The quantitative structure property relationship (QSPR) for the photolysis half-life (t 1/2 ) of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) on spruce (Picea abies (L.) Karst.) needle surfaces under sunlight irradiation was investigated. Molecular distance-edge vector (MDEV) index was used as the structural descriptor of PCDD/Fs. The quantitative relationship between the MDEV index and log t 1/2 was modeled by using multivariable linear regression (MLR) and artificial neural network (ANN) respectively. Leave-one-out cross validation and external validation were carried out to assess the prediction ability of the developed models. For the MLR method, the prediction root mean square relative error (RMSRE) of leave-one-out cross validation and external validation is 3.47 and 4.25 respectively. For the ANN method, the prediction RMSRE of leave-one-out cross validation and external validation is 2.68 and 3.52 respectively. It is demonstrated that there is a quantitative relationship between the MDEV index and log t 1/2 of PCDD/Fs. Both MLR and ANN are practical for modeling this relationship. The developed MLR model and ANN model can be used to predict the log t 1/2 of PCDD/Fs. Thus, the log t 1/2 of each PCDD/F congener was predicted by using the developed models.

The authors have developed an avalanche transistor based pulser for use as a pockel cells driver and for gating a microchannel plate. The output voltage ranges from 1-4 kV to 50 ⍀, with fall times of 200-300 ps. The repetition rate is less than 1 kHz. The trig jitter is less than 100 ps. Trig delay is about 8 ns.

The application of dynamic time warping (DTW) to the correction of retention time shift in chromatographic fingerprints of Radix Puerariae thomsonii (RPT) was studied. The fingerprints of 27 RPT samples were established with their entire chromatograms. Because there is retention time shift in the obtained fingerprints, the quality of these samples cannot be correctly evaluated by applying similarity estimation and principal component analysis (PCA) to the unaligned fingerprints. Hence, the fingerprints were aligned by using DTW method. After alignment, the retention time shift was corrected satisfactorily and the quality of these RPT samples was correctly evaluated. It is demonstrated that DTW is a practical method for aligning the chromatographic fingerprints of RPT samples. The combination of similarity estimation, PCA and DTW is shown to be a promising method for evaluating the quality of herbal medicines.

A method which combines backward interval partial least squares and fluorescence spectroscopy was proposed to determine the enantiomeric composition of tryptophan.