Tailing sand is the residue mineral from tin extraction that contains between 94% and 99.5% silica, which can be used as moulding sand. It is found in abundance in the Kinta Valley in the state of Perak, Malaysia. Adequate water content and clay in moulding sand are important factors for better strength and
casting quality of products made from tailing sand. Samples of tailing sand were investigated according
to the American Foundrymen Society (AFS) standard. Cylindrical test pieces of Ø50 mm×50 mm in height from various sand-water ratios were compacted by applying three ramming blows of 6666g each using a Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using a Ridsdale-Dietert universal sand strength machine. Before the tests were conducted, moisture content of the tailing sand was measured using a moisture analyser. A mixture bonded with 8% clay possesses higher green compression strength compared to samples bonded with 4% clay. The results also show that in order to achieve maximum green compression strength, the optimum allowable moisture content for mixtures bonded with 8% clay is ranged between 3.75 and 6.5% and for mixtures bonded with 4% clay is 3-5.5%.
Current guidelines recommend 6-12 months of dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) followed by aspirin monotherapy indefinitely. We aimed to assess the efficacy and safety of clopidogrel vs aspirin in the post-PCI population after completing DAPT. We systematically searched 5 electronic databases to identify studies comparing clopidogrel with aspirin following completion of DAPT after PCI. We pooled outcomes for major adverse cardiac events (MACE), cardiac death, all-cause death, major bleeding, myocardial infarction (MI), and stroke. We included 5 studies with 13,850 patients, of whom 5601 (40.4%) received clopidogrel. Mean follow-up was 12-36 months. All patients received drug-eluting stents. Duration of DAPT before antiplatelet monotherapy was 1-18 months. Clopidogrel was associated with reductions in MACE (Risk ratio [RR] 0.77, 95% confidence interval [CI] 0.65-0.91), any stroke (RR 0.51; 95% confidence interval [CI] 0.35-0.76), ischemic stroke (RR 0.55; 95% CI 0.32-0.94), and hemorrhagic stroke (RR 0.24; 95% CI 0.09-0.68) when compared with aspirin. Cardiac death (RR 0.87; 95% CI 0.53-1.41), all-cause death (RR 1.06; 95% CI 0.81-1.39), major bleeding (RR 0.74; 95% CI 0.43-1.29), MI (RR 1.01; 95% CI 0.64-1.60), repeat revascularization (RR 0.88; 95% CI 0.71-1.09), target vessel revascularization (RR 0.76; 95% CI 0.52-1.13), and stent thrombosis (RR 0.96; 95% CI 0.35-2.59) were not significantly different among groups. Compared with aspirin, clopidogrel was associated with reductions in MACE and stroke (ischemic and hemorrhagic) following DAPT completion after PCI. There were no significant differences in mortality, major bleeding, MI, and repeat revascularization between groups.