Revealing the microstructures and seepage characteristics in the uncured rubber-cord composites using micro-computed tomography and lattice Boltzmann approach

The internal microstructure distribution of cord-rubber-air during the processing of uncured rubber-cord composites (URCs) determines the finished product's performance. For the first time, we used computed tomography (CT) and the lattice Boltzmann method (LBM) to establish a geometrical representation model of the real microscopic pore-fracture structures of URCs and investigate the seepage law of fluid in porous URCs, where the reinforced rubber formula was originally designed to reduce CT artifacts of cord. The results showed that the average porosity and pore radius of the original cord (0.2711 and 15.53 μm, respectively) were considerably larger than those of the URCs (0.0509 and 4.46 μm, respectively); the pore number of the cord was the largest when the pore radius was 5–10 μm, accounting for 29.36% of the total number; however, the pore number accounted for 31.36% of the total number of the URCs when the pore radius was 2–3 μm. Moreover, the characteristics of the pore/throat surface area and pore volume/throat length exhibited perfect consistent patterns with those of the pore radius. Furthermore, the fluid flow velocity increased in both cord and URCs as the displacement differential pressure increased, but decreased dramatically as the fluid kinematic viscosity increased. The critical values of displacement differential pressure and kinematic viscosity were different in the cord and URCs samples, presenting 11.1209 Pa/1.3696 × 10−3 m2/s and 14.2984 Pa/2.8869 × 10−4 m2/s, respectively. This phenomenon should be attributed that when the uncured rubber was injected into the original cord sample, its porosity decreased, its pore radius decreased, the number of micro-scale pores increased, and flow resistance became larger, resulting in a higher critical value of displacement differential pressure and a lower critical value of kinematic viscosity

Health-status outcomes with invasive or conservative care in coronary disease

BACKGROUND In the ISCHEMIA trial, an invasive strategy with angiographic assessment and revascularization did not reduce clinical events among patients with stable ischemic heart disease and moderate or severe ischemia. A secondary objective of the trial was to assess angina-related health status among these patients. METHODS We assessed angina-related symptoms, function, and quality of life with the Seattle Angina Questionnaire (SAQ) at randomization, at months 1.5, 3, and 6, and every 6 months thereafter in participants who had been randomly assigned to an invasive treatment strategy (2295 participants) or a conservative strategy (2322). Mixed-effects cumulative probability models within a Bayesian framework were used to estimate differences between the treatment groups. The primary outcome of this health-status analysis was the SAQ summary score (scores range from 0 to 100, with higher scores indicating better health status). All analyses were performed in the overall population and according to baseline angina frequency. RESULTS At baseline, 35% of patients reported having no angina in the previous month. SAQ summary scores increased in both treatment groups, with increases at 3, 12, and 36 months that were 4.1 points (95% credible interval, 3.2 to 5.0), 4.2 points (95% credible interval, 3.3 to 5.1), and 2.9 points (95% credible interval, 2.2 to 3.7) higher with the invasive strategy than with the conservative strategy. Differences were larger among participants who had more frequent angina at baseline (8.5 vs. 0.1 points at 3 months and 5.3 vs. 1.2 points at 36 months among participants with daily or weekly angina as compared with no angina). CONCLUSIONS In the overall trial population with moderate or severe ischemia, which included 35% of participants without angina at baseline, patients randomly assigned to the invasive strategy had greater improvement in angina-related health status than those assigned to the conservative strategy. The modest mean differences favoring the invasive strategy in the overall group reflected minimal differences among asymptomatic patients and larger differences among patients who had had angina at baseline

Initial invasive or conservative strategy for stable coronary disease

BACKGROUND Among patients with stable coronary disease and moderate or severe ischemia, whether clinical outcomes are better in those who receive an invasive intervention plus medical therapy than in those who receive medical therapy alone is uncertain. METHODS We randomly assigned 5179 patients with moderate or severe ischemia to an initial invasive strategy (angiography and revascularization when feasible) and medical therapy or to an initial conservative strategy of medical therapy alone and angiography if medical therapy failed. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A key secondary outcome was death from cardiovascular causes or myocardial infarction. RESULTS Over a median of 3.2 years, 318 primary outcome events occurred in the invasive-strategy group and 352 occurred in the conservative-strategy group. At 6 months, the cumulative event rate was 5.3% in the invasive-strategy group and 3.4% in the conservative-strategy group (difference, 1.9 percentage points; 95% confidence interval [CI], 0.8 to 3.0); at 5 years, the cumulative event rate was 16.4% and 18.2%, respectively (difference, 121.8 percentage points; 95% CI, 124.7 to 1.0). Results were similar with respect to the key secondary outcome. The incidence of the primary outcome was sensitive to the definition of myocardial infarction; a secondary analysis yielded more procedural myocardial infarctions of uncertain clinical importance. There were 145 deaths in the invasive-strategy group and 144 deaths in the conservative-strategy group (hazard ratio, 1.05; 95% CI, 0.83 to 1.32). CONCLUSIONS Among patients with stable coronary disease and moderate or severe ischemia, we did not find evidence that an initial invasive strategy, as compared with an initial conservative strategy, reduced the risk of ischemic cardiovascular events or death from any cause over a median of 3.2 years. The trial findings were sensitive to the definition of myocardial infarction that was used