Abstract: The effects of iron content, fiber length, and stability of carbon nanotube (CNT) suspension on cells were examined. Five kinds of single-wall carbon nanotube (SWCNT) suspensions were prepared: with catalytic iron, without iron, long SWCNTs (stable), short SWCNTs (stable), and short SWCNT (unstable). These suspensions were applied to A549, THP-1, and mouse peritoneal macrophage cells. After a 24-h exposure, the mitochondrial activity, cell membrane damage, intracellular oxidative stress, and expression of cytokine genes were determined. Among these properties of SWCNTs, stability of CNT suspension had the most influence on the cells, whereas the effects of iron content and fiber length were small. The unstable SWCNT suspension caused a substantial increase in intracellular ROS levels. Additionally, the cellular effects of stable multi-wall carbon nanotubes (MWCNTs) were examined. The MWCNT suspension did not show any cellular effects. Overall, influences of CNT suspension on mitochondrial activity and cell membrane damage were small. These results suggest that the physical properties of CNT suspension are important factors for their cellular effects. Thus, CNT suspensions prepared with the same material but having different physical properties would differ in the cellular effects they exert, including cytotoxicity. Therefore, physical characterization of CNT suspensions is essential to the evaluation of CNT toxicity. In particular, stability of CNT suspension notably influenced the intracellular ROS level.
Abstract: Central nerve system degeneration is a crucial problem for many patients. To use an in situ hydrogel formation is an attractive method to treat that problem. An in situ hydrogel was developed for central nerve system regeneration. An acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the shark skin of the brownbanded bamboo shark (Chiloscyllium punctatum) were used to produce hybridized hydrogels by the biomimetic approach. Collagen was mixed with methylcellulose and used 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as a crosslinker. The hydrogels had various ratios of collagen:methylcellulose: 100:0, 70:30, 50:50, 30:70, and 0:100. Structural, molecular, and morphological organization were characterized and observed by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The DSC results showed that the peak of denatured collagen fibril shifted higher in a 30:70 ratio of collagen:methylcellulose in both ASC and PSC. The FT-IR results indicated that the structure of hydrogels from both ASC and PSC were organized into complex structures. The SEM results demonstrated that the collagen fibril networks were formed in both ASC and PSC hydrogels. The results indicated that the samples containing collagen promise to be an in situ hydrogel for central nerve regeneration.
Abstract: Since articular cartilage is avascular, both nutrient supply and metabolic waste excretion depend on diffusion. However, the major cause of the progression of articular cartilage defect is the poor inherent regenerative capacity of chondrocytes which limits the process of cartilage tissue repair. Creation of nutrient gradients in in vitro cell culture, however, can provide a clue on zonal distributions of cells and glycosaminoglycan synthesis throughout the tissue engineered cartilage. We hypothesized that glucose gradient, in combination with growth factors, could induce differences in matrix distributions for articular cartilage regeneration. Chondrocytes were harvested from bovine cartilage and expanded in monolayers. First, either p0 or p2 chondrocytes were differentiated in serum-free chondrogenic medium containing different glucose concentrations supplemented with TGFβ3/dex or IGF-1under hypoxic or normoxic conditions for 7 days in monolayer. The results indicate that cellular metabolism, cell numbers and glycosaminoglycan (GAG) content increased with increase in glucose concentration in all conditions. Aggrecan (AGC) expression consistently increased with decreasing glucose concentration in both normoxic and hypoxic conditions. COL II and COL I expressions increased with increasing glucose concentration up to 5mmol/L. The expression of COMP increased with increasing glucose concentration under hypoxic conditions and interestingly showed an opposite trend under normoxic conditions. However, comparing the chondrogenic capacity of p0 and p2 cells in the different glucose concentrations did not show differences, but the potential of p2 cells was in general lower compared to p0. Hypoxia had stimulatory effects on matrix production compared to normoxia in both passages. Therefore, supplemented glucose concentration in monolayer could induce differences in matrix production, but the chondrogenic potential remained equal. Therefore, this information could be use to a create gradients through a tissue-engineered cartilage.
Abstract: Malaria is characterized by its life-threatening and destructive capability through the cause of widespread sufferings, contributing to the increase in mortality rates throughout the various parts of the world. Since the needs for immediate and appropriate diagnosis of malaria are urgently needed, this paper proposes a procedure for colour image segmentation that has been utilized using the malaria images of P. vivax species. First, the malaria images are enhanced by using modified global contrast stretching technique. Then, cascaded moving k-means and fuzzy c-means clustering is applied in order to segment the infected cell from its blood cells background. In this study, a new colour component namely modified B-Y component is proposed as a modified version of the original B-Y component of C-Y colour model. By using modified B-Y component, the colour properties of the infected cell component will be utilized for stained object identification in malaria image. The proposed colour component is compared to intensity, R-Y and B-Y components for identifying the component of colour that provides the best segmentation result. Finally, median filter and region growing algorithms are applied for smoothing the segmented image and removing any unwanted regions from the image, respectively. The proposed segmentation method has been applied and tested on 100 malaria images. The results indicate that segmentation using the proposed modified B-Y component has produced the best segmentation results with segmentation accuracy, sensitivity and specificity values of 99.37%, 88.22% and 99.82%, respectively.
Abstract: The main purpose of the present work is to determine the optimum gradation direction of an endodontic prefabricated parallel post (EPPP) made of functionally graded material (FGM). To determine the optimum gradation direction of an EPPP made of FGM, the finite element method (FEM) is used. After that, the optimization technique was adopted in order to determine the optimum material gradient for the functionally graded endodontic prefabricated parallel post (FGEPPP). Simulation results indicated that, the optimum gradation direction for the FGEPPP is from up to down, and can be described by using a modified sigmoid function. The effect of varying of the material gradient indexes on the performance of the (FGEPPP) is investigated. Also, stress distributions in all of FGEPPP cases and in homogeneous EPPP case are investigated. The current investigation shows that, the use of the FGM improves the performance of an EPPP.
Abstract: Thermography information of foot is playing very important role in body character and related products design. The purpose of this study is to investigate the distribution and change character of foot skin temperature variety during low-intensity movement. Totally 19 subjects participated in this testing, skin surface temperature monitor was using high-precision Infrared Thermal Imager. The average foot skin temperature existed a significant difference at rest condition. After 30min persistent low-intensity exercise, each area of the foot was increased, and the increasing trend was quite similar. This study could provide the basis of foot physiological function understanding.
Abstract: In this paper, inverse kinematic analysis of a proposed three link mechanism of a bio-inspired micro scanning device towed underwater by a surface vessel to actuate its aileron fins for its depth control and for its stabilization against roll is performed. Mechanism is actuated by IPMC actuators. To speed up the design verification process, computer aided simulations are used to perform motion analysis of the proposed IPMC actuated mechanism through Pro/Mechanism tool. Inverse kinematic analysis is performed to find out the joint variables of the mechanism to realize fin actuation along desired path. Displacements, velocities and accelerations of the links constructing mechanism are found out to establish their interrelationship. Results are analysed for the study of mechanism efficacy and for sizing the IPMC actuators. This paper contributes to introduce a new approach of virtual prototyping using advanced simulation tools for analysis and design verification of IPMC actuated mechanisms for biomimetic applications before moving into functional prototype stage.
Abstract: In this paper, a methodology is presented to perform dynamic analysis of structural linked mechanisms under true actuation cycle and force response of applied IPMC actuators. Dynamic analysis of a three link mechanism for fin actuation of a micro fish like device, towed by a surface vessel through tow cable, is performed through this methodology and same is applicable to other biomimetic robotic applications. Fluid (water) exerts a torque on IPMC actuated fin which is a function of fin's deflection and fluid flow velocity. Dynamic analysis is performed to assess the performance and efficacy of fin actuation mechanism under different loading conditions in terms of fin's deflection, velocity and acceleration. Actuation force is increased by increasing number of applied IPMC actuators of known actuation cycle and force generation response. Applied torque is determined by performing a numerical simulation of IPMC actuated fin against different flow velocities through two-way fluid structure interaction (FSI) approach. Numerical simulation is performed in ANSYS WORKBENCH to capture the complex hydrodynamic interactions between fin and fluid. Effect of increased actuation force against constant flow velocity (towing speed) and of increased flow velocity against constant actuation force are evaluated in terms of fin's deflection, velocity and acceleration. Finally, consequence of increasing the length of the link, connecting IPMC actuators and fin, are appraised for same actuation force and applied torque. Dynamic analysis is performed in Pro/ Mechanism, an advanced simulation tool. A technique of virtual prototyping through simulations is applied to access the performance of the fin actuation mechanism under true loading scenario before going into experimental phase, saving cost and time
Abstract: IPMC is used as artificial muscle in bioinspired micro structures/devices due to its low voltage actuation, high bending deformation, rapid response and capability to be operated in aqueous environment. In this paper, deflection analysis of IPMC actuated fin of a micro fish like device is presented to find out angle of attacks generated by IPMC deflection under different voltages applied to it. A novel approach is presented to perform motion analysis of IPMC actuated mechanisms for biomimetic robots under true actuation presentation of the IPMC actuator. This paper also contributes to present velocity and acceleration of the actuator at different voltages. Finally, two different configurations of the fin actuation mechanism are characterized in terms of angle of attack produced by them under same actuation responses of an IPMC actuator. Deflection analysis is performed in Pro/ Mechanism, an advanced simulation tool. A technique of virtual prototyping through simulations is applied to access the performance of both configurations of the fin actuation mechanism under true scenario before going into manufacturing.