Specific Strength Research Articles

Determination of Composition and Density of Sandwich Composites Produced by Vacuum Lamination

Purpose: This study aims to characterize the composition and density of bulkheads manufactured by vacuum lamination. Theoretical Framework: Sandwich composites are widely used due to their high specific strength, a critical factor in reducing energy consumption associated with weight, especially when manufactured through vacuum lamination. However, the final composition and density of these materials are important factors for decision-making in the project, but they are often not known beforehand. Method: Characterization was carried out on five samples taken from different regions of the laminated plates. The composition was determined by varying the area density, and the final composite density was obtained based on the observed composition and the density of the components. Results and conclusion: The results indicated a density of 0.21 g/cm³ for the laminated material. The analysis allowed determining the mass and volumetric fractions of the components, demonstrating the consistency of the manufacturing parameters and their adequacy to the project's requirements. Research Implications: This study contributes to improving the vacuum lamination process by providing a methodology for characterizing the density of sandwich composites, which can be applied in various projects, as well as providing reference values. Originality/Value: The research offers an innovative approach by exploring the variation of area density to characterize the composition of composites, contributing to the optimization of the sandwich composite manufacturing process, such as the vessel “Gigante Vermelho” used in the Desafio Solar Brasil 2022.

Marketing Strategy for Mitraguna Online Financing Products in Increasing the Number of Customers

This study aims to determine potential marketing strategies to increase the number of customers in the online mitraguna financing product of Bank Syariah Indonesia, Kisaran sub-branch office. This research uses qualitative research methodology. In qualitative research, the findings are analyzed and then reported by the researcher. In this study, two different types of data were used, namely primary and secondary. Interviews were used to obtain primary data, while publications from relevant financial institutions as well as relevant scientific literature were used to collect secondary data. The results of the data analysis resulted in the largest threat weight of 0.092538, the largest opportunity weight of 0.571429, the highest weakness weight of 0.210526, and the highest strength weight of 0.421053. The average overall score of the Internal Factor Evaluation matrix is 2.736842, but the average score of the External Factor Evaluation matrix is 2.952381. The results of this study indicate that the marketing strategy that needs to be implemented lies in quadrant V, namely the strategy of maintaining and maintaining by obtaining 5 alternative strategies that are expected to contribute to the Bank Syariah Indonesia Kisaran sub-branch office to increase the number of online mitraguna financing customers.

Programmable adhesion through triangular and hierarchical cuts in metamaterial adhesives.

Metamaterial design approaches, which integrate structural elements into material systems, enable the control of uncommon behaviours by decoupling local and global properties. Leveraging this conceptual framework, metamaterial adhesives incorporate nonlinear cut architectures into adhesive films to achieve unique combinations of adhesion capacity, release, and spatial tunability by controlling how cracks propagate forward and in reverse directions during separation. Here, metamaterial adhesive designs are explored with triangular cut features while integrating hierarchical and secondary cut patterns among primary nonlinear cuts. Both cut geometry and secondary cut features tune adhesive force capacity and energy of separation. Importantly, the size and spacing of cut features must be designed around a critical length scale. When secondary cut features are greater than a critical length, cracks can be steered in multiple directions, going both forward and backwards within a primary attachment element. This control over crack dynamics enhances the work of separation by a factor of 1.5, while maintaining the peel force relative to a primary cut. If hierarchical cut features are too small or too compliant, they interact and do not distinctly modify crack behaviour. This work highlights the importance of adhesive length scales and stiffness for crack control and attachment characteristics in adhesive films.This article is part of the theme issue 'Origami/Kirigami-inspired structures: from fundamentals to applications'.

Enlarged Curvature, Torsion and Torque in Helical Conformations and the Stability and Growth of α-Peptide under the Isochoric and Isobaric Conditions: Variatonal Optimization

The torsional deformation behavior of an elastic bar with a circular cross-section was investigated by applying invariant dyadic analysis, where the small finite displacement functions advocated by Saint-Venant (1855) were fully employed. It was found that the previously overlooked circumferential shear force field generated by pure torsion on the side walls of a bar produces an unusual torque term induced by the skew-symmetric part of the deformation tensor and exhibits quadratic length dependence along the z-axis of the bar. The adaptation of this torque term for a helical conformation of α-peptides creates moments acting on the circular cross-sections and is directed along the surface normal of circular cross-sections, which coincides with the tangent vector of the helix. The projection of this torque along the z-axis of the helix varies quadratically with the azimuthal angle. The radial component of the unusual torque, which also lies along the principal normal vector of the helix, starts to perform a precession motion by tracking a spiral orbit around the z-axis, whereas its apex angle decreases asymptotically with the azimuthal angle and finally reaches a finite value depending on the height of the helix along the z-axis. The ordinary torque terms, which are also deduced from the self- and anti-self-conjugate parts of the deformation tensor, have magnitudes half that of the full torque term reported in the literature. The present results were applied to the helical conformation of α-peptides designated by {3.611} to show that the mechanical stability of strained open-ended helical conformations can be successfully achieved by spontaneous readjustments of the surface and bulk Helmholtz free energies under isothermal isochoric conditions. It has been demonstrated that the main contribution to the mechanical stability of α-peptide 3.611 cannot come alone from the electrostatic dipole-dipole interaction potential of the anti-align excess dipole pairs but also from the surface Helmholtz free energy, which is characterized by a binding free energy of -15.5 eV/molecule (-32.56 Kcal/mole) for an alpha-peptide composed of 11 amino acid residues with a critical arc length of approximately 10 nm, assuming that the shear modulus is G = 1GPa and the surface Helmholtz specific free energy density is fs = 800 erg/cm2. This result was in excellent agreement with the experimental observations of the AH-1 conformation of (Glu)n Cys at pH 8. The present theory indicates that only two excess permanent anti-align dipole pairs for one α-Helical peptide molecule is requirement to stabilize the whole secondary structure of the protein that is exposed to heavy torsional deformation during the folding processes which amounts to 7.75 eV/molecule stored electrostatic energy compared to the interfacial Helmholtz free energy of -23.25 eV/molecule, which is exposed to hydrophobic environments.

Experimental Investigation on Novel Lattice Structure Parts of IN718 Made by Laser Powder Bed Fusion for Enhanced Specific Flexural Strength

Experimental Investigation on Novel Lattice Structure Parts of IN718 Made by Laser Powder Bed Fusion for Enhanced Specific Flexural Strength

Individualized Assessment and Treatment Program (IATP) for alcohol use disorder: Comparison with conventional cognitive-behavioral treatment and examination of coping skills as a mediator of treatment.

This study tested a highly individualized cognitive-behavioral coping skills treatment for alcohol use disorder (AUD). Recent studies have indicated that coping skills training programs are not always effective. A possible explanation is that the training provided in these programs may not address the specific needs of the patient. The Individualized Assessment and Treatment Program (IATP) was intended to provide a highly individualized approach to the training of skills most relevant for each individual. Men and women with AUD (N = 173) were randomly assigned to one of three, manualized, 12-session treatments: IATP, a conventional (Packaged) cognitive-behavioral program (PCBT), or a Case Management control condition (CaseM). An experience sampling (ES) procedure was employed prior to, and during, treatment to record alcohol use and coping behaviors in all patients. In IATP, this information was used by therapists to plan treatment that would address the specific strengths and weaknesses of each patient in alcohol-use situations. ES data were collected at multiple time points and patients were followed every 3 months out to 21 months posttreatment. Multilevel model analyses indicated that IATP yielded better drinking outcomes than the CaseM or PCBT conditions. Mediation analyses indicated that the effects of IATP versus the other treatments on outcomes were accounted for at least partly by changes in active coping with high-risk situations. Due to the limited diversity of the sample, generalizability of the results may be limited. Results are discussed in terms of the importance of tailoring treatment for the individual patient. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Fracture characteristics and microscopic mechanism of slag-based marine geopolymer mortar prepared with seawater and sea-sand

This study utilized seawater, sea sand, and ternary solid waste to produce marine geopolymer mortar (MGM). 23 groups of MGM samples with varying alkali content and basalt fiber (BF) and polypropylene fiber (PPF) volume fractions, as well as marine cement mortar (MCM), were tested for fracture characteristics. Three initial crack length ratios (a0/h) (0.2, 0.3, and 0.4) were designed. The analysis included load-crack mouth opening displacement (P-CMOD) curves for all specimens, focusing on critical crack length (ac), critical crack tip opening displacement (CTODc), fracture toughness (KSIC), fracture energy (GF), and facture brittleness index (FBI). Results indicated that increasing alkali content enhanced strength and elastic modulus, peak fracture load, critical crack extension length (Δac), and CTODc, while decreasing final CMOD. This was attributed to the increased alkali content, which enhanced the mortar’s density. However, excessive alkali content also led to increased shrinkage damage within the matrix, making it prone to stress concentrations and resulting in brittle failure. Based on the research, it is recommended that the alkali content be controlled within the range of 4–5 %. Hybrid fibers showed superior overall toughness enhancement, increasing KSIC, GF, and FBI by 54.3 %, 95.6 %, and 427.4 %, respectively. This improvement was due to the synergistic effect of BF and PPF, which increased the specimen’s elastic modulus, reduced crack propagation speed, and sustained load-bearing capacity during the later stages of crack development. The fracture toughness of conventional geopolymer mortar was positively correlated with the Ca/Si ratio and was lower than that of MGM. In contrast, MGM’s Ca/Si ratio showed an inverse correlation with KSIC, indicating that phase assemblage governs the fracture resistance of MGM. This is because Cl- in seawater intensified geopolymerization reactions. Interwoven gel structures in MGM, with surface depositions like magnesium aluminosilicate hydrate (M-A-S-H), magnesium silicate hydrate (M-S-H), and silica gel, filled pores, and improved homogeneity, resulting in its superior fracture toughness over conventional geopolymer mortar.

Development of a 7000 series aluminium alloy suitable for laser-based Additive Manufacturing

High strength aluminium alloys are of significant interest for laser-based Additive Manufacturing as they can provide a high specific strength but have limited assembly possibilities due to poor weldability and the presence of large intermetallic particles challenging the conventional manufacturing route. Increasing the geometrical freedom by enabling their use with laser-based Additive Manufacturing would create new possibilities. This study investigates the possibilities of using an aluminium 7000 series alloy with Laser Powder Bed Fusion (L-PBF) and secondly for comparison with Direct Energy Deposition (DED). The chemical composition targets 5.1–6.1 wt% Zn and 2.1–3.9 wt% Mg. The level of Zn and Mg in the powder was increased to 10 wt% Zn and 3 wt% Mg to compensate for the expected evaporation during the laser-based AM process and guarantee a sufficient Zn and Mg content for precipitation strengthening. Solidification cracking in the initial alloy composition was resolved by the addition of 1 wt% Zr and 1 wt% V. For L-PBF, a study of the impact of the laser spot size showed a larger spot size is beneficial to improve the process stability. A study of the capability of preheating and of slowing down the process showed both further improve the process stability as well which is required to manufacture successfully larger parts to characterise the quasi-static tensile properties. For optimal process parameters for a fast process, meaning a scan speed of 700 mm/s, a yield stress of 425 ± 7 MPa and an ultimate tensile strength of 442 ± 5 MPa was obtained after a homogenisation and ageing heat treatment. In the as built state, the strength was significantly lower. For optimal process parameters for a slow process, meaning a scan speed of 250 mm/s, a yield stress of 398 ± 11 MPa and an ultimate tensile strength of 440 ± 16 MPa were obtained in as built state. For DED the mechanical properties of the alloy showed to be significantly dependent on process parameters. An excessive energy input results in more Zn and Mg evaporation and decreased cooling rates. Such parameters also impact the process stability of DED throughout the build cycle. Limiting the energy input resulted in dense samples and stable build cycles which after a heat treatment to peak ageing reached a yield stress of around 400 MPa and an ultimate tensile stress of around 440 MPa in the X- and Z-direction.

Scaling analysis of electrodeposited copper and the influence of a modified polysaccharide on surface roughness

The influence of a commercially available modified polysaccharide (HydroStar®, Chemstar Chemical Products) on the roughness of short-term and small-scale copper electrodeposits was investigated using Atomic Force Microscopy (AFM), linear scan profilometry and scaling analysis. Copper was deposited on a 316L stainless steel cathode at 40 °C and 300 A m−2 from an electrolyte containing 40 g L−1 Cu2+, 170 g L−1 H2SO4, 1.5 g L−1 Fe3+, 15 mg L−1 Cl− and either 0, 10, 50 or 100 mg L−1 of HydroStar. Copper deposits produced between 15 and 25 min were imaged using AFM and 2D linear scan profilometry was used to gather surface features of copper samples produced in the range of 120 and 240 min. Scaling analysis was applied to quantify the surface characteristics of limiting roughness (δ) and critical length (LC) from which δ/LC was computed and related to the aspect ratio of surface features. All copper deposits showed a general rise in δ and LC with deposition time but the growth rates decreased when HydroStar was included in the electrolyte indicating that the additive lowers the vertical height of surface features as well as their widths. Furthermore, copper deposits were more consistently produced in the presence of HydroStar and, for a given value of limiting roughness, had surface features with wider base than those created in the absence of the additive. The results show that the modified polysaccharide acts to create smooth copper deposits by generating surface features with lower aspect ratios.

Recycling phosphogypsum to produce artificial lightweight aggregates via stirring and pelleting all-in-one technique: Technical assessment and performance optimization

Currently, production of artificial lightweight aggregates (ALAs) is becoming one of the most promising approaches for solid wastes recycling via pelletization technique. In this study, an innovative stirring and pelleting all-in-one technique (S-pelleting) was employed to prepare the ALAs by using phosphogypsum (PG). The effects of different pelleting techniques on properties of the ALAs were investigated. Furthermore, the NaHCO3, Al2(SO4)3+CaCO3 (Al-Ca) and foamed particles (FP) were introduced as foaming agents to optimize the performance of the ALAs. The specific strength was used as the main assessment index for performance of the aggregates. The results indicated that the specific strength of the aggregates was improved to 10.96 MPa⋅cm3/g by S-pelleting, which was 60.7 % and 35.6 % higher than that of one-step pelleting or double-step pelleting technique. Compared to NaHCO3, the Al-Ca was more conducive to the specific strength development of the aggregates, and the FP addition could further improve the specific strength of the ALAs. When the concentration of Al-Ca was 7% and the mass fraction of FP was 10%, the ALAs with high specific strength of 9.6 MPa⋅cm3/g were obtained in this study. Moreover, the mineral composition, microstructure and pore structure of the ALAs were analyzed and the results reveled that the Al-Ca could promote to form more ettringite and reduce the proportion of harmful pores in the aggregates, which was responsible for the improvement in specific strength. The FP acted as a lightweight skeleton supported inside the aggregates and the well bonded ITZ between FP and the matrix could further improve the specific strength of the ALAs. Finally, the durability and environmental impact of the ALAs were evaluated acceptable. Overall, this study not only provided a green approach for PG recycling, but also presented a new technical scheme for more efficient production of ALAs.

Adaptive feature alignment for adversarial training

Recent studies reveal that Convolutional Neural Networks (CNNs) are typically vulnerable to adversarial attacks. Many adversarial defense methods have been proposed to improve the robustness against adversarial samples. Moreover, these methods can only defend adversarial samples of a specific strength, reducing their flexibility against attacks of varying strengths. Moreover, these methods often enhance adversarial robustness at the expense of accuracy on clean samples. In this paper, we first observed that features of adversarial images change monotonically and smoothly w.r.t the rising of attacking strength. This intriguing observation suggests that features of adversarial images with various attacking strengths can be approximated by interpolating between the features of adversarial images with the strongest and weakest attacking strengths. Due to the monotonicity property, the interpolation weight can be easily learned by a neural network. Based on the observation, we proposed the adaptive feature alignment (AFA) that automatically align features to defense adversarial attacks of various attacking strengths. During training, our method learns the statistical information of adversarial samples with various attacking strengths using a dual batchnorm architecture. In this architecture, each batchnorm process handles samples of a specific attacking strength. During inference, our method automatically adjusts to varying attacking strengths by linearly interpolating the dual-BN features. Unlike previous methods that need to either retrain the model or manually tune hyper-parameters for a new attacking strength, our method can deal with arbitrary attacking strengths with a single model without introducing any hyper-parameter. Additionally, our method improves the model robustness against adversarial samples without incurring much loss of accuracy on clean images. Experiments on CIFAR-10, SVHN and tiny-ImageNet datasets demonstrate that our method outperforms the state-of-the-art under various attacking strengths and even improve accuracy on clean samples. Code will be made open available upon acceptance.

Preparation, pore structure and properties of uniformly porous glass-ceramics sintered from granite powder using SiC@SiO2 foaming agent

Granite sludge produced during the processing of granite blocks should be efficiently recycled for environmental protection and as a sustainable resource. In this work, porous glass-ceramics were prepared by stepwise sintering of granite powder using core-shell SiC@SiO2 foaming agent. The SiC and SiC@SiO2 foaming agents were compared in terms of the sintering and foaming behaviors of the powder compacts by thermal expansion, thermogravimetry and mass spectroscopy. The foaming agent and foaming temperature were investigated to study their effects on the pore structure and properties of the porous glass-ceramics. The SiO2 shells of the SiC@SiO2 particles inhibited the oxidation of the SiC cores and the release of CO2 at the early stage of the sintering process, thus preventing pore coalescence and increasing the densification and specific strength of the sintered glass-ceramics. As the foaming temperature increased, the porous glass-ceramics exhibited a linear relationship between pore size and foaming temperature, and the specific strength first increased and then decreased due to pore coalescence and reduced crystallinity. Furthermore, the linear relationship between thermal conductivity and porosity indicates a closed pore structure, as demonstrated by computed tomography. At a foaming temperature of 1220 °C, the porous glass-ceramic has a porosity of 50.1 %, a specific strength of 16.6 kN⋅m/kg and a thermal conductivity of 0.747 W/(m⋅K). Numerical simulation confirms that lightweight glazed glass-ceramics have potential applications in energy-efficient building tiles.

A critical assessment of geological weighing lysimeters: Part 2—Modelling field scale soil moisture storage and hydrological fluxes

AbstractLand surface models (LSMs) are used to simulate the terrestrial component of water, energy, and biogeochemical cycles. These simulations are useful for water resources management, drought and flood prediction, and numerical climate/weather prediction. However, the usefulness of LSMs are dependent by their ability to reproduce states and fluxes realistically. Accurate measurements of water storage are useful to calibrate and validate LSMs outputs. Geological weighing lysimeters (GWLs) are instruments that can provide field‐scale estimates of integrated total water storage within a soil profile. We use field estimates of total water storage and subsurface storage to critically evaluate two different land surface models: the Modélisation Environnementale communautaire—Surface Hydrology (MESH) which uses the Canadian Land Surface Scheme (CLASS), and the Structure for Unifying Multiple Modeling Alternatives: (SUMMA). These models have differences in how the processes and properties of the land surface are represented. We attempted to parameterize each model in an equivalent manner, to minimize model differences. Both models were able to reproduce observations of total water storage and subsurface storage reasonably well. However, there were inconsistencies in the simulated timing of snowmelt; depth of soil freezing; total evapotranspiration; partitioning of evaporation between soil evaporation and evaporation of intercepted water; and soil drainage. No one model emerged as better overall, though each model had specific strengths and weaknesses that we describe. Insights from this study can be used to improve model physics and performance.

Surgical Outcomes of Total Hip Arthroplasty with Paavilainen Osteotomy in Patients Who Have High Developmental Hip Dislocation: Mean 4.4 Year Follow-Up

BackgroundAlthough subtrochanteric osteotomy is a common procedure, the use of Paavilainen osteotomy combined with total hip arthroplasty (THA) for high developmental hip dislocation is less documented. This study assessed the efficacy and complications of this approach, with a particular focus on the risk factors for nonunion post-osteotomy. MethodsAll patients who had high dislocated hip dysplasia who underwent combined THA and Paavilainen osteotomy, were retrospectively reviewed with over one year of follow-up. A total of 44 patients (51 hips) were included, with an average follow-up period of 4.4 years (range, 1.97 to 6.94). Anatomical data of the hip joints were measured on pre- and postoperative radiographs. Demographic data, Trendelenburg sign, complications related to this procedure, Harris Hip Score (HHS), and EuroQoL-5-Dimension 5-Level (EQ-5D-5L) health questionnaire were collected from the medical chart. Binary logistic regression analysis was used to identify predictors for bone nonunion. ResultsOut of the 51 hips, eight displayed a positive Trendelenburg sign. Patients' HHS saw an improvement from 43.8 ± 11.8 preoperatively to 85.7 ± 11.1 at the latest follow-up (P < 0.001), accompanied by a substantial enhancement in the average EQ-5D-5L score from 0.38 ± 0.15 to 0.87 ± 0.13 (P < 0.001). Nonunion, as the most concerning complication, occurred in 12% (seven of 56) of osteotomy cases. The contact length between the osteotomy block and femoral cortex was a key risk factor for nonunion. The Receiver operating characteristic (ROC) analysis identified 2.15 centimeters (cm) as the critical bone contact length for healing. ConclusionsPaavilainen osteotomy combined with THA and subtrochanteric osteotomy proved effective and less complex than other techniques for high-dislocation hip dysplasia. A bone contact length between the greater trochanteric fragment and the femoral cortex of less than 2.15 cm is a risk factor for nonunion.

Acoustic Emission simulation: assessing the influence of AE source modeling and addressing the issue of dimensionality in the propagation medium

A thorough understanding of simulating Acoustic Emission (AE) requires the source modeling and propagation medium to be considered respectively. Crack initiation and propagation simulation as an AE source can be performed by the Successive Node Release (SNR) method and the Direct Node Release (DNR) method. Both are compared to show how the source model affects the AE signals. The SNR method is commonly used to simulate the crack initiation and propagation. It is necessary to consider the influence of the crack velocity profile on the crack initiation [1]. However, for the DNR method, all nodes are instantaneously released once the critical crack length is attained. Hence, it is not necessary to consider the velocity profile. Instead, it is sufficient to define the average crack velocity. However, the kinetic energy varies when employing different methods, leading to a variance in the source energy. We thus assess the suitable conditions to apply the DNR method to represent crack initiation and investigate the influence of the node release methods on the AE signals. Secondly, a comparative assessment of the Pencil-lead Break test on PMMA plates is conducted using both two-dimensional (2D) and three-dimensional (3D) finite element simulations. This analysis is valuable for understanding the deficiencies and constraints of the 2D simulation. However, there is a significant difference in the AE signals between 2D and 3D simulations, suggesting that the 2D simulation is unable to capture the AE information during wave propagation, in spite of its lower computational cost. Therefore, to obtain extensive and precise information from the PLB test, it is crucial to have an extensive understanding of the limits of the 2D simulation. This understanding should take into account factors such as the distance between the sensor and the source, as well as the descriptors chosen to characterize the AE.

Enhancing mechanical performance of Ti2ZrNbHfVAlx refractory high-entropy alloys through laves phase

Refractory high-entropy alloys (RHEAs) have attracted significant interest because of their exceptional mechanical characteristics. This study examines the mechanical characteristics, microstructure and strengthening mechanism of Ti2ZrNbHfVAlx alloys (x = 0, 0.2, 0.4, 0.6, 0.8, 1, and 1.2). The results demonstrate that the introduction of Al causes a transformation in the phase structure of the alloys, resulting in the BCC phase and the Laves phase, characterized by a distinctive dendritic microstructure. The compressive yield strength is positively correlated with the rising Al content, while also resulting in a noticeable decrease in ductility due to the presence of the Laves phase. One of the alloys, the compressive yield strength of Ti2ZrNbHfVAl1.2 RHEA is as high as 1789.94 MPa, the compressive strain is 10.60 %, and the specific yield strength (SYS) of 269.67 kPa m3 kg−1. Moreover, the Vickers hardness exhibits a rise from 317.29 to 533.73 HV. The high compressive yield strength mostly originates from solid solution and the second phase strengthening. The current investigation not only offers a resolution for attaining a harmonious combination of strength and ductility but also gives a valuable understanding of the advancement of RHEAs with exceptional mechanical characteristics.

Effects of pulsed magnetic field intensity on the freezing rate and heat loads reduction of harvested mango and tomato

PurposeFresh fruits and vegetables (FV) are crucial global food resources, but the presence of heat loads during harvest adversely impacts their shelf life. While freezing technology provides an effective means of removing heat loads, it is an energy-intensive process and may consequently prove too costly for practical business viability. The growing interest in utilizing magnetic field (MF) technology during the freezing of fresh FV enhances the freezing rate and rapidly removes the heat loads of products.Design/methodology/approachIn the present study, pulsed magnetic field (PMF) pretreatment employing specific field strengths (9 T, 14 T and 20 T) was examined as a preliminary step before freezing mango and tomato and compared to the conventional freezing method (untreated) at − 18 °C.FindingsPMF pretreatment prior to freezing demonstrated a noteworthy enhancement in freezing rate by around 10 and 12% when compared with the conventional (untreated) freezing, which exhibited freezing rates of −0.08 °C/min and −1.10 °C/min for mango and tomato, respectively. The PMF pretreatment (at 20 T) provided a higher freezing rate (at p = 0.05) than the conventional freezing method reduced heat loads amounting to 1.1 × 107 J/kg oC and 2.9 × 106 J/kg oC, significantly (at p = 0.05) from mango and tomato, respectively. These reductions in heat loads were approximately more than 5% of the calculated heat loads removed during conventional freezing.Research limitations/implicationsMango and tomato samples were only tested; the results may lack generalizability. Therefore, researchers are encouraged to test for other products for further studies.Practical implicationsThe paper includes implications for the development of a rapid freezing technique, the development of “pulsed magnetic field” and for eliminating the problem associated with conventional (slow) freezing.Originality/valueThe study holds significance for the production of postharvest freezing technology, providing insightful information on the PMF-assisted freezing of cellular foods.

Preparation and Characterization of Lightweight Carbon Foam Derived From Silicon‐Containing Arylacetylene Resin With Antioxidant Properties and Excellent Electromagnetic Interference Shielding Performance

ABSTRACTIn this study, carbon foam derived from silicon‐containing arylacetylene resin (CFPSA) was prepared by using silicon‐containing arylacetylene (PSA) resin as the carbon precursor and polyurethane (PU) foam as the organic sacrificial template. CFPSAs with diverse apparent densities were prepared through the simple impregnation of PU foam with PSA resin solutions of varying concentrations. Their structures, such as the pore morphology; chemical composition; thermal stability; compression properties, and electromagnetic interference (EMI) shielding effectiveness (SE), were characterized. The results indicate that with an increase in the PSA resin concentration, the skeleton of CFPSA becomes thicker, the pore size slightly increases, the apparent density increases, the compressive strength increases, and the EMI SE slightly reduces. CFPSA‐10's apparent density is 0.032 g/cm3, its 5% thermal weight loss temperature (Td5) in an air atmosphere is 642°C, its thermal conductivity is 38.1 mW/m K, its specific compression strength is 2.45 MPa/g cm3, and its specific EMI SE divided by thickness (SSE/t) is 2367 dB cm2/g. CFPSA exhibits lightweight and antioxidant properties, as well as excellent electromagnetic interference shielding performance, presenting great potential for application in aerospace and other fields.

Designing spongy-bone-like cellular materials: Matched topology and anisotropy

Bone is a natural material with properties such as high specific stiffness and strength. These exceptional mechanical properties are attributed to the meso-scale structure and elastic anisotropy of spongy bone. Replicating the topological traits and mechanical properties of spongy bone presents a novel opportunity to develop high-performance cellular materials. To achieve this, we propose an innovative framework for designing biomimetic cellular materials that match the trabecular structure and elastic anisotropy of spongy bone. This framework introduces a forward-flow design process that utilizes gradient-based feature tuning on a low-dimensional feature vector, transforming the complex inverse design problem into an efficient iterative process. A key innovation in our approach is the use of a pre-trained generative model, SliceGAN, to reconstruct 3D unit cells from 2D micro-CT images. This significantly reduces the cost and time associated with traditional layer-by-layer CT scans typically required for 3D training data. Numerical homogenization is then used to determine the effective elastic stiffness matrix, and a Fourier neural operator is trained to predict these matrices efficiently, greatly enhancing the computational efficiency of the design process. Using this framework, we successfully designed unit cells with topological traits and elastic anisotropy that closely approximate those of natural spongy bone. This opens new avenues for developing spongy-bone-mimetic cellular materials with exceptional mechanical properties. Moreover, the framework's versatility allows it to be extended to the design of other bio-inspired cellular materials.

Effect of the over-aging degree on high cycle fatigue properties of an ultra-high strength Al-Zn-Mg-Cu alloy

An ultra-high strength Al-Zn-Mg-Cu alloy with high Zn content was subjected to T6, T79, T76, T74 and T73 ageing treatments in order to investigate the effect of the over-aging degree on the high cycle fatigue (HCF) properties of the alloy. The microstructures and fatigue fracture morphologies were analyzed. The results showed that the fatigue strengths exhibited a non-linear trend of first increasing and then decreasing from the T6 to T73 aged samples. The T79 aged sample obtained the highest fatigue strength, was 247MPa. The Basquin equation was used to describe the changes in HCF properties. The physical meanings and causes of changes in the parameters of the fitted Basquin equation were rationalized by combining quantitative analysis of the microstructures and existing models. The combination of microstructural evolution and the trend of parameters in the fitted Basquin equation was ultimately employed to elucidate the underlying mechanism of the specific non-linear fatigue strength trend.