Wojciech Piekarczyk

Application of β-1,3-glucan in production of ceramics-based elastic composite for bone repair

BackgroundUnsatisfactory surgical handiness is a commonly known disadvantage of implantable granular bioceramics. To overcome this problem, β-1,3-glucan, biotechnologically derived polysaccharide, has been proposed as a joining agent to combine granular ceramics into novel compact and elastic composite. Hydroxyapatite/glucan elastic material was processed and evaluated as a potential bone void filler.MethodologyThe procedure of composite formation was based on gelling properties of glucan. Its properties were studied using X-ray microtomography, SEM-EDS, FTIR spectroscopy, compression test and ultrasonic method. Sorption index was determined in phosphate buffered saline; bioactivity in simulated body fluid; sterility in growth broth and human blood plasma; implantation procedure in dog model.ResultsHAp/glucan composite is sterilizable, flexible and self-adapting to defect shape. It exhibits bioactivity, good surgical handiness, high sorption index and profitable mechanical properties, resembling those of spongy bone. Results of pilot clinical experiment on animal (dog) patients of a local clinic of animal surgery suggested good healing properties of the composite and its transformation into new bone tissue within critical-size defect.ConclusionsThe results obtained in this study confirm that flexible HAp/glucan composite has potential as a bone-substituting material. Promising results of pilot clinical experiment suggest that further in vivo experiments should be performed.

Ultrasonication as a Method of Investigation of the Mechanical Properties of Doped Hafnium Barium Titanate

The purpose of this study was to fabricate dense ceramic specimens from the system of BaTiO3-BaHfO3 and then to perform mechanical tests. The effect of Hf content on a microstructure and mechanical properties of the BaTiO3-BaHfO3 solid solution was investigated at room temperature. To determine the elastic constants (the Young′s modulus E, the shear modulus G, bulk modulus K and the Poisson′s ratio v) of BaHfxTi1-xO3 a method of measurement of the longitudinal (VL ) and transverse (VT ) ultrasonic wave velocities for this type of material was developed.

An ultrasonic through-transmission technique for monitoring the setting of injectable calcium phosphate cement.

An ultrasound through-transmission method to monitor the setting process of injectable calcium phosphate bone cements in body fluids is presented. This method can be used to determine the acoustic properties of the bone cement as it sets, which are linked to its material properties and provide some information about changes occurring within the cement. The development of the methodology of ultrasonic testing and execution of velocity measurements of the longitudinal and transverse waves using the through-transmission method made it possible to determine the material constants of samples during the setting and hardening process of an injectable cement paste in physiological fluids (i.e. the Youngs modulus (E), the Poisson ratio (ν) and the shear modulus (G)), and to determine the degree of anisotropy of wave velocity in the samples. A strong advantage of the proposed method is that it is non-destructive, and the same sample can be used to monitor the whole process of the cement setting. The testing was performed on premixed and injectable calcium phosphate (CPC)/chitosan blend, where glycerol was used as a liquid phase. Comparisons between ultrasonic velocity and empirical tests such as compressive strength, porosity measurement, FTIR, SEM and XRD analysis at different days of immersion in Ringers solutions showed that the ultrasonic velocity can be very useful to provide in situ information about changes occurring within the cement.

Physical Properties of Ba0.95Pb0.05TiO3+0.1%Co2O3

The single-phase perovskite structure of the Ba0.95Pb0.05TiO3+0.1%Co2O3 ceramics was confirmed by the X-ray diffraction method. Microstructural studies revealed that the samples were of good quality and chemically homogeneous. The thermal behaviour of ceramics was studied using the in situ high-temperature X-ray synchrotron powder diffraction investigation. The energy gap of about 3.2 eV was estimated using a reflectance spectroscopy. Measurements showed the influence of Pb and Co on the character of phase transition in the BaTiO3 structure. The results were compared to the ones obtained for pure BaTiO3.

The effects of the additive of Eu ions on elastic and electric properties of BaTiO3 ceramics

ABSTRACT The BaTiO3 and BaTiO3+X%wt.Eu2O3 (X = 1, 2, 3) ceramics were prepared by a solid phase reaction. The structural and morphology studies were carried out by means of an X-ray diffraction technique and scanning electron microscopy, respectively. Elastic moduli were determined with the use of an ultrasonic method. The dielectric permittivity (ϵ′) and tanδ as a function of composition and temperature were investigated. The increasing concentration of Eu ions leads to a slight shift of the Curie temperature and changes the characteristics of ϵ′ and tanδ. The structural, mechanical and dielectric properties of the BTEX ceramics were discussed in terms of microstructure and dopants contents.

Composition-related structural, thermal and mechanical properties of Ba1−xSrxTiO3 ceramics (0 ≤ x ≤ 0.4)

The Ba1−xSrxTiO3 (BST) ceramics were prepared by conventional ceramic method. The crystalline structure and morphology were studied by X-ray diffraction and scanning electron microscopy, respectively. Experimental results show that increase of sintering temperature leads to an uncontrolled precipitating of the phase with a lower content of Ti. The dielectric constant and specific heat as a function of composition and temperature were investigated. The increasing concentration of Sr ions leads to a shift of the Curie point below room temperature. To determine the elastic constants (the Youngs modulus E, the shear modulus G and the Poissons ratio v) of BST, a method of measurement of the longitudinal (νL) and transverse (νT) ultrasonic wave velocities for this type of material was developed. The structural, dielectric and mechanical properties of BST ceramics were discussed in terms of microstructure and chemical composition

Methodology for determining material constants of anisotropic materials belonging to the transversely isotropic system by ultrasound method

The paper presents the methodology and results of the ultrasound determination of material constants of anisotropic materials belonging to the transversely isotropic system. Ultrasound through-transmission method was used for determining material constants. Based on the measurements of velocities of longitudinal and transverse ultrasounds waves propagation, respectively polarized in required directions all the elastic and the material constant of the test materials were determined. Measurements of all the velocities necessary to determine the elastic constants were performed on a specially prepared individual samples. The tests were carried out on porous polycrystalline anisotropic graphites of anisotropy in Youngs modulus of up to 26% and Al2O3 composites with up to 30% of hBN causing anisotropy of Youngs modulus of up to 50%. It was found that for all tested samples the value of Youngs modules and modules stiffness decreasing with increasing porosity in the graphites and increasing content of hBN in Al2O3.

Investigation of mechanical and electrical properties of Li doped sodium niobate ceramic system

ABSTRACT The Na0.96Li0.04NbO3 ceramic solid solution was prepared by means of a two-stage hot-pressing technology. The X-ray diffraction analysis showed the formation of a single perovskite phase with an orthorhombic symmetry in the investigated composition. The microstructure and EDS measurements were performed. They confirmed the high purity and the expected qualitative composition. A good homogeneity of the microstructures and a small degree of porosity were observed. The elastic modulus (the Youngs modulus E, shear modulus G, and Poissons ratio ν) of Na0.96Li0.04NbO3 were determined with the use of an ultrasonic method. The electrical properties of Na0.96Li0.04NbO3 ceramics were investigated at the frequency ranging from 0.5 kHz to 200 kHz, and the temperature ranging from room temperature to 750 K. The test sample shows a dielectric dispersion.

Physical properties and microstructure characteristics of (1–x)BaTiO3–xCaTiO3 systems

ABSTRACT The study investigates the microstructure, thermal and mechanical properties of (1–x)BaTiO3–xCaTiO3 ((1–x)BT–xCT)) (x = 0.01, 0.04, 0.08) samples. The BT–CT system to be tested was formed as a solid solution of BT and CT and testing was done on fractured sections of the ceramic. Its thermal properties were investigated using the Differential Scanning Calorimeter (DSC), dielectric measurements were taken based on CT content and frequency data in a wide temperature range. Elastic properties of the samples were examined to determine how the actual CT content and the material microstructure should affect the mechanical properties of the investigated material. Parameters calculated for all samples included the Young’s modulus (E), the shear modulus (G), bulk modulus (K), and Poisson ratio (ν), calculated on the basis of longitudinal and transverse wave velocities. Unlike neat BT samples, (1–x)BT–xCT systems exhibit shifts of phase transition temperatures, improved homogeneity, and feature increased dielectric constant and elasticity modulus. The study aims to identify the underlying causes and origins of this behaviour.

The Uniaxial Pressure Dependence of Dielectric Properties of Na0.5K0.5(Nb0.96Sb0.04)O3+0.5mol%MnO2 Ceramics

The behavior of the electric permittivity and polarization of Na0.5K0.5(Nb0.96Sb0.04)O3+0.5mol%MnO2 ceramics as a function of uniaxial pressure (0 – 600 bar) applied perpendicularly to the ac electric field were investigated. The application of a uniaxial pressure causes a reduction of the peak intensity of the electric permittivity (ɛ) and change of the phase transition from first order to second one. The temperature dependence of electric permittivity ɛ shows that the Curie temperature increases with increasing pressure and presents a broadening and flattening of the maximum of ɛ(T). The obtained results suggested an appearance of the dielectric relaxation near the phase transition temperature which strongly coupled with strain induced by the pressure. The effect of uniaxial pressure have an effect on the dynamics of the perovskite lattice.