A new kinetic spectrophotometric method is developed for the measurement of manganese(Ⅱ) in water. The method is based on the catalytic effect of manganese(Ⅱ) with the oxidation of weak acid brilliant blue dye(RAWL)...A new kinetic spectrophotometric method is developed for the measurement of manganese(Ⅱ) in water. The method is based on the catalytic effect of manganese(Ⅱ) with the oxidation of weak acid brilliant blue dye(RAWL) by KIO4 using the Nitrilo triacetic acid(NTA) as an activation reagent. The optimum conditions obtained are 40 mgL-1 RAWL,1×10-4molL-1 KIO4,2×10-4 molL-1 Nitrilo triacetic acid(NTA),pH = 5.8,the reaction time of 3.00 min and the temperature of 20.0 ℃. Under the optimum conditions,the proposed method allows the measurement of manganese(Ⅱ) in a range of 0-50.0 ng mL-1 and with a detection limit of down to 0.158 ng mL-1. The recovery efficiency in measuring the standard manganese(Ⅱ) solution is in a range of 98.5%-102%,and the RSD is in a range of 0.76%-1.25%. The new method has been successfully applied to the measurement of manganese(Ⅱ) in both fresh water and seawater samples with satisfying results. Moreover,few cations and anions interfere with the measurement of manganese(Ⅱ). Compared with other kinetic catalytic methods and instrumental methods,the proposed method shows fairly good selectivity and sensitivity,low cost,cheapness,low detection limit and rapidity. It can be applied on boats easily.展开更多
High-resolution observations of high-redshift(z > 4) radio quasars offer a unique insight into jet kinematics at early cosmological epochs, as well as constraints on cosmological model parameters.Due to the general...High-resolution observations of high-redshift(z > 4) radio quasars offer a unique insight into jet kinematics at early cosmological epochs, as well as constraints on cosmological model parameters.Due to the general weakness of extremely distant objects and the apparently slow structural changes caused by cosmological time dilation, only a couple of high-redshift quasars(HRQs) have been studied with parsec-scale resolutions, and with limited number of observing epochs. Here we report on very long baseline interferometry(VLBI) observations of a high-redshift blazar J1430 + 4204(z=4.72) in the 8 GHz frequency band at five different epochs spanning 22 years. The source shows a compact core–jet structure with two jet components being identified within 3 milli-arcsecond(mas) scale. The long time span and multiple-epoch data allow for the kinematic studies of the jet components. That results in a jet proper motion of μ(J1) = 0.017 ± 0.002 mas a^-1 and μ(J2) = 0.156 ± 0.015 mas a^-1, respectively. For the fastest-moving outer jet component J2, the corresponding apparent transverse speed is (19.5 ± 1.9) c.The inferred bulk jet Lorentz factor C=14.6 ± 3.8 and viewing angle θ=2.2°± 1.6°indicate highly relativistic beaming. The Lorentz factor and apparent proper motion are the highest measured to date among the z > 4 jetted radio sources, while the jet kinematics is still consistent with the cosmological interpretation of quasar redshifts.展开更多
文摘A new kinetic spectrophotometric method is developed for the measurement of manganese(Ⅱ) in water. The method is based on the catalytic effect of manganese(Ⅱ) with the oxidation of weak acid brilliant blue dye(RAWL) by KIO4 using the Nitrilo triacetic acid(NTA) as an activation reagent. The optimum conditions obtained are 40 mgL-1 RAWL,1×10-4molL-1 KIO4,2×10-4 molL-1 Nitrilo triacetic acid(NTA),pH = 5.8,the reaction time of 3.00 min and the temperature of 20.0 ℃. Under the optimum conditions,the proposed method allows the measurement of manganese(Ⅱ) in a range of 0-50.0 ng mL-1 and with a detection limit of down to 0.158 ng mL-1. The recovery efficiency in measuring the standard manganese(Ⅱ) solution is in a range of 98.5%-102%,and the RSD is in a range of 0.76%-1.25%. The new method has been successfully applied to the measurement of manganese(Ⅱ) in both fresh water and seawater samples with satisfying results. Moreover,few cations and anions interfere with the measurement of manganese(Ⅱ). Compared with other kinetic catalytic methods and instrumental methods,the proposed method shows fairly good selectivity and sensitivity,low cost,cheapness,low detection limit and rapidity. It can be applied on boats easily.
基金This work was supported by the National Key R&D Programme of China(2018YFA0404603)the Chinese Academy of Sciences(114231KYSB20170003)+1 种基金the Hungarian National Research,Development and Innovation Office(2018-2.1.14-T T-CN-2018-00001).The authors acknowledge the use of Astrogeo Center database of brightness distributions,correlated flux densitiesimages of compact radio sources produced with VLBI.YZ thanks Shu Fengchun,Alexey Melnikov,Jamie McCallum,and Bo Xia for providing the Asia-Oceania VLBI(AOV)data and auxiliary telescope system temperature files.
文摘High-resolution observations of high-redshift(z > 4) radio quasars offer a unique insight into jet kinematics at early cosmological epochs, as well as constraints on cosmological model parameters.Due to the general weakness of extremely distant objects and the apparently slow structural changes caused by cosmological time dilation, only a couple of high-redshift quasars(HRQs) have been studied with parsec-scale resolutions, and with limited number of observing epochs. Here we report on very long baseline interferometry(VLBI) observations of a high-redshift blazar J1430 + 4204(z=4.72) in the 8 GHz frequency band at five different epochs spanning 22 years. The source shows a compact core–jet structure with two jet components being identified within 3 milli-arcsecond(mas) scale. The long time span and multiple-epoch data allow for the kinematic studies of the jet components. That results in a jet proper motion of μ(J1) = 0.017 ± 0.002 mas a^-1 and μ(J2) = 0.156 ± 0.015 mas a^-1, respectively. For the fastest-moving outer jet component J2, the corresponding apparent transverse speed is (19.5 ± 1.9) c.The inferred bulk jet Lorentz factor C=14.6 ± 3.8 and viewing angle θ=2.2°± 1.6°indicate highly relativistic beaming. The Lorentz factor and apparent proper motion are the highest measured to date among the z > 4 jetted radio sources, while the jet kinematics is still consistent with the cosmological interpretation of quasar redshifts.
