Hybrid redox flow cells with enhanced electrochemical performance via binderless and electrophoretically deposited nitrogen-doped graphene on carbon paper electrodes.

Hybrid redox flow cells (HRFC) are key enablers for the development of reliable large-scale energy storage systems; however, their high cost, limited cycle performance, and incompatibilities associated with the commonly used carbon-based electrodes undermine HRFC's commercial viability. While this is often linked to lack of suitable electrocatalytic materials capable of coping with HRFC electrode processes, the combinatory use of nanocarbon additives and carbon paper electrodes holds new promise. Here, by coupling electrophoretically deposited nitrogen-doped graphene (N-G) with carbon electrodes, their surprisingly beneficial effects on three types of HRFCs, namely, hydrogen/vanadium (RHVFC), hydrogen/manganese (RHMnFC), and polysulfide/air (S-Air), are revealed. RHVFCs offer efficiencies over 70% at a current density of 150 mA cm-2 and an energy density of 45 Wh L-1 at 50 mA cm-2, while RHMnFCs achieve a 30% increase in energy efficiency (at 100 mA cm-2). The S-Air cell records an exchange current density of 4.4 × 10-2 mA cm-2, a 3-fold improvement of kinetics compared to the bare carbon paper electrode. We also present cost of storage at system level compared to the standard all-vanadium redox flow batteries. These figures-of-merit can incentivize the design, optimization, and adoption of high-performance HRFCs for successful grid-scale or renewable energy storage market penetration

Mechanistic Studies of the Water–Gas Shift Reaction over Pt/Ce_<i>x</i>Zr_1–<i>x</i>O₂ Catalysts: The Effect of Pt Particle Size and Zr Dopant

A series of <i>y</i> wt % Pt/Ce_<i>x</i>Zr_1–<i>x</i>O₂ catalysts (<i>y</i> = 0.1, 0.5, and 1.0; <i>x</i> = 0.3, 0.5, and 0.7) were synthesized and characterized to investigate the effect of CeO₂ doping with Zr⁴⁺ and of Pt particle size (Pt/Ce_0.5Zr_0.5O₂) on important mechanistic and kinetic aspects of the water–gas shift (WGS) reaction. These included the concentration (μmol·g^–1 or θ (surface coverage based on Pt_s)) and chemical structure of <i>active</i> reaction intermediates present in the “carbon path” and “hydrogen path” of the WGS reaction in the 200–300 °C range and the prevailing mechanism among “redox” and “associative formate” largely considered in the literature. Toward this goal, steady-state isotopic transient kinetic analysis coupled with in situ DRIFTS and mass spectrometry experiments were performed for the first time using D₂O and ¹³CO isotopic gases. A novel transient isotopic experiment allowed quantification of the initial transient rate of reaction of adsorbed formate (HCOO−) with water and that of adsorbed CO with water under steady-state WGS reaction conditions. On the basis of these results, it was concluded that formate should not be considered as an important intermediate. It was found that on Pt/Ce_<i>x</i>Zr_1–<i>x</i>O₂ catalysts, the WGS reaction mechanism switches from “redox” to a combination of “redox” and “associative formate with −OH group regeneration” mechanisms by increasing the reaction temperature from 200 to 300 °C. The superior WGS activity exhibited by Pt/Ce_<i>x</i>Zr_1–<i>x</i>O₂ (<i>x</i> = 0.3, 0.5, and 0.7) catalysts in comparison with Pt/CeO₂ was explained by the fact that the site reactivity of Pt across the metal–support interface was increased as a consequence of the introduction of Zr⁴⁺ into the ceria lattice. The concentration of <i>active</i> reaction intermediates was found to strongly depend on reaction temperature, support composition (Ce/Zr ratio), and Pt particle size, parameters that all determine the shape of the light-off CO-conversion curve

Capture Fisheries and Aquaculture Exploitation in the Aegean Sea Archipelago

The Aegean Sea is an insular archipelago in North Mediterranean Sea. It exhibits 60 inhabited islands, more than 1,400 small islands and more than 2,500 outcrops and rocks. Its total area is in excess of 215,000 km2. Fisheries and aquaculture are the second most important economic activities after tourism, from the point of view of contribution to the national GDP. However, as segments of the primary production, they are more important than tourism for job and income security of the numerous rural fishery-dependent communities in the region, as tourism activity is limited in certain areas and islands. The fishing fleet in the Aegean Sea amounts to 11,580 vessels approximately from which 95% belongs to the smallscale fishery segment and operates from over 100 ports, harbours and fishing refuges on the mainland and the islands. Fisheries production reached almost 69,000 t in 2018. Aquaculture in Greece is a fast developing industry with export orientation. The total national aquaculture production today amounts to 133,000 t of sea bass and sea bream for 2016, compared to 400 t in 1984. Aquaculture production in the Aegean Sea amounts to 83,000 t (63% of total) and fetching approximately 370 million €. From the economic point of view, the fisheries sector in the Aegean Sea faces many challenges. Even though demand for high-quality fishery products is stable and increasing, mainly due to tourism, the market structure is such that net income margins for capture fisheries are low between 8 and 12% at the producer level. Aquaculture suffers from very low prices close or seasonally below production cost levels due to the market competition of aquaculture production of the same species (whole, fresh or chilled sea bass and sea bream) by most Mediterranean States. Finally, fishery product processing industry faces drops in the demand of traditional products in the region (canned in oil, smoked) and low market prices for other types of products (fillets, frozen, etc.) which has forced many companies to diverse their production to vegetables and other local high-market value produce. © Springer Nature Switzerland AG 202

The 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot

The human fetal globin genes consist of the first mammalian genomic loci for which gene conversion was reported. To date, 14 gene conversions have been described in the human Gγ- and Aγ-globin genes, the vast majority of which are restricted to the coding sequences. Here, we provide evidence for three new gene conversion events in the 5′ regulatory region of the human fetal globin genes, identified during a large genetic screening effort in adult individuals with high fetal hemoglobin (Hb) levels. The sequence variations, resulting from these conversion events, are transcriptionally silent polymorphisms that do not contribute to increased fetal Hb levels. Our results suggest that the 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot that prevent globin gene promoter sequence diversification, further underlining the need for two functional fetal globin genes in fetal erythropoiesis. Copyright © Informa Healthcare USA, Inc

The 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot

The human fetal globin genes consist of the first mammalian genomic loci for which gene conversion was reported. To date, 14 gene conversions have been described in the human Gγ- and Aγ-globin genes, the vast majority of which are restricted to the coding sequences. Here, we provide evidence for three new gene conversion events in the 5′ regulatory region of the human fetal globin genes, identified during a large genetic screening effort in adult individuals with high fetal hemoglobin (Hb) levels. The sequence variations, resulting from these conversion events, are transcriptionally silent polymorphisms that do not contribute to increased fetal Hb levels. Our results suggest that the 5′ regulatory region of the human fetal globin genes is a gene conversion hotspot that prevent globin gene promoter sequence diversification, further underlining the need for two functional fetal globin genes in fetal erythropoiesis. Copyright © Informa Healthcare USA, Inc