RESUMO
Triboelectric nanogenerator (TENG) uses charge transfer between two asymmetric charge affinity materials such as metal and dielectrics. Metal electrode acts as charge collector from dielectrics and acts as charge transfer path to an external load, which model deals with only a net charge of metal electrode concerning electrical output. In this work, we found that metal electrode in triboelectric generator has non-negligible surface charge polarization causing open-circuit voltage difference in the model TENG system. The output voltage depends on the initial preparation conditions of the TENG for I-V measurements, even for the same measured charge densities. The measured output voltage difference with the same charge density implies that electric charges of TENG are composed of movable charges that affect current and voltage output and the bounded fixed charges that only affect open-circuit voltage.
RESUMO
BACKGROUND: Studies investigating the clinical outcome of intravascular ultrasound (IVUS)-guided primary percutaneous coronary intervention (PPCI) in patients with ST-segment elevation myocardial infarction (STEMI) show conflicting results. The aim of our study was to evaluate whether IVUS-guidedPPCI with drug-eluting stents (DESs) in STEMI patients improves clinical outcome. HYPOTHESIS: IVUS-guided PPCI is superior to angio-guided PPCI. METHODS: Three hundred forty-one patients who underwent PPCI for STEMI and survived the hospitalization were enrolled in this study. Two hundred sixteen (63.3%) patients were treated with angio-guided PPCI and 125 (36.7%) patients were treated with IVUS-guided PPCI. The primary endpoint was defined as the composite of death, myocardial infarction, target vessel revascularization, and target lesion revascularization at the 3-year follow-up visit. RESULTS: Male gender, dyslipidemia, and smoking were frequent in the IVUS-guided PPCI group. These patients had a higher rate of radial approach, adjunctive ballooning, thrombectomy, and the use of a glycoprotein IIb/IIIa inhibitor. The number and length of implanted stents were higher in the IVUS-guided PPCI group. The primary end point (18.1% vs 12.8%, P = 0.22) and stent thrombosis (2.8% vs 2.4%, P = 1.00) was not different between the groups. CONCLUSIONS: In our observational study, IVUS-guided PPCI with DESs in patients with STEMI did not improve clinical outcome or stent thrombosis.
