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Transient electromagnetically induced transparency spectroscopy of^(87)Rb atoms in buffer gas

Chinese Physics B 2022年第7期31卷 235-240页

作者： Zi-Shan Xu Han-Mu Wang Zeng-Li Ba Hong-Ping Liu State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China School of Physical Science University of Science and Technology of ChinaHefei 230026China

We study the transient response dynamics of^(87)Rb atomic vapor buffered in 8 torr Ne gas through an electromagnetically induced transparency configured inΛ-***,the temporal transmission spectra versus probe detuning by switching on and off the coupling one show complex *** transmitted probe light intensity drops to a minimum value when the coupling light turns off,showing a strong *** at the moment of turning on the coupling light at a subsequent delayed time,the atomic medium shows a fast transient *** account for the transient switching feature,in the time-dependent optical Bloch equation,we must take the transverse relaxation dephasing process of atomic vapor into account,as well as the fluorescence relaxation along with the optical *** work supplies a technique to quantify the transverse relaxation time scale and to sensitively monitor its variation along the environment by observing the transient dynamics of coherent medium,which is helpful in characterizing the coherent feature of the atomic medium.

关键词： electromagnetically induced transparency rubidium atom transverse relaxation rate

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Low-field NMR micro coils based on printed circuit board technology

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Science China(Technological Sciences) 2014年第10期57卷 2082-2088页

作者： WU WeiPing LU RongSheng ZHOU XinLong ZHANG YunYi NI ZhongHua Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments Southeast University School of Mechanical Engineering Southeast University

Radiofrequency coil is one of the most important components for a nuclear magnetic resonance(NMR)*** this article,some planar micro coils with an inner diameter of 2 mm and number of turns that varied from 1 to 11 were investigated based on the printed circuit board(PCB)*** electrical characterization of micro coils show that self-resonant frequencies are larger than 200 ***,an NMR measurement platform with a static magnetic field of 0.66 T was constructed and the signal to noise ratio(SNR)values of the NMR were *** was found that the SNR is optimal when the turn number of the micro coils is six and the excitation time of a 90°pulse is 0.8?***,we used the micro coil with six turns to study the transverse relaxation rate of copper sulfate pentahydrate aqueous solution with different *** was found that the transverse relaxation rate is proportional to the solution *** from the micro coil were verified by measurements using a Bruker Minispec MQ60.

关键词： printed circuit board planar micro coil low-field nuclear magnetic resonance signal to noise ratio transverse relaxation rate

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Difference Analysis of MRI Apparent Diffusion Coefficient and R_(2)^(*)Value Between Small Hepatocellular Carcinoma and Cirrhosis Nodules

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Advances in Modern Oncology Research 2020年第2期6卷 21-24页

作者： Man Li Haiquan Wang Liaoning University of Traditional Chinese Medicine ShenyangChina Fleming Research Center of Life Sciences Singapore

Objective:To investigate the differences of apparent diffusion coefficient and transverse relaxation rate(R_(2)^(*))in magnetic resonance imaging(MRI)between micro hepatocellular carcinoma and nodules of ***:The clinical data of 68 patients with micro hepatocellular carcinoma(76 lesions)and 45 patients with nodular cirrhosis(48 lesions)were retrospectively *** weighted imaging and R_(2)^(*)imaging were performed on all *** differences of apparent diffusion coefficient and R_(2)^(*)values in patients with micro hepatocellular carcinoma and nodular cirrhosis were *** operating characteristic(ROC)curves were drawn to evaluate the diagnostic efficacy of apparent diffusion coefficient values and R_(2)^(*)values for microhepatocellular ***:Compared with nodules of cirrhosis,the mean apparent diffusion coefficient and R_(2)^(*)value of micro-hepatocellular carcinoma were significantly decreased(P<0.05).The diagnosis threshold of apparent diffusion coefficient is at 1.35×10^(-3)mm^(2)/s,and the sensitivity for the diagnosis of micro-hepatocellular carcinoma was 80.88%,and the specificity was 91.11%,and the corresponding area under the ROC curve was 0.88;The diagnostic threshold for R_(2)^(*)value was at 53.96 Hz,and the sensitivity for the diagnosis of small hepatocellular carcinoma was 91.18%,and the specificity was 77.78%,and the corresponding area under the ROC curve was ***:MRI apparent diffusion coefficient value and R_(2)^(*)value can be used to differentiate and diagnose micro hepatocellular carcinoma and nodules of cirrhosis,in which the apparent diffusion coefficient of nodules of cirrhosis was less than 1.35×10^(-3)mm^(2)/s,R_(2)^(*)values were lower than 53.96 Hz may indicate the occurrence of nodular canceration.

关键词： Small liver cancer Cirrhosis nodules Magnetic resonance imaging Apparent diffusion coefficient transverse relaxation rate

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