Explore the vast range of titles available.

Shilu Tong and colleagues describe the health consequences of extreme urban heat and the priorities for action and research to mitigate the harms

The contradiction between high piezoelectricity and uniquely poor temperature stability generated by polymorphic phase boundary is a huge obstacle to high-performance (K, Na)NbO 3 -based ceramics entering the application market as Pb-based substitutes. We possess the phase boundary by mimicking Pb(Zr, Ti)O 3 ’s morphotropic phase boundary structure via the synergistic optimization of diffusion phase boundary and crystal orientation in 0.94(Na 0.56 K 0.44 )NbO 3 −0.03Bi 0.5 Na 0.5 ZrO 3 −0.03(Bi 0.5 K 0.5 )HfO 3 textured ceramics. As a result, a prominent comprehensive performance is obtained, including giant d 33 of 550 ± 30 pC/N and ultrahigh temperature stability ( d 33 change rate less than 1.2% within 25-150 °C), representing a significant breakthrough in lead-free piezoceramics, even surpassing the Pb-based piezoelectric ceramics. Within the same temperature range, the d 33 change rate of the commercial Pb(Zr, Ti)O 3 −5 ceramics is only about 10%, and more importantly, its d 33 (~ 350 pC/N) is much lower than that of the (K, Na)NbO 3 -based ceramics in this work. This study demonstrates a strategy for constructing the phase boundary with MPB feature, settling the problem of temperature instability in (K, Na)NbO 3 -based ceramics. The authors induce a phase boundary similar to Pb(Zr, Ti)O 3 ’s morphotropic phase boundary structure in (K, Na)NbO 3 -based ceramics, which exhibit high residual polarization as well as a significantly improved piezoelectric constant d 33 .

Over the tropics, a robust statistical relationship between outgoing longwave radiation ( R ) and precipitation ( P ) is observed, linked to the cloud-radiative effect (CRE). To quantify this R – P relation, we define the CRE parameter, which exhibits significant disparities across global climate models (GCMs), with most overestimating it relative to the observation. Given the strong correlation between the CRE parameter and both historical and future extreme precipitation, an emergent constraint on the hydrological cycle projection is constructed. It lowers the fractional increase in the 99.9th percentile of tropical precipitation by the end of the 21st century from 29% to 24% under the high-emission warming scenario, with a 58% reduction in uncertainty. Overall, GCMs tend to underestimate the intensity of tropical extreme precipitation while overestimating its fractional increase. These findings provide valuable insights for model evaluation, improvement, and climate adaptation strategies.

Microbial ecosystem comprises a complex community in which bacteria interact with each other. The potential roles of the intestinal microbiome play in human health have gained considerable attention. The imbalance of gut microbial community has been looked to multiple chronic diseases. Cardiovascular diseases (CVDs) are leading causes of morbidity worldwide and are influenced by genetic and environmental factors. Recent advances have provided scientific evidence that CVD may also be attributed to gut microbiome. In this review, we highlight the complex interplay between microbes, their metabolites, and the potential influence on the generation and development of CVDs. The therapeutic potential of using intestinal microbiomes to treat CVD is also discussed. It is quite possible that gut microbes may be used for clinical treatments of CVD in the near future.

Ferroelectric polymer-based electrocaloric effect may lead to sustainable heat pumps and refrigeration owing to the large electrocaloric-induced entropy changes, flexible, lightweight and zero-global warming potential. Herein, low-k nanodiamonds are served as extrinsic dielectric fillers to fabricate polymeric nanocomposites for electrocaloric refrigeration. As low-k nanofillers are naturally polar-inactive, hence they have been widely applied for consolidate electrical stability in dielectrics. Interestingly, we observe that the nanodiamonds markedly enhances the electrocaloric effect in relaxor ferroelectrics. Compared with their high-k counterparts that have been extensively studied in the field of electrocaloric nanocomposites, the nanodiamonds introduces the highest volumetric electrocaloric enhancement (~23%/vol%). The resulting polymeric nanocomposite exhibits concurrently improved electrocaloric effect (160%), thermal conductivity (175%) and electrical stability (125%), which allow a fluid-solid coupling-based electrocaloric refrigerator to exhibit an improved coefficient of performance from 0.8 to 5.3 (660%) while maintaining high cooling power (over 240 W) at a temperature span of 10 K. Low-k nanodiamonds are discovered to possess the ability to concurrently enhance the electrocaloric effect, thermal conductivity, and electrical stability of polymeric nanocomposites, providing support for electrocaloric refrigeration.

The development of high-performance lead-free K 0.5 Na 0.5 NbO 3 -based piezoceramics for replacing commercial lead-containing counterparts is crucial for achieving environmentally sustainable society. Although the proposed new phase boundaries (NPB) can effectively improve the piezoelectricity of KNN-based ceramics, the difficulty of achieving saturated poling and the underlying multiscale structures resolution of their complex microstructures are urgent issues. Here, we employ a medium entropy strategy to design NPB and utilize texture engineering to induce crystal orientation. The developed K 0.5 Na 0.5 NbO 3 -based ceramics enjoys both prominent piezoelectric performance and satisfactory Curie temperature, thus exhibiting an ultrahigh energy harvesting performance as well as excellent transducer performance, which is highly competitive in both lead-free and lead-based piezoceramics. Comprehensive structural analysis have ascertained that the field-induced efficient multiscale polarization configurations irreversible transitions greatly encourages high saturated poling. This study demonstrates a strategy for designing high-performance piezoceramics and establishes a close correlation between the piezoelectricty and the underlying multiscale structures. There are difficulty of achieving saturated poling and understanding of multi-scale structures in (K, Na)NbO 3 ceramics. Here, the authors find atomic-scale polymorphic distortion and micrometer-scale high-density thin striped domains, which is key for high saturated poling.

Despite the extraordinary electromechanical properties of relaxor ferroelectrics, correlating their properties to underlying atomic-scale structures remains a decisive challenge for these “mess” systems. Here, taking the lead-free relaxor ferroelectric Bi 0.5 Na 0.5 TiO 3 -based system as an example, we decipher the atomic-scale structure and its relationship to the polar structure evolution and large dynamic electromechanical response, using the direct atomic-scale point-by-point correlation analysis. With judicious chemical modification, we demonstrate the increased defect concentration is the main driving force for deviating polarizations with high-angle walls, leading to the increased random field. Meanwhile, the main driving force for deviating polarizations with low-angle walls changes from the anti-phase oxygen octahedral tilting to the multidirectional A-O displacement, leading to the decreased anisotropy field. Benefiting from the competitive and synergetic equilibrium of anisotropic field versus random field, the facilitated polarization rotation and extension versus facilitated domain switching are identified to be responsible for the giant electromechanical response. These observations lay a foundation for understanding the “composition-structure-property” relationships in relaxor ferroelectric systems, guiding the design of functional materials for electromechanical applications. For relaxor ferroelectrics, correlating their properties and local structures is challenging. Here, the authors correlate the atomic-scale structure and the large dynamic electromechanical property in Bi 0.5 Na 0.5 TiO 3 -based relaxor ferroelectrics.

(K,Na)NbO 3 -based ceramics are deemed among the most promising lead-free piezoelectric materials, though their overall piezoelectric performance still lags behind the mainstream lead-containing counterparts. Here, we achieve an ultrahigh piezoelectric charge coefficient d 33 ∼ 807 pC·N −1 , along with a high longitudinal electromechanical coupling factor (k 33  ∼ 88%) and Curie temperature (T c  ∼ 245 °C) in the (K,Na)(Nb 1- x Sb x )O 3 -Bi 0.5 Na 0.5 ZrO 3 -BiFeO 3 (KNN- x Sb) system through structural flexibility and grain orientation strategies. Phenomenological models, phase field simulations and high-angle annular dark-field scanning transmission electron microscopy reveal that the structural flexibility originates from the high Coulomb force between K + /Na + ions and Sb ions in the KNN- x Sb system, while the grain orientation promotes the displacement of B-site cations leveraging the engineered domain configuration. As a result of its excellent comprehensive piezoelectric properties, the textured KNN-5Sb/epoxy 1-3 piezoelectric composite is found to possess a broader bandwidth BW = 60% and higher amplitude output voltage than commercial PZT-5 and other KNN counterparts. These findings suggest that the textured KNN-5Sb ceramics could potentially replace current lead-based piezoceramics in transducer applications. The authors achieve piezoelectric coefficient d 33 ∼ 807 pC·N −1 , along with high k 33 ∼ 88 % and T c ∼ 245 °C in (K,Na)(Nb 1- x Sb x )O 3 -Bi 0.5 Na 0.5 ZrO 3 -BiFeO 3 system through structural flexibility and grain orientation strategies.

Relaxor antiferroelectrics are considered promising candidate materials for achieving excellent energy storage capabilities. However, the trade-off between high recoverable energy density and high efficiency remains a major challenge in relaxor antiferroelectrics for practical applications. Herein, guided by phase-field simulation, we propose a strategy of designing polymorphic heterogeneous shell in core-shell dual-phase dielectrics to synergistically control micro and local heterostructures, resulting in comprehensive improvements in breakdown electric field, polarization fluctuation and saturation behaviors. Leveraging the core-shell effect and polarization heterogeneity, an ultrahigh recoverable energy density of 12.7 J cm -3 and an impressive efficiency of 87.2% are achieved in lead-free relaxor antiferroelectrics, making a performance breakthrough in core-shell dielectrics. This work opens up a new avenue to efficiently develop high-performance energy storage dielectrics and is expected to be popularized in other fields. The authors propose a polymorphic heterogeneous shell strategy to design core-shell dual-phase dielectrics through synergistically controlling micro and local scale heterostructures, resulting in excellent overall energy storage performance.

Cloud radiative effect (CRE) is crucial for the development of tropical cyclones (TCs). This study investigates the impact of cloud radiation on TC seeds and TCs in an aquaplanet model by tuning ‘threshold diameter to convert cloud ice particles to snow’ (DCS). With increased cloud cover associated with higher DCS, seed frequency decreases, but the greater intensity increase of seeds leads to a higher survival rate from seeds to TCs. The changes in large-scale circulation within the models are responsible for the reduced seed frequency. Higher DCS enhances equatorial cloud liquid and ice amounts, thereby intensifying radiation heating to the tropics. Increased radiation leads to more moisture and higher temperatures at high levels and increases the temperature gradient from the tropics to the subtropics, thereby intensifying the Hadley circulation. The resulting decrease in convective available potential energy and intensification of vertical wind shear act as inhibiting factors for seed genesis. Besides, the presence of more high-level clouds accumulates both longwave and shortwave heating, creating favorable thermal conditions for the circulation to develop at the mesoscale. This process supports the growth of seeds into mature TCs, resulting in higher survival rates from seeds to TCs. The findings on TCs and CRE in aquaplanet models could serve as a foundation and provide evidence for studies conducted in more complex environmental conditions.