Total Hydrogen Gas Research Articles

Exploring Neutral Hydrogen in Radio MOlecular Hydrogen Emission Galaxies (MOHEGs) and Prospects with the SKA

Empirical studies of cold gas content are essential for comprehending the star formation activities and evolution in galaxies. However, it is not straightforward to understand these processes because they depend on various physical properties of the interstellar medium. Massive Faranoff–Riley I/II type radio galaxies rich in molecular hydrogen with lower star formation activities are known as radio molecular hydrogen emission galaxies (MOHEGs). We present a study of neutral hydrogen-gas-associated radio MOHEGs at redshifts <0.2 probed via the H i 21 cm absorption line. Neutral hydrogen is detected in 70% of these galaxies, which are located at a distance of 8–120 kpc from the neighboring galaxies. These galaxies show a scarcity of H i gas as compared to merging galaxies at similar redshifts. We found no strong correlation between N(H i), NH, and the galaxy properties, regardless of whether the H i is assumed to be cold or warm, indicating that the atomic gas probably plays no important role in star formation. The relation between the total hydrogen gas surface density and the star formation surface density deviates from the standard Kennicutt–Schmidt law. Our study highlights the importance of H i studies and offers insights into the role of atomic and molecular hydrogen gas in explaining the properties of these galaxies. In the upcoming H i 21 cm absorption surveys with next-generation radio telescopes such as the Square Kilometre Array and pathfinder instruments, it may be possible to provide better constraints for these correlations.

In vitro fermentation properties of magnesium hydride and related modulation effects on broiler cecal microbiome and metabolome.

Magnesium hydride (MGH), a highly promising hydrogen-producing substance/additive for hydrogen production through its hydrolysis reaction, has the potential to enhance broiler production. However, before incorporating MGH as a hydrogen-producing additive in broiler feed, it is crucial to fully understand its impact on microbiota and metabolites. In vitro fermentation models provide a fast, reproducible, and direct assessment tool for microbiota metabolism and composition. This study aims to investigate the effects of MGH and coated-magnesium hydride (CMG) on fermentation characteristics, as well as the microbiota and metabolome in the culture of in vitro fermentation using cecal inocula from broilers. After 48 h of incubation, it was observed that the presence of MGH had a significant impact on various factors. Specifically, the content of N-NH3 decreased, while the total hydrogen gas and total SCFAs increased. Furthermore, the presence of MGH promoted the abundance of SCFA-producing bacteria such as Ruminococcus, Blautia, Coprobacillus, and Dysgonomonas. On the other hand, the presence of CMG led to an increase in the concentration of lactic acid, acetic acid, and valeric acid. Additionally, CMG affected the diversity of microbiota in the culture, resulting in an enrichment of the relative abundance of Firmicutes, as well as genera of Lactobacillus, Coprococcus, and Eubacterium. Conversely, the relative abundance of the phylum Proteobacteria and pathogenic bacteria Shigella decreased. Metabolome analysis revealed that MGH and CMG treatment caused significant changes in 21 co-regulated metabolites, primarily associated with lipid, amino acid, benzenoids, and organooxygen compounds. Importantly, joint correlation analysis revealed that MGH or CMG treatments had a direct impact on the microbiota, which in turn indirectly influenced metabolites in the culture. In summary, the results of this study suggested that both MGH and coated-MGH have similar yet distinct positive effects on the microbiota and metabolites of the broiler cecal in an in vitro fermentation model.

Development of a Model System for Gas Cavity Formation Behavior of Magnesium Alloy Implantation.

Clinical applications of magnesium (Mg)-based screws have reported gas cavity formation in the surrounding tissue, which sometimes delays the fixation of the bone fracture. The gas cavity formation is considered to depend on the balance between hydrogen generation by Mg corrosion reacting with water in the body fluid and its diffusion into the surrounding tissue by capillary flow. In order to understand the gas cavity formation behavior by Mg-based material implantation, we developed a new in vitro model system to recreate this cavity formation phenomenon: the hydrogen generation by corrosion and its diffusion into the medium. A model tissue is prepared by gelation of the cell culture medium in a sterile condition. The immersion of Mg alloy samples was performed under 5% CO2 atmosphere with periodic observation by X-ray computed tomography, which enabled us to observe gas cavity growth up to 28 d. For demonstrating the usefulness of our model system, Mg alloy samples with different corrosion rates were prepared by a biodegradable polymer coating. AZ31 screws were spin-coated by poly-l-lactide (PLLA) and classified into three groups by their coating thickness as 1.0 ± 0.0, 1.6 ± 0.2, and 2.0 ± 0.1 μm (ave. ± s.d.). Upon their immersion into the model tissue, the gas cavity volumes formed were 1.57 ± 0.23, 1.06 ± 0.22, and 0.38 ± 0.09 mm3/mm2 for 1.0, 1.6, and 2.0 μm coating samples, having the weight loss of 20.2 ± 2.93, 18.5 ± 2.84, and 11.3 ± 3.54 μg/mm2, respectively (ave. ± s.d.). This result clearly indicates the dependence of gas cavity formation on the corrosion rate of the sample. The gas cavity volume was only 3.3∼7.5% of the total hydrogen gas volume estimated based on the weight loss of the samples at 28 d, which is in the range of those calculated from the clinical report (3.2∼9.4% at 4w). This system can be an effective tool to investigate the gas cavity formation behavior and contribute to understand the mechanisms and controlling factors of this phenomenon.

H i-to-H2 Transitions in Dust-free Interstellar Gas

Abstract We present numerical computations and analysis of atomic-to-molecular (H i-to-H2) transitions in cool (∼100 K), low-metallicity, dust-free (primordial) gas in which molecule formation occurs via cosmic-ray-driven negative ion chemistry and removal is by a combination of far-UV photodissociation and cosmic-ray ionization and dissociation. For any gas temperature, the behavior depends on the ratio of the Lyman–Werner (LW) band FUV intensity to gas density, I LW/n, and the ratio of the cosmic-ray ionization rate to the gas density, ζ/n. We present sets of H i-to-H2 abundance profiles for a wide range of ζ/n and I LW/n for dust-free gas. We determine the conditions for which H2 absorption-line self-shielding in optically thick clouds enables a transition from atomic to molecular form for ionization-driven chemistry. We also examine the effects of cosmic-ray energy losses on the atomic and molecular density profiles and transition points. For a unit Galactic interstellar FUV field intensity (I LW = 1) with LW flux 2.07 × 107 photons cm−2 s−1 and a uniform cosmic-ray ionization rate ζ = 10−16 s−1, an H i-to-H2 transition occurs at a total hydrogen gas column density of 4 × 1021 cm−2, within 3 × 107 yr, for a gas volume density of n = 106 cm−3 at 100 K. For these parameters, the dust-free limit is reached for a dust-to-gas ratio Z d ′ ≲ 10 − 5 , which may be reached for overall metallicities Z ′ ≲ 0.01 relative to Galactic solar values.

Hydrogen gas production is associated with reduced interleukin-1β mRNA in peripheral blood after a single dose of acarbose in Japanese type 2 diabetic patients

Acarbose, an α-glucosidase inhibitor, leads to the production of hydrogen gas, which reduces oxidative stress. In this study, we examined the effects of a single dose of acarbose immediately before a test meal on postprandial hydrogen gas in breath and peripheral blood interleukin (IL)-1β mRNA expression in Japanese type 2 diabetic patients. Sixteen Japanese patients (14 men, 2 women) participated in this study. The mean±standard deviation age, hemoglobin A1c and body mass index were 52.1±15.4 years, 10.2±2.0%, and 27.7±8.0kg/m2, respectively. The patients were admitted into our hospital for 2 days and underwent test meals at breakfast without (day 1) or with acarbose (day 2). We performed continuous glucose monitoring and measured hydrogen gas levels in breath, and peripheral blood IL-1β mRNA levels before (0min) and after the test meal (hydrogen gas: 60, 120, 180, and 300min; IL-1β: 180min). The induction of hydrogen gas production and the reduction in peripheral blood IL-1β mRNA after the test meal were not significant between days 1 (without acarbose) and 2 (with acarbose). However, the changes in total hydrogen gas production from day 1 to day 2 were closely and inversely associated with the changes in peripheral blood IL-1β mRNA levels. Our results suggest that an increase in hydrogen gas production is inversely associated with a reduction of the peripheral blood IL-1β mRNA level after a single dose of acarbose in Japanese type 2 diabetic patients.

Effects of pyrolysis parameters on hydrogen formations from biomass: a review

This study investigates the effects of different parameters such as biomass composition, moisture content, particle size, heating rate, temperature, inert gas, reactor system, and catalyst on the production of hydrogen gas (HG) and other gases (OGs) such as CO2, CO, CH4, C2H6, and so on. The reformation of OGs into H2 via the shift reaction significantly increases the total HG formation during biomass pyrolysis. Biomass raw material is capable of producing different proportions of HG at different temperatures because the raw material structure varies from one material to another. It is very puzzling that the formation of HG and total gas (TG) could either increase or decrease with moisture and this result varied between researchers. Smaller particles are more suitable than larger ones in terms of HG and TG formation. Additionally, longer residence times and higher temperatures favor good HG yield while the heating rate is a function of heat flux and particle size of biomass fuel is supposed to increase the pyrolytic gases and properties. Moreover, the heating rate would play a smaller role on the process when the system is introduced with inert gas and if the purpose is to maximize the production of TGs, secondary reactions such as thermal cracking, re-polymerization, and re-condensation should be maximized because the inert gas removes the volatiles from the pyrolysis environment. Therefore, the ultimate product of biomass conversion is dependent on the reactor design and type of feedstock in the presence of appropriate catalysts.

Applying a one-dimensional PDR model to the Taurus molecular cloud and its atomic envelope

In this contribution, we test our previously published one-dimensional PDR model for deriving total hydrogen volume densities from HI column density measurements in extragalactic regions by applying it to the Taurus molecular cloud, where its predictions can be compared to available data. Also, we make the first direct detailed comparison of our model to CO(1-0) and far-infrared emission. Using an incident UV flux G0 of 4.25 ({\chi} = 5) throughout the main body of the cloud, we derive total hydrogen volume densities of \approx 430 cm-3, consistent with the extensive literature available on Taurus. The distribution of the volume densities shows a log-normal shape with a hint of a power-law shape on the high density end. We convert our volume densities to H2 column densities assuming a cloud depth of 5 parsec and compare these column densities to observed CO emission. We find a slope equivalent to a CO conversion factor relation that is on the low end of reported values for this factor in the literature (0.9 x 1020 cm-2 (K km s-1)-1), although this value is directly proportional to our assumed value of G0 as well as the cloud depth. We seem to under-predict the total hydrogen gas as compared to 100 {\mu}m dust emission, which we speculate may be caused by a higher actual G0 incident on the Taurus cloud than is generally assumed.

Hydrogen gas production of broiler chicks in response to soybean meal and alpha-galactoside free, ethanol-extracted soybean meal

In order to measure broiler chick hydrogen gas production, a sealed atmosphere chamber was constructed and chicks were intubated with soybean meal (SBM), alpha-galactoside free, ethanol-extracted soybean meal (ESBM), and ESBM with alpha-galactosides added to the levels of SBM (ESBMG). Six male broiler chicks averaging 156 g of weight were deprived of feed for 12 h prior to intubation with 6 g of the test soybean meals. Two chicks were used for each treatment. Following intubation, chicks were placed in the sealed atmosphere chamber for 20 min at 2-h intervals for 28 h. At the end of this 20-min period, a sample of the chamber atmosphere was collected with a gas-tight syringe and analyzed for hydrogen gas by gas-solid chromatography. The hydrogen production of the two chicks intubated with SBM peaked 7 h postintubation at 127 ppm. The ESBM produced a peak at approximately 17 h postintubation at 26 ppm. Intubation with ESBMG resulted in peak hydrogen production at approximately 12 h postintubation at an average of 67 ppm. Results indicate that chicks intubated with SBM produced 3.2 times the amount of total hydrogen gas than those chicks intubated with ESBM. Chicks intubated with ESBMG produced 2.2 times the amount of total hydrogen gas than chicks intubated with ESBM. The research indicates the alpha-galactoside oligosaccharides are a major cause of hydrogen gas production from SBM in poultry.

Infrared Spectroscopy of NGC 4151:Infrared Space ObservatoryObservations and Narrow Emission Line Region Line Profiles

We present Infrared Space Observatory (ISO) Short-Wavelength Spectrometer (SWS) and ISOPHOT-S spectroscopy of the Seyfert galaxy NGC 4151. We detect a total of 17 fine-structure emission lines emitted by a wide range of low- and high-excitation ions, two rotational lines of molecular hydrogen, and the Brβ H I line. We find that the mid-IR fine-structure line profiles display blue asymmetries that are very similar to those observed in the optical lines produced in the narrow-line region. Because the mid-infrared lines are much less sensitive to extinction than the optical lines, this similarity places strong constraints on scenarios that have been invoked to explain the optical line asymmetries. For example, we are able to rule out the simplest radial motion plus dust scenarios for the production of the line asymmetries. Our preferred model is of a central, geometrically thin but optically thick, obscuring screen of subarcsecond extension, enclosing a total hydrogen gas mass of 5×106 M☉. This mass may be molecular. The weakness of polycyclic aromatic hydrocarbon (PAH) emission features in the low-resolution spectrum is evidence that star formation plays a minor role in the circumnuclear region of NGC 4151. In a companion paper, we use the rich set of mid-infrared lines to determine the obscured photoionizing continuum produced by the active galactic nucleus.

Energy expenditure and net substrate utilization in men ingesting usual and high amounts of nonstarch polysaccharide

BackgroundDiets intrinsically high in nonstarch polysaccharides (NSPs) are frequently advised for body weight regulation and health, but the consequences for energy expenditure and fuel selection are undetermined. ObjectiveWe determined whether energy expenditure and fuel selection differ when men consume a diet intrinsically higher in NSP than a usual mixed diet. DesignA randomized crossover design was used in which 12 healthy men were fed a maintenance diet for <3 wk in a metabolic suite. By judicial choice of food exchanges, the usual- and high NSP diets were similar in protein, fat, and carbohydrate contents. Twenty-four–hour, indirect, open-circuit calorimetry was performed, including measurements of total hydrogen gas and methane. Participants were weight stable (within 2 kg for 3 wk), entered an 11-m3 calorimetry chamber for 36 h with measurements taken in the last 24 h, and underwent a strictly controlled program of moderate physical activity (1.3 × basal metabolic rate). ResultsThe mean total 24-h energy expenditure and percentages from protein, fat, and carbohydrate metabolism were 10 MJ/d and 16%, 35%, and 48%, respectively. Differences (mean ± SEM) between the 2 diets were only –0.005 ± 0.130 MJ/d, –0.3 ± 1.3%, –0.2 ± 2.0%, and 0.6 ± 2.2%, respectively, and were nonsignificant (P > 0.2). ConclusionsThere was no thermogenic response to the high NSP diet, which would be advantageous for body weight control, and no short-term influence on body composition, as may be judged from a lack of change in protein, fat, or carbohydrate metabolism.

THE RADIOLYSIS OF SATURATED HYDROCARBONS

The yields of primary products in the radiolysis of some twenty saturated hydrocarbons (C5-C10) were measured. For all paraffins investigated, the yield of molecular'' hydrogen gas is approximately a constant fraction of the total hydrogen gas (0.40) despite changes in hydrocarbon structure and total hydrogen gas yield. Evidence is presented which indicates that this molecular'' hydrogen arises by a hot'' hydrogen atom mechanism rather than by a molecular detachment process. The balance of the hydrogen gas formed arises from the reaction of radiolytically produced chemical hydrogen atoms with the solvent. Congruent molecular'' unsaturation (olefins of the same carbon number produced in the presence of alkyl radical scavengers) ranges from 50 to 80% of the molecular'' hydrogen yield. Radicals produced by C-C bond scission interact within the cage of formation by disproportionation or recombination, or may escape from the cage to react with other radicals or solutes. Yields of such freely diffusing radicals were measured, and a definite relation to chemical structure was found. The results for all hydrocarbons studied are in complete agreement with the mechanism previously postulated for saturated hydrocarbon radiolysis. Determinations of free radical yields by e.p.r. give results in good agreement with other methods.