Amount Of Oxygen Research Articles

Surface anchoring requirements for vanadia clusters on titanium oxide surfaces and their impact on activity for oxidative dehydrogenation of ethanol

Titanium oxide site requirements for the anchoring of catalytically active forms of dispersed vanadia species are investigated. Using a series of oxygen-modified titanium nitride materials, we systematically modify the available vanadia-anchoring moieties on the titanium-bearing support surface. This strategy in turn results in a very narrow size distribution of well-dispersed vanadia clusters anchored on the support. This synthesis technique ensures that only highly dispersed vanadia is present on the catalyst surface even at nominal monolayer coverages. A deeper insight into the catalytic behavior for ethanol partial oxidation of the active vanadia species is obtained by comparing intrinsic kinetic and thermodynamic parameters of kinetically relevant reaction steps (heat of ethanol adsorption, hydrogen abstraction activation energy, and the energetics of catalyst reoxidation). It is found that these parameters are dependent on the relative amount of oxygen in the titanium-bearing support and the resulting distribution of vanadia species, which validates the premise of a potential participation of lattice oxygen atoms of the titania support into the catalytic activity of active vanadia species.

Oxidative stress, redox status and surfactant metabolism in mechanically ventilated patients receiving different approaches to oxygen therapy (MecROX): An observational study protocol for mechanistic evaluation.

MecROX is a mechanistic sub-study of the UK-ROX trial which was designed to evaluate the clinical and cost-effectiveness of a conservative approach to oxygen therapy for invasively ventilated adults in intensive care. This is based on the scientific rationale that excess oxygen is harmful. Epithelial cell damage with alveolar surfactant deficiency is characteristic of hyperoxic acute lung injury. Additionally, hyperoxaemia (excess blood oxygen levels) may exacerbate whole-body oxidative stress leading to cell death, autophagy, mitochondrial dysfunction, bioenergetic failure and multi-organ failure resulting in poor clinical outcomes. However, there is a lack of in-vivo human models evaluating the mechanisms that underpin oxygen-induced organ damage in mechanically ventilated patients. The aim of the MecROX mechanistic sub-study is to assess lung surfactant composition and global systemic redox status to provide a mechanistic and complementary scientific rationale to the UK-ROX trial findings. The objectives are to quantify in-vivo surfactant composition, synthesis, and metabolism with markers of oxidative stress and systemic redox disequilibrium (as evidenced by alterations in the 'reactive species interactome') to differentiate between groups of conservative and usual oxygen targets. After randomisation into the UK-ROX trial, 100 adult participants (50 in the conservative and 50 in usual care group) will be recruited at two trial sites. Blood and endotracheal samples will be taken at 0, 48 and 72 hours following an infusion of 3 mg/kg methyl-D 9-choline chloride. This is a non-radioactive, stable isotope of choline (vitamin), which has been extensively used to study surfactant phospholipid kinetics in humans. This study will mechanistically evaluate the in-vivo surfactant synthesis and breakdown (by hydrolysis and oxidation), oxidative stress and redox disequilibrium from sequential plasma and bronchial samples using an array of analytical platforms. We will compare conservative and usual oxygenation groups according to the amount of oxygen administered. Trial registration: ISRCTNISRCTN61929838, 27/03/2023 https://doi.org/10.1186/ISRCTN61929838.

The effect of RF sputtering power on structural, nanomechanical and tribological properties of single layered TaN coatings

Single-layered TaN thin coatings were deposited on Ti6Al7Nb alloy substrates using reactive radiofrequency magnetron sputtering, with variations in target power. To assess the crystalline structure, chemical composition, and surface topography of these coatings, Grazing Incidence x-ray Diffraction (GIXRD), Energy Dispersive Spectroscopy (EDS), and Scanning Probe Microscopy (SPM) were employed, respectively. The study revealed that deposition power impacts the structure and composition of TaN coatings. Further analysis using x-ray Photoelectron Spectroscopy (XPS) indicated that the TaN coatings predominantly consisted of Ta and N, with trace amounts of oxygen (O 1s). Additionally, nanomechanical testing was conducted to evaluate hardness (H), modulus (E), and scratch properties. Results suggested that multiphase hex-TaN coatings exhibited superior H, E, and scratch properties compared to other cubic-structured TaN coatings. Friction and wear properties against steel balls under dry sliding conditions were determined using a ball-on-disk nanotribometer. The findings showed that mix-phase TaN coating exhibited a minimum coefficient of friction of 0.054 and a wear rate of 2.14 × 10−6 mm3/N.m. Abrasion, ploughing and oxidation were identified as the primary wear mechanism responsible for the wear of the TaN coatings.

Assessing the Effect of Aluminium Oxide Nanoparticle Additives on Biodiesel Combustion in Marine Diesel Engines

Abstract The increases in annual ship exhaust emissions have prompted the shift towards adopting alternative energy sources. Biodiesel is a suitable substitute fuel for marine engines that does not necessitate engine alterations. Biodiesel is renewable, environmentally friendly, and plant-based with biodegradable properties. The fuel is also non-toxic and oxygenated and shares similar characteristics with diesel fuel. Nonetheless, biodiesel fuel exhibits slightly reduced performance compared to diesel primarily due to its lower energy content. This study aims to evaluate the combustion attributes of a marine diesel engine employing palm biodiesel fuel incorporated with aluminium oxide (Al2O3) nanoparticle additives. A B20 biodiesel fuel was blended with 50, 100, and 150 ppm Al2O3 nano additives. The engine combustion parameters, in-cylinder pressure, heat release rate (HRR), mass fraction burned, and ignition delay were analysed and compared to the B20 fuel without additives. Adding Al2O3 nano additives to the B20 biodiesel blend improved the engine combustion characteristics. The optimal performance was recorded by the blend incorporating 150 ppm nanoparticles. The in-cylinder pressure and HRR peaks also improved by 5.41 to 15.1% and 4.69 to 16.9%, respectively, compared to the other B20 fuel blends. Furthermore, the B20 mixed with Al2O3 documented a more rapid mass fraction burned rate, resulting in a shorter ignition delay of approximately 5 CA°. In addition, the amount of oxygen in biodiesel blended with Al2O3 nano additives has improved engine combustion compared to B20 fuel. The present study demonstrated that adding Al2O3 nano additives to palm biodiesel fuel significantly enhanced engine combustion attributes, thus highlighting its potential to reduce reliance on petroleum-based fuels and provide sustainable fuel alternatives for marine diesel engines.

Study of the Structure of Zn and Na Borophosphate Glasses Using X-ray and Neutron Scattering Techniques

The atomic structures of Zn and Na borophosphate glasses were studied using X-ray and neutron scattering techniques. Peaks assigned to the B−O, P−O, and O−O distances confirm that only BO4 units co-exist with the PO4 tetrahedra. The Zn−O and Na−O coordination numbers are found to be a little larger than four. The narrowest peaks of the Zn−O first-neighbor distances exist for the glasses along a line connecting the Zn(PO3)2 and BPO4 compositions (50 mol% P2O5), which is explained by networks of ZnO4, BO4, and PO4 tetrahedra with twofold coordinated oxygens. The calculated amounts of available oxygen support this interpretation. Broadened peaks occur for glasses with lower P2O5 contents, which is consistent with the presence of threefold coordinated oxygens. The two distinct P−O peak components of the Zn and Na borophosphate glasses differ in their relative abundances. This is interpreted as follows: Na+ cations coordinate oxygens in some P−O−B bridges, which is something not seen for the Zn2+ ions.

Combined Effects of Anti-PD-L1 and Nanosonodynamic Therapy on HCC Immune Activation in Mice: An Investigation.

Current therapeutic strategies, including immune checkpoint blockade (ICB), exhibit limited efficacy in treating hepatocellular carcinoma (HCC). Nanoparticles, particularly those that can accumulate specifically within tumors and be activated by sonodynamic therapy (SDT), can induce immunogenic cell death (ICD); however, ICD alone has not achieved satisfactory therapeutic effectiveness. This study investigates whether combining ICB with ICD induced by nanoparticle-mediated SDT could enhance anti-tumor immunity and inhibit HCC growth. We developed an iron-based micelle nanodelivery system encapsulating the Near-Infrared Dye IR-780, which was surface-modified with a cyclic tripeptide composed of arginine-glycine-aspartic acid (cRGD). This led to the synthesis of targeted IR780@FOM-cRGD nanoparticles. These nanoparticles were specifically engineered to kill tumor cells under sonication, activate immunogenic cell death (ICD), and be used in conjunction with immune checkpoint blockade (ICB) for the treatment of hepatocellular carcinoma (HCC). The synthesized IR780@FOM-cRGD nanoparticles had an average diameter of 28.23±1.750 nm and a Zeta potential of -23.95±1.926. Confocal microscopy demonstrated that IR780@FOM-cRGD could target HCC cells while minimizing toxicity to healthy cells. Upon sonodynamic activation, these nanoparticles consumed significant amounts of oxygen and generated substantial reactive oxygen species (ROS), effectively killing tumor cells and inhibiting the proliferation, invasion, and migration of H22 cells. Hemolysis assays confirmed the in vivo safety of the nanoparticles, and in vivo fluorescence imaging revealed significant accumulation in tumor tissues. Mouse model experiments showed that combining ICB(which induced by Anti-PD-L1) with ICD (which induced by IR780@FOM-cRGD), could effectively activated anti-tumor immunity and suppressed tumor growth. This study highlights the potential of IR780@FOM-cRGD nanoparticles to facilitate tumor eradication and immune activation when used in conjunction with Anti-PD-L1 therapy. This combination represents a non-invasive, efficient, and targeted approach for the treatment of hepatocellular carcinoma (HCC). By integrating sonodynamic therapy with immunotherapy, this strategy promises to substantially improve the effectiveness of traditional treatments in combating HCC, offering new avenues for clinical application and therapeutic innovation.

Formulation of N-doped carbon with meso/microporous structure for supercapacitors through biotemplates

Developing carbon materials based on biomass for supercapacitors has enormous potential to address the pressing issues of resource waste and environmental contamination. Nevertheless, biomass-based supercapacitors confront two major challenges: limited pore structure and the absence of surface functional groups. In this research, urea (U) acted as the nitrogen dopant, eggshells (ES) as the biotemplate, and eucalyptus leaves (EL) as the primary raw material to produce N-doped hierarchical porous carbon via co-pyrolysis. The results demonstrated that ES0.25U1 possesses a large specific surface area (SSA) of 1742.59 m2.g−1 and an excellent meso/microporous structure. Furthermore, significant quantities of oxygen (25.22 %) and nitrogen (3.18 %) were detected in ES0.25U1. The ES0.25U1 exhibits a specific capacitance (Cs) of 349F.g−1 (0.5 A.g−1), and the symmetric supercapacitor constructed from it possesses an energy density of 7.57 Wh.kg−1 while maintaining a capacity retention rate of 92.57 % and a Coulombic efficiency of 98.76 % after 10,000 charging/discharging cycles. Moreover, a comprehensive exploration into the N-doping mechanism and the underlying principles governing the formation of meso/microporous architectures through the utilization of bio-templates has been undertaken. This work provides a robust theoretical framework for the rational design and fabrication of high-value bio-derived carbonaceous materials utilizing combinatorial strategies of biotemplates and heteroatom doping.

DOCOL 1100M WELDING IN THE CONSTRUCTION OF ELECTRIC MEANS OF TRANSPORT

Advanced high-strength steels are important for the automotive sector. Metal active gas (MAG) is the most popular method for joining grades of steel. The goal of the paper is to analyze the mechanical properties of the MAG welding joint made of high-strength DOCOL 1100M intended for the construction of electric vehicles. The manuscript shows a basic understanding of the properties of DOCOL joints. This type of material is characterized by a martensitic microstructure, which makes it difficult to make a proper joint. The tensile strength, metallographic structure, and type of non-metallic inclusions were analyzed as a function of the oxygen amount in the protective gas mixture. Investigations of oxide non-metallic inclusions were carried out using scanning electron microscopy. This article attempts to obtain high joint strength of the electric vehicle structure by controlling the average size of non-metallic inclusions in the weld, which is influenced by shielding gas in the MAG welding process. The solution has application potential for the automotive industry, especially for electric vehicles.

CORRELATION OF ISOCAPNIC BUFFERING PHASE WITH AEROBIC AND ANAEROBIC POWER IN ATHLETES

Objective: The aim of the study below was to detect the relationship of isocapnic buffering phase values with the values of both aerobic and anaerobic power. Method: A total of 14 athletes, five females and nine males with ages between 18 and 25, who all have been active in sports for at least five years, volunteered to participate in the present study. At the beginning, the values of height, body mass, and body fat ratio of the volunteers were collected as required. Then, a maximal exercise test was applied to the volunteers and during the test, the values of maximal oxygen consumption capacity (VO2max), amount of oxygen consumed (VO2), amount of carbon dioxide produced (VCO2), respiratory threshold, respiratory compensation point, and maximal heart rate were determined accordingly. One week after aforesaid measurements, the Wingate anaerobic test was applied to the volunteers and the anaerobic power values were calculated. Initially, the descriptive statistics of the data obtained in the study were accomplished. Since the data did not reflect a normal distribution, the Spearman correlation analysis was applied to detect the correlation between both the aerobic and anaerobic power data and the isocapnic buffering data. The level of significance was accepted as p < 0.05. Results: Whereas a positive correlation was observed between VO2max (ml/kg/min) values and the values of maximum power (W/kg), average power (W/kg) and, minimum power (W/kg), a negative correlation was observed between VO2max (ml/kg/min) and power drop values (%) in female volunteers. For male volunteers, on the other hand, a positive correlation was observed between the values of VO2max (ml/kg/min) and minimum power (W/kg), and a negative correlation between the values of VO2max (ml/kg/min) and power drop (%). Furthermore, a significant relationship was also found between the values of isocapnic buffering and hypocapnic hyperventilation, and the values of maximal heart rate (beats/min), respiratory threshold VO2 (ml/kg/min), respiratory threshold heart rate (beats/min), respiratory threshold speed (km/hour), respiratory compensation point heart rate (beats/min), and respiratory compensation point speed (km/hour) in both male and female volunteers. Conclusion: The findings collected hereby indicate that as the VO2max levels of athletes increase, both their cardiopulmonary data and anaerobic power values and also their ability to resist against the intensity of exercises applied after entering the anaerobic threshold, increase. Meanwhile, the rises in VO2max levels of athletes suggest that it will contribute to an athlete’s better performance by causing decreases in the power drop ratios (%) attained during the Wingate test.

Determination of the amount of oxygen required for each function in the bacterial cell during phenol biodegradation in wastewater: a unique concept

The goal of this study is to provide more in-depth study into the biodegradation of phenol and to determine the amount of oxygen required for each function in the bacterial cell which is fundamental in understanding of cell metabolism and biology. The total amount of oxygen consumed by bacteria is determined using manometric technique. In the biodegradation of phenol (less than 150 mg/L) the oxygen consumed up to the plateau (the stage associated with the termination of carbon) is found to be composed of three portions, one is used to directly oxidize portion of the substrate to produce energy to allow normal cell functions to sustain life which is estimated to be 50% of the plateau BOD (biochemical oxygen demand), the second portion is to oxidize energy storage intermediate (most probably carbon mono oxide, CO, is oxidized to CO2) to release energy which is then used to power reproduction which is estimated to be 41.75% of the plateau BOD, third portion is incorporated into the produced new cells which is estimated to be 8.25% of the plateau BOD. The correlation coefficient between the initial phenol concentration and the ultimate BOD values is found to be r = 0.9999. This value of correlation coefficient, r, may indicate that microbes are, in a way, estimating the amount of food available and they grow and reproduce accordingly. This article provides a better understanding of cell metabolism and biology. This understanding of cell metabolism may offer better understanding of human cells. The results of this research paves the way for a similar research on human cells where abnormal oxygen uptake may assist in early prediction of cells dysfunction and diseases and may help in early taking the necessary precautions to avoid illness.

Doping control analysis of myo-inositol trispyrophosphate and 10 bisphosphonates in equine plasma by ion chromatography-mass spectrometry and its application to clodronic acid horse administration.

Bisphosphonates and myo-inositol trispyrophosphate (ITPP) are two classes of difficult-to-detect polar drugs that are prohibited under the rules of racing. ITPP is a drug capable of increasing the amount of oxygen in hypoxic tissues, and studies have shown that administration of ITPP increases the maximal exercise capacity in mice. The properties of ITPP make it an ideal candidate as a doping agent to enhance performance in racehorses. In recent years, ITPP had indeed been detected in racehorses and confiscated items. As for bisphosphonates, it is especially critical to control their use as since February 2019, the International Agreement on Breeding, Racing and Wagering (IABRW) by the International Federation of Horseracing Authorities (IFHA) had identified specific conditions on which bisphosphonates should not be administered to a racehorse. A recent review of literature shows that there is yet a simultaneous screening method for detecting ITPP and bisphosphonates in equine samples. This paper describes an efficient ion chromatography high-resolution mass spectrometry (IC-HRMS) method for the simultaneous detection of ITPP and 10 bisphosphonates at sub-parts-per-billion (ppb) to low-ppb levels in equine plasma after solid-phase extraction (SPE) and its application to an administration study of clodronic acid in horses.

Impact of B-site cations of MgX2O4 (X=Cr, Fe, Mn) spinels on the chemical looping oxidative dehydrogenation of ethane to ethylene

Chemical looping oxidative dehydrogenation (CL-ODH) provides a multifunctional conversion platform that can take advantage of the selective oxidation of lattice oxygen in oxygen carrier to achieve high-valued ethane to ethylene conversion. In this study, we explored the effect of B-site element in MgX2O4 (X=Cr, Fe, or Mn) spinel-type oxygen carriers on the performance of ethane CL-ODH. The properties test and characterization of MgX2O4 spinel were tested by fixed bed and H2-TPR, O2-TPD, TG, in-situ Raman, SEM, and TEM. The results showed that because MgCr2O4 only released a small amount of adsorbed surface oxygen, it tended to catalyze the conversion of ethane to coke and hydrogen. MgFe2O4 facilitated the deep oxidation of ethane into CO2 by providing more surface lattice oxygen. Meanwhile, since a significant amount of bulk lattice oxygen was released by the MgMn2O4 oxygen carrier, it could burn hydrogen in a targeted manner to advance the reaction and increased ethylene’s selectivity. Thereby, MgMn2O4 achieved an ethane conversion of 73.72% with an ethylene selectivity of 81.46%. Furthermore, the MgMn2O4 catalyst demonstrated stable reactivity and an ethylene yield of about 62.00% in ethane CL-ODH over the 30 redox cycles. The screening tests indicated that the B-site elements in MgX2O4 spinel oxides could significantly influence their ability to supply lattice oxygen, thereby affecting their performance in ethane CL-ODH reaction.

An Automatized Rebalancing System to Address Faradaic Imbalance and Prolong Cycle Life in Alkaline Ferrocyanide – Anthraquinone Redox Flow Batteries

AbstractAqueous Organic Redox Flow Batteries are a family of promising energy storage systems. However, they face various challenges related to their lifetime, such as the Faradaic imbalance due to the occurrence of parasitic reaction leading to the fading of its energy storage capacity. Herein, automatization of a rebalancing system to reverse the detrimental effects of Faradaic imbalance due to the unavoidable presence of small quantities of oxygen in the negative reservoir or hydrogen evolution reaction is developed and implemented in an alkaline flow battery. A membrane‐free rebalancing cell is proposed to promote the oxygen evolution reaction and reverse the accumulated charge in the catholyte showing a 100 % coulombic efficiency. The programmable logic controller monitors the open circuit voltage to calculate the charge stored in each charge/discharge step and closes a circuit so a fixed voltage is applied to the rebalancing cell when the battery needs to be rebalanced. The system is tested using an alkaline flow battery consisting of ferrocyanide and 2,6‐dihydroxyanthraquinone, improving the energy capacity retention from 0.27 % cycle‐1 and 0.47 % h‐1 without rebalancing system to 100 % retention after >850 cycles and >24 days (without Ar‐filled glovebox), demonstrating the feasibility of this proposed system to address the Faradaic imbalance.

Thermodynamic characteristics and mechanism of low-rank coal oxidation in oxygen-poor environment

Aiming at the restricted oxygen environment of coal mine, this paper focus on the whole process from physical adsorption to chemical reaction between coal and oxygen, and quantum chemical calculations investigate the potentiating or inhibiting effects of different active groups on the amount of oxygen adsorbed and thermally released from the main coal structure, and experimentally investigate the effect of oxygen concentration (OC) on the transformation relationship between active functional groups and active sites. The results showed the coal side-chain structure has an effect on the heat release characteristics of the aromatic ring in the process of oxygen adsorption, and the heat of adsorption of the aromatic ring with alkyl and aldehyde side-chains reaches 422.706 kJ/mol. The relationship between carbon oxide release and temperature at different OC all conformed to the exponential function model, and the apparent activation energy was positively correlated with the OC. The increase of OC narrows the gap between the production and consumption rates of active sites, which is helpful for the further understanding of the coal spontaneous combustion (CSC).

Enhanced mobility of iron and manganese on Mars: Evidence from kinetic experiments and models

Several missions have reported complex alteration mineralogies on early Mars, which preserve environmental records of multiple water-rock-atmosphere interactions. The MSL and M2020 missions in Gale and Jezero have identified Fe and Mn-bearing secondary phases. These elements are used as tracers for the redox conditions on both Earth and Mars. However, to fully understand the short-lived and local-scale processes observed on Mars, it is necessary to go beyond thermodynamic models and experiments. Enhancing our ability to interpret the redox and hydrological conditions from the observed phase assemblage requires understanding the evolution of Fe and Mn during weathering. This study reports the results of kinetic alteration experiments and geochemical models conducted under Mars-like conditions. We tested variable pO2, pCO2, temperatures, and starting solutions. The results suggest that Fe is more mobile on Mars than on Earth, with a pseudo-equilibrium concentration that is kinetically controlled by dissolution and oxidation rates. Despite some initially modeled siderite precipitation, no siderite precipitation was observed in the altered powder. Solutions with higher acid concentrations were primarily controlled by dissolution kinetics, with both Fe and Mn being mobile, even when a minor amount of P, Fe, and S bearing secondary phases are formed. Based on our experimental results, we updated the model and conducted two large-scale sensitivity tests on our kinetic simulation. We confirmed that our experiments were too high in pO2 for siderite to form; however, we found that over a range of clearly oxidizing conditions from an equilibrium standpoint, Fe and Mn are mostly mobile, and siderite precipitation can occur. We were able to determine the pO2, pCO2 and the temporal space where Fe-oxide or siderite predominate or coexist, constraining the meaning of reducing or oxidizing conditions. Moreover, we also observed that siderite formation would require a much longer water residence time than Fe-oxide to precipitate, interpreted as higher weathering rates, or later evaporation required to effectively precipitate under any conditions. On ancient Mars, both Fe and Mn would be relatively mobile and prone to be leached from their host rock. Observing siderite or oxide would not primarily be a redox marker but would be a clue to a different hydrological regime. At the planetary scale, it would be challenging to form authigenic siderite during alteration. Although siderite would not indicate the presence of a particularly reducing atmosphere and that Mn-oxides are mainly pH controlled and do not require terrestrial-level amounts of oxygen, a collocated precipitation of siderite and Mn-oxides could also provide valuable information to constrain the redox environment of the ancient Mars.

Non-invasive determination of critical dissolved oxygen thresholds for stress physiology in fish using triple-oxygen stable isotopes and aquatic respirometry

ABSTRACT Understanding the critical thresholds of dissolved oxygen (O2) that trigger adaptive physiological responses in aquatic organisms is long hampered by a lack of robust, non-lethal or non-invasive methodologies. The isotope fractionation of triple O2 isotopes (18O/17O/16O) during respiration is linked to the amount of oxygen utilised, offering a potential avenue for new insights. Our experimental research involved measuring the oxygen isotope fractionation of dissolved O2 in closed-system aquatic respirometry experiments with wild sticklebacks (Gasterosteus aculeatus). These fish were either naturally adapted or experimentally acclimated to hypoxic and normoxic conditions. The aim was to observe their oxygen usage and isotope fractionation in response to increasingly severe hypoxia. Initial observations revealed a progressive 18O enrichment from the preferential uptake of 16O to a dissolved oxygen threshold of 3–5 mg O2 L–1, followed by an apparent reversal in oxygen isotope fractionation, which is mixing of 16O and 17O with the remaining O2 pool across all populations and indicative of a systematic change in oxygen metabolism among the fish. Unexpectedly, sticklebacks adapted to hypoxia but acclimated to normoxia exhibited stronger oxygen isotope fractionation compared to those adapted to normoxia and acclimated to hypoxia, contradicting the hypothesis that hypoxia adaptation would lead to reduced isotope discrimination due to more efficient oxygen uptake. These preliminary experimental results highlight the novel potential of using dissolved O2 isotopes as a non-invasive, non-lethal method to quantitatively assess metabolic thresholds in aquatic organisms. This approach could significantly improve our understanding of the critical oxygen responses and adaptation mechanisms in fish and other aquatic organisms across different oxygen environments, marking a significant step forward in aquatic ecological and physiological research.

Mechanical Properties of Ti Grade 2 Manufactured Using Laser Beam Powder Bed Fusion (PBF-LB) with Checkerboard Laser Scanning and In Situ Oxygen Strengthening

Additive manufacturing (AM) technologies have advanced from rapid prototyping to becoming viable manufacturing solutions, offering users both design flexibility and mechanical properties that meet ISO/ASTM standards. Powder bed fusion using a laser beam (PBF-LB), a popular additive manufacturing process (aka 3D printing), is used for the cost-effective production of high-quality products for the medical, aviation, and automotive industries. Despite the growing variety of metallic powder materials available for the PBF-LB process, there is still a need for new materials and procedures to optimize the processing parameters before implementing them into the production stage. In this study, we explored the use of a checkerboard scanning strategy to create samples of various sizes (ranging from 130 mm3 to 8000 mm3 using parameters developed for a small 125 mm3 piece). During the PBF-LB process, all samples were fabricated using Ti grade 2 and were in situ alloyed with a precisely controlled amount of oxygen (0.1–0.4% vol.) to enhance their mechanical properties using a solid solution strengthening mechanism. The samples were fabricated in three sets: I. Different sizes and orientations, II. Different scanning strategies, and III. Rods for high-cycle fatigue (HCF). For the tensile tests, micro samples were cut using WEDM, while for the HCF tests, samples were machined to eliminate the influence of surface roughness on their mechanical performance. The amount of oxygen in the fabricated samples was at least 50% higher than in raw Ti grade 2 powder. The O2-enriched Ti produced in the PBF-LB process exhibited a tensile strength ranging from 399 ± 25 MPa to 752 ± 14 MPa, with outcomes varying based on the size of the object and the laser scanning strategy employed. The fatigue strength of PBF-LB fabricated Ti was 386 MPa, whereas the reference Ti grade 2 rod samples exhibited a fatigue strength of 312 MPa. Our study revealed that PBF-LB parameters optimized for small samples could be adapted to fabricate larger samples using checkerboard (“island”) scanning strategies. However, some additional process parameter changes are needed to reduce porosity.

Thermodynamic Model for Hydrogen Production from Rice Straw Supercritical Water Gasification.

Supercritical water gasification (SCWG) technology is highly promising for its ability to cleanly and efficiently convert biomass to hydrogen. This paper developed a model for the gasification of rice straw in supercritical water (SCW) to predict the direction and limit of the reaction based on the Gibbs free energy minimization principle. The equilibrium distribution of rice straw gasification products was analyzed under a wide range of parameters including temperatures of 400-1200 °C, pressures of 20-50 MPa, and rice straw concentrations of 5-40 wt%. Coke may not be produced due to the excellent properties of supercritical water under thermodynamic constraints. Higher temperatures, lower pressures, and biomass concentrations facilitated the movement of the chemical equilibrium towards hydrogen production. The hydrogen yield was 47.17 mol/kg at a temperature of 650 °C, a pressure of 25 MPa, and a rice straw concentration of 5 wt%. Meanwhile, there is an absorptive process in the rice straw SCWG process for high-calorific value hydrogen production. Energy self-sufficiency of the SCWG process can be maintained by adding small amounts of oxygen (ER < 0.2). This work would be of great value in guiding rice straw SCWG experiments.

Modulation of Photosystem II Function in Celery via Foliar-Applied Salicylic Acid during Gradual Water Deficit Stress.

Water deficit is the major stress factor magnified by climate change that causes the most reductions in plant productivity. Knowledge of photosystem II (PSII) response mechanisms underlying crop vulnerability to drought is critical to better understanding the consequences of climate change on crop plants. Salicylic acid (SA) application under drought stress may stimulate PSII function, although the exact mechanism remains essentially unclear. To reveal the PSII response mechanism of celery plants sprayed with water (WA) or SA, we employed chlorophyll fluorescence imaging analysis at 48 h, 96 h, and 192 h after watering. The results showed that up to 96 h after watering, the stroma lamellae of SA-sprayed leaves appeared dilated, and the efficiency of PSII declined, compared to WA-sprayed plants, which displayed a better PSII function. However, 192 h after watering, the stroma lamellae of SA-sprayed leaves was restored, while SA boosted chlorophyll synthesis, and by ameliorating the osmotic potential of celery plants, it resulted in higher relative leaf water content compared to WA-sprayed plants. SA, by acting as an antioxidant under drought stress, suppressed phototoxicity, thereby offering PSII photoprotection, together with enhanced effective quantum yield of PSII photochemistry (ΦPSII) and decreased quantity of singlet oxygen (1O2) generation compared to WA-sprayed plants. The PSII photoprotection mechanism induced by SA under drought stress was triggered by non-photochemical quenching (NPQ), which is a strategy to protect the chloroplast from photo-oxidative damage by dissipating the excess light energy as heat. This photoprotective mechanism, triggered by NPQ under drought stress, was adequate in keeping, especially in high-light conditions, an equal fraction of open PSII reaction centers (qp) as of non-stress conditions. Thus, under water deficit stress, SA activates a regulatory network of stress and light energy partitioning signaling that can mitigate, to an extent, the water deficit stress on PSII functioning.

Anticandidal effect of multiple sessions of erythrosine and potassium iodide-mediated photodynamic therapy

ABSTRACT Background Erythrosine+potassium iodide-mediated photodynamic therapy has shown an anticandidal effect. Single session, however, has inadequate fungal inhibition. Objectives We aimed to examine the effects of multiple aPDT sessions on Candida albicans inhibition and singlet oxygen formation. Methods 220 μM erythrosine +/-100 mM potassium iodide was applied to C. albicans biofilms for 1 min prior to irradiation at 530±10 nm using a 250 mW/cm2 light-emitting diode. Negative and positive controls were phosphate buffer saline and nystatin, respectively. Single, double and triple irradiation sessions with a 5 min resting time between sessions were performed. Post-treatment candidal counts were done at 0, 1 6 and 24 hr while log10 colony forming unit/ml was calculated and compared using a Kruskal-Wallis with Dunn’s post hoc test at a p<0.05 - Singlet oxygen amount was compared using one-way ANOVA with a post hoc test at a p< 0.05. Results Two and three irradiation sessions to erythrosine+potassium iodide could inhibit Candida albicans at 7.92 log10CFU/ml (p < 0.001) . Singlet oxygen from a combination groups was significantly higher than for erythrosine (positive control). Moreover, the correlation coefficient (r) between singlet oxygen production and decreased Candida albicans counts was equal to 1. Conclusion Multiple sessions PDT of 220 μM erythrosine+100 mM potassium iodide effectively inhibited a Candida biofilm.