Highly efficient visible-light induced N-doped ZnO@g-C3N4 and S-doped ZnO@g-C3N4 photocatalysts for environmental remediation.

Facile, cost-effective and eco-friendly synthesis of N-doped ZnO@g-C3N4 and S-doped ZnO@g-C3N4 photocatalysts towards efficient degradation of environmental pollutants was achieved. The as-synthesized 2 wt% N-doped ZnO@g-C3N4 and 2 wt% S-doped ZnO@g-C3N4 achieved 96.2% and 90.4% degradation efficiencies towards crystal violet (100 ppm) within 45 min irradiation and 99.3% and 92.3% photocatalytic degradation efficiencies towards brilliant green (100 ppm) dye within 30 min irradiation, respectively, under a normal 90 W LED light instead of an expensive commercial light source. Moreover, the N-doped ZnO@g-C3N4 and S-doped ZnO@g-C3N4 nanocomposites showed excellent stability in the photodegradation of crystal violet and brilliant green dyes. The modification made on ZnO by doping with nitrogen and sulphur enhances the visible-light absorption as well as the separation of photoexcited charge carriers. The active radicals ˙OH and ˙O2- are both identified to play important roles in the photodegradation of crystal violet and brilliant green.

Understanding the barriers and facilitators of COVID-19 risk mitigation strategy adoption and COVID-19 vaccination in refugee settlements in Uganda: a qualitative study.

BACKGROUND: Perspectives on COVID-19 risk and the willingness and ability of persons living in refugee settlements to adopt COVID-19 prevention strategies have not been rigorously evaluated. The realities of living conditions in Ugandan refugee settlements may limit the extent to which refugees can uptake strategies to mitigate COVID-19 risk. METHODS: In-depth qualitative interviews were conducted between April 2021 and April 2022 to assess COVID-19 knowledge, risk perception, prevention strategy adoption including COVID-19 vaccination, and COVID-19 impact on living conditions in refugee settlements in Uganda. Interview participants included 28 purposively selected refugees who called into "Dial-COVID", a free telephone COVID-19 information collection and dissemination platform that was advertised in refugee settlements by community health workers. Interviews were analyzed using a combination of deductive and inductive content analysis. Emerging themes were mapped onto the Theoretical Domains Framework to identify domains influencing prevention behavior. Results were synthesized to provide intervention and policy recommendations for risk mitigation in refugee settlements for COVID-19 and future infectious disease outbreaks. RESULTS: The COVID-19 pandemic detrimentally impacted economic and food security as well as social interactions in refugee settlements. Youth were considered especially impacted, and participants reported incidents of child marriage and teenage pregnancy following school closures. Participants displayed general knowledge of COVID-19 and expressed willingness to protect themselves and others from contracting COVID-19. Risk mitigation strategy uptake including COVID-19 vaccination was influenced by COVID-19 knowledge, emotions surrounding COVID-19, the environmental context and resources, personal goals, beliefs about the consequences of (non)adoption, social influences, and behavior reinforcement. Resource constraints, housing conditions, and competing survival needs challenged the adoption of prevention strategies and compliance decreased over time. CONCLUSIONS: Contextual challenges impact the feasibility of COVID-19 risk mitigation strategy uptake in refugee settlements. Pre-existing hardships in this setting were amplified by the COVID-19 pandemic and related lockdowns. Targeted dispelling of myths, alignment of information across communication mediums, supporting survival needs and leveraging of respected role models are strategies that may hold potential to mitigate risk of infectious diseases in this setting. REGISTRATION DETAILS: World Pandemic Research Network - 490,652.

Leveraging interactive voice response technology to mitigate COVID-19 risk in refugee settlements in Uganda: Lessons learned implementing "Dial-COVID" a toll-free mobile phone symptom surveillance and information dissemination tool.

BACKGROUND: Persons living in refugee settlements in sub-Saharan Africa may be at increased risk for COVID-19 and experience barriers to accessing COVID-19 information. We aimed to evaluate the implementation of "Dial-COVID" a multi-lingual, toll free, telephone platform that uses interactive voice response (IVR) to track COVID-19 symptoms/exposure and disseminate COVID-19 health information in refugee settlements in Uganda. We hypothesized that IVR could provide an alternative way to screen for COVID-19 and communicate public health information to humanitarian populations when physical access and testing capacity were limited. METHODS: The Dial-COVID IVR platform was created in ten languages and advertised by community health workers in refugee settlements for participants to call into toll free. In a recorded IVR symptom survey, participants were screened for COVID-19 symptoms/exposures and based on their responses, received tailored public health messages about COVID-19 risk mitigation in accordance with Uganda Ministry of Health guidelines. Here we report the challenges and lessons learned implementing this research during the pandemic. RESULTS: Between February 2021 and March 2022, 15,465 calls were received by the Dial-COVID platform from all 31 refugee settlements in Uganda through which 6,913 symptom surveys were completed and 10,411 public health messages were disseminated in all study languages. Uptake of Dial-COVID fluctuated with the national COVID-19 caseload and was impacted by phone ownership and connectivity in refugee settlements. Intensified advertising efforts promoted Dial-COVID uptake. Flexibility to adapt IVR messages was contingent on translation capacity. CONCLUSION: Refugees living in refugee settlements across Uganda accessed Dial-COVID to share and obtain COVID-19 information suggesting that IVR holds potential for rapid information dissemination and screening of humanitarian populations during future infectious disease outbreaks and may be a valuable tool for routine public health programs. IVR adaptation flexibility and reach are influenced by language constraints and by contextual factors related to platform access. REGISTRATION DETAILS: World Pandemic Research Network- 490652.

Stable lead-halide perovskite quantum dots as efficient visible light photocatalysts for organic transformations.

Lead halide perovskite (LHP) based colloidal quantum dots (CQDs) have tremendous potential for photocatalysis due to their exceptional optical properties. However, their applicability in catalysis is restricted due to poor chemical stability and low recyclability. We report halide-passivated, monodisperse CsPbBr3CQDs as a stable and efficient visible-light photocatalyst for organic transformations. We demonstrate oxidative aromatization of a wide range of heterocyclic substrates including examples which are poor hydrogen transfer (HAT) reagents. Two to five-fold higher rate kinetics were observed for reactions catalyzed by CsPbBr3CQDs in comparison with bulk-type CsPbBr3 (PNCs) or conventionally synthesized CsPbBr3CQDs and other metal organic dyes (rhodamine 6G and [Ru(bpy)3]2+). Furthermore, these CQDs exhibit improved air-tolerance and photostability and in turn show a higher turnover number (TON) of 200, compared to conventionally prepared CQDs (TON = 166) and state-of-the-art bulk-type perovskite-based catalyst (TON = 177). Our study paves the way for the practical applicability of energy-level tunable, size-controlled LHP CQDs as efficient photocatalysts in organic synthesis.

Tunable NIR-II emitting silver chalcogenide quantum dots using thio/selenourea precursors: preparation of an MRI/NIR-II multimodal imaging agent.

Aqueous-stable, Cd- and Pb-free colloidal quantum dots with fluorescence properties in the second near-infrared region (NIR-II, 1000-1400) are highly desirable for non-invasive deep-tissue optical imaging and biosensing. The low band-gap semiconductor, silver chalcogenide, offers a non-toxic and stable alternative to existing Pd, As, Hg and Cd-based NIR-II colloidal quantum dots (QDs). We report facile access to NIR-II emission windows with Ag2X (X = S, Se) QDs using easy-to-prepare thio/selenourea precursors and their analogues. The aqueous phase transfer of these QDs with a high conservation of fluorescence quantum yield (retention up to ∼90%) and colloidal stability is demonstrated. A bimodal NIR-II/MRI contrast agent with a tunable fluorescence and high T1 relaxivity of 408 mM-1 s-1 per QD (size ∼ 2.2 nm) and 990 mM-1 s-1 per QD (size ∼ 4.2 nm) has been prepared by grafting 50 and 120 monoaqua Gd(iii) complexes respectively to two differently sized Ag2S QDs. The size of the nanocrystals is crucial for tuning the Gd payload and the relaxivity.