H2O2 Concentration Research Articles

Platinum-Particle-Assisted Etching of Low-, Moderately-, and Highly-Doped p-Type Silicon: Change of Composite Porous Structure

Metal-assisted etching (metal-assisted chemical etching) is an efficient method to fabricate porous silicon (Si). When using platinum (Pt) particles as metal catalysts in metal-assisted etching, a composite porous structure of straight macropores formed beneath the Pt particles and a mesoporous layer formed on the entire surface of Si can be fabricated. The formation mechanism of the composite structure is still open to discussion. We previously demonstrated that the ratio of mesoporous layer thickness to macropore depth showed a large value (approximately 1.1) in the case of highly-doped p-Si. In this study, we investigated the composite structure formation by using p-Si substrates with different doping densities and etching solutions with different concentrations of hydrogen peroxide (H2O2). There was not significant difference in the structures formed on low- and moderately-doped Si, despite the large difference in doping density. The ratio of mesoporous layer thickness to macropore depth increased within the range approximately from 0.1 to 0.4 with increasing the H2O2 concentration in the case of low- and moderately-doped Si, but it did not change in the case of highly-doped Si. We discussed the observation results based on the spatial distribution of hole consumption and the band structures at Pt/Si and Si/electrolyte interfaces.

A homologous membrane-camouflaged self-assembled nanodrug for synergistic antitumor therapy

Limited success has been achieved in ferroptosis-induced cancer treatment due to the challenges related to low production of toxic reactive oxygen species (ROS) and inherent ROS resistance in cancer cells. To address this issue, a self-assembled nanodrug have been investigated that enhances ferroptosis therapy by increasing ROS production and reducing ROS inhibition. The nanodrug is constructed by allowing doxorubicin (DOX) to interact with Fe2+ through coordination interactions, forming a stable DOX-Fe2+ chelate, and this chelate further interacts with sorafenib (SRF), resulting in a stable and uniform nanoparticle. In tumor cells, overexpressed glutathione (GSH) triggers the disassembly of nanodrug, thereby activating the drug release. Interestingly, the released DOX not only activates nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) to produce abundant H2O2 production for enhanced ROS production, but also acts as a chemotherapeutics agent, synergizing with ferroptosis. To enhance tumor selectivity and improve the blood clearance, the nanodrug is coated with a related cancer cell membrane, which enhances the selective inhibition of tumor growth and metastasis in a B16F10 mice model. Our findings provide valuable insights into the rational design of self-assembled nanodrug for enhanced ferroptosis therapy in cancer treatment. Statement of significanceFerroptosis is a non-apoptotic form of cell death induced by the iron-regulated lipid peroxides (LPOs), offering a promising potential for effective and safe anti-cancer treatment. However, two significant challenges hinder its clinical application: 1) The easily oxidized nature of Fe2+ and the low concentration of H2O2 leads to a low efficiency of intracellular Fenton reaction, resulting in poor therapeutic efficacy; 2) The instinctive ROS resistance of cancer cells induce drug resistance. Therefore, we developed a simple and high-efficiency nanodrug composed of self-assembling by Fe2+ sources, H2O2 inducer and ROS resistance inhibitors. This nanodrug can effectively deliver the Fe2+ sources into tumor tissue, enhance intracellular concentration of H2O2, and reduce ROS resistance, achieving a high-efficiency, precise and safe ferroptosis therapy.

Identification and Characterization of Polyamine Metabolism in Citrus in Response to 'Candidatus Liberibacter asiaticus' Infection.

Citrus Huanglongbing, one of the most devastating citrus diseases, is caused by 'Candidatus Liberibacter asiaticus' (CLas). Polyamines are aliphatic nitrogen-containing compounds that play important roles in disease resistance and are synthesized primarily by two pathways: an arginine decarboxylation pathway and an ornithine decarboxylation pathway. However, it is unclear whether polyamines play a role in the tolerance of citrus to infection by CLas and, if so, whether one or both of the core polyamine metabolic pathways are important. We used high-performance liquid chromatography and ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry to detect the contents of nine polyamine metabolism-related compounds in six citrus cultivars with varying levels of tolerance to CLas. We also systematically detected the changes in polyamine metabolism-related compounds and H2O2 contents and compared the gene expression levels and the activities of enzymes involved in the polyamine metabolic pathway among healthy, asymptomatic, and symptomatic leaves of Newhall navel oranges infected with CLas. The tolerant and moderately tolerant varieties showed higher polyamine metabolism-related compound levels than those of susceptible varieties. Compared with the healthy group, the symptomatic group showed significantly increased contents of arginine, ornithine, γ-aminobutyric acid, and putrescine by approximately 180, 19, 1.5, and 0.2 times, respectively, and upregulated expression of biosynthetic genes. Arginase and ornithine decarboxylase enzyme activities were the highest in the symptomatic group, whereas arginine decarboxylase and agmatine deiminase enzyme activities were the highest in the asymptomatic group. The two polyamine biosynthetic pathways showed different trends with the increase of the CLas titer, indicating that polyamines were mainly synthesized through the arginine decarboxylase pathway in the asymptomatic leaves and were synthesized via the ornithine decarboxylase pathway in symptomatic leaves. These findings provide new insight into the changes in polyamine metabolism in citrus infected with CLas.

Palladium nanocubes-mediated Fenton catalysis combined with chloride ion-amplified electro-driven catalysis for dye degradation

Electrochemical technology is frequently used to treat industrial dye wastewater. However, its degradation efficiency is restricted by pH, and the low current efficiency and high energy consumption limit its broader application. Based on this, we constructed an innovative electro-driven catalytic system by integrating nanotechnology with electric current. This system operates without pH constraints, has low energy consumption, and allows for the recycle and reuse of both electrodes and catalysts. Firstly, we synthesized palladium (Pd) cubes via a solvothermal method, and characterized their morphology, structural composition, and crystalline properties using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and other methods. The prepared Pd cubes possessed dual catalytic properties of electro-driven catalysis and Fenton catalysis, achieving a synergistic degradation effect under an electric field. Subsequently, the study explored how catalysts dosage, H2O2 concentration, pH and Cl− concentration affect the catalytic rate. The optimized system was able to degrade 99.17 % of MB within 1 h and was effective against various organic pollutants. After five cycles of reuse, the recovered catalysts maintained over 90 % degradation efficiency in decomposing MB. This process realizes efficient degradation with a low concentration of catalysts, offering a novel approach for nanotechnology in wastewater treatment under electro-driven conditions.

Methyl jasmonate enhances the safe production ability of Cd-stressed wheat by regulating the antioxidant capacity, Cd absorption, and distribution in wheat

Identifying green and effective measures for reducing wheat Cd toxicity and grain Cd accumulation is crucial. This study used seedling sand culture and full-grown pot experiments of wheat cultivars ‘Luomai23’ (LM) and ‘Zhongyu10’ (ZY). The purpose was to determine the effects of exogenous MeJA on the phenotype, photosynthesis, antioxidant system, Cd accumulation and distribution, transporter gene expression, and cell wall properties of Cd-stressed wheat. Compared with Cd treatment alone, the plant height and maximum root length treated with 0.001 μM MeJA increased by more than 6.3% and 16.6%, respectively. Under 5 mg⋅kg−1 Cd treatment, spraying 10 μM MeJA increased the photosynthetic rate of LM and ZY by 23.5% and 35.8% at the filling stage, respectively. Methyl jasmonate significantly reduced the H2O2 and MDA contents by increasing the activities of POD, DHAR, MDHAR, and GR and the contents of AsA and GSH. Applicating MeJA increased the content of chelate substances, cell wall polysaccharides, and cell wall functional groups. Besides, MeJA regulated the expression of Cd transporter genes, with shoot and root Cd content decreasing by 46.7% and 27.9% in LM, respectively. Spraying 10 μM MeJA reduced Cd absorption and translocation from vegetative organs to grains, thus reducing the grain Cd content of LM and ZY by 36.1 and 39.9% under 5 mg⋅kg−1 Cd treatment, respectively. Overexpressing TaJMT significantly increased the MeJA content and Cd tolerance of Arabidopsis. These results have improved the understanding of the mechanism through which MeJA alleviates Cd toxicity and reduces Cd accumulation in wheat.

Thiourea improves yield and quality traits of Brassica napus L. by upregulating the antioxidant defense system under high temperature stress

High temperature stress influences plant growth, seed yield, and fatty acid contents by causing oxidative damage. This study investigated the potential of thiourea (TU) to mitigate oxidative stress and restoring seed oil content and quality in canola. The study thoroughly examined three main factors: (i) growth conditions—control and high temperature stress (35 °C); (ii) TU supplementation (1000 mg/L)—including variations like having no TU, water application at the seedling stage, TU application at seedling stage (BBCH Scale-39), water spray at anthesis stage, and TU application at anthesis stage (BBCH Scale-60); (iii) and two canola genotypes, 45S42 and Hiola-401, were studied separately. High temperature stress reduced growth and tissue water content, as plant height and relative water contents were decreased by 26 and 36% in 45S42 and 27 and 42% Hiola-401, respectively, resulting in a substantial decrease in seed yield per plant by 36 and 38% in 45S42 and Hiola-401. Seed oil content and quality parameters were also negatively affected by high temperature stress as seed oil content was reduced by 32 and 35% in 45S42 and Hiola-401. High-temperature stress increased the plant stress indicators like malondialdehyde, H2O2 content, and electrolyte leakage; these indicators were increased in both canola genotypes as compared to control. Interestingly, TU supplementation restored plant performance, enhancing height, relative water content, foliar chlorophyll (SPAD value), and seed yield per plant by 21, 15, 30, and 28% in 45S42; 19, 13, 26, and 21% in Hiola-401, respectively, under high temperature stress as compared to control. In addition, seed quality, seed oil content, linoleic acid, and linolenic acid were improved by 16, 14, and 22% in 45S42, and 16, 11, and 23% in Hiola-401, as compared to control. The most significant improvements in canola seed yield per plant were observed when TU was applied at the anthesis stage. Additionally, the research highlighted that canola genotype 45S42 responded better to TU applications and exhibited greater resilience against high temperature stress compared to genotype Hiola-401. This interesting study revealed that TU supplementation, particularly at the anthesis stage, improved high temperature stress tolerance, seed oil content, and fatty acid profile in two canola genotypes.

Aliphatic Olefin Epoxidation with Hydrogen Peroxide Catalyzed by an Integrated Mn/TS-1/N System

AbstractPropylene liquid-phase epoxidation with 50–75% H2O2 is an important process for the industrial production of propylene oxide (PO). To realize a propylene epoxidation process that proceeds with low hydrogen peroxide concentration, we developed an integrated Mn/TS-1/N catalytic system via in-situ reaction of Mn/TS-1 with an N-donor ligand, affording the PO product in excellent yield with only 30 wt% H2O2. Other long-chain aliphatic epoxides were also readily synthesized by this catalytic epoxidation system. Moreover, in addition to the standard micro-pressure reactor, a continuous-flow microreactor was developed that executed the hydrogen peroxide propylene oxide (HPPO) process with excellent efficiency for 1300 hours. This innovative Mn/TS-1/N catalyzed epoxidation represents a promising direction for advancing HPPO industrial processes, offering improved efficiency while minimizing the reliance on high concentrations of H2O2.

Hydrogen peroxide modulates the expression of the target of rapamycin (TOR) and cell division in Arabidopsis thaliana.

Hydrogen peroxide (H2O2) is naturally produced by plant cells during normal development and serves as a messenger that regulates cell metabolism. Despite its importance, the relationship between hydrogen peroxide and the target of rapamycin (TOR) pathway, as well as its impact on cell division, has been poorly analyzed. In this study, we explore the interaction of H2O2 with TOR, a serine/threonine protein kinase that plays a central role in controlling cell growth, size, and metabolism in Arabidopsis thaliana. By applying two concentrations of H2O2 exogenously (0.5 and 1mM), we could correlate developmental traits, such as primary root growth, lateral root formation, and fresh weight, with the expression of the cell cycle gene CYCB1;1, as well as TOR expression. When assessing the expression of the ribosome biogenesis-related gene RPS27B, an increase of 94.34% was noted following exposure to 1mM H2O2 treatment. This increase was suppressed by the TOR inhibitor torin 2. The elimination of H2O2 accumulation with ascorbic acid (AA) resulted in decreased cell division as well as TOR expression. The potential molecular mechanisms associated with the effects of H2O2 on the cell cycle and TOR expression in roots are discussed in the context of the results.

Effects of Na+/H2O2 on nitrogen removal and sludge activity: Performance and mechanism

A large amount of wastewater containing Na+ and H2O2 was generated in the pharmaceutical, food and dyeing industries. After entering sewage treatment plant, they could interfere with the growth and metabolism of microorganisms. However, the effects of coexisting Na+/H2O2 on nitrogen removal and sludge flocculation were unclear. In this study, the effects of Na+/H2O2 on removal efficiencies of pollutants and sludge activity were investigated using sequencing batch reactor. The composition and structure of extracellular polymer substance (EPS) were analyzed, and the influencing mechanisms of Na+/H2O2 on the activated sludge were revealed. The results showed that when concentration ratio of Na+/H2O2 was 30, removal efficiencies of COD and TN were the highest values of 96 % and 68 %, ARE, NAR and SAOR were 56.9 %, 35.3 % and 24.08 mg N/(mg MLVSS·h), respectively. The level of oxidative stress was the lowest, and ROS and MDA were 30.78 % and 32.65 %, respectively. Zeta potential, particle size and flocculation capacity of the sludge reached the highest values of -4.1283 mV, 48.73 μm and 8.92 %, respectively. Na+ promoted the decomposition of H2O2, and ·OH, ·O2- and 1O2 produced improved denitrification rate. However, removal efficiencies of pollutants and sludge activity were decreased when Na+/H2O2 concentration ratio was higher and lower than 30. The coexisting Na+/H2O2 could promote the production of EPS and improve fluorescence intensity of protein and humic acids, but main components and functional groups of EPS were not changed. Therefore, removal efficiencies of pollutants and sludge flocculation could be improved by regulating influent concentration ratio of Na+/H2O2.

Assessing pollution degree and human health risks from hazardous element distribution in soils near gold mines in a Colombian Andean region: Correlation with phytotoxicity biomarkers

The assessment of human health risk due to the presence of hazardous elements in the environment is now necessary for environmental management and legislative initiatives. This study aims to determine the contamination by As, Cd, Pb, and Cr in soils near gold mines in three municipalities located in the Andean region of Colombia. One of the main objectives of the study is to explore possible correlations between the Lifetime Cancer Risk (LCR) and phytotoxicity biomarkers using a simple and rapid-response plant model, radish (Raphanus sativus L.). In the municipality of Yalí, Puerto Berrío, and Buriticá, the hazardous elements concentrations ranged from 8.1 to 35.5, 1.7 to 892, and 5.8 to 49.8 for As, 0.1 to 4.6, 0.1 to 65.2, and 0.5 to 18.2 for Cd, 18.5 to 201.3, 13.0 to 1908, and 189 to 2345 for Pb, and 5.4 to 118.4, 65.4 to 301, and 5.4 to 102.3 for Cr, respectively. The results showed that the biomarkers intracellular H2O2 concentration, antioxidant activity, and radicle elongation exhibited significant (P < 0.05) variations associated with the concentration of hazardous elements in the soils. Significant correlations (P < 0.05, r > 0.58) were found between the biomarkers and the LCR for Cd, Pb, and Cr, but not for As. The results using biomarkers reveal that soil pH and organic matter content are important variables that control the bioavailability of these elements in the soil. The use of indicators like LCR alone has limitations and should be accompanied by the use of biomarkers that allow for a better understanding of the biological system's response to exposure to potentially toxic elements. The results obtained show the urgent need to implement public policies to minimize exposure to hazardous substances in areas near gold mining projects.

Trans-electrode pressure of gas-diffusion electrodes significantly influencing the electrochemical hydrogen peroxide production

Hydrogen peroxide (H2O2) synthesis by electrochemical two-electron oxygen reduction has garnered increasing interest as a wide range of potential applications. Gas diffusion electrodes (GDEs) can effectively promote the H2O2 production efficiency by overcoming the oxygen mass transfer limitations but strongly influenced by the electrowetting process along the long-term operation. In this study, the effect of trans-electrode pressure (TEP) of GDE cathode on the electrowetting process was further elucidated. We controlled the TEP values of four types of GDEs: two Ni-based GDEs and two carbon cloth GDEs prepared by hot-pressing or brushing carbon black. SBA-15 was further used to regulate the microstructure of one Ni-based GDE. It was found that an optimal range of TEP occurred for all tested GDEs in terms of the max. concentration, the yield efficiency, the energy consumption, and the stability because TEP may change the triple-phase interface and influence the anti-electrowetting effect. The porosity of hot-pressed Ni GDE can maintain the TEP window and thus enhance the production of H2O2, likely via creating oxygen-containing functional groups and a bimodal pore structure on the electrode, revealed with several characterization techniques including SEM, CA, XPS, Raman spectra, CV and EIS. The porous Ni GDE presented an efficient and stable production of H2O2 for 10 cycles: yielding H2O2 at 4393.2–4602.2 mmol m−2 h−1 with current efficiencies of 94.2–98.7%. The best accumulated H2O2 concentration can reach up to 3.58 ωt% H2O2 at 10 h. The results provide an important reference for the industrial scaleup of electro-production of H2O2 with GDEs.

A life cycle assessment of the laboratory—scale oxidative liquefaction as the chemical recycling method of the end-of-life wind turbine blades

According to the latest reports, estimated values of 50,000–66 000 t of end-of-life wind turbine blades (WTB) are expected to be decommissioned in Europe in 2025–2030, posing a significant threat from the environmental and waste management perspectives. This study aims to present the preliminary Life Cycle Assessment (LCA) with sensitivity and uncertainty analysis of the lab-scale oxidative liquefaction process of the WTB, as the original method to recover the high-quality glass fibers with simultaneous production of the secondary chemicals: phenols, ketones, acids, and fatty acids, from the oxidation of the epoxy resin from the polymer matrix. The LCA is based on the experimental results of the oxidative liquefaction process carried out on a laboratory scale using a Parr 500 ml batch reactor, at two different conditions sets for the functional unit (FU) of 1 kg of treated WTB. Each of the analyzed scenarios resulted in higher impact indicators compared to the landfilling. The highest quality fibers were obtained at 350 °C and 40 wt % H2O2 content resulted in 5.52 ± 1.20 kgCO2 eq Climate change impact and 97.8 ± 20.6 MJ of Resource use, fossil per kg of recycled WTB. The lowest quality fiber recovered in char, yet well separated from the matrix obtained at 250 °C and the lowest H2O2 content resulted in 0.0953 ± 0.487 kgCO2 eq Climate change impact and 8.84 ± 7.90 MJ of Resource use, fossil per kg of recycled WTB. The hot spot and sensitivity analysis indicated, that the oxidizer for the process – hydrogen peroxide, when acquired as a shelf product causes a significant burden on the whole process, with sensitivity ratios on the total impact indicators varying across the categories from 0.56 to 0.99. Substitution of H2O2 with theoretical 0-input oxidizer allowed to significantly lower environmental load of the recycling process, which in all of the analyzed scenarios presented environmental benefits compared to landfilling with recovery of the glass fiber and secondary chemicals.

Enhanced hydrogen peroxide electrosynthesis and prolonged lifespan by preparing gas diffusion electrode via electrodeposition of CB on Ni foam

In-situ hydrogen peroxide (H2O2) production is pivotal for the effective implementation of the electro-Fenton reaction. However, challenges such as low H2O2 yields and a short electrode lifespan have hindered its application. This study introduced a novel gas diffusion electrode (GDE), the CB(E)-Ni foam(GDE), fabricated through a combination of carbon black (CB) electrodeposition and polytetrafluoroethylene (PTFE) impregnation techniques. Comprehensive physicochemical characterizations and electrochemical evaluations indicated that CB was more uniformly dispersed across the Ni foam, enhancing its electrochemical activity. When employed as a cathode, the CB(E)-Ni foam(GDE) demonstrated superior two-electron oxygen reduction reaction (2e− ORR) capabilities, marked by increased oxygen utilization and reduced energy demands, achieving a remarkable H2O2 concentration of 897.73 mg/L after 120 min. This performance significantly outpaces that of traditional GDEs. The unique structure of the CB(E)-Ni foam(GDE) not only prolonged electrode life by preventing rapid deactivation but also boosted H2O2 production and oxygen efficiency by 31.78% and 31.79%, respectively, when compared to a standard non-GDE configuration. In practical applications, the CB(E)-Ni foam(GDE) demonstrated utility by facilitating an 84.1% degradation rate of fulvic acid over 120 min within a homogeneous electro-Fenton system, highlighting its potential for environmental remediation.

The halotolerant exopolysaccharide-producing Rhizobium azibense increases the salt tolerance mechanism in Phaseolus vulgaris (L.) by improving growth, ion homeostasis, and antioxidant defensive enzymes

Globally, agricultural productivity is facing a serious problem due to soil salinity which often causes osmotic, ionic, and redox imbalances in plants. Applying halotolerant rhizobacterial inoculants having multifarious growth-regulating traits is thought to be an effective and advantageous approach to overcome salinity stress. Here, salt-tolerant (tolerating 300 mM NaCl), exopolysaccharide (EPS) producing Rhizobium azibense SR-26 (accession no. MG063740) was assessed for salt alleviation potential by inoculating Phaseolus vulgaris (L.) plants raised under varying NaCl regimes. The metabolically active cells of strain SR-26 produced a significant amount of phytohormones (indole-3-acetic acid, gibberellic acid, and cytokinin), ACC deaminase, ammonia, and siderophore under salt stress. Increasing NaCl concentration variably affected the EPS produced by SR-26. The P-solubilization activity of the SR-26 strain was positively impacted by NaCl, as demonstrated by OD shift in NaCl-treated/untreated NBRIP medium. The detrimental effect of NaCl on plants was lowered by inoculation of halotolerant strain SR-26. Following soil inoculation, R. azibense significantly (p ≤ 0.05) enhanced seed germination (10%), root (19%) shoot (23%) biomass, leaf area (18%), total chlorophyll (21%), and carotenoid content (32%) of P. vulgaris raised in soil added with 40 mM NaCl concentration. Furthermore, strain SR-26 modulated the relative leaf water content (RLWC), proline, total soluble protein (TSP), and sugar (TSS) of salt-exposed plants. Moreover, R. azibense inoculation lowered the concentrations of oxidative stress biomarkers; MDA (29%), H2O2 content (24%), electrolyte leakage (31%), membrane stability (36%) and Na+ ion uptake (28%) when applied to 40 mM NaCl-treated plants. Further, R. azibense increases the salt tolerance mechanism of P. vulgaris by upregulating the antioxidant defensive responses. Summarily, it is reasonable to propose that EPS-synthesizing halotolerant R. azibense SR-26 should be applied as the most cost-effective option for increasing the yields of legume crops specifically P. vulgaris in salinity-challenged soil systems.

BR regulates wheat root salt tolerance by maintaining ROS homeostasis.

Trace amounts of epibrassinolide (EpiBL) could partially rescue wheat root length inhibition in salt-stressed situation by scavenging ROS, and ectopic expression of TaDWF4 or TaBAK1 enhances root salt tolerance in Arabidopsis by balancing ROS level. Salt stress often leads to ion toxicity and oxidative stress, causing cell structure damage and root development inhibition in plants. While prior research indicated the involvement of exogenous brassinosteroid (BR) in plant responses to salt stress, the precise cytological role and the function of BR in wheat root development under salt stress remain elusive. Our study demonstrates that 100mM NaCl solution inhibits wheat root development, but 5nM EpiBL partially rescues root length inhibition by decreasing H2O2 content, oxygen free radical (OFR) content, along with increasing the peroxidase (POD) and catalase (CAT) activities in salt-stressed roots. The qRT-PCR experiment also shows that expression of the ROS-scavenging genes (GPX2 and CAT2) increased in roots after applying BR, especially during salt stress situation. Transcriptional analysis reveals decreased expression of BR synthesis and root meristem development genes under salt stress in wheat roots. Differential expression gene (DEG) enrichment analysis highlights the significant impact of salt stress on various biological processes, particularly "hydrogen peroxide catabolic process" and "response to oxidative stress". Additionally, the BR biosynthesis pathway is enriched under salt stress conditions. Therefore, we investigated the involvement of wheat BR synthesis gene TaDWF4 and BR signaling gene TaBAK1 in salt stress responses in roots. Our results demonstrate that ectopic expression of TaDWF4 or TaBAK1 enhances salt tolerance in Arabidopsis by balancing ROS (Reactive oxygen species) levels in roots.

Enhanced removing of cyanobacterium by NZVI coupled with H2O2: Influencing factors and removal mechanisms

AbstractAs advanced oxidation processes (AOPs) is considered to be a highly effective approach for degrading organic pollutants, the simultaneous coagulation and oxidation process by the Fenton‐like reaction of nanoscale zero‐valent iron (NZVI) and hydrogen peroxide (H2O2) is investigated to eliminate the harmful cyanobacterium Microcystis aeruginosa in this study, and the process conditions are optimized using the central composite design of response surface methodology (RSM); in addition, the removal efficiency of M. aeruginosa (in terms of chlorophyll a, Chl a) and the verifications of the antioxidant abilities, as well as extracellular organic matters (EOM) and intracellular organic matters (IOM) are investigated under the optimized conditions. Results indicate that H2O2 concentration is the key factor affecting the Chl a removal efficiency, and the maximum Chl a removal reaches 98.10% under the optimized conditions: NZVI concentration 62.82 mg L−1, H2O2 concentration 54.2 mmol L−1, pH 4.38 and rotating speed 67 rpm. The high correlation coefficient (R2 &gt; 0.80) of analysis of variance (ANOVA) demonstrates the RSM model is extremely significant and suitable for experimental results. Moreover, the total organic carbon (TOC) and fluorescent substances (soluble cyanobacteria metabolic byproducts, aromatic proteins II, humic and fulvic acid‐like compounds) for both EOM and IOM are enhanced removal. It is speculated the removal mechanisms of the Fenton‐like process of NZVI/H2O2 for cyanobacterium belongs to the combined actions of the oxidation of Fe(II)/H2O2 and the coagulation of Fe(III), which destroy the defense system and result in the removal of M. aeruginosa.

Syntheses, structures, magnetism and photocatalytic degradation of methylene blue dye of two copper complexes based on a semirigid tricarboxylate ligand

Two Cu(II)-complexes [Cu(Hcpota)(4,4′-bpy)(H2O)]n1 and [Cu(Hcpota)(1,4-bib)(H2O)]n2 based on a semirigid ligand 2-(4-carboxyphenoxy)terephthalic acid (H3cpota) were solvothermally prepared and characterized. Complexes 1 and 2 exhibit an unprecedented 2D 4-connected framework with a {44.62} topology, comprising the Cu(II) ion with square pyramidal coordination. The three-dimensional frameworks are constructed by O–H···O hydrogen bonds. Magnetization analyses were conducted and revealed that complexes 1 and 2 have ferromagnetic properties. The photodegradation of Methylene blue dye was studied based on 1 and 2 as photocatalysts. The results indicated that complexes 1 and 2 exhibited remarkable photodegradation efficiencies of 86.9 % and 97.0 % after 24 min, respectively. Furthermore, pseudo-first-order kinetics was assumed for the photocatalytic reaction with a rate constant of 0.052 and 0.109 min−1 for 1 and 2. The impact of factors, including the initial concentration of MB, catalyst dosage, pH value, H2O2 concentration, and temperature on the degradation process of MB was thoroughly examined. The complexes exhibited excellent recyclability and stability as photocatalysts. Trapping experiments and LC-MS studies revealed that the primary active species responsible for the degradation reaction are hydroxyl radicals (·OH) and holes (h+).

Unveiling UVB resilience in Oryza sativa L.: Integrative analysis of physiological, molecular and microRNA responses

Rice is the staple food for more than half of the global population. It is cultivated in over 100 countries, and is predominant in Asia, which accounts for 90 % of the world's production. As the most crucial food crop globally, rice is sensitive to both UVB radiation and climate variations. UltraViolet-B radiation (UVB) is recognised as adverse factors for photosynthesis and plant growth. The current study investigates the resilience of Oryza sativa L. (IR20) seedlings to UVB irradiation, focusing on parameters such as photosynthetic pigment, total sugar, phenolic, total free amino acids, malondialdehyde content, hydrogen peroxide, and antioxidative enzymes. The mRNA expression levels of genes involved in UVB perception, signalling, and response (UVR8, HY5, RLCK, PHT2, and URP) were studied using quantitative RT-PCR (RT-qPCR). Additionally, a computational approach was employed to identify UVB-responsive microRNAs (miRNAs) and their corresponding target mRNAs; which were subsequently validated using stem-loop RT-qPCR and RT-qPCR, respectively. Surprisingly, it was discovered that the H2O2 content in the IR20 cultivar increased in response to UVB irradiation, despite no significant changes observed in lipid peroxidation, chlorophyll, and phenolic content. Additionally, UVB irradiation increases the total sugar content and decreases the entire free amino acid content, while not affecting total protein. The RT-qPCR analysis of mRNA expression reveals that UVB exposure augment the expression of genes related to UVB signal detection (UVR8), signalling (HY5, RLCK, and WRKY), and response (PHT2, CA, and URP). Our findings also suggest that at the post-transcriptional stage, miRNAs expressed upon UVB irradiation are responsible for the significant tolerance of IR20 seedlings to UVB radiation. Overall, the results reveal that IR20 exhibits promise candidate for the development of rice varieties that are both highly productive and resilient to UVB induced stress.

Rapid and In-Field Sensing of Hydrogen Peroxide in Plant by Hydrogel Microneedle Patch.

The rapidly changing climate is exacerbating the environmental stress that negatively impacts crop health and yield. Timely sensing of plant response to stress is beneficial to timely adjust planting conditions, promoting the healthy growth of plants, and improving plant productivity. Hydrogen peroxide (H2O2) is an importantmolecule of signal transduction in plants. However, the common methods for detecting H2O2in plants are associated with certain drawbacks, such as long extraction time, cumbersome steps, dependence on large instruments, and difficulty in realizing in-field sensing. Therefore, it is urgent to establish more efficient detection methods to realize the rapid detection of H2O2 content in plants. In this research, poly (methyl vinyl ether-alt-maleic acid) (PMVE/MA) hydrogel microneedle (MN) patch for rapid extraction of leaf sap are prepared, and the extraction mechanism of PEG-crosslinked PMVE/MA hydrogel MN patch isstudied. A method of rapid detection of H2O2 content in plants based on MN patch with optical detection technology is constructed. The hydrogel MN patch can be usedfor timely H2O2 analysis. This application enables new opportunities in plant engineering, and can be extended to the safety and healthmonitoring of other plants and animals.

Cd-induced cytotoxicity and its HO-1 and ROS quenching enzyme-mediated regulation in 2–3 leaf stage seedlings of Sorghum bicolor: An important millet crop of the arid & semi-arid regions

Cadmium is a non-essential trace metal element with no known biological function. Cd is toxic to both plants and human beings; hence, it is of prime concern to the scientific community. The objective of this research is to find out the effect of heme oxygenase 1 on Cd toxicity in Sorghum bicolor seedlings. Hydroponically adapted seedlings were treated to various concentrations of Cd within the range of 10 to 200 μM. Seedlings were harvested after 120 h of Cd stress. The cellular homeostasis and metal tolerance mechanisms were conducted to evaluate growth parameters, stress parameters (MDA and H2O2 content), non-enzymatic and enzymatic parameters (CAT, APX and GPX) including HO 1. The results showed that HO 1 activity was measured to be highest in leaves at 150 μM CdCl2, which was 29.61 %.The HO 1 activity was correlated with the MDA content and antioxidant enzymes activity at this Cd concentration. The highest activity of HO 1 was revealed through the decrease of GPX and CAT activities. Consequently, HO 1 works within a cohort that helps the development of the plant's defense mechanisms by scavenging ROS, which is confirmed by the time-dependent study. Accordingly, our research highlighted that HO 1 might increase the efficiency of stress tolerance by enhancing antioxidant defence mechanisms against Cd toxicity in S. bicolor.