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PL
Prezentowana praca dotyczy problematyki optymalizacji cech geometrycznych oraz własności mechanicznych stentów wieńcowych wykonanych ze stali Cr-Ni-Mo. W pracy przedstawiono metodologię wyznaczania charakterystyki biomechanicznej układu stent-naczynie wieńcowe. Na jej podstawie dobrano własności mechaniczne stali, z której wykonano stenty. Weryfikację cech geometrycznych oraz własności mechanicznych stentów wieńcowych przeprowadzono na podstawie testów in vitro poprzez implantowanie ich do fantomu naczynia. Przeprowadzone testy potwierdziły prawidłowość doboru własności mechanicznych stali Cr-Ni-Mo, z której zostały wykonane stenty.
EN
Presented work concerns the issue of optimization of geometry and mechanical properties of coronary stents made of Cr-Ni-Mo steel. The methodology of determining the biomechanical characteristic of a stent - coronary vessel system was presented. The biomechanical characteristic, was the basis for the selection of mechanical properties of the stents were made of steel. The verification of geometrical features and mechanical properties of the coronary stents was carried out on the basis of in vitro tests by implantation of the stent into an artificial vessel. Tests confirmed the correct selection of the mechanical properties of the applied steel.
2
Content available remote Use of coronary stents - material and biophysical conditions
100%
EN
Purpose: The paper discusses application issues of using the metallic implants for treatment of the cardiovascular diseases. The analysis of the biophysical conditions of the heart – coronary vessels system has been used to distinguish the tissue environment properties which should be compatible with properties of the metal biomaterial and stent’s surface. On this basis the author presented results of experiments concerning the usefulness of the passive-carbon layer for surface treatment of vascular stents made of stainless steel. Design/methodology/approach: In order to determine the usefulness of the layer for implants in cardiology the following tests were carried out on the layer: structure, thickness, corrosion resistance, electrical properties and biocompatibility in experimental animals. The structure and thickness of the layer were tested in high resolution transmission electron microscope. Corrosion resistance was carried out by recording anodic polarization curves. Methodology of measurements took into consideration both implantation conditions and application of vascular stents. In tests concerning electrical properties of the layer, current-potential as well as capacity-potential characteristics were determined. Findings: The passive-carbon layer of nanocrystlline structure and high smoothness created on coronary stents’ surface fully ensures pitting corrosion resistance in both implantation and application conditions. Research limitations/implications: Deposition of the dielectric carbon layer on coronary stents’ made of stainless steel is effective method of reducing reactivity of their surface in blood environment and blood clotting in consequence. Originality/value: The need to determine the correct quality and properties of coronary stents was indicated. The properties refer to stents’ design, physio-chemical properties of the metallic biomaterial and its surface. Keywords: Biomaterials; Cr-Ni-Mo steel; Corrosion resistance; Electrical properties; Coronary stents
PL
W artykule przedstawiono wyniki badań odporności korozyjnej odlewniczego stopu Co-Cr-Mo z naniesioną warstwą węglową przy różnicowanej jego strukturze i sposobie przygotowania powierzchni. Zbadano strukturę stopu w stanie lanym i przesyconym oraz odporność na korozję wżerową metodą potencjodynamiczną w warunkach symulujących środowisko tkankowe. Ogólnie stwierdzono, że o własnościach fizykochemicznych warstwy węglowej decyduje ilość węglików występujących w osnowie metalicznej, jak też obecność warstwy pasywnej wytworzonej na podłożu metalicznym.
EN
The paper presents the results of investigations on the corrosion resistance of a carbon coated Co- Cr-Mo cast alloy with different structures and surface finish. The alloy was investigated in the as-cast condition and after a solution heat treatment. Resistance to pitting corrosion was tested using a potentiodynamic method in a simulated tissue environment it has been found that the number of carbides occurring in the metallic matrix and the presence of passive films on alloy surface have a decisive effect on physical and chemical properties of the carbon coating.
PL
Zasadniczym celem prezentowanej pracy była analiza biomechaniczna układu wiertło chirurgiczne - kość udowa w warunkach symulujących proces wiercenia w kości. Opracowano model geometryczny wiertła chirurgicznego o zróżnicowanej geometrii ostrza (2κ1 = 90° i 2κ2 = 120°) oraz krążka symulującego kość udową. Obliczenia przeprowadzono dla wiertła wykonanego ze stali X39Cr13. Efektem zrealizowanej analizy było wyznaczenie stanu odkształceń i naprężeń zredukowanych w części roboczej wiertła w funkcji obciążenia siłą F = 20-100 N i prędkością obrotową n = 2000 obr/min.
EN
The aim of the work was determination of biomechanical analysis of a surgical drill - bone system in simulated conditions of drilling in a bone. Geometrical models of the surgical drill of diverse geometry of the edge (2κ1 = 90° and 2κ2 = 120°) and the disc simulating femur were worked out. Calculations were carried out for the drill made of martensitic Steel (X39Cr13). The effect of numerical analysis was determination of strains and stresses in working part of the drill as a functional of the applied loading F = 20-100 N and rotational speed n = 2000 rpm.
6
Content available remote FEM analysis of drills used in bone surgery
63%
EN
Purpose: The aim of the work was determination of biomechanical analysis of a surgical drill – bone system in simulated conditions of drilling in a bone. Design/methodology/approach: Geometrical model of the selected surgical drill and simulated femur (cortical bone) was worked out in the Inventor Professional 2008. The value geometry of the edge was point angle (2κ1 = 90° and 2κ2 = 120°). Numerical model was prepared in ANSYS Workbench v. 11. Meshing was realized with the use of SOLID 187 elements. Evaluate boundary conditions to numerical analysis imitate phenomena in real system with appropriate accuracy. Drill was loaded with forces in the range F= 100-200 N and torque T = 0.04 Nm. Calculations were carried out for two kinds of metallic material of the drill. Findings: The effect of numerical analysis was determination of strains and stresses in working part of the drill. Results of analysis indicate diverse values of strains and stresses distribution in working part of the drill depending on its geometry. The maximum values of strains and stresses were obtained for the drill of point angle 2κ1=120°. Research limitations/implications: In order to simulate phenomena in real system, a simplified model of surgical drill – femur system was worked out. The simplifications concerned mostly geometry of a femur. The femur was represented by disc of height h = 10 mm, corresponding with thickness of cortical bone. Originality/value: The numerical analysis of the surgical drill – femur system in simulated conditions of drilling in a bone can be a basis for optimization of cutting edge geometry of surgical tools as well as for selection of their mechanical properties.
PL
W pracy przeprowadzono analizę numeryczną układu wiertło chirurgiczne - kość udowa z wykorzystaniem MES w warunkach symulujących proces wiercenia w kości. Dla wytypowanej postaci konstrukcyjnej wiertła opracowano modele geometryczne narzędzi uwzględniające zróżnicowaną geometrię ich ostrza, jak i średnicę. Przyjęte dla potrzeb analizy warunki brzegowe odwzorowywały zjawiska zachodzące w układzie rzeczywistym. Uzyskane wyniki stanowią podstawę doboru własności mechanicznych tworzywa metalowego wierteł, jak odpowiedniej geometrii ich ostrza.
EN
This work concentrates on the numerical analysis of a surgical drill- femur system under conditions simulating the bone drilling process, using a finite element method. Geometrical models of the surgical tools of diverse geometry of the edge and diameters were worked out for selected drills. The applied boundary conditions reflected phenomena in real system with appropriate accuracy. The obtained results are a basis for improvement of the drills’ geometry and optimization of their mechanical properties.
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2000
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tom R. 3, nr 9
22--26
PL
Badania przeprowadzono na ośmiu królikach, którym wszczepiono do światła kanału szpikowego grot z kompozytu węgiel-żywica epoksydowa pokryty hydroksyapatytem /C-ep-Hap/. Przeprowadzono badania strefy rozdziału pomiędzy implantem C-ep-Hap, a tkanką kostną oraz powierzchni bocznej implantu. Obserwacje przeprowadzono w elektronowym mikroskopie skaningowym DSM-940 firmy OPTON. Dla potrzeb badań przygotowano prze- kroje poprzeczne implantu łącznie z tkanką kostną. W przedstawianym materiale obserwowano bardzo wolno postępującą degradację kompozytu od obwodu implantu. Dopiero w końcowej fazie doświadczenia widać masywne przyleganie nowej tkanki kostnej do wolnych fragmentów kompozytu. Natomiast na przekroju poprzecznym implant sprawiał wrażenie nienaruszonego. Tak powolny proces biodegradacji kompozytu zapewnia samej uszkodzonej kości silniejszą i dłuższą stabilizację. Na podstawie przeprowadzonych obserwacji uzyskano zachęcające wyniki stwarzające większe kliniczne możliwości stosowania kompozytu C-ep-Hap niż kompozytu węgiel-węgiel.
EN
Investigations were carried out using eight rabbits, which were inserted, into the marrow cavity, a pin made of hydroxyapatite-coated carbon-epoxy resin composite (Gep-Hap). Examined was the C-ep-Hap implant and bone tissue interphase, as well as the lateral implant surface. Observations of the transverse sections of the implant along with the bone tissue under the OPTON DSM-940 scanning electron microscope indicated very slow degradation of the composite from the implant circumference. In the final stage of the experiment, only massive adhesion of the new bone tissue to the free composite fragments was visible. However, the implant seemed intact on its transverse section. The slow biodegradation of the composite ensures the damaged bone a stronger and longer stabilisation. The obtained results are encouraging and indicate better possibilities for clinical use of the C-ep-Hap composites in comparison with the carbon-carbon ones.
11
51%
EN
Purpose: The study analyses influence of surface modification of Si:Ti on physical and chemical properties of samples made from AISI 316L steel in solution simulating blood-vascular system. Design/methodology/approach: Sol-gel layer was selected on the ground of data from literature. TEOS and TET made the ground for initial solution. Application of the layer on the surface of samples made of AISI 316L steel was preceded by mechanical working - grinding (Ra = 0.40 μm) and mechanical polishing (Ra = 0.12 μm). Corrosion resistance tests were performed on the ground of registered anodic polarisation curves and Stern method. In order to evaluate phenomena that take place on the surface of the tested alloys EIS was also applied. The tests were performed in artificial blood plasma at the temperature of T = 37.0±1°C and pH = 7.0±0.2. Findings: Obtained results on the ground of voltammetric and impedance tests showed differentiated electrochemical properties of AISI 316L steel depending on the type of surface treatment. Practical implications: Suggested subject matter of the article supports development of entrepreneurship sector due to high social demand for this type of technologies and relatively easy way of putting obtained laboratory tests data into inductrial and clinical practice. Originality/value: Suggestion of proper variants of surface treatment with application of sol-gel method is meaningful in future perspective and it shall promote determination of technological conditions with precise parameters of creation of oxide layers on metallic implants made of AISI 316L steel that come into contact with blood.
EN
The influence of the wear rate of drills used in bone surgery on the temperature distribution in the femur models (Sawbones) is presented in the paper. Surgical drills of diameter d = 4.5 mm and diverse edge geometry (90° and 120°) were selected for the study. In order to carry out thermal analysis with the use of finite element, experimental studies of wear process were necessary. These studies, among others, consisted in determination of average values of axial forces and cutting torques as a function of the number of drilled holes. The study showed an impact of the drill geometry on values that describe cutting process. It was found that the greatest values of torques and axial cutting forces occur in drills of point angle of 120°. Next, in order to determine the effect of wear rate on the generation of temperature in the cutting zone, thermal analysis of the drilling process using the finite element method was carried out. It was found that higher temperatures in the bone are observed for drilling with the use of the drill of point angle equal to 120°, as in the experimental study. For the tools of such edge geometry the wear of cutting edge is more intensive and the generated temperature in femur for the wear land VBB = 0.32 mm has reached the critical value associated with the process of thermal necrosis.
13
Content available remote Numerical and experimental analyses of drills used in osteosynthesis
51%
EN
This paper presents the results of numerical analysis and experimental studies of the process of bone drilling using drills applied in osteosynthesis procedures. In the studies, two surgical drills with a diameter d = 4.5 mm and varying in drill point geometry 2k were used. Thermal analysis based on FEM allowed determining the distribution of temperatures generated in the bone as a function of rotational speed of the drill. The results indicate that both drill point geometry and rotational speed of the drill have influence on temperatures generated in bone tissue. Additionally, the range was determined for possible values of rotational speed, which does not initiate the process of thermal necrosis of bone. The experimental studies of the process of drilling in a femur model showed the impact of drill point geometry on the values describing the cutting process. It was concluded that the highest values of torques and axial forces during cutting occur in the tools with angle 2k2 = 120 (degrees).
14
Content available remote Physical properties and haemocompatibility of passive-carbon layer
51%
EN
Purpose: In the paper physical (surface topography, electrical properties) and antithrombogenic properties of the passive-carbon layer used for enhancing the surface properties of vascular stents made of Cr-Ni-Mo steel have been investigated. Design/methodology/approach: To characterize the electrical properties of carbon layer the silicon plate was used. The resistivity ρ and relative permittivity of the layer ε r have been determined on the basis of currentvoltage and capacitance-voltage characteristics. In vitro tests of biotolerance evaluation of the passive-carbon layer in blood environment have been carried out in the haemolysis tests (in the direct contact and from the extract) and in the blood clotting tests. Findings: The results of investigations have shown that deposition process of the passive-carbon layer of dielectric properties on the surface of implants made of Cr-Ni-Mo steel and used in interventional cardiology is an effective way of limiting the reactivity of their surface in blood environment and the blood clotting process in consequence. Research limitations/implications: Usefulness of the passive-carbon layer for interventional cardiology applications should be verified in in vivo tests. Originality/value: Modification of physical properties of surface of the metallic biomaterials applied in cardiovascular system by deposition of the passive-carbon layer which has dielectric properties limits the blood clotting process.
15
Content available Warstwy diamentowe na implantach dla traumatologii
51%
PL
Opracowano technikę wytwarzania powłok pasywno-diamentowych na implantach ze stali Cr-Ni-Mo stosowanych w traumatologii. Przeprowadzono badania struktury warstwy oraz jej własności fizykochemicznych w stymulowanych warunkach laboratoryjnych, głównie ze względu na odporność korozyjną. Oceniono także biotolerancję uszlachetnionych implantów w tkankach zwierząt doświadczalnych oraz w badaniach klinicznych. Nowa jakość implantów gwarantuje w pełni dobre cechy użytkowe. Uzyskane wyniki są obiecujące dla perspektywicznych zastosowań klinicznych.
EN
A method of deposition of passive-diamond coatings onto implants made of Cr-Ni-Mo steels applied in traumatology has been developed. Structure of the layer as well as its physicochemical properties under stimulated experimental conditions, mainly with respect to its corrosion resistance, have been investigated. Moreover, biotolerance of improved implants in tissues of experimental animals and during clinical examinations has been evaluated. The new quality of implants quarantees good useful properties. The obtained results are promising for future clinical applications.
17
Content available remote Electrochemical behavior of Co-Cr-W-Ni alloy with passive layer
51%
EN
In the paper the results of corrosion resistance and chemical composition investigations of passive layer formed on the im-plants surface made of Co-Cr-W-Ni alloy used in interventional cardiology have been presented. Corrosion resistance has been tested in the solution simulating environment of human blood at temperature 37+-1°C. Particularly, the investigations of crevice and pitting corrosion resistance have been realized with taking into account the implantation technique of vascular stents. Chemical composition investigations of the passive layer have been carried out with the use of X-ray Photoelectron Spectroscopy (XPS). The results of preliminary tests pointed out on the usefulness of surface treatment of stents made of Co-Cr-W-Ni alloy.
EN
Purpose: The subject of the research work is an analysis of surface roughness impact and the influence of the steam sterilisation process on physicochemical properties of samples made of Ti-6Al-4V and Ti-6Al-7Nb alloys after their exposure in a solution simulating the osseous environment. Design/methodology/approach: A surface roughness diversification of the samples made of Ti alloys was obtained with the aid of mechanical working – grinding and with the use of mechanical polishing. A corrosion resistance test was performed based on an anodic polarization curves recording. An Electrochemical Impedance Spectroscopy (EIS) method was used as well for assessment of the effects which occur on the surface of the examined alloys. Findings: The potentiodynamic studies showed favourable influence of steam sterilisation process (in an autoclave) on corrosion resistance of Ti alloys, regardless of the applied mechanical treatment. Exposition of the samples in Ringer’ solution caused further increase of corrosion resistance only for Ti-6Al-7Nb alloy. Analysis of impedance spectra showed presence of the capacitive passive layer for all tested variants. Research limitations/implications: Obtained results of potentiodynamic studies showed how a physicochemical condition of the samples surface, exposed to the solution simulating osseous system environment, was changing. In order to determine properties fully and surface structures of the Ti-6Al-4V and Ti-6Al-7Nb alloys after the sterilisation and the 60-day exposure to Ringer’ solution, impedance characteristics, obtained by means of EIS were determined. Differences of parameters describing electrical properties of the layers formed after the exposure to Ringer’ solution, are probably caused by a change of their chemical composition. Originality/value: The potentiodynamic and EIS studies of corrosion resistance in Ringer’ physiological solution allow to predict behaviour of Ti-6Al-4V and Ti-6Al-7Nb implants in osseous system environment.
EN
In recent years in the area of prosthetic treatment, great emphasise was put on leaving a residual dentition inside mouth. In a teeth after endodontic treatment or with broken crown a healthy root is a natural implant that can be used for further reconstruction. Use of posts-and-cores is one of possible methods of widely damaged tooth crowns treatment. There is a lot of different types of prefabricated posts-and-cores. Numerical analysis of the prefabricated post-and-core – tooth system was conducted by the authors. The prefabricated Flexi-Flange post-and-core from the Essential Dental System was selected for the analysis. The scope of the analysis has covered calculation of displacements, strains and stresses in each elements of the analysed system – depending on the applied post material and load applied on the prosthetic crown. The analysis reviled that there is a significant influence of the type of the post material and load on results. It was found that the most unfavourable variant of load is the one with force applied on the labial surface at the angle of 45° to the axis of the tooth. The results of the analysed system provided a valuable guidelines for proper design of its form, geometrical properties, selection of the mechanical properties and the optimal strengthening degree of metallic biomaterial.
20
Content available remote Corrosion resistance of Cr-Ni-Mo steel after sterilization process
51%
EN
Purpose: The aim of the work was to evaluate how the process of high pressure steam sterilization influences the pitting corrosion resistance of Cr-Ni-Mo steel used for implants production. Design/methodology/approach: Surfaces of samples were prepared by electrolytic polishing and chemical passivation. Samples were sterilized in steam with the use of different parameters of temperature, pressure and time. Corrosion resistance investigations were carried out with the use of potentiodynamic method. The test were realized in solution simulating human blood environment (artificial plasma) at the temperature of 37 ± 1 °C and pH=7.2. Parameters describing the corrosion resistance have been determined on the basis of analysis of anodic polarization curves. Findings: High pressure steam sterilization process improves all parameters relating to pitting corrosion resistance of Cr-Ni-Mo implantation steel that is: corrosion potential Ecorr, breakdown potential Eb, polarization resistance Rp, corrosion current density icorr and corrosion rate. The increase of sterilization time for constant parameters of temperature and pressure of steam was the important factor which improved significantly the corrosion resistance of tested samples. Research limitations/implications: Further investigations of chemical composition of the layers formed during sterilization process are planed. Originality/value: The obtained results show the advantageous influence of passivation and high pressure steam sterilization on the pitting corrosion resistance of Cr-Ni-Mo steel in solution simulating human blood environment (artificial plasma).
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