RESUMEN
The kinetics of benzophenone (BP) and its derivatives have been widely studied in different solvents by nanosecond laser flash photolysis as well as in the polymer matrix. With the development of functional polymer coating, BP, as well as other photocross-linkers, has been incorporated into the polymer backbone or side chain to form the covalent connection between polymer coatings and substrates, which can improve the mechanical and chemical stability of the coatings. In this work, a series of BP pendent zwitterionic copolymer kinetics were investigated using UV-vis for the first time. Because of the high hydrophilicity of the zwitterionic monomer, the influence of the polymer matrix's polarity on the cross-linking rate was observed. With a higher zwitterionic percentage in the copolymer, the polarity of the copolymer increases, BP reactivity decreases, and a hypothesis between the BP rate constant and partial coefficient log P was raised. Moreover, the thermal property is also an important factor affecting the BP reactivity. For polymers with high glass-transition temperature, the reactivity was not dominated by the chemical environment such as polarity, and the restricted segment movement reduces the cross-linking rate. Additionally, the ring substituents show similar effects to BP pendent copolymers as with small molecules. Electron-withdrawing groups help to stabilize the BP triplet radical and facilitate cross-linking, while electron-donating groups work conversely. Therefore, polarity, thermal properties, and substituents should be taken into consideration when designing BP-containing functional polymers.
RESUMEN
Gregarines are ubiquitous protozoan parasites that infect arthropods worldwide. More than 1,600 gregarine species have been described, but only a small percentage of invertebrates have been surveyed for these apicomplexan parasites. Adult dragonfly populations were surveyed for gregarines at two reservoirs in Texas, USA for 2 years. Gregarine prevalence and intensity were compared intraspecifically between host genders and reservoirs, among wing loads, and through time. Of the 29 dragonfly species collected, 41% hosted gregarines. Nine of these dragonfly species were previously undocumented as hosts. Among the commonly collected hosts, prevalence ranged from 18 to 52%. Parasites were aggregated among hosts and had a median intensity of five parasites per host. Gregarines were found only in hosts exceeding a minimum wing load, indicating that gregarines are likely not transferred from the naiad to adult during emergence. Prevalence and intensity increased during both years, suggesting that gregarine oocyst viability parallels increasing host population densities and may be short-lived. Prevalence and intensity also differed between dragonfly populations at two reservoirs. Regression analyses revealed that host species, host gender, month, and year were significant explanatory variables related to gregarine prevalence and intensity. Abundant information on odonate distributions, diversity, and mating activities makes dragonfly-gregarine systems excellent avenues for ecological, evolutionary, and parasitological research. Our results emphasize the importance of considering season, hosts, and habitat when studying gregarine-dragonfly ecology.
