Dung removal increases under higher dung beetle functional diversity regardless of grazing intensification.

Dung removal by macrofauna such as dung beetles is an important process for nutrient cycling in pasturelands. Intensification of farming practices generally reduces species and functional diversity of terrestrial invertebrates, which may negatively affect ecosystem services. Here, we investigate the effects of cattle-grazing intensification on dung removal by dung beetles in field experiments replicated in 38 pastures around the world. Within each study site, we measured dung removal in pastures managed with low- and high-intensity regimes to assess between-regime differences in dung beetle diversity and dung removal, whilst also considering climate and regional variations. The impacts of intensification were heterogeneous, either diminishing or increasing dung beetle species richness, functional diversity, and dung removal rates. The effects of beetle diversity on dung removal were more variable across sites than within sites. Dung removal increased with species richness across sites, while functional diversity consistently enhanced dung removal within sites, independently of cattle grazing intensity or climate. Our findings indicate that, despite intensified cattle stocking rates, ecosystem services related to decomposition and nutrient cycling can be maintained when a functionally diverse dung beetle community inhabits the human-modified landscape.

Proactive Effect of Algae-Based Graphene Support on the Oxygen Evolution Reaction Electrocatalytic Activity of NiFe.

The preparation of graphene materials from biomass resources is still a challenge, even more so if they are going to be employed as supports for electrocatalysts for water splitting. Herein, we describe the preparation and characterization of graphene oxides (GOs) from solid macroalgae waste obtained after processing an agar-agar residue. The structural and morphological characterization of the obtained GO confirm the presence of a lamellar material that is composed of few layers with an increased number of heteroatoms (including nitrogen) if compared with those observed in a GO obtained from graphite (reference). Three-dimensional electrodes were prepared from these GOs by depositing them onto a fibrous carbon paper, followed by electrodeposition of the catalyst, NiFe. The electrocatalytic performance of these hybrid systems for the oxygen evolution reaction (OER) showed a proactive effect of both graphene materials toward catalysis. Moreover, the electrode prepared from the algae-based graphene showed the highest electrocatalytic activity. This fact could be explained by the different structure of the algae-based graphene which, due to differences in the nucleation growth patterns and electroactive sites developed during the electrodeposition process, produced more reactive NiFe species (higher oxidation state).

Floral enhancement of arable field margins increases moth abundance and diversity.

Moth populations have declined across large parts of north-western Europe since the mid-20th century due, in part, to agricultural intensification. Agri-environment schemes (AES) are widely implemented across Europe to protect biodiversity in agricultural landscapes. Grass field margins enriched with wildflowers typically out-perform grass-only margins in terms of increasing insect abundance and diversity. However, the effect of wildflower enrichment on moths remains largely unstudied. Here, the relative importance of larval hostplants and nectar resources for adult moths within AES field margins are investigated. Two treatments and a control were compared: (i) a plain grass mix, the control, (ii) a grass mix enriched with only moth-pollinated flowers, and (iii) a grass mix enriched with 13 wildflower species. Abundance, species richness and Shannon diversity were up to 1.4, 1.8 and 3.5 times higher, respectively, in the wildflower treatment compared to plain grass. The difference in diversity between treatments became greater in the second year. There was no difference in total abundance, richness or diversity between the plain grass treatment and grass enriched with moth-pollinated flowers. The increase in abundance and diversity in the wildflower treatment was due primarily to the provision of larval hostplants, with nectar provision playing a smaller role. The relative abundance of species whose larval hostplants included sown wildflowers increased in the second year, suggesting colonisation of the new habitat. Implications for insect conservation. We show that, at the farm scale, moth diversity can be greatly enhanced and abundance moderately enhanced by sowing diverse wildflower margins, providing these insects with both larval hostplants and floral resources, compared to grass-only margins. Supplementary Information: The online version contains supplementary material available at 10.1007/s10841-023-00469-9.

Population synchrony indicates functional connectivity in a threatened sedentary butterfly.

Dispersal is a key influence on species' persistence, particularly in the context of habitat fragmentation and environmental change. Previously, residual population synchrony has been demonstrated to be an effective proxy for dispersal in mobile butterflies (Powney et al. 2012). Here, we highlight the utility and limitations of population synchrony as an indicator of functional connectivity and persistence, at a range of spatial scales, in a specialist, sedentary butterfly. While at the local scale, population synchrony is likely indicative of dispersal in the pearl-bordered fritillary, Boloria euphrosyne, over larger scales, habitat is likely to influence population dynamics. Although declines in local-scale synchrony conformed to typical movement in this species, synchrony showed no significant trend with distance when studied at larger (between-site) scales. By focusing on specific site comparisons, we draw the conclusion that heterogeneity in habitat successional stage drives asynchrony between sites at larger distances and is, therefore, likely to be a more important driver of population dynamics over large distances than dispersal. Within-site assessments of synchrony highlight differences in dispersal based on habitat type, with movement shown to be most inhibited between transect sections with contrasting habitat permeability. While synchrony has implications for metapopulation stability and extinction risk, no significant difference was found in average site synchrony between sites that had gone extinct during the study period and those remaining occupied. We demonstrate that population synchrony may be used to assess local-scale movement between sedentary populations, as well as to understand barriers to dispersal and guide conservation management.

A trait-based framework for dung beetle functional ecology.

Traits are key for understanding the environmental responses and ecological roles of organisms. Trait approaches to functional ecology are well established for plants, whereas consistent frameworks for animal groups are less developed. Here we suggest a framework for the study of the functional ecology of animals from a trait-based response-effect approach, using dung beetles as model system. Dung beetles are a key group of decomposers that are important for many ecosystem processes. The lack of a trait-based framework tailored to this group has limited the use of traits in dung beetle functional ecology. We review which dung beetle traits respond to the environment and affect ecosystem processes, covering the wide range of spatial, temporal and biological scales at which they are involved. Dung beetles show trait-based responses to variation in temperature, water, soil properties, trophic resources, light, vegetation structure, competition, predation and parasitism. Dung beetles' influence on ecosystem processes includes trait-mediated effects on nutrient cycling, bioturbation, plant growth, seed dispersal, other dung-based organisms and parasite transmission, as well as some cases of pollination and predation. We identify 66 dung beetle traits that are either response or effect traits, or both, pertaining to six main categories: morphology, feeding, reproduction, physiology, activity and movement. Several traits pertain to more than one category, in particular dung relocation behaviour during nesting or feeding. We also identify 136 trait-response and 77 trait-effect relationships in dung beetles. No response to environmental stressors nor effect over ecological processes were related with traits of a single category. This highlights the interrelationship between the traits shaping body-plans, the multi-functionality of traits, and their role linking responses to the environment and effects on the ecosystem. Despite current developments in dung beetle functional ecology, many knowledge gaps remain, and there are biases towards certain traits, functions, taxonomic groups and regions. Our framework provides the foundations for the thorough development of trait-based dung beetle ecology. It also serves as an example framework for other taxa.

Grand challenges in entomology: Priorities for action in the coming decades.

Entomology is key to understanding terrestrial and freshwater ecosystems at a time of unprecedented anthropogenic environmental change and offers substantial untapped potential to benefit humanity in a variety of ways, from improving agricultural practices to managing vector-borne diseases and inspiring technological advances.We identified high priority challenges for entomology using an inclusive, open, and democratic four-stage prioritisation approach, conducted among the membership and affiliates (hereafter 'members') of the UK-based Royal Entomological Society (RES).A list of 710 challenges was gathered from 189 RES members. Thematic analysis was used to group suggestions, followed by an online vote to determine initial priorities, which were subsequently ranked during an online workshop involving 37 participants.The outcome was a set of 61 priority challenges within four groupings of related themes: (i) 'Fundamental Research' (themes: Taxonomy, 'Blue Skies' [defined as research ideas without immediate practical application], Methods and Techniques); (ii) 'Anthropogenic Impacts and Conservation' (themes: Anthropogenic Impacts, Conservation Options); (iii) 'Uses, Ecosystem Services and Disservices' (themes: Ecosystem Benefits, Technology and Resources [use of insects as a resource, or as inspiration], Pests); (iv) 'Collaboration, Engagement and Training' (themes: Knowledge Access, Training and Collaboration, Societal Engagement).Priority challenges encompass research questions, funding objectives, new technologies, and priorities for outreach and engagement. Examples include training taxonomists, establishing a global network of insect monitoring sites, understanding the extent of insect declines, exploring roles of cultivated insects in food supply chains, and connecting professional with amateur entomologists. Responses to different challenges could be led by amateur and professional entomologists, at all career stages.Overall, the challenges provide a diverse array of options to inspire and initiate entomological activities and reveal the potential of entomology to contribute to addressing global challenges related to human health and well-being, and environmental change.

Moth declines are most severe in broadleaf woodlands despite a net gain in habitat availability.

While agricultural intensification and habitat loss are cited as key drivers of moth decline, these alone cannot explain declines observed in UK woodlands - a habitat that has expanded in area since 1968.We quantified how moth communities changed across habitats and regions and determined how species traits interacted with habitat in predicting moth abundance change. We hypothesised that, in woodlands, species more vulnerable to shading and browsing by deer (species specialising on forbs, shrubs and shade-intolerant plants) had declined more severely than other species, and that moth decline in woodlands was more severe at sites more susceptible to deer damage.We modelled abundance, biomass, species richness and diversity from 1968 to 2016 and explored how these interacted with habitat and region. We also modelled the interaction between habitat and two moth species traits: larval feeding guild and shade-tolerance of hostplant.Moth declines were consistently highest in broadleaf woodland. Abundance, biomass, species richness and diversity declined significantly by -51%, -52%, -14% and -15% in woodlands, respectively, compared to national trends of -34%, -39%, -1% (non-significant) and +10%. Declines were no greater in woodlands more susceptible to deer browsing damage. Traits based analysis found no evidence that shading and intensive browsing by deer explained moth declines in woodland.Moth decline was more severe in broadleaf woodlands than in intensively managed farmlands. We found no evidence that deer browsing or increased shading has driven these trends: the primary cause of the decline of moths in woodlands remains unclear.

Evaluation of different internal standardization approaches for the quantification of melatonin in cell culture samples by multiple heart-cutting two dimensional liquid chromatography tandem mass spectrometry.

We evaluate here different analytical strategies for the chromatographic separation and determination of N-acetyl-5-methoxytryptamine (MEL) and its oxidative metabolites N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), N1-acetyl-5-methoxykynuramine (AMK) and cyclic 3-hydroxymelatonin (c3OHM) in cell culture samples. Two dimensional liquid chromatography (2D-LC) in the multiple heart-cutting mode was compared with regular 1D chromatographic separations of MEL and its oxidative metabolites. Our results showed that the use of trifluoroacetic acid (TFA) as mobile phase modifier was required to obtain a satisfactory resolution and peak shapes particularly for c3OHM. As TFA is not compatible with ESI ionization the application of the MHC mode was mandatory for a proper chromatographic separation. We evaluate also different internal standardization approaches based on the combined use of a surrogate standard (5-methoxytryptophol) and an internal standard (6-methoxytryptamine) for MEL quantification in cell culture samples obtaining unsatisfactory results both by 1D- and 2D-LC-ESI-MS/MS (from 9 ± 2 to 186 ± 38%). We demonstrate that only the application of isotope dilution Mass Spectrometry through the use of an in house synthesized 13C isotopically labelled analogue provided quantitative MEL recoveries both by using 1D- and 2D-LC-ESI-MS/MS (99±1 and 98±1. Respectively) in androgen-insensitive human prostate carcinoma PC3 cells.

Reduced graphene oxide membranes in ocular regenerative medicine.

Biological membranes are currently used in Ophthalmology in order to treat different ocular disorders. These membranes have different properties such as cellular biocompatibility and promoting wound healing. Moreover, intrinsic antimicrobial properties could also be desirable because it would allow their use reducing the risk of infections. Graphene and its derivatives are promising biomaterials that already proved their bactericidal effect. However, their clinical use is limited due to the controversial results regarding their toxicity. In this work, we have developed and characterized a reduced graphene oxide membrane (rGOM) for its use in ocular Regenerative Medicine, and studied its in vitro and in vivo biocompatibility and genotoxicity with different types of human ocular cells. We proved that rGOM allowed the growth of different ocular cells without inducing in vitro or in vivo cytotoxicity or genotoxicity in the short-term. These results indicate that rGOM may be a promising candidate in Regenerative Medicine for the treatment of different ocular pathologies.

How butterflies keep their cool: Physical and ecological traits influence thermoregulatory ability and population trends.

Understanding which factors influence the ability of individuals to respond to changing temperatures is fundamental to species conservation under climate change. We investigated how a community of butterflies responded to fine-scale changes in air temperature, and whether species-specific responses were predicted by ecological or morphological traits. Using data collected across a UK reserve network, we investigated the ability of 29 butterfly species to buffer thoracic temperature against changes in air temperature. First, we tested whether differences were attributable to taxonomic family, morphology or habitat association. We then investigated the relative importance of two buffering mechanisms: behavioural thermoregulation versus fine-scale microclimate selection. Finally, we tested whether species' responses to changing temperatures predicted their population trends from a UK-wide dataset. We found significant interspecific variation in buffering ability, which varied between families and increased with wing length. We also found interspecific differences in the relative importance of the two buffering mechanisms, with species relying on microclimate selection suffering larger population declines over the last 40 years than those that could alter their temperature behaviourally. Our results highlight the importance of understanding how different species respond to fine-scale temperature variation, and the value of taking microclimate into account in conservation management to ensure favourable conditions are maintained for temperature-sensitive species.

Multifunctional Silicone Rubber Nanocomposites by Controlling the Structure and Morphology of Graphene Material.

Multifunctional elastomer nanocomposites have been applied in several high-tech fields. The design of materials with tailored properties capable of tuning their performance is a topical challenge. Here, we demonstrate that it is possible to modulate the mechanical and transport properties of silicone rubber nanocomposites by controlling the structure, chemical composition and morphology of the graphene material. Intrinsic graphene properties, such as remaining oxygen groups, specific surface area, and aspect ratio, among others, have a profound effect on the final properties of the nanocomposite. Thus, the thermal conductivity benefits from larger filler size and high aromatic restoration. Whereas mechanical properties and electrical conductivity require a proper balance between filler/polymer matrix interaction and a partial aromatic restoration.

Accurate and sensitive determination of molar fractions of 13C-Labeled intracellular metabolites in cell cultures grown in the presence of isotopically-labeled glucose.

This work describes a methodology based on multiple linear regression and GC-MS for the determination of molar fractions of isotopically-labeled intracellular metabolites in cell cultures. Novel aspects of this work are: i) the calculation of theoretical isotopic distributions of the different isotopologues from an experimentally measured value of % 13C enrichment of the labeled precursor ii) the calculation of the contribution of lack of mass resolution of the mass spectrometer and different fragmentation mechanism such as the loss or gain of hydrogen atoms in the EI source to measure the purity of the selected cluster for each metabolite and iii) the validation of the methodology not only by the analysis of gravimetrically prepared mixtures of isotopologues but also by the comparison of the obtained molar fractions with experimental values obtained by GC-Combustion-IRMS based on 13C/12C isotope ratio measurements. The method is able to measure molar fractions for twenty-eight intracellular metabolites derived from glucose metabolism in cell cultures grown in the presence of 13C-labeled Glucose. The validation strategies demonstrate a satisfactory accuracy and precision of the proposed procedure. Also, our results show that the minimum value of 13C incorporation that can be accurately quantified is significantly influenced by the calculation of the spectral purity of the measured cluster and the number of 13C atoms of the labeled precursor. The proposed procedure was able to accurately quantify gravimetrically prepared mixtures of natural and labeled glucose molar fractions of 0.07% and mixtures of natural and labeled glycine at molar fractions down to 0.7%. The method was applied to initial studies of glucose metabolism of different prostate cancer cell lines.

Evaluation of sulfur isotopic enrichment of urine metabolites for the differentiation of healthy and prostate cancer mice after the administration of 34S labelled yeast.

Sulfur isotopic enrichment of urine metabolites in healthy and prostate cancer mice using 34S enriched yeast and High Performance Liquid Chromatography coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (HPLC-MC-ICP-MS) has been evaluated. A 30 weeks experiment (since the eleventh to the fortieth week of life) was carried out collecting the urine of three healthy mice and three transgenic mice with prostate cancer during 24h after a single oral administration of a 34S enriched yeast slurry. The isotopic enrichment of different sulphur metabolites was monitored by coupling a C18 reverse phase HPLC column with a multicollector ICP-MS using a membrane desolvating system. Quantification of sulfur in the chromatographic peaks was carried out by post-column isotope dilution using a 33S enriched spike. Differences between the 34S enrichment in the urine metabolites of healthy and prostate cancer mice were found from the beginning of the disease. Both populations could be differentiated using a principal component analysis (PCA). Finally, 7 unknown mice were correctly classified in each population using a linear discriminant analysis.

Behavior of Listeria monocytogenes in Sliced Ready-to-Eat Meat Products Packaged under Vacuum or Modified Atmosphere Conditions.

The objective of this research was to determine the behavior of Listeria monocytogenes in three types of sliced ready-to-eat meat products packaged under vacuum or modified atmosphere conditions and stored at three temperatures. Slices of about 25 g of chorizo (a fermented dry pork sausage), jamón (cured ham), and cecina (a salted, dried beef product) were inoculated with L. monocytogenes NCTC 11994. Slices were packaged in a vacuum or in a modified atmosphere (20% CO2, 80% N2). After packaging, samples were stored for 6 months at three temperatures: 3, 11, or 20°C. Microbiological analyses were performed after 0, 1, 7, 15, 30, 45, 90, and 180 days of storage. The type of meat product, the type of packaging, the temperature, and the day of storage all influenced microbial levels (P < 0.001). L. monocytogenes counts decreased throughout the course of storage in samples of chorizo (quick decrease) and jamón (gradual decrease). In cecina samples, counts of L. monocytogenes increased from day 0 to day 1 of storage and then remained constant until day 90 of the study. These results may be of use for enhancing the safety of these ready-to-eat meat product types. Additional evaluation of the behavior of L. monocytogenes in cecina is needed.

FATTY ACID PROFILE OF TWO CURED MEAT PRODUCTS: DRY-CURED HAM AND CECINA.

INTRODUCTION AND OBJECTIVES: the aim of this study was to assess the fatty acid profile of two cured meat products of similar manufacturing processes and characteristics, dry-cured ham (JA) and cecina (CE), a type of dry-cured beef. The obtained results were discussed in terms of the effects that each singular fatty acid, when consumed, could have on human health. MATERIALS AND METHODS: for this purpose, 10 samples of 100 g of JA and CE were obtained in local food stores in León, Spain. Lipids were extracted and transesterified, then a gas chromatography-mass was used to analyze the samples. RESULTS AND DISCUSSION: results for fatty acid profiles for JA and CE showed significant differences (p < 0.01), with these values for main lipids fractions, saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), respectively: 42.86%, 43.27% and 13.87 for JA and 46.87%, 46.96% and 6.20% for CE. SFA and MUFA percentages were slightly higher in CE at the expense of PUFA, specifically in the n-6 series, where values of 11.06% in JA and 3.91% in CE were obtained. In both products, the most prevalent fatty acid was a monounsaturated fatty acid, oleic acid, with percentages of 37.28% in JA and 38.48% in CE. Other fatty acids with higher percentages, with respect to total fat, were two saturated fatty acids: palmitic acid, 20.63% in JA and 22.95% in CE, and stearic acid, 18.65% in JA and 17.14% in CE.

Introducción y objetivos: el objetivo de este estudio fue evaluar el perfil de ácidos grasos de dos derivados cárnicos curados-madurados, relativamente similares en cuanto a composición y proceso de elaboración: el jamón (JA) y la cecina (CE), haciendo una revisión de los resultados obtenidos desde el punto de vista de los efectos individuales que los principales ácidos grasos de consumo dietético tienen sobre la salud humana. Materiales y métodos: para ello se tomaron 10 muestras de 100 g de jamón y de cecina en distintos establecimientos de la provincia de León, España. Se extrajo la grasa y se metiló para posteriormente realizar el análisis de los ácidos grasos resultantes mediante cromatografía de gases masas. Resultados y discusión: los perfiles lipídicos obtenidos para el JA y la CE presentaron diferencias significativas (p < 0,01), con los siguientes valores para las fracciones lipídicas mayoritarias, ácidos grasos saturados (SFA), ácidos grasos monoinsaturados (MUFA) y ácidos grasos poliinsaturados (PUFA), respectivamente: 42,86%, 43,27% y 13,87 para el JA y 46,87%, 46,96% y 6,20% para la CE. Los porcentajes de SFA y MUFA fueron mayores en la CE en detrimento de los PUFA, en concreto de la serie n-6, para la que se obtuvieron valores de 11,06% en JA y de 3,91% en CE. En ambos productos el ácido graso detectado en mayor cantidad fue un ácido graso monoinsaturado, el ácido oleico, con porcentajes del 37,28% en JA y 38,48% en CE. Otros dos ácidos grasos presentes en porcentajes elevados respecto al total de la grasa fueron dos ácidos grasos saturados: el ácido palmítico, 20,63% en JA y 22,95% en CE, y el ácido esteárico, 18,65% en JA y 17,14% en CE.

Fatty acid profile of two cured meat products: dry-cured ham and cecina / Perfil de ácidos grasos de dos derivados cárnicos curados-madurados: jamón y cecina

Introduction and objectives: the aim of this study was to assess the fatty acid profile of two cured meat products of similar manufacturing processes and characteristics, dry-cured ham (JA) and cecina (CE), a type of dry-cured beef. The obtained results were discussed in terms of the effects that each singular fatty acid, when consumed, could have on human health. Materials and methods: for this purpose, 10 samples of 100 g of JA and CE were obtained in local food stores in León, Spain. Lipids were extracted and transesterified, then a gas chromatography-mass was used to analyze the samples. Results and discussion: results for fatty acid profiles for JA and CE showed significant differences (p < 0.01), with these values for main lipids fractions, saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), respectively: 42.86%, 43.27% and 13.87 for JA and 46.87%, 46.96% and 6.20% for CE. SFA and MUFA percentages were slightly higher in CE at the expense of PUFA, specifically in the n-6 series, where values of 11.06% in JA and 3.91% in CE were obtained. In both products, the most prevalent fatty acid was a monounsaturated fatty acid, oleic acid, with percentages of 37.28% in JA and 38.48% in CE. Other fatty acids with higher percentages, with respect to total fat, were two saturated fatty acids: palmitic acid, 20.63% in JA and 22.95% in CE, and stearic acid, 18.65% in JA and 17.14% in CE (AU)

Introducción y objetivos: el objetivo de este estudio fue evaluar el perfil de ácidos grasos de dos derivados cárnicos curados-madurados, relativamente similares en cuanto a composición y proceso de elaboración: el jamón (JA) y la cecina (CE), haciendo una revisión de los resultados obtenidos desde el punto de vista de los efectos individuales que los principales ácidos grasos de consumo dietético tienen sobre la salud humana. Materiales y métodos: para ello se tomaron 10 muestras de 100 g de jamón y de cecina en distintos establecimientos de la provincia de León, España. Se extrajo la grasa y se metiló para posteriormente realizar el análisis de los ácidos grasos resultantes mediante cromatografía de gases masas. Resultados y discusión: los perfiles lipídicos obtenidos para el JA y la CE presentaron diferencias significativas (p < 0,01), con los siguientes valores para las fracciones lipídicas mayoritarias, ácidos grasos saturados (SFA), ácidos grasos monoinsaturados (MUFA) y ácidos grasos poliinsaturados (PUFA), respectivamente: 42,86%, 43,27% y 13,87 para el JA y 46,87%, 46,96% y 6,20% para la CE. Los porcentajes de SFA y MUFA fueron mayores en la CE en detrimento de los PUFA, en concreto de la serie n-6, para la que se obtuvieron valores de 11,06% en JA y de 3,91% en CE. En ambos productos el ácido graso detectado en mayor cantidad fue un ácido graso monoinsaturado, el ácido oleico, con porcentajes del 37,28% en JA y 38,48% en CE. Otros dos ácidos grasos presentes en porcentajes elevados respecto al total de la grasa fueron dos ácidos grasos saturados: el ácido palmítico, 20,63% en JA y 22,95% en CE, y el ácido esteárico, 18,65% en JA y 17,14% en CE (AU)

Dielectric behavior of ceramic-graphene composites around the percolation threshold.

Al2O3/graphene and BaTiO3/graphene composites with different concentrations of the conductive second phase, both below and above the percolation threshold, were prepared by the traditional ceramic processing route followed by spark plasma sintering. It is shown that the addition of graphene pins the grain growth of the ceramic matrix grains, leading to a change of the microstructure at low filler concentrations. As a consequence, the composites exhibit two percolation thresholds and their dielectric properties are not only determined by the dielectric properties of the constituents and their relative fractions but also the microstructure of the composite must be considered. Additionally, a giant increase of the dielectric constant has been found around the percolation thresholds in barium titanate-graphene composites. In particular, values of the dielectric constant up to 45,000 and 15,000 were found at 1 kHz in composites containing 0.4 and 0.6 wt. % graphene, respectively.

An approach to classification and capacitance expressions in electrochemical capacitors technology.

The proliferation of novel types and designs of electrochemical capacitors makes it necessary to obtain a better understanding of the behavior of these systems together with a more systematic classification of them. In this study a rational classification of supercapacitors based on the charge storage mechanism and the active material of each electrode is proposed. The internationally accepted terminology - the terms symmetric, asymmetric and hybrid - is also clarified in an attempt to standardize the current definitions and facilitate the systematic classification of each device. Additionally, the selection of suitable mathematical expressions to calculate the capacitance of each kind of system is rationalized throughout the discussion taking into account the behavioral characteristics of each electrode. An examination of the potential evolution profile of each electrode during the galvanostatic cycling of the supercapacitor is presented as a key tool for understanding the fundamental behavior of these devices.

High-intensity ultrasonication as a way to prepare graphene/amorphous iron oxyhydroxide hybrid electrode with high capacity in lithium battery.

The preparation of graphene/iron oxyhydroxide hybrid electrode material with very homogeneous distribution and close contact of graphene and amorphous iron oxyhydroxide nanoparticles has been achieved by using high-intensity ultrasonication. Due to the negative charge of the graphene surface, iron ions are attracted toward the surface of dispersed graphene, according to the zeta potential measurements. The anchoring of the FeO(OH) particles to the graphene layers has been revealed by using mainly TEM, XPS and EPR. TEM observations show that the size of the iron oxide particles is about 4 nm. The ultrasonication treatment is the key parameter to achieve small particle size in these graphene/iron oxyhydroxide hybrid materials. The electrochemical behavior of composite graphene/amorphous iron oxyhydroxide prepared by using high-intensity ultrasonication is outstanding in terms of gravimetric capacity and cycling stability, particularly when metallic foam is used as both the substrate and current collector. The XRD-amorphous character of iron oxyhydroxide in the hybrid electrode material and the small particle size contribute to achieve the improved electrochemical performance.

Tailoring micro-mesoporosity in activated carbon fibers to enhance SO2 catalytic oxidation.

Enhanced SO2 adsorption of activated carbon fibers is obtained by tailoring a specific micro-mesoporous structure in the fibers. This architecture is obtained via metal catalytic activation of the fibers with a novel precursor, cobalt naphthenate, which contrary to other precursors, also enhances spinnability and carbon fiber yield. In the SO2 oxidation, it is demonstrated that the combination of micropores and large mesopores is the main factor for an enhanced catalytic activity which is superior to that observed in other similar microporous activated carbon fibers. This provides an alternative way for the development of a new generation of catalytic material.