A retiabte and sensitive method is developed for the detection of β-blockers which are excreted in free or conjugated forms in human urine.9 β-blockers were derivatized by MSTFA and MBTFA and subjected to GC/MSB ana...A retiabte and sensitive method is developed for the detection of β-blockers which are excreted in free or conjugated forms in human urine.9 β-blockers were derivatized by MSTFA and MBTFA and subjected to GC/MSB analysis.Both chromato- grams and mass spectrometric data were obtained from full scanning mode.This method is suitable for routine screening and confirmation of β-blockers in doping control.展开更多
Cases of foodborne doping are frequently reported in sports events and can cause severe consequences for athletes.The foodborne doping can be divided into natural endogenous and artifi cially added foods according to ...Cases of foodborne doping are frequently reported in sports events and can cause severe consequences for athletes.The foodborne doping can be divided into natural endogenous and artifi cially added foods according to the sources,including anabolic agents,stimulants,diuretics,β-blockers,β2 agonists and others.In order to control foodborne doping,chromatographic technique,immunoassay,nuclear magnetic resonance,biosensor technology,pyrolytic spectroscopy,comprehensive analysis and electrochemical analysis have usually used as analytical and inspection strategies.Meanwhile,the legislation of anti-doping,the improvement of testing standard and technology,and the prevention and control of food safety,as well as the improvement of risk perception of athletes are highly necessary for achieving the effective risk control and supervision of foodborne doping,which will be benefi cial for athletes,doctors and administrators to avoid the risks of foodborne doping test and reduce foodborne doping risks for the health of athletes.展开更多
With the Rio Olympics just a few months past,we remember the excitement,the incredible performances,and the controversies.As happens so often,the Olympic Games focus attention not only on athletic achievements but als...With the Rio Olympics just a few months past,we remember the excitement,the incredible performances,and the controversies.As happens so often,the Olympic Games focus attention not only on athletic achievements but also on how athletes may reach ever-increasing levels of performance.Doping,medical展开更多
We demonstrate an electric-controlled terahertz（THz） modulator which can be used to realize amplitude modulation of terahertz waves with slight photo-doping. The THz pulse transmission was efficiently modulated by e...We demonstrate an electric-controlled terahertz（THz） modulator which can be used to realize amplitude modulation of terahertz waves with slight photo-doping. The THz pulse transmission was efficiently modulated by electrically controlling the monolayer silicon-based device. The modulation depth reached 100% almost when the applied voltage was 7V at an external laser intensity of 0.6W/cm2. The saturation voltage reduced with the increase of the photo-excited intensity. In a THz continuous wave（CW）system, a significant fall in both THz transmission and reflection was also observed with the increase of applied voltage. This reduction in the THz transmission and reflection was induced by the absorption for electron injection. The results show that a high-efficiency and high modulation depth broadband electric-controlled terahertz modulator in a pure Si structure has been realized.展开更多
Substitutional doping of two-dimensional(2D)transition metal dichalcogenides(TMDs)has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllab...Substitutional doping of two-dimensional(2D)transition metal dichalcogenides(TMDs)has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllable doping of TMDs remains a challenging issue due to the natural doping of these materials.Here,we demonstrate the controllable growth of indium-doped p-type WS_(2) monolayers with various doping concentrations via chemical vapor deposition(CVD)of a host tungsten(W)source and indium(In)dopant.Scanning transmission electron microscopy confirmed that In atoms successfully substitute the W atoms in the WS_(2) lattice.Intriguingly,the photoluminescence of the doped sample experiences strong intensity modulation by the doping concentration,which first increases remarkably with an enhancement factor up to~35 and then decreases gradually when further increasing the doping concentration.Such a phenomenon is attributed to the progressive change of the exciton to trion ratio as well as the defect concentration in the doped samples.The assignment was further verified by the electric behavior of the fabricated In-doped WS_(2) field effect transistors,which changes regularly from n-type to bipolar and finally to p-type behavior with increasing doping concentration.The successful growth of p-type monolayer WS_(2) and the dual control of its optical and electrical properties by In doping may provide a promising method to engineer the opto-electronic properties of 2D materials.展开更多
Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions,which would have a significant effect on the growth process of the materials.However,the controlling s...Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions,which would have a significant effect on the growth process of the materials.However,the controlling strategy is limited into high concentration of lanthanide doping,which produces concentration quenching of the lanthanide ion luminescence with an increase in the Ln^(3+)concentration,resulting in lowering the fluorescence quantum yield of lanthanide ion.Herein,for the first time,we demonstrate simultaneous control of the structures and luminescence properties of BaCO_3nanocrystals via a small amount of Tb^(3+)doping strategy.In fact,Tb^(3+)would partially occupy Ba^(2+)sites,resulting in the changes to the structures of the BaCO_3nanocrystals,which is primarily determined by charge modulation,including the contributions from the surfaces of crystal nuclei and building blocks.These structurally modified nanocrystals exhibit tunable luminescence properties,thus emerging as potential candidates for photonic devices such as light-emitting diodes and color displays.展开更多
本研究利用一步化学气相沉积技术制备了Sn_(x)Mo_(1−x)S_(2)/MoS_(2)横向异质结高性能二极管.通过选择性掺杂Sn原子到单层MoS_(2)的边缘,形成了与MoS_(2)相同晶格常数的Sn_(x)Mo_(1−x)S_(2).在边缘的Sn_(x)Mo_(1−x)S_(2)和内部的MoS_(2...本研究利用一步化学气相沉积技术制备了Sn_(x)Mo_(1−x)S_(2)/MoS_(2)横向异质结高性能二极管.通过选择性掺杂Sn原子到单层MoS_(2)的边缘,形成了与MoS_(2)相同晶格常数的Sn_(x)Mo_(1−x)S_(2).在边缘的Sn_(x)Mo_(1−x)S_(2)和内部的MoS_(2)上分别沉积铬/金电极,形成肖特基势垒,其中势垒高度不同导致载流子仅在一个方向上传输.通过控制掺杂浓度和栅极电压,可实现MoS_(2)和Sn_(x)Mo_(1−x)S_(2)之间费米能级的对齐调节,实现了可调整的整流比,最高达到104.令人印象深刻的是,该二极管还表现出优异的光伏特性,该器件在λ=400 nm处实现了40%的外量子效率值.此外,我们在无外部偏压条件下实现了自供电光电探测,该异质结二极管在400和650 nm波长处的响应率分别为0.12和0.16 A W^(-1).对应的探测率分别是4.9×10^(10)和6.4×10^(10)Jones.可调的掺杂浓度为进一步创造高效器件提供了可能.这种合成二维侧向二极管的策略丰富了异质结二极管的材料多样性,并为开发新型电子和光电器件提供了新的平台.展开更多
Screening and confirmation methods of the major urinary metabolite of finasteride–carboxy-finasteride for doping control purpose were developed.Liquid–liquid extraction was adopted for the sample preparation.Analyte...Screening and confirmation methods of the major urinary metabolite of finasteride–carboxy-finasteride for doping control purpose were developed.Liquid–liquid extraction was adopted for the sample preparation.Analytes were detected by positive electrospray ionization in single quadrupole and triple quadrupole mass spectrometer.In the screening method,selected ion monitoring(SIM)mode was used to monitor m/z 403 for carboxy-finasteride.In the confirmation method,product ion mode was used to monitor the precursor ion m/z 403.The limit of detection was below 2 ng/mL for the screening method.Good linearity was obtained in the range 10.0–500.0 ng/mL.The intra-run and inter-run precision calculated from quality control(QC)samples was less than 5.3%.The accuracy as determined from QC samples was within ±6.6%.The screening method was applied for the analysis of excretion samples,allowing the detection of carboxy-finasteride for up to 49 h in urine specimen collected after an oral administration of 5 mg of finasteride.展开更多
文摘A retiabte and sensitive method is developed for the detection of β-blockers which are excreted in free or conjugated forms in human urine.9 β-blockers were derivatized by MSTFA and MBTFA and subjected to GC/MSB analysis.Both chromato- grams and mass spectrometric data were obtained from full scanning mode.This method is suitable for routine screening and confirmation of β-blockers in doping control.
基金financially supported by the Donghu Xuezi Program from Wuhan Sports University in China to Wei Chenthe Key Special Project of Disciplinary Development, Hubei Superior Discipline Groups of Physical Education and Health Promotionthe Chutian Scholar Program and Innovative Start-Up Foundation from Wuhan Sports University to Ning Chen。
文摘Cases of foodborne doping are frequently reported in sports events and can cause severe consequences for athletes.The foodborne doping can be divided into natural endogenous and artifi cially added foods according to the sources,including anabolic agents,stimulants,diuretics,β-blockers,β2 agonists and others.In order to control foodborne doping,chromatographic technique,immunoassay,nuclear magnetic resonance,biosensor technology,pyrolytic spectroscopy,comprehensive analysis and electrochemical analysis have usually used as analytical and inspection strategies.Meanwhile,the legislation of anti-doping,the improvement of testing standard and technology,and the prevention and control of food safety,as well as the improvement of risk perception of athletes are highly necessary for achieving the effective risk control and supervision of foodborne doping,which will be benefi cial for athletes,doctors and administrators to avoid the risks of foodborne doping test and reduce foodborne doping risks for the health of athletes.
文摘With the Rio Olympics just a few months past,we remember the excitement,the incredible performances,and the controversies.As happens so often,the Olympic Games focus attention not only on athletic achievements but also on how athletes may reach ever-increasing levels of performance.Doping,medical
基金supported by the Natural Science Foundation of Beijing under Grant No.4144069the Science and Technology Project of Beijing Municipal Education Commission under Grant No.KM201410028004
文摘We demonstrate an electric-controlled terahertz（THz） modulator which can be used to realize amplitude modulation of terahertz waves with slight photo-doping. The THz pulse transmission was efficiently modulated by electrically controlling the monolayer silicon-based device. The modulation depth reached 100% almost when the applied voltage was 7V at an external laser intensity of 0.6W/cm2. The saturation voltage reduced with the increase of the photo-excited intensity. In a THz continuous wave（CW）system, a significant fall in both THz transmission and reflection was also observed with the increase of applied voltage. This reduction in the THz transmission and reflection was induced by the absorption for electron injection. The results show that a high-efficiency and high modulation depth broadband electric-controlled terahertz modulator in a pure Si structure has been realized.
基金financially supported by the National Natural Science Foundation of China (51525202, 61635001, 52072117 and 21703059)the Key Program of the Hunan Provincial Science and Technology Department (2019XK2001)the International Science and Technology Innovation Cooperation Base of Hunan Province (2018WK4004)
文摘Substitutional doping of two-dimensional(2D)transition metal dichalcogenides(TMDs)has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllable doping of TMDs remains a challenging issue due to the natural doping of these materials.Here,we demonstrate the controllable growth of indium-doped p-type WS_(2) monolayers with various doping concentrations via chemical vapor deposition(CVD)of a host tungsten(W)source and indium(In)dopant.Scanning transmission electron microscopy confirmed that In atoms successfully substitute the W atoms in the WS_(2) lattice.Intriguingly,the photoluminescence of the doped sample experiences strong intensity modulation by the doping concentration,which first increases remarkably with an enhancement factor up to~35 and then decreases gradually when further increasing the doping concentration.Such a phenomenon is attributed to the progressive change of the exciton to trion ratio as well as the defect concentration in the doped samples.The assignment was further verified by the electric behavior of the fabricated In-doped WS_(2) field effect transistors,which changes regularly from n-type to bipolar and finally to p-type behavior with increasing doping concentration.The successful growth of p-type monolayer WS_(2) and the dual control of its optical and electrical properties by In doping may provide a promising method to engineer the opto-electronic properties of 2D materials.
基金supported by the National Natural Science Foundation of China (21403189, 21371149) Natural Science Foundation of Hebei Province (B2017203198)+1 种基金China Postdoctoral Science Foundation (2014M551047)Yanshan University Doctoral Foundation (B790)
文摘Rare earth doping has been widely applied in many functional nanomaterials with desirable properties and functions,which would have a significant effect on the growth process of the materials.However,the controlling strategy is limited into high concentration of lanthanide doping,which produces concentration quenching of the lanthanide ion luminescence with an increase in the Ln^(3+)concentration,resulting in lowering the fluorescence quantum yield of lanthanide ion.Herein,for the first time,we demonstrate simultaneous control of the structures and luminescence properties of BaCO_3nanocrystals via a small amount of Tb^(3+)doping strategy.In fact,Tb^(3+)would partially occupy Ba^(2+)sites,resulting in the changes to the structures of the BaCO_3nanocrystals,which is primarily determined by charge modulation,including the contributions from the surfaces of crystal nuclei and building blocks.These structurally modified nanocrystals exhibit tunable luminescence properties,thus emerging as potential candidates for photonic devices such as light-emitting diodes and color displays.
基金supported by the National Key R&D Program of China(2022YFA1505200,2018YFA0306900)the National Natural Science Foundation of China(21872114,92163103)the Fundamental Research Funds for the Central Universities(20720210009)。
文摘本研究利用一步化学气相沉积技术制备了Sn_(x)Mo_(1−x)S_(2)/MoS_(2)横向异质结高性能二极管.通过选择性掺杂Sn原子到单层MoS_(2)的边缘,形成了与MoS_(2)相同晶格常数的Sn_(x)Mo_(1−x)S_(2).在边缘的Sn_(x)Mo_(1−x)S_(2)和内部的MoS_(2)上分别沉积铬/金电极,形成肖特基势垒,其中势垒高度不同导致载流子仅在一个方向上传输.通过控制掺杂浓度和栅极电压,可实现MoS_(2)和Sn_(x)Mo_(1−x)S_(2)之间费米能级的对齐调节,实现了可调整的整流比,最高达到104.令人印象深刻的是,该二极管还表现出优异的光伏特性,该器件在λ=400 nm处实现了40%的外量子效率值.此外,我们在无外部偏压条件下实现了自供电光电探测,该异质结二极管在400和650 nm波长处的响应率分别为0.12和0.16 A W^(-1).对应的探测率分别是4.9×10^(10)和6.4×10^(10)Jones.可调的掺杂浓度为进一步创造高效器件提供了可能.这种合成二维侧向二极管的策略丰富了异质结二极管的材料多样性,并为开发新型电子和光电器件提供了新的平台.
文摘Screening and confirmation methods of the major urinary metabolite of finasteride–carboxy-finasteride for doping control purpose were developed.Liquid–liquid extraction was adopted for the sample preparation.Analytes were detected by positive electrospray ionization in single quadrupole and triple quadrupole mass spectrometer.In the screening method,selected ion monitoring(SIM)mode was used to monitor m/z 403 for carboxy-finasteride.In the confirmation method,product ion mode was used to monitor the precursor ion m/z 403.The limit of detection was below 2 ng/mL for the screening method.Good linearity was obtained in the range 10.0–500.0 ng/mL.The intra-run and inter-run precision calculated from quality control(QC)samples was less than 5.3%.The accuracy as determined from QC samples was within ±6.6%.The screening method was applied for the analysis of excretion samples,allowing the detection of carboxy-finasteride for up to 49 h in urine specimen collected after an oral administration of 5 mg of finasteride.
