mohammad izadpanah

Thin-walled energy-absorbing elements in compressive loading are widely used in the transportation industry, especially in automobile manufacturing, airplane manufacturing, and urban and intercity train construction. As a new idea, coaxial double-tube energy absorbers are used in this research. The execution method is based on simulation in ABAQUS explicit finite elements software. Based on the validated model, a parametric analysis has been carried out in order to extract the effect of structure thickness, loading angle and density of polyurethane foam on the amount of energy absorption. Examining the deformed geometry of the sample after loading, the dynamic loading coefficient and the effect of the load angle on the maximum value of the structure collapse to the initial length is one of the topics that has been taken into consideration. In the end, according to the design goals, which include the maximum amount of energy absorption, the lowest amount of initial maximum force and the lowest weight of the structure, the optimization process of the design variables, using the optimization algorithm and formulation of multiple goals and with the help of finite element software data, has been completed.

The prevalence of bacterial drug resistance and consequently the reduction of antibiotic effects on bacteria encourages researchers to seek appropriate and low-risk alternatives for treatment of infectious diseases. Nanoparticles and herbal extracts can be considered as good alternatives to antibiotics. The aim of this study was to investigate the antimicrobial effect of silver nanoparticles in comparison to Seidlitzia rosmarinus extract on multidrug resistant (MDR) strains of Staphylococcus aureus (S. aureus) and Klebsiella pneumoniae (K. pneumoniae).
S. aureus and K. pneumoniae were isolated from urinary tract infections. Doses of 50, 100, 200, and 400 mg/mL of alcoholic extract of Seidlitzia rosmarinus and also 5, 10, 20, and 80 µg/mL of silver nanoparticles were added to Agar with S.aureus or K. pneumoniae. Then, Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were evaluated.
Seidlitzia rosmarinus extracts conferred a noticeable effect on S. aureus (MIC = 100 mg/mL and MBC = 100 mg/mL), while silver nanoparticles were a higher inhibitory effect on K. pneumoniae (MIC = 5 µg/mL and MBC = 10 µg/mL). Both the extract and nanoparticles inhibited dose dependently the growth of S. aureus and K. pneumoniae.
It seems that Seidlitzia rosmarinus extract and silver nanoparticles prevent the growth and proliferation of S.aureus and K. pneumoniae in a dose dependent manner.