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Chemical speciation

Austen L Davis, Brian H Clowers
Significant challenges exist when characterizing f-element complexes in solution using traditional approaches such as electrochemical and spectroscopic techniques as they do not always capture information for lower abundance species. However, provided a metal-complex with sufficient stability, soft ionization techniques such as electrospray offer a means to quantify and probe the characteristics of such systems using mass spectrometry. Unfortunately, the gas-phase species observed in ESI-MS systems do not always reflect the solution phase distributions due to the inherent electrochemical mechanism of the electrospray process, ion transfer from ambient to low pressures conditions, and other factors that are related to droplet evaporation...
January 1, 2018: Talanta
David Doran, Marc Rodriguez-Garcia, Rebecca Turk-MacLeod, Geoffrey J T Cooper, Leroy Cronin
We propose that a chemically agnostic approach to explore the origin of life, using an automated recursive platform based on droplet microfluidics, could be used to induce artificial chemical evolution by iterations of growth, speciation, selection, and propagation. To explore this, we set about designing an open source prototype of a fully automated evolution machine, comprising seven modules. These modules are a droplet generator, droplet transfer, passive and active size sorting, splitter, incubation chamber, reservoir, and injectors, all run together via a LabVIEW(TM) program integration system...
2017: Beilstein Journal of Organic Chemistry
Pierre Gueriau, Jean-Pascal Rueff, Sylvain Bernard, Josiane Albert Kaddissy, Sarah Goler, Christoph J Sahle, Dimosthenis Sokaras, Roy A Wogelius, Philip L Manning, Uwe Bergmann, Loïc Bertrand
Carbon compounds are ubiquitous and occur in a diversity of chemical forms in many systems including ancient and historic materials ranging from cultural heritage to paleontology. Determining their speciation cannot only provide unique information on their origin, but may also elucidate degradation processes. Synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the carbon K-edge (280-350 eV) is a very powerful method to probe carbon speciation. However, the short penetration depth of soft X-rays imposes stringent constraints on sample type, preparation and analytical environment...
September 13, 2017: Analytical Chemistry
Érika C P de Castro, Mika Zagrobelny, Márcio Z Cardoso, Søren Bak
Heliconiines are called passion vine butterflies because they feed exclusively on Passiflora plants during the larval stage. Many features of Passiflora and heliconiines indicate that they have radiated and speciated in association with each other, and therefore this model system was one of the first examples used to exemplify coevolution theory. Three major adaptations of Passiflora plants supported arguments in favour of their coevolution with heliconiines: unusual variation of leaf shape within the genus; the occurrence of yellow structures mimicking heliconiine eggs; and their extensive diversity of defence compounds called cyanogenic glucosides...
September 13, 2017: Biological Reviews of the Cambridge Philosophical Society
Virender K Sharma, Thomas J McDonald, Mary Sohn, George A K Anquandah, Maurizio Pettine, Radek Zboril
This paper reviews the current understanding of the toxicity of selenium (Se) to terrestrial mammalian and aquatic organisms. Adverse biological effects occur in the case of Se deficiencies, associated with this element having essential biological functions and a narrow window between essentiality and toxicity. Several inorganic species of Se (-2, 0, +4, and +6) and organic species (monomethylated and dimethylated) have been reported in aquatic systems. The toxicity of Se in any given sample depends not only on its speciation and concentration, but also on the concomitant presence of other compounds that may have synergistic or antagonistic effects, affecting the target organism as well, usually spanning 2 or 3 orders of magnitude for inorganic Se species...
August 26, 2017: Chemosphere
C S Oliveira, B C Piccoli, M Aschner, J B T Rocha
The antagonism of mercury toxicity by selenium has been well documented. Mercury is a toxic metal, widespread in the environment. The main target organs (kidneys, lungs, or brain) of mercury vary depending on its chemical forms (inorganic or organic). Selenium is a semimetal essential to mammalian life as part of the amino acid selenocysteine, which is required to the synthesis of the selenoproteins. This chapter has the aim of disclosing the role of selenide or hydrogen selenide (Se(-2) or HSe(-)) as central metabolite of selenium and as an important antidote of the electrophilic mercury forms (particularly, Hg(2+) and MeHg)...
2017: Advances in Neurobiology
Farimah Shirmohammadi, Christopher Lovett, Mohammad Hossein Sowlat, Amirhosein Mousavi, Vishal Verma, Martin M Shafer, James J Schauer, Constantinos Sioutas
To investigate the relative impacts of emissions from Los Angeles International Airport (LAX), as well as the impacts of traffic emissions from freeways, on the oxidative potential of particulate matter (PM), PM0.25 were collected at two urban background locations in Los Angeles. Redox activity of the PM samples was measured by means of an in vitro alveolar macrophage assay that quantifies the formation of reactive oxygen species (ROS) in cells, and detailed chemical analyses were performed to determine the speciated chemical composition of collected PM...
August 30, 2017: Science of the Total Environment
Catherine Berthomieu, Sandrine Sauge-Merle, Florian Brulfert, Romain Pardoux, Pier Lorenzo Solari, David Lemaire, Samir Safi, Philippe Guilbaud, Eric Simoni, Mohamed Larbi Merroun
Better understanding of uranyl-protein interactions is a prerequisite to predict uranium chemical toxicity in cells. The EF-hand motif of calmodulin site I is about thousand times more affine for uranyl than for calcium, and threonine phosphorylation increases uranyl affinity by two orders of magnitude at pH 7. In this study, we confront X-rays absorption spectroscopy with Fourier transform infrared (FTIR), time resolved laser-induced fluorescence spectroscopy (TRLFS) and structural models obtained by molecular dynamics simulations to analyze uranyl coordination in native and phosphorylated calmodulin site I...
September 4, 2017: Chemistry: a European Journal
Shusi Liu, Yixin Lu, Chen Yang, Chuanping Liu, Lin Ma, Zhi Dang
Biochar was carbon-rich and generated by high-temperature pyrolysis of biomass under oxygen-limited conditions. Due to the limitations of surface functional groups and the weakness of surface activity in the field of environmental remediation, the raw biochar frequently was chemically modified to improve its properties with a new performance. In this study, a kind of high-efficiency and low-cost amino biochar modified by nano zero-valent iron (ABC/NZVI) was synthesized and applied to paddy soil contaminated with arsenic (As)...
September 2, 2017: Environmental Science and Pollution Research International
Hendryk Czech, Toni Miersch, Jürgen Orasche, Gülcin Abbaszade, Olli Sippula, Jarkko Tissari, Bernhard Michalke, Jürgen Schnelle-Kreis, Thorsten Streibel, Jorma Jokiniemi, Ralf Zimmermann
Combustion technologies of small-scale wood combustion appliances are continuously developed decrease emissions of various pollutants and increase energy conversion. One strategy to reduce emissions is the implementation of air staging technology in secondary air supply, which became an established technique for modern wood combustion appliances. On that account, emissions from a modern masonry heater fuelled with three types of common logwood (beech, birch and spruce) and a modern pellet boiler fuelled with commercial softwood pellets were investigated, which refer to representative combustion appliances in northern Europe In particular, emphasis was put on the organic constituents of PM2...
August 31, 2017: Science of the Total Environment
Marco Grigatti, Elisa Boanini, Giampaolo Di Biase, Claudio Marzadori, Claudio Ciavatta
Composting is considered a suitable process for organic waste management, providing stable products that can be safely utilized as fertilizers, but little is still known about the variation of phosphorous (P) extractability during the stabilization process. In this work, sequential chemical extraction (SCE) with increasing strength extractants (H2O; 0.5M NaHCO3 pH 8.5; 0.1M NaOH, 1M HCl) was applied for P speciation over 56days of composting of either agro-industrial or urban wastewater sludge with green waste treated (AICFe+; SSCFe+) or not (AICFe-; SSCFe-) with FeSO4 (2%v/v)...
August 30, 2017: Waste Management
Frank Tawussi, Dharmendra K Gupta, Elena L Mühr-Ebert, Stephanie Schneider, Stefan Bister, Clemens Walther
Bioavailability and plant uptake of radionuclides depend on various factors. Transfer into different plant parts depends on chemical and physical processes, which need to be known for realistic ingestion dose modelling when these plants are used for food. Within the scope of the present work, the plutonium uptake by potato plants (Solanum tuberosum L.) was investigated in hydroponic solution of low concentration [Pu] = 10(-9) mol L(-1). Particular attention was paid to the speciation of radionuclides in the solution which was modelled by the speciation code PHREEQC...
August 30, 2017: Journal of Environmental Radioactivity
Susanne Sachs, Gerhard Geipel, Frank Bok, Jana Oertel, Karim Fahmy
Radioecological studies depend on the quantitative toxicity assessment of environmental radionuclides. In the low dose regime, the life span of affected organisms is barely shortened enabling the transfer of radionuclides through an almost intact food chain. Lethality-based toxicity estimates are not adequate in this regime because they require higher doses. In the case of radionuclides, increased dosage additionally alters radionuclide speciation, rendering the extrapolation to the low dose regime chemically inconsistent...
August 25, 2017: Environmental Science & Technology
Simon D Herzog, Per Persson, Emma S Kritzberg
Previous studies report high and increasing iron (Fe) concentrations in boreal river mouths. This Fe has shown relatively high stability to salinity-induced aggregation in estuaries. The aim of this study was to understand how the speciation of Fe affects stability over salinity gradients. For Fe to remain in suspension interactions with organic matter (OM) are fundamental and these interactions can be divided in two dominant phases: organically complexed Fe, and colloidal Fe (oxy)hydroxides, stabilized by surface interactions with OM...
August 24, 2017: Environmental Science & Technology
Ji-Eun Jung, Simona Liguori, Adam D Jew, Gordon E Brown, Jennifer Wilcox
One of the biggest environmental concerns caused by coal-fired power plants is the emission of mercury (Hg), which is toxic metal. To control the emission of Hg from coal-derived flue gas, it is important to understand the behavior, speciation of Hg as well as the interaction between Hg and solid materials in the flue gas stream. In this study, atomic-scale theoretical investigations using density functional theory (DFT) were carried out in conjunction with lab-scale experimental studies to investigate the adsorption behavior of Hg on hematite (?-Fe2O3)...
August 22, 2017: Journal of the Air & Waste Management Association
Wenchao Wei, Yanyan Zhang, Rachel Komorek, Andrew Plymale, Rujia Yu, Bingchen Wang, Zihua Zhu, Fanghua Liu, Xiao-Ying Yu
The aggregation of syntrophic Geobacter metallireducens and Geobacter sulfurreducens is beneficial for enhancing direct interspecies electron transfer (DIET). Although DIET was suspected to occur on the microbial community surface, the surface chemical speciation of such cocultured communities remains unclear. In order to better understand surface interactions related to DIET, the authors characterized a series of samples associated with syntrophic G. metallireducens and G. sulfurreducens using surface sensitive time-of-flight secondary ion mass spectrometry (ToF-SIMS)...
August 18, 2017: Biointerphases
David P Hopkins, Duncan D Cameron, Roger K Butlin
The diversity of phytophagous insects is largely attributable to speciation involving shifts between host plants. These shifts are mediated by the close interaction between insects and plant metabolites. However, there has been limited progress in understanding the chemical signatures that underlie host preferences. We use the pea aphid (Acyrthosiphon pisum) to address this problem. Host-associated races of pea aphid discriminate between plant species in race-specific ways. We combined metabolomic profiling of multiple plant species with behavioural tests on two A...
August 17, 2017: Scientific Reports
S Skanthakumar, Geng Bang Jin, Jian Lin, Valérie Vallet, L Soderholm
Seeking predictive insights into how metal-ion speciation impacts solution chemistry as well as the composition and structure of solid-precipitates, thorium correlations, with both solvent and other solute ions, were quantitatively probed in a series of acidic, nitrate/perchlorate solutions held at constant ionic strength. Difference pair-distribution functions (dPDF), obtained from high-energy X-ray scattering (HEXS) data, provide unprecedented structural information on the number of Th ligating ions in solution and how they change with increasing nitrate concentration...
August 30, 2017: Journal of Physical Chemistry. B
Chunshui Lin, Darius Ceburnis, Stig Michael Hellebust, Paul Buckley, John Charles Wenger, Francesco Canonaco, Andre S H Prevot, Ru-Jin Huang, Colin O'Dowd, Jurgita Ovadnevaite
An Aerosol Chemical Speciation Monitor (ACSM) was deployed to study the primary non-refractory submicron particulate matter emissions from burning of commercially available solid fuels (peat, coal, and wood) typically used in European domestic fuel stoves. Organic mass spectra (MS) from burning wood, peat, and coal were characterized and inter-compared for factor analysis against ambient data. The reference profiles characterized in this study were used to estimate the contribution of solid fuel sources, along with oil combustion, to ambient pollution in Galway, Ireland using the multilinear engine (ME-2)...
August 17, 2017: Environmental Science & Technology
Rüdiger Riesch, Moritz Muschick, Dorothea Lindtke, Romain Villoutreix, Aaron A Comeault, Timothy E Farkas, Kay Lucek, Elizabeth Hellen, Víctor Soria-Carrasco, Stuart R Dennis, Clarissa F de Carvalho, Rebecca J Safran, Cristina P Sandoval, Jeff Feder, Regine Gries, Bernard J Crespi, Gerhard Gries, Zach Gompert, Patrik Nosil
Speciation can involve a transition from a few genetic loci that are resistant to gene flow to genome-wide differentiation. However, only limited data exist concerning this transition and the factors promoting it. Here, we study phases of speciation using data from >100 populations of 11 species of Timema stick insects. Consistent with early phases of genic speciation, adaptive colour-pattern loci reside in localized genetic regions of accentuated differentiation between populations experiencing gene flow...
February 17, 2017: Nature ecology & evolution
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