Low Oxygen Concentrations Research Articles

Hypoxia related genes modulate in similar fashion in skin fibroblast cells of yak (Bos grunniens) adapted to high altitude and native cows (Bos indicus) adapted to tropical climate during hypoxia stress.

The present study was conducted to understand transcriptional response of skin fibroblast of yak (Bos grunniens) and cows of Bos indicus origin to hypoxia stress. Six primary fibroblast cell lines derived from three individuals each of Ladakhi yak (Bos grunniens) and Sahiwal cows (Bos indicus) were exposed to low oxygen concentration for a period of 24h, 48h and 72h. The expression of 10 important genes known to regulate hypoxia response such as HIF1A, VEGFA, EPAS1, ATP1A1, GLUT1, HMOX1, ECE1, TNF-A, GPx and SOD were evaluated in fibroblast cells of Ladakhi yak (LAY-Fb) and Sahiwal cows (SAC-Fb) during pre- and post-hypoxia stress. A panel of 10 reference genes (GAPDH, RPL4, EEF1A1, RPS9, HPRT1, UXT, RPS23, B2M, RPS15, ACTB) were also evaluated for their expression stability to perform accurate normalization. The expression of HIF1A was significantly (p < 0.05) induced in both LAY-Fb (2.29-fold) and SAC-Fb (2.07-fold) after 24h of hypoxia stress. The angiogenic (VEGFA), metabolic (GLUT1) and antioxidant genes (SOD and GPx) were also induced after 24h of hypoxia stress. However, EPAS1 and ATP1A1 induced significantly (p < 0.05) after 48h whereas, ECE1 expression induced significantly (p < 0.05) at 72h after exposure to hypoxia. The TNF-alpha which is a pro-inflammatory gene induced significantly (p < 0.05) at 24h in SAC-Fb and at 72h in LAY-Fb. The induction of hypoxia associated genes indicated the utility of skin derived fibroblast as cellular model to evaluate transcriptome signatures post hypoxia stress in populations adapted to diverse altitudes.

Effects of novel carbon sources additives on the solid-state sintering behavior and properties of SiC ceramics

To enhance the density of SiC and improve the purity of the SiC, carbon is frequently used as a sintering additive. SiC ceramics were prepared in this study by using various carbon sources (graphitic carbon microsphere, carbon black, and flake graphite) combined with B4C through spark plasma sintering (SPS) at temperatures ranging from 1800 °C to 1900 °C. Among the above carbon sources, the graphitic carbon microspheres were created by hydrothermal carbonization combined with catalytic graphitization. The influence of the carbon sources on the phase compositions, microstructure, physical properties, and oxidation resistance of the SiC specimens was investigated. The findings revealed that the SiC specimens prepared with graphitic carbon microsphere had a smaller crystallite size than those prepared with other kinds of carbon. The SiC specimens prepared with graphitic carbon microsphere displayed high relative density, hardness, fracture toughness, and remarkable oxidation resistance. This was attributed to the lower oxygen content, better dispersion, and higher chemical reactivity of graphitic carbon spheres. In terms of the oxidation resistance of SiC specimens, factors such as purity (residual carbon) and porosity were found to have a more significant impact than grain size. In general, the use of carbon sources with high reactivity and good dispersion is an effective method in preparing SiC ceramics.

Manipulation of Oxidation States on Phase Boundary via Surface Layer Modification for Enhanced Alkaline Hydrogen Electrocatalysis.

In alkaline water electrolysis and anion exchange membrane water electrolysis technologies, the hydrogen evolution reaction (HER) at the cathode is significantly constrained by a high energy barrier during the water dissociation step. This study employs a phase engineering strategy to construct heterostructures composed of crystalline Ni4W and amorphous WOx aiming to enhance catalytic performance in the HER under alkaline conditions. This work systematically modulates the oxidation states of W within the amorphous WOx of the heterostructure to adjust the electronic states of the phase boundary, the energy barriers associated with the water dissociation step, and the adsorption/desorption properties of intermediates during the alkaline HER process. The optimized catalyst, Ni4W/WOx-2, with a quasi-metallic state of W coordinated by a low oxygen content in amorphous WOx, demonstrates exceptional catalytic performance (22 mV@10mA cm-2), outperforming commercial Pt/C (30 mV@10mA cm-2). Furthermore, the operando X-ray absorption spectroscopy analysis and theoretical calculations reveal that the optimized W atoms in amorphous WOx serve as active sites for water dissociation and the nearby Ni atoms in crystalline Ni4W facilitated the release of H2. These findings provide valuable insights into designing efficient heterostructured materials for energy conversion.

Detection, movement and persistence of invertebrate eDNA in groundwater

Sampling groundwater biodiversity is difficult because of limited access and issues with species identification. Environmental DNA (eDNA) provides a viable alternative to traditional sampling approaches, however limited knowledge of the abundance and fate of DNA in groundwater hinders the interpretation of data from these environments. Groundwater environments are dark and have lower oxygen concentrations and microbial activity than surface waters. Consequently, assumptions about DNA fate in surface ecosystems may not apply to groundwaters. Here, we test the longevity and transport of eDNA in groundwater within a static microcosm and a flow-through mesocosm. A variety of invertebrates were placed within a mesocosm and microcosm to enable DNA shedding, and then removed. DNA persisted for up to 5 weeks after their removal in the static experiment and was detected between 9 and 33 days in the flow-through experiment. Sediments and water both proved important for eDNA detection. Crustacean DNA was detected sporadically and unpredictably, whereas non-crustacean DNA was detected more frequently despite their lower densities. We suggest that detecting crustaceans poses a challenge to utilising eDNA approaches for stygofauna monitoring. This is confounded by the scarcity of sequences for stygofauna in reference databases. Further research is needed before eDNA alone can be routinely employed for stygofauna detection.

Synthesizing a novel cerium-modified graphene powder to achieve long-term anticorrosion performance of epoxy powder coatings

Graphene with extremely large specific surface area possesses great loading capacity for various kinds of corrosion inhibitors to obtain long-term anticorrosion properties. In this study, the corrosion inhibitor cerium nitrate was employed to modify graphene on which the cerium species were loaded. The as-synthesized cerium-modified graphene (Ce-Gr) was introduced into epoxy powder coating to provide long-effective corrosion protection on steel. X-ray photoelectron spectroscopy (XPS) analysis implies that cerium species were successfully loaded on graphene in the form of cerium nitrate and cerium oxide. Scanning electron microscopy (SEM) observation exhibited that Ce-Gr improved structural density and reduced the porosity in coating matrix. Electrochemical measurements demonstrated incredibly high impedance values of 1010.5 Ω cm2 for the epoxy powder coatings containing Ce-Gr after immersion in 3.5% NaCl solution for 45 days. Additionally, the smallest average corrosion propagation width of only 0.60 mm on the substrate at scratch after salt spray test, the shorter cathodic disbondment diameter of 3.49 mm and the fewest corrosion oxidation products with extremely low oxygen content of 3 wt% on substrate after salt solution immersion for 120 days implied that the coating with the addition of 0.05 wt% Ce-Gr possessed the most effective corrosion inhibition property to protect the steel substrate for a long period.

Dye wastewater treatment through adsorption-photocatalysis using electroplating sludge-derived NiFe2O4@C catalyst

Electroplating sludge (ES) is classified as HW46 hazardous waste, and its high-value utilization offers superior economic and environmental benefits compared to traditional methods such as thermal treatment, solidification, and landfill. This paper exploits ES's inherent properties while preserving its carbon structure, and a NiFe2O4@C heterojunction catalyst with high adsorption and excellent photocatalytic capabilities is innovatively developed through a novel “one-step” approach. This catalyst is used to activate peroxymonosulfate (PMS) for the degradation of rhodamine B (RhB). Characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the Brunner-Emmet-Teller (BET) method, confirm that the NiFe2O4@C prepared under low-oxygen concentration exhibits a remarkably larger surface area and heterogeneous structure. In dark adsorption experiments lasting 60 min, the NiFe2O4@C achieves an adsorption capacity (Qe) of 295.65 mg/kg. During the subsequent 120-minute photoreaction stage, RhB removal efficiency reaches 96.98 %. Quenching experiments reveal that several active radicals (SO4−, ∙OH, and O2−) play a predominant role in RhB degradation, while nonradicals (1O2 and charge transfer) and high-valent metals also contribute to RhB removal. Density functional theory (DFT) calculations predict RhB molecular sites susceptible to attacks by reactive species. The identification of intermediates using liquid chromatography-mass spectrometry (LC-MS), combined with these theoretical insights, confirmed the main degradation pathways of RhB.

Low-oxygen, uniform, and dense Mo10Nb alloys obtained by combining in situ deoxygenation and mechanical alloying

A high oxygen content, poor uniformity and low density are difficult issues for Mo10Nb alloys prepared by powder metallurgy. In this study, Mo10Nb sintered billets are fabricated by nanocarbon addition and mechanical alloying. The results show that nanocarbon can remarkably reduce the O content of the Mo10Nb sintered billets with a slight increase in the C content. Low-oxygen, uniform, and dense Mo10Nb alloys can be obtained by combining in situ nanocarbon deoxygenation and mechanical alloying. Abrupt changes in stress appear in the stress–strain curves of the Mo10Nb alloy prepared from mixed powder, and the addition of nanocarbon can delay the first stress mutation. The stress changes are mainly caused by the unalloyed Nb containing a high oxygen content. However, the stress change disappears in the stress–strain curve of the Mo10Nb alloy with a low oxygen content, good uniformity and high density.

Impact of Defects and Disorder on the Stability of Ta3N5 Photoanodes

AbstractThe photoelectrochemical performance of Ta3N5 photoanodes is strongly impacted by the presence of shallow and deep defects within the bandgap. However, the role of such states in defining stability under operational conditions is not well understood. Here, a highly controllable synthesis approach is used to create homogenous Ta3N5 thin films with tailored defect concentrations to establish the relationship between atomic‐scale point defects and macroscale stability. Reduced oxygen contents increase long‐range structural order but lead to high concentrations of deep‐level states, while higher oxygen contents result in reduced structural order but beneficially passivate deep‐level defects. Despite the different defect properties, the synthesized photoelectrodes degrade similarly under water oxidation conditions due to the formation of a surface oxide layer that blocks interfacial hole injection and accelerates charge recombination. In contrast, under ferrocyanide oxidation conditions, it is found that Ta3N5 films with high oxygen concentrations exhibit long‐term stability, whereas those possessing lower oxygen contents and higher deep‐level defect concentrations rapidly degrade. These results indicate that deep‐level defects result in rapid trapping of photocarriers and surface oxidation but that shallow oxygen donors can be introduced into Ta3N5 to enable kinetic stabilization of the interface.

Real biofuel and fossil-fuel soot combustion activities in active and passive regeneration of diesel/gasoline particulate filters under different O2/NOx concentrations.

In this work, we aim to investigate and compare the combustion reactivities of real biofuel soot and fossil-fuel soot in the active and passive regeneration conditions of DPF and GPF through temperature-programmed oxidation (TPO). Higher reactivity of biofuel soot is achieved even under GPF conditions with extremely low oxygen concentration (~ 1%), which provides a great potential for low-temperature regeneration of GPF. Such a result is mainly attributed to the low graphitization and less surface C = C groups of biofuel soot. Unfortunately, the presence of high-content ashes (~ 47%) and P impurity in real biofuel soot hinder its combustion reactivity. TPO evidences that the O2/NOX-lacking conditions in GPF are key factors to impact the combustion of soot, especially fossil-fuel soot. This work provides some useful information for understanding real biofuel and fossil-fuel soot combustion in GPF and DPF regeneration and further improvement in filter regeneration process.

Integrating physical knowledge and artificial intelligence approaches for simulation and optimization of direct urea fuel cell

Direct urea fuel cell (DUFC) has recently gained attention as a potentially effective fuel cell because of urea’s ease of use, low-cost, high-energy density, and toxicity-free nature. To develop a fast and accurate mathematical tool to model and optimize the performance of DUFC, this study, for the first time, combined the kinetic model and artificial intelligence approaches. Accordingly, an artificial neural network (ANN) model was developed based on the synthetic datasets produced from the verified kinetic model and then was optimized by particle swarm optimization to determine the optimal conditions for DUFC. The peak power density output and substrate-based energy recovery were chosen as the target functions that depend on several fundamental operating and designing parameters (i.e., types of catholyte, membrane thickness, diffusion layer thickness and porosity, feeding flow rate, temperature, urea and KOH concentrations). Along with significantly reducing the computational simulation time to the kinetic model (from 1500 s to 2 s), the proposed approach exhibited superior accuracy compared to the response surface methodology. With nickel nanoparticles as the anode catalyst material and pure oxygen as the catholyte, the highest power density output and energy recovery from DUFC were predicted at 15.1 mW/cm2 and 19.6 %, respectively. On the other hand, with the natural air supply, the optimal power density and energy recovery values were only 14.4 mW/cm2 and 18.9 %, respectively, due to lower oxygen concentration. These poor performances suggest that more efficient catalyst materials for DUFC need to be further investigated and applied.

730 nm Light‐Induced Cleavage of BODIPY Photocages via Entropy‐Driven Triplet Sensitization

AbstractLight‐activated drug delivery systems allow precise spatiotemporal control of a drug release process. However, safe and efficient drug release activation needs a low‐power nonpulsed red/near‐infrared light with high tissue penetration depth. Nevertheless, such systems remain a challenge. Herein, a self‐assembled nanovehicle made of 2,6‐diiodo‐B‐dimethyl‐boron dipyrromethene (BODIPY)‐based photocleavable trigonal molecules bearing Pt(II) meso‐tetraphenyltetranaphthoporhyrin photosensitizer and a fluorescent release marker Nile Red in hydrophobic core is introduced. The system employs endothermic triplet–triplet energy transfer between the photosensitizer and the trigonal molecule, leading to the cleavage of the trigonal molecule followed by cargo release. This allows to engage 730 nm light to cleave BODIPY photoremovable protecting groups (PPGs) instead of 530 nm light that would be needed for direct photocage excitation. Therefore, the approach unleashes the desired activation of drug release via photocleavage with longer wavelengths (within the phototherapeutic window) without any chemical modification of the PPGs. Cell studies demonstrate fast intracellular uptake of the nanovehices by PC3 human prostate cancer cells with accumulation in lysosomes in 2 h. Light irradiation at 730 nm on nanovehicles dispersed in cell media leads to payload release. Remarkably, the system exhibits higher release efficiency at low oxygen concentration than at ambient thus allowing to tackle aggressive hypoxic solid tumors.

P-165 Benefits of ultra-low oxygen tension (2%) in patients with low quality embryos or previous arrest: the patient as its own control

Abstract Study question Is reduction in oxygen tension from 5% to 2% after D3 of extended culture beneficial for blastocyst development in patients with previous failed culture? Summary answer Ultra-low oxygen tension in extended culture improves blastocyst development (overall blastulation rate OBR), quality (top blastulation rate TPR) and increases the pregnancy rate (PR). What is known already The practice ESHRE guidelines recommends human embryo culture at low oxygen concentrations (2-8%). Traditionally atmospheric conditions (20% O2) were used but better outcomes were observed at low monophasic 5% O2. Human embryo leaves the oviduct (5-7% O2) to cross the uterus-tubal junction around D3-4 and reaches the uterin ultra-low O2 tension (2%). This decreasing gradient coincides with the shift from pre-compaction oxidative phosphorylation in the oviduct, to post-compaction glycolysis in the uterus. Few studies with ultra-low 2% O2 incubation suggested that the best O2 level may be stage-dependent and its reduction after D3 may be a more physiological approach. Study design, size, duration Prospective observational study in a single private hospital during 2023. 71 patients experienced a failed cycle of extended culture (n = 29 cIVF, n = 37 ICSI and n = 5 Sibling oocytes) with a poor embryo quality and low OBR, under standard monophasic 5% O2 incubation. In the subsequent cycle for these 71 patients (n = 24 cIVF and n = 46 ICSI and n = 1 Sibling oocytes) the O2 level was reduced to 2% from D3 onwards. Participants/materials, setting, methods After a failed extended culture, considered as the control cycle, the patients were enrolled for the study. Blastocysts were rated by Gardner’s classification. In the control cycle embryos were cultured under monophasic 5% O2 until D6. In the subsequent cycle embryos were cultured under 5% O2 until D3 and in ultra-low 2% O2 from D3 to D6. Sage 1-Step™ media was used for both cycles. The statistical analyses were done by chi-square and fisher test. Main results and the role of chance 71 patients were included in the study regardless of age, indication or technique. Each patient was its own control. The mean age was not different between the 2 groups (36.5±4 vs 37.2±4) but the attempt rank was logically statistically higher in the study cycle (2.1±1.4 vs 3.4±1, p&amp;lt;0.001). Oocyte maturity (75% vs 76.4%) and fertilization rate (66.8 vs 70.3%) were similar between groups. The average embryo quality at D3 was poor in both groups. OBR and TBR (40.7% vs 52.4%, p=0.004 and 15.8% vs 37.5%, p&amp;lt;0.001) were statistically higher after culture in ultra-low O2 conditions. Extended culture failure with absence of usable blastocyst (57.7% vs 19.7%, p&amp;lt;0.001) was statistically lower in ultra-low incubation group and the pregnancy rate PR per cycle (3.6% vs 25%, p=0.004) was seven fold higher after ultra-low culture. Limitations, reasons for caution The small size of the sample needs to be expanded in order to confirm the encouraging findings in a larger population. The study will continue during 2024 and will compel the live birth rate and the cumulative live birth rate. Wider implications of the findings Providing embryos with the most physiologic culture system would improve IVF cost-effectiveness and a better infertility management. Embryo energetic adaptation to suboptimal conditions results in impaired viability and lower pregnancy rates. In our study extended culture of low-quality embryos under 2% O2 after D3 yielded better culture and pregnancy outcomes. Trial registration number NA

Tectono‐sedimentary history of the upper Cedar Mountain Formation, Central Utah, USA

ABSTRACTCurrent investigations into the Albian–Cenomanian sedimentary record within the Western Interior have identified multiple complex tectono‐sedimentary process–response systems during the ongoing evolution of North America. One key sedimentary succession, the upper Cedar Mountain Formation (Short Canyon Member and Mussentuchit Member), has historically been linked to various regionally and continentally significant tectonic events, including Sevier fold‐and‐thrust deformation. However, the linkage between the Short Canyon Member and active Sevier tectonism has been unclear due to a lack of high‐precision age constraints. To establish temporal context, this study compares maximum depositional ages from detrital zircons recovered from the Short Canyon Member with that of a modified Bayesian age stratigraphic model (top‐down) to infer that the Short Canyon Member was deposited at ca 100 Ma, penecontemporaneous with rejuvenated thrusting across Utah [Pavant (Pahvant), Iron Springs and Nebo thrusts]. These also indicate a short depositional hiatus with the lowermost portion of the overlying Mussentuchit Member. The Short Canyon Member and Mussentuchit Member preserve markedly different sedimentary successions, with the Short Canyon Member interpreted to be composed of para‐autochthonous orogen–transverse (across the Sevier highlands) clastics deposited within a series of stacked distributive fluvial fans. Meanwhile, the muddy paralic Mussentuchit Member was a mix of orogen–transverse (Sevier highlands and Cordilleran Arc) and orogen–parallel basinal sediments and suspension settling fines within the developing collisional foredeep. However, the informally named last chance sandstone (middle sandstone of the Mussentuchit Member) is identified as an orogen–transverse sandy debris flow originating from the Sevier highlands, similar to the underlying Short Canyon Member. During this phase of landscape evolution, the Short Canyon Member – Mussentuchit Member depocentre was a sedimentary conduit system that would fertilize the Western Interior Seaway with ash‐rich sediments. These volcaniclastic contributions, along with penecontemporaneous deposits across the western coastal margin of the Western Interior Seaway, eventually would have lowered oxygen content and resulted in a contributing antecedent trigger for the Cenomanian–Turonian transition Oceanic Anoxic Event 2.

Sustainable Plasma‐Catalytic Nitrogen Fixation with Pyramid Shaped μ‐Electrode DBD and Titanium Dioxide

AbstractThis research explores the potential of electric field enforcement in dielectric barrier discharge using specially designed pyramid‐shaped μ‐electrodes for a plasma‐assisted nitrogen fixation process. The obtained results are compared under varying conditions, including the presence and absence of titanium dioxide ( ), different oxygen concentrations in the nitrogen‐feeding gas, and residence time. The results demonstrate that the μ‐electrodes lead to an enhancement of nitrogen oxidation, which is further intensified by . The introduction of 60–70 % oxygen with nitrogen achieves the highest level of production. The synergistic effect of plasma and the catalytic effect of increase the rate of production by 20 %, resulting in a 23 % increase in energy yield. The introduction of leads to a sharp increase in production even at lower oxygen concentrations. The crucial role played by ultraviolet light‐induced electron‐hole pairs in is highlighted to promote nitrogen oxidation. Nevertheless, it is crucial to emphasize that prolonged residence times may cause the photocatalytic effect to generate alternative byproducts rather than , consequence of excessive oxidation that could prove counterproductive. These findings emphasize the potential of plasma‐assisted nitrogen fixation technology in reducing energy costs and meeting the growing demand for sustainable nitrogen‐based fertilizers.

Diffusion characteristics of indoor pollutants from incense sticks combustion in Tibetan Plateau buildings: An experimental study

Incense burning, a common practice among ethnic Tibetans in Qinghai-Tibet Plateau of China, generates pollutants that can impact indoor air quality and, subsequently, human health. In this paper, we investigate the diffusion characteristics of four prevalent pollutants emitted during the burning of local Tibetan incense under low-pressure conditions specific to the plateau region. The diffusion behavior of these incense burning pollutants deviates from that observed under standard atmospheric pressure due to the unique conditions prevailing at high altitudes. The research results reveal that the primary pollutants released during Tibetan incense combustion are carbon dioxide, inhalable PM2.5, and PM10. Furthermore, ambient temperature exerts a substantial influence on the concentration of pollutants emitted during incense burning. A 6 °C increase in ambient temperature results in a 1.17-fold rise in the combustion rate. Consequently, higher temperatures correspond to larger diffusion coefficients, increased gas diffusion rates, and elevated pollutant concentrations at equivalent combustion times. Simultaneously, the low oxygen content characteristic of plateau regions has a notable impact on the diffusion rate of gaseous pollutants. This study of pollutant concentration and diffusion characteristics during incense burning offers valuable insights for determining the minimum ventilation rate in plateau areas.

Effect of cooling rate on the precipitation characteristics and growth mechanism of Bi3Ni in liquid lead‑bismuth eutectic

Austenitic stainless steel is a promising candidate structural material for direct contact components with lead‑bismuth eutectic (LBE) in lead-cooled fast reactor (LFR). However, the preferential dissolution of Ni from austenitic steels at low oxygen concentrations will lead to the precipitation of Ni-containing phases in the low-temperature parts of reactors, which has a risk of pipe clogging. In this paper, three samples, comprising one extracted from a corrosion tank after prolonged operation and two prepared, respectively, by quenching in liquid nitrogen and cooling in the furnace, were obtained to investigate the effect of cooling rate on the precipitation characteristics and growth mechanism of Bi3Ni that forms by the reaction of dissolved Ni and Bi in LBE. The results showed that rod-like Bi3Ni was found in all three Ni-containing LBE samples. As the cooling rate increased, the width of Bi3Ni decreased. The Bi3Ni in all three samples displayed a pseudo-hexagonal prismatic shape and had a typical faceted growth character; the cooling rate had no effect on the morphology of them. The crystallographic analysis showed that the growth axis of Bi3Ni was in the 〈010〉 direction, and the prism planes were composed of {001} and {101}. In addition, the precipitation of Bi3Ni inevitably increased the content of Pb7Bi3, which would in turn enhance the volumetric expansion of solid LBE samples. For the growth mechanism, Bi3Ni phases were controlled by the screw dislocation mechanism, with the step growth rate of the dislocation core being greater than that of the outer edges. Given the low cooling rate and low Ni content in the LBE coolant of reactors, the precipitation of Bi3Ni with a rod-like morphology seems to be inevitable.

Manganese (III) phthalocyanine complex nanoassembly: Oxygen-Independent generation of superoxide radicals and singlet oxygen for ultrasound-augmented chemodynamic therapy

Singlet oxygen (1O2), an excellent reactive oxygen species (ROS) for tumor therapy, has garnered significant attention recently. However, its production is hindered by the low oxygen content in solid tumors characterized by hypoxia. Consequently, it is urgent to develop an O2-independent generator. In this study, we present a novel nano-assembly composed of manganese (Ⅲ) phthalocyanine complex (MnClPc) encapsulated by human serum albumin (MnClPc@HSA). MnClPc@HSA serves as a conventional sonosensitizer, facilitating the conversion of O2 to 1O2 under ultrasonic stimulation (US). Moreover, MnClPc@HSA enables the conversion of endogenous hydrogen peroxide (H2O2) within tumor to superoxide radical (·O2–) and 1O2 and further enhanced by US. This O2-independent generation of multiple ROS by MnClPc@HSA overcomes the limitations imposed by tumor hypoxia, while inducing immunogenic cell death (ICD) and enhancing the infiltration of T cells as well. When combined with conventional PD-L1 immunotherapy, this approach effectively inhibits the proliferation of distal and lung-metastatic tumors, while concurrently eliminating primary tumors in the bilateral-tumor model of 4 T1 tumor-bearing mice.

Analysis of stage parameters of low-temperature oxidation of water-soaked coal based on kinetic principles

Mine fires caused by spontaneous coal combustion are major disasters in coal mines. The staged oxidation kinetic parameters of various coal samples at oxygen concentrations of 21 %, 15 %, 10 %, 5 %, and 3 % were analyzed using a programmed temperature testing system. Herein, the temperature increase rate of coal, the temperature difference between the furnace and coal, and the oxygen consumption characteristics were obtained. Based on the amount of CO produced and the temperature sensitivity coefficient, three characteristic temperatures and four stages of low-temperature oxidation (LTO) were identified. The results showed that at a critical temperature (TC), the amount of CO gas released from the coal samples increased with increasing oxygen concentration, and the difference in the oxygen consumption rate increased. After the limit temperature (Tu), the amount of CO gas increased steadily, and the increase in the oxygen consumption rate stagnated. CO production, the maximum heating rate, and the maximum heat release rate were positively correlated with the oxygen concentration. As the oxygen concentration increased, the activation energy during the oxygen absorption stage gradually decreased. The average reaction enthalpy (ΔH) of pre-oxidized water-immersed coal was 19.37 kJ/kg greater than that of raw coal. The equation for the conservation of energy of the coal oxidation warming process was normalized. The theoretical values of the awakening stage and the stable stage were τν and τν (1-B), respectively. When B was >1, pre-oxidized water-immersed coal at a low oxygen concentration was prone to crossover points during the oxygen absorption stage, which increased the risk of coal spontaneous combustion (CSC). The research results could provide a theoretical basis for the staged control of the spontaneous combustion of water-immersed coal in goaf areas.

In-situ two-dimensional temperature measurements using x-ray fluorescence spectroscopy in laminar flames with high silica particle concentrations

X-ray fluorescence spectroscopy (XRF) was used to measure temperatures and study mixing, for the first time in silica particle synthesis flames. Hexamethyldisiloxane (HMDSO) and trimethylsilanol (TMSO) were the particle precursors. A multi-element diffusion burner was used to produce a flat methane flame, and the precursors, dilute in inert gas, were injected via a central jet. Krypton was the fluorescent medium at 3.2 % concentration by volume. Scans with Kr in the central flow and not in the main flow were made to assess the mixing effects between the central and main gas flows. When HMDSO or TMSO were added, a secondary diffusion flame formed between the jet and the main methane flame. The results revealed a dramatic change in the centerline temperature profile of the jet gases when HMDSO or TMSO were added. The main methane flame stoichiometry also affected the temperature profiles. The results show HMDSO and TMSO reactions are initiated in a low-temperature and low-oxygen concentration region of the jet where thermal decomposition is not expected to be significant. Reaction of the particle precursors is therefore attributed to radical transport from the main methane flame. In the current work, particle number densities of up to 270 g/m3 locally are estimated. Thus, the study also demonstrates the capability of the XRF technique for high spatial fidelity measurements in flames with high concentrations of condensed-phase particles, leveraging the attribute that the XRF signal is generally not impacted by condensed-phase interferences. The observations and data obtained in this study inform likely reaction pathways for this important class of siloxane compounds.

Limiting the lattice oxygen impurities to obtain high thermal conductivity aluminum nitride ceramics

Currently, the lattice oxygen is the key factor affecting the thermal conductivity of AlN ceramics. In this paper, three methods are proposed to limit lattice oxygen, namely reducing the original powder oxygen content, changing the debinding atmosphere, and extending the sintering time. The results show that the low powder oxygen content and protective debinding atmosphere alter the carbon and oxygen content, and further promote the formation of the Y4Al2O9 (YAM) phase. The generated YAM phase can effectively reduce the lattice oxygen in terms of thermodynamics. Prolonged high temperatures can provide kinetic conditions to reduce the lattice oxygen to 0.0343 wt%. In addition, morphological changes of the phase at the grain edges and their influence on the mechanical properties were noted. Finally, AlN ceramics with a thermal conductivity of 220 W m−1 K−1 and a flexural strength of 340 MPa were obtained. This study can provide a valuable reference for the industrial production of AlN ceramics.