Homogenization Approach Research Articles

Development and characterization of inhaled nintedanib-loaded PLGA nanoparticles using scalable high-pressure homogenization technique

Presently, non-invasive targeted drug delivery to the lungs represents a routinely investigated approach to treat challenging disorders such as pulmonary fibrosis. Nintedanib (Nint) is an FDA-approved drug for treating idiopathic pulmonary fibrosis and certain interstitial lung diseases. Nint acts as a multiple tyrosine kinase inhibitor, demonstrating anti-neoplastic effects in non-small cell lung cancer. However, limitations of oral administration of Nint include low bioavailability and high dose requirement for adequate therapeutic efficacy, resulting in adverse effects like abdominal pain, sickness, diarrhea, and vomiting. In this project, Nint was reformulated into PLGA nanoparticles (Nint-NPs) for direct-lung administration to address these deficiencies and enhance its potential. In this project, Nint-NPs were designed utilizing a high-pressure homogenization (HPH) approach with excellent reproducibility and scale-up feasibility. Selected Nint-NP formulation revealed 43.3 ± 4.0 % of entrapment efficiency and 179.8 ± 3.1 nm of size. In-vitro release study showed an initial burst release of 36.0 ± 7.5 % within 30 min, followed by sustained release up to 71.0 ± 4.3 % by 96 h. Further, Nint-NPs were found to be stable after 1-month of storage in refrigerated and accelerated conditions. Interestingly, the results of lung deposition demonstrated ideal MMAD values less than 5 μm in all three nebulizer types tested (jet, breath-actuated jet, and vibrating mesh nebulizers), indicating Nint-NPs are appropriate for deep-lung delivery. In-vitro cellular uptake analysis exhibited higher internalization of NPs in alveolar epithelial cells and lung fibroblasts while avoiding macrophage uptake. Toxicity studies on normal lung cells indicated Nint-NPs were safe for use. Taken together, inhalation therapy of Nint-NPs offers a favorable alternative to oral capsules for treating respiratory diseases.

Overall elastic characterization of equivalent FE models for aluminum foams through computational homogenization approach and genetic algorithm optimization

Aluminum foams are gaining increasing interest because of their widespread set of functional attributes combined with highly specific structural properties and affordable manufacturing processes. The finite element analysis of foam materials is typically performed with complex and time-consuming 3D models. Here, a beam FE model strategy is utilized to obtain a precise and time-saving simulation instrument for open-cell aluminum foams. The beam FE modeling is based on the Kelvin cell as a fundamental unit and provides a simplified geometrical description of the intersection node between ligaments whose elastic properties need to be adjusted through a calibration procedure. The beam FE model elastic properties are measured through a homogenization procedure that evaluates the elastic constants of an equivalent material. The issue of model calibration is formulated as an optimization problem exploiting the NSGA-II genetic algorithm. This procedure allows obtaining the full elastic calibration of the beam FE model, reproducing the orthotropic elastic behavior of the aluminum foams with reduced computational efforts.

Flood Attenuation Potential of Italian Dams: Sensitivity on Geomorphic and Climatological Factors

In this work the attenuation potential of flood peaks of 265 large reservoirs all over Italy is analysed, considering a flood management that excludes gates opening and then configures strictly unsupervised attenuation effects. Key factors of dams and related basins are considered to develop a ranking method that can emphasize the interplay between dam geometry and the hydrological processes acting in the upstream watershed. To maintain a homogeneous approach in such a wide geographic area, the attenuation index is computed applying the numerical solution of the differential equation of lakes and only two different standardized hydrograph shapes have been used. An index design flood from the rational method is used as the incoming peak value for each dam, enhancing the use of the results of a recent analysis of all Italian rainfall extremes. Even with a very simple approach, twenty-four different design incoming floods are derived, by varying the shape of the incoming hydrograph and the parameters of the rational method. Exploring the ranking results in all the alternatives, the attenuation potential obtained for all dams demonstrates to be strongly sensitive to the assumptions on the time of concentration and to some rainfall features. On the other hand, the hydrograph shape seems to exert much less influence on the ranking outcome. Results obtained can be useful to studies of wide-area flood frequency analyses, as we highlighted the sensitivity of the rank of attenuation efficiency to hydrologic parameters widely used in the assessment of the design flood peaks in ungauged basins.

Evaluation of the damping characteristics of a hybrid piezo-shunt nanocomposite using a two-step homogenization approach

Composite materials containing piezoelectric particles have attracted remarkable attention because of their distinctive electromechanical conversion characteristics. These supreme properties lead to their applications in various fields, such as vibration damping of structures. The damping parameter of dynamic systems is crucial, especially when they undergo resonance phenomena. Multi-phase polymer matrix composites consisting of piezoelectric particles are innovative material systems that have been recently introduced to convert the mechanical vibrations into electrical energy, and subsequently dissipate into heat through an internal electrical circuit. The present study aims to analytically investigate the viscoelastic characteristics of a shunted three-phase composite composed of a polymer matrix, electrically conductive nanoparticles and piezoelectric particles. The effective viscoelastic characteristics of a shunted composite are calculated using one- and two-step homogenization procedures and by considering the viscoelastic characteristics of constituent materials. The influence of several key parameters, namely, the non-dimensional frequency, the volume fraction of electrically conductive nanoparticles and piezoelectric particles, and the shape of the inclusions, on viscoelastic characteristics, such as phase angles, the storage modulus and loss modulus, are examined. The viscoelastic characteristics are considerably affected by these parameters, and the perceived behavior is justified by the governing equations. The assessment of results confirms that the damping characteristics can be improved by careful selection of a volume fraction of constituent materials and control of the excitation frequency of the smart composite, while avoiding additional costs and likely inconveniences in the fabrication process.

Pengelompokan Gaya Belajar Secara Homogen dalam Mendukung Pembelajaran Diferensiasi Proses Siswa

Education plays a crucial role in realizing the potential of individuals in various aspects. The learning process is central in bringing about changes in individuals. Different learning styles are a crucial factor in the effectiveness of learning. This research proposes a homogenous learning style grouping approach to support differentiated learning processes in the educational environment. The aim of this research is to explain the importance of understanding students' learning styles and how differentiated learning approaches can maximize their learning potential. The research method used is qualitative, applying a Problem Based Learning (PBL) approach and grouping students based on their learning styles. This study involved 10th-grade students in SMAN Mumbulsari, who exhibited various learning styles, including kinesthetic, auditory, and visual. The research results indicate that the differentiated learning process with student grouping based on their learning styles can enhance student learning activities. Students grouped with similar learning styles have more effective interactions and achieve better learning outcomes. The implications of this research include benefits for both students and teachers, such as improved learning services, fair treatment without discrimination, and the optimal development of students' potential.

A unified approach for the prediction of the effective properties of laminated composite cellular core

The performance of cellular core sandwich panels is influenced significantly by the choice of geometric and material parameters of the cellular core and skins. In order to determine the optimal design of sandwich panels, it is important to relate the geometric and material parameters of the cellular core to the resulting performance of the sandwich panel. Theoretical homogenisation models are computationally efficient and plays an important role in the inverse design of sandwich panel. This paper presents a methodology to determine the equivalent homogenised properties for composite cellular core systems. The methodology was developed based on a strain energy-based homogenisation approach. Unlike other existing models, the proposed model in this paper is applicable to different core shapes and different composite wall layer configurations. An existing model was further extended for comparison purposes to determine the equivalent properties of hexagonal composite honeycomb core. Results from both models were compared with finite element (FE) results for hexagonal honeycomb cores, and the predictions from the proposed model are also compared with FE results for different cellular core shapes. A good agreement was found between the predicted and FE results. The proposed model was found to be superior to existing models in its ability to consider different core shapes and composite wall layer configurations.

In-situ shrinkage measurement of alkali-activated materials using focused ion beam combined with environmental scanning electron microscopy

Drying shrinkage of alkali-activated slag (AAS) has gained significant attention since the volumetric instability of this material can generate premature cracking and degrade the long-term durability of concrete structures. The unique shrinkage behavior of AAS originates mainly from the particular characteristics of its main hydrated products. However, few studies have even at-tempted to investigate the shrinkage behavior of hydrated products in AAS materials. This paper presented a new method of investigating drying shrinkage behavior of AAS using focused ion beam (FIB) combined with environmental scanning electron microscopy (ESEM). This innovative experimental method allowed the in-situ measurement of phase-specific shrinkage. The results showed FIB/ESEM technique can be successfully implemented to cementitious material to prepare phase-specific samples. Furthermore, object-oriented finite element method (OOF2) has been utilized to compute the shrinkage behavior of AAS concrete using a proposed multi-scale scheme. The computations can be made at multi-scales which highlight the effect of hydration products on shrinkage behaviors. OOF2 calculation at the micro-length scale predicted an increase in the shrinkage due to the well-dispersed hydration products inside the matrix. At larger scale, the decrease in the overall shrinkage is related to the extremely low shrinkage value by aggregates. The findings reveal OOF2 offers the capability to accurately measure local stress and strain distribution within heterogeneous materials, a feature notably absent in conventional numerical homogenization approaches. The importance of this benefit is highlighted particularly in the context of free-restrained shrinkage prediction, as conventional homogenization methods fail to account for stress.

Encapsulation of Camphor in Nanocellulose based Pickering Emulsion and Study of its Antibacterial Activity

Abstract: Camphor is a natural and renewable antimicrobial agent. However, it is highly sublime, which limits its practical application as an effective antibacterial agent. To improve camphor's stability and retention properties, we have microencapsulated camphor into an almond essential oil-based Pickering emulsion (AO-PE), stabilized by cellulose nanocrystals (CNC). The CNC was synthesized from corn husk using an eco-friendly homogenization approach to stabilize the AO-PE. Various factors affecting the formation and stability of Pickering emulsions (PE) were studied, such as the source of cellulose (corn husk and mung hull), oil type (sesame oil and almond oil), oil in water concentration, and stability with time and shear. Camphor-loaded CNC-stabilized AO-PE exhibited a small droplet size and had long-term stability at 6.67% by volume oil concentration, owing to the presence of 0.2 g of CNC at droplet interfaces. The results showed that the PE exhibited better antibacterial performance against Staphylococcus aureus than the equivalent concentrations of camphor, almond oil, CNC, and camphor dissolved in almond oil, individually. This research shall provide fresh insights into the significant enhancement of the antimicrobial properties of medicinal natural products by incorporating them into PEs. Graphical abstract

A multiscale approach in modeling of chemically reactive porous media

Chemical reactions occur in geotechnical, biological and synthetic porous media. Swelling and shrinkage phenomena can be observed in clays, shales and gels, when they are in close contact with water. In petroleum engineering, wellbore-stability problems are caused by swelling or shrinking of the wellbore. Thus, it is significant to model the Chemo-Hydro-Mechanical (CHM) processes in porous media that include different physical and geometrical heterogeneities. In this paper, a multiscale computational homogenization approach is developed for the analysis of CHM problems. In this manner, the first-order homogenization technique is adopted for the two-scale formulation. The heterogeneities are assumed in the microscale level and a homogeneous domain is considered for the macroscale level, where the constitutive behavior is derived from the microscopic level. The governing equations and constitutive equations of the CHM processes are presented in the coupled manner. The primary variables are taken as the displacement, pore pressure, and solute concentration fields. Moreover, the transient terms are included in the microscale level to increase the accuracy of computations. Consequently, a generalized form of Hill-Mandel principle of macro-homogeneity is defined between the two scales. Appropriate microscopic boundary conditions, i.e. the linear and periodic boundary conditions, are employed to satisfy the averaging constraints. Finally, the accuracy and efficiency of the proposed computational multiscale method are illustrated through several numerical examples.

Phase field method based on reduced-order-homogenization for fibrous composite material

This manuscript proposes a novel multiscale phase field method (PFM) based on reduced-order-homogenization (ROH) approach to investigate the damage evolution for the fibrous composite material, namely the ROH-PFM. In the ROH-PFM, the matrix phase is described by the PFM, and the fiber phase could be modeled by some other classic constitutive model. The overall response of the fibrous composite material then is obtained by averaging and homogenization approaches through the ROH framework in order to obtain the macro-scopic stress and consistent material moduli. In the present work, we derive the governing equations in terms of the displacement field and the matrix phase field. Through the ROH and the Francfort–Marigo variational principle, we can obtain the governing elliptical partial differential equation for the matrix phase field in terms of the stress states of the matrix and fiber phases. The corresponding weak form is derived, and numerical algorithm through the finite element method is derived as well. Finally, three groups of numerical simulations are selected to verify the functionality of the ROH-PFM, while the fibers are assumed to follow an isotropic continuum damage model. The numerical examples show good performance of the ROH-PFM in stating various material degradation mechanism.

Scale transition and residual fields in modeling of polycrystalline ferroelectrics based on the internal energy potential and a Voigt–Reuss approximation

A multiscale constitutive model, implemented within a semi-analytical computational framework, is presented. Accounting for domain switching in a tetragonal lattice and electromechanical intergranular interactions, it aims to accurately reproduce experimental data available from butterfly and dielectric hysteresis loops. For the sake of validation, these have been collected from various sources providing ranges of values for characteristic quantities. Adopting the fundamental ideas of a previously published model, a different homogenization approach is employed for the transition from grain to polycrystalline domain, providing both residual stress and electric fields. Furthermore, the thermodynamic driving force and constitutive equations on the grain level are based on a different thermodynamical potential. While the modeling approach inherently does not include any tuning parameters, the introduction of one and two, respectively, additional parameters is investigated, although computational results are basically in good agreement with experimental ranges.

Impact of parametric variation to achieve extreme mechanical metamaterials through topology optimization

Metamaterials are manufactured structures having extreme properties which do not exist in nature. Topology optimization (TO) provides an excellent alternative to the intuition-based homogenization approach used in commercial packages for automating the design of metamaterials. However, multiple topological parameters must be decided to get the tailored effective properties. This research aims to study the optimum parameters to be used in TO for developing incompressible material. To achieve this, we design microstructures to maximize the bulk modulus. A number of parametric studies are performed by varying topological control parameters such as volume fraction, penalization power, filter radius, mesh size and initial design. In addition to this, the combinations of these parameters are also investigated. These studies will be helpful for the design of incompressible metamaterials. The bulk modulus for topologically optimized designs approaches the Hashin–Shtrikman upper bound (HSUB). The results show that appropriate parameter selection can significantly improve the microstructure’s incompressibility. Such materials can have potential applications in designing aerospace and energy-absorbing components.

Bimetallic cobalt–nickel supported on carbon fiber for electrochemical simultaneous determination of dopamine and hydroquinone

Bimetallic cobalt–nickel supported on carbon fiber (Co-Ni@CF) was synthesized by a straightforward homogeneous co-precipitation approach. Electrochemical results demonstrated that the modified Co-Ni@CF electrode demonstrated excellent electrooxidation activity toward dopamine (DA) and hydroquinone (HQ) without any other activating treatments, which could be modified as an electrochemical biosensor for DA and HQ detection simultaneously. The as-proposed biosensor was developed for simultaneous detection of DA and HQ, featuring low detection limits (LODs) of 0.4698 μM for DA and 0.2388 mM for HQ, respectively. The sensor also offers broad linear ranges for DA (5.0–30 μM), and HQ (0.5–5.0 mM). Along with these attractive features, the Co-Ni@CF electrode also performed good long-term stability and reproducibility, making it a promising candidate for electrochemical biosensing of DA and HQ.

A data-based derivation of the internal stress in the discrete-continuum transition regime of dislocation based plasticity

Effectively homogenizing microstructure heterogeneity within the coarse-graining volume is a long-lasting challenge in crystal plasticity theories. In this paper, we propose a data-based homogenization method that utilizes discrete dislocation dynamic simulations to derive the nearfield correction stress (back stress) for continuum models. This stress accounts for the effective stress field induced by microstructure heterogeneity under the length scale of a coarse-graining volume, providing a physically based homogenization approach. To bridge the gap between discrete and continuous regimes, we introduce two versions of the nearfield correction stress, as well as a criterion based on microstructure and numerical parameters to determine the discrete and continuous transition. Moreover, by analyzing the mathematical connections with the work-conjugated gradient plasticity theory, we further provide a physical explanation for the observed material length scale in the thermodynamically consistent back stress term. This work presents a novel methodology for effectively addressing microstructure heterogeneity and advancing the understanding and modeling of material behavior bridging different length scales.

A homogeneous composite approach for improved thermoelectric performance: Repressing lattice thermal conductivity in substoichiometric WO2.90 and WO2.72

Nanostructured phonon-glass thermoelectric materials are highly sought after for heat waste recovery applications. This work introduces a novel phonon-glass multi-phase ceramic material synthesized from sintered mixtures of two sub-stoichiometric tungsten oxides, WO2.90 and WO2.72. Notable measurements were recorded for our sample, denoted as 0.1WO2.72/0.9WO2.90, at 800 °C, with S2σ = 0.51 ± 0.03 mWm−1K−2, representing a tenfold increase compared to the base materials. The lattice thermal conductivity, already displaying phonon-glass characteristics, is further suppressed by the addition of the secondary WO2.72 pentacolumn phase, reaching its lowest value at 0.54 ± 0.25 Wm−1K−1. As a result, the ZT value is enhanced to twice the intrinsic value of the pristine phase. This study demonstrates a novel strategy for improving the thermoelectric performance of oxide-based materials by leveraging a synergistic relationship among several key factors, including phonon-glass nanostructures, tunable electrical properties, and the reduction of lattice thermal conductivity within a homogeneous composite system.

A representative volume element model to evaluate the effective properties of flexoelectric nanocomposite

In this paper, a computational homogenization approach is developed to investigate the effective material properties of flexoelectric nanocomposites. The analysis incorporates the isogeometric analysis (IGA) to solve an electromechanically coupled system using a 3D representative volume element (RVE) model with periodic boundary conditions. In particular, a micromechanical analysis is carried out to represent the microstructure of a heterogeneous domain composed of an elastic matrix and cylindrical flexoelectric fibers. The numerical simulations indicated that while the effective tensor of piezoelectricity is isotropic, the flexoelectricity tensor is transversely anisotropic concerning the geometry of the composite’s phases. Furthermore, the flexoelectricity coefficients, μ¯3113 and μ¯3333, which couple the polarization to the strain gradients with respect to the longitudinal axis, improved remarkably with increasing the inclusion’s volume fraction. The presented computational methodology and the findings of this study is expected to contribute valuably towards the design of flexoelectric nanostructures and devices.

Logistic Regression to Predict Heart Disease

The early diagnosis of cardiovascular disorders can help high risk individuals make decisions about lifestyle adjustments, which can lessen their problems. Using homogeneous data mining approaches, research has sought to identify the most significant risk variables for heart disease as well as reliably estimate the total risk. Recent studies have looked into combining these methods utilizing strategies like hybrid data mining algorithms. In order to offer an accurate model for predicting heart disease, this study suggests a rule-based model to evaluate the accuracy of applying rules to the individual findings of logistic regression, decision trees, and support vector machines on the Cleveland Heart Disease Database. KEYWORDS- Heart disease, support vector machine (SVM), logistic regression, decision trees, and rule based approach

Mechanical performance of 3D-printed continuous fibre Onyx composites for drone applications: An experimental and numerical analysis

As drone technology grows in popularity, its application to automate aspects of society is increasing at a similar rate, where drones are now being trialled for delivering payloads over short distances. In order to progress the technology, 3D composite printing is being used to develop complicated parts for improved aerodynamic design that can be produced efficiently, where the resultant composite part has high specific strength and rigidity. This article reports 3D printing of high specific strength, high-temperature Polyamide 6 (Onyx), continuous glass-fibre reinforced Onyx, and carbon-fibre reinforced Onyx composites and characterising their mechanical and fracture behaviour. The Onyx + CF composites displayed up to 1243 % and 1344 % improvement in Young's modulus and tensile strength over neat Onyx samples. The flexural strength of Onyx + CF samples was up to 316.6 % higher than the flexural strength of the neat Onyx sample. SEM micrographs showed a strong bond between the hydration products and the carbon fibres, increasing their tensile and flexural strengths by preventing micro-crack propagation through fibre pull-out and breaking. The statistical analysis was conducted to ensure the validity of the results for the population and establish stress-strain relations, along with estimating errors. In addition, the carbon-fibre-reinforced Onyx composite was compared with commercially used alternatives for producing drone components. Finally, a finite element model was developed using a numerical homogenisation approach and validated to predict the tensile and flexural behaviour of Onyx and carbon-fibre reinforced Onyx samples. This study provides a direction for the next generation of drone manufacturers.

Interface Homogenization Approach for Mechanical Healing Driven by Pressure Solution

Interface Homogenization Approach for Mechanical Healing Driven by Pressure Solution

Absolute nodal coordinate formulation – Multilevel finite element framework for the nonlinear multi-scale multibody dynamic analysis of composite structures

In this paper, a multi-scale modeling approach for the dynamic response of flexible multibody system made of composite material is suggested using the absolute nodal coordinate formulation (ANCF) – multilevel finite element (FE2) method. On many occasions, the analysis of composite structures requires a multi-scale modeling approach. FE2 method is one of the famous multi-scale modeling methods. And it is a versatile computational homogenization approach that is commonly applicable to many different materials. Because the present FE2 is capable of computing the mechanical response at two different scales simultaneously, ANCF element will be used at the macroscopic scale. And the microscopic RVE at each macroscopic integration point will be obtained by the finite element method. Since ANCF element uses only the absolute nodes and gradients, the mass matrix will be constant. Due to such characteristics, when combined with FE2, the linearization process will become easier compared against the existing formulation. And Coriolis or centrifugal force will not need to be considered in the dynamic formulation. Therefore, computational cost will be reduced, and the relevant algebraic manipulation will become simplified. Several numerical examples are presented to demonstrate the improved accuracy and diminished computational cost of the present suggestion.