A structural vulnerability approach to older adult suicides: Trends and potential impacts of the COVID-19 pandemic in Clark County, NV (2017-2021).

The ongoing SARS-CoV-2 (COVID-19) pandemic has affected all aspects of life in the United States and around the world. This is particularly true for marginalized and vulnerable groups who face disproportionate levels of violence and premature death within their communities. While general impacts of the pandemic have been well-studied overall, little has been done to examine the correlation between COVID-19 and the risk of suicide among older adults. Older adults are particularly at risk because they face challenges including ageism, inadequate support systems, unreliable transportation, and frequent social isolation. Medicolegal casework offers a unique vantage of these issues, as it aims to identify manner of death which may be influenced by underlying structural vulnerabilities. The current research draws upon data collected from the Clark County Office of the Coroner/Medical Examiner. A sample of 871 older adults (aged 50+), whose manner of death was deemed a suicide between the years 2017-2021, were included in this analysis. Statistical analyses investigated differences between adults aged 50-64, 65-84, and 85+ years. Results suggest statistically significant changes in mechanism of death between pre-pandemic and pandemic periods, indicating a shift in risk factors related to social isolation and the home environment. Understanding such changes in trends directly affects the interpretation of skeletal data in forensic anthropology and thus, should be taken into consideration when developing structural vulnerability profiles. Furthermore, the inclusion of a structural vulnerability approach in forensic case reports has the potential to provide additional context for deaths by suicide and may help develop policies and procedures for mitigating future risk.

Effect of Crystallite Size on the Flexibility and Negative Compressibility of Hydrophobic Metal-Organic Frameworks.

Flexible nanoporous materials are of great interest for applications in many fields such as sensors, catalysis, material separation, and energy storage. Of these, metal-organic frameworks (MOFs) are the most explored thus far. However, tuning their flexibility for a particular application remains challenging. In this work, we explore the effect of the exogenous property of crystallite size on the flexibility of the ZIF-8 MOF. By subjecting hydrophobic ZIF-8 to hydrostatic compression with water, the flexibility of its empty framework and the giant negative compressibility it experiences during water intrusion were recorded via in operando synchrotron irradiation. It was observed that as the crystallite size is reduced to the nanoscale, both flexibility and the negative compressibility of the framework are reduced by ∼25% and ∼15%, respectively. These results pave the way for exogenous tuning of flexibility in MOFs without altering their chemistries.

Optimization of the wetting-drying characteristics of hydrophobic metal organic frameworks via crystallite size: The role of hydrogen bonding between intruded and bulk liquid.

HYPOTHESIS: The behavior of Heterogeneous Lyophobic Systems (HLSs) comprised of a lyophobic porous material and a corresponding non-wetting liquid is affected by a variety of different structural parameters of the porous material. Dependence on exogenic properties such as crystallite size is desirable for system tuning as they are much more facilely modified. We explore the dependence of intrusion pressure and intruded volume on crystallite size, testing the hypothesis that the connection between internal cavities and bulk water facilitates intrusion via hydrogen bonding, a phenomenon that is magnified in smaller crystallites with a larger surface/volume ratio. EXPERIMENTS: Water intrusion/extrusion pressures and intrusion volume were experimentally measured for ZIF-8 samples of various crystallite sizes and compared to previously reported values. Alongside the practical research, molecular dynamics simulations and stochastic modeling were performed to illustrate the effect of crystallite size on the properties of the HLSs and uncover the important role of hydrogen bonding within this phenomenon. FINDINGS: A reduction in crystallite size led to a significant decrease of intrusion and extrusion pressures below 100 nm. Simulations indicate that this behavior is due to a greater number of cages being in proximity to bulk water for smaller crystallites, allowing cross-cage hydrogen bonds to stabilize the intruded state and lower the threshold pressure of intrusion and extrusion. This is accompanied by a reduction in the overall intruded volume. Simulations demonstrate that this phenomenon is linked to ZIF-8 surface half-cages exposed to water being occupied by water due to non-trivial termination of the crystallites, even at atmospheric pressure.