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THz spectrum of thiabendazole was determined with terahertz time domain
spectroscopy (THz-TDS) at room temperature, and comparison of its THz
spectrum with other two bactericides (thiophanate-methyl and benomyl) was
given. The solid-state density functional and isolated-molecule theories
were employed to interpret thiabendazole's THz spectrum with the PW91
density function and d and p polarization (DNP) basis set. In addition, we
applied THz-TDS to detect mixtures of thiabendazole and polyethylene with
different ratios, and compared the performances of four variable selection
methods for the prediction of thiabendazole content. The tested variable
selection algorithms included partial least squares (PLS), interval PLS
(iPLS), backward iPLS (biPLS) and moving window PLS (mwPLS). The PLS model
intervals were optimized according to the root mean square error of cross
validation (RMSECV) in the calibration set. The performances of models were
evaluated according to the root mean square error of prediction (RMSEP),
correlation coefficient (R) and relative error (E) in the prediction set.
In contrast with the other three methods, the mwPLS yielded the most
accurate result. The optimal mwPLS model was obtained with RMSEP=0.3629,
R=0.9995 and E=3.75%, and the investigation of mwPLS models with various
window sizes from 3 to 71 were examined.
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