Degree of polymerization mapping Raman feature extraction of oil-paper insulation aging based on quadratic mutual information.

To assess the aging of oil-paper insulation, an accelerated aging experiment is executed. Raman spectroscopy, a nondestructive detection method with access to component identification and fault diagnosis, is used to analyze the aging of oil-paper insulation. Raman feature of oil-paper insulation aging with a close relationship with the degree of polymerization is obtained based on the concept of quadratic mutual information. By analyzing the relationship between the extracted feature and the degree of polymerization of samples at different aging degrees, the feasibility of reflecting the aging degree of oil-paper insulation is determined. By load analysis, the chemical correlation between the extracted feature and oil-paper insulation aging is clarified. For eight test samples, the prediction error of degree of polymerization based on Raman features is less than 50. These results show that the features extracted in this paper are helpful to realizing the Raman spectrum diagnosis of oil-paper insulation aging.

[The Detection of Raman Spectra on Dissolved Gas in Transformer Oil and Its Spectral Linear Model Analysis].

Raman spectroscopy gas detection technology which uses a single wavelength laser detection of gas samples without contact and loss is suitable for dissolved gas detection in oil-immersed transformers. Combined with the features of Raman spectral lines, the analysis of the detection mechanism in Raman spectroscopy technology has been made. Raman spectral lines have been presented in the expression of the convolution of Lorentz function and Gaussian function, which shows preferable Raman spectrum peak linear outline basic characteristics. In this paper, the basic features of the peak height, the peak position and the half peak width, are the main targets of peak searching, and the fundamental purpose of this paper is to obtain qualitative and quantitative analysis of the sample. Therefore, the experimental data of Raman spectroscopy is designed based on the comparison method to realize the automatic peak seeking model to achieve the detection target. Therefore, according to the automatic peak searching model based on the comparison method is designed to achieve the detection target. The simulation results of using peak searching model in the Voigt linear model show that spectrum peak height and peak position are in conformity with the theory in the test experiment. Based on the establishment of Raman spectroscopy detection platform aiming at the dissolved gas in transformer oil, the analysis of the experimental data show that the actual values of the half peak height and width are (8.7，11.5)(cm-1)in the Voigt linear model with deviations. Setting the value as 10.257 cm-1 to modify the parameter, then compared with the research results, it shows that the modified Voigt linear model and the peak searching model have better adaptability and practicability. Combined with the gas detection in the experimental platform in the experimental platform of Raman spectroscopy,detection of seven kinds of transformer fault characteristic gas and analysis of peak searching have been completed effectively. In terms of methane gas, the linear relationship among the unit gas content, Raman characteristic peak intensity and the area has been obtained, which has laid a foundation for the quantitative analysis of the dissolved gas in transformer oil.

Knowledge, attitudes and practices concerning self-medication with antibiotics among university students in western China.

OBJECTIVES: To evaluate the knowledge, attitude and behaviours of university students on the use of antibiotics. METHODS: A knowledge-attitude-practice questionnaire was developed and distributed to undergraduate students of Xi'an Jiaotong University, comprising 18 schools/colleges in Shaanxi Province, western China. Chi-square test and logistic regression analysis were applied to identify risk factors associated with self-medication with antibiotics. RESULTS: Of the 731 respondents (response rate = 73.1%), 294 (40.2%) had self-medicated with antibiotics in the past 6 months. Most of the antibiotics (59.2%) for self-medication were purchased without prescription in retail pharmacies. The median score of students' knowledge about antibiotics was 4 (IQR: 3-6) of a maximum possible score of 10. Students had moderately accurate beliefs towards antibiotics. More than half of the students (56.5%) were storing antibiotics frequently. During self-medication, 16.7% of students claimed to have experienced adverse reactions, and 30.6% had used antibiotics to prevent common colds. The majority preferred to use broad-spectrum antibiotics, and nearly half preferred intravenous antibiotics. Over 44% of students had changed antibiotic dosage, and 36.5% had switched to another antibiotic during the treatment course. Logistic regression analysis identified college and home town as independent risk factors for self-medication with antibiotics (P < 0.01). CONCLUSIONS: Undergraduate students had inadequate knowledge, moderately accurate beliefs and inappropriate practices concerning antibiotics, and a high rate of self-medication. This highlights the need for focused educational intervention and stricter governmental regulation concerning antibiotic use and sale in retail pharmacies.

Small diameter vascular grafts: progress on electrospinning matrix/stem cell blending approach.

The exploration of the next-generation small diameter vascular grafts (SDVGs) will never stop until they possess high biocompatibility and patency comparable to autologous native blood vessels. Integrating biocompatible electrospinning (ES) matrices with highly bioactive stem cells (SCs) provides a rational and promising solution. ES is a simple, fast, flexible and universal technology to prepare extracellular matrix-like fibrous scaffolds in large scale, while SCs are valuable, multifunctional and favorable seed cells with special characteristics for the emerging field of cell therapy and regenerative medicine. Both ES matrices and SCs are advanced resources with medical application prospects, and the combination may share their advantages to drive the overcoming of the long-lasting hurdles in SDVG field. In this review, the advances on SDVGs based on ES matrices and SCs (including pluripotent SCs, multipotent SCs, and unipotent SCs) are sorted out, and current challenges and future prospects are discussed.