This study was carried out at Gezira area in Central Sudan that lies between longitude 32° and 32° 50＇ and latitude 14° and 14°15＇. It dealt with the history of the sand, its source and rate of m...This study was carried out at Gezira area in Central Sudan that lies between longitude 32° and 32° 50＇ and latitude 14° and 14°15＇. It dealt with the history of the sand, its source and rate of movement towards Gezira scheme and monitored the trend of blowing sand over 10 years. To find out the origin of drifting sand, sand samples were collected from the sandy area west to the White Nile and from the study area. Heavy minerals analysis was carried out on these samples and its mineral assemblage was matched with the mineral of both sand at western bank of the White Nile and the Blue Nile. To picture the trend of moving sand, Multispectral Scanning System （MSS, 1975）, and Thematic Map （TM, 1985） were used to delineate the sandy areas and their trend with time. The rate of the blowing sand was quantified using Bottemane sand catcher. The heavy mineral results showed that the mineral of the drifting sand in the study area are quite similar to the sand of sand dune west to the White Nile indicating the same origin. The sand was transported by southern and southwestern winds through a corridor across the White Nile to its eastern bank, where the most likely water transported sediment was reworked by wind and transported further to the northeast. Between 1972 and 1985, the sand invaded the area at an average rate of about 30 km2 per year and map of 1985 demonstrated a corridor across the White Nile for sand movement. The area was subject to 7 days sand storm with an average of 35 kg/m.d and in summer time, the average amount of moving sand was about 28 kg/m.d. These results demonstrated the future hazard of drifting sand and its impact, which has to be tackled immediately to protect Gezira scheme.展开更多
In the smoothed particle hydrodynamics (SPH) method, a meshless interpolation scheme is needed for the unknown function in order to discretize the governing equation.A particle approximation method has so far been use...In the smoothed particle hydrodynamics (SPH) method, a meshless interpolation scheme is needed for the unknown function in order to discretize the governing equation.A particle approximation method has so far been used for this purpose.Traditional particle interpolation (TPI) is simple and easy to do, but its low accuracy has become an obstacle to its wider application.This can be seen in the cases of particle disorder arrangements and derivative calculations.There are many different methods to improve accuracy, with the moving least square (MLS) method one of the most important meshless interpolation methods.Unfortunately, it requires complex matrix computing and so is quite time-consuming.The authors developed a simpler scheme, called higher-order particle interpolation (HPI).This scheme can get more accurate derivatives than the MLS method, and its function value and derivatives can be obtained simultaneously.Although this scheme was developed for the SPH method, it has been found useful for other meshless methods.展开更多
Objective To investigate lateralization and Coherence analysis of blood perfusion in bilateral Neiguan （内关 PC 6） in different ages. Methods Healthy volunteers （n=30） were placed in a temperature-controlled room ...Objective To investigate lateralization and Coherence analysis of blood perfusion in bilateral Neiguan （内关 PC 6） in different ages. Methods Healthy volunteers （n=30） were placed in a temperature-controlled room as a resting state for 40 min. Then the blood perfusion of bilateral PC 6 were carried out using PeriFlux System 5000 for 25 minutes. Mean blood flux of every 5 minutes was calculated. Then the participants were divided into groups of young （n=18） and the old （n=12） as the boundary of 40 years, the asymmetry index and coherence value of bilateral PC 6 were analyzed in different group. Results The mean blood flow of the right PC 6 was significantly higher than the left PC 6 in three different epochs, the mean blood flow of right PC 6 vs left PC 6 is 9.74±3.36 vs 6.73±2.22 （t=5.9, P〈0.001）, 9.83±3.63 vs 6.99±2.37 （t=5.11, P〈0.001） and 9.69±3.40 vs 6.77±2.32 （t=5.99, P〈0.001）, respectively. Although the asymmetry index is higher in old group than in young group, there is no statistically significant age-related differences. Coherence analysis suggest that there is significant difference in frequency value corresponding to peak crest between young and old group. Conclusion The blood perfusion in right PC 6 is higher than left PC 6. Coherence analysis of laser Doppler flowmetry signals in bilateral PC 6 might provide a potential non-invasive method to assess microcirculatory changes in different ages.展开更多
Detrimental defects on perovskite grain boundaries(GBs)are critical factors that lead to non-radiative recombination and hysteresis.In this work,triazine-graphdiyne(Tra-GD),a nitrogen-rich two-dimensional(2 D)material...Detrimental defects on perovskite grain boundaries(GBs)are critical factors that lead to non-radiative recombination and hysteresis.In this work,triazine-graphdiyne(Tra-GD),a nitrogen-rich two-dimensional(2 D)material,was incorporated into the active layer of perovskite to modify the GBs.Tra-GD was found to distribute evenly over the bulk of the perovskite and has a strong interaction with the Pb^2+ exposed at GBs,which enables it to effectively passivate GB defects and prevent ion migration.The results of Kelvin probe force microscopy and photoluminescence studies proved that the highly conjugated Tra-GD located at GBs could promote charge extraction and transport.Benefiting from defect passivation and more efficient carrier transport,the Tra-GD based device showed less non-radiative recombination loss.Consequently,the resultant device presented negligible hysteresis and yielded a high power conversion efficiency(PCE)of 20.33%in the MAPbI3-based perovskite solar cell.This approach was extended to the FAPbI3 system with a PCE of 21.16%.Our Tra-GD passivation strategy provides a useful approach to effectively improving the device performance and addressing hysteresis issues.展开更多
We present a systematic light-cone QCD sum rule study of the exclusive rare radiative decay Ab → Aγ and rare semileptonic decay Ab→ Al＋ l- within the framework of the standard model. Although some light-cone sum r...We present a systematic light-cone QCD sum rule study of the exclusive rare radiative decay Ab → Aγ and rare semileptonic decay Ab→ Al＋ l- within the framework of the standard model. Although some light-cone sum rule （LCSR） studies on these rare processes can be found in different literatures, it is necessary to reanalyze them systematically for the reason that either the baryonic distribution amplitudes are improved or different interpolating currents for the Ab baryon may lead to quite different results. In addition, the rare process Ab →Aγ has not yet been analyzed by LCSR with the Ioffe-type current. Taking all these reasons into account, we perform LCSR calculations of both the processes with two types of interpolating currents. Our calculations show that the choice of the interpolating current for the Ab baryon can affect the predictions significantly, especially for the rare radiative decay process.展开更多
文摘This study was carried out at Gezira area in Central Sudan that lies between longitude 32° and 32° 50＇ and latitude 14° and 14°15＇. It dealt with the history of the sand, its source and rate of movement towards Gezira scheme and monitored the trend of blowing sand over 10 years. To find out the origin of drifting sand, sand samples were collected from the sandy area west to the White Nile and from the study area. Heavy minerals analysis was carried out on these samples and its mineral assemblage was matched with the mineral of both sand at western bank of the White Nile and the Blue Nile. To picture the trend of moving sand, Multispectral Scanning System （MSS, 1975）, and Thematic Map （TM, 1985） were used to delineate the sandy areas and their trend with time. The rate of the blowing sand was quantified using Bottemane sand catcher. The heavy mineral results showed that the mineral of the drifting sand in the study area are quite similar to the sand of sand dune west to the White Nile indicating the same origin. The sand was transported by southern and southwestern winds through a corridor across the White Nile to its eastern bank, where the most likely water transported sediment was reworked by wind and transported further to the northeast. Between 1972 and 1985, the sand invaded the area at an average rate of about 30 km2 per year and map of 1985 demonstrated a corridor across the White Nile for sand movement. The area was subject to 7 days sand storm with an average of 35 kg/m.d and in summer time, the average amount of moving sand was about 28 kg/m.d. These results demonstrated the future hazard of drifting sand and its impact, which has to be tackled immediately to protect Gezira scheme.
基金Supported by the National Natural Science Foundation of China under Grant No.10572041,50779008Doctoral Fund of Ministry of Education of China under Grant No.20060217009
文摘In the smoothed particle hydrodynamics (SPH) method, a meshless interpolation scheme is needed for the unknown function in order to discretize the governing equation.A particle approximation method has so far been used for this purpose.Traditional particle interpolation (TPI) is simple and easy to do, but its low accuracy has become an obstacle to its wider application.This can be seen in the cases of particle disorder arrangements and derivative calculations.There are many different methods to improve accuracy, with the moving least square (MLS) method one of the most important meshless interpolation methods.Unfortunately, it requires complex matrix computing and so is quite time-consuming.The authors developed a simpler scheme, called higher-order particle interpolation (HPI).This scheme can get more accurate derivatives than the MLS method, and its function value and derivatives can be obtained simultaneously.Although this scheme was developed for the SPH method, it has been found useful for other meshless methods.
基金Supported by the Fundamental Research Funds for the Central Public Welfare Research Institutes:ZZ070806National Natural Science Foundation of China:81001553National Basic Research Program of China:2015CB554502
文摘Objective To investigate lateralization and Coherence analysis of blood perfusion in bilateral Neiguan （内关 PC 6） in different ages. Methods Healthy volunteers （n=30） were placed in a temperature-controlled room as a resting state for 40 min. Then the blood perfusion of bilateral PC 6 were carried out using PeriFlux System 5000 for 25 minutes. Mean blood flux of every 5 minutes was calculated. Then the participants were divided into groups of young （n=18） and the old （n=12） as the boundary of 40 years, the asymmetry index and coherence value of bilateral PC 6 were analyzed in different group. Results The mean blood flow of the right PC 6 was significantly higher than the left PC 6 in three different epochs, the mean blood flow of right PC 6 vs left PC 6 is 9.74±3.36 vs 6.73±2.22 （t=5.9, P〈0.001）, 9.83±3.63 vs 6.99±2.37 （t=5.11, P〈0.001） and 9.69±3.40 vs 6.77±2.32 （t=5.99, P〈0.001）, respectively. Although the asymmetry index is higher in old group than in young group, there is no statistically significant age-related differences. Coherence analysis suggest that there is significant difference in frequency value corresponding to peak crest between young and old group. Conclusion The blood perfusion in right PC 6 is higher than left PC 6. Coherence analysis of laser Doppler flowmetry signals in bilateral PC 6 might provide a potential non-invasive method to assess microcirculatory changes in different ages.
基金supported by the Natural Science Foundation of China(51672288 and 21975273)Taishan Scholars Program of Shandong Province+2 种基金Youth Innovation Promotion Association of Chinese Academy of Sciences,Dalian National Laboratory for Clean Energy(DICP QIBEBT UN201705)Scientific Research Cooperation Foundation of Qingdao Institute of Bioenergy and Bioprocess Technology,Chinese Academy of Sciencesthe support of Qingdao Postdoctoral Application Research Project(2018183 and 2018186)。
文摘Detrimental defects on perovskite grain boundaries(GBs)are critical factors that lead to non-radiative recombination and hysteresis.In this work,triazine-graphdiyne(Tra-GD),a nitrogen-rich two-dimensional(2 D)material,was incorporated into the active layer of perovskite to modify the GBs.Tra-GD was found to distribute evenly over the bulk of the perovskite and has a strong interaction with the Pb^2+ exposed at GBs,which enables it to effectively passivate GB defects and prevent ion migration.The results of Kelvin probe force microscopy and photoluminescence studies proved that the highly conjugated Tra-GD located at GBs could promote charge extraction and transport.Benefiting from defect passivation and more efficient carrier transport,the Tra-GD based device showed less non-radiative recombination loss.Consequently,the resultant device presented negligible hysteresis and yielded a high power conversion efficiency(PCE)of 20.33%in the MAPbI3-based perovskite solar cell.This approach was extended to the FAPbI3 system with a PCE of 21.16%.Our Tra-GD passivation strategy provides a useful approach to effectively improving the device performance and addressing hysteresis issues.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 11205242, 10975184, 11105222, and 11105223
文摘We present a systematic light-cone QCD sum rule study of the exclusive rare radiative decay Ab → Aγ and rare semileptonic decay Ab→ Al＋ l- within the framework of the standard model. Although some light-cone sum rule （LCSR） studies on these rare processes can be found in different literatures, it is necessary to reanalyze them systematically for the reason that either the baryonic distribution amplitudes are improved or different interpolating currents for the Ab baryon may lead to quite different results. In addition, the rare process Ab →Aγ has not yet been analyzed by LCSR with the Ioffe-type current. Taking all these reasons into account, we perform LCSR calculations of both the processes with two types of interpolating currents. Our calculations show that the choice of the interpolating current for the Ab baryon can affect the predictions significantly, especially for the rare radiative decay process.
