Simulation of the thermally induced austenitic phase transition in NiTi nanoparticles

The reverse martensitic ("austenitic") transformation upon heating of equiatomic nickel-titanium nanoparticles with diameters between 4 and 17 nm is analyzed by means of molecular-dynamics simulations with a semi-empirical model potential. After constructing an appropriate order parameter to distinguish locally between the monoclinic B19' at low and the cubic B2 structure at high temperatures, the process of the phase transition is visualized. This shows a heterogeneous nucleation of austenite at the surface of the particles, which propagates to the interior by plane sliding, explaining a difference in austenite start and end temperatures. Their absolute values and dependence on particle diameter are obtained and related to calculations of the surface induced size dependence of the difference in free energy between austenite and martensite.Comment: 6 pages, 4 figures, accepted for publication in "The European Physical Journal B

Developing a game-based mobile application to enhance reading skills for dyslexic students at primary schools in Saudi Arabia

Fluent reading is necessary for any future learning, regardless of discipline. However, dyslexia is a universal reading impairment in which each individual with dyslexia has a set of fundamental reading difficulties that make this fluency challenging to achieve. Human-Computer Interaction (HCI) interventions have become more prevalent in the last couple of decades in addressing dyslexia, where they have been presented to students to help overcome their difficulties. Thus, this thesis presents a novel game-based mobile application that has been designed and developed to increase reading skills for dyslexic students at primary schools in Saudi Arabia. This thesis evaluates the effectiveness of the proposed application by conducting two studies in primary schools in Saudi Arabia. From the studies’ findings, it can be seen that the proposed game-based mobile application aids in improving reading skills for dyslexic students. Additionally, the studies showed very positive behaviours towards the proposed mobile application, leading to a high level of satisfaction. Thus, it is considered a supportive tool to enhance students with dyslexia to overcome their reading difficulties and effectively promote the learning process. This work has provided key contributions, including the creation of the novel educational application for dyslexic students learning Arabic and a distinct evaluation approach and methodology

EFFECT OF ANODIC OXIDATION ON THE CORROSION BEHAVIOR OF NICKEL-TITANIUM SHAPE MEMORY ALLOYS IN SIMULATED BODY FLUIDS (SBF)

The effect of anodic oxidation of a NiTi shape memory alloy in sulfuric acid electrolyte on its surface characteristics was studied. Surface roughness was measured by roughness tester. Surface morphology was studied using optical microscopy (OM) and scanning electron microscopy (SEM). Corrosion behavior was specified by recording Potentiodynamic polarization curves and measuring the content of Ni ions, released into a SBF solution using atomic absorption spectroscopy (AAS). Fourier transformation infrared radiation (FT-IR) and energy dispersive spectroscopy were employed to verify the biocompatibility of the anodized and bare alloys after submersion in SBF. It was shown that anodic oxidation in sulfuric acid significantly increases corrosion resistance and biocompatibility. This layer improves corrosion resistance and Ni ion-release resistance by impeding the direct contact of the alloy with the corrosion mediums i.e. Ringer and SBF solutions. The TiO2 oxide layer also decreases the releasing of Ni ions in to SBF solutio

Superior multifunctional polypyrrole anticorrosion coating modified by polydopamine decorated barium titanate nanoparticles on NiTi shape memory alloys

The enhancement of corrosion protection capabilities through the use of conducting polymer coatings has become a necessity in order to safeguard metallic materials for biomedical purposes. In the present study, the hydroxylated barium titanate nanoparticles (BT-OH) were functionalized with polydopamine (PDA) to promote the dispersion of nanoparticles in a polypyrrole (PPy) matrix. The TEM analysis confirmed the formation of the PDA layer on the BT nanoparticles (BT NPs). Then, PPy coating was successfully electropolymerized on NiTi alloy in the presence of various concentrations (1, 3, 5, and 10 wt %) of PDA functionalized BT (PBT). The morphology, structure, and topography of PPy and composite coatings were investigated utilizing the field emission scanning electron microscope (FESEM), Fourier transforms infrared spectroscopy (FTIR), and atomic force microscope (AFM). Surface morphology analysis exhibited that the augmentation of the PBT nanoparticles changed it from cauliflower-like for PPy to nodular-like for composite coatings. Nano-indentation evaluations of the coatings have demonstrated that the hardness and elastic modulus of composite-coated NiTi was raised favorably by PBT enhancement, reaching 0.86 ∓ 0.2 (GPa) and 16.06 ∓ 3.23 (GPa) in PPy with 5 wt % PBT (PPy/5PBT), respectively. Electrochemical examinations demonstrated that PPy/5PBT coating revealed superb corrosion protection in Ringer solution, serving as a physical barrier and preventing the pitting corrosion of NiTi alloy. Finally, the constructive effect of PBT inclusion in the PPy coating on the corrosion performance of NiTi substrate was authenticated by lower Ni ion release from composite-coated NiTi compared with PPy coating

Effect of aging and solution annealing on transformation and deformation mechanism of super-elastic Ni50.9%-Ti alloy in nano- scale

Effects of aging and solution annealing treatment on the super elastic respond of the cold-worked Ni50.9%-Ti thin wire was studied in nano-scale utilizing instrumented nanoindentation. The nanoindentation results were coupled with the tensile test results to provide better insight to the governing deformation mechanisms. The first applied heat treatment consisted of solution annealing treatment (850°C for 60 minutes) followed by aging at 450°C for 30 minutes and as second heat treatment the cold-worked wire was aged at 450°C for 30 minutes with no prior solution annealing treatment. Both tensile test and nanoindentation results showed better super elastic behavior for the wire subjected to second treatment. Indentation displacement bursts were observed in loading course after both treatments. However, slope changes in unloading course of indents were recorded after second heat treatment which might be due to reverse phase transformation. Surface asperities on the post-indented surface after first treatment were observed far away from indentation stress field by atomic force microscopy

Bone Cancer Detection and Classification Using Owl Search Algorithm With Deep Learning on X-Ray Images

Bone cancer is treated as a severe health problem, and, in many cases, it causes patient death. Early detection of bone cancer is efficient in reducing the spread of malignant cells and decreasing mortality. Since the manual detection process is a laborious task, it is needed to design an automated system to classify and identify the cancerous bone and the healthy bone. Therefore, this article develops an Owl Search Algorithm with a Deep Learning-Driven Bone Cancer Detection and Classification (OSADL-BCDC) technique. The OSADL-BCDC algorithm follows the principle of transfer learning with a hyperparameter tuning strategy for bone cancer detection. The OSADL-BCDC model employs Inception v3 as a pretrained model for the feature extraction process which does not necessitate a manual segmentation of X-ray images. Besides, the OSA is applied as a hyperparameter optimizer for enhancing the efficacy of the Inception v3 method. Finally, the long short-term memory (LSTM) approach is used for identifying the presence of bone cancer. The proposed OSADL-BCDC technique reduces diagnosis time and achieves faster convergence. The experimental analysis of the OSADL-BCDC algorithm is tested using a set of medical images and the outcomes were measured under different aspects. The comparison study highlighted the improved performance of the OSADL-BCDC model over existing algorithms