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The dose equivalent rate of 225Ac and its daughter equilibrium system were measured and calculated. In addition, the dose equivalent rates of 131I and 99mTc with the same activity were also calculated. The tenth- and half-value thicknesses of lead for 225Ac were derived based on measurement data. The results show that dose equivalent rate at 0.5 m, for unshielded 85.5 MBq 225Ac, is 4.56 times higher than dose equivalent rate maximum limit 2.5 μSv/h of personnel operation positions form standard. The measured and theoretical values of dose equivalent rate at 0.5 m are more consistent than those at 0.15 m for 225Ac source, especially under lead shielding conditions of 0 mm, 5 mm, 10 mm, 15 mm, and 20 mm. For the same activity, measured dose equivalent rate of 225Ac is about half of 131I and about 1.5 times of 99mTc theoretical value. We should pay attention to external radiation protection during the use of 225Ac. It is suggested that, 20 mm can be used as the lead tenth value thickness, and 5 mm as the lead half value thickness conservatively for 225Ac and its descendants.

The increasing incidence of childhood obesity has emerged as a novel challenge in the realm of global public health. Studies have demonstrated that alterations in the composition of intestinal flora during the early stages of life contribute to the development of obesity by influencing nutrient absorption and metabolism, triggering inflammatory responses, and regulating the communication between the gut and brain. Currently, Bifidobacterium and Akkermansia muciniphila have been found to reduce body fat content, exhibit anti-inflammatory properties, and enhance intestinal barrier function, whereas Prevotella is strongly associated with improvements in individual glucose metabolism induced by dietary fiber. Translational application of specific intestinal flora benefits to body glycolipid metabolism is helpful for the early prevention and therapy of pediatric obesity. This review elucidates the impact of early-life changes in intestinal flora composition on childhood obesity explores the mechanisms by which intestinal flora contributes to obesity pathogenesis, and specifically focuses on recent advances in utilizing short-chain fatty acids for the regulation of intestinal flora and the amelioration of obesity, aiming to provide a theoretical foundation for the intervention of childhood obesity from the perspective of intestinal flora.

In response to the development requirements of small-sized gaseous tritium light sources, a wet coating and sintering process for preparing micron-sized ZnS(Cu) phosphors coatings on the inner wall of a slender glass tube was independently developed. And a coating device with controllable pressure, flow and temperature was designed and established. The coating device was used to explore the preparation process of fluorescent coatings for slender glass tubes with a specification of φ1.1 mm×550 mm, and to carry out research on the influence of slurry formulations on the viscosity of mixed liquid formulations and coating thickness. By optimizing the drying parameters, the coating was finally obtained in the slender glass tube. The cross-sectional SEM analysis shows that the coating has good compactness, and its thickness is (16.9±0.6) μm(n=32). The coating has good uniformity in thickness and is stable and does not fall off after being placed for a long time. The luminescence brightness of the tritium light tube sample obtained by this process is 0.642 cd/m2, with excellent uniformity. This provides a basis for device conditions and process optimization for the development of subsequent tritium light source products.

C22H26O6, orthorhombic, P212121 (no. 19), a = 7.6648(5) Å, b = 11.2663(6) Å, c = 22.7321(7) Å, V = 1963.0(2) Å3, Z = 4, Rgt (F) = 0.0652, wRref (F 2) = 0.1399, T = 273(2) K.

[Objective] Green ammonia, produced through carbon-free processes, has emerged as a high-quality carrier of hydrogen energy and stands as an alternative energy source vital for achieving carbon neutrality. Therefore, the planning and construction of green ammonia terminals hold crucial significance in facilitating the rapid development of the hydrogen energy industry chain and promoting the green transformation of the societal energy structure. [Methods] In this paper, a concise overview of ammonia's properties and advantages was provided that ammonia, as an efficient medium for energy and hydrogen storage, was able to reduce significantly the costs associated with hydrogen storage, transportation, and consumption, and enhance overall energy security due to its particular characteristics of high energy density, easy storage and transportation, zero carbon emissions at terminals, high safety and long-term storage. Various ammonia hydrogen projects and their trading details in different countries were investigated to analyze the global growth in green ammonia production capacity and demand, and to present a review of the current status of ammonia energy trade and terminal construction. In contrast to established technologies regarding LNG terminals, key processes and technologies involved in green ammonia terminals were elaborated on in this paper, including the technological system for green ammonia storage, liquid ammonia evaporator processing, and ammonia unloading and filling. [Results] This paper emphasized safety concerns associated with green ammonia terminals, specifically addressing the toxicity and potential for combustion-induced explosibility that may arise from liquid ammonia leakage. Additionally, it provided relevant preventive and protective measures. [Conclusion] The research and development of technologies for green ammonia terminals are of great significance for enhancing the utilization of green hydrogen energy in both the chemical fertilizer and energy sectors. The evolving demands of the new era call for a continued expansion of green ammonia terminals in terms of quantity and scale in the future. Furthermore, it is suggested that the renovation of bulk storage and transportation facilities, such as LNG terminals, can be an effective approach to cost reduction.

With the continuous promotion of energy revolution and energy transition, the product oil consumption in China will peak, and the trend of low delivery volume of product oil pipelines becomes evident increasingly, which puts enormous pressure on product oil pipeline companies. At the same time, as the “ammonia-hydrogen” green energy and “liquid sunshine” carbon neutralization technical routes are hotly promoted, and the related industries are developed vigorously, the production of liquid ammonia and methanol is bound to grow massively in the future. Therefore, a technical route for the large-scale batch transportation of liquid ammonia, methanol and other liquid new energy through the existing product oil pipeline systems was proposed, aiming to help the product oil pipeline companies create new growth poles.The batch transportation technology of liquid ammonia/methanol in product oil pipelines was systematically overviewed. Besides, five major technical challenges, including the hydraulic and thermal characteristics in batch transportation, prediction of mixed oil development,batch establishment and mixed oil cutting and treatment, applicability of pipeline materials and equipment, and leakage diffusion and safety protection, were elaborated. This could provide reasonable suggestions and reference directions for the field application of the batch transportation technology of liquid ammonia/methanol/product oil.

[Objective] Against the backdrop of the “dual carbon” initiative, ammonia has emerged as a carbon-free and hydrogen-rich energy carrier with exceptional growth potential. It offers advantages such as high volumetric energy density, and easy liquefaction and storage.However, complex environmental conditions for storage and transmission pose significant risks of corrosion to liquid ammonia tanks and pipelines. Therefore, it is essential to research liquid ammonia corrosion under complex transmission environments to ensure the construction and safe operation of “ammonia-hydrogen” energy infrastructure. [Methods] Through an investigation into the research progress related to liquid ammonia corrosion, this review explored the ammonia corrosion behavior and the mechanisms of stress corrosion cracking of different materials within various environments. Additionally, it provided a comprehensive overview of ammonia corrosion detection techniques and protection measures, along with insights into the future trends in ammonia corrosion research. [Results] This review highlights the following conclusions: The presence of oxygen, carbon oxides, sulfides, and chlorides accelerates ammonia corrosion, while water impurities exhibit a two-sided influence. Stress can potentially lead to stress corrosion cracking in liquid ammonia, with materials such as copper and its alloys being more susceptible, followed by high-strength steel and carbon steel. [Conclusion] To address the need for clarifying the mechanisms of liquid ammonia corrosion behavior and improving ammonia corrosion prevention measures in China, the following recommendations are put forth:(1) Conduct experiments and simulations to study the liquid ammonia corrosion behavior and internal corrosion mechanisms of different materials in the presence of multiple impurities.(2) Carry out critical failure boundary inspections and corrosion risk assessment in the context of pipeline steel and welding consumables with liquid ammonia,taking into consideration the actual transmission environments and material failure characteristics.(3) Establish a comprehensive corrosion control,protection,and evaluation standard system for liquid ammonia storage and transmission,encompassing various aspects such as design,material selection,manufacturing,and operation,and incorporating diverse corrosion prevention measures.

This paper first deconstructs the core of the college English precision education model, combines relevant theoretical knowledge, and constructs a college English precision education model based on artificial intelligence. Secondly, the convolutional neural network technology is integrated into the joint probability matrix decomposition model, and the resource recommendation list is generated through the cognitive ability level of students and their individualized needs so as to realize the precise, intelligent recommendation of English education resources. Finally, the performance of the recommendation for teaching English educational resources and the practical effect of the educational model are explored through comparative experiments. The results show that the precision rate and recall rate of the recommendation with a test set of 10% are 0.871 and 0.866, respectively, and the F1 value is 0.88. After the teaching practice, students’ listening ability improved by 0.132, expression ability improved by 0.13, reading ability improved by 0.132, writing ability improved by 0.130, and translation ability improved by 0.128. Based on the paper, the educational model has a positive impact on improving the level of English education in colleges and universities.

Developing efficient anodes for H2O2 production via water oxidation remains challenging. Here, the authors report a ZnGa2O4 anode with dual active sites to improve the selectivity and to resist the decomposition of H2O2, and the peak faradaic efficiency reaches 82% at a low potential.

ObjectiveTo provide the basis for dealing with similar incidents in the future， an outbreak of foodborne illness caused by the consumption of bread contaminated with Salmonella enteritidis was investigated.MethodsDescriptive epidemiological methods were used to analyze the clinical characteristics， epidemiological distribution and related risk factors of the cases. The etiological food was determined by retrospective cohort study. The biological samples， food remains and environmental samples of the cases and canteen employees were detected by laboratory testing. The causes of the outbreak were comprehensively analyzed based on the results of epidemiological investigation， laboratory tests and sanitary investigation.ResultsRetrospective cohort study showed that a batch of pre-packaged bread produced by a food factory in Chongqing on May 20， 2021 was the suspicious food. A total of 73 people ate the suspicious bread in this incident， and 55 of them got ill with a morbidity rate of 75.34% and a median incubation period of 15 h. At the same time， Salmonella enteritidis was detected in food remains， related environmental samples and anal swabs of patients.ConclusionThe incident was an outbreak of foodborne disease caused by bread contaminated with Salmonella enteritidis.

Rock masses in underground engineering are usually damaged, which are caused by rock genesis and environmental stress. Studying the constitutive relationship between rock strength and deformation under loading is crucial for the design and evaluation of such scenarios. The new damage constitutive model considering the dynamic change of joint damage was developed to describe the behavior of rocks under loading in this work. First, considering the influence of jointed rock mass structural features in their entirety, the Drucker–Prager criterion and the Hoek–Brown criterion were combined. Second, based on the idea of macro–micro coupling, the calculation formulae of damage variables were derived. Finally, the damage constitutive model of the jointed rock mass was established, and the proposed model was fitted and compared with the test data. Results show that the variation rules for damage value and peak strength are opposite, and the stress–strain is highly sensitive to changes in the parameter s of the model. Moreover, the proposed model can accurately describe the effect of joint deterioration on the entire process of rock mass compression failure, which shows that the damage constitutive models are useful for evaluating the strength characteristics of jointed rock mass in engineering practice.

C24H30O7, orthorhombic, P212121 (no. 19), a = 11.4194(5) Å, b = 13.4657(6) Å, c = 14.7549(7) Å, V = 2268.86(18) Å3, Z = 4, Rgt(F) = 0.0535, wRref(F2) = 0.1239, T = 273(2) K.

In order to improve the adaptability of hybrid A* algorithm to mining scene, this paper proposes a path optimization method for unmanned mine trucks. Firstly, applicability and curvature continuity of initial solution of hybrid A* algorithm are improved by curvature continuous Reeds-Shepp screening in combination with mining scenes, and then the segmented spline curve numerical optimization method based on quadratic programming is used to further smooth and interpolate the searched path. This method can be applied to the screening and smooth optimization of the initial solution of path planning, and provides a safe, smooth and drivable path for unmanned mine trucks that satisfies the kinematic constraints of the vehicle. The results of simulation comparison test and on site vehicle test show that the proposed method can significantly improve the applicability and smoothness of the search path by the traditional hybrid A* algorithm, and the optimization efficiency is better than the traditional discrete point optimization.

Exosomes are phospholipid bilayer vesicles secreted by living cells that can carry a variety of signaling molecules, such as RNA, DNA, protein, and lipids. Exosomes play a role in the transmission of signaling molecules between cells, thus regulating many physiological and pathological processes. The methods of extracting exosomes include differential centrifugation, density gradient centrifugation, exclusion chromatography, ultrafiltration, coprecipitation, polymer immune affinity, microfluidic separation technology, etc. Each of these extraction technologies has advantages and disadvantages; however, there is no unified international standard. In addition, the expression of specific proteins and genetic material of exosomes from different cell sources are different; thus, their expression characteristics and functions are also distinctive. Based on this situation, research on exosomes is limited to preclinical studies, and difficulties and challenges still exist in clinical application. This paper summarizes the progress of research in the field of exosomes, to understand the characteristics, modification and application of exosomes from different cell sources, and to summarize their advantages and disadvantages as well as challenges, which can help researchers better understand and master the performance of exosomes. Furthermore, improvement of standard procedures in the extraction and manufacturing of exosomes is important, as it will provide a reference for researchers to carry out exosome-related translational clinical research.

To ensure the national demand for gas supply and peak shaving, a project of capacity expansion is proposed for the Xiangguosi underground gas storage (UGS). A geologic integrity evaluation is urgently needed to optimize the upper operating pressure and ensure the long-term safe operation. Thus, based on the geological, seismic, well logging, and dynamic monitoring data as well as the indoor core experimental data, 3D static and 4D geomechanical models were established for this UGS. Some geomechanical characteristics of the geological body were analyzed. The stability of the caprock, base, and fault under different reservoir pressure was individually simulated and evaluated as well. The results show that, both the caprock of the Liangshan Formation and the base of the Hanjiadian Formation may produce a little formation deformation during the operation; the five reservoir-controlling faults have no risk of fault activation during the early UGS operation under current stress conditions, and their sealing performance is good; when the reservoir pressure is higher than the original formation pressure of 6 MPa, the integrity of the Xiangguosi UGS is at risk of instability. This research accurately and quantitatively evaluate the operation safety of the Xiangguosi UGS under the influence of dynamic stress field, which has important guiding significance for the optimization of its operation plan.

Objective:This study contributed to overcoming the disadvantages of hydrophobicity of CBD broad-spectrum oil and poor stability caused by oil coalescence. Methods: CBD broad-spectrum oil was dissolved in five kinds of solvents, and two kinds of solvents with better solubility were obtained by the appearance of the solution. The solubility of broad-spectrum oil in two solvents was determined by UV spectrophotometry at 313~363 K, and the solvent with the highest solubility was obtained. In this solvent, the solubility of CBD broad-spectrum oil was determined at 313~353 K to correlate the Apelblat model. The number of oil drops of CBD broad-spectrum oil with different concentrations and tween dispersant with different volume fractions were observed. Results: The two solvents with good solubility were caprylic capric triglyceride （CCT） and 1,2-propanediol. At the same temperature, the solvent with the highest solubility was CCT. Under CBD-CCT, the correlation coefficient （R2） of Apelblat model is more than 0.98, the relative deviation （RD） is less than 2.78%, and the root mean square error （RSMD） is 4.1×10-3. The relationship between molar solubility and temperature is in accordance with Apelblat model. When the mass concentration of CBD-CCT was 170 mg/mL, with and Tween 80 dispersant with 10% volume fraction added, the highest anti coalescence and stability of the system was found. Conclusion: CBD-CCT can be in a stable state and has positive significance in the preparation and storage of CBD food and health products.

Objective To investigate the effect of Objective Structured Clinical Examination (OSCE) in orientation training of night shift among newly recruited nurses. Methods Totally 26 registered nurses who required orientation training of night shift were divided into the observation group and control group. Routine theory and practice tests were carried out in the control group, and OSCE was performed in the observation group. The nurse’s satisfaction with training, comprehensive skills assessment outcome and exam result were observed and compared between two groups. Results The satisfaction rate of observation group was higher than that of control group (P＜0. 05). The scores of comprehensive skills assessment and theory test in the observation group were higher than those in the control group (P＜0. 05). Conclusion The OSCE in orientation training of night shift is potentially effective to enhance the comprehensive skills of nurses and improve their satisfaction. (目的 探讨客观结构化临床考试(OSCE)在新入科夜班护士准入培训中的应用效果。方法 26名注册护士分为观察组和对照组, 参加夜班准入培训。对照组护士采用常规理论及单项操作考试, 观察组采用OSCE。比较2组护士对培训的满意度、综合能力得分以及考试成绩。结果 观察组对培训效果的满意度高于对照组 (P＜0. 05)。观察组综合能力评分和考试成绩得分均高于对照组, 差异有统计学意义(P＜0. 05)。结论 OSCE应用于新入科夜班护士准入培训, 能有效提高其临床综合能力, 护士对该培训方式满意度较高。)

As one of the core hot components of aeroengines, the safe service of turbine blades is crucial to the operation of aeroengines.When the aeroengines encounter some emergency conditions, the turbine blades may suffer overheating, the temperature of which is much higher than the highest normal operating temperature. Overheating can lead to serious microstructural degradation and even premature failure of turbine blades. In this paper,the methods of overheat inspection and failure analysis were introduced, as well asthe effects of overheating on the microstructural degradation and mechanical propertiesof aeroenginesturbine blades. In addition, the damage assessment, life prediction and microstructure rejuvenation of superalloys after overheating were prospected in this paper, which provide a guidance and theoretical basis for the degradation evaluation and failure analysis of turbine blades as well as the development of new superalloys.

Cherenkov radiation in natural transparent materials is generally forward-propagating, owing to the positive group index of radiation modes. While negative-index metamaterials enable reversed Cherenkov radiation, the forward photon emission from a swift charged particle is prohibited. In this work, we theoretically investigate emission behaviours of a swift charged particle in the nanometallic layered structure. Our results show that Cherenkov photons are significantly enhanced by longitudinal plasmon modes resulting from the spatial nonlocality in metamaterials. More importantly, longitudinal Cherenkov photons can be directed either forward or backward, stringently depending on the particle velocity. The enhanced flexibility to route Cherenkov photons holds promise for many practical applications of Cherenkov radiation, such as novel free-electron radiation sources and new types of Cherenkov detectors.

We theoretically investigate the illusion device designed by a conformal transformation that can render an elliptic defect behave like a flat mirror. Different from illusion devices consisting of the complementary medium and anti-object with negative permittivity and permeability, our proposed illusion device requires only isotropic positive permittivity medium. It offers a possible route to eliminate the lateral shift in the conventional quasi-conformal carpet cloak. Interestingly, with the same conformal transformation, we can achieve an impedance-matched flat absorber by simply varying the shape and the refractive index of the defects. Both the illumination device and the absorber in our design have broad bandwidth, wide-illumination range and polarization-insensitive performance.

The unconsolidated sandstone in hydrothermal geothermal field in Jianghan basin is taken as the research object. The hydrostatic pressure is applied to a geostress equal to 12.5 MPa. After the deformation of sample is stabilised, the evolution and mechanism of the permeability of unconsolidated sandstone under the compaction of high hydrostatic pressure are studied, which can provide some suggestions for the selection of equipment operating parameters for the tailwater recharge process in the hydrothermal geothermal field. The results indicate that under high hydrostatic pressure compaction, the permeability of unconsolidated sandstone samples tends to be a constant valued of 4.0×103 m2 within the current range of 0.5 mL/min to 3.0 mL/min. The pressure difference between the two ends of the sample increases nonlinearly with time and the degree of nonlinearity gradually increases with the increase of flow rate, but eventually tends to be stabilised. In addition, the sample of unconsolidated sandstone forms a tubular erosion channel in the direction of penetration, extending to about 2/3 of the sample. Based on the stop time of particle transportation and the extension length of tubular erosion channel in the penetration direction, the average migration velocities of particles under different flow rates are determined. It is found that the particle migration velocity increases exponentially with the increase of flow rate, and the amount of microparticle migrated per unit time increases. When the pressure difference exceeds about 1/2 of the hydrostatic pressure, the sample presents erosion damage and upstream diameter shrinkage.

To build a vomit-free ward of scientific and standardized management mode, and to evaluate its clinical effects on preventing nausea and vomiting in patients undergoing chemotherapy.

Seawater electrolysis is a promising approach to produce hydrogen fuel and is also of great significance to seawater desalination. Here, the authors prepare 3D core-shell metal-nitride catalysts from earth-abundant elements for high-performance alkaline seawater electrolysis.

In order to investigate the relationship between rock microfracture mechanism and acoustic emission (AE) signal characteristic parameters under split loads, the MTS322 servo-controlled rock mechanical test system was employed to carry out the Brazilian split tests on granite, marble, sandstone, and limestone, while FEI Quanta-200 scanning electron microscope system was employed to carry out the analysis of fracture morphology. The results indicate that different scales of mineral particle, mineral composition, and discontinuity have influence on the fracture characteristics of rock, as well as the b-value. The peak frequency distribution of the AE signal has obvious zonal features, and these distinct peak frequencies of four types of rock fall mostly in ranges of 0–100 kHz, 100–300 kHz, and above 300 kHz. Due to the different rock properties and mineral compositions, the proportions of peak frequencies in these intervals are also different among the four rocks, which are also acting on the b-value. In addition, for granite, the peak frequencies of AE signals are mostly distributed above 300 kHz for granite, marble, and limestone, which mainly derive from the internal fracture of k-feldspar minerals; for marble, the AE signals with peak frequency are mostly distributed in over 300 kHz, which mainly derive from the internal fracture of dolomite minerals and calcite minerals; AE signals for sandstone are mostly distributed in the range of 0–100 kHz, which mainly derive from the internal fracture of quartz minerals; for limestone, the AE signals with peak frequency are mostly distributed in over 300 kHz, which mainly derive from the internal fracture of granular-calcite minerals. The relationship between acoustic emission signal frequency of rock fracture and the fracture scale is constructed through experiments, which is of great help for in-depth understanding of the scaling relationship of rock fracture.

Two bicrystal specimens containing high angle grain boundary (about 20 degrees) were prepared by seed crystal method. The effect of Hf on the as-cast, heat-treated grain boundary microstructure, composition and stress rupture properties under 1100℃/100MPa was investigated in Ni-based single crystal superalloy contained Re with different contents of Hf (mass fraction:0%, 0.4%). The results show that Hf addition results in the increase of the volume fraction of (γ+γ') eutectic and MC along the grain boundary. The volume fraction of cellular recrystallization microstructure is significantly decreased after heat treatment with Hf addition. The transverse stress rupture life is observed to increase significantly under 1100℃/100MPa in the Hf-containing alloy. The stress rupture properties are closely related to the type, morphology, content and composition of the precipitation phase along grain boundary, but the obvious segregation of Hf is not observed. This study can be helpful for the understanding of Hf's role of strengthening mechanism in grain boundary in advanced Ni-based single crystal superalloy.

Photoelectric non-contact measurement methods have been widely implemented in space target location, micro-displacement measurement and space optical communication. In term of the reliability and precision of measurement systems, it is a great significance to obtain the laser center location accurately. Since the two-dimensional position sensitive detector (2-D PSD) can continuously detects the gravity center position of the laser spot on its photosensitive surface, this paper provides a flexible method with high precision for the nonlinear correction of PSD as well as a new idea for PSD-based moving laser center positioning. Above all, a laser device system that rotating around a fixed-axis is designed, and the rotation angle can be controlled with the rotation accuracy of 0.5°. The trace of the gravity center of the rotating spot generated by the device on the PSD surface is detected, and then the laser center location is obtained after further processing of data. In order to improve the detection accuracy of PSD, this research mainly focuses on the nonlinear correction method of the detector and the fitting method of the gravity center trace of the laser spot. Moreover, the effects of different sizes of light spots projected onto the 2-D PSD on the collected photocurrent and estimated coordinates were analyzed by experiments. From the experimental results, the non-linear error of PSD is corrected by the error curved surface interpolation method, the overall error is reduced by more than 32%, and the linearity of the positioning of the laser moving along the diagonal of PSD is 0.2%.

Median filtering (MF), a non-linear smoothing operation, has often been utilized as a means of image denoising to protect image edges and hide the traces of image tampering. Although the existing MF forensics methods have achieved excellent performance without post-processing, there is still a challenge of detecting MF in small image size and JPEG compression scenario. To meet this challenge, a robust MF forensic method using convolutional-neural-network (CNN)-based multiple residuals learning is proposed in this paper. Firstly, to reveal the traces left by MF, we use multiple high-pass filters to initialize the weights of the pre-processing layer, and obtain discriminative residuals to characterize MF artifacts in various aspects. Then the output of the pre-processing layer is employed as the input of CNN, which is elaborately designed to extract rich hierarchical features for further classification. Furthermore, Batch Normalization (BN) is introduced as a regularization method to help accelerate convergence of the entire network. The extensive experimental results on the composite database demonstrate that the proposed method is superior to the state-of-the-art methods when detecting MF in both JPEG compressed and small size images.