COMPOSITES PART B-ENGINEERING

The mechanical, thermal, chemical, crystallographic and morphological properties of althaea fibres, extracted from Althaea officinalis L, was examined for the first time in this study. A. officinalis L. was obtained from Mordogan, Izmir (Turkey). After extraction process, lignin, cellulose and hemicellulose contents of althaea fibres were identified. Fourier transform infrared and X-ray photoelectron spectroscopy were utilized for surface functional groups of althaea fibres. By using X-ray diffraction analysis, CI value for althaea fibre is obtained to be 68%. The images of scanning electron microscopy were taken for observation of morphology of althaea fibres. The tensile modulus and tensile strength values of althaea fibre were obtained by single fibre tensile tests as 415.2 MPa and 65.4 GPa, respectively. Thermogravimetric analysis showed that thermal degradation of the fibre begins at approximately 220 degrees C. Besides, by pulling out the althea fibre from the embedded high density polyethylene, interfacial shear strength value was determined to be 8.16 MPa. The results suggest that the althaea fibre can be used in composite applications as a natural reinforcement material. (C) 2013 Elsevier Ltd. All rights reserved

The influence of oligomeric siloxane concentration on the mechanical behaviors of alkalized jute/modified epoxy composites

In this study, jute fabrics/modified epoxy composites were fabricated by means of hand lay-up process. In order to enhance adhesion between the alkalized jute fabric and epoxy, modification processes was carried out by applying an oligomeric siloxane at different concentrations into epoxy matrix. The influence of resin modification processes on mechanical properties was examined. Tensile and flexural properties and interlaminar shear strength (ILSS) of the composites were measured. It was shown that the ILSS values are increased from 14.18 MPa for alkalized jute fabric/epoxy composite to 22.82 MPa for alkalized jute fabric/3% (w/w) oligomeric siloxane modified epoxy composite. The improved adhesion between the fiber and the matrix may be a result of modification of epoxy matrix with an oligomeric siloxane. This conclusion was confirmed by the morphology observations investigated by scanning electron microscopy. Besides, the modification of epoxy with 3% (w/w) oligomeric siloxane resulted in 30.4% increase in the tensile strength of alkalized jute fabric/epoxy composite. From results of the flexural modulus, application of oligomeric siloxane into epoxy matrix leads to much stiffer jute fiber-epoxy composite. © SAGE Publications 2010

Developing an in-vitro mechanical stretching system for moleculer cell biology studies (in English)

14th National Biomedical Engineering Meeting -- MAY 20-22, 2009 -- Izmir, TURKEYWOS: 000274345400052The human mesenchymal stem cells can differentiate into cardiomyocytes, osteoblasts, chondroblasts, adipocytes, endothelial, hepatocyte and neuron cells, when hMSCs are exposed to certain physical and chemical stimulants. It is hoped that the differentiation of hMSCs into certain cell types in certain in-vitro conditions can provide for treatment of the certain disease and pathologic situation. The suitable cell culture conditions, which are needed for differentiation of hM5Cs into osteoblast, chondroblasts and adipocyte cells, are known. However, these cells do not reach to terminal differentiation but they can differentiate only into osteoblast, chondroblast and adipocyte-like cells. It is thought that these cells are precursor cells. Moreover, hMSCs can differentiate into different types of cells under the mechanical stress (mechanical stretching, pressure, shear stress) as the physical stimulus. However, it is not clear whether mechanical stretching provides for the hM3Cs to reach terminal differentiation or not. It was found that the tension on the cytoskeleton and/or the tension in the junctions between the cells caused hMSCs to choose the certain cells type differentiation way. Increasing acknowledge about parameters of the tension in the cells and/or between the cells can provide that these parameters can be used to follow the progression of pathologic situation and the diagnosis of some cardiac, bone, joint and muscle tissue diseases. Nowadays, there are several projects about finding mechanical properties of the soft and hard tissues in the biomedical fields To show properly working of in-vitro mechanical, 6 hours, 5% and 1 Hz of mechanical stress was applied for hMSCs. factin florescence stainin was done to see stress fibers. Stress fibers were observed after mechanical stress. In the present study, in-vitro mechanical stretching system (iMecS) was developed with experimental applications

Effect of final irrigation procedures on fracture resistance of root filled teeth: an ex vivo study

PubMed ID: 27464713Aim: To evaluate the effect of chlorhexidine (CHX) on fracture resistance of roots treated with different concentrations of ethylenediaminetetraacetic acid (EDTA). Methodology: One hundred and twenty intact single-rooted premolar teeth were sectioned below the cementum–enamel junction to standardize the length of the teeth to 12 mm. The canals of one hundred specimens were instrumented with ProTaper Universal rotary instruments up to size F4 and were randomly divided into five groups (n = 20) according to the final irrigating solutions: Group 1: distilled water (DW); Group 2: 5% EDTA and 2.5% NaOCl; Group 3: 17% EDTA and 2.5% NaOCl; Group 4: 5% EDTA, 2.5% NaOCl, DW and 2% CHX; Group 5: 17% EDTA and 2.5% NaOCl, DW and 2% CHX. Root canals were filled with gutta-percha and epoxy resin-based root canal sealer using a single-cone technique. Twenty teeth served as negative controls and were not instrumented nor root filled (Group 6). All specimens were embedded in self-curing acrylic resin and loaded vertically at 0.5 mm min-1 until fracture occurred. The data were evaluated statistically using one-way anova test followed by Holm–Sidak's multiple comparison test (P < 0.05). Results: Group 1 (only DW) had the lowest vertical fracture strength, followed by Group 3 (17% EDTA and 2.5% NaOCl; P < 0.05). Group 6 (negative control group) had the highest fracture resistance. Final irrigation with CHX following irrigation with 17% EDTA or 5% EDTA and 2.5% NaOCl (groups 4 and 5) significantly increased the fracture resistance of roots (P < 0.05). However, the difference between Group 4 and Group 5 was not significant (P > 0.05). Conclusions: Intracanal CHX rinse of EDTA/NaOCl-treated root dentine enhanced the fracture resistance of roots filled with AH Plus. © 2016 International Endodontic Journal. Published by John Wiley & Sons Lt

Effect of siloxane treatment of jute fabric on the mechanical and thermal properties of jute/HDPE

The mechanical and thermal properties of jute fiber/HDPE composites as a function of alkali and oligomeric siloxane treatment of jute fabric were investigated. The effect of surface treatments on the composites was assessed by means of tensile test, short-beam shear test, three-point bending test, SEM, TGA, and DSC. When jute fabric are first treated with alkali solution and then oligomeric siloxane solution, 34% and 49% increases in tensile and flexural strength were observed, respectively. Moreover, it is interesting to note that after alkali and siloxane treatment of jute fabric, 169% increase in ILSS of jute/HDPE composite was obtained. This demonstrates that the adhesion between jute fiber and HDPE matrix is greatly increased by alkali and oligomeric siloxane treatment of jute fabric. This observation was also confirmed by SEM analysis of fracture surface of composites. Alkali and oligomeric siloxane treatment of jute fabric did not considerably change thermal stability and melting and crystallization temperatures of jute/HDPE. © 2012 The Author(s)