Comparison of properties of electromagnetic clutches with ferromagnetic powder and magnetorheological fluid for low frequency control signals
The article presents the results of laboratory tests for the two electromagnetic clutches of controllable: powder clutch and clutch fluid MR. The research was aimed at comparing the opportunities for coupling the power supply conditions in the low-frequency signals of 1 to 5 Hz. The system uses proprietary software written in Visual Studio C#. The program allows for controlled, laboratory power supply ATTEN PPS3205T-3S.
Micro-chain model of Magnetorheological fluids between two parallel disks
Digital holographic microscopy is presented in this study, which can measure the Magnetorheological fluids (MRF) in different volume percentage of particles and different magnetic field strengths. Based on the chain structure of magnetic particle under applied magnetic field, the relationships between shear yield stress, magnetic field, size and volume percentage of MRF in two parallel planes can be established. It has important theoretical significance for the design of optimized parameters and the manufacture of MRF. The results show the yield stress is directly proportional to the volume fraction and the magnetization of particles in the MRF. The theoretical model for yield stress of MRF is established and the variation tendency of shear strength in MRF with different material composition can be predicted by this theoretical model.
Influence of inducers and inhibitors on the metabolism in vitro and neurochemical effects in vivo of MDMA.
(S)-(+)- and (R)-(-)-3,4-methylenedioxymethamphetamine (MDMA) were metabolized in vitro by rat liver microsomes via N-demethylation to 3,4-methylenedioxyamphetamine (MDA). Whereas no difference was found in the biotransformation of the two enantiomers in the male rat or in the phenobarbital (PB) treated animals of either sex, more than twice as much MDA was formed from (S)-(+)- than from (R)-(-)-MDMA in the untreated female rat. Although 3-methylcholanthrene (3MC) pretreated rat liver microsomes were less active than those from the untreated rats of the same sex, they formed more MDA from (+)- than from (-)-MDMA. The enantioselective metabolism thus appears to be associated with the relative abundance of individual cytochrome P-450 isozymes. (S)-(+)- and (R)-(-)-MDMA.HCl (20 mg/kg) were about equipotent in depleting serotonin (5-HT) levels in the frontal cortex at 3 hrs and 1 wk following oral administration to female rats. Pretreatment of rats with SKF-525A attenuated and that with PB enhanced the 5-HT depleting potential of either isomer at 3 hrs. The 5-HT depleting potency of (+)-MDMA was significantly greater than that of its (-)-antipode at 3 hr in PB pretreated, but not in SKF-525A pretreated animals. The results suggest that the neurochemical effects of MDMA are caused by the formation of an active metabolite in vivo, and since both enantiomers were N-demethylated in vitro to approximately the same extent by PB pretreated rat liver microsomes, the active metabolite may be other than MDA.