Accurate Nanoscale Crystallography in Real-Space Using Scanning Transmission Electron Microscopy.

Here, we report reproducible and accurate measurement of crystallographic parameters using scanning transmission electron microscopy. This is made possible by removing drift and residual scan distortion. We demonstrate real-space lattice parameter measurements with <0.1% error for complex-layered chalcogenides Bi2Te3, Bi2Se3, and a Bi2Te2.7Se0.3 nanostructured alloy. Pairing the technique with atomic resolution spectroscopy, we connect local structure with chemistry and bonding. Combining these results with density functional theory, we show that the incorporation of Se into Bi2Te3 causes charge redistribution that anomalously increases the van der Waals gap between building blocks of the layered structure. The results show that atomic resolution imaging with electrons can accurately and robustly quantify crystallography at the nanoscale.

Atom column indexing: atomic resolution image analysis through a matrix representation.

Here, we report the development of an approach to map atomic resolution images into a convenient matrix representation. Through the combination of two-dimensional Gaussian fitting and the projective standard deviation, atom column locations are projected onto two noncollinear reference lattice vectors that are used to assign each a unique (i, j) matrix index. By doing so, straightforward atomic resolution image analysis becomes possible. Using practical examples, we demonstrate that the matrix representation greatly simplifies categorizing atom columns to different sublattices. This enables a myriad of direct analyses, such as mapping atom column properties and correlating long-range atom column pairs. MATLAB source code can be downloaded from https://github.com/subangstrom/aci.

Psychosocial health effects of Covid-19 infection on persons in treatment centers in Lagos, Nigeria.

INTRODUCTION: Prior research has highlighted the psychosocial impact of infectious diseases on individuals and the community at large. However, little is known about the psychosocial implications of COVID-19. This study set out to determine the rate as well as correlates of anxiety and depressive symptoms among persons managed as in-patients for COVID-19 in Lagos, Nigeria. MATERIALS AND METHODS: We conducted an online survey between April to June ending 2020 using a consecutive sampling technique of persons positive for COVID-19 and who were managed as in-patients across five (5) treatment centres in Lagos, Nigeria. The survey collected information on demographic as well as clinical data including suicidality. Anxiety and depressive symptoms were assessed using the Hospital Anxiety and Depression Scale (HADS). RESULTS: There were one hundred and sixty participants in total. The mean age of respondents was 36.4 (±9.7) years with a higher proportion (56.9%) being males. With regards to diagnosis, 28.1% and 27.5% of the respondents were categorised as probable cases of depression and anxiety respectively, while 3.8% respondents reported suicidal ideation. Majority of the respondents (61.9%) reported the fear of infecting their loved ones. The variables that showed association with psychiatric morbidity were a past history of an emotional concern, employment status, guilt about infecting others and boredom. CONCLUSION: This study revealed a high burden of psychological/psychiatric morbidity among persons treated for COVID-19, particularly persons who have had prior emotional concerns. The findings from this study reiterate the need to pay attention to the mental health of people during disease outbreaks and to incorporate psychosocial interventions as part of the management package.

Airbrushed nickel nanoparticles for large-area growth of vertically aligned carbon nanofibers on metal (Al, Cu, Ti) surfaces.

Vertically aligned carbon nanofibers (VACNFs) were grown by plasma-enhanced chemical vapor deposition (PECVD) using Ni nanoparticle (NP) catalysts that were deposited by airbrushing onto Si, Al, Cu, and Ti substrates. Airbrushing is a simple method for depositing catalyst NPs over large areas that is compatible with roll-to-roll processing. The distribution and morphology of VACNFs are affected by the airbrushing parameters and the composition of the metal foil. Highly concentrated Ni NPs in heptane give more uniform distributions than pentane and hexanes, resulting in more uniform coverage of VACNFs. For VACNF growth on metal foils, Si micropowder was added as a precursor for Si-enriched coatings formed in situ on the VACNFs that impart mechanical rigidity. Interactions between the catalyst NPs and the metal substrates impart control over the VACNF morphology. Growth of carbon nanostructures on Cu is particularly noteworthy because the miscibility of Ni with Cu poses challenges for VACNF growth, and carbon nanostructures anchored to Cu substrates are desired as anode materials for Li-ion batteries and for thermal interface materials.