Latest Publications

Abstract:
In view of the demand for accurate modal identification, and based on the characteristics of free vibration response, this paper introduces a new window function for Fourier Transform called the Power–Exponential window. The Power–Exponential window addresses the characteristics of free vibration response. It significantly enhances the accuracy of modal identification by improving the spectral properties of structural response. The proposed window function consists of exponential and power terms. This study focuses on the additional damping and frequency-domain differentiation introduced by the Power–Exponential window function. The exponential term weakens the boundary effect related to the time-domain truncation and suppresses the spectral leakage. Moreover, it can be interpreted in clear physical terms as providing additional damping to the signal. The power term in the window function corresponds to frequency domain differentiation, and it alleviates the spectral broadening that arises due to the additional damping. Furthermore, the analytical expression for the response spectrum confirms that the Power–Exponential window not only aligns the peak response frequency with the damped natural frequency but also establishes an explicit linear relationship between the actual structural damping ratio and the identification result from the half power bandwidth method. Both contribute to an improved accuracy and usability of certain frequency-domain modal identification methods. The influence of the Power–Exponential window parameters on modal parameter identification is analyzed, and the optimal selection principle and suggested parameter values are proposed. Finally, numerical simulations and an experimental frame model test are conducted to verify the accuracy and validity of modal parameter identification based on the Power–Exponential window.

Keywords:
Modal identification, Window function, Frequency domain, Spectrum leakage, Fourier Transform (FT)

Abstract:
This paper introduces MorphoGen — an integrated reliability-based topology optimization and nonlinear finite element analysis system for 2D and 3D domains. The system’s key innovation is its seamless prototyping of scientific formulations for computational problems in topology optimization. Its layered and object-oriented architecture, based on the template method design pattern, facilitates effortless modifications of algorithms and the introduction of new types of finite elements, materials, and analyses. MorphoGen also offers flexible handling of objective functions and constraints during topological optimization, enhancing its adaptability. It empowers researchers and practitioners to explore a wide range of engineering challenges, fostering a deeper understanding of complex structural behaviors and efficient design solutions. There are many topology optimization software and open source codes, especially based on the classical SIMP method. Unlike these codes our package is freely distributed among users and since it is distributed on the MIT licence, which allows for its easy modification depending on the particular needs of the users. For this purpose, we use the topology optimization algorithm proposed for the first time in our previous paper (Blachowski et al., 2020). The algorithm is based on a fully stress design-based optimality criteria and can be applied for topology optimization of either linearly elastic and elastoplastic structures. Additionally, the novelty of the proposed system is related to its ability of solving optimal topology under various constraints such as displacement, stresses and fatigue in both deterministic and probabilistic cases. Another application are modular structures, which reduce design complexity and manufacturing costs as well as rapid reconfiguration. However, in the realm of structural optimization, modular systems are more challenging due to various: modes of operation of the modules and the stresses configurations. Moreover, this area of research is dramatically less explored. Thus the effectiveness of MorphoGen for structural engineering is demonstrated with examples of topological shape optimization of two Extremely Modular Systems: a planar robotic manipulator Arm-Z and spatial free-form ramp Truss-Z.

Keywords:
Stress Constrained Topology Optimizatio,Extremely Modular System,Object-oriented software architecture,MATLAB-based array programming,First Order Reliability Analysis

Abstract:
In this paper, an assessment of a topography measurement method for fracture surfaces of 10HNAP steel after bending-torsion fatigue tests was performed. Surface roughness was measured by using a non-contact Focus Variation Microscopy (FVM) technique in which the non-measured points (NMPs) and outliers (spikes) were removed by the application of general methods. The results revealed, that the optical measurement method introduced variations in the high-frequency errors, considered as noise within the selected bandwidth. Therefore, the minimization of the high-frequency noise (HFN) was proposed based on an extensive examination of ISO 25178 roughness parameters. Additionally, a general S-filter was applied, as recommended by international standards and commercial software. It was used to identify and remove noise from the measured data after pre-processing. Consequently, levelling and eliminating of NMPs and spikes was successfully performed. Subsequently, the results obtained by using various filters were compared to further assess the impact of different filtration bandwidths. Finally, the proposed procedure was validated by implementing different general functions, such as autocorrelation (ACF), power spectral densities (PSD), and texture direction (TD). It was concluded, that coupled characteristics, including profile and areal measurements, should be studied simultaneously since they are necessary to analyze the fracture surfaces comprehensively.

Keywords:
bending-torsion fatigue ,surface topography ,roughness ,non-measured points ,outliers ,high-frequency noise,measurement errors

Abstract:
Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex etiology that lacks effective treatment. The therapeutic goals include alleviating symptoms, such as moisturizing and applying antibacterial and anti-inflammatory medications. Hence, there is an urgent need to develop a patch that effectively alleviates most of the AD symptoms. In this study, we employed a “green” cross-linking approach of poly(vinyl alcohol) (PVA) using glycerol, and we combined it with polyacrylonitrile (PAN) to fabricate core–shell (CS) nanofibers through electrospinning. Our designed structure offers multiple benefits as the core ensures controlled drug release and increases the strength of the patch, while the shell provides skin moisturization and exudate absorption. The efficient PVA cross-linking method facilitates the inclusion of sensitive molecules such as fermented oils. In vitro studies demonstrate the patches’ exceptional biocompatibility and efficacy in minimizing cell ingrowth into the CS structure containing argan oil, a property highly desirable for easy removal of the patch. Histological examinations conducted on an ex vivo model showed the nonirritant properties of developed patches. Furthermore, the eradication of Staphylococcus aureus bacteria confirms the potential use of CS nanofibers loaded with argan oil or norfloxacin, separately, as an antibacterial patch for infected AD wounds. In vivo patch application studies on patients, including one with AD, demonstrated ideal patches’ moisturizing effect. This innovative approach shows significant promise in enhancing life quality for AD sufferers by improving skin hydration and avoiding infections.

Keywords:
atopic dermatitis, core−shell electrospun nanofibers, antibacterial, mucoadhesive, moisturizing patch

Abstract:
A new generation of an FFP2 (Filtering Face Piece of type 2) smart face mask is achieved by integrating broadband hybrid nanomaterials and a self-assembled optical metasurface. The multifunctional FFP2 face mask shows simultaneously white light-assisted on-demand disinfection properties and versatile biosensing capabilities. These properties are achieved by a powerful combination of white light thermoplasmonic responsive hybrid nanomaterials, which provide excellent photo-thermal disinfection properties, and optical metasurface-based colorimetric biosensors, with a very low limit of pathogens detection. The realized system is studied in optical, morphological, spectroscopic, and cell viability assay experiments and environmental monitoring of harmful pathogens, thus highlighting the extraordinary properties in reusability and pathogens detection of the innovative face mask.

Abstract:
Functionally graded metal matrix composites have attracted the attention of various industries as materials with tailorable properties due to spatially varying composition of constituents. This research work was inspired by an application, such as automotive brake disks, which requires advanced materials with improved wear resistance on the outer surface as combined with effective heat flux dissipation of the graded system. To this end, graded AlSi12/Al2O3 composites (FGMs) with a stepwise gradient in the volume fraction of alumina reinforcement were produced by hot pressing and spark plasma sintering techniques. The thermal conductivities of the individual composite layers and the FGMs were evaluated experimentally and simulated numerically using 3D finite element (FE) models based on micro-computed X-ray tomography (micro-XCT) images of actual AlSi12/Al2O3 microstructures. The numerical models incorporated the effects of porosity of the fabricated AlSi12/Al2O3 composites, thermal resistance, and imperfect interfaces between the AlSi12 matrix and the alumina particles. The obtained experimental data and the results of the numerical models are in good agreement, the relative error being in the range of 4 to 6 pct for different compositions and FGMstructure. The predictive capability of the proposed micro-XCT-based FE model suggests that this model can be applied to similar types of composites and different composition gradients.

Abstract:
Estimation of macroscopic properties of heterogeneous materials has always posed significant problems. Procedures based on numerical homogenization, although very flexible, consume a lot of time and computing power. Thus, many attempts have been made to develop analytical models that could provide robust and computationally efficient tools for this purpose. The goal of this paper is to develop a reliable analytical approach to finding the effective elastic–plastic response of metal matrix composites (MMC) and porous metals (PM) with a predefined particle or void distribution, as well as to examine the anisotropy induced by regular inhomogeneity arrangements. The proposed framework is based on the idea of Molinari & El Mouden (1996) to improve classical mean-field models of thermoelastic media by taking into account the interactions between each pair of inhomogeneities within the material volume, known as a cluster model. Both elastic and elasto-plastic regimes are examined. A new extension of the original formulation, aimed to account for the non-linear plastic regime, is performed with the use of the modified tangent linearization of the metal matrix constitutive law. The model uses the second stress moment to track the accumulated plastic strain in the matrix. In the examples, arrangements of spherical inhomogeneities in three Bravais lattices of cubic symmetry (Regular Cubic, Body-Centered Cubic and Face-Centered Cubic) are considered for two basic material scenarios: “hard-in-soft” (MMC) and “soft-in-hard” (PM). As a means of verification, the results of micromechanical mean-field modeling are compared with those of numerical homogenization performed using the Finite Element Method (FEM). In the elastic regime, a comparison is also made with several other micromechanical models dedicated to periodic composites. Within both regimes, the results obtained by the cluster model are qualitatively and quantitatively consistent with FEM calculations, especially for volume fractions of inclusions up to 40%.

Keywords:
Periodic composite , Micro-mechanics , Effective properties, Elasto-plasticity, Particle interactions

Abstract:
Mutagenesis is responsive to many environmental factors. Evolution therefore depends on the environment not only for selection but also in determining the variation available in a population. One such environmental dependency is the inverse relationship between mutation rates and population density in many microbial species. Here, we determine the mechanism responsible for this mutation rate plasticity. Using dynamical computational modelling and in culture mutation rate estimation, we show that the negative relationship between mutation rate and population density arises from the collective ability of microbial populations to control concentrations of hydrogen peroxide. We demonstrate a loss of this density-associated mutation rate plasticity (DAMP) when Escherichia coli populations are deficient in the degradation of hydrogen peroxide. We further show that the reduction in mutation rate in denser populations is restored in peroxide degradation-deficient cells by the presence of wild-type cells in a mixed population. Together, these model-guided experiments provide a mechanistic explanation for DAMP, applicable across all domains of life, and frames mutation rate as a dynamic trait shaped by microbial community composition.

Abstract:
Structural schemes of applicative interests in Engineering Science frequently encounter the intricate phenomenon of discontinuity. The present study intends to address the discontinuity in the flexure of elastic nanobeam by adopting an abstract variational scheme. The mixture unified gradient theory of elasticity is invoked to realize the size-effects at the ultra-small scale. The consistent form of the interface conditions, stemming from the established stationary variational principle, is meticulously set forth. The boundary-value problem of equilibrium is properly closed and the analytical solution of the transverse displacement field of the elastic nanobeam is addressed. As an alternative approach, the eigenfunction expansion method is also utilized to scrutinize the efficacy of the presented variational formulation in tackling the flexure of elastic nanobeams with discontinuity. The flexural characteristic of mixture unified gradient beams with diverse kinematic constraints is numerically illustrated and thoroughly discussed. The anticipated nanoscopic features of the characteristic length-scale parameters are confirmed. The demonstrated numerical results can advantageously serve as a benchmark for the analysis and design of pioneering ultra-sensitive nano-sensors. The established variationally consistent size-dependent framework paves the way ahead in nanomechanics and inspires further research contributing to fracture mechanics of ultra-small scale elastic beams.

Abstract:
The macroscopic behaviors of materials are determined by interactions that occur at multiple lengths and time scales. Depending on the application, describing, predicting, and understanding these behaviors may require models that rely on insights from atomic and electronic scales. In such cases, classical simplified approximations at those scales are insufficient, and quantum-based modeling is required. In this paper, we study how quantum effects can modify the mechanical properties of systems relevant to materials engineering. We base our study on a high-fidelity modeling framework that combines two computationally efficient models rooted in quantum first principles: Density Functional Tight Binding (DFTB) and many-body dispersion (MBD). The MBD model is applied to accurately describe non-covalent van der Waals interactions. Through various benchmark applications, we demonstrate the capabilities of this framework and the limitations of simplified modeling. We provide an open-source repository containing all codes, datasets, and examples presented in this work. This repository serves as a practical toolkit that we hope will support the development of future research in effective large-scale and multiscale modeling with quantum-mechanical fidelity.

Keywords:
DFT, DFTB, Energy range separation, Many-body dispersion, van der Waals interaction, Carbon nanotube, UHMWPE

Abstract:
This work presents a comprehensive examination of the physical mechanisms driving hardening in irradiated face-centered cubic FeNiCr alloys. The evolution of irradiation-induced defects during shear deformation is modeled by atomistic simulations through overlapping cascade simulations, where the nucleation and evolution of dislocation loops is validated by transmission electron microscopy images obtained from irradiated FeNiCr alloys using tandem accelerator. The effect of different shear rates on the microstructure of irradiated materials with a specific focus on the changes in the density of voids and dislocation loops induced by irradiation was analyzed. Additionally, the fundamental interaction processes between single irradiation-induced defects contributing to irradiation hardening, such as voids and dislocation loops in the alloy are explained. The analysis at atomic level indicates that both the dislocation loops and the voids exhibit strengthening effects. Furthermore, the nanometric voids are much stronger obstacles than dislocation loops of comparable size. The mechanism of cutting the voids leads to an increase of voids density and thus contributes to an increase in irradiation hardening. The mechanism of collapse of small voids into dislocation loops leads to decrease of voids density and at the same time increase of loops density. The coupling effect between the density of voids and dislocation loops is determined. Finally, the novel, physical mechanisms-based model of irradiation hardening and dislocation-radiation defect reaction kinetics are developed, which consider the mechanisms of void cutting, void shrink and void collapse to dislocation loop.

Keywords:
Radiation-induced defects,Irradiation hardening,Collision cascades,MD simulations,Radiation defects evolution,Cr-rich alloys

Abstract:
Intervertebral disc (IVD) degeneration is a leading cause of lower back pain (LBP). Current treatments primarily address symptoms without halting the degenerative process. Cell transplantation offers a promising approach for early-stage IVD degeneration, but challenges such as cell viability, retention, and harsh host environments limit its efficacy. This study aimed to compare the injectability and biocompatibility of human nucleus pulposus cells (hNPC) attached to two types of microscaffolds designed for minimally invasive delivery to IVD. Microscaffolds are developed from poly(lactic-co-glycolic acid) (PLGA) using electrospinning and femtosecond laser structuration. These microscaffolds are tested for their physical properties, injectability, and biocompatibility. This study evaluates cell adhesion, proliferation, and survival in vitro and ex vivo within a hydrogel-based nucleus pulposus model. The microscaffolds demonstrate enhanced surface architecture, facilitating cell adhesion and proliferation. Laser structuration improved porosity, supporting cell attachment and extracellular matrix deposition. Injectability tests show that microscaffolds can be delivered through small-gauge needles with minimal force, maintaining high cell viability. The findings suggest that laser-structured PLGA microscaffolds are viable for minimally invasive cell delivery. These microscaffolds enhance cell viability and retention, offering potential improvements in the therapeutic efficiency of cell-based treatments for discogenic LBP.

Abstract:
The long-time behavior of highly elastic fibers in a shear flow is investigated experimentally and numerically. Characteristic attractors of the dynamics are found. It is shown that for a small ratio of bending to hydrodynamic forces, most fibers form a spinning elongated double helix, performing an effective Jeffery orbit very close to the vorticity direction. Recognition of these oriented shapes, and how they form in time, may prove useful in the future for understanding the time history of complex microstructures in fluid flows and considering processing steps for their synthesis.

Keywords:
Stokes equations, shear flow, elastic fibers

Abstract:
Detection of lysozyme levels in ocular fluids is considered crucial for diagnosing and monitoring various health and eye conditions, including dry-eye syndrome. Hydrogel-based nanocomposites have been demonstrated to be one of the most promising platforms for fast and accurate sensing of different biomolecules. In this work, hydrogel, electrospun nanofibers, and plasmonic nanoparticles are combined to fabricate a sensitive and easy-to-use biosensor for lysozyme. Poly(L-lactide-co-caprolactone) (PLCL) nanofibers were covered with silver nanoplates (AgNPls), providing a stable plasmonic platform, where a poly(N-isopropylacrylamide)-based (PNIPAAm) hydrogel layer allows mobility and good integration of the biomolecules. By integrating these components, the platform can also exhibit a colorimetric response to the concentration of lysozyme, allowing for easy and non-invasive monitoring. Quantitative biosensing operates on the principle of localized surface plasmon resonance (LSPR) induced by plasmonic nanoparticles. Chemical, structural, thermal, and optical characterizations were performed on each platform layer, and the platform's ability to detect lysozyme at concentrations relevant to those found in tears of patients with dry-eye syndrome and other related diseases was investigated by colorimetry and UV-Vis spectroscopy. This biosensor's sensitivity and rapid response time, alongside the easy detection by the naked eye, make it a promising tool for early diagnosis and treatment monitoring of eye diseases.

Abstract:
This paper describes an application of a machine learning approach for parameter optimization. The method is demonstrated for the elasto-viscoplastic model with both isotropic and kinematic hardening. It is shown that the proposed method based on long short-term memory networks allowed a reasonable agreement of stress–strain curves to be obtained for cyclic deformation in a low-cycle fatigue regime. The main advantage of the proposed approach over traditional optimization schemes lies in the possibility of obtaining parameters for a new material without the necessity of conducting any further optimizations. As the power and robustness of the developed method was demonstrated for very challenging problems (cyclic deformation, crystal plasticity, self-consistent model and isotropic and kinematic hardening), it is directly applicable to other experiments and models.

Keywords:
crystal plasticity, optimization, machine learning, long short-term memory networks, self-consistent modeling, Eshelby solution, cyclic deformation, low cycle fatigue

Abstract:
In this paper, the entire fracture surface approach was used to assess an effect of 280,000 h of exploitation under internal pressure of 2.9 MPa and high temperature of 540 °C on the fatigue response of 10H2M (10CrMo9–10) power engineering steel. The mechanical testing was carried out on the hourglass specimens produced from the as-received, unused pipeline and the same material after long-time exploitation. The uniaxial tensile tests were performed to establish the stress amplitude for subsequent force controlled, fatigue testing in the range from ±250 MPa to ±400 MPa under the frequency of 20 Hz. Since the exploited 10H2M steel was characterized by significantly lower mechanical properties, different damage mechanisms responsible for specimen failure were revealed through fracture surface analysis. The fracture surface topography evaluation was performed with a 3D non-contact measuring system. It was found, that the exploitation state has a strong impact on the fatigue life and fracture characteristics since the significant drop in lifespan of about 300 %–400 % was found for the material after prolonged service. Finally, the proposed surface topography parameter was related to the stress amplitude in order to estimate the fatigue life for the steel in question.

Keywords:
fatigue , 10H2M steel , Mechanical properties , Surface topography

Abstract:
Metal matrix composites (MMCs) combine metal with ceramic reinforcement, offering high strength, stiffness, corrosion resistance, and low weight for diverse applications. Al-SiC, a common MMC, consists of an aluminum matrix reinforced with silicon carbide, making it ideal for the aerospace and automotive industries. In this work, molecular dynamics simulations are performed to investigate the mechanical properties of the complex-shaped models of Al-SiC. Three different volume fractions of SiC particles, precisely 10%, 15%, and 25%, are investigated in a composite under uniaxial tensile loading. The tensile behavior of Al-SiC composites is evaluated under two loading directions, considering both cases with and without diffusion effects. The results show that diffusion increases the ultimate tensile strength of the Al-SiC composite, particularly for the 15% SiC volume fraction. Regarding the shape of the SiC particles considered in this research, the strength of the composite varies in different directions. Specifically, the ultimate strength of the Al-SiC composite with 25% SiC reached 11.29 GPa in one direction, and 6.63 GPa in another, demonstrating the material’s anisotropic mechanical behavior when diffusion effects are considered. Young’s modulus shows negligible change in the presence of diffusion. Furthermore, diffusion improves toughness in Al-SiC composites, resulting in higher values compared to those without diffusion, as evidenced by the 25% SiC volume fraction composite (2.086 GPa) versus 15% (0.863 GPa) and 10% (1.296 GPa) SiC volume fractions.

Keywords:
Molecular dynamics, Al-SiC composites, Diffusion, SiC particle

Abstract:
Localization of the stress-induced martensitic phase transformation plays an important role in the fatigue behavior of shape memory alloys (SMAs). The phenomenon of return-point memory that is observed during the subloop deformation of a partially-transformed SMA is a clear manifestation of the interaction between localized phase transformation and degradation of the functional properties. The present study aims to demonstrate this structure–material interaction in the modeling of return-point memory. It seems that this crucial aspect has been overlooked in previous modeling studies. For this purpose, we developed a gradient- enhanced model of pseudoelasticity that incorporates the degradation of functional properties in its constitutive description. The model is employed to reproduce the hierarchical return-point memory in a pseudoelastic NiTi wire under isothermal uniaxial tension with nested subloops. Additionally, a detailed analysis is carried out for NiTi strip with a more complex transformation pattern. Our study highlights the subtle morphological changes of phase transformation under different loading scenarios and the resulting implications for return-point memory.

Keywords:
Shape memory alloys,Phase transformation,Functional degradation ,Propagating instabilities,Subloop deformation,Modeling

Abstract:
In this paper, strain evolution of 13HMF power engineering steel was analysed during force-controlled low cycle fatigue (LCF). The material performance under cyclic loading was monitored by using Digital Image Correlation (DIC) technique for different values of stress amplitude exceeding the yield strength of the material significantly. Data collected from DIC was compared to the extensometer ones to confirm the effectiveness of the proposed approach. Finally, the cloud data reflecting the fatigue performance of 13HMF was generated in the form of strain-stress amplitude - service life distribution map.

Keywords:
Fatigue,Mechanical properties,Strain analysis

Abstract:
This study presents a general computational framework for topology optimization under constraints related to various engineering design problems, including: reliability analysis, low-cycle fatigue assessment, and stress limited analysis. Such a framework aims to facilitate comprehensive engineering design considerations by incorporating traditional constraints such as displacement and stress alongside probabilistic assessments of fatigue failure and the complex behaviors exhibited by structures made of elastoplastic material. The framework's amalgamation of diverse analytical components offers engineers a versatile toolkit to address intricate design challenges. Notably, the inclusion of reliability analysis introduces a probabilistic perspective, transforming conventional design constraints into random parameters, thereby enhancing the robustness of the design process.

Key to the framework's efficacy is its implementation using MATLAB mathematical computing software, leveraging the platform's efficient code execution and object-oriented programming paradigm. This choice ensures an intuitive and potent environment for designers and researchers, facilitating seamless adaptation across various engineering applications. Additionally, the proposed previously by the Authors algorithm for the topology optimization is extended by adaptive strategy allowing for efficient adjustment of an amount of material removed at individual optimization step.

The presented framework is offering a comprehensive and integrated approach to address multifaceted design challenges while enhancing design robustness and efficiency.

Keywords:
Topology optimization, Stress constraints, First order reliability analysis, Low-cycle fatigue, Plasticity

Abstract:
An alkali–silica reaction (ASR) is a chemical process that leads to the formation of an expansive gel, potentially causing durability issues in concrete structures. This article investigates the properties and behaviour of ASR products in mortar with the addition of low-purity calcined clay as an additional material. This study includes an evaluation of the expansion and microstructural characteristics of the mortar, as well as an analysis of the formation and behaviour of ASR products with different contents of calcined clay. Expansion tests of the mortar beam specimens were conducted according to ASTM C1567, and a detailed microscopic analysis of the reaction products was performed. Additionally, their mechanical properties were determined using nanoindentation. This study reveals that with an increasing calcined clay content, the amount of the crystalline form of the ASR gel decreases, while the nanohardness increases. The Young’s modulus of the amorphous ASR products ranged from 5 to 12 GPa, while the nanohardness ranged from 0.41 to 0.67 GPa. The obtained results contribute to a better understanding of how the incorporation of low-purity calcined clay influences the ASR in mortar, providing valuable insights into developing sustainable and durable building materials for the construction industry.

Keywords:
alkali–silica reaction, ASR products, calcined clay, mortar, expansion

Abstract:
Stainless steel 316L tubes and bars were additively manufactured (AM) by using the Laser Powder Bed Fusion Melting (LPBF-M) method in three orientations. As-built specimens were then machined and the initial yield surface was determined for three printing orientations based on the yield stress definition for 0.005 % plastic offset strain. The as-received, wrought material was additionally tested using the same tension–compression-torsion conditions to compare the mechanical behaviour of AM and wrought SS316L. The sizes of yield surfaces elaborated for LPBF-M specimens increased along the tensile and compressive directions and shrunk when torsion was applied, as compared to the as-received specimen.

Keywords:
Stainless steel ,Yield surface ,Additive manufacturing

Abstract:
The HIFU ablation technique is limited by the long duration of the procedure, which results from the large difference between the size of the HIFU beam’s focus and the tumor size. Ablation of large tumors requires treating them with a sequence of single HIFU beams, with a specific time interval in-between. The aim of this study was to evaluate the biological effects induced in a malignant solid tumor of the rat mammary gland, implanted in adult Wistar rats, during HIFU treatment according to a new ablation plan which allowed researchers to significantly shorten the duration of the procedure. We used a custom, automated, ultrasound imaging-guided HIFU ablation device. Tumors with a 1 mm thickness margin of healthy tissue were subjected to HIFU. Three days later, the animals were sacrificed, and the HIFU-treated tissues were harvested. The biological effects were studied, employing morphological, histological, immunohistochemical, and ultrastructural techniques. Massive cell death, hemorrhages, tissue loss, influx of immune cells, and induction of pro-inflammatory cytokines were observed in the HIFU-treated tumors. No damage to healthy tissues was observed in the area surrounding the safety margin. These results confirmed the efficacy of the proposed shortened duration of the HIFU ablation procedure and its potential for the treatment of solid tumors.

Keywords:
HIFU thermal ablation, breast cancer model, treatment plan, morphology, histology, ultrastructure, immune response, cell death, apoptosis, necrosis

Abstract:
This study presents the process of developing an effective anode material for lithium-ion batteries (LIBs) by usage of Li2TiSiO5 coated with a thin layer of carbon (LTSO/C). The material was prepared through a sol–gel method, where varying amounts of polyvinylpyrrolidone (PVP) were used as a carbon source during the synthesis process. The physicochemical analysis of the LTSO/C samples indicates that as the amount of PVP used during sol–gel synthesis increases, the particle diameter of LTSO decreases. Furthermore, the analysis shows that a thin amorphous carbon layer is deposited on the LTSO surfaces, along with additional carbon networks between the LTSO particles. Based on the electrochemical analysis conducted to optimize the amount of PVP during synthesis, the resulting LTSO/C composite electrode synthesized with 1 g of PVP exhibits a specific capacity of 274.5 mAh·g−1 at 0.1C after 150 cycles, which is quite close to the theoretical capacity. In addition, this LTSO/C electrode demonstrates exceptional electrochemical performance when operated at high rates, surpassing a discharge capacity of 170 mAh g−1 up to 2C. Therefore, the LTSO/C is an excellent choice for high-performance anode material in LIBs.

Keywords:
Li2TiSiO5, Carbon layer, Polyvinylpyrrolidone, Anode material, Lithium-ion batteries, Sol–gel synthesis

Abstract:
The major hindrance to efficient electrocatalytic hydrogen generation from water electrolysis is the sluggish kinetics with corresponding large overvoltage of oxygen evolution reaction. Herein, we report a defective 2D NiCoMoS@Ni(CN)2 core-shell heterostructure derived from Hofmann-type MOF as an efficient and durable high-performance noble metal-free electrocatalyst for hydrazine oxidation reaction (HzOR) in alkaline media. The sluggish oxygen evolution reaction was replaced with a more thermodynamically favourable HzOR, enabling energy-saving electrochemical hydrogen production with 2D NiCoMoS@Ni(CN)2 acting as a bifunctional electrocatalyst for anodic HzOR and cathodic hydrogen generation. Operating at room temperature, the two-electrode electrolyzer delivers 100 mA cm−2 from a cell voltage of just 257 mV, with strong long-term electrochemical durability and nearly 100% Faradaic efficiency for hydrogen evolution in 1.0 M KOH aqueous solution with 0.5 M hydrazine. The density functional theory (DFT) was employed to investigate the origin of catalytic performance and showed that high vacancy creation within the heterointerface endowed NiCoMoS@Ni(CN)2 with favourable functionalities for excellent catalytic performance.

Keywords:
Defect engineering, Core-shell, Electrocatalyst, Hydrazine oxidation, Heterostructure

Abstract:
The measurement and control of the heat transfer of sheet alloys in successive non-isothermal forming cycles is crucial to achieve the desired post-form properties and microstructure, which could not as of yet be realized by using traditional test facilities. In the present research, a novel heat transfer measurement facility was designed to generate and subsequently measure the in-situ heat transfer from a sheet alloy to multi-mediums such as forming tools, air, lubricant and coating. More importantly, the facility was able to use a single sheet alloy sample to perform successive non-isothermal forming cycles, and subsequently obtain high throughput experimental results including the temperature evolution, cooling rate, mechanical properties and microstructures of the alloy. The high throughput in-situ heat transfer measurement facility identified that the cooling rate of AA7075 was 152 °C/s and the mechanical strength was over 530 MPa in the 1st forming cycle. However, it decreased to less than the critical value of 100 °C/s in the successive 10th forming cycle, leading to a low mechanical strength of only 487 MPa. The identified variations that occur in the successive non-isothermal forming cycles would improve the consistency and accuracy of part performance in large-scale manufacturing.

Keywords:
High throughput in-situ measurement,Heat transfer,Successive non-isothermal forming,Sheet alloys,Microstructure

Abstract:
We analyze the three-dimensional (3D) buckling of an elastic filament in a shear flow of a viscous fluid at low Reynolds number and high Péclet number. We apply the Euler-Bernoulli beam (elastica) theoretical model. We show the universal character of the full 3D spectral problem for a small perturbation of a thin filament from a straight position of arbitrary orientation. We use the eigenvalues and eigenfunctions for the linearized elastica equation in the shear plane, found earlier by Liu et al. [Phys. Rev. Fluids 9, 014101 (2024)] with the Chebyshev spectral collocation method, to solve the full 3D eigenproblem. We provide a simple analytic approximation of the eigenfunctions, represented as Gaussian wave packets. As the main result of the paper, we derive the square-root dependence of the eigenfunction wave number on the parameter χ˜ = −η sin 2φ sin2 θ, where

Abstract:
Efficient and sustainable energy conversion depends on the rational design of single-atom catalysts. The control of the active sites at the atomic level is vital for electrocatalytic materials in alkaline and acidic electrolytes. Moreover, fabrication of effective catalysts with a well-defined surface structure results in an in-depth understanding of the catalytic mechanism. Herein, a single atom ruthenium dispersed in nickel-cobalt layered hydroxide (Ru-NiCo LDH) is reported. Through the precise controlling of the atomic dispersion and local coordination environment, Ru-NiCo LDH//Ru-NiCo LDH provides an ultra-low overpotential of 1.45 mV at 10 mA cm−2 for the overall water splitting, which surpasses that of the state-of-the-art Pt/C/RuO2 redox couple. Density functional theory calculations show that Ru-NiCo LDH optimizes hydrogen evolution intermediate adsorption energies and promotes O-O coupling at a Ru-O active site for oxygen evolution, while Ni serves as the water dissociation site for effective water splitting. As a potential model, Ru-NiCo LDH shows enhanced water splitting performance with potential for the development of promising water-alkaline catalysts.

Abstract:
A reliable prediction of the pseudoelastic behavior necessitates the involvement of martensite reorientation in the model. This is important not only under non-proportional loading but in general when the phase transformation proceeds in a localized manner, which results in complex local deformation paths. In this work, an advanced model of pseudoelasticity is developed within the incremental energy minimization framework. A novel enhancement of the model over its original version lies in the formulation of a suitable rate-independent dissipation potential that incorporates the dissipation due to martensitic phase transformation and also due to martensite reorientation, thus yielding an accurate description of the inelastic transformation strain. The finite-element implementation of the model relies on the augmented Lagrangian treatment of the non-smooth incremental energy problem. Thanks to the micromorphic regularization, the related complexities are efficiently handled at the local level, leading to a robust finite-element model. Numerical studies highlight the predictive capabilities of the model. The characteristic mechanical behavior of NiTi tube under non-proportional tension– torsion and the intricate transformation evolution under pure bending are effectively captured by the model. Additionally, a detailed analysis is carried out to elucidate the important role of martensite reorientation in promoting the striations of the phase transformation front.

Keywords:
Shape memory alloys,Phase transformation,Martensite reorientation,Strain localization,Finite-element method

Abstract:
The motivation behind this research is the lack of an underground mining shaft data set in the literature in the form of open access. For this reason, our data set can be used for many research purposes such as shaft inspection, 3D measurements, simultaneous localization and mapping, artificial intelligence, etc. The data collection method incorporates rotated Velodyne VLP-16, Velodyne Ultra Puck VLP-32c, Livox Tele-15, IMU Xsens MTi-30 and Faro Focus 3D. The ground truth data were acquired with a geodetic survey including 15 ground control points and 6 Faro Focus 3D terrestrial laser scanner stations of a total 273,784,932 of 3D measurement points. This data set provides an end-user case study of realistic applications in mobile mapping technology. The goal of this research was to fill the gap in the underground mining data set domain. The result is the first open-access data set for an underground mining shaft (shaft depth −300 m).

Keywords:
LiDAR, IMU, underground shaft mapping, mine mapping

Abstract:
Thermoresponsive shape memory polymers (SMPs) have garnered increasing interest for their exceptional ability to retain a temporary shape and recover the original configuration through temperature changes, making them promising in various applications. The SMP shape change and recovery that happen due to a combination of mechanical loading and appropriate temperatures are related to its particular microstructure. The deformation process leads to the formation and growth of micro-cracks in the SMP structure, whereas the subsequent heating over its glass transition temperature Tg leads to the recovery of its original shape and properties. These processes also affect the SMP microstructure. In addition to the observed macroscopic shape recovery, the healing of micro-crazes and micro-cracks that have nucleated and developed during the loading occurs. Therefore, our study delves into the microscopic aspect, specifically addressing the healing of micro-cracks in the cyclic loading process. The proposed research concerns a thermoplastic polyurethane shape memory polymer (PU-SMP) MM4520 with a Tg of 45 °C. The objective of the study is to investigate the effect of the number of tensile loading-unloading cycles and thermal shape recovery on the evolution of the PU-SMP microstructure. To this end, comprehensive research starting from structural characterization of the initial state and at various stages of the PU-SMP mechanical loading was conducted. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS) and scanning electron microscopy (SEM) were used. Moreover, the shape memory behavior in the thermomechanical loading program was investigated. The obtained average shape fixity value was 99%, while the shape recovery was 92%, which confirmed good shape memory properties of the PU-SMP. Our findings reveal that even during a single loading-unloading tension cycle, crazes and cracks nucleate on the surface of the PU-SMP specimen, whereas the subsequent temperature-induced shape recovery process carried out at the temperature above Tg enables the healing of micro-cracks. Interestingly, the surface of the specimen after three and five loading-unloading cycles did not exhibit crazes and cracks, although some traces of cracks were visible. The traces disappeared after exposing the material to heating at Tg + 20 °C (65 °C) for 30 min. The crack closure phenomenon during deformation, even without heating over Tg, occurred within three and five subsequent cycles of loading-unloading. Notably, in the case of eight loading-unloading cycles, cracks appeared on the surface of the PU-SMP and were healed only after thermal recovery at the particular temperature over Tg. Upon reaching a critical number of cycles, the proper amount of energy required for crack propagation was attained, resulting in wide-open cracks on the material’s surface. It is worth noting that WAXS analysis did not indicate strong signs of typical highly ordered structures in the PU-SMP specimens in their initial state and after the loading history; however, some orientation after the cyclic deformation was observed.

Keywords:
polyurethane shape memory polymer, glass transition temperature, tensile loading cycles, structure analysis, micro-cracks, healing

Abstract:
This study showed that a polylactide (PLA)-based composite filled with nanostructured hydroxyapatite (HAp) and a natural extract from the rhizome of Curcuma longa L. could provide an alternative to commonly used fossil-based plasticsfor food packaging. The incorporation of HAp into the PLA matrix had a positive effect on improving selected properties of the composites; the beneficial effect could be enhanced by introducing a green modifier in the form of an extract. Prior to the fabrication of the composite, the filler was characterized in terms of morphology and composition, and the composite was then fully characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman and Fourier transform infrared spectroscopy (FT-IR), and the mechanical, thermal, thermomechanical, and optical properties were investigated. The proposed material exhibits antioxidant properties against DPPH radicals and antibacterial performance against Escherichia coli (E. coli). The results showed that the nanocomposite has the highest antioxidant and antibacterial properties for 10 wt% HAp with an average diameter of rod-shaped structures below 100 nm. In addition, the introduction of turmeric extract had a positive effect on the tensile strength of the nanocomposites containing 1 and 5% HAp. As the resulting material adsorbs light in a specific wavelength range, it can be used in the medical sector, food-packaging, or coatings.

Keywords:
polylactide, hydroxyapatite, turmeric extract, curcumin extract, green composite

Abstract:
Dissemination of food-borne L. monocytogenes in the host relies on internalin-mediated invasion, but the underlying invasion strategies remain elusive. Here we use live-cell microscopy to follow single cell interactions between individual human cells and L. monocytogenes and elucidate mechanisms associated with internalin B (InlB)-mediated invasion. We demonstrate that whilst a replicative invasion of nonphagocytic cells is a rare event even at high multiplicities of invasion, L. monocytogenes overcomes this by utilising a strategy relaying on PrfA-mediated ActA-based aggregation. We show that L. monocytogenes forms aggregates in extracellular host cell environment, which promote approximately 5-fold more host cell adhesions than the non-aggregating actA-ΔC mutant (which lacks the C-terminus coding region), with the adhering bacteria inducing 3-fold more intracellular invasions. Aggregation is associated with robust MET tyrosine kinase receptor clustering in the host cells, a hallmark of InlB-mediated invasion, something not observed with the actA-ΔC mutant. Finally, we show via RNA-seq analyses that aggregation involves a global adaptive response to host cell environment (including iron depletion), resulting in metabolic changes in L. monocytogenes and upregulation of the PrfA virulence regulon. Overall, our analyses provide new mechanistic insights into internalin-mediated host-pathogen interactions of L. monocytogenes.

Keywords:
Listeria monocytogenes, host-pathogen interactions, aggregation, PrfA regulon, livecell microscopy

Abstract:
We explore methods to generate quantum coherence through unitary evolutions, by introducing and studying the coherence generating capacity of Hamiltonians. This quantity is defined as the maximum derivative of coherence that can be achieved by a Hamiltonian. By adopting the relative entropy of coherence as our figure of merit, we evaluate the maximal coherence generating capacity with the constraint of a bounded Hilbert- Schmidt norm for the Hamiltonian. Our investigation yields closed-form expressions for both Hamiltonians and quantum states that induce the maximal derivative of coherence under these conditions. Specifically, for qubit systems, we solve this problem comprehensively for any given Hamiltonian, identifying the quantum states that lead to the largest coherence derivative induced by the Hamiltonian. Our investigation enables a precise identification of conditions under which quantum coherence is optimally enhanced, offering valuable insights for the manipulation and control of quantum coherence in quantum systems.

Keywords:
Resource Generation, Quantum Coherence, Quantum Control

Abstract:
In this paper, 20 µm and 40 µm thick aluminide coatings were deposited on MAR-M247 nickel-based superalloy through the chemical vapor deposition (CVD) process in a hydrogen protective atmosphere for 4 h and 12 h, respectively, at a temperature of 1040 °C and an internal pressure of 150 mbar. The effect of aluminide coating thickness on the high-temperature performance of the MAR-M247 nickel-based superalloy was examined during a fatigue test at 900 °C. After high-temperature testing, the specimens were subjected to fractographic analysis to reveal the damage mechanisms. No significant effect of coating thickness was found since the material exhibited a similar service life throughout the fatigue test when subjected to the same stress amplitude. One should stress that the coating remained well adhered after specimen fracture, confirming its effectiveness in protecting the material against high-temperature oxidation.

Keywords:
fatigue, aluminide coatings, nickel alloys , high-temperature performance

Abstract:
Hierarchical nanostructures fabricate by electrospinning in combination with light-responsive agents offer promising scenarios for developing novel activable antibacterial interfaces. This study introduces an innovative antibacterial face mask developed from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers integrated with indocyanine green (ICG), targeting the urgent need for effective antimicrobial protection for community health workers. The research focuses on fabricating and characterizing this nanofibrous material, evaluating the mask's mechanical and chemical properties, investigating its particle filtration, and assessing antibacterial efficacy under photothermal conditions for reactive oxygen species (ROS) generation. The PHBV/ICG nanofibers are produced using an electrospinning process, and the nanofibrous construct's morphology, structure, and photothermal response are investigated. The antibacterial efficacy of the nanofibers is tested, and substantial bacterial inactivation under both near-infrared (NIR) and solar irradiation is demonstrated due to the photothermal response of the nanofibers. The material's photothermal response is further analyzed under cyclic irradiation to simulate real-world conditions, confirming its durability and consistency. This study highlights the synergistic impact of PHBV and ICG in enhancing antibacterial activity, presenting a biocompatible and environmentally friendly solution. These findings offer a promising path for developing innovative face masks that contribute significantly to the field of antibacterial materials and solve critical public health challenges.

Abstract:
Fast and high-quality ultrasound imaging allows to increase the effectiveness of detecting tissue changes at the initial stage of disease. The aim of the study was to assess the quality of ultrasound imaging using mutually
orthogonal, complementary Golay coded sequences (MOCGCS). Two 16-bits MOCGCS sets were implemented in the Verasonics Vantage™ scanner. Echoes from a perfect reflector, a custom-made nylon wire phantom,a tissue-mimicking phantom, and in-vivo scans of abdominal aorta and common carotid artery were recorded.Three parameters of the detected MOCGCS echoes: signal-to-noise ratio (SNR), side-lobe level (SLL), and axial resolution were evaluated and compared to the same parameters of the echoes recorded using standard
complementary Golay sequences (CGS) and a short, one sine cycle pulse. The results revealed that MOCGCS
transmission maintained comparable echo quality metrics (SNR, SLL, and axial resolution) compared to CGS
and short pulses. Notably, both MOCGCS and CGS offered similar SNR improvements (5 dB–9 dB) in compar-ison to the short pulse for wires placed at depths up to 8 cm. Analysis of axial resolution, estimated at the full width at half maximum level, revealed near-identical values for all transmitted signals (0.17 μs for MOCGCS,0.16 μs for CGS, and 0.18 μs for short pulse). MOCGCS implementation in ultrasound imaging offers the po-tential to significantly reduce image reconstruction time while maintaining image quality comparable to CGS sequences. In the experimental study we have shown that MOCGCS offers advantages over conventional CGS by enabling two times faster data acquisition and image reconstruction without compromising image quality.

Keywords:
coded excitation, Golay codes, synthetic aperture

Abstract:
Metal-ceramic composites by their nature have thermal residual stresses at the micro-level, which can compromise the integrity of structural elements made from these materials. The evaluation of thermal residual stresses is therefore of continuing research interest both experimentally and by modeling. In this study, two functionally graded aluminum alloy matrix composites, AlSi12/Al2O3 and AlSi12/SiC, each consisting of three composite layers with a stepwise gradient of ceramic content (10, 20, 30 vol%), were produced by powder metallurgy. Thermal residual stresses in the AlSi12 matrix and the ceramic reinforcement of the ungraded and graded composites were measured by neutron diffraction. Based on the X-ray micro-computed tomography (micro-XCT) images of the actual microstructure, a series of finite element models were developed to simulate the thermal residual stresses in the AlSi12 matrix and the reinforcing ceramics Al2O3 and SiC. The accuracy of the numerical predictions is high for all cases considered, with a difference of less than 5 % from the neutron diffraction measurements. It is shown numerically and validated by neutron diffraction data that the average residual stresses in the graded AlSi12/Al2O3 and AlSi12/SiC composites are lower than in the corresponding ungraded composites, which may be advantageous for engineering applications.

Keywords:
Finite element modeling,Micro-XCT,Thermal residual stress,Hot pressing,Aluminum matrix composites

Abstract:
Direct Metal Laser Sintered Haynes 282 specimens as well as wrought ones were subjected to high-temperature exposure at 1000 °C for 100h in air to compare their oxidation behaviour. The specimens were removed from the furnace after 1h, 5h, 25h, 50h and 100h to reveal and study oxidation mechanisms through morphological and cross-sectional examination by using scanning electron microscopy with energy dispersive spectroscopy attachment and X-ray diffraction. Microstructural studies revealed that the oxidation kinetics, determined by changes in thickness scale and depth of aluminium diffusion zone, were mainly driven by the formation of Cr2O3 for the wrought material, and TiO2 for DMLS one. The wrought material was characterized by the oxidation rate equal to 0.96 and followed the logarithmic law. On the other hand, DMLS-manufactured Haynes 282 exhibited oxidation rate of 0.90 and follows the linear law for the thickness scale considerations. However, when the depth of aluminium diffusion was investigated, it had an oxidation rate of 0.87 and followed cubic law.

Abstract:
The resource theory of imaginarity studies the operational value of imaginary parts in quantum states, operations, and measurements. Here we introduce and study the distillation and conversion of imaginarity in distributed scenario. This arises naturally in bipartite systems where both parties work together to generate the maximum possible imaginarity on one of the subsystems. We give exact solutions to this problem for general qubit states and pure states of arbitrary dimension. We present a scenario that demonstrates the operational advantage of imaginarity: the discrimination of quantum channels without the aid of an ancillary system. We then link this scenario to local operations and classical communications(LOCC) discrimination of bipartite states. We experimentally demonstrate the relevant assisted distillation protocol, and show the usefulness of imaginarity in the aforementioned two tasks.

Abstract:
The article presents the diagnostic results on surface-hardened industrial concrete floors. Selected examples of floors showcased premature damage to surface layers, characterized by intense dusting, delamination, and local spalling, while the structural system remained unaffected. Quantitative petrographic analysis of concrete was applied to core specimens from the floors, involving the examination of digital images from a polarizing optical microscope and a scanning electron microscope. The hardening compound and powdered specimens of the cement matrix were characterized using differential thermal analysis and X-ray diffraction. A multiple microindentation method was employed to assess local variations in mechanical properties. Concrete cross-section analysis revealed areas with a non-uniform distribution of air voids, identified regions exhibiting increased porosity, highlighted areas of cracking in the concrete, indicated local variability in the phase composition of cement hydration products, and pointed out the presence of carbonated areas. The causes of the damage were discussed based on these findings,. The crucial role of quantitative petrographic analysis in diagnosing premature surface damage to industrial floors was demonstrated.

Keywords:
concrete, delamination, quantitative microscopy, porosity, industrial floors, dusting, surface hardening

Abstract:
The most commonly applied way of teaching students to convey the foundations of human anatomy and physiology involves textbooks and lectures. This way of transmitting knowledge causes difficulties for students, especially in the context of three-dimensional imaging of organ structures, and as a consequence translates into difficulties with imagining them. Even despite the rapid uptake of knowledge dissemination provided by online materials, including courses and webinars, there is a clear need for learning programs featuring first-hand immersive experiences tailored to suit individual study paces. In this paper, we present an approach to enhance a classical study program by combining multi-modality data and representing them in a Mixed Reality (MR)-based environment. The advantages of the proposed approach have been proven by the conducted investigation of the relationship between atrial anatomy, its electrophysiological characteristics, and resulting P wave morphology on the electrocardiogram (ECG). Another part of the paper focuses on the role of the sinoatrial node in ECG formation, while the MR-based visualization of combined micro-computed tomography (micro-CT) data with non-invasive CineECG imaging demonstrates the educational application of these advanced technologies for teaching cardiac anatomy and ECG correlations.

Keywords:
mixed reality, CineECG, micro-CT, P wave, ECG imaging

Abstract:
Arm-Z to koncepcja hiperredundantnego manipulatora robotycznego opartego na sekwencji szeregowo połączonych identycznych modułów. Każdy moduł ma tylko jeden stopień swobody (1-DOF) – skręt względem poprzedniego. Moduły systemu Arm-Z mogą być masowo produkowane i łatwo wymieniane w przypadku awarii. Sterowanie Arm-Z jest stosunkowo trudne, dlatego zwykle wymaga stosowania metod inteligencji obliczeniowej. W artykule przedstawiono kilka koncepcji kinetycznych obiektów małej architektury opartych na Arm-Z: spiralną kolumnę o regulowanej wysokości, system nadążania słonecznego, kinetyczną rzeźbę bioniczną i kinetyczny zraszacz/fontannę. Prezentowane koncepcje są zasadniczo nisko-technologiczne (“low-tech”). W każdym przypadku moduł bazowy jest przymocowany do podstawy (podłoża). Dla prostoty napęd jest przykładany bezpośrednio do pierwszego modułu, a następnie przenoszony za pomocą wewnętrznych przekładni na kolejne moduły. Każdy moduł jest wyposażony w zestaw cylindrycznych i stożkowych kół zębatych z zębami prostymi o profilu spiralnym (do połączeń miedzy modułami).

Keywords:
Arm-Z, hiperredundancja, manipulator, mała architektura, systemy modularne

Abstract:
Development and step-by-step characterizations of a novel cationic thiophene based copolymer (P1buP), including ionic phosphonium salt and dye-tetraphenylporphyrin (TPP) moiety in side chains, with an iconic property of solubility in a wide range of polar solvents is reported. Synthesized by using simple, low-cost, and straightforward procedures, the material is used to fabricate completely halogen-free (i.e., from ethanol) ternary organic solar cells (OSCs), in the presence of an alcohol-soluble ionic 3,4-dialkoxythiophene based homopolymer (P2buP) and a serinol-fullerene derivative (C60-Ser). Indeed, thanks to co-sensitization techniques, where multiple dyes harvest different parts of the solar spectrum, the power conversion efficiency of the best final device dramatically increases up to nearly 5.0%, as the light absorption is usually optimized. Additionally, since the use of a cathode interlayer in OSCs also plays a pivotal role in electron extraction and device stability, a possible application of the ionic TPP material as the interfacial layer is also investigated. Furthermore, to improve and optimize the best performing device, a successful post-metalation with Zn of the porphyrin core is carried out, and a ternary OSC (P1buP:P2buP:C60-Ser = 0.33:0.67:1 w/w) is fabricated, resulting in a photoconversion efficiency (PCE) of ∼6.0%.

Keywords:
Ionic dye-tetraphenylporphyrin, Co-sensitization, Ternary OSCs, Cathode interlayers, Halogen-free deposition

Abstract:
This paper provides a comprehensive overview of the influence of 1-Butyl-1-Methylpyrrolidinium Trifluoromethanesulfonate (BMPyrrOTf)-ionic liquid on a new polymer electrolyte where Polyethylene oxide (PEO) as host and ammonium iodide (NH4I) as salt. These IL-doped solid polymer electrolyte were prepared using solution cast technique. Various characterisation techniques have been utilized to evaluate the qualitative and quantitative estimation of polymer electrolyte like Polarized microscopy (POM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Linear sweep voltammetry (LSV), Ionic transference no. (tion) and Impedance spectroscopy. Doping IL increases conductivity and highest achieve at 8 wt% of BMPyrrOTF with conductivity value reaches upto 4.15 × 10–5 S/cm at. Using Wagner’s polarization method, Ionic transference measurement support ionic conduction while stable potential window has further affirmed good electrochemical stability of films. The highest conducting IL-enriched polymer electrolyte sandwiched low-cost dye-sensitized solar cells (DSSCs) and electric double layer capacitors (EDLCs) have been developed, and their performance is conveniently appropriate.

Abstract:
Molybdenum sulfide–oxide (MoS2, MS) emerges as the prime electrocatalyst candidate demonstrating hydrogen evolution reaction (HER) activity comparable to platinum (Pt). This study presents a facile electrochemical approach for fabricating a hybrid copper (Cu)/MoS2 (CMS) nanos- tructure thin-film electrocatalyst directly onto nickel foam (NF) without a binder or template. The synthesized CMS nanostructures were characterized utilizing energy-ispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical methods. The XRD result revealed that the Cu metal coating on MS results in the creation of an extremely crys-talline CMS nanostructure with a well-defined interface. The hybrid nanostructures demonstrated
higher hydrogen production, attributed to the synergistic interplay of morphology and electron dis-tribution at the interface. The nanostructures displayed a significantly low overpotential of −149 mV at 10 mA cm−2 and a Tafel slope of 117 mV dec−1, indicating enhanced catalytic activity compared to pristine MoS2.This research underscores the significant enhancement of the HER performance and
conductivity achieved by CMS, showcasing its potential applications in renewable energy.

Keywords:
electrodeposition, hydrogen evolution reactions, catalytic activity, Cu/MoS2 nanostructures

Abstract:
The ability of piezoelectric materials to convert mechanical energy into electric energy and vice versa has made them desirable in the wide range of applications that oscillate from medicine to the energetics industry. Their implementation in optical communication is often connected with the modulation or other manipulations of the light signals. In this article, the recent advancements in the field of piezoelectrics-based devices and their promising benefits in optical communication are explored. The application of piezoelectrics-based devices in optical communication allows dynamic control, modulation, and manipulation of optical signals that lead to a more reliable transmission. It turns out that a combination of artificial-intelligence-based algorithms with piezoelectrics can enhance the performance of these devices, including optimization of piezoelectric modulation, adaptive signal processing, control of optical components, and increase the level of energy efficiency. It can enhance signal quality, mitigate interference, and reduce noise-connected issues. Moreover, this technological fusion can increase the security of optical communication systems. Finally, the potential future research lines are determined.

Abstract:
Functional antibacterial textiles fabricated from a hybrid of organic waste-derived and bio-inspired materials offer sustainable solutions for preventing microbial infections. In this work, we developed a novel antibacterial textile created through the valorization of spent coffee grounds (SCG). Electrospinning and electrospraying techniques were employed to integrate the biowaste within a polymeric nanofiber matrix, ensuring uniform particle distribution and providing structural support for enhanced applicability. Modification with polydopamine (PDA) significantly enhanced the textile's photothermal performance. Specific attention was paid to understanding the relation between temperature change and key variables, including the surrounding liquid volume, textile layer stacking, and applied laser power. Developed platforms demonstrated excellent photothermal stability. While the SCG-based textile demonstrated exceptional biocompatibility, the PDA-modified textile effectively eradicated Staphylococcus aureus (S. aureus) under near-infrared (NIR) irradiation. The developed textiles in our work demonstrate a dynamic balance between biocompatibility and on-demand antibacterial functionality, offering adaptable solutions in accordance with the desired application.

Keywords:
Organic waste valorization, Spent coffee grounds, Micro-nanostructured textiles, Bio-inspired photothermal agents, Polydopamine, Antibacterial textiles

Abstract:
Emergency bridges are used to restore the lifeline of damaged bridges after disasters. However, the design specification of existing emergency bridges do not afford rapid bridging. Therefore, a trial deployable bridge (Scissors Bridge) using a scissors structure that folds compactly has been experimentally produced. But, the assembly process for the bridge has not been considered and there are no practical design examples or design methods for scissors bridges. In this paper, as for existing bridges, we established a design method of scissors bridges when considering the live load. In addition, a general-purpose member cross-sectional dimension optimization method, aimed at minimizing weight, was developed and proposed. Considering the problem of insufficient strength of the scissors bridge, the optimum reinforcing pattern and its cross-sectional dimensions were determined through two methods of reinforcement and optimization of the cross-sectional dimension of the member. Finally, a trial of practical design calculation was performed using the results of the study to determine whether a scissors bridge satisfying the standard of the Specifications for Highway Bridges can be designed.

Keywords:
scissors structure,deployable bridge,stress analysis

Abstract:
In the article, investigation is carried out at the second stage of aluminizing, when a consistent substance containing aluminium powder (the first option) or graphite powder and aluminium powder (the second option) is applied to the surface that has undergone aluminizing at the first stage, before further electrospark alloying with an aluminium electrode, and, regardless of the drying of the consistent substance, the aluminizing process is carried out at a discharge energy of 0.52–2.6 J and a productivity of 1.0–2.0 cm2/min, while the discharge energy and productivity are chosen such that the surface roughness decreases by ≅ 3–4 times. At the second stage aluminizing for both options, when using a consistent substance that contains aluminium powder or aluminium powder and graphite powder, the microhardness of the ‘white layer’ and the diffusion zone are increased (to a greater degree when graphite is present in the consistent substance), the surface roughness is decreased, and the integrity of the coating is of 100%. Before practical implementation, it is recommended to carry out the aluminizing process according to the first option at the discharge energy Wp = 4.6–6.8 J, using a consistent substance containing aluminium powder and graphite powder at the second stage.

Keywords:
electrospark alloying, aluminizing, productivity, surface layer, quality, structure, roughness, microhardness, thickness of the white layer, coating continuity

Abstract:
We consider online learning in the model where a learning algorithm can access the class only via the consistent oracle—an oracle, that, at any moment, can give a function from the class that agrees with all examples seen so far. This model was recently considered by Assos et al. (COLT’23). It is motivated by the fact that standard methods of online learning rely on computing the Littlestone dimension of subclasses, a computationally intractable problem. Assos et al. gave an online learning algorithm in this model that makes at most Cd mistakes on classes of Littlestone dimension d, for some absolute unspecified constant C > 0. We give a novel algorithm that makes at most O(256d) mistakes. Our proof is significantly simpler and uses only very basic properties of the Littlestone dimension. We also show that there exists no algorithm in this model that makes less than 3d mistakes. Our algorithm (as well as the algorithm of Assos et al.) solves an open problem by Hasrati and Ben-David (ALT’23). Namely, it demonstrates that every class of finite Littlestone dimension with recursively enumerable representation admits a computable online learner (that may be undefined on unrealizable samples).

Keywords:
Online learning, consistent oracle, Littlestone dimension

Abstract:
We show that the Soft Actor-Critic Reinforced Learning algorithm is able to find efficient motion patterns for a hyper-redundant robot consisting of 6 identical modules connected in a chain like fashion. The control is done by applying relative angular velocities between the modules. Analogous system has been studied before in the context of a robotic trunk-like manipulator.

Keywords:
Reinforced Learning, Robotic Locomotion, Hyperreduntant Modular Manipulator, Arm-Z, Extremely Modular System

Abstract:
The necessity of tailoring more environmentally friendly materials has prompted researchers and practitioners to explore new and more sustainable components for cement-based mixtures. Some of these materials are in their natural state and they can also be used to improve the mechanical performances of cementitious composites. Sheep wool, which is nowadays considered a special waste, can substitute some polymeric fibres to increase the fracture toughness. However, in alkaline environment, wool fibres tend to degrade within a few days after casting, so fibres can lose the reinforcement function of concrete and mortars due to long term durability issues. A series of tests have been performed with the aim of examining the microstructure and measuring the mechanical properties of wool-reinforced pastes made with various types of cement. By linking the results of microstructural analyses with those of the mechanical tests, it is possible to argue that the lower the pH of the paste the larger the efficiency of wool fibres.

Keywords:
wool-reinforced paste, microstructure analyses, residual strength, degradation, sustainability, eco-friendly material

Abstract:
Multiphase metal matrix composites are used in modern industries like energy, aerospace, and automotive. The materials are used in severe loading conditions like impact loads or thermal shocks. The presentation concerns a data-driven model of an interpenetrated composite. The geometry of the material phases is obtained using CT scanning. Further details, namely, the distribution of voids and inclusions are found with the scanning as well. Based on CT scans the 3D finite element and peridynamics models are derived from. Former analyses [1, 2] showed the importance of the existence of an interface zone in multiphase composites. In the current presentation, the diffusion-based mechanism of forming the interphase zone is shown. A constitutive law evaluated in [3] is considered. The constitutive law for the cohesive zone was obtained using molecular dynamics simulations. The effects of the MD-based law on mesoscale samples are presented. Acknowledgment: Grant from National Science Committee (PL) UMO-2019/33/B/ST8/01263; Polish National Agency for Academic Exchange (NAWA) [BPN/ULM/2021/1/00115/U/DRAFT/00001] Calculations: PL-GRID National Facilities: CYFRONET, Krakow, ICM at the University of Warsaw, TASK, Gdansk, Poland, and LUMI in Kajaani, Finland. References: [1] Felten, F., Schneider, G., and Sadowski T. Estimation of R-curve in WC/Co cermet by CT test. Int. J. Refract. Hard. Met., Vol. 26, pp. 55-60, 2008. [2] Postek, E. and Sadowski, T. Qualitative comparison of dynamic compressive pressure load and impact of WC/Co composite. Int. J. Refract. Hard. Met., Vol. 77, pp. 68-81, 2018. [3] Tahani, M., Postek, E., and Sadowski T., Investigating the Influence of Diffusion on the Cohesive ZoneModel of the SiC/Al Composite Interface, Molecules, Vol.28, No.19, pp. 6757-1-6757-19, 2023.

Keywords:
Multiphase materials, Diffusion, Consitituve law, Molecular dynamics

Abstract:
Extremely Modular System (EMS for short) is a relatively new concept introduced by the
author a few years ago. It represents a new approach to the design of engineering
structures and architectural objects where assembly of congruent units allows for the
creation of free-form shapes.
The main difference from the traditional modular systems used in engineering, is the
emphasis of the minimal diversity of types of modules, ideally - just one. This is why these
system are extremely modular.

These are six basic advantages of EMSs:
1. Economical - as they are suitable for mass fabrication, thus lowering the cost so they
can be broadly applied;
2. Functional - as they allow for reconfiguration, expansion, reduction;
3. Robust - since every module which failed can be easily replaced with an identical but functional one;
4. Discrete - as they are suitable for intelligent mathematical modeling, and their configurations can be subjected to discrete (multi-objective) optimization using efficient search algorithms;
5. Uniform - this feature is advantageous for rapid deployment and automated assembly.
6. Sustainable - as the entire modules can be reused.

One of the most advantageous areas for implementation of EMSs are deployable structures.
Moreover, it is crucial that the individual modules and entire structure are rigid.
This paper presents folding mechanisms for two selected EMSs: Pipe-Z - a parametric system
comprised of one type of module allowing for creation of three-dimensional knots, and Truss-Z -
a modular system for creating free-form ramps and ramp networks among any number of
terminals.

Keywords:
Extremely Modular System, Deployable Structure, Free-form, Pipe-Z, Truss-Z

Abstract:
Multiple bifurcations due to symmetry are often encountered when analyzing nonlinear motifs of nano-mechanics or structures with axial multiple symmetry. The location of multiple bifurcation points and bifurcation path tracing become problems in numerical analysis. In this paper, as a solution to this problem, the a priori information of group-theoretic bifurcation theory is applied. By utilizing the irreducible representation of the dihedral group, we propose to represent the initial imperfection vectors according to the difference in symmetry of the structural system. A part of the tangent stiffness matrix is corrected by coordinate transformations, and
the modified stiffness method is proposed to separate the multiple bifurcation points to a single point in the direction of the bifurcation path. As a numerical analysis example, a bifurcation analysis of a fullerene structure is performed to demonstrate the feasibility of the presented method.

Keywords:
Graph-theory, Bifurcation, Imperfection, Fulerene, Dihedral group

Abstract:
This contribution considers the problem of topology optimization of modular structures. A bionic trunk-like robotic “Arm-Z” manipulator is considered. The manipulator is modular, that is, it is composed of a sequence of identical modules. In geometric terms, each module is essentially an obliquely cut section of an elliptical pipe, so in the cutting plane it forms a circle. With respect to the previous module, it has a single degree of freedom: the relative twist. Therefore, the total number of the degrees of freedom of the entire manipulator equals the number of its modules. Such a manipulator belongs to the family of Extremely Modular Systems. The advantages of such systems are the economization (due to the possible mass production of modules) and robustness (replacement of a failed module instead of a complex repair).

Keywords:
Topology optimization, Modular manipulator, Multiple loadings, Geometric transformations, Kinematics, Stress constraints.

Abstract:
The aim of this research was to investigate an effect of low temperature on the mechanical properties and microstructure of 6061-T6 aluminium alloy (AA6061-T6) subjected to dynamic loading. The specimens were subjected to dynamic compression at a low temperature of -80°C in a range of strain rates from 1.25×103 1/s to 3.4 ×103 1/s to compare their mechanical responses. The deformation mechanisms were analysed through EBSD observations during which dynamic recovery, was found as the dominant one. Furthermore, microstructural analysis indicated that deformation under high strain rate conditions and temperature of -80°C enables to keep the constant initial grain size of the material after the loading applied.

Keywords:
Split Hopkinson Pressure Bar (SHPB), low temperature, AA6061, microstructure, EBSD

Abstract:
The Laser Powder Bed Fusion Melting (LPBF-M) method was used to additively manufacture stainless steel 316L tubes in three different orientations. The yield surface approach was implemented to assess the variation of mechanical properties within the as-built specimens. Yield surfaces were determined for each build orientation based on the definition of yield stress for 0.005% plastic offset strain. The initial yield surfaces obtained for the as-built material exhibit anisotropic behaviour, possibly resulting from the preferred grain orientation developed during LPBF-M processing.

Abstract:
There have been considered the coating structure modification after electrospark alloying (ESA) by the Mo-electrode using a paste with carbon nanotubes. It was showed that the regimes and composition of the paste influenced the microstructure, continuity, roughness, and hardness of the coatings. The microstructures after the ESA of the Armco iron were studied. The use of higher discharge energy in ESA leads to an increase in surface roughness, coating thickness, and coating continuity. The use of higher discharge energy during ESA results in an increase in surface roughness, coating thickness, and coating continuity. The microstructures reveal nanoscale phases from 40 to 60 nm, which are evenly distributed in the coatings. The addition of ARKEMA nanotubes increases the hardness to 608 HV. The results of local X-ray diffraction analysis showed that carbon is concentrated on the surface, while molybdenum is distributed homogeneously in the coating. The addition of nanotubes to the paste before ESA improves hardness and continuity. The effect of nanotubes on the structure and properties of coatings is positive.

Keywords:
X-ray diffraction, Nanostructures, Nanotubes

Abstract:
This paper presents an analysis of various technologies, including such as aluminization, cementation, nitriding, and nitrocementation, to increase the quality parameters of surface layers of parts, performed by electrospark alloying (ESA) and by additional saturation of surfaces with alloying elements from special technological environments (STE). During aluminization, the thickness of the "white" layer and the diffusion zone, as well as the microhardness, coating continuity and roughness of the surface increased as the discharge energy (Wp) increased. The layer consists of iron-aluminium intermetallics and free aluminium. It has been proposed to perform the ESA process with the same electrode (aluminium), but at lower energies, in order to reduce the surface roughness and obtain continuous coatings. The comparative study of the parameters of the quality of the layers after the traditional cementation - ESA with carbon electrode (CESA) and after the proposed one has shown that after the treatment of the surface with the use of the proposed technology, the roughness of the surface decreases. Simultaneously, the continuity of the doped layer increases up to 100%, the depth of the carbon diffusion zone increases up to 80 µm, and the microhardness and "white" layer thickness increase to 9932 MPa and 230 µm, respectively. The analysis of the structure-forming characteristics of the surface layers of carbon steel after ESA nitriding and nitrocarburising using STE has shown that the layer structures obtained consist of the following three areas, such as the non-etchable "white" layer, the modified diffusion zone and the substrate. Thickness, microhardness of the coating zones, integrity of the "white" layer, and surface roughness also increase as the discharge energy increases.

Keywords:
Electrodes, Hardness, Metallurgy, Surface hardening

Abstract:
This contribution presents a semi-active control technique intended for mitigation of structural vibrations. The control law is derived in a repeated trial-and-error interaction between the control agent and a simulated environment. The experience-based training approach is used which is the defining feature of the machine learning techniques of reinforcement learning (RL), implemented here using the framework provided by Deep Q Learning (DQN). The involved artificial neural network not only determines the control action, but additionally identifies structural damages, which is a nontrivial task due to the nonlinearity of the control. This requires a specific multi-head architecture, which allows the network to be damage-aware, and a specific training procedure, where the memory pool preserved for the RL stage of experience replay is populated with not only the observations, control actions, and rewards, but also with the momentary status of structural damage. Such an approach can be used to explicitly promote the damage-awareness of the control agent. The proposed technique is tested and verified in a numerical example of a shear-type building model subjected to a random seismic-type excitation. A tuned mass damper (TMD) with a controllable level of viscous damping is used to implement the semi-active actuation, and the optimally tuned classical TMD provides the reference response.

Keywords:
semi-active control, tuned mass damper (TMD), reinforcement learning, damage identification

Abstract:
W artykule autorzy omawiają duże modele językowe (ang. Large Language Models, LLMs) w kontekście zagrożeń bezpieczeństwa wynikających z funkcji i dostępności tych modeli. Mimo że pod względem zastosowań LLMs wydają się podobne do wyszukiwarek internetowych, to generują nowe zagrożenia związane z dostarczaniem przez nie przestępcy i terroryście podstawowych umiejętności analitycznych i programistycznych. Autorzy dowodzą, że dostępne modele językowe nie tylko zmniejszają bariery finansowe dla rożnych działań przestępczych, lecz także obniżają poziom wiedzy specjalistycznej i zaangażowania wymagany od jednostek lub małych grup do popełniania przestępstw, w tym aktów terrorystycznych. Z drugiej strony możliwości tych modeli mogą wykorzystać również organy ścigania, aby być przygotowanymi na pojawiające się zagrożenia.

Keywords:
Large Language Models, bezpieczeństwo, cyberprzestępczość, terroryzm dżihadystyczny, sztuczna inteligencja

Abstract:
Over the past 20 years, there has been a dramatic increase in the incidence of various cancers. The increased detection of various malignancies and their effective treatment requires the search for new approaches in anti-cancer therapy. One option is the use of nanomaterials and nanocomposites based on them to form a platform for simultaneous imaging, such as by nuclear magnetic resonance, and treatment by local drug release and temperature elevation directly in tumor tissues [1]. Here, we present results on the colloidal suspension based on superparamagnetic iron-oxide-based nanoparticles and hydroxyapatites as the matrix for the local anticancer drug release. The studies were focused on the optimization of the synthesis experimental composition, characterization of obtained material, and stability in aqueous solutions like PBS to be used in magnetic hyperthermia to generate heat locally and enhance the drug delivery. Core-shell particles were synthesized using a two-step wet co-precipitation method and stabilized with biocompatible organic molecules to produce stable colloidal suspension [2,3]. The heat generation effectiveness was determined using magnetic hyperthermia (MH), where the conditions to reach therapeutic temperature of the suspension in the constant and pulsed amplitude of alternating magnetic field (AMF) were optimized.