1,720,966 research outputs found
Flocculation of sewage sludge with FeCl3 modifies the bioavailability of potentially toxic elements when added to different soils
No full textThe effect of sewage sludge (SS) flocculation with FeCl3 on biological availability of Zn, Ni, Cd and Cu in oilseed rape (Brassica napus) plants grown on a acid and a neutral soil were studied during a greenhouse incubation experiment. The experiment included the following treatments: (i) unamended control soil, (ii) sewage sludge amended soils kept bare throughout the experiment and (iii) sewage sludge amended soil planted with oilseed rape. Amended soils received untreated or FeCl3 treated SS at a rate equivalent to 75 t d. w. ha-1 y-1.
Plant growth was enhanced by addition of both untreated and FeCl3 treated SS, but sludge treated with FeCl3 produced a lower shoot dry matter than untreated SS, particularly in the acid soil. Evaluation of biological availability of potentially toxic elements (PTE) was performed by three different methods: plant shoot analysis, single DTPA-extraction and sequential fractionation procedure (SEP). After 50 days, accumulation of PTE was considerably larger in plant shoots grown on the acid soil and amended with FeCl3 treated sludge. Conversely, the FeCl3 treated SS reduced Cd, Ni and Zn accumulation in shoots in the neutral soil. Copper was generally unaffected by SS treatment in both soils. Plants decreased significantly the DTPA-extractability of Cd, Ni and Zn in both soils that received Fe-SS, but they did not change it in soils that received untreated SS.
These different behaviours may be explained by the different mechanism involved in metals stabilization in the two soils: adsorption on Fe and Mn oxides in the neutral soil, precipitation and organic complexation in the acid soil.
The chemical flocculation treatment of waste water with FeCl3 reduces PTE availability in neutral soils amended with SS, but markedly increases their solubility and bio-availability in acid soils. Therefore, the application of SS obtained from flocculation with FeCl3 should be restricted to neutral or calcareous soils
Technical analysis and re-design of a screw log splitter: New methods of risk management
Full text linkIn the recent years, the proper design of agricultural machines for both professional and non-professional use has assumed a relevant role in workers protection and accident avoidance. The activities related to cutting and sawing of firewood is the main cause of injuries or death of the operator. This is often due to the use of inadequately built or modified machines, improper use of equipment and use of tools intended for other purposes. This study aimed to design a conical screw log splitter that meets the criteria of the European Directive 2006/42/EC and the technical standards of EN 609-2:1999+A1:2009(E) guideline. For a proper design we determined the forces that influence the machine during its use, and sized the machine accordingly. The log splitter was scanned and digitalized in three dimensions. From the digital model we obtained a real model in 5:1 scale. Comparing the created log splitter with other solutions available on the market we confirmed its similar costs with the costs of tools currently marketed. The productivity of the machine was only slightly lower than that of machines not equipped with protections, but its safety was significantly improve
New personal protective equipment for cutting and shearing: Finger-safe
Full text linkThe personal protective equipment used in agriculture does not include specific devices and due to this fact they are not able to provide a suitable degree of protection of the operator. In particular, the hand is the part of the body that is more prone to serious injury (e.g. amputation). The aim of this study was to test new safety principals for reducing the risk of cutting. We performed 10 types of different tests that led us to the identification of gloves resistant to mechanical action as well as to cutting. The prototype has demonstrated a high protective efficiency against tools such as pneumatic or manual scissors. In conclusion, the study recommends the use of gloves with elements which absorb and dissipate energy and not just simple cut resistant gloves. © 2015 Sirio R. S. Cividino et al
Bioaccumulation of polycyclic aromatic hydrocarbons and survival of earthworms (Eisenia andrei) exposed to biochar amended soils
No full textBiochar has a charcoal polycyclic aromatic structure which allows its long half-life in soil, making it an ideal tool for C sequestration and for adsorption of organic pollutants, but at the same time raises concerns about possible adverse impacts on soil biota. Two biochars were tested under laboratory-controlled conditions on Eisenia andrei earthworms: a biochar produced at low temperature from wine tree cuttings (WTB) and a commercial low tar hardwood lump charcoal (HLB). The avoidance test (48-h exposure) showed that earthworms avoid biochar-treated soil with rates higher than 16 t ha−1 for HLB and 64 t ha−1 for WTB. After 42 days, toxic effects on earthworms were observed even at application rates (100 t ha−1) that are generally considered beneficial for most crops. The concentration of HLB and WTB required to kill half of earthworms’ population (LC50; 95 % confidence limits) in the synthetic OECD soil was 338 and 580 t ha−1, respectively. Accumulation of polycyclic aromatic hydrocarbons (PAH) in earthworms exposed to the two biochar types at 100 t ha−1 was tested in two soils of different texture. In biochar-treated soils, the average earthworm survival rates were about 64 % in the sandy and 78 % clay-loam soils. PAH accumulation was larger in the sandy soil and largest in soils amended with HLB. PAH with less than four rings were preferentially scavenged from the soil by biochars, and this behaviour may mask that of the more dangerous components (i.e. four to five rings), which are preferentially accumulated. Earthworms can accumulate PAH as a consequence of exposure to biochar-treated soils and transfer them along the food chain. Soil type and biochar quality are both relevant in determining PAH transfer
Risk analysis of agricultural, forestry and green maintenance working sites
Full text linkThis work is focused on serious and fatal accidents which occur at forestry, agricultural and green maintenance working sites. In these sites are performed operations related to tree cutting or felling with continuous use of chainsaws. During this study we investigated 123 professional as well as non-professional working sites. We considered all characteristics necessary to determine the operating conditions and to identify possible steps for an effective protection. The work highlights a very serious situation in both investigated working environments where all measures of job safety are systematically ignored. In conclusion, we recommend that for a significant reduction of serious and fatal accidents, a mandatory training should be extended to all chainsaws users. Passive and active safety systems which interrupt the operation of the saw when it does not comply with all obligatory safety rules (i.e. human vicinity to cutting chain, falling down of the operator and others) should be define
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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