The nonlinear vibration analysis related to viscoelastic damper is investigated for the new whole-spacecraft passive vibration isolator. The stepped sinusoidal sweep test is performed and the results reveal the nonlinearity of the system. The nonlinear motion equation is developed. The frequency response equation is derived by the method of harmonic balance. The experiment of various excitation levels are carried out contrasting with numerical simulations. The nonlinear influence factors to the vibration isolation system are argued and the identification results explain the effect parameters on the performance of the vibration isolator. The research work is of significant implications for the analysis and design of passive vibration isolator for a wide range of practical applications.
Graphene-bismuth oxide composite were fabricated through a facile hydrothermal method. The SEM, XRD, EDS, FTIR were performed to characterize the morphology, composition, structure and surface functional groups. It was found that the Bi2O3 evenly spread on the surface of graphene. What is interesting is that two kinds of bismuth oxide can be generate in an experiment. One is spherical Bi2O3 with a diameter of 1~2 μm, the other is about 40 nm particle-size growed on the surface of the graphene. The possible growth mechanism was discussed. Under UV-pulsed illumination, graphene-Bi2O3 composite electrodes can produce an extracurrent of about 52.92 μA/cm2 under 0.3 V bias voltage, this value is higher than the existing report, indicating potential applications in optoelectronic devices. The possible reasons are explained.
This paper deduced the stability condition of POGO vibration system using Routh criterion based on the dynamic model of POGO vibration system in liquid rockets. Aimed at the uncertainty of stability parameters of POGO vibration system in liquid rockets caused by the uncertainty of the system itself and all kinds of environment, it is used Monte Carlo method to make the simulate target practice analysis on the stability of POGO vibration system in liquid rockets. The results show that the stable frequency of POGO vibration system in liquid rockets has the tendency that first increasing and then decreasing as targeting times increases, but the change is very small. It provides a theory reference for POGO vibration abatement in liquid rockets.
Abstract. Serum biomarkers are of diagnostic value and can be used for follow-up and prognostic factors. However, serum protein biomarkers show limited diagnostic sensitivity and specificity in stand-alone assays breast cancer because their levels refect tumor burden. In this study, we reviewed the levels of CA15-3, TSGF, CA125 and CEA both in nipple discharge and serum in 179 cases of breast lesions to assess the clinical value of nipple discharge and serum tumor markers in diagnosis, follow-up and prognostic in breast cancer. Our results indicate that the nipple discharge and serum levels of CA15-3, TSGF, CA125 and CEA in breast carcinomas patients were significantly higher than those in the benign disease (P<0.01). Aditionally, The levels of the four tumor markers in nipple discharge were significantly higher than in the serum (P<0.01). The levels of the four biomarkers in nipple discharge had positive correlation with histological grade, clinical stage, the Ki-67 index, expression of VEGF and HER-2/neu, lymphnode metastas and tumor recurrence (P<0.05, respectively), and negative correlation with the level of ER or PR (P<0.05, respectively). The sensitivity of the four serum tumor markes in combination was only 69.77%, in contrast, the combined detection both in discharge and serum was 97.67%, and the negative predictive value was 99.03%. The sensitivity of combined detection both in nipple discharge and serum were significantly higher than other detection (P<0.05). The four tumor markers in nipple discharge are as novel biomarker in dignosis and judging the prognosis of breast cancer. The dynamic combined detection of the four tumor markers both in nipple discharge and serum are helpful to the stratification of preoperative patients and benefit to better prewarning markers for monitoring their recurrence and metastasis of tumors in clinic, but cannot increase the sensitivity of judging the patients with early breast cancer.
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