922 resultados para elemental analysis
Resumo:
This research uses scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and inductively coupled plasma-mass spectrometry (ICP-MS) on cross-sections of iron artifacts sectioned from along shafts to determine the elemental constituents of a collection of Inuit and European artifacts from along the coast of Labrador. Hand-wrought iron nails from early historic period (16th – 18th centuries CE) Inuit sites in Labrador were originally manufactured by and acquired from early whalers and fishers of various European nationalities. The purpose of this research was to assess if the elements in different samples are sufficiently homogeneous to be viable for a provenience analysis to discern which Inuit nails were originally derived from which European groups; the Basque, English or French. The consistent relationships between the geochemical signatures of iron nails found in Inuit sites and historic nails derived from specific European groups could provide insights into the prevalence, activity and the nature of indigenous interactions of different European nationalities in the region over time. The results show that the methods applied to evaluate the geochemistry of the nails was not sufficient to detect meaningful patterns because the nails did not demonstrate the necessary degree of chemical uniformity among different samples in the same artifacts.
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An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150–1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65–0.68 respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data compared with 85% and 15% respectively for BC estimated from the aethalometer model. On average, the mass size distribution for EC particles is bimodal; the smaller mode is attributed to locally emitted, mostly externally mixed EC particles, while the larger mode is dominated by aged, internally mixed ECOCNOx particles associated with continental transport events. Periods of continental influence were identified using the Lagrangian Particle Dispersion Model (LPDM) "FLEXPART". A consistent minimum between the two EC mass size modes was observed at approximately 400 nm for the measurement period. EC particles below this size are attributed to local emissions using chemical mixing state information and contribute 79% of the scaled ATOFMS EC particle mass, while particles above this size are attributed to continental transport events and contribute 21% of the EC particle mass. These results clearly demonstrate the potential benefit of monitoring size-resolved mass concentrations for the separation of local and continental EC emissions. Knowledge of the relative input of these emissions is essential for assessing the effectiveness of local abatement strategies.
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The gross changes in concentrations of several trace elements in seawater after contact with ferro-manganese particle suspensions has been determined. Cobalt, Fe, and Zn concentrations in the seawater were greatly increased after contact with the par¬ticles. The concentrations of Rb, U, Cs, Sb, and Ag were altered to a lesser degree by this treatment. Similar results were observed where seawater was con¬tacted with suspensions of pelagic sediments. Of the trace elements measured, cobalt and iron appear to be the best elemental indicators of the presence of manganese mining effluents in the ocean. The addi¬tions of the essential elements Co, Fe and Zn toge¬ther with nutrients from the bottom waters may pro¬duce increased biological productivity. However, the toxic trace metals, such as Hg, Cu and Cd which could enter ocean water from the nodules and sedi¬ment and which may be high in effluent-affected areas should be investigated before conclusions as to the likely impact can be reached. Trace element analysis of seawater samples collected at a Pacific Ocean manganese nodule dredging site showed high t race element concentrations, but these are believed to have resulted from contamination during sample collection or storage rather than from the dredging operations.
Resumo:
Manganese nodules have been observed over wide areas of both the Pacific and Atlantic Oceans, however, deposits in the Pacific Ocean are generally much richer in elements of economic interest such as nickel, copper and cobalt. In understanding the genesis and the geochemistry involved in their formation and growth, it is important to know the total chemical composition of these nodules and how they vary within a given deposit and between deposits in the oceans of the world. The concentrations of elements: nickel, copper, cobalt, iron, manganese, silicon, and calcium, in all of the manganese nodules which have been analyzed were recently summarized by Horn et al. (1972). These observations indicate certain correlations, both positive and negative, between Mn and the associated elements within the nodules. Their data suggest similarities in chemical composition for nodules from a given area; however, the analyses of Mn nodules, like that of the ocean water, itself, has large errors associated with some of the measurements. This is understandable, since many of these measurements were intended to provide an approximate indication of elemental content. Where one is interested in carefully preparing a description of Mn nodule chemical composition which can serve as a basis for formulating theories regarding their genesis and subsequent geochemical changes in the ocean environment, then very precise and accurate analyses are essential. The purpose of this study has been to measure the concentrations of 18 elements in Mn nodules with a high degree of accuracy and determine what correlations exist between element concentrations. The scope of this study was seriously limited and therefore was confined to one area of the Pacific Ocean at approximately 22 N latitude, 114 W longitude, at an ocean depth of approximately 11,000 feet.
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A compositional multivariate approach is used to analyse regional scale soil geochemical data obtained as part of the Tellus Project generated by the Geological Survey Northern Ireland (GSNI). The multi-element total concentration data presented comprise XRF analyses of 6862 rural soil samples collected at 20cm depths on a non-aligned grid at one site per 2 km2. Censored data were imputed using published detection limits. Using these imputed values for 46 elements (including LOI), each soil sample site was assigned to the regional geology map provided by GSNI initially using the dominant lithology for the map polygon. Northern Ireland includes a diversity of geology representing a stratigraphic record from the Mesoproterozoic, up to and including the Palaeogene. However, the advance of ice sheets and their meltwaters over the last 100,000 years has left at least 80% of the bedrock covered by superficial deposits, including glacial till and post-glacial alluvium and peat. The question is to what extent the soil geochemistry reflects the underlying geology or superficial deposits. To address this, the geochemical data were transformed using centered log ratios (clr) to observe the requirements of compositional data analysis and avoid closure issues. Following this, compositional multivariate techniques including compositional Principal Component Analysis (PCA) and minimum/maximum autocorrelation factor (MAF) analysis method were used to determine the influence of underlying geology on the soil geochemistry signature. PCA showed that 72% of the variation was determined by the first four principal components (PC’s) implying “significant” structure in the data. Analysis of variance showed that only 10 PC’s were necessary to classify the soil geochemical data. To consider an improvement over PCA that uses the spatial relationships of the data, a classification based on MAF analysis was undertaken using the first 6 dominant factors. Understanding the relationship between soil geochemistry and superficial deposits is important for environmental monitoring of fragile ecosystems such as peat. To explore whether peat cover could be predicted from the classification, the lithology designation was adapted to include the presence of peat, based on GSNI superficial deposit polygons and linear discriminant analysis (LDA) undertaken. Prediction accuracy for LDA classification improved from 60.98% based on PCA using 10 principal components to 64.73% using MAF based on the 6 most dominant factors. The misclassification of peat may reflect degradation of peat covered areas since the creation of superficial deposit classification. Further work will examine the influence of underlying lithologies on elemental concentrations in peat composition and the effect of this in classification analysis.
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This paper is part of a special issue of Applied Geochemistry focusing on reliable applications of compositional multivariate statistical methods. This study outlines the application of compositional data analysis (CoDa) to calibration of geochemical data and multivariate statistical modelling of geochemistry and grain-size data from a set of Holocene sedimentary cores from the Ganges-Brahmaputra (G-B) delta. Over the last two decades, understanding near-continuous records of sedimentary sequences has required the use of core-scanning X-ray fluorescence (XRF) spectrometry, for both terrestrial and marine sedimentary sequences. Initial XRF data are generally unusable in ‘raw-format’, requiring data processing in order to remove instrument bias, as well as informed sequence interpretation. The applicability of these conventional calibration equations to core-scanning XRF data are further limited by the constraints posed by unknown measurement geometry and specimen homogeneity, as well as matrix effects. Log-ratio based calibration schemes have been developed and applied to clastic sedimentary sequences focusing mainly on energy dispersive-XRF (ED-XRF) core-scanning. This study has applied high resolution core-scanning XRF to Holocene sedimentary sequences from the tidal-dominated Indian Sundarbans, (Ganges-Brahmaputra delta plain). The Log-Ratio Calibration Equation (LRCE) was applied to a sub-set of core-scan and conventional ED-XRF data to quantify elemental composition. This provides a robust calibration scheme using reduced major axis regression of log-ratio transformed geochemical data. Through partial least squares (PLS) modelling of geochemical and grain-size data, it is possible to derive robust proxy information for the Sundarbans depositional environment. The application of these techniques to Holocene sedimentary data offers an improved methodological framework for unravelling Holocene sedimentation patterns.
Resumo:
We consider the a posteriori error analysis and hp-adaptation strategies for hp-version interior penalty discontinuous Galerkin methods for second-order partial differential equations with nonnegative characteristic form on anisotropically refined computational meshes with anisotropically enriched elemental polynomial degrees. In particular, we exploit duality based hp-error estimates for linear target functionals of the solution and design and implement the corresponding adaptive algorithms to ensure reliable and efficient control of the error in the prescribed functional to within a given tolerance. This involves exploiting both local isotropic and anisotropic mesh refinement and isotropic and anisotropic polynomial degree enrichment. The superiority of the proposed algorithm in comparison with standard hp-isotropic mesh refinement algorithms and an h-anisotropic/p-isotropic adaptive procedure is illustrated by a series of numerical experiments.
Resumo:
ANTECEDENTES.- Las infecciones de vías urinarias son causadas por bacterias, hongos y parásitos a nivel mundial.1Esta investigación se realizó en los habitantes de la comunidad de Sarapamba Yutuloma. OBJETIVO.- Determinar la prevalencia de infección de vías urinarias y sus factores asociados en los habitantes de la comunidad de Sarapamba Yutuloma Tambo. METODOLOGÍA.- La investigación fue de tipo descriptivo transversal, se trabajó con un universo de 280 habitantes de la comunidad. El tamaño de la muestra fue calculada con la fórmula finita con un nivel de confiabilidad del 95%.el resultado de la población a estudiar fue de 180 habitantes. Los participantes de esta investigación firmaron o colocaron su huella digital en el consentimiento informado en mayores o asentimiento para menores de edad, personas analfabetas o discapacitadas, llenaron una encuesta que han sido elaborados en base al modelo de Vigilancia STEPS de los factores de riesgo de enfermedades crónicas no transmisibles de la OMS 2010 aplicado en Suiza. Las muestras fueron recolectadas bajo normas de Bioseguridad, estas fueron procesadas en el Laboratorio del Centro de Diagnóstico de la Facultad de Ciencias Médicas de la Universidad de Cuenca. La información obtenida se registró en los programas, SPSS V 22 y Excel para hacer el análisis y las estadísticas. RESULTADOS.- El 16,1% de los habitantes de Sarapamba Yutuloma tiene infección del tracto urinario, el 86,2% son mujeres, el 13,8 son varones, 72,4% en edades comprendidas entre 22 y 53 años y el 89,9% al mantener actividad sexual.
Resumo:
Antecedentes: La infección del tracto urinario es una de las patologías más comunes y forma parte de las principales causas de consulta médica y hospitalización. (1, 2) Es frecuente en mujeres, personas con vida sexual activa, mujeres embarazadas y diabéticos. El 10 al 20 % de mujeres entre los 18 y 40 años experimentan infección del tracto urinario, en hombres mayores a 50 años se asocia a problemas por hiperplasia prostática y en personas de la tercera edad la frecuencia es similar tanto en hombres como en mujeres. (1) Objetivo: Identificar infección de vías urinarias mediante el examen elemental y microscópico de orina en los habitantes de la comuna Sunicorral Tambo- Cañar 2015. Metodología: Estudio de tipo descriptivo transversal en habitantes la comuna Sunicorral, la muestra fue de 202 personas. Luego firmar del consentimiento y asentimiento informado, se llenó las encuesta con información relacionada a las variables de estudio, se recolectaron las muestras de orina y el análisis se realizó en el laboratorio del Centro de Diagnóstico de la Universidad de Cuenca, los datos obtenidos fueron analizado en el programa SPSS y Microsoft Excel y presentados en tablas y gráficos estadísticos. Resultados: De 202 muestras el 15% reportó infección del tracto urinario, el 87,1% fue mujer, el 25,8% correspondió a la edad de 10 a 19 años, el 64,6% realizó su higiene intima pasando uno o más días, el 62,0% tiene actividad sexual siendo un factor importante.
Resumo:
Antecedentes: La infección de vías urinarias corresponde a la invasión de microorganismos a los tejidos que conforman el tracto urinario, a cualquier nivel, la sintomatología depende del sitio y localización de la infección (1). Las mujeres debido a que su uretra es más corta que en los hombres tienen mayor probabilidad de contraer una Infección de vías urinarias (IVU) (2). Objetivo: Identificar la infección de vías urinarias, mediante el examen elemental y microscópico de orina, en los habitantes de la comunidad de Caguanapamba Tambo Cañar. Metodología: El estudio fue de tipo descriptivo de corte transversal, se realizó en la comunidad de Caguanapamba perteneciente al Cantón El Tambo, el universo lo constituyeron los 361 habitantes de la comunidad, según el documento de planificación territorial del cantón, la muestra estuvo representada por 186 personas quienes firmaron el consentimiento informado en donde se informó todo el proceso a seguir en la investigación, luego se aplicó una encuesta, que recopiló información relacionada con los datos de filiación y las variables consideradas de estudio. Las muestras fueron recolectadas bajo normas de calidad y bioseguridad a fin de garantizar los resultados. El procesamiento de las mismas se realizó en el Laboratorio del Centro de Diagnóstico de la Universidad de Cuenca. Para el análisis de resultados se utilizó los programas SPSS V22 Y Microsoft Excel, para la estadística descriptiva se utilizaron tablas y gráficos
Resumo:
The common two-banded sea bream (Diplodus vulgaris) is an important fish in the marine ecosystems of the NW Atlantic and Mediterranean. In southern Portugal it is a major fishery resource being targeted mainly by the artisanal fleets. Although there is some knowledge of the age, growth and reproductive biology of the species, information about its population structure is scarce and somewhat limited to the Mediterranean Sea. In this study the otolith elemental signatures of 90 specimens of D. vulgaris of the same age group (2+ years) and cohort collected from the important fishery regions of SW Portugal (Sesimbra, Sagres and Faro) have been analysed by inductively coupled plasma mass spectrometry (ICP-MS). Two different methodologies have been applied: solution based analysis of the whole otoliths; representative of the entire life-history prior to capture, and laser ablation analysis of otolith cores; representative of the larval and early post-settlement phase. Whole otolith comparisons utilised Sr/Ca, Ba/Ca, Mn/Ca, Li/Ca and Ni/Ca to demonstrate regional population structure. Classification accuracy rates from linear discriminant function analyses (LDFA) of whole otolith chemistry data were high for each region; Faro - 93%, Sagres - 90% and Sesimbra - 80%. Comparison of the otolith core chemistry utilised Sr/Ca, Ba/Ca, Mn/Ca and Mg/Ca and Zn/Ca. LDFA for the otolith core chemistry also achieved accurate classification for samples from Sesimbra (73%), but there was high overlap of otolith chemistry between samples from Faro and Sagres (47 and 43% classification accuracy respectively). The whole otolith results suggest that D. vulgaris are resident in the regional fishing areas during the juvenile phase. Both the core and whole otolith chemistry data supported separation of the Sesimbra fishery region from the more southern and closely associated Faro and Sagres regions for management purposes. However, while the whole otolith data indicated that the populations at Faro and Sagres likely remained separated in the juvenile stage, the otolith core chemistry data was inconclusive as to whether recruitment to these two areas was derived, or not, from different spawning areas.
Resumo:
The study and preservation of museum collections requires complete knowledge and understanding of constituent materials that can be natural, synthetic, or semi-synthetic polymers. In former times, objects were incorporated in museum collections and classified solely by their appearance. New studies, prompted by severe degradation processes or conservation-restoration actions, help shed light on the materiality of objects that can contradict the original information or assumptions. The selected case study presented here is of a box dating from the beginning of the 20th century that belongs to the Portuguese National Ancient Art Museum. Museum curators classified it as a tortoiseshell box decorated with gold applications solely on the basis of visual inspection and the information provided by the donor. This box has visible signs of degradation with white veils, initially assumed to be the result of biological degradation of a proteinaceous matrix. This paper presents the methodological rationale behind this study and proposes a totally non-invasive methodology for the identification of polymeric materials in museum artifacts. The analysis of surface leachates using 1H and 13C nuclear magnetic resonance (NMR) complemented by in situ attenuated total reflection infrared spectroscopy (ATR FT-IR) allowed for full characterization of the object s substratum. The NMR technique unequivocally identified a great number of additives and ATR FT-IR provided information about the polymer structure and while also confirming the presence of additives. The pressure applied during ATR FT-IR spectroscopy did not cause any physical change in the structure of the material at the level of the surface (e.g., color, texture, brightness, etc.). In this study, variable pressure scanning electron microscopy (VP-SEM-EDS) was also used to obtain the elemental composition of the metallic decorations. Additionally, microbiologic and enzymatic assays were performed in order to identify the possible biofilm composition and understand the role of microorganisms in the biodeterioration process. Using these methodologies, the box was correctly identified as being made of cellulose acetate plastic with brass decorations and the white film was identified as being composed mainly of polymer exudates, namely sulphonamides and triphenyl phosphate.