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    Wyświetlanie 1-8 z 8
    Tytuł:
    Changes in the mechanical properties of femoral cartilage tissue in advanced osteoarthritis
    Autorzy:
    Dragan, Szymon Ł.
    Kuropka, Piotr
    Kulej, Mirosław
    Gabryś, Piotr
    Nikodem, Anna
    Powiązania:
    https://bibliotekanauki.pl/articles/306228.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    tkanka chrzęstna
    histologia
    właściwości mechaniczne
    cartilage tissue
    osteoarthritis
    indentation test
    histology
    mechanical properties
    Opis:
    The main goal of this article was the analysis of the changes of mechanical properties, thickness and histology of the cartilage in different regions of the femur head in advanced stage of the osteoarthritis. Methods: The study material consisted of cylindrical specimens (9.7 mm) prepared form proximal epiphysis of the human femur bone after hip arthroplasty. The thickness was determined from the reconstruction of the specimen from microtomography (SkyScan 1172, Bruker®) images. Mechanical properties of the cartilage tissue were identified in static indentation test conducted the use of MTS® Synergie 100 testing machine. Histological study enabled us to determine cartilage total thickness as well as location and orientation of the collagen fibers. Results: Depending on the region of the head, the cartilage tissue thickness was in the range (0.74–2.23 mm). The lowest thickness values were obtained for the R5 region and the lowest for R4. Samples from R1–R4 regions differ by 24%. Measurements of cartilage tissue indentation, determined with the help of Hayes’ formula, showed that the values of mechanical parameters in regions R1, R2, R3 and R5 have similar values (the difference between them is about 5.5%). Region R4, which had the smallest thickness, also had the lowest values of mechanical parameters. Conclusions: Using κ coefficients, proposed by Hayes, enabled us to obtain similar values of mechanical parameters in the regions R1, R2, R3 and R5, despite differences in cartilage tissue thickness. The R4 region, which had the weakest mechanical parameters, was characterized by the strongest reduction of the articular cartilage tissue, which was accompanied by an unformed mass of cartilage residue originating from the abraded surface and bursa fluid.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2020, 22, 1; 143-152
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Skinfold creep under load of caliper. Linear visco- and poroelastic model simulations
    Autorzy:
    Nowak, J.
    Nowak, B.
    Kaczmarek, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/306928.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    symulacja komputerowa
    tkanka miękka
    lepkosprężystość
    modelowanie
    computer simulations
    soft tissue
    lymphoedema
    viscoelasticity
    poroelasticity
    modeling
    Opis:
    Purpose: This paper addresses the diagnostic idea proposed in [11] to measure the parameter called rate of creep of axillary fold of tissue using modified Harpenden skinfold caliper in order to distinguish normal and edematous tissue. Our simulations are intended to help understanding the creep phenomenon and creep rate parameter as a sensitive indicator of edema existence. The parametric analysis shows the tissue behavior under the external load as well as its sensitivity to changes of crucial hydro-mechanical tissue parameters, e.g., permeability or stiffness. Methods: The linear viscoelastic and poroelastic models of normal (single phase) and oedematous tissue (twophase: swelled tissue with excess of interstitial fluid) implemented in COMSOL Multiphysics environment are used. Simulations are performed within the range of small strains for a simplified fold geometry, material characterization and boundary conditions. The predicted creep is the result of viscosity (viscoelastic model) or pore fluid displacement (poroelastic model) in tissue. Results: The tissue deformations, interstitial fluid pressure as well as interstitial fluid velocity are discussed in parametric analysis with respect to elasticity modulus, relaxation time or permeability of tissue. The creep rate determined within the models of tissue is compared and referred to the diagnostic idea in [11]. Conclusions: The results obtained from the two linear models of subcutaneous tissue indicate that the form of creep curve and the creep rate are sensitive to material parameters which characterize the tissue. However, the adopted modelling assumptions point to a limited applicability of the creep rate as the discriminant of oedema.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2015, 17, 4; 39-48
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new medical device to measure a stiffness of soft materials
    Autorzy:
    Oflaz, H.
    Baran, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/307281.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    soft tissue
    dermatologic disorder
    stiffness
    biomechanics
    durometer
    biomedical engineering
    tkanka miękka
    sztywność
    biomechanika
    inżynieria biomedyczna
    Opis:
    An objective in vivo measurement technique for assessing the material properties of soft tissue would be a valuabe tool in diagnosing dermatological pathologies. In order to make advancements in this field, a new hand-held device was designed to measure the stiffness of soft materials. The device measures the reaction forces experienced by the soft tissue under constant indentation deformations at the time of stiffness measurement. Agarose gel samples were prepared in a range of molarities to mimic the stiffness variabilities found in vivo. The stiffness of each gel was evaluated using two different measurement techniques. The first method utilized an industry standard durometer, designed to measure the hardness of materials in shore type 00 scales of soft plastics. The second measurement was taken using an original custom-built soft tissue stiffness meter, designed specifically for the present study. These two devices were compared and a strong correlation was found between them (r2 = 1.00, Spearman rank test). Additionally, it was observed that gels of different stiffness could be distinguished by both devices. In conclusion, the soft tissue stiffness can be accurately evaluated using the proposed device. The new device should be evaluated on human subjects in future studies, before it can be used to assess soft tissue disorders.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2014, 16, 1; 125-131
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessment of corneal and fatty tissues biomechanical response in dynamic tonometry tests by using inverse models
    Autorzy:
    Jannesari, M.
    Kadkhodaei, M.
    Mosaddegh, P.
    Kasprzak, H.
    Behrouz, M. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/307551.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    biomechanika rogówki
    okulistyka
    tkanka tłuszczowa
    tonometria
    corneal biomechanics
    fatty tissue
    dynamic tonometry
    inverse finite element method
    Opis:
    The assessment of corneal biomechanics is essential for studying ophthalmological operations, such as refractive surgeries, and for more accurate estimation of intraocular pressure. The chief aim of the current study is to characterize corneal and fatty tissues in order to construct a model to predict eye globe behavior during dynamic tonometry tests. Methods: In the present study, images from corneal deformation, acquired from Corvis ST tonometer, were processed. Then, corneal pure displacement and eye globe retraction were calculated. Utilizing inverse finite element method, corneal material properties were calculated in order to predict pure deformation obtained from Corvis ST. Using a similar approach, material parameters of fatty tissue were estimated in order to predict the eye globe retraction. The model used for fatty tissue was considered as corneal boundary condition in a forward finite element model to create a joint model, which could simulate corneal behavior in dynamic tonometry tests. Results: It was shown that an isotropic material model is accurate enough to predict corneal deformation in dynamic tonometry tests. Moreover, effects of IOP on the estimated material properties were investigated. Finally, utilizing the joint model, it was demonstrated that there is strong correlation between corneal stiffness and the biomechanical parameter introduced by Corvis ST. Conclusions: An eye globe model was constructed and characterized by two distinct inverse models for corneal and fatty tissue. This model can be utilized for predicting eye globe behavior during dynamic tonometry tests besides other ophthalmological operations.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2018, 20, 1; 39-48
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental testing and constitutive modeling of the mechanical properties of the swine skin tissue
    Autorzy:
    Łagan, S. D.
    Liber-Kneć, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/306666.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    materiał hipersprężysty
    tkanka miękka
    próba rozciągania
    model konstytutywny
    hyperelastic material
    soft tissue
    tensile test
    pig’s skin
    constitutive model
    Opis:
    The aim of the study was an estimation of the possibility of using hyperelastic material models to fit experimental data obtained in the tensile test for the swine skin tissue. Methods: The uniaxial tensile tests of samples taken from the abdomen and back of a pig was carried out. The mechanical properties of the skin such as the mean Young’s modulus, the mean maximum stress and the mean maximum elongation were calculated. The experimental data have been used to identify the parameters in specific strain-energy functions given in seven constitutive models of hyperelastic materials: neo-Hookean, Mooney–Rivlin, Ogden, Yeoh, Martins, Humphrey and Veronda–Westmann. An analysis of errors in fitting of theoretical and experimental data was done. Results: Comparison of load –displacement curves for the back and abdomen regions of skin taken showed a different scope of both the mean maximum loading forces and the mean maximum elongation. Samples which have been prepared from the abdominal area had lower values of the mean maximum load compared to samples from the spine area. The reverse trend was observed during the analysis of the values of elongation. An analysis of the accuracy of model fitting to the experimental data showed that, the least accurate were the model of neo- -Hookean, model of Mooney–Rivlin for the abdominal region and model of Veronda–Westmann for the spine region. Conclusions: An analysis of seven hyperelastic material models showed good correlations between the experimental and the theoretical data for five models.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2017, 19, 2; 93-102
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-integer viscoelastic constitutive law to model soft biological tissues to in-vivo indentation
    Autorzy:
    Demirci, N.
    Tönük, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/307448.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    rachunek niecałkowitego rzędu
    tkanka miękka
    lepkosprężystość
    fractional calculus
    indentation tests
    inverse finite element analysis
    soft tissue constitutive relation
    viscoelasticity
    Opis:
    Purpose: During the last decades, derivatives and integrals of non-integer orders are being more commonly used for the description of constitutive behavior of various viscoelastic materials including soft biological tissues. Compared to integer order constitutive relations, non-integer order viscoelastic material models of soft biological tissues are capable of capturing a wider range of viscoelastic behavior obtained from experiments. Although integer order models may yield comparably accurate results, non-integer order material models have less number of parameters to be identified in addition to description of an intermediate material that can monotonically and continuously be adjusted in between an ideal elastic solid and an ideal viscous fluid.Methods: In this work, starting with some preliminaries on non-integer (fractional) calculus, the “spring-pot”, (intermediate mechanical element between a solid and a fluid), non-integer order three element (Zener) solid model, finally a user-defined large strain non-integer order viscoelastic constitutive model was constructed to be used in finite element simulations. Using the constitutive equation developed, by utilizing inverse finite element method and in vivo indentation experiments, soft tissue material identification was performed. Results: The results indicate that material coefficients obtained from relaxation experiments, when optimized with creep experimental data could simulate relaxation, creep and cyclic loading and unloading experiments accurately.Conclusions: Non-integer calculus viscoelastic constitutive models, having physical interpretation and modeling experimental data accurately is a good alternative to classical phenomenological viscoelastic constitutive equations.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2014, 16, 4; 13-21
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of the impact of decellularization and sterilization on tensile strength transgenic porcinedermal dressings
    Autorzy:
    Joszko, Kamil
    Gzik-Zroska, Βożena
    Kowalewska, Edyta
    Klama-Baryła, Agnieszka
    Suchoń, Sławomir
    Burkacki, Michał
    Wolański, Wojciech
    Powiązania:
    https://bibliotekanauki.pl/articles/307164.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    tkanka skórna
    oparzenie
    analiza statystyczna
    rekonstrukcja
    skin tissue
    burn wounds treatment
    xenogeneic grafts
    static tensile test
    statistical analysis
    reconstructive surgery
    Opis:
    The aim of this paper was to evaluate which method of acellularization and sterilization is optimal, in the meaning of which processes have the least impact on the deterioration of mechanical properties of porcine tissues used for xenogeneic applications. Methods: The static tensile probe was conducted for 80 skin specimens obtained from transgenic swine, which are used as a wound dressing for skin recipient. Obtained data were subsequently analyzed with the use of statistical methods. Results: It was found that Young’s modulus for the samples after the sterilization process for the dispase substance and the mixed method (SDS + trypsin) were statistically significantly changed. In the case of dispase, Young’s modulus value before the sterilization process was 12.4 MPa and after the value increased to 28.0 MPa. For the mixed method (SDS + trypsin) before the sterilization process Young’s modulus value was 5.6 MPa and after it was increased to 6.3 MPa. The mixed method (SDS + trypsin) had the slightest effect on changing the mechanical properties of the samples before and after the sterilization process. Conclusions: It was confirmed that different methods of acellularization and the process of sterilization have an influence on the change of mechanical properties of the skin of transgenic swine. In the authors’ opinion, the mixed method (SDS + trypsin) should be recommended as the best one for the preparation of transgenic porcine dermal dressings because it ensures a smaller probability of dressing’s damage during a surgical procedure.
    Źródło:
    Acta of Bioengineering and Biomechanics; 2019, 21, 3; 87-97
    1509-409X
    2450-6303
    Pojawia się w:
    Acta of Bioengineering and Biomechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distinctness of shaping form and the context of place – open landscape and urban structure
    Odmienność kształtowania formy a kontekst miejsca – krajobraz otwarty i tkanka miejska
    Autorzy:
    Konior, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/1835609.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    contemporary architecture
    architectural design
    site context
    open landscape
    urban structure
    architektura współczesna
    projektowanie architektoniczne
    kontekst miejsca
    krajobraz otwarty
    tkanka miejska
    Opis:
    The subject of this publication represents thoughts and reflections of an architect-practitioner, concerning the differences in shaping architecture depending on the context of the location. The subject of our considerations are buildings designed under the supervision of the author of this text, in Konior Studio. Two examples of buildings in an open landscape are presented: Gymnasium and Cultural Center in Warsaw Białołęka, located outside the urban area, on the edge of the Vistula River, and an office building that is the head office of Press Glass in Konopiska, located in a transformed, green area of a former agricultural wasteland. The next two examples concern buildings located in the urban structure: the Symphony building, which is an extension of the Academy of Music in Katowice, and the building of the State Music School Complex in Warsaw. The author analyzes distinctiveness in the designer’s way of thinking as well as distinctiveness in the solutions shaping architecture depending on the context of place. He also underlines the importance of continuity of thought from the sketch-dream which contains the main idea of the structure, until its implementation. The text is based on relevant literature, supported by in situ research done on characteristic buildings, as well as the architect’s own experiences from the designing process and building development, which served as an illustration of the theses put forth.
    Tematem artykułu są przemyślenia i refleksje architekta-praktyka dotyczące relacji, jakie zachodzą pomiędzy kształtowaniem architektonicznej formy a kontekstem przestrzennym otaczającego środowiska. Przedmiotem rozważań są budynki zaprojektowane pod kierunkiem autora niniejszego tekstu w autorskiej pracowni Konior Studio. Obiekty w krajobrazie otwartym zaprezentowano na przykładzie Gimnazjum i Centrum Kultury zlokalizowanym poza terenem zurbanizowanym, na brzegu Wisły w Warszawie-Białołęce oraz biurowca będącego siedzibą główną firmy Press Glass, usytuowanego na przekształconym, zielonym obszarze dawnych nieużytków rolnych. Kolejne dwa przykłady – ulokowane w tkance miejskiej – to budynek „Symfonii”, będący rozbudową Akademii Muzycznej w Katowicach oraz siedziba Zespołu Państwowych Szkół Muzycznych w Warszawie. Autor analizuje odmienność sposobu myślenia projektanta oraz odmienność rozwiązań kształtujących architekturę w zależności od kontekstu miejsca. Wskazuje także na wagę ciągłości myśli: od szkicu-marzenia, który zawiera główną ideę planowanego obiektu, aż po realizację. Podstawą jest literatura przedmiotu poparta badaniami in situ charakterystycznych obiektów oraz doświadczenia własne architekta wyniesione z procesu projektowania i realizacji budynków, które posłużyły za ilustrację prowadzonych rozważań.
    Źródło:
    Architectus; 2021, Nr 2 (66); 113-122
    1429-7507
    2084-5227
    Pojawia się w:
    Architectus
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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