In this work, Mn doped AIZS/ZnS (Mn:AIZS/ZnS) nanocrystals (NCs) have
been synthesized in an approach using heat-up and drop-wise addition of
precursors. On the basis of the characterization of these doped NCs on their
optical properties and materials, it is found that: (1) as more Mn atoms are
doped into NCs, the doped NCs present photoluminescence (PL) red-shift and
quantum yield quenching; (2) the doped NCs possess a short PL lifetime in tens
of microseconds and a long PL lifetime in hundreds of microseconds, and the
short lived PL is more dominant than the long lived one; and (3) the doped NCs
present a reversible PL thermal quenching in a range from room temperature to
170°C. Possible PL mechanisms of these NCs were discussed by analyzing
their time-resolved PL spectra and thermal stability.
In this paper, an ultrafast steady-state genetic algorithm processor (GAP) is presented. Due to the heavy computational load of genetic algorithms (GAs), they usually take a long time to find optimum solutions. Hardware implementation is a significant approach to overcome the problem by speeding up the GAs procedure. Hence, we designed a digital CMOS implementation of GA in [Formula: see text] process. The proposed processor is not bounded to a specific application. Indeed, it is a general-purpose processor, which is capable of performing optimization in any possible application. Utilizing speed-boosting techniques, such as pipeline scheme, parallel coarse-grained processing, parallel fitness computation, parallel selection of parents, dual-population scheme, and support for pipelined fitness computation, the proposed processor significantly reduces the processing time. Furthermore, by relying on a built-in discard operator the proposed hardware may be used in constrained problems that are very common in control applications. In the proposed design, a large search space is achievable through the bit string length extension of individuals in the genetic population by connecting the 32-bit GAPs. In addition, the proposed processor supports parallel processing, in which the GAs procedure can be run on several connected processors simultaneously.
In this work, Mn-doped AZIS/ZnS NCs were prepared using a nucleation doping approach with the tuning of Mn and Ag levels in their synthesis. The optical properties of Mn:AZIS/ZnS NCs are found to be significantly affected by Ag and Mn levels. Specifically, more Ag and Mn atoms in Mn:AZIS/ZnS NCs cause their fluorescence red-shift, and as the Ag or Mn level reaches a high threshold, the fluorescence lifetime of Mn:AZIS/ZnS NC has a significant drop. The reasons for the effects of Mn and Ag levels on NC optical properties were explored and discussed. Through this study, it is also found that with certain Ag and Mn levels in synthesis, some Mn:AZIS/ZnS NCs present optimal optical properties including high brightness (QY > 40%), long fluorescence lifetime (> 1.2 ms), low energy for excitation (excitable at 405 nm), and no reabsorption. The feasibility of the optimized NCs for time-gated fluorescence measurement using a portable/compact instrument was further demonstrated, which indicates the application potential of the NCs in time-gated biosensing including point-of-care testing. Notably, this study also discloses that Mn:AZIS/ZnS NCs with different lifetimes can be achieved by tuning Mn and Ag levels in synthesis, which may further broaden the applications of Mn:AZIS/ZnS NCs in multiplexing detection/measurement.
In this work, a time-gated immunoassay platform using low-energy excitable and fluorescence long-lived Mn:AgZnInS/ZnS nanocrystals as signal transducers was developed and applied to the detection of the capsular polysaccharide (CPS) of Burkholderia pseudomallei, a Gram-negative bacterium that is the causative agent of melioidosis. CPS is a high molecular weight antigen displayed and is shed from the outer membrane of B. pseudomallei. The immunoassay using the time-gated platform presents a limit of detection at around 23 pg/ml when CPS is spiked in human serum.
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