RESUMEN
Halide perovskites are materials for future optical displays and solar cells. Electron donor-acceptor perovskite heterostructures with distinguishing halide compositions are promising for transporting and harvesting photogenerated charge carriers. Combined e-beam lithography and anion exchange are promising to develop such heterostructures but challenging to prepare multiple heterojunctions at desired locations in single crystals. We demonstrate swift laser trapping-assisted band gap engineering at the desired locations in MAPbBr3 microrods, microplates, or nanocrystal thin films. The built-in donor-acceptor double and multi-heterojunction structures let us transport and trap photogenerated charge carriers from wide-band gap bromide to narrow-band gap iodide domains. We discuss the charge carrier transport and trapping mechanisms from the viewpoints of engineered bands and band continuity. This work offers a convenient method for designing single-, double- and multi-heterojunction donor-acceptor halide perovskites for photovoltaic, photonic, and electronic applications.
RESUMEN
BACKGROUND AND AIMS: Chronic obstructive pulmonary disease (COPD) is thought to have increased association with metabolic syndrome (MS) which represents a cluster of factors that increase the risk of cardiovascular diseases and diabetes mellitus. However, the extent of association of COPD with MS and its individual components are still an unsettled issue, and it is likely to vary from population to population. Under the above context, this study was undertaken to investigate the association of MS and its components with COPD. MATERIALS AND METHODS: With a cross-sectional analytic design, 77 COPD and an equal number of non-COPD (apparently healthy) participants were studied purposively. The two groups were found to be matched by age, sex, and monthly income groups. The data of COPD patients and non-COPD participants were collected from a tertiary level hospital in Kolkata and a locality of Greater Kolkata, respectively. They were interviewed, and the frequencies of MS were assessed using 3 criteria (National Cholesterol Education Program-Third Adult Treatment Panel [NCEP ATP III], modified NCEP ATP III, and International Diabetic Federation [IDF]). Anthropometric measurements were taken, and fasting blood sample was collected to test the fasting blood glucose (FBG), triglyceride (TG), and high-density lipoprotein (HDL) of respondents. Logistic regression was applied to estimate the odds ratio (OR). RESULTS: Among the COPD subjects, 44%, 46%, and 31% had coexisting MS as defined by NCEP ATP III, modified NCEP ATP III, and IDF criteria, respectively. The corresponding percentages in the non-COPD groups were 31%, 38%, and 32%. On multivariate analysis, a significant association of MS (P < 0.015) with COPD was found only when the NCEP ATP III criteria were used. The (mean ± standard deviation) FBG concentration among COPD and non-COPD groups was 130 ± 65 mg/dl and 97 ± 26 mg/dl, which was significantly different (P < 0.001). The difference in systolic blood pressure (SBP) (P < 0.063) and HDL level (P < 0.058) lied just outside the statistical significance among COPD and non-COPD groups. Gender, exercise habit, family history of hypertension, and smoking habits were important confounders for the association of COPD with individual MS components. Using NCEP ATP III criteria, female gender (OR = 3.48), COPD groups (OR = 3.05), and family history of hypertension (OR = 3.31) were found as determinants (P < 0.05) of MS. Using modified NCEP ATP III criteria, female (OR = 3.66) and family history of hypertension (OR = 3.84) were found as determinants (P < 0.05) of MS. CONCLUSIONS: COPD is associated with MS only when the NCEP ATP III is used for the diagnosis of MS. No association can be revealed on using the IDF criteria for MS. Body mass index (BMI), and waist circumference does not seem to be appropriate measures for assessing the presence of MS among COPD patients. Among the components of MS BMI, SBP, FBG, TG, and HDL are significantly associated with COPD.