Finite element modeling of electrospun nanofibre mesh using microstructure architecture analysis

This investigation is aimed at modeling the tensile behavior of electrospun polyurethane (PU) membrane. The PU web is produced with different morphologies and the structural parameters are studied through SEM images. Three-dimensional network is simulated using ABAQUS software. Each fibre is modeled as hyperelastic material and each crosslink is modeled as multi point constrain tie. The stress-strain behavior of PU mat is modeled by finite element method, and the effect of fibre diameter, fibre orientation and thickness of web is investigated. The stress–strain curves of networks at three different morphologies are compared with modeling measurements. The model by using third order reduced polynominal as fibre hyperelastic potential energy function shows good agreement with experimental findings which confirm that the tensile behavior of PU web can be explained entirely by microstructure of the network

A novel honey-based nanofibrous scaffold for wound dressing application

In this study, nanofiber meshes were produced from aqueous mixtures of poly(vinyl alcohol) (PVA) and honey via electrospinning. The Electrospinning process was performed at different PVAs to honey ratios (100/0, 90/10, 80/20, 70/30, and 60/40). Dexamethasone sodium phosphate was selected as an anti-inflammatory drug and incorporated in the electrospinning solutions. Its release behavior was determined. Uniform and smooth nanofibers were formed, independent of the honey content. In case honey content increased up to 40%, some spindle-like beads on the fibers were observed. The diameter of electrospun fibers decreased as the ratio of honey increased. The release characteristics of the model drug from both the PVA and PVA/honey (80/20) nanofibrous mats were studied and statistical analysis was performed. All electrospun fibers exhibited a large initial burst release at a short time after incubation. The release profile was similar for both PVA and PVA/honey (80/20) drug-loaded nanofibers. This study shows that an anti-inflammatory drug can be released during the initial stages and honey can be used as a natural antibiotic to improve the wound dressing efficiency and increase the healing rate

Brain Volume Estimation Enhancement by Morphological Image Processing Tools

Background: Volume estimation of brain is important for many neurological applications. It is necessary in measuring brain growth and changes in brain in normal/ abnormal patients. Thus, accurate brain volume measurement is very important. Magnetic resonance imaging (MRI) is the method of choice for volume quantification due to excellent levels of image resolution and between-tissue contrast. Stereology method is a good method for estimating volume but it requires to segment enough MRI slices and have a good resolution. In this study, it is desired to enhance stereology method for volume estimation of brain using less MRI slices with less resolution. Methods: In this study, a program for calculating volume using stereology method has been introduced. After morphologic method, dilation was applied and the stereology method enhanced. For the evaluation of this method, we used T1-wighted MR images from digital phantom in BrainWeb which had ground truth. Results: The volume of 20 normal brain extracted from BrainWeb, was calculated. The volumes of white matter, gray matter and cerebrospinal fluid with given dimension were estimated correctly. Volume calculation from Stereology method in different cases was made. In three cases, Root Mean Square Error (RMSE) was measured. Case I with T=5, d=5, Case II with T=10, D=10 and Case III with T=20, d=20 (T=slice thickness, d=resolution as stereology parameters). By comparing these results of two methods, it is obvious that RMSE values for our proposed method are smaller than Stereology method. Conclusion: Using morphological operation, dilation allows to enhance the estimation volume method, Stereology. In the case with less MRI slices and less test points, this method works much better compared to Stereology method

Finite element modeling of electrospun nanofibre mesh using microstructure architecture analysis

83-88This investigation is aimed at modeling the tensile behavior of electrospun polyurethane (PU) membrane. The PU web is produced with different morphologies and the structural parameters are studied through SEM images. Three-dimensional network is simulated using ABAQUS software. Each fibre is modeled as hyperelastic material and each crosslink is modeled as multi point constrain tie. The stress-strain behavior of PU mat is modeled by finite element method, and the effect of fibre diameter, fibre orientation and thickness of web is investigated. The stress–strain curves of networks at three different morphologies are compared with modeling measurements. The model by using third order reduced polynominal as fibre hyperelastic potential energy function shows good agreement with experimental findings which confirm that the tensile behavior of PU web can be explained entirely by microstructure of the network

Identification and S-genotyping of Novel S-alleles in Wild Species of Pyrus Genus

The Pyrus species exhibit the gametophytic self -incompatibility which is considered to be the most widespread self-incompatibility system among flowering plants. This system prevents self-fertilization through a specific pollen-pistil recognition mechanism. The S-allele diversity in the Iranian genotypes indicates that the pear germplasm of Iran can be an excellent source of variability for breeding programs. In this study, the S-RNases of 64 pear cultivars and wild genotypes of Pyrus species of Iran and Europe including Pyrus communis, Pyrus salicifolia, Pyrus syriaca and Pyrus ussuriensis were amplified using consensus and allele-specific primers by PCR-based method. This method was used for the detection of product size characteristics of the 23 S-RNases (S101-S125) and revealed the existence of one new allele named S127 and the footprint of S8 of P. pyrifolia syn. P. serotina in Iranian genotypes. Interestingly, in 6 specimens allele PcS127 is coupled with PpS8, suggesting that these plants might come from subgroups or populations where the contribution of P.  Pyrifolia syn. P. serotina is more consistent. The pool of S-RNases found in the Iranian germplasm had a different composition from the European cultivars, and showed traces of significant genetic contribution from other species. Also, application of this approach in 21 European cultivars allowed re-evaluation of alleles of Veerdi (S101/S104) and Conseiller a la Coeur (S103/S123/S105)

Chloroplast genome diversity of the Pyrus genus; from Iranian and European wild pear species to the cultivated cultivars.

The genome structure of chloroplast DNA (cpDNA) is highly conserved among the different species belonging to the Pyrus genus. In spite of the relevance of this genetic material for phylogenesis because of its maternal inheritance, molecular data on these species are very scanty. In order to investigate phylogenetic relationship in the genus Pyrus, we recognized three hyper variable regions in intergenic spacers of cpDNA of 73 Iranian and European pear (Pyrus communis L.) local cultivars and wild genotypes, plus 9 Japanese pear genotypes (Pyrus pyrifolia, syn. P. serotina) and one Chinese pear (P. × bretschneideri). CAPS markers were developed by digesting PCR products separately with 3 restriction enzymes and the relative patterns were used for a cluster analysis. Results evidenced that Iranian and European pear cultivars were divided into five groups, whereas Japanese pear cultivars were grouped together with Iranian pear genotypes. This evidence supports the hypothesis of a significant genetic contribution in the Iranian wild genotypes from Japanese pear, brought to this region in ancient times through the main routes of the Silk Road

Contribution of Western and Eastern species to the Iranian pear germplasm revealed by the characterization of S-genotypes.

Iran is recognized as an important source of genetic diversity of pear germplasm including native and introduced species. It is located in the Mid-Asian, center of diversification of the genus Pyrus, where several species have originated; moreover, the Silk Road historically favoured an intense exchange of cultivated crops and agricultural technologies during the course of trade and cultural transmission between ancient China and central/West Asia. Thus, Iran is maybe one of the first places where specimens of Pyrus communis imported from Europe could have come into contact with Pyrus pyrifolia, syn. P. serotina genotypes coming from eastern Asian countries. Moreover, pear species exhibit the S-RNase-based gametophytic self-incompatibility system that prevents self-fertilization thus forcing out-crossing. Since there is no major barrier for hybridization in Pyrus, several different species might have contributed to the makeup of the Iranian traditional germplasm. The characterization of self-incompatibility ribonucleases in Iranian P. communis cultivars and landrace genotypes revealed that, in addition to the pool of alleles previously detected in European cultivars, the Iranian germplasm shows the presence of alleles most likely introduced via hybridization with cultivated or wild Pyrus species