Mechanical Analysis Research Articles

Green innovation through trade: The impact of European Union emissions trading scheme on Chinese exporters

This paper investigates the international diffusion of green innovation through trade, focusing on the impact of the European Union Emissions Trading Scheme (EU ETS) on Chinese exporters. Using a difference-in-differences approach with firm-level data from 2000 to 2013, we find that the EU ETS significantly increased green patent applications among China-to-EU exporters. The likelihood of green patent applications increased by 0.2%, effectively doubling the pre-policy rate. Our mechanism analyses indicate that the increase is driven by the learning-by-exporting effect, rather than market size effects or the anticipation of regulatory and market condition changes. These results highlight the role of international trade in disseminating green technology and demonstrate how environmental regulations can foster innovation across global markets.

A Feasible Strategy for High-Performance Aqueous Zinc-Ion Batteries: Introducing Conducting Polymer.

Aqueous zinc ion batteries (AZIBs) offer great potential for large-scale energy storage because of their high safety, low cost and acceptable energy density. However, the cycle life of AZIBs is inevitably affected by parasitic reactions and dendritic growth caused by multiple factors such as electrode, electrolyte and separator, which pose significant obstacles to the practical application of AZIBs. To address these challenges, conducting polymer (CP) based materials have gained widespread attention in the realm of rechargeable batteries due to the adjustable band gap, controllable morphology, and excellent flexibility of CPs. In particular, CPs exhibit remarkable conductivity, low dimensionality, and doping characteristics, making them highly promising for integration into the AZIB system. In this review, the problems associated with the cathode, anode, electrolyte, and separator of AZIBs are discussed, and the application of CPs for their modification is summarized. The review provides a comprehensive analysis of the action mechanisms involved in the CP modification process and offers valuable insights for the design and development of CPs that can be effectively utilized in AZIBs. Additionally, the review presents a promising outlook of this research field, aiming to further advance the application of low-cost and high-performance CPs and their composites in AZIBs.

Mechanical, microstructural, durability, and energy analysis of fly ash geopolymer modified with autoclaved aerated concrete block waste

Mechanical, microstructural, durability, and energy analysis of fly ash geopolymer modified with autoclaved aerated concrete block waste

Long‐term Durability of Seawater Electrolysis for Hydrogen: From Catalysts to Systems

AbstractDirect electrochemical seawater splitting is a renewable, scalable, and potentially economic approach for green hydrogen production in environments where ultra‐pure water is not readily available. However, issues related to low durability caused by complex ions in seawater pose great challenges for its industrialization. In this review, a mechanistic analysis of durability issues of electrolytic seawater splitting is discussed. We critically analyze the development of seawater electrolysis and identify the durability challenges at both the anode and cathode. Particular emphasis is given to elucidating rational strategies for designing electrocatalysts/electrodes/interfaces with long lifetimes in realistic seawater including inducing passivating anion layers, preferential OH−adsorption, employing anti‐corrosion materials, fabricating protective layers, immobilizing Cl− on the surface of electrocatalysts, tailoring Cl− adsorption sites, inhibition of OH− binding to Mg2+ and Ca2+, inhibition of Mg and Ca hydroxide precipitation adherence, and co‐electrosynthesis of nano‐sized Mg hydroxides. Synthesis methods of electrocatalysts/electrodes and innovations in electrolyzer are also discussed. Furthermore, the prospects for developing seawater splitting technologies for clean hydrogen generation are summarized. We found that researchers have rethought the role of Cl− ions, as well as more attention to cathodic reaction and electrolyzers, which is conducive to accelerate the commercialization of seawater electrolysis.

Revealing the power of informal social support: Impact on rural migrants' entrepreneurial income

AbstractEntrepreneurship is a typical socially embedded activity and informal social support reflects the functional manifestation of unique social relationships among rural migrants. Given the limited attention in existing research, we employed data from the nationally representative China Labor‐force Dynamics Survey to investigate the impact and mechanism of informal social support on rural migrants' entrepreneurial income. We found that informal social support and its sub‐dimensions (instrumental and emotional support) significantly positively affect rural migrants' entrepreneurial income. A series of endogeneity and robustness tests substantiate this conclusion. Mechanism analysis suggests that these effects occur through the enhancement of entrepreneurial passion and mental health. Furthermore, using a cutting‐edge machine learning method (generalised random forests) to determine the basis for variable selection in heterogeneity testing, the results reveal that industry and age have the highest importance. Subsequent analysis shows that the above effects were more significant among rural migrant entrepreneurs in labour‐intensive industries and the younger generation. Finally, the theoretical and practical significance of this study has been discussed.

An oxidative depolymerized lignin treated by potassium ferrate and its use in preparation of epoxy resin

AbstractLignin, as an industrial by‐product, can be used as a phenolic substancen. In this study, enzymatic hydrolysis lignin (L) was treated with potassium ferrate and phenol respectively to obtain oxidized lignin (OL) and phenolated lignin (PL). Their phenolic hydroxyl content (PhOH) increased by 29.1% and 40.5%, respectively. Then four kinds of epoxy resins were prepared, namely lignin‐free epoxy resin (LFER), L epoxy resin (LER), PL epoxy resin (PLER), and OL epoxy resin (OLER). Gel permeation chromatography (GPC) and Fourier transform infrared analyses indicated that potassium ferrate oxidation could decline the molecular weight (Mw) and increase the PhOH of L. Mechanical properties test and dynamic mechanical analysis (DMA) results show that cured OLER (OLEN) has higher crosslinking density and better mechanical properties (shear strength increased by 14%, tensile strength increased by 15%) than cured LER (LEN). Thermogravimetric analysis results show that OLEN has better thermal stability than cured LFER (LFEN) and LEN. In addition, scanning electron microscopy images showed that the modified L had better compatibility. This study presents a novel approach for lignin oxidation.

Point-based Models: A Unified Approach for Geometric Constraint Analysis of Planar N-Bar Mechanisms with Rotary, Sliding, and Rolling Joints

Abstract Kinematic simulation of planar n-bar mechanisms has been an intense topic of study for several decades now. However, a large majority of efforts have focused on position analysis of such mechanisms with limited links and joint types. This paper presents a novel, unified approach to analysis of geometric constraints of planar n-bar mechanisms with revolute joint (R-joint), prismatic joint (P-joint), and rolling joint. This work is motivated by a need to create and program a system of constraint equations, which deal with different types of joints in a unified way. A key feature of this work is that the rolling joint constraints are represented by four-point models, which enables us to use the well-established undirected graph rigidity analysis algorithms. As a result, mechanisms with an arbitrary combination of revolute-, prismatic-joints, and wheel/gear/wheel-belt chains without any limitations on their actuation, can be analyzed and simulated efficiently for potential implementation in an interactive computer software and large-scale data generation.

Transitory sensitivity in automatic chemical kinetic mechanism analysis

AbstractDetailed chemical kinetic mechanisms are necessary for resolving many important chemical processes. As the chemistry of smaller molecules has become better grounded and quantum chemistry calculations have become cheaper, kineticists have become interested in constructing progressively larger kinetic mechanisms to model increasingly complex chemical processes. These large kinetic mechanisms prove incredibly difficult to refine and time‐consuming to interpret. Traditional sensitivity analysis on a large mechanism can range from inconvenient to practically impossible without special techniques to reduce the computational cost. We first present a new time‐local sensitivity analysis we term transitory sensitivity analysis. Transitory sensitivity analysis is demonstrated in an example to accurately identify traditionally sensitive reactions at an 18,000x speed up over traditional sensitivities. By fusing transitory sensitivity analysis with more traditional time‐local branching, pathway, and cluster analyses, we develop an algorithm for efficient automatic mechanism analysis. This automatic mechanism analysis at a time point is able to identify the reactions a target is most sensitive to using transitory sensitivity analysis and then propose hypotheses why the reaction might be sensitive using branching, pathway, and cluster analyses. We implement these algorithms within the reaction mechanism simulator (RMS) package, which enables us to report the automatic mechanism analysis results in highly readable text formats and in molecular flux diagrams.

Government green procurement and corporate ESG performance

This study utilizes data from China's A-share listed companies from 2009 to 2022 and manually collects government green procurement lists published on the Chinese government procurement website. By matching this data with listed companies, we employ a multi-period Difference-in-Differences (DID) model to examine the impact of a firm's inclusion in government green procurement lists on its Environmental, Social, and Governance (ESG) performance. We find that government green procurement significantly improves firms' ESG performance. In the mechanism analysis, we find that executive green perceptions and media and analyst attention amplify the positive impact of government green procurement on firms' ESG performance. Through the heterogeneity analysis, we find that government green procurement promotes ESG performance more significantly when the listed company is a state-owned enterprise, and this promotion is more obvious in central state-owned enterprises. In addition, we find that government green procurement enhances ESG performance more significantly when the company is located in a region with higher levels of market integration. Further research find that government green procurement effectively inhibit “greenwashing” behavior and reduce the probability of negative events. Our findings provide important micro-empirical evidence for understanding the effects of market-based policy instruments on corporate ESG performance and contribute positively to the practice of improving corporate governance capabilities.

D’Arcy Thompson and Synthetic Biology—Then and Now

AbstractThough often presented as a recent scientific endeavor, synthetic biology began in the 19th century and was a particularly active field in the years preceding the publication of D’Arcy Thompson’s On Growth and Form. Much synthetic biology of the era was devoted to the construction of nonliving chemical systems that would undergo morphogenesis or dynamic behaviors which had been observed in living organisms. The point was to show that “life-like” structure and behavior could be generated by physicochemical laws and required no vitalist element. D’Arcy Thompson’s careful analysis of physicochemical morphogenetic mechanisms as possible explanations of organic form links closely to this way of thinking. In the modern era, when we can genetically engineer cells to undergo specific behaviors, and program cells to undergo simple morphogenetic behaviors of the kind that Thompson and others felt might underly natural morphogenesis, it is possible to test whether they will in fact produce a predictable multicellular shape. This addresses essentially the same questions about the morphogenetic role of physicochemical forces, such as surface tension, but does so “the other way round”: physicochemical mechanisms are not being used as models for morphogenesis by natural cells but rather as a means to engineer cells to make designed forms.

Density functional theory investigation for noble gases adsorption on B3C2H5 structure

Quantum chemical calculations were performed to study the binding affinity of the B3C2H5 cluster with noble gases. The results indicate that noble gas atoms especially the heavier ones such as Xe and Kr can form stable complexes with this cluster. Detailed analysis of the interaction mechanism reveals that the noble gas atoms serve as donor fragments in the formation of Ng@B3C2H5, 2Ng@B3C2H5, and 3Ng@B3C2H5 donor–acceptor complexes.

Dynamic Analysis of Metamorphic Mechanisms with Impact Effects During Configuration Transformation

Metamorphic mechanisms have attracted considerable attention owing to their capability to switch their topology to adapt to different operational tasks. One feature of topological change is the re-contact of different bodies, which inevitably causes collisions affecting operation accuracy and service life. Consequently, in this study, a collision incidence matrix was introduced to describe the topology of a system involved in collisions, and a method for reducing the closed-loop system to an open-loop system was proposed. The complex movement of the metamorphic mechanism in a changing topology was classified into two different running stages of the source metamorphic mechanism. Based on the relative coordinate method, dynamic modeling of the source metamorphic mechanism considering the impact effects was conducted. Combining the classical collision theory and Newton–Euler equation, the generated impact impulse and the motion after collision were determined. Subsequently, a dynamic analytical method for the full configuration of metamorphic mechanisms was proposed to reflect the changes in the topological structure in the dynamic model. Finally, two typical metamorphic mechanisms used in packaging and spinning were considered as examples to verify the correctness and effectiveness of the proposed method, and their impact characteristics during configuration transformation were analyzed. The proposed analytical method of internal impact for a variable topology process provides effective theoretical guidance for the stability analysis of configuration transformation and structural design aimed at minimizing impacts.

Syn vs. Anti? What Controls Addition Stereochemistry in Chlorolactonization.

The stereochemistry of the uncatalyzed chlorolactonization of 4-phenylpent-4-enoic acid at room temperature was examined to probe the reaction's intrinsic diastereoselectivities as a function of chlorenium ion donor, solvent polarity, and reactant concentration ranges. Kinetic studies using Variable Time Normalization Analysis (VTNA) revealed differing reaction orders for the syn and anti alkene addition processes. Aided and illustrated by quantum chemical modeling, this detailed mechanistic analysis of the substrate's intrinsic chlorolactonization reactions points to concerted AdE3-type paths for both syn and anti additions. By illuminating the factors selecting for syn- vs anti-addition paths, the results provide key reference points for future studies of stereocontrol in halofunctionalization reactions.

Role of electrons and H* in electrocatalytic nitrate reduction to ammonium for CuNi alloy

Electrocatalytic reduction of nitrate (NO3-) to ammonium (NH4+) is an environment friendly approach for treating nitrogen-containing wastewater. Consequently, electrocatalysts capable of effectively and selectively reducing NO3- to NH4+ receives growing attention. However, Cu-based catalysts demonstrate limited efficiency and the drawback of generating toxic NO2- though it is prevalent in the field of electrocatalytic reduction of NO3- (NO3RR). In this work, a CuNi alloy was synthesized on a Co foil through electrodeposition (marked as CuNi@Co) and its electrocatalytic performance for NO3RR was evaluated. XRD, EDS mapping and XPS characterization indicate CuNi exists with alloy state. Electrocatalytic experiments demonstrate that CuNi@Co exhibits an exceptional FENH3 of 99.12% at -0.64 V (vs. RHE). Importantly, no detrimental NO2- generated during NO3RR process because the reduction rate from NO2- to NH4+ is faster than that from NO3- to NO2-. Mechanistic analysis suggests that Cu serves as a ‘reservoir’ to provide electrons to facilitate the reduction of NO3- to NO2- during NO3RR process and the synergistic effect of Ni and Cu promotes more active hydrogen (H*) to participate the reduction process of NO2- to NH4+ not H2 generation, ultimately improving FENH3. This work elucidates the role of electrons and H* in electrocatalytic nitrate reduction to ammonium for CuNi alloy, providing new insights into the reduction process of NO3RR for Cu-based materials.

Strong robust state of health estimation of lithium-ion batteries based on aging feature mechanism analysis and improved mixed kernel least squares support vector regression model

Strong robust state of health estimation of lithium-ion batteries based on aging feature mechanism analysis and improved mixed kernel least squares support vector regression model

Mechanism Analysis of Low-Frequency Oscillation Caused by VSG from the Perspective of Vector Motion

Virtual synchronous generators (VSGs) have attracted widespread attention due to their advantage in supporting voltage and frequency of power systems. However, relevant studies have shown that a VSG has similar low-frequency oscillation as synchronous generators, which is more likely to occur under strong grid conditions. In this paper, the linearized mathematical model of a VSG is established by using small-signal analysis; based on this, the physical process of low-frequency oscillation of a VSG is explained from the perspective of vector motion. Firstly, the amplitude and phase motion of the current vector of a VSG under small disturbance are analyzed, then the mechanism of negative damping caused by terminal voltage control is revealed, and the reason why a VSG is more prone to instability under strong grid conditions is explained. Based on these, the influence of control and grid strength on the low-frequency oscillation of a VSG is analyzed. Studies show that the amplitude motion of the output current is the main cause of negative damping, and the oscillation can be suppressed by optimizing the value of key parameters.

Impact of UV Light Exposure During Printing on Thermomechanical Properties of 3D-Printed Polyurethane-Based Orthodontic Aligners

Aim: Polyurethane-based aligners, created through photoinitiated free-radical polymerization, have been the subject of numerous studies focusing solely on their mechanical properties. In contrast, we investigate their thermomechanical properties, which are crucial for their efficacy. This paper aims to investigate the effects of different UV light exposure durations on the complex modulus of elasticity, tan delta, glass transition temperature, and the degree of conversion (DC). Methods: Aligners were printed using Tera Harz TC-85 and NextDent Ortho Flex resin with specific exposure times (2, 2.4, 3, 4, and 4.5 s for Tera Harz; 5, 6, 7, and 8 s for NextDent) and processed per manufacturer guidelines. The degree of conversion was analyzed using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, while Dynamic Mechanical Analysis (DMA) characterized the mechanical properties (complex modulus and tan delta) and the glass transition. Results: Tera Harz TC-85 showed a higher degree of conversion (90.29–94.54%), suggesting fewer residual monomers, which is potentially healthier for patients. However, its lower glass transition temperature (35.60–38.74 °C) might cause it to become rubbery in the mouth. NextDent Orto Flex, with a higher storage modulus (641.85–794.55 MPa) and Tg (49.36–50.98 °C), offers greater rigidity and stability at higher temperatures (greater than temperature in the oral cavity), ideal for orthodontic forces, though its lower degree of conversion raises health concerns. Conclusions: Tera Harz TC 85 generally achieves higher DC and more stable polymerization across different UV exposure times than NextDent Orto Flex. Optimal polymerization times significantly impact both the mechanical and thermal properties of these dental resins, with NextDent showing optimal properties at 7 s and Tera Harz benefiting from both very short and extended exposure times.

Chemical and Resistive Switching Properties of Elaeodendron buchananii Extract-Carboxymethyl Cellulose Composite: A Potential Active Layer for Biodegradable Memory Devices.

Biodegradable electronic devices play a crucial role in addressing the escalating issue of electronic waste accumulation, which poses significant environmental threats. In this study, we explore the utilization of a methanol-based extract of the Elaeodendron buchananii plant blended with a carboxymethyl cellulose biopolymer to produce a biodegradable and environmentally friendly functional material for a resistive switching memory system using silver and tungsten electrodes. Our analyses revealed that these two materials chemically interact to generate a perfect composite with near semiconducting optical bandgap (4.01 eV). The resultant device exhibits O-type memory behavior, with a low ON/OFF ratio, strong endurance (≥103 write/erase cycles), and satisfactory (≥103) data retention. Furthermore, through a comprehensive transport mechanism analysis, we observed the formation of traps in the composite that significantly improved conduction in the device. In addition, we established that altering the voltage amplitude modifies the concentration of traps, leading to voltage amplitude-driven multiple resistance states. Overall, our findings underscore the potential of functionalizing polymers that can be functionalized by incorporating plant extracts, resulting in biodegradable and nonvolatile memory devices with promising performance metrics.

Advanced Vitrimer with Spiropyran Beads: A Multi-Responsive, Shape Memory, Self-Healing, and Reprocessable Smart Material.

Thermosetting materials have limitations in terms of reshaping and recycling due to their irreversible bond structures, leading to significant plastic waste issues. Recently, epoxy vitrimers based on dynamic covalent bond exchange have been introduced as promising alternatives to traditional thermosets. Particularly, they demonstrate significant potential applications in the field of multi-responsive materials. In this research, a self-healable and mechano-responsive vitrimer (EB-V) is successfully prepared, incorporating epoxide spiropyran beads (ESP beads) derived from citric acid and epoxy derivatives. To enable self-reporting of cracks through color changes, ESP beads are covalently bonded to the vitrimer via an epoxy-carboxylic acid reaction. The photochromic properties of EB-V are demonstrated by color and fluorescence changes, and its tensile strength increased from 2.0 to 6.8MPa compared to the control sample. Dynamic mechanical analysis confirmed the covalent exchange reaction of the vitrimer, revealing its reconfigurable behavior and stress relaxation at elevated temperatures. Furthermore, EB-V exhibited exceptional properties, including self-healing and reprocessability. As a smart material, it holds great promise for a wide range of applications, such as sensors, actuators, 4D printing, and industrial safety diagnostics.

Green Financial Policy for Fostering Green Technological Innovation: The Role of Financing Constraints, Science Expenditure, and Heightened Industrial Structure

The environment has become an increasing concern due to the accelerated expansion of the world’s economy. Green finance is a crucial strategy for China to address challenges in fostering green innovation and achieving sustainable development. By employing the difference-in-differences (DID) method, this study assessed the influence of green financial policy (GFP) on green technological innovation (GTI) in the Yangtze River Economic Belt (YREB). The results indicate that GFP significantly improves GTI, especially in cities with a lower level of green finance development, cities with a medium level of GTI, and cities upstream of the Yangtze River. A mechanism analysis found that GFP promotes GTI in the YREB by alleviating financing constraints and increasing science expenditures. However, it fails to improve GTI through the heightened industrial structure. The findings provide empirical proof and policy direction for the reformation of green financing and the achievement of ecological transformation in the river basin economy in accordance with the ‘dual-carbon’ goal.