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13 results on '"Larimian, Taban"'

12. Inactivation mechanisms of Escherichia coliO157:H7 and Salmonella entericaby free residual chlorineElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2ew00382a

Author

Abnavi, Mohammadreza Dehghan, Larimian, Taban, Srinivasan, Parthasarathy, Munther, Daniel, and Kothapalli, Chandrasekhar R.

Abstract

The sub-cellular mechanisms by which residual free chlorine (FC) inactivates E. coliO157:H7 and S. entericain the absence of organic matter was investigated. The average removal rates for E. coliwere 38–99% after a 1 min exposure to 0.12–0.5 mg L−1FC, while that of S. entericawere 10–50% after exposure to 0.5–2.0 mg L−1FC. Chlorination caused significant membrane structural damage and reduced membrane potential. Low FC levels or short exposure times had a modest impact on S. enterica. Cell metabolic activity decreased over time for all initial FC levels, and with increasing FC levels at each time point. Total ATP levels increased in the first minute post-chlorination, while the intracellular ATP levels decreased with increasing FC levels and exposure time, likely due to ATP leakage. The depolarized E. colidensity reached a plateau after the first 2 min at FC ≥ 0.5 mg L−1while that of S. entericatook 5 min to reach a plateau even at FC ≥ 1 mg L−1, indicating their ability to withstand chlorination. Residual FC levels are sufficient to induce damage to cellular organelles and compromise their survival, and the mechanism of injury depends on FC levels and exposure time.

Published
2022
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13. Mechanistic Understanding of Amorphization in Iron-Based Soft Magnetic Materials

Author

Larimian, Taban

Subjects
Engineering, Materials Science, Mechanical Engineering, Finemet, FeSiB, FeSiBNb, FeSiBCu, Spark Plasma Sintering, Mechanical alloying, Soft magnetic materials, Magnetization, Energy map
Abstract

Iron-based magnetic alloys possess very good magnetic and mechanical properties. Among these alloys Fe-Si-B-based alloys show outstanding saturation magnetization and coercivity which makes them great candidates for many industrial applications. Addition of certain elements to the Fe-Si-B base is proven to improve the homogeneity and fineness of microstructure as well as enhance the magnetic behavior of these alloys. In this research work, we have studied the effect of adding copper and niobium to the Fe-Si-B base alloy.Previous studies have shown that magnetic alloys show better magnetic properties when their microstructure consists of nanocrystals embedded in an amorphous matrix. In order to reach amorphization, magnetic alloys are traditionally melted and then cooled down very fast to prevent crystallization and grain growth in their microstructure. However, there are several disadvantages associated with this method of fabrication, such as the limitation in thickness of the products. To solve this issue, we proposed a new method of fabrication for magnetic alloys where amorphization occurs through mechanical alloying, and the amorphous powder alloy that is produced by this process is then consolidated using a technique called spark plasma sintering finding appropriate mechanical alloying processing parameters to get an amorphous structure. Many different processing parameters were investigated, and the mechanical properties, microstructure, and magnetic properties of all samples were examined. The effect of spark plasma sintering processing parameters on samples sintered from the amorphous powders was then studied.Finally, the amount of energy introduced to the powder from the milling balls during the mechanical alloying process was calculated. We were able to find a trend between the energy introduced to the powder during the milling process and the amorphous structure of the milled powders. From our data, we draw an energy map that shows the window of total energy in which the powder, regardless of the mechanical alloying processing parameters under which it was milled, will show an amorphous structure. This area has not been explored for these magnetic alloys before, and this data can be used by researchers who are trying to obtain amorphization via the mechanical alloying process.

Published
2022

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