The catalytic performance of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand in the ring opening metathesis polymerization (ROMP) of fluorine containing monomers, exo-N-4-fluorophenyl-7-oxanorbornene-5,6-dicarboximide (FPhONDI) and exo-N-4-fluorophenyl-norbornene-5,6-dicarboximide (FPhNDI) was investigated. Pure monomers were subjected to ROMP with RuCl2(PCy3)2(CHPh) (I), RuCl2(PCy3)(H2IMes)(CHPh) (II), RuCl2(3-Br-py)2(PCy3)(CHPh) (III) and RuCl2(3-Br-py)2(H2IMes)(CHPh) (IV). The polymers were fully characterized using NMR, DSC, SEM and GPC. Catalysts I–IV displayed significant ROMP activity, allowing for the synthesis of the corresponding polymers with polydispersity indices (PDIs) in the range of 1.4–4.0. High molecular weight polymers (Mw up to 4.95 x105) were prepared in yields up to 90 %, depending on the initiator and monomer used. 相似文献
Chemically derived graphene (CDG) was prepared by hydrazine hydrate reduction of graphene oxide and used as support for palladium nanoparticles (Pd NPs) generated ex situ with controllable particle size and dispersion. The Pd NPs supported on CDG were well characterized by using a combination of advance analytical techniques and employed as catalyst in the dehydrogenation and hydrolysis of ammonia borane (AB) in organic solvents and aqueous solutions, respectively. Monodisperse Pd NPs of 4.5 nm were prepared from the reduction of palladium(II) acetylacetonate by tert-butylamine borane in the presence of oleylamine. They were readily impregnated on CDG which has BET surface area of 500 m2 g−1. Pd NPs retain their particle size dispersion and stability when supported on chemically derived graphene. The resulting materials are highly active and stable catalyst for the dehydrogenation and hydrolysis of AB. In addition to their high activity and stability, these Pd NPs are also reusable catalyst in both dehydrogenation and hydrolysis of AB preserving 85% and 95% of initial activity after 5th and 10th runs, respectively. 相似文献
Multimedia Tools and Applications - Image distortion effects, called noise, may occur due to various reasons such as image acquisition, transfer, and duplication. Image denoising is a preliminary... 相似文献
Jaya algorithm is one of the heuristic algorithms developed in recent years. The most important difference from other heuristic algorithms is that it updates its position according to its best and worst position. In addition to its simplicity, there is no algorithm-specific parameter. Because of these advantages, it has been preferred by researchers for problem-solving in the literature. In this study, the random walk phase of the original Jaya algorithm is developed and the Improved Jaya Algorithm (IJaya) is proposed. IJaya has been tested for success in eighteen classic benchmark test functions. Although the performance of the original Jaya algorithm has been tested at low dimensions in the literature, its success in large sizes has not been tested. In this study, IJaya's success in 10, 20, 30, 100, 500, and 1000 dimensions was examined. Also, the success of IJaya was tested in different population sizes. It has been proven that IJaya's performance has increased with the tests performed. Test results show that IJaya displays good performance and can be used as an alternative method for constrained optimization. In addition, three different engineering design problems were tested in different population sizes to demonstrate the achievements of Jaya and IJaya. According to the results, IJaya can be used as an optimization algorithm in the literature for continuous optimization and large-scale optimization problems.
During the past decade, gadolinium zirconate (Gd2Zr2O7, GZO) has attracted interest as an alternative material to partially yttria‐stabilized zirconia (YSZ) for thermal barrier coatings (TBCs). Despite the well‐known benefits of GZO, such as lower thermal conductivity and superior temperature capability compared to YSZ, processing of GZO via atmospheric plasma spraying (APS) still remains a challenge. Here, we report on APS experiments which were performed to investigate the influence of processing on GZO microstructure and lifetime of GZO/YSZ double‐layer TBCs. Different microstructures of GZO were produced and characterized in terms of porosity, stoichiometry, Young′s modulus, and their effects on the lifetime of YSZ/GZO double‐layer TBCs were discussed. Particle diagnostics were utilized for the optimization of the process parameters with respect to different microstructures of GZO and stoichiometry. It was found that both cumulative porosity of GZO and pore size distribution, which alter the Young′s modulus significantly, govern the lifetime of double layers. In addition, it was shown that the deviation in GZO stoichiometry due to gadolinia evaporation in the investigated range does not display any critical effect on lifetime. 相似文献