Solid-state carbon-based textile supercapacitors for energy storage applications

In this work, carbon-based conducting electrodes based on two different types of carbon nanofibers (CNF) have been produced by the dip and dry coating method onto cotton substrates. Furthermore, activated carbon (Norit A Supra Eur) and manganese oxide (MnO2) have been subsequenlty added to the CNF-based dip-coated cotton fabrics electrodes and asymmetric supercapacitors have been constructed and tested with the focus of obtaining devices with increased capacitive performance. In particular, the carbon-based active layer was prepared by spreading on the CNF-based electrodes a slurry containing the activated carbon (AC) material, graphite fibres, polyvinylidene difluoride (PVDF) as binder and N,N dimethylacetamide (DMA) solvent, whereas the MnO2 based active layer was prepared by spreading on the CNF-based textile electrodes a slurry formed by MnO2, carbon black, graphite fibers, PVDF and DMA. A solution of 1M Na2SO4 impregnated in porous paper separator (Nippon Kodoshi Corportion, Japan) was employed as neutral aqueous electrolyte. The supercapacitors were electrochemical investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results indicated that with this particular combination of carbon and manganese oxide active layers on CNF-based cotton fabrics it was possible to obtain specific capacitance of 100 F/g and a high specific energy density of 10 Wh/kg.This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136. A. J. Paleo acknowledges the support of COST Action CA15107- Multi-Functional Nano-Carbon Composite Materials Network (MultiComp) by means of a short term scientific mission (STSM).info:eu-repo/semantics/publishedVersio

Supercapacitors based on AC/MnO2 deposited onto dip-coated carbon nanofiber cotton fabric electrodes

This work introduces the preparation of flexible carbon composite electrodes based on the top-down approach starting from the dip-coating of carbon nanofibers (CNFs) onto a cotton fabric. On these so-obtained conductive cotton fabrics, further layers of activated carbon and manganese oxide (MnO2) materials were subsequently added to enhance the electrochemical performances of negative and positive electrodes. At the end, two different types of asymmetric supercapacitors (SCs) were assembled with those textile electrodes by using porous paper and Nafion-Na ion-exchange membranes as separators. The different SCs were electrochemically characterized by means of cyclic voltammetry (CV), galvanostatic charge/discharge (G–CD) and electrochemical impedance spectroscopy (EIS). These hybrid carbon-based textile SCs exhibited capacitance performance of 138 and 134 F g–1 with the porous paper and Nafion membrane, respectively, and low self-discharge rates. Furthermore, in this study is considered the combination of two methods (cycling and floating) for studying the long-term durability tests of SCs. In particular, the floating methodology utilizes much more harsh conditions than the common cycling based on G-CD tests at high currents usually discussed in literature. The solid-state (Nafion membrane) hybrid device demonstrated very long durability with 10 K cycles and additional 270 h at a constant voltage of 1.6 V. In summary, the hybrid SCs fabricated with low cost materials and simple methodologies reported in this study showed very promising results for flexible energy storage applications.This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology (project POCI-01-0145-FEDER-007136). A.J. Paleo acknowledges the European COST Action CA15107- Multi-Functional Nano-Carbon Composite Materials Network (MultiComp) for its support with a Short Term Scientific Mission (STSM) grant at CNR-ITAE of Messina

Lifetime assessment of solid-state hybrid supercapacitors based on cotton fabric electrodes

Electrodes based on activated carbon and manganese oxide coated on a cotton woven fabric were developed and investigated. The electrodes were then assembled with two polymer electrolyte membranes, Nafion®115 and Aquivion®E87-05S, and two different supercapacitors were produced with specific capacitances and energy densities of 130 and 132 F g−1, and 11.5 and 11.7 Wh kg−1, respectively. Furthermore, a new durability methodology, which combines galvanostatic charge/discharge cycles together with potentiostatic floating conditions, was used to get insight into their electrochemical performance under stringent conditions. The supercapacitor assembled with Nafion®115 electrolyte worked successfully for 10 k cycles and 140 h under a constant voltage of 1.6 V (floating condition), whereas the supercapacitor assembled with Aquivion®E87-05S electrolyte worked successfully for more than 15 k cycles and 210 h, without any appreciable degradation of their electrochemical properties. In summary, hybrid solid-state supercapacitors based on electrodes produced by simple methodologies and low-cost materials, and with long durability performance under very harsh conditions were developed and analysed for their potential utilization as flexible energy storage devices.This work was supported by Project UID/CTM/00264/2019 of 2C2T – Centro de Ciência e Tecnologia Têxtil, funded by National Founds through FCT/MCTES. This research was also partially supported by the Cost Action 15107, Grant No. ECOST-STSM-CA15107-300118-092731

Plasma levels of ghrelin, des-acyl ghrelin and LEAP2 in children with obesity: Correlation with age and insulin resistance

Objective: The octanoylated peptide hormone ghrelin regulates appetite and glycaemic control. Des-acyl ghrelin abolishes some effects of ghrelin, but does not bind to ghrelin receptor. LEAP2 is a novel ligand for ghrelin receptor that blocks the effects of ghrelin. Some evidences show that plasma levels of these peptides are altered adults with obesity, but their levels in childhood obesity remain poorly studied. Therefore, the objective of this study was to assess fasting plasma levels of ghrelin, des-acyl ghrelin and LEAP2 in children with normoweight, overweight/obesity and their association with different anthropometric and metabolic variables. Design: A total of 42 females and 40 males, ages 3-12 years-old were enrolled as a cross-sectional cohort. Results: Plasma levels of des-acyl ghrelin and LEAP2 (but not ghrelin) were lower and ghrelin/des-acyl ghrelin ratio was higher in children with overweight/obesity. Des-acyl ghrelin negatively correlated with age, BMI z-score, insulin and HOMA index, and the correlations were stronger in children with overweight/obesity. LEAP2 levels negatively correlated with BMI z-score. No gender differences were found. Conclusions: Our findings suggest that ghrelin tone is increased in childhood obesity, due to a decrease on plasma levels of des-acyl ghrelin and LEAP2, and that des-acyl ghrelin is associated to insulin resistance, particularly in children with overweight/obesity.Fil: Fittipaldi, Antonela Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Hernandez, Julieta. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de La Plata. Instituto de Desarrollo e Investigaciones Pediátricas; ArgentinaFil: Castrogiovanni, Daniel Cayetano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Lufrano, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: de Francesco, Pablo Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; ArgentinaFil: Garrido, Verónica. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de La Plata. Instituto de Desarrollo e Investigaciones Pediátricas; ArgentinaFil: Vitaux, Patrick. Bertin Technologies; FranciaFil: Fasano, María Victoria. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; Argentina. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de La Plata. Instituto de Desarrollo e Investigaciones Pediátricas; ArgentinaFil: Fehrentz, Jean Alain. Bertin Technologies; Francia. Université Montpellier II; FranciaFil: Fernández, Adriana. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de La Plata. Instituto de Desarrollo e Investigaciones Pediátricas; ArgentinaFil: Andreoli, María F.. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de La Plata. Instituto de Desarrollo e Investigaciones Pediátricas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perello, Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular; Argentin

Hydrolysis of caprine and ovine milk proteins, brought about by aspartic peptidases from <i>Silybum marianum</i> flowers

The flowers of cardoon (Asteraceae) are a rich source of aspartic peptidases which possess milk clotting activity – and are thus used in traditional cheesemaking in the Iberian Peninsula. This study was aimed at characterizing the enzymatic action of the aspartic peptidases present in flowers of Silybum marianum (L.) Gaertn. (Asteraceae), specifically upon degradation of caseins. The proteolytic activities toward Na-caseinates previously prepared from caprine and ovine milks were studied, in a comparative fashion, using urea-PAGE, tricine-SDS-PAGE, densitometry, electroblotting and sequencing. Caprine αs1- and β-caseins were degraded up to 68% and 40%, respectively, during 24 h of incubation. Only one important and well-defined band corresponding to a molecular weight of 14.4 kDa – i.e. a fragment of β-casein, was observed by 12 h of hydrolysis. By 24 h of incubation, ovine αs- and β-caseins were degraded up to 76% and 19%, respectively. In what concerns specificity, the major cleavage site in ovine caseinate was Leu99-Arg100 in αs1-casein.Centro de Investigación de Proteínas Vegetale

Biochemical and PMF MALDI-TOF analyses of two novel papain-like plant proteinases

Two cysteine endopeptidases from latex of Araujia angustifolia (araujiain aI and araujiain aIII) were purified and characterized by means of conventional and proteomics techniques (MALDI-TOF). N-terminal sequences showed a high percentage of identity with cysteine proteinases belonging to the papain family. The peptide mass fingerprint analysis demonstrated a close homology among both proteinases.Centro de Investigación de Proteínas Vegetale

Nafion® as advanced immobilisation substrate for the voltammetric analysis of electroactive microparticles: the case of some artistic colouring agents

Voltammetry of microparticles is applied to characterise and to identify solid analytes of interest in the field of cultural heritage. Nafion® is used for the immobilisation of solid microparticles onto the surface of a glassy carbon electrode by exploiting the deposition onto the electrode surface of a micro-volume of a suspension of the microsample in polymeric solution. Cyclic voltammetry and square wave voltammetry are applied to characterise and to identify the microparticles immobilised in the Nafion® coating. The analyte studied in this work is Prussian Blue as a typical inorganic pigment, with a relatively simple electrochemical behaviour. The proposed method is applied to a sample of Venetian marmorino plaster. The performance of Nafion® for this analysis is compared with that of the polymer Paraloid B72

Virtual special issue on the “HYdrogen POwer - THeoretical and Engineering Solutions - International Symposium (Hypothesis XII)”

[No abstract available