Volume 8, Issue 4 (fall 2022)
Abstract
Backgrounds: This study was done to evaluate the distribution of virulence-associated genes and antibiotic resistance in avian colibacillosis-causing Escherichia coli (E. coli) isolates.
Materials & Methods: In this study, 122 E. coli strains isolated from colibacillosis-suspected chickens in commercial broiler poultry farms (Guilan province, Iran) were examined for the presence of 12 virulence genes (hlyF, iroN, iss, iutA, ompT, astA, tra, sfa-foc, papC, fimH, cvi/cva, and Tia) using polymerase chain reaction (PCR). Antimicrobial susceptibility assessment was performed for the isolates using disc diffusion method against 19 antibiotics.
Findings: The fimH, iut, tra, iss, iroN, hly, and ompT genes were detected as the most prevalent genes among colibacillosis-causing isolates (more than 70%), while sfa-foc (S fimbriae and F1C fimbriae subunits) had the lowest frequency among colibacillosis-causing E. coli isolates (3.28%).
Conclusion: Virulence-associated genes were frequently detected in avian pathogenic E. coli strains. These findings could help better understand the pathogenicity potential of E. coli in poultry. Preventative measures are necessary to reduce food and environmental contamination with avian E. coli strains.
Volume 14, Issue 14 (Second Special Issue 2015)
Abstract
Curved thin-walled structures are extensively used in many industrial applications including aviation industries. These parts have a specific role in manufacturing of helicopter main rotor blade. Fracture mechanics parameters are needed for life estimation and life extension of curved thin-walled structures. Standard methods of fracture mechanics testing are not applicable to these parts because of curvature and thinness of the specimens. So new test methods for these specimens is necessary to be investigated and developed. Vast trying has been done by scientists to overcome these problems and some theories and experimental methods such as the theory of fracture of thin-walled curved plates, the conventional burst test method and some new non-standard test methods has been initiated and developed. In the present paper, first of all, the theory of thin-walled curved plates has been briefly presented to link the behavior of curved specimens to the flat ones and the conventional burst test (BT) method has been accordingly introduced. Then, the newly developed non-standard test methods such as compact curved tension (CCT), pin loading tension (PLT), three points bending (TPB), double edge notched tension (DENT), internal conical mandrel (ICM) and X-specimen have been reviewed. Finally, a comparison between mentioned methods had been done to determine the most appropriate one.
Volume 18, Issue 117 (November 2021)
Abstract
Ultraviolet radiation was used in the present study to process lemon juice. The designed UV system had five UV-C lamps and irradiation was performed based on the distance of the lamps (10, 20, and 30 cm) from the fluid layer and the circulation time (10, 20, and 30 minutes) of lemon juice in the system. Non-irradiated sample was also considered as a control treatment. The control and irradiated samples were filled in dark polyethylene bottles and stored at ambient temperature for 90 days. Immediately after irradiation and during the storage period, parameters such as pH, titratable acidity, total soluble solids, ascorbic acid content, color indices (L*, a*, and b*), browning index, as well as sensory attributes were evaluated. The pH, acidity, and total soluble solids did not show a definite trend. The results showed that among the color indices, L* decreased significantly, but a* and b* increased significantly during the storage period. The rate of color changes in irradiated samples from a distance of 10 cm was higher than other treatments. Irradiation also significantly reduced the ascorbic acid content of irradiated samples from a distance of 10 cm compared to other samples and control. However, the browning of irradiated samples from 10 cm distance was significantly less than that of irradiated samples from 20 and 30 cm distance. The score of the panelists indicated that irradiation and storage time altered the quality characteristics of lemon juice. The panelistschr('39') scores showed more acceptance of irradiated samples from 20 and 30 cm distance compared to irradiated samples from 10 cm distance. In general, the designed system in this study is not recommended for lemon juice processing due to the destructive effect of UV-C radiation on the content of ascorbic acid.
