Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate.Dark-current densities of 7.2×10^(-7)A/cm^(2) at 0 V and 3.6×10^(-4...Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate.Dark-current densities of 7.2×10^(-7)A/cm^(2) at 0 V and 3.6×10^(-4)A/cm^(2) at-5 V,a high quantum efficiency of 74.4%at 1546nm,and a 3-dB bandwidth up to 12GHz are achieved.The full width at half maximum of the detector is about 16nm.Furthermore,through thermal tuning,the peak wavelength red shifts from 1527nm to 1544 nm,and a tuning range of 17nm is realized without fabricating extra tuning electrodes.展开更多
【目的】将改良版叠氮溴化丙锭(improved propidium monoazide,PMAxx)与微滴式数字PCR(droplet digital PCR,ddPCR)技术相结合,建立一种针对单核细胞增生李斯特氏菌(Listeria monocytogenes,LM)活菌的检测方法。【方法】对PMAxx终浓度...【目的】将改良版叠氮溴化丙锭(improved propidium monoazide,PMAxx)与微滴式数字PCR(droplet digital PCR,ddPCR)技术相结合,建立一种针对单核细胞增生李斯特氏菌(Listeria monocytogenes,LM)活菌的检测方法。【方法】对PMAxx终浓度、暗处理时间及曝光时间进行优化,建立最佳的PMAxx-ddPCR检测体系,并用不同体积比的LM活菌验证其准确性,考察PMAxx-ddPCR检测方法的特异性、灵敏性和重复性。用不同浓度LM活菌与死菌对奶酪棒样品进行人工污染,比较传统的平板计数法和作者建立的PMAxx-ddPCR检测方法的结果;进一步对市售金针菇和火腿肠进行检测,评估PMAxx-ddPCR检测方法的实际效果。【结果】在PMAxx终浓度为10μmol/L、暗处理时间和曝光时间均为10 min时,PMAxx可显著抑制死菌DNA扩增,但对活菌DNA扩增没有显著影响。建立的PMAxx-ddPCR检测方法仅对LM产生特异性扩增,定量限为147 CFU/mL,相对标准偏差(relative standard deviation,RSD)均小于20%,重复性较好。人工污染奶酪棒试验结果表明,平板计数法和PMAxx-ddPCR检测方法对LM的定量结果差异不显著(P>0.05)。进一步分析17份金针菇和16份火腿肠样品检测结果,PMAxx-ddPCR检测法和平板计数法均从7份金针菇样品中检出LM,且2种方法定量结果没有显著差异(P>0.05)。【结论】作者建立的LM活菌的PMAxx-ddPCR检测方法可对食品中LM活菌进行特异性定量检测。展开更多
A separate absorption,grading,charge and multiplication InGaAs/InP avalanche photodiode with ultra low dark current and high responsivity is demonstrated.It has a thin multiplication layer and a planar structure.Throu...A separate absorption,grading,charge and multiplication InGaAs/InP avalanche photodiode with ultra low dark current and high responsivity is demonstrated.It has a thin multiplication layer and a planar structure.Through the use of a well and a single floating guard ring to suppress edge breakdown,the device can easily be fabricated by one step epitaxial growth and one step diffusion.The dark current of a 30μm diameter device is as low as 0.028 nA at punch-through and 0.1 nA at 90%of the breakdown voltage.The responsivity at 1.55μm is 0.93 A/W at unity gain and the multiplication layer is estimated to be less than 300 nm.展开更多
Lane detection based on machine vision,a key application in intelligent transportation,is generally characterized by gradient information of lane edge and plays an important role in advanced driver assistance systems(...Lane detection based on machine vision,a key application in intelligent transportation,is generally characterized by gradient information of lane edge and plays an important role in advanced driver assistance systems(ADAS).However,gradient information varies with illumination changes.In the complex scenes of urban roads,highlight and shadow have effects on the detection,and non-lane objects also lead to false positives.In order to improve the accuracy of detection and meet the robustness requirement,this paper proposes a method of using top-hat transformation to enhance the contrast and filter out the interference of non-lane objects.And then the threshold segmentation algorithm based on local statistical information and Hough transform algorithm with polar angle and distance constraint are used for lane fitting.Finally,Kalman filter is used to correct lane lines which are wrong detected or missed.The experimental results show that computation times meet the real-time requirements,and the overall detection rate of the proposed method is 95.63%.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 60876039 and 61176053the Hi-Tech Research and Development Program of China(863 Program)under Grant No 2009AA03Z404the National Basic Research Program of China(973 Program)under Grant No 2010CB327601.
文摘Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate.Dark-current densities of 7.2×10^(-7)A/cm^(2) at 0 V and 3.6×10^(-4)A/cm^(2) at-5 V,a high quantum efficiency of 74.4%at 1546nm,and a 3-dB bandwidth up to 12GHz are achieved.The full width at half maximum of the detector is about 16nm.Furthermore,through thermal tuning,the peak wavelength red shifts from 1527nm to 1544 nm,and a tuning range of 17nm is realized without fabricating extra tuning electrodes.
文摘【目的】将改良版叠氮溴化丙锭(improved propidium monoazide,PMAxx)与微滴式数字PCR(droplet digital PCR,ddPCR)技术相结合,建立一种针对单核细胞增生李斯特氏菌(Listeria monocytogenes,LM)活菌的检测方法。【方法】对PMAxx终浓度、暗处理时间及曝光时间进行优化,建立最佳的PMAxx-ddPCR检测体系,并用不同体积比的LM活菌验证其准确性,考察PMAxx-ddPCR检测方法的特异性、灵敏性和重复性。用不同浓度LM活菌与死菌对奶酪棒样品进行人工污染,比较传统的平板计数法和作者建立的PMAxx-ddPCR检测方法的结果;进一步对市售金针菇和火腿肠进行检测,评估PMAxx-ddPCR检测方法的实际效果。【结果】在PMAxx终浓度为10μmol/L、暗处理时间和曝光时间均为10 min时,PMAxx可显著抑制死菌DNA扩增,但对活菌DNA扩增没有显著影响。建立的PMAxx-ddPCR检测方法仅对LM产生特异性扩增,定量限为147 CFU/mL,相对标准偏差(relative standard deviation,RSD)均小于20%,重复性较好。人工污染奶酪棒试验结果表明,平板计数法和PMAxx-ddPCR检测方法对LM的定量结果差异不显著(P>0.05)。进一步分析17份金针菇和16份火腿肠样品检测结果,PMAxx-ddPCR检测法和平板计数法均从7份金针菇样品中检出LM,且2种方法定量结果没有显著差异(P>0.05)。【结论】作者建立的LM活菌的PMAxx-ddPCR检测方法可对食品中LM活菌进行特异性定量检测。
基金Supported by the National Natural Science Foundation of China under Grant Nos 61176053,61274069,61021003the National Key Basic Research Program of China under Grant No 2012CB933503the National High-Technology Research and Development Program of China under Grant No 2012AA012202.
文摘A separate absorption,grading,charge and multiplication InGaAs/InP avalanche photodiode with ultra low dark current and high responsivity is demonstrated.It has a thin multiplication layer and a planar structure.Through the use of a well and a single floating guard ring to suppress edge breakdown,the device can easily be fabricated by one step epitaxial growth and one step diffusion.The dark current of a 30μm diameter device is as low as 0.028 nA at punch-through and 0.1 nA at 90%of the breakdown voltage.The responsivity at 1.55μm is 0.93 A/W at unity gain and the multiplication layer is estimated to be less than 300 nm.
文摘Lane detection based on machine vision,a key application in intelligent transportation,is generally characterized by gradient information of lane edge and plays an important role in advanced driver assistance systems(ADAS).However,gradient information varies with illumination changes.In the complex scenes of urban roads,highlight and shadow have effects on the detection,and non-lane objects also lead to false positives.In order to improve the accuracy of detection and meet the robustness requirement,this paper proposes a method of using top-hat transformation to enhance the contrast and filter out the interference of non-lane objects.And then the threshold segmentation algorithm based on local statistical information and Hough transform algorithm with polar angle and distance constraint are used for lane fitting.Finally,Kalman filter is used to correct lane lines which are wrong detected or missed.The experimental results show that computation times meet the real-time requirements,and the overall detection rate of the proposed method is 95.63%.
