Engineering Redox Flow Battery Electrodes with Spatially Varying Porosity Using Non-Solvent-Induced Phase Separation

Redox flow batteries (RFBs) are a promising electrochemical platform for efficiently and reliably delivering electricity to the grid. Within the RFB, porous carbonaceous electrodes facilitate electrochemical reactions and distribute the flowing electrolyte. Tailoring electrode microstructure and surface area can improve RFB performance, lowering costs. Electrodes with spatially varying porosity may increase electrode utilization and provide surface area in reaction-limited zones; however, the efficacy of such designs remains an open area of research. Herein, a non-solvent-induced phase-separation (NIPS) technique that enables the reproducible synthesis of macrovoid-free electrodes with well-defined across-thickness porosity gradients is described. The monotonically varying porosity profile is quantified and the physical properties and surface chemistries of porosity-gradient electrodes are compared with macrovoid-containing electrode, also synthesized by NIPS. Then, the electrochemical and fluid dynamic performance of the porosity-gradient electrodes is evaluated, exploring the effect of changing the direction of the porosity gradient and benchmarking against the macrovoid-containing electrode. Lastly, the performance is examined in a vanadium RFB, finding that the porosity-gradient electrode outperforms the macrovoid electrode, is independent of gradient direction, and performs favorably compared to advanced electrodes in the contemporary literature. It is anticipated that the approach motivates further exploration of microstructurally tailored electrodes in electrochemical systems.</p

Race, resistance and translation: the case of John Buchan’s UPrester John

In postcolonial translation studies, increasing attention is being given to the asymmetrical relationships between dominant and indigenous languages. This paper argues that John Francis Cele’s UPrester John (1958), is not simply a subordinated and obeisant translation of John Buchan’s adventure thriller Prester John (1910), but a more complex form of textuality that is both oppositional and complicit with the workings of apartheid. Although Cele’s translation reproduces Buchan’s story of a daring young Scotsman who single-handedly quells a black nationalist uprising, it also ameliorates the novel’s racist language and assumption. Cele’s translation practice is examined in the context of apartheid publishing and Bantu education.Web of Scienc

Disrupted Membrane Structure and Intracellular Ca2+ Signaling in Adult Skeletal Muscle with Acute Knockdown of Bin1

Efficient intracellular Ca2+ ([Ca2+]i) homeostasis in skeletal muscle requires intact triad junctional complexes comprised of t-tubule invaginations of plasma membrane and terminal cisternae of sarcoplasmic reticulum. Bin1 consists of a specialized BAR domain that is associated with t-tubule development in skeletal muscle and involved in tethering the dihydropyridine receptors (DHPR) to the t-tubule. Here, we show that Bin1 is important for Ca2+ homeostasis in adult skeletal muscle. Since systemic ablation of Bin1 in mice results in postnatal lethality, in vivo electroporation mediated transfection method was used to deliver RFP-tagged plasmid that produced short –hairpin (sh)RNA targeting Bin1 (shRNA-Bin1) to study the effect of Bin1 knockdown in adult mouse FDB skeletal muscle. Upon confirming the reduction of endogenous Bin1 expression, we showed that shRNA-Bin1 muscle displayed swollen t-tubule structures, indicating that Bin1 is required for the maintenance of intact membrane structure in adult skeletal muscle. Reduced Bin1 expression led to disruption of t-tubule structure that was linked with alterations to intracellular Ca2+ release. Voltage-induced Ca2+ released in isolated single muscle fibers of shRNA-Bin1 showed that both the mean amplitude of Ca2+ current and SR Ca2+ transient were reduced when compared to the shRNA-control, indicating compromised coupling between DHPR and ryanodine receptor 1. The mean frequency of osmotic stress induced Ca2+ sparks was reduced in shRNA-Bin1, indicating compromised DHPR activation. ShRNA-Bin1 fibers also displayed reduced Ca2+ sparks' amplitude that was attributed to decreased total Ca2+ stores in the shRNA-Bin1 fibers. Human mutation of Bin1 is associated with centronuclear myopathy and SH3 domain of Bin1 is important for sarcomeric protein organization in skeletal muscle. Our study showing the importance of Bin1 in the maintenance of intact t-tubule structure and ([Ca2+]i) homeostasis in adult skeletal muscle could provide mechanistic insight on the potential role of Bin1 in skeletal muscle contractility and pathology of myopathy

Insect repellent and chemical agronomic treatments to reduce seed numberin'Afourer'mandarin. Effect on yield and fruit diameter

Obtaining citrus fruits without seeds is a recurrent objective for farmers as it is one of the most valued char-acteristics, especially in mandarins.'Afourer'tangor is a highly valuable well-established mandarin, and a highpercentage of seeded fruits are produced under cross-pollination conditions. Several agronomic techniques havebeen suggested to control presence of seeds, such as covering with nets and copper sulfate (CuSO4) and gib-berellic acid (GA3) treatments. Natural bee repellents are also proposed to reduce the number of seeds per fruit.In this study, we aimed to compare the effect of several agronomic treatments to reduce the seed number in'Afourer' mandarin. To this end, we assessed the effect of chemical and bee repellent treatments on the seednumber per fruit and the side effect on yield and fruit diameter. Under these experimental conditions the two beerepellents, one based on zinc and one based onCapsicum annuum, were not useful for reducing the seed numberper fruit in'Afourer'mandarin. The copper sulfate + GA3treatment reduced the seed number per fruit by only35%, and this efficiency was clearly not enough to reduce the seed number for commercial purposes. The mosteffective method to reduce the seed number per fruit was covering with nets, but this technique led to markedlyreduced yields. Yield data was highly variable. Fruit diameter correlated positively with the seed number, but itwas a weak relationship as the seed number explained only 15% of fruit size variability (R2= 0,15)

Development of membrane diagnostics and novel porous materials for next generation redox flow batteries

Embargo 1 year, pdf open access 21-2-202

Diversity in the trifoliate orange taxon reveals two main genetic groups marked by specific morphological traits and water deficit tolerance properties

International audienceTrifoliate orange (Poncirus trifoliata (L.) Raf.) is a very useful taxon for the citrus industry since this rootstock is immune to the Citrus Tristeza virus and confers cold tolerance. Numerous trifoliate orange varieties exist but little is known regarding their behavioural variability when subjected to abiotic constraints. The diversity of 74 P. trifoliata accessions maintained in the INRA-CIRAD Citrus Germplasm Collection was investigated using simple sequence repeat markers. Two major genetic groups were clearly identified as a few homonyms, intergroup or intra-group hybrids and doubled-chromosome tetraploid forms. The Group 1 phenotype was characterized by larger flowers and leaves and smaller seeds than Group 2. Tetraploid accessions showed larger leaves and heavier seeds than all other diploid accessions, regardless of genetic classification. Eight genotypes belonging to both genetic groups, as well as two hybrids between the two groups, were selected to investigate their water deficit tolerance. Stress was applied by withdrawing irrigation for 4 weeks. Physiological parameters such as leaf stomatal conductance, quantum yield of photosystem II electron transport, soil water potential, leaf osmotic potential and transpiration rate were estimated. Some varieties, such as Rubidoux 0101033, were clearly more tolerant to water deficit than others, such as Pomeroy 0101040 and Pomeroy 0110081. Interestingly, accessions that had the highest soil water potential and were the least affected by stress belonged to genetic Group 2. Conversely, trifoliate oranges of genetic Group 1 were the least tolerant

On the Characterization of Membrane Transport Phenomena and Ion Exchange Capacity for Non-Aqueous Redox Flow Batteries

The development of high-performance membrane materials for non-aqueous redox flow batteries (NAqRFBs) could unlock a milestone towards widespread commercialization of the technology. Understanding of transport phenomena through membrane materials requires diagnostic tools able to monitor the concentrations of redox active species. While membrane characterization in aqueous media focused the attention of the scientific community, dedicated efforts for non-aqueous electrolytes remain poorly developed. Here, we develop new methodologies to assess critical membrane properties, namely ion exchange capacity and species transport, applied to NAqRFBs. In the first part, we introduce a method based on 19F-NMR to quantify ion exchange capacity of membranes with hydrophobic anions commonly used in non-aqueous systems (e.g., PF6− and BF4−). We find a partial utilization of the ion exchange capacity compared to the values reported using traditional aqueous chemistry ions, possibly limiting the performance of NAqRFB systems. In the second part, we study mass transport with a microelectrode placed on the electrolyte tank. We determine TEMPO crossover rates through membranes by using simple calibration curves that relate steady-state currents at the microelectrode with redox active species concentration. Finally, we show the limitations of this approach in concentrated electrolyte systems, which are more representative of industrial flow battery operation