Prediction of M3 B4 -type MBenes as Promising Catalysts for CO2 Capture and Reduction.

The rational design of novel catalysts with high activity and selectivity for carbon dioxide reduction reaction (CO2 RR) is highly desired. In this work, we have extensive investigations on the properties of two-dimensional transition metal borides (MBenes) to achieve efficient CO2 capture and reduction through first-principles calculations. The results show that all the investigated M3 B4 -type MBene exhibit remarkable CO2 capture and activation abilities, which proved to be derived from the lone pair of electrons on the MBene surface. Then, we emphasize that the investigated MBenes can further selectively reduce activated CO2 to CH4 . Moreover, a new linear scaling relationship of the adsorption energies of potential-determining intermediates (*OCH2 O and *HOCH2 O) versus ΔG(*OCHO) has been established, where the CO2 RR limiting potentials on MBenes are determined by the different fitting slopes of ΔG(*OCH2 O) and ΔG(*HOCHO), allowing significantly lower limiting potentials to be achieved compared to transition metals. Especially, two promising CO2 RR catalysts (Mo3 B4 and Cr3 B4 MBene) exist quite low limiting potentials of -0.48 V and -0.66 V, as well as competitive selectivity concerning hydrogen evolution reactions have been identified. Our research results make future advances in CO2 capture by MBenes easier and exploit the applications of Mo3 B4 and Cr3 B4 MBenes as novel CO2 RR catalysts.

Carbon doped hexagonal boron nitride as an efficient metal-free catalyst for NO capture and reduction.

The electrochemical NO reduction reaction (NORR) towards NH3 is considered a promising strategy to cope with both NO removal and NH3 production. Currently, the research on NORR electrocatalysts mainly focuses on metal-based catalysts, while metal-free catalysts are quite scarce. In this work, we have systematically investigated the properties of pristine and C/O doped h-BN for efficient NO capture and reduction. Our results reveal that the basal plane of pristine h-BN is inert to the adsorption of NO, while doping C or O can significantly enhance the NO capture abilities of h-BN. Then, we highlight that C-doped h-BN exhibits excellent NORR catalytic performance with a relatively low limiting potential of -0.28 V. Further analysis shows that the suitable adsorption strength of NO on the C-doped h-BN surface is the prime reason for its excellent NO reduction activity, which is shown to be due to appropriate electronic interactions between the active site and NO. Last but not least, the catalytic selectivity of h-BN towards the NORR is confirmed by inhibiting the competing hydrogen evolution reaction. Our findings not only provide deeper insight into the essential effect of element doping on the catalytic activities of h-BN, but also propose general design principles for high-performance metal-free NORR electrocatalysts.

Breaking linear scaling relations by strain engineering on MXene for boosting N2 electroreduction.

The development of N2 reduction reaction (NRR) electrocatalysts with excellent activity and selectivity is of great significance, but adsorption-energy linear scaling relations between reaction intermediates severely hamper the realization of this aspiration. Here, we propose an elegant strain engineering strategy to break the linear relations in NRR to promote catalytic activity and selectivity. Our results show that the N-N bond lengths of adsorbed N2 with side-on and end-on configurations exhibit opposite variations under strains, which is illuminated by establishing two different N2 activation mechanisms of "P-P" (Pull-Pull) and "E-E" (Electron-Electron). Then, we highlight that strain engineering can break the linear scaling relations in NRR, selectively optimizing the adsorption of key NH2NH2** and NH2* intermediates to realize a lower limiting potential (UL). Particularly, the catalytic activity-selectivity trade-off of NRR on MXene can be circumvented, resulting in a low UL of -0.25 V and high Faraday efficiency (FE), which is further elucidated to originate from the strain-modulated electronic structures. Last but not least, the catalytic sustainability of MXene under strain has been guaranteed. This work not only provides fundamental insights into the strain effect on catalysis but also pioneers a new avenue toward the rational design of superior NRR catalysts.

A review on guided-ultrasonic-wave-based structural health monitoring: From fundamental theory to machine learning techniques.

The development of structural health monitoring (SHM) techniques is of great importance to improve the structural efficiency and safety. With advantages of long propagation distances, high damage sensitivity, and economic feasibility, guided-ultrasonic-wave-based SHM is recognized as one of the most promising technologies for large-scale engineering structures. However, the propagation characteristics of guided ultrasonic waves in in-service engineering structures are highly complex, which results in difficulties in developing precise and efficient signal feature mining methods. The damage identification efficiency and reliability of existing guided ultrasonic wave methods cannot meet engineering requirements. With the development of machine learning (ML), numerous researchers have proposed improved ML methods that can be incorporated into guided ultrasonic wave diagnostic techniques for SHM of actual engineering structures. To highlight their contributions, this paper provides a state-of-the-art overview of the guided-wave-based SHM techniques enabled by ML methods. Accordingly, multiple stages required for ML-based guided ultrasonic wave techniques are discussed, including guided ultrasonic wave propagation modeling, guided ultrasonic wave data acquisition, wave signal pre-processing, guided wave data-based ML modeling, and physics-based ML modeling. By placing ML methods in the context of the guided-wave-based SHM for actual engineering structures, this paper also provides insights into future prospects and research strategies.

Investigation of thermo-acoustoelastic guided waves by semi-analytical finite element method.

Guided waves are sensitive to variations in propagation environments. Many recent studies have focused on the uniform thermal effect on Lamb waves. However, there is little research on the thermal effect in a more complex situation, such as a nonuniform thermal effect and wave propagation in an arbitrary cross-section. In this study, a thermo-acoustoelastic theory combined with the semi-analytical finite element (TAE-SAFE) method is proposed to investigate both uniform and nonuniform thermal effects on acoustoelastic guided wave propagation. In the TAE-SAFE method, effective thermo-acoustoelastic constants including third-order elastic constants are employed. Then, an acoustoelastic wave equation of the thermal effect is formulated by Hamilton's principle and computed by the semi-analytical finite element (SAFE) method. The phase velocity, group velocity, velocity thermal sensitivity, and displacement mode shape shift can be extracted by the proposed method. To validate this method, numerical results of Lamb waves in an aluminum plate subjected to a uniform thermal effect are compared with the results of a previous theoretical analysis. The results show computational veracity and validity. Two typical cases are investigated: (1) an isotropic aluminum plate under a linear temperature gradient condition; (2) a uniform temperature case in a rail track with a constant irregular cross-section. This study provides an effective numerical method to analyze thermo-acoustoelastic guided wave propagation.

Molecular dynamics simulation on the formation and development of interlayer dislocations in bilayer graphene.

Molecular dynamics simulations are used to study the formation and development of interlayer dislocations in bilayer graphene (BLG) subjected to uniaxial tension. Two different BLGs are employed for the simulation: armchair (AC-BLG) and zigzag (ZZ-BLG). The atomic-level strains are calculated and the parameter 'dislocation intensity' is introduced to identify the dislocations. The interlayer dislocation is found to start at the edge and propagate to the center. For AC-BLG, the dislocations arise successively with the increase of applied strain, and all dislocations have the same width. For ZZ-BLG, the first dislocation arises alone. After that, two dislocations with different widths appear together every time. The simulated dislocation widths are in good agreement with existing experimental results. Across every dislocation, there is a transition from AB stacking to AC stacking, or vice versa. When temperature is taken into account, the dislocation boundaries become indistinct and the formation of dislocations is postponed due to the existence of dispersive small slippages. Due to the disturbance of temperature, dislocations present reciprocating movement. These findings contribute to the understanding of interlayer dislocations in two-dimensional materials, and will enable the exploration of many more strain related fundamental science problems and application challenges.

Phosphocreatine Attenuates Isoproterenol-Induced Cardiac Fibrosis and Cardiomyocyte Apoptosis.

The present study was designed to further explore the role and the underlying molecular mechanism of phosphocreatine (PCr) for cardiac fibrosis in vivo. Isoproterenol (ISO) was used to induce cardiac fibrosis in rats. PCr administration ameliorated fibrosis by reducing collagen accumulation and fibrosis-related signals, including transforming growth factor beta 1 (TGF-ß1), alpha smooth muscle actin (α-SMA), collagen type I, and collagen type III. Mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB) signaling pathways, including p38, extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p65, were highly activated by ISO and blocked by PCr. Moreover, PCr decreased ISO-induced matrix metalloproteinase-9 (MMP-9) and increased the tissue inhibitor of metalloproteinase-1 (TIMP-1) expression. Furthermore, PCr suppressed cardiomyocyte apoptosis induced by ISO, as shown by downregulated expression of the proapoptotic caspase-3, Bax, and upregulated expression of the antiapoptotic Bcl-2. Taken together, PCr can be an effective agent for preventing cardiac fibrosis and cardiomyocyte apoptosis.

Lamb waves and electro-mechanical impedance based damage detection using a mobile PZT transducer set.

Lamb waves and electro-mechanical impedance (EMI) based methods are increasingly used in damage detection owing to their high sensitivity to small structural defects. Lamb wave based methods are effective in detecting damages in a large area and electro-impedance based methods are suitable for characterizing the identified damage. Based on these two methods, a novel combined damage detection method is presented in this research. To achieve this, first, a mobile transducer set is developed, which can be used for both the Lamb waves and EMI based methods. Then, a baseline-free damage detection strategy that combines the Lamb waves and EMI methods is presented. Finally, a laboratory-sized test piece is used to validate the effectiveness of the proposed approach. The results achieved with the application of the presented combined method for characterizing an L-shape crack in an aluminum plate show better location accuracy and detection efficiency than those obtained by applying only one method.