Mechanical Analysis Research Articles

Digital transformation of enterprises under the pressure of air pollution

ABSTRACT Although the effects of air pollution on economics have been reflected in recent research, very little literature has explored whether enterprises are actively adopting digital transformation under the pressure of air pollution. Considering the serious air pollution in China and the importance of digital transformation, this study uses the panel data of Chinese A-share listed companies and air quality data, from 2014 to 2020, to investigate the impact of air pollution pressure on digital transformation. The results show that air pollution pressure forces enterprises to engage in digital transformation. The conclusion still holds after endogeneity and robustness tests. Further, a mechanism analysis indicates that air pollution pressure affects digital transformation through green cognition, green innovation, and government subsidies. Meanwhile, regional informatization positively moderates the relationship between air pollution pressure and three mechanisms. Finally, a heterogeneity analysis shows that air pollution significantly affects digital transformation in eastern regions, state-owned, capital-intensive, and technology-intensive enterprises.

Photothermal Assisted Biomass Oxidation for Pairing Carbon Dioxide Electroreduction with Low Cell Potential.

Integrating anodic biomass valorization with carbon dioxide electroreduction (CO2RR) can produce value-added chemicals on both the cathode and anode; however, anodic oxidation still suffers from high overpotential. Herein, a photothermal-assisted method was developed to reduce the potential of 5-hydroxymethyl furfural (HMF) electrooxidation. Capitalizing on the copious oxygen vacancies, defective Co3O4 (D-Co3O4) exhibited a stronger photothermal effect, delivering a local temperature of 175.47 oC under near infrared light illumination. The photothermal assistance decreased the oxidation potential of HMF from 1.7 V over pristine Co3O4 to 1.37 V over D-Co3O4 to achieve a target current density of 30 mA cm-2, with 2,5-furandicarboxylic acid as the primary product. Mechanistic analysis disclosed that the photothermal effect did not change the HMF oxidation route but greatly enhanced the adsorption capacity of HMF. Meanwhile, faster electron transfer for direct HMF oxidation and the surface conversion to cobalt (oxy)hydroxide, which contributed to indirect HMF oxidation, was observed. Thus, rapid HMF conversion was realized, as evidenced by in situ surface-enhanced infrared spectroscopy. Upon coupling cathodic CO2RR with an atomically dispersed Ni-N/C catalyst, the Faradaic efficiencies of CO (cathode) and 2,5-furandicarboxylic acid (FDCA, anode) exceeded 90.0% under a low cell potential of 1.77 V.

Impact of the National Ecological Civilization Construction Demonstration Zone on corporate ESG: Evidence from China

This study examines the effect of implementation of the National Ecological Civilization Construction Demonstration Zone (NECCDZ) policy in China as a quasi-natural experiment on Chinese listed firms’ ESG performance. By utilizing a multi-period differences-in-differences model, the empirical results reveal that the NECCDZ policy boosted the ESG performance of China’s A-share listed companies in the pilot region by an average of 38%. However, the NECCDZ policy has differential effects on the three subdimensions of ESG. More specifically, the NECCDZ policy significantly improves the social responsibility performance and governance performance of the company, and has a lagged positive effect on the environmental performance. The mechanism analysis shows that the NECCDZ policy enhances corporate ESG practices by promoting enterprise green technology innovation, while media attention positively moderates the impact of the NECCDZ policy on corporate ESG practices. Further analysis shows that the NECCDZ policy also improves the enterprises’ financing environment through government subsidies and public investment. Overall, the empirical findings show the effectiveness of NECCDZ policy in enhancing ESG practices at the enterprise level and offer a new approach to improving corporate ESG finance in emerging markets such as China.

Designing the Second Target Station with a Coupled Neutronics-Mechanical Optimization Workflow

The Second Target Station (STS) at the Spallation Neutron Source of the U.S. Department of Energy’s Oak Ridge National Laboratory is being designed to become the world’s highest peak brightness source of cold neutrons. As the STS project evolves, neutronics and other engineering analyses will inform many design iterations. To facilitate this process, a fully automated optimization workflow was developed to convert a parameterized computer-aided-design model of the target into an unstructured mesh geometry model and then to run a neutronics calculation and (optionally) a mechanical analysis for each design iteration. This workflow enables efficient, high-fidelity modeling; simulation; and optimization of new designs, as has been demonstrated for the optimization of the STS neutron moderators. In this paper, we present the results of our first major effort to automate the design optimization process for a spallation target. In the first analysis, the goal is to find optimal dimensions of a monolithic tungsten target coupled with an optimal super-Gaussian proton beam profile to deliver maximum brightness of the resulting neutron beams while maintaining good mechanical properties of the target. In the second analysis, geometric and beam parameters are optimized for an alternative design with tungsten plates, which can reach superior mechanical performance without compromising the neutronics performance.

Syntaxin-6 delays prion protein fibril formation and prolongs presence of toxic aggregation intermediates.

Prions replicate via the autocatalytic conversion of cellular prion protein (PrPC) into fibrillar assemblies of misfolded PrP. While this process has been extensively studied in vivo and in vitro, non-physiological reaction conditions of fibril formation in vitro have precluded the identification and mechanistic analysis of cellular proteins, which may alter PrP self-assembly and prion replication. Here, we have developed a fibril formation assay for recombinant murine and human PrP (23-231) under near-native conditions (NAA) to study the effect of cellular proteins, which may be risk factors or potential therapeutic targets in prion disease. Genetic screening suggests that variants that increase syntaxin-6 expression in the brain (gene: STX6) are risk factors for sporadic Creutzfeldt-Jakob disease (CJD). Analysis of the protein in NAA revealed, counterintuitively, that syntaxin-6 is a potent inhibitor of PrP fibril formation. It significantly delayed the lag phase of fibril formation at highly sub-stoichiometric molar ratios. However, when assessing toxicity of different aggregation time points to primary neurons, syntaxin-6 prolonged the presence of neurotoxic PrP species. Electron microscopy and super-resolution fluorescence microscopy revealed that, instead of highly ordered fibrils, in the presence of syntaxin-6 PrP formed less-ordered aggregates containing syntaxin-6. These data strongly suggest that the protein can directly alter the initial phase of PrP self-assembly and, uniquely, can act as an 'anti-chaperone', which promotes toxic aggregation intermediates by inhibiting fibril formation.

Accelerated Proton Transfer in Asymmetric Active Units for Sustainable Acidic Oxygen Evolution Reaction.

The poor durability of Ru-based catalysts limits the practical application in proton exchange membrane water electrolysis (PEMWE). Here, we report that the asymmetric active units in Ru1-xMxO2 (M = Sb, In, and Sn) binary solid solution oxides are constructed by introducing acid-resistant p-block metal sites, breaking the activity and stability limitations of RuO2 in acidic oxygen evolution reaction (OER). Constructing highly asymmetric Ru-O-Sb units with a strong electron delocalization effect significantly shortens the spatial distance between Ru and Sb sites, improving the bonding strength of the overall structure. The unique two-electron redox couples at Sb sites in asymmetric active units trigger additional chemical steps at different OER stages, facilitating continuous proton transfer. The optimized Ru0.8Sb0.2O2 solid solution requires a superlow overpotential of 160 mV at 10 mA cm-2 and a record-breaking stability of 1100 h in an acidic electrolyte. Notably, the scale-prepared Ru0.8Sb0.2O2 achieves efficient PEMWE performance under industrial conditions. General mechanism analysis shows that the enhanced proton transport in the asymmetric Ru-O-M unit provides a new working pathway for acidic OER, breaking the scaling relationship without sacrificing stability.

Multi-objective optimization, shrinkage and fracture properties of unsaturated polyester resin modified concrete for bridge deck pavement based on system theory

For the purpose of fabricating unsaturated polyester modified concrete (UPMC) with excellent shrinkage and fracture properties for bridge deck pavement, the optimization design of mix proportion and enhancement mechanism analysis were implemented based on system theory. Firstly, for unsaturated polyester resin (UPR) subsystem, the viscosity, mechanical properties and droplet-size distribution were analyzed to determine the types and dosage of auxiliary additives after emulsification treatment; Next, for UPMC mortar slave-system, the optimization design was implemented through the combination of experimental analysis and hybrid multi-attribute ellipsoidal decision of grey-target (HMEDG) model; Subsequently, for UPMC main-system, the optimal proportion was determined utilizing orthogonal design test. Finally, the variation law and enhancement mechanism on fracture properties and shrinkage characteristics of UPMC was analyzed by combining macroscopic test, thermogravimetry (TG) and X-ray diffraction (XRD). The results demonstrated that 2.0 wt%BPO+1.0 wt%DMA and meta-benzene types UPR were utilized as auxiliary additives for UPMC based on the results of HMEDG models. The demulsified and cured WUP might supplement the interior moisture losses based on humidity compensation, and substantially constrain the evaporation loss inside the matrix, upgrading the hydration degree and facilitating the generation of hydration products. The introduction of 3 %-6 % waterborne-UPR (WUP) would improve 28d-fracture toughness within approximately 23.33 %-49.32 %, and reduce the shrinkage deformation by roughly 28–43 % through inducing the crack tip stress redistribution against the initiation and propagation of interior microcracks and enhancing the homogenization and densification.

Mechanism Analysis of the Reduction Process of the NiO-YSZ Anode of a Solid Oxide Fuel Cell by Hydrogen

Abstract Reduction of the nickel oxide-yttria stabilized zirconia (NiO-YSZ) anode is a significant step before the operation of a solid oxide fuel cell (SOFC). However, phenomena which occur during the reduction and their mechanism analyses are not summarized sufficiently. In this study, we investigated the influence of the hydrogen concentration, water vapor concentration of the reduction gas, Y2O3 content of the YSZ material of the anode, and temperature on the reduction process. The results showed that water vapor added to the hydrogen during reduction caused a temporary stasis period of the open circuit voltage. The length of the temporary stasis period was almost irrelevant to the water vapor concentration. During reduction, the length of the temporary stasis period of the open circuit voltage was negatively associated with hydrogen concentration and temperature, but positively associated with Y2O3 content of the YSZ material of the anode. After reduction, the SOFC showed better initial performance when the hydrogen concentration or the water vapor concentration during the reduction were higher. The classical shrinking core model can be used to explain these phenomena.

Impact and mechanism analysis of industrial robot imports on export performance of Chinese firms

Digital import trade is of great practical significance for enhancing the export performance of enterprises and preventing external shocks. This paper empirically examines the impact and mechanism of industrial robot imports on Chinese firms’ export performance based on Chinese microenterprise data from 2004 to 2014. The study shows that the application of imported robots can significantly improve firms’ export performance, and this conclusion still holds after a series of robustness tests. Heterogeneity analysis shows that imported robots have a more significant role in boosting the export performance of state-owned enterprises and enterprises in capital- and technology-intensive industries; at the same time, they have a significant effect on the export performance of enterprises in different modes of trade; and they have a significant role in boosting the export performance of enterprises in eastern China compared with those in central and western regions. Mechanism analysis shows that the enhancement of export performance of enterprises by imported robots is mainly realized by promoting enterprise productivity and human capital efficiency. The policy implication of this paper is that in the era of digital trade, Chinese enterprises should fully utilize the import of digital products to enhance their productivity and promote the high-quality development of foreign trade.

Environmental Protection Tax Reform in China: A Catalyst or a Barrier to Total Factor Productivity? An Analysis through a Quasi-Natural Experiment

China’s 2018 environmental protection tax (EPT) reform was introduced in response to increasing concerns about environmental degradation. It aimed to use fiscal policy to enhance environmental governance while fostering economic productivity. This study employs a difference-in-differences approach to analyze panel data from publicly listed companies between 2009 and 2019. It examines the reform’s influence on total factor productivity (TFP) in pollution-intensive industries, addressing both environmental and economic objectives. The results reveal that the tax reform significantly enhances TFP, acting as a robust catalyst for economic growth rather than a barrier. This effect is particularly strong in state-owned enterprises and those with less-severe financing constraints. Mechanism analysis indicates that the reform boosts TFP through the promotion of green innovations and alleviation of financing constraints. These findings provide empirical evidence at the micro-level of the reform’s efficacy in promoting sustainable business practices. The study offers insights for future environmental tax policies in China and underscores the necessity of aligning environmental and economic strategies to achieve sustainable development.

Impact on the scape of Farfugium japonicum var. japonicum (Asteraceae) under strong wind conditions based on morphological and mechanical analyses

Adaptation of Farfugium japonicum (L.) Kitam. var. japonicum (Asteraceae) to the strong wind environment of coastal areas has been shown to reduce lamina size and shorten petioles; however, their effects on other traits of this species remain unknown. Our morphological analyses showed that shortening of the scape of this species is correlated with shortening of the petiole in coastal areas. The results suggested that when the height of the scapes became higher than that of the petioles, the wind stress on the scapes became stronger and their growth was suppressed. Therefore, the populations in coastal areas with strong winds had significantly shorter scapes than inland populations, and the height of petioles and scapes in the coastal populations were correlated. Further mechanical analysis by three-point bending tests revealed that the scapes had higher strength than the petioles. This species is evergreen and can produce new leaves regardless of the season, even if it loses its leaves by strong winds; however, because scapes only develop above ground for a limited period of the year, the loss of the scapes by strong winds has a significant impact on reproduction in that year. Therefore, even though the scapes were stronger than the petiole, shortening the scapes plays an important role in reducing strong wind stress in coastal areas.

Analysis of the Molecular Mechanism of Energy Metabolism in the Sex Differentiation of Chickens Based on Transcriptome Sequencing

The determination of sex in mammals is established and controlled by various complex mechanisms. In contrast, sex control in poultry remains an unresolved issue. In this study, RNA-sequencing was conducted for male gonads and ovarian tissues in chicken embryos of up to 18.5 days to identify metabolic factors influencing male and female sex differentiation, as well as gonadal development. Our results reveal that PKM2, a critical glycolysis-related protein, plays a significant role in chicken sex differentiation via PPARG, a crucial hormone gene. We propose that our discoveries bolster the notion that glycolysis and oxidative phosphorylation function as antecedent contributors to sexual phenotypic development and preservation.

Research on the static and dynamic tensile damage mechanism of concrete based on fuzzy sets

The quantitative analysis of microscopic damage mechanisms in concrete and the formulation of damage evolution equations using mathematical theory and computerized tomography (CT) imaging are still emerging fields. The test data from CT scans have yet to be fully exploited. This study proposes a method for quantitatively characterizing mesoscale damage evolution in concrete. By segmenting CT images from static and dynamic tensile tests, we define metrics such as the aggregate rate, mortar rate, and porosity to examine the damage progression under both stress conditions. We then establish a damage evolution model based on porosity changes. Our findings reveal that crack growth in concrete is slower under static tension, with cracks navigating around aggregates towards weaker regions. Conversely, under dynamic loads, cracks propagate more rapidly and directly through aggregates, following paths of quicker energy dispersion. Static loading results in less aggregate damage than does dynamic loading, with a notable increase in porosity and a more varied change in the mortar rate. The damage to the finer components of concrete increases as the crack-adjacent region diminishes. Damage is generally more extensive under static loading than under dynamic loading. The proposed porosity-based damage evolution model effectively describes concrete damage under static tension, leveraging CT technology to enhance the universality of the research and offering a microscopic-level theoretical foundation for studying concrete mechanical properties.

Utilisation of dolomite dust with pure epoxy resin: Physical, mechanical and erosion wear analysis

AbstractUtilization of inorganic waste, if included in composite material, can be beneficial in reducing the accumulation of waste, which could help in resolving problems of disposal. beside from that, incorporating waste into composite materials also reduces the overall cost of the composites as a whole. The study examines the impact of dolomite content on the mechanical properties of the composites. Increasing the amount of dolomite in the composite significantly weakens its flexural strength, falling from 42.4 MPa at 0 % dolomite to 28.7 MPa at 15 % dolomite. Composite tensile strength also decreases by up to 25.8 % with rising dolomite dust concentration. Additionally, dolomite increases interlaminar shear strength (ILSS), with EDH15 composites showing the highest improvement. Dolomite dust in epoxy‐based composites increases the hardness value from 85 HRL to 95 HRL with an increase in dolomite dust content. The erosion test perform on air jet tester shows lowest wear rate was achieved under the following conditions: 10 % dolomite dust weight, 30° impingement angle, 10 m s−1 impact velocity, and 150 μm erodent size. Furthermore, scanning electron microscopy was used to examine the damaged, eroded surfaces for assumed wear mechanisms.

Short Glass Fiber Modifier Trisilanol–Isobutyl Polyhedral Silsesquioxane as Interfacial in Polypropylene Matrix: Effect of Flame Retardation and Mechanical Properties

In the present work, short glass fiber is superficially modified with different concentrations of polyhedral oligomeric silsesquioxanes (Trisilanol–Isobutyl, TSI-POSS) for processing as a filler in a polypropylene matrix (PP). It is observed that increasing the amount of TSI-POSS increases the fracture point and tensile strength; the opposite is the case for the strength impact property. The behaviors of both dynamic mechanical and thermal analyses are also observed. The flame behavior, i.e., the burning rate, decreases with increasing TSI-POSS in the polymers.

Building the fracture network model for the Okuaizu geothermal field based on microseismic data analysis

Understanding flow behavior in a geothermal reservoir is important for managing sustainable geothermal energy extraction. Fluid flow in geothermal reservoirs generally occurs in complex existing fracture systems in which the reservoirs are situated in highly fractured rocks. To simulate a discrete fracture model, the location and orientation of the fracture were computed using statistical processes and observational data. In many cases, estimating the location and orientation of fractures from 1D borehole logging data is challenging. In this study, we used microseismic data to build the fracture network systems and extract the detailed positions and dimensions of the fractures. We used the microseismic data recorded at the Okuaizu Geothermal Field, Fukushima Prefecture, Japan, from 2019 to 2021. First, we located the hypocenters, removing the effect of uncertainty in the velocity structure of the geothermal fluids. We relocated and clustered the seismic events based on waveform similarity. We analyzed each cluster to define the fracture orientation using principal component analysis (PCA) and focal mechanism (FM) analysis. We used the P polarity with the S/P ratio as a constraint for a better fault-plane solution. With PCA, we can extract the fracture dimension of each cluster. Our cluster analysis showed that the clusters were not always planar fractures, and we interpreted them as fracture zones. Based on the consistency between PCA and FM, each cluster/fracture zone was classified into three conceptual models to characterize the fracture network system in this field. This model showed variations in the orientation of small fractures within the fracture zone. We characterized the spatial variation in fracture distribution and orientations in the reservoir and demonstrated the fracture network system of this field. The fracture zone near the injection well has a N–S strike, and the dip is above 80°; however, the fracture zone in the northeastern part of the injection well has a NW–SE strike with a dip between 60° and 80°. The fracture network system estimated in this study is crucial for robust reservoir modeling because our model is more realistic, observation-orientated, and includes local anomalies of reservoir properties.Graphical

Mechanical performance study of PVA fiber-reinforced seawater and sea sand cement-based composite materials

Due to the swift progress in the construction sector, there is a global concern about the potential scarcity of river sand and freshwater resources. The development of new construction materials is considered an inevitable trend for industry growth. PVA fibers, known for their strong corrosion resistance, cost-effectiveness, and high toughness, have the potential to enhance the corrosion resistance and seismic performance of structures in marine environments. However, their mechanical properties and durability in the seawater and sea sand environment are not well understood. Therefore, the investigation of the impact of seawater and sea sand on the mechanical properties and durability of PVA fiber-reinforced cement composites is considered crucial. A mechanical performance analysis of PVA fiber-reinforced seawater and sea sand fiber cement composites was conducted in this study. PVA fiber volume fractions of 0%, 0.75%, and 1.5%, cement composite matrix strength grades of C30 and C50, and curing periods of 28 days, 90 days, and 180 days were examined, investigating their influence on the bending toughness of PVA fiber-reinforced seawater and sea sand cement composites. Specific conclusions include the addition of fibers increased the peak bending load, had a less corrosive effect in seawater, and improved the flexural toughness of the material. The most significant improvement was observed at 1.5% fiber content, where the load-deflection curve was fuller and the energy absorption capacity of the material increased by 33–109%, maintaining good bending toughness. Furthermore, higher fiber contents are required for high-strength cementitious composites to improve flexural toughness and durability. The formulation of calculation formulas for predicting bending strength and corresponding deflection, which fit well with the experimental results; and the development of a calculation model for the bending toughness index of PVA fiber-reinforced seawater and sea sand cement composites, providing an effective prediction of material bending toughness.

Mechanical and instability analysis of asphalt overlay during construction on cement concrete pavement with a large longitudinal slope

ABSTRACT There are insufficient stability problems in overlay construction on tourist highways in mountainous and island areas, especially the pavement with a large longitudinal slope. To elaborate on the instability characteristics of overlay, the construction stage of overlay is divided into loose state, paving stage and initial compaction stage. The moulding methods of specimens during the paving and initial compaction stages were determined. The evolution law of contact-slip characteristics and shear strength of overlay was analysed. The mechanical models of the construction stability of the composite pavements were constructed, instability characterisation methods were proposed and instability characteristics of asphalt overlay during construction were discussed. The results show that the paving state of overlay can be simulated by changing the rolling frequency and the compaction number. There is a risk of slip instability of loose overlay and the longitudinal gradient should be less than 12% to reduce this risk. The critical instability equivalent area ratio and critical slip area proposed can quantitatively describe the shape of the instability body and the instability critical condition. The longitudinal gradient significantly affects the interlaminar instability, but the internal instability mainly depends on the shear strength of asphalt overlay.

Erosion performance of direct-aged Al2O3-reinforced plasma-sprayed composite coatings at high-temperature conditions

The present investigation evaluates the influence of furnace heat-treatment (HT) on the microstructure, microhardness, fracture toughness and erosion resistance of three plasma sprayed composite coatings: a Inconel625–30 wt% micron-sized Al2O3 (In625-MHT) coating, a Inconel625–30 wt% nano-sized Al2O3 (In625-NHT) coating and a Inconel625–15 wt% micron-sized Al2O3 + 15 wt% nano-sized Al2O3 (In625-BHT/bimodal) coating. High temperature solid particle erosion tests were conducted at 900 °C temperature and with at two different impingement angles (90 and 30) in simulated environment using standard erosion-test rig. Coatings were subjected to detailed mechanical and microstructural analysis in order to better understand their erosion mechanism and structure–property correlation. By healing pores and cracks, the furnace HT increases the coatings’ erosion resistance in the order of In625-BHT, In625-NHT, and In625-MHTcoating. In addition, the mechanical properties of In625-BHT coating like porosity (1.0 ± 0.09%), micro-hardness (1299 ± 25Hv) and fracture toughness (5.9 MPa√m) are significantly improved after HT. The presence of grooves and lips on the surfaces of uncoated substrates provides clear evidence that the erosion mechanism involves the combined processes of micro-ploughing and micro-cutting indicating ductile erosion mode. However unimodal and bimodal composite coatings demonstrated a brittle erosion mode.

Metformin Regulates Cardiac Ferroptosis to Reduce Metabolic Syndrome-Induced Cardiac Dysfunction.

High-fat diet-induced metabolic syndrome (MetS) is closely associated with cardiac dysfunction. Recent research studies have indicated a potential association between MetS and ferroptosis. Furthermore, metformin can alleviate MetS-induced cardiac ferroptosis. Metformin is a classic biguanide anti-diabetic drug that has protective effects on cardiovascular diseases, which extend beyond its indirect glycemic control. This study aimed to assess whether MetS mediates cardiac ferroptosis, thereby causing oxidative stress and mitochondrial dysfunction. The results revealed that metformin can mitigate cardiac reactive oxygen species and mitochondrial damage, thereby preserving cardiac function. Mechanistic analysis revealed that metformin upregulates the expression of cardiac Nrf2. Moreover, Nrf2 downregulation compromises the cardio-protective effects of metformin. In summary, this study indicated that MetS promotes cardiac ferroptosis, and metformin plays a preventive and therapeutic role, partially through modulation of Nrf2 expression.