Exposure to silver and titanium dioxide nanoparticles at supra-environmental concentrations decreased sperm motility and affected spermatozoa subpopulations in gilthead seabream, Sparus aurata

Marine pollution by nanoparticles (NPs) can be reprotoxic for fish and disturb successful reproduction of wild populations. In gilthead seabream (Sparus aurata), a mild effect on sperm motility was observed after exposure to high concentrations of silver NPs. Considering the great heterogeneity traits within a sperm sample, it is possible that NPs affect spermatozoa accordingly, modulating subpopulation profile. Thus, this work aimed to analyse NP effects in sperm motility in general and considering spermatozoa population structure, using a subpopulation approach. Seabream sperm samples from mature males were exposed for 1 h to increasing concentrations of titanium dioxide (1, 10, 100, 1000 and 10,000 & mu;g L-1) and silver (0.25, 25 and 250 & mu;g L-1) NPs, including Ag NP and Ag+, dissolved in a non-activating medium (0.9 % NaCl). Concentrations chosen include realistic (10-100 and 0.25 & mu;g L-1, respectively, for TiO2 and Ag) and supra-environmental values. The mean particle diameter was determined as 19.34 & PLUSMN; 6.72 and 21.50 & PLUSMN; 8.27 nm in the stock suspension, respectively, for titanium dioxide and silver. After the ex vivo exposure, sperm motility parameters were determined using computer-assisted sperm analysis, and sperm subpopulations were later identified using a two-step cluster analysis. Results revealed a significant reduction in total motility after exposure to the 2 highest concentrations of titanium dioxide NPs, while curvilinear and straight-line velocities were not altered. Exposure to silver NPs (Ag NP and Ag+) lowered significantly total and progressive motilities at all concentrations, while curvilinear and straight-line velocities were significantly lower only at the highest concentration. Sperm subpopulations were also affected by the exposure to both titanium dioxide and silver NPs. In both cases, the highest levels of NPs triggered a decrease in the percentage of fast sperm subpopulations (38.2% in TiO2 1000 & mu;g L-1, 34.8.% in Ag NP 250 & mu;g L-1, and 45.0% in Ag+ 250 & mu;g L-1 vs 53.4% in the control), while an increase on slow sperm subpopulations. A reprotoxic effect was proven for both NPs, but only at supra-environmental concentrations.Operational Program Competitiveness and Internationalization (POCI) POCI-01-0145-FEDER-30908, Fundacao para a Ciencia e a Tecnologia (FCT) SFRH/2020/05105/BD, LA/P/0101/2020, LA/P/0094/2020info:eu-repo/semantics/publishedVersio

Medium supplementation with magnesium prevented the induction of dormancy in biofilms of clinical and commensal isolates of Staphylococcus epidermidis

Staphylococcus epidermidis is a commensal bacterium that colonizes the skin and mucous membranes, being the most prevalent staphylococcal species found in humans. However, S. epidermidis has the ability of colonize indwelling medical devices establishing biofilms, which makes this bacteria a common cause of bacteraemia particularly in immunocompromised individuals and neonates [1][2]. The presence of high amounts of dormant bacteria (viable but non-culturable cells, VBNC) is a hallmark of biofilms, making them more tolerant to antimicrobials and elusive to the host immune response [3]. Glucose (G) is commonly used in vitro to induce a biofilm mode of growth in S. epidermidis cultures [4] due to the medium acidification derived from carbon metabolism [5]. Previous studies in our laboratory demonstrated that the accumulation of VBNC bacteria inside S. epidermidis biofilms could be prevented by supplementation of the medium with magnesium (Mg) (unpublished data). In the present work, a flow cytometric live/dead staining [6], in combination with the spreadplate method, were used to evaluate the effect of magnesium in preventing dormancy on glucose excess-grown biofilms in 53 strains of international clinical, Portuguese clinical, and Portuguese commensal isolates of S. epidermidis. Culture supplementation with Mg2+ prevented the accumulation of death bacteria inside the biofilms in all the groups of strains tested, being the proportion of live bacteria (SYBR+PI-) significantly increased by Portuguese clinical isolates. The quantification of colony forming units (CFUs) revealed that Mg hampered the induction of dormancy in all the groups of strains studied (International clinical G: 3,60,8×107 vs. G+Mg: 2,60,5×108, Portuguese clinical 6,82,0×107 vs. 4,31,4×108, Portuguese commensal 7,21,5×107 vs. 2,60,4×108 CFUs/mL). These results confirmed that dormancy modulation is widespread in different S. epidermidis isolates obtained from clinical and commensal sources, suggesting that this is indeed an important mechanism of S. epidermidis biofilm physiology

A IMPORTÂNCIA DA LEITURA NO ENSINO FUNDAMENTAL - UMA PERSPECTIVA INTERDISCIPLINAR

A evolução do ser humano e o avanço da civilização dependeram principalmente da evolução dos meios de receber, comunicar, registrar os conhecimentos e particularmente do desenvolvimento da leitura e da escrita. O homem é um animal comunicativo e essa comunicação se constitui numa de suas atividades essenciais. Este artigo descreve a importância da leitura e sua perspectiva Interdisciplinar, assim como seus efeitos no desenvolvimento do ser humano, objetivando sobretudo uma. vida melhor dentro da sociedade na qual está inserido

Magnetic/plasmonic MnFe2O4/Au nanoparticles covered with lipid bilayers for applications in thermotherapy

In this work, three different types of magnetic/plasmonic nanoparticles were prepared: core-shell nanoparticles with a manganese ferrite core and a gold shell; plasmonic gold nanoparticles decorated with magnetic nanoparticles of manganese ferrite; and magnetic nanoparticles of manganese ferrite decorated with plasmonic gold nanoparticles. The structural, spectroscopic and magnetic properties of these nanoparticles were evaluated. In order to further develop applications in cancer therapy, the prepared mixed nanoparticles were covered with a lipid bilayer. The local heating capability of these nanosystems was tested through the quenching of rhodamine fluorescence incorporated in the lipid layer.Financial support by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. A.R.O Rodrigues thanks the FCT for SFRH/BD/90949/2012 PhD grant and funding to MAP-Fis Doctoral Program.info:eu-repo/semantics/publishedVersio

Polymorphism and Superconductivity in Bilayer Molecular Metals (CNB-EDT-TTF)4I3

Electrocrystallization from solutions of the dissymmetrical ET derivative cyanobenzene-ethylenedithio-tetrathiafulvalene (CNB-EDT-TTF) in the presence of triiodide I3 − affords two different polymorphs (β″ and κ) with the composition (CNB-EDT-TTF)4I3, both with a bilayer structure of the donors. These polymorphs differ in the packing patterns (β″- and κ-type) of the donor molecules in each layer, in both cases with bifurcated C−N···H interactions effectively coupling head-to-head donor molecules between layer pairs. Two β″ polymorphs can be obtained with different degrees of anionic ordering. In one disordered phase, β″d, with a smaller unit cell, the triiodide anions are disordered over two possible positions in a channel between the donor bilayers, while in the ordered phase, β″o, the triiodide anions occupy only one of those positions in this channel, leading to the doubling of the unit cell in the layer plane. These results for β″ phases contrast with the κ polymorph previously reported, for which weaker disorder of the triiodide anions, over two possible orientations with 94 and 6% occupation factors, was observed. While the β″ polymorphs remains metallic down to 1.5 K with a ρ300K/ρ4K resistivity ratio of 250, the κ polymorph presents a much smaller resistivity ratio in the range of 4−10 and superconductivity with an onset temperature of 3.5 K.This work was partially supported in Portugal by FCT under Contracts UID/Multi/04349/2013 and RECI/QEQ-QIN/ 0189/2012 and grants to S.O. (SFRH/BD/72722/2010) and S.R. (SFRH/BPD/113344/2015). Work in Bellaterra was supported by MINECO-Spain (Grant FIS2015-64886-C5-4- P) and Generalitat de Catalunya (2014SGR301). E.C. acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2015-0496.Peer reviewe

Incorporation of neuroprotective compounds of Hypericum perforatum in polymeric nanoparticles

Hypericum perforatum extracts have been used for their antidepressive effects. Recently, a selected fraction (HP) isolated from these extracts and containing compounds like quercetin and biapigenin proved to be neuroprotective [1,2].info:eu-repo/semantics/publishedVersio

A hybrid cementitious based-G/CFRP sandwich panel: concept, design and initial outcomes

Nowadays, the advantages of using fibre-reinforced polymers (FRP) in Civil Engineering structures are very well-known. In comparison to other materials, the FRPs show high strength-to-weight and stiffness-to-weight ratios, as well as high corrosion resistance [1]. Moreover, they can be easily moulded into complex shapes during the manufacturing process. Due to the slenderness of the cross section components and systems [2], and their significant initial cost [3], the FRPs are typically used along with other materials in composite structural elements. In the recent years, the FRPs have been increasingly used in composite sandwich panels designed for the building and housing industry [4]. However, in terms of flooring solutions, the sandwich panels still reveal some limitations for the most typical values of spans and loads in buildings [5]. In order to overcome the aforementioned drawbacks, the EasyFloor project was launched to develop enhanced composite sandwich panels for rehabilitation of floors in buildings. One of the important innovations included in the project relies on the use of both glass and carbon fibre roving (G/CFRP). This hybrid solution aims at improving significantly both the strength and stiffness. Furthermore, the top face of the panel is made of steel fibre reinforced self-compacting micro concrete (SFRSCMC), instead of the usual FRP compressive face, aiming to overcome face wrinkling issues. Additionally, this solution can provide higher ductility, fire endurance and impact resistance [6]. Furthermore, polycianurate (PIR) closed-cell foam is used as core material of the panel. Proper adhesion between G/CFRP and SFRSCMC is developed in order to obtain the full bending capacity of the composite solution. Finally, the FRP component is produced by pultrusion, taking all the advantages of this manufacturing process. The final proposal for the hybrid sandwich panel was obtained through the use of genetic algorithms in the design, which consisted in optimizing the geometric and the mechanical properties of the panel, taking into account the following features: (i) structural and energy efficiency; (ii) durability, versatility of use, ease of handling, quick assembly and production; (iii) low maintenance needs and aesthetics. The present work describes the design solution that resulted from the optimization procedure and subsequently presents initial experimental results regarding the mechanical characterization of the different materials, as well as the FRP/SFRSCMC interface. The experimental program comprised: (i) tensile and flexural tests on both the bottom and external ribs of the C/GFRP laminate skins; (ii) tensile, compressive and direct shear tests on both foam core materials (PIR); (iii) compressive and flexural tests on the SFRSCMC top face, and; (iv) pull-off tests for the characterization of the connection between the SFRSCMC and FRP using different types of adhesives.This work is part of the research project “EasyFloor – Development of composite sandwich panels for rehabilitation of floor buildings”, involving the company ALTO – Perfis Pultrudidos, Lda., CERis/Instituto Superior Técnico and ISISE/University of Minho, supported by FEDER funds through the Operational Program for Operational Program for Competitiveness and Internationalization (POCI) and the Portuguese National Innovation Agency (ANI) - project no. 3480 (POCI-01-0247-FEDER-003480). The authors would like to thanks the following companies for suppling the adhesives: KERAKOLL, MAPEI and SIKADUR.info:eu-repo/semantics/publishedVersio