• For color stability of beef oxygen must be totally excluded from the packages • The oxygen content decreases stronger at higher initial oxygen content in the packages • The discoloration and oxygen content were measured optically through the packaging • The oxygen sensor spots can be reused due to application to microscope slides • The non-invasive methods allow reproduction of the experiment in slaughterhouses The influence of low oxygen concentrations on the development of color and the myoglobin redox states over storage time was analyzed, to determine whether there are conditions that increase discoloration. Beef slices were packaged in atmospheres containing nitrogen gas and 0%, 0.5%, 1%, 1.5%, 3%, and 5% of oxygen. The samples were stored at 2°C for 14 days. During storage, color, reflectance and oxygen concentration were measured optically through the packaging. The color difference ΔE 2000 and the relative oxymyoglobin (OMb), deoxymyoglobin (DMb), and metmyoglobin (MMb) levels were calculated. After 14 days, the oxygen concentrations changed to 0.09% (0%), 0.36% (0.5%), 0.92% (1%), 1.28% (1.5%) 2.55% (3%), and 4.29% (5%). Regarding MMb formation, the 0% samples (ΔMMb 0-14d 11.1%) were significantly ( p <0.05) more stable compared to the other samples, which showed an increase of MMb formation with rising oxygen concentration after 14 days. The other samples reached a ΔMMb 0-14d increase of 21.1% (0.5%), 26.7% (1%), 30.0% (1.5%), 31.1% (3%), and 34.4% (5%). The color stability showed significantly ( p <0.05) increasing ΔE values of 2.49 (0%), 3.39 (0.5%), 4.66 (1%), 5.14 (1.5%), 6.03 (3%), and 7.34 (5%) with rising oxygen contents. These findings suggest that to ensure the color stability of beef with minimal MMb formation, it is important to completely exclude oxygen from the packages, since the destabilizing effect of oxygen already started at 0.5%. The non-invasive measurement of the oxygen concentration and the reflectance data over 14 days gave new insights into the discoloration process of beef stored in low-oxygen atmospheres.

The escalating world demand for strategic metals like Cu, Co, and Ni calls for efficient and environmentally friendly extraction methods to overcome traditional sulfide ore processing limitations. The conventional pyrometallurgical and acid-based hydrometallurgical routes are hampered by high energy requirements, environmental degradation, and poor metal yields due to passivation layers and undesired gangue reactions, or poor flotation recoveries to produce smeltable concentrates due to magnesium and iron constraints. This research examines alkaline glycine-based leaching as an alternative hydrometallurgical process to recover Cu, Co, and Ni from low-grade polymetallic sulfide ores (2.21% Ni, 0.18% Co, 0.45% Cu, P80 (80 should be a subscript)), which often contain platinum group metals as well. The research aimed to develop an integrated approach to recover these metals from low-grade concentrates. The primary operating parameters, such as glycine-to-Ni molar ratio, pH regulators, dissolved oxygen (DO) concentration, agitation speed, solids ratio, and temperature, were evaluated to determine the extraction of the metals. The results showed that when the glycine/Ni molar ratio was 6:1, double the stoichiometric requirement for the formation of the anionic tris-glycinato Ni (II) and Co(II) complexes, the extraction of Ni and Co was 82.3% and 82%, respectively. In contrast, the extraction of Cu was greater at lower glycine concentrations at the initial leaching stages. Dissolved oxygen (DO) concentration had a major influence on metal recovery, with the maximum extraction being 69.1% Ni, 65.3% Co, and 76.3% Cu at 25 mg/L DO. Optimization of 400 rpm stirring rates enhanced mass transfer and oxygen consumption by 30% from sub-optimal stirring rates. Cu and Co recovery by sodium sulfide precipitation was more than 99.9% Cu, and 98.9% Co. Nickel precipitation was not as effective because, presumably, back-oxidation of nickel sulfides in alkaline conditions occurred. This effect, coupled with the presence of Platinum Group Metals (PGMs), indicates that higher temperature and nitrogen purging would be necessary to improve Ni recovery. The implications of these observations identify the potential for glycine-based leaching to be used as a green, selective, and efficient process to treat refractory sulfide ores with higher recovery of metal content and enhanced sustainability compared to conventional extraction routes. • Alkaline glycine leaching enabled high base metal extraction, achieving 82.3% Ni, 82.0% Co, and 76.3% Cu. • Dissolved oxygen significantly enhanced metal recovery, increasing Ni extraction from 42.6% (no DO) to 69.1% (25 ppm DO). • Glycine leaching accommodated up to 30% solids content, maintaining high extraction efficiencies and reducing processing costs. • Copper recovery via sodium sulfide precipitation exceeded 99.9%, while Co recovery reached 98.9%, demonstrating effective downstream metal recovery.

Innovative model-optimized machine learning for high-accuracy predicting and exploring nitrogen transformation in biomass pyrolysis.

Effects of inoculum sources from different depths and oxygen concentration on bioleaching and microbial community assembly in mine waste dump.

Thermal efficiency optimization of suspension roasting decarbonization for V-bearing shale: Synergistic effects of temperature, gas flow and oxygen concentration on heat utilization

• The effectiveness of a three-layer annular coaxial shroud (TACS) was experimentally validated for laser cladding in open environments. • Oxygen concentration and molten pool protection were ensured when shielding gas flowrate exceeded 30 L/min. • The cross-section profiles of single-track clads were fitted by parabola, sine, and elliptic functions, with the elliptic model showing best accuracy under shielding gas. • The flat-top overlapping model (FOM) was employed to optimize the overlapping coefficient of multi-track clads. • The optimal overlapping coefficient was determined as 0.542, enabling improved surface flatness and reduced pile-up. Cladding active metal for surface repair and complex components fabrication in open environment remains a ground challenge and the advanced laser cladding technique with coaxial shroud protection has exhibited some new promises compared to other traditional deposition methods. In this study, comprehensive and thorough experiments have been carried out, focusing on the protectiveness of a three-layer annular coaxial shroud with qualitative measurements and quantitative data analysis. The experimental results have shown that the Ti6Al4V cladding can be effectively protected when the shielding gas flowrate is greater than 30 L/min. The optimal cross-section profiles of three frequently used models (Parabola, Sine and Elliptic functions) are measured with post-processing. It shows that the parabola model produces the most accurate results without extra shielding gas in terms of R-square values compared with the original cladding profile, whilst the elliptic model is more accurate in describing the cladding profile with extra shielding gas over the same test range. Applying both elliptic function model and flat-top overlapping model, a generalized formulae is then derived to evaluate the horizontal coordinate of the cladding centre point, which is used to determine an optimal overlapping coefficient of 0.542 under an extra shielding gas flowrate of 30 L/min. Further examinations consider four different scenarios, corresponding to four different overlapping ratio ranges. Results are in good agreement with experimental observations. It is worth noting that few literatures have documented to predict the crucial overlapping ratio using the EF model by determining the horizontal coordinate of point C value. Moreover, the elliptic function model proves more precisely representation of experimental data profile while compared to those fitted by Sine Function and Parabola Function models. The observations and findings of this study have shed some lights on current understanding of advanced laser cladding techniques.

Tailoring optical and radiation shielding properties of manganese lead borate glasses via silver iodide modification.

Investigations of ultra-low air stoichiometries in hydrogen fuel cells via operando current and oxygen content cartography and multiphysics simulations

Enhancing copper ion capture in MXene through oxygen content modulation

Transcriptomic analysis of gill tissues in blunt snout bream (Megalobrama amblycephala) under hypoxia and bacterial infection.

In Vitro Evaluation of the Impact of Oxygen Concentrations on Thrombomodulin Expression in a First-Trimester Trophoblast Cell Line.

Surface air-gulping behavior has been reported in several gobiid fishes, but its contribution to oxygen uptake remains unclear. This study aimed to evaluate the air-breathing capacity of Awaous tajasica through behavioral observations, measurement of oxygen consumption, and analysis of the functional morphology of its palate and gills. Behavioral observations demonstrated that under hypoxic conditions, the fish moved to the water surface to engulf air bubbles, which remained within the buccal cavity during aquatic gill ventilation before being expelled through an opercular cavity. Oxygen consumption analysis revealed that A. tajasica obtained approximately 70% of its oxygen from the water and 30% from atmospheric air when under low aquatic oxygen conditions. Palate morphology did not reveal specialized respiratory structures, and only typical sensory structures such as taste buds were observed, indicating the absence of a dedicated aerial exchange surface. The retention of an air bubble in the buccal cavity during low aquatic oxygen concentration supports a functional contribution of air gulping to oxygen uptake in A. tajasica, demonstrating aerial oxygen acquisition without specialized air breathing organs in this gobiid species.

Intracellular oxygen concentration is a pivotal indicator of cellular metabolic and functional states that may be influenced by pathologic conditions, including hypoxia in solid tumors and hyperglycemia. Currently, methods for quantifying cellular oxygen levels-particularly within immune cells implicated in hypoxic dysfunction-are underdeveloped. Here, we introduce a novel biocompatible intracellular oxygen sensor developed by encapsulating the poorly water-soluble phosphorescent dye tris(2-phenylpyridinato)iridium(III) (Ir(ppy)₃) within micelles formed from 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers. This micelle system enables efficient delivery and stable retention of the phosphorescent dye within the cytoplasm. Building on prior confocal microscopy studies characterizing the properties of MPC polymers, our findings reveal that cellular uptake of these polymers occurs via a cell-penetrating translocation mechanism, effectively bypassing significant endosomal sequestration and thus facilitating cytoplasmic oxygen sensing. Micelles prepared with a 30-μM Ir(ppy)₃ stock solution exhibited optimal phosphorescence and clear oxygen sensitivity. Using this sensor, we observed distinct oxygen consumption kinetics between KPL-4 and MDA-MB231 breast cancer cells. Moreover, analysis of the response of NK92-CD16 cells, an NK cell-derived immune cell line, to varying glucose levels revealed that high glucose conditions (300-400mg/dL) significantly suppress the hypoxia-induced increase in phosphorescence, indicating reduced metabolic oxygen demand. Overall, this MPC micelle-encapsulated Ir(ppy)₃ platform serves as a robust tool for evaluating cellular metabolic states and in vitro responses to microenvironmental cues, such as hypoxia and hyperglycemia.

Corrosion of steel in concrete is a key durability issue for reinforced concrete structures, leading to significant economic costs and safety risks. Research suggests that moisture within voids at the steel-concrete interface (SCI) plays a critical role in corrosion. However, experimental evidence clarifying this role remains limited. Here, we systematically investigated the influence of macro-voids at the SCI by exposing reinforced mortar specimens to different wet-dry cycles and to continuous submersion in chloride solution, thereby generating distinct moisture conditions within the interfacial voids. X-ray computed tomography (XCT) was used to monitor the evolution of the gas-liquid configuration inside these voids along with steel corrosion over 9 months. Under wet/dry cycles, corrosion initiated at lower chloride levels than under continuous immersion. XCT revealed that interfacial voids became fully saturated after prolonged immersion but remained partially saturated during wet/dry exposure. These findings are interpreted through the lens of corrosion science and gas-liquid interactions in porous materials. We suggest a mechanism in which the dissolution of pressurized gas bubbles trapped within interfacial voids leads to an increase in dissolved oxygen concentration near the void, thereby locally elevating the steel corrosion potential ( E corr ). Together with chloride accumulation, which gradually lowers the pitting potential, this shift in E corr enhances the likelihood for local corrosion initiation under wet-dry cycles. Overall, this study contributes to understanding how different water exposure conditions affect the local environment at the SCI, providing insight into the mechanistic links between interfacial void gas-liquid content and corrosion in reinforced concrete. • X-ray imaging tracks steel corrosion and moisture evolution in concrete voids. • Cyclic exposure maintains partially saturated voids at the steel-concrete interface. • Wet/dry cycling starts corrosion at lower chloride conc. than continuous immersion. • Interfacial voids promote the formation of conditions favorable for corrosion. • Dissolution of pressurized gas bubbles in voids plays a critical role in corrosion.

Dissolved oxygen concentration control and prediction modelling for liquid LBE loop: UPBEAT loop

ABSTRACT Coalfield fires represent a critical global challenge, causing significant energy loss and posing serious environmental risks. The fracture network within coal seams, as the principal pathway for oxygen migration, plays a pivotal role in governing fire initiation and propagation. This study focuses on the widely distributed asymmetric Y-shaped fracture structures in coal seams and develops a thermo-hydro-chemical multiphysics coupling model that integrates heat transfer, fluid flow, gas diffusion, and oxidation reaction kinetics to simulate the onset and evolution of coal seam fires. Finite element simulations are conducted to systematically examine the influences of fracture intersection angles, matrix diffusion coefficients, and oxygen concentrations on temperature field evolution and heat source migration mechanisms. The results reveal that the migration of temperature extremum points reflects heat source evolution, and the critical time for heat source migration decreases with increasing intersection angle – for instance, from approximately 35 days at 30° to 27 days at 90°. Increasing the matrix diffusion coefficient enhances oxygen penetration depth (from ~5 mm to ~12 mm) and enabling the bifurcation zone to dominate heat accumulation more rapidly, thereby shortening the critical time. Oxygen concentration shows a positive correlation with temperature extremum, reducing oxygen concentration from 21% to 9% delays the critical migration time from approximately 28 days to 51 days, and at 3% concentration, no heat source migration occurs within the simulation period. These findings deepen the understanding of coal fire development mechanisms and provide a quantitative theoretical foundation for precise prediction and targeted prevention of coal seam fires.

Designing luminescent materials with controllable responses to external stimuli is important for optical sensing applications. Here, two heavy-halogen-substituted donor-acceptor emitters based on a dibenzo[a,c]phenazine-3,6-dicarbonitrile scaffold were synthesized and investigated as low-pressure optical sensors under UV excitation (365 nm). In Zeonex films, both compounds exhibit thermally activated delayed fluorescence (TADF), where the emission intensity strongly depends on oxygen concentration, enabling pressure-dependent luminescence. Reduced pressure suppresses oxygen-induced triplet quenching, resulting in enhanced delayed fluorescence. Halogen substitution modulates the photophysical processes and leads to different sensing performances. The brominated derivative shows a maximum pressure sensitivity of 6.8% mbar-1 in the range of 0.1-100 mbar, while the iodinated analogue reaches 1.8% mbar-1 between 1 and 700 mbar. The weak temperature dependence allows reliable pressure readout within the investigated temperature range. These results demonstrate that heavy-halogen substitution provides an effective strategy for developing oxygen-regulated TADF materials for optical pressure sensing.

Single-atom nanozymes (SANs) have recently been recognized as a promising artificial counterpart to natural enzymes. Nevertheless, their catalytic performance remains hindered by insufficient intrinsic activity, which stems from the substantial energy barriers associated with substrate activation and poor mass transport, limiting reactant availability. To address this, we designed a frustrated Lewis pair (FLP)-based Fe-N-C single-atom nanozyme (FLP-Fe-N-C SAzyme) with enriched pyridinic N vacancy defects to enhance oxygen adsorption for the construction of high-performance oxidase mimics. Density functional theory calculations demonstrate that the FLP structure, with Fe as Lewis acid sites and adjacent F regions as Lewis base sites, synergistically promotes oxygen dissociation and induces a pre-adsorbed oxygen atom beside the catalytic center. Such a newly formed structure induced by the FLP sites showed an optimized electronic and geometric structure of the catalytic center, lowering the energy barrier. In addition, the abundant pyridinic-N vacancies induced an enhanced oxygen adsorption, increasing the local oxygen concentration and thereby accelerating reactant availability. Hence, the FLP-Fe-N-C SAzyme remarkably enhances the intrinsic activity of the oxidase-mimicking SANs, achieving a significantly lower Km value than conventional Fe-N-C SANs.

Tunable nanoarchitectonics of porous biochar through sequential calcium and potassium salt activation for high-efficiency removal of emerging pollutants.

Breaking the growth-light trade-off in microalgae: toward efficient phototrophic bioproduction via a physiological-response-guided step-gradient light-downgrading strategy.