Levels Of H2 Research Articles

A machine learning based regression methods to predicting syngas composition for plasma gasification system

Plasma gasification is considered a promising technology that converts waste into energy through an environmentally friendly process. This research focuses on predicting the outputs of this process, utilizing ML regression techniques. Data from previous studies involving different solid fuels were collected, and four regression techniques Random Forest Regression, Gaussian Process Regression, Decision Tree Regression, and Support Vector Regression were employed to predict the levels of CO2, CO, N2, O2, H2, and CH4 in the plasma gasification process. The experimental dataset was gathered using a microwave gasifier with varying air flow rates (50–100 sL/min) and plasma power (3–6 kW). GPR a coefficient of determination (R2) values exceeding 0.983 for all outputs and low NRMSE and MSLE values (<0.082 and <0.00123, respectively). RFR also performed well, with R2 values >0.98 for all outputs except CH4 and CO2. SVR exhibited the least favorable performance, while DTR showed intermediate results. Plasma gasification Machine Learning modeling has proven to enable the prediction of the high-complexity chemical reaction chain in gasification. These models hold promise for applications in simulation environments and can be integrated into microcontroller-based systems for practical use for optimization and control. By this means, the cost of plasma gasification processes would be reduced, and so the plasma gasification system would be more flexible.

Impact of Diluents on Flame Stability With Blends of Natural Gas and Hydrogen

Abstract Two potential decarbonization pathways for natural gas (NG)-fueled gas turbine engines include blending hydrogen (H2) into NG and postcombustion carbon capture. H2 blending changes several combustion properties, including flame speed and stretch sensitivity. The use of post-combustion carbon capture systems is typically facilitated by the implementation of exhaust gas recirculation (EGR), where exhaust gases are injected into the inlet of the engine, increasing carbon dioxide (CO2) concentration at the outlet and, hence, increasing the efficiency of carbon capture technologies. In this work, we explore the impact of H2 blending and EGR on the stability of a swirl-stabilized, central-piloted flame. Mixtures of NG and H2 are tested at a range of different diluent compositions, with oxygen varied from 21% to 15% by volume in the oxidizer. In all cases, a constant adiabatic flame temperature is maintained to mimic the operation of a gas turbine at a given turbine inlet temperature. A variable-length combustor is used for testing, where combustor length is varied to understand the dynamic stability characteristics of the system. Results show that EGR and H2 work in opposition to each other, where higher levels of EGR result in poor flame holding and higher levels of H2 result in better flame holding. Increasing H2 generally increases the amplitude of thermoacoustic instability at each condition, a result of the change in flame position in this particular combustor. Importantly, H2 can be added to NG to improve flame holding without significantly decreasing CO2 levels in the products, showing that H2 blending can be a method for counteracting combustor operability issues that arise from high levels of EGR necessary to improve the efficiency of typical carbon capture systems.

Hydrogen-natural gas fuel blending in a “rich burn” engine with 3-way catalyst

Interest in hydrogen (H2) fuels is growing, with industry planning to produce it with stranded or excess energy from renewable sources in the future. Natural gas (NG) utility companies are now taking action to blend H2 into their preexisting pipelines to reduce greenhouse gas (GHG) emissions from burning NG. Stoichiometric (“rich burn”) NG engines that operate on pipeline NG and will receive blended fuel as more gas utilities expand H2 production. These engines are typically chosen for their low emissions owing to the 3-way catalyst control, so the focus of this paper is on the change in emissions like carbon monoxide (CO) and nitrogen oxides (NOx) as the fuel is blended with up to 30% H2 by volume. The Caterpillar CG137-8 natural gas engine used for testing was originally designed for industrial gas compression applications and is a good representative for most “rich burn” engines used across industry for applications such as power generation, gas compression, and water pumping. A significant greenhouse gas (GHG) emissions reduction is observed as more H2 is added to the fuel. Increasing H2 in the fuel changes combustion behavior in the cylinder, resulting in faster ignition and higher cylinder pressures, which increase engine-out NOx emissions. Post-catalyst CO and NOx both decrease slightly with increasing H2 while operating at the optimal “air-fuel” equivalence ratio (λ). A “rich burn” engine with 3-way catalyst can tolerate up to 30% H2 (by vol.) while still meeting NOx and CO emissions limits. However, at elevated levels of H2, increased engine-out NOx emissions narrow the λ range of operation. As H2 is added to NG pipelines, some “rich burn” engine systems may require larger catalysts or more precise λ control to accommodate the increased NOx production associated with a H2-NG blend. Sudden step-increases in H2 cause dramatic changes in λ, resulting in large emissions of post-catalyst NOx during the transition. Comparable changes in H2 at elevated concentrations cause larger spikes in NOx than at lower concentrations. Better tuned engine controllers respond more quickly and produce less NOx during H2 step-transitions.

Frustrated Lewis pairs on hollow flower-liked carbon nitride by phosphorous and tungsten co-doping to enhance photocatalytic performance

Frustrated Lewis pairs (FLPs) exhibit a distinctive “push-pull” effect that efficiently triggers the activation of diverse molecules, leading to unforeseen catalytic capabilities. In this study, phosphotungstic acid (PTA) is introduced into graphitic carbon nitride (g-C3N4). Here, phosphorus (P) as the Lewis acid (LA) site, while the electron-rich N-active site neighboring tungsten (W) assumes the role of the Lewis base (LB) site, giving g-C3N4 a FLPs-like property. The formation of FLPs creates a robust “pull-push” effect, thereby improving the separation of photogenerated carriers. This prepared CNW-20 sample demonstrates effective photocatalytic capabilities for hydrogen (H2) evolution and for degrading organic pollutants. Production levels of H2 reached up to 1044.36 μmol h−1·g−1, surpassing the bulk g-C3N4 by a factor of 14. Concurrently, the efficiency of CNW-20 sample in degrading tetracycline hydrochloride (TC) reached 83.40 %. This study introduces a novel approach for the systematic design of FLP sites on metal-doped photocatalysts, aiming to enhance the efficiency of H2 generation and the degradation of pollutants.

An investigation on the H2O, unburned H2 and NO emission characteristics from a direct injection hydrogen engine

Hydrogen engines show great potential as a power source with good combustion performance, zero carbon emissions, and diverse sources. However, the exhaust emission characteristics with high water vapor (H2O) content have not yet been clarified. This study presents the exhaust emissions of a heavy-duty direct-injection hydrogen engine under various operational parameters, with a focus on the H2O content. The results reveal important exhaust emissions characteristics of the hydrogen engine, including lower exhaust temperature (200 °C–400 °C), higher unburned H2 emissions (up to 17100 ppm), less nitrogen oxide (NO) generation (<1000 ppm), and higher H2O content (6%–40%). Additionally, unburned H2 rises, and NO and H2O decrease as the excess air ratio (λ) increases. When λ is greater than 3, NO levels fall sharply to below 100 ppm. Optimal emissions performance is achieved with a 5 °CA BTDC ignition timing where low levels of H2, H2O, and NO are maintained. Increasing hydrogen injection pressure decreases H2 but raises exhaust temperature, H2O, and NO emissions. Excessively delaying hydrogen injection timing adversely affects the concentration gradient in the cylinder, increasing unburned H2 emissions. The best emissions performance is observed at a hydrogen injection timing of 110 °CA BTDC.

Metagenome mining and functional analysis reveal oxidized guanine DNA repair at the Lost City Hydrothermal Field.

The GO DNA repair system protects against GC → TA mutations by finding and removing oxidized guanine. The system is mechanistically well understood but its origins are unknown. We searched metagenomes and abundantly found the genes encoding GO DNA repair at the Lost City Hydrothermal Field (LCHF). We recombinantly expressed the final enzyme in the system to show MutY homologs function to suppress mutations. Microbes at the LCHF thrive without sunlight, fueled by the products of geochemical transformations of seafloor rocks, under conditions believed to resemble a young Earth. High levels of the reductant H2 and low levels of O2 in this environment raise the question, why are resident microbes equipped to repair damage caused by oxidative stress? MutY genes could be assigned to metagenome-assembled genomes (MAGs), and thereby associate GO DNA repair with metabolic pathways that generate reactive oxygen, nitrogen and sulfur species. Our results indicate that cell-based life was under evolutionary pressure to cope with oxidized guanine well before O2 levels rose following the great oxidation event.

The chemistry and excitation of H2 and HD in the early Universe

ABSTRACT We have critically reviewed the literature pertaining to reactions that are significant for the chemistry of hydrogen-, deuterium-, and helium-bearing species in the homogeneous early Universe. For each reaction rate coefficient, we provide a fit in the modified-Arrhenius form, specifying the corresponding uncertainty and temperature range. This new network, limited to 21 reactions, should be the most reliable to date. Combined with accurate state-to-state rate coefficients for inelastic and reactive collisions involving H2 and HD, it allows us for the first time to follow the evolution of the abundances of atomic and molecular species, level populations of H2 and HD, and the ortho:para ratio (OPR) of H2, in a self-consistent fashion during the adiabatic expansion of the universe. The abundances of H2 and HD change only marginally compared to previous models, indicating that the uncertainties on the main reaction rate coefficients have essentially been removed. We also find that the adiabatic expansion has a dramatic effect on the OPR of H2, which freezes-out at redshifts z ≲ 50. In contrast, at higher redshifts, the populations of the rotational levels of H2 and HD are predicted to be fully thermalized at the temperature of the cosmic background radiation field, a result that conflicts with some recent, independent calculations. This new network allows the chemistry of primordial gas to be followed during the early phase of collapse towards Population III star progenitors.

Cyperus peptide SFRWQ inhibits oxidation and inflammation in RAW264.7 cell model

Oxidative stress can induce many diseases. Antioxidant peptides from food sources have the advantages of good safety, high activity, and good absorbability. In this study, a pentapeptide (SFRWQ; SER-PHE-ARG-TRP-GLN) was identified in a protein hydrolysate of Cyperus (Cyperus esculentus L.). Enzyme-linked immunosorbent assay (ELISA), real-time quantitative (qPCR), immunofluorescence and other techniques were used to evaluate the anti-inflammatory and antioxidant effects of SFRWQ. SFRWQ was found to have 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging ability, help increase superoxide dismutase (SOD) and catalase (CAT) levels in RAW264.7 cells, reduce reactive oxygen species (ROS) levels, and decrease tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) gene expression and secretion. The binding score of SFRWQ to recombinant Kelch-like ECH-associated protein 1 (Keap1) was greater than that of TX6. These findings suggest that SFRWQ activates the Keap1-Nrf2 cellular antioxidant signaling pathway. According to metabolomics studies, SFRWQ increased glutathione (GSH), glutathione disulfide (GSSG), and γ-glutamylcysteine levels and decreased the levels of Prostaglandin D2 (PGD2), Prostaglandin E2 (PGE2), and Prostaglandin H2 (PGH2), which are involved in arachidonic acid metabolism, to protect cells from LPS-induced damage. By elucidating the mechanism of action of SFRWQ, we provide a reference for the development of dietary antioxidant peptides.

Association of Serum Hydrogen Sulphide Levels and Dyslipidaemia: A Cross-sectional Study

Introduction: Dyslipidaemia is an important risk factor for coronary artery disease. Oxidative damage to plasma lipoproteins ultimately results in the development of atherosclerosis. Since Hydrogen Sulphide (H2 S) is a cytoprotective molecule in oxidative stress, decreased H2 S levels may be a cause of dyslipidaemia. Aim: To determine the relationship between the serum levels of H2 S with serum Triglycerides (TG), Total Cholesterol (TC), and High-density Lipoprotein Cholesterol (HDL-C) in cases of dyslipidaemia. Materials and Methods: A cross-sectional study was conducted between December 2022 and June 2023 in the Departments of Biochemistry and Medicine at KPC Medical College, Jadavpur, Kolkata, West Bengal, India. Serum lipid profile {TC, TGs, HDL-C, and Low-density Lipoprotein Cholesterol (LDL-C) (calculated by Friedewald’s equation)} and serum H2 S were measured in 70 cases of dyslipidaemia {according to National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) criteria} aged between 30 to 80 years and compared with an equal number of healthy volunteers as controls. The means of continuous variables were compared by independent t-tests and Mann-Whitney U tests. The Chi-square test was applied to compare gender distribution. Pearson’s and Spearman’s correlation coefficients were calculated for normal and non normal distributions, respectively. Results: The mean age of dyslipidaemic patients (54.54 years±11.19) was significantly (p=0.0017) higher than that of the controls (47.02 years±16.18). Among the 70 cases of dyslipidaemia, 38 participants were male and 32 were female, while among the healthy controls (n=70), 42 participants were male and 28 were female. The serum H2 S levels in cases of dyslipidaemia (37.91±6.28 μmol/L) were significantly lower than in the healthy controls (58.52±12.92, p&lt;0.01 μmol/L). A significant positive correlation was found between serum H2 S levels and HDL-cholesterol (r=0.81, p&lt;0.001), whereas a negative correlation was found between serum H2 S and TG levels (r=-0.55, p&lt;0.001). Conclusion: In the present study, dyslipidaemia was associated with decreased levels of serum H2 S. Serum H2 S was positively correlated with serum HDL and negatively correlated with serum TG levels.

A formally exact theory to construct nonreactive forcefields using linear regression to optimize bonded parameters.

This article derives theoretical foundations of force field functional theory (FFFT). FFFT studies topics related to the functional representation of nonreactive forcefields to achieve various desirable properties such as: (a) formal exactness of the forcefield's energy functional under certain conditions, (b) a formally exact ansatz separating the bonded potential energy from the nonbonded potential energy within a bonded cluster in a way that enables bonded parameters to be optimized using linear regression instead of requiring nonlinear regression, (c) the potential energy's continuous differentiability to various orders with respect to energetically accessible internal coordinate displacements within a subdomain defined by one electronic ground state, (d) forcefield design that guarantees the reference ground-state geometry is exactly reproduced as an equilibrium structure on the forcefield's potential energy landscape, (e) reasonably accurate and broadly applicable frugal model potentials, (f) computationally efficient embedded feature selection that identifies and removes unimportant forcefield terms, (g) well-designed methods to parameterize the forcefield from quantum-mechanically-computed and (optionally) experimental reference data, and (h) forcefields that approximately reproduce experimentally-measured properties. This article also introduces: (1) an angle-bending model potential that more accurately describes physical dynamics and is continuously differentiable to all orders with respect to internal coordinate displacements even when the bond angle is linear (i.e., θ = π (180°)) and (2) a first-principles-derived stretch potential that accurately describes short-range Pauli repulsion and the long-range bond dissociation energy. This new angle-bending potential gave good agreement to CCSD quantum-chemistry calculations for CaH2, CO2, H2O, HNO, Li2O, NO2, NS2, SF2, SiH2, and SO2 molecules. This new bond-stretch potential reproduced the first 12+ and 30+ vibrational energy levels of H2 and O2 molecules, respectively, within a few percent of experimental values. Studying the C-F bond stretch in C6F6 as an example, the new ansatz (item (b) above) reduced sensitivity of the optimized force constant's value to choice of nonbonded interaction parameters by an order of magnitude compared to the old ansatz. Normal mode analysis of optimized flexibility models for CO2, H2O, HNO, and SO2 molecules yielded vibrational transition frequencies within a few percent of experimental values. These results demonstrate advantages of this new approach.

Relaxation behavior of vibrationally excited N2(X1Σg + v″ = 6) collisions with H2

Relaxation behavior of vibrationally excited N2 (X1Σg + v″ = 6) induced by collisions with H2 has been investigated using coherent anti-Stokes Raman spectroscopy (CARS). The total pressure of the N2–H2 mixture was 500 Torr, and the molar ratios of H2 were 0.3, 0.4, 0.5, 0.6 and 0.8, respectively. The v″ = 6 vibrational state of the electronic ground-state manifold X1Σg + of N2 was selectively excited by overtone pumping, and the population evolution was monitored using CARS spectroscopy. The collisional deactivation rate coefficients of the excited state N2 (v″ = 6) with H2 and N2 are approximately 2.59 × 10−14 cm3s−1 and 1.04 × 10−14 cm3s−1 at 300 K, and 2.57 × 10−14 cm3s−1 and 0.54 × 10−14 cm3s−1 at 320 K, respectively. The relaxation rate coefficient of the N2–H2 collision was approximately 2.5 and 5 times that of the self-relaxation rate coefficient. The experimental results show that the population densities of the (1,2), (2,2), (3,5), and (3,6) levels of H2 have a maximum at 320 K, while the population densities of (2,3) and (2,4) show little change with increasing temperature. Simultaneously, the time-resolved CARS profiles of the vibrational levels v = 6,5,4 by preparing v = 6 of N2 also indicated that a near-resonant multi-quantum relaxation process occurred between N2–H2. The collision-induced population distribution of H2 was observed at molar ratios of 0.3, 0.4, 0.5, 0.6 and 0.8, respectively. The ro-vibrational population distribution of H2 after collision with N2 is given by the CARS signal intensity ratio, and the population of hydrogen molecules at v = 2, 3 vibrational states also provides strong experimental evidence for energy near-resonance collisions between N2–H2.

Collisional excitation of PO+ by para-H2: potential energy surface, scattering calculations, and astrophysical applications

ABSTRACT We report the derivation of rate coefficients for the rotational (de-)excitation of PO+ induced by collisions with H2. The calculations were performed on a 4D potential energy surface, obtained on top of highly accurate ab initio energy points. Preliminary tests pointed out the low influence of the coupling between j = 0 and the higher rotational levels of H2 on the cross-sections values, thus allowing to neglect the rotational structure of H2. On this basis, state-to-state collisional rate coefficients were derived for temperatures ranging from 5 to 200 K. Radiative transfer calculations have been used to model the recent observation of PO+ in the G+0.693–0.027 molecular cloud, in order to evaluate the possible impact of non-LTE models on the determination of its physical conditions. The derived column density was found to be approximately ∼ 3.7 × 1011 cm−2, which is 60% (a factor of ∼ 1.7) smaller than the previously LTE-derived value. Extensive simulations show that PO+ low-j rotational lines exhibit maser behaviour at densities between 104 and 106 cm−3, thus highlighting the importance of a proper treatment of the molecular collisions to accurately model PO+ emissions in the interstellar medium.

Enhancement of combustion performances and reduction of combustible species emission using an additional of combustion-reaction of engine

A new concept is presented to enhance the combustion performance and to reduce the combustible species gas emission of a combustion engine. Exhaust gases are still rich in typical combustible species whose chemical energy can be harvested to increase efficiency. The idea is to provide extra time to the combustion reactions by the addition of two-post-expansion-strokes to the Otto cycle. The chemical energy of the working-gas residual combustible species is converted into an additional heat-input. The new thermodynamic cycle, called the MUB-2 cycle, is similar to an Otto cycle but has two isochoric heat-inputs instead of one. The cycle has been experimentally tested and analytically evaluated. It is found that even though the engine’s thermal-conversion efficiency is not changed, however, the average values of combustion efficiency, fuel-conversion efficiency, heat-input per cycle, and indicated work per cycle are increased by 6.42 (%), while average levels of HC, CO, and H2 are reduced by 43.86 (%), 38.58 (%), and 38.58 (%), respectively. Other advantages of the MUB-2 cycle are higher heat input per cycle and more robustly work to the changes of air-fuel mixture homogeneity over the Otto cycle, the Atkinson-Miller cycle, and other cycles that only incorporate a single combustion process.

Oxidation of Hydrogen Sulfide to Polysulfide and Thiosulfate by a Carbon Nanozyme: Therapeutic Implications with an Emphasis on Down Syndrome.

Hydrogen sulfide (H2 S) is a noxious, potentially poisonous, but necessary gas produced from sulfur metabolism in humans. In Down Syndrome (DS), the production of H2 S is elevated and associated with degraded mitochondrial function. Therefore, removing H2 S from the body as a stable oxide could be an approach to reducing the deleterious effects of H2 S in DS. In this report we describe the catalytic oxidation of hydrogen sulfide (H2 S) to polysulfides (HS2+n - ) and thiosulfate (S2 O3 2- ) by poly(ethylene glycol) hydrophilic carbon clusters (PEG-HCCs) and poly(ethylene glycol) oxidized activated charcoal (PEG-OACs), examples of oxidized carbon nanozymes (OCNs). We show that OCNs oxidize H2 S to polysulfides and S2 O3 2- in a dose-dependent manner. The reaction is dependent on O2 and the presence of quinone groups on the OCNs. In DS donor lymphocytes we found that OCNs increased polysulfide production, proliferation, and afforded protection against additional toxic levels of H2 S compared to untreated DS lymphocytes. Finally, in Dp16 and Ts65DN murine models of DS, we found that OCNs restored osteoclast differentiation. This new action suggests potential facile translation into the clinic for conditions involving excess H2 S exemplified by DS.

Effect of fumaric acid in combination with Asparagopsis taxiformis or nitrate on in vitro gas production, pH, and redox potential

Reduction in enteric methane (CH4) emissions from cattle can be achieved through use of feed additives, which often results in increased emission of hydrogen (H2). The objective of this study was to investigate in vitro effects of a known hydrogen sink, fumaric acid, in combination with either of 2 methane inhibitors, the macroalga Asparagopsis taxiformis or nitrate, on CH4 and H2 production, feed degradability, pH, and redox potential. A corn silage (0.5 g; control) was incubated in buffered rumen fluid with the addition of 0.025 g of nitrate (Nit), 0.025 g of dried A. taxiformis (Asp), 0.025 g of nitrate + 0.025 g of fumaric acid (Nit+Fum), or 0.025 g of dried A. taxiformis + 0.025 g of fumaric acid (Asp+Fum). Accumulated gas production was determined using the AnkomRF system equipped with airtight gasbags. There were 9 replicates per treatment with 3 replicates per treatment stopped after 24, 36, and 48 h of incubation. The amount of undegraded feed was determined by filtration. Gas composition was determined by gas chromatography. Degradable dry matter, degradable organic matter, pH, redox potential, and gas production data were analyzed using a mixed model. Asp and Asp+Fum reduced CH4 production by 98% or greater at all incubation times, whereas Nit and Nit+Fum reduced CH4 production (mL of CH4/g of dry matter) by 52% to 63% compared with the control. Hydrogen was only detectable in gas from Asp and Asp+Fum treatments, with no difference in H2 production between the 2 treatments. The treatments had only minor effects on redox potential in the fermented rumen fluid, and pH was lowest for treatments including A. taxiformis. In conclusion, both A. taxiformis and nitrate reduced CH4 production. Fumaric acid in combination with A. taxiformis did not reduce H2 production, and treatments including nitrate did not result in any detectable levels of H2. Future dose-response in vitro studies will contribute to investigating the potential of fumaric acid as a hydrogen sink during CH4 mitigation.

Enrichment of rare methanogenic Archaea shows their important ecological role in natural high-CO2 terrestrial subsurface environments.

Long-term stability of underground CO2 storage is partially affected by microbial activity but our knowledge of these effects is limited, mainly due to a lack of sites. A consistently high flux of mantle-derived CO2 makes the Eger Rift in the Czech Republic a natural analogue to underground CO2 storage. The Eger Rift is a seismically active region and H2 is produced abiotically during earthquakes, providing energy to indigenous microbial communities. To investigate the response of a microbial ecosystem to high levels of CO2 and H2, we enriched microorganisms from samples from a 239.5 m long drill core from the Eger Rift. Microbial abundance, diversity and community structure were assessed using qPCR and 16S rRNA gene sequencing. Enrichment cultures were set up with minimal mineral media and H2/CO2 headspace to simulate a seismically active period with elevated H2. Methane headspace concentrations in the enrichments indicated that active methanogens were almost exclusively restricted to enrichment cultures from Miocene lacustrine deposits (50-60 m), for which we observed the most significant growth. Taxonomic assessment showed microbial communities in these enrichments to be less diverse than those with little or no growth. Active enrichments were especially abundant in methanogens of the taxa Methanobacterium and Methanosphaerula. Concurrent to the emergence of methanogenic archaea, we also observed sulfate reducers with the metabolic ability to utilize H2 and CO2, specifically the genus Desulfosporosinus, which were able to outcompete methanogens in several enrichments. Low microbial abundance and a diverse non-CO2 driven microbial community, similar to that in drill core samples, also reflect the inactivity in these cultures. Significant growth of sulfate reducing and methanogenic microbial taxa, which make up only a small fraction of the total microbial community, emphasize the need to account for rare biosphere taxa when assessing the metabolic potential of microbial subsurface populations. The observation that CO2 and H2-utilizing microorganisms could only be enriched from a narrow depth interval suggests that factors such as sediment heterogeneity may also be important. This study provides new insight on subsurface microbes under the influence of high CO2 concentrations, similar to those found in CCS sites.

Structural basis for bacterial energy extraction from atmospheric hydrogen

Diverse aerobic bacteria use atmospheric H2 as an energy source for growth and survival1. This globally significant process regulates the composition of the atmosphere, enhances soil biodiversity and drives primary production in extreme environments2,3. Atmospheric H2 oxidation is attributed to uncharacterized members of the [NiFe] hydrogenase superfamily4,5. However, it remains unresolved how these enzymes overcome the extraordinary catalytic challenge of oxidizing picomolar levels of H2 amid ambient levels of the catalytic poison O2 and how the derived electrons are transferred to the respiratory chain1. Here we determined the cryo-electron microscopy structure of the Mycobacterium smegmatis hydrogenase Huc and investigated its mechanism. Huc is a highly efficient oxygen-insensitive enzyme that couples oxidation of atmospheric H2 to the hydrogenation of the respiratory electron carrier menaquinone. Huc uses narrow hydrophobic gas channels to selectively bind atmospheric H2 at the expense of O2, and 3 [3Fe–4S] clusters modulate the properties of the enzyme so that atmospheric H2 oxidation is energetically feasible. The Huc catalytic subunits form an octameric 833 kDa complex around a membrane-associated stalk, which transports and reduces menaquinone 94 Å from the membrane. These findings provide a mechanistic basis for the biogeochemically and ecologically important process of atmospheric H2 oxidation, uncover a mode of energy coupling dependent on long-range quinone transport, and pave the way for the development of catalysts that oxidize H2 in ambient air.

The role of the H2 S / cystathionine-γ-lyase system in the mechanisms of cardioprotective action of vitamin D in diet-induced obesity

Obesity and vitamin D deficiency are risk factors for cardiovascular disease that are often coexisting. The identification of new biochemical factors that may modify the cardiovascular effects of vitamin D in obesity remains relevant. The aim of study: to estimate the role of the H2 S / cystathionine-γ-lyase system in the mechanisms of cardioprotective effect of vitamin D in diet-in-duced obesity. Methods. The experiments were carried out on 40 white male laboratory rats in accordance with the principles of bioethics (Directive 2010/63/EU). The active form of vitamin D – 1,25(OH)2 D3 was administered to animals with a model of diet-induced obesity (DIO) for 2 weeks. Propargylglycine and NaHS were used to modulate the state of the H 2 S / cystathionine-γ-lyase system. Levels of H2 S, caspase-3, TNFα, HSP60, HSP70, and oxidative stress markers were determined in myocardial and thoracic aortic homogenates. Results. The administration of 1,25(OH)D 3 reduced biochemical disorders in myocardium and aorta in DIO: H 2 S content and cystathionine-γ-lyase activity increased, levels of inflammatory and apoptotic mediators (caspase-3, TNFα) decreased, HSP60 and HSP70 levels normalized, and signs of oxidative stress decreased. The cardioprotective effects of 1,25(OH)D 3 were significantly reduced by inhibition of H2 S synthesis, while the H 2 S donor (NaHS) enhanced these effects. Conclusions. In obesity, modulation of H 2 S / cystathionine-γ-lyase activity affects the cardioprotective effects of vitamin D, which are realized through the signaling pathways of inflammation, apoptosis and oxidative stress

Comparative variability studies for yield and fibre quality traits in F2 generations derived from single and double crosses in cotton (Gossypium hirsutum L)

Developing cotton cultivars with high yield and superior fibre quality is a major goal of any cotton breeding program. The present study emphasized on estimating and comparing genetic variability parameters in F2 generations derived from two double crosses and their four single crosses to isolate segregants with superior yield and fibre quality. Higher PCV and GCV (&gt;20) with higher magnitude of variation were noticed for seed cotton yield per plant in single and double crosses but the magnitude of variability was found low in double crosses compared to single crosses indicating a higher degree of variability can be obtained in single crosses. Moderate to low PCV and GCV were found for GOT and LI. The moderate to high h2 (&gt;60 %) with high GAM was noticed in double and single crosses for seed cotton yield per plant. For GOT and LI, moderate heritability (30-60 %) was noticed for single crosses while it was high for their double cross indicating that the population derived from the double cross has a higher ability to transmit the traits to its progenies. Except for micronaire values, the fibre quality traits recorded low to moderate levels of PCV, GCV, h2, and GAM in single and double crosses indicating that achieving the desired level of genetic improvement for them would be a painstaking effort in early segregating generations. However, selecting lines from these crosses for superior fibre quality will be rewarding in later advanced generations.

RETROSPECTIVE REVIEW OF ORAL FOOD CHALLENGE OUTCOMES IN A MILITARY MEDICAL CENTER

<h3>Introduction</h3> Oral food challenges (OFCs) are the gold standard for diagnosis of food allergies. Limited data exists comparing OFCs across adult and pediatric subgroups in the military's health care system. The purpose of this study is to identify clinical and laboratory predictors of negative OFCs in one military medical center. <h3>Methods</h3> A retrospective chart review was performed on all open OFCs between June 2014 and June 2021 at a military tertiary center allergy clinic. <h3>Results</h3> 652 patients who underwent 1,112 OFCs were included with 910 negative total OFCs (81.8%). A total of 615 pediatric (82.0%) and 294 of adult (81.4%) passed their OFCs. Successful OFCs were highest among almond (94.4%), shrimp (94.2%), crab (91.9%), and egg (88.9%) and lowest among cashew (62.0%), walnut (63.5%), pistachio (69.7%), and pecan (71.2%). There was statistical significance in outcomes when analyzing sIgE (P <0.001), SPT wheal size (P <0.001), and history of a prior failed challenge (p=0.042). Walnut OFCs demonstrated an outcome difference between age groups (P= 0.008) – pediatrics subgroup with a higher pass rate (74.4%) compared to adults (40.0%). Higher levels of Ara h2 were also associated with a greater number of failed challenges (p= 0.045). <h3>Conclusion</h3> For OFCs performed in a military medical center which can influence career decisions, sIgE is a reliable lab marker in risk stratification of outcomes. Higher Ara h 2 was associated with failed OFCs. A significant difference in pass rate was noted between pediatric and adult populations for certain foods.