Metal Forming Research Articles

Numerical investigation of effect of pressure exponent for enhanced Coulomb friction model

The complexity of sheet metal parts has reached a level, that without supporting process planning applications almost impossible to design the process planning. Because technology is sharpened to the limit the slightest disturbance in the production results in a waste product. The lubrication condition used during the sheet metal forming is crucial to the success of production. Therefore, the need to model the resulting tribological system as accurately as possible has become increasingly important. This paper purpose with the physically based measurement of the so-called enhanced Coulomb model material parameter used in AutoForm software and the analysis of its effect.

Mechanisms of biological effectiveness of ionic forms of metals of variable valence in respiratory medicine

Background: The task to develop new drugs containing metals of variable valence requires systematization of our knowledge, experimental and clinical studies. The aim of the study: To investigate the mechanisms of the effectiveness of the mineral complex containing metals of variable valence in the treatment of respiratory diseases, to conduct preclinical trials and clinical testing of a new inhalation mineral solution. Materials and methods: The ability of cerium (III) ions to exhibit reducing properties was demonstrated by carrying out chemical reactions of cerium (III) chloride and sulfate with potassium permanganate in the presence of sodium hydroxide or sulfuric acid (respectively). Preclinical studies of acute toxicity were carried out on laboratory mice and rats in accordance with the rules of bioethics and with generally accepted ethical standards for the treatment of animals, based on the standard operating procedures of the university, which comply with the rules adopted by the European Convention for the Protection of Vertebrate Animals used for research and other scientific purposes (Strasbourg, 1986). Clinical testing of two forms of the mineral complex for inhalation (1. Inhalation solution for nebulizer – Renerium; 2. intranasal spray) was carried out on 6 groups of volunteers in compliance with human rights and the principles of conducting medical research involving a person as a subject, declared on the 18th General Assembly of the World Medical Association (Helsinki, Finland), voluntary informed consent, approved by the local ethical committee. Results: Mineral preparation for inhalation therapy of patients with acute respiratory diseases does not show acute toxicity in preclinical studies on laboratory animals. The mechanism of action of the drug is most likely associated with the regulation of redox reactions at the level of the cell membrane, mitochondria and cell nucleus, which is manifested by anti-inflammatory and regenerative activity in the mucous membrane of the respiratory tract and alveolar apparatus. Both forms of the drug are well tolerated. A pronounced clinical efficacy of the drug Renerium in the form of inhalation through a compressor inhaler was noted in the case of a 5-day course of treatment, 5 ml once a day. Conclusion: Experimental and clinical data have demonstrated pronounced anti-inflammatory and regenerative properties of a new mineral complex based on cerium (III), the mechanism of which is due to the regulation of redox reactions.

Leaching characteristics and environmental impact of heavy metals in tailings under rainfall conditions: A case study of an ion-adsorption rare earth mining area

Following ion-adsorption rare earth mining, the residual tailings experience considerable heavy metal contamination and gradually evolve into a pollution source. Therefore, the leaching characteristics and environmental impact of heavy metals in ion-adsorption rare earth tailings require immediate and thorough investigation. This study adopted batch and column experiments to investigate the leaching behaviour of heavy metals in tailings and assess the impact of tailings on paddy soil, thereby providing a scientific basis for environmental protection in mining areas. The results showed that Mn, Zn, and Pb contents were 431.67, 155.05, and 264.33 mg·kg−1, respectively, which were several times higher than their respective background values, thereby indicating significant heavy metal contamination in the tailings. The batch leaching experiment indicated that Mn and Pb were priority control heavy metals. Heavy metals were divided into fast and slow leaching stages. The Mn and Pb leaching concentrations far exceeded environmental limits. The DoseResp model perfectly fitted the leaching of all heavy metals from the tailings (R2 > 0.99). In conjunction with the findings of the column experiment and correlation analysis, the chemical form, rainfall pH, ammonia nitrogen, and mineral properties were identified as the primary factors controlling heavy metal release from tailings. Rainfall primarily caused heavy metal migration in the acid-extraction form from the tailings. The tailing leachate not only introduced heavy metals into the paddy soil but also caused the transformation of the chemical form of heavy metals in the paddy soil, further exacerbating the environmental risk posed by heavy metals. The study findings are significant for environmental conservation in mining areas and implementing environmentally friendly practices in rare earth mining.

Experimental correlation between bending crack evolution and load-drop criterion in tight-radius three-point bending test with GPa-grade steels

Determining the bending-fracture limit, also referred to as local formability, is crucial for sheet metal forming. However, this is limited by existing methods such as the VDA-238-100 standard due to limitations in its failure criterion based on the punch load. This study addresses this limitation by proposing a quantitative crack-based failure criterion and investigating its relationship to the load-drop point. Along with surface and cross-sectional optical analyses, an integrated line-scanning system for the VDA-238 test is developed, and advanced high-strength steel (AHSS) grades are analysed with yield strengths ranging from 980 to 1500 MPa in both the rolling and transverse directions. The results showed that, while the load-drop point marks a rapid shift in the crack-propagation direction, the true onset of crack initiation occurs earlier, with different patterns for each AHSS and direction. For all the AHSS and directions tested, a crack depth exceeding 1 % of the sheet thickness occurs at 90 % of the switch-off stroke in the VDA-238 test, suggesting an empirical tendency toward microcrack growth for a more accurate evaluation of the local formability based on early cracks.

The metal release and transformation mechanisms of V–Ti magnetite tailings: Role of the alternate flooding and drying cycles and organic acids

V–Ti magnetite tailings (VTMTs) contain various heavy metals, such as Fe, Mn, V, Co, and Ni. The groundwater pollution caused by the tailing metal release has become a local environmental concern. Although studies have demonstrated the influence of alternate flooding and drying cycles (FDCs) on metal form and mobility in minerals, little was known about whether FDCs affect the metal release of VTMTs and the transformation of released metals. This study investigated the metal release kinetics of VTMTs and the metal transformation under FDCs in the absence and presence of acid rain (sulfuric and nitric acids) and bio-secreted organic acids (acetic, oxalic, and citric acids). The results showed that FDCs promoted metal release whether or not acids were present. The maximum released concentrations of V, Mn, Fe, Co, and Ni were as high as 78.63 mg L−1,1.47 mg L−1, 67.96 μg L−1, 1.34 mg L−1, and 0.80 mg L−1, respectively, under FDCs and citric acids. FDCs enhanced the tailing metal release by increasing the metal labile fraction proportion. However, the concentrations of released Fe, Mn, V, Co, and Ni all gradually decreased due to their (co-)precipitation. These precipitates conversely inhibited the subsequent mineral dissolution by covering the tailing surface. FDCs also enhanced the tailings’ porosities by 2.94%–9.94%. The mineral dissolution, expansion and shrinkage, and changes in tension destroyed the tailing microstructure during FDCs. This study demonstrated the low metal pollution risk of VTMTs under FDCs, either in acid rain or bio-secreted organic acids. However, the increase in tailing porosity should be seriously considered as it would affect the tailing pond safety.

Changes in the elemental composition of agrocenosis components on gray forest soil under long-term application of mineral and organic fertilizers

The paper analyzes the elemental composition of soils and plants of agrocenosis on the gray forest soil of Vladimir opolye under long-term application of mineral and organic fertilizers. The content of total and mobile forms of Ni, Cu, Zn, Co, Mn, Fe and the content of these elements in aboveground plant organs, as well as changes in the main agrochemical characteristics that can affect the availability of elements to plants were evaluated. It is shown that the application of mineral fertilizers contributes to soil acidification, increase in the content of organic carbon, mobile forms of phosphorus. At the same time, the variants with joint application of mineral and organic fertilizers are subject to less change of these characteristics, which may be due to the increased buffering capacity of the soil with respect to the components coming with mineral salts, due to the applied organic matter. Introduction of Ni, Cu, Zn, Co, Mn, Fe into agrocenosis with fertilizers (organic and mineral) did not affect the gross content of metals in soil. There was a change in the content of mobile forms of metals in the soil due to changes in agrochemical parameters of soils. Changes in the content of trace elements in plant products were recorded. The reduction of Zn, Cu content in plants on the variants with more intensive use of fertilizers (and with higher yield) is explained by "dilution effect". The low content of Co in the soil and its insufficient supply to the plants must be controlled. The joint use of data on changes in the elemental composition of soils and plants allows better differentiation of experimental variants in the space of principal components when analyzed by this method and is promising for monitoring the consequences of agrogenic load of different degrees. The results obtained can be taken into account in the formation of criteria for assessing the mineral nutrition of plants and fertilizer application rates.

Thermo-Mechanical Numerical Simulation of Friction Stir Rotation-Assisted Single Point Incremental Forming of Commercially Pure Titanium Sheets.

Single point incremental forming (SPIF) is becoming more and more widely used in the metal industry due to its high production flexibility and the possibility of obtaining larger material deformations than during conventional sheet metal forming processes. This paper presents the results of the numerical modeling of friction stir rotation-assisted SPIF of commercially pure 0.4 mm-thick titanium sheets. The aim of this research was to build a reliable finite element-based thermo-mechanical model of the warm forming process of titanium sheets. Finite element-based simulations were conducted in Abaqus/Explicit software (version 2019). The formability of sheet metal when forming conical cones with a slope angle of 45° was analyzed. The numerical model assumes complex thermal interactions between the forming tool, the sheet metal and the surroundings. The heat generation capability was used to heat generation caused by frictional sliding. Mesh sensitivity analysis showed that a 1 mm mesh provides the best agreement with the experimental results of total forming force (prediction error 3%). It was observed that the higher the size of finite elements (2 mm and 4 mm), the greater the fluctuation of the total forming force. The maximum temperature recorded in the contact zone using the FLIR T400 infrared camera was 157 °C, while the FE-based model predicted this value with an error of 1.3%. The thinning detected by measuring the drawpiece with the ARGUS non-contact strain measuring system and predicted by the FEM model showed a uniform thickness in the drawpiece wall zone. The FE-based model overestimated the minimum and maximum wall thicknesses by 3.7 and 5.9%, respectively.

Shape prediction in continuous roll forming of sheet metal based on rigid rolls

The continuous roll forming based on rigid rolls (CRFRR) is an innovative process for rapid fabrication of doubly curved surfaces of sheet metal. The curved parts with different shapes and sizes can be obtained by adjusting the generatrix radius of the two rigid rolls or controlling the rolling reduction. In this paper, the principle of CRFRR is introduced and the process that a 3D surface of sheet metal with positive or negative Gaussian curvature is formed using two rigid rolls is analyzed based on the distribution of exit velocity. The exit velocity of material after the sheet metal passes through the roll gap is decomposed into two portions: a linearly distributed velocity and a very small additional velocity. On the basis of exit velocity decomposition and shallow shell theory, an analytical method for predicting the shape of formed surface in CRFRR process is proposed for the first time. The primary part of curvature of the formed 3D surface in longitudinal direction is determined by the linear portion of exit velocity and that in transverse direction is determined by the generatrix radius of the two rigid rolls. The curvature change in the final shape of 3D surface is induced by the additional portion of exit velocity and it is solved from equilibrium equation of shallow shell. The final curvature of the formed surface is acquired through superimposing the primary curvature and the curvature change. Numerical simulations and forming experiments have been carried out on convex and saddle-shaped parts, and the results confirm the validity and accuracy of presented method.

Characterization of the strain rate sensitivity of basal, prismatic and pyramidal slip in Zircaloy-4 using micropillar compression

The slip strength of individual slip systems at different strain rates will control the mechanical response and strongly influence the anisotropy of plastic deformation. In this work, the slip activity and strain rate sensitivity of the <a> basal, <a> prismatic, and <c+a> pyramidal slip systems are explored by testing at variable strain rates (from 10−4 s−1 to 125 s−1) using single crystal micropillar compression tests. These systematic experiments enable the direct fitting of the strain rate sensitivities of the different slips using a simple analytical model and this model reveals that deformation in polycrystals will be accommodated using different slip systems depending on the strain rate of deformation in addition to the stress state (i.e. Schmid's law). It was found that the engineering yield stress increases with strain rate, and this varied by slip systems. Activation of the prismatic slip system results in a high density of parallel, clearly discrete slip planes, while the activation of the <c+a> pyramidal slip leads to the plastic collapse of the pillar, leading to a ‘mushroom’ morphology of the deformed pillar. This characterization and model provide insight that helps inform metal forming and understanding of the mechanical performance of these engineering alloys in the extremes of service conditions.

Odors Adsorption in Zeolites Including Natural Clinoptilolite: Theoretical and Experimental Studies.

This publication presents the results of combined theoretical and experimental research for the potential use of natural clinoptilolite zeolite (CLI) as an odor-adsorbing material. In this study of adsorption capacity, CLI of various granulation was used and its modifications were made by ion exchange using Sn and Fe metals to check whether the presence of metals as potential active centers does not lead to catalytic processes and may lead to enhanced absorption of odorous substances through their adsorption on the created metallic forms. Additionally, in order to increase the specific surface area, modifications were made in the form of hierarchization in an acidic environment using hydrochloric acid to also create the hydrogen form of zeolite and thus also check how the material behaves as an adsorbent. To compare the effect of CLI as a sorption material, synthetic zeolite MFI was also used-as a sodium form and after the introduction of metals (Sn, Fe). The above materials were subjected to adsorption measurements using odorous substances (including acetaldehyde, dimethylamine, pentanoic acid and octanoic acid). Based on the measurements performed, the most advantageous material that traps odorants is a natural material-clinoptilolite. Depending on the faction, its ability varies for different compounds. In the case of acetaldehyde, an effective material is clinoptilolite with a grain size of up to 2 mm. In the case of carboxylic acids, it is material after hierarchization with a fraction of 3-4 mm. In the case of theoretical calculations, information was obtained to show that metallic centers are more stable above oxygen, which is associated with the skeletal aluminum in clinoptilolite.

Bioavailability and ecological risk assessment of metal pollutants in ambient PM2.5 in Beijing

Metal pollutants in fine particulate matter (PM2.5) are physiologically toxic, threatening ecosystems through atmospheric deposition. Biotoxicity and bioavailability are mainly determined by the active speciation of metal pollutants in PM2.5. As a megacity in China, Beijing has suffered severe particulate pollution over the past two decades, and the health effects of metal pollutants in PM2.5 have received significant attention. However, there is a limited understanding of the active forms of metals in PM2.5 and their ecological risks to plants, soil or water in Beijing. It is essential that the ecological risks of metal pollutants in PM2.5 are accurately evaluated based on their bioavailability, identifying the key pollutants and revealing historic trends to future risks control. A two-year project measured the chemical speciation of pollution elements (As, Cd, Cu, Cr, Ni, Mn, Pb, Sb, Sr, Ti, and Zn) in PM2.5 in Beijing, in particular their bioavailability, assessing ecological risks and identifying key pollutants. The mass concentrations of total and active species of pollution elements were 199.12 ng/m3 and 114.97 ng/m3, respectively. Active fractions accounted for 57.7 % of the total. Cd had the highest active proportion. Based on the risk assessment code (RAC), most pollution elements except Ti had moderate or high ecological risk, with RAC exceeding 30 %. Cd, with an RAC of 70 %, presented the strongest ecological risk. Comparing our data with previous research shows that concentrations of pollution elements in PM2.5 in Beijing have decreased over the past decade. However, although the total concentrations of Cd in PM2.5 have decreased by >50 % over the past decade, based on machine model simulation, its ecological risk has reduced by only 10 %. Our research shows that the ecological risks of pollution elements remain high despite their decreasing concentrations. Controlling the active species of metal pollutants in PM2.5 in Beijing in the future is vital.

Effectiveness of use zeolite in vegetable growing in the footdown zone of southeast Kazakhstan

Natural zeolite from the Shankanay deposit is effective for use as an additive to mineral fertilizers when growing vegetable crops in the foothill zone of south-east Kazakhstan. Zeolite added to the soil with mineral fertilizers leads to an increase in the water-physical properties of dark chestnut soil. The water permeability of these options has increased noticeably. The use of zeolite and fertilizers helps to increase the mobile forms of nitrate nitrogen, mobile phosphorus and exchangeable potassium. The addition of zeolite reduces the concentrations of mobile forms of heavy metals in the dark chestnut soil under study. Thus, the concentration of cadmium in the soil in a 0-20 cm layer under sowing table beets when using 2 tons of zeolite decreased by 50% with a control value of 1.0 mg/kg, which does not exceed the maximum permissible concentration.A positive effect of zeolite fertilizer on the productivity of vegetable crops was revealed, which makes it possible to increase the total yield of table beet roots from 42.8 t/ha in control to 43.3-62.7 t/ha in fertilized variants with an increase in yield from 4.4 t/ha up to 19.9 t/ha. The yield of cabbage was 25.7 t/ha on the control, and increased by 6.5-16.5 t/ha on the fertilized variants. The use of zeolite and fertilizers contributes to the production of vegetables with good and high quality indicators. Application of both zeolite and fertilizers increased the dry matter, sugar and vitamin C content of the studied crops. The amount of nitrates in the products decreased with the addition of zeolite and increased in other variants of the experiment, but did not exceed the maximum permissible concentration. Thus, in the control variant, the nitrate content in cabbage heads was 223 mg/kg wet weight, in the variants with zeolite 2t/ha - 205 mg/kg, in beetroots - 248 mg/kg and 195 mg/kg, respectively.

Geoenvironmetal assessment of different types of cryolithic soils in Western Yakutia under the conditions of diamond-mining operations

The problems of geoenvironmental consequences of mining operations are especially acute in the arctic and subarctic regions, where the spread of permafrost significantly reduces the buffering capacity of landscapes. The article presents data on the content of heavy metals in the soil cover of the transient zone between the middle taiga and north taiga landscapes of Western Yakutia under the conditions of mining operations and assesses the resistance of different types of soils to heavy metals pollution. Field and laboratory works were carried out in August 2022. The heavy metals content was determined by atomic absorption spectrometry. Specialized software was used for analysis, such as MS Excel 2013, Statistica 12.0, and QGis 3.26.1. Calculation of organic forms of heavy metals in soil solutions was performed using the NICA-Donnan model. In the course of studies, the structure of the soil cover in the Nakyn kimberlite field in the conditions of the mining industrial complex operation was determined and a sketch map of the soil cover of the territory was compiled. The geochemical series of the studied heavy metals is as follows according to the degree of concentration of heavy metals in cryolithic soils: Pb &gt; Zn &gt; Ni &gt; Cu &gt; Cd &gt; As &gt; Hg. Positive correlations between humus and Cd, Pb, Zn, as well as the occurrence of synergism in the Pb–Cd, Zn–Pb, Zn–Cu pairs were revealed. The soils organic matter enhances migration of heavy metals. The man-made input of Ni and Zn in cryolithic soils will lead to increase of mobile fraction. Cd is more mobile in pale-yellow carbonate and cryogenic soils. The regional background level of heavy metals for these types of soils was calculated, which can be used in future works when the intensity of mining operations increases.

A Study on Yield Criteria Influence on Anisotropic Behavior and Fracture Prediction in Deep Drawing SECC Steel Cylindrical Cups.

The deep drawing process, a pivotal technique in sheet metal forming, frequently encounters challenges such as anisotropy-induced defects. This study comprehensively investigates the influence of various yield criteria on the anisotropic behavior and fracture prediction in SECC steel cylindrical cups. It integrates Hill'48R, Hill'48S, and von Mises yield criteria in conjunction with Swift's hardening law to evaluate material behavior under complex stress states. Experimental and numerical simulations assess the anisotropy effects across multiple orientations (0°, 45°, and 90°), revealing intricate relationships between stress criteria and material response. The findings indicate significant discrepancies between isotropic and anisotropic models in predicting fracture heights, emphasizing the importance of selecting appropriate yield criteria. Notably, the von Mises criterion results in lower fracture heights, suggesting higher susceptibility to fractures, while the Hill'48R model aligns closely with experimental data, validated through variations in punch corner radius and blank holder force parameters, with a maximum deviation of 3.23%. Hill'48S displays moderate plastic deformation characteristics.

Animal waste as a valuable biosorbent in the removal of heavy metals from aquatic ecosystem-an eco-friendly approach.

Toxic pollutants in the form of heavy metals are added through various anthropogenic activities daily into the aquatic ecosystem beyond their permissible limits, and their bioaccumulation capacity makes them hazardous substances for the survival of all organisms. Thus, their removal from aquatic ecosystems is the need of the hour. Treatment of wastewater containing heavy metals through biosorption is gaining popularity and is being explored all around the world due to its various advantages over conventional methods of treatment. Utilization of animal waste as a biomaterial could be the best solution to remove it from the ecosystem. Such treatment methods are a blessing for developing and underdeveloped countries due to their low cost. This paper provides in-depth details about heavy metals, their health implications, mechanisms of toxicity, modes of transportation, and conventional treatment approaches. A comprehensive understanding of the biosorption process, encompassing its world scenario, evolution, mechanisms, factors affecting the process, and advantages, will also be covered. Finally, animal wastes and their applicability in the removal of heavy metal pollutants from wastewater shall also be thoroughly reviewed, followed by their future utility and recommendations.

Investigation on mechanism in fabricating truncated cone with tooth features of titanium alloy via flexible free incremental forming at room temperature

It has been a challenge to efficiently make titanium alloy thin-walled components by sheet metal forming. Incremental sheet forming (ISF) method provides a promising way to increase the formability of low-ductility metallic sheets, but making titanium alloy sheet panels still needs heating by electricity or laser. The present work investigates the deformation mechanism in fabricating truncated cones of titanium alloy with tooth features realized by flexible free incremental sheet forming (FFISF) at room temperature. Experimental investigations on auxiliary sheets and tool path selections, analytical modeling, finite element simulation, and microstructure characterization have been conducted to evaluate the deformation mechanism in terms of the geometric deviation, thickness distribution and microstructure evolution of TA2 and TC4. Results indicate that the I-O loading path coupled with an optimized auxiliary sheets selection can ensure the successful fabrication of designed panel without defects. An analytical model is proposed to predict the free edge dependent law of thickness distribution in FFISF, indicating the material thinning is positively correlated with the distance from the free edge, while the thinning rate is inversely proportional to the yield strength. A more uniform thickness of TC4 panel is obtained compared with TA2. Finally, the improved formability of titanium alloys by FFISF can be attributed to grain subdivision, decreasing of intragranular deformation, and optimization of dislocation movement.

Simulation and Experimental Approach for Metal Forming with a Multi-Point Die

Multi-point forming (MPF) is considered a flexible and innovative sheet metal forming process that allows for the creation of three-dimensional curved surfaces. This study investigates the effects of various parameters on the final product in metal forming using a multi-point die. The research employs a combination of numerical simulations and experimental work to analyze and minimize defects in the forming process. The concentration is on brass (Cu Zn 65-35) and rubber materials, with specific thicknesses of 0.71 mm and 2 mm, respectively. Although ANSYS 15.0 is used to study the stresses and strains resulting from the formation process with the multi-point die (MPD), the experimental work was conducted to study the effect of two parameters: forming speeds (5 and 15 mm/min) and holding times (1, 3, and 5 minutes were used in this process). The simulation results reveal that the use of rubber significantly reduces defects such as dimples on the sheet surface. Additionally, the presence of rubber helps distribute the force, leading to a reduction in maximum stress and strain in the blank profile to approximately 27% and 49%, respectively, in the second case. The study also explores the impact of forming speed and holding time on spring back. BY measuring the dimensional accuracy of the final products. A forming speed of 5 mm/min and a holding time of 5 minutes resulted in the best outcomes, with a minimum average spring back (0.997). Moreover, the ANOVA algorithm was used to discuss the results which indicated that the forming speed and holding time significantly affect the dimensional accuracy. The research shows that altering settings and adding rubber to multi-point forming improves product quality and accuracy. This study enhances metal forming knowledge and improves industrial processes.

Role of the Microstructure in the Li-Storage Performance of Spinel-Structured High-Entropy (Mn,Fe,Co,Ni,Zn) Oxide Nanofibers

High-entropy oxides with spinel structure (SHEOs) are promising anode materials for next-generation lithium-ion batteries (LIBs). In this work, electrospun (Mn,Fe,Co,Ni,Zn) SHEO nanofibers produced under different conditions are evaluated as anode materials in LIBs and thoroughly characterised by a combination of analytical techniques. The variation of metal load (19.23 or 38.46 wt% relative to the polymer) in the precursor solution and of calcination conditions (700 °C/0.5 h, or 700 °C/2 h followed by 900 °C/2 h) affects the morphology, microstructure, crystalline phase, and surface composition of the pristine SHEO nanofibers and the resulting electrochemical performance, whereas mechanism of Li+ storage does not substantially change. Causes of long-term (≥650 cycles) capacity fading are elucidated via ex situ synchrotron X-ray absorption spectroscopy. The results evidence that the larger amounts of Fe, Co, and Ni cations irreversibly reduced to the metallic form during cycling are responsible for faster capacity fading in nanofibers calcined under milder conditions. The microstructure of the active material plays a key role. Nanofibers composed by larger and better-crystallized grains, where a stable solid/electrolyte interphase forms, exhibit superior long-term stability (453 mAh g−1 after 550 cycles at 0.5 A g−1) and rate-capability (210 mAh g−1 at 2 A g−1).

The accumulation of cadmium and lead in wheat grains is primarily determined by the soil-reducible cadmium level during wheat tillering

The significant increase in cadmium (Cd) and lead (Pb) pollution in agricultural soil has greatly heightened environmental contamination issues and the risk of human diseases. However, the mechanisms underlying the transformation of Cd and Pb in soil as well as the influencing factors during their accumulation in crop grains remain unclear. Based on the analysis of the distribution trend of Cd and Pb in soil during the growth and development stages of wheat (tillering, filling, and maturity) in alkaline heavy metal-polluted farmland in northern China, this study investigated the response mechanism of soil heavy metal form transformation to soil physicochemical properties, and elucidated the main determining periods and influencing factors for Cd and Pb enrichment in wheat grains. The results showed that an increase in CEC and SOM levels, along with a decrease in pH level, contributed to enhancing the bioavailability of Cd in the soil. This effect was particularly evident during the tillering stage and grain filling stage of wheat. Nevertheless, the effects of soil physicochemical properties on bioavailable Pb was opposite to that on bioavailable Cd. The enrichment of Cd and Pb in grain was significantly influenced by soil pH (r = −0.786, p < 0.01), SOM (r = 0.807, p < 0.01), K (r = −0.730, p < 0.01), AK (r = 0.474, p = 0.019), and AP (r = −0.487, p = 0.016). The reducible form of Cd in soil during the wheat tillering stage was identified as the primary factor contributing to the accumulation of Cd and Pb in wheat grains, with a significant contribution rate of 84.5%. This study provides a greater scientific evidence for the management and risk control of heavy metal pollution in alkaline farmland.

Energy efficiency improvement of heavy-load hydraulic fine blanking press for sustainable manufacturing assisted by multi-stages pressure source system

The fine blanking process has the highest forming accuracy in the field of metal forming and its production volume has increased sharply. However, hydraulic fine blanking presses (HFBP) – the core equipment of the fine blanking process, have suffered from significant energy loss due to the inefficient hydraulic system. To enhance the energy efficiency of the hydraulic system, this study introduced a novel approach – a multi-stage pressure source system comprised of distinct pump-accumulator groups, each operating at varied supplied pressures to narrow the mismatch of the installed and demanded power. This adaptive system is capable of automatic adjustments to align with the required pressure, thereby mitigating energy losses while concurrently preserving superior dynamic working performance. First, this study commenced with a theoretical analysis of the system configuration and energy characteristics of HFBP. Subsequently, a comprehensive exploration into the inherent inefficiencies of the hydraulic system is undertaken by formulating a precise energy consumption model. Finally, a novel energy-saving optimization design was carried out on the fast-approaching subsystem. The results demonstrated that the implementation of the proposed system led to a notable reduction of 76.87% in energy loss within the flow-regulating module, and an overall diminution of 13.53% in energy dissipation compared to the conventional system. This study will significantly advance sustainable manufacturing practices within the metal-forming domain by reducing electricity consumption and production cost.