Lithium and oxygen adsorption at the b-MnO2 (110) surface

The adsorption and co-adsorption of lithium and oxygen at the surface of rutile-like manganese dioxide(b-MnO2), which are important in the context of Li–air batteries, are investigated using density functional theory. In the absence of lithium, the most stable surface of b-MnO2, the (110), adsorbs oxygen in the form of peroxo groups bridging between two manganese cations. Conversely, in the absence of excess oxygen, lithium atoms adsorb on the (110) surface at two different sites, which are both tricoordinated to surface oxygen anions, and the adsorption always involves the transfer of one electron from the adatom to one of the five-coordinated manganese cations at the surface, creating (formally) Li+ and Mn3+ species. The co-adsorption of lithium and oxygen leads to the formation of a surface oxide, involving the dissociation of the O2 molecule, where the O adatoms saturate the coordination of surface Mn cations and also bind to the Li adatoms. This process is energetically more favourable than the formation of gas-phase lithium peroxide (Li2O2) monomers, but less favourable than the formation of Li2O2 bulk. These results suggest that the presence of b-MnO2 in the cathode of a nonaqueous Li–O2 battery lowers the energy for the initial reduction of oxygen during cell discharge

The Thermal Agitated Phase Transitions on the Ti32 Nanocluster: a Molecular Dynamics Simulation Study

Molecular dynamics simulations were performed to investigate the stability with respect to increasing the simulated temperature from 300 to 2400 K of an isolated cluster composed of 32 titanium atoms. The interatomic interactions were modelled using Gupta potentials as implemented within the classical molecular dynamics simulation software DL_POLY. The radial distribution functions (RDF), diffusion coefficient, and density profiles were examined to study the structural changes as a function of temperature. It was found that the Ti32 nanocluster exhibits temperature structural transition. The icosahedron and pentagonal bi-pyramid structures were found to be the most dominant building block fragments. Deformation of the nanocluster was also measured by diffusion coefficient, and it was found that the Ti32 are mobile above the bulk melting point. The phase transitions from solid to liquid have been identified by a simple jump in the total energy curve, with the predicted melting temperature near the bulk melting point (1941.15 K). As expected, the RDF’s and density profile peaks decrease with increasing temperature

Living with systemic lupus erythematosus in South Africa: a bitter pill to swallow

Background Systemic lupus erythematosus (SLE) often has a profound negative impact on health-related quality of life (HRQoL). In the absence of any qualitative studies in sub-Saharan Africa, we undertook a study to explore living experiences, perceptions and unmet needs of South African patients with SLE. Methods Twenty-five women with SLE consented to participate in the study. They underwent individual in-depth interviews exploring their physical concerns, emotional health, sexual well-being and fertility. NVivo software was used for analysis. Results Participants were either of black ancestry or mixed racial ancestry, mainly indigent with only a quarter gainfully employed. Living with pain was the most common complaint, negatively impacting on activities of daily living (ADL), family expectations, social life, sleep and intimacy. Most participants expressed challenges of living with fatigue, and many felt their fatigue was misconstrued as being ‘simply lazy’. This pernicious fatigue had negative consequences on many facets of ADL, including caring for dependants, job sustainability and sexual well-being. All participants experienced low emotional states, often associated with suicidal ideations. Many experienced difficulties with fertility and childbearing and these were exacerbated in many instances by the pessimism of health care providers, resulting in confusion and depression. Physical disfigurements resulting from lupus-associated alopecia and rashes and corticosteroid-induced weight fluctuations were a major concern. These changes often affected self-image and libido, leading to strained personal relationships. Coping mechanisms that participants adopted included intense spiritual beliefs, ‘pushing through the difficult times’ and use of alternative therapies to relief symptoms was common. A poor understanding of SLE on the part of participant’s family and the community, coupled with the unpredictable course of the disease, exacerbated frustration and social exclusion. For most, limited income, lack of basic services, family dependencies, and comorbid diseases, such as human immune deficiency virus (HIV), exacerbated the daily negative SLE experiences. Conclusion In this study of mainly indigent South African women, SLE is associated with complex, chronic and challenging life experiences. The chronic relapsing and unpredictable nature of the disease, poor understanding and acceptance of SLE, compounded by a background of poverty, inadequate social support structures, negatively impact on a range of personal, social and vocational daily life experiences. Improved access to psychosocial services and SLE education might result in better outcomes. Trial registration (Ethics Project identification code: 275/2016 and M160633 registered 10 & 29 August 2016)

Materials modelling in the University of Limpopo

This article provides insights into building research capacity in computational modelling of materials at the University of Limpopo (UL), formerly University of the North, in South Africa, through a collaboration with a consortium of universities in the United Kingdom (UK) through the support of the National Research Foundation (NRF), formerly the Foundation for Research and Development, and the Royal Society (RS). A background that led to the choice of building research capacity at historically disadvantaged universities in South Africa, including the UL, is given. The modus operandi of the collaboration between the UL and several UK universities on computational modelling of materials is outlined, together with the scientific highlights that were achieved in themes of minerals, energy storage and alloy development. The capacity built in terms of human capital and institutions set up is shared, which is followed by a discussion of the continuing research activities after the formal NRF–RS collaboration ceased with more alignment to industrial applications with national and international support. We conclude by highlighting the success of the project in capacity-building and consolidating the Materials Modelling Centre with developments of high-performance computing in South Africa and the African continent. We comment on the lessons learned regarding successful capacity-building programmes

Thermodynamically accessible titanium clusters TiN, N = 2–32

We have performed a genetic algorithm search on the tight-binding interatomic potential energy surface (PES) for small TiN (N = 2–32) clusters. The low energy candidate clusters were further refined using density functional theory (DFT) calculations with the PBEsol exchange–correlation functional and evaluated with the PBEsol0 hybrid functional. The resulting clusters were analysed in terms of their structural features, growth mechanism and surface area. The results suggest a growth mechanism that is based on forming coordination centres by interpenetrating icosahedra, icositetrahedra and Frank–Kasper polyhedra. We identify centres of coordination, which act as centres of bulk nucleation in medium sized clusters and determine the morphological features of the cluster

The thermal agitated phase transitions on the Ti32 nanocluster: a molecular dynamics simulation study

Molecular dynamics simulations were performed to investigate the stability with respect to increasing the simulated temperature from 300 to 2400 K of an isolated cluster composed of 32 titanium atoms. The interatomic interactions were modelled using Gupta potentials as implemented within the classical molecular dynamics simulation software DL_POLY. The radial distribution functions (RDF), diffusion coefficient, and density profiles were examined to study the structural changes as a function of temperature. It was found that the Ti32 nanocluster exhibits temperature structural transition. The icosahedron and pentagonal bi-pyramid structures were found to be the most dominant building block fragments. Deformation of the nanocluster was also measured by diffusion coefficient, and it was found that the Ti32 are mobile above the bulk melting point. The phase transitions from solid to liquid have been identified by a simple jump in the total energy curve, with the predicted melting temperature near the bulk melting point (1941.15 K). As expected, the RDF's and density profile peaks decrease with increasing temperatur

Sexually transmitted infection screening to prevent adverse birth and newborn outcomes: study protocol for a randomized-controlled hybrid-effectiveness trial

Background Sexually transmitted infections (STIs) during pregnancy are associated with adverse birth outcomes, including preterm birth, low birth weight, perinatal death, and congenital infections such as increased mother-to-child HIV transmission. Prevalence of STIs among pregnant women in South Africa remains high, with most women being asymptomatic for their infection(s). Unfortunately, most STIs remain undetected and untreated due to standard practice syndromic management in accordance with World Health Organization (WHO) guidelines. Although lab-based and point-of-care molecular tests are available, optimal screening strategies during pregnancy, their health impact, and cost-effectiveness are unknown. Methods We will implement a 3-arm (1:1:1) type-1 hybrid effectiveness-implementation randomized-controlled trial (RCT). We will enroll 2500 pregnant women attending their first antenatal care (ANC) visit for their current pregnancy at participating health facilities in Buffalo City Metro District, Eastern Cape Province, South Africa. Participants allocated to arms 1 and 2 (intervention) will receive GeneXpert® point-of-care diagnostic testing for Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis, with same-day treatment for detected infection(s). Arm 1 will additionally receive a test-of-cure 3 weeks post-treatment, while Arm 2 will receive a repeat test at 30–34 weeks’ gestation. Those allocated to Arm 3 will receive syndromic management (standard-of-care). The RE-AIM framework will be used to guide collection of implementation indicators to inform potential future scale up. Primary outcome measures include (1) frequency of adverse birth outcomes among study arms, defined by a composite measure of low birth weight and pre-term delivery, and (2) change in STI prevalence between baseline and birth outcome among intervention arms and compared to standard-of-care. Estimates and comparative costs of the different screening strategies relative to standard-of-care and the costs of managing adverse birth outcomes will be calculated. Cost-effectiveness will be assessed per STI and disability-adjusted life year averted. Discussion This trial is the first RCT designed to identify optimal, cost-effective screening strategies that decrease the burden of STIs during pregnancy and reduce adverse birth outcomes. Demonstrating the impact of diagnostic screening and treatment, compared to syndromic management, on birth outcomes will provide critical evidence to inform changes to WHO guidelines for syndromic management of STIs during pregnancy. Trial registration ClinicalTrials.gov NCT04446611 . Registered on 25 June 2020

Technology and implementation science to forge the future of evidence-based psychotherapies: the PRIDE scale-up study

Objective: To report the interim results from the training of providers in evidence-based psychotherapies (EBPs) and use of mobile applications. Design and setting: The Partnerships in Research to Implement and Disseminate Sustainable and Scalable Evidence (PRIDE) study is a cluster-randomised hybrid effectiveness-implementation trial comparing three delivery pathways for integrating comprehensive mental healthcare into primary care in Mozambique. Innovations include the use of EBPs and scaling-up of task-shifted mental health services using mobile applications. Main outcome measures: We examined EBP training attendance, certification, knowledge and intentions to deliver each component. We collected qualitative data through rapid ethnography and focus groups. We tracked the use of the mobile applications to investigate early reach of a valid screening tool (Electronic Mental Wellness Tool) and the roll out of the EBPs PARTICIPANTS: Psychiatric technicians and primary care providers trained in the EBPs. Results: PRIDE has trained 110 EBP providers, supervisors and trainers and will train 279 community health workers in upcoming months. The trainings improved knowledge about the EBPs and trainees indicated strong intentions to deliver the EBP core components. Trained providers began using the mobile applications and appear to identify cases and provide appropriate treatment. Conclusions: The future of EBPs requires implementation within existing systems of care with fidelity to their core evidence-based components. To sustainably address the vast mental health treatment gap globally, EBP implementation demands: expanding the mental health workforce by training existing human resources; sequential use of EBPs to comprehensively treat mental disorders and their comorbid presentations and leveraging digital screening and treatment applications. Keywords: adult psychiatry; anxiety disorders; depression & mood disorders; schizophrenia & psychotic disorders; substance misuse. © Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ

Spectroscopic and computer modelling studies of mixed-cation superionic fluorites

Mixed-cation superionic fluorites are exceptionally good F- ion conductors due to the mixed nature of the cation sublattice. In this study, we have used extended x-ray absorption fine structure (EXAFS) spectroscopy to gain insights into the local environments of the Cd and Pb cations (as a function of composition and temperature) in CdF2 (xPbF(2)) mixed-cation superionic fluorites. A high degree of disorder is shown around both cations. However, the extent of disorder is even larger around the Pb2+ in the entire series of solid solutions, with the highest disorder noted for the x = 60 mol% PbF2 sample. The large values of the Debye-Waller factors of the Pb-F interactions are consistent with the low amplitudes of their Fourier transforms. This can be correlated with relative ionic conductivities of each composition in these materials. Molecular dynamics (MD) has been used as a complementary technique on structural properties; systems were modelled at temperatures ranging from liquid nitrogen temperature, 77 K, to 300 K. Our MD results confirm that disorder is greatest at concentrations x approximate to 60 mol% PbF2