The flexibility of dose and dosage forms makes 3D printing a very interesting tool for personalized medicine, with fused deposition modeling being the most promising and intensively developed method. In our research, we analyzed how... more
The flexibility of dose and dosage forms makes 3D printing a very interesting tool for personalized medicine, with fused deposition modeling being the most promising and intensively developed method. In our research, we analyzed how various types of disintegrants and drug loading in poly(vinyl alcohol)-based filaments affect their mechanical properties and printability. We also assessed the effect of drug dosage and tablet spatial structure on the dissolution profiles. Given that the development of a method that allows the production of dosage forms with different properties from a single drug-loaded filament is desirable, we developed a method of printing ketoprofen tablets with different dose and dissolution profiles from a single feedstock filament. We optimized the filament preparation by hot-melt extrusion and characterized them. Then, we printed single, bi-, and tri-layer tablets varying with dose, infill density, internal structure, and composition. We analyzed the reproducib...
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Bone trabecular structure can be characterized as a connected network of mineral bars and plates with unique mechanical properties. Standard methods of producing bone-like structures based on periodic structures or foams have same... more
Bone trabecular structure can be characterized as a connected network of mineral bars and plates with unique mechanical properties. Standard methods of producing bone-like structures based on periodic structures or foams have same limitations. The organization of the trabecular bone (meso scale) is adapted to the values of stresses and strains affecting the skeletal system. To simulate bone-like structure, the methodology of generating stochastic structure based on hyperuniform spatial points distribution is proposed. Statistical analysis of generated structure shows the possibility to generate clouds of points in wide range of random close packing density, up to 59.52%. Points connected by Voronoi tessellation produce to unique porous topology with no closed-cells and with wide range of connectivity. Manufacturing of a generated structure is only limited by used technique. The proposed algorithm was developed regardless of the manufacturing technique, however, same examples of the s...
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The paper deals with investigation on directional variations of mechanical response in 3D printed models of human trabecular bone. Sample of trabecular bone tissue was resected from human donor and 3D model was obtained by X-ray computed... more
The paper deals with investigation on directional variations of mechanical response in 3D printed models of human trabecular bone. Sample of trabecular bone tissue was resected from human donor and 3D model was obtained by X-ray computed tomography. Then a series of cubical samples was prepared by additive manufacturing technique and tested by uniaxial compression loading mode. Mechanical response was compared in nine different combinations of direction of 3D printing and loading direction. The results show neglectible influence on the deformation response in elastic region (stiffness) and significant changes of the behaviour in plastic region (stress and strain at yield point, strain at full collapse).
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The aim of this work was to investigate of biocompatibility of polymeric implants modified with silver nanoparticles (AgNPs). Middle ear prostheses (otoimplants) made of the (poly)acrylonitrile butadiene styrene (ABS) and ABS modified... more
The aim of this work was to investigate of biocompatibility of polymeric implants modified with silver nanoparticles (AgNPs). Middle ear prostheses (otoimplants) made of the (poly)acrylonitrile butadiene styrene (ABS) and ABS modified with silver nanoparticles were prepared through extrusion and injection moulding process. The obtained prostheses were characterized by SEM-EDX, micro-CT and mechanical tests, confirming their proper shape, good AgNPs homogenization and mechanical parameters stability. The biocompatibility of the implants was evaluated in vivo on rats, after 4, 12, 24 and 48 weeks of implantation. The tissue-healing process and cytotoxicity of the implants were evaluated on the basis of microscopic observations of the materials morphology after histochemical staining with cytochrome c oxidase (OCC) and acid phosphatase (AP), as well as via micro-tomography (ex vivo). The in vivo studies confirmed biocompatibility of the implants in the surrounding tissue environment. B...
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ABSTRACT We present an original method for the determination of residual stresses in plastically deformed polycrystalline material (1, 2). The advantage of our method is that the anisotropy of residual stress field can be determined.... more
ABSTRACT We present an original method for the determination of residual stresses in plastically deformed polycrystalline material (1, 2). The advantage of our method is that the anisotropy of residual stress field can be determined. Moreover, the principles of the diffraction experiment for internal stress measurement are recalled. Using the neutron and X-ray techniques, we have determined the first and the second order stresses for cold rolled steel.
The aim of this radiological micro-CT study and meta-analysis was to determine the morphological features of the root canal anatomy of the mandibular molars. The radiological study included micro-CT scans of 108 mandibular first, 120... more
The aim of this radiological micro-CT study and meta-analysis was to determine the morphological features of the root canal anatomy of the mandibular molars. The radiological study included micro-CT scans of 108 mandibular first, 120 mandibular second, and 146 mandibular third molars. For our meta-analysis, an extensive search was conducted through PubMed, Embase, and Web of Science to identify articles eligible for inclusion. Data extracted included investigative method (cadaveric, intraoperative, or imaging), Vertucci type of canal configuration, presence/number of canals, roots, apical foramina, apical deltas, and intercanal communications. In the mesial roots of mandibular molars, the most frequent Vertucci type of canal configuration was type IV, except for the mandibular third molar where type I was most common. Type I was most common in the distal root. There were usually two canals in the mesial root and one in the distal root. Two was the most common number of roots, and a ...
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The goal work of this work is to describe the qualitative and quantitative behaviour of titanium T40 during tensile test. Material characteristics were determined using EBSD and X-ray techniques. Textures, twin boundary fractions,... more
The goal work of this work is to describe the qualitative and quantitative behaviour of titanium T40 during tensile test. Material characteristics were determined using EBSD and X-ray techniques. Textures, twin boundary fractions, residual stresses and coherent domain size were determined. It was found that deformation mechanisms and microstructure characteristics are different in the samples stretched along rolling and transverse directions. For example the average grain size, as determined from EBSD measurements, is higher in the sample stretched along rolling direction. Also smaller coherent domains form and residual stress is more easily relaxed in this sample. A strong appearance of tensile twins was observed in the samples deformed along transverse direction. In the present paper a complex study of material characteristics and deformation mechanisms is presented. A special emphasis is done on residual stress characteristics determined in the samples stretched in two perpendicu...
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is study presents effects of volumetric reconstructions of the petrous bone anatomy obtained from image data delivered by the medical CT scanner (Optima CT 660) and micro-CT scanner (Nanotom 180N) used in biological and technical... more
is study presents effects of volumetric reconstructions of the petrous bone anatomy obtained from image data delivered by the medical CT scanner (Optima CT 660) and micro-CT scanner (Nanotom 180N) used in biological and technical applications. Although most of the osseous structures of the ear were visible in the subsequent serial CT scans delivered by the computed tomography system (Optima CT 660), their composition into volume was not satisfactory for viewing as a three-dimensional reconstruction. Micro-CT imaging of the anatomical structures of the petrous bone performed by the Nanotom 180N device was considerably superior to the medical computed tomography and the reconstructed anatomical structures presented a high level of accuracy and very realistic appearance.
The current study presents high resolution reconstructions showing the course of the facial canal within the temporal bone and visualizes the spatial orientation of the subsequent segments of the facial canal. 3D reconstructions of the... more
The current study presents high resolution reconstructions showing the course of the facial canal within the temporal bone and visualizes the spatial orientation of the subsequent segments of the facial canal. 3D reconstructions of the facial canal were created from micro-CT data obtained from the right and left human temporal bones of an adult individual of the male sex. For this purpose, volume and surface rendering was applied. 3D models of the facial canal and adjacent osseous structures comprehensively revealed its intricate course and depicted the spatial orientation of its subsequent segments: labyrinthine, tympanic and mastoid. The labyrinthine segment of the facial canal was clearly displayed in the horizontal plane whereas the tympanic and mastoid segments were entirely visible in the sagittal plane, which lines up along the long axis of the petrous part of the temporal bone.
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The generalized deterministic vertex model was successfully used to study the recrystallization process and the corresponding results were published elsewhere [1]. In its classical form the vertex model has analytical formulation, basing... more
The generalized deterministic vertex model was successfully used to study the recrystallization process and the corresponding results were published elsewhere [1]. In its classical form the vertex model has analytical formulation, basing on the total energy (i.e. boundary energy and stored energy) minimization. A change of grain boundary configuration in classical vertex model is found by the calculation of vertex velocities. Consequently, a global and complex system of equations has to be solved in each step. In order to simplify calculations and to handle the problem in a more flexible way, the statistical model was proposed. Typical elements of Monte Carlo algorithm were incorporated into the vertex model: a random (and small) modification of microstructure is accepted with the probability proportional to Boltzmann factor. This approach is closer to the stochastic nature of recrystallization process. The model was used to study the recrystallization of 70% and 90% cold rolled polycrystalline copper. It predicts correctly recrystallization textures for high and low strains.
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Research Interests: Algorithms and Texture
EBSD investigation of texture and microstructure evolution during a complete thermomechanical treatment of commercially pure titanium (HCP-Ti) is presented. Titanium was cold rolled to reach various degrees of thickness reduction: 20%,... more
EBSD investigation of texture and microstructure evolution during a complete thermomechanical treatment of commercially pure titanium (HCP-Ti) is presented. Titanium was cold rolled to reach various degrees of thickness reduction: 20%, 40% and 60%. Next, annealing in air atmosphere was conducted at different conditions to achieve the recrystallized state. EBSD topological maps were measured on RD-TD and RD-ND surface of each sample. Strong heterogeneity of deformed titanium microstructures is described with focus on the important role of twinning mechanisms. Texture evolution in investigated titanium appears to be limited, especially in recrystallized state. However some subtle mechanisms are discussed.
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Due to its pleiotropic effects, the commonly used drug metformin has gained renewed interest among medical researchers. While metformin is mainly used for the treatment of diabetes, recent studies suggest that it may have further... more
Due to its pleiotropic effects, the commonly used drug metformin has gained renewed interest among medical researchers. While metformin is mainly used for the treatment of diabetes, recent studies suggest that it may have further application in anticancer and antiaging therapies. In this study, we investigated the proliferative potential, accumulation of oxidative stress factors, and osteogenic and adipogenic differentiation potential of mouse adipose-derived stem cells (MuASCs) isolated from mice treated with metformin for 8 weeks. Moreover, we investigated the influence of metformin supplementation on mice bone density and bone element composition. The ASCs isolated from mice who were treated with metformin for 8 weeks showed highest proliferative potential, generated a robust net of cytoskeletal projections, had reduced expression of markers associated with cellular senescence, and decreased amount of reactive oxygen species in comparison to control group. Furthermore, we demonst...
Research Interests: Oxidative Stress, Adipose tissue, Cell Differentiation, Metformin, Reactive Oxygen Species, and 15 moreMice, Animals, Bone Density, Adipogenesis, Osteocalcin, Osteopontin, Superoxide Dismutase, Immunophenotyping, Osteogenesis, X Ray Microtomography, Cell Survival, Bone and Bones, Enzyme Linked Immunosorbent Assay, Mesenchymal Stromal Cells, and real time polymerase chain reaction
In the paper authors presented the application of specific method of assessment chosen properties of coating layer, that give additional information strictly connected with its tribology properties. Nanotomography techniques and 3D image... more
In the paper authors presented the application of specific method of assessment chosen properties of coating layer, that give additional information strictly connected with its tribology properties. Nanotomography techniques and 3D image processing gives quantitative and qualitative information about the testing sample, with no negative effects on the exanimating layer. Two samples, one with and one without the laser treatment were tested, measured and obtained results presented and discussed. Those preliminary research shown that proposed method can be recommended to application as a supplementary test of the properties coating layers and for verification of technological process parameters on the stage of working out the production process.
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ABSTRACT The main purpose of the present work is to describe the qualitative and quantitative behaviours of aluminium during high strain plastic deformation and the effect of deformation on the subsequent recrystallization process. An... more
ABSTRACT The main purpose of the present work is to describe the qualitative and quantitative behaviours of aluminium during high strain plastic deformation and the effect of deformation on the subsequent recrystallization process. An Electron Backscatter Diffraction analysis of aluminium after the Equal channel angular pressing (ECAP) and recrystallization process is presented. In order to do this, several topological maps are measured for samples processed by 4 and 8 passes and recrystallized. The processing was conducted with route C. For all samples, distributions of grain size, misorientation, image quality factor (IQ) and texture were preceded and then analysed in some detail. Crystallographic texture analysis Plastic anisotropy Heterogeneity Recrystallization 1. Introduction Intense plastic deformation (in literature, severe plastic deformation — SPD) is increasingly used for fragmentation of the microstructure, because it allows one to obtain ultra fine grain (UFG) materials. Ultra fine grain materials have an average grain size between ~250 nm and 1 μm, and typically a fine grain size is accompanied by a high fraction (60–70% for aluminium) of high angle boundaries [1]. This microstructure evolution cannot be achieved in more conventional processes because of the limit imposed on the total strain introduced during deformation. Equal channel angular pressing (ECAP) has been widely studied as the most promising SPD method [2]. The process consists of two die channels equal in cross section, intersecting at ϕ angle. Values of intersection angle ϕ ranging from 60° to 150° have been reported in literature, but ϕ=90° and 120° are the most frequently used. The additional angle ψ defines the arc of curvature at the outer point of intersection of the two channels. The process, although discontinuous, can be repeated many times with or without a rotation of 90° or 180° around the extrusion axis, accordingly designated as routes A, B (B A or B C) and C, respectively. Products made with this technique are characterised by high yield and ultimate tensile stress compared to their coarse grained counterparts [3]. They can potentially be used for super-plastic forming. More recently, a super-plastic forming capability was demonstrated directly for an Al alloy after processing by ECAP [4]. These and other results confirm the potential for developing super-plastic ductilities in the ultra fine grain materials processed by SPD [5]. Microstructure fragmentation and strain heterogeneities were studied by other authors using various techniques (X-ray, SEM, TEM, EBSD, AFM, etc.) [6–10], but all the studies have a qualitative character. The aim of this work is to describe, qualitatively and quantitatively, the microstructure fragmentation and its N 7 8 (2 0 1 3) 6 0 – 6 8
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Plastic deformation induces the dislocation and residual stress fields, which rest in a material after releasing of applied external forces. One can distinguish the stored energy connected with dislocation density and that with residual... more
Plastic deformation induces the dislocation and residual stress fields, which rest in a material after releasing of applied external forces. One can distinguish the stored energy connected with dislocation density and that with residual stresses. The stored energy distributions can be determined experimentally by diffraction experiments and also can be predicted by deformation models. The so obtained distributions of the stored energy versus crystal orientation were correlated with deformation and recrystallization textures of low carbon steel.
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The prediction of the mechanical properties of trabecular bone is usually based on in vitro measurements of real samples via Micro Computed Tomography (MicroCT) combined with Finite Element Method (FEM). The aim of this study was to... more
The prediction of the mechanical properties of trabecular bone is usually based on in vitro measurements of real samples via Micro Computed Tomography (MicroCT) combined with Finite Element Method (FEM). The aim of this study was to compare such an approach with the homogenization techniques: Mori-Tanaka, Self-Consistent and Incremental Scheme, well established for composite materials, to determine the full elastic constant tensor of the trabecular bone.
ABSTRACT A general X-ray multireflection method was applied to determine the stress level in deformed and recrystallised polycrystalline copper samples. Different reflections hkl were simultaneously used in the fitting procedure. The... more
ABSTRACT A general X-ray multireflection method was applied to determine the stress level in deformed and recrystallised polycrystalline copper samples. Different reflections hkl were simultaneously used in the fitting procedure. The anisotropic diffraction elastic constants were calculated using the self consistent model and crystallographic texture. A significant decrease of the first order residual stresses was observed during recovery and recrystallisation. Diffraction peak widths and intensities were also examined for a few characteristic texture components during the recrystallisation process. Independently, synchrotron radiation and electron backscatter diffraction techniques were used to determine the stored energy in the examined material. The main result is that residual stress components start to reduce already before the recrystallisation process. The stored energy is strongly orientation dependent. It has the lowest value in the cubic texture component, which is dominating one in recrystalisation texture.
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Texture formation through strain induced boundary migration (SIBM) was investigated. Temper rolling reduction before final annealing for SIBM was varied between 0 and 26% and grain sizes and textures were measured using EBSD. In the... more
Texture formation through strain induced boundary migration (SIBM) was investigated. Temper rolling reduction before final annealing for SIBM was varied between 0 and 26% and grain sizes and textures were measured using EBSD. In the specimen which was temper rolled to 5%, in which grain growth by SIBM occurred most efficiently, a strong Goss component (which was a minor component after rolling), developed during annealing. From the EBSD image quality analysis, it was found that stored energy increased significantly in the Goss component with strain (from 5 to 9 %), whereas it was always relatively small in the D-Cube component ({001}<110>), compared to Goss and g-fibre components. Based on these results, a mechanism of grain growth by SIBM was suggested. Texture evolution during annealing could thus be explained by the hypothesis, speculated from the analysis of orientation stability, that D-Cube grains are associated with more homogeneous dislocations distributions than Goss ...
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A newly developed model based on vertex concept is presented in this paper. Contrary to its standard version, which is strictly deterministic, some concepts of Monte-Carlo type method were introduced. It makes the model more flexible and... more
A newly developed model based on vertex concept is presented in this paper. Contrary to its standard version, which is strictly deterministic, some concepts of Monte-Carlo type method were introduced. It makes the model more flexible and allows to introduce some parameters appearing in vertex movement equations, which are not easy to express in analytical form. Initial microstructure in the model is characterized by topology, crystallographic orientations and stored energy values of the grains. The boundary energies and mobilities are anisotropic in general. Nucleation mechanism of a given type is selected at the beginning of calculations. Deformation texture, stored energy distribution and initial microstructure are input parameters of the model. The aim of the calculations is to predict the texture and microstructure modifications during recrystallization. The model was also applied to the study of the kinetics of grain growth and recrystallization. The preliminary tests of the mo...
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ABSTRACT Eight years ago recrystallization of OFE (oxygen-free electronic) copper was examined in detail using various techniques. In 2008 exactly the same material was measured using EBSD microscopy. The deformed state and fully... more
ABSTRACT Eight years ago recrystallization of OFE (oxygen-free electronic) copper was examined in detail using various techniques. In 2008 exactly the same material was measured using EBSD microscopy. The deformed state and fully recrystallized state have been analyzed and compared with data obtained eight years ago. The stored energy (SE) estimated by Image Quality (IQ) analysis was compared in these two cases. A significant amount of recovery took place in the sample, but only in some texture components. Some others present more or less the same SE as eight years ago. The textures of recrystallized samples were compared. We observed that the difference in SE distribution between the two deformed state has an influence on the final textures after recrystallization. Our study confirms the hypothesis that if a grain (orientation) has distinctly lower SE than other orientations - it has the highest growth preference (threshold hypothesis). Such grains (orientations) are dominant in the recrystallization texture.
Plastic deformation induces the dislocation and residual stress fields, which rest in a material after releasing of applied external forces. One can distinguish the stored energy connected with dislocation density and that with residual... more
Plastic deformation induces the dislocation and residual stress fields, which rest in a material after releasing of applied external forces. One can distinguish the stored energy connected with dislocation density and that with residual stresses. The stored energy distributions can be determined experimentally by diffraction experiments and also can be predicted by deformation models. The so obtained distributions of the stored energy versus crystal orientation were correlated with deformation and recrystallization textures of low carbon steel.
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Research Interests: Algorithms and Texture
ABSTRACT It is well known that the energy stored during plastic deformation is a driving force in the recrystallization process. The goal of the present work is to find the best parameter (among a few ones predicted by deformation models)... more
ABSTRACT It is well known that the energy stored during plastic deformation is a driving force in the recrystallization process. The goal of the present work is to find the best parameter (among a few ones predicted by deformation models) controlling the kinetics of recrystallization process, hence playing a role of the stored energy. The recrystallization was studied in the frame of a Monte Carlo model; the stored energy (and its orientation distribution) is an input data. Finally, it was found that the best parameters are: the average dislocation density and the total plastic work. Roughly, they have similar distributions in function of orientation and they predict practically the same recrystallization textures.
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Recently, some authors have used the Monte Carlo modelling using complete set of experimental data to get a better correlation between experimental observations and calculations concerning recrystallization process [1, 2]. Simulations... more
Recently, some authors have used the Monte Carlo modelling using complete set of experimental data to get a better correlation between experimental observations and calculations concerning recrystallization process [1, 2]. Simulations using Monte Carlo technique have been performed these last years for IF-Ti steels in order to predict the microstructure and the texture evolution after high reduction amounts by cold rolling [3, 4]. On the contrary, in the present work, this evolution is simulated in an IF-Ti steel cold rolled after low deformation amount (reduction amount R = 40 %). Microstructure is characterized by Electron Back-Scattered Diffraction and introduced in the model. The quality index of the Kikuchi patterns (EBSD data) is used to qualitatively evaluate the stored energy for each grain. Different hypothesis of nucleation mechanisms have been introduced into the model. It has been shown that the better recrystallization texture correlation between experiment and simulati...
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In order to simulate the recrystallization process, Monte Carlo modelling has been applied to the case of wire-drawn copper deformed to a moderate strain. The complete experimental set of data was taken mainly from Electron Back Scattered... more
In order to simulate the recrystallization process, Monte Carlo modelling has been applied to the case of wire-drawn copper deformed to a moderate strain. The complete experimental set of data was taken mainly from Electron Back Scattered Diffraction measurements in a Scanning Electron Microscope. Several nucleation hypothesis have been introduced and tested into the model. It has been shown that nucleation taking into account the sites associated with the highest stored energy and highest local misorientation leads to the best results in terms of recrystallization microstructure and texture. An important number of new orientations - that come only from annealing twinning - are not reproduced with the model, indicating the major role of this particular mechanism during the recrystallization process.
Research Interests: Monte Carlo and Copper
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The recrystallization process in polycrystalline material was studied using the newly developed two–dimensional model based on the vertex concept. In the model presented below the microstructure of polycrystalline material is represented... more
The recrystallization process in polycrystalline material was studied using the newly developed two–dimensional model based on the vertex concept. In the model presented below the microstructure of polycrystalline material is represented by two-dimensional network of grains. The initial microstructure is characterized by topology, crystal orientations and stored energy values of the grains. The boundary energies and mobilities are anisotropic in general. Additional driving forces in recrystallization, are exerted on vertices and are derived from the stored energy gradients between adjacent grains. The nucleation mechanism of a given type is selected at the start of the calculations. Two different nucleation types were tested. Deformation texture, stored energy distribution and initial microstructure are input parameters of the model. The goal of the calculations is the prediction of texture and microstructure modification during recrystallization. A comparison of predicted and exper...
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