1 INTRODUCTIONSince experimental determination of the mutual liquid diffusion coefficients atinfinite dilution is rather complicated,it is important,therefore,to be able to esti-mate the coefficients under various tem...1 INTRODUCTIONSince experimental determination of the mutual liquid diffusion coefficients atinfinite dilution is rather complicated,it is important,therefore,to be able to esti-mate the coefficients under various temperatures from one available coefficient ata certain temperature such as 298K.Empirical equations for this purpose are avail-able in many forms.Typical examples are the Wilke-Chang equation and the Tynequation,given展开更多
Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in sou...Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d^-1 with the highest value occurred in the inner bay in May. Mierozooplankton grazing rates ranged from 0.5 to 3.1 d^-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate （up to 3.3 d^-1 ） was recorded for diatoms in August, while the maximum grazing rate （ up to 2.1 d ^-1 ） was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes （83%） in August, while the maximum grazing pressure on primary production was observed for eyanobacteria （up to 151% ） in December in the inner bay. Net growth rates of larger phytoplanktons （diatoms and dinoflagellates） were higher than those of smaller groups （ prasinophytes, chlorophytes and cyanobacteria）. Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons （December and February）.展开更多
The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results ...The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.展开更多
Isotope dilution(ID)method has been widely applied to studies of elemental speciation and certification of the concentrations of geological reference materials.One of the key factors restricting the application of the...Isotope dilution(ID)method has been widely applied to studies of elemental speciation and certification of the concentrations of geological reference materials.One of the key factors restricting the application of the ID method is the difficulty in identifying the optimal ratios of the isotope tracer(spike)to sample(S/N)and in estimating the error propagation.Here,using Se isotope as an example and employing a Monte Carlo method,we found that the optimal choice of spike and S/N are^(77)Se(spike)and 0.7,respectively.The S/N in the range from 0.1 to 4 can produce sufficiently low errors(<0.4%).Extending this method to other elements such as Cr,Fe,Ni,Sr,Cd and etc.,their optimal spike and S/N were also presented.According to the optimized parameters of Se,we determined the Se concentrations of geological reference materials(GRMs)by thiol cotton fiber(TCF)-hydride generation ID-MC-ICP-MS.The relative standard deviation is<5%,and the detection limit is reduced to0.1 ng/g.Most of the measured concentrations are consistent with those recommended by IGGE or reported previously.For some GRMs,discrepancies(e.g.6.90%for GSS-5)exist between our measurements and previous ones,which can be explained by the inhomogeneity of GRMs and/or the different digestion,purification and measurement methods among laboratories.展开更多
文摘1 INTRODUCTIONSince experimental determination of the mutual liquid diffusion coefficients atinfinite dilution is rather complicated,it is important,therefore,to be able to esti-mate the coefficients under various temperatures from one available coefficient ata certain temperature such as 298K.Empirical equations for this purpose are avail-able in many forms.Typical examples are the Wilke-Chang equation and the Tynequation,given
基金The National Natural Science Foundatisn of China under contract Nos 40730846 and 40521003the National Basic Key Research Program of the Ministry of Science and Technology of China (China GLOBEC-IMBER Program) under contract No.2006CB400604
文摘Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d^-1 with the highest value occurred in the inner bay in May. Mierozooplankton grazing rates ranged from 0.5 to 3.1 d^-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate （up to 3.3 d^-1 ） was recorded for diatoms in August, while the maximum grazing rate （ up to 2.1 d ^-1 ） was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes （83%） in August, while the maximum grazing pressure on primary production was observed for eyanobacteria （up to 151% ） in December in the inner bay. Net growth rates of larger phytoplanktons （diatoms and dinoflagellates） were higher than those of smaller groups （ prasinophytes, chlorophytes and cyanobacteria）. Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons （December and February）.
文摘The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.
基金supported by Natural Science Foundation of China(No.U1612441,41673017)。
文摘Isotope dilution(ID)method has been widely applied to studies of elemental speciation and certification of the concentrations of geological reference materials.One of the key factors restricting the application of the ID method is the difficulty in identifying the optimal ratios of the isotope tracer(spike)to sample(S/N)and in estimating the error propagation.Here,using Se isotope as an example and employing a Monte Carlo method,we found that the optimal choice of spike and S/N are^(77)Se(spike)and 0.7,respectively.The S/N in the range from 0.1 to 4 can produce sufficiently low errors(<0.4%).Extending this method to other elements such as Cr,Fe,Ni,Sr,Cd and etc.,their optimal spike and S/N were also presented.According to the optimized parameters of Se,we determined the Se concentrations of geological reference materials(GRMs)by thiol cotton fiber(TCF)-hydride generation ID-MC-ICP-MS.The relative standard deviation is<5%,and the detection limit is reduced to0.1 ng/g.Most of the measured concentrations are consistent with those recommended by IGGE or reported previously.For some GRMs,discrepancies(e.g.6.90%for GSS-5)exist between our measurements and previous ones,which can be explained by the inhomogeneity of GRMs and/or the different digestion,purification and measurement methods among laboratories.
