Showing 4 results for Tutunchi
Sina Ariaee, Abolfazl Tutunchi, Abbas Kianvash,
Volume 14, Issue 9 (12-2014)
Abstract
In the present study, central composite algorithm was used in order to model and optimize the mechanical behavior of “glass fiber reinforced epoxy composite - structural steel “connections. Initial tests showed that the polymer curing variables play a significant role as key process parameters in producing strong and reliable connections. After conducting Thermal Gravimeteric Analysis on polymer, by selecting curing time and curing temperature as input variables, the parameters were coded and each of them was studied in five levels. In order to estimate the desirable response and provide appropriate models, thirteen tests were conducted systematically. In order to assess the accuracy and to validate the proposed model, analysis of variance was performed successfully. The effect of curing time and curing temperature on the connection’s strength quality was studied utilizing two-dimensional graphs. Utilizing this approach the optimal bonding process variables was achieved at 40°C and 180 min for curing temperature and curing time respectively. Finally, the results obtained from micro structural characterization and fractography analyses of joints by Optical and Scanning Electron Microscope were in good agreement with the results achieved by the developed model.
Volume 16, Issue 95 (January 2019)
Abstract
Red beet has nutritional and health benefits due to presence of bioactive components such as phenolic and betalain compounds. Thus, the improving of extraction efficiency and stability of red beet compounds has gained the attention of researchers. In this study, β-CD-enhanced ultrasound assisted extraction was used for extraction of red beet extract and the lyophilized extracts were characterized with FTIR and UV–Vis spectrophotometry analyses. The extracted samples with aqueous 5 % β-CD solutions revealed highest content of betanin (2.24 ± 0.04 mg /g DW) and total phenolic compounds (20.03 ± 1.28 mg GAE/g DW) and as well highest DPPH inhibition activity (59.87 ± 4.94 %). In conclusion, the β-CD-enhanced ultrasound assisted extraction is a suitable technique to extraction and stabilize the red beet compounds for applications in functional food, nutraceutical, and medical fields.
Volume 19, Issue 1 (5-2016)
Abstract
Objective: Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen with numerous virulence factors considered to be one of the most etiological agents in nosocomial infections. The emergence of multi-drug resistant (MDR) P. aeruginosa has become a serious, worldwide public health threat. This study intended to determine the frequency of phzM, phzS, phzH, phzI, and phzII genes in MDR P. aeruginosa strains isolated from clinical samples.
Methods: In this cross-sectional study, we examined 93 isolates of P. aeruginosa collected from different clinical samples in Zanjan during 1393-94. After identification of isolates by biochemical tests, we performed the antibiotic susceptibility test (Kirby-Bauer) per CLSI guidelines. Then, total DNA was extracted for PCR analysis to detect phzM, phzS, phzH, phzI, and phzII genes.
Results: P. aeruginosa isolates exhibited high-level resistance to Erythromycin and Cefoxitin (95.6%). Amikacin showed the highest activity against isolates with 73.2% susceptibility. There were 88 (94.6%) MDR isolates. The genes had the following frequency among MDR isolates: phzI (96.5%), phzII (93.1%), phzM (45.4%), phzS (27.2%), and phzH (27.2%).
Conclusion: The pathogenesis of P. aeruginosa is clearly multifactorial as shown by the large numbers of virulence factors and the broad spectrum of diseases this bacterium causes. The results indicated a greater frequency of phzI and phzII genes in MDR P. aeruginosa strains. This finding could be an alarm for the infections caused by this microorganism.
K. Osouli-Bostanabad, A. Tutunchi , M. Eskandarzade , A. Kianvash ,
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.
