In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOG...In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOGs）, three types of polarization-maintaining （PM） fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift （MWS） behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium （Ge） doped fibers and two germanium-phosphorus （Ge-P） codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.展开更多
Increasing evidence in both experimental and clinical studies suggests oxidative stress (OS) plays a major role in the pathogenesis of type 2 diabetes mellitus and its complications. In a physiological condition, appr...Increasing evidence in both experimental and clinical studies suggests oxidative stress (OS) plays a major role in the pathogenesis of type 2 diabetes mellitus and its complications. In a physiological condition, appropriate levels of ROS, generated either in restricted amounts or transient fashion, are required to promote physiological angiogenesis and homeostatic maintenance of healthy vasculature. Uncontrolled continuous ROS production will ultimately contribute to pathology and cause tissue damage. One of the most important proangiogenic factors is vascular endothelial growth factor (VEGF) which plays a key role in diabetic endothelial dysfunction, which ultimately leads to pathogenesis of vascular complications. As VEGF is released by activated platelets, hence platelet activation could be the source of VEGF in plasma samples. Increased platelet activity is emphasized to play a role in the development of vascular complications in T2DM patients and platelet volume, a marker of the platelet function and activation, is measured as mean platelet volume (MPV). Therefore, we aimed to investigate the association between plasma VEGF levels and MPV levels that may lead to vascular complications. A case-control study of one hundred patients with T2DM (n = 100) and thirty control subjects (n = 30) were screened from different areas of West Bengal. All procedures were done with the informed consent of participants. Elevated VEGF level was found in T2DM patients (526.8 ± 34.3 pg/ml) compared to healthy controls (317.9 ± 12.9 pg/ml) which was statistically significant. T2DM patients had higher MPV (12.5 ± 0.2 fl) compared to controls (11.4 ± 0.2 fl). Thus the present study showed a significant association between VEGF level in plasma and MPV indicating the severity of vascular complications. Hence, in conclusion, it suggested that VEGF levels along with MPV are a reliable biomarker for evaluating the development and progression of vascular complications.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 61007040)
文摘In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOGs）, three types of polarization-maintaining （PM） fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift （MWS） behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium （Ge） doped fibers and two germanium-phosphorus （Ge-P） codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.
文摘Increasing evidence in both experimental and clinical studies suggests oxidative stress (OS) plays a major role in the pathogenesis of type 2 diabetes mellitus and its complications. In a physiological condition, appropriate levels of ROS, generated either in restricted amounts or transient fashion, are required to promote physiological angiogenesis and homeostatic maintenance of healthy vasculature. Uncontrolled continuous ROS production will ultimately contribute to pathology and cause tissue damage. One of the most important proangiogenic factors is vascular endothelial growth factor (VEGF) which plays a key role in diabetic endothelial dysfunction, which ultimately leads to pathogenesis of vascular complications. As VEGF is released by activated platelets, hence platelet activation could be the source of VEGF in plasma samples. Increased platelet activity is emphasized to play a role in the development of vascular complications in T2DM patients and platelet volume, a marker of the platelet function and activation, is measured as mean platelet volume (MPV). Therefore, we aimed to investigate the association between plasma VEGF levels and MPV levels that may lead to vascular complications. A case-control study of one hundred patients with T2DM (n = 100) and thirty control subjects (n = 30) were screened from different areas of West Bengal. All procedures were done with the informed consent of participants. Elevated VEGF level was found in T2DM patients (526.8 ± 34.3 pg/ml) compared to healthy controls (317.9 ± 12.9 pg/ml) which was statistically significant. T2DM patients had higher MPV (12.5 ± 0.2 fl) compared to controls (11.4 ± 0.2 fl). Thus the present study showed a significant association between VEGF level in plasma and MPV indicating the severity of vascular complications. Hence, in conclusion, it suggested that VEGF levels along with MPV are a reliable biomarker for evaluating the development and progression of vascular complications.
