1,721,081 research outputs found
Simple and efficient method to detach intact PM10 from field filters. Elements recovery assessment
No full textToxicity of the soluble fraction of particulate matter (PM) has been extensively evaluated, but it has also been demonstrated that insoluble aerosol species can considerably contribute to toxicological potential of PM. However, most of the procedures regarding the assessment of toxicological effects of the whole PM (soluble and insoluble species) requires targeted treatments of the sampled filters, such as the employment of organic solvents, or the application of ultrasounds. Both methods can introduce a bias in the toxicological assessment, altering PM oxidative potential and biological outcomes. In this study, we applied a non-invasive, simple and efficient method for the detachment of intact PM10 from field filters by using an electrical toothbrush, which allows obtaining a PM10 water-suspension to be used for PM toxicity assessment. The efficiency of this method was evaluated by comparing the elemental content (As, Ba, Bi, Ca, Co, Cs, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, U and W) obtained by brushing the filters to that measured by applying a conventional procedure to PM samples (n. 20 pairs of equivalent PM10 filters). Soluble and insoluble fractions were separately analyzed, in order to discriminate the recovery due to partial solubilization of sample from that due to detachment of insoluble particles. The high recovery percentage of elements, the very-high linear correlation coefficients and the low relative percentage differences with respect to a conventional procedure for elemental analysis of PM10 confirmed the efficiency of the toothbrush method
New Insights for Health and Environmental Impact Assessment of PM Released by Specific Emission Sources
Full text linkThis study is aimed to improve the knowledge about the association between health and environmental effects of particulate matter (PM) and its chemical composition and sources and it is focused on the integration of different observation systems and monitoring techniques. PM samples originated from different sources were collected and analyzed by traditional and innovative analytical methods, thus reaching a very detailed knowledge of their inorganic and organic chemical composition.
(A) Acellular assays: 1,4-dithiothreitol (DTT), ascorbic acid (AA) and 2',7'dichlorodihydrofluorescein (DCFH), able to give information about PM capacity to generate oxidative stress, were applied to PM-selected components to estimate the oxidative potential (OP) of PM released by different emission sources (A1). Plant and animal model organisms were exposed in vivo under controlled conditions to the PM-selected components. Oxidative stress and other biological responses were evaluated and correlated to the OP and chemical composition of PM and the reliability of the OP methods as proxies of the production of reactive oxygen (ROS) and nitrogen (RNS) species was assessed (A2, A3). Furthermore, the potential of NO to restore the cellular balance between the ROS and the RNS in the root system of a plant species exposed to As and Cd was evaluated (A4).
(B) To obtain valuable information for PM source apportionment and thus for the assessment of health and climate impact, a chemical/size fractionation method was applied to sampling campaigns carried out for seven consecutive years in the Po Valley (Northern Italy) (B1). PM10 and size-segregated PM samples collected in workplaces (B2) and in indoor environments of private dwellings (B3) were analyzed to investigate the health impact of particles emitted in different size fractions by specific indoor sources.
(C) Innovative and very-low volume samplers were used for high spatial resolution analyses of PM chemical components in the Terni basin (Central Italy), which can be considered as an open air laboratory for studying the spatial distribution of PM, since it is characterized by atmospheric stability and by the presence of several anthropic PM sources (C1, C2, C3). The impact of local emission sources was assessed and the spatial variability of PM element concentrations was mapped (C3) and compared with the results achieved by biomonitoring through lichen transplants (C4) and leaf deposition on riparian species (C5), to verify the reliability of biomonitoring techniques for the assessment of atmospheric element concentrations. The experimental approach, based on the mapping of spatially-resolved PM chemical data, is a powerful tool for a reliable assessment of population exposure to PM air pollutants and also promises to be effective for optimization and validation of dispersion models. This approach, combined with on-site human biomonitoring will allow further investigations on the relationships between health effects and PM chemical composition and sources.
(D) To investigate relationships between health effects and PM chemical composition and sources, the suitability of different biological matrixes for on-site human biomonitoring exposure to environmental pollution was evaluated. Rapid analytical methods for routine elemental analysis of a significant number of human hair samples were developed and validated (D1, D2). Moreover, Hg As, Pb and Cd levels in breast milk were assessed to provide valuable information on the maternal toxic load and to be used as an indicator for prenatal and post-natal exposure of infants to these chemicals. In addition, we assessed the capacity of a multi-strain probiotic to protect the infants from their exposure (D3).
(E) Finally, during the PhD research, environmental remediation techniques for inorganic and organic pollutants were investigated. The potential of food waste materials as low-cost adsorbents for the removal of toxic elements, heavy metals (E1) and volatile organic compounds (E2, E3) from wastewater was evaluated. The adsorption capacity of food waste materials was assessed by comparing the removal efficiency of elements and VOCs from complex solutions, maintaining homogeneous experimental conditions, which allowed us comparing the adsorption capacity of the individual sorbents
Innovative experimental approach for spatial mapping of source-specific risk contributions of potentially toxic trace elements in PM10
Full text linkExposure to potentially toxic trace elements (PTTEs) in inhalable particulate matter (PM10) is associated with an increased risk of developing cardiorespiratory diseases. Therefore, in multi-source polluted urban contexts, a spatially-resolved evaluation of health risks associated with exposure to PTTEs in PM is essential to identify critical risk areas. In this study, a very-low volume device for high spatial resolution sampling and analysis of PM10 was employed in Terni (Central Italy) in a wide and dense network (23 sampling sites, about 1 km between each other) during a 15-month monitoring campaign. The soluble and insoluble fraction of 33 elements in PM10 was analysed through a chemical fractionation procedure that increased the selectivity of the elements as source tracers. Total carcinogenic risk (CR) and non-carcinogenic risk (NCR) for adults and children due to concentrations of PTTEs in PM10 were calculated and quantitative source-specific risk apportionment was carried out by applying Positive Matrix Factorization (PMF) to the spatially-resolved concentrations of the chemically fractionated elements. PMF analysis identified 5 factors: steel plant, biomass burning, brake dust, soil dust and road dust. Steel plant showed the greatest risk contribution. Total CR and NCR, and source-specific risk contributions at the 23 sites were interpolated using the ordinary kriging (OK) method and mapped to geo-reference the health risks of the identified sources in the whole study area. This also allowed risk estimation in areas not directly measured and the assessment of the risk contribution of individual sources at each point of the study area. This innovative experimental approach is an effective tool to localize the health risks of spatially disaggregated sources of PTTEs and it may allow for better planning of control strategies and mitigation measures to reduce airborne pollutant concentrations in urban settings polluted by multiple sources
An optimized method for sample preparation and elemental analysis of extra-virgin olive oil by inductively coupled plasma mass spectrometry
Full text linkThe accurate determination of trace elements in vegetable edible oils is still an analytical challenge, owing to their low concentration levels and the complex matrix of the vegetable oils. The aim of this study was to develop a fast and simple analytical method to quantify 45 elements in small mass samples (0.5 g) of extra virgin olive oils by inductively coupled plasma mass spectrometry. To evaluate the best and fastest sample preparation procedure, ultrasonic extraction and wet digestion methods were compared using oil certified reference material with different reagent mixtures, reagent volumes, and times for sample extraction or digestion. The use of 5 mL reagent mixture F [10% (v/v) HNO3 and H2O2, 2:1 (v/v)] for sample digestion in a water bath (95 ◦C, 40 min) was found to produce satisfactory results in all cases as validated from sample recovery experiments over three
different extra virgin olive oil samples
Effects of operating conditions on PM oxidative potential assays
No full textOxidative potential (OP) has been suggested as a biologically relevant exposure metric for estimating particulate matter (PM) capacity to induce oxidative stress in living organisms. However, standardized experimental pro-cedures are not yet available. This study explores how a variety of operating conditions influences responses of several different assays for measuring OP: the 2′,7′-dichlorofluorescein (OPDCFH), the ascorbic acid (OPAA) and the dithiothreitol (OPDTT) assays. A recently optimized method for the evaluation of PM reducing properties, based on the 2,2-diphenyl-1-picrylhydrazyl assay (RPDPPH), was also included in the study. Two monitoring campaigns were carried out in Central Italy by using co-located PM10 samplers working in parallel, for comparing results obtained from different operating procedures simultaneously applied on equivalent samples. Extraction efficiency and repeatability of three different water-extraction methods (rotating agitator, ultra-sonic bath, and vortex), and the influence of storage duration and conditions on OP results were examined. OPDCFH values were found to be significantly higher when ultrasonic bath (US) was used for extraction, probably due to the formation of free radicals induced by US; for all the OP assays, the highest repeatability was obtained by extracting samples with rotating agitator (RA). Sample storage was confirmed to be a very critical issue as all the assays, except OPDTT, showed a marked dependence on storage time and conditions. The influence of membrane filters used to collect PM was also assessed. No significant differences were observed between samples collected on quartz and polytetrafluoroethylene (PTFE) membrane filters, except for OPAA, that gave significantly higher results for samples collected on PTFE membranes. Lastly, the contribution of water-insoluble PM com-ponents to OP was examined and warrants further investigations
An improved ring removal procedure for in-line x-ray phase contrast tomography
No full textThe suppression of ring artifacts in x-ray computed tomography (CT) is a required step in practical applications; it can be addressed by introducing refined digital low pass filters within the reconstruction process. However, these filters may introduce additional ringing artifacts when simultaneously imaging pure phase objects and elements having a non-negligible absorption coefficient. Ringing originates at sharp interfaces, due to the truncation of spatial high frequencies, and severely affects qualitative and quantitative analysis of the reconstructed slices. In this work, we discuss the causes of ringing artifacts, and present a general compensation procedure to account for it. The proposed procedure has been tested with CT datasets of the mouse central nervous system acquired at different synchrotron radiation facilities. The results demonstrate that the proposed method compensates for ringing artifacts induced by low pass ring removal filters. The effectiveness of the ring suppression filters is not altered; the proposed method can thus be considered as a framework to improve the ring removal step, regardless of the specific filter adopted or the imaged sample
Oxidative potential of particulate matter components generated by specific emission sources
No full textDifferent acellular assays are currently used for the determination of the oxidative potential (OP) of particular matter (PM). In order to better understand the existing correlations between OP and the PM generated by specific emission sources, dusts generated from seven different sources (urban dust, soil, road dust, brake dust, pellet ash, coke, and desert dust) were chemically characterized and analysed using three OP assays: dithiothreitol (DTT), acid ascorbic (AA) and 2′,7′-dichlorofluorescin (DCFH). In agreement with some previous literature studies, these assays provided very different results for each selected dust: their reliability as a proxy of ROS generation in biological system need then to be further investigated. When applied to the soluble fraction of these dusts, the DTT and AA assays were particularly sensitive toward pellet ash, while the highest OPDCFH values were measured for road dust. Multivariate analysis was used to confirm the correlations between the OP assay results and the chemical characteristics of the dust soluble fractions. DTT and AA assays appeared mostly influenced by organic and inorganic components, respectively. In the case of the DCFH assay, no clear correlations were highlighted, but, differently from the other assays, relevant OP values were measured also for dust of crustal origin. The insoluble fraction of the dusts, which is often not considered in this kind of study, generated, for all the considered assays, OP values even higher than those related to the soluble fraction. © 2018 Elsevier Lt
In-vacuum thermolysis of ethane 1,2-diamineborane for the synthesis of ternary borocarbonitrides
No full textHigh-temperature (1000°C) thermolytic decomposition of ethane 1,2-diamineborane
(BH3NH2CH2CH2NH2BH3) deposited onto a Cu foil has been performed in an ultra-highvacuum
environment. A combined thermolytic, structural (x-ray diffraction), microscopic
(scanning electron microscopy) and spectroscopic (Raman, x-ray photoemission spectroscopy)
analysis, has identified a ternary borocarbonitride (BCN) compound as a result of the process.
The obtained BCN compound is nanocrystalline, surrounded by crystallites of ammonium
hydroxide borate hydrate. The ternary compound presents a 0.2:0.6:0.2 B:C:N composition in
the bulk and 0.11:0.76:0.13 stoichiometry at the very surface, richer in C–C networks with
respect to the bulk. Furthermore, the resulting BCN compound does not show oxidation at the
surface due to the in-vacuum thermolysis of the single precursor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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