Extractability and mobility of mercury from agricultural soils surrounding industrial and mining contaminated areas

This study focussed on a comparison of the extractability of mercury in soils with two different contamination sources (a chlor-alkali plant and mining activities) and on the evaluation of the influence of specific soil properties on the behaviour of the contaminant. The method applied here did not target the identification of individual species, but instead provided information concerning the mobility of mercury species in soil. Mercury fractions were classified as mobile, semi-mobile and non-mobile. The fractionation study revealed that in all samples mercury was mainly present in the semi-mobile phase (between 63 and 97%). The highest mercury mobility (2.7 mg kg-1) was found in soils from the industrial area. Mining soils exhibited higher percentage of non-mobile mercury, up to 35%, due to their elevated sulfur content. Results of factor analysis indicate that the presence of mercury in the mobile phase could be related to manganese and aluminum soil contents. A positive relation between mercury in the semi-mobile fraction and the aluminium content was also observed. By contrary, organic matter and sulfur contents contributed to mercury retention in the soil matrix reducing the mobility of the metal. Despite known limitations of sequential extraction procedures, the methodology applied in this study for the fractionation of mercury in contaminated soil samples provided relevant information on mercury's relative mobility

The antimicrobial properties of Moringa oleifera Lam. for water treatment: a systematic review

Plant extracts have been used as alternatives to the conventional chemical water treatment. Moringa oleifera Lam. is one of the plants used for this purpose due to its antimicrobial and coagulant properties. However, there is no systematization of Moringa’s application methodology. Different parts of the plant, extraction methods and concentrations can be applied to remove several pathogens present in contaminated drinking water. In the present work, reported Moringa applications with antimicrobial effect were systematically reviewed, in order to identify effective methodology(ies) for water treatment. Forty-nine articles were screened for: (1) part of the plant used, (2) extraction method, (3) extract concentration, (4) targeted pathogens, and (5) inhibition zone obtained. Nine articles complied with these criteria and were carefully analyzed; eight of them reported on leaf extracts and only one on seed extracts. Two approaches were used: analysis by pathogen and overall analysis. A total of eight different extraction methods were reported. Extract concentrations used ranged from 0.02 to 800 mg mL−1 and were tested on twenty pathogens. Our analysis revealed that none of such methods is effective against all the tested pathogens. However, leaf extracts obtained with distilled water or with 95% ethanol were the most effective ones for a higher number of pathogens such as Escherichia coli and, possibly, Vibrio cholerae. Moreover, Moringa’s extract concentration of 30 mg mL−1 obtained by the 95% ethanol extraction method was the most efficient. Findings suggest an effective procedure to use Moringa, reinforcing its importance as an environmentally friendly alternative for water treatment in areas lacking a water supply system.info:eu-repo/semantics/publishedVersio

A supramolecular zigzag chain of organometallic dipoles mediated by PF6 2- anions

Complex {Fe( 5-cyclopentadienyl)(PMe3)[P(OPh)3](4–NCC6H4NO2)} [PF6] has been characterized by spectroscopic and X-ray diffraction in order to evaluate the tuning of the electron density at the metal center and the extension ofthe delocalization on the molecule due to the presence of phosphite and phosphine co-ligands. The compound crystallizes in the centrosymmetric space group P21/c which destroys the possibility of exhibiting any quadratic NLO properties. The packing shows a supramolecular zigzag chain of antiparalell dimmers connected via the PF6 anions with C—H—F −distances ranging from 2.389 (7) to 2.667 (6)°A . Each zigzag chain is composed by isomeric organometallic fragments containing either R or S molecules. These chains are connected through weak intermolecular interactions (C—H· · ·C) forming a two dimensional plane along [101]

A supramolecular zigzag chain of organometallic dipoles mediated by PF6 2- anions

Complex {Fe( 5-cyclopentadienyl)(PMe3)[P(OPh)3](4–NCC6H4NO2)} [PF6] has been characterized by spectroscopic and X-ray diffraction in order to evaluate the tuning of the electron density at the metal center and the extension ofthe delocalization on the molecule due to the presence of phosphite and phosphine co-ligands. The compound crystallizes in the centrosymmetric space group P21/c which destroys the possibility of exhibiting any quadratic NLO properties. The packing shows a supramolecular zigzag chain of antiparalell dimmers connected via the PF6 anions with C—H—F −distances ranging from 2.389 (7) to 2.667 (6)°A . Each zigzag chain is composed by isomeric organometallic fragments containing either R or S molecules. These chains are connected through weak intermolecular interactions (C—H· · ·C) forming a two dimensional plane along [101]

Curved layer path planning on a 5-axis 3D printer

Article publication date: 7 October 2021Purpose – This paper aims to provide an approach to print shell-type objects using a 5-axis printer. The proposed approach takes advantage of the two additional printer degrees of freedom to provide a curved layer path planning strategy. Design/methodology/approach – This paper addresses curved layer path planning on a 5-axis printer. This printer considers movements along the three usual axes together with two additional axes at the printing table (rotation and tilt), allowing to build more complex and reliable objects. Curved layer path planning is considered where polygons obtained from the slicing stage are approximated by linear and cubic splines. The proposed printing strategy consists in building an inner core supporting structure followed by outer curved layers. Findings – The curved layer path planning strategy is validated for shell-type objects by considering a 5-axis printer simulator. An example with an aeronautic object is presented to illustrate the proposed approach. Originality/value – The paper presents an approach to curved layer path planning on a 5-axis printer, for shell-type objects.This work was developed under the FIBR3D project Hybrid processes based on additive manufacturing of composites with long or short fibers reinforced thermoplastic matrix (POCI-01-0145-FEDER-016414), supported by the Lisbon Regional Operational Programme 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)

Dexamethasone prevents granulocyte-macrophage colony-stimulating factor-induced nuclear factor-kappaB activation, inducible nitric oxide synthase expression and nitric oxide production in a skin dendritic cell line.

AIMS: Nitric oxide (NO) has been increasingly implicated in inflammatory skin diseases, namely in allergic contact dermatitis. In this work, we investigated the effect of dexamethasone on NO production induced by the epidermal cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) in a mouse fetal skin dendritic cell line. METHODS: NO production was assessed by the method of Griess. Expression of the inducible isoform of nitric oxide synthase (iNOS) protein was evaluated by western blot analysis and immunofluorescence microscopy. Western blot analysis was also performed to evaluate cytosolic IkappaB-alpha (IkappaB-alpha) protein levels. The electrophoretic mobility shift assay was used to evaluate the activation or inhibition of nuclear factor kappa B (NF-kappaB). RESULTS: GM-CSF induced iNOS expression and NO production, and activated the transcription factor NF-kappaB. Dexamethasone inhibited, in a dose-dependent manner, NO production induced by GM-CSF. Addition of dexamethasone to the culture, 30 min before GM-CSF stimulation, significantly inhibited the cellular expression of iNOS. Dexamethasone also inhibited GM-CSF-induced NF-kappaB activation by preventing a significant decrease on the IkappaB-alpha protein levels, thus blocking NF-kappaB migration to the nucleus. CONCLUSIONS: The corticosteroid dexamethasone inhibits GM-CSF-induced NF-kappaB activation, iNOS protein expression and NO production. These results suggest that dexamethasone is a potent inhibitor of intracellular events that are involved on NO synthesis, in skin dendritic cells

Release of IL-1β via IL-1β-Converting Enzyme in a Skin Dendritic Cell Line Exposed to 2,4-Dinitrofluorobenzene

We used a mouse fetal skin dendritic cell line (FSDC) to study the effect of the strong allergen 2,4-dinitrofluorobenzene (DNFB) on interleukin (IL)-1β release and IL-1β receptor immunoreactivity. Stimulation with DNFB (30 minutes) increased IL-1β release without changing the mRNA levels of the protein. Furthermore, DNFB increased transiently the interleukin-1β-converting enzyme (ICE) activity, as measured with its fluorogenic substrate Z-Tyr-Val-Ala-Asp-AFC. The ICE inhibitor Z-YVAD-FMK prevented the release of IL-1β evoked by DNFB. Incubation of the cells with DNFB (30 minutes) strongly increased IL-1β receptor immunoreactivity. The rapid effect of DNFB on the release of mature IL-1β, without inducing an increase of IL-1β mRNA in FSDC, suggests a posttranslational modification of pro-IL-1β by ICE activity

Extraction of available and labile fractions of mercury from contaminated soils : the role of operational parameters

One of the recognized challenges in chemical extraction of mercury from soil is the diversity of procedures that are currently available in literature and that differ in terms of the extractant solution used, soil:extractant ratio and duration of extraction. Therefore, this study focused on establishing the role of operational parameters for extraction of the available and labile fractions of mercury from soils, considering different soil:extractant ratios and the kinetics of extraction. The suitability of 1.0 mol L− 1 ammonium acetate at pH 7 and 0.1 mol L− 1 HCl as extractants for the available fraction and the extraction of the labile fraction using 0.5 mol L− 1 hydrochloric acid was investigated. No statistical differences were found between ammonium acetate and 0.1 mol L− 1 HCl; therefore both extractants can be used for estimating the available fraction. It was also observed that a soil:extractant ratio of 1.5 g of soil to 100 mL of extractant favors mercury extraction. For the available fraction an extraction of 30 min seems enough, as no further significant change was observed in the quantity of mercury extracted thereafter. For the labile fraction increase the extraction duration to at least 24 h is recommended. The data was fitted into kinetic models, and it was observed that the two first-order reactions and the diffusion models help to understand the behavior of mercury extraction from soil, clearly showing that in all cases the rate of mercury extraction was faster in the first 10 h and declined after that period. The characteristics of the soil influenced the extraction of mercury, and it was verified that pH and particle size of the soil influenced the mercury extraction process, as results suggested that an acidic soil might have a reduced ability to strongly retain metals and soils with higher porosity showed lower rates of mercury extraction