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Insect gut microbiota and their metabolites play a significant role in the shaping of hosts' diets and feeding habits. We conducted 16S rDNA amplicon sequencing on the gut microbiota of specialist blister beetle larvae that feed on locust eggs and artificial food at different instars, to explore the relationship between gut microbiota and the specialized feeding habit of the blister beetle larvae. There is no significant difference in the gut microbial structure among the second to the fourth instar larvae under the same rearing conditions, but the gut microbial structure of the first instar larvae was significantly different from the second to the fourth instar larvae fed by different diets. Bacteria associated with polysaccharide utilization are relatively barren in first instar larvae. Compared to the carbohydrate content between the artificial diet and locust eggs, we speculate that an excessive amount of polysaccharides in the artificial diet may be detrimental to the growth and development of first instar larvae. Gut microbiota of the second to the fourth instar larvae fed with different diets significantly differ in microbial community structure. The different bacteria, especially the metabolism‐related intestinal bacteria in locust eggs‐fed larvae, may help the hosts adapt to the environment and contribute to the production of active ingredients. The relative abundance of polysaccharide utilization‐related bacteria was significantly higher in the artificial diet‐fed larvae compared to the locust eggs‐fed larvae, which showed the same result when compared to the first instar larvae. Changes in gut microbes of blister beetle larvae and their metabolic inferences could enrich our understanding of the nutritional requirements of the specialist and help optimize the artificial diet of medicinal cantharides. [ABSTRACT FROM AUTHOR]

Finding parent thermoelectric materials with a high figure of merit is a direction that people pursue. However, the interplay and constraints among the Seebeck coefficient, electrical conductivity, and thermal conductivity pose formidable challenges. In this review, the decoupling effect of anisotropic electronic energy band and multi‐valley band structures are initially introduced on the Seebeck coefficient and electrical conductivity. Subsequently, an overview of how materials with a host‐guest structure enable the coexistence of high electrical conductivity and low thermal conductivity through unique transport mechanisms is provided. Finally, deliberating on approaches to achieve intrinsic low lattice thermal conductivity, encompassing low dimensionality, low phonon group velocities, and substantial anharmonicity. Moreover, a detailed analysis is conducted to dissect the physical mechanisms through which strong higher‐order anharmonicity restricts lattice thermal transport. It is believed that this review serves as a guiding resource for the quest for and design of efficient thermoelectric materials. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of RbBaX (X = Sb, Bi), an anisotropic material with strong anharmonicity, are systematically studied by first-principles calculations, combined with the self-consistent phonon theory and the Boltzmann transport equation. A reasonable lattice thermal conductivity κL is captured by fully handling the phonon frequency shift and four-phonon scattering caused by the quartic anharmonicity. The κL of RbBaSb and RbBaBi along the a-axis is only 0.60 and 0.36 W m−1 K−1 at 300 K, respectively, which is much lower than that of most thermoelectric materials. The low phonon group velocity resulting from the unusually weak atomic bonding strengths along the a-axis is the origin of the ultralow κL. Furthermore, the high dispersion near the conduction band minimum enables n-type doping with a higher electrical conductivity. The results show that orthorhombic RbbaBi has a ZT as high as 1.04 at 700 K along the a-axis direction, indicating its great application potential in the thermoelectric field. [ABSTRACT FROM AUTHOR]

Pederin, a defensive toxin in Paederus fuscipes, is produced by an uncultured Gram‐negative symbiont, which establishes a stable symbiotic relationship with a female host before completion of metamorphosis. However, the transmission process of pederin‐producing bacteria (PPB) in P. fuscipes at different life stages remains unknown. Herein, the PPB population dynamics and transcriptome atlas for P. fuscipes development (egg, first‐instar larva, second‐instar larva, pupa, and newly emerged female and male) were characterised. We found that a microbial layer containing PPB covered the eggshell, which could be sterilised by smearing the eggshell with streptomycin. Maternal secretions over the eggshell are likely the main PPB acquisition route for P. fuscipes offspring. The PPB density in eggs was significantly higher than that in other life stages (p < 0.05), which demonstrated that the beetle mothers gave more PPB than the larvae acquired. Physiological changes (hatching and eclosion) led to a decreased PPB density in P. fuscipes. Pattern recognition receptors related to Gram‐negative bacteria recognition were identified from P. fuscipes transcriptomes across various life stages, which might be used to screen genes involved in PPB regulation. These results will help advance future efforts to determine the molecular mechanisms of PPB colonisation of P. fuscipes. [ABSTRACT FROM AUTHOR]

The thermal transport and thermoelectric characteristics of the chalcogenide XAgSe2 (X = Sc, Y) are comprehensively investigated through first-principles calculations. To treat the quartic anharmonicity completely, which encompasses four-phonon scattering and temperature-driven phonon frequency shift, the Boltzmann transport equation is solved on top of self-consistent phonon theory. Our investigation reveals that the soft X–Ag bond and the resonant bond in the pseudocage composed of X and Se atoms lead to ultralow lattice thermal conductivity. Moreover, the multi-valley electronic band structure displays good dispersion and high degeneracy, resulting in high power factors. Remarkably, p-type YAgSe2 captures zT values of 3.70 at 900 K, breaking the long-standing record for zT < 3. The results show that these materials have great potential for thermoelectric applications. [ABSTRACT FROM AUTHOR]

State-of-the-art first-principles calculations are performed to investigate the thermoelectric transport properties in thallium-based fluoride perovskites TlXF3 (X = Hg, Sn, Pb) by considering anharmonic renormalization of the phonon energy and capturing reasonable electron relaxation times. The lattice thermal conductivity, κL, of the three compounds is very low, among which TlPbF3 is only 0.42 W m−1 K−1 at 300 K, which is less than half of that of quartz glass. The low acoustic mode group velocity and strong three-phonon scattering caused by the strong anharmonicity of the Tl atom are the origin of the ultralow κL. Meanwhile, the strong ionic bonds between X (X = Hg, Sn, Pb) and F atoms provide good electrical transport properties. The results show that the ZT value of TlHgF3 at 900 K is 1.58, which is higher than the 1.5 value of FeNbSb at 1200 K. TlSnF3 and TlPbF3 also exceed 1, which is close to the classical thermoelectric material PbTe:Na. Furthermore, we present the methods and expected effects of improving the ZT value through nanostructures. [ABSTRACT FROM AUTHOR]

Pederin, a group of antitumor compounds, is produced by an endosymbiotic bacterium of Paederus fuscipes. Pederin content differed between male and female P. fuscipes, but the reason why these differences are maintained remains unexplored. Here, the pederin‐producing bacteria (PPB) infection rate in P. fuscipes was investigated. Furthermore, we assessed the microbiota structure differences in male and female P. fuscipes harbouring PPB and sequenced the transcriptome of both sexes to shed light on genes of interest. Of the 625 analysed beetles (275 females, 350 males), 96.36% of females and 31.14% of males were positive for PPB infection. PPB accounted for 54.36%–82.70% of the bacterial population in females but showed a much lower abundance in males (0.92%–3.87%). Reproductive organs possessed the highest PPB abundance compared with other parts of females, but no such relationships existed in males. Moreover, we provide the first transcriptome analysis of male and female P. fuscipes harbouring PPB and identified 8893 differentially expressed unigenes. Our results indicated that the pederin content difference between males and females might be caused by the PPB density difference in hosts. The biosequence data would be helpful for illustrating the mechanism that regulates PPB density in P. fuscipes. [ABSTRACT FROM AUTHOR]

State-of-the-art first-principles calculations are performed to investigate the thermoelectric transport properties in thallium-based fluoride perovskites TlXF 3 (X = Hg, Sn, Pb) by considering anharmonic renormalization of the phonon energy and capturing reasonable electron relaxation times. The lattice thermal conductivity, κ L , of the three compounds is very low, among which TlPbF 3 is only 0.42 W m -1 K -1 at 300 K, which is less than half of that of quartz glass. The low acoustic mode group velocity and strong three-phonon scattering caused by the strong anharmonicity of the Tl atom are the origin of the ultralow κ L . Meanwhile, the strong ionic bonds between X (X = Hg, Sn, Pb) and F atoms provide good electrical transport properties. The results show that the ZT value of TlHgF 3 at 900 K is 1.58, which is higher than the 1.5 value of FeNbSb at 1200 K. TlSnF 3 and TlPbF 3 also exceed 1, which is close to the classical thermoelectric material PbTe:Na. Furthermore, we present the methods and expected effects of improving the ZT value through nanostructures.