Piezoelectric Composites Based on Hydroxyapatite / Barium Titanate

2008 ◽  
Vol 54 ◽  
pp. 1-6 ◽  
Author(s):  
Chris R. Bowen ◽  
K.V.S. Raman ◽  
Vitaly Yu. Topolov
Keyword(s):  
Volume Fraction ◽  
Active Material ◽  
Ferroelectric Ceramic ◽  
Ceramic Composites ◽  
Batio3 Ceramic ◽  
Physical Factors ◽  
Electromechanical Properties ◽  
Modified Model ◽  
Perovskite Type

This paper reports experimental and modelling results on the manufacture and properties of hydroxyapatite / BaTiO3 ceramic composites and studies their electromechanical properties with ferroelectric ceramic volume fractions, mFC ³ 0.7. In these composites the bio-active properties of hydroxyapatite are combined with the electromechanical properties of a perovskite-type ferroelectric BaTiO3 ceramic in an attempt to create a novel polarised bone-substitute material. Experimental results of the volume fraction dependences of the effective piezoelectric coefficients * 31 d (mFC), * 33 d (mFC) and dielectric permittivity e *s 33 (mFC) of stress free samples are analysed within the framework of a modified model of a porous piezo-active material that is described in terms of 1–3 (one-dimensional rods in a continuous matrix) and 2–2 connectivity (laminates). The role of several structural elements and physical factors in forming the electromechanical properties of the composites is discussed. It is shown that performance of these materials typical properties are 5 pC / N < | * 31 d |< 45 pC / N, 20 pC / N < * 33 d < 100 pC / N and 400 < e *s 33 / 0 e < 1300.

scholarly journals Effect of the matrix subsystem on hydrostatic parameters of a novel 1–3-type piezo-composite

2015 ◽  
Vol 08 (05) ◽  
pp. 1550049 ◽  
Author(s):  
Vitaly Yu. Topolov ◽  
Christopher R. Bowen ◽  
Paolo Bisegna ◽  
Anatoly E. Panich
Keyword(s):  
Elastic Properties ◽  
Electromechanical Coupling ◽  
Volume Fraction ◽  
Electromechanical Coupling Factor ◽  
Ferroelectric Ceramic ◽  
Coupling Factor ◽  
Polyurethane Composite ◽  
The Matrix ◽  
Type Composite

The influence of the aspect ratio and volume fraction of ferroelectric ceramic inclusions in a 0–3 matrix on the hydrostatic parameters of a three-component 1–3-type composite is studied to demonstrate the important role of the elastic properties of the two-component matrix on the composite performance. Differences in the elastic properties of the 0–3 matrix and single-crystal rods lead to a considerable dependence of the hydrostatic response of the composite on the anisotropy of the matrix elastic properties. The performance of a 1–0–3 0.92 Pb ( Zn 1/3 Nb 2/3) O 3–0.08 PbTiO 3 SC/modified PbTiO 3 ceramic/polyurethane composite suggests that this composite system is of interest for hydroacoustic applications due to its high hydrostatic piezoelectric coefficients [Formula: see text] and [Formula: see text], squared figure of merit [Formula: see text], and electromechanical coupling factor [Formula: see text].

scholarly journals Modelling of Creep in Alloys Strengthened by Rod-Shaped Particles: Al-Cu-Mg Age-Hardenable Alloys

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 930 ◽  
Author(s):  
Chiara Paoletti ◽  
Michael Regev ◽  
Stefano Spigarelli
Keyword(s):  
Grain Size ◽  
Volume Fraction ◽  
Coarse Grained ◽  
Creep Model ◽  
Modified Model ◽  
Physically Based ◽  
Excellent Description ◽  
The Difference ◽  
Temperature Exposure

In recent years, a creep model that does not involve adjustable parameters has been successfully applied to coarse-grained aluminum. The main feature of this model is that it is fully predictable. On the other hand, in the case of age-hardenable alloys, any physically-based creep model should take into account the changes in the volume fraction, size and distribution of strengthening precipitates, and the effect of grain size. With this aim in view, in this paper, the original model previously applied to single phase-alloys has been modified to describe the effects of the grain size and of the consequences of the high-temperature exposure on the strengthening role of precipitates. To this end, phenomenological equations describing the coarsening phenomena and their dependence on the applied stress have been introduced. The modified model has given an excellent description of the experimental behavior of an AA2024-T3 alloy tested at 250 and 315 °C and has provided a sound explanation of the difference observed when comparing the minimum creep rate obtained using two different testing techniques.

3D Model of Crack Propagation in Particulate Ceramic Composite Containing Residual Stresses

2017 ◽  
Vol 754 ◽  
pp. 103-106
Author(s):  
Kateřina Štegnerová ◽  
Zdeněk Majer ◽  
Pavel Hutař ◽  
Luboš Náhlík
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composite ◽  
Volume Fraction ◽  
Numerical Models ◽  
Ceramic Composites ◽  
Fe Method ◽  
Critical Crack ◽  
Alumina Particles

A crack propagation and fracture behaviour of particulate ceramic composite were investigated. Influence of 3D shape of particles on the crack propagation was studied together with influence of the presence of residual stresses, which are developed inside the composite during manufacturing process. Finite element (FE) method was used for numerical simulation of propagating crack in the composite. Basic numerical models of low-temperature co-fired ceramics (LTCC) with alumina particles homogenously dispersed in the glass matrix were developed. Volume fraction of alumina phase was 20vol.%, which is typical amount for LTCC. The results show that existence of residual stresses retards the crack propagating under conditions of sub-critical crack growth (SCG). Presented results contribute to a better understanding of the role of residual stresses in particulate ceramic composites.

scholarly journals The emerging role of mechanical and topographical factors in the development and treatment of nervous system disorders: dark and light sides of the force

2021 ◽  
Author(s):  
Natalia Bryniarska-Kubiak ◽  
Andrzej Kubiak ◽  
Małgorzata Lekka ◽  
Agnieszka Basta-Kaim
Keyword(s):  
Nervous System ◽  
Physical Factors ◽  
Nervous System Diseases ◽  
Therapeutic Approaches ◽  
System Disease ◽  
New Therapeutic Approaches ◽  
The Subject ◽  
Topographical Factors ◽  
New Treatment

AbstractNervous system diseases are the subject of intensive research due to their association with high mortality rates and their potential to cause irreversible disability. Most studies focus on targeting the biological factors related to disease pathogenesis, e.g. use of recombinant activator of plasminogen in the treatment of stroke. Nevertheless, multiple diseases such as Parkinson’s disease and Alzheimer’s disease still lack successful treatment. Recently, evidence has indicated that physical factors such as the mechanical properties of cells and tissue and topography play a crucial role in homeostasis as well as disease progression. This review aims to depict these factors’ roles in the progression of nervous system diseases and consequently discusses the possibility of new therapeutic approaches. The literature is reviewed to provide a deeper understanding of the roles played by physical factors in nervous system disease development to aid in the design of promising new treatment approaches. Graphic abstract

scholarly journals Microstructure and magnetic properties of Nd-Fe-B-(Re, Ti) alloys

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 29-33
Author(s):  
Mariusz Hasiak
Keyword(s):  
Magnetic Properties ◽  
Phase Composition ◽  
Volume Fraction ◽  
Magnetic Characteristics ◽  
Ti Alloys ◽  
Wide Range ◽  
Magnetically Hard ◽  
Ti Addition ◽  
Microstructure And Magnetic Properties

Abstract The microstructure and magnetic properties of nanocomposite hard magnetic Nd-Fe-B-(Re, Ti) materials with different Nd and Fe contents are studied. The role of Re and Ti addition in phase composition and volume fraction of the Nd-Fe-B phase is determined. All samples are annealed at the same temperature of 993 K for 10 min. Mössbauer spectroscopy shows that the addition of 4 at.% of Re to the Nd8Fe78B14 alloy leads to creation of an ineligible amount of the magnetically hard Nd2Fe14B phase. Moreover, the microstructure and magnetic characteristics recorded in a wide range of temperatures for the Nd8Fe79−xB13Mx (x = 4; M = Re or Ti) alloys are also analyzed.

Role of Pristine and Acid-Functionalized Fullerene on Breaking Dye Aggregates and its Impact on the Efficiency of Solar Cells

2014 ◽  
Vol 67 (5) ◽  
pp. 819
Author(s):  
Syed Mujtaba Shah ◽  
Zafar Iqbal ◽  
Muzaffar Iqbal ◽  
Naila Shahzad ◽  
Amina Hana ◽  
...  
Keyword(s):  
Solar Cells ◽  
Zno Nanoparticles ◽  
Self Assembly ◽  
Zno Nanorods ◽  
Active Material ◽  
Dye Sensitized Solar Cells ◽  
Dye Sensitized ◽  
Transmission Electron ◽  
Sensitized Solar Cells

Porphyrin dyes have an inherent tendency to aggregate. This leads to a self-quenching phenomenon that hinders electron transfer to the conduction band of semiconductors in dye-sensitized solar cells. Self-quenching adversely affects the efficiency of solar cells. Here, we report the interaction of porphyrin with pristine and acid-functionalized fullerene molecules on the surface of ZnO nanoparticles under chemisorbed conditions. Chemisorption of porphyrin only on ZnO nanoparticles instigates aggregation of the porphyrin molecules. These aggregates can be effectively broken by chemisorbing fullerene molecules on the surface of the ZnO nanoparticles. This is due to self-assembly formation processes because of porphyrin–fullerene interactions. The nanohybrid material, consisting of ZnO nanorods, acid-functionalized porphyrin, and fullerene derivatives, was characterized by UV–visible spectroscopy, fourier transform infrared spectroscopy, fluorescence spectroscopy, and transmission electron microscopy. The material generates better performing dye-sensitized solar cells when compared with those fabricated from porphyrin-based photo-active material.

The role of physical factors in the complex therapy of patients with rheumatoid arthritis

1985 ◽  
Vol 66 (4) ◽  
pp. 318-318
Author(s):  
L. V. Chernetsova ◽  
A. G. Ibragimova
Keyword(s):  
Rheumatoid Arthritis ◽  
Comparative Analysis ◽  
Drug Therapy ◽  
Electromagnetic Waves ◽  
Physical Factors ◽  
Complex Therapy ◽  
Decimeter Range

The comparative analysis of treatment of 76 patients with rheumatoid arthritis using electromagnetic waves of the decimeter range and lithium electrophoresis, depending on the activity of the process and the type of drug therapy.

Sign in / Sign up

Export Citation Format

Share Document