Zhen Xu, Guijiang Diao, Yunqing Tang, Keyang Chen, Kaifan Lin, Anqiang He, Doug Fraser, Jing Li, Rei Chung, Q. Y. Li, D. Y. Li
High-entropy alloys (HEAs) and medium-entropy alloys (MEAs) have demonstrated many superior properties, including high strength, toughness, and thermal stability. Among MEAs, AlCrFeNi has received considerable attention due to its well-balanced mechanical properties and cost-effectiveness, making it a promising candidate for industrial applications. It is known that rare-earth elements can effectively enhance the oxidation resistance of alloys containing passive elements. In this study, AlCrFeNi MEAs with Y additions (0.5, 1.0, and 1.5 wt.%) were fabricated by arc melting. Microstructures of fabricated samples and their mechanical properties and resistance to air-jet sand erosion were investigated at both room temperature (20°C) and elevated temperature (700°C). For the sake of comparison, a commercial nickel-based Waspaloy superalloy was also evaluated. At both room and elevated temperatures, the AlCrFeNi MEA demonstrated high superiority over the widely used nickel-based superalloy. The Y additions increased the hardness and yield strength of the MEA, leading to improved erosion resistance at room temperature, which was more obvious at elevated temperatures, largely benefiting from the improved resistance to accelerated oxidation at elevated temperatures. The obtained information highlighted the beneficial effects of the minor Y additions in enhancing both the mechanical performance and high-temperature durability of the AlCrFeNi MEA, which would help extend the application of the MEA to higher temperatures.
Sylwia Ostrowska, Monika Szukowska, Shinik Kim, Yeonho Kim, Dariusz Wawrzyniak, Radosław Mrówczyński
In this paper, we present results of a study on the influence of different experimental conditions on drug release, for the two anticancer drugs: doxorubicin (DOX) and sorafenib (SO), from mesoporous silica nanoparticles coated with polydopamine (PDA) shell. We tested the drugs release from the carrier into buffers of different pH (4.5; 5.5; 7.5) and with the addition of H 2 O 2 or glutathione (GSH), while stirring the carriers in a flask or shaking them in a thermoblock, keeping the same time intervals, temperature and frequency. The obtained results and performed statistical analysis prove that the way the drug release tests are conducted has a significant influence on the efficiency of release of both drugs from the carrier. Thus, our results are of great importance for characterization of multimodal nanocarriers for biomedical application in terms of drug release and bring new knowledge for their methodological investigation.
Failure in the adhesion between hydroxyapatite and the metallic substrate in commercial biomaterials is one of the significant drawbacks in implantology. The demand for confident analytical methods to characterize these coatings is met through a rigorous research process. Fourier-transform infrared spectroscopy (FTIR) was chosen as the method to characterize hydroxyapatites. A meticulous data analysis from FTIR spectra was conducted, and an FTIR library was constructed from FTIR spectra of different types of hydroxyapatites, considering several chemical environments. The analytical procedure involved the registry of the spectra, localization of the leading absorption bands from the minima of the second derivative spectra, and reconstitution of the original spectra by curve deconvolution. The FTIR library was employed to analyze commercial surgical screws that failed in their use in different implants. Our methodology identified the structural reasons for such failure, caused by the selective removal of non-apatitic environments during adsorption onto the metallic implant. The method identifies the adhesion degree of the apatite coating on the implant before implantation in a biological organism, thereby preventing additional patient interventions and the associated costs.
Dye-sensitized solar cells comprise a fluorine doped tin oxide/titanium dioxide photoanode and a counter electrode of fluorine doped tin oxide covered with a catalytic material arranged in a sandwich configuration. Many processes take place inside a dye-sensitized solar cell. However, two involve the redox couple contained in the electrolyte solution: the dye regeneration and the recombination. While the first is a desired path, the latter impacts the power conversion efficiency of the cells, decreasing the measured values. In this work, iodine-based couples are evaluated using cyclic voltammetric measurements, and their behaviour is compared with two commercial electrolytes widely used in dye-sensitized solar cells, particularly when sensitized with natural dyes. Different experimental conditions, such as cell configurations and electrode materials, were adopted to understand the thermodynamics of the competitive electron transfer processes mentioned above.
