Carbon dioxide gas endoscopy of the deep gluteal space.
Ontology highlight
ABSTRACT:
SUBMITTER: Martin HD
PROVIDER: S-EPMC7549929 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description: Not available
| S-EPMC7339795 | biostudies-literature
Project description:Natural gas is considered the cleanest and recently the most abundant fossil fuel source, yet when it is extracted from wells, it often contains 10-20 mol% carbon dioxide (20-40 wt%), which is generally vented to the atmosphere. Efforts are underway to contain this carbon dioxide at the well-head using inexpensive and non-corrosive methods. Here we report nucleophilic porous carbons are synthesized from simple and inexpensive carbon-sulphur and carbon-nitrogen precursors. Infrared, Raman and (13)C nuclear magnetic resonance signatures substantiate carbon dioxide fixation by polymerization in the carbon channels to form poly(CO2) under much lower pressures than previously required. This growing chemisorbed sulphur- or nitrogen-atom-initiated poly(CO2) chain further displaces physisorbed hydrocarbon, providing a continuous carbon dioxide selectivity. Once returned to ambient conditions, the poly(CO2) spontaneously depolymerizes, leading to a sorbent that can be easily regenerated without the thermal energy input that is required for traditional sorbents.
| S-EPMC5603724 | biostudies-literature
Project description:To reveal the kinetic performance of gas molecules in hydrate growth, hydrate formation from pure CO2, flue gas, and biogas was measured using in-situ Raman and macroscopic methods at 271.6 K. In the in-situ Raman measurements, Raman peaks of gases in the hydrate phase were characterised and normalised by taking the water bands from 2800 to 3800 cm-1 as a reference, whose line shapes were not found to have a noticeable change in the conversion from Ih ice to sI hydrate. The hydrate growth was suggested to start with the formation of unsaturated hydrate nuclei followed by gas adsorption. In hydrate formed from all tested gases, CO2 concentrations in hydrate nuclei were found to be 23-33% of the saturation state. In the flue gas system, the N2 concentration reached a saturation state once hydrate nuclei formed. In the biogas system, competitive adsorption of CH4 and CO2 molecules was observed, while N2 molecules hardly evolved in hydrate formation. Combined with micro- and macroscopic analysis, small molecules such as N2 and CO2 were suggested to be more active in the formation of hydrate nuclei, and the preferential adsorption of CO2 molecules took place in the subsequent gas adsorption process.
| S-EPMC8080785 | biostudies-literature
Project description:Current technologies for production of natural gas hydrates (NGH), which include thermal stimulation, depressurization and inhibitor injection, have raised concerns over unintended consequences. The possibility of catastrophic slope failure and marine ecosystem damage remain serious challenges to safe NGH production. As a potential approach, this paper presents air-driven NGH recovery from permeable marine sediments induced by simultaneous mechanisms for methane liberation (NGH decomposition) and CH?-air or CH?-CO?/air replacement. Air is diffused into and penetrates NGH and, on its surface, forms a boundary between the gas and solid phases. Then spontaneous melting proceeds until the chemical potentials become equal in both phases as NGH depletion continues and self-regulated CH4-air replacement occurs over an arbitrary point. We observed the existence of critical methane concentration forming the boundary between decomposition and replacement mechanisms in the NGH reservoirs. Furthermore, when CO? was added, we observed a very strong, stable, self-regulating process of exchange (CH? replaced by CO?/air; hereafter CH?-CO?/air) occurring in the NGH. The proposed process will work well for most global gas hydrate reservoirs, regardless of the injection conditions or geothermal gradient.
| S-EPMC4196106 | biostudies-literature
Project description:Large amounts of CH4 in the form of solid hydrates are stored on continental margins and in permafrost regions. If these CH4 hydrates could be converted into CO2 hydrates, they would serve double duty as CH4 sources and CO2 storage sites. We explore here the swapping phenomenon occurring in structure I (sI) and structure II (sII) CH4 hydrate deposits through spectroscopic analyses and its potential application to CO2 sequestration at the preliminary phase. The present 85% CH4 recovery rate in sI CH4 hydrate achieved by the direct use of binary N2+CO2 guests is surprising when compared with the rate of 64% for a pure CO2 guest attained in the previous approach. The direct use of a mixture of N2+CO2 eliminates the requirement of a CO2 separation/purification process. In addition, the simultaneously occurring dual mechanism of CO2 sequestration and CH4 recovery is expected to provide the physicochemical background required for developing a promising large-scale approach with economic feasibility. In the case of sII CH4 hydrates, we observe a spontaneous structure transition of sII to sI during the replacement and a cage-specific distribution of guest molecules. A significant change of the lattice dimension caused by structure transformation induces a relative number of small cage sites to reduce, resulting in the considerable increase of CH4 recovery rate. The mutually interactive pattern of targeted guest-cage conjugates possesses important implications for the diverse hydrate-based inclusion phenomena as illustrated in the swapping process between CO2 stream and complex CH4 hydrate structure.
| S-EPMC1568911 | biostudies-literature
Project description:For the capture of CO(2) from mixed gas streams, materials for increased gas exchange are necessary. Efficient gas exchange systems already exist in the form of vascularized lung-tissue. Herein we report a fabrication technique for the synthesis of three-dimensional microvascular gas exchange units capable of removing CO(2) from flowing gas created using the recently reported Vaporization of a Sacrificial Component (VaSC) technique. We demonstrate the spatiotemporal pattern of CO(2) reactivity in the microvascular gas exchange unit using colorimetric, pH sensitive dyes. Control over three-dimensional placement of channels is shown to increase capture efficiencies. A computational finite element model validates and explains the experimental observations.
| S-EPMC10642706 | biostudies-literature
Project description:Activity reductions in early 2020 due to the coronavirus disease 2019 pandemic led to unprecedented decreases in carbon dioxide (CO2) emissions. Despite their record size, the resulting atmospheric signals are smaller than and obscured by climate variability in atmospheric transport and biospheric fluxes, notably that related to the 2019–2020 Indian Ocean Dipole. Monitoring CO2 anomalies and distinguishing human and climatic causes thus remain a new frontier in Earth system science. We show that the impact of short-term regional changes in fossil fuel emissions on CO2 concentrations was observable from space. Starting in February and continuing through May, column CO2 over many of the world’s largest emitting regions was 0.14 to 0.62 parts per million less than expected in a pandemic-free scenario, consistent with reductions of 3 to 13% in annual global emissions. Current spaceborne technologies are therefore approaching levels of accuracy and precision needed to support climate mitigation strategies with future missions expected to meet those needs.
| S-EPMC8565902 | biostudies-literature
Project description:Electroreduction of carbon dioxide (CO2) over copper-based catalysts provides an attractive approach for sustainable fuel production. While efforts are focused on developing catalytic materials, it is also critical to understand and control the microenvironment around catalytic sites, which can mediate the transport of reaction species and influence reaction pathways. Here, we show that a hydrophobic microenvironment can significantly enhance CO2 gas-diffusion electrolysis. For proof-of-concept, we use commercial copper nanoparticles and disperse hydrophobic polytetrafluoroethylene (PTFE) nanoparticles inside the catalyst layer. Consequently, the PTFE-added electrode achieves a greatly improved activity and Faradaic efficiency for CO2 reduction, with a partial current density >250 mA cm-2 and a single-pass conversion of 14% at moderate potentials, which are around twice that of a regular electrode without added PTFE. The improvement is attributed to a balanced gas/liquid microenvironment that reduces the diffusion layer thickness, accelerates CO2 mass transport, and increases CO2 local concentration for the electrolysis.
| S-EPMC7794506 | biostudies-literature
Project description:In a gas membrane, gas is transferred between a liquid and a gas through a microporous membrane. The main challenge is to achieve a high gas transfer while preventing wetting and clogging. With respect to the oxygenation of blood, haemocompatibility is also required. Here we coat macroporous meshes with a superamphiphobic-or liquid repellent-layer to meet this challenge. The superamphiphobic layer consists of a fractal-like network of fluorinated silicon oxide nanospheres; gas trapped between the nanospheres keeps the liquid from contacting the wall of the membrane. We demonstrate the capabilities of the membrane by capturing carbon dioxide gas into a basic aqueous solution and in addition use it to oxygenate blood. Usually, blood tends to clog membranes because of the abundance of blood cells, platelets, proteins and lipids. We show that human blood stored in a superamphiphobic well for 24?h can be poured off without leaving cells or adsorbed protein behind.
| S-EPMC3791477 | biostudies-literature
Project description:Transition metals are important in various industrial applications including catalysis. Due to the current concentration of CO2 in the atmosphere, various ways for its capture and utilization are investigated. Here, we study the activation of CO2 and H2O at [NbO3]- in the gas phase using a combination of infrared multiple photon dissociation spectroscopy and density functional theory calculations. In the experiments, Fourier-transform ion cyclotron resonance mass spectrometry is combined with tunable IR laser light provided by the intracavity free-electron laser FELICE or optical parametric oscillator-based table-top laser systems. We present spectra of [NbO3]-, [NbO2(OH)2]-, [NbO2(OH)2]-(H2O) and [NbO(OH)2(CO3)]- in the 240-4000 cm-1 range. The measured spectra and observed dissociation channels together with quantum chemical calculations confirm that upon interaction with a water molecule, [NbO3]- is transformed to [NbO2(OH)2]- via a barrierless reaction. Reaction of this product with CO2 leads to [NbO(OH)2(CO3)]- with the formation of a [CO3] moiety.
| S-EPMC10123662 | biostudies-literature