ABSTRACT
The reconstruction of the size, position, optical properties, and structure of the object in scattering media was realized with a chaotic fiber laser. The light from the chaotic fiber laser was split into two parts. One part was used as the detection signal to detect the object, and the other was used as the reference signal; then, the two signals were cross correlated. The attenuation of light in scattering media was attributed to scattering and absorption. The theoretical model of the peak value of cross correlation of the chaotic signals as projection data were established by the attenuation law, and the filtered back-projection algorithms were used to realize the image reconstruction. The mean squared error, the normalized mean squared error, the peak signal-to-noise ratio, and the structural similarity index of the reconstructed image were analyzed. The results show that the high resolution of the reconstructed image benefits from the high signal-to-noise ratio with the chaotic fiber laser based on a delta-like cross-correlation function.
ABSTRACT
Since the size of modulated crystal is limited with size in the conventional photo-elastic modulation system, it's a low spectrum resolution, so detection accuracy of gas concentration is not high. In order to improve the spectrum resolution of the system, an improved photo-elastic modulation system was designed. This method was carried out multiple reflection of incident light in the crystal. The optical path difference was increased by this method, so that a higher spectrum resolution was obtained. The entire system was constructed with the laser, photo-elastic modulator, polarizer, analyzer and photo-detector. Among them, a wedge angle (θ) was processed on modulation crystal. And a reflection film was plated on both sides; effective optical path length increase was implemented. Through the analysis the wedge angle (θ) was selected, and function on the optical path, the phase of modulation and the energy was calculated for the wedge angle. Ultimately, the appropriate wedge angle values were determined, and the corresponding optical path function expressions were given. In the experiments, the concentration of three common VOC gas was analyzed respectively. The concentration of sample gas was calibration by PTM400-VOC gas analyzer, and the results were compared with conventional photo-elastic modulation system. Experimental results show that gas concentration detection limit is reached to 0.010 mg·m-3 for improved photo-elastic modulation system, compared with conventional photo-elastic modulation system it's an order of magnitude or more. The gas concentration detection error was 3.4%, and it's also better than the traditional type. In summary, improved photo-elastic modulation system not only has the advantage of high static structural stability, but also a substantial increase in the spectrum resolution and detection accuracy of concentration.
ABSTRACT
The aim of this study was to determine whether caffeine enhanced radiosensitivity of normal liver tissue in a rat radiation-induced liver disease model. Buffalo rat McA-RH7777 hepatocellular cancer cells and BRL3A normal liver cells were irradiated, and cell cycle distribution and apoptosis rates were analyzed. A rat model of radiation-induced liver disease was established, rats were randomized into four groups: control; caffeine alone; irradiation (IR) alone; and caffeine plus IR (Caff + IR) group. Apoptosis rates in normal rat liver tissue after IR were evaluated by TUNEL staining and caspase-3 Western blot. Transaminase activity was measured and histopathological examination was done after IR. Caffeine abrogated IR-induced G2 phase arrest (Caff + IR vs. IR: 40.9 ± 4.0 vs. 60.7 ± 5.5%, at 12 h after IR) and increased apoptosis rates (Caff + IR vs. IR: 56.1 ± 6.8 vs. 35.5 ± 4.0%, at 72 h after IR) in McA-RH7777 cells, but did not affect IR-induced G2 phase arrest and apoptosis rates at any time point after IR in BRL3A cells. Caffeine did not enhance apoptosis, transaminase activity, or histopathological injury of normal rat liver tissue at any time points after IR. This study suggests that caffeine might not enhance radiosensitivity of normal liver tissue in vivo. In an earlier study, we reported that caffeine enhanced radiosensitivity of human hepatocellular cancer in a nude mice model. Together, these results offer feasibility of clinical application.
