Simultaneous Enhancement of Thermal Insulation and Impact Resistance in Transparent Bulk Composites.

Transparent bulk glass is highly demanded in devices and components of daily life to transmit light and protect against external temperature and mechanical hazards. However, the application of glass is impeded by its poor functional performance, especially in terms of thermal isolation and impact resistance. Here, a glass composite integrating the nacre-inspired structure and shear stiffening gel (SSG) material is proposed. Benefiting from the combination of these two elements, this nacre-inspired SSG/glass composite (NSG) exhibits superior thermal insulation and impact resistance while maintaining transparency simultaneously. Specifically, the low thermal conductivity of the SSG combined with the anisotropic heat transfer capability of the nacre-inspired structure enhances the out-of-plane thermal insulation of NSG. The deformations over large volumes in nacre-inspired facesheets promote the deformation region of the SSG core, synergistic effect of tablet sliding mechanism in nacre-inspired structure and strain-rate enhancement in SSG material cause the superior impact resistance of overall panels in a wide range of impact velocities. NSG demonstrates outstanding properties such as transparency, light weight, impact resistance, and thermal insulation, which are major concerns for the application in engineering fields. In conclusion, this bioinspired SSG/glass composite opens new avenues to achieve comprehensive performance improvements for transparent structural materials.

Unexpected bending behavior of architected 2D lattice materials.

Architected two-dimensional (2D) lattice materials consisting of elastic beams are appealing because of their tunable sign of Poisson's ratio. A common belief is that such materials with positive and negative Poisson's ratios display anticlastic and synclastic curvatures, respectively, when bent in one direction. Here, we show theoretically and demonstrate experimentally that this is not true. For 2D lattices with star-shaped unit cells, we find a transition between anticlastic and synclastic bending curvatures controlled by the beam's cross-sectional aspect ratio even at a fixed Poisson's ratio. The mechanisms lay in the competitive interaction between axial torsion and out-of-plane bending of the beams and can be well captured by a Cosserat continuum model. Our result may provide unprecedented insights to the design of 2D lattice systems for shape-shifting applications.

Anomalous inapplicability of nacre-like architectures as impact-resistant templates in a wide range of impact velocities.

Nacre is generally regarded as tough body armor, but it was often smashed by predators with a certain striking speed. Nacre-like architectures have been demonstrated to dissipate abundant energy by tablets sliding at static or specific low-speed loads, but whether they're still impact-resistant templates in a wide range of impact velocities remains unclear. Here, we find an anomalous phenomenon that nacre-like structures show superior energy-dissipation ability only in a narrow range of low impact velocities, while they exhibit lower impact resistance than laminated structures when impact velocity exceeds a critical value. This is because the tablets sliding in nacre-like structure occurs earlier and wider at low impact velocities, while it becomes localized at excessive impact velocities. Such anomalous phenomenon remains under different structural sizes and boundary conditions. It further inspires us to propose a hybrid architecture design strategy that achieves optimal impact resistance in a wide range of impact velocities.

Clinical Efficacy of Antianlotinib Combined with Immune Checkpoint Inhibitors in the Treatment of Advanced Non-Small-Cell Lung Cancer and Its Effect on Serum VEGF, CEA, and SCC-Ag.

Purpose: This study is aimed at investigating the clinical safety and effectiveness of anlotinib combined with immune checkpoint inhibitors (ICIs) in the treatment of non-small-cell lung cancer (NSCLC). Methods: We selected 68 NSCLC patients treated at the Tumor Hospital Affiliated to Nantong University from October 2019 to January 2022. Patients receiving ICI monotherapy were included in the control group (n = 36), whereas patients receiving anlotinib combined with ICIs were enrolled in the study group (n = 32). The survival, adverse reactions (AEs), and short-term clinical effectiveness of the two groups were observed. The tumor markers (vascular endothelial growth factor (VEGF), carcino-embryonic antigen (CEA), and squamous cell carcinoma antigen (SCC-AG)) and T lymphocyte subsets (CD3+, CD4+, CD8+, and CD4+/CD8+) were determined before and after treatment. Results: Compared with the control group, the disease-control rate (DCR) and objective response rate (ORR) in the study group were substantially higher than that of the control group (62.50 vs. 36.11, 81.25 vs. 55.56; P < 0.05). The serum levels of VEGF, CEA, and SCC-AG in the two groups were considerably lower after two cycles of treatment (P < 0.05), and the serum levels of VEGF, CEA, and SCC-AG in the study group were significantly lower than those in the control group (P < 0.05). Following therapy, CD8+ in both groups decreased dramatically (P < 0.05), whereas CD3+, CD4+, and CD4+/CD8+ were significantly increased, but there was no statistical difference between the two groups (P > 0.05). The incidence of gastrointestinal, respiratory, cardiovascular, and immune-related adverse events did not significantly differ between the two groups (P > 0.05). The median progression-free survival (PFS) in the control and study groups for the first-line treatment patients was 7.2 and 9.8 months, respectively, whereas for the second-line treatment patients, it was 4.2 and 6.4 months, respectively. The mean PFS of study group was substantially longer than that of the control group regardless of the first- or second-line treatment. According to Cox analysis, the number of drug lines and TNM stage was independent risk variables impacting the prognosis of patients in this study. Conclusion: The combination of anlotinib with ICIs was more effective than either agent alone in the first- and second-line treatment of patients with advanced NSCLC. This treatment regimen did not interfere with immunological recovery or increase side effects.

Rate-Dependent Pattern Evolution in Peeling Adhesive Tape Driven by Cohesive Failure.

In the case of low-rate peeling, an adhesive can undergo a large tensile deformation through the viscous flow and form the fingering pattern at the peeling interface, resulting in homogeneous stripes on the peeled surface. In the case of high-rate peeling, no larger viscous deformation occurs, and no surface patterns will be generated. However, it is still unclear how the surface pattern evolves when an adhesive is peeled from a relatively low rate to a high rate. Here, by peeling an adhesive tape at 180° over a wide range of rates, we find that the adhesive tape can undergo a steady peeling. As the peeling rate increases, it is observed that the surface pattern in the peeled adhesive tape tends to evolve from the initial striped pattern to a crescent pattern, then to a spotted pattern. Even in the case of the stick-slip peeling at a small angle, the patterned region also presents the same evolutionary trend. By exploiting a high-speed camera to track the deformation process of the adhesive, it is found that this evolution is actually driven by the cohesive failure of the peeling adhesive. We describe the failure process, revealing the formation mechanism of the crescent pattern. We also discuss the effect of the peeling rate on the interface instability morphology by combining the finite element simulations, elucidating how the surface pattern evolves with the peeling rate.

The Effect of Subjective Exercise Experience on Exercise Behavior and Amount of Exercise in Children and Adolescents: The Mediating Effect of Exercise Commitment.

PURPOSE: To explore the influencing factors that restrict the exercise behavior of children and adolescents, investigate the effect of subjective exercise experience on exercise behavior, and reveal the mediating effect of exercise commitment between subjective exercise experience and exercise behavior so as to promote children and adolescents to maintain good health exercise habits and improve their physical and mental health. METHODS: The Subjective Exercise Experience Scale (SEES), Exercise Commitment Scale (ECC), and Physical Exercise Rating Scale (PARS-3) were used to conduct a questionnaire survey on 600 children and adolescents in Chongqing, China, and SPSS21.0 and AMOS21.0 statistical analysis software was used to carry out statistics and analyses on the questionnaires. RESULTS: (1) Among children and adolescents, boys' exercise commitment and exercise behavior were significantly higher than girls', and there was no significant gender difference in subjective exercise experience. The exercise behavior of children and adolescents aged 9-12 was significantly higher than that of children and adolescents aged 13-15, and there was no significant age difference in subjective exercise experience and exercise commitment. (2) There was a significant correlation between the subjective exercise experience, exercise commitment, and exercise behavior of children and adolescents, and subjective exercise experience could directly and positively predict exercise commitment (ß = 0.63) and exercise behavior (ß = 0.57)-exercise commitment could also directly and positively predict exercise behavior (ß = 0.52). (3) The exercise commitment of children and adolescents has a partial mediating effect between subjective exercise experience and exercise behavior (accounting for 37.50% of the total effect), and has a mediating effect between different exercise amounts, with the strongest mediating effect being on high exercise amount (32.10% of the total effect). CONCLUSIONS: The exercise behavior of children and adolescents was not only directly affected by subjective exercise experience, but also affected by the mediating effect of exercise commitment, and maintaining a good exercise experience and commitment was an effective way to effectively improve exercise behavior and amount of exercise in children and adolescents.

Scaling up ultrathin boat-graphane with the non-classical stiffness relation to macroscopic metamaterials.

Scaling up ultrathin nanosheets with unusual mechanical properties to macroscopic metamaterials is an intriguing topic considering the significant gap of their characteristic scales. In this regard, we investigate the relation between the in- and out-of-plane stiffness of monolayer boat-graphane in two principal axis directions by quantum mechanical calculations. A non-classical relation between the two types of stiffness is found, in opposition to the classical one for orthotropic thin plates. Analytical lattice dynamics models are proposed and suggest that the two kinds of stiffness stem from different covalent interaction sources, giving rise to the discrepancy. Guided by the geometry of boat-graphane and the model predictions, the non-classical relation successfully scales to macroscopic metamaterial plates, as justified by finite element simulations. The key structural parameters for successful scaling are also explored. The present work not only enriches our understanding of the nanomechanics of ultrathin nanosheets but also suggests a novel approach to construct mechanical metamaterials.

Recent progress on crack pattern formation in thin films.

Fascinating pattern formation by quasi-static crack growth in thin films has received increasing interest in both interdisciplinary science and engineering applications. The paper mainly reviews recent experimental and theoretical progress on the morphogenesis and propagation of various quasi-static crack patterns in thin films. Several key factors due to changes in loading types and substrate confinement for choosing crack paths toward different patterns are summarized. Moreover, the effect of crack propagation coupled to other competing or coexisting stress-relaxation processes in thin films, such as interface debonding/delamination and buckling instability, on the formation and transition of crack patterns is discussed. Discussions on the sources and changes in the driving force that determine crack pattern evolution may provide guidelines for the reliability and failure mechanism of thin film structures by cracking and for controllable fabrication of various crack patterns in thin films.

Atomistic simulations of mechanical response of a heterogeneous fcc/bcc nanolayered composite.

Molecular dynamics simulations are performed to study the mechanical properties and deformation mechanisms of a heterogeneous face-centered cubic/ body-centered cubic Cu/Ta nanolayered composite under uniaxial tension and compression. The results show that the stress-strain curves exhibit two main yield points in tension while only one yield point during compression, and the deformation primarily experiences three stages. The first stage is linearly elastic at small strains, followed by the nucleation and propagation of dislocations and stacking faults in the Cu layers, and eventually the Ta layers yield to plastic deformation. The yield of the specimen is mainly determined by the dislocation evolution in the hard phase (i.e. Ta layers), which leads to a sharp drop in the stress-strain curve. We show that the heterogeneous nanolayered composite exhibits a good deformation compatibility during compression but an obvious deformation incompatibility between Cu and Ta layers in tension. The temperature effect is also systematically investigated. It is revealed that the yield of the specimen at higher temperature depends only on the dislocation evolution in the thick Ta layers, and the yield strengths in tension and compression both decrease with the increasing temperature. In particular, our computations show that high temperature can significantly suppress the dislocation activities in the Cu layers during deformation, which results in a lower dislocation density of the Cu layers compared with that of the Ta layers and thus causing an incompatible fashion among the constituent layers.

A Prestressing Strategy Enabled Synergistic Energy-Dissipation in Impact-Resistant Nacre-Like Structures.

The application of prestresses is a valuable strategy for enhancing the overall mechanical performances of structural materials. Residual stresses, acting as prestresses, exist naturally in biological structural materials, such as the nacre with the 3D "brick-and-mortar" arrangement. Although regulation of the tablets sliding has recently been demonstrated to be vital to improve toughness in synthetic nacre-like structures, the effects of prestresses on the tablets-sliding mechanism in these nacre-like structures remain unclear. Here, by a combination of simulation, additive manufacturing, and drop tower testing the authors reveal that, at a critical prestress, synergistic effects between the prestress-enhanced tablets sliding and prestress-weakened structural integrality result in optimized impact resistance of nacre-like structures. Furthermore, the prestressing strategy is easily implemented to a designed nacre-inspired separator to enhance the impact resistance of lithium batteries. The findings demonstrate that the prestressing strategy combined with bioinspired architectures can be exploited for enhancing the impact resistance of engineering structural materials and energy storage devices.

Ordered ring-shaped cracks induced by indentation in metal films on soft elastic substrates.

Ordered crack patterns contain plentiful physical mechanisms and are useful for technological applications such as lithography, template, and biomimicry. Here we report on ordered multiple ring-shaped cracks induced by indentation in metal films on soft elastic polydimethylsiloxane (PDMS) substrates. It is shown that the indentation triggers the deformation of PDMS substrate and generates a radial tensile stress in the film, leading to the formation of ring-shaped cracks with a nearly uniform spacing. The morphological characteristics and evolution behaviors of the multiple ring-shaped cracks are revealed by optical microscopy, atomic force microscopy, and scanning electron microscopy. Their formation mechanisms are discussed by theoretical analysis based on the fracture mechanics. The report in this work can promote better understanding of the indentation-induced stress anisotropy and mode competition in rigid-film-soft-substrate systems and provide a facile strategy to control the crack patterns by simple mechanical loading.

Discontinuous fibrous Bouligand architecture enabling formidable fracture resistance with crack orientation insensitivity.

Bioinspired architectural design for composites with much higher fracture resistance than that of individual constituent remains a major challenge for engineers and scientists. Inspired by the survival war between the mantis shrimps and abalones, we design a discontinuous fibrous Bouligand (DFB) architecture, a combination of Bouligand and nacreous staggered structures. Systematic bending experiments for 3D-printed single-edge notched specimens with such architecture indicate that total energy dissipations are insensitive to initial crack orientations and show optimized values at critical pitch angles. Fracture mechanics analyses demonstrate that the hybrid toughening mechanisms of crack twisting and crack bridging mode arising from DFB architecture enable excellent fracture resistance with crack orientation insensitivity. The compromise in competition of energy dissipations between crack twisting and crack bridging is identified as the origin of maximum fracture energy at a critical pitch angle. We further illustrate that the optimized fracture energy can be achieved by tuning fracture energy of crack bridging, pitch angles, fiber lengths, and twist angles distribution in DFB composites.

Hierarchical crack patterns of metal films sputter deposited on soft elastic substrates.

Controlled cracks are useful in a wide range of applications, including stretchable electronics, microfluidics, sensors, templates, biomimics, and surface engineering. Here we report on the spontaneous formation of hierarchical crack patterns in metal (nickel) films sputter deposited on soft elastic polydimethylsiloxane (PDMS) substrates. The experiment shows that the nickel film generates a high tensile stress during deposition, which is relieved by the formation of disordered crack networks (called primary cracks). Due to the strong interfacial adhesion and soft substrate, the cracks can penetrate into the PDMS substrate deeply. The width and depth of the primary cracks both increase with increasing film thickness, whereas the crack spacing is insensitive to the film thickness. The film pieces dividing by the primary cracks can fracture further when they are triggered by an external disturbance due to the residual tensile stress, resulting in the formation of fine crack networks (called secondary cracks). The width and spacing of the secondary cracks show different behaviors in comparison to the primary cracks. The morphological characteristics, growth behaviors, and formation mechanisms of the primary and secondary cracking modes have been discussed in detail. The report in this work could provide better understanding of two distinct cracking modes with different sizes and morphologies.

Interaction between capped tetrahedral gold nanocrystals: dependence on effective softness.

Atomistic molecular dynamics simulations are performed to explore the interaction between two alkylthiol-capped tetrahedral gold nanocrystals (NCs) in a vacuum. The results highlight the influential role of the effective softness of the ligated NCs, i.e. the ratio of the ligand length to the core size. For sufficiently large softness, the relatively long ligand molecules round the shape of the NCs, causing their interaction to be nearly isotropic. For small effective softness, the relative shortness of the ligand molecules leads to a geometrically asymmetric morphology of the NCs, so that the interaction is orientation-dependent and is the strongest when the two NCs face each other with (111) facets. These findings are helpful for the understanding of interaction and structure formation in superlattices self-assembled from non-spherical ligand-capped NCs.

Growth of curved crystals: competition between topological defect nucleation and boundary branching.

Topological defect nucleation and boundary branching in crystal growth on a curved surface are two typical elastic instabilities driven by curvature induced stress, and have usually been discussed separately in the past. In this work they are simultaneously considered during crystal growth on a sphere. Phase diagrams with respect to sphere radius, size, edge energy and stiffness of the crystal for the equilibrium crystal morphologies are achieved by theoretical analysis and validated by Brownian dynamics simulations. The simulation results further demonstrate the detail of morphological evolution governed by these two different stress relaxation modes. Topological defect nucleation and boundary branching not only compete with each other but also coexist in a range of combinations of factors. Clarification of the interaction mechanism provides a better understanding of various curved crystal morphologies for their potential applications.

Tunable mosaic structures in van der Waals layered materials.

Intrinsic mosaic structures composed of distinctive stacking domains separated by domain walls (DWs) show the potential to regulate many outstanding properties of van der Waals layered materials. A comprehensive simulation at the atomic scale is performed to explore how the lattice/twist mismatch and the interlayer interaction influence the mosaic configuration from the incommensurate Moiré pattern to commensurate mosaic structures by adapting a complex amplitude version of the phase field crystal method. It is found that after an incommensurate-commensurate transition occurs, the topology of the mosaic structure indicated by different domain wall (DW) patterns can be drastically changed. An experimentally observed intriguing spiral domain wall (SDW) network is revealed as result of the emergent mixed dislocation driven by minimizing the elastic and interlayer energies in the presence of both lattice and twist mismatches. The transition process from a herringbone domain wall (HBDW) network to a SDW network is also simulated, elucidated by a dislocation reaction and in good agreement with the experimental observations.

Analysis of optimal crosslink density and platelet size insensitivity in graphene-based artificial nacres.

Exploration of graphene-based artificial nacres with excellent mechanical properties demonstrates the potential to surpass natural nacre. Recent experimental studies report that optimal crosslink density defined as concentration of the surface functional groups is usually observed in these artificial nacres towards superb mechanical performance. A hybrid model integrating a nonlinear shear-lag model and atomistic simulations reveals the emergence of an optimal crosslink density at which the maximum strength and toughness are achieved. The origin is due to the balance among the reduction of in-plane tensile properties of the graphene sheets, the enhancement of the shear strength of the interlayer and the reduction of interface plasticity. In addition, our results also reveal that the size insensitivity of the graphene sheet appears when the shear stress of the interlayer is highly localized, the increase of the crosslink density intensifies the nonuniformity of the shear stress and the optimal mechanical properties of the artificial nacre cannot be further enhanced by tuning the size of the graphene sheets. Three kinds of interface molecular interactions with their optimal crosslink densities are also proposed to simultaneously maximize the strength and toughness of graphene-based artificial nacres.

Tuning interfacial patterns of molecular bonds via surface morphology.

Many studies have demonstrated that the mechanical properties of the extracellular matrix can significantly influence the morphology, strength and lifetime of focal adhesions. However, how the morphology of the contact surface affects the pattern formation of the molecular bonds still remains largely unknown. Here, by simplifying the cell and extracellular matrix to two opposing elastic bodies and considering the lateral diffusion as well as the bonding/debonding of molecular bonds, we study the clustering behavior of receptor-ligand bonds between curved surfaces and the phase diagrams of cluster patterns. We reveal the important role of surface morphology and bond kinetics in regulating the patterns of bond clusters. We further investigate the segregation dynamics of the interfacial bonds under various loading speeds, and we show that the average interfacial stress is rate-dependent while the rupture stress is rate-independent. Finally, we demonstrate that programmable patterning of bond clusters can be achieved through the designed surface morphology.

Sphere-To-Tube Transition toward Nanotube Formation: A Universal Route by Inverse Plateau-Rayleigh Instability.

Nanotube formation in low-temperature solution has attracted intense interest since the 1990s. How to disclose the in-depth physicochemical nature of nanotubes and pursue new available chemical strategies is still highly desirable but remains a challenge. Here, we report that sphere-to-tube transition triggered by inverse Plateau-Rayleigh instability can be a chemical route for scalable production of nanotubes. As a proof of concept, formation of a phosphorus nitride (PN) nanotube and various hierarchical nanotube architectures by coalescence of the PN hollow spheres is achieved under systematic solvothermal reaction. The combination of theoretical analysis and dynamic simulation elucidates that the inverse Plateau-Rayleigh instability driven by the competition between curvature elasticity and surface energy is responsible for the PN nanotube formation observed in experiments. We anticipate that the sphere-to-tube transition provides a paradigm for nanotube synthesis for practical applications.

The shape of telephone cord blisters.

Formation of telephone cord blisters as a result of buckling delamination is widely observed in many compressed film-substrate systems. Here we report a universal morphological feature of such blisters characterized by their sequential sectional profiles exhibiting a butterfly shape using atomic force microscopy. Two kinds of buckle morphologies, light and heavy telephone cord blisters, are observed and differentiated by measurable geometrical parameters. Based on the Föppl-von Kármán plate theory, the observed three-dimensional features of the telephone cord blister are predicted by the proposed approximate analytical model and simulation. The latter further replicates growth and coalescence of the telephone cord into complex buckling delamination patterns observed in the experiment.