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The Sanshui salt mine is the sole location in the Guangdong province of South China with the potential to construct a salt cavern gas storage (SCGS) facility. Nevertheless, the gas storage construction of this mine faces significant challenges due to the presence of low‒grade salt deposits and numerous interlayers. To demonstrate the feasibility and calculate the gas storage capacity in this specific mining area, two representative salt caverns within this salt mine were simulated using a self-developed cavern-building simulation program, enabling us to accurately determine their respective volumes and shapes. Herein, the findings indicate that the combined caverns possess a total mining space volume of 1,157,000 m3, with the brine space accounting for merely 291,800 m3 (representing 25.22% of the overall mining space), and an extensive sedimentary volume of 865,200 m3 is also observed (constituting approximately 74.78% of the total mining capacity). Fortunately, this study has revealed that the sediments exhibit a porosity exceeding 40% and possess favorable permeability; consequently, countermeasures have been proposed to enhance the gas storage capacity within the pore space of these caverns, and we also utilized FLAC3D software for numerical simulation calculations to compare the stability of the cavern under different conditions of sediment pore utilization by calculating the volume loss rate, cavern wall displacement deformation, and plastic zone distribution. Moreover, the proposed method is anticipated to double the caverns’ working gas volume, increasing it from 40 million m3 to nearly 80 million m3. On the other hand, the long-term stability of caverns is numerically assessed under different pore space utilization rates of the sediments. The results also indicate that the caverns’ volume shrinkage, plastic zones, and surrounding rock displacement remain within allowable limits during 30 years of gas storage operation. The primary problem in the subsequent phase lies in effectively achieving gas injection and brine removal from the pore space of sediments while devising a methodology to extend this method to other salt caverns within similar salt mine areas. Thus, this study provides theoretical and technical guidance for the establishment of gas storage in existing salt caverns in the Sanshui salt mine and in salt mines worldwide that share similar geological conditions.

Background: Studies have shown that vagus nerve-mediated inflammatory reflex could inhibit cytokine production and inflammation in sepsis animals. Objectives: This study aimed to explore the efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) on inflammation and disease severity of sepsis patients. Methods: A randomized, double-blind, sham-controlled pilot study was performed. Twenty sepsis patients were randomly assigned to receive taVNS or sham stimulation for five consecutive days. Stimulation effect was assessed with serum cytokine levels, Acute Physiology and Chronic Health Evaluation (APACHE) Ⅱ score, and Sequential Organ Failure Assessment (SOFA) score at baseline and on Day 3, Day 5, and Day 7. Results: TaVNS was well tolerated in the study population. Patients receiving taVNS experienced significant reductions in serum TNF-α and IL-1β levels and increases in IL-4 and IL-10 levels. SOFA scores decreased on Day 5 and Day 7 compared with baseline in the taVNS group. However, no changes were found in sham stimulation group. The changes of cytokine from Day 7 to Day 1 were greater with taVNS than sham stimulation. No differences in the APACHE Ⅱ score and SOFA score were observed between the two groups. Conclusions: TaVNS resulted in significantly lower serum pro-inflammatory cytokines and higher serum anti-inflammatory cytokines in sepsis patients.

Seal components made of flexible graphite have excellent resistance to temperature, while sealing of high pressure fluids is unsatisfactory. The sealing behavior of flexible graphite rings is characterized by the ratio of the contact pressure to the axial pressure. The FEA results show that the lateral pressure decreases roughly linearly along the direction of the sealing path, and the lateral pressure coefficient increases with increasing axial pressure. We design a combined seal structure based on flexible graphite rings, and extract the contact pressure along two sealing paths. The results imply that the self-sealing effect is more favorable when the pressure of the sealing fluid is increased. The effect of the friction coefficient on the contact pressure is not significant, except at the beginning of the sealing path. Sealing effects are tested under the coupling condition of 350°C and 50 MPa, which verify the sealing performance under high temperature and high pressure. The comparison of the test results of “ kf ” (the product of lateral pressure coefficient and friction coefficient) with those of the FEA validates the rationality of the analytical approach. The comprehensive coefficient “ kf ” can be easily obtained by testing, and can be used as a key parameter for seal design.

Summary: Background: Immune-enhancing thymosin alpha 1 (Tα1) therapy may reduce infected pancreatic necrosis (IPN) in acute necrotising pancreatitis (ANP). However, the efficacy might be impacted by lymphocyte count due to the pharmacological action of Tα1. In this post-hoc analysis, we tested the hypothesis that pre-treatment absolute lymphocyte count (ALC) determines whether patients with ANP benefit from Tα1 therapy. Methods: A post-hoc analysis of data from a multicentre, double-blind, randomised, placebo-controlled trial testing the efficacy of Tα1 therapy in patients with predicted severe ANP was performed. Patients from 16 hospitals of China were randomised to receive a subcutaneous injection of Tα1 1.6 mg every 12 h for the frst 7 days and 1.6 mg once a day for the following 7 days or a matching placebo during the same period. Patients who discontinued the Tα1 regimen prematurely were excluded. Three subgroup analyses were conducted using the baseline ALC (at randomisation), and the group allocation was maintained as intention-to-treat. The primary outcome was the incidence of IPN 90 days after randomisation. The fitted logistic regression model was applied to identify the range of baseline ALC where Tα1 therapy could exert a maximum effect. The original trial is registered with ClinicalTrials.gov, NCT02473406. Findings: Between March 18, 2017, and December 10, 2020, a total of 508 patients were randomised in the original trial, and 502 were involved in this analysis, with 248 in the Tα1 group and 254 in the placebo group. Across the three subgroups, there was a uniform trend toward more significant treatment effects in patients with higher baseline ALC. Within the subgroup of patients with baseline ALC≥0.8 × 10ˆ9/L (n = 290), the Tα1 therapy significantly reduced the risk of IPN (covariate adjusted risk difference, −0.12; 95% CI, −0.21,-0.02; p = 0.015). Patients with baseline ALC between 0.79 and 2.00 × 10ˆ9/L benefited most from the Tα1 therapy in reducing IPN (n = 263). Interpretation: This post-hoc analysis found that the efficacy of immune-enhancing Tα1 therapy on the incidence of IPN may be associated with pretreatment lymphocyte count in patients with acute necrotising pancreatitis. Funding: National Natural Science Foundation of China.

Erosion in multiphase flow is very common to the industrial piping systems and it will increase the safety risk of the piping systems. Once accidents occur, it will bring about serious economic loss and environment pollution.By investigating the research on the erosion of multiphase pipelines, the progress of research at home and abroad was presented in terms of the theoretical model, the erosion test, the numerical simulation and the microscopic mechanism. Meanwhile, the existing problems in current research on erosion of multiphase pipelines were pointed out and discussed, and the development direction in future was also clarified. In general, the research results could provide reference for the deep understanding and mastering of the erosion mechanism of multiphase pipelines, as well as the safe and efficient development and transportation of oil and gas resources.

The crystallization behavior of wax molecules is the root cause of wax deposition. In this study, molecular dynamics simulations were used to investigate the aggregational crystallization behavior of wax molecules in a crude oil system. The results show that wax molecules produce ordered wax crystal structures from the disordered liquid phase crude oil system under van der Waals forces at low temperatures. The crystallization of wax molecules consists of three main processes: carbon chain extension, nucleation of wax molecules and wax crystal growth. The lower the temperature of the crude oil system and the lower the cooling rate, the higher the degree of aggregation of wax molecules, the smaller the number of wax crystals and the larger the crystal size. In addition, asphaltene molecules are found to aggregate by face-to-face stacking and T-shaped stacking at low temperatures. Based on the spatial steric hindrance effect, the asphaltene aggregates prevent further aggregation between wax crystal clusters. Asphaltenes lead to an increase in the liquid content of the wax deposit layer, causing the yield stress of the deposit to decrease and the structural strength to weaken.

The economic performance of single pedal matched regenerative braking system for pure electric vehicle under CLTC condition is studied. Firstly， the differences between the two working conditions of CLTC and NEDC are compared， and a virtual simulation model is built on AVL_CURISE platform based on a certain vehicle， a pure electric vehicle model equipped with a single pedal braking energy recovery control system is established. The economic performance differences between the single pedal system and the original parallel braking regenerative system are compared under different working conditions. The simulation results show that， the single pedal braking system is better than the former parallel braking system， the replacement of NEDC with CLTC have limited impact on driving range.

The spin–orbit coupling (SOC) effect is the dominant origin of the topological properties in a topological insulator which can be induced and enhanced through various methods. Here we theoretically study the effects of varying SOC on the topological properties of two-dimensional kagome lattice based on the tight-binding approximation. We find that the system can undergo a transition between two non-trivial topological states by tuning the SOC strength. In addition, the topological phase transition can be achieved with a weaker SOC under a uniform tensile strain, which suggests that strain engineering can be used to regulate topological states. Besides, the characteristics of optical spin Hall conductivity are also studied, which supplies an experimental determination to reveal the different topological states. Furthermore, we propose an external mechanical strain modulated spin-switch device, which can generate opposite spin currents under stretch and compressed strain. Our results indicate that with the combination of SOC and strain, kagome lattice materials have potential applications on tunable spintronics and optoelectronic devices.

This study combined theoretical analysis, physical simulation, and numerical simulation to discuss the influences of the structural evolution and motion characteristics of a hard roof during thickening coal seam mining on working face pressure. Results showed that during the mining of the thickening coal seam with a hard roof, the settlement curve of low-level strata was a stepwise wave slope, and the settlement curve of high-level strata shifted from a “V-shaped” distribution pattern to a parabola under the full mining of the coal seam. When the mining thickness was relatively small, the mining space expanded with the increase in mining thickness due to the “masonry beam” structure formed by the low-level, sub-critical overlying strata. The low-level critical strata formed a “composite cantilever beam” structure with a hard immediate roof after advancing into the caving zone. After complete recovery, the overlying strata were in a steady-movement state, and the plastic failure zone of the overlying strata of the thickening coal seam presented obvious distribution characteristics of longitudinal and transverse partitions. This study provides theoretical reference for coal seam mining under similar geological conditions.

Splines are irreplaceable in high-speed aviation fields due to their simplicity, reliability, and high specific power. Aviation splines are not only subjected to severe operating mechanical loads, but also sometimes operate under grease-lubricated and non-lubricated environments. All of this results in aviation splines suffering widespread failures. Since the 1960s, many researchers have carried out much research on aviation splines. The wide range of research topics demonstrates the technical challenges of understanding aviation spline. This paper reviews the research of aviation spline from the aspects of failure form, fatigue strength, surface contact stress, effects of lubrication, and misalignment on wear, as well as experiments. Relevant research shows crowned splines can mitigate the spline wear process induced by angular misalignment, and oil-lubricating splines experience almost no wear. This paper also looks forward to the future development directions of aviation splines.

The main purpose of this study was to investigate the flexural behavior of high-ductility fiber-reinforced concrete (HDC) and propose a suitable method for evaluating flexural toughness. The flexural strength, deformation, and toughness of HDC were investigated through four-point bending tests with specimens of 40 × 40 × 160 mm. The test parameters were fiber volume fractions (0%, 1%, 1.5%, and 2%), water–binder ratios (0.24, 0.26, 0.29, and 0.32), and ages (28 d and 56 d). The experimental results showed that polyvinyl alcohol (PVA) fibers led to significant improvement in the flexural behavior of HDC due to its strain-hardening behavior and excellent crack dispersion capacity. The ultimate flexural strength of HDC with 2% PVA fibers of about 15.32 MPa showed an increase of up to 221%. The deformation and flexural toughness ratios were 23 times and 1.43 times higher, respectively, than the specimens without fibers. A simple and practical method for evaluating the flexural toughness of HDC was proposed, which solved many problems with the existing methods. This method made full use of the peak load, which overcame the difficulty of identifying the initial crack information, solved the insufficient deflection limit, and provided a more comprehensive and accurate evaluation by selecting characteristic points evenly distributed throughout the loading process.

A wideband 220 GHz subharmonic mixer based on monolithic integration technology is proposed in this paper. It features 12 Mm-thick GaAs membrane with anti-parallel Schottky diodes working at THz band monolithically integrated on the membrane. The optimization principles of low-parastics Schottky diodes and the fabrication process of GaAs MMIC membrane diodes are elaborated. To realize optimum performances of the mixer, the dimensions of the integrated diodes and the matching network are optimized with harmonic balance simulation and load-pull techniques. An IF low pass filter with compact microstrip resonance cell (CMRC) configuration and an improved perpendicular coax-to-microstrip connection are used to realize wide IF band. The measured results show that the single sideband (SSB) conversion loss of this mixer is less than 10.5 dB from 185 to 255 GHz with fixed IF of 1 GHz, while the double sideband (DSB) noise temperature is better than 1400 K in this frequency range. Using fixed local oscillator (LO) frequency of 110 GHz, the measured SSB conversion loss is 7.4-10.7 dB within 185-255 GHz, indicating the good performances of the mixer with IF from DC to 35 GHz. The GaAs monolithic integration technology provides an approach for massive manufacturing of identical circuits and the proposed mixer with wideband characteristics will be applied in 220 GHz imaging systems in the near future.

In this paper, the development of two high power 220 GHz frequency triplers is proposed. The GaAs Schottky diodes with six nodes are applied to realize high efficiency 220 GHz tripler, while the application of GaN Schottky diodes with eight nodes is another attempt to improve power handling of the 220 GHz tripler. To reduce thermal effect of high power multipliers, the AlN substrates with high thermal conductivity are applied to provide better heat dissipation at the diode areas. A combination of electrical and thermal model of the Schottky diodes is established while the optimization of 220 GHz triplers are realized with 3D electromagnetic (EM) simulation and harmonic balanced simulation. Good agreement is achieved between the simulated results based on electro-thermal model and measured performances of the triplers. At room temperature, peak efficiency of the tripler based on GaAs Schottky diodes is 17.8%, while the maximum output of the tripler is 38.2 mW with 300 mW input power. As for the 220 GHz GaN Schottky diode tripler, measured results show that the maximum power handling is beyond 400 mW. The peak efficiency and maximum output are 4.7% and 18.4 mW, respectively. The proposed methods of developing high power multipliers can be applied in higher frequency band in the future.

It is known that chronic stress modulates multiple processes in a complex microenvironment, such as angiogenesis and immune function. However, the role of chronic stress inducing tumor angiogenesis and how it contributes to tumor progression are not quite clear. The following study assess psychological state from numerous ambulatory cancer cases (n=332), and chronic stress-related hormone levels were further measured. Here, we show that chronic stress not only causes behavioral changes in human, most importantly attributed to an elevated level of stress-related hormones. To address this, isoprenaline, the agonist of β2-adrenergic receptor (β2-AR), was utilized for simulating chronic stress and demonstrating the mechanism of stress in tumor angiogenesis at molecular level both in vivo and in vitro. As suggested by this study, isoprenaline promote VEGF autocrine of HUVECs, which can induce plexinA1 and VEGFR2 expression. Moreover, we show that isoprenaline promoted the expression of p-JAK2 and p-STAT3 in vitro. The results reveal that, isoprenaline enhances the autocrine of VEGF in HUVECs and up-regulating plexinA1 and VEGFR2 levels, thus activating the phosphorylation of JAK2-STAT3 pathway, the two essential parts during angiogenesis. The present work indicates that, the mechanism of chronic stress in enhancing angiogenesis is probably achieved through activating the plexinA1/VEGFR2-JAK2-STAT3 signal transduction pathway within HUVECs, and this is probably a candidate target for developing a strategy against angiogenesis in cancer.

Introduction Infected pancreatic necrosis (IPN) and its related septic complications are the major causes of death in patients with acute necrotising pancreatitis (ANP). Therefore, the prevention of IPN is of great clinical value, and immunomodulatory therapy with thymosin alpha 1 may be beneficial. This study was designed to test the hypothesis that the administration of thymosin alpha 1 during the acute phase of ANP will result in a reduced incidence of IPN.Methods and analysis This is a randomised, multicentre, double-blind, placebo-controlled study. 520 eligible patients with ANP will be randomised in a 1:1 ratio to receive either the thymosin alpha 1 or the placebo using the same mode of administration. The primary endpoint is the incidence of IPN during the index admission. Most of the secondary endpoints will be registered within the index admission including in-hospital mortality, the incidence of new-onset organ failure and new-onset persistent organ failure (respiration, cardiovascular and renal), receipt of new organ support therapy, requirement for drainage or necrosectomy, bleeding requiring intervention, human leucocyte antigens-DR(HLA-DR) on day 0, day 7, day 14, and so on and adverse events. Considering the possibility of readmission, an additional follow-up will be arranged 90 days after enrolment, and IPN and death at day 90 will also be served as secondary outcomes.Ethics and dissemination This study was approved by the ethics committee of Jinling Hospital, Nanjing University (Number 2015NZKY-004-02). The thymosin alpha 1 in the prevention of infected pancreatic necrosis following acute necrotising pancreatitis(TRACE) trial was designed to test the effect of a new therapy focusing on the immune system in preventing secondary infection following ANP. The results of this trial will be disseminated in peer-reviewed journals and at scientific conferences.Trial registration number ClinicalTrials.gov Registry (NCT02473406).

Gravity displacement often occurs when drilling a vertical fractured formation, causing a downhole complexity with risk of blowout and reservoir damage, well control difficulty, drilling cycle prolongation, and increased costs. Based on an experimental device created for simulating the gravity displacement, various factors affecting the displacement quantity were quantitatively evaluated by simulating the fracture width, asphalt viscosity, drilling fluid density, and viscosity under different working conditions, and a liquid–liquid displacement law was obtained. Using the theories of rock mechanics, fluid mechanics, and seepage mechanics, based on conformal mapping, as well as a fracture-pore double substrate fluid flow model, we established a steady-state mathematical model of fractured formation liquid–liquid gravity displacement by optimizing the shape factors and using a combination of gravity displacement experiments to verify the feasibility of the mathematical model. We analyzed the influence of drilling fluid density, fracture height and length, and asphalt viscosity on displacement rate, and obtained the corresponding laws. The results show that when the oil–fluid interface is stable, the fracture width is the most important factor affecting the gravity displacement, and plugging is the most effective means of managing gravity displacement.

The active distribution network (ADN) represents the future development of distribution networks, whether the islanding phenomenon occurs or not determines the control strategy adopted by the ADN. The best wavelet packet has a better time-frequency characteristic than traditional wavelet analysis in the different signal processing, because it can extract better and more information from the signal effectively. Based on wavelet packet energy and the neural network, the islanding phenomenon of the ADN can be detected. Firstly, the wavelet packet is used to decompose current and voltage signals of the public coupling point between the distributed photovoltaic (PV) system and power grid, and calculate the energy value of each decomposed frequency band. Secondly, the network is trained using the constructed energy characteristic matrix as a neural network learning sample. At last, in order to achieve the function of identification for islanding detection, lots of samples are trained in the neural network. Based on the actual circumstance of PV operation in the ADN, the MATLAB/SIMULINK simulation model of the ADN is established. After the simulation, there are good output results, which show that the method has the characteristics of high identification accuracy and strong generalization ability.

Abstract Background The role of stress signals in regulating gastric cancer initiation and progression is not quite clear. It is known that stress signals modulate multiple processes such as immune function, cell migration and angiogenesis. However, few studies have investigated the mechanisms of how stress signals contribute to gastric cancer angiogenesis. Methods Here, we used β2-adrenergic receptor (β2-AR) agonist isoprenaline to imitate a stress signal and demonstrated the molecular mechanism underlying stress’s influence on tumor angiogenesis. Results We found that isoprenaline stimulated vascular endothelial growth factor (VEGF) secretion in gastric cancer cells and plexin-A1 expression was induced by human recombinant VEGF165 in both gastric cancer cells and vascular endothelial cells. Furthermore, interfere with plexin-A1 expression in gastric cancer cells influence HUVEC tube formation, migration and tumor growth in vivo. Conclusions These findings suggest that isoprenaline stimulate VGEF secretion and subsequently up-regulate the expression of plexin-A1 and VEGFR2 in gastric cancer cells, which form a positive impetus to promote tumor angiogenesis. This study reveals a novel molecular mechanism that a stress signal like isoprenaline may enhance angiogenesis via activating plexin-A1/VEGFR2 signaling pathway in gastric cancer, which may be a potential target in development of an anti-angiogenic therapy for gastric cancer.

Background. Both long-term proton pump inhibitor use and surgical fundoplication have potential drawbacks as treatments for chronic gastroesophageal reflux disease (GERD). Our aim was to investigate the potential efficacy of antireflux mucosectomy (ARMS) in porcine and determine the optimal circumference of resection in relation to gastroesophageal junction (GEJ). Methods. Nine pigs were allocated into the following 3 groups by computerized randomization: group A: control, group B: 1/3 circumference of the esophagus, and group C: 2/3 circumference of the esophagus. We performed mucosectomy with a crescentic mucosal resection at 3 cm above the GEJ and 1 cm below the GEJ. The animals were kept on a liquid diet for 24 h prior to endoscopy. At 6 weeks, animals underwent esophagoscopy, barium radiography, gastric yield pressure (GYP), and gastric yield volume (GYV) determination. Results. The weight of swines has no significant difference, and all pigs had maintained their weight after the procedure. We both found scar formation at the GEJ in group B and C. Compared with group A and B, group C produced significantly higher GYP (24.23±3.42 mmHg, p=0.004) and significantly smaller GYV (2200.0±238.96 mL, p=0.028) after 6 weeks. Barium radiography showed that the width of the cardia was narrower (13.73±1.19 mm, p=0.032) in group C after 6-week postprocedure. Conclusion. Our study demonstrated the potential antireflux effect of ARMS. We also recommend the 2/3 circumference resection of mucosa at 3 cm distance from the GEJ.

Frequency multipliers and mixers based on Schottky barrier diodes (SBDs) are widely used in terahertz (THz) imaging applications. However, they still face obstacles, such as poor performance consistency caused by discrete flip-chip diodes, as well as low efficiency and large receiving noise temperature. It is very hard to meet the requirement of multiple channels in THz imaging array. In order to solve this problem, 12-μm-thick gallium arsenide (GaAs) monolithic integrated technology was adopted. In the process, the diode chip shared the same GaAs substrate with the transmission line, and the diode’s pads were seamlessly connected to the transmission line without using silver glue. A three-dimensional (3D) electromagnetic (EM) model of the diode chip was established in Ansys High Frequency Structure Simulator (HFSS) to accurately characterize the parasitic parameters. Based on the model, by quantitatively analyzing the influence of the surface channel width and the diode anode junction area on the best efficiency, the final parameters and dimensions of the diode were further optimized and determined. Finally, three 0.34 THz triplers and subharmonic mixers (SHMs) were manufactured, assembled, and measured for demonstration, all of which comprised a waveguide housing, a GaAs circuit integrated with diodes, and other external connectors. Experimental results show that all the triplers and SHMs had great performance consistency. Typically, when the input power was 100 mW, the output power of the THz tripler was greater than 1 mW in the frequency range of 324 GHz to 352 GHz, and a peak efficiency of 6.8% was achieved at 338 GHz. The THz SHM exhibited quite a low double sideband (DSB) noise temperature of 900~1500 K and a DSB conversion loss of 6.9~9 dB over the frequency range of 325~352 GHz. It is indicated that the GaAs monolithic integrated process, diodes modeling, and circuits simulation method in this paper provide an effective way to design THz frequency multiplier and mixer circuits.

Single crystal of Sm0.5Tb0.5FeO3 was grown by an optical floating zone method. The spin reorientation transition behavior (Γ2 → Γ24 → Γ4) is observed in the temperature range from 150 to 250 K. The dynamics of spin reorientation transition is studied by terahertz time-domain spectroscopy (THz-TDS). FM mode was only discovered when temperature is below 55 K. And the FM mode resonant frequency increases from 0.216 THz to 0.268 THz with temperature deceasing from 55 K to 39 K. The AFM mode resonant frequency is fixed at 0.542 THz except in the very low temperature range. Our results demonstrate that THz-TDS is an effective means to study the dynamical iron ions SRT in RFeO3.