Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the r...Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.展开更多
Deactivation is common in cerebral functional imaging. However, the physiological mechanisms responsible for this phenomenon remain poorly understood. The present study analyzed 12 ischemic stroke patients, who were r...Deactivation is common in cerebral functional imaging. However, the physiological mechanisms responsible for this phenomenon remain poorly understood. The present study analyzed 12 ischemic stroke patients, who were randomly assigned to two groups： one group underwent sham needling and true needling at the Waiguan （SJ 5） in the healthy upper limb and the other group underwent sham and true needling at a sham point. Functional magnetic resonance imaging results showed no activation points in brain tissues following needling at SJ 5. However, compared with sham needling at SJ 5, true needling at SJ 5 deactivated Broadmann 4, 6, 24, and 32 areas. In addition, compared to needling at the sham point, true needling at SJ 5 deactivated bilateral hypothalamus. Results demonstrated that SJ 5 needling in the healthy upper limb resulted in specific directional brain action, as manifested by deactivation of cerebral areas related to motor （Broadmann 4 and 6）, emotion （hypothalamus）, and cognition （Broadmann 24, 32）.展开更多
The Taihang Mountains area is an area in North China where serious mudflow hazards take place frequently. The hazards often obstrust traffic and make it difficult to carry out conventional ground investigations of the...The Taihang Mountains area is an area in North China where serious mudflow hazards take place frequently. The hazards often obstrust traffic and make it difficult to carry out conventional ground investigations of the mudflow hazards. This paper introduces the feasibility study of mudflow hazards by using Landsat-5TM data. The study has achieved a great success through adopting both the faint spectral enhancement technique for mudflow fans (or other depositional areas) and comprehensive study of the environmental background of pregnant mudflows. Thus, remote sensing as a fast, convenient, low-cost and effective technical method can be used to recognise the situation of mudflow hazards so that effective rescue can be provided.展开更多
基金the financially support of the National Natural Science Foundation of China(12164051)the Joint Foundation of Provincial Science and Technology Department-Double First-class Construction of Yunnan University(2019FY003016)+4 种基金the Young Top Talent Project of Yunnan Province(YNWR-QNBJ-2018-229)the financially support by Yunnan Major Scientific and Technological Projects(202202AG050016)Advanced Analysis and Measurement Center of Yunnan University for the sample characterization service and the Postgraduate Research and Innovation Foundation of Yunnan University(2021Y036)the financially support of the National Natural Science Foundation of China(62064013)the Application Basic Research Project of Yunnan Province[2019FB130]。
文摘Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.
基金the National Basic Research Program of China (973 Program), No. 2006CB504505, 2012CB518504the 3 re Key Construction Program of "211 Project" of Guangdong Province
文摘Deactivation is common in cerebral functional imaging. However, the physiological mechanisms responsible for this phenomenon remain poorly understood. The present study analyzed 12 ischemic stroke patients, who were randomly assigned to two groups： one group underwent sham needling and true needling at the Waiguan （SJ 5） in the healthy upper limb and the other group underwent sham and true needling at a sham point. Functional magnetic resonance imaging results showed no activation points in brain tissues following needling at SJ 5. However, compared with sham needling at SJ 5, true needling at SJ 5 deactivated Broadmann 4, 6, 24, and 32 areas. In addition, compared to needling at the sham point, true needling at SJ 5 deactivated bilateral hypothalamus. Results demonstrated that SJ 5 needling in the healthy upper limb resulted in specific directional brain action, as manifested by deactivation of cerebral areas related to motor （Broadmann 4 and 6）, emotion （hypothalamus）, and cognition （Broadmann 24, 32）.
文摘The Taihang Mountains area is an area in North China where serious mudflow hazards take place frequently. The hazards often obstrust traffic and make it difficult to carry out conventional ground investigations of the mudflow hazards. This paper introduces the feasibility study of mudflow hazards by using Landsat-5TM data. The study has achieved a great success through adopting both the faint spectral enhancement technique for mudflow fans (or other depositional areas) and comprehensive study of the environmental background of pregnant mudflows. Thus, remote sensing as a fast, convenient, low-cost and effective technical method can be used to recognise the situation of mudflow hazards so that effective rescue can be provided.
