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Coalbed methane (CBM) seepage is a significant geological factor affecting the capacity of CBM wells. Using the example of the Qinnan-East Block of the Qinshui Basin, in this work, the CBM seepage law under different in situ stresses, coal reservoir pressures, and temperatures is systematically analyzed using on-site well test data. A permeability calculation model that includes the coal reservoir stress, pressure, and temperature is established, and the coal permeability and its control mechanism under the action of multiple fields are revealed. The results demonstrate that the in situ stress, pressure, and temperature in the study area increase linearly with increasing depth. The coal reservoir geothermal gradient is 0.72–2.11 °C/100 m, and the mean value is 1.67 °C/100 m. The coal reservoir geothermal gradient rises with an increasing depth as a logarithmic function. The permeability of the coal reservoir is 0.01–0.20 × 10−3 μm2, the mean value is 0.05 × 10−3 μm2, and the CBM seepage under the action of multiple physical fields is relatively low. With increasing effective stress and temperature, the permeability continuously decreases following a negative exponential function. The CBM seepage is tightly bound to the fracture aperture and is controlled by the change in the in situ stress, the pore fluid pressure, and the temperature stress. [ABSTRACT FROM AUTHOR]

The gas slippage effect (GSE) of coal is associated with the coalbed methane (CBM) wells' productivity. Through the helium permeability experiment of five coal samples with different vitrinite reflectance, characteristics of gas permeability variations in coal samples with different coalification degrees are analyzed, the influence of coalification degrees, coal pore structures, and different gases on GSE is revealed, and the impact of GSE on the CBM wells productivity is discussed. It indicatess that the gas permeability of coal varies with the pore pressure in a negative power function and a gas slippage coefficient of coals declines with the rise of Klinkenberg permeability by a negative power function. With the ascend of vitrinite reflectance of coal, there is an asymmetric "U-shaped" change trend in GSE. The GSE in coal with different vitrinite reflectance is mostly govern by the pore diameter distribution of coal. The slippage parameter of gas is consistent with the evolution law of coal pore structures during coal metamorphism. The slippage coefficient of different gases is obtained. On this basis, the prediction model of CBM well production considering GSE is established, and the impact degree of GSE on CBM well productivity is revealed. [ABSTRACT FROM AUTHOR]

β-Ketonitriles are an important class of compounds in organic synthesis. A new and practical cyanation of α-CF3 carbonyls with aqueous ammonia is developed. A broad spectrum of α-CF3 carbonyls, including ketones, amides and esters, could be converted to the corresponding β-ketonitriles under mild conditions. The present cyanation uses easily available materials and avoids the use of toxic cyanating reagents. [ABSTRACT FROM AUTHOR]

It is valuable and meaningful to suppress impulsive noise in system identification. Existing algorithms usually only consider impulsive noise with small frequency and amplitude. Furthermore, few researchers pay attention to the tracking performance of these algorithms. This paper builds a framework based on the deep deterministic policy gradient (DDPG) algorithm with the ability to explore and correct. The enhanced fractional derivative is introduced to further improve the performance of this reinforcement learning-based framework. Thus a fractional least mean square filter algorithm based on reinforcement learning (FrlMS) is proposed. The stability of the FrlMS algorithm is analyzed. Compared with the competing algorithms, the simulation experiments in system identification show that the FrlMS algorithm has satisfactory tracking performance in the face of impulsive noise, especially when the frequency and (or) amplitude are (is) large. [ABSTRACT FROM AUTHOR]

The ice abrasive air jet is a clean surface treatment technology, which currently has limitations such as high energy consumption, uncontrollable particle size and hardness. Realizing the instant preparation and utilization of ice particles are crucial for solving the energy consumption problem. This paper based on the icing principle of heterogeneous nucleation, proposed a new method of ice making, the heat transfer mechanism of low temperature droplets was studied, and the method was proved to be feasible. Using the FLUENT solidification and melting model combined with the VOF model to calculate the freezing process of droplets, the effects of droplet particle size, initial temperature, and wall temperature on the freezing time were analyzed, and the calculation equation of the freezing time was determined, which was corrected by the icing test results. The results showed that the outside of the droplet freezes first, the liquid–solid boundary is parabolic, and the parabolic concavity increases with time and droplet size. In the freezing process, the larger the droplet size, the longer the droplet phase transition time; the higher the droplet initial temperature, the longer it took to reach the phase transition; the higher the wall temperature, the longer the ice formation time. [ABSTRACT FROM AUTHOR]

γ-TiAl-based alloys are promising lightweight high-temperature structural materials, and the transformation from the α parent phase to γ lamellae during the cooling process has a great influence on the microstructures and mechanical properties of TiAl alloys. In this paper, an in-situ observation technique, high-temperature laser scanning confocal microscopy (HTLSCM), was utilized to investigate the continuous cooling transition (CCT) from the α phase in three compositions. The nucleation and growth behaviors of γ lamellae were studied at several moderate cooling rates. In addition, the processes of helium gas quenching for three alloys were investigated, and the massive transformation was observed in Ti–49Al. CCT diagraphs were concluded for three alloys. The Vickers hardness of TiAl alloys subjected to different cooling rates was tested, and it was found that the hardness of alloys was enhanced with increasing cooling rate due to the refinement of lamellar spacing. [Display omitted] • γ phase is observed in-situ as the primary phase in the formation of (α 2 +γ) lamellar microstructures in Ti–40Al. • γ phase massive transformation is observed in-situ in Ti–49Al on the condition of helium gas quenching. • Increasing cooling rate can enhance the nucleation rate and growth rate of γ lamellae in TiAl alloys. • The nucleation and growth of γ lamella exhibit heterogeneity associated with α grain boundary and crystal orientation. • The CCT diagraph and phase transformation path of TiAl alloys cooled from α phase are obtained. [ABSTRACT FROM AUTHOR]

With the improvement of natural gas network interconnection, the network topology becomes increasingly complex. The significance of analyzing topology is gradually becoming prominent, and a systematic analysis method is required. This paper selects two typical natural gas pipeline networks: one in Europe, and the other in North China. Based on complex network theory and the nature of natural gas pipelines, topological models for the two typical networks were established and the evaluation indexes were developed based on four factors: network type, overall topological structure characteristics, path-related topological structure characteristics, and topological structure robustness. Using these indexes, the topological structure of the two typical networks is compared and analyzed quantitatively. The comparison shows that the European network topology has more redundancy, higher transmission efficiency, and greater robustness. The topology analysis method proposed in this paper is practical and suitable for the preliminary analysis of natural gas pipeline networks. The conclusions achieved by this method can assist operators in gaining an intuitive understanding of the overall characteristics, robustness, and key features of pipeline network topology, which is useful in the implementation of hierarchical prevention and control. It also serves as a solid theoretical foundation and guidance for network expansion, interconnection construction, and precise hydraulic simulation calculation in the next stage. [ABSTRACT FROM AUTHOR]

The performance and stability of the transonic fan stage with a nonuniform inflow is a key issue in aero engine operation, and the coupling of inlet distortion and low Reynolds numbers at high altitude creates more severe challenges to aero engines. This work used computational methods to explore the performance and stability of a transonic fan stage with inlet distortion and a low Reynolds number. To investigate this issue, the transonic fan stage NASA stage 67 with a 180° total pressure distortion at a low Reynolds number was selected as the test case. Full-annulus 3D unsteady simulations were conducted to reveal the details of the flow field under coupling conditions. The computational results under different conditions were analyzed and showed that the coupling effect was not linearly stacked with single factors. The low Reynolds number in the coupling case thickened the boundary layer on the blade surface, and, on the one hand, the profile loss in the hub region increased. On the other hand, the structure of shock wave was converted in the tip region, which increased the shock loss significantly. In addition, the variation in the shock wave structure reconstructed the pressure distribution on the blade surface, allowing the fluid to migrate to the tip region, which affected the tip flow structure and ultimately delayed the stability boundary. [ABSTRACT FROM AUTHOR]

Compressor blade operating conditions and aerodynamic load change periodically owing to inlet distortion. The effects of low Re are often unavoidable when the inlet distortion is encountered in real compressor operation. Blade load distribution and internal flow field are both affected by variations in Re. In this paper, the effects of Re on the blade load distribution patterns under 60° of total pressure distortion is investigated by numerical simulation. The distortion intensity has been set to 0.05, and four cases with Reynolds number index of 1, 0.3, 0.2 and 0.1 are chosen for further analysis. The findings demonstrate that the variation of Re affects the compressor flow field mainly by modifying the aerodynamic profile of the blade, which also results in the change of the temporal and spatial distribution of the aerodynamic load. Furthermore, the aerodynamic blade profile varies significantly by Reynolds number in different spanwise regions. The blade time constant decreases in the mid-span area, while it increases in the tip. This ultimately leads to a delay in the location of the tip maximum load, changing the starting position of the induced stall. [ABSTRACT FROM AUTHOR]

A novel three-dimensional sp 3 hybrid carbon allotrope, namely C mca-C16, is predicted through structure searching within density functional theory (DFT) calculations. The structural, electronic, relative formation enthalpy and mechanical properties including bulk, shear, Young's modulus, ideal strength and Vickers' hardness are systematically investigated. The obtained results demonstrated that C mca-C16 exhibiting excellent mechanical and dynamic stability. The calculations of ideal strength indicate that the failure mode occurs along the [100] direction, with the lowest peak stress of 80.8 GPa. The theoretical hardness of C mca-C16 is calculated to be 88.6 GPa, which is comparable to that lonsdaleite (90.5 GPa) and C14-carbon (89.7 GPa), but higher than most other known carbon phases. [Display omitted] • A novel orthorhombic carbon allotrope: C mca-C16 was uncovered. • C mca-C16 is more energetically favorable than bct-C4 and M-carbon. • The hardness of C mca-C16 is predicted to be 88.4 GPa. [ABSTRACT FROM AUTHOR]

In order to tackle the environmental problems induced by Portland cement production and industrial solid wastes landfilling, this study aims to develop novel ternary cementless fly ash-based geopolymer by recycling red mud and blast furnace slag industrial solid wastes. The fresh-state properties, mechanical strength, water permeability, phase assemblage and microstructure were systematically investigated to evaluate the performance variation and reveal the hydration mechanism for geopolymers with different mixing proportions. The results showed that a higher slag content or a lower red mud content could result in the higher fluidity and shorter setting time for fresh mixture. The existence of slag promoted the transformation of N-A-S-H to C-A-S-H gel, which contributed to higher compressive strength and better resistance to water penetration. However, an excessive incorporation of 30% red mud may impede the generation of N-A-S-H gel and form more flocculent-like loose hydrates, thus to mildly degrade the mechanical strength and anti-permeability. The synergetic utilization of red much and blast furnace slag in fly ash-based geopolymer led to much less CO 2 emission compared with the condition that red much or slag was singly added, which demonstrated prominent environmental advantages for such kind of ternary cementless geopolymer with equivalent mechanical strength. [Display omitted] • A series of novel cementless geopolymers with ternary solid wastes were designed with low CO 2 emission. • Synergetic utilization of red mud and slag endowed fly ash-based geopolymer with adaptive fresh properties. • The influential mechanisms of red mud and slag on strength and permeability of geopolymer were clarified. • The hydration products and microstructure of geopolymer with red mud and slag were revealed. [ABSTRACT FROM AUTHOR]

We are entering an era that emphasizes greenness and sustainability. Based on such a philosophy, it is critical to uncover novel and original sustainable reaction modes for future green chemical syntheses. The cross-dehydrogenative coupling (CDC) reaction has thus been widely developed as one of the most sustainable and efficient synthesis strategies for constructing C–C bonds. This review summarizes the development of this field over the past 20 years, with a discussion on future trends and directions: from the original reaction model at the beginning and its development in the first decade, to extensive research in the second decade. The latest development sees the emergence of alternative forms of energy inputs (photoredox, mechano, microwave, electrochemical, continuous-flow and solar quantum dots) to facilitate CDC reactions, gradually replacing the classical form of thermal energy, which will inspire broader applications and innovations in the future. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether preoperative histogram parameters of dynamic contrast‐enhanced MRI (DCE‐MRI) can assess the expression of Ki‐67 in prostate cancer (PCa). Materials and methods: A consecutive series of 76 patients with pathology‐proven PCa who underwent routine DCE‐MRI scans were retrospectively recruited. Quantitative parameters including the volume transfer constant (Ktrans), rate contrast (Kep), extracellular‐extravascular volume fraction (Ve), and plasma volume (Vp) by outlining the three‐dimensional volume of interest (VOI) of all lesions were processed. Then, the histogram analyses of these quantitative parameters were performed. The Spearman rank correlation analysis was used to evaluate the correlation of these parameters and Ki‐67 expression of PCa. Receiver operating characteristic (ROC) curve analysis was adopted to evaluate the efficacy of these quantitative histogram parameters in identifying high Ki‐67 expression from low Ki‐67 expression of PCa. Results: Eighty‐eight PCa lesions were enrolled in this study, including 31 lesions with high Ki‐67 expression and 57 lesions with low Ki‐67 expression. The median, mean, 75th percentile, and 90th percentile derived from Ktrans and Kep had a moderately positive correlation with Ki‐67 expression (r = 0.361–0.450, p < 0.05), in which both the median and mean of Ktrans had the highest positive correlation (r = 0.450, p < 0.05). The diagnostic efficacy of the Ktrans median, mean, 75th percentile, and 90th percentile, along with the Kep‐based median and mean was assessed by the ROC curve. The area under the curve (AUC) of the mean for Ktrans was the highest (0.826). When the cut‐off of the mean for Ktrans was ≥0.47/min, its Youden index, sensitivity, and specificity were 0.625, 0.871, and 0.754, respectively. The AUC of the median of Kep was the lowest (0.772). Conclusion: The histogram of DCE‐MRI quantitative parameters is correlated with Ki‐67 expression, which has the potential to noninvasively assess the expression of Ki‐67 with patients of PCa. [ABSTRACT FROM AUTHOR]

Summary: What is known and Objective: Meropenem, a broad‐spectrum carbapenem, is frequently used to treat severe bacterial infections in critically ill children. Recommendations for meropenem doses in adult infections are available; however, few studies have been published regarding the use of meropenem in children with sepsis, especially in those receiving continuous renal replacement therapy (CRRT) and extracorporeal membrane oxygenation (ECMO). We aimed to investigate the pharmacokinetic (PK) parameters of meropenem in children with sepsis receiving extracorporeal life support (ECLS). Methods: This was a prospective observational clinical study of children with sepsis receiving ECMO or CRRT in the paediatric intensive care unit (PICU) of a children's hospital. The enrolled children received 20 mg/kg meropenem infusion over 1 hour, every 8 hours, and were grouped into children receiving ECMO, children receiving CRRT and children receiving neither ECMO nor CRRT. Plasma meropenem concentrations were determined using a validated high‐performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS). The key PK parameters were determined using the non‐compartmental approach. Results and discussion: Twenty‐seven patients were finally enrolled. The eCLCR of the CRRT group was lower than that of the ECMO group. The values of elimination half‐life (t1/2), area under the plasma concentration‐time curve (AUCtau), area under the plasma concentration‐time curve from time zero to infinity (AUC0‐∞), and total clearance (CL) in the ECMO group were not different from those of the other groups (all p > 0.05). However, the AUCtau (p = 0.0137) and AUC0‐∞ (p = 0.0234) significantly decreased after filtration through a hemofiltration membrane in patients receiving CRRT. What is new and Conclusion: No significant alterations in the PK parameters of meropenem occurred in children with sepsis administered ECMO and/or CRRT. Further investigations including PK modelling could provide evidence for appropriate meropenem dosing regimens during ECLS administration. [ABSTRACT FROM AUTHOR]

AbstractThe unique mission of the helicopter compared to the fixed-wing aircraft introduces challenges to the aerodynamic stability of the turboshaft engine. Thus, the assessment of the availability of stability margin for special operating conditions in the envelope of this equipment is required to guarantee flight safety. In this paper, a rapid nonlinear complete engine method is developed to investigate the effect of helicopter ground-effect operation and high-altitude hovering on aerodynamic stability by considering factors including inlet distortion and component matching. Research indicated that the most dangerous point of stability margin in a unique section of the flight envelope is high altitude hovering, with about a 16.7% reduction in available stability margin compared to standard ground test conditions. This paper also investigates the effects of typical helicopter ground effects on a turboshaft engine and shows that the stability margin will be reduced by a maximum of 1.43% in hovering if the influence of ground effects in the flight envelope is not considered in the design. [ABSTRACT FROM AUTHOR]

Pickering emulsion stabilized by lignin particles has many advantages such as high flexibility, natural non-toxicity, anti-oxidation, and anti-ultraviolet. In order to promote the application of industrial lignin in the field of Pickering emulsions, this study has done comparatively systematic and basic research on Pickering emulsions stabilized by lignin particles. The emulsification effects of lignin particles on cyclohexane and n-decanol which have opposite polarity were compared firstly under different oil-water ratios. It was found that stable emulsions formed when the three-phase contact angle of oil/water/lignin was closer to 90°. The weakly polar cyclohexane could be well-emulsified by lignin particles, while the strong polar n-decanol could not. Cyclohexane was used as the oil phase to discuss the emulsification ability of lignin particles under different concentrations or with different particle sizes. The results show increasing the concentration of lignin particles or reducing the particle size can improve the emulsification performance. [ABSTRACT FROM AUTHOR]

One of the main techniques for the exploitation of shale oil and gas is hydraulic fracturing, and the fracturing fluid (slick water) may interact with minerals during the fracturing process, which has a significant effect on the shale pore structure. In this study, the pore structure and fluid distribution of shale samples were analyzed by utilizing low-pressure liquid nitrogen adsorption (LP-N2GA) and nuclear magnetic resonance (NMR). The fractal analysis showed that the pore structure of the sample was strongly heterogeneous. It was also found that the effect of slick water on pore structure can be attributed to two phenomena: the swelling of clay minerals and the dissolution of carbonate minerals. The swelling and dissolution of minerals can exist at the same time, and the strength of them at different soaking times is different, leading to the changes in specific surface area and pore size. After the samples were soaked in the slick water for two days, the contact angle reached the minimum value (below 8°), which means the sample is strongly hydrophilic; then the contact angle increased to above 38° with longer soaking times. The connected pore space in the shale matrix is enlarged by the soaking processing. Therefore, an in-depth understanding of the interaction between the fracking fluid and shale is essential to deepen our understanding of changes in the pore structure in the reservoir and the long-term productivity of shale gas. [ABSTRACT FROM AUTHOR]

Amplitude, an important electromagnetic wave attribute, is considered as a useful parameter to describe the energy attenuation of electromagnetic wave. In this study, SIR-3000 Radar Equipment was employed to investigate the amplitude of electromagnetic wave in medium sandstone with different water content and depth. Results suggest that, with same water content, the decreasing of electromagnetic wave energy with increasing depth can be described by maximum peak amplitude, while, the decreasing of electromagnetic wave energy with increasing water content at certain depth can be described by average amplitude. In addition, energy of electromagnetic wave is negatively correlated to the dielectric constant because of the positive correlation between water content and dielectric constant. This study can provide significant information to the water measurement in aeration zone. [ABSTRACT FROM AUTHOR]

Low-cost modified rubber powder DBR elastic particles with good temperature and salt resistance were selected to investigate the plugging–matching relationship between the elastic particles and formation pore throats. The elastic deformation coefficient of the particles was measured using a custom-built uniaxial compression experimental device. Based on the ideal model and arrangement of spherical particles, a calculation method for the pore throat size was determined according to the statistical results of pore size measurements in the simulated formations (sand packs). The injection properties of DBR particles with different diameters in different permeability simulated formations were studied using a sand-filled tube displacement device. Through comprehensive analysis, the injection pressure fluctuation frequency, injection surface filter cake situation, particle entry depth, and plugging pressure, it was found that the elastic particle plugging matching coefficient (defined as the particle to pore through diameter ratio) range was 0.21–1.10 at different particle injection concentration(≤5wt%), and it is further proposed that the matching coefficient for elastic particles can be converted to that for rigid particles by dividing through by the elastic deformation coefficient, which may prove useful in guiding profile control and water plugging operations in the field. Finally, the different stages in the plugging and migration mechanisms of elastic particles in formation pore throats were illustrated using a visual variable diameter tube model. The model clearly showed that particle backflow disturbance is an adverse factor affecting particle plugging. [ABSTRACT FROM AUTHOR]

• The dynamic counter-imbibition processes along the core samples were monitored in-time using low-field NMR technique. • The imbibition front and oil recoveries within individual layers along the core sample were determined. • Nanofluid advanced farther than DI water along the core sample during the counter-imbibition process. • The nanofluid on interfacial properties and rock pore structure are the dominant mechanism for nanofluid in EOR. Counter-current imbibition behavior is an important mechanism for exploiting oil recovery during shut-in periods after hydraulic fracturing in tight oil reservoirs. However, most researches mainly focused on imbibition recovery and its influencing factors in tight oil reservoirs, while experimental investigations to quantitatively characterize the imbibition distance is still inadequate. In this work, counter-current imbibition experiments under one end open (OEO) boundary condition were conducted, and the dynamic imbibition process in porous media were monitored in real-time by nuclear magnetic resonance (NMR) pulse sequences and NMR imaging to quantify the range of counter-current imbibition and the reduction of oil saturation in-situ. In addition, a one-dimensional (1D) imbibition numerical model with OEO boundary condition at core scale was developed, and the influencing factors on oil production was further discussed in detail. The experimental results illustrated that the overall oil recoveries of nanofluid and deionized (DI) water were 25.37 % and 5.19 %, respectively. Moreover, the advancing distance of nanofluid was 4.44 cm, while DI water advanced only 2.38 cm along the core sample. Nanofluid considerably reduced residual oil saturation and increased movable fluid saturation, making the crude oil to be highly mobilized in micro- and mesopores. The simulated results well verified the counter-current imbibition experimental data, and indicated that the influences of core permeability and fluid viscosity on imbibition performances were more significant than that of core length. The purpose of this work is to provide a new method to determine the extent of counter-current imbibition. [ABSTRACT FROM AUTHOR]

Low-permeability oil reservoirs account for more than two-thirds of China's proven reserves, and most of them are multilayered; the traditional sweet spots focus on single-layered reservoirs. The sweet spots of low-permeability reservoirs have two meanings: the geologically superior reservoir and the beneficial development of the reservoir. In this study, a concept of reservoir stratification coefficient is proposed to evaluate the characteristics of multilayered reservoirs, and three indicators are proposed, namely, reservoir stratification coefficient, energy storage coefficient, and stratigraphic coefficient, as the indicators of sweet spots of multilayered reservoirs. The three indicators are combined into a single indicator using a weighted approach, and the sweet spots can be identified based on the combined indicator. The Xiliu A area of the North China oilfield was selected for a case study. According to the structural, sedimentary, and reservoir characteristics of the block, combined with the development and production conditions, the Sha 3 Member I oil group was selected as the study object of sweet spots of the low-permeability reservoir. The results show that the reservoir stratification coefficient, energy storage coefficient, and stratigraphic coefficient proposed in this study are effective indicators for the preferential selection of sweet spots, which can reflect the longitudinal heterogeneity, energy storage size, and flow capacity of multilayered reservoirs. After a comparative analysis with actual blocks, it was found that the results obtained using the method are consistent with the actual capacity of the reservoir. The production capacity is high. The evaluation effect is ideal, and the applicability is good. Thus, this study provides a new technical method for the evaluation of similar multilayered reservoirs. The findings of this study can help for a better understanding of the development and production conditions and optimization basis of low-permeability reservoirs. [ABSTRACT FROM AUTHOR]

The concentrations of ambient fine particulate matter (PM2.5) and its compositions in urban Taiyuan, China during a typical winter and summer time period in 2017 were measured to investigate the pollution characteristics, source apportionment and health risks assessment of PM2.5 pollution. The results demonstrated that the mean daily mass concentration of PM2.5 in winter (102.6 ± 6.2 μg/m3) was higher than that in summer (65.0 ± 17.2 μg/m3) during sampling. The relatively high concentrations of heavy metals (Zn, Pb, Cu, As, Ni, Cr and Cd), anion (SO42−, NO3−, Cl− and F−) and high-molecular-weight PAHs in PM2.5 were observed. The enrichment factors (EFs) values, special diagnostic ratios like ratios of NO3−/SO42− and individual PAHs concentration ratio showed that coal combustion and vehicle emissions were the major sources of PM2.5 pollution. Health risk assessment illustrated that mean hazard indices for non-cancer and cancer risk of all analyzed metals were within the safe range. However, inhalation exposure to PM2.5-bound PAHs had carcinogenic risk, while not indicating non-carcinogenic risk. Taken together, although PM2.5 pollution was alleviated to some extent, PM2.5 pollution in 2017 was still serious and PM2.5 was mainly originated from coal burning, especially, in which PM2.5-bound PAHs in Taiyuan may pose a potential health risk. [ABSTRACT FROM AUTHOR]

In this paper, we study the quasi-shadowing property for quasi-partially hyperbolic δ -pseudo-orbit made by quasi-partially hyperbolic strings. We also investigate the corresponding L p , limit and asymptotic quasi-shadowing properties. As an application, we prove that the set of points with periodic center leaves is dense in the non-wondering set for some partially hyperbolic flows. [ABSTRACT FROM AUTHOR]

Meiotic recombination is a key step in meiosis because it facilitates the pairing of homologous chromosomes and generates new combinations of genetic alleles, which results in the diversification of extant eukaryotes. Spo11, a meiosis‐specific protein, catalyses the formation of double‐strand breaks (DSBs) and initiates meiotic recombination in a wide variety of organisms, but the exact function of spo11 in the formation of gametes needs further study in fish. In this study, we knocked out the spo11 gene in zebrafish using CRISPR/Cas9 technology. Sexually dimorphic reproductive defects were found in the spo11‐mutated zebrafish. The spo11‐/‐ males were completely sterile, but spo11‐/‐ females were fertile and there was no significant difference in relative fecundity and fertilisation rates compared with WT females; however, the offspring of spo11‐/‐ females had severe developmental defects. In addition, we found that spo11 was expressed only in gonad tissue, and the level of expression in the testes was much higher than in the ovaries. Surprisingly, spo11 was also expressed in zebrafish embryos, especially at the dome stage. We compared amino acid sequences of Spo11 in ten different fish and found that Spo11 was highly conserved. Importantly, the results established zebrafish as a vertebrate model for understanding multiple roles of spo11 in meiosis. [ABSTRACT FROM AUTHOR]

When a conventional waterflooding characteristic curve (WFCC) is used to predict cumulative oil production at a certain stage, the curve depends on the predicted water cut at the predicted cutoff point, but forecasting the water cut is very difficult. For the reservoirs whose pressure is maintained by water injection, based on the water-oil phase seepage theory and the principle of material balance, the equations relating the cumulative oil production and cumulative water injection at the moderately high water cut stage and the ultrahigh water cut stage are derived and termed the Yuan-A and Yuan-B curves, respectively. And then, we theoretically analyze the causes of the prediction errors of cumulative oil production by the Yuan-A curve and give suggestions. In addition, at the ultrahigh water cut stage, the Yuan-B water cut prediction formula is established, which can predict the water cut according to the cumulative water injection and solve the difficult problem of water cut prediction. The application results show Yuan-A and Yuan-B curves are applied to forecast oil production based on cumulative water injection data obtained by the balance of injection and production, avoiding reliance on the water cut forecast and solving the problems of predicting the cumulative oil production of producers or reservoirs that have not yet shown the decline rule. Furthermore, the formulas are simple and convenient, providing certain guiding significance for the prediction of cumulative oil production and water cut for the same reservoir types. [ABSTRACT FROM AUTHOR]

The optimization of oil field development scheme considering the uncertainty of reservoir model is a challenging and difficult problem in reservoir engineering design. The most common method used in this regard is to generate multiple models based on statistical analysis of uncertain reservoir parameters and requires a large number of simulations to efficiently handle all uncertainties, thus requiring a huge amount of computational power. In order to reduce the computational burden, a method which combines reservoir simulation, an economic model, polynomial chaos expansion with response surface methodology, and Levy flight particle swarm optimization (LFPSO) algorithm is proposed to determine the optimal injection-production parameters with reservoir uncertainties at a reasonable computational cost. This approach is applied to a five-spot well pattern optimization design for obtaining the optimal parameters, including oil-water well distance, injection rate, and bottom hole pressure, while considering the uncertainties of porosity, permeability, and relative permeability. The results of the case study indicated that the integrated approach is practical and efficient for performing reservoir optimization with uncertain reservoir parameters. [ABSTRACT FROM AUTHOR]

Guerbet amine-oxide was synthesized by using Guerbet acid, N,N′-diethyl-1,3-propanediamine and hydrogen peroxide. Its structure was confirmed by FT-IR spectra and mass spectra. The critical micelle concentration (CMC) and the interfacial tension between the crude oil and water were measured. The results showed that the CMC of the Guerbet amine-oxide is 2.14 × 10−5 mol/L and the interfacial tension could be lowered to ultralow levels. The core flood test showed that the surfactant and polymer binary system could increase oil recovery by 24.7% above the water flood. [ABSTRACT FROM AUTHOR]

• PM 2.5 triggers mitochondrial morphological and function damage of H9c2 cells. • MiR-421/SIRT3 pathway regulates cardiac mitochondrial dynamics imbalance after PM 2.5 treatment. • MiR-421 inhibitor and resveratrol protect PM 2.5 -induced mitochondrial damage. Fine particulate matter (PM 2.5) exposure is associated with cardiovascular disease (CVD) morbidity and mortality. Mitochondria are sensitive targets of PM 2.5 , and mitochondrial dysfunction is closely related to the occurrence of CVD. The epigenetic mechanism of PM 2.5 -triggered mitochondrial injury of cardiomyocytes is unclear. This study focused on the miR-421/SIRT3 signaling pathway to investigate the regulatory mechanism in cardiac mitochondrial dynamics imbalance in rat H9c2 cells induced by PM 2.5. Results illustrated that PM 2.5 impaired mitochondrial function and caused dynamics homeostasis imbalance. Besides, PM 2.5 up-regulated miR-421 and down-regulated SIRT3 gene expression, along with decreasing p-FOXO3a (SIRT3 downstream target gene) and p-Parkin expression and triggering abnormal expression of fusion gene OPA1 and fission gene Drp1. Further, miR-421 inhibitor (miR-421i) and resveratrol significantly elevated the SIRT3 levels in H9c2 cells after PM 2.5 exposure and mediated the expression of SOD2, OPA1 and Drp1, restoring the mitochondrial morphology and function. It suggests that miR-421/SIRT3 pathway plays an epigenetic regulatory role in mitochondrial damage induced by PM 2.5 and that miR-421i and resveratrol exert protective effects against PM 2.5 -incurred cardiotoxicity. [Display omitted] [ABSTRACT FROM AUTHOR]

Compared to conventional Pylon-mounted engines, a 5-15% reduction in aircraft fuel consumption is possible with the use of Boundary Layer Ingestion (BLI) propulsion system. However, this type of propulsion system uses a fan that has to operate under continuous inlet distortion and over a wide range of altitude within the flight envelope, which forces researchers to consider the Re effects on the BLI distorted fan stall. For typical spike-type stall, tip leakage flow (TLF) contributes crucially to its generation. Thus, this paper aims to investigate the Re effects on the tip unsteady flow structures under the circumferential distorted inflow near the stall point. In this study, a full-annulus 3D steady/unsteady CFD calculation has been employed to calculate the performance of the NASA 67 transonic fan stage with a 60-deg circumferential distortion at different Re. The results show that the Re effects change the location of peak amplitude of blade tip unsteady flow, without altering the frequency properties. For the further study of the Re effects on the tip unsteady flow, time series analyses of detailed flow structure features and tip leakage vortex (TLV) evolution are performed. At low Re, the angle between the TLF and the axis increases from 77 to 81 deg by comparing the shock structure at 0.99 span, and the secondary flow is enhanced with a marked tendency of blade leading edge spillage. The results indicate that TLV has greater size and strength for low Re condition, and the TLV is more pronounced in the distortion sector than it in the clean sector. Further analysis reveals that the change of shock structure affects the periodic variation in rotor differential pressure on the both surfaces, enhancing the circumferential momentum of TLF near the leading edge, which is the major contributor for changing the vortex structure and causing the stall advance in low Re condition. [ABSTRACT FROM AUTHOR]

Epilepsy is the most common chronic neurological disorder, affecting ~70 million individuals worldwide. However, approximately one-third of the patients are refractory to epilepsy medication. Of note, 100% of patients with genetic epilepsy who are resistant to the traditional drug, valproic acid (VPA), are also refractory to the other anti-epileptic drugs. The aim of the present study was to compare the transcriptomes in VPA responders and non-responders, to explore the mechanism of action of VPA and identify possible biomarkers to predict VPA resistance. Thus, RNA-seq was employed for transcriptomic analysis, differentially expressed genes (DEGs) were analyzed using Cuffdiff software and the DAVID database was used to infer the functions of the DEGs. A protein-protein interaction network was obtained using STRING and visualized with Cytoscape. A total of 389 DEGs between VPA-responsive and non-responsive pediatric patients were identified. Of these genes, 227 were upregulated and 162 were downregulated. The upregulated DEGs were largely associated with cytokines, chemokines and chemokine receptor-binding factors, whereas the downregulated DEGs were associated with cation channels, iron ion binding proteins, and immunoglobulin E receptors. In the pathway analysis, the toll-like receptor signaling pathway, pathways in cancer, and cytokine-cytokine receptor interaction were mostly enriched by the DEGs. Furthermore, three modules were identified by protein-protein interaction analysis, and the potential hub genes, chemokine (C-C motif) ligand 3 and 4, chemokine (C-X-C motif) ligand 9, tumor necrosis factor-α and interleukin-1β, which are known to be closely associated with epilepsy, were identified. These specific chemokines may participate in processes associated with VPA resistance and may be potential biomarkers for monitoring the efficacy of VPA. [ABSTRACT FROM AUTHOR]

Relative permeability stress sensitivity studies reported in literature do not have a common conclusion with regards to end point saturations and their respective relative permeabilities. Moreover, there is lack of experimental results on stress sensitivity of pore fluid distribution, which is a key parameter for the behavior of relative permeability curves. This study extended core homogeneity to include similar porosity, permeability and NMR T 2 distribution as well as examined NMR T 2 distribution behavior with stress on artificial sandstone cores and the results used in explaining relative permeability stress sensitivity under net confining stresses of 5, 15 and 25 MPa. The effect of stress on displacement efficiency was also investigated. The bulk volume irreducible (BVI), which is the fraction of the bulk volume containing irreducible water, generally increased with stress. Meanwhile the free fluid index (FFI), which is the fraction of the bilk volume responsible for fluid flow, decreased with increased stress. NMR irreducible water saturation and irreducible water saturation obtained from relative permeability experiments both increased with stress. Irreducible water saturation was strongly related to the behavior BVI stress sensitivity. Residual oil saturation increased with increase in stress as a result of reductions in FFI pore volume. End-point oil relative permeability had a significant decrement with stress while water end-point relative permeability had a negligible decrement. The significant reduction in end-point oil relative permeability was due to reductions in pore radius evident in a corresponding reduction in FFI. Displacement efficiency decreased with increased stress indicating lower oil recovery on microscopic scale but end-point mobility ratio increased as stress increased. Relative permeability stress sensitivity could be tied to changes in BVI and FFI of NMR T 2 distribution when changes in stress occur in petroleum reservoirs. • NMR T 2 distribution was employed to study relative permeability stress sensitivity. • BVI and FFI increase and decrease, respectively with increase in stress. • Sensitivity of BVI causes changes in irreducible water saturation. [ABSTRACT FROM AUTHOR]

Advanced production decline analysis methods have become more economic and efficient options due to technical and time limitations of well-testing operations in shale gas reservoirs. By normalizing rate with material balance pseudo-time, Blasingame type decline analysis can be applied to variable rate/variable pressure drop system, making the methodology more widely applicable. Blasingame decline analysis of variable rate/variable pressure drop case for multi-fractured horizontal well (MFHW) in shale has been less investigated, because of multi-scale storage spaces and multi-flow mechanisms. This article presents a semi-analytical Blasingame decline analysis model incorporating multi-flow mechanisms with shale's modified material balance pseudo-time. Laplace transformation, point source function, numerical discrete method, perturbation method, and Gaussian elimination method were employed to solve the mathematical problem caused by multi-flow mechanisms. Besides, the material balance pseudo-time was modified by considering adsorption and desorption. In this study, a workflow to investigate the effects of properties of hydraulic fracture (fracture half-length, number of fractures and fracture spacing) and multi-flow mechanisms (diffusion and desorption) on production decline behaviors through diagnostic Blasingame type curves is proposed. The results indicate that productivity is greater with a larger scale of fracture treatment, and better desorption of adsorbed gas is also beneficial to production. The decline rates affected by the fracture treatment scale and supplement capacity show two opposite trends, which is caused by interference between the fractures and boundary, respectively. Except that the data in the diffusion early flow period do not match very well, because the use of diffusion coefficient as a constant, the good fitting results on the whole verifies the model's validity and reliability. • A new Blasingame decline model of shale accommodating multi-mechanisms is established. • Effects of fracture and flow mechanism on production behaviors are analyzed. • Simulated result matches well with rate data. • Considering diffusivity as a constant may result in poor fitting result. [ABSTRACT FROM AUTHOR]

Hydraulically fractured horizontal well technologies, which combine hydraulically fractured technology with horizontal well technology, is widely used to enhance oil recovery in tight reservoir production. Although there are many advantages to this method, it requires more investment in drilling and completion. Most academic literature to date has treated the optimization of well placement and fracturing as two separate problems. Computationally expensive numerical simulation techniques are often involved both in well placement and fracturing design optimization processes, but only suboptimal solutions are achievable. In order to achieve co-optimization for horizontal well placement and fracturing, an optimal model has been constructed, with an objective function targeted at maximizing the net present value (NPV), which is a function of location, direction and length of a new horizontal well, the number of fractures, half-length of the fracture etc. Due to the large number of optimization variables, investigating the impacts of horizontal well parameters on the objective function must utilize repetitive runs of numerical simulations involving large computation times for evaluating possible well placement and fracturing scenarios. Aiming to address this challenge, a new method, called the Multipoint Adaptive Gaussian Process Surrogate Model with Important Design Domain (MAGPSM-IDD), is proposed. Then MAGPSM-IDD were applied to a synthetic field and a real reservoir, and our results showed that MAGPSM-IDD could obtain better results with higher efficiency than the popular optimization method, Hybrid Genetic Algorithm (HGA). • An integrated optimization design method for horizontal well placement and fracturing is constructed. • A multipoint adaptive surrogate model with important design domain is proposed to obtain the optimal design. • MAGPSM-IDD method converges faster and achieves better NPV values than PSO, GA and HGA. [ABSTRACT FROM AUTHOR]

Abstract A reduced/selective integration finite element method coupled with a gradient flow method is introduced for the cavitation computation in nearly incompressible nonlinear elasticity. Numerical experiments show that, for the iso-parametric biquadratic finite element approximation of the displacement field, the method is locking free and efficient for the nearly incompressible cavitation computation and has the same optimal convergence rates as in the compressible case for the elastic energy as well as the deformation and stress field, if and only if the reduced integration is applied to the bulk energy term using no more than 2 Gaussian quadrature nodes in each dimension. [ABSTRACT FROM AUTHOR]

Silica nanofluids have proven to be successful in improving hydrocarbon recovery in the petroleum industry, and increased demand for hydrocarbons has necessitated its application in low-permeability reservoirs. In recent times, surface coating of nanoparticles has been employed to reduce its retention in porous media, but this does not entirely eliminate nanoparticle attachment to pore walls. Knowledge of changes that occur in pore wall and structure such as specific surface area (SSA), pore size distribution and total pore volume (TPV) would be useful in understanding retention mechanisms. This study used nitrogen adsorption technique in studying changes in pore structure due to silica nanofluid treatment. The Brunauer–Emmett–Teller theory and Barrett–Joyner–Halenda adsorption model were used in determining SSAs and TPVs, respectively. SSA, adsorbability and TPV increased in treated samples compared to untreated samples and the rates of change increased with treatment time due to extra pores induced by nanoparticle coagulation. Percent changes in TPV matched closely with SSA and was responsible for increments in the latter. Scanning electron micrographs confirmed coagulation of nanoparticles which increased with treatment time and introduced pseudo-pores on pore walls, resulting in increase in TPV. Increase in differential pore volume was observed for the entire studied range of 2–100 nm except for 3–4 nm which showed no changes in all samples. Severity of differential pore volume increased with treatment time. This study provides insights into nanoscopic changes that occur on pore walls and structure when employing silica nanoparticles in improving hydrocarbon recovery in low-permeability hydrocarbon reservoirs. [ABSTRACT FROM AUTHOR]

Abstract Complement factor 5a is a potent proinflammatory mediator that contributes to the pathogenesis of numerous inflammatory diseases. Protein-based C5a inhibitors have proven to be clinically valuable. Aptamers, which are oligonucleic acid chains or polypeptides, can bind to target molecules and hence have the potential to be used for detection and blockade of targets. Here, we describe the discovery that the single-stranded DNA aptamer S1 can bind specifically to swine C5a, which can then be quickly selected for with capillary electrophoresis for high-throughput sequencing. Aptamer S1 bound specifically to swine C5a with a dissociation constant of 4 μM as measured by surface plasmon resonance (SPR). Moreover, aptamer S1 inhibited C5a-induced chemotaxis of neutrophils in vitro. Our study suggests that the S1 aptamer has great potential to be a key structure in the development of effective therapeutic agents against inflammatory diseases. Highlights • A DNA aptamer was screened by CE and HTS. • The aptamer could bind C5a protein and inhibit its activity. [ABSTRACT FROM AUTHOR]

Abstract Spontaneous imbibition is an important mechanism governing the tight reservoir production performance, especially in the early stage of production after hydraulic fracturing. The microscopic pore structure of reservoirs is an important factor affecting imbibition. In this study, high-pressure mercury injection (HPMI), rate-controlled mercury injection, and low-temperature nitrogen adsorption (LP-N 2 GA) were preformed to study pore structure characteristics and fluid distribution in samples from the Ordos Basin, China. Nuclear magnetic resonance (NMR) and imbibition experiments were used to investigate the fluid distribution in porous media during imbibition. The porosity of samples ranges from 11.378% to 12.356%, with an average of 12.034%. The permeability of samples ranges from 0.034 mD to 0.056 mD, with an average of 0.048 mD. Results show that the recovery ranges from 68% to 94.81%, with an average of 81.09%. The reservoir is dominated by open flat slit micropores and mesopores. Sample pore volume ranges from 0.0155 ml/g to 0.0193 ml/g, with an average of 0.01687 ml/g. Micropores and mesopores less than 50 nm provide most of the pore volume. Pore radius and pore-throat ratio were obtained from experiments. Imbibition occurs primarily in pores ranging from 0.1 μm to 1 μm in radius, followed by pores ranging from 1 μm to 10 μm. The effects of porosity, permeability, average pore radius, average throat radius, average pore-throat ratio, specific surface area, and pore volume on imbibition recovery were statistically analyzed. Grey relational analysis was applied to sequence the imbibition influencing factors and determine the most influential factor. Results demonstrate that imbibition recovery is the most affected by average pore radius, followed by permeability, porosity, average pore-throat ratio, median radius, average throat radius, and specific surface area. Highlights • Study on the characteristics of microscopic pore structure with different methods. • Imbibition test and NMR technology are used to investigate the fluid distribution. • The effects of different factors on imbibition recovery are statistically analyzed. • Grey relational analysis is applied to sequence the imbibition influence factors. • Imbibition recovery is the most affected by average pore radius. [ABSTRACT FROM AUTHOR]

Abstract This study explores the neuro-protective effects of Amanita caesarea polysaccharides (ACPS), obtained by 80% alcohol precipitation of water extract and purified using a DEAE-52 cellulose anion exchange column, related to antioxidant activity. A 3-h pre-treatment of ACPS prior to l ‑glutamic acid (l ‑Glu) co-exposure reversed the decreased cell viability, inhibited apoptosis, suppressed the accumulation of intracellular reactive oxygen species and restored mitochondrial membrane potential in HT22 cells. Compared to l ‑Glu-exposed cells, ACPS enhanced the nuclear levels of NF-E2p45-related factor 2 (Nrf2), reduced the cytoplasmic levels of Nrf2 and cytochrome C, suppressed the expression of Kelch-like ECH-associated protein 1, and enhanced the expression of heme oxygenase‑1, superoxide dismutase 1 and cysteine ligase catalytic subunit. In a d ‑galactose and aluminum trichloride Alzheimer's disease (AD) mouse model, 42-day administration of ACPS improved the abnormal behaviors. ACPS suppressed the deposition of β‑amyloid peptide in the brain and ameliorated oxidative stress via modulating the levels of related enzymes. ACPS improved the functioning of the central cholinergic system, as indicated by an increase in acetylcholine and choline acetyltransferase concentrations, and reduced acetylcholine esterase levels in the serum, hypothalamus and cerebral cortex. Our data suggest that ACPS may be a promising candidate for the treatment of AD. [ABSTRACT FROM AUTHOR]

A numerical study on a new bifurcation phenomenon in multi-void growth is carried out for a 2-D problem in nonlinear elasticity, where the reference configuration is y-axisymmetric with two pre-existing small voids. The numerical experiments show that, under large radially-symmetric displacement boundary conditions, other than the y-axisymmetric equilibrium solution one would normally expect, there are two energetically more favorable non-y-axisymmetric equilibrium solutions in which the growth of one void is overwhelmingly dominant. The relationships between the critical bifurcation boundary displacement and the compressibility of the material as well as some geometric parameters are illustrated by numerical results. The numerical experiments also show that the existence of the secondary bifurcation will effectively expedite the onset of fractures. [ABSTRACT FROM AUTHOR]

A dynamic cavity growth problem in an isotropic compressible nonlinear hyper-elastic material subject to a gradually applied traction is numerically studied. The effects of three parameters, namely the material mass density, the maximum traction, and the loading rate, on the evolution of the cavity radius, especially the maximum cavity radius, are investigated. The numerical results show that, while both the inertia and loading rate have only marginal effect on the onset of cavitation, they do significantly affect the maximum cavity radius. Furthermore, the applied traction eventually leads to a periodic oscillatory cavity growth, and a square root power law for the vibration period as a function of the material mass density is found to hold. [ABSTRACT FROM AUTHOR]

Abstract The secondary loss is the primary factor limiting the performance of highly loaded compressors. As inspired by the transonic area rule used in optimization of airplane fuselage, considering the similarities of the blockage effect induced by wing to fuselage and the blockage induced by blade to flow channel, the idea of using the transonic area rule method in compressor hub profile modification has been proposed and discussed. Some related analyses are investigated due to the failure of a direct application of the transonic area rule, which includes flow field analyses, the study of related parameters and a sensitivity evaluation of eleven control parameters on the adiabatic efficiency of the compressor. Then, two parameters (rotor maximum concave displacement ratio Δ Z ‾ R and magnification ratio of rotor hub leading edge l ¯ 1 R) which have great influence on the compressor efficiency are chosen to modify the transonic area rule and to establish a new optimization guideline in the optimization of compressor hub profile. After all, the developed optimization method is applied to the first stage of a four-stage embedded compressor with an achievement of 0.97% peak efficiency rise without any penalty of total pressure ratio. Based on the numerical results, the main reasons for the peak efficiency rise are also presented and discussed. [ABSTRACT FROM AUTHOR]

While studies on the stress sensitivity of relative permeability using conventional fluids have varying and inconclusive results, the effect of stress on relative permeability using nanofluids has not been reported. In this study, the effect of net effective stress on relative permeability and two-phase flow parameters using conventional and nanofluid was investigated. Nanoparticle retention in pores was examined by changes in nuclear magnetic resonance transverse relaxation time distribution. Nanoparticle deposition affected big pores more than small pores. As net effective stress was increased during water flooding, end-point oil and water saturations increased and end-point oil relative permeability decreased. Nanofluid-oil relative permeability showed contrasting results depending on whether the sample had adsorbed nanoparticles prior to relative permeability measurements. For the sample that had adsorbed nanoparticles prior to subsequent stress increments, the effect of stress was dominated by the effect of nanoparticle adsorption. However, the effect of stress took precedence over nanoparticle adsorption in samples that had no nanoparticle deposition prior to relative permeability experiments. A comparison of water-oil and nanofluid-oil relative permeabilities showed similar initial water saturations and end-point oil relative permeability changes but differing residual oil saturations and end-point water relative permeability. Mobility ratio increased in water flooding as stress increased but decreased after an initial increase in nanofluid flooding. Displacement efficiency decreased with increased stress for both water and nanofluid flooding. The results provide insights into the effect of stress on relative permeability using conventional fluids and silica nanofluid. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The sulfonylation-peroxidation of alkenes is developed. • β-Sulfonyl peroxides were synthesized by the three-component peroxidation of alkenes. • β-Sulfonyl peroxides were converted into sulfone derivatives under mild conditions. Abstract The sulfonylation-peroxidation of alkenes with sulfonyl hydrazides and T-hydro was developed. The Ag-catalyzed three-component peroxidation provides a method for synthesis of a variety of β-sulfonyl peroxides, which could be converted into various sulfone derivatives. [ABSTRACT FROM AUTHOR]

Several multiferroic AMnO3 (A = Gd, Tb, Dy) particles were synthesized by microwave-assisted acrylamide gel route. The influence of A-site cation on the phase purity, surface morphologies, and optical and magnetic properties of the as-prepared multiferroic AMnO3 (A = Gd, Tb, Dy) particles was investigated. X-ray diffraction pattern, Fourier transform infrared spectroscopy, and Raman spectroscopy confirm the pure phase of the AMnO3 (A = Gd, Tb, Dy) particles exhibits an orthorhombic perovskite structure. Scanning electron microscopy (SEM) observation indicates that the surface morphology of AMnO3 (A = Gd, Tb, Dy) particles is significantly dependent on the A-site cation. The particle size of AMnO3 (A = Gd, Tb, Dy) particles increases with the increasing atomic number of A-site cation The optical band gap values of AMnO3 (A = Gd, Tb, Dy) particles decrease with an increase in the atomic number of A-site cation. Magnetization measurements show that these AMnO3 (A = Gd, Tb, Dy) particles exhibit magnetic ordering at low temperatures. [ABSTRACT FROM AUTHOR]

[Corrigendum] Neuroprotective effect of emodin against Alzheimer's disease via Nrf2 signaling in U251 cells and APP/PS1 mice Mol Med Rep 23: 108, 2021; DOI: 10.3892/mmr.2020.11747 Subsequently to the publication of this paper, an interested reader drew to the authors' attention that the lower left panel of Fig. (A) Emodin decreased the escape latency time of APP/PS1 mice during the Morris water maze test. (B) Emodin decreased the time spent by APP/PS1 mice in the central area during the open field test. [Extracted from the article]

A new method for the synthesis of 4‐cyano‐1,2,3‐triazoles is developed using a three‐component strategy. The cyano group is generated in situ by the reaction of 2,2,2‐trifluoroethyl ketone and aqueous ammonia. The one‐pot protocol allows the synthesis of 4‐cyano‐1,2,3‐triazoles under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract: Hard carbons (HCs) possess high lithium/sodium storage capacities, which however suffer from low electric conductivity and poor ion diffusion kinetics. An efficient structure design with appropriate heteroatoms doping and optimized graphitic/defective degree is highly desired to tackle these problems. This work reports a new design of N‐doped HC nanoshells (N‐GCNs) with homogeneous defective nanographite domains, fabricated through the prechelation between Ni2+ and chitosan and subsequent catalyst confined graphitization. The as‐prepared N‐GCNs deliver a high reversible lithium storage capacity of 1253 mA h g−1, with outstanding rate performance (175 mA h g−1 at a high rate of 20 A g−1) and good cycling stability, which outperforms most state‐of‐the‐art HCs. Meanwhile, a high reversible sodium storage capacity of 325 mA h g−1 is also obtained, which stabilizes at 174 mA h g−1 after 200 cycles. Density functional theory calculations are performed to uncover the coupling effect between heteroatom‐doping and the defective nanographitic domains down to the atomic scale. The in situ Raman analysis reveals the “adsorption mechanism” for sodium storage and the “adsorption–intercalation mechanism” for lithium storage of N‐GCNs. [ABSTRACT FROM AUTHOR]

Abstract: Hard carbons (HCs) possess high lithium/sodium storage capacities, which however suffer from low electric conductivity and poor ion diffusion kinetics. An efficient structure design with appropriate heteroatoms doping and optimized graphitic/defective degree is highly desired to tackle these problems. This work reports a new design of N‐doped HC nanoshells (N‐GCNs) with homogeneous defective nanographite domains, fabricated through the prechelation between Ni2+ and chitosan and subsequent catalyst confined graphitization. The as‐prepared N‐GCNs deliver a high reversible lithium storage capacity of 1253 mA h g−1, with outstanding rate performance (175 mA h g−1 at a high rate of 20 A g−1) and good cycling stability, which outperforms most state‐of‐the‐art HCs. Meanwhile, a high reversible sodium storage capacity of 325 mA h g−1 is also obtained, which stabilizes at 174 mA h g−1 after 200 cycles. Density functional theory calculations are performed to uncover the coupling effect between heteroatom‐doping and the defective nanographitic domains down to the atomic scale. The in situ Raman analysis reveals the “adsorption mechanism” for sodium storage and the “adsorption–intercalation mechanism” for lithium storage of N‐GCNs. [ABSTRACT FROM AUTHOR]

The approximation properties of a quadratic iso-parametric finite element method for a typical cavitation problem in nonlinear elasticity in two dimensions are analyzed. More precisely, (1) the finite element interpolation errors are established in terms of the mesh parameters; (2) a mesh distribution strategy based on an error equi-distribution principle is given; (3) the convergence of finite element cavity solutions is proved. Numerical experiments show that, in fact, the optimal convergence rate can be achieved by the numerical cavity solutions. [ABSTRACT FROM AUTHOR]

A Fourier-Chebyshev spectral method is proposed in this paper for solving the cavitation problem in nonlinear elasticity. The interpolation error for the cavitation solution is analyzed, the elastic energy error estimate for the discrete cavitation solution is obtained, and the convergence of the method is proved. An algorithm combined a gradient type method with a damped quasi-Newton method is applied to solve the discretized nonlinear equilibrium equations. Numerical experiments show that the Fourier-Chebyshev spectral method is efficient and capable of producing accurate numerical cavitation solutions. [ABSTRACT FROM AUTHOR]