High‐performance thermal insulating aerogels are attractive candidates for thermal protection in extreme environments. However, inorganic aerogels’ brittleness and poor machinability limit their ...applications, while organic aerogels suffer from severe strength degradation and structural collapse at high temperatures. Herein, for the first time, a thermo‐responsive self‐ceramifiable aerogel is demonstrated with exceptional strengthening and thermal insulation at high temperatures. This aerogel exhibits excellent toughness and processability like polymers under normal conditions but spontaneously transforms into high‐strength semi‐crystalline hard ceramics upon exposure to high temperatures. After prolonged thermal attack at 800 °C, the strength of the aerogels does not decrease but significantly increases several‐fold (from 0.739 to 2.726 MPa). The self‐ceramization behavior and mechanism of the aerogel are illustrated in detail. The unique self‐ceramifiable capacity enables aerogels to provide fire resistance, high‐strength support, and excellent thermal insulation at ultrahigh temperatures. Even with continuous burning at 1300 °C for 60 min, the 15 mm thick aerogel shows low backside temperature below 300 °C, crack‐free overall structure, and invariant porous morphology. This self‐ceramifiable aerogel opens up a new avenue for developing thermal‐protection materials with toughness, machinability, high strength, and thermal insulation in extreme environments.
A new thermo‐responsive self‐ceramifiable aerogel is for the first time reported with exceptional strengthening and thermal insulation at high temperatures. Under normal conditions, the aerogel exhibits excellent toughness and machinability. Upon exposure to high temperatures, the aerogel spontaneously and rapidly transforms into robust semi‐crystalline hard ceramics, thus leading to fire resistance, high strength, and thermal insulation in extreme environments.
Adult hippocampal neurogenesis plays a critical role in memory and emotion processing, and this process is dynamically regulated by neural circuit activity. However, it remains unknown whether ...manipulation of neural circuit activity can achieve sufficient neurogenic effects to modulate behavior. Here we report that chronic patterned optogenetic stimulation of supramammillary nucleus (SuM) neurons in the mouse hypothalamus robustly promotes neurogenesis at multiple stages, leading to increased production of neural stem cells and behaviorally relevant adult-born neurons (ABNs) with enhanced maturity. Functionally, selective manipulation of the activity of these SuM-promoted ABNs modulates memory retrieval and anxiety-like behaviors. Furthermore, we show that SuM neurons are highly responsive to environmental novelty (EN) and are required for EN-induced enhancement of neurogenesis. Moreover, SuM is required for ABN activity-dependent behavioral modulation under a novel environment. Our study identifies a key hypothalamic circuit that couples novelty signals to the production and maturation of ABNs, and highlights the activity-dependent contribution of circuit-modified ABNs in behavioral regulation.
Nucleus accumbens (NAc) is involved in behaviors that depend on heightened wakefulness, but its impact on arousal remains unclear. Here, we demonstrate that NAc dopamine D1 receptor (D1R)-expressing ...neurons are essential for behavioral arousal. Using in vivo fiber photometry in mice, we find arousal-dependent increases in population activity of NAc D1R neurons. Optogenetic activation of NAc D1R neurons induces immediate transitions from non-rapid eye movement sleep to wakefulness, and chemogenetic stimulation prolongs arousal, with decreased food intake. Patch-clamp, tracing, immunohistochemistry, and electron microscopy reveal that NAc D1R neurons project to the midbrain and lateral hypothalamus, and might disinhibit midbrain dopamine neurons and lateral hypothalamus orexin neurons. Photoactivation of terminals in the midbrain and lateral hypothalamus is sufficient to induce wakefulness. Silencing of NAc D1R neurons suppresses arousal, with increased nest-building behaviors. Collectively, our data indicate that NAc D1R neuron circuits are essential for the induction and maintenance of wakefulness.
Sodium metal anodes are poor due to the reversibility of Na plating/stripping, which hinders their practical applications. A strategy to form a sodiophilic Au–Na alloy interphase on a Cu current ...collector, involving a sputtered Au thin layer, is shown to enable efficient Na plating/stripping for a certain period of time. Herein, electrochemical behaviors of Na plating on different substrates are explored, and it is revealed that the sodiophilic interphase can be achieved universally by in situ formation of M–Na (M = Au, Sn, and Sb) alloys during Na plating prior to Na bulk deposition in the initial cycle. Moreover, it is found that repetitive alloying–dealloying leads to falling‐off of thin film sodiophilic materials and thus limits the lifespan of efficient Na cycling. Therefore, an approach is further developed by employing particles of sodiophilic materials combined with the control over the cutoff potential, which significantly improves the stability of Na plating/stripping process. Especially, the low‐cost Cu@Sn‐NPs and Cu@Sb‐MPs composite current collectors allow Na plating and stripping to cycle for 2000 and 1700 times with the average efficiency of 99.9% at 2 mA cm−2.
Stable Na plating/stripping electrochemical behaviors are achieved by using the in situ formed sodiophilic sodium‐metal (metal = Au, Sn, Sb) alloy interphase. By simultaneous control over the stripping cut‐off potential and employment of anchored metal particles, Na plating/stripping cycling is extended to 2000 times at 2 mA cm−2 with an average Coulombic efficiency of 99.9% on the sodium‐metal alloy‐based interphase.
Disclosed herein is the first carbene‐organocatalyzed asymmetric addition of phosphine nucleophiles to the in situ generated α,β‐unsaturated acyl azolium intermediates. Our reaction ...enantioselectively constructs carbon–phosphine bonds and prepares chiral phosphines with high optical purities. The phosphine products are suitable for transforming to chiral ligands or catalysts with applications in asymmetric catalysis. The diarylalkyl or trialkyl phosphine products from our catalytic reactions, air‐sensitive and reactive in nature, can be trapped (and stored) in their sulfur‐oxidized form for operational simplicities.
Carbene‐catalyzed asymmetric addition of phosphorus atoms to α,β‐unsaturated acyl azolium intermediates affords chiral phosphines with potential applications as ligands and catalysts.
•UHPC jacket significantly improves compressive behaviors of stub concrete column.•UHPC jacket offers better confinements on circular concrete columns than square ones.•Analytical models predict well ...compressive behaviours of columns with UHPC jacket.•Developed FEM predicts well compressive behaviours of columns with UHPC jacket.
This paper firstly performed compressive tests on 18 stub concrete columns with externally confined ultra-high performance concrete (UHPC) jacket. The studied parameters in this testing programme were the thickness of UHPC jacket and the shapes of specimens. The influences of these parameters on the compressive behaviour of stub concrete columns confined by UHPC jacket were reported and discussed. The test results revealed that increasing the thickness of confining UHPC jacket significantly improved the compressive behaviours of concrete stub columns for cylindrical shaped column. However, this influence on that of square shaped stub columns was less significant. An analytical model was proposed to predict the compressive stress-strain behaviour of stub concrete columns with externally strengthening UHPC jacket. The validations of the predictions against the reported test results confirmed the accuracy of the analytical model. The compressive behaviour of stub concrete columns with UHPC jacket was also simulated by 3D nonlinear finite element model (FEM). Validations against the reported test data proved that the FEM simulated well compressive behaviour of concrete stub columns with UHPC jacket.
Hereditary cholestasis in childhood and infancy with normal serum gamma‐glutamyltransferase (GGT) activity is linked to several genes. Many patients, however, remain genetically undiagnosed. Defects ...in myosin VB (MYO5B; encoded by MYO5B) cause microvillus inclusion disease (MVID; MIM251850) with recurrent watery diarrhea. Cholestasis, reported as an atypical presentation in MVID, has been considered a side effect of parenteral alimentation. Here, however, we report on 10 patients who experienced cholestasis associated with biallelic, or suspected biallelic, mutations in MYO5B and who had neither recurrent diarrhea nor received parenteral alimentation. Seven of them are from two study cohorts, together comprising 31 undiagnosed low‐GGT cholestasis patients; 3 are sporadic. Cholestasis in 2 patients was progressive, in 3 recurrent, in 2 transient, and in 3 uncategorized because of insufficient follow‐up. Liver biopsy specimens revealed giant‐cell change of hepatocytes and intralobular cholestasis with abnormal distribution of bile salt export pump (BSEP) at canaliculi, as well as coarse granular dislocation of MYO5B. Mass spectrometry of plasma demonstrated increased total bile acids, primary bile acids, and conjugated bile acids, with decreased free bile acids, similar to changes in BSEP‐deficient patients. Literature review revealed that patients with biallelic mutations predicted to eliminate MYO5B expression were more frequent in typical MVID than in isolated‐cholestasis patients (11 of 38 vs. 0 of 13). Conclusion: MYO5B deficiency may underlie 20% of previously undiagnosed low‐GGT cholestasis. MYO5B deficiency appears to impair targeting of BSEP to the canalicular membrane with hampered bile acid excretion, resulting in a spectrum of cholestasis without diarrhea. (Hepatology 2017;65:1655‐1669).
Herein, a composite polymer electrolyte with a viscoelastic and nonflammable interface is designed to handle the contact issue and preclude Li dendrite formation. The composite polymer electrolyte ...(cellulose acetate/polyethylene glycol/Li1.4Al0.4Ti1.6P3O12) exhibits a wide electrochemical window of 5 V (vs Li+/Li), a high Li+ transference number of 0.61, and an excellent ionic conductivity of above 10−4 S cm−1 at 60 °C. In particular, the intimate contact, low interfacial impedance, and fast ion‐transport process between the electrodes and solid electrolytes can be simultaneously achieved by the viscoelastic and nonflammable layer. Benefiting from this novel design, solid lithium metal batteries with either LiFePO4 or LiCoO2 as cathode exhibit superior cyclability and rate capability, such as a discharge capacity of 157 mA h g−1 after 100 cycles at C/2 and 97 mA h g−1 at 5C for LiFePO4 cathode. Moreover, the smooth and uniform Li surface after long‐term cycling confirms the successful suppression of dendrite formation. The viscoelastic and nonflammable interface modification of solid electrolytes provides a promising and general strategy to handle the interfacial issues and improves the operative safety of solid lithium metal batteries.
A strategy to stabilize and improve the electrode–electrolytes interface, via a viscoelastic interface design, is developed. The viscoelastic and nonflammable ionic liquids interface can construct an effective Li+ transport pathway in the cathode and maintain the interface stability at both anode and cathode. This finding provides a practical and promising strategy for optimizing the solid electrolytes‐electrode interface.
The construction of liquid nitrogen gas storages and engineering structures in cold regions exposed reinforced concrete structures to low temperatures. This paper investigates the compressive ...strength of normal‐weight concrete under low temperatures to −165°C through a 174‐specimen test program. The key parameters studied in this test program included low temperature T ranging from −165 to +20°C, water/cement ratio ranging from 0.33 to 0.57, and water content Wc ranging from 0 to 6%. Their influences on the compressive strength of the concrete under low temperature were highlighted and analyzed. With the scanning electron microscope (SEM), the influence of these parameters on the microstructures of the concrete under low temperature was observed and presented. These test data and SEM analyses revealed the failure mechanism and provided proofs on the improvements of the compressive strength of the concrete under low temperature. Based on these test data, a mathematical model has developed to describe the relationship between the increasing factor of the compressive strength of the concrete under low temperatures and the influencing parameters of T, w/c ratio, and Wc. Finally, design equations are provided to predict the increasing factor of the compressive strength of the concrete under low temperature.
This review reports on the effects of fermentation on the chemical constituents and antioxidant activity of plant-based food materials. Fermentation involves a series of reactions that modify the ...chemical components of the substrate. It could be considered a tool to increase the bioactive compounds and functional properties of food plant materials. Oxidative damage is key to the progression of many human diseases, and the production of antioxidant compounds by fermentation will be helpful to reduce the risk of these diseases. Fermentation also can improve antioxidant activity given its association with increased phytochemicals, antioxidant polysaccharides, and antioxidant peptides produced by microbial hydrolysis or biotransformation. Additionally, fermentation can encourage the breakdown of plant cell walls, which helps to liberate or produce various antioxidant compounds. Overall, results indicated that fermentation in many cases contributed to enhancing antioxidants' content and antioxidant capacity, supporting the fermentation use in the production of value-added functional food. This review provides an overview of the factors that impact the effects of fermentation on bioactive compound composition and antioxidant activity. The impacts of fermentation are summarized as a reference to its effects on food plant material.
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