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We propose an asymptotic homogenization framework to simulate the fracture of heterogeneous materials. This framework upscales the phase field model for microscale fracture and yields anisotropic effective properties such as the degraded elasticity tensor and the fracture toughness. Furthermore, it quantitatively accounts for the toughening effect in a simple way. More specifically, when the critical energy release rate of a heterogeneous material is uniform, the framework reveals that toughening is essentially determined by the disparity in the moduli of toughness, the energy per unit volume absorbed by the constituents before cracking. • Asymptotic homogenization for phase field models for fracture. • Both the displacement field and the phase field are upscaled. • Tension-compression asymmetry in the underlying phase field model is incorporated. • Anisotropic fracture toughness tensor obtained with one single computation. • Under uniform fracture toughness, toughening depends on contrast in toughness moduli. [ABSTRACT FROM AUTHOR]

• Emerging g-DLP technique and shape memory polymers were employed to the dual information encryption. • Reconfigurable geometry and tunable optics provide the encryption and decryption behaviors under the stimulations of temperature and humidity. • The dual information encryption system is erasable, repeatable, and programmable. • The encrypted information system can be stored or decrypted permanently through the different post-processing methods. Dual information encryption such as geometry and transparency switching is highly desirable for preventing the leakage of confidential information and constructing a secure environment which has wide range of applications in privacy protection, anti-counterfeiting, and information security. However, it is still a challenge to develop a novel encrypted strategy and smart material to achieve credible protective capacity for stored information by a facile and programmed manner. Herein, integrating with arbitrary grayscale stereolithography, the hydrophilic ultraviolet (UV) curable shape memory polymers (HU-SMPs) with superior mechanical properties (the tensile strength of 29.39 MPa, elongation of 46.32 %, and the toughness of 1021.98 kJ.m−3) were prepared, which can be used for multifunctional information encryption. During the encrypted process, the HU-SMPs with the performances of high deformable and excellent shape memory behaviors can provide the preprogrammed morphological information and inevitable encryption, while the humidity-responsive of HU-SMPs capable of generating revisable transparency switching that can be encoded as the secondary information encryption. In this way, the dual encrypted information in the HU-SMPs is readable only after sequential shape recovery and fast hydration under heat-stimuli and humidity-stimuli. In addition, with the aid of digitally grayscale drawing, the secondary encrypted information is cyclically displayed and erasable due to the reversible hydration and dehydration process of HU-SMPs. Finally, the encrypted information is also can be permanently storage or decryption by the versatile post-processing methods of UV irradiation after and before decryption, respectively. In short, the design of HU-SMPs that compatible with grayscale digital light process (g-DLP)-based 3D printing, will motivates the future development of smart materials and provides a new insight into the information encrypt fields. [ABSTRACT FROM AUTHOR]

• For the first time, first-principles calculations are used to predict the lattice thermal conductivity of free-standing monolayer XS2 (X = mo and W) and monolayer XS2 supported on SiC (0001) and ZnO (0001) substrates. • The lattice thermal conductivity of monolayer XS2 supported on SiC (0001) and ZnO (0001) substrates show a significant decrease, and the decrease is even greater for the monolayer XS2 supported on ZnO (0001) substrates, reaching about 65–70 %. • The substrate drives softening of the acoustic branch, making the low-frequency phonon group velocity decrease and the three-phonon scattering enhance. • From the perspective of atomic bonding, the substrate breaks the symmetry of bonding of monolayer XS2, which leads to the increase of phonon anharmonicity and ultimately to a decrease in thermal conductivity of monolayer XS2. Thermoelectric materials have properties such as direct conversion of waste heat into electricity and environmental friendliness, which make them promising for renewable energy utilization, however, the lower conversion efficiency limits the large-scale application of thermoelectric materials. Monolayer transition metal dichalcogenides (TMDs) are candidates for thermoelectric materials due to their high power factor, but their higher thermal conductivity (TC) limits the further improvement of the figure of merit (ZT). Here, we employ first-principles calculations and solve the Boltzmann transport equation (BTE) to compare the lattice TC of free-standing monolayer XS 2 (X = Mo and W) and monolayer XS 2 supported on SiC (0001) and ZnO (0001) substrates. We find that the lattice TC of monolayer XS 2 supported on SiC (0001) and ZnO (0001) substrates are sharply reduced. Especially supported on the ZnO (0001) substrate, the lattice TC of XS 2 reduce by 65 %–70 %, which is expected to improve the thermoelectric properties of monolayer XS 2. In addition, we report the underlying cause of this significant reduction in TC. Firstly, the substrate drives softening of the acoustic branch, which leads to a decrease of phonon group velocity in the low-frequency and an enhancement of the three-phonon scattering. Then, the asymmetric bonding of XS 2 is induced by the substrates, which enhance phonon anharmonicity and reduce the phonon lifetime. Our results demonstrate that the lattice TC of monolayer XS 2 can be tuned by adjusting the substrate, which has certain reference values for the thermoelectric design of XS 2. SiC (0001) and ZnO (0001) substrates break the symmetry of the monolayer XS 2 (X = Mo and W) bonding, resulting in an increase in phonon anharmonicity, which reduces the contribution of the low-frequency acoustic branch of monolayer XS 2 to the thermal conductivity. [Display omitted] [ABSTRACT FROM AUTHOR]

Semi-parallel wire suspenders with spherical plain bearings have untwisting under axial force, and the collision in the untwist process bring adverse effects on the structure. To investigate the axial mechanical response of semi-parallel wire suspenders with spherical plain bearings, the equilibrium equations of suspender are deduced by assuming the distribution of steel wire after deformation, the forms of boundary conditions are distinguished according to the use of spherical plain bearing, and the linear equation expressed by equivalent stiffness coefficients is deduced. The Costello theory and finite element modeling are used to verify the proposed calculation method in this paper, and the influence of suspender parameters on the stiffness equivalent coefficient is analyzed. The results show that the proposed calculation method is suitable for multi-layer semi-parallel wire suspenders; the twist angle and the total number of layers of wires have the greatest effect on the stiffness equivalence factor; when the twisting angle is close to 0, the torsional stiffness of suspender is 0.010–0.21 of that of the steel rod with the same section; the axial tensile stiffness of the conventional suspender is basically the same as that of the steel rod with the same section, but the torsional stiffness is only 0.012–0.023 of the steel rod with the same section, and the tension-torsion coupling effect cannot be ignored. The research results provide a concise method to calculate the axial response of semi-parallel wire suspenders, which lays a foundation for the engineering treatment of the untwisting problem of semi-parallel wire suspender using spherical plain bearings. • The axial mechanical response of semi-parallel wire suspenders with spherical plain bearings is investigated. • The expression between axial resultant force, torque and overall strain of twisting structures is deduced and verified. • A concise method to calculate the axial response of semi-parallel wire suspenders is proposed. [ABSTRACT FROM AUTHOR]

In this study, the CW laser is used as a local heat source to simulate the extreme thermal environment generated by shock wave interference at discontinuities in spacecraft. The ablation behavior of the thermal protection material (C/SiC) is investigated under the combined impact of high-temperature airflow and the local extreme heat source. A novel multi-field coupling numerical computation software was presented to examine this strong coupling process of fluid-solid-thermal-ablation. The program was modified using the ALE + umeshmotion ablation calculation method in the ABAQUS software to mimic the process of the material's ablative boundary retreating under the action of the CW laser until the target was perforated. ANSYS Fluent software was used to do the numerical analysis of the high-speed airflow. The results of wind tunnel experiments and numerical simulations indicate that, compared to the effect of local heat sources in static air, irregular ablation pits are formed on the material surface under the action of local heat sources in high-temperature flow fields, resulting in higher ablation rates due to mechanical denudation effects. Analysis of the localization characteristics of the flow field near the ablation pit reveals that the shock wave generated downstream of the ablation pit leads to an increase in gas temperature, pressure, and density. When the ablation amount reaches a certain threshold, the gas in the ablation pit forms vortices, leading to an increase in local heat flow and pressure. [ABSTRACT FROM AUTHOR]

• Chlorella incorporated into hydrogels for continuous oxygen and bioelectric delivery. • Hydrogels offer mechanical support and create optimal microenvironment for Chlorella. • Hydrogels improve diabetic wound healing by enhancing proliferation and angiogenesis. Electrical stimulation and oxygen are vital for promoting cell proliferation, migration, and differentiation to repair damaged tissues in chronic wound healing in patients with diabetes. The effective oxygen production by Chlorella has garnered attention in the medical field, but the potential of extracellular electron production in skin repair has not been explored. Inspired by this, we developed CHPS hydrogels, a composite of polyacrylamide and sodium alginate, with Chlorella loaded in a semi-interpenetrating network. This network is formed by crosslinking acrylamide initiated by free radicals, with alginate chains dispersed within the network. When applied to wounds, CHPS hydrogels effectively protect damaged tissue, provide mechanical support to Chlorella against external forces, and create an optimal artificial microenvironment to promote the proliferation of Chlorella. Our study demonstrated that CHPS hydrogels exhibit remarkable fracture elongation and adhesion properties and continuously produce oxygen and bioelectrical currents through photosynthesis. Furthermore, the sustained release of dissolved oxygen and bioelectricity by CHPS hydrogels significantly enhances cell proliferation, migration, and angiogenesis, leading to improved wound healing in diabetic mice. These findings provide compelling evidence for further exploration of CHPS hydrogels as a cost-effective, simple, and accessible strategy for enhancing the clinical treatment of chronic wounds in diabetic patients. [ABSTRACT FROM AUTHOR]

In application scenarios such as astronautics, high-altitude aircraft, medical radiography, high-energy physics, and nuclear power plants, the irradiation resistance of electronic components is one of the basic requirements for their reliability. HfO 2 -based ferroelectric films have the advantages of high CMOS process compatibility, good miniaturizability, low operating voltage, and excellent irradiation resistance, which are the core materials for the new generation of irradiation resistance ferroelectric memories. In this paper, two kinds of metal-electrode ferroelectric capacitors, W/Hf 0.5 Zr 0.5 O 2 /W (WW) and Pt/Hf 0.5 Zr 0.5 O 2 /Pt (PP), have been prepared, and three gradient γ-irradiation experiments have been carried out on the two kinds of ferroelectric capacitors. The effect of metal electrodes on the irradiation resistance of Hf 0.5 Zr 0.5 O 2 ferroelectric thin films was carefully investigated by comparing and analyzing the statistical laws of polarization change and rectangularity change before and after irradiation of a large number of devices. The experimental results show that the WW devices have better irradiation resistance than PP devices, and we further explain the irradiation resistance mechanism by first-principle calculations and finite element analysis to verify the credibility of the experimental results. Finally, we conducted a comparative test of the fatigue and wake-up characteristics of the WW devices before and after irradiation, and the results show that the prepared W/Hf 0.5 Zr 0.5 O 2 /W devices can withstand very high total γ-dose radiation, reaching up to 13.86 Mrad(Si), and they are very suitable for the application of irradiation resistant electronics. [Display omitted] • The Hf 0.5 Zr 0.5 O 2 (HZO) thin films with outstanding ferroelectric properties were prepared. • The HZO ferroelectric thin films exhibited extremely high radiation tolerance (reaching up to 13.86 Mrad(Si)). • The effect of different metal electrodes on the irradiation resistance of HZO ferroelectric thin films was analyzed. [ABSTRACT FROM AUTHOR]