Soltani-Jigheh H.,Shahid Madani University of Azarbaijan |
Asadzadeh M.,Islamic Azad University at Zanjan |
Marefat V.,Bonab University
Turkish Journal of Engineering and Environmental Sciences | Year: 2013
Some important engineering characteristics of compacted clay liners can be adversely affected by desiccation cracking, resulting in the loss of effectiveness and integrity of containment systems as a barrier. Recently, there has been interest in using tire chips as an additive material to prevent desiccation cracking. In this study, compaction, shrinkage, and desiccation cracking tests were performed to study the effect of tire chips on suppressing shrinkage and desiccation cracks in clayey soils. The percentages of tire chips used were 10%, 20%, and 30% by weight. The results of shrinkage tests indicate that the percentage of volume change of the specimens decreases with addition of tire chips and its value also is affected by size of the tire chips. The intensity of cracks diminishes in the clay-tire mixtures so that the observed crack reduction in the range of used tire chips content is about 40% to 80%. The optimum tire chips content also is necessary to achieve maximum crack reduction and minimum shrinkage strain, while maintaining acceptable hydraulic conductivity. This study suggests the potential application of waste tires to suppress desiccation cracks encountered in landfill clay liners. © TÜUBIITAK.
PubMed | Bonab University, National University of Singapore and Amirkabir University of Technology
Type: | Journal: Carbohydrate polymers | Year: 2016
Nanofibrous nerve guides have gained huge interest in supporting the peripheral nerve regeneration due to their abilities to simulate the topography, mechanical, biological and extracellular matrix morphology of native tissue. Gum tragacanth (GT) is a biocompatible mixture of polysaccharides that has been used in biomedical applications. During this study, we fabricated aligned and random nanofibers from poly(l-lactic acid) and gum tragacanth (PLLA/GT) in various ratios (100:0, 75:25, and 50:50) by electrospinning. Scanning electron microscope demonstrated smooth and uniform nanofibers with diameters in the range of 73365nm and 22673nm for align PLLA and random PLLA/GT 50:50 nanofibers, respectively. FTIR analysis, contact angle, in vitro biodegradation and tensile measurements were carried out to evaluate the chemical and mechanical properties of the different scaffolds. PLLA/GT 75:25 exhibited the most balanced properties compared to other scaffolds and was used for in vitro culture of nerve cells (PC12) to assess the potential of using these scaffolds as a substrate for nerve regeneration. The cells were found to attach and proliferate on aligned PLLA/GT 75:25 scaffolds, expressing bi-polar neurite extensions and the orientation of nerve cells was along the direction of the fiber alignment. Results of 8 days of in vitro culture of PC12 cells on aligned PLLA/GT 75:25 nanofibers, showed 20% increase in cell proliferation compared to PLLA/GT 75:25 random nanofibers. PLLA/GT 75:25 aligned nanofibers acted as a favorable cue to support neurite outgrowth and nerve cell elongation compared with PLLA nanofibers. Our results showed that aligned PLLA/GT 75:25 nanofibers are promising substrates for application as bioengineered grafts for nerve tissue regeneration.
Vahidifar A.,Isfahan University of Technology |
Khorasani S.N.,Isfahan University of Technology |
Park C.B.,University of Toronto |
Khonakdar H.A.,Leibniz Institute of Polymer Research |
And 4 more authors.
RSC Advances | Year: 2016
A closed cell rubber foam, based on a natural rubber (NR)/nanoclay nanocomposite, was produced using a one-step foaming process with compression molding. The effects of three different nanoclays on the properties of the NR/nanoclay nanocomposite foam were examined: an un-modified nanoclay (Cloisite Na+) and two organo-modified nanoclays (Cloisite 20A and Cloisite 30B). We examined their curing behavior, foam morphology, sound absorption, and their mechanical and thermal properties. The morphological results from X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) showed that the Cloisite Na+ agglomerated in the NR matrix while an intercalated-exfoliated/fully-exfoliated morphology was seen in the Cloisite 30B and the Cloisite 20A, respectively. The rheometry results showed that all three nanoclay types increased the NR's curing rate, and also accelerated its scorch and curing time. Other results showed that the organo-modified nanoclays, which were the ammonium-salt modified nanoclays (Cloisite 30B and Cloisite 20A), improved the foam's curing behavior more than the pristine Cloisite Na+. Using the one-step foaming process kept the nanocomposite foam density and expansion ratio constant in all of the samples, independent of the nanoclay type. Meanwhile, the scanning electron microscopy (SEM) results showed that the nanoclay increased the cell density and decreased the cell size, depending on the nanoclay type. The mechanical properties of NR nanocomposite foams including the hardness and the modulus were improved by incorporating the nanoclays. At the same time, there was a gradual deterioration in the foams' sound absorption and thermal stability behavior. © 2016 The Royal Society of Chemistry.
Fallah M.,Amirkabir University of Technology |
Bahrami S.H.,Amirkabir University of Technology |
Ranjbar-Mohammadi M.,Bonab University
Journal of Industrial Textiles | Year: 2016
Phytochemicals have been used over the centuries in order to cure various diseases and still do to this day. Phytochemicals are herbal extracts that are also named herbal remedies. Curcumin (CUR), which is a natural polyphenolic compound derived from the roots of the plant Curcuma Longa, has many therapeutic properties. CUR has poor water solubility and instability that has confined its further applications, thus there is need for a carrier to deliver the drug consistently. In this research, the feasibility of using polycaprolactone/gelatin nanofibers as carriers for CUR is examined. Nanofibers are obtained by electrospinning method. The morphology of nanofibers was observed by scanning electron microscopy. Fourier Transform Infrared Spectroscopy and differential scanning calorimetry is used to study the thermal behavior of the nanofibers. Antibacterial tests were conducted against methicillin-resistant staphylococcus aureus (MRSA) and extended spectrum β lactamase (ESBL). These pathogens are very dangerous and versatile pathogens emerging rapidly causing nosocomial infections in hospitals. The nanofibers were 99.9% antibacterial against MRSA and 82.56% against ESBL. The results showed that these nanofibers have potent antibacterial activity against both Gram positive and Gram negative bacteria. As a result, these nanofibers are very promising materials for antibacterial applications. © 2015, © The Author(s) 2015.
Mokhtari H.,Bu - Ali Sina University |
Esmaeili F.,University of Tabriz |
Dabbagh-Yarishah J.,Bonab University
Transactions of the Indian Institute of Metals | Year: 2016
In this study, the effects of electrode clamping force on the fatigue strength of 5083-0 aluminum alloy spot-welded joints have been investigated via experimental and multiaxial fatigue analysis. To do so, three sets of the specimens—with different amounts of the sheet spacing—which have been fabricated using different values of the electrode clamping force, were selected, and then fatigue tests were performed under various cyclic longitudinal load levels. A nonlinear finite element code was used to obtain the stress and strain distribution near the roots of the nuggets as a result of longitudinal applied loads. Fatigue lives of the specimens were estimated with Crossland, Kandil–Brown–Miller, Glinka, Varvani-Farahani, Fatemi–Socie, and Smith–Watson–Topper multiaxial fatigue criteria by means of the local stress and strain distribution obtained from the finite element analysis. It was shown that, the fatigue lives of spot-welded joints were improved by increasing the electrode clamping force. Also, the comparison between experimental results and multiaxial fatigue predictions revealed that among the applied criteria, the Crossland and Glinka approaches had the best accuracy for all types of the specimens. © 2016 The Indian Institute of Metals - IIM
Abbasbandy S.,Imam Khomeini International University |
Hashemi M.S.,Imam Khomeini International University |
Hashemi M.S.,Bonab University
Engineering Analysis with Boundary Elements | Year: 2011
In this paper, we consider the Cauchy problem for the Laplace equation by group preserving scheme (GPS) which is an ill-posed problem, because the solution does not depend continuously on the data. For this, the Laplace equation, by using a semi-discretization method namely method of line, is converted to an ODEs system and then obtained ODEs system is considered by GPS. Stability of GPS for ill-posed Laplace equation is shown. The problem numerical results show the efficiency and power of this method. © 2011 Elsevier Ltd. All rights reserved.
Rahimi F.,Bonab University |
Roberts A.C.,Northwestern University |
Jog M.,London Health Sciences Center
Clinical Neurology and Neurosurgery | Year: 2016
Objectives Freezing of gait (FoG) is a challenging clinical symptom in Parkinson's disease with variable improvements in FoG with rasagiline. In this prospective, uncontrolled, pre-/post- treatment pilot study, we explore the clinical variables that contribute to this variability and those that predict improvement. Patients and methods Frequency and duration of FoG, along with other standardized scales, were evaluated in 18 optimally medicated PD participants with intractable FoG, prior to and after completion of a 90-day course of 1 mg daily rasagiline. Gait tasks were video-recorded and analyzed by two independent reviewers. After evaluating the simple main effect, hierarchical cluster analysis was used to identify subgroups for treatment responsiveness. Bidirectional elimination stepwise regression analysis was conducted to identify which clinical variables predicted reduction in frequency of FoG events post-treatment. Results There were no overall pre-/post- treatment improvements, a result driven by a heterogeneous response to treatment. Three subgroups were identified: improved (n = 6) with a 136% and 162% reduction in FoG count and duration; worsened (n = 5) with 154% and 141% increase in FoG count and duration; and no change (n = 3). The final predictive model had good explanatory power (adjusted-R2 = 0.9898, p < 0.01), explaining 99% of the variance between the improved and worsened groups. In this model, lower UPDRS gait scores, higher LEDD dose, lower anxiety scores, lower FOG-Q scores, and higher UPDRS scores for lower extremity rigidity and rise from chair, predicted FoG-related rasagiline benefit. Conclusion Using both objective and subjective measures for FoG, the current pilot study identified a set of clinical variables that may elucidate the heterogeneous FoG-responsiveness following rasagiline treatment and aid in predicting improvement. © 2016 Elsevier B.V.
Majidabad S.S.,Bonab University |
Shandiz H.T.,Shahrood University of Technology |
Control Engineering and Applied Informatics | Year: 2015
This paper presents two novel fast converging robust controllers for Caputo derivative based fractional-order nonlinear systems. These fractional-order systems are high-relative-degree with model uncertainties and external disturbances. First, a new fractional-order model is derived from the original model based on block transformation strategy. Employing the block transformation technique makes the highrelative- degree systems versatile for sliding mode controllers design. In the second step, two different nonlinear sliding manifolds are proposed to reach a short time convergence. Subsequently, appropriate nonlinear sliding mode control laws are developed to assure the robustness and fast converging behaviors. It is worthy to notify that the mentioned sliding manifolds guarantee the fractional-order system last state convergence, and the other states convergence can be assured by control gains of the block transformation. The stability of closed-loop system for both controllers is achieved by the fractionalorder stability theorems. Finally, two comprehensive numerical simulations are carried out to indicate the superiority and effectiveness of the suggested robust controllers.
Delghavi M.B.,Bonab University |
Shoja-Majidabad S.,Bonab University |
Yazdani A.,Ryerson University
IEEE Transactions on Sustainable Energy | Year: 2016
This paper proposes a voltage control strategy for islanded operation of dispatchable electronically coupled distributed energy resource (DER) systems, for remote (off grid) electrification systems. The proposed control strategy is based on fractional-order sliding-mode control, offers black-start functionality, maintains the quality of the output voltage of the host DER system in spite of unbalanced and/or distorted load currents, and ensures protection of the power-electronic interface to external faults. Moreover, the fractional derivative order of the controller can be used as an additional tuning parameter. Performance of the proposed control strategy is demonstrated through time-domain simulation of single-and multi-DER islanded networks, starting from black-start and subjected to various operating scenario, and it is also compared to the performance of a proportional-integral (PI)-based control strategy. © 2016 IEEE.
Irani G.N.H.,Bonab University |
Tawosi V.,Bonab University
2011 5th International Conference on Application of Information and Communication Technologies, AICT 2011 | Year: 2011
All Information Systems (IS) need an Authentication and Authorization (AA) System for security of their different modules. Existing Enterprise Systems, Frameworks and Portals use a similar centralized approach. In this paper, a new decentralized architecture has provided for AA in Modular Information Systems. To obtain this aim, firstly, all existing approaches and their disadvantages for AA, has been investigated and categorized. Secondly, to obtain a new architecture and solving disadvantages, new AA principles has been developed using robust object oriented principles and heuristics. New architecture has been developed based on these obtained AA principles. In addition, the new architecture decreases the Core complexity and distributes that into modules. Also the new architecture has maximum quality of reusability and extensibility and modifiability that can be applied to all Modular Information Systems. © 2011 IEEE.