There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Adsorption of heavy metals on conventional and nanostructured materials for wastewater treatment purposes: A review

Role of nanomaterials in water treatment applications: a review.

This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are (small) systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. [J. Appl. Phys. 81, 6692 (1997)], was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.

A Benchmark Study on the Thermal Conductivity of Nanofluids

Most of the metal ions are carcinogens and lead to serious health concerns by producing free radicals. Hence, fast and accurate detection of metal ions has become a critical issue. Among various metal ions arsenic, cadmium, lead, mercury and chromium are considered to be highly toxic. To detect these metal ions, electrochemical biosensors with interfaces such as microorganisms, enzymes, microspheres, nanomaterials like gold, silver nanoparticles, CNTs, and metal oxides have been developed. Among these, nanomaterials are considered to be most promising, owing to their strong adsorption, fast electron transfer kinetics, and biocompatibility, which are very apt for biosensing applications. The coupling of electrochemical techniques with nanomaterials has enhanced the sensitivity, limit of detection, and robustness of the sensors. In this review, toxicity mechanisms of various metal ions and their relationship towards the induction of oxidative stress have been summarized. Also, electrochemical biosensors employed in the detection of metal ions with various interfaces have been highlighted.

A review on detection of heavy metal ions in water – An electrochemical approach

Micro fabricated cantilever beam smart immunosensor was modeled using "Intellisuite" software to detect nanogram level antigen. The FEM simulations were carried out with immunoglobulin antibody, IgG for the detection of C-reactive protein. The effect of geometry of the cantilever beam with different number of holes and thickness of Si piezo resistive-patch on the sensor performance and signal transduction was studied. The effect of nature of Si and CNT piezo resistive-patch on the sensor performance was also investigated. Considering the response of stress and sensitivity, CNT piezo resistive patch is more suitable for the development of smart sensor. A cantilever beam immunosensor 100 μm long, 50 μm wide and 2.4 μm thick with one hole 3 μm long and 6 μm wide in the beam and CNT piezo-patch 100 nm thick is a more promising system for the fabrication for the detection of C-reactive protein. The modeled sensor can detect CRP even at a low concentration of 11.0 ng/ml.

V. Velmurugan

Papers

Modeling of Micro-Electro Mechanical Systems Based Cantilever Beam as Biosensor for C-Reactive Protein