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Due to the importance of consuming meat and meat products especially sausage and bologna and the adverse effects of using synthetic preservatives used in them, this study aimed to investigate the effect of natural preservative on shelf-life of cooked beefbologna and comparison with sodium nitrite as synthetic preservative. the effect of chitosan (0, 0.5 and 1%) added individually or in combination with CCEO nanoemulsion (0, 1, 2 and 3%) as an alternative for sodium nitrite on microbiological (Total Viable Counts, Coliforms, Lactic acid bacteria (LAB), molds and yeasts), pH and water holding capacity (WHC), of beef bologna stored at 4 °C for 30 days was investigated. The experiment was performed in completely randomized based on factorial in 3 replication. Duncans test at 5% probability level was used to determine the significant difference mean between the data. Results indicated that chitosan addition resulted in significant (p< 0.05) inhibition of microbial growth, so that the lowest microbial counts were obtained in the samples containing both chitosan and CCEO nanoemulsion indicating a possible synergistic effect. Chitosan also improved the WHC and reduced the synersis of the samples during shelf-life respect to the control, while CCEO nanoemulsion had no significant effect on these parameters (p>0.05). The combination of chitosan (1%) with CCEO nanoemulsion (2-3%), which showed the best results, could have a valuable potential for commercial use in order to improve preservation of meat products without the use of nitrites or other synthetic additives.

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In the present study, the effect of graphite nano platelet (GNP) as a filler on the vibrational properties of the epoxy EP411 DSM matrix was studied. For this purpose, GNP-epoxy composites samples were fabricated with 0-5 wt.% of GNPs using the solution mixing method. Free and forced vibrations tests on the cantilever composite specimens were conducted. Based on the free vibration results, the structural damping loss factor η was obtained as a function of the GNP loading. It was found that η   decreases as the GNP wt.% increases and reaches to the lowest value at 0-3 wt.% of GNP content, and  increases as the GNP loading increases and reaches to the value at 3-5 wt.% of GNP. Also, the frequency response function (FRF) around the second vibration mode was obtained for the neat epoxy. The Rayleigh damping coefficients were calculated employing the free and forced vibration results. The results revealed a nonlinear dependence of damping ratio η on the natural frequency of the neat epoxy. A representative volume element (RVE) incorporating 0-5 wt.% of GNPs was generated and the vibrational properties were numerically simulated. The modeling results were compared with those obtained from the experiment to verify whether the basic assumptions had been chosen properly.