Mechanical Analysis Research Articles

Mechanism Analysis and Elimination of Multiple Pulse Phenomenon of Active Rectifier in Wireless Power Transfer Systems

Mechanism Analysis and Elimination of Multiple Pulse Phenomenon of Active Rectifier in Wireless Power Transfer Systems

Identification of a Transglutaminase from Bacillus amyloliquefaciens: Gene Mining, Protein Expression, Mechanism Analysis and Enzymatic Characterization

Transglutaminase (TGase) can catalyze the crosslinking within or between protein molecules, improving the structural and functional properties of proteins. It has been widely used in artificial meat, yogurt products, flour products and other foods. In this study, a high yield TGase strain was screened from fermented soybean, and it was identified as the Bacillus amyloliquefaciens XCT-09. Then, the transglutaminase (X9Tgl) from XCT-09 was expressed in Escherichia coli BL21(DE3), and the enzyme activity of purified X9Tgl reached 5.73 U/mg. Subsequently, the catalytic mechanism of X9Tgl was elucidated, and the X9Tgl contained the active center of E115, C116 and E187, as well as the substrate binding sites W149 and F69. Furthermore, this study characterized the enzymatic properties of X9Tgl, and the optimal catalytic temperature and pH were 60°C and 6, respectively. Moreover, X9Tgl exhibited stronger thermal stability and pH tolerance than STG, and it was not inhibited by the majority of metal ions. This study successfully identified a X9Tgl with high thermal stability, and pH tolerance, which provided a potential TGase resource for application in the food and medicine fields.

Fabrication of rGO/BiOI photocathode and its catalytic performance in the degradation of 4-Fluoroaniline

Organic fluorine compounds are acute carcinogenic and mutagenic to humans. Photoelectrocatalysis (PEC) treatment is an innovative technology in the field of the removal of fluorine compounds, and thus current research focused on improving stability and catalytic ability of photoanode. In this study , it has been synthesized a rGO/BiOI photocathode for the efficient degradation of 4-Fluoroaniline (4-FA). The physical characterization and photoelectrochemical properties of the photocathode was determined. The results indicate that the PEC treatment with the rGO/BiOI photocathode was more efficient compared with individual processes. During the optimization experiments, the PEC treatment achieved 99.58% and 72.12% of 4-FA degradation and defluorination within 1 hour. Cyclic stability experiments show that rGO/BiOI photocathode was efficient and stable, which reached 96.91% and 67.64% of 4-FA degradation and defluorination after five cycles. Mechanism analysis indicates that the PEC process was based on an electrochemical reaction and photo-induced processes. The degradation product of 4-FA was mainly 2,4-di-t-butylphenol, and trapping experiments indicates that h+ is the primary oxidizing species. Therefore, PEC treatment with rGO/BiOI photocathode is a competitive green approach to remove fluorine compounds pollutants and brings new insights into development of PEC treatment.

Development of a cellulose nanofiber composite film containing CuO/ZnO nanoparticles and its human norovirus inactivation properties in clams

Human norovirus (HuNoV) threatens human health worldwide, highlighting the critical need for antiviral materials. In this study, copper and zinc nanoparticles (NPs) as inorganic antiviral materials and a cellulose nanofiber (CNF) were selected to construct a hybrid inorganic-organic composite film (CuO/ZnO NPs-CNF) against MS2 and murine norovirus 1 (MNV-1) (surrogates for HuNoV) viruses. Selected NPs concentrations (50µM of CuO NPs and 5mM of ZnO NPs) showed non-toxicity (89.88% of cell viability) through the MTT assay. Upon the development and characterization of the CuO/ZnO NPs-CNF film, high compatibility between CuO/ZnO NPs and CNF was identified, along with consistent thickness, low moisture content, and water solubility. A synergistic antiviral effect was exhibited in vitro and on the film against MS2 and MNV-1 in the mentioned co-treated inorganic matrix within 1h. The antiviral stability of the film was also maintained at various temperatures (-18°C, 5°C, and 25°C) and humidities (20–30%, 50–60%, and 70–80%). When a synergistic antiviral effect was exhibited on the CuO/ZnO NPs-CNF film against both MS2 and MNV-1, mechanisms analysis by SDS-PAGE and RT-qPCR revealed that there were damages to both capsid protein and RdRP. The application of CuO/ZnO NPs-CNF film on clams resulted in a significant decrease in the survival rate of MS2 by up to 65.67% and MNV-1 by up to 78.62% when treated at low temperatures compared to the CNF film. Taken together, these results suggest that the CuO/ZnO NPs-CNF film could be used as potential anti-HuNoV agent in the food industry.

Acylhydrazone-functionalized starch for efficient removal of hazardous dyes, heavy metal ion, and sulfides from wastewater: Adsorption behavior and mechanism analysis

Herein, a novel acylhydrazone biosorbent (GSL) with abundant three-dimensional porous structure was successfully prepared by using low-cost starch as raw material for water pollution remediation applications. Various analytical techniques were applied to characterize the morphological structure and chemical composition. Interestingly, the adsorption efficiency of the adsorbent towards Malachite green (MG), Safranin O (SO), Cu2+, and sulfide in the static adsorption experiment was extremely high due to presence of ample functional groups. Additionally, the adsorption isotherm and kinetic experiments revealed that the adsorption processes were based on monolayer chemisorption. The maximum sorption amounts were 2237.4961 mg/g for SO, 2101.6610 mg/g for MG, 410.7019 mg/g for Cu2+, and 483.0194 mg/g for sulfides at 298.15 k. The thermodynamic analysis also demonstrated that all adsorption processes were spontaneous heat processes. The adsorption mechanism was analyzed by FTIR, SEM-EDAX and XPS. The adsorption of SO onto GSL reached 1025.8617 mg/g in continuous adsorption experiments, and the experimental data were fitted through the Thomas model and Yoon-Nelson model. Furthermore, the GSL showed good reusability and salt resistance. Importantly, starch-based acylhydrazone as the adsorbent for the simultaneous removal of hazardous dyes, heavy metal ions and sulfhides has not yet been seen reported.

Dominant modes of interannual variability in spring compound dry and hot events over Northern Asia and the possible mechanisms

In this study, spatial and temporal variations of spring compound dry and hot events (CDHEs) over northern Asia (NA) during 1950–2020 and the related possible mechanisms are investigated on the interannual timescale. The standardized compound event indicator (SCEI) is used to represent compound dry and hot conditions over NA, which is validated by the observed summer case of CDHEs over western Russia in 2010. The first empirical orthogonal function (EOF1) mode of the SCEI over NA presents a monopole pattern, while the EOF2 mode shows an east-west dipole pattern. Possible mechanism analysis indicates that the CDHEs tend to be modulated by local high-pressure anomalies, accompanied by reduced cloud cover and more solar radiation. The high-pressure anomalies can lead to warm temperature and water vapor divergence, which synergistically contributes to the occurrence of CDHEs. Further analysis shows that the EOF1 mode is jointly affected by the Scandinavian (SCAND) pattern and the Arctic Oscillation (AO); while the EOF2 mode is influenced by the Atlantic-Eurasian (AEA) teleconnection. Moreover, the North Atlantic tripolar pattern of sea surface temperature (SST) can influence the EOF1 mode through changing the AO. And the diagonal tripolar SST pattern over the North Atlantic affects the EOF2 mode via altering the AEA pattern. The influence of the SST patterns is further confirmed by numerical experiments using the Community Atmospheric Model version CAM-5.3.

Mechanism analysis for scaling effect on the impact behaviors of RC beam: From material properties to component response

Scaling effects on the resistance response of RC components have been found under impact, penetration, and blast. To investigate the mechanism and origins of the scaling effect on the impact response of RC beams, numerical models of geometrically similar beams were established on the ABAQUS platform by considering the strain rate effect. The influence of material properties such as elasticity, plasticity, and strain rate effect on the similarity of beam impact response was accessed and analyzed. Then, the scaling effects of impact characteristics such as time history, damage, effective mass, and span length of RC beams were discussed and compared from the local and global stages. The numerical findings revealed that material properties influence the scaling effect on the impact response and strain rate distribution. The inhomogeneity of strain rate distribution and the difference in dynamic strength caused by the non-uniform scaling for the strain rate effects (DIFs) contribute to the scaling effect. In addition, the two-stage analysis results indicated that the scaling effects exhibited in the local and global responses of RC beams are not entirely consistent. As the scale factor increases, for the large-sized beams, the normalized deformation profile shrinks, the equivalent mass factor decreases, the effective span length changes slower, and the moving velocity of the plastic hinge slows down. Several impact performance characteristics, such as strain rate distribution within the beam and the damage and deformation curve of the beam, will reflect localization as the scale factor increases. It is expected that the preliminary mechanism analysis of this study could provide a reference for analyzing the impact response of prototype beams.

The path of digital transformation driving enterprise growth: The moderating role of financing constraints

This study utilizes data from A-share listed companies of China between 2010 and 2021 to investigate the impact of digital transformation on corporate growth performance using a two-way fixed-effects model. We find that digital transformation has significantly promoted corporate growth performance, which remains robust across a series of tests. Mechanism analysis indicates that overall financing constraints and debt financing have significant moderating effects on the relationship between digital transformation and growth performance, whereas equity financing has similar effects only after PSM matching. Heterogeneity analysis shows that the promotion effect of digital transformation on growth performance is more pronounced in private enterprises, regions with superior business environments, and non-high-tech industries. Furthermore, both debt financing and equity financing were found to have a threshold effect on the growth performance promotion of enterprise digital transformation. Based on these, it is proposed that the configuration of enterprise capital scale and financing path should be considered when pursuing the positive effects of enterprise digital transformation.

Anchoring gadolinium oxide nanoparticles onto CuInZnS: Efficient photocatalytic tetracycline degradation and mechanism analysis

Photocatalysis technology is one of the potential methods to remit the growing issues of environmental pollution. It is of great significance to rationally design high performance antibiotic wastewater degradation catalysts in the whole pH range. In this experiment, Gd2O3 nanoparticles (GdO NPs) were successfully grown onto CuInZnS (CIZS) by a simple hydrothermal method. The introduction of GdO has obvious effects on the nanosheet thickness of CIZS, which reduces carrier transport distances and improves the active sites number of CIZS. What’s more, the SO4•- absorption and electron transfer ability are also greatly optimized. Under 300W Xe light, tetracycline can be efficient degraded more than 93% in the whole pH range, which presents absolute advantage compared to CIZS and GdO. Based on the combination of experimental characterization and density functional theory calculations, the proposed photocatalytic tetracycline degradation pathway and mechanism have been given. Moreover, the results of toxicity analysis proved that the CIZS-GdO catalyst could successfully reduce the toxicity of tetracycline wastewater. This work has reference value for the application of rare earth oxides in the field of photocatalysis at full pH range.

The Role of Speculation on Housing Price Disparities

This paper explores the impact of speculation on disparities in home purchase prices within neighborhoods. Using administrative data on residential real estate transactions in Singapore's private housing market, our analysis reveals that housing unit prices increase over time within a neighborhood in the presence of speculators. However, this pattern remains stable after the implementation of macroprudential policies aimed at deterring speculation. Our mechanism analysis indicates that while speculative sales contribute to the increase in the price of neighboring units over time, speculative purchases have negligible effects. These findings underscore the potential of macroprudential policies in mitigating speculation and promoting housing affordability.

Efficient degradation of tetracycline by Cobalt ferrite modified alkaline solution nanofibrous Ti3C2Tx MXene activated peroxymonosulfate system: mechanism analysis and pathway

Efficient degradation of tetracycline by Cobalt ferrite modified alkaline solution nanofibrous Ti3C2Tx MXene activated peroxymonosulfate system: mechanism analysis and pathway

Assessment of the advantages and limitations of an innovative silk fibroin scaffold for the reconstruction of the anterior cruciate ligament with preclinical in vitro and in vivo evaluations

The gold standard treatment in anterior cruciate ligament (ACL) reconstruction involves autologous tissue transplantation, but this can have complications. Artificial grafts are an alternative, but the best option is debated. This study aimed to assess the biocompatibility and integration of a silk fibroin textile prosthesis (SF-TP) with peri-implant bone tissue and the native ACL. Twenty-six sheep underwent ACL reconstruction with SF-TP or autologous femoral fascia lata (FFL). Sheep were divided into two groups (3 and 6 months) and retrieved joints processed for histological, morphometrical and mechanical analysis. In vitro, SF-TP showed no cytotoxicity and good cell interaction up to 14 days. Histology revealed fibro-vascular tissue around SF-TP, with a progressive attempt of ligamentous-like tissue formation at 6 months. However, SF-TP group had higher joint damage scores. Micro-CT showed tunnel enlargement in SF-TP group, while FFL group had a decrease. SF-TP reconstructions had lower stiffness and strength (44 % and 64 % decrease) than those of autologous FFL reconstruction and often failed by pull-out from the bone tunnel due to tunnel enlargement. These results indicate poor osteointegration and graft motion with SF-TP, leading to joint damage/bone resorption and reduced mechanical competence. These results do not support the use of SF-TP for ACL reconstruction.

Electro-coagulation pretreatment for improving nanofiltration membrane performance during reclamation of microplastic-contaminated secondary effluent: unexpectedly enhanced membrane fouling and mechanism analysis by MD-DFT simulation

Electro-coagulation pretreatment for improving nanofiltration membrane performance during reclamation of microplastic-contaminated secondary effluent: unexpectedly enhanced membrane fouling and mechanism analysis by MD-DFT simulation

Compliance analysis of transversely asymmetric flexure hinges for use in a piezoelectric Scott-Russell microgripper

Notch flexure hinges with longitudinal/transverse asymmetries can be widely found in compliant mechanisms to balance the performance trade-offs. However, the transverse asymmetry often leads to difficult analyses of kinetostatics and dynamics. In this paper, a miniaturized piezoelectric gripper featuring reversed Scott-Russell compliant amplifier with transversely asymmetric single-notched flexure hinges is designed for use in confined spaces. The compliance and vibration characteristics of the transversely asymmetric single-notched flexure hinges are quantitatively analyzed by a new transfer matrix method. The proposed theoretical methodology involves discretizing the transversely asymmetric flexure hinge into a series of constant beam segments with non-coaxial nodes, which enables a straightforward modeling process and hence simplifies the kinetostatic and dynamic analyses of compliant mechanisms comprised of complex flexure hinges. Comparative validations with respect to the finite element simulation and experiments confirm the advantages of easy operation and small-scale equation sets of the proposed modeling method. As to the designed piezoelectric microgripper with single-notched flexure hinges, the jaw displacement amplification ratio of 20 and resonance frequency of 1250 Hz has been experimentally tested with a small size of 38 mm×15 mm×7 mm.

Multiscale Analysis of the Function Mechanism of Aging Action on the Adhesion Properties between Asphalt and Aggregate

Multiscale Analysis of the Function Mechanism of Aging Action on the Adhesion Properties between Asphalt and Aggregate

Effect of cooling rates and heat treatment time on Si phase of AlSi10Mg alloy manufactured by selective laser melting: Microstructure evolution and strengthening mechanism

As a processing technique to change the organization and properties of materials, heat treatment was widely used to strengthen metallic materials. This study examines the impact of varying cooling rates and heat treatment durations on the mechanical properties and microstructure of AlSi10Mg alloys produced through Selective laser melting (SLM). The heat treatment process was Solution Heat Treatment (SHT, 525oC), and the heat treatment time includes 1h, 2h, and 3h. Cooling methods consist of Refrigerant Cooling (RC), Water Cooling (WC), Air Cooling (AC), Oil Cooling (OC), and Furnace Cooling (FC). As the cooling rate decreases and the heat treatment time increases, the size of the formed Si phase particles varies from small to large, and the distribution deviates from inhomogeneous to homogeneous. In addition, the number of precipitated particles increases and then decreases. To investigate the impact of cooling rates and heat treatment time on the mechanical properties of AlSi10Mg alloys, quasi-static tensile and compression tests were performed. On the other hand, the tensile strength of the heat-treatment samples decreases while the ductility increases, and the Vickers hardness of the samples also decreases with decreasing cooling rate and increasing heat treatment time. The results of the study showed that the cooling rate and heat treatment time of the material had a greater effect on its tensile properties than on its compressive properties. The samples treated at 525oC - 2h - AC exhibited the highest tensile and compressive properties. Finally, the analysis of the strengthening mechanism of AlSi10Mg alloys through the presence of Si phase particles of varying sizes was conducted using transmission electron microscopy.

Investigating the simulation test and acoustic emission characteristics of structural-control type rockbursts in deep underground environments

Deep underground projects are in a complex in-situ stress environment, and rock burst disasters induced by the hard and brittle failure of the rock mass are prone to occur around the tunnel openings. In this study, we aim to investigate the impacts of geological weak surfaces in rock masses on rockbursts and the spatiotemporal evolution of microcracks during the development of rockbursts. To achieve this objective, two sets of cubic specimens containing a circular through-hole were designed. One set of specimens had prefabricated unfilled cracks around the openings. Subsequently, the rockburst development process within the deep tunnel was replicated by subjecting both groups of specimens to identical gradient loading using a true triaxial test system. During the test, a micro camera was used to record the failure of the borehole wall in real-time, and an acoustic emission monitoring system was utilized to capture the stress waves released during structural damage. Finally, a multi-level synergistic analysis of the rockburst damage mechanism was carried out based on the macro-imaging data and micro-acoustic emission data. The results show that failure in high-stress environments within tunnels mainly includes microcrack initiation, particle ejection, crack propagation, local cracking, slabbing spalling, damage penetration, and rockburst damage. The time–frequency domain information of acoustic emission signals is highly perceptive and representative of the structural damage state of the specimens. The mutation characteristics observed in time-domain parameters, such as acoustic emission amplitude, event rate, ringing, and cumulative energy, correspond to drastic alterations in the internal structure of the rock. The distribution characteristics of frequency-domain parameters, such as acoustic emission peak frequency, dominant frequency energy, and frequency centroid, reflect different crack scales and damage modes. The diffusion of frequency centroid indicates that the damage and failure patterns within the rock are evolving towards a more complex direction. The energy magnitude of acoustic emissions represents the damage intensity during the development of rockburst. The root causes of induced structural-control type rockbursts in deep hard brittle rock masses are the combined effects of localized high-stress concentrations and large-scale discontinuous geological structures, such as natural joints, fissures, and structural planes. The naturally occurring large-scale through-type geological weak surfaces within the rock mass reduce the strength of the surrounding rock, alter the location of stress concentration, and change the initial damage characteristics. Moreover, they promote the evolution of rockbursts, thereby increasing their destructive intensity.

Analysis of tensile failure mechanism in intact, foliated, and cracked rocks using distinct element method: Influence of anisotropy

A thorough numerical analysis was conducted to understand the failure mechanisms and behaviour in intact rocks, foliated rocks and rocks with pre-existing cracks using the Brazilian tensile strength tests. The dominant anisotropy in rocks, especially foliated rocks like phyllites, slates and schists, as well as sedimentary rocks like sandstone, limestones and shale, leads to complex failure mechanism. The presence of cracks leads to anisotropy causing different mechanisms of failure and variation in tensile strengths of rock mass. Numerical simulations were conducted based on experimental studies of foliated phyllite and dolomitic limestone from the Tejam Group, Lesser Himalaya. The variations in failure behaviour and strength of foliated rocks were studied for samples at different foliation angle using the particle distinct element model. The simulation results show that with increase in foliation angle to the loading direction (from 0° to 90°), the peak tensile strength of rocks remains almost same for specimens with θ = 0° to 30° and then increases linearly till 90°. The influence of cracks as anisotropy was also studied by changing crack length (from 5 mm to 30 mm) and angle (from 0° to 90°). The development of failure patterns in rocks with pre-existing cracks leads to a better understanding of the failure modes and makes it possible to interpret failure behavior, pattern, and strength parameters. With increase in crack length, the tensile strength of rocks decreases. Overall, this study depicts the influence of anisotropy and microparameters on failure modes and behavior in Brazilian tensile strength tests on foliated and pre-cracked rocks.

From case study to general principle: An analysis of the development mechanism and policy optimization of mangrove carbon sinks

Mangroves, as a crucial coastal ecosystem, possess significant carbon sink functions and play a key role in mitigating global climate change. This paper, based on the Zhanjiang Mangrove Afforestation Project in Guangdong, explores the development mechanisms and economic and ecological benefits of mangrove carbon sink projects through the lens of collective action theory and system dynamics modeling. The study finds that the primary reason for the unsustainable progression of mangrove carbon sink projects is the lack of intrinsic motivation among local villagers to engage in collective action. By constructing a system dynamics model, this paper quantifies the long-term impacts of mangrove carbon sink projects on local socio-economic welfare and proposes policy optimization recommendations. These recommendations include expanding income sources for local villagers, establishing carbon trading and ecological compensation mechanisms, and involving international non-governmental organizations. The findings of this study not only provide guidance for mangrove carbon sink projects in China but also offer valuable insights for the promotion of similar projects globally.

Mixed superoleophilic/superoleophobic hard granular media for coalescence of oil-in-water-emulsion

To enhance the coalescence separation efficiency of oil/water emulsions, the coalescence mechanism of oil droplets between two media of opposite wettability was investigated. A coalescent-bed comprising a mix of superhydrophobic and superoleophilic quartz sand, along with superhydrophilic and underwater superoleophobic quartz sand, was constructed in a coalescer. Single-factor and response surface experiments were used to study the effects of oleophilic/oleophobic sand mixing ratio, apparent velocity, initial oil concentration, bed thickness, sand particle size on coalescence-separation performance, and to determine the optimal experimental conditions. Employing the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the agglomeration mechanism of oil droplets within the mixed particle bed was analyzed based on interfacial energy dynamics. Results indicate that the mixing ratio of the two sands significantly influences coalescence separation performance. An optimal oleophilic/oleophobic sand mixing ratio of 1:1 yielded a mass factor of 0.69 kPa−1, showcasing superior coalescence separation efficiency and an optimal balance of separation efficiency and pressure drop. Under the optimal conditions of apparent velocity of 2.7 m/h, initial oil concentration of 471.9 mg/L, bed thickness of 12.6 cm and mixed sand particle size of 0.5 mm, the oil/water separation efficiency reached 98.08 % ± 0.87 %, with effluent oil droplet size being 2.5 to 3 times larger than at the inlet. Analysis of the oil droplet coalescence mechanism revealed a synergistic effect between the two quartz sands, enhancing oil removal performance. The strong affinity of oil to the superhydrophobic and superoleophilic sand surface increases oil droplet wetting and coalescence efficiency, while the water attraction on the superhydrophilic and underwater superoleophobic sand surface forms a stable water film, improving the flux of the continuous water phase and reducing pressure drop across the bed. This study demonstrates that combining quartz sands of opposite wettability not only overcomes the limitations of single-wettability surfaces in coalescing oil removal but also achieves high efficiency and low energy consumption in oil removal.