Active Oxygen Content Research Articles

Enhanced NOx-assisted soot combustion by cobalt doping to weaken mullite Mn-O bonds for lattice oxygen activation

Catalytic combustion is widely regarded as the most efficient technique for removing soot particulates from diesel engine exhaust, with its efficiency largely dependent on the performance of catalysts. In this study, a series of YMn1−xCoxO5-ζ catalysts were synthesized using a hydrothermal method to investigate their catalytic properties in soot oxidation. Among these catalysts, YMCo-0.2 exhibited the highest catalytic activity, achieving 90 % soot conversion at 392 °C and demonstrating robust tolerance in the presence of water vapor and SO2. Structural characterization revealed that Co doping did not alter the fundamental crystal structure of YMn2O5 mullite. Through some characterization comprehensive analysis, and DFT calculations further supported the experimental findings, indicate that Co substitution significantly increased the lattice oxygen mobility and surface active oxygen content. Compared to the surface lattice oxygens at other positions, the weakening of the Mn-O bond results in the lattice oxygens in the Co-O-Mn4+ sites in the catalysts exhibiting higher reactivity. Additionally, the catalyst displayed strong NO and O2 adsorption and activation capabilities, indicating its potential for efficient NOx-assisted soot combustion. This study provides insights for designing and optimizing mullite catalysts for soot combustion.

CaMKII Exacerbates Doxorubicin-Induced Cardiotoxicity by Promoting Ubiquitination Through USP10 Inhibition.

Doxorubicin (DOX) is an effective anticancer drug, but it has a problem of cardiotoxicity that cannot be ignored. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is tightly associated with the pathological progression of DOX-induced cardiotoxicity. Ubiquitin-specific protease 10 (USP10) plays an important role in many biological processes and cancers. However, its association with DOX-induced cardiotoxicity and CaMKII remains unclear. H9C2 cells, HL-1 cells and C57BL/6 mice were used to establish the DOX-induced cardiotoxicity model, and the CaMKII-specific inhibitor KN-93 and USP10 specific inhibitor Spautin-1 were used to observe the CaMKII and USP10 effect. In cell experiments, CCK-8 method was used to assess cell viability, LDH kit was used to assess lactate dehydrogenase expression, DCFH-DA staining was used to observe changes in active oxygen content, TUNEL staining was used to observe cell apoptosis, and Western blotting method was used to detect relevant protein markers. The expression of p-CaMKII and USP10 was assessed by immunofluorescence staining. In animal experiments, mouse echocardiograph was used were used to evaluate cardiac function, and HE staining and Masson staining were used to evaluate myocardial injury. Cardiomyocyte apoptosis was detected by TUNEL staining. Western blotting method was used to detect relevant protein markers. Our results demonstrated that activation of CaMKII and inhibition of USP10 pathway related to DOX-induced cardiotoxicity. Inhibition of CaMKII with KN-93 ameliorated DOX-induced cardiac dysfunction and cytotoxicity. In addition, CaMKII inhibition prevented DOX-induced apoptosis and ubiquitination. Furthermore, CaMKII inhibition increased USP10 expression in DOX-treated mouse hearts, H9C2 cells and HL-1 cells. At last, the USP10 inhibitor, Spautin-1, blocked the regulatory effect of CaMKII inhibition on apoptosis and ubiquitination in DOX-induced cardiotoxicity. Our findings revealed that DOX-induced myocardial apoptosis and activated CaMKII through cellular and animal levels, while providing a novel probe into the mechanism of CaMKII action: promoting ubiquitination by inhibiting USP10 aggravated apoptosis.

Peroxidation of methyl ethyl ketone catalyzed by UiO-66 and the thermal stability analysis

The synthesis of methyl ethyl ketone peroxide (MEKP) generally belongs to the homogeneous strong acid catalysed process. Acid is corrosive to the equipment, cannot be reused and thus has a large amount of wastewater to be post-treated and needs high treatment cost. The heterogeneous catalytic synthesis of organic peroxides is gaining more and more attention. In this study, methyl ethyl ketone peroxide was prepared from butanone oxidized by hydrogen peroxide and in the presence of UiO-66 as the catalyst. Under the conditions that the molar ratio of H2O2 to methyl ethyl ketone (MEK) is 2, the mass ratio of UiO-66 to MEK is 0.045, the reaction temperature is 30 °C, and the reaction time is 70 min, the active oxygen content of the product reaches 10.81 %, and the main products are methyl ethyl ketone peroxide and its oligomers. The thermal decomposition heat and activated energy are 748 J·g−1 and 101 kJ·mol−1 based on the thermogravimetric-differential scanning calorimetry (TG-DSC) determination. Finally, after four cycles, uio-66 still had 70.2 % yield, and XRD and FTIR after the cycles proved the good stability of the catalyst. The study provides a new way for the production of methyl ethyl ketone peroxide by heterogeneous catalytic oxidation.

Removal of formaldehyde from indoor air by potted Sansevieria trifasciata plants: dynamic influence of physiological traits on the process.

Plant-based removal of indoor formaldehyde is a widely studied method, yet little is known about the dynamic changes in this process. In this study, potted Sansevieria trifasciata Prain plants were exposed to 5-ppm formaldehyde gas concentration for 7days. The results showed that formaldehyde exposure led to plant stress, affected photosynthesis, and damaged membrane lipids, as evidenced by a decrease in chlorophyll content, an increase in Chl a/b ratio and malondialdehyde content. However, the formaldehyde removal ability of the plants increased over the first 5days, peaking at 18.02mgh-1kg-1 dry weight on the 5th day. This trend was correlated with changes in various indicators in the plant roots, including phytohormone and antioxidant enzymes. Notably, catalase activity in the roots behaved differently from other indicators. The indicators in the leaves showed turning points around the 3rd day due to the direct exposure of the leaves to formaldehyde. The relative abundance of endophytes indicated an increase in plant growth-promoting bacteria, which helped the plant cope with formaldehyde stress. The study suggests that under formaldehyde stress, plants manage active oxygen content by increasing phytohormones and regulating redox reactions. This enhances their tolerances to formaldehyde, thereby improving their ability to remove formaldehyde and aiding recovery after formaldehyde exposure.

Structure and molecular-level transformation for oxidation of effluent organic matters by manganese oxides

As important organic components in water environments, effluent organic matters (EfOMs) from wastewater treatment plants are widely present in Mn-rich environments or engineered treatment systems. The redox interaction between manganese oxides (MnOx) and EfOMs can lead to their structural changes, which are crucial for ensuring the safety of water environments. Herein, the reactivities of MnOx with EfOMs were evaluated, and it was found that MnOx with high specific surface area, active high-valent manganese content and lattice oxygen content (i.e., amorphous MnO2) possessed stronger oxidizing ability towards EfOMs. Accompanying by EfOMs oxidation, Mn(IV) and Mn(III) were reduced into Mn(II), with Mn(III) as the significant active species. Through molecular-level transformation analysis by ultrahigh mass spectrometry (FT-ICR MS), the highly reactive compounds in EfOMs were clearly determined to be that with more aromatic and unsaturated structures, especially lignin-like compounds (the highest content in EfOMs (over 60 %)). EfOMs were oxidized by amorphous MnO2 into products with lower humification index (0.60 vs. 0.46), smaller apparent molecular weight (386.94 Da vs. 368.68 Da), and higher biodegradability (BOD5/COD: 0.12 vs. 0.78). This finding suggested that redox reactions between MnOx and EfOMs might alter their abiotic and biotic behaviors in receiving water environments.

Constructing asymmetric active Fe3+-OV-Mn4+ sites at the Fe2O3-MnO2 interface for low-temperature soot combustion

Promoting the generation of reactive oxygen species by adjusting the strength of metal-oxygen bonds and constructing interfacial active sites has been proven to effectively enhance soot combustion. Herein, Fe2O3-MnO2 bimetallic oxides (FMO) with a heterogeneous interface were prepared using a simple PBA (Prussian blue analogue) derivation method. The catalysts exhibited superior active oxygen content and strong electron transport capacity. The Fe3+-OV-Mn4+ structure, an asymmetric oxygen vacancy, formed at the interface, and the strength of the metal-oxygen bonds was further regulated at different calcination temperatures, significantly activating lattice oxygen. The FMO-HA catalyst showed the highest activity, with soot conversion temperatures reaching 90 % at 289 °C under tight contact and 382 °C under loose contact. This work offers a dual regulatory strategy to enhance the production of reactive oxygen species and proposes a rational design for high-performance catalysts for soot combustion.

Boosting the removal of diesel soot particles by regulating the Pr−O strength over transition metal doped Pr6O11 catalysts

The content of active lattice oxygen and oxygen vacancies is crucial for the catalytic oxidation of soot. Herein, we adjust the Pr-O bond strength in Pr6O11 by doping several common transition metals (Mn, Fe, Co, Ni) to promote the formation of oxygen vacancies and the activation of lattice oxygen. This strategy does not compromise its crystal structure, allowing for improved catalytic performance while maintaining stability. The Mn-doped Pr6O11 catalyst shows the best soot catalytic oxidation performance. Its T50 (the temperature of soot conversion reaching 50 %) value is 396 °C under loose contact. Further characterizations and density functional theory (DFT) calculations demonstrate that PMO possesses a large specific surface area. Additionally, the weakening the strength of the Pr-O bond leaded to an increase in oxygen vacancies, which in turn enhanced the redox ability of catalyst. This work will provide a reference for the development of Pr-based catalysts for soot combustion.

Physiological, biochemical and transcriptomic insights into the mechanisms by which molybdenum mitigates cadmium toxicity in Triticum aestivum L

There are many heavy metal stresses in agricultural biological systems, especially cadmium (Cd) stress, which prevent the full growth of plants, lead to a serious decline in crop yield, and endanger human health. Molybdenum (Mo), an essential nutrient element for plants, regulates plant growth mainly by reducing the absorption of heavy metals and protecting plants from oxidative damage. The aim of this study was to determine the protective effect of Mo (1 μM) application on wheat plants under conditions of Cd (10 μM) toxicity. The biomass, Cd and Mo contents, photosynthesis, leaf and root ultrastructure, antioxidant system, and active oxygen content of the wheat plants were determined. Mo increased the total chlorophyll content of wheat leaves by 43.02% and the net photosynthetic rate by 38.67%, and ameliorated the inhibitory effect of cadmium on photosynthesis by up-regulating photosynthesis-related genes and light-trapping genes. In addition, Mo reduced the content of superoxide anion (O2•—) by 16.55% and 31.12%, malondialdehyde (MDA) by 20.75% and 7.17%, hydrogen peroxide (H2O2) by 24.69% and 8.17%, and electrolyte leakage (EL) by 27.59% and 16.82% in wheat leaves and roots, respectively, and enhanced the antioxidant system to reduce the burst of reactive oxygen species and alleviate the damage of Cd stress on wheat. According to the above results, Mo is considered a plant essential nutrient that enhances Cd tolerance in wheat by limiting the absorption, accumulation and transport of Cd and by regulating antioxidant defence mechanisms. Environmental ImplicationCadmium (Cd)，is one of the most toxic heavy metals in the environment, and Cd pollution is a global environmental problem that threatens food security and human health. Molybdenum (Mo), as an essential plant nutrient, is often used to resist environmental stress. However, the mechanism of Mo treatment on wheat subjected to Cd stress has not been reported. In this study, we systematically analysed the effects of Mo on the phenotype, physiology, biochemistry, ultrastructure and Cd content of wheat subjected to Cd stress, and comprehensively analysed the transcriptomics. It not only reveals the mechanism of Mo tolerance to Cd stress in wheat, but also provides new insights into phytoremediation and plant growth in Cd-contaminated soil.

Determination of the possibility of the synthesis of Zn-Al layered double hydroxides, intercalated with peroxyanions, as a perspective solid disinfectant

Infectious diseases in the modern world pose a significant threat to humanity in the form of epidemics and pandemics. To prevent and combat them, it is necessary to carry out antiseptic and disinfectant treatments of various environments, household and industrial surfaces, as well as wounds of various origins. Double-layer hydroxides intercalated with peroxyanions as active oxygen compounds are promising materials for this. In order to determine the possibility of obtaining Zn-Al double-layer hydroxide intercalated with peroxylactic acid anions, samples were synthesized by the method of chemical co-precipitation in the presence of peroxylactic acid at controlled pH (8, 10) and t=20 ℃. The properties of the synthesized samples were investigated. The content of active oxygen (in terms of H2O2) was determined by the method of iodometric titration with the calculation of the percentage of hydrogen peroxide that was intercalated in double layered hydroxides, remained in the mother solution or was lost. The crystal structure was studied by X-ray phase analysis, the yield of samples was determined gravimetrically, and sedimentation was determined by measuring and normalizing the thickness of the sediment layer. It was found that the samples synthesized at pH=8 and 10 are biphasic and consist of an oxide phase and a double-layer hydroxide phase. The determined content of active oxygen (in terms of H2O2) in the samples synthesized at pH=8 (0.533 %) and at pH=10 (0.876 %) confirms the success of the synthesis of Zn-Al-peroxylactate double layered hydroxides. Synthesis at elevated pH is promising. A low percentage of H2O2 intercalation was revealed – 4.03–6.54 %, the majority of hydrogen peroxide (82.36-94.44 %) remains in the mother solution. The yield of the synthesized samples was determined to be 61.9 % and 79.5 % at synthesis pH of 10 and 8, respectively. The sedimentation properties of the samples were studied and their improvement was shown when the pH of the synthesis was increased

Integrative leaf anatomy structure, physiology, and metabolome analyses revealed the response to drought stress in sainfoin at the seedling stage.

Sainfoin (Onobrychis viciaefolia) is a vital legume forage, and drought is the primary element impeding sainfoin growth. The anatomical structure, physiological indexes, and metabolites of the leaves of sainfoin seedlings with a drought-resistant line of P1 (DRL) and a drought-sensitive material of 2049 (DSM) were analyzed under drought (-1.0 MPa) with polyethylene glycol-6000 (PEG-6000). The leaf anatomy was studied by the paraffin section method. The related physiological indexes were measured by the hydroxylamine oxidation method, titanium sulfate colorimetric method, thiobarbituric acid method, acidic ninhydrin colorimetric method, and Coomassie brilliant blue method. The metabolomics analysis was composed of liquid chromatography tandem high-resolution mass spectrometry (LC-MS/MS). The results revealed that the thickness of the epidermis, palisade tissue, and sponge tissue of DRL were significantly greater than those of DSM. The leaves of DRL exhibited lower levels of superoxide anion (O2 •-) production rate, hydrogen peroxide (H2O2) content, and malondialdehyde (MDA) content compared with DSM, while proline (Pro) content and soluble protein (SP) content were significantly higher than those of DSM. A total of 391 differential metabolites were identified in two samples. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed that the primary differential metabolites were concentrated into the tyrosine metabolism; isoquinoline alkaloid biosynthesis; ubiquinone and other terpenoid quinone biosynthesis; neomycin, kanamycin, and gentamicin biosynthesis; and anthocyanin biosynthesis metabolic pathways. Compared with DSM, DRL had more complete anatomical structure, lower active oxygen content, and higher antioxidant level. The results improved our insights into the drought-resistant mechanisms in sainfoin.

S-ABA Enhances Rice Salt Tolerance by Regulating Na+/K+ Balance and Hormone Homeostasis.

In order to explore the regulating role and the physiological and biochemical mechanisms of trans-abscisic acid (hereinafter referred as S-ABA) in the process of rice growth and development under salt stress, we took Chaoyou 1000 and Yuxiangyouzhan as materials and set up three salt concentration treatments, CK0 (Control treatment), N1 (50 mmol L-1 NaCl), and N2 (100 mmol L-1 NaCl), in potted trials; we aimed to study the mechanism of rice's response to salt stress from the perspective of agricultural traits and physiological biochemicals and to improve rice's resistance to salt stress through exogenously applying the regulating technology of S-ABA. The following results were obtained: Under salt stress, the growth of rice was significantly suppressed compared to CK0, exhibiting notable increases in agricultural indicators, photosynthesis efficiency, and the NA+ content of leaves. However, we noted a significant decrease in the K+ content in the leaves, alongside a prominent increase in NA+/K+ and a big increase in MDA (malondialdehyde), H2O2 (hydrogen peroxide), and O2- (superoxide anion). This caused the cytomembrane permeability to deteriorate. By applying S-ABA under salt stress (in comparison with salt treatment), we promoted improvements in agronomic traits, enhanced photosynthesis, reduced the accumulation of NA+ in leaves, increased the K+ content and the activity of antioxidant enzymes, and reduced the active oxygen content, resulting in a sharp decrease in the impact of salt stress on rice's development. The application of S-ABA decreased the endogenous ABA (abscisic acid) content under salt stress treatment but increased the endogenous GA (gibberellin) and IAA (indole acetic acid) contents and maintained the hormonal homeostasis in rice plants. To summarize, salt stress causes damage to rice growth, and the exogenous application of S-ABA can activate the pouring system mechanism of rice, suppress the outbreak of active oxygen, and regulate NA+/K+ balance and hormone homeostasis in the blades, thus relieving the salt stress.

Structure elucidation and anticancer activity of a heteropolysaccharide from white tea

White tea, one of the six traditional teas in China, is made only through natural withering and low-temperature drying processes. It demonstrates diverse pharmacological and health-promoting effects, including antioxidant, antiviral, anticancer, and hypolipidemic activities. Despite the significance of polysaccharides in white tea leaves, their fine structure and physiological functions remain unexplored. In this study, the polysaccharide fragment WTP-80a with anticancer activity was isolated and purified from white tea through water extraction, alcohol precipitation, DEAE-52 ion exchange column chromatography, and sephacryl S-200 dextran gel column chromatography. WTP-80a exhibited a molecular weight of 1.14 × 105 Da and consisted of galactose (Gal), arabinose (Ara), rhamnose (Rha), and glucuronic acid (Glc-UA). The main chain skeleton of WTP-80a contained 3,6)-β-Galp-(1→, 3)-α-Galp-(1→, 5)-α-Araf-(1 → and 3)-α-Glcp-UA-(1→. Branch chains included α-Araf-(1 → and β-Rhap-(1 → connected to the C3 and C6 positions of →3,6)-β-Galp-(1→, respectively. In vitro anticancer experiments revealed that WTP-80a effectively hindered the proliferation, colony formation, migration, and invasion of B16F10 cells. Additionally, it induced apoptosis in B16F10 cells by blocking the G2/M phase, increasing active oxygen content, and reducing mitochondrial membrane potential. These findings provide a solid theoretical foundation for the application of white tea polysaccharides as anticancer products.

Sustained release of a novel bilayer packaging film loaded with binary microemulsion of melatonin/pummelo essential oil and its regulation of postharvest energy metabolism in Agaricus bisporus

Bio-based active soft packaging materials have excellent potential to alleviate existing environmental problems caused by conventional packaging products and delay the postharvest aging of fruit and vegetables. In this study, a novel bilayer packaging film (G/T-M-E) of glutenin/tamarind gum loaded with binary microemulsion of melatonin/pummelo essential oil was prepared. The results indicated that the G/T-M-E packaging had superior barrier and mechanical properties. Importantly, the melatonin (MT) and pomelo essential oil (PEO) loaded in soft packaging had good sustained-release properties, which could ensure release characteristics in different food simulants. Among them, MT had the highest release efficiency in 10% ethanol, while PEO is more easily released in distilled water. Meanwhile, MT and PEO migrated from the packaging film from the inside-out via different diffusion effects, which was beneficial for the synergistic effect of active ingredients. G/T-M-E maintained a higher level of ATP of white mushrooms, greater energy charge levels and higher activity of succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO). The energy charge (EC) of mushrooms packaged in G/T-M-E was as high as 0.65, which was 1.43 times higher than that of the G/T treatment group on day 12. The SDH and CCO activity of the G/T-M-E treatment group were 2.62 and 2.19 times higher than those of the G/T group on day 10, respectively. Overall, the G/T-M-E film improved the electron transfer efficiency, reduced the excess active oxygen content, maintained the high energy state, regulated the tricarboxylic acid cycle and electron transport chain pathways, indicating that the film has the active potential to regulate the energy state of postharvest mushrooms.

The effect of hydrothermal aging on Mn2O3/Cu-SSZ-39 composite catalysts for selective catalytic reduction of NOx by NH3

The latest generation of fuel-efficient engines produces exhaust at cooler temperatures, highlighting a need for enhancement in the low-temperature effectiveness of Cu-zeolite catalysts. The metal oxide/Cu-zeolite composite catalysts have demonstrated superior deNOx performance at lower temperatures compared to Cu-zeolite alone. However, the hydrothermal stability of these composite catalysts remains unexplored. In this study, we focus on the Mn2O3/Cu-SSZ-39 catalyst, chosen for its exceptional activity at low temperatures. The synergy between the nitrate groups on Mn2O3 and NH4+ ions on the Brønsted acid sites of Cu-SSZ-39 enhances NOx conversion efficiency. Nonetheless, the efficiency of Mn2O3/Cu-SSZ-39 diminishes following exposure to hydrothermal conditions at various temperatures (700 °C, 750 °C, and 800 °C), with the degradation degree intensifying at higher temperatures. Characterization studies revealed that hydrothermal treatment leads to the recrystallization of Mn2O3 particles, which reduces the content of active adsorbed oxygen. This reduction impedes the formation of active bridged nitrates in the aged catalysts and disrupts the SCR pathway through the interaction between bridged nitrates and NH4+ on the composite catalysts. Despite these challenges, some adsorbed oxygen remains on the Mn2O3/Cu-SSZ-39 after aging, ensuring that the aged composite catalyst still exhibits higher activity than the fresh Cu-SSZ-39 catalyst. This observation suggests that there is potential for the application of Mn2O3/Cu-SSZ-39 in practical scenarios.

Investigation into the impact of CeO2 morphology regulation on the oxidation process of dichloromethane.

Four distinct CeO2 catalysts featuring varied morphologies (nanorods, nanocubes, nanoparticles, and nano spindle-shaped) were synthesized through a hydrothermal process and subsequently employed in the oxidation of dichloromethane (DCM). The findings revealed that the nano spindle-shaped CeO2 exhibited exposure of crystal faces (111), demonstrating superior catalytic oxidation performance for DCM with a T90 of 337 °C and notably excellent low-temperature catalytic activity (T50 = 192 °C). The primary reaction products were identified as HCl and CO2. Through obvious characterizations, it showed that the excellent catalytic activity presented by CeO2-s catalyst might be related to the higher oxygen vacancy concentration, surface active oxygen content, and superior redox performance caused by specific exposed crystal planes. Meanwhile, CeO2-s catalyst owned outstanding stability, reusability, and water inactivation regeneration, which had tremendous potential in practical treatment.

Hydrogen‑rich saline promotes neuronal recovery in mice with cerebral ischemia through the AMPK/mTOR signal‑mediated autophagy pathway.

This study explored the protective effect and mechanism of hydrogen‑rich saline (HRS) on the neurological function of mice with cerebral ischemia. Effects of HRS on neurological function in mice with cerebral ischemia were evaluated by neurological function scores. Infarct volume and histological damage were evaluated by 2,3,5‑triphenyl tetrazolium chloride staining (TTC staining). Golgi‑Cox staining was conducted to measure the morphological changes of neuronal dendrites and dendritic spines. The expression of neuronal markers was detected by immunofluorescence. Western blot was used to detect protein expression. The infarct volume of mice in the HRS‑H group decreased significantly compared to that of the distal middle cerebral artery occlusion (dMCAO) group. Mice in the HRS‑H group had a lower neurological deficit score than that in the dMCAO group. Compared to the dMCAO group, the activity of superoxide dismutase (SOD) and the level of glutathione (GSH) significantly increased in the HRS‑H group. Compared with the dMCAO group, the number of apoptotic cells in the HRS‑H group decreased. Administration of HRS was shown to be able to decrease cavitation of the brain cortex after ischemia. The spine density in the HRS‑H group increased compared to that of the dMCAO group. In the in vitro experiment, compared with the oxygen‑glucose deprivation (OGD) group, the active oxygen content in the 75% HRM group decreased, and the mitochondrial membrane potential and adenosine triphosphate (ATP) content increased. Compared with the OGD group, the ratio of P‑AMPK and the levels of LC3II/LC3I in the hydrogen‑rich medium (HRM) group was upregulated, and P‑mTOR levels and P62 levels in the HRM group were down‑regulated. HRS can enhance neuroplasticity after ischemia and promote neurological recovery in mice with cerebral ischemia, which may involve the autophagy pathway mediated by the AMPK/mTOR signaling pathway.

5-ALA Improves the Low Temperature Tolerance of Common Bean Seedlings through a Combination of Hormone Transduction Pathways and Chlorophyll Metabolism.

Low-temperature stress is a key factor limiting the yield and quality of the common bean. 5-aminolevulinic acid (5-ALA), an antioxidant in plants, has been shown to modulate plant cold stress responses. However, the molecular mechanisms of 5-ALA-induced physiological and chemical changes in common bean seedlings under cold stress remains unknown. This study explored the physiological and transcriptome changes of common bean seedlings in response to cold stress after 5-ALA pretreatment. Physiological results showed that exogenous 5-ALA promotes the growth of common bean plants under cold stress, increases the activity of antioxidant enzymes (superoxide dismutase: 23.8%; peroxidase: 10.71%; catalase: 9.09%) and proline content (24.24%), decreases the relative conductivity (23.83%), malondialdehyde (33.65%), and active oxygen content, and alleviates the damage caused by cold to common bean seedlings. Transcriptome analysis revealed that 214 differentially expressed genes (DEGs) participate in response to cold stress. The DEGs are mainly concentrated in indole alkaloid biosynthesis, carotenoid biosynthesis, porphyrin, and chlorophyll metabolism. It is evident that exogenous 5-ALA alters the expression of genes associated with porphyrin and chlorophyll metabolism, as well as the plant hormone signal transduction pathway, which helps to maintain the energy supply and metabolic homeostasis under low-temperature stress. The results reveal the effect that applying exogenous 5-ALA has on the cold tolerance of the common bean and the molecular mechanism of its response to cold tolerance, which provides a theoretical basis for exploring and improving plant tolerance to low temperatures.

Thermodynamic investigations of steel deoxidation process with calcium and barium

The use of alloys with alkaline earth metals (AEM) it possible to optimize the processes of deoxidation and refining of steel from non-metallic inclusions. The technologies of ladle treatment of the melt with the use of AEM complexes to obtain high-quality metal products even if it is impossible to use expensive equipment (vacuumers, tribe apparatus, etc.), which is often typical for small steel foundries. At the same time, a number of issues related to the mechanisms implemented during the refining of liquid steel with calcium and barium require further study. In the course of this work, the authors constructed state diagrams of double (CaO–BaO) and ternary (FeO–CaO–BaO) oxide systems and carried out thermodynamic modeling of equilibria in the Fe–Ca–Ba–C–O system. It is noted that in this system there is an extensive equilibrium region of the oxide melt with solid solutions of CaO-based oxides. The solubility surfaces of components for the temperatures of steel ladle treatment (1550–1600 °С) and for different carbon contents (0; 0,1; 0,4 % С) are constructed for the studied system. A comparative analysis of the constructed diagrams suggests that a change in the carbon content within the indicated limits does not significantly affect the type of the diagrams. It follows that the revealed patterns will be maintained in the production of a wide range of economically alloyed low-carbon steels. It is shown that during the deoxidation of steel without aluminum, and with a calcium content typical for real production processes (about 30 ppm), the expected active oxygen content is about 30 ppm (log[O] = –2.5), which does not meet modern requirements for purity become. At the same time, a change of the barium content has practically no effect on the degree of deoxidation of the metal. Thus, it is shown that the main role of calcium and, especially, barium in the processing of liquid steel is modification and removal of non-metallic inclusions from the melt

Toluene combustion over Co3O4-CNTs/PSSF catalysts and investigation of the effects of acid treatment on catalytic activity

BackgroundCo3O4 shows potential as a cost-effective alternative to precious metal catalysts for VOCs catalytic combustion. However, its catalytic activity requires further enhancement. MethodsA new type of paper-like carbon nanotube membrane composite (CNTs/PSSF) was used as a support to prepare Co3O4-CNTs/PSSF catalysts by metal-organic vapor deposition (MOCVD) and impregnation method (IM) respectively for toluene combustion. Besides, the effects of acid treatment to support on the catalytic activity were investigated. Various characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and oxygen temperature-programmed desorption (O2-TPD), were employed to evaluate the effects of different preparation methods and acid treatment on the structure and catalytic performance mechanism of Co3O4-CNTs/PSSF. Significant findingsThe preparation method significantly affects the catalyst's properties and catalytic activity. Compared with IM, the MOCVD-prepared catalysts show stronger coordination of carbon nanotubes, resulting in more oxygen vacancies and surface active oxygen. Additionally, oxygenous groups introduced by HNO3 form Co-O-C linkage between Co and CNTs, promoting oxygen vacancies and enhancing surface active oxygen content, thereby dramatically improving the catalyst's catalytic activity, especially for HIM-10 whose T90 is reduced by 140 °C. This work provides insights for enhancing the catalytic combustion activity of cobalt oxide.

Bimetallic catalysts Ag-K(Cs)/ZSM-5 for efficient soot oxidation via synergistically regulating active species and support of catalyst

Diesel soot oxidation is a typical gas (O2)-solid (soot)-solid (catalyst) three-phase oxidation, which requires both high contact efficiency between the three-phase substances and excellent intrinsic catalytic activity of catalysts. We proposed a new strategy for improving the catalytic performances of Ag/HZSM-5 catalyst for diesel soot oxidation via synergistically regulating both active species and support of catalyst. One is constructing hierarchical pore structure on HZSM-5 (denoted as Z) support by lye treatment with various concentration (0.1 M, 0.2 M and 0.5 M); the other is incorporating alkali-metal (K or Cs) into the Ag/Z catalyst to form the bimetallic catalysts. Internally, the bimetallic catalysts Ag-K/Z-0.1 M and Ag-Cs/Z-0.1 M exhibited the superior catalytic activities. The CO2 selectivity reached 98.6% and 95.6% for Ag-K/Z-0.1 M and Ag-Cs/Z-0.1 M, respectively. In addition, Ag-Cs/Z-0.1 M obtained excellent stability, maintaining almost 100% activity without any recession after 10 cycles. Moreover, both bimetallic catalysts exhibited excellent sulfur and water resistance. The physicochemical properties of the bimetallic catalyst systems were investigated by SEM, N2 adsorption–desorption, XRD, XPS, O2-TPD, etc. The linear relationship between metallic silver and active oxygen content, and their correlation with catalysts activities have been discussed. Finally, possible dual synergistic effects in the bimetallic systems have been proposed.