The acute and chronic toxic effects of bifenthrin on Daphnia magna were studied. The results showed that 24 h-EC 50 , 48 h-LC 50 and 96 h-LC 50 of bifenthrin on D. magna were 3.24, 12.40 and 1.40 μg/L r...The acute and chronic toxic effects of bifenthrin on Daphnia magna were studied. The results showed that 24 h-EC 50 , 48 h-LC 50 and 96 h-LC 50 of bifenthrin on D. magna were 3.24, 12.40 and 1.40 μg/L respectively. And the LOEC and NOEC of bifenthrin were 0.02 and 0.004 μg/L respectively. The recovery test of bifenthrin on Daphnia magna was presented. Daphnia magna(F 0 generation) were exposed during 21 d to different bifenthrin concentrations. Offspring(animals from the first and third brood: F 1(1st) and F 1(3rd), respectively) were transferred to a free pesticide medium during a 21 d recovery period. In this recovery study, survival, growth, reproduction(mean total young per female, onset of reproduction and number broods per female) and the intrinsic rate of natural increase (r) were assessed as parameters. Reproduction such as number of young per female as well as length was still reduced in F 1(1st) generation daphnids from parentals(F 0) exposed to the bifenthrin. However F 1(3rd) individuals from parentals exposed to pesticide concentrations were able to restore reproduction when a recovery period of 21 d was allowed, but the length of F 1(3rd) from parentals exposed to the 0.5 and 0.75 μg/L bifenthrin concentration was still significantly effected(P<0.05).展开更多
SMPU （shape memory polyurethane） non-ionomers and ionomers, synthesized with poly（c-caprolactone） （PCL）, 4, 4＇-diphenylmethane diisocyanate （MDI）, 1,4-butanediol （BDO）, dimethylolpropionic acid （DMPA） wer...SMPU （shape memory polyurethane） non-ionomers and ionomers, synthesized with poly（c-caprolactone） （PCL）, 4, 4＇-diphenylmethane diisocyanate （MDI）, 1,4-butanediol （BDO）, dimethylolpropionic acid （DMPA） were measured with cyclic tensile test and strain recovery test. The relations between the structure and shape memory effect of these two series were studied with respect to the ionic group content and the effect of neutralization. The resulting data indicate that, with the introduction of asymmetrical extender, the stress at 100% elongation is decreased for PU non-ionomer and ionomer series, especially lowered sharply for non-ionomer series; the fixation ratio of ionomer series is not affected obviously by the ionic group content; the total recovery ratio of ionomer series is decreased greatly. After sufficient relaxation time for samples stretched beforehand, the switching temperature is raised slightly, whereas the recovery ratio measured with strain recovery test method is lowered with increased DMPA content. The characterization with FT-IR, DSC, DMA elucidated that, the ordered hard domain of the two series is disrupted with the introduction of DMPA which causes more hard segments to dissolve in soft phase; ionic groups on hard segment enhance the cohesion between hard segments especially at high ionic group content and significantly facilitate the phase separation compared with the corresponding non-ionomer at moderate ionic group content.展开更多
In this paper,the hydrogeological parameters of a confined aquifer,such as transmissivity(T),storativity(S)and radius of influence(R),have been assessed using real groundwater level measurements recorded by a monitori...In this paper,the hydrogeological parameters of a confined aquifer,such as transmissivity(T),storativity(S)and radius of influence(R),have been assessed using real groundwater level measurements recorded by a monitoring network,consisting of automated municipal water supply boreholes at Nea Moudania aquifer,Chalkidiki,Greece.Particularly,the paper focused on the correlation between the drawdown and the constant flow rate during pumping time.So the Cooper-Jacob and the recovery test method were applied in order to delineate if turbulent head losses occur,as well as the impact of incorrect measurements of the radial distance(r)in the accuracy of estimating S values.The results show that a)the occurrence of a linear correlation between s and Q indicates a negligible turbulent head loss in the pumping wells and thus a reasonable flow rate usage,b)the validity of storativity values could be compromised if the r value is not accurately measured,and c)recovery test method can be used as an indicator of residual drawdown(s’)caused by previous pumping cycles,when the straight line intersecting the logarithmic t/t’axis has a value greater than 1.展开更多
Asphalt mixtures exhibit strong viscous properties under repetitive loads. This phenomenon can be simulated in creep and recovery tests. By applying the visco elastoplastic model proposed, data recorded in the tests ...Asphalt mixtures exhibit strong viscous properties under repetitive loads. This phenomenon can be simulated in creep and recovery tests. By applying the visco elastoplastic model proposed, data recorded in the tests are interpreted. It is emphasised that applicability of the visco elastoplastic model depends on the proper method of characterising parameters involved in the constitutive equations. Since two or more strain components of elasticity and viscosity coexist during the loading or unloading, a measuring system of two loggers is introduced to decouple these components. Test data are analysed in three steps as elastic, visco elastic and visco plastic evaluations, using the records collected at the moment of unloading, during the periods of recovery and creep respectively. Factors that may influence the accuracy of data analysis are also discussed.展开更多
The proton exchange membrane electrolysis cells(PEMECs)are electrochemical devices that efficiently produce high-purity hydrogen via electrical energy conversion,making them widely applicable in renewable energy stora...The proton exchange membrane electrolysis cells(PEMECs)are electrochemical devices that efficiently produce high-purity hydrogen via electrical energy conversion,making them widely applicable in renewable energy storage and hydrogen infrastructure development.However,the external sodium ion(Na^(+))contamination can severely damage the catalyst layer and membrane in PEMEC,causing significant performance degradation.Therefore,a segmented diagnostic platform for PEMEC is developed to analyze the poisoning effects of Na^(+)contamination on a large scale PEMEC under various operating conditions.The results demonstrate that during the cycle test,the Na^(+)poisoning process is defined as three distinct stages of initial,sustained and stable contamination stages.An increased Na^(+)concentration enhances the occupations of active sites on the catalyst layer,resulting in significant voltage spike,dynamic voltage fluctuations,non-uniformity distributions of current density and temperature.Both the low water flow rate and high operating temperature improve the chemical reaction and PEMEC performance at high current density.The deionized water flushing will dissolve Na^(+)on the catalyst layer surface and realize 2.17%decrease in voltage at 2.0 A cm^(-2) after three cycles.This study is beneficial to consolidate the understanding of poisoning effects of sodium ion contamination in PEMEC under various operating conditions,thereby overcoming the obstacles for commercial application of green hydrogen production technology.展开更多
文摘The acute and chronic toxic effects of bifenthrin on Daphnia magna were studied. The results showed that 24 h-EC 50 , 48 h-LC 50 and 96 h-LC 50 of bifenthrin on D. magna were 3.24, 12.40 and 1.40 μg/L respectively. And the LOEC and NOEC of bifenthrin were 0.02 and 0.004 μg/L respectively. The recovery test of bifenthrin on Daphnia magna was presented. Daphnia magna(F 0 generation) were exposed during 21 d to different bifenthrin concentrations. Offspring(animals from the first and third brood: F 1(1st) and F 1(3rd), respectively) were transferred to a free pesticide medium during a 21 d recovery period. In this recovery study, survival, growth, reproduction(mean total young per female, onset of reproduction and number broods per female) and the intrinsic rate of natural increase (r) were assessed as parameters. Reproduction such as number of young per female as well as length was still reduced in F 1(1st) generation daphnids from parentals(F 0) exposed to the bifenthrin. However F 1(3rd) individuals from parentals exposed to pesticide concentrations were able to restore reproduction when a recovery period of 21 d was allowed, but the length of F 1(3rd) from parentals exposed to the 0.5 and 0.75 μg/L bifenthrin concentration was still significantly effected(P<0.05).
基金This work was supported by Hong Kong ITF research project (No. ITS 098/02).
文摘SMPU （shape memory polyurethane） non-ionomers and ionomers, synthesized with poly（c-caprolactone） （PCL）, 4, 4＇-diphenylmethane diisocyanate （MDI）, 1,4-butanediol （BDO）, dimethylolpropionic acid （DMPA） were measured with cyclic tensile test and strain recovery test. The relations between the structure and shape memory effect of these two series were studied with respect to the ionic group content and the effect of neutralization. The resulting data indicate that, with the introduction of asymmetrical extender, the stress at 100% elongation is decreased for PU non-ionomer and ionomer series, especially lowered sharply for non-ionomer series; the fixation ratio of ionomer series is not affected obviously by the ionic group content; the total recovery ratio of ionomer series is decreased greatly. After sufficient relaxation time for samples stretched beforehand, the switching temperature is raised slightly, whereas the recovery ratio measured with strain recovery test method is lowered with increased DMPA content. The characterization with FT-IR, DSC, DMA elucidated that, the ordered hard domain of the two series is disrupted with the introduction of DMPA which causes more hard segments to dissolve in soft phase; ionic groups on hard segment enhance the cohesion between hard segments especially at high ionic group content and significantly facilitate the phase separation compared with the corresponding non-ionomer at moderate ionic group content.
文摘In this paper,the hydrogeological parameters of a confined aquifer,such as transmissivity(T),storativity(S)and radius of influence(R),have been assessed using real groundwater level measurements recorded by a monitoring network,consisting of automated municipal water supply boreholes at Nea Moudania aquifer,Chalkidiki,Greece.Particularly,the paper focused on the correlation between the drawdown and the constant flow rate during pumping time.So the Cooper-Jacob and the recovery test method were applied in order to delineate if turbulent head losses occur,as well as the impact of incorrect measurements of the radial distance(r)in the accuracy of estimating S values.The results show that a)the occurrence of a linear correlation between s and Q indicates a negligible turbulent head loss in the pumping wells and thus a reasonable flow rate usage,b)the validity of storativity values could be compromised if the r value is not accurately measured,and c)recovery test method can be used as an indicator of residual drawdown(s’)caused by previous pumping cycles,when the straight line intersecting the logarithmic t/t’axis has a value greater than 1.
文摘Asphalt mixtures exhibit strong viscous properties under repetitive loads. This phenomenon can be simulated in creep and recovery tests. By applying the visco elastoplastic model proposed, data recorded in the tests are interpreted. It is emphasised that applicability of the visco elastoplastic model depends on the proper method of characterising parameters involved in the constitutive equations. Since two or more strain components of elasticity and viscosity coexist during the loading or unloading, a measuring system of two loggers is introduced to decouple these components. Test data are analysed in three steps as elastic, visco elastic and visco plastic evaluations, using the records collected at the moment of unloading, during the periods of recovery and creep respectively. Factors that may influence the accuracy of data analysis are also discussed.
基金supported by the National Key R&D Program of China(Grant No.2023YFB4006301-1)the National Natural Science Foundation of China(Grant No.52476217 and Grant No.52311530069).
文摘The proton exchange membrane electrolysis cells(PEMECs)are electrochemical devices that efficiently produce high-purity hydrogen via electrical energy conversion,making them widely applicable in renewable energy storage and hydrogen infrastructure development.However,the external sodium ion(Na^(+))contamination can severely damage the catalyst layer and membrane in PEMEC,causing significant performance degradation.Therefore,a segmented diagnostic platform for PEMEC is developed to analyze the poisoning effects of Na^(+)contamination on a large scale PEMEC under various operating conditions.The results demonstrate that during the cycle test,the Na^(+)poisoning process is defined as three distinct stages of initial,sustained and stable contamination stages.An increased Na^(+)concentration enhances the occupations of active sites on the catalyst layer,resulting in significant voltage spike,dynamic voltage fluctuations,non-uniformity distributions of current density and temperature.Both the low water flow rate and high operating temperature improve the chemical reaction and PEMEC performance at high current density.The deionized water flushing will dissolve Na^(+)on the catalyst layer surface and realize 2.17%decrease in voltage at 2.0 A cm^(-2) after three cycles.This study is beneficial to consolidate the understanding of poisoning effects of sodium ion contamination in PEMEC under various operating conditions,thereby overcoming the obstacles for commercial application of green hydrogen production technology.
