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Most of the state-of-the-art thermoelectric materials are inorganic semiconductors. Owing to the directional covalent bonding, they usually show limited plasticity at room temperature1,2, for example, with a tensile strain of less than five per cent. Here we discover that single-crystalline Mg3Bi2shows a room-temperature tensile strain of up to 100 per cent when the tension is applied along the (0001) plane (that is, the abplane). Such a value is at least one order of magnitude higher than that of traditional thermoelectric materials and outperforms many metals that crystallize in a similar structure. Experimentally, slip bands and dislocations are identified in the deformed Mg3Bi2, indicating the gliding of dislocations as the microscopic mechanism of plastic deformation. Analysis of chemical bonding reveals multiple planes with low slipping barrier energy, suggesting the existence of several slip systems in Mg3Bi2. In addition, continuous dynamic bonding during the slipping process prevents the cleavage of the atomic plane, thus sustaining a large plastic deformation. Importantly, the tellurium-doped single-crystalline Mg3Bi2shows a power factor of about 55 microwatts per centimetre per kelvin squared and a figure of merit of about 0.65 at room temperature along the abplane, which outperforms the existing ductile thermoelectric materials3,4.

Low-dimensional metal halide perovskites are widely studied due to their excellent optoelectronic properties and environmental stability. Recently, transition metal Mn2+ions were introduced into two-dimensional (2D) perovskite to modify their photophysical properties. However, the Mn luminescence mechanism still needs further exploration, which includes the role played by the A-site cation engineering. Herein, we prepared 2D perovskite microcrystals with four A-site cations: butylamine (BA), phenethylamine (PEA), octylamine (OCA) and oleylamine (OAM) by hot-injection method, namely Mn2+:BA2PbBr4, Mn2+:PEA2PbBr4, Mn2+:OCA2PbBr4, and Mn2+:OAM2PbBr4. The Mn PL lifetime is tuned from 0.12 to 0.75 ms, achieving a maximum PL QY of 83% in BA-based 2D perovskite. The obtained perovskite samples exhibited micrometer-sized morphology, and the periodic arrangement of X-ray diffraction demonstrated the formation of a single-layer 2D structure. The temperature-dependent PL spectra revealed that the enhancement mechanism of Mn emission was related to short-chain ligand surface passivation (BA and PEA) and improvement of the exciton-to-Mn2+energy transfer. The experimental results indicate that A-site cation engineering enriches the diversity of Mn-doped low-dimensional perovskites, which provides a new approach to regulate Mn luminescence kinetics.

Ion migration and phase separation in perovskite materials have negatively affected the solid-state lighting and display. Studying photo- and thermal-induced degradation is considered as a promising approach to understanding the luminescence mechanism and promoting practical applications. Herein, the Mn-doped two-dimensional PEA2PbX4(X = Cl, Br, I) microcrystals with changing halogen composition were synthesized by an acid-assisted post-processing strategy. Then, photo- and thermal-induced degradation was studied by using steady-state and time-resolved photoluminescence (PL) spectroscopy. The band edge exciton PL peak of Mn-doped 2D PEA2PbX4microcrystals was adjusted from 397 to 500 nm. The reduced Mn PL lifetime (1.37 to 0.21 ms) was monitored under ion exchange from Cl to Br to I. The degradation mechanism could be divided into two cases: (i) The halide ion migration in Mn-doped 2D perovskite under continuous illumination was revealed, suggesting that the migration of Cl ions was more accessible than that of Br and I. (ii) The PL redshift and lifetime reduction were observed after annealing at 420 K, which means that thermally induced aggregation of Mn ions resulted in the formation of Mn2+–Mn2+dimers. In addition, the experimental results indicated that the induced B-site phase separation at high temperature annealing made the mixed perovskite phase of Pb and Mn ultimately transform into pure PEA2PbBr4and PEA2MnBr4.

Aims: Dipeptidyl peptidase-4 inhibitors (DPP-4i) served as oral antidiabetic agents for treatment of type 2 diabetes mellitus (T2DM). Although an action on glucose homeostasis was identified, no well-rounded illustration had been established on the changes of tumor necrosis factor alpha (TNF-alpha) levels during DPP-4i treatment. This study aimed to explore the anti-inflammatory effect of DPP-4i on TNF-alpha in patients with T2DM. Methods: PubMed, Embase and Cochrane Library were systematically searched from inception to May 31, 2024. Randomized controlled trials exploring the impact of DPP-4i on TNF-alpha levels were identified. Risk of bias was assessed according to the Cochrane criteria. A fixed or random-effects model was selected to pool estimate on whether the heterogeneity was present. Subgroup analysis were performed to explore the potential factors that influenced heterogeneity. Related meta-analysis was conducted with the software of Revman 5.3 and STATA 12.0. Results: Eleven trials involving 884 participants with T2DM were included. Pooled estimates suggested that DPP-4i did not significantly modulate TNF-alpha levels (WMD, − 0.70, 95% CI − 1.94 to 0.53, P= 0.26) in T2DM. DPP-4i produced a significant effect on TNF-alpha (WMD, − 4.50 pg/mL, 95% CI − 4.68 to − 4.32, P< 0.00001) when compared to placebo, and a comparable effect was demonstrated on TNF-alpha (WMD, 0.10 pg/mL, 95% CI − 0.11 to 0.30, P= 0.35) in comparison with active agents. Estimate was stable according to the sensitivity test. Subgroup analysis revealed that heterogeneity might not correlate with baseline glycated hemoglobin (HbA1c), age or treatment duration. Conclusions: A significant effect of DPP-4i on TNF-alpha levels was present in T2DM when compared to placebo. Administration of DPP-4i produced no significant effect on TNF-alpha in comparison with active comparators. Further studies with large samples should be performed to illustrate the impact of DPP-4i on TNF-alpha levels in T2DM.

Using multifunctional organic ligands with multiple acidic groups (carboxylate and sulfonate groups) to synthesize metal–organic frameworks (MOFs) bearing effective H-bond networks is a promising strategy to obtain highly proton conductive materials. In this work, a highly stable two-dimensional MOF, [CuII5CuI2(μ3-OH)4(H2O)6(L)2(H2L)2]·3H2O (denoted as YCu161; H3L = 6-sulfonaphthalene-1,4-dicarboxylic acid) containing mixed-valence [CuII5CuI2(μ3-OH)4]8+subunits, was successfully prepared. It exhibited excellent stability and temperature- and humidity-dependent proton conduction properties. Its optimal proton conductivity reached 1.84 × 10–3S cm–1at 90 °C and 98% relative humidity. On the basis of a crystal structure analysis, water vapor adsorption test results, and activation energy calculations, we deduced the proton conduction pathway and mechanism. Apparently, uncoordinated sulfonic and carboxyl groups and a network of abundant H-bonds inside the framework were responsible for the efficient proton transfer. Therefore, the strategy of selecting suitable bifunctional ligands to construct two-dimensional Cu-cluster-based MOFs with excellent proton conductivity is feasible.

Stick–slip behavior between friction pairs causes severe vibration problems such as abrasion and noise pollution, leading to material loss and deterioration in human health. This phenomenon is extremely complex because the surfaces of friction pairs have various asperities with different sizes. Therefore, it is of importance to understand the scale effect of asperities on the stick–slip behavior. Here, we selected four kinds of zinc-coated steels with multiscale surface asperities as a presentative example to reveal what types of asperities play the key role in affecting the stick–slip behavior. It is discovered that the stick–slip behavior is dominated by the density of small-scale asperities rather than large-scale asperities. High-density small-scale asperity increases the potential energy between asperities of the friction pairs, which leads to stick–slip behavior. It is suggested that decreasing the density of small-scale asperity on the surface significantly suppresses the stick–slip behavior. The present study reveals the scale effect of surface asperities on the stick–slip behavior and thus could offer a pathway to tailoring the surface topography of a wide range of materials for suppressing the stick–slip behavior.

In this study, we prepared three highly stable coordination polymers under hydrothermal conditions, {[Zn2(μ3-DBd)2(H2O)2]·H2O}n(1), {[Cd(μ4-DBd) (H2O)]·3H2O}n(2), and {[Pb(μ4-DBd)]}n(3). Interestingly, the crystal-to-crystal transformation could occur between 1 and 3via means of cation exchange. 1and 2were two-dimensional structures and 3was a three-dimensional structure. The structure of 2contains a continuous hydrogen bond network, which can form an excellent hydrophilic channel. We explored the relationship between cation exchange-induced crystal-to-crystal transformation and water adsorption capacity, and proton conductivity. 1–3exhibited excellent stability and temperature- and humidity-dependent proton conduction properties. Among these, the water adsorption capacity of 2was 327.39 cm3·g–1, which was 8.14-fold and 39.23-fold than that of 1and 3, respectively. The proton conductivity of 2reached 1.67 × 10–4S·cm–1at 80 °C under 98% relative humidity, which was nearly 2 orders of magnitude higher than the proton conductivity of 1and 3. All the results indicated that the continuous hydrogen bond network inside the structure was responsible for the transfer of proton and increased the proton conductivity of coordination polymers.

This study examined the influence of worn surfaces on the stick–slip friction of galvanized automotive steel and revealed the intrinsic role of surface topography parameters in the stick–slip friction with wear. The results show that the surface deformation induced by wear significantly affects the stick–slip friction. The stick–slip friction can be suppressed by increasing the vertical area of the surface deformation because of reductions in the difference between the static and kinetic friction coefficients. The friction behavior changes from stick–slip friction to smooth sliding when the skewness exceeds a critical value, thus suggesting that this parameter can be used as an effective surface topography parameter to describe the stick–slip friction of galvanized automotive steel with worn surfaces. The findings can help improve the understanding of the mechanism of the stick–slip friction of materials with worn surfaces and provide an approach to suppress the noise and vibration caused by the stick–slip friction of galvanized automotive steel.

Abstract: A mechanical analysis is done to find the evolution of the interface profile between binary immiscible fluids induced by a three-dimensional orthogonal magnetic field gradient. In the experiments, the changes of the interface profile between four groups of binary immiscible fluids are investigated under the same horizontal magnetic field gradients. The binary immiscible fluids are made of benzene and other liquids, like CuSO4, Fecl3, FeSO4 or Cucl2 aqueous solutions. In addition, the interface profile between the benzene and CuSO4 aqueous solution is examined under different horizontal magnetic field gradients. The experimental results are consistent with the theoretical analysis. This study explains the enhanced Moses effect from a mechanics standpoint. Furthermore, a new method for susceptibility measurement is proposed based on this enhanced Moses effect.

The combined rotor of gas turbine is connected by a certain number of rod bolts. It works in the high temperature environment for a long time, and the rod bolts will creep and relax. Under the influence of elastic interaction, the loss of pretightening force of rod bolts at different positions is non-uniform, which will cause the connection of the combined rotor to be out of tune. In this paper, the creep relaxation non-uniformity model for a class F heavy duty gas turbine is established. On the basis of this, the performance degradation and structural strength change of combined rotor resulting from creep relaxation non-uniformity of rod bolts are studied. The results show that the ratio of preload mistuning increases with time and then converges, and there is a threshold inflection point in about seven thousand hours.