Effect of Al-deposition on erosion resistance of plasma sprayed thermal barrier coating

A columnar Al film was firstly deposited on the top of 7%Y2O3？stabilized zirconia （7YSZ） ceramic coating in thermal barrier coating （TBC） system by magnetron sputtering. A vacuum treatment was then carried out at 700 °C for 1 h and 900 °C for 5 h to improve the erosion resistance of Al-deposited TBC. Aα-Al2O3 layer was in situ synthesized on the top of 7YSZ coating via vacuum heat treatment. The microstructure evolution of Al-deposited TBC illustrated that a loose surface-layer and a dense sub-layer formed on the top of 7YSZ coating after vacuum treatment. The phase structures of the as-sprayed TBC and the Al-deposited TBC after vacuum heat treatment were characterized by X-ray diffraction （XRD） and transmission electron microscope （TEM） assisted with focused ion beam （FIB）. Particulate erosion resistances of the as-sprayed TBC and treated TBC were compared at room temperature. In addition, erosion mechanism and schematic diagram were proposed. The results show that the Al-deposited TBC after vacuum heat treatment has better particulate erosion resistance than the as-sprayed one.

Impact of cigarette smoking on response to interferon therapy in chronic hepatitis C Egyptian patients

AIM:Smoking may affect adversely the response rate to interferon-α.Our objective was to verify this issue among chronic hepatitis C patients. METHODS:Over the year 1998,138 chronic hepatitis C male Egyptian patients presenting to Cairo Liver Center, were divided on the basis of smoking habit into:group I which comprised 38 smoker patients(>30 cigarettes/d) and group Ⅱ which included 84 non-smoker patients. Irregular and mild smokers(16 patients)were excluded. Non eligible patients for interferon-α therapy were excluded from the study and comprised 3/38(normal ALT)in group I and 22/84 in group Ⅱ(normal ALT,advanced cirrhosis and thrombocytopenia).Group I was randomly allocated into 2 sub-groups:group Ia comprised 18 patients who were subjected to therapeutic phlebotomy while sub-group Ib consisted of 17 patients who had no phlebotomy.In sub-group la,3 patients with normal ALT after repeated phlebotomies were excluded from the study.Interferon-α 2b 3 MU/TIW was given for 6 mo to 15 patients in group Ia,17 patients in group Ib and 62 patients in group Ⅱ. Biochemical,virological end-of-treatment and sustained responses were evaluated. RESULTS:At the end of interferon-α treatment,ALT was normalized in 3/15 patients(20%)in group Ia and 2/17 patients(11.8%)in group Ib compared to17/62 patients (27.4%)in group Ⅱ(P=0.1).Whereas 2/15 patients(13.3%) in group Ia.and 2/17 patients(11.8%)in group Ib lost viraemia compared to 13/62 patients(26%)in group Ⅱ (P=0.3).Six months later,ALT was persistently normal in 2/15 patients(13.3%)in group 1a and 1/17 patients (5.9%)in group Ib compared to 9/62 patients(14.5%)in group Ⅱ(P=0.47).Viraemia was eliminated in 1/15 patients (6.7%)in group Ia and 1/17 patients(5.9%)in group Ib compared to 7/62 patients(11.3%) in group Ⅱ,but the results did not mount to statistical significance(P=0.4). CONCLUSION:Smokers suffering from chronic hepatitis C tend to have a lower response rate to interferon-α compared to non-smokers.Therapeutic phlebotomy improves the response rate to interferon-α therapy among this group.

A Kind of Predator-prey System of Holling Type II and Interaction Perturbation with Impulsive Effect

A kind of predator-prey system of Holling typeⅡand interaction perturbation with impulsive effect is presented.By using Floquet theory and small amplitude perturbations skills,the locally asymptotical stability of prey-eradication periodic solution and the permanence of the system are discussed and the corresponding threshold conditions are given respectively.Finally,the existence of positive periodic solution is investigated by the bifurcation theory.

Near-fault directivity pulse-like ground motion effect on high-speed railway bridge

The vehicle-track-bridge(VTB)element was used to investigate how a high-speed railway bridge reacted when it was subjected to near-fault directivity pulse-like ground motions.Based on the PEER NAG Strong Ground Motion Database,the spatial analysis model of a vehicle-bridge system was developed,the VTB element was derived to simulate the interaction of train and bridge,and the elasto-plastic seismic responses of the bridge were calculated.The calculation results show that girder and pier top displacement,and bending moment of the pier base increase subjected to near-fault directivity pulse-like ground motion compared to far-field earthquakes,and the greater deformation responses in near-fault shaking are associated with fewer reversed cycles of loading.The hysteretic characteristics of the pier subjected to a near-fault directivity pulse-like earthquake should be explicitly expressed as the bending moment-rotation relationship of the pier base,which is characterized by the centrally strengthened hysteretic cycles at some point of the loading time-history curve.The results show that there is an amplification of the vertical deflection in the girder's mid-span owing to the high vertical ground motion.In light of these findings,the effect of the vertical ground motion should be used to adjust the unconservative amplification constant 2/3 of the vertical-to-horizontal peak ground motion ratio in the seismic design of bridge.