Tribological performance of an H-DLC coating prepared by PECVD

Carbon-based coatings are of wide interest due to their application in machine elements subjected to continuous contact where fluid lubricant films are not permitted. This paper describes the tribological performance under dry conditions of duplex layered H-DLC coating sequentially deposited by microwave excited plasma enhanced chemical vapour deposition on AISI 52100 steel. The architecture of the coating comprised Cr, WC, and DLC (a-C:H) with a total thickness of 2.8 μm and compressive residual stress very close to 1 GPa. Surface hardness was approximately 22 GPa and its reduced elastic modulus around 180 GPa. Scratch tests indicated a well adhered coating achieving a critical load of 80 N. The effect of normal load on the friction and wear behaviours were investigated with steel pins sliding against the actual coating under dry conditions at room temperature (20 ± 2°C) and 35-50% RH. The results show that coefficient of friction of the coating decreased from 0.21 to 0.13 values with the increase in the applied loads (10-50 N). Specific wear rates of the surface coating also decrease with the increase in the same range of applied loads. Maximum and minimum values were 14 × 10-8 and 5.5 × 10-8 mm-3/N m, respectively. Through Raman spectroscopy and electron microscopy it was confirmed the carbon-carbon contact, due to the tribolayer formation on the wear scars of the coating and pin. In order to further corroborate the experimental observations regarding the graphitisation behaviour, the existing mathematical relationships to determine the graphitisation temperature of the coating/steel contact as well as the flash temperature were used

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

OP53 explaining Scottish coronary heart disease mortality trends between 2000 and 2010: socioeconomic analyses using the impact sec model

Background: Coronary heart disease (CHD) mortality rates have halved in recent decades. However, CHD remains the largest cause of death in Scotland generating persistent socioeconomic inequalities. A socioeconomic quantification of the prevention and treatment contributions to these mortality reductions might help inform future health policies.<p></p> Methods: IMPACTsec, a previously validated policy model, was used to apportion the Scottish CHD mortality decline between 2000 and 2010 to changes in six major CHD risk factors and to 40 treatments in nine patient groups. Analyses were stratified by gender, age and Scottish Index of Multiple Deprivation quintiles. Uncertainties around estimates were explored using probabilistic sensitivity analysis.<p></p> Results: There were 5770 fewer CHD deaths in 2010 than would have been expected if 2000 mortality rates had persisted unchanged. This reflected an overall 43% fall in CHD mortality rates (from 262 to 148 deaths per 100,000), but with a slower 37% decline amongst the two most deprived quintiles. The IMPACTsec model explained approximately 83% of the CHD mortality fall. Treatments accounted for approximately 44% of the fall. This benefit was fairly evenly distributed across deprivation quintiles. Three treatments contributed over half of these benefits: statins for primary prevention (13%) and medical therapies for stable angina (9%) and secondary prevention following revascularisation or myocardial infarction (11%). Risk factors accounted for approximately 39% of the mortality fall overall, with the largest contribution in the most deprived quintile (44%) and the least in the most affluent quintile (36%). The decline in systolic blood pressure made the biggest contribution (37%), exceeding that of smoking (4%), total cholesterol (9%) and inactivity (2%); the latter three demonstrating socioeconomic gradients. However, increases in diabetes and obesity negated some of these benefits potentially exacerbating mortality by -8% and -4% respectively. The diabetes contribution to the exacerbation of mortality showed strong socioeconomic patterning (-12% for the most deprived quintile compared to -5% for the most affluent).<p></p> Conclusion: This IMPACTsec analysis suggests that NHS medical treatments have made a large and equitable contribution to the recent decline in Scottish CHD mortality. The substantial contribution that improvements in risk factor profiles made on CHD mortality rates was diminished by adverse trends in obesity and diabetes; the latter having an adverse socioeconomic gradient. Population-wide interventions can be powerful, rapid and equitable. However, more radical policies will be required if the CHD mortality decline is to continue in future decades while reducing inequalities.<p></p&gt