ORCID Profile
0000-0002-2462-8623
Current Organisation
University of Tasmania
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Publisher: Elsevier BV
Date: 09-2019
Publisher: Society of Economic Geologists
Date: 22-05-2015
Publisher: Elsevier BV
Date: 08-2006
Publisher: Wiley
Date: 09-2003
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2014
Publisher: Elsevier BV
Date: 12-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6JA00395H
Abstract: The production rates of polyatomic oxygen interferents (MO + /M + ) during LA-ICP-MS analysis were investigated in a range of silicate materials and metals.
Publisher: Universidad Nacional Autonoma de Mexico
Date: 04-2006
DOI: 10.22201/IGEOF.00167169P.2006.45.2.184
Abstract: Utilizamos la firma de isótopos estables de carbono, medida como δ¹³C, en la materia orgánica de suelo (SOM) como un método de alta resolución espacial para inferir algunos cambios ambientales durante el Pleistoceno tardío y el Holoceno en el valle de Teotihuacán. La interpretación se basa en la diferencia de δ¹³C y preferencias climáticas correspondientes de las plantas referidas como C3, C4 y CAM.Los valores de δ¹³C obtenidos de plantas que crecen en el valle hoy en día difieren claramente entre dos grupos: los de las plantas C3 con un promedio de -27%, y los de C4 y CAM con un promedio cerca de -13%. Los datos obtenidos para los suelos se encuentran en el intervalo de -25.72 a -15.54 %. Las secuencias de suelos Pleistoceno tardío- Reciente del valle alto (posición geomorfológica alta), localizadas en el perfil de Cerro Gordo, se caracterizan por una δ¹³C con poca variabilidad alrededor de -20%, indicando una coexistencia duradera entre las plantas C3 y C4 (y CAM). Las firmas más empobrecidas (-23 ± 2) %, dominadas por carbono derivado de la vegetación tipo C3, corresponden a los suelos de pantano del Pleistoceno tardío en el perfil retrógrado de transición Tepexpan del antiguo lago de Texcoco-Xaltocan. Los paleosuelos en el valle bajo (Pleistoceno tardío - Holoceno medio), incluyendo los de la Pirámide de la Luna, están menos empobrecidos (-17 ± 1) %, o bien, dominados por carbono de plantas C4 y CAM. Los suelos del Holoceno tardío y modernos presentan una disminución (1-2 %) respecto a las δ¹³C de los suelos subyacentes.A partir de las δ¹³C de suelos se estimó la porción relativa de la contribución de las plantas C4 a la materia orgánica del mismo. Nuestros resultados implican un incremento, dependiendo del lugar, de entre 10 y 70%, durante el período de transición entre el Pleistoceno tardío y Holoceno temprano, y un dominio de la vegetación tipo C4 en el ambiente del valle, hasta en un 84%, durante Holoceno medio. Nuestros datos apoyan la idea de un cambio natural de un clima más frío y húmedo durante el último Máximo Glacial y el Pleistoceno tardío a uno más seco y caluroso en el Holoceno medio. Un ligero incremento de humedad y establecimiento de un clima semejante al actual, aún cálido y seco, se infiere del incremento en todo el valle, dependiendo del lugar, de 4 a 10%, de la población de plantas C3. Sugerimos que este último cambio climático pudo favorecer el desarrollo de la antigua agricultura. Nuestra interpretación general de los primeros datos de isótopos estables del carbono concuerda con interpretaciones paleoambientales para el área basadas en registros palinológicos y paleolimnológicos en sedimentos lacustres.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2000
Publisher: Wiley
Date: 29-10-2021
DOI: 10.1111/GGR.12405
Abstract: Advances in laser ablation inductively coupled plasma‐mass spectrometry have improved analytical precision for mineral analysis, expanding geological interpretations from LA‐ICP‐MS results. However, with improvements in analytical precision, systematic errors from calibration can become more obvious and affect data quality. To improve the accuracy of the LA‐ICP‐MS technique, a fully quantified method is presented for the analysis of minerals with a CaCO 3 matrix. An in‐house calcite s le (P‐Cal) was developed with an independently constrained composition and compared with measurement results from LA‐ICP‐MS analysis, generated using multiple spot sizes, laser fluences and calibration methods. For many elements, calibration against NIST SRM 612 as a calibration reference material and USGS GSD‐1G and USGS BCR‐2G as secondary reference materials (calibration B) provided the best accuracy for CaCO 3 analysis. Ablation rates and element yield (ICP‐MS signal intensity in counts per second for a given isotope relative to the mass fraction of the respective element) in calcium carbonate closely resembles NIST SRM 612 however, the down‐hole fractionation curves of USGS BCR‐2G (basaltic glass matrix) are a better fit for carbonate. Variations in accuracy for measurements at different spot sizes are negligible compared with the other effects discussed. Additionally, ablation characteristics for powdered crystals versus large fragments produce a negligible effect on the accuracy of the results for calcium carbonate.
Publisher: Elsevier BV
Date: 2002
Publisher: MDPI AG
Date: 02-07-2021
DOI: 10.3390/GEOSCIENCES11070279
Abstract: Major trace element analyses, including pyrite chemistry of pyritic mudstones of shallow-marine Singa Formation of Pennsylvanian–Early Permian age have been carried out to assess gold potential, the source of sulfur and organic matter. Regionally, Singa Formation spatially correlates with the Bohorok Formation (Sumatra, Indonesia), the Kaeng Krachang group (Thailand), and the Lebyin group (Burma or Myanmar). In Southeast Asia, this formation is important because it has a record of glacial processes that occurred along the northern margin of Gondwana in the Late Paleozoic age. This study has revealed that mudstones of the Singa Formation, which contain lonestones of glacial origin, deposited under suboxic–oxic conditions in shallow marine environment during Pennsylvanian–Early Permian time. The black mudstones contain total organic carbon which ranges from 0.1 to 0.7 wt.%, and gold content varying from 40 to 62 ppb, making them gold source rocks. This study has revealed diagenetic gold presence in the early pyrite generations (pyrites 1, 2, and 3) in these mudstones with gold content ranging up to 1.6 ppm Au which is indicative of early enrichment of gold. Conversely, late generations of pyrite (pyrites 4, 5, and 6) in these mudstones record low gold content up to 0.5 ppm Au. The δ34S values for pyrite grains range from −24.6‰ to +6.2‰ likely indicate a combination of magmatic and biogenic source of sulfur. Organic carbon isotope composition of the pebbly mudstone s les shows a wide range from −23.9‰ to −5.8‰ indicating a mixed terrestrial and marine source.
Publisher: Society of Economic Geologists
Date: 13-07-2015
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 08-2001
Publisher: Springer Science and Business Media LLC
Date: 07-11-2017
DOI: 10.1038/S41467-017-01285-X
Abstract: Tractography based on non-invasive diffusion imaging is central to the study of human brain connectivity. To date, the approach has not been systematically validated in ground truth studies. Based on a simulated human brain data set with ground truth tracts, we organized an open international tractography challenge, which resulted in 96 distinct submissions from 20 research groups. Here, we report the encouraging finding that most state-of-the-art algorithms produce tractograms containing 90% of the ground truth bundles (to at least some extent). However, the same tractograms contain many more invalid than valid bundles, and half of these invalid bundles occur systematically across research groups. Taken together, our results demonstrate and confirm fundamental ambiguities inherent in tract reconstruction based on orientation information alone, which need to be considered when interpreting tractography and connectivity results. Our approach provides a novel framework for estimating reliability of tractography and encourages innovation to address its current limitations.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Wiley
Date: 07-09-2014
DOI: 10.1111/J.1472-8206.2012.01075.X
Abstract: Casiopeina III-Ea is a mixed chelate copper (II) complex that has shown cytotoxic and antitumor activity in vitro and in vivo. The aim of this study was to investigate the pharmacokinetics of total copper derived from casiopeina III-Ea administered by intravenous bolus injection to Wistar rats. Other objective was to evaluate the hematotoxicity produced by this compound in those animals. Wistar rats received a single intravenous dose of 4 mg/kg of casiopeina III-Ea. Blood s les were taken and pharmacokinetics evaluated. Furthermore, erythrocyte copper levels were determined to identify a potential target and Zn levels were analyzed to determine a possible change. For the evaluation of hematotoxicity, both blood and urine s les were collected for hematological and biochemical analyses moreover, Fe determination was performed. Blood copper and zinc levels, red blood cell copper levels as well as copper, zinc, and iron amounts excreted into urine were analyzed by ICP-MS. The blood concentration-time profile of copper derived from casiopeina III-Ea was fitted to a two-compartment model with a zero-order input. Cumulative amounts of Cu, Zn, and Fe excreted into rat urine after administration of casiopeina III-Ea were different with respect to control. Hematological and biochemical data indicated a hemolytic toxicity. Pharmacokinetic analysis of total copper derived from casiopeina III-Ea provided a general knowledge about distribution and elimination process of this compound. Additionally, the systemic exposure of the copper derived from casiopeina III-Ea accounts for the hematotoxicity of this complex at test dose.
Publisher: Wiley
Date: 22-12-2015
DOI: 10.1002/JCLP.22250
Publisher: Elsevier BV
Date: 06-2001
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3JA50070E
Publisher: Elsevier BV
Date: 03-2014
Publisher: Wiley
Date: 13-06-2023
DOI: 10.1111/GGR.12512
Abstract: A new reference material, STDGL3, for the calibration of in situ analyses of sulfide minerals by LA‐ICP‐MS has been developed and characterised. It represents a lithium‐borate‐based glass containing a mixture of Zn‐ and Fe‐sulfide concentrates doped with several chalcophile elements as well as Zr, Gd, Hf and Ta required for assessing common interferences on Ag, Au and Pt. STDGL3 has a wider range of elements and a better homogeneity compared with existing reference materials for LA‐ICP‐MS analysis of sulfides. Compositional variations for most elements are below 3% RSD, below 5% RSD for Ag, Au and Pt, and below 7% RSD for Se, when performing spot analyses with a 50 μm beam size. Its preparation recipe is reproducible allowing for multiple batches to be made. Use of STDGL3 significantly improves accuracy of sulfide mineral analysis by LA‐ICP‐MS when compared with use of other available reference materials. Performance of STDGL3 was evaluated using several different laser systems. No significant change was observed between 193 nm ArF excimer lasers with 5 and 20 ns pulse widths, but use of 213 and 248 nm lasers displays more systematic differences, especially when analysing galena. Correction coefficients are needed for some elements (Zn and Cd in particular) when analysing sulfide minerals using STDGL3 as a calibration reference material.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3JA50375E
Abstract: A method was tested for the digestion of SRM 1648a and airborne particulate s les using acid reflux before ICP-MS analysis of trace elements. The suitability of SRM 1648(a) as a reference material for airborne PM is discussed.
Publisher: Informa UK Limited
Date: 10-05-2023
Publisher: Elsevier BV
Date: 08-2011
Publisher: Geological Society of America
Date: 2002
Publisher: Wiley
Date: 08-01-2021
Location: Russian Federation
No related grants have been discovered for Elena Lounejeva.