The Effects of Content of Zr(NO3)4 on Formation and Characteristics of Micro-arc Oxidation Coatings Formed on ZAlSi12Cu2Mg1 Surface
The aims of this work are to prepare micro-arc oxidation coatings on the surface of ZAlSi12Cu2Mg1 aluminum alloy in Na2SiO3+NaOH+Na2EDTA electrolytes with and without Zr(NO3)4 and study their formation and characteristics. The phase constituent, surface microscopic morphology and cross-sectional morphology of the ceramic coatings were analyzed by XRD(X-ray diffraction), SEM(scanning electron microscope) and optical microscope. The thickness of the ceramic layer were measured by eddy current thickness gauge. The results show that the micro-arc oxidation films are mainly composed of mullite, α-Al2O3 and γ-Al2O3, it provides excellent adhesion with the substrate. With the content of Zr(NO3)4 in electrolyte varies from 0g/L to 1.0g/L, the thickness of the ceramic coating increases sharply at first, but afterwards reduces slowly, and the maximum of thickness up to 202μm when content of Zr(NO3)4 is 0.5g/L. The addition of Zr(NO3)4 into the base electrolyte solution is helpful in coatings formation and the coating formed in the solution containing 0.5g/L Zr(NO3)4 exhibits the best comprehensive features.
Effects of Process Parameters on Thickness and Hardness of Micro-Arc Oxidation Aluminum Oxide Ceramic Coating
The concept of oxidation power was introduced to reveal the action of energy during the micro-arc oxidation process. Thus micro-arc oxidation aluminum oxide coatings were prepared on LY12 Al alloy substrate at various process parameters using a pulse power supply. The thickness and hardness of the resulting ceramic coatings formed at fixed pulse width and frequency but varied duration and oxidation power were measured, and the changing tendencies of the thickness and hardness of the ceramic coatings with the process parameters were discussed. It was found that the hardness and thickness of the ceramic coatings tended to increase with increasing micro-arc oxidation power at fixed oxidation duration and area, while the thickness of the coating tended to increase with increasing micro-arc oxidation time and decrease with increasing workpiece area in case the other process parameters were kept constant.
Pharmacokinetics and Metabolism of 14C-Brivaracetam, a Novel SV2A Ligand, in Healthy Subjects
This study was designed to investigate the human absorption, disposition, and mass balance of 14C-brivaracetam, a novel high affinity SV2A ligand with potent anticonvulsant activity. Six healthy male subjects received a single p.o. dose of 14C-brivaracetam (150 mg, 82 μCi, or 3.03 MBq). Serial blood and complete urine and feces were collected until 144 h postdose. Expired air samples were obtained until 24 h. Brivaracetam was rapidly absorbed, with Cmax of 4 μg/ml occurring within 1.5 h of dosing. Unchanged brivaracetam amounted to 90% of the total plasma radioactivity, suggesting a modest first-pass effect. Plasma protein binding of radioactivity was low (17.5%). Urinary excretion exceeded 90% after 2 days, and the final mass balance reached 96.8% of the radioactivity in urine and 0.7% in feces. Only 8.6% of the radioactive dose was recovered in urine as unchanged brivaracetam, the remainder being identified as non–cytochrome P450 (P450)- and P450-dependent biotransformation products resulting from hydrolysis of the amide moiety (M9, 34.2%), hydroxylation of the n-propyl side chain (M1b, 15.9%), and a combination of these two pathways leading to the hydroxy acid (M4b, 15.2%). Minor amounts of taurine and glucuronic acid conjugates and other oxidized derivatives were also identified. Brivaracetam is completely absorbed, is weakly bound to plasma proteins, extensively biotransformed through several metabolic pathways, and eliminated renally.