A neutral-pH aqueous redox flow battery based on sustainable organic electrolytes

Aqueous organic redox flow batteries (AORFBs) have gained increasing attention for large-scale storage due to the advantages of decoupled energy and power, safe and sustainable chemistry, and tunability of the redox-active species. Here, we report the development of a neutral-pH AORFB assembled with a highly water-soluble ferrocene 1,1-disulfonic disodium salt (DS−Fc) and two viologen derivatives, 1,1’-bis(3-sulfonatopropyl)-viologen (BSP−Vi) and Bis(3-trimethylammonium)propyl viologen tetrachloride (BTMAP−Vi). Synthesized electrolytes showed excellent redox potential, good diffusion coefficient, and a good transfer rate constant. In particular, BSP−Vi has a more negative redox potential (-0.4 V) than BTMAP−Vi (−0.3 V) and faster kinetics; therefore, it was selected to be assembled in an AORFB as anolyte, coupled with DS−Fc as catholyte.The resulting AORFB based on BTMAP−Vi/DS−Fc and BSP−Vi/DS−Fc redox couple had a high cell voltage (1.2 V and 1.3 V, respectively) and theoretical energy density (13 WhL−1 and 14 WhL−1 respectively) and was able to sustain 70 charge-discharge cycles with energy efficiency as high as 97 %

Desempenho de dois híbridos de eucalipto no sistema de ILPF no noroeste paulista.

A integração lavoura-pecuária-floresta (ILPF) consiste de diferentes sistemas produtivos de grãos, fibras, madeira, carne, leite e agroenergia, implantados na mesma área, em consórcio, em rotação ou em sucessão, envolvendo o plantio, principalmente, de grãos e a implantação ou recuperação de pastagens. O presente trabalho teve por objetivo avaliar o desempenho de dois híbridos de eucalipto: Grancam 1277 (Eucalyptus grandis x Eucalyptus camaldulensis) e Urograndis H-13 (Eucalyptus urophila x Eucalyptus grandis), sob o sistema de integração lavoura-pecuária-floresta (ILPF), na região Noroeste Paulista. O experimento foi realizado em Votuporanga, SP, com delineamento experimental inteiramente casualizado, com quatro repetições, em uma área com pastagem degradada, implantada há dez anos, de aproximadamente 10 ha. Concluiu-se que o híbrido Grancam 1277 apresentou maior desenvolvimento em altura, na fase inicial, e maior diâmetro após 414 dias do plantio

Chemical composition and energy yield of elephant-grass biomass as function of five different production ages.

Abstract Elephant grass has high biomass production, with qualities suitable for conversion into bioenergy, but has long been used exclusively for animal feed and only in recent years has it become an energetic alternative. Therefore, it is necessary to select genotypes with potential for energy production. This study evaluated the effect of five harvest times (8, 12, 16, 20, and 24 weeks) on the yield and chemical composition related to biomass quality through combined polynomial regression analyses of the following elephant grass genotypes: Cubano Pinda, Mercker 86-México, Pusa Napier n°1, Mole de Volta Grande, P-241-Piracicaba, and King Grass. A completely randomized design with three replicates, in a split-plot arrangement, was adopted, including two factors (plots = genotypes, subplots = harvest times). The evaluated variables were whole-plant dry matter yield, in t ha-1 (DMY), percentage of neutral detergent fiber (%NDF), and percentage of acid detergent fiber (%ADF). The elephant-grass genotypes Cubano de Pinda, Mercker 86-México, and P-241-Piracicaba showed a linear first-degree effect as a function of the harvest intervals, indicating that they did not reach their maximum production potential. Genotypes Pusa Napier n°1, Mole de Volta Grande, and King Grass, in turn, had a linear second-degree effect. For the NDF variable, all genotypes showed a significant linear second-degree effect as a function of the harvest intervals, except P-241-Piracicaba, for which no regression was observed. For this genotype, there was a significant linear first-degree effect on the %ADF variable

Porous iron-nitrogen-carbon electrocatalysts for anion exchange membrane fuel cells (AEMFC)

High-performance platinum group metal-free (PGM-free) electrocatalysts were prepared from porous organic polymers (POPs) precursors with highly-porous structures and adjustable surface area. A resin phenol-melamine-based POP and an iron salt were used to synthesize Fe−N−C catalysts with different iron contents (0.2–1.3 wt.%). Electrochemical and spectroscopical characterization allowed us to elucidate the effect of Fe content on the material's structure, surface chemistry, and electrocatalytic activity toward the oxygen reduction reaction (ORR). The increase of iron content led to a specific surface area decrease, preserving the morphological structure, with the formation of highly-active catalytic sites, as indicated by X-ray photoelectron spectroscopy (XPS) analysis. The rotating ring disk electrode experiments, performed at pH=13, confirmed the high ORR activity of both 0.5 Fe (E1/2=0.84 V) and 1.3 Fe (E1/2=0.83 V) catalysts, which were assembled at the cathode of a H2-fed anion exchange membrane fuel cells (AEMFC) equipped with a FAA-3-50 membrane, evidencing promising performance (0.5 Fe, maximum power density, Max PD=69 mA cm−2 and 1.3 Fe, Max PD=87 mA cm−2) with further advancement prospects

Confirming the lattice contraction in CdSe nanocrystals grown in a glass matrix by Raman scattering

This work gives the evidence of the lattice contraction in CdSe nanocrystals (NCs) grown in a glass matrix. The CdSe NCs were investigated by atomic forcemicroscopy (AFM), optical absorption (OA), and Raman spectroscopy. The average size of CdSe NCs can be estimated by AFM images. Using the OA spectra and the effective-mass approximation, it was also possible to estimate the average sizes of CdSe NCs, which agree very well with the AFM data. These results showed that the CdSe NCs grow with increasing time of heat treatment. The blue shift of the longitudinal optical (LO)modes and surface optical (SO) phononmodes with an increase in the average radius of the NCs, shown in the Raman spectra, was explained by the lattice contraction in CdSe NCs caused by thermodynamic interactions at the interface with the host glass matrix.FAPEMIGMCT/CNP

Streamlined approaches for image classification using principal component analysis and hierarchical clustering of extrudates from coffee and sorghum blends.

This article describes simple methods to group images including principal component analysis (PCA) and hierarchical clustering of principal components (HCPC). Images of expanded and low expanded extrudates were processed using two optimization alternatives: a) image size reduction (from 2126 to 25 pixels); and b) grayscale conversion before size reduction. After applying PCA and HCPC, all tests yielded consistently similar results with the same PCA distribution and identical HCPC groups. Furthermore, expanded and low expanded extrudates formed groups with their respective peers. The RAM allocated to images and the time required to process them was reduced from 1727 Mb to less than 5 Mb and from ~ 2000s to just 0.1s, respectively. These results demonstrate the e feasibility of using these two simple multivariate statistical techniques for image classification

Alto teor de cobre no solo interfere no desempenho produtivo de videiras jovens?

O objetivo deste trabalho foi analisar a interferência dos níveis de cobre no solo nas diferentes partes de videiras jovens cultivadas em solos oriundos de vinhedos em produção