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Emerging flexible and wearable electronic products are placing a compelling demand on lightweight transparent energy storage devices. Owing to their distinguishing features of safety, high specific energy, cycling stability, and rapid charge/discharge advantages, Zn‐ion hybrid supercapacitors are a current topic of discussion. However, the trade‐off for optical transmittance and energy density remains a great challenge. Here, a high‐performance Zn‐ion hybrid supercapacitor based on the customizable ultrathin (5 µm), ultralight (0.45 mg cm−2), and ultra‐transparent (87.6%) Ni micromesh based cathode and Zn micromesh anode with the highest figure of merit (84 843) is proposed. The developed flexible transparent Zn‐ion hybrid supercapacitors reveal excellent cycle stability (no decline after 20 000 cycles), high areal energy density (31.69 µWh cm−2), and high power density (512 µW cm−2). In addition, the assembled solid flexible and transparent Zn‐ion hybrid supercapacitor with polyacrylamide gel electrolyte shows extraordinary mechanical properties even under extreme bending and twisting operation. Furthermore, the full device displays a high optical transmittance over 55.04% and can be conformally integrated with diverse devices as a flexible transparent power supply. The fabrication technology offers seamless compatibility with industrial manufacturing, making it an ideal model for the advancement of portable and wearable devices. [ABSTRACT FROM AUTHOR]

The residual stress of structural parts of welding machine tools at home and abroad was investigated. The welding bed,column and sliding saddle used in a vertical machining center were manufactured. And the tracking measurement of residual stress and deformation after welding and combined aging treatment were carried out. The results indicated that a large residual stress existed in the structural parts of welding machine tools which was over than 100 MPa. After welded,the maximum initial residual stress of the column,bed and sliding saddle reached 154. 9 MPa,274. 4 MPa and 300. 6 MPa,respectively. The maximum residual stress of the column guide rail,sliding saddle and bed respectively reached 1. 22 mm,2. 24 mm and 2. 88 mm,which approaching or exceeding yield strength of materials so that easily caused large deformation. Through the combined aging treatment of “post-welding-thermal aging-semi-finishing-vibration aging-finishing ”,the stress and deformation of the welding bed,sliding saddle and column are significantly reduced,the maximum residual stress respectively is reduced to 41. 9 MPa,39. 8 MPa and 18. 1 MPa,which all lower than 10%Rm,and the maximum straightness respectively is 36. 69 μm,23. 57μm and 19. 17 μm. After about six months,the deformation of the guide surface is 1 μm/1000 mm ～ 3 μm/1000 mm,which means good accuracy retention. The welding structure can be used for high precision CNC gold cutting machine tools and gear boxes.

The initial residual stress and deformation of welded body was measured respectively with blind-hole method and digital level. The test of residual stress after vibration aging,thermal aging and shot peening and the test of deformation after processing were done. The results show that the initial residual stress of welded body can reach up to 300. 6 MPa. The maximum deformation of the guide rails is 2882. 07 μm,which means obvious deformation. After complex aging process,the maximum residual stress of two welded bodys respectively is reduced to 43. 8 MPa and 12. 1 MPa,which both below 50 MPa. After processing,the maximum straightness of the guide rail respectively is 26. 7 μm and 25. 4 μm,which is significantly reduced.

The negative Poisson's ratio (NPR) effect usually endows materials with promising ductility and shear resistance, facilitating a wider range of applications. It has been generally acknowledged that alloys show strong advantages in manipulating material properties. Thus, a thought-provoking question arises: how does alloying affect the NPR? In this paper, based on first-principles calculations, we systematically study the NPR in two-dimensional (2D) GaN and AlN, and their alloy of AlxGa1−xN. It is intriguing to find that the NPR in AlxGa1−xN is significantly enhanced compared to the parent materials of GaN and AlN. The underlying mechanism mainly originates from a counter-intuitive increase of the bond angle. We further study the microscopic origin of the anomalies by electron orbital analysis as well as electron localization functions. It is revealed that the distribution and movement of electrons change with the applied strain, providing a fundamental view on the effect of strain on lattice parameters and the NPR. The physical origin as revealed in this study deepens the understanding of the NPR and shed light on the future design of modern nanoscale electromechanical devices with fantastic functions based on the auxetic nanomaterials and nanostructures. [ABSTRACT FROM AUTHOR]

High thermal conductivity is of great interest due to the novel applications in high-performance heat dissipation for microelectronic devices. Two-dimensional (2D) materials with graphene as a representative have attracted tremendous interest due to the excellent properties, where C23 is an emerging 2D allotrope of carbon with a large bandgap. In this paper, by solving the Boltzmann transport equation based on state-of-the-art first-principles calculations, the C23 is predicted to have an ultrahigh thermal conductivity of 2051.47 Wm−1K−1, which is on the same order of magnitude as graphene. Based on the comparative analysis among C23, graphene, and penta-graphene, it is shown that the unique spatial structure and the orbital hybridization of C23 lead to weak anharmonicity, which results in the large relaxation time of phonons and finally results in ultrahigh thermal conductivity. Our study is expected to promote the comprehensive understanding of thermal transport in C23 and shed light on future exploration of novel materials with high thermal conductivity. [ABSTRACT FROM AUTHOR]

With the miniaturization and integration of nanoelectronic devices, efficient heat removal becomes a key factor affecting their reliable operation. Two-dimensional (2D) materials, with high intrinsic thermal conductivity, good mechanical flexibility, and precisely controllable growth, are widely accepted as ideal candidates for thermal management materials. In this work, by solving the phonon Boltzmann transport equation (BTE) based on first-principles calculations, we investigated the thermal conductivity of novel 2D layered MSi2N4 (M = Mo, W). Our results point to a competitive thermal conductivity as large as 162 W m−1 K−1 of monolayer MoSi2N4, which is around two times larger than that of WSi2N4 and seven times larger than that of monolayer MoS2 despite their similar non-planar structures. It is revealed that the high thermal conductivity arises mainly from its large group velocity and low anharmonicity. Our result suggests that MoSi2N4 could be a potential candidate for 2D thermal management materials. [ABSTRACT FROM AUTHOR]

The event-by-event fluctuations of the mean transverse momentum (pt) in Au + Au collisions at –200 GeV and Pb + Pb collisions at are analyzed using a multiphase transport model (AMPT) with a dynamical quark coalescence mechanism (DQCM). The analysis shows that at 19.6 GeV there exists a splitting between the relative dynamical mean-pt fluctuation from the DQCM AMPT and from the original AMPT (i.e., AMPT with string melting) at freeze-out. Based on the hadron information obtained at different stages of nuclear collisions from the AMPT model, we show that this splitting first arises from the quark coalescence hadronization process, and then develops during the resonance decay process. The results are compared with measurements from STAR at the relativistic heavy-ion collider (RHIC) and ALICE at the large hadron collider (LHC). The comparison shows that the relative dynamical mean-pt fluctuation for non-peripheral collisions at 200 GeV and 2.76 TeV can be explained by these two coalescence scenarios. After introducing the DQCM into the AMPT model, the results become slightly larger and appeared to be closer to the experimental data for –62.4 GeV. Specially, the relative dynamical mean-pt fluctuation with centrality of 0%–5% can be well reproduced by the DQCM AMPT. [ABSTRACT FROM AUTHOR]

Heterostructure engineering of electrode materials, which is expected to accelerate the ion/electron transport rates driven by a built‐in internal electric field at the heterointerface, offers unprecedented promise in improving their cycling stability and rate performance. Herein, carbon nanotubes with Co9S8/ZnS heterostructures embedded in a N‐doped carbon framework (Co9S8/ZnS@NC) have been rationally designed via an in‐situ vapor chemical transformation strategy with the aid of thiophene, which not only acted as carbon source for the growth of carbon nanotubes but also as sulfur source for the sulfurization of metal Zn and Co. Density functional theory (DFT) calculation shows an about 3.24 eV electrostatic potential difference between ZnS and Co9S8, which results in a strong electrostatic field across the interface that makes electrons transfer from Co9S8 to the ZnS side. As expected, a stable cycling performance with reversible capacity of 411.2 mAh g−1 at 1000 mA g−1 after 300 cycles, excellent rate capability (324 mAh g−1 at 2000 A g−1) and a high percentage of pseudocapacitance contribution (87.5% at 2.2 mv/s) for lithium‐ion batteries (LIBs) are achieved. This work provides a possible strategy for designing multicomponent heterostructural materials for application in energy storage and conversion fields. [ABSTRACT FROM AUTHOR]