[Identifying the characteristics of FTIR spectra of herba epimedii icariin via wavelet analysis and RBF neural network].

In the present paper, the authors extracted active components of herba epimedii and their important features using Fourier transform infrared spectroscopy (FTIR), correlation coefficient comparison, and multilevel wavelet analysis. The extracted features were then used to classify herba epimedii via radial basis function (RBF) neural network. There were altogether 250 samples of the medicine with various different types, including epimedium brevicornu Maxim., E. sagittatum (Sieb. et Zucc. ) Maxim, E. pubescens Maxim., E. koreanum Nakai and E. wushanense T. S. Ying. An important component of herba epimedii, herba epimedii icariin, has a special peak at 1 259 cm(-1) on the FTIR spectra obtained from the methanol extraction, which is consistent with the result obtained by traditional HPLC qualitative analysis. Therefore, this special peak can be used to determine if herba epimedii contains herba epimedii icariin. Furthermore, large variations in the spectrum caused by low content of icariin, weak absorption peaks and noise were successfully removed by applying correlation coefficient comparison and multilevel wavelet analysis, which significantly increased the quality of classification of RBF neural network. This paper creates a framework of fast identification of herba epimedii icariin in raw herba epimedii by FTIR spectra via wavelet analysis and RBF neural network.

An algorithm for thorough background subtraction from high-resolution LC/MS data: application for detection of glutathione-trapped reactive metabolites.

A control sample background-subtraction algorithm was developed for thorough subtraction of background and matrix-related signals in high-resolution, accurate mass liquid chromatography/mass spectrometry (LC/MS) data to reveal ions of interest in an analyte sample. This algorithm checked all ions in the control scans within a specified time window around the analyte scan for potential subtraction of ions found in that analyte scan. Applying this method, chromatographic fluctuations between runs were dealt with and background and matrix-related signals in the sample could be thoroughly subtracted. The effectiveness of this algorithm was demonstrated using four test compounds, clozapine, diclofenac, imipramine, and tacrine, to reveal glutathione (GSH)-trapped reactive metabolites after incubation with human liver microsomes supplemented with GSH (30 microM compound, 45-min incubation). Using this algorithm with a+/-1.0 min control scan time window, a+/-5 ppm mass error tolerance, and appropriate control samples, the GSH-trapped metabolites were revealed as the major peaks in the processed LC/MS profiles. Such profiles allowed for comprehensive and reliable identification of these metabolites without the need for any presumptions regarding their behavior or properties with respect to mass spectrometric detection. The algorithm was shown to provide superior results when compared to several commercially available background-subtraction algorithms. Many of the metabolites detected were doubly charged species which would be difficult to detect with traditional GSH adduct screening techniques, and thus, some of the adducts have not previously been reported in the literature.

Calcium phosphates produced by physical methods in the treatment of dentin hypersensitivity.

BACKGROUND: The aim of this paper is to study the properties of innovative materials based on defective calcium phosphates produced by physical methods in the therapy of dentin hypersensitivity. METHODS: In particular, the effects of gels, aqueous solutions and toothpastes containing the above mentioned materials on dentinal permeability measured as dentin hydraulic conductance have been studied. The calcium phosphates have been characterized by X-ray powder diffraction (Rietveld analysis) and Fourier transform infra-red analysis. In addition, scanning electron microscopy has been performed to study the surface of dentin and enamel after treatment with the phosphates. In particular sound occlusal dentin, sound cervical dentin, carious occlusal dentin, sound buccal enamel and carious buccal enamel have been observed. RESULTS: The results have shown that these biocompatible materials can be produced with chemical and physical characteristics very similar to dentin and/or enamel. By forming a protective layer inside and outside the dentin tubuli, the calcium phosphates significantly reduce the dentinal hypersensitivity. CONCLUSIONS: These phosphates seem to be a promising material for clinical application.