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Critically ill patients are at high risk for hospital acquired infections, which can significantly increase the mortality rate and treatment costs for these patients. Therefore, in the process of treating the primary disease, strict prevention and control of new hospital infections is an essential component of the treatment for critically ill patients. The treatment of critically ill patients involves multiple steps and requires a concerted effort from various aspects such as theory, management, education, standards, and supervision to achieve effective prevention and control of hospital infections. However, there is currently a lack of unified understanding and standards for hospital infection prevention and control. To address this, in March 2024, a group of experts in critical care medicine, infectious diseases, and hospital infection from China discussed the current situation and issues of hospital infection control in the intensive care unit together. Based on a review of the latest evidence-based medical evidence from both domestic and international sources, 2024 Expert Consensus on Hospital Acquired Infection Control Principles in the Department of Critical Care Medicine was formed, aiming to provide a basis for the development of hospital infection prevention and control strategies in the field of critical care medicine.

Echovirus 11 (E11) has gained attention owing to its association with severe neonatal infections. From 2018 to 2023, a surge in severe neonatal cases and fatalities linked to a novel variant of genotype D5 was documented in China, France, and Italy. However, the prevention and control of E11 variants have been hampered by limited background data on the virus circulation and genetic variance. Therefore, the present study investigated the circulating dynamics of E11 and the genetic variation and molecular evolution of genotype D5 through the collection of strains from the national acute flaccid paralysis (AFP) and hand, foot, and mouth disease (HFMD) surveillance system in China during 2000–2022 and genetic sequences published in the GenBank database. The results of this study revealed a prevalent dynamic of E11 circulation, with D5 being the predominant genotype worldwide. Further phylogenetic analysis of genotype D5 indicated that it could be subdivided into three important geographic clusters (D5-CHN1: 2014–2019, D5-CHN2: 2016–2022, and D5-EUR: 2022–2023). Additionally, variant-specific (144) amino acid mutation sites and positive-selection pressure sites (132, 262) were identified in the VP1 region. Cluster-specific recombination patterns were also identified, with CVB5, E6, and CVB4 as the major recombinant viruses. These findings provide a preliminary landscape of E11 circulation worldwide and basic scientific data for further study of the pathogenicity of E11 variants.

Formation water scale blocks pipelines and results in oil/gas production decreasing and energy consumption increasing. Many methods have been developed to inhibit scale formation. However, these previous methods are limited by their complications and low efficiency. A new method is proposed in this paper that uses the scale in formation water as a nanomaterial to improve oil recovery via controlling particle size. A series of ligands were synthesized and characterized. Micrometer-CaCO3 was formed and accumulated to form scale of a large size under uncontrolled conditions. The tetradentate ligands (L4) exhibited an excellent capturing yield of Ca2+ (87%). The particle size was very small, but they accumulated to form large particles (approximately 1300 nm) in the presence of Na2CO3. The size of the CaCO3 could be further controlled by poly(aspartic acid) to form sizes of about 700 nm. The flooding test showed that this material effectively improved oil recovery from 55.2% without nano CaCO3 to 61.5% with nano CaCO3. This paves a new pathway for the utilization of Ca2+ in formation water.

Effectively enhancing oil recovery can be achieved by reducing the viscosity of crude oil. Therefore, this paper investigated the viscosity reduction behavior of carbon nanotube viscosity reducers with different molecular structures at the oil–water interface, aiming to guide the synthesis of efficient viscosity reducers based on molecular structure. This study selected carbon nanotubes with different functional groups (NH2-CNT, OH-CNT, and COOH-CNT) for research, and carbon nanotubes with varying carbon chain lengths were synthesized. These were then combined with Tween 80 to form a nanofluid. Scanning electron microscopy analysis revealed an increased dispersibility of carbon nanotubes after introducing carbon chains. Contact angle experiments demonstrated that -COOH exhibited the best hydrophilic effect. The experiments of zeta potential, conductivity, viscosity reduction, and interfacial tension showed that, under the same carbon chain length, the conductivity and viscosity reduction rate sequence for different functional groups was -NH2 < -OH < -COOH. The dispersing and stabilizing ability and interfacial tension reduction sequence for different functional groups was -COOH < -OH < -NH2. With increasing carbon chain length, conductivity and interfacial tension decreased, and the viscosity reduction rate and the dispersing and stabilizing ability increased. Molecular dynamics simulations revealed that, under the same carbon chain length, the diffusion coefficient sequence for different functional groups was -NH2 < -OH < -COOH. The diffusion coefficient gradually decreased as the carbon chain length increased, resulting in better adsorption at the oil–water interface. This study holds significant importance in guiding viscosity reduction in heavy oil to enhance oil recovery.

The long-term vibration of the carbon canister during vehicle operation can lead to changes in its performance, thereby affecting its performance on evaporation emissions. A vibration test bench simulating vehicle vibration characteristics is used to simulate the working state of the carbon canister under actual driving conditions, analyze the amount of carbon powder precipitation and flow resistance changes in the canister after long-term operation, and compare the adsorption and desorption performance of the canister before and after aging and their effect on the evaporative emissions. The results showed that the carbon canister will produce carbon powder precipitation after being continuously subjected to the forward and backward vibration of the vehicle. This leads to a decrease in the ultimate adsorption and desorption capacity of the aged carbon canister for fuel vapor, with a more significant decrease in adsorption capacity. However, in the 2-day Diurnal Breathing Loss(DBL) test, due to the increase in flow resistance of the aged carbon canister, it is more difficult for the adsorbed fuel vapor to diffuse outward. For the unsaturated carbon canister, fuel leakage and evaporative emissions can be reduced. In evaporative emission management, it is necessary to adjust the control strategy reasonably based on the working status of the carbon canister.

Prostate cancer (PCa) is the most common invasive malignancy for men in the USA. The incidence and mortality rates of PCa are significantly higher among African American men, as compared to those in Caucasian men. Betulinic acid (BA) is a penta-cyclic triterpenoid that is often found in the bark of several species of plants. It possesses a variety of biological activities, including anti-cancer activities. We examined the cytotoxic effects and endoplasmic reticulum (ER) stress induced by BA and its ionic derivatives with PCa cells derived from African Americans and Caucasian men. The viability of all PCa cells was reduced by the BA compounds, and the cytotoxicity of these BA compounds was independent of ethnicity and androgen dependency. The BA compounds induced modest effects on ER stress proteins when compared with ER stress inducers, tunicamycin and thapsigargin. The induction of glucose regulated protein 78 (GRP78) was largely correlated with the expression of C/EBP homologous protein (CHOP) and cleaved poly [ADP-ribose] polymerase (PARP)/caspase-3 in the PCa cells. In summary, our data demonstrated that BA compounds impaired the growth of PCa cells regardless of ethnicity – through GRP78- and CHOP-independent pathways.

The change of organ hemodynamics in critical patients is key to the impairment of organ function. Organ perfusion pressure is the direct power to ensure organ blood flow, which is affected by inlet organ pressure (arterial pressure) and outlet organ pressure (venous pressure). Different organs have unique perfusion pressure requirements and regulation systems for blood flow adjustment to match their physiological needs. As the supply side of organ perfusion, the blood flow of organs is influenced by mean arterial pressure (MAP)and autoregulation system. Organs with different autoregulatory abilities have different requirements for MAP, so the appropriate MAP should be decided according to the autoregulation range in clinical practice. However, organ blood flow perfusion is not only determined by the supply side, but also affected by venous reflux. Changes in arteriovenous gradient across important organs affect organ blood flow perfusion. Different organs have different tolerance levels for venous reflux disorders because their distance from the heart and the specificity of the organ itself. When conducting hemodynamic intervention, physicians should pay attention to the influence of different pressure changes on organ perfusion.

A carbon-chlorine co-doped mesoporous g-C3N4(C-Cl-CN) photocatalyst with a high specific surface area was prepared from melamine, glucose and ammonium chloride and its performance for photocatalytic degradation of rhodamine B(RhB) was investigated. The crystal structure, chemical composition and micro-morphology of the catalysts were characterized by X-ray diffraction pattern(XRD), X-ray photoelectron spectroscope(XPS), scanning electron microscope(SEM), UV-Vis diffuse reflection spectra(UV-Vis DRS) and photoluminescence(PL). The results show that C-Cl-CN has a high specific surface area(108.7 m2/g) and the rate constant of RhB degradation is 0.02290 min-1, which is 9.4 times higher than that of pure g-C3N4, and has excellent catalytic stability. Glucose and ammonium chloride act as double-bubble templates and elemental dopants in the polymerization process, which enhance the specific surface area of the catalyst on the one hand and reduce the energy bandgap, on the other hand, significantly enhance the light absorption performance of the catalyst.

The tubular dynamic hydrocyclone (TDH) holds great potential for the pre-deoiling of offshore oil platforms. However, the shear and turbulence in the flow field can cause the oil droplets, the dispersed phase in water, to break up when the swirling flow is produced by the swirler. A design method is proposed for the low-shear rotary swirler (LSRS) of TDH, the aim of which is to reduce the shear force and local turbulence during the fluid forming swirling flow. The blade setting angle of the LSRS is calculated based on the relative velocity vector between the fluid and the swirler. The distribution characteristics of the tangential velocity and turbulence in the TDH with LSRS are simulated by Computational Fluid Dynamics (CFD). The maximum stable droplet diameter is analyzed. The results show that the shear stress and turbulence energy dissipation rates are reduced by 74.6% and 68.5%, respectively, and that the stable droplet diameter is increased by more than 60%, compared to the conventional rotating swirler. In addition, a TDH prototype with LSRS was tested in an offshore oil field by continuous operation for more than 36 h. The average separation efficiency was 83%, and the average underflow oil concentration was 27 mg/L. The research also found that the drastic changes in the tangential velocity along the axial direction were critical to shear. Moreover, the results make up for the deficiency of the spatial variation of the tangential velocity in the dynamic cyclone separator.

Most of the satellites of the BeiDou navigation system work in geostationary orbit (GEO) and medium earth orbit (MEO), where the space plasma environment can make a severe impact on spacecraft. To measure the parameters of the plasma environment in GEO and MEO orbital space and to improve the design of the environmental adaptability of the satellites based on in situ probe data, a 2π-solid-angle omnidirectional field-of-view plasma detector was investigated and tested. The overall system design and detailed design of the structure and electric system were implemented. Then tests and verification were carried out to validate the reliability and capability of the detector. The detector can supply accurate in situ data of the plasma environment and be used to investigate the space plasma environment and its effects.

Sepsis is a major cause of death world wide. Evidence-based SSC guidelines promoted the global medical staffs' awareness of sepsis and septic shock, strengthened the understanding of the occurrence and development, and provided a common ground for all clinicians. SSC guidelines are the premise of implementing 'personalized'therapy, but management that strictly adheres to guidelines may not necessarily be the best option for each patient.Personalized management needs quantitative intervention according to the patient's pathophysiological characteristics and individual response. In this article, we will describe the correlation between 'personalized' therapy and guidelines through the recommendations of 2021 SSC guidelines, and expound on how to implement personalized therapy according to clinical guidelines.

Taking 7A52 aluminum alloy as the object, the preparation process optimization and corrosion resistance research of micro-arc oxidation ceramic layer were carried out.The response surface method was used to design the micro-arc oxidation test, and the effects of voltage, frequency, and graphene additive concentration on the thickness and porosity of the micro-arc oxidation ceramic layer were studied in the silicate electrolyte system.Furthermore, the Quadratic model was used to fit the data, the Criteria was used to conduct predictive analysis and perform experimental validation of predictive parameters and response values.The response surface analysis showed that when the conditions were 465.52 V of predicted voltage, 102.66 Hz of frequency and 0.38 g/L of graphene concentration, it possessed 9.992 61% of the optimal porosity and 15.427 7 μm of the optimal ceramic layer thickness.Experiments with the above conditions showed that the measured porosity of as-prepared layer was 9.6%, and the thickness was 12.76 μm.Moreover, the electrochemical tests on the micro-arc oxidation ceramic layer prepared under this conditions indicated that the corrosion potential increased significantly, and the corrosion current decreased, which inferred that the layer had good corrosion resistance.

Micro - arc oxidation technology of aluminum alloy is an environmental friendly and efficient surface treatment method of aluminum alloy in the 21st century. After years of theoretical accumulation and engineering practice, various kinds of additives were widely used in the industry to improve the performance of micro - arc oxidation coating. In this paper, the research status of various additives in micro - arc oxidation of aluminum alloy was introduced from three categories of soluble salt additive, nano particle additive and composite additive, their action mechanism was also discussed.

Bacillus Calmette – Guerin (BCG) is an immune regulator that can enhance hippocampal synaptic plasticity in rats; however, it is unclear whether it can improve synaptic function in a mouse model with Alzheimer’s disease (AD). We hypothesized that BCG plays a protective role in AD mice and investigated its effect on dendritic morphology. The results obtained show that BCG immunization significantly increases dendritic complexity, as indicated by the increased number of dendritic intersections and branch points, as well as the increase in the fractal dimension. Furthermore, the number of primary neurites and dendritic length also increased following BCG immunization, which increased the number of spines and promoted maturation. IFN-γ and IL-4 levels increased, while TNF-α levels decreased following BCG immunization; expression levels of p-JAK2, P-STAT3, SYN, and PSD-95 also increased. Therefore, this study demonstrates that BCG immunization in APP/PS1 mice mitigated hippocampal dendritic spine pathology, especially after the third round of immunization. This effect could possibly be attributed to; changes in dendritic arborization and spine morphology or increases in SYN and PSD-95 expression levels. It could also be related to mechanisms of BCG-induced increases in IFN-γ or IL-4/JAK2/STAT3 levels.

Recently, orbital angular momentum (OAM) has been adopted to measure the shape of static objects and the translation motion of moving objects in optical remote sensing. Most of these studies rely on measuring the intensity variation of OAM beams. However, the OAM intensity does not change with the rotation of the spinning object, but its phase changes. The phase variation is proved to be proportional to the object’s angular velocity. Since a rotating object will cause the OAM phase dependent on time, the OAM phase needs to be measured instantaneously, to support the OAM-based angular velocity measurement. In this work, we report a scheme to measure the angular velocity of a spinning object using a photonic OAM phase spectrum. A phase-to-intensity strategy is implemented to enable the real-time multi-OAM phase measurement, in which the phase can be determined with the intensities of four focal spots in a two-dimensional array generated by a phase-only spatial light modulator. The experimental results show that the average error of the measured angular velocity could be under 2.45% by detecting the phase of two OAM modes. This OAM-based angular velocity detection method provides a complementary approach to characterize the rotational Doppler effect, especially for slow angular motion.

The preformed particle gel (PPG) oil flooding system has several problems: (1) in the process of injection, particles easily settled and block the end face, which the process results in high pressure, and (2) the matching relationship between PPG particle size and formation pore throat has not been quantified sophisticatedly. To have a better description of the matching relationship between the median particle size of the dispersed phase and the pore throat diameter of the formation, its relationship has been quantified by us through the combination of core physical simulation and thin-tube experiments. Moreover, a calculation method of equivalent pore throat diameter has been proposed based on the principle of compact packing, which is more suitable for a sand-filled pipe model. To improve the performance of the system, the polymer and surfactant have been added into the PPG solution. The result indicates that when the pore throat diameter is between 1 to 5 times more than the median particle size of the dispersed phase, the dispersed phase can enter the pore throat smoothly, and the plugging rate is over 50%, which it means that the plugging is effective. When the pore throat diameter is more than 12 times of the median particle size of the dispersed phase, the plugging rate is less than 30%, and the effective residual resistance coefficient cannot be established. In order to improve the suspension performance of PPG particles, the polymer was added to the solution. In the presence of polymers, the suspension performance of PPG particles was greatly enhanced. Under the same injection volume, the PPG + polymer + surfactant system has the best oil displacement performance.

Supercritical multi-thermal fluid is an emerging and efficient heat carrier for thermal recovery of heavy oil, but the generation of supercritical multi-thermal fluid and its feasibility in thermal recovery are rarely discussed. In this paper, generation and flooding experiments of supercritical multi-thermal fluid were carried out, respectively, for the generation and feasibility of supercritical multi-thermal fluid. During the experiment, the temperature and pressure in the reactor and sand-pack were monitored and recorded, the fluid generated by the reaction was analyzed by chromatography, and enthalpy of the reaction product and displacement efficiency were calculated, respectively. The experimental results showed that the change in temperature and pressure in the reactor could be roughly divided into three stages in the generation process of supercritical multi-thermal fluid. The higher the proportion of oil in the reactant, the higher the maximum temperature in the reactor. When the proportion of oil and water in the reactant was constant, the temperature rise in the reactor was basically the same under different initial temperature and pressure conditions. Compared with the initial temperature and pressure, the oil–water ratio of the reactants had a significant effect on the generated supercritical multi-thermal fluid. The higher the proportion of oil, the more gas that was generated in the supercritical multi-thermal fluid, and the lower the specific enthalpy of the thermal fluid. Under the same proportion of oil and water, the gas–water mass ratio of the supercritical multi-thermal fluid generated by the reaction of crude oil was lower, and the specific enthalpy was higher. Through this study, it was found that supercritical multi-thermal fluid with a low gas–water mass ratio had higher oil displacement efficiency, higher early oil recovery rate, a larger supercritical area formed in the oil layer, and later channeling. The results of this study show that the optimal gas–water mass ratio of supercritical multi-thermal fluid was about 1, under which the oil displacement efficiency and supercritical area in the oil layer reached the maximum. Correspondingly, the optimal proportion of oil in the reactant when generating supercritical multi-component thermal fluid was about 10%. In oilfield applications, because the gas–water ratio in supercritical multi-component thermal fluid has a significant impact on oil displacement efficiency, the optimization of supercritical multi-thermal fluid should not only consider the generation process but also consider the oil displacement effect of the thermal fluid. The findings of this study could improve our understanding of the characteristics of generating supercritical multi-thermal fluid and the feasibility of supercritical multi-thermal fluid generated under different conditions in the oil displacement process. This research is of great significance for field applications of supercritical multi-thermal fluid.

Background: Optimal adjustment of cardiac preload is essential for improving left ventricle stroke volume (LVSV) and tissue perfusion. Changes in LVSV caused by central venous pressure (CVP) are the most important concerns in the treatment of critically ill patients.Objectives: This study aimed to clarify the changes in LVSV after negative fluid balance in patients with elevated CVP, and to elucidate the relationship between the parameters of right ventricle (RV) filling state and LVSV changes.Methods: This prospective cohort study included patients with high central venous pressure (CVP) (≥8 mmHg) within 24 h of ICU admission in the Critical Medicine Department of Peking Union Medical College Hospital. Patients were classified into two groups based on the LVSV changes after negative fluid balance. The cutoff value was 10%. The hemodynamic and echo parameters of the two groups were recorded at baseline and after negative fluid balance.Results: A total of 71 patients included in this study. Forty in VI Group (LVOT VTI increased ≥10%) and 31 in VNI Group (LVOT VTI increased 10.5 mmHg provided a sensitivity of 87.5% and a specificity of 77.4%. The AUC of CVP combined with the RVD/LVD ratio ≥0.6 was 0.926, which provided a sensitivity of 92.6% and a specificity of 80.4%.Conclusion: High CVP and RVD/LVD ratio ≥0.6 were significant associated with RV stressed in critically patients. Negative fluid balance will not always lead to a decrease, even an increase, in LVSV in these patients.

Usually satellite is under complex dynamic load during the launch phase,it’s easy to cause satellitestructure damageto influence spacecraftmission. Mechanical environment tests show that spacecraftstructure damage always occurs because of larger acceleration response of equipment such as large mass or high center of mass,and affecttedthe project development.Difference from the usual engineering solutions,a method based on gap elastic impactting is studiedto reducing damage. By constructing mechanical model,simulation and analysis has been done to a designated parameter structurepanel and equipment,results show that the methed as one of solutions of lower damage is valid to reducing defomation and load located at connection between equipment andstructure.

The high and low-temperature performance of five hydraulic bitumen binders was evaluated using the dynamic shear rheometer (DSR) test, infrared spectrum test and direct tensile (DT) test. These hydraulic bitumen binders were respectively applied for several pumped storage power stations (PSPS) projects that were constructed or under construction. In order to relate the bitumen performance to the mixture performance, the slope flow test, three-point bending test and thermal stress restrained specimen test were carried out on hydraulic asphalt mixtures. The test results indicated the DSR rheological master curves can well distinguish the difference of each bitumen binder as well as the effect of polymer modification. Phase angle master curves, black diagrams and infrared spectra all indicated that several penetration-grade hydraulic bitumen binders were not virgin bitumen binders but were modified with relatively lower SBS polymer content when compared with traditional SBS-modified bitumen. When selecting the commonly used Karamay SG70 hydraulic bitumen as a reference, the normal SBS-modified bitumen was superior to other bitumen in terms of low- and high-temperature performance. Several slightly SBS-modified bitumen binders did not always show consistent results, which indicated that slightly modified bitumen may not really have the desired performance as expected. Therefore, SBS-modified bitumen will be more promising when dealing with extremely low or high temperatures. Bitumen performance was well compared with the mixture performance by using the bitumen creep, relaxation and tensile failure strain corresponding to the asphalt concrete slope flow, the maximum bending strain and the failure temperature, respectively. Compared with the traditional penetration, softening point and ductility test, it indicated that the DSR rheological test, creep test, direct tensile test and stress relaxation test can be used as more powerful tools for the characterization and optimization of hydraulic bitumen binders.

Objective To understand the expression of miR⁃155 in the periodontal ligament cell population of pa⁃ tients with chronic periodontitis. Methods Periodontal ligament cells from the teeth of patients (n = 11) with chronic periodontitis were isolated and cultured, as were periodontal ligament cells from intact teeth obtained from healthy pa⁃ tients (n = 13) who had been treated with orthodontic extraction (the control group). The expression level of miR⁃155 in the two groups of periodontal ligament cell populations was detected by real⁃time fluorescence⁃based quantitative PCR. Results The periodontal ligament cell expression level of miR⁃155 was significantly higher in the chronic periodontitis group (0.93 ± 0.12) than in the control group (0.76 ± 0.25) (P < 0.01). Conclusion miR⁃155 expression in periodontal ligament cells was obviously stronger in patients with chronic periodontitis.

Based on adhesion models between rock surface groups and organic molecules, the interactions between the chemical groups on the rock surface and the components of crude oil and the interactions of the electrical double layers at the rock surface and oil-water interface were analyzed to investigate the abilities and microscopic mechanisms of wettability control by H+, OH− and inorganic salt ions in brine, and a new method of wettability control for reservoir rocks was built. The results show that the interaction forces between rock surface groups and oil molecules are van der Waals forces, Coulomb forces, hydrogen bonds, and surface forces. By changing these forces, the control mechanisms of surface wettability of reservoir rocks by brine are: transformation of chemical groups, change of interfacial potential, pH variation of injected water, multicomponent ionic exchange, and salting-in or salting-out effect. For sandstone reservoirs, with the decrease of concentration and valence state of positive ions in brine or the increase of pH (increasing pH has a negligible impact on the brine salinity), the interaction between rock surface and oil becomes weak, thus resulting in increase of water wettability of rock surface. For carbonate reservoirs, CaSO4 or MgSO4 brine with high concentration is beneficial to increase water wettability of rock surface. Therefore, it is feasible to control rock wettability and improve oil recovery by adjusting the ion components of injected water. Key words: rock surface, wettability, brine, intermolecular force, microscopic mechanism, enhanced oil recovery

Based on the physical optics method, the scattering characteristics of fractal rough surface coated objects are studied in the terahertz (THz) range herein. A blunt model based on fractal rough surfaces is built. The surface current is calculated according to the Fresnel reflection coefficient, and the Radar Cross Section (RCS) of the rough coated target is obtained. The RCS of rough and smooth surface targets are compared. Numerical results for a rough coated blunt cone model are provided, and discussed from the perspective of different frequencies and coating thickness values. The results show that the surface roughness of the target has a significant effect on scattering in the terahertz range.

Momentum wheel、CMG etc high speed rator-equipmentsareimportantnoiseoriginswhich haveabadinfluence on in-orbit satellite stability. As space resolution raisingandexposuretimeincreasing,disturbance influence become greater to image qulity,so reducing disturbance of high speed rotor is one of key design items for high-resolution optical remote sensing satellite on GEO robit. Currently multiple effective schemes have been presented to solve the problem by researchers,astrategy is discussed and proposed to reducing disturbance resulting from static unbalance base on rotor-equipment layout. With optimization and stimulation,theresults show that the method is valid to reducing disturbance from static unbalance by using layout optimization.

With the further aggravation of global warming and the increasingly serious problems of ecological environment, the construction of low-carbon cities has become an inevitable choice for the global response to climate change and the sustainable development of economy and society. In order to understand the basic situation of China’s low-carbon cities more specifically, this paper selects countries with different urbanization rates to carry out benchmarking analysis with China, hoping to draw on the experience of other countries from the national level through multi-dimensional comparison, and guide the direction of China’s future urban development. Firstly, this paper selects the basic indicators such as the total amount of carbon dioxide emissions, per capita carbon emissions and carbon emissions per unit GDP of each country; Secondly, it compares the proportion of coal in energy and other indicators, and analyzes the energy structure of each country in depth; Thirdly, it compares the trend of carbon emissions in each country among 1990-2017. Finally, in order to reflect the carbon emission in the development of urbanization, this paper uses the “urbanization carbon emission index”, which is the ratio of per capita carbon emission and urbanization rate, to show the relationship between the degree of urbanization and carbon emission. Through benchmarking analysis, we can more clearly understand the overall trend of low-carbon city construction in different countries, recognize the gap between China and other countries, and better guide the development of low-carbon cities in China in the future.

The bottom edge structure is a key factor affecting the flow pattern under the gate. The reasonable selection of bottom edge configuration plays an important role in the safe and stable operation of the gate. RNG k-ɛ model is used to simulate the gate water area. Through numerical simulation, the pressure cloud map and pressure data of monitoring points of water area under the gate are fully simulated. Influence of bottom edge structure on flow pattern. The results show that only the flat bottom gate always has negative pressure zone directly below the bottom edge, and the other three structures have no obvious negative pressure zone and move around the downward inclination Angle with time. According to the analysis of the characteristics of upper support and suction, it can be concluded that the upper support force increases with the increase of the front rake angle, and the upper support force of the flat-bottom gate is negative, showing the characteristics of suction.