Indian Institute of Technology Madras

About: Indian Institute of Technology Madras is a facility organization based out in Chennai, Tamil Nadu, India. It is known for research contribution in the topics: Heat transfer & Finite element method. The organization has 20118 authors who have published 36499 publications receiving 590447 citations.

Potential of silver nanoparticle-coated polyurethane foam as an antibacterial water filter

Abstract: Silver nanoparticles can be coated on common polyurethane (PU) foams by overnight exposure of the foams to nanoparticle solutions. Repeated washing and air-drying yields uniformly coated PU foam, which can be used as a drinking water filter where bacterial contami- nation of the surface water is a health risk. Nanoparticles are stable on the foam and are not washed away by water. Morphology of the foam was retained after coating. The nanoparticle binding is due to its interaction with the ni- trogen atom of the PU. Online tests were conducted with a prototypical water filter. At a flow rate of 0.5 L/min, in which contact time was of the order of a second, the output count of Escherichia coli was nil when the input water had a bacterial load of 10 5 colony-forming units (CFU) per mL. Combined with the low cost and effectiveness in its applications, the technology may have large implications to developing countries. B 2005 Wiley Periodicals, Inc.

Thermal conductivities of naked and monolayer protected metal nanoparticle based nanofluids: Manifestation of anomalous enhancement and chemical effects

Abstract: Thermal conductivities of two kinds of Au nanoparticles were measured in water and toluene media. The water soluble particles, 10–20 nm in mean diameter, made with citrate stabilization showed thermal conductivity enhancement of 5%–21% in the temperature range of 30–60 °C at a loading of 0.000 26 (by volume). The effect was 7%–14% for Au particles stabilized with a monolayer of octadecanethiol even for a loading of 0.011%. Comparatively lower thermal conductivity enhancement was observed for larger diameter Ag particles for significantly higher loading. Effective enhancement of 9%, even at vanishing concentrations, points to additional factors in the thermal conductivity mechanism in nanofluids. Results also point to important chemical factors such as the need for direct contact of the metal surface with the solvent medium to improve enhancement.

A classification of studies on properties of foam concrete

Abstract: Though foam concrete was initially envisaged as a void filling and insulation material, there have been renewed interest in its structural characteristics in view of its lighter weight, savings in material and potential for large scale utilization of wastes like fly ash. The focus of this paper is to classify literature on foam concrete in terms of constituent materials (foaming agent, cement and other fillers used), mix proportioning, production methods, fresh and hardened properties of foam concrete. Based on the review, the following research needs have been identified: (i) developing affordable foaming agent and foam generator, (ii) investigation on compatibility between foaming agent and chemical admixtures, use of lightweight coarse aggregate and reinforcement including fibers, (iii) durability studies, and (iv) factors influencing foam concrete production viz., mixing, transporting and pumping.

Coalescence of Nanoclusters and Formation of Submicron Crystallites Assisted by Lactobacillus Strains

Abstract: Lactobacillus strains, common in buttermilk, assist the growth of gold, silver, and gold-silver alloy crystals of submicron dimensions upon exposure to the precursor ions. Several well-defined crystal morphologies are observed. Crystal growth occurs by the coalescence of clusters, and tens of crystals are found within the bacterial contour. Crystal growth does not affect the viability of the bacteria. Crystals are presumably nucleated through nanoclusters, which are formed within as well as transported into the bacteria. Biomass with the crystals can be harvested completely. Results point to potential applications in analytical chemistry, nanotechnology, medicine, and metal ion recovery. Coalescence appears to be a route by which surface area of the crystal is reduced so that it can be effectively protected to avoid biological damage.