Association of urban inequality and income segregation with COVID-19 mortality in Brazil.

Socioeconomic factors have exacerbated the impact of COVID-19 worldwide. Brazil, already marked by significant economic inequalities, is one of the most affected countries, with one of the highest mortality rates. Understanding how inequality and income segregation contribute to excess mortality by COVID-19 in Brazilian cities is essential for designing public health policies to mitigate the impact of the disease. This paper aims to fill in this gap by analyzing the effect of income inequality and income segregation on COVID-19 mortality in large urban centers in Brazil. We compiled weekly COVID-19 mortality rates from March 2020 to February 2021 in a longitudinal ecological design, aggregating data at the city level for 152 Brazilian cities. Mortality rates from COVID-19 were compared across weeks, cities and states using mixed linear models. We estimated the associations between COVID-19 mortality rates with income inequality and income segregation using mixed negative binomial models including city and week-level random intercepts. We measured income inequality using the Gini index and income segregation using the dissimilarity index using data from the 2010 Brazilian demographic census. We found that 88.2% of COVID-19 mortality rates variability was between weeks, 8.5% between cities, and 3.3% between states. Higher-income inequality and higher-income segregation values were associated with higher COVID-19 mortality rates before and after accounting for all adjustment factors. In our main adjusted model, rate ratios (RR) per 1 SD increases in income inequality and income segregation were associated with 17% (95% CI 9% to 26%) and 11% (95% CI 4% to 19%) higher mortality. Income inequality and income segregation are long-standing hallmarks of large Brazilian cities. Risk factors related to the socioeconomic context affected the course of the pandemic in the country and contributed to high mortality rates. Pre-existing social vulnerabilities were critical factors in the aggravation of COVID-19, as supported by the observed associations in this study.

DFT calculations for structural prediction and applications of intercalated lamellar compounds.

The intercalated layered materials are commonly built from structures complex enough to have large unit cells and, because of this, calculations of their electronic structures are very demanding in terms of memory, processing and time. Also, the versatility of these compounds enables the synthesis of a large number of derived materials difficult to characterize. Only in the last two decades, a combination of theoretical methodologies and advances in processing made density-functional theory (DFT) calculations quite interesting as an investigation tool for this family of materials. Since the intercalated layered or lamellar compounds correspond to a large group of important classes of materials and their experimental data were, and are still being, generated, only a small part of the data comes from electronic structure simulations. In this review, we have listed some relevant types of intercalated lamellar materials, the useful methodologies implemented in the standard suit of codes for DFT calculations and examples of the many applications of the calculations to the understanding of physical and chemical properties, to the planning of novel materials with desirable properties, and even to assist the structural characterization, by simulating complex results from nuclear magnetic resonance, vibrational spectroscopy and powder X-ray diffraction. In addition to the properties simulated directly as observables, other quantities such as density of states, partial charges and electronic density difference, provide relevant information about the materials and their behavior under diverse physical and chemical conditions. The combination of the geometric, electronic and vibrational structures also leads to the simulations of thermodynamic potentials, entropy and phase diagrams in the solid state. This significant ensemble of research tools makes DFT calculations very compelling and useful to gain new insights into innovation developments for intercalated lamellar materials.