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We re-examined the reported increase in mitochondrial ROS production during acute hypoxia in cells. Using the Amplex Ultrared/horseradish peroxidase assay we found a decrease, not increase, in hydrogen peroxide release from HEK293 cells under acute hypoxia, at times ranging from 1 min to 3 h. The rates of superoxide/hydrogen peroxide production from each of the three major sites (site I Q in complex I and site III Qo in complex III in mitochondria, and NADH oxidases (NOX) in the cytosol) were decreased to the same extent by acute hypoxia, with no change in the cells' ability to degrade added hydrogen peroxide. A similar decrease in ROS production under acute hypoxia was found using the diacetyldichlorofluorescein assay. Using a HIF1α reporter cell line we confirmed earlier observations that suppression of superoxide production by site III Qo decreases HIF1α expression, and found similar effects of suppressing site I Q or NOX. We conclude that increased mitochondrial ROS do not drive the response of HIF1α to acute hypoxia, but suggest that cytosolic H 2 O 2 derived from site I Q , site III Qo and NOX in cells is necessary to permit HIF1α stabilization by other signals. [Display omitted] [ABSTRACT FROM AUTHOR]

The primary goals of this study were to investigate the formation of abasic sites (AP sites) induced by methyl methanesulfonate (MMS) and hydrogen peroxide (H 2 O 2), and to characterize specific types of these pro-mutagenic DNA lesions in calf thymus DNA (CT-DNA), and BEAS-2B human lung normal cell line. Furthermore, these profiles were compared with those observed in leukocytes derived from healthy controls (HC), breast cancer patients (BCP) before treatment, and 5-year survivors. Results indicated that both H 2 O 2 and MMS induced the concentration- and time-dependent formation of AP sites in CT-DNA. To characterize the specific types of AP sites induced by H 2 O 2 or MMS, we performed AP site cleavage assay using putrescine, T7 exonuclease (T7 Exo), and exonuclease III (Exo III). Results showed that the AP sites induced by H 2 O 2 in CT-DNA were predominantly 5'-and 3'-nicked AP sites and no intact AP sites were detected. By contrast, the majority of AP sites generated by MMS in CT-DNA are not excisable and are classified as residual and intact AP sites. Similar approaches were performed in human BEAS-2B cells and comparable observations were confirmed in the cell-based model. Further investigation indicated that the profile of the AP sites observed in Taiwanese HC is identical to that of BEAS-2B cells treated with H 2 O 2 whereas the pattern of AP sites detected in BCP is similar to that of CT-DNA exposed to H 2 O 2 , suggesting that these AP sites were produced primarily through reactive oxygen species (ROS) generation. More than 70 % of the AP sites in leukocytes derived from BCP were 5'-nicked and residual AP sites. Furthermore, the characteristics of the AP sites detected in 5-year survivors are comparable with the ones in HC by using putrescine cleavage assay. Overall, we speculate that deficiency in the DNA repair cascade may play a role in mediating the formation of specific types of AP sites detected in BCP. [Display omitted] • H 2 O 2 predominantly induces 5'-cleaved AP sites. • MMS predominantly induces non-excisable AP sites. • The profile of AP sites in leukocytes of healthy controls is similar to that of BEAS-2B cells treated with H 2 O 2. • The profile of AP sites in leukocytes of breast cancer patients is similar to that of CT-DNA exposed to H 2 O 2. • The predominant AP sites in human leukocytes are derived from oxidative stress primarily through the generation of ROS. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae (S. pneumoniae) is a major cause of community-acquired pneumonia. Current standard clinical therapies mainly focus on combating S. pneumoniae through antibiotics. However, the limited delivery of antibiotics and the undetoxified hydrogen peroxide (H 2 O 2) virulence factor secreted by S. pneumoniae impede the therapeutic outcomes. Here we report an inhalable catalase (CAT)-tannic acid (TA) nanoassembly for local antibiotic (levofloxacin) delivery and simultaneously neutralizing the secreted H 2 O 2 virulence factors to treat pneumococcal pneumonia. After aerosol inhalation, the inhalable formulation (denoted as CT@LVX) effectively accumulates in lung tissues through TA-mediated mucoadhesion. CAT can reduce alveolar epithelial cells apoptosis by catalyzing the decomposition of accumulated H 2 O 2 in the infected lung tissues. In synergy with antibiotic LVX-mediated S. pneumoniae elimination, CT@LVX significantly decreases lung injury companied with reduced inflammatory, resulting in 100 % survival of mice with pneumonia. In a clinically isolated S. pneumoniae strain-induced pneumonia mouse model, CT@LVX also shows superior outcomes compared to the traditional antibiotic treatment, highlighting its potential clinical application prospects. An inhalable LVX-loaded CAT-tannic acid (TA) nanoassembly (denoted as CT@LVX) was designed for the treatment of pneumococcal pneumonia, aiming neutralizing H 2 O 2 virulence factors and effectively delivering antibiotics. This nanoassembly has demonstrated strong tissue retention and protection capabilities, showing significant therapeutic potential in both standard and clinically isolated Streptococcus pneumoniae -induced pneumonia mouse models. [Display omitted] • An inhalable levofloxacin (LVX)-loaded catalase (CAT)-tannic acid (TA) nanoassembly (denoted as CT@LVX) was developed. • The inhalable CT@LVX formulation effectively accumulates in lung tissues via TA-mediated mucoadhesion. • CAT efficiently catalyzes H 2 O 2 secreted by Streptococcus pneumoniae , reducing alveolar epithelial cell apoptosis. • Combination of CAT neutralizing H 2 O 2 and LVX eliminating bacteria offers a promising treatment for pneumococcal pneumonia. [ABSTRACT FROM AUTHOR]

This study presents a new dual-mode propulsion system that utilizes an electrically pumped hydrogen peroxide and kerosene supply system, specifically designed for advanced spacecraft orbit and attitude control. The system incorporates two distinct electric pumps, one for hydrogen peroxide and another for kerosene, each engineered to optimize the propellant feed for the orbit control and attitude control engines. This configuration enables precise propellant management and thrust control, which are critical for the stringent demands of modern space missions. The dual-mode capability of the propulsion system allows for the use of hydrogen peroxide both as a monopropellant in the attitude control engine and as an oxidizer in combination with kerosene in the orbit control engine. This approach simplifies the propulsion architecture while maximizing the efficiency and utility of hydrogen peroxide as a propellant. The electric pumps are essential in providing high-pressure propellant delivery, which is necessary to achieve the desired combustion characteristics and thrust parameters. Performance evaluations of the propulsion system demonstrated significant results. The orbit control engine achieved a combustion chamber pressure of 5.9 MPa and a combustion efficiency of 98.42 %. The attitude control engine, operating at a peak pressure of 4.9 MPa, exhibited a stable pulsative mode, maintaining consistent pressure levels throughout its operational cycle. These performance metrics highlight the effectiveness of the electric pump technology in enhancing propulsion system responsiveness and efficiency. This propulsion system is expected to improve spacecraft maneuverability and reduce operational costs, making it suitable for long-duration space missions. • A versatile dual-mode space propulsion system with electric pump-fed technology. • Advanced electric pumps enable adjustable thrust and precise control. • Confirmed system feasibility and performance through successful ground tests. • Achieved high efficiency and specific impulse in propulsion engines. • Utilized hydrogen peroxide for eco-friendly, non-toxic propulsion. [ABSTRACT FROM AUTHOR]

• Contracting skeletal muscles generate reactive oxygen species (ROS) from several locations with the cell. • Although numerous ROS exist, hydrogen peroxide is recognized as a key ROS player in redox control of biological signaling. • Contraction-induced ROS production triggers signaling pathways regulating mitochondrial biogenesis and the expression of numerous genes expressing mitochondrial proteins and antioxidant enzymes. • Growing data indicate that exercise-induced ROS production is essential to achieve the full benefit of exercise-induced adaptation in skeletal muscles. The discovery that contracting skeletal muscle generates reactive oxygen species (ROS) was first reported over 40 years ago. The prevailing view in the 1980s was that exercise-induced ROS production promotes oxidation of proteins and lipids resulting in muscle damage. However, a paradigm shift occurred in the 1990s as growing research revealed that ROS are signaling molecules, capable of activating transcriptional activators/coactivators and promoting exercise-induced muscle adaptation. Growing evidence supports the notion that reduction-oxidation (redox) signaling pathways play an important role in the muscle remodeling that occurs in response to endurance exercise training. This review examines the specific role that redox signaling plays in this endurance exercise-induced skeletal muscle adaptation. We begin with a discussion of the primary sites of ROS production in contracting muscle fibers followed by a summary of the antioxidant enzymes involved in the regulation of ROS levels in the cell. We then discuss which redox-sensitive signaling pathways promote endurance exercise-induced muscle adaptation and debate the strength of the evidence supporting the notion that redox signaling plays an essential role in muscle adaptation to endurance exercise training. In hopes of stimulating future research, we highlight several important unanswered questions in this field. [Display omitted] [ABSTRACT FROM AUTHOR]

The basis of most neurological syndromes is the accumulation of free radical molecules. Quercetin is a polyphenolic bioflavonoid molecule and it has a very strong antioxidant effect by maintaining oxidative balance. There are many difficulties in the clinical use of quercetin due to its hydrophobic structure, low solubility, instability, poor oral bioavailability, and limited tissue-barrier penetration. Its synergistic use in complex with gold nanoparticles (AuNPs) could overcome these problems. AuNPs have recently emerged as an attractive candidate for delivery applications of various biomolecules and drugs. The aim of this study was to synthesize two different sized gold nanoparticles (AuNP 20 and AuNP 50) modified with polyethyleneimine (PEI) and quercetin, evaluate their potential neuroprotective effects on the in vitro oxidative stress model using DRG primary sensory neurons. It was shown that the antioxidant and anti-apoptotic ability of the bioflavonoid was preserved after exposure to the designed quercetin modified AuNPs. The PEI surface coating increased the stability and biocompatibility of the AuNPs in both sizes. It also potentially enables additional surface functionalization. This study indicates that designed nanoparticles (AuNP-Q-PEI) with different sizes could be a useful potential platform for the treatment of neurodegenerative syndromes or cancer diseases. Quercetin/PEI modified and two different sized (AuNP 20 and AuNP 50) gold nanoparticles were successfully synthesized. Designed nanoplatform (AuNPs-Q-PEI) increased stability and biocompatibility. After nanomaterial exposure in the oxidative stress model of the DRG sensory neurons, the level of ROS and apoptosis was significantly reduced. [Display omitted] • Quercetin/PEI modified and two different sized (AuNP 20 and AuNP 50) gold nanoparticles were successfully synthesized. • The antioxidant property of the bioflavonoid was preserved after exposure to designed Q-coated AuNPs in the DRG neurons. • The PEI surface coating increased the stability and biocompatibility of the AuNPs in both sizes. • The designed gold nanoconjugates could be a useful potential nanoplatform for the treatment of neurodegenerative syndromes. [ABSTRACT FROM AUTHOR]

Melanin plays an important role in protecting skin cells from harmful UV radiation, but its uneven pigmentation in the skin sometimes demands cosmetic resolution. As a safe and effective way of evening the skin tone, enzymatic decolorization of melanin at the stratum corneum has been proposed. In this regard, the use of lignin peroxidase, in the presence of hydrogen peroxide and veratryl alcohol, an electron mediator, has been explored. Here, we first show that versatile peroxidase (VP) and aryl alcohol oxidase (AAO) purified from the Pleurotus eryngii liquid culture can be used to decolorize melanin without exogenous hydrogen peroxide. This resembles the oxidative degradation pathway of lignin in nature; AAO generates hydrogen peroxide from veratryl alcohol, and VP utilizes generated hydrogen peroxide while using veratryl alcohol as a mediator. We further explored the use of POX_Pe, the crude peroxidase preparation of the Pleurotus eryngii liquid culture, for melanin decolorization because of its better stability. Using POX_Pe and veratryl alcohol, over 60 % of melanin decolorization was obtained in 1 h in the absence of exogenous hydrogen peroxide addition. Furthermore, POX_Pe could decolorize melanin in a 3D human pigmented epidermis model, demonstrating its possible applications in cosmetics. [Display omitted] • Enzymatic decolorization of the skin pigment, melanin, is drawing great attention. • Lignin degrading pathway of Pleurotus eryngii was re-purposed to decolorize melanin. • The system consists of versatile peroxidase and aryl alcohol oxidase. • The crude preparation of the enzymes showed benefits over purified enzymes. • High degree of melanin decolorization in the absence of toxic H 2 O 2 is described. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning model could predict methane yield of pretreated LW accurately. • Digestion time, pretreatment agent and pretreatment agent were crucial factors. • NaOH, KOH and AHP pretreatments were suitable for LW with low lignin content. • LW with high lignin content preferred AHP pretreatment. Chemical pretreatment is a common method to enhance the cumulative methane yield (CMY) of lignocellulosic waste (LW) but its effectiveness is subject to various factors, and accurate estimation of methane production of pretreated LW remains a challenge. Here, based on 254 LW samples, a machine learning (ML) model to predict the methane production performance of pretreated feedstock was constructed using two automated ML platforms (tree-based pipeline optimization tool and neural network intelligence). Furthermore, the interactive effects of pretreatment conditions, feedstock properties, and digestion conditions on methane production of pretreated LW were studied through model interpretability analysis. The optimal ML model performed well on the validation set, and the digestion time, pretreatment agent, and lignin content (LC) were found to be key factors affecting the methane production of pretreated LW. If the LC in the raw LW was lower than 15%, the maximum CMY might be achieved using the NaOH, KOH, and alkaline hydrogen peroxide (AHP) with concentrations of 3.8%, 4.4%, and 4.5%, respectively. On the other hand, if LC was higher than 15%, only high concentrations of AHP exceeding 4% could significantly increase methane production. This study provides valuable guidance for optimizing pretreatment process, comparing different chemical pretreatment approaches, and regulating the operation of large-scale biogas plants. [ABSTRACT FROM AUTHOR]

Hydrazine's carcinogenic and toxic nature makes its use in space propulsion expensive and necessitates careful launch campaign planning, which may cause delays. One already established alternative is to use energetic salt-based ionic solution propellants. However, the costs remain high because these salts are costly and highly regulated energetic materials. Additionally, propellants based on these energetic salts produce much higher temperatures during decomposition and combustion, as is the case for hydrazine. Consequently, expensive refractory metal-based alloys and high-temperature oxidation-resistant catalytic reactors must be used, which further drives up the costs. Alternatively, hydrogen peroxide may be used, though only in applications with a low specific impulse requirement. This study explores an alternative approach: using nitromethane, a commonly available laboratory solvent. NMP-001 is a nitromethane-based monopropellant that contains additives that allow for low-pressure combustion and reduce sensitivity to mechanical stimuli. Multiple combustion chamber configurations with varying characteristic lengths were tested in rocket combustion experiments. With the 11.5 m L ∗ -configuration, a 15.1 bar low-pressure limit could be determined. The 7.3 and 5.0 m L ∗ -configurations yielded a 16.2 and 28.3 bar low-pressure combustion limits, respectively. These outcomes are significantly below the 30 bar limit reported in the literature. Despite using only a simple heat-sink combustion chamber with a non-sophisticated injector element and a non-optimized propellant formulation, combustion was 83 to 95 % efficient with a C* ranged between 1133 to 1302 m/s. These figures are higher than for hydrogen peroxide and are comparable to the theoretical performance of state-of-the-art green liquid monopropellants. • Existing alternative ionic propellants are costly and highly regulated due to their instability and energetic properties. • Nitromethane offers a cost-effective solution with comparable performance, leading to the development of NMP-001, a nitromethane-based monopropellant with reduced sensitivity to mechanical stimuli. • Tests showed a lower low-pressure combustion limit of 15 ba. This is significantly lower than the limits reported in the literature. • The measured C*-performance for NMP-001 is better than hydrazine and comparable to LMP-103S. [ABSTRACT FROM AUTHOR]

The synergy between chemodynamic therapy (CDT) and photothermal therapy (PTT) offers a promising antimicrobial strategy for periodontitis, yet faces challenges like complex material structure and limited NIR-I light penetration. Additionally, low endogenous H 2 O 2 levels in biofilm and a focus on bacterial eradication over colonization prevention limit current treatments. To address these issues, we newly introduce a single-material system (Cu 3 P@PAH@Lox) that integrates dual functionalities to synergistically enhance antimicrobial effects and significantly reduce pathogen co-aggregation. This system utilizes PTT to increase local temperature, boosting •OH production in CDT while downregulating heat shock proteins to enhance PTT efficacy, forming a self-reinforcing feedback loop. Lactate oxidase (Lox) is employed to convert lactate—a metabolite in periodontal biofilm—into H 2 O 2 , further amplifying CDT's potential. In vitro Cu 3 P@PAH@Lox demonstrates a remarkable synergistic effect against dual-species biofilms by more than 2-log reduction of colony-forming unit. Moreover, Cu 3 P@PAH@Lox exhibits outstanding synergistic antibacterial performances to alleviate inflammation and destruction of tissue in vivo periodontitis model. Furthermore, the mechanism of pathogen co-aggregation disruption by PTT is verified via the Cbe-Ltp1-Ptk1-fimA signaling pathway. This single-material multimodal system we have herein demonstrated for the first time marks a significant advancement in periodontitis treatment, eradicating microbes and preventing bacterial colonization, offering a path to comprehensive periodontal care. The synergy between chemodynamic therapy (CDT) and photothermal therapy (PTT) has been considered a promising therapy for periodontitis. Yet, facing challenges, the complex material structure, limited NIR-I light penetration, low endogenous H 2 O 2 level in biofilm, and a focus on bacterial eradication over colonization prevention are still insufficient. This study pioneers a unique, single-material system (Cu 3 P@PAH@Lox) that synergistically enhances antimicrobial effects and substantially curtails pathogen co-aggregation, advancing periodontitis therapy. By exploiting PTT to elevate local temperatures, thereby increasing hydroxyl radical production in CDT and concurrently suppressing heat shock proteins, the system establishes a potent, self-enhancing loop. Furthermore, lactate oxidase is innovatively utilized to convert lactate from periodontal biofilm into hydrogen peroxide, augmenting the efficacy of CDT. The introduction of Cu 3 P@PAH@Lox is poised to revolutionize periodontitis treatment, eliminating microbes and impeding bacterial colonization, thereby charting a course for comprehensive periodontal management. [Display omitted] [ABSTRACT FROM AUTHOR]

This study focuses on the development a green synthesis of epoxy fatty acids (EFAs) which are commonly used as the plasticizer in polymer industries. The intracellular lipases of Candida catenulata cells as a whole-cell biocatalyst (WCB) were examined in the bio-epoxidation of free fatty acids (FFAs) with hydrogen peroxide. The FFAs in soybean soap stock, an industrial by-product of vegetable oil factories, was used as the feedstock of the process. To remove phosphates from soap stock a degumming process was tested before the bio-epoxidation reaction and results revealed that the EFAs yield was improved using the degummed fatty acids (DFAs). The attachments of magnetic Fe 3 O 4 nanoparticles to the surface of WCBs facilitated the recovery of the biocatalyst, and were improved stabilities. The activation energy for the magnetic whole-cell biocatalysts (MWCB) was 48.54 kJ mol−1, which was lower than the WCB system (51.28 kJ mol−1). The EFA yield was about 47.1 % and 33.8 % after 3 h for the MWCBs and 2 h for the WCBs, respectively. The MWCBs displayed acceptable reusability in the repetitious bio-epoxidation reaction with maintaining 59 % of the original activity after 5 cycles whereas the performance of the WCBs was 5.9 % at the same conditions. The effects of influential factors such as reaction time, molar ratio of H 2 O 2 to C C, and batch and semi-batch operations were investigated for both biocatalyst systems. The quality of EFAs was characterized by FTIR and GC-MS analyses. • A novel intracellular lipase of C. catenulata were introduced for epoxidation of free fatty acids. • A oil refinery waste after pretreatment was used as the feedstock of epoxy fatty acid production. • Magnetic whole-cell biocatalyst was developed by loading of Fe 3 O 4 nanoparticles on cell-surface. • The presence of water, organic solvent, and different molar ratios of H 2 O 2 /C C were examined. • The bare whole cells and magnetic whole cells were examined in batch and semi-batch experiments. [ABSTRACT FROM AUTHOR]

• A novel side-aerated reactor for in-situ H 2 O 2 electrosynthesis was designed. • Side-aerated reactor coupled with a composite cathode greatly improved H 2 O 2 production. • Different aeration system and cathodes were evaluated for comparison. • Key factors for in-situ H 2 O 2 electrosynthesis were determined. The active graphite felt (GF) catalytic layer was effectively synthesized through a wet ultrasonic impregnation-calcination method, modified with CB and PTFE, and implemented in a pioneering side-aeration electrochemical in-situ H 2 O 2 reactor. The optimal mass ratio (CB: PTFE 1:4) for the modified cathode catalytic layer was determined using a single-factor method. Operating under optimum conditions of initial pH 5, 0.5 L/min air flow, and a current density of 9 mA/cm2, the system achieved a remarkable maximum H 2 O 2 accumulation of 560 mg/L, with the H 2 O 2 production capacity consistently exceeding 95 % over 6 usage cycles. The refined mesoporous structure and improved three-phase interface notably amplified oxygen transfer, utilization, and H 2 O 2 yield. Side aeration led to an oxygen concentration near the cathode reaching 20 mg/L, representing a five-fold increase compared to the 3.95 mg/L achieved with conventional bottom aeration. In the final application, the reaction system exhibited efficacy in the degradation of landfill leachate concentrate. After a 60-minute reaction, complete removal of chroma was attained, and the TOC degradation rate surpassed 60 %, marking a sixfold improvement over the conventional system. These results underscore the substantial potential of the system in H 2 O 2 synthesis and environmental remediation. [ABSTRACT FROM AUTHOR]

Hypoxic tumor microenvironments pose a significant challenge in cancer treatment. Hypoxia-activated prodrugs like evofosfamide aim to specifically target and eliminate these resistant cells. However, their effectiveness is often limited by reoxygenation after cell death. We hypothesized that ascorbate's pro-oxidant properties could be harnessed to induce transient hypoxia, enhancing the efficacy of evofosfamide by overcoming reoxygenation. To test this hypothesis, we investigated the sensitivity of MIA Paca-2 and A549 cancer cells to ascorbate in vitro and in vivo. Ascorbate induced a cytotoxic effect at 5 mM that could be alleviated by endogenous administration of catalase, suggesting a role for hydrogen peroxide in its cytotoxic mechanism. In vitro, Seahorse experiments indicated that the generation of hydrogen peroxide consumes oxygen, which is offset at later time points by a reduction in oxygen consumption due to hydrogen peroxide's cytotoxic effect. In vivo, photoacoustic imaging showed pharmacologic ascorbate treatment at sublethal levels triggered a complex, multi-phasic response in tumor oxygenation across both cell lines. Initially, ascorbate generated transient hypoxia within minutes through hydrogen peroxide production, via reactions that consume oxygen. This initial hypoxic phase peaked at around 150 s and then gradually subsided. However, at longer time scales (approximately 300 s) a vasodilation effect triggered by ascorbate resulted in increased blood flow and subsequent reoxygenation. Combining sublethal levels of i. p. Ascorbate with evofosfamide significantly prolonged tumor doubling time in MIA Paca-2 and A549 xenografts compared to either treatment alone. This improvement, however, was only observed in a subpopulation of tumors, highlighting the complexity of the oxygenation response. [Display omitted] • Hypoxia targeting drugs like evofosfamide target tumors resistant to radiation and other treatments. • Transiently increasing hypoxia can increase the effectiveness of hypoxia targeting drugs. • Hydrogen peroxide production from ascorbate transiently consumes oxygen. • At longer time scales, ascorbate causes vasodilation reversing the temporary hypoxia. • Ascorbate with evofosfamide significantly slowed tumor growth compared to either treatment alone. [ABSTRACT FROM AUTHOR]

Unveiling the dynamic active site of defective carbon-based electrocatalysts for hydrogen peroxide production. [Display omitted] Defective carbon materials have emerged as promising candidates for the electrocatalysis of oxygen reduction reaction (ORR) to selectively produce H 2 O 2. However, distinguishing the roles of oxygenates and carbon defects in carbon for 2e- ORR remains to be challenging. In a recent issue of Nature Communications, Yao and coworkers pinpointed the major active sites in oxygenated carbon materials and identified the key intermediate employing a series of dynamic and simulation techniques. In addition to highlight the proposed work, this comment article also discussed pioneering methodologies to characterize structure dynamics and probe the integral active center for rational design of carbon based catalysts with atomic precision. [ABSTRACT FROM AUTHOR]

High Test Peroxide (HTP) is a well-known green and energetic material, widely used in propulsion systems in a variety of applications, including hypergolic systems. This experimental work mixed fumed silica with liquid HTP to synthesize Gelled HTP (GHTP). A high-speed camera and a time-resolved infrared camera were employed to analyze liquid/gel phase mixing, ignition, and flame spread through drop tests, adopting a promising low toxicity liquid fuel as a GHTP hypergolic pair. Liquid/gel impinging jets in ambient air were also performed, simulating a basic element of a hybrid liquid/gel propulsion system. Prior to ignition, GHTP revealed a lower mixing ratio compared to HTP, which ultimately led to an ignition delay time of 20.6 ±6.4 ms, while HTP reached 14.6 ±3.7 ms when 1 wt% of catalyst was used. The flame area, used as a parameter to quantify gas-phase reaction, also showed sensitivity to liquid/gel phase mixing. Using a less concentrated HTP solution, ignition of GHTP/liquid fuel seemed to occur around 6 s faster than liquid HTP/liquid fuel in impinging jets, probably due to differences in propellant residence time and the vapor formation process. A theoretical performance analysis considering GHTP as an oxidizer in a hybrid liquid/gel hypergolic system revealed that the gelled propellant, made with the addition of 6 wt% of fumed silica, can achieve 96% of liquid HTP's specific impulse with the selected fuel. Furthermore, the theoretical density specific impulse of the hybrid gel/liquid system would significantly surpass that of the liquid/liquid system if 10 wt% of aluminum were mixed with GHTP. To take advantage of the hybrid system, a new propulsion system composed of pistons coupled to propellant tanks is proposed to properly infuse the gelled and liquid propellants. The results from this experimental work, together with theoretical analysis, suggest that the hybrid liquid/gel system may be suitable for military applications. [Display omitted] • Use of gelled hydrogen peroxide as oxidizer in hypergolic propulsion systems. • Drop and impinging jets test reveals vapor and ignition delay times with green fuel. • Analysis before and after ignition using visible and infrared high-speed cameras. • Infrared data quantifies mixing prior to ignition and flame spread. • Gelled hydrogen peroxide may ignite faster than its liquid counterpart. [ABSTRACT FROM AUTHOR]

The purpose of this investigation is to compare Cutibacterium acnes diagnosis using culturing vs. genomic DNA sequencing (NextGen) at various timepoints and locations during primary total shoulder arthroplasty. Additionally, we intend to compare the effects of hydrogen peroxide on standard culture technique results with genomic DNA sequencing. A prospective diagnostic study of 40 patients undergoing primary total shoulder arthroplasty was performed. Intraoperatively, 4 tissue samples were collected per patient: subdermal skin edge following initial skin incision, subdermal skin edge following hydrogen peroxide soak for 5 minutes, glenohumeral joint capsule, and subdermal skin edge prior to wound closure. Each tissue specimen was collected twice (one for culture analysis and the other for genomic (NextGen) DNA sequencing analysis) for a total of 8 specimens per patient and 320 tissue specimens in total. All anaerobic cultures were held for 14 days. Each culture plate was divided into quadrants and the amount of growth was quantified. Tissue samples were collected for genomic sequencing DNA analysis. Genomic sequencing results provided relative percentage of bacteria for each specimen detected. There were 18/40 males (45%) and no postoperative complications. Average age was 72.2 ± 11.8. Overall, 18% (29/160) of standard anaerobic cultures were positive for C. Acnes and 26% (942/160) were positive with genomic (Nextgen) DNA sequencing. When comparing the NextGen results with anaerobic standard cultures, there was a calculated negative predictive value of 85.6% and positive predictive value of 28.6%. Sensitivity of the NextGen was 41.4% and specificity was 77.1%. Bacterial culture rates did not significantly change from the beginning to the end of surgery as demonstrated on standard culturing and the NextGen analysis (P >.05). After treatment with hydrogen peroxide, the standard culturing technique showed no significant difference between the samples; however, there was a significant increase in bacterial burden (12.4%) noted with NextGen analysis (P =.0147). NextGen culturing is a novel technique to help identify shoulder prosthetic joint infections. These results show that, NextGen is better at identifying the absence of infection, but has a high false positive rate indicative of its ability to identify contaminants as compared to standard anaerobic culturing methods. The increase in bacterial burden after peroxide treatment noted with NextGen could also be secondary to the test's increased ability to identify both living and dead bacterial pathogens. [ABSTRACT FROM AUTHOR]

Shoulder periprosthetic joint infection is most commonly caused by Cutibacterium. Effective removal of these bacteria from the skin is difficult because Cutibacterium live protected in the dermal sebaceous glands beneath the skin surface to which surgical preparation solutions, such as chlorhexidine gluconate (CHG), are applied. There is conflicting evidence on the additional benefit of using hydrogen peroxide (H2O2) as an adjunct to CHG in eliminating Cutibacterium from the skin. A previous study demonstrated that after CHG skin preparation, repopulation of Cutibacterium from sebaceous glands onto the skin surface occurs in 90% of shoulders by 60 minutes after application. The objective of this randomized controlled study was to determine the effectiveness of adding H2O2 to CHG in reducing skin Cutibacterium. Eighteen male volunteers (36 shoulders) were recruited for this study. The 2 shoulders of each volunteer were randomized to receive the control preparation ("CHG-only" – 2% CHG in 70% isopropyl alcohol alone) or the study preparation ("H2O2+CHG" – 3% H2O2 followed by 2% CHG in 70% isopropyl alcohol). Skin swabs were taken from each shoulder prior to skin preparation and again at 60 minutes after preparation. Swabs were cultured for Cutibacterium and observed for 14 days. Cutibacterium skin load was reported using a semiquantitative system based on the number of quadrants growing on the culture plate. Prior to skin preparation, 100% of the CHG-only shoulders and 100% of the H2O2+CHG shoulders had positive skin surface cultures for Cutibacterium. Repopulation of Cutibacterium on the skin at 60 minutes occurred in 78% of CHG-only and 78% of H2O2+CHG shoulders (P = 1.00). Reduction of Cutibacterium skin levels occurred in 56% of CHG-only and 61% of H2O2+CHG shoulders (P =.735). Cutibacterium levels were significantly decreased from before skin preparation to 60 minutes after preparation in both the CHG-only (2.1 ± 0.8 to 1.3 ± 0.9, P =.003) and the H2O2+CHG groups (2.2 ± 0.7 to 1.4 ± 0.9, P <.001). Substantial skin surface levels of Cutibacterium were present at 60 minutes after both preparations. In this randomized controlled study, there was no additional benefit of using hydrogen peroxide as an adjunct to chlorhexidine gluconate skin preparation in the reduction of cutaneous Cutibacterium levels. Neither preparation was able to eliminate repopulation of Cutibacterium on the skin surface from the dermal sebaceous glands. [ABSTRACT FROM AUTHOR]

• An updated review on ROS implicated in AOPs for pharmaceutical waste is presented. • Potential ROS are implicated in the pharmaceutical waste degradation. • Mechanistic insights regarding ROS-mediated reaction pathways are discussed. • The main detected transformation products of ACT using specific ROS are reported. Innately designed to induce physiological changes, pharmaceuticals are foreknowingly hazardous to the ecosystem. Advanced oxidation processes (AOPs) are recognized as a set of contemporary and highly efficient methods being used as a contrivance for the removal of pharmaceutical residues. Since reactive oxygen species (ROS) are formed in these processes to interact and contribute directly toward the oxidation of target contaminant(s), a profound insight regarding the mechanisms of ROS leading to the degradation of pharmaceuticals is fundamentally significant. The conceptualization of some specific reaction mechanisms allows the design of an effective and safe degradation process that can empirically reduce the environmental impact of the micropollutants. This review mainly deliberates the mechanistic reaction pathways for ROS-mediated degradation of pharmaceuticals often leading to complete mineralization, with a focus on acetaminophen as a drug waste model. [ABSTRACT FROM AUTHOR]

The complex interplay between hydrogen peroxide (H 2 O 2) and nitric oxide (NO) in endothelial cells presents challenges due to technical limitations in simultaneous measurement, hindering the elucidation of their direct relationship. Previous studies have yielded conflicting findings regarding the impact of H 2 O 2 on NO production. To address this problem, we employed genetically encoded biosensors, HyPer7 for H 2 O 2 and geNOps for NO, allowing simultaneous imaging in single endothelial cells. Optimization strategies were implemented to enhance biosensor performance, including camera binning, temperature regulation, and environmental adjustments to mimic physiological normoxia. Our results demonstrate that under ambient oxygen conditions, H 2 O 2 exhibited no significant influence on NO production. Subsequent exploration under physiological normoxia (5 kPa O 2) revealed distinct oxidative stress levels characterized by reduced basal HyPer7 signals, enhanced H 2 O 2 scavenging kinetics, and altered responses to pharmacological treatment. Investigation of the relationship between H 2 O 2 and NO under varying oxygen conditions revealed a lack of NO response to H 2 O 2 under hyperoxia (18 kPa O 2) but a modest NO response under physiological normoxia (5 kPa O 2). Importantly, the NO response was attenuated by l -NAME, suggesting activation of eNOS by endogenous H 2 O 2 generation upon auranofin treatment. Our study highlights the intricate interplay between H 2 O 2 and NO within the endothelial EA.hy926 cell line, emphasizing the necessity for additional research within physiological contexts due to differential response observed under physiological normoxia (5 kPa O 2). This further investigation is essential for a comprehensive understanding of the H 2 O 2 and NO signaling considering the physiological effects of ambient O 2 levels involved. [Display omitted] • Co-expressing HyPer7 and O-geNOps enable multichromatic imaging of H 2 O 2 and NO in endothelial cells. • Exogenous H 2 O 2 does not affect NO levels under hyperoxic and normoxic conditions. • Endogenous H 2 O 2 generation has minimal NO impact under normoxic conditions. [ABSTRACT FROM AUTHOR]

Solar-driven hydrogen (H 2) and hydrogen peroxide (H 2 O 2) generation over visible-light responsive carbon nitride (CN) photocatalysts for in situ efficient sterilization is a promising and eco-friendly strategy. Herein, a colloidal potassium-ion (K+) intercalated crystalline CN nanosheets (KCCN) photocatalyst was constructed for boosting synergetic H 2 O 2 synthesis with isopropanol (IPA) oxidation and in situ antibacterial effect. The surface hydroxyl (−OH) and cyano (−C N) groups induced by molten salt (KCl)-assisted thermal treatments contributed to the colloidal nature of CN, facilitating for high wettability of KCCN in aqueous solution to gain active hydrogen (H+) from water sustainably. Meaningfully, the enhanced high-energy singlet oxygen species (1O 2) produced by KCNN-2 were verified by electron paramagnetic resonance (EPR) and 9,10-anthracenediyl-bis(methylene)-dimalonic acid (ABDA)-fluorescent probe, significantly contributing to H 2 O 2 production and antibacterial effect. Consequently, the optimal KCCN-2 exhibited a much enhanced H 2 generation of 4.11 mmol g−1 h−1, and H 2 O 2 production activity of 1.82 mmol L−1 h−1 with acetone yield rate of 47.3 mmol g−1 h−1 under visible-light (λ > 420 nm) irradiation in 10 vol% IPA solution. The in-situ generated H 2 O 2 can be activated to produce reactive oxygen species (ROS), especially 1O 2 , to effectively kill the Escherichia coli , reaching an improved an antibacterial rate of 89.7% under stimulated sunlight irradiation in 1 h. This work could offer a new insight into the photoinduced ROS for aqueous H 2 O 2 photosynthesis and antibacterial application. A colloidal K+ intercalated crystalline carbon nitride (KCCN) photocatalyst with abundant surface functional groups (including –OH, –C N groups) was fabricated for photocatalytic H 2 generation, H 2 O 2 production with isopropanol (IPA) oxidation to acetone (AC), and in situ sterilization. The obtained CN photocatalyst indicated accelerated charge separation and transfer in both in-plane and interlayer of carbon nitride, improved surface wettability and rich N-defects, leading to significantly enhanced photocatalytic H 2 O 2 generation with IPA oxidation activities, along with improved in situ antibacterial effect. [Display omitted] • The crystalline carbon nitride was altered by KCl-assisted thermal treatments. • A colloidal hydrophilic surface of carbon nitride nanosheets was achieved. • The generated 1O 2 species was participated in H 2 O 2 production and sterilization. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) often faces salt stress and delayed sowing practices. These two events usually occur simultaneously in real field conditions that cause severe consequences on mineral balance, osmotic adjustment, reactive oxygen species (ROS) rampaging and antioxidant machinery. To address these issues, a two-year field-based study was directed at Jalalpur Pirwala Research Farm (JPRF), Multan-Pakistan. The experiment consisted of the following factors, a) timely sown under normal conditions (NS) and late sowing under normal conditions (LS) b) timely sown on saline conditions and late sown under saline conditions (LS+SS) c) foliar application of plant growth promoters hydrogen peroxide (H 2 O 2), salicylic acid (SA), thiourea (TU) and control (no spray) firstly to assess the influence of plant growth promoters (PGPRs) on the nutrient acquisition, osmoprotectants metabolism, ROS homeostasis and antioxidant clustering under SS, LS and their combined treatments. Results revealed that PGPRs foliar applications such as TU, followed by SA and H 2 O 2 played plausible roles in maintaining nutrient balance, osmoregulation, and circumventing the ROS. Exogenous application of TU increases the proline (18.24–20.01 %), total free amino acids (29.09 %-33.99 %), glycine betaine (3.43 %-15.34 %), total -soluble proteins (10.98 % -15.96 %) and total soluble sugars (15.21 %-20.36 %) for both years, under control conditions. Moreover, LS+SS followed by SS and LS declined the grain nutrient quality, shoot mineral content, and demolished the equilibrium between ROS and antioxidants, however, plants up-regulate the defensive mechanisms by enhancing the substantial content of antioxidants and osmoprotectants. So, wheat is moderately tolerant to combined LS+SS stress that evidently deteriorates its nutritional quality, but its performance can be enhanced by using PGPRs in delayed-sown wheat that often grows in marginally saline areas. [Display omitted] • Late-sown wheat faces severe nutrient imbalance under saline conditions. • Nutrient acquisition and, antioxidant metabolism play key role in wheat tolerance. • Plant growth promoters (PGPRs) improved the defence mechanisms and combat the effect of combined stress. • PGPRs maintain the nutrient balance and osmoregulation in late-sown wheat under salt stress. [ABSTRACT FROM AUTHOR]

Death of vascular smooth muscle cells (VSMC) induced by reactive oxygen species (ROS) may occur as ferroptosis, contributing to atherosclerotic plaque instability and rupture. Although it is involved in ROS-induced VSMC death, the role of nuclear transcription factors erythroid 2 related factor 2 (NRF2) in ferroptosis remains unclear. This study was designed to determine the coupling between NRF2 and antioxidant ferroptosis suppressor protein 1 (FSP1) in ROS-induced VSMC ferroptosis. We exposed mouse aortic VSMCs to hydrogen peroxide (H 2 O 2), and cell death was characterized by increased NRF2 expression and inhibition of FSP1 expression. The results demonstrated that VSMC exposure to H 2 O 2 emerged as the characteristic of ferroptosis·H 2 O 2 promoted the expression and nuclear translocation of NRF2 and downregulated FSP1 expression. These data imply a novel and important role for NRF2/FSP1 in ferroptosis for treating VSMCs ferroptosis-associated diseases. [Display omitted] • Hydrogen peroxide induces VSMCs ferroptosis. • Hydrogen peroxide promoted the expression of NRF2, down-regulating the expression of FSP1. • Hydrogen peroxide induces ferroptosis in VSMCs by NRF2/FSP1 axis. [ABSTRACT FROM AUTHOR]

Sonodynamic therapy (SDT) is emerging as a promising modality for cancer treatment. However, improving the tumor bioavailability and anti-hypoxia capability of sonosensitizers faces a big challenge. In this work, we present a tumor microenvironment (TME)-mediated nanomorphology transformation and oxygen (O 2) self-production strategy to enhance the sonodynamic therapeutic efficacy of tumors. A smart probe Ce6-Leu@Mn2+ that consists of a glutathione (GSH) and leucine amino peptidase (LAP) dual-responsive unit, a 2-cyanobenzothiazole (CBT) group, and a Mn2+-chelated Ce6 as sonosensitizer for tumor SDT was synthesized, and its SDT potential for liver tumor HepG2 in living mice was systematically studied. It was found that the probes could self-assemble into large nanoparticles in physiological condition and spontaneously transformed into small particles under the dual stimulation of GSH and LAP in TME resulting in enhanced tumor accumulation and deep penetration. More notably, Ce6-Leu@Mn2+ could convert endogenous hydrogen peroxide to O 2 , thereby alleviating the hypoxia and achieving effective SDT against hypoxic tumors under the excitation of ultrasound. We thus believe this smart TME-responsive probe may provide a noninvasive and efficient means for malignant tumor treatment. Sonodynamic therapy (SDT) is emerging as a promising therapeutic modality for cancer treatment. However, how to improve the tumor bioavailability and anti-hypoxia capability of sonosensitizers remains a huge challenge. Herein, we rationally developed a theranostic probe Ce6-Leu@Mn2+ that can transform into small-size nanoparticles from initial large particles under the dual stimulation of LAP and GSH in tumor microenvironment (TME) resulting in enhanced tumor accumulation, deep tissue penetration as well as remarkable O 2 self-production for enhanced sonodynamic therapy of human liver HepG2 tumor in living mice. This smart TME-responsive probe may provide a noninvasive and efficient means for hypoxic tumor treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

The electrocatalytic properties of copper selenide for hydrogen peroxide detection in a gas phase were investigated using cyclic and square-wave voltammetry. Copper selenide demonstrated significant electrocatalytic activity towards hydrogen peroxide oxidation in a basic medium containing polyacrylic acid as a gas-absorbing polyelectrolyte. Experimental data were corroborated by a brief theoretical analysis and simulations based on a two-electron irreversible electrode mechanism of a dissolved redox couple. The voltammetric response of a conventional glassy carbon electrode modified with copper selenide showed a linear correlation with hydrogen peroxide concentration over a range of 3.0 × 10−5 to 1.0 × 10−3 mol L−1 in solution. Practical application of this method for gaseous hydrogen peroxide detection was explored using screen-printed electrodes (SPE) coated with a thin film of polyacrylic acid containing medium, with copper selenide serving as a modifier of the working electrode. The detectable concentration range of gaseous hydrogen peroxide using the modified SPE spanned picomolar concentrations. The statistical parameters of the calibration line in terms of LOQ, LOD and R 2 are 4.1 × 10−6, 1.2 × 10−6 mol L−1, and 0.996, which correspond very closely to the gas concentrations of 6.1 × 10−12 to 6.1 × 10−11 mol L−1. The H 2 O 2 is detected not only in the solution phase via CV and SWV, but also measured in gas phase via SWV with SPE modified with copper selenide nanobelts as an electrocatalyst for the oxidation of H 2 O 2. [Display omitted] • Copper selenide based H 2 O 2 detection in gas phase with theoretical verification. • PAA plays major role for the adsorption of gaseous H 2 O 2 from environment. • The catalyst show capability for the detection up to sub-micromole. • The high response is due to the combination of unique features of Cu and Se. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalase in Leptomonas seymouri is present in the cytoplasm and a subset of glycosomes. • Cytoplasmic retention of L. seymouri catalase is H 2 O 2 -dependent. • The ablation of catalase in this parasite is not detrimental in vivo. • Catalase overexpression resulted in a substantially higher parasite load in experimental infection of Dysdercus peruvianus. Nearly all aerobic organisms are equipped with catalases, powerful enzymes scavenging hydrogen peroxide and facilitating defense against harmful reactive oxygen species. In trypanosomatids, this enzyme was not present in the common ancestor, yet it had been independently acquired by different lineages of monoxenous trypanosomatids from different bacteria at least three times. This observation posited an obvious question: why was catalase so "sought after" if many trypanosomatid groups do just fine without it? In this work, we analyzed subcellular localization and function of catalase in Leptomonas seymouri. We demonstrated that this enzyme is present in the cytoplasm and a subset of glycosomes, and that its cytoplasmic retention is H 2 O 2 -dependent. The ablation of catalase in this parasite is not detrimental in vivo, while its overexpression resulted in a substantially higher parasite load in the experimental infection of Dysdercus peruvianus. We propose that the capacity of studied flagellates to modulate the catalase activity in the midgut of its insect host facilitates their development and protects them from oxidative damage at elevated temperatures. [ABSTRACT FROM AUTHOR]

We have found recently that two-step intrinsic hydroxyl radical (·OH)-dependent chemiluminescence (CL) could be produced by carcinogenic tetrahaloquinone and H 2 O 2. However, the first-step CL was too fast to clearly detect the stepwise generation of ·OH and CL, and to distinguish the exact dividing point between the first-step and second-step CL. Here we found that, extremely clear two-step intrinsic CL could be produced by the relative slow reaction of tetrabromohydroquinone (TBHQ) with H 2 O 2 , which was directly dependent on the two-step ·OH generation. Interestingly, the second-step, but not the first-step CL production of TBHQ/H 2 O 2 (CRET donor) was markedly enhanced by fluorescein (a typical xanthene dye, CRET acceptor) through a unique chemiluminescence resonance energy transfer (CRET) process. The novel CRET system of TBHQ/H 2 O 2 /fluorescein was successfully applied for the sensitive detection of TBHQ with the detection limit as low as 2.5 µmol/L. These findings will help to develop more sensitive and highly efficient CL or CRET systems and specific CL sensor to detect the carcinogenic haloquinones, which may have broad environmental applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Colorectal cancer (CRC), a widespread malignancy, is closely associated with tumor microenvironmental hydrogen peroxide (H 2 O 2) levels. Some clinical trials targeting H 2 O 2 for cancer treatment have revealed its paradoxical role as a promoter of cancer progression. Investigating the dynamics of cancer cell H 2 O 2 eustress at the single–cell level is crucial. In this study, non–contact hopping probe mode scanning ion conductance microscopy (HPICM) with high-sensitive Pt–functionalized nanoelectrodes was employed to measure dynamic extracellular to intracellular H 2 O 2 gradients in individual colorectal cancer Caco–2 cells. We explored the relationship between cellular mechanical properties and H 2 O 2 gradients. Exposure to 0.1 or 1 mmol/L H 2 O 2 eustress increased the extracellular to intracellular H 2 O 2 gradient from 0.3 to 1.91 or 3.04, respectively. Notably, cellular F–actin–dependent stiffness increased at 0.1 mmol/L but decreased at 1 mmol/L H 2 O 2 eustress. This H 2 O 2 –induced stiffness modulated AKT activation positively and glutathione peroxidase 2 (GPX2) expression negatively. Our findings unveil the failure of some H 2 O 2 -targeted therapies due to their ineffectiveness in generating H 2 O 2 , which instead acts eustress to promote cancer cell survival. This research also reveals the complex interplay between physical properties and biochemical signaling in cancer cells' antioxidant defense, illuminating the exploitation of H 2 O 2 eustress for survival at the single–cell level. Inhibiting GPX and/or catalase (CAT) enhances the cytotoxic activity of H 2 O 2 eustress against CRC cells, which holds significant promise for developing innovative therapies targeting cancer and other H 2 O 2 - related inflammatory diseases. [ABSTRACT FROM AUTHOR]

A critical feature of the cellular antioxidant response is the induction of gene expression by redox-sensitive transcription factors. In many cells, activating these transcription factors is a dynamic process involving multiple redox steps, but it is unclear how these dynamics should be measured. Here, we show how the dynamic profile of the Schizosaccharomyces pombe Pap1 transcription factor is quantifiable by three parameters: signal amplitude, signal time and signal duration. In response to increasing hydrogen peroxide concentrations, the Pap1 amplitude decreased while the signal time and duration showed saturable increases. In co-response plots, these parameters showed a complex, non-linear relationship to the mRNA levels of four Pap1-regulated genes. We also demonstrate that hydrogen peroxide and tert -butyl hydroperoxide trigger quantifiably distinct Pap1 activation profiles and transcriptional responses. Based on these findings, we propose that different oxidants and oxidant concentrations modulate the Pap1 dynamic profile, leading to specific transcriptional responses. We further show how the effect of combination and pre-exposure stresses on Pap1 activation dynamics can be quantified using this approach. This method is therefore a valuable addition to the redox signalling toolbox that may illuminate the role of dynamics in determining appropriate responses to oxidative stress. [Display omitted] • Redox transcription factors (TF) play critical roles in the antioxidant response. • It is unclear how to measure redox TF signals from dynamic activation profiles. • Fission yeast Pap1 profiles were quantified by signal amplitude, time and duration. • Pap1 dynamics facilitate a graded response to different oxidative inputs. • Redox signal dynamics may an important feature of redox regulation. [ABSTRACT FROM AUTHOR]

Although numerous experimental studies on a hybrid thruster have been recently executed, a fuel port pressure was rarely measured because a gap between a fuel and a fuel case is complicated to be sealed due to a fuel port pressure sensor hole. Therefore, the hybrid thruster with an exposed solid fuel was applied to install a fuel port pressure sensor without the fuel case. An exposed solid fuel hydrogen peroxide catalytic decomposition hybrid thruster with PE (PolyEthylene) and PMMA (PolyMethyl MethAcrylate) as fuels, H 2 O 2 as an oxidizer, MnO 2 /Al 2 O 3 as a catalyst for the oxidizer, 20 bar as a combustion chamber pressure, and 5 s as a burning time was organized. Combustion tests without fuel port pressure sensors to discern an effect of them and with PMMA to visualize a combustion were performed. A fuel port pressure distribution was satisfactorily measured. Three phenomena of four fuel port pressures and a post-combustion chamber pressure in a steady state included an increase at the beginning, a maintenance at the middle, and a decrease at the end induced by a variable oxidizer mass flow rate, a flame generation, and a fuel regression respectively. • Application of exposed solid fuel to install fuel port pressure sensor on fuel. • Combustion visualization to explain occasional error solved by hydraulic fluid. • Increase of fuel port pressure at beginning due to variable oxidizer mass flow rate. • Maintenance of fuel port pressure at middle due to flame generation. • Decrease of fuel port pressure at end due to fuel regression. [ABSTRACT FROM AUTHOR]

We present an innovative modular fabrication method for a green monopropellant thruster, employing printed circuit boards (PCB) as fundamental building blocks for rapid and efficient performance optimization. This PCB-based approach offers superior thermal and structural characteristics to conventional MEMS-based microthrusters. Furthermore, it streamlines mass production and facilitates the swift and reliable assembly of thrusters using well-established PCB surface mount technology. In this study, we present a conceptual demonstration of this pioneering materials and fabrication technique, exemplified by the development of a 200 mN thrust monopropellant thruster utilizing 90 wt% hydrogen peroxide. Subsequently, we conduct propulsion experiments and consistently observe identical patterns in pulse mode firing tests, demonstrating the repeatability of the system. The experimental results, including thrust and C * efficiencies, provide substantial evidence for the validity and feasibility of our proposed approach. The modular fabrication method presented in this study exhibits high potential for mass production of small satellite thrusters, effectively addressing the expanding thruster market. [Display omitted] • Novel approach to thruster fabrication using Lego-like PCB blocks. • Modular monopropellant thrusters with desired performances. • Cost-effective and simple solution compared to conventional methods. • Stable performance, high efficiency, and negligible nozzle erosion. • Potential for mass production of diverse small satellite thrusters. [ABSTRACT FROM AUTHOR]

The present study examines the advancements of a promising low-toxicity hypergolic propellant combination called HIP_11 for in-space applications, developed as alternative to common hypergolic toxic propellants. The fuel is based on an ionic liquid, storable, stable and simple to handle at ambient conditions, developed at the Institute of Space Propulsion, German Aerospace Centre (DLR). The compound shows hypergolicity behaviour when in contact with Hydrogen Peroxide and is a promising substitution to conventional hypergolic propellants. The present work describes the advancements in the development of HIP_11 through a dedicated experimental investigation of various components, analysing and investigating the performances. The experiments are based on a small modulable thruster that allowed to study the efficiency and stability of combustion of the propellant combination while varying various design parameters of the thruster. Specifically, the effects of different injector designs, as well as variations in combustion chamber shape, characteristic length, and operating pressure have been thoroughly examined and analysed. • Experimental testing of a novel green hypergolic propellant for in-space propulsion. • Investigation of multiple design alternatives for critical components. • Analysis of multiple injector and combustion chamber designs in hot-firing tests. • Evaluation of combustion performance in terms of combustion efficiency and stability. • Enhanced combustion stability noted for short and slender combustion chambers with impinging injectors. [ABSTRACT FROM AUTHOR]

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The study investigates, numerically, the potential use of introducing aqueous H 2 O 2 as an ignition promoter in a statistically homogeneous NH 3 /H 2 fuelled, medium speed (1250 rpm), 4-stroke, 1.3 litre cylinder displacement, mildly boosted CI engine with a compression ratio of 17.6:1. The H 2 is considered to be produced on-board from ammonia cracking. An extensive campaign is undertaken using the commercial stochastic reactor model, SRM Engine Suite, which allowed the modelling of temporal, temperature and spatial stratification in the cylinder. The engine performance, combustion phasing, maximum pressure rise rate and emissions (NOx, N 2 O and unreacted NH 3) are investigated in view of: (i) the share of molecular hydrogen in the initial NH 3 /H 2 mixture from 10 to 40 percent; (ii) the mass of aqueous H 2 O 2 introduced from 0.1 to 16 mg; (iii) the start of injection (−10 to ＋6 CAD aTDC) and duration of injection (1, 4 and 8 CAD); (iv) the amount of exhaust gas recirculation (up to 30 percent by mass); (v) the share of energy from the H 2 O 2 in the aqueous solution mixture at less than 0.5 percent of that in the main fuel; (vi) engine load corresponding to a variation in the equivalence ratio from 0.32 to 1.2 by changing the mass of the NH 3 /H 2 mixture in the combustion chamber. A wide range of loads (evaluated against the engine's rated power when operated with diesel and at its rated boost levels) can be achieved (44%–93%) with the energy share of H 2 O 2 being as little as equivalent to 2.7% vol% that of the main fuel, ammonia, which is introduced into the cylinder. This implies that the required storage volume of the H 2 O 2 is low, at a few percent that of the main ammonia tank. NOx emissions peak between ϕ = 0.6−0.65 and rapidly decrease as the equivalence ratio increases or decreases reaching values marginally above the Tier III standard at high loads (> 90%) while ammonia slip and N 2 O emissions are generally extremely low (10−12 mg for NH 3 and < 0.01 mg/kWh for N 2 O). • Aqueous H 2 O 2 pilot ignites NH 3 /H 2 mixture (80/20/vol) with BDC state of 1.3 bar, 390K. • We report engine operation with 1 – 4 mg of aqueous H 2 O 2 pilot at 10% vol%. • A wide range of engine loads can be achieved (44%–93%), without any optimisation. • The maximum pressure rise rate, N 2 O and NH 3 slip are within acceptable limits. • NOx peak at global ϕ ≈ 0.6 and reach marginally above Tier III standard under high load. [ABSTRACT FROM AUTHOR]

Lightweight porous geopolymers are a widely researched system with diverse engineering applications. This study presents a comparative investigation on the strength and pore structure characteristics (including pore size distribution, porosity, morphology and pore wall structure) of porous geopolymers with the same densities (0.60, 0.75 and 0.90 g/cm3) synthesized using pre-foaming (PFG) and H 2 O 2 foaming (HFG) methods for the first time. Various techniques, such as XCT, SEM and MIP, were used to characterise their pore structure at multiple scales. The experimental results demonstrate that PFG exhibits slightly higher compressive strength compared to that of HFG with the same density, which is attributed to the relatively lower macro-pore porosity and more uniform micron-scale (>10 μm) pore structure. Moreover, there are more micron-scale pores and less small capillaries and gel pores (<100 nm) in HFG compared to PFG. Stable foam bubbles can be introduced directly into fresh geopolymers through the pre-foaming method, whereas H 2 O 2 foaming results in the formation of a more unevenly distributed porous system through the decomposition of hydrogen peroxide and the merging of bubbles. This study serves to deepen the comprehension of the foaming process and underlying mechanisms of these two foaming methods, offering new valuable insights into fabricating porous geopolymers with target pore structures in specific engineering applications. [ABSTRACT FROM AUTHOR]

Drought has a direct impact on rice growth performance at various stages. Nevertheless, the impact of nanoparticles on the rice seedlings under drought stress remained limited. Thus, a laboratory experiment was conducted to investigate the effects of different concentrations (300, 600, and 900 mg/L) of silica nanoparticles (SiNPs) on morpho-histological and biochemical features of two rice varieties (UMT-R and MR219) under drought stress (15 % PEG). The findings indicated a substantial reduction due to drought stress in the growth, protein, and antioxidant enzymes, while increasing the proline, malondialdehyde (MDA), and hydrogen peroxide (H 2 O 2) content, and negatively affecting the root histology. Results showed that SiNPs at 600 mg/L were managed to improve plant growth, root vigour, and enzymatic antioxidant levels. Under SiNPs treated plants, among UMT-R and MR219, the proline (1.947 and 1.748 in leaves, 2.010 and 1.890 U/mg protein in roots), peroxidase (POD) (2.850 and 3.512 in leaves, 2.521 and 2.952 U/mg protein in roots), superoxide dismutase (SOD) (3.958 and 4.558 in leaves, 4.296 and 4.606 U/mg protein in roots), and catalase (CAT) (2.171 and 2.289 in leaves, 1.897 and 2.050 U/mg protein in roots) were higher than the drought stress conditions. Meanwhile, the nonenzymatic antioxidant, MDA (0.974 and 0.812 in leaves, 0.842 and 0.778 U/mg Protein in roots), and H 2 O 2 (1.378 and 1.229 in leaves, 1.280 and 1.054 U/mg Protein in roots) showed an opposite trend. SiNPs application noticeably enhanced the histological features of roots under drought conditions. The current findings suggested that SiNPs at 600 mg/L can mitigate the adverse impacts of drought stress and enhance the plant's resistance. Further study should be carried out on the reproductive stage and post-harvest performance of drought-stress rice treated with SiNPs. [Display omitted] • SiNPs treatment significantly increased plant growth under drought conditions. • SiNPs have a significant effect on the root histological traits. • SiNPs significantly enhance protein, proline, SOD, POD, and CAT content. • UMT-R was more sensitive to drought stress as compared to MR219. [ABSTRACT FROM AUTHOR]

Wheat is affected by various biotic and abiotic stresses, especially salinity, which reduces the growth and yield drastically. High salinity is a major constraint for wheat productivity in many countries, including Bangladesh. With this view, here, an experiment was conducted to observe genotypic differences in physiological, ion accumulation, agro-morphological and yield performance of wheat against different levels of salinity. Experimental variables consisted of five salt tolerant genotypes (G 20–2–2, G 20–1–2, G 13–2, G 22–2, G 9–2), one susceptible genotype (G 24–2) and one standard check variety (BARI ghom 25), which assigned to four levels of salinity with electrical conductivities control (0.3), 4, 8 and 12 dS m −1. Irrespective of genotypes, salinity stress significantly decreased the yield and yield attributes. Results of analyses based on salt tolerance indices of plant growth related and yield contributing parameters, ionic balance (Na+, K + and Na+ / K + ratio), and stress indicators such as chlorophyll content, photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr) revealed genotypes G 20–2–2, G 13–2 and G 20–1–2 as salt tolerant, genotype G 9–2 as moderately salt-tolerant and G 24–2 and G 22–2 as salt-sensitive genotypes. Additionally, lower accumulations of hydrogen peroxide and malondialdehyde, and higher activities of antioxidant enzymes in the salt-tolerant genotypes G 20–2–2 and G 13–2 than in the salt-sensitive genotype G 24–2 indicated reduced oxidative damage in genotypes G 20–2–2 and G 13–2 relative to that in genotype G 24–2. Collectively, our findings suggest that the optimum growth and yield of salt tolerant genotypes are associated with decreased Na+/ K + ratio, increased antioxidant enzymes activity and reduced oxidative stress. [Display omitted] [ABSTRACT FROM AUTHOR]

Batrachochytrium dendrobatidis (Bd) is a lethal amphibian pathogen, partly due to its ability to evade the immune system of susceptible frog species. In many pathogenic fungi, the antioxidant glutathione is a virulence factor that helps neutralise oxidative stressors generated from host immune cells, as well as other environmental stressors such as heavy metals. The role of glutathione in stress tolerance in Bd has not been investigated. Here, we examine the changes in the glutathione pool after stress exposure and quantify the effect of glutathione depletion on cell growth and stress tolerance. Depletion of glutathione repressed growth and release of zoospores, suggesting that glutathione is essential for life cycle completion in Bd. Supplementation with <2 mM exogenous glutathione accelerated zoospore development, but concentrations >2 mM were strongly inhibitory to Bd cells. While hydrogen peroxide exposure lowered the total cellular glutathione levels by 42 %, glutathione depletion did not increase the sensitivity to hydrogen peroxide. Exposure to cadmium increased total cellular glutathione levels by 93 %. Glutathione-depleted cells were more sensitive to cadmium, and this effect was attenuated by glutathione supplementation, suggesting that glutathione plays an important role in cadmium tolerance. The effects of heat and salt were exacerbated by the addition of exogenous glutathione. The impact of glutathione levels on Bd stress sensitivity may help explain differences in host susceptibility to chytridiomycosis and may provide opportunities for synergistic therapeutics. • Buthionine sulfoximine (BSO) inhibits glutathione synthesis in chytrid fungi. • Zoospore production is affected by glutathione depletion and supplementation. • Glutathione concentration and ratio change in response to stress. • Cadmium tolerance is affected by glutathione availability. [ABSTRACT FROM AUTHOR]

Enterovirus D68 (EV-D68), a pathogen that causes respiratory symptoms, mainly in children, has been implicated in acute flaccid myelitis, which is a poliomyelitis-like paralysis. Currently, there are no licensed vaccines or treatments for EV-D68 infections. Here, we investigated the optimal viral inactivation reagents, vaccine adjuvants, and route of vaccination in mice to optimize an inactivated whole-virion (WV) vaccine against EV-D68. We used formalin, β -propiolactone (BPL), and hydrogen peroxide as viral inactivation reagents and compared their effects on antibody responses. Use of any of these three viral inactivation reagents effectively induced neutralizing antibodies. Moreover, the antibody response induced by the BPL-inactivated WV vaccine was enhanced when adjuvanted with cytosine phosphoguanine oligodeoxynucleotide (CpG ODN) or AddaVax (MF59-like adjuvant), but not with aluminum hydroxide (alum). Consistent with the antibody response results, the protective effect of the inactivated WV vaccine against the EV-D68 challenge was enhanced when adjuvanted with CpG ODN or AddaVax, but not with alum. Further, while the intranasal inactivated WV vaccine induced EV-D68-specific IgA antibodies in the respiratory tract, it was less protective against EV-D68 challenge than the injectable vaccine. Thus, an injectable inactivated EV-D68 WV vaccine prepared with appropriate viral inactivation reagents and an optimal adjuvant is a promising EV-D68 vaccine. [ABSTRACT FROM AUTHOR]

Silicon (Si) as silicic acid, Si(OH) 4 offers several benefits to the growth of plants, especially under adverse environmental conditions. Therefore, the present study aimed to assess the role of exogenous Si treatments (0.5 and 1.0 mM) in the tolerance of Fagopyrum esculentum Moench to Al stress applied at two different concentrations (0.2 and 0.4 mM). A set of agrophysiological, biochemical and antioxidant parameters were evaluated during the investigation. The exogenous Si application to Fagopyrum esculentum plants exposed to Al treatments significantly modulated the physiological and antioxidant responses to overcome the Al phytotoxicity and provide beneficial effects. The results indicated that the application of different doses of Al significantly affected the physiological parameters viz., plant growth, tolerance index, biomass accumulation (BA), relative water content (RWC), lipid peroxidation (LP), membrane stability index (MSI) and reduced glutathione (GSH) content. Likewise, aluminum-treated leaves also displayed increased hydrogen peroxide accumulation signifying the extent of the damage in F. esculentum. However, the individual and combined doses of silicon (Si) yielded beneficial effects on the physiological and antioxidant attributes. Multivariate analysis also suggested that individual and combined doses of Si improved physiological (root length (RL), shoot length (SL), root and shoot tolerance index (TI), BA, RWC, MSI and osmolytes) and modulates antioxidant defense enzymes (SOD, APX, GPX, CAT, GR and GST). The study reveals that exogenous Si application acts as a potent stress-modulating agent either via the formation of aluminum-silicate complexes or by improving the efficiency of antioxidant enzymatic activities in Al-contaminated soils. Graphical abstract of the proposed mechanism of Si-mediated Al detoxification in Fagopyrum esculentum plants [Display omitted] • Hydroxyl aluminum-silicate (HAS) complex formation in the rhizosphere is the key factor in reducing plant heavy metals (HM) uptake. • Al-treated leaves exhibit increased hydrogen peroxide (H 2 O 2) accumulation vs. silicon (Si) treated leaves. • Exogenous Si treatment modulates osmolytes and antioxidant defense mechanisms. [ABSTRACT FROM AUTHOR]

This paper explores the relevance of a new class of upper stages commonly referred to as Orbital Transfer Vehicles (OTVs) or Kick-Stages, and the importance of green propellants in the development of such systems. Orbital Transfer Vehicles are currently developed for diverse applications by many entities and are expected to have a major impact in the future of space missions and overall space sector. Such systems are commonly connected to the topic of On-Orbit Servicing with the promise of unlocking new missions, including active space debris removal, multi-payload to multi-orbit delivery, in-orbit experiments, in-orbit refuelling and other generic services. Green propulsion is an increasingly prevalent trend in the space industry that has experienced significant growth in recent decades with the main objective of identifying suitable alternatives to commonly used, toxic liquid propellants for in-space applications. The study investigates the synergies between the two themes, underlining the advantages that a widespread use of green technologies could bring to the overall sector, but also examining the final benefits to the system design of OTVs. Due to the numerous and challenging propulsive system requirements associated with these systems, green technologies are analysed to determine their advantages and disadvantages in comparison with current concepts, outlining current trends and expected future developments. The focus is on attainable performances of propulsion systems with respect to the required dry and inert mass. Various architectures of the different green alternatives based on hydrogen peroxide and the more peculiar self-pressurized propellants are proposed, exploring green propellants-based designs that can offer synergies and advantages over classical ones. These new architectures offer performance comparable to classical and widely available toxic alternatives and present the important advantage of using easy-to-handle propellants. The development of such new options has the potential to enable innovative future designs by improving mass and size requirements of new propulsion systems, thereby enhancing the current landscape. • Orbital Transfer Vehicles are emerging in the space sector as enabling technology. • The propulsion systems of Orbital Transfer Vehicles are crucial for the success of their missions. • Green Propellants offer various synergies possibly advantageous for new OTV designs. • Green Propellants perform well against toxic alternatives, but have less heritage. • Multiple design choices based on green propellants are proposed and compared. [ABSTRACT FROM AUTHOR]

Ferroptosis, a unique iron-dependent mode of cell death characterized by lipid peroxide accumulation, holds significant potential for the treatment of glioblastoma (GBM). However, the effectiveness of ferroptosis is hindered by the limited intracellular ferrous ions (Fe2+) and hydrogen peroxide (H 2 O 2). In this study, a novel near-infrared (NIR)-light-responsive nanoplatform (ApoE-UMSNs-GOx/SRF) based on upconversion nanoparticles (UCNPs) was developed. A layer of mesoporous silica and a lipid bilayer were coated on UCNPs sequentially and loaded with glucose oxidase (GOx) and sorafenib, respectively. Further attachment of the ApoE peptide endowed the nanoplatform with BBB penetration and GBM targeting capabilities. Our results revealed that ApoE-UMSNs-GOx/SRF could efficiently accumulated in the orthotopic GBM and induce amplified ferroptosis when combining with NIR irradiation. The UCNPs mediated the photoreduction of Fe3+ to Fe2+ by converting NIR to UV light, and excess H 2 O 2 was produced by the reaction of glucose with the loaded GOx. These processes greatly promoted the production of ROS, which together with inhibition of system Xc− by the loaded sorafenib, leading to enhanced accumulation of lipid peroxides and significantly improved the antiglioma effect both in vitro and in vivo. Our strategy has the potential to enhance the effectiveness of ferroptosis as a therapeutic approach for GBM. A novel nanoplatform (ApoE-UMSNs-GOx/SRF) for the efficient treatment of glioblastoma through NIR-promoted enhanced ferroptosis. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present study, we examined the mitochondrial hydrogen peroxide (mH2O2) generating capacity of α-ketoglutarate dehydrogenase (KGDH) and compared it to components of the electron transport chain using liver mitochondria isolated from male and female C57BL6N mice. We show for the first time there are some sex dimorphisms in the production of mH2O2 by electron transport chain complexes I and III when mitochondria are fueled with different substrates. However, in our investigations into these sex effects, we made the unexpected and compelling discovery that 1) KGDH serves as a major mH2O2 supplier in male and female liver mitochondria and 2) KGDH can form mH2O2 when liver mitochondria are energized with fatty acids but only when malate is used to prime the Krebs cycle. Surprisingly, 2-keto-3-methylvaleric acid (KMV), a site-specific inhibitor for KGDH, nearly abolished mH2O2 generation in both male and female liver mitochondria oxidizing palmitoyl-carnitine. KMV inhibited mH2O2 production in liver mitochondria from male and female mice oxidizing myristoyl-, octanoyl-, or butyryl-carnitine as well. S1QEL 1.1 (S1) and S3QEL 2 (S3), compounds that inhibit reactive oxygen species generation by complexes I and III, respectively, without interfering with OxPhos and respiration, had a negligible effect on the rate of mH2O2 production when pyruvate or acyl-carnitines were used as fuels. However, inclusion of KMV in reaction mixtures containing S1 and/or S3 almost abolished mH2O2 generation. Together, our findings suggest KGDH is the main mH2O2 generator in liver mitochondria, even when fatty acids are used as fuel. [ABSTRACT FROM AUTHOR]

Colon mucosal overexpression of reactive oxygen and nitrogen species (RONS) accelerates the development of inflammatory bowel disease (IBD) and destroys the mucosa and its barrier. IBD can be alleviated by removing RONS from the inflamed colon. The preparation of strong and efficient nanoantioxidants remains a challenge despite the development of numerous nanoantioxidants. In this paper, Zn-TA nanoparticles with fine hollow microstructure (HZn-TA) were successfully prepared and could be effectively used to treat IBD. In the first step, ZIF-8 nanoparticles were synthesized by a one-pot method. On this basis, HZn-TA nanoparticles were etched by TA, and a multifunctional nanase was developed for the treatment of IBD. RONS, including reactive oxygen species (ROS) and nitric oxide (NO), can be eliminated to increase cell survival following Hydrogen peroxide (H 2 O 2) stimulation, including reactive oxygen species (ROS) and nitric oxide (NO with hydrogen peroxide (H 2 O 2). In a model for preventing and delaying acute colitis, clearance of RONS has been shown to reduce intestinal inflammation in mice by reducing colon damage, proinflammatory cytokine levels, the spleen index, and body weight. Intestinal mucosal healing can be promoted by HZn-TA nanoparticles, which can upregulate zonula occludens protein 1 (ZO-1) and claudin-1 expression. Based on the results of this study, HZn-TA nanoparticles were able to effectively treat IBD with minimal adverse effects by being biocompatible, multienzyme active, and capable of scavenging RONS. Therefore, we pioneered the application of HZn-TA nanoparticles for the treatment of IBD, which are capable of clearing RONS without significant adverse effects. ➢ HZn-TA nanoparticles were successfully prepared and could be effectively used to treat IBD. ➢ Intestinal mucosal healing can be promoted by HZn-TA nanoparticles, which can upregulate ZO-1 and claudin-1 expression. ➢ HZn-TA nanoparticles were able to effectively treat IBD with minimal adverse effects by being biocompatible, multienzyme active, and capable of scavenging RONS. [Display omitted] [ABSTRACT FROM AUTHOR]

• Cu 2 O with different morphologies was applied for H 2 O 2 activation. • The cubic Cu 2 O showed the highest activity for TC degradation. • The surface oxygen species play an important role for H 2 O 2 adsorption. • Hydroxyl radicals, carbonate radicals and Cu(III) were the main active species. • Possible TC degradation mechanism was proposed. The design of efficient heterogeneous catalysts in bicarbonate-activated hydrogen peroxide systems (BAP) is a hot topic in wastewater treatment. In this work, Cu 2 O nanoparticles with different morphologies including cubic shape (c-Cu 2 O), octahedron shape (o-Cu 2 O) and spherical shape (s-Cu 2 O), were applied in BAP for the first time to degrade tetracycline hydrochloride (TC). Compared with Cu2+ ions and CuO, TC degradation was boosted in the presence of Cu 2 O in the BAP system, with the degradation rate following the order c-Cu 2 O > o-Cu 2 O > s-Cu 2 O. The morphology-dependent effects could be linearly correlated with the ratio of surface oxygen species (O S), but not with the surface area or Cu(I) ratio. The c-Cu 2 O catalyst with exposure of (100) facets contained 76.6% O S as the active site for H 2 O 2 adsorption and activation, while the value was much lower for o-Cu 2 O and s-Cu 2 O with dominant (111) facets. The presence of HCO 3 − enhanced the interactions among Cu 2 O, H 2 O 2 and TC, leading to facile oxidation of Cu(I) to Cu(II) by H 2 O 2 , and the formation of various reactive species such as hydroxyl radicals and Cu(III) contributed to TC degradation. This work provides a new method for enhancing H 2 O 2 activation with heterogeneous catalysts by crystal facet engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

• Exogenous IAA (25 µM) and/or H 2 O 2 (350 µM) regulates seedling growth, Na+/K+ homeostasis, and H 2 S metabolism in etiolated sunflower seedlings. • Exogenous auxin (IAA) and/or H 2 O 2 treatment recovered both root length and lateral root proliferation under NaCl stress (120 mM). • IAA and H 2 O 2 modules H 2 S content in seedling roots and cotyledons and impact l -DES activity. • TIBA disrupts the internal auxin gradient in roots and reverse the positive effects of exogenous IAA. Although H 2 S has been reported to modulate auxin and H 2 O 2 signaling during abiotic stress, no reports decipher the interactive roles of exogenous auxin and H 2 O 2 on the regulation of endogenous H 2 S homeostasis. In the present work, auxin (IAA) and hydrogen peroxide (H 2 O 2) interaction appear to be crucial in regulating Na+/K+ homeostasis, recovery in seedling growth and H 2 S accumulation in NaCl-stressed sunflower seedlings. Interestingly, impairment in endogenous IAA transport (TIBA application) also impacts H 2 S accumulation in the roots and cotyledons. IAA supplementation is effective in reducing Na+/K+ ratio and electrolytic leakage in roots, which reverses in the presence of TIBA (polar auxin transport inhibitor) application. IAA and H 2 O 2 -mediated modulation of H 2 S content corroborates with l -DES activity in seedling roots and cotyledons. In contrast to cotyledons, roots exhibited a reduction in H 2 S content in the presence of treatments (IAA and H 2 O 2). H 2 O 2 supplementation seems to partially circumvent the changes caused by the disruption of auxin transport. Thus, we hypothesize that auxin might imply H 2 O 2 as a crucial signaling component in the regulation of H 2 S levels in sunflower tissues. To sum up, IAA and H 2 O 2 interaction regulates root growth, LR proliferation, Na+/K+ ratio, and H 2 S metabolism in sunflower seedling roots. [ABSTRACT FROM AUTHOR]