In this study, silk fibroin was extracted from cocoons of silkworms and fabricated into nonwoven mats by electrospinning method. A new model based on the group method of data handling (GMDH) and artificial neural network (ANN) was developed for estimation of the average diameter of electrospun silk fibroin nanofibers. In this regard, concentration, flow rate, voltage, distance, and speed of collector were used as input parameters and average diameter of the fibers was considered as output parameter. Two models were capable to estimate average diameter of fibers with good accuracy. The average absolute relative deviation for GMDH and ANN models was equal to 3.56 and 2.28 %, respectively. Furthermore, due to importance of oxygen delivery to site of injury to promote wound healing, continuity equation for mass transport was employed for prediction of oxygen profile in the system containing wound dressing and skin. The result showed that our prepared wound dressing is capable to pass the oxygen completely to the skin layer and is not acting as a barrier for oxygen delivery to wound site. Since average nanofibers diameter can influence the mat physical, mechanical and biological properties then this model may serve as a useful guide to obtain tailor made and uniform silk nanofibers at various combinations of process variables.

Background and Aim: The aim of this study was to evaluate the effect of glass-fiber on the flexural strength of composite resins.Methods & Materials: The study was done experimentally in which flexural strength of glass - fiber reinforced composite resins were assessed with a three-point load test on 22 samples. 11 samples of composite resin blocks and 11 samples of composite resins reinforced with glass- fiber were prepared in a mold of 25x6x2mm and stored in 100% of moisture for one month, until they were ready for testing in an Instron Universal Testing Machine using a crosshead speed of 1 mm/min. Student t test was used for statistical analysis.Result: Flexural strength in the first group was 22.39±3.38 MPa and in second group was 29.74±2.36 MPa. According to t test analysis, the difference between the two groups was statistically significant. (P<0.01).Conclusion: The results of this study suggest that the flexural strength of the fiber-reinforced composite made from glass - fibers was more than composite resin.

Due to the proven performance of fibrous insulations in various industries, including manufacturing, energy, aerospace, and construction industries. These insulations were studied in several papers. Ceramic tiles used on the space shuttle are one of the most famous high temperature applications of these fibrous insulation. Due to high porosity of these insulations, the main method of heat transfer in these materials is radiation, especially when heat transfer occurred in more than 500 degrees of Celsius. Anomalous Diffraction Theory (ADT) is one of the theoretical methods to estimate extinction coefficient of fiber insulation. Roseland theory calculates the radiation heat transfer coefficient according to the radiation extinction coefficient. Results obtained from the developed code were validated with the results of other articles. In this article, the effect of fiber diameter on the radiative heat transfer coefficient is investigated. The results show that the radiant heat transfer coefficient of the fibers changes with the change of the diameter of the fibers and also the radiant heat transfer coefficient of silica insulation will be minimum if the fiber diameter is 6 micrometers, and with increasing or decreasing the fibers diameter, the radiant heat transfer coefficient will increase. In the case of silicon fiber insulation, the fiber diameter of 4 micrometers will have the lowest radiation heat transfer.

Introduction: Post and core has been considered for endodontically treated tooth, especially in cases with severe damage crowns. Recently fiber reinforced composite posts (FRC post) have been used in the treatment of endodontically treated teeth. Because the length and diameter of posts are effective in stress distribution, the purpose of this study is to evaluate the effect of length and diameter of FRC post on fracture resistance.Methods: In this experimental study, 36 glass fiber posts with combination of 7mm, 9mm, and 12mm length and 1.1mm, 1.3mm and 1.5mm diameter were divided into 9 groups of 4. These posts were cemented in root canals by Panavia. Samples were tested with 45o compressive forces for the evaluation of fracture resistance. Datas were analyzed using SPSS soft ware and One- way and Two-way ANOVA analyses.Results: Fracture resistance did not increase significantly with the effect of length and diameter simultaneously (P=0.85). Samples with 12mm length and 1.5mm diameter had the greatest fracture resistance (1023.33N±239.22). The minimum fracture resistance had occurred in post with 7mm length and 1.5mm diameter (503.13N±69.18). Fracture resistance increased significantly by increasing the length and the same diameter.Conclusion: It can be concluded that fracture resistance is affected by the length and not the diameter of FRC post.

Growing interest in wood and paper consumption in Iranian industries and forest utilization constraints call for alternative approaches on the exploitation trend. Lately, industrial countries consider utilization of small diameter trees and branches residual wood. European hornbeam with vast coverage among the other species in Iran can be an alternative to tree shortage of raw material for the sector. This study showed that the branch fiber dimensions have significantly differed compare to trunk.Average fiber length was measured as 1.76mm for breast height of three trunks and 1.43 mm for two branches samples. Fiber length increased from crown downward to the stump and also from pith to bark, but there was a significant negative correlation between the variations and tree height. Fiber length increased in trees of up to 30 years of age and decreased afterwards. There is no orderly pattern from tree base to the upper branches.Runkel and flexibility coefficients of branch were better than trunk despite of higher fiber dimensions in trunk.

Wood consumption is increasing in different regions of the world and population growth is also enforces this demand. Since the world natural forests are limited, therefore, different societies has concentrated their effort on fast growth plantation species especially various poplar species and clones. Iran has also concentrated on importing and cultivating different poplar species. Among them two clones (P.deltoids 77/51 and P.deltoides 69/55) showed both excellent adaptation and growth in Gilan. Therefore, wood producing farmers paid special attention on these clones. Even thought both adaptation and growth is favorable for plantation of these clones, but their wood technological characteristics must fulfill the industrial requirement. Since fiber geometry of any wood will influence its application for industrial commodities, therefore, in this study, the fiber geometry of these clones including fiber length, diameter, lumen diameter and cell wall thickness were measured. Fiber length, diameter and cell wall thickness of P.deltoids 77/51 were measured at 947, 25.35 and 5.24 micron respectively. The related values for P.deltoids 69/55 were at 971, 24.99 and 5.46 micron respectively

This research was performed to investigate fiber biometrical properties (length, diameter and fiber thickness) of hornbeam species from Astara in Iran. Initially, disks were prepared with three trees of hornbeam species and then fiber isolation was carried out using Franklin method. Length, diameter and wall thickness of fiber provided were determined by laboratory microscope using eye scaled lens. The measurement of fiber dimensions was made at the pith region and at the distances of 2, 6, 12 and 15 centimeters and four geographical sides. The results indicated that length, diameter and wall thickness of fiber increased significantly with enhance of distance from pith. The highest fiber length, diameter and wall thickness obtained were 1.509 mm, 23.93 μm and 3.897 μm, respectively. The consequences attained from changing of fiber dimensions at various distances from pith to bark indicated that fiber dimensions change decreased by increase in distance from pith up to 15 cm and the highest change of fiber was observed at distance of 2-6 cm from pith. The results of measuring the fiber dimensions at various geographical sides didn't indicate any significant deference between the values of fiber length, diameter and wall thickness at 1% level of probability. The combined effects of distance from pith and different geographical sides also did not show any significant deference on fiber dimensions.