Gas Charge Research Articles

The analytical method for the specification of the beginning of hydrating in the offshore gas main pipelines

The paper is dedicated to the analysis of hydrating conditions in the process of the transportation of the natural gas by subsea pipeline, to the mechanism of formation of hydrate plugs, to the localization and elimination by means of an immediate definition of hydrates as well. As a result of the analysis, it was marked that one of the complicated issues in the transportation of the natural gas, particularly via the sea, is the hydrating. Gas hydrates are crystal compounds formed from the water and gas in the specific temperature and pressure parameters. The necessity of the implementation of such a complicated and labor-intensive process as the weighting and separation of hydrates from the subsea gas pipelines as a result of hydrating is noted. According to the results of the observation of subsea gas pipelines, it was specified that the hydrates and partial or full choking of gas pipeline occur due to two various scenarios. The first case arises from the deposition of the hydrate in the inner surface of gas pipeline, and the second one – from the accumulation of a great deal of water and condensate within the pipeline, as well as from the decrease of pipeline flow in the section of fluid collection, from the increase of gas charge and its temperature. Unlike the onshore gas pipelines, the number of technological parameters for an accurate estimation of the moment of hydrating in the offshore gas pipelines is quite limited. The paper presents an analytical method for the specification of the hydrating moment within a subsea gas main in the limited parameters. The reports on an actual gas pipeline justified the efficiency and information value of the method. Suggested method is characterized with the simplicity, perspective of an immediate employment and comfort of usage by the staff.

Discovery of High-Performing Metal-Organic Frameworks for On-Board Methane Storage and Delivery via LNG-ANG Coupling: High-Throughput Screening, Machine Learning, and Experimental Validation.

Liquefied natural gas (LNG) gasification coupled with adsorbed natural gas (ANG) charging (LNG–ANG coupling) is an emerging strategy for efficient delivery of natural gas. However, the potential of LNG–ANG to attain the advanced research projects agency‐energy (ARPA‐E) target for onboard methane storage has not been fully investigated. In this work, large‐scale computational screening is performed for 5446 metal–organic frameworks (MOFs), and over 193 MOFs whose methane working capacities exceed the target (315 cm3(STP) cm−3) are identified. Furthermore, structure–performance relationships are realized under the LNG–ANG condition using a machine learning method. Additional molecular dynamics simulations are conducted to investigate the effects of the structural changes during temperature and pressure swings, further narrowing down the materials, and two synthetic targets are identified. The synthesized DUT‐23(Cu) and DUT‐23(Co) show higher working capacities (≈373 cm3(STP) cm−3) than that of any other porous material under ANG or LNG–ANG conditions, and excellent stability during cyclic LNG–ANG operation.

Performance evolution analysis of a solid oxide cell operated in fuel-cell, electrolysis and cycle modes

Solid oxide cells (SOCs) are especially important in the context of a boom in the intermittent renewable energy. However, the widespread commercialization of SOCs is still constrained by stability. To investigate the performance evolution mechanisms, fuel-cell, electrolysis, and reversible operations of an industrial-size (10 cm × 10 cm) SOC were conducted. The electrochemical impedance spectroscopy (EIS) measured under open-circuit/a small DC bias and operating current was analyzed employing the distribution of relaxation times (DRT) method and equivalent circuit model (ECM) fitting. Under the fuel-cell and electrolysis modes, the resistances corresponding to the electrode processes held different change trends with increasing DC biases. Compared with the fuel-cell mode, the proportion of the resistance related to the gas diffusion and conversion processes of the fuel electrode was higher in the electrolysis mode. Meanwhile, the resistances associated with the charge transfer reaction, gas diffusion and conversion processes of fuel electrode increased faster in the electrolysis mode. Besides, through the evolution of j-V curves and resistances of electrode processes, the whole operation process was divided into the initial stage (first activation and then rapid-degradation) and the stable stage. In the post-mortem analysis, Ni non-percolating, Ni coarsening and change of pore morphology in the fuel electrode were mainly observed. Combined with the detailed EIS analysis and microstructure changes, the dominant performance evolution mechanism in different stages of the overall operation process was proposed.

Effects of Composite Accelerators on the Formation of Carbon Dioxide Hydrates.

To improve the rate of formation of carbon dioxide hydrates, tetra-n-butylammonium bromide (TBAB) was compounded with different concentrations of sodium dodecyl sulfate (SDS) and nanographite, and the effects of these mixtures on carbon dioxide hydrate formation were studied. The addition of TBAB alone, as well as mixtures of TBAB and SDS or nanographite, shortened the induced nucleation time, and the induction times of the TBAB–2.5 g/L nanographite and TBAB–0.24 g/L SDS systems were the shortest and longest, respectively. Further, on mixing TBAB and SDS, the induced nucleation time first increased and then decreased with the increase in the SDS concentration. When TBAB and nanographite were mixed together, the induced nucleation time first decreased, then increased, and again decreased with the increase in the nanographite concentration. In addition, the hydrate formation rate and conversion were highest for the TBAB–0.48 g/L SDS system and lowest for the TBAB–0.06 g/L SDS system; in the first 35 min, from the end of gas charging, the TBAB–10 g/L nanographite and TBAB–5 g/L nanographite systems yielded the highest and lowest hydrate formation rates and conversions, respectively. For the composite systems, obvious effects were observed in the initial stages of reaction, but the effects varied over the course of the reaction. Overall, the use of different accelerators resulted in little differences in the total production, conversion, and formation rate of carbon dioxide hydrates over the course of the reaction.

Reservoir Characteristics of Tight Sandstone and Sweet Spot Prediction of Dibei Gas Field in Eastern Kuqa Depression, Northwest China

Great progress has been made in the exploration of tight sandstone gas resources in Kuqa depression. Great progress has been made in Dibei structural belt, which proves the previously unproven favorable area for tight sandstone gas. The physical properties, controlling factors, and characteristics of tight sandstone from the Ahe (J1a) Formation in the Dibei gas reservoir are analyzed. The results show that the tight sandstone of the J1a Formation is mainly feldspar lithic sandstone, with low porosity (average 9.1%) and low permeability (average 0.09 mD). Compaction (average compaction rate 61.9%) reduces porosity more than cementation (average cementation rate 14.3%). Secondary dissolution pores (average thin section porosity is 3.4%) dominate. The homogenization temperature has two peaks; the first peak is 85–110 °C, and the other peak is 115–140 °C, indicating that oil and gas experienced two filling stages at 12 Ma and 4.5 Ma, respectively. Eodiagenesis, A substage of mesogenetic diagenesis, and B substage of mesogenetic diagenesis happened in the area. Tight sandstone is developed in the B substage of mesogenetic diagenesis. The main controlling factors of diagenesis are: strong dissolution and structural pore increase; oil and gas charging and overpressure. The reservoir forming mode of the Dibei gas reservoir is: crude oil filling in the Late Neogene (12 Ma); reservoir densification in the late deposition of Kangcun Formation (7 Ma), mature natural gas filling in the early deposition of Kuqa Formation (4.5 Ma), and gas reservoir formed after transformation and adjustment in the deposition period of Quaternary (2 Ma). According to this model, it is predicted that the favorable area of the Dibei gas reservoir is in the southeast of the Yinan 2 well. This study provides guidance for the study of tight sandstone gas in other areas of the Kuqa Depression.

Hydrocarbon Charge History of the Upper Paleozoic, Ordos Basin as Revealed by Fluid Inclusions

The petrographic characteristics of fluid inclusions of the main gas-bearing intervals of the Upper Paleozoic in the Ordos Basin are analyzed by means of plane-polarized light, fluorescence microscopy, and microthermometry. With the burial history of the basin, the charging and enrichment of natural gas in low-permeability reservoirs are also studied through a comparison of parameters such as the homogenization temperature and freezing temperature of aqueous inclusions associated with hydrocarbon inclusions. A comprehensive analysis of the assemblage characteristics, components, and temperature of fluid inclusions of the Upper Paleozoic shows that the abundance, attitude, and composition of gaseous hydrocarbon inclusions can reflect petroleum enrichment in low-permeability reservoirs. The homogenization temperature and freezing temperature of aqueous inclusions associated with gaseous hydrocarbon inclusions show no obvious discontinuities, indicating that natural gas charging was a long and continuous process since the Late Triassic to Early Cretaceous (210–100 Ma) and natural gas accumulation mainly occurred during the Early Cretaceous (125–100 Ma).

Reconfigurable Radio‐Frequency High‐Electron Mobility Transistors via Ferroelectric‐Based Gallium Nitride Heterostructure

AbstractThe wireless communication and power transmission environment varies widely depending on time and place, and thus reconfigurable devices and circuits are in high demand due to the significant increase in complexity of the power stage and chip size required for current non‐reconfigurable device‐based systems. Reconfigurable radio‐frequency (RF) devices, however, are difficult to demonstrate due to the lack of suitable materials with desirable material properties that can also be integrated with conventional high‐power materials. Here, reconfigurable gallium nitride (GaN) high‐electron mobility transistors (HEMTs) that are heterointegrated with 2D van der Waals‐interfaced α‐In2Se3 semiconductor are demonstrated. The switchable ferroelectric polarization of the 2D α‐In2Se3 layer is exploited to control the 2D electron gas charge density in the GaN channel. Further, a native interfacial indium oxide layer between the gate dielectric and α‐In2Se3 functions as a charge trapping layer, boosting the effect of the ferroelectric α‐In2Se3 layer. The fabricated HEMTs exhibit the sharpest subthreshold slope with tunable threshold voltage, transconductance, and maximum frequency in the range of several GHz under the application of a fast pulsed gate‐voltage signal without sacrificing the performance. The results clearly demonstrate the immense potential of ferroelectric‐based mixed‐dimensional heterostructures as a viable pathway toward simple and compact reconfigurable RF systems.

Three-dimensional hierarchical flowers-like cobalt-nickel sulfide constructed on graphitic carbon nitride: Bifunctional non-noble electrocatalyst for overall water splitting

Tailoring various micro-nano structured materials by employing different techniques to enhance their porosity and conductivity has captivated significant consideration, making their remarkable electrochemical properties accessible within the area of energy storage devices. Herein we report the impact of graphitic carbon nitride concentration (0.03 ∼ 0.1 g) on nickel-cobalt sulfide morphologies and performance in hydrogen production. Employing the facile hydrothermal method, a cubic crystalline nickel-cobalt sulfide was stabilized on defective layered graphitic carbon nitride nanosheets for overall water splitting. A performance peak was observed in a sample with a graphitic carbon nitride concentration of 50 mg, which not only prevented the agglomeration but also provided a porous structure for enhanced gas diffusivity and charge transfer rates owing to the synergistic Carbon and Nitrogen bonding with Cobalt and Nickel Sulfide. Optimized concentration of graphitic carbon nitride also increased the electrocatalytic active surface area threefold when compared with nickel-cobalt sulfide. The fabricated well-aligned flower-like pattern CoNi2S4/graphitic carbon nitride (50 mg) delivered a low overpotential of 310 mV and 160 mV for oxygen evolution reactions and hydrogen evolution reactions to reach a current density of 30 mA/cm2 and 10 mA/cm2 in alkaline media. The electrolyzer displayed an electrolysis potential of 1.58 V to reach 10 mA/cm2 current density with the long-term durability of 24 h. This strategy depicts a novel approach for utilizing this renowned nickel-cobalt sulfide with graphitic carbon nitride catalyst for the application of alkaline electrocatalytic water splitting.

A three dimensional visualized physical simulation for natural gas charging in the micro-nano pore system

A micro-nano pore three-dimensional visualized real-time physical simulation of natural gas charging, in-situ pore-scale computation, pore network modelling, and apparent permeability evaluation theory were used to investigate laws of gas and water flow and their distribution, and controlling factors during the gas charging process in low-permeability (tight) sandstone reservoir. By describing features of gas-water flow and distribution and their variations in the micro-nano pore system, it is found that the gas charging in the low permeability (tight) sandstone can be divided into two stages, expansion stage and stable stage. In the expansion stage, the gas flows continuously first into large-sized pores then small-sized pores, and first into centers of the pores then edges of pores; pore-throats greater than 20 μm in radius make up the major pathway for gas charging. With the increase of charging pressure, movable water in the edges of large-sized pores and in the centers of small pores is displaced out successively. Pore-throats of 20–50 μm in radius and pore-throats less than 20 μm in radius dominate the expansion of gas charging channels at different stages of charging in turn, leading to reductions in pore-throat radius, throat length and coordination number of the pathway, which is the main increase stage of gas permeability and gas saturation. Among which, pore-throats 30–50 μm in radius control the increase pattern of gas saturation. In the stable stage, gas charging pathways have expanded to the maximum, so the pathways keep stable in pore-throat radius, throat length, and coordination number, and irreducible water remains in the pore system, the gas phase is in concentrated clusters, while the water phase is in the form of dispersed thin film, and the gas saturation and gas permeability tend stable. Connected pore-throats less than 20 μm in radius control the expansion limit of the charging pathways, the formation of stable gas-water distribution, and the maximum gas saturation. The heterogeneity of connected pore-throats affects the dynamic variations of gas phase charging and gas-water distribution. It can be concluded that the pore-throat configuration and heterogeneity of the micro-nanometer pore system control the dynamic variations of the low-permeability (tight) sandstone gas charging process and gas-water distribution features.

Effective reservoir development model of tight sandstone gas in Shanxi Formation of Yan'an Gas Field, Ordos Basin, China

Through a large number of rock thin section microscopic observations, scanning electron microscopy analysis, and fluid inclusion homogenization temperature measurement, the lithological composition of tight reservoirs in the Shanxi Formation of the Yan'an Gas Field in the southeast of the Ordos Basin was studied, lithofacies types were classified, and the diagenetic evolution of different types of rocks was combined with the burial history, thermal history, and hydrocarbon charging process to analyze the time matching relationship between the key oil and gas charging period and reservoir densification. Studies have shown that pure quartz sandstone and quartz-rich low-plasticity lithic sandstone mainly develop mechanical compaction, secondary dissolution, and kaolinite precipitation. Before the two essential hydrocarbons are charged, the porosity is 15.8%–31.5%, which is typical of medium and high permeability reservoir rocks. The porosity of the high tuffaceous heterogeneous quartz sandstone, plastic-rich granular lithic sandstone, and carbonate tight cemented sandstone ranges from 4.6% to 10.8%, indicating that the reservoir is ultra-low porosity-low porosity reservoirs before the first key hydrocarbon charge. It is difficult to charge the hydrocarbons in the later stage. Therefore, the diagenesis of pure quartz sandstone and quartz-rich low-plastic granular lithic sandstone that maintained high porosity and permeability during early oil and gas charging has been inhibited, and the physical properties of the reservoir are relatively good. They are the primary migration channels and accumulation spaces for late-natural gas. This constitutes a sweet spot in tight sandstone gas reservoirs. The research findings are critical for understanding the coupling relationship between reservoir densification and accumulation, clarifying the formation mechanism of effective reservoir rocks, and predicting the distribution of sweet spots.

Phase fractionation controlling regional distribution of diamondoids: A case study from the Halahatang oil field, Tarim Basin, China

Large volumes of black and volatile oils have been recently discovered from 7000 m to 8400 m below surface in the Tarim Basin. Diamondoids, compounds recalcitrant to thermal stress, have been applied to estimate the extent of oil-cracking, but uncertainties remain concerning additional influences, such as evaporative fractionation and biodegradation. To investigate controls on diamondoid abundance in oil reservoirs, we performed detailed geochemical characterizations of biomarkers and diamondoids of twenty-eight oils from the Halahatang sub-Depression in the Tabei area of the Tarim Basin. Based on the results, the oils belong to one population. Three oils in the northeastern Halahatang area show the coexistence of n-alkanes and 25-norhopanes, indicating that early-expelled oils were severely biodegraded and then mixed with later, fresh charges of oil. Multiple molecular maturity indices suggest that oil maturities increase with depth. Interestingly, 3- + 4-methyldiamantanes, which should be enriched in highly mature oils, are found to be more abundant in less mature oils from shallower reservoirs, with exceptions of only four samples in the northeast. Published data for the eastern Lunnan area display a similar pattern that diamondoids are progressively enriched in shallower oils. The special pattern is interpreted to be the result of phase fractionation induced by a gas-dominated late charge. The late charge of gas firstly extracted diamondoids from deep-buried, highly-cracked oils through evaporative fractionation. As the vapor migrated towards the up-dip direction, decrease of pressure and temperature led to condensation of the diamondoids in the vapor. Briefly, the diamondoids were transferred to relatively shallow reservoirs through a combination of evaporative fractionation and subsequent phase separation. Alternatively, the abnormal enrichment of diamondoids in the northern part may be because of locally vertical charges of highly mature, diamondoid-rich gases through large faults.

Simulation of surface flashover probability distribution with gas-solid charge transport/multiplication coupling of epoxy resin

<p indent="0mm">The insulation failure of key equipment in power systems caused by gas-solid interface flashover of basin insulators is a key scientific problem that must be solved urgently. The time and space scales of gas electron multiplication and solid-surface charge evolution span multiple orders of magnitude, resulting in an unclear physical mechanism of the gas-solid coupling interface discharge of a basin insulator. A gas-solid coupling surface flashover model was established considering three junction point charge injection, solid surface charge transport, and gas collision ionization. The violent collision ionization in the gas caused by electrons emitted from the solid was taken as the surface flashover criterion. The key parameters characterizing surface charge transport and gas collision ionization were extracted based on gas-solid coupling surface flashover, and a model considering random variables was established to simulate the flashover voltage distribution of epoxy resin. The flashover voltage obeys the Weibull distribution when the charge transport parameters are Gaussian random variables, and the simulation results are consistent with the experimental results. By comparing the simulation and experimental results, it is found that the characteristic flashover voltage and distribution parameter are mainly controlled by the gas and solid media, respectively, and each charge transport random variable has a different effect on the distribution shape parameter. The Weibull distribution of flashover voltage consistent with the experimental results can be obtained by adjusting the standard deviation of charge transport random variables. This research explains the relationship between the Weibull distribution of flashover voltage and the charge transport and gas collision ionization parameters, providing an effective method to simulate the probability distribution characteristics of flashover voltage, which can also be used to evaluate the failure probability of the gas-solid interface under a certain voltage.

Analytical modeling of I–V characteristics using 2D Poisson equations in AlN/β-Ga2O3 HEMT

In this paper, physics-based analytical models using two-dimensional (2D) Poisson equations for surface potential, channel potential, electric field, and drain current in AlN/β-Ga2O3 high electron mobility transistor (HEMT) is presented. The analytical expression of different quantities is achieved based on full depletion approximation of the AlN barrier layer and polarization charge induced unified two-dimensional electron gas (2DEG) charge density model. For the validation of the developed model, results are compared with 2D numerical simulation results, and a good consistency is found between the two. The drain current model is also validated with experimental results of a similar dimension device. The developed model can be a good reference for different β-Ga2O3-based HEMTs.

Identification Method of Evolution Patterns of Favorable Oil and Gas Channels at Source Fault Configuration and Its Application

Favorable oil and gas channels during fault activity and cease episodes were determined to understand oil and gas distribution in reservoirs of “lower generation, upper accumulation”-type near faults in petroliferous basins through identifying and coupling conduit systems and hydrocarbon expulsion distribution during these periods, respectively. It was used to establish a method to identify the evolution patterns of favorable oil–gas charging positions at source fault configurations, which was applied to understand the evolution of favorable oil and gas channels in the middle and lower Es-3 sub-member in the southwest of the Jiuzhou fault. The results show that the conduit pattern in the Es-3 sub-member is mainly distributed in the center, west, and east of the F1 fault and the eastern part of the F7 fault in the southwest of the Jiuzhou fault. The conduit to non-conduit pattern is mainly distributed in the middle and center of the F7 fault. The non-conduit to conduit pattern is mainly distributed in the west and east of the F1 fault and the east of the F7 fault. The non-conduit is mainly distributed in the middle and east of the F7 fault. The conduit pattern and conduit to non-conduit pattern in the middle and lower Es-3 sub-member are favorable for hydrocarbon migration and accumulation. It is consistent with the oil and gas discovered in the middle and lower Es-3 sub-member near the southwest of the Jiuzhou fault, indicating that this method is feasible to identify the favorable oil and gas channels at source fault configurations.

Variable Valve Strategy Evaluation for Low-Load Operation in a Heavy-Duty Gasoline Compression Ignition Engine

By harnessing gasoline’s low reactivity for partially premixed combustion promotion, gasoline compression ignition (GCI) combustion shows the potential to produce markedly improved NOx-soot trade-off with high fuel efficiency compared to conventional diesel combustion. However, at low-load conditions, gasoline’s low reactivity poses challenges to attaining robust combustion with low unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions. Increasing the in-cylinder charge temperature by using variable valve actuation (VVA) can be an effective means to address these challenges. In this numerical investigation, VVA strategies, including (1) early exhaust valve opening (EEVO), (2) positive valve overlap (PVO), and (3) exhaust rebreathe (ExReb), were investigated at 1375 RPM and 2 bar brake mean effective pressure in a heavy-duty GCI engine using a market-based gasoline with a research octane number (RON) of 93. The total residual gas level was kept over 50% to achieve an engine-out NOx target of below 1.5 g/kWh. For a complete engine system analysis, one-dimensional (1-D) system-level modeling and three-dimensional (3-D) computational fluid dynamics (CFD) analysis were close-coupled in this study. Performance of the VVA strategies was compared in terms of in-cylinder charge and exhaust gas temperatures increase versus brake-specific fuel consumption (BSFC). The EEVO strategy demonstrated in-cylinder charge and exhaust temperature increase up to 130 and 180 K, respectively. For similar in-cylinder charge temperature gains, the ExReb strategy demonstrated 11% to 18% lower BSFC compared to the EEVO strategy. This benefit primarily originated from a more efficient gas-exchange process. The PVO strategy, due to the valve–piston contact constraint, required excessive exhaust back-pressure valve (BPV) throttling for hot residuals trapping, thereby incurring higher BSFC compared to ExReb. In addition, the ExReb strategy demonstrated the highest potential for exhaust temperature increase (up to 673 K) among the three strategies. This was achieved by ExReb’s maximum air-fuel ratio reduction from high internal residuals mass and BPV throttling. Finally, the ExReb profile was optimized in terms of the peak lift, the duration, and the location for maximizing the fuel-efficiency potential of the strategy.

Output prediction of alpha-type Stirling engines using gradient boosted regression trees and corresponding heat recovery system optimization based on improved NSGA-II

Climate change is becoming a pressing global concern, and the search for new energy and energy recovery technologies is becoming a worldwide research imperative. The broad adaptability of the Stirling engine to a wide variety of heat sources makes it a promising technology for industrial waste heat recovery and solar thermal generation. The operation of the Stirling engine involves a multi-physical coupled process of heat transfer and mechanics as well as non-linear losses due to mechanical friction and gas charge leaking. Therefore, accurate prediction of Stirling engine power output through theoretical analysis is complex and costly. Emerging machine learning algorithms like Gradient Boosted Regression Trees (GBRT) can offer new approaches to solve this problem. The GBRT model consists of multiple decision trees that branch by exhausting thresholds for all features under study to find the best split structure for data regression, and the principle of GBRT gives it the natural advantage of finding a wide range of distinguishing features and combinations, and a powerful generalization capability. A GBRT forecasting model is thus constructed to model the output power of Alpha-type Stirling engines. Test data from the General Motors 4L23 Stirling Engine are applied as the training and test set. Results from the random test set accounting for 25% of the total samples indicate that the GBRT model has a prediction accuracy of 96.23%. Furthermore, a regional microgrid containing Stirling engines, photovoltaic panels and batteries for industrial waste heat recovery is constructed and an evaluation system for energy supply performance is also established. Finally, based on the proposed power output model, multi-objective optimization based on improved NSGA-II is implemented, providing guidance for industrial application of Stirling engines.

Reservoir Densification, Pressure Evolution, and Natural Gas Accumulation in the Upper Paleozoic Tight Sandstones in the North Ordos Basin, China

The vague understanding of the coupling relationship among natural gas charging, reservoir densification, and pressure evolution restricted the tight gas exploration in the Lower Shihezi Formation of the Hangjinqi area, north Ordos Basin. In this study, the quantitative porosity evolution model, the pressure evolution process, and the natural gas charging history of tight sandstone reservoirs were constructed by integrated investigation of the reservoir property, the thin section, SEM and cathode luminescence observations, the fluid inclusion analysis and the 1D basin modeling. The results show that the compaction and cementation reduced the primary porosity by 21.79% and 12.41%, respectively. The densification of the reservoir occurred at circa 230 Ma, which was before the natural gas charging time from 192 to 132 Ma. The paleo-overpressure within the tight reservoirs occurred since the Middle Jurassic with the pressure coefficients between 1.1 and 1.55. The continuous uplifting since the Late Cretaceous resulted in the under- and normal-pressure of the Lower Shihezi Formation with the pressure coefficients ranging from 0.67 to 1.05. The results indicate that the densification of the reservoirs was conducive to the formation of paleo-pressure produced by gas generating. The gas predominantly migrated vertically, driven by gas expansion force rather than buoyance and displaced the pore water in the reservoirs near source rocks.

Exploring monolayer Janus MoSSe as potential gas sensor for Cl2, H2S and SO2

Based on first-principles calculations, the adsorption performance of several common poisonous gases (Cl2, H2S, SO2) on the monolayer Janus MoSSe and MoSSe-C are systematically studied. It can be found that Cl2, H2S and SO2 can all be adsorbed on MoSSe and MoSSe-C. The adsorption performance of MoSSe doped with C atom is better, and the binding strengths of gas molecules adsorbed on the S-layer doped with C atom are much stronger than those on Se-layer doped with C atom. The electronic structure of MoSSe-C changes differently under the adsorption of different gas molecules. By calculating the charge density difference and bader charge, the gas adsorption process and charge transfer are revealed. The charge transfer of MoSSe is enhanced by doping C atoms. Cl2, H2S and SO2 are easy to be adsorbed on the monolayer Janus MoSSe doped with C atoms. The monolayer MoSSe doped C atom is a sensitive gas sensor for Cl2, H2S and SO2, and it has potential application as an excellent gas sensor.

Hydrogen and deuterium charging of lifted-out specimens for atom probe tomography.

Hydrogen embrittlement can cause a dramatic deterioration of the mechanical properties of high-strength metallic materials. Despite decades of experimental and modelling studies, the exact underlying mechanisms behind hydrogen embrittlement remain elusive. To unlock understanding of the mechanism and thereby help mitigate the influence of hydrogen and the associated embrittlement, it is essential to examine the interactions of hydrogen with structural defects such as grain boundaries, dislocations and stacking faults. Atom probe tomography (APT) can, in principle, analyse hydrogen located specifically at such microstructural features but faces strong challenges when it comes to charging specimens with hydrogen or deuterium. Here, we describe three different workflows enabling hydrogen/deuterium charging of site-specific APT specimens: namely cathodic, plasma and gas charging. All the experiments in the current study have been performed on a model twinning induced plasticity steel alloy. We discuss in detail the caveats of the different approaches in order to help future research efforts and facilitate further studies of hydrogen in metals. Our study demonstrates successful cathodic and gas charging, with the latter being more promising for the analysis of the high-strength steels at the core of our work.

High-Performance Wearable Sensor Inspired by the Neuron Conduction Mechanism through Gold-Induced Sulfur Vacancies.

Practical application of wearable gas-sensing devices has been greatly inhibited by the poorly sensitive and specific recognition of target gases. Rapid charge transfer caused by rich sensory neurons in the biological olfactory system has inspired the construction of a highly sensitive sensor network with abundant defect sites for adsorption. Herein, for the first time, we demonstrate an in situ formed neuron-mimic gas sensor in a single gas-sensing channel, which is derived from lattice deviation of S atoms in Bi2S3 nanosheets induced by gold quantum dots. Due to the favorable gas adsorption and charge transfer properties arising from S vacancies, the fabricated sensor exhibits a significantly enhanced response value of 5.6-5 ppm NO2, ultrafast response/recovery performance (18 and 338 s), and excellent selectivity. Furthermore, real-time visual detection of target gases has been accomplished by integrating the flexible sensor into a wearable device.