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Black phosphorus （BP） nanosheets have a special folded structure， which gives them an adjustable band gap， transmission anisotropy， and photoluminescence. These unique properties make BP nanosheets widely used in the construction of metal ion sensors and show great application potential in environmental monitoring and other research fields. In this paper， the preparation methods of BP nanosheets and their applications of different sensors in detecting heavy metal ions were introduced. Firstly， different preparation methods for BP nanosheets were introduced based on the “top-down” and “bottom-up” methods， and their advantages and disadvantages were summarized. Then， the research progress of BP nanosheets based field effect transistor （FET） sensors， electrochemical sensors， and photochemical sensors for the detection of heavy metal ions were described in detail. Among these sensors， the FET sensor shows an excellent detection limit， the electrochemical sensor has advantages of short response time and simple operation. The photochemical sensor shows a wider detection range than that of others. Furthermore， it is concluded that the types of heavy metal ions that BP nanosheets based sensors can detect are relatively limited， and the stability and selectivity need to be further improved. Finally， in view of the challenges faced by BP nanosheets for constructing different types of heavy metal ion sensors， we should develop low-cost and high-quality BP nanosheets preparation methods， and structure optimization and functional modification of BP nanosheets. In the aspect of expanding the application of BP nanosheets for the detection of heavy metal ions， it is expected to make a breakthrough in the practical applications by combining with novel technology.

Objective To investigate the effect of resistance exercise on self-management ability, vascular diastolic function and atherosclerosis in patients with hypertension. Methods A total of 160 patients with hypertension treated in Sinopharm Dongfeng General Hospital from December 2019 to January 2022 were enrolled in this study. Patients were divided into study group (n=80) and traditional group (n=80) by random number table method. The traditional group was given routine aerobic exercise training based on drug therapy, and the research group was given resistance exercise training based on traditional therapy. Patients in both groups received intervention for 3 months, and the changes of vascular endothelial diastolic function and atherosclerosis were compared and analyzed before and after training. Results After training , the systolic blood pressure and diastolic blood pressure of the two groups decreased significantly compared with those before training (P＜0.05), and the study group was significantly lower than the traditional group (P＜0.05). The scores of self-management ability (45.28±3.17, 40.10±2.22) in the study group and traditional group were significantly higher than those before training (31.48±3.18, 31.54±2.58); The score of self-management ability in study group was significantly lower than that in traditional group (t=141.972, P＜0.05). The serum levels of lipoprotein-associated phospholipase 2 (Lp-PLA2) and homocysteine (Hcy) in two groups decreased significantly compared with those before training (P＜0.05)，and the levels of serum Lp-PLA2 and Hcy in the study group were significantly higher than those in the traditional group (P＜0.05). The change rate of artery diameter and the change rate of artery diameter of endothelium-dependent vasodilation function in the two groups were significantly higher than those before training, and the study group was significantly higher than the traditional group (P＜0.05). There was no significant difference in carotid intima-media thickness between the two groups after training and before training, and there was no significant difference between the study group and the traditional group (P＞0.05). Conclusion Resistance exercise can improve vascular endothelial relaxation function and atherosclerosis status, inhibit the expression of Lp-PLA2 and Hcy, reduce blood pressure continuously, and improve the self-management ability of patients with hypertension.

With the gradual maturity and application of digital assembly technology，the interchangeability design adapting to digital quantity transfer is of significant practical significance for improving the efficiency of aircraft control surface design，stabilizing assembly quality and reducing maintenance cost. Taking the interchangeability design of a certain type of aircraft control surface as the research object，the design points are analyzed according to the requirements of the control surface interchangeability，and the interchangeability design process coordinated with digital assembly is established. The structural elements of the interchangeability design are analyzed from the configuration characteristics of the control surface. The technical approach to realize the interchangeability of the control surface is proposed，and the corresponding reference indexes are given. Combined with the test method of aircraft interchangeability，the aileron of a certain type of aircraft is taken as an example to analyse and design the interchangeability of the control surface，which is verified by the actual assembly inspection. The results show that the design process of control surface interchangeability is feasible，which can satisfy the interchangeability requirements

The mining disturbance between multiple working faces will induce rock burst disaster, and regional harmonic mining is one of the key means to prevent this kind of rock burst. In order to verify the rationality and effectiveness of regional harmonic mining to prevent rock burst, taking Yima Mining Area where rock burst occurs frequently as an example, based on the harmonic mining principles and parameter values obtained from simulation, the harmonic mining scheme in the area between Yuejin and Changcun coal mines is formulated, and the effect of harmonic mining is evaluated by comparing the stress transfer characteristics and rock burst characteristics in the area with different harmonic degrees. The results show that the thickness of coal seam and huge thick conglomerate of Yuejin 23092 face and Changcun 21162 face are smaller in the area between Yuejin and Changcun coal mines. The width of coal pillar between 23092-21162 and 21170-21162 working faces are larger, and the horizontal distance and vertical offset between the two faces are further, so the 23092 and 21162 working faces between the two coal mines are the optimal continuous working faces. The degree of harmonic mining in the area between Yuejin and Changcun coal mines is higher than that of Gengcun and Qianqiu coal mines. The frequency and intensity of stress transfer caused by rock burst and mining among working faces are all significantly reduced with harmonic mining, and the range of stress transfer significantly is reduced, so the effect of harmonic mining is obvious.

In the test of the flexural performance of the honeycomb sandwich structure,due to the different test methods,there is a situation that the data dispersion is large,which causes the reliability to be reduced,which is not conducive to the evaluation of the true performance of the structure.The flexural performance of the honeycomb sandwich structure is studied by flexural measurement method(ASTM method);flexural performance average method analysis and lateral pressure method,and the discrete difference of data is compared to evaluate the effectiveness of the three test methods.Through the test and analysis of the test pieces,the flexural performance data of the honeycomb sandwich panel is obtained.The results show that:the dispersion coefficient of the flexural performance data measured according to the ASTM method is greater than 0.1,which conceals the authenticity of the test results;according to the mean value of the flexural performance,the method substituting the honeycomb core shear modulus into the relational formula to solve the flexural performance of the sandwich structure,the dispersion coefficient is less than 0.09,the result is credible;according to GB/T 1454—2005 lateral compression method,the lateral compression modulus of the sandwich structure is lower than that of flexural test,considering the influence of the stiffness of the panel itself,the result of the lateral pressure method is more authentic and the dispersion coefficient is less than 0.07.The credibility is further improved.

The lift device design of laminar flow wing can reduce drag and noise.By combining the low resistance laminar flow area with the high-efficiency lift device and adopting the effective shape design and appropriate structure selection,the expansion of laminar flow area during cruise and the improvement of lift effect during take-off and landing can be realized,and the body noise can be significantly reduced.According to the development needs of green aviation,the technical characteristics of laminar wing and lifting device are analyzed,the design method of the lifting device under the condition of laminar flow wing is described,the application status of structure shape,motion mechanism and auxiliary device is systematically introduced.On this basis,the key research contents for realizing the adaptive adjustment of the lifting device are summarized,and the future development direction and ideas of the lift device are given.

The output shaft is one of the core components of the gearbox of an oil rig,The reliability of the output shaft directly affects the service life and economic benefit of the oil rig. In this paper,the stress analysis of the structure of the original output shaft is carried out by using the finite element method; The optimization and improvement scheme is put forward,and the stress of the output spindle before and after the improvement is compared and analyzed,According to the analysis results,the final improvement scheme of the output shaft is determined,The results show that the safety factor of the improved output shaft is significantly improved,The modal of the output shaft is analyzed by finite element method,It is verified that the working speed of the output shaft is within the safe range. The research in this paper has certain guiding significance to improve the performance of oil rig output shaft.

This paper proposed an analysis scheme for the multiple fracture failure of the gear rotor of the melt pump used in the key equipment of a chemical plant.Through the analysis of damage fracture analysis,material property analysis,microstructure analysis and strength checking,the root causes of failure were found,the conclusion of failure was concluded and the improvement scheme was proposed.The analysis results show that the gear rotor of molten pump has some defects in the process of design and machining under complicated conditions,which leads to its frequent failure during operation.By changing its structure,reducing stress concentration,the selection of good materials,improve production processes and other ways to effectively improve the performance of the shaft to meet their functional needs.The results of this research could provide certain reference value in improving the service performance of key transmission parts,especially gear type transmission shafts.

In order to find out the cause of the fracture of the cutting spindle as one of the key components of a cantilever roadheader, and to solve this fracture problem, this paper analyzes it in multiple ways and proposes an improved scheme. Through the analysis of fracture surface macro-morphology, material chemical composition, mechanical properties, microstructure and finite element stress of the cutting spindle, the failure conclusion is drawn and the corresponding improvement scheme is put forward. The results show that the cutting spindle in the actual complex working conditions, due to machining and heat treatment in the process of shortcomings, as well as the use of abnormal operation, resulting in the operation of the stress concentration in the greater position of fracture failure. According to the failure reasons, the corresponding improvement schemes are put forward: by optimizing the structure and improving the processing, reducing the stress concentration, improving the heat treatment process, improving its mechanical properties and other methods to improve the performance of the shaft to meet its functional requirements. The results of this study can provide a good reference value in solving the problem of failure of shaft transmission parts and improving the performance of shaft transmission parts.

The support methods and life calculation methods of the planet gear bearings in planetary reducer are discussed. Combining with dual-mode cutting reducer The example calculations are carried out.Several factors that affect the bearing life are simulated and analyzed by using KISSsoft. Finally,the considerations for the design of the planet gear bearing for Cutting reducer are put forward and the reference for similar design in the future is provided.

To investigate the effect of Ni-P coating on the interfacial reactions in Cu/Al dissimilar metal brazing, a chemical plating method was employed to nickel plate T2 copper, followed by brazing of the Cu/Al joints using the induction brazing technique with BAl88Si flux-cored filler metal. Scanning electron microscopy and electron backscatter diffraction were utilized for microstructural observation and phase analysis of the joints. Mechanical testing was performed to analyze the influence of the coating on the microstructure and mechanical properties of the Cu/Al joints, while also exploring the interface formation mechanism of different brazing joints during the brazing process. The results reveal the formation of intermetallic compounds Cu9Al4 and CuAl2 at the interface of uncoated joints, whereas intermetallic compounds Al2Ni and Al3Ni are formed at the interface of the coated joints. The tensile strength of uncoated joints reaches to 56.4 MPa, outperforming that of coated joints. Brittle fractures occurre in all joints, with the fracture location transitioning from the interface of CuAl2 and the α-Al solid solution in uncoated joints to the Al3Ni intermetallic compound in coated joints. [ABSTRACT FROM AUTHOR]

Objective To investigate the hemostatic effect of transanal prostatic resectoscope technology on massive rectal bleeding after transrectal prostate biopsy. Methods From May 2016 to March 2022, 483 patients underwent transrectal prostate biopsy, 5 patients of them had hemodynamic deterioration due to massive rectal bleeding within 3 to 8 hours after operation. After active rehydration and blood transfusion, transanal prostatic resectoscope technology was applied to check the biopsy region and coagulate the active bleeding point. After hemostasis, the anal tube was retained for drainage for 24 to 72 hours and then removed. Results The average bleeding volume was about 440 mL (400 mL -1 000 mL) ; Average blood transfusion volume; RBC 2. 0 U/case, homoplasma 520 mL/case; The average operation time was 25 minutes (20-30 minutes) ; Rebleeding, local infection, hyponatremia and hypokalemia was not observed; The mean hospital stay was 4. 5 days (3-7 days) . Conclusion Transanal prostatic resectoscope technology is an effective method for rapid control of massive rectal bleeding after transrectal prostate biopsy. This method has obvious advantages in direct vision, clea vision, visible bleeding point, accurate and reliable hemostasis. [ABSTRACT FROM AUTHOR]

A fast reconstruction algorithm based on inner product optimization and sparsity updating constraint was proposed for OFDM system channel estimation when the number of channel paths was unknown. By constructing and updating the selection vector, the inner product operation was reduced by using the atoms corresponding to the non-zero index of the selection vector. The atoms were optimized based on compressed sampling and backtracking strategies, and the channel estimation was completed by matching pursuit. The sparsity update and the stop condition for the algorithm was achieved by the energy difference between the two adjacent channel estimation so as to ensure fast convergence of the algorithm. The simulation results show that the proposed algorithm has better channel estimation performance than the least square algorithm, minimum mean square error algorithm, sparsity adaptive matching pursuit algorithm and adaptive regularized compressed sampling matching pursuit algorithm, and consumes less channel estimation time than the two adaptive methods. [ABSTRACT FROM AUTHOR]

Focusing on the poor clutter suppression performance of the conventional space-time adaptive processing (sTAP) method caused by range migration and Doppler migration of clutter with hypersonic platform, this paper firstly constructs a bidimensional space-time model of clutter of hypersonic platform and analyzes the clutter properties, which show that the heterogeneous clutter distribution is severer and the Doppler spectrum of clutter is broadened further compared wtth that of the slow velocity platforms Furthermore, the heterogeneous distribution and Doppler spread are reacted to the positions of scatters and the number of pulses. Finally, a clutter suppression method, which corrects the range migration of clutter by keystone rransform and compensates the increment of clutter Doppler by compensation matrix, is proposed. simulation results show that the proposed method can narrow the notch for clutter suppression and obviously improve the determine performance of moving targets in the main lobe area. [ABSTRACT FROM AUTHOR]

Sharing of wireless channel causes mutual interference among user equipment in wireless networks. In this paper, the problem of uplink interference suppression in the architecture of C-RAN wireless network is investigated. Taking advantage of the centralized processing in the C-RAN architecture, the correlations of the signals from each RRU are analyzed, based on which we proved that under certain condition, interference can be eliminated by utilizing the correlations a-mong signals. Moreover, we proposed a correlation matrix among network users that was established based on signals from each user to their nearby RRU. Then, the interference cancellation matrix was solved by the correlation matrix. We utilized the achieved interference cancellation matrix to process the uplink signals for the elimination of uplink interference. Simulation results by applying 4QAM and 16QAM modulation schemes indicate that, our method significantly improves the bit error rate compared to the traditional reception methods. In addition, the descent of bit error rate becomes faster as the background noise decreases. [ABSTRACT FROM AUTHOR]

Smart tourism has become increasingly popular in mainland China since Qiwei Shao, the director of the China National Tourism Administration, called for developing the tourism industry over the next 10 years by means of smart tourism in July 2011. Since then, different types of events and activities have been held by the name of "smart tourism", leading to some misunderstanding of the term. What, then, is smart tourism? How can it be defined? Although some researchers have expressed their understanding of the term in papers or presentations, there is still a long way to go before an accepted meaning can be reached. Some years ago outside China, some researchers and practitioners defined smart tourism according to their own understanding. In the United Kingdom, it was defined in 2009 as "the use and application of technology in the tourism sector" by "smart tourism organizations". The Tourism Industry Association of Canada in 2000 provided the following definition: "smart tourism is simply taking a holistic, long-term, sustainable approach to planning, developing, operating and marketing tourism products and businesses." In the West world, it seems that smart tourism is not an independent concept but an adjective used in such ways as smart tourism information system, smart travel system, smart travel service advisor, and smart travel planning. Smart tourism is still a new concept, both theoretically and practically, in mainland China. According to the Baidu online encyclopedia, smart tourism is "the use of cloud computing, networking, and other new technologies with a portable terminal via the Internet or mobile Internet, in achieving information on tourism resources, tourism economy, tourist activities, etc. In this regard, tourists can acquire information in a timely manner to arrange and adjust their travel plans. "This is not a theoretical definition but a descriptive notion. In the present study, based on an analysis of the definitions used by most scholars and organizations, smart tourism is defined as a ubiquitous tourist information service used by individual tourists during their trips. The definition provided by this study intends to emphasize smart tourism as an individual tourist support system with a carrier, information services, and ubiquitous technology; this is identified as the core area in the concept of smart tourism. This paper observes that great changes have taken place in tourists' behavior, tourism marketing, tourism management, and also the tourism service mode. The new information service offered by smart tourism and that of a traditional tourist information service are quite different with respect to three areas--destinations, enterprises, and tourists. This study compares and contrasts the particular characteristics of both traditional tourist information services and the information services of smart tourism. This paper presents recommendations for smart tourism and examines the future for smart tourism in China in terms of research and practical fields. For the Chinese tourism market, the use of new technology has become increasingly important in improving tourist satisfaction, reducing the costs of tourism, and increasing the efficiency of tourist transactions. Smart tourism represents a new direction for new technology directed at tourism, and it will have a significant influence on tourist destinations, enterprises, and also tourists themselves. Smart tourism represents a prospective direction for the future Chinese tourism industry. This paper indicates that unique value can be achieved by merging smart tourism and tourism informationization, which can be seen as an area of future development for smart tourism. [ABSTRACT FROM AUTHOR]

Background The prevalence of hypertension in population is still increasing by year, and the significant increase in the prevalence of chronic diseases caused by aging of the population results in a serious medical burden. There are still about 450 million people in China who use solid fuels for cooking or heating, causing indoor air pollution as an important public health problem in China. At present, the relationship between solid fuels use and the risk of hypertension in Chinese older adults still remains unclear. Objective To analyze the association between solid fuels use and the risk of hypertension in older adults in urban and rural areas of China through a prospective cohort study, so as to provide a theoretical basis for the prevention and treatment of hypertension in the elderly. Methods This study is a prospective cohort study. Data were obtained from 2011 to 2018 China Longitudinal Healthy Longevity Survey (CLHLS) by using baseline questionnaire and physical examination. A total of 1 453 non-hypertensive older adults aged 65 years and above from 2011 to 2012 cohort were included in the study, and the occurrence of hypertension during follow-up was considered as the outcome indicator, follow-up as of 2018-12-31. The included subjects were divided into the clean fuel (electrical appliances such as induction cooker, pipeline natural gas, solar energy) group (n=654) and solid fuel (charcoal, kerosene, coal, firewood) group (n=799). Multivariate Cox proportional hazard regression model was used to analyze the association between cooking with solid fuels and the risk of hypertension. Results A total of 1 453 non-hypertensive older adults at baseline with an average age of (77.6±8.8) years and a median follow-up of 7 years, and a total of 838 people developed hypertension at the outcome. The results of this study showed that the proportion of cooking with solid fuels in rural areas was significantly higher than that in urban areas (70.3% vs. 1.1%, P

In recent years, as coal mining strategy has moved westward in China, rockburst has now become the most severely affected coal mine disaster in Ordoes area. This paper takes Hongqingliang Coal Mine in Tarangole Mining Area of Ordos coalfield as the background, and conducts a systematic study on the prevention and control of rockburst under the conditions of deep mining in Tarangole Mining Area. The research shows that the deep mining in Tarangole Mining Area is under the geological conditions of “weak cemented overburden + high strength coal”. The deep mining rock burst in Tarangole Mining Area is caused by the accumulation of a large amount of elastic energy in the hard coal body due to high-intensity mining. The prevention and control strategy of rock burst combining reducing coal strength, controlling pushing speed, optimizing section coal pillar size, and strengthening support was proposed. Hongqingliang Coal Mine adopts comprehensive measures such as drilling pressure relief, control of mining speed, and strengthening of mining roadway support. The on-site microseismic monitoring data confirmed the effectiveness of the prevention and control of rock burst and realized safe and efficient mining of the mine.

In order to solve the problems of ecological environment caused by the shortage of filling materials and solid wastes in the goaf of coal mine, the paper puts forward some suggestions to solve these problems, in the paper, influencing factors of paste filling body strength were analyzed, and sample strength of filling body was determined by orthogonal test, the correlation between the influence factors and the strength of the filling body was determined with grey relational analysis method, and an improved BP strength prediction model was built, in which the factors affecting the strength of solid waste paste filling are input layer and the strength of the filling body is output layer. The strength test data obtained from orthogonal test were used as training samples and test samples of the network, the fitting ability and generalization ability of network data were tested by analog simulation. Test results show that the established prediction model has fast convergence speed and high accuracy, and its prediction accuracy reaches 93.75%, which indicates accurate prediction of the filling body strength can be realized.

In order to study the similarities and differences of mechanical and internal fine view of the structure between artificial sandstone and deep coal seam roof sandstone, artificial sandstone of different material proportions and deep roof sandstone in No. 12 Coal Mine of Pingmei Company were measured by a series of tests, including acoustic wave velocity test, uniaxial compression test, CT scanning, and high-pressure mercury injection test. The experimental results show that the greater the particle size and the higher the mass ratio of the quartz sand, the greater the elastic modulus of the artificial sandstone. For the artificial sandstone, aggregate and pore structure are uniform distribution, both the porosity and permeability are negatively correlated with the mass fraction of clay. The elastic modulus of roof sandstone is between large-grained and coarse-grained artificial sandstone, and the density distribution of rock mass is more discrete. The permeability and pore radius distribution are 1 to 2 orders of magnitude smaller than that of artificial sandstone. Comparison results show that artificial sandstone can better simulate on mechanical properties of deep roof sandstone, and on the pore structure artificial sandstone and deep roof sandstone has bigger difference.

Objective: To evaluate the effects of casein osphopeptide-amorphous calcium phosphate (CPP-ACP) in preventing enamel demineralization., Methods: Enamel blocks were prepared from premolars extracted from orthodontic patients. The specimens were treated for 30 min daily for 7 days with one of the following agents: deionized water (negative control), CPP-ACP paste, and NaF solutions (positive controls) (0.2% and 2%). After the treatments, the specimens were immersed in a demineralizing solution (pH 4.5) for 7 days. The morphology and depth of the lesion were observed using scanning electron microscopy, and the content of Ca, P, Mg in the demineralized enamel was measured by electron probe micro-analyzer., Results: The demineralization rates in all the treatment groups were significantly smaller than those in the control group after 7 days of demineralization., Conclusion: The application of CPP-ACP to the enamel surfaces can inhibit enamel demineralization with an equivalent effect to 0.2% NaF.

Objective: To analyze the capsule related surface properties of Porphyromonas gingivalis (Pg) isolates., Methods: The transmission electron microscopy (TEM) was used to observe the capsule structure and the capsule thickness of 2 type of strains and 5 clinical isolates. Microbial adhesion to hydrocarbons (MATH) assay was used to qualitatively assess the hydrophobicity of each strain, and the capacities of these strains were investigated by autoaggregation assay.Ninety-six well biofilm assay and confocal laser scanning microscopy (CLSM) were applied to quantify and observe the biofilm produced by each strain., Results: TEM showed the variety of capsule thickness of these strains.Virulent type strain W83 possessed thicker capsular structure than less-virulent type strain ATCC33277. The SJD4 possessed thicker capsule than other clinical isolates, followed by SJD11, SJD5, SJD2, and SJD12.Strains W83, SJD4, SJD11, with thicker capsule, were much more hydrophilic with lower MATH percentage, in accordance with a slow autoaggregation in incubation during a period of 240 min. Compared with W83, the hydrophobicity of strains ATCC33277, SJD5, SJD2, and SJD12, with thinner capsule, showed increased MATH percentage and autoaggregations. All clinical strains developed biofilm with different absorbance compared with type strains. The CLSM observation showed biofilm thickness of each strain, ranged from (14.74 ± 4.99) to (24.13 ± 5.45) µm. Strain W83 and SJD11 showed notable poor biofilm formation, while others developed dense and mature biofilm., Conclusions: There was a certain degree of linkage between the Pg capsule thickness and surface properties diversity.

Objective: To observe the clinical efficacy of shensong yangxin capsule (SYC) on ventricular premature beat (VPB) differentiated in TCM as palpitation of Qi-yin deficiency syndrome or Xin collateral stagnation syndrome, and cardiovascular autonomic nervous function in patients with coronary heart disease (CHD)., Methods: The randomized, double-blind, parallel contrast method was adopted, patients were randomly assigned by 3:1 ratio into two groups. One hundred and sixty-five patients in SYC treated group and 56 in the control group (treated with Xinlvning tablet), and the therapeutic course for both groups was 4 weeks., Results: The clinical efficacy on VPB and in improving TCM syndromes was better in SYC group than that in the control group (P < 0.01). After treatment, the heart rate variability (HRV) and QT dispersion in the two groups were improved in a certain degree. The changes of SDNN, SDANN, SDNN Index and PNN50 in the two groups were significantly different (P < 0.05, P < 0.01), the efficacy in the treated group was superior to that in the control group., Conclusion: SYC has definite effect on VPB and TCM Syndromes, it can obviously meliorate the activity of cardiovascular autonomic nervous system in the patients with CHD.