Effects of alkaline and acid solutions on glass/epoxy composites

Composite structures can be exposed to a range of corrosive environments during their in-service life, which causes degradation in terms of material properties. The effect of alkaline and acid solutions on the GRP mechanical properties can be found in open literature, but the studies presented are not sufficient to establish a full knowledge of this subject. In this paper the flexural properties and the impact strength of a glass fibre/epoxy composite after immersion in hydrochloric acid (HCl) and sodium hydroxide (NaOH) were analysed. Independently of the solution, the flexural strength and the flexural modulus decrease with the exposure time. However, alkaline solution promotes higher decrease of the flexural properties than the acid solution. The same tendency was observed for impact strength

Measuring transverse relaxation in highly paramagnetic systems

The enhancement of nuclear relaxation rates due to the interaction with a paramagnetic center (known as Paramagnetic Relaxation Enhancement) is a powerful source of structural and dynamics information, widely used in structural biology. However, many signals affected by the hyperfine interaction relax faster than the evolution periods of common NMR experiments and therefore they are broadened beyond detection. This gives rise to a so-called blind sphere around the paramagnetic center, which is a major limitation in the use of PREs. Reducing the blind sphere is extremely important in paramagnetic metalloproteins. The identification, characterization, and proper structural restraining of the first coordination sphere of the metal ion(s) and its immediate neighboring regions is key to understand their biological function. The novel HSQC scheme we propose here, that we termed R2-weighted, HSQC-AP, achieves this aim by detecting signals that escaped detection in a conventional HSQC experiment and provides fully reliable R2 values in the range of 1H R2 rates ca. 50–400 s−1. Independently on the type of paramagnetic center and on the size of the molecule, this experiment decreases the radius of the blind sphere and increases the number of detectable PREs. Here, we report the validation of this approach for the case of PioC, a small protein containing a high potential 4Fe-4S cluster in the reduced [Fe4S4]2+ form. The blind sphere was contracted to a minimal extent, enabling the measurement of R2 rates for the cluster coordinating residues.publishersversionpublishe

1H, 13C and 15N assignment of the paramagnetic high potential iron–sulfur protein (HiPIP) PioC from Rhodopseudomonas palustris TIE-1

High potential iron–sulfur proteins (HiPIPs) are a class of small proteins (50–100 aa residues), containing a 4Fe–4S iron–sulfur cluster. The 4Fe–4S cluster shuttles between the oxidation states [Fe4S4]3+/2+, with a positive redox potential in the range (500–50 mV) throughout the different known HiPIPs. Both oxidation states are paramagnetic at room temperature. HiPIPs are electron transfer proteins, isolated from photosynthetic bacteria and usually provide electrons to the photosynthetic reaction-center. PioC, the HIPIP isolated from Rhodopseudomonas palustris TIE-1, is the smallest among all known HiPIPs. Despite their small dimensions, an extensive NMR assignment is only available for two of them, because paramagnetism prevents the straightforward assignment of all resonances. We report here the complete NMR assignment of 1H, 13C and 15N signals for the reduced [Fe4S4]2+ state of the protein. A set of double and triple resonance experiments performed with standardized parameters/datasets provided the assignment of about 72% of the residues. The almost complete resonance assignment (99.5% of backbone and ca. 90% of side chain resonances) was achieved by combining the above information with those obtained using a second set of NMR experiments, in which acquisition and processing parameters, as well as pulse sequences design, were optimized to account for the peculiar features of this paramagnetic protein.publishersversionpublishe

A non-systematic approach

Funding Information: This work benefited from access to CERM/CIRMMP, the Instruct-ERIC Italy centre. Financial support was provided by European EC Horizon 2020 TIMB3 (Project 810856) Instruct-ERIC (PID 4509). This article is based upon work from COST Action CA15133, supported by COST (European Cooperation in Science and Technology) . Fondazione Ente Cassa di Risparmio di Firenze ( CRF 2016 0985 ) is acknowledged for providing fellowship to MI. This work was funded by national funds through FCT– Fundação para a Ciência e a Tecnologia , I.P., Project MOSTMICRO-ITQB with refs UIDB/04612/2020 and UIDP/04612/2020, and Fundação para a Ciência e a Tecnologia (FCT) Portugal is acknowledged for Grant PD/BD/135187/2017 to IBT. Funding Information: This work benefited from access to CERM/CIRMMP, the Instruct-ERIC Italy centre. Financial support was provided by European EC Horizon 2020 TIMB3 (Project 810856) Instruct-ERIC (PID 4509). This article is based upon work from COST Action CA15133, supported by COST (European Cooperation in Science and Technology). Fondazione Ente Cassa di Risparmio di Firenze (CRF 2016 0985) is acknowledged for providing fellowship to MI. This work was funded by national funds through FCT? Funda??o para a Ci?ncia e a Tecnologia, I.P. Project MOSTMICRO-ITQB with refs UIDB/04612/2020 and UIDP/04612/2020, and Funda??o para a Ci?ncia e a Tecnologia (FCT) Portugal is acknowledged for Grant PD/BD/135187/2017 to IBT. Publisher Copyright: © 2020 The Author(s) Copyright: Copyright 2020 Elsevier B.V., All rights reserved.The complete assignment of 1H, 13C and 15N protein signals, which is a straightforward task for diamagnetic proteins provided they are folded, soluble and with a molecular mass below 30,000 Da, often becomes an intractable problem in the presence of a paramagnetic center. Indeed, the hyperfine interaction quenches signal intensity; this prevents the detection of scalar and dipolar connectivities and the sequential assignment of protein regions close to the metal ion(s). However, many experiments can be optimized and novel experiments can be designed to circumvent the problem and to revive coherences invisible in standard experiments. The small HiPIP protein PioC provides an interesting case to address this issue: the prosthetic group is a [Fe4S4]2+ cluster that is bound to the 54 amino acids protein via four cysteine residues. The four cluster-bound cysteine residues adopt different binding conformations and therefore each cysteine is affected by paramagnetic relaxation to different extent. A network of tailored experiments succeeded to obtain the complete resonance assignment of cluster bound residues.publishersversionpublishe

Tectonic insights of the southwest Amazon Craton from geophysical, geochemical and mineralogical data of Figueira Branca mafic-ultramafic suite, Brazil

This work was done with the support of the CNPq, National Council for Technological and Scientific Development – Brazil [grant numbers 443355/2014-2, 200473/2015-8, 141587/2013-0]; Peter A. Cawood acknowledges support from the Australian Research Council [grant number FL160100168].The Figueira Branca Suite is a layered mafic-ultramafic complex in the Jauru Terrane, southwest Amazon Craton. New lithological, geochemical, gamma-ray and potential field data, integrated with geological, isotope and paleomagnetic data are used to characterize this pulse of Mesoproterozoic extension-related magmatism. The Figueira Branca Suite formed through juvenile magma emplacement into the crust at 1425 Ma, coeval with the later stages of the Santa Helena Orogen. Gabbros and peridotite-gabbros display increasing enrichment of LREE, interpreted as evidence of progressive fractionation of the magma. Magnetic and gamma-ray data delimit the extent of magmatism within the suite to four bodies to the north of Indiavaí city. Modelling gravity and magnetic field data indicate that the anomalous sources are close to the surface or outcropping. These intrusions trend northwest over 8 km, with significant remanent magnetization that is consistent with published direction obtained through paleomagnetic data. The emplacement, mineralogy and geochemical signature point towards a back-arc extension tectonic framework in the later stages of the Santa Helena Orogen.PostprintPeer reviewe

Ageing profiling of craft beers: a sensorial and chemical overview

One of the main differences between craft and commercial beers is the presence of active yeast in the bottle, which can have high impact on beer stability during shelflife. For this reason, sensory and chemical beer profiling during storage is of upmost importance when focusing quality control. This study investigated the changes that occur during the storage/ageing of four different craft beers and two commercial beers, which were used for comparison. Sensory analysis of capped and corked beers was performed overtime accompanied by sampling for minor volatiles analysis. Craft beers showed an aromatic profile more intense than the commercial beers and kept the profile similar after six months, as well as the commercial beers. Fruity, floral and caramel were among the main descriptors found for the beers studied, and maintained their intensity during the analysis time. Minor compounds analysis was coherent with the aromatic profiles obtained, as well as those portrayed in the literature, however most of the main ageing markers reported were not found in the beers studied. Among the minor volatiles studied esters concentration varied differently depending on beer type and alcohols, fatty acids, carbonyl compounds and pyrazines concentrations increased for all beers. However, variations on minor volatiles composition had low impact on sensorial perception. The results allowed to conclude that the craft beers maintained the sensory quality as a commercial beer, over a six month period, with the benefit of having more intense flavors and aromas when compared to the commercial beers studied.info:eu-repo/semantics/publishedVersio

13C detected experiments illuminate the vicinity of the metal center

Funding Information: The support of the CERM/CIRMMP center of Instruct-ERIC is gratefully acknowledged. This work was supported in part by the project “Potentiating the Italian Capacity for Structural Biology Services in Instruct-ERIC" (ITACA.SB, Project no. IR0000009) within the call MUR 3264/2021 PNRR M4/C2/L3.1.1, funded by the European Union—Next Generation EU. LQ is a PhD student under the Tuscany Health Ecosystem-ECS_00000017 (CUP B83C22003920001), spoke 7, funded by the European Union—Next Generation EU. This work was funded by national funds through FCT–Fundação para a Ciência e a Tecnologia, I.P. (FCT), Project MOSTMICRO-ITQB with refs UIDB/04612/2020 and UIDP/04612/2020, and LS4FUTURE Associated Laboratory (LA/P/0087/2020). Funding Information: Open access funding provided by Università degli Studi di Firenze within the CRUI-CARE Agreement. Publisher Copyright: © 2023, The Author(s).The robustness of NMR coherence transfer in proximity of a paramagnetic center depends on the relaxation properties of the nuclei involved. In the case of Iron-Sulfur Proteins, different pulse schemes or different parameter sets often provide complementary results. Tailored versions of HCACO and CACO experiments significantly increase the number of observed Cα/C’ connectivities in highly paramagnetic systems, by recovering many resonances that were lost due to paramagnetic relaxation. Optimized 13C direct detected experiments can significantly extend the available assignments, improving the overall knowledge of these systems. The different relaxation properties of Cα and C’ nuclei are exploited in CACO vs COCA experiments and the complementarity of the two experiments is used to obtain structural information. The two [Fe2S2]+ clusters containing NEET protein CISD3 and the one [Fe4S4]2+ cluster containing HiPIP protein PioC have been taken as model systems. We show that tailored experiments contribute to decrease the blind sphere around the cluster, to extend resonance assignment of cluster bound cysteine residues and to retrieve details on the topology of the iron-bound ligand residues.publishersversionpublishe

New p-i-n Si : H imager configuration for spatial resolution improvement

Amorphous glass/ZnO-Al/p(a-Si:H)/i(a-Si:H)/n(a-Si1-xCx:H)/Al imagers with different n-layer resistivities were produced by plasma enhanced chemical vapour deposition technique (PE-CVD). An image is projected onto the sensing element and leads to spatially confined depletion regions that can be readout by scanning the photodiode with a low-power modulated laser beam. The essence of the scheme is the analog readout, and the absence of semiconductor arrays or electrode potential manipulations to transfer the information coming from the transducer. The influence of the intensity of the optical image projected onto the sensor surface is correlated with the sensor output characteristics (sensitivity, linearity blooming, resolution and signal-to-noise ratio) are analysed for different material compositions (0.5 < x < 1). The results show that the responsivity and the spatial resolution are limited by the conductivity of the doped layers. An enhancement of one order of magnitude in the image intensity signal and on the spatial resolution are achieved at 0.2 mW cm(-2) light flux by decreasing the n-layer conductivity by the same amount. A physical model supported by electrical simulation gives insight into the image-sensing technique used

Heritability of cortisol response to confinement stress in European sea bass dicentrarchus labrax

Background: In fish, the most studied production traits in terms of heritability are body weight or growth, stress or disease resistance, while heritability of cortisol levels, widely used as a measure of response to stress, is less studied. In this study, we have estimated heritabilities of two growth traits (body weight and length) and of cortisol response to confinement stress in the European sea bass. Findings: The F1 progeny analysed (n = 922) belonged to a small effective breeding population with contributions from an unbalanced family structure of just 10 males and 2 females. Heritability values ranged from 0.54 (+/- 0.21) for body weight to 0.65 (+/- 0.22) for standard body length and were low for cortisol response i.e. 0.08 (+/- 0.06). Genetic correlations were positive (0.94) between standard body length and body weight and negative between cortisol and body weight and between cortisol and standard body length (-0.60 and -0.55, respectively). Conclusion: This study confirms that in European sea bass, heritability of growth-related traits is high and that selection on such traits has potential. However, heritability of cortisol response to stress is low in European sea bass and since it is known to vary greatly among species, further studies are necessary to understand the reasons for these differences