Experimental study and numerical analysis on dry friction and wear performance of co-continuous SiC/Fe-40Cr against SiC/2618 Al alloy composites

The dry friction and wear behaviors of co-continuous composites SiC/Fe–40Cr against SiC/Al 2618 alloy were investigated on a ring-on-ring friction and wear tester at sliding speed of 30-105 m/s under the load of 1.0-2.5 MPa. The experimental result reveals that the characteristic of two body abrasive wear and oxidation wear mechanisms are present for SiCn/2618 Al composite under higher load and sliding speed. SiC ceramic continuous network as the reinforcement can avoid composite from the third body wear that usually occurs in traditional particle reinforced composite. The mechanically mixed layer (MML) controls greatly the wear rate and friction coefficient of the composites. The composites tested at higher sliding speed exhibit higher value of friction coefficient and fluctuation, which is associated with the intermittent formation and removal of the MML. The wear and stress—strain behaviors of SiCn/Fe–40Cr against SiCn/Al 2168 at 30-105 m/s under 1.0-2.5 MPa were analyzed by finite element method with the software Solidwork2012 Simulation, respectively. The wear and stress–strain behavior of the composite predicted by the FEM correlated well with the experimental results.

清洗胃内黏液后行X线低张双对比造影对早期胃癌诊断效果观察(附100例报告)

目的探讨冲洗胃内液后行X线常规胃低张双重对比造影,对鉴别胃内早期癌及良性小溃疡的细微病变的价值。方法搜集经临床和手术、胃镜活检证实的100例,其中早期胃癌58例,良性溃疡30例,糜烂萎缩性胃炎12例。采用抑制胃内分泌液药物与插管注入氯化钠(包括西皮Ⅱ粉)冲洗排除胃内残液,然后行X线常规胃低张双重对比造影(“双连法”)以显示胃内微细早期癌及良性病变进行图像分析及统计。结果发现58例早期胃癌(Ⅱa型8例,Ⅱb型4例,Ⅱc型12例,Ⅲ型20例,Ⅱc+Ⅲ型14例),主要表现为“火山口”征、胃壁“双轨”征、基底凹凸不平“指压”征及“杵状”征,是鉴别良恶性病变依据。另30例良性溃疡表现为“星光状”,其周围黏膜纠集,自远而近由粗变细不中断,基底光整。12例糜烂萎缩性胃炎表现为小点状龛影,形态圆形,少数呈不规则、周围小透亮带及小环圈。结论“双连法”在鉴别诊断中有一定优势,可显示病变周边细微变化,可明确病变大小范围,易显示对胃前后壁隆起或凹陷性病变、浅表性凹陷病变。veinfovce可弥补常规双重造影不足,正确熟练应用可以明显提高早期胃癌诊断率。

EFFECTS OF RADIX ANGELICAE SINENSIS AND SHUANGHUANGLIAN ON A RAT MODEL OF CHRONIC PSEUDOMONAS AERUGINOSA PNEUMONIA

Objective. To study the effects of two kinds of Chinese herbal medicine, Radix angelicae sinensis(RAS)(当归)and Shuanghuanglian(SHL)(双黄连) on chronic Pseudomonas aeruginosa(PA)lung infection in a rat model mimicking cystic fibrosis(CF). Methods.Rats were divided into RAS, SHL and control groups. All rats were challenged intratracheally with alginate embedded PA and the treatments with herbal medicine started on the same day of challenge. The drugs were administered subcutaneously once a day for ten days and the control group was treated with sterile saline.The rats were sacrificed two weeks after challenge. Results. Significantly improved lung bacterial clearance(P<005, P<001) and milder macroscopic lung pathology (P<0005) were found in the two treated groups compared to the control group. In the SHL treated group, the neutrophil percent in the peripheral blood leukocytes(P<005), the antiPA IgG level in serum (P<005), the incidence of lung abscesses(P<0005) and the incidence of acute lung inflammation(P<005) were significantly lower than in the control group. The RAS treatment reduced fever(P<005), decreased the incidence of lung abscesses(P<0005) and lung mast cell number (P<005), and lowered antiPA IgG1 level in serum(P<005) when compared to the control group. The antiPA bacterial activity test in SHL was weakly positive whereas in RAS it was negative. Conclusion.The treatment with both herbal medicines could increase the resistance of the rats against PA lung infection and they therefore might be potential promising drugs for stimulation of the immune system in CF patients with chronic PA lung infection.

The Complex Analysis Method of Numerical Identification of Parameters of Quasiideals Processes in Doubly-Connected Nonlinear-Layered Curvilinear Domains

The method of numerical solving of nonlinear model problems of theory of a complex quasi-potential in doubly-connected nonlinear-layered curvilinear domains considering inverse influence function of flow on a conductivity coefficient of medium was developed on the basis of synthesis of numerical methods of the quasi-conformal mappings and summary representations in conjunction with domain decomposition by method Schwartz. The proposed algorithm allows finding the potential of the quasiideals field, construction a motion grid （fluid-flow grid） simultaneously defining the flow lines that separate of sub-domains constancy of coefficient conductivity and identification the piecewise-constant values of coefficient conductivity, the local flows for the known measurements on boundary of domain.

Dual reciprocity boundary element based block model for discontinuous deformation analysis

This paper presents a further development of the dual reciprocity boundary element method(DRBEM) with stepwise updating to pave the way for the introduction of boundary element mesh into the discontinuous deformation analysis(DDA). The advantage of the proposed method lies in its adoption of static fundamental solutions and reduction in the size of the governing equations by transforming the inertial term domain integrals to boundary integrals in the dynamic large displacement analysis. The unconditionally stable Newmark-β time integration method involving numerical damping to enhance the numerical stability is implemented for the dynamic analysis. In order to be coupled with the DDA to improve the deformability of the DDA block domains, a stepwise updating algorithm of the system variables is introduced. The stress updating in the analysis involved in the calculation of a domain integral and internal cells are used for the integration of the initial stress term. Several examples are used to verify the geometry-updated DRBEM model and satisfactory results have been obtained.