Self-healing capability of large-scale engineered cementitious composites beams

YesEngineered Cementitious Composites (ECC) is a material which possesses advanced self-healing properties. Although the self-healing performance of ECC has been revealed in numerous studies, only small-scale, laboratory-size specimens have been used to assess it under fixed laboratory conditions and curing techniques. In order to evaluate the effect of intrinsic self-healing ability of ECC on the properties of structural-size, large-scale reinforced-beam members, specimens with four different shear span to effective depth (a/d) ratios, ranging from 1 to 4, were prepared to evaluate the effects of shear and flexural deformation. To ensure a realistic assessment, beams were cured using wet burlap, similar to on-site curing. Each beam was tested for mechanical properties including load-carrying capacity, deflection capacity, ductility ratio, yield stiffness, energy absorption capacity, and the influence of self-healing, by comparing types of failure and cracking. Self-healed test beams showed higher strength, energy absorption capacity and ductility ratio than damaged test beams. In test beams with an a/d ratio of 4 in which flexural behavior was prominent, self-healing application was highly successful; the strength, energy absorption capacity and ductility ratios of these beams achieved the level of undamaged beams. In addition, flexural cracks healed better, helping recover the properties of beams with predominantly flexural cracks rather than shear cracks.The authors gratefully acknowledge the financial assistance of the Scientific and Technical Research Council (TUBITAK) of Turkey provided under Project: MAG-112M876 and the Turkish Academy of Sciences, Young Scientist Award program. The second author would also like to acknowledge the financial support of TÜBITAK for the 2219 Scholarship

Effect of Fly Ash Fineness on the Activation of Geopolymer Concrete

In the field of construction materials and particularly in concrete, cement is considered as a key element since it generates a strong and durable material through a simple hydration process. However, for many reasons (mainly economic and environmental) researchers are trying to find a new material that could replace cement or at least part of it as a binding agent in concrete. Regarding this issue, cement replacement materials like fly ash and slag have taken the lead during the last few decades. These materials have characteristics similar to cement but when it comes to the hydration they first need to be activated. For that, many studies were performed to find a way to activate these materials without using cement to produce what is called Geopolymer Concrete. The activation is simply based on preparing an ambient similar to the one produced by cement hydration. Hence, alkali activation is widely used to activate the polymerization reaction. On the other hand, when compared to ordinary concrete, producing geopolymer concrete is still complicated since it has no standard and needs several activation steps. In this work, fly ashes that are taken from three different sources in Turkey are used to produce geopolymer concrete. The study aims to compare the effect of fly ash characteristics, particularly their chemical composition and fineness, on the activation process

The Impact of Resveratrol on Oxidative Stress Induced by Methotrexate in Rat Ileum Tissue: Evaluation of Biochemical and Histopathological Features and Analysis of Gene Expression

Cetin, Nihal/0000-0003-3233-8009; Malkoc, Ismail/0000-0002-9221-510XWOS: 000370081000014PubMed: 26517535Objective: the aim of this study was to assess the impact of resveratrol (RST) on oxidative stress induced by methotrexate in rat ileum tissue. Materials and Methods: Twenty-four rats were divided into 4 groups with 6 in each group. Each rat was orally administered the following every day for 30 days: group 1 (MTXG), methotrexate (MTX; 5 mg/kg); group 2 (RMTXG), MTX (5 mg/kg) plus RST (25 mg/kg/day); group 3 (RSTG), RST alone (25 mg/kg/day), and group 4 (controls), distilled water. After the rats had been sacrified, the ilea were removed for the assessment of malondialdehyde (MDA), total glutathione (tGSH) and glutathione peroxidase (GSH-Px). Gene expression analyses for interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha) and myeloperoxidase (MPO) were also performed. Hematoxylin and eosin-stained paraffinembedded sections of the ileum were analyzed under a light microscope and the findings were recorded. Statistical analyses of the data were performed using one-way ANOVA. Results: the administration of MTX in group 1 yielded a higher level of MDA (8.33 +/- 2.5 mu mol/g protein, p < 0.001) and lower levels of tGSH (0.97 +/- 0.29 nmol/g protein) and GSH-Px (5.22 +/- 0.35 U/g protein, p < 0.001) compared to the other groups. MTX also increased IL-1 beta (40.33 +/- 5.43 gene expression levels), TNF-alpha (6.08 +/- 0.59) and MPO gene expression (9 +/- 1.41) in group 1 compared to the controls (11.33 +/- 2.07, 2.15 +/- 0.33 and 3.43 +/- 0.48, respectively, p < 0.001). the impact of RST on IL-1 beta, TNF-alpha and MPO gene expression induced by MTX was observed as a reversal of these findings (p < 0.05). Severe inflammation, damage to the villus epithelium and crypt necrosis was observed histopathologically in the MTXG group, whereas only mild inflammation was seen in the RMTXG group. Conclusion: in this study, ileal damage caused by MTX was inhibited by RST. (C) 2015 S. Karger AG, Base

Effect of Hippophae rhamnoides Extract on Oxidative Oropharyngeal Mucosal Damage Induced in Rats Using Methotrexate

Malkoc, Ismail/0000-0002-9221-510XWOS: 000402589900010PubMed: 27507269Objectives. the objective of this study is to investigate and evaluate the effect of Hippophae rhamnoides extract (HRE) on oropharyngeal mucositis induced in rats with methotrexate (MTX) through biochemical, gene expression, and histopathological examinations. Methods. Experimental animals were divided into a healthy group (HG), a HRE+MTX (HREM) group, HRE group (HREG), and a control group that received MTX (MTXG). the HREM and HREG groups of rats was administered 50 mg/kg HRE, while the MTXG and HG groups were given an equal volume distilled water with gavage. Then, the HREM and MTXG rat groups were given oral MTX at a dose of 5 mg/kg 1 hour after HRE and distilled water was administered. This procedure was repeated for 1 month. At the end of this period, all of the animals were sacrificed with a high dose of anesthesia. Then, the amounts of malondialdehyde (MDA) and total glutathione (tGSH) were determined in the removed oropharyngeal tissues. Interleukin-1 beta (IL-1 beta) and tumor necrosis factor-a (TNF-alpha) gene expressions were measured, and all the tissues were studied histopathologically. Results. the amount of MDA was significantly increased in the MTXG group compared to the HREM, HREG, and HG groups (P<0.001). MTX significantly decreased the amount of tGSH in the MTXG group compared to the HREM, HREG, and HG groups (P < 0.001). in this study, there were no visible ulcers in the animal group in which the levels of MDA, IL-1 eta, and TNF-alpha were high and the level of tGSH was low. However, histopathologic examination revealed mucin pools in wide areas due to ruptured oropharynx glands, and proliferated, dilated, and congested blood vessels and dilated ductal structures in some areas. Conclusion. HRE protected oropharyngeal oxidative damage induced by MTX. As an inexpensive and natural product, HRE has important advantages in the prevention of oropharyngeal damage induced by MTX