RESUMO
Metal chalcogenide nanoparticles play a vital role in a wide range of applications and are typically stabilized by organic derivatives containing thiol, amine, or carboxyl moieties, where the nonconjugated particle-ligand interfaces limit the electronic interactions between the inorganic cores and organic ligands. Herein, a wet-chemistry method is developed for the facile preparation of stable platinum chalcogenide (S, Se) nanoparticles capped with acetylene derivatives (e.g., 4-ethylphenylacetylene, EPA). The formation of Pt-C≡ conjugated bonds at the nanoparticle interfaces, which is confirmed by optical and X-ray spectroscopic measurements, leads to markedly enhanced electronic interactions between the d electrons of the nanoparticle cores and π electrons of the acetylene moiety, in stark contrast to the mercapto-capped counterparts with only nonconjugated Pt-S- interfacial bonds, as manifested in spectroscopic measurements and density functional theory calculations. This study underscores the significance of conjugated anchoring linkages in the stabilization and functionalization of metal chalcogenides, a unique strategy for diverse applications.
RESUMO
Black Americans continue to have higher rates of HIV disease than other races/ethnicities. Conventional individual-level risk behaviors do not fully account for these racial/ethnic disparities. Sexual concurrency may help explain them. Respondent-driven sampling (RDS) was used to enroll 508 sexually active 18- to 30-year-old Black men and women in Durham, North Carolina in a cross-sectional survey on HIV-related topics. Consistent condom use was low for all participants, especially with steady partners. Concurrent partnerships in the past 6 months were relatively common for both men (38%) and women (25%). In general, men involved in concurrent relationships engaged in more risk behaviors than other men (e.g., inconsistent condom use and alcohol and drug use). A majority of concurrent partnerships involved steady partners. HIV-prevention programs should address the risks of concurrency and factors that discourage condom use, especially with steady partners with whom condom use is particularly low.