O2 Release Research Articles

Step-scheme perylenediimide supramolecular nanosheet and TiO2 nanoparticle composites for boosted water splitting performance

Adjusting the band gap of organic-inorganic composites by chemical bonding can effectively construct Step-scheme (S-scheme) heterojunctions, featuring properties of fast photogenerated charge migration and excellent photocatalytic performance. In this work, a novel perylene-3, 4, 9, 10-tetracarboxylicdiimide (PDI)-titanium dioxide (TiO2) heterojunction is elaborately synthesized through simple solvent compounding method. The monodispersed spherical TiO2 nanoparticles was prepared with the capping agents of oleylamine and oleic acid, and suffered by a ligand exchange process with nitrosonium tetrafluoroborate (NOBF4) to remove oleylamine and oleic acid. The NOBF4 ligands were further replaced by PDI super molecular nanosheets to obtain two dimensional (2D)-zero dimensional (0D) PDI-TiO2 composites. TiO2 nanoparticles are evenly anchored on the surface of PDI nanosheets with intimate contact. The PDI-TiO2 composites has emerged considerably superior activity in hydrogen evolution. The highest hydrogen evolution rate for PDI-TiO2composites with the PDI weight percentage of 2.4% was 9766 μmol h−1 g−1 under solar light irradiation, which is 2.56 times of TiO2-NOBF4 catalyst. Moreover, PDI-TiO2 composites possess stoichiometric overall water splitting performance with H2 and O2 release rates of 238.20 and 114.18 μmol h−1 g−1. The superior photocatalytic performance of PDI-TiO2 composites can be attributed to the dramatic increase in visible and NIR light absorption caused by π-π stacking structure of PDI, the prevented charge recombination by the S-scheme heterojunction, and the enhanced oxygen evolution by the stronger oxidation capability of PDI. PDI supramolecular nanosheets may work as a novel functional support for many types of semiconductor nanomaterials as graphene, which will display a wide range of application prospects in the energy and environmental fields.

The contribution of fish and seaweed mariculture to the coastal fluxes of biogenic elements in two important aquaculture areas, China

Carbon, nitrogen, phosphorus and oxygen (CNPO) are essential biogenic elements, driving life activities in marine environments. However, the integrated research of fish and seaweed culture on the fluxes of CNPO is scarce. To bridge the research gap, the contribution of mariculture of fish and seaweeds to the fluxes of CNPO in two important mariculture provinces, Fujian and Guangdong, in China, was investigated for the first time. Data from published literature and this study were integrated to calculate the CNPO fluxes using relative formulas. CNP release and O2 loss caused by fish mariculture increased with year (2003−2020) and reached 185.55 ± 3.18 Gg C, 35.92 ± 0.51 Gg N, 7.27 ± 0.24 Gg P and 644.18 ± 11.05 Gg O2 for Fujian and 215.81 ± 2.51 Gg C, 41.77 ± 0.40 Gg N, 8.47 ± 0.19 Gg P and 749.23 ± 8.71 Gg O2 for Guangdong in 2020. The averaged P fluxes due to fish mariculture in Fujian and Guangdong during 2016–2020 are 2.2 folds of the Min River and 69 % of the Pearl River, respectively. CNP removal and O2 generation by seaweed culture in Fujian also increased with year (2003–2020) and reached 555.74 ± 16.45 Gg C, 58.44 ± 4.83 Gg N, 7.80 ± 1.41 Gg P and 1481.97 ± 43.86 Gg O2 in 2020. In contrast, seaweed culture in Guangdong resulted in maximal C (39.81 ± 1.43 Gg), N (4.33 ± 0.26 Gg) removal and O2 (106.15 ± 3.82 Gg) release in 2013 and maximal P (0.41 ± 0.03 Gg) removal in 2019. The averaged N and P fluxes due to seaweed culture in Fujian during 2016–2020 are 69 % and 2.4 folds of the Min River, respectively. The different mariculture structure leads to a net CNP sink in Fujian but a net CNP source in Guangdong. The net CNP source may lead to seawater acidification, eutrophication and deoxygenation in coastal areas. These findings supply solid data for adjusting mariculture structure to achieve CNPO neutrality within mariculture.

One-step construction of oxygen vacancies and coating to improve lithium storage performance of Li-rich layered oxides

With the advantages of higher capacity and lower price, Li-rich layered oxides have tremendous potential to become an advanced cathode material in the next generation Li-ion batteries (LIBs). Nevertheless, the commercialization of Li-rich layered oxides is seriously hindered by the large initial non-reversible capacity loss, inferior rate performance, capacity and voltage decay. Herein, a multi-strategy synergistic Li1.2Ni0.13Co0.13Mn0.54O2 (LRNCM) sample was prepared by the simultaneous establishment of oxygen vacancies and Nb2O5/C coating by C10H5NbO20·xH2O pyrolysis. The oxygen vacancies on the surface inhibit irreversible O2 release and promote the diffusion of Li+ ions, while the well-stabilized Nb2O5/C coating alleviates the corrosion of electrolytes. As a result, the initial coulombic efficiency (ICE) is increased from 60.41% to 76.95%. The capacity retention is improved from 80.6% to 86.8% after 100 cycles at 0.5 C, and the high-rate performance increases from 87 mAh g−1 to 144.6 mAh g−1 at 10 C. This work shows that the synergistic effect of oxygen vacancies and Nb2O5/C coating on LRNCM can effectively improve the charge/discharge reversibility, cycle stability and rate performance.

Ru-Doping of P2-NaxMn0.75Ni0.25O2-Layered Oxides for High-Energy Na-Ion Battery Cathodes: First-Principles Insights on Activation and Control of Reversible Oxide Redox Chemistry

Design and development of high-energy, efficient, and structurally stable positive electrodes for Na-ion batteries (NIBs) have recently been focusing on layered transition metal oxides (NaxTMO2, 0 < x < 1). When doped with late transition metals, the redox reactions ensuring the charge compensation upon Na+ removal can rely on the direct participation of anionic chemistry, with encouraging outcomes in terms of both energy density and power. However, the control of reversible O2–/O– reactions is still a major issue, as the undesired release of O2 can lead to detrimental effects on cathode capacity and overall cell stability. The fine-tuning of metal–oxygen bond covalency has recently emerged as a promising strategy toward the reversible access of oxygen redox. Following the route paved by Ru-based Li-rich cathode materials, we hereby present a first-principles investigation of a Ru-doped NaxTMO2 (TM = Ru, Ni, and Mn) system and the related structural and electronic properties of interest for NIB applications. We aim to dissect the specific role of each element sublattice in compensating the electronic charge along desodiation, with a major focus on the anionic contribution. The oxygen activity is addressed in the high-voltage range (i.e.,xNa = 0.25), and the underlying mechanism is derived from PBE + U(-D3BJ) calculations. We also discuss the effects of Mn deficiency as a suitable site for the formation of low-energy superoxide species via preferential breaking of the Ni–O bond. Conversely, breaking a Ru–O bond is unlikely to occur, which assesses the key role of the Ru dopant in stabilizing the oxide lattice and enabling the desired reversible conditions. Our results also highlight the oxygen vacancy formation energy as an effective descriptor for different activities toward the O2–/O–/O2 evolution. All these theoretical insights can be useful to drive further experimental efforts toward the optimal design of efficient and high-energy NIB cathodes with enhanced practical reversible capacity.

Myoglobin-Pyruvate Interactions: Binding Thermodynamics, Structure-Function Relationships, and Impact on Oxygen Release Kinetics.

Myoglobin (Mb), besides its roles as an oxygen (O2) carrier/storage protein and nitric oxide NO scavenger/producer, may participate in lipid trafficking and metabolite binding. Our recent findings have shown that O2 is released from oxy-Mb upon interaction with lactate (LAC, anerobic glycolysis end-product). Since pyruvate (PYR) is structurally similar and metabolically related to LAC, we investigated the effects of PYR (aerobic glycolysis end-product) on Mb using isothermal titration calorimetry, circular dichroism, and O2-kinetic studies to evaluate PYR affinity toward Mb and to compare the effects of PYR and LAC on O2 release kinetics of oxy-Mb. Similar to LAC, PYR interacts with both oxy- and deoxy-Mb with a 1:1 stoichiometry. Time-resolved circular dichroism spectra revealed that there are no major conformational changes in the secondary structures of oxy- or deoxy-Mb during interactions with PYR or LAC. However, we found contrasting results with respect to binding affinities and substrate preference, where PYR has higher affinity toward deoxy-Mb when compared with LAC (which prefers oxy-Mb). Furthermore, PYR interaction with oxy-Mb releases a significantly lower amount of O2 than LAC. Taken together, our findings support the hypothesis that glycolytic end-products play a distinctive role in the Mb-rich tissues by serving as novel regulators of O2 availability, and/or by impacting other activities related to oxy-/deoxy-Mb toggling in resting vs. exercised or metabolically activated conditions.

Phase evolution of a novel silicon-alumina-fused mullite-containing Ti2O3 refractory at 1300 °C in N2

A novel silicon-alumina-fused mullite-containing Ti2O3 composite refractory is prepared and sintered in the presence of solid carbon at 1300 °C in N2. The sintered samples exhibit a functional gradient characteristic. The phase evolution can be described as follows: Passive and active oxidation of Si to form SiO2 and SiO to reduce the partial pressure of oxygen. SiO(g) and Si react with N2 to form Si3N4 respectively. As the temperature increases and the partial pressure of oxygen decreases, Ti2O3 reacts with CO and N2 to form Ti(C,N)ss, which is accompanied by the release of O2. Si3N4 fixes the O2 and reacts to form Si2N2O, and Si2N2O reacts with Al2O3 to form O′-Sialon, thereby realizing the transformation from Si3N4 to Sialon. CO and residual carbon from the pyrolysis of phenolic resin react with SiO(s) and Si to form SiC. The dense layer formed by SiC and SiO2 blocks the diffusion of external gas to the central parts of the samples, there is still free Si which can continue to react and transform into a non-oxide reinforcing phase. In this paper, the reaction models are presented.

Li‐Rich Mn–Mg Layered Oxide as a Novel Ni‐/Co‐Free Cathode

AbstractAlthough Li2MnO3 exhibits high capacity via anionic oxygen redox, it suffers from rapid capacity decay owing to structural disordering accompanying irreversible Mn migration and O2 release. To promote the reversibility of the anionic redox reaction, Li1.8Mg0.3Mn0.9O3 as a novel cathode material, prepared by partially substituting Li+ and Mn4+ of Li2MnO3 with the redox‐inactive Mg2+ as a structural stabilizer is proposed. Li1.8Mg0.3Mn0.9O3 delivers a high specific capacity and energy density of ≈310 mAh g−1 and ≈915 Wh kg−1, respectively. In particular, the power‐capability and cycle performance of Li1.8Mg0.3Mn0.9O3 greatly surpass those of Li2MnO3. Through first‐principles calculations and various experiments, it is revealed that Mg substitution effectively suppresses the Mn migration by stabilizing Mn cations in the original sites at the charged state. The energetically stabilized layered structure disfavors the distortion of the MnO6 octahedra, which induces the oxygen dimer (OO) formation through the metal–oxygen decoordination, thus mitigating oxygen release.

Water Oxidation Catalyzed by a Bioinspired Tetranuclear Manganese Complex: Mechanistic Study and Prediction.

Density functional theory calculations were utilized to elucidate the water oxidation mechanism catalyzed by polyanionic tetramanganese complex a [MnIII 3 MnIV O3 (CH3 COO)3 (A-α-SiW9 O34 )]6- . Theoretical results indicated that catalytic active species 1 (Mn4 III,III,IV,IV ) was formed after O2 formation in the first turnover. From 1, three sequential proton-coupled electron transfer (PCET) oxidations led to the MnIV -oxyl radical 4 (Mn4 IV,IV,IV,IV -O⋅). Importantly, 4 had an unusual butterfly-shaped Mn2 O2 core for the two substrate-coordinated Mn sites, which facilitated O-O bond formation via direct coupling of the oxyl radical and the adjacent MnIV -coordinated hydroxide to produce the hydroperoxide intermediate Int1 (Mn4 III,IV,IV,IV -OOH). This step had an overall energy barrier of 24.9 kcal mol-1 . Subsequent PCET oxidation of Int1 to Int2 (Mn4 III,IV,IV,IV -O2 ⋅) enabled the O2 release in a facile process. Furthermore, apart from the Si-centered complex, computational study suggested that tetramanganese polyoxometalates with Ge, P, and S could also catalyze the water oxidation process, where those bearing P and S likely present higher activities.

3D Printed Integrated Bionic Oxygenated Scaffold for Bone Regeneration.

The repair of large bone defects remains a challenging problem in bone tissue engineering. Ischemia and hypoxia in the bone defect area make it difficult for seed cells to survive and differentiate, which fail to perform effective tissue regeneration. Current oxygen-producing materials frequently encounter problems such as a rapid degradation rate, insufficient mechanical properties, difficult molding, and cumbersome fabrication. Here, a novel three-dimensional (3D) printed integrated bionic oxygenated scaffold was fabricated with gelatin-CaO2 microspheres, polycaprolactone (PCL), and nanohydroxyapatite (nHA) using low-temperature molding 3D printing technology. The scaffold had outstanding mechanical properties with bionic hierarchical porous structures. In vitro reports showed that the scaffold exhibited excellent cytocompatibility and could release O2 sustainably for more than 2 weeks, which significantly enhanced the survival, growth, and osteogenic differentiation of bone marrow mesenchymal stem cells under hypoxia. In vivo experiments revealed that the scaffold facilitated efficient bone repair after it was transplanted into a rabbit calvarial defect model. This result may be due to the scaffolds reducing hypoxia-inducible factor-1α accumulation, improving the expression of osteogenic regulatory transcription factors, and accelerating osteogenesis. In summary, the integrated bionic PCL/nHA/CaO2 scaffold had excellent capabilities in sustainable O2 release and bone regeneration, which provided a promising clinical strategy for bone defect repair.

An NIR-II Photothermally Triggered "Oxygen Bomb" for Hypoxic Tumor Programmed Cascade Therapy.

Hypoxia, as a characteristic feature of solid tumors, has a close relationship with tumor resistance to photodynamic therapy (PDT) and chemotherapy. Perfluorocarbon (PFC) is reported to relieve hypoxic in solid tumors by acting as an oxygen carrier via several nanostructures. However, the oxygen delivery process is mostly driven by a concentration gradient, which is uncontrollable. Herein, a photothermally controlled "oxygen bomb" PSPP-Au980 -D is designed by encapsulating a PFC core within a functionalized bilayer polymer shell. Near-infrared second window photothermal agent gold nanorods with excellent photo-to-heat energy-conversion ability are fabricated on the surface of the polymer shell via an innovative modified two-step seedless ex situ growth process to thermally trigger O2 release. Then, a programmed cascade therapy strategy is customized for hypoxic orthotopic pancreatic cancer. First, PSPP-Au980 -D is irradiated by a 980nm laser to photothermally trigger O2 infusing into the hypoxic tumor microenvironment, which is accompanied by local hyperemia and doxorubicin release. Subsequently, a 680nm laser is used to generate singlet oxygen in the oxygenated tumor microenvironment for PDT. This choreographed programmed cascade therapy strategy will provide a new route for suppressing hypoxic tumor growth under mild conditions based on controllable and effective oxygen release.

Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study.

The design of molecular water oxidation catalysts (WOCs) requires a rational approach that considers the intermediate steps of the catalytic cycle, including water binding, deprotonation, storage of oxidizing equivalents, O–O bond formation, and O2 release. We investigated several of these properties for a series of base metal complexes (M = Mn, Fe, Co, Ni) bearing two variants of a pentapyridyl ligand framework, of which some were reported previously to be active WOCs. We found that only [Fe(Py5OMe)Cl]+ (Py5OMe = pyridine-2,6-diylbis[di-(pyridin-2-yl)methoxymethane]) showed an appreciable catalytic activity with a turnover number (TON) = 130 in light-driven experiments using the [Ru(bpy)3]2+/S2O82– system at pH 8.0, but that activity is demonstrated to arise from the rapid degradation in the buffered solution leading to the formation of catalytically active amorphous iron oxide/hydroxide (FeOOH), which subsequently lost the catalytic activity by forming more extensive and structured FeOOH species. The detailed analysis of the redox and water-binding properties employing electrochemistry, X-ray absorption spectroscopy (XAS), UV–vis spectroscopy, and density-functional theory (DFT) showed that all complexes were able to undergo the MIII/MII oxidation, but none was able to yield a detectable amount of a MIV state in our potential window (up to +2 V vs SHE). This inability was traced to (i) the preference for binding Cl– or acetonitrile instead of water-derived species in the apical position, which excludes redox leveling via proton coupled electron transfer, and (ii) the lack of sigma donor ligands that would stabilize oxidation states beyond MIII. On that basis, design features for next-generation molecular WOCs are suggested.

Exploring the connection of physical habitat health of the wetland with its gas regulating services

Many scholars assessed habitat health and measured gas regulation service of wetlands separately. However, no such targeted work was done to answer how habitat health can control gas regulation? Therefore, the present study investigated the role of habitat health on the gas regulation service of wetlands. Multi-parametric Machine Learning (ML) based modelling approach was applied to assess habitat health considering physical wetland hydrological factors and habitat degrading factors. Three primary atmospheric gas regulation functions of wetland, namely Methane (CH4) emission, Carbon (C) sequestration, and Oxygen (O2) release, were observed associating with habitat health. Very poor habitat health prevailed over 227 km2 of wetland, whereas very good habitat health covered 299 km2 of wetland. But out of the very good habitat health zone, 69% belonged to the perennial river of this region. On the other hand, it was estimated that the amount of annual CH4 emission, C sequestration, and O2 release from the wetlands of this region were respectively 8.01 × 1000 tons, 908.98 × 1000 tons and 664.51 × 1000 tons. The association of habitat health was positive with CH4 emission and negative with C sequestration and O2 release. Following the association, habitat health zone-wise variation of emission, sequestration, and release was also very prominent. The very good zone of habitat health was observed to have 60% higher CH4 average emission and 56% lesser C sequestration than very poor habitat health.

Antioxidant properties of bee propolis and an important component, galangin, described by X-ray crystal structure, DFT-D and hydrodynamic voltammetry.

Propolis is produced by honeybees and used to seal their hives for defensive purposes and has been used in ethnopharmacology since ancient times. It is a lipophilic material containing a large collection of naturally produced plant organic molecules, including flavonoids. The flavonoid galangin is consistently found in propolis, independent of the hive geographical location and its X-ray crystal and molecular structure is reported. The antioxidant scavenging of superoxide by galangin and propolis is here presented. Using a cyclic voltammetry technique developed in our lab, we show that galangin is an excellent scavenger of the superoxide radical, perhaps even better than quercetin. Our results show that galangin displays a Superoxide Dismutase (SOD) function. This is described experimentally and theoretically (DFT). Two modes of scavenging superoxide are seen for galangin: (1) superoxide radical extraction of H atom from the hydroxyl moieties located in position 3 and 5 of galangin, which are also associated with proton incorporation defining the SOD action; (2) π-π interaction among several superoxide radicals and the galangin polyphenol ring that evolve towards release of O2 and H2O2. We describe these two actions separately as their relative sequence, and/or combination, cannot be defined; all these processes are thermodynamically spontaneous, or subjected to mild barriers.

Fe-doped Co9S8@CoO aerogel with core-shell nanostructures for boosted oxygen evolution reaction

The efficiency and stability of electrocatalysts for oxygen evolution reaction (OER) generally depends on the intrinsic catalytic activity and extrinsic active sites. To intrinsically and extrinsically improve OER performance, herein, we present a novel OER catalyst of Fe-doped Co9S8@CoO aerogel with core-shell nanostructures via structural/electronic modulation strategy. The structural modulation is realized by 3D porous aerogel and core-shell nanoarchitecture which provides rich exposed active sites and guarantees effective ion diffusion and O2 release, and the amorphous shell layer of CoO can effectively prevent the corrosion of Co9S8 by the electrolyte during OER process. The electronic modulation is realized by Fe heteroatom doping for Co9S8 and oxygen vacancies in CoO layer was caused by partial oxidation process, which facilities the transfer of electrons during OER process. These merits make Fe-doped Co9S8@CoO an efficient and stable OER catalyst: it requires only a low overpotential of 296 mV to obtain 10 mA cm−2 and it delivers a low Tafel slope of 65 mV dec−1 with good stability, which are even better than those of commercial RuO2. This work presents an effective structural/electronic modulation strategy to develop efficient and stable OER catalysts for water splitting.

Monitoring and control of the release of soluble O2 from H2 O2 inside porous enzyme carrier for O2 supply to an immobilized d-amino acid oxidase.

While O2 substrate for bio‐transformations in bulk liquid is routinely provided from entrained air or O2 gas, tailored solutions of O2 supply are required when the bio‐catalysis happens spatially confined to the microstructure of a solid support. Release of soluble O2 from H2O2 by catalase is promising, but spatiotemporal control of the process is challenging to achieve. Here, we show monitoring and control by optical sensing within a porous carrier of the soluble O2 formed by an immobilized catalase upon feeding of H2O2. The internally released O2 is used to drive the reaction of d‐amino acid oxidase (oxidation of d‐methionine) that is co‐immobilized with the catalase in the same carrier. The H2O2 is supplied in portions at properly timed intervals, or continuously at controlled flow rate, to balance the O2 production and consumption inside the carrier so as to maintain the internal O2 concentration in the range of 100–500 µM. Thus, enzyme inactivation by excess H2O2 is prevented and gas formation from the released O2 is avoided at the same time. The reaction rate of the co‐immobilized enzyme preparation is shown to depend linearly on the internal O2 concentration up to the air‐saturated level. Conversions at a 200 ml scale using varied H2O2 feed rate (0.04–0.18 mmol/min) give the equivalent production rate from d‐methionine (200 mM) and achieve rate enhancement by ∼1.55‐fold compared to the same oxidase reaction under bubble aeration. Collectively, these results show an integrated strategy of biomolecular engineering for tightly controlled supply of O2 substrate from H2O2 into carrier‐immobilized enzymes. By addressing limitations of O2 supply via gas‐liquid transfer, especially at the microscale, this can be generally useful to develop specialized process strategies for O2‐dependent biocatalytic reactions.

Formulation and Evaluation of Isradipine Nanosuspension and Exploring its Role as a Potential Anticancer Drug by Computational Approach.

T-type calcium channels are aberrantly expressed in different human cancers and regulate cell cycle progression, proliferation, migration, and survival. FAK-1 can promote tumor protein degradation (p53) through ubiquitination, leading to cancer cell growth and proliferation. Similar findings are obtained regarding protease inhibitors' effect on cytokine-induced neutrophil activation that suppresses Granulocyte-macrophage colony-stimulatingfactor (GM-CSF) TNF-α-induced O2 release and adherence in human neutrophils without affecting phosphorylation of Extracellular signal-regulated kinase (ERK) and p38. Nanosuspensions are carrier-free, submicron colloidal dispersions, which consist of pure drugs and stabilizers. Incorporating drug loaded in nanosuspensions offer a great advantages of passive drug targeting with improved solubility, stability, and bioavailability, as well as lower systemic toxicity. The present investigation objective was to establish a molecular association of Protease and Focal Adhesion Kinase 1 as cancer targets for isradipine, a calcium channel blocker (CCB). Furthermore, the study also aimed to formulate its optimized nanosuspension and how the physical, morphological, and dissolution properties of isradipine impact nanosuspension stability. Five different molecular targets, namely Cysteine Proteases (Cathepsin B), Serine Proteases (Matriptase), Aspartate Proteases, Matrix Metalloproteases (MMP), and FAK-1 were obtained from RCSB-PDB, which has some potential associations with inhibition in cancer pathogenesis. Molecular interactions of these targets with CCB isradipine were identified and established by molecular simulation docking studies. Isradipine-loaded nanosuspension was prepared by precipitation technique by employing a 23 factorial design. PVP K-30, poloxamer 188, and sodium lauryl sulfate (SLS) were used as polymer, co-polymer, and surfactant, respectively. The nanosuspension particles were assessed for particle size, zeta potential, viscosity, polydispersity index (PDI), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), In-vitro drug release kinetics, and short-term stability study. Considerable interactions were found with Cysteine, Serine, Aspartate, Threonine, and Matrix metalloproteases with binding energies of -3.91, -6.7, -3.48, -8.42, respectively. Furthermore, the interaction of isradipine with FAK-1 was compared with 7 native ligands and was found to show significant interaction with binding energies of - 8.62, -7.27, -7.69, -5.67, -5.41, -7.44, -8.21, respectively. The optimized nanosuspension was evaluated and exhibited a particle size of 754.9 nm, zeta potential of 32.5 mV, viscosity of 1.287 cp, and PDI of 1.000. The In-vitro dissolution of the optimized formulation (F8) was found to be higher (96.57%) as compared to other formulations. Isradipine could act as a potential inhibitor of different proteases and FAK-1 associated with tumor growth initiation, progression, and metastasis. Furthermore, isradipine-loaded nanosuspension with optimized release could be utilized to deliver the anticancer drug in a more targeted way as emerging cancer nanotechnology.

Stabilizing the Anionic Redox in 4.6 V LiCoO2 Cathode through Adjusting Oxygen Magnetic Moment

AbstractThe irreversible oxygen redox and the resulting structure degradation of LiCoO2 at a high voltage cause very poor cycling performance. Herein, the anionic redox chemistry in 4.6 V LiCoO2 cathode material through manipulating the oxygen magnetic moment (OMM) with oxygen vacancy and V doping is proposed to stabilize, and the relationship between OMM and the oxidation degree of oxygen is revealed. Oxygen vacancy induces the generation of OMM, and the synergy of oxygen vacancy and V doping reduces the change of OMM during charge/discharge processes. This mitigates the oxidation degree of oxygen and improves the reversibility of oxygen redox, which greatly inhibits the irreversible oxygen escape. The oxygen vacancies can further reduce the overlap of the electron clouds and lower the O 2p band center thus decreasing the oxygen redox activity. Moreover, the introduced V also increases the energy barrier of the phase transition and suppresses the irreversible phase transition and Co migration. The irreversible O2 release is significantly inhibited and the cycling stability at 4.6 V is largely enhanced. This study presents the relationship between OMM and the oxidation degree of oxygen and provides some insights into improving the anion redox reversibility through adjusting the oxygen magnetic moment.

Exploring the Origin of Anionic Redox Activity in Super Li-Rich Iron Oxide-Based High-Energy-Density Cathode Materials

Super alkali-rich materials (alkali:transition metal ratio of ≥2:1), such as Li5FeO4, exhibit the potential to realize anionic redox upon deep delithiation. Li5FeO4 was shown to undergo reversible cycling between Li4FeO3.5 and Li3FeO3.5 with combined cation/anion redox, a remarkable capacity of 189 mAh/g, and no O2 release. However, the impact of phase transformations on the reaction thermodynamics and the correlation between the structural changes and reaction reversibility remain unclear. In this study, we use first-principles calculations to examine the delithiation and (re)lithiation reactions of Li5FeO4. We show that the experimentally observed charge and discharge processes go through non-equilibrium pathways. Upon delithiation, the compound undergoes a phase transformation from Li5FeO4, with tetrahedrally coordinated (Td) Fe ions, to a delithiated disordered rocksalt structure, with octahedral (Oh) Fe ions. Fe-ion migration has an asymmetric kinetic barrier that makes Td → Oh migration facile, whereas the reverse process has a much larger barrier, explaining the difficulties in reaction reversibility. We further elucidate the transition metal and O redox sequences during the charge cycle and identify the complex electrochemistry associated with the dual participation of cationic redox (Fe3+/Fe4+) and anionic redox (O2–/O–/O0). Armed with this knowledge, we conduct high-throughput screening of known alkali-rich transition metal oxides by evaluating their potential to enable reversible anionic redox, with multiple candidates proposed for further experimental trials. Our work provides a useful guide for the further development of super alkali-rich anionic-redox-active electrodes for high-energy-density batteries.

Regulation of Mitochondrial Calcium Transport by Caloric Restriction in Rat Kidney

Caloric restriction (CR) in laboratory rodents prevents obesity, promotes healthy aging, and increases resilience against several pathological stimuli. At the mitochondrial level, protection promoted by CR in the brain and liver is related to higher calcium uptake rates and retention capacity, preventing Ca2+‐induced mitochondrial permeability transition. Dietary restriction has been demonstrated to increase kidney resistance against damaging stimuli such as ischemia/reperfusion, but if these effects are related to similar mitochondrial adaptations had not yet been uncovered. Here, we characterized changes in mitochondrial function in response to six months of CR in rats, measuring oxidative phosphorylation, redox balance and calcium homeostasis. CR promoted an increase in mitochondrial oxygen consumption rates under non‐phosphorylating (state 4) and uncoupled (state 3U) conditions. While CR prevents mitochondrial reactive oxygen species production in many tissues, in kidney we found that mitochondrial H2O2 release was enhanced in CR rats, although levels of carbonylated proteins and methionine sulfoxide were unchanged. Surprisingly, and opposite to the effects observed in brain and liver, mitochondria from CR animals are more prone to Ca2+‐induced mitochondrial permeability transition. CR mitochondria also displayed higher calcium uptake rates, which were not accompanied by changes in calcium efflux rates, nor related to altered inner mitochondrial membrane potentials, or the amounts of the Mitochondrial Calcium Uniporter (MCU). Instead, increased mitochondrial calcium uptake rates correlate with a loss of Mitochondrial Calcium Uptake 2 (MICU2), an MCU modulator, in CR kidneys. Interestingly, MICU2 is also modulated by CR in liver, suggesting it has a broader diet‐sensitive regulatory role determining mitochondrial calcium homeostasis. Together, our results remark the highly organ‐specific bioenergetic, redox, and ionic transport effects of CR. Specifically, we describe the regulation of the expression of MICU2, and its effects on mitochondrial calcium transport, as a novel and interesting aspect of the metabolic responses to dietary interventions.

Myoglobin Interaction with Lactate Rapidly Releases Oxygen: Studies on Binding Thermodynamics, Spectroscopy, and Oxygen Kinetics.

Myoglobin (Mb)-mediated oxygen (O2) delivery and dissolved O2 in the cytosol are two major sources that support oxidative phosphorylation. During intense exercise, lactate (LAC) production is elevated in skeletal muscles as a consequence of insufficient intracellular O2 supply. The latter results in diminished mitochondrial oxidative metabolism and an increased reliance on nonoxidative pathways to generate ATP. Whether or not metabolites from these pathways impact Mb-O2 associations remains to be established. In the present study, we employed isothermal titration calorimetry, O2 kinetic studies, and UV-Vis spectroscopy to evaluate the LAC affinity toward Mb (oxy- and deoxy-Mb) and the effect of LAC on O2 release from oxy-Mb in varying pH conditions (pH 6.0–7.0). Our results show that LAC avidly binds to both oxy- and deoxy-Mb (only at acidic pH for the latter). Similarly, in the presence of LAC, increased release of O2 from oxy-Mb was detected. This suggests that with LAC binding to Mb, the structural conformation of the protein (near the heme center) might be altered, which concomitantly triggers the release of O2. Taken together, these novel findings support a mechanism where LAC acts as a regulator of O2 management in Mb-rich tissues and/or influences the putative signaling roles for oxy- and deoxy-Mb, especially under conditions of LAC accumulation and lactic acidosis.