[Research Progress in the Application of Terahertz Spectroscopy and Imaging Technology in Stomatology].

Terahertz waves, the electromagnetic waves in the range of 0.1 to 10 THz, has the advantages of being damage-free, causing no ionizing radiation injury, and being capable of recognizing the fingerprint spectrum of molecular characteristics, thus holding encouraging prospects for wide applications in the field of biomedicine. Terahertz spectrum can be used to identify and characterize biological structures of different levels, from biomolecules such as proteins to cells and tissues, through the spectral signals and/or restored images of the samples. Herein, we summarized the current stomatogical application of and research progress in terahertz spectroscopy and imaging in dentistry, reported the latest research findings, strengths and limitations from three perspectives, tooth anatomical structure, the extent of caries progression, and oral soft tissue, and suggested possible directions for future exploration.

[Study on the influence of light intensity on near-infrared diffuse reflectance spectra of pear soluble solids content].

The objective of the present research was to study the influence of four kinds of light intensity of near-infrared diffuse reflectance spectra on the determination of pear soluble solids content. Qualitative analysis of the four spectra showed that the differences between them were too slight to find. After further analysis by principal component regression (PCR), stepwise multiple linear regression (SMLR) and partial least squares regression (PLSR) as well as comparisons among them, the results of PCR model and SMLR models which had low correlation coefficients (r) were worse than those of PLSR model. The model based on PLSR was further optimized by the second order derivative pretreatments of the spectra, and its correlation coefficients ranged from 0.947 to 0.970. The relative coefficients in PLSR model based on spectra from four sets were 0.958. The results indicate that light intensity has little influence on the determination of pear soluble solids content based on near-infrared diffuse reflection spectra.