciparum, the agent of the most severe form of human malaria. Our previous total synthesis of kalihinol B provided a blueprint to generate many analogues within this family, some as complex as the natural product and some much simplified and easier to access. Each analogue was tested for blood-stage antimalarial activity using both drug-sensitive and -resistant P. falciparum strains. Many considerably simpler analogues of the kalihinols retained potent activity, as did a compound with a different decalin scaffold made in only three steps from sclareolide. Finally, one representative compound showed reasonable stability toward microsomal metabolism, suggesting that the isonitrile functional group that is critical for activity is not an inherent liability in these compounds.

  8. 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.

  9. Synthesis of Natural O-Linked Carba-Disaccharides, (+)- and (−)-Pericosine E, and Their Analogues as α-Glucosidase Inhibitors

    PubMed Central

    Usami, Yoshihide; Mizuki, Koji; Kawahata, Rikiya; Shibano, Makio; Sekine, Atsuko; Yoneyama, Hiroki; Harusawa, Shinya

    2017-01-01

    Pericosine E (6), a metabolite of Periconia byssoides OUPS-N133 was originally isolated from the sea hare Aplysia kurodai, which exists as an enantiomeric mixture in nature. The enantiospecific syntheses of both enantiomers of Periconia byssoides OUPS-N133 has been achieved, along with six stereoisomers, using a common simple synthetic strategy. For these efficient syntheses, highly regio- and steroselective processes for the preparation of bromohydrin and anti-epoxide intermediates were applied. In order to access the unique O-linked carbadisaccharide structure, coupling of chlorohydrin as a donor and anti-epoxide as an acceptor was achieved using catalytic BF3·Et2O. Most of the synthesized compounds exhibited selectively significant inhibitory activity against α-glycosidase derived from yeast. The strongest analog showed almost 50 times the activity of the positive control, deoxynojirimycin. PMID:28124983

  10. Hot isostatically-pressed aluminosilicate glass-ceramic with natural crystalline analogues for immobilizing the calcined high-level nuclear waste at the Idaho Chemical Processing Plant

    SciTech Connect

    Raman, S.

    1993-12-01

    The additives Si, Al, MgO, P{sub 2}O{sub 5} were mechanically blended with fluorinelsodium calcine in varying proportions. The batches were vacuum sealed in stainless steel canisters and hot isostatically pressed at 20,000 PSI and 1000 C for 4 hours. The resulting suite of glass-ceramic waste forms parallels the natural rocks in microstructural and compositional heterogeneity. Several crystalline phases ar analogous in composition and structure to naturally occurring minerals. Additional crystalline phases are zirconia and Ca-Mg borate. The glasses are enriched in silica and alumina. Approximately 7% calcine elements occur dissolved in this glass and the total glass content in the waste forms averages 20 wt%. The remainder of the calcine elements are partitioned into crystalline phases at 75 wt% calcine waste loading. The waste forms were tested for chemical durability in accordance with the MCC1-test procedure. The leach rates are a function of the relative proportions of additives and calcine, which in turn influence the composition and abundances of the glass and crystalline phases. The DOE leach rate criterion of less than 1 g/m{sup 2}-day is met by all the elements B, Cs and Na are increased by lowering the melt viscosity. This is related to increased crystallization or devitrification with increases in MgO addition. This exploratory work has shown that the increases in waste loading occur by preferred partitioning of the calcine components among crystalline and glass phases. The determination of optimum processing parameters in the form of additive concentration levels, homogeneous blending among the components, and pressure-temperature stabilities of phases must be continued to eliminate undesirable effects of chemical composition, microstructure and glass devitrification.

  11. Geochemical baseline studies of soil in Finland

    NASA Astrophysics Data System (ADS)

    Pihlaja, Jouni

    2017-04-01

    The soil element concentrations regionally vary a lot in Finland. Mostly this is caused by the different bedrock types, which are reflected in the soil qualities. Geological Survey of Finland (GTK) is carrying out geochemical baseline studies in Finland. In the previous phase, the research is focusing on urban areas and mine environments. The information can, for example, be used to determine the need for soil remediation, to assess environmental impacts or to measure the natural state of soil in industrial areas or mine districts. The field work is done by taking soil samples, typically at depth between 0-10 cm. Sampling sites are chosen to represent the most vulnerable areas when thinking of human impacts by possible toxic soil element contents: playgrounds, day-care centers, schools, parks and residential areas. In the mine districts the samples are taken from the areas locating outside the airborne dust effected areas. Element contents of the soil samples are then analyzed with ICP-AES and ICP-MS, Hg with CV-AAS. The results of the geochemical baseline studies are published in the Finnish national geochemical baseline database (TAPIR). The geochemical baseline map service is free for all users via internet browser. Through this map service it is possible to calculate regional soil baseline values using geochemical data stored in the map service database. Baseline data for 17 elements in total is provided in the map service and it can be viewed on the GTK's web pages (http://gtkdata.gtk.fi/Tapir/indexEN.html).

  12. 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.

  13. New synthetic routes to chain-extended selenium, sulfur, and nitrogen analogues of the naturally occurring glucosidase inhibitor salacinol and their inhibitory activities against recombinant human maltase glucoamylase.

    PubMed

    Liu, Hui; Nasi, Ravindranath; Jayakanthan, Kumarasamy; Sim, Lyann; Heipel, Heather; Rose, David R; Pinto, B Mario

    2007-08-17

    Six heteroanalogues (X = S, Se, NH) of the naturally occurring glucosidase inhibitor salacinol, containing polyhydroxylated, acyclic chains of 6-carbons, were synthesized for structure-activity studies with different glycosidase enzymes. The target zwitterionic compounds were synthesized by means of nucleophilic attack of the PMB-protected 1,4-anhydro-4-seleno-, 1,4-anhydro-4-thio-, and 1,4-anhydro-4-imino-D-arabinitols at the least hindered carbon atom of 1,3-cyclic sulfates. These 1,3-cyclic sulfates were derived from D-glucose and D-galactose, and significantly, they utilized butane diacetal as the protecting groups for the trans 2,3-diequatorial positions. Deprotection of the coupled products proceeded smoothly, unlike in previous attempts with different protecting groups, and afforded the target selenonium, sulfonium, and ammonium sulfates with different stereochemistry at the stereogenic centers. The four new heterosubstituted compounds (X = Se, NH) inhibited recombinant human maltase glucoamylase (MGA), one of the key intestinal enzymes involved in the breakdown of glucose oligosaccharides in the small intestine. The two selenium derivatives each had Ki values of 0.10 microM, giving the most active compounds to date in this general series of zwitterionic glycosidase inhibitors. The two nitrogen compounds also inhibited MGA but were less active, with Ki values of 0.8 and 35 microM. The compounds in which X = S showed Ki values of 0.25 and 0.17 microM. Comparison of these data with those reported previously for related compounds reinforces the requirements for an effective inhibitor of MGA. With respect to chain extension, the configurations at C-2' and C-4' are critical for activity, the configuration at C-3', bearing the sulfate moiety, being unimportant. It would also appear that the configuration at C-5' is important but the relationship is dependent on the heteroatom.

  14. 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.

  15. Genetic engineering to produce polyketide analogues.

    PubMed

    Reeves, Christopher D; Rodriguez, Eduardo

    2009-01-01

    Polyketides are pharmaceutically important and structurally diverse natural products. Creating analogues for drug development can be done with chemistry, but this is generally restricted to a few accessible functional groups. Analogues can also be made by genetic engineering, which is particularly effective for polyketides synthesized by a modular polyketide synthase (PKS). Such a PKS displays colinearity, which means that the structural features along the polyketide chain are determined by the catalytic specificities in corresponding modules along a molecular assembly line. The assembly line can be genetically engineered through addition, deletion, or mutation of catalytic domains or the reorganization of whole modules. Chemically synthesized precursors also can be fed to engineered assembly lines to further expand the repertoire of analogues. These various methods are discussed with an aim of providing a guide to the strategies most likely to succeed in a given circumstance. Recent information that could be relevant to future polyketide engineering projects is also discussed.

  16. 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

  17. Heteroatom-Containing Porphyrin Analogues.

    PubMed

    Chatterjee, Tamal; Shetti, Vijayendra S; Sharma, Ritambhara; Ravikanth, Mangalampalli

    2017-02-22

    The heteroatom-containing porphyrin analogues or core-modified porphyrins that resulted from the replacement of one or two pyrrole rings with other five-membered heterocycles such as furan, thiophene, selenophene, tellurophene, indene, phosphole, and silole are highly promising macrocycles and exhibit quite different physicochemical properties compared to regular azaporphyrins. The properties of heteroporphyrins depend on the nature and number of different heterocycle(s) present in place of pyrrole ring(s). The heteroporphyrins provide unique and unprecedented coordination environments for metals. Unlike regular porphyrins, the monoheteroporphyrins are known to stabilize metals in unusual oxidation states such as Cu and Ni in +1 oxidation states. The diheteroporphyrins, which are neutral macrocycles without ionizable protons, also showed interesting coordination chemistry. Thus, significant progress has been made in last few decades on core-modified porphyrins in terms of their synthesis, their use in building multiporphyrin arrays for light-harvesting applications, their use as ligands to form interesting metal complexes, and also their use for several other studies. The synthetic methods available in the literature allow one to prepare mono- and diheteroporphyrins and their functionalized derivatives, which were used extensively to prepare several covalent and noncovalent heteroporphyrin-based multiporphyrin arrays. The methods are also developed to synthesize different hetero analogues of porphyrin derivatives such as heterocorroles, heterochlorins, heterocarbaporphyrinoids, heteroatom-substituted confused porphyrins, and so on. This Review summarizes the key developments that have occurred in heteroporphyrin chemistry over the last four decades.

  18. Synthesis of chalcone analogues with increased antileishmanial activity.

    PubMed

    Boeck, Paula; Bandeira Falcão, Camila Alves; Leal, Paulo César; Yunes, Rosendo Augusto; Filho, Valdir Cechinel; Torres-Santos, Eduardo Caio; Rossi-Bergmann, Bartira

    2006-03-01

    Eighteen analogues of an active natural chalcone were synthesized using xanthoxyline and some derivatives, and these analogues were tested for selective activity against both promastigotes and intracellular amastigotes of Leishmania amazonensis in vitro. Three analogues (10, 12, and 19) containing nitro, fluorine or bromine groups, respectively, displayed increased selective activity against the parasites as compared with the natural chalcone. The nitrosylated chalcone 10 was also tested intralesionally in infected mice and was found to be as effective as Pentostan reference drug at a dose 100 times higher than that of the chalcone in controlling both the lesion growth and the parasite burden.

  19. 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.

  20. Geochemical Speciation Mass Transfer

    SciTech Connect

    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 mineral 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.

  1. [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.

  2. 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.

  3. 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.

  4. Environmental Applications of Geochemical Modeling

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Anderson, Greg

    2002-05-01

    This book discusses the application of geochemical models to environmental practice and studies, through the use of numerous case studies of real-world environmental problems, such as acid mine drainage, pit lake chemistry, nuclear waste disposal, and landfill leachates. In each example the authors clearly define the environmental threat in question; explain how geochemical modeling may help solve the problem posed; and advise the reader how to prepare input files for geochemical modeling codes and interpret the results in terms of meeting regulatory requirements.

  5. Germananes: Germanium Graphane Analogues

    NASA Astrophysics Data System (ADS)

    Goldberger, Joshua

    2014-03-01

    Graphene's success has shown that it is not only possible to create stable, single-atom thick sheets from a crystalline solid, but that these materials have fundamentally different properties than the parent material. Our interest focuses on the synthesis and properties of Group IV graphane analogues. We have synthesized for the first time, mm-scale crystals of a hydrogen-terminated germanium multilayered graphane analogue (germanane, GeH) from the topochemical deintercalation of CaGe2. This layered van der Waals solid is analogous to multilayered graphane. The surface layer of GeH only slowly oxidizes in air over the span of five months, while the underlying layers are resilient to oxidation. We demonstrate that it is possible to covalently terminate the external surface with organic substituents to tune the electronic structure, and enhance the stability. These materials represent a new class of covalently terminated graphane analogues having great potential for a wide range of optoelectronic and sensing applications, especially since theory predicts a direct band gap of 1.53 eV and an electron mobility of 18,000 cm2/Vs which is five times higher than that of bulk Ge.

  6. 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.

  7. 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.

    2016-12-01

    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.

  8. Geochemical Characteristics of Mercury in Oil and Gas

    NASA Astrophysics Data System (ADS)

    Yan, Qituan; Han, Zhongxi; Wang, Shuying

    2017-05-01

    As an important element in oil and gas, the process of mercury formation, migration and enrichment, has an important practical significance to determine the nature and preservation status of deep oil-gas reservoirs, which can provide reliable geochemical basis for oil-gas exploration departments. Therefore, basing on the study of mercury formation, migration and enrichment, the geochemical anomaly patterns of mercury are determined, and the geochemical characteristics in oil and gas are discussed. Study shows that the mercury have strong affinity with oil and gas, and it will migrate and accumulate with the maturation of kerogen; Because of the abyssal faults, magmatic activity and deep geological process, in some petroliferous basins, the oil type gas have higher mercury content; On the basis of geochemical anomaly characteristics and morphological combination of mercury in surface, the anomaly patterns in oil and gas geochemical exploration are summarized to guide the anomaly interpretation and evaluation of testing zone, so as to provide the reliable geochemical basis for oil and gas exploration department.

  9. Geochemical processes at mineral surfaces

    SciTech Connect

    Davis, J.A.; Hayes, K.F.

    1986-01-01

    This volume includes 32 papers which were presented at a symposium on geochemical processes at mineral-water interfaces in 1985 and which bring to bear on this area a very wide range of expertise. The discontinuities in properties which occur at the mineral-water interface have profound effects on the movement of naturally occurring ions. Weathering and precipitation processes control the concentrations and speciation of ions in natural waters and the movements of these within the hydrosphere; both classes of processes take place at mineral-water interfaces. After an introductory overview, the book is divided into seven major sections, each dealing with one of the aspects of the processes occurring at the mineral-water interface. Five papers deal with the physical properties of the mineral-water interface; these represent a well-balanced mix of experimental and theoretical (mathematical modeling) work. Adsorption phenomena are dealt with in another five papers; these are largely experimental in character. Ion-exchange processes are discussed in four papers, one of which addresses the use of relaxation methods to study ion exchange kinetics at the microscopic level. Spectroscopic techniques (including electron-spin resonance and Moessbauer spectroscopy) are utilized in four papers. Chemical reactions, mainly redox processes, at mineral-water interfaces are treated in four papers, one of which deals with non-biological organic reactions. Solid-solution formation and equilibria are the subjects of another set of four articles, and the last group of papers deals with the processes involved in precipitation and dissolution, including weathering.

  10. 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

  11. 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.

  12. Catalytic antioxidants: regenerable tellurium analogues of vitamin E.

    PubMed

    Singh, Vijay P; Poon, Jia-fei; Engman, Lars

    2013-12-20

    In an effort to improve the chain-breaking capacity of the natural antioxidants, an octyltelluro group was introduced next to the phenolic moiety in β- and δ-tocopherol. The new vitamin E analogues quenched peroxyl radicals more efficiently than α-tocopherol and were readily regenerable by aqueous N-acetylcysteine in a simple membrane model composed of a stirring chlorobenzene/water two-phase system. The novel tocopherol analogues could also mimic the action of the glutathione peroxidase enzymes.

  13. 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.

  14. 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)

  15. 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

  16. 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.

  17. 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.

  18. Benchmarking analogue models of brittle thrust wedges

    NASA Astrophysics Data System (ADS)

    Schreurs, Guido; Buiter, Susanne J. H.; Boutelier, Jennifer; Burberry, Caroline; Callot, Jean-Paul; Cavozzi, Cristian; Cerca, Mariano; Chen, Jian-Hong; Cristallini, Ernesto; Cruden, Alexander R.; Cruz, Leonardo; Daniel, Jean-Marc; Da Poian, Gabriela; Garcia, Victor H.; Gomes, Caroline J. S.; Grall, Céline; Guillot, Yannick; Guzmán, Cecilia; Hidayah, Triyani Nur; Hilley, George; Klinkmüller, Matthias; Koyi, Hemin A.; Lu, Chia-Yu; Maillot, Bertrand; Meriaux, Catherine; Nilfouroushan, Faramarz; Pan, Chang-Chih; Pillot, Daniel; Portillo, Rodrigo; Rosenau, Matthias; Schellart, Wouter P.; Schlische, Roy W.; Take, Andy; Vendeville, Bruno; Vergnaud, Marine; Vettori, Matteo; Wang, Shih-Hsien; Withjack, Martha O.; Yagupsky, Daniel; Yamada, Yasuhiro

    2016-11-01

    We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing

  19. 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

  20. 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.

  1. Kriging - a challenge in geochemical mapping

    NASA Astrophysics Data System (ADS)

    Stojdl, Jiri; Matys Grygar, Tomas; Elznicova, Jitka; Popelka, Jan; Vachova, Tatina; Hosek, Michal

    2017-04-01

    Geochemists can easily provide datasets for contamination mapping thanks to recent advances in geographical information systems (GIS) and portable chemical-analytical instrumentation. Kriging is commonly used to visualise the results of such mapping. It is understandable, as kriging is a well-established method of spatial interpolation. It was created in 1950's for geochemical data processing to estimate the most likely distribution of gold based on samples from a few boreholes. However, kriging is based on the assumption of continuous spatial distribution of numeric data that is not realistic in environmental geochemistry. The use of kriging is correct when the data density is sufficient with respect to heterogeneity of the spatial distribution of the geochemical parameters. However, if anomalous geochemical values are focused in hotspots of which boundaries are insufficiently densely sampled, kriging could provide misleading maps with the real contours of hotspots blurred by data smoothing and levelling out individual (isolated) but relevant anomalous values. The data smoothing can thus it results in underestimation of geochemical extremes, which may in fact be of the greatest importance in mapping projects. In our study we characterised hotspots of contamination by uranium and zinc in the floodplain of the Ploučnice River. The first objective of our study was to compare three methods of sampling: random (based on stochastic generation of sampling points), systematic (square grid) and judgemental sampling (based on judgement stemming from principles of fluvial deposition) as the basis for pollution maps. The first detected problem in production of the maps was the reduction of the smoothing effect of kriging using appropriate function of empirical semivariogram and setting the variation of at microscales smaller than the sampling distances to minimum (the "nugget" parameter of semivariogram). Exact interpolators such as Inverse Distance Weighting (IDW) or Radial

  2. Forensic Analysis using Geological and Geochemical Techniques

    NASA Astrophysics Data System (ADS)

    Hoogewerff, J.

    2009-04-01

    Due to the globalisation of legal (and illegal) trade there is an increasing demand for techniques which can verify the geographical origin and transfer routes of many legal and illegal commodities and products. Although geological techniques have been used in forensic investigations since the emergence of forensics as a science in the late eighteen hundreds, the last decade has seen a marked increase in geo-scientists initiating concept studies using the latest analytical techniques, including studying natural abundance isotope variations, micro analysis with laser ablation ICPMS and geochemical mapping. Most of the concept studies have shown a good potential but uptake by the law enforcement and legal community has been limited due to concerns about the admissibility of the new methods. As an introduction to the UGU2009 session "Forensic Provenancing using Geological and Geochemical Techniques" I will give an overview of the state of the art of forensic geology and the issues that concern the admissibility of geological forensic evidence. I will use examples from the NITECRIME and FIRMS networks, the EU TRACE project and other projects and literature to illustrate the important issues at hand.

  3. Microbial sulfur isotope fractionation in a Mars analogue environment at Rio Tinto, SW Spain

    NASA Astrophysics Data System (ADS)

    Velasco, E.; Mason, P.; Vroon, P.; Röling, W.; Davies, G.

    2011-10-01

    Abundant sulfate minerals are present on Mars hence sulfur isotopes are likely to be a key tool for the detection of any past or present life. To investigate the link between the activity of sulfate reducing microorganisms and sulfur isotope fractionation, we incubated sediments from a modern hyper-acidic, Ferich subareal environment at Rio Tinto, SW Spain. This site has been frequently used as a geochemical analogue of Mars. Sediments were sampled from the upper part of Rio Tinto (Marismilla) and the estuary (Moguer). Laboratory incubations were carried out at 30°C, using an artificial input solution with sulfate in excess [1]. Electron donors were provided by the natural substrate. Initial data indicate moderate biological sulfate reduction rates of between 5 and 90 nmol·cm-3·h-1 both in Marismilla and in Moguer, independent of the pH of the input solution. Sulfur isotope fractionation was extreme in the Moguer estuary, extending beyond the maximum of 47‰ predicted by the standard Rees model [2]. These data indicate that sulfur isotopes have a potential to be sensitive indicators of biotic activity in Martian environments containing sulfate minerals.

  4. The relevance of analogue studies for understanding obsessions and compulsions.

    PubMed

    Abramowitz, Jonathan S; Fabricant, Laura E; Taylor, Steven; Deacon, Brett J; McKay, Dean; Storch, Eric A

    2014-04-01

    Analogue samples are often used to study obsessive-compulsive (OC) symptoms and related phenomena. This approach is based on the hypothesis that results derived from such samples are relevant to understanding OC symptoms in individuals with a diagnosis of obsessive-compulsive disorder (OCD). Two decades ago, Gibbs (1996) reviewed the available literature and found initial support for this hypothesis. Since then there have been many important advances addressing this issue. The purpose of the present review was to synthesize various lines of research examining the assumptions of using analogue samples to draw inferences about people with OCD. We reviewed research on the prevalence of OC symptoms in non-clinical populations, the dimensional (vs. categorical) nature of these symptoms, phenomenology, etiology, and studies on developmental and maintenance factors in clinical and analogue samples. We also considered the relevance of analogue samples in OCD treatment research. The available evidence suggests research with analogue samples is highly relevant for understanding OC symptoms. Guidelines for the appropriate use of analogue designs and samples are suggested.

  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. Nature

    NASA Astrophysics Data System (ADS)

    Heinhorst, Sabine; Cannon, Gordon

    1997-01-01

    The fact that two of the original articles by this year's Nobel laureates were published in Nature bears witness to the pivotal role of this journal in documenting pioneering discoveries in all areas of science. The prize for Physiology or Medicine was awarded to immunologists Peter C. Doherty (University of Tennessee) and Rolf M. Zinkernagel (University of Zurich, Switzerland), honoring work that, in the 1970s, laid the foundation for our current understanding of the way in which our immune system differentiates between healthy cells and virus-infected ones that are targeted for destruction (p 465 in the October 10 issue of vol. 383). Three researchers share the Chemistry award for their discovery of C60 buckminsterfullerenes. The work by Robert Curl, Richard Smalley (both at Rice University), and Harry Kroto (University of Sussex, UK) has led to a burst of new approaches to materials development and in carbon chemistry (p 561 of the October 17 issue of vol. 383). This year's Nobel prize in physics went to three U.S. researchers, Douglas Osheroff (Stanford University) and David M. Lee and Robert C. Richardson (Cornell University), who were honored for their work on superfluidity, a frictionless liquid state, of supercooled 3He (p 562 of the October 17 issue of vol. 383).

  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. 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.

  9. 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

  10. 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.

  11. Geochemical barriers for environment protection and recovery of nonferrous metals.

    PubMed

    Chanturiya, Valentine; Masloboev, Vladimir; Makarov, Dmitriy; Nesterov, Dmitriy; Bajurova, Julia; Svetlov, Anton; Men'shikov, Yuriy

    2014-01-01

    A study of natural minerals, ore tailings and their products as materials for artificial geochemical barriers is presented. In particular, it focuses on interaction between calcite and dolomite and sulfate solutions containing nickel, copper and iron under static conditions. Calcite of -0.1 mm fraction has been shown to perform well as a barrier when added to water phases of tailing dumps and natural reservoirs. Experiments under dynamic conditions have revealed a high potential of thermally activated copper-nickel tailings as barriers. After a 500-day precipitating period on a geochemical barrier, the contents of nickel and copper in ore dressing tailings were found to increase 12- and 28-fold, respectively. An effective sorbent of copper, iron and nickel ions is a brucite-based product of hydrochloric acid treatment of vermiculite ore tailings. Its sorption capacity can be essentially increased through thermal activation.

  12. PTH analogues and osteoporotic fractures.

    PubMed

    Verhaar, Harald J J; Lems, Willem F

    2010-09-01

    At present there are two parathyroid hormone (PTH) analogues (PTH 1 - 34 and PTH 1 - 84) registered for the treatment of established osteoporosis in postmenopausal women (PTH 1 - 34 and PTH 1 - 84) and in men (PTH 1 - 34 only) who are at increased risk of having a fracture. The efficacy and safety of PTH 1 - 34 and PTH 1 - 84 in the management of osteoporosis is evaluated by reviewing published literature and presentations from scientific meetings through to 2010. This review focuses on data on fracture risk reduction and safety endpoints of PTH analogues. The adverse reactions reported most are nausea, pain in the extremities, headache and dizziness. Exogenous PTH analogues, given as daily subcutaneous injections, stimulate bone formation, increase bone mass and bone strength, and improve calcium balance. In postmenopausal women with osteoporosis, PTH analogues reduced the risk of vertebral (PTH 1 - 34 and PTH 1 - 84) and non-vertebral fractures (only PTH 1 - 34). In men and women with glucocorticosteroid-induced osteoporosis, PTH 1 - 34 reduced the risk of vertebral fractures. In general, PTH analogues are well tolerated with an acceptable safety profile: they can be used for the prevention and treatment of fractures in postmenopausal women with severe, established osteoporosis.

  13. 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.

  14. The synthesis of insect juvenile hormones and their analogues

    NASA Astrophysics Data System (ADS)

    Odinokov, Viktor N.; Kukovinets, Olga S.; Zainullin, R. A.; Tolstikov, Genrikh A.

    1992-07-01

    The methods of synthesis of insect juvenile hormones and their natural and synthetic analogues (juvenoids) are considered. Much attention is paid to juvenoids of the 2,4-dienoate class, including oxa and aza derivatives and cyclic and heterocyclic compounds, which display selective activity towards vairous forms of insect. The bibliography includes 263 references.

  15. 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

  16. 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.

  17. 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.

  18. Summary geochemical maps of the Harrison 1° x 2° quadrangle, Arkansas and Missouri

    USGS Publications Warehouse

    Erickson, R.L.; Chazin, Barbara; Erickson, M.S.

    1989-01-01

    Geochemical studies of the Harrison lo x 2° quadrangle, Arkansas and Missouri, are part of a joint multidisciplinary study by the U.S. Geological Survey; the Division of Geology and Land Survey, Missouri Department of Natural Resources; and the Arkansas Geological Commission. The objective of the joint study is to assess the mineral-resource potential of the area by integrated geologic, geochemical, and geophysical investigations.

  19. Derivatisable Cyanobactin Analogues: A Semisynthetic Approach

    PubMed Central

    Oueis, Emilia; Adamson, Catherine; Mann, Greg; Ludewig, Hannes; Redpath, Philip; Migaud, Marie

    2015-01-01

    Abstract Many natural cyclic peptides have potent and potentially useful biological activities. Their use as therapeutic starting points is often limited by the quantities available, the lack of known biological targets and the practical limits on diversification to fine‐tune their properties. We report the use of enzymes from the cyanobactin family to heterocyclise and macrocyclise chemically synthesised substrates so as to allow larger‐scale syntheses and better control over derivatisation. We have made cyclic peptides containing orthogonal reactive groups, azide or dehydroalanine, that allow chemical diversification, including the use of fluorescent labels that can help in target identification. We show that the enzymes are compatible and efficient with such unnatural substrates. The combination of chemical synthesis and enzymatic transformation could help renew interest in investigating natural cyclic peptides with biological activity, as well as their unnatural analogues, as therapeutics. PMID:26507241

  20. Pressor effects of tryptamine analogues.

    PubMed Central

    Bosin, T R; Hixson, E J; Maickel, R P

    1976-01-01

    1. Methylation of tryptamine in the 1-position had little effect on the potency of the drug as a pressor agent in the intact anaesthetized rat. 2. In contrast, substitution of a benzo[b]thiophene ring system for the indole ring decreased the pressor activity. 3. Pretreatment of the animals with reserpine reduced the pressor effect of tryptamine and its benzo[b]thiophene analogue while increasing the effect of the 1-methylindole analogue. 4. Pretreatment with phenoxybenzamine reduced the pressor effect of all three compounds. PMID:1252662

  1. Neuroprotective actions of a histidine analogue in models of ischemic stroke.

    PubMed

    Tang, Sung-Chun; Arumugam, Thiruma V; Cutler, Roy G; Jo, Dong-Gyu; Magnus, Tim; Chan, Sic L; Mughal, Mohamed R; Telljohann, Richard S; Nassar, Matthew; Ouyang, Xin; Calderan, Andrea; Ruzza, Paolo; Guiotto, Andrea; Mattson, Mark P

    2007-05-01

    Histidine is a naturally occurring amino acid with antioxidant properties, which is present in low amounts in tissues throughout the body. We recently synthesized and characterized histidine analogues related to the natural dipeptide carnosine, which selectively scavenge the toxic lipid peroxidation product 4-hydroxynonenal (HNE). We now report that the histidine analogue histidyl hydrazide is effective in reducing brain damage and improving functional outcome in a mouse model of focal ischemic stroke when administered intravenously at a dose of 20 mg/kg, either 30 min before or 60 min and 3 h after the onset of middle cerebral artery occlusion. The histidine analogue also protected cultured rat primary neurons against death induced by HNE, chemical hypoxia, glucose deprivation, and combined oxygen and glucose deprivation. The histidine analogue prevented neuronal apoptosis as indicated by decreased production of cleaved caspase-3 protein. These findings suggest a therapeutic potential for HNE-scavenging histidine analogues in the treatment of stroke and related neurodegenerative conditions.

  2. Missions to Mars: Characterisation of Mars analogue rocks for the International Space Analogue Rockstore (ISAR)

    NASA Astrophysics Data System (ADS)

    Bost, Nicolas; Westall, Frances; Ramboz, Claire; Foucher, Frédéric; Pullan, Derek; Meunier, Alain; Petit, Sabine; Fleischer, Iris; Klingelhöfer, Göstar; Vago, Jorge L.

    2013-07-01

    Instruments for surface missions to extraterrestrial bodies should be cross-calibrated using a common suite of relevant materials. Such work is necessary to improve instrument performance and aids in the interpretation of in-situ measurements. At the CNRS campus in Orléans, the Observatoire des Sciences de l'Univers en région Centre (OSUC) has created a collection of well-characterised rocks and minerals for testing and calibrating instruments to be flown in space missions. The characteristics of the analogue materials are documented in an accompanying online database. In view of the recent and upcoming rover missions to Mars (NASA's 2011 Mars Science Laboratory (MSL) and ESA/Roscosmos' 2018 ExoMars), we are concentrating initially on materials of direct relevance to the red planet. The initial collection consists of 15 well-studied rock and mineral samples, including a variety of basalts (ultramafic, weathered, silicified, primitive), sediments (volcanic sands, chert, and a banded iron formation -BIF-), and the phyllosilicate nontronite (a clay). All the samples were characterised petrographically, petrologically, and geochemically using the types of analyses likely to be performed during in-situ missions, in particular ExoMars: hand specimen description; optical microscopy; mineralogical analysis by XRD, Raman and IR spectrometry; iron phase analysis by Mössbauer spectroscopy (MBS), elemental analysis by Energy-Dispersive X-ray spectroscopy (EDX), microprobe, Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Mass Spectrometry (ICP-MS); and reduced carbon analysis by Raman spectrometry.

  3. 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.

  4. 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.

  5. Synthesis and antioxidant activity of a procyanidin B3 analogue.

    PubMed

    Mizuno, Mirei; Nakanishi, Ikuo; Matsubayashi, Satoko; Imai, Kohei; Arai, Takuya; Matsumoto, Ken-Ichiro; Fukuhara, Kiyoshi

    2017-02-15

    Proanthocyanidin, an oligomer of catechin, is a natural antioxidant and a potent inhibitor of lectin-like oxidized LDL receptor-1, which is involved in the pathogenesis of arteriosclerosis. We synthesized proanthocyanidin analogue 1, in which the geometry of one catechin molecule in procyanidin B3, a dimer of (+)-catechin, is constrained to be planar. The antioxidant activities of the compounds were evaluated in terms of their capacities to scavenge galvinoxyl radicals, and results demonstrate that while procyanidin was 3.8 times more potent than (+)-catechin, the radical scavenging activity of proanthocyanidin analogue 1 was further increased to 1.9 times that of procyanidin B3. This newly designed proanthocyanidin analogue 1 may be a promising lead compound for the treatment of arteriosclerosis and related cerebrovascular diseases.

  6. Migrastatin analogues target fascin to block tumour metastasis.

    PubMed

    Chen, Lin; Yang, Shengyu; Jakoncic, Jean; Zhang, J Jillian; Huang, Xin-Yun

    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.

  7. 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.

  8. 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.

  9. Analogue earthquakes and seismic cycles: experimental modelling across timescales

    NASA Astrophysics Data System (ADS)

    Rosenau, Matthias; Corbi, Fabio; Dominguez, Stephane

    2017-05-01

    Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short- and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.

  10. Properties, metabolisms, and applications of (L)-proline analogues.

    PubMed

    Bach, Thi Mai Hoa; Takagi, Hiroshi

    2013-08-01

    Due to the unique role of L-proline in the folding and structure of protein, a variety of synthetic proline analogues have been developed. L-Proline analogues have been proven to be valuable reagents for studying cellular metabolism and the regulation of macromolecule synthesis in both prokaryotic and eukaryotic cells. In addition to these fundamental researches, they are useful compounds for industrial use. For instance, microorganisms that overproduce L-proline have been obtained by isolating mutants resistant to L-proline analogues. They are also promising candidates for tuning the biological, pharmaceutical, or physicochemical properties of naturally occurring or de novo designed peptides. Among L-proline analogues, L-azetidine-2-carboxylic acid (L-AZC) is a toxic non-proteinogenic amino acid originally found in lily of the valley plants and trans-4-hydroxy-L-proline (4-L-THOP) is the most abundant component of mammalian collagen. Many hydroxyprolines (HOPs), such as 4-L-THOP and cis-4-hydroxy-L-proline (4-L-CHOP), are useful chiral building blocks for the organic synthesis of pharmaceuticals. In addition, L-AZC and 4-L-CHOP, which are potent inhibitors of cell growth, have been tested for their antitumor activity in tissue culture and in vivo. In this review, we describe the recent discoveries regarding the physiological properties and microbial production and metabolism of L-proline analogues, particularly L-AZC and HOPs. Their applications in fundamental research and industrial use are also discussed.

  11. Nanochannels: biological channel analogues.

    PubMed

    Pradeep, H; Rajanikant, G K

    2012-06-01

    The flux of ions across the biological membrane is a central activity to many cellular processes, from conduction of nerve impulse to the apoptosis. Traffic of ions or molecules across the membrane and organelles is governed by natural machines of great precision; ion channels, a special class of proteins, reside in the biological membranes. Recent studies in the field of nanoscience have concentrated on to precisely mimic the physical and chemical properties of these pores that make them increasingly attractive in this field. Synthetic nanoporous materials have a great deal of medical applications, including biosensing, biosorting, immune-isolation and drug delivery. In this review, the authors briefly describe the interesting synthetic channels that are extensively studied, and also attempt to furnish a precise overview of recent advances in this arena.

  12. Fetal bovine serum influences the stability and bioactivity of resveratrol analogues: A polyphenol-protein interaction approach.

    PubMed

    Tang, Fen; Xie, Yixi; Cao, Hui; Yang, Hua; Chen, Xiaoqing; Xiao, Jianbo

    2017-03-15

    Fetal bovine serum (FBS) is a universal growth supplement of cell and tissue culture media. Herein, the influences of FBS on the stability and antioxidant activity of 21 resveratrol analogues were investigated using a polyphenol-protein interaction approach. The structure-stability relationships of resveratrol analogues in FBS showed a clear decrease in the stability of hydroxylated resveratrol analogues in the order: resorcinol-type>pyrogallol-type>catechol-type. The glycosylation and methoxylation of resveratrol analogues enhanced their stability. A linear relationship between the stability of resveratrol analogues in FBS and the affinity of resveratrol analogues-FBS interaction was found. The oxidation process is not the only factor governing the stability of resveratrol analogues in FBS. These results facilitated the insightful investigation of the role of polyphenol-protein interactions in serum, thereby providing some fundamental clues for future clinical research and pharmacological studies on natural small molecules.

  13. 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

  14. Geochemical Characteristics of Typhoon - and Tsunami - Induced Deposits from Western Kyushu Islands

    NASA Astrophysics Data System (ADS)

    Kanamaru, K.; Woodruff, J. D.; Kundu, S.; Cook, T.

    2014-12-01

    Western Kyushu Island is a region of Japan frequently impacted by typhoon landfalls. This region is relatively tectonically stable with few active faults and therefore known for far fewer great earthquakes when compared to the Nankai Trough region. Only a few studies have examined the history of tsunamis impacting the region. Hence, studies from western Kyushu provide a unique opportunity to study tsunami deposits in a broader geographic context in order to delineate regional typhoon impacts. This study presents results from both modern analogue from Typhoon Neoguri in 2014 and legendary Kamikaze Typhoons from 13th century. The initial coring was conducted in 2010. Total of 9 sediment cores were collected from two natural freshwater lakes along the western coast of Kyushu: Lake Daija (32.248°N, 129.985°E) and Lake Kawahara (32.624°N, 129.831°E). In order to further understand the characteristics of typhoon deposits, we collected 4 additional sediment cores from Kawahara in July of 2014, approximately one week after landfall of Typhoon Neoguri. We use a multi-proxy approach to identify event deposits. These approaches include loss on ignition, X-Ray fluorescence, X-radiograph, grain size, magnetic susceptibility, and SEM/EDS analyses. Initial results yielded commonalities between the two lakes. Linear interpolation of the most prominent event deposits within multiple cores, presenting highs in Sr and Ca intensities, constrain the dates of deposits of interest to the late 13th century—consistent with the Mongol invasions. Here we present preliminary geochemical results from Lake Kawahara, which further constrain the typhoon deposits, and use this as a reference event for comparison to tsunami deposits found in other regions.

  15. 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.

  16. Slip dynamics in an analogue faultzone

    NASA Astrophysics Data System (ADS)

    Rudolf, Michael; Rosenau, Matthias; Oncken, Onno

    2017-04-01

    Elastic stress in the lithosphere releases through slip along pre-existing planes of weakness (fault zones). Slip events may occur on many spatial and temporal scales. They range from short-term localised seismic slip (earthquakes) to aseismic slip transients and long-term distributed slip in cataclastic or ductile shear zones. The interplay of seismic and aseismic fault slip is poorly understood, potentially complex and very costly to model numerically. Therefore, we designed an analogue experiment using a rate-and-state frictional material (fused glass beads), that shows unstable (seismic) and stable (aseismic) slip. This is embedded in an elastic material (ballistic gelatin) that models upper crustal elastic rebound. In the analogue model presented here, we examine the influence of multiple parameters on the slip dynamics and overall statistics of ruptures within a glass bead shear zone. We use a customised rotary shear apparatus (Schulze ring-shear tester) to monitor shear stress during shear. The apparatus allows a direct control of shear rate and normal stress. Its transparent lid enables concurrent monitoring of the frictional contact surface. Digital image correlation is used to measure on-fault deformation. Because of the rate-and-state frictional properties of glass beads (a-b = -0.0138), the used setup produces regular stick-slip events under certain normal loading and strain rate conditions. Preliminary analysis shows the following: The events feature statistics similar to natural slip systems, i.e. a magnitude distribution similar to single faults. Estimated moment magnitudes of the laboratory earthquakes range from MW = -7 to -6. A Gutenberg-Richter like decay up to a certain corner magnitude followed by a characteristic peak is observable. With decreasing loading rate the recurrence time and size of events increase exponentially with exponents similar to natural events. Rupture dynamics are characterised by a transition from two-dimensional crack

  17. Geochemical study of Palong Pluton at Negeri Sembilan-Pahang border

    NASA Astrophysics Data System (ADS)

    Selamat Din, Khairil Izam Bin; Umor, Mohd Rozi

    2013-11-01

    The geochemical studies are carried out for igneous rocks from Palong Pluton at the border area of Negeri Sembilan and Pahang. The study area is about 250 km2, covering the area of Kemayan, Pasoh and Serting. The purposes of the geochemical study are to classify and determine the chemical characteristic of the granitic rocks, to correlate and interpret the crystallization history of igneous rocks, to determine the rock genesis and to determine the origin of magma. The Palong Pluton is divided into three groups, namely the Kemayan Granite, Serting Granite and Lui Granite. The geochemical data are presented by TAS and Harker Diagrams. The geochemical results show that Kemayan Granite, Serting Granite and Lui Granite are naturally originated from a single magma source. The magma evolution started from Kemayan Granite to Lui Granite and Serting Granite by differentiation proceses.

  18. Smaragdyrins and Sapphyrins Analogues.

    PubMed

    Chatterjee, Tamal; Srinivasan, A; Ravikanth, Mangalampalli; Chandrashekar, Tavarakere K

    2017-02-22

    Porphyrins and expanded porphyrins have attracted the attention of chemists for a long time in view of their diverse applications in catalysis; as anion, cation, and neutral substrate receptors; as ligands to coordinate large metal ions; as nonlinear optical materials, MRI contrasting agents, and sensitizers for photodynamic therapy (PDT); and more recently as models for aromaticity (both Hückel and Möbius). A diverse range of synthetic expanded porphyrins containing up to 96π electrons have been reported, and their properties have been exploited for various applications. The present Review is only confined to 22π electron expanded porphyrins containing five pyrrole/heterocyclic rings such as sapphyrins and smaragdyrins. Even though these two macrocycles contain 22π electrons and five pyrrole/heterocyclic rings, they are structurally different. In sapphyrins, the five pyrrole/heterocyclic rings are connected through four meso-carbon bridges and one direct pyrrole-pyrrole bond, whereas in smaragdyrins, the five pyrrole/heterocyclic rings are connected through three meso-carbon bridges and two direct pyrrole-pyrrole bonds. The chemistry of sapphyrins has been well-established in recent years due to the availability of easy and efficient synthetic methods. On the other hand, smaragdyrins are not explored significantly because of their unstable nature. However, recently it was shown that smaragdyrins can be stabilized if one of the pyrrole rings is replaced with a furan ring to afford stable oxasmaragdyrin. The availability of oxasmaragdyrin allowed the exploration of smaragdyrin in recent years. Thus, an attempt has been made in this Review to describe the chemistry of both sapphyrins and smaragdyrins in terms of their synthesis, characterization, metal ion coordination, and anion-recognition properties.

  19. 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.

  20. Geochemical challenge to earthquake prediction.

    PubMed

    Wakita, H

    1996-04-30

    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.

  1. 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

  2. PHREEQC. Geochemical Speciation Mass Transfer

    SciTech Connect

    Parkhurst, D.L.

    1995-01-01

    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 mineral 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.

  3. Comparative studies of the antioxidant effects of a naturally occurring resveratrol analogue -- trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene and resveratrol -- against oxidation and nitration of biomolecules in blood platelets.

    PubMed

    Olas, Beata; Wachowicz, Barbara; Nowak, Pawel; Stochmal, Anna; Oleszek, Wieslaw; Glowacki, Rafal; Bald, Edward

    2008-08-01

    The action of two phenolic compounds isolated from the bark of Yucca schidigera: trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene and its analogue -- resveratrol (trans-3,4',5-trihydroxystilbene, present also in grapes and wine) on oxidative/nitrative stress induced by peroxynitrite (ONOO(-), which is strong physiological oxidant and inflammatory mediator) in human blood platelets was compared. The trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene, like resveratrol, significantly inhibited protein carbonylation and nitration (measured by enzyme-linked immunosorbent assay method) in the blood platelets treated with peroxynitrite (0.1 mM) and markedly reduced an oxidation of thiol groups of proteins (estimated with 5,5'-dithio-bis(2-nitro-benzoic acid)] or glutathione (measured by high performance liquid chromatography method) in these cells. The trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene, like resveratrol, also caused a distinct reduction of platelet lipid peroxidation induced by peroxynitrite. The obtained results indicate that in vitro trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene and resveratrol have very similar protective effects against peroxynitrite-induced oxidative/nitrative damage to the human platelet proteins and lipids. Moreover, trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene proved to be even more potent than resveratrol in antioxidative tests. We conclude that the novel tested phenolic compound -- trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene isolated from Y. schidigera bark possessing Generally Recognized As Safe label given by the Food and Drug Administration and allows their human dietary use -- seems to be a promising candidate for future evaluations of its antioxidative activity and may be a good candidate for scavenging peroxynitrite.

  4. Neuronal Analogues of Conditioning Paradigms

    DTIC Science & Technology

    1984-04-24

    Although the mechanisms of interneuronal communication have been well established, the changes underlying most forms of learning have thus far eluded...stimulating electrodes on one of the connectives was adjusted so as to produce a small excitatory postsynaptic potential ( EPSP ) in the impaled cell...two stimuli would constitute a neuronal analogue of conditioning by producing an increased EPSP in response to the test stimulus alone. If so, then

  5. Desferrithiocin Analogue Uranium Decorporation Agents

    PubMed Central

    Bergeron, Raymond J.; Wiegand, Jan; Singh, Shailendra

    2010-01-01

    Purpose Previous systematic structure-activity studies of the desferrithiocin (DFT) platform have allowed the design and synthesis of analogues and derivatives of DFT that retain the exceptional iron-clearing activity of the parent, while eliminating its adverse effects. We hypothesized that a similar approach could be adopted to identify DFT-related analogues that could effectively decorporate uranium. Materials and Methods The decorporation properties of nine DFT-related analogues were determined in a bile duct-cannulated rat model. Diethylenetriaminepentaacetic acid (DTPA) served as a positive control. Selected ligands also underwent multiple and delayed dosing regimens. Uranium excretion in urine and bile or stool was determined by inductively coupled plasma mass spectroscopy (ICP-MS); tissue levels of uranium were also assessed. Results The two best clinical candidates are (S)-4,5-dihydro-2-[2-hydroxy-4-(3,6,9-trioxadecyloxy)phenyl]-4-methyl-4-thiazolecarboxylic acid [(S)-4'-(HO)-DADFT-PE (9)], with a 57% reduction in kidney uranium levels on oral (p.o.) administration and (S)-4,5-dihydro-2-[2-hydroxy-3-(3,6,9-trioxadecyloxy)phenyl]-4-methyl-4-thiazolecarboxylic acid [(S)-3'-(HO)-DADFT-PE (10)], with a 62% renal reduction on p.o. administration. The majority of the metal excretion promoted by these analogues is in the bile, thus further reducing kidney actinide exposure. Conclusions While 9 administered p.o. or subcutaneously (s.c.) immediately post-metal is an effective decorporation agent, withholding the dose (s.c.) until 4 h reduced the activity of the compound. Conversion of 9 to its isopropyl ester may circumvent this issue. PMID:19399680

  6. 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.

  7. 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.

  8. 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.

  9. Detection of organometallic and radical intermediates in the catalytic mechanism of methyl-coenzyme M reductase using the natural substrate methyl-coenzyme M and a coenzyme B substrate analogue.

    PubMed

    Dey, Mishtu; Li, Xianghui; Kunz, Ryan C; Ragsdale, Stephen W

    2010-12-28

    Methyl-coenzyme M reductase (MCR) from methanogenic archaea catalyzes the terminal step in methanogenesis using coenzyme B (CoBSH) as the two-electron donor to reduce methyl-coenzyme M (methyl-SCoM) to form methane and the heterodisulfide, CoBS-SCoM. The active site of MCR contains an essential redox-active nickel tetrapyrrole cofactor, coenzyme F(430), which is active in the Ni(I) state (MCR(red1)). Several catalytic mechanisms have been proposed for methane synthesis that mainly differ in whether an organometallic methyl-Ni(III) or a methyl radical is the first catalytic intermediate. A mechanism was recently proposed in which methyl-Ni(III) undergoes homolysis to generate a methyl radical (Li, X., Telser, J., Kunz, R. C., Hoffman, B. M., Gerfen, G., and Ragsdale, S. W. (2010) Biochemistry 49, 6866-6876). Discrimination among these mechanisms requires identification of the proposed intermediates, none of which have been observed with native substrates. Apparently, intermediates form and decay too rapidly to accumulate to detectible amounts during the reaction between methyl-SCoM and CoBSH. Here, we describe the reaction of methyl-SCoM with a substrate analogue (CoB(6)SH) in which the seven-carbon heptanoyl moiety of CoBSH has been replaced with a hexanoyl group. When MCR(red1) is reacted with methyl-SCoM and CoB(6)SH, methanogenesis occurs 1000-fold more slowly than with CoBSH. By transient kinetic methods, we observe decay of the active Ni(I) state coupled to formation and subsequent decay of alkyl-Ni(III) and organic radical intermediates at catalytically competent rates. The kinetic data also revealed substrate-triggered conformational changes in active Ni(I)-MCR(red1). Electron paramagnetic resonance (EPR) studies coupled with isotope labeling experiments demonstrate that the radical intermediate is not tyrosine-based. These observations provide support for a mechanism for MCR that involves methyl-Ni(III) and an organic radical as catalytic intermediates

  10. 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

  11. 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.

  12. 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.

  13. 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.

  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. The Nb/La vs Th/La representation: a relevant geochemical tool for the analysis of mantle related processes Insights on the residual state and nature of large scale mantle sources heterogeneities

    NASA Astrophysics Data System (ADS)

    Loubet, M. J.

    2009-12-01

    differentiation) than the previous OIB’s and MORB’s sources, being more Th/La enriched for similar Nb/La ratio and more 208Pb/204Pb enriched for similar 206Pb/204Pb ratio. Several interpretations can be advanced for the nature of these last OIB material sources: recycled oceanic crust segments differentiated from older more primitive mantle sources (preferred explanation for most of these OIB’s), recycled oceanic crust material enriched in recycled Continental crust and/or sublithospheric material. The spatial repartition of these last more enriched OIB’s allows to associate them to the two superplumes uprising respectively in the Central Pacific and below South Africa. This analysis supports a layered mantle structure of the mantle with two large scale upper mantle domains distinguishing by distinct residual characteristics, and a “lower mantle layer” (perhaps limited to the D” layer) characterized by more enriched material sources (that is less residual relative to CC differentiation). References: Dupré, B. and Allègre, C.J., Pb-Sr isotope variation in Indian Ocean basalts and mixing phenomena. Nature, 303: 142-146, 1983.

  16. A multi-isotopic and trace element investigation of the Cretaceous-Tertiary boundary layer at Stevns Klint, Denmark - inferences for the origin and nature of siderophile and lithophile element geochemical anomalies

    NASA Astrophysics Data System (ADS)

    Frei, Robert; Frei, Karin M.

    2002-10-01

    Os, Sr, Nd and Pb isotope data were collected from a profile across the Cretaceous-Tertiary (K-T) boundary layer at Stevns Klint, Denmark. ɛNd [ T=65 Ma] values from within the boundary layer (Fish Clay) are lower by ˜1 ɛ unit than those of the underlying Maastrichtian limestone and the overlying Danian chalk sequences. Systematic profile-upward changes of Pb, Sr and Os isotopic compositions and concentrations in the boundary layer cannot be accounted for by in situ growth of daughter products since the sedimentation of the Fish Clay. While Os, Nd and Pb isotopes indicate the admixing of less radiogenic components to the Fish Clay, Sr isotopes show elevated radiogenic values in the boundary layer, relative to the carbonate sequences beneath and above it. The sudden change in lithophile (e.g., Sr, Pb and Nd) isotope compositions at the base of the Fish Clay and profile-upward trends of 87Sr/ 86Sr and 206Pb/ 204Pb ratios towards those of the overlying Danian chalk are interpreted to reflect recovery from enhanced, acid rain-induced continental (local?) weathering input to the seawater. However, a continental crustal source is invalid for the siderophile element Os. In the light of evidence from chromium isotopes for a cosmic origin of the platinum group elements (PGEs) and certain moderately siderophile elements (Cr, Ni, Co, V) in K-T boundary sediments, including Stevns Klint [Shukolyukov and Lugmair, Science 282 (1998) 927-929], and supported by the finding of projectile debris [Bauluz et al., Earth Planet. Sci. Lett. 182 (2000) 127-136] and the occurrence of abundant Ni-rich spinel at many K-T sites [Robin et al., Nature 363 (1993) 615-617; Kyte, Nature 396 (1998) 237-239], we favor to explain the sudden drop of 187Os/ 188Os ratios from 0.210 to 0.160 at the K-T boundary to derive from global fall-out of extraterrestrial matter. The present 186Os/ 188Os ratio of 0.119836±0.000004 measured in the basal layer of the Fish Clay is within the uncertainty a

  17. 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.

  18. 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.

  19. Synthesis of a Functionalized Benzofuran as a Synthon for Salvianolic Acid C Analogues as Potential LDL Antioxidants.

    PubMed

    López-Frías, Gabriela; Camacho-Dávila, Alejandro A; Chávez-Flores, David; Zaragoza-Galán, Gerardo; Ramos-Sánchez, Víctor H

    2015-05-14

    A palladium mediated synthesis of a common synthon for the syntheses of antioxidant analogues of naturally occurring salvianolic acids is presented. The synthetic route may be used to obtain analogues with a balanced lipophilicity/hydrophilicity which may result in potentially interesting LDL antioxidants for the prevention of cardiovascular diseases.

  20. 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.

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

    PubMed

    Rabe, Patrick; Klapschinski, Tim A; Brock, Nelson L; Citron, Christian A; D'Alvise, Paul; Gram, Lone; Dickschat, Jeroen S

    2014-01-01

    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.

  2. 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

  3. 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.

  4. Choline Analogues in Malaria Chemotherapy

    PubMed Central

    Peyrottes, Suzanne; Caldarelli, Sergio; Wein, Sharon; Périgaud, Christian; Pellet, Alain; Vial, Henri

    2012-01-01

    Emerging resistance against well-established anti-malaria drugs warrants the introduction of new therapeutic agents with original mechanisms of action. Inhibition of membrane-based phospholipid biosynthesis, which is crucial for the parasite, has thus been proposed as a novel and promising therapeutic strategy. This review compiles literature concerning the design and study of choline analogues and related cation derivatives as potential anti-malarials. It covers advances achieved over the last two decades and describes: the concept validation, the design and selection of a clinical candidate (Albitiazolium), back-up derivatives while also providing insight into the development of prodrug approaches. PMID:22607139

  5. 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)

  6. 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.

  7. Mass spectrometry and photoelectron spectroscopy of tetracene cluster anions, (tetracene)n- (n = 1-100): evidence for the highly localized nature of polarization in a cluster analogue of oligoacene crystals.

    PubMed

    Mitsui, Masaaki; Ando, Naoto; Nakajima, Atsushi

    2007-10-04

    Photoelectron spectroscopy of tetracene cluster anions, (tetracene)n- (n = 1-100), reveals the coexistence of two types of isomers, designated as isomers I and II-1 (n = 10-50) or isomers I and II-2 (n > 60), in a wide size range. The vertical detachment energies (VDEs) of isomer I increase persistently due to polarization and structural relaxation effects, where a monomeric anion core is encompassed with geometrically reorganized neutral molecules. Conversely, a characteristic ion distribution in the mass spectrum of (tetracene)n-ensues from the two-dimensional (2D) herringbone-type ordering of isomer II-1, whose VDEs remain constant at 1.80 eV for n >/= 14. Also, isomer II-2, presumably adopting multilayered structural motifs, exhibits invariable VDEs of 2.0 eV, a manifestation of significant charge screening effects in these isomers. The invariable nature of the VDEs of isomers II-1 and II-2 unambiguously demonstrates a largely localized nature of polarization induced by the excess charge residing in microscopic crystal-like environments. Surprisingly, only 14 tetracene molecules within a 2D herringbone-type layer including an excess charge can provide the charge stabilization energy corresponding to approximately 80% of that of the crystal, and the rest of the energy is provided by polarization of neutral molecules in adjacent layers.

  8. Adaptive Multiscale Modeling of Geochemical Impacts on Fracture Evolution

    NASA Astrophysics Data System (ADS)

    Molins, S.; Trebotich, D.; Steefel, C. I.; Deng, H.

    2016-12-01

    Understanding fracture evolution is essential for many subsurface energy applications, including subsurface storage, shale gas production, fracking, CO2 sequestration, and geothermal energy extraction. Geochemical processes in particular play a significant role in the evolution of fractures through dissolution-driven widening, fines migration, and/or fracture sealing due to precipitation. One obstacle to understanding and exploiting geochemical fracture evolution is that it is a multiscale process. However, current geochemical modeling of fractures cannot capture this multi-scale nature of geochemical and mechanical impacts on fracture evolution, and is limited to either a continuum or pore-scale representation. Conventional continuum-scale models treat fractures as preferential flow paths, with their permeability evolving as a function (often, a cubic law) of the fracture aperture. This approach has the limitation that it oversimplifies flow within the fracture in its omission of pore scale effects while also assuming well-mixed conditions. More recently, pore-scale models along with advanced characterization techniques have allowed for accurate simulations of flow and reactive transport within the pore space (Molins et al., 2014, 2015). However, these models, even with high performance computing, are currently limited in their ability to treat tractable domain sizes (Steefel et al., 2013). Thus, there is a critical need to develop an adaptive modeling capability that can account for separate properties and processes, emergent and otherwise, in the fracture and the rock matrix at different spatial scales. Here we present an adaptive modeling capability that treats geochemical impacts on fracture evolution within a single multiscale framework. Model development makes use of the high performance simulation capability, Chombo-Crunch, leveraged by high resolution characterization and experiments. The modeling framework is based on the adaptive capability in Chombo

  9. Synthetic analogues of cyanobacterial alkaloid cylindrospermopsin and their toxicological activity.

    PubMed

    Cartmell, Christopher; Evans, Daniel M; Elwood, Jessica M L; Fituri, Hisham S; Murphy, Patrick J; Caspari, Thomas; Poniedziałek, Barbara; Rzymski, Piotr

    2017-10-01

    Cylindrospermopsin (CYN) is a naturally occurring alkaloid produced by a variety of cyanobacteria and known to induce oxidative stress-mediated toxicity in eukaryotic cells. Despite extensive research on the mechanism of CYN toxicity, an understanding of the structural features responsible for this toxicity and the mechanism by which it can enter the cell are still not clear. It was established that the presence of both the uracil and guanidine groups is essential in biological activity of CYN whilst not much is known in this regard on the role of tether that separates them and the attached hydroxyl group. Therefore, in the present study we have prepared three synthetic analogues possessing uracil and guanidine groups separated by a variable length tether (4-6 carbons) and containing a hydroxyl function in a position orientation to CYN, together with a tetracyclic analogue of CYN lacking the hydroxyl group at C-7. The toxicity of these compounds was then compared with CYN and guanidinoacetate (GAA; the primary substrate in CYN biosynthesis) in an in vitro model using human neutrophils isolated from healthy subjects. The lowest activity measured by means of reactive oxygen species generation, lipid peroxidation and cell death was observed for GAA and the tetracyclic analogue. The greatest toxicity was found in an analogue with a 6-carbon tether, but all three analogues and CYN caused rapid onset of redox imbalance. These results add to the general understanding of CYN toxicity and preliminary findings suggest that the -OH group at C-7 may be significant for the cellular transport of CYN and/or be involved in its toxic activity inside the cell, a hypothesis which requires further testing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Sulphamoylated 2-Methoxyestradiol Analogues Induce Apoptosis in Adenocarcinoma Cell Lines

    PubMed Central

    Visagie, Michelle; Theron, Anne; Mqoco, Thandi; Vieira, Warren; Prudent, Renaud; Martinez, Anne; Lafanechère, Laurence; Joubert, Annie

    2013-01-01

    2-Methoxyestradiol (2ME2) is a naturally occurring estradiol metabolite which possesses antiproliferative, antiangiogenic and antitumor properties. However, due to its limited biological accessibility, synthetic analogues have been synthesized and tested in attempt to develop drugs with improved oral bioavailability and efficacy. The aim of this study was to evaluate the antiproliferative effects of three novel in silico-designed sulphamoylated 2ME2 analogues on the HeLa cervical adenocarcinoma cell line and estrogen receptor-negative breast adenocarcinoma MDA-MB-231 cells. A dose-dependent study (0.1–25 μM) was conducted with an exposure time of 24 hours. Results obtained from crystal violet staining indicated that 0.5 μM of all 3 compounds reduced the number of cells to 50%. Lactate dehydrogenase assay was used to assess cytotoxicity, while the mitotracker mitochondrial assay and caspase-6 and -8 activity assays were used to investigate the possible occurrence of apoptosis. Tubulin polymerization assays were conducted to evaluate the influence of these sulphamoylated 2ME2 analogues on tubulin dynamics. Double immunofluorescence microscopy using labeled antibodies specific to tyrosinate and detyrosinated tubulin was conducted to assess the effect of the 2ME2 analogues on tubulin dynamics. An insignificant increase in the level of lactate dehydrogenase release was observed in the compounds-treated cells. These sulphamoylated compounds caused a reduction in mitochondrial membrane potential, cytochrome c release and caspase 3 activation indicating apoptosis induction by means of the intrinsic pathway in HeLa and MDA-MB-231 cells. Microtubule depolymerization was observed after exposure to these three sulphamoylated analogues. PMID:24039728

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Biological activity of silylated amino acid containing substance P analogues.

    PubMed

    Cavelier, F; Marchand, D; Martinez, J; Sagan, S

    2004-03-01

    The need to replace natural amino acids in peptides with nonproteinogenic counterparts to obtain new medicinal agents has stimulated a great deal of innovation on synthetic methods. Here, we report the incorporation of non-natural silylated amino acids in substance P (SP), the binding affinity for the two hNK-1 binding sites and, the potency to stimulate phospholipase C (PLC) and adenylate cyclase of the resulting peptide. We also assess the improvement of their stability towards enzyme degradation. Altogether, we found that replacing glycine with silaproline (Sip) in position 9 of SP leads to a potent analogue exhibiting an increased resistance to angiotensin-converting enzyme hydrolysis.

  16. 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

  17. 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

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

    PubMed

    Mondal, Sukanta; Chattaraj, Pratim Kumar

    2014-09-07

    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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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

  6. New Immunosuppressive Sphingoid Base and Ceramide Analogues in Wild Cordyceps

    PubMed Central

    Mi, Jia-Ning; Han, Yuwei; Xu, Yingqiong; Kou, Junping; Wang, Jing-Rong; Jiang, Zhi-Hong

    2016-01-01

    A comprehensive identification of sphingoid bases and ceramides in wild Cordyceps was performed by integrating a sequential chromatographic enrichment procedure and an UHPLC-ultrahigh definition-Q-TOF-MS based sphingolipidomic approach. A total of 43 sphingoid bases and 303 ceramides were identified from wild Cordyceps, including 12 new sphingoid base analogues and 159 new ceramide analogues based on high-resolution MS and MS/MS data, isotope distribution, matching with the comprehensive personal sphingolipid database, confirmation by sphingolipid standards and chromatographic retention time rule. The immunosuppressive bioassay results demonstrated that Cordyceps sphingoid base fraction exhibits more potent immunosuppressive activity than ceramide fraction, elucidating the immunosuppressive ingredients of wild Cordyceps. This study represented the most comprehensive identification of sphingoid bases and ceramides from a natural source. The findings of this study provided an insight into therapeutic application of wild Cordyceps. PMID:27966660

  7. New Immunosuppressive Sphingoid Base and Ceramide Analogues in Wild Cordyceps.

    PubMed

    Mi, Jia-Ning; Han, Yuwei; Xu, Yingqiong; Kou, Junping; Wang, Jing-Rong; Jiang, Zhi-Hong

    2016-12-14

    A comprehensive identification of sphingoid bases and ceramides in wild Cordyceps was performed by integrating a sequential chromatographic enrichment procedure and an UHPLC-ultrahigh definition-Q-TOF-MS based sphingolipidomic approach. A total of 43 sphingoid bases and 303 ceramides were identified from wild Cordyceps, including 12 new sphingoid base analogues and 159 new ceramide analogues based on high-resolution MS and MS/MS data, isotope distribution, matching with the comprehensive personal sphingolipid database, confirmation by sphingolipid standards and chromatographic retention time rule. The immunosuppressive bioassay results demonstrated that Cordyceps sphingoid base fraction exhibits more potent immunosuppressive activity than ceramide fraction, elucidating the immunosuppressive ingredients of wild Cordyceps. This study represented the most comprehensive identification of sphingoid bases and ceramides from a natural source. The findings of this study provided an insight into therapeutic application of wild Cordyceps.

  8. 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.

  9. Antifreeze glycopeptide analogues: microwave-enhanced synthesis and functional studies.

    PubMed

    Heggemann, Carolin; Budke, Carsten; Schomburg, Benjamin; Majer, Zsuzsa; Wissbrock, Marco; Koop, Thomas; Sewald, Norbert

    2010-01-01

    Antifreeze glycoproteins enable life at temperatures below the freezing point of physiological solutions. They usually consist of the repetitive tripeptide unit (-Ala-Ala-Thr-) with the disaccharide alpha-D-galactosyl-(1-3)-beta-N-acetyl-D-galactosamine attached to each hydroxyl group of threonine. Monoglycosylated analogues have been synthesized from the corresponding monoglycosylated threonine building block by microwave-assisted solid phase peptide synthesis. This method allows the preparation of analogues containing sequence variations which are not accessible by other synthetic methods. As antifreeze glycoproteins consist of numerous isoforms they are difficult to obtain in pure form from natural sources. The synthetic peptides have been structurally analyzed by CD and NMR spectroscopy in proton exchange experiments revealing a structure as flexible as reported for the native peptides. Microphysical recrystallization tests show an ice structuring influence and ice growth inhibition depending on the concentration, chain length and sequence of the peptides.

  10. New homoisoflavonoid analogues protect cells by regulating autophagy.

    PubMed

    Gan, Li-She; Zeng, Lin-Wei; Li, Xiang-Rong; Zhou, Chang-Xin; Li, Jie

    2017-03-15

    As a special group of naturally occurring flavonoids, homoisoflavonoids have been discovered as active components of several traditional Chinese medicines for nourishing heart and mind. In this study, twenty homoisoflavonoid analogues, including different substitution groups on rings A and B, as well as heteroaromatic B ring, were synthesized and evaluated for their cardioprotective and neuroprotective activities. In a H2O2-induced H9c2 cardiomyocytes injury assay, nine homoisoflavonoid analogues showed promising activities in the same level as the positive control, diazoxide. Six cardioprotective compounds with representative structure diversities were then evaluated for their neuroprotective effects on MPP+ induced SH-SY5Y cell injury model. Furthermore, autophagy inducing monodansylcadaverine (MDC) fluorescence staining methods and molecular docking studies indicated the action mechanism of these compounds may involve autophagy regulating via class I PI3K signaling pathway.

  11. Synthetic silvestrol analogues as potent and selective protein synthesis inhibitors.

    PubMed

    Liu, Tao; Nair, Somarajan J; Lescarbeau, André; Belani, Jitendra; Peluso, Stéphane; Conley, James; Tillotson, Bonnie; O'Hearn, Patrick; Smith, Sherri; Slocum, Kelly; West, Kip; Helble, Joseph; Douglas, Mark; Bahadoor, Adilah; Ali, Janid; McGovern, Karen; Fritz, Christian; Palombella, Vito J; Wylie, Andrew; Castro, Alfredo C; Tremblay, Martin R

    2012-10-25

    Misregulation of protein translation plays a critical role in human cancer pathogenesis at many levels. Silvestrol, a cyclopenta[b]benzofuran natural product, blocks translation at the initiation step by interfering with assembly of the eIF4F translation complex. Silvestrol has a complex chemical structure whose functional group requirements have not been systematically investigated. Moreover, silvestrol has limited development potential due to poor druglike properties. Herein, we sought to develop a practical synthesis of key intermediates of silvestrol and explore structure-activity relationships around the C6 position. The ability of silvestrol and analogues to selectively inhibit the translation of proteins with high requirement on the translation-initiation machinery (i.e., complex 5'-untranslated region UTR) relative to simple 5'UTR was determined by a cellular reporter assay. Simplified analogues of silvestrol such as compounds 74 and 76 were shown to have similar cytotoxic potency and better ADME characteristics relative to those of silvestrol.

  12. The future of somatostatin analogue therapy.

    PubMed

    Stewart, P M; James, R A

    1999-10-01

    Since its discovery almost 30 years ago, the mode of action and therapeutic applications of somatostatin have been defined. In particular the cloning and characterization of somatostatin receptor subtypes has facilitated the development of high affinity analogues. In the context of pituitary disease, long-acting somatostatin analogues (octreotide, lanreotide) have been used to treat a variety of pituitary tumours but are most efficacious for the treatment of GH and TSH-secreting adenomas. In patients with acromegaly, depot preparations of these analogues are administered intramuscularly every 10-28 days and provide consistent suppression of GH levels to < 5 mU/l in approximately 50-65% of all cases. Even more specific somatostatin receptor analogues are under development. Finally, radiolabelled somatostatin analogue scintigraphy and, in larger doses, therapy, are now established tools in the evaluation and treatment of neuroendocrine tumours.

  13. Antinociceptive activity of glycosidic enkephalin analogues.

    PubMed

    Rodríguez, R E; Rodríguez, F D; Sacristán, M P; Torres, J L; Reig, F; García Antón, J M; Valencia, G

    1990-01-01

    The antinociceptive activity of two new enkephalin analogues: N1.5-(beta-D-glucopyranosyl)[D-Met2, Pro5]enkephalinamide and N1.5-(beta-D-galactopyranosyl)[D-Met2, Pro5]enkephalinamide was assessed using the tail immersion and paw pressure behavioural tests. Both enkephalin analogues appear to be more active than morphine when injected either into the fourth ventricle or intrathecally; the galactose analogue is more than 5000 times more active than morphine when injected into the fourth ventricle. The analgesic effects produced by the analogues are partially reversed by SC naloxone (0.1 mg/kg) and totally reversed when the dose of naloxone used was 1 mg/kg, suggesting that the analogues act upon more than one type of opiate receptor (mu/delta).

  14. Geochemical asymmetry of the Crozet hotspot

    NASA Astrophysics Data System (ADS)

    Bézos, Antoine; Pimbert, Anthony; Segard, Mélanie; Hémond, Christophe; Guivel, Christèle; Delpech, Guillaume; Beucler, Eric; La, Carole

    2014-05-01

    involved recycling of gabbros instead of bulk oceanic crust. The nature and origin of the least lead radiogenic end-members is then addressed. We propose that those later end-members are best accounted by a depleted upper mantle that have been previously contaminated by a DUPAL component (between 1% to 3% by mass). I summary, the isotopic systematic of the Crozet Archipelago is best explained by a two-step mixing model that constrains the DUPAL component to be located in the upper mantle. Our mixing model implies therefore the presence of two distinct isotopic domains within the Crozet hotspot. The eastern Islands sample one of them and the western Pingouins Islands samples the other one. As suggested for other hotspots showing bilateral asymmetry (e.g. Hawaii), we propose that both isotopic domains could correspond to extensively stretched heterogeneities forming vertical 'geochemical filaments' in the Crozet mantle plume. We finally discuss this model in light of the location of the Crozet hotspot above the contour of African Large Low-Shear-Velocity Province in the deep mantle.

  15. Emulating exhalative chemistry: synthesis and structural characterization of ilinskite, Na[Cu5O2](SeO3)2Cl3, and its K-analogue

    NASA Astrophysics Data System (ADS)

    Kovrugin, Vadim M.; Siidra, Oleg I.; Colmont, Marie; Mentré, Olivier; Krivovichev, Sergey V.

    2015-08-01

    The K- and Na-synthetic analogues of the fumarolic mineral ilinskite have been synthesized by the chemical vapor transport (CVT) reactions method. The A[Cu5O2](SeO3)2Cl3 ( A + = K+, Na+) compounds crystallize in the orthorhombic space group Pnma: a = 18.1691(6) Å, b = 6.4483(2) Å, c = 10.5684(4) Å, V = 1238.19(7) Å3, R 1 = 0.018 for 1957 unique reflections with F > 4σ F for K[Cu5O2](SeO3)2Cl3 ( KI), and a = 17.7489(18) Å, b = 6.4412(6) Å, c = 10.4880(12) Å, V = 1199.0(2) Å3, R 1 = 0.049 for 1300 unique reflections with F > 4σ F for Na[Cu5O2](SeO3)2Cl3 ( NaI). The crystal structures of KI and NaI are based upon the [O2Cu5]6+ sheets consisting of corner-sharing (OCu4)6+ tetrahedra. The Na-for-K substitution results in the significant expansion of the interlayer space and changes in local coordination of some of the Cu2+ cations. The A + cation coordination changes from fivefold (for Na+) to ninefold (for K+). The CVT reactions method provides a unique opportunity to model physicochemical conditions existing in fumarolic environments and may be used not only to model exhalative processes, but also to predict possible mineral phases that may form in fumaroles. In particular, the K analogue of ilinskite is not known in nature, whereas it may well form from volcanic gases in a K-rich local geochemical environment.

  16. 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.

  17. Synthesis of structurally simplified analogues of pancratistatin: truncation of the cyclitol ring.

    PubMed

    Manpadi, Madhuri; Kireev, Artem S; Magedov, Igor V; Altig, Jeff; Tongwa, Paul; Antipin, Mikhail Yu; Evidente, Antonio; van Otterlo, Willem A L; Kornienko, Alexander

    2009-09-18

    Pancratistatin is a phenanthridone-type natural product isolated from several plants of the Amaryllidaceae family. Its potent antiproliferative, antivascular, antiviral, and antiparasitic properties have attracted the attention of synthetic, biological, and medicinal chemists. Pancratistatin's low natural availability and complex structure have steered many of these research projects toward the preparation of its simplified synthetic analogues with useful levels of activity. In this work we have developed synthetic chemistry aimed at the preparation of pancratistatin analogues with a truncated cyclitol portion of the molecule. The described synthetic pathways are based on a highly anti-diastereoselective arylcuprate conjugate addition to gamma-alkoxy-alpha,beta-enoates and syn-selective azidation at the alpha-position of ester enolates. Analogues with the formally cleaved C3-C4 bond, and thus containing an open ring C, as well as a compound containing a truncated lactol moiety in lieu of the cyclitol, were prepared. Several of the analogues exhibited weak antiproliferative activity, with the highest potency observed in the case of the lactol analogue. From these results implications for the design of future pancratistatin analogues are discussed. Furthermore, the synthetic pathways can be used to construct pancratistatin-mimetic libraries, in which the cyclitol moiety is replaced by other cyclic motifs.

  18. Some biochemical properties of an acyclic oligonucleotide analogue. A plausible ancestor of the DNA?

    NASA Astrophysics Data System (ADS)

    Merle, Liliane; Spach, Gérard; Merle, Yves; Sági, János; Szemzö, Attila

    1993-04-01

    As acyclic oligonucleotides have been suggested as a primitive model of DNA or RNA in prebiotic times, we compared some biochemical properties of these analogues to that of natural ones. Firstly, an acyclic analogue of deoxyribonucleoside triphosphates was tested as a potential substrate of enzymes intervening in nucleic acids synthesis. GlyTTP, a dTTP analogue with a missing 2'-methylene group is notaccepted as a substrate by either DNA polymerase or deoxynucleotidyl terminal transferase (TdT). Secondly, themodified dodecathymidylate (GlyT)12, the racemic acyclic sugar analogue of (dT)12, proved to be anefficient primer for DNA polymerase and TdT, though the associative properties of (GlyT)12 are very weak as shown by UV spectroscopy in phosphate buffer without magnesium chloride. But (GlyT)12 has the advantage to be 500-times more stable against hydrolysis by snake venom phosphodiesterase than the corresponding oligothymidylate.

  19. Upscaling Geochemical and Hydrologic Parameters using a Novel Depth Fragmented Approach

    NASA Astrophysics Data System (ADS)

    Arora, B.; Mohanty, B. P.; McGuire, J. T.

    2012-12-01

    Knowledge about effective hydrologic and geochemical properties at field scales is pertinent in predicting and managing the fate and transport of reactive contaminants from landfill and waste management sites. A significant challenge in predicting these reactive contaminant concentrations at large scales is the lack of an efficient upscaling methodology that serves as a link between process understanding gained at the laboratory scale and application needed at the field scale. Here, we explore the concept of a new depth-wise upscaling framework, which addresses the effect of structural heterogeneity on developing scale-appropriate hydrologic and geochemical parameters. A Markov chain Monte Carlo algorithm (MCMC) is used to derive these upscaling parameters, which are tested for variations across heterogeneous systems (layers and lenses) at the Norman landfill site. The Norman landfill is a closed municipal landfill with prevalent organic contamination. The results of the MCMC simulations indicate that the use of a heterogeneity formulation in the likelihood function significantly improves the prediction of geochemical concentrations at the landfill site. The results also indicate that geochemical scaling coefficients based on dominant biogeochemical processes (sulfate and iron reduction) are reproducible for conservative (such as bromide) and other redox-sensitive concentrations (such as nitrate) at the Norman landfill. These geochemical scaling coefficients derived through the upscaling algorithm demonstrate unimodal characteristics in the posterior distribution while the hydrologic scaling coefficient is multimodal in nature. The multi-modality is again suggestive of the effect of heterogeneity and lithologic variability on redox processes at the Norman landfill site.

  20. 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.

  1. Hawai'i and Gale Crater: A Mars Analogue Study of Igneous, Sedimentary, Weathering, and Alteration Trends in Geochemistry

    NASA Technical Reports Server (NTRS)

    Berger, J. A.; Flemming, R. L.; Schmidt, M. E.; Gellert, R.; Morris, R. V.; Ming, D. W.

    2017-01-01

    Sedimentary rocks in Gale Crater on Mars indicate a varied provenance with a range of alteration and weathering [1, 2]. Geochemical trends identified in basaltic and alkalic sedimentary rocks by the Alpha Particle X-ray Spectrometer (APXS) on the Mars rover Curiosity represent a complex interplay of igneous, sedimentary, weathering, and alteration processes. Assessing the relative importance of these processes is challenging with unknown compositions for parent sediment sources and with the constraints provided by Curiosity's instruments. We therefore look to Mars analogues on Earth where higher-resolution analyses and geologic context can constrain interpretations of Gale Crater geochemical observations. We selected Maunakea (AKA Mauna Kea) and Kohala volcanoes, Hawai'i, for an analogue study because they are capped by post-shield transitional basalts and alkalic lavas (hawaiites, mugearites) with compositions similar to Gale Crater [1, 3]. Our aim was to characterize Hawaiian geochemical trends associated with igneous processes, sediment transport, weathering, and alteration. Here, we present initial results and discuss implications for selected trends observed by APXS in Gale Crater.

  2. A Novel Field Apparatus for Conducting Linked Geochemical-Microbiological Experiments in Shallow Sediments

    NASA Astrophysics Data System (ADS)

    Smith, E. W.; Voytek, M. A.; McGuire, J. T.; Cozzarelli, I. M.; Kneeshaw, T. A.; Baez-Cazull, S. E.

    2008-12-01

    Collecting in-situ experimental data for microbially mediated geochemical reactions is complex because it is difficult to assess the impact of the heterogeneity of natural systems. Specifically it is often difficult to constrain the degree of interaction between the pore water collected for geochemical analysis and a sampled microbial population. The newly developed apparatus, called a Native Organism Geochemical Experimentation Enclosure (NOGEE), provides the means to measure changes in well defined geochemical solutions that have been in direct contact with a known in-situ microbial population. The sampling apparatus is similar to a drive-point well. A short screened chamber (~60 ml) at the tip houses a polycarbonate sponge, which serves as a substrate for colonization by native microorganisms when it is open to the surrounding sediment. Following a colonization period dependent on season and temperature, the sponge chamber is closed to the surrounding environment by lowering an inner pipe and amended test solutions are introduced from the surface via tubing. An advantage to this method over laboratory microcosms is that the in-situ setting provides a natural, intrinsic control over environmental variables and minimizes disturbance to the system. To date, NOGEE's have been used to evaluate kinetic controls on sulfate reduction. Experimental results showed changing rates of sulfate reduction coincident with changes in microbial population and demonstrate the utility of using NOGEEs to quantify linkages between geochemistry and microbiology in complex natural environments.

  3. 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

    2015-03-03

    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.

  4. Lead structures for new antibacterials: stereocontrolled synthesis of a bioactive muraymycin analogue.

    PubMed

    Spork, Anatol P; Büschleb, Martin; Ries, Oliver; Wiegmann, Daniel; Boettcher, Stefan; Mihalyi, Agnes; Bugg, Timothy D H; Ducho, Christian

    2014-11-17

    Naturally occurring muraymycin nucleoside antibiotics represent a promising class of novel antibacterial agents. The structural complexity suggests the investigation of simplified analogues as potential lead structures, which can then be further optimized towards highly potent antimicrobials. Herein we report studies on muraymycin-derived potential lead structures lacking an aminoribose motif found in most naturally occurring muraymycins. We have identified a 5'-defunctionalized motif to be ideal in terms of stability and chemical accessibility and have synthesized a full-length muraymycin analogue based on this structure using a novel fully stereocontrolled route. The obtained 5'-deoxy analogue of the natural product muraymycin C4 showed good inhibitory properties towards the bacterial target protein MraY, sufficient pharmacokinetic stability and no cytotoxicity against human cells, thus making it a promising lead for antibacterial drug development. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  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. Synthesis and antioxidant activity of peptide-based ebselen analogues.

    PubMed

    Satheeshkumar, Kandhan; Mugesh, Govindasamy

    2011-04-18

    A series of di- and tripeptide-based ebselen analogues has been synthesized. The compounds were characterized by (1)H, (13)C, and (77)Se NMR spectroscopy and mass spectral techniques. The glutathione peroxidase (GPx)-like antioxidant activity has been studied by using H(2)O(2) , tert-butyl hydroperoxide (tBuOOH), and cumene hydroperoxide (Cum-OOH) as substrates, and glutathione (GSH) as a cosubstrate. Although all the peptide-based compounds have a selenazole ring similar to that of ebselen, the GPx activity of these compounds highly depends on the nature of the peptide moiety attached to the nitrogen atom of the selenazole ring. It was observed that the introduction of a phenylalanine (Phe) amino acid residue in the N-terminal reduces the activity in all three peroxide systems. On the other hand, the introduction of aliphatic amino acid residues such as valine (Val) significantly enhances the GPx activity of the ebselen analogues. The difference in the catalytic activity of dipeptide-based ebselen derivatives can be ascribed mainly to the change in the reactivity of these compounds toward GSH and peroxide. Although the presence of the Val-Ala-CO(2) Me moiety facilitates the formation of a catalytically active selenol species, the reaction of ebselen analogues that has a Phe-Ile-CO(2) Me residue with GSH does not generate the corresponding selenol. To understand the antioxidant activity of the peptide-based ebselen analogues in the absence of GSH, these compounds were studied for their ability to inhibit peroxynitrite (PN)-mediated nitration of bovine serum albumin (BSA) and oxidation of dihydrorhodamine 123. In contrast to the GPx activity, the PN-scavenging activity of the Phe-based peptide analogues was found to be comparable to that of the Val-based compounds. However, the introduction of an additional Phe residue to the ebselen analogue that had a Val-Ala dipeptide significantly reduced the potency of the parent compound in PN-mediated nitration.

  7. Can we teach machines geochemical exploration?

    NASA Astrophysics Data System (ADS)

    Klump, J. F.; Fouedjio, F.

    2016-12-01

    Geochemical surveys are an important part of exploration for mineral resources and in environmental studies. The samples and chemical analyses are often laborious and difficult to obtain and therefore come at a high cost. As a consequence, these surveys are characterised by datasets with large numbers of variables but relatively few data points when compared to conventional big data problems. With more remote sensing platforms and sensor networks being deployed, large volumes of auxiliary data of the surveyed areas are becoming available. The use of these auxiliary data has the potential to improve the prediction of chemical element concentrations over the whole study area. Established geostatistical methods for the prediction of the spatial distributions of chemical elements in geochemical surveys are well understood but require significant pre-processing of the data. Machine learning algorithms, on the other hand, may require less data pre-processing. However, it is not well understood how these methods perform in a geospatial context. In this presentation we use a case study to compare machine learning algorithms against geostatistical methods to compare their performance in a geospatial context. In particular, we test the hypothesis that using geochemical point data and auxiliary remote sensing data can improve the prediction of the spatial distribution of chemical elements in geochemical surveys.

  8. 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.

  9. 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.

  10. 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.

  11. Geochemical Reaction Mechanism Discovery from Molecular Simulation

    DOE PAGES

    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

  12. 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.

  13. 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.

  14. 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

  15. Bilateral Choroidal Metastases from Endobronchial Carcinoid Treated with Somatostatin Analogues

    PubMed Central

    De Bruyn, Deborah; Lamont, Jan; Vanderstraeten, Erik; Van Belle, Simon; Platteau, Elise; De Zaeytijd, Julie; Hoornaert, Kristien P.

    2016-01-01

    Objective: To describe a patient with bilateral multifocal choroidal metastases from an endobronchial carcinoid treated with a somatostatin analogue. Method: A 60-year-old woman presenting with photopsia in the left eye underwent an extensive ophthalmic examination, including fluorescein angiography, OCT and ultrasound. Results: Fundoscopy revealed a small retinal tear in the left eye, for which she received laser treatment. In addition, choroidal masses were detected in both eyes. Her medical history of a pneumectomy for a bronchial carcinoid six years earlier together with recent elevated chromogranin A blood levels prompted a diagnosis of choroidal metastases. Subsequently, a Gallium-68 DOTANOC positron emitting tomography/computer tomography scan revealed a spinal cord metastasis and mediastinal as well as mesenterial lymph node invasion. Systemic treatment with Sandostatin®, a somatostatin analogue was started. Up until two years after the initial presentation and treatment, these choroidal lesions remained stable without any signs of growth. Conclusion: Endobronchial carcinoid tumors have an indolent nature and long-term follow-up is recommended for early detection of metastases. Although treatment with somatostatin analogues rarely induces complete tumor regression, tumor stabilization and prevention of symptoms related to hormone secretion is achieved. This well-tolerated systemic treatment provides a worthy alternative treatment for choroidal metastasis compared to classic radiotherapy without any risk of radiation or laser-related visual loss. PMID:27843513

  16. 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.

  17. 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.

  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. 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

  1. 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

  2. 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.

  3. 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.

  4. 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

    2016-09-11

    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.

  5. Testing geochemical modeling codes using New Zealand hydrothermal systems

    SciTech Connect

    Bruton, C.J.; Glassley, W.E.; Bourcier, W.L.

    1993-12-01

    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of selected portions of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will: (1) ensure that we are providing adequately for all significant processes occurring in natural systems; (2) determine the adequacy of the mathematical descriptions of the processes; (3) check the adequacy and completeness of thermodynamic data as a function of temperature for solids, aqueous species and gases; and (4) determine the sensitivity of model results to the manner in which the problem is conceptualized by the user and then translated into constraints in the code input. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions. The kinetics of silica precipitation in EQ6 will be tested using field data from silica-lined drain channels carrying hot water away from the Wairakei borefield.

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

    PubMed Central

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

    2016-01-01

    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 (Me2+)-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. PMID:26760230

  7. 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.

  8. 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. Copyright © 2015. Published by Elsevier Inc.

  9. 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

  10. 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.

  11. 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.

  12. Baseline and premining geochemical characterization of mined sites

    USGS Publications Warehouse

    Nordstrom, D. Kirk

    2015-01-01

    A rational goal for environmental restoration of new, active, or inactive mine sites would be ‘natural background’ or the environmental conditions that existed before any mining activities or other related anthropogenic activities. In a strictly technical sense, there is no such thing as natural background (or entirely non-anthropogenic) existing today because there is no part of the planet earth that has not had at least some chemical disturbance from anthropogenic activities. Hence, the terms ‘baseline’ and ‘pre-mining’ are preferred to describe these conditions. Baseline conditions are those that existed at the time of the characterization which could be pre-mining, during mining, or post-mining. Protocols for geochemically characterizing pre-mining conditions are not well-documented for sites already mined but there are two approaches that seem most direct and least ambiguous. One is characterization of analog sites along with judicious application of geochemical modeling. The other is reactive-transport modeling (based on careful synoptic sampling with tracer-injection) and subtracting inputs from known mining and mineral processing. Several examples of acidic drainage are described from around the world documenting the range of water compositions produced from pyrite oxidation in the absence of mining. These analog sites provide insight to the processes forming mineralized waters in areas untouched by mining. Natural analog water-chemistry data is compared with the higher metal concentrations, metal fluxes, and weathering rates found in mined areas in the few places where comparisons are possible. The differences are generally 1–3 orders of magnitude higher for acid mine drainage.

  13. 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

  14. Infrared spectroscopy of Mercury analogue materials under simulated Mercury surface temperature conditions

    NASA Astrophysics Data System (ADS)

    Reitze, Maximilian; Morlok, Andreas; Hiesinger, Harald; Weber, Iris; Stojic, Aleksandra

    2017-04-01

    Infrared spectroscopy is a powerful technique for the exploration of planetary surfaces with remote sensing observations [e.g., 1]. The MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument onboard the BepiColombo spacecraft is designed to explore the surface mineralogy of Mercury in the wavelength region from 7 μ m to 14 μ m [2]. Mercury's surface reaches dayside temperatures of about 700 K [3]. It is well known that bondings between atoms change with temperature, resulting in infrared spectra changes with temperature [4]. In particular, rock-forming minerals like silicates show distinct absorption bands in the infrared due to molecular vibrations, for example, of Si-O bondings [4]. To accurately understand and correctly interpret returned MERTIS data, it is necessary to collect laboratory data of analogue materials under condition similar to Mercury [5]. It is known from previous investigations [5] that the Reststrahlenbands of olivine shift with temperature. In this work we report on temperature effects on Mercury analogue materials in ambient air. At the IRIS (Infrared & Raman for Interplanetary Spectroscopy) laboratory in Münster we used a Bruker VERTEX 70v IR spectrometer together with a Harrick heating stage in a Praying Mantis Diffuse Reflectance Accessory to measure mid-infrared reflectance of mineral powder samples with different grain sizes at increasing temperatures. We report on our spectral results for a natural olivine with Fo91 with a grain size range between 63 μ m and 125 μ m as well as a natural labradorite with a grain size range between 90 μ m and 125 μ m. Spectra were collected at 26, 75, 150, 200, 250, 300, and 350 degrees Celsius with a liquid nitrogen cooled MCT detector under normal ambient pressure. To ensure complete thermal equilibrium of our measured samples, we heated them to higher temperatures and subsequently cooled them to the temperatures at which the spectra were taken. For background calibration, we

  15. Isobrassinin and its analogues: novel types of antiproliferative agents.

    PubMed

    Csomós, Péter; Zupkó, István; Réthy, Borbála; Fodor, Lajos; Falkay, George; Bernáth, Gábor

    2006-12-15

    Isobrassinin (2-(S-methyldithiocarbamoylaminomethyl)indole (7a), a regioisomer of the cruciferous phytoalexin brassinin (1), exerted marked antiproliferative effects on the HeLa, A431 and MCF7 cell lines (>78.6% inhibition at 30muM). For structure-activity relationships, further analogues were synthesized. The highest cytotoxic effect was displayed by 2-phenylimino-1,3-thiazino[5,6-b]indole (10) (10 microM, 76.8%-HeLa and 46.3%-MCF7). The effect of the natural phytoalexin brassinin was also determined.

  16. Analogue gravity models from conformal rescaling

    NASA Astrophysics Data System (ADS)

    Hossenfelder, Sabine; Zingg, Tobias

    2017-08-01

    Analogue gravity is based on a mathematical identity between quantum field theory in curved space-time and the propagation of perturbations in certain condensed matter systems. But not every curved space-time can be simulated in such a way. For analogue gravity to work, one needs not only a condensed matter system that generates the desired metric tensor, but this system then also has to obey its own equations of motion. However, the relation to the metric tensor usually overdetermines the equations of the underlying condensed matter system, such that they in general cannot be fulfilled. In this case the desired metric does not have an analogue. Here, we show that the class of metrics that have an analogue is larger than previously thought. The reason is that the analogue metric is only defined up to a choice of parametrization of the perturbation in the underlying condensed matter system. In this way, the class of analogue gravity models can be vastly expanded.

  17. The survival of geochemical mantle heterogeneities

    NASA Astrophysics Data System (ADS)

    Albarede, F.

    2004-12-01

    The last decade witnessed major changes in our perception of the geochemical dynamics of the mantle. Data bases such as PETDB and GEOROC now provide highly constrained estimates of the geochemical properties of dominant rock types and of their statistics, while the new generation of ICP mass spectrometers triggered a quantum leap in the production of high-precision isotopic and elemental data. Such new advances offer a fresh view of mantle heterogeneities and their survival through convective mixing. A vivid example is provided by the new high-density coverage of the Mid-Atlantic ridge by nearly 500 Pb, Nd, and Hf isotopic data. This new data set demonstrates a rich harmonic structure which illustrates the continuing stretching and refolding of subducted plates by mantle convection. Just as for oceanic chemical variability, the survival of mantle geochemical heterogeneities though mantle circulation can be seen as a competition between stirring and renewal. The modern residence (renewal) times of the incompatible lithophile elements in the mantle calculated using data bases vary within a rather narrow range (4-9 Gy). The mantle is therefore not currently at geochemical steady-state and the effect of its primordial layering on modern mantle geochemistry is still strong. Up to 50 percent of incompatible lithophile elements may never have been extracted into the oceanic crust, which generalizes a conclusion reached previously for 40Ar. A balance between the buoyancy flux and viscous dissipation provides frame-independent estimates of the rates of mixing by mantle convection: primordial geochemical anomalies with initial length scales comparable to mantle depths of plate lengths are only marginally visible at the scale of mantle melting underneath mid-ocean ridges (≈~50~km). They may show up, however, in hot spot basalts and even more in melt inclusions. Up to 50 percent primordial material may be present in the mantle, but scattered throughout as small (<~10~km

  18. A geochemical examination of humidity cell tests

    USGS Publications Warehouse

    Maest, Ann; Nordstrom, D. Kirk

    2017-01-01

    Humidity cell tests (HCTs) are long-term (20 to >300 weeks) leach tests that are considered by some to be the among the most reliable geochemical characterization methods for estimating the leachate quality of mined materials. A number of modifications have been added to the original HCT method, but the interpretation of test results varies widely. We suggest that the HCTs represent an underutilized source of geochemical data, with a year-long test generating approximately 2500 individual chemical data points. The HCT concentration peaks and valleys can be thought of as a “chromatogram” of reactions that may occur in the field, whereby peaks in concentrations are associated with different geochemical processes, including sulfate salt dissolution, sulfide oxidation, and dissolution of rock-forming minerals, some of which can neutralize acid. Some of these reactions occur simultaneously, some do not, and geochemical modeling can be used to help distinguish the dominant processes. Our detailed examination, including speciation and inverse modeling, of HCTs from three projects with different geology and mineralization shows that rapid sulfide oxidation dominates over a limited period of time that starts between 40 and 200 weeks of testing. The applicability of laboratory tests results to predicting field leachate concentrations, loads, or rates of reaction has not been adequately demonstrated, although early flush releases and rapid sulfide oxidation rates in HCTs should have some relevance to field conditions. Knowledge of possible maximum solute concentrations is needed to design effective treatment and mitigation approaches. Early flush and maximum sulfide oxidation results from HCTs should be retained and used in environmental models. Factors that complicate the use of HCTs include: sample representation, time for microbial oxidizers to grow, sample storage before testing, geochemical reactions that add or remove constituents, and the HCT results chosen for use

  19. Novel 1alpha,25-dihydroxyvitamin D3 analogues with the side chain at C12.

    PubMed

    González-Avión, Xosé C; Mouriño, Antonio; Rochel, Natacha; Moras, Dino

    2006-03-09

    The plethora of actions of 1alpha,25(OH)2D3 in various systems suggested wide clinical applications of vitamin D nuclear receptor (VDR) ligands in treatments of inflammation, dermatological indication, osteoporosis, cancers, and autoimmune diseases. More than 3000 vitamin D analogues have been synthesized in order to reduce the calcemic side effects while maintaining the transactivation potency of the natural ligand. In light of the crystal structures of the vitamin D nuclear receptor (VDR), novel analogues of the hormone 1alpha,25(OH)2D3 with side chains attached to C-12 were synthesized via the convergent Wittig-Horner approach. Among the compounds studied, the analogue 2b showed the highest binding affinity for VDR and was the most potent at inducing VDR transcriptional activity in a transient transfection assay (20% of the transactivation activity of the natural ligand).

  20. Emotional impact feedback affects how people remember an analogue trauma event.

    PubMed

    Takarangi, Melanie K T; Segovia, Daisy A; Dawson, Evan; Strange, Deryn

    2014-01-01

    Do external motivational processes-in the form of social influences-shape people's memories for trauma? In this experiment, we examined the effects of social influence on memory and post-traumatic stress disorder (PTSD) symptomology for an analogue traumatic event. Seventy-two participants watched a distressing film; some received feedback about others' reactions to the film that either emphasised or downplayed the distressing nature of the film; control participants received no feedback. A week later, participants reported their symptoms, rated their memory on a number of characteristics and we tested their memory for the film's content. Participants who received feedback downplaying the film reported fewer PTSD-related analogue symptoms and weaker memory characteristics than their counterparts. The results suggest that people's memory phenomenology and analogue symptoms are influenced by others' feedback, but only when others' reactions downplayed the distressing nature of the film.

  1. Geochemical indicators of intrinsic bioremediation

    SciTech Connect

    Borden, R.C.; Gomez, C.A.; Becker, M.T.

    1995-03-01

    A detailed field investigation has been completed at a gasoline-contaminated aquifer near Rocky Point, NC, to examine possible indicators of intrinsic bioremediation and identify factors that may significantly influence the rae and extent of bioremediation. The dissolved plume of benzene, toluene, ethylbenzene, and xylene (BTEX) in ground water is naturally degrading. Toluene and o-xylene are most rapidly degraded followed by m-, p-xylene, and benzene. Ethylbenzene appears to degrade very slowly under anaerobic conditions present in the center of the plume. The rate and extent of biodegradation appears to be strongly influenced by the type and quantity of electron acceptors present in the aquifer. At the upgradient edge of the plume, nitrate, ferric iron, and oxygen are used as terminal electron acceptors during hydrocarbon biodegradation. The equivalent of 40 to 50 mg/l of hydrocarbon is degraded based on the increase in dissolved CO{sub 2} relative to background ground water. Immediately downgradient of the source area, sulfate and iron are the dominant electron acceptors. Toluene and o-xylene are rapidly removed in this region. Once the available oxygen, nitrate, and sulfate are consumed, biodegradation is limited and appears to be controlled by mixing and aerobic biodegradation at the plume fringes.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. Synthesis and Evaluation of a Library of Fluorescent Dipeptidomimetic Analogues as Substrates for Modified Bacterial Ribosomes.

    PubMed

    Chowdhury, Sandipan Roy; Chauhan, Pradeep S; Dedkova, Larisa M; Bai, Xiaoguang; Chen, Shengxi; Talukder, Poulami; Hecht, Sidney M

    2016-05-03

    Described herein are the synthesis and photophysical characterization of a library of aryl-substituted oxazole- and thiazole-based dipeptidomimetic analogues, and their incorporation into position 66 of green fluorescent protein (GFP) in lieu of the natural fluorophore. These fluorescent analogues resemble the fluorophore formed naturally by GFP. As anticipated, the photophysical properties of the analogues varied as a function of the substituents at the para position of the phenyl ring. The fluorescence emission wavelength maxima of compounds in the library varied from ∼365 nm (near-UV region) to ∼490 nm (visible region). The compounds also exhibited a large range of quantum yields (0.01-0.92). The analogues were used to activate a suppressor tRNACUA and were incorporated into position 66 of GFP using an in vitro protein biosynthesizing system that employed engineered ribosomes selected for their ability to incorporate dipeptides. Four analogues with interesting photophysical properties and reasonable suppression yields were chosen, and the fluorescent proteins (FPs) containing these fluorophores were prepared on a larger scale for more detailed study. When the FPs were compared with the respective aminoacyl-tRNAs and the actual dipeptide analogues, the FPs exhibited significantly enhanced fluorescence intensities at the same concentrations. Part of this was shown to be due to the presence of the fluorophores as an intrinsic element of the protein backbone. There were also characteristic shifts in the emission maxima, indicating the environmental sensitivity of these probes. Acridon-2-ylalanine and oxazole 1a were incorporated into positions 39 and 66 of GFP, respectively, and were shown to form an efficient Förster resonance energy transfer (FRET) pair, demonstrating that the analogues can be used as FRET probes.

  7. Glucagonlike Peptide 2 Analogue Teduglutide

    PubMed Central

    Chaturvedi, Lakshmi S.; Basson, Marc D.

    2015-01-01

    IMPORTANCE Short bowel syndrome occurs when a shortened intestine cannot absorb sufficient nutrients or fluids. Teduglutide is a recombinant analogue of human glucagonlike peptide 2 that reduces dependence on parenteral nutrition in patients with short bowel syndrome by promoting enterocytic proliferation, increasing the absorptive surface area. However, enterocyte function depends not only on the number of cells that are present but also on differentiated features that facilitate nutrient absorption and digestion. OBJECTIVE To test the hypothesis that teduglutide impairs human intestinal epithelial differentiation. DESIGN AND SETTING We investigated the effects of teduglutide in the modulation of proliferation and differentiation in human Caco-2 intestinal epithelial cells at a basic science laboratory. This was an in vitro study using Caco-2 cells, a human-derived intestinal epithelial cell line commonly used to model enterocytic biology. EXPOSURE Cells were exposed to teduglutide or vehicle control. MAINOUTCOMESAND MEASURES We analyzed the cell cycle by bromodeoxyuridine incorporation or propidium iodide staining and flow cytometry and measured cell proliferation by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. We used quantitative reverse transcription–polymerase chain reaction to assay the expression of the enterocytic differentiation markers villin, sucrase-isomaltase, glucose transporter 2 (GLUT2), and dipeptidyl peptidase 4 (DPP-4), as well as that of the putative differentiation signals schlafen 12 (SLFN12) and caudal-related homeobox intestine-specific transcription factor (Cdx2). Villin promoter activity was measured by a luciferase-based assay. RESULTS The MTS assay demonstrated that teduglutide increased cell numbers by a mean (SD) of 10% (2%) over untreated controls at a maximal 500nM (n = 6, P < .05). Teduglutide increased bromodeoxyuridine-positive cells vs untreated controls by a mean (SD

  8. Geochemical engineering and materials program plan

    SciTech Connect

    1982-08-01

    The Department of Energy (DOE) was designated as lead agency in discharging the overall legislative mandate for federal R&D to assist the private sector in developing appropriate technology for exploiting geothermal energy resources. The Geochemical Engineering and Materials (GEM) Program was conceived, as part of DOE'S overall strategy, to address specific and plant-wide problems and uncertainties in the use of materials and in geochemical engineering. This program assists industry in the conduct of long-term,high-risk R&D needed to overcome the significant technical and economic GEM-related obstacles faced by developers and potential developers of this alternative energy source. The program focuses on: (1) Increasing the knowledge about the properties of materials and their performance under geothermal energy system conditions; (2) Developing and utilizing more reliable and/or cost-effective materials than previously available; and (3) Developing a greater understanding of and control over geochemical processes during fluid production and transport, energy conversion, and waste management. As a stand-alone program and as support to other DOE geothermal technology development programs, the GEM Program contributes to the feasibility of designing and operating efficient, reliable, and safe fluid handling and energy conversion systems.

  9. Past and present of analogue modelling, and its future trend

    NASA Astrophysics Data System (ADS)

    Koyi, Hemin

    2015-04-01

    Since Hull (1815) published his article on modelling, analogue modelling has expanded to simulate both a wider range of tectonic regimes and target more challenging set-ups, and has become an integrated part of the fields of tectonics and structural geology. Establishment of new laboratories testifies for the increased attention the technique receives. The ties between modellers and field geoscientists have become stronger with the focus being on understanding the parameters that govern the evolution of a tectonic regime and the processes that dominate it. Since the first sand castle was built with damp sand on a beach, sand has proven to be an appropriate material analogue. Even though granular materials is the most widely used analogue material, new materials are also (re)introduced as rock analogues. Emphasis has been on more precise measurements of the mechanical properties of the materials and on minimizing the preparation effects, which have a great impact on scaling, interpretations and benchmarking. The analytical technique used to quantify model results has also seen a great deal of improvement. In addition to X-ray tomography used to visualise internal structures of models, new techniques (e.g. PIV, high-resolution laser scanning, and interferometry) have enabled monitoring kinematics with a higher precision. Benchmarking exercises have given modelling an additional checking tool by outlining, in addition to the rheology of the modelling materials, the impact of different preparation approaches, the effect of boundary conditions, and the human factor on model results. However, despite the different approaches and deformation rigs, results of models of different tectonic laboratories have shown a great deal of similarities. Even with the introduction of more sophisticated numerical codes and usage of more powerful computers which enable the simulation of more challenging material properties and combinations of those, and 3D model set-up, analogue modelling

  10. 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

  11. Reduced peptide bond pseudopeptide analogues of neurotensin.

    PubMed

    Doulut, S; Rodriguez, M; Lugrin, D; Vecchini, F; Kitabgi, P; Aumelas, A; Martinez, J

    1992-01-01

    Pseudopeptide analogues of the C-terminal hexapeptide of neurotensin (H-Arg-Arg-Pro-Tyr-Ile-Leu-OH) were obtained by replacing each peptide bond by the reduced peptide bond CH2NH. The resulting analogues were then examined for their ability to inhibit binding of labeled neurotensin to new-born mouse brain membranes and for stimulation of guinea pig ileum contraction. Replacement of the Ile12-Leu13, Tyr11-Ile12, Pro10-Tyr11 and Lys9-Pro10 peptide bonds resulted in about 2000-, 3400-, 200- and 3400-fold losses, respectively, in binding affinity and 400-, 750-, 250- and 300-fold losses, respectively, in biological activity. Replacement of both Arg8 and Arg9 by lysine led to an analogue exhibiting the same pharmacological profile as the C-terminal hexapeptide of neurotensin. Interestingly, replacement of the Lys8-Lys9 peptide bond by the CH2NH bond produced an analogue exhibiting the same affinity for neurotensin receptors, but 10 times more potent in stimulating guinea pig ileum contraction. N-terminal protected analogues (by the Boc group) showed decreased potency as compared with their amino-free corresponding compounds.

  12. Analogue Downscaling of Seasonal Rainfall Forecasts

    NASA Astrophysics Data System (ADS)

    Charles, A. N.; Timbal, B.; Hendon, H.

    2010-12-01

    We have taken an existing statistical downscaling model (SDM), based on meteorological analogues that was developed for downscaling climate change projections (Timbal et al 2009), and applied it in the seasonal forecasting context to produce downscaled rainfall hindcasts from a coupled model seasonal forecast system (POAMA). Downscaling of POAMA forecasts is required to provide seasonal climate information at local scales of interest. Analogue downscaling is a simple technique to generate rainfall forecasts appropriate to the local scale by conditioning on the large scale predicted GCM circulation and the local topography and climate. Analogue methods are flexible and have been shown to produce good results when downscaling 20th century South Eastern Australian rainfall output from climate models. A set of re-forecasts for three month rainfall at 170 observing stations in the South Murray Darling region of Australia were generated using predictors from the POAMA re-forecasts as input for the analogue SDM. The predictors were optimised over a number of different GCMS in previous climate change downscaling studies. Downscaling with the analogue SDM results in predicted rainfall with realistic variance while maintaining the modest predictive skill of the dynamical model. Evaluation of the consistency between the large scale mean of downscaled and direct GCM output precipitation is encouraging.

  13. On the mechanical analogue of DNA.

    PubMed

    Yakushevich, Ludmila

    2017-03-01

    The creation of mechanical analogues of biological systems is known as a useful instrument that helps to understand better the dynamical mechanisms of the functioning of living organisms. Mechanical analogues of biomolecules are usually constructed for imitation of their internal mobility, which is one of the most important properties of the molecules. Among the different types of internal motions, angular oscillations of nitrous bases are of special interest because they make a substantial contribution to the base pairs opening that in turn is an important element of the process of the DNA-protein recognition. In this paper, we investigate the possibility to construct a mechanical analogue for imitation of angular oscillations of nitrous bases in inhomogeneous DNA. It is shown that the analogue has the form of a mechanical chain of non-identical pendulums that oscillate in the gravitational field of the Earth and coupled by identical springs. The masses and lengths of pendulums, as well as the distances between neighboring pendulums and the rigidity of springs are calculated. To illustrate the approach, we present the result of construction of the mechanical analogue of the fragment of the sequence of bacteriophage T7D.

  14. 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.

  15. Constructing Adequate Non-Speech Analogues: What Is Special about Speech Anyway?

    ERIC Educational Resources Information Center

    Rosen, Stuart; Iverson, Paul

    2007-01-01

    Vouloumanos and Werker (2007) claim that human neonates have a (possibly innate) bias to listen to speech based on a preference for natural speech utterances over sine-wave analogues. We argue that this bias more likely arises from the strikingly different saliency of voice melody in the two kinds of sounds, a bias that has already been shown to…

  16. Mutnovsky and Gorely Volcanoes, Kamchatka as Planetary Analogue Sites

    NASA Astrophysics Data System (ADS)

    Evdokimova, N.; Izbekov, P. E.; Krupskaya, V.; Muratov, A.

    2016-12-01

    Recent advances in Mars studies suggest that volcanic rocks, which dominated Martian surface in the past, have been exposed to alteration processes in a water-bearing environment during Noachian, before 3.7 Gy. Active volcanoes on Earth are natural laboratories, where volcanic processes and their associated products can be studied directly. This is particularly important for studying of alteration of juvenile volcanic products in aqueous environment because of the transient nature of some of the alteration products, as well as the environment itself. Terrestrial analogues help us to better understand processes on Mars; they are particularly useful as a test sites for preparation to future Mars missions. In this presentation we describe planetary analogue sites at Mutnovsky and Gorely Volcanoes in Kamchatka, which might be helpful for comparative studies and preparation to future Mars missions. Mutnovsky and Gorely Volcanoes are located 75 km south of Petropavlovsk-Kamchatsky, in the southern part of the Kamchatka Peninsula, Russia. The modern volcanic landscape in the area was shaped in Holocene (recent 10,000 years) through intermittent eruption of magmas ranging in composition from basalts to dacites and rhyodacites, with basaltic andesite lavas dominating in the modern relief. Two localities could be of a particular interest: (1) Mutnovsky NW thermal field featuring processes of active hydrothermal alteration of lavas of basaltic andesite and (2) dry lake at the bottom of Gorely caldera featuring products of mechanical disintegration of basaltic andesite lavas by eolian processes with short seasonal sedimentation in aqueous environment.

  17. 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.

  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 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 NO3-N) are found in the aerobic waters; low concentrations of NO3 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 CO2 which has then reacted with the igneous rocks. Increases in B

  20. Significance of targeting polyamine metabolism as an antineoplastic strategy: unique targets for polyamine analogues.

    PubMed

    Casero, Robert A; Frydman, Benjamin; Stewart, Tracy Murray; Woster, Patrick M

    2005-01-01

    The polyamines, putrescine, spermidine, and spermine, are naturally occurring polycationic alkylamines that are absolutely required for eukaryotic cell growth. Importantly, the polyamine metabolic pathway, as well as the requirement of polyamines for cell growth, is frequently dysregulated in cancer cells, thus providing a unique set of targets for therapeutic intervention. Ornithine decarboxylase (ODC), a rate-limiting enzyme in polyamine biosynthesis, is frequently up-regulated in preneoplastic cells, and has been implicated as an oncogene in multiple tumor types. Several model systems have demonstrated that inhibition of ODC's enzymatic activity and down-regulation of its expression are rational strategies for both chemotherapy and chemoprevention. Specific inhibitors of ODC, most notably 2-difluoromethylornithine (DFMO), have been used experimentally to validate polyamine metabolism as an antineoplastic strategy. However, multiple biochemical and clinical limitations to these ODC-targeting strategies minimize their value as therapeutic tools. Included among these limitations are poor bioavailability of the inhibitor, and the compensatory up-regulation of polyamine metabolism and transport that allow tumor cells to escape the growth inhibitory effects of blockers specifically targeting ODC. As a strategy to overcome the limitations of direct enzyme inhibition, several groups have pursued the design of polyamine analogues that specifically target the dysregulated polyamine metabolism found in tumors. These analogues have been developed specifically to target the specific polyamine transporter, thus competing with circulating natural polyamines. Additionally, most of the analogues examined thus far maintain the regulatory function of the natural polyamines, but are unable to functionally substitute for them in promoting growth. Specifically, individual analogues have demonstrated the ability to down-regulate each of the biosynthetic enzymes without causing

  1. Natural aphrodisiacs.

    PubMed

    Shamloul, Rany

    2010-01-01

    The search for a remedy or a prescription that can enhance sexual function and/or treat male erectile dysfunction has been an obsession throughout known history. Whether it was an Eastern civilization or a Western one, religious or atheist, man's aspiration for a better or best "manhood" has been a history-time goal. This review will discuss the current research done on the most popular natural aphrodisiacs and examine the weight of evidence to support or discourage the use of any of these substances to enhance sexual desire and/or function. Review of the current evidence on the use of natural substances as aphrodisiacs. Efficacy of natural aphrodisiacs in enhancing sexual function in men and women. There is little evidence from literature to recommend the usage of natural aphrodisiacs for the enhancement of sexual desire and/or performance. Data on yohimbine's efficacy does not support the wide use of the drug, which has only mild effects in the treatment of psychogenic ED. Although there's a positive trend towards recommending ginseng as an effective aphrodisiac, however, more in depth studies involving large number of subjects and its mechanism of action are needed before definite conclusions could be reached. Data on the use of natural aphrodisiacs in women is limited. The current body of objective evidence does not support the use of any natural aphrodisiac as an effective treatment for male or female sexual dysfunctions. Potent men and men with ED will continue the search for natural aphrodisiacs despite the current disappointing data on their effectiveness. Care should be taken regarding the fraud addition of sildenafil analogues to natural aphrodisiacs.

  2. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  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. GABAA Receptor Modulation by Etomidate Analogues

    PubMed Central

    Pejo, Ervin; Santer, Peter; Wang, Lei; Dershwitz, Philip; Husain, S. Shaukat; Raines, Douglas E.

    2015-01-01

    Background Etomidate is a highly potent anesthetic agent that is believed to produce hypnosis by enhancing γ-aminobutyric acid type A (GABAA) receptor function. We characterized the GABAA receptor and hypnotic potencies of etomidate analogues. We then used computational techniques to build statistical and graphical models that relate the potencies of these etomidate analogues to their structures in order to identify the specific molecular determinants of potency. Methods GABAA receptor potencies were defined with voltage-clamp electrophysiology using α1β3γ2 receptors harboring a channel mutation (α1(L264T)) that enhances anesthetic sensitivity (n = 36 – 60 measurements per concentration-response curve). The hypnotic potencies of etomidate analogues were defined using a loss of righting reflexes assay in Sprague Dawley rats (n = 9 – 21 measurements per dose-response curve). Three-dimensional quantitative structure-activity relationships were determined in silico using comparative molecular field analysis. Results The GABAA receptor and hypnotic potencies of etomidate and the etomidate analogues ranged by 91-fold and 53-fold, respectively. These potency measurements were significantly correlated (r2 = 0.72), but neither measurement correlated with drug hydrophobicity (r2 = 0.019 and 0.005, respectively). Statistically significant and predictive comparative molecular field analysis models were generated and a pharmacophore model was built that revealed both the structural elements in etomidate analogues associated with high potency and the interactions that these elements make with the etomidate binding site. Conclusion There are multiple specific structural elements in etomidate and etomidate analogues that mediate GABAA receptor modulation. Modifying any one element can alter receptor potency by an order of magnitude or more. PMID:26691905

  6. Total Synthesis and Evaluation of Phostriecin and Key Structural Analogues

    PubMed Central

    Burke, Christopher P.; Swingle, Mark R.; Honkanen, Richard E.; Boger, Dale L.

    2010-01-01

    Full details of the total synthesis of phostriecin (2), the assignment of its relative and absolute stereochemistry, and the resultant structural reassignment of the natural product previously represented as sultriecin (1), a phosphate versus sulfate monoester, are detailed. Studies with authentic material confirmed that phostriecin, but not sultriecin, is an effective and selective inhibitor of protein phosphatase 2A (PP2A) defining a mechanism of action responsible for its antitumor activity. The extension of the studies to the synthesis and evaluation of a series of key synthetic analogues is disclosed that highlights the importance of the natural product phosphate monoester (vs sulfate or free alcohol, inactive and >250-fold), the α,β-unsaturated lactone (12-fold), and the hydrophobic Z,Z,E-triene tail (C12–C22, ca. 200-fold) including the unique importance of its unsaturation (50-fold, and no longer PP2A selective). PMID:20669916

  7. New optimized piperamide analogues with potent in vivo hypotensive properties.

    PubMed

    de Mattos Duarte, Carolina; Verli, Hugo; de Araújo-Júnior, João Xavier; de Medeiros, Isac Almeida; Barreiro, Eliezer J; Fraga, Carlos Alberto Manssour

    2004-12-01

    We describe herein the structural optimization of new piperamide analogues, designed from two natural prototypes, piperine 1 and piperdardine 2, obtained from Piper tuberculatum Jacq. (Piperaceae). Molecular modeling studies using semiempirical AM1 method were made in order to establish rational modifications to optimize them by molecular simplification. The targeted compounds (10) and (11) were respectively obtained using benzaldehyde (12) and para-anisaldehyde (13) as starting materials. 1H NMR spectra showed that the target compounds were diastereoselectively obtained as the (E)-isomer, the same geometry of the natural prototypes. These new synthetic amides presented significant hypotensive effects in cardiovascular essays using in vivo methodologies. Compound 11 (N-[5-(4'-methoxyphenyl)-2(E)-pentenoyl]thiomorpholine) showed a potency 10,000 times greater than its prototype 5, evidencing an optimization of the molecular architecture for this class of hypotensive drug candidates.

  8. New camptothecin and ellagic acid analogues from the root bark of Camptotheca acuminata.

    PubMed

    Zhang, Zhizhen; Li, Shiyou; Zhang, Shanmin; Liang, Chun; Gorenstein, David; Beasley, R Scott

    2004-12-01

    As part of a study on chemical constituents of Camptotheca species, one new natural camptothecin analogue (2), two new alkaloids (3, 4), one new ellagic acid analogue (5), and 19 known compounds (1, 6-23) have been isolated from the root bark, stem bark, fruits, and leaves of Camptotheca acuminata Decaisne. The structures of 2-5 were determined from spectral data to be 10-methoxy-20-O-acetylcamptothecin (2), 20-O-beta-glucopyranosyl 18-hydroxycamptothecin (3), 20-formylbenz indolizino [1,2-b]quino-line-11(13H)-one (4), and 3,4-methylenedioxy-3'-O-methyl-5'-hydroxyellagic acid (5).

  9. Synthesis and Bioactivity of a Brasilicardin A Analogue Featuring a Simplified Core.

    PubMed

    Jung, Michael E; Chamberlain, Brian T; Koch, Pierre; Niazi, Kayvan R

    2015-07-17

    An analogue 2 of Brasilicardin A, 1 (BraA), a potent immunosuppressive and cytotoxic agent, was synthesized in which the natural tricyclic skeleton was replaced with a synthetically more accessible substituted tetrahydronaphthalene core. BraA, this analogue (BraL), and cyclosporine A were tested for their ability to inhibit the proliferation of human T cells upon CD3/CD28 activation. Although BraL did not impact T cell activation over the dose range tested, this study shows the inhibitory activity of BraA on human T cells for the first time.

  10. 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.

  11. Insulin analogues: action profiles beyond glycaemic control.

    PubMed

    Eckardt, Kristin; Eckel, Jürgen

    2008-02-01

    A variety of studies have documented significant improvements in the treatment of type 1 and 2 diabetes after the introduction of artificial insulins. This review gives an overview of insulin analogues which are currently approved for therapeutical use. Clinical data regarding the efficiency to control blood glucose level as well as improving HbA1c level in comparison to conventional insulin preparations in type 1 and 2 diabetic patients are summarized. Furthermore, special features of insulin analogues regarding their signalling properties are discussed with focus on the proliferative effects of insulin glargine as well as some recent data of insulin detemir.

  12. 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.

  13. 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

  14. 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.

  15. Facile polymerization of dNTPs bearing unnatural base analogues by DNA polymerase alpha and Klenow fragment (DNA polymerase I).

    PubMed

    Chiaramonte, Molly; Moore, Chad L; Kincaid, Kristi; Kuchta, Robert D

    2003-09-09

    The high fidelity of DNA replication is largely dependent upon accurate incorporation of dNTPs by DNA polymerases. To study the mechanism underlying nucleotide selection, we synthesized four nucleotide analogues bearing the unnatural bases benzimidazole, 5-nitrobenzimidazole, 6-nitrobenzimidazole, and 5-nitroindole and analyzed their incorporation by three DNA polymerases. We have found that human DNA polymerase alpha (pol alpha) and the Klenow fragment of Escherichia coli DNA polymerase I (KF) incorporate all four nucleotide analogues opposite all four canonical bases up to 4000-fold more efficiently than an incorrect natural dNTP (i.e., rates that approach those of a correct, natural dNTP), even though the shape of any base pair formed between the analogue and the template likely does not resemble a normal base pair. While pol alpha preferentially incorporated the analogues opposite template pyrimidines, KF surprisingly preferred to polymerize them opposite template purines. Although neither pol alpha nor KF readily polymerized a natural dNTP opposite either 5- or 6-nitrobenzimidazole in the template strand, the enzymes did incorporate the analogues to generate novel base pairs. Both pol alpha and KF polymerized the analogues up to 140-fold more efficiently than dATP both across from abasic sites and as 3'-overhangs on blunt-ended templates. Although Maloney murine leukemia virus reverse transcriptase did not measurably incorporate the analogues, this enzyme bound the analogues with K(I)'s only slightly higher than the K(m) for polymerization of the normal dNTP. The implications of these results with respect to how polymerases discriminate between correct and incorrect dNTPs are discussed.

  16. Migrastatin Analogues Inhibit Canine Mammary Cancer Cell Migration and Invasion

    PubMed Central

    Majchrzak, Kinga; Lo Re, Daniele; Gajewska, Małgorzata; Bulkowska, Małgorzata; Homa, Agata; Pawłowski, Karol; Motyl, Tomasz; Murphy, Paul V.; Król, Magdalena

    2013-01-01

    Background Cancer spread to other organs is the main cause of death of oncological patients. Migration of cancer cells from a primary tumour is the crucial step in the complex process of metastasis, therefore blocking this process is currently the main treatment strategy. Metastasis inhibitors derived from natural products, such as, migrastatin, are very promising anticancer agents. Thus, the aim of our study was to investigate the effect of six migrastatin analogues (MGSTA-1 to 6) on migration and invasion of canine mammary adenocarcinoma cell lines isolated from primary tumours and their metastases to the lungs. Canine mammary tumours constitute a valuable tool for studying multiple aspect of human cancer. Results Our results showed that two of six fully synthetic analogues of migrastatin: MGSTA-5 and MGSTA-6 were potent inhibitors of canine mammary cancer cells migration and invasion. These data were obtained using the wound healing test, as well as trans-well migration and invasion assays. Furthermore, the treatment of cancer cells with the most effective compound (MGSTA-6) disturbed binding between filamentous F-actin and fascin1. Confocal microscopy analyses revealed that treatment with MGSTA-6 increased the presence of unbound fascin1 and reduced co-localization of F-actin and fascin1 in canine cancer cells. Most likely, actin filaments were not cross-linked by fascin1 and did not generate the typical filopodial architecture of actin filaments in response to the activity of MGSTA-6. Thus, administration of MGSTA-6 results in decreased formation of filopodia protrusions and stress fibres in canine mammary cancer cells, causing inhibition of cancer migration and invasion. Conclusion Two synthetic migrastatin analogues (MGSTA-5 and MGSTA-6) were shown to be promising compounds for inhibition of cancer metastasis. They may have beneficial therapeutic effects in cancer therapy in dogs, especially in combination with other anticancer drugs. However, further in

  17. 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

  18. 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.

  19. Dicentrine Analogue-Induced G2/M Arrest and Apoptosis through Inhibition of Topoisomerase II Activity in Human Cancer Cells.

    PubMed

    Lin, Huei-Fang; Huang, Huey-Lan; Liao, Jyh-Fei; Shen, Chien-Chang; Huang, Ray-Ling

    2015-07-01

    Lindera megaphylla has been traditionally used as an antineoplastic and wound healing remedy. We previously demonstrated the antitumor effects of D-dicentrine, a natural aporphine alkaloid from the root of L. megaphylla. To generate analogues, series of phenanthrene alkaloids from D-dicentrine were synthesized by degradation with ethyl chloroformate in pyridine, base hydrolysis, and N-alkylation. In this study, we demonstrated that one of the synthesized D-dicentrine analogues (here after designated as analogue 1) exhibited more potent cytotoxic effects than D-dicentrine in colon adenocarcinoma, hepatoma, leukemia, and epidermoid carcinoma cells. We performed cell cycle and apoptotic analysis by flow cytometry, an apoptotic DNA detection ELISA assay, and topoisomerase II activity by the kinetoplast DNA concatenation assay for studying their cytotoxic mechanisms. We found that both D-dicentrine and analogue 1 induced apoptosis and G2/M arrest in HL-60 leukemia cells. The percentage of apoptotic cells induced by analogue 1 was 4.5-fold higher than that induced by D-dicentrine as evident from measuring the amount of histone-bound DNA fragments. Moreover, we found that analogue 1 was 28-fold more potent than D-dicentrine for inhibition of topoisomerase II activity by the kinetoplast DNA concatenation assay. Our findings indicate that D-dicentrine analogue 1 is very promising as a potential antitumor agent for future study.

  20. Geochemical applications for prompt gamma neutron activation

    NASA Astrophysics Data System (ADS)

    Glascock, M. D.; Coveney, R. M.; Tittle, C. W.; Gartner, M. L.; Murphy, R. D.

    1985-05-01

    Neutron-capture (prompt) gamma-ray neutron activation techniques are finding increasing application for both laboratory and in situ measurement of geological materials. Prompt gamma rays can be used to measure abundances for most light mass elements and several heavier mass elements which are more difficult by other techniques. These elements include many of those routinely measured in rocks and minerals. Geochemical abundance data provide information useful for determining rock and ore genesis, porosity, moisture content, salinity, and the detection of formerly oxidizing or reducing environments. Some of the applications include development of petrogenetic models, exploration and development of oil and mineral deposits, and process control in the mining industry.

  1. DNA-based methods of geochemical prospecting

    DOEpatents

    Ashby, Matthew [Mill Valley, CA

    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.

  2. Remote detection of geochemical soil anomalies

    USGS Publications Warehouse

    Canney, F.C.

    1970-01-01

    This paper describes a preliminary experiment that was made to compare the spectral reflectance from trees growing in soil over a mineral deposit with reflectance from trees of the same species growing in a nearby unmineralized area. Although the measurements were made on a relatively small number of trees, some significant differences were obtained and the over-all results are encouraging enough to warrant additional studies. Preliminary results suggest that measurement of spectral reflectance may become a dramatic new way of detecting geochemical soil anomalies by remote means in tree-covered areas.

  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. Component-based syntheses of trioxacarcin A, DC-45-A1 and structural analogues

    NASA Astrophysics Data System (ADS)

    Magauer, Thomas; Smaltz, Daniel J.; Myers, Andrew G.

    2013-10-01

    The trioxacarcins are polyoxygenated, structurally complex natural products that potently inhibit the growth of cultured human cancer cells. Here we describe syntheses of trioxacarcin A, DC-45-A1 and structural analogues by late-stage stereoselective glycosylation reactions of fully functionalized, differentially protected aglycon substrates. Key issues addressed in this work include the identification of an appropriate means to activate and protect each of the two 2-deoxysugar components, trioxacarcinose A and trioxacarcinose B, as well as a viable sequencing of the glycosidic couplings. The convergent, component-based sequence we present allows for rapid construction of structurally diverse, synthetic analogues that would be inaccessible by any other means, in amounts required to support biological evaluation. Analogues that arise from the modification of four of five modular components are assembled in 11 steps or fewer. The majority of these are found to be active in antiproliferative assays using cultured human cancer cells.

  5. Design, synthesis and cytotoxic evaluation of o-carboxamido stilbene analogues.

    PubMed

    Azmi, Mohamad Nurul; Din, Mohd Fadzli Md; Kee, Chin Hui; Suhaimi, Munirah; Ping, Ang Kheng; Ahmad, Kartini; Nafiah, Mohd Azlan; Thomas, Noel F; Mohamad, Khalit; Hoong, Leong Kok; Awang, Khalijah

    2013-11-27

    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.

  6. Synthesis and conformational analysis of 17alpha,21-cyclo-22-unsaturated analogues of calcitriol.

    PubMed

    Riveiros, Ricardo; Rumbo, Antonio; Sarandeses, Luis A; Mouriño, Antonio

    2007-07-20

    Six new calcitriol analogues, conformationally restricted at their side chain by the introduction of both a cyclopropane ring at C17-C20 and a double or triple bond at C22, were synthesized using the Wittig-Horner approach to construct the triene system. The six CD-ring and side-chain bearing fragments were prepared from ketone 14 by a divergent route to generate both series of epimers at C20, followed by stereoselective cyclopropanation. The (E)-alkenyl side chain was synthesized by means of a Wittig reaction. The alkynyl side chain was prepared by Corey-Fuchs homologation, followed by alkylation. The (Z)-alkenyl side chain was prepared from the previous alkyne by partial hydrogenation. The 20-epi analogues bind more strongly to VDR than the corresponding analogues with the C20 natural stereochemistry. These results can be reasoned by conformational analysis and hydrophobic interactions with the VDR ligand-binding domain.

  7. Design of novel analogues of short antimicrobial peptide anoplin with improved antimicrobial activity.

    PubMed

    Wang, Yang; Chen, Jianbo; Zheng, Xin; Yang, Xiaoli; Ma, Panpan; Cai, Ying; Zhang, Bangzhi; Chen, Yuan

    2014-12-01

    Currently, novel antibiotics are urgently required to combat the emergence of drug-resistant bacteria. Antimicrobial peptides with membrane-lytic mechanism of action have attracted considerable interest. Anoplin, a natural α-helical amphiphilic antimicrobial peptide, is an ideal research template because of its short sequence. In this study, we designed and synthesized a group of analogues of anoplin. Among these analogues, anoplin-4 composed of D-amino acids displayed the highest antimicrobial activity due to increased charge, hydrophobicity and amphiphilicity. Gratifyingly, anoplin-4 showed low toxicity to host cells, indicating high bacterial selectivity. Furthermore, the mortality rate of mice infected with Escherichia coli was significantly reduced by anoplin-4 treatment relative to anoplin. In conclusion, anoplin-4 is a novel anoplin analogue with high antimicrobial activity and enzymatic stability, which may represent a potent agent for the treatment of infection.

  8. 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

  9. 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.

  10. Synthesis of novel 2'-fluoro-3'-hydroxymethyl-5'-deoxythreosyl phosphonic acid nucleoside analogues as antiviral agents.

    PubMed

    Kim, Kyung Mi; Hong, Joon Hee

    2014-01-01

    A series of purine 5'-deoxyphosphonate analogues were designed and synthesized to mimic naturally occurring purine monophosphate from 1,3-dihydroxyacetone as starting material. The discovery of threosyl phosphonate nucleoside (PMDTA, EC50 = 2.53 μM) as a potent anti-HIV agent has led to the synthesis and biological evaluation of 2',3'-modified 5'-deoxyversions of the threosyl phosphonate nucleosides. The synthesized 2'-fluoro-3'-hydroxymethyl 5'-deoxythreosyl phosphonic acid nucleoside analogues 14, 18, 23, and 27 were tested for anti-HIV activity as well as cytotoxicity. The adenine analogue 18 exhibits weak in vitro anti-HIV-1 activity (EC50 = 19.2 μM).

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. Differential Client Attractiveness in a Counseling Analogue

    ERIC Educational Resources Information Center

    Davis, Carl S.; And Others

    1977-01-01

    Investigated variations in conceptual complexity level of counselor and client on counselor attraction to the client. Counselor trainees rated attractiveness of clients following two counseling analogue tasks in which the client was depicted as exhibiting high or low conceptual level. More complex clients are more attractive across both levels.…

  17. 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.

  18. Solanapyrone analogues from a Hawaiian fungicolous fungus

    USDA-ARS?s Scientific Manuscript database

    Four new solanayrone analogues (solanapyrones J-M; 1-4) have been isolated from an unidentified fungicolous fungus collected in Hawaii. The structures and relative configurations of these compounds were determined by analysis of ID NMR, 2D NMR, and MS data. Solanapyrone J(1) showed antifungal acti...

  19. Analoguing Creativity & Culture: A Method for Metaphors.

    ERIC Educational Resources Information Center

    Thompson, Timothy N.

    Adding to the benefits of using metaphors as tools, "analoguing" (a method of analysis that focuses on metaphors for meanings in use and meanings of metaphors in use) helps avoid excessive categorization and separation by looking for unities and patterns in phenomena rather than for divisions. Six months of observation of patte