This study proposes a batch rapid quantitative analysis method for multiple elements by combining the advantages of standard curve(SC)and calibration-free laser-induced breakdown spectroscopy(CF-LIBS)technology to ach...This study proposes a batch rapid quantitative analysis method for multiple elements by combining the advantages of standard curve(SC)and calibration-free laser-induced breakdown spectroscopy(CF-LIBS)technology to achieve synchronous,rapid,and accurate measurement of elements in a large number of samples,namely,SC-assisted CF-LIBS.Al alloy standard samples,divided into calibration and test samples,were applied to validate the proposed method.SC was built based on the characteristic line of Pb and Cr in the calibration sample,and the contents of Pb and Cr in the test sample were calculated with relative errors of 6%and 4%,respectively.SC built using Cr with multiple characteristic lines yielded better calculation results.The relative contents of ten elements in the test sample were calculated using CF-LIBS.Subsequently,the SC-assisted CF-LIBS was executed,with the majority of the calculation relative errors falling within the range of 2%-5%.Finally,the Al and Na contents of the Al alloy were predicted.The results demonstrate that it effectively enables the rapid and accurate quantitative analysis of multiple elements after a single-element SC analysis of the tested samples.Furthermore,this quantitative analysis method was successfully applied to soil and Astragalus samples,realizing an accurate calculation of the contents of multiple elements.Thus,it is important to advance the LIBS quantitative analysis and its related applications.展开更多
A novel adaptive detector for airborne radar space-time adaptive detection （STAD） in partially homogeneous environments is proposed. The novel detector combines the numerically stable Krylov subspace technique and d...A novel adaptive detector for airborne radar space-time adaptive detection （STAD） in partially homogeneous environments is proposed. The novel detector combines the numerically stable Krylov subspace technique and diagonal loading technique, and it uses the framework of the adaptive coherence estimator （ACE）. It can effectively detect a target with low sample support. Compared with its natural competitors, the novel detector has higher proba- bility of detection （PD）, especially when the number of the training data is low. Moreover, it is shown to be practically constant false alarm rate （CFAR）.展开更多
Two immunomodulatory polysaccharides(Vp2a-Ⅱ and Vp3) were isolated and identified from Apocynum venetum L. flowers, and their innate immune-stimulating functions and working mechanisms were evaluated in RAW264.7 cell...Two immunomodulatory polysaccharides(Vp2a-Ⅱ and Vp3) were isolated and identified from Apocynum venetum L. flowers, and their innate immune-stimulating functions and working mechanisms were evaluated in RAW264.7 cells. Both the level of released nitric oxide(NO) and expression of inducible nitric oxide synthase(iNOS) m RNA were significantly enhanced in the RAW264.7 macrophages cells treated by Vp2a-Ⅱ and Vp3. Vp2a-Ⅱ(100–800 μg/m L) and Vp3(400 μg/mL) could significantly increase the phagocytic activity of RAW264.7 cells and the secretion and m RNA expression of TNF-α and IL-6 in a concentrationdependent manner through affecting mitogen-activated protein kinase(MAPK) activity and nuclear factor κB(NF-κB) nuclear translocation. Vp2a-Ⅱ might activate the MAPK signaling pathways and induce the nuclear translocation of NF-κB p65, whilst Vp3 likely activated the NF-κB and MAPK signaling pathways without influencing the p38 MAPK route.展开更多
The aerodynamic noise of high-speed trains passing through a tunnel has gradually become an important issue.Numerical approaches for predicting the aerodynamic noise sources of high-speed trains running in tunnels are...The aerodynamic noise of high-speed trains passing through a tunnel has gradually become an important issue.Numerical approaches for predicting the aerodynamic noise sources of high-speed trains running in tunnels are the key to alleviating aerodynamic noise issues.In this paper,two typical numerical methods are used to calculate the aerodynamic noise of high-speed trains.These are the static method combined with non-reflective boundary conditions and the dynamic mesh method combined with adaptive mesh.The fluctuating pressure,flow field and aerodynamic noise source are numerically simulated using the abovemethods.The results showthat the fluctuating pressure,flow field structure and noise source characteristics obtained using different methods,are basically consistent.Compared to the dynamic mesh method,the pressure,vortex size and noise source radiation intensity,obtained by the static method,are larger.The differences are in the tail car and its wake.The two calculation methods show that the spectral characteristics of the surface noise source are consistent.The maximum difference in the sound pressure level is 1.9 dBA.The static method is more efficient and more suitable for engineering applications.展开更多
Compounds with regulating glucose metabolism and improving insulin resistance(IR)activity are abundant in nature and can be obtained from several sources.They have high potential to be used to treat diabetes mellitus....Compounds with regulating glucose metabolism and improving insulin resistance(IR)activity are abundant in nature and can be obtained from several sources.They have high potential to be used to treat diabetes mellitus.These compounds isolated from natural plants can be classified seven categories:terpenoids,alkaloids,quinones,flavonoids,phenols,phenyl propanoids,steroids,and other types of compounds.They exert biological effects by different ways and mechanisms.This review illustrated the potential natural products as a rich resource in regulation of glucose metabolism and IR,as well as their mechanisms.展开更多
With the rapid development of technology,processing the explosive growth of meteorological data on traditional standalone computing has become increasingly time-consuming,which cannot meet the demands of scientific re...With the rapid development of technology,processing the explosive growth of meteorological data on traditional standalone computing has become increasingly time-consuming,which cannot meet the demands of scientific research and business.Therefore,this paper proposes the implementation of the parallel Clustering Large Application based upon RANdomized Search(CLARANS)clustering algorithm on the Spark cloud computing platformto cluster China’s climate regions usingmeteorological data from1988 to 2018.The aim is to address the challenge of applying clustering algorithms to large datasets.In this paper,the morphological similarity distance is adopted as the similarity measurement standard instead of Euclidean distance,which improves clustering accuracy.Furthermore,the issue of local optima caused by an improper selection of initial clustering centers is addressed by utilizing the max-distance criterion.Compared to the k-means clustering algorithm already implemented in the Spark platform,the proposed algorithm has strong robustness,can reduce the interference of outliers in the dataset on clustering results,and has higher parallel performance than the frequently used serial algorithms,thus improving the efficiency of big data analysis.This experiment compares the clustered centroid data with the annual average meteorological data of representative cities in the five typical meteorological regions that exist in China,and the results show that the clustering results are in good agreement with the meteorological data obtained from the National Meteorological Science Data Center.This algorithm has a positive effect on the clustering analysis of massive meteorological data and deserves attention in scientific research activities.展开更多
The closed-loop wireless power transfer(WPT)system can realize constant voltage output in the presence of perturbation.However,the parameter design of the controller is a difficult problem.The traditional trial-and-er...The closed-loop wireless power transfer(WPT)system can realize constant voltage output in the presence of perturbation.However,the parameter design of the controller is a difficult problem.The traditional trial-and-error method is time-consuming and difficult to find optimal parameters.A parameter optimization strategy of control systems for uncertain WPT systems using the modified genetic algorithm(MGA)is proposed.Firstly,because the system has different characteristics at different periods,the simulation process is divided into three stages.The first one is the start-up stage,in which we mainly consider the overshoot and the rate of the voltage rise.The second one is the tracking stage,in which the tracking time and switching loss are mainly considered.The third one is the stabilisation stage,in which the steady-state error and switching loss are mainly considered.Secondly,three cost functions are designed according to the characteristics of the three stages,and then the optimal controller parameters of each stage are obtained by using MGA.Finally,the effectiveness of the proposed method is verified by simulation.The optimization results show that compared with the previous parameter optimization method,the optimal controller parameters obtained by the proposed method make the WPT system achieve better performance.展开更多
Background:The nitrogen isotope natural abundance(δ^(15)N)provides integrated information on ecosystem N dynamics,and carbon isotope natural abundance(δ^(13)C)has been used to infer how water-using processes of plan...Background:The nitrogen isotope natural abundance(δ^(15)N)provides integrated information on ecosystem N dynamics,and carbon isotope natural abundance(δ^(13)C)has been used to infer how water-using processes of plants change in terrestrial ecosystems.However,howδ^(13)C andδ^(15)N abundances in plant life and soils respond to N addition and water availability change is still unclear.Thus,δ^(13)C andδ^(15)N abundances in plant life and soils were used to investigate the effects of long-time(10 years)N addition(+50 kg N·ha^(−1)·yr^(−1)and precipitation reduction(−30%of throughfall)in forest C and N cycling traits in a temperate forest in northern China.Results:We analyzed theδ^(13)C andδ^(15)N values of dominant plant foliage,litterfall,fungal sporophores,roots,and soils in the study.The results showed thatδ^(15)N values of foliage,litterfall,and surface soil layer’s(0–10 cm)total N were significantly increased by N addition,whileδ^(15)N values of fine roots and coarse roots were considerably decreased.Nitrogen addition also significantly increased theδ^(13)C value of fine roots and total N concentration of the surface soil layer compared with the control.The C concentration,δ^(13)C,andδ^(15)N values of foliage andδ^(15)N values of fine roots were significantly increased by precipitation reduction,while N concentration of foliage and litterfall significantly decreased.The combined effects of N addition and precipitation reduction significantly increased theδ^(13)C andδ^(15)N values of foliage as well as theδ^(15)N values of fine roots andδ^(13)C values of litterfall.Furthermore,foliarδ^(15)N values were significantly correlated with foliageδ^(13)C values,surface soilδ^(15)N values,surface soil C concentration,and N concentrations.Nitrogen concentrations andδ^(13)C values of foliage were significantly correlated withδ^(15)N values and N concentrations of fine roots.Conclusions:This indicates that plants increasingly take up the heavier 15N under N addition and the heavier 13C and 15N under precipitation reduction,suggesting that N addition and precipitation reduction may lead to more open forest ecosystem C and N cycling and affect plant nutrient acquisition strategies.展开更多
Recently,we read with interest the findings of Zhang et al.1 of the long-term bone consequences in severe acute respiratory syndrome(SARS)patients.Their conclusion suggested that pulmonary damage and femoral head necr...Recently,we read with interest the findings of Zhang et al.1 of the long-term bone consequences in severe acute respiratory syndrome(SARS)patients.Their conclusion suggested that pulmonary damage and femoral head necrosis could be halted and reversed in SARS patients during the 15-year follow-up.These results have very important implications for the treatment and health utility evaluation of coronavirus disease 2019(COVID-19).However,they did not explore the reasons for the reversal of femoral head necrosis after large doses of steroid pulse therapy,which may affect our understanding with regard to the treatment of COVID-19 patients.展开更多
Background: There is very limited data available about the epidemiology trial on chronic diseases comprehensive intervention. The aim of this study was to assess the effect of comprehensive intervention on chronic dis...Background: There is very limited data available about the epidemiology trial on chronic diseases comprehensive intervention. The aim of this study was to assess the effect of comprehensive intervention on chronic diseases in Baoji and provide basis for the improvement of chronic diseases intervention measures. Methods: Using four stages stratified random sampling method, comprehensive intervention measures were implemented on intervention group (575 individuals) respectively aimed at three crowds of whole population, high risk population and chronic diseases patients. The control group (782 individuals) did not receive special treatment. Two groups were evaluated effect after one year observation. Results: The chronic diseases prevalence rate of whole population in intervention group was lower than that in control group (P < 0.05), the blood pressure level and smoking proportion of high risk population in intervention group were lower than in control group (P < 0.05), and the blood pressure, blood glucose control rate of chronic diseases patients in intervention group were higher than in control group (P < 0.05). Conclusion: Comprehensive intervention could prevent the rise of chronic diseases prevalence. The intervention is effective in reducing or halting risk factors of high risk population, particularly in controlling blood pressure, blood glucose of patients. We should establish government leading, department cooperation, social participation, longtime and classified comprehensive intervention mechanism of chronic diseases. We believe that whole population should control the risk factors, high risk population should early diagnosis and treatment, chronic diseases patients should normalized management, and it could be applied in other counties.展开更多
Single-atom alloys(SAAs)have gained significant attention due to their remarkable atomic utilization efficiency,interactions between single atoms(SAs)and metal supports,and free-atom-like electronic structure of dopan...Single-atom alloys(SAAs)have gained significant attention due to their remarkable atomic utilization efficiency,interactions between single atoms(SAs)and metal supports,and free-atom-like electronic structure of dopant elements.In this work,we observed the formation of SAs in pre-deposited metal particles by a two-step thermal evaporation technique,thereby establishing the first instance of discovering SAAs by thermal evaporation.The discovery of SAAs by thermal evaporation extends the range of SAAs preparation methods to include this traditional synthetic technique,which offers convenience,cost-efficiency,and universality.The formation mechanism of SAAs prepared using this technique was elucidated by density functional theory calculations.It was demonstrated that thermal evaporation can be utilized to prepare SAAs with multiple SAs,further highlighting its universal applicability.展开更多
Two-dimensional platinum diselenide (PtSe_(2)) has been explored for applications in visible and infrared photodetectors, owing to its tunable electrical and optoelectronic properties governed by layer-dependent bandg...Two-dimensional platinum diselenide (PtSe_(2)) has been explored for applications in visible and infrared photodetectors, owing to its tunable electrical and optoelectronic properties governed by layer-dependent bandgaps. Studies have explored both positive photoconductivity (PPC) and negative photoconductivity (NPC) behaviors in few-layer PtSe_(2) thin films, proposing mechanisms related to gas molecule adsorption. However, these proposed mechanisms, typically based on models with ideal limit structures, often lacked consistency with the structure and scale of polycrystalline thin films employed in actual experiments. Here, photodetectors utilizing monolayer PtSe_(2) ribbons were designed, demonstrating a significant NPC effect upon exposure to visible light in atmospheric conditions, with device resistance increasing to over threefold the initial state. Under vacuum conditions, the device demonstrated PPC characteristics. Density functional theory calculations indicated that oxygen molecules physically adsorbed at the edges of PtSe_(2) ribbons were integral. Laser irradiation prompted the detachment of oxygen molecules from the ribbon’s edges, leading to a decreased carrier concentration in channel conductivity. The abundant edge sites of the ribbons endowed the photodetectors with a pronounced NPC response. This study diverted from traditional multilayer PtSe_(2) films to explore monolayer PtSe_(2) ribbons. These ribbons, as limit structures, offered a more fundamental insight into the intrinsic photoconductivity properties of PtSe_(2). Photodetectors employing PtSe_(2) ribbons presented novel application prospects in low-power photodetection, gas detection, and additional fields.展开更多
Millimeter waves are electromagnetic waves with wavelengths of 1–10 mm,which have characteristics of high frequency and short wavelength.They have gradually and widely been used in engineering and medical fields.We h...Millimeter waves are electromagnetic waves with wavelengths of 1–10 mm,which have characteristics of high frequency and short wavelength.They have gradually and widely been used in engineering and medical fields.We have identified studies related to millimeter waves in the biomedical field and summarized the biological effects of millimeter waves and their current status in medical applications.Finally,the shortcomings of existing studies and future developments were analyzed and discussed,with the aim of providing a reference for further research and development of millimeter waves in the medical field.展开更多
In foggy traffic scenarios, existing object detection algorithms face challenges such as low detection accuracy, poor robustness, occlusion, missed detections, and false detections. To address this issue, a multi-scal...In foggy traffic scenarios, existing object detection algorithms face challenges such as low detection accuracy, poor robustness, occlusion, missed detections, and false detections. To address this issue, a multi-scale object detection algorithm based on an improved YOLOv8 has been proposed. Firstly, a lightweight attention mechanism, Triplet Attention, is introduced to enhance the algorithm’s ability to extract multi-dimensional and multi-scale features, thereby improving the receptive capability of the feature maps. Secondly, the Diverse Branch Block (DBB) is integrated into the CSP Bottleneck with two Convolutions (C2F) module to strengthen the fusion of semantic information across different layers. Thirdly, a new decoupled detection head is proposed by redesigning the original network head based on the Diverse Branch Block module to improve detection accuracy and reduce missed and false detections. Finally, the Minimum Point Distance based Intersection-over-Union (MPDIoU) is used to replace the original YOLOv8 Complete Intersection-over-Union (CIoU) to accelerate the network’s training convergence. Comparative experiments and dehazing pre-processing tests were conducted on the RTTS and VOC-Fog datasets. Compared to the baseline YOLOv8 model, the improved algorithm achieved mean Average Precision (mAP) improvements of 4.6% and 3.8%, respectively. After defogging pre-processing, the mAP increased by 5.3% and 4.4%, respectively. The experimental results demonstrate that the improved algorithm exhibits high practicality and effectiveness in foggy traffic scenarios.展开更多
Forest fires pose a serious threat to ecological balance, air quality, and the safety of both humans and wildlife. This paper presents an improved model based on You Only Look Once version 5 (YOLOv5), named YOLO Light...Forest fires pose a serious threat to ecological balance, air quality, and the safety of both humans and wildlife. This paper presents an improved model based on You Only Look Once version 5 (YOLOv5), named YOLO Lightweight Fire Detector (YOLO-LFD), to address the limitations of traditional sensor-based fire detection methods in terms of real-time performance and accuracy. The proposed model is designed to enhance inference speed while maintaining high detection accuracy on resource-constrained devices such as drones and embedded systems. Firstly, we introduce Depthwise Separable Convolutions (DSConv) to reduce the complexity of the feature extraction network. Secondly, we design and implement the Lightweight Faster Implementation of Cross Stage Partial (CSP) Bottleneck with 2 Convolutions (C2f-Light) and the CSP Structure with 3 Compact Inverted Blocks (C3CIB) modules to replace the traditional C3 modules. This optimization enhances deep feature extraction and semantic information processing, thereby significantly increasing inference speed. To enhance the detection capability for small fires, the model employs a Normalized Wasserstein Distance (NWD) loss function, which effectively reduces the missed detection rate and improves the accuracy of detecting small fire sources. Experimental results demonstrate that compared to the baseline YOLOv5s model, the YOLO-LFD model not only increases inference speed by 19.3% but also significantly improves the detection accuracy for small fire targets, with only a 1.6% reduction in overall mean average precision (mAP)@0.5. Through these innovative improvements to YOLOv5s, the YOLO-LFD model achieves a balance between speed and accuracy, making it particularly suitable for real-time detection tasks on mobile and embedded devices.展开更多
Psoriasis is a common,chronic immune-mediated systemic disease that had no effective and durable treatment.Mesenchymal stem cells(MSCs)have immunomodulatory properties.Therefore,we performed a phase 1/2a,single-arm cl...Psoriasis is a common,chronic immune-mediated systemic disease that had no effective and durable treatment.Mesenchymal stem cells(MSCs)have immunomodulatory properties.Therefore,we performed a phase 1/2a,single-arm clinical trial to evaluate the safety and efficacy of human umbilical cord-derived MSCs(UMSCs)in the treatment of psoriasis and to preliminarily explore the possible mechanisms.Seventeen patients with psoriasis were enrolled and received UMsC infusions.Adverse events,laboratory parameters,PASl,and PGA were analyzed.We did not observe obvious side effects during the treatment and 6-month follow-up.A total of 47.1%(8/17)of the psoriasis patients had at least 40%improvement in the PASl score,and 17.6%(3/17)had no sign of disease or minimal disease based on the PGA score.And the efficiency was 25%(2/8)for males and 66.7%(6/9)for females.After UMSC transplantation(UMSCT),the frequencies of Tregs and CD4^(+)memory T cells were significantly increased,and the frequencies of T helper(Th)17 and CD4^(+)naive T cells were significantly decreased in peripheral blood(PB)of psoriasis patients.And all responders showed significant increases in Tregs and CD4^(+)memory T cells,and significant decreases in Th17 cells and serum IL-17 level after UMsCT.And baseline level of Tregs in responders were significantly lower than those in nonresponders.In conclusion,allogeneic UMSCT is safe and partially effective in psoriasis patients,and level of Tregs may be used as a potent biomarker to predict the clinical efficacy of UMSCT.Trial registration Clinical Trials NCT03765957.展开更多
Objective： To observe the clinical efficacy of surrounding electroacupuncture needling for breast mass after acute mastitis.Methods： Thirty patients with breast mass after acute mastitis who conformed to the inclusi...Objective： To observe the clinical efficacy of surrounding electroacupuncture needling for breast mass after acute mastitis.Methods： Thirty patients with breast mass after acute mastitis who conformed to the inclusion criteria were given surrounding electroacupuncture needling. Acupoint selection： 4-8 needles were needled around the mass and at Zusanli（足三里ST 36）,Sanyinjiao（三阴交SP 6）,Fengl6 ng（丰隆 ST 40） and Rugen（乳根 ST 18）. Electroacupuncture was performed at ST 36, SP 6 and ST 40. The above treatment was once a day. Treatment for 7 times was considered as 1 course of treatment, and 3 weeks were free from treatment between courses. Color ultrasound in breast was used to examine the breast mass before the next course of treatment, treatment can be terminated if the mass disappeared, otherwise, treatment should be continued. Three courses at most were needed.Results： After 1-3 courses of treatment, 16 patients were cured, accounting for 53.3%（16/30）; markedly effective： 8 cases, accounting for 26.7%（8/30）; effective： 4 cases, accounting for 13.3%（4/30）; ineffective：2 cases, accounting for 6.7%（2/30）.Conclusion： Surrounding electroacupuncture needling for breast mass after acute mastitis was effective clinically.展开更多
基金supported by the Major Science and TechnologyTechnol-ogy Projects in Gansu Province(No.22ZD6FA021-5)Industrial Support Project of Gansu Province(Nos.2023CYZC-19 and 2021CYZC-22)+1 种基金Science and Technol-ogy Project of Gansu Province(Nos.23YFFA0074,22JR5RA137,and 22JR5RA151)Central Leading Local Science and Technology Development Fund Projects(No.23ZYQA293).
文摘This study proposes a batch rapid quantitative analysis method for multiple elements by combining the advantages of standard curve(SC)and calibration-free laser-induced breakdown spectroscopy(CF-LIBS)technology to achieve synchronous,rapid,and accurate measurement of elements in a large number of samples,namely,SC-assisted CF-LIBS.Al alloy standard samples,divided into calibration and test samples,were applied to validate the proposed method.SC was built based on the characteristic line of Pb and Cr in the calibration sample,and the contents of Pb and Cr in the test sample were calculated with relative errors of 6%and 4%,respectively.SC built using Cr with multiple characteristic lines yielded better calculation results.The relative contents of ten elements in the test sample were calculated using CF-LIBS.Subsequently,the SC-assisted CF-LIBS was executed,with the majority of the calculation relative errors falling within the range of 2%-5%.Finally,the Al and Na contents of the Al alloy were predicted.The results demonstrate that it effectively enables the rapid and accurate quantitative analysis of multiple elements after a single-element SC analysis of the tested samples.Furthermore,this quantitative analysis method was successfully applied to soil and Astragalus samples,realizing an accurate calculation of the contents of multiple elements.Thus,it is important to advance the LIBS quantitative analysis and its related applications.
基金supported by the National Natural Science Foundation of China(609250056110216961501505)
文摘A novel adaptive detector for airborne radar space-time adaptive detection （STAD） in partially homogeneous environments is proposed. The novel detector combines the numerically stable Krylov subspace technique and diagonal loading technique, and it uses the framework of the adaptive coherence estimator （ACE）. It can effectively detect a target with low sample support. Compared with its natural competitors, the novel detector has higher proba- bility of detection （PD）, especially when the number of the training data is low. Moreover, it is shown to be practically constant false alarm rate （CFAR）.
基金supported by Research on Precision Nutrition and Health Food,Department of Science and Technology of Henan Province(CXJD2021006)。
文摘Two immunomodulatory polysaccharides(Vp2a-Ⅱ and Vp3) were isolated and identified from Apocynum venetum L. flowers, and their innate immune-stimulating functions and working mechanisms were evaluated in RAW264.7 cells. Both the level of released nitric oxide(NO) and expression of inducible nitric oxide synthase(iNOS) m RNA were significantly enhanced in the RAW264.7 macrophages cells treated by Vp2a-Ⅱ and Vp3. Vp2a-Ⅱ(100–800 μg/m L) and Vp3(400 μg/mL) could significantly increase the phagocytic activity of RAW264.7 cells and the secretion and m RNA expression of TNF-α and IL-6 in a concentrationdependent manner through affecting mitogen-activated protein kinase(MAPK) activity and nuclear factor κB(NF-κB) nuclear translocation. Vp2a-Ⅱ might activate the MAPK signaling pathways and induce the nuclear translocation of NF-κB p65, whilst Vp3 likely activated the NF-κB and MAPK signaling pathways without influencing the p38 MAPK route.
基金This work is supported by the National Key Research and Development Program of China(2020YFA0710902)Sichuan Science and Technology Program(2021YFG0214,2019YJ0227)+1 种基金Fundamental Research Funds for the Central Universities(2682021ZTPY124)State Key Laboratory of Traction Power(2019TPL_T02).
文摘The aerodynamic noise of high-speed trains passing through a tunnel has gradually become an important issue.Numerical approaches for predicting the aerodynamic noise sources of high-speed trains running in tunnels are the key to alleviating aerodynamic noise issues.In this paper,two typical numerical methods are used to calculate the aerodynamic noise of high-speed trains.These are the static method combined with non-reflective boundary conditions and the dynamic mesh method combined with adaptive mesh.The fluctuating pressure,flow field and aerodynamic noise source are numerically simulated using the abovemethods.The results showthat the fluctuating pressure,flow field structure and noise source characteristics obtained using different methods,are basically consistent.Compared to the dynamic mesh method,the pressure,vortex size and noise source radiation intensity,obtained by the static method,are larger.The differences are in the tail car and its wake.The two calculation methods show that the spectral characteristics of the surface noise source are consistent.The maximum difference in the sound pressure level is 1.9 dBA.The static method is more efficient and more suitable for engineering applications.
基金supported by National Natural Science Foundation of China(31900292)Science and Technology Development Program of Henan Province(202102110149,192102110112,and 182102410083)Science and Technology Project of Kaifeng(1908005,and 1803010).
文摘Compounds with regulating glucose metabolism and improving insulin resistance(IR)activity are abundant in nature and can be obtained from several sources.They have high potential to be used to treat diabetes mellitus.These compounds isolated from natural plants can be classified seven categories:terpenoids,alkaloids,quinones,flavonoids,phenols,phenyl propanoids,steroids,and other types of compounds.They exert biological effects by different ways and mechanisms.This review illustrated the potential natural products as a rich resource in regulation of glucose metabolism and IR,as well as their mechanisms.
基金supported by the National Natural Science Foundation of China(Grant No.62101275 and 62101274).
文摘With the rapid development of technology,processing the explosive growth of meteorological data on traditional standalone computing has become increasingly time-consuming,which cannot meet the demands of scientific research and business.Therefore,this paper proposes the implementation of the parallel Clustering Large Application based upon RANdomized Search(CLARANS)clustering algorithm on the Spark cloud computing platformto cluster China’s climate regions usingmeteorological data from1988 to 2018.The aim is to address the challenge of applying clustering algorithms to large datasets.In this paper,the morphological similarity distance is adopted as the similarity measurement standard instead of Euclidean distance,which improves clustering accuracy.Furthermore,the issue of local optima caused by an improper selection of initial clustering centers is addressed by utilizing the max-distance criterion.Compared to the k-means clustering algorithm already implemented in the Spark platform,the proposed algorithm has strong robustness,can reduce the interference of outliers in the dataset on clustering results,and has higher parallel performance than the frequently used serial algorithms,thus improving the efficiency of big data analysis.This experiment compares the clustered centroid data with the annual average meteorological data of representative cities in the five typical meteorological regions that exist in China,and the results show that the clustering results are in good agreement with the meteorological data obtained from the National Meteorological Science Data Center.This algorithm has a positive effect on the clustering analysis of massive meteorological data and deserves attention in scientific research activities.
基金Startup Foundation for Introducing Talent of NUISTNational Natural Science Foundation of China,Grant/Award Number:62006124+1 种基金Nature Science Foundation of Jiangsu Province,Grant/Award Number:BK20200811Natural Science Foundation of the Jiangsu Higher Edu-cation Institutions of China,Grant/Award Number:20KJB520006。
文摘The closed-loop wireless power transfer(WPT)system can realize constant voltage output in the presence of perturbation.However,the parameter design of the controller is a difficult problem.The traditional trial-and-error method is time-consuming and difficult to find optimal parameters.A parameter optimization strategy of control systems for uncertain WPT systems using the modified genetic algorithm(MGA)is proposed.Firstly,because the system has different characteristics at different periods,the simulation process is divided into three stages.The first one is the start-up stage,in which we mainly consider the overshoot and the rate of the voltage rise.The second one is the tracking stage,in which the tracking time and switching loss are mainly considered.The third one is the stabilisation stage,in which the steady-state error and switching loss are mainly considered.Secondly,three cost functions are designed according to the characteristics of the three stages,and then the optimal controller parameters of each stage are obtained by using MGA.Finally,the effectiveness of the proposed method is verified by simulation.The optimization results show that compared with the previous parameter optimization method,the optimal controller parameters obtained by the proposed method make the WPT system achieve better performance.
基金from National Natural Science Foundation of China(Grant Nos:41773075,41575137,31370494,31170421).
文摘Background:The nitrogen isotope natural abundance(δ^(15)N)provides integrated information on ecosystem N dynamics,and carbon isotope natural abundance(δ^(13)C)has been used to infer how water-using processes of plants change in terrestrial ecosystems.However,howδ^(13)C andδ^(15)N abundances in plant life and soils respond to N addition and water availability change is still unclear.Thus,δ^(13)C andδ^(15)N abundances in plant life and soils were used to investigate the effects of long-time(10 years)N addition(+50 kg N·ha^(−1)·yr^(−1)and precipitation reduction(−30%of throughfall)in forest C and N cycling traits in a temperate forest in northern China.Results:We analyzed theδ^(13)C andδ^(15)N values of dominant plant foliage,litterfall,fungal sporophores,roots,and soils in the study.The results showed thatδ^(15)N values of foliage,litterfall,and surface soil layer’s(0–10 cm)total N were significantly increased by N addition,whileδ^(15)N values of fine roots and coarse roots were considerably decreased.Nitrogen addition also significantly increased theδ^(13)C value of fine roots and total N concentration of the surface soil layer compared with the control.The C concentration,δ^(13)C,andδ^(15)N values of foliage andδ^(15)N values of fine roots were significantly increased by precipitation reduction,while N concentration of foliage and litterfall significantly decreased.The combined effects of N addition and precipitation reduction significantly increased theδ^(13)C andδ^(15)N values of foliage as well as theδ^(15)N values of fine roots andδ^(13)C values of litterfall.Furthermore,foliarδ^(15)N values were significantly correlated with foliageδ^(13)C values,surface soilδ^(15)N values,surface soil C concentration,and N concentrations.Nitrogen concentrations andδ^(13)C values of foliage were significantly correlated withδ^(15)N values and N concentrations of fine roots.Conclusions:This indicates that plants increasingly take up the heavier 15N under N addition and the heavier 13C and 15N under precipitation reduction,suggesting that N addition and precipitation reduction may lead to more open forest ecosystem C and N cycling and affect plant nutrient acquisition strategies.
文摘Recently,we read with interest the findings of Zhang et al.1 of the long-term bone consequences in severe acute respiratory syndrome(SARS)patients.Their conclusion suggested that pulmonary damage and femoral head necrosis could be halted and reversed in SARS patients during the 15-year follow-up.These results have very important implications for the treatment and health utility evaluation of coronavirus disease 2019(COVID-19).However,they did not explore the reasons for the reversal of femoral head necrosis after large doses of steroid pulse therapy,which may affect our understanding with regard to the treatment of COVID-19 patients.
文摘Background: There is very limited data available about the epidemiology trial on chronic diseases comprehensive intervention. The aim of this study was to assess the effect of comprehensive intervention on chronic diseases in Baoji and provide basis for the improvement of chronic diseases intervention measures. Methods: Using four stages stratified random sampling method, comprehensive intervention measures were implemented on intervention group (575 individuals) respectively aimed at three crowds of whole population, high risk population and chronic diseases patients. The control group (782 individuals) did not receive special treatment. Two groups were evaluated effect after one year observation. Results: The chronic diseases prevalence rate of whole population in intervention group was lower than that in control group (P < 0.05), the blood pressure level and smoking proportion of high risk population in intervention group were lower than in control group (P < 0.05), and the blood pressure, blood glucose control rate of chronic diseases patients in intervention group were higher than in control group (P < 0.05). Conclusion: Comprehensive intervention could prevent the rise of chronic diseases prevalence. The intervention is effective in reducing or halting risk factors of high risk population, particularly in controlling blood pressure, blood glucose of patients. We should establish government leading, department cooperation, social participation, longtime and classified comprehensive intervention mechanism of chronic diseases. We believe that whole population should control the risk factors, high risk population should early diagnosis and treatment, chronic diseases patients should normalized management, and it could be applied in other counties.
基金supported by the National Natural Science Foundation of China(No.52172046).
文摘Single-atom alloys(SAAs)have gained significant attention due to their remarkable atomic utilization efficiency,interactions between single atoms(SAs)and metal supports,and free-atom-like electronic structure of dopant elements.In this work,we observed the formation of SAs in pre-deposited metal particles by a two-step thermal evaporation technique,thereby establishing the first instance of discovering SAAs by thermal evaporation.The discovery of SAAs by thermal evaporation extends the range of SAAs preparation methods to include this traditional synthetic technique,which offers convenience,cost-efficiency,and universality.The formation mechanism of SAAs prepared using this technique was elucidated by density functional theory calculations.It was demonstrated that thermal evaporation can be utilized to prepare SAAs with multiple SAs,further highlighting its universal applicability.
基金supported by the National Natural Science Foundation of China(No.52172046).
文摘Two-dimensional platinum diselenide (PtSe_(2)) has been explored for applications in visible and infrared photodetectors, owing to its tunable electrical and optoelectronic properties governed by layer-dependent bandgaps. Studies have explored both positive photoconductivity (PPC) and negative photoconductivity (NPC) behaviors in few-layer PtSe_(2) thin films, proposing mechanisms related to gas molecule adsorption. However, these proposed mechanisms, typically based on models with ideal limit structures, often lacked consistency with the structure and scale of polycrystalline thin films employed in actual experiments. Here, photodetectors utilizing monolayer PtSe_(2) ribbons were designed, demonstrating a significant NPC effect upon exposure to visible light in atmospheric conditions, with device resistance increasing to over threefold the initial state. Under vacuum conditions, the device demonstrated PPC characteristics. Density functional theory calculations indicated that oxygen molecules physically adsorbed at the edges of PtSe_(2) ribbons were integral. Laser irradiation prompted the detachment of oxygen molecules from the ribbon’s edges, leading to a decreased carrier concentration in channel conductivity. The abundant edge sites of the ribbons endowed the photodetectors with a pronounced NPC response. This study diverted from traditional multilayer PtSe_(2) films to explore monolayer PtSe_(2) ribbons. These ribbons, as limit structures, offered a more fundamental insight into the intrinsic photoconductivity properties of PtSe_(2). Photodetectors employing PtSe_(2) ribbons presented novel application prospects in low-power photodetection, gas detection, and additional fields.
基金the National Natural Science Foundation of China(Grant No.81974355)Establishment of the National Intelligent Medical Clinical Research Center(Grant No.2020021105012440)Hubei Province’s New Generation of Artificial Intelligence Key Research and Development Projects(Grant No.2021BEA161).
文摘Millimeter waves are electromagnetic waves with wavelengths of 1–10 mm,which have characteristics of high frequency and short wavelength.They have gradually and widely been used in engineering and medical fields.We have identified studies related to millimeter waves in the biomedical field and summarized the biological effects of millimeter waves and their current status in medical applications.Finally,the shortcomings of existing studies and future developments were analyzed and discussed,with the aim of providing a reference for further research and development of millimeter waves in the medical field.
基金supported by the National Natural Science Foundation of China(Grant Nos.62101275 and 62101274).
文摘In foggy traffic scenarios, existing object detection algorithms face challenges such as low detection accuracy, poor robustness, occlusion, missed detections, and false detections. To address this issue, a multi-scale object detection algorithm based on an improved YOLOv8 has been proposed. Firstly, a lightweight attention mechanism, Triplet Attention, is introduced to enhance the algorithm’s ability to extract multi-dimensional and multi-scale features, thereby improving the receptive capability of the feature maps. Secondly, the Diverse Branch Block (DBB) is integrated into the CSP Bottleneck with two Convolutions (C2F) module to strengthen the fusion of semantic information across different layers. Thirdly, a new decoupled detection head is proposed by redesigning the original network head based on the Diverse Branch Block module to improve detection accuracy and reduce missed and false detections. Finally, the Minimum Point Distance based Intersection-over-Union (MPDIoU) is used to replace the original YOLOv8 Complete Intersection-over-Union (CIoU) to accelerate the network’s training convergence. Comparative experiments and dehazing pre-processing tests were conducted on the RTTS and VOC-Fog datasets. Compared to the baseline YOLOv8 model, the improved algorithm achieved mean Average Precision (mAP) improvements of 4.6% and 3.8%, respectively. After defogging pre-processing, the mAP increased by 5.3% and 4.4%, respectively. The experimental results demonstrate that the improved algorithm exhibits high practicality and effectiveness in foggy traffic scenarios.
基金supported by the National Natural Science Foundation of China(Grant Nos.62101275 and 62101274).
文摘Forest fires pose a serious threat to ecological balance, air quality, and the safety of both humans and wildlife. This paper presents an improved model based on You Only Look Once version 5 (YOLOv5), named YOLO Lightweight Fire Detector (YOLO-LFD), to address the limitations of traditional sensor-based fire detection methods in terms of real-time performance and accuracy. The proposed model is designed to enhance inference speed while maintaining high detection accuracy on resource-constrained devices such as drones and embedded systems. Firstly, we introduce Depthwise Separable Convolutions (DSConv) to reduce the complexity of the feature extraction network. Secondly, we design and implement the Lightweight Faster Implementation of Cross Stage Partial (CSP) Bottleneck with 2 Convolutions (C2f-Light) and the CSP Structure with 3 Compact Inverted Blocks (C3CIB) modules to replace the traditional C3 modules. This optimization enhances deep feature extraction and semantic information processing, thereby significantly increasing inference speed. To enhance the detection capability for small fires, the model employs a Normalized Wasserstein Distance (NWD) loss function, which effectively reduces the missed detection rate and improves the accuracy of detecting small fire sources. Experimental results demonstrate that compared to the baseline YOLOv5s model, the YOLO-LFD model not only increases inference speed by 19.3% but also significantly improves the detection accuracy for small fire targets, with only a 1.6% reduction in overall mean average precision (mAP)@0.5. Through these innovative improvements to YOLOv5s, the YOLO-LFD model achieves a balance between speed and accuracy, making it particularly suitable for real-time detection tasks on mobile and embedded devices.
基金This study was sponsored by The National Key Research and Development Project of China(2020YFA0112900,2018YFC0117004)The National Natural Science Foundation of China(82073447,81573049)+1 种基金The Key Research and Development Program of Hunan Province(2018SK2082)The Research and Development Project of Hunan Guangxiu High-tech Life Technology Co,Ltd(2019RES08).
文摘Psoriasis is a common,chronic immune-mediated systemic disease that had no effective and durable treatment.Mesenchymal stem cells(MSCs)have immunomodulatory properties.Therefore,we performed a phase 1/2a,single-arm clinical trial to evaluate the safety and efficacy of human umbilical cord-derived MSCs(UMSCs)in the treatment of psoriasis and to preliminarily explore the possible mechanisms.Seventeen patients with psoriasis were enrolled and received UMsC infusions.Adverse events,laboratory parameters,PASl,and PGA were analyzed.We did not observe obvious side effects during the treatment and 6-month follow-up.A total of 47.1%(8/17)of the psoriasis patients had at least 40%improvement in the PASl score,and 17.6%(3/17)had no sign of disease or minimal disease based on the PGA score.And the efficiency was 25%(2/8)for males and 66.7%(6/9)for females.After UMSC transplantation(UMSCT),the frequencies of Tregs and CD4^(+)memory T cells were significantly increased,and the frequencies of T helper(Th)17 and CD4^(+)naive T cells were significantly decreased in peripheral blood(PB)of psoriasis patients.And all responders showed significant increases in Tregs and CD4^(+)memory T cells,and significant decreases in Th17 cells and serum IL-17 level after UMsCT.And baseline level of Tregs in responders were significantly lower than those in nonresponders.In conclusion,allogeneic UMSCT is safe and partially effective in psoriasis patients,and level of Tregs may be used as a potent biomarker to predict the clinical efficacy of UMSCT.Trial registration Clinical Trials NCT03765957.
文摘Objective： To observe the clinical efficacy of surrounding electroacupuncture needling for breast mass after acute mastitis.Methods： Thirty patients with breast mass after acute mastitis who conformed to the inclusion criteria were given surrounding electroacupuncture needling. Acupoint selection： 4-8 needles were needled around the mass and at Zusanli（足三里ST 36）,Sanyinjiao（三阴交SP 6）,Fengl6 ng（丰隆 ST 40） and Rugen（乳根 ST 18）. Electroacupuncture was performed at ST 36, SP 6 and ST 40. The above treatment was once a day. Treatment for 7 times was considered as 1 course of treatment, and 3 weeks were free from treatment between courses. Color ultrasound in breast was used to examine the breast mass before the next course of treatment, treatment can be terminated if the mass disappeared, otherwise, treatment should be continued. Three courses at most were needed.Results： After 1-3 courses of treatment, 16 patients were cured, accounting for 53.3%（16/30）; markedly effective： 8 cases, accounting for 26.7%（8/30）; effective： 4 cases, accounting for 13.3%（4/30）; ineffective：2 cases, accounting for 6.7%（2/30）.Conclusion： Surrounding electroacupuncture needling for breast mass after acute mastitis was effective clinically.
