Prediction of hexagonal lattice parameters of stoichiometric and non-stoichiometric apatites by artificial neural networks

Download

index.pdf

Date

2009

Author

Koçkan, Ümit

Metadata

Show full item record

Item Usage Stats

253
views

116
downloads

Apatite group of minerals have been widely used in applications like detoxification of wastes, disposal of nuclear wastes and energy applications in addition to biomedical applications like bone repair, substitution, and coatings for metal implants due to its resemblance to the mineral part of the bone and teeth. X-ray diffraction patterns of bone are similar to mineral apatites such as hydroxyapatite and fluorapatite. Formation and physicochemical properties of apatites can be understood better by computer modeling. For this reason, lattice parameters of possible apatite compounds (A10(BO4)6C2), constituted by A: Na+, Ca2+, Ba2+, Cd2+, Pb2+, Sr2+, Mn2+, Zn2+, Eu2+, Nd3+, La3+, Y3+; B: As+5, Cr+5, P5+, V5+, Si+4; and C: F-, Cl-, OH-, Br-1 were predicted from their elemental ionic radii by artificial neural networks techniques. Using artificial neural network techniques, prediction models of lattice parameters a, c and hexagonal lattice volumes were developed. Various learning methods, neuron numbers and activation functions were used to predict lattice parameters of apatites. Best results were obtained with Bayesian regularization method with four neurons in the hidden layer with ‘tansig’ activation function and one neuron in the output layer with ‘purelin’ function. Accuracy of prediction was higher than 98% for the training dataset and average errors for outputs were less than 1% for dataset with multiple substitutions and different ionic charges at each site. Non-stoichiometric apatites were predicted with decreased accuracy. Formulas were derived by using ionic radii of apatites for lattice parameters a and c.

Subject Keywords

Nanotechnology., Engineering., Apatite.

URI

http://etd.lib.metu.edu.tr/upload/12610311/index.pdf
https://hdl.handle.net/11511/18360

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Enhancement of mechanical properties of co-doped hydroxyapatite coatings on pre-treated Ti6Al4V Hacıoğlu, Tuğçe; Evis, Zafer; Tezcaner, Ayşen (2017-10-27) Titanium and its alloys are commonly preferred implant materials for hard tissue applications. Today more than 4.4 million people have an internal fixation device and over 1.3 million people possess an artificial joint. Not only is there high demand for orthopedic surgeries for new patients every year, but there is also an even higher demand for patients who must receive revision surgeries. In order to enhance the properties of titanium based implant materials, different pretreatment and coating techniques ...
Modeling of spherulite microstructures in semicrystalline polymers Oktay, H. Emre; Gürses, Ercan (2015-11-01) Semicrystalline polymers are composed of crystalline structures together with amorphous polymer chain networks and therefore they exhibit deformation mechanisms of both crystalline materials and amorphous polymers. One of the most common microstructures observed in semicrystalline polymers is the spherulite microstructure in which crystalline lamellae are embedded in a matrix of amorphous material and grow out from a common central nucleus in radial directions. The mechanical behavior of semicrystalline pol...
Modeling and application of artificial muscle actuators Çamlıca, Fahri Buğra; Ünlüsoy, Yavuz Samim; Department of Mechanical Engineering (2019) Electro Active Polymers (EAPs) are the group of polymeric materials which are also known as the Artificial Muscles that are already available commercially or can be manufactured in laboratory conditions. Artificial muscle actuators are considered as alternatives to conventional electric/pneumatic/hydraulic devices in certain applications which require lightweight actuators. Artificial muscle actuators are not yet capable of completing heavy duty missions, however these flexible actuators do not require addi...
Investigation of tensile strength of hydroxyapatite with various porosities by diametral strength test Evis, Zafer (2008-04-01) It is appropriate to administer the diametral test to biomedical materials used in dental applications because stresses formed on dental implants are similar to those that formed in this test. To show this similarity, an experimental study of diametral strength testing of hydroxyapatite was performed. The influence of porosity on hydroxyapatite was investigated experimentally to determine how the diametral strength was affected. Hydroxyapatite was air sintered at 1100 degrees C for 1 h with porosities rangi...
Synthesis and Characterization of Zirconium based Bulk Amorphous Alloys Saltoğlu, İlkay; Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (2005-09-28) In recent years, bulk amorphous alloys and nanocrystalline materials have been synthesized in a number of ferrous and non-ferrous based alloys systems, which have gained some applications due to their unique physico-chemical and mechanical properties. In the last decade, Zr-based alloys with a wide supercooled liquid region and excellent glass forming ability have been discovered. These systems have promising application fields due to their mechanical properties; high tensile strength, high fracture toughne...

Citation Formats

Ü. Koçkan, “Prediction of hexagonal lattice parameters of stoichiometric and non-stoichiometric apatites by artificial neural networks,” M.S. - Master of Science, Middle East Technical University, 2009.