Oxygen Species Research Articles

Modulating the chemical environment of Ni2+ for the oxidative dehydrogenation of ethane: The formation of LAS(Al3+/Ga3+)-Ni-OH site

The oxidative dehydrogenation of ethane to ethylene (ODHE) usually suffers from the issues of ethane conversion-ethylene selectivity seesaw. Herein, a series of alumina-supported Ni and Ga catalysts with different molar ratios of Ni to Ga were synthesized by facile impregnation method constructing the Lewis acid site (LAS) strategy to obtain great ethylene selectivity (97 %). The variation of Ni:Ga ratio adjusted the ionic substitution ability, redox ability and acidity, thus regulate the chemical environment of Ni2+ to the formation of LAS(Al3+/Ga3+)-Ni-OH structure, which was proposed to be the active site for selective oxidation of ethane to ethylene, as proved by H2-TPR, ToF-SIMS, quasi in-situ XPS and in-situ FTIR. Moreover, the probable mechanism of ODHE reaction was proposed that C2H6 molecules were mainly adsorbed on LAS sites and activated on Ni-OH site of the catalyst. The pulse test further suggested that O- was mainly associated with the generation of CO2 and Ni(2-n)+ was connected with the production of CH4. It is highlighted that adjusting the Ni-related species and oxygen species on the catalyst surface are crucial to further improve the ethylene selectivity.

Dopant effects on the environment-dependent chemical properties of NiO(100) surfaces

NiO is a promising material for applications such as electronic devices and catalysts due to its low cost, environmental friendliness, and optimal chemical and electronic properties. Inclusion of a dopant element into the NiO near surface structure can further tune material properties. Despite extensive studies on doped NiO (M−NiO) materials, there remains a lack of knowledge regarding the connection between dopant, environment-dependent dominant near surface structures, and overall chemical properties. Here, the dopant effects on the near surface structure and electronic properties on M−NiO(100) are systematically examined using a combination of density functional theory (DFT) and ab initio phase diagrams. The simultaneous factors tested include dopant element (Al, Mo, Nb, Sn, Ti, V, W, or Zr), dopant placement (surface or subsurface), Ni/O vacancies (surface or subsurface), and oxygen species (O* or O2*) adsorption. The results reveal the dominant structures and compositions of M−NiO(100) under a wide range of environmental conditions (i.e. varying temperature and pressure). Subsequent electronic analyses of the dominant M−NiO(100) structures shows non-uniform changes in charge redistribution, band gap, work function, and d-band center with dopant and near surface structure, emphasizing the role of dopants in tuning M−NiO(100) both geometric and electronic properties. Overall, these multiscale modeling results enable a rapid, effective, and a priori prediction of dominant M−NiO(100) structures with distinct chemical properties, crucial for guiding NiO-based materials design with enhanced performance for advanced electronics, energy storage, and catalytic systems.

The Interfacial Ni/Fe─O─Y Bonds Contribute to High-Efficiency Water Splitting.

Developing economical and efficient electrocatalysts is critical for hydrogen energy industrialization through water electrolysis. Herein, a novel dual-site synergistic NiFe/Y2O3 hybrid with abundant interfacial Ni/Fe─O─Y bonds is designed by density functional theory (DFT) simulations. In situ Raman spectra combined with DFT calculations reveal that the interfacial Ni/Fe─O─Y units greatly promote H2O dissociation and optimize the adsorption of both H* and oxygen species, achieving excellent activity and durability for hydrogen evolution reaction. As expected, NiFe/Y2O3 exhibits a low overpotential of 27 mV at 10 mA cm-2 and robust stability of over 200 h at 1000 mA cm-2, and also outstanding water splitting performance with a low cell voltage of 1.64 V at 100 mA cm-2, showing significant potential for real-world applications.

Thermal conductivity in modified sodium silicate glasses is governed by modal phase changes.

The thermal conductivity of glasses is well-known to be significantly harder to theoretically describe compared to crystalline materials. Because of this fact, the fundamental understanding of thermal conductivity in glasses remain extremely poor when moving beyond the case of simple glasses, e.g., glassy SiO2, and into so-called "modified" oxide glasses, that is, glasses where other oxides (e.g., alkali oxides) have been added to break up the network and alter, e.g., elastic and thermal properties. This lack of knowledge is apparent despite how modified glasses comprise the far majority of known glasses. In the present work, we study an archetypical series of sodium silicate [xNa2O-(100 - x)SiO2] glasses. Analyses of modal contributions reveal how increasing Na2O content induces increasing vibrational localization with a change of vibrations to be less ordered and a related general decrease in modal contributions to thermal conductivity. We find the vibrational phases (acoustic vs optical) of sodium vibrations to be relatively disordered compared to the network-forming silicon and oxygen species, explaining how increasing Na2O content decreases thermal conductivity. Our work sheds new light on the fundamentals of glassy heat transfer as well as the interplay between thermal conduction and modal characteristics in glasses.

Typical Pathological Process in Glutamate Neurotoxicity: the Role of Reactive Nitrogen and Oxygen Species

The disruption of major regulatory mechanisms of nerve cells can lead to glutamate neurotoxicity/excitotoxicity. This phenomenon most often occurs in hypoxia/ischemia, during inflammatory processes, activation of immune and autoimmune responses. Pathological changes in the brain in the early stages of diseases are nonspecific. The distinction between pathological change and physiological norm is small. These typical pathological processes are common with a variety of diseases. They may also occur in ischemic and hemorrhagic strokes. The main objective of this work was to analyze some physiological and cytochemical processes that are associated with the neurotransmitter glutamate, as well as with highly reactive and highly toxic compounds such as reactive nitrogen and oxygen species. Reactive nitrogen (•NO) and oxygen (•O2–) species can affect almost all major components of cells and subcellular structures. At low concentrations, they perform a regulatory function. Mechanism analysis of toxic effects of glutamate, reactive nitrogen and oxygen species was essential for the development of new methods of protection against the damaging effects of the said substances thereby using these methods in treatment of ischemic and hemorrhagic strokes.

Morphology and Wettability of Polystyrene film on QCM Sensor Caused by Oxygen Plasma with DC Bias

Surface wettability and morphology are important aspects of developing QCM sensors for chemical sensors and biosensors. The functionality and morphology of the sensitive coating on the sensor surface affect the sensor sensitivity and selectivity. Various materials and methods to improve the functionality and morphology of the sensor surface have been developed, one of which is plasma. Species and parameters of the generated plasma play an important role in the treatment. One parameter is the DC-bias voltage of RF plasma, which plays an important role in plasma generation and bombardment on the surface being modified. This work shows the effect of the DC bias of the 2 MHz RF plasma with oxygen species. Surface functionality and morphology modification of the polystyrene film on the QCM sensor was done by surface modification using oxygen plasma. Partial etching of the polystyrene film occurred when treated with oxygen plasma generated using 2 MHz with negative DC-bias. CII, CO+, and CO were detected during the exposure of oxygen plasma on polystyrene film, indicating a chemical reaction between the plasma species, oxygen plasma, and the polystyrene. Observation by optical microscope and SEM showed the occurrence of partial etching on the polystyrene film. As there is no masking, the partial etching occurred randomly. The average size of the etched film increased with the DC bias voltage, but the percentage of the etched area was not. The oxygen plasma converts the polystyrene film from hydrophobic to hydrophilic, but hydrophobicity increases with the DC bias voltage. HIGHLIGHTS Polystyrene surface treatment using oxygen plasma can be used to alter the surface hydrophobicity. The DC bias plays important role in the surface modification. High DCV bias gives stronger plasma energy which may etched the polystyrene film. Observation using SEM shows part of the polystyrene film was etched as the DC bias voltage increase. The amount of the etched surface can be measured using optical microscope and processed using ImageJ. Increasing the DC bias result in a wider etched film. GRAPHICAL ABSTRACT

Ethanolic extract of Parkia speciosa pods exhibits antioxidant and anti-inflammatory properties in lipopolysaccharide-induced murine macrophages by inhibiting the p38 MAPK pathway

BackgroundParkia speciosa (PS) is commonly used in Southeast Asian cuisine and traditional medicine to treat diabetes, hypertension, dermatitis, and kidney diseases. PS has emerged as a subject of interest because of its potential antioxidation and anti-inflammatory properties. However, despite its historically long and wide usage, a comprehensive investigation of these properties in PS pods (PSp) have not been conducted. Aims of this studyThis study aimed to identify the phytochemical compounds in the ethanolic extract of PSp collected from Southern Thailand and assess whether PSp exhibit antioxidant properties and mitigate inflammation in a lipopolysaccharide (LPS)-induced RAW264.7 model. Materials and methodsThe ethanolic extract of PSp was comprehensively analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC/MS) to identify its phytochemical constituents. To assess the antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) assays were performed, and cytotoxicity was evaluated using the MTT assay. The effect of PSp on reactive nitrogen and oxygen species (RNS and ROS) was determined using a nitric oxide (NO) assay, and its effect on pro-inflammatory cytokines was assessed using enzyme-linked immunosorbent assay (ELISA) and real-time quatitvative polymerase chain reaction (qPCR). Morphological changes following treatment were observed using a microscope. Western blot analysis was performed to quantify MAPK pathway expression. ResultsPSp contain polyphenols, phytosterols, triterpenes, oxaloacetic acid, and unsaturated fatty acids. PSp demonstrated high antioxidant potential in scavenging free radicals and exhibited no cytotoxic effects on macrophages. Moreover, PSp effectively reduced NO release and inhibited pro-inflammatory cytokines such as IL1-β, TNF-α, and IL-6. PSp treatment induced notable morphological changes in macrophages, characterized by an increase in cell size and the presence of intracellular vacuoles. In addition, Western blot analysis showed the selective suppressive effect of PSp on the p38-MAPK pathway. ConclusionPSp possess strong antioxidant and anti-inflammatory properties, making it a potential therapeutic agent for the treatment of inflammatory disorders.

Role of Nrf2 in Epilepsy Treatment.

Oxidative stress is a consequence of the disruption of the balance between the generation of reactive nitrogen and oxygen species and the biological system's ability to neutralize those reactive products. Oxidative stress is involved in the generation of many disorders, including epilepsy, which is a prevalent chronic neurological disease that affects the lives of millions of people around the world. Epilepsy is characterized by unforeseeable and repeated seizures that can be very disturbing. Studies have reported that oxidative stress occurs before and after seizures. A transcription factor named Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) controls genes related to the induction of oxidative stress and defends cells against oxidative stress. The Nrf2 protein has seven different domains, ranging from Neh1 to Neh7. Each domain is responsible for a distinctive function of this protein. Keap1 binds to Nrf2, but during oxidative stress, Nrf2 detaches from the Keap1 protein, moves to the nucleus, and binds to DNA. The result of this translocation and binding is the initiation of transcription of detoxifying genes to control the harmful effects of oxidative stress. There is some evidence of oxidative stress involvement in epilepsy. In this review, we have listed potential Nrf2-related therapeutic targets for treating and controlling epilepsy, such as Berberis alkaloids, pentoxifylline, lovastatin, progesterone, and chrysin nanoparticles. These activators were tested in animals (in vivo) and cells (in vitro), and most of these experiments showed promising results in different epilepsy models. Finally, the results have suggested that the activation of Nrf2 can be an option for controlling epilepsy.

Main-group element-boosted oxygen electrocatalysis of Cu-N-C sites for zinc-air battery with cycling over 5000 h

Developing highly active and durable air cathode catalysts is crucial yet challenging for rechargeable zinc-air batteries. Herein, a size-adjustable, flexible, and self-standing carbon membrane catalyst encapsulating adjacent Cu/Na dual-atom sites is prepared using a solution blow spinning technique combined with a pyrolysis strategy. The intrinsic activity of the Cu-N4 site is boosted by the neighboring Na-containing functional group, which enhances O2 adsorption and optimizes the rate-determining step of O2 activation (*O2 → *OOH) during the oxygen reduction reaction process. Meanwhile, the Cu-N4 sites are encapsulated within carbon nanofibers and anchored by the carbon matrix to form a C2-Cu-N4 configuration, thereby reinforcing the stability of the Cu centers. Moreover, the introduction of Na-containing functional groups on the carbon atoms significantly reduces the positive charge on their outer shell C atoms, rendering the carbon skeletons less susceptible to corrosion by oxygen species and further preventing the dissolution of Cu centers. Under these multi-type regulations, the zinc-air battery with Cu/Na-carbon membrane catalyst as the air cathode demonstrates long-term discharge/charge cycle stability of over 5000 h. This considerable stability improvement represents a critical step towards developing Cu-N4 active sites modified with the neighboring main-group metal-containing functional groups to overcome the durability barriers of zinc-air batteries for future practical applications.

Analysis of Intact In Vivo Peroxidized Phospholipids from Bovine Retina via LC-MS/MS and GC-MS/MS Using Autoxidized Retina Reference Standards.

Highly unsaturated fatty acids (HUFAs) are vulnerable to oxygen attack, thus making HUFA-rich, high metabolic rate/reactive oxygen species (ROS)-generating neurological tissue particularly susceptible to increased oxidative stress. Lipid oxidation is a putative early stage marker of neurodegenerative diseases, suggesting that reliable monitoring of oxidized neural lipids in vivo reveals early pathogenesis. Here, we present a novel methodology to detect and quantify intactin vivo ROS-driven peroxidized phospholipids (LPOx-PLs) in bovine retina extract. A protocol for preparing autoxidized pure phospholipids (PLs) and complex retinal extracts served as reference standards and was adapted to enable analytical parameter development. Fatty acid profiles of bovine retinas were first established with routine gas chromatography (GC) methods and used to customize mass spectrometry scanning for major HUFA-carrying PLs in the retinal extract. Targeted multiple reaction monitoring (MRM) scanning via triple quadrupole tandem mass spectrometry detected native (unoxidized) and oxidation-damaged PL regardless of the position of the O or O2 addition along the acyl chains and enabled quantification of relative signals from intact native and oxidized PL (5%-10% CV). MRM-triggered information-dependent acquisition (IDA) spectra confirmed the structure of peroxidized PLs, revealing that peroxidized species (+O-OH) dominated over single O-added species in vitro and in vivo. Positive identification and relative quantification are reported for 12 selected in vivo native and peroxidized phosphatidylcholines and phosphatidylethanolamines. These results enable future studies of the initial peroxidation due to toxins, genetics, or other initiating events influencing in vivo oxidation levels and potentially the effectiveness of strategies to mitigate this mechanism of action.

Enhanced 3D electrochemical degradation of acrylonitrile with Fe-Cu@CB nanoparticles via the hydrogenation-oxidation synergistic processes

Acrylonitrile is a highly toxic and hazardous pollutant present in industrial wastewater at high concentrations, posing significant environmental and health risks. There is an urgent need for efficient, cost-effective, and environmentally friendly treatment methods for acrylonitrile. The electron-withdrawing –CN group in acrylonitrile offers potential pathways for degradation via superoxide radicals (O2•-), but this approach remains underexplored with limited research efforts. To investigate the degradation mechanism of acrylonitrile by O2•-, we synthesized particle electrodes Fe-Cu@CB using a novel one-step co-hydrolysis method and applied them for the 3D electrochemical degradation of acrylonitrile. Batch experiments showed that acrylonitrile with an initial concentration of 100 mg·L−1 was removed by 95 % at a voltage of 2.73 V (vs. RHE) for one hour. Compared with 2D electrochemical degradation, 3D electrochemical degradation of acrylonitrile increased the removal rate from 57 % to 95 %, and the TOC removal rate was also enhanced from 23.59 % to 88.33 %. Additionally, the energy consumed by this system was remarkably lower than the reported 3D electronic reaction system. Based on electron paramagnetic resonance (EPR), oxygen species (ROS) quenching experiments, and GC–MS results, we proposed a new hydrogenation-oxidation synergistic pathway for acrylonitrile removal, which could be depicted as that acrylonitrile suffered hydrogenation, followed by O2•- reduction, and finally the intermediate products were degraded speedily. Other pollutants in acrylonitrile wastewater such as acrylic acid, acrylamide, and fumaronitrile could also be eliminated in this reaction system, and the degradation efficiency varied with the electronic structure of the pollutants. These findings offer new insights into the treatment of acrylonitrile wastewater and present a highly efficient, sustainable solution for industrial pollutant degradation.

Active and stable Ni-Cr oxide catalysts for oxidative dehydrogenation of ethane using CO2: Carbon cycle-assisted oxygen cycle

The CO2-assisted oxidative dehydrogenation of ethane (CO2-ODHE) is known as an ecologically beneficial process for ethylene generation and CO2 utilization. However, the quick deactivation of traditional Cr-based catalysts remains a considerable challenge. Herein, we report that a 1Ni1CrOx/ZrO2 catalyst could be high active and stable for the CO2-ODHE reaction; it showed CO2 conversion of 15.4 % and kept stable for 38 h at 600 °C, while the productivity of ethylene approached 325 μmol·min−1·gcat−1. Kinetic evaluations found a low apparent activation energy of 87.2 kJ/mol on the 1Ni1CrOx/ZrO2 catalyst. Surface Cr6+ and oxygen species were enriched to form Cr2O72− with the introduction of NiO. In addition, NiO improved the surface alkalinity and the affinity for oxygen, promoting the strong adsorption and easy activation of CO2. Importantly, Niδ+ species catalyzed the reaction between CO2 and surface-deposited carbon by redox cycling (carbon cycle), promoting Mars-van Krevelen-type carbon elimination and Cr6+ regeneration. The carbon cycle-assisted oxygen cycle on the Ni-Cr oxide catalysts could obviously enhance the carbon resistance and stable ethylene production, demonstrating potential application of Cr-based catalysts for CO2-ODHE reaction.

Depletion of monocytic myeloid-derived suppressor cells in LP-BM5 murine retroviral infection has a positive impact on virus-induced host immunodeficiency

We have shown the induction of CD11b+Ly6C+ monocytic myeloid-derived suppressor cells (M-MDSCs) during infection of B6 mice by LP-BM5 immunodeficiency-inducing retrovirus. We published that the molecular mechanisms of these M-MDSCs vary, and depend on the cell type targeted by the suppression –defined by use of biochemical inhibitors, mouse M-MDSCs knock-out strains and blocking antibodies. These M-MDSCs suppressed proliferation and function of T cells, via nitric oxide synthase/nitric oxide; and that of B cells, ∼50% via INOS/NO along with the negative checkpoint regulator VISTA, reactive nitrogen and oxygen species, and other soluble mediators. Here, LP-BM5 infected mice were treated weekly with 5-Fluorouracil (5-FU), resulting in depletion of peripheral blood and splenic M-MDSCs, reduced MDSC activity, and significantly decreased standard disease parameters of: splenomegaly, impaired B-and T-cell ex vivo polyclonal responses, and viral load. In addition, 5-FU treatment significantly increased percentages of CD4+ and CD8+ T cells.

Mixed-charge hyperbranched polymer nanoparticles with selective antibacterial action for fighting antimicrobial resistance

The escalating menace of antimicrobial resistance (AMR) presents a profound global threat to life and assets. However, the incapacity of metal ions/reactive oxygen species (ROS) or the indiscriminate intrinsic interaction of cationic groups to distinguish between bacteria and mammalian cells undermines the essential selectivity required in these nanomaterials for an ideal antimicrobial agent. Hence, we devised and synthesized a range of biocompatible mixed-charge hyperbranched polymer nanoparticles (MCHPNs) incorporating cationic, anionic, and neutral alkyl groups to effectively combat multidrug-resistant bacteria and mitigate AMR. This outcome stemmed from the structural, antibacterial activity, and biocompatibility analysis of seven MCHPNs, among which MCHPN7, with a ratio of cationic groups, anionic groups, and long alkyl chains at 27:59:14, emerged as the lead candidate. Importantly, owing to inherent differences in membrane potential among diverse species, alongside its nano-size (6 - 15 nm) and high hydrophilicity (Kow = 0.04), MCHPN7 exhibited exceptional selective bactericidal effects over mammalian cells (selectivity index > 564) in vitro and in vivo. By inducing physical membrane disruption, MCHPN7 effectively eradicated antibiotic-resistant bacteria and significantly delayed the emergence of bacterial resistance. Utilized as a coating, MCHPN7 endowed initially inert surfaces with the ability to impede biofilm formation and mitigate infection-related immune responses in mouse models. This research heralds the advent of biocompatible polymer nanoparticles and harbors significant implications in our ongoing combat against AMR. Statement of SignificanceThe escalating prevalence of antimicrobial resistance (AMR) has been acknowledged as one of the most significant threats to global health.Therefore, a series of mixed-charge hyperbranched polymer nanoparticles (MCHPNs) with selective antibacterial action were designed and synthesized. Owing to inherent differences in membrane potential among diverse species and high hydrophilicity (Kow = 0.04), the optimal nanoparticles exhibited exceptional selective bactericidal effects over mammalian cells (selectivity index >564) and significantly delayed the emergence of bacterial resistance. Importantly, they endowed surfaces with the ability to impede biofilm formation and mitigate infection-related immune responses.Furthermore, the above findings focus on addressing the problem of AMR in Post-Pandemic, which will for sure attract attention from both academic and industry research.

Taxifolin-iron nanozymes with excellent RONS scavenging ability for alleviating ethanol-induced gastric ulcer

Gastric ulcer, a chronic disease of the digestive system, presents a high incidence rate and poses significant health risks. It is closely associated with the excessive production of reactive nitrogen and oxygen species (RONS), inflammation and cell apoptosis. In this study, taxifolin (Tax)-iron nanozymes (Fe-Tax) was developed by conjugating Tax with iron ions (Fe3+), which exhibited the activities of catalase and superoxide dismutase in the gastrointestinal environment. Our results revealed that Fe-Tax nanozymes effectively scavenge RONS, mitigate oxidative damage, inflammation and cell apoptosis in vitro. Additionally, Fe-Tax could alleviate tissue inflammation and gastric mucosal damage by regulating NRF2, NF-κB, Bax/Bcl-2, and VEGF signal pathways in gastric ulcer ethanol-induced. Crucially, the Fe-Tax has been shown to have excellent biocompatibility in vitro and in vivo. Overall, this study developed Fe-Tax nanozymes with enzyme cascade reactions and provided a highly efficient strategy to prevent and alleviate gastric ulcers.

Multifunctional and immunoregulatory microenvironment-responsive hydrogel for whole course management of infected diabetic wounds

Infective diabetic wounds can significantly delay healing and pose severe infection risks. The process of infective diabetic wounds healing (DWH) are not only re-epithelialization and angiogenesis but also anti-bacterial, hair follicles regeneration and nerve growth. In this study, a stable dynamic hydrogel system was formulated by incorporating dynamic borate easter bond and carbon–carbon double bond, which based on tannic acid (TA) − acrylic phenyl boric acid (APBA) and acrylamide (AM). Subsequently, a hydrogel (ATAN-Met) was obtained by modifying the antibacterial ammonium cationic (N+) and loading metformin (Met). This system demonstrated impressive wet adhesion, self-healing, wearable and peelable properties, responding to glucose/reactive oxygen species (ROS) for drug release. In vitro and vivo experiments illustrated that ATAN-Met recruited mesenchymal stem cell (MSC), facilitating interaction between MSC and neural cells, regulating macrophage polarization, and modulating the diabetic wound microenvironment while exhibiting anti-bacterial property, ultimately leading to re-epithelialization and neurovascular-hair follicles regeneration. RNA and metabolomic sequencing indicated that ATAN-Met activate the Hippo pathway, inhibit the TNF pathway, and regulate wound metabolism to improve the diabetic wound microenvironment. These results suggest that the microenvironment-responsive ATAN-Met hydrogel shows considerable potential for the whole course management of infective DWH.

Optimal formulation of bitter gourd and black galingale extract: Evaluation of effects on inflammation and oxidative stress-related genes

Reactive nitrogen and oxygen species (RNOS) are defined as highly reactive molecules that can be generated endogenously and exogenously. The overproduction of RNOS leads to inflammation, neurodegenerative diseases, diabetes, obesity, and cancer. Natural antioxidants derived from plants are molecules that can neutralize those RNOS. In this study, to increase the antioxidant capacity in neutralizing RNOS, an in vitro evaluation of a binary combination of bitter gourd (Momordica charantia L.) and black galingale (Kaempferia parviflora) extracts as potential natural antioxidant sources at different ratios was conducted. A combination at the ratio of 1:6 showed the highest total phenolic content (TPC) (336.48 ± 0.04 mg GAE/100g DW), while the ratios 1:6 (1511.73 ± 0.20 mg QE/100g DW) and 1:8 (1398.91 ± 0.28 mg QE/100g DW) exhibited the highest total flavonoid content (TFC) compared to the bitter gourd extract and other mixed ratios. The highest scavenging capacities in the DPPH, ABTS, and FRAP assays were detected at the ratios of 1:3 (IC50 9.1 ± 0.07 mg/mL; moderate synergism), 1:6 (IC50 1.07 ± 0.07 mg/mL; synergism), and 1:4 (IC50 2.44 ± 0.04 mg/mL; strong synergism), respectively. Based on the overall cumulative ability to scavenge free radicals with synergistic or additive antioxidant interactions and the presence of functional groups analyzed using FT-IR, the 1:6 ratio was determined as the best combination ratio to neutralize RNOS where 15 proposed beneficial bioactive compounds were detected. Additionally, in vivo studies showed that the increase of CAT mRNA expression and the suppression of NF-kB and CPT-1 mRNA expression at 250 mg/kg BW of dosage confirms that this methanolic mixed extract potentially can effectively act as both an anti-inflammation and antioxidant agent. This study demonstrates that a specific binary combination ratio of plant extracts can synergistically and additively increase their antioxidant capacity, even when utilized in small quantities.

Microbubble-enhanced cold plasma activation (MB-CPA) for surface functionalization of polymer nanoparticles from nanoprecipitation

Cold plasma activation has been considered as a green and effective technological approach for functionalization of solid surfaces. In the current study, we introduce a versatile technique known as microbubble-enhanced cold plasma activation (MB-CPA) for surface modification of polymer plates and nanoparticles in flowing liquid phase. Corona plasma is generated at the inlet of a venturi tube, thereby creating a highly excited state in the air. Reactive nitrogen and oxygen species (RNOS) are transferred from the gas phase to the suspension flow in the form of plasma microbubbles. Two types of polymer-based nanoparticles in the suspension, namely polymethyl methacrylate (PMMA) of 16–154 nm and polycaprolactone (PCL) of 30–225 nm, are synthesized using nano-precipitation method. Through the degradation of model compounds, the polar organic solvent, acetone and ethanol, is found to promote or suppress the production of active species. In addition, the efficiency of the MB-CPA treatment depends on the solvent composition, making this technology a controllable and efficient strategy for the surface modification of nanoparticles. The findings indicate that plasma activation effectively reduces the negative surface zeta-potentials and induces aggregation and separation in the suspensions. The infrared spectra of the treated nanoparticles reveal that plasma activation leads to the formation of NH and CN bonds situated on the surface of PMMA. Our work demonstrates that organic-solvent involved MB-CPA emerges as a promising method for the surface modification of nanoparticles in the flow condition.

Near-Ambient Pressure Oxidation of Silver in the Presence of Steps: Electrophilic Oxygen and Sulfur Impurities.

The oxidation of Ag crystal surfaces has recently triggered strong controversies around the presence of sulfur impurities that may catalyze reactions, such as the alkene epoxidations, especially the ethylene epoxidation. A fundamental challenge to achieve a clear understanding is the variety of procedures and setups involved as well as the particular history of each sample. Especially, for the often-used X-ray photoemission technique, product detection, or photoemission peak position overlap are problematic. Here we investigate the oxidation of the Ag(111) surface and its vicinal crystal planes simultaneously, using a curved crystal sample and in situ X-ray photoelectron spectroscopy at 1 mbar O2 near-ambient pressure conditions to further investigate surface species. The curved geometry allows a straightforward comparative analysis of the surface oxidation kinetics at different crystal facets, so as to precisely correlate the evolution of different oxygen species, namely nucleophilic and electrophilic oxygen, and the buildup of sulfur as a function of the crystal orientation. We observed that emission from both surface and bulk oxide contributes to the characteristic nucleophilic oxygen core-level peak, which arises during oxygen dosing and rapidly saturates below temperatures of 180 °C. The electrophilic oxygen peak appears later, growing at a slower but constant rate, at the expenses of the surface oxide. Electrophilic oxygen and sulfur core-levels evolve in parallel in all crystal facets, although faster and stronger at vicinal surfaces featuring B-type steps with {111} microfacets. Our study confirms the intimate connection of the electrophilic species with the formation of adsorbed SO4, and points to a higher catalytic activity of B-type stepped silver surfaces for alkene epoxidation or methane to formaldehyde conversion.

The Role of Surface Oxygen in Eliminating Fluorine Impurities and Relithiation Towards Direct Cathode Recycling

Recycling materials back to supply chain not only mitigates the shortage of critical materials such as the metals of Li, Ni, Co, etc, but also protects global environment. Direct recycling of lithium nickel manganese cobalt oxides (NMC) mainly relies on a relithiation process based on purified spent NMC cathode materials. How to efficiently get rid of chemically bonded surface impurities on spent NMC and obtain a clean surface is critical for relithiation. One of the unavoidable impurities is fluorine, which exists in the form of either carbon fluoride (CFx) or metal fluoride (M-F) and can be eliminated by either thermal treatment or hydrothermal procedure under alkaline environments depending on the state of the F.1,2 Generally the hydrothermal method needs relative high temperature (> 200 °C ) and long reaction time (> 16 hours) due to the slow kinetics. A redox mediator such as H2O2, ethanol or ethylene glycol has been reported to be effective to lower the temperature and pressure for relithiation of recycled NMC111 and NMC622, which was pretreated with N-Methyl-2-pyrrolidone solvent.3 However the mechanism is still not fully understood.This work combines material characterizations and electrochemistry and density functional theory (DFT) calculations to study the role of surface oxygen in eliminating fluorine species on recycled NMC532 cathode material. The recycled NMC532 powders were separated from graphite by froth flotation method and there were significant amount of fluorine impurity species on the surface confirmed by XPS. Initial trial of the addition of small amount of H2O2 additive to LiOH aqueous solution during the hydrothermal process was able to decrease the reaction time significantly to fully eliminate both CFx and M-F species compared to the reaction without H2O2. Further calcination steps with the addition of 5% excessive lithium source using LiOH successfully recovered the recycled NMC532 and the half coin cell using the rejuvenated cathode materials shows a discharge capacity of 154 mAh/g at 0.2 C within 2.7 to 4.2 V voltage range. DFT calculations was conducted on a NMC (012) surface and both lithium hydroxide and sodium hydroxide were selected to understand the role of OH- group and surface oxygen species. The kinetics study was conducted with transition state theory4 and the activation energy barriers were calculated by climbing image nudged elastic band (cNEB) method.5,6 The removal of surface F- takes place with the displacement of F- with OH- (*-(M)F(s) +XOH(s) à XF(s) + *-(M)OH(s), X= Li, Na). F- displacement reactions require more than one basic molecule per F- removal with the formation of either LiF or NaF, which is soluble in water and can be removed by a filtration process. Depending on the surface ‘foreign’ oxygen species, the reaction can either go with a hydroxide pathway or a peroxide pathway, with the latter involving the formation of a peroxide intermediate with a ‘foreign’ oxygen atom leading to much smaller barrier energy compared to that in the hydroxide pathway. On a delithiated surface, the barrier energy for F- removal is predicted to be higher than pristine surfaces as the delithiated surface is less reactive to bind ‘foreign’ oxygen. This is consistent with the experimental results in which the additive of H2O2 can provide ‘foreign’ oxygen atoms and favors peroxide pathway leading to shorter time to remove surface fluorine. Additionally, the reaction with NaOH has a lower barrier than that with LiOH for the removal of fluoride species. Future work will investigate alternative additives as well as fluorine surface-bulk transfer which potentially happen if small amount of fluorine residues exist during calcination step.