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The purpose of this research is to introduce and design scaffolds composed of polycaprolactone(PCL) and gelatine nanofibers containing both hydroxyapatite and graphene nanoparticles at the same time for using in bone tissue engineering. At first, optimal conditions for the production of PCL/gelatine nanofibrous webs were investigated. In the following step, hydroxyapatite and graphene nanoparticles incorporated into PCL/gelatine nanofibrous webs for comparison with PCL/gelatine nanofibrous webs without adding any particles. Morphological, mechanical and biological tests were done to analyse fabricated structures. 50%PCL/50%gelatin sample has the less fiber diameter in both group with or without adding nanoparticles of hydroxyapatite and graphene. The FTIR analyses revealed characteristic absorption bands for PCL/gelatin/hydroxyapatite/graphene nanofibrous scaffolds is still similar to that of PCL/gelatin sample. Also, blending of PCL with gelatin decreased tensile strength and increased the tensile strain. As the final result, the addition of hydroxyapatite and graphene reduces diameter of nanofiber and improves the biological and mechanical properties and has a good potential using in bone tissue engineering. [ABSTRACT FROM AUTHOR]

The aim of this study is to classify ring-spun yarns according to their unevenness, imperfections, and hairiness parameters using cluster analysis. The mentioned features of ring-spun yarns are measured for five different ranks. Five ranks of ring-spun yarns including compact and conventional as well as combed and carded types are chosen and produced. In the modeling section, the model-based clustering method was applied as a strong method based on the distribution of each variable. In order to select the best fit and to find out the final clustering, bayesian information criterion (BIC) is applied. According to the results of modeling, five ranks of selected ring-spun yarns are classified in four clusters and the acceptable agreement is measured according to Cohen's kappa method. The highest value for Kappa represents a high agreement to match between the clustering result and the real rank. [ABSTRACT FROM AUTHOR]

The present research is focused on optimization the buckling process factors to produce buckled silk yarn using the Analytic Hierarchy Process (AHP) method to gain the best mechanical properties. To achieve this aim, the improvement of mechanical performance is investigated by surface changes of single yarns due to air-jet buckling process. SEM images of yarns approved the efficiency of buckling process by increasing the yarn diameter. According to the decision matrix, the best conditions of buckling process were related to 40 Psi as air pressure and 80 rpm as speed. In the following step, multi-twisted buckled silk yarn was designed and compared in load at break aspect with native collagenous tissues. To sum up, buckling process and also analytic hierarchy process optimization method are the acceptable approaches to design the best structure of multi-twisted buckled silk yarn that has a good potential as a scaffold in collagenous tissues. [ABSTRACT FROM AUTHOR]

The aim of this study is to gain the best structure of Poly (3-hydroxybutyrate) (PHB)/chitosan electrospun aligned and random fibrous scaffold for nerve tissue engineering applications using electrospinning method, morphologically and biologically. The results illustrated that by addition of chitosan, surface porosity percentages have increased while the water contact angle has decreased, for both structures. Results of biodegradation rate noted that aligned PHB/chitosan fibrous scaffolds had a slower degradation rate than random PHB/chitosan fibrous scaffolds. Finally, cultivation results of rat neuronal-like cells (B65 cell line) on electrospun-aligned and random fibrous scaffolds were compared. Results of MTT assay demonstrated better improvement for the proliferation of B65 cells on electrospun-aligned PHB/chitosan scaffolds. Also, SEM images indicated that the bi-polar neurite extensions and the orientation of nerve cells were aligned in the direction of the fibre alignment. [ABSTRACT FROM AUTHOR]

Electroactive actuators including materials or devices can respond to an electric field, current, or voltage with a corresponding change in their size or shape. Recent researches show an emerging interest in the electroactive polymers actuating systems because of their proper electrochemical properties for actuators and artificial muscles. The current research involves fabrication of core–sheath polyacrylonitrile (PAN)–polyaniline (PANi) nanofibers containing up to 15% TiO2 nanoparticles in core, as well as the investigation of the mechanical and electrochemical properties of the prepared nanofibrous bundles. In the first step, high electrical conductive PANi polymer was synthesized through the oxidative polymerization method. TiO2 nanoparticles were added to the core of nanofibers to improve both mechanical and electrical properties of the produced nanofibrous bundles. Synthesized PANi was used to produce aligned nanofibrous bundles comprising PAN–TiO2 (0–15%) as core and PAN–PANi as sheath with an average diameter of 199–350 nm. The structural and physical properties of nanofibrous bundles were studied by Fourier-transform infrared, scanning electron microscopy, and transmission electron microscopy techniques. Mechanical and cyclic voltammetric tests were performed on core–sheath PAN/PANi samples to evaluate the mechanical and electrochemical properties, respectively. According to the results, fabricated bundles of coaxial PAN–TiO2/ PAN–PANi nanofibers is highly recommended as a candidate for electroactive actuator because of high electrical conductivity. PAN/ PAN–PANi nanofibers demonstrate an oxidation/ reduction peak of 0.8 V with a maximum current of 14.0 × 10−5 A related to PANi and PAN–TiO2(10%)/ PAN–PANi has a maximum current of 11.0 × 10−5 A with a peak at 0.8 V because of the presence of PANi. [ABSTRACT FROM AUTHOR]

Finite element method can provide valuable results and information to evaluate and assess the mechanical behavior of tissue engineered scaffolds. In this investigation, a structurally and analytically based model is applied to analyze and to describe the mechanical properties of wire rope yarns as scaffold or other applications in textile engineering. In order to modeling the mechanical behavior of single yarn, non-linear hyperfoam model with three strain energy potential has been used. The results of finite element model are compared with an experimental approach and showed good agreement between software and experimental analysis with a maximum error at break of about 4.3%. As a result, validation of the finite element method is guaranteed for analysis of other structure of multi twisted yarn or wire ropes. [ABSTRACT FROM AUTHOR]

In this investigation, a nanofibrous scaffold was fabricated through electrospinning of polycaprolactone (PCL) and chitosan (CS) using a novel collector to make better orientation and pore size for cell infiltration. PCL/CS nanofibers with 90-rpm collector speed and 40° angle between collector wires of the new collector have fewer diameters with better pore, size and nanofibers orientation. Mechanical properties, roughness parameters, topology, structure, hydrophilicity, and cell growing were considered for liver tissue engineering. The cell culture was done using epithelial liver mouse cells. The developed electrospun PCL/CS scaffold using novel collector would be an excellent matrix for biomedical applications especially liver tissue engineering. [ABSTRACT FROM PUBLISHER]

A genetic algorithm model has been developed to determine the optimal parameters of mechanical aspects of a silk wire-rope scaffold with the highest predictive accuracy and generalized ability simultaneously. The study pioneered on employing a genetic algorithm (GA) to optimize the parameters of scaffold in tendon and ligament tissue engineering. Experimental results show that the GA model performs the best predictive accuracy to imply mechanical behavior with native values successfully. [ABSTRACT FROM AUTHOR]

In tissue engineering, proper mechanical property is one of the key subjects for modeling tendon and ligament scaffolds. In this research, attempts were made to determine the factors of structural parameters of wire-rope silk scaffolds by using the intelligent neural network method to find optimum mechanical behavior for tendon and ligament regeneration. Experimental design of wire-rope scaffolds was made according to Taguchi orthogonal method. The input structural parameters were the number of filament and twist in each layer in four levels wire-rope and output was determined by an index that was defined according to mechanical properties of anterior cruciate ligament for young age group. Finally, a back-propagation neural network with a high accuracy was designed to predict the mechanical properties of wire-rope tendon and ligament scaffold and according to sensitivity analysis, the number of filaments and twist in outer layers is less important than other input parameters. Finally, a multiple linear regression, a most widely used statistical method, developed from the data. [ABSTRACT FROM AUTHOR]