Thermal energy storage offers enormous potential for a wide range of energy technologies. Phase-change materials offer state-of-the-art thermal storage due to high latent heat. However, spontaneous ...heat loss from thermally charged phase-change materials to cooler surroundings occurs due to the absence of a significant energy barrier for the liquid-solid transition. This prevents control over the thermal storage, and developing effective methods to address this problem has remained an elusive goal. Herein, we report a combination of photo-switching dopants and organic phase-change materials as a way to introduce an activation energy barrier for phase-change materials solidification and to conserve thermal energy in the materials, allowing them to be triggered optically to release their stored latent heat. This approach enables the retention of thermal energy (about 200 J g
) in the materials for at least 10 h at temperatures lower than the original crystallization point, unlocking opportunities for portable thermal energy storage systems.
Alloy design based on single-principal-element systems has approached its limit for performance enhancements. A substantial increase in strength up to gigapascal levels typically causes the premature ...failure of materials with reduced ductility. Here, we report a strategy to break this trade-off by controllably introducing high-density ductile multicomponent intermetallic nanoparticles (MCINPs) in complex alloy systems. Distinct from the intermetallic-induced embrittlement under conventional wisdom, such MCINP-strengthened alloys exhibit superior strengths of 1.5 gigapascals and ductility as high as 50% in tension at ambient temperature. The plastic instability, a major concern for high-strength materials, can be completely eliminated by generating a distinctive multistage work-hardening behavior, resulting from pronounced dislocation activities and deformation-induced microbands. This MCINP strategy offers a paradigm to develop next-generation materials for structural applications.
Arylazopyrazole derivatives based on four core structures (4pzMe, 3pzH, 4pzH, and 4pzH-F2) and functionalized with a dodecanoate group were demonstrated to store thermal energy in their metastable Z ...isomer liquid phase and release the energy by optically triggered crystallization at −30 °C for the first time. Three heat storage–release schemes were discovered involving different activation methods (optical, thermal, or combined) for generating liquid-state Z isomers capable of storing thermal energy. Visible light irradiation induced the selective crystallization of the liquid phase via Z-to-E isomerization, and the latent heat stored in the liquid Z isomers was preserved for longer than 2 weeks unless optically triggered. Up to 92 kJ/mol of thermal energy was stored in the compounds, demonstrating remarkable thermal stability of Z isomers at high temperatures and liquid-phase stability at temperatures below 0 °C.
Consumption of dietary fat is one of the key factors leading to obesity. High-fat diet (HFD)-induced obesity is characterized by induction of inflammation in the hypothalamus; however, the temporal ...regulation of proinflammatory markers and their impact on hypothalamic appetite-regulating neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons remains undefined.
Mice were injected with an acute lipid infusion for 24 h or fed a HFD over 8-20 weeks. Characterized mouse NPY/AgRP hypothalamic cell lines were used for in vitro experimentation. Immunohistochemistry in brain slices or quantitative real-time PCR in cell lines, was performed to determine changes in the expression of key inflammatory markers and neuropeptides.
Hypothalamic inflammation, indicated by tumor necrosis factor (TNF)-α expression and astrocytosis in the arcuate nucleus, was evident following acute lipid infusion. HFD for 8 weeks suppressed TNF-α, while significantly increasing heat-shock protein 70 and ciliary neurotrophic factor, both neuroprotective components. HFD for 20 weeks induced TNF-α expression in NPY/AgRP neurons, suggesting a detrimental temporal regulatory mechanism. Using NPY/AgRP hypothalamic cell lines, we found that palmitate provoked a mixed inflammatory response on a panel of inflammatory and endoplasmic reticulum (ER) stress genes, whereas TNF-α significantly upregulated IκBα, nuclear factor (NF)-κB and interleukin-6 mRNA levels. Palmitate and TNF-α exposure predominantly induced NPY mRNA levels. Utilizing an I kappa B kinase β (IKKβ) inhibitor, we demonstrated that these effects potentially occur via the inflammatory IKKβ/NF-κB pathway.
These findings indicate that acute lipid and chronic HFD feeding in vivo, as well as acute palmitate and TNF-α exposure in vitro, induce markers of inflammation or ER stress in the hypothalamic appetite-stimulating NPY/AgRP neurons over time, which may contribute to a dramatic alteration in NPY/AgRP content or expression. Acute and chronic HFD feeding in vivo temporally regulates arcuate TNF-α expression with reactive astrocytosis, which suggests a time-dependent neurotrophic or neurotoxic role of lipids.
This review illustrates various structural design principles for molecular solar thermal (MOST) energy storage materials based on photoswitches that operate under different conditions,
e.g.
solution ...state, neat liquid, and solid, or result in a solid-liquid phase transition during their photo-isomerization. The structural modifications of MOST compounds enable the formation of each phase, which also influences the important performance metrics of the photoactive energy materials: the energy storage density per molecule or gravimetric energy density. Other major optical and thermal properties are also modulated by the molecular designs and affect the energy storage period, efficiency of the system, and device structures that accommodate the solar energy storage in each form of the MOST compounds. The introduction of different strategies that enable the large density heat storage under specific phase conditions will help to facilitate the further development of efficient MOST systems that will be readily integrated to device-scale applications with a transformative impact on the renewable energy markets.
This review illustrates structural design principles for molecular solar thermal (MOST) energy storage materials based on photoswitches that operate in different phases or result in a solid-liquid phase transition during their photo-isomerization.
We report the design of photo-responsive organic phase change materials that can absorb filtered solar radiation to store both latent heat and photon energy
via
simultaneous phase transition and ...photo-isomerization. The activation of photo-switches by long wavelengths ≥530 nm in the visible light range at a low irradiance is achieved, in the absence of high-intensity light sources, by the
ortho
-substitution of azobenzene units. The facile transition from crystalline to liquid phase is enabled by appending an aliphatic group on the photochromic moiety. The sunlight-activated liquid phase exhibits an exceptionally long heat storage without crystallization for nearly two months, and the release of energy is triggered by a short irradiation at 430 nm. The successful demonstration of photo-controlled latent heat storage accomplished by solar irradiation opens a new horizon on solar energy harvesting by functional organic materials, as a complementary system to photocatalysts and photovoltaic materials.
Photo-responsive organic phase change materials that can absorb filtered solar radiation in the visible range to store both latent heat and photon energy are demonstrated.
Development of microbiota-directed foods (MDFs) that selectively increase the abundance of beneficial human gut microbes, and their expressed functions, requires knowledge of both the bioactive ...components of MDFs and the mechanisms underlying microbe-microbe interactions. Here, gnotobiotic mice were colonized with a defined consortium of human-gut-derived bacterial strains and fed different combinations of 34 food-grade fibers added to a representative low-fiber diet consumed in the United States. Bioactive carbohydrates in fiber preparations targeting particular Bacteroides species were identified using community-wide quantitative proteomic analyses of bacterial gene expression coupled with forward genetic screens. Deliberate manipulation of community membership combined with administration of retrievable artificial food particles, consisting of paramagnetic microscopic beads coated with dietary polysaccharides, disclosed the contributions of targeted species to fiber degradation. Our approach, including the use of bead-based biosensors, defines nutrient-harvesting strategies that underlie, as well as alleviate, competition between Bacteroides and control the selectivity of MDF components.
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•In vivo screen for fibers targeting specific human gut taxa in a defined community•Proteomics and forward genetics identify bioactive nutrients and their utilization•Interspecies competition controls the outcome of fiber-based microbiota manipulation•Artificial food particles as biosensors of community-wide glycan degradation
An in vivo approach that includes administration of artificial food particles explains mechanisms by which different human gut microbes utilize bioactive components of dietary fibers and paves a path towards the development of microbiota-directed foods that provide metabolic benefits to the host.
Observational properties of throat aurora are investigated in detail by using 7 year continuous auroral observations obtained at Yellow River Station (magnetic latitude 76.24°N). From our inspection, ...throat aurora is often observed under the condition of stripy diffuse aurora contacting with the persistent discrete auroral oval, and the long‐period throat aurora observations generally consist of intermittent subsequences of throat aurora brightening followed by poleward moving auroral form and throat aurora dimming. We also noticed that the orientation of throat aurora is aligned along the ionospheric convection flow, and its local time distribution shows clear dependence on the interplanetary magnetic field (IMF) By component. These observational results indicate that factors inside the magnetosphere may play important role on occurrence of throat aurora. We thus suggest that throat aurora may present the ionospheric signature of redistribution of reconnection rate on the magnetopause by cold magnetospheric plasma flowing into the reconnection site. In addition, we also found that the occurrence rate of throat aurora clearly decreases with increase of the IMF cone angle (arccos(|Bx|/B)), which is very similar with the occurrence rate of high‐speed jet (HSJ) observed in magnetosheath depending on the IMF cone angle. This is suggested as that the HSJs occurred outside the magnetosphere may also play important role for generation of throat aurora by triggering magnetopause reconnection or by direct impacting. Although further studies are needed to clarify how the throat auroras are generated in detail, the relevant observations about throat aurora have presented important implications on a variety open questions, such as distribution and generation of cold plasma structures in the outer magnetosphere, magnetopause deformation, and possible relation between HSJ and reconnection.
Key Points
Throat aurora always observed together with diffuse aurora indicate that the occurrence is affected by factors inside the magnetosphere
Occurrence rate of throat aurora decreasing with increase of the IMF cone angle implies that the occurrence is affected by outside factors
Occurrence of throat aurora is related with factors both inside and outside the magnetosphere
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