Enabling Long-Life Aqueous Organic Redox Flow Batteries with a Highly Stable, Low Redox Potential Phenazine Anolyte.

Aqueous organic redox flow batteries (AORFBs) are considered a promising energy storage technology due to the sustainability and designability of organic active molecules. Despite this, most of AORFBs suffer from limited stability and low voltage because of the chemical instability and high redox potential of organic molecules in anolyte. Herein, we propose a new phenazine derivative, 4,4'-(phenazine-2,3-diylbis(oxy))dibutyric acid (2,3-O-DBAP), as a water-soluble and chemically stable anodic active molecules. By combining calculations and experiments, we demonstrate that 2,3-O-DBAP exhibits a higher solubility, a lower redox potential (-0.699 V vs SHE), and greater chemical stability than other O-DBAP isomers. Then, we demonstrate a long-lasting flow cell with an average discharge voltage of 1.12 V, a low fade rate of 0.0127%, and a lifespan of 62 days at pH 14 using 2,3-O-DBAP paired with ferri/ferrocyanide. The negligible self-discharge behavior also verifies the high stability of 2,3-O-DBAP. These results highlight the importance of molecular engineering for AORFBs.

A chloroplast protein atlas reveals punctate structures and spatial organization of biosynthetic pathways.

Chloroplasts are eukaryotic photosynthetic organelles that drive the global carbon cycle. Despite their importance, our understanding of their protein composition, function, and spatial organization remains limited. Here, we determined the localizations of 1,034 candidate chloroplast proteins using fluorescent protein tagging in the model alga Chlamydomonas reinhardtii. The localizations provide insights into the functions of poorly characterized proteins; identify novel components of nucleoids, plastoglobules, and the pyrenoid; and reveal widespread protein targeting to multiple compartments. We discovered and further characterized cellular organizational features, including eleven chloroplast punctate structures, cytosolic crescent structures, and unexpected spatial distributions of enzymes within the chloroplast. We also used machine learning to predict the localizations of other nuclear-encoded Chlamydomonas proteins. The strains and localization atlas developed here will serve as a resource to accelerate studies of chloroplast architecture and functions.

Widespread epistasis among beneficial genetic variants revealed by high-throughput genome editing.

The phenotypic effect of any genetic variant can be altered by variation at other genomic loci. Known as epistasis, these genetic interactions shape the genotype-phenotype map of every species, yet their origins remain poorly understood. To investigate this, we employed high-throughput genome editing to measure the fitness effects of 1,826 naturally polymorphic variants in four strains of Saccharomyces cerevisiae. About 31% of variants affect fitness, of which 24% have strain-specific fitness effects indicative of epistasis. We found that beneficial variants are more likely to exhibit genetic interactions and that these interactions can be mediated by specific traits such as flocculation ability. This work suggests that adaptive evolution will often involve trade-offs where a variant is only beneficial in some genetic backgrounds, potentially explaining why many beneficial variants remain polymorphic. In sum, we provide a framework to understand the factors influencing epistasis with single-nucleotide resolution, revealing widespread epistasis among beneficial variants.

Gene-by-environment interactions are pervasive among natural genetic variants.

Gene-by-environment (GxE) interactions, in which a genetic variant's phenotypic effect is condition specific, are fundamental for understanding fitness landscapes and evolution but have been difficult to identify at the single-nucleotide level. Although many condition-specific quantitative trait loci (QTLs) have been mapped, these typically contain numerous inconsequential variants in linkage, precluding understanding of the causal GxE variants. Here, we introduce BARcoded Cas9 retron precise parallel editing via homology (CRISPEY-BAR), a high-throughput precision genome editing strategy, and use it to map GxE interactions of naturally occurring genetic polymorphisms impacting yeast growth. We identified hundreds of GxE variants within condition-specific QTLs, revealing unexpected genetic complexity. Moreover, we found that 93.7% of non-neutral natural variants within ergosterol biosynthesis pathway genes showed GxE interactions, including many impacting antifungal drug resistance through diverse molecular mechanisms. In sum, our results suggest an extremely complex, context-dependent fitness landscape characterized by pervasive GxE interactions while also demonstrating massively parallel genome editing as an effective means for investigating this complexity.

Stable Operation of Aqueous Organic Redox Flow Batteries in Air Atmosphere.

As a green route for large-scale energy storage, aqueous organic redox flow batteries (AORFBs) are attracting extensive attention. However, most of the reported AORFBs were operated in an inert atmosphere. Herein, we clarify this issue by using the reported AORFB (i.e., 3, 3'-(9,10-anthraquinone-diyl)bis(3-methylbutanoicacid) (DPivOHAQ)||Ferrocyanide) as an example. We demonstrate that the dissolved O2 can oxidize the discharged DPivOHAQ in anolyte, leading to capacity-imbalance between anolyte and catholyte. Therefore, this cell shows continuous capacity fading when operated in an air atmosphere. We propose a simple strategy for this challenge, in which the oxygen evolution reaction (OER) in catholyte is employed to balance oxygen reduction reaction (ORR) in anolyte. When using the Ni(OH)2 -modifed carbon felt (CF) as a current collector for catholyte, this cell shows an excellent stability in air atmosphere because the Ni(OH)2 -induced OER capacity in catholyte exactly balances the ORR capacity in anolyte. Such O2 -balance strategy facilitates AORFBs' practical application.

Solvent-free protic liquid enabling batteries operation at an ultra-wide temperature range.

Nowadays, electrolytes for commercial batteries are mostly liquid solutions composed of solvent and salt to migrate the ions. However, solvents of the electrolyte bring several inherent limitations, either the electrochemical window, working temperature, volatility or flammability. Herein, we report polyphosphoric acid as a solvent-free protic liquid electrolyte, which excludes the demerits of solvent and exhibits unprecedented superiorities, including nonflammability, wider electrochemical stability window (>2.5 V) than aqueous electrolyte, low volatility and wide working temperature range (>400 °C). The proton conductive electrolyte enables MoO3/LiVPO4F rocking-chair battery to operate well in a wide temperature range from 0 °C to 250 °C and deliver a high power density of 4975 W kg-1 at a high temperature of 100 °C. The solvent-free electrolyte could provide a viable route for the stable and safe batteries working under harsh conditions, opening up a route towards designing wide-temperature electrolytes.

VPO4 F Fluorophosphates Polyanion Cathodes for High-Voltage Proton Storage.

Proton batteries are emerging in electrochemical energy storage because of the associated fast kinetics, low cost and high safety. However, their development is hindered by the relatively low energy density due to the limited choice of cathode materials. Herein, metal phosphate polyanion cathodes are proposed as the proton cathode for the first time. Combining experimental results and theoretical simulations, a universal criterion for the proton cathode was put forward. Vanadium fluorophosphate (VPO4 F) was demonstrated as a promising high-voltage proton cathode material with a specific capacity of 116 mAh g-1 at a high potential of 1.0 V (vs. SHE). The proton insertion/extraction mechanism in the VPO4 F electrode was also verified through X-ray diffraction (XRD) and photoelectron spectroscopy (XPS). Furthermore, the stability of VPO4 F was investigated in various electrolytes and the optimized electrolyte enabled the stable operation of VPO4 F for 300 cycles. This work provides new inspiration in the exploitation of new electrode materials for electrochemical proton storage devices.

[Quantum efficiency of the 5D0 level of Eu3+ at C2 site in cubic nanocrystalline Y2O3].

In the present the authors are trying to work out how the quantum efficiency depends on the nanocrystalline size. Cubic nanocrystalline Y2O3 : Eu3+ samples were prepared by chemical self-combustion. The bulk Y2O3 : Eu3+ was obtained by annealing the nanocrystalline at 1 000 degrees C for 2 h. The emission spectra, XRD and fluorescence decay showed that the emission intensities are increased and fluorescence decay becomes slow with an increase in particle diameter of the samples. Two routes were used to estimate the quantum efficiency of the 5D0 level of Eu3+ at C2 site. The quantum efficiencies of 5D0 level of Eu3+ at C2 site in the samples depend on the nanocrystalline sizes. Finally, a detailed discussion about these two approaches for estimating the quantum efficiencies was made.

[Synthesis and luminous characteristics of Y (P, V)O4: Eu3+ phosphors for PDP].

Y(P, V)O4 :Eu3+ phosphors with good morphology for plasma display panels have been prepared via coprecipitation reaction. The phosphor was characterized by SEM and photoluminescence under UV (325 nm)and VUV (147 nm) excitation. The emission spectra depending on temperature under 325 nm excitation by laser indicated that there exist energy transfer between VO4(3-) group and Eu3+ ion. Under 147 nm excitation, the most intense emission peaks of commercial (Y,Gd)BO3 :Eu3+ phosphor range around 593 nm, and those of Y(P, V)O4 :Eu3+ phosphors prepared by coprecipitation reaction ranged around 619 nm. The red emission color purity of Y(P, V)O4 :Eu3+ phosphor is much better than that of (Y,Gd)BO3: Eu3+, and its relative emission intensity is almost close to that of the commercial phosphor.