Aqueous Zn‐ion batteries (AZIBs) have been recognized as promising energy storage devices due to their high theoretical energy density and cost‐effectiveness. However, side reactions and Zn dendrite ...generation during cycling limit their practical application. Herein, ammonium acetate (CH3COONH4) is selected as a trifunctional electrolyte additive to enhance the electrochemical performance of AZIBs. Research findings show that NH4+ (oxygen ligand) and CH3COO– (hydrogenligand) with preferential adsorption on the Zn electrode surface can not only hinder Zn anode directly contact with active H2O, but also regulate the pH value of the electrolyte, thus suppressing the parasitic reactions. Additionally, the formed SEI is mainly consisted of Zn5(CO3)2(OH)6 with a high Zn2+ transference number, which could achieve a dendrite‐free Zn anode by homogenizing Zn deposition. Consequently, the Zn||Zn symmetric batteries with CH3COONH4‐based electrolyte can operate steadily at an ultrahigh current density of 40 mA cm–2 with a cumulative capacity of 6880 mAh cm–2, especially stable cycling at −10 °C. The assembled Zn||MnO2 full cell and Zn||activated carbon capacitor also deliver prominent electrochemical reversibility. This work provides unique understanding of designing multi‐functional electrolyte additive and promotes a long lifespan at ultrahigh current density for AZIBs.
Zn metal anode enabled by CH3COONH4 electrolyte additive for dendrite‐free embraced extraordinary rate‐performance and high reversibility with a cumulative capacity of 6880 mAh cm–2 at an ultrahigh current density of 40 mA cm–2, superior to other Zn anode. The Zn||Zn symmetrical cells with attractive cycling performance stabilize over 900 h at a low temperature of −10 °C.
Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase “secondary mitochondrial ...diseases” essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.
Tea (
Camellia sinensis
) flowers are normally white, even though the leaves could be purple. We previously discovered a specific variety with purple leaves and flowers. In the face of such a ...phenomenon, researchers usually focus on the mechanism of color formation but ignore the change of aroma. The purple tea flowers contain more anthocyanins, which belong to flavonoids. Meanwhile, phenylalanine (Phe), derived from the shikimate pathway, is a precursor for both flavonoids and volatile benzenoid–phenylpropanoids (BPs). Thus, it is not clear whether the BP aroma was attenuated for the appearance of purple color. In this study, we integrated metabolome and transcriptome of petals of two tea varieties, namely, Zijuan (ZJ) with white flowers and Baitang (BT) with purple flowers, to reveal the relationship between color (anthocyanins) and aroma (volatile BPs). The results indicated that in purple petals, the upstream shikimate pathway promoted for 3-deoxy-
D
-arabino-heptulosonate 7-phosphate synthase (DAHPS) was elevated. Among the increased anthocyanins, delphinidin-3-
O
-glucoside (DpG) was extremely higher; volatile BPs, including benzyl aldehyde, benzyl alcohol, acetophenone (AP), 1-phenylethanol, and 2-phenylethanol, were also enhanced, and AP was largely elevated. The structural genes related to the biosynthesis of volatile BPs were induced, while the whole flavonoid biosynthesis pathway was downregulated, except for the genes
flavonoid 3′-hydroxylase
(
F3′H
) and
flavonoid 3′,5′-hydroxylase
(
F3′5′H
), which were highly expressed to shift the carbon flux to delphinidin, which was then conjugated to glucoside by increased bronze-1 (BZ1) (UDP-glucose: flavonoid 3-
O
-glucosyltransferase) to form DpG. Transcription factors (TFs) highly related to AP and DpG were selected to investigate their correlation with the differentially expressed structural genes. TFs, such as MYB, AP2/ERF, bZIP, TCP, and GATA, were dramatically expressed and focused on the regulation of genes in the upstream synthesis of Phe (
DAHPS
;
arogenate dehydratase/prephenate
dehydratase
) and the synthesis of AP (
phenylacetaldehyde reductase
;
short-chain dehydrogenase/reductase
), Dp (
F3′H
;
F3′5′H
), and DpG (
BZ1
), but inhibited the formation of flavones (
flavonol synthase
) and catechins (
leucoanthocyanidin reductase
). These results discovered an unexpected promotion of volatile BPs in purple tea flowers and extended our understanding of the relationship between the BP-type color and aroma in the tea plant.
Green chemistry aims at developing reactions that are cheap, clean and use less energy. For that, multicomponent reactions are drawing attention, yet, actual methods involve complicated work-ups, ...hazardous solvents, toxic catalysts, high catalyst loads, harsh reaction conditions and tedious catalyst preparation. Here, we demonstrate that the commercially available reagent, 9-mesityl-10 methylacridinium perchlorate (Acr
+
-Mes ClO
4
−
), can serve as a photocatalyst in the presence of a blue lamp light source, promoting the synthesis of 2-amino-4H-chromenes via a multicomponent reaction with low catalyst loadings. A wide range of aromatic aldehydes readily undergo condensation with malononitrile and ArOH-type structural motifs under mild conditions to afford the products in 76–95% yield within 60 min.
Leaf color is one of the key factors involved in determining the processing suitability of tea. It relates to differential accumulation of flavor compounds due to the different metabolic mechanisms. ...In recent years, photosensitive etiolation or albefaction is an interesting direction in tea research field. However, the molecular mechanism of color formation remains unclear since albino or etiolated mutants have different genetic backgrounds. In this study, wide-target metabolomic and transcriptomic analyses were used to reveal the biological mechanism of leaf etiolation for 'Huangyu', a bud mutant of 'Yinghong 9'. The results indicated that the reduction in the content of chlorophyll and the ratio of chlorophyll to carotenoids might be the biochemical reasons for the etiolation of 'Huangyu' tea leaves, while the content of zeaxanthin was significantly higher. The differentially expressed genes (DEGs) involved in chlorophyll and chloroplast biogenesis were the biomolecular reasons for the formation of green or yellow color in tea leaves. In addition, our results also revealed that the changes of DEGs involved in light-induced proteins and circadian rhythm promoted the adaptation of etiolated tea leaves to light stress. Variant colors of tea leaves indicated different directions in metabolic flux and accumulation of flavor compounds.
"Yinghong 9" is a widely cultivated large-leaf variety in South China, and the black tea made from it has a high aroma and strong sweet flavor. "Huangyu" is a light-sensitive tea variety with yellow ...leaves. It was cultivated from the bud-mutation of "Yinghong 9" and has a very low level of chlorophyll during young shoot development. Due to chlorophyll being involved in carbon fixation and assimilation, the changes in photosynthesis might potentially affect the accumulation of flavor metabolites, as well as the quality of "Huangyu" tea. Although "Huangyu" has a golden yellow color and high amino acid content, the mechanism underlying the formation of leaf color and drinking value remains unclear. The widely targeted metabolomics and GC-MS analysis were performed to reveal the differences of key metabolites in fresh and fermented leaves between "Yinghong 9" and "Huangyu." The results showed that tea polyphenols, total chlorophyll, and carotenoids were more abundant in "Yinghong 9." Targeted metabolomics analysis indicated that kaempferol-3-glycoside was more abundant in "Yinghong 9," while "Huangyu" had a higher ratio of kaempferol-3-glucoside to kaempferol-3-galactoside. Compared with "Yinghong 9" fresh leaves, the contents of zeaxanthin and zeaxanthin palmitate were significantly higher in "Huangyu." The contents of α-farnesene, β-cyclocitral, nerolidol, and
geranylacetone, which were from carotenoid degradation and involved in flowery-fruity-like flavor in "Huangyu" fermented leaves, were higher than those of "Yinghong 9." Our results indicated that "Huangyu" was suitable for manufacturing non-fermented tea because of its yellow leaf and flowery-fruity-like compounds from carotenoid degradation.
Developing electrodes with long lifespan and wide-temperature adaptability is crucial important to achieve high-performance sodium/potassium-ion batteries (SIBs/PIBs). Herein, the SnSe2-SePAN ...composite was fabricated for extraordinarily stable and wide-temperature range SIBs/PIBs through a coupling strategy between controllable electrospinning and selenylation, in which SnSe2 nanoparticles were uniformly encapsulated in the SePAN matrix. The unique structure of SnSe2-SePAN not only relieves drastic volume variation but also guarantees the structural integrity of the composite, endowing SnSe2-SePAN with excellent sodium/potassium storage properties. Consequently, SnSe2-SePAN displays a high sodium storage capacity and excellent feasibility in a wide working temperature range (−15 to 60°C: 300 mAh g−1/700 cycles/−15°C; 352 mAh g−1/100 cycles/60°C at 0.5 A g−1). At room temperature, it delivers a record-ultralong cycling life of 192 mAh g−1 that exceeds 66 000 cycles even at 15 A g−1. It exhibits extremely superb electrochemical performance in PIBs (157 mAh g−1 exceeding 15 000 cycles at 5 A g−1). The ex situ XRD and TEM results attest the conversion-alloy mechanism of SnSe2-SePAN. Also, computational calculations verify that SePAN takes an important role in intensifying the electrochemical performance of SnSe2-SePAN electrode. Therefore, this study breaks new ground on solving the polyselenide dissolution issue and improving the wide temperature workable performance of sodium/potassium storage.
Green chemistry is developing to invent new reactions that are cheaper, cleaner and use less energy. Acetalization is a common strategy for the protection of aldehydes in synthetic chemistry, yet ...actual protocols of acetals synthesis are limited by difficult workups, the use of high-loading catalyst, harsh reaction conditions, and catalyst tedious preparation. Alternatively, photocatalysis allows to access functional products with minimum synthetic procedures and waste generation. Here we use sodium 4-6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-ylbenzene-1,3-disulfonate (acid red 52) as photocatalyst under yellow light irradiation. We obtained a wide array of acyclic and cyclic acetals in 75–93% yields. Results show the efficient acetalization of aldehydes with alcohols at room temperature, the use of abundant and sustainable alcohols as both the solvents and coupling agents, low catalyst loading, short reaction time, and readily available catalyst, which might be applied to green-catalyzed systems.
Aqueous rechargeable batteries are safe and environmentally friendly and can be made at a low cost; as such, they are attracting attention in the field of energy storage. However, the temperature ...sensitivity of aqueous batteries hinders their practical application. The solvent water freezes at low temperatures, and there is a reduction in ionic conductivity, whereas it evaporates rapidly at high temperatures, which causes increased side reactions. This review discusses recent progress in improving the performance of aqueous batteries, mainly with respect to electrolyte engineering and the associated strategies employed to achieve such improvements over a wide temperature domain. The review focuses on five electrolyte engineering (aqueous high-concentration electrolytes, organic electrolytes, quasi-solid/solid electrolytes, hybrid electrolytes, and eutectic electrolytes) and investigates the mechanisms involved in reducing the solidification point and boiling point of the electrolyte and enhancing the extreme-temperature electrochemical performance. Finally, the prospect of further improving the wide temperature range performance of aqueous rechargeable batteries is presented.
Display omitted
We have developed a practical approach for divergent synthesis of aryl α,α-difluoroarylketones under mild conditions. Mechanistic investigations via DFT calculations indicates that ...the products are formed via electrophilic fluorination.
Here, we report a facile approach for divergent synthesis of aryl α,α-difluoroketones from both terminal and internal arylalkynes by employing Selectfluor as the fluorine-source. DFT calculations of this transformation reveal that the products are formed via electrophilic fluorination of the CC triple bond. In comparison with the existed approaches allowing the preparation of limited α,α-difluoroketones, the present work enriches the capabilities of synthesizing different α-fluorinated arylketones, and offers a fundamental basis for further development of fluorinated products including drugs and functional materials due to the significant importance of fluorinated ketones in organic synthesis. Moreover, the metal-free conditions in conjunction with the use of cost-effective H2O and better functional group tolerance highlight the practicality of the developed chemistry.
PDF
