术前免疫炎症指数与胃癌患者预后关系的研究

目的:探讨术前免疫炎症指数(systemic immune-inflammation index,SII)与胃癌患者预后的关系。方法:回顾性分析2010年6月至2015年6月青海大学附属医院收治的接受手术治疗的胃癌患者临床资料,计算其SII数值。相关性分析采用Spearman相关系数。应用受试者工作特征曲线(receiver operating characteristic curve,ROC)确定SII的最佳临界值,χ2检验评价SII与各项临床病理特征之间的关系。Kaplan-Meier法绘制生存曲线,并计算总生存时间(overall survival,OS),显著性分析采用Logrank检验。应用Cox比例风险模型进行预后因素的单因素和多因素分析。结果:共纳入771例患者,其中男性606例、女性165例,年龄25~81(56.91±9.546)岁。Spearmen相关性分析结果显示,SII与胃癌患者术后生存率呈正相关(r=0.399,P<0.001)。ROC曲线确定SII的最佳临界值为489.52,将771例胃癌患者分为低SII(L-SII)组(SII≤489.52)和高SII(H-SII)组(SII>489.52)。Kaplan-Meier分析显示L-SII组胃癌患者生存率明显优于H-SII组,两组总体生存率差异具有统计学意义(P<0.05)。Ⅰ、Ⅱ、Ⅲ期中L-SII组的5年生存率明显高于H-SII组(分别为81.8%vs.24.8%、56.5%vs.21.2%、62.5%vs.24.6%),差异具有统计学意义(P<0.05)。单因素分析显示H-SII是胃癌患者预后的危险因素(HR=3.919,95%CI:3.087~4.977,P<0.001),多因素分析提示术前外周血SII是胃癌患者预后的独立危险因素(HR=2.707,95%CI:2.074~3.533,P<0.001)。再次通过ROC曲线比较SII与其他指标预测胃癌患者预后的能力,显示SII具有更准确的预测能力。将SII联合Alb、CEA、CA125、WBC较单独预测具有更优的预测效能(AUC=0.786)。结论:SII是胃癌患者预后的独立危险因素。术前外周血SII的升高提示着更差的预后。

Dynamic Characteristics of High-speed Water-Lubricated Spiral Groove Thrust Bearing Based on Turbulent Cavitating Flow Lubrication Model

The water-lubricated bearings are usually the state of turbulent cavitating flow under high-speed conditions. And the distribution of cavitation bubbles and the interface effect between the two phases have not been included in previous studies on high-speed water-lubricated bearings. In order to study the influence of interface effect and cavitation bubble distribution on the dynamic characteristics of high-speed water-lubricated spiral groove thrust bearings(SGTB).A turbulent cavitating flow lubrication model based on two-phase fluid and population balance equation of bubbles was established in this paper. Stiffness and the damping coefficients of the SGTB were calculated using the perturbation pressure equations. An experimental apparatus was developed to verify the theoretical model. Simulating and experimental results show that the small-sized bubbles tend to generate in the turbulent cavitating flow when at a high rotary speed, and the bubbles mainly locate at the edges of the spiral groove. The simulating results also show that the direct stiffness coefficients are increased due to cavitation effect, and cross stiffness coefficients and damping coefficients are hardly affected by the cavitation effect. Turbulent effect on the dynamic characteristics of SGTB is much stronger than the cavitating effect.

A lubrication model for bubbly oil lubrication with interfacial effect and thermal effect using the theory of multiphase mixtures

Bubbly oil lubrication is a type of lubrication method.However,the lubrication model of the bubbly oil has not been thoroughly considered.This paper aims to investigate the modelling for bubbly oil lubrication considering the interfacial effect and thermal effect,and a theoretical model is established based on the theory of multiphase mixtures.The interfacial and thermal effects on the static characteristics of a thrust bearing are analyzed.A test rig for the thrust bearing is developed to measure the static characteristics of the bearing under bubbly oil lubrication.The results show that the bearing static characteristics,i.e.bearing temperature rise,film thickness,friction torque,and volume flow,increase with consideration of three interfacial effects;the bearing temperature rise increases but the film thickness,friction torque,and volume flow rate decrease with consideration of the three thermal effects;the thermal effect on the bearing static characteristics is greater than the interfacial effect.