A novel magnetic method using polystyrene modified magnetic nanoparticles to perform thermoheadspace extraction was successfully developed for extraction and preconcentration of volatile organic components in dry Trad...A novel magnetic method using polystyrene modified magnetic nanoparticles to perform thermoheadspace extraction was successfully developed for extraction and preconcentration of volatile organic components in dry Traditional Chinese Medicine（TCM） based on gas chromatography-ion trap/mass spectrometry with a Chromato Probe direct sample introduction device. The dried fruit of Amomum testaceum Ridl. was used as the object TCM. The optimum parameters of headspace magnetic solid-phase extraction were investigated, in which desorption solvent ethyl acetate played a key role in this method,and the headspace extraction temperature of 90℃ and the headspace extraction time of 15 min finally decided. Headspace solid-phase microextraction method was also used to analyze volatile compounds in the TCM to compare with the proposed method. The results show that 60 components were identified totally by two methods; most of the low boiling point chemical compounds are isolated by this new method. In this work, an environmental-friendly and cheap analytical method was established, and a new approach to analyze volatile compounds in dry Traditional Chinese Medicine was also provided.展开更多
A transform method was used to model a discrete time multi-tap direct sampling mixer. The method transforms the mixed filtering and down-sampling stages to separate cascade filtering and sampling stages to determine t...A transform method was used to model a discrete time multi-tap direct sampling mixer. The method transforms the mixed filtering and down-sampling stages to separate cascade filtering and sampling stages to determine the unfolded frequency response which shows the anti-aliasing ability of the mixer. The trans-formation can also be applied to other mixed signal and multi-rate receiver systems to analyze their unfolded frequency responses. The transformed system architecture was used to calculate the unfolded frequency response of the multi-tap direct sampling mixer and compared with the mixer model without noise in the advanced design system 2005A environment to further evaluate the frequency response. The simulations show that the -3 dB bandwidth is 3.0 MHz and the voltage gain is attenuated by 1.5 dB within a 1-MHz baseband bandwidth.展开更多
Color centers play key roles in,e.g.,solid state lighting and quantum information technology.Here,we describe an approach for predicting the optical line shapes of such emitters based on direct sampling of the underly...Color centers play key roles in,e.g.,solid state lighting and quantum information technology.Here,we describe an approach for predicting the optical line shapes of such emitters based on direct sampling of the underlying autocorrelation functions through molecular dynamics simulations(MD-ACF).The energy landscapes are represented by a machine-learned potential that describes both the ground and excited state landscapes through a single model,guaranteeing size-consistent predictions.We apply this methodology to the(V_(Si)V_(C))_(kk)^(0)divacancy defect in 4H-SiC and demonstrate that at low temperatures,the present MD-ACF approach reproduces results from the traditional generating function approach.Unlike the latter,it is,however,also applicable at high temperatures as it avoids harmonic and parallel-mode approximations and can be applied to study non-crystalline materials.The MD-ACF methodology thus promises to substantially widen the range of computational predictions of the optical properties of color centers and related defects.展开更多
基金Support of this work by the Department of Education of Zhejiang Province (No. Pd2013016)Hangzhou Qianjiang Distinguished Experts Project (2014)+2 种基金the Science and Technology Department of Zhejiang Province (No. 2015C32006)Key Laboratory of Detection for Pesticide Residues of Ministry of Agriculture Projectthe Sprout Talented Project Program (No. 2011443)
文摘A novel magnetic method using polystyrene modified magnetic nanoparticles to perform thermoheadspace extraction was successfully developed for extraction and preconcentration of volatile organic components in dry Traditional Chinese Medicine（TCM） based on gas chromatography-ion trap/mass spectrometry with a Chromato Probe direct sample introduction device. The dried fruit of Amomum testaceum Ridl. was used as the object TCM. The optimum parameters of headspace magnetic solid-phase extraction were investigated, in which desorption solvent ethyl acetate played a key role in this method,and the headspace extraction temperature of 90℃ and the headspace extraction time of 15 min finally decided. Headspace solid-phase microextraction method was also used to analyze volatile compounds in the TCM to compare with the proposed method. The results show that 60 components were identified totally by two methods; most of the low boiling point chemical compounds are isolated by this new method. In this work, an environmental-friendly and cheap analytical method was established, and a new approach to analyze volatile compounds in dry Traditional Chinese Medicine was also provided.
基金Supported by the National Natural Science Foundation of China (No. 90407011)the National High-Tech Research and Development (863) Program of China (No. 2007AA01Z2b3)
文摘A transform method was used to model a discrete time multi-tap direct sampling mixer. The method transforms the mixed filtering and down-sampling stages to separate cascade filtering and sampling stages to determine the unfolded frequency response which shows the anti-aliasing ability of the mixer. The trans-formation can also be applied to other mixed signal and multi-rate receiver systems to analyze their unfolded frequency responses. The transformed system architecture was used to calculate the unfolded frequency response of the multi-tap direct sampling mixer and compared with the mixer model without noise in the advanced design system 2005A environment to further evaluate the frequency response. The simulations show that the -3 dB bandwidth is 3.0 MHz and the voltage gain is attenuated by 1.5 dB within a 1-MHz baseband bandwidth.
基金funding from the Swedish Research Council(Nos.2020-04935 and 2021-05072)as well as computational resources provided by the National Academic Infrastructure for Supercomputing in Sweden at NSC,PDCC3SE partially funded by the Swedish Research Council through grant agreement No.2022-06725+1 种基金as well as the Berzelius resource provided by the Knut and Alice Wallenberg Foundation at NSC.Parts of the computations were performed on resources provided by UNINETT Sigma2-the National Infrastructure for High-Performance Computing and Data Storage in Norway.C.L.acknowledges the support provided by the Research Council of Norway and the University of Oslo through the research project QuTe(no.325573,FriPro ToppForsk-program)funding from the Swedish Strategic Research Foundation through a Future Research Leader program(FFL21-0129).
文摘Color centers play key roles in,e.g.,solid state lighting and quantum information technology.Here,we describe an approach for predicting the optical line shapes of such emitters based on direct sampling of the underlying autocorrelation functions through molecular dynamics simulations(MD-ACF).The energy landscapes are represented by a machine-learned potential that describes both the ground and excited state landscapes through a single model,guaranteeing size-consistent predictions.We apply this methodology to the(V_(Si)V_(C))_(kk)^(0)divacancy defect in 4H-SiC and demonstrate that at low temperatures,the present MD-ACF approach reproduces results from the traditional generating function approach.Unlike the latter,it is,however,also applicable at high temperatures as it avoids harmonic and parallel-mode approximations and can be applied to study non-crystalline materials.The MD-ACF methodology thus promises to substantially widen the range of computational predictions of the optical properties of color centers and related defects.
