Estrategias y supuestos: relatividad conceptual versus inconmensurabilidad

Bajo el supuesto de una conexión íntima entre inconmensurabilidad y relativismo (total), Hilary Putnam diseña argumentos de refutación para una y otra tesis. Esto lo encontramos en un capítulo de Razón, Verdad e Historia (1981), titulado "Dos concepciones de la Racionalidad". La primer parte del capítulo analiza el fracaso del positivismo lógico (como 'racionalidad clásica'), en un segundo apartado, llamado "El Anarquismo se autorrefuta", desarrolla los argumentos que aquí nos interesan, dirigidos a demostrar lo insostenible de la tesis de la inconmensurabilidad y del relativismo (total)

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

Development of carbon/MnO₂ coated on nanofiber textile electrodes for hybrid solid-state supercapacitors

This work is focused on the design and development of hybrid solid-state energy storage devices with high capacitive performance. In particular, the work includes, the preparation of carbon composite electrodes based on a carbon nanofibers (CNF) supported on a cotton fabric. The coating of CNF to the cotton cloth is obtained by the dip and dry method. On these so-obtained composite substrates, further layers of activated carbon (Norit A Supra Eur) and manganese oxide (MnO2) material have been subsequenlty deposited to enhance the electrochemical performances of negative and positive electrodes, respectively. The preparation of carbon-based active layers comprises the spreading on the negative CNF-substrate of a slurry containing the activated carbon (AC) material, graphite fibres and polyvinylidene difluoride (PVDF) in N,N dimethylacetamide (DMA). Whereas the positive electrode is prepared by spreading a slurry of MnO2, carbon black, graphite fibers, PVDF in DMA. A 1M Na2SO4 solution impregnated in the porous paper separator (Nippon Kodoshi Corportion, Japan) and a polymer electrolyte membrane (Nafion 115) have been employed as electrolytes. The different supercapacitors were electrochemically characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (G–CD), electrochemical impedance spectroscopy (EIS) and long-term cycling stability tests. The hybrid carbon-based textile supercapacitors exhibited capacitance performance of 137 and 120 F/g with the porous separator and Nafion 115 membrane, respectively. Specially, the solid-state (Nafion membrane) hybrid device demonstrated very long stability in cycling (10000 cycles) and holding voltage condition at 1.6 V (more than 200 h). Besides, these textile-based capacitors also showed really slow self-discharge.info:eu-repo/semantics/publishedVersio

Carbon and MnO₂ materials on carbon nanofibers cotton textile substrate for hybrid solid-state supercapacitors

This work is focused on the design and development of hybrid solid-state energy storage devices with high capacitive performance. In particular, the work includes, the preparation of carbon composite electrodes based on a carbon nanofibers (CNF) supported on a cotton fabric. The coating of CNF to the cotton cloth is obtained by the dip and dry method. On these so-obtained composite substrates, further layers of activated carbon (Norit A Supra Eur) and manganese oxide (MnO2) material have been subsequenlty deposited to enhance the electrochemical performances of negative and positive electrodes, respectively. The preparation of carbon-based active layers comprises the spreading on the negative CNF-substrate of a slurry containing the activated carbon (AC) material, graphite fibres and polyvinylidene difluoride (PVDF) in N,N dimethylacetamide (DMA). Whereas the positive electrode is prepared by spreading a slurry of MnO2, carbon black, graphite fibers, PVDF in DMA. A 1M Na2SO4 solution impregnated in the porous paper separator (Nippon Kodoshi Corportion, Japan) and a polymer electrolyte membrane (Nafion 115) have been employed as electrolytes. The different supercapacitors were electrochemically characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (G–CD), electrochemical impedance spectroscopy (EIS) and long-term cycling stability tests. The hybrid carbon-based textile supercapacitors exhibited capacitance performance of 137 and 120 F/g with the porous separator and Nafion 115 membrane, respectively. Specially, the solid-state (Nafion membrane) hybrid device demonstrated very long stability in cycling (10000 cycles) and holding voltage condition at 1.6 V (more than 100 h). Besides, these textile-based capacitors also showed slow self-discharge.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) that conceded a Short Term Scientific Mission (STSM) at CNR-ITAE of Messina.info:eu-repo/semantics/publishedVersio

Proteasas de bromeliaceae: I. Estudio preliminar de la fracción proteolíticamente activa presente en frutos de Bromelia laciniosa Mart.

Proteolitically active preparations obtained from matute fruits of Brornelia Iaciniosa Mart. were analyzed by molecular sieve chromatography (Sephadex G-75, Superhe). Best resolution and higher activity are achieved by direct trituration of fruits with cold acetone. Proteolytic capacity is notably diminished in case of unripe fruits.Preparaciones proteolíticamente activas obtenidas a partir de frutos maduros de Bromelia laciniosa Mart fueron anaíizadas por cromatografía de exdusión molecular (Sephadex G75, superfme). El procedimiento de triturar los frutos con acetona fría es el que permite obtener la mejor resolución y los valores más altos de actividad enzirnática. La capacidad proteolitica es considerablemente menor en el caso de frutos verdes

Proteasas de Bromeliaceae: V. Separación y purificación de sulfhidril - proteasas presentes en frutos de Bromelia balaasae Mez

Almost mature fruits of Bromelia serra Griseb., blade homogenized (Waring blender) with cold acetone (-20ºC), provide a light, proteolitically active acetone powder (1, 93g%, w/w). Extractives obtained by gentle stirring with phosphate buffer pH 6,4 containing 5 mM cysteine and 5 mM EDTA (protein content 8, 24 g per 100 g of powder) show good thermal stability at moderates temperatures and highest caseinolytic activity at pH 6.0-7.8. Gel- filtration (Sephadex G-75, Superfine) allows to separate one active fraction which is resolved in two new, more pursed fractions through ion-exchange chromatography (DEAE Sephacel and CM Sepharose).Por trituración de frutos semimaduros de Brormlia serra Griseb. (Bromeliaceae) en presencia de acetona fría (-20ºC) se obtiene un polvo acetónico (1, 93g%, p/p) con actividad proteolítica. La extracción del mismo con buffer fosfatos de pH 6, 4 conteniendo EDTA 5 mM y cisteína 5 mM permite preparar una solución de enzima cruda con un contenido proteico de 8, 24 g por 100 g de polvo, dotada de buena estabilidad térmica a temperaturas moderadas y con un máximo de actividad caseinolítica a pH 6,0-7,8. Esta preparación cruda se purifica por cromatografía de exclusión molecular (Sephadex G-75 Superfine) y la fracción activa se resuelve en dos nuevas fracciones por cromatografía de intercambio iónico (DEAE Sephacel y CM Sepharose)

Proteasas de Bromeliaceae: V. Separación y purificación de sulfhidril - proteasas presentes en frutos de Bromelia balaasae Mez

Almost ripe fruits of Bromelia balansae Mez (Bromeliaceae) were blade homogeneized within cold (-20 O C ) acetone, providing a crude preparation that could be partialiy solubllized in phosphate buffer (pH 6,4) containing EDTA and cysteine 5 mM. Solutions hydrolize casein (maximum a c t ~ t ypH 6.25-8.5O), the activity being enhanced by addition of cysteine. The crude enzyme was purified by molecular sieve chromatography (Sephadex G-75, Superfme) and ion exchange chromatography (DEAE- and CM-Sepharose). Three proteolitically active fractions were thus obtainedLa trituración de frutos semimaduros de Bromelia balansae Mez (Bromeliaceae) en presencia de acetona fría (-20 OC) permite obtener una preparación enzimática cruda, que al ser tratada con buffer fosfatos de pH 6,4 conteniendo EDTA y cisteína 5 mM produce una solución con actividad proteolítica apreciable y con máxima acción hidrolítica sobre caseína dentro de un rango de pH entre 6,25 y 8,50. Esta solución enzimática cruda se purificó por cromatografía de exclusión molecular (Sephadex G-75 Superfuio) y de intercambio iónico (DEAE- y CM-Sepharosa), con lo que se obtuvieron tres fracciones proteolíticamente activas.El presente trabajo recibió el apoyo de la CIC y fue presentado en el X Congreso\nFarmacéutico Argentino (San Luis, 1988)