One of the most recent techniques for the diagnosis of EP （early pregnancy） in cattle on the farm is B-mode ultrasonography. Under field conditions, acceptable results may be achieved with ultrasonography from days ...One of the most recent techniques for the diagnosis of EP （early pregnancy） in cattle on the farm is B-mode ultrasonography. Under field conditions, acceptable results may be achieved with ultrasonography from days 25 to 30 post-AI. The reliability of the test greatly depends on the frequency of the transducer used, the skill of the examiner, the criterion used for a positive PD （pregnancy diagnosis） and the position of the uterus in the pelvic inlet. Pregnancy protein assays （PAG, PSPB） may provide an alternative method to ultrasonography for determining EP or LEM/EFM （late embryonic/early foetal mortality） in the cow. Although early pregnancy factor is the earliest specific indicator for fertilization, its detection is entirely dependend on the use of the RIT （rosette inhibition test）, therefore its use in the field needs further inventions. Preventive pharmaceutical treatments with hCG （human chorionic gonadotropin）, GnRH （gonadotropin realising hormone）, PRID （progesterone-releasing intravaginal device） or CIDR （controlled internal drug release） inserts at different time periods at or post-AI may have some benefit in decreasing PL （pregnancy loss）, however further examinations are warranted to determine how and when these treatments may influence PL in the field.展开更多
Sediments in many rivers and lakes are subjected to resuspension due to a combination of hydrodynamics. However, the roles of contaminant-contained dissolved and particulate sediments during the resuspension release a...Sediments in many rivers and lakes are subjected to resuspension due to a combination of hydrodynamics. However, the roles of contaminant-contained dissolved and particulate sediments during the resuspension release are rarely studied. This study focuses on the release quantity of contaminants in both water phase and solid phase. Conservative tracer （NaC1） and reactive tracer （Phosphorus） were respectively added to cohesive fine-grained sediments and non-cohesive coarse-grained sediments. A range of typical shear stress was conducted to characterize the time-depended release of contaminants in a laboratory flume. When the sediment started to move, the concentration of contaminant in the overlying water increased with the bed shear stress, but the dissolved contaminants responded faster than the particulate ones. The observed contaminant release process can be divided into three main stages： the initial two hours fast mixing： the release contribution of pore water could reach up to 75%; the middle 4-6 h adsorption： the partitioning coefficient of contaminant between water phase and solid phase decreased over the time, and the adsorption of contaminates from resuspended sediment dominated the negative release; the last equilibrium stage： the desorption and adsorption reached equilibrium, and the reactive contaminant made an impact on the water quality in the solid phase. The existing formulas to evaluate the release flux are far from practice meaning as the sediment contaminants undergo a very complex release process.展开更多
文摘One of the most recent techniques for the diagnosis of EP （early pregnancy） in cattle on the farm is B-mode ultrasonography. Under field conditions, acceptable results may be achieved with ultrasonography from days 25 to 30 post-AI. The reliability of the test greatly depends on the frequency of the transducer used, the skill of the examiner, the criterion used for a positive PD （pregnancy diagnosis） and the position of the uterus in the pelvic inlet. Pregnancy protein assays （PAG, PSPB） may provide an alternative method to ultrasonography for determining EP or LEM/EFM （late embryonic/early foetal mortality） in the cow. Although early pregnancy factor is the earliest specific indicator for fertilization, its detection is entirely dependend on the use of the RIT （rosette inhibition test）, therefore its use in the field needs further inventions. Preventive pharmaceutical treatments with hCG （human chorionic gonadotropin）, GnRH （gonadotropin realising hormone）, PRID （progesterone-releasing intravaginal device） or CIDR （controlled internal drug release） inserts at different time periods at or post-AI may have some benefit in decreasing PL （pregnancy loss）, however further examinations are warranted to determine how and when these treatments may influence PL in the field.
基金supported by the National Natural Science Foundation of China(Grant No.10972134)the State Key Program of National Natural Science of China(Grant No.11032007)
文摘Sediments in many rivers and lakes are subjected to resuspension due to a combination of hydrodynamics. However, the roles of contaminant-contained dissolved and particulate sediments during the resuspension release are rarely studied. This study focuses on the release quantity of contaminants in both water phase and solid phase. Conservative tracer （NaC1） and reactive tracer （Phosphorus） were respectively added to cohesive fine-grained sediments and non-cohesive coarse-grained sediments. A range of typical shear stress was conducted to characterize the time-depended release of contaminants in a laboratory flume. When the sediment started to move, the concentration of contaminant in the overlying water increased with the bed shear stress, but the dissolved contaminants responded faster than the particulate ones. The observed contaminant release process can be divided into three main stages： the initial two hours fast mixing： the release contribution of pore water could reach up to 75%; the middle 4-6 h adsorption： the partitioning coefficient of contaminant between water phase and solid phase decreased over the time, and the adsorption of contaminates from resuspended sediment dominated the negative release; the last equilibrium stage： the desorption and adsorption reached equilibrium, and the reactive contaminant made an impact on the water quality in the solid phase. The existing formulas to evaluate the release flux are far from practice meaning as the sediment contaminants undergo a very complex release process.
