Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the l...Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.展开更多
[Objectives]This study was conducted to establish an ultra-high performance liquid chromatography-tandem mass spectrometry for the rapid extraction of sodium pentachlorophenoxide from animal-derived food.[Methods]The ...[Objectives]This study was conducted to establish an ultra-high performance liquid chromatography-tandem mass spectrometry for the rapid extraction of sodium pentachlorophenoxide from animal-derived food.[Methods]The samples were extracted with an acetonitrile water solution(8∶2),0.1 mol/L hydrochloric acid and a purification extraction bag with shaking.Centrifugation was performed to obtain supernatants,which were added to purification tubes containing PSA and C_(18) for purification,and then filtered with membranes for determination.Each test solution was separated by a ZORBAX Eclipse plus C_(18) column with acetonitrile and 5 mmol/L ammonium acetate as mobile phases,and determined with electrospray ionization and multiple reaction monitoring.[Results]The method had good linearity in the concentration range of 1.0-50 ng/ml,and the correlation coefficient was 0.9997.The limit of detection was 0.25μg/kg and the limit of quantification was 0.75μg/kg.The recovery was between 87.4%and 112.5%,and the RSD%was between 0.5%and 10.0%.[Conclusions]The method has simple operation and high sensitivity,and is suitable for trace detection of sodium pentachlorophenoxide in large quantities of animal-derived food.展开更多
Rainbow is an incoherent sum of sunlight refracted by many water droplets and often appears after rain in summer.Since the refraction index of water depends on the light wavelength(i.e.,the color),white light goes in ...Rainbow is an incoherent sum of sunlight refracted by many water droplets and often appears after rain in summer.Since the refraction index of water depends on the light wavelength(i.e.,the color),white light goes in and rainbow comes out.The famous Newton’s rings are coherent sum of light passing through a lens on a plane glass,showing Newton’s color under white light illuminations[1].Using single-color laser source,coherent rings were展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0301202)the National Natural Science Foundation of China(Grant Nos.11674311 and U20A20205)。
文摘Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.
文摘[Objectives]This study was conducted to establish an ultra-high performance liquid chromatography-tandem mass spectrometry for the rapid extraction of sodium pentachlorophenoxide from animal-derived food.[Methods]The samples were extracted with an acetonitrile water solution(8∶2),0.1 mol/L hydrochloric acid and a purification extraction bag with shaking.Centrifugation was performed to obtain supernatants,which were added to purification tubes containing PSA and C_(18) for purification,and then filtered with membranes for determination.Each test solution was separated by a ZORBAX Eclipse plus C_(18) column with acetonitrile and 5 mmol/L ammonium acetate as mobile phases,and determined with electrospray ionization and multiple reaction monitoring.[Results]The method had good linearity in the concentration range of 1.0-50 ng/ml,and the correlation coefficient was 0.9997.The limit of detection was 0.25μg/kg and the limit of quantification was 0.75μg/kg.The recovery was between 87.4%and 112.5%,and the RSD%was between 0.5%and 10.0%.[Conclusions]The method has simple operation and high sensitivity,and is suitable for trace detection of sodium pentachlorophenoxide in large quantities of animal-derived food.
基金partially supported by the National Key Research and Development Program of China(2016YFA0301202)the National Natural Science Foundation of China(11674311,61674146 and 61774144)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDPB06)K.C.Wong Education Foundation,China
文摘Rainbow is an incoherent sum of sunlight refracted by many water droplets and often appears after rain in summer.Since the refraction index of water depends on the light wavelength(i.e.,the color),white light goes in and rainbow comes out.The famous Newton’s rings are coherent sum of light passing through a lens on a plane glass,showing Newton’s color under white light illuminations[1].Using single-color laser source,coherent rings were
