Excess O2 Research Articles

The Catalytic Mechanisms and Design Strategies of Noble Metal Catalysts for Selective Reduction of NOx with CO

AbstractThe selective catalytic reduction of NOx by CO (CO‐SCR) is a viable method for simultaneously mitigating NOx and CO emissions in motor vehicle exhaust and industrial flue gases. Extensive research has been conducted on noble metal catalysts because of their superior catalytic activity and stability compared to non‐noble metals. Noble metal catalysts demonstrate efficient NOx conversion and high selectivity for N2. However, achieving high conversion, selectivity, and stability over a wide temperature range in the presence of excess O2, H2O, and SO2 remains a significant challenge. This review summarizes recent advancements in CO‐SCR over noble metal catalysts, providing insights for the development of CO‐SCR catalysts. This paper first examines the reaction mechanisms of CO‐SCR, followed by a discussion on the design and optimization strategies of noble metal catalysts, with a focus on composition and structural effects. This includes creating active metal sites, selecting appropriate supports, integrating catalytic additives, choosing monometallic nanoparticles, alloying, and using single‐atom catalysts. Finally, remaining challenges and potential avenues for future research have been suggested. The discovery of negatively charged noble metal single‐atom‐site catalysts presents new research opportunities.

Coke evolution study in a liquid atomization into gas-solid fluidized bed to convert fructose to value-added chemicals

Glucose and fructose are valuable compounds, which have the potential to displace fossil fuels as a feedstock for highly valued products. One of the promising reactions is the oxi-dehydration of fructose to produce Hydroxymethylfurfural, 2,5-diformylfuran, and furfural. Current processes to produce platform chemicals like Hydroxymethylfurfural, furfural, and 2,5-diformylfuran operate in liquid phase with homogeneous heterogeneous catalyst, but commercialization is limited by scale and environmental impact of the large volume solvent required. Here we developed a gas-phase process to convert fructose in a fluidized bed reactor over Mo − V − WO3/TiO2. However, in the catalytic oxi-dehydration of fructose, coke forms on active sites and decreases conversion but increases selectivity. Coke and reactor performance depends on fructose concentration and O2/fructose ratio. In the first 2 h, acidic amorphous coke accumulates (based on TPO, FTIR, and UV–vis). Feeding excess O2 maintains coke in an amorphous structure and liberates oxide sites. Whereas coke promotes, water block active site reducing yield. In this work, we optimized the operating parameters of fructose concentration (%) and O2/fructose ratio, while simultaneously mitigating the issues associated with coke formation and its detrimental effects.

Influence of O2 content on surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet to improve surface flashover strength

In order to improve the surface flashover strength of the insulation materials and solve the problem that the relatively high price of CF4 restricts the large-scale application of fluorination modification of CF4 atmospheric pressure plasma jet (APPJ) in the industrial field, He/CF4/O2 APPJ with different O2 content is used to treat epoxy resin (EP) dielectric material. By analyzing the results of scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy, the influence of O2 content on the multiple characteristics of EP surface before and after APPJ treatment is studied. Flashover experiment is also carried out on EP surface before and after APPJ treatment. It is found that the addition of 0.1% O2 can increase the mature voltage of the EP surface by about 16.10% compared with untreated EP surface. It is concluded that the improvement of the surface flashover strength with a small amount of O2 (within 0.1%) is influenced by the surface roughness and chemical composition of the dielectric. The deposition effect of APPJ on EP surface is enhanced to increase the surface roughness and reaches the best at 0.1% O2, because the addition of excessive O2 will weaken the APPJ intensity. It is speculated that the creepage distance of the EP surface is increased to inhibit the formation of electron collapse and the content of electronegative fluorine and oxygen on the EP surface is increased under a small amount of O2 addition, resulting in the inhibition of the formation of surface flashover.

Synthesis and Aerobic Oxidation of Perfluoroalkyl d10 Metal Complexes Supported by 2,7‐Dimethyl‐1,8‐Naphthyridine

AbstractThe coordination chemistry of 2,7‐dimethyl‐1,8‐naphthyridine has been explored with perfluoroalkyl d10 metals, CuI, ZnII, and AgI. This ligand was shown to form dicoordinate CuI and AgI mono‐perfluoroalkyl complexes where naphthyridine coordinates with only one N‐donor, while bidentate coordination with both N‐atoms was observed in Zn bis(perfluoroalkyl) complexes forming a strained four‐membered chelate ring. Copper complexes undergo facile oxidation in the presence of air or excess O2 to give tetracoordinate CuII complexes coordinated to perfluorocarboxylates formed by oxygenation of the metal‐adjacent α‐CF2 position of the corresponding perfluoroalkyl ligands. Another type of product formed by the oxidation of perfluoroethylcopper(I) complexes in the presence of substoichiometric O2 are binuclear CuI⋅⋅⋅CuI complexes with two perfluorocarboxylate ligands. In the presence of an external substrate, alkene, O‐atom transfer was observed to give oxygenated products, resembling the recently reported O‐transfer reactivity of naphthyridine‐supported Ni long‐chain perfluoroalkyl complexes.

Scatalysis: Exploring the mechanism of photocatalytic algal removal

Photocatalytic algal removal is an environmentally friendly and low-cost algal bloom control technology. In this work, carbon nitride nanosheets based on morphology control were synthesized, and a ternary Z-scheme photocatalyst was designed through heterojunction engineering for photocatalytic removal of harmful algae and their organic matter, and the removal rate of chlorophyll a was close to 100 % in 300 min. Three-dimensional fluorescence spectrograms and cellular SEM maps revealed the removal of algae and their organic matter, and the mechanism of Ag/AgCl/ZIF-8/SCN photocatalytic algal removal was explored in conjunction with the changes in membrane permeability and various physiological functions. Mechanistic studies showed that excess O2·− played a crucial role in cell inactivation and organic matter degradation. Oxidative stress caused by O2·− promoted the accumulation of H2O2 in cells and accelerates cell death. This study provides new ideas and support for the application of harmful algal bloom control and the mechanism of algal cell inactivation in real water bodies.

IrSn Bimetallic Clusters Confined in MFI Zeolites for CO Selective Catalytic Reduction of NOx in the Presence of Excess O2.

We developed a simple strategy for preparing IrSn bimetallic clusters encapsulated in pure silicon zeolites via a one-pot hydrothermal synthesis by using diethylamine as a stabilizing agent. A series of investigations verified that metal species have been confined successfully in the inner of MFI zeolites. IrSn bimetallic cluster catalysts were efficient for the CO selective catalytic reduction of NOx in the presence of excess O2. Furthermore, the 13CO temperature-programmed surface reaction results demonstrated that NO2 and N2O could form when most of the CO was transformed into CO2 and that Sn modification could passivate CO oxidation on the IrSn bimetallic clusters, leading to more reductants that could be used for NOx reduction at high temperatures. Furthermore, SO2 can also influence the NOx conversion by inhibiting the oxidation of CO. This study provides a new strategy for preparing efficient environmental catalysts with a high dispersion of metal species.

Efficiency of Boiler and Steam Turbine for Power Plant Unit 2 PT. XYZ

PT. XYZ has an electric power capacity of 70 MW and began operating in 2014 during its operation there has been a decrease in power from 35 MW at the time of commissioning to 32 MW. This study investigates the impact of the air-fuel ratio (AFR) on the efficiency of a thermal system, focusing on the boiler, turbine, and overall thermal cycle efficiency. Variations in excess O2 in flue gas were examined at levels of 5.0%, 5.5%, and 6.0%. The results reveal that the boiler efficiency peaks at 5.0% excess O2 (73.50%), while an increase in excess O2 or AFR leads to a decrease in efficiency. Turbine efficiency remains relatively stable (74-76%) despite a slight decline with increased AFR. The thermal cycle efficiency reaches its maximum at an AFR of 13.61 (45.60%) but diminishes at higher AFR values.

The behavior of pyrite during in-situ leaching of uranium by CO2 + O2: A case study of the Qianjiadian uranium deposit in the Songliao Basin, northeastern China

Oxidative weathering of pyrite, a widespread iron sulfide mineral, is crucial for the uranium mineralization in sandstone-hosted uranium deposits and the ore utilization leaching under manual intervention. To understand the behavior of pyrite under CO2 + O2 leaching conditions in sandstone-hosted uranium deposits, samples of uranium ore from the mineralized zone of the Qianjiadian IV uranium deposit located in the lower section of the Yaojia Formation were collected for this study. The stirring leaching experiment was carried out through the processes of the pyrite-bearing uranium ore samples thinned before and after the reaction, followed by an optical microscopic study and the TESCAN Integrated Mineral Analyzer analysis, and finally, the thermodynamic simulation by making use of PHREEQC3.0.The results revealed the following: (1) The dissolution particles of pyrite become smaller, which may increase the porosity of the ore layer and the exposure ratio of uranium minerals. And more soluble pyrite with a high free surface will be more competitive with uranium minerals for the consumption of O2. (2) The ion (Fe2+) produced by the dissolution of pyrite will be oxidized to Fe3+ by excess O2 (4 mol), which provides an oxidant for the oxidation of uranium minerals, and the generated SO42- will combine with the Ca2+ released from calcite to form a permanent precipitate of gypsum, which may block pores and cover the uranium ore. (3) Pyrite and calcite will consume O2 and CO2 in the injection system, thus jointly inhibiting the leaching of uranium minerals. After the injection of excessive CO2 and O2, the concentration of Ca2+, SO42-, Fe3+, UO22+, and HCO3– in the system will continue to accumulate, resulting in the secondary precipitation of calcite, co-precipitation of gypsum, iron minerals, colloids, and hexavalent uranium minerals, resulting in plugging pores and seriously affecting the effective leaching of uranium.This study contributes to the understanding of the behavior of pyrite during uranium recovery through CO2 + O2 leaching. It also contributes to the understanding of quantitative uranium mineralization in sandstone-hosted uranium deposits and process parameters in in-situ leaching (ISL) of uranium.

GABA attenuates neurotoxicity of zinc oxide nanoparticles due to oxidative stress via DAF-16/FoxO and SKN-1/Nrf2 pathways

Zinc oxide nanoparticles (ZnO-NPs) are one of the most widely used metal oxide nanomaterials. The increased use of ZnO-NPs has exacerbated environmental pollution and raised the risk of neurological disorders in organisms through food chains, and it is urgent to look for detoxification strategies. γ-Aminobutyric acid (GABA) is an inhibitory neurotransmitter that has been shown to have anxiolytic, anti-aging and inhibitory effects on nervous system excitability. However, there are few reports on the prevention and control of the toxicity of nano-metal ions by GABA. In zebrafish, ZnO-NPs exposure led to increased mortality and behavioral abnormalities of larva, which could be moderated by GABA intervention. Similar results were investigated in Caenorhabditis elegans, showing lifespan extension, abnormal locomotor frequency and behavior recovery when worms fed with GABA under ZnO-NPs exposure. Moreover, GABA enhanced antioxidant enzyme activities by upregulating the expression of antioxidant-related genes and thus scavenged excessive O2−. In the case of ZnO-NPs exposure, inhibition of nuclear translocation of DAF-16 and SKN-1 was restored by GABA. Meanwhile, the protective effect of GABA was blocked in daf-16 (−) and skn-1 (−) mutant, suggesting that DAF-16/FoxO and SKN-1/Nrf2 pathways is the key targets of GABA. This study provides a new solution for the application of GABA and mitigation of metal nanoparticle neurotoxicity.

An Insight in the Viscosity–Temperature Property of CaO‐SiO2‐Al2O3‐Based Slag Systems from Melt Structure

Viscosity is an important property for CaO‐SiO2‐Al2O3‐based slag systems, which showcases different scenarios in basic and acid slag systems with temperature change. This article elucidates the mechanism of their difference in viscosity–temperature property from melt structure. Results reveal that basic slag shows a low degree of polymerization (DOP) and a low viscosity of the melt due to an excessive O2− ions depolymerizing the complex network structures, resulting in more low‐polymerized Q0(Si) units and less high‐polymerized Q3(Si) units. With the temperature decreases, the DOP and viscosity do not change significantly. However, the low DOP and viscosity favor crystal precipitation in the melt, leading to a solid–liquid mixed state of the slag, and thus a sharp increase in viscosity when the temperature decreases to 1275 °C. For acid slag, it undergoes a transformation into aluminosilicate structures with the introduction of numerous [AlO4]5− tetrahedra, accompanied by a significant increase in the relative mole fraction of high‐polymerized Q3(Si) units. Consequently, the DOP and viscosity are obviously higher than that of the basic slag. Furthermore, the DOP and viscosity of the acid slag increase continuously with the temperature decreasing, thus impeding crystal precipitation and enhancing the glass transition tendency of the molten slag.

Improving the storage quality and suppressing off-flavor generation of winter jujube by precise micro-perforated MAP.

Traditional modified atmosphere packaging (MAP) cannot meet the preservation requirements of winter jujube, and the high respiration rate characteristics of winter jujube will produce an atmosphere component with high CO2 concentration in traditional MAP. Micro-perforated MAP is suitable for the preservation of winter jujube due to its high permeability, which can effectively remove excess CO2 and supply O2. In this study, a microporous film preservation system that can be quickly applied to winter jujube was developed, namely PMP-MAP (precise micro-perforated modified atmosphere packaging). An experiment was designed to store winter jujube in PMP-MAP at 20°C and 2°C, respectively. The quality, aroma and antioxidant capacity, etc. of winter jujube at the storage time were determined. In this study, the optimal micropore area required for microporous film packaging at different temperatures is first determined. To ensure the best perforation effect, the effects of various factors on perforation efficiency were studied. The gas composition within the package was predicted using the gas prediction equation to ensure that the gas composition of the perforated package achieved the desired target. Finally, storage experiments were designed to determine the quality index of winter jujube, including firmness, total soluble solids, titratable acid, reddening, and decay incidence. In addition, sensory evaluation, aroma and antioxidant capacity were also determined. Finally, the preservation effect of PMP-MAP for winter jujube was evaluated by combining the above indicators. At the end of storage, PMP-MAP reduced the respiration rate of winter jujube, which contributed to the preservation of high total soluble solids and titratable acid levels, and delayed the reddening and decay rate of winter jujube. In addition, PMP-MAP maintained the antioxidant capacity and flavor of winter jujube while inhibiting the occurrence of alcoholic fermentation and off-flavors. This can be attributed to the effective gas exchange facilitated by PMP-MAP, thereby preventing anaerobic stress and quality degradation. Therefore, the PMP-MAP approach is an efficient method for the storage of winter jujube.

Magneto-Conductive and Magnetic Properties in La<sub>1-<i>x</i></sub>Sr<i><sub>x</sub></i>MnO<sub>3 </sub>Thin Films on a-SiO<sub>2</sub> Substrates Produced by Metal Organic Decomposition Method

We have studied magneto-conductive and magnetic properties of La1-xSrxMnO3 (LSMO) thin films on a-SiO2 substrates produced by the metal organic decomposition (MOD) method. LSMO thin films for x = 0, 0.15 and 0.3 have been produced in a pure O2 gas atmosphere. Although LaMnO3 (LMO) single crystal is an antiferromagnetic insulator (AFI), LMO thin films we have produced show ferromagnetic metal (FM) properties for suitable heat treatment conditions. We consider that the excess of O2- ions in LMO thin films produced in a pure O2 gas atmosphere induces the strong hole self-doping into those and the LMO thin films change from AFI to FM. Whereas, the ordinary hole doping is also occurred in LSMO thin films at x > 0. Thus, the carrier doping for LSMO thin films at x > 0 is caused by the hole self-doping by O2- ions and the ordinary hole doping by the replacement of La3+ ions by Sr2+ ones. To investigate the crystallographic and surface structures of the LSMO thin films, X-ray diffraction and SEM measurements have been performed, respectively. From the X-ray diffraction measurement, we have found that all LSMO thin films have perovskite structure and are polycrystalline. From the SEM measurement, we have seen that the LSMO thin films are formed of the aggregation of LSMO fine particles. Electrical resistivities (ERs) and magneto-resistivity (MR) ratios of the LSMO thin films have been measured on the temperature dependence (4K-300K). From MR ratio measurements, the coercive forces of them have been obtained as a function of temperature, and the Curie temperatures have been estimated from the temperature dependences of the coercive forces. We have discussed the origin of the magneto-conductive and magnetic properties of LSMO thin films.

Regulating the valence and size of the active center of Co/Al2O3 catalyst improved the performance and selectivity of NH3-SCO

To improve the activity of Co/Al2O3 catalysts in selective catalytic oxidation of ammonia (NH3-SCO), valence state and size of active centers of Al2O3-supported Co catalysts were adjusted by conducting H2 reduction pretreatment. The NH3-SCO activity of the adjusted 2Co/Al2O3 catalyst was substantially improved, outperforming other catalysts with higher Co-loading. Fresh Co/Al2O3 catalysts exhibited multitemperature reduction processes, enabling the control of the valence state of the Co-active centers by adjusting the reduction temperature. Changes in the state of the Co-active centers also led to differences in redox capacity of the catalysts, resulting in different reaction mechanisms for NH3-SCO. However, in situ diffuse reflectance infrared Fourier transform spectra revealed that an excessive O2 activation capacity caused overoxidation of NH3 to NO and NO2. The NH3-SCO activity of the 2Co/Al2O3 catalyst with low redox capacity was successfully increased while controlling and optimizing the N2 selectivity by modulating the active centers via H2 pretreatment, which is a universal method used for enhancing the redox properties of catalysts. Thus, this method has great potential for application in the design of inexpensive and highly active catalysts.

Fundamentals of NO reduction by liquid wastes: The first application in hazardous waste incineration

To meet increasingly stringent standards of Nitrogen oxide (NOx), it is highly desirable to develop high-efficiency denitration technology during hazardous waste incineration. Therefore, a state-of-art decoupling combustion technology of liquid hazardous wastes (LHW) has been proposed to achieve low NOx emission. In this technology, LHW is introduced into a low-NOx reactor to reduce NOx generated from solid hazardous waste (SHW) incineration prior to its complete combustion. The present article is devoted to clarifying the optimal conditions for denitration reactions by LHW, so the capabilities of nitric oxide (NO) reduction by reduction by LHW model compounds, namely methanol and methylbenzene, were evaluated in fixed-bed and fluidized-bed reactors. The highest denitration efficiency is 78.9% at 900 °C for methanol and 70.0% at 1000 °C for methylbenzene in the test temperature range. The NO reduction activities were closely associated with cracking characteristics of LHW. The presence of oxygen (O2) exhibited different effects on denitration: it promoted NO reduction at low temperatures due to the generation of more denitration-favored agents but suppressed NO reduction at high temperatures due to the oxidation of denitration-favored agents into CO2 and H2O by excessive O2. Moreover, the fluidized-bed reactor, characterized by good heat transfer, exhibited an approximately 17% higher NO reducing efficiency compared to the fixed-bed reactor at low temperatures, but both reactors demonstrated similar NO reduction efficiencies of around 83% at high temperatures. In addition, methanol and methylbenzene showed higher NO reduction efficiencies than their cracking-produced reducing gases, with the reducing gases accounting for approximately 50% of the overall NO reduction efficiency at 1000 °C. According to the above results, a two-step denitration reaction pathway was proposed in which both cracking-formed free radicals and reducing gases contribute to the overall NO reduction. The results of this study can provide valuable insights for NO reduction in the hazardous waste disposal.

Maize catalases are recruited by a virus to modulate viral multiplication and infection.

Given the detrimental effects of excessive reactive oxygen species (ROS) accumulation in plant cells, various antioxidant mechanisms have evolved to maintain cellular redox homeostasis, encompassing both enzymatic components (e.g., catalase, superoxide dismutase) and non-enzymatic ones. Despite extensive research on the role of antioxidant systems in plant physiology and responses to abiotic stresses, the potential exploitation of antioxidant enzymes by plant viruses to facilitate viral infection remains insufficiently addressed. Herein, we demonstrate that maize catalases (ZmCATs) exhibited up-regulated enzymatic activities upon sugarcane mosaic virus (SCMV) infection. ZmCATs played crucial roles in SCMV multiplication and infection by catalysing the decomposition of excess cellular H2 O2 and promoting the accumulation of viral replication-related cylindrical inclusion (CI) protein through interaction. Peroxisome-localized ZmCATs were found to be distributed around SCMV replication vesicles in Nicotiana benthamiana leaves. Additionally, the helper component-protease (HC-Pro) of SCMV interacted with ZmCATs and enhanced catalase activities to promote viral accumulation. This study unveils a significant involvement of maize catalases in modulating SCMV multiplication and infection through interaction with two viral factors, thereby enhancing our understanding regarding viral strategies for manipulating host antioxidant mechanisms towards robust viral accumulation.

Tuning light-driven oxidation of styrene inside water-soluble nanocages

Selective functionalization of innate sp2 C-H bonds under ambient conditions is a grand synthetic challenge in organic chemistry. Here we combine host-guest charge transfer-based photoredox chemistry with supramolecular nano-confinement to achieve selective carbonylation of styrene by tuning the dioxygen concentration. We observe exclusive photocatalytic formation of benzaldehyde under excess O2 (>1 atm) while Markovnikov addition of water produced acetophenone in deoxygenated condition upon photoexcitation of confined styrene molecules inside a water-soluble cationic nanocage. Further by careful tuning of the nanocage size, electronics, and guest preorganization, we demonstrate rate enhancement of benzaldehyde formation and a complete switchover to the anti-Markovnikov product, 2-phenylethan-1-ol, in the absence of O2. Raman spectroscopy, 2D 1H-1H NMR correlation experiments, and transient absorption spectroscopy establish that the site-selective control on the confined photoredox chemistry originates from an optimal preorganization of styrene molecules inside the cavity. We envision that the demonstrated host-guest charge transfer photoredox paradigm in combination with green atom-transfer reagents will enable a broad range of sp2 carbon-site functionalization.

An alfalfa MYB-like transcriptional factor MsMYBH positively regulates alfalfa seedling drought resistance and undergoes MsWAV3-mediated degradation.

Drought is a major threat to alfalfa (Medicago sativa L.) production. The discovery of important alfalfa genes regulating drought response will facilitate breeding for drought-resistant alfalfa cultivars. Here, we report a genome-wide association study of drought resistance in alfalfa. We identified and functionally characterized an MYB-like transcription factor gene (MsMYBH), which increases the drought resistance in alfalfa. Compared with the wild-types, the biomass and forage quality were enhanced in MsMYBH overexpressed plants. Combined RNA-seq, proteomics and chromatin immunoprecipitation analysis showed that MsMYBH can directly bind to the promoters of MsMCP1, MsMCP2, MsPRX1A and MsCARCAB to improve their expression. The outcomes of such interactions include better water balance, high photosynthetic efficiency and scavenge excess H2O2 in response to drought. Furthermore, an E3 ubiquitin ligase (MsWAV3) was found to induce MsMYBH degradation under long-term drought, via the 26S proteasome pathway. Furthermore, variable-number tandem repeats in MsMYBH promoter were characterized among a collection of germplasms, and the variation is associated with promoter activity. Collectively, our findings shed light on the functions of MsMYBH and provide a pivotal gene that could be leveraged for breeding drought-resistant alfalfa. This discovery also offers new insights into the mechanisms of drought resistance in alfalfa.

Potential of Proton-Exchange Membrane Fuel-Cell System with On-Board O2-Enriched Air Generation

Hydrogen fuel-cell systems are one of the alternatives for the decarbonization of the transportation sector. In such systems, the usage of O2-enriched air has the potential to improve fuel cell performance as well as to reduce degradation phenomena linked to local O2 starvation. However, the production of an O2-enriched air stream implies energy consumption that needs to be evaluated in the overall system efficiency. In this study, the potential of a system including polymeric membranes for O2-N2 separation to produce O2-enriched air was evaluated theoretically. First, the balance of plant, including the O2-N2 separation membrane and a two-stage boosting system, was considered. Two sources of energy recovery were identified: a high-pressure H2 stream and retentate flow (N2-rich) at the outlet of the separation membrane. Then, the efficiency of the system was evaluated for different levels of O2 enrichment, with sensitivities to the main operational and design parameters, i.e., cathode excess O2 ratio, turbomachinery efficiency, essure ratios. The results show the potential for an O2-enriched system if the energy recovered reaches approximately 25% of the additional power consumption induced by the separation membrane.

Effect of oxide impurities on the dissolution behavior of Th4+, Be2+ and U4+ in fluoride salts.

Oxides are one of the most important impurities in the fuel salt of molten salt reactors (MSRs), and excessive oxide impurities pose a risk to the safe operation of MSRs. This study focused on investigating the precipitation behavior between Th4+, U4+, and Be2+ with O2- in the 2LiF-BeF2 (FLiBe) eutectic salt system. The results showed that the solubility of UO2 was 5.52 × 10-3 mol kg-1, and the solubility product (Ksp) of UO2 was 6.14 × 10-7 mol3 kg-3 in FLiBe salt at 650 °C. It was also found that the O2- ion would firstly react with U4+ to form UO2, and then the excessive O2- would react with Be2+ to generate BeO in the FLiBe system. Despite conducting the solubility experiment of ThO2 and titration experiment of FLiBe-ThF4, the system failed to achieve the solubility and the Ksp of ThO2. The main reason for this was that O2- preferentially reacted with Be2+ over Th4+ to form precipitates, in other words, Be2+ exerted a protective effect against Th4+. Above all, this work experimentally demonstrated that in the FLiBe system, O2- preferentially combines with U4+ to form a precipitate, followed by Be2+, while Th4+ is relatively inert.

Understanding Oxygen "Buffering" by Caveolae Using Coarse-Grained Molecular Dynamics Simulations.

The "oxygen paradox" embodies the delicate interplay between two opposing biological processes involving oxygen (O2). O2 is indispensable for aerobic metabolism, fuelling oxidative phosphorylation in mitochondria. However, excess O2 can generate reactive species that harm cells. Thus, maintaining O2 balance is paramount, requiring the prioritisation of its benefits while minimising potential harm. Previous research hypothesised that caveolae, specialised cholesterol-rich membrane structures with a curved morphology, regulate cellular O2 levels. Their role in absorbing and controlling O2 release to mitochondria remains unclear. To address this gap, we aim to explore how the structural features of caveolae, particularly membrane curvature, influence local O2 levels. Using coarse-grained (CG) molecular dynamics simulations, we simulate a caveola-like curved membrane and select a CG bead as the O2 model. Comparing a flat bilayer and a liposome of 10 nm diameter, composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), allows us to study changes in the O2 free energy profile. Our findings reveal that curvature has a contrasting effect on the free energy of the outer and inner layers. These findings show the membrane curvature's impact on O2 partitioning in the membrane and O2 permeation barriers, paving the way towards our understanding of the role of caveolae curvature in O2 homeostasis.