Search for: All records

Climate change is adversely impacting the burden of diarrheal diseases. Despite significant reduction in global prevalence, diarrheal disease remains a leading cause of morbidity and mortality among young children in low- and middle-income countries. Previous studies have shown that diarrheal disease is associated with meteorological conditions but the role of large-scale climate phenomena such as El Niño-Southern Oscillation (ENSO) and monsoon anomaly is less understood. We obtained 13 years (2002–2014) of diarrheal disease data from Nepal and investigated how the disease rate is associated with phases of ENSO (El Niño, La Niña, vs. ENSO neutral) monsoon rainfall anomaly (below normal, above normal, vs. normal), and changes in timing of monsoon onset, and withdrawal (early, late, vs. normal). Monsoon season was associated with a 21% increase in diarrheal disease rates (Incident Rate Ratios [IRR]: 1.21; 95% CI: 1.16–1.27). El Niño was associated with an 8% reduction in risk while the La Niña was associated with a 32% increase in under-5 diarrheal disease rates. Likewise, higher-than-normal monsoon rainfall was associated with increased rates of diarrheal disease, with considerably higher rates observed in the mountain region (IRR 1.51, 95% CI: 1.19–1.92). Our findings suggest that under-5 diarrheal disease burden in Nepal is significantly influenced by ENSO and changes in seasonal monsoon dynamics. Since both ENSO phases and monsoon can be predicted with considerably longer lead time compared to weather, our findings will pave the way for the development of more effective early warning systems for climate sensitive infectious diseases.

N‐Type thermoelectrics typically consist of small molecule dopant+polymer host. Only a few polymer dopant+polymer host systems have been reported, and these have lower thermoelectric parameters. N‐type polymers with high crystallinity and order are generally used for high‐conductivity () organic conductors. Few n‐type polymers with only short‐range lamellar stacking for high‐conductivity materials have been reported. Here, we describe an n‐type short‐range lamellar‐stacked all‐polymer thermoelectric system with highestof 78 S⁻¹, power factor (PF) of 163 μW m⁻¹ K⁻², and maximum Figure of merit (ZT) of 0.53 at room temperature with a dopant/host ratio of 75 wt%. The minor effect of polymer dopant on the molecular arrangement of conjugated polymer PDPIN at high ratios, high doping capability, high Seebeck coefficient (S) absolute values relative to, and atypical decreased thermal conductivity () with increased doping ratio contribute to the promising performance.

N‐Type thermoelectrics typically consist of small molecule dopant+polymer host. Only a few polymer dopant+polymer host systems have been reported, and these have lower thermoelectric parameters. N‐type polymers with high crystallinity and order are generally used for high‐conductivity () organic conductors. Few n‐type polymers with only short‐range lamellar stacking for high‐conductivity materials have been reported. Here, we describe an n‐type short‐range lamellar‐stacked all‐polymer thermoelectric system with highestof 78 S⁻¹, power factor (PF) of 163 μW m⁻¹ K⁻², and maximum Figure of merit (ZT) of 0.53 at room temperature with a dopant/host ratio of 75 wt%. The minor effect of polymer dopant on the molecular arrangement of conjugated polymer PDPIN at high ratios, high doping capability, high Seebeck coefficient (S) absolute values relative to, and atypical decreased thermal conductivity () with increased doping ratio contribute to the promising performance.

A novel n‐type copolymer dopant polystyrene–poly(4‐vinyl‐N‐hexylpyridinium fluoride) (PSpF) with fluoride anions is designed and synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. This is thought to be the first polymeric fluoride dopant. Electrical conductivity of 4.2 S cm^–1and high power factor of 67 µW m^–1K^–2are achieved for PSpF‐doped polymer films, with a corresponding decrease in thermal conductivity as the PSpF concentration is increased, giving the highest ZT of 0.1. An especially high electrical conductivity of 58 S cm^–1at 88 °C and outstanding thermal stability are recorded. Further, organic transistors of PSpF‐doped thin films exhibit high electron mobility and Hall mobility of 0.86 and 1.70 cm²V^–1s^–1, respectively. The results suggest that polystyrene–poly(vinylpyridinium) salt copolymers with fluoride anions are promising for high‐performance n‐type all‐polymer thermoelectrics. This work provides a new way to realize organic thermoelectrics with high conductivity relative to the Seebeck coefficient, high power factor, thermal stability, and broad processing window.