Three-order enhanced upconversion luminescence from upconversion nanoparticles is suggested by way of a promising platform utilizing a disordered array of plasmonic metal nanoparticles. Its application toward highly sensitive NIR photodetectors is discussed.
We report an experimental study on the highly enhanced upconversion luminescence (UCL) of β-NaYF4:Yb(3+)/Er(3+) nanocrystals (NCs) in a plasmonic architecture. For the architecture, we designed a thin film device composed of a thin layer of NCs capped with an upper layer of a plasmonic nanodome array (pNDA) and lower substrate of a back reflector (BR). Compared to the UCL intensity observed in a glass reference substrate, the designed plasmonic architecture exhibits distinctively strong luminescence enhanced by up to 800-fold. The intensity considerably exceeds the previously reported luminescence intensity regardless of the excitation power. We elucidated a mechanism explaining the large UCL enhancement, which quantitatively analyzes the combination of plasmonic effects as well as multiple large scattering. More importantly, we provided a detailed analysis of the Ag NDA-derived and BR-assisted plasmonic effects that contribute to an increase in the radiative decay rate and an enhancement of the absorption of incident light. The present study is expected to be beneficial for designing a thin film-based plasmonic structure with a randomized metal nanostructure for high-efficiency photovoltaic devices and infrared detectors.
The emergence of livestock-associated (LA)-methicillin-resistant Staphylococcus aureus (MRSA) in livestock animal has become a significant zoonotic concern. In the present study, we investigated nationwide prevalence of LA-MRSA across pork production chain including pig farms, slaughterhouses, and retail markets. A total of 40 MRSA strains were isolated during the investigation and the overall prevalence of MRSA was 3.4% (n = 37), 0.6% (n = 2), and 0.4% (n = 1) in pig farms, slaughterhouses, and retail markets, respectively. Multilocus sequence typing analyses revealed that the 2 most significant clonal lineages in pork production chain in Korea were ST398 (n = 25) and ST541 (n = 6). All of the 40 MRSA isolates were further characterized to investigate key genotypic and phenotypic correlates associated with the emergence and spread of clonal complex 398 (CC398; ST398, and ST541) LA-MRSA. Although the prevalence of swine-associated MRSA was still relatively low and mostly restricted to pig farms, multidrug-resistant CC398 LA-MRSA isolates with new spa types (t18102 and t18103) were identified as a major clonal lineage. The CC398 LA-MRSA strains tended to exhibit increased levels of multiple drug resistance (MDR) phenotype compared with non-CC398 MRSA strains. Of note, in comparison with non-CC398 MRSA isolates, CC398 LA-MRSA isolates exhibited significantly enhanced tetracycline (TET) and zinc resistance. These findings suggested that co-selection pressure associated with MDR phenotype, especially TET resistance, and zinc resistance may have played a significant role in the emergence and persistence of CC398 LA-MRSA in pig farms in Korea.
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