Deposition Efficiency Research Articles

Hybrid additive manufacturing of ceramic/aluminum-titanium gradient composites via arc and laser cladding eutectic pools

ABSTRACT There is a great deal of interest in improving the efficiency of arc-directed energy deposition (Arc-DED) of aluminium matrix composites and the uniform introduction of reinforcing particles. In this work, ceramic/aluminum-titanium gradient composites were manufactured by hybrid additive manufacturing with arc and laser cladding eutectic pools. The results show that the laser cladding powder feed method can have a higher powder capture rate compared to bypass feeding. Coupling the laser and powder changed the pulsed base-arc characteristics and increased the peak arc length. After the addition of the powder mixture, the aluminium matrix formed an Al3Ti reinforced phase, which evolved from needles to rods as the amount of powder increased. As the content of ceramic particles and the Al3Ti phase increased, the average hardness of the AMC components increased from 55.5–126 HV0.1 and the wear rate decreased from 6.16 × 10−3–1.25 × 10.−3 mm3·N−1·m−1.

Prediction of catchment efficiency in direct energy deposition using dimensional analysis and machine learning

Direct Energy Deposition (DED) is an additive manufacturing process used to fabricate thin/thick-walled structures and high-value component restorations. As blown powder-based DED gains prominence, catchment efficiency becomes imperative for enhancing material utilization and process effectiveness. This study focuses on predicting catchment efficiency within a DED process by investigating four significant process parameters: laser power, powder feed rate, carrier gas flow rate, and deposition speed. The primary objective is to devise a dimensionless number capable of predicting catchment efficiency based on a combination of these parameters, categorizing efficiency into low, medium, and high regions. This approach reduces the need for resource-intensive experimentation. The experimental validation of the proposed dimensionless number was conducted, showing an error rate of around 8%. Additionally, six machine learning classifier algorithms – Support Vector Machines, K-Nearest Neighbours, Decision Tree, Random Forest, Linear Regression, and Gaussian Naive Bayes – were employed to categorize catchment efficiency zones. Support Vector Machine demonstrated the best performance with a predictive accuracy of 0.98. This study provides a methodology for catchment efficiency prediction, enhancing decision-making and resource optimization, and can be used to optimize process parameters for thin-wall or relatively thin-wall fabrication.

Prediction of Transport and Deposition of Porous Particles in the Respiratory System Using Eulerian-Lagrangian Approach.

Deep lung delivery is crucial for respiratory disease treatment. Although nano and submicron particles exhibited a good deposition efficiency in deep regions of the lung, powder nonuniformity and particle agglomeration reduce their efficiency. Inhalation of porous particles (PPs) can overcome the mentioned challenges due to their larger size and low-density. The present study numerically investigates the deposition and penetration efficiency of orally inhaled PPs. A revised drag coefficient was implemented for PP transport. A realistic mouth-throat to the fifth generation of the lung was reconstructed from CT-scan images. A dilute suspension of uniformly distributed particles was considered at three inhalation flow rates (15, 30, and 45 L/min). Governing equations of the flow field and particle transport are solved using an Eulerian-Lagrangian approach. The results demonstrate that inhaling PPs significantly reduces the total and regional deposition of particles. There was also a critical porosity value under moderate and high inhalation flow rates for large PPs. Below this critical value, PP deposition efficiency substantially decreases. Additionally, it was also found that under low inhalation flow rates, the impact of porosity value is negligible. Almost 95% of the PPs penetrate the lower branches. These findings provide particle engineers and pharmaceutics with profound insight into developing novel inhalation techniques and drug delivery methods for deep lung delivery.

Analysis and Optimization of Super Duplex Stainless Steel Deposition in Wire Arc Additive Manufacturing Using Machine Learning Techniques

<div>This article presents experimental investigations and machine learning-based analysis on depositions of super duplex stainless steel (SDSS ER2594) material in wire arc additive manufacturing (WAAM) considering the process parameters namely voltage, wire feed rate, torch travel speed, and gas flow rate. Deposition efficiency and surface height values of the accumulated material were measured to build machine learning models using artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS). The developed ANN model could predict the deposition efficiency and surface height with mean absolute deviations (MADs) of 8.9% and 16.1%, respectively. The MAD for prediction of the two responses for ANFIS model was found to be 6.1% and 14.9% as compared to the experimental data. Multi-objective optimization was also performed to obtain optimal solutions to achieve desired deposition results. Mechanical properties and microstructures of the deposited materials with optimal processing parameters were found comparable to that of the base materials.</div>

Multi-scale modeling of aerosol transport in a mouth-to-truncated bronchial tree system

Computational fluid particle dynamics (CFPD) is widely employed to predict aerosol transport in a truncated bronchial tree model on account of its capacity to reveal details of flow field and particle movement. However, setting a physiologically consistent boundary condition in the CFPD for the idealized or image-based truncated bronchial tree model is still a challenge. This paper proposes a multi-scale modeling method, which contains an Extend-Bronchial tree-Network (EBN) boundary condition for a mouth-to-truncated bronchi system. The comparison between EBN boundary condition and a commonly used uniform pressure (UP) boundary condition is conducted. Subsequently, EBN method is used to study the nano-micron (100nm-10μm) particles transport in the mouth-to-truncated bronchi model at different inhalation volume rates (15, 60, 90L/min). Results show that EBN method is more physiologically rational and two methods differ in flow distribution in lobes, vortex structure, and particle transport. The maximum difference in flow rate distribution in lobes between two methods is about 20%, while the maximum relative disparity of particle penetration fraction from lobes and deposition fraction in the TLB is about 93% and 30%, respectively. Meanwhile, this paper reveals the variation of deposition fraction and penetration fraction with the changes in particle diameter and inhalation volume. Deposition efficiency, deposition hotspots and deposition mechanism are also analyzed with inlet Stokes number (Stk) and Reynolds number (Re). This research establishes a foundation for the simulation of aerosol transport in a whole respiratory tract and provides references for inhalation drug delivery and air pollutant management.

Machine learning-enhanced stochastic uncertainty and sensitivity analysis of the ICRP human respiratory tract model for an inhaled radionuclide

The International Commission on Radiological Protection (ICRP) has developed the reference Human Respiratory Tract Model (HRTM), detailed in ICRP Publications 66 and 130, to estimate the deposition and clearance of inhaled radionuclides. These models utilize reference anatomical and physiological parameters for particle deposition (PD). Biokinetic models further estimate retention and excretion of internalized particulates, aiding the derivation of inhalation dose coefficients (DC). This study aimed to assess variability in deterministic131I biokinetic and dosimetry models through stochastic analysis using the updated HRTM from ICRP Publication 130. The complexities of the ICRP PD model were reconstructed into a new, independent computational model. Comparison with reference data for total PD fractions for reference worker, solely a nose breather, covering activity median aerodynamic diameters from 0.3μm to 20μm, showed a 1.04% relative and 0.7% absolute difference, demonstrating good agreement with ICRP deposition fractions. The deterministic DC module was reconstructed in Python and expanded for stochastic analysis, systematically expanding deposition components from HRTM and assigning probability distribution functions to uncertain parameters. These were integrated into an in-house stochastic radiological exposure dose calculator, utilizing latin hypercube sampling. A case of an occupational radionuclide intake was explored, in which biodistribution and committed effective DC (CEDC) were computed for131I type F, considering a lognormal particle size distribution with a median of 5μm. Results showed the published ICRP reference CEDC marginally exceeds the 75th percentile of observed samples, with log-gamma distribution as the best-fit probability distribution. A Random Forest regression model with SHapley Additive exPlanations was employed for sensitivity analysis to predict feature importance. The analysis identified the HRTM particle transport rates scaling factor, followed by the aerodynamic deposition efficiency in the alveolar interstitial region as the most impactful parameters. This study offers a unique stochastic approach on inhaled particulate metabolism, enhancing radiation consequence management, medical countermeasures, and dose reconstruction for epidemiological studies.

On the Role of Substrate in Hydroxyapatite Coating Formation by Cold Spray

The deposition of agglomerated hydroxyapatite (HAp) powders by low-pressure cold spray has been a topic of interest in recent years. Key parameters influencing the deposition of HAp powders include particle morphology and impact kinetic energy. This work examines the deposition of HAp powders on various metal surfaces to assess the impact of substrate properties on the formation of HAp deposits via cold spray. The substrates studied here encompass metals with varying hardness and thermal conductivities, including Al6061, Inconel alloy 625, AISI 316 stainless steel, H13 tool steel, Ti6Al4V, and AZ31 alloy. Single-track experiments offer insights into the initial interactions between HAp particles and different substrate surfaces. In this study, the results indicate that the ductility of the substrate may enhance HAp particle deposition only at the first deposition stages where substrate/particle interaction is the most critical factor for deposition. Features on the substrate associated with the first deposition sprayed layer include localized substrate deformation and the formation of clusters of HAp agglomerates, which aid in HAp deposition. Furthermore, after multiple spraying passes on the various metallic surfaces, deposition efficiency was significantly reduced when the build-up process of HAp coatings shifted from ceramic/metal to ceramic/ceramic interactions. Overall, this study achieved agglomerated HAp deposits with high deposition efficiencies (30–60%) through single-track experiments and resulted in the preparation of HAp coatings on various substrates with thickness values ranging from 24 to 53 µm. These coatings exhibited bioactive behavior in simulated body fluid.

Investigation of inter-subject variation in ultrafine particle deposition across human nasal airways: A study involving children, adults, and the elderly

The airflow and particle dynamics in adult nasal airways have been extensively investigated, but the impact of age-related anatomical changes in children and the elderly remains underexplored. This study systematically investigates age-related anatomical variations and associated influence on nasal airflow dynamics and ultrafine particle deposition characteristics by using Computational Fluid-Particle Dynamics (CFPD) approach. Numerical simulations were conducted for 9 healthy nasal subjects spanning a wide age range. 6 Nasal subjects from the Development Group were used as the primary models for data analysis and deposition correlation development, while 3 subjects from the Validation Group were used to validate the reliability of the derived total and subregional deposition correlations. Our results reveal distinctive variations across age groups. Specifically, the elderly and children exhibit unique patterns that differ from those of young adults. While total deposition efficiency differs significantly between children and adults, filtration efficiency in the subregion with most deposition, main respiratory, remains consistent. Lastly, overall and subregional empirical equations for deposition efficiency were developed by incorporating the combined diffusion parameter, Sca∆b, corroborating the use of geometrical characteristic parameters for each specific subject in predicting nasal deposition efficiency across different age groups. Our findings are expected to improve the predictive nanoparticle exposure analysis in nasal airways across different age groups, thereby improving the respiratory health for individuals throughout the life span.

Improving bond strength and deposition efficiency of ceramic coatings via low pressure cold spraying: A study on hydroxyapatite coatings with Cu-Zn blends

This study presents Low Pressure Cold Spraying (LPCS) method for ceramic coatings, aimed at enhancing efficiency and elucidating bonding mechanisms. It focuses on the deposition of ceramic coatings using LPCS, with hydroxyapatite (HA) on 316L stainless steel (SS) as an illustrative example. Despite the advantages of LPCS, retaining HA particles has proven challenging, resulting in thin coatings (11.09 ± 2.56 μm) with low bonding strength (1.80 ± 0.19 MPa). To address this issue, a composite coating strategy was developed by blending 20 wt% Cu and Zn powder with 80 wt% HA. This approach significantly improved coating properties, achieving enhanced bonding strength (33.70 ± 1.13 MPa), deposition efficiency (27 %), and hardness (136.30 ± 2.45 HV) compared to pure Cu-Zn coatings. Numerical simulations were conducted to interpret these experimental results, indicating that blending metal with HA improves deposition efficiency, bonding strength, and hardness. In HA coatings, particles fragment into submicron grains and embed into the substrate through mechanical interlocking (MI), with shockwave-induced bonding strengthening subsequent layers. For Cu-Zn coatings, bonding occurs through MI and adiabatic shear instability (ASI). In HA-Cu-Zn coatings, high-velocity HA particles and Zn particles enhance bonding further through in-situ tamping.

Study of Am electrodeposition from AmCl3-LiCl-KCl Molten Salt

In this work, the electrodeposition reaction of Am in AmCl3-LiCl-KCl molten salt was studied using voltammetry and chronoamperometry. Electrodeposition of Am was shown to proceed via a two − step reaction scheme, involving the one-electron transfer reduction of Am3+ to Am2+, followed by the two-electron transfer reduction of intermediate Am2+ to Am0. A low Coulombic efficiency of Am deposition was measured despite the Am deposition occurring within the thermodynamic stability window of the supporting LiCl-KCl electrolyte. We hypothesize that the low efficiency is due to out-diffusion of the intermediate Am2+ species away from the electrode surface. Experimental observations provide evidence of a kinetically − limited electrodeposition reaction, which allows for the loss of intermediate Am2+ via diffusion leading to Am deposition inefficiency.

A modified separator based on ternary mixed-oxide for stable lithium metal batteries

Li metal batteries (LMBs) are among the most promising options for next-generation secondary batteries under the rapidly growing demand for high-energy–density electrochemical energy storage. However, the implementation of LMBs are hindered by major obstacles such as dentritic Li deposition and low cycling Coulombic efficiency. A practical functional separator is developed in this study, which consists of a Lewis acidic mixed oxide of ZrO2-SiO2-Al2O3 as a functional coating with anion anchoring ability to modulate ion transport in the vicinity of the Li metal anode, delivering a high Li+ transference number of 0.88 in carbonate electrolytes that suppresses dendrite formation. The strong Lewis acid sites in ZrO2-SiO2-Al2O3 originate from coordinatively unsaturated Zr4+ ions, which immobilize anions and reduce their decomposition rate. This significantly improves the chemical stability of the electrolyte and induces a more stable solid electrolyte interphase layer. The modified separator enables an anode-free cell containing a high-loading LiNi0.8Co0.1Mn0.1O2 cathode to present stable charge and discharge cycling for 150 cycles at 0.5C. By effectively suppressing Li dendrite growth and supporting the long-term operation of anode-free LMBs, this study offers a novel approach to rationally design mixed oxides with high Lewis acidity for functional separators.

Microstructure and properties of plasma sprayed NbC-Al2O3 composite coatings

Niobium carbide has received widespread attention due to its high melting point, high strength, high chemical stability and high wear resistance, but the current preparation of niobium carbide coatings using plasma spraying technology suffers from low deposition efficiency, poor fusibility of the composite powders, high porosity, and high defects in the coating microstructure. Therefore, the microstructure and properties of NbC-Al2O3 composite coatings prepared by plasma spraying NbC-Al2O3-SiC composite powder and reactive plasma spraying Nb2O5-SiC-Al composite powder were comparatively investigated in this paper. The reaction mechanism of Nb2O5-SiC-Al composite powder during plasma spraying as well as the mechanism of the formation of coatings were analyzed in detail. The results showed that compared with the ex-situ NbC-Al2O3-SiC coating fabricated by plasma spraying, the in-situ Nb2O5-SiC-Al composite coating prepared by reactive plasma spraying had an obvious layer structure, low porosity (5.8%), high hardness (1141 HV0.1), high toughness (22.94 J/m2), and good scratch resistance properties.

Improvement of gradient microstructure and properties of wire-arc directed energy deposition titanium alloy via laser shock peening

Wire-arc directed energy deposition (WADED) technology has been widely used in the remanufacturing of titanium alloy structural components benefited from with the advantages such as high deposition efficiency and low cost. However, due to the coarse and anisotropic microstructure, the complex internal stresses and processing-induced rough surface significantly reduce fatigue performance and reliability of the remanufactured structural components. In this work, surface modification of titanium alloy WADED repair component was carried out via laser shock peening (LSP), and its gradient structure, microhardness, residual stress and fatigue performance and enhancement mechanism were systematically investigated. Results indicated that the different microstructure of each region led to different responses under the action of LSP, which was related to the change of dislocation density. LSP induced crystal defects such as high-density dislocations, twins and stacking faults on the surface. A variety of crystal defects gradually decreased with the depth from the strengthened surface, formed a gradient microstructure and significantly affected the microhardness and residual stress of the repaired components. The surface hardness and compressive residual stress of the repaired components were greatly increased after LSP and the hardened layer and compressive residual stress depth affected layer were 600 μm and 800 μm, respectively. The average fatigue life of the additive repair component increased by 197 % under the synergistic effect of compressive residual stress and gradient microstructure.

Characterization of pediatric extrathoracic aerosol deposition with air-jet dry powder inhalers

The use of air-jet dry powder inhalers (DPIs) offers a number of advantages for the administration of pharmaceutical aerosols, including the ability to achieve highly efficient and potentially targeted aerosol delivery to the lungs of children using the oral or trans-nasal routes of administration. To better plan targeted lung delivery of pharmaceutical aerosols with these inhalers, more information is needed on the extrathoracic (ET) depositional loss in pediatric subjects when using relatively small (e.g., 0.5–2 μm) particles and including oral or nasal device interfaces. The objective of this study was to implement validated computational fluid dynamics (CFD) models to characterize ET depositional loss during mouth-throat (MT) and nose-throat (NT) aerosol administration to pediatric subjects (2–10 years old) using an air-jet DPI platform across a range of initial small-particle aerosol sizes (0.41–13.65 μm) and inhalation flow rates (8–20 L/min).A new CFD model focused on small-particle aerosol depositional loss in existing pediatric airway models was developed and validated with existing in vitro data. The validated CFD model was then used to characterize depositional loss in the MT and NT regions of children using particle sizes, flow rates and interfaces consistent with air-jet DPIs.Successful validation of the CFD model for small-particle aerosol deposition was achieved through enhanced resolution of the near-wall transport conditions. Existing non-dimensional parameters were used to produce high quality single-curve deposition efficiency correlations with r2 values in the range of 0.95–0.97. A new method for predicting realistic polydisperse aerosol deposition using the developed correlations and an equivalent monodisperse particle diameter was also introduced. In conclusion, the newly developed correlations will be useful in planning the lung delivery of next-generation inhaled medications, where achieving both low ET loss and targeted airway deposition, perhaps with excipient enhanced growth technology, are critical factors.

Optimizing Cold Spray Parameters for High Entropy Alloy Coatings Using Taguchi and Box–Behnken Design Approaches for Mechanically Alloyed Powder

AbstractThe present study focused on optimizing the cold spray (CS) process parameters for depositing Fe20Cr20Mn20Ni20Co20 (Cantor alloy) coatings using mechanically alloyed (MA) powder. A two-step design of experiments approach was employed, beginning with the initial screening of input variables using the L8 Taguchi method, followed by the refinement of process parameters through the Box–Behnken design of experiments. Key performance indicators included deposition efficiency (DE), coating thickness per pass, and microstructural parameters including porosity, cracks, and interfacial defects/delamination. The study identified process gas temperature as the primary factor influencing both DE and thickness per pass. Higher gas temperature and pressure, combined with increased scanning speed, resulted in higher DE. The DE of the MA Cantor alloy powder peaked at around 14-15%, with a deposit density greater than 99% achieved at the highest process gas temperature and pressure (1000 °C and 60 bar, respectively). The average hardness of the optimal CS coating deposited using MA powder was found to be 679 ± 17 HV0.1, which is approximately 90% greater than the average hardness reported for CS coatings deposited using atomized powder.

Synergistically achieving particulate matter reduction and production performance optimization for zinc electrolysis by ultrasonication coupling anode-coated MnO2

Abating particulate matter (PM) from electrolysis processes is significant because this PM poses occupational threats to workers and has a negative impact on air quality. However, it remains a challenge to synergize the reduction of PM production and the improvement of electrolysis performance. This study developed a green method, termed as the coupling of ultrasonication and pre-coating MnO2 anode treatment (UMT). The effects on PM generation rate and electrolysis performance indicators were estimated using the bench-scale zinc electrolysis device, and the synergistic mechanism of UMT was expanded from the perspective of electrochemical reactions and bubble characteristics using analysis of reaction products, camera technique, and PM generation prediction models. The results showed UMT not only overcame the degradation of deposited zinc quality caused by the ultrasonication treatment but also solved the increased PM generation by the pre-coating MnO2 film treatment. The UMT simultaneously reduced PM (33.9 %-57.5 %), decreased zinc impurity content by (11.2 %-54.3 %), improved current efficiency of zinc deposition (0.19 %-1.71 %), and conserved electrolysis energy (0.27 %-1.01 %). The optimal performance of UMT occurred at 80 kHz. The UMT suppressed the gas evolution reactions and prematurely bursting bubbles, in favor of reducing the number and size of bubbles, to reduce PM generation. Meanwhile, the UMT improved the electrolysis performance by inhibiting the corrosion of lead-based anodes, promoting the mass transfer rate of Zn2+, providing more active surfaces, and decreasing the overpotential of reactions. The findings may provide references for the green development of the metal electrolysis industry.

Comparison of off-target pesticide drift in paddy fields from unmanned aerial vehicle spraying using cellulose deposition sampler

Off-target pesticide drift in paddy fields following unmanned aerial vehicle (UAV) spraying was evaluated using cellulose deposition samplers (CDSs). An analytical method for quantifying ferimzone Z and E isomers deposited on CDSs was developed using LC-MS/MS. The suitability of the CDS method was confirmed by comparing deposition patterns on CDSs with residue levels in rice plant samples. To assess pesticide deposition in paddy fields, CDSs were strategically placed at varying distances from target areas, followed by UAV spraying. The fungicide agrochemicals were applied with and without adjuvants, and wind direction affected the drift trajectory for all treatment groups. Adjuvants, particularly soy lecithin as the major component, significantly enhanced pesticide deposition within the spray pathway while reducing drift rates relatively by 47.9–68.0 %. Higher wind speeds were found to exacerbate drift, but adjuvant-treated sprays showed less variability in deposition patterns under these conditions. Pesticide residues in harvested brown rice were found to be below the maximum residue limits (MRLs), ensuring safety for consumption. These findings highlight the importance of selecting appropriate adjuvants in UAV-based pesticide applications to optimize deposition efficiency and minimize environmental contamination.

Sedimentation rate changes across the Chinese Loess Plateau from luminescence dating of Malan loess in the Sanmen Gorge

Abstract The Chinese Loess Plateau (CLP), recognized as the world's largest loess plateau, has been a subject of ongoing debate regarding the continuity of its sedimentary loess sequence due to its intricate depositional environment. In this study, we conducted dating on a 9.8-m-long Malan loess core obtained from the Sanmen Gorge in the southern CLP using optically stimulated luminescence (OSL). The OSL dates indicate loess deposition between 52.4 and 11.3 ka, with no apparent hiatus on a millennial scale, and a sedimentation rate (SR) exhibiting six distinct episodes. Additionally, a comprehensive review of 613 OSL ages from 18 sections at 14 sites across the CLP was conducted. The results reveal loess deposition at most sites shows no apparent hiatus on a millennial scale over the past 60 ka, except for two specific locations. High SR episodes during Marine Isotope Stage (MIS) 3 across the CLP were attributed to heightened dust emissions from the source region and an enhanced dust deposition efficiency, while MIS 2 deposits were influenced by an intensified East Asian winter monsoon. Low SR episodes during MIS 1 at most sites were likely associated with reduced atmospheric transportation and pedogenesis. Spatially heterogeneous SR variations across the CLP might be influenced by local depositional environments.

Copper‐graphene coatings for improving thermal shielding of CFRPs through electrodeposition techniques

AbstractToday, carbon fiber reinforced plastics (CFRPs) are materials of interest several industrial sectors because of their mechanical properties and low weight. However, applications in high‐temperature areas are limited because of thermal degradation. Thus, thin coatings acting as thermal shielding and ensuring the upkeep of CFRP structural stiffness are of high interest. This work presents an innovative approach to produce copper/graphene bilayer coatings through electrodeposition and electrophoretic deposition; it consists of laser pre‐treatment of the composite surface to remove the matrix layer exposing the carbon fibers, enabling the subsequent deposition. Bi‐layer graphene/copper coatings exhibit an enhancement in copper electrodeposition efficiency of more than 59% resulting in a 97% stiffness improvement compared to the single layer copper electroplating. All the obtained coatings were able to act as a thermal shield of the CFRPs, reducing the maximum temperature of the composite by more than 60%. In particular, due to the synergistic effect of copper and graphene, the GNPs‐Cu coating achieved the highest maximum temperature reduction (81%). Cross‐sectional analysis indicates severe delamination in uncoated CFRPs, whereas double‐layer coatings maintain structural integrity and prevent delamination even under high‐energy exposure. In addition, the coated composites exhibit a higher electrical conductivity compared to the laser cleaned CFRP, with the GNPs‐Cu coating that obtained a 90% enhancement because of the outstanding electrical properties of copper and graphene.Highlights The laser cleaning pretreatment allows the electrodepositions on CFRPs. The GNP‐Cu scenario achieves the highest deposition efficiency. A 97% stiffness improvement was achieved by GNPs‐Cu scenario. GNPs‐Cu coatings exhibit the utmost reduction in resistivity (98%). The GNPs‐Cu coating achieves the highest thermal shielding performance (81%).

447 Ex-food4feed: Keeping nutrients in the food chain - Sponsored by EAAP

Abstract The growing world population and rising income in developing countries create more demand for animal products. However, natural resources such as land, water, and nutrients are not boundless. As a consequence, competition of resources in food and feed production is an issue to be confronted with. One promising solution is relocating food losses into animal feeding, propelling the course of sustainability and circular economy in the livestock sector. Given this scenario, former food products (FFPs) represent great opportunities. Instead of ending up in landfill or compost, a better destination for FFPs is to be used as feedstuffs to replace traditional ingredients. FFPs are foodstuffs not accepted by the human market but have several advantages enabling them to enter swine feeding programs. FFPs are mainly composed of processed and ready-to-eat food products such as snacks and bakery goods. Thanks to industrial processing and their product type nature, FFPs are rich in easily digestible starch, simple sugars, fat, and energy contents comparable with cereal grains. Based on their nutritional features, these materials are extremely rich in carbohydrates, free sugars and, depending on their origin, also in fats. In addition, FFPs are often characterized by a high degree of processing including technological and heat treatments which can affect not only the availability of nutrients and the kinetics of digestion, but also gastro-intestinal health and animal response. On fresh matter basis, FFPs can substitute conventional feed ingredients up to 30 % in the diets of pigs. Starting from post-weaning piglets, FFP-based diet is able to maintain piglet growth without substantial effects on hindgut microbiota. In growing-finishing pigs, FFP-based diets at a 30 % inclusion level support growth performance of pigs without altering their nutrient and energy deposition efficiency, live body and carcass composition, and general meat quality traits. When considering liver proteome and plasma peptidome of pigs fed such diets, minor modulation occurs. To sum up, while maintaining the performance and wellbeing of pigs, the use of FFPs up to 30 % to replace classic feedstuffs represents a great potential in: i) mitigating food-feed competition, ii) re-distributing valuable food losses to livestock sector to produce animal protein, and iii) reducing environmental footprints resulting from animal production. All these aspects point out important concepts under the principles of circular economy and resilience enhancement in livestock farming, namely, making the most of resources to build a regenerative food system.