H2S Generation Research Articles

Engineered Carbon Nanostructures for Preventing Alzheimer’s Disease

Alzheimer’s disease (AD) is an aging-associated devastating disease that affects over 5 million Americans and imposes an annual economic burden of $236 billion. Currently, all efforts to develop remedies to AD have failed. This unfortunate situation calls for the development of new research directions. One of the common pathological features of AD is the decline in endogenous production of hydrogen sulfide (H2S), a gaseous signaling molecule. H2S in the brain is historically believed to be solely derived via enzymatic production and deficiencies in H2S producing enzymes, such as cystathionine-γ-lyase (CGL) and cystathionine-β-synthase (CBS) are associated with neurodegenerative diseases. Exogenous administration of H2S and H2S donors have shown to attenuate Alzheimer’s and Parkinson’s disease phenotypes in rodent models. However, exogenous H2S gas and donor molecules are short-lived, highly reactive, and display acute toxicity at elevated levels, and delivery to the intended tissue may be challenging to achieve in the clinic. Thus, discovering new technologies that regulate and/or augment endogenous enzymatic H2S pose novel scientific and therapeutic avenues particularly for the treatment of neurodegenerative disorders such as Alzheimer’s disease.We are designing enzyme-mimicking carbon nanostructures (EMCNs) that can augment the production of H2S using biological substrates present in the body and compensate for the declining enzyme activity and prevent the progression of Alzheimer’s disease. Carbon nanostructures with sp2 carbons are composed of multiple electron-deficient double bonds, which can be systematically replaced with functional groups to create a heterogeneous surface that is fundamentally different from that originally present. Based on the sp2 site engineering concept, we selected and synthesized EMCNs capable of interacting with the sulfur-containing biomolecules, catalyzing their breakdown into H2S and other products, thus mimicking CGL and CBS enzymes.The ability of EMCNs to mimic enzymes was evaluated with lead acetate saturated paper-based assay. EMCNs break down cysteine to produce H2S, which reacts with lead acetate to form lead sulfide. The concentration of H2S generated is calculated by using sodium hydrosulfide as an equimolar H2S donor for calibration. The H2S generation from EMCNs can be matched with the CBS enzyme. Further, EMCNs are stable and demonstrate long-term activity. In a repeated exposure experiment, H2S production was constant over a 20 day period where the substrate was added every day without replenishing ECMNs. If EMCNs were a reactant, the H2S production should have decreased with repeated substrate addition until all the EMCN was consumed.The efficacy of EMCNs to produce H2S in vitro was demonstrated with murine neuronal cells. P3 multi-photon fluorescent probe was utilized to detect intracellular H2S levels. The fluorescence intensity of the neuronal cells exposed to EMCN increased in a concentration-dependent manner. Neither cells nor EMCN exhibited auto-fluorescence under multi-photon microscopy. Beta-amyloid (Aβ) plaques, a hallmark of brain pathology in Alzheimer's disease patients, is formed by aggregation of β-amyloid peptides. The role of EMCNs in the AD model was evaluated with β-amyloid toxicity assay using Aβ1-42, which is selectively toxic to neurons. Preliminary studies suggest that EMCNs protect neuronal cells against the toxicity induced by Aβ1-42 by 19%. The ability of EMCNs to produce H2S under physiological conditions thus offers potential for rescuing enzyme deficiencies in Alzheimer’s disease.

ANALYSIS OF FLOWRATE, SULFATE, AND TOTAL SULFUR PATTERN IN WASTEWATER INLET TANKS FOR HS MANAGEMENT

Hydrogen sulfide (H2S) is a major source of concrete corrosion in a wastewater treatment plant (WWTP) that causes significant financial losses. Variations in the flow rate and composition of incoming wastewater has significant impact on H2S generation. During anaerobic conditions, sulfur present in excreta and sulfate from rainfall become the source of electron acceptors for the conversion of sulfate to sulfide in wastewater. Sulfide, in turn, is converted to H2S and later to sulfuric acid which leads to concrete corrosion. Flowrate directly relates to the amount of wastewater entering the plant. Hence understanding flow rate pattern will help to analyze H2S generation. Flow rate and H2S concentrations were recorded every two-hours for four days in a wastewater treatment plant. Wastewater samples of 50ml were collected at each sampling event coinciding the recording intervals. Samples were analyzed for sulphate and sulfide concentrations using HACH© kits. Total sulfur was calculated from the collected data. The correlations were analyzed using Minitab©. It was found out that average flow rate was negatively related to average H2S concentration. H2S concentration is higher during night when the flow rate is lower, which is a result of greater resident time. Flowrate changes in a cyclic manner throughout the day. During night, sulfate and total sulfur concentrations are higher, H2S concentration is maximum during this time. It is contrariwise during the day. Sulfate and total sulfide follow a pattern that is similar to that of flowrate. Analyzing these parameters is a critical step in successfully modelling H2S generation.

Rhamnolipid increases H2S generation from waste activated sludge anaerobic fermentation: An overlooked concern

Rhamnolipid (RL), one representative biosurfactant, is widely regarded as an economically feasible and environmentally beneficial additive to improve fermentation efficiency and resource recovery from waste activated sludge (WAS). However, its potentially detrimental impact on WAS fermentation such as H2S generation was overlooked previously. This study therefore aims to fill the gap through exploring whether and how the presence of RL affects H2S generation from WAS anaerobic fermentation. Experimental results showed that when RL increased from 0 to 40 mg/g total suspended solids (TSS), the cumulative H2S yield enhanced from 323.6 × 10−4 to 620.3 × 10−4 mg/g volatile suspended solids (VSS). Mechanism analysis showed that RL reduced WAS surface tension, which benefited transformations of organic sulfurs (e.g., aliphatic-S and sulfoxide) and inorganic sulfate from solid to liquid phase. The presence of RL not only reduced the ratio of α-helix/(β-sheet + random coil) and damaged the hydrogen bonding networks of organic sulfurs but also promoted substrate surface charges and cell membrane permeability. These facilitated the contact between hydrolase and organic sulfurs, thereby increasing sulfide production from organic sulfurs hydrolysis. Further investigations showed that RL promoted the expression of key genes (e.g., aprA/B and dsrA/B) involved in the dissimilatory sulfate reduction, which accelerated the reaction of adenosine 5’-phosphosulfate (APS)→ sulfite→ sulfide. Meanwhile, RL inhibited the corresponding key genes such as CysH, and Sir, responsible for assimilatory sulfate reduction (APS→3’-phosphoadenosine-5’phosphosulfate→organosulfur), which reduced substrate competition in favor of H2S production from dissimilatory sulfate reduction. Besides, RL decreased the fermentation pH, which benefited the transformation of HS− to H2S.

ANALYSIS OF FLOWRATE, SULFATE, AND TOTAL SULFUR PATTERN IN WASTEWATER INLET TANKS FOR HS MANAGEMENT

Hydrogen sulfide (H2S) is a major source of concrete corrosion in a wastewater treatment plant (WWTP) that causes significant financial losses. Variations in the flow rate and composition of incoming wastewater has significant impact on H2S generation. During anaerobic conditions, sulfur present in excreta and sulfate from rainfall become the source of electron acceptors for the conversion of sulfate to sulfide in wastewater. Sulfide, in turn, is converted to H2S and later to sulfuric acid which leads to concrete corrosion. Flowrate directly relates to the amount of wastewater entering the plant. Hence understanding flow rate pattern will help to analyze H2S generation. Flow rate and H2S concentrations were recorded every two-hours for four days in a wastewater treatment plant. Wastewater samples of 50ml were collected at each sampling event coinciding the recording intervals. Samples were analyzed for sulphate and sulfide concentrations using HACH© kits. Total sulfur was calculated from the collected data. The correlations were analyzed using Minitab©. It was found out that average flow rate was negatively related to average H2S concentration. H2S concentration is higher during night when the flow rate is lower, which is a result of greater resident time. Flowrate changes in a cyclic manner throughout the day. During night, sulfate and total sulfur concentrations are higher, H2S concentration is maximum during this time. It is contrariwise during the day. Sulfate and total sulfide follow a pattern that is similar to that of flowrate. Analyzing these parameters is a critical step in successfully modelling H2S generation.

Geochemical characterization of natural gases in the pre-salt section of the Santos Basin (Brazil) focused on hydrocarbons and volatile organic sulfur compounds

The objective of this work is to characterize the geochemistry of a suite of natural gas samples from five fields in order to improve the understanding of the lacustrine petroleum system of the pre-salt section from the Santos Basin (Brazil). Additionally, the distribution of volatile organic sulfur compounds (VOSC) in petroleum reservoirs was examined to investigate possible applications to petroleum systems assessments. The hydrocarbon gases were generated by thermogenic processes associated with the oil window. The 13C-enriched values for C1 (>−40‰) were interpreted as an organic source signature rather than an indication of thermal maturity, except for the oil occurrence (Field B), where a different fluid charge mainly composed of methane and CO2 from a minor external kitchen area in the Santos Basin was identified. The molecular composition and the carbon and hydrogen isotopic data of the hydrocarbon gases, when combined with the VOSC molecular compositional data, allow the identification of four gas families associated with different kitchens and/or migrations pathways. The total VOSC concentrations range from 0.7 to 23.9 ppm by volume (ppmV). The organic sulfides are mainly composed of carbonyl sulfide (COS) and diethyl sulfide. The main thiol compound is ethanethiol. The cyclic VOSC are primarily composed of thiophene, with a negligible amount of branched thiophenes (<0.1 ppmV). H2S showed a strong positive Pearson's correlation with COS and methanethiol (MeSH) concentrations (r = 0.943 and 0.807, respectively). This suggests that COS and MeSH formation was linked to H2S generation and/or post-catagenetic interactions between hydrocarbons and H2S, mainly related to thermochemical sulfate reduction (TSR). In contrast, the distribution of higher molecular weight VOSC seems to be controlled by source rock facies, rather than H2S concentration. Principal component analysis of the VOSC compositional data identified some subgroups within the gas families mainly associated with TSR. The results presented in this work reveal that VOSC can be an important auxiliary tool in petroleum system studies.

A closer look at SRB souring in porous media: Higher-order finite difference scheme in radial coordinate

Microorganisms have different benefits including bioremediation of aquifers contaminated with the non-aqueous liquid phase, microbial EOR, and bacterial degradation of asphaltenes. Despite these profits, a special kind of bacteria named Sulfate Reducing Bacteria (SRB) causes H2S generation which is toxic and also results in equipment erosion and corrosion. The injected water approaches the production well in a radial form geometry. However, less is known about the H2S generation and movement in the radial coordinate. In this study, we investigated SRB souring in aquifers and oil reservoirs using a reactive numerical simulation of multicomponent and multiphase radial flow. The operator-splitting method was utilized to model this dispersion-dependent phenomenon. Furthermore, a higher-order finite difference approach was adopted to more accurately model SRB souring by avoiding the numerical dispersion. The results of the proposed approach were verified with the existing analytical radial solution by applying the simplifying assumption of the analytical radial solution. Also, the effect of numerical and physical dispersions was evaluated and it was highlighted that under certain conditions numerical dispersion can be confused with the physical one. Moreover, a comparison of the H2S profile in the radial coordinate with linear geometry showed significant differences which should be considered in SRB souring studies. This difference highlights the necessity of radial grid refinement around the wells in full-field reservoir simulation to attain more accuracy. The study of SRB souring during water injection in an oil reservoir also illustrates the same pattern as souring in aquifer but the oil presence delays mixing between sea and formation water and postpones H2S generation. The findings of this work provide a better understanding of near-wellbore SRB souring during water injection in porous media.

Activating transcription factor 6 regulates cystathionine to increase autophagy and restore memory in Alzheimer’ s disease model mice

Endoplasmic reticulum stress (ER stress) plays a crucial role in the process of Alzheimer's disease (AD). Activating transcription factor 6 (ATF6) is a crucial sensor of ER stress. In AD patients, the homeostasis of the endogenous signal H2S produced by cystathionine γ-lyase (CTH) is in disbalance. However, the role of ATF6 and CTH in AD is rarely reported. Herein, we found that ATF6 and CTH were reduced in AD patients and APP/PS1 mice by immunohistochemistry and western blots. In LN229 and U87 MG cells, knockdown of ATF6 attenuated CTH expression, whereas overexpression of ATF6 resulted in upregulation of CTH. Brain-specific ATF6 knockout mice expressed significantly down-regulated CTH in the hippocampus and cortex compared to wild-type mice. Mechanistically, ATF6 and CTH increased H2S generation and autophagy-related proteins. Further we observed that CTH promoted the sulfhydration of αSNAP. This is probably to be the specific mechanism by which AFT6 promotes autophagy. Through in vivo studies, we found that αSNAP sulfhydration expression was significantly lower in ATF6 knockout mice than in wild-type mice. Decreased ATF6 impaired spatial memory retention, while addition of CTH rescued memory loss. Together, we demonstrate that ATF6 positively regulates the expression of CTH, which is closely related to the rescue of AD. Targeting the ATF6/CTH signal pathway may provide a new strategy for the treatment of AD.

Effects of inorganic sulfur species on hydrocarbon conversion and 34S isotope fractionation during thermal maturation of Type II kerogen

Inorganic sulfur (S) species including pyrite (FeS2) and sulfates may co-exist with organic matter (OM) in source rocks. Their inter-related effects on hydrocarbon generation and decomposition, and the 34S isotope fractionation during thermal maturation remain unclear. In this study, four groups of hydrothermal experiments (kerogen with pyrite, kerogen with pyrite and gypsum, kerogen with pyrite removal, and kerogen with pyrite removal and gypsum) were conducted at 330–450 °C and 50 MPa using a gold-tube system. These experiments showed that pyrite and gypsum had limited effect on the determined vitrinite reflectance (%Ro) and H/C of kerogens under hydrothermal conditions. However, the presence of gypsum led to the occurrence of TSR accelerating the decompositions of oil and hydrocarbon gases. TSR also resulted in the apparent increase of gas dryness and sourness, and the enrichment in 13C and 2H of methane. Experimental data confirmed that an equilibrium isotope effect (EIE) was responsible for the small 34S fractionation between H2S and its precursor OM-S during thermal cracking of OM-S. The higher yields and more negative 34S isotopic ratios (δ34S) of H2S in the pyrolysis of kerogen with FeS2 revealed that the decomposition of 34S-depleted FeS2 contributed to H2S generation at elevated temperatures. Additionally, δ34S of pyrolysis products (i.e., oil, H2S and residual kerogens) become much more enriched with TSR. Mass balance calculations suggested that the evolution of δ34S of H2S from TSR in closed systems proceeded in two stages: the kinetic isotope effect (KIE) dominates the 34S fractionation in the early stage of TSR; and 34S exchange between sulfate and H2S is more influential in the latter/higher T stage of TSR. These conclusions may provide additional insights for understanding of 34S isotope fractionation both in hydrothermal settings and in organic-rich shale with multiple S sources.

Novel controlled-release polylactic-co-glycolic acid (PLGA) nanoparticles for sodium thiosulphate, a hydrogen sulphide donor, retains pro-angiogenic potential of hydrogen sulphide

Hydrogen sulphide (H2S) is an endogenous gaseous signalling molecule observing cardioprotective qualities in various experimental models. However, its therapeutic application is limited due to rapid release in vivo and potential toxicity. Controlled-release nanoparticles (NPs), such as polylactic-co-glycolic acid (PLGA) NPs entrapping H2S compounds may address these issues. PLGA NPs’ encapsulating sodium thiosulphate (STS), a H2S donor, were prepared by emulsification and sonication-solvent evaporation in polyvinyl alcohol (PVA). Sonication time was varied between 15 and 45 s and PVA concentration varied between 0.3 and 0.7% w/v. NPs were characterised, cellular uptake, H2S generation and encapsulated STS angiogenic potential was explored. An increase in sonication time as well as PVA concentration decreased NPs size resulting in an increase in STS release kinetics and cellular uptake over 24 h. Encapsulated STS gave a controlled release of H2S over 24 h whereas non-encapsulated STS peaked at 2 h. Finally, we observed entrapped STS maintained pro-angiogenic potential. PLGA NPs are a promising controlled-release delivery system with potential to offer sustained H2S levels. Results of this study demonstrate formulation of STS-loaded PLGA NPs provides a controlled-release of STS and therefore H2S. NPs are internalised into cells and critically, PLGA NPs are able to maintain the pro-angiogenic potential of H2S.

Sulfur Amino Acid Supplementation Abrogates Protective Effects of Caloric Restriction for Enhancing Bone Marrow Regrowth Following Ionizing Radiation.

Radiation therapy damages and depletes total bone marrow (BM) cellularity, compromising safety and limiting effective dosing. Aging also strains total BM and BM hematopoietic stem and progenitor cell (HSPC) renewal and function, resulting in multi-system defects. Interventions that preserve BM and BM HSPC homeostasis thus have potential clinical significance. Here, we report that 50% calorie restriction (CR) for 7-days or fasting for 3-days prior to irradiation improved mouse BM regrowth in the days and weeks post irradiation. Specifically, one week of 50% CR ameliorated loss of total BM cellularity post irradiation compared to ad libitum-fed controls. CR-mediated BM protection was abrogated by dietary sulfur amino acid (i.e., cysteine, methionine) supplementation or pharmacological inhibition of sulfur amino acid metabolizing and hydrogen sulfide (H2S) producing enzymes. Up to 2-fold increased proliferative capacity of ex vivo-irradiated BM isolated from food restricted mice relative to control mice indicates cell autonomy of the protective effect. Pretreatment with H2S in vitro was sufficient to preserve proliferative capacity by over 50% compared to non-treated cells in ex vivo-irradiated BM and BM HSPCs. The exogenous addition of H2S inhibited Ten eleven translocation 2 (TET2) activity in vitro, thus providing a potential mechanism of action. Short-term CR or fasting therefore offers BM radioprotection and promotes regrowth in part via altered sulfur amino acid metabolism and H2S generation, with translational implications for radiation treatment and aging.

Numerical investigation on H2S formation characteristics in air-staging combustion of a tangentially coal-fired boiler

ABSTRACT Existing H2S generation models are mainly applied in laboratory-scale models and thoughtless about the fuel sulfur release characteristics in fuel-rich zone. So, a novel H2S generation model is proposed for describing the H2S formation characteristics of real-scale boilers in this work. It consists of two parts: fuel sulfur release and chemical reactions. The ratio of the gasification rate to the consumption rate for each char particle is calculated in coal combustion model through the user-defined function (UDF) approach, which is delivered to the H2S generation model for determining the proportions of char sulfur converted to COS and SO2. The numerical results show that the proportions of char sulfur converted to H2S are about 0.545 over the excess air coefficient range from 0.6 to 1.2. The strongly reducing atmosphere could just accelerate the H2S formation to a certain extent in the devolatilization stage. For a 600 MW tangentially coal-fired boiler, the H2S concentration over 400 mg∙kg−1 appears mainly in the zone below burner A and the zone between burner E and the separated over-fire air nozzle. This study is intended to guide for predicting possible corrosion zone and delivering targeted solutions for inhibiting metal corrosion.

Hydrogen sulfide attenuates intracellular oxidative stress via repressing glycolate oxidase activities in Arabidopsis thaliana

BackgroundHydrogen sulfide (H2S) has been proposed to exert anti-oxidative effect under many environmental stresses; however, how it influences oxidative stress remains largely unclear. ResultsHere, we assessed the effects of H2S on oxidative stress responses such as salicylic acid (SA)-dependent cell death, which triggered by increased H2O2 availability in Arabidopsis thaliana catalase-deficient mutants cat2 displaying around 20% wild-type catalase activity. H2S generation and its producing enzyme L-cysteine desulfhydrase (LCD/DES) were found to transient increase in response to intracellular oxidative stress. Although introducing the mutation of des1, an important LCD, into the cat2 background produced little effect, H2S fumigation not only rescued the cell death phenotype of cat2 plant, but also attenuated SA accumulation and oxidation of the glutathione pool. Unexpectedly, the activities of major components of ascorbate–glutathione pathway were less affected by the presence of H2S treatment, but decreased glycolate oxidase (GOX) in combination with accumulation of glycolate implied H2S treatment impacts the cellular redox homeostasis by repressing the GOX-catalyzed reaction likely via altering the major GOX transcript levels.ConclusionsOur findings reveal a link between H2S and peroxisomal H2O2 production that has implications for the understanding of the multifaceted roles of H2S in the regulation of oxidative stress responses.

The Impact of Wastewater Quality and Flow Characteristics on H2S Emissions Generation: Statistical Correlations and an Artificial Neural Network Model

Hydrogen sulfide (H2S) is a naturally occurring, highly toxic gas that is formed from the decomposition of sulfur compounds. H2S is a common source of concrete and metal corrosion that results in huge economic losses in wastewater collection and treatment plants. Hence, it is necessary to analyze H2S generation and emission. H2S concentrations were measured at the Al-Saad wastewater treatment plant in the United Arab Emirates. Wastewater samples were collected, and water quality parameters were characterized in the laboratory. Simultaneously, flow characteristics, humidity, headspace airflow, and temperature were measured onsite. A neural network model to predict H2S emissions was formulated using significant parameters. It was observed that flowrate, velocity, sulfate, and total sulfur had a similar cyclic pattern throughout the sampling events. The temperature, humidity, total sulfur, and depth of wastewater were identified as the most important parameters influencing H2S emissions through correlation analysis. The neural model validation and testing had an R value of 0.9. The training had an R value of 0.8. The model provided an accuracy of 80% for the prediction of H2S concentration in wastewater treatment plants. The accuracy can be improved by increasing the data. The model is limited to its applicability in the prediction of H2S emissions under conditions similar to the inlet of a wastewater treatment plant.

Cysteine supplementation enhanced inhibitor tolerance of Zymomonas mobilis for economic lignocellulosic bioethanol production

Inhibitors in lignocellulosic hydrolysates are toxic to Zymomonas mobilis and reduce its bioethanol production. This study revealed cysteine supplementation enhanced furfural tolerance in Z. mobilis with a 2-fold biomass increase. Transcriptomic study illustrated that cysteine biosynthesis pathway was down-regulated while cysteine catabolism was up-regulated with cysteine supplementation. Mutants for genes involved in cysteine metabolism were constructed, and metabolites in cysteine metabolic pathway including methionine, glutathione, NaHS, glutamate, and pyruvate were supplemented into media. Cysteine supplementation boosted glutathione synthesis or H2S release effectively in Z. mobilis leading to the reduced accumulation of reactive oxygen species (ROS) induced by furfural, while pyruvate and glutamate produced in the H2S generation pathway promoted cell growth by serving as the carbon or nitrogen source. Finally, cysteine supplementation was confirmed to enhance Z. mobilis tolerance against ethanol, acetate, and corncob hydrolysate with an enhanced ethanol productivity from 0.38 to 0.55 g−1∙L−1∙h−1.

High-precision prediction of unionized hydrogen sulfide generation based on limited datasets and its impact on anaerobic digestion of sulfate-rich wastewater

Data-driven models can simulate the complex anaerobic digestion (AD) process and predict the production of unionized hydrogen sulfide (H2S), thus improving methane (CH4) production by alleviating the unionized H2S inhibition. However, due to the limitations of model structures and small datasets, traditional data-driven models cannot accurately simulate the production of sulfides and their morphological differentiation process. In this study, by integrating method of deep neural network (DNN) model and random standard deviation sampling (RSDS), a method called RSDS-DNN was established to simulate the generation of unionized H2S in the AD process. The virtual data was generated by the RSDS method based on the mean value and standard calculated from the raw dataset collected from the experiment. Compared with the results of the artificial neural network (ANN) models trained with the raw dataset (the lowest MSE of 464.02 and the lowest MAPE of 29.00% for testing dataset), the DNN model trained with a virtual dataset showed obvious advantages. The DNN model with 2 hidden layers and 100 hidden neurons in each layer trained with a virtual dataset with 1060 samples achieved the best performance with a mean R-square (R2) of 0.978, the minimal MAE of 87.80, and the minimal MAPE of 9.21% for the testing dataset. The Integrated RSDS-DNN model is a potential approach to assist the reducing of unionized H2S production and enhance CH4 production in the AD process.

The influence and optimization of air distribution method on the boiler burns high-sulfur coal

A large amount of H2S will be generated during the operation of power plants mixed combustion with high-sulfur coal, causing high-temperature corrosion of the boiler water-cooled wa ll. In order to prevent it from pipes bursting due to high temperature corrosion during the operation of the unit, Air distribution was adjusted on a 350MW subcritical pulverized coal combustion boiler, especially for the opening of the secondary a ir valves of each layer of the burner, so as to reduce the volume fraction of H2S in the furnace and lower the corrosion of the water-cooled wall. The research results show that by adjusting the a ir distribution, the volume fraction of CO and O2 in the flue gas of the furnace is changed, and at the same time, it also has an influences on the change of the flue ga s temperature in the furnace, a nd effectively inhibits the generation of H2S, a lleviating the high temperature corrosion of water wall.

Insights into potassium permanganate reducing H2S generation from anaerobic fermentation of sludge

• Pretreatment with 0.1 g/g TSS KMnO 4 reduced H 2 S yield from WAS to 67%. • KMnO 4 inhibited sulfur containing organics hydrolysis and sulfate reduction. • KMnO 4 addition changed the chemical equilibrium of sulfide species. • KMnO 4 decreased the related abundances of S 2− producers and functional genes. Potassium permanganate, a versatile strong oxidant, has been applied as a highly effective additive to degrade pollutants and recover resources from Waste activated sludge (WAS). In addition to these benefits, it was observed in this study that KMnO 4 largely reduced H 2 S production from WAS anaerobic fermentation. With an increase of KMnO 4 dosage from 0 to 0.1 g/g TSS, the maximal H 2 S production reduced from 292.3 × 10 −4 to 96.4 × 10 −4 mg/g VSS while the maximal short-chain fatty acids production increased from 23 to 251 mg COD/g VSS. Model-based analysis showed that KMnO 4 decreased the maximal H 2 S yield potential and H 2 S production rate. The mechanism explorations revealed that several oxidative substances (e.g., •O 2 − and •OH), Mn 2+ , and O H - were substantially generated after KMnO 4 being added into the fermenters. The generated oxidative substances resulted in intracellular substance release even cell apoptosis. This inhibited the activities of two main S 2 - (H 2 S precursor) producers, i.e., Sulfate reducing bacteria (SRBs) and anaerobes responsible for hydrolysis of sulfur-containing organics, especially that of SRBs. Experimental results showed that 0.1 g/g TSS KMnO 4 inhibited sulfur-containing organics hydrolysis, amino acids degradation, and sulfate reducing process by 12.5%, 27.2%, and 61.2%, respectively. The Mn 2+ released from KMnO 4 and other metal ions (e.g., Fe 2+ ) originated from metal-binding functional groups owing to KMnO 4 addition caused substantial S-based precipitations, which also decreased S 2 - in the fermentation liquor. Besides, the generated O H - increased fermentation pH, which benefited the chemical equilibrium of sulfide species from H 2 S to H S - and S 2 - . Microbial community and PICRUSt2 analyses further revealed that KMnO 4 significantly decreased the abundances of S 2 - producers and functional genes responsible for sulfate reducing process.

PH-responsive hierarchical H2S-releasing nano-disinfectant with deep-penetrating and anti-inflammatory properties for synergistically enhanced eradication of bacterial biofilms and wound infection

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) biofilm-associated bacterial infection is the primary cause of nosocomial infection and has long been an ongoing threat to public health. MRSA biofilms are often resistant to multiple antimicrobial strategies, mainly due to the existence of a compact protective barrier; thus, protecting themselves from the innate immune system and antibiotic treatment via limited drug penetration.ResultsA hierarchically structured hydrogen sulfide (H2S)-releasing nano-disinfectant was presented, which was composed of a zinc sulfide (ZnS) core as a H2S generator and indocyanine green (ICG) as a photosensitizer. This nano-disinfectant (ICG-ZnS NPs) sensitively responded to the biofilm microenvironment and demonstrated efficient eradication of MRSA biofilms via a synergistic effect of Zn2+, gas molecule-mediated therapy, and hyperthermia. Physically boosted by released H2S and a near-infrared spectroscopy-induced hyperthermia effect, ICG-ZnS NPs destroyed the compactness of MRSA biofilms showing remarkable deep-penetration capability. Moreover, on-site generation of H2S gas adequately ameliorated excessive inflammation, suppressed secretion of inflammatory cytokines, and expedited angiogenesis, therefore markedly accelerating the in vivo healing process of cutaneous wounds infected with MRSA biofilms.ConclusionICG-ZnS NPs combined with NIR laser irradiation exhibited significant anti-biofilm activity in MRSA biofilms, can accelerate the healing process through deep-penetration and anti-inflammatory effectuation. The proposed strategy has great potential as an alternative to antibiotic treatment when combating multidrug-resistant bacterial biofilms.Graphical

Kinetically Orthogonal Probe for Simultaneous Measurement of H2S and Nitroreductase: A Refined Method to Predict the Invasiveness of Tumor Cells

The concentrations of nitroreductase and H2S have been widely used to predict the invasiveness of tumors. However, the above two substrates always interfere with the measurement of each other as both substrates react with the typical nitroaromatic probe with the same process. Moreover, the above interferences may lead to the misjudgment of the tumor invasiveness. We used a strategy combining kinetical distinguishing and signal amplification to construct a kinetically orthogonal probe labeled KOP. The above strategy expanded the gap between the reactivity of KOP to H2S and nitroreductase with an acceptable reactivity and could determine the concentration of coexisting nitroreductase and H2S on a kinetic curve with a breakpoint. KOP could also indicate the correct invasiveness tendency in the cellular model with a complex H2S generation pathway, while the traditional kinetically nonorthogonal probe could not indicate invasiveness correctly.

H2S origin, generation, and distribution in the Etame Marin Permit, offshore Gabon: A three-dimensional migration modeling prediction using field data

H2S origin, generation, and distribution in the Etame Marin Permit, offshore Gabon: A three-dimensional migration modeling prediction using field data