A novel up-converting phosphor,Na_xAl_yF_（x＋3y）/CaF2（0.3 〈 x 〈 0.5,0 〈 y 〈 0.1） composite,is prepared by a hydrothermal process at 180°C and an annealing treatment at 500℃.X-ray diffraction（XRD） patte...A novel up-converting phosphor,Na_xAl_yF_（x＋3y）/CaF2（0.3 〈 x 〈 0.5,0 〈 y 〈 0.1） composite,is prepared by a hydrothermal process at 180°C and an annealing treatment at 500℃.X-ray diffraction（XRD） pattern indicates that Na_xAl_yF_（x＋3y）/CaF_2 is a composite consisting of NaF,Na_3 AlF_6,and CaF_2.The up-conversion luminescence properties of this phosphor are investigated by fluorescence spectrometer.Results show that Na_xAl_yF_（x＋3y）/CaF_2 exhibits visible-to-ultraviolet up-conversion luminescence properties.The emission peaks at 316 and 336 nm are observed when excited by 610 nm,the luminescence lifetime of the emissions is great than 18 ms,and the internal fluorescence quantum yield is 4.2%.Additionally,the luminescent mechanism of this phosphor is also mentioned.展开更多
Background:Methodological applications of the high sensitivity genus-specific Schistosoma CAA strip test,allowing detection of single worm active infections(ultimate sensitivity),are discussed for efficient utilizatio...Background:Methodological applications of the high sensitivity genus-specific Schistosoma CAA strip test,allowing detection of single worm active infections(ultimate sensitivity),are discussed for efficient utilization in sample pooling strategies.Besides relevant cost reduction,pooling of samples rather than individual testing can provide valuable data for large scale mapping,surveillance,and monitoring.Method:The laboratory-based CAA strip test utilizes luminescent quantitative up-converting phosphor(UCP)reporter particles and a rapid user-friendly lateral flow(LF)assay format.The test includes a sample preparation step that permits virtually unlimited sample concentration with urine,reaching ultimate sensitivity(single worm detection)at 100%specificity.This facilitates testing large urine pools from many individuals with minimal loss of sensitivity and specificity.The test determines the average CAA level of the individuals in the pool thus indicating overall worm burden and prevalence.When requiring test results at the individual level,smaller pools need to be analysed with the pool-size based on expected prevalence or when unknown,on the average CAA level of a larger group;CAA negative pools do not require individual test results and thus reduce the number of tests.Results:Straightforward pooling strategies indicate that at sub-population level the CAA strip test is an efficient assay for general mapping,identification of hotspots,determination of stratified infection levels,and accurate monitoring of mass drug administrations(MDA).At the individual level,the number of tests can be reduced i.e.in low endemic settings as the pool size can be increased as opposed to prevalence decrease.Conclusions:At the sub-population level,average CAA concentrations determined in urine pools can be an appropriate measure indicating worm burden.Pooling strategies allowing this type of large scale testing are feasible with the various CAA strip test formats and do not affect sensitivity and specificity.It allows cost efficient stratified testing and monitoring of worm burden at the sub-population level,ideally for large-scale surveillance generating hard data for performance of MDA programs and strategic planning when moving towards transmission-stop and elimination.展开更多
Moderate level of exposure to the solar irradiation containing UV component is essential for health care. To incorporate the UV-emitting phosphors into the commercial YAG-based white light-emitting diode introduces th...Moderate level of exposure to the solar irradiation containing UV component is essential for health care. To incorporate the UV-emitting phosphors into the commercial YAG-based white light-emitting diode introduces the possibilities of healthy illumination to individuals＇ daily lives. 1 mol.% E3＊-doped BaGd2ZnO5（BGZ） particles were synthesized via sol-gel method and efficient up-converted luminescence peaked at 380 nm was detected under 480 nm excitation. The mixed phosphors with varied mass ratio of Er3＋：BGZ and Ce3＋：YAG particles were encapsulated to form LEDs. The study of the LEDs indicated that the introduction of BGZ component favored the enhancement of color-rendering index and the neutralization of the white light emitting. The WLED with the BGZ/YAG ratio of 8：2 was recommendable for its excellent overall white light luminous performances and UV intensity of 84.55 mW/cm2. The UV illumination dose of the WLEDs with mixed YAG and BGZ was controllable by adjusting the ratio, the illumination distance and the illumination time. Er3＋：BGZ phosphors are promising UV- emitting phosphors for healthy indoor illumination.展开更多
在高增益场合,传统Boost变换器存在增益受限、器件应力大、效率低等问题,为此,提出一种交错控制高增益零电流转移(zero current transition,ZCT)ZCT Boost变换器,详细分析其工作原理,在此基础上对其电压增益进行推导,讨论其软开关工作条...在高增益场合,传统Boost变换器存在增益受限、器件应力大、效率低等问题,为此,提出一种交错控制高增益零电流转移(zero current transition,ZCT)ZCT Boost变换器,详细分析其工作原理,在此基础上对其电压增益进行推导,讨论其软开关工作条件,特别分析考虑二极管反向恢复时变换器的工作情况。最后搭建一台额定输入电压为12 V、输出电压为100 V、输出功率为35 W的实验样机,变换效率最高达到87.7%,实验结果验证了理论分析的正确性。展开更多
基金supported by the National Natural Science Foundation of China(No.20876125)the Research Fund for the Doctoral Program of Higher Education(No.20096101110013)Northwest University Graduate Cross-discipline Funds(Nos.09YJC24 and 09YJC27)
文摘A novel up-converting phosphor,Na_xAl_yF_（x＋3y）/CaF2（0.3 〈 x 〈 0.5,0 〈 y 〈 0.1） composite,is prepared by a hydrothermal process at 180°C and an annealing treatment at 500℃.X-ray diffraction（XRD） pattern indicates that Na_xAl_yF_（x＋3y）/CaF_2 is a composite consisting of NaF,Na_3 AlF_6,and CaF_2.The up-conversion luminescence properties of this phosphor are investigated by fluorescence spectrometer.Results show that Na_xAl_yF_（x＋3y）/CaF_2 exhibits visible-to-ultraviolet up-conversion luminescence properties.The emission peaks at 316 and 336 nm are observed when excited by 610 nm,the luminescence lifetime of the emissions is great than 18 ms,and the internal fluorescence quantum yield is 4.2%.Additionally,the luminescent mechanism of this phosphor is also mentioned.
基金Part of this work related to UCP-LF CAA testing,received financial support from the University of Georgia Research Foundation,Inc.(Schistosomiasis Consortium for Operational Research and Evaluation[SCORE]project).
文摘Background:Methodological applications of the high sensitivity genus-specific Schistosoma CAA strip test,allowing detection of single worm active infections(ultimate sensitivity),are discussed for efficient utilization in sample pooling strategies.Besides relevant cost reduction,pooling of samples rather than individual testing can provide valuable data for large scale mapping,surveillance,and monitoring.Method:The laboratory-based CAA strip test utilizes luminescent quantitative up-converting phosphor(UCP)reporter particles and a rapid user-friendly lateral flow(LF)assay format.The test includes a sample preparation step that permits virtually unlimited sample concentration with urine,reaching ultimate sensitivity(single worm detection)at 100%specificity.This facilitates testing large urine pools from many individuals with minimal loss of sensitivity and specificity.The test determines the average CAA level of the individuals in the pool thus indicating overall worm burden and prevalence.When requiring test results at the individual level,smaller pools need to be analysed with the pool-size based on expected prevalence or when unknown,on the average CAA level of a larger group;CAA negative pools do not require individual test results and thus reduce the number of tests.Results:Straightforward pooling strategies indicate that at sub-population level the CAA strip test is an efficient assay for general mapping,identification of hotspots,determination of stratified infection levels,and accurate monitoring of mass drug administrations(MDA).At the individual level,the number of tests can be reduced i.e.in low endemic settings as the pool size can be increased as opposed to prevalence decrease.Conclusions:At the sub-population level,average CAA concentrations determined in urine pools can be an appropriate measure indicating worm burden.Pooling strategies allowing this type of large scale testing are feasible with the various CAA strip test formats and do not affect sensitivity and specificity.It allows cost efficient stratified testing and monitoring of worm burden at the sub-population level,ideally for large-scale surveillance generating hard data for performance of MDA programs and strategic planning when moving towards transmission-stop and elimination.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 51472263 and 51572175）, the Jiangsu Planned Projects for Postdoctoral Research Funds （1501131C）, and the Shanghai Planned Projects for Young Teacher Training of Universities （ZZyy15087）.
文摘Moderate level of exposure to the solar irradiation containing UV component is essential for health care. To incorporate the UV-emitting phosphors into the commercial YAG-based white light-emitting diode introduces the possibilities of healthy illumination to individuals＇ daily lives. 1 mol.% E3＊-doped BaGd2ZnO5（BGZ） particles were synthesized via sol-gel method and efficient up-converted luminescence peaked at 380 nm was detected under 480 nm excitation. The mixed phosphors with varied mass ratio of Er3＋：BGZ and Ce3＋：YAG particles were encapsulated to form LEDs. The study of the LEDs indicated that the introduction of BGZ component favored the enhancement of color-rendering index and the neutralization of the white light emitting. The WLED with the BGZ/YAG ratio of 8：2 was recommendable for its excellent overall white light luminous performances and UV intensity of 84.55 mW/cm2. The UV illumination dose of the WLEDs with mixed YAG and BGZ was controllable by adjusting the ratio, the illumination distance and the illumination time. Er3＋：BGZ phosphors are promising UV- emitting phosphors for healthy indoor illumination.
