Main Damage Research Articles

Earthquake response and damage patterns assessment of two historical masonry churches with bell tower

The earthquake response of two historical masonry churches is investigated through a finite element macro-modelling approach and non-linear dynamic analyses. The main aim of the study is to evaluate the church walls effects on the seismic performance and damage patterns of slender bell towers, which are analyzed also in the isolated configuration to perform a comprehensive comparison with the confined counterpart. The results of the numerical simulations point out that both the churches, which present different sizes, structural features and dynamic properties, are highly vulnerable to low-to-moderate seismic actions and the bell tower is one of the most critical elements, suffering widespread damage due to also the interactions effects with the neighboring church walls. The presence of shorter adjacent structural elements significantly modifies the main structural dynamic characteristics, seismic response and damage patterns of the bell tower. For both the confined towers, the first cracks originate in the connection regions with the adjacent church walls: on the other hand, for both the isolated towers, the first cracks originate mainly at the base. An advance of damage onset is also detected in the case of confined towers with respect to isolated towers. At the end of the numerical analyses, for both the case studies, the confined configurations show more remarkable damage patterns and larger values of energy density dissipated by tensile damage than the isolated ones, presenting relevant cracks concentrations mostly near the connection regions with the church walls and in the middle-upper part of the bell tower. The results of this study emphasize the paramount importance of taking into account the interactions effects with the surrounding church walls for a proper damage and failure mechanisms assessment of bell towers within the church context: simplified analyses performed on isolated configurations without considering such interaction effects may lead to significant underestimations of damage for the bell tower inside the church.

The coupling effect of cavitation-erosion and corrosion for HVOF sprayed Cu-based medium-entropy alloy coating in 3.5 wt.% NaCl solution

Ship propellers suffered from serious coupling damage of cavitation-erosion (CE) and corrosion when operated with high-speed in the marine environment. To improve the CE-corrosion resistance of the Ni–Al bronze (NAB) propeller alloy, a novel Cu-based medium-entropy alloy coating (Cu55Al20Ni12Ti8Si5, at.%) was prepared by high-velocity oxygen-fuel spraying technology in this study. The characteristics and CE behavior of coating and NAB were comparatively investigated, then the CE damage mechanism was discussed by analyzing CE damage morphologies. The influence of CE on corrosion behavior and the coupling effect between CE and corrosion were further elucidated by electrochemical corrosion experiments. The results indicated that the as-sprayed coating mainly comprised of BCC solid solution phase and NiTi-rich precipitates, which possessed higher hardness (6.73 ± 1.23 GPa) and superior resilience (27.0%) than the NAB. The cumulative mass loss rate for the coating after 18 h CE in distilled water and 3.5 wt.% NaCl solution was only 38.7% and 80.6% that for the NAB, revealing the better anti-CE performance of the coating. The preferential CE of the BCC matrix around the NiTi-rich precipitates, fatigue fracture and lamellar spalling were summarized as the main CE damage mechanism for the coating in 3.5 wt.% NaCl solution. CE had a significant influence on corrosion behavior of coating and NAB, which resulted in corrosion performance degradation of both two materials. The CE-corrosion coupling effect led to the remarkable mass loss, and mechanical effect rather than corrosion effect was ascribed to be the dominated factor for the damage of coating and NAB.

HYDROGEN EMBRITTLEMENT OF PIPE STEELS

A review of literature data on the interaction of hydrogen with metallic materials is presented. The main damage processes such as high-temperature hydrogen corrosion and hydrogen embrittlement (HE) are reviewed. The most common mechanisms of HE are described. The well-known regularities and issues of the influence of the chemical composition, structure, hydrogen concentration, temperature and strain rate on the development of HE are generalized, and the results of our own studies of the effect of hydrogen on the mechanical properties of pipe steels are presented.

Effect of L‐T and S‐T orientations on fatigue crack growth in an aluminum 7050‐T7451 plate

AbstractThis study is focused on the anisotropic fatigue crack growth (FCG) behavior of an aluminum AA7050‐T7451 plate. L‐T and S‐T orientations were studied in M(T) samples with W = 50 mm, in mode I loading, with R‐ratio of +0.05. A numerical approach was used, assuming that crack tip plastic strain is the crack driving force. A purely kinematic elastic–plastic model was calibrated using experimental data from low cycle fatigue tests of smooth specimens in L and S orientations. The predicted FCG rates agree well with experimental trends in the Paris' regime, suggesting that cyclic plastic deformation is the main damage mechanism. The numerical model was used to estimate the stress ratio effect for both orientations, which was found to be linked with crack closure variations. However, the closure free predicted trends for both microstructural orientations at R = 0.05 are not overlapped, suggesting an effect of microstructure not linked to crack closure.

On the automated characterisation of inclusion-induced damage in 16MnCrS5 case-hardening steel

Manganese sulphide inclusions are commonly found in steels and known to facilitate the formation of deformation-induced damage sites in the form of voids during cold forming. These damage sites either exist as cracks, splitting the inclusion in two parts, or as delamination, separating the inclusion from the surrounding steel matrix. Both negatively influence the longevity of components, especially under cyclic loading. The analysis of damage is inherently scale-bridging, ranging from deteriorated global mechanical properties of the finished part, over the damage behaviour of individual inclusions, to the local description of individual voids. In this work, we set out to devise an analysis approach gathering information on all these scales. To this end, we conducted in-situ tensile tests while acquiring high resolution SEM panoramic images and analysed them with two neural networks, trained for this work, to detect damage sites with respect to the inclusions at which they nucleated. We find that the main damage mechanism during tensile deformation parallel to the length of inclusions is cracking and that damage evolution is equally influenced by void nucleation and void growth in the observed range of deformation. By focussing on the damaging behaviour of different inclusions, we show that the position of inclusions in the microstructure influences the resulting damage evolution and that the vicinity of pearlite bands leads to decreased damage formation.

Risk-based inspection (RBI) of a gas pressure reduction station

One of the principles of corrosion management is proper inspection methodology, and in particular the risk-based inspection (RBI). Occasionally a large percentage of the total risk of a unit is concentrated in a small part of the equipment, which can be reduced by using risk management techniques. In this study, a semi-quantitative risk-based inspection method has been performed in a gas station with for its components (pipelines, filters, etc.), to identify the existing damage mechanisms and also to rank its equipment in terms of inspection intervals. In this regard, RBI was performed for the gas station which consisted of phases (Phase A & Phase B) with Class 300 and Class 600 equipment. According to documented conditions and reviewed records the main damage mechanism for the investigated components in the gas station was identified as wall thinning due to erosion corrosion and external corrosion. In terms of inspection, results showed that most of the equipment studied had medium risk level and a few had medium to high level of risk. In this regard, the corrosion rates of Class 300 and Class 600 equipment were also studied and compared, and it was indicated that the corrosion rates were higher at locations for Class 300 equipment where more pressure drop had occurred. Overall, based on the obtained corrosion rates and obtained risk matrixes, it was concluded that wall thinning (erosion-corrosion) was the determining risk factor for equipment inspected in the gas pressure reduction station.

К вопросу о допустимости дефектов в нижнем поясе подкрановых балок

Crane beams are among the most damaged structures in the buildings with heavy, and very heavy-duty overhead cranes. Their destruction can lead to the death of people working in the workshop, and to significant material losses. The durability of crane structures is determined by the intensity of work of the overhead cranes. The main defects and damages of metal crane beams are regulated by the standard STO-22-05—04, according to which all the cracks in the crane beams are divided into groups according to the risk of destruction. It is believed that the presence of cracks in the lower (stretched) chord of crane beams is unacceptable. Modern methods of non-destructive testing allow to detect defects with a minimum size from 2 mm (ultrasound) to 1 µm (capillary method). These cracks may be due to the inhomogeneity of the chemical composition of the alloy, or be of a structural nature, manifesting itself, in contrast to fatigue cracks that grow in the most loaded areas of the structure, in any part of the lower chord of the beam. If any crack is found in the lower chord of the crane beams, it is required to stop the operation of the crane and carry out a major overhaul of the crane runways. However, following these formal rules is not always economically and logically justified. The paper considers an example of rationing by the criterion of non-straining through cracks in the lower stretched chord (cracks of the first group). Based on the criteria of linear fracture mechanics, coefficients are proposed for all steels from which the crane beams are made, allowing for their technical inspection to give an express assessment of the admissibility of the detected through cracks. It is also shown that it is necessary to normalize the permissibility of the parameters of semi-elliptical cracks in the stretched zone (in the lower shelf of the I-beam crane beam), since these cracks can eventually develop into through defects.

Effect of dissolved metabolites of the dinoflagellate Gymnodinium catenatum (Graham, 1943) on the white shrimp Litopenaeus vannamei (Boone, 1931): A histological study

Harmful algae blooms (HABs) are a conspicuous phenomenon that affect the coastal zone worldwide. Aquaculture industry zones are not excluded from being affected by HAB that cause organism mortality and jeopardize their innocuity due to the contamination by phytotoxins with the concomitant economic losses. Direct ingestion of metabolites from HAB species or organisms contaminated with phycotoxins together with dermal absorption of dissolved metabolites (DM), including toxins, are the two main routes of poisoning. From these poisoning routes, the effect of DM, particularly paralytic shellfish toxins (PST), has been relatively understudied. This intoxication route can be conspicuous and could be involved in many significant mortalities of cultivated marine organisms. In this study, white shrimp juveniles (2.1 g wet weight) of Litopenaeus vannamei were exposed to extracts of 104, 105 and 106 cells/L of the dinoflagellate Gymnodinium catenatum, a PST producer. The experiment ended after 17 h of exposure when shrimps exposed to 106 cells/L extract started to die and the rest of the shrimps, from this and other treatments, did not respond to gentle physical stimulus and their swimming activity was low and erratic. Toxin concentrations were determined using high performance liquid chromatography while qualitative and quantitative histological damages were assessed on the tissues. In general, most toxins were accumulated in the hepatopancreas where more than 90% were found. Other tissues such as intestine, muscle, and gills contained less than 10% of toxins. Compared to the control, the main significative tissue damages were, loss of up to 80% of the nerve cord, 40% of the muscle coverage area, and reduction of the gill lamella width. Also, atrophy in hepatopancreas was observed, manifested by a decrease in the height of B cells, lumen degeneration and thinning of tubules. Some damages were more evident when shrimps were exposed to higher concentrated extracts of G. catenatum, however, not all damages were progressive and proportional to the extract concentration. These data confirm that PST dissolved enter the shrimp, possibly via the gills, and suggest that dissolved metabolites, including PST, may cause tissue damage. Other dissolved metabolites produced by G. catenatum, alone or in synergy, may also be involved. These results also pointed out the importance of dissolved molecules produced for this dinoflagellate and the potential effect on cultured shrimp.

КОРРЕКТИРОВАНИЕ ПЕРИОДИЧНОСТИ ОПЕРАЦИЙ ТЕХНИЧЕСКОГО СЕРВИСА МОБИЛЬНЫХ МАШИН С УЧЕТОМ ЖЕСТКОСТИ КЛИМАТА

Based on the analysis of the main operational factors, among which, for specific areas of equipment supply, one of the main ones is the climatic factor, as well as the main damaging degradation processes during the operation of machines, an effective mechanism for planning the frequency of maintenance operations is proposed, which helps to ensure a high level of technical readiness of machines. The operability potential was analyzed, its active, reserve and passive parts were considered, which made it possible to present a model for changing and restoring the operability potential of a mobile machine. Mathematical dependences are given for certain models of machines of the same functional purpose, as well as characterizing processes of reducing the potential of their performance in a certain external environment, their transformation is noted when changing natural and climatic operating conditions. The construction of a priori diagram of the ranks of climatic factors made it possible to note that the most significant adverse effect is exerted by temperature, humidity and solar radiation in the operating area. Taking into account the distribution of zones of technical rigidity of the climate, its score and the coefficient of continentality, a method is proposed for correcting the frequency of operations of technical service of transport-technological machines for the zone of their actual operation.

Research Progress on Metal-Organic Frameworks by Advanced Transmission Electron Microscopy.

Metal-organic frameworks (MOFs), composed of metal nodes and inorganic linkers, are promising for a wide range of applications due to their unique periodic frameworks. Understanding structure-activity relationships can facilitate the development of new MOFs. Transmission electron microscopy (TEM) is a powerful technique to characterize the microstructures of MOFs at the atomic scale. In addition, it is possible to directly visualize the microstructural evolution of MOFs in real time under working conditions via in situ TEM setups. Although MOFs are sensitive to high-energy electron beams, much progress has been made due to the development of advanced TEM. In this review, we first introduce the main damage mechanisms for MOFs under electron-beam irradiation and two strategies to minimize these damages: low-dose TEM and cryo-TEM. Then we discuss three typical techniques to analyze the microstructure of MOFs, including three-dimensional electron diffraction, imaging using direct-detection electron-counting cameras, and iDPC-STEM. Groundbreaking milestones and research advances of MOFs structures obtained with these techniques are highlighted. In situ TEM studies are reviewed to provide insights into the dynamics of MOFs induced by various stimuli. Additionally, perspectives are analyzed for promising TEM techniques in the research of MOFs' structures.

Assessing the vulnerability of Iran to subsidence hazard using a hierarchical FUCOM-GIS framework

In engineering practice, land subsidence is considered a threat to the infrastructure and lifelines massively distributed globally. In this study, a combined methodology of full consistency decision-making (FUCOM) and the geographical information system (GIS) was employed to assess the vulnerability of Iran to subsidence. Accordingly, a new hierarchical FUCOM-GIS framework was developed. The FUCOM was first used to evaluate the weight of various causative factors. Afterward, the GIS was employed to superimpose several layers to produce a land subsidence susceptibility map (LSSM) of Iran. The results revealed water stress, groundwater depletion, soil type, geological time scale, and rainfall amount as the most significant factors causing land subsidence, while the influence of several additional factors was also investigated. The LSSM was validated against interferometric synthetic aperture radar (InSAR) analyses of the Sentinel-1 for several megacities. Accordingly, Tehran, Qom, Yazd, Isfahan, Kerman, and Mashhad were recognized as the critical regions, delivering a subsidence rate between 15 and 20 cm/yr. Eventually, the assessed hazard for the power transmission lines and substations, as an exemplified lifeline, was confirmed by field reconnaissance. The results revealed the pier sinking, structural members buckling, electric insulators deviation, and cracking as the main damages to the transmission lines.

Methodological Approaches to Assessing the Economic Damage Associated with the Incidence of Hemorrhagic Fever with Renal Syndrome in the Russian Federation

The aim of the study was to develop methodological approaches to assessing the economic damage associated with the incidence of hemorrhagic fever with renal syndrome (HFRS) and to calculate the economic damage by the example of an outbreak of HFRS in the Saratov region in 2019. Materials and methods. The paper analyzes the economic indicators of the Federal State Statistics Service; data on the incidence of HFRS in the Russian Federation for the period of 2019–2022. To calculate the cost of outpatient and inpatient medical care, as well as the costs associated with the medical follow-up of convalescents, the indicators of the Program of state guarantees of free provision of medical care to citizens for 2022 and for the scheduled period of 2023 and 2024 were used. The calculation of economic losses associated with the payment of temporary disability benefits was carried out according to the equation provided in the Federal Law No. 255-FZ dated December 29, 2006 (as amended on October 07, 2022). Economic losses associated with premature death at an economically active age were calculated based on the value of unproduced GDP due to lost years of life in the corresponding age group. Results and discussion. The costs of treatment, rehabilitation and payment of temporary disability benefits for 1 case of HFRS at the age of 0 to 56.5 years for the female population and from 0 to 61.5 years for the male population amount to 140 495 rubles; over the age of 56.5 years for the female population and 61.5 years for the male population – 95 412 rubles, respectively. Each fatal case of HFRS aged 0 to 16 years among the male population costs the state 38 976 231 rubles; among the female population – 34 708 331 rubles; in active working age – the value of economic damage varies depending on the age of the person who died of HFRS. The economic damage of the outbreak of HFRS in the Saratov Region (2019), taking into account the direct expenditures of the healthcare system and indirect losses of the country’s economy amounted to 441 453 432 rubles. It is of note that the structure of the main damage is dominated by indirect losses in the economy caused by the premature death of people in economically active age.

Ballistic penetration damage for hybrid carbon/Kevlar/UHMWPE fiber laminated composites: Experimental and numerical techniques

Hybrid composites incorporate different types of fibers and combine the benefits of different material properties for increasing the ballistic efficiency. Here, ballistic penetration behaviors were investigated for hybrid carbon/Kevlar/UHMWPE fiber laminated composites. The hybrid laminated composites had been prepared and penetrated under fragment simulating projectiles (FSP). The details of complex failure modes for the hybrids are observed and presented to illustrate the failure mechanisms. A finite element (FE) model had been developed to predict the impact induced damages for the hybrid composites. It is shown that the FE predictions were reliable both for failure modes and energy absorption. The damage evolution of the hybrid composites exhibited progressive damage behaviors. The damage area was very localized on the striking face and widened on the exit face of the composites. The main damage modes for fiber breakages, matrix crack and composite delamination can be found in the post-impact morphologies and numerical models. The energy absorption capability can be improved by 16.4% for the hybrid laminates. The stress wave propagation observed in FE models was linked to the hybrid structures and material properties, which resulted in a different damages and energy dissipation mechanisms.

Quality control analysis of Best Fried Chicken (BFC) products in Prabumulih City

The development of an increasingly advanced era requires all business people to innovate, maintain and improve the quality of their respective products. Best Fried Chicken (BFC) is a company engaged in the culinary field that sells fast-food fried chicken products with a partnership system in its business activities. Best Fried Chicken (BFC) Prabumulih City always pays attention to the quality of its products by controlling their quality. However, customers often still need to give more favourable comments about the quality of fried chicken products at Best Fried Chicken (BFC) in Prabumulih City. One way to control product quality is with Statistical Process Control (SPC). This study aims to analyze whether the product quality control at Best Fried Chicken (BFC) in Prabumulih City is still within tolerance limits and to determine the causal factors that affect the quality of the product. The products studied were fried chicken products produced from January 4th to February 2nd, 2023, with the result that the level of damage was still within tolerance limits. According to the cause and effect diagram, the main damage factor is people, methods, and raw materials. The most dominant product damage among the types of scorch damage, inappropriate size, and hard texture is damage to the size that does not match the most dominant causal factors found in humans and methods. Quality control at Best Fried Chicken (BFC) in Prabumulih City can be further improved from all aspects, both humans and the methods used, so that that product damage can be minimized and quality control can run effectively.

Spall damage of solution-treated hot-rolled Inconel 718 superalloy under plate impact

Spallation of a solution-treated hot-rolled Inconel 718 superalloy is investigated via plate impact loading along with ultrafast free-surface velocity measurements. Microstructures of the initial and postmortem samples are characterized with scanning electron microscopy and electron backscatter diffraction. Incipient spallation occurs near a peak shock stress of 5.3 GPa at a tensile strain rate of 105 s−1. Spall strength increases slightly (3.2–3.9 GPa) with increasing peak stress in the explored peak stress range (5.3–17.2 GPa) and tensile strain rate range (1.1 × 105–1.7 × 105 s−1). Ductile fracture is the main damage mode, and void nucleation occurs mostly at grain boundaries and triple junctions. Both intergranular and intragranular voids tend to nucleate preferentially at grain boundaries with a misoriention of 45°–55°. Molecular dynamics simulations are conducted to explain the mechanisms of intergranular and intragranular damage as observed in the experiments.

Features of Project Management of Industrial Enterprise Reconstruction on the Basis of Technical, Economic, Legal and Technological Factors

One of the main forms of industrial enterprise development is reconstruction. The main task is to improve the technical level of the enterprise, the quality of products, introduce energy-saving and resource-saving technologies using existing fixed assets. There is a growing interest in reducing maintenance and repair costs, as well as in significantly increasing the time between repairs and reducing the energy intensity of buildings. This article is devoted to the peculiarities of managing a project for the reconstruction of an industrial enterprise, which includes a cultural heritage site. The study was conducted on the example of one of the oldest enterprises in Russia - Joint Stock Company 'Votkinsky Zavod'. The purpose of this study is to develop a methodological basis for the effective management of the reconstruction of an industrial facility based on a database of the technical condition of the main production assets of the Joint Stock Company 'Votkinsky Zavod'. In the course of the study, a detailed analysis of the historically established fund of buildings and structures, in-cluding a cultural heritage site, was carried out with the aim of their possible most optimal further adaptation. The main periods of the development of the plant in the history of its existence are highlighted. The result of the study is an assessment of the technical condition of buildings and structures of the industrial en-terprise under consideration, the classification of a group of buildings according to the periods of construction, according to design schemes and materials used, as well as according to the main defects and damage to structures. As a result of the study, a list of the most common defects and damages to the building structures of buildings and structures was compiled, and a base of technical information on the state of the enterprise's fixed production assets was formed. An algorithm for choosing the optimal variant of the project for the reconstruction of a building, structure or complex is proposed based on the observance of a certain sequence of economic analysis when considering technical, economic, social, aesthetic and time indicators with comparability of design solutions for reconstruction options.

DYNAMIC COMPRESSIVE PROPERTIES OF ALUMINIUM-MATRIX COMPOSITES REINFORCED WITH SiC PARTICLES

The aluminium-matrix composites (AMCs) consisted of (5, 10 and 15) x/% SiC particles (SiCp) in an aluminium alloy 7055 matrix. Specimens were taken from hot-press sintering. High-strain-rate tests were performed using the split-Hopkinson pressure bar (SHPB) method. The microstructures were observed with a scanning electron microscope (SEM) to understand the damage mechanisms of the SiCp/7055 Al composites at high strain rate. The SHPB test results show that the SiCp-reinforced composites are more sensitive to strain rate than the unreinforced material. The strain-rate sensitivity of the flow stress of these composites increases substantially with the increase of the strain rate. The flow stress of SiCp/7055Al composites with 10 x/% and 15 x/% SiCp at 3000 s–1 first increases and then decreases with the increase of the plastic strains, which was caused by the heat generated during adiabatic compression. Microstructure-characterization results show that SiCp cracking and SiCp/7055Al interface debonding are the main damage mechanisms of the composites. The SiCp volume fraction and strain rate affect the damage of composites during the dynamic compressive deformation of the SiCp /7055Al composites.

A GIS-based flood damage index for cultural heritage

Evaluating potential consequences of floods on cultural heritage is one of the objectives of the 60/2007/EC Floods Directive. Nevertheless, the peculiarities of cultural heritage in terms of data availability, exposure values and vulnerability, make flood damage and risk analyses rarely applied. This work aims at developing a GIS-based Flood Damage Index for Cultural Heritage (FDICH) that (i) weights exposure based on the level of listing, (ii) weights vulnerability based on ad-hoc taxonomy, (iii) provides a damage density per unit surface instead than a point classification. FDICH is intended for large scale applications, e.g., regional or District ones, to identify damage hotspots and support risk mapping and management. The method is applied to the Po River District Authority, the largest in Italy, within a project framework for flood damage analysis of all exposed assets. In the territory of the district, a new spatial database of cultural heritage counting ca. 125,000 items is created and enriched with exposure and vulnerability attributes. The results allow for identifying 5 main cultural heritage damage hotspots and the calculation of FDICH shows the potential for cross-compare damages at District but also al local scales, for prioritization of mitigation measures.

Analysis of damage caused by drop impacts for mulberry fruits: An dropping experiment and numerical simulation

AbstractIn the process of mechanized production of mulberry, falling collision damage is one of the main damage forms, which causes serious damage and accelerates fruit decay. Through the drop collision test and simulation analysis of mulberry fruit, the relationship between drop conditions and fruit damage degree was established, so as to provide reference for reducing fruit falling damage. The drop test is carried out. The relationship between factors and indicators is established. The drop height, fruit plate angle, fruit plate material, and drop direction were taken as factors, and then the energy loss was selected as indicator. The drop process of mulberry fruit is analyzed by numerical simulation, and the maximum stress and deformation of mulberry fruit are analyzed. With the increase of the drop height, the kinetic energy of the fruit increases. When the fruit plate material is pearl cotton, the drop height changes from 200 to 1000 mm, the energy loss of fruit falling increases from 4.42 × 10−0.3 J to 2.14 × 10−0.2 J. When the drop height of fruit is 200 mm, the angle of fruit plate is 30°, and the material of fruit plate is pearl cotton, the minimum energy loss of fruit is 3.39 × 10−0.3 J, the fruit damage was the least. This study can provide a reference to reduce the damage of mulberry fruit in the process of mechanical harvest and transportation.Practical ApplicationsThe existing mulberry harvesting methods are manual harvesting, while the vibration harvesting methods have high harvesting efficiency and serious damage. When the harvesting parts hit the tree trunk, the mulberry fruit will leave the tree and falls onto the fruit‐receiving device in the process of mechanical harvesting. There will be a collision and falling of the mulberry, which may cause serious damage. Therefore, in the process of mulberry fruit harvest, transportation, the falling, and collision damage is the main damage form.At present, there is few research on the drop impact damage test of mulberry fruit. In this study, the effects of mulberry falling direction, fruit plate material and drop height on mulberry damage were discussed by drop experiment. Then, the optimization results were carried out. The change and distribution of stress and strain in the process of collision were analyzed by numerical simulation, and the relationship between falling conditions and damage level was established. It is important to analyze the dynamic characteristics of mulberry in the process of drop. This study can be applied as a reference to reduce mulberry fruit impact damage, and provide a theoretical reference for the design of mulberry vibration harvesting machinery.

Specificity protein 1-mediated ACSL4 transcription promoted the osteoarthritis progression through suppressing the ferroptosis of chondrocytes

BackgroundChondrocytes are the main cell damage type involved in the occurrence and development of osteoarthritis (OA). Ferroptosis has been confirmed to be related to many degenerative diseases. This research aimed to explore the role of Sp1 and ACSL4 in ferroptosis in the IL-1β-treated human chondrocyte cells line (HCCs).MethodsThe cell viability was detected with CCK8 assay. The ROS, MDA, GSH, and Fe2+ levels were assessed with corresponding detecting kits. The Col2a1, Acan, Mmp13, Gpx4 and Tfr1 levels were determined by RT-qPCR assay. Western blot was conducted to evaluate the Acsl4 and Sp1 levels. PI staining was carried out to analyze the cell death. The double luciferase report was conducted to verify the interaction between Acsl4 and Sp1.ResultsThe results showed that IL-1β stimulation elevated the LDH release, cell viability, ROS, MDA and Fe2+ levels and declined the GSH levels in the HCCs. Additionally, the mRNA levels of Col2a1, Acan, and Gpx4 were prominently decreased, while Mmp13 and Tfr1 were prominently elevated in the IL-1β stimulated HCCs. Furthermore, Acsl4 protein levels were upregulated in the IL-1β-stimulated HCCs. Both Acsl4 knockdown and ferrostatin-1 treatment neutralized the role of IL-1β in the HCCs. What’s more, Acsl4 was transcriptionally regulated by Specificity protein 1 (Sp1). Sp1 overexpression enhanced the Acsl4 levels and Sp1 knockdown declined it.ConclusionUpregulation of Sp1 activates Ascl4 transcription and thus mediates the occurrence of ferroptosis. Hence, Acsl4 may be a therapeutic target for intervention of OA.