Redispersing Ir Nanoparticles via a Carbon-Assisted Pyrolysis Process to Break the Activity-Stability Trade-Off of H2 Sensors.

Oxide semiconductor-supported metal nanoparticles often suffer from a high-temperature gas sensing process, resulting in agglomeration and coalescence, which significantly decrease their surface activity and stability. Here, we develop an in situ pyrolysis strategy to redisperse commercial Ir particles (∼15.6 nm) into monodisperse Ir species (∼5.4 nm) on ZnO supports, exhibiting excellent sintering-resistant properties and H2 sensing. We find that large-size Ir nanoparticles can undergo an unexpected splitting decomposition process and spontaneously migrate along the encapsulated carbon layer surface during high-temperature pyrolysis of ZIF-8. This resultant monodisperse status can be integrally reserved, accompanying further oxidation sintering. The final Irred/ZnO-450-based sensor exhibits outstanding stability, H2 response (10-2000 ppm), fast response/recovery capability (7/9.7 s@100 ppm), and good moisture resistance. In situ Raman and ex situ XPS further experimentally verify that highly dispersive Ir species can promote the electron transfer process during the gas sensing process. Our strategy thus provides important insights into the design of agglomeration-resistant gas sensing materials for highly effective H2 detection.

Cryo-electron microscopy reveals hydrogen positions and water networks in photosystem II.

Photosystem II starts the photosynthetic electron transport chain that converts solar energy into chemical energy and thus sustains life on Earth. It catalyzes two chemical reactions: water oxidation to molecular oxygen and plastoquinone reduction. Coupling of electron and proton transfer is crucial for efficiency; however, the molecular basis of these processes remains speculative owing to uncertain water binding sites and the lack of experimentally determined hydrogen positions. We thus collected high-resolution cryo-electron microscopy data of fully hydrated photosystem II from the thermophilic cyanobacterium Thermosynechococcus vestitus to a final resolution of 1.71 angstroms. The structure reveals several previously undetected partially occupied water binding sites and more than half of the hydrogen and proton positions. This clarifies the pathways of substrate water binding and plastoquinone B protonation.

Molecular hydrogen promotes retinal vascular regeneration and attenuates neovascularization and neuroglial dysfunction in oxygen-induced retinopathy mice.

BACKGROUND: Retinopathy of Prematurity (ROP) is a proliferative retinal vascular disease occurring in the retina of premature infants and is the main cause of childhood blindness. Nowadays anti-VEGF and retinal photocoagulation are mainstream treatments for ROP, but they develop a variety of complications. Hydrogen (H2) is widely considered as a useful neuroprotective and antioxidative therapeutic method for hypoxic-ischemic disease without toxic effects. However, whether H2 provides physiological angiogenesis promotion, neovascularization suppression and glial protection in the progression of ROP is largely unknown.This study aims to investigate the effects of H2 on retinal angiogenesis, neovascularization and neuroglial dysfunction in the retinas of oxygen-induced retinopathy (OIR) mice. METHODS: In this study, mice that were seven days old and either wild-type (WT) or Nrf2-deficient (Nrf2-/-) were exposed to 75% oxygen for 5 days and then returned to normal air conditions. Different stages of hydrogen gas (H2) inhalation were administered. Vascular obliteration, neovascularization, and blood vessel leakage were analyzed and compared. To count the number of neovascularization endothelial nuclei, routine HE staining of retinal sections was conducted. Immunohistochemistry was performed using DyLight 594 labeled GSL I-isolectin B4 (IB4), as well as primary antibodies against proliferating cell nuclear antigen (PCNA), glial fibrillary acidic protein (GFAP), and Iba-1. Western blots were used to measure the expression of NF-E2-related factor 2 (Nrf2), vascular endothelial growth factor (VEGF), Notch1, Dll4, and HIF-1α. Additionally, the expression of target genes such as NQO1, HO-1, Notch1, Hey1, Hey2, and Dll4 was measured. Human umbilical vein endothelial cells (HUVECs) treated with H2 under hypoxia were used as an in vitro model. RT-PCR was used to evaluate the mRNA expression of Nrf2, Notch/Dll4, and the target genes. The expression of reactive oxygen species (ROS) was observed using immunofluorescence staining. RESULTS: Our results indicate that 3-4% H2 does not disturb retinal physiological angiogenesis, but ameliorates vaso-obliteration and neovascularization in OIR mice. Moreover, H2 prevents the decreased density and reverses the morphologic and functional changes in retinal astrocytes caused by oxygen-induced injury. In addition, H2 inhalation reduces microglial activation, especially in the area of neovascularization in OIR mice. H2 plays a protective role in vascular regeneration by promoting Nrf2 activation and suppressing the Dll4-induced Notch signaling pathway in vivo. Also, H2 promotes the proliferation of HUVECs under hypoxia by negatively regulating the Dll4/Notch pathway and reducing ROS levels through Nrf2 pathway aligning with our findings in vivo.Moreover, the retinal oxygen-sensing mechanisms (HIF-1α/VEGF) are also involved in hydrogen-mediated retinal revascularization and neovascularization suppression. CONCLUSIONS: Collectively, our results indicate that H2 could be a promising therapeutic agent for POR treatment and that its beneficial effect in human ROP might involve the activation of the Nrf2-Notch axis as well as HIF-1α/VEGF pathways.

Hydrogen-Rich Alkaline Water Supplementation Restores a Healthy State and Redox Balance in H2O2-Treated Mice.

Water is a major requirement for our bodies, and alkaline water has induced an antioxidant response in a model of natural aging. A series of recent reports have shown that aging is related to reduced water intake. Hydrogen-rich water has been suggested to exert a general antioxidant effect in relation to both improving lifestyle and preventing a series of diseases. Here, we wanted to investigate the effect of the daily intake of hydrogen-rich alkaline water (HAW) in counteracting the redox imbalance induced in a model of H2O2-treated mice. Mice were treated with H2O2 for two weeks and either left untreated or supplied with HAW. The results show that HAW induced a reduction in the ROS plasmatic levels that was consistent with the increase in the circulating glutathione. At the same time, the reduction in plasmatic 8-hydroxy-2'-deoxyguanosine was associated with reduced DNA damage in the whole body. Further analysis of the spleen and bone marrow cells showed a reduced ROS content consistent with a significantly reduced mitochondrial membrane potential and superoxide accumulation and an increase in spontaneous proliferation. This study provides evidence for a clear preventive and curative effect of HAW in a condition of systemic toxic condition and redox imbalance.

Modeling the Initiation Phase of the Catalytic Cycle in the Glycyl-Radical Enzyme Benzylsuccinate Synthase.

The reaction of benzylsuccinate synthase, the radical-based addition of toluene to a fumarate cosubstrate, is initiated by hydrogen transfer from a conserved cysteine to the nearby glycyl radical in the active center of the enzyme. In this study, we analyze this step by comprehensive computer modeling, predicting (i) the influence of bound substrates or products, (ii) the energy profiles of forward- and backward hydrogen-transfer reactions, (iii) their kinetic constants and potential mechanisms, (iv) enantiospecificity differences, and (v) kinetic isotope effects. Moreover, we support several of the computational predictions experimentally, providing evidence for the predicted H/D-exchange reactions into the product and at the glycyl radical site. Our data indicate that the hydrogen transfer reactions between the active site glycyl and cysteine are principally reversible, but their rates differ strongly depending on their stereochemical orientation, transfer of protium or deuterium, and the presence or absence of substrates or products in the active site. This is particularly evident for the isotope exchange of the remaining protium atom of the glycyl radical to deuterium, which appears dependent on substrate or product binding, explaining why the exchange is observed in some, but not all, glycyl-radical enzymes.

Effect of Orally Ingested Water Containing H2-Filled Ultrafine Bubbles (UFBs) on Ethanol-Induced Oxidative Stress in Rats.

Ultrafine bubbles (UFBs), which are bubbles with diameters of less than 1 µm, are widely recognized for their ability to exist stably in liquid as a result of the effects of Brownian motion. In this study, we focused on hydrogen, known for its antioxidant potential, and explored the function of H2-filled UFBs, which encapsulate hydrogen, to determine their potential use as oral carriers for the delivery bioactive gases to living organisms. To this end, rats were orally administered ethanol to induce hepatic oxidative stress, and the effects of drinking H2-filled UFBs (H2 NanoGAS®) water for two weeks were evaluated to assess the reduction of oxidative stress. Continuous alcohol consumption was found to significantly increase the blood lipid peroxidation levels in the control group, confirming the induction of oxidative stress. An increase in blood lipid peroxidation was significantly inhibited by the consumption of concentrated H2 NanoGAS® (C-HN) water. Furthermore, the measurement of mitochondrial activity in the liver revealed that drinking H2 NanoGAS® water helped to maintain at a normal level and/or boosted the functional activity of the electron transport system in mitochondria affected by ethanol intake. To our knowledge, this study is the first to provide evidence for the use of orally ingested UFBs as carriers for the delivery gases to tissues, thereby exerting their physiological activity in the body. Our findings highlight the potential for the application of UFBs to various physiologically active gases and their utilization in the medical field in the future.

Biohydrogen utilization in legume-rhizobium symbiosis reveals a novel mechanism of accelerated tetrachlorobiphenyl transformation.

Symbiosis between Glycine max and Bradyrhizobium diazoefficiens were used as a model system to investigate whether biohydrogen utilization promotes the transformation of the tetrachlorobiphenyl PCB77. Both a H2 uptake-positive (Hup+) strain (wild type) and a Hup- strain (a hupL deletion mutant) were inoculated into soybean nodules. Compared with Hup- nodules, Hup+ nodules increased dechlorination significantly by 61.1 % and reduced the accumulation of PCB77 in nodules by 37.7 % (p < 0.05). After exposure to nickel, an enhancer of uptake hydrogenase, dechlorination increased significantly by 2.2-fold, and the accumulation of PCB77 in nodules decreased by 54.4 % (p < 0.05). Furthermore, the tetrachlorobiphenyl transformation in the soybean root nodules was mainly testified to be mediated by nitrate reductase (encoded by the gene NR) for tetrachlorobiphenyl dechlorination and biphenyl-2,3-diol 1,2-dioxygenase (bphC) for biphenyl degradation. This study demonstrates for the first time that biohydrogen utilization has a beneficial effect on tetrachlorobiphenyl biotransformation in a legume-rhizobium symbiosis.

Simultaneous Formate and Syngas Conversion Boosts Growth and Product Formation by Clostridium ragsdalei.

Electrocatalytic CO2 reduction to CO and formate can be coupled to gas fermentation with anaerobic microorganisms. In combination with a competing hydrogen evolution reaction in the cathode in aqueous medium, the in situ, electrocatalytic produced syngas components can be converted by an acetogenic bacterium, such as Clostridium ragsdalei, into acetate, ethanol, and 2,3-butanediol. In order to study the simultaneous conversion of CO, CO2, and formate together with H2 with C. ragsdalei, fed-batch processes were conducted with continuous gassing using a fully controlled stirred tank bioreactor. Formate was added continuously, and various initial CO partial pressures (pCO0) were applied. C. ragsdalei utilized CO as the favored substrate for growth and product formation, but below a partial pressure of 30 mbar CO in the bioreactor, a simultaneous CO2/H2 conversion was observed. Formate supplementation enabled 20-50% higher growth rates independent of the partial pressure of CO and improved the acetate and 2,3-butanediol production. Finally, the reaction conditions were identified, allowing the parallel CO, CO2, formate, and H2 consumption with C. ragsdalei at a limiting CO partial pressure below 30 mbar, pH 5.5, n = 1200 min-1, and T = 32 °C. Thus, improved carbon and electron conversion is possible to establish efficient and sustainable processes with acetogenic bacteria, as shown in the example of C. ragsdalei.

Minimal and hybrid hydrogenases are active from archaea.

Microbial hydrogen (H2) cycling underpins the diversity and functionality of diverse anoxic ecosystems. Among the three evolutionarily distinct hydrogenase superfamilies responsible, [FeFe] hydrogenases were thought to be restricted to bacteria and eukaryotes. Here, we show that anaerobic archaea encode diverse, active, and ancient lineages of [FeFe] hydrogenases through combining analysis of existing and new genomes with extensive biochemical experiments. [FeFe] hydrogenases are encoded by genomes of nine archaeal phyla and expressed by H2-producing Asgard archaeon cultures. We report an ultraminimal hydrogenase in DPANN archaea that binds the catalytic H-cluster and produces H2. Moreover, we identify and characterize remarkable hybrid complexes formed through the fusion of [FeFe] and [NiFe] hydrogenases in ten other archaeal orders. Phylogenetic analysis and structural modeling suggest a deep evolutionary history of hybrid hydrogenases. These findings reveal new metabolic adaptations of archaea, streamlined H2 catalysts for biotechnological development, and a surprisingly intertwined evolutionary history between the two major H2-metabolizing enzymes.

Hydrogen isotope fractionation is controlled by CO2 in coccolithophore lipids.

Hydrogen isotope ratios (δ2H) represent an important natural tracer of metabolic processes, but quantitative models of processes controlling H-fractionation in aquatic photosynthetic organisms are lacking. Here, we elucidate the underlying physiological controls of 2H/1H fractionation in algal lipids by systematically manipulating temperature, light, and CO2(aq) in continuous cultures of the haptophyte Gephyrocapsa oceanica. We analyze the hydrogen isotope fractionation in alkenones (αalkenone), a class of acyl lipids specific to this species and other haptophyte algae. We find a strong decrease in the αalkenone with increasing CO2(aq) and confirm αalkenone correlates with temperature and light. Based on the known biosynthesis pathways, we develop a cellular model of the δ2H of algal acyl lipids to evaluate processes contributing to these controls on fractionation. Simulations show that longer residence times of NADPH in the chloroplast favor a greater exchange of NADPH with 2H-richer intracellular water, increasing αalkenone. Higher chloroplast CO2(aq) and temperature shorten NADPH residence time by enhancing the carbon fixation and lipid synthesis rates. The inverse correlation of αalkenone to CO2(aq) in our cultures suggests that carbon concentrating mechanisms (CCM) do not achieve a constant saturation of CO2 at the Rubisco site, but rather that chloroplast CO2 varies with external CO2(aq). The pervasive inverse correlation of αalkenone with CO2(aq) in the modern and preindustrial ocean also suggests that natural populations may not attain a constant saturation of Rubisco with the CCM. Rather than reconstructing growth water, αalkenone may be a powerful tool to elucidate the carbon limitation of photosynthesis.

Protocol for preparation of electrifiable carbon membrane reactor for non-oxidative alkane dehydrogenation.

A membrane reactor (MR) offers a solution to overcome thermodynamic equilibrium limitations by enabling in situ product separation, enhancing product yields and energy efficiency. Here we present a protocol for synthesizing a carbon MR that couples a H2-permeable carbon molecular sieve hollow fiber membrane and a metal supported on zeolite catalyst for non-oxidative propane and ethane dehydrogenation. We describe steps for catalyst preparation, membrane fabrication, and MR construction. The as-developed MR has significant improvements in alkene yield and a record-high stability. For complete details on the use and execution of this protocol, please refer to Liu et al.1.

Enhanced Mineralization of Organic Pollutants through Atomic Hydrogen-Mediated Alternative Transformation Pathways.

Electrocatalytic hydrogen atom-hydroxyl radical (H*-·OH) redox system is a promising approach for contaminant removal and mineralization. However, its working mechanism, especially the effect of H*, remains unclear, hindering its practical application. Herein, we constructed an electrochemical reactor equipped with our self-made Pd-loaded Ti/TiO2 nanotube cathode and a commercial boron-doped diamond anode. After fulfilling the electrode characterization and free radical detection, we employed coumarin and 7-azido-4-methylcoumarin as probes to confirm the participation of H* in the transformation of organic compounds. A comprehensive study on the degradation kinetics, reaction, and mineralization mechanisms using benzoic acid (BA) and 4-chlorophenol (4-CP) as model compounds was further conducted. The rate constants and total organic carbon removal of BA and 4-CP in the redox system increased compared with those of the individual oxidation and reduction processes. Theoretical calculations demonstrate that H* opens up alternative pathways for BA and 4-CP ring cleavage, forming quinones as reactive intermediates. Furthermore, H* facilitates the mineralization of the typical intermediates, maleic acid and fumaric acid, through C=C bond addition and H-abstraction from the 1,1-diol structure. The presence of H* provides alternative pathways for pollutant transformation, consequently reducing the treatment duration.

Antibiotic fermentation residue for biohydrogen production: Inhibitory mechanisms of the inherent antibiotic.

Antibiotic fermentation residue, which is generated from the microbial antibiotic production process, has been a troublesome waste faced by the pharmaceutical industry. Dark fermentation is a potential technology to treat antibiotic fermentation residue in terms of renewable H2 generation and waste management. However, the inherent antibiotic in antibiotic fermentation residue may inhibit its dark fermentation performance, and current understanding on this topic is limited. This investigation examined the impact of the inherent antibiotic on the dark H2 fermentation of Cephalosporin C (CEPC) fermentation residue, and explored the mechanisms from the perspectives of bacterial communities and functional genes. It was found that CEP-C in the antibiotic fermentation residue significantly inhibited the H2 production, with the H2 yield decreasing from 17.2 mL/g-VSadded to 12.5 and 9.6 mL/g-VSadded at CEP-C concentrations of 100 and 200 mg/L, respectively. CEP-C also prolonged the H2-producing lag period. Microbiological analysis indicated that CEP-C remarkably decreased the abundances of high-yielding H2-producing bacteria, as well as downregulated the genes involved in hydrogen generation from the"pyruvate pathway" and"NADH pathway", essentially leading to the decline of H2 productivity. The present work gains insights into how cephalosporin antibiotics influence the dark H2 fermentation, and provide guidance for mitigating the inhibitory effects.

Nitrate reduction to nitrogen in wastewater using mesoporous carbon encapsulated Pd-Cu nanoparticles combined with in-situ electrochemical hydrogen evolution.

The conversion of NO3--N to N2 is of great significance for zero discharge of industrial wastewater. Pd-Cu hydrogenation catalysis has high application prospects for the reduction of NO3--N to N2, but the existing form of Pd-Cu, the Pd-Cu mass ratio and the H2 evolution rate can affect the coverage of active hydrogen (*H) on the surface of Pd, thereby affecting N2 selectivity. In this work, mesoporous carbon (MC) is used as support to disperse Pd-Cu catalyst and is applied in an in-situ electrocatalytic H2 evolution system for NO3--N removal. The Pd-Cu particles with the average size of 6 nm are uniformly encapsulated in the mesopores of MC. Electrochemical in-situ H2 evolution can not only reduce the amount of H2 used, but the H2 bubbles can also be efficiently dispersed when PPy coated nickel foam (PPy/NF) is used as cathode. Moreover, the mesoporous structure of MC can further split H2 bubbles, reducing the coverage of *H on Pd. The highest 77% N2 selectivity and a relatively faster NO3--N removal rate constant (0.10362 min-1) can be achieved under the optimal conditions, which is superior to most reported Pd-Cu catalytic systems. The prepared catalyst is further applied to the denitrification of actual deplating wastewater. NO3--N with the initial concentration of 650 mg L-1 can be completely removed after 180 min of treatment, and the TN removal can be maintained at 72%.

Switchable and conspicuous retroreflective sensors inspired by the wing scale of an emerald swallowtail.

Butterfly wings possess distinct micro/nanostructures that contribute to their vibrant coloration, light-trapping capabilities, and sensitivity to various stimuli. These complex features have inspired the creation of diverse devices and systems, such as sensors, photovoltaics, photocatalysis, and robotics. Specifically, the wing scales of the Emerald Swallowtail (Papilio palinurus) display iridescent, polarization-sensitive, and retroreflective colors due to their hierarchical structures. However, current technologies fail to mimic these natural designs fully, limiting their practical application in everyday life. In this study, we introduce a groundbreaking method for fabricating artificial wing scales that emulate the biological structure's functionality with a much simpler geometry. By integrating self-graded lossy media into metallic micro-concavity arrays, we achieve pronounced iridescent effects in both coaxial and non-coaxial arrangements, while preserving retroreflective properties. In particular, the simplified design allows for switchable color patterns based on the viewing angle. Demonstrating the concept, we successfully employ these conspicuous retroreflectors in hydrogen gas detection and the bi-directional/switchable recognition of patterned signals.

Hydrogen-rich water alleviates constipation by attenuating oxidative stress through the sirtuin1/nuclear factor-erythroid-2-related factor 2/heme oxygenase-1 signaling pathway.

BACKGROUND: Constipation, a highly prevalent functional gastrointestinal disorder, induces a significant burden on the quality of patients' life and is associated with substantial healthcare expenditures. Therefore, identifying efficient therapeutic modalities for constipation is of paramount importance. Oxidative stress is a pivotal contributor to colonic dysmotility and is the underlying pathology responsible for constipation symptoms. Consequently, we postulate that hydrogen therapy, an emerging and promising intervention, can serve as a safe and efficacious treatment for constipation. AIM: To determine whether hydrogen-rich water (HRW) alleviates constipation and its potential mechanism. METHODS: Constipation models were established by orally loperamide to Sprague-Dawley rats. Rats freely consumed HRW, and were recorded their 24 h total stool weight, fecal water content, and charcoal propulsion rate. Fecal samples were subjected to 16S rDNA gene sequencing. Serum non-targeted metabolomic analysis, malondialdehyde, and superoxide dismutase levels were determined. Colonic tissues were stained with hematoxylin and eosin, Alcian blue-periodic acid-Schiff, reactive oxygen species (ROS) immunofluorescence, and immunohistochemistry for cell growth factor receptor kit (c-kit), PGP 9.5, sirtuin1 (SIRT1), nuclear factor-erythroid-2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1). Quantitative real-time PCR and western blot analysis were conducted to determine the expression level of SIRT1, Nrf2 and HO-1. A rescue experiment was conducted by intraperitoneally injecting the SIRT1 inhibitor, EX527, into constipated rats. NCM460 cells were induced with H2O2 and treated with the metabolites to evaluate ROS and SIRT1 expression. RESULTS: HRW alleviated constipation symptoms by improving the total amount of stool over 24 h, fecal water content, charcoal propulsion rate, thickness of the intestinal mucus layer, c-kit expression, and the number of intestinal neurons. HRW modulated intestinal microbiota imbalance and abnormalities in serum metabolism. HRW could also reduce intestinal oxidative stress through the SIRT1/Nrf2/HO-1 signaling pathway. This regulatory effect on oxidative stress was confirmed via an intraperitoneal injection of a SIRT1 inhibitor to constipated rats. The serum metabolites, ß-leucine (ß-Leu) and traumatic acid, were also found to attenuate H2O2-induced oxidative stress in NCM460 cells by up-regulating SIRT1. CONCLUSION: HRW attenuates constipation-associated intestinal oxidative stress via SIRT1/Nrf2/HO-1 signaling pathway, modulating gut microbiota and serum metabolites. ß-Leu and traumatic acid are potential metabolites that upregulate SIRT1 expression and reduce oxidative stress.

The GA and ABA signaling is required for hydrogen-mediated seed germination in wax gourd.

BACKGROUND: Hydrogen gas (H2), a novel and beneficial gaseous molecule, plays a significant role in plant growth and development processes. Hydrogen-rich water (HRW) is regarded as a safe and easily available way to study the physiological effects of H2 on plants. Several recent research has shown that HRW attenuates stress-induced seed germination inhibition; however, the underlying modes of HRW on seed germination remain obscure under non-stress condition. RESULTS: In this current study, we investigated the possible roles of gibberellin (GA) and abscisic acid (ABA) in HRW-regulated seed germination in wax gourd (Benincasa hispida) through pharmacological, physiological, and transcriptome approaches. The results showed that HRW application at an optimal dose (50% HRW) significantly promoted seed germination and shortened the average germination time (AGT). Subsequent results suggested that 50% HRW treatment stimulated GA production by regulating GA biosynthesis genes (BhiGA3ox, BhiGA2ox, and BhiKAO), whereas it had no effect on the content of ABA and the expression of its biosynthesis (BhiNCED6) and catabolism genes (BhiCYP707A2) but decreased the expression of ABA receptor gene (BhiPYL). In addition, inhibition of GA production by paclobutrazol (PAC) could block the HRW-mediated germination. Treatment with ABA could hinder HRW-mediated seed germination and the ABA biosynthesis inhibitor sodium tungstate (ST) could recover the function of HRW. Furthermore, RNA-seq analysis revealed that, in the presence of GA or ABA, an abundance of genes involved in GA, ABA, and ethylene signal sensing and transduction might involve in HRW-regulated germination. CONCLUSIONS: This study portrays insights into the mechanism of HRW-mediated seed germination, suggesting that HRW can regulate the balance between GA and ABA to mediate seed germination through ethylene signals in wax gourd.

Cooperation and competition between denitrification and chromate reduction in a hydrogen-based membrane biofilm reactor.

Competition and cooperation between denitrification and Cr(VI) reduction in a H2-based membrane biofilm reactor (H2-MBfR) were documented over 55 days of continuous operation. When nitrate (5 mg N/L) and chromate (0.5 mg Cr/L) were fed together, the H2-MBfR maintained approximately 100 % nitrate removal and 60 % chromate Cr(VI) removal, which means that nitrate outcompeted Cr(VI) for electrons from H2 oxidation. Removing nitrate from the influent led to an immediate increase in Cr(VI) removal (to 92 %), but Cr(VI) removal gradually deteriorated, with the removal ratio dropping to 14 % after five days. Cr(VI) removal resumed once nitrate was again added to the influent. 16S rDNA analyses showed that bacteria able to carry out H2-based denitrification and Cr(VI) reduction were in similar abundances throughout the experiment, but gene expression for Cr(VI)-reduction and export shifted. Functional genes encoding for energy-consuming chromate export (encoded by ChrA) as a means of bacterial resistance to toxicity were more abundant than genes encoding for the energy producing Cr(VI) respiration via the chromate reductase ChrR-NdFr. Thus, Cr(VI) transport and resistance to Cr(VI) toxicity depended on H2-based denitrification to supply energy. With Cr(VI) being exported from the cells, Cr(VI) reduction to Cr(III) was sustained. Thus, cooperation among H2-based denitrification, Cr(VI) export, and Cr(VI) reduction led to sustained Cr(VI) removal in the presence of nitrate, even though Cr(VI) reduction was at a competitive disadvantage for utilizing electrons from H2 oxidation.

Early Hydrogen-Oxygen Gas Mixture Inhalation in Patients with Aneurysmal Subarachnoid Hemorrhage (HOMA): study protocol for a randomized controlled trial.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening neurosurgical emergency with a high mortality rate. Delayed cerebral ischemia (DCI) and cerebral vasospasm (CVS) are delayed products of early brain injury (EBI), which may constitute the principal determinant of an unfavorable patient prognosis. Consequently, the mitigation of DCI and CVS assumes paramount significance in the pursuit of enhanced patient outcomes. However, except for oral nimodipine, there is no effective therapy available in the current guideline. Hence, the exigency arises to proffer novel treatment paradigms. The diversity of hydrogen therapeutic targets has been largely reported in basic research, unveiling its latent capacity to ameliorate EBI in aSAH patients. METHODS: Early Hydrogen-Oxygen Gas Mixture Inhalation in Patients with Aneurysmal Subarachnoid Hemorrhage (HOMA), a single-center, prospective, open-labeled, randomized controlled clinical trial, endeavors to evaluate the efficacy and safety of hydrogen-oxygen gas mixture inhalation therapy in aSAH patients. A cohort of 206 patients will be randomized to either hydrogen-oxygen gas mixture inhalation group (8 h per day, 3 L/min, hydrogen concentration of 67%, oxygen concentration of 33%) or oxygen inhalation group (8 h per day, 3 L/min, oxygen concentration of 33%) within 72 h after aSAH and treated for 7 days in the ICU ward. The primary outcomes are the incidence of DCI and CVS during hospitalization. DISCUSSION: The HOMA aims to evaluate the effectiveness of hydrogen-oxygen gas mixture inhalation therapy in preventing DCI or CVS and improving outcomes in aSAH patients. Notably, this is the first large-scale trial of hydrogen therapy in aSAH patients. Given that the Chinese population represents a significant portion of the global population and the increasing incidence of stroke due to aging, optimizing patient care is vital. Given the current challenges in aSAH patient outcomes, initiating more prospective clinical trials is essential. Recent research has shown hydrogen's therapeutic potential, aligning with EBI in aSAH, driving our exploration of hydrogen therapy's mechanisms in post-aneurysm rupture damage. ETHICS AND DISSEMINATION: The protocol for the HOMA study was approved by the Ethics Committee of Beijing Tiantan Hospital, Capital Medical University (KY 2022-020-02). All results of the present study will be published in peer-reviewed journals and presented at relevant conferences. TRIAL REGISTRATION: ClinicalTrials.gov NCT05282836. Registered on March 16, 2022.

Proton-Coupled Electron Transfer and Hydrogen Tunneling in Olive Oil Phenol Reactions.

Olive oil phenols are recognized as molecules with numerous positive health effects, many of which rely on their antioxidative activity, i.e., the ability to transfer hydrogen to radicals. Proton-coupled electron transfer reactions and hydrogen tunneling are ubiquitous in biological systems. Reactions of olive oil phenols, hydroxytyrosol, tyrosol, oleuropein, oleacein, oleocanthal, homovanillyl alcohol, vanillin, and a few phenolic acids with a DPPH• (2,2-diphenyl-1-picrylhydrazyl) radical in a 1,4-dioxane:water = 95:5 or 99:1 v/v solvent mixture were studied through an experimental kinetic analysis and computational chemistry calculations. The highest rate constants corresponding to the highest antioxidative activity are obtained for the ortho-diphenols hydroxytyrosol, oleuropein, and oleacein. The experimentally determined kinetic isotope effects (KIEs) for hydroxytyrosol, homovanillyl alcohol, and caffeic acid reactions are 16.0, 15.4, and 16.7, respectively. Based on these KIEs, thermodynamic activation parameters, and an intrinsic bond orbital (IBO) analysis along the IRC path calculations, we propose a proton-coupled electron transfer mechanism. The average local ionization energy and electron donor Fukui function obtained for the phenolic compounds show that the most reactive electron-donating sites are associated with π electrons above and below the aromatic ring, in support of the IBO analysis and proposed PCET reaction mechanism. Large KIEs and isotopic values of Arrhenius pre-exponential factor AH/AD determined for the hydroxytyrosol, homovanillyl alcohol, and caffeic acid reactions of 0.6, 1.3, and 0.3, respectively, reveal the involvement of hydrogen tunneling in the process.