To reduce the cost and increase the efficiency of plant genetic marker fingerprinting for variety discrimination,it is desirable to identify the optimal marker combinations.We describe a marker combination screening m...To reduce the cost and increase the efficiency of plant genetic marker fingerprinting for variety discrimination,it is desirable to identify the optimal marker combinations.We describe a marker combination screening model based on the genetic algorithm(GA)and implemented in a software tool,Loci Scan.Ratio-based variety discrimination power provided the largest optimization space among multiple fitness functions.Among GA parameters,an increase in population size and generation number enlarged optimization depth but also calculation workload.Exhaustive algorithm afforded the same optimization depth as GA but vastly increased calculation time.In comparison with two other software tools,Loci Scan accommodated missing data,reduced calculation time,and offered more fitness functions.In large datasets,the sample size of training data exerted the strongest influence on calculation time,whereas the marker size of training data showed no effect,and target marker number had limited effect on analysis speed.展开更多
A considerable amount of Hg is retained in flue gas desulfurization（FGD） gypsum from Wet Flue Gas Desulfurization（WFGD） systems. For this reason, it is important to determine the species of Hg in FGD gypsum not on...A considerable amount of Hg is retained in flue gas desulfurization（FGD） gypsum from Wet Flue Gas Desulfurization（WFGD） systems. For this reason, it is important to determine the species of Hg in FGD gypsum not only to understand the mechanism of Hg removal by WFGD systems but also to determine the final fate of Hg when FGD gypsum is disposed. In this study, Temperature Programmed Decomposition（TPD） and Sequential Chemical Extraction（SCE） were applied to FGD gypsum to identify the Hg species in it. The FGD gypsum samples were collected from seven coal-fired power plants in China, with Hg concentrations ranging from 0.19 to 3.27 μg/g. A series of pure Hg compounds were used as reference materials in TPD experiments and the results revealed that the decomposition temperatures of different Hg compounds increase in the order of Hg_2Cl_2〈 HgCl_2〈 black HgS 〈 Hg_2SO_4〈 red HgS 〈 HgO 〈 HgSO_4. The Hg compounds existing in FGD gypsums identified by TPD included HgCl_2, Hg_2Cl_2, Hg_2SO_4, black HgS and red HgS, of which mercury sulfides were the primary compounds. The results of SCE indicated that Hg was mainly distributed in the strongly complexed phase. The low Hg content in FGD gypsum increases the ambiguity of assigning extraction fractions to certain Hg species by SCE. The fact that the primary compounds in FGD gypsum are HgS phases leads the leaching of Hg in the natural environment to be quite low, but a considerable amount of Hg may be released during the industrial heating process.展开更多
Diverse heterotic groups have been developed in China over several decades,but their genomic divergences have not been systematically studied after improvement.In this study,we performed Maize6H-60K array of 5,822 mai...Diverse heterotic groups have been developed in China over several decades,but their genomic divergences have not been systematically studied after improvement.In this study,we performed Maize6H-60K array of 5,822 maize accessions and whole-genome re-sequencing of 150 inbred lines collected in China.Using multiple population structure analysis methods,we established a genetic boundary used to categorize heterotic groups and germplasm resources.We identified three chloroplast–cytoplasmic types that evolved during adaptation to diverse climatic environments in maize through phylogenetic and haplotype analyses.Comparative analyses revealed obvious genetic differences between heterotic groups and germplasm resources at both the chloroplast and nuclear genome levels,especially in the unique heterotic groups HG1 and HG2,which exhibited distinct regionality and genetic uniqueness.The divergent differentiation of heterotic groups from germplasm resources was driven by differential selection in specific genomic regions.Genome-wide selective sweep analysis identified core selected regions and candidate selected genes associated with traits between heterotic groups,highlighting that stress response-and plant defense-related genes were selected for environmental adaptation across a broad latitudinal range in China.Meanwhile,a genome-wide association study analysis provided evidence that core selected genes served as an important candidate gene pool with a potential role in genetic improvement.Gene exchanges among heterotic groups,which avoided the predominant heterotic patterns as much as possible,occurred to achieve population improvement during modern maize breeding.This study provides insights into the population differentiation and genetic characteristics of heterotic groups,which will facilitate the utilization of germplasm resources,the creation of novel maize germplasm,and the optimization of heterotic patterns during future maize breeding in China.展开更多
Aims:In this work,we evaluated the performance of three pitches positron emission tomography(PET)detectors for building a high-resolution small-animal PET imaging experimental platform.Methods:The evaluation of PET de...Aims:In this work,we evaluated the performance of three pitches positron emission tomography(PET)detectors for building a high-resolution small-animal PET imaging experimental platform.Methods:The evaluation of PET detectors includes twodimensional crystal identification,energy resolution,and crystal look-up table.The nuclear instrumentation module and PXI data acquisition(DAQ)system were both used to obtain flood images.The energy spectrum of the Na-22 source was measured.PET detectors of 2.0 and 1.6 mm pitches used in our present experiment were composed of lutetium yttrium oxyorthosilicate(LYSO)crystals directly coupled to position-sensitive photomultiplier tubes(PSPMTs).The 1.3-mm pitch detector comprises a LYSO crystal,a tapered light-guide,and a PSPMT.The crystal sizes of the detectors were a 10×10 array of 2.0×2.0×10 mm^(3) crystals,a 10×10 array of 1.6×1.6×10 mm^(3) crystals,and an 18×18 array of 1.3×1.3×10 mm^(3) crystals,respectively.Due to the lower sampling frequency of the DAQ system,a spline interpolation algorithm was introduced in the signal waveform to reconstruct the peak values.Results:The experimental results indicated that all three PET detector crystals could be clearly identified.A detailed analysis demonstrated that the key characteristic full width at half maximum(FWHM)values of the crystals profile could reach 0.46±0.03,0.32±0.03,and 0.21±0.02 mm,while the crystal average energy resolutions were 16.8%±1.76%,20.1%±2.24%,and 31.5%±3.76%,which correspond to pitches of 2.0-,1.6-,and 1.3-mm,respectively.Conclusions:The PET detector modules of LYSO crystal arrays could be potentially used in the small-animal PET imaging applications and are promising to achieve submillimeter PET images.展开更多
We proposed a novel Al Ga N/Ga N enhancement-mode（E-mode） high electron mobility transistor（HEMT） with a dual-gate structure and carried out the detailed numerical simulation of device operation using Silvaco Atla...We proposed a novel Al Ga N/Ga N enhancement-mode（E-mode） high electron mobility transistor（HEMT） with a dual-gate structure and carried out the detailed numerical simulation of device operation using Silvaco Atlas. The dual-gate device is based on a cascode connection of an E-mode and a D-mode gate. The simulation results show that electric field under the gate is decreased by more than 70% compared to that of the conventional E-mode MIS-HEMTs（from 2.83 MV/cm decreased to 0.83 MV/cm）. Thus, with the discussion of ionized trap density, the proposed dual-gate structure can highly improve electric field-related reliability, such as, threshold voltage stability. In addition, compared with HEMT with field plate structure, the proposed structure exhibits a simplified fabrication process and a more effective suppression of high electric field.展开更多
基金supported by the Scientific and Technological Innovation 2030 Major Project(2022ZD04019)the Science and Technology Innovation Capacity Building Project of BAAFS(KJCX20230303)+1 种基金Hainan Province Science and Technology Special Fund(ZDYF2023XDNY077)the Beijing Scholars Program(BSP041)。
文摘To reduce the cost and increase the efficiency of plant genetic marker fingerprinting for variety discrimination,it is desirable to identify the optimal marker combinations.We describe a marker combination screening model based on the genetic algorithm(GA)and implemented in a software tool,Loci Scan.Ratio-based variety discrimination power provided the largest optimization space among multiple fitness functions.Among GA parameters,an increase in population size and generation number enlarged optimization depth but also calculation workload.Exhaustive algorithm afforded the same optimization depth as GA but vastly increased calculation time.In comparison with two other software tools,Loci Scan accommodated missing data,reduced calculation time,and offered more fitness functions.In large datasets,the sample size of training data exerted the strongest influence on calculation time,whereas the marker size of training data showed no effect,and target marker number had limited effect on analysis speed.
基金supported by the National Natural Science Foundation of China (No. 51376109)
文摘A considerable amount of Hg is retained in flue gas desulfurization（FGD） gypsum from Wet Flue Gas Desulfurization（WFGD） systems. For this reason, it is important to determine the species of Hg in FGD gypsum not only to understand the mechanism of Hg removal by WFGD systems but also to determine the final fate of Hg when FGD gypsum is disposed. In this study, Temperature Programmed Decomposition（TPD） and Sequential Chemical Extraction（SCE） were applied to FGD gypsum to identify the Hg species in it. The FGD gypsum samples were collected from seven coal-fired power plants in China, with Hg concentrations ranging from 0.19 to 3.27 μg/g. A series of pure Hg compounds were used as reference materials in TPD experiments and the results revealed that the decomposition temperatures of different Hg compounds increase in the order of Hg_2Cl_2〈 HgCl_2〈 black HgS 〈 Hg_2SO_4〈 red HgS 〈 HgO 〈 HgSO_4. The Hg compounds existing in FGD gypsums identified by TPD included HgCl_2, Hg_2Cl_2, Hg_2SO_4, black HgS and red HgS, of which mercury sulfides were the primary compounds. The results of SCE indicated that Hg was mainly distributed in the strongly complexed phase. The low Hg content in FGD gypsum increases the ambiguity of assigning extraction fractions to certain Hg species by SCE. The fact that the primary compounds in FGD gypsum are HgS phases leads the leaching of Hg in the natural environment to be quite low, but a considerable amount of Hg may be released during the industrial heating process.
基金funded by the Biological Breeding-National Science and Technology Major Project(2022ZD04017)the Construction and Scientific and Technological Innovation Capacity of Beijing Academy of Agriculture and Forestry Sciences(No.KJCX20230301)National Innovation Center forDigital Seed Industry。
文摘Diverse heterotic groups have been developed in China over several decades,but their genomic divergences have not been systematically studied after improvement.In this study,we performed Maize6H-60K array of 5,822 maize accessions and whole-genome re-sequencing of 150 inbred lines collected in China.Using multiple population structure analysis methods,we established a genetic boundary used to categorize heterotic groups and germplasm resources.We identified three chloroplast–cytoplasmic types that evolved during adaptation to diverse climatic environments in maize through phylogenetic and haplotype analyses.Comparative analyses revealed obvious genetic differences between heterotic groups and germplasm resources at both the chloroplast and nuclear genome levels,especially in the unique heterotic groups HG1 and HG2,which exhibited distinct regionality and genetic uniqueness.The divergent differentiation of heterotic groups from germplasm resources was driven by differential selection in specific genomic regions.Genome-wide selective sweep analysis identified core selected regions and candidate selected genes associated with traits between heterotic groups,highlighting that stress response-and plant defense-related genes were selected for environmental adaptation across a broad latitudinal range in China.Meanwhile,a genome-wide association study analysis provided evidence that core selected genes served as an important candidate gene pool with a potential role in genetic improvement.Gene exchanges among heterotic groups,which avoided the predominant heterotic patterns as much as possible,occurred to achieve population improvement during modern maize breeding.This study provides insights into the population differentiation and genetic characteristics of heterotic groups,which will facilitate the utilization of germplasm resources,the creation of novel maize germplasm,and the optimization of heterotic patterns during future maize breeding in China.
基金This work was supported by National Natural Science Foundation of China(11305083)in part by the Fundamental Research Funds for the Central Universities under Grant lzujbky-2016-27。
文摘Aims:In this work,we evaluated the performance of three pitches positron emission tomography(PET)detectors for building a high-resolution small-animal PET imaging experimental platform.Methods:The evaluation of PET detectors includes twodimensional crystal identification,energy resolution,and crystal look-up table.The nuclear instrumentation module and PXI data acquisition(DAQ)system were both used to obtain flood images.The energy spectrum of the Na-22 source was measured.PET detectors of 2.0 and 1.6 mm pitches used in our present experiment were composed of lutetium yttrium oxyorthosilicate(LYSO)crystals directly coupled to position-sensitive photomultiplier tubes(PSPMTs).The 1.3-mm pitch detector comprises a LYSO crystal,a tapered light-guide,and a PSPMT.The crystal sizes of the detectors were a 10×10 array of 2.0×2.0×10 mm^(3) crystals,a 10×10 array of 1.6×1.6×10 mm^(3) crystals,and an 18×18 array of 1.3×1.3×10 mm^(3) crystals,respectively.Due to the lower sampling frequency of the DAQ system,a spline interpolation algorithm was introduced in the signal waveform to reconstruct the peak values.Results:The experimental results indicated that all three PET detector crystals could be clearly identified.A detailed analysis demonstrated that the key characteristic full width at half maximum(FWHM)values of the crystals profile could reach 0.46±0.03,0.32±0.03,and 0.21±0.02 mm,while the crystal average energy resolutions were 16.8%±1.76%,20.1%±2.24%,and 31.5%±3.76%,which correspond to pitches of 2.0-,1.6-,and 1.3-mm,respectively.Conclusions:The PET detector modules of LYSO crystal arrays could be potentially used in the small-animal PET imaging applications and are promising to achieve submillimeter PET images.
基金supported by the Key Technologies Support Program of Jiangsu Province(No.BE2013002-2)the National Key Scientific Instrument and Equipment Development Projects of China(No.2013YQ470767)
文摘We proposed a novel Al Ga N/Ga N enhancement-mode（E-mode） high electron mobility transistor（HEMT） with a dual-gate structure and carried out the detailed numerical simulation of device operation using Silvaco Atlas. The dual-gate device is based on a cascode connection of an E-mode and a D-mode gate. The simulation results show that electric field under the gate is decreased by more than 70% compared to that of the conventional E-mode MIS-HEMTs（from 2.83 MV/cm decreased to 0.83 MV/cm）. Thus, with the discussion of ionized trap density, the proposed dual-gate structure can highly improve electric field-related reliability, such as, threshold voltage stability. In addition, compared with HEMT with field plate structure, the proposed structure exhibits a simplified fabrication process and a more effective suppression of high electric field.
