Volume 11, Issue 3 (10-2022)
Abstract
The geometric-morphometric method has become a vital tool for examining shape and size variations. The current study analyzed the effect of gamma radiation on wing characteristics of sterile and normal Medflies, C. capitata, on landmark-and outline-based geometric morphometrics. In landmark-based, there were significant differences in weight matrices as shape variable, but the centroid size as size variable was statistically non-significant between the two populations. PCA of the sterile and normal populations manifested a clear distinction from the results. MANOVA further ascertained significant wing shape differences between sterile and normal populations. In the outline-based approach, PCA of the contours revealed that 10 out of the 80 principal components effectively explained shape attributes. The statistical tests were utilized to introduce the significant influence considered in the sterile insect technique (SIT) because, in the long run, these changes may distort the results of SIT project.
Volume 19, Issue 2 (February 2019)
Abstract
Incidence of breaks and leakages in fluid transportation pipes is a common issue in Iran. Depending on the type of pipes and environmental conditions, the breaks in the pipes may be caused by different factors, including mechanical damages, internal or external corrosions, failures, or applied stresses. In the repair of damaged pipes, there are several strategies for rebuilding and implementing the pipeline, most of which are replacing the entire exhausted pipe, using weld clamps and using composite patches. In recent years, the use of composite patches has been accepted as a low-cost, permanent, and standard method for different pipe sections with the least interruption in transportation. In the present study, the boding strength of glass fibers-reinforced epoxy composite patches on a structural steel substrate were investigated and optimal conditions of achieving enhanced adhesion strength of composite patches on the steel substrate were determined, using the Tagochi method at various curing temperatures and times. In this regard, the tensile and shear strength of epoxy, cyanoacrylate, and methacrylate-based glues as three kinds of appropriate polymers for bonding the epoxy composite on the steel substrates were tested. The mechanical strength measurements and fractured interfaces evaluations using a scanning electron microscopy (SEM) revealed that the methacrylate-based glue has the better adhesion strength to the steel substrate.
Volume 23, Issue 4 (7-2021)
Abstract
The European corn borer Ostrinia nubilalis (Hübner), as a worldwide corn pest, causes serious damages. In the present study, some biological aspects of O. nubilalis were investigated on three different host plants including corn stalks, potato, and soybean stems, and a specific semi-artificial diet. Once appropriate host was selected, developmental rates of eggs, larval and pupal stages as well as moth emergence, longevity, and female fecundity were determined at four constant temperatures (20, 24, 28, and 32±1°C). The relationship between temperature and developmental rate was estimated with two linear models under laboratory condition (70-80% RH and a photoperiod of 16L:8D hour). Results showed significant differences between studied foods, such that corn stalk sections and semi-artificial diet were appropriate host for O. nubilalis compared to the other two hosts. It was also revealed that optimum temperature for growth of this pest was 28°C. Lower developmental threshold estimated by traditional and Ikemoto-Takai linear models for whole immature stages were about 9 and 10°C, and thermal constants were 473 and 431 degree day (DD), respectively. Compared to previous studies, these values were similar in the immature stages, except for the larval stage, which could indicate the importance of nutrition and role of the plant host in temperature requirements.
