Y型聚乙二醇干扰素琢-2b注射液治疗HCV基因2/3型慢性丙型肝炎患者疗效和安全性的多中心随机对照试验研究

目的以标准剂量的聚乙二醇干扰素(Peg IFN)α-2a联合利巴韦林作为阳性对照,评价新型试验药物Y型Peg IFNα-2b注射液联合利巴韦林治疗2型/3型慢性丙型肝炎(CHC)患者的疗效和安全性。方法采用多中心、随机开放、阳性药对照的Ⅲ期临床试验,筛选符合要求的2型/3型CHC患者,按照2:1的比例随机分配到Y型Peg IFNα-2b组和Peg IFNα-2a组,同时口服利巴韦林,疗程24 w,停药随访24 w。采用Abbott Real Time HCV Genotype II检测HCV基因型,采用Cobas Taq Man实时定量PCR法检测血清HCV RNA水平。详细记录不良事件。主要疗效指标为持续病毒学应答(SVR),并进行非劣效检验。结果本试验实际入组2型/3型CHC患者255例,实际治疗241例。全分析集(FAS)数据显示,158例试验组和83例对照组患者SVR分别为85.4%(95%CI 79.94%~90.94%)和79.5%(95%CI 70.84%~88.20%,P=0.2402);对符合方案分析集(PPS)人群分析显示,试验组和对照组患者SVR分别为87.9%(95%CI 82.45%~93.27%)和85.9%(95%CI 77.82%~94.01%,P=0.7060),率差的95%可置信区间均符合非劣效标准;对PPS人群分析显示,85.8%受试者获得了早期病毒学应答(RVR),RVR的阳性预测值为90.1%;试验组和对照组不良事件发生率相似,分别为95.6%和95.2%,严重不良事件发生率分别为3.8%和3.6%。结论应用Peg IFNα联合利巴韦林治疗2型/3型CHC患者,新型试验药物Y型Peg IFNα-2b具有与对照药物Peg IFNα-2a相似的疗效和安全性。国家科技部“十二五”重大专项(编号:2012ZX10002-003)；“重大新药创制”十二五科技重大专项(编号:2012ZX09303019)

非饱和颗粒介质土水特征曲线的离散元模拟

提出一种"气泡液体重分布-颗粒受力折减"的计算方法解决上述问题,首次将三维颗粒离散元模拟非饱和颗粒介质的能力扩展到环锁区和毛细区。应用该方法,得到了三维颗粒介质完整的土水特征曲线。进一步,模拟了砂土和粉土的土水特征曲线,结果表明颗粒粒径是影响土水特征曲线的重要因素,而颗粒级配的影响较小

孔压对泥石流流通距离的影响

泥石流是我国山区重要的自然灾害之一,对我们山区经济和人民财产造成十分严重的危害。泥石流是典型的水土混合介质流动,且受到复杂的山地环境影响,目前为止泥石流运动过程的力学方程及其数值方法很不成熟。总体说来,泥石流动力过程至少应该包括以下几个方面:1)颗粒材料(运动土体)的介质特性;2)孔压作用;3)地形效应的影响;4)侵蚀作用。本研究在Savage-Hutter方程基础上,引入孔压作用,对孔压进行初步简化处理,暂不考虑其生成和消散过程,最终形成描述以上1)~3)三个重要方面的泥石流动力过程力学模型。采用Weno方法计算泥石流的力学方程,初步评估孔压作用对泥石流流通距离的影响。结果表明,随着孔压增长,泥石流的流通距离增长十分明显。图1给出了不同孔压条件下泥石流的流通距离

碎屑流动力过程的数值模拟

碎屑流是一种常见的地质灾害,往往对流通路径上的各种设施造成严重灾难,同时碎屑流还给泥石流提供物质来源,从而形成不良堆积坝堵塞河道或形成堰塞湖。本文建立了碎屑流动力过程的力学模型及其高分辨率数值算法,预测和评估碎屑流的铺展和堆积过程。应用该数值模型,首先计算了一维经典溃坝问题,计算结果和理论解符合较好。其次,初步分析了碎屑流和障碍物相互作用后的分流和堆积规律,并讨论了碎屑流灾害防治的可能方案

中国科学院力学研究所流固耦合系统力学重点实验室;

堤坝在洪水期间由于上下游较大水位差极易发生管涌灾害。管涌发生时,细颗粒逐渐被水流带走,粗颗粒形成的骨架承载力逐渐降低,直至不足以支撑外部载荷时,灾害发生。雨季和洪水期间,此类灾害在长江流域、珠江流域以及东北地区的漫长堤防处经常发生,对人民生活、经济建设造成严重影响。管涌灾害三个重要的过程分别是细颗粒的启动条件和输运过程、颗粒介质的力学性能如何随颗粒流失变化以及整个堤坝在颗粒介质力学性能弱化后的变形和破坏过程。已有工作中对第二个过程中的科学问题研究甚少,故本文研究颗粒流失对颗粒介质力学性能的弱化作用。本文在砂土状态相关本构模型框架上,假设少量颗粒流失对临界状态方程影响可以忽略,通过引入颗粒流失表..

nonequispaced fast fourier transform on parallel hexagon

本文研究平行六边形区域上的非均匀节点离散傅立叶变换的快速算法及其实现.首先在晶格(Lattice)的框架下建立了平行六边形区域上的非均匀节点离散傅立叶变换(NDFTH).在此基础上设计了平行六边形区域上的非均匀节点快速傅立叶变换(NFFTH)算法.其核心思想是以局部性态良好的窗口函数为基底,以平行六边形区域上均匀节点快速傅立叶变换(FFTH)为时空域和频域转换工具,通过在时空域和频域上截取其展开级数的少量几项来快速近似计算,最终降低其计算复杂度.数值计算结果表明,本文算法是合理、稳定、高效的

Numerical Triaxial Apparatus and Application

A numerical triaxial apparatus based on discrete element method is developed on the platform of Yade using Python script. A DEM model with rolling resistance contact considered is proposed for dense granular materials, which is then applied in triaxial compression test of Chende sand. Stress-strain response and volume-axial strain response of the DEM model agree well with that of experiments, with a good prediction of dilatancy angle. Degradation of granular materials duo to particle erosion is also investigated using triaxial compression tests. It is indicated that peak friction angle decreases with the remove of particles if strong force network of granular materials is destroyed

Mesoscale analysis of the suction stress characteristic curve for unsaturated granular materials

There is still no theoretical framework accounting for linkage between seepage and deformation of unsaturated granular materials. Using a mesoscale liquid bridge model, we propose the first approach for deriving the suction stress characteristic curve (SSCC). Then, we verify the method by obtaining both the soil -water characteristic curve and SSCC for cubic and tetrahedral granular packing. The approach is further validated by generating the SSCCs of granular packings with different particle size distributions. On this basis, a new two -parameter model is suggested that satisfactorily predicts the SSCCs of various real granular materials. The nonlinear variation of strength versus suction is also properly described by a new formula for three kinds of soil. We believe that this SSCC model can help resolve solid -fluid coupling in seepage and deformation problems in unsaturated granular engineering. (C) 2020 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved

Seepage-stress coupled modeling for rainfall induced loess landslide

Although rainfall is rare on the Loess Plateau of western China, landslides occur frequently there in rainy season. Surveys report that landslide hazards always follow heavy rains. In this study, a seepage-stress coupling model for rainfall induced landslide is used to examine an actual disastrous event in Yulin by the end of July, 2017. The effects of rainfall duration, rainfall intensity and soil weakening on slope stability are studied in detail. The results illustrate that the safety factor drops sharply at first and then is gradually declining to below 1.05 during additional two days of heavy rain. With soil strength softening considered, the slope would be more unstable, in which the weakening in soil cohesion is found to be a more sensitive factor. (C) 2019 The Authors. Published by Elsevier Ltd on behalf of The Chinese Society of Theoretical and Applied Mechanics