Band Gap Engineering and Carrier Transport in TiO2 for Solar Energy Harvesting

TiO2 has been used in photocatalysis and photovoltaics because of its comprehensive combination of energy band structure, carrier transport, and inertness. However, wide band gap and relative slow carrier transport limits its full potential in these applications. 3.2 eV band gap of anatase indicates its low efficiency of utilizing full spectrum of solar light, and, band gap engineering was employed to address this issue. Specifically, nitrogen doping, iron doping, and N/Fe codoping were investigated for their photocatalytic effect. Doping was carried out in hydrothermal reactor by adding aliovalent ions to TiO2 precursor. Both N and Fe doping show the narrowing of band gap compared with the pristine TiO2. N-doping enhances its visible light photocatalytic performance, while Fe-doping and codoping result in poor photocatalysis. Further low temperature fluorescence spectra indicate the high recombination in Fe-doped and co-doped samples. The next issue is the relatively slow carrier transport in TiO2 nanoparticle-based dye sensitized solar cell (DSSC). Single crystalline rutile nanorod was studied in order to overcome this drawback. Synthesis was achieved with the assistance of microwave heating, and reaction rate was boosted due to this unique heating method. The carrier diffusion coefficient and life time of TiCl4 treated nanorod were systematically measured, and surface diffusion model is proposed to interpret observed phenomena. Combining band gap engineering (doping) and carrier transport (nanorod) research, doped nanorod was investigated. It is found that Nb doped nanorod shows higher conductivity, better back contact between FTO and nanorod, easy injection of electron from dye sensitizers to nanorods, and, consequently, less recombination. The efficiency of solar cell from Nb doped nanorod increases by almost 80% comparing with pure nanorod. What’s more, the conductive-AFM with nanoscale resolution provides unprecedented image of current path in nanorod, which could verify carrier transport model and shed light on engineering of nanostructure for superior performance

Importance of interfaces in hybrid perovskite solar cells

Photovoltaic devices based on hybrid organic-inorganic perovskite absorbers have reached outstanding performance over the past few years, surpassing power conversion efficiency of over 22%. In this talk we discuss the role of the interface in optimizing device performance as measured by both power conversion efficiency and stability. We present an examination of different perovskite active layers and interfacial electronic structure of these remarkable materials with functional oxide and organic contact layers. Interface formation of the active layer with different carrier transport materials has direct implications for performance of the resulting devices. We present interface studies, which permit identification of charge transfer mechanisms across the interface with chemical specificity and insight into the requirements for realizing high performance devices. Our findings from surface science approaches are combined with time resolved spectroscopy, structural studies and device level studies to validate impacts on carrier dynamics and demonstrate their technological relevance of interfacial insights

Electron and hole drift mobility measurements on methylammonium lead iodide perovskite solar cells

We report nanosecond domain time-of-flight measurements of electron and hole photocarriers in methylammonium lead iodide perovskite solar cells. The mobilities ranged from 0.06 to 1.4 cm2/Vs at room temperature, but there is little systematic difference between the two carriers. We also find that the drift mobilities are dispersive (time-dependent). The dispersion parameters are in the range of 0.4–0.7, and they imply that terahertz domain mobilities will be much larger than nanosecond domain mobilities. The temperature-dependences of the dispersion parameters are consistent with confinement of electron and hole transport to fractal-like spatial networks within nanoseconds of their photogeneration

Comparison of Six Different Percutaneous Coronary Intervention Guidance Modalities

Background: New randomized trials and modalities in guiding percutaneous coronary intervention (PCI) have become available. Objective: We aimed to compare the clinical outcomes of coronary angiography (CAG), intravascular ultrasound (IVUS), optical coherence tomography (OCT), fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and optical frequency domain imaging (OFDI)-guided PCI. Methods: A network meta-analysis was performed to compare different PCI guidance modalities. The clinical outcomes included major adverse cardiovascular events (MACE), all-cause death, myocardial infarction (MI), and target vessel/lesion revascularization (TVR/TLR). Odds ratio (OR) and corresponding 95% credible interval (CrI) were calculated. Results: Thirty-six randomized trials, including 19,042 patients, were included. In comparison with CAG, IVUS significantly reduced MACE (OR: 0.71; 95% CrI: 0.57 to 0.86) and TVR/TLR (OR: 0.53; 95% CrI: 0.43 to 0.66). MACE (OR: 1.44; 95% CrI: 1.02 to 2.08) and TVR/TLR (OR: 1.87; 95% CrI: 1.04 to 3.71) were significantly increased in the FFR group, compared with IVUS group. There were no significant differences in MACE or TVR/TLR among the left guidance modality comparisons. Differences in all-cause death or MI were not observed in any comparisons. Conclusions: IVUS could reduce MACE and TVR/TLR, compared with CAG or FFR. Therefore, IVUS may be the optimal modality in guiding PCI

The Optimal Strategy of Dual Antiplatelet Therapy after Percutaneous Coronary Intervention with Drug-Eluting Stent

Objective: To test the optimal strategy of dual antiplatelet therapy (DAPT) after implantation of drug-eluting stents (DESs) according to specific DAPT time and subsequent monotherapy. Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, and Web of Science to identify randomized controlled trials (RCTs). Six DAPT strategies were compared: 1-month DAPT followed by P2Y12 inhibitor monotherapy, 3-month DAPT followed by P2Y12 inhibitor monotherapy, 3-month DAPT followed by aspirin monotherapy, 6-month DAPT followed by aspirin monotherapy, 12-month DAPT, and >12-month DAPT. Pooled odd ratios (ORs) with 95% credible intervals (CrIs) were calculated to summarize the effect of each strategy tested. Results: We identified 24 RCTs containing 81,405 patients. In comparison with 12-month DAPT, 3-month DAPT followed by P2Y12 inhibitor monotherapy reduced net clinical events (OR: 0.72; CrI: 0.55–0.94). Major bleeding (OR: 0.57; CrI: 0.34–1.00) was marginally decreased without impact on ischemic events (OR: 0.93; CrI: 0.68–1.29). Moreover, the benefits of 3-month DAPT (P2Y12 inhibitor) were consistent for male patients with acute coronary disease, young age, complex lesion, single-vessel disease, low body mass index, and without diabetes. Although >12-month DAPT was associated with a lower risk of myocardial infarction (OR: 0.67; CrI: 0.51–0.93), the risk of major bleeding (OR: 1.70; CrI: 1.10–2.70) was increased. Conclusion: Among patients treated with DESs, 3-month DAPT followed by P2Y12 inhibitor monotherapy may be the optimal antiplatelet strategy, while DAPT beyond 1 year reduces myocardial infarction at the expense of increased major bleeding

Manejo Invasivo versus Conservador de Pacientes com IAMSSST Com Idade ≥ 75 Anos

Resumo Fundamento A eficiência do manejo invasivo em pacientes mais velhos (≥75 anos) com infarto do miocárdio sem supradesnivelamento do segmento ST (IAMSSST) permanece ambígua. Objetivos Avaliar a eficiência do tratamento invasivo em pacientes idosos com IAMSSST com base em metanálise e análise sequencial de estudo (TSA). Métodos Ensaios clínicos randomizados relevantes (ECR) e estudos observacionais foram incluídos. Os resultados primários foram morte por todas as causas, infarto do miocárdio, acidente vascular cerebral e hemorragia grave. O odd ratio agrupado (OR) e o intervalo de confiança de 95% (IC) foram calculados. P<0,05 foi considerado estatisticamente significativo. Resultados Cinco ECRs e 22 estudos observacionais com 1.017.374 pacientes foram incluídos.Com base nos resultados de ECR e TSA, o manejo invasivo foi associado a menores riscos de infarto do miocárdio (OR: 0,51; 95% IC: 0,40-0,65; I2=0%), eventos cardiovasculares adversos maiores (MACE; OR: 0,61; 95% IC: 0,49-0,77; I2=27,0%) e revascularização (OR: 0,29; 95% IC: 0,15-0,55; I2=5,3%) em comparação com o tratamento conservador. A combinação de resultados de ECRs e estudos observacionais com ajuste multivariável mostrou riscos consistentemente menores de morte por todas as causas (OR: 0,57; IC 95%: 0,50-0,64; I2 = 86,4%), infarto do miocárdio (OR: 0,63; IC 95%: 0,56 -0,71; I2=0%), acidente vascular cerebral (OR: 0,59; 95% IC: 0,51-0,69; I2=0%) e MACE (OR: 0,64; 95% IC: 0,54-0,76; I2=43,4%). O melhor prognóstico associado ao manejo invasivo também foi observado em cenários do mundo real. No entanto, para pacientes com idade ≥85 anos, o manejo invasivo pode aumentar o risco de sangramento maior (OR: 2,68; IC 95%: 1,12-6,42; I2=0%). Conclusões O manejo invasivo foi associado a menores riscos de infarto do miocárdio, MACE e revascularização em pacientes idosos com IAMSSST,no entanto, pode aumentar o risco de sangramento maior em pacientes com idade ≥85 anos

Beta-Blocker Use after Discharge in Patients with Acute Myocardial Infarction in the Contemporary Reperfusion Era

Background and objectives: The effect of beta-blocker use after discharge on patients with acute myocardial infarction (AMI) in the contemporary reperfusion era remains ambiguous. By applying meta-analysis, we sought to assess the role of beta-blockers in the contemporary reperfusion era. Materials and Methods: Randomized controlled trials (RCT) and observational studies using propensity score matching, comparing use of beta-blockers with non-use of beta-blockers, in patients with AMI after discharge. The primary outcome was all-cause mortality. Odds ratios (OR) and associated 95% confidence intervals (CI) were calculated. Results: One RCT and eight observational studies, containing 47,339 patients with AMI, were included. Compared with non-use of beta-blockers, beta-blocker use after discharge may have reduced the risk of all-cause mortality (OR: 0.70, 95% CI: 0.61 to 0.80, I2 = 14.4%), cardiac death (OR: 0.63, 95% CI: 0.44 to 0.91, I2 = 22.8%), myocardial infarction (OR: 0.73, 95% CI: 0.62 to 0.86, I2 = 0), and revascularization (OR: 0.92, 95% CI: 0.85 to 0.99, I2 = 0). No significant differences were found in major adverse cardiovascular events (MACE, OR: 0.88, 95% CI: 0.66 to 1.17, I2 = 78.4%), heart failure (OR: 0.56, 95% CI: 0.29 to 1.08, I2 = 0) or stroke (OR: 1.13, 95% CI: 0.92 to 1.39, I2 = 0). For patients with preserved left ventricular function, beta-blocker use after discharge may have also reduced the risk of all-cause mortality (OR: 0.61, 95% CI: 0.44 to 0.84, I2 = 0). Conclusions: Use of beta-blockers after discharge may still be beneficial for AMI patients in the contemporary reperfusion era, with or without preserved left ventricular function

Research on Optimization of Linkage Operation of Integrated Energy System in Industrial Parks based on Chaotic Particle Swarm Algorithm

Industrial parks cover a variety of production capacities and energy-consuming entities, with large load demand and complex energy-using structure, and common problems such as low energy utilization efficiency and unreasonable energy structure. The construction of an integrated energy system (IES) with a combined cooling, heating and power system as the core unit in the industrial park is of great significance for achieving reliable, efficient and clean energy use in the park. Therefore, this article is based on the integrated energy system of the industrial park, aims at the lowest total cost of park operators, and considers the constraints of grid node balance, equipment output and energy storage equipment, and constructs source-grid-load-storage linkage operation optimization model, and build a chaotic particle swarm algorithm (CPSO) to solve the model. Finally, a typical industrial park in my country is taken as an example to analyze the scientificity of the model