Distribution In Components Research Articles

New augmented reality remote for virtual guidance and education of fracture surgery: a retrospective, non-inferiority, multi-center cohort study.

The demand for telesurgery is rapidly increasing. Augmented reality (AR) remote surgery is a promising alternative, fulfilling a worldwide need in fracture surgery. However, previous AR endoscopic and Google Glass remotes remain unsuitable for fracture surgery, and the application of remote fracture surgery has not been reported. The authors aimed to evaluate the safety and clinical effectiveness of a new AR remote in fracture surgery. This retrospective non-inferiority cohort study was conducted at three centres. Between 1 January 2018 and 31 March 2022, 800 patients who underwent fracture surgery were eligible for participation. The study enroled 551 patients with fractures (132 patellae, 128 elbows, 126 tibial plateaus, and 165 ankles) divided into an AR group (specialists used AR to remotely guide junior doctors to perform surgeries) and a traditional non-remote group (specialists performed the surgery themselves). Among 364 patients (182 per group) matched by propensity score, seven (3.8%) in the AR group and six (3%) in the non-remote group developed complications. The 0.005 risk difference (95% CI: -0.033 to 0.044) was below the pre-defined non-inferiority margin of a 10% absolute increase. A similar distribution in the individual components of all complications was found between the groups. Hierarchical analysis following propensity score matching revealed no statistical difference between the two groups regarding functional results at 1-year follow-up, operative time, amount of bleeding, number of fluoroscopies, and injury surgery interval. A Likert scale questionnaire showed positive results (median scores: 4-5) for safety, efficiency, and education. This study is the first to report that AR remote surgery can be as safe and effective as that performed by a specialist in person for fracture surgery, even without the physical presence of a specialist, and is associated with improving the skills and increasing the confidence of junior surgeons. This technique is promising for remote fracture surgery and other open surgeries, offering a new strategy to address inadequate medical care in remote areas.

Insights into the antagonistic effects of calcium on cadmium accumulation in peanuts (Arachis hypogaea L.)

Peanut (Arachis hypogaea L.) plant has a high requirement for calcium (Ca) during its growth and development, and possesses the ability to accumulate cadmium (Cd) from soil. However, the precise mechanisms underlying the antagonistic effects between Ca and Cd remain unclear. This study aimed to explore the dynamic changes in Cd accumulation in peanut seedlings by varying the Ca-to-Cd concentration ratio (CRCa/Cd) from 250 to 3500. Additionally, the influence of ion channel competition and cell wall fixation in the root on Cd accumulation in peanuts was explored by analyzing Cd chemical forms, subcellular distribution, pectin content, and Cd2+ fluxes using a non-invasive micro-test technique (NMT). The findings revealed that Cd accumulation in peanut seedlings was significantly lower when the CRCa/Cd was higher than 2000. In the Ca-pretreated seedlings (cell wall fixation treatment), Cd content in the shoots and roots decreased by 18.9% and 25.0%, respectively, compared with the simultaneous exposure to Ca and Cd (ion channel competition treatment). Cd2+ influx in peanut roots decreased by 55.8% in the Ca-pretreated group. However, increasing the competitive strength of Ca2+ and Cd2+ did not affect Cd2+ influx under normal Ca conditions (>2 mM Ca). Meanwhile, Ca pretreatment significantly increased Cd distribution in the root cell wall, pectate, and protein-binding forms, while significantly reducing Cd distribution in root soluble components and inorganic Cd forms. The pectin content in the roots increased by 128% and 226% in the Ca and Cd simultaneous exposure treatment and Ca pretreatment, respectively. These results suggest that Ca pretreatment enhanced Cd retention in the root cell wall. Overall, exogenous Ca effectively mitigated Cd accumulation in peanut plants when the CRCa/Cd was below 2000, and Ca2+ channels partially facilitate the entry of Cd2+ into peanut roots. Under normal Ca supply conditions, exogenous Ca reduced Cd accumulation in peanuts primarily through root cell wall fixation rather than ion channel competition. Our findings provide insights into the mechanism by which Ca alleviates the uptake and transfer of Cd in peanuts.

ЧИСЛЕННОЕ ИССЛЕДОВАНИЕ РАБОТЫ УЗЛА МОНОЛИТНОГО БЕЗБАЛОЧНОГО ПЕРЕКРЫТИЯ СО СТАЛЕБЕТОННОЙ КОЛОННОЙ, С ПРИМЕНЕНИЕМ СРЕЗНОГО БАЛОЧНОГО УЗЛА, С УЧЕТОМ СОВМЕСТНОЙ РАБОТЫ БЕТОНА И СТАЛИ

The presented study conducts a comprehensive analysis of the performance of a monolithic slab-column connection utilizing a shear key. Utilizing the finite element method in the ANSYS software suite, a detailed geometric model of the structure is developed, facilitating complex numerical simulations. Special attention is paid to the interaction between concrete and steel within the structure, as well as the transfer of forces through the shear key. The obtained results include a detailed assessment of stress and deformation distribution in various components of the structure, enhancing the overall understanding of its mechanical behavior. The aim of the study is not only to analyze the effectiveness of employing a shear key to ensure the strength and stability of the slab-column connection, but also to generate practical recommendations for optimizing the design to improve the interaction between materials and enhance the reliability of construction projects. The presented research is significant for engineers and designers seeking to improve the processes of design and construction in the modern industry, as well as for developers of regulatory documents in the field of construction and infrastructure. The findings of the study can be applied in the development of new construction technologies.

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

DLP printed 3D gyroid structure: Mechanical response at meso and macro scale

Rapid prototyping (RP) technology enables the fabrication of complex geometries, making lattice structures increasingly popular. Lattice structures, known as cellular materials, have garnered significant attention over the past two decades due to their ability to optimise mass distribution in components. These structures excel in mechanical properties, catering to energy absorption (bending-dominated structures) and structural performance (stretch-dominated structures). In this paper, we investigate the behaviour of stretch-dominated lattice structures using periodic surface models, specifically focusing on sheet-based Gyroid cells, to allow for a more efficient macroscale modelling. We study cells and scaffolds of different sizes, considering various triply periodic minimal surface thicknesses and relative densities ranging from approximately 0.2 to 0.65. We explore load applications in directions different from the unit cell's principal axes and analyse the strain rate effect on both bulk and cellular material. The lattice structures are manufactured using epoxy resin and digital light processing (DLP) technology. In the range of relative density investigated, both in quasi-static and dynamic conditions, a linear trend is observed for Young's modulus and compression yield strength. To extend the quasi-static results to the dynamic regime, we employ a more generalized normalization technique. This approach divides Young's modulus and compression yield strength by the behaviour of the base material at a specific strain rate, facilitating the correlation of mechanical properties across the two loading regimes. Based on experimental findings, we implemented and calibrated a bi-linear material model for describing, in macroscale, triply periodic minimal surface (TPMS) Gyroid structures. The model coefficients are parameterized with respect to relative density. In addition, the presented material law was compared with that proposed by Gibson-Ashby. Furthermore, we evaluated the anisotropy of both the base material and the unit cell. The first one is done by testing the 3D printed samples in directions different from the printing one, the latter by using the Zener factor. The anisotropy evaluation confirmed the isotropic behaviour of the unit cell within the range of relative density and test conditions investigated. Finally, we perform linear elastic 3D macroscopic and mesoscopic model simulations for combined shear-compression tests using the implemented bi-linear material model and the anisotropic stiffness matrix (obtained through the homogeneous formulation) for the macroscale, and the base material for the mesoscopic one. The results demonstrate the suitability of the proposed equivalent material model for studying the TPMS Gyroid structure in the elastic regime, both in quasi-static and dynamic states. This allows for an efficient FE modelling process of complex lattice structures.

CFD–DEM Simulation of Heat Transfer and Reaction Characteristics of Pyrolysis Process of MSW Heated by High-Temperature Flue Gas

Pyrolysis is a promising disposal method for municipal solid waste (MSW) due to the high-value utilization of the organic components of MSW. Traditional indirect heating has low heat transfer efficiency and requires an increase in the heat exchange area. In this study, a refined numerical simulation model for the pyrolysis of four typical MSW components with high-temperature flue gas was established to study the influence of flue gas on the heat transfer and reaction characteristics of MSW. The temperature distribution and particle size change in different components were obtained, and the effects of flue gas temperature and velocity on the pyrolysis process were analyzed. It was found that the temperature difference of the four components along the bed height direction was about 1.36–1.81 K/mm, and the energy efficiency was about 55–61%. When the four components were uniformly mixed, the temperature increase rates of each component were similar during the pyrolysis process. As the flue gas temperature increased, the amount of gas consumption decreased and the energy efficiency increased. When the flue gas velocity increased, the flue gas consumption increased and the energy efficiency decreased. The research results are of great significance for the promotion and application of pyrolysis technology to MSW with high-temperature flue gas.

Experimental investigations and numerical simulations of lattice structures obtained by additive manufacturing

In this study, both experimental and numerical investigations are carried out on samples fabricated by additive manufacturing (AM). The determination of stress distribution in parts obtained by AM, even for simple tensile test, is complicated because it is largely influenced by many manufacturing parameters as the adopted infill pattern, the infill orientation and the infill density. Firstly, the material parameters of the fused filament PLA and tensile specimens made by the AM with an infill grid pattern with density of 100% are experimentally determined. Then, the effect of the infill orientation with an infill density of 40% on the tensile stress state is experimentally and numerically investigated. By synthesizing these results, a comprehensive understanding of stress distribution in AM-produced components is achieved. The obtained anisotropic mechanical parameters are used to simulate compression of a flat-ring part.

Research on the distribution of harmful substances in automotive products based on chemical quantitative

At present, China's automotive industry lacks standardized standards and testing methods for conducting harmful substance testing and evaluation of products.This article finely disassembled a passenger car model and conducted detection and analysis of harmful substances. More than 320000 materials were tested, involving 85 assembly components. This article studies six harmful substances in automotive materials, including lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated biphenyl ethers. The content of harmful substances and their distribution in different materials and components are analyzed. This article provides technical reference for conducting hazardous substance assessments in the automotive industry through data analysis. The harmful substance mainly contained in the studied automotive product is lead, which is mainly distributed in materials such as copper alloys, aluminum, steel, solder, plastics, etc. The content of mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated biphenyl ethers in automobiles is generally low.

On the effect of the core boundary power distribution on the radiation situation in reactor components

The assessment of the neutron flux distribution in nuclear power plant components, like reactor internals and the pressure vessel, is one of the most important parts of their residual lifetime evaluation process because the irradiation damage of these components is strongly dependent on it. The fast neutron fluences in power reactors are generally determined using calculations and verified by measurements. Discrepancies between them sometimes occur, which can be caused by be the inaccuracies in the power distribution used in neutron transport calculations. This paper quantifies the effect of uncertainty in power density on the neutron fluences behind the reactor pressure vessel (RPV). An increase in power density was experimentally simulated by implementing a higher uranium enrichment of certain selected pins. The experiment was also simulated using the MCNP code with the ENDF/B-VII.1 library. Both the experimental and calculational data show a significant local increase in neutron flux. Even behind the RPV, the increase is as high as 25%, while the local power increase in the perturbed pins is about 70–80%, which is approximately equal to the 2 σ power density uncertainties. A good agreement between measurement and calculation was found.

Towards a more realistic MELCOR model for a dry cask for spent nuclear fuel. Part I: sensitivity studies.

The United States (US) Department Of Energy (DOE) has addressed the thermal analysis of the Spent Nuclear Fuel (SNF) stored within a dry cask system as a matter of high priority. In this regard, it is of utmost importance that simulation tools effectively reproduce the general thermal behavior of the modelled cask, including heat exchange and removal. Temperature distribution in the different components of the system is usually the focus of performed thermal analyses. In particular, attention is paid to the maximum temperature reached in the fuel cladding, namely the Peak Cladding Temperature (PCT). Within this framework, the present paper is the first of a two-paper series aimed at developing a more accurate model for the HI-STORM 100S cask. The dry cask in question is modelled and its behavior is simulated by means of the MELCOR code (version 2.2.18019). Stressing the need for a more realistic model rather than a conservative one, this paper reports the efforts undertaken to evaluate the influence of some specific modelling choices on the PCT. The study of the cask performance is therefore conducted taking into consideration three main factors: the axial power distribution in the Fuel Assembly (FA), the flow losses in the air gap between the internal canister and the external overpack, and the conductivity of the overpack concrete.

Development and Validation of a Segregated Conjugate Heat Transfer Procedure on a sCO2 Dry Gas Seal Test Bench

Abstract Carbondioxide at supercritical state shows particularly favorable thermodynamic properties for closed-loop Brayton and Rankine cycles. High density, close to a liquid, and low viscosity, close to a gas, drive to achieve higher energy conversion efficiency with smaller size turbines and components. Since minimizing the sCO2 leakage flows drives to a further increasing of overall efficiency, dry gas seals (DGS) are considered as a key enabling technology for achieving this purpose and for achieving a carbon footprint in line with the increasingly stringent targets. DGSs are gas-lubricated, mechanical, noncontacting, end-face seals, consisting of a mating (rotating) ring and a primary (stationary) ring. The operating equilibrium clearance of the seal is determined by the balance of opening dynamic forces, mainly depending on angular velocity and grooves shape, and closing forces caused by pressure gradients and spring force. Due to high rotational speeds, typical small size sealing gaps (order of magnitude of Micron), high fluid pressure and density, the heat generated by friction through the seal has a large impact on the temperature distribution, therefore a thermal design is needed to stay below the seal allowable temperature; this requirement has been even amplified in the last years with the DGS application to hot turbomachinery. Nowadays, numerical conjugate heat transfer (CHT) analysis is a good industrial practice to quantify the thermal distribution in turbomachinery components. On the other hand, due to different order of magnitude of secondary flows cavity sizes and DGS seal gaps, simulating the whole fluid domain with three-dimensional (3D) computational fluid dynamic (CFD) calculation could drive to prohibitive computational costs. In this regard, this paper presents a fast numerical iterative procedure based on a commercial one-dimensional flow network modeler (altair flow simulator), with real gas effects included, coupled with a commercial finite element solver (ansys mechanical). Additional 3D CFD simulations are carried out to enhance the predictability of the fluid solver in specific critical areas. The proposed procedure is applied and validated in a DGS specific test bench designed, owned and operated by Flowserve. The validation dataset has been generated operating the DGS in the test bench at 15 different conditions in terms of angular velocity and housing temperature with sCO2 as working fluid aligned with those expected on the unit. Test rig consists of a rotor and housing where the turbomachine operating condition (pressure, speed, temperature and sealing fluid) are mirrored to verify the seal performance. The rig is equipped with test seal and a plug seal mounted in a back-to-back configuration. Data set used for this comparison is composed by thermocouples on the statoric rings, retainers and housing of each seal, operating at five different angular speeds and three minimum levels of housing temperature (100 °C, 210 °C, and 250 °C). These temperatures are designed to mirror turbomachinery conditions around the seal, and, if friction heat is not enough to guarantee them, a series of 18x1 kW heating elements circumferentially distributed in the test bench housing, are activated. The nominal operating condition has been considered as the starting point of the model predictions and, there, several sensitivity analyses have been carried out to align the model to test bench measurements; then, the selected configuration has been frozen and used to assess the model performance on other operating conditions. The numerical results have shown a good agreement with experimental data at each operating condition in terms of punctual temperatures previously described and with extremely low computational times.

Non-contact characterization of material anisotropy of additive manufacturing components by electromagnetic acoustic resonance technique

Abstract The degree of material anisotropy in additive manufacturing (AM) components is greatly influenced by the AM process parameters and machine setup. It is crucial to develop an effective technique for evaluating the material anisotropy in AM components to optimize AM process parameters and component design. This paper proposed a non-contact ultrasonic characterization method using the electromagnetic acoustic resonance technique to characterize the anisotropy of AM components. Various electromagnetic acoustic transducers (EMATs) were designed and utilized to characterize the material anisotropy and to determine the principal direction of the AM components. The degree of anisotropy in AM components was characterized using radial radiation EMATs. The relationship between the degree of anisotropy and the laser scanning angle was explored and further determined through the acoustic birefringence factor. Experimental results demonstrated that the anisotropy of AM components is intricately associated with the laser scanning angle, and specific angles can render the AM components isotropic. Moreover, understanding the principal directions is of significance for structural design and analyzing stress distribution in anisotropic components. Therefore, the principal directions of AM components were obtained by rotating the linear polarization EMAT. Changes in the resonance spectrum captured by the linear polarization EMAT while evaluating of principal directions were clearly illustrated, despite negligible alterations in linear ultrasonic features. Metallographic diagrams further validated the experimental findings. This investigation presented a highly accurate and reliable alternative for characterizing the anisotropy of AM components.

Eisenia fetida impact on cadmium availability and distribution in specific components of the earthworm drilosphere.

Although the potential of vermiremediation for restoring metal-contaminated soils is promising, the effects of earthworms on the availability of soil metals are still debatable. Most previous studies considered the soil as a "whole black box." Mobilization or immobilization of metals are affected by earthworm activities within drilosphere hotspots under different soil conditions, which has not been specifically studied. Therefore, an improved 2D terrarium was designed to study the impact of earthworm activities on cadmium (Cd) fate in the drilosphere hotspots (burrow wall soils, burrow casts, and surface casts) of different artificially spiked Cd treatments (CK: 0 mg kg-1; LM: 1 mg kg-1; and HM: 5 mg kg-1) with different organic amendments (2% and 10%). The results revealed that Cd increased earthworm activities with the highest cast production in HM and the highest burrow length in LM. Earthworms exhibited a stronger tendency to reduce total Cd concentration by 4.48-13.58% in casts of LM soils, while 3.37-5.22% in burrow walls under HM treatments. Overall, earthworms could increase the availability of Cd in casts under all conditions (55.46-121.01%). The organic amendments decreased the total Cd concentration and increased the availability of Cd in the disturbed soil. A higher amount of organic amendment significantly decreased total Cd concentration of the drilosphere by 1.16-5.83% in LM and HM treatments, while increasing DTPA-Cd concentrations in all components by 23.13-55.20 %, 14.63-35.11%, and 3.30-11.41% in CK, LM, and HM treatments, respectively, except for earthworm non-disturbed soil and no-earthworm soil in HM treatments. Redundancy analysis (RDA) revealed that the moisture, pH, and total carbon contents in soil are the main factors affecting Cd bioavailability. In this study, we decoded the "black box" of soil by making it relatively simple to better understand the effects and mechanisms of earthworm activities on soil metal availability and consequently provided comprehensive insights for using earthworms in soil vermiremediation.

Mechanical Behavior and Sealing Performance Study of Subsea Connector Core-Sealing Components under the Combined Action of Internal Pressure, Bending Moment, and Axial Load

A complete subsea production system (SPS) is assembled by interconnecting subsea manufacturing facilities through subsea connectors. To ensure the reliability and longevity of the SPS, it is imperative to thoroughly investigate the mechanical behavior and sealing performance of the subsea connector’s core-sealing components. In this study, the loading conditions of the subsea clamp connector are examined to analyze the load transfer relationship between its components under different modes. A mathematical model for the load transfer between locking torque and sealing contact pressure is developed for the preloading mode, and the concept of mechanical transfer efficiency is introduced. Another mathematical model for the load transfer between the locking torque and the design pressure is developed for the operation mode. Furthermore, a three-dimensional full-size finite element model of the subsea clamp connector is established to analyze the effects of complex loads on the mechanical behavior and sealing performance of its core-sealing components. The simulation results indicate that internal pressure loading positively affects the sealing of the subsea connector, and that the stress distribution in the core-sealing components under bending moment loading exhibits significant asymmetric characteristics. Additionally, the superposition of axial tensile loads reduces the effect of the bending moment on the strength of the core seal member but further weakens the seal. Finally, an experimental system is designed to validate the simulation results.

Influence of flaw distribution on tensile behavior of Engineered Cementitious Composites (ECC) based on flaw probability model

The high ductility of Engineered Cementitious Composites (ECC) is attributed to the internal fibers’ bridging effect during matrix cracking, where the distribution of strength in components is crucial for ductility design. Starting from fracture mechanics, this paper proposes a method based on the bridging model to convert flaw sizes into fracture strength in an ECC system. The distribution of flaws in the components is implemented using the Weibull function. By incorporating a crack tracing algorithm, the tensile behavior of components under different flaw distributions is calculated. The effectiveness of the proposed model, which considers flaw distribution, is verified through the comparison between the simulated and experimental data. Furthermore, the simulation results indicate that moderate adjustment on the flaw distribution in components can greatly improve the corresponding tensile ductility without compromising the strength. The research outcomes benefit to provide technical supports for the optimization design of material ductility.

Socket shield technique: Stress distribution analysis.

To analyze through finite element analysis the stress distribution in peri-implant bone tissues, implants, and prosthetic components induced by the socket shield (SS) technique in comparison to other techniques used to treat tooth loss. A three-dimensional model of a superior central incisor crown supported by implant was modeled and three different placement conditions were simulated: SS - 2.0-mm-thick root dentin fragment positioned between the alveolar buccal wall and implant; heterologous bone graft (HBG) - bovine bone graft positioned the alveolar buccal wall and implant; and control (C) - implant fully placed in bone tissue of a healed alveolus. The model was restricted at the lateral surfaces of the bone tissue and the following loads were simulated: Both oblique (45°) loads of 100 N on the lingual surface of the crown (maximal habitual intercuspation) and 25.5 N on the incisal edge of the crown (tooth contact during mandibular protrusion) were simultaneously applied. Tensile stress, shear stress, compression, and displacement were analyzed in the cortical bone, trabecular bone, dentin root fragment, and bone graft; while equivalent von Mises stresses were quantified in the implant and prosthetic components. Stress values of SS and HBG in the bone tissues were higher than C, while slight differences within models were observed for dentin root fragment, bone graft, implant, and prosthetic components. The SS technique presented the highest stress concentration in the peri-implant tissues.

Absorption, metabolism and distribution of carbosulfan in maize plants (Zea mays L.).

The insecticide carbosulfan is usually applied as a soil treatment or seed-coating agent, and so may be absorbed by crops and pose dietary risks. Understanding the uptake, metabolism and translocation of carbosulfan in crops is conducive to its safe application. In this study, we investigated the distribution of carbosulfan and its toxic metabolites in maize plants at both the tissue and subcellular levels, and explored the uptake and translocation mechanism of carbosulfan. Carbosulfan was mainly taken up by maize roots via the apoplast pathway, was preferentially distributed in cell walls (51.2%-57.0%) and most (85.0%) accumulated in roots with only weak upward translocation. Carbofuran, the main metabolite of carbosulfan in maize plants, was primarily stored in roots. However, carbofuran could be upwardly translocated to shoots and leaves because of its greater distribution in root-soluble components (24.4%-28.5%) compared with carbosulfan (9.7%-14.5%). This resulted from its greater solubility compared with its parent compound. The metabolite 3-hydroxycarbofuran was found in shoots and leaves. Carbosulfan could be passively absorbed by maize roots, mainly via the apoplastic pathway, and transformed into carbofuran and 3-hydroxycarbofuran. Although carbosulfan mostly accumulated in roots, its toxic metabolites carbofuran and 3-hydroxycarbofuran could be detected in shoots and leaves. This implies that there is a risk in the use of carbosulfan as a soil treatment or seed coating. © 2023 Society of Chemical Industry.

Heavy metal distribution in wheat plant components following foliar Cd application

Atmospheric deposition of Cd, from anthropogenic activities, can be directly deposited onto and absorbed into wheat plants, yet, how foliar absorbed Cd is translocated in wheat plants is not well understood. A pot experiment investigated foliar Cd application on the accumulation and distribution of heavy metals in various wheat parts. Wheat was grown in a Cd/heavy metal contaminated soil, and from grain heading to the filling stage, 0, 10, 20, 30 and 40 mg kg−1 Cd solution was sprayed repeatedly on leaves (grain heads were covered). Foliar Cd application had no effect on grain yield and Cd concentration (3.01–3.51 mg kg−1 for all treatments), while increased flag leaf blade and sheath Cd concentrations by 1.06–2.77 and 0.00–0.66 times, respectively. Cadmium concentration in the center of the peduncle, from the 40 mg kg−1 Cd solution treatment, was 1.41 times that of the control (10.3 vs 7.30 mg kg−1). Foliar Cd application also increased Cd accumulation (concentration × mass) of the flag leaf blade and sheath. Rachis and grain Pb concentrations were reduced, while stem Pb concentration was increased by Cd application. Cadmium application negatively affected whole plant Ni accumulation and concentration of certain wheat parts; Ni absorption inhibition may have occurred in roots via the downward transport of Cd. Overall results implied that the predominant portion of foliar applied Cd was retained in leaves, while lesser portions migrated to peduncle or root and affected the absorption/distribution of other metals in wheat plants. These results are important for further discerning the mechanism of wheat grain Cd accumulation, especially when grain is raised in areas where atmospheric deposition of Cd (e.g., near smelting facilities) is an issue from an environmental and human health perspective.

GA-based optimization to control the thickness distribution in components manufactured via superplastic forming

Superplastic forming (SPF) is a net-thinning sheet metal forming process that allows to achieve very complex geometries; nevertheless, due to its deformation mechanics, it is difficult to achieve a uniform thickness distribution in the final component since the most stretched regions of the blank are contemporarily characterized by the most severe thinning. With the aim of proposing a robust approach, a new methodology able to optimize the thickness distribution in components produced by SPF is proposed. Although two different titanium-based (Ti-6Al-4 V ELI) axisymmetric components – i.e., a hemisphere and a frustum of cone – were chosen as case studies, the methodology can be extended to any material and to any geometry, even considering more than one objective function. The superplastic forming was numerically simulated, and the Finite Element (FE) model was embedded into an automatic procedure managed by the multi-objective genetic algorithm MOGA-II. The blank's initial thickness distribution was modelled using a second-order polynomial function and its coefficients were determined to get, at the end of the SPF process, a uniform thickness in the formed part irrespective of the specific geometry. Titanium blanks were machined on a 5-axis milling machine to obtain the calculated optimal initial thickness distribution; subsequently, such blanks were superplastically formed and inspected in order to measure the thickness distribution. Tests showed a very good fitting with the numerical prediction thus confirming the robustness and the effectiveness of the proposed methodology.

Estimation of Anchor Capacity in Net Protection System with Brake Frame for Debris Flow Based on Impact Energy

New energy absorption devices have been developed for use in net-type debris flow protection systems. The capacity of the anchors in the system needs careful analysis because the anchors play a significant role in transmitting energy from the impacting debris to the ground. In this paper, an effective method is proposed for estimating the anchor capacity based on increasing energy levels and the effect of brake frames in the system. For this purpose, four test cases based on varying impact energy levels were developed and full-scale impact tests were performed. The maximum deformations and tensile forces developed in the system were recorded and analyzed. Thereafter, the performance of the net protection system in the presence and absence of brake frames was numerically analyzed using ABAQUS software, and the stress distribution in various system components was investigated. Based on the results of the full-scale impact tests and numerical analysis, a relationship between the total anchor capacity and impact energy level was established by considering the workability of the U-clips. This study demonstrates that approximately 40% reduced anchor capacity can be safely used for impact energy levels ranging from 50 to 200 kJ when brake frames are used in the system.