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Your search keyword '"Tirumkudulu, Mahesh S."' showing total 180 results
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180 results on '"Tirumkudulu, Mahesh S."'

7. A theory for the compression of two dimensional strongly aggregated colloidal networks

Author

Roy, Saikat and Tirumkudulu, Mahesh S

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

The consolidation of suspended particulate matter under external forces such as pressure or gravity is of widespread interest. In this work, we derive a constitutive relation to describe the deformation of a {\it two-dimensional} strongly aggregated colloidal system by incorporating the inter-particle colloidal forces and contact dynamics. The theory accounts for the plastic events that occur in the form of rolling/sliding during the deformation along with elastic deformation. The theory predicts a yield stress that is a function of area fraction of the colloidal packing, the coordination number, the inter-particle potential, coefficient of friction and the normal and tangential stiffness coefficients. The predicted yield stress scales linearly with area fraction for low area fractions, and diverges at random close packing. Increasing the normal stiffness coefficient or the friction coefficient increases the yield stress. For stresses greater than the yield stress, both elastic and plastic deformations contribute to the overall stress., Comment: 23 pages, 5 figures

Published
2014

9. Asymptotic analysis of stresses near a crack tip in a two dimensional colloidal packing saturated with liquid

Author

Sarkar, Arijit and Tirumkudulu, Mahesh S

Subjects
Condensed Matter - Soft Condensed Matter, Condensed Matter - Materials Science
Abstract

The consolidation of colloidal particles in drying colloidal dispersions is influenced by various factors such as particle size and shape, and inter-particle potential. The capillary pressure induced by the menisci, formed between the top layer of particles in the packed bed, compresses the bed of particles while the constraints enforced by the boundaries result in tensile stresses in the packing. Presence of flaws or defects in the bed determines its ultimate strength under such circumstances. In this study, we determine the asymptotic stress distribution around a flaw in a two dimensional colloidal packing saturated with liquid and compare the results with those obtained from the full numerical solution of the problem. Using the Griffith's criterion for equilibrium cracks, we relate the critical capillary pressure at equilibrium to the crack size and the mechanical properties of the packed bed. The analysis also gives the maximum allowable flaw size for obtaining a crack free packing., Comment: 10 pages, 10 figures, Under review in Physical Review E

Published
2010
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28. Development of antibacterial waterborne polymeric coating using iodine complex

Author

Sekar, Hariharan, Tirumkudulu, Mahesh S., and Gundabala, Venkat

Abstract

With advancements in architectural coatings, the demand for antimicrobial coatings in this sector has increased significantly. The COVID-19 pandemic has also been a primary force behind the increased demand for and production of antimicrobial coatings. Typically, antimicrobial coatings are used to resist and decolonize microbial attacks such as biofilm formation, fungal contamination, and black mold formation. In this study, we synthesized a water-based antimicrobial polymer nanocomposite, I-P(MMA/BA), by blending an iodine complex with a poly (methyl methacrylate-butyl acrylate) latex with the aid of polyol and polyvinylpyrrolidone. Antimicrobial efficacy was evaluated in two habitats, namely planktonic and biofilm. Biomass studies indicated that iodinated latex nanocomposites and films show excellent antibacterial and antibiofilm activities. About 85–97% of biofilm formation was reduced by covering 15–30% of the area with iodinated latex film. The contact angle measurement of the iodinated latex-coated surface provides evidence of good hydrophobicity, which prevents stagnation of water over the surface. The developed dual-functional water-based iodinated nanocomposite displays great potential for inhibiting biofilm formation on surfaces when employed as a binder in paints.

Published
2023
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50. Trajectory of a model bacterium.

Author

Thawani, Akanksha and Tirumkudulu, Mahesh S.

Subjects
SIMULATION methods & models, ESCHERICHIA coli
Abstract

It is well known that bacteria, such as Escherichia coli, propel themselves in aqueous media by rotating helically shaped flagella. While a number of theoretical approaches have been proposed to model the detailed swimming motion, a rigorous comparison with experimental data is lacking due to the difficulty in simultaneously visualizing the motion of the head and the flagella along with the resulting trajectory. To this end, we have built a macroscopic working model of a bacterium and visualized its detailed motion in high-viscosity liquid. We show that a small asymmetry in the mass distribution in the head can lead to helical trajectories with large pitch and radius, which are reminiscent of the wiggling trajectories observed for swimming bacteria. The detailed motion agrees well with the predictions from slender-body theory that accounts for the asymmetric mass distribution in the head. Our study shows that the trajectory consists of two helical trajectories of different length scales - a large one caused by the asymmetric mass distribution and set by the head rotation rate, and a smaller one caused by the rotating flagellum and set by its rotation rate. We discuss implications of these results on the wiggling trajectories of swimming bacteria. [ABSTRACT FROM AUTHOR]

Published
2018
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