RESUMO
The critical structural parameters are optimized and studied using the numerical simulation method to improve the resolution and stability of the Micro-Thrust Measurement Platform (MTMP). Under two different ground random vibration environments, the parameters, such as pivot thickness, pendulum rod length, and pivot structure, are focused on analyzing the influence of the system's resolution and stability. The results show that when the thickness of the pivot is 0.04 mm or 0.2 mm, and the pendulum rod length is 2 m, the effect of ground random vibration on the MTMP is minimized. At 0.1 mHz, it can reach 0.0057 µN/Hz. In the series double-pivot structure, an appropriate increase in the distance between the sheets can further optimize the above conclusions. The results and analysis within this study can provide support for the engineering design of the MTMP.
RESUMO
OBJECTIVE: To investigate the tumor proliferation and apoptosis changes after preoperative hepatic and regional arterial infusion chemotherapy (PHRAIC) after radical colorectal cancer resection. METHODS: Five hundred and nine patients with stage II or stage III colorectal cancer from June 2001 to June 2007 were randomly assigned to PHRAIC group (n = 256) or control group (n = 253, surgery alone). Tumor proliferation and apoptosis index were evaluated in tumor tissues of the control and PHRAIC group (pre and after intervention). The survival rates were also recorded in the two groups. RESULTS: There was no significant differences in sex, age, tumor location, tumor size, tumor stage, tumor differentiation and follow-up time for the two groups (P > 0.05). There was no significant differences in all the evaluation factors between the control group and PHRAIC group before intervention (P > 0.05). Before and after intervention for PHRAIC group: stage 3 necrosis rate were 3.1% and 22.7%, stage 4 necrosis rate were 0 and 13.5% (P < 0.05); label index of Ki67 were 48.6 +/- 17.1 and 38.4 +/- 13.3 (P < 0.05); expression rate of Bax, bcl-2 and survivin were 48.0% vs 77.0%, 75.0% vs 43.0%, 52.0% vs 31.6%, respectively (P < 0.05); apoptosis rate were 4.3% +/- 2.2% and 16.7% +/- 6.4%(P < 0.05). In the PHRAIC group, 42.1% +/- 11.2% of the cells in the tumor tissue were in S phase before intervention and the rate fell to 21.8% +/- 10.7% after intervention (P < 0.05); and G0-G1 phase rate of the group pre and post intervention were 35.1% +/- 12.1% and 57.1% +/- 18.1% (P < 0.05). All the patients were followed-up for a mean time of 42 +/- 14 months. For patients with stage III tumor in PHRAIC group and control group, the 5-year liver metastasis rate were 18.9% and 27.3% (P = 0.033), recurrence and metastasis rate were 26.3% and 38.0 (P = 0.024), overall survival rate were 81.0% and 60.4% (P = 0.011), median survival time were 45 and 40 months (P = 0.02); no significant differences of aforementioned factors was found in patients with stage II tumors between the two groups. CONCLUSION: The schedule of preoperative hepatic and regional arterial infusion chemotherapy before surgery can restrain proliferation, promote apoptosis and reduce liver metastasis and improve survival rate in stage III colorectal cancer.
