105 research outputs found

    Fast determination of thiacloprid by photoinduced chemiluminescence

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    This paper was published in Applied Spectroscopy and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/as/abstract.cfm?URI=as-68-6-642. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.A new and sensitive application of the chemiluminescence detection has been developed for the determination of the pesticide thiacloprid in water. It was based on the on-line photoreaction of thiacloprid in basic medium, with quinine acting as sensitizer of the chemiluminescent response; Cerium (IV) in sulfuric acid medium was used as oxidant. A high automation and reproducibility was provided by a flow injection analysis (FIA) manifold. The validation of the method was performed in terms of selectivity, linearity, LOD, precision and accuracy. Liquid chromatography with UV detection was used as reference for mineral, tap, ground and spring water samples. The proposed method is fast (throughput of 130 h-1), sensitive (LOD of 0.8 ng mL-1 without preconcentration steps and 0.08 ng mL-1 with solid phase extraction (SPE)), low-cost and possible to couple with separative methods for the simultaneous determination of other pesticides. The enhanced chemiluminescence intensity was linear with thiacloprid concentration over the (2-80) and (80-800) ng mL-1 ranges. A possible reaction mechanism is also discussed.The authors thank the Ministerio de Educacion y Ciencia of Spain and the Fondo Europeo de Desarrollo Regional for financial support, Project CTM2006-11991.Catalá Icardo, M.; López Paz, JL.; Pérez Plancha, LM. (2014). Fast determination of thiacloprid by photoinduced chemiluminescence. Applied Spectroscopy. 68(6):642-648. https://doi.org/10.1366/13-07330S642648686Tomizawa, M., & Casida, J. E. (2005). 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Chemosphere, 84(4), 464-470. doi:10.1016/j.chemosphere.2011.03.039Di Muccio, A., Fidente, P., Barbini, D. A., Dommarco, R., Seccia, S., & Morrica, P. (2006). Application of solid-phase extraction and liquid chromatography–mass spectrometry to the determination of neonicotinoid pesticide residues in fruit and vegetables. Journal of Chromatography A, 1108(1), 1-6. doi:10.1016/j.chroma.2005.12.111Fidente, P., Seccia, S., Vanni, F., & Morrica, P. (2005). Analysis of nicotinoid insecticides residues in honey by solid matrix partition clean-up and liquid chromatography–electrospray mass spectrometry. Journal of Chromatography A, 1094(1-2), 175-178. doi:10.1016/j.chroma.2005.09.012Seccia, S., Fidente, P., Barbini, D. A., & Morrica, P. (2005). Multiresidue determination of nicotinoid insecticide residues in drinking water by liquid chromatography with electrospray ionization mass spectrometry. Analytica Chimica Acta, 553(1-2), 21-26. doi:10.1016/j.aca.2005.08.006Pareja, L., Martínez-Bueno, M. J., Cesio, V., Heinzen, H., & Fernández-Alba, A. R. (2011). Trace analysis of pesticides in paddy field water by direct injection using liquid chromatography–quadrupole-linear ion trap-mass spectrometry. Journal of Chromatography A, 1218(30), 4790-4798. doi:10.1016/j.chroma.2011.02.044Seccia, S., Fidente, P., Montesano, D., & Morrica, P. (2008). Determination of neonicotinoid insecticides residues in bovine milk samples by solid-phase extraction clean-up and liquid chromatography with diode-array detection. Journal of Chromatography A, 1214(1-2), 115-120. doi:10.1016/j.chroma.2008.10.088Wang, W., Li, Y., Wu, Q., Wang, C., Zang, X., & Wang, Z. (2012). Extraction of neonicotinoid insecticides from environmental water samples with magnetic graphene nanoparticles as adsorbent followed by determination with HPLC. Analytical Methods, 4(3), 766. doi:10.1039/c2ay05734dBi, X., & Yang, K.-L. (2009). On-Line Monitoring Imidacloprid and Thiacloprid in Celery Juice Using Quartz Crystal Microbalance. Analytical Chemistry, 81(2), 527-532. doi:10.1021/ac801786aGámiz-Gracia, L., Garcı́a-Campaña, A. M., Soto-Chinchilla, J. J., Huertas-Pérez, J. F., & González-Casado, A. (2005). Analysis of pesticides by chemiluminescence detection in the liquid phase. TrAC Trends in Analytical Chemistry, 24(11), 927-942. doi:10.1016/j.trac.2005.05.009Roda, A., & Guardigli, M. (2011). Analytical chemiluminescence and bioluminescence: latest achievements and new horizons. Analytical and Bioanalytical Chemistry, 402(1), 69-76. doi:10.1007/s00216-011-5455-8Du, J., & Li, H. (2010). Sensitive Chemiluminescence Determination of Thirteen Cephalosporin Antibiotics with Luminol—Copper(II) Reaction. Applied Spectroscopy, 64(10), 1154-1159. doi:10.1366/000370210792973613Li, Y., Li, Y., & Yang, Y. (2011). Flow-Injection Chemiluminescence Determination of Lisinopril Using Luminol–KMnO4 Reaction Catalyzed by Silver Nanoparticles. Applied Spectroscopy, 65(4), 376-381. doi:10.1366/10-06115Catalá-Icardo, M., López-Paz, J. L., Choves-Barón, C., & Peña-Bádena, A. (2012). Native vs photoinduced chemiluminescence in dimethoate determination. Analytica Chimica Acta, 710, 81-87. doi:10.1016/j.aca.2011.10.043Mestre, Y. F., Zamora, L. L., & Calatayud, J. M. (2001). Flow-chemiluminescence: a growing modality of pharmaceutical analysis. Luminescence, 16(3), 213-235. doi:10.1002/bio.608Lara, F. J., García-Campaña, A. M., & Aaron, J.-J. (2010). Analytical applications of photoinduced chemiluminescence in flow systems—A review. Analytica Chimica Acta, 679(1-2), 17-30. doi:10.1016/j.aca.2010.09.001Icardo, M. C., & Calatayud, J. M. (2008). Photo-Induced Luminescence. Critical Reviews in Analytical Chemistry, 38(2), 118-130. doi:10.1080/10408340802039609RICART, I., ANTONFOS, G., DUART, M., MATEO, J., ZAMORA, L., & CALATAYUD, J. (2007). Theoretical prediction of the photoinduced chemiluminescence of pesticides. Talanta, 72(2), 378-386. doi:10.1016/j.talanta.2006.10.048Abramović, B. F., Banić, N. D., & Šojić, D. V. (2010). Degradation of thiacloprid in aqueous solution by UV and UV/H2O2 treatments. Chemosphere, 81(1), 114-119. doi:10.1016/j.chemosphere.2010.07.016Icardo, M. (2003). FI-on line photochemical reaction for direct chemiluminescence determination of photodegradated chloramphenicol. Talanta, 60(2-3), 405-414. doi:10.1016/s0039-9140(03)00074-2Zhao, Y., Baeyens, W. R. G., Zhang, X., Calokerinos, A. C., Nakashima, K., & Der Weken, G. V. (1997). Chemiluminescence Determination of Tiopronin by Flow Injection Analysis Based on Cerium(IV) Oxidation Sensitized by Quinine. The Analyst, 122(2), 103-106. doi:10.1039/a605703iZhang, Z., Baeyens, W. R. G., Zhang, X., Zhao, Y., & Van Der Weken, G. (1997). Chemiluminescence detection coupled to liquid chromatography for the determination of penicillamine in human urine. Analytica Chimica Acta, 347(3), 325-332. doi:10.1016/s0003-2670(97)00171-2Capitán-Vallvey, L. (2000). Chemiluminescence determination of sodium 2-mercaptoethane sulfonate by flow injection analysis using cerium(IV) sensitized by quinine. Talanta, 51(6), 1155-1161. doi:10.1016/s0039-9140(00)00291-5NIE, L., MA, H., SUN, M., LI, X., SU, M., & LIANG, S. (2003). Direct chemiluminescence determination of cysteine in human serum using quinine–Ce(IV) system. Talanta, 59(5), 959-964. doi:10.1016/s0039-9140(02)00649-5Lakowicz, J. R. (Ed.). (2006). Principles of Fluorescence Spectroscopy. doi:10.1007/978-0-387-46312-4Lookabaugh, M., & Krull, I. S. (1988). Determination of nitrite and nitrate by reversed-phase high-performance liquid chromatography using on-line post-column photolysis with ultraviolet absorbance and electrochemical detection. Journal of Chromatography A, 452, 295-308. doi:10.1016/s0021-9673(01)81454-0Gómez-Benito, C., Meseguer-Lloret, S., & Torres-Cartas, S. (2013). Sensitive determination of Fenamiphos in water samples by flow injection photoinduced chemiluminescence. International Journal of Environmental Analytical Chemistry, 93(2), 152-165. doi:10.1080/03067319.2012.663755CATALÁ-ICARDO, M., LÓPEZ-PAZ, J. L., & PEÑA-BÁDENA, A. (2011). FI-photoinduced Chemiluminescence Method for Diuron Determination in Water Samples. Analytical Sciences, 27(3), 291. doi:10.2116/analsci.27.291Hamilton, D. J., Ambrus, Á., Dieterle, R. M., Felsot, A. S., Harris, C. A., Holland, P. T., … Wong, S.-S. (2003). Regulatory limits for pesticide residues in water (IUPAC Technical Report). Pure and Applied Chemistry, 75(8), 1123-1155. doi:10.1351/pac20037508112

    Is current management of the Antarctic krill fishery in the Atlantic sector of the Southern Ocean precautionary?

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    This paper explains the management of the Antarctic krill (Euphausia superba) fishery in the Atlantic sector of the Southern Ocean, and current knowledge about the state of the regional krill stock. In this region, krill fishing is permitted in an area of approximately 3.5 million km2 which is divided into four subareas (labelled Subareas 48.1 to 48.4) for management and reporting purposes. The effective regional catch limit (or ‘trigger level’), established in 1991, is 0.62 million tonnes year–1, equivalent to ~1% of the regional biomass estimated in 2000. Each subarea has also had its own catch limit, between 0.093 and 0.279 million tonnes year–1, since 2009. There is some evidence for a decline in the abundance of krill in the 1980s, but no evidence of a further decline in recent decades. Local-scale monitoring programs have been established in three of the subareas to monitor krill biomass in survey grids covering between 10 000 and 125 000 km2. Cautious extrapolation from these local monitoring programs provides conservative estimates of the regional biomass in recent years. This suggests that fishing at the trigger level would be equivalent to a long-term exploitation rate (annual catch divided by biomass) of <7%, which is below the 9.3% level considered appropriate to maintain the krill stock and support krill predators. Subarea catch limits exceed 9.3% of conservatively estimated subarea biomass in up to 20% of years due to high variability in krill biomass indices. The actual exploitation rate in each subarea has remained <3% because annual catches have been <50% of the trigger level since 1991. Comparison with the 9.3% reference exploitation rate suggests that current management is precautionary at the regional scale. The subarea catch limits help prevent excessive concentration of catch at the subarea scale. Finer-scale management might be necessary to manage the risk of adverse impacts which might occur as a result of concentrated fishing in sensitive areas or climate change. Frequent assessment of the krill stock will enhance CCAMLR’s ability to manage these risks. Continuing the local monitoring programs will provide valuable information on krill variability, but more information is required on how the monitored biomass relates to biomass at the subarea and regional scales

    Shear yielding of amorphous glassy solids: Effect of temperature and strain rate

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    We study shear yielding and steady state flow of glassy materials with molecular dynamics simulations of two standard models: amorphous polymers and bidisperse Lennard-Jones glasses. For a fixed strain rate, the maximum shear yield stress and the steady state flow stress in simple shear both drop linearly with increasing temperature. The dependence on strain rate can be described by a either a logarithm or a power-law added to a constant. In marked contrast to predictions of traditional thermal activation models, the rate dependence is nearly independent of temperature. The relation to more recent models of plastic deformation and glassy rheology is discussed, and the dynamics of particles and stress in small regions is examined in light of these findings

    Space-time Phase Transitions in Driven Kinetically Constrained Lattice Models

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    Kinetically constrained models (KCMs) have been used to study and understand the origin of glassy dynamics. Despite having trivial thermodynamic properties, their dynamics slows down dramatically at low temperatures while displaying dynamical heterogeneity as seen in glass forming supercooled liquids. This dynamics has its origin in an ergodic-nonergodic first-order phase transition between phases of distinct dynamical "activity". This is a "space-time" transition as it corresponds to a singular change in ensembles of trajectories of the dynamics rather than ensembles of configurations. Here we extend these ideas to driven glassy systems by considering KCMs driven into non-equilibrium steady states through non-conservative forces. By classifying trajectories through their entropy production we prove that driven KCMs also display an analogous first-order space-time transition between dynamical phases of finite and vanishing entropy production. We also discuss how trajectories with rare values of entropy production can be realized as typical trajectories of a mapped system with modified forces

    Shear-banding in a lyotropic lamellar phase, Part 1: Time-averaged velocity profiles

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    Using velocity profile measurements based on dynamic light scattering and coupled to structural and rheological measurements in a Couette cell, we present evidences for a shear-banding scenario in the shear flow of the onion texture of a lyotropic lamellar phase. Time-averaged measurements clearly show the presence of structural shear-banding in the vicinity of a shear-induced transition, associated to the nucleation and growth of a highly sheared band in the flow. Our experiments also reveal the presence of slip at the walls of the Couette cell. Using a simple mechanical approach, we demonstrate that our data confirms the classical assumption of the shear-banding picture, in which the interface between bands lies at a given stress σ\sigma^\star. We also outline the presence of large temporal fluctuations of the flow field, which are the subject of the second part of this paper [Salmon {\it et al.}, submitted to Phys. Rev. E]

    Fluctuation-dissipation relations in the non-equilibrium critical dynamics of Ising models

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    We investigate the relation between two-time, multi-spin, correlation and response functions in the non-equilibrium critical dynamics of Ising models in d=1 and d=2 spatial dimensions. In these non-equilibrium situations, the fluctuation-dissipation theorem (FDT) is not satisfied. We find FDT `violations' qualitatively similar to those reported in various glassy materials, but quantitatively dependent on the chosen observable, in contrast to the results obtained in infinite-range glass models. Nevertheless, all FDT violations can be understood by considering separately the contributions from large wavevectors, which are at quasi-equilibrium and obey FDT, and from small wavevectors where a generalized FDT holds with a non-trivial limit fluctuation-dissipation ratio X. In d=1, we get X = 1/2 for spin observables, which measure the orientation of domains, while X = 0 for observables that are sensitive to the domain-wall motion. Numerical simulations in d=2 reveal a unique X = 0.34 for all observables. Measurement protocols for X are discussed in detail. Our results suggest that the definition of an effective temperature Teff = T / X for large length scales is generically possible in non-equilibrium critical dynamics.Comment: 26 pages, 10 figure

    Early Jurassic palaeoenvironments in the Surat Basin, Australia - marine incursion into eastern Gondwana

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    Interpretations of palaeodepositional environments are important for reconstructing Earth history. Only a few maps showing the Jurassic depositional environments in eastern Australia currently exist. Consequently, a detailed understanding of the setting of Australia in Gondwana is lacking. Core, wireline logs, two‐dimensional and three‐dimensional seismic from the Precipice Sandstone and Evergreen Formation in the Surat Basin have been used to construct maps showing the evolution of depositional environments through the Early Jurassic. The results indicate the succession consists of three third‐order sequences (Sequence 1 to Sequence 3) that were controlled by eustatic sea level. The lowstand systems tract in Sequence 1 comprises braidplain deposits, confined to a fairway that parallels the basin centre. The strata were initially deposited in two sub‐basins, with rivers flowing in different orientations in each sub‐basin. The transgressive systems tract of Sequence 1 to lowstand systems tract of Sequence 3 is dominated by fluvio–deltaic systems infilling a single merged basin centre. Finally, the transgressive and highstand systems tracts of Sequence 3 show nearshore environments depositing sediment into a shallow marine basin. In the youngest part of this interval, ironstone shoals are the most conspicuous facies, the thickness and number of which increase towards the north and east. This study interprets a corridor to the open ocean through the Clarence–Moreton Basin, or the Carpentaria and Papuan basins, evidence of which has been eroded. These results challenge a commonly held view that eastern Australia was not influenced by eustasy, and propose a more dynamic palaeogeographic setting comprising a mixture of fluvial, deltaic and shallow marine sedimentary environments. This work can be used to unravel the stratigraphic relationships between Mesozoic eastern Australian basins, or in other basins globally as an analogue for understanding the complex interplay of paralic depositional systems in data poor areas

    Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

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    <div><p>ABSTRACT: The Rio Grande do Sul (RS) coastal plain area (33,000 km 2 ) had its physiography modified several times through the Quaternary, responding to allogenic and autogenic forcings. The Patos Lagoon covers a significant area of RS coastal plain (10,000 km 2 ), where incised valleys were identified in previous works. About 1,000 km of high resolution (3.5 kHz) seismic profiles, radiocarbon datings, Standard Penetration Test (SPT) and gravity cores were analyzed to interpret the paleoenvironmental evolution as preserved in incised valley infills. Seismic facies were recognized by seismic parameters. The sediment cores were used to ground-truth the seismic interpretations and help in the paleoenvironmental identification. Key surfaces were established to detail the stratigraphical framework, and seismic facies were grouped into four seismic units, which one classified in respective system tracts within three depositional sequences. The oldest preserved deposits are predominantly fluvial and estuarine facies, representing the falling stage and lowstand system tracts. The Holocene transgressive records are dominated by muddy material, mainly represented by estuarine facies with local variations. The transgression culminated in Late Holocene deposits of Patos Lagoon, representing the highstand system tract. The depositional pattern of the vertical succession was controlled by eustatic variations, while the autogenic forcing (paleogeography and sediment supply) modulated the local facies variation.</p></div
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