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Fused phenazine-based organic redoxmers capable of six-electron redox activities have been designed and evaluated in aqueous flow batteries. Such a novel molecular engineering approach opens an avenue for enabling energy-dense storage strategies.

Lattice distortions and defects can lead to a strain effect that greatly affects the electronic structure of the noble metal surface and the chemical adsorption of ligands on the surfaces. Introducing defects is an efficient strategy to improve the activity of noble metal catalysts. Herein, a fusion approach is developed to fine-tune the defects and lattice strain in Au-Pd nanowires. Specifically, braided strands in Au-Pd nanoropes gradually coalesce to form solid nanowires upon H

Redoxmers or redox-active organic materials, are one critical component for nonaqueous redox flow batteries (RFBs), which hold high promise in enabling the time domain of the grid. While tuning redox potentials of redoxmers is a very effective way to enhance energy densities of NRFBs, those improvements often accompany accelerated kinetics of the charged species, undermining stability and cycling performance. Herein, a strategy for designing redoxmers with simultaneous improvements in redox potential and stability is proposed. Specifically, the redoxmer 1,4-di

The gas accumulation mode can be divided into two types based on the migration and accumulation characteristics: discontinuous accumulation into the reservoir rocks and continuous accumulation within or adjacent to the source rocks. Correspondingly, there are three different gas reservoirs including conventional, unconventional, and those in a transitional state. To demonstrate the differences in the formation mechanisms and distribution features of the two accumulation types, we have scrutinized the continuous accumulation and discontinuous accumulation in the Hangjinqi area of the Ordos Basin in North China. Continuous gas accumulation (basin-centered gas and water-soluble gas, as well as potential coalbed methane and shale gas) and discontinuous accumulation (various conventional gas traps) are, respectively, distributed in the southern and northern regions of the Hangjinqi area, which may change with the source-rock quality, migration force, reservoir capacity, and trapping condition. We identified that the essential factors influencing the formation and current distribution of gas reservoirs are the hydrocarbon generation ability, porosity, and cap rock-trap combinations in the study area. An ideal complete gas reservoir sequence develops coalbed methane, shale gas, basin central gas, water soluble gas, and conventional gas reservoirs from the center to the edge of the basin. Understanding the distribution characteristics of continuous accumulation and discontinuous accumulation allows better prediction of the potential gas reservoir types with the knowledge of discovered reservoirs. We recommend exploring anticline gas reservoirs in areas north of the Boerjianghaizi fault and basin-centered gas reservoirs in areas south of the Boerjianghaizi fault. We also suggest performing further research on shale source rocks because the maturity and the burial depth of the marine-continental organic-rich shale in the Shanxi-Taiyuan Formations are recognized to be favorable for shale gas generation and preservation.

The power density of axial piston pumps can benefit greatly from increased rotational speeds. However, the maximum rotational speed of axial piston machines is limited by the cavitation phenomenon for a given volumetric displacement. This paper presents a scaling law derived from an analytical cavitation model to estimate the speed limitations for the same series of axial piston pumps. The cavitation model is experimentally verified using a high-speed axial piston pump, and the scaling law is validated with open specification data in product brochures. Results show that the speed limitation is approximately proportional to the square root of the inlet pressure and inversely proportional to the cube root of volumetric displacement. Furthermore, a characteristic constant Cp is defined based on the presented scaling law. This constant can represent the comprehensive capacity of axial piston pumps free from cavitation.

Fractal dimension is closely related to the nanoscale pore structure of shale, and it also has an important influence on the gas content of shale. To investigate the correlation between the fractal dimension and the methane (CH4) bearing features of shale, seven Permian shale samples were analyzed with field emission scanning electron microscopy (FE-SEM), low temperature nitrogen (N2), carbon dioxide (CO2) and CH4 adsorption and on-site gas desorption experiments. Based on the N2 adsorption and desorption data, we proposed a new method to better determine the gas adsorption stage at different relative pressure (P/P0) points in the multilayer adsorption or capillary condensation stage. On this basis, two fractal dimensions, D1 (representing the surface roughness) and D2 (representing pore irregularity), were obtained. By correlating the fractal dimensions and nanoscale pore structure parameters, we found that D1 does not correlate with the pore structure parameters except for the micropore volume. Influenced by the aggregation of porous and nonporous materials, D2 has a positive linear relationship with the specific surface area (SSA) and micropore volume but has a negative linear correlation with the average diameter of pores. D1 is negatively correlated with water saturation and positively correlated with free CH4 content. The CH4 adsorption content is positively correlated with D2. By fitting the on-site desorption data, the positive correlation between the total desorbed CH4 content and the desorbed CH4 content in stage 2 and D2 was also confirmed. D2 better reflects the CH4 adsorption capacity of organic-rich shale than D1. However, D1 can be used to reflect the influence of shale surface properties on water saturation and to indirectly reflect the free CH4 content in shale. The fractal dimension (D1 and D2) is a clear indicator of the total free and adsorbed CH4 content, but cannot indicate the desorbed CH4 content at different stages.

Raising rotational speed is an effective way to improve power density of axial piston pumps, but high rotational speed tends to cause undesirable cavitation in the pump. Although some machine learning methods have been successfully applied to detect the cavitation with high accuracy, these conventional methods suffer from the drawback of time-consuming and experience-dependent manual feature extraction. In this paper, a new model based on 1-D convolutional neural network (CNN) is proposed to recognize the cavitation intensity of axial piston pumps. To improve the recognition accuracy under noisy environment, the 1-D CNN receives multi-channel vibration data instead of single-channel data. The experimental results show that the proposed anti-noise 1-D CNN model with multi-channel inputs can achieve 15% higher recognition accuracy than its counterpart with single-channel input on a testing set with SNR = 5 dB.

Spinal cord injury can lead to incomplete or complete loss of voluntary movement and sensory function, leading to serious complications. Numerous studies have shown that progesterone exhibits strong therapeutic potential for spinal cord injury. However, the mechanism by which progesterone treats spinal cord injury remains unclear. Therefore, this article explores the mechanism of progesterone in the treatment of spinal cord injury by means of molecular docking and molecular dynamics simulation.We used bioinformatics to screen active pharmaceutical ingredients and potential targets, and molecular docking and molecular dynamics were used to validate and analysis by the supercomputer platform.Progesterone had 3606 gene targets, spinal cord injury had 6560 gene targets, the intersection gene targets were 2355. GO and KEGG analysis showed that the abundant pathways involved multiple pathways related to cell metabolism and inflammation. Molecular docking showed that progesterone played a role in treating spinal cord injury by acting on BDNF, AR, NGF and TNF. Molecular dynamics was used to prove and analyzed the binding stability of active ingredients and protein targets, and AR/Progesterone combination has the strongest binding energy.Progesterone promotes recovery from spinal cord injury by promoting axonal regeneration, remyelination, neuronal survival and reducing inflammation.

Objective The 30‐day readmission is associated with increased medical costs, which has become an important quality metric in several medical institutions. This current study is aimed at clarifying the prevalence, the underlying risk factors, and reasons of the 30‐day readmission after acute myocardial infarction (AMI). Methods PubMed, Cochrane Library, and EMBASE were systematically searched to identify eligible studies. Random‐effect models were employed to perform pooled analyses. Means and 95% confidence intervals (CIs) were used to estimate prevalence and reasons for 30‐day readmission. We also used Odds ratios (ORs) to explore the potential significant predictors of risk factors of 30‐day readmission after AMI. Potential publication bias was assessed using funnel plot and Begg'test. Results A total of 14 relevant studies were included in this systematic review and meta‐analysis. The pooled 30‐day readmission rate of AMI was 12% (95% CI 0.11‐0.14). Acute coronary syndrome (ACS), angina and acute ischemic heart disease, and heart failure (HF) were the principal cardiovascular reasons of 30‐day readmission. Meanwhile, non‐specific chest pain was regarded as the significant cause among non‐cardiovascular reasons. The common co‐morbidities kidney disease, HF and diabetes mellitus were significant risk factors for 30‐day readmission. No significant publication bias was found by funnel plot and statistical tests. Conclusions The 30‐day readmission rate of post‐AMI ranged from 11% to 14% and can be mainly attributed to cardiovascular and non‐cardiovascular events. The common co‐morbidities, such as kidney disease, HF, and diabetes mellitus were significant risk factors for 30‐day readmission.

In this study, we present a comprehensive experimental and modeling study on six shale samples to investigate the effect of shale composition and pressure on methane diffusivity. By correlating shale composition, pressure, and methane diffusivity, it was found that both macro- and micropore diffusivity decreased with increasing pressure, while total organic carbon content had little effect on macropore diffusivity and negatively affected micropore diffusivity. This phenomenon may be a result of nonporous organic matter (OM) in transitional shale acting as solid material instead of porous media, occupying micropore volume, prolonging gas diffusion length, and increasing diffusion resistance. Clay minerals with connected microstructures positively affect micropore diffusivity while negatively affecting macropore diffusivity, which may be a result of the filling of macropores with clay particles, blocking gas diffusion pathways, and increasing gas diffusion resistance. Brittle minerals have a positive effect...

Myocardial infarction (MI) is a severe cardiovascular disease. Some M1 macrophage-derived extracellular vesicles (EVs) are involved in the inhibition of angiogenesis and acceleration dysfunction during MI. However, the potential mechanism of M1 phenotype bone marrow-derived macrophages- (BMMs-) EVs (M1-BMMs-EVs) in MI is largely unknown. This study sought to investigate whether M1-BMMs-EVs increased CDC42 expression and activated the MEK/ERK pathway by carrying lncRNA MALAT1 and competitively binding to miR-25-3p, thus inhibiting angiogenesis and myocardial regeneration after MI. After EV treatment, the cardiac function, infarct size, fibrosis, angiogenesis, and myocardial regeneration of MI mice and the viability, proliferation and angiogenesis of oxygen-glucose deprivation- (OGD-) treated myocardial microvascular endothelial cells (MMECs) were assessed. MALAT1 expression in MI mice, cells, and EVs was detected. MALAT1 downstream microRNAs (miRs), genes, and pathways were predicted and verified. MALAT1 and miR-25-3p were intervened to evaluate EV effects on OGD-treated cells. In MI mice, EV treatment aggravated MI and inhibited angiogenesis and myocardial regeneration. In OGD-treated cells, EV treatment suppressed cell viability, proliferation, and angiogenesis. MALAT1 was highly expressed in MI mice, OGD-treated MMECs, M1-BMMs, and EVs. Silencing MALAT1 weakened the inhibition of EV treatment on OGD-treated cells. MALAT1 sponged miR-25-3p to upregulate CDC42. miR-25-3p overexpression promoted OGD-treated cell viability, proliferation, and angiogenesis. The MEK/ERK pathway was activated after EV treatment. Collectively, M1-BMMs-EVs inhibited angiogenesis and myocardial regeneration following MI via the MALAT1/miR-25-3p/CDC42 axis and the MEK/ERK pathway activation.

Myocardial infarction represents one of the severe cardiovascular diseases and is one of the high-risk factors for mortality, and ischemia/reperfusion (I/R) injury is one of the risk factors that contribute to the high mortality of myocardial infarction. MicroRNAs have been proven as key regulators in various diseases including myocardial infarction. The present study was sought to determine the role of miR-703 in the myocardial I/R injury and to explore detailed mechanisms. Hypoxia/reoxygenation (H/R) treatment repressed cell viability, increased cytotoxicity and pyroptosis in mouse cardiomyocytes. More importantly, we found that miR-703 was suppressed in mouse cardiomyocytes upon H/R stimulation. Restoration of miR-703 expression in mouse cardiomyocytes counteracted the H/R-induced cytotoxicity and pyroptosis in mouse cardiomyocytes; and the effects of miR-703 inhibition on cell viability and pyroptosis were similar to that of H/R treatment in mouse cardiomyocytes. In a further investigation, we found that NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) was targeted and repressed by miR-703 in mouse cardiomyocytes. NLRP3 knockdown also attenuated H/R-induced cytotoxicity and pyroptosis in mouse cardiomyocytes. In the mechanistic perspective, NLRP3 enforced expression disrupted the protective effects of miR-703 restoration on the H/R-induced cytotoxicity and pyroptosis in mouse cardiomyocytes. Our results for the first time demonstrate the protective actions of miR-703 in the H/R-induced mouse cardiomyocyte injury. More importantly, miR-703 protects against H/R-induced cardiomyocyte injury via inhibiting the NLRP3/caspase-1-mediated pyroptosis.

The vibration signal is a good indicator of cavitation in axial piston pumps. Some vibration-based machine learning methods have been developed for recognizing pump cavitation. However, their fault diagnostic performance is often unsatisfactory in industrial applications due to the sensitivity of the vibration signal to noise. In this paper, we present an intelligent method for recognizing the cavitation severity of an axial piston pump in a noisy environment. First, we adopt short-time Fourier transformation to convert the raw vibration data into spectrograms that act as input images of a modified LeNet-5 convolutional neural network (CNN). Second, we propose a denoising method for the converted spectrograms based on frequency spectrum characteristics. Finally, we verify the proposed method on the dataset from a test rig of a high-speed axial piston pump. The experimental results indicate that the denoising method significantly improves the diagnostic performance of the CNN model in a noisy environment. For example, using the denoising method, the accuracy rate forcavitation recognition increases from 0.52 to 0.92 at a signal-to-noise ratio of 4 dB.

Redox-active organic materials (ROMs) are becoming increasingly attractive for use in redox flow batteries as promising alternatives to traditional inorganic counterparts. However, the reported ROMs are often accompanied by challenges, including poor solubility and stability. Herein, we demonstrate that the commonly used diquat herbicides, with solubilities of >2 M in aqueous electrolytes, can be used as stable anolyte materials in organic flow batteries. When coupled with a ferrocene-derived catholyte, the flow cells with the diquat anolyte demonstrate long galvanic cycling with high capacity retention. Notably, the mechanistic underpinnings of this remarkable stability are attributed to the improved π-conjugation that originated from the near-planar molecular conformations of the spatially constrained 2,2′-bipyridyl rings, suggesting a viable structural engineering strategy for designing stable organic materials.

An all-vanadium redox flow battery with V(IV) as the sole parent active species is developed by accessing the VO2+/V3+ redox couple. These batteries, referred to as V4RBs, possess a higher theoretical volumetric capacity than traditional VRBs. Copper ions were identified as an effective additive to boost the battery performance.

Aqueous soluble organic (ASO) redox-active materials have recently attracted significant attention as alternatives to traditional transition metal ions in redox flow batteries (RFB). However, reported reversible capacities of ASO are often substantially lower than their theoretical values based on the reported maximum solubilities. Here, we describe a phenazine-based ASO compound with an exceptionally high reversible capacity that exceeds 90% of its theoretical value. By strategically modifying the phenazine molecular structure, we demonstrate an increased solubility from near-zero with pristine phenazine to as much as 1.8 M while also shifting its redox potential by more than 400 mV. An RFB based on a phenazine derivative (7,8-dihydroxyphenazine-2-sulfonic acid) at its near-saturation concentration exhibits an operating voltage of 1.4 V with a reversible anolyte capacity of 67 Ah l−1 and a capacity retention of 99.98% per cycle over 500 cycles. Redox flow batteries (RFBs) based on organic redox-active molecules are attractive, but the solubility of those molecules, and consequently the capacity, is generally low. Here, the authors develop a phenazine derivative with high solubility as an energy-dense anolyte for RFBs.

Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study, eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality. Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit (ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit (MCF) method, based on the ‘bidisperse’ diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation (USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, the ACF and MCF methods, are the best options respectively.

Understanding structure–property relationships is essential for designing energy-rich redox active organic molecules (ROMs) for all-organic redox flow batteries. Herein we examine thiadiazole ROMs for storage of negative charge in the flow cells. These versatile molecules have excellent solubility and low redox potentials, allowing high energy density to be achieved. By systematically incorporating groups with varying electron accepting/withdrawing ability, we have examined substituent effects on their properties of interest, including redox potentials, calendar lives of charged ROMs in electrolyte, and the flow cell cycling performance. While the calendar life of energized fluids can be tuned in a predictable fashion over a wide range, the improvements in the calendar life do not automatically translate into the enhanced cycling performance, indicating that in addition to the slow reactions of charged species in the solvent bulk, there are other parasitic reactions that occur only during the electrochemical cycling of the cell and can dramatically affect the cycling lifetime.

K3[Fe(CN)6] and K4[Fe(CN)6] have been frequently applied in redox flow batteries to achieve sustainable and economical renewable energy storage. However, fundamental knowledge of the redox couple of K3[Fe(CN)6] and K4[Fe(CN)6] regarding their flow battery performance is largely underdeveloped. Herein, we present a comprehensive study on the fundamental properties and electrochemical kinetics of K3[Fe(CN)6] and K4[Fe(CN)6] in aqueous supporting electrolytes at different pH values. Particularly, the charge/discharge cycling stability of the redox couple was evaluated at different pH values using a half-cell flow battery configuration. The battery results unambiguously confirmed that the redox couple functions best at neutral or near neutral conditions. Dramatic capacity decay of the redox couple was observed in a strong alkaline KOH electrolyte (pH =14), which is due to the chemical decomposition associated with the CN- ligand dissociation. The presented study not only advances an in-depth understanding of K3[Fe(CN)6] and K4[Fe(CN)6] regarding their flow battery applications but also highlights the challenge of acid-base side reactions of redox active molecules applied in aqueous acidic/alkaline redox flow batteries.

The development of natural microfractures not only directly affects exploitation efficiency of a shale gas reservoir, but also determines the quality and production of the shale gas reservoir. The environment, in which the shale forms, is considered to be the fundamental cause of shale pore formation and deformation. However, the traditional method of observing shale samples using field-emission scanning electron microscopy (FE-SEM) can be interfered by a large number of fractures caused by artificial damage on the shale surface during sample preparation, such as mechanical damage during polishing and shrinkage damage of shale mineral particles. To tackle this issue, we summarized the features of natural fractures by comparing fracture morphology of shale before and after artificial damage. In this study, the powder samples which suffered serious structural damage and the block samples with light structural damage were observed by FE-SEM. In addition, we used the pressure switch to cause slight damage to the surface of gold-plated block samples, and the difference between the gold film tearing edge and the mineral tearing edge was used to identify the artificial cracks generated during this process. We found (1) most of the open structural fractures on the shale surface are not natural, but artificially induced during the sample preparation process; (2) most non-structural natural fractures are mainly related to organic matter, clay and calcite; (3) stress and shrinkage are the main causes of natural microfractures; (4) natural microfractures in shale have a clear pressure support structure, which are categorized into self-supporting fractures.

Redox flow batteries (RFBs) are propitious stationary energy storage technologies with exceptional scalability and flexibility to improve the stability, efficiency, and sustainability of our power grid. The redox-active materials are the key component for RFBs with which to achieve high energy density and good cyclability. Traditional inorganic-based materials encounter critical technical and economic limitations such as low solubility, inferior electrochemical activity, and high cost. Redox-active organic materials (ROMs) are promising alternative “green” candidates to push the boundaries of energy storage because of the significant advantages of molecular diversity, structural tailorability, and natural abundance. Here, the recent development of a variety of ROMs and associated battery designs in both aqueous and nonaqueous electrolytes are reviewed. The critical challenges and potential research opportunities for developing practically relevant organic flow batteries are discussed.

Sunlight-driven natural seawater splitting provides a promising way for large-scale conversion and storage of solar energy. Here, we develop a facile and low-cost method via a deposition–annealing technique to fabricate porous WO3 film and demonstrate its application as a photoanode for natural seawater splitting. The WO3 film yields a photocurrent density of 1.95 mA cm−2 and possesses excellent stability at 1.23 V (versus RHE), under the illumination of 100 mW cm−2 (AM 1.5G). The photoelectrochemical performance is ascribed to the large surface area and good permeation of the electrolyte into the porous film. Furthermore, the photocurrent density remains almost the same during 3 h continuous light irradiation. The evolution of chlorine gas from seawater splitting was determined with qualitative and quantitative analyses, with a Faradic efficiency of about 56%.

Redox-active organic materials (ROMs) have shown great promise for redox flow battery applications but generally encounter limited cycling efficiency and stability at relevant redox material concentrations in nonaqueous systems. Here we report a new heterocyclic organic anolyte molecule, 2,1,3-benzothiadiazole, that has high solubility, a low redox potential, and fast electrochemical kinetics. Coupling it with a benchmark catholyte ROM, the nonaqueous organic flow battery demonstrated significant improvement in cyclable redox material concentrations and cell efficiencies compared to the state-of-the-art nonaqueous systems. Especially, this system produced exceeding cyclability with relatively stable efficiencies and capacities at high ROM concentrations (>0.5 M), which is ascribed to the highly delocalized charge densities in the radical anions of 2,1,3-benzothiadiazole, leading to good chemical stability. This material development represents significant progress toward promising next-generation energy st...

The goal of this paper is to investigate the geological controls on the methane adsorption capacity of Lower Permian transitional black shales. To this end, a variety of methods, including quantifying organic matter richness, vitrinite reflectance, kerogen stable isotope analysis, X-ray diffraction (XRD), low-pressure nitrogen adsorption, and high-pressure methane adsorption were performed on black shale samples collected from the Mouye-1 well in the Southern North China Basin. Among them, high-pressure methane adsorption experiments were performed over a pressure range of 0–20 MPa at temperatures of 30 °C, 40 °C, and 50 °C. Then, the effects of organic matter, mineral compositions, pore properties, temperature, and pressure on methane adsorption capacity were analyzed, and a new formula for predicting the gas adsorption capacity and methane adsorption capacity of transitional shales as a function of burial depth in the Southern North China Basin was established. Experimental results indicate that the total organic carbon content (TOC) of shales in the present study ranges from 0.49% to 2.37% with an average value of 1.14%. The thermal maturity of these samples, as reflected by their vitrinite reflectance (R o ) values, demonstrates that all involved shale samples have extremely high thermal maturities with an average value of 3.23%. The levels of kerogen stable carbon isotopes (δ 13 C PDB ) range from −25.00‰ to −24.10‰, thereby indicating the presence of primarily type III organic matter within these shale samples. Mineral compositions mainly comprise clay minerals and quartz with average values of 57.8% and 37.6%, respectively. Within clay mineral populations, illite, kaolinite, I-S mixed layer clays, and chlorite are the dominant clay minerals. BET (Brunauer-Emmett-Teller) surface area and total pore volumes of the studied shale samples range from 4.7085 m 2 /g to 9.1883 m 2 /g and 0.01069 cm 3 /g to 0.01802 cm 3 /g, respectively. Under the measured pressure range, methane adsorption capacity correlates positively with TOC content, likely due to the increase in surface area and total pore volume with increasing TOC content. Nanometer-scale pores ranging from 2 to 10 nm, as revealed by low-pressure nitrogen adsorption, are the main contributors to surface area and total pore volume within these shales. Although the TOC-normalized surface area increases with thermal maturity, a negative correlation between thermal maturity and methane adsorption capacity was observed in the present study, most likely due to the decrease in TOC during thermal maturation. A weak positive quadratic correlation was also observed between clay mineral contents and methane adsorption capacity, with the Langmuir volume initially decreasing before subsequently increasing with increasing total clay content, thereby indicating that clay minerals have a weaker effect than TOC on methane adsorption capacity. Geologically applying the methane adsorption capacity of shales as a function of burial depth, which was established based on the Langmuir model, indicates that the methane adsorption capacity of transitional shales initially increases before ultimately decreasing as the depth increases due to the joint effects of temperature and pressure.

The fundamental correlations between solubility and solvation structure for the electrolyte system comprising N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium bistrifluoromethylsulfonimide (Fc1N112-TFSI) dissolved in a ternary carbonate solvent mixture is analyzed using combined NMR relaxation and computational methods. Probing the evolution of the solvent–solvent, ion–solvent and ion–ion interactions with an increase in solute concentration provides a molecular level understanding of the solubility limit of the Fc1N112-TFSI system. An increase in solute concentration leads to pronounced Fc1N112-TFSI contact-ion pair formation by diminishing solvent–solvent and ion–solvent type interactions. At the solubility limit, the precipitation of solute is initiated through agglomeration of contact-ion pairs due to overlapping solvation shells.

Nonaqueous redox flow batteries are promising in pursuit of high energy density storage systems owing to the broad voltage windows (>2 V) but currently are facing key challenges such as limited cyclability and rate performance. To address these technical hurdles, here we report the nonaqueous organic flow battery chemistry based on N-methylphthalimide anolyte and 2,5-di-tert-butyl-1-methoxy-4-[2′-methoxyethoxy]benzene catholyte, which harvests a theoretical cell voltage of 2.30 V. The redox flow chemistry exhibits excellent cycling stability under both cyclic voltammetry and flow cell tests upon repeated cycling. A series of Daramic and Celgard porous separators are evaluated in this organic flow battery, which enable the cells to be operated at greatly improved current densities as high as 50 mA cm–2 compared to those of other nonaqueous flow systems. The stable cyclability and high-current operations of the organic flow battery system represent significant progress in the development of promising nonaqu...

Understanding the solvation structures of electrolytes is important for developing nonaqueous redox flow batteries that hold considerable potential for future large scale energy storage systems. The utilization of an emerging ionic-derivatived ferrocene compound, ferrocenylmethyl dimethyl ethyl ammonium bis(trifluoromethanesulfonyl)imide (Fc1N112-TFSI), has recently overcome the issue of solubility in the supporting electrolyte. In this work, 13C, 1H and 17O NMR investigations were carried out using electrolyte solutions consisting of Fc1N112-TFSI as the solute and the mixed alkyl carbonate as the solvent. It was observed that the spectra of 13C experience changes of chemical shifts while those of 17O undergo linewidth broadening, indicating interactions between solute and solvent molecules. Quantum chemistry calculations of both molecular structures and chemical shifts (13C, 1H and 17O) are performed for interpreting experimental results and for understanding the detailed solvation structures. The results indicate that Fc1N112-TFSI is dissociated at varying degrees in mixed solvent depending on concentrations. At dilute solute concentrations, most Fc1N112+ and TFSI− are fully disassociated with their own solvation shells formed by solvent molecules. At saturated concentration, Fc1N112+-TFSI- contact ion pairs are formed and the solvent molecules are preferentially interacting with the Fc rings rather than interacting with the ionic pendant arm of Fc1N112-TFSI.

Solar splitting of seawater is one of the promising ways for large scale utilization of solar energy in the future. Here we reported an efficient and stable photoanode based on earth-abundant materials for photoelectrochemical (PEC) splitting of natural seawater. Through simple hydrothermal growth and deposition-annealing (DA) process, α-Fe 2 O 3 /WO 3 nanorod arrays were grown on the surface of fluorine-doped tin oxide coated glass. The PEC performance can be optimized simply by varying DA cycles. The photocurrent density reaches about 1 mA/cm 2 at 1.23 V vs RHE under the illumination of 100 mW/cm 2 (AM 1.5G) which is 2.9 times as that of pure WO 3 films and 50 times as that of the pristine Fe 2 O 3 NRs under the same conditions. More importantly, when the materials were used as photoanode for PEC splitting of natural seawater, the performance was kept as well. After 5 h continuous illumination 65% of the initial value of photocurrent density still remained, which imply the good photostability of the materials even at the conditions of PEC splitting of seawater. A possible mechanism for the improved performance of the hybrid photoanode was proposed based on our experimental results.

Hydrogen production from seawater and solar energy based on photoelectrochemical cells is extremely attractive due to earth-abundance of seawater and solar radiation. Herein, we report the successful fabrication of novel inorganic-organic 2D/2D WO3/g-C3N4 nanosheet arrays (WO3/g-C3N4 NSAs) grown on a FTO substrate via a facile hydrothermal growth and deposition-annealing process, and their application in natural seawater splitting. The results indicate that the WO3/g-C3N4 NSAs exhibit a photocurrent density of 0.73 mA cm(-2) at 1.23 V versus RHE under AM 1.5G (100 mW cm(-2)) illumination, which is 2-fold higher than that of WO3 NSAs. More importantly, the WO3/g-C3N4 NSA photoanode is quite stable during seawater splitting and the photocurrent density does not substantially decrease after continuous illumination for 3600 s. The remarkably enhanced performance originates primarily from the formation of the WO3/g-C3N4 heterojunction between WO3 and g-C3N4 nanosheets, which accelerates charge transfer and separation, and prolongs the lifetime of electrons as demonstrated by EIS and Mott-Schottky analyses. Finally, a possible mechanism for the improved performance was proposed and discussed.

With the purpose of characterizing the organic geochemistry and investigating the shale gas potential, we applied multiple methods, including quantifying organic matter richness, polarizing microscope observations, maceral composition analysis, kerogen stable carbon isotope analysis, vitrinite reflectance analysis, and Rock-Eval pyrolysis were performed on black shale samples from the Lower Permian Shanxi and Taiyuan formations in the Mouye-1 well of the Southern North China Basin. The results indicate that the average total organic carbon (TOCpd) content at the present time is 1.73% and 2.41% for Shanxi and Taiyuan shale samples, respectively. The microscopic distribution of organic matter includes scattered types and local enrichment types, as well as layered enrichment types. These types were revealed by polarizing microscope observations and exhibit an excellent correlation with the TOC content of shale samples. Based on maceral compositions and kerogen stable carbon isotopes, organic matter in Shanxi and Taiyuan shales is characterized by gas-prone, inertinite-dominated type III kerogen. The thermal maturity, as indicated by measuring vitrinite reflectance (3.2–3.6%Ro), suggests that shale samples from Shanxi and Taiyuan formation in the Mouye-1 well have evolved far into the metagenesis stage, and no significant amounts of hydrocarbons can be generated. The remaining hydrocarbon generative potential, S2 (0.02–0.77 mg HC/g Rock), which was determined by Rock-Eval pyrolysis, also supports this conclusion. Additionally, the original total organic carbon (TOCo) content and hydrocarbon generative potential (S2o) were reconstructed based on Jarvie's equations for these thermally over-mature shales; this reconstruction indicated poor to fair original source rock potentials based on the correlations of TOCo and S2o. Furthermore, the total volume of gas generated during thermal maturation was calculated using a conversion formula based on molar mass and resulted in a yield of 5.69 cm3/g Rock and 3.54 cm3/g Rock for Shanxi and Taiyuan shale samples, respectively. Overall, inertinite-dominated maceral compositions of kerogen with extremely high thermal maturity can have a negative effect on the gas potential of shale in the Southern North China Basin.

Power density is an important attribute for aviation hydraulic pumps, which can benefit much from improving rotational speed. However, cavitation tends to occur in the pump at high rotational speeds and thus decreasing its volumetric efficiency and lifetime. Therefore, cavitation identification is essential and urgent for high-speed aviation hydraulic pumps. In this paper, we propose a real-time method for identifying the cavitation conditions based on the vibration signals measured at pump housing. The collected three-channel vibration data are cut into frames to be transformed into RGB images, and then these images are fed to a 2-D convolutional neural network (CNN) to identify the levels of cavitation intensity. The experimental results show that the CNN model can achieve high accuracy rates when it accepts optimal RGB images. In addition, RGB images are found to be more robust against noise than gray counterparts in the case of vibration based cavitation identification.

This research article selects supercritical methane and organic-rich shale as adsorbate-adsorbent pair to investigate methane adsorption behavior and enrich our understanding of the nature of shale gas adsorption process. The isotherms and kinetics of methane-shale adsorption pair are measured at temperatures of 303 K, 323 K, 343 K and 363 K by using a volumetric experimental setup. Then, the Langmuir-based (Langmuir, Langmuir + k, Langmuir + Henry), BET-based (BET, BET + k, BET + Henry) and DA-based (DA, DA + k and DA + Henry) excess models are used to interpret measured excess isotherms, and the Unipore Diffusion (UD), Bidisperse Diffusion (BD) and Two Combined First-Order Rate (TCFOR) models are used to interpret the adsorption kinetics data. Instead of using the coefficient of determination (R2), this work used the corrected Akaike’s Information Criterion (AICc) for model selection. It is found that the DA + Henry model is more suitable for excess adsorption isotherms, and the TCFOR model is more appropriate for adsorption kinetics study. Additionally, for methane-shale adsorption under supercritical condition, the fugacity is of great significance in evaluating thermodynamic properties including isosteric heat of adsorption (qst), enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy change (ΔG). These properties show strong dependence on adsorption amount and temperature, and suggest that supercritical methane adsorption on organic-rich shale is a process of physisorption, exothermic and spontaneous. Further, the kinetics parameters extracted from kinetics curves suggest that the methane adsorption at each pressure step is a two-stage process, with a fast macropore diffusion process at early time, followed by a slow micropore diffusion process at later time. Additionally, the fast macropore diffusion dominates the two-stage adsorption process at lower pressures, while at higher pressures slow micropore diffusion dominates.

The Carboniferous-Permian Qinshui Basin has shale gas resource potential. In this study, eighteen shale samples from two representative wells were analyzed to investigate the coal-measure shale reservoir characteristics and their relationships with the transitional sedimentary environments. The results show that controlled by sedimentary environments, the tidal flat and barrier-lagoon (TFBL) system is prone to developing more organic matter (OM) than the pro-delta and delta front (PDDF) and delta plain and fluvial (DPF) systems. Shale porosity is positively correlated with clay mineral content, but shows no obvious relationship with quartz content. However, biogenic quartz content exhibits a negative correlation with shale porosity, but has a positive correlation with shale brittleness in the PDDF system, while no obvious correlation between detrital quartz and reservoir quality is found in the TFBL system. In terms of its better preservation of pyrite, which improves shale reservoir brittleness, there is more enhancement of the shale reservoir quality within the TFBL system than the PDDF system. The coal-measure shale samples exhibit a positive logarithmic correlation between reservoir porosity and permeability due to the pore size distribution. In terms of micropores (pore size