Street dust and soil are important materials for evaluating the contaminants level in industrial areas. Detailed size-resolved distribution of metal(loid)s in street dusts and soils influenced by ...industrial activities has rarely been investigated. This study was carried out to understand how industrialization might affect the size distribution of metal(loid)s concentration and contamination level in the street dust and soil from Murcia, southern Spain. An industrial and a natural areas were selected and surface soil and street dust samples were taken. They were fractionated into eleven size classes and total concentrations of Pb, Zn, Cu, Cd, Cr, Ni, As and Fe were determined in both the bulk samples and their fractions. Enrichment factor, geoaccumulation index, and mass loading of different heavy metal(loids) were calculated. The results indicated that the street dust from natural and industrial areas had almost the same particle size distribution, both containing higher percentage of coarse-sized particles than the soil. Industrialization seems to have only slightly affected the concentration of most elements studied in the soil. In contrast, the concentrations of the heavy elements in bulk industrial dust samples and all their size fractions were extremely higher than those from the natural area. This means that the industrial activities only affected the size dependency of the concentration (contamination level) of certain elements (Pb, Zn, Cu, Cd, and Cr) in the street dust, but not in the soil.
Display omitted
•Industrialization has slightly affected the level of most metal(loid)s in urban soils.•Street dust size fractions have been more highly influenced by industrialization.•The concentrations of Pb, Zn, Cu, Cd and Cr are size dependent in industrial dust.•The degree of enrichment with elements in soils is not very much size dependent.•Size fractionation seems to be only needed in moderately to highly contaminated areas.
Water scarcity in arid and semiarid regions poses problems for agricultural systems, awakening special interest in the development of deficit irrigation strategies to improve water conservation. ...Toward this purpose, farmers and technicians must monitor soil water and soluble nutrient contents in real time using simple, rapid and economical techniques through time and space. Thus, this study aimed to achieve the following: (i) create a model that predicts water and soluble nutrient contents in soil profiles using electrical resistivity tomography (ERT); and (ii) apply the model to different woody crops under different irrigation regimes (full irrigation and regulated deficit irrigation (RDI)) to assess the efficiency of the model. Simple nonlinear regression analysis was carried out on water content and on different ion contents using electrical resistivity data as the dependent variable. A predictive model for soil water content was calibrated and validated with the datasets based on exponential decay of a three-parameter equation. Nonetheless, no accurate model was achieved to predict any soluble nutrient. Electrical resistivity images were replaced by soil water images after application of the predictive model for all studied crops. They showed that under RDI situations, soil profiles became drier at depth while plant roots seemed to uptake more water, contributing to reductions in soil water content by the creation of desiccation bulbs. Therefore, the use of ERT combined with application of the validated predictive model could be a sustainable strategy to monitor soil water evolution in soil profiles under irrigated fields, facilitating land irrigation management.
Background
Word retrieval skills change across the lifespan. Permanent alterations in the form of decreased accuracy or increased response time can be a consequence of both normal ageing processes or ...the presence of acquired and neurodegenerative disorders (e.g., aphasia and dementia). Despite the extensive literature exploring the neuroanatomical underpinnings of word retrieval, psycholinguistic, biolinguistic and theoretical explanations, and the vast amount of evidence from primary and secondary language disorders, the best approach to consistently capture these changes is yet to be discovered.
Aims
The goal of this paper is to determine which method(s) stand(s) as the most suitable candidate(s) to provide an accurate picture of word retrieval in the oral production of different groups of adult speakers, including cases of healthy ageing, preclinical Alzheimer's disease (AD), mild cognitive impairment (MCI), aphasia and dementia.
Methods & Procedures
Using an integrative review of recent peer‐reviewed journal articles, we provide an overview of the different behavioural methods traditionally used to measure oral naming skills in research‐oriented and clinical protocols and discuss their main advantages and limitations.
Main Contribution
Most existing studies are based on the results of people with diagnosed language disorders. Despite the growing interest, the reliability of the majority of the tasks to detect subtle changes associated with healthy ageing, MCI and preclinical AD are yet to be demonstrated, and the delicate balance between informativeness and efficiency (especially in terms of administration time and variable control) in experimental protocols is yet to be achieved. In this article we propose the pursuit of an integrative overarching methodology to characterize all naming deficits (from anecdotal to permanent) and all adult populations (from healthy to pathological ageing).
Conclusions & Implications
A combination of spontaneous speech data and results from structured tasks stands as the best approach to capture changes in word retrieval skills of adult speakers with and without observable deficits. This review can guide future reflections on the necessary prerequisites of purpose‐oriented, sensitive and reliable protocols for the detection of incipient word retrieval problems, thus contributing to the early diagnosis and the design of personalized multicomponent treatments.
WHAT THIS PAPER ADDS
What is already known on this subject
Word retrieval skills change during adulthood as a consequence of the neurological degradation associated with ageing. These changes are more dramatic in the event of acquired and neurodegenerative disorders. Numerous studies based on people with observable language disorders have addressed the multiplicity of factors involved in word retrieval and provided evidence of potential loci of impairment from a neuroanatomical, cognitive and/or (psycho‐)linguistic perspective.
What this paper adds to existing knowledge
This study focuses on methodological strategies to assess naming skills and provides a reflection on generally accepted good practices and unresolved challenges to inform task selection, emphasizing the necessity for a combination of methods to best capture the actual problems and needs of people confronting word retrieval difficulties in their daily lives. Task selection, variable control and administration time stand as key concepts to adjust to the requirements of research and clinical contexts.
What are the potential or actual clinical implications of this work?
The results of this review can orient future research towards the creation of sensitive, reliable and (ecologically) valid materials for the (early) detection of word retrieval deficits and for the customization of treatment protocols to alleviate or palliate their effects.
In virtual learning communities, becomes evident the need to generate methods of analysing social networks to investigate participation and the exchange of knowledge. Big data, and more specifically ...educational data mining and learning analytics, allows deepening the study of the learning process in these virtual contexts. In this article, the objective is to analyse the applicability and the validity of the Pareto principle in the field of online education. This classical principle, also called the 20/80 rule, describes the causes and effects of certain variables and proportions. Its fulfilment has been demonstrated in very diverse fields.
Based on reticular analysis for the detection of communication patterns and generation of knowledge in online learning communities, and using the Pareto Principle, the article studies the correlation between academic results and the exchange of knowledge. From a sample of 184 members of the university community (between students and teaching staff) and 1354 messages, the correspondence is established by analysing, on the one hand, the qualifications and, on the other hand, the participation and monitoring of the interactions produced in the communication spaces made available to students in the classroom.
Some of the results obtained are summarized in the following points:
• Difficulty in predicting grades obtained from classroom activity.
• The Forum is shown as an essential element of activity in the classroom.
• The reading of messages in the Forum is concentrated in the first days of the course activity.
• Exists a relationship between the obtained qualification and the monitoring of classroom communication spaces.
• High qualifications do not correspond to the level of participation.
•Pareto Principle has been applied to learning communities.•The Forum is the space with the most significant number of reading messages.•Message reading is concentrated in a few days.•Exists a correlation between grades and interaction.•High qualifications don't depend only on the activity in the virtual classroom.
Background: The study aimed to determine the apparent total tract digestibility coefficients (ATTDC) of nutrients, the apparent metabolizable energy (AME and AMEn) and the amino acid (AA) apparent ...ileal digestibility coefficients (AIDC)of a partially defatted (BSFp) and a highly defatted (BSFh) black soldier fly larvae meal. The experimental diets were: a basal diet and two diets prepared by substituting 250 g/kg (w/w) of the basal diet with BSFp or BSFh, respectively.Results: Significant differences were found between BSFp and BSFh meals for ATTDC of the nutrients: BSFp resulted more digestible than BSFh, except for ATTDC of CP which did not differed between meals, while a statistical trend was observed for ATTDC of DM and EE. The AME and AMEn values were significantly (P < 0.05) different between the two BSF meals, with higher levels for BSFp (16.25 and 14.87 MJ/kg DM, respectively). The AIDC of the AA in BSFp ranged from 0.44 to 0.92, while in BSFh they ranged from 0.45 to 0.99. No significant differences were observed for the AA digestibility (0.77 and 0.80 for BSFp and BSFh, respectively), except for glutamic acid, proline and serine that were more digestible in the BSFh meal (P < 0.05).Conclusions: Defatted BSF meals can be considered as an excellent source of AME and digestible AA for broilers with a better efficient nutrient digestion. These considerations suggested the effective utilization of defatted BSF larvae meal in poultry feed formulation.
Vegetarian and vegan diets have increased worldwide in the last decades, according to the knowledge that they might prevent coronary heart disease, cancer, and type 2 diabetes. Althought plant-based ...diets are at risk of nutritional deficiencies such as proteins, iron, vitamin D, calcium, iodine, omega-3, and vitamin B12, the available evidence shows that well planned vegetarian and vegan diets may be considered safe during pregnancy and lactation, but they require a strong awareness for a balanced intake of key nutrients. A review of the scientific literature in this field was performed, focusing specifically on observational studies in humans, in order to investigate protective effects elicited by maternal diets enriched in plant-derived foods and possible unfavorable outcomes related to micronutrients deficiencies and their impact on fetal development. A design of pregestational nutrition intervention is required in order to avoid maternal undernutrition and consequent impaired fetal growth.
Several sequential extraction procedures are widely applied for metals chemical fractionation in the literature. However, their limitations to be used in different soils and metals have not been ...discussed in detail. This study compares two of the most commonly used extraction methods for metals chemical fractionation: Tessier and BCR. The objectives were to i) assess the differences between concentrations of metals extracted in each fraction by both Tessier and BCR procedures; ii) elucidate if soil properties affected the extraction ability of each fraction from both procedures; and iii) evaluate how land use contributes to different chemical metal distribution. Results indicated that both methods provide similar results when were applied to the same soil, since non-significant differences were found in metal concentrations between both methods at each fraction. Conversely, when we compared among land uses, significant differences were found in the metal concentration between both methods, especially between agricultural/urban/industrial against forest soil. Redundancy analysis showed that in carbonate-rich soils, BCR extraction method could cover up the real concentration of exchangeable metals with those bound to the carbonate phase, being the Tessier method the most suitable one for this kind of soils. Therefore, although sequential extraction is a useful tool to understand the distribution of metals in soil, the method used must be selected according to the land use and specific soil characteristics, taking into account at least, soil carbonate content.
•Sequential extraction is an useful tool to stablish differences in metal distribution among land uses.•Metal fractionation among land uses depends on the metal concentration.•BCR method can cover up the real behaviour of the exchangeable fraction in calcareous soils.
Mining activity in Cartagena‐La Union mining district (SE Spain) dates back more than 2500 years. Consequently, large amounts of sterile materials with large metal(loid) contents (mostly Zn and Pb) ...have accumulated in tailings ponds. A reclamation strategy based on aided phytostabilization was carried out to reclaim one tailings pond to reduce environmental and public health hazards. The main goal of this study was to determine the effectiveness of the aided phytostabilization strategy after 30 months from its implementation in enhancing soil quality and fertility and reducing mobility of the metals. Marble waste, raw pig slurry and its solid phase after physical separation were applied as amendments, and 13 Mediterranean native plant species were planted or sown. Various soil physicochemical and biochemical properties, together with the pseudo‐total and bioavailable fraction of the metal(loid)s, As, Cd, Cu, Pb and Zn, were monitored for 30 months. Results showed that pH, total organic carbon (TOC), total nitrogen (TN), cation exchange capacity (CEC), available phosphorus (P), exchangeable potassium (K), microbial biomass carbon (MBC), basal soil respiration (BSR) and enzyme activities increased with the application of the amendments and development of vegetation. In addition, the available fraction of metals markedly decreased (90–99%). Most plant species present in the area did not transfer large amounts of trace elements to the aerial tissues. The roots of Lygeum spartum loefl. Ex L. and Piptatherum miliaceum (L.) Coss. accumulated the largest amounts of As, Pb and Zn. Thus, the application of marble waste to increase pH and immobilize metal(loid)s, and pig slurry as a source of organic matter and nutrients, together with the development of vegetation to immobilize metal(loid)s in the roots and rhizosphere, and the effect of microbial communities on organic matter stabilization and development, have contributed to improve soil quality and fertility. Once the soil quality of mine tailings was improved, the development of vegetation and microbial colonization increased, promoting integrated reclamation of the area. Therefore, aided phytostabilization was a suitable technique for remediation of this tailings pond.
Highlights
We evaluated effectiveness of mid‐term and large‐scale aided phytostabilization.
Marble waste, pig slurry and native plants were used for reclamation of a tailings pond.
Increased soil quality promoted plant development and microbial colonization.
Lygeum spartum and Piptatherum miliaceum are good candidates to phytostabilize Pb, Zn and As.
The versatility and potential applications of additive manufacturing have accelerated the development of additive/subtractive hybrid manufacturing methods. LPBF processes are exceptionally efficient ...at producing complex-shaped, thin-walled, hollow, or slender parts; however, finishing machining operations are necessary to ensure part assembly and surface quality. Rapid solidification during LPBF processes generates columnar grain structures in alloys. This is associated with crystalline textures and anisotropy, and therefore, mechanical properties are highly dependent on space directions, thus affecting cutting force and its variability.
In this study, theoretical and experimental analyses examined the effects of LPBF parameters on cutting forces and the anisotropy of alloys. Therefore, an oblique cutting Taylor based model was proposed to quantify the crystallographic effects on the shear strength. For this, the tool geometry, tool position, and laser scanning strategy were considered along with the microstructures, crystallographic textures and grain morphologies of two samples with different layer thicknesses (low-volumetric energy density (VED) and high-VED) using scanning electron microscopy and electron backscatter diffraction. Peripheral milling operations had been performed under 54 experimental conditions to evaluate the interactions between the machining parameters along with the layer thickness and the microstructural characteristics of printed alloys. The analysis revealed a significant interaction between the direction of the plane of the shear band and the grain orientation along the main axis. Three milling configurations were evaluated. The effects of the layer thickness on the evolution of the cutting force were elucidated. Additionally, the low-VED sample exhibited higher anisotropy in the cutting force compared to the high-VED one. The anisotropy in the latter corresponds to a high, dense ring-like texture; however, the crystallographic effect is lower in the low-VED sample. A good correlation between the cutting force fluctuation and the predicted Taylor factor was obtained. Lastly, the grain boundary density was acceptably correlated with the level of cutting force for both the printed cases.
Display omitted
•Correlation between directional dependency of the measured milling force response and crystallographic effect is quantified.•Tool-test piece relative position and grain refining interaction is evaluated.•Cutting forces are reduced for low volumetric energy density (VED)fabrications (grain refining) when tool axis and grain major axis are parallel.•A correlation between cutting force levels and grain boundary density is observed.
Atmospheric particulates play a vital role in the transport of potentially toxic metals, being an important exposure pathways of people to toxic elements, which is faster and can occur in a much ...larger scale than water, soil and biota transport. Windblown materials in abandoned tailing ponds have not been well examined. The objectives of this investigation were: to study the major physical and geochemical properties of the materials eroded by wind inside the tailing ponds, and to understand the relative contribution of different sources to its heavy metals concentration. Study area is located in Cartagena-La Union mining district (SE Spain), where metallic mining of Fe, Pb and Zn has been developed for more than 2500 years. Wind-eroded particulates were monthly collected at 3 different heights (20, 50, and 80 cm) from the ground for a period of a full year using 4 dust collectors. Four tailing samples and 4 surface soil samples from the surrounding hills were also taken. Dust, soil, and tailing samples were examined for pH, particle size distribution, electrical conductivity, calcium carbonate content, Pb, Cu, Zn, Cd, Mn, Co, Ni, Ti and Zr concentrations. The results indicated that very coarse textured, slightly saline, and almost neutral wind-eroded deposits were generated with a very high temporal variability throughout the year. They also showed that the concentration of Cd, Mn, Pb and Zn, in the dust samples is extraordinarily high (18, 1254, 1831, and 5747 mg kg−1 respectively), whereas Co, Ni, and Cu had concentrations into the range of background concentrations found in the Earth's crust (3.8, 12, and 60 mg kg−1 respectively). Besides, the concentration of both categories of heavy metals in the dust samples was higher than that in tailing and less than that of the soils. The barren surfaces of tailing ponds and also the surface soils of the surrounding area seem to be the major contributors to the dust collected. Therefore, abandoned mines as well as their tailing ponds should be rehabilitated by proper technologies and then well stabilized and/or covered by appropriate plant vegetation to control the transfer, particularly by air, of environmentally hazardous materials to other areas.
Display omitted
•Substantial quantity of dust is generated in the abandoned tailing ponds.•Deposition rate of aeolian particulates has very much temporal variability.•Wind eroded materials are mostly coarse-sized, similar to the surrounding soils and tailings.•The concentration of Cd, Zn, Mn, and Pb in the dust samples is extremely high.•Based on all the properties, tailings and local soils are the major sources of dust.
PDF
