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Nanotubes of self-assembled dipeptides exemplified by diphenylalanine (FF) demonstrate a wide range of useful functional properties, such as high Young's moduli, strong photoluminescence, remarkable piezoelectricity and pyroelectricity, optical waveguiding, etc., and became the object of intensive research due to their ability to combine electronic and biological functions in the same material. Two types of nanoconfined water molecules (bound water directly interacting with the peptide backbone and free water located inside nanochannels) are known to play a key role in the self-assembly of FF. Bound water provides its structural integrity, whereas movable free water influences its functional response. However, the intrinsic mechanism of water motion in FF nanotubes remained elusive. In this work, we study the sorption properties of FF nanotubes directly considering them as a microporous material and analyze the free water self-diffusion at different temperatures. We found a change in the regime of free water diffusion, which is attributed to water cluster size in the nanochannels. Small clusters of less than five molecules per unit cell exhibit ballistic diffusion, whereas, for larger clusters, Fickian diffusion occurs. External conditions of around 40% relative humidity at 30 °C enable the formation of such large clusters, for which the diffusion coefficient reaches 1.3 × 10

[Gd(H4nmp)(H2O)2]Cl·2H2O (1) converts into [Gd2(H3nmp)2]·xH2O (2) (x = 1 to 4) with a notable increase in proton conductivity., [Gd(H4nmp)(H2O)2]Cl·2H2O (1) converts into [Gd2(H3nmp)2]·xH2O (2) (x = 1 to 4) with a notable increase in proton conductivity. 1 is a charged layered material counter balanced by chloride ions, with proton conductivity values of 1.23 × 10–5 S cm–1 at 98% relative humidity (RH) and 40 °C. At 98% RH and 94 °C the observed conductivity is 0.51 S cm–1, being to date one of the highest values ever reported for a proton-conducting coordination polymer. This increase is observed during a structural transformation into 2 that occurs at high temperature and RH. While this remarkable conductivity is observed only after transformation and by maintaining high humidity conditions, as-synthesized 2 also shows a conductivity value of 3.79 × 10–2 S cm–1 at 94 °C and 98% RH, still ranked as one of the highest reported values. Moreover, it is shown that the key factor for high proton conduction is the unusual dynamic structural transformation with water insertion and release of chloride ions.

Simple Summary Activation of immune cells is bioenergetically expensive, requiring precise control of cellular metabolism. This applies also to innate immune cells. The current study shows that the immunostimulants, Astragalus, Hyaluronic acid, Imiquimod, and Poly I:C can modulate the expression of genes involved in the innate antiviral immune, as well as genes associated with metabolism, in the early life stages of Atlantic salmon. Abstract Disease resistance of fish larvae may be improved by bath treatment in water containing immunostimulants. Pattern recognition receptors, such as TLR3, TLR7, and MDA5, work as an “early warning” to induce intracellular signaling and facilitate an antiviral response. A single bath of newly hatched larvae, with Astragalus, upregulated the expression of IFNα, IFNc, ISG15, MDA5, PKR, STAT1, TLR3, and TLR7 immune genes, on day 4 post treatment. Similar patterns were observed for Hyaluronic acid and Poly I:C. Increased expression was observed for ISG15, MDA5, MX, STAT1, TLR3, TLR7, and RSAD2, on day 9 for Imiquimod. Metabolic gene expression was stimulated on day 1 after immunostimulant bath in ULK1, MYC, SLC2A1, HIF1A, MTOR, and SIX1, in Astragalus, Hyaluronic acid, and Imiquimod. Expression of NOS2 in Poly I:C was an average fourfold above that of control at the same timepoint. Throughout the remaining sampling days (2, 4, 9, 16, 32, and 45 days post immunostimulant bath), NOS2 and IL1B were consistently overexpressed. In conclusion, the immunostimulants induced antiviral gene responses, indicating that a single bath at an early life stage could enable a more robust antiviral defense in fish. Additionally, it was demonstrated, based on gene expression data, that cell metabolism was perturbed, where several metabolic genes were co-regulated with innate antiviral genes.

The development of efficient electrocatalysts for slow reaction of the oxygen evolution reaction (OER) is fundamental for viability of the electrochemical water splitting technologies. Here we report for the first time the synthesis of NiO/carbon hollow fibres (NiO-HF) by the Solution Blow Spinning (SBS) technique, and a study of their catalytic activity towards the OER in alkaline medium. The hollow fibres were obtained with ca. 300 nm in diameter consisting of agglomerated NiO nanoparticles with an average size of 50 nm which is close to the tubular wall thickness. The formation mechanism of the hollow structure was discussed. It was revealed that the carbon from polyenic branch of polyvinylpyrrolidone (PVP) resists the firing treatment and acts as an agglomerating agent, thus ensuring a conductive and percolating path between NiO nanoparticles along the fibres. A battery of electrochemical tests of NiO-HF supported by commercial Ni foam reveals excellent electrochemical activity for OER in 1 M KOH, in comparison with reference NiO nanoparticles (NiO-NP, diameter ca. 23 nm). NiO-HF attains an overpotential of 340 mV vs. RHE at a current density of 10 mA cm−2, which is amongst the lowest values reported in the literature for undoped NiO. Chronopotentiometry reveals stable NiO-HF electrodes over 15 h under an electrolysis current of 25 mA cm−2. Microscopic analysis shows that the fibrillar morphology is completely preserved after the electrolysis test. The remarkable performance of the NiO-HF catalyst is ascribed to the enhanced electronic conductivity resulting from the interpenetrating NiO-HF/carbon microstructure.

Hydrogen is a clean energy carrier and fuel cells (FCs) are an efficient conversion technology, and thus have become mainstream research topics that could contribute to sustainable and clean energy supply in modern society. Among the various hydrogen FC types that convert chemical energy into electrical energy via redox reactions, polymer electrolyte fuel cells (PEFCs) are the most studied technology due to their vast range of applications both mobile and stationary. The use of bio-based materials as substrates for the manufacture of the key constituent components of FCs, to minimize the impact of their production, although in its infancy, is growing exponentially as part of the general concern for sustainability. In fact, natural polymers such as cellulose (i.e. the most abundant biopolymer), and in particular its nanoscale forms, viz. cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and bacterial nanocellulose (BNC), are appropriate materials to engineer the key components of PEFCs, namely the ion-exchange membrane and the catalyst layer (anode and cathode). Despite the intense R&D activity, little has been reviewed about the potential application of these three forms of cellulose with at least one dimension in the nanoscale in the field of FCs. Hence, the overarching goal of this review is to concentrate on the most recent efforts in the domain of bio-based PEFC components, namely the ion-exchange membrane and the electrodes, by targeting the use of nanocellulose as a renewable and easily foldable or stackable nanomaterial. The application of these nanocellulose-based components in microbial fuel cells (MFCs) is also covered.

Porous robust materials are typically the primary selection of several industrial processes. Many of these compounds are, however, not robust enough to be used as multifunctional materials. This is typically the case of Metal-Organic Frameworks (MOFs) which rarely combine several different excellent functionalities into the same material. In this report we describe the simple acid-base postsynthetic modification of isotypical porous rare-earth-phosphonate MOFs into a truly multifunctional system, maintaining the original porosity features: [Ln(H3pptd)]·xSolvent [where Ln3+ = Y3+ (1) and (Y0.95Eu0.05)3+ (1_Eu)] are converted into [K3Ln(pptd)]·zSolvent [where Ln3+ = Y3+ (1K) and (Y0.95Eu0.05)3+ (1K_Eu)] by immersing the powder of 1 and 1_Eu into an ethanolic solution of KOH for 48 h. The K+-exchanged Eu3+-based material exhibits a considerable boost in CO2 adsorption, capable of being reused for several consecutive cycles. It can further separate C2H2 from CO2 from a complex ternary gas mixture composed of CH4, CO2, and C2H2. This high adsorption selectivity is, additionally, observed for other gaseous mixtures, such as C3H6 and C3H8, with all these results being supported by detailed theoretical calculations. The incorporation of K+ ions notably increases the electrical conductivity by 4 orders of magnitude in high relative humidity conditions. The conductivity is assumed to be predominantly protonic in nature, rendering this material as one of the best conducting MOFs reported to date. published

The utilization of biobased materials for the fabrication of naturally derived ion-exchange membranes is breezing a path to sustainable separators for polymer electrolyte fuel cells (PEFCs). In this investigation, bacterial nanocellulose (BNC, a bacterial polysaccharide) and lignosulfonates (LS, a by-product of the sulfite pulping process), were blended by diffusion of an aqueous solution of the lignin derivative and of the natural-based cross-linker tannic acid into the wet BNC nanofibrous three-dimensional structure, to produce fully biobased ion-exchange membranes. These freestanding separators exhibited good thermal-oxidative stability of up to about 200 &deg, C, in both inert and oxidative atmospheres (N2 and O2, respectively), high mechanical properties with a maximum Young&rsquo, s modulus of around 8.2 GPa, as well as good moisture-uptake capacity with a maximum value of ca. 78% after 48 h for the membrane with the higher LS content. Moreover, the combination of the conducting LS with the mechanically robust BNC conveyed ionic conductivity to the membranes, namely a maximum of 23 mS cm&minus, 1 at 94 &deg, C and 98% relative humidity (RH) (in-plane configuration), that increased with increasing RH. Hence, these robust water-mediated ion conductors represent an environmentally friendly alternative to the conventional ion-exchange membranes for application in PEFCs.

Water absorption capacity is a key characteristic of cellulosic pulps used for different commodities. This property is influenced by the affinity of the pulp fiber surface with water, chemical composition of the pulp, morphology, and organization of fibers in the network. In this study, surface properties of six industrial Eucalyptus bleached kraft pulps (fluff pulps) dry-defiberized in a Hammermill, which were obtained by wood pulping and pulp bleaching under different production conditions, were studied while employing dynamic water vapor sorption and contact angles measurements. The absorption properties of air-laid pulp pads were analyzed following the absorbency testing procedure and the relationship between these properties and pulp&rsquo, s chemical composition and fiber network structure were assessed by multivariate analysis. The results showed that the accessibility of the fiber surface is related to the reduction of the contact angles, but, at the same time, to the longer absorption time and less absorption capacity of the fiber network. Therefore, the absorption properties of the pulps are not necessarily directly related to their surface properties. Indeed, absorptivity is related to the surface chemical composition, fiber morphology, and fiber network structure. Thus, surface carboxylic groups promote total water uptake, resulting in better absorption capacity. Greater fiber coarseness and deformations (curl and kink) provide a less wettable surface, but a more porous network with higher specific volume, resulting in more absorbent air-laid formulations.

Herein, we present a simple and inexpensive method for the immobilization of Metal&ndash, Organic Framework (MOF) particles in the form of pellets and membranes. This processing procedure is possible using polymethacrylate polymer (PMMA) as a binding or coating agent, improving stability and significantly increasing the water repellency. HKUST and MMOF-74 (M = Mg2+, Zn2+, Co2+ or Ni2+) are stable with the processing and high loadings of MOF materials into the processed pellet or membranes. These methods can provide the know-how for the immobilization of MOFs for, for example, application in air purification and the removal of toxic compounds and are well-suited for deployment in air purification devices

Novel electrolytes composed of chondroitin sulfate A (CSA) and citric acid (CA) have been prepared using a clean, safe, and fast route. These electrolytes exhibit different physical-chemical properties, depending on the amount of CA. For X > 82.3%, where X is the mass ratio, in %, of CA/(CA + CSA), whitish polycrystalline powders result. Lower amounts of CA leads to the production of translucent, amorphous films, sticky for X = 75.6 and 82.0, brittle for X < 43.6 and crack-free, self-standing for 43.6 < X < 75.6%. The results obtained provide evidence that, at low pH, strong hydrogen bonding interactions take place between the anionic sulfonic and carboxylic groups of CSA and CA. CA exerts a key role, acting as a cross-linker and proton source, while simultaneously influencing sample morphology. At room temperature the highest ionic conductivity is achieved at X = 60.8%. A significant enhancement of the ionic conductivity of this sample occurs with the increase of relative humidity (RH) (from 3.1 × 10−7 to 3.7 × 10−2 S cm−1 30% for RH = 30 and ~100%, respectively)., Support by Fundação para a Ciência e Tecnologia, I.P. (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013, UID/QUI/ 00686/2013, UID/QUI/50006/2019 and UID/QUI/00686/2016. This work was funded by the R&D Project UniRCell-Unitised regenerative fuel cell for efficient renewable energy supply: from materials to device, with reference POCI-01-0145-FEDER-016422 and SAICTPAC/0032/ 2015, financed by the European Regional Development Fund (ERDF) through COMPETE 2020 – Operational Program for Competitiveness and Internationalization (POCI) and by the Foundation for Science and Technology (FCT) and CICECO-Aveiro Institute of Materials (UID/ CTM/50011/2019), financed by national funds through the FCT/MEC. Is also acknowledged, as well as funding under projects UID/CTM/ 50025/2013, Pest-OE/QUI/UI0616/2014, and LUMECD (PTDC/CTM/ NAN/0956/20149 and POCI-01-0145-FEDER-016884). F. M. Santos acknowledges a Post-PhD Fellow grant supported by Project UniRcell. P. C. Barbosa employment contract is funded by national funds (OE), through FCT – Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.R. F. P. Pereira Post-PhD fellow was funded by FCT (SFRH/BPD/87759/2012). S. C. Nunes was funded by FCT projects (Post-PhD Fellowships of UniRCell and LUMECD projects). H.M.R. Gonçalves was funded by NORTE-01-0145-FEDER-030858 and PTDC/ BTM-MAT/30858/2017.

Typical direct liquid fuel cells (DLFCs) use a liquid fuel and O2 as the oxidant. However, for applications where O2 is not available (e.g., space and underwater), the gas has been replaced by H2O2 as a liquid oxidant. This work presents a study of various ceramic disc electrodes with K2NiO4 structure and nominal compositions La2NiO4, La2CuO4, La1.9Pr0.1CuO4, La1.9Sr0.1CuO4, La1.8Ce0.2NiO4, La1.9Pr0.1NiO4, La1.8Pr0.2NiO4 and La1.9Sr0.1NiO4 to assess their stability and activity for the hydrogen peroxide reduction reaction (HPRR) in alkaline media. Stability tests conducted in 2 M NaOH show that Ni and Cu are readily dissolved, as occurs for substituting elements such as Sr, in agreement with calculated Pourbaix diagrams. Such degradation affects the surface of the materials, which is depleted of transition metals. This has consequences for the ORR and HPRR activity due to formation of a La-rich passivation layer on the surface. Only La2CuO4 and La1.8Ce0.2NiO4 display HPRR activity at around -0.25 V vs. RHE. An attempt is made to correlate the composition, chemical stability and electrochemical behaviour of these materials based on known molecular-orbital models proposed for the oxygen reduction reaction.

The present work exploits the combination of a poly(ionic liquid) and nanocellulose for the design of functional nanostructured composites with potential application as bio-based anion-exchange membranes. So, a series of nanocomposite membranes based on a tetraalkylammonium derived polymeric ionic liquid, i.e. poly(methacroylcholine chloride) (PMACC), and bacterial nanocellulose (BC) were fabricated by the in situ free radical polymerization of methacroylcholine chloride within the swollen tridimensional BC network under green reaction conditions. The ensuing nanocomposites are significantly more transparent than pristine BC and show good mechanical properties (Young's modulus = 0.46–8.42 GPa) and thermal stability up to 210–220 °C. In addition, the nanostructured membranes display high water uptake capacity and low crystallinity in comparison with pure BC, owing to the incorporation of the amorphous PMACC. The through-plane anionic conductivity of the membranes is strongly humidity-dependent and reaches a maximum of 10.0 mScm−1 (94 °C, 98% relative humidity) for the membrane with the highest content of PMACC. These promising results emphasise the potential of these anion separator nanocomposites as bio-based alternative exchange membranes for application in fuel cells and related applications.

The effect of the preferential orientation of supporting bacterial cellulose (BC) nanofibrils on the conductivity of composite proton conducting electrolytes with poly(4-styrene sulfonic acid) (PSSA) is reported. Data obtained by impedance spectroscopy show that the in-plane conductivity at 40% relative humidity (RH) is more than half order of magnitude higher than that measured through-plane, indicating significant discontinuity of proton transport at the PSSA/BC interface. The difference becomes less than 20% in nearly saturated conditions (98% RH), demonstrating the key role of water in ensuring proton transport through those interfaces. The negative impact of the conductivity anisotropy in fuel cell performance is mitigated due to operation in wet conditions and fuel cell tests of PSSA/BC-based membrane electrode assemblies under humidified hydrogen/air gradients at room temperature yield 40 mW cm-2 at 125 mA cm-2, which is amongst the highest values reported for a biopolymer-based electrolyte. It also results from the presented investigation that conventional electrode preparation used for thermoplastic polymer electrolytes must be modified in order to ensure proper adhesion to BC-based MEAs and thus to lower polarization losses.

The zeolitic imidazolate framework-8 (ZIF-8) combines a significantly high microporosity with an excellent thermal, chemical, and hydrothermal stability. Here, we demonstrated that ZIF-8 can display significant levels of protonic conductivity through a water-mediated surface transport mechanism associated to the presence of di-coordinated Zn ions revealed by X-ray photoelectron spectroscopy. A set of powders with particle sizes from 2.8 &micro, m down to 80 nm studied by dynamic water vapour sorption analysis was used to demonstrate that water adsorbs predominantly in the micropore cavities of microcrystalline ZIF-8, whereas adsorption on the external surface becomes the dominant contribution for the nanostructured material. Impedance spectroscopy in turn revealed that the protonic conductivity of the nanocrystalline ZIF-8 was two orders of magnitude higher than that of the micron-sized powders, reaching approximately 0.5 mS&middot, cm&minus, 1 at 94 &deg, C and 98% relative humidity. Simple relations were derived in order to estimate the potential gains in water uptake and conductivity as a function of the particle size. This new strategy combining particle nanostructuring with surface defects, demonstrated here for one of the most know metal organic framework, is of general application to potentially boost the conductivity of other materials avoiding chemical functionalization strategies that in most if not all cases compromise their chemical stability, particularly under high humidity and high temperature conditions.

A membrane electrolyte that restricts the methanol cross-over while retaining proton conductivity is essential for better electrochemical selectivity in direct methanol fuel cells (DMFCs). Extensive research carried out to explore numerous blends and composites for application as polymer electrolyte membranes (PEMs) revealed promising electrochemical selectivity in DMFCs of carbon nanomaterial-based polymer composites. The present review covers important literature on different carbon nanomaterial-based PEMs reported during the last decade. The review emphasises the proton conductivity and methanol permeability of nanocomposite membranes with carbon nanotubes, graphene oxide and fullerene as additives, assessing critically the impact of each type of filler on those properties.

Halophytic plants can provide an economical and environmentally sustainable source of products for human and animal feeding, in the context of the increase of worldwide emergent semi-arid landscapes. This work reports a comprehensive evaluation of the qualitative and quantitative composition of fatty acids (FA) of nineteen Mediterranean halophytes collected in southern Portugal, with the purpose of establishing their possible uses as food and feed. For FA determination, lipids and free FA were converted to the corresponding fatty acid methyl esters (FAME) and analyzed by GC-MS. Beta maritima had the highest FAME levels (7.3 mg/g DW) while Suaeda vera had the lowest content (1.0 mg/g DW). The most common saturated fatty acid (SFA) across all studied species was palmitic acid. The most prevalent monounsaturated fatty acid (MUFA) was oleic acid. Polyunsaturated fatty acids (PUFA) levels were led by linoleic acid. Less common FAMEs were also detected, namely eicosadienoic and hexadecatrienoic acids. Cotula coronopifolia, Phragmites australis and Suaeda vera displayed the best FA nutritional profiles. These species also showed bioactivities relevant for both human and animal health according to the literature and thus, collectively with this study, they could be further explored as food and feed. Agência financiadora Portuguese Foundation for Science and Technology Portuguese National Budget through the XtremeBio project PTDC/MAR-EST/4346/2012 Portuguese National Budget through GreenVet project ALG-01-0145-FEDER-028876 Portuguese Foundation for Science and Technology SFRH/BD/81425/2011 SFRH/BD/116604/2016 IF/00049/2012 FCT Scientific Employment Stimulus CEECIND/00425/2017 Portuguese National Budget UID/Multi/04326/2019 info:eu-repo/semantics/publishedVersion

Broodstock rearing conditions and handling procedures should be optimized in aquaculture species in order to benefit fish welfare and guarantee optimal conditions for spawning. In teleosts, basal cortisol levels display daily rhythms, oscillating along the 24 h of the day. In this sense, handling fish at different moments of the day may lead to different stress responses. The present study aimed at investigating the optimal rearing conditions for Senegalese sole broodstock, considering ambient light intensity and handling time. The optimal light intensity (50, 100 or 200 lx) was investigated by measuring fish cortisol levels and monitoring locomotor activity rhythms under each intensity tested. Results showed a significant increase in cortisol levels of fish exposed to 200 lx, when compared to values obtained under 100 lx, accompanied by changes in locomotor activity rhythms in both tanks under study. These results suggested that 200 lx may be too high as light intensity for this species, whereas 100 lx seems to be more adequate. Also, daily rhythms of stress response were investigated in breeders from different origins (Wild and first generation, G1). Basal cortisol levels and cortisol stress response after an acute stressor (air exposure) were monitored at two distinct moments of the day (Mid-Light and Mid-Dark). Basal levels were higher during the day in the wild group, while G1 fish seemed to have lost the daily fluctuations in basal cortisol plasma levels, as well as their daily rhythms of locomotor activity. Both groups showed lower stress responses during night-time, an indication that this is an adequate period of the day to handle this species. Senegalese sole breeders born in captivity presented more pronounced stress responses when compared to wild fish, reflecting their different life history in terms of stress challenges. FP7/SME/2008/1; UID/Multi/04326/2019; DL 57/2016/CP1361/CT0007; DL 57/2016/CP1361/CT0033 info:eu-repo/semantics/publishedVersion

This paper reports the characterization of a Nafion (R)/bacterial cellulose (BC) nanocomposite prepared by impregnation of a nanofibrillar BC membrane with Nafion (R). Such nanocomposite membrane is obtained crack-free and with thickness close to 100 mu m. Dynamic mechanical analysis reveals a storage modulus more than 1 order of magnitude higher than for pure Nafion (R), with BC effectively limiting the viscous flow of the nanocomposite up to 125 degrees C. The in-plane protonic conductivity is 0.14S cm(-1) at 94 degrees C and 98% relative humidity, which is lower than for pure Nafion (R), but in line with the lower concentration of acid groups of the composite (0.60 vs. 0.92 mmol [H+] g(-1) for Nafion (R)). The application of the Nafion (R)/BC membrane in an air/hydrogen fuel cell is demonstrated. (C) 2016 Elsevier B.V. All rights reserved.

The present study discloses a new type of nanocomposite membranes consisting of cross-linked poly(methacryloyloxyethyl phosphate) (PMOEP) and bacterial cellulose (BC) prepared by the in situ free radical polymerization of MOEP within the BC network under green reaction conditions. Homogeneous and translucent PMOEP/BC nanocomposite membranes with 52, 61 and 78 wt% of BC have good thermal and viscoelastic stability up to 180 A degrees C with storage modulus higher than 200 MPa, good mechanical properties (Young's modulus = 7.8-13.5 GPa), and high ion exchange capacity (1.95-3.38 mmol [H+] g(-1)). The protonic conductivity of these nanocomposite membranes increases with increasing PMOEP content and relative humidity (RH), reaching values higher than 0.1 S cm(-1) at 98 % RH, with activation energy close to 15 kJ mol(-1), from room temperature up to 94 A degrees C. These values are comparable to, or higher than, data typically found for a commercial Nafion(A (R)) membrane, further confirming the potential of these proton separator materials as a green alternative for application in fuel cells.

The present work aims at exploiting a polyelectrolyte nanocomposite based on poly(4-styrene sulfonic acid) (PSSA) and bacterial cellulose (BC) as an eco-friendly proton-exchange membrane (PEM) for application in microbial fuel cells (MFCs). The PSSA/BC-based PEM was confirmed as a true nanocomposite by inelastic neutron scattering (INS) vibrational spectroscopy. Moreover, this PEM exhibited thermal stability up to 155 °C, Young's modulus of 11.7 ± 0.9 GPa, ion exchange capacity of 1.85 mmol g−1, and maximum protonic conductivity of 1.73 S m−1. The application of the PSSA/BC nanocomposite membrane in a single-chamber lab-scale MFC with a pure culture of Shewanella frigidimarina yielded a maximum power density of 2.42 mW m−2, open circuit voltage of 0.436 V, and internal resistance of 15.1 kΩ. These results are superior to those obtained with a commercial Nafion® membrane and, thus, confirm the potential of this bio-based PSSA/BC nanocomposite as a PEM for MFCs.

The synthesis and characterization of nanocrystals of the zeolitic imidazolate framework-8 (ZIF8) from zinc nitrate and 2-methylimidazole (Hmim) by a colloidal chemistry route is described in the search for novel protonic conductors. The ZIF8 powders have the sodalite cubic structure with a unit cell parameter slightly in excess of 1.7 nm, a crystallite size between 30 and 50 nm, and specific surface area between 800 and 2251 m(2)g(-1), associated to high levels of microporosity and some contribution of mesopores. The impedance spectra of ZIF8 powder compacts collected under 98% relative humidity (RH) depict at least 3 contributions, which could be ascribed to the bulk resistance at high frequency, and to external interfacial phenomena at intermediate and low frequencies. The conductivity data extracted from these data display strong humidity dependence, increasing by more than 4 orders of magnitude between 20 and 98% RH at 94 degrees C, ascribed to proton transport along adsorbed water molecules. This is also supported by the enhancement of 1 order of magnitude of the conductivity of samples with highest surface area, attaining a maximum of 4.6 x 10(-4) Scm(-1) at 94 degrees C and 98% RH. The value is low, but in agreement with the reported low water uptake capacity of these materials. Surprisingly, the activation energy for conduction is as high as 110 kJmol(-1), which may denote a particular influence of the structure on proton diffusion. While the transport properties are still short for any technological application, these first results demonstrate the potential of the ZIF8 structure to combine exceptional thermal and hydrolytic stability with the potential to easily introduce high levels of proton transport by suitable functionalization. (C) 2014 Elsevier Ltd. All rights reserved.

NiO-C 0.9 Gd 0.1 O 1.95 (NiO-GDC) composites obtained using a chemical route (one-step synthesis) were characterized by thermal analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy (between 300 and 650 °C in air). Rietveld refinement of XRD data indicated that synthesized powders are ultrafine and the crystallite size of the GDC phase decreases with increasing NiO content. The relative density of sintered samples is influenced by the NiO content, but easily brought to values above 95% after sintering at 1450–1500 °C. NiO-GDC composites exhibited homogeneous phase distribution and grain size often lower than 1 µm. With 30–40 wt% NiO this phase dominates the overall electrical conductivity of NiO-GDC. The combination of grain size, conductivity and microstructural characteristics shows the efficacy of the adopted processing route to obtain high quality Ni-GDC cermet precursors.

The present study reveals the first characterization of the plasma melatonin rhythms of the meagre (Argyrosomus regius) under aquaculture conditions. Melatonin levels were monitored during a 24 h cycle under a photoperiod of 16 L:8D and under constant darkness (DD), respectively to characterize the daily rhythm of this indoleamine and to test its endogenous origin. Besides, to identify which light intensities are perceived as night or day by this species, the degree of inhibition of nocturnal melatonin production caused by increasing intensities of light was tested (3.3, 5.3, 10.5, and 120 μW/cm2), applying 1 h light pulses at Mid-Dark. The result for melatonin daily rhythm in plasma showed a typical profile: concentration remained low during all daytime points, increasing greatly during dark points, with maximum values at 16:00 and 22:00 h, zeitgeber time. Under DD conditions, the plasma melatonin profile persisted, with a similar acrophase but with a lower amplitude between subjective day and night periods, indicating this rhythm as being endogenously driven. Moreover, meagre seemed to be very sensitive to dim levels of illumination during the night, since an intensity of just 3.3 μW/cm2 inhibited melatonin production. However, only the pulse of 5.3 μW/cm2 caused a melatonin drop till daytime concentrations. Thus, the threshold of light detection by the pineal organ was suggested as being located between 3.3 and 5.3 μW/cm2. Such results are an added value for this species biology knowledge, and in consequence to its adaptation to aquaculture conditions, allowing the improvement of culture husbandry protocols.

Phosphonate- and yttrium-based metal–organic frameworks (MOFs), formulated as [Y(H5btp)]·5.5H2O (1), [Y(H5btp)]·2.5H2O (2), (H3O)[Y2(H5btp)(H4btp)]·H2O (3), and [Y(H5btp)]·H2O·0.5(MeOH) (4), were prepared using a “green” microwave-assisted synthesis methodology which promoted the self-assembly of the tetraphosphonic organic linker [1,1′-biphenyl]-3,3′,5,5′-tetrayltetrakis(phosphonic acid) (H8btp) with Y3+ cations. This new family of functional materials, isolated in bulk quantities, exhibits a remarkable breathing effect. Structural flexibility was thoroughly studied by means of X-ray crystallography, thermogravimetry, variable-temperature X-ray diffraction, and dehydration and rehydration processes, ultimately evidencing a remarkable reversible single-crystal to single-crystal (SC–SC) transformation solely through the loss and gain of crystallization solvent molecules. Topologically, frameworks remained unaltered throughout this interconversion mechanism, with all compounds being binodal 6,6-connected ne...

Green electrolytes composed of kappa-carrageenan (κ-Cg), 1-butyl-3-methyl-1H-imidazolium chloride ([Bmim]Cl) ionic liquid, and glycerol (Gly) are prepared in aqueous solution using a simple, clean, fast and low-cost procedure. A flexible membrane incorporating 50% wt [Bmim]Cl and 50% wt Gly with respect to κ-Cg exhibits the highest ionic conductivity values (8.47 ×10−4/2.45 × 10−3 S cm−1 at 20/66 °C, under anhydrous conditions, and 5.49 × 10−2/0.186 S cm−1 at 30/60 °C, at a relative humidity of 98%). Tests of room temperature air/hydrogen fuel cells incorporating κ-Cg, κ-Cg/Gly, and κ-Cg/Gly/[Bmim]Cl membranes demonstrate that these predominantly protonic conductors electrolytes are particularly well suited for the design and fabrication of eco-friendly electrochemical devices whose operation does not require the flow of gases and does not lead to water formation. These new materials have excellent application prospects in high performance (flexible) energy storage devices (supercapacitors and batteries) and electrochromic devices., This work was supported by National Funds by FCT—Foundation for Science and Technology—and by FEDER funds through the POCI— COMPETE 2020—Operational Programme Competitiveness and Internationalisation in Axis I – Strengthening research, technological development and innovation (POCI-01-0145-FEDER-007491, FCOMP01-0124-FEDER-037271, Pest-OE/QUI/UI0616/2014, Pest-C/QUI/UI0686/2013, PEst-OE/SAU/UI0709/2014, UID/CTM/50011/2013,UID/ Multi/00709/2013 and LUMECD project (POCI-01-0145- FEDER-016884 and PTDC/CTM-NAN/0956/2014)), project UniRCell (Ref. SAICTPAC/0032/2015, POCI-01-0145-FEDER-016422), by COST Action MP1202880 “Rational design of hybrid organic–inorganic interfaces” and by the Portuguese National NMR Network (RNRMN). S.C.N. acknowledge FCT for grants, Post-Ph.D. Fellowship of LUMECD project and SFRH/BPD/63152/2009. R.F.P.P., N.S., and F.M.F. acknowledge FCT for grants (SFRH/BPD/87759/2012, SFRH/ BD/89670/2012, and IF/01174/2013, respectively)., info:eu-repo/semantics/publishedVersion

This paper describes a novel method to produce poly(lactic acid) (PLA) stereocomplex (SC) crystallites directly from high molecular weight PLLA by incorporation of small quantities of choline dihydrogen phosphate ([Ch][DHP]), at room temperature. Combined results of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) confirm the formation of the PLA SC crystals. 1H NMR spectroscopy indicates a modification of the short range structural environment of choline in the blend with PLA in good agreement with the major long-range structural changes suggested by XRD, both suggesting a direct role of the choline in the PLA stereocomplexation. The electrical conductivity of these membranes measured using impedance spectroscopy is in the 6 × 10−7–4 × 10−6 S cm−1 range, which increases with increasing choline content and with increasing relative humidity (RH). The dependence on RH is weaker than for pure PLA, thus suggesting that the SC enhances the hydrophobic character of PLA, in agreement with contact angle measurements. Atomic force microscopy (AFM) and piezoresponse force microscopy (PFM) reveal a new phase with piezoelectric properties at the microsphere interfaces, with d33 corresponding to ∼60% of d33 of a periodically poled lithium niobate reference, which is directly related to the formation of SC crystalline domains. This first report of intrinsic piezoelectricity in PLA stereocomplexes opens the possibility for the development of new types of bio-based piezoactive polymers.

The development of electrochemical devices towards clean energy generation has been intensified in the last years. In this context, fuel cells, and especially intermediate temperature solid oxide fuel cells (IT-SOFC) have received much attention. Perovskite type materials of composition Ba1-xSrxCo1-yFeyO3-δ, doped or not with rare earth ions, have been quite promising because they have good ionic conductivity and operate at relatively low temperatures (500 750 °C). In this study, powders of compositions (BaSr)0.5Sm0.5Co0.8Fe0.2O3-δ (BSSCF) and (BaSr)0.5Nd0.5Co0.8Fe0.2O3-δ (BSNCF) were prepared using commercial gelatin powder as a polymerizing agent for its use as cathode. The as-prepared powders were calcined at 1000 oC and characterized by X-ray diffraction and scanning electron microscopy. Screen-printed symmetrical cells were sintered 1150 °C and studied by electrochemical impedance spectroscopy in order to assess the cathode kinetics for the oxygen reduction reaction. The best area specific resistance was found for the BSSCF cathode sintered at 1150 °C for 4 h (0.157 Ω.cm2 at 750 °C), demonstrating that this novel composition is suitable for application as SOFC cathode material. key words: Cathode, microstructure, impedance spectroscopy, IT-SOFC.

Ceria-based composites (50 vol% of the ceramic phase) including one mixture of Li and Na carbonates (1:1 molar ratio), were prepared using either pure ceria (modest conductor) or Gd-doped ceria (excellent oxide ion conductor) as ceramic matrix. These materials were aged for periods of up to 1000 h at 550 degrees C, under pure CO2, in air and in H-2 diluted in N-2, to test their stability and electrical performance. Impedance spectroscopy measurements performed between 300 and 600 degrees C were complemented by structural and microstructural characterization. The excellent long-term stability in CO2 drops slightly when moving to air and in a pronounced manner when moving to diluted H-2. In all cases and in all conditions the best performance is observed for pure ceria-based composites. Electrode (Au) and electrolyte degradation were found interrelated. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Bacterial nanocellulose (BNC) is becoming an important substrate for engineering multifunctional nanomaterials with singular and tunable properties for application in several domains. Here, antimicrobial conductive nanocomposites composed of poly(sulfobetaine methacrylate) (PSBMA) and BNC were fabricated as freestanding films for application in food packaging. The nanocomposite films were prepared through the one-pot polymerization of sulfobetaine methacrylate (SBMA) inside the BNC nanofibrous network and in the presence of poly(ethylene glycol) diacrylate as cross-linking agent. The ensuing films are macroscopically homogeneous, more transparent than pristine BNC, and present thermal stability up to 265 &deg, C in a nitrogen atmosphere. Furthermore, the films have good mechanical performance (Young&rsquo, s modulus &ge, 3.1 GPa), high water-uptake capacity (450&ndash, 559%) and UV-blocking properties. The zwitterion film with 62 wt.% cross-linked PSBMA showed bactericidal activity against Staphylococcus aureus (4.3&ndash, log CFU mL&minus, 1 reduction) and Escherichia coli (1.1&ndash, 1 reduction), and proton conductivity ranging between 1.5 &times, 10&minus, 4 mS cm&minus, 1 (40 &deg, C, 60% relative humidity (RH)) and 1.5 mS cm&minus, 1 (94 &deg, C, 98% RH). Considering the current set of properties, PSBMA/BNC nanocomposites disclose potential as films for active food packaging, due to their UV-barrier properties, moisture scavenging ability, and antimicrobial activity towards pathogenic microorganisms responsible for food spoilage and foodborne illness, and also for intelligent food packaging, due to the proton motion relevant for protonic-conduction humidity sensors that monitor food humidity levels.

Ceria-based composite electrolytes (50 and 70 vol%) including one mixture of Li and Na carbonates (1:1 molar ratio) were prepared using either pure CeO2 (modest conductor) or Gd-doped ceria (excellent oxide-ion conductor) as ceramic matrix. The composite electrolytes and their phase constituents were tested under pure CO2, air, and H-2 diluted in N-2, at temperatures ranging from 300 to 580 degrees C, to study their electrical performance. Impedance spectroscopy measurements performed under these working conditions were complemented by microstructural characterization. Low temperature (below melting) impedance shows in a clear manner the relevance of the matrix functionality on the performance of these composites, but also reveals additional microstructural and even unusual composite effects. These data were used to test equivalent circuit models derived from the composite constituent properties, and to assess their potential to design composites for target functionalities at higher temperature. (C) 2013 Elsevier Ltd. All rights reserved.

The correlation between the microstructure and electrical properties of NiO-Ce0.9Gd0.1O1.95 (NiO-CGO) composites prepared by a one-step synthesis method is reported in the present work, and compared to conventional samples synthesized by mechanically mixing commercial powders. Samples sintered between 1350 and 1450 °C had their microstructures and electrical properties investigated by scanning electron microscopy (SEM) and impedance spectroscopy. The total electrical conductivity in the range of 100 – 500 °C of one-step composites is more than one order of magnitude higher than for conventional material. This result is associated to the presence of a network of well-connected and homogeneously distributed NiO grains shown by SEM for the one-step composite, which is responsible for its improved percolative behavior and lower activation energy (0.24 eV at 250 – 650 °C).

Composite electrodes based on several ceramic oxides were tested for their chemical compatibility and electrochemical performance in systems based on composite Gd-doped ceria + alkaline carbonate electrolytes. Reactivity tests performed at 700 degrees C (accelerated testing conditions), involving the ceramic electrode materials and one mixture of Na and Li carbonates, identified two promising perovskyte-type ceramics, LaCoO3 and La0.8Sr0.2Co0.2Fe0.8O3, as the most stable. Co-pressed and co-sintered cell assemblies (electrode/electrolyte/electrode) involving composite electrodes (perovskytes mixed with alkaline carbonates)were studied in detail by scanning electron microscopy and tested by impedance spectroscopy in air in the temperature range 300-600 degrees C. These tests showed the potential of these composite electrodes for intermediate temperature applications, clearly surpassing in performance standard Au electrodes, here used as reference. (c) 2012 Elsevier Ltd. All rights reserved.

7 figuras, 3 tablas.-- © 2012. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/, The paper addresses the effect of the carbon support on the microstructure and performance of Pt–Ru-based anodes for direct methanol fuel cells (DMFC), based on the study of four electrodes with a carbon black functionalized with HNO3, a mesoporous carbon (CMK-3), a physical mixture of TiO2 and carbon black and a reference carbon thermally treated in helium atmosphere (HeTT). It is shown that CMK-3 hinders the growth of the electrocatalyst nanoparticles (2.7 nm) and improves their distribution on the support surface, whereas the oxidized surfaces of HNO3 carbon and TiO2+carbon lead to larger (4–4.5 nm), agglomerated particles, and the lowest electrochemical active areas (54 and 26 m2 g−1, in contrast with 90 m2 g−1 for CMK-3), as determined from CO stripping experiments. However, HNO3 and TiO2 are characterized by the lowest CO oxidation potential (0.4 V vs. RHE), thus suggesting higher CO tolerance for the se electrodes. Tests in DMFC configuration show that the three modified electrodes have clearly better performance than the reference HeTT. The highest power density attained with electrodes supported on carbon treated with HNO3 (65 mW cm−2/300 mA cm−2 at 90 °C) and the equally interesting performance of the TiO2-based electrodes (53 mW cm−2/300 mA cm−2), is a strong indication of the positive effect of the presence of oxygenated groups on the methanol oxidation reaction. The results are interpreted in order to identify separate microstructural (electrocatalyst particle size, porosity) and compositional (oxygenated surface groups, presence of oxide phase) effects on the electrode performance., J.R.C. Salgado acknowledges the financial support of Portuguese Foundation for Science and Technology (FCT, Science 2008) which has also partly funded this work through project HyPEM (FCT/FEDER/QREN-COMPETE PTDC/CTM-CER/109843/2009). J.R.C. Salgado and M.F. Montemor acknowledge the European Institute of Innovation and Technology, and the KIC InnoEnergy NewMat project.

Low water temperatures during winter are common in farming of gilthead sea bream in the Mediterranean. This causes metabolic disorders that in extreme cases can lead to a syndrome called “winter disease.” An improved immunostimulatory nutritional status might mitigate the effects of this thermal metabolic stress. A trial was set up to assess the effects of two different diets on gilthead sea bream physiology and nutritional state through plasma proteome and metabolites. Four groups of 25 adult gilthead sea bream were reared during winter months, being fed either with a control diet (CTRL) or with a diet called “winter feed” (WF). Proteome results show a slightly higher number of proteins upregulated in plasma of fish fed the WF. These proteins are mostly involved in the immune system and cell protection mechanisms. Lipid metabolism was also affected, as shown both by plasma proteome and by the cholesterol plasma levels. Overall, the winter feed diet tested seems to have positive effects in terms of fish condition and nutritional status, reducing the metabolic effects of thermal stress.

Individual differences in behaviour and physiological responses to stress are associated with evolutionary adaptive variation and thus raw material for evolution. In farmed animals, the interest in consistent trait associations, i.e. coping styles, has increased dramatically over the last years. However, one of limitations of the available knowledge, regarding the temporal consistency, is that it refers always to short-term consistency (usually few weeks). The present study used an escape response during a net restraining test, previously shown to be an indicative of coping styles in seabream, to investigate long-term consistency of coping styles both over time and during different life history stages. Results showed both short-term (14 days) consistency and long-term (8 months) consistency of escape response. However, we did not found consistency in the same behaviour after sexual maturation when the restraining test was repeated 16, 22 and 23 months after the first test was performed. In conclusion, this study showed consistent behaviour traits in seabream when juveniles, and a loss of this behavioural traits when adults. Therefore, these results underline that adding a life story approach to data interpretation as an essential step forward towards coping styles foreground. Furthermore, a fine-tuning of aquaculture rearing strategies to adapt to different coping strategies may need to be adjusted differently at early stages of development and adults to improve the welfare of farmed fish.

A positively charged lamellar coordination polymer based on a flexible triphosphonic acid linker is reported. [Gd(H(4)nmp)(H2O)(2)]Cl center dot 2H(2)O (1) [H(6)nmp=nitrilotris(methylene-phosphonic acid)] was obtained by a one-pot approach by using water as a green solvent and by forcing the inclusion of additional acid sites by employing HCl in the synthesis. Compound 1 acts as a versatile heterogeneous acid catalyst with outstanding activity in organic reactions such as alcoholysis of styrene oxide, acetalization of benzaldehyde and cyclohexanaldehyde and ketalization of cyclohexanone. For all reaction systems, very high conversions were reached (92-97%) in only 15-30 min under mild conditions (35 degrees C, atmospheric pressure). The coordination polymer exhibits a protonic conductivity of 1.23 x 10(-5) Scm(-1) at 98% relative humidity and 40 degrees C.

Lightweight, three-dimensional (3D) cellular structures of graphene/silicon carbide (SiC) showing very low densities (

This work reports the synthesis of nanostructured Ce1-xNixO2-δ (x = 0.05, 0.1, 0.15 and 0.2) oxides prepared by cation complexation route and with the main objective of studying their redox properties using a combination of electron microscopy, synchrotron radiation X-ray diffraction (SR-XRD) and X-ray absorption near-edge spectroscopy (XANES). The Ce1-xNixO2-δ series of nanopowders maintain the cubic crystal structure (Fm3m space group) of pure ceria, with an average crystallite size of 5-7 nm indicated by XRD patterns and confirmed by transmission electron microscopy. In situ SR-XRD and XANES carried out under reducing (5% H2/He; 5% CO/He) and oxidizing (21%O2/N2) atmospheres at temperatures up to 500 °C show a Ni solubility limit close to 15 at.% in air at room temperature, decreasing to about 10 at.% after exposure to 5% H2/He atmosphere at 500 °C. At room temperature in air, the effect of Ni on the lattice parameter of Ce1-xNixO2-δ is negligible, whereas a marked expansion of the lattice is observed at 500 °C in reducing conditions. This is shown by XANES to be correlated with the reduction of up to 25% of Ce4+ cations to the much larger Ce3+, possibly accompanied by the formation of oxygen vacancies. The redox ability of the Ce4+/Ce3+ couple in nanocrystalline Ni-doped ceria is greatly enhanced in comparison to pure ceria or achieved by using other dopants (e.g. Gd, Tb or Pr), where it is limited to less than 5% of Ce cations. Fil: Fuentes, Rodolfo Oscar. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Acuña, Leandro Marcelo. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Albornoz, Cecilia Andrea. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina Fil: Leyva, A. G.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina Fil: Sousa, N.. University of Aveiro; Portugal Fil: Figueiredo, F. M.. University of Aveiro; Portugal

The protic ionic liquid (PIL) N-butylimidazolium trifluoromethanesulfonate ([BIm][TfO]) was obtained for the first time and incorporated into a sol-gel derived di-ureasil matrix with a concentration of X = 5, 10 and 30 %, where X is the ratio of the mass of PIL per mass of poly(oxyethylene) (POE). Four years after their synthesis, the resulting quasi-anhydrous electrolytes remained amorphous, homogeneous, flexible and thermally stable below 200 ºC. SEM/EDS data revealed the presence of the PIL at the surface of the xerogels with X > 5 %, demonstrating that this type of morphological characterization is mandatory to avoid misleading ionic conductivity values. The highest ionic conductivity was produced in the washed sample with X = 30 % (3.5 x10-5 and 2.1x10-3 S cm-1 at 25 and 170 ºC, respectively). The present family of electrolytes yielded higher conductivities than the N-ethylimidazolium trifluoromethanesulfonate-based analogues introduced earlier by our group and may be thus considered as promising candidates for applications in fuel cells., Fundação para a Ciência e a Tecnologia (FCT) and when applicable by FEDER under the PT2020 Partnership Agreement for financial support (contracts PTDC/CTM - BPC/112774/2009, UID/Multi/00709/2013, PEst - C/QUI/ UI0686/2013, PEst - OE/QUI/UI0616/2014 and FCT UID/CTM/50011/2013 ) and COST Action MP1202

Propylsulfonic-acid functionalized mesoporous phenylene-silicas have potential use in catalysis and applications demanding protonic conduction such as fuel cells. Their synthesis by conventional co-condensation is time consuming and with poor control of the incorporation of sulfonic acid. Here we report a fast, microwave-assisted synthetic route to prepare these materials with controlled acid load and structural order. It is found that the microwave energy strongly improves the kinetics of the various steps of the process, including the self-assembly of precursors (stirring), consolidation of the framework (hydrothermal treatment), surfactant extraction and the oxidation of the thiol to the sulfonic acid group. The concentration of incorporated acid groups increases linearly with the self-assembly time under microwave radiation, enabling the largest improvement of all synthetic steps. However, the mesopore order decreases significantly for microwave-assisted self-assemblies in excess of 6 h, and for microwave assisted hydrothermal treatments longer than 3 h. The multivariate analysis of kinetic data is presented and used to derive kinetic parameters enabling the prediction of the acid load and the structural order of the materials as a function of the synthesis time under microwave radiation. For similar acid contents, full microwave synthesis is completed within 12 h, whereas nearly 84 h are needed with conventional heating sources. The protonic conductivity increases linearly with increasing acid load regardless of the used combination of synthetic steps, including MW or not. This is seen as a confirmation that the distribution of the acid groups in the pore surface is not affected by MW. (C) 2016 Elsevier Inc. All rights reserved.

An investigation of proton conducting periodic mesoporous benzenosilica hybrids functionalised with sulfonic or phosphonic acids obtained by a co-condensation route is presented. Protonic conductivity data obtained under different temperatures and relative humidity conditions are reported in order to assess the combined effects of composition and concentration of the functional acid group, and microstructural features such as pore size, specific surface area and meso- and molecular-scale order. It is found that the conductivity increases significantly with increasing acid load, specific surface area and relative humidity. A proton conductivity of 0.3 Sm − 1 at 100 °C and 100% relative humidity is reported for a sulfonic acid functionalised PMO which is three orders of magnitude higher than the value reported for a similar material obtained by grafting.

Sixteen different thermal profiles were used to exploit the role of thermal treatment on the structure, microstructure and electrical conductivity of yttrium- and gadolinium-doped ceria electrolytes. Samples were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and impedance spectroscopy in air. The bulk and grain boundary conductivity dependence on grain size and thermal treatment deviated from usual trends. Consistent changes in the fluorite lattice parameter with thermal history, reported here for the first time, reveal a tendency for solid solution demixing. Formation of localized concentrations of dopant cations (both in bulk and grain boundaries), explains the apparently abnormal electrical performance of these materials after prolonged thermal treatments.

The present work demonstrates that additions of lanthanum oxide can counter the negative grain boundary effects of relatively high silica contents in 8 mol% yttria-stabilized zirconia (YSZ). This can be predicted by thermodynamic analysis, showing strong affinity between silica and lanthanum oxide at typical sintering temperatures. Microstructural analysis revealed the onset of La- and Si-rich precipitates, and impedance spectroscopy confirmed a positive impact on grain boundary conductivity. Gradual oversaturation of lanthana in YSZ with decreasing temperature allows one to extend these effects by heat treatment at intermediate temperatures. This procedure enhances the positive effects of additions of lanthana on the specific grain boundary conductivity, while minimizing the negative impact on bulk conductivity.

As mammals are unable to synthesize essential polyunsaturated fatty acids (PUFA), these compounds need to be taken in through diet. Nowadays, obtaining essential PUFA in diet is becoming increasingly difficult; therefore this work investigated the suitability of using macroalgae as novel dietary sources of PUFA. Hence, 17 macroalgal species from three different phyla (Chlorophyta, Phaeophyta and Rhodophyta) were analyzed and their fatty acid methyl esters (FAME) profile was assessed. Each phylum presented a characteristic fatty acid signature as evidenced by clustering of PUFA profiles of algae belonging to the same phylum in a Principal Components Analysis. The major PUFA detected in all phyla were C-18 and C-20, namely linoleic, arachidonic and eicosapentaenoic acids. The obtained data showed that rhodophytes and phaeophytes have higher concentrations of PUFA, particularly from the n-3 series, thereby being a better source of these compounds. Moreover, rhodophytes and phaeophytes presented. healthier. Sigma(n-6/)Sigma(n-3) and PUFA/saturated fatty acid ratios than chlorophytes. Ulva was an exception within the Chlorophyta, as it presented high concentrations of n-3 PUFA, alpha-linolenic acid in particular. In conclusion, macroalgae can be considered as a potential source for large-scale production of essential PUFA with wide applications in the nutraceutical and pharmacological industries. SEABIOMED [PTDC/MAR/103957/2008]; Foundation for Science and Technology (FCT); Portuguese National Budget; FCT [SFRH/BPD/65116/2009, SFRH/BD/81425/2011]

Silicon nitride (Si3N4) processed with up to 25 vol.% of graphene nanoplatelets (GNPs) gives conductive composites with the highest electrical conductivity (40 Scm−1) reported for these ceramics with added conductive particles. During compaction and pressure-assisted densification of the composites in the spark plasma sintering (SPS), a preferred orientation of GNPs occurs. Consequently, the electrical conductivity measured along the direction perpendicular to the SPS pressing axis is more than one order of magnitude higher than the one measured along the parallel direction. Percolation in the composites is observed for 7–9 vol.% of GNPs, depending on the measuring direction, perpendicular or parallel to the pressing axis. Different conduction mechanisms are apparent for the two orthogonal orientations. Charge transport along the direction defined by the graphene ab-plane (perpendicular direction) may be explained by a two dimensional variable range hopping mechanism, whereas conduction in the parallel direction shows a more complex behavior, with a metallic-type transition (dσ/dT

Solid oxide fuel cells are extremely flexible energy conversion systems able to operate within a broad temperature range (500–1000°C), with a variety of fuels (from hydrogen to liquid fuels), including concepts able to be scaled to deliver power from the milliwatt to the megawatt range. The solid electrolyte, as an ionic charge carrier, is one central component that determines the operational characteristics of the fuel cell system, namely the working temperature. Design of new electrolytes includes manipulation of ionic defects concentration and mobility. Here, particular attention is given to the impact on ionic transport of point defects in various types of structures, dislocations, grain boundaries, and heterostructure interfaces. Properties derived from structural and compositional characteristics, but also from microstructural features, including recent complex engineered thin films, are reviewed. Major families of materials are compared with respect to key performance parameters. Finally, the effects of composition, structure, microstructure, and strain on ionic transport are assessed as complementary tools for future developments in solid electrolyte materials.

The room temperature mechanosynthesis of La 1− x Sr x Ga 1− y − z Mg y Al z O 3− δ nanopowders is successfully demonstrated for a broad compositional range ( x ≤ 0.1; y ≤ 0.2, z ≤ 0.4) by resorting to a nearly amorphous alumina precursor with enhanced reactivity. It is shown that ceramics with one single phase and free from open porosity can be obtained by sintering these nanopowders at 1350–1450 °C. Microstructural data show that the substitution of Ga by Al hinders densification and decreases the grain size of ceramics. This is explained assuming the segregation of aluminum cations to the grain boundaries as a result of the decrease of the cationic diffusion coefficients.