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Showing 2 results for Seyyednejad
Volume 18, Issue 7 (Supplementary Issue - 2016)
Abstract
This study was conducted under Ahvaz, Iran environmental condition during 2012 and 2013 growing seasons in order to investigate the influence of foliar application of potassium on some physiological and biochemical characteristics of three olive cultivars including ‘Mission’, ‘Koroneiki’ and ‘Dezfuli’. Potassium sulfate in different concentrations of 0, 1, and 2 g l-1 was sprayed twice on selected mature 10 year old trees; at 50 and 65 days after full bloom. Potassium sprays increased leaf chlorophyll content of all cultivars, leaf potassium content in ‘Mission’ and ‘Koroneiki’ cvs., fruit anthocyanin concentration of ‘Dezfuli’ in two crop seasons. However, K treatments had no significant effect on leaf N and P content, fruit K and P content in all studied cultivars. Fruit soluble carbohydrates increased by foliar application of potassium in ‘Koroneiki’ and ‘Dezfuli’ cultivars in the second year of study. Stem water potential and leaf stomatal conductance were significantly affected by cultivar and K treatments during the two years. Our findings showed that foliar application of potassium resulted in the decrease of stomatal conductance of ‘Koroneiki’ and ‘Dezfuli’ in two crop seasons. Based on the results, it can be concluded that the studied cultivars differently respond to K treatments during the two crop seasons and foliar potassium application could have a positive impact on leaf chlorophyll, leaf potassium, fruit soluble carbohydrates and fruit anthocyanins in olive cultivars.
Volume 21, Issue 4 (April 2021)
Abstract
Delamination is one of the most common modes of damage in laminated composites that can reduce stiffness and load-bearing capacity of the composite structure, which highlights the importance of studying of this phenomenon. For this purpose, in this study, the effect of the interface fiber angles on the mode II fracture toughness of plain woven laminated composites has been investigated. The end notch flexure specimens (ENF) with 24 layers which have 0//0, 0//30 and 30//-30 interface angles manufactured using hand lay-up method and experimental tests conducted on them in accordance with ASTM standard under load II mode loading. Experimental results show that the interface fiber angle has a significant effect on initiation and propagation of delamination toughness the initial and propagation fracture toughness, so that the load bearing capacity of the specimens with the non-zero interface fiber angle was the highest value. Moreover, the initiation and propagation value of fracture toughness for specimens with 0//0 interface fiber angle was less than the corresponding values for other samples with non-zero interface angles. In addition, the fracture process zone (FPZ) length was approximately the same for all samples. Taken images of fracture surfaces using scanning electron microscopy (SEM) show that in addition to the separation of fibers from the resin at delamination, other damage mechanisms Including fiber breakage and highly deformed matrix play a key role in increasing of the fracture toughness of the sample with 0//30 and 30//-30 interface fiber angle.
