Red cell distribution width as a cardiovascular risk predictor in adults with hypertension in sub-Saharan Africa
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Anion vacancies activate N2 to ammonia on Ba–Si orthosilicate oxynitride-hydride
Anion vacancies on metal oxide surfaces have been studied as either active sites or promoting sites in various chemical reactions involving oxidation/reduction processes. However, oxide materials rarely work effectively as catalysts in the absence of transition metal sites. Here we report a Ba–Si orthosilicate oxynitride–hydride as a transition-metal-free catalyst for efficient ammonia synthesis via an anion-vacancy–mediated mechanism. The facile desorption of H− and N3− anions plus the flexibility of the crystal structure can accommodate a high density of electrons at vacancy sites, where N2 can be captured and directly activated to ammonia through hydrogenation processes. The ammonia synthesis rates reach 40.1 mmol g−1 h−1 at 300 °C by loading ruthenium nanoparticles. Although not found to dissociate N2, Ru instead facilitates the formation of anion vacancies at the Ru–support interface. This demonstrates a new route for anion-vacancy–mediated heterogeneous catalysis.
Synergistic proton conduction via Ca-vacancy coupled with Li+-bridge in Ca5(PO4)3OH
Proton conductivity plays a crucial role in the advancement of materials for proton ceramic fuel cells (PCFCs) and a variety of electrochemical devices. Traditional approaches to enhancing proton conductivity in perovskites have largely relied on doping strategies to induce structural oxygen vacancies. However, these methods have yet to overcome the challenges associated with achieving desired proton conductivity. Here, we introduce an approach wherein intermediate Li+ ions act as a bridge linked to Ca vacancies, fostering a mechanism for accelerated proton transport. Utilizing protonated Ca5(PO4)3OH-H(Li) as an electrolyte, we achieve a proton conductivity of 0.1 S cm−1 and a fuel cell performance of 661 mW cm−2 at an operational temperature of 550 °C for realizing low temperature PCFCs. This proton transport synergy overcomes traditional doping limitations, enabling the advancement of proton-conducting electrolytes and enhancing the efficiency of proton conducting electrolyte fuel cells, with implications in energy conversion and storage technologies.
Self-reported hypertension prevalence, risk factors, and knowledge among South Africans aged 24 to 40 years old
Although hypertension is a significant public health burden in South Africa (SA), less is known about its prevalence, risk factors, and possible preventative strategies among young adults. We assessed the prevalence, possible risk factors, and knowledge associated with self-reported hypertension among young adults from SA. A cross-sectional online survey was conducted among 1000 young South African adults (24–40 years; 51.0% women). We administered a socio-demographic questionnaire and collected information on measures of socio-economic status (SES) (e.g. asset wealth index), self-reported medical history, and lifestyle risk factors. Furthermore, a modified version of the hypertension evaluation of lifestyle and management questionnaire was used to assess participants’ hypertension knowledge. The overall prevalence of self-reported hypertension was 24.0%, with significant differences between women and men (27.5% and 20.4% respectively, p = 0.033). Only 16.8% of the respondents had good hypertension knowledge. There was a positive association between good knowledge of hypertension and being hypertensive (OR = 1.43 CI:1.23–3.12), monthly blood pressure check-ups (OR = 2.03 CI:1.78–3.23), knowing the side effects of uncontrolled blood pressure (OR = 1.28 CI:1.07–1.89) and having a biological mother with hypertension (OR = 1.79 CI:1.53–2.21). Being employed full-time (OR = 0.74 CI:0.69–0.80), having a higher SES (wealth index 4 (OR = 0.70 CI:0.59–0.97) and 5 (OR = 0.65 CI:0.48–0.81)), exercising 6 to 7 days per week (OR = 0.83 CI:0.71–0.94), and not consuming alcohol at all (OR = 0.73 CI:0.67–0.89), were all found to be protective against hypertension. The high hypertension prevalence, lack of hypertension knowledge, and reported risk factors among this group highlight the need for early robust preventative strategies to mitigate hypertension risk among this population.
Redox-active inverse crowns for small molecule activation
Cyclic crown ethers bind metal cations to form host–guest complexes. Lesser-known inverse crowns are rings of metal cations that encapsulate anionic entities, enabling multiple deprotonation reactions, often with unusual selectivity. Self-assembly of a cycle of metal cations around the multiply charged carbanion during the deprotonation reaction is the driving force for this reactivity. Here we report the synthesis of a pre-assembled inverse crown featuring Na+ cations and a redox-active Mg0 centre. Reduction of N2O followed by N2 release and subsequent encapsulation of O2− demonstrates its reduce-and-capture functionality. Calculations reveal that this essentially barrier-free process involves a rare N2O2− dianion, embedded in the metalla-cycle. The inverse crown can adapt itself for binding larger anions like N2O22− through a self-reorganization process involving ring expansion. The redox-active inverse crown combines the advantages of a strong reducing agent with anion stabilizing properties provided by the ring of metal cations, leading to high reactivity and selectivity.
Sub-minute synthesis and modulation of β/λ-MxTi3-xO5 ceramics towards accessible heat storage
Nearly 50% of global primary energy consumption is lost as low-temperature heat. λ-Ti3O5 holds promise for waste heat harvesting and reuse; however, achieving reversible phase transitions between its λ and β phases under accessible conditions remains a major challenge. Here, we proposed a simple laser method that incorporates element substitution for sub-minute synthesis (20–60 s) of λ-MxTi3-xO5 (M = Mg, Al, Sc, V, Cr, Mn, or Fe, 0.09 ≤ x ≤ 0.42). In particular, aluminum-substituted λ-AlxTi3-xO5 demonstrated the lowest energy barrier, with a transition pressure of 557 MPa and temperature of 363 K. Notably, compression of the (001) crystal plane could reduce the transition pressure to only 35–40 MPa, enabling the applicability of λ-AlxTi3-xO5 for wide applications in heat recovery and future lunar explorations.
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