Full Research Paper
Nano-Biomaterials
Shekufe Borhan; Saeed Hesaraki
Volume 6, Issue 3 , June 2012, Pages 163-168
Abstract
Bioactive glasses with different compositions have been extensively used as substitute for defective bones. Injectable biomaterial is important in clinical applications that involve defects with limited accessibility or when using minimally invasive surgical techniques. In this study bioactive glass ...
Read More
Bioactive glasses with different compositions have been extensively used as substitute for defective bones. Injectable biomaterial is important in clinical applications that involve defects with limited accessibility or when using minimally invasive surgical techniques. In this study bioactive glass nano-powder was synthesized by acid-base catalyzed sol-gel process and used as solid phase of injectable non-setting pastes. Morphological characteristics of powder were found by TEM. To prepare paste the powder was mixed with hyaluronic acid and polyvinyl alcohol solutions. Stability of pastes was determined by soaking in simulated body fluid. Rheological behaviours of paste in both rotation and oscillation modes were also measured. The results showed that particle size of glass powder was 20-30 nm. According to rheometry, these nano composites exhibited non-Newtonian shear thinning behaviour. By adding polyvinyl alcohol more stable paste with increased hysteresis loop area is obtained. The oscillatory tests revealed that these pastes were viscoelastic with more elastic character. The biocomposite can potentially be used as bioactive paste for the treatment of hard and even soft tissues.
Full Research Paper
Biomimetics
Behzad Seyfi; Hosein Mansourinejad; Bahman Vahidi; Nasser Fatouraee
Volume 6, Issue 3 , June 2012, Pages 169-175
Abstract
Peristaltic flow is one of the important mechanisms of fluid transmission. In addition to the divers engineering applications, this mechanism plays an important role in biological organs such as digestion system and urine excretion. In this paper, urine bolus transportation in ureter has been investigated ...
Read More
Peristaltic flow is one of the important mechanisms of fluid transmission. In addition to the divers engineering applications, this mechanism plays an important role in biological organs such as digestion system and urine excretion. In this paper, urine bolus transportation in ureter has been investigated experimentally using a peristaltic flow simulator apparatus. Some of the features of this apparatus worth mentioning are its ability to use it to investigate the influence of some important parameters in peristaltic flow, such as the effect of pressure difference between the kidney and the bladder on the quantity of discharge and reflux rates, effect of the mean velocity of bolus transport on discharge rate, existence of fluid film and its effect on bolus discharge rate, and effect of fluid bolus length on reflux rate. Then we compare the obtained results with the similar theoretical studies. It was observed that an increase in the pressure difference between inlet and outlet decreases the ratio of reflux to initial volume of the bolus, and it increases the discharge rate. Moreover, the quantities of reflux and discharge rate decrease by decreasing the bolus transport velocity. It was also observed that the thickness of the fluid film has an inverse relation with respect to the discharge rate and with increasing the bolus length reflux is increasing.
Full Research Paper
Nano-Biomaterials
Zeynab Fereshteh; Mohammad Hossein Fathi; Reza Mozaffarinia
Volume 6, Issue 3 , June 2012, Pages 177-193
Abstract
The aim of this study was to prepare and characterize the novel poly (ε-caprolactone) / Mg-doped fluorapatite nanoparticles (PCL / nMg-FA) composite scaffolds by electrospinning method. The optimized composite was achieved by changing of electrospinning parameters such as solvent, polymer concentration, ...
Read More
The aim of this study was to prepare and characterize the novel poly (ε-caprolactone) / Mg-doped fluorapatite nanoparticles (PCL / nMg-FA) composite scaffolds by electrospinning method. The optimized composite was achieved by changing of electrospinning parameters such as solvent, polymer concentration, applied voltage, nozzle to collector distance and content of ceramic. It was shown that the diameter size of fibers decreased by adjusting the viscosity and conductivity solution. Optimal samples were studied with transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA). According to TEM and the X-ray maps of the scaffolds, Mg-FA particles were homogeneously dispersed into the nanofibers without any agglomeration. It is noteworthy that was not any surfactant in this study. Also results of XRD show no chemical reactions between polymeric solution components. Mechanical properties of the scaffolds were also evaluated. Results showed that tensional strength of scaffolds and also thermal stability increased by increasing the weight ratio of nanoparticles up to 5 wt. %.
Full Research Paper
Biomedical Image Processing / Medical Image Processing
Alireza Rahimpour; Abbas Nasiraei Moghaddam
Volume 6, Issue 3 , June 2012, Pages 195-205
Abstract
Nowadays eye gaze tracking has wide range of applications in human computer interaction. One of these applications is using trajectory of eye gaze instead of foot or hand for disabled people to execute some commands. Various methods have been proposed, some of this methods can successfully track the ...
Read More
Nowadays eye gaze tracking has wide range of applications in human computer interaction. One of these applications is using trajectory of eye gaze instead of foot or hand for disabled people to execute some commands. Various methods have been proposed, some of this methods can successfully track the eye gaze. However, they always require specific circumstances, training or are not capable of real-time performance. In this paper, we proposed a framework to track eye gaze in real-time by using a simple and low cost webcam mounted on ordinary laptops. This process widely exploits the weighted normalized correlation function in an adaptive template matching approach. The implemented system tracks the face and also extracts some eye features such as iris position, eye corners and sclera region in eyes, in real time. These features are used in eye gaze estimation. Also the influence of illumination changes, background alterations, different faces and face movements is minimized as much as possible. The implemented gaze tracking system is able to control the motions of mouse cursor and click on an onscreen keyboard in real time.
Full Research Paper
Biomedical Image Processing / Medical Image Processing
Amin Mohammadian; Hasan Aghaeinia; Farzad Towhidkhah
Volume 6, Issue 3 , June 2012, Pages 207-218
Abstract
In this paper, a method is proposed based on the prior knowledge from a new subject to improve the performance of person-independent facial expression recognition. First, in order to obtain a basic system, a combination of geometric features and texture descriptor is compared with global features (i.e., ...
Read More
In this paper, a method is proposed based on the prior knowledge from a new subject to improve the performance of person-independent facial expression recognition. First, in order to obtain a basic system, a combination of geometric features and texture descriptor is compared with global features (i.e., mapped face images using the Kernel-PCA and raw data of face images). The results of comparison under noisy conditions were investigated and evaluated by person-dependent/independent cross-validation method. The obtained basic system was evaluated by leave-one-subject-out cross-validation. Since the same subjects are not introduced in both training and test phases, the basic recognition system is person-independent and its performance is substantially lower than that of person-dependent cross-validation case. To improve the performance of the basic system, a method is proposed in which virtual samples are generated based on the prior knowledge from the new subject and are used in learning process. The results show that the recognition rate increases up to 96% for the person-dependent basic system, kernel-PCA method is more sensitive than the others to interpersonal variability, and the recognition rate is significantly (P<0.05) improved up to 91.39% compared to that of person-independent case.
Full Research Paper
Speech processing
Ehsan Akafi; Mansour Vali; Negin Moradi
Volume 6, Issue 3 , June 2012, Pages 119-129
Abstract
Hypernasality is a frequently occurring resonance disorder in children with cleft palate. Generally an operation is necessary to reduce the hypernasality and therefore an assessment of hypernasality is imperative to quantify the effect of the surgery and design the speech therapy sessions which are crucial ...
Read More
Hypernasality is a frequently occurring resonance disorder in children with cleft palate. Generally an operation is necessary to reduce the hypernasality and therefore an assessment of hypernasality is imperative to quantify the effect of the surgery and design the speech therapy sessions which are crucial after surgery. In this study, a new quantitative method is proposed to estimate hypernasality. The proposed method used the fact that an Autoregressive (AR) model for vocal tract system of a patient with hypernasal speech is not accurate; because of the zeros appear in the frequency response of vocal tract system due to existence of extra channel between oral and nasal cavity of these patients. Therefore in our method hypernasality was estimated by a quantity calculated from comparing the distance between the sequences of cepstrum coefficients extracted from AR model and Autoregressive Moving Average (ARMA) model. K-means and Bayes theorem were utilized for finding a threshold value for proposed index to classify the utterances of subjects. We achieved the balanced accuracy up to 82.18% on utterances and 97.72% on subjects. Since the proposed method needs only computer processing of speech data, compare to other clinical methods it is provides a simple evaluation of hypernasality.
Full Research Paper
Vida Khalili; Jafar Khalil Allafi; Hosein Maleki Ghaleh
Volume 6, Issue 3 , June 2012, Pages 231-238
Abstract
In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized ...
Read More
In this study, a hydroxyapatite/carbon nanotubes composite was coated at room temperature on NiTi shape memory alloy (SMA) through electrochemical deposition using stable suspension which was prepared by adding 4 g natural hydroxyapatite powder and 1 wt. % CNTs to 50 ml n-butanol. Suspension was stabilized using triethylenamine as dispersant. Surface characteristics, adhesion strength, stability and bioactivity of the composite coating were subsequently studied. EDX examination of the composite coating surface revealed homogeneous dispersion of carbon nanotubes all over coating. Also, the bonding strength of composite coating was found to be about 24 MPa. Compared to NiTi sample coated with hydroxyapatite and coated with hydroxyapatite/carbon nanotubes, the bode and nyquist plots of NiTi samples with hydroxyapatite/carbon nanotubes composite coating suggested that the composite coating was chemically more stable and provided corrosion resistance for NiTi SMA. In-vitro bioactivity test in SBF showed that the presence of CNTs in HA/CNTs composite coating does not have negative effect on ability of apatite formation.
