Investigation of Silicon Core-Based Fiber Bragg Grating for Simultaneous Detection of Temperature and Refractive Index.

In this article, we theoretically designed and simulated a silicon core fiber for the simultaneous detection of temperature and refractive index. We first discussed the parameters of the silicon core fiber for near single-mode operation. Second, we designed and simulated a silicon core-based fiber Bragg grating and applied it for simultaneous sensing of temperature and environmental refractive index. The sensitivities for the temperature and refractive index were 80.5 pm/°C and 208.76 dB/RIU, respectively, within a temperature range of 0 to 50 °C and a refractive index range of 1.0 to 1.4. The proposed fiber sensor head can provide a method with simple structure and high sensitivity for various sensing targets.

[Effects on the shear bond strength of orthodontic brackets with different concentration of fluorided etching fluid].

OBJECTIVE: This study was to find out the most suitable concentration of added NaF to enough bonding strength of brackets. METHODS: Sixty-four teeth were randomly divided into A, B, C and the control group. NaF of four different concentrations (1.23%, 2%, 3% and 0%) was added into 35% phosphoric acid. The four group teeth were etched with four kinds of fluoride etching fluid respectively and were bonded with brackets. Four specimens in each group were selected by turns after 1, 4, 12 and 24 weeks of bonding. The shear bond strength of the teeth were tested, and the adhesive residual index (ARI) of bonding interface were recorded. RESULTS: The shear bond strength at four test time in each group was no significant (P > 0.05). There was statistical difference of the shear bond strength between four groups (P < 0.05), and group C was lower than the other groups. The ARI was no statistical difference between four groups. CONCLUSION: The effects of etching and bonding had no significant changes when the concentration of added NaF was no more than 2%. The shear bond strength decreased while the concentration of NaF was higher than 3%.

[Effect of fluorided etching fluid on the shear bond strength and the deposition on the surface of enamel.].

PURPOSE: The aim of this study was to find the best concentration of fluorided etching acid in the dental clinic which had both the best shear bond strength and the maximal anti-caries effect. METHODS: 84 extracted human premolars were divided into four groups of 21 teeth each. The enamel of each group was conditioned with 35% phosphoric acid containing 0%, 1.23%, 2%, 3% NaF. The shear bond strength was tested by bond strength machine and the enamel morphology was observed by scanning electron microscopy at once, 1 week, 4 weeks, 12 weeks, 24 weeks after etching. The shear bond strength was statistically analyzed by SPSS10.0 software. RESULTS: The shear bond strength of the group whose acid containing 3% NaF was less than the others significantly (P<0.05); and there was no significant difference among the other groups (P>0.05). The amount of the deposition on the surface of enamel after etching was increased with the time after etching and the concentration of NaF increasing. CONCLUSIONS: 2% NaF added to 35% phosphoric acid has both the best bond strength and the best effect of preventing enamel from caries.