Toxic response of aquatic organisms to guide application of artemisinin sustained-release granule algaecide

In our previous study,we prepared the granules by embedding artemisinin into alginate-chitosan using microcapsule technology.These granules can release artemisinin sustainably and have a strong inhibitory effect on the growth of both single Microcystis aeruginosa and mixed algae.To safely and effectively use artemisinin sustained-release granules to control algal blooms,the ecotoxicity was studied by assessing their acute and chronic toxicity to Daphnia magna(D.magna)and Danio rerio(D.rerio),along with their antioxidant activities.The results showed that the 48-h median effective concentration(EC50)of pure artemisinin to D.magna was 24.54 mg/L and the 96-h median lethal concentration(LC50)of pure artemisinin to D.rerio was 68.08 mg/L.Both values were classified as intermediate toxicity according to the Organization for Economic Co-operation and Development(OECD).The optimal algae inhibitory concentration of artemisinin sustained-release granules(1 g/L)had low acute toxicity to both D.magna and D.rerio.The sustained-release granules had higher chronic toxicity to D.magna than to D.rerio.Partial indices of D.magna were inhibited by granules when the concentrations were larger than 0.1 g/L.Low granule concentration had an inductive effect on antioxidant enzyme activities in D.magna and D.rerio.With the increase of the exposure concentration and time,the enzyme activity presented a trend of first increasing and then decreasing,and the overall changes were significant.The change trend and range of enzyme activity indicated that the granules could cause serious oxidative stress to D.magna and D.rerio,and the changes were consistent with the results of toxicity experimentation.

Code design for run-length control in visible lightcommunication

Run-length limited(RLL)codes can facilitate reliable data transmission and provide flicker-free illumination in visible light communication(VLC)systems.We propose novel high-rate RLL codes,which can improve error performance and mitigate flicker.Two RLL coding schemes are developed by designing the finite-state machine to further enhance the coding gain by improving the minimum Hamming distance and using the state-splitting method to realize small state numbers.In our RLL code design,the construction of the codeword set is critical.This codeword set is designed considering the set-partitioning algorithm criterion.The flicker control and minimum Hamming distance of the various proposed RLL codes are described in detail,and the flicker performances of different codes are compared based on histograms.Simulations are conducted to evaluate the proposed RLL codes in on-off keying modulation VLC systems.Simulation results demonstrate that the proposed RLL codes achieve superior error performance to the existing RLL codes.