RESUMO
The phosphors Zn(1-x) Mo(1-y)Si(y)O4 : Eu(x)3+ (0.05 < or = x < or = 0.30, 0 < or = y < or = 0.09) were prepared by solid state reaction technique at 800 degrees C. The powder X-ray diffraction patterns of the samples show that the phosphors are of single phase and the doping Eu ion and Si ion have little influence on the host structure. The effects of flux and calcination temperature on the luminescent properties of the phosphors were investigated. The results showed that flux content has effects on the luminescent properties, and the optimized flux content and the best calcination temperature is 4% and 800 degrees C, respectively. The presence of the Na+ ion strengthens the photoluminescence intensity of the phosphors. The addition of Na+ ions balanced the charge in samples, enhanced the luminescence intensity of samples, and the luminescence intensity reached the maximum when the doping concentration of Na2 CO3 was 4 Wt%. The luminescent properties of Zn0.80 Mo(1-y)Si(y)O4 : Eu(0.20)3+ were studied by the excitation and emission spectra, and the influence of Eu3+ and Si4+ concentrations on the luminescent property was discussed. As the calcination temperature rises from 700 to 800 degrees C, the emission intensity increases due to the improvement of crystallinity. The excitation spectra consist of a broad band and a series of narrow lines, and the narrow lines are attributed to the intrinsic transition from 7FJ (J = 1-4) to 5DJ (J = 0, 1) of Eu3+. It was found that the PL emission intensity was enhanced with the increase in the Eu3+ doping ratio and reached a maximum value at x = 0.20. The result indicated that Zn(1-x)Mo(1-y)Si(y)O4 : Eu(x)3+ phosphors can be excited effectively at 393 and 464 nm light. The presence of the Si4+ ion strengthens the photoluminescence intensity of the phosphors and the strong red emission lines at 616 nm correspond to the forced electric dipole 5D0 --> F2 transitions on Eu3+. Compared with Y2O2S : 0.05 Eu3+, the obtained Zn0.80Mo0.97Si0.03O4 : Eu(0.20)3+ phosphor shows an enhanced red emission under 393 nm excitation and the emission intensity of Y2O2S : 0.05Eu3+ is only 50% of that of Zn0.80Mo0.97Si0.03O4 : Eu(0.20)3+. The optical properties suggest that Zn0.80Mo0.97Si0.03O4 : Eu(0.20)3+ is an efficient red emitting phosphor for light emitting diode (LED) applications.
RESUMO
OBJECTIVES: The purposes of this study are to investigate and analyze the status of reproductive tract infections (RTIs) in married women in rural western China, and to develop effective strategies for improving the ability of married women to prevent RTIs in this region. METHODS: We conducted in-depth interviews of 142 married women from four villages in three townships. Two questionnaires were used to gather data on married women's health care status, family income, knowledge about RTIs, relevant behaviors, and attitudes toward RTIs. Descriptive, parallel, and logistic regression analyses and the Chi-square test were applied to analyze the relationships between basic conditions and several influential factors. RESULTS: Over 80% of the respondents were of limited income and had with poor knowledge of and a lack of experience in preventing RTIs. Some 83.3% of the married women had experienced menstrual irregularities; 70.3% of those interviewed had experienced malodorous vaginal discharge with or without perineal itching. It was found that 80.7% of the interviewees did not have good personal hygiene habits in daily living regarding RTIs. It was found that the prevalence of RTIs was lower in women who had accurate information about RTIs. Most married women lacked basic knowledge of ways to prevent RTIs, and this, together with the limited support of the health care system and the absence of medical insurance schemes, was responsible for the observed high prevalence of RTIs. CONCLUSIONS: There is an urgent need to improve the capability of married women in rural China to prevent RTIs, and it is important to find effective ways to prevent these diseases. Three health promotion strategies are presently being implemented to prevent RTIs and to build capacity for disease prevention among married women in rural western China.
