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In this work, the graphene quantum dots (GQDs) based fluorescent sensors for detection of clen-buterol (CLB) using the fluorescence resonance energy transfer (FRET) effect were developed and characterized. In the sensors, GQDs played as donor meanwhile the conjugated molecule formed from N-1-naphthylethylen diamine (NED) and diazonium-CLB was the acceptor. A good overlapping between the acceptor’s UV-vis spectrum and donor’s PL spectrum was observed. The CLB detection limit of the sensors was found at the CLB concentration of 10−10 g/ml. A wide linearity relationship between the PL intensities of the sensors and the CLB concentrations in the range from 10−4 g/ml to 10−10 g/ml was observed. This report contributes to the design of GQDs based fluorescent sensor for detection of growth promoters.

Minimum Latency Problem (MLP) is a class of NP-hard combinatorial optimization problems which has many practical applications. In this paper, we propose a meta-heuristic algorithm which combines Tabu search (TS) and Variable Neighborhood Search (VNS) for the MLP. In the proposed algorithm, the TS is used to prevent the search from getting trapped into cycles, and guide the VNS to escape local optima. In a cooperative way, the VNS is employed to generate diverse neighborhoods for the TS. We introduce a novel neighborhoods' structure for the VNS, and indicate a sequential order to explore these neighborhoods such that the VNS can give best solutions. In order to reduce the time complexity of neighborhood search, we also propose a constant time algorithm for calculating the latency cost of each neighboring solution. Extensive numerical experiments and comparisons with best meta-heuristic algorithms proposed in the literature show that the proposed algorithm is highly competitive, providing new best solutions for some instances.

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