This Letter reports on an ultraweak intrinsic Fabry-Perot interferometer (IFPI) array fabricated by a femtosecond (fs) laser for distributed sensing applications. Ultralow reflectors (<-60 dB) were obtained. IFPIs with different physical lengths showed identical temperature sensitivity (-1.5 GHz/°C). A distributed temperature sensing test was conducted. No crosstalk between IFPI elements in the array was observed, implying the device's utility as a distributed sensing system. The possibility of using smaller bandwidths for sensor interrogation was experimentally proven. A small-scale temperature distribution test was conducted on a continuously cascaded ultraweak IFPI array, demonstrating its high spatial resolution. The temperature detection limit of this system was measured to be less than 0.0667°C.
This letter reports a fiber Bragg grating for distributed sensing applications fabricated using single-mode optical fiber and a femtosecond laser and interrogated in the terahertz range. A theoretical model of device behavior was derived, which agreed well with experimentally observed device behavior. In order to investigate the utility of terahertz fiber Bragg gratings (THz FBGs) as a sensing modality, temperature tests were conducted. The results demonstrated a sensitivity of -1.32 GHz/ºC and a detection resolution of less than 0.0017 ºC. A temperature distribution test was also conducted using a THz FBG, demonstrating its potential as a distributed sensing platform with high spatial resolution. The feasibility of interrogating THz FBGs using narrow interrogation bandwidths was also experimentally shown.
The resistance and immune escape of methicillin-resistant
Staphylococcus aureus
(MRSA) biofilms cause recalcitrant infections. Here, we design a targeting and synergizing cascade PDT with nutritional immunotherapy nanosystems (Arg-PCN@Gel) containing PCN-224 as PDT platform for providing reactive oxygen species (ROS), incorporating arginine (Arg) as nitric oxide (NO) donor to cascade with ROS to produce more lethal ONOO
−
and promote immune response, and coating with gelatin as targeting agent and persistent Arg provider. The nanosystems adhered to the autolysin of MRSA and inhibited Arg metabolism by down-regulating
icdA
and
icaA
. It suppressed polysaccharide intercellular adhesin and extracellular DNA synthesis to prevent biofilm formation. The NO broke mature biofilms and helped ROS and ONOO
−
penetrate into biofilms to inactivate internal MRSA. Arg-PCN@Gel drove Arg to enhance immunity via inducible NO synthase/NO axis and arginase/polyamine axis and achieve efficient target treatment in MRSA biofilm infections. The targeting and cascading PDT synergized with nutritional immunotherapy provide an effective promising strategy for biofilm-associated infections.
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