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Multilayered thermal barrier coatings (TBC) are commonly used in systems exposed to extensive heat, such as jet engines or gas turbines. The testing of coatings’ performance is usually carried out using electric or gas furnaces. Concentrated solar power (CSP) could provide a cost-effective and environmentally friendly alternative using natural energy source. Moreover, it can also simulate material exposure in real applications, e.g., in solar power plant. In this study, the possibility of using concentrated solar power to test the performance of TBCs prepared by hybrid water/argon-stabilized plasma technology was studied for the first time. Testing procedure was carried out in three stages. In stage I, the procedure was optimized for multilayered TBC and then one selected condition was used in stage II and stage III also for hybrid TBCs. In service, TBC top-coat layer may be exposed also to so-called CMAS air-borne particles occurring in the atmosphere which may melt at elevated temperatures and penetrate the coating microstructure, inducing crystallographic and volumetric changes therein. Therefore, testing with the presence of CMAS particles was also included in this study to observe its influence on the coating microstructure under solar irradiation for potential environmental barrier coatings applications, e.g., solar power plants in desert areas. Changes in the coating microstructures were studied using SEM analysis and X-ray diffraction. The interaction of the coatings with melted CMAS particles was observed using EDS analysis. The results show that the CSP may be a suitable method for TBCs testing, if provided with several adjustments, especially regarding temperature control and measurement. In general, the tested TBCs withstood the CSP testing without significant morphological changes when tested without CMAS particles, while suffered from severe damage during the CSP testing with CMAS particles applied on the surface. [ABSTRACT FROM AUTHOR]

In the present work, novel organic-inorganic hybrids containing zirconium and phosphorus compounds were synthesized by using the sol-gel method, starting from zirconyl chloride hexahydrate (ZrOCl2·6H2O) and phenyl phosphonic acid (PPA). All the syntheses were performed at room temperature by using water as solvent. For some of the performed syntheses, alcohols with long hydrocarbon chain (n = 4–8) were added to the sol-gel process. They behave as nonionic surfactants due to their hydrophobic and hydrophilic groups, and they decrease the surface tension but without micelles formation, therefore without reaching CMC (critical micellar concentration). At a certain concentration, they will phase separate. This leads to the formation of a liquid/liquid interface. When the used alcohols were more hydrophobic, the obtained interface was more stable. This helped the synthesis and significantly changed its kinetics, as follows: in water, the chemical reaction was finished in 6 h, but when heptanol or octanol were added, the reaction time decreased to 3 h. [ABSTRACT FROM AUTHOR]

Natural products derived from medicinal plants have gained an important role in drug discovery due to their complex and abundant composition of secondary metabolites, with their structurally unique molecular components bearing a significant number of stereo-centers exhibiting high specificity linked to biological activity. Usually, the extraction process of natural products involves various techniques targeting separation of a specific class of compounds from a highly complex matrix. Aiding the process entails the use of well-defined and selective molecular extractants with distinctly configured structural attributes. Calixarenes conceivably belong to that class of molecules. They have been studied intensely over the years in an effort to develop new and highly selective receptors for biomolecules. These macrocycles, which display remarkable structural architectures and properties, could help usher a new approach in the efficient separation of specific classes of compounds from complex matrices in natural products. A simple and rapid such extraction method is presented herein, based on host-guest interaction(s) between a calixarene synthetic receptor, 4-tert-butyl-calix[6]arene, and natural biomolecular targets (amino acids and peptides) from Helleborus purpurascens and Viscum album. Advanced physicochemical methods (including GC-MS and chip-based nanoESI-MS analysis) suggest that the molecular structure and specifically the calixarene cavity size are closely linked to the nature of compounds separated. Incorporation of biomolecules and modification of the macrocyclic architecture during separation were probed and confirmed by scanning electronic microscopy and atomic force microscopy. The collective results project calixarene as a promising molecular extractant candidate, facilitating the selective separation of amino acids and peptides from natural products. [ABSTRACT FROM AUTHOR]

The present work describes the synthesis of novel hybrid materials by grafting process of phenyl phosphinic acid on different metal oxide surfaces (V2O5, ZrO2 and SnO2), by using a reactive milling process. Therefore, the syntheses took place in the solid phase, avoiding the presence of solvents. The grafting of the metal oxide surface is performed by using phenyl phosphinic acid as the coupling agent. After the syntheses in the solid phase were finished, the grafted materials were further characterized by FTIR, TGA, SEM and EDX methods. While phenyl phosphinic acid is water-soluble, the synthesized hybrids are insoluble in water. Moreover, from TGA results, it can be observed that the thermal stability increased significantly for the obtained hybrids in comparison with the starting reagents. In addition, the EDX data confirmed the presence of phosphorus, as well as the presence of the used metals (Zr, V and Sn). [ABSTRACT FROM AUTHOR]