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The motor rotating shaft of an aircraft centrifugal fuel pump is prone to mechanical damage after long-time friction with the dynamic seal， which would cause fuel to leak from the fuel pump nozzle and affect flight safety.In order to address the wear of the rotating shaft， an additive repair technology that involved spraying a WC carbide coating on its surface using HVOF was adopted.Three WC-12Co carbide coatings，each with different microstructures and mechanical properties， were prepared on the surface of 2Cr13 substrate by adjusting the kerosene flows in the HVOF process.The effect of kerosene flow on the porosity， microhardness， fracture toughness， adhesive strength and wear properties of the coatings was investigated.Results showed that with the oxygen flow kept constant，an increase in the kerosene flow rate led to increased particle temperature and velocity， reduced porosity of the coating， and enhanced fracture toughness and adhesive strength of the coating.The denser the coating， the greater the hardness of the coating， and the dense structure could reduce the peeling of WC particles during friction， resulting in good wear resistance of the coating.The optimum processing parameters for rotating shaft repair were determined from these tests.After a run-in test of 1 000 h，the repaired rotating shaft exhibited no significant wear or damage，with the size change being less than 0.01 mm，and the product performance was found to meet the technical requirements.

The addition of trace Mo and Nb elements to the Fe-Cr-Al ferrite alloy of the accident tolerant fuel (ATF) cladding can play a role in solid solution strengthening and precipitation. The precipitated Laves phase distributes at the grain boundary and subgrain boundary, which can fix the grain boundary and hinder grain growth, improving the thermal stability of the alloy. According to another view, the pinning effect of the Laves phase is smaller than the solute drag effect (SDE) and does not contribute significantly. The phase field method was used to quantitatively simulate the hindrance of Mo and Nb solute elements to grain boundary migration in order to study SDE on grain boundary migration during grain growth. To model the effect of the solute elements on grain boundary migration, a polycrystalline phase field model and a solute drag additional term were introduced to the existing phase field model, and the specific expressions of these models were derived for simulation. The simulation results show that the phase field method can observe the unsteady solute separation process, in comparison to the classical steady-state SDE model. In addition, the distribution of solute at grain boundaries with different migration rates and the corresponding SDE dissipation energy at those rates are also obtained, and the action range of Nb and Mo element SDE is determined. The degree of solute segregation at the grain boundary is negatively related to the grain boundary migration rate. When the grain boundary migration rate is greater than 1×10-5 m/s, the segregation of Mo and Nb at the grain boundary tends to zero. The relationship between SDE dissipation energy and interface migration rate is parabolic, with a peak value of 69.7 J/mol at a rate of 1.124×10-6 m/s. When the interface migration rate is less than 1.124×10-6 m/s, the concentration distribution deviates from the equilibrium state and the dominant SDE dissipation energy increases. When the interface migration rate is greater than 1.124×10-6 m/s, the solute separates and the degree of segregation decreases, while the dominant SDE dissipation energy decreases. During the early stage of grain growth, the solute at the grain boundary is not in a saturated state and the interface migration rate is too high, resulting in no obvious SDE. At the same time, the high interface migration rate causes solute retention. The results of the study show that the model is suitable for simulating the SDE in the polycrystalline growth process, and can provide valuable information for a deeper understanding of the solute dragging process of Mo and Nb in materials and for material design and performance prediction.

Objective To investigate the expression and clinical significance of H3K27me3 in vascular hemangioma and malformation. Methods Paraffin-embedded tissue blocks from 244 patients with hemangioma and vascular malformation admitted in our hospital from January 2010 and June 2021 were collected. The expression levels of H3K27me3 and smooth muscle actin (SMA) in vascular endothelial and perivascular cells were detected by immunohistochemical SP assay, and its expression differences between hemangioma and vascular malformation was analyzed. Bioinformatics analysis was further applied to explore its potential role in anigodysplasia in combination of the results of SMA immunostaining. Receiver operating characteristic (ROC) curve was drawn to evaluate its diagnostic value in differentiation of hemangioma and vascular malformation. Results In vascular hemangioma, H3K27me3 expression was mainly restricted to vascular endothelial cells, with an expression rate of 50%~90%. However, in vascular malformations, it was expressed in vascular endothelial cells, with an expression rate of 30%~50%, and lost in perivascular cells. There were top 10 endothelium restricted genes derived from GSE21212 dataset based on concerning literatures. According to ChIP-seq data from ENCODE website, H3K27me3 was enriched in the SOX2 promoter of different endothelium lineages, and the molecular interaction of H3K27me3 and SOX2 may be associated with vessel development and differentiation. Conclusion The expression of H3K27me3 in vascular endothelial cells can be used as a candidate marker to distinguish hemangioma and vascular malformation. However, its expression in infantile hemangioma is immunologically heterogeneous.

The pore distribution characteristics of coal not only directly affect the gas storage and migration ability in coal seam, but also directly affect the development process of physical adsorption and chemical reaction between coal and oxygen. Therefore, in-depth study of the pore distribution characteristics of coal is conducive to the reasonable classification and evaluation of coal reservoirs, and then study and analyze the laws of gas storage and migration in coal seams and the low-temperature oxidation reaction mechanism of coal, improve the accuracy of gas content prediction and gas extraction efficiency, and describe the process of coal spontaneous combustion in detail. We have systematically summarized the current research theories and methods of pore distribution characteristics of coal through a large number of relevant literature investigations, and compared and analyzed various research theories and methods, pointed out their respective advantages and disadvantages. Finally, it is proposed that the next step can be carried out from three directions: accurate measurement of micro-pores and reasonable characterization at full scale, research on microscopic effects of coal pores, and establishment of accurate coal medium models.

Based on the systematic investigation, this paper summarizes the four important development stages of the prediction technology of mine gas emission in China from 1950s to now. It focuses on the basic principles, application scope, advantages and disadvantages of the source based prediction method, mine statistical method, gas geological mathematical model method, grey prediction method, neural network prediction method and combination prediction method. The main problems of each prediction method are analyzed in detail with the field application status. Finally, centering on the development goals of mine mechanization and intelligentization, three technological breakthroughs are proposed: improving the scientific selection of predictive parameters of source separation, promoting the modularization and integration of gas geological model prediction technology, and establishing information-based high-end fusion model, which points out the direction for future research on gas emission prediction technology.

The gas occurrence mechanism of deep coal seam is an important theoretical basis to guide the safe and efficient mining of deep coal and gas resources. Compared with the shallow coal seam, the occurrence environment of the deep coal seam has the characteristics of high stress, high temperature, high gas pressure and low permeability, which determines the unique characteristics of the deep gas occurrence and the technical problems faced by the deep resource output. We systematically reviewed the influence of stress, temperature, pressure and permeability on the gas occurrence laws of deep coal seam, pointed out the shortcomings of single physical field influence research, and made clear that the multi-field coupling environment is the objective condition for the study of gas mechanism of deep coal seam, and pointed out the direction for the study of gas occurrence mechanism of deep coal seam.

Objective To detect the expression of 4 progesterone receptor (PR) antibodies (EP2, SP2, 1E2, and 16) in non-specific invasive breast cancer (NSIBCs) and identify the optimal antibody for PR analysis and treatment planning for NSIBCs. Methods Immunohistochemistry was used to detect the expression of the 4 PR antibodies in a tissue microarray consisting of 195 tissue specimens of NSIBCs, and their constituent ratios with the expression of estrogen receptor (ER), the percentages of stained cells, staining intensity, Allred score (A-score) and consistency were compared. Results The constituent ratios of the 4 PR antibodies with ER (ER±/PR±) did not differ significantly in the 195 cases of NSIBCs (P>0.05). Regardless of the status of ER expression, the cases showed high rates of positivity or negativity for all the 4 PR antibodies at the same time (81.54%~90.77%) with good consistencies among the 4 antibodies (κ=0.634~0.804). Further analysis of the average number of stained cells, percentage of positive cells, staining intensity, and A-score of the 4 PR antibodies showed that all these indicators were significantly higher for 1E2 than for EP2, SP2, and 16 (P < 0.05), and were not significantly different among the latter 3 antibodies (P>0.05). Conclusion 1E2 has a higher positivity rate and expression intensity in NSIBCs than EP2, SP2 and RP16, and thus can serve as an ideal PR antibody for clinical pathology tests.

Coal mine safety standard is the basis of ensuring coal mine safety production, mine ecological environment safety and employees’ safety and health, preventing coal mine accidents and occupational hazards, and is also an important support for the implementation of coal mine safety production supervision and the establishment of safety development concept. In order to deeply understand the current situation of China’s coal mine safety standards, 853 current effective coal mine safety standards were collected and analyzed from the perspectives of standard level and nature, standard release year, standard for risk category, etc. The problems such as weak binding force of standards in current standard work were pointed out, and suggestions such as paying attention to overall planning and top-level design were proposed for reference to improve the coal mine safety standard work in China.

With intense industrialization and urbanization, soil heavy metal pollution in some areas of China has become a serious environmental problem, and draws great attention because of its potential threat to food safety and detrimental effects on the ecosystem. Jinghui irrigated area of Shaanxi (China) is a main grain production area and has a pivotal position in Chinese agricultural development. With the growing development of irrigated area, large numbers of agricultural pollutants, traffic exhaust and industrial wastes are released into the environment, probably leading to heavy metal pollution in soil. The accurate assessment of soil quality in the irrigated area is important for the reasonable use of soil resources, which has important theoretical and practical value for the maintenance of agro-ecosystem productivity. In this study, a total of 104 soil samples at depth 0-20 cm were collected (one sample per 3 km×3 km), and the content of eight heavy metals (including mercury, arsenic, cadmium, chromium, lead, copper, zinc and nickel) in samples was analyzed to assess their geo-spatial distribution in soil of Jinghui irrigated area. Multivariate statistics (Correlation analysis, principal component analysis and cluster analysis) and geostatistics methods (ArcGIS tools) were used to identify possible pollution sources of heavy metals. The results showed that the content of the Hg, As, Cd, Cr, Pb, Cu, Zn and Ni in soil of the study area averaged 0.091, 15.4, 0.25, 74.4, 27.2, 28.1, 81.1 and 36.6 mg kg-1, respectively. All of them were slightly higher than their corresponding natural background values of agricultural surface soil in Shaanxi reported in 1986, but below the threshold values of the National Environment Quality Standard for Soil (GB15618-1995). Geostatistical analysis showed that the spatial variability and structure were good with varying nugget-to-sill ratio. The nugget-to-sill ratio of Hg, Ni and As ranged from 25% to 75%, indicating the moderate spatial dependence among them. The nugget-to-sill ratio of Zn, Pb, Cd, Cu and Cr were all higher than 75%, indicating weak spatial correlations. Spatial distribution maps showed the similar characteristics behavior for Pb-Cu-Zn-Ni, and heavy metal content was high mainly in Jingyang county, Sanyuan county and Yanliang district. Multivariate analyses suggested that the Hg, Cd, Pb, Zn, Cu, As, Cr and Ni in soils may be mainly derived from anthropogenic activities. Principal component analysis coupled with cluster analysis revealed that the tested 8 heavy metals were mostly from three sources. Pb, Cu, and Zn were associated with transportation, Cr, As, Ni, and Cd came up with agricultural practices, while Hg was closely affected by industrial discharge. Soil environmental quality of Jinghui irrigated area remained good at present, but had a trend of increase towards heavy metal accumulation. Therefore, a comprehensive environmental management strategy should be strengthened in this area. [ABSTRACT FROM AUTHOR]

Bambusa emeiensis is one of the preponderant species of sympodial bamboos in Sichuan province of China, and has excellent fiber length and quality as raw materials for papermaking, textile and other industries. In this study, with the application of Illumina HiSeq™ 2000 platform, we analyzed transcriptome in B. emeiensis with different heights of 10, 50, 100 and 150 cm. A total of 69.28 M reads were obtained, and a sum up of 111 137 bands of Unigenes were acquired following de novo stitching, assembly and clustering, among which there were 63 094 bands that had been integrated in the COG, GO, KEGG, Swiss-Prot and Nr databases using annotated methods. These Unigenes not only had general functions, such as transcription and signal transduction, but were also involved in sucrose transport and metabolism, secondary metabolites and cell wall biosynthesis. There was significant difference regarding the expression of cellulose synthase gene in B. emeiensis at different heights, relevant genes were found that might be responsible for the regulation of the growth and development of B. emeiensis as well as the biosynthesis of cellulose and lignin. Our findings could provide some elementary theories for breed improvement of B. emeiensis.