A sensitive and rapid HPLC-DAD method for the determination of 3-hydroxy-1,2-dimethyl-4-pyridone and its distribution in rats

Purpose: To establish a sensitive and rapid method for the determination of the tissue distribution of 3-hydroxy-1,2-dimethyl-4-pyridone (L1) in vivo, and its plasma protein binding capacity.Methods: This study optimized a reverse-phase HPLC method for specific and sensitive determination of L1 as well as its plasma and tissue  distributions. The optimized method was used to determine the plasma protein-binding capacity of L1 in Wistar rats.Results: A rapid, sensitive and simple HPLC-DAD method was established for studying the plasma and tissue distribution of L1. Following TI  administration, its liver concentrations peaked at 60 min and 360min, followed 360 min later with peak level in the kidney (second highest). The L1 concentration was significantly lower after 360 min than after 60 min, and values of its mean binding to plasma proteins was 5.2 % at different L1 concentrations.Conclusion: These results indicate that L1 is a drug with rapid-absorption and rapid-elimination thath is distributed widely in vivo in rats. Moreover, the drug has a weak plasma protein-binding capacity. Keywords: 3-Hydroxy-1,2-dimethyl-4-pyridone, Distribution, Alzheimer’s disease, Therap

Analysis of longitudinal-vertical coupling vibration of four hub motors driven electric vehicle under unsteady condition

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfc and inverter switching frequency sideband harmonic k1fs±k2fc (fc = pn/60, fs is inverter switching frequency, k1 and k2 are positive integers, p is the number of pole pairs and n is motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3fc and 2fs. The main harmonic of vehicle body pitch angle acceleration is 2fs.</p

Prediction and Diagnosis for Unsteady Electromagnetic Vibroacoustic of IPMSMs for Electric Vehicles Considering Rotor Step Skewing and Current Harmonics

Purpose: This study provides a detailed investigation on the prediction and diagnosis of unsteady electromagnetic vibroacoustic performance of IPMSMs for electric vehicles under typical unsteady operating conditions with consideration of rotor step skewing and current harmonics. Methods: Firstly, the control model considering the influence of PWM carrier modulation and rotor step skewing is established. Based on this, the currents of the IPMSM under unsteady operating conditions (driving condition and feedback braking condition) are obtained. Accordingly, the currents calculated through the control model are used as the excitation source of electromagnetic finite element. Then, the electromagnetic vibroacoustic performance under unsteady operating conditions is calculated through electromagnetic force subsection mapping and acoustic transfer vector (ATV) method. Moreover, the conditions where resonance vibroacoustic occurs are diagnosed. Finally, the results of prediction and diagnosis are fully verified by experiments of multiple physical fields. Results and Conclusions: The amplitude errors between prediction results and test results are less than 3.2%. The influence of current harmonics on electromagnetic vibroacoustic can be predicted. The frequency range and speed range of predicted peak vibroacoustic are consistent with the experimental results. The rotor step skewing can be used to weaken the vibroacoustic amplitude of IPMSMs under typical unsteady conditions in the full speed range. This study provides guidance for prediction and diagnosis for electromagnetic vibroacoustic performance of IPMSMs under typical unsteady operating conditions.</p

Simultaneous Enhancement of Mechanical and Magnetic Properties in Extremely-Fine Nanograined Ni-P Alloys

Exploring structural effects that influence both the mechanics and magnetism in nanocrystalline materials, particularly extremely-fine nanograined ones with grain sizes down to several nanometers, is of high interest for developing multifunctional materials combining superior mechanical and magnetic performances. We found in this work that electrodeposited extremely-fine nanograined Ni-P alloys exhibit a significant enhancement of magnetization, simultaneously along with an increase in hardness, after low-temperature annealing. The relaxation of non-equilibrium structures, precipitation of the second phase and the segregation of P atoms to grain boundaries (GBs) during annealing have then been sequentially evidenced. By systematically comparing the variations in macroscopic and microstructural investigation results among several Ni-P alloys with different P contents, we suggest that the second phase has little effect on magnetization enhancement, and essentially both the structural relaxation and GB segregation can play important roles in hardening by governing GB stability, and in the improvement of magnetization by enhancing Ni&ndash;Ni atom exchange interactions

CEO Compensation around Corporate Spinoffs

Our study examines whether CEO compensation decreases in response to the reduction in firm size after a corporate spinoff. We find overall that CEO pay decreases subsequent to the spinoff, consistent with efficiency theory. However, the decrease is driven by the pay adjustment ac- companying CEO turnover around the spinoff. New CEOs hired around the spinoff have little bargaining power in regards to their compensation and thus we observe a decline in CEO compensation around these spinoff events. The compensation of those CEOs which span the spinoff event does not decrease, consistent with the notion of CEO entrenchment

Synthesis and Characterization of a Mg2+-Selective Fluorescent Probe

A new Mg2+-selective fluorescent probe P was synthesized and characterized. With optimal conditions, the proposed probe P showed good selectivity to Mg2+ compared to other common metal ions, and worked in a wide linear range of 5.0 × 10−7–6.0 × 10−6 M with a detection limit of 1.7 × 10−7 M Mg2+ in ethanol-water solution (9:1, v/v, 20 mM HEPES, pH = 10.0)