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To compare the Celect and Denali filters in terms of complex filter retrieval and indwelling complications after a 2-month indwelling time. In this prospective, randomized trial, 153 subjects were assessed for eligibility between May 2016 and July 2018. A total of 136 participants were randomly assigned to receive either Celect (n = 68) or Denali (n = 68) filter placement in the infrarenal inferior vena cava. Tilt angles at placement and retrieval and rates of overall filter retrieval, indwelling complication, and complex retrieval were compared. Of 136 participants (mean age, 62 ± 12.8 years, 55 male), 24 (17.6%) were lost to follow-up. The mean indwelling time of filter was 60.4 ± 7 days and there was no significant difference in the baseline characteristics between the two groups. Filter retrieval was successful in all participants (112/112, 100%). Significantly higher rates of filter tilt > 15° (n = 8) and strut penetration (n = 14) were found with the Celect filter than with the Denali filter (1 significant tilt and 1 penetration) (P = 0.033 and 0.001, respectively). No filter fractures were observed and there was no significant difference in tip embedment, filter fracture, filter migration, or mean fluoroscopy times. There were 3 cases of complex retrieval (1 for Denali vs. 2 for Celect, P = 0.500), for which the loop-snare technique was used. Denali filters demonstrated significantly lower rates of tilt angle > 15° and strut penetration. However, there was no significant difference in the complex filter retrieval rate between the Celect and Denali filters.

Electrophoretic painting (E-paint) was prepared on AZ31 Mg alloy samples pretreated in cerium conversion coating (CeCC) solutions with various ratios of ethanol and water mixture and its characteristics, adhesion and corrosion resistance were investigated. It was found that CeCC formed on AZ31 Mg alloy in a CeCC solution without ethanol was partly cracked structure and mainly consisted of Mg(OH)2/MgO, which exhibited weak adhesion with E-painting layer after water immersion test, and low corrosion resistance, as indicated by rapid formation of blisters and paint delamination during salt spray test. The addition of ethanol promoted the growth of a fine nano-crystalline CeO2 layer over the entire substrate surface. The E-paint on AZ31 pretreated in the CeCC solutions with addition of ethanol showed also improved corrosion resistance, as represented by the delayed time for paint delamination and blister formation. The E-paint layers on the CeCC layers formed in solutions containing 50–80 vol% ethanol showed stronger adhesion and better corrosion resistance than those formed on the samples treated in a non-ethanol containing CeCC solution.

A hybrid propulsion system composed of a homemade Polymer electrolyte fuel cell (PEFC) with a Lithium polymer (LiPo) battery in parallel connection was developed for Unmanned aerial vehicles (UAVs). The characteristics and performance of the system were evaluated considering its dynamic load responding capability and energy efficiency. A homemade PEFC stack composed of 36-unit cells and Balance of plant (BOP) was used to construct the fuel cell system directly connected to the propulsion system. Ten cells of a 3300-mAh 40C LiPo battery were combined with the PEFC system in parallel, and the LiPo battery was only switched on when high power was required for takeoff, acceleration and landing. The independent use of the homemade PEFC system and battery for the UAV showed a good load responding capability and a high fuel cell system efficiency of approximately 45%, which was obtained during cruising. The parasitic loss and the amount of unreacted hydrogen gas discharged outside of PEFC were nearly 3.91% and 0.89%, respectively. Results of the field test flights confirmed that the hybrid propulsion system based on the parallel connection of a PEFC system and a battery power is extremely effective in operating a UAV.

The present study reports the system configurations of a self-operated Polymer electrolyte fuel cell (PEFC) that is specially designed for dead-end operation of both pure hydrogen and oxygen gas lines, including its operation features and durability. The PEFC stack with 16 unit cells was constructed using homemade membrane electrode assemblies with 300 cm2 of apparent active area and bipolar plates. A self-operated PEFC system was developed using a homemade PEFC stack, balance of plant, and electric control unit for automatic fuel cell system operation. Performance parameters of the self-operated PEFC system, including fuel utilization, parasitic loss, released heat, purge loss, and efficiency of the PEMFC stack and system were evaluated during the automatic operation of the PEFC system. A Daily start-and-stop (DSS) test was also performed for one month to check the durability of the self-operated PEFC system. Electric efficiencies of the PEFC stack and system are approximately 60% and 49%, respectively, at an operating condition of 1.1 kW electric output; no performance degradation of the PEFC system was observed for a month during the DSS test.

In this work, a new method for detecting cathodic second-phase particles on the Mg alloy surface has been developed based on in situ observation of the blade-abraded surfaces of AZ31, AZ61, and 99.9 % pure Mg during the immersion in concentrated alkaline solutions. Continuous local gas evolutions were observed at certain points on the blade-abraded surface, and second-phase particles were found at the same positions, revealing the presence of cathodic particles at the gas evolution sites. The continuous local gas evolution reaction was found to be coupled with not only oxide formation reaction on the Mg matrix around the cathodic particles but also dissolution of Mg at the area within 2–3 μm distance from the cathodic particle. The gas evolution rate appeared to be proportional to the size of cathodic particles, and various cathodic particles containing Fe, Mn, Al, and/or Si were found to be present in the Mg alloys. Based upon the experimental results, it is concluded that the new method is simple, fast, and non-destructive, and it can be used to detect all the cathodic second-phase particles present on the entire surface of Mg alloys, irrespective of the sample shape and size.

Corrosion behavior and resistance of plasma electrolyte oxidation (PEO)-treated AZ31 Mg alloy were investigated by immersion and potentiodynamic polarization tests in 0.5 M NaCl solution in view of the PEO film thickness and sealing treatment of the PEO films in boiling water. The PEO films were formed using pulse current for various durations in 1 M NaOH + 0.5 M NaF solution. Filiform corrosion was observed during the immersion test while pitting corrosion occurred during the potentiodynamic polarization test, irrespective of sealing treatment of the PEO films. Corrosion resistance of AZ31 Mg alloy was improved remarkably by the formation of thicker PEO films and their sealing treatments.

Phosphating is one of the most widely used surface treatments of steels and aluminum due to its low-cost, easy mass production, good corrosion resistance and good adhesion with paint. Many researchers have tried to expand applications of the phosphating process, especially to magnesium alloys for automobiles and aerospace applications. Recently, the coatings on magnesium alloys by zinc phosphate conversion coatings (Zn3(PO4)2·4H2O) have been intensively studied. This paper reviews the state-of-the-art of phosphate conversion coatings developed for magnesium alloys, in terms of coating properties, phosphate conversion coatings processes and compositions of phosphating bath.