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Sample records for dynamic speciation analysis

  1. Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME).

    PubMed

    Benhabib, Karim; Town, Raewyn M; van Leeuwen, Herman P

    2009-04-09

    Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the coupled diffusion of free and particle-bound atrazine toward the solid/sample solution interface. In the eventual equilibrium the total atrazine concentration in the solid phase is dictated by the solid phase/water partition coefficient (K(sw)) and the concentration of the free atrazine in the sample solution. These observations demonstrate that the nanoparticles do not enter the solid phase. The experimental data show that the rate of release of sorbed atrazine from the latex particles is fast on the effective time scale of the microextraction process. A lability criterion is derived to quantitatively describe the relative rates of these two processes. All together, the results indicate that SPME has a strong potential for dynamic speciation analysis of organic compounds in media containing sorbing nanoparticles.

  2. Speciation analysis of arsenic and selenium compounds by CE-dynamic reaction cell-ICP-MS.

    PubMed

    Hsieh, Meng-Wei; Liu, Chen-Ling; Chen, Jing-Huan; Jiang, Shiuh-Jen

    2010-07-01

    A dynamic reaction cell ICP-MS was used as a CE detector for the speciation analysis of arsenic and selenium. Samples containing arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, selenite, selenate, selenocysteine, selenomethione, and Se-methylselenocysteine were subjected to electrophoretic separation before being introduced into the microconcentric nebulizer (CEI-100) for their determination by ICP-MS. The separation has been achieved in a 60 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used was 25 mmol/L CAPS, and 0.5 mmol/L SDS at pH 9.5, whereas the applied voltage was set at 25 kV. The potentially interfering (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+) at the selenium masses m/z 78 and 80 were reduced in intensity by approximately three orders of magnitude by using 1.4 mL/min CH(4) as reactive cell gas in the dynamic reaction cell. Arsenic was determined as the adduct ion (75)As(12)CH(2) (+) at m/z 89. The LOD for arsenic and selenium was in the range of 0.6-1.8 ng/mL, and 0.5-1.4 ng/mL, respectively, based on peak height. This method has been applied to determine various arsenic and selenium compounds in NIST SRM 1633a Coal Fly Ash and NRCC DOLT-3 Dogfish Liver reference materials and a selenium dietary supplement. The arsenic and selenium compounds were extracted from fish liver and dietary supplement by using Protease XIV and Lipase, and from coal fly ash with HF solution. The spike recoveries were in the range 91-103% for all the species studied.

  3. The speciation of behavior analysis

    PubMed Central

    Rider, David P.

    1991-01-01

    The relationship between the Experimental Analysis of Behavior (EAB) and Applied Behavior Analysis (ABA) has been the subject of several editorials and commentaries in recent years. Various authors have argued that researchers in these two fields (a) have become isolated from each other, (b) face different requirements for survival in their respective fields, and (c) possess different skills to meet those requirements. The present paper provides an allegory for the relationship between EAB and ABA in terms of biological speciation. The conditions that have changed the relationship between EAB and ABA are parallel to those responsible for biological speciation: (a) isolation of some members of a species from the rest of the population, (b) different contingencies of survival for members of the two separate groups, and (c) divergence in the adaptive characteristics displayed by the two groups. When members of two different groups, descendants of common ancestors, no longer are capable of producing viable offspring by interbreeding, the different groups then represent different species. To the extent that members of the EAB group and members of the ABA group interact with each other only trivially, they each represent allegorically different species. Changes in the relationship between EAB and ABA are part of a natural process that takes place in many other sciences, and the course of that process can hardly be reversed by us. PMID:22478096

  4. Considerations in As analysis and speciation

    USGS Publications Warehouse

    Edwards, M.; Patel, S.; McNeil, L.; Chen, H.W.; Frey, M.; Eaton, A.D.; Antweiler, R.C.; Taylor, H.E.

    1998-01-01

    This article summarizes recent experiences in arsenic (As) quantification, preservation, and speciation developed during AWWA Research Foundation (AWWARF) and Water Industry Technical Action Fund (WITAF) projects. The goal of this article is to alert analysts and decision-makers to potential problems in As analysis and speciation, because there appear to be several unresolved problems with routine analytical approaches. In true split drinking water samples As was quantified by three accepted analytical methods in three laboratories. The techniques used were graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation inductively coupled plasma-emission spectrometry (HG-ICP-AES). Experimental findings are organized into sections on As analysis, particulate As in water supplies, and examination of As speciation methods.

  5. Pervaporation: a useful tool for speciation analysis

    NASA Astrophysics Data System (ADS)

    Luque de Castro, M. D.; Papaefstathiou, I.

    1998-02-01

    The application of pervaporation as both an auxiliary and a fundamental device for speciation analysis in liquid and solid samples is discussed. Examples of various determinations, including the coupling of the technique to both a gas chromatograph and flow-injection configurations, applied mostly to environmental and biological samples, are presented, giving clear evidence of the double role of the pervaporation process.

  6. Biosensor for metal analysis and speciation

    DOEpatents

    Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

    2007-01-30

    A biosensor for metal analysis and speciation is disclosed. The biosensor comprises an electron carrier immobilized to a surface of an electrode and a layer of an immobilized enzyme adjacent to the electrode. The immobilized enzyme comprises an enzyme having biological activity inhibited by a metal to be detected by the biosensor.

  7. ARSENIC SPECIATION ANALYSIS IN HUMAN SALIVA

    EPA Science Inventory

    Background: Determination of arsenic species in human saliva is potentially useful for biomonitoring of human exposure to arsenic and for studying arsenic metabolism. However, there is no report on the speciation analysis of arsenic in saliva. Methods: Arsenic species in saliva ...

  8. Mercury speciation analysis in terrestrial animal tissues.

    PubMed

    Berzas Nevado, J J; Rodríguez Martín-Doimeadios, R C; Guzmán Bernardo, F J; Rodríguez Fariñas, N; Patiño Ropero, M J

    2012-09-15

    No previous analytical procedures are available and validated for mercury speciation analysis in terrestrial animal tissues. This analysis is a difficult task both because the expected concentrations are low, since important accumulation process are not likely to occur, and also because there are not commercially available certified reference material. Thus, an analytical methodology has been developed and validated for mercury speciation for the specific case of terrestrial animal tissues. The proposed method is based on the quantitative extraction of the species by closed-vessel microwave assisted heating with an alkaline reagent, followed by ethylation. The ethylated derivatives were then submitted to head-space solid phase microextraction with a 100 μm polidimethylsiloxane-coated fiber, and desorbed onto a gas chromatograph coupled to atomic fluorescence detection via pyrolysis unit (HS-SPME-GC-pyro-AFS). Procedural detection limits were 31.8 ng g(-1) and 52.5 ng g(-1) for CH(3)Hg(+) and Hg(2+), respectively, for liver and 35.3 ng g(-1) and 58.1 ng g(-1) for CH(3)Hg(+) and Hg(2+), respectively, for kidney. These limits of detection are 5.5 and 6 times better than the obtained without solid phase microextraction for CH(3)Hg(+) and Hg(2+), respectively. The methodology was found linear up to 120 μg L(-1) and reproducible from one day to the following. It was validated with certified reference materials NCS ZC 71001 (beef liver) and BCR No 186 (pig kidney) for total mercury, calculated as the sum of species, and with spiked red deer liver and kidney for speciation. Finally, it was applied to the analysis of samples of red deer liver, red deer kidney and wild boar kidney coming from the Almadén's mercury mining area (Ciudad Real, Spain), the longest and largest producer of mercury in the world until its closure in 2002. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Speciation dynamics and biogeography of Neotropical spiral gingers (Costaceae).

    PubMed

    André, Thiago; Salzman, Shayla; Wendt, Tânia; Specht, Chelsea D

    2016-10-01

    Species can arise via the divisive effects of allopatry as well as due to ecological and/or reproductive character displacement within sympatric populations. Two separate lineages of Costaceae are native to the Neotropics; an early-diverging clade endemic to South America (consisting of ca. 16 species in the genera Monocostus, Dimerocostus and Chamaecostus); and the Neotropical Costus clade (ca. 50 species), a diverse assemblage of understory herbs comprising nearly half of total familial species richness. We use a robust dated molecular phylogeny containing most of currently known species to inform macroevolutionary reconstructions, enabling us to examine the context of speciation in Neotropical lineages. Analyses of speciation rate revealed a significant variation among clades, with a rate shift at the most recent common ancestor of the Neotropical Costus clade. There is an overall predominance of allopatric speciation in the South American clade, as most species display little range overlap. In contrast, sympatry is much higher within the Neotropical Costus clade, independent of node age. Our results show that speciation dynamics during the history of Costaceae is strongly heterogeneous, and we suggest that the Costus radiation in the Neotropics arose at varied geographic contexts. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Microwave-assisted extraction and ion chromatography dynamic reaction cell inductively coupled plasma mass spectrometry for the speciation analysis of arsenic and selenium in cereals.

    PubMed

    Tsai, Chia-Ying; Jiang, Shiuh-Jen

    2011-01-01

    An ion chromatography dynamic reaction cell inductively coupled plasma mass spectrometric (IC-DRC-ICP-MS) method for the speciation of arsenic and selenium compounds is described. Chromatographic separation was performed in a gradient elution mode using 0.5 mmol L(-1) ammonium citrate in 1% methanol (pH 4.5) and 15 mmol L(-1) ammonium citrate in 1% methanol (pH 8.0). The potentially interfering (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+) at selenium masses of m/z 78 and 80 were reduced in intensity by approximately 3 orders of magnitude by using 1.0 mL min(-1) CH(4) as a reactive cell gas in the DRC. Arsenic was determined as the adduct ion (75)As(12)CH(2)(+) at m/z 89. The detection limits of the procedure were in the ranges of 0.006-0.009 ng As mL(-1) and 0.009-0.03 ng Se mL(-1), respectively. This method has been applied to determine various arsenic and selenium compounds in cereal samples. The accuracy of the method has been verified by comparing the sum of the concentrations of individual species obtained by the present procedure with the total concentration of elements. The arsenic and selenium compounds were quantitatively extracted with a Protease XIV and α-amylase solution in a microwave field at 70°C during a period of 30 min. The spike recoveries were in the range of 94-105% for all determinations.

  11. A novel colorimetric method for field arsenic speciation analysis.

    PubMed

    Hu, Shan; Lu, Jinsuo; Jing, Chuanyong

    2012-01-01

    Accurate on-site determination of arsenic (As) concentration as well as its speciation presents a great environmental challenge especially to developing countries. To meet the need of routine field monitoring, we developed a rapid colorimetric method with a wide dynamic detection range and high precision. The novel application of KMnO4 and CH4N2S as effective As(III) oxidant and As(V) reductant, respectively, in the formation of molybdenum blue complexes enabled the differentiation of As(III) and As(V). The detection limit of the method was 8 microg/L with a linear range (R2 = 0.998) of four orders of magnitude in total As concentrations. The As speciation in groundwater samples determined with the colorimetric method in the field were consistent with the results using the high performance liquid chromatography atomic fluorescence spectrometry, as evidenced by a linear correlation in paired analysis with a slope of 0.9990-0.9997 (p < 0.0001, n = 28). The recovery of 96%-116% for total As, 85%-122% for As(III), and 88%-127% for As(V) were achieved for groundwater samples with a total As concentration range 100-800 microg/L. The colorimetric result showed that 3.61 g/L As(III) existed as the only As species in a real industrial wastewater, which was in good agreement with the HPLC-AFS result of 3.56 g/L As(III). No interference with the color development was observed in the presence of sulfate, phosphate, silicate, humic acid, and heavy metals from complex water matrix. This accurate, sensitive, and easy-to-use method is especially suitable for field As determination.

  12. Density-dependent speciation alters the structure and dynamics of neutral communities.

    PubMed

    Wang, Shaopeng; Chen, Anping; Pacala, Stephen W; Fang, Jingyun

    2015-05-07

    The neutral theory of biodiversity (NTB) provides an individual-based modeling framework to study eco-evolutionary dynamics. Previous NTB models usually assumed the same per capita rate of speciation across lineages. However, population dynamics may induce macroevolutionary feedbacks that can result in variable per capita speciation rates across lineages. In this paper, with analytical and simulation approaches, we explore how different scenarios of density-dependent speciation may impact the diversity and phylogenetic patterns of neutral communities, and compare the results to predictions of the original NTB model with an invariant speciation rate. Our results show that positive per capita speciation rate-abundance relationships could result in higher species richness and evenness, enhanced stability (evidenced by higher post-disturbance recovery rates and lower temporal variability in species diversity), and higher imbalance in phylogenetic trees. The opposite patterns are predicted when per capita speciation rates decrease with abundance. Particularly, strong negative speciation rate-abundance relationships can generate a positive correlation between phylogenetic age and abundance, which has been observed in Panamanian tree species. Our findings demonstrate the importance of eco-evolutionary feedbacks for understanding long-term diversity and phylogenetic patterns in ecological communities.

  13. Mercury speciation in seafood using isotope dilution analysis: a review.

    PubMed

    Clémens, Stéphanie; Monperrus, Mathilde; Donard, Olivier F X; Amouroux, David; Guérin, Thierry

    2012-01-30

    Mercury is a toxic compound that can contaminate humans through food and especially via fish consumption. Mercury's toxicity depends on the species, with methylmercury being the most hazardous form for humans. Hg speciation analysis has been and remains a widely studied subject because of the potential difficulty of preserving the initial distribution of mercury species in the analysed sample. Accordingly, many analytical methods have been developed and most of them incur significant loss and/or cross-species transformations during sample preparation. Therefore, to monitor and correct artefact formations, quantification by isotope dilution is increasingly used and provides significant added value for analytical quality assurance and quality control. This review presents and discusses the two different modes of application of isotope dilution analysis for elemental speciation (i.e. species-unspecific isotope dilution analysis and species-specific isotope dilution analysis) and the different quantification techniques (i.e. classical and multiple spike isotope dilution analyses). Isotope tracers are thus used at different stages of sample preparation to determine the extent of inter-species transformations and correct such analytical artefacts. Finally, a synthesis of the principal methods used for mercury speciation in seafood using isotope dilution analysis is presented.

  14. Sediment phosphorus speciation and mobility under dynamic redox conditions

    NASA Astrophysics Data System (ADS)

    Parsons, Chris T.; Rezanezhad, Fereidoun; O'Connell, David W.; Van Cappellen, Philippe

    2017-07-01

    Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O2) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N2), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous- and solid-phase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low ( ˜ 2.5 µM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl2 and NaHCO3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h-1 kg-1 indicated the potential for rapid mineralization of organic P (Po), in particular during periods of aeration when the

  15. Analysis and Speciation of Lanthanoides by ICP-MS

    NASA Astrophysics Data System (ADS)

    Telgmann, Lena; Lindner, Uwe; Lingott, Jana; Jakubowski, Norbert

    2016-11-01

    Inductively coupled plasma mass spectrometry (ICP-MS) is based on formation of positively charged atomic ions in a high-frequency inductively coupled Argon plasma at atmospheric pressure. The ions are extracted and transferred from the plasma source into a mass analyzer operated at high vacuum via an interface equipped with a sampling and a skimmer cone. The ions are separated in the mass analyzer according to their charge to mass ratio. The ions are converted at a conversion dynode and are detected by use of a secondary electron multiplier or a Faraday cup. From an analytical point of view, ICP-MS is a well-established method for multi-elemental analysis in particular for elements at trace- and ultra-trace levels. Furthermore, methods based on ICP-MS offer simple quantification concepts, for which usually (liquid) standards are applied, low matrix effects compared to other conventional analytical techniques, and relative limits of detection (LODs) in the low pg g-1 range and absolute LODs down to the attomol range. For these applications, ICP-MS excels by a high sensitivity which is independent of the molecular structure and a wide linear dynamic range. It has found acceptance in various application areas and during the last decade ICP-MS is also more and more applied for detection of rare earth elements particularly in the life sciences. Due to the fact that all molecules introduced into the high temperature of the plasma in the ion source were completely dissociated and broken down into atoms, which are subsequently ionized, all elemental species information is completely lost. However, if the different species are separated before they enter the plasma by using adequate fractionation or separation techniques, then ICP-MS can be used as a very sensitive element-specific detector. We will discuss this feature of ICP-MS in this chapter in more detail at hand of the speciation of gadolinium-containing contrast agents.

  16. Assessing when chromosomal rearrangements affect the dynamics of speciation: implications from computer simulations.

    PubMed

    Feder, Jeffrey L; Nosil, Patrik; Flaxman, Samuel M

    2014-01-01

    Many hypotheses have been put forth to explain the origin and spread of inversions, and their significance for speciation. Several recent genic models have proposed that inversions promote speciation with gene flow due to the adaptive significance of the genes contained within them and because of the effects inversions have on suppressing recombination. However, the consequences of inversions for the dynamics of genome wide divergence across the speciation continuum remain unclear, an issue we examine here. We review a framework for the genomics of speciation involving the congealing of the genome into alternate adaptive states representing species ("genome wide congealing"). We then place inversions in this context as examples of how genetic hitchhiking can potentially hasten genome wide congealing. Specifically, we use simulation models to (i) examine the conditions under which inversions may speed genome congealing and (ii) quantify predicted magnitudes of these effects. Effects of inversions on promoting speciation were most common and pronounced when inversions were initially fixed between populations before secondary contact and adaptation involved many genes with small fitness effects. Further work is required on the role of underdominance and epistasis between a few loci of major effect within inversions. The results highlight five important aspects of the roles of inversions in speciation: (i) the geographic context of the origins and spread of inversions, (ii) the conditions under which inversions can facilitate divergence, (iii) the magnitude of that facilitation, (iv) the extent to which the buildup of divergence is likely to be biased within vs. outside of inversions, and (v) the dynamics of the appearance and disappearance of exceptional divergence within inversions. We conclude by discussing the empirical challenges in showing that inversions play a central role in facilitating speciation with gene flow.

  17. Trace-Level Automated Mercury Speciation Analysis

    PubMed Central

    Taylor, Vivien F.; Carter, Annie; Davies, Colin; Jackson, Brian P.

    2011-01-01

    An automated system for methyl Hg analysis by purge and trap gas chromatography (GC) was evaluated, with comparison of several different instrument configurations including chromatography columns (packed column or capillary), detector (atomic fluorescence, AFS, or inductively coupled plasma mass spectrometry, ICP-MS, using quadrupole and sector field ICP- MS instruments). Method detection limits (MDL) of 0.042 pg and 0.030 pg for CH3Hg+ were achieved with the automated Hg analysis system configured with AFS and ICPMS detection, respectively. Capillary GC with temperature programming was effective in improving resolution and decreasing retention times of heavier Hg species (in this case C3H7Hg+) although carryover between samples was increased. With capillary GC, the MDL for CH3Hg+ was 0.25 pg for AFS detection and 0.060 pg for ICP-MS detection. The automated system was demonstrated to have high throughput (72 samples analyzed in 8 hours) requiring considerably less analyst time than the manual method for methyl mercury analysis described in EPA 1630. PMID:21572543

  18. Speciation reversal and biodiversity dynamics with hybridization in changing environments.

    PubMed

    Seehausen, Ole; Takimoto, Gaku; Roy, Denis; Jokela, Jukka

    2008-01-01

    A considerable fraction of the world's biodiversity is of recent evolutionary origin and has evolved as a by-product of, and is maintained by, divergent adaptation in heterogeneous environments. Conservationists have paid attention to genetic homogenization caused by human-induced translocations (e.g. biological invasions and stocking), and to the importance of environmental heterogeneity for the ecological coexistence of species. However, far less attention has been paid to the consequences of loss of environmental heterogeneity to the genetic coexistence of sympatric species. Our review of empirical observations and our theoretical considerations on the causes and consequences of interspecific hybridization suggest that a loss of environmental heterogeneity causes a loss of biodiversity through increased genetic admixture, effectively reversing speciation. Loss of heterogeneity relaxes divergent selection and removes ecological barriers to gene flow between divergently adapted species, promoting interspecific introgressive hybridization. Since heterogeneity of natural environments is rapidly deteriorating in most biomes, the evolutionary ecology of speciation reversal ought to be fully integrated into conservation biology.

  19. A Multivariate Dynamic Spatial Factor Model for Speciated Pollutants and Adverse Birth Outcomes.

    PubMed

    Kaufeld, Kimberly A; Fuentes, Montse; Reich, Brian J; Herring, Amy H; Shaw, Gary M; Terres, Maria A

    2017-09-11

    Evidence suggests that exposure to elevated concentrations of air pollution during pregnancy is associated with increased risks of birth defects and other adverse birth outcomes. While current regulations put limits on total PM2.5 concentrations, there are many speciated pollutants within this size class that likely have distinct effects on perinatal health. However, due to correlations between these speciated pollutants, it can be difficult to decipher their effects in a model for birth outcomes. To combat this difficulty, we develop a multivariate spatio-temporal Bayesian model for speciated particulate matter using dynamic spatial factors. These spatial factors can then be interpolated to the pregnant women's homes to be used to model birth defects. The birth defect model allows the impact of pollutants to vary across different weeks of the pregnancy in order to identify susceptible periods. The proposed methodology is illustrated using pollutant monitoring data from the Environmental Protection Agency and birth records from the National Birth Defect Prevention Study.

  20. Moran model as a dynamical process on networks and its implications for neutral speciation

    NASA Astrophysics Data System (ADS)

    de Aguiar, Marcus A. M.; Bar-Yam, Yaneer

    2011-03-01

    In population genetics, the Moran model describes the neutral evolution of a biallelic gene in a population of haploid individuals subjected to mutations. We show in this paper that this model can be mapped into an influence dynamical process on networks subjected to external influences. The panmictic case considered by Moran corresponds to fully connected networks and can be completely solved in terms of hypergeometric functions. Other types of networks correspond to structured populations, for which approximate solutions are also available. This approach to the classic Moran model leads to a relation between regular networks based on spatial grids and the mechanism of isolation by distance. We discuss the consequences of this connection for topopatric speciation and the theory of neutral speciation and biodiversity. We show that the effect of mutations in structured populations, where individuals can mate only with neighbors, is greatly enhanced with respect to the panmictic case. If mating is further constrained by genetic proximity between individuals, a balance of opposing tendencies takes place: increasing diversity promoted by enhanced effective mutations versus decreasing diversity promoted by similarity between mates. Resolution of large enough opposing tendencies occurs through speciation via pattern formation. We derive an explicit expression that indicates when speciation is possible involving the parameters characterizing the population. We also show that the time to speciation is greatly reduced in comparison with the panmictic case.

  1. Importance of ICPMS for speciation analysis is changing: future trends for targeted and non-targeted element speciation analysis.

    PubMed

    Feldmann, Joerg; Raab, Andrea; Krupp, Eva M

    2017-07-22

    This article is aimed at researchers interested in organic molecules which contain a heteroatom but who have never considered using inductively coupled plasma mass spectrometry (ICPMS) or who have used ICPMS for years and developed numerous methods for analysis of target elemental species. We try to illustrate (1) that ICPMS has been very useful for speciation analysis of metal(loid) target species and that there is now a trend to replace the costly detector with cheaper detection systems for routine target analysis, and (2) that ICPMS has been used and will be used even more in the future for non-targeted analysis of elements which are not normally associated with ICPMS analysis, such as non-metals such as sulfur, phosphorus, chlorine and fluorine. Graphical Abstract Starting with HPLC-ICPMS for non-targeted analysis of heteroatom containing molecules, once target molecule is identified alternative detectors can be used for routine measurements.

  2. Comparison of gas chromatographic hyphenated techniques for mercury speciation analysis.

    PubMed

    Nevado, J J Berzas; Martín-Doimeadios, R C Rodríguez; Krupp, E M; Bernardo, F J Guzmán; Fariñas, N Rodríguez; Moreno, M Jiménez; Wallace, D; Ropero, M J Patiño

    2011-07-15

    In this study, we evaluate advantages and disadvantages of three hyphenated techniques for mercury speciation analysis in different sample matrices using gas chromatography (GC) with mass spectrometry (GC-MS), inductively coupled plasma mass spectrometry (GC-ICP-MS) and pyrolysis atomic fluorescence (GC-pyro-AFS) detection. Aqueous ethylation with NaBEt(4) was required in all cases. All systems were validated with respect to precision, with repeatability and reproducibility <5% RSD, confirmed by the Snedecor F-test. All methods proved to be robust according to a Plackett-Burnham design for 7 factors and 15 experiments, and calculations were carried out using the procedures described by Youden and Steiner. In order to evaluate accuracy, certified reference materials (DORM-2 and DOLT-3) were analyzed after closed-vessel microwave extraction with tetramethylammonium hydroxide (TMAH). No statistically significant differences were found to the certified values (p=0.05). The suitability for water samples analysis with different organic matter and chloride contents was evaluated by recovery experiments in synthetic spiked waters. Absolute detection and quantification limits were in the range of 2-6 pg for GC-pyro-AFS, 1-4 pg for GC-MS, with 0.05-0.21 pg for GC-ICP-MS showing the best limits of detection for the three systems employed. However, all systems are sufficiently sensitive for mercury speciation in environmental samples, with GC-MS and GC-ICP-MS offering isotope analysis capabilities for the use of species-specific isotope dilution analysis, and GC-pyro-AFS being the most cost effective alternative.

  3. Hybrid flow system for automatic dynamic fractionation and speciation of inorganic arsenic in environmental solids.

    PubMed

    Zhang, Yanlin; Miró, Manuel; Kolev, Spas D

    2015-03-03

    An integrated flow analysis system and protocol are proposed for the first time for automatic dynamic flow-through fractionation of inorganic arsenic (arsenite and arsenate) in environmental solids in combination with its real-time speciation. Four extractants (i.e., (1) 0.05 M ammonium sulfate, (2) 0.05 M ammonium dihydrogen phosphate, (3) 0.2 M ammonium oxalate, and (4) a mixture of 0.2 M ammonium oxalate and 0.1 M ascorbic acid at 96 °C) are applied sequentially to the sample to measure bioaccessible inorganic arsenic associated with (1) nonspecifically sorbed phases, (2) specifically sorbed phases, (3) amorphous plus poorly crystalline hydrous oxides of iron and aluminum, and (4) well-crystallized hydrous oxides of Fe and Al, respectively. The kinetic extraction profiles of arsenite and total inorganic arsenic are obtained for each extractant by automatic collection of a given number of its aliquots (subfractions) exposed to the solid sample. Arsenite and total inorganic arsenic in each subfraction are converted to arsine sequentially by hydride generation at pH 4.50 and in 1.14 M hydrochloric acid, respectively. Arsine is absorbed into a potassium permanganate solution, the discoloration of which is related to the concentration of the corresponding arsenic species. The proposed method is successfully validated by analyzing a soil reference material (NIST 2710a) and a sediment sample.

  4. Metal speciation dynamics and bioavailability. 2. Radial diffusion effects in the microorganism range.

    PubMed

    Pinheiro, J P; Van Leeuwen, H P

    2001-03-01

    The free ion activity model for the biouptake of metals from complex media is limited to cases where mass transfer is not flux determining. This paper follows a previous paper (Van Leeuwen, H. P. Environ. Sci. Technol. 1999, 33, 3743) where speciation dynamics and bioavailability of metals are analyzed in terms of bioconversion kinetics and simultaneous metal transport in the medium coupled with dissociation kinetics. Such analysis shows under what conditions labile complex species contribute to the biouptake process or, equivalently, under what conditions the free ion activity model is not obeyed. The present work addresses the theoretical extension of the expressions for the metal flux in the medium by a radial diffusion term so that these are also applicable in the microorganism size range. The transition from macroscopic to microscopic surfaces affects not only the nature of the flux but also the extent of lability of complex species (Van Leeuwen, H. P.; Pinheiro, J. P. J. Electroanal. Chem. 1999, 471, 55), and this can have a dramatic influence on the rate of biouptake of metal ions. Labilities of metal complexes and the ensuing limiting metal fluxes are therefore systematically analyzed for various dimensions of the uptaking surface. Different conditions of bioaffinities and bioconversion capacities are considered, and a number of examples of metal complexes with specified kinetic features are discussed.

  5. Dynamics of aluminum speciation in forest-well drainage waters from the Rhode River watershed, Maryland.

    PubMed

    Bi, S P; An, S Q; Yang, M; Chen, T

    2001-05-01

    This paper reports an investigation of the dynamics of aluminum (Al) speciation in the forest-well waters from study site 110 of the Rhode River watershed, a representative sub-unit of Chesapeake Bay. Seasonal changes of Al speciation are evaluated by a modified MINEQL computer model using chemical equilibrium calculation. It was found that Al-F and Al-Org complexes were the dominate forms, whereas toxic forms of Al3+ and Al-OH were not significant. This indicates that Al toxicity is not very serious in the Rhode River area due to the high concentrations of fluoride and organic materials, even though sometimes pH is very low (approximately 4). Increased H+ or some other associated factors may be responsible for the decline in fish and amphibian population on the watershed.

  6. Donnan membrane approach: from equilibrium to dynamic speciation.

    PubMed

    Marang, Laura; Reiller, Pascal; Pepe, Monique; Benedetti, Marc F

    2006-09-01

    Metal ion toxicity is not simply related to the total concentration but to the free or labile metal ion concentration. One of the techniques that can measure the free metal ion concentration is the Donnan Membrane Technique (DMT). However, this method has limitations in terms of a relatively high detection limit (in relation to typical environmental concentrations) and a long equilibration time. We have therefore developed the Flux Donnan Membrane (FDM) Technique, which is a dynamic modification of the standard DMT with improved detection limits and a more rapid response. We show that experimental calibrations of metal ion transport in the FDM can be used to measure [M]free under conditions of either solution-controlled or membrane-controlled diffusive transport. The FDM was used to measure cobalt binding isotherms by a humic substance over a large range of free Co concentrations and pH.

  7. Liquid phase microextraction for the analysis of trace elements and their speciation

    NASA Astrophysics Data System (ADS)

    Hu, Bin; He, Man; Chen, Beibei; Xia, Linbo

    2013-08-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated.

  8. Arsenic speciation in clinical samples: urine analysis using fast micro-liquid chromatography ICP-MS.

    PubMed

    Morton, Jackie; Leese, Elizabeth

    2011-02-01

    Arsenic speciation is a subject that is developing all the time both from improvements in analytical techniques and from increases in toxicological understanding. Despite speciation methods being widely developed, arsenic speciation is not routinely offered as an analysis in clinical laboratory. The work in this paper describes a simple routine method for arsenic speciation that could be easily implemented in clinical laboratories. The method described, a new, fast analytical method for arsenic speciation, is reported using micro-liquid chromatography hyphenated to an inductively coupled plasma mass spectrometer (μLC-ICP-MS). The method uses a low-pressure delivery six-port valve with a 5 cm anion exchange column, which allows a fully resolved separation of five arsenic species (arsenobetaine [AB], arsenite [As(3+)], arsenate [As(5+)], mono-methylarsonic acid [MMA(5+)] and dimethylarsinic acid [DMA(5+)]) in urine in just 6 min. This fast analytical method offers an arsenic speciation method that is feasible for a laboratory that does not have the capability for a dedicated arsenic speciation LC-ICP-MS instrument. The micro-LC system is small, easy to install and is fully integrated with the ICP-MS software. The results reported here are from urine samples from 65 workers in a semiconductor work providing a sample for their routine biological monitoring to assess workplace exposure. Control samples from 20 unexposed people were also determined. Results show that the semiconductor workers exhibit very low levels of arsenic in their urine samples, similar to the levels in the controls, and thus are not significantly exposed to arsenic. Care must be taken when interpreting urinary arsenic species results because it is not always possible to differentiate between dietary and other external sources of exposure.

  9. Mercury speciation in fluorescent lamps by thermal release analysis

    SciTech Connect

    Raposo, Claudio; Windmoeller, Claudia Carvalhinho; Durao Junior, Walter Alves

    2003-07-01

    In this work, mercury speciation in phosphorus powder matrices and soda lime glass waste from new and spent fluorescent lamp wastes has been studied by thermo-desorption/atomic absorption spectrometry (TDAAS), X-ray diffraction (XRD), cold vapor-atomic absorption (CV-AAS) and atomic emission spectrometry/inductively coupled plasma (ICP/AES). TDAAS results show the presence of oxidized forms of mercury, i.e., Hg{sup 1+} and Hg{sup 2+}, especially in wastes with high mercury concentration. Such forms are mobile, and therefore represent a potential hazard waste material. Glass TD profiles of spent fluorescent lamps suggested the presence of mercury strongly linked to the matrix, which desorbs only at high temperatures.

  10. Mercury speciation in fluorescent lamps by thermal release analysis.

    PubMed

    Raposo, Cláudio; Windmöller, Cláudia Carvalhinho; Durão, Walter Alves

    2003-01-01

    In this work, mercury speciation in phosphorus powder matrices and soda lime glass waste from new and spent fluorescent lamp wastes has been studied by thermo-desorption/atomic absorption spectrometry (TDAAS), X-ray diffraction (XRD), cold vapor-atomic absorption (CV-AAS) and atomic emission spectrometry/inductively coupled plasma (ICP/AES). TDAAS results show the presence of oxidized forms of mercury, i.e., Hg(1+) and Hg(2+), especially in wastes with high mercury concentration. Such forms are mobile, and therefore represent a potential hazard waste material. Glass TD profiles of spent fluorescent lamps suggested the presence of mercury strongly linked to the matrix, which desorbs only at high temperatures.

  11. Multielemental speciation analysis by advanced hyphenated technique - HPLC/ICP-MS: A review.

    PubMed

    Marcinkowska, Monika; Barałkiewicz, Danuta

    2016-12-01

    Speciation analysis has become an invaluable tool in human health risk assessment, environmental monitoring or food quality control. Another step is to develop reliable multielemental speciation methodologies, to reduce costs, waste and time needed for the analysis. Separation and detection of species of several elements in a single analytical run can be accomplished by high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS). Our review assembles articles concerning multielemental speciation determination of: As, Se, Cr, Sb, I, Br, Pb, Hg, V, Mo, Te, Tl, Cd and W in environmental, biological, food and clinical samples analyzed with HPLC/ICP-MS. It addresses the procedures in terms of following issues: sample collection and pretreatment, selection of optimal conditions for elements species separation by HPLC and determination using ICP-MS as well as metrological approach. The presented work is the first review article concerning multielemental speciation analysis by advanced hyphenated technique HPLC/ICP-MS. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Comparative transcriptome analysis of chemosensory genes in two sister leaf beetles provides insights into chemosensory speciation.

    PubMed

    Zhang, Bin; Zhang, Wei; Nie, Rui-E; Li, Wen-Zhu; Segraves, Kari A; Yang, Xing-Ke; Xue, Huai-Jun

    2016-12-01

    Divergence in chemosensory traits has been posited as an important component of chemosensory speciation in insects. In particular, chemosensory genes expressed in the peripheral sensory neurons are likely to influence insect behaviors such as preference for food, oviposition sites, and mates. Despite their key role in insect behavior and potentially speciation, the underlying genetic basis for divergence in chemosensory traits remains largely unexplored. One way to ascertain the role of chemosensory genes in speciation is to make comparisons of these genes across closely related species to detect the genetic signatures of divergence. Here, we used high throughput transcriptome analysis to compare chemosensory genes of the sister leaf beetles species Pyrrhalta maculicollis and P. aenescens, whose sexual isolation and host plant preference are mediated by divergent chemical signals. Although there was low overall divergence between transcriptome profiles, there were a number of genes that were differentially expressed between the species. Furthermore, we also detected two chemosensory genes under positive selection, one of which that was also differentially expressed between the species, suggesting a possible role for these genes in chemical-based premating reproductive isolation and host use. Combined with the available chemical and ecological work in this system, further studies of the divergent chemosensory genes presented here will provide insight into the process of chemosensory speciation among Pyrrhalta beetles.

  13. [Study on elemental speciation analysis and transference characteristics of Arnebia euthroma (Royle) Johnst by ICP-MS].

    PubMed

    Shi, Yu-feng; Xie, Ming-yong; Nie, Shao-ping; Jing, Miao; Wang, Xiao-ru

    2007-02-01

    The elemental transference characteristics and primary speciation analysis of Arnebia euthroma (Royle) Johnst were investigated in the present paper. The results showed: sealed digestion at high temperature was more efficient and thorough than microwave-assisted process (MAP) digestion in the preparation of speciation analysis; Most of the elements analyzed, excluding potassium and zinc, exist in particulate speciation in the plant; The transference characteristics of elements were associated with the polarity of extraction solvents. Contents of all 22 elements basically were directly proportional to the polarity of solvents varying from almost no polarity to strong, especially for 7 elements: magnesium, potassium, calcium, manganese, cobalt, thallium and lead.

  14. Linear Combination Fitting (LCF)-XANES analysis of As speciation in selected mine-impacted materials

    EPA Pesticide Factsheets

    This table provides sample identification labels and classification of sample type (tailings, calcinated, grey slime). For each sample, total arsenic and iron concentrations determined by acid digestion and ICP analysis are provided along with arsenic in-vitro bioaccessibility (As IVBA) values to estimate arsenic risk. Lastly, the table provides linear combination fitting results from synchrotron XANES analysis showing the distribution of arsenic speciation phases present in each sample along with fitting error (R-factor).This dataset is associated with the following publication:Ollson, C., E. Smith, K. Scheckel, A. Betts, and A. Juhasz. Assessment of arsenic speciation and bioaccessibility in mine-impacted materials. Diana Aga, Wonyong Choi, Andrew Daugulis, Gianluca Li Puma, Gerasimos Lyberatos, and Joo Hwa Tay JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, USA, 313: 130-137, (2016).

  15. New method for speciation analysis of aluminium fluoride complexes by HPLC-FAAS hyphenated technique.

    PubMed

    Frankowski, M; Zioła-Frankowska, A; Siepak, J

    2010-03-15

    Speciation analysis of aluminium in the presented system of HPLC-FAAS hyphenated technique lasts 4min. Using the bifunctional column in model analysis and using the calculation methods for modelling using the Mineql program enabled the authors to presume that particular forms will be subjected to elution in the following order: (1) AlF(2)(+) and AlF(4)(-), (2) AlF(2+) and AlF(3)(0) and (3) Al(3+). Based on the obtained results for model solutions, the presented method enables the determination of aluminium fluoride complexes and Al(3+) speciation form. The study compares the tendency of occurrence variability of aluminium fluoride complexes and Al(3+) form, determined based on the results obtained using the HPLC-FAAS hyphenated technique with the trend defined based on the Mineql program calculation method. The method was successfully applied to soil samples. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  16. [The progress in speciation analysis of trace elements by atomic spectrometry].

    PubMed

    Wang, Zeng-Huan; Wang, Xu-Nuo; Ke, Chang-Liang; Lin, Qin

    2013-12-01

    The main purpose of the present work is to review the different non-chromatographic methods for the speciation analysis of trace elements in geological, environmental, biological and medical areas. In this paper, the sample processing methods in speciation analysis were summarized, and the main strategies for non-chromatographic technique were evaluated. The basic principles of the liquid extractions proposed in the published literatures recently and their advantages and disadvantages were discussed, such as conventional solvent extraction, cloud point extraction, single droplet microextraction, and dispersive liquid-liquid microextraction. Solid phase extraction, as a non-chromatographic technique for speciation analysis, can be used in batch or in flow detection, and especially suitable for the online connection to atomic spectrometric detector. The developments and applications of sorbent materials filled in the columns of solid phase extraction were reviewed. The sorbents include chelating resins, nanometer materials, molecular and ion imprinted materials, and bio-sorbents. Other techniques, e. g. hydride generation technique and coprecipitation, were also reviewed together with their main applications.

  17. Application of Hyphenated Techniques in Speciation Analysis of Arsenic, Antimony, and Thallium

    PubMed Central

    Michalski, Rajmund; Szopa, Sebastian; Jabłońska, Magdalena; Łyko, Aleksandra

    2012-01-01

    Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices. PMID:22654649

  18. Stability of Tl(III) in the context of speciation analysis of thallium in plants.

    PubMed

    Sadowska, Monika; Biaduń, Ewa; Krasnodębska-Ostręga, Beata

    2016-02-01

    The paper presents both "good" and "bad" results obtained during speciation analysis of thallium in plant tissues of a hyperaccumulator of this metal. The object was white mustard - Sinapis alba L. In this plant there were found traces of trivalent thallium. The crucial point of this study (especially in the case of so unstable thallium form as Tl(III)) was to prove that the presence of Tl(III) was not caused by the procedure of sample preparation itself, and that the whole analytical method provides reliable results. Choice of the method for conservation of the initial speciation, extraction with the highest efficiency and proving the correctness of the obtained data were the most difficult parts of the presented study. It was found that: both freezing and drying cause significant changes in the speciation of thallium; quantitative analysis could be performed only with fresh tissues of mustard plants; only short-term storage of an extract from fresh plant tissues is possible; the methodology is not the source of thallium (III); only the presence of DTPA can greatly limit the reduction of TI(III) to TI(I) (up to 1-3%); the UV irradiation results in disintegration of TI(III)DTPA in the presence of plant matrix (reduction up to 90%).

  19. Gas and liquid chromatography with inductively coupled plasma mass spectrometry detection for environmental speciation analysis — advances and limitations

    NASA Astrophysics Data System (ADS)

    Szpunar, Joanna; McSheehy, Shona; Połeć, Kasia; Vacchina, Véronique; Mounicou, Sandra; Rodriguez, Isaac; Łobiński, Ryszard

    2000-07-01

    Recent advances in the coupling of gas chromatography (GC) and high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP MS) and their role in trace element speciation analysis of environmental materials are presented. The discussion is illustrated with three research examples concerning the following topics: (i) development and coupling of multicapillary microcolumn GC with ICP MS for speciation of organotin in sediment and biological tissue samples; (ii) speciation of arsenic in marine algae by size-exclusion-anion-exchange HPLC-ICP MS; and (iii) speciation of cadmium in plant cell cultures by size-exclusion HPLC-ICP MS. Particular attention is paid to the problem of signal identification in ICP MS chromatograms; the potential of electrospray MS/MS for this purpose is highlighted.

  20. Capillary microextraction (CME) and its application to trace elements analysis and their speciation.

    PubMed

    Hu, Bin; Zheng, Fei; He, Man; Zhang, Nan

    2009-09-14

    As a solvent-free miniaturized sample preparation technique, capillary microextraction (CME) has been hyphenated with different analytical instruments for trace elements analysis of environmental, biological, food and pharmaceutical samples. This review discusses the fundamentals and recent development of CME, including the theoretical basis, extraction modes (packed, open-tubular and monolithic CME) and capillary materials for CME. The emphasis is placed on the application of CME to trace/ultra-trace elements analysis and their speciation. Existing coating/monolithic materials used for CME are summarized together with a detailed overview of their preparation methods.

  1. Nitrogen speciation and phosphorus fractionation dynamics in a lowland Chalk catchment.

    PubMed

    Yates, C A; Johnes, P J

    2013-02-01

    A detailed analysis of temporal and spatial trends in nitrogen (N) speciation and phosphorus (P) fractionation in the Wylye, a lowland Chalk sub-catchment of the Hampshire Avon, UK is presented, identifying the sources contributing to nutrient enrichment, and temporal variability in the fractionation of nutrients in transit from headwaters to lower reaches of the river. Samples were collected weekly from ten monitoring stations with daily sampling at three further sites over one year, and monthly inorganic N and total reactive P (TRP) concentrations at three of the ten weekly monitoring stations over a ten year period are also presented. The data indicate significant daily and seasonal variation in nutrient fractionation in the water column, resulting from plant uptake of dissolved organic and inorganic nutrient fractions in the summer months, increased delivery of both N and P from diffuse sources in the autumn to winter period and during high flow events, and lack of dilution of point source discharges to the Wylye from septic tank, small package Sewage Treatment Works (STW) and urban Waste Water Treatment Works (WwTW) during the summer low flow period. Weekly data show that contributing source areas vary along the river with headwater N and P strongly influenced by diffuse inorganic N and particulate P fluxes, and SRP and organic-rich point source contributions from STW and WwTW having a greater influence in the lower reaches. Long-term data show a decrease in TRP concentrations at all three monitoring stations, with the most pronounced decrease occurring downstream from Warminster WwTW, following the introduction of P stripping at the works in 2001. Inorganic N demonstrates no statistically significant change over the ten year period of record in the rural headwaters, but an increase in the lower reaches downstream from the WwTW which may be due to urban expansion in the lower catchment.

  2. Parapatric speciation in three islands: dynamics of geographical configuration of allele sharing

    PubMed Central

    Iwasa, Yoh

    2017-01-01

    We studied the time to speciation by geographical isolation for a species living on three islands connected by rare migration. We assumed that incompatibility was controlled by a number of quantitative loci and that individuals differing in loci by more than a threshold did not mix genetically with each other. For each locus, we defined the geographical configuration (GC), which specifies islands with common alleles, and traced the stochastic transitions between different GCs. From these results, we calculated the changes in genetic distances. As a single migration event provides an opportunity for transitions in multiple loci, the GCs of different loci are correlated, which can be evaluated by constructing the stochastic differential equations of the number of loci with different GCs. Our model showed that the low number of incompatibility loci facilitates parapatric speciation and that migrants arriving as a group shorten the waiting time to speciation compared with the same number of migrants arriving individually. We also discuss how speciation rate changes with geographical structure. PMID:28386439

  3. Equilibrium speciation dynamics in a model adaptive radiation of island lizards

    PubMed Central

    Rabosky, Daniel L.; Glor, Richard E.

    2010-01-01

    The relative importance of equilibrium and nonequilibrium processes in shaping patterns of species richness is one of the most fundamental questions in biodiversity studies. If equilibrium processes predominate, then ecological interactions presumably limit species diversity, potentially through diversity dependence of immigration, speciation, and extinction rates. Alternatively, species richness may be limited by the rate at which diversity arises or by the amount of time available for diversification. These latter explanations constitute nonequilibrium processes and can apply only to biotas that are unsaturated or far from diversity equilibria. Recent studies have challenged whether equilibrium models apply to biotas assembled through in situ speciation, as this process may be too slow to achieve steady-state diversities. Here we demonstrate that speciation rates in replicate Caribbean lizard radiations have undergone parallel declines to equilibrium conditions on three of four major islands. Our results suggest that feedback between total island diversity and per-capita speciation rates scales inversely with island area, with proportionately greater declines occurring on smaller islands. These results are consistent with strong ecological controls on species richness and suggest that the iconic adaptive radiation of Caribbean anoles may have reached an endpoint. PMID:21135239

  4. XANES Spectroscopic Analysis of Phosphorus Speciation in Alum-Amended Poultry Litter

    SciTech Connect

    Seiter,J.; Staats-Borda, K.; Ginder-Vogel, M.; Sparks, D.

    2008-01-01

    Aluminum sulfate (alum; Al2(SO4)3{center_dot}14H2O) is used as a chemical treatment of poultry litter to reduce the solubility and release of phosphate, thereby minimizing the impacts on adjacent aquatic ecosystems when poultry litter is land applied as a crop fertilizer. The objective of this study was to determine, through the use of X-ray absorption near edge structure (XANES) spectroscopy and sequential extraction, how alum amendments alter P distribution and solid-state speciation within the poultry litter system. Our results indicate that traditional sequential fractionation procedures may not account for variability in P speciation in heterogeneous animal manures. Analysis shows that NaOH-extracted P in alum amended litters is predominantly organic ({approx}80%), whereas in the control samples, >60% of NaOH-extracted P was inorganic P. Linear least squares fitting (LLSF) analysis of spectra collected of sequentially extracted litters showed that the P is present in inorganic (P sorbed on Al oxides, calcium phosphates) and organic forms (phytic acid, polyphosphates, and monoesters) in alum- and non-alum-amended poultry litter. When determining land application rates of poultry litter, all of these compounds must be considered, especially organic P. Results of the sequential extractions in conjunction with LLSF suggest that no P species is completely removed by a single extractant. Rather, there is a continuum of removal as extractant strength increases. Overall, alum-amended litters exhibited higher proportions of Al-bound P species and phytic acid, whereas untreated samples contained Ca-P minerals and organic P compounds. This study provides in situ information about P speciation in the poultry litter solid and about P availability in alum- and non-alum-treated poultry litter that will dictate P losses to ground and surface water systems.

  5. [Speciation analysis of trace elements Cu, Fe and Zn in serum by flame atomic absorption spectrophotometry].

    PubMed

    Hu, Jun; Chang, Yao-Ming; Gao, Shuang-Bin; Hai, Chun-Xu; Li, Jin-Sheng; Xie, Xiao-Ping

    2008-03-01

    Since biological functions of the elements are generally different, depending on their chemical forms, chemical speciation analysis is really important in metallomics research. Thus, multielement analysis and chemical speciation of the elements in serum were carried out in the present work. A hyphenated technique was developed for high-throughput speciation analysis of the copper, iron and zinc in serum by molecular biology technology and flame atomic absorption spectrophotometry (AAS). Here, Cu, Fe and Zn in serum were classifyied as the forms of combination and non-combination. The serum protein was precipitated by 60% concentration of ethanol under hypothermy. The forms of combination of Cu, Fe and Zn in serum which combined with proteins were in precipitations, and the forms of non-combination of Cu, Fe and Zn in serum, which were free ions, were in supernatant. The total amount of Cu, Fe and Zn in serum and the amount of the forms of non-combination of Cu, Fe and Zn were analyzed by AAS. The amount of the forms of combination of Cu, Fe and Zn was obtained by calculation. The detection limit of Cu in serum by the method is around and 9.84 x 10(-3) microg x mL(-1). For Fe and Zn, the detection limit is about 2.76 x 10(-2) microg x mL(-1) and 1.06 x 10(-3) microg x mL(-1), respectively. The percentage recovery of trace elements Cu, Fe and Zn by the proposed procedure is in the range 95.0%-101.0%, 95.0%-102.0% and 95.0%-103.0%, respectively. The relative standard deviation (RSD) of trace elements Cu, Fe and Zn in the serum is in the range 1.88%-2.26%, 0.56%-1.59% and 0.34%-1.36%, respectively. Speciation of trace elements Cu, Fe and Zn in the serum of SD rat were analyzed by the method.

  6. Speciation analysis of aluminium and aluminium fluoride complexes by HPIC-UVVIS.

    PubMed

    Frankowski, Marcin; Zioła-Frankowska, Anetta

    2010-10-15

    The study presents a new analytical method for speciation analysis in fractionation of aluminium fluoride complexes and free Al(3+) in soil samples. Aluminium speciation was studied in model solutions and soil extract samples by means of high performance ion chromatography (HPIC) with UV-VIS detection using post-column reaction with tiron for the separation and detection of aluminium fluoride complex and Al(3+) forms during one analysis. The paper presents particular stages of the chromatographic process optimization involving selecting the appropriate eluent strength, type of elution or concentration and quantity of derivatization reagent. HPIC was performed on a bifunctional analytical column Dionex IonPac CS5A. The use of gradient elution and the eluents A: 1M NH(4)Cl and B: water acidified to pH of eluent phase, enabled full separation of fluoride aluminium forms as AlF(2)(+), AlF(3)(0), AlF(4)(-) (first signal), AlF(2+) (second signal) and form Al(3+) in a single analytical procedure. The proposed new method HPIC-UVVIS was applied successfully in the quantitative and qualitative analysis of soil samples. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Redox transformation, solid phase speciation and solution dynamics of copper during soil reduction and reoxidation as affected by sulfate availability

    NASA Astrophysics Data System (ADS)

    Fulda, Beate; Voegelin, Andreas; Ehlert, Katrin; Kretzschmar, Ruben

    2013-12-01

    In periodically flooded soils, interactions of Cu with biogenic sulfide formed during soil reduction lead to the precipitation of sparingly soluble Cu-sulfides. In contaminated soils, however, the amounts of Cu can exceed the amount of sulfate available for microbial reduction to sulfide. In laboratory batch experiments, we incubated a paddy soil spiked to ∼4.4 mmol kg-1 (280 mg kg-1) Cu(II) to monitor temporal changes in the concentrations of dissolved Cu and the speciation of solid-phase Cu during 40 days of soil reduction and 28 days of reoxidation as a function of initially available reducible sulfate (0.06, 2.09 or 5.92 mmol kg-1). Using Cu K-edge EXAFS spectroscopy, we found that a large fraction of Cu(II) became rapidly reduced to Cu(I) (23-39%) and Cu(0) (7-17%) before the onset of sulfate reduction. Combination with results from sequential Cu extraction and chromium reducible sulfur (CRS) data suggested that complexation of Cu(I) by reduced organic S groups (Sorg) may be an important process during this early stage. In sulfate-depleted soil, Cu(0) and Cu(I)-Sorg remained the dominant species over the entire reduction period, whereas in soils with sufficient sulfate, initially formed Cu(0) and (remaining) Cu(II) became transformed into Cu-sulfide during continuing sulfate reduction. The formation of Cu(0), Cu(I)-Sorg, and Cu-sulfide led to an effective decrease in dissolved Cu concentrations. Differences in Cu speciation at the end of soil reduction however affected the dynamics of Cu during reoxidation. Whereas Cu(0) was rapidly oxidized to Cu(II), more than half of the S-coordinated Cu fraction persisted over 14 days of aeration. Our results show that precipitation of Cu(0) and complexation of Cu(I) by reduced organic S groups are important processes in periodically flooded soils if sulfide formation is limited by the amount of available sulfate or the duration of soil flooding. The speciation changes of Cu described in this study may also affect the

  8. Speciation Dynamics of Phosphorus during (Hydro)Thermal Treatments of Sewage Sludge.

    PubMed

    Huang, Rixiang; Tang, Yuanzhi

    2015-12-15

    (Hydro)thermal treatments of sewage sludge from wastewater treatment process can significantly reduce waste volume and transform sludge into valuable products such as pyrochar and hydrochar. Given the global concern with phosphorus (P) resource depletion, P recycling/reclamation from or direct soil application of the derived chars can be potential P recycling practices. In order to evaluate P recyclability as well as the selection and optimization of treatment techniques, it is critical to understand the effects of different treatment techniques and conditions on P speciation and distribution. In the present study, we systematically characterized P speciation in chars derived from thermal (i.e., pyrolysis) and hydrothermal treatments of municipal sewage sludge using complementary chemical extraction and nuclear magnetic resonance (NMR) spectroscopy methods. P species in the raw activated sludge was dominated by orthophosphate and long-chain polyphosphates, whereas increased amounts of pyrophosphate and short-chain polyphosphates formed after pyrolysis at 250-600 °C. In contrast, hydrothermal treatments resulted in the production of only inorganic orthophosphate in the hydrochar. In addition to the change of molecular speciation, thermal treatments also altered the physical state and extractability of different P species in the pyrochars from pyrolysis, with both total P and polyphosphate being less extractable with increasing pyrolysis temperature. Results from this study suggest that P speciation and availability in sludge-derived chars are tunable by varying treatment techniques and conditions, and provide fundamental knowledge basis for the design and selection of waste management strategies for better nutrient (re)cycling and reclamation.

  9. Perfluorosulfonated ionomer-modified diffusive gradients in thin films: tool for inorganic arsenic speciation analysis.

    PubMed

    Panther, Jared G; Stillwell, Kathryn P; Powell, Kipton J; Downard, Alison J

    2008-12-15

    A new concept in speciation analysis based on the diffusive gradients in thin films (DGT) technique is described. By use of two sets of DGT devices, one set with perfluorosulfonated ionomer (Nafion) diffusive membranes and the other with polyacrylamide, anionic and uncharged analytes can be fractionated on the basis of charge. The dual device method is applied to speciation analysis of dissolved inorganic arsenic species. Over the environmentally significant pH range, inorganic As(III) exists as neutral H(3)AsO(3), whereas As(V) is present as anionic H(2)AsO(4)(-) and HAsO(4)(2-). The measured diffusion coefficient of As(III) through the negatively charged Nafion membrane is significantly larger than that of the As(V) species, whereas diffusion rates are similar through polyacrylamide diffusive gels. Hence, after simultaneously deploying DGT devices with and without Nafion membranes, measurement of the amount of accumulated As in each type of device enables the concentration of both oxidation states to be determined.

  10. Microwave-enhanced cold vapor generation for speciation analysis of mercury by atomic fluorescence spectrometry.

    PubMed

    Wu, Li; Long, Zhou; Liu, Liwei; Zhou, Qin; Lee, Yong-Ill; Zheng, Chengbin

    2012-05-30

    A new and simple cold vapor generation technique utilizing microwave irradiation coupled with atomic fluorescence spectrometry is developed for the speciation analysis of mercury in biological and geological samples. In the presence of formic acid, inorganic mercury (Hg(2+)) and total mercury (both Hg(2+) and methylmercury (MeHg)) can be converted to mercury cold vapor (Hg(0)) by microwave irradiation without and with H(2)O(2), respectively. The cold vapor was subsequently released from the liquid phase and rapidly transported to an atomic fluorescence spectrometer for the mercury detection. Optimum conditions for vapor generation as well as interferences from concomitant ions were carefully investigated. The conventionally required evaporation of the remnants of acid or oxidants was avoided because no significant interferences from these substances were observed, and thus analyte loss and potential contamination were minimized. A limit of detection of 0.005 ng mL(-1) for total mercury or inorganic mercury was obtained. A precision of less than 3% (RSD) at 2 μg L(-1) of mercury species was typical. The accuracy of the method was validated by determination of mercury in geological and biological certified reference materials. The speciation analysis of Hg(2+) and MeHg was achieved by controlling the conditions of microwave-enhanced cold vapor generation and validated via determination of Certified Reference Materials DORM-2, DORM-3 and a real river water sample.

  11. Redox speciation and biogeochemical gradients: Assessing spatial niches and monitoring dynamics in natural systems with voltammetric microelectrodes

    NASA Astrophysics Data System (ADS)

    Druschel, G. K.; Lorenson, G. W.; Eastmann, D. A.; Macalady, J. L.

    2005-12-01

    Biogeochemical gradients may be described by the spatial distribution of redox species distributed in water, where overlap of electron donors and acceptors out of equilibrium defines available sources of potential energy and essentially determines possible microbial metabolisms. Observed changes in redox speciation along a gradient associated with microbial biofilms may additionally provide some environmental basis for assessing physiology of sampled microorganisms. Voltammetric microelectrodes have been used in a variety of environments to describe the links between ecology and geochemistry (Luther et al., 2001). Recent work in Yellowstone National Park hydrothermal waters, the Frassassi caves in central Italy (a sulfidic cave system), and Green Lake in New York (a meromictic lake) have expanded our abilities to use microelectrodes for assessing As(III) concentrations and uncovering more details of sulfur speciation in a wide range of natural waters. We are using these data to design redox-specific culture media, make inferences about microbial physiology, constrain biogeochemical gradients over very fine scales, and observe dynamics in biogeochemical systems. Describing microbial communities and the geochemical environments that surround them at appropriate scales is of importance to begin assessing the links between microbial activity and geochemical cycling. Diversity in an environment may be better assessed if we first know how many different geochemical environments there are in that environment and if the microbial ecology in those environments is essentially independent from environments neighboring it. Because microelectrodes measure multiple redox species simultaneously and do so in matter of seconds, they are also useful in monitoring the dynamics of a biogeochemical system, which will be of use in studying the response of communities to perturbation. We will present results showing the characterization of lateral and vertical gradients over different

  12. Speciation and isotope dilution analysis of gadolinium-based contrast agents in wastewater.

    PubMed

    Telgmann, Lena; Wehe, Christoph A; Birka, Marvin; Künnemeyer, Jens; Nowak, Sascha; Sperling, Michael; Karst, Uwe

    2012-11-06

    The fate of Gadolinium (Gd)-based contrast agents for magnetic resonance imaging (MRI) during sewage treatment was investigated. The total concentration of Gd in influent and effluent 2 and 24 h composite samples was determined by means of isotope dilution analysis. The balancing of Gd input and output of a sewage plant over seven days indicated that approximately 10% of the Gd is removed during treatment. Batch experiments simulating the aeration tank of a sewage treatment plant confirmed the Gd complex removal during activated sludge treatment. For speciation analysis of the Gd complexes in wastewater samples, high performance liquid chromatography (HPLC) was hyphenated to inductively coupled plasma sector field mass spectrometry (ICP-SFMS). Separation of the five predominantly used contrast agents was carried out on a new hydrophilic interaction liquid chromatography stationary phase in less than 15 min. A limit of detection (LOD) of 0.13 μg/L and a limit of quantification of 0.43 μg/L could be achieved for the Gd chelates without having to apply enrichment techniques. Speciation analysis of the 24 h composite samples revealed that 80% of the Gd complexes are present as Gd-BT-DO3A in the sampled treatment plant. The day-of-week dependent variation of the complex load followed the variation of the total Gd load, indicating a similar behavior. The analysis of sewage sludge did not prove the presence of anthropogenic Gd. However, in the effluent of the chamber filter press, which was used for sludge dewatering, two of the contrast agents and three other unknown Gd species were observed. This indicates that species transformation took place during anaerobic sludge treatment.

  13. Contact zone dynamics during early stages of speciation in a chorus frog (Pseudacris crucifer)

    PubMed Central

    Stewart, K A; Austin, J D; Zamudio, K R; Lougheed, S C

    2016-01-01

    Characterizing the genetic and behavioural consequences of contact between previously geographically isolated lineages provides insights into the mechanisms underlying diversification and ultimately speciation. The spring peeper (Pseudacris crucifer) is a widespread Nearctic chorus frog with six divergent mitochondrial DNA (mtDNA) lineages, many of which came into secondary contact during the Holocene. We examined genetics, morphology, advertisement calls and female preference for two lineages that began diverging in allopatry in the Pliocene and now overlap in southwestern Ontario, Canada. We found non-coincident clines in mtDNA and nuclear DNA, mirroring directionality of premating isolation barriers. We also found divergence in a range of traits between these two lineages, displacement in male call attributes and female preference for calls of their natal lineage in sympatry. Hybrids were morphologically distinct from both parental lineages, but hybrid male calls were acoustically intermediate. Female hybrids showed asymmetrical preference for Eastern male calls. These results considered together provide evidence of either unidirectional hybridization or selection against hybrids, potentially implying reproductive character displacement. Our work demonstrates the utility of integrated, multi-character approaches to understanding the processes of divergence and the nature of speciation. PMID:26626576

  14. Contact zone dynamics during early stages of speciation in a chorus frog (Pseudacris crucifer).

    PubMed

    Stewart, K A; Austin, J D; Zamudio, K R; Lougheed, S C

    2016-02-01

    Characterizing the genetic and behavioural consequences of contact between previously geographically isolated lineages provides insights into the mechanisms underlying diversification and ultimately speciation. The spring peeper (Pseudacris crucifer) is a widespread Nearctic chorus frog with six divergent mitochondrial DNA (mtDNA) lineages, many of which came into secondary contact during the Holocene. We examined genetics, morphology, advertisement calls and female preference for two lineages that began diverging in allopatry in the Pliocene and now overlap in southwestern Ontario, Canada. We found non-coincident clines in mtDNA and nuclear DNA, mirroring directionality of premating isolation barriers. We also found divergence in a range of traits between these two lineages, displacement in male call attributes and female preference for calls of their natal lineage in sympatry. Hybrids were morphologically distinct from both parental lineages, but hybrid male calls were acoustically intermediate. Female hybrids showed asymmetrical preference for Eastern male calls. These results considered together provide evidence of either unidirectional hybridization or selection against hybrids, potentially implying reproductive character displacement. Our work demonstrates the utility of integrated, multi-character approaches to understanding the processes of divergence and the nature of speciation.

  15. Theoretical models of the influence of genomic architecture on the dynamics of speciation.

    PubMed

    Flaxman, Samuel M; Wacholder, Aaron C; Feder, Jeffrey L; Nosil, Patrik

    2014-08-01

    A long-standing problem in evolutionary biology has been determining whether and how gradual, incremental changes at the gene level can account for rapid speciation and bursts of adaptive radiation. Using genome-scale computer simulations, we extend previous theory showing how gradual adaptive change can generate nonlinear population transitions, resulting in the rapid formation of new, reproductively isolated species. We show that these transitions occur via a mechanism rooted in a basic property of biological heredity: the organization of genes in genomes. Genomic organization of genes facilitates two processes: (i) the build-up of statistical associations among large numbers of genes and (ii) the action of divergent selection on persistent combinations of alleles. When a population has accumulated a critical amount of standing, divergently selected variation, the combination of these two processes allows many mutations of small effect to act synergistically and precipitously split one population into two discontinuous, reproductively isolated groups. Periods of allopatry, chromosomal linkage among loci, and large-effect alleles can facilitate this process under some conditions, but are not required for it. Our results complement and extend existing theory on alternative stable states during population divergence, distinct phases of speciation and the rapid emergence of multilocus barriers to gene flow. The results are thus a step towards aligning population genomic theory with modern empirical studies. © 2014 John Wiley & Sons Ltd.

  16. Episodic chromosomal evolution in Planipapillus (Onychophora: Peripatopsidae): a phylogenetic approach to evolutionary dynamics and speciation.

    PubMed

    Rockman, Matthew V; Rowell, David M

    2002-01-01

    Planipapillus, a clade of onychophorans from southeastern Australia, exhibits substantial chromosomal variation. In the context of a robust phylogeny based on nuclear and mitochondrial sequence data, we evaluate models of chromosomal evolution and speciation that differ in the roles assigned to selection, mutation, and drift. Permutation tests suggest that all chromosome rearrangements in the clade have been centric fusions and, on the basis of parsimony and maximum-likelihood methods with independent estimates of branch lengths, we conclude that at least 31 centric fusions have been fixed in Planipapillus. A likelihood-ratio test approach, which is independent of our point estimates of ancestral states, rejects an evolutionary model in which the mutation rate is constant and centric fusions are effectively neutral. In contrast to the nucleotide sequence data, which are consistent with neutrality and rate constancy, centric fusions in Planipapillus are underdominant, spontaneous fusion rates vary among lineages, or both. We predict an inverse relationship between rates of chromosomal evolution and historical population size. Chromosomal evolution may play a role in speciation in Planipapillus, both by interactions between centric fusions with monobrachial homology and by the accumulation of multiple weakly underdominant fusions.

  17. Study of the contents and speciation of heavy metals in river sediments by factor analysis

    SciTech Connect

    Pardo, R.; Barrado, E.; Castrillejo, Y.; Velasco, M.A.; Vega, M. )

    1993-08-01

    Heavy metals Zn, Cd, Pb, Cu, Ni and Co from two spanish river sediments have been determined by voltammetric techniques, along with % CaCO[sub 3] and % organic matter, and the whole data set examined by means of Factor Analysis, finding a different behaviour of the metals in each river. Heavy metal speciation in the sediments was carried out by using the Tessier's scheme: Zn and Pb were mainly associated to [open quote]reducible phases[close quote], Cd and Cu bound to [open quote]organic matter and sulphides[close quote], and Ni and Co were distributed between the above fractions. The [open quote]residual[close quote] metals were used as pollution indicators from the rivers, finding a similar behaviour to other industrialized river systems.

  18. Selenometabolomics explored by speciation.

    PubMed

    Ogra, Yasumitsu; Anan, Yasumi

    2012-01-01

    Selenium (Se) belongs to the same group as sulfur in the periodic table but possesses certain chemical properties characteristic of a metal. It is an essential element in animals but becomes severely toxic when the amount ingested exceeds the required level. On the other hand, Se is not essential in plants although some plants are Se hyperaccumulators. Se changes into several chemical forms when metabolized. Thus, the identification of selenometabolites would enable us to formulate a metabolic chart of Se. Recently, speciation analysis by hyphenated techniques has contributed immensely to the study of selenometabolomes, i.e., the entirety of selenometabolites. Indeed, speciation has unveiled some unique selenometabolites in biological samples. The aim of this review is to present newly identified selenometabolites in animals and plants by speciation using hyphenated techniques and to delineate the perspectives of Se biology and toxicology from the viewpoint of speciation.

  19. Early and dynamic colonization of Central America drives speciation in Neotropical army ants.

    PubMed

    Winston, Max E; Kronauer, Daniel J C; Moreau, Corrie S

    2017-02-01

    The emergence of the Isthmus of Panama is one of the most important events in recent geological history, yet its timing and role in fundamental evolutionary processes remain controversial. While the formation of the isthmus was complete around 3 million years ago (Ma), recent studies have suggested prior intercontinental biotic exchange. In particular, the possibility of early intermittent land bridges facilitating colonization constitutes a potential mechanism for speciation and colonization before full closure of the isthmus. To test this hypothesis, we employed genomic methods to study the biogeography of the army ant genus Eciton, a group of keystone arthropod predators in Neotropical rainforests. Army ant colonies are unable to disperse across water and are therefore ideally suited to study the biogeographic impact of land bridge formation. Using a reduced representation genome sequencing approach, we show that all strictly Central American lineages of Eciton diverged from their respective South American sister lineage between 4 and 7 Ma, significantly prior to the complete closure of the isthmus. Furthermore, three of the lineage pairs form extensive and coincident secondary contact zones in Costa Rica and Nicaragua, with no evidence of gene flow. Such a discrete and repeated biogeographic pattern indicates at least two waves of army ant dispersal into Central America that were separated by significant genetic divergence times. Thus, by integrating phylogenomic, population genomic and geographic evidence, we show that early colonization of Central America across the emerging Isthmus of Panamá drove parallel speciation in Eciton army ants. © 2016 John Wiley & Sons Ltd.

  20. Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection.

    PubMed

    Liu, Jian; Bi, Shuping; Yang, Li; Gu, Xiaodong; Ma, Pengju; Gan, Ning; Wang, Xianlong; Long, Xiufeng; Zhang, Fuping

    2002-12-01

    The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of Al(III) in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of Al(III) for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for Al(III) speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll's method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.

  1. Partial island submergence and speciation in an adaptive radiation: a multilocus analysis of the Cuban green anoles.

    PubMed Central

    Glor, Richard E.; Gifford, Matthew E.; Larson, Allan; Losos, Jonathan B.; Schettino, Lourdes Rodríguez; Chamizo Lara, Ada R.; Jackman, Todd R.

    2004-01-01

    Sympatric speciation is often proposed to account for species-rich adaptive radiations within lakes or islands, where barriers to gene flow or dispersal may be lacking. However, allopatric speciation may also occur in such situations, especially when ranges are fragmented by fluctuating water levels. We test the hypothesis that Miocene fragmentation of Cuba into three palaeo-archipelagos accompanied species-level divergence in the adaptive radiation of West Indian Anolis lizards. Analysis of morphology, mitochondrial DNA (mt DNA) and nuclear DNA in the Cuban green anoles (carolinensis subgroup) strongly supports three pre dictions made by this hypothesis. First, three geographical sets of populations, whose ranges correspond with palaeo-archipelago boundaries, are distinct and warrant recognition as independent evolutionary lineages or species. Coalescence of nuclear sequence fragments sampled from these species and the large divergences observed between their mtDNA haplotypes suggest separation prior to the subsequent unification of Cuba ca. 5 Myr ago. Second, molecular phylogenetic relationships among these species reflect historical geographical relationships rather than morphological similarity. Third, all three species remain distinct despite extensive geographical contact subsequent to island unification, occasional hybridization and introgression of mtDNA haplotypes. Allopatric speciation initiated during partial island submergence may play an important role in speciation during the adaptive radiation of Anolis lizards. PMID:15539351

  2. A comparative analysis of island floras challenges taxonomy-based biogeographical models of speciation.

    PubMed

    Igea, Javier; Bogarín, Diego; Papadopulos, Alexander S T; Savolainen, Vincent

    2015-02-01

    Speciation on islands, and particularly the divergence of species in situ, has long been debated. Here, we present one of the first, complete assessments of the geographic modes of speciation for the flora of a small oceanic island. Cocos Island (Costa Rica) is pristine; it is located 550 km off the Pacific coast of Central America. It harbors 189 native plant species, 33 of which are endemic. Using phylogenetic data from insular and mainland congeneric species, we show that all of the endemic species are derived from independent colonization events rather than in situ speciation. This is in sharp contrast to the results of a study carried out in a comparable system, Lord Howe Island (Australia), where as much as 8.2% of the plant species were the product of sympatric speciation. Differences in physiography and age between the islands may be responsible for the contrasting patterns of speciation observed. Importantly, comparing phylogenetic assessments of the modes of speciation with taxonomy-based measures shows that widely used island biogeography approaches overestimate rates of in situ speciation.

  3. Molecular Dynamics Studies on the Effects of Water Speciation on Interfacial Structure and Dynamics in Silica-Filled PDMS Composites

    SciTech Connect

    Gee, R H; Maxwell, R S; Dinh, L N; Balazs, B

    2001-11-21

    Significant changes in materials properties of siloxane based polymers can be obtained by the addition of inorganic fillers. In silica-filled polydimethylsiloxane (PDMS) based composites the mechanism of this reinforcing behavior is presumably hydrogen bonding between surface hydroxyls and backbone siloxane species. We have chosen to investigate in detail the effect of chemisorbed and physisorbed water on the interfacial structure and dynamics in silica-filled PDMS based composites. Toward this end, we have combined molecular dynamics simulations and experimental studies employing DMA and Nh4R analysis. Our results suggest that the polymer-silica contact distance and the mobility of interfacial polymer chains significantly decreased as the hydration level at the interface was reduced. The reduced mobility of the PDMS chains in the interfacial domain reduced the overall, bulk, motional properties of the polymer, thus causing an effective ''stiffening'' of the polymer matrix. The role of the long-ranged Coulombic interactions on the structural features and chain dynamics of the polymer were also examined. Both are found to be strongly influenced by the electrostatic interactions as identified by the bond orientation time correlation function and local density distribution functions. These results have important implications for the design of nanocomposite silica-siloxane materials.

  4. Particle beam sample introduction into glow discharge plasmas for speciation analysis

    NASA Astrophysics Data System (ADS)

    Brewer, Tim M.; Castro, Joaudimir; Marcus, R. Kenneth

    2006-02-01

    This paper reviews the use of the particle beam (PB) as a transport-type interface for the introduction of liquid samples into glow discharge (GD) plasmas. Emphasis is placed on the PB interface as a coupling for liquid chromatography (LC) with optical emission spectroscopy (OES) and mass spectrometry (MS) detection methods. Advantages and disadvantages of the particle beam sample introduction for LC-MS and LC-OES as well as a comparison with other interfaces (i.e. moving belt) are covered. Fundamental aspects of the particle beam such as solvent removal and analyte delivery are highlighted. Furthermore, the development of the particle beam interface is discussed regarding its potential for providing "comprehensive speciation" analysis of solution-phase samples. Specifically, the particle beam/hollow cathode-optical emission spectroscopy (PB/HC-OES) technique provides information towards metal and non-metals determinations as well molecular species identification of organic compounds, organometallics, and small biomolecules via empirical formulae determinations. Particle beam-glow discharge mass spectrometry (PB/GDMS) also provides molecular species information through fragmentation pattern analysis of plasma-produced mass spectra that are similar in structure to electron impact (EI) sources. The evolving capabilities of the PB/GD couplings deliver analytical information that is not available from any other spectrochemical source. The technique has relevance to an incredible range of analytical applications and warrants further investigation by other researchers and instrument manufacturers.

  5. Arsenic speciation and fucoxanthin analysis from seaweed dietary supplements using LC-MS.

    PubMed

    Avula, Bharathi; Wang, Yan-Hong; Khan, Ikhlas A

    2015-01-01

    The study involves the analysis of total arsenic (As) in metallic form, and organic and inorganic As species from seaweeds and dietary supplements. The analysis provides data for dietary exposure estimates of inorganic species that are considered more toxic to humans than organic and total As. Total As was determined by acid digestion followed by inductively coupled plasma (ICP)-MS. To characterize the As species, solvent extraction with sonication and microwave extraction using various aqueous and aqueous/organic solvent mixtures were initially evaluated. The optimum As speciation method was determined to be water extraction followed by anion exchange HPLC coupled with ICP-MS. Optimization of chromatographic conditions led to baseline separation for six As species, including As acid, arsenous acid, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine, in approximately 8 min using gradient elution. Detection limits for all six compounds were in the range of 10-15 ng/mL. The data presented here will be valuable for the QA of analytical method development and surveys of total As and As species in dietary supplements. The most abundant As species found were arsenite [As(III)] and arsenate [As(V)]. The sum of inorganic As species present in the dietary supplements ranged from 1.2 to 31 μg/day. In addition, the dietary supplements purported to contain fucoxanthin, a carotenoid having pharmacological activities, were analyzed using ultra-performance LC-UV/MS.

  6. Models of speciation: where are we now?

    PubMed

    Gavrilets, Sergey

    2014-01-01

    Theory building is an integral part of biological research, in general, and of speciation research, in particular. Here, I review the modeling work on speciation done in the last 10 years or so, assessing the progress made and identifying areas where additional effort is required. Specific topics considered include evolutionary dynamics of genetic incompatibilities, spatial and temporal patterns of speciation, links to neutral theory of biodiversity, effects of multidimensionality of phenotype, sympatric and parapatric speciation, adaptive radiation, speciation by sexual conflict, and models tailored for specific biological systems. Particularly challenging questions for future theoretical research identified here are 1) incorporating gene regulatory networks in models describing accumulation of genetic incompatibilities; 2) integrating models of community ecology with those developed in speciation theory; 3) building models providing better insights on the dynamics of parapatric speciation; 4) modeling speciation in multidimensional ecological niches with mating preferences based on multidimensional mating cues and sexual characters; 5) linking microevolutionary processes with macroevolutionary patterns as observed in adaptive radiations and paleontological record; 6) modeling speciation in specific systems studied by empirical biologists; and 7) modeling human origins. The insights from dynamic models of speciation should be useful in developing statistical tools that would enable empiricists to infer the history of past evolutionary divergence and speciation from genomic data.

  7. The Dynamics of Mercury Speciation and Transport at a Central California Coastal Lagoon

    NASA Astrophysics Data System (ADS)

    Ganguli, P. M.; Swarzenski, P. W.; Dimova, N. T.; Merckling, J.; Kehrlein, N. C.; Hohn, R. A.; Richardson, C. M.; Johnson, C. D.; Fisher, A. T.; Lamborg, C. H.; Flegal, A. R., Jr.

    2014-12-01

    We evaluated spatial and temporal trends in total mercury and monomethylmercury (MMHg) in groundwater, lagoon water, and nearshore seawater to assess the drivers of MMHg production in a coastal lagoon system. Many West Coast streams transition from estuarine to lagoon conditions in the dry season when a sand berm develops at the stream mouth, restricting surface water exchange with the ocean. Because lagoons accumulate nutrients from their upstream watershed they are susceptible to eutrophication, which can promote the growth of anaerobic bacteria. In nearshore settings, these bacteria are primarily responsible for producing MMHg, a bioaccumulative neurotoxin. We found that MMHg concentrations in lagoon water (1 - 5 pM) were higher than in groundwater (0.2 - 1 pM) and coastal seawater (0.1 - 0.6 pM). Groundwater depth profiles combined with subsurface resistivity images suggest MMHg in lagoon water was transported through the sand berm to adjacent seawater. MMHg in seawater and groundwater followed similar trends, providing additional evidence of groundwater-surface water interaction. MMHg in groundwater directly below the lagoon was consistently higher where dissolved oxygen and NO3- decreased, implying MMHg production by anaerobic bacteria. Over a ~7-hour period we observed a 0.6 pM decrease in groundwater MMHg (1 to 0.4 pM) that coincided with a decrease in water temperature (16.5 to 13 °C). We hypothesize that microbial activity, and consequently MMHg production, were enhanced in warmer water. Because coastal lagoons support intricate food webs and serve as nurseries for a variety of organisms, processes that influence mercury speciation and transport in these ecosystems may have a disproportionate impact on nearshore mercury biogeochemical cycling.

  8. Recent Advances in On-Line Methods Based on Extraction for Speciation Analysis of Chromium in Environmental Matrices.

    PubMed

    Trzonkowska, Laura; Leśniewska, Barbara; Godlewska-Żyłkiewicz, Beata

    2016-07-03

    The biological activity of Cr(III) and Cr(VI) species, their chemical behavior, and toxic effects are dissimilar. The speciation analysis of Cr(III) and Cr(VI) in environmental matrices is then of great importance and much research has been devoted to this area. This review presents recent developments in on-line speciation analysis of chromium in such samples. Flow systems have proved to be excellent tools for automation of sample pretreatment, separation/preconcentration of chromium species, and their detection by various instrumental techniques. Analytical strategies used in chromium speciation analysis discussed in this review are divided into categories based on selective extraction/separation of chromium species on solid sorbents and liquid-liquid extraction of chromium species. The most popular strategy is that based on solid-phase extraction. Therefore, this review shows the potential of novel materials designed and used for selective binding of chromium species. The progress in miniaturization of measurement systems is also presented.

  9. Observation and analysis of speciated atmospheric mercury in Shangri-La, Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Fu, X. W.; Lin, C.-J.; Wang, X.; Feng, X. B.

    2015-01-01

    This study reports the concentrations and potential sources of speciated atmospheric mercury at the Shangri-La Atmosphere Watch Regional Station (SAWRS), a pristine high-altitude site (3580 m a.s.l.) in Tibetan Plateau, China. Total gaseous mercury (TGM, defined as the sum of gaseous elemental mercury, GEM, and gaseous oxidized mercury, GOM), GOM and particulate-bound mercury (PBM) were monitored from November 2009 to November 2010 to investigate the characteristics and potential influence of the Indian summer monsoon (ISM) and the Westerlies on atmospheric transport of mercury. The mean concentrations (± standard deviation) of TGM, PBM and GOM were 2.55 ± 0.73 ng m-3, 38.82 ± 31.26 pg m-3 and 8.22 ± 7.90 pg m-3, respectively. A notable seasonal pattern of TGM concentrations was observed with higher concentrations at the beginning and the end of the ISM season. High TGM concentrations (> 2.5 ng m-3) were associated with the transport of dry air that carried regional anthropogenic emissions from both Chinese domestic and foreign (e.g., Myanmar, Bay of Bengal, and northern India) sources based on analysis of HYSPLIT4 back trajectories. Somewhat lower PBM and GOM levels during the ISM period were attributed to the enhanced wet scavenging. The high GOM and PBM were likely caused by local photo-chemical transformation under low RH and the domestic biofuel burning in cold seasons.

  10. Reversed Phase Column HPLC-ICP-MS Conditions for Arsenic Speciation Analysis of Rice Flour.

    PubMed

    Narukawa, Tomohiro; Matsumoto, Eri; Nishimura, Tsutomu; Hioki, Akiharu

    2015-01-01

    New measurement conditions for arsenic speciation analysis of rice flour were developed using HPLC-ICP-MS equipped with a reversed phase ODS column. Eight arsenic species, namely, arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA), arsenobetaine (AsB) and arsenocholine (AsC), were separated and determined under the proposed conditions. In particular, As(III) and MMAA and DMAA and AsB were completely separated using a newly proposed eluent containing ammonium dihydrogen phosphate. Importantly, the sensitivity changes, in particular those of As(V) and As(III) caused by coexisting elements and by complex matrix composition, which had been problematical in previously reported methods, were eliminated. The new eluent can be applied to C8, C18 and C30 ODS columns with the same effectiveness and with excellent repeatability. The proposed analytical method was successfully applied to extracts of rice flour certified reference materials.

  11. Advances of CE-ICP-MS in speciation analysis related to metalloproteomics of anticancer drugs.

    PubMed

    Timerbaev, Andrei R; Pawlak, Katarzyna; Aleksenko, Svetlana S; Foteeva, Lidia S; Matczuk, Magdalena; Jarosz, Maciej

    2012-12-15

    The mode of action of metal-based anticancer drugs, including their accumulation in blood, transport, delivery to cancer cell, and cell processing (together with release of an active form and possibly targeting) is largely dependent on protein binding. Among analytical methods capable of providing a better understanding of metallodrug-protein interactions, capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS) detection is arguably a premier technique. Since its advent to the area of metallodrug proteomics in 2004, the benefits of CE-ICP-MS became evident, stimulating further research and methodological developments. This hyphenated technique's merits comprise an ability to separate rapidly and efficiently the parent drug and protein-bound drug form(s), with no alteration of original speciation in the sample, to identify the metal-containing species due to specific ICP-MS response, to measure the binding parameters (e.g. rate and equilibrium constants), and finally to quantify the metal-protein adducts in real-world samples. This review is aimed on offering the reader a summary of applications of CE-ICP-MS to various metallodrug-protein systems, with a focus on experimental strategies in use for the assessment of binding reactivity and affinity, monitoring in vitro cellular transformations and serum binding profiles, and ex vivo metallodrug-proteomic analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Dynamics in Epistasis Analysis.

    PubMed

    Awdeh, Aseel; Phenix, Hilary; Kaern, Mads; Perkins, Theodore

    2017-01-16

    Finding regulatory relationships between genes, including the direction and nature of influence between them, is a fundamental challenge in the field of molecular genetics. One classical approach to this problem is epistasis analysis. Broadly speaking, epistasis analysis infers the regulatory relationships between a pair of genes in a genetic pathway by considering the patterns of change in an observable trait resulting from single and double deletion of genes. While classical epistasis analysis has yielded deep insights on numerous genetic pathways, it is not without limitations. Here, we explore the possibility of dynamic epistasis analysis, in which, in addition to performing genetic perturbations of a pathway, we drive the pathway by a time-varying upstream signal. We explore the theoretical power of dynamical epistasis analysis by conducting an identifiability analysis of Boolean models of genetic pathways, comparing static and dynamic approaches. We find that even relatively simple input dynamics greatly increases the power of epistasis analysis to discriminate alternative network structures. Further, we explore the question of experiment design, and show that a subset of short time-varying signals, which we call dynamic primitives, allow maximum discriminative power with a reduced number of experiments.

  13. Molecular speciation and dynamics of oxidized triacylglycerols in lipid droplets: Mass spectrometry and coarse-grained simulations

    PubMed Central

    Mohammadyani, Dariush; Tyurin, Vladimir A.; O'Brien, Matthew; Sadovsky, Yoel; Gabrilovich, Dmitry I.; Klein-Seetharaman, Judith; Kagan, Valerian E.

    2014-01-01

    Lipid droplets (LDs) are ubiquitous and physiologically active organelles regulating storage and mobilization of lipids in response to metabolic demands. Among the constituent LD neutral lipids, such as triacylglycerols, cholesterol esters, and free fatty acids, oxidizable polyunsaturated molecular species may be quite abundant, yet the structural and functional roles of their oxidation products have not been studied. Our previous work documented the presence of these peroxidized species in LDs. Assuming that hydrophilic oxygen-containing functionalities may markedly change the hydrophobic/hydrophilic molecular balance, here we utilized computational modeling to test the hypothesis that lipid peroxidation causes redistribution of lipids between the highly hydrophobic core and the polar surface (phospho) lipid monolayer–the area enriched with integrated enzymatic machinery. Using quantitative liquid chromatography/mass spectrometry, we characterized molecular speciation of oxTAGs in LDs of dendritic cells in cancer and hypoxic trophoblasts cells as two cellular models associated with dyslipidemia. Among the many types of oxidized lipids identified, we found that oxidatively truncated forms and hydroxyl derivatives of TAGs were the prevailing oxidized lipid species in LDs in both cell types. Using coarse grained molecular dynamics (CG-MD) simulations we established that lipid oxidation changed their partitioning whereby oxidized lipids migrated into the outer monolayer of the LD, where they can affect essential metabolic pathways and undergo conversions, possibly leading to the formation of oxygenated lipid mediators. PMID:25110833

  14. Molecular speciation and dynamics of oxidized triacylglycerols in lipid droplets: Mass spectrometry and coarse-grained simulations.

    PubMed

    Mohammadyani, Dariush; Tyurin, Vladimir A; O'Brien, Matthew; Sadovsky, Yoel; Gabrilovich, Dmitry I; Klein-Seetharaman, Judith; Kagan, Valerian E

    2014-11-01

    Lipid droplets (LDs) are ubiquitous and physiologically active organelles regulating storage and mobilization of lipids in response to metabolic demands. Among the constituent LD neutral lipids, such as triacylglycerols, cholesterol esters, and free fatty acids, oxidizable polyunsaturated molecular species may be quite abundant, yet the structural and functional roles of their oxidation products have not been studied. Our previous work documented the presence of these peroxidized species in LDs. Assuming that hydrophilic oxygen-containing functionalities may markedly change the hydrophobic/hydrophilic molecular balance, here we utilized computational modeling to test the hypothesis that lipid peroxidation causes redistribution of lipids between the highly hydrophobic core and the polar surface (phospho)lipid monolayer-the area enriched with integrated enzymatic machinery. Using quantitative liquid chromatography/mass spectrometry, we characterized molecular speciation of oxTAGs in LDs of dendritic cells in cancer and hypoxic trophoblasts cells as two cellular models associated with dyslipidemia. Among the many types of oxidized lipids identified, we found that oxidatively truncated forms and hydroxyl derivatives of TAGs were the prevailing oxidized lipid species in LDs in both cell types. Using coarse-grained molecular dynamics (CG-MD) simulations we established that lipid oxidation changed their partitioning whereby oxidized lipids migrated into the outer monolayer of the LD, where they can affect essential metabolic pathways and undergo conversions, possibly leading to the formation of oxygenated lipid mediators. Published by Elsevier Inc.

  15. An improved leaping detector for flow analysis applied to iron speciation in drugs

    PubMed Central

    Santos, Sérgio R. B.; Araújo, Mário C. U.; Honorato, Ricardo S.; Zagatto, Elias A. G.; Lima, José F. C.; Lapa, Rui A. S.

    2000-01-01

    A low inner volume (ca. 64 ml) probe was built up in an injector-commutator in order to behave as a photometric leaping detector in flow analysis. It comprises a bicolour light-emitting diode (BLED), as a source of pulsed radiation in the red and green visible region, and two phototransistors as transducers. Sample injection, detector relocation, analytical signal recording, data treatment and definition of the spectral working range were computer-controlled. The feasibility of the system was initially demonstrated in the flow-injection speciation of iron, and the overall standard deviation of results was estimated as ± 1.6 and ± 1.4% for 1.6–4.0 mg l−1 Fe(II) or total iron after eightfold processing of synthetic samples. The system was further applied to drug analysis: the mean deviations of results for typical samples were estimated as ± 5.2 and ± 3.3%, and the relative standard deviation as ± 1.6 and ± 1.3% for Fe(II) and total iron, respectively. Results were compared with those obtained by a conventional spectrophotometric procedure and no statistic differences at the 95% confidence level were found. In relation to an earlier system with multi-site detection, the proposed system is more stable, presenting low drift with a relative standard deviation of 0.026% and 0.039% for measurements (n=120 during 4 h of observation) with green and red emission. It is also faster with a sampling rate of 133 h−1 and carryover problems are not found. The possibility of compensating the Schlieren noise by dual-wavelength spectrophotometry is discussed. PMID:18924860

  16. Meat speciation by restriction fragment length polymorphism analysis using an α-actin cDNA probe.

    PubMed

    Fairbrother, K S; Hopwood, A J; Lockley, A K; Bardsley, R G

    1998-09-01

    Classical DNA fingerprinting is based on separation of DNA restriction fragments by electrophoresis and hybridisation to nucleic acid probes containing repetitive nucleotide sequences. The use of such mini- or micro-satellite probes tends to yield patterns specific to an individual rather than to a species, hence their value in forensic analysis but general unsuitability for meat speciation. In the present study, a cDNA probe based on conserved sequences contained in members of the actin multigene family has been evaluated for potential application in meat speciation. Genomic DNA was extracted from muscle and digested with BamHI before electrophoresis and hybridisation to a murine α-actin cDNA probe. Beef, pork, lamb, horse, chicken and fish DNA restriction fragments formed characteristic 'fingerprints' which were reproducible and varied sufficiently to allow discrimination even between closely-related species. However no major differences were seen between individuals of the same breed or between different breeds within a species. When DNA obtained from fresh tissue and also from meat heated at 120 °C was analysed, the gel patterns were essentially the same. An attractive feature of this approach is that it employs a single cross-reacting probe and set of conditions, and gives different patterns with all species so far studied. This simplicity suggests applications in meat speciation or related areas of biology.

  17. Cesium Speciation in Dust from Municipal Solid Waste and Sewage Sludge Incineration by Synchrotron Radiation Micro-X-ray Analysis.

    PubMed

    Shiota, Kenji; Takaoka, Masaki; Fujimori, Takashi; Oshita, Kazuyuki; Terada, Yasuko

    2015-11-17

    The chemical behavior of Cs in waste incineration processes is important to consider when disposing of radionuclide-contaminated waste from the Fukushima Daiichi nuclear power plant accident in Japan. To determine the speciation of Cs, we attempted the direct speciation of trace amounts of stable Cs in the dust from municipal solid waste incineration (MSWI) and sewage sludge incineration (SSI) by micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption fine structure (μ-XAFS) at the SPring-8 facility. The μ-XRF results revealed that locally produced Cs was present in MSWI and SSI dust within the cluster size range of 2-10 μm. The μ-XAFS analysis confirmed that the speciation of Cs in MSWI dust was similar to that of CsCl, while in SSI dusts it was similar to pollucite. The solubility of Cs was considered to be influenced by the exact Cs species present in incineration residue.

  18. Initial Analysis of VOCs Speciation in CREATE Emissions Inventory using the MAPS-Seoul Aircraft Field Campaign

    NASA Astrophysics Data System (ADS)

    Bu, C.; Woo, J. H.; Lee, Y.; Kim, J.; Choi, K. C.; Kim, Y.; Kim, J.; Jang, Y. K.; Kim, S.

    2016-12-01

    As the first international cooperative air quality field study, the MAPS-Seoul (Megacity Air Pollution Studies-Seoul) aircraft mission was conducted in May - June 2016 over the South Korea, to understand of climate and atmospheric environment. The aircraft carried observation instruments for measurements of GHGs, ozone and its precursors, aerosols, and chemical tracers. The CREATE (Comprehensive Regional Emissions inventory for Atmospheric Environment) emissions inventory and SMOKE-Asia emission processing system were used to support chemical forecasting and to serve as a priori for evaluation. Initial results of comparison studies show large discrepancies in VOC species over the South Korea - especially over urban regions. Several VOC species observed high near megacities and petro-chemical plants but under-predicted by chemical transport models (CTMs) - possibly due to relatively low emissions. The chemical speciation profiles and emissions inventory for each emission sources, therefore, have to be re-visited to improve emissions information. In this study, we have; 1) re-examined our emissions inventory and emission speciation processes, 2) and tried to find possible missing sources and alternative chemical speciation profiles, to improve our modelling emissions inventory. Initial review of the mapping and classification profiles, the original US chemical speciation profiles were found to be low in partitioning painting and surface coating sources, although they are the very significant contributors. Unlike other major national cities in China, Shanghai's VOC emissions fraction seems very similar to that of Seoul. Continuous analysis of major urban and industrial areas of the country will be presented at site.Acknowledgements : This subject is supported by Korea Ministry of Environment as "Climate Change Correspondence Program". This work was supported by a grant from the National Institute of Environment Research (NIER), funded by the Ministry of Environment

  19. Special Speciation

    ERIC Educational Resources Information Center

    Countryman, Lyn L.; Maroo, Jill D.

    2015-01-01

    Considerable anecdotal evidence indicates that some of the most difficult concepts that both high school and undergraduate elementary-education students struggle with are those surrounding evolutionary principles, especially speciation. It's no wonder that entry-level biology students are confused, when biologists have multiple definitions of…

  20. Special Speciation

    ERIC Educational Resources Information Center

    Countryman, Lyn L.; Maroo, Jill D.

    2015-01-01

    Considerable anecdotal evidence indicates that some of the most difficult concepts that both high school and undergraduate elementary-education students struggle with are those surrounding evolutionary principles, especially speciation. It's no wonder that entry-level biology students are confused, when biologists have multiple definitions of…

  1. Flight Dynamics Analysis Branch

    NASA Technical Reports Server (NTRS)

    Stengle, Tom; Flores-Amaya, Felipe

    2000-01-01

    This report summarizes the major activities and accomplishments carried out by the Flight Dynamics Analysis Branch (FDAB), Code 572, in support of flight projects and technology development initiatives in fiscal year 2000. The report is intended to serve as a summary of the type of support carried out by the FDAB, as well as a concise reference of key accomplishments and mission experience derived from the various mission support roles. The primary focus of the FDAB is to provide expertise in the disciplines of flight dynamics, spacecraft trajectory, attitude analysis, and attitude determination and control. The FDAB currently provides support for missions and technology development projects involving NASA, government, university, and private industry.

  2. Monitoring the production process of selenized yeast by elemental speciation analysis.

    PubMed

    Rampler, Evelyn; Rose, Stephan; Wieder, Dominik; Ganner, Anja; Dohnal, Ilse; Dalik, Thomas; Hann, Stephan; Koellensperger, Gunda

    2012-11-01

    Elemental speciation analysis was implemented as an essential tool set addressing optimum fermentation conditions for the production of selenized yeast feed supplements. Accordingly, the study addressed intracellular levels of (1) total selenium and sulfur, (2) seleno methionine (SeMet), (3) cysteine (Cys) and methionine (Met) and (4) selenite and selenate. Dedicated sample preparation- and LC-ICP-MS methods were implemented and validated using the reference material Selm-1. Excellent repeatability precisions <10% (n = 4 biological replicates) could be obtained for all parameters. The study comprised fermentation monitoring over 72 hours (6 different time points) for a Saccharomyces cerevisiae strain under different selenite feed conditions. It was observed that for this strain an increase in the selenium concentration in the fermentation feed by 50% did not result in enhanced selenium accumulation. Fermentation monitoring of three different Saccharomyces cerevisiae strains under the same conditions showed strain specific selenium uptake after 72 hours. The strain with the lowest cell viability of 60% showed the lowest SeMet content. After 47 h of fermentation, all strains reached a critical point, at which seleno methionine accounted for approximately 100% of the total selenium and cell viability started to decrease. This could be explained by sulfur limitation and/or excess of the seleno methionine storage capacity. Strains showing cell viability of approx. 90% after 72 hours of fermentation revealed SeMet concentrations up to 3000 μg g(-1). In the final product, an apparent threshold level for Met/SeMet of approx. 1 was observed for all strains.

  3. Extraction tool and matrix effects on arsenic speciation analysis in cell lines.

    PubMed

    Yehiayan, Lucy; Membreno, Nellymar; Matulis, Shannon; Boise, Lawrence H; Cai, Yong

    2011-08-12

    Arsenic glutathione (As-GSH) complexes have been suggested as possible metabolites in arsenic (As) metabolism. Extensive research has been performed on the toxicological and apoptotic effects of As, while few reports exist on its metabolism at the cellular level due to the analytical challenges. In this study, an efficient extraction method for arsenicals from cell lines was developed. Evaluation of extraction tools; vortex, ultrasonic bath and ultrasonic probe and solvents; water, chemicals (methanol and trifluoroacetic acid), and enzymes (pepsin, trypsin and protease) was performed. GSH effect on the stability of As-GSH complexes was studied. Arsenic metabolites in dimethylarsino glutathione (DMA(GS)) incubated multiple myeloma cell lines were identified following extraction. Intracellular GSH concentrations of myeloma cell lines were imitated in the extraction media and its corresponding effect on the stability and distribution of As metabolites was studied. An enhancement in both extraction recoveries and time efficiency with the use of the ultrasonic probe was observed. Higher stabilities for the As species in water, pepsin and trypsin were obtained. The presence of 0.5mM GSH in the extraction media (PBS, pH 7.4) could not stabilize the As-GSH complexes compared to the 5mM GSH, where high stabilization of the complexes was observed over a 5 day storage study. Finally, the speciation analysis of the DMA(GS) culture incubated cell lines in the presence or absence of GSH revealed the important role GSH plays in the preservation of DMA(GS) identity. Hence, caution is required during the extraction of arsenicals especially the As-GSH complexes, since their identification is highly dependent on GSH concentration. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Extraction tool and matrix effects on arsenic speciation analysis in cell lines

    PubMed Central

    Yehiayan, Lucy; Membreno, Nellymar; Matulis, Shannon; Boise, Lawrence H.; Cai, Yong

    2011-01-01

    Arsenic glutathione (As-GSH) complexes have been suggested as possible metabolites in arsenic (As) metabolism. Extensive research has been performed on the toxicological and apoptotic effects of As, while few reports exist on its metabolism at the cellular level due to the analytical challenges. In this study, an efficient extraction method for arsenicals from cell lines was developed. Evaluation of extraction tools; vortex, ultrasonic bath and ultrasonic probe and solvents; water, chemicals (methanol and trifluoroacetic acid), and enzymes (pepsin, trypsin and protease) was performed. GSH effect on the stability of As-GSH complexes was studied. Arsenic metabolites in dimethylarsino glutathione (DMA(GS)) incubated multiple myeloma cell lines were identified following extraction. Intracellular GSH concentrations of myeloma cell lines were imitated in the extraction media and its corresponding effect on the stability and distribution of As metabolites was studied. An enhancement in both extraction recoveries and time efficiency with the use of the ultrasonic probe was observed. Higher stabilities for the As species in water, pepsin and trypsin were obtained. The presence of 0.5 mM GSH in the extraction media (PBS, pH = 7.4) could not stabilize the As-GSH complexes compared to the 5 mM GSH, where high stabilization of the complexes was observed over a 5 day storage study. Finally, the speciation analysis of the DMA(GS) culture incubated cell lines in the presence or absence of GSH revealed the important role GSH plays in the preservation of DMA(GS) identity. Hence, caution is required during the extraction of arsenicals especially the As-GSH complexes, since their identification is highly dependent on GSH concentration. PMID:21704773

  5. Flow-injection analysis with multidetection as a useful technique for metal speciation.

    PubMed

    Ruz, J; Rios, A; de Castro, M D; Valcarcel, M

    1986-03-01

    The analytical potential of a closed flow-injection system with multidetection by a single detector (for calculation of rate constants, reaction rate, dilution and amplification methods, etc.) is extended to simultaneous determinations for chromium speciation, with injection of the reagent(s) into the sample solution (which acts as the carrier).

  6. Phosphorus sources, speciation and dynamics in the lowland eutrophic River Kennet, UK.

    PubMed

    Jarvi, Helen P; Neal, Colin; Williams, Richard J; Neal, Margaret; Wickham, Heather D; Hill, Linda K; Wade, Andrew J; Warwick, Alan; White, John

    2002-01-23

    This paper examines the behaviour of phosphorus (P) in a lowland chalk (Cretaceous-age) stream, the upper River Kennet in southern England, which has been subject to P remediation by tertiary treatment at the major sewage treatment works in the area. The effects of treatment are examined in relation to boron, a conservative tracer of sewage effluent and in terms of the relative contributions of soluble reactive phosphorus (SRP) loads from point and diffuse sources, and in-stream SRP loads. These results indicate a baseline reduction in in-stream SRP concentrations immediately following P-treatment of approximately 72%. Subsequent high flows result in a greater contribution of diffuse inputs and increases in SRP levels relative to the initial post-treatment period. The dynamics of SRP and particulate phosphorus (PP) are examined under a wide range of river flow conditions. Given the flashy nature of near-surface runoff in the River Kennet, sub-weekly (daily automated) sampling was used to examine the dynamics in SRP and PP concentrations in response to storm events. Simple empirical models linking weekly SRP concentrations with flow were developed. The empirical models were successfully applied to the daily data, to partition TP measurements and provide an estimate of daily SRP and PP concentrations. Mass balance studies were used to examine net gains and losses along the experimental river reach and indicate large net losses (up to 60%) during the extreme low flows and high SRP concentrations prior to P-treatment, which may be linked to extensive epiphytic growth. Phosphorus dynamics and response to P-treatment are discussed in relation to hydrological controls in permeable chalk catchments and wider implications for eutrophication management are examined.

  7. Drop Dynamics and Speciation in Isolation of Metals from Liquid Wastes by Reactive Scavenging

    SciTech Connect

    Arne J. Pearlstein; Alexander Scheeline

    2002-08-30

    Computational and experimental studies of the motion and dynamics of liquid drops in gas flows were conducted with relevance to reactive scavenging of metals from atomized liquid waste. Navier-Stoke's computations of deformable drops revealed a range of conditions from which prolate drops are expected, and showed how frajectiones of deformable drops undergoing deceleration can be computed. Experimental work focused on development of emission fluorescence, and scattering diagnostics. The instrument developed was used to image drop shapes, soot, and nonaxisymmetric departures from steady flow in a 22kw combustor

  8. Structural dynamics analysis

    NASA Astrophysics Data System (ADS)

    Housner, J. M.; Anderson, M.; Belvin, W.; Horner, G.

    1985-04-01

    Dynamic analysis of large space antenna systems must treat the deployment as well as vibration and control of the deployed antenna. Candidate computer programs for deployment dynamics, and issues and needs for future program developments are reviewed. Some results for mast and hoop deployment are also presented. Modeling of complex antenna geometry with conventional finite element methods and with repetitive exact elements is considered. Analytical comparisons with experimental results for a 15 meter hoop/column antenna revealed the importance of accurate structural properties including nonlinear joints. Slackening of cables in this antenna is also a consideration. The technology of designing actively damped structures through analytical optimization is discussed and results are presented.

  9. Structural dynamics analysis

    NASA Technical Reports Server (NTRS)

    Housner, J. M.; Anderson, M.; Belvin, W.; Horner, G.

    1985-01-01

    Dynamic analysis of large space antenna systems must treat the deployment as well as vibration and control of the deployed antenna. Candidate computer programs for deployment dynamics, and issues and needs for future program developments are reviewed. Some results for mast and hoop deployment are also presented. Modeling of complex antenna geometry with conventional finite element methods and with repetitive exact elements is considered. Analytical comparisons with experimental results for a 15 meter hoop/column antenna revealed the importance of accurate structural properties including nonlinear joints. Slackening of cables in this antenna is also a consideration. The technology of designing actively damped structures through analytical optimization is discussed and results are presented.

  10. Evolutionary dynamics at high latitudes: speciation and extinction in polar marine faunas.

    PubMed

    Clarke, Andrew; Crame, J Alistair

    2010-11-27

    Ecologists have long been fascinated by the flora and fauna of extreme environments. Physiological studies have revealed the extent to which lifestyle is constrained by low temperature but there is as yet no consensus on why the diversity of polar assemblages is so much lower than many tropical assemblages. The evolution of marine faunas at high latitudes has been influenced strongly by oceanic cooling during the Cenozoic and the associated onset of continental glaciations. Glaciation eradicated many shallow-water habitats, especially in the Southern Hemisphere, and the cooling has led to widespread extinction in some groups. While environmental conditions at glacial maxima would have been very different from those existing today, fossil evidence indicates that some lineages extend back well into the Cenozoic. Oscillations of the ice-sheet on Milankovitch frequencies will have periodically eradicated and exposed continental shelf habitat, and a full understanding of evolutionary dynamics at high latitude requires better knowledge of the links between the faunas of the shelf, slope and deep-sea. Molecular techniques to produce phylogenies, coupled with further palaeontological work to root these phylogenies in time, will be essential to further progress.

  11. Evolutionary dynamics at high latitudes: speciation and extinction in polar marine faunas

    PubMed Central

    Clarke, Andrew; Crame, J. Alistair

    2010-01-01

    Ecologists have long been fascinated by the flora and fauna of extreme environments. Physiological studies have revealed the extent to which lifestyle is constrained by low temperature but there is as yet no consensus on why the diversity of polar assemblages is so much lower than many tropical assemblages. The evolution of marine faunas at high latitudes has been influenced strongly by oceanic cooling during the Cenozoic and the associated onset of continental glaciations. Glaciation eradicated many shallow-water habitats, especially in the Southern Hemisphere, and the cooling has led to widespread extinction in some groups. While environmental conditions at glacial maxima would have been very different from those existing today, fossil evidence indicates that some lineages extend back well into the Cenozoic. Oscillations of the ice-sheet on Milankovitch frequencies will have periodically eradicated and exposed continental shelf habitat, and a full understanding of evolutionary dynamics at high latitude requires better knowledge of the links between the faunas of the shelf, slope and deep-sea. Molecular techniques to produce phylogenies, coupled with further palaeontological work to root these phylogenies in time, will be essential to further progress. PMID:20980314

  12. Dynamic Contingency Analysis Tool

    SciTech Connect

    2016-01-14

    The Dynamic Contingency Analysis Tool (DCAT) is an open-platform and publicly available methodology to help develop applications that aim to improve the capabilities of power system planning engineers to assess the impact and likelihood of extreme contingencies and potential cascading events across their systems and interconnections. Outputs from the DCAT will help find mitigation solutions to reduce the risk of cascading outages in technically sound and effective ways. The current prototype DCAT implementation has been developed as a Python code that accesses the simulation functions of the Siemens PSS/E planning tool (PSS/E). It has the following features: It uses a hybrid dynamic and steady-state approach to simulating the cascading outage sequences that includes fast dynamic and slower steady-state events. It integrates dynamic models with protection scheme models for generation, transmission, and load. It models special protection systems (SPSs)/remedial action schemes (RASs) and automatic and manual corrective actions. Overall, the DCAT attempts to bridge multiple gaps in cascading-outage analysis in a single, unique prototype tool capable of automatically simulating and analyzing cascading sequences in real systems using multiprocessor computers.While the DCAT has been implemented using PSS/E in Phase I of the study, other commercial software packages with similar capabilities can be used within the DCAT framework.

  13. Intraparticulate Metal Speciation Analysis of Soft Complexing Nanoparticles. The Intrinsic Chemical Heterogeneity of Metal-Humic Acid Complexes.

    PubMed

    Town, Raewyn M; van Leeuwen, Herman P

    2016-11-03

    The counterion condensation-Donnan (CCD) model for the electrostatic features of soft, charged nanoparticles (NPs) is applied to the determination of the intrinsic stability constants, K̅int, for inner-sphere Cd(II) and Cu(II) complexes with humic acid NPs. The novel CCD model accounts for the strong ion condensation potential for higher valency counterions within the intraparticulate double layer zone of the soft NP. The approach offers new insights into the intrinsic heterogeneity of the HA complexes, as revealed by the intraparticulate speciation as a function of the true degree of inner-sphere complexation, θM. The ensuing intrinsic heterogeneity parameters, Γ, for CdHA and CuHA complexes are in very good agreement with those obtained from dynamic electrochemical stripping chronopotentiometric measurements. The overall intraparticulate metal ion speciation is found to depend on θM: at low θM the strong inner-sphere complexes predominate whereas at higher θM values, electrically condensed M may be an equally significant or even larger fraction of the particle-associated M.

  14. Iron speciation in natural waters by sequential injection analysis with a hexadentate 3-hydroxy-4-pyridinone chelator as chromogenic agent.

    PubMed

    Miranda, Joana L A; Mesquita, Raquel B R; Nunes, Ana; Rangel, Maria; Rangel, António O S S

    2016-02-01

    A sequential injection method for iron speciation in various types of natural waters was developed using a synthesised hexadentate 3-hydroxy-4-pyridinone chelator (CP256). The denticity of the ligand that allow formation of the corresponding iron(III) complex in a 1:1 stoichiometry proved to be highly advantageous, in comparison with parent bidentate, hydroxy-4-piridinone chelators, with a two fold increase of reaction sensitivity and over 65% decrease of the LOD. A solid phase extraction approach was employed to attain matrix elimination, facilitating iron(III) determination and application to high salinity waters. The combination with the total iron determination obtained by the direct reaction of the ligand resulted in iron speciation. Two detection spectrophotometric cells were tested, a conventional flow cell (CFC) and a liquid waveguide capillary cell (LWCC). The dynamic concentration ranges were 0.1-2 mg/L with the CFC detection and 0.005-0.1 mg/L with the LWCC, with limit of detection of 30 µg/L and 6 µg/L, respectively. The developed method was successfully applied to a variety of natural waters. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Localization and speciation of arsenic in Glomus intraradices by synchrotron radiation spectroscopic analysis.

    PubMed

    González-Chávez, Ma del Carmen A; Miller, Bradley; Maldonado-Mendoza, Ignacio Eduardo; Scheckel, Kirk; Carrillo-González, Rogelio

    2014-01-01

    The protective mechanisms employed by arbuscular mycorrhizal fungi (AMF) to reduce the toxic effects of arsenic on host plants remain partially unknown. The goal of this research was identifying the in situ localization and speciation of arsenic (As) in the AM fungus Rhizophagus intraradices [formerly named Glomus intraradices] exposed to arsenate [As(V)]. By using a two-compartment in vitro fungal cultures of R. intraradices-transformed carrot roots, microspectroscopic X-ray fluorescence (μ-XRF), and microspectroscopic X-ray absorption near edge structure (μ-XANES), we observed that As(V) is absorbed after 1 h in the hyphae of AMF. Three hours after exposure a decrease in the concentration of As was noticed and after 24 and 72 h no detectable As concentrations were perceived suggesting that As taken up was pumped out from the hyphae. No As was detected within the roots or hyphae in the root compartment zone three or 45 h after exposure. This suggests a dual protective mechanism to the plant by rapidly excluding As from the fungus and preventing As translocation to the plant root. μ-XANES data showed that gradual As(V) reduction occurred in the AM hyphae between 1 and 3 h after arsenic exposure and was completed after 6 h. Principal component analysis (PCA) and linear combination fitting (LCF) of μ-XANES data showed that the dominant species after reduction of As(V) by R. intraradices extra-radical hyphal was As(III) complexed with a reduced iron(II) carbonate compound. The second most abundant As species present was As(V)-iron hydroxides. The remaining As(III) compounds identified by the LCF analyses suggested these molecules were made of reduced As and S. These results increase our knowledge on the mechanism of As transport in AMF and validate our hypotheses that R. intraradices directly participates in arsenic detoxification. These fungal mechanisms may help AMF colonized plants to increase their tolerance to As at contaminated sites.

  16. Motorcycle dynamics by multibody dynamics analysis

    SciTech Connect

    Imaizumi, Hirohide; Fujioka, Takehiko

    1995-12-31

    The purpose of this paper is to construct simulation models of a motorcycle with a rider by use of multibody dynamics analysis (MDA). Three types of MDA models are developed for evaluation of the effectiveness of MDA for motorcycle dynamics. Impulse responses with parameter study and lane change maneuvers are calculated. The results of simulations agree with that of experiments well and effectiveness of MDA to the motorcycle dynamics field is shown.

  17. Atmospheric mercury speciation dynamics at the high-altitude Pic du Midi Observatory, southern France

    NASA Astrophysics Data System (ADS)

    Fu, Xuewu; Marusczak, Nicolas; Heimbürger, Lars-Eric; Sauvage, Bastien; Gheusi, François; Prestbo, Eric M.; Sonke, Jeroen E.

    2016-05-01

    Continuous measurements of atmospheric gaseous elemental mercury (GEM), particulate bound mercury (PBM) and gaseous oxidized mercury (GOM) at the high-altitude Pic du Midi Observatory (PDM Observatory, 2877 m a.s.l.) in southern France were made from November 2011 to November 2012. The mean GEM, PBM and GOM concentrations were 1.86 ng m-3, 14 pg m-3 and 27 pg m-3, respectively and we observed 44 high PBM (peak PBM values of 33-98 pg m-3) and 61 high GOM (peak GOM values of 91-295 pg m-3) events. The high PBM events occurred mainly in cold seasons (winter and spring) whereas high GOM events were mainly observed in the warm seasons (summer and autumn). In cold seasons the maximum air mass residence times (ARTs) associated with high PBM events were observed in the upper troposphere over North America. The ratios of high PBM ARTs to total ARTs over North America, Europe, the Arctic region and Atlantic Ocean were all elevated in the cold season compared to the warm season, indicating that the middle and upper free troposphere of the Northern Hemisphere may be more enriched in PBM in cold seasons. PBM concentrations and PBM / GOM ratios during the high PBM events were significantly anti-correlated with atmospheric aerosol concentrations, air temperature and solar radiation, suggesting in situ formation of PBM in the middle and upper troposphere. We identified two distinct types of high GOM events with the GOM concentrations positively and negatively correlated with atmospheric ozone concentrations, respectively. High GOM events positively correlated with ozone were mainly related to air masses from the upper troposphere over the Arctic region and middle troposphere over the temperate North Atlantic Ocean, whereas high GOM events anti-correlated with ozone were mainly related to air masses from the lower free troposphere over the subtropical North Atlantic Ocean. The ARTs analysis demonstrates that the lower and middle free troposphere over the North Atlantic Ocean was

  18. Speciation in fungal and oomycete plant pathogens.

    PubMed

    Restrepo, Silvia; Tabima, Javier F; Mideros, Maria F; Grünwald, Niklaus J; Matute, Daniel R

    2014-01-01

    The process of speciation, by definition, involves evolution of one or more reproductive isolating mechanisms that split a single species into two that can no longer interbreed. Determination of which processes are responsible for speciation is important yet challenging. Several studies have proposed that speciation in pathogens is heavily influenced by host-pathogen dynamics and that traits that mediate such interactions (e.g., host mobility, reproductive mode of the pathogen, complexity of the life cycle, and host specificity) must lead to reproductive isolation and ultimately affect speciation rates. In this review, we summarize the main evolutionary processes that lead to speciation of fungal and oomycete plant pathogens and provide an outline of how speciation can be studied rigorously, including novel genetic/genomic developments.

  19. Confinement Vessel Dynamic Analysis

    SciTech Connect

    R. Robert Stevens; Stephen P. Rojas

    1999-08-01

    A series of hydrodynamic and structural analyses of a spherical confinement vessel has been performed. The analyses used a hydrodynamic code to estimate the dynamic blast pressures at the vessel's internal surfaces caused by the detonation of a mass of high explosive, then used those blast pressures as applied loads in an explicit finite element model to simulate the vessel's structural response. Numerous load cases were considered. Particular attention was paid to the bolted port connections and the O-ring pressure seals. The analysis methods and results are discussed, and comparisons to experimental results are made.

  20. Preconcentration and Speciation of Trace Elements and Trace-Element Analogues of Radionuclides by Neutron Activation Analysis

    SciTech Connect

    Chatt, A.

    1999-11-14

    We have developed a number of preconcentration neutron activation analysis (PNAA) methods in our laboratory for the determination of trace elements in a variety of complex sample matrices. We developed a number of cocrystallization and coprecipitation methods for the determination of trace elements in water samples. We developed several methods for the determination of I in foods and diets. We have developed a number of PNAA methods in our laboratory We determined As and Sb in geological materials and natural waters by coprecipitation with Se and Au in silicate rocks and ores by coprecipitation with Te followed by NAA. We developed an indirect NAA method for the determination of B in leachates of borosilicate glass. We have been interested in studying the speciation of Am, Tc, and Np in simulated vitrified groundwater leachates of high-level wastes under oxid and anoxic conditions using a number of techniques. We then used PNAA methods to study speciation of trace-element analogues of radionuclides. We have been able to apply biochemical techniques and NAA for the separation, preconcentration, and characterization of metalloprotein and protein-bound trace-element species in subcellular fractions of bovine kidneys. Lately, we have concentrated our efforts to develop chemical and biochemical methods in conjunction with NAA, NMR, and MS for the separation and identification of extractable organohalogens (EOX) in tissues of beluga whales, cod, and northern pink shrimp

  1. Diversification dynamics of rhynchostomatian ciliates: the impact of seven intrinsic traits on speciation and extinction in a microbial group.

    PubMed

    Vďačný, Peter; Rajter, Ľubomír; Shazib, Shahed Uddin Ahmed; Jang, Seok Won; Shin, Mann Kyoon

    2017-08-30

    Ciliates are a suitable microbial model to investigate trait-dependent diversification because of their comparatively complex morphology and high diversity. We examined the impact of seven intrinsic traits on speciation, extinction, and net-diversification of rhynchostomatians, a group of comparatively large, predatory ciliates with proboscis carrying a dorsal brush (sensoric structure) and toxicysts (organelles used to kill the prey). Bayesian estimates under the binary-state speciation and extinction model indicate that two types of extrusomes and two-rowed dorsal brush raise diversification through decreasing extinction. On the other hand, the higher number of contractile vacuoles and their dorsal location likely increase diversification via elevating speciation rate. Particular nuclear characteristics, however, do not significantly differ in their diversification rates and hence lineages with various macronuclear patterns and number of micronuclei have similar probabilities to generate new species. Likelihood-based quantitative state diversification analyses suggest that rhynchostomatians conform to Cope's rule in that their diversity linearly grows with increasing body length and relative length of the proboscis. Comparison with other litostomatean ciliates indicates that rhynchostomatians are not among the cladogenically most successful lineages and their survival over several hundred million years could be associated with their comparatively large and complex bodies that reduce the risk of extinction.

  2. Using FTIR-photoacoustic spectroscopy for phosphorus speciation analysis of biochars

    NASA Astrophysics Data System (ADS)

    Bekiaris, Georgios; Peltre, Clément; Jensen, Lars S.; Bruun, Sander

    2016-11-01

    In the last decade, numerous studies have evaluated the benefits of biochar for improving soil quality. The purposes of the current study were to use Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS) to analyse P species in biochar and to determine the effect of pyrolysis temperature on P speciation. The photoacoustic detector has a range of advantages for the very dark biochar samples in comparison to more traditional reflectance or transmission FTIR detectors. The spectra turned out to be more informative in the regions with P vibrations for biochar produced at temperatures above 400 °C, where most of the remaining organic compounds were aromatic and therefore not overlapping with the P vibrations. For biochars produced from the solid fraction of digestate from biogas production, an increase in the pyrolysis temperature led to the formation of a large variety of P species. Hydroxylapatite and tricalcium phosphate were the most dominant P species in the mid to high temperature range (600-900 °C), while at 1050 °C apatite, iron phosphates, variscite and calcium phosphates were identified. However, the changes in P speciation in biochars produced from bone meal at different temperatures were smaller than in the biochars from digestate. Hydroxylapatite and calcium phosphates were identified in biochar produced at all temperatures, while there was some indication of struvite formation.

  3. DIDA - Dynamic Image Disparity Analysis.

    DTIC Science & Technology

    1982-12-31

    Understanding, Dynamic Image Analysis , Disparity Analysis, Optical Flow, Real-Time Processing ___ 20. ABSTRACT (Continue on revere side If necessary aid identify...three aspects of dynamic image analysis must be studied: effectiveness, generality, and efficiency. In addition, efforts must be made to understand the...environment. A better understanding of the need for these Limiting constraints is required. Efficiency is obviously important if dynamic image analysis is

  4. Local dynamic mechanical analysis.

    PubMed

    Foschia, Raphael; Jobin, Marc; Hengsberger, Stefan

    2009-01-01

    While new materials with tailored properties appear every day, the need of appropriate characterization tools is still an important concern. Analyses of thin films on thick substrate are often highly influenced by the substrate properties. A dynamical nanoindentation system has been designed and built through the integration of a nanoindenter head equipped with capacitive displacement sensing, scanning probe microscope with related XYZ scanning electronics and an additional transducer for sample actuation. Our Local-Dynamic Mechanical Analysis (L-DMA) setup allows for both, tip and sample modulation mode what somehow contrasts with commercially available systems. This issue allows for direct comparison between both techniques and therefore for consistent quantitative mechanical measurements. The system offers two distinctive measurement techniques, local mechanical spectroscopy and mechanical imaging modes. Bulk materials as well as thin films of ceramics and polymers have been used for testing and validating the setup. The instrument has been modeled in sample modulation mode and experimental results obtained for different materials were compared with simulation data.

  5. Sample preparation for arsenic speciation analysis in baby food by generation of substituted arsines with atomic absorption spectrometry detection.

    PubMed

    Huber, Charles S; Vale, Maria Goreti R; Dessuy, Morgana B; Svoboda, Milan; Musil, Stanislav; Dědina, Jiři

    2017-12-01

    A slurry sampling procedure for arsenic speciation analysis in baby food by arsane generation, cryogenic trapping and detection with atomic absorption spectrometry is presented. Several procedures were tested for slurry preparation, including different reagents (HNO3, HCl and tetramethylammonium hydroxide - TMAH) and their concentrations, water bath heating and ultrasound-assisted agitation. The best results for inorganic arsenic (iAs) and dimethylarsinate (DMA) were reached when using 3molL(-1) HCl under heating and ultrasound-assisted agitation. The developed method was applied for the analysis of five porridge powder and six baby meal samples. The trueness of the method was checked with a certified reference material (CRM) of total arsenic (tAs), iAs and DMA in rice (ERM-BC211). Arsenic recoveries (mass balance) for all samples and CRM were performed by the determination of the tAs by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted digestion and its comparison against the sum of the results from the speciation analysis. The relative limits of detection were 0.44, 0.24 and 0.16µgkg(-1) for iAs, methylarsonate and DMA, respectively. The concentrations of the most toxic arsenic species (iAs) in the analyzed baby food samples ranged between 4.2 and 99µgkg(-1) which were below the limits of 300, 200 and 100µgkg(-1) set by the Brazilian, Chinese and European legislation, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Field and laboratory arsenic speciation methods and their application to natural-water analysis

    USGS Publications Warehouse

    Bednar, A.J.; Garbarino, J.R.; Burkhardt, M.R.; Ranville, J.F.; Wildeman, T.R.

    2004-01-01

    The toxic and carcinogenic properties of inorganic and organic arsenic species make their determination in natural water vitally important. Determination of individual inorganic and organic arsenic species is critical because the toxicology, mobility, and adsorptivity vary substantially. Several methods for the speciation of arsenic in groundwater, surface-water, and acid mine drainage sample matrices using field and laboratory techniques are presented. The methods provide quantitative determination of arsenite [As(III)], arsenate [As(V)], monomethylarsonate (MMA), dimethylarsinate (DMA), and roxarsone in 2-8min at detection limits of less than 1??g arsenic per liter (??g AsL-1). All the methods use anion exchange chromatography to separate the arsenic species and inductively coupled plasma-mass spectrometry as an arsenic-specific detector. Different methods were needed because some sample matrices did not have all arsenic species present or were incompatible with particular high-performance liquid chromatography (HPLC) mobile phases. The bias and variability of the methods were evaluated using total arsenic, As(III), As(V), DMA, and MMA results from more than 100 surface-water, groundwater, and acid mine drainage samples, and reference materials. Concentrations in test samples were as much as 13,000??g AsL-1 for As(III) and 3700??g AsL-1 for As(V). Methylated arsenic species were less than 100??g AsL-1 and were found only in certain surface-water samples, and roxarsone was not detected in any of the water samples tested. The distribution of inorganic arsenic species in the test samples ranged from 0% to 90% As(III). Laboratory-speciation method variability for As(III), As(V), MMA, and DMA in reagent water at 0.5??g AsL-1 was 8-13% (n=7). Field-speciation method variability for As(III) and As(V) at 1??g AsL-1 in reagent water was 3-4% (n=3). ?? 2003 Elsevier Ltd. All rights reserved.

  7. Speciation and thermodynamic properties of zinc in sulfur-rich hydrothermal fluids: Insights from ab initio molecular dynamics simulations and X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Mei, Yuan; Etschmann, Barbara; Liu, Weihua; Sherman, David M.; Testemale, Denis; Brugger, Joël

    2016-04-01

    Chlorine and sulfur are the main elements involved in the complexing of metals in ore-forming fluids. The nature and thermodynamic properties of the Zn(II)-Cl complexes have been investigated by previous experimental and theoretical studies and are now well established up to high temperatures (600 °C). In contrast, the role of bisulfide complexes for zinc speciation in sulfur-bearing fluids remains poorly known, and a better understanding of Zn(II)-HS complexation is required for modeling zinc transport in magmatic and metamorphic fluids and for optimizing the hydrometallurgical processing of sulfide ores. We have conducted ab initio molecular dynamics (MD) simulations to calculate the speciation of Zn(II)-HS complexes from ambient to hydrothermal-magmatic conditions (25-600 °C, up to 2000 bar). These theoretical calculations were complemented by X-ray absorption spectroscopy (XAS) measurements of Zn(II) in HS--rich solutions at 200-500 °C and 600-1000 bar. The speciation and geometrical properties predicted by the ab initio MD simulations and the in situ XAS data are in excellent agreement. Upon heating from room temperature to 250 °C, Zn(II) speciation in HS--rich solutions shows a transition from the sixfold octahedral hexaaquo complex [Zn(H2O)6]2+ to fourfold tetrahedral [Zn(HS)n(H2O)4-n]2-n complexes (n = 1-4). Ab initio MD simulations also show that at temperatures > 250 °C, the threefold trigonal-planar [Zn(HS)3]- complex becomes increasingly stable, and predominates in S-rich solutions; in contrast, chloro-complexes display a tetrahedral geometry at 25-500 °C, while trigonal planar ZnCl3- predominates at temperatures > 500 °C. The stability constants of Zn(II)-HS complexes were calculated by thermodynamic integration of constrained ab initio MD simulations at 200, 350 and 600 °C. The stability constants generated from this study predict that zinc can be transported by HS- at high temperature in reduced, neutral to alkaline solutions, while Zn

  8. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    NASA Astrophysics Data System (ADS)

    Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2009-01-01

    Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included.

  9. Assessment of mercury speciation in feathers using species-specific isotope dilution analysis.

    PubMed

    Renedo, Marina; Bustamante, Paco; Tessier, Emmanuel; Pedrero, Zoyne; Cherel, Yves; Amouroux, David

    2017-11-01

    Seabirds are considered as effective sentinels of environmental marine contamination and their feathers are extensively used as non-lethal samples for contaminant biomonitoring. This tissue represents the main route for mercury (Hg) elimination in seabirds and contains predominantly methylmercury (MeHg). In this work, we developed a robust analytical technique for precise and accurate simultaneous quantification of MeHg, inorganic Hg (iHg) and consequently total Hg (THg), in feathers by gas-chromatography (GC)-ICPMS analyses using species-specific isotope dilution technique. An optimisation of the extraction method was carried out by testing different extraction systems, reagents and spiking procedures using an internal reference feather sample. The procedure was validated for MeHg and THg concentrations with a human hair certified reference material. Microwave nitric acid extraction with spike addition before the extraction provided the best recovery and was chosen as the most appropriate species simultaneous extraction method (SSE). An additional assessment was performed by comparison of our developed extraction method and a MeHg specific extraction technique (MSE) classically used for Hg speciation studies on feathers. The developed method was applied to feather samples from a large number of seabirds from the Southern Ocean (penguins, albatrosses, petrels and skuas) to investigate the variability of Hg speciation across a large range of Hg exposure conditions and concentrations. In all cases, MeHg accounted for > 90% of THg, thus verifying the predominance of organic Hg over iHg in feathers. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Combining selective sequential extractions, X-ray absorption spectroscopy, and principal component analysis for quantitative zinc speciation in soil.

    PubMed

    Scheinost, Andreas C; Kretzschmar, Ruben; Pfister, Sabina; Roberts, Darryl R

    2002-12-01

    Selective sequential extractions (SSE) and, more recently, X-ray absorption fine-structure IXAFS) spectroscopy have been used to characterize the speciation of metal contaminants in soils and sediments. However, both methods have specific limitations when multiple metal species coexist in soils and sediments. In this study, we tested a combined approach, in which XAFS spectra were collected after each of 6 SSE steps, and then analyzed by multishell fitting, principal component analysis (PCA) and linear combination fits (LCF), to determine the Zn speciation in a smelter-contaminated, strongly acidic soil. In the topsoil, Zn was predominately found in the smelter-emitted minerals franklinite (60%) and sphalerite (30%) and as aqueous or outer-sphere Zn2+ (10%). In the subsoil, aqueous or outer-sphere Zn2+ prevailed (55%), but 45% of Zn was incorporated by hydroxy-Al interlayers of phyllosilicates. Formation of such Zn-bearing hydroxy-interlayers, which has been observed here for the first time, may be an important mechanism to reduce the solubility of Zn in those soils, which are too acidic to retain Zn by formation of inner-sphere sorption complexes, layered double hydroxides or phyllosilicates. The stepwise removal of Zn fractions by SSE significantly improved the identification of species by XAFS and PCA and their subsequent quantification by LCF. While SSE alone provided excellent estimates of the amount of mobile Zn species, it failed to identify and quantify Zn associated with mineral phases because of nonspecific dissolution and the precipitation of Zn oxalate. The systematic combination of chemical extraction, spectroscopy, and advanced statistical analysis allowed us to identify and quantify both mobile and recalcitrant species with high reliability and precision.

  11. Arsenic speciation analysis of urine samples from individuals living in an arsenic-contaminated area in Bangladesh.

    PubMed

    Hata, Akihisa; Yamanaka, Kenzo; Habib, Mohamed Ahsan; Endo, Yoko; Fujitani, Noboru; Endo, Ginji

    2012-05-01

    Chronic inorganic arsenic (iAs) exposure currently affects tens of millions of people worldwide. To accurately determine the proportion of urinary arsenic metabolites in residents continuously exposed to iAs, we performed arsenic speciation analysis of the urine of these individuals and determined whether a correlation exists between the concentration of iAs in drinking water and the urinary arsenic species content. The subjects were 165 married couples who had lived in the Pabna District in Bangladesh for more than 5 years. Arsenic species were measured using high-performance liquid chromatography and inductively coupled plasma mass spectrometry. The median iAs concentration in drinking water was 55 μgAs/L (range <0.5-332 μgAs/L). Speciation analysis revealed the presence of arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid in urine samples with medians (range) of 16.8 (7.7-32.3), 1.8 (<0.5-3.3), 13.7 (5.6-25.0), and 88.6 μgAs/L (47.9-153.4 μgAs/L), respectively. No arsenobetaine or arsenocholine was detected. The concentrations of the 4 urinary arsenic species were significantly and linearly related to each other. The urinary concentrations of total arsenic and each species were significantly correlated with the iAs concentration of drinking water. All urinary arsenic species are well correlated with each other and with iAs in drinking water. The most significant linear relationship existed between the iAs concentration in drinking water and urinary iAs + MMA concentration. From these results, combined with the effects of seafood ingestion, the best biomarker of iAs exposure is urinary iAs + MMA concentration.

  12. Speciation in fungi.

    PubMed

    Giraud, Tatiana; Refrégier, Guislaine; Le Gac, Mickaël; de Vienne, Damien M; Hood, Michael E

    2008-06-01

    In this review on fungal speciation, we first contrast the issues of species definition and species criteria and show that by distinguishing the two concepts the approaches to studying the speciation can be clarified. We then review recent developments in the understanding of modes of speciation in fungi. Allopatric speciation raises no theoretical problem and numerous fungal examples exist from nature. We explain the theoretical difficulties raised by sympatric speciation, review the most recent models, and provide some natural examples consistent with speciation in sympatry. We describe the nature of prezygotic and postzygotic reproductive isolation in fungi and examine their evolution as functions of temporal and of the geographical distributions. We then review the theory and evidence for roles of cospeciation, host shifts, hybridization, karyotypic rearrangement, and epigenetic mechanisms in fungal speciation. Finally, we review the available data on the genetics of speciation in fungi and address the issue of speciation in asexual species.

  13. On-line speciation analysis of inorganic arsenic in complex environmental aqueous samples by pervaporation sequential injection analysis.

    PubMed

    Boonjob, Warunya; Miró, Manuel; Kolev, Spas D

    2013-12-15

    A proof of concept of a novel pervaporation sequential injection (PSI) analysis method for automatic non-chromatographic speciation analysis of inorganic arsenic in complex aqueous samples is presented. The method is based on hydride generation of arsine followed by its on-line pervaporation-based membrane separation and CCD spectrophotometric detection. The concentrations of arsenite (As(III)) and arsenate (As(V)) are determined sequentially in a single sample zone. The leading section of the sample zone merges with a citric acid/citrate buffer solution (pH 4.5) for the selective reduction of As(III) to arsine while the trailing section of the sample zone merges with hydrochloric acid solution to allow the reduction of both As(III) and As(V) to arsine at pH lower than 1. Virtually identical analytical sensitivity is obtained for both As(III) and As(V) at this high acidity. The flow analyzer also accommodates in-line pH detector for monitoring of the acidity throughout the sample zone prior to hydride generation. Under optimal conditions the proposed PSI method is characterized by a limit of detection, linear calibration range and repeatability for As(III) of 22 μg L(-1) (3sblank level criterion), 50-1000 μg L(-1) and 3.0% at the 500 μg L(-1) level and for As(V) of 51 μg L(-1), 100-2000 μg L(-1) and 2.6% at the 500 μg L(-1) level, respectively. The method was validated with mixed As(III)/As(V) standard aqueous solutions and successfully applied to the determination of As(III) and As(V) in river water samples with elevated content of dissolved organic carbon and suspended particulate matter with no prior sample pretreatment. Excellent relative recoveries ranging from 98% to 104% were obtained for both As(III) and As(V).

  14. Disequilibrium Experiments and Micro-XANES Analysis: Novel Tools to Unravel the Speciation of Sulfur in Silicate Melts.

    NASA Astrophysics Data System (ADS)

    Jugo, P. J.; Wilke, M.; Susini, J.

    2007-12-01

    Sulfur is an element of interest in magmatic processes for several reasons, some of which are related to the oxidation state of S during magma generation and evolution. For example, S as sulfide (S2-) controls the behavior of chalcophile and highly siderophile elements, whereas S as sulfate (S6+) is responsible for high- S explosive volcanic eruptions, which can cause global cooling by increasing the Earth's albedo. An adequate understanding of the speciation of S in magmatic systems and the transition from S2- to S6+ is therefore needed to understand these processes. Data from natural samples is incomplete and experimental data are required to link natural data with oxygen fugacity (fO2). However, the change in speciation from sulfide to sulfate in silicate melts is difficult to simulate experimentally because: (a) common capsule materials react with S (e.g. Pt) or have low melting points (e.g. Au); (b) the change in speciation occurs over a very narrow fO2 interval (FMQ to FMQ+2) and common buffering techniques (e.g. "double capsule" technique with FMQ or NNO buffers) are not sufficient to investigate a wide-enough range in fO2; (c) sulfur solubility in silicate melts in the fO2 range of interest is too low at atmospheric pressures, limiting the use of gas-mixing furnaces to either very oxidized or very reduced conditions. We have used disequilibrium experiments in which sulfate-saturated (i.e. oxidized) basaltic and andesitic melts were reacted with graphite (a reductant) and quenched before the system reached equilibrium. Quenching of the experiments before complete re-equilibration (i.e. complete reduction by graphite) preserved reduction profiles in which sulfate-saturated glass (in the center of the capsule) coexisted with sulfide-saturated glass (at the edge of graphite capsule). We used the ID-21 beamline at the European Synchrotron Radiation Facility (ESRF) to perform micro-XANES analysis at the S K- edge to determine the speciation of sulfur along the

  15. Investigating syn- vs. post-eruption hydration mechanisms of the 2012 Havre submarine explosive eruption: Water speciation analysis of pumiceous rhyolitic glass

    NASA Astrophysics Data System (ADS)

    Mitchell, S. J.; McIntosh, I. M.; Houghton, B. F.; Shea, T.; Carey, R.

    2016-12-01

    Volatiles preserved in volcanic glass can record the quenching, fragmentation and solubility conditions during an explosive eruption. The VEI-5 2012 eruption of Havre volcano, which produced >1.5 km3 of rhyolite, provides exciting new insight into deep-submarine explosive eruptions. With no direct observations of the eruption at the 900 mbsl vent, the analysis and interpretation of volatile concentrations and speciation within pyroclasts is essential to constraining the eruption style and quenching mechanisms in this understudied environment. We present here the first detailed water speciation data for a large submarine explosive eruption. Water concentrations were measured in pyroclasts from known deposit localities across the Havre stratigraphic succession after ROV collection in 2015. Variations in total water concentration (H2OT) within pyroclasts were determined using high spatial resolution (1 - 2 µm) micro-Raman spectroscopy and water speciation (molecular water (H2Om) and OH) concentrations were measured using Fourier-transform infrared spectroscopy. H2OT concentrations are consistent between Raman and FTIR analysis, ranging from 0.1 - 1.5 wt % H2OT over different stratigraphic units. Comparison of water speciation data with speciation models suggests the Havre pyroclasts experienced secondary, non-magmatic hydration. Since OH is unaltered by secondary hydration, OH concentrations aid in the interpretation of quench depths and inferring of eruption mechanisms. The variability of excess H2Om across units suggests a more complex glass-hydration mechanism during the eruption instead of exclusively post-eruption, low-temperature secondary rehydration. The young sample ages are inconsistent with our current understanding of low-temperature H2O-diffusivity timescales, implying faster secondary rehydration in a higher-temperature submarine setting. We here explore potentially novel syn-eruptive, higher-temperature hydration mechanisms for deep-submarine pumice.

  16. [Application of bionic technology to speciation analysis and bioavailability assessment of nickel in transgenic soybean].

    PubMed

    Chen, Li-Hui; Li, Shun-Xing; Mou, Yang; Zheng, Feng-Ying; Li, Yan-Cai; Wang, Hui; Zheng, Na-Yan; Xie, He-Fang

    2013-11-01

    The safety of transgenic food has been paid the most attention to by the public and scientists. Trace metal bioavailability could provide information for safety assessment of transgenic food. The critical functional digestion and absorption in the gastrointestinal tract were simulated by bionic gastrointestinal digestion, metabolism of gut microbiota, and bionic biomembrane adsorption with liposome and then used for the pretreatment of transgenic and general soybeans. Ni speciation in the chyme was defined as affinity-liposome and water soluble Ni. Nickel bioavailability was assessed by the content of affinity-liposome Ni. Water soluble Ni was the main species of nickel complex in the chyme. Nickel bioavailability was 4.1% for transgenic soybean and 3.3% for general soybean, which could be enhanced by gastrointestinal digestion and metabolism of gut microbiota. After transgene, nickel bioavailability was increased 24% but the content of affinity-liposome Ni was 122.3 ng x g(-1) for transgenic soybean, just as 36% as that of general soybean.

  17. A sensitive flow-based procedure for spectrophotometric speciation analysis of inorganic bromine in waters.

    PubMed

    Rocha, Diogo L; Machado, Marcos C; Melchert, Wanessa R

    2014-11-01

    A flow-based system with solenoid micro-pumps and long path-length spectrophotometry for bromate and bromide determination in drinking water is proposed. The method is based on the formation of an unstable dye from the reaction between bromate, 2-(5-dibromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) and thiocyanate ions. A multivariate optimization was carried out. A linear response was observed between 5.0 and 100 µg L(-1) BrO3(-) and the detection limit was estimated as 2.0 µg L(-1) (99.7% confidence level). The coefficient of variation (n=20) and sampling rate were estimated as 1.0% and 40 determinations per hour, respectively. Reagent consumption was estimated as 0.17 µg of 5-Br-PADAP and 230 μg of NaSCN per measurement, generating 6.0 mL of waste. Bromide determination was carried out after UV-assisted conversion with K2S2O8 using 300 µL of sample within the range 20-400 µg L(-1) Br(-). The generated bromate was then determined by the proposed flow system. The results for tap and commercial mineral water samples agreed with those obtained with the reference procedure at the 95% confidence level. The proposed procedure is therefore a sensitive, environmentally friendly and reliable alternative for inorganic bromine speciation.

  18. Occurrence and chemical speciation analysis of organotin compounds in the environment: a review.

    PubMed

    de Carvalho Oliveira, Regina; Santelli, Ricardo Erthal

    2010-06-30

    Environmental concerns regarding organotin compounds have increased remarkably in the past 20 years, due in large part to the use of these compounds as active components in antifouling paints [mainly tributyltin (TBT)] and pesticide formulations [mainly triphenyltin (TPhT)]. Their direct introduction into the environment, their bio-accumulation and the high toxicity of these compounds towards "non-target" organisms (for example: oysters and mussels) causes environmental and economic damage around the world. As a consequence, the presence and absence of organotin compounds is currently monitored in a range of environmental matrices (e.g., water, sediment and shellfish) to examine the utility of controls meant to regulate the level of contamination as required in some EC Directives and the Water Framework Directive 2000/60/EC. To evaluate the environmental distribution and fate of these compounds and to determine the effectives of legal provisions adopted by a number of countries, a variety of analytical methods have been developed for organotin determination in the environment. Most of these methods include different steps such as extraction, derivatisation and clean up. The aim of the present review is to evaluate the environmental distribution, fate and chemical speciation of organotin compounds in the environment.

  19. Real-time analysis of total, elemental, and total speciated mercury

    SciTech Connect

    Schlager, R.J.; Wilson, K.G.; Sappey, A.D.

    1995-11-01

    ADA Technologies, Inc., is developing a continuous emissions monitoring system that measures the concentrations of mercury in flue gas. Mercury is emitted as an air pollutant from a number of industrial processes. The largest contributors of these emissions are coal and oil combustion, municipal waste combustion, medical waste combustion, and the thermal treatment of hazardous materials. It is difficult, time consuming, and expensive to measure mercury emissions using current testing methods. Part of the difficulty lies in the fact that mercury is emitted from sources in several different forms, such as elemental mercury and mercuric chloride. The ADA analyzer measures these emissions in real time, thus providing a number of advantages over existing test methods: (1) it will provide a real-time measure of emission rates, (2) it will assure facility operators, regulators, and the public that emissions control systems are working at peak efficiency, and (3) it will provide information as to the nature of the emitted mercury (elemental mercury or speciated compounds). This update presents an overview of the CEM and describes features of key components of the monitoring system--the mercury detector, a mercury species converter, and the analyzer calibration system.

  20. Multigene analysis suggests ecological speciation in the fungal pathogen Claviceps purpurea

    PubMed Central

    DOUHAN, G. W.; SMITH, M. E.; HUYRN, K. L.; WESTBROOK, A.; Beerli, P.; FISHER, A. J.

    2008-01-01

    Claviceps purpurea is an important pathogen of grasses and source of novel chemical compounds. Three groups within this species (G1, G2, and G3) have been recognized based on habitat association, sclerotia and conidia morphology, and alkaloid production. These groups have further been supported by RAPD and AFLP markers, suggesting this species may be more accurately described as a species complex. However, all divergent ecotypes can coexist in sympatric populations with no obvious physical barriers to prevent gene flow. In this study, we used both phylogenetic and population genetic analyses to test for speciation within C. purpurea using DNA sequences from ITS, a RAS-like locus, and a portion of beta-tubulin. The G1 types are significantly divergent from the G2/G3 types based on each of the three loci and the combined dataset, whereas the G2/G3 types are more integrated with one another. Although the G2 and G3 lineages have not diverged as much as the G1 lineage based on DNA sequence data, the use of three DNA loci does reliably separate the G2 and G3 lineages. However, the population genetic analyses strongly suggest little to no gene flow occurring between the different ecotypes and we argue that this process is driven by adaptations to ecological habitats; G1 isolates are associated with terrestrial grasses, G2 isolates are found in wet and shady environments, and G3 isolates are found in salt marsh habitats. PMID:18373531

  1. Speciation in fishes.

    PubMed

    Bernardi, Giacomo

    2013-11-01

    The field of speciation has seen much renewed interest in the past few years, with theoretical and empirical advances that have moved it from a descriptive field to a predictive and testable one. The goal of this review is to provide a general background on research on speciation as it pertains to fishes. Three major components to the question are first discussed: the spatial, ecological and sexual factors that influence speciation mechanisms. We then move to the latest developments in the field of speciation genomics. Affordable and rapidly available, massively parallel sequencing data allow speciation studies to converge into a single comprehensive line of investigation, where the focus has shifted to the search for speciation genes and genomic islands of speciation. We argue that fish present a very diverse array of scenarios, making them an ideal model to study speciation processes.

  2. Speciation analysis of inorganic antimony in sediment samples from São Paulo Estuary, Bahia State, Brazil.

    PubMed

    Silva, Mario Marques; Leao, Danilo Junqueira; Moreira, Ícaro Thiago Andrade; de Oliveira, Olívia Maria Cordeiro; de Souza Queiroz, Antônio Fernando; Ferreira, Sergio Luis Costa

    2015-06-01

    This paper proposes an extraction procedure for the speciation analysis of inorganic antimony in sediment samples using slurry sampling and hydride generation atomic absorption spectrometry. The optimization step of extraction of the species was performed employing a full two-level factorial design (2(3)) and a Box-Behnken matrix where the studied factors in both experiments were: extraction temperature, ultrasonic radiation time, and hydrochloric acid concentration. Using the optimized conditions, antimony species can be extracted in closed system using a 6.0 M hydrochloric acid solution at temperature of 70 °C and an ultrasonic radiation time of 20 min. The determination of antimony is performed in presence of 2.0 M hydrochloric acid solution using HG AAS by external calibration technique with limits of detection and quantification of 5.6 and 19.0 ng L(-1) and a precision expressed as relative standard deviation of 5.6 % for an antimony solution with concentration of 6.0 μg L(-1). The accuracy of the method was confirmed by analysis of two certified reference materials of sediments. For a sample mass of sediment of 0.20 g, the limits of detection and quantification obtained were 0.70 and 2.34 ng g(-1), respectively. During speciation analysis, antimony(III) is determined in presence of citrate, while total antimony is quantified after reduction of antimony(V) to antimony(III) using potassium iodide and ascorbic acid. The method was applied for analysis of six sediment samples collected in São Paulo Estuary (Bahia State, Brazil). The antimony contents obtained varied from 45.3 to 89.1 ng g(-1) for total antimony and of 17.7 to 31.4 ng g(-1) for antimony(III). These values are agreeing with other data reported by the literature for this element in uncontaminated sediment samples.

  3. Operational Dynamic Configuration Analysis

    NASA Technical Reports Server (NTRS)

    Lai, Chok Fung; Zelinski, Shannon

    2010-01-01

    Sectors may combine or split within areas of specialization in response to changing traffic patterns. This method of managing capacity and controller workload could be made more flexible by dynamically modifying sector boundaries. Much work has been done on methods for dynamically creating new sector boundaries [1-5]. Many assessments of dynamic configuration methods assume the current day baseline configuration remains fixed [6-7]. A challenging question is how to select a dynamic configuration baseline to assess potential benefits of proposed dynamic configuration concepts. Bloem used operational sector reconfigurations as a baseline [8]. The main difficulty is that operational reconfiguration data is noisy. Reconfigurations often occur frequently to accommodate staff training or breaks, or to complete a more complicated reconfiguration through a rapid sequence of simpler reconfigurations. Gupta quantified a few aspects of airspace boundary changes from this data [9]. Most of these metrics are unique to sector combining operations and not applicable to more flexible dynamic configuration concepts. To better understand what sort of reconfigurations are acceptable or beneficial, more configuration change metrics should be developed and their distribution in current practice should be computed. This paper proposes a method to select a simple sequence of configurations among operational configurations to serve as a dynamic configuration baseline for future dynamic configuration concept assessments. New configuration change metrics are applied to the operational data to establish current day thresholds for these metrics. These thresholds are then corroborated, refined, or dismissed based on airspace practitioner feedback. The dynamic configuration baseline selection method uses a k-means clustering algorithm to select the sequence of configurations and trigger times from a given day of operational sector combination data. The clustering algorithm selects a simplified

  4. SPECIATE - EPA'S DATABASE OF SPECIATED EMISSION PROFILES

    EPA Science Inventory

    SPECIATE is the U.S. Environmental Protection Agency's (EPA) repository of total organic compound (TOC) and particulate matter (PM) speciation profiles for emissions from air pollution sources. The data base has recently been updated and an associated report has recently been re...

  5. SPECIATE - EPA'S DATABASE OF SPECIATED EMISSION PROFILES

    EPA Science Inventory

    SPECIATE is the U.S. Environmental Protection Agency's (EPA) repository of total organic compound (TOC) and particulate matter (PM) speciation profiles for emissions from air pollution sources. The data base has recently been updated and an associated report has recently been re...

  6. Advances in analytical methodology for bioinorganic speciation analysis: metallomics, metalloproteomics and heteroatom-tagged proteomics and metabolomics.

    PubMed

    Szpunar, Joanna

    2005-04-01

    The recent developments in analytical techniques capable of providing information on the identity and quantity of heteroatom-containing biomolecules are critically discussed. Particular attention is paid to the emerging areas of bioinorganic analysis including: (i) a comprehensive analysis of the entirety of metal and metalloid species within a cell or tissue type (metallomics), (ii) the study of the part of the metallome involving the protein ligands (metalloproteomics), and (iii) the use of a heteroelement, naturally present in a protein or introduced in a tag added by means of derivatisation, for the spotting and quantification of proteins (heteroatom-tagged proteomics). Inductively coupled plasma mass spectrometry (ICP MS), used as detector in chromatography and electrophoresis, and supported by electrospray and MALDI MS, appears as the linchpin analytical technique for these emerging areas. This review focuses on the recent advances in ICP MS in biological speciation analysis including sensitive detection of non-metals, especially of sulfur and phosphorus, couplings to capillary and nanoflow HPLC and capillary electrophoresis, laser ablation ICP MS detection of proteins in gel electrophoresis, and isotope dilution quantification of biomolecules. The paper can be considered as a followup of a previous review by the author on a similar topic (J. Szpunar, Analyst, 2000, 125, 963).

  7. Iron Speciation in Urban Dust

    SciTech Connect

    E Elzinga; Y Gao; J Fitts; R Tappero

    2011-12-31

    An improved understanding of anthropogenic impacts on ocean fertility requires knowledge of anthropogenic dust mineralogy and associated Fe speciation as a critical step toward developing Fe solubility models constrained by mineralogical composition. This study explored the utility of micro-focused X-ray absorption spectroscopy ({mu}-XAS) in characterizing the speciation of Fe in urban dust samples. A micro-focused beam of 10 x 7 {micro}m made possible the measurement of the Fe K edge XAS spectra of individual dust particles in the PM5.6 size fraction collected in Newark, New Jersey, USA. Spectral analysis indicated the presence of mixtures of Fe-containing minerals within individual dust particles; we observed significant magnetite content along with other Fe(III)-(hydr)oxide minerals which could not be conclusively identified. Our data indicate that detailed quantitative determination of Fe speciation requires extended energy scans to constrain the types and relative abundance of Fe species present. We observe heterogeneity in Fe speciation at the dust particle level, which underscores the importance of analyzing a statistically adequate number of particles within each dust sample. Where possible, {mu}-XAS measurements should be complemented with additional characterization techniques such as {mu}-XRD and bulk XAS to obtain a comprehensive picture of the Fe speciation in dust materials. X-ray microprobes should be used to complement bulk methods used to determine particle composition, methods that fail to record particle heterogeneity.

  8. 3D printed device including disk-based solid-phase extraction for the automated speciation of iron using the multisyringe flow injection analysis technique.

    PubMed

    Calderilla, Carlos; Maya, Fernando; Cerdà, Víctor; Leal, Luz O

    2017-12-01

    The development of advanced manufacturing techniques is crucial for the design of novel analytical tools with unprecedented features. Advanced manufacturing, also known as 3D printing, has been explored for the first time to fabricate modular devices with integrated features for disk-based automated solid-phase extraction (SPE). A modular device integrating analyte oxidation, disk-based SPE and analyte complexation has been fabricated using stereolithographic 3D printing. The 3D printed device is directly connected to flow-based analytical instrumentation, replacing typical flow networks based on discrete elements. As proof of concept, the 3D printed device was implemented in a multisyringe flow injection analysis (MSFIA) system, and applied to the fully automated speciation, SPE and spectrophotometric quantification of Fe in water samples. The obtained limit of detection for total Fe determination was 7ng, with a dynamic linear range from 22ng to 2400ng Fe (3mL sample). An intra-day RSD of 4% (n = 12) and an inter-day RSD of 4.3% (n = 5, 3mL sample, different day with a different disk), were obtained. Incorporation of integrated 3D printed devices with automated flow-based techniques showed improved sensitivity (85% increase on the measured peak height for the determination of total Fe) in comparison with analogous flow manifolds built from conventional tubing and connectors. Our work represents a step forward towards the improved reproducibility in the fabrication of manifolds for flow-based automated methods of analysis, which is especially relevant in the implementation of interlaboratory analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Fluoride and iodine enrichment in groundwater of North China Plain: Evidences from speciation analysis and geochemical modeling.

    PubMed

    Li, Junxia; Zhou, Hailing; Qian, Kun; Xie, Xianjun; Xue, Xiaobin; Yang, Yijun; Wang, Yanxin

    2017-11-15

    To better understand the enrichment of fluoride and iodine in groundwater at North China Plain (NCP), speciation analysis and geochemical modeling were conducted to identify the key hydrochemical processes controlling their mobilization in groundwater system. Groundwater fluoride and iodine concentrations ranged from 0.18 to 5.59mg/L and from 1.51 to 1106μg/L, respectively, and approximately 63% and 32.3% of groundwater fluoride and iodine were higher than the guidelines for drinking water (1.5mg/L and 150μg/L). High fluoride concentration (>1.5mg/L) can be detected in groundwater from the flow-through and discharge areas of NCP, and high iodine groundwater (>150μg/L) is mainly scattered in the coastal area. Na-HCO3/Cl type water resulted from water-rock interaction and seawater intrusion favors fluoride and iodine enrichment in groundwater. Speciation analysis results indicate that (1) fluoride complexes in groundwater are dominated by free fluoride, the negative charge of which favors fluoride enrichment in groundwater under basic conditions, and (2) iodide, iodate and organic iodine co-occur in groundwater at NCP with iodide as the dominant species. The geochemical modeling results indicate that groundwater fluoride is mainly associated with the saturation states of fluorite and calcite, as well as the adsorption equilibrium onto goethite and gibbsite, including the competitive adsorption between fluoride and carbonate. Groundwater iodine is mainly controlled by redox potential and pH condition of groundwater system. Reducing condition favors the mobilization and enrichment of groundwater iodide, which has the highest mobility among iodine species. Under reducing condition, reductive dissolution of iron (oxy)hydroxides is a potential geochemical process responsible for iodine release from sediment into groundwater. Under (sub)oxidizing condition, as groundwater pH over the 'point of zero charge' of iron (oxy)hydroxides, the lowering adsorption capacity of

  10. Population Genomic Analysis Reveals a Rich Speciation and Demographic History of Orang-utans (Pongo pygmaeus and Pongo abelii)

    PubMed Central

    Ma, Xin; Kelley, Joanna L.; Eilertson, Kirsten; Musharoff, Shaila; Degenhardt, Jeremiah D.; Martins, André L.; Vinar, Tomas; Kosiol, Carolin; Siepel, Adam; Gutenkunst, Ryan N.; Bustamante, Carlos D.

    2013-01-01

    To gain insights into evolutionary forces that have shaped the history of Bornean and Sumatran populations of orang-utans, we compare patterns of variation across more than 11 million single nucleotide polymorphisms found by previous mitochondrial and autosomal genome sequencing of 10 wild-caught orang-utans. Our analysis of the mitochondrial data yields a far more ancient split time between the two populations (∼3.4 million years ago) than estimates based on autosomal data (0.4 million years ago), suggesting a complex speciation process with moderate levels of primarily male migration. We find that the distribution of selection coefficients consistent with the observed frequency spectrum of autosomal non-synonymous polymorphisms in orang-utans is similar to the distribution in humans. Our analysis indicates that 35% of genes have evolved under detectable negative selection. Overall, our findings suggest that purifying natural selection, genetic drift, and a complex demographic history are the dominant drivers of genome evolution for the two orang-utan populations. PMID:24194868

  11. Population genomic analysis reveals a rich speciation and demographic history of orang-utans (Pongo pygmaeus and Pongo abelii).

    PubMed

    Ma, Xin; Kelley, Joanna L; Eilertson, Kirsten; Musharoff, Shaila; Degenhardt, Jeremiah D; Martins, André L; Vinar, Tomas; Kosiol, Carolin; Siepel, Adam; Gutenkunst, Ryan N; Bustamante, Carlos D

    2013-01-01

    To gain insights into evolutionary forces that have shaped the history of Bornean and Sumatran populations of orang-utans, we compare patterns of variation across more than 11 million single nucleotide polymorphisms found by previous mitochondrial and autosomal genome sequencing of 10 wild-caught orang-utans. Our analysis of the mitochondrial data yields a far more ancient split time between the two populations (~3.4 million years ago) than estimates based on autosomal data (0.4 million years ago), suggesting a complex speciation process with moderate levels of primarily male migration. We find that the distribution of selection coefficients consistent with the observed frequency spectrum of autosomal non-synonymous polymorphisms in orang-utans is similar to the distribution in humans. Our analysis indicates that 35% of genes have evolved under detectable negative selection. Overall, our findings suggest that purifying natural selection, genetic drift, and a complex demographic history are the dominant drivers of genome evolution for the two orang-utan populations.

  12. Flow Injection Photochemical Vapor Generation Coupled with Miniaturized Solution-Cathode Glow Discharge Atomic Emission Spectrometry for Determination and Speciation Analysis of Mercury.

    PubMed

    Mo, Jiamei; Li, Qing; Guo, Xiaohong; Zhang, Guoxia; Wang, Zheng

    2017-09-15

    A novel, compact, and green method was developed for the determination and speciation analysis of mercury, based on flow injection photochemical vapor generation (PVG) coupled with miniaturized solution cathode glow discharge-atomic emission spectroscopy (SCGD-AES). The SCGD was generated between a miniature hollow titanium tube and a solution emerging from a glass capillary. Cold mercury vapor (Hg(0)) was generated by PVG and subsequently delivered to the SCGD for excitation, and finally the emission signals were recorded by a miniaturized spectrograph. The detection limits (DLs) of Hg(II) and methylmercury (MeHg) were both determined to be 0.2 μg L(-1). Moreover, mercury speciation analysis could also be performed by using different wavelengths and powers from the UV lamp and irradiation times. Both Hg(II) and MeHg can be converted to Hg(0) for the determination of total mercury (T-Hg) with 8 W/254 nm UV lamp and 60 s irradiation time; while only Hg(II) can be reduced to Hg(0) and determined selectively with 4 W/365 nm UV lamp and 20 s irradiation time. Then, the concentration of MeHg can be calculated by subtracting the Hg(II) from the T-Hg. Because of its similar sensitivity and DL at 8 W/254 nm, the simpler and less toxic Hg(II) was used successfully as a primary standard for the quantification of T-Hg. The novel PVG-SCGD-AES system provides not only a 365-fold improvement in the DL for Hg(II) but also a nonchromatographic method for the speciation analysis of mercury. After validating its accuracy, this method was successfully used for mercury speciation analysis of water and biological samples.

  13. Speciation genetics: current status and evolving approaches.

    PubMed

    Wolf, Jochen B W; Lindell, Johan; Backström, Niclas

    2010-06-12

    The view of species as entities subjected to natural selection and amenable to change put forth by Charles Darwin and Alfred Wallace laid the conceptual foundation for understanding speciation. Initially marred by a rudimental understanding of hereditary principles, evolutionists gained appreciation of the mechanistic underpinnings of speciation following the merger of Mendelian genetic principles with Darwinian evolution. Only recently have we entered an era where deciphering the molecular basis of speciation is within reach. Much focus has been devoted to the genetic basis of intrinsic postzygotic isolation in model organisms and several hybrid incompatibility genes have been successfully identified. However, concomitant with the recent technological advancements in genome analysis and a newfound interest in the role of ecology in the differentiation process, speciation genetic research is becoming increasingly open to non-model organisms. This development will expand speciation research beyond the traditional boundaries and unveil the genetic basis of speciation from manifold perspectives and at various stages of the splitting process. This review aims at providing an extensive overview of speciation genetics. Starting from key historical developments and core concepts of speciation genetics, we focus much of our attention on evolving approaches and introduce promising methodological approaches for future research venues.

  14. Speciation genetics: current status and evolving approaches

    PubMed Central

    Wolf, Jochen B. W.; Lindell, Johan; Backström, Niclas

    2010-01-01

    The view of species as entities subjected to natural selection and amenable to change put forth by Charles Darwin and Alfred Wallace laid the conceptual foundation for understanding speciation. Initially marred by a rudimental understanding of hereditary principles, evolutionists gained appreciation of the mechanistic underpinnings of speciation following the merger of Mendelian genetic principles with Darwinian evolution. Only recently have we entered an era where deciphering the molecular basis of speciation is within reach. Much focus has been devoted to the genetic basis of intrinsic postzygotic isolation in model organisms and several hybrid incompatibility genes have been successfully identified. However, concomitant with the recent technological advancements in genome analysis and a newfound interest in the role of ecology in the differentiation process, speciation genetic research is becoming increasingly open to non-model organisms. This development will expand speciation research beyond the traditional boundaries and unveil the genetic basis of speciation from manifold perspectives and at various stages of the splitting process. This review aims at providing an extensive overview of speciation genetics. Starting from key historical developments and core concepts of speciation genetics, we focus much of our attention on evolving approaches and introduce promising methodological approaches for future research venues. PMID:20439277

  15. Dynamical pathway analysis

    PubMed Central

    Xiong, Hao; Choe, Yoonsuck

    2008-01-01

    Background Although a great deal is known about one gene or protein and its functions under different environmental conditions, little information is available about the complex behaviour of biological networks subject to different environmental perturbations. Observing differential expressions of one or more genes between normal and abnormal cells has been a mainstream method of discovering pertinent genes in diseases and therefore valuable drug targets. However, to date, no such method exists for elucidating and quantifying the differential dynamical behaviour of genetic regulatory networks, which can have greater impact on phenotypes than individual genes. Results We propose to redress the deficiency by formulating the functional study of biological networks as a control problem of dynamical systems. We developed mathematical methods to study the stability, the controllability, and the steady-state behaviour, as well as the transient responses of biological networks under different environmental perturbations. We applied our framework to three real-world datasets: the SOS DNA repair network in E. coli under different dosages of radiation, the GSH redox cycle in mice lung exposed to either poisonous air or normal air, and the MAPK pathway in mammalian cell lines exposed to three types of HIV type I Vpr, a wild type and two mutant types; and we found that the three genetic networks exhibited fundamentally different dynamical properties in normal and abnormal cells. Conclusion Difference in stability, relative stability, degrees of controllability, and transient responses between normal and abnormal cells means considerable difference in dynamical behaviours and different functioning of cells. Therefore differential dynamical properties can be a valuable tool in biomedical research. PMID:18221557

  16. Ultrasensitive Speciation Analysis of Mercury in Rice by Headspace Solid Phase Microextraction Using Porous Carbons and Gas Chromatography-Dielectric Barrier Discharge Optical Emission Spectrometry.

    PubMed

    Lin, Yao; Yang, Yuan; Li, Yuxuan; Yang, Lu; Hou, Xiandeng; Feng, Xinbin; Zheng, Chengbin

    2016-03-01

    Rice consumption is a primary pathway for human methylmercury (MeHg) exposure in inland mercury mining areas of Asia. In addition, the use of iodomethane, a common fumigant that significantly accelerates the methylation of mercury in soil under sunlight, could increase the MeHg exposure from rice. Conventional hyphenated techniques used for mercury speciation analysis are usually too costly for most developing countries. Consequently, there is an increased interest in the development of sensitive and inexpensive methods for the speciation of mercury in rice. In this work, gas chromatography (GC) coupled to dielectric barrier discharge optical emission spectrometry (DBD-OES) was developed for the speciation analysis of mercury in rice. Prior to GC-DBD-OES analysis, mercury species were derivatized to their volatile species with NaBPh4 and preconcentrated by headspace solid phase microextraction using porous carbons. Limits of detection of 0.5 μg kg(-1) (0.16 ng), 0.75 μg kg(-1) (0.24 ng), and 1.0 μg kg(-1) (0.34 ng) were obtained for Hg(2+), CH3Hg(+), and CH3CH2Hg(+), respectively, with relative standard deviations (RSDs) better than 5.2% and 6.8% for one fiber or fiber-to-fiber mode, respectively. Recoveries of 90-105% were obtained for the rice samples, demonstrating the applicability of the proposed technique. Owing to the small size, low power, and low gas consumption of DBD-OES as well as efficient extraction of mercury species by porous carbons headspace solid phase micro-extraction, the proposed technique provides several advantages including compactness, cost-effectiveness, and potential to couple with miniature GC to accomplish the field speciation of mercury in rice compared to conventional hyphenated techniques.

  17. Speciation analysis of antimony in extracts of size-classified volcanic ash by HPLC-ICP-MS.

    PubMed

    Miravet, R; López-Sánchez, J F; Rubio, R; Smichowski, P; Polla, G

    2007-03-01

    Although there is concern about the presence of toxic elements and their species in environmental matrices, for example water, sediment, and soil, speciation analysis of volcanic ash has received little attention. Antimony, in particular, an emerging element of environmental concern, has been less studied than other potentially toxic trace elements. In this context, a study was undertaken to assess the presence of inorganic Sb species in ash emitted from the Copahue volcano (Argentina). Antimony species were extracted from size-classified volcanic ash (<36 microm, 35-45 microm, 45-150 microm, and 150-300 microm) by use of 1 mol L(-1) citrate buffer at pH 5. Antimony(III) and (V) in the extracts were separated and quantified by high-performance liquid chromatography combined on-line with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Antimony species concentrations (microg g(-1)) in the four fractions varied from 0.14 to 0.67 for Sb(III) and from 0.02 to 0.03 for Sb(V). The results reveal, for the first time, the occurrence of both inorganic Sb species in the extractable portion of volcanic ash. Sb(III) was always the predominant species.

  18. Inorganic selenium speciation analysis in Allium and Brassica vegetables by ionic liquid assisted liquid-liquid microextraction with multivariate optimization.

    PubMed

    Castro Grijalba, Alexander; Martinis, Estefanía M; Wuilloud, Rodolfo G

    2017-03-15

    A highly sensitive vortex assisted liquid-liquid microextraction (VA-LLME) method was developed for inorganic Se [Se(IV) and Se(VI)] speciation analysis in Allium and Brassica vegetables. Trihexyl(tetradecyl)phosphonium decanoate phosphonium ionic liquid (IL) was applied for the extraction of Se(IV)-ammonium pyrrolidine dithiocarbamate (APDC) complex followed by Se determination with electrothermal atomic absorption spectrometry. A complete optimization of the graphite furnace temperature program was developed for accurate determination of Se in the IL-enriched extracts and multivariate statistical optimization was performed to define the conditions for the highest extraction efficiency. Significant factors of IL-VA-LLME method were sample volume, extraction pH, extraction time and APDC concentration. High extraction efficiency (90%), a 100-fold preconcentration factor and a detection limit of 5.0ng/L were achieved. The high sensitivity obtained with preconcentration and the non-chromatographic separation of inorganic Se species in complex matrix samples such as garlic, onion, leek, broccoli and cauliflower, are the main advantages of IL-VA-LLME. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Inductively coupled plasma mass spectrometric detection for multielement flow injection analysis and elemental speciation by reversed-phase liquid chromatography

    SciTech Connect

    Thompson, J.J.; Houk, R.S.

    1986-10-01

    The feasibility of using an inductively coupled plasma mass spectrometer as a multielement detector for flow injection analysis (FIA) and ion-pair reversed-phase liquid chromatography was investigated. Sample introduction was by ultrasonic nebulization with aerosol desolvation. Absolute detection limits for FIA ranged from 0.01 to 0.1 ng for most elements using 10-..mu..L injection. Over 30 elements were surveyed for their response to both anionic and cationic ion pairing reagents. The separation and selective detection of various As and Se species were demonstrated, yielding detection limits near 0.1 ng (as element) for all six species present. Determination of 15 elements in a single injection with multiple ion monitoring produced similar detection limits. Isotope ratios were measured with sufficient precision (better than 2%) and accuracy (about 1%) on eluting peaks of Cd and Pb to demonstrate that liquid chromatography/inductively coupled plasma mass spectrometry should make speciation studies with stable tracer isotopes feasible.

  20. Tracing gadolinium-based contrast agents from surface water to drinking water by means of speciation analysis.

    PubMed

    Birka, Marvin; Wehe, Christoph A; Hachmöller, Oliver; Sperling, Michael; Karst, Uwe

    2016-04-01

    In recent decades, a significant amount of anthropogenic gadolinium has been released into the environment as a result of the broad application of contrast agents for magnetic resonance imaging (MRI). Since this anthropogenic gadolinium anomaly has also been detected in drinking water, it has become necessary to investigate the possible effect of drinking water purification on these highly polar microcontaminats. Therefore, a novel highly sensitive method for speciation analysis of gadolinium is presented. For that purpose, the hyphenation of hydrophilic interaction liquid chromatography (HILIC) and inductively coupled plasma-mass spectrometry (ICP-MS) was employed. In order to enhance the detection power, sample introduction was carried out by ultrasonic nebulization. In combination with a novel HILIC method using a diol-based stationary phase, it was possible to achieve superior limits of detection for frequently applied gadolinium-based contrast agents below 20pmol/L. With this method, the contrast agents Gd-DTPA, Gd-DOTA and Gd-BT-DO3A were determined in concentrations up to 159pmol/L in samples from several waterworks in a densely populated region of Germany alongside the river Ruhr as well as from a waterworks near a catchment lake. Thereby, the direct impact of anthropogenic gadolinium species being present in the surface water on the amount of anthropogenic gadolinium in drinking water was shown. There was no evidence for the degradation of contrast agents, the release of Gd(3+) or the presence of further Gd species.

  1. Measurement, time series analysis and source apportionment of inorganic and organic speciated PM(2.5) air pollution in Denver

    NASA Astrophysics Data System (ADS)

    Dutton, Steven James

    Particulate air pollution has demonstrated significant health effects ranging from worsening of asthma to increased rates of respiratory and cardiopulmonary mortality. These results have prompted the US-EPA to include particulate matter (PM) as one of the six criteria air pollutants regulated under the Clean Air Act. The diverse chemical make-up and physical characteristics of PM make it a challenging pollutant to characterize and regulate. Particulate matter less than 2.5 microns in diameter (PM2.5) has the ability to travel deep into the lungs and therefore has been linked with some of the more significant health effects. The toxicity of any given particle is likely dependent on its chemical composition. The goal of this project has been to chemically characterize a long time series of PM 2.5 measurements collected at a receptor site in Denver to a level of detail that has not been done before on this size data set. This has involved characterization of inorganic ions using ion chromatography, total elemental and organic carbon using thermal optical transmission, and organic molecular marker species using gas chromatography-mass spectrometry. Methods have been developed to allow for daily measurement and speciation for these compounds over a six year period. Measurement methods, novel approaches to uncertainty estimation, time series analysis, spectral and pattern analyses and source apportionment using two multivariate factor analysis models are presented. Analysis results reveal several natural and anthropogenic sources contributing to PM2.5 in Denver. The most distinguishable sources are motor vehicles and biomass combustion. This information will be used in a health effect analysis as part of a larger study called the Denver Aerosol Sources and Health (DASH) study. Such results will inform regulatory decisions and may help create a better understanding of the underlying mechanisms for the observed adverse health effects associated with PM2.5.

  2. Simultaneous speciation of arsenic, selenium, and chromium: Species stability, sample preservation, and analysis of ash and soil leachates

    USGS Publications Warehouse

    Wolf, R.E.; Morman, S.A.; Hageman, P.L.; Hoefen, T.M.; Plumlee, G.S.

    2011-01-01

    An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 ??C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present

  3. Simultaneous speciation of arsenic, selenium, and chromium: species stability, sample preservation, and analysis of ash and soil leachates.

    PubMed

    Wolf, Ruth E; Morman, Suzette A; Hageman, Philip L; Hoefen, Todd M; Plumlee, Geoffrey S

    2011-11-01

    An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 °C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present

  4. Simultaneous speciation of arsenic, selenium, and chromium: species, stability, sample preservation, and analysis of ash and soil leachates

    USGS Publications Warehouse

    Wolf, Ruth E.; Morman, Suzette A.; Hageman, Philip L.; Hoefen, Todd M.; Plumlee, Geoffrey S.

    2011-01-01

    An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10° C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present

  5. Speciation rates decline through time in individual-based models of speciation and extinction.

    PubMed

    Wang, Shaopeng; Chen, Anping; Fang, Jingyun; Pacala, Stephen W

    2013-09-01

    A well-documented pattern in the fossil record is a long-term decline in the origination rate of new taxa after diversity rebounds from a mass extinction. The mechanisms for this pattern remain elusive. In this article, we investigate the macroevolutionary predictions of an individual-based birth-death model (BDI model) where speciation and extinction rates emerge from population dynamics. We start with the simplest neutral model in which every individual has the same per capita rates of birth, death, and speciation. Although the prediction of the simplest neutral model agrees qualitatively with the fossil pattern, the predicted decline in per-species speciation rates is too fast to explain the long-term trend in fossil data. We thus consider models with variation among species in per capita rates of speciation and a suite of alternative assumptions about the heritability of speciation rate. The results show that interspecific variation in per capita speciation rate can induce differences among species in their ability to resist extinction because a low speciation rate confers a small but important demographic advantage. As a consequence, the model predicts an appropriately slow temporal decline in speciation rates, which provides a mechanistic explanation for the fossil pattern.

  6. Dynamic analysis of process reactors

    SciTech Connect

    Shadle, L.J.; Lawson, L.O.; Noel, S.D.

    1995-06-01

    The approach and methodology of conducting a dynamic analysis is presented in this poster session in order to describe how this type of analysis can be used to evaluate the operation and control of process reactors. Dynamic analysis of the PyGas{trademark} gasification process is used to illustrate the utility of this approach. PyGas{trademark} is the gasifier being developed for the Gasification Product Improvement Facility (GPIF) by Jacobs-Siffine Engineering and Riley Stoker. In the first step of the analysis, process models are used to calculate the steady-state conditions and associated sensitivities for the process. For the PyGas{trademark} gasifier, the process models are non-linear mechanistic models of the jetting fluidized-bed pyrolyzer and the fixed-bed gasifier. These process sensitivities are key input, in the form of gain parameters or transfer functions, to the dynamic engineering models.

  7. Flexible rotor dynamics analysis

    NASA Technical Reports Server (NTRS)

    Shen, F. A.

    1973-01-01

    A digital computer program was developed to analyze the general nonaxisymmetric and nonsynchronous transient and steady-state rotor dynamic performance of a bending- and shear-wise flexible rotor-bearing system under various operating conditions. The effects of rotor material mechanical hysteresis, rotor torsion flexibility, transverse effects of rotor axial and torsional loading and the anisotropic, in-phase and out-of-phase bearing stiffness and damping force and moment coefficients were included in the program to broaden its capability. An optimum solution method was found and incorporated in the computer program. Computer simulation of experimental data was made and qualitative agreements observed. The mathematical formulations, computer program verification, test data simulation, and user instruction was presented and discussed.

  8. Catalysis in a Cage: Condition-Dependent Speciation and Dynamics of Exchanged Cu Cations in SSZ-13 Zeolites.

    PubMed

    Paolucci, Christopher; Parekh, Atish A; Khurana, Ishant; Di Iorio, John R; Li, Hui; Albarracin Caballero, Jonatan D; Shih, Arthur J; Anggara, Trunojoyo; Delgass, W Nicholas; Miller, Jeffrey T; Ribeiro, Fabio H; Gounder, Rajamani; Schneider, William F

    2016-05-11

    The relationships among the macroscopic compositional parameters of a Cu-exchanged SSZ-13 zeolite catalyst, the types and numbers of Cu active sites, and activity for the selective catalytic reduction (SCR) of NOx with NH3 are established through experimental interrogation and computational analysis of materials across the catalyst composition space. Density functional theory, stochastic models, and experimental characterizations demonstrate that within the synthesis protocols applied here and across Si:Al ratios, the volumetric density of six-membered-rings (6MR) containing two Al (2Al sites) is consistent with a random Al siting in the SSZ-13 lattice subject to Löwenstein's rule. Further, exchanged Cu(II) ions first populate these 2Al sites before populating remaining unpaired, or 1Al, sites as Cu(II)OH. These sites are distinguished and enumerated ex situ through vibrational and X-ray absorption spectroscopies (XAS) and chemical titrations. In situ and operando XAS follow Cu oxidation state and coordination environment as a function of environmental conditions including low-temperature (473 K) SCR catalysis and are rationalized through first-principles thermodynamics and ab initio molecular dynamics. Experiment and theory together reveal that the Cu sites respond sensitively to exposure conditions, and in particular that Cu species are solvated and mobilized by NH3 under SCR conditions. While Cu sites are spectroscopically and chemically distinct away from these conditions, they exhibit similar turnover rates, apparent activation energies and apparent reaction orders at the SCR conditions, even on zeolite frameworks other than SSZ13.

  9. Cytogenetic and symbiont analysis of five members of the B. dorsalis complex (Diptera, Tephritidae): no evidence of chromosomal or symbiont-based speciation events

    PubMed Central

    Augustinos, Antonios A.; Drosopoulou, Elena; Gariou-Papalexiou, Aggeliki; Asimakis, Elias D.; Cáceres, Carlos; Tsiamis, George; Bourtzis, Kostas; Penelope Mavragani-Tsipidou; Zacharopoulou, Antigone

    2015-01-01

    Abstract The Bactrocera dorsalis species complex, currently comprising about 90 entities has received much attention. During the last decades, considerable effort has been devoted to delimiting the species of the complex. This information is of great importance for agriculture and world trade, since the complex harbours several pest species of major economic importance and other species that could evolve into global threats. Speciation in Diptera is usually accompanied by chromosomal rearrangements, particularly inversions that are assumed to reduce/eliminate gene flow. Other candidates currently receiving much attention regarding their possible involvement in speciation are reproductive symbionts, such as Wolbachia, Spiroplasma, Arsenophonus, Rickettsia and Cardinium. Such symbionts tend to spread quickly through natural populations and can cause a variety of phenotypes that promote pre-mating and/or post-mating isolation and, in addition, can affect the biology, physiology, ecology and evolution of their insect hosts in various ways. Considering all these aspects, we present: (a) a summary of the recently gained knowledge on the cytogenetics of five members of the Bactrocera dorsalis complex, namely Bactrocera dorsalis s.s., Bactrocera invadens, Bactrocera philippinensis, Bactrocera papayae and Bactrocera carambolae, supplemented by additional data from a Bactrocera dorsalis s.s. colony from China, as well as by a cytogenetic comparison between the dorsalis complex and the genetically close species, Bactrocera tryoni, and, (b) a reproductive symbiont screening of 18 different colonized populations of these five taxa. Our analysis did not reveal any chromosomal rearrangements that could differentiate among them. Moreover, screening for reproductive symbionts was negative for all colonies derived from different geographic origins and/or hosts. There are many different factors that can lead to speciation, and our data do not support chromosomal and/or symbiotic

  10. Cytogenetic and symbiont analysis of five members of the B. dorsalis complex (Diptera, Tephritidae): no evidence of chromosomal or symbiont-based speciation events.

    PubMed

    Augustinos, Antonios A; Drosopoulou, Elena; Gariou-Papalexiou, Aggeliki; Asimakis, Elias D; Cáceres, Carlos; Tsiamis, George; Bourtzis, Kostas; Penelope Mavragani-Tsipidou; Zacharopoulou, Antigone

    2015-01-01

    The Bactrocera dorsalis species complex, currently comprising about 90 entities has received much attention. During the last decades, considerable effort has been devoted to delimiting the species of the complex. This information is of great importance for agriculture and world trade, since the complex harbours several pest species of major economic importance and other species that could evolve into global threats. Speciation in Diptera is usually accompanied by chromosomal rearrangements, particularly inversions that are assumed to reduce/eliminate gene flow. Other candidates currently receiving much attention regarding their possible involvement in speciation are reproductive symbionts, such as Wolbachia, Spiroplasma, Arsenophonus, Rickettsia and Cardinium. Such symbionts tend to spread quickly through natural populations and can cause a variety of phenotypes that promote pre-mating and/or post-mating isolation and, in addition, can affect the biology, physiology, ecology and evolution of their insect hosts in various ways. Considering all these aspects, we present: (a) a summary of the recently gained knowledge on the cytogenetics of five members of the Bactrocera dorsalis complex, namely Bactrocera dorsalis s.s., Bactrocera invadens, Bactrocera philippinensis, Bactrocera papayae and Bactrocera carambolae, supplemented by additional data from a Bactrocera dorsalis s.s. colony from China, as well as by a cytogenetic comparison between the dorsalis complex and the genetically close species, Bactrocera tryoni, and, (b) a reproductive symbiont screening of 18 different colonized populations of these five taxa. Our analysis did not reveal any chromosomal rearrangements that could differentiate among them. Moreover, screening for reproductive symbionts was negative for all colonies derived from different geographic origins and/or hosts. There are many different factors that can lead to speciation, and our data do not support chromosomal and/or symbiotic

  11. Selective hydride generation- cryotrapping- ICP-MS for arsenic speciation analysis at picogram levels: analysis of river and sea water reference materials and human bladder epithelial cells

    PubMed Central

    Matoušek, Tomáš; Currier, Jenna M.; Trojánková, Nikola; Saunders, R. Jesse; Ishida, María C.; González-Horta, Carmen; Musil, Stanislav; Mester, Zoltán; Stýblo, Miroslav; Dědina, Jiří

    2013-01-01

    An ultra sensitive method for arsenic (As) speciation analysis based on selective hydride generation (HG) with preconcentration by cryotrapping (CT) and inductively coupled plasma- mass spectrometry (ICP-MS) detection is presented. Determination of valence of the As species is performed by selective HG without prereduction (trivalent species only) or with L-cysteine prereduction (sum of tri- and pentavalent species). Methylated species are resolved on the basis of thermal desorption of formed methyl substituted arsines after collection at −196°C. Limits of detection of 3.4, 0.04, 0.14 and 0.10 pg mL−1 (ppt) were achieved for inorganic As, mono-, di- and trimethylated species, respectively, from a 500 μL sample. Speciation analysis of river water (NRC SLRS-4 and SLRS-5) and sea water (NRC CASS-4, CASS-5 and NASS-5) reference materials certified to contain 0.4 to 1.3 ng mL−1 total As was performed. The concentrations of methylated As species in tens of pg mL−1 range obtained by HG-CT-ICP-MS systems in three laboratories were in excellent agreement and compared well with results of HG-CT-atomic absorption spectrometry and anion exchange liquid chromatography- ICP-MS; sums of detected species agreed well with the certified total As content. HG-CT-ICP-MS method was successfully used for analysis of microsamples of exfoliated bladder epithelial cells isolated from human urine. Here, samples of lysates of 25 to 550 thousand cells contained typically tens pg up to ng of iAs species and from single to hundreds pg of methylated species, well within detection power of the presented method. A significant portion of As in the cells was found in the form of the highly toxic trivalent species. PMID:24014931

  12. The arsenic contamination of rice in Guangdong Province, the most economically dynamic provinces of China: arsenic speciation and its potential health risk.

    PubMed

    Lin, Kai; Lu, Shaoyou; Wang, Jun; Yang, Yuyi

    2015-04-01

    Rice is a staple food in China, but it may contain toxic heavy metals. Hence, the concentrations of arsenic (As) species (As(III), As(V), MMA and DMA) were evaluated in 260 rice samples from 13 cities of Guangdong Province, the most economically dynamic provinces of China. The levels of sum concentrations of As species in rice samples varied from non-detect to 225.58 ng g(-1), with an average value of 57.27 ng g(-1). The mean concentrations of the major As species detected in rice samples were in the order As(III) (34.77 ng g(-1)) > As(V) (9.34 ng g(-1)) > DMA (8.33 ng g(-1)) > MMA (4.82 ng g(-1)). The rice samples of Guangdong Province were categorized as inorganic As type. Significant geographical variation of As speciation existed in rice samples of 13 cities of Guangdong Province by chi-square test (p < 0.05). The average human weekly intakes of inorganic As via rice consumption in Guangdong Province, southern China, were 1.91 µg kg(-1) body weight. Hazard quotients of total As via rice consumption of adults in 13 cities ranged from 0.06 to 0.30, indicating the As contents in rice from Guangdong Province had no potential adverse impact on human health.

  13. The speciation of iron in desert dust collected in Gran Canaria (Canary Islands): Combined chemical, magnetic and optical analysis

    NASA Astrophysics Data System (ADS)

    Lázaro, Francisco J.; Gutiérrez, Lucía; Barrón, Vidal; Gelado, María D.

    Atmospheric dust collected on filters at a coastal site in Gran Canaria has been analysed by a combination of chemical, magnetic and optical methods with the aim of determining the iron speciation. The fraction of total iron as particulate (oxyhydr)oxides, determined by the citrate-bicarbonate-dithionite method, was 0.39 ± 0.11 (mean ± s.d.); the fraction of (oxyhydr)oxide iron in ferrimagnetic form, through analysis of the saturation magnetisation, was 0.053 ± 0.038 (mean ± s.d.); and the fraction of haematite iron with respect to the iron in haematite + goethite form, by diffuse reflectance spectroscopy measurements, was 0.47 ± 0.12 (mean ± s.d.). Consistent with these findings, low temperature in-phase and out-of-phase AC susceptibility measurements reveal also the presence of paramagnetic iron, most likely in silicates with ionic substitution, and indicate that, while magnetite or haematite particles may be present in the dust, their particle size should be very small, as the typical magnetic transitions characteristic of large crystals of these oxides are practically impossible to detect. The comparison of the Fe/Al elemental ratios with typical crustal values indicates that the great majority of captured dust iron has a non-anthropogenic origin. Although no significant correlations have been found between the analysed dust properties and the dust provenance, the obtained magnetic data corresponding to the dust collected at this site may be useful, as a middle step, in future magnetic monitoring studies of the iron biogeochemical cycle.

  14. Selenium speciation analysis of Misgurnus anguillicaudatus selenoprotein by HPLC-ICP-MS and HPLC-ESI-MS/MS

    USDA-ARS?s Scientific Manuscript database

    Analytical methods for selenium (Se) speciation were developed using high performance liquid chromatography (HPLC) coupled to either inductively coupled plasma mass spectrometry (ICP-MS) or electrospray ionization tandem mass spectrometry (ESI-MS/MS). Separations of selenomethionine (Se-Met) and sel...

  15. Arsenic speciation and fucoxanthin analysis from seaweed dietary supplements using LC-MS

    USDA-ARS?s Scientific Manuscript database

    Inorganic species are considered more toxic to humans than organic arsenic and total arsenic. Analysis of total arsenic in metallic form, organic and inorganic arsenic species from seaweeds and dietary supplements using LC-ICP-MS was developed. Solvent extraction with sonication and microwave extr...

  16. Arsenic speciation in natural sulfidic geothermal waters

    NASA Astrophysics Data System (ADS)

    Keller, Nicole S.; Stefánsson, Andri; Sigfússon, Bergur

    2014-10-01

    for a first-order estimation of the dominant species, discrepancies between the model results and the field data highlight the fact that for such dynamic chemical systems the exact speciation cannot be calculated, thus on-site and preferentially in-situ analysis is of crucial importance.

  17. Metal speciation of environmental samples using SPE and SFC-AED analysis

    SciTech Connect

    Mitchell, S.C.; Burford, M.D.; Robson, M.

    1995-12-31

    Due to growing public concern over heavy metals in the environment, soil, water and air particulate samples azre now routinely screened for their metal content. Conventional metal analysis typically involves acid digestion extraction and results in the generation of large aqueous and organic solvent waste. This harsh extraction process is usually used to obtain the total metal content of the sample, the extract being analysed by atomic emission or absorption spectroscoply techniques. A more selective method of metal extraction has been investigated which uses a supercritical fluid modified with a complexing agent. The relatively mild extraction method enables both organometallic and inorganic metal species to be recovered intact. The various components from the supercritical fluid extract can be chromatographically separated using supercritical fluid chromatography (SFC) and positive identification of the metals achieved using atomic emission detection (AED). The aim of the study is to develop an analytical extraction procedure which enables a rapid, sensitive and quantitative analysis of metals in environmental samples, using just one extraction (eg SFE) and one analysis (eg SFC-AED) procedure.

  18. Simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate in welding fume alkaline extracts by HPLC-ICP-MS.

    PubMed

    Ščančar, Janez; Berlinger, Balázs; Thomassen, Yngvar; Milačič, Radmila

    2015-09-01

    A novel analytical procedure was developed for the simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate by anion-exchange high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Linear gradient elution from 100% water to 100% 0.7 M NaCl was applied for chromatographic separation of metal species. In standard aqueous solution at neutral pH molybdate, tungstate and vanadate exist in several aqueous species, while chromate is present as a single CrO4(2-) species. Consequently, only chromate can be separated from this solution in a sharp chromatographic peak. For obtaining sharp chromatographic peaks for molybdate, tungstate and vanadate, the pH of aqueous standard solutions was raised to 12. At highly alkaline conditions single CrO4(2-), MoO4(2-) and WO4(2-) are present and were eluted in sharp chromatographic peaks, while VO4(3-) species, which predominates at pH 12 was eluted in slightly broaden peak. In a mixture of aqueous standard solutions (pH 12) chromate, molybdate, tungstate and vanadate were eluted at retention times from 380 to 420 s, 320 to 370 s, 300 to 350 s and 240 to 360 s, respectively. Eluted species were simultaneously detected on-line by ICP-MS recording m/z 52, 95, 182 and 51. The developed procedure was successfully applied to the analysis of leachable concentrations of chromate, molybdate, tungstate and vanadate in alkaline extracts (2% NaOH+3% Na2CO3) of manual metal arc (MMA) welding fumes loaded on filters. Good repeatability and reproducibility of measurement (RSD±3.0%) for the investigated species were obtained in both aqueous standard solutions (pH 12) and in alkaline extracts of welding fumes. Low limits of detection (LODs) were found for chromate (0.02 ng Cr mL(-1)), molybdate (0.1 ng Mo mL(-1)), tungstate (0.1 ng W mL(-1)) and vanadate (0.2 ng V mL(-1)). The accuracy of analytical procedure for the determination of chromate was checked by analysis of

  19. Heavy metal speciation in various grain sizes of industrially contaminated street dust using multivariate statistical analysis.

    PubMed

    Yıldırım, Gülşen; Tokalıoğlu, Şerife

    2016-02-01

    A total of 36 street dust samples were collected from the streets of the Organised Industrial District in Kayseri, Turkey. This region includes a total of 818 work places in various industrial areas. The modified BCR (the European Community Bureau of Reference) sequential extraction procedure was applied to evaluate the mobility and bioavailability of trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in street dusts of the study area. The BCR was classified into three steps: water/acid soluble fraction, reducible and oxidisable fraction. The remaining residue was dissolved by using aqua regia. The concentrations of the metals in street dust samples were determined by flame atomic absorption spectrometry. Also the effect of the different grain sizes (<38µm, 38-53µm and 53-74µm) of the 36 street dust samples on the mobility of the metals was investigated using the modified BCR procedure. The mobility sequence based on the sum of the first three phases (for <74µm grain size) was: Cd (71.3)>Cu (48.9)>Pb (42.8)=Cr (42.1)>Ni (41.4)>Zn (40.9)>Co (36.6)=Mn (36.3)>Fe (3.1). No significant difference was observed among metal partitioning for the three particle sizes. Correlation, principal component and cluster analysis were applied to identify probable natural and anthropogenic sources in the region. The principal component analysis results showed that this industrial district was influenced by traffic, industrial activities, air-borne emissions and natural sources. The accuracy of the results was checked by analysis of both the BCR-701 certified reference material and by recovery studies in street dust samples.

  20. Tritium speciation in nuclear reactor bioshield concrete and its impact on accurate analysis.

    PubMed

    Kim, Dae Ji; E Warwick, Phillip; Croudace, Ian W

    2008-07-15

    Tritium ((3)H) is produced in nuclear reactors via several neutron-induced reactions [(2)H(n, gamma)(3)H, (6)Li(n, alpha)(3)H, (10)B(n, 2alpha)(3)H, (14)N(n, (3)H)(12)C, and ternary fission (fission yield <0.01%)]. Typically, (3)H is present as tritiated water (HTO) and can become adsorbed into structural concrete from the surface inward where it will be held in a weakly bound form. However, a systematic analysis of a sequence of subsamples taken from a reactor bioshield using combustion and liquid scintillation analysis has identified two forms of (3)H, one weakly bound and one strongly bound. The strongly bound tritium, which originates from neutron capture on trace lithium ((6)Li) within mineral phases, requires temperatures in excess of 350 degrees C to achieve quantitative recovery. The weakly bound form of tritium can be liberated at significantly lower temperatures (100 degrees C) as HTO and is associated with dehydration of hydrous mineral components. Without an appreciation that two forms of tritium can exist in reactor bioshields, the (3)H content of samples may be severely underestimated using conventional analytical approaches. These findings exemplify the need to develop robust radioactive waste characterization procedures in support of nuclear decommissioning programs.

  1. SPECIATE 4.2: speciation Database Development Documentation

    EPA Science Inventory

    SPECIATE is the U.S. Environmental Protection Agency's (EPA) repository of volatile organic gas and particulate matter (PM) speciation profiles of air pollution sources. Among the many uses of speciation data, these source profiles are used to: (1) create speciated emissions inve...

  2. Minimal effects of latitude on present-day speciation rates in New World birds

    PubMed Central

    Rabosky, Daniel L.; Title, Pascal O.; Huang, Huateng

    2015-01-01

    The tropics contain far greater numbers of species than temperate regions, suggesting that rates of species formation might differ systematically between tropical and non-tropical areas. We tested this hypothesis by reconstructing the history of speciation in New World (NW) land birds using BAMM, a Bayesian framework for modelling complex evolutionary dynamics on phylogenetic trees. We estimated marginal distributions of present-day speciation rates for each of 2571 species of birds. The present-day rate of speciation varies approximately 30-fold across NW birds, but there is no difference in the rate distributions for tropical and temperate taxa. Using macroevolutionary cohort analysis, we demonstrate that clades with high tropical membership do not produce species more rapidly than temperate clades. For nearly any value of present-day speciation rate, there are far more species in the tropics than the temperate zone. Any effects of latitude on speciation rate are marginal in comparison to the dramatic variation in rates among clades. PMID:26019156

  3. Minimal effects of latitude on present-day speciation rates in New World birds.

    PubMed

    Rabosky, Daniel L; Title, Pascal O; Huang, Huateng

    2015-06-22

    The tropics contain far greater numbers of species than temperate regions, suggesting that rates of species formation might differ systematically between tropical and non-tropical areas. We tested this hypothesis by reconstructing the history of speciation in New World (NW) land birds using BAMM, a Bayesian framework for modelling complex evolutionary dynamics on phylogenetic trees. We estimated marginal distributions of present-day speciation rates for each of 2571 species of birds. The present-day rate of speciation varies approximately 30-fold across NW birds, but there is no difference in the rate distributions for tropical and temperate taxa. Using macroevolutionary cohort analysis, we demonstrate that clades with high tropical membership do not produce species more rapidly than temperate clades. For nearly any value of present-day speciation rate, there are far more species in the tropics than the temperate zone. Any effects of latitude on speciation rate are marginal in comparison to the dramatic variation in rates among clades. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  4. Analysis of complete mitochondrial genome sequences increases phylogenetic resolution of bears (Ursidae), a mammalian family that experienced rapid speciation.

    PubMed

    Yu, Li; Li, Yi-Wei; Ryder, Oliver A; Zhang, Ya-Ping

    2007-10-24

    Despite the small number of ursid species, bear phylogeny has long been a focus of study due to their conservation value, as all bear genera have been classified as endangered at either the species or subspecies level. The Ursidae family represents a typical example of rapid evolutionary radiation. Previous analyses with a single mitochondrial (mt) gene or a small number of mt genes either provide weak support or a large unresolved polytomy for ursids. We revisit the contentious relationships within Ursidae by analyzing complete mt genome sequences and evaluating the performance of both entire mt genomes and constituent mtDNA genes in recovering a phylogeny of extremely recent speciation events. This mitochondrial genome-based phylogeny provides strong evidence that the spectacled bear diverged first, while within the genus Ursus, the sloth bear is the sister taxon of all the other five ursines. The latter group is divided into the brown bear/polar bear and the two black bears/sun bear assemblages. These findings resolve the previous conflicts between trees using partial mt genes. The ability of different categories of mt protein coding genes to recover the correct phylogeny is concordant with previous analyses for taxa with deep divergence times. This study provides a robust Ursidae phylogenetic framework for future validation by additional independent evidence, and also has significant implications for assisting in the resolution of other similarly difficult phylogenetic investigations. Identification of base composition bias and utilization of the combined data of whole mitochondrial genome sequences has allowed recovery of a strongly supported phylogeny that is upheld when using multiple alternative outgroups for the Ursidae, a mammalian family that underwent a rapid radiation since the mid- to late Pliocene. It remains to be seen if the reliability of mt genome analysis will hold up in studies of other difficult phylogenetic issues. Although the whole

  5. Analysis of complete mitochondrial genome sequences increases phylogenetic resolution of bears (Ursidae), a mammalian family that experienced rapid speciation

    PubMed Central

    Yu, Li; Li, Yi-Wei; Ryder, Oliver A; Zhang, Ya-Ping

    2007-01-01

    Background Despite the small number of ursid species, bear phylogeny has long been a focus of study due to their conservation value, as all bear genera have been classified as endangered at either the species or subspecies level. The Ursidae family represents a typical example of rapid evolutionary radiation. Previous analyses with a single mitochondrial (mt) gene or a small number of mt genes either provide weak support or a large unresolved polytomy for ursids. We revisit the contentious relationships within Ursidae by analyzing complete mt genome sequences and evaluating the performance of both entire mt genomes and constituent mtDNA genes in recovering a phylogeny of extremely recent speciation events. Results This mitochondrial genome-based phylogeny provides strong evidence that the spectacled bear diverged first, while within the genus Ursus, the sloth bear is the sister taxon of all the other five ursines. The latter group is divided into the brown bear/polar bear and the two black bears/sun bear assemblages. These findings resolve the previous conflicts between trees using partial mt genes. The ability of different categories of mt protein coding genes to recover the correct phylogeny is concordant with previous analyses for taxa with deep divergence times. This study provides a robust Ursidae phylogenetic framework for future validation by additional independent evidence, and also has significant implications for assisting in the resolution of other similarly difficult phylogenetic investigations. Conclusion Identification of base composition bias and utilization of the combined data of whole mitochondrial genome sequences has allowed recovery of a strongly supported phylogeny that is upheld when using multiple alternative outgroups for the Ursidae, a mammalian family that underwent a rapid radiation since the mid- to late Pliocene. It remains to be seen if the reliability of mt genome analysis will hold up in studies of other difficult phylogenetic

  6. Stabilization of mercury over Mn-based oxides: Speciation and reactivity by temperature programmed desorption analysis.

    PubMed

    Xu, Haomiao; Ma, Yongpeng; Huang, Wenjun; Mei, Jian; Zhao, Songjian; Qu, Zan; Yan, Naiqiang

    2017-01-05

    Mercury temperature-programmed desorption (Hg-TPD) method was employed to clarify mercury species over Mn-based oxides. The elemental mercury (Hg(0)) removal mechanism over MnOx was ascribed to chemical-adsorption. HgO was the primary mercury chemical compound adsorbed on the surface of MnOx. Rare earth element (Ce), main group element (Sn) and transition metal elements (Zr and Fe) were chosen for the modification of MnOx. Hg-TPD results indicated that the binding strength of mercury on these binary oxides followed the order of Sn-MnOxanalysis. SO2 had a poison effect on Hg(0) removal, and the weak bond of mercury can be easily destroyed by SO2. NO was favorable for Hg(0) removal, and the bond strength of mercury was enhanced.

  7. Nonlinear analysis of dynamic signature

    NASA Astrophysics Data System (ADS)

    Rashidi, S.; Fallah, A.; Towhidkhah, F.

    2013-12-01

    Signature is a long trained motor skill resulting in well combination of segments like strokes and loops. It is a physical manifestation of complex motor processes. The problem, generally stated, is that how relative simplicity in behavior emerges from considerable complexity of perception-action system that produces behavior within an infinitely variable biomechanical and environmental context. To solve this problem, we present evidences which indicate that motor control dynamic in signing process is a chaotic process. This chaotic dynamic may explain a richer array of time series behavior in motor skill of signature. Nonlinear analysis is a powerful approach and suitable tool which seeks for characterizing dynamical systems through concepts such as fractal dimension and Lyapunov exponent. As a result, they can be analyzed in both horizontal and vertical for time series of position and velocity. We observed from the results that noninteger values for the correlation dimension indicates low dimensional deterministic dynamics. This result could be confirmed by using surrogate data tests. We have also used time series to calculate the largest Lyapunov exponent and obtain a positive value. These results constitute significant evidence that signature data are outcome of chaos in a nonlinear dynamical system of motor control.

  8. Simultaneous determination and speciation analysis of arsenic and chromium in iron supplements used for iron-deficiency anemia treatment by HPLC-ICP-MS.

    PubMed

    Araujo-Barbosa, Uenderson; Peña-Vazquez, Elena; Barciela-Alonso, Maria Carmen; Costa Ferreira, Sergio Luis; Pinto Dos Santos, Ana Maria; Bermejo-Barrera, Pilar

    2017-08-01

    This work proposes the use of high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for simultaneous speciation of arsenic and chromium in iron supplements used for the treatment of anemia. The sample preparation procedure recommended for the total determination of arsenic and chromium was established using acid digestion in a microwave assisted oven. For speciation analysis, however, the microwave-assisted extraction procedure involved the use of water as extraction solvent at 90°C for 30min. The chromatographic separation was performed using a mobile phase containing 1.0mM tetrabutylammonium hydroxide (TBAH), 0.7mM ethylenediaminetetraacetic acid (EDTA) and 5% methanol at pH 7.2. Helium was used in the collision cell for elimination of the interferences. Under optimized conditions, the separation and detection of the As(III), As(V), Cr(III) and Cr(VI) species can be performed in 5min, permitting their quantification with the external calibration technique with standards prepared in the mobile phase. The limits of quantification obtained were 0.008, 0.010, 0.5 and 0.14µgg(-1), for As(III), As(V), Cr(III) and Cr(VI), respectively. The accuracy of the method was evaluated and confirmed by addition/recovery tests. The recoveries obtained varied from 81% to 110%. The proposed method was applied to the speciation analysis of arsenic and chromium in commercially available iron supplements acquired in several cities in Brazil and Spain. The content of the species ranged from 0.01 to 1.3µgg(-1) for arsenic, and from 0.4 to 61.2µgg(-1) for chromium. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Use of ion-pairing reagent for improving iodine speciation analysis in seaweed by pressure-driven capillary electrophoresis and ultraviolet detection.

    PubMed

    Sun, Jiannan; Wang, Dan; Cheng, Heyong; Liu, Jinhua; Wang, Yuanchao; Xu, Zigang

    2015-01-30

    This study achieved resolution improvement for iodine speciation in the presence of an ion-pairing reagent by a pressure-driven capillary electrophoresis (CE) system. Addition of 0.01mM tetrabutyl ammonium hydroxide (TBAH) as the ion-pairing reagent into the electrophoretic buffer resulted in the complete separation of four iodine species (I(-), IO3(-), mono-iodothyrosine-MIT and di-iodothyrosine-DIT), because of the electrostatic interaction between TBAH and the negatively charged analytes. A +16kV separation voltage was applied along the separation capillary (50μm i.d., 80cm total and 60cm effective) with the inlet grounded. The detection wavelength was fixed at 210nm, and the pressure-driven flow rate was set at 0.12mLmin(-1) with an injected volume of 2μL. The optimal electrolyte consisted of 2mM borate, 2mM TBAH and 80% methanol with pH adjusted to 8.5. Baseline separation of iodine species was achieved within 7min. The detection limits for I(-), IO3(-), MIT and DIT were 0.052, 0.040, 0.032 and 0.025mgL(-1), respectively. The relative standard deviations of peak heights and areas were all below 3% for 5mgL(-1) and 5% for 1mgL(-1). Application of the proposed method was demonstrated by speciation analysis of iodine in two seaweed samples. The developed method offered satisfactory recoveries in the 91-99% range and good precisions (<5%). Good agreement between the determined values by the proposed CE method and the HPLC-ICP-MS method was also obtained. All results proved its great potential in routine analysis of iodine speciation in environmental, food and biological samples.

  10. Speciation Analysis of Arsenic by Selective Hydride Generation-Cryotrapping-Atomic Fluorescence Spectrometry with Flame-in-Gas-Shield Atomizer: Achieving Extremely Low Detection Limits with Inexpensive Instrumentation

    PubMed Central

    2015-01-01

    This work describes the method of a selective hydride generation-cryotrapping (HG-CT) coupled to an extremely sensitive but simple in-house assembled and designed atomic fluorescence spectrometry (AFS) instrument for determination of toxicologically important As species. Here, an advanced flame-in-gas-shield atomizer (FIGS) was interfaced to HG-CT and its performance was compared to a standard miniature diffusion flame (MDF) atomizer. A significant improvement both in sensitivity and baseline noise was found that was reflected in improved (4 times) limits of detection (LODs). The yielded LODs with the FIGS atomizer were 0.44, 0.74, 0.15, 0.17 and 0.67 ng L–1 for arsenite, total inorganic, mono-, dimethylated As and trimethylarsine oxide, respectively. Moreover, the sensitivities with FIGS and MDF were equal for all As species, allowing for the possibility of single species standardization with arsenate standard for accurate quantification of all other As species. The accuracy of HG-CT-AFS with FIGS was verified by speciation analysis in two samples of bottled drinking water and certified reference materials, NRC CASS-5 (nearshore seawater) and SLRS-5 (river water) that contain traces of methylated As species. As speciation was in agreement with results previously reported and sums of all quantified species corresponded with the certified total As. The feasibility of HG-CT-AFS with FIGS was also demonstrated by the speciation analysis in microsamples of exfoliated bladder epithelial cells isolated from human urine. The results for the sums of trivalent and pentavalent As species corresponded well with the reference results obtained by HG-CT-ICPMS (inductively coupled plasma mass spectrometry). PMID:25300934

  11. Appropriate sampling strategy and analytical methodology to address contamination by industry. Part 2: Geochemistry and speciation analysis

    NASA Astrophysics Data System (ADS)

    Shtiza, Aurela; Swennen, Rudy

    2011-03-01

    The degree of contamination in soils, sediments and dusts can be assessed based on knowledge of a variety of factors, such as industrialization, type of contaminants, deposition conditions, contamination-control techniques, along with the characteristics of the recipient environmental compartments, which include pathways for contamination transport, depth of infiltration, and degree of groundwater contamination. The impact of contaminants also depends on the quantity, mobility and speciation of contaminants/wastes as well as on the sensitivity of the recipient compartments. With sufficient knowledge of these factors, a number of conclusions can be drawn concerning the status of contamination in industrialized areas. This literature review aims to scrutinize some of the methods used to analyse the occurrence, speciation, mobility, bioavailability and likely the toxic effects of contaminants in the environment.

  12. Speciation and long- and short-term molecular-level dynamics of soil organic sulfur studied by X-ray absorption near-edge structure spectroscopy.

    PubMed

    Solomon, Dawit; Lehmann, Johannes; de Zarruk, Katrin Knoth; Dathe, Julia; Kinyangi, James; Liang, Biqing; Machado, Stephen

    2011-01-01

    We investigated speciation, oxidative state changes, and long- and short-term molecular-level dynamics of organic S after 365 d of aerobic incubation with and without the addition of sugarcane residue using XANES spectroscopy. Soil samples were collected from the upper 15 cm of undisturbed grasslands since 1880, from undisturbed grasslands since 1931, and from cultivated fields since 1880 in the western United States. We found three distinct groups of organosulfur compounds in these grassland-derived soils: (i) strongly reduced (S to S) organic S that encompasses thiols, monosulfides, disulfides, polysulfides, and thiophenes; (ii) organic S in intermediate oxidation (S to S) states, which include sulfoxides and sulfonates; and (iii) strongly oxidized (S) organic S, which comprises ester-SO-S. The first two groups represent S directly linked to C and accounted for 80% of the total organic S detected by XANES from the undisturbed soils. Aerobic incubation without the addition of sugarcane residue led to a 21% decline in organanosulfur compounds directly linked to C and to up to an 82% increase inorganic S directly bonded to O. Among the C-bonded S compounds, low-valence thiols, sulfides, thiophenic S, and intermediate-valence sulfoxide S seem to be highly susceptible to microbial attack and may represent the most reactive components of organic S pool in these grassland soils. Sulfonate S exhibited a much lower short-term reactivity. The incorporation of sugarcane residue resulted in an increase in organosulfur compounds directly bonded to C at the early stage of incubation. However, similar to soils incubated without residue addition, the proportion of organic S directly linked to C continued to decline with increasing duration of aerobic incubation, whereas the proportion of organic S directly bonded to O showed a steady rise. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

  13. Speciation and Long- and Short-term Molecular-level Dynamics of Soil Organic Sulfur Studied by X-ray Absorption Near-Edge Structure Spectroscopy

    SciTech Connect

    D Solomon; J Lehmann; K Knoth de Zarruk; J Dathe; J Kinyangi; B Liang; S Machado

    2011-12-31

    We investigated speciation, oxidative state changes, and long- and short-term molecular-level dynamics of organic S after 365 d of aerobic incubation with and without the addition of sugarcane residue using XANES spectroscopy. Soil samples were collected from the upper 15 cm of undisturbed grasslands since 1880, from undisturbed grasslands since 1931, and from cultivated fields since 1880 in the western United States. We found three distinct groups of organosulfur compounds in these grassland-derived soils: (i) strongly reduced (S{sup 0} to S{sup 1+}) organic S that encompasses thiols, monosulfides, disulfides, polysulfides, and thiophenes; (ii) organic S in intermediate oxidation (S{sup 2+} to S{sup 5+}) states, which include sulfoxides and sulfonates; and (iii) strongly oxidized (S{sup 6+}) organic S, which comprises ester-SO{sub 4}-S. The first two groups represent S directly linked to C and accounted for 80% of the total organic S detected by XANES from the undisturbed soils. Aerobic incubation without the addition of sugarcane residue led to a 21% decline in organanosulfur compounds directly linked to C and to up to an 82% increase inorganic S directly bonded to O. Among the C-bonded S compounds, low-valence thiols, sulfides, thiophenic S, and intermediate-valence sulfoxide S seem to be highly susceptible to microbial attack and may represent the most reactive components of organic S pool in these grassland soils. Sulfonate S exhibited a much lower short-term reactivity. The incorporation of sugarcane residue resulted in an increase in organosulfur compounds directly bonded to C at the early stage of incubation. However, similar to soils incubated without residue addition, the proportion of organic S directly linked to C continued to decline with increasing duration of aerobic incubation, whereas the proportion of organic S directly bonded to O showed a steady rise.

  14. Towards silicon speciation in light petroleum products using gas chromatography coupled to inductively coupled plasma mass spectrometry equipped with a dynamic reaction cell

    NASA Astrophysics Data System (ADS)

    Chainet, Fabien; Lienemann, Charles-Philippe; Ponthus, Jeremie; Pécheyran, Christophe; Castro, Joaudimir; Tessier, Emmanuel; Donard, Olivier François Xavier

    2014-07-01

    Silicon speciation has recently gained interest in the oil and gas industry due to the significant poisoning problems caused by silicon on hydrotreatment catalysts. The poisoning effect clearly depends on the structure of the silicon species which must be determined and quantified. The hyphenation of gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) allows a specific detection to determine the retention times of all silicon species. The aim of this work is to determine the retention indices of unknown silicon species to allow their characterization by a multi-technical approach in order to access to their chemical structure. The optimization of the dynamic reaction cell (DRC) of the ICP-MS using hydrogen as reactant gas successfully demonstrated the resolution of the interferences (14N14N+ and 12C16O+) initially present on 28Si. The linearity was excellent for silicon compounds and instrumental detection limits ranged from 20 to 140 μg of Si/kg depending on the response of the silicon compounds. A continuous release of silicon in the torch was observed most likely due to the use of a torch and an injector which was made of quartz. A non-universal response for silicon was observed and it was clearly necessary to use response coefficients to quantify silicon compounds. Known silicon compounds such as cyclic siloxanes (D3-D16) coming from PDMS degradation were confirmed. Furthermore, more than 10 new silicon species never characterized before in petroleum products were highlighted in polydimethylsiloxane (PDMS) degradation samples produced under thermal cracking of hydrocarbons. These silicon species mainly consisted of linear and cyclic structures containing reactive functions such as ethoxy, peroxide and hydroxy groups which can be able to react with the alumina surface and hence, poison the catalyst. This characterization will further allow the development of innovative solutions such as trapping silicon compounds or

  15. Variable Dynamic Testbed Vehicle: Dynamics Analysis

    NASA Technical Reports Server (NTRS)

    Lee, A. Y.; Le, N. T.; Marriott, A. T.

    1997-01-01

    The Variable Dynamic Testbed Vehicle (VDTV) concept has been proposed as a tool to evaluate collision avoidance systems and to perform driving-related human factors research. The goal of this study is to analytically investigate to what extent a VDTV with adjustable front and rear anti-roll bar stiffnesses, programmable damping rates, and four-wheel-steering can emulate the lateral dynamics of a broad range of passenger vehicles.

  16. Variable Dynamic Testbed Vehicle: Dynamics Analysis

    NASA Technical Reports Server (NTRS)

    Lee, A. Y.; Le, N. T.; Marriott, A. T.

    1997-01-01

    The Variable Dynamic Testbed Vehicle (VDTV) concept has been proposed as a tool to evaluate collision avoidance systems and to perform driving-related human factors research. The goal of this study is to analytically investigate to what extent a VDTV with adjustable front and rear anti-roll bar stiffnesses, programmable damping rates, and four-wheel-steering can emulate the lateral dynamics of a broad range of passenger vehicles.

  17. A Review on Recent Applications of High-Performance Liquid Chromatography in Metal Determination and Speciation Analysis.

    PubMed

    Rekhi, Heena; Rani, Susheela; Sharma, Neha; Malik, Ashok Kumar

    2017-06-23

    High-performance liquid chromatography (HPLC) has several advantages over the conventional methods due to their operational simplicity. It is a vital tool to determine metal ions having same mass but different electronic configuration, to separate complex mixtures and to resolve ions that may be indistinguishable by mass spectrometry alone. Metal ions play vital role in many biological processes and involved in setting up of many diseases. Therefore, the development of simple methods for the detection and quantification of metals in real samples might serve as diagnostic tools for various diseases. This review article focuses on the recent main feature of this technique, i.e. speciation of metal ions and their applications to series of problem of metal ion chemistry in different environmental matrixes. Speciation of metals is of increasing interest and has a great importance because of bioavailability, environmental mobility, toxicity and potential risk of metals. With the capability of partitioning the complex species of different metal ions, HPLC is an efficient technique for this task. This review summarizes recent advances in the development of HPLC to the fundamental understanding of metal ion chemistry in the environment and discusses all the issues that still need a lot of consideration. It has been classified into different sections depending on the role of HPLC in separation used and metal speciation; furthermore, the underlying sample preconcentration techniques and detection systems involved for the determination of metal ions and their applications were discussed.

  18. Nickel (II) Preconcentration and Speciation Analysis During Transport from Aqueous Solutions Using a Hollow-fiber Permeation Liquid Membrane (HFPLM) Device.

    PubMed

    Bautista-Flores, Ana Nelly; De San Miguel, Eduardo Rodríguez; Gyves, Josefina de; Jönsson, Jan Åke

    2011-08-18

    Nickel (II) preconcentration and speciation analysis using a hollow fiber supported liquid membrane (HFSLM) device was studied. A counterflow of protons coupled to complexation with formate provided the driving force of the process, while Kelex 100 was employed as carrier. The influence of variables related to module configuration (acceptor pH and carrier concentration) and to the sample properties (donor pH) on the preconcentration factor, E, was simultaneously studied and optimized using a 3 factor Doehlert matrix response surface methodology. The effect of metal concentration was studied as well. Preconcentration factors as high as 4240 were observed  depending on the values of the different variables. The effects of the presence of inorganic anions (NO2-, SO42-, Cl-, NO3-, CO32-, CN-) and dissolved organic matter (DOM) in the form of humic acids were additionally considered in order to carry out a speciation analysis study. Nickel preconcentration was observed to be independent of both effects, except when cyanide was present in the donor phase. A characterization of the transport regime was performed through the analysis of the dependence of E on the temperature. E increases with the increase in temperature according to the equation E(K) = -8617.3 + 30.5T with an activation energy of 56.7 kJ mol-1 suggesting a kinetic-controlled regime. Sample depletion ranged from 12 to 1.2% depending on the volume of the donor phase (100 to 1000 mL, respectively).

  19. Speciation of challenging elements in food by atomic spectrometry.

    PubMed

    Ruzik, Lena

    2012-05-15

    The review addresses trends in speciation analysis of challenging - rather rarely examined despite their importance for human health - elements in foodstuffs with special attention prior to sample preparation. Elements of interest are cobalt, iodine, manganese, iron, zinc, copper and molybdenum belong to the group of elements still appealed for searching their speciation despite extremely small contents in foodstuffs. Advantages and weaknesses of recommended procedures are overviewed and discussed, highlighting state-of-the-art speciation methodologies developed so far in the field.

  20. SPECIATE 4.3: Addendum to SPECIATE 4.2--Speciation database development documentation

    EPA Science Inventory

    SPECIATE is the U.S. Environmental Protection Agency's (EPA) repository of volatile organic gas and particulate matter (PM) speciation profiles of air pollution sources. Among the many uses of speciation data, these source profiles are used to: (1) create speciated emissions inve...

  1. Speciation analysis, bioavailability and risk assessment of trace metals in herbal decoctions using a combined technique of in Vitro digestion and biomembrane filtration as sample pretreatment method.

    PubMed

    Li, Shun-Xing; Lin, Lu-xiu; Lin, Jing; Zheng, Feng-Ying; Wang, Qing-Xiang; Weng, Wen

    2010-01-01

    Sample preparation is the first crucial step in the speciation analysis, bioavailability and risk assessment of trace metals in plant samples such as herb and vegetables. Two bionic technologies titled 'in vitro digestion' and 'extraction with biomembrane' were developed for pre-treatment of herbal decoction. The decoctions of Aconiteum carmichaeli and Paeonia lactiflora were digested at body temperature, at the acidity of the stomach or intestine and with inorganic and organic materials (digestive enzymes were included for whole-bionic and excluded for semi-bionic) found in the stomach or intestine. Being similar to the biomembrane between the gastrointestinal tract and blood vessels, monolayer liposome was used as a biomembrane model. Affinity-monolayer liposome metals and water-soluble metals were used for speciation analysis and bioavailability assessment of copper and zinc in herbal decoction. In the decoction of Aconiteum carmichaeli and Paeonia lactiflora, Zn was mainly absorbed in the intestine and Cu was mainly absorbed by both stomach and intestine. The safe dosage for males and females is below 257.1 g/day Aconiteum carmichaeli and 529.4 g/day Paeonia lactiflora. Copyright © 2010 John Wiley & Sons, Ltd.

  2. Speciation and Structural Properties of Hydrothermal Solutions of Sodium and Potassium Sulfate Studied by Molecular Dynamics Simulations.

    PubMed

    Reimer, Joachim; Vogel, Frédéric; Steele-MacInnis, Matthew

    2016-05-18

    Aqueous solutions of salts at elevated pressures and temperatures play a key role in geochemical processes and in applications of supercritical water in waste and biomass treatment, for which salt management is crucial for performance. A major question in predicting salt behavior in such processes is how different salts affect the phase equilibria. Herein, molecular dynamics (MD) simulations are used to investigate molecular-scale structures of solutions of sodium and/or potassium sulfate, which show contrasting macroscopic behavior. Solutions of Na-SO4 exhibit a tendency towards forming large ionic clusters with increasing temperature, whereas solutions of K-SO4 show significantly less clustering under equivalent conditions. In mixed systems (Nax K2-x SO4 ), cluster formation is dramatically reduced with decreasing Na/(K+Na) ratio; this indicates a structure-breaking role of K. MD results allow these phenomena to be related to the characteristics of electrostatic interactions between K(+) and SO4 (2-) , compared with the analogous Na(+) -SO4 (2-) interactions. The results suggest a mechanism underlying the experimentally observed increasing solubility in ternary mixtures of solutions of Na-K-SO4 . Specifically, the propensity of sodium to associate with sulfate, versus that of potassium to break up the sodium-sulfate clusters, may affect the contrasting behavior of these salts. Thus, mutual salting-in in ternary hydrothermal solutions of Na-K-SO4 reflects the opposing, but complementary, natures of Na-SO4 versus K-SO4 interactions. The results also provide clues towards the reported liquid immiscibility in this ternary system.

  3. Geochemical speciation and dynamic of copper in tropical semi-arid soils exposed to metal-bearing mine wastes.

    PubMed

    Perlatti, Fabio; Otero, Xosé Luis; Macias, Felipe; Ferreira, Tiago Osório

    2014-12-01

    The potentially hazardous effects of rock wastes disposed at open pit in three different areas (Pr: Ore processing; Wr: Waste rock and Bd: Border) of an abandoned copper mine were evaluated in this study, with emphasis on acid drainage generation, metal contamination and copper geochemical dynamics in soils. Samples of waste rock were analyzed by Energy dispersive X-ray fluorescence (XRF), scanning electron microscopy with microanalysis (SEM-EDS) and X-ray diffraction (XRD). Soil samples were analyzed to determine the total metal contents (XRF), mineralogy (XRD), pH (H2O and H2O2), organic and inorganic carbon, % of total N, S and P, particle size, and a sequential extraction procedure was used to identify the different copper fractions. As a result of the prevalence of carbonates over sulphides in the wastes, the soil pH remained close to neutral, with absence of acid mine drainage. The geochemical interaction between these mineral phases seems to be the main mechanism to release Cu(2)(+) ions. Total Cu in soils from the Pr area reached 11,180mg.kg(-1), while in Wr and Bd areas the values reached, on average, 4683 and 1086mg.kg(-1), respectively, indicating a very high level of soil contamination. In the Pr and Wr, the Cu was mainly associated with carbonates and amorphous iron oxides. In the Bd areas, the presence of vegetation has influenced the geochemical behavior of copper by increasing the dissolution of carbonates, affecting the buffer capacity of soils against sulphide oxidation, reducing the pH levels and enhancing the proportion of exchangeable and organic bound Cu. The present findings show that the use of plants or organic amendments in mine sites with high concentration of Cu carbonate-containing wastes should be viewed with caution, as the practice may enhance the mobilization of copper to the environment due to an increase in the rate of carbonates dissolution. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. What Is Speciation?

    PubMed Central

    Shapiro, B. Jesse; Leducq, Jean-Baptiste; Mallet, James

    2016-01-01

    Concepts and definitions of species have been debated by generations of biologists and remain controversial. Microbes pose a particular challenge because of their genetic diversity, asexual reproduction, and often promiscuous horizontal gene transfer (HGT). However, microbes also present an opportunity to study and understand speciation because of their rapid evolution, both in nature and in the lab, and small, easily sequenced genomes. Here, we review how microbial population genomics has enabled us to catch speciation “in the act” and how the results have challenged and enriched our concepts of species, with implications for all domains of life. We describe how recombination (including HGT and introgression) has shaped the genomes of nascent microbial, animal, and plant species and argue for a prominent role of natural selection in initiating and maintaining speciation. We ask how universal is the process of speciation across the tree of life, and what lessons can be drawn from microbes? Comparative genomics showing the extent of HGT in natural populations certainly jeopardizes the relevance of vertical descent (i.e., the species tree) in speciation. Nevertheless, we conclude that species do indeed exist as clusters of genetic and ecological similarity and that speciation is driven primarily by natural selection, regardless of the balance between horizontal and vertical descent. PMID:27030977

  5. What Is Speciation?

    PubMed

    Shapiro, B Jesse; Leducq, Jean-Baptiste; Mallet, James

    2016-03-01

    Concepts and definitions of species have been debated by generations of biologists and remain controversial. Microbes pose a particular challenge because of their genetic diversity, asexual reproduction, and often promiscuous horizontal gene transfer (HGT). However, microbes also present an opportunity to study and understand speciation because of their rapid evolution, both in nature and in the lab, and small, easily sequenced genomes. Here, we review how microbial population genomics has enabled us to catch speciation "in the act" and how the results have challenged and enriched our concepts of species, with implications for all domains of life. We describe how recombination (including HGT and introgression) has shaped the genomes of nascent microbial, animal, and plant species and argue for a prominent role of natural selection in initiating and maintaining speciation. We ask how universal is the process of speciation across the tree of life, and what lessons can be drawn from microbes? Comparative genomics showing the extent of HGT in natural populations certainly jeopardizes the relevance of vertical descent (i.e., the species tree) in speciation. Nevertheless, we conclude that species do indeed exist as clusters of genetic and ecological similarity and that speciation is driven primarily by natural selection, regardless of the balance between horizontal and vertical descent.

  6. Speciation analysis of inorganic arsenic in coal samples by microwave-assisted extraction and high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry.

    PubMed

    Sun, Mei; Liu, Guijian; Wu, Qianghua; Liu, Wenqi

    2013-03-15

    A new method was developed for the speciation analysis of inorganic arsenic in coal samples by high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry after microwave-assisted extraction. Effective extract of As(III) and As(V) in coal sample was achieved by 1.0 mol L(-1)H₃PO₄ and 0.1 mol L(-1)ascorbic acid. Under the optimized conditions, the limits of detection (LOD) were 0.01 μg L(-1) and 0.02 μg L(-1), the relative standard deviations (RSD) were 2.4% and 3.3% (c=10.0 μg L(-1), n=7), recoveries were 102.5% and 96.5% for As(III) and As(V). The proposed method was successfully applied for the determination of speciation of inorganic arsenic in coal samples and GBW11117 coal standard reference material with complex matrix. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry.

    PubMed

    López-García, Ignacio; Briceño, Marisol; Hernández-Córdoba, Manuel

    2011-08-05

    A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L(-1) tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V)+MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g(-1) expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Monte Carlo simulations of parapatric speciation

    NASA Astrophysics Data System (ADS)

    Schwämmle, V.; Sousa, A. O.; de Oliveira, S. M.

    2006-06-01

    Parapatric speciation is studied using an individual-based model with sexual reproduction. We combine the theory of mutation accumulation for biological ageing with an environmental selection pressure that varies according to the individuals geographical positions and phenotypic traits. Fluctuations and genetic diversity of large populations are crucial ingredients to model the features of evolutionary branching and are intrinsic properties of the model. Its implementation on a spatial lattice gives interesting insights into the population dynamics of speciation on a geographical landscape and the disruptive selection that leads to the divergence of phenotypes. Our results suggest that assortative mating is not an obligatory ingredient to obtain speciation in large populations at low gene flow.

  9. Nonlinear analysis of drought dynamics

    NASA Astrophysics Data System (ADS)

    Ma, M.

    2015-12-01

    Drought is an extreme natural hazard and becomes a severe problem in the world. It arises as a result of interactions between climate input and human activity, displaying the nonlinearity and complexity. Nonlinear time series analyses open a way to study the underlying dynamic characteristics of drought, and then provide the forward knowledge to understanding the physical mechanism of drought event. The rationale behind this idea is that information about the representation of nonlinear properties could be used as an additional quality indicator. To that end, the correlation dimension method, a powerful nonlinear time series analysis method based on the chaos theory, has been suggested to assess the intrinsic dimensionality or degree of freedom of time series according to Takens (1981). It can provide an assessment of the dominant processes that is required to map the observed dynamics. In this study, daily discharge and hourly groundwater level data of 63 catchments in Germany and China were investigated with correlation dimension method. The results indicated that the correlation dimension values of studied discharge exhibited none clear spatial patterns, but showed significant correlations with the spatial heterogeneity within the catchments. In contrast, the correlation dimension values of groundwater level displayed spatial patterns due to the different aquifer conditions (confined or unconfined). High correlation dimension values indicate partly confined conditions. In addition, Hurst analysis was involved to qualify the persistence of drought. It seems that drought mechanisms can be learnt from the data themselves in an inverse manner.

  10. Do selenium hyperaccumulators affect selenium speciation in neighboring plants and soil? An X-Ray Microprobe Analysis.

    PubMed

    El Mehdawi, Ali F; Lindblom, Stormy D; Cappa, Jennifer J; Fakra, Sirine C; Pilon-Smits, Elizabeth A H

    2015-01-01

    Neighbors of Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus were found earlier to have elevated Se levels. Here we investigate whether Se hyperaccumulators affect Se localization and speciation in surrounding soil and neighboring plants. X-ray fluorescence mapping and X-ray absorption near-edge structure spectroscopy were used to analyze Se localization and speciation in leaves of Artemisia ludoviciana, Symphyotrichum ericoides and Chenopodium album growing next to Se hyperaccumulators or non-accumulators at a seleniferous site. Regardless of neighbors, A. ludoviciana, S. ericoides and C. album accumulated predominantly (73-92%) reduced selenocompounds with XANES spectra similar to the C-Se-C compounds selenomethionine and methyl-selenocysteine. Preliminary data indicate that the largest Se fraction (65-75%), both in soil next to hyperaccumulator S. pinnata and next to nonaccumulator species was reduced Se with spectra similar to C-Se-C standards. These same C-Se-C forms are found in hyperaccumulators. Thus, hyperaccumulator litter may be a source of organic soil Se, but soil microorganisms may also contribute. These findings are relevant for phytoremediation and biofortification since organic Se is more readily accumulated by plants, and more effective for dietary Se supplementation.

  11. [Analysis of washing efficiency and change in lead speciation in lead-contaminated soil of a battery factory].

    PubMed

    Ren, Bei; Huang, Jin-lou; Miao, Ming-sheng

    2013-09-01

    Lead-contaminated soil with different pollution load in a lead battery factory in the southwest of China was chosen as the research object, the lead content and speciation were analyzed, and different washing agents were screened. The lead washing efficiency and lead speciation were analyzed under different pH conditions, and the soil of different particle size was washed using different duration to determine the best washing time. The results showed that the soil of sites A and B in the factory was severely contaminated, the lead concentration reaching 15,703.22 mg x kg(-1) and 1747.78 mg x kg(-1), respectively, and the proportion of the active-state lead was relatively high, while the residue state accounted for only 17.32%, 11.64%, 14.6% and 10.2%. EDTA and hydrochloric acid showed the best extraction effect in the 5 washing agents tested, which included EDTA, hydrochloric acid, citric acid, rhamnolipid and SDS. Cleaning under acidic conditions could not only effectively extract the total amount of lead but also effectively reduce the environmental risk of active-state lead. pH 4-7 was suggested as the most appropriate condition. The cleaning effect of coarse sand and fine sand was good, while for washing powder clay, it is better to improve the process, with the optimal washing time determined as 240 min.

  12. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; arsenic speciation in natural-water samples using laboratory and field methods

    USGS Publications Warehouse

    Garbarino, John R.; Bednar, Anthony J.; Burkhardt, Mark R.

    2002-01-01

    Analytical methods for the determination of arsenite [As(III)], arsenate [As(V)], dimethylarsinate (DMA), monomethylarsonate (MMA), and roxarsone in filtered natural-water samples are described. Various analytical methods can be used for the determination, depending on the arsenic species being determined. Arsenic concentration is determined by using inductively coupled plasma-mass spectrometry (ICP-MS) as an arsenic-specific detector for all methods. Laboratory-speciation methods are described that use an ion chromatographic column to separate the arsenic species; the column length, column packing, and mobile phase are dependent on the species of interest. Regardless of the separation technique, the arsenic species are introduced into plasma by eithe rpneumatic nebulization or arsine generation. Analysis times range from 2 to 8 minutes and method detection limits range from 0.1 to 0.6 microgram-arsenic per liter (ug-As/L), 10 to 60 picograms absolute (for a 100-microliter injection), depending on the arsenic species determined and the analytical method used. A field-generation specciation method also is described that uses a strong anion exchange cartridge to separate As(III) from As(V) in the field. As(III) in the eluate and the As(V) in the cartridge extract are determined by direct nebulization ICP-MS. Methylated arsenic species that also are retained on the cartridge will positively bias As(V) results without further laboratory separations. The method detection limit for field speciation is 0.3 ug-As/L. The distribution of arsenic species must be preserved in the field to eliminate changes caused by photochemical oxidation or metal oxyhydroxide precipitation. Preservation techniques, such as refrigeration, the addition of acides, or the additoin of ethylene-diaminetetraacetic acid (EDTA) and the effects of ambient light were tested. Of the preservatives evaluated, EDTA was found to work best with the laboratory- and field-speciation methods for all sample

  13. Nickel (II) Preconcentration and Speciation Analysis During Transport from Aqueous Solutions Using a Hollow-fiber Permeation Liquid Membrane (HFPLM) Device

    PubMed Central

    Bautista-Flores, Ana Nelly; de San Miguel, Eduardo Rodríguez; de Gyves, Josefina; Jönsson, Jan Åke

    2011-01-01

    Nickel (II) preconcentration and speciation analysis using a hollow fiber supported liquid membrane (HFSLM) device was studied. A counterflow of protons coupled to complexation with formate provided the driving force of the process, while Kelex 100 was employed as carrier. The influence of variables related to module configuration (acceptor pH and carrier concentration) and to the sample properties (donor pH) on the preconcentration factor, E, was simultaneously studied and optimized using a 3 factor Doehlert matrix response surface methodology. The effect of metal concentration was studied as well. Preconcentration factors as high as 4240 were observed depending on the values of the different variables. The effects of the presence of inorganic anions (NO2−, SO42−, Cl−, NO3−, CO32−, CN−) and dissolved organic matter (DOM) in the form of humic acids were additionally considered in order to carry out a speciation analysis study. Nickel preconcentration was observed to be independent of both effects, except when cyanide was present in the donor phase. A characterization of the transport regime was performed through the analysis of the dependence of E on the temperature. E increases with the increase in temperature according to the equation E(K) = −8617.3 + 30.5T with an activation energy of 56.7 kJ mol−1 suggesting a kinetic-controlled regime. Sample depletion ranged from 12 to 1.2% depending on the volume of the donor phase (100 to 1000 mL, respectively). PMID:24957733

  14. Analysis of sea ice dynamics

    NASA Technical Reports Server (NTRS)

    Zwally, J.

    1988-01-01

    The ongoing work has established the basis for using multiyear sea ice concentrations from SMMR passive microwave for studies of largescale advection and convergence/divergence of the Arctic sea ice pack. Comparisons were made with numerical model simulations and buoy data showing qualitative agreement on daily to interannual time scales. Analysis of the 7-year SMMR data set shows significant interannual variations in the total area of multiyear ice. The scientific objective is to investigate the dynamics, mass balance, and interannual variability of the Arctic sea ice pack. The research emphasizes the direct application of sea ice parameters derived from passive microwave data (SMMR and SSMI) and collaborative studies using a sea ice dynamics model. The possible causes of observed interannual variations in the multiyear ice area are being examined. The relative effects of variations in the large scale advection and convergence/divergence within the ice pack on a regional and seasonal basis are investigated. The effects of anomolous atmospheric forcings are being examined, including the long-lived effects of synoptic events and monthly variations in the mean geostrophic winds. Estimates to be made will include the amount of new ice production within the ice pack during winter and the amount of ice exported from the pack.

  15. Simultaneous iron, zinc, sulfur and phosphorus speciation analysis of barley grain tissues using SEC-ICP-MS and IP-ICP-MS.

    PubMed

    Persson, Daniel P; Hansen, Thomas H; Laursen, Kristian H; Schjoerring, Jan K; Husted, Søren

    2009-09-01

    The increasing prevalence of iron (Fe) and zinc (Zn) deficiencies in human populations worldwide has stressed the need for more information about the distribution and chemical speciation of these elements in cereal products. In order to investigate these aspects, barley grains were fractionated into awns, embryo, bran and endosperm and analysed for Fe and Zn. Simultaneously, phosphorus (P) and sulfur (S) were determined since these elements are major constituents of phytic acid and proteins, respectively, compounds which are potentially involved in Fe and Zn binding. A novel analytical method was developed in which oxygen was added to the octopole reaction cell of the ICP-MS. This approach greatly improved the sensitivity of sulfur, measured as (48)SO(+). Simultaneously, Fe was measured as (72)FeO(+), P as (47)PO(+), and Zn as (66)Zn(+), enabling sensitive and simultaneous analysis of these four elements. The highest concentrations of Zn, Fe, S and P were found in the bran and embryo fractions. Further analysis of the embryo using SEC-ICP-MS revealed that the speciation of Fe and Zn differed. The majority of Fe co-eluted with P as a species with the apparent mass of 12.3 kDa, whereas the majority of Zn co-eluted with S as a 3 kDa species, devoid of any co-eluting P. Subsequent ion pairing chromatography of the Fe/P peak showed that phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate: IP(6)) was the main Fe binding ligand, with the stoichiometry Fe(4)(IP(6))(18). When incubating the embryo tissue with phytase, the enzyme responsible for degradation of phytic acid, the extraction efficiency of both Fe and P was doubled, whereas that of Zn and S was unaffected. Protein degradation on the other hand, using protease XIV, boosted the extraction of Zn and S, but not that of Fe and P. It is concluded that Fe and Zn have a different speciation in cereal grain tissues; Zn appears to be mainly bound to peptides, while Fe is mainly associated with phytic acid.

  16. Ultra-Sensitive Elemental Analysis Using Plasmas 5.Speciation of Arsenic Compounds in Biological Samples by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry System

    NASA Astrophysics Data System (ADS)

    Kaise, Toshikazu

    Arsenic originating from the lithosphere is widely distributed in the environment. Many arsenicals in the environment are in organic and methylated species. These arsenic compounds in drinking water or food products of marine origin are absorbed in human digestive tracts, metabolized in the human body, and excreted viatheurine. Because arsenic shows varying biological a spects depending on its chemical species, the biological characteristics of arsenic must be determined. It is thought that some metabolic pathways for arsenic and some arsenic circulation exist in aqueous ecosystems. In this paper, the current status of the speciation analysis of arsenic by HPLC/ICP-MS (High Performance Liquid Chromatography-Inductively Coupled Plasma Mass spectrometry) in environmental and biological samples is summarized using recent data.

  17. Speciation and bifurcations.

    PubMed

    Volkenstein, M V; Livshits, M A

    1989-01-01

    The interrelations of physics and biology are discussed. It is shown that Darwin can be considered as one of the founders of the important field of contemporary physics called physics of dissipative structures or synergetics. The theories of gradual and punctual evolution are presented. The contradiction between these theories can be solved on the basis of molecular theory of evolution and on the basis of the phenomenological physical treatment. The general physical properties of living systems, considered as open systems being far from equilibrium, are listed and simple non-linear mathematical models describing gradual and punctual speciation are suggested. The usual pictures which present these two kinds of speciation can possess physico-mathematical sense. Punctuated speciation means bifurcation, a kind of non-equilibrium phase transition.

  18. Speciation genes in plants

    PubMed Central

    Rieseberg, Loren H.; Blackman, Benjamin K.

    2010-01-01

    Background Analyses of speciation genes – genes that contribute to the cessation of gene flow between populations – can offer clues regarding the ecological settings, evolutionary forces and molecular mechanisms that drive the divergence of populations and species. This review discusses the identities and attributes of genes that contribute to reproductive isolation (RI) in plants, compares them with animal speciation genes and investigates what these genes can tell us about speciation. Scope Forty-one candidate speciation genes were identified in the plant literature. Of these, seven contributed to pre-pollination RI, one to post-pollination, prezygotic RI, eight to hybrid inviability, and 25 to hybrid sterility. Genes, gene families and genetic pathways that were frequently found to underlie the evolution of RI in different plant groups include the anthocyanin pathway and its regulators (pollinator isolation), S RNase-SI genes (unilateral incompatibility), disease resistance genes (hybrid necrosis), chimeric mitochondrial genes (cytoplasmic male sterility), and pentatricopeptide repeat family genes (cytoplasmic male sterility). Conclusions The most surprising conclusion from this review is that identities of genes underlying both prezygotic and postzygotic RI are often predictable in a broad sense from the phenotype of the reproductive barrier. Regulatory changes (both cis and trans) dominate the evolution of pre-pollination RI in plants, whereas a mix of regulatory mutations and changes in protein-coding genes underlie intrinsic postzygotic barriers. Also, loss-of-function mutations and copy number variation frequently contribute to RI. Although direct evidence of positive selection on speciation genes is surprisingly scarce in plants, analyses of gene family evolution, along with theoretical considerations, imply an important role for diversifying selection and genetic conflict in the evolution of RI. Unlike in animals, however, most candidate speciation

  19. Dynamical analysis of highly excited molecular spectra

    SciTech Connect

    Kellman, M.E.

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  20. Speciation analysis of mercury in sediments, zoobenthos and river water samples by high-performance liquid chromatography hyphenated to atomic fluorescence spectrometry following preconcentration by solid phase extraction.

    PubMed

    Margetínová, Jana; Houserová-Pelcová, Pavlína; Kubán, Vlastimil

    2008-05-19

    A high-pressure microwave digestion was applied for microwave-assisted extraction (MAE) of mercury species from sediments and zoobenthos samples. A mixture containing 3molL(-1) HCl, 50% aqueous methanol and 0.2molL(-1) citric acid (for masking co-extracted Fe(3+)) was selected as the most suitable extraction agent. The efficiency of proposed extraction method was better than 95% with R.S.D. below 6%. A preconcentration method utilizing a "homemade" C18 solid phase extraction (SPE) microcolumns was developed to enhance sensitivity of the mercury species determination using on-column complex formation of mercury-2-mercaptophenol complexes. Methanol was chosen for counter-current elution of the retained mercury complexes achieving a preconcentration factor as much as 1000. The preconcentration method was applied for the speciation analysis of mercury in river water samples. The high-performance liquid chromatography-cold vapour atomic fluorescence spectrometric (HPLC/CV-AFS) method was used for the speciation analysis of mercury. The complete separation of four mercury species was achieved by an isocratic elution of aqueous methanol (65%/35%) on a Zorbax SB-C18 column (4.6mmx150mm, 5microm) using the same complexation reagent (2-mercaptophenol). The limits of detection were 4.3microg L(-1) for methylmercury (MeHg(+)), 1.4microg L(-1) for ethylmercury (EtHg(+)), 0.8microg L(-1) for inorganic mercury (Hg(2+)), 0.8microg L(-1) for phenylmercury (PhHg(+)).

  1. How does climate influence speciation?

    PubMed

    Hua, Xia; Wiens, John J

    2013-07-01

    Variation in climatic conditions over space and time is thought to be an important driver of speciation. However, the role of climate has not been explored in the theoretical literature on speciation, and the theory underlying empirical studies of climate and speciation has come largely from informal, verbal models. In this study, we develop a quantitative model to test a relatively new but theoretically untested model of speciation (speciation via niche conservatism) and to examine the climatic conditions under which speciation via niche conservatism and speciation via niche divergence are most plausible. Our results have three broad implications for the study of speciation: (1) ecological similarity over time (niche conservatism) can be an important part of speciation, despite the traditional emphasis on ecological divergence, (2) long-term directional climate change promotes speciation via niche conservatism for species with low climatic-niche lability, whereas climatic oscillations promote speciation via niche divergence for species with high climatic-niche lability, and (3) population extinction can be a key component of speciation.

  2. Arsenic Speciation in Groundwater: Role of Thioanions

    NASA Astrophysics Data System (ADS)

    Wilkin, R. T.; Ford, R. G.; Beak, D. G.

    2008-12-01

    The behavior of arsenic in groundwater environments is fundamentally linked to its speciation. Understanding arsenic speciation is important because chemical speciation impacts reactivity, bioavailability, toxicity, and transport and fate processes. In aerobic environments arsenic is mainly present as arsenate. In the subsurface, reducing conditions frequently prevail and arsenite species dominate. At sites where groundwater remediation is necessary, understanding arsenic speciation is critical, especially when technologies that strategically manipulate redox conditions are used. In sulfate-reducing environments and where free sulfide is available thioarsenic species are known to exist, yet compared to the oxyanion species of arsenic little is know about the formation, structure, chemistry, and stability of arsenic thioanions in the environment. In particular, data are lacking that pertain to the redox behavior of arsenate and arsenite in the presence of aqueous sulfide and at variable pH. In this presentation, results are discussed of recent speciation studies using extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge spectroscopy (XANES), and chromatographic analysis. Data from both experimental and field systems will be presented. Results indicate that both thioarsenite and thioarsenate species exist and both forms of thioarsenic species need to be considered in sulfidic environments. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.

  3. Vehicle systems: coupled and interactive dynamics analysis

    NASA Astrophysics Data System (ADS)

    Vantsevich, Vladimir V.

    2014-11-01

    This article formulates a new direction in vehicle dynamics, described as coupled and interactive vehicle system dynamics. Formalised procedures and analysis of case studies are presented. An analytical consideration, which explains the physics of coupled system dynamics and its consequences for dynamics of a vehicle, is given for several sets of systems including: (i) driveline and suspension of a 6×6 truck, (ii) a brake mechanism and a limited slip differential of a drive axle and (iii) a 4×4 vehicle steering system and driveline system. The article introduces a formal procedure to turn coupled system dynamics into interactive dynamics of systems. A new research direction in interactive dynamics of an active steering and a hybrid-electric power transmitting unit is presented and analysed to control power distribution between the drive axles of a 4×4 vehicle. A control strategy integrates energy efficiency and lateral dynamics by decoupling dynamics of the two systems thus forming their interactive dynamics.

  4. Dynamics Analysis of Wind Energy Production Development

    NASA Astrophysics Data System (ADS)

    Berg, V. I.; Zakirzakov, A. G.; Gordievskaya, E. F.

    2017-01-01

    The paper presents the analysis of the introduction experience and dynamics development of the world wind energy production. Calculated the amount of wind energy sources investments and the production capacity growth dynamics of the wind turbines. The studies have shown that the introduction dynamics of new wind energy sources is higher than any other energy source.

  5. [XANES study of lead speciation in duckweed].

    PubMed

    Chu, Bin-Bin; Luo, Li-Qiang; Xu, Tao; Yuan, Jing; Sun, Jian-Ling; Zeng, Yuan; Ma, Yan-Hong; Yi, Shan

    2012-07-01

    Qixiashan lead-zinc mine of Nanjing was one of the largest lead zinc deposits in East China Its exploitation has been over 50 years, and the environmental pollution has also been increasing. The lead concentration in the local environment was high, but lead migration and toxic mechanism has not been clear. Therefore, biogeochemistry research of the lead zinc mine was carried out. Using ICP-MS and Pb-L III edge XANES, lead concentration and speciation were analyzed respectively, and duckweed which can tolerate and enriched heavy metals was found in the pollution area. The results showed that the lead concentration of duckweed was 39.4 mg x kg(-1). XANES analysis and linear combination fit indicated that lead stearate and lead sulfide accounted for 65% and 36.9% respectively in the lead speciation of duckweed, suggesting that the main lead speciation of duckweed was sulfur-containing lead-organic acid.

  6. Instrumentation for Aerosol and Gas Speciation

    NASA Technical Reports Server (NTRS)

    Coggiola, Michael J.

    1998-01-01

    Using support from NASA Grant No. NAG 2-963, SRI International successfully completed the project, entitled, 'Instrumentation for Aerosol and Gas Speciation.' This effort (SRI Project 7383) covered the design, fabrication, testing, and deployment of a real-time aerosol speciation instrument in NASA's DC-8 aircraft during the Spring 1996 SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) mission. This final technical report describes the pertinent details of the instrument design, its abilities, its deployment during SUCCESS and the data acquired from the mission, and the post-mission calibration, data reduction, and analysis.

  7. Speciation: more likely through a genetic or through a learned habitat preference?

    PubMed Central

    Beltman, J.B; Metz, J.A.J

    2005-01-01

    A problem in understanding sympatric speciation is establishing how reproductive isolation can arise when there is disruptive selection on an ecological trait. One of the solutions that has been proposed is that a habitat preference evolves, and that mates are chosen within the preferred habitat. We present a model where the habitat preference can evolve either by means of a genetic mechanism or by means of learning. Employing an adaptive-dynamical analysis, we show that evolution proceeds either to a single population of specialists with a genetic preference for their optimal habitat, or to a population of generalists without a habitat preference. The generalist population subsequently experiences disruptive selection. Learning promotes speciation because it increases the intensity of disruptive selection. An individual-based version of the model shows that, when loci are completely unlinked and learning confers little cost, the presence of disruptive selection most probably leads to speciation via the simultaneous evolution of a learned habitat preference. For high costs of learning, speciation is most likely to occur via the evolution of a genetic habitat preference. However, the latter only happens when the effect of mutations is large, or when there is linkage between genes coding for the different traits. PMID:16011920

  8. Speciation: more likely through a genetic or through a learned habitat preference?

    PubMed

    Beltman, J B; Metz, J A J

    2005-07-22

    A problem in understanding sympatric speciation is establishing how reproductive isolation can arise when there is disruptive selection on an ecological trait. One of the solutions that has been proposed is that a habitat preference evolves, and that mates are chosen within the preferred habitat. We present a model where the habitat preference can evolve either by means of a genetic mechanism or by means of learning. Employing an adaptive-dynamical analysis, we show that evolution proceeds either to a single population of specialists with a genetic preference for their optimal habitat, or to a population of generalists without a habitat preference. The generalist population subsequently experiences disruptive selection. Learning promotes speciation because it increases the intensity of disruptive selection. An individual-based version of the model shows that, when loci are completely unlinked and learning confers little cost, the presence of disruptive selection most probably leads to speciation via the simultaneous evolution of a learned habitat preference. For high costs of learning, speciation is most likely to occur via the evolution of a genetic habitat preference. However, the latter only happens when the effect of mutations is large, or when there is linkage between genes coding for the different traits.

  9. Direct speciation analysis of thallium based on solid phase extraction and specific retention of a Tl(III) complex on alumina coated with sodium dodecyl sulfate.

    PubMed

    Biaduń, Ewa; Sadowska, Monika; Ospina-Alvarez, Natalia; Krasnodębska-Ostręga, Beata

    Alumina (Al2O3) with an average particle size of 63 μm was modified with the anionic surfactant sodium dodecyl sulfate (SDS) and then applied to (i) solid phase extraction and separation of both thallium(I) and thallium(III), and (ii) preconcentration of Tl(III) from waste water samples. Only Tl(III), in the form of its complex with diethylenetriaminepentaacetate (DTPA), was retained on the sorbent, from where it can be eluted with 40 % nitric acid. Thallium species were then quantified by ICP MS. The method was characterized by a LOD of 25 pg of Tl(I) and 160 pg of Tl(III) in 10 mL samples. A large excesses of Tl(I) over Tl(III) was tolerated, and relatively high levels of other metal ions, such as a 500-fold excess of Pb(II) and Cd(II), and a 2000-fold excess of Zn(II), respectively, do not interfere. The sorbent was easily prepared and possesses a high loading capacity, and these properties make it an attractive material for rapid and efficient extraction and speciation of Tl. Graphical abstract:Schematic of the SPE procedure for separation (with preconcentration) of Tl(III) from Tl(I) was developed and applied to direct speciation analysis of thallium in wastewater. Self-made columns packed with alumina coated with SDS were used. The method is resistant to interferences from Pb, Cd, Zn and tolerates a large excess of Tl(I) over Tl(III).

  10. Chapter A5. Section 6.4.A. Arsenic Speciation

    USGS Publications Warehouse

    Garbarino, John R.

    2005-01-01

    Two sample-processing methods (field speciation and laboratory speciation) used at the USGS National Water Quality Laboratory (NWQL) are specific to sample analysis by inductively coupled plasma-mass spectrometry (ICP-MS) for determining the concentration of inorganic and organic arsenic species in a water sample. The field-speciation method requires NWQL Schedule 1729. The laboratory-speciation method requires use either of NWQL Schedule 1730, 1731, or 1732, as appropriate for study objectives. For either the field- or laboratory-speciation method, prior knowledge is needed of sample matrix-composition characteristics (that is, major-ion concentrations in filtered samples). Major-ion data are necessary to determine (1) the volume of ethylenediaminetetraacetic acid (EDTA) that will be required for sample preservation, and (2) if sample dilution is required.

  11. Speciation analysis of bromine-containing drug metabolites in feces samples from a human in vivo study by means of HPLC/ICP-MS combined with on-line isotope dilution.

    PubMed

    Meermann, Björn; Bockx, Marc; Laenen, Aline; Van Looveren, Cis; Cuyckens, Filip; Vanhaecke, Frank

    2012-01-01

    The aim of this work was speciation analysis of metabolites in feces samples collected within a clinical study during which a bromine-containing anti-tuberculosis drug (TMC207) was administered to patients with multi-drug resistant tuberculosis infection. Owing to slow elimination of the drug, no (14)C label was used within this study. Quantification of the bromine species was accomplished using high performance liquid chromatography coupled to inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) in combination with on-line isotope dilution (on-line ID), while structural elucidation of the species was performed using HPLC coupled to electrospray ionization-mass spectrometry. The ICP-MS-based method developed shows a good intra- and inter-day reproducibility (relative standard deviation = 3.5%, N = 9); the limit of detection (1.5 mg TMC207 L(-1)) is of the same order of magnitude as that for HPLC/radiodetection; the dynamic range of the method covers more than two orders of magnitude. Furthermore, the column recovery was demonstrated to be quantitative (recoveries between 90.6% and 99.5%). Based on the excellent figures of merit, the "cold" HPLC/ICP-MS approach could be deployed for the actual human in vivo metabolism study, such that exposure of the human volunteers to the (14)C radiolabel was avoided.

  12. Arsenic speciation in edible mushrooms.

    PubMed

    Nearing, Michelle M; Koch, Iris; Reimer, Kenneth J

    2014-12-16

    The fruiting bodies, or mushrooms, of terrestrial fungi have been found to contain a high proportion of the nontoxic arsenic compound arsenobetaine (AB), but data gaps include a limited phylogenetic diversity of the fungi for which arsenic speciation is available, a focus on mushrooms with higher total arsenic concentrations, and the unknown formation and role of AB in mushrooms. To address these, the mushrooms of 46 different fungus species (73 samples) over a diverse range of phylogenetic groups were collected from Canadian grocery stores and background and arsenic-contaminated areas. Total arsenic was determined using ICP-MS, and arsenic speciation was determined using HPLC-ICP-MS and complementary X-ray absorption spectroscopy (XAS). The major arsenic compounds in mushrooms were found to be similar among phylogenetic groups, and AB was found to be the major compound in the Lycoperdaceae and Agaricaceae families but generally absent in log-growing mushrooms, suggesting the microbial community may influence arsenic speciation in mushrooms. The high proportion of AB in mushrooms with puffball or gilled morphologies may suggest that AB acts as an osmolyte in certain mushrooms to help maintain fruiting body structure. The presence of an As(III)-sulfur compound, for the first time in mushrooms, was identified in the XAS analysis. Except for Agaricus sp. (with predominantly AB), inorganic arsenic predominated in most of the store-bought mushrooms (albeit with low total arsenic concentrations). Should inorganic arsenic predominate in these mushrooms from contaminated areas, the risk to consumers under these circumstances should be considered.

  13. Dynamic Hurricane Data Analysis Tool

    NASA Technical Reports Server (NTRS)

    Knosp, Brian W.; Li, Peggy; Vu, Quoc A.

    2009-01-01

    A dynamic hurricane data analysis tool allows users of the JPL Tropical Cyclone Information System (TCIS) to analyze data over a Web medium. The TCIS software is described in the previous article, Tropical Cyclone Information System (TCIS) (NPO-45748). This tool interfaces with the TCIS database to pull in data from several different atmospheric and oceanic data sets, both observed by instruments. Users can use this information to generate histograms, maps, and profile plots for specific storms. The tool also displays statistical values for the user-selected parameter for the mean, standard deviation, median, minimum, and maximum values. There is little wait time, allowing for fast data plots over date and spatial ranges. Users may also zoom-in for a closer look at a particular spatial range. This is version 1 of the software. Researchers will use the data and tools on the TCIS to understand hurricane processes, improve hurricane forecast models and identify what types of measurements the next generation of instruments will need to collect.

  14. Systems-Dynamic Analysis for Neighborhood Study

    EPA Science Inventory

    Systems-dynamic analysis (or system dynamics (SD)) helps planners identify interrelated impacts of transportation and land-use policies on neighborhood-scale economic outcomes for households and businesses, among other applications. This form of analysis can show benefits and tr...

  15. Systems-Dynamic Analysis for Neighborhood Study

    EPA Science Inventory

    Systems-dynamic analysis (or system dynamics (SD)) helps planners identify interrelated impacts of transportation and land-use policies on neighborhood-scale economic outcomes for households and businesses, among other applications. This form of analysis can show benefits and tr...

  16. Evaluating Oil and Gas Speciation Profiles with Factor Analysis of Ambient Volatile Organic Compound Concentrations in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Capps, S.; Paranjothi, G.; Pierce, G. E.; Milford, J. B.

    2016-12-01

    Increased oil and gas (O&G) development, particularly through the use of hydraulic fracturing, in the Denver-Julesburg Basin (DJB) in Colorado over the last decade has been identified as a source of emissions of air pollutants, which are now included in chemical transport modeling. As one effort to evaluate its impact, ambient concentrations of volatile organic compounds (VOCs) that serve as precursors to ozone formation were measured in an Ozone Precursor Study conducted by the Colorado Department of Public Health and Environment during 2013 and 2014. The study included 6 - 9 a.m. measurements of an extensive suite of ozone-precursor VOCs from a site in an area of intensive O&G development in Platteville, CO, and another site in downtown Denver, CO. To evaluate the influences of urban activity or O&G development on these ambient concentrations, we used the U.S. EPA's Positive Matrix Factorization (PMF) tool. A five-factor PMF solution was selected as providing the best fit to the dataset comprised of VOC measurements for both years and both sites. One PMF factor matches the VOC emissions speciation profile for the flashing gas composition for condensate tanks in the DJB that was developed by the Western Regional Air Partnership for use in chemical transport modeling in the region. The contribution of this factor to individual and total VOC concentrations and ozone production reactivity is evaluated for Platteville and Denver.

  17. Strontium speciation during reaction of kaolinite with simulated tank-waste leachate: bulk and microfocused EXAFS analysis.

    PubMed

    Choi, Sunkyung; O'Day, Peggy A; Rivera, Nelson A; Mueller, Karl T; Vairavamurthy, Murthy A; Seraphin, Supapan; Chorover, Jon

    2006-04-15

    Radioactive strontium (90Sr) is an important constituent of the complex wastes from past nuclear weapons production and has been stored in underground tanks at U.S. DOE sites (e.g., Hanford, WA). Using bulk and microfocused EXAFS spectroscopy, we examined temporal changes in solid-phase Sr speciation in kaolinite samples reacted for 1-369 d with high-pH, high ionic strength synthetic tank-waste leachate containing Sr(2+) and Cs(+) at 10(-3) mol kg(-1). Analyses of bulk EXAFS spectra showed that Sr initially forms a precipitate by 7 d with a local structure similar to SrCO(3-) (s). At 33 d, microfocused EXAFS of individual particles in one sample revealed a mixture of hydrated and dehydrated Sr associated with neoformed sodalite-type phases. At aging times of 93 d and longer, bulk EXAFS spectra and supporting characterizations indicated nonexchangeable Sr with a local structure consistent with incorporation into increasingly crystalline aluminosilicate particles, particularly sodalite. These experimental studies suggest that irreversible trapping of radionuclides occurs if they are present during the formation and aging of feldspathoid alteration products of local Si-bearing sediment minerals. This may serve as an effective contaminant sequestration mechanism at sites such as Hanford.

  18. Strontium Speciation During Reactin of Kaolinite with Simulated Tank-Waste Leachate: Bulk and Microfocused EXAFS Analysis

    SciTech Connect

    Choi,S.; O'Day, P.; Riveria, N.; Mueller, K.; Seraphin, S.; Chorover, J.

    2006-01-01

    Radioactive strontium ({sup 90}Sr) is an important constituent of the complex wastes from past nuclear weapons production and has been stored in underground tanks at U.S. DOE sites (e.g., Hanford, WA). Using bulk and microfocused EXAFS spectroscopy, we examined temporal changes in solid-phase Sr speciation in kaolinite samples reacted for 1-369 d with high-pH, high ionic strength synthetic tank-waste leachate containing Sr{sup 2+} and Cs{sup +} at 10{sup -3} mol kg{sup -1}. Analyses of bulk EXAFS spectra showed that Sr initially forms a precipitate by 7 d with a local structure similar to SrCO{sub 3}(s). At 33 d, microfocused EXAFS of individual particles in one sample revealed a mixture of hydrated and dehydrated Sr associated with neoformed sodalite-type phases. At aging times of 93 d and longer, bulk EXAFS spectra and supporting characterizations indicated nonexchangeable Sr with a local structure consistent with incorporation into increasingly crystalline aluminosilicate particles, particularly sodalite. These experimental studies suggest that irreversible trapping of radionuclides occurs if they are present during the formation and aging of feldspathoid alteration products of local Si-bearing sediment minerals. This may serve as an effective contaminant sequestration mechanism at sites such as Hanford.

  19. Selective sorption behavior of iodine species on an activated carbon disk and its implication for the speciation analysis

    NASA Astrophysics Data System (ADS)

    Yoon, H.; Lee, J.; An, J.

    2013-12-01

    In recent times, iodate (IO3-) which can be generated under highly oxidized conditions such as the ozonation process in a water treatment plant has been receiving increasing attention due to its high toxicity to human and environment. In this respect, sorption behavior of iodide (I-) and IO3- on an activated carbon (AC) disk as a solid sorbent was investigated for the further development of efficient removal and analytical techniques. To this end, batch sorption tests were performed as a function of pH, sample volume, and initial concentration. Sorption of I- occurred preferentially on the surface of AC disk, regardless of pH levels (i.e., 4, 6, and 8). However, IO3- was quite sensitive to pH levels and the sorption capability of IO3- on the AC disk was much smaller than that of I-. Maximum sorption capacities of I- and IO3- in the different matrices (i.e., deionized water and seawater) were also assessed. In addition, the analytical strategy for the iodine speciation was also introduced. Iodine species were separated and pre-concentrated onto the AC disk based on their selective sorption properties according to the pH levels. Then, the AC disk pre-concentrated was directly analyzed using wavelength dispersive X-ray fluorescence spectrometry. Acknowledgement This research was supported by a grant from the Korea Basic Science Institute (project No. E33300).

  20. Tellurium speciation analysis using hydride generation in situ trapping electrothermal atomic absorption spectrometry and ruthenium or palladium modified graphite tubes.

    PubMed

    Yildirim, Emrah; Akay, Pınar; Arslan, Yasin; Bakirdere, Sezgin; Ataman, O Yavuz

    2012-12-15

    Speciation of tellurium can be achieved by making use of different kinetic behaviors of Te(IV) and Te(VI) upon their reaction with sodium borohydride using hydride generation. While Te(IV) can form H(2)Te, Te(VI) will not form any volatile species during the course of hydride formation and measurement by atomic absorption spectrometry. Quantitative reduction of Te(VI) was achieved through application of a microwave assisted prereduction of Te(VI) in 6.0 mol/L HCl solution. Enhanced sensitivity was achieved by in situ trapping of the generated H(2)Te species in a previously heated graphite furnace whose surface was modified using Pd or Ru. Overall efficiency for in situ trapping in pyrolytically coated graphite tube surface was found to be 15% when volatile analyte species are trapped for 60s at 300°C. LOD and LOQ values were calculated as 0.086 ng/mL and 0.29 ng/mL, respectively. Efficiency was increased to 46% and 36% when Pd and Ru surface modifiers were used, respectively. With Ru modified graphite tube 173-fold enhancement was obtained over 180 s trapping period with respect to ETAAS; the tubes could be used for 250 cycles. LOD values were 0.0064 and 0.0022 ng/mL for Pd and Ru treated ETAAS systems, respectively, for 180 s collection of 9.6 mL sample solution.

  1. Nested biological variation and speciation

    PubMed Central

    Foster, S. A.

    1998-01-01

    The modes of speciation that are thought to have contributed most to the generation of biodiversity require population differentiation as the initial stage in the speciation process. Consequently, a complete understanding of the mechanisms of speciation requires that the process be examined not just after speciation is complete, or nearly so, but also much earlier. Because reproductive isolation defines biological species, and it evolves slowly, study of the process may require a prohibitive span of time. Even if speciation could be observed directly, selection of populations in the process of speciation is typically difficult or impossible, because those that will ultimately undergo speciation cannot be distinguished from those that will differentiate but never assume the status of new biological species. One means of circumventing this problem is to study speciation in taxa comprising several sibling species, at least one of which exhibits extensive population differentiation. We illustrate this approach by exploring patterns of population variation in the post-glacial radiation of the threespine stickleback, Gasterosteus aculeatus. We focus on lacustrine populations and species within this complex, demonstrating parallel axes of divergence within populations, among populations and among species. The pattern that emerges is one of parallel relationships between phenotype and fitness at all three hierarchical levels, a pattern that facilitates exploration of the causes and consequences of speciation and secondary contact. A second outcome of this exploration is the observation that speciation can be the consequence of a cascade of effects, beginning with selection on trophic or other characteristics that in turn force the evolution of other population characteristics that precipitate speciation. Neither of these conclusions could have been reached without comparative studies of wild populations at several hierarchical levels, a conclusion reinforced by a brief

  2. Speciation analysis of silver nanoparticles and silver ions in antibacterial products and environmental waters via cloud point extraction-based separation.

    PubMed

    Chao, Jing-bo; Liu, Jing-fu; Yu, Su-juan; Feng, Ying-di; Tan, Zhi-qiang; Liu, Rui; Yin, Yong-guang

    2011-09-01

    The rapid growth in commercial use of silver nanoparticles (AgNPs) will inevitably increase silver exposure in the environment and the general population. As the fate and toxic effects of AgNPs is related to the Ag(+) released from AgNPs and the transformation of Ag(+) into AgNPs, it is of great importance to develop methods for speciation analysis of AgNPs and Ag(+). This study reports the use of Triton X-114-based cloud point extraction as an efficient separation approach for the speciation analysis of AgNPs and Ag(+) in antibacterial products and environmental waters. AgNPs were quantified by determining the Ag content in the Triton X-114-rich phase with inductively coupled plasma mass spectrometry (ICPMS) after microwave digestion. The concentration of total Ag(+), which consists of the AgNP adsorbed, the matrix associated, and the freely dissolved, was obtained by subtracting the AgNP content from the total silver content that was determined by ICPMS after digestion. The limits of quantification (S/N = 10) for antibacterial products were 0.4 μg/kg and 0.2 μg/kg for AgNPs and total silver, respectively. The reliable quantification limit was 3 μg/kg for total Ag(+). The presence of Ag(+) at concentrations up to 2-fold that of AgNPs caused no effects on the determination of AgNPs. In the cloud point extraction of AgNPs in antibacterial products, the spiked recoveries of AgNPs were in the range of 71.7-103% while the extraction efficiencies of Ag(+) were in the range of 1.2-10%. The possible coextracted other silver containing nanoparticles in the cloud point extraction of AgNPs were distinguished by transmission electron microscopy (TEM), scanning electron microscopy (SEM)- energy dispersive spectroscopy (EDS), and UV-vis spectrum. Real sample analysis indicated that even though the manufacturers claimed nanosilver products, AgNPs were detected only in three of the six tested antibacterial products.

  3. Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer).

    EPA Science Inventory

    This paper describes an automated system for the oxidation state specific speciation of inorganic and methylated arsenicals by selective hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer. The corresponding arsines are ge...

  4. Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer).

    EPA Science Inventory

    This paper describes an automated system for the oxidation state specific speciation of inorganic and methylated arsenicals by selective hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer. The corresponding arsines are ge...

  5. Speciation in ancient lakes.

    PubMed

    Martens, K

    1997-05-01

    About a dozen lakes in the world are up to three orders of magnitude older than most others. Lakes Tanganyika (East Africa) and Baikal (Siberia) have probably existed in some form for 12-20 million years, maybe more. Such lakes can have different origins, sizes, shapes, depths and limnologies, but, in contrast to short-lived (mostly post-glacial) lakes, they have exceptionally high faunal diversity and levels of endemicity. A multitude of and processes accounting for these explosive radiations have recently been documented, most of them based on particular groups in certain lakes, but comparative research can detect repeated patterns. No special speciafion mechanism, exclusive to ancient lakes has been demonstrated, although cases of ultra-rapid speciation have been documented. Extant diversity results not by simple accumulation, but by a complex process of immigration, speciation and extinction.

  6. A model of sympatric speciation through assortative mating

    NASA Astrophysics Data System (ADS)

    Bagnoli, Franco; Guardiani, Carlo

    2005-03-01

    A microscopic model is developed, within the frame of the theory of quantitative traits, to study the combined effect of competition and assortativity on the sympatric speciation process, i.e., speciation in the absence of geographical barriers. Two components of fitness are considered: a static one that describes adaptation to environmental factors not related to the population itself, and a dynamic one that accounts for interactions between organisms, e.g. competition. A simulated annealing technique was applied in order to speed up simulations. The simulations show that both in the case of flat and steep static fitness landscapes, competition and assortativity do exert a synergistic effect on speciation. We also show that competition acts as a stabilizing force against extinction due to random sampling in a finite population. Finally, evidence is shown that speciation can be seen as a phase transition.

  7. Dynamic Blowout Risk Analysis Using Loss Functions.

    PubMed

    Abimbola, Majeed; Khan, Faisal

    2017-08-11

    Most risk analysis approaches are static; failing to capture evolving conditions. Blowout, the most feared accident during a drilling operation, is a complex and dynamic event. The traditional risk analysis methods are useful in the early design stage of drilling operation while falling short during evolving operational decision making. A new dynamic risk analysis approach is presented to capture evolving situations through dynamic probability and consequence models. The dynamic consequence models, the focus of this study, are developed in terms of loss functions. These models are subsequently integrated with the probability to estimate operational risk, providing a real-time risk analysis. The real-time evolving situation is considered dependent on the changing bottom-hole pressure as drilling progresses. The application of the methodology and models are demonstrated with a case study of an offshore drilling operation evolving to a blowout. © 2017 Society for Risk Analysis.

  8. Dynamic Analysis of AN Automatic Dynamic Balancer for Rotating Mechanisms

    NASA Astrophysics Data System (ADS)

    CHUNG, J.; RO, D. S.

    1999-12-01

    Dynamic stability and behavior of an automatic dynamic balance (ADB) are analyzed by a theoretical approach. Using Lagrange's equation, we derive the non-linear equations of motion for an autonomous system with respect to the polar co-ordinate system. From the equations of motion for the autonomous system, the equilibrium positions and the linear variational equations are obtained by the perturbation method. Based on the variational equations, the dynamic stability of the system in the neighborhood of the equilibrium positions is investigated by the Routh-Hurwitz criteria. The results of the stability analysis provide the design requirements for the ADB to achieve balancing of the system. In addition, in order to verify the stability of the system, time responses are computed by the generalized-α method. We also investigate the dynamic behavior of the system and the effects of damping on balancing.

  9. Ultra-sensitive speciation analysis of mercury by CE-ICP-MS together with field-amplified sample stacking injection and dispersive solid-phase extraction.

    PubMed

    Chen, YiQuan; Cheng, Xian; Mo, Fan; Huang, LiMei; Wu, Zujian; Wu, Yongning; Xu, LiangJun; Fu, FengFu

    2016-04-01

    A simple dispersive solid-phase extraction (DSPE) used to extract and preconcentrate ultra-trace MeHg, EtHg and Hg(2+) from water sample, and a sensitive method for the simultaneous analysis of MeHg, EtHg and Hg(2+) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) with field-amplified sample stacking injection (FASI) were first reported in this study. The DSPE used thiol cotton particles as adsorbent, and is simple and effective. It can be used to extract and preconcentrate ultra-trace mercury compounds in water samples within 30 min with a satisfied recovery and no mercury species alteration during the process. The FASI enhanced the sensitivity of CE-ICP-MS with 25-fold, 29-fold and 27-fold for MeHg, EtHg and Hg(2+) , respectively. Using FASI-CE-ICP-MS together with DSPE, we have successfully determined ultra-trace MeHg, EtHg and Hg(2+) in tap water with a limits of quantification (LOQs) of 0.26-0.45 pg/mL, an RSD (n = 3) < 6% and a recovery of 92-108%. Ultra-high sensitivity, as well as much less sample and reagent consumption and low operating cost, make our method a valuable technique to the speciation analysis of ultra-trace mercury.

  10. A novel fiber-packed column for on-line preconcentration and speciation analysis of chromium in drinking water with flame atomic absorption spectrometry.

    PubMed

    Monasterio, Romina P; Altamirano, Jorgelina C; Martínez, Luis D; Wuilloud, Rodolfo G

    2009-02-15

    A novel on-line preconcentration and determination system based on a fiber-packed column was developed for speciation analysis of Cr in drinking water samples prior to its determination by flame atomic absorption spectrometry (FAAS). All variables involved in the development of the preconcentration method including, pH, eluent type, sample and eluent flow rates, interfering effects, etc., were studied in order to achieve the best analytical performance. A preconcentration factor of 32 was obtained for Cr(VI) and Cr(III). The levels of Cr(III) species were calculated by difference of total Cr and Cr(VI) levels. Total Cr was determined after oxidation of Cr(III) to Cr(VI) with hydrogen peroxide. The calibration graph was linear with a correlation coefficient of 0.999 at levels near the detection limit and up to at least 50 microg L(-1). The relative standard deviation (R.S.D.) was 4.3% (C=5 microg L(-1) Cr(VI), n=10, sample volume=25 mL). The limit of detection (LOD) for both Cr(III) and Cr(VI) species was 0.3 microg L(-1). Verification of the accuracy was carried out by the analysis of a standard reference material (NIST SRM 1643e "Trace elements in natural water"). The method was successfully applied to the determination of Cr(III) and Cr(VI) species in drinking water samples.

  11. Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: Analysis of Individual Particles from Marine Boundary Layer over the California Current

    SciTech Connect

    William R. Wiley Environmental Sciences Laboratory, Pacific Northwest National Laboratory; Gilles, Mary K; Hopkins, Rebecca J.; Desyaterik, Yury; Tivanski, Alexei V.; Zaveri, Rahul A.; Berkowitz, Carl M.; Tyliszczak, Tolek; Gilles, Mary K.; Laskin, Alexander

    2008-03-12

    Detailed chemical speciation of the dry residue particles from individual cloud droplets and interstitial aerosol collected during the Marine Stratus Experiment (MASE) was performed using a combination of complementary microanalysis techniques. Techniques include computer controlled scanning electron microscopy with energy dispersed analysis of X-rays (CCSEM/EDX), time-of-flight secondary ionization mass spectrometry (TOF-SIMS), and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Samples were collected at the ground site located in Point Reyes National Seashore, approximately 1 km from the coast. This manuscript focuses on the analysis of individual particles sampled from air masses that originated over the open ocean and then passed through the area of the California current located along the northern California coast. Based on composition, morphology, and chemical bonding information, two externally mixed, distinct classes of sulfur containing particles were identified: chemically modified (aged) sea salt particles and secondary formed sulfate particles. The results indicate substantial heterogeneous replacement of chloride by methanesulfonate (CH3SO3-) and non-sea salt sulfate (nss-SO42-) in sea-salt particles with characteristic ratios of nss-S/Na>0.10 and CH3SO3-/nss-SO42->0.6.

  12. The evolutionary genetics of speciation.

    PubMed Central

    Coyne, J A; Orr, H A

    1998-01-01

    The last decade has brought renewed interest in the genetics of speciation, yielding a number of new models and empirical results. Defining speciation as 'the origin of reproductive isolation between two taxa', we review recent theoretical studies and relevant data, emphasizing the regular patterns seen among genetic analyses. Finally, we point out some important and tractable questions about speciation that have been neglected. PMID:9533126

  13. Guidelines for dynamic data acquisition and analysis

    NASA Technical Reports Server (NTRS)

    Piersol, Allan G.

    1992-01-01

    The recommendations concerning pyroshock data presented in the final draft of a proposed military handbook on Guidelines for Dynamic Data Acquisition and Analysis are reviewed. The structural responses produced by pyroshocks are considered to be one of the most difficult types of dynamic data to accurately measure and analyze.

  14. Guidelines for dynamic data acquisition and analysis

    NASA Technical Reports Server (NTRS)

    Piersol, Allan G.

    1992-01-01

    The recommendations concerning pyroshock data presented in the final draft of a proposed military handbook on Guidelines for Dynamic Data Acquisition and Analysis are reviewed. The structural responses produced by pyroshocks are considered to be one of the most difficult types of dynamic data to accurately measure and analyze.

  15. Guidelines for dynamic data acquisition and analysis

    NASA Astrophysics Data System (ADS)

    Piersol, Allan G.

    1992-10-01

    The recommendations concerning pyroshock data presented in the final draft of a proposed military handbook on Guidelines for Dynamic Data Acquisition and Analysis are reviewed. The structural responses produced by pyroshocks are considered to be one of the most difficult types of dynamic data to accurately measure and analyze.

  16. Arsenic Speciation in Groundwater: Role of Thioanions

    EPA Science Inventory

    The behavior of arsenic in groundwater environments is fundamentally linked to its speciation. Understanding arsenic speciation is important because chemical speciation impacts reactivity, bioavailability, toxicity, and transport and fate processes. In aerobic environments arsen...

  17. Arsenic Speciation in Groundwater: Role of Thioanions

    EPA Science Inventory

    The behavior of arsenic in groundwater environments is fundamentally linked to its speciation. Understanding arsenic speciation is important because chemical speciation impacts reactivity, bioavailability, toxicity, and transport and fate processes. In aerobic environments arsen...

  18. Dynamic Wireless Power Transfer - Grid Impacts Analysis

    SciTech Connect

    Markel, Tony; Meintz, Andrew; Gonder, Jeff

    2015-12-04

    This presentation discusses the current status of analysis of the electricity grid impacts of a dynamic wireless power transfer system deployed to the Atlanta region on select high traffic roadway segments.

  19. Bimolecular dynamics by computer analysis

    SciTech Connect

    Eilbeck, J.C.; Lomdahl, P.S.; Scott, A.C.

    1984-01-01

    As numerical tools (computers and display equipment) become more powerful and the atomic structures of important biological molecules become known, the importance of detailed computation of nonequilibrium biomolecular dynamics increases. In this manuscript we report results from a well developed study of the hydrogen bonded polypeptide crystal acetanilide, a model protein. Directions for future research are suggested. 9 references, 6 figures.

  20. Random Matrix Theory in molecular dynamics analysis.

    PubMed

    Palese, Luigi Leonardo

    2015-01-01

    It is well known that, in some situations, principal component analysis (PCA) carried out on molecular dynamics data results in the appearance of cosine-shaped low index projections. Because this is reminiscent of the results obtained by performing PCA on a multidimensional Brownian dynamics, it has been suggested that short-time protein dynamics is essentially nothing more than a noisy signal. Here we use Random Matrix Theory to analyze a series of short-time molecular dynamics experiments which are specifically designed to be simulations with high cosine content. We use as a model system the protein apoCox17, a mitochondrial copper chaperone. Spectral analysis on correlation matrices allows to easily differentiate random correlations, simply deriving from the finite length of the process, from non-random signals reflecting the intrinsic system properties. Our results clearly show that protein dynamics is not really Brownian also in presence of the cosine-shaped low index projections on principal axes.

  1. SPECIATE--EPA'S DATABASE OF SPECIATED EMISSION PROFILES

    EPA Science Inventory

    SPECIATE is EPA's repository of Total Organic Compound and Particulate Matter speciated profiles for a wide variety of sources. The profiles in this system are provided for air quality dispersion modeling and as a library for source-receptor and source apportionment type models. ...

  2. SPECIATE--EPA'S DATABASE OF SPECIATED EMISSION PROFILES

    EPA Science Inventory

    SPECIATE is EPA's repository of Total Organic Compound and Particulate Matter speciated profiles for a wide variety of sources. The profiles in this system are provided for air quality dispersion modeling and as a library for source-receptor and source apportionment type models. ...

  3. Coupled dynamics analysis of wind energy systems

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.

    1977-01-01

    A qualitative description of all key elements of a complete wind energy system computer analysis code is presented. The analysis system addresses the coupled dynamics characteristics of wind energy systems, including the interactions of the rotor, tower, nacelle, power train, control system, and electrical network. The coupled dynamics are analyzed in both the frequency and time domain to provide the basic motions and loads data required for design, performance verification and operations analysis activities. Elements of the coupled analysis code were used to design and analyze candidate rotor articulation concepts. Fundamental results and conclusions derived from these studies are presented.

  4. Speciation analysis of Sb(III) and Sb(V) in antileishmaniotic drug using Dowex 1 x 4 resin from hydrochloric acid solution.

    PubMed

    Łukaszczyk, L; Zyrnicki, W

    2010-09-05

    A new and simple method for the direct and simultaneous determination of Sb(III) and Sb(V) in meglumine antimoniate, the first-choice drug for leishmaniasis treatment, was developed. Speciation analysis was carried out using the quantitative separation of inorganic trivalent and pentavalent antimony on Dowex 1 x 4 resin from 1.5 mol l(-1) hydrochloric acid solution. The inductively coupled plasma optical emission spectrometry (ICP-OES) was used for determination of antimony. The interfering effects of As, Bi, Cd, Cu, Mn, Pb and Zn were examined and only Bi was found to be a significant interferent. The liberation of Sb(V) and Sb(III) from organoantimonial compounds without changing of oxidation state was carried out by means of 1.5 mol l(-1) hydrochloric acid solution. The spike recovery values obtained for Sb(III) in pharmaceutical sample varied from 92 to 100%. The method was successfully applied for the direct determination of antimony(III) and of antimony(V) in meglumine antimoniate. 2010 Elsevier B.V. All rights reserved.

  5. Speciation analysis of Mn(II)/Mn(VII) using Fe3O4@ionic liquids-β-cyclodextrin polymer magnetic solid phase extraction coupled with ICP-OES.

    PubMed

    Chen, Songqing; Qin, Xingxiu; Gu, Weixi; Zhu, Xiashi

    2016-12-01

    Ionic liquids-β-cyclodextrin polymer (ILs-β-CDCP) was attached on Fe3O4 nanoparticles to prepare magnetic solid phase extraction agent (Fe3O4@ILs-β-CDCP). The properties and morphology of Fe3O4@ILs-β-CDCP were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD), size distribution and magnetic analysis. A new method of magnetic solid phase extraction (MSPE) coupled to ICP-OES for the speciation of Mn(II)/Mn(VII) in water samples was established. The results showed that Mn(VII) and total manganese [Mn(II)+Mn(VII)] were quantitatively extracted after adjusting aqueous sample solution to pH 6.0 and 10.0, respectively. Mn(II) was calculated by subtraction of Mn(VII) from total manganese. Fe3O4@ILs-β-CDCP showed a higher adsorption capacity toward Mn(II) and Mn(VII). Several factors, such as the pH value, extraction temperature and sample volume, were optimized to achieve the best extraction efficiency. Moreover, the adsorption ability of Fe3O4@ILs-β-CDCP would not be significantly lower after reusing of 10 times. The accuracy of the developed method was confirmed by analyzing certified reference materials (GSB 07-1189-2000), and by spiking spring water, city water and lake water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Size exclusion chromatography with evaporative light scattering detection as a method for speciation analysis of polydimethylsiloxanes. III. Identification and determination of dimeticone and simeticone in pharmaceutical formulations.

    PubMed

    Mojsiewicz-Pieńkowska, Krystyna

    2012-01-25

    The pharmaceutical industry is one of the more important sectors for the use of polydimethylsiloxanes (PDMS), which belong to the organosilicon polymers. In drugs for internal use, they are used as an active pharmaceutical ingredient (API) called dimeticone or simeticone. Due to their specific chemical nature, PDMS can have different degrees of polymerization, which determine the molecular weight and viscosity. The Pharmacopoeial monographs for dimeticone and simeticone, only give the permitted polymerization and viscosity range. It is, however, essential to know also the degree of polymerization or the specific molecular weight of PDMS that are present in pharmaceutical formulations. In the literature there is information about the impact of particle size, and thus molecular weight, on the toxicity, absorption and migration in living organisms. This study focused on the use of a developed method - the exclusion chromatography with evaporative light scattering detector (SEC-ELSD) - for identification and determination of dimeticone and simeticone in various pharmaceutical formulations. The method had a high degree of specificity and was suitable for speciation analysis of these polymers. So far the developed method has not been used in the control of medicinal products containing dimeticone or simeticone.

  7. Correction of species transformations in the analysis of Cr(VI) in solid environmental samples using speciated isotope dilution mass spectrometry

    PubMed

    Huo; Kingston

    2000-10-15

    Speciation of Cr(VI) in solid environmental samples is challenging because of the transformations between Cr(VI) and Cr(III). EPA method 3060A completely extracts Cr(VI) in a hot alkaline solution and preserves the solublized Cr(VI). This procedure, however, can oxidize Cr(III) in some chemical forms. On the other hand, the reverse transformation may occur during neutralization and acidification following the extraction step. We developed a method that is capable of monitoring and correcting for such bidirectional species transformations to determine Cr(VI) in solid samples. In this method, we spike a sample with a 53Cr(VI) spike (enriched in 53Cr) and a isoCr(III) spike (enriched in 50Cr). The large quantity of isoCr(III) in an easily oxidizable form competes with sample Cr(III) in the oxidization, reducing the method-induced oxidation of sample Cr(III). This method also corrects for the reduction of Cr(VI). The theory is presented and is evaluated experimentally. The analysis of chromite ore processing residue, fly ash, and standard reference material SRM 1645 showed that the oxidation of sample Cr(III) could cause positive biases as high as 163% if no correction is performed.

  8. Hard X-Ray Spectro Microprobe Analysis of Inhomogeneous Solids: A Case Study. Element Distribution and Speciation in Selected Iron Meteorite

    SciTech Connect

    Cavell, R.G.; Feng, R.; Barnes, E.M.; Cavell, P.A.; McCready, A.J.; Webb, M.A.

    2007-06-08

    The hard X-ray microprobe provides an effective methodology for the non-destructive analysis of inhomogeneous materials. Application of X-ray absorption/fluroescence spectroscopy techniques (XANES and EXAFS) permits the speciation of the elements and yields information about the local structural environment. Microfocussed, monochromatic, tunable X-rays allows examination of small areas of micrometer dimensions with spectroscopic procedures. Typically the materials which are presented are thick and cannot be altered for the experiment. This condition introduces difficulties which may compromise the results. Herein we discuss those difficulties and show that the system can yield reliable results in spite of the compromises. Some results are presented on the two iron meteorites we have examined. These specimens are representative of highly inhomogeneous materials and illustrate the difficulties encountered with compositional variations which may occur at sub-millimeter dimensions and also illustrate the difficulties presented by the need to analyze components present at ppm concentration levels in a concentrated matrix. In these particular samples the major constituent is Fe which ranges from 90% to 70%, balanced by Ni which ranges from 10% to 30%. The critical diagnostic trace elements Ga and Ge which must also be analyzed are present at the 80 and 340 ppm level respectively. These diagnostic elements have been shown by EXAFS to be substitutionally placed in the matrix of the major element species in these meteorite samples.

  9. Arsenic speciation analysis in mono-varietal wines by on-line ionic liquid-based dispersive liquid-liquid microextraction.

    PubMed

    Escudero, Leticia B; Martinis, Estefanía M; Olsina, Roberto A; Wuilloud, Rodolfo G

    2013-05-01

    A highly efficient separation and pre-concentration method for arsenic species determination, based on ionic liquid (IL) dispersive microextraction technique implemented in a flow analysis system, is proposed. Highly selective separation of arsenite species [As(III)] was achieved by chelation with sodium diethyldithiocarbamate (DDTC) followed by dispersion with 40 mg of 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF(6)]) IL. Analyte extraction, retention and separation of IL phase were achieved with a packed microcolumn and As(III) was determined in eluent solution by electrothermal atomic absorption spectrometry (ETAAS). Concentration of As(V) was deduced by the difference between total inorganic arsenic and As(III). Thus, determination of total arsenic was performed by previous degradation of organo-arsenic species, followed by a reduction. Under optimal conditions, As(III) extraction efficiency was 100% and a sensitivity enhancement factor of 46 was obtained with only 4.0 ml of sample The method was successfully applied for arsenic speciation studies in mono-varietal wines.

  10. Session 6: Dynamic Modeling and Systems Analysis

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey; Chapman, Jeffryes; May, Ryan

    2013-01-01

    These presentations cover some of the ongoing work in dynamic modeling and dynamic systems analysis. The first presentation discusses dynamic systems analysis and how to integrate dynamic performance information into the systems analysis. The ability to evaluate the dynamic performance of an engine design may allow tradeoffs between the dynamic performance and operability of a design resulting in a more efficient engine design. The second presentation discusses the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a Simulation system with a library containing the basic building blocks that can be used to create dynamic Thermodynamic Systems. Some of the key features include Turbo machinery components, such as turbines, compressors, etc., and basic control system blocks. T-MAT is written in the Matlab-Simulink environment and is open source software. The third presentation focuses on getting additional performance from the engine by allowing the limit regulators only to be active when a limit is danger of being violated. Typical aircraft engine control architecture is based on MINMAX scheme, which is designed to keep engine operating within prescribed mechanical/operational safety limits. Using a conditionally active min-max limit regulator scheme, additional performance can be gained by disabling non-relevant limit regulators

  11. Mathematical analysis of vortex dynamics

    NASA Astrophysics Data System (ADS)

    Caflisch, Russel E.

    This review paper discusses the mathematical theory of vortex dynamics for incompressible, inviscid flow in two and three dimensions. The surveyed results include existence and uniqueness of time-dependent solutions, instability and singularity formation, convergence of numerical methods, and existence and stability of steady states. A simple integral formulation for the evolution of a three dimensional vortex sheet and a variational principle for the Batchelor flow problem are presented.

  12. STEP Tether Dynamics Preliminary Analysis

    NASA Technical Reports Server (NTRS)

    Glaese, John R.

    2000-01-01

    The General Tethered Object Simulation System (GTOSS) has been successfully converted to the PC environment. GTOSS has been run under Microsoft Windows 95, 98 and NT4.0 with no problems noted. Adaptation to the PC environment and definition of the 3 three body configuration required resizing some of the GTOSS internal data arrays. To allow studies of the tether dynamics accompanying electrodynamic thrust, a tether current flow model has also been developed for GTOSS. This model includes effects due to the earth's magnetic field and ionosphere, tether conductivity, temperature, motion, shape and available power. Sample cases have been defined for a proposed STEP-AIRSEDS (Space Transfer using Electrodynamic Propulsion-The Michigan Technic Corporation proposed tether missions for commercial applications) three body configuration. This required definition of a 6th power scenario for GTOSS. This power scenario allows a user to specify whether orbit raising or orbit lowering is to be performed by selecting the number of the tether. Orbit raising and orbit lowering sample cases have been run successfully. Results from these runs have been included in this report. Results have only been generated so far for a three body configuration. Only point end masses have been represented. No attitude dynamics have been included. Initial results suggest that tether current can have significant and detrimental effects on tether dynamics and provisions will have to be made for control of it. This control will have to be considered in connection with desired target orbits for electrodynamic thrusting, as well as end body attitude control, momentum management of proposed control moment gyros, solar array pointing. All of these items will interact and thus, any system simulation will have to have each of these effects modeled in sufficient detail to display these interactions.

  13. Predictive structural dynamic network analysis.

    PubMed

    Chen, Rong; Herskovits, Edward H

    2015-04-30

    Classifying individuals based on magnetic resonance data is an important task in neuroscience. Existing brain network-based methods to classify subjects analyze data from a cross-sectional study and these methods cannot classify subjects based on longitudinal data. We propose a network-based predictive modeling method to classify subjects based on longitudinal magnetic resonance data. Our method generates a dynamic Bayesian network model for each group which represents complex spatiotemporal interactions among brain regions, and then calculates a score representing that subject's deviation from expected network patterns. This network-derived score, along with other candidate predictors, are used to construct predictive models. We validated the proposed method based on simulated data and the Alzheimer's Disease Neuroimaging Initiative study. For the Alzheimer's Disease Neuroimaging Initiative study, we built a predictive model based on the baseline biomarker characterizing the baseline state and the network-based score which was constructed based on the state transition probability matrix. We found that this combined model achieved 0.86 accuracy, 0.85 sensitivity, and 0.87 specificity. For the Alzheimer's Disease Neuroimaging Initiative study, the model based on the baseline biomarkers achieved 0.77 accuracy. The accuracy of our model is significantly better than the model based on the baseline biomarkers (p-value=0.002). We have presented a method to classify subjects based on structural dynamic network model based scores. This method is of great importance to distinguish subjects based on structural network dynamics and the understanding of the network architecture of brain processes and disorders. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. The drivers of tropical speciation.

    PubMed

    Smith, Brian Tilston; McCormack, John E; Cuervo, Andrés M; Hickerson, Michael J; Aleixo, Alexandre; Cadena, Carlos Daniel; Pérez-Emán, Jorge; Burney, Curtis W; Xie, Xiaoou; Harvey, Michael G; Faircloth, Brant C; Glenn, Travis C; Derryberry, Elizabeth P; Prejean, Jesse; Fields, Samantha; Brumfield, Robb T

    2014-11-20

    Since the recognition that allopatric speciation can be induced by large-scale reconfigurations of the landscape that isolate formerly continuous populations, such as the separation of continents by plate tectonics, the uplift of mountains or the formation of large rivers, landscape change has been viewed as a primary driver of biological diversification. This process is referred to in biogeography as vicariance. In the most species-rich region of the world, the Neotropics, the sundering of populations associated with the Andean uplift is ascribed this principal role in speciation. An alternative model posits that rather than being directly linked to landscape change, allopatric speciation is initiated to a greater extent by dispersal events, with the principal drivers of speciation being organism-specific abilities to persist and disperse in the landscape. Landscape change is not a necessity for speciation in this model. Here we show that spatial and temporal patterns of genetic differentiation in Neotropical birds are highly discordant across lineages and are not reconcilable with a model linking speciation solely to landscape change. Instead, the strongest predictors of speciation are the amount of time a lineage has persisted in the landscape and the ability of birds to move through the landscape matrix. These results, augmented by the observation that most species-level diversity originated after episodes of major Andean uplift in the Neogene period, suggest that dispersal and differentiation on a matrix previously shaped by large-scale landscape events was a major driver of avian speciation in lowland Neotropical rainforests.

  15. Lead Speciation in Microorganisms.

    PubMed

    Stewart, Theodora J

    2017-04-10

    The biogeochemical cycles of lead (Pb) have been largely affected by anthropogenic activities as a result of its high natural abundance and use over the centuries [1]. At sites more strongly impacted by urbanization [2] and mining [3], Pb is found at high nano to low micromolar concentrations in surface waters, and can be significantly higher in soil and sediment [4]. Microorganisms are found everywhere and their responses to Pb exposure can range from resistant to highly sensitive [5, 6]. These varying levels of toxicity can be attributed to the cellular handling of Pb, making it important to understand the role of intracellular Pb speciation for more accurate toxicity predictions.

  16. Nonlinear Dynamical Analysis of Fibrillation

    NASA Astrophysics Data System (ADS)

    Kerin, John A.; Sporrer, Justin M.; Egolf, David A.

    2013-03-01

    The development of spatiotemporal chaotic behavior in heart tissue, termed fibrillation, is a devastating, life-threatening condition. The chaotic behavior of electrochemical signals, in the form of spiral waves, causes the muscles of the heart to contract in an incoherent manner, hindering the heart's ability to pump blood. We have applied the mathematical tools of nonlinear dynamics to large-scale simulations of a model of fibrillating heart tissue to uncover the dynamical modes driving this chaos. By studying the evolution of Lyapunov vectors and exponents over short times, we have found that the fibrillating tissue is sensitive to electrical perturbations only in narrow regions immediately in front of the leading edges of spiral waves, especially when these waves collide, break apart, or hit the edges of the tissue sample. Using this knowledge, we have applied small stimuli to areas of varying sensitivity. By studying the evolution of the effects of these perturbations, we have made progress toward controlling the electrochemical patterns associated with heart fibrillation. This work was supported by the U.S. National Science Foundation (DMR-0094178) and Research Corporation.

  17. Contextual analysis framework for bursty dynamics

    NASA Astrophysics Data System (ADS)

    Jo, Hang-Hyun; Pan, Raj Kumar; Perotti, Juan I.; Kaski, Kimmo

    2013-06-01

    To understand the origin of bursty dynamics in natural and social processes we provide a general analysis framework in which the temporal process is decomposed into subprocesses and then the bursts in subprocesses, called contextual bursts, are combined to collective bursts in the original process. For the combination of subprocesses, it is required to consider the distribution of different contexts over the original process. Based on minimal assumptions for interevent time statistics, we present a theoretical analysis for the relationship between contextual and collective interevent time distributions. Our analysis framework helps to exploit contextual information available in decomposable bursty dynamics.

  18. Sulfur speciation in natural hydrothermal waters, Iceland

    NASA Astrophysics Data System (ADS)

    Kaasalainen, Hanna; Stefánsson, Andri

    2011-05-01

    The speciation of aqueous dissolved sulfur was determined in hydrothermal waters in Iceland. The waters sampled included hot springs, acid-sulfate pools and mud pots, sub-boiling well discharges and two-phase wells. The water temperatures ranged from 4 to 210 °C, the pH T was between 2.20 and 9.30 at the discharge temperature and the SO 4 and Cl concentrations were 0.020-52.7 and <0.01-10.0 mmol kg -1, respectively. The analyses were carried out on-site within ˜10 min of sampling using ion chromatography (IC) for sulfate (SO 42-), thiosulfate (S 2O 32-) and polythionates (S xO 62-) and titration and/or colorimetry for total dissolved sulfide (S 2-). Sulfite (SO 32-) could also be determined in a few cases using IC. Alternatively, for few samples in remote locations the sulfur oxyanions were stabilized on a resin on site following elution and analysis by IC in the laboratory. Dissolved sulfate and with few exceptions also S 2- were detected in all samples with concentrations of 0.02-52.7 mmol kg -1 and <1-4100 μmol kg -1, respectively. Thiosulfate was detected in 49 samples of the 73 analyzed with concentrations in the range of <1-394 μmol kg -1 (S-equivalents). Sulfite was detected in few samples with concentrations in the range of <1-3 μmol kg -1. Thiosulfate and SO 32- were not detected in <100 °C well waters and S 2O 32- was observed only at low concentrations (<1-8 μmol kg -1) in ˜200 °C well waters. In alkaline and neutral pH hot springs, S 2O 32- was present in significant concentrations sometimes corresponding to up to 23% of total dissolved sulfur (S TOT). In steam-heated acid-sulfate waters, S 2O 32- was not a significant sulfur species. The results demonstrate that S 2O 32- and SO 32- do not occur in the deeper parts of <150 °C hydrothermal systems and only in trace concentrations in ˜200-300 °C systems. Upon ascent to the surface and mixing with oxygenated ground and surface waters and/or dissolution of atmospheric O 2, S 2- is degassed and

  19. Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: Analysis of Individual Particles from the Marine Boundary Layer Over the California Current

    SciTech Connect

    Hopkins, Rebecca J; Desyaterik, Yury; Tivanski, Alexei V; Zaveri, Rahul A; Berkowitz, Carl M; Tyliszczak, T; Gilles, Marry K; Laskin, Alexander

    2008-02-27

    Detailed chemical speciation of the dry residue particles from individual cloud droplets and interstitial aerosol collected during the Marine Stratus Experiment (MASE) was performed using a complementary combination of microanalysis techniques. Techniques include computer controlled scanning electron microscopy with energy dispersed analysis of X-rays (CCSEM/EDX), time-of-flight secondary ionization mass spectrometry (TOFSIMS), and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Samples were collected at the ground site located in Point Reyes National Seashore, approximately 1 km from the coast. This manuscript focuses on the analysis of individual particles sampled from an air mass that originated over the open ocean and then passed through the area of the California current located along the northern California coast. Based on composition, morphology, and chemical bonding information, two externally mixed, distinct classes of sulfur containing particles were identified: chemically modified (aged) sea salt particles and secondary formed sulfate particles. The results indicate substantial heterogeneous replacement of chloride by methanesulfonate (CH3SO3-) and non-sea salt sulfate (nss-SO42-) in sea-salt particles with the characteristic ratios of CH3SO3-/nss-SO42-> 0.6. Although this value seems too high for a mid-latitude site, our model calculations suggest that high CH3SO3-/nss-SO42- ratios are expected during the early stages of dimethyl sulfide (DMS) oxidation when CH3SO3H forms more rapidly than H2SO4.

  20. Visual Analysis of Dynamic Data Streams

    SciTech Connect

    Chin, George; Singhal, Mudita; Nakamura, Grant C.; Gurumoorthi, Vidhya; Freeman-Cadoret, Natalie A.

    2009-09-01

    For scientific data visualizations, real-time data streams present many interesting challenges when compared to static data. Real-time data are dynamic, transient, high-volume, and temporal. Effective visualizations need to be able to accommodate dynamic data behavior as well as abstract and present the data in ways that make sense to and are usable by humans. The Visual Content Analysis of Real-Time Data Streams project at the Pacific Northwest National Laboratory is researching and prototyping dynamic visualization techniques and tools to help facilitate human understanding and comprehension of high-volume, real-time data. The general strategy of the project is to develop and evolve visual contexts that will organize and orient complex dynamic data in conceptual and perceptive views. The goal is to allow users to quickly grasp dynamic data in forms that are intuitive and natural without requiring intensive training in the use of specific visualization or analysis tools and methods. Thus far, the project has prototyped four different visualization prototypes that represents and convey dynamic data through human-recognizable contexts and paradigms such as hierarchies, relationships, time, and geography. We describe the design considerations and unique features of these dynamic visualization prototypes as well as our findings in the exploration and evaluation of their use.

  1. Application of chemometric analysis and self Organizing Map-Artificial Neural Network as source receptor modeling for metal speciation in river sediment.

    PubMed

    Pandey, Mayank; Pandey, Ashutosh Kumar; Mishra, Ashutosh; Tripathi, B D

    2015-09-01

    Present study deals with the river Ganga water quality and its impact on metal speciation in its sediments. Concentration of physico-chemical parameters was highest in summer season followed by winter and lowest in rainy season. Metal speciation study in river sediments revealed that exchangeable, reducible and oxidizable fractions were dominant in all the studied metals (Cr, Ni, Cu, Zn, Cd, Pb) except Mn and Fe. High pollution load index (1.64-3.89) recommends urgent need of mitigation measures. Self-organizing Map-Artificial Neural Network (SOM-ANN) was applied to the data set for the prediction of major point sources of pollution in the river Ganga.

  2. Microscale imaging and identification of Fe speciation and distribution during fluid-mineral reactions under highly reducing conditions.

    PubMed

    Mayhew, L E; Webb, S M; Templeton, A S

    2011-05-15

    The oxidation state, speciation, and distribution of Fe are critical determinants of Fe reactivity in natural and engineered environments. However, it is challenging to follow dynamic changes in Fe speciation in environmental systems during progressive fluid-mineral interactions. Two common geological and aquifer materials-basalt and Fe(III) oxides-were incubated with saline fluids at 55 °C under highly reducing conditions maintained by the presence of Fe(0). We tracked changes in Fe speciation after 48 h (incipient water-rock reaction) and 10 months (extensive water-rock interaction) using synchrotron-radiation μXRF maps collected at multiple energies (ME) within the Fe K-edge. Immediate PCA analysis of the ME maps was used to optimize μXANES analyses; in turn, refitting the ME maps with end-member XANES spectra enabled us to detect and spatially resolve the entire variety of Fe-phases present in the system. After 48 h, we successfully identified and mapped the major Fe-bearing components of our samples (Fe(III) oxides, basalt, and rare olivine), as well as small quantities of incipient brucite associated with olivine. After 10 months, the Fe(III)-oxides remained stable in the presence of Fe(0), whereas significant alteration of basalt to minnesotaite and chlinochlore had occurred, providing new insights into heterogeneous Fe speciation in complex geological media under highly reducing conditions.

  3. SPECIATE 4.0: SPECIATION DATABASE DEVELOPMENT DOCUMENTATION--FINAL REPORT

    EPA Science Inventory

    SPECIATE is the U.S. EPA's repository of total organic compounds (TOC) and particulate matter (PM) speciation profiles of air pollution sources. This report documents how EPA developed the SPECIATE 4.0 database that replaces the prior version, SPECIATE 3.2. SPECIATE 4.0 includes ...

  4. SPECIATE 4.0: SPECIATION DATABASE DEVELOPMENT DOCUMENTATION--FINAL REPORT

    EPA Science Inventory

    SPECIATE is the U.S. EPA's repository of total organic compounds (TOC) and particulate matter (PM) speciation profiles of air pollution sources. This report documents how EPA developed the SPECIATE 4.0 database that replaces the prior version, SPECIATE 3.2. SPECIATE 4.0 includes ...

  5. Analytical signal analysis of strange nonchaotic dynamics.

    PubMed

    Gupta, Kopal; Prasad, Awadhesh; Singh, Harinder P; Ramaswamy, Ramakrishna

    2008-04-01

    We apply an analytical signal analysis to strange nonchaotic dynamics. Through this technique it is possible to obtain the spectrum of instantaneous intrinsic mode frequencies that are present in a given signal. We find that the second-mode frequency and its variance are good order parameters for dynamical transitions from quasiperiodic tori to strange nonchaotic attractors (SNAs) and from SNAs to chaotic attractors. Phase fluctuation analysis shows that SNAs and chaotic attractors behave identically within short time windows as a consequence of local instabilities in the dynamics. In longer time windows, however, the globally stable character of SNAs becomes apparent. This methodology can be of great utility in the analysis of experimental time series, and representative applications are made to signals obtained from Rössler and Duffing oscillators.

  6. Mechanisms of speciation and faunal enrichment in Atlantic parrotfishes.

    PubMed

    Robertson, D Ross; Karg, Frances; Leao de Moura, Rodrigo; Victor, Benjamin C; Bernardi, Giacomo

    2006-09-01

    Relationships based on mtDNA and nDNA sequences were used to assess effects of two major geographic barriers (the >30 myo Atlantic ocean and the approximately 11 myo Amazon-Orinoco outflow) on speciation among Atlantic parrotfishes (Sparisoma and Nicholsina). Allopatric distributions of sister taxa implicate isolating actions of both barriers in all recent speciation in these fishes, with no clear indications that any speciation resulted from other mechanisms. Molecular clock estimates of the timing of lineage splits indicate that both barriers acted by limiting dispersal well after they formed, although the Amazon barrier also may have been a vicariance agent. Fluctuations in sealevel, climate, and ocean-current dynamics over the past approximately 10 my likely produced marked variation in the effectiveness of both barriers, but particularly the Amazon barrier, allowing intermittent dispersal leading to establishment and allopatric speciation. A dynamic Amazon barrier represents a major engine of West Atlantic faunal enrichment that has repeatedly facilitated bidirectional dispersal, allopatric speciation, and remixing of the Caribbean and Brazilian faunas.

  7. Automated dynamic hollow fiber liquid-liquid-liquid microextraction combined with capillary electrophoresis for speciation of mercury in biological and environmental samples.

    PubMed

    Li, Pingjing; He, Man; Chen, Beibei; Hu, Bin

    2015-10-09

    A simple home-made automatic dynamic hollow fiber based liquid-liquid-liquid microextraction (AD-HF-LLLME) device was designed and constructed for the simultaneous extraction of organomercury and inorganic mercury species with the assistant of a programmable flow injection analyzer. With 18-crown-6 as the complexing reagent, mercury species including methyl-, ethyl-, phenyl- and inorganic mercury were extracted into the organic phase (chlorobenzene), and then back-extracted into the acceptor phase of 0.1% (m/v) 3-mercapto-1-propanesulfonic acid (MPS) aqueous solution. Compared with automatic static (AS)-HF-LLLME system, the extraction equilibrium of target mercury species was obtained in shorter time with higher extraction efficiency in AD-HF-LLLME system. Based on it, a new method of AD-HF-LLLME coupled with large volume sample stacking (LVSS)-capillary electrophoresis (CE)/UV detection was developed for the simultaneous analysis of methyl-, phenyl- and inorganic mercury species in biological samples and environmental water. Under the optimized conditions, AD-HF-LLLME provided high enrichment factors (EFs) of 149-253-fold within relatively short extraction equilibrium time (25min) and good precision with RSD between 3.8 and 8.1%. By combining AD-HF-LLLME with LVSS-CE/UV, EFs were magnified up to 2195-fold and the limits of detection (at S/N=3) for target mercury species were improved to be sub ppb level. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Ecological speciation in Gambusia fishes.

    PubMed

    Langerhans, R Brian; Gifford, Matthew E; Joseph, Everton O

    2007-09-01

    Although theory indicates that natural selection can facilitate speciation as a by-product, demonstrating ongoing speciation via this by-product mechanism in nature has proven difficult. We examined morphological, molecular, and behavioral data to investigate ecology's role in incipient speciation for a post-Pleistocene radiation of Bahamas mosquitofish (Gambusia hubbsi) inhabiting blue holes. We show that adaptation to divergent predator regimes is driving ecological speciation as a by-product. Divergence in body shape, coupled with assortative mating for body shape, produces reproductive isolation that is twice as strong between populations inhabiting different predator regimes than between populations that evolved in similar ecological environments. Gathering analogous data on reproductive isolation at the interspecific level in the genus, we find that this mechanism of speciation may have been historically prevalent in Gambusia. These results suggest that speciation in nature can result as a by-product of divergence in ecologically important traits, producing interspecific patterns that persist long after speciation events have completed.

  9. Dynamic Event Tree Analysis Through RAVEN

    SciTech Connect

    A. Alfonsi; C. Rabiti; D. Mandelli; J. Cogliati; R. A. Kinoshita; A. Naviglio

    2013-09-01

    Conventional Event-Tree (ET) based methodologies are extensively used as tools to perform reliability and safety assessment of complex and critical engineering systems. One of the disadvantages of these methods is that timing/sequencing of events and system dynamics is not explicitly accounted for in the analysis. In order to overcome these limitations several techniques, also know as Dynamic Probabilistic Risk Assessment (D-PRA), have been developed. Monte-Carlo (MC) and Dynamic Event Tree (DET) are two of the most widely used D-PRA methodologies to perform safety assessment of Nuclear Power Plants (NPP). In the past two years, the Idaho National Laboratory (INL) has developed its own tool to perform Dynamic PRA: RAVEN (Reactor Analysis and Virtual control ENvironment). RAVEN has been designed in a high modular and pluggable way in order to enable easy integration of different programming languages (i.e., C++, Python) and coupling with other application including the ones based on the MOOSE framework, developed by INL as well. RAVEN performs two main tasks: 1) control logic driver for the new Thermo-Hydraulic code RELAP-7 and 2) post-processing tool. In the first task, RAVEN acts as a deterministic controller in which the set of control logic laws (user defined) monitors the RELAP-7 simulation and controls the activation of specific systems. Moreover, RAVEN also models stochastic events, such as components failures, and performs uncertainty quantification. Such stochastic modeling is employed by using both MC and DET algorithms. In the second task, RAVEN processes the large amount of data generated by RELAP-7 using data-mining based algorithms. This paper focuses on the first task and shows how it is possible to perform the analysis of dynamic stochastic systems using the newly developed RAVEN DET capability. As an example, the Dynamic PRA analysis, using Dynamic Event Tree, of a simplified pressurized water reactor for a Station Black-Out scenario is presented.

  10. Application Analysis and Decision with Dynamic Analysis

    DTIC Science & Technology

    2014-12-01

    debugging tool, “ adb ”. The tool, adb , is used several times to interact with the mobile VM, by capturing the screenshot, sending SMS messages, executing...and logcat to watch log files. Analysis is ready to begin in earnest. The application is installed on the phone and then launched, all via adb

  11. Structural Dynamics and Data Analysis

    NASA Technical Reports Server (NTRS)

    Luthman, Briana L.

    2013-01-01

    This project consists of two parts, the first will be the post-flight analysis of data from a Delta IV launch vehicle, and the second will be a Finite Element Analysis of a CubeSat. Shock and vibration data was collected on WGS-5 (Wideband Global SATCOM- 5) which was launched on a Delta IV launch vehicle. Using CAM (CAlculation with Matrices) software, the data is to be plotted into Time History, Shock Response Spectrum, and SPL (Sound Pressure Level) curves. In this format the data is to be reviewed and compared to flight instrumentation data from previous flights of the same launch vehicle. This is done to ensure the current mission environments, such as shock, random vibration, and acoustics, are not out of family with existing flight experience. In family means the peaks on the SRS curve for WGS-5 are similar to the peaks from the previous flights and there are no major outliers. The curves from the data will then be compiled into a useful format so that is can be peer reviewed then presented before an engineering review board if required. Also, the reviewed data will be uploaded to the Engineering Review Board Information System (ERBIS) to archive. The second part of this project is conducting Finite Element Analysis of a CubeSat. In 2010, Merritt Island High School partnered with NASA to design, build and launch a CubeSat. The team is now called StangSat in honor of their mascot, the mustang. Over the past few years, the StangSat team has built a satellite and has now been manifested for flight on a SpaceX Falcon 9 launch in 2014. To prepare for the final launch, a test flight was conducted in Mojave, California. StangSat was launched on a Prospector 18D, a high altitude rocket made by Garvey Spacecraft Corporation, along with their sister satellite CP9 built by California Polytechnic University. However, StangSat was damaged during an off nominal landing and this project will give beneficial insights into what loads the CubeSat experienced during the crash

  12. Speciation analysis of arsenic in prenatal and children's dietary supplements using microwave-enhanced extraction and ion chromatography-inductively coupled plasma mass spectrometry.

    PubMed

    Wolle, Mesay M; Rahman, G M Mizanur; Kingston, H M Skip; Pamuku, Matt

    2014-03-25

    A study was conducted to develop a microwave-enhanced extraction method for the determination of arsenic species in prenatal and children's dietary supplements prepared from plant materials. The method was optimized by evaluating the efficiency of various solutions previously used to extract arsenic from the types of plant materials used in the dietary supplement formulations. A multivitamin standard reference material (NIST SRM 3280) and a prenatal supplement sample were analyzed in the method optimization. The identified optimum conditions were 0.25 g of sample, 5 mL of 0.3 mol L(-1) orthophosphoric acid (H3PO4) and microwave heating at 90 °C for 30 min. The extracted arsenic was speciated by cation exchange ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS). The method detection limit (MDL) for the arsenic species was in the range 2-8 ng g(-1). Ten widely consumed prenatal and children's dietary supplements were analyzed using the optimized protocol. The supplements were found to have total arsenic in the concentration range 59-531 ng g(-1). The extraction procedure recovered 61-92% of the arsenic from the supplements. All the supplementary products were found to contain arsenite (As(3+)) and dimethylarsinic acid (DMA). Arsenate (As(5+)) was found in two of the supplements, and an unknown specie of arsenic was detected in one product. The results of the analysis were validated using mass balance by comparing the sum of the extracted and non-extracted arsenic with the total concentration of the element in the corresponding samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Assessment of accuracy and precision in speciation analysis by competitive ligand equilibration-cathodic stripping voltammetry (CLE-CSV) and application to Antarctic samples.

    PubMed

    Monticelli, Damiano; Dossi, Carlo; Castelletti, Alessio

    2010-08-24

    The analytical performances of Competitive Ligand Equilibration with Cathodic Stripping Voltammetric detection of the labile fraction (CLE-CSV) were assessed. This speciation method enables the concentration of natural ligand(s) and their conditional stability constants for the complexation of the investigated metal to be determined through thermodynamic considerations. Literature data were discussed and general trends in the precision of the determined parameters identified: ligand concentrations were affected, on average, by a 10% relative percentage standard deviation (RSD%), whereas conditional stability constants showed much lower precision, with an average RSD% of 50%. New experimental data were collected to obtain a complete assessment of accuracy and precision attainable for the determination of strong ligands at the ultra trace level, enabling the whole protocol to be evaluated. Firstly, the side reaction coefficient alpha for the formation of the complex between the added ligand and the investigated metal (alpha(CuL)) was determined. The method was subsequently applied to the analysis of solution containing ligand at trace levels (5-50 nM) with known complexing characteristics. Copper was used as the model metal ion and ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) as the model ligands. Results evidenced that the CLE-CSV protocol is not affected by systematic errors in the determination of both ligand concentration and the conditional stability constants. Good precision is obtained for ligand concentrations, with an average relative standard deviation (RSD%) of 5%; an average RSD% of 23% was calculated for the conditional stability constants. Including the contribution of the uncertainty in the value of alpha(CuL) in the evaluation of the uncertainty in the latter parameter increased the RSD% up to 40%. The CLE-CSV protocol was subsequently applied to the detection of strong ligands in water samples collected in

  14. Advanced oxidation using Fe(3)O(4) magnetic nanoparticles and its application in mercury speciation analysis by high performance liquid chromatography-cold vapor generation atomic fluorescence spectrometry.

    PubMed

    Ai, Xi; Wang, Yu; Hou, Xiandeng; Yang, Lu; Zheng, Chengbin; Wu, Li

    2013-06-21

    A novel, green and efficient post-column oxidation method using Fe(3)O(4) magnetic nanoparticles (MNPs) was developed to on-line convert hydride generation/cold vapor generation (HG/CV) inactive species to their active species without microwave/UV irradiation. It was applied to high performance liquid chromatography HG/CV atomic fluorescence spectrometry (HPLC-HG/CV-AFS) to enable sensitive speciation analysis of both HG/CV inactive and active species. Inorganic mercury (Hg(2+)), methylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) were selected as model compounds to validate the methodology. Separation of these mercury species was accomplished on a RP-C18 column with a mixture of acetonitrile and water (10 : 90) at pH 6.8 containing 0.12% (m/v) L-cysteine as the mobile phase. In the presence of 0.6% (v/v) H(2)O(2), on-line conversion of the organomercury species eluted from the HPLC column to Hg(2+) was obtained using the advanced oxidation method at pH 2.0. Optimum conditions for the separation, oxidation and cold vapor generation were carefully investigated. The limits of detection (LODs) were 0.7, 1.1, 0.8 and 0.9 μg L(-1) (as Hg) for Hg(2+), MeHg, EtHg and PhHg, respectively, corresponding to 14, 22, 16 and 18 pg absolute detection limits for Hg(2+), MeHg, EtHg and PhHg by using a 20 μL sample loop, which are comparable to or better than those previously reported. National Research Council Canada DORM-2 fish muscle tissue and several real water samples were analyzed to validate the accuracy of the proposed method.

  15. Dynamical analysis of tachyonic chameleon

    NASA Astrophysics Data System (ADS)

    Banijamali, Ali; Solbi, Milad

    2017-08-01

    In the present paper we investigate tachyonic chameleon scalar field and present the phase space analysis for four different combinations of the tachyonic potential V(φ ) and the coupling function f(φ ) of the chameleon field with matter. We find some stable solution in which accelerated expansion of the universe is satisfied. In one case where both f(φ ) and V(φ ) are exponential a scaling attractor was found that can give rise to the late-time acceleration of the universe and alleviate the coincidence problem.

  16. Chronic speciation in periodical cicadas.

    PubMed

    Ritchie, M G.

    2001-02-01

    Allochronic speciation and reproductive character displacement are two intuitively attractive models of speciation. The first proposes that changes in the timing of life cycles produce new species, whereas the second suggests that speciation is due to the exaggeration of sexual isolation in sympatric populations. Clear examples of either process in nature remain elusive, despite some extensive searches. Two recent studies of mtDNA markers and behaviour of periodical cicadas in North America have identified a new species of cicada that seems to provide good evidence for the involvement of both processes in its origin.

  17. Chemical Speciation Analysis of Sports Drinks by Acid-Base Titrimetry and Ion Chromatography: A Challenging Beverage Formulation Project

    ERIC Educational Resources Information Center

    Drossman, Howard

    2007-01-01

    Students have standardized a sodium hydroxide solution and analyzed commercially available sports drinks by titrimetric analysis of the triprotic citric acid, dihydrogen phosphate, and dihydrogen citrate and by ion chromatography for chloride, total phosphate and citrate. These experiments are interesting examples of analyzing real-world food and…

  18. Chemical Speciation Analysis of Sports Drinks by Acid-Base Titrimetry and Ion Chromatography: A Challenging Beverage Formulation Project

    ERIC Educational Resources Information Center

    Drossman, Howard

    2007-01-01

    Students have standardized a sodium hydroxide solution and analyzed commercially available sports drinks by titrimetric analysis of the triprotic citric acid, dihydrogen phosphate, and dihydrogen citrate and by ion chromatography for chloride, total phosphate and citrate. These experiments are interesting examples of analyzing real-world food and…

  19. Progress in understanding uranium(IV) speciation and dynamics in biologically reduced sediments: Research at molecular to centimeter scales by the SLAC SFA program

    NASA Astrophysics Data System (ADS)

    Bargar, J.; Williams, K. H.; Campbell, K. M.; Stubbs, J. E.; Suvorova, E.; Lezama-Pacheco, J. S.; Alessi, D.; Stylo, M.; Handley, K. M.; Bernier-Latmani, R.; Cerrato, J.; Davis, J. A.; Fox, P. M.; Giammar, D.; Long, P. E.

    2011-12-01

    The chemical and physical forms of U(IV) in reduced sediments, as well as the biogeochemical processes by which they form and transform, profoundly influence the stability of reduced U(IV) species and the behavior of uranium in biostimulated aquifers. Obtaining such information in field sediments is important because biogeochemical field conditions and their time dependence are difficult to replicate in the laboratory. The majority of contaminated aquifers in which bioremediation is of potential interest, including the Old Rifle, CO IFRC site, exhibit relatively low uranium sediment concentrations, i.e., < 10 ppm, presenting a formidable challenge to the use of spectroscopy and microscopy techniques that typically require 10-fold or higher uranium loadings. We have developed an in-situ column technique to study U(IV) species and evolving microbial communities in the Old Rifle aquifer and to correlate them with changes in trace and major ion groundwater composition during biostimulation treatments. Sediments were examined using x-ray and electron microscopy, x-ray absorption spectroscopy (XAS), and chemical extractions. XAS analysis showed that U(IV) occurred predominantly or exclusively as monomeric U(IV) complexes coordinated to oxo (or similar N/C) neighbors, and is associated with biomass or Fe sulfides. Even in the latter case, U(IV) was not coordinated directly to S neighbors. Sediment-hosted monomeric U(IV) complexes were found to partially transform into uraninite in the aquifer over a subsequent 12 month period. This work establishes the importance of monomeric U(IV) complexes in subsurface sediments at the Old Rifle site and provides a conceptual framework in which previously observed U(IV) reduction products can be related. These experiments also establish that U(IV) species are dynamic in aquifers and can undergo non-oxidative transformation reactions. These new results have important implications for uranium reactive transport models, long

  20. SWECS tower dynamics analysis methods and results

    NASA Technical Reports Server (NTRS)

    Wright, A. D.; Sexton, J. H.; Butterfield, C. P.; Thresher, R. M.

    1981-01-01

    Several different tower dynamics analysis methods and computer codes were used to determine the natural frequencies and mode shapes of both guyed and freestanding wind turbine towers. These analysis methods are described and the results for two types of towers, a guyed tower and a freestanding tower, are shown. The advantages and disadvantages in the use of and the accuracy of each method are also described.

  1. Final Report Computational Analysis of Dynamical Systems

    SciTech Connect

    Guckenheimer, John

    2012-05-08

    This is the final report for DOE Grant DE-FG02-93ER25164, initiated in 1993. This grant supported research of John Guckenheimer on computational analysis of dynamical systems. During that period, seventeen individuals received PhD degrees under the supervision of Guckenheimer and over fifty publications related to the grant were produced. This document contains copies of these publications.

  2. Speciation Mapping of Environmental Samples Using XANES Imaging

    EPA Science Inventory

    Fast X-ray detectors with large solid angles and high dynamic ranges open the door to XANES imaging, in which millions of spectra are collected to image the speciation of metals at micrometre resolution, over areas up to several square centimetres. This paper explores how such mu...

  3. Metacommunity speciation models and their implications for diversification theory.

    PubMed

    Hubert, Nicolas; Calcagno, Vincent; Etienne, Rampal S; Mouquet, Nicolas

    2015-08-01

    The emergence of new frameworks combining evolutionary and ecological dynamics in communities opens new perspectives on the study of speciation. By acknowledging the relative contribution of local and regional dynamics in shaping the complexity of ecological communities, metacommunity theory sheds a new light on the mechanisms underlying the emergence of species. Three integrative frameworks have been proposed, involving neutral dynamics, niche theory, and life history trade-offs respectively. Here, we review these frameworks of metacommunity theory to emphasise that: (1) studies on speciation and community ecology have converged towards similar general principles by acknowledging the central role of dispersal in metacommunities dynamics, (2) considering the conditions of emergence and maintenance of new species in communities has given rise to new models of speciation embedded in the metacommunity theory, (3) studies of diversification have shifted from relating phylogenetic patterns to landscapes spatial and ecological characteristics towards integrative approaches that explicitly consider speciation in a mechanistic ecological framework. We highlight several challenges, in particular the need for a better integration of the eco-evolutionary consequences of dispersal and the need to increase our understanding on the relative rates of evolutionary and ecological changes in communities.

  4. Speciation Mapping of Environmental Samples Using XANES Imaging

    EPA Science Inventory

    Fast X-ray detectors with large solid angles and high dynamic ranges open the door to XANES imaging, in which millions of spectra are collected to image the speciation of metals at micrometre resolution, over areas up to several square centimetres. This paper explores how such mu...

  5. Double-sided Microfluidic Device for Speciation Analysis of Iron in Water Samples: Towards Greener Analytical Chemistry.

    PubMed

    Youngvises, Napaporn; Thanurak, Porapichcha; Chaida, Thanatcha; Jukmunee, Jaroon; Alsuhaimi, Awadh

    2015-01-01

    Microfluidics minimize the amounts of reagents and generate less waste. While microdevices are commonly single-sided, producing a substrate with microchannels on multiple surfaces would increase their usefulness. Herein, a polymethymethacrylate substrate incorporating microchannel structures on two sides was sandwiched between two polydimethylsiloxane sheets to create a multi-analysis device, which was used for the spectrophotometric analysis of the ferrous ion (Fe(2+)) and the ferric ion (Fe(3+)), by utilizing colorimetric detection. To monitor the signals from both channel networks, dual optical sensors were integrated into the system. The linear ranges for Fe(2+) and Fe(3+) analyses were 0.1 - 20 mg L(-1) (R(2) = 0.9988) and 1.0 - 40 mg L(-1) (R(2) = 0.9974), respectively. The detection limits for Fe(2+) and Fe(3+) were 0.1 and 0.5 mg L(-1), respectively. The percent recoveries of Fe(2+) and Fe(3+) were 93.5 - 104.3 with an RSD < 8%. The microdevice demonstrated capabilities for simultaneous analysis, low waste generation (7.2 mL h(-1)), and high sample throughput (180 h(-1)), making it ideal for greener analytical chemistry applications.

  6. CORRELATING METAL SPECIATION IN SOILS

    EPA Science Inventory

    Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

  7. CORRELATING METAL SPECIATION IN SOILS

    EPA Science Inventory

    Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

  8. Sympatric speciation: compliance with phenotype diversification from a single genotype.

    PubMed Central

    Kaneko, K; Yomo, T

    2000-01-01

    A novel mechanism for sympatric speciation that takes into account complex bioprocesses within each individual organism is proposed. According to dynamical systems theory, organisms with identical genotypes can possess differentiated physiological states and may coexist 'symbiotically' through appropriate mutual interaction. With mutations, the phenotypically differentiated organisms gradually come to possess distinct genotypes while maintaining their symbiotic relationship. This symbiotic speciation is robust against sexual recombination, because offspring of mixed parentage with intermediate genotypes are less fit than their parents. This leads to sterility of the hybrid. Accordingly, a basis for mating preference also arises. PMID:11133025

  9. Speciation of vanadium in soil.

    PubMed

    Połedniok, Justyna; Buhl, Franciszek

    2003-01-02

    A method for speciation of vanadium in soil is presented in this work. The sequential extraction analysis procedure of Tessier et al. for heavy metals was used for the vanadium separation. The method consists of sequential leaching of the soil samples to separate five fractions of metals: (1) exchangeable, (2) bound to carbonates, (3) bound to Fe-Mn oxides, (4) bound to organic matter and (5) residual. The leaching solutions of Tessier were used for the vanadium extraction, only for the residual fraction the HClO(4) was replaced with H(2)SO(4). The optimum conditions for leaching of vanadium from soil (weight of sample, concentration and volume of extractants, time of extraction) were chosen for each fraction. A sensitive, spectrophotometric method based on the ternary complex V(IV) with Chrome Azurol S and benzyldodecyldimethylammonium bromide (epsilon=7.1x10(4) l mol(-1) cm(-1)) was applied for the vanadium determination after separation of V(V) by solvent extraction using mesityl oxide and reduction of V(V) using ascorbic acid. This method was applied for vanadium speciation in soil from two different regions of Poland: Upper Silesia (industrial region) and Podlasie (agricultural region). The content of vanadium in the fractions of Upper Silesia soil was respectively (in 10(-3)%): I, 3.39; III, 4.53; IV, 10.70; V, 8.70 and it was the highest in the organic fraction, indicating input by anthropogenic activities. The content of vanadium in Podlasie soil was clearly lower and it was (in 10(-3)%): I, 2.07; III, 0.92; IV, 0.69; V, 1.23. The concentration of vanadium in fraction 2 of both soils was less than detection limit of applied method. The total content of vanadium in the five soil fractions was in good correlation with the total content of this element in both soils found after HF-H(2)SO(4) digestion. Analysis using the ICP-AES method gave comparable results.

  10. Nonlinear dynamics and quantitative EEG analysis.

    PubMed

    Jansen, B H

    1996-01-01

    Quantitative, computerized electroencephalogram (EEG) analysis appears to be based on a phenomenological approach to EEG interpretation, and is primarily rooted in linear systems theory. A fundamentally different approach to computerized EEG analysis, however, is making its way into the laboratories. The basic idea, inspired by recent advances in the area of nonlinear dynamics and chaos theory, is to view an EEG as the output of a deterministic system of relatively simple complexity, but containing nonlinearities. This suggests that studying the geometrical dynamics of EEGs, and the development of neurophysiologically realistic models of EEG generation may produce more successful automated EEG analysis techniques than the classical, stochastic methods. A review of the fundamentals of chaos theory is provided. Evidence supporting the nonlinear dynamics paradigm to EEG interpretation is presented, and the kind of new information that can be extracted from the EEG is discussed. A case is made that a nonlinear dynamic systems viewpoint to EEG generation will profoundly affect the way EEG interpretation is currently done.

  11. Dynamical analysis of generalized Galileon cosmology

    SciTech Connect

    Leon, Genly; Saridakis, Emmanuel N. E-mail: Emmanuel_Saridakis@baylor.edu

    2013-03-01

    We perform a detailed dynamical analysis of generalized Galileon cosmology, incorporating also the requirements of ghost and instabilities absence. We find that there are not any new stable late-time solutions apart from those of standard quintessence. Furthermore, depending on the model parameters the Galileons may survive at late times or they may completely disappear by the dynamics, however the corresponding observables are always independent of the Galileon terms, determined only by the usual action terms. Thus, although the Galileons can play an important role at inflationary or at recent times, in the future, when the universe will asymptotically reach its stable state, they will not have any effect on its evolution.

  12. Flight Dynamics Analysis Branch 2005 Technical Highlights

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This report summarizes the major activities and accomplishments carried out by the Flight Dynamics Analysis Branch (FDAB), Code 595, in support of flight projects and technology development initiatives in Fiscal Year (FY) 2005. The report is intended to serve as a summary of the type of support carried out by the FDAB, as well as a concise reference of key accomplishments and mission experience derived from the various mission support roles. The primary focus of the FDAB is to provide expertise in the disciplines of flight dynamics including spacecraft navigation (autonomous and ground based); spacecraft trajectory design and maneuver planning; attitude analysis; attitude determination and sensor calibration; and attitude control subsystem (ACS) analysis and design. The FDAB currently provides support for missions and technology development projects involving NASA, other government agencies, academia, and private industry.

  13. Nanometer-sized alumina packed microcolumn solid-phase extraction combined with field-amplified sample stacking-capillary electrophoresis for the speciation analysis of inorganic selenium in environmental water samples.

    PubMed

    Duan, Jiankuan; Hu, Bin; He, Man

    2012-10-01

    In this paper, a new method of nanometer-sized alumina packed microcolumn SPE combined with field-amplified sample stacking (FASS)-CE-UV detection was developed for the speciation analysis of inorganic selenium in environmental water samples. Self-synthesized nanometer-sized alumina was packed in a microcolumn as the SPE adsorbent to retain Se(IV) and Se(VI) simultaneously at pH 6 and the retained inorganic selenium was eluted by concentrated ammonia. The eluent was used for FASS-CE-UV analysis after NH₃ evaporation. The factors affecting the preconcentration of both Se(IV) and Se(VI) by SPE and FASS were studied and the optimal CE separation conditions for Se(IV) and Se(VI) were obtained. Under the optimal conditions, the LODs of 57 ng L⁻¹ (Se(IV)) and 71 ng L⁻¹ (Se(VI)) were obtained, respectively. The developed method was validated by the analysis of a certified reference material of GBW(E)080395 environmental water and the determined value was in a good agreement with the certified value. It was also successfully applied to the speciation analysis of inorganic selenium in environmental water samples, including Yangtze River water, spring water, and tap water. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Speciation analysis of lead in marine animals by using capillary electrophoresis couple online with inductively coupled plasma mass spectrometry.

    PubMed

    Chen, Yiquan; Huang, Limei; Wu, Weihua; Ruan, Yajuan; Wu, Zujian; Xue, Zhimin; Fu, FengFu

    2014-05-01

    We herein reported a environment-friendly microwave-assisted extraction used to extract trace lead compounds from marine animals and a ultrasensitive method for the analysis of Pb²⁺, trimethyl lead chloride (TML) and triethyl lead chloride (TEL) by using CE-ICP-MS. The extraction method is simple and has a high extracting efficiency. It can be used to completely extract both inorganic lead and organolead in marine animal samples without altering its species. The analytical method has a detection limit as low as 0.012-0.084 ng Pb/mL for Pb²⁺, TML, and TEL, and can be used to determine ultratrace Pb²⁺, TML, and TEL in marine animals directly without any preconcentration. With the help of above methods, we have successfully determined Pb²⁺, TML, and TEL in clam and oyster tissue within 20 min with a RSD (n = 6) < 5% and a recovery of 91-104%. Our results showed that Pb²⁺ was the main species of lead in clam and oyster, and organolead (TML) was only found in oyster. The proposed method provides a realistic approach for the accurate evaluation of lead pollution in seafood.

  15. Cluster analysis of word frequency dynamics

    NASA Astrophysics Data System (ADS)

    Maslennikova, Yu S.; Bochkarev, V. V.; Belashova, I. A.

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations.

  16. Zeolite Beta Formation from Clear Sols: Silicate Speciation, Particle Formation and Crystallization Monitored by Complementary Analysis Methods.

    PubMed

    Castro, Maria; Haouas, Mohamed; Lim, Ivy; Bongard, Hans J; Schüth, Ferdi; Taulelle, Francis; Karlsson, Gunnel; Alfredsson, Viveka; Breyneart, Eric; Kirschhock, Christine E A; Schmidt, Wolfgang

    2016-10-17

    The formation of silicate nanoaggregates (NAs) at the very early stages of precursor sols and zeolite beta crystallization from silicate nanoparticles (NPs) are investigated in detail using a combination of different analysis methods, including liquid-state (29) Si, (27) Al, (14) N, and (1) H NMR spectroscopy, mass spectrometry (MS), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and transmission electron microscopy at cryogenic temperatures (cryo-TEM). Prior to hydrothermal treatment, silicate NAs are observed if the Si/OH ratio in the reaction mixture is greater than 1. Condensation of oligomers within the NAs then generates NPs. Aluminum doped into the synthesis mixtures is located exclusively in the NPs, and is found exclusively in a state that is fourfold connected to silicate, favoring their condensation and aggregation. These results are in agreement with general trends observed for other systems. Silicate NAs are essential intermediates for zeolite formation and are generated by the aggregation of hydrated oligomers, aluminate, and templating cations. Subsequent further intra-nanoaggregate silicate condensation results in the formation of NPs. (1) H and (14) N liquid NMR as well as diffusion ordered spectroscopy (DOSY) experiments provide evidence for weakly restricted rotational and translational mobility of the organic template within NAs as a consequence of specific silicate-template interactions. NAs thus appear as key species in clear sols, and their presence in the precursor sol favors silicate condensation and further crystallization, promoted either by increasing the Si/OH ratio or by heating. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Sexual conflict and speciation.

    PubMed Central

    Parker, G A; Partridge, L

    1998-01-01

    We review the significance of two forms of sexual conflict (different evolutionary interests of the two sexes) for genetic differentiation of populations and the evolution of reproductive isolation. Conflicting selection on the alleles at a single locus can occur in males and females if the sexes have different optima for a trait, and there are pleiotropic genetic correlations between the sexes for it. There will then be selection for sex limitation and hence sexual dimorphism. This sex limitation could break down in hybrids and reduce their fitness. Pleiotropic genetic correlations between the sexes could also affect the likelihood of mating in interpopulation encounters. Conflict can also occur between (sex-limited) loci that determine behaviour in males and those that determine behaviour in females. Reproductive isolation may occur by rapid coevolution of male trait and female mating preference. This would tend to generate assortative mating on secondary contact, hence promoting speciation. Sexual conflict resulting from sensory exploitation, polyspermy and the cost of mating could result in high levels of interpopulation mating. If females evolve resistance to make pre- and postmating manipulation, males from one population could be more successful with females from the other, because females would have evolved resistance to their own (but not to the allopatric) males. Between-locus sexual conflict could also occur as a result of conflict between males and females of different populations over the production of unfit hybrids. We develop models which show that females are in general selected to resist such matings and males to persist, and this could have a bearing on both the initial level of interpopulation matings and the likelihood that reinforcement will occur. In effect, selection on males usually acts to promote gene flow and to restrict premating isolation, whereas selection on females usually acts in the reverse direction. We review theoretical models

  18. Precise Analysis of Polymer Rotational Dynamics

    PubMed Central

    Kim, Jun Mo; Baig, Chunggi

    2016-01-01

    Through the analysis of individual chain dynamics alongside the corresponding molecular structures under shear via nonequilibrium molecular dynamics simulations of C178H358 linear and short-chain branched polyethylene melts under shear flow, we observed that the conventional method based on the chain end-to-end vector (and/or the gyration tensor of chain) is susceptible to quantitatively inaccurate measurements and often misleading information in describing the rotational dynamics of polymers. Identifying the flaw as attributed to strong irregular Brownian fluctuations inherent to the chain ends associated with their large free volume and strong molecular collisions, we propose a simple, robust way based on the chain center-to-center vector connecting the two centers of mass of the bisected chain, which is shown to adequately describe polymer rotational dynamics without such shortcomings. We present further consideration that the proposed method can be useful in accurately measuring the overall chain structure and dynamics of polymeric materials with various molecular architectures, including branched and ring polymers. PMID:26743689

  19. The effect of phytostabilization on Zn speciation in a dredged contaminated sediment using scanning electron microscopy, X-ray fluorescence, EXAFS spectroscopy, and principal components analysis

    NASA Astrophysics Data System (ADS)

    Panfili, Frédéric; Manceau, Alain; Sarret, Géraldine; Spadini, Lorenzo; Kirpichtchikova, Tatiana; Bert, Valérie; Laboudigue, Agnès; Marcus, Matthew A.; Ahamdach, Noureddine; Libert, Marie-Françoise

    2005-05-01

    The maintenance of waterways generates large amounts of dredged sediments, which are deposited on adjacent land surfaces. These sediments are often rich in metal contaminants and present a risk to the local environment. Understanding how the metals are immobilized at the molecular level is critical for formulating effective metal containment strategies such as phytoremediation. In the present work, the mineralogical transformations of Zn-containing phases induced by two graminaceous plants (A grostis tenuis and Festuca rubra) in a contaminated sediment ([Zn] = 4700 mg kg -1, [P 2O 5] = 7000 mg kg -1, pH = 7.8), untreated or amended with hydroxylapatite (AP) or Thomas basic slag (TS), were investigated after two yr of pot experiment by scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS), synchrotron-based X-ray microfluorescence (μ-SXRF), and powder and laterally resolved extended X-ray absorption fine structure (μ-EXAFS) spectroscopy. The number and nature of Zn species were evaluated by principal component (PCA) and least-squares fitting (LSF) analysis of the entire set of μ-EXAFS spectra, which included up to 32 individual spectra from regions of interest varying in chemical composition. Seven Zn species were identified at the micrometer scale: sphalerite, gahnite, franklinite, Zn-containing ferrihydrite and phosphate, (Zn-Al)-hydrotalcite, and Zn-substituted kerolite-like trioctahedral phyllosilicate. Bulk fractions of each species were quantified by LSF of the powder EXAFS spectra to linear combinations of the identified Zn species spectra. In the untreated and unvegetated sediment, Zn was distributed as ˜50% (mole ratio of total Zn) sphalerite, ˜40% Zn-ferrihydrite, and ˜10 to 20% (Zn-Al)-hydrotalcite plus Zn-phyllosilicate. In unvegetated but amended sediments (AP and TS), ZnS and Zn-ferrihydrite each decreased by 10 to 20% and were replaced by Zn-phosphate (˜30˜40%). In the presence of plants, ZnS was almost completely

  20. Phylogeographic analysis of a temperate-deciduous forest restricted plant (Bupleurum longiradiatum Turcz.) reveals two refuge areas in China with subsequent refugial isolation promoting speciation.

    PubMed

    Zhao, Cai; Wang, Chang-Bao; Ma, Xiang-Guang; Liang, Qian-Long; He, Xing-Jin

    2013-09-01

    . Additionally, geological conditions that restricted gene flow might also be responsible for the observed high genetic and geographic differentiation. A nested clade analysis (NCA) revealed that allopatric fragmentation was a major factor responsible for the phylogeographic pattern observed, and also supported a role for historical vicariance factors. Our results therefore support the inference that Quaternary refugial isolation promoted allopatric speciation of temperate plants in East Asia. This may help to explain the existence of high diversity and endemism of plant species in East Asia.

  1. Arabidopsis hybrid speciation processes

    PubMed Central

    Schmickl, Roswitha; Koch, Marcus A.

    2011-01-01

    The genus Arabidopsis provides a unique opportunity to study fundamental biological questions in plant sciences using the diploid model species Arabidopsis thaliana and Arabidopsis lyrata. However, only a few studies have focused on introgression and hybrid speciation in Arabidopsis, although polyploidy is a common phenomenon within this genus. More recently, there is growing evidence of significant gene flow between the various Arabidopsis species. So far, we know Arabidopsis suecica and Arabidopsis kamchatica as fully stabilized allopolyploid species. Both species evolved during Pleistocene glaciation and deglaciation cycles in Fennoscandinavia and the amphi-Beringian region, respectively. These hybrid studies were conducted either on a phylogeographic scale or reconstructed experimentally in the laboratory. In our study we focus at a regional and population level. Our research area is located in the foothills of the eastern Austrian Alps, where two Arabidopsis species, Arabidopsis arenosa and A. lyrata ssp. petraea, are sympatrically distributed. Our hypothesis of genetic introgression, migration, and adaptation to the changing environment during the Pleistocene has been confirmed: We observed significant, mainly unidirectional gene flow between the two species, which has given rise to the tetraploid A. lyrata. This cytotype was able to escape from the narrow ecological niche occupied by diploid A. lyrata ssp. petraea on limestone outcrops by migrating northward into siliceous areas, leaving behind a trail of genetic differentiation. PMID:21825128

  2. Epock: rapid analysis of protein pocket dynamics.

    PubMed

    Laurent, Benoist; Chavent, Matthieu; Cragnolini, Tristan; Dahl, Anna Caroline E; Pasquali, Samuela; Derreumaux, Philippe; Sansom, Mark S P; Baaden, Marc

    2015-05-01

    The volume of an internal protein pocket is fundamental to ligand accessibility. Few programs that compute such volumes manage dynamic data from molecular dynamics (MD) simulations. Limited performance often prohibits analysis of large datasets. We present Epock, an efficient command-line tool that calculates pocket volumes from MD trajectories. A plugin for the VMD program provides a graphical user interface to facilitate input creation, run Epock and analyse the results. Epock C++ source code, Python analysis scripts, VMD Tcl plugin, documentation and installation instructions are freely available at http://epock.bitbucket.org. benoist.laurent@gmail.com or baaden@smplinux.de Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press.

  3. Complementary arsenic speciation methods: A review

    NASA Astrophysics Data System (ADS)

    Nearing, Michelle M.; Koch, Iris; Reimer, Kenneth J.

    2014-09-01

    The toxicity of arsenic greatly depends on its chemical form and oxidation state (speciation) and therefore accurate determination of arsenic speciation is a crucial step in understanding its chemistry and potential risk. High performance liquid chromatography with inductively coupled mass spectrometry (HPLC-ICP-MS) is the most common analysis used for arsenic speciation but it has two major limitations: it relies on an extraction step (usually from a solid sample) that can be incomplete or alter the arsenic compounds; and it provides no structural information, relying on matching sample peaks to standard peaks. The use of additional analytical methods in a complementary manner introduces the ability to address these disadvantages. The use of X-ray absorption spectroscopy (XAS) with HPLC-ICP-MS can be used to identify compounds not extracted for HPLC-ICP-MS and provide minimal processing steps for solid state analysis that may help preserve labile compounds such as those containing arsenicsbnd sulfur bonds, which can degrade under chromatographic conditions. On the other hand, HPLC-ICP-MS is essential in confirming organoarsenic compounds with similar white line energies seen by using XAS, and identifying trace arsenic compounds that are too low to be detected by XAS. The complementary use of electrospray mass spectrometry (ESI-MS) with HPLC-ICP-MS provides confirmation of arsenic compounds identified during the HPLC-ICP-MS analysis, identification of unknown compounds observed during the HPLC-ICP-MS analysis and further resolves HPLC-ICP-MS by identifying co-eluting compounds. In the complementary use of HPLC-ICP-MS and ESI-MS, HPLC-ICP-MS helps to focus the ESI-MS selection of ions. Numerous studies have shown that the information obtained from HPLC-ICP-MS analysis can be greatly enhanced by complementary approaches.

  4. Dynamic analysis of dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Xu, Bai-Xiang; Mueller, Ralf; Theis, Anika; Klassen, Markus; Gross, Dietmar

    2012-03-01

    An analytical model is proposed for the dynamic analysis of a homogeneously deformed dielectric elastomer actuator (DEA) with a standard sandwich structure. The equation of motion for the DEA is obtained by the Euler-Lagrange equation. Numerical results of the model are presented to show the vibration and oscillation behaviour of the system. Resonance phenomenon and damping effects are investigated. Results are discussed in comparison with those of the related topics in the literature.

  5. Simplified Dynamic Analysis of Grinders Spindle Node

    NASA Astrophysics Data System (ADS)

    Demec, Peter

    2014-12-01

    The contribution deals with the simplified dynamic analysis of surface grinding machine spindle node. Dynamic analysis is based on the use of the transfer matrix method, which is essentially a matrix form of method of initial parameters. The advantage of the described method, despite the seemingly complex mathematical apparatus, is primarily, that it does not require for solve the problem of costly commercial software using finite element method. All calculations can be made for example in MS Excel, which is advantageous especially in the initial stages of constructing of spindle node for the rapid assessment of the suitability its design. After detailing the entire structure of spindle node is then also necessary to perform the refined dynamic analysis in the environment of FEM, which it requires the necessary skills and experience and it is therefore economically difficult. This work was developed within grant project KEGA No. 023TUKE-4/2012 Creation of a comprehensive educational - teaching material for the article Production technique using a combination of traditional and modern information technology and e-learning.

  6. Sexual selection drives speciation in an Amazonian frog

    USGS Publications Warehouse

    Boul, K.E.; Funk, W.C.; Darst, C.R.; Cannatella, D.C.; Ryan, M.J.

    2007-01-01

    One proposed mechanism of speciation is divergent sexual selection, whereby divergence in female preferences and male signals results in behavioural isolation. Despite the appeal of this hypothesis, evidence for it remains inconclusive. Here, we present several lines of evidence that sexual selection is driving behavioural isolation and speciation among populations of an Amazonian frog (Physalaemus petersi). First, sexual selection has promoted divergence in male mating calls and female preferences for calls between neighbouring populations, resulting in strong behavioural isolation. Second, phylogenetic analysis indicates that populations have become fixed for alternative call types several times throughout the species' range, and coalescent analysis rejects genetic drift as a cause for this pattern, suggesting that this divergence is due to selection. Finally, gene flow estimated with microsatellite loci is an average of 30 times lower between populations with different call types than between populations separated by a similar geographical distance with the same call type, demonstrating genetic divergence and incipient speciation. Taken together, these data provide strong evidence that sexual selection is driving behavioural isolation and speciation, supporting sexual selection as a cause for speciation in the wild. ?? 2006 The Royal Society.

  7. Vehicle dynamic analysis using neuronal network algorithms

    NASA Astrophysics Data System (ADS)

    Oloeriu, Florin; Mocian, Oana

    2014-06-01

    Theoretical developments of certain engineering areas, the emergence of new investigation tools, which are better and more precise and their implementation on-board the everyday vehicles, all these represent main influence factors that impact the theoretical and experimental study of vehicle's dynamic behavior. Once the implementation of these new technologies onto the vehicle's construction had been achieved, it had led to more and more complex systems. Some of the most important, such as the electronic control of engine, transmission, suspension, steering, braking and traction had a positive impact onto the vehicle's dynamic behavior. The existence of CPU on-board vehicles allows data acquisition and storage and it leads to a more accurate and better experimental and theoretical study of vehicle dynamics. It uses the information offered directly by the already on-board built-in elements of electronic control systems. The technical literature that studies vehicle dynamics is entirely focused onto parametric analysis. This kind of approach adopts two simplifying assumptions. Functional parameters obey certain distribution laws, which are known in classical statistics theory. The second assumption states that the mathematical models are previously known and have coefficients that are not time-dependent. Both the mentioned assumptions are not confirmed in real situations: the functional parameters do not follow any known statistical repartition laws and the mathematical laws aren't previously known and contain families of parameters and are mostly time-dependent. The purpose of the paper is to present a more accurate analysis methodology that can be applied when studying vehicle's dynamic behavior. A method that provides the setting of non-parametrical mathematical models for vehicle's dynamic behavior is relying on neuronal networks. This method contains coefficients that are time-dependent. Neuronal networks are mostly used in various types' system controls, thus

  8. Oxidation State Specific Generation of Arsines from Methylated Arsenicals Based on L- Cysteine Treatment in Buffered Media for Speciation Analysis by Hydride Generation - Automated Cryotrapping - Gas Chromatography-Atomic Absorption Spectrometry with the Multiatomizer

    PubMed Central

    Matoušek, Tomáš; Hernández-Zavala, Araceli; Svoboda, Milan; Langrová, Lenka; Adair, Blakely M.; Drobná, Zuzana; Thomas, David J.; Stýblo, Miroslav; Dědina, Jiří

    2008-01-01

    An automated system for hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer is described. Arsines are preconcentrated and separated in a Chromosorb filled U-tube. An automated cryotrapping unit, employing nitrogen gas formed upon heating in the detection phase for the displacement of the cooling liquid nitrogen, has been developed. The conditions for separation of arsines in a Chromosorb filled U-tube have been optimized. A complete separation of signals from arsine, methylarsine, dimethylarsine, and trimethylarsine has been achieved within a 60 s reading window. The limits of detection for methylated arsenicals tested were 4 ng l−1. Selective hydride generation is applied for the oxidation state specific speciation analysis of inorganic and methylated arsenicals. The arsines are generated either exclusively from trivalent or from both tri- and pentavalent inorganic and methylated arsenicals depending on the presence of L-cysteine as a prereductant and/or reaction modifier. A TRIS buffer reaction medium is proposed to overcome narrow optimum concentration range observed for the L-cysteine modified reaction in HCl medium. The system provides uniform peak area sensitivity for all As species. Consequently, the calibration with a single form of As is possible. This method permits a high-throughput speciation analysis of metabolites of inorganic arsenic in relatively complex biological matrices such as cell culture systems without sample pretreatment, thus preserving the distribution of tri- and pentavalent species. PMID:18521190

  9. Dynamic feature analysis in bidirectional pedestrian flows

    NASA Astrophysics Data System (ADS)

    Xiao-Xia, Yang; Winnie, Daamen; Serge, Paul Hoogendoorn; Hai-Rong, Dong; Xiu-Ming, Yao

    2016-02-01

    Analysis of dynamic features of pedestrian flows is one of the most exciting topics in pedestrian dynamics. This paper focuses on the effect of homogeneity and heterogeneity in three parameters of the social force model, namely desired velocity, reaction time, and body size, on the moving dynamics of bidirectional pedestrian flows in the corridors. The speed and its deviation in free flows are investigated. Simulation results show that the homogeneous higher desired speed which is less than a critical threshold, shorter reaction time or smaller body size results in higher speed of flows. The free dynamics is more sensitive to the heterogeneity in desired speed than that in reaction time or in body size. In particular, an inner lane formation is observed in normal lanes. Furthermore, the breakdown probability and the start time of breakdown are focused on. This study reveals that the sizes of homogeneous desired speed, reaction time or body size play more important roles in affecting the breakdown than the heterogeneities in these three parameters do. Project supported jointly by the National Natural Science Foundation of China (Grant No. 61233001) and the Fundamental Research Funds for Central Universities of China (Grant No. 2013JBZ007).

  10. Expansion of epicyclic gear dynamic analysis program

    NASA Technical Reports Server (NTRS)

    Boyd, Linda Smith; Pike, James A.

    1987-01-01

    The multiple mesh/single stage dynamics program is a gear tooth analysis program which determines detailed geometry, dynamic loads, stresses, and surface damage factors. The program can analyze a variety of both epicyclic and single mesh systems with spur or helical gear teeth including internal, external, and buttress tooth forms. The modifications refine the options for the flexible carrier and flexible ring gear rim and adds three options: a floating Sun gear option; a natural frequency option; and a finite element compliance formulation for helical gear teeth. The option for a floating Sun incorporates two additional degrees of freedom at the Sun center. The natural frequency option evaluates the frequencies of planetary, star, or differential systems as well as the effect of additional springs at the Sun center and those due to a flexible carrier and/or ring gear rim. The helical tooth pair finite element calculated compliance is obtained from an automated element breakup of the helical teeth and then is used with the basic gear dynamic solution and stress postprocessing routines. The flexible carrier or ring gear rim option for planetary and star spur gear systems allows the output torque per carrier and ring gear rim segment to vary based on the dynamic response of the entire system, while the total output torque remains constant.

  11. Speciation of Energy Critical Elements in Marine Ferromanganese Crusts and Nodules by Principal Component Analysis and Least-squares fits to XAFS Spectra

    NASA Astrophysics Data System (ADS)

    Foster, A. L.; Klofas, J. M.; Hein, J. R.; Koschinsky, A.; Bargar, J.; Dunham, R. E.; Conrad, T. A.

    2011-12-01

    Marine ferromanganese crusts and nodules ("Fe-Mn crusts") are considered a potential mineral resource due to their accumulation of several economically-important elements at concentrations above mean crustal abundances. They are typically composed of intergrown Fe oxyhydroxide and Mn oxide; thicker (older) crusts can also contain carbonate fluorapatite. We used X-ray absorption fine-structure (XAFS) spectroscopy, a molecular-scale structure probe, to determine the speciation of several elements (Te, Bi, Mo, Zr, Pt) in Fe-Mn crusts. As a first step in analysis of this dataset, we have conducted principal component analysis (PCA) of Te K-edge and Mo K-edge, k3-weighted XAFS spectra. The sample set consisted of 12 homogenized, ground Fe-Mn crust samples from 8 locations in the global ocean. One sample was subjected to a chemical leach to selectively remove Mn oxides and the elements associated with it. The samples in the study set contain 50-205 mg/kg Te (average = 88) and 97-802 mg/kg Mo (average = 567). PCAs of background-subtracted, normalized Te K-edge and Mo K-edge XAFS spectra were performed on a data matrix of 12 rows x 122 columns (rows = samples; columns = Te or Mo fluorescence value at each energy step) and results were visualized without rotation. The number of significant components was assessed by the Malinowski indicator function and ability of the components to reconstruct the features (minus noise) of all sample spectra. Two components were significant by these criteria for both Te and Mo PCAs and described a total of 74 and 75% of the total variance, respectively. Reconstruction of potential model compounds by the principal components derived from PCAs on the sample set ("target transformation") provides a means of ranking models in terms of their utility for subsequent linear-combination, least-squares (LCLS) fits (the next step of data analysis). Synthetic end-member models of Te4+, Te6+, and Mo adsorbed to Fe(III) oxyhydroxide and Mn oxide were

  12. Structural dynamic analysis of composite beams

    NASA Astrophysics Data System (ADS)

    Suresh, J. K.; Venkatesan, C.; Ramamurti, V.

    1990-12-01

    In the treatment of the structural dynamic problem of composite materials, two alternate types of formulations, based on the elastic modulus and compliance quantities, exist in the literature. The definitions of the various rigidities are observed to differ in these two approaches. Following these two types of formulation, the structural dynamic characteristics of a composite beam are analyzed. The results of the analysis are compared with those available in the literature. Based on the comparison, the influence of the warping function in defining the coupling terms in the modulus approach and also on the natural frequencies of the beam has been identified. It is found from the analysis that, in certain cases, the difference between the results of the two approaches is appreciable. These differences may be attributed to the constraints imposed on the deformation and flexibility of the beam by the choice of the description of the warping behaviour. Finally, the influence of material properties on the structural dynamic characteristics of the beam is studied for different composites for various angles of orthotropy.

  13. Microscale characterization of sulfur speciation in lake sediments.

    PubMed

    Zeng, Teng; Arnold, William A; Toner, Brandy M

    2013-02-05

    Prairie pothole lakes (PPLs) are naturally sulfur-enriched wetlands in the glaciated prairie region of North America. High sulfate levels and dynamic hydrogeochemistry in combination render PPLs a unique environment to explore the speciation of sedimentary sulfur (S). The goals of this research were to define and quantify the solid-phase S pools in PPL sediments and track seasonal dynamics of S speciation. A quantitative X-ray microprobe method was developed based on S 1s X-ray absorption near-edge structure (XANES) spectroscopy and multienergy X-ray fluorescence mapping. Three S pools-pyritic S, reduced organic S (organic mono- and disulfide), and oxidized S (inorganic sulfate, ester sulfate, and sulfonate)-were identified in PPL sediments. No significant seasonal variation was evident for total S, but S speciation showed a seasonal response. During the spring-summer transition, the reduced organic S decreased from 55 to 15 mol %, with a concomitant rise in the oxidized S. During the summer-fall transition, the trend reversed and the reduced organic S grew to 75 mol % at the expense of the oxidized S. The pyritic S, on the other hand, remained relatively constant (∼22 mol %) over time. The seasonal changes in S speciation have strong potential to force the cycling of elements such as mercury in prairie wetlands.

  14. Ecology, sexual selection and speciation.

    PubMed

    Maan, Martine E; Seehausen, Ole

    2011-06-01

    The spectacular diversity in sexually selected traits among animal taxa has inspired the hypothesis that divergent sexual selection can drive speciation. Unfortunately, speciation biologists often consider sexual selection in isolation from natural selection, even though sexually selected traits evolve in an ecological context: both preferences and traits are often subject to natural selection. Conversely, while behavioural ecologists may address ecological effects on sexual communication, they rarely measure the consequences for population divergence. Herein, we review the empirical literature addressing the mechanisms by which natural selection and sexual selection can interact during speciation. We find that convincing evidence for any of these scenarios is thin. However, the available data strongly support various diversifying effects that emerge from interactions between sexual selection and environmental heterogeneity. We suggest that evaluating the evolutionary consequences of these effects requires a better integration of behavioural, ecological and evolutionary research. © 2011 Blackwell Publishing Ltd/CNRS.

  15. Velocity fluctuation analysis via dynamic programming

    SciTech Connect

    Schlossberg, D. J.; Gupta, D. K.; Fonck, R. J.; McKee, G. R.; Shafer, M. W.

    2006-10-15

    A new method of calculating one-dimensional velocity fluctuations from spatially resolved density fluctuation measurements is presented. The algorithm uses vector-matching methods of dynamic programming that match structures, such as turbulent fluctuations, in two data sets. The associated time delay between data sets is estimated by determining an optimal path to transform one vector to another. This time-delay-estimation (TDE) method establishes a new benchmark for velocity analysis by achieving higher sensitivity and frequency response than previously developed methods, such as time-resolved cross correlations and wavelets. TDE has been successfully applied to beam emission spectroscopy measurements of density fluctuations to obtain poloidal flow fluctuations associated with such phenomena as the geodesic acoustic mode. The dynamic programming algorithm should allow extension to high frequency velocity fluctuations associated with underlying electrostatic potential and resulting ExB fluctuations.

  16. Sexual selection and speciation in mammals, butterflies and spiders.

    PubMed Central

    Gage, Matthew J G; Parker, Geoffrey A; Nylin, Soren; Wiklund, Christer

    2002-01-01

    Recently refined evolutionary theories propose that sexual selection and reproductive conflict could be drivers of speciation. Male and female reproductive optima invariably differ because the potential reproductive rate of males almost always exceeds that of females: females are selected to maximize mate 'quality', while males can increase fitness through mate 'quantity'. A dynamic, sexually selected conflict therefore exists in which 'competitive' males are selected to override the preference tactics evolved by 'choosy' females. The wide variation across taxa in mating systems therefore generates variance in the outcome of intrasexual conflict and the strength of sexual selection: monandry constrains reproductive heterozygosity and allows female choice to select and maintain particular (preferred) genes; polyandry promotes reproductive heterozygosity and will more likely override female choice. Two different theories predict how sexual selection might influence speciation. Traditional ideas indicate that increased sexual selection (and hence conflict) generates a greater diversity of male reproductive strategies to be counteracted by female mate preferences, thus providing elevated potentials for speciation as more evolutionary avenues of male-female interaction are created. A less intuitively obvious theory proposes that increased sexual selection and conflict constrains speciation by reducing the opportunities for female mate choice under polyandry. We use a comparative approach to test these theories by investigating whether two general measures of sexual selection and the potential for sexual conflict have influenced speciation. Sexual size dimorphism (across 480 mammalian genera, 105 butterfly genera and 148 spider genera) and degree of polyandry (measured as relative testes size in mammals (72 genera) and mating frequency in female butterflies (54 genera)) showed no associations with the variance in speciosity. Our results therefore show that speciation

  17. Sexual selection and speciation in mammals, butterflies and spiders.

    PubMed

    Gage, Matthew J G; Parker, Geoffrey A; Nylin, Soren; Wiklund, Christer

    2002-11-22

    Recently refined evolutionary theories propose that sexual selection and reproductive conflict could be drivers of speciation. Male and female reproductive optima invariably differ because the potential reproductive rate of males almost always exceeds that of females: females are selected to maximize mate 'quality', while males can increase fitness through mate 'quantity'. A dynamic, sexually selected conflict therefore exists in which 'competitive' males are selected to override the preference tactics evolved by 'choosy' females. The wide variation across taxa in mating systems therefore generates variance in the outcome of intrasexual conflict and the strength of sexual selection: monandry constrains reproductive heterozygosity and allows female choice to select and maintain particular (preferred) genes; polyandry promotes reproductive heterozygosity and will more likely override female choice. Two different theories predict how sexual selection might influence speciation. Traditional ideas indicate that increased sexual selection (and hence conflict) generates a greater diversity of male reproductive strategies to be counteracted by female mate preferences, thus providing elevated potentials for speciation as more evolutionary avenues of male-female interaction are created. A less intuitively obvious theory proposes that increased sexual selection and conflict constrains speciation by reducing the opportunities for female mate choice under polyandry. We use a comparative approach to test these theories by investigating whether two general measures of sexual selection and the potential for sexual conflict have influenced speciation. Sexual size dimorphism (across 480 mammalian genera, 105 butterfly genera and 148 spider genera) and degree of polyandry (measured as relative testes size in mammals (72 genera) and mating frequency in female butterflies (54 genera)) showed no associations with the variance in speciosity. Our results therefore show that speciation

  18. Are we analyzing speciation without prejudice?

    PubMed

    Johannesson, Kerstin

    2010-09-01

    Physical isolation has long been the null hypothesis of speciation, with exceptional evidence required to suggest speciation with gene flow. Following recent persuasive theoretical support and strong empirical examples of nonallopatric speciation, one might expect a changed view. However, a review of 73 recent empirical studies shows that when allopatric speciation is suggested, a nonallopatric alternative is rarely considered, whereas the opposite is true in studies suggesting sympatric speciation, indicating a biased treatment of different speciation models. Although increasing support for ecological speciation suggests natural selection as the most critical component of speciation, gene flow remains an issue. Methods for unbiased hypothesis testing are available, and the genetic and phylogeographic data required for appropriate tests can be generated. Focus on phylogenies and functions of individual genes have revealed strong idiosyncratic elements of speciation, such as single genes with possible allopatric origin that make significant contributions during nonallopatric phases of speciation. Hence a more complex picture of speciation is now emerging that will benefit from unbiased evaluation of both allopatric and sympatric mechanisms of speciation.

  19. Extreme changes to gene expression associated with homoploid hybrid speciation.

    PubMed

    Hegarty, Matthew J; Barker, Gary L; Brennan, Adrian C; Edwards, Keith J; Abbott, Richard J; Hiscock, Simon J

    2009-03-01

    Hybridization is an important cause of abrupt speciation. Hybrid speciation without a change in ploidy (homoploid hybrid speciation) is well-established in plants but has also been reported in animals and fungi. A notable example of recent homoploid hybrid speciation is Senecio squalidus (Oxford ragwort), which originated in the UK in the 18th Century following introduction of hybrid material from a hybrid zone between S. chrysanthemifolius and S. aethnensis on Mount Etna, Sicily. To investigate genetic divergence between these taxa, we used complementary DNA microarrays to compare patterns of floral gene expression. These analyses revealed major differences in gene expression between the parent species and wild and resynthesized S. squalidus. Comparisons of gene expression between S. aethnensis, S. chrysanthemifolius and natural S. squalidus identified genes potentially involved in local environmental adaptation. The analysis also revealed non-additive patterns of gene expression in the hybrid relative to its progenitors. These expression changes were more dramatic and widespread in resynthesized hybrids than in natural S. squalidus, suggesting that a unique expression pattern may have been fixed during the allopatric divergence of British S. squalidus. We speculate that hybridization-induced gene-expression change may provide an immediate source of novel phenotypic variation upon which selection can act to facilitate homoploid hybrid speciation in plants.

  20. Computational stability analysis of dynamical systems

    NASA Astrophysics Data System (ADS)

    Nikishkov, Yuri Gennadievich

    2000-10-01

    Due to increased available computer power, the analysis of nonlinear flexible multi-body systems, fixed-wing aircraft and rotary-wing vehicles is relying on increasingly complex, large scale models. An important aspect of the dynamic response of flexible multi-body systems is the potential presence of instabilities. Stability analysis is typically performed on simplified models with the smallest number of degrees of freedom required to capture the physical phenomena that cause the instability. The system stability boundaries are then evaluated using the characteristic exponent method or Floquet theory for systems with constant or periodic coefficients, respectively. As the number of degrees of freedom used to represent the system increases, these methods become increasingly cumbersome, and quickly unmanageable. In this work, a novel approach is proposed, the Implicit Floquet Analysis, which evaluates the largest eigenvalues of the transition matrix using the Arnoldi algorithm, without the explicit computation of this matrix. This method is far more computationally efficient than the classical approach and is ideally suited for systems involving a large number of degrees of freedom. The proposed approach is conveniently implemented as a postprocessing step to any existing simulation tool. The application of the method to a geometrically nonlinear multi-body dynamics code is presented. This work also focuses on the implementation of trimming algorithms and the development of tools for the graphical representation of numerical simulations and stability information for multi-body systems.

  1. A genomic perspective on hybridization and speciation

    PubMed Central

    Payseur, Bret A.; Rieseberg, Loren H.

    2016-01-01

    Hybridization among diverging lineages is common in nature. Genomic data provide a special opportunity to characterize the history of hybridization and the genetic basis of speciation. We review existing methods and empirical studies to identify recent advances in the genomics of hybridization, as well as issues that need to be addressed. Notable progress has been made in the development of methods for detecting hybridization and inferring individual ancestries. However, few approaches reconstruct the magnitude and timing of gene flow, estimate the fitness of hybrids or incorporate knowledge of recombination rate. Empirical studies indicate that the genomic consequences of hybridization are complex, including a highly heterogeneous landscape of differentiation. Inferred characteristics of hybridization differ substantially among species groups. Loci showing unusual patterns – which may contribute to reproductive barriers – are usually scattered throughout the genome, with potential enrichment in sex chromosomes and regions of reduced recombination. We caution against the growing trend of interpreting genomic variation in summary statistics across genomes as evidence of differential gene flow. We argue that converting genomic patterns into useful inferences about hybridization will ultimately require models and methods that directly incorporate key ingredients of speciation, including the dynamic nature of gene flow, selection acting in hybrid populations and recombination rate variation. PMID:26836441

  2. Architectural Analysis of Dynamically Reconfigurable Systems

    NASA Technical Reports Server (NTRS)

    Lindvall, Mikael; Godfrey, Sally; Ackermann, Chris; Ray, Arnab; Yonkwa, Lyly

    2010-01-01

    oTpics include: the problem (increased flexibility of architectural styles decrease analyzability, behavior emerges and varies depending on the configuration, does the resulting system run according to the intended design, and architectural decisions can impede or facilitate testing); top down approach to architecture analysis, detection of defects and deviations, and architecture and its testability; currently targeted projects GMSEC and CFS; analyzing software architectures; analyzing runtime events; actual architecture recognition; GMPUB in Dynamic SAVE; sample output from new approach; taking message timing delays into account; CFS examples of architecture and testability; some recommendations for improved testablity; and CFS examples of abstract interfaces and testability; CFS example of opening some internal details.

  3. Stock index dynamics worldwide: a comparative analysis

    NASA Astrophysics Data System (ADS)

    Cortines, A. A. G.; Anteneodo, C.; Riera, R.

    2008-09-01

    We perform a comparative analysis of twenty-four daily stock indices across the world, encompassing developed and emerging markets. We compute, directly from the return empirical time series, the Kramers-Moyal (KM) expansion coefficients that govern the evolution of the probability density function of returns throughout timelags. Our study discloses universal patterns of the KM coefficients, which can be described in terms of a few microscopic parameters. These parameters allow to quantify features such as deviations from Gaussianity or from efficiency, providing a tool to discriminate market dynamics.

  4. HL-20 computational fluid dynamics analysis

    NASA Astrophysics Data System (ADS)

    Weilmuenster, K. James; Greene, Francis A.

    1993-09-01

    The essential elements of a computational fluid dynamics analysis of the HL-20/personnel launch system aerothermal environment at hypersonic speeds including surface definition, grid generation, solution techniques, and visual representation of results are presented. Examples of solution technique validation through comparison with data from ground-based facilities are presented, along with results from computations at flight conditions. Computations at flight points indicate that real-gas effects have little or no effect on vehicle aerodynamics and, at these conditions, results from approximate techniques for determining surface heating are comparable with those obtained from Navier-Stokes solutions.

  5. HL-20 computational fluid dynamics analysis

    NASA Technical Reports Server (NTRS)

    Weilmuenster, K. J.; Greene, Francis A.

    1993-01-01

    The essential elements of a computational fluid dynamics analysis of the HL-20/personnel launch system aerothermal environment at hypersonic speeds including surface definition, grid generation, solution techniques, and visual representation of results are presented. Examples of solution technique validation through comparison with data from ground-based facilities are presented, along with results from computations at flight conditions. Computations at flight points indicate that real-gas effects have little or no effect on vehicle aerodynamics and, at these conditions, results from approximate techniques for determining surface heating are comparable with those obtained from Navier-Stokes solutions.

  6. Perturbation analysis for patch occupancy dynamics

    USGS Publications Warehouse

    Martin, Julien; Nichols, James D.; McIntyre, Carol L.; Ferraz, Goncalo; Hines, James E.

    2009-01-01

    Perturbation analysis is a powerful tool to study population and community dynamics. This article describes expressions for sensitivity metrics reflecting changes in equilibrium occupancy resulting from small changes in the vital rates of patch occupancy dynamics (i.e., probabilities of local patch colonization and extinction). We illustrate our approach with a case study of occupancy dynamics of Golden Eagle (Aquila chrysaetos) nesting territories. Examination of the hypothesis of system equilibrium suggests that the system satisfies equilibrium conditions. Estimates of vital rates obtained using patch occupancy models are used to estimate equilibrium patch occupancy of eagles. We then compute estimates of sensitivity metrics and discuss their implications for eagle population ecology and management. Finally, we discuss the intuition underlying our sensitivity metrics and then provide examples of ecological questions that can be addressed using perturbation analyses. For instance, the sensitivity metrics lead to predictions about the relative importance of local colonization and local extinction probabilities in influencing equilibrium occupancy for rare and common species.

  7. Hybrid speciation in birds: allopatry more important than ecology?

    PubMed

    Brelsford, Alan

    2011-09-01

    Hybrid speciation was once thought to be rare in animals, but over the past decade, improved molecular analysis techniques and increased research attention have allowed scientists to uncover many examples. In this issue, two papers (Elgvin et al. 2011; Hermansen et al. 2011) present compelling evidence for the hybrid origin of the Italian sparrow based on nuclear and mitochondrial DNA sequences, microsatellites, and plumage coloration. These studies point to an important role for geographic isolation in the process of hybrid speciation, and provide a starting point for closer examination of the genetic and behavioural mechanisms involved. © 2011 Blackwell Publishing Ltd.

  8. XANES Identification of Plutonium Speciation in RFETS Samples

    SciTech Connect

    LoPresti, V.; Conradson, S.D.; Clark, D.L.

    2009-06-03

    Using primarily X-ray absorption near edge spectroscopy (XANES) with standards run in tandem with samples, probable plutonium speciation was determined for 13 samples from contaminated soil, acid-splash or fire-deposition building interior surfaces, or asphalt pads from the Rocky Flats Environmental Technology Site (RFETS). Save for extreme oxidizing situations, all other samples were found to be of Pu(IV) speciation, supporting the supposition that such contamination is less likely to show mobility off site. EXAFS analysis conducted on two of the 13 samples supported the validity of the XANES features employed as determinants of the plutonium valence.

  9. Dynamic Factor Analysis Models with Time-Varying Parameters

    ERIC Educational Resources Information Center

    Chow, Sy-Miin; Zu, Jiyun; Shifren, Kim; Zhang, Guangjian

    2011-01-01

    Dynamic factor analysis models with time-varying parameters offer a valuable tool for evaluating multivariate time series data with time-varying dynamics and/or measurement properties. We use the Dynamic Model of Activation proposed by Zautra and colleagues (Zautra, Potter, & Reich, 1997) as a motivating example to construct a dynamic factor…

  10. Dynamic Factor Analysis Models with Time-Varying Parameters

    ERIC Educational Resources Information Center

    Chow, Sy-Miin; Zu, Jiyun; Shifren, Kim; Zhang, Guangjian

    2011-01-01

    Dynamic factor analysis models with time-varying parameters offer a valuable tool for evaluating multivariate time series data with time-varying dynamics and/or measurement properties. We use the Dynamic Model of Activation proposed by Zautra and colleagues (Zautra, Potter, & Reich, 1997) as a motivating example to construct a dynamic factor…

  11. How common is homoploid hybrid speciation?

    PubMed

    Schumer, Molly; Rosenthal, Gil G; Andolfatto, Peter

    2014-06-01

    Hybridization has long been considered a process that prevents divergence between species. In contrast to this historical view, an increasing number of empirical studies claim to show evidence for hybrid speciation without a ploidy change. However, the importance of hybridization as a route to speciation is poorly understood, and many claims have been made with insufficient evidence that hybridization played a role in the speciation process. We propose criteria to determine the strength of evidence for homoploid hybrid speciation. Based on an evaluation of the literature using this framework, we conclude that although hybridization appears to be common, evidence for an important role of hybridization in homoploid speciation is more circumscribed.

  12. Heavy metal pollution in vegetables grown in the vicinity of a multi-metal mining area in Gejiu, China: total concentrations, speciation analysis, and health risk.

    PubMed

    Li, Yanyan; Wang, Hongbin; Wang, Haijuan; Yin, Fei; Yang, Xiaoyan; Hu, Yongjun

    2014-11-01

    A field survey was conducted to investigate the present situation and health risk of arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in soils and vegetables in a multi-metal mining area, Gejiu, China. Furthermore, three vegetables (water spinach, potato, and summer squash) containing high metal concentrations were selected to further analyze metal speciation. The results showed that the average concentrations of five metals in soil exceeded the limiting values, and their bioavailable concentrations were significantly positively correlated to the total ones. Heavy metals in the edible parts of vegetables also exceeded the corresponding standards. The leaves of pakchoi, peppermint, and coriander had a strong metal-accumulative ability and they were not suitable for planting. Except the residue forms, the main forms of metals in the edible parts of three selected vegetables were ethanol-, NaCl-, and HAc-extractable fractions for As, Pb, and Cd, respectively; however, Cu was mainly presented as NaCl-extractable and Zn as HAc-extractable fractions. A high proportion of ethanol-extractable As showed that As bioactivity and toxic effects were the highest. Although the total and bioavailable Cd were high in soil, its speciation in vegetables was mainly presented as HAc-extractable fraction, which has a relatively low bioactivity. Lead and arsenic were imposing a serious threat on the local residents via vegetable consumption.

  13. Dynamic analysis of the Milad Tower

    NASA Astrophysics Data System (ADS)

    Wilhelm, Edwin; Ford, Mitchell; Coelho, Darren; Lawler, Lachlan; Ansourian, Peter; Alonso-Marroquin, Fernando; Tahmasebinia, Faham

    2016-08-01

    This report involves the modelling of the Milad Tower using the finite element analysis program Strand7. A dynamic analysis was performed on the structure in order to understand the deflections and stresses as a result of earthquake and wind loading. In particular, Linear Static as well as Natural Frequency and Spectral Response solvers were used to determine the behaviour of the structure under loading. The findings of the report highlight that the structure was modelled accurately with the outputs representing realistic values. The report suggests that the design of the beams, columns, slabs and all structural members was sufficient enough to support the tower during maximum loading cases. The governing load case was earthquake loading.

  14. Mytoe: automatic analysis of mitochondrial dynamics.

    PubMed

    Lihavainen, Eero; Mäkelä, Jarno; Spelbrink, Johannes N; Ribeiro, Andre S

    2012-04-01

    We present Mytoe, a tool for analyzing mitochondrial morphology and dynamics from fluorescence microscope images. The tool provides automated quantitative analysis of mitochondrial motion by optical flow estimation and of morphology by segmentation of individual branches of the network-like structure of the organelles. Mytoe quantifies several features of individual branches, such as length, tortuosity and speed, and of the macroscopic structure, such as mitochondrial area and degree of clustering. We validate the methods and apply them to the analysis of sequences of images of U2OS human cells with fluorescently labeled mitochondria. Source code, Windows software and Manual available at http://www.cs.tut.fi/%7Esanchesr/mito Supplementary data are available at Bioinformatics online. eero.lihavainen@tut.fi; andre.ribeiro@tut.fi.

  15. Dynamic Numerical Analysis of Steel Footbridge

    NASA Astrophysics Data System (ADS)

    Major, Maciej; Minda, Izabela; Major, Izabela

    2017-06-01

    The study presents a numerical analysis of the arched footbridge designed in two variants, made of steel and aluminium. The first part presents the criteria for evaluation of the comfort of using the footbridges. The study examined the footbridge with arched design with span in the axis of 24 m and width of 1.4 m. Arch geometry was made as a part of the circle with radius of r = 20 m cut off with a chord with length equal to the calculation length of the girders. The model of the analysed footbridge was subjected to the dynamic effect of wind and the pedestrian traffic with variable flexibility. The analyses used Robot Structural Analysis software.

  16. A statistical model for bacterial speciation triggered by lateral gene transfer

    NASA Astrophysics Data System (ADS)

    Sidhu, Sunjeet; Peng, Wequin

    2006-03-01

    The process of bacterial speciation has been a major unresolved issue in the study of bacterial evolution. It has been proposed that lateral gene transfer and homologous recombination play critical and complementary roles in speciation. We introduce a statistical model, of a population, for the evolution under lateral gene transfer and local homologous recombination. We examine the evolutionary dynamics and its dependence on various evolutionary operators. J. G. Lawrence, Theor. Popul. Biol. 61, 449(2002).

  17. Comparative Sensitivity Analysis of Muscle Activation Dynamics

    PubMed Central

    Rockenfeller, Robert; Günther, Michael; Schmitt, Syn; Götz, Thomas

    2015-01-01

    We mathematically compared two models of mammalian striated muscle activation dynamics proposed by Hatze and Zajac. Both models are representative for a broad variety of biomechanical models formulated as ordinary differential equations (ODEs). These models incorporate parameters that directly represent known physiological properties. Other parameters have been introduced to reproduce empirical observations. We used sensitivity analysis to investigate the influence of model parameters on the ODE solutions. In addition, we expanded an existing approach to treating initial conditions as parameters and to calculating second-order sensitivities. Furthermore, we used a global sensitivity analysis approach to include finite ranges of parameter values. Hence, a theoretician striving for model reduction could use the method for identifying particularly low sensitivities to detect superfluous parameters. An experimenter could use it for identifying particularly high sensitivities to improve parameter estimation. Hatze's nonlinear model incorporates some parameters to which activation dynamics is clearly more sensitive than to any parameter in Zajac's linear model. Other than Zajac's model, Hatze's model can, however, reproduce measured shifts in optimal muscle length with varied muscle activity. Accordingly we extracted a specific parameter set for Hatze's model that combines best with a particular muscle force-length relation. PMID:26417379

  18. PM 2.5 ORGANIC SPECIATION INTERCOMPARISON RESULTS

    EPA Science Inventory

    This abstract describes a poster on results to a laboratory intercomparison of organic aerosol speciation analysis to be presented at the 2006 International Aerosol Conference sponsored by the American Association for Aerosol Research in St. Paul, Minnesota on September 10-15. T...

  19. Dynamic characterization and analysis of space shuttle SRM solid propellant

    NASA Technical Reports Server (NTRS)

    Hufferd, W. L.

    1979-01-01

    The dynamic response properties of the space shuttle solid rocket moter (TP-H1148) propellant were characterized and the expected limits of propellant variability were established. Dynamic shear modulus tests conducted on six production batches of TP-H1148 at various static and dynamic strain levels over the temperature range from 40 F to 90 F. A heat conduction analysis and dynamic response analysis of the space shuttle solid rocket motor (SRM) were also conducted. The dynamic test results show significant dependence on static and dynamic strain levels and considerable batch-to-batch and within-batch variability. However, the results of the SRM dynamic response analyses clearly demonstrate that the stiffness of the propellant has no consequential on the overall SRM dynamic response. Only the mass of the propellant needs to be considered in the dynamic analysis of the space shuttle SRM.

  20. SPECIATED VOC EMISSIONS FROM MODERN GDI LIGHT ...

    EPA Pesticide Factsheets

    Chassis dynamometer emissions testing was conducted to characterize speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs) and ozone precursors, in exhaust emissions from three modern gasoline direct injection (GDI) light-duty vehicles. Each GDI vehicle tested in this study utilized slightly different fuel injection technology: Vehicle 1 used a 2.4 liter, naturally aspirated, wall-guided GDI; Vehicle 2 used a 1.8 liter, turbocharged GDI engine; Vehicle 3 used a 1.5 liter, turbocharged, spray-guided GDI engine. Vehicle testing was conducted in a temperature controlled chassis dynamometer test cell at 22 °C over the EPA Federal Test Procedure (FTP) and a portion of the Supplemental FTP (SFTP). The FTP was conducted as a three phase cycle with a cold start, hot transient, and warm start phase (also known as the FTP-75 driving cycle). The SFTP consisted of the US06 driving cycle (conducted without the vehicle’s air conditioning on), which provides a more aggressive driving pattern than the FTP. The vehicles operated on 10 percent ethanol blended gasoline (E10). VOC emissions from diluted vehicle exhaust were sampled over each FTP phase and over the Supplemental FTP with SUMMA canisters for EPA Method TO-15 analysis and with DNPH cartridges for carbonyl analysis by EPA Method TO-11A. This presentation will report the impact of driving cycle and GDI technology on speciated MSAT emissions. MSAT emission rates will be compared

  1. Air toxics speciation of landfill gas

    SciTech Connect

    Potas, T.A.

    1998-12-31

    USEPA`s AP-42, emission factor reference manual lists 27 hazardous air pollutants that have been determined to be present in gas generated at landfills. Different AP-42 values are given for some air toxic compounds generated from municipal solid waste, industrial waste, and hazardous waste. This paper compares data compiled from five landfill gas sampling projects in parts per million with the AP-42 data. The sampling took place at landfills containing municipal solid waste and non-hazardous industrial waste. Sampling was performed according to the Tier 2 testing procedures for total non-methane organic compound concentrations described in the New Source Performance Standards Subpart WWW for Municipal Solid Waste Landfills. The speciation analysis was conducted by EPA Method TO-14. The list of TO-14 compounds for the speciation analysis was extended to include, at a minimum, all 27 AP-42 listed hazardous air pollutant compounds. The landfills included sites from across the country. The paper describes data quality and the effect of landfill age on some individual air toxic concentrations. The author also comments on the agreement between the total non-methane organic compound concentration and the total molecular weight equivalent concentration of the individual compound concentrations. In general, the concentration values were similar for the AP-42 compounds, although several AP-42 compounds were not detected.

  2. Aero-Thermo-Dynamic Mass Analysis

    PubMed Central

    Shiba, Kota; Yoshikawa, Genki

    2016-01-01

    Each gas molecule has its own molecular weight, while such a microscopic characteristic is generally inaccessible, and thus, it is measured indirectly through e.g. ionization in conventional mass analysis. Here, we present a novel approach to the direct measurement of molecular weight through a nanoarchitectonic combination of aerodynamics, thermodynamics, and mechanics, transducing microscopic events into macroscopic phenomena. It is confirmed that this approach can provide molecular weight of virtually any gas or vaporizable liquid sample in real-time without ionization. Demonstrations through analytical calculations, numerical simulations, and experiments verify the validity and versatility of the novel mass analysis realized by a simple setup with a flexible object (e.g. with a bare cantilever and even with a business card) placed in a laminar jet. Owing to its unique and simple working principle, this aero-thermo-dynamic mass analysis (AMA) can be integrated into various analytical devices, production lines, and consumer mobile platforms, opening new chapters in aerodynamics, thermodynamics, mechanics, and mass analysis. PMID:27412335

  3. Aero-Thermo-Dynamic Mass Analysis.

    PubMed

    Shiba, Kota; Yoshikawa, Genki

    2016-07-14

    Each gas molecule has its own molecular weight, while such a microscopic characteristic is generally inaccessible, and thus, it is measured indirectly through e.g. ionization in conventional mass analysis. Here, we present a novel approach to the direct measurement of molecular weight through a nanoarchitectonic combination of aerodynamics, thermodynamics, and mechanics, transducing microscopic events into macroscopic phenomena. It is confirmed that this approach can provide molecular weight of virtually any gas or vaporizable liquid sample in real-time without ionization. Demonstrations through analytical calculations, numerical simulations, and experiments verify the validity and versatility of the novel mass analysis realized by a simple setup with a flexible object (e.g. with a bare cantilever and even with a business card) placed in a laminar jet. Owing to its unique and simple working principle, this aero-thermo-dynamic mass analysis (AMA) can be integrated into various analytical devices, production lines, and consumer mobile platforms, opening new chapters in aerodynamics, thermodynamics, mechanics, and mass analysis.

  4. Aero-Thermo-Dynamic Mass Analysis

    NASA Astrophysics Data System (ADS)

    Shiba, Kota; Yoshikawa, Genki

    2016-07-01

    Each gas molecule has its own molecular weight, while such a microscopic characteristic is generally inaccessible, and thus, it is measured indirectly through e.g. ionization in conventional mass analysis. Here, we present a novel approach to the direct measurement of molecular weight through a nanoarchitectonic combination of aerodynamics, thermodynamics, and mechanics, transducing microscopic events into macroscopic phenomena. It is confirmed that this approach can provide molecular weight of virtually any gas or vaporizable liquid sample in real-time without ionization. Demonstrations through analytical calculations, numerical simulations, and experiments verify the validity and versatility of the novel mass analysis realized by a simple setup with a flexible object (e.g. with a bare cantilever and even with a business card) placed in a laminar jet. Owing to its unique and simple working principle, this aero-thermo-dynamic mass analysis (AMA) can be integrated into various analytical devices, production lines, and consumer mobile platforms, opening new chapters in aerodynamics, thermodynamics, mechanics, and mass analysis.

  5. Pushing back the frontiers of mercury speciation using a combination of biomolecular and isotopic signatures: challenge and perspectives.

    PubMed

    Pedrero, Zoyne; Donard, Olivier F X; Amouroux, David

    2016-04-01

    Mercury (Hg) pollution is considered a major environmental problem due to the extreme toxicity of Hg. However, Hg metabolic pathways in biota remain elusive. An understanding of these pathways is crucial to elucidating the (eco)toxic effects of Hg and its biogeochemical cycle. The development of a new analytical methodology based on both speciation and natural isotopic fractionation represents a promising approach for metabolic studies of Hg and other metal(loid)s. Speciation provides valuable information about the reactivity and potential toxicity of metabolites, while the use of natural isotopic signature analysis adds a complementary dynamic dimension that allows the life history of the target element to be probed, the source of the target element (i.e., the source of pollution) to be identified, and reactions to be tracked. The resulting combined (bio)molecular and isotopic signature affords precious insight into the behavior of Hg in biota and Hg detoxification mechanisms. In the long term, this highly innovative methodology could be used in life and environmental science studies of metal(loid)s to push back the frontiers of our knowledge in this field. This paper summarizes the current status of the application of Hg speciation and the isotopic signature of Hg at the biomolecular level in living organisms, and discusses potential future uses of this combination of techniques.

  6. Questions concerning environmental mobility of arsenic: needs for a chemical data base and means for speciation of trace organoarsenicals.

    PubMed Central

    Brinckman, F E; Parris, G E; Blair, W R; Jewett, K L; Iverson, W P; Bellama, J M

    1977-01-01

    Biomethylation of metals, including arsenic, apparently occurs as a global process. Health control strategies therefore depend on accurate analysis of arsenic's environmental mobility. Determining to what extent biotransformations occur and how resultant organometal(loids) are sequestered in food chains requires sophistication beyond present-day total element determinations. Rather, active molecular forms of arsenic must be speciated for each environmental compartment, and it is necessary to quantify the dynamics of arsenic's mobility. Thus, new chemical facts are needed yielding rates of methylation or demethylation of arsenic; partition coefficients of organoarsenicals between air, water, and organic phases; and arsenic redox chemistry in polar media. NBS research in this context is reviewed with examples of recent results emphasizing speciation methodology. Topic areas discussed are: the nature of aquated methylarsenic species (NMR and laser-Raman spectroscopy); transport of methylarsenicals from aqueous media (gas chromatography-graphic furnace AA detection applied to metabolic Me3As formation); and speciation of involatile organoarsenicals in aqueous media (demonstration of HPLC utilizing element-specific AA detection and appraisal of electrochemical detectors). PMID:908286

  7. Patterns of plant speciation in the Cape floristic region.

    PubMed

    van der Niet, Timotheüs; Johnson, Steven D

    2009-04-01

    Plant species have accumulated in the Cape region of southern Africa to a much greater degree than in areas of equivalent size in the rest of the subcontinent. Although this could be a consequence simply of lower extinction rates in the Cape, most researchers have invoked high rates of ecological speciation, driven by unique aspects of the Cape environment, as the primary explanation for this richness. To assess these ideas, we analyzed the frequencies of ecological shifts among 188 sister species pairs obtained from molecular phylogenies of eight Cape clades. Ecological shifts were evident in 80% of sister species pairs, with general habitat, pollinator, and fire-survival strategy shifts being especially frequent. Contrary to an established idea that shifts in soil type are frequently associated with speciation of Cape taxa, these shifts were relatively rare, occurring in just 17% of species pairs. More cases of sister species divergence are accompanied solely by floral than by vegetative diversification, suggesting an important role for pollinator-driven speciation. In an analysis of two large orchid genera that have radiated in both the Cape and the rest of southern Africa, the frequency of ecological shifts (general habitat, soil type, altitude and flowering time), did not differ between sister species pairs in the Cape region and those outside it. Despite suggestions that Cape plants tend to have small range sizes and show fine-scale patterns of speciation, range size did not differ significantly between species in the Cape and those outside it. We conclude that ecological speciation is likely to have been important for radiation of the Cape flora, but there is no evidence as yet for special "Cape" patterns of ecological speciation.

  8. Sequential photocatalyst-assisted digestion and vapor generation device coupled with anion exchange chromatography and inductively coupled plasma mass spectrometry for speciation analysis of selenium species in biological samples.

    PubMed

    Tsai, Yun-ni; Lin, Cheng-hsing; Hsu, I-hsiang; Sun, Yuh-chang

    2014-01-02

    We have developed an on-line sequential photocatalyst-assisted digestion and vaporization device (SPADVD), which operates through the nano-TiO2-catalyzed photo-oxidation and reduction of selenium (Se) species, for coupling between anion exchange chromatography (LC) and inductively coupled plasma mass spectrometry (ICP-MS) systems to provide a simple and sensitive hyphenated method for the speciation analysis of Se species without the need for conventional chemical digestion and vaporization techniques. Because our proposed on-line SPADVD allows both organic and inorganic Se species in the column effluent to be converted on-line into volatile Se products, which are then measured directly through ICP-MS, the complexity of the procedure and the probability of contamination arising from the use of additional chemicals are both low. Under the optimized conditions for SPADVD - using 1g of nano-TiO2 per liter, at pH 3, and illuminating for 80 s - we found that Se(IV), Se(VI), and selenomethionine (SeMet) were all converted quantitatively into volatile Se products. In addition, because the digestion and vaporization efficiencies of all the tested selenicals were improved when using our proposed on-line LC/SPADVD/ICP-MS system, the detection limits for Se(IV), Se(VI), and SeMet were all in the nanogram-per-liter range (based on 3σ). A series of validation experiments - analysis of neat and spiked extracted samples - indicated that our proposed methods could be applied satisfactorily to the speciation analysis of organic and inorganic Se species in the extracts of Se-enriched supplements.

  9. Continuous diesel emissions speciation with a transportable MBMS system

    SciTech Connect

    Ratcliff, M.A.; Gratson, D.A.; Milne, T.A.

    1995-03-01

    A unique transportable molecular beam mass spectrometer (TMBMS) has been developed at the National Renewable Energy Laboratory (NREL) to extend the virtues of MBMS analysis to new applications beyond the traditional laboratory scope and scale. The TMBMS is based on a three stage vacuum system; the transport capability dictated the minimization of size. weight and required utilities. The instrument has demonstrated a dynamic range of at least 10{sup 6} and a limit of detection of 0.5 ppmv, depending on the species and system being investigated. The instrument has been successfully used as a continuous emissions monitor and a chemical process monitor. Continuous, near real-time speciation of diesel exhaust demonstrated the potential of MBMS analysis in the field of emissions monitoring. Controlled steady state and transient tests were conducted with conventional diesel and soybean derived methyl-ester biodiesel fuels. The emissions differences between the two fuels were readily apparent, with the diesel fuel producing higher concentrations of hydrocarbon species. It was statistically demonstrated that many unburned diesel fuel hydrocarbons can be reproducibly detected and followed under a variety of steady state conditions. Carbon dioxide, water, nitric oxide and sulfur dioxide were monitored simultaneously with the unburned hydrocarbons. The transient testing demonstrated the instruments ability to follow changes, on the seconds time scale, of multiple combustion products as a function of engine speed, load and throttle position.

  10. Summary of EOS flight dynamics analysis

    NASA Technical Reports Server (NTRS)

    Newman, Lauri Kraft; Folta, David C.

    1995-01-01

    From a flight dynamics perspective, the Earth Observing System (EOS) spacecraft present a number of challenges to mission designers. The Flight Dynamics Support Branch of NASA GSFC has examined a number of these challenges, including managing the EOS constellation, disposing of the spacecraft at the end-of-life (EOL), and achieving the appropriate mission orbit given launch vehicle and ascent propulsion constraints. The EOS program consists of a number of spacecraft including EOS-AM, an ascending node spacecraft, EOS-PM, a descending node spacecraft, the EOS Chemistry mission (EOS-CHEM), the EOS Altimetry Laser (EOS-LALT), and the EOS-Altimetry Radar (EOS-RALT). The orbit characteristics of these missions are presented. In order to assure that downlinking data from each spacecraft will be possible without interference between any two spacecraft, a careful examination of the relationships between spacecraft and how to maintain the spacecraft in a configuration which would minimize these communications problems must be made. The FDSB has performed various analyses to determine whether the spacecraft will be in a position to interfere with each other, how the orbit dynamics will change the relative positioning of the spacecraft over their lifetimes, and how maintenance maneuvers could be performed, if needed, to minimize communications problems. Prompted by an activity at NASA HQ to set guidelines for spacecraft regarding their end-of-life dispositions, much analysis has also been performed to determine the spacecraft lifetime of EOS-AM1 under various conditions, and to make suggestions regarding the spacecraft disposal. In performing this analysis, some general trends have been observed in lifetime calculations. The paper will present the EOS-AM1 lifetime results, comment on general reentry conclusions, and discuss how these analyses reflect on the HQ NMI. Placing the EOS spacecraft into their respective mission orbits involves some intricate maneuver planning to

  11. Dynamic smile analysis: changes with age.

    PubMed

    Desai, Shyam; Upadhyay, Madhur; Nanda, Ravindra

    2009-09-01

    The objective of this study was to define age-related changes in the smile. The areas of interest were upper lip length at smile and repose, upper lip thickness at smile and repose, maxillary incisal display at smile, interlabial gap height at smile, smile index, percentage of buccal corridors, intercommissural width at rest, smile height, and smile arc. A secondary objective was to study the perioral changes from rest to smile and compare them on the basis of age. Video equipment was used to capture images of 261 subjects, who were divided into 5 groups by age. Two frames for each subject were selected, 1 frame representing the lips at rest and the other representing the widest smile. After 40 subjects were excluded, the data for the remaining 221 were analyzed by using 1-way analysis of variance (ANOVA) with the Fisher LSD post-hoc test. There was a decrease of 1.5 to 2 mm in maxillary incisor display during smile with increasing age, but the smile index showed a significant increase. In accordance with some other studies, most subjects (78%) had average smile height. No subject in the 50 and over age group had a high smile, and no subject in the 15-to-19 year group had a low smile. All dynamic measurements indicated a pattern of decreasing change from rest to smile, especially evident after ages 30 to 39 years. This study helps to establish age-related dynamic norms. As a person ages, the smile gets narrower vertically and wider transversely. The dynamic measures indicate that the muscles' ability to create a smile decreases with increasing age.

  12. Dynamic Analysis of Mobile Device Applications

    SciTech Connect

    Corey Thuen

    2013-01-01

    The On-Device Dynamic Analysis of Mobile Applications (ODAMA) project was started in an effort to protect mobile devices used in Industrial Control Systems (ICS) from cyber attack. Because mobile devices hide as much of the “computer” as possible, the user’s ability to assess the software running on their system is limited. The research team chose Google’s Android platform for this initial research because it is open source and it would give us freedom in our approach, including the ability to modify the mobile device’s operating system itself. The research team concluded that a Privileged Application was the right approach, and the result was ODAMA. This project is an important piece of the work to secure the expanding use of mobile devices with our nation’s critical infrastructure.

  13. Pharmaceutical applications of dynamic mechanical thermal analysis.

    PubMed

    Jones, David S; Tian, Yiwei; Abu-Diak, Osama; Andrews, Gavin P

    2012-04-01

    The successful development of polymeric drug delivery and biomedical devices requires a comprehensive understanding of the viscoleastic properties of polymers as these have been shown to directly affect clinical efficacy. Dynamic mechanical thermal analysis (DMTA) is an accessible and versatile analytical technique in which an oscillating stress or strain is applied to a sample as a function of oscillatory frequency and temperature. Through cyclic application of a non-destructive stress or strain, a comprehensive understanding of the viscoelastic properties of polymers may be obtained. In this review, we provide a concise overview of the theory of DMTA and the basic instrumental/operating principles. Moreover, the application of DMTA for the characterization of solid pharmaceutical and biomedical systems has been discussed in detail. In particular we have described the potential of DMTA to measure and understand relaxation transitions and miscibility in binary and higher-order systems and describe the more recent applications of the technique for this purpose.

  14. Manufacturing in space: Fluid dynamics numerical analysis

    NASA Technical Reports Server (NTRS)

    Robertson, S. J.; Nicholson, L. A.; Spradley, L. W.

    1981-01-01

    Natural convection in a spherical container with cooling at the center was numerically simulated using the Lockheed-developed General Interpolants Method (GIM) numerical fluid dynamic computer program. The numerical analysis was simplified by assuming axisymmetric flow in the spherical container, with the symmetry axis being a sphere diagonal parallel to the gravity vector. This axisymmetric spherical geometry was intended as an idealization of the proposed Lal/Kroes growing experiments to be performed on board Spacelab. Results were obtained for a range of Rayleigh numbers from 25 to 10,000. For a temperature difference of 10 C from the cooling sting at the center to the container surface, and a gravitional loading of 0.000001 g a computed maximum fluid velocity of about 2.4 x 0.00001 cm/sec was reached after about 250 sec. The computed velocities were found to be approximately proportional to the Rayleigh number over the range of Rayleigh numbers investigated.

  15. Rapid Analysis and Time Interval Deconvolution for Comprehensive Fuel Compound Group Classification and Speciation Using Gas Chromatography-Vacuum Ultraviolet Spectroscopy.

    PubMed

    Walsh, Phillip; Garbalena, Manuel; Schug, Kevin A

    2016-11-15

    A time interval deconvolution (TID) method was devised to integrate a gas chromatography-vacuum ultraviolet (GC-VUV) data set in order to provide bulk characterization and speciation of finished gasoline samples. The method was demonstrated using a commercially available standard and tested on a series of ASTM gasoline proficiency samples. Very good correlation (R(2) ∼ 0.97-0.99) between GC-VUV and measurements using various ASTM methods was achieved. A key advantage of the TID method applied to GC-VUV data sets is that a large number of coelution events can be tolerated, resulting in significantly easier and faster separations, approximately 30 min in the case of gasoline. Methods for determining relative response factors, VUV reference libraries, and generalization to other types of complex samples are also discussed.

  16. Estimating the duration of speciation from phylogenies.

    PubMed

    Etienne, Rampal S; Morlon, Hélène; Lambert, Amaury

    2014-08-01

    Speciation is not instantaneous but takes time. The protracted birth-death diversification model incorporates this fact and predicts the often observed slowdown of lineage accumulation toward the present. The mathematical complexity of the protracted speciation model has barred estimation of its parameters until recently a method to compute the likelihood of phylogenetic branching times under this model was outlined (Lambert et al. ). Here, we implement this method and study using simulated phylogenies of extant species how well we can estimate the model parameters (rate of initiation of speciation, rate of extinction of incipient and good species, and rate of completion of speciation) as well as the duration of speciation, which is a combination of the aforementioned parameters. We illustrate our approach by applying it to a primate phylogeny. The simulations show that phylogenies often do not contain enough information to provide unbiased estimates of the speciation-initiation rate and the extinction rate, but the duration of speciation can be estimated without much bias. The estimate of the duration of speciation for the primate clade is consistent with literature estimates. We conclude that phylogenies combined with the protracted speciation model provide a promising way to estimate the duration of speciation.

  17. Simultaneous speciation analysis of inorganic arsenic, chromium and selenium in environmental waters by 3-(2-aminoethylamino) propyltrimethoxysilane modified multi-wall carbon nanotubes packed microcolumn solid phase extraction and ICP-MS.

    PubMed

    Peng, Hanyong; Zhang, Nan; He, Man; Chen, Beibei; Hu, Bin

    2015-01-01

    Speciation analysis of inorganic arsenic, chromium and selenium in environmental waters is of great significance for the monitoring of environmental pollution. In this work, 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS) functionalized multi-wall carbon nanotubes (MWCNTs) were synthesized and employed as the adsorbent for simultaneous speciation analysis of inorganic arsenic, chromium and selenium in environmental waters by microcolumn solid-phase extraction (SPE)-inductively coupled plasma mass spectrometry (ICP-MS). It was found that As(V), Cr(VI) and Se(VI) could be selectively adsorbed on the microcolumn packed with AAPTS-MWCNTs adsorbent at pH around 2.2, while As(III), Cr(III) and Se(IV) could not be retained at this pH and passed through the microcolumn directly. Total inorganic arsenic, chromium and selenium was determined after the oxidation of As(III), Cr(III) and Se(IV) to As(V), Cr(VI) and Se(VI) with 10.0 μmol L(-1) KMnO4. The assay of As(III), Cr(III) and Se(IV) was based on subtracting As(V), Cr(VI) and Se(VI) from the total As, Cr and Se, respectively. Under the optimized conditions, the detection limits of 15, 38 and 16 ng L(-1) with the relative standard deviations (RSDs) of 7.4, 2.4 and 6.2% (c=1 µg L(-1), n=7) were obtained for As(V), Cr(VI) and Se(VI), respectively. The developed method was validated by analyzing four Certified Reference Materials, rainwater, Yangtze River and East Lake waters. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Simultaneous Speciation of Arsenic, Selenium, and Chromium by HPLC-ICP-MS

    USGS Publications Warehouse

    Wolf, Ruth E.; Morman, Suzette A.; Morrison, Jean M.; Lamothe, Paul J.

    2008-01-01

    An adaptation of an analytical method developed for chromium speciation has been utilized for the simultaneous determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) species using high performance liquid chromatography (HPLC) separation with ICP-MS detection. Reduction of interferences for the determination of As, Se, and Cr by ICP-MS is a major consideration for this method. Toward this end, a Dynamic Reaction Cell (DRC) ICP-MS system was used to detect the species eluted from the chromatographic column. A variety of reaction cell gases and conditions may be utilized, and the advantages and limitations of the gases tested to date will be presented and discussed. The separation and detection of the As, Se, and Cr species of interest can be achieved using the same chromatographic conditions in less than 2 minutes by complexing the Cr(III) with EDTA prior to injection on the HPLC column. Practical aspects of simultaneous speciation analysis will be presented and discussed, including issues with HPLC sample vial contamination, standard and sample contamination, species stability, and considerations regarding sample collection and preservation methods. The results of testing to determine the method's robustness to common concomitant element and anion effects will also be discussed. Finally, results will be presented using the method for the analysis of a variety of environmental and geological samples including waters, soil leachates and simulated bio-fluid leachates.

  19. Dynamic modelling and analysis of space webs

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Baoyin, HeXi; Li, JunFeng

    2011-04-01

    Future space missions demand operations on large flexible structures, for example, space webs, the lightweight cable nets deployable in space, which can serve as platforms for very large structures or be used to capture orbital objects. The interest in research on space webs is likely to increase in the future with the development of promising applications such as Furoshiki sat-ellite of JAXA, Robotic Geostationary Orbit Restorer (ROGER) of ESA and Grapple, Retrieve And Secure Payload (GRASP) of NASA. Unlike high-tensioned nets in civil engineering, space webs may be low-tensioned or tensionless, and extremely flexible, owing to the microgravity in the orbit and the lack of support components, which may cause computational difficulties. Mathematical models are necessary in the analysis of space webs, especially in the conceptual design and evaluation for prototypes. A full three-dimensional finite element (FE) model was developed in this work. Trivial truss elements were adopted to reduce the computational complexity. Considering cable is a compression-free material and its tensile stiffness is also variable, we introduced the cable material constitutive relationship to work out an accurate and feasible model for prototype analysis and design. In the static analysis, the stress distribution and global deformation of the webs were discussed to get access to the knowledge of strength of webs with different types of meshes. In the dynamic analysis, special attention was paid to the impact problem. The max stress and global deformation were investigated. The simulation results indicate the interesting phenomenon which may be worth further research.

  20. Homoploid hybrid speciation in animals.

    PubMed

    Mavárez, Jesús; Linares, Mauricio

    2008-10-01

    Among animals, evidence for homoploid hybrid speciation (HHS, i.e. the creation of a hybrid lineage without a change in chromosome number) was limited until recently to the virgin chub, Gila seminuda, and some controversial data in support of hybrid status for the red wolf, Canis rufus. This scarcity of evidence, together with pessimistic attitudes among zoologists about the evolutionary importance of hybridisation, prompted the view that HHS is extremely rare among animals, especially as compared with plants. However, in recent years, the literature on animal HHS has expanded to include several new putative examples in butterflies, ants, flies and fishes. We argue that this evidence suggests that HHS is far more common than previously thought and use it to provide insights into some of the genetic and ecological aspects associated with this type of speciation among animals.

  1. Sensory drive in cichlid speciation.

    PubMed

    Maan, Martine E; Hofker, Kees D; van Alphen, Jacques J M; Seehausen, Ole

    2006-06-01

    The role of selection in speciation is a central yet poorly understood problem in evolutionary biology. The rapid radiations of extremely colorful cichlid fish in African lakes have fueled the hypothesis that sexual selection can drive species divergence without geographical isolation. Here we present experimental evidence for a mechanism by which sexual selection becomes divergent: in two sibling species from Lake Victoria, female mating preferences for red and blue male nuptial coloration coincide with their context-independent sensitivities to red and blue light, which in turn correspond to a difference in ambient light in the natural habitat of the species. These results suggest that natural selection on visual performance, favoring different visual properties in different spectral environments, may lead to divergent sexual selection on male nuptial coloration. This interplay of ecological and sexual selection along a light gradient may provide a mechanism of rapid speciation through divergent sensory drive.

  2. Passivhaus: indoor comfort and energy dynamic analysis.

    NASA Astrophysics Data System (ADS)

    Guida, Antonella; Pagliuca, Antonello; Cardinale, Nicola; Rospi, Gianluca

    2013-04-01

    The research aims to verify the energy performance as well as the indoor comfort of an energy class A+ building, built so that the sum of the heat passive contributions of solar radiation, transmitted through the windows, and the heat generated inside the building, are adeguate to compensate for the envelope loss during the cold season. The building, located in Emilia Romagna (Italy), was built using a wooden structure, an envelope realized using a pinewood sandwich panels (transmittance U = 0.250 W/m2K) and, inside, a wool flax insulation layer and thermal window frame with low-emissivity glass (U = 0524 W/m2K). The building design and construction process has followed the guidelines set by "CasaClima". The building has been modeled in the code of dynamic calculation "Energy Plus" by the Design Builder application and divided it into homogenous thermal zones, characterized by winter indoor temperature set at 20 ° (+ / - 1 °) and summer indoor temperature set at 26 ° (+ / - 1 °). It has modeled: the envelope, as described above, the "free" heat contributions, the air conditioning system, the Mechanical Ventilation system as well as home automation solutions. The air conditioning system is an heat pump, able to guarantee an optimization of energy consumption (in fact, it uses the "free" heat offered by the external environment for conditioning indoor environment). As regards the air recirculation system, it has been used a mechanical ventilation system with internal heat cross-flow exchanger, with an efficiency equal to 50%. The domotic solutions, instead, regard a system for the control of windows external screening using reeds, adjustable as a function of incident solar radiation and a lighting management system adjusted automatically using a dimmer. A so realized building meets the requirement imposed from Italian standard UNI/TS 11300 1, UNI/TS 11300 2 and UNI/TS 11300 3. The analysis was performed according to two different configurations: in "spontaneous

  3. Pattern dynamics analysis of seismic catalogs

    NASA Astrophysics Data System (ADS)

    Tiampo, K.; Rundle, J.; Klein, W.; McGinnis, S.; Posadas, A.; Fernàndez, J.; Luzòn, F.

    2003-04-01

    The historical earthquake record, while not complete, spans hundreds to thousands of years of human history. As a result, large, extended fault systems such as those in California are known to demonstrate complex space-time seismicity patterns, which include, but are not limited to, repetitive events, precursory activity and quiescence, and aftershock sequences ((Mogi, 1969; Keilis-Borok et al., 1980; Kanamori, 1981; Kagan and Jackson, 1992; Saleur et al., 1996; Ellsworth and Cole, 1997; Pollitz and Sacks, 1997; Bowman et al., 1998; Nanjo et al., 1998; Wyss and Wiemer, 1999). Although the characteristics of these patterns can be qualitatively described, a systematic quantitative analysis remains elusive (Kanamori, 1981; Turcotte, 1991; Geller et al., 1997). Here we describe a new technique, formulated based on new developments in the physical and theoretical understanding of these complex, nonlinear fault systems that isolates emergent regions of coherent, correlated seismicity (Bak and Tang, 1989; Rundle, 1989; Sornette and Sornette, 1989; Rundle and Klein, 1995; Sammis et al., 1996; 1997; Fisher et al., 1997; Jaume and Sykes, 1999; Rundle et al., 1999; Tiampo et al., 2002). Analysis of data taken prior to large events reveals that the appearance of the coherent correlated regions is often associated with the future occurrence of major earthquakes in the same areas or other tectonic mechanisms such as aseismic slip events (Tiampo et al., 2002). We proceed to detail this pattern dynamics methodology and then identify systematic space-time variations in the seismicity from several tectonic regions.

  4. Fusion metrics for dynamic situation analysis

    NASA Astrophysics Data System (ADS)

    Blasch, Erik P.; Pribilski, Mike; Daughtery, Bryan; Roscoe, Brian; Gunsett, Josh

    2004-08-01

    To design information fusion systems, it is important to develop metrics as part of a test and evaluation strategy. In many cases, fusion systems are designed to (1) meet a specific set of user information needs (IN), (2) continuously validate information pedigree and updates, and (3) maintain this performance under changing conditions. A fusion system"s performance is evaluated in many ways. However, developing a consistent set of metrics is important for standardization. For example, many track and identification metrics have been proposed for fusion analysis. To evaluate a complete fusion system performance, level 4 sensor management and level 5 user refinement metrics need to be developed simultaneously to determine whether or not the fusion system is meeting information needs. To describe fusion performance, the fusion community needs to agree on a minimum set of metrics for user assessment and algorithm comparison. We suggest that such a minimum set should include feasible metrics of accuracy, confidence, throughput, timeliness, and cost. These metrics can be computed as confidence (probability), accuracy (error), timeliness (delay), throughput (amount) and cost (dollars). In this paper, we explore an aggregate set of metrics for fusion evaluation and demonstrate with information need metrics for dynamic situation analysis.

  5. MODELING MONOMETHYLMERCURY AND TRIBUTYLTIN SPECIATION WITH EPA'S GEOCHEMICAL SPECIATION MODEL MINTEQA2

    EPA Science Inventory

    Given the complexity of the various, simultaneous (and competing) equilibrium reactions governing the speciation of ionic species in aquatic systems, EPA has developed and distributed the geochemical speciation model MINTEQA2 (Brown and Allison, 1987, Allison et al., 1991; Hydrog...

  6. MODELING MONOMETHYLMERCURY AND TRIBUTYLTIN SPECIATION WITH EPA'S GEOCHEMICAL SPECIATION MODEL MINTEQA2

    EPA Science Inventory

    Given the complexity of the various, simultaneous (and competing) equilibrium reactions governing the speciation of ionic species in aquatic systems, EPA has developed and distributed the geochemical speciation model MINTEQA2 (Brown and Allison, 1987, Allison et al., 1991; Hydrog...

  7. Thermal adaptation and ecological speciation.

    PubMed

    Keller, I; Seehausen, O

    2012-02-01

    Ecological speciation is defined as the emergence of reproductive isolation as a direct or indirect consequence of divergent ecological adaptation. Several empirical examples of ecological speciation have been reported in the literature which very often involve adaptation to biotic resources. In this review, we investigate whether adaptation to different thermal habitats could also promote speciation and try to assess the importance of such processes in nature. Our survey of the literature identified 16 animal and plant systems where divergent thermal adaptation may underlie (partial) reproductive isolation between populations or may allow the stable coexistence of sibling taxa. In many of the systems, the differentially adapted populations have a parapatric distribution along an environmental gradient. Isolation often involves extrinsic selection against locally maladapted parental or hybrid genotypes, and additional pre- or postzygotic barriers may be important. Together, the identified examples strongly suggest that divergent selection between thermal environments is often strong enough to maintain a bimodal genotype distribution upon secondary contact. What is less clear from the available data is whether it can also be strong enough to allow ecological speciation in the face of gene flow through reinforcement-like processes. It is possible that intrinsic features of thermal gradients or the genetic basis of thermal adaptation make such reinforcement-like processes unlikely but it is equally possible that pertinent systems are understudied. Overall, our literature survey highlights (once again) the dearth of studies that investigate similar incipient species along the continuum from initial divergence to full reproductive isolation and studies that investigate all possible reproductive barriers in a given system.

  8. Arsenic Speciation of Terrestrial Invertebrates

    SciTech Connect

    Moriarty, M.M.; Koch, I.; Gordon, R.A.; Reimer, K.J. ); )

    2009-07-01

    The distribution and chemical form (speciation) of arsenic in terrestrial food chains determines both the amount of arsenic available to higher organisms, and the toxicity of this metalloid in affected ecosystems. Invertebrates are part of complex terrestrial food webs. This paper provides arsenic concentrations and arsenic speciation profiles for eight orders of terrestrial invertebrates collected at three historical gold mine sites and one background site in Nova Scotia, Canada. Total arsenic concentrations, determined by inductively coupled plasma mass spectrometry (ICP-MS), were dependent upon the classification of invertebrate. Arsenic species were determined by high-performance liquid chromatography (HPLC) ICP-MS and X-ray absorption spectroscopy (XAS). Invertebrates were found by HPLC ICP-MS to contain predominantly arsenite and arsenate in methanol/water extracts, while XAS revealed that most arsenic is bound to sulfur in vivo. Examination of the spatial distribution of arsenic within an ant tissue highlighted the differences between exogenous and endogenous arsenic, as well as the extent to which arsenic is transformed upon ingestion. Similar arsenic speciation patterns for invertebrate groups were observed across sites. Trace amounts of arsenobetaine and arsenocholine were identified in slugs, ants, and spiders.

  9. Introducing Dynamic Analysis Using Malthus's Principle of Population.

    ERIC Educational Resources Information Center

    Pingle, Mark

    2003-01-01

    Declares the use of dynamic models is increasing in macroeconomics. Explains how to introduce dynamic models to students whose technical skills are modest or varied. Chooses Malthus's Principle of Population as a natural context for introducing dynamic analysis because it provides a method for reviewing the mathematical tools and theoretical…

  10. Spatially Resolved Sulfur Speciation in Urban Soils

    NASA Astrophysics Data System (ADS)

    Brettholle, M.; Gleber, S.-C.; Mekiffer, B.; Legnini, D.; McNulty, I.; Vogt, S.; Wessolek, G.; Thieme, J.

    2011-09-01

    A combination of x-ray microscopy, elemental mapping, and XANES spectroscopy at the K-absorption edge of sulfur was used to analyze the elemental and particulate composition of an urban soil loaded with building rubble from WWII, exemplarily from Berlin, Germany. This combination of element specific high-resolution microscopy with high spectral resolution capabilities allows for the determination of elemental composition as well as chemical speciation and is therefore well suited for the analysis of highly heterogeneous environmental samples. Different soil and debris constituents could be assigned to elemental distribution patterns within collected fluorescence maps, allowing for a detailed analysis of the sulfur pool and release from war debris in subsequent studies. A detailed understanding of this sulfur lixiviation is central to preserve urban water quality.

  11. Speciation of organotin in environmental sediment samples.

    PubMed

    Ceulemans, M; Slaets, S; Adams, F

    1998-07-01

    An optimized sample preparation procedure for organotin speciation in sediment samples has been applied to the analysis of sediments collected in the environment. The method is based on tropolone complexation of the ionic organotins, followed by extraction into a hexane-ethylacetate mixture and derivatization by NaBEt(4). The method was applied to the determination of organotin in various harbour, shipyard and dry-dock sediments in Belgium. Butyltin compounds were detected in all samples analyzed, often at high mg kg(-1) levels. A limited number of samples showed the presence of phenyltin compounds. Further, the method was adapted to the analysis of river sediments sampled from the vicinity of shipyards. Butyltin concentrations were detected at the microg kg(-1) level in the majority of samples.

  12. Speciation analysis of inorganic arsenic in river water by Amberlite IRA 910 resin immobilized in a polyacrylamide gel as a selective binding agent for As(V) in diffusive gradient thin film technique.

    PubMed

    Rolisola, Ana M C M; Suárez, Carlos A; Menegário, Amauri A; Gastmans, Didier; Kiang, Chang H; Colaço, Camila D; Garcez, Daniel L; Santelli, Ricardo E

    2014-09-07

    In this study, a method is proposed for the selective retention of As(V) using diffusive gradient in thin film (DGT) samplers containing a strongly basic anion exchange resin (Amberlite IRA 910) supported on a polyacrylamide gel. In addition, the total arsenic content is determined by ferrihydrite gel discs. Subsequently, the concentration of As(III) was obtained by determining the difference between the total As and As(V). DGT experiments showed linear accumulation of As(V) (up to 280 ng) until a deployment time of 8 h deployment (R(2) > 0.99). The retention of As(V) was appropriate (97.9-112.3%) between pH 5 and 9. For a solution with an ionic strength ranging from 0.001 to 0.05 mol L(-1), the As(V) uptake ranged from 90-120%. The proposed method was applied for the speciation of arsenic in river water. For the analysis of spiked samples collected at the Furnas stream, the recoveries of total arsenic content ranged between 103.9% and 118.8%. However, the recoveries of As(III) and As(V) were 43.3-75.2% and 147.3-153.4%, respectively. These differences were probably because of the oxidation of As(III) to As(V) during deployments. For spiked samples collected at the Ribeirão Claro, the recoveries of dissolved As(III), As(V) and As(T) were 103.1%, 108.0% and 106.3%, respectively. Thus, the DGT technique with Amberlite IRA 910 resin as the binding phase can be employed for the in situ redox speciation of inorganic arsenic.

  13. Dynamic analysis of news streams: institutional versus environmental effects.

    PubMed

    Dooley, Kevin; Corman, Steven

    2004-07-01

    Many societal phenomena are studied through analysis of their representation in media-related texts, such as news articles. The dynamics of such data reflect the phenomenon's underlying generative mechanism. Media artifacts are assumed to mirror the social activity occurring in the environment, thus observed dynamics are assumed to reflect environmental dynamics. The institutional mechanics of media production also affect the observed dynamics however. In this study we examine the extent to which institutional versus environmental effects explain the observed dynamics of media content, in particular focusing on semi-continuous "news streams". We examine the dynamics of news streams produced by the electronic news organization Reuters, immediately following the events of September 11, 2001. We find that many of the observed dynamics appear institutionally generated. We conclude with methodological suggestions concerning the dynamic analysis of media content.

  14. Enabling in-situ observation of organic aerosol speciated composition: Advances in TAG instrumentation (Invited)

    NASA Astrophysics Data System (ADS)

    Goldstein, A. H.; Worton, D. R.; Zhao, Y.; Kreisberg, N. M.; Teng, A. P.; Hering, S. V.; Gorecki, T.; Ranjan, M.; Hennigan, C. J.; Lambe, A.; Nguyen, N.; Donahue, N. M.; Robinson, A. L.; Jayne, J. T.; Williams, B. J.; Worsnop, D. R.

    2009-12-01

    The complex chemical composition of atmospheric aerosols, particularly the organic carbon portion, presents unique measurement challenges. We developed the Thermal Desorption Aerosol Gas chromatograph (TAG) system for hourly in-situ speciation of a wide range of primary and secondary organic compounds in aerosols. This instrument combines an impactor particle collector with thermal desorption followed by gas chromatography and mass spectrometric detection to provide separation, identification, and quantification of organic constituents at the molecular level. Observed compounds include alkanes, aldehydes, ketones, PAHs, monocarboxylic acids, and many more. The hourly time resolution measurements provided by TAG capture dynamic and frequent changes in aerosol composition that would not be resolved using traditional filter collection. TAG measurements also provide a much larger data set, facilitating the use of statistical approaches such as positive matrix factorization to identify source categories and their contributions to the total observed aerosol. Because TAG identifies organic compounds at the molecular level, it can build on the extensive work obtained by traditional GC/MS analysis of filter samples on source emission profiles and secondary organic aerosol formation. We report here continued developments in the capabilities of our TAG system. Most recently, we have incorporated a two-dimensional chromatography (GC×GC) capability into TAG, and now have that instrument operating with a time of flight (TOF) MS detector. Two-dimensional chromatography provides two types of compound separation, most typically by volatility and polarity. It uses two columns with different stationary phases connected in series separated by a modulator. The modulator periodically traps analytes eluting from the first column, and injects fractions of this effluent onto the second column in the form of narrow pulses providing additional separation for co-eluting peaks. The approach

  15. Engine dynamic analysis with general nonlinear finite element codes

    NASA Technical Reports Server (NTRS)

    Adams, M. L.; Padovan, J.; Fertis, D. G.

    1991-01-01

    A general engine dynamic analysis as a standard design study computational tool is described for the prediction and understanding of complex engine dynamic behavior. Improved definition of engine dynamic response provides valuable information and insights leading to reduced maintenance and overhaul costs on existing engine configurations. Application of advanced engine dynamic simulation methods provides a considerable cost reduction in the development of new engine designs by eliminating some of the trial and error process done with engine hardware development.

  16. Size exclusion chromatography with evaporative light scattering detection as a method for speciation analysis of polydimethylsiloxanes. II. Validation of the method for analysis of pharmaceutical formulations.

    PubMed

    Mojsiewicz-Pieńkowska, Krystyna

    2011-12-05

    The aim of this study was to demonstrate the usefulness of the size exclusion chromatography with evaporative light scattering detection (SEC-ELSD) method in the identification and quantitative analysis of polydimethylsiloxanes (PDMS). The process of validation for the method was conducted, and the values obtained were compared with the acceptance criteria. Particularly important was the conclusion that SEC-ELSD method showed a high specificity for PDMS. PDMS is an organosilicon polymer and for this reason, it does not exist as a concrete chemical species. Depending on the length of the chain, PDMS can be toxic for organism. So far, the SEC-ELSD method has not been applied for the control of pharmaceutical products containing such PDMS as dimeticone or simeticone. The safety of use and effectiveness of such pharmaceutical products relies on the control of their quality. Therefore, the analytical methods and procedures that meet acceptance criteria for qualitative and quantitative analysis of the PDMS should be used. In the case of the analysis of pharmaceutical products, the acceptance criteria are established and recommended by, for example, the Pharmacopoeias, the U.S. Food and Drug Administration (FDA), the International Conference on Harmonisation (ICH) and the World Health Organization (WHO). The progress of knowledge, however, requires the development of new analytical tools which are able to solve incoming problems. In the case of pharmaceutical formulations containing PDMS, which are used not only by adults but also by children, it is necessary to use analytical methods which are characterized by a high specificity.

  17. Speciation of Iberian diving beetles in Pleistocene refugia (Coleoptera, Dytiscidae).

    PubMed

    Ribera, Ignacio; Vogler, Alfried P

    2004-01-01

    The Mediterranean basin is an area of high diversity and endemicity, but the age and origin of its fauna are still largely unknown. Here we use species-level phylogenies based on approximately 1300 base pairs of the genes 16S rRNA and cytochrome oxidase I to establish the relationships of 27 of the 34 endemic Iberian species of diving beetles in the family Dytiscidae, and to investigate their level of divergence. Using a molecular clock approach, 18-19 of these species were estimated to be of Pleistocene origin, with four to six of them from the Late Pleistocene ( approximately 100 000 years). A second, lower speciation frequency peak was assigned to Late Miocene or Early Pliocene. Analysis of the distributional ranges showed that endemic species placed in the tip nodes of the trees are significantly more likely to be allopatric with their sisters than endemic species at lower node levels. Allopatric sister species are also significantly younger than sympatric clades, in agreement with an allopatric mode of speciation and limited subsequent range movement. These results strongly suggest that for some taxa Iberian populations were isolated during the Pleistocene long enough to speciate, and apparently did not expand their ranges to recolonize areas north of the Pyrenees. This is in contradiction to observations from fossil beetles in areas further north, which document large range movements associated with the Pleistocene glacial cycles hypothesized to suppress population isolation and allopatric speciation.

  18. Chiral speciation of selenoamino acids in biological samples.

    PubMed

    Chen, Beibei; He, Man; Zhong, Cheng; Hu, Bin

    2014-10-10

    In this paper, the "state of the art" of chiral speciation of selenoamino acids (SeAAs) in biological samples is critically reviewed. The significance and the features of such studies are highlighted. A special focus lies on chiral speciation of SeAAs by hyphenation techniques in which a chiral separation method (such as gas chromatography (GC), high performance liquid chromatography (HPLC) and capillary electrophoresis (CE)) is on-line coupled with an elemental specific detector, especially inductively coupled plasma mass spectrometry (ICP-MS). The advances in the development and application of hyphenation techniques in chiral speciation of SeAAs in biological samples are summarized and a perspective for future developments including sophisticated and innovative applications is discussed. Overall, HPLC-ICP-MS is more applicable than GC/CE-ICP-MS for chiral speciation of SeAAs. In the future, more novel chiral HPLC methods with high enantio-resolution, low cost and robustness, and their more applications in real biological samples analysis are expected.

  19. Reconstructing the history of selection during homoploid hybrid speciation.

    PubMed

    Karrenberg, Sophie; Lexer, Christian; Rieseberg, Loren H

    2007-06-01

    This study aims to identify selection pressures during the historical process of homoploid hybrid speciation in three Helianthus (sunflower) hybrid species. If selection against intrinsic genetic incompatibilities (fertility selection) or for important morphological/ecological traits (phenotypic selection) were important in hybrid speciation, we would expect this selection to have influenced the parentage of molecular markers or chromosomal segments in the hybrid species' genomes. To infer past selection, we compared the parentage of molecular markers in high-density maps of the three hybrid species with predicted marker parentage from an analysis of fertility selection in artificial hybrids and from the directions of quantitative trait loci effects with respect to the phenotypes of the hybrid species. Multiple logistic regression models were consistent with both fertility and phenotypic selection in all three species. To further investigate traits under selection, we used a permutation test to determine whether marker parentage predicted from groups of functionally related traits differed from neutral expectations. Our results suggest that trait groups associated with ecological divergence were under selection during hybrid speciation. This study presents a new method to test for selection and supports earlier claims that fertility selection and phenotypic selection on ecologically relevant traits have operated simultaneously during sunflower hybrid speciation.

  20. Subspace dynamic mode decomposition for stochastic Koopman analysis

    NASA Astrophysics Data System (ADS)

    Takeishi, Naoya; Kawahara, Yoshinobu; Yairi, Takehisa

    2017-09-01

    The analysis of nonlinear dynamical systems based on the Koopman operator is attracting attention in various applications. Dynamic mode decomposition (DMD) is a data-driven algorithm for Koopman spectral analysis, and several variants with a wide range of applications have been proposed. However, popular implementations of DMD suffer from observation noise on random dynamical systems and generate inaccurate estimation of the spectra of the stochastic Koopman operator. In this paper, we propose subspace DMD as an algorithm for the Koopman analysis of random dynamical systems with observation noise. Subspace DMD first computes the orthogonal projection of future snapshots to the space of past snapshots and then estimates the spectra of a linear model, and its output converges to the spectra of the stochastic Koopman operator under standard assumptions. We investigate the empirical performance of subspace DMD with several dynamical systems and show its utility for the Koopman analysis of random dynamical systems.

  1. Mathematical treatment of isotopologue and isotopomer speciation and fractionation in biochemical kinetics

    NASA Astrophysics Data System (ADS)

    Maggi, Federico; Riley, William J.

    2010-03-01

    We present a mathematical treatment of the kinetic equations that describe isotopologue and isotopomer speciation and fractionation during enzyme-catalyzed biochemical reactions. These equations, presented here with the name GEBIK (general equations for biochemical isotope kinetics) and GEBIF (general equations for biochemical isotope fractionation), take into account microbial biomass and enzyme dynamics, reaction stoichiometry, isotope substitution number, and isotope location within each isotopologue and isotopomer. In addition to solving the complete GEBIK and GEBIF, we also present and discuss two approximations to the full solutions under the assumption of biomass-free and enzyme steady-state, and under the quasi-steady-state assumption as applied to the complexation rate. The complete and approximate approaches are applied to observations of biological denitrification in soils. Our analysis highlights that the full GEBIK and GEBIF provide a more accurate description of concentrations and isotopic compositions of substrates and products throughout the reaction than do the approximate forms. We demonstrate that the isotopic effects of a biochemical reaction depend, in the most general case, on substrate and complex concentrations and, therefore, the fractionation factor is a function of time. We also demonstrate that inverse isotopic effects can occur for values of the fractionation factor smaller than 1, and that reactions that do not discriminate isotopes do not necessarily imply a fractionation factor equal to 1.

  2. Interacting dark energy: Dynamical system analysis

    NASA Astrophysics Data System (ADS)

    Golchin, Hanif; Jamali, Sara; Ebrahimi, Esmaeil

    We investigate the impacts of interaction between dark matter (DM) and dark energy (DE) in the context of two DE models, holographic (HDE) and ghost dark energy (GDE). In fact, using the dynamical system analysis, we obtain the cosmological consequence of several interactions, considering all relevant component of universe, i.e. matter (dark and luminous), radiation and DE. Studying the phase space for all interactions in detail, we show the existence of unstable matter-dominated and stable DE-dominated phases. We also show that linear interactions suffer from the absence of standard radiation-dominated epoch. Interestingly, this failure resolved by adding the nonlinear interactions to the models. We find an upper bound for the value of the coupling constant of the interaction between DM and DE as b < 0.57in the case of holographic model, and b < 0.61 in the case of GDE model, to result in a cosmological viable matter-dominated epoch. More specifically, this bound is vital to satisfy instability and deceleration of matter-dominated epoch.

  3. Analysis of uterine contractions: a dynamical approach.

    PubMed

    Nagarajan, R; Eswaran, H; Wilson, J D; Murphy, P; Lowery, C; Preissl, H

    2003-07-01

    The development of suitable techniques for quantifying mechanical and electrophysiological aspects of uterine contractions has been an active area of research. The uterus is a physiological system consisting of a large number of interacting muscle cells. The activity of these cells evolves with time, a trait characteristic of a dynamical system. While such complex physiological systems are non-linear by their very nature, whether this non-linearity is exhibited in the external recording is far from trivial. Traditional techniques such as spectral analysis have been used in the past, but these techniques implicitly assume that the process generating the contractions is linear and hence may be biased. In this tutorial review, a systematic approach using a hierarchy of surrogate algorithms is used to determine the nature of the process generating the contractions produced during labor. The results reveal that uterine contractions are probably generated by non-linear processes. The contraction segments were obtained through simultaneous recordings of the electrical and magnetic signals corresponding to the electrophysiological activity of the uterus and then analyzed. The electrical activity was recorded by placement of non-invasive electrodes onto the maternal abdomen and magnetic activity was recorded non-invasively using a superconducting quantum interference device (SQUID).

  4. A dynamic human motion: coordination analysis.

    PubMed

    Pchelkin, Stepan; Shiriaev, Anton S; Freidovich, Leonid B; Mettin, Uwe; Gusev, Sergei V; Kwon, Woong; Paramonov, Leonid

    2015-02-01

    This article is concerned with the generic structure of the motion coordination system resulting from the application of the method of virtual holonomic constraints (VHCs) to the problem of the generation and robust execution of a dynamic humanlike motion by a humanoid robot. The motion coordination developed using VHCs is based on a motion generator equation, which is a scalar nonlinear differential equation of second order. It can be considered equivalent in function to a central pattern generator in living organisms. The relative time evolution of the degrees of freedom of a humanoid robot during a typical motion are specified by a set of coordination functions that uniquely define the overall pattern of the motion. This is comparable to a hypothesis on the existence of motion patterns in biomechanics. A robust control is derived based on a transverse linearization along the configuration manifold defined by the coordination functions. It is shown that the derived coordination and control architecture possesses excellent robustness properties. The analysis is performed on an example of a real human motion recorded in test experiments.

  5. Hybridization Reveals the Evolving Genomic Architecture of Speciation

    PubMed Central

    Kronforst, Marcus R.; Hansen, Matthew E.B.; Crawford, Nicholas G.; Gallant, Jason R.; Zhang, Wei; Kulathinal, Rob J.; Kapan, Durrell D.; Mullen, Sean P.

    2014-01-01

    SUMMARY The rate at which genomes diverge during speciation is unknown, as are the physical dynamics of the process. Here, we compare full genome sequences of 32 butterflies, representing five species from a hybridizing Heliconius butterfly community, to examine genome-wide patterns of introgression and infer how divergence evolves during the speciation process. Our analyses reveal that initial divergence is restricted to a small fraction of the genome, largely clustered around known wing-patterning genes. Over time, divergence evolves rapidly, due primarily to the origin of new divergent regions. Furthermore, divergent genomic regions display signatures of both selection and adaptive introgression, demonstrating the link between microevolutionary processes acting within species and the origin of species across macroevolutionary timescales. Our results provide a uniquely comprehensive portrait of the evolving species boundary due to the role that hybridization plays in reducing the background accumulation of divergence at neutral sites. PMID:24183670

  6. Selenium speciation in soil and rice: influence of water management and Se fertilization.

    PubMed

    Li, Hua-Fen; Lombi, Enzo; Stroud, Jacqueline L; McGrath, Steve P; Zhao, Fang-Jie

    2010-11-24

    Rice (Oryza sativa) is the staple food for half of the world's population, but the selenium (Se) concentrations in rice grain are low in many rice-growing regions. This study investigated the effects of water management on the Se speciation dynamics in the soil solution and Se uptake and speciation in rice in a pot experiment. A control containing no Se or 0.5 mg kg(-1) of soil of selenite or selenate was added to the soil, and plants were grown under aerobic or flooded conditions. Flooding soil increased soluble Se concentration when no Se or selenite was added to the soil, but decreased it markedly when selenate was added. Selenate was the main species in the +selenate treatment, whereas selenite and selenomethionine selenium oxide were detected in the flooded soil solutions of the control and +selenite treatments. Grain Se concentration was 49% higher in the flooded than in the aerobic treatments without Se addition. In contrast, when selenate or selenite was added, the aerobically grown rice contained 25- and 2-fold, respectively, more Se in grain than the anaerobically grown rice. Analysis of Se in rice grain using enzymatic hydrolysis followed by HPLC-ICP-MS and in situ X-ray absorption near-edge structure (XANES) showed selenomethionine to be the predominant Se species. The study showed that selenate addition to aerobic soil was the most effective way to increase Se concentration in rice grain.

  7. Arsenic speciation in rice cereals for infants.

    PubMed

    Juskelis, Rima; Li, Wanxing; Nelson, Jenny; Cappozzo, Jack C

    2013-11-13

    The aim of this study was to conduct a survey of arsenic (As) content in rice cereals for infants. The analysis was based on the FDA Elemental Analysis Manual (EAM 4.11). An inductively coupled plasma mass spectrometer (ICP-MS) was used to determine total As. Due to the different toxicities of the chemical forms of arsenic, the ICP-MS coupled to a high-performance liquid chromatograph (HPLC) was used to perform As speciation. The total and speciated arsenic was determined in 31 different infant rice cereals sold in U.S. supermarkets. The mass fraction of total inorganic As (iAs; sum of arsenite As(III) and arsenate As(V)) concentrations ranged between 55.5 ± 1.3 and 158.0 ± 6.0 μg/kg. The average total arsenic and iAs concentrations in infant rice cereal were 174.4 and 101.4 μg/kg, respectively. There was no substantial difference in iAs levels between organic and conventional rice cereals. The mixed-grain rice cereal contained the least total (105 μg/kg) and inorganic arsenic (63 μg/kg). The major detected organoarsenical species was dimethylarsinic acid (DMA). Monomethylarsonic acid (MMA) was not detected, or only trace levels were found. Spiked sample percent recoveries for iAs, DMA, and MMA ranged from a low of 97.3% for iAs to a high of 115.0% for DMA. Results for speciated and total As in the National Institute of Standards and Technology standard reference material rice flour (NIST SRM 1568) were in good agreement with certified values. In the NIST SRM 1568 sample (n = 5) repeatability (%RSD) was 2.8% for iAs, 1.7% for DMA and species sum, and 5.3% for the total arsenic by As total method. The average percent mass balance was 99.9 ± 6.3% for the NIST SRM 1568 sample. This study provides new and much needed information on arsenic levels in rice-based infant cereals.

  8. A novel report of metallothioneins in fish bile: SDS-PAGE analysis, spectrophotometry quantification and metal speciation characterization by liquid chromatography coupled to ICP-MS.

    PubMed

    Hauser-Davis, Rachel Ann; Gonçalves, Rodrigo Araújo; Ziolli, Roberta Lourenço; de Campos, Reinaldo Calixto

    2012-07-15

    Metallothioneins (MT) are a validated biomarker for metal exposure. In fish they are usually determined in the liver, while some studies have observed MT in kidney, muscle and gills. There are, however, no reports on MT in fish bile. This study aimed to verify if these proteins are present in fish bile, if they can be used as biomarkers for metal exposure and to characterize the metal speciation present in the different species. Three independent methods to verify MT presence in fish bile were conducted: 1D/2D gel electrophoresis, spectrophotometric analyses and SEC-HPLC-ICP-MS. Results show that all methods verified the presence of these proteins in fish bile, while SEC-HPLC-ICP-MS also characterized also characterized metals responsible for the contamination of the studied sites. Quantification was successfully conducted by two methods, densitometry (1D electrophoresis) and spectrophotometry, and the data indicates that bile MTs follow the same trend as in liver. Therefore, Biliary MT show the potential to be used the same way as MT from other matrices in metal exposure studies, with the advantage of being a simpler matrix and showing the possibility of not sacrificing the animals, as chronic duct cannulation is available. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Arsenic Speciation in Geothermal Waters

    NASA Astrophysics Data System (ADS)

    Keller, N. S.; Stefansson, A.; Sigfusson, B.

    2011-12-01

    Various arsenic species have been observed or inferred in geothermal waters in recent years, in particular thio- and oxyanions. However their exact stoechiometry and their oxidation state has been subjected to a sustained debate over the last decade. Most of the As species seen in geothermal waters are unstable under laboratory conditions, thus it is crucial that appropriate sampling and analytical techniques are used in order to minimise post-sampling changes. The goals of this study were to determine how many As species can be seen in geothermal systems and how geochemical parameters control the number and relative abundance of the species. Furthermore, we tested the stability of the As-S compounds after sampling, in particular whether the traditionally used flash-freezing method quantitatively preserves the species. Samples were collected from wells at the Hellisheidi Power Plant and from natural hot springs in the Geysir Geothermal Area in SW Iceland. The samples were analysed on-site immediately after sampling by first separating the various As species by Ion Chromatography followed by quantification by Hydride-Generation Atomic Fluorescence Spectrometer (HG-AFS). Preliminary results show that analysis of the samples immediately after sampling is crucial, as sample storage and flash-freezing/thawing appear to modify the As speciation. Using the retention times of the analytes through the chromatographic column, a minimum of seven As species were observed. Two of the species are oxides of AsIII and AsV, based on the comparison of their retention times with standards. The other five species have yet to be unequivocally identified, but based on prior studies it is assumed that at least some of them are thioarsenic species with various S:O ratios, with longer retention times for increasing S:O. Clear differences can be seen between samples from Hellisheidi and Geysir. In the case of the oxyanions, only AsIII is present at Hellisheidi whereas both oxidation states

  10. Advances in the Determination of the Speciation of the Carbon Associated with Biogenic Silica Produced by Plants

    NASA Astrophysics Data System (ADS)

    Masion, A.; Alexandre, A. E.; Ziarelli, F.; Viel, S.; Santos, G.

    2016-12-01

    Biogenic silica resulting from the precipitation of dissolved Si through biological processes in plants, often contains small amounts of occluded organic carbon. These phases, called phytoliths, have a long persistence in soils, making them tracers of past conditions. In this context, the knowledge of the carbon speciation associated with phytoliths bears significant importance in examining the carbon dynamics in soils. With carbon concentrations as low as the 0.1% range, examining the nature of organic carbon remains very challenging, and available tools (e.g. pyrolysis) are often prone to serious artifacts. Recent improvements of microwave sources enabled the application of the Dynamic Nuclear Polarization (DNP) technique to NMR, thereby establishing a new non-destructive tool for the qualitative and quantitative determination of the carbon speciation. Applied to the analysis of phytoliths, this method showed the presence of carbons from different sources within the sample: About 20% of the signal correspond to carbohydrates, and are assigned to photosynthetic carbon; the marked alkyl, N-alkyl and carbonyl signals indicate a significant proportion of proteins. This is consistent with the hypothesis that parts of the carbon associated with the phytoliths is imported into the host plant via uptake from the soil. Finally, lignins, glomalin-like and/or humic-like compounds are minor species associated with biogenic silica. This speciation was obtained overnight with a DNP-NMR set-up with an excellent sensitivity (few tens of weight ppm); the same spectrum on a standard NMR spectrometer would have required at least 250 days of data acquisition. The considerable gain in sensitivity associated with the use of DNP now makes NMR a relevant technique for the analysis of environmental samples.

  11. Double symbolic joint entropy in nonlinear dynamic complexity analysis

    NASA Astrophysics Data System (ADS)

    Yao, Wenpo; Wang, Jun

    2017-07-01

    Symbolizations, the base of symbolic dynamic analysis, are classified as global static and local dynamic approaches which are combined by joint entropy in our works for nonlinear dynamic complexity analysis. Two global static methods, symbolic transformations of Wessel N. symbolic entropy and base-scale entropy, and two local ones, namely symbolizations of permutation and differential entropy, constitute four double symbolic joint entropies that have accurate complexity detections in chaotic models, logistic and Henon map series. In nonlinear dynamical analysis of different kinds of heart rate variability, heartbeats of healthy young have higher complexity than those of the healthy elderly, and congestive heart failure (CHF) patients are lowest in heartbeats' joint entropy values. Each individual symbolic entropy is improved by double symbolic joint entropy among which the combination of base-scale and differential symbolizations have best complexity analysis. Test results prove that double symbolic joint entropy is feasible in nonlinear dynamic complexity analysis.

  12. Nondestructive Speciation Depth Profiling of Complex TiOx Nanolayer Structures by Grazing Incidence X-ray Fluorescence Analysis and Near Edge X-ray Absorption Fine Structure Spectroscopy.

    PubMed

    Pollakowski, Beatrix; Beckhoff, Burkhard

    2015-08-04

    An important challenge of modern material science is the depth-sensitive and nondestructive analysis of the chemical binding state of complex structures consisting of multiple thin layers. In general, the correlation of the material functionality and underlying chemical and physical properties is the key question in view of directed device development, performance, and quality control. It has been shown that the combined method grazing incidence X-ray fluorescence analysis (GIXRF) and near edge X-ray absorption fine structure spectroscopy (NEXAFS) can significantly contribute to the nondestructive chemical analysis of buried thin films and interface structures regarding chemical speciation. Recently, we have enhanced the method to allow for a depth-resolved analysis of multilayered nanoscaled thin film structures. By means of appropriate model systems, the methodology has been developed and successfully validated. The model systems basically consist of a carbon cap layer, two titanium layers differing in their oxidation states and separated by a thin carbon layer, and a silicon substrate covered with molybdenum and a carbon layer. A differential approach has been developed to derive the chemical species of each of the titanium layers.

  13. Adaptive speciation theory: a conceptual review.

    PubMed

    Weissing, Franz J; Edelaar, Pim; van Doorn, G Sander

    2011-03-01

    Speciation-the origin of new species-is the source of the diversity of life. A theory of speciation is essential to link poorly understood macro-evolutionary processes, such as the origin of biodiversity and adaptive radiation, to well understood micro-evolutionary processes, such as allele frequency change due to natural or sexual selection. An important question is whether, and to what extent, the process of speciation is 'adaptive', i.e., driven by natural and/or sexual selection. Here, we discuss two main modelling approaches in adaptive speciation theory. Ecological models of speciation focus on the evolution of ecological differentiation through divergent natural selection. These models can explain the stable coexistence of the resulting daughter species in the face of interspecific competition, but they are often vague about the evolution of reproductive isolation. Most sexual selection models of speciation focus on the diversification of mating strategies through divergent sexual selection. These models can explain the evolution of prezygotic reproductive isolation, but they are typically vague on questions like ecological coexistence. By means of an integrated model, incorporating both ecological interactions and sexual selection, we demonstrate that disruptive selection on both ecological and mating strategies is necessary, but not sufficient, for speciation to occur. To achieve speciation, mating must at least partly reflect ecological characteristics. The interaction of natural and sexual selection is also pivotal in a model where sexual selection facilitates ecological speciation even in the absence of diverging female preferences. In view of these results, it is counterproductive to consider ecological and sexual selection models as contrasting and incompatible views on speciation, one being dominant over the other. Instead, an integrative perspective is needed to achieve a thorough and coherent understanding of adaptive speciation.

  14. Fast voltammetry of metals at carbon-fiber microelectrodes: towards an online speciation sensor.

    PubMed

    Pathirathna, Pavithra; Siriwardhane, Thushani; McElmurry, Shawn P; Morgan, Stephen L; Hashemi, Parastoo

    2016-11-14

    Speciation controls the chemical behavior of trace metals. Thus, there is great demand for rapid speciation analysis in a variety of fields. In this study, we describe the application of fast scan cyclic voltammetry (FSCV) and fast scan adsorption controlled voltammetry (FSCAV) to trace metal speciation analysis. We show that Cu(2+) can be detected using FSCAV in different matrices. We find that matrices with different Cu(2+) binding ability do not affect the equilibrium of Cu(2+) adsorption onto CFMs, and thus are an excellent predictor for free Cu(2+) ([Cu(2+)]free) in solution. We modelled a correlation between the FSCV response, [Cu(2+)]free and log Kf for 15 different Cu(2+) complexes. Using our model, we rapidly predicted, and verified [Cu(2+)]free and Kf of a real groundwater sample spiked with Cu(2+). We thus highlight the potential of fast voltammetry as a rapid trace metal speciation sensor.

  15. Application of Johnson et al.'s speciation threshold model to apparent colonization times of island biotas.

    PubMed

    Ricklefs, Robert E; Bermingham, Eldredge

    2004-08-01

    Understanding patterns of diversity can be furthered by analysis of the dynamics of colonization, speciation, and extinction on islands using historical information provided by molecular phylogeography. The land birds of the Lesser Antilles are one of the most thoroughly described regional faunas in this context. In an analysis of colonization times, Ricklefs and Bermingham (2001) found that the cumulative distribution of lineages with respect to increasing time since colonization exhibits a striking change in slope at a genetic distance of about 2% mitochondrial DNA sequence divergence (about one million years). They further showed how this heterogeneity could be explained by either an abrupt increase in colonization rates or a mass extinction event. Cherry et al. (2002), referring to a model developed by Johnson et al. (2000), argued instead that the pattern resulted from a speciation threshold for reproductive isolation of island populations from their continental source populations. Prior to this threshold, genetic divergence is slowed by migration from the source, and species of varying age accumulate at a low genetic distance. After the threshold is reached, source and island populations diverge more rapidly, creating heterogeneity in the distribution of apparent ages of island taxa. We simulated of Johnson et al.'s speciation-threshold model, incorporating genetic divergence at rate k and fixation at rate M of genes that have migrated between the source and the island population. Fixation resets the divergence clock to zero. The speciation-threshold model fits the distribution of divergence times of Lesser Antillean birds well with biologically plausible parameter estimates. Application of the model to the Hawaiian avifauna, which does not exhibit marked heterogeneity of genetic divergence, and the West Indian herpetofauna, which does, required unreasonably high migration-fixation rates, several orders of magnitude greater than the colonization rate. However

  16. Dynamical Analysis of Motorcycle by Multibody Dynamics Approach

    NASA Astrophysics Data System (ADS)

    Zhu, Shaopeng; Nishimura, Hidekazu; Iwamatsu, Shunsuke; Tajima, Hiroshi

    In this paper, a dynamical model of a motorcycle, which consists of four rigid bodies with nine degrees of freedom, is presented. In this model, the cross-sectional shape of the tire is described as a half-circle and its deformation is taken into account. By taking account of the tire slip condition or the tire nonslip condition in the longitudinal direction of the wheels, each equation of motion is derived. Also, by carrying out simulations, it is verified that the responses to the front steering impulsive torque are in good agreement with the results obtained using commercial software. Moreover, the longitudinal friction force and the lateral force in a turning maneuver are analyzed.

  17. Dynamic Analysis of Fuel Cycle Transitioning

    SciTech Connect

    Brent Dixon; Steve Piet; David Shropshire; Gretchen Matthern

    2009-09-01

    This paper examines the time-dependent dynamics of transitioning from a once-through fuel cycle to a closed fuel cycle. The once-through system involves only Light Water Reactors (LWRs) operating on uranium oxide fuel UOX), while the closed cycle includes both LWRs and fast spectrum reactors (FRs) in either a single-tier system or two-tier fuel system. The single-tier system includes full transuranic recycle in FRs while the two-tier system adds one pass of mixed oxide uranium-plutonium (MOX U-Pu) fuel in the LWR. While the analysis primarily focuses on burner fast reactors, transuranic conversion ratios up to 1.0 are assessed and many of the findings apply to any fuel cycle transitioning from a thermal once-through system to a synergistic thermal-fast recycle system. These findings include uranium requirements for a range of nuclear electricity growth rates, the importance of back end fuel cycle facility timing and magnitude, the impact of employing a range of fast reactor conversion ratios, system sensitivity to used fuel cooling time prior to recycle, impacts on a range of waste management indicators, and projected electricity cost ranges for once-through, single-tier and two-tier systems. The study confirmed that significant waste management benefits can be realized as soon as recycling is initiated, but natural uranium savings are minimal in this century. The use of MOX in LWRs decouples the development of recycle facilities from fast reactor fielding, but also significantly delays and limits fast reactor deployment. In all cases, fast reactor deployment was significantly below than predicted by static equilibrium analyses.

  18. Mercury speciation in floodplain soils and sediments along a contaminated river transect

    SciTech Connect

    Wallschlaeger, D.; Desai, M.V.M.; Spengler, M.; Wilken, R.D.

    1998-09-01

    A novel mercury-specific sequential extraction procedure (SEP) for the assessment of mercury (Hg) speciation in soils and sediments, with emphasis on studying the interaction between Hg and organic matter (OM), was developed and tested. It was applied to determine Hg speciation in floodplain topsoils and surface sediments along the Hg-contaminated part of the river Elbe, and to simultaneously derive some information on the (re)mobilization potentials for Hg from these matrices. The majority of the total Hg in the ecosystem today is bound in the floodplains, which also still geographically reflect the historic emission record. Most of the Hg in both matrices is bound strongly to OM, suggesting low availability. However, distinct differences between Hg speciation in the floodplain soils and sediments were also discovered. Mercury deposited in the floodplains shows speciation patterns that indicate stronger fixation compared with Hg in the sediments. This difference is attributed to the association of Hg with larger quantities of OM, which presumably also has higher molecular weight (MW). By comparison, Hg in the sediments was distributed among weaker binding forms, which are more likely to liberate Hg. Particularly, sediments showed a total lack of sulfidic binding forms for Hg. Pronounced geographical trends were detected in the Hg speciation along the river transect, with a general downstream shift from weaker to stronger binding forms, probably due to increased association with OM. These studies indicate that Hg speciation in riverine ecosystems is dynamic and reflects the chemical mechanisms underlying (bio) geochemical processes like distribution and transport.

  19. Arrhythmic dynamics from singularity analysis of electrocardiographic maps.

    PubMed

    Pont, Oriol; Yahia, Hussein; Xu, Binbin

    2013-01-01

    From a point view of nonlinear dynamics, the electrical activity of the heart is a complex dynamical system, whose dynamics reflects the actual state of health of the heart. Nonlinear signal-processing methods are needed in order to accurately characterize these signals and improve understanding of cardiac arrhythmias. Recent developments on reconstructible signals and multiscale information content show that an analysis in terms of singularity exponents provides compact and meaningful descriptors of the structure and dynamics of the system. Such approach gives a compact representation atrial arrhythmic dynamics, which can sharply highlight regime transitions and arrhythmogenic areas.

  20. Speciation in fungal and oomycete plant pathogens

    USDA-ARS?s Scientific Manuscript database

    The process of speciation by definition involves evolution of one or more reproductive isolating mechanisms that split a single species into two that can no longer interbreed. Determination of which processes are responsible for speciation is important yet challenging. Several studies have proposed ...

  1. Static and Dynamics of a Pump Impeller with a Balancing Device Part II: Dynamic Analysis

    NASA Astrophysics Data System (ADS)

    Martsinkovsky, V. A.; Zhulyov, A.; Kundera, C.

    2014-08-01

    This paper presents the theoretical study of the system comprising an impeller and a balancing device. It deals with the dynamic analysis of the system, i.e., the axial vibrations of the impeller, and the system stability. The dynamic analysis took into account linearized hydrodynamic forces and moments generated in the longitudinal clearances of the seals of the impeller. The theoretical analysis was supplemented with a numerical example with characteristics determined for a real single-stage centrifugal pump

  2. Evaluation of a pulsed glow discharge time-of-flight mass spectrometer as a detector for gas chromatography and the influence of the glow discharge source parameters on the information volume in chemical speciation analysis.

    PubMed

    Fliegel, Daniel; Fuhrer, Katrin; Gonin, Marc; Günther, Detlef

    2006-09-01

    The figures of merit of a pulsed glow discharge time-of-flight mass spectrometer (GD-TOFMS) as a detector for gas chromatography (GC) analysis were evaluated. The mass resolution for the GD-TOFMS was determined on FWHM in the high mass range (208Pb+) as high as 5,500. Precision of 400 subsequent analyses was calculated on 63Cu+ to be better than 1% RSD with no significant drift over the time of the analysis. Isotope precision based on the 63Cu+/65Cu+ ratio over 400 analyses was 1.5% RSD. The limits of detection for gaseous analytes (toluene in methanol as solvent) were determined to be as low as several hundred ppb or several hundred pg absolute without using any pre-concentration technique. Furthermore, the different GD source parameters like capillary distance, cathode-anode spacing, and GD source pressure with regards to the accessible elemental, structural, and molecular information were evaluated. It was demonstrated that each of these parameters has severe influence on the ratio of elemental, structural, and parent molecular information in chemical speciation analysis.

  3. Numerical Analysis of Constrained Dynamical Systems, with Applications to Dynamic Contact of Solids, Nonlinear Elastodynamics and Fluid-Structure Interactions

    DTIC Science & Technology

    2000-12-01

    NUMERICAL ANALYSIS OF CONSTRAINED DYNAMICAL SYSTEMS, WITH APPLICATIONS TO DYNAMIC CONTACT OF SOLIDS, NONLINEAR ELASTODYNAMICS AND FLUID-STRUCTURE...2000 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Numerical Analysis of Constrained Dynamical Systems, with 5b. GRANT NUMBER Applications to Dynamic...This extension allows the analysis of fluid-structure interfaces through the Lagrangian contact logic previously developed. Similarly, we have developed

  4. Metal speciation and toxicity of Tamar Estuary water to larvae of the Pacific oyster, Crassostrea gigas.

    PubMed

    Money, Cathryn; Braungardt, Charlotte B; Jha, Awadhesh N; Worsfold, Paul J; Achterberg, Eric P

    2011-07-01

    As part of the PREDICT Tamar Workshop, the toxicity of estuarine waters in the Tamar Estuary (southwest England) was assessed by integration of metal speciation determination with bioassays. High temporal resolution metal speciation analysis was undertaken in situ by deployment of a Voltammetric In situ Profiling (VIP) system. The VIP detects Cd (cadmium), Pb (lead) and Cu (copper) species smaller than 4 nm in size and this fraction is termed 'dynamic' and considered biologically available. Cadmium was mainly present in the dynamic form and constituted between 56% and 100% of the total dissolved concentration, which was determined subsequently in the laboratory in filtered discrete samples. In contrast, the dynamic Pb and Cu fractions were less important, with a much larger proportion of these metals associated with organic ligands and/or colloids (45-90% Pb and 46-85% Cu), which probably reduced the toxicological impact of these elements in this system. Static toxicity tests, based on the response of Crassostrea gigas larva exposed to discrete water samples showed a high level of toxicity (up to 100% abnormal development) at two stations in the Tamar, particularly during periods of the tidal cycle when the influence of more pristine coastal water was at its lowest. Competitive ligand-exchange Cu titrations showed that natural organic ligands reduced the free cupric ion concentration to levels that were unlikely to have been the sole cause of the observed toxicity. Nonetheless, it is probable that the combined effect of the metals determined in this work contributed significantly to the bioassay response.

  5. Evolutionary history of the four-spotted megrim ( Lepidorhombus boscii) and speciation time within the genus based on mitochondrial genes analysis

    NASA Astrophysics Data System (ADS)

    Campo, Daniel; Garcia-Vazquez, Eva

    2010-10-01

    The evolutionary history and geographic distribution of North-Atlantic and Mediterranean marine taxa has been largely affected by past geological and climatic events, like the Messinian salinity crisis, the opening of the Strait of Gibraltar and the Quaternary glacial cycles. The four-spotted megrim Lepidorhombus boscii is a demersal flatfish of the family Scophthalmidae (Pleuronectiformes), distributed in the Northeast Atlantic and the Mediterranean Sea. During its larval development it is planktonic, being passively drifted by marine currents, while adults are more or less sedentary living near the sea bottom. In order to investigate whether past geological and climatic events have influenced the evolutionary and demographic history of L.boscii, we analyzed a fragment of the highly variable mitochondrial control region in 163 individuals from different North-Atlantic areas and from the Mediterranean Sea. Contemporary processes of moderate gene flow, partially restricted by isolation by distance, as well as recent paleoecological events like the last Pleistocene glaciation, seem to play key roles in shaping the current phylogeographic pattern of the four-spotted megrim. On the other hand, we also analyzed 94 individuals from different North-Atlantic areas of its congeneric species L. whiffiagonis in order to compare genetic variation patterns within this genus. Finally, we used a fragment of the protein-coding mitochondrial gene cytochrome c oxidase I to estimate the time of speciation in megrims. Results suggest that divergence between the two species likely took place 5.3 MYA, which can be correlated with the end of the Messinian salinity crisis.

  6. Redox speciation analysis of dissolved iron in estuarine and coastal waters with on-line solid phase extraction and graphite furnace atomic absorption spectrometry detection.

    PubMed

    Chen, Yaojin; Feng, Sichao; Huang, Yongming; Yuan, Dongxing

    2015-05-01

    An automatic on-line solid phase extraction (SPE) system employing the flow injection (FI) technique directly coupled to a graphite furnace atomic absorption spectrometer (GFAAS) was established for speciation and determination of dissolved iron in estuarine and coastal waters. Fe(II) was mixed with ferrozine solution in a sample stream to form the Fe(II)-ferrozine complex which was extracted onto a C18 SPE cartridge, eluted with eluent and detected with GFAAS. In a parallel flow channel, Fe(III) was reduced to Fe(II) with ascorbic acid and then detected in the same way as Fe(II). The home-made interface between FI-SPE and GFAAS efficiently realized the sample introduction to the furnace in a semi-automated way. Parameters of the FI-SPE system and graphite furnace program were optimized based on a univariate experimental design and an orthogonal array design. The salinity effect on the method sensitivity was investigated. The proposed method provided a detection limit of 1.38 nmol L(-1) for Fe(II) and 1.87 nmol L(-1) for Fe(II+III). With variation of the sample loading volume, a broadened determination range of 2.5-200 nmol L(-1) iron could be obtained. The proposed method was successfully applied to analyze iron species in samples collected from the Jiulongjiang Estuary, Fujian, China. With the 2-cartridge FI-SPE system developed, on-line simultaneous determination of Fe species with GFAAS was achieved for the first time.

  7. Speciation analysis of selenium metabolites in urine and breath by HPLC- and GC-inductively coupled plasma-MS after administration of selenomethionine and methylselenocysteine to rats.

    PubMed

    Ohta, Yuki; Kobayashi, Yayoi; Konishi, Sakae; Hirano, Seishiro

    2009-11-01

    Selenium is an essential trace element found in vegetables as selenomethionine (SeMet) and methylselenocysteine (MeSeCys). In the present study, we used stable isotopes of Se to investigate differences between how SeMet and MeSeCys are metabolized, using methylseleninic acid (MSA) as a reference methylselenol source. A mixture containing (76)Se-SeMet, (77)Se-MeSeCys, and (82)Se-MSA (each 25 microg Se/kg b.w.) was orally administered to rats, and then, speciation analyses of Se in urine and exhaled gas were conducted using HPLC-inductively coupled plasma (ICP)-MS and GC-ICP-MS, respectively. The proportions of (76)Se-, (77)Se-, and (82)Se-selenosugar (Se-sugar) to total urinary Se metabolites originating from each tracer were very similar, while the proportion of (77)Se-tirmethylselenonium (TMSe) was much less than that of(76)Se- and (82)Se-TMSe in urine, suggesting that(77)Se-SeMet is less efficiently metabolized to TMSe. Similarly, there was significantly less (77)Se-dimethylselenide (DMSe) originating from (77)Se-SeMet than(76)Se- and (82)Se-DMSe originating from (76)Se-MeSeCys and (82)Se-MSA in exhaled gas. It is generally accepted that DMSe and TMSe are metabolites of methylselenol, a putative metabolic intermediate in Se metabolism. Methylselenol is believed to be responsible for the cancer chemoprevention effects of Se. These results suggest that MeSeCys is converted to methylselenol more efficiently than is SeMet and that urinary TMSe and exhaled DMSe might be useful biomarkers for the generation of cancer chemopreventive forms of Se.

  8. Rates of speciation in the fossil record

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1998-01-01

    Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges.

  9. Rates of speciation in the fossil record.

    PubMed Central

    Sepkoski, J J

    1998-01-01

    Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges. PMID:11541734

  10. Rates of speciation in the fossil record

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1998-01-01

    Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges.

  11. Visibility graph analysis on heartbeat dynamics of meditation training

    NASA Astrophysics Data System (ADS)

    Jiang, Sen; Bian, Chunhua; Ning, Xinbao; Ma, Qianli D. Y.

    2013-06-01

    We apply the visibility graph analysis to human heartbeat dynamics by constructing the complex networks of heartbeat interval time series and investigating the statistical properties of the network before and during chi and yoga meditation. The experiment results show that visibility graph analysis can reveal the dynamical changes caused by meditation training manifested as regular heartbeat, which is closely related to the adjustment of autonomous neural system, and visibility graph analysis is effective to evaluate the effect of meditation.

  12. Speciation and distribution of cadmium and lead in salinized horizons of antrosols

    NASA Astrophysics Data System (ADS)

    Bulgariu, D.; Bulgariu, L.; Astefanei, D.

    2009-04-01

    The utilization of intensive technologies for the vegetable cultivation in glass houses by the administration of high doses of organic fertilizes, the supra-dimensional irrigation and the maintaining of soil at high humidity state, in special in case of vicious drainage have as result the rapid degradation of morphological, chemical and physical characteristics of soils, concretized by: (i) decrease of structural aggregates stability; (ii) more dense packing of soil; (iii) accumulation of easy soluble salts (in special at superior horizons level); (iv) limitation of organic compounds and micro-elements biodisponibility. All these determined a significant reduction of productivity and of exploitation duration of soils from glass houses. These phenomena modified continuously the dynamic of speciation processes and inter-phases distribution, of heavy metals in soils from glass houses, and can determined a non-controlled accumulation of heavy metals, in special as mobile forms with high biodisponibility. Ours studied have been performed using soil profiles drawing from Copou-glass house, Iasi (Romania). Has been followed the modification of distribution for speciation forms of cadmium and lead (two heavy metals with high toxicity degree), between hortic antrosol horizons, and between chemical-mineralogical components of this, with the progressive salinization of superior horizons, in 2007-2008 period. The separation, differentiation and determination of cadmium and lead speciation forms was done by combined solid-liquid sequential extraction (SPE) and extraction in aqueous polymer-inorganic salt two-phase systems (ABS) procedure, presented in some of ours previous studies. After extraction, the total contents of the two heavy metals and fractions from these differential bonded by mineral and organic components of hortic antrosol have been determined by atomic absorption spectrometry. The specific interaction mechanisms of Cd and Pb with organic-mineral components of

  13. Dynamic analysis for robot arm control

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.

    1983-01-01

    Explicit state equations provide detailed analytic insight into the dynamic behavior of a robot arm and facilitate the understanding of the control problem. The analytic strength of explicit state equations is exemplified for a given robot arm. In fact, for the quoted example, the explicit and exact state equations involve considerably less computation than the use of the known most efficient general-purpose computational algorithm for robot arm dynamics.

  14. The speed of ecological speciation.

    PubMed

    Hendry, Andrew P; Nosil, Patrik; Rieseberg, Loren H

    2007-06-01

    Adaptation can occur on ecological time-scales (contemporary evolution) and adaptive divergence can cause reproductive isolation (ecological speciation). From the intersection of these two premises follows the prediction that reproductive isolation can evolve on ecological time-scales. We explore this possibility in theory and in nature. Finding few relevant studies, we examine each in some detail. THEORY: Several models have demonstrated that ecological differences can drive the evolution of partial reproductive barriers in dozens to hundreds of generations. Barriers likely to evolve quickly include dispersal rate, habitat preference and selection against migrants/hybrids. PLANTS: Adjacent populations adapting to different fertilizer treatments or to mine tailings can develop reproductive barriers within at least 100 generations. These barriers include differences in flowering time and selection against migrants/hybrids. INVERTEBRATES: Populations on native and introduced host plants can manifest reproductive barriers in dozens to hundreds of generations. These barriers include local host preference and selection against migrants/hybrids. VERTEBRATES: Salmon adapting to divergent breeding environments can show restricted gene flow within at least 14 generations. Birds evolving different migratory routes can mate assortatively within at least 10-20 generations. Hybrid sculpins can become isolated from their ancestral species within at least 20-200 generations. Ecological speciation can commence within dozens of generations. How far it goes is an important question for future research.

  15. The speed of ecological speciation

    PubMed Central

    HENDRY, ANDREW P.; NOSIL, PATRIK; RIESEBERG, LOREN H.

    2008-01-01

    Summary Adaptation can occur on ecological time-scales (contemporary evolution) and adaptive divergence can cause reproductive isolation (ecological speciation). From the intersection of these two premises follows the prediction that reproductive isolation can evolve on ecological time-scales. We explore this possibility in theory and in nature. Finding few relevant studies, we examine each in some detail. Theory Several models have demonstrated that ecological differences can drive the evolution of partial reproductive barriers in dozens to hundreds of generations. Barriers likely to evolve quickly include dispersal rate, habitat preference and selection against migrants/hybrids. Plants Adjacent populations adapting to different fertilizer treatments or to mine tailings can develop reproductive barriers within at least 100 generations. These barriers include differences in flowering time and selection against migrants/hybrids. Invertebrates Populations on native and introduced host plants can manifest reproductive barriers in dozens to hundreds of generations. These barriers include local host preference and selection against migrants/hybrids. Vertebrates Salmon adapting to divergent breeding environments can show restricted gene flow within at least 14 generations. Birds evolving different migratory routes can mate assortatively within at least 10–20 generations. Hybrid sculpins can become isolated from their ancestral species within at least 20–200 generations. Ecological speciation can commence within dozens of generations. How far it goes is an important question for future research. PMID:19096732

  16. Molecular models for actinide speciation

    SciTech Connect

    Clark, D.L.; Watkin, J.G.; Morris, D.E.; Berg, J.M.

    1994-06-01

    Much effort has been devoted to the development of sensitive spectroscopic techniques for the study of actinide speciation based on the sensitivity of f-f electronic absorption bands to oxidation state and ligation of the actinide ions. These efforts assume that data obtained in such studies will be interpretable in terms of changes in complexation of the metal center. However, the current understanding of 5f electronic structure is based on data from solid state doped single crystals. In those studies, the local coordination geometry about the central actinide ion is maintained in an almost perfect high-symmetry environment and will have little relevance for species in solution where deviations from perfect high symmetry tend to be the rule rather than the exception. The authors have developed a vigorous research program in the systematic preparation and spectroscopic characterization of synthetic actinide complexes (Th, U, Np, and Pu) in which they can control nuclearity, oxidation state, and molecular structure. These complexes have been used to determine how observable electronic transitions are perturbed in response to structural changes in the complex in solution. From the spectra obtained for these model complexes, the authors have found that the f-f transitions naturally fall into obvious groupings by coordination number and symmetry by which they can now differentiate between monomeric, dimeric, and trimeric species in solution. The study of radionuclide speciation is fundamentally important to the determination of radionuclide solubility in the groundwater at Yucca Mountain.

  17. Bird song, ecology and speciation.

    PubMed Central

    Slabbekoorn, Hans; Smith, Thomas B

    2002-01-01

    The study of bird song dialects was once considered the most promising approach for investigating the role of behaviour in reproductive divergence and speciation. However, after a series of studies yielding conflicting results, research in the field slowed significantly. Recent findings, on how ecological factors may lead to divergence in both song and morphology, necessitate a re-examination. We focus primarily on species with learned song, examine conflicting results in the literature and propose some potential new directions for future studies. We believe an integrative approach, including an examination of the role of ecology in divergent selection, is essential for gaining insight into the role of song in the evolution of assortative mating. Habitat-dependent selection on both song and fitness-related characteristics can lead to parallel divergence in these traits. Song may, therefore, provide females with acoustic cues to find males that are most fit for a particular habitat. In analysing the role of song learning in reproductive divergence, we focus on post-dispersal plasticity in a conceptual framework. We argue that song learning may initially constrain reproductive divergence, while in the later stages of population divergence it may promote speciation. PMID:12028787

  18. Development of methodology for horizontal axis wind turbine dynamic analysis

    NASA Technical Reports Server (NTRS)

    Dugundji, J.

    1982-01-01

    Horizontal axis wind turbine dynamics were studied. The following findings are summarized: (1) review of the MOSTAS computer programs for dynamic analysis of horizontal axis wind turbines; (2) review of various analysis methods for rotating systems with periodic coefficients; (3) review of structural dynamics analysis tools for large wind turbine; (4) experiments for yaw characteristics of a rotating rotor; (5) development of a finite element model for rotors; (6) development of simple models for aeroelastics; and (7) development of simple models for stability and response of wind turbines on flexible towers.

  19. Selenium speciation in framboidal and euhedral pyrites in shales.

    PubMed

    Matamoros-Veloza, Adriana; Peacock, Caroline L; Benning, Liane G

    2014-08-19

    The release of Se from shales is poorly understood because its occurrence, distribution, and speciation in the various components of shale are unknown. To address this gap we combined bulk characterization, sequential extractions, and spatially resolved μ-focus spectroscopic analyses and investigated the occurrence and distribution of Se and other associated elements (Fe, As, Cr, Ni, and Zn) and determined the Se speciation at the μ-scale in typical, low bulk Se containing shales. Our results revealed Se primarily correlated with the pyrite fraction with exact Se speciation highly dependent on pyrite morphology. In euhedral pyrites, we found Se(-II) substitutes for S in the mineral structure. However, we also demonstrate that Se is associated with framboidal pyrite grains as a discrete, independent FeSex phase. The presence of this FeSex species has major implications for Se release, because FeSex species oxidize much faster than Se substituted in the euhedral pyrite lattice. Thus, such an FeSex species will enhance and control the dynamics of Se weathering and release into the aqueous environment.

  20. Potential Flow Analysis of Dynamic Ground Effect

    NASA Technical Reports Server (NTRS)

    Feifel, W. M.

    1999-01-01

    Interpretation of some flight test data suggests the presence of a 'dynamic ground effect'. The lift of an aircraft approaching the ground depends on the rate of descent and is lower than the aircraft steady state lift at a same height above the ground. Such a lift deficiency under dynamic conditions could have a serious impact on the overall aircraft layout. For example, the increased pitch angle needed to compensate for the temporary loss in lift would reduce the tail strike margin or require an increase in landing gear length. Under HSR2 an effort is under way to clarify the dynamic ground effect issue using a multi-pronged approach. A dynamic ground effect test has been run in the NASA Langley 14x22 ft wind tunnel. Northup-Grumman is conducting time accurate CFD (Computational Fluid Dynamics) Euler analyses on the National Aerodynamic Simulator facility. Boeing has been using linear potential flow methodology which are thought to provide much needed insight in, physics of this very complex problem. The present report summarizes the results of these potential flow studies.

  1. Aeroservoelastic and Flight Dynamics Analysis Using Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Arena, Andrew S., Jr.

    1999-01-01

    This document in large part is based on the Masters Thesis of Cole Stephens. The document encompasses a variety of technical and practical issues involved when using the STARS codes for Aeroservoelastic analysis of vehicles. The document covers in great detail a number of technical issues and step-by-step details involved in the simulation of a system where aerodynamics, structures and controls are tightly coupled. Comparisons are made to a benchmark experimental program conducted at NASA Langley. One of the significant advantages of the methodology detailed is that as a result of the technique used to accelerate the CFD-based simulation, a systems model is produced which is very useful for developing the control law strategy, and subsequent high-speed simulations.

  2. Nonlinear dynamic analysis for elastic robotic arms

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Rahimi, H. N.

    2011-06-01

    The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and joints. The main contribution of the paper is the comparative assessment of assumed modes and finite element methods as more convenient approaches for computing the nonlinear dynamic of robotic systems. Numerical simulations comprising both methods are carried out and results are discussed. Hence, advantages and disadvantages of each method are illustrated. Then, adding the joint flexibility to the system is dealt with and the obtained model is demonstrated. Finally, a brief description of the optimal motion generation is presented and the simulation is carried out to investigate the role of robot dynamic modeling in the control of robots.

  3. TERPRED: A Dynamic Structural Data Analysis Tool

    PubMed Central

    Walker, Karl; Cramer, Carole L.; Jennings, Steven F.; Huang, Xiuzhen

    2012-01-01

    Computational protein structure prediction mainly involves the main-chain prediction and the side-chain confirmation determination. In this research, we developed a new structural bioinformatics tool, TERPRED for generating dynamic protein side-chain rotamer libraries. Compared with current various rotamer sampling methods, our work is unique in that it provides a method to generate a rotamer library dynamically based on small sequence fragments of a target protein. The Rotamer Generator provides a means for existing side-chain sampling methods using static pre-existing rotamer libraries, to sample from dynamic target-dependent libraries. Also, existing side-chain packing algorithms that require large rotamer libraries for optimal performance, could possibly utilize smaller, target-relevant libraries for improved speed. PMID:25302339

  4. Overview af MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2004-01-01

    This paper presents viewgraphs on NASA Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group Activities. The topics include: 1) Status of programs at MSFC; 2) Fluid Mechanics at MSFC; 3) Relevant Fluid Dynamics Activities at MSFC; and 4) Shuttle Return to Flight.

  5. Speciation Progress: A Case Study on the Bushcricket Poecilimon veluchianus

    PubMed Central

    Eweleit, Lucienne; Reinhold, Klaus; Sauer, Jan

    2015-01-01

    Different mechanisms such as selection or genetic drift permitted e.g. by geographical isolation can lead to differentiation of populations and could cause subsequent speciation. The two subspecies of Poecilimon veluchianus, a bushcricket endemic to central Greece, show a parapatric distribution and are partially reproductively isolated. Therefore, P. veluchianus is suitable to investigate an ongoing speciation process. We based our analysis on sequences of the internal transcribed spacer (ITS) and the mitochondrial control region (CR). The population genetic analysis based on the nuclear marker ITS revealed a barrier to gene flow within the range of Poecilimon veluchianus, which corresponds well to the described subspecies. In contrast to the results based on the nuclear ITS marker, the mitochondrial CR marker does not clearly support the separation into two subspecies with restricted gene flow and a clear contact zone. Furthermore, we could identify isolation by distance (IBD) as one important mechanism responsible for the observed genetic structure (based on the ITS marker). The population genetic analysis based on the nuclear marker ITS also suggests the existence of hybrids in the wild. Furthermore, the simultaneous lack of strong prezygotic barriers and the presence of postzygotic mating barriers, observed in previous laboratory experiments, suggest that a secondary contact after an allopatric phase is more likely than parapatric speciation. PMID:26436732

  6. DynamicBC: A MATLAB Toolbox for Dynamic Brain Connectome Analysis

    PubMed Central

    Xu, Qiang; Ji, Gong-Jun; Zhang, Zhiqiang; Zang, Yu-Feng; Lu, Guangming

    2014-01-01

    Abstract The brain connectome collects the complex network architectures, looking at both static and dynamic functional connectivity. The former normally requires stationary signals and connections. However, the human brain activity and connections are most likely time dependent and dynamic, and related to ongoing rhythmic activity. We developed an open-source MATLAB toolbox DynamicBC with user-friendly graphical user interfaces, implementing both dynamic functional and effective connectivity for tracking brain dynamics from functional MRI. We provided two strategies for dynamic analysis: (1) the commonly utilized sliding-window analysis and (2) the flexible least squares based time-varying parameter regression strategy. The toolbox also implements multiple functional measures including seed-to-voxel analysis, region of interest (ROI)-to-ROI analysis, and voxel-to-voxel analysis. We describe the principles of the implemented algorithms, and then present representative results from simulations and empirical data applications. We believe that this toolbox will help neuroscientists and neurologists to easily map dynamic brain connectomics. PMID:25083734

  7. Dynamical scaling analysis of plant callus growth

    NASA Astrophysics Data System (ADS)

    Galeano, J.; Buceta, J.; Juarez, K.; Pumariño, B.; de la Torre, J.; Iriondo, J. M.

    2003-07-01

    We present experimental results for the dynamical scaling properties of the development of plant calli. We have assayed two different species of plant calli, Brassica oleracea and Brassica rapa, under different growth conditions, and show that their dynamical scalings share a universality class. From a theoretical point of view, we introduce a scaling hypothesis for systems whose size evolves in time. We expect our work to be relevant for the understanding and characterization of other systems that undergo growth due to cell division and differentiation, such as, for example, tumor development.

  8. Dynamic analysis of noncontacting face seals

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1980-01-01

    The dynamic behavior of a noncontacting coned face seal is analyzed taking into account various design parameters and operating conditions. The primary seal ring motion is expressed by a set of nonlinear equations for three degrees of freedom. These equations, which are solved numerically, allow identification of two dimensionless groups of parameters that affect the seal dynamic behavior. Stability maps for various seals are presented. These maps contain a stable-to-unstable transition region in which the ring wobbles at half the shaft frequency. The effect of various parameters on seal stability is discussed and an empirical expression for critical stability is offered.

  9. US EPA's SPECIATE 4.4 Database: Development and Uses

    EPA Science Inventory

    SPECIATE is the U.S. Environmental Protection Agency’s (EPA) repository of volatile organic gas and particulate matter (PM) speciation profiles of air pollution sources. EPA released SPECIATE 4.4 in early 2014 and, in total, the SPECIATE 4.4 database includes 5,728 PM, volatile o...

  10. Environmental harshness, latitude and incipient speciation.

    PubMed

    Weir, Jason T

    2014-02-01

    Are rates of evolution and speciation fastest where diversity is greatest - the tropics? A commonly accepted theory links the latitudinal diversity gradient to a speciation pump model whereby the tropics produce species at a faster rate than extra-tropical regions. In this issue of Molecular Ecology, Botero et al. () test the speciation pump model using subspecies richness patterns for more than 9000 species of birds and mammals as a proxy for incipient speciation opportunity. Rather than using latitudinal centroids, the authors investigate the role of various environmental correlates of latitude as drivers of subspecies richness. Their key finding points to environmental harshness as a positive predictor of subspecies richness. The authors link high subspecies richness in environmental harsh areas to increased opportunities for geographic range fragmentation and/or faster rates of trait evolution as drivers of incipient speciation. Because environmental harshness generally increases with latitude, these results suggest that opportunity for incipient speciation is lowest where species richness is highest. The authors interpret this finding as incompatible with the view of the tropics as a cradle of diversity. Their results are consistent with a growing body of evidence that reproductive isolation and speciation occur fastest at high latitudes.

  11. Sexual conflict promotes speciation in insects

    PubMed Central

    Arnqvist, Göran; Edvardsson, Martin; Friberg, Urban; Nilsson, Tina

    2000-01-01

    Speciation rates among extant lineages of organisms vary extensively, but our understanding of the causes of this variation and, therefore, the processes of speciation is still remarkably incomplete. Both theoretical and empirical studies have indicated that sexual selection is important in speciation, but earlier discussions have focused almost exclusively on the potential role of female mate choice. Recent findings of postmating reproductive conflicts of interest between the sexes suggest a quite different route to speciation. Such conflicts may lead to perpetual antagonistic coevolution between males and females and may thus generate rapid evolutionary divergence of traits involved in reproduction. Here, we assess this hypothesis by contrasting pairs of related groups of insect species differing in the opportunity for postmating sexual conflict. Groups where females mate with many males exhibited speciation rates four times as high as in related groups where females mate only once. Our results not only highlight the general importance of postmating sexual selection in speciation, but also support the recent suggestion that sexual conflict is a key engine of speciation. PMID:10984538

  12. A Dynamic Analysis of Piezoelectric Strained Elements.

    DTIC Science & Technology

    1992-12-01

    of Piezoelectricity , Oxford Univ.Press, Oxford (1990). E38] T.C.Ting, "Dynamic response of composites", Appl. Mechs.Rev., vol. 33, no.12, Dp.1629-16...Plenum Press, New York (1969). 276 [36] J.Zelenka, Piezoelectric Resonators and their Applications, Elsevier, Amsterdam (1986). [37] T.Ikeda, Fundamentals

  13. NPV Sensitivity Analysis: A Dynamic Excel Approach

    ERIC Educational Resources Information Center

    Mangiero, George A.; Kraten, Michael

    2017-01-01

    Financial analysts generally create static formulas for the computation of NPV. When they do so, however, it is not readily apparent how sensitive the value of NPV is to changes in multiple interdependent and interrelated variables. It is the aim of this paper to analyze this variability by employing a dynamic, visually graphic presentation using…

  14. Speciation analysis of selected metals and determination of their total contents in paired serum and cerebrospinal fluid samples: An approach to investigate the permeability of the human blood-cerebrospinal fluid-barrier.

    PubMed

    Nischwitz, Volker; Berthele, Achim; Michalke, Bernhard

    2008-10-10

    Neurodegenerative diseases like Alzheimer's disease and Parkinson's disease are gaining increasing relevance in our aging society. However, the complex multifactorial mechanisms of these diseases are not sufficiently understood yet. Several studies indicate that metal ions play an important role in the promotion of these diseases. Consequently, the transport pathways of metals and their species to the brain are of special interest. Following oral or inhalative uptake metals are absorbed and distributed via the blood stream in the body. Transport into the brain requires crossing of the neural barriers. Our study focuses on the investigation of the permeability of the blood-cerebrospinal fluid (CSF)-barrier for selected metals (Mn, Fe, Cu, Zn, Mg and Ca). For the first time paired human serum and CSF samples obtained from a neurological department were characterised for total metal concentrations and metal species. For CSF few data are available in the literature on total metal contents and applications of element speciation analysis in CSF samples are rare. In our study mean CSF/serum ratios (n=29) were 0.7 for Mn, 0.02 for Fe, 0.02 for Cu, 0.03 for Zn, 1.3 for Mg and 0.5 for Ca. Size exclusion chromatography (SEC) online with inductively coupled plasma mass spectrometry was further developed for the size characterisation of the metal species in CSF and serum with limits of detection of 0.4microgL(-1) for Fe, 0.01microgL(-1) for Mn, 0.2microgL(-1) for Cu, 0.2microgL(-1) for Zn, 0.6microgL(-1) for Mg and 3.8microgL(-1) for Ca in the eluate from the HPLC column. Apart from Mn the application of this technique has not been published for metal speciation in CSF, yet. In the case of some Mn species it turned out that methanol, which was contained in the mobile phase of a SEC method previously published from our group on qualitative characterisation of Mn species, was interfering with the quantification. The modified method developed in this work (with NaCl but without

  15. Integrating atomistic molecular dynamics simulations, experiments, and network analysis to study protein dynamics: strength in unity

    PubMed Central

    Papaleo, Elena

    2015-01-01

    In the last years, we have been observing remarkable improvements in the field of protein dynamics. Indeed, we can now study protein dynamics in atomistic details over several timescales with a rich portfolio of experimental and computational techniques. On one side, this provides us with the possibility to validate simulation methods and physical models against a broad range of experimental observables. On the other side, it also allows a complementary and comprehensive view on protein structure and dynamics. What is needed now is a better understanding of the link between the dynamic properties that we observe and the functional properties of these important cellular machines. To make progresses in this direction, we need to improve the physical models used to describe proteins and solvent in molecular dynamics, as well as to strengthen the integration of experiments and simulations to overcome their own limitations. Moreover, now that we have the means to study protein dynamics in great details, we need new tools to understand the information embedded in the protein ensembles and in their dynamic signature. With this aim in mind, we should enrich the current tools for analysis of biomolecular simulations with attention to the effects that can be propagated over long distances and are often associated to important biological functions. In this context, approaches inspired by network analysis can make an important contribution to the analysis of molecular dynamics simulations. PMID:26075210

  16. Integrating atomistic molecular dynamics simulations, experiments, and network analysis to study protein dynamics: strength in unity.

    PubMed

    Papaleo, Elena

    2015-01-01

    In the last years, we have been observing remarkable improvements in the field of protein dynamics. Indeed, we can now study protein dynamics in atomistic details over several timescales with a rich portfolio of experimental and computational techniques. On one side, this provides us with the possibility to validate simulation methods and physical models against a broad range of experimental observables. On the other side, it also allows a complementary and comprehensive view on protein structure and dynamics. What is needed now is a better understanding of the link between the dynamic properties that we observe and the functional properties of these important cellular machines. To make progresses in this direction, we need to improve the physical models used to describe proteins and solvent in molecular dynamics, as well as to strengthen the integration of experiments and simulations to overcome their own limitations. Moreover, now that we have the means to study protein dynamics in great details, we need new tools to understand the information embedded in the protein ensembles and in their dynamic signature. With this aim in mind, we should enrich the current tools for analysis of biomolecular simulations with attention to the effects that can be propagated over long distances and are often associated to important biological functions. In this context, approaches inspired by network analysis can make an important contribution to the analysis of molecular dynamics simulations.

  17. Dynamic Analysis of Capture Devices for Momentum Exchange with Tethers

    NASA Technical Reports Server (NTRS)

    Canfield, Stephen

    2002-01-01

    One of the significant challenges in developing a momentum exchange / electrodynamic reboost tether system is in the analysis and design of the capture device and its effects on the overall dynamics of the system. The goal of this work is to develop appropriate tether momentum exchange models that can simulate and evaluate the requirements of such a system, and be used to create specifications on the design of a capture device. This report briefly describes dynamic model development, simulation of the momentum exchange process, evaluation of dynamic effects of errors in the momentum exchange process, and the development of guidelines in selecting dynamic properties in the design of a capture device.

  18. Theoretical and software considerations for nonlinear dynamic analysis

    NASA Technical Reports Server (NTRS)

    Schmidt, R. J.; Dodds, R. H., Jr.

    1983-01-01

    In the finite element method for structural analysis, it is generally necessary to discretize the structural model into a very large number of elements to accurately evaluate displacements, strains, and stresses. As the complexity of the model increases, the number of degrees of freedom can easily exceed the capacity of present-day software system. Improvements of structural analysis software including more efficient use of existing hardware and improved structural modeling techniques are discussed. One modeling technique that is used successfully in static linear and nonlinear analysis is multilevel substructuring. This research extends the use of multilevel substructure modeling to include dynamic analysis and defines the requirements for a general purpose software system capable of efficient nonlinear dynamic analysis. The multilevel substructuring technique is presented, the analytical formulations and computational procedures for dynamic analysis and nonlinear mechanics are reviewed, and an approach to the design and implementation of a general purpose structural software system is presented.

  19. Interpolating dynamical systems: Applications to experimental data analysis

    SciTech Connect

    Ecke, R.E.

    1991-01-01

    Experimental data from Rayleigh-Benard convection is used to demonstrate new techniques in data analysis. The data, in the form of Poincare sections, are fit to a map of the plane as a function of a system control parameter. This provides a very useful method for interpolating experimental low-dimensional dynamical systems. The fitted map can then be studied using numerical bifurcation methods or other nonlinear dynamics analysis techniques. 16 refs., 3 figs., 1 tab.

  20. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2002-01-01

    This viewgraph report presents an overview of activities and accomplishments of NASA's Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group. Expertise in this group focuses on high-fidelity fluids design and analysis with application to space shuttle propulsion and next generation launch technologies. Topics covered include: computational fluid dynamics research and goals, turbomachinery research and activities, nozzle research and activities, combustion devices, engine systems, MDA development and CFD process improvements.

  1. Elementary Applications of a Rotorcraft Dynamic Stability Analysis

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1976-01-01

    A number of applications of a rotorcraft aeroelastic analysis are presented to verify that the analysis encompasses the classical solutions of rotor dynamics, and to examine the influence of certain features of the model. Results are given for the following topics: flapping frequency response to pitch control; forward flight flapping stability; pitch/flap flutter and divergence; ground resonance instability; and the flight dynamics of several representative helicopters.

  2. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Wang, Tee-See; Griffin, Lisa; Turner, James E. (Technical Monitor)

    2001-01-01

    This document is a presentation graphic which reviews the activities of the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center (i.e., Code TD64). The work of this group focused on supporting the space transportation programs. The work of the group is in Computational Fluid Dynamic tool development. This development is driven by hardware design needs. The major applications for the design and analysis tools are: turbines, pumps, propulsion-to-airframe integration, and combustion devices.

  3. Lead and cadmium speciation in smelter-contaminated soil

    SciTech Connect

    Bergers, M.; Harris, T.

    1995-12-01

    The design of a {open_quotes}washing{close_quotes} process for the removal and recovery of heavy metals from contaminated soil requires in-depth knowledge of the speciation of the metals. In addition to being present in their original forms (e.g. oxides particulates emitted by a smelter), the contaminating metals may come to be associated with a variety of solid phases commonly present in soil. The {open_quotes}standard{close_quotes} speciation analysis, a series of sequential chemical extractions, has been examined critically, and several improvements to the procedure have been examined. Also, the procedure has been used to characterize samples collected in the vicinity of a zinc smelter that has been in operation for nearly 80 years.

  4. Speciation gradients and the distribution of biodiversity.

    PubMed

    Schluter, Dolph; Pennell, Matthew W

    2017-05-31

    Global patterns of biodiversity are influenced by spatial and environmental variations in the rate at which new species form. We relate variations in speciation rates to six key patterns of biodiversity worldwide, including the species-area relationship, latitudinal gradients in species and genetic diversity, and between-habitat differences in species richness. Although they sometimes mirror biodiversity patterns, recent rates of speciation, at the tip of the tree of life, are often highest where species richness is low. Speciation gradients therefore shape, but are also shaped by, biodiversity gradients and are often more useful for predicting future patterns of biodiversity than for interpreting the past.

  5. Speciation as a sieve for ancestral polymorphism.

    PubMed

    Guerrero, Rafael F; Hahn, Matthew W

    2017-08-09

    Because they are considered rare, balanced polymorphisms are often discounted as crucial constituents of genome-wide variation in sequence diversity. Despite its perceived rarity, however, long-term balancing selection can elevate genetic diversity and significantly affect observed divergence between species. Here, we discuss how ancestral balanced polymorphisms can be "sieved" by the speciation process, which sorts them unequally across descendant lineages. After speciation, ancestral balancing selection is revealed by genomic regions of high divergence between species. This signature, which resembles that of other evolutionary processes, can potentially confound genomic studies of population divergence and inferences of "islands of speciation." © 2017 John Wiley & Sons Ltd.

  6. Using Dynamic Sensitivity Analysis to Assess Testability

    NASA Technical Reports Server (NTRS)

    Voas, Jeffrey; Morell, Larry; Miller, Keith

    1990-01-01

    This paper discusses sensitivity analysis and its relationship to random black box testing. Sensitivity analysis estimates the impact that a programming fault at a particular location would have on the program's input/output behavior. Locations that are relatively \\"insensitive" to faults can render random black box testing unlikely to uncover programming faults. Therefore, sensitivity analysis gives new insight when interpreting random black box testing results. Although sensitivity analysis is computationally intensive, it requires no oracle and no human intervention.

  7. Speciation analysis of calcium, iron, and zinc in casein phosphopeptide fractions from toddler milk-based formula by anion exchange and reversed-phase high-performance liquid chromatography-mass spectrometry/flame atomic-absorption spectroscopy.

    PubMed

    Miquel, Esther; Alegría, Amparo; Barberá, Reyes; Farré, Rosaura

    2005-03-01

    Casein phosphopeptides (CPP) are phosphorylated casein-derived peptides that can be released by in-vitro or in-vivo enzymatic hydrolysis of alpha(s1)-casein, alpha(s2)-casein, and beta-casein (CN). Many of these peptides contain a highly polar acidic sequence of three phosphoseryl groups followed by two glutamic acid residues. These domains are binding sites for minerals such as calcium, iron, and zinc and play an important role in mineral bioavailability. The aim of this study was speciation analysis of calcium, iron, and zinc in CPP fractions from the soluble fraction of a toddler milk-based formula. Methods for CPP separation by anion-exchange high-performance liquid chromatography (AE-HPLC) were combined with CPP identification by reversed-phase high performance liquid chromatography-electrospray ionization mass spectrometry and determination of the calcium, iron, zinc, and phosphorus content of the fractions obtained by AE-HPLC. Calcium and phosphorus were detected in all the analyzed AE-HPLC fractions. Calcium and zinc could be bound to CPP derived from alpha(s1)-CN and alpha(s2)-CN in fraction 3. Iron could be bound to CPP in fraction 4 in which beta-CN(15-34)4P was present with the cluster sequence S(P)S(P)S(P)EE. The results obtained prove the different distribution of calcium, iron, and zinc in heterogeneous CPP fractions.

  8. Selective and sensitive speciation analysis of Cr(VI) and Cr(III) in water samples by fiber optic-linear array detection spectrophotometry after ion pair based-surfactant assisted dispersive liquid-liquid microextraction.

    PubMed

    Yousefi, Seyedeh Mahboobeh; Shemirani, Farzaneh

    2013-06-15

    A simple ion pair based-surfactant assisted dispersive liquid-liquid microextraction (IP-SA-DLLME) was evaluated for extraction and preconcentration of Cr(VI) and Cr(III) in aqueous samples. In this method, which was used for the first time for chromium speciation analysis, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent. Cr(VI) ions were converted into their cationic complex with 1,5-diphenylcarbazide (DPC) and then extracted into 1-octanol dispersed in aqueous solution. Cr(III) ion also can be determined by this procedure after oxidation to Cr(VI). After extraction and phase separation, upper organic phase was transferred to a micro cell of a fiber optic-linear array detection spectrophotometry (FO-LADS). The effects of various parameters on the extraction recovery were investigated. Under the optimized conditions and preconcentration of 10 mL of sample, the enrichment factor of 159 and the detection limit of 0.05 μgL(-1) were obtained. Validation of the method was performed by spiking-recovery method and comparison of results with those obtained by ET-AAS method.

  9. Speciation analysis of triethyl-lead and tributyl-tin compounds in human urine by liquid-liquid extraction and gas chromatography microwave-induced plasma atomic emission detection.

    PubMed

    Zachariadis, George A; Rosenberg, Erwin

    2012-05-01

    This work describes the development of a fast method for speciation analysis of triethyl-lead and tributyl-tin species in urine samples after in situ derivatization by tetraethyl- or tetrapropyl-borate reagents. The alkylation reaction is done in the aqueous and urine medium and the less-polar derivatives are extracted in hexane by liquid-liquid extraction. The species were extracted and the extract was efficiently collected from the aqueous phase after centrifugation. Finally, the organometallic species are separated by gas chromatography and determined from the emission signals of elemental lead and tin. Atomic lead and tin are formed from the organolead and organotin compounds during atomization of the column eluate in a microwave-induced helium plasma source. The simultaneous measurement of lead (Pb) at 405.780 nm and tin (Sn) at 303.419 nm was achieved by an atomic emission detector. Finally, the analytes were determined with satisfactory precision (<5%) and detection limits of 0.05 μg Pb/L and 0.48 μg Sn/L, respectively, when 10 mL of urine is extracted with 1 mL of hexane and 1 μL of extract is injected.

  10. Single Molecule Cluster Analysis dissects splicing pathway conformational dynamics.

    PubMed

    Blanco, Mario R; Martin, Joshua S; Kahlscheuer, Matthew L; Krishnan, Ramya; Abelson, John; Laederach, Alain; Walter, Nils G

    2015-11-01

    We report Single Molecule Cluster Analysis (SiMCAn), which utilizes hierarchical clustering of hidden Markov modeling-fitted single-molecule fluorescence resonance energy transfer (smFRET) trajectories to dissect the complex conformational dynamics of biomolecular machines. We used this method to study the conformational dynamics of a precursor mRNA during the splicing cycle as carried out by the spliceosome. By clustering common dynamic behaviors derived from selectively blocked splicing reactions, SiMCAn was able to identify the signature conformations and dynamic behaviors of multiple ATP-dependent intermediates. In addition, it identified an open conformation adopted late in splicing by a 3' splice-site mutant, invoking a mechanism for substrate proofreading. SiMCAn enables rapid interpretation of complex single-molecule behaviors and should prove useful for the comprehensive analysis of a plethora of dynamic cellular machines.

  11. Dynamics analysis of space robot manipulator with joint clearance

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Bai, Zheng Feng

    2011-04-01

    A computational methodology for analysis of space robot manipulator systems, considering the effects of the clearances in the joint, is presented. The contact dynamics model in joint clearance is established using the nonlinear equivalent spring-damp model and the friction effect is considered using the Coulomb friction model. The space robot system dynamic equation of manipulator with clearance is established. Then the dynamics simulation is presented and the dynamics characteristics of robot manipulator with clearance are analyzed. This work provides a practical method to analyze the dynamics characteristics of space robot manipulator with joint clearance and improves the engineering application. The computational methodology can predict the effects of clearance on space robot manipulator preferably, which is the basis of space robot manipulator design, precision analysis and ground test.

  12. Structural dynamic analysis of the Space Shuttle Main Engine

    NASA Technical Reports Server (NTRS)

    Scott, L. P.; Jamison, G. T.; Mccutcheon, W. A.; Price, J. M.

    1981-01-01

    This structural dynamic analysis supports development of the SSME by evaluating components subjected to critical dynamic loads, identifying significant parameters, and evaluating solution methods. Engine operating parameters at both rated and full power levels are considered. Detailed structural dynamic analyses of operationally critical and life limited components support the assessment of engine design modifications and environmental changes. Engine system test results are utilized to verify analytic model simulations. The SSME main chamber injector assembly is an assembly of 600 injector elements which are called LOX posts. The overall LOX post analysis procedure is shown.

  13. Dynamic mechanical analysis: A practical introduction to techniques and applications

    SciTech Connect

    Menard, K.

    1999-03-01

    This introduction provides the chemist, chemical engineer, or materials scientists with a starting point to understand the applications of dynamic mechanical analysis, its workings, and its advantages and limitations. This book serves as a systematic study of manufacturing polymeric materials and components as well as for developing new materials. Contents include: introduction to dynamic mechanical analysis; basic rheological concepts: stress, strain, and flow; rheology basic: creep-recovery and stress relaxation; dynamic testing; time-temperature scans part 1: transitions in polymers; time and temperature studies part 2: thermosets; frequency scans; DMA applications to real problems: guidelines; and appendix: sample experiments for the DMA.

  14. Three-dimensional dynamic response analysis of earth dams

    SciTech Connect

    Mejia, L.H.

    1981-01-01

    The purpose of the present work has been to develop numerical techniques for the three-dimensional dynamic analysis of earth and rockfill dams and to study the dynamic behavior of embankment dams in three dimensions. A computer program suitable for the three-dimensional dynamic response analysis of earth dams was used to back-calculate the dynamic material properties of Oroville Dam from the recorded response of the dam to the August 1, 1975 Oroville earthquake. The dynamic response characteristics of earth dams which exhibit considerable three-dimensional behavior have been studied and the applicability of two-dimensional analysis to the computation of the dynamic response of such structures has been evaluated. Additionally, the effects that the degree of discretization in the cross-valley direction has on the computed three-dimensional dynamic response of earth dams have been studied. A K/sub 2/max value of 170 was found to be representative of the in-situ dynamic characteristics of the Oroville gravels. The three-dimensional effects of canyon geometry on the dynamic response of dams in triangular canyons were found to depend on the crest length to height ratio, L/H, of the dam. For dams with L/H greater than 7, these effects are small. The dynamic characteristics of these dams can, therefore, be simulated reasonably well using two-dimensional analyses. However, 2-D analyses cannot simulate correctly the dynamic response of dams in narrower canyons since the effects of canyon geometry for these dams are very pronounced.

  15. A Wigner Distribution Analysis of Scattering Dynamics

    NASA Astrophysics Data System (ADS)

    Weeks, David; Lacy, Brent

    2009-04-01

    Using the time dependent Channel Packet Method (CPM),ootnotetextD.E.Weeks, T.A.Niday, S.H.Yang, J Chem Phys. 125, 164301 (2006). a Fourier transformation of the correlation function between evolving wave packets is used to compute scattering matrix elements. The correlation function can also be used to compute a Wigner distribution as a function of time and energy. This scattering Wigner distribution is then used to investigate times at which various energetic contributions to the scattering matrix are made during a molecular collision. We compute scattering Wigner distributions for a variety of molecular systems and use them to characterize the associated molecular dynamics. In particular, the square well provides a simple and easily modified potential to study the relationship between the scattering Wigner distribution and wave packet dynamics. Additional systems that are being studied include the collinear H + H2 molecular reaction, and the non-adiabatic B + H2 molecular collision.

  16. Dynamic network analysis of protein interactions

    NASA Astrophysics Data System (ADS)

    Almaas, Eivind; Deri, Joya

    2007-03-01

    Network approaches have recently become a popular tool to study complex systems such as cellular metabolism and protein interactions. A substantial number of analyses of the protein interaction network (PIN) of the yeast Saccharomyces cerevisiae have considered this network as a static entity, not taking the network's dynamic nature into account. Here, we examine the time-variation of gene regulation superimposed on the PIN by defining mRNA expression profiles throughout the cell cycle as node weights. To characterize these network dynamics, we have both developed a set of novel network measures as well as studied previously published measures for weighted networks. We expect that our approach will provide a deeper understanding of protein regulation during the cell cycle.

  17. Dynamic data analysis in obstructive sleep apnea.

    PubMed

    Karunajeewa, Asela S; Abeyratne, Udantha R; Rathnayake, Suren I; Swarnkar, V

    2006-01-01

    Obstructive Sleep Apnea (OSA) is a serious disease caused by the collapse of upper airways during sleep. The present method of measuring the severity of OSA is the Apnea Hypopnea Index (AHI). The AHI is defined as the average number of Obstructive events (Apnea and Hypopnea, OAH-events) during the total sleep period. The number of occurrence of OAH events during each hour of sleep is a random variable with an unknown probability density function. Thus the measure AHI alone is insufficient to describe its true nature. We propose a new measure Dynamic Apnea Hypopnea Index Time Series (DAHI), which captures the temporal density of Apnea event over shorter time intervals, and use its higher moments to obtain a dynamic characterization of OSA.

  18. Fluid Dynamic Analysis of Volcanic Tremor,

    DTIC Science & Technology

    1982-10-01

    analytical potential of the fluid dynamic theory, we consider a single-phase fluid, a melt of Mount Hood andesite at 1250C, in which significant pressure...existing steady condition. A likely Volcanic earthquakes are known to occur at ba- mechanism, important during pre-eruptive periods, saltic, andesitic and...melts can be large. of Mount Hood andesite composed of 60% SiO2 . A numerical solution of the free vibrational eigen- The melt was totally fluid at

  19. Incremental Centrality Algorithms for Dynamic Network Analysis

    DTIC Science & Technology

    2013-08-01

    dynamically. Betweenness is also commonly discussed within the concept of vulnerability of networks to different attacks since it is useful for...perform coordinated attacks . In other words, we issue shrinking network updates and introduce progressive failures to the central nodes. Simulated...protocol ( OLSR ) as the routing protocol. It is a proactive link state routing protocol where each node stores next-hop destinations for all nodes in

  20. Influence Diagrams: Automated Analysis with Dynamic Programming

    DTIC Science & Technology

    1988-12-01

    demonstrating both the efficiency of the dynamic programming features and the limitations of influence diagrams in modeling problems with significant...Introduction 1.1 General Background Influence diagrams are a -eccntly developed graphical modeling tool for repre- senting both the conceptual elements and the...the model [9:10]. The types of node included in basic influence diagrams are (see Figure 1): Chance Node The chance node represents a random variable

  1. Network analysis of human heartbeat dynamics

    NASA Astrophysics Data System (ADS)

    Shao, Zhi-Gang

    2010-02-01

    We construct the complex networks of human heartbeat dynamics and investigate their statistical properties, using the visibility algorithm proposed by Lacasa and co-workers [Proc. Natl. Acad. Sci. U.S.A. 105, 4972 (2008)]. Our results show that the associated networks for the time series of heartbeat interval are always scale-free, high clustering, hierarchy, and assortative mixing. In particular, the assortative coefficient of associated networks could distinguish between healthy subjects and patients with congestive heart failure.

  2. Metal speciation in a complexing soft film layer: a theoretical dielectric relaxation study of coupled chemodynamic and electrodynamic interfacial processes.

    PubMed

    Merlin, Jenny; Duval, Jérôme F L

    2012-04-07

    We report a comprehensive formalism for the dynamics of metal speciation across an interphase formed between a complexing soft film layer and an electrolyte solution containing indifferent ions and metal ions that form complexes with charged molecular ligands distributed throughout the film. The analysis integrates the intricate interplay between metal complexation kinetics and diffusive metal transfer from/toward the ligand film, together with the kinetics of metal electrostatic partitioning across the film/solution interphase. This partitioning is determined by the settling dynamics of the interfacial electric double layer (EDL), as governed by time-dependent conduction-diffusion transports of both indifferent and reactive metal ions. The coupling between such chemodynamic and electrodynamic processes is evaluated via derivation of the dielectric permittivity increment for the ligand film/electrolyte interphase that is perturbed upon application of an ac electric field (pulsation ω) between electrodes supporting the films. The dielectric response is obtained from the ω-dependent distributions of all ions across the ligand film, as ruled by coupled Poisson-Nernst-Planck equations amended for a chemical source term involving the intra-film complex formation and dissociation pulsations (ω(a) and ω(d) respectively). Dielectric spectra are discussed for bare and film coated-electrodes over a wide range of field pulsations and Deborah numbers De = ω(a,d)/ω(diff), where ω(diff) is the electric double layer relaxation pulsation. The frequency-dependent dynamic or inert character of the formed metal complexes is then addressed over a time window that ranges from transient to fully relaxed EDL. The shape and magnitude of the dielectric spectra are further shown to reflect the lability of dynamic complexes, i.e. whether the overall speciation process at a given pulsation ω is primarily rate-limited either by complexation kinetics or by ion-transport dynamics. The

  3. Dynamic analysis of a parasite population model

    NASA Astrophysics Data System (ADS)

    Sibona, G. J.; Condat, C. A.

    2002-03-01

    We study the dynamics of a model that describes the competitive interaction between an invading species (a parasite) and its antibodies in an living being. This model was recently used to examine the dynamical competition between Tripanosoma cruzi and its antibodies during the acute phase of Chagas' disease. Depending on the antibody properties, the model yields three types of outcomes, corresponding, respectively, to healing, chronic disease, and host death. Here, we study the dynamics of the parasite-antibody interaction with the help of simulations, obtaining phase trajectories and phase diagrams for the system. We show that, under certain conditions, the size of the parasite inoculation can be crucial for the infection outcome and that a retardation in the stimulated production of an antibody species may result in the parasite gaining a definitive advantage. We also find a criterion for the relative sizes of the parameters that are required if parasite-generated decoys are indeed to help the invasion. Decoys may also induce a qualitatively different outcome: a limit cycle for the antibody-parasite population phase trajectories.

  4. Possible method for dissolved organic carbon speciation in forest soils

    NASA Astrophysics Data System (ADS)

    Drabek, O.; Tejnecký, V.; Ash, C.; Hubova, P.; Boruvka, L.

    2013-12-01

    Dissolved organic carbon (DOC) is a natural part of dissolved organic matter and it plays an important role in the biogeochemistry of soil processes. Low Molecular Mass Organic Acids (LMMOA) are an essential part of DOC. These acids play a key role in chemical processes that affect the entire soil environment. Knowing the amount of DOC and the speciation of LMMOA is required for realistic equilibrium modelling of soil chemical processes and transport mechanisms. There have been a number of proposed methods for the quantitative analysis of DOC and for speciation of LMMOA. The first aim of this contribution is to introduce and test a modified spectroscopic method for the determination of water-extractable organic carbon (WEOC) from forest soils. In general this method is based on the oxidization of WEOC by chromium-sulphuric acid. The presented method can be used as an economical alternative to the classical, more financially demanding elemental analysis. However, the main aim is to test the reliability of the method for LMMOA speciation. Ion exchange chromatography (IC) with hydroxide elution has proven to be a useful tool for the determination of LMMOA in many different water-based samples. However, the influence of multivalent cations (often present in environmental samples) on IC results has not yet been sufficiently studied. In order to assess the influence of Al, Fe, Mn, Mg and Ca on the amount of LMMOA determined by IC, an extensive set of model solutions was prepared and immediately analysed by means of IC. Moreover, the influence of pH on determined amounts of LMMOA in model solutions and representative soil aqueous extracts was investigated. These experimental results were compared to expected values and also to results provided by the chemical equilibrium model - PHREEQC. Based on the above listed research, some modifications to the common IC method for LMMOA speciation are presented.

  5. Is Speciation Accompanied by Rapid Evolution? Insights from Comparing Reproductive and Nonreproductive Transcriptomes in Drosophila

    PubMed Central

    Jagadeeshan, Santosh; Haerty, Wilfried; Singh, Rama S.

    2011-01-01

    The tempo and mode of evolutionary change during speciation have remained contentious until recently. While much of the evidence claiming speciation is an abrupt and rapid process comes from fossil data, recent molecular phylogenetics show that the background of gradual evolution is often broken by accelerated rates of molecular evolution during speciation. However, what kinds of genes affect or are affected by speciation remains unexplored. Our analysis of 4843 protein-coding genes in five species of the Drosophila melanogaster subgroup shows that while ~70% of genes follow clock-like evolution, between 17–19.67% of loci show signatures of accelerated rates of evolution in recently formed species. These genes show 2-3-fold higher rates of substitution in recently diverged species compared to older species. This fraction of loci affects a diverse range of functions. Only a small proportion of reproductive genes experience speciation-related accelerated changes but many sex-and -reproduction related genes show an interesting pattern of persistent rapid evolution suggesting that sex-and-reproduction related genes are under constant selective pressures. The identification of loci associated with accelerated evolution allows us to address the mechanisms of rapid evolution and speciation, which in our study appears to be a combination of both selection and rapid demographical changes. PMID:21869936

  6. Persistence of within-species lineages: a neglected control of speciation rates.

    PubMed

    Dynesius, Mats; Jansson, Roland

    2014-04-01

    We present a framework distinguishing three principal controls of speciation rate: rate of splitting, level of persistence, and length of speciation duration. We contend that discussions on diversification become clearer in the light of this framework, because speciation rate variation could be attributed to any of these controls. In particular, we claim that the role of persistence of within-species lineages in controlling speciation rates has been greatly underappreciated. More emphasis on the persistence control would change expectations of the role of several biological traits and environmental factors, because they may drive speciation rate in one direction through the persistence control and in the opposite direction through the other two controls. Traits and environments have been little studied regarding their influence on speciation rate through the persistence control, with climatic fluctuations being a relatively well-studied exception. Considering the recent advances in genomic and phylogenetic analysis, we think that the time is ripe for applying the framework in empirical research. Variation among clades and areas (and thus among traits and environments) in the importance of the three rate controls could be addressed for example by dating splitting events, detecting within-species lineages, and scanning genomes for evidence of divergent selection.

  7. VOCs Speciation From Steam Boiler Stacks of Industries Located in Naucalpan

    NASA Astrophysics Data System (ADS)

    Mejia, G. M.; Tejeda, D. D.; Bremauntz, M. P.; Valdez, A.; Montufar, P. C.; Martinez, M. A.; Sierra, M. J.; Gonzalez, C. A.

    2007-05-01

    Results of VOCs speciation from industrial steam boiler stacks located in Naucalpan are presented and discussed. This municipality is located north of the Metropolitan Zone of the Valley of Mexico (MZVM). Speciation of VOCs is important to generate information about sources of pollution, to update emission inventories, to study the dynamics of pollutants in the atmosphere, and to estimate possible risks of population exposure. This information is valuable for decision making on air pollution control strategies. Samples from 35 steam boilers form industries burning Diesel, LPG, or CNG were taken using the US-EPA Method 18. Selected samples from the use of different fuels were analyzed using gas chromatography and flame ionization detection (GC-FID) according to US-EPA protocol TO-14. The VOCs analyzed included alkanes of 9 carbons or less, alkenes of 7 carbons or less and aromatics (families of benzene). The results show consistency on the VOCs detected on Diesel samples. The main compounds found were 1- Butene+iButylene, m/p-Xylene, Ethane, Propene, Propane, Acetylene, 2Me-1Butene, and Toluene. The average concentrations of these compounds were in the range of 130 to 385 ppbC. The results of LPG samples did not show a definite pattern of VOCs, although light components predominate and, in some samples, Toluene and Xylene. These last components were not expected for industries reporting the use of LPG, perhaps due to the use of a combination of fuels and mistakes in the reports of fuel used at the time of sampling. The analysis of CNG samples show predominance of light VOCs, in the range of 90 to 300 ppbC. As in the case of LPG, some aromatics showed high concentrations in some samples analyzed perhaps due to the use of different fuels in the boiler. The results of this study are the first results of VOCs speciation obtained form exhaust gases from stacks of Mexican industries. The data reported are valuable to analyze emission inventories of VOCs and to better

  8. Unsupervised analysis of small animal dynamic Cerenkov luminescence imaging

    NASA Astrophysics Data System (ADS)

    Spinelli, Antonello E.; Boschi, Federico

    2011-12-01

    Clustering analysis (CA) and principal component analysis (PCA) were applied to dynamic Cerenkov luminescence images (dCLI). In order to investigate the performances of the proposed approaches, two distinct dynamic data sets obtained by injecting mice with 32P-ATP and 18F-FDG were acquired using the IVIS 200 optical imager. The k-means clustering algorithm has been applied to dCLI and was implemented using interactive data language 8.1. We show that cluster analysis allows us to obtain good agreement between the clustered and the corresponding emission regions like the bladder, the liver, and the tumor. We also show a good correspondence between the time activity curves of the different regions obtained by using CA and manual region of interest analysis on dCLIT and PCA images. We conclude that CA provides an automatic unsupervised method for the analysis of preclinical dynamic Cerenkov luminescence image data.

  9. Unsupervised analysis of small animal dynamic Cerenkov luminescence imaging

    NASA Astrophysics Data System (ADS)

    Spinelli, Antonello E.; Boschi, Federico

    2011-12-01

    Clustering analysis (CA) and principal component analysis (PCA) were applied to dynamic Cerenkov luminescence images (dCLI). In order to investigate the performances of the proposed approaches, two distinct dynamic data sets obtained by injecting mice with 32P-ATP and 18F-FDG were acquired using the IVIS 200 optical imager. The k-means clustering algorithm has been applied to dCLI and was implemented using interactive data language 8.1. We show that cluster analysis allows us to obtain good agreement between the clustered and the corresponding emission regions like the bladder, the liver, and the tumor. We also show a good correspondence between the time activity curves of the different regions obtained by using CA and manual region of interest analysis on dCLIT and PCA images. We conclude that CA provides an automatic unsupervised method for the analysis of preclinical dynamic Cerenkov luminescence image data.

  10. Assessment of aerodynamic and dynamic models in a comprehensive analysis

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1985-01-01

    The history, status, and lessons of a comprehensive analysis for rotorcraft are reviewed. The development, features, and capabilities of the analysis are summarized, including the aerodynamic and dynamic models that were used. Examples of correlation of the computational results with experimental data are given, extensions of the analysis for research in several topics of helicopter technology are discussed, and the experiences of outside users are summarized. Finally, the required capabilities and approach for the next comprehensive analysis are described.

  11. Diploid versus haploid models of neutral speciation.

    PubMed

    Schneider, David M; Baptestini, Elizabeth M; de Aguiar, Marcus A M

    2016-03-01

    Neutral models of speciation based on isolation by distance and assortative mating, termed topopatric, have shown to be successful in describing abundance distributions and species-area relationships. Previous works have considered this type of process in the context of haploid genomes. Here we discuss the implementation of two schemes of dominance to analyze the effects of diploidy: a complete dominance model in which one allele dominates over the other and a perfect codominant model in which heterozygous genotypes give rise to a third phenotype. In the case of complete dominance, we observe that speciation requires stronger spatial inbreeding in comparison to the haploid model. For perfect codominance, instead, speciation demands stronger genetic assortativeness. Nevertheless, once speciation is established, the three models predict the same abundance distributions even at the quantitative level, revealing the robustness of the original mechanism to describe biodiversity features.

  12. Chromosomes, conflict, and epigenetics: chromosomal speciation revisited.

    PubMed

    Brown, Judith D; O'Neill, Rachel J

    2010-01-01

    Since Darwin first noted that the process of speciation was indeed the "mystery of mysteries," scientists have tried to develop testable models for the development of reproductive incompatibilities-the first step in the formation of a new species. Early theorists proposed that chromosome rearrangements were implicated in the process of reproductive isolation; however, the chromosomal speciation model has recently been questioned. In addition, recent data from hybrid model systems indicates that simple epistatic interactions, the Dobzhansky-Muller incompatibilities, are more complex. In fact, incompatibilities are quite broad, including interactions among heterochromatin, small RNAs, and distinct, epigenetically defined genomic regions such as the centromere. In this review, we will examine both classical and current models of chromosomal speciation and describe the "evolving" theory of genetic conflict, epigenetics, and chromosomal speciation.

  13. CORRELATING METAL SPECIATION IN SOILS TO RISK

    EPA Science Inventory

    Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

  14. CORRELATING METAL SPECIATION IN SOILS TO RISK

    EPA Science Inventory

    Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

  15. Physicochemical speciation of lead in drinking water.

    PubMed

    Harrison, R M; Laxen, D P

    1980-08-21

    Recent studies have highlighted the importance of drinking water as a route of human exposure to lead. Whilst there are ample data on lead concentrations in drinking water, little is known of its physical and chemical forms (physicochemical speciation). Such information is important as the speciation of ingested lead influences the efficiency of absorption from the gastrointestinal tract. Knowledge of speciation should also provide a fuller understanding of the factors controlling the solubility of lead in potable waters and hence assist in devising the most cost-effective means of plumbosolvency control. We have determined experimentally the speciation of lead in three different tapwaters and report here diverse forms of dissolved and particle-associated lead, dependent primarily on the chemical matrix of the raw water.

  16. Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

    NASA Astrophysics Data System (ADS)

    Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

    2014-12-01

    Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

  17. Literal algebra for satellite dynamics. [perturbation analysis

    NASA Technical Reports Server (NTRS)

    Gaposchkin, E. M.

    1975-01-01

    A description of the rather general class of operations available is given and the operations are related to problems in satellite dynamics. The implementation of an algebra processor is discussed. The four main categories of symbol processors are related to list processing, string manipulation, symbol manipulation, and formula manipulation. Fundamental required operations for an algebra processor are considered. It is pointed out that algebra programs have been used for a number of problems in celestial mechanics with great success. The advantage of computer algebra is its accuracy and speed.

  18. Analytical analysis of particle-core dynamics

    SciTech Connect

    Batygin, Yuri K

    2010-01-01

    Particle-core interaction is a well-developed model of halo formation in high-intensity beams. In this paper, we present an analytical solution for averaged, single particle dynamics, around a uniformly charged beam. The problem is analyzed through a sequence of canonical transformations of the Hamiltonian, which describes nonlinear particle oscillations. A closed form expression for maximum particle deviation from the axis is obtained. The results of this study are in good agreement with numerical simulations and with previously obtained data.

  19. Dynamic analysis of grinding using the population balance model

    SciTech Connect

    Williams, M.C. |

    1995-12-31

    The dynamic behavior of batch mill, CSTR mill, and a closed grinding network consisting of a mill, sump, and cyclone was analyzed using the dynamic population balance model (PBM). The dynamic solution of the PBM of a batch, CSTR and a closed grinding network consisting of a mill, sump, and cyclone forms the basis of the dynamic analysis presented here. Two numerical dynamic solution approaches were used. These are: (1) providing additional constraints on breakage selection functions or (2) performing the Arbiter-Bhrany (or other) normalization of the selection functions. Actual experimental anthracite batch grinding data was used to obtain the functionality of the batch dynamic mill selection and breakage functions for a real physical system. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations is used to solve the batch dynamic PBM grinding equations to obtain the grinding selection and breakage rate functions. The mill, sump and hydrocyclone were modeled as a CSTR operating at various retention times. Batch dynamic PBM data was used to provide the mill kinetic and breakage selection function data. Different dynamic solutions were obtained depending on the numerical approach used. Each solution approach to a dynamic PBM with transport, while giving the same prediction for a single batch grinding time, gives different solutions or predictions for mill composition for other grinding times. This fact makes dynamic nodal analysis and control problematic. The fact that the constraint solution approach gives a solution may suggest that normalization for closed networks is not necessary. Differences in solutions to the PBM cannot be excused away by inaccuracies in the data used to model the grinding phenomenon.

  20. Arsenic concentration and speciation in infant formulas and first foods.

    PubMed

    Jackson, Brian P; Taylor, Vivien F; Punshon, Tracy; Cottingham, Kathryn L

    2012-01-01

    Arsenic exposure to humans is pervasive, and, increasingly, studies are revealing adverse health effects at ever lower doses. Drinking water is the main route of exposure for many individuals; however, food can be a significant source of arsenic to an individual, especially if their diet is rice-based. Infants are particularly susceptible to dietary exposure, since many first foods contain rice and they have a low body mass. Here we report on arsenic concentration and speciation in infant formulas and first foods. Speciation is essential for food analysis because of the much greater toxicity of inorganic arsenic species and the possibility that arsenic in food (unlike water) may be present in either inorganic or organic forms. Infant milk formulas were low in total arsenic (2.2-12.6 ng g(-1), n=15). Non-dairy formulas were significantly higher in arsenic than dairy-based formulas. Arsenic in formula was almost exclusively inorganic and predominantly arsenic(V). Arsenic concentration in purees (n=41) and stage 3 foods (n=18) ranged from 0.3-22 ng g(-1). Rice-fortified foods had significantly higher total arsenic concentrations than non rice-based foods. Again arsenic speciation was predominantly inorganic; arsenic(III) was the main species with lower concentrations of DMA and arsenic(V) also present. These data confirm that infants are exposed to arsenic via diet, and suggest that careful attention to diet choices may limit this.

  1. The 'shape' of phylogenies under simple random speciation models

    NASA Astrophysics Data System (ADS)

    Steel, Mike; McKenzie, Andy

    We describe some discrete structural properties of evolutionary trees generated under simple null models of speciation, such as the Yule model. These models have been used as priors in Bayesian approaches to phylogenetic analysis, and also to test hypotheses concerning the speciation process. Here we describe new results for four properties of trees generated under such models. Firstly, for a rooted tree generated by the Yule model we describe the probability distribution on the depth (number of edges from the root) of the most recent common ancestor of a random subset of k species. Secondly, for trees generated under the Yule and uniform models, we describe the induced distribution they generate on the number Cn of cherries in the tree, where a cherry is a pair of leaves each of which is adjacent to a common ancestor. Next we show that, for trees generated under the Yule model, the approximate position of the root can be estimated from the associated unrooted tree, even for trees with a large number of leaves. Finally, we analyse a biologically-motivated extension of the Yule model and describe its distribution on tree shapes when speciation occurs in rapid bursts.

  2. Bootstrap Standard Error Estimates in Dynamic Factor Analysis

    ERIC Educational Resources Information Center

    Zhang, Guangjian; Browne, Michael W.

    2010-01-01

    Dynamic factor analysis summarizes changes in scores on a battery of manifest variables over repeated measurements in terms of a time series in a substantially smaller number of latent factors. Algebraic formulae for standard errors of parameter estimates are more difficult to obtain than in the usual intersubject factor analysis because of the…

  3. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2003-01-01

    TD64, the Applied Fluid Dynamics Analysis Group, is one of several groups with high-fidelity fluids design and analysis expertise in the Space Transportation Directorate at Marshall Space Flight Center (MSFC). TD64 assists personnel working on other programs. The group participates in projects in the following areas: turbomachinery activities, nozzle activities, combustion devices, and the Columbia accident investigation.

  4. Bootstrap Standard Error Estimates in Dynamic Factor Analysis

    ERIC Educational Resources Information Center

    Zhang, Guangjian; Browne, Michael W.

    2010-01-01

    Dynamic factor analysis summarizes changes in scores on a battery of manifest variables over repeated measurements in terms of a time series in a substantially smaller number of latent factors. Algebraic formulae for standard errors of parameter estimates are more difficult to obtain than in the usual intersubject factor analysis because of the…

  5. Automatic A-set selection for dynamics analysis

    NASA Technical Reports Server (NTRS)

    Allen, Tom

    1993-01-01

    A method for selecting optimum NASTRAN analysis set degrees of freedom for the dynamic eigenvalue problem is described. Theoretical development of the Guyan reduction procedure on which the method is based is first summarized. The algorithm used to select the analysis set degrees of freedom is then developed. Two example problems are provided to demonstrate the accuracy of the algorithm.

  6. Conducting Qualitative Data Analysis: Managing Dynamic Tensions within

    ERIC Educational Resources Information Center

    Chenail, Ronald J.

    2012-01-01

    In the third of a series of "how-to" essays on conducting qualitative data analysis, Ron Chenail examines the dynamic tensions within the process of qualitative data analysis that qualitative researchers must manage in order to produce credible and creative results. These tensions include (a) the qualities of the data and the qualitative data…

  7. Refining the conditions for sympatric ecological speciation.

    PubMed

    Débarre, F

    2012-12-01

    Can speciation occur in a single population when different types of resources are available, in the absence of any geographical isolation, or any spatial or temporal variation in selection? The controversial topics of sympatric speciation and ecological speciation have already stimulated many theoretical studies, most of them agreeing on the fact that mechanisms generating disruptive selection, some level of assortment, and enough heterogeneity in the available resources, are critical for sympatric speciation to occur. Few studies, however, have combined the three factors and investigated their interactions. In this article, I analytically derive conditions for sympatric speciation in a general model where the distribution of resources can be uni- or bimodal, and where a parameter controls the range of resources that an individual can exploit. This approach bridges the gap between models of a unimodal continuum of resources and Levene-type models with discrete resources. I then test these conditions against simulation results from a recently published article (Thibert-Plante & Hendry, 2011, J. Evol. Biol. 24: 2186-2196) and confirm that sympatric ecological speciation is favoured when (i) selection is disruptive (i.e. individuals with an intermediate trait are at a local fitness minimum), (ii) resources are differentiated enough and (iii) mating is assortative. I also discuss the role of mating preference functions and the need (or lack thereof) for bimodality in resource distributions for diversification.

  8. The ecological genetics of homoploid hybrid speciation.

    PubMed

    Gross, B L; Rieseberg, L H

    2005-01-01

    Our understanding of homoploid hybrid speciation has advanced substantially since this mechanism of species formation was codified 50 years ago. Early theory and research focused almost exclusively on the importance of chromosomal rearrangements, but it later became evident that natural selection, specifically ecological selection, might play a major role as well. In light of this recent shift, we present an evaluation of ecology's role in homoploid hybrid speciation, with an emphasis on the genetics underlying ecological components of the speciation process. We briefly review new theoretical developments related to the ecology of homoploid hybrid speciation; propose a set of explicit, testable questions that must be answered to verify the role of ecological selection in homoploid hybrid speciation; discuss published work with reference to these questions; and also report new data supporting the importance of ecological selection in the origin of the homoploid hybrid sunflower species Helianthus deserticola. Overall, theory and empirical evidence gathered to date suggest that ecological selection is a major factor promoting homoploid hybrid speciation, with the strongest evidence coming from genetic studies.

  9. The Ecological Genetics of Homoploid Hybrid Speciation

    PubMed Central

    Gross, B. L.; Rieseberg, L. H.

    2008-01-01

    Our understanding of homoploid hybrid speciation has advanced substantially since this mechanism of species formation was codified 50 years ago. Early theory and research focused almost exclusively on the importance of chromosomal rearrangements, but it later became evident that natural selection, specifically ecological selection, might play a major role as well. In light of this recent shift, we present an evaluation of ecology’s role in homoploid hybrid speciation, with an emphasis on the genetics underlying ecological components of the speciation process. We briefly review new theoretical developments related to the ecology of homoploid hybrid speciation; propose a set of explicit, testable questions that must be answered to verify the role of ecological selection in homoploid hybrid speciation; discuss published work with reference to these questions; and also report new data supporting the importance of ecological selection in the origin of the homoploid hybrid sunflower species Helianthus deserticola. Overall, theory and empirical evidence gathered to date suggest that ecological selection is a major factor promoting homoploid hybrid speciation, with the strongest evidence coming from genetic studies. PMID:15618301

  10. Learning dynamics from nonstationary time series: Analysis of electroencephalograms

    NASA Astrophysics Data System (ADS)

    Gribkov, Dmitrii; Gribkova, Valentina

    2000-06-01

    We propose an empirical modeling technique for a nonstationary time series analysis. Proposed methods include a high-dimensional (N>3) dynamical model construction in the form of delay differential equations, a nonparametric method of respective time delay calculation, the detection of quasistationary regions of the process by reccurence analysis in the space of model coefficients, and final fitting of the model to quasistationary segments of observed time series. We also demonstrate the effectiveness of our approach for nonstationary signal classification in the space of model coefficients. Applying the empirical modeling technique to electroencephalogram (EEG) records analysis, we find evidence of high-dimensional nonlinear dynamics in quasistationary EEG segments. Reccurence analysis of model parameters reveals long-term correlations in nonstationary EEG records. Using the dynamical model as a nonlinear filter, we find that different emotional states of subjects can be clearly distinguished in the space of model coefficients.

  11. [Macroeconomic analysis: agro-nutritional dynamics].

    PubMed

    Coussy, J

    1992-01-01

    This reflection on the renewed prominence of macroeconomic analysis in the area of food and agriculture, especially in Africa, assesses the history, limitations, and potential of the discipline as applied in formulation of agricultural policy. It begins by tracing the development and history of macroeconomic analysis from the emergence of liberal political economy in the late 18th century. The evolution of macroeconomic analysis applied to food and agriculture has not been linear; periods of eclipse have alternated with periods of influence. Most recently, in the 1960s, macroeconomic analysis was important in attempts to understand the place of agriculture in national economies, but the misuse of its vocabulary to justify a number of controversial policy actions created lasting distrust. The questions addressed by macroeconomic analysis and the potential contributions of its use in the 1960s are discussed, followed by an analysis of the reasons for renewed attention to the macroeconomic viewpoint beginning with the balance of payments crisis of the 1980s. The recent growth of institutional demand for macroeconomic analysis and policy has been accompanied by misunderstanding and inflated expectations as to its usefulness, while suspicions linger. The pressures encouraging broadened use of macroeconomic analysis are identified, including the growing influence of purely macroeconomic processes such as urbanization, the demographic transition, and the debt crisis; the intensifying of national and international market constraints affecting food and agriculture; and the legitimation of macroeconomic terminology by the large international organizations. Misapplications of macroeconomic analysis are identified, such as an erroneous equating of "macroeconomy" with "global economy". The lack of consensus among macroeconomic theorists about policies ostensibly based on macroeconomic analysis is discussed, as is the sometimes strained relationship between them and specialists

  12. Analysis of dynamic brain imaging data.

    PubMed Central

    Mitra, P P; Pesaran, B

    1999-01-01

    Modern imaging techniques for probing brain function, including functional magnetic resonance imaging, intrinsic and extrinsic contrast optical imaging, and magnetoencephalography, generate large data sets with complex content. In this paper we develop appropriate techniques for analysis and visualization of such imaging data to separate the signal from the noise and characterize the signal. The techniques developed fall into the general category of multivariate time series analysis, and in particular we extensively use the multitaper framework of spectral analysis. We develop specific protocols for the analysis of fMRI, optical imaging, and MEG data, and illustrate the techniques by applications to real data sets generated by these imaging modalities. In general, the analysis protocols involve two distinct stages: "noise" characterization and suppression, and "signal" characterization and visualization. An important general conclusion of our study is the utility of a frequency-based representation, with short, moving analysis windows to account for nonstationarity in the data. Of particular note are 1) the development of a decomposition technique (space-frequency singular value decomposition) that is shown to be a useful means of characterizing the image data, and 2) the development of an algorithm, based on multitaper methods, for the removal of approximately periodic physiological artifacts arising from cardiac and respiratory sources. PMID:9929474

  13. Nonlinear dynamic analysis of flexible multibody systems

    NASA Technical Reports Server (NTRS)

    Bauchau, Olivier A.; Kang, Nam Kook

    1991-01-01

    Two approaches are developed to analyze the dynamic behavior of flexible multibody systems. In the first approach each body is modeled with a modal methodology in a local non-inertial frame of reference, whereas in the second approach, each body is modeled with a finite element methodology in the inertial frame. In both cases, the interaction among the various elastic bodies is represented by constraint equations. The two approaches were compared for accuracy and efficiency: the first approach is preferable when the nonlinearities are not too strong but it becomes cumbersome and expensive to use when many modes must be used. The second approach is more general and easier to implement but could result in high computation costs for a large system. The constraints should be enforced in a time derivative fashion for better accuracy and stability.

  14. Dynamic asset trees and portfolio analysis

    NASA Astrophysics Data System (ADS)

    Onnela, J.-P.; Chakraborti, A.; Kaski, K.; Kertiész, J.

    2002-12-01

    The minimum spanning tree, based on the concept of ultrametricity, is constructed from the correlation matrix of stock returns and provides a meaningful economic taxonomy of the stock market. In order to study the dynamics of this asset tree we characterise it by its normalised length and by the mean occupation layer, as measured from an appropriately chosen centre called the `central node'. We show how the tree evolves over time, and how it shrinks strongly, in particular, during a stock market crisis. We then demonstrate that the assets of the optimal Markowitz portfolio lie practically at all times on the outskirts of the tree. We also show that the normalised tree length and the investment diversification potential are very strongly correlated.

  15. Crustal Dynamics Project data analysis, 1990

    NASA Technical Reports Server (NTRS)

    Caprette, D. S.; Ma, C.; Ryan, J. W.

    1990-01-01

    The Goddard Very Long Baseline Interferometry (VLBI) group reports the results of analyzing 1073 Mark 3 data sets acquired from fixed and mobile observing sites through the end of 1989 and available to the Crustal Dynamics Project. Two large solutions, GLB656 and GLB657, were used to establish a VLBI reference frame with an origin coincident with the ITRF89. Another large solution, GLB658, was used to obtain Earth rotation parameters, nutation offsets, and global source positions. Site velocities were obtained from another large solution, GLB659. A fifth large solution, GLB660, was used to obtain baseline evolution. Site positions are tabulated on a yearly basis from 1979 through 1992. Site velocities are presented in both Cartesian and topocentric coordinates. The results include 76 sources, 80 sites, and 422 baselines.

  16. Spectrum analysis with quantum dynamical systems

    NASA Astrophysics Data System (ADS)

    Ng, Shilin; Ang, Shan Zheng; Wheatley, Trevor A.; Yonezawa, Hidehiro; Furusawa, Akira; Huntington, Elanor H.; Tsang, Mankei

    2016-04-01

    Measuring the power spectral density of a stochastic process, such as a stochastic force or magnetic field, is a fundamental task in many sensing applications. Quantum noise is becoming a major limiting factor to such a task in future technology, especially in optomechanics for temperature, stochastic gravitational wave, and decoherence measurements. Motivated by this concern, here we prove a measurement-independent quantum limit to the accuracy of estimating the spectrum parameters of a classical stochastic process coupled to a quantum dynamical system. We demonstrate our results by analyzing the data from a continuous-optical-phase-estimation experiment and showing that the experimental performance with homodyne detection is close to the quantum limit. We further propose a spectral photon-counting method that can attain quantum-optimal performance for weak modulation and a coherent-state input, with an error scaling superior to that of homodyne detection at low signal-to-noise ratios.

  17. Dynamic mechanical analysis of fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Reed, K. E.

    1979-01-01

    Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens a transition was observed above the resin glass transition temperature which was manifested mechanically as an additional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass-rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus.

  18. Decision Analysis of Dynamic Spectrum Access Rules

    SciTech Connect

    Juan D. Deaton; Luiz A. DaSilva; Christian Wernz

    2011-12-01

    A current trend in spectrum regulation is to incorporate spectrum sharing through the design of spectrum access rules that support Dynamic Spectrum Access (DSA). This paper develops a decision-theoretic framework for regulators to assess the impacts of different decision rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, using sensing information between the transmitter and receiver of a communication link, provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. These results are useful to regulators and network developers in understanding in developing rules for future DSA regulation.