Anion O2 Research Articles

Visualization of Tetrahedral Li in the Alkali Layers of Li-Rich Layered Metal Oxides.

Understanding Li+ ion diffusion pathways in Li-rich layered transition metal (TM) oxides is crucial for understanding the sluggish kinetics in anionic O2- redox. Although Li diffusion within the alkali layers undergoes a low-barrier octahedral-tetrahedral-octahedral pathway, it is less clear how Li diffuses in and out of the TM layers, particularly given the complex structural rearrangements that take place during the oxidation of O2-. Here, we develop simultaneous electron ptychography and annular dark field imaging methods to unlock the Li migration pathways in Li1.2Ni0.13Mn0.54Co0.13O2 associated with structural changes in the charge-discharge cycle. At the end of TM oxidation and before the high-voltage O oxidation plateau, we show that the Li migrating out of the TM layers occupies the alkali-layer tetrahedral sites on opposite sides of the TM layers, forming Li-Li dumbbell configurations, consistent with the density functional theory calculations. Also occurring are the TM migration and phase transition from O3 to O1 stacking, leading to unstable tetrahedral Li and the absence of Li contrast in imaging. Upon further Li deintercalation to 4.8 V, most of the tetrahedral Li are removed. After discharging to 2 V, we did not identify the reformation of tetrahedral Li but observed permanently migrated TMs at the alkali-layer sites, disfavoring the Li occupying the tetrahedral sites for diffusion. Our findings suggest a landscape of Li diffusion pathways in Li-rich layered oxides and strategies for minimizing the disruption of Li diffusion.

Induced Anion Redox before Full Oxidation of Ru4+/Ru5+ through Local Configuration Modulation in P2-Na0.67[Mg0.33Ru0.67]O2

The study of anionic redox in layered-oxide cathodes for Na-ion batteries (NIBs) has been extensive, aiming to attain high-energy density. The involvement of Mn4+ or Ru5+ oxidation states is known to be crucial for the anionic O2 −/O− reaction during Na+ de/intercalation. Nevertheless, our findings indicate that anionic redox can activate in Ru-based layered-oxide cathodes prior to complete Ru4+/Ru5+ oxidation. By employing first-principles calculation and experimental techniques, we disclose that additional Na+ deintercalation from P2-Na0.33[Mg0.33Ru0.67]O2 relies on anionic oxidation after extracting 0.33 mol Na+ from P2-Na0.67[Mg0.33Ru0.67]O2, concomitant with cationic oxidation of Ru4+/Ru4.5+. Specifically, only the oxygen adjacent to 2Mg/1Ru is implicated in anionic redox during Na+ de/intercalation, indicating that the Na–O–Mg arrangement in the P2-Na0.33[Mg0.33Ru0.67]O2 structure significantly reduces the thermodynamic stability of anionic redox compared to cationic redox. Through O anionic and Ru cationic reactions, P2-Na0.67[Mg0.33Ru0.67]O2 demonstrates a substantial specific capacity of ∼172 mA h g− 1 and exceptional power capability, facilitated by facile Na+ diffusion and reversible structural changes during charge/discharge. These findings propose an innovative strategy to enhance anionic redox activity by modifying the local oxygen environment, paving the way for high-energy-density cathode materials in NIBs.

Cofactor-independent C-C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis.

Biosynthesis of atypical angucyclines involves unique oxidative B-ring cleavage and rearrangement reactions, which are catalyzed by AlpJ-family oxygenases, including AlpJ, JadG, and GilOII. Prior investigations established the essential requirement for FADH2/FMNH2 as cofactors when utilizing the quinone intermediate dehydrorabelomycin as a substrate. In this study, we unveil a previously unrecognized facet of these enzymes as cofactor-independent oxygenases when employing the hydroquinone intermediate CR1 as a substrate. The enzymes autonomously drive oxidative ring cleavage and rearrangement reactions of CR1, yielding products identical to those observed in cofactor-dependent reactions of AlpJ-family oxygenases. Furthermore, the AlpJ- and JadG-catalyzed reactions of CR1 could be quenched by superoxide dismutase, supporting a catalytic mechanism wherein the substrate CR1 reductively activates molecular oxygen, generating a substrate radical and the superoxide anion O2 •-. Our findings illuminate a substrate-controlled catalytic mechanism of AlpJ-family oxygenases, expanding the realm of cofactor-independent oxygenases. Notably, AlpJ-family oxygenases stand as a pioneering example of enzymes capable of catalyzing oxidative reactions in either an FADH2/FMNH2-dependent or cofactor-independent manner.

Scavenging of Superoxide Radical Anion by Fluorinated Organosilicon Additives

We have explored a set of structurally related fluorinated and non-fluorinated organosilicon additives and quantified their rates of reaction with the superoxide radical anion O2 •−. using rapid-scan cyclic voltammetry. Absolute reaction rate measurements in acetonitrile solvent show that O2 •− reacts with the fluorinated OS compounds with bimolecular rate constants k BM more than 1000x larger than k BM for the reaction between O2 •− and ethylene carbonate. We further identified the products of reaction of a model OS compound using multiple nuclear magnetic resonance (NMR) methods and with gas chromatography/mass spectroscopy. Chemical analysis measurements show that addition of potassium superoxide KO2 to a model fluorinated OS compound produces only one product. Our results indicate that that OS compounds improve battery performance by rapidly scavenging O2 •− in a way that produces a stable product and reduces or eliminates the competing chemical pathways associated with carbonate breakdown. These results provide new insights into how chemical structure impacts critical chemical reactions and may guide the design of new additives that further improve battery safety and stability.

A study on the anti-senescent effects of flavones derived from Prinsepia utilis Royle seed residue

Ethnopharmacological relevancePrinsepia utilis Royle, also known as the Anas fruit, is a unique perennial woody oil plant from Yunnan Province, China. In the ancient texts of Dongba sutras and Yunnan Southern Materia Medica, it has been documented that the local Naxi, Tibetan, and Mosuo communities extensively utilize the root and leaf fruits of green thorns for various purposes. These include treating mild-to-moderate specific dermatitis, moisturising the skin, providing protection against UV damage, aiding childbirth in pregnant women, safeguarding stomach health, reducing the risk of arteriosclerosis, and delaying aging. Aim of the studyIn this study, leftover residues from oil extraction were efficiently reused, and flavonoids were identified during subsequent extraction and separation processes. The anti-senescent effects of flavonoids in P. utilis Royle have not been systematically studied. Therefore, the objective of this study was to explore the anti-senescent properties of the flavonoids obtained from P. utilis Royle. MethodsFirst, HPLC and other analytical techniques were used to identify the components of the P. utilis Royle flavonoid (PURF). Next, DPPH, hydroxyl radicals, superoxide anion O2−, collagenase, and elastase were initially detected using in vitro biochemical assays. To examine its antioxidant properties, a zebrafish model was used, and to confirm its anti-senescent effects, a d-galactose-induced mouse aging model was employed. The anti-senescent mechanism of PURF was examined using a natural senescence HFF model. Furthermore, the anti-senescent target was confirmed using a 3D full T-Skin™ model. ResultsIn vitro biochemical assays demonstrated that flavones exhibited potent antioxidant activity and anti-senescent potential by inhibiting DPPH, hydroxyl radicals, superoxide anion O2−, collagenase, and elastase. It significantly enhanced the antioxidant effect on zebrafish while suppressing ROS and inflammatory injury, up-regulating COL1A1, COL3A1, AMPK, and mTOR gene expression and down-regulating MMP-9, TGF-β, p21, and p16 gene expression suggesting its potential anti-senescent ability. Findings from the D-galactose-induced aging mouse model showed that PURF greatly increased SOD levels, while simultaneously decreasing HYP and MDA levels. In addition, when PURF was given to the HFF cell and 3D full T-Skin™ model, consistent trends were observed in gene and protein expression, with up-regulation of COL1A1, COL3A1, AMPK, and mTOR genes and down-regulation of TGF-β, MMP-1, MMP-9, p21, and p16 genes. Therefore, these preliminary findings indicate that flavones can modulate AMPK/mTOR/TGF-β signalling pathways to exert its influence. ConclusionThe kernel residue of natural P. utilis Royle oil extracted from Yunnan province was previously considered agricultural waste, but we successfully extracted and isolated its flavonoid components. Our preliminary studies demonstrated its potential as an environmentally friendly anti-senescent raw material.

Nb-doping of cation-disordered rocksalt oxides with B2O3 surface modification for superior performance cathode

As the growing price and inadequate reserves of cobalt, the demand for cobalt-free materials with superior energy density to apply in Li-ion batteries has increased distinctly. Li-rich cation disordered rocksalt (DRX) material has aroused research hotspot because of high specific capacity and wide compositional space. However, irreversible oxygen loss as well as sluggish kinetic raise the problem in large polarization and inevitable capacity decay in cycling process, which have impeded the commercialization of these electrode materials. In this work, we have synthesized cobalt-free boron trioxide (B2O3)-modified Li1.2Ni0.3Ti0.3Nb0.2O2 compounds with cation disordered rocksalt structure through mechanochemical method. It is a fact that B2O3-modified cathodes possess outstanding cyclic stability as well as rate properties. Particularly, the Li1.2Ni0.3Ti0.3Nb0.2O2 electrode with 2.0 wt% B2O3 displayed a competitive capacity of 192.4 mAh/g at 10 mA g−1 and retained 134.7 mAh/g after 100 charge/discharge times. The redox mechanism is explored through ex-situ XPS measurement, verifying the reversible cationic redox of Ni2+/Ni4+ accompanying small Ti4+/Ti3+ reduction and anionic O2−/O− evolution, which results in unusual high capacity. Such an optimized surface modification combines with the Nb doping, can promote Li ion transport, reduce polarization, protect cathode from reacting with electrolyte. These findings provide important implications to improve performance of DRX cathodes.

Synergetic impact of dual substitution on anionic–Cationic activity of P2-type sodium manganese oxide

P2-type sodium-deficient cathodes with the local Na–O–A configuration (A=Li, Mg, Zn, and vacancy) have attracted great interest due to their high capacity, stemming from the additional contribution of the oxygen-redox chemistry. However, such materials suffer from irreversible oxygen redox, oxygen release, structural distortion, and capacity fading. Herein, we introduce a dual-doping Li/Cu strategy to improve the properties of P2-NaxMnO2 cathode material. The unique sodium-storage mechanism in P2-Na0.75[Li0.15Cu0.15Mn0.7]O2 is verified using operando X-ray diffraction (o-XRD), X-ray absorption, X-ray photoelectron spectroscopy, and magnetic susceptibility methods. O-XRD and 7Li solid-state nuclear magnetic resonance analysis reveal that the P2 phase is maintained within charge and discharge; however, at high voltage, a small portion of O-type stacking faults are emerged due to the migration of Li to octahedral Na sites. Furthermore, various spectroscopy and magnetometry techniques combined with density functional theory calculation demonstrate the stable activity of cationic Cu2+/Cu3+ and Mn3+/Mn4+ and anionic O2−/(O2)n− redox processes. This work highlights the efficacy of Li and Cu doping in P2-type layered materials and the contribution of oxygen redox to additional capacity at high voltages, suggesting the potential for future development of cathode materials for Na-ion batteries with oxygen redox.

Efficient and green oxidation of 2-aminophenol catalyzed by tetra-(p-methoxyphenyl) porphyrin complexes anchored on chitosan in bicarbonate solution

The study explored the catalytic activities of chitosan-supported tetra (p-methoxyphenyl) porphyrin complexes 1–3 in the heterogeneous activation of the aerobic oxidation dimerization of 2-aminophenol (OAP) to 2-aminophenoxazine-3-one (APX) in the presence of bicarbonate, simulating the function of phenoxazinone enzyme synthase. The oxidation reaction was followed by recording the UV–vis spectra of the reaction mixture with time at λmax 433 nm. All chitosan-supported metalloporphyrin complexes 1–3 exhibited effective catalytic activities for OAP oxidation. Under optimal conditions, the chitosan-supported Cu(II) (Tp-OCH3PP) complex displayed the highest catalytic efficiency. Various parameters influencing the catalytic activity of Cu(II) (Tp-OCH3PP)/CTS 1 were studied. The observed rate constant of OAP oxidation exhibited a direct correlation with the concentration of supported catalyst 1 and followed Michaelis–Menten kinetics, indicating saturation of catalyst sites with increasing OAP concentration. The study investigated the impact of temperature, bicarbonate concentration, dissolved oxygen, and the reaction mechanism. Oxidation reaction of OAP catalyzed by 1 in the presence of nitro blue tetrazolium (NTB) revealed no superoxide anion O2−• was formed as a reactive species during the reaction. The chitosan-supported Cu(II) (Tp-OCH3PP) complex shows high catalytic stability and no significant changes up to the fifth run.

Mitochondria-specific near-infrared photoactivation of peroxynitrite upconversion luminescent nanogenerator for precision cancer gas therapy

Gas therapy is emerging as a highly promising therapeutic strategy for cancer treatment. However, there are limitations, including the lack of targeted subcellular organelle accuracy and spatiotemporal release precision, associated with gas therapy. In this study, we developed a series of photoactivatable nitric oxide (NO) donors NRh-R-NO (R = Me, Et, Bn, iPr, and Ph) based on an N-nitrosated upconversion luminescent rhodamine scaffold. Under the irradiation of 808 nm light, only NRh-Ph-NO could effectively release NO and NRh-Ph with a significant turn-on frequency upconversion luminescence (FUCL) signal at 740 nm, ascribed to lower N–N bond dissociation energy. We also investigated the involved multistage near-infrared-controlled cascade release of gas therapy, including the NO released from NRh-Ph-NO along with one NRh-Ph molecule generation, the superoxide anion O2⋅− produced by the photodynamic therapy (PDT) effect of NRh-Ph, and highly toxic peroxynitrite anion (ONOO‒) generated from the co-existence of NO and O2⋅−. After mild nano-modification, the nanogenerator (NRh-Ph-NO NPs) empowered with superior biocompatibility could target mitochondria. Under an 808 nm laser irradiation, NRh-Ph-NO NPs could induce NO/ROS to generate RNS, causing a decrease in the mitochondrial membrane potential and initiating apoptosis by caspase-3 activation, which further induced tumor immunogenic cell death (ICD). In vivo therapeutic results of NRh-Ph-NO NPs showed augmented RNS-potentiated gas therapy, demonstrating excellent biocompatibility and effective tumor inhibition guided by real-time FUCL imaging. Collectively, this versatile strategy defines the targeted RNS-mediated cancer therapy.

Unveiling the Role of Ruthenium in Layered Sodium Cobaltite Toward High‐Performance Electrode Enabled by Anionic and Cationic Redox

AbstractThe effect of Ru substitution on the structure and electrochemical properties of P2‐type Na0.67CoO2 is investigated. The first‐discharge capacities of Na0.67CoO2 and Na0.6 [Co0.78Ru0.22]O2 materials are 128 and 163 mAh g−1 (23.5 mA g−1), respectively. Furthermore, the rate capability is improved due to the electro‐conducting nature of Ru doping. Operando X‐ray diffraction analysis reveals that the Na0.67CoO2 does not undergo a phase transition; however, multiple Na+/vacancy ordered superstructures within the P2 phase appear during Na+ extraction/insertion. In contrast, the Na0.6[Co0.78Ru0.22]O2 material undergoes a P2–OP4 phase transition during desodiation, with no formation of Na+/vacancy ordering within the P2 phase. The increased discharge capacity of Na0.6[Co0.78Ru0.22]O2 is most likely associated with additional cationic Ru4+/Ru5+ redox and increased anionic O2−/(O2n−) redox participation. Combined experimental (galvanostatic cycling, X‐ray absorption spectroscopy, differential electrochemical mass spectrometry) and theoretical (density functional theory calculations) studies confirm that Ru substitution provokes the oxygen‐redox reaction and that partial O2 release from the oxide lattice is the origin of the reaction. The findings provide new insight for improving the electrode performance of cathode materials via 4d Ru substitution and motivate the development of a new strategy for the design of high‐capacity cathode materials for sodium‐ion batteries.

Intimate coupling of gC3N4/CdS semiconductor on eco-friendly biocarrier loofah sponge for enhanced detoxification of ciprofloxacin

Ciprofloxacin is one of the antibiotics predominantly used to treat bacterial infections, however excess usage, and release of antibiotic from various sources to the environment can cause severe risks to human health since it was considered as emerging pollutant. This study deals with the intimately coupled photocatalysis and biodegradation (ICPB) of ciprofloxacin using gC3N4/CdS photocatalytic semiconductor and eco-friendly renewable loofah sponge as biocarrier in the ICPB. The photocatalyst gC3N4/CdS was prepared and their synergistic photocatalytic degradation of ciprofloxacin were assessed and the results shows that gC3N4/CdS (20%) exhibit 79% degradation efficiency in 36 h. Further ICPB exhibited enhanced ciprofloxacin degradation 95% at 36 h. The 62.4% and 81.1% of chemical oxygen demand (COD) removal was obtained in the photocatalysis and ICPB respectively. Enhanced degradation of ciprofloxacin and COD removal was due to the synergetic photoelectrons generated from the gC3N4/CdS (20%) transferred to the bacterial communities which intensely mineralize the degradation products produced from the photocatalysis process. Furthermore, production of hydroxyl •OH and superoxide radical anion O2• were identified actively involved in the degradation of ciprofloxacin. The biocarrier loofah sponge provided favourable environment to the bacterial communities for the formation of biofilm and production of extracellular polymeric substances (EPS). Excess quantity of EPS production in the ICPB helps in the prevention of toxicity of photocatalyst to bacterial communities as well as facilitate the extracellular electron transfer process. This work provides a novel path for enhanced degradation of ciprofloxacin using eco-friendly, low cost and renewable biocarrier loofah sponge in the ICPB system.

Nonhost Resistance of Thinopyrum ponticum to Puccinia graminis f. sp. tritici and the Effects of the Sr24, Sr25, and Sr26 Genes Introgressed to Wheat

The damage to wheat crops by stem rust poses a threat to the food security of the world’s population. The species Thinopyrum ponticum (Podpěra, 1902) (Z.-W. Liu and R.-C. Wang, 1993) is a non-host for the stem rust fungus Puccinia graminis f. sp. tritici Eriks. and Henn. (Pgt). The Sr24, Sr25, and Sr26 genes, transferred from the Th. ponticum to the wheat gene pool, protect cultivars from the disease in different regions of the world. The study of the non-host resistance (NHR) of Th. ponticum and the effects of the introgressed Sr24, Sr25, and Sr26 genes in wheat is important for breeding cultivars with durable resistance to stem rust. The aim of the research is to study the interaction of Pgt with Th. ponticum and common wheat lines with the Sr24, Sr25, and Sr26 genes, in addition to determining the role of ROS in resistance. Wheat lines with Sr24, Sr25, and Sr26 were resistant to the West Siberian Pgt population. Using cytological methods, it was found that the NHR of Th. ponticum and Sr24, Sr25, and Sr26 led to inhibition of the most inoculumdevelopment on the plant surface. This was mainly due to the suppression of the appressoria development and their death at the stage of penetration into the stomata. Upon contact of Pgt appressoria with stomatal guard cells, the generation of the superoxide anion O2•− was revealed. This interaction is similar to the stomatal immunity of Arabidopsis thaliana to non-pathogenic bacteria. The results of our studies show that the Sr24, Sr25, and Sr26 genes reproduce the action of some NHR mechanisms in wheat.

Methylcyclopropene treatment retards the yellowing in pak choi (Brassica rapa subsp. Chinensis) through modulating the programmed cell death during storage at 20°C

The deterioration of post-harvest quality in plants has been shown to be connected with the occurrence of programmed cell death (PCD). Our previous research indicated that 5 μL L−1 1-Methylcyclopropene (1-MCP) delays the yellowing of post-harvest pak choi leaves. However, whether 1-MCP alleviates pak choi yellowing through regulating PCD process, and the regulatory mechanism of 1-MCP on PCD are still unclear. Results showed that 5 μL L−1 1-MCP could retard the PCD process of pak choi as proved by the maintenance of lower cytochrome C content and caspase-3 activity. The results of cell mortality and trypan blue staining further confirmed this view. Forty-five differentially expressed genes (DEGs) involving PCD of pak choi were identified in the transcriptome data. The treatment suppressed the over-accumulation of reactive oxygen species (ROS) (superoxide anion O2·− and hydrogen peroxide H2O2), lipid membrane oxidation, ethylene production, and expression of their related genes (BcRBOHC, BcRBOHD, BcLOX1/3/5, BcACO, BcACO4 and BcEIN3)) during senescence. This relationship was also connected to the preservation of higher level in antioxidant capacity of antioxidase and antioxidants (ascorbate-glutathione (AsA-GSH)), as well as high expression of their related genes (BcSOD, BcAPX, and BcGR) in 1-MCP-treated pak choi. Moreover, 1-MCP down-regulated the transcript of genes involved in PCD, regulated the expression of genes associated with mitochondrial membrane transport, respiration and signaling, and chloroplast membrane transport and REDOX, thereby contributing to the inhibition of PCD. The correlation analysis revealed that pak choi yellowing was positively related with the process of PCD. Taken together, the present study indicated that 1-MCP could delay the yellowing of pak choi through mitigating PCD process, involving the regulation of ROS metabolism, membrane lipid degradation, antioxidant status and ethylene production.

Superoxide Anion Chemistry-Its Role at the Core of the Innate Immunity.

Classically, superoxide anion O2•- and reactive oxygen species ROS play a dual role. At the physiological balance level, they are a by-product of O2 reduction, necessary for cell signalling, and at the pathological level they are considered harmful, as they can induce disease and apoptosis, necrosis, ferroptosis, pyroptosis and autophagic cell death. This revision focuses on understanding the main characteristics of the superoxide O2•-, its generation pathways, the biomolecules it oxidizes and how it may contribute to their modification and toxicity. The role of superoxide dismutase, the enzyme responsible for the removal of most of the superoxide produced in living organisms, is studied. At the same time, the toxicity induced by superoxide and derived radicals is beneficial in the oxidative death of microbial pathogens, which are subsequently engulfed by specialized immune cells, such as neutrophils or macrophages, during the activation of innate immunity. Ultimately, this review describes in some depth the chemistry related to O2•- and how it is harnessed by the innate immune system to produce lysis of microbial agents.

Exogenous melatonin ameliorates yellowing of postharvest pak choi (Brassica rapa subsp. chinensis) by modulating chlorophyll catabolism and antioxidant system during storage at 20 °C

The objective of this study was to investigate the regulatory mechanism of melatonin (MT) treatment on leaf yellowing of pak choi during storage at 20 °C. Results showed that 500 μmoL L−1 MT alleviated the yellowing process of pak choi as proved by the maintenance of high level of leaf colour, chlorophyll content and chlorophyll fluorescence parameters (Fo, Fm and Fv/Fm), and the market life of pak choi was extended by 2 d compared to the control. The weight loss and respiration rate were effectively alleviated by MT treatment. MT treatment restrained chlorophyll breakdown by down-regulating the activity of chlorophyll-degrading enzymes (chlorophyllase CLH, pheophytinase PPH and Mg-dechelatase MDS) and expression of their related genes (BcCLH, BcPPH1/2, BcSGR, BcHCAR, BcNYC1 and BcCAO). Meanwhile, MT suppressed the over-accumulation of reactive oxygen species (ROS) (superoxide anion O2·− and hydrogen peroxide H2O2), and lipid membrane oxidation and associated gene (BcLOX) expression during senescence, thus helping to keep green colour of pak choi. This relationship was also connected to the maintenance of higher level in antioxidant ability of antioxidase (superoxide dismutase SOD, ascorbate peroxidase APX, peroxidase POD and catalase CAT) and antioxidants (ascorbate-glutathione (AsA-GSH)), as well as high expression of their related genes (BcSOD, BcPOD, BcCAT, BcGPX and BcAPX) in pak choi treated with MT. In conclusion, these findings suggested that MT could delay the yellowing of pak choi, involving the regulation of chlorophyll metabolism, ROS metabolism, membrane lipid degradation, and antioxidant capacity. The results provide a possible target for delaying the yellowing of green vegetables.

Coexpression modules constructed identifies regulation pathways of winter jujube (Ziziphus jujuba Mill. 'Dongzao') following postharvest treatment with ozone

Winter jujube (Ziziphus jujuba Mill. 'Dongzao') is a member of the Rhamnaceae family known for its favorable nutritional and flavor profile. It has been considered a unique and excellent cultivar in China. Nevertheless, fresh winter jujube fruit is sensitive to diseases because of microbial decay and mechanical damage. Ozone treatment (OT) is reported to prevent fruit decay in many fruit during postharvest storage. In the present study, we first found that postharvest winter jujube fruit treated with 2.14 mg m −3 ozone concentration exhibited decreased accumulation of superoxide anion O2− generation rate, H2O2 content and MDA content and increased activities of aseorbate peroxidase (APX), catalase(CAT), peroxidase (POD), superoxide dismutase (SOD) and GSH content in the antioxidant bioactive compounds or enzymes, which was beneficial to the enhancement of antioxidant capacity over the entire storage period compared with the other three groups. Then, label-free quantification proteomics and weighted gene coexpression network analysis (WGCNA) of winter jujube fruit revealed black module (containing 94 differentially expressed proteins with increased and decreased levels of abundance respectively) was of greatest importance to study mechanisms of ozone preservation on winter jujube. Gene Ontology (GO) and KEGG annotation and enrichment analysis showed that the black module included ribosomal and glutathione metabolism pathways, suggesting the involvement of these pathways in ozone-mediated antisenescence. There are 26 hub proteins in the black module, and 6 intersecting proteins through protein–protein interaction (PPI) network analysis and KEGG annotation and enrichment analysis, a 60 S acidic ribosomal protein P2B, a 60 S ribosomal protein L12, a 40 S ribosomal protein S19–3, and a phospholipid hydroperoxide glutathione peroxidase, and others. Our qRT-PCR results were consistent with the RNA sequencing results, confirming our findings. We propose a link between protein profiles and physiological traits important for preservation, which identified the WGCNA modules, the hub proteins, and the important pathways, and provided new insights into the molecular mechanisms of OT as the method of storage and preservation of fresh fruit at the proteomic level.

Front Cover: The Cesium Oxide Mercuride Cs18Hg8O6 (Z. Anorg. Allg. Chem. 10/2022)

The cover picture shows crystal structure and electronic structure of the compound Cs18Hg8O6. It contains the first isolated mercuride anions, cubic [Hg8]6− entities which are coordinated by Cesium cations. As further anions oxide anions O2− are present in the structure and form a 3D scaffolding network of [Cs6O] octahedra. The ′mercubanide′ anions are arranged in a cubic body-centered topology. The calculated electronic structure is shown as a spaghetti representation. The energy bands below the Fermi level can be attributed to either mercuride or oxide anions, emphasizing the picture of an ionic double salt. The mercuride Cs18Hg8O6 complements a series of compounds with anions from relativistic atoms, showing peculiar features of the chemical bonding. Below, a photograph shows a typical rod-shaped crystal with dark metallic luster.(DOI: 10.1002/zaac.202100389).

S-scheme ZIF-8/Ag2S heterojunction photocatalyst for degradation of organic pollutant using batch and external loop airlift reactors

The photocatalytic degradation of Rh.B was investigated using ZIF-8/Ag2S nanocomposite photocatalyst. In the present study, Ag2S NPs were dispersed on the surface of ZIF-8 forming a kind of a new high-efficiency heterogeneous photocatalyst ZIF-8/Ag2S nanocomposite via co-precipitation method. The crystal structure, optical properties and the morphology of ZIF-8, Ag2S and ZIF-8/Ag2S synthesized photocatalysts were examined using N2 adsorption–desorption, XRD, DRS, FE-SEM and TEM techniques.The degradation of Rh.B was performed under irradiation of visible light to examine the performance of ZIF-8/Ag2S nanocomposite in batch and external loop airlift reactors. The results demonstrated that the ZIF-8/Ag2S has excellent photodegradation efficiency (100%) compared with pure ZIF-8 (51.6%) and Ag2S (39.7%) due to the good dispersion of agglomerate Ag2S on the surface area of ZIF-8.Moreover, the photodegradation efficiency of Rh.B using ZIF-8/Ag2S nanocomposite photocatalyst in the external loop airlift reactor was more efficient and rapid (100% degradation efficiency within 75 min) than batch reactor (100% degradation efficiency within 120 min). This is due to the well mixing and the effect of the air flow rate containing O2 which greatly improved the photocatalytic activity by reacting with the electrons to produce the superoxide anions O2− in the airlift reactor. Also, the obtained findings from the airlift reactor showed a significant increase in the degradation efficiency with air flow rate up to 40 LPM, after which practically, the degradation efficiency decreases.Several factors influencing the photoactivity of the composite include the pH of the Rh.B solution, initial concentration of Rh.B, ZIF-8/Ag2S photocatalyst dose, initial Rh.B concentration, and dye type. The ZIF-8/Ag2S nanocomposite showed good stability and reusability after five reuse cycles.

Molecular Basis for the Interaction of Catalase with d-Penicillamine: Rationalization of Some of Its Deleterious Effects.

d-Penicillamine (d-Pen) is a sulfur compound used in the management of rheumatoid arthritis, Wilson's disease (WD), and alcohol dependence. Many side effects are associated with its use, particularly after long-term treatment. However, the molecular basis for such side effects is poorly understood. Based on the well-known oxidase activity of hemoproteins and the participation of catalase in cellular H2O2 redox signaling, we posit that d-Pen could inactivate catalase, thus disturbing H2O2 levels. Herein, we report on the molecular basis that could partly explain the side effects associated with this drug compound, and we demonstrate that it induces the formation of compound II, a temporarily inactive state of the enzyme, through two distinct mechanisms. Initially, d-Pen reacts with native catalase and/or iron metal ions, used to mimic non-heme iron overload observed in long-term treated WD patients, to generate thiyl radicals. These radicals partake in a futile redox cycle, thus producing superoxide radical anions O2•- and hydrogen peroxide H2O2. Then, either H2O2 unexpectedly reacts with reduced CAT-Fe(II) to produce compound II or both aforementioned reactive oxygen species intervene in compound II generation through compound I formation and then reduction. These findings support the evidence that d-Pen could perturb H2O2 redox homeostasis through transient but recurring catalase inactivation, which may in part rationalize some deleterious effects observed with this therapeutic agent, as discussed.

Electrophysical Properties of Polycrystalline C12A7:e− Electride

This article demonstrates the possibility of creating memory devices based on polycrystalline mayenite. In the course of the study, structural characterization (XRD, TEM) of ceramic samples of mayenite was carried out, as well as a study of the spectral (THz range) and electrophysical characteristics. Materials obtained by calcination at high (1360–1450 °C) temperatures in an inert argon atmosphere differ in the degree of substitution of oxygen anions O2− for electrons, as indicated by the data on the unit cell parameters and dielectric constant coefficients in the range of 0.2–1.3 THz, as well as differences in the conducting properties of the samples under study by more than five orders of magnitude, from the state of the dielectric for C12A7:O2− to the conducting (metal-like) material in the state of the C12A7:e− electride. Measurements of the current–voltage characteristics of ceramic C12A7:e− showed the presence of memristive states previously detected by other authors only in the case of single crystals. The study of the stability of switching between states in terms of resistance showed that the values of currents for states with high and low resistance remain constant up to 180 switching cycles, which is two times higher than the known literature data on the stability of similar prototypes of devices. It is shown that such samples can operate in a switch mode with nonlinear resistance in the range of applied voltages from –1.3 to +1.3 V.