The detection and counting of micro particles having sizes comparable to biological entities can provide a tremendous impetus to rapid diagnostics and clinical applications. MEMS technology has already been used in capture and detection of such micron size entities in miniscule concentrations. For this purpose a concentration step is normally added prior to the detection process. A variety of methodologies are used for quantization of such micron size particles/entities including change in permittivity, medium impedance, magnetic permeability and other means. Although optical studies have been extensively performed prior to this, it has not been used for quantization of the micro particles. We have designed, developed and characterized a MEMS counter which captures micron size fluorescent beads using delectrophoresis (DEP) and monitors their accumulation in a 12 μm x 230 μm size channel and monitors this accumulation as growth of overall fluorescence. The field is generated by a set of finely placed interdigitated microelectrodes. As we apply an alternating voltage at 10 V(pp) for a range of different frequencies we are able to capture the flowing beads and concentrate them by several orders of magnitude. This is also followed by their quantification in terms of growing fluorescence signal. For quantitating the fluorescence values a CCD (charge couple device) module fitted over an inverted fluorescence microscope is used that visualizes the whole capture process and a Labview based image acquisition software simultaneously calculates the signal intensity over these frames and arranges it temporally. Our work will have tremendous utility in developing a rapid bacterial counting procedure and will be a valuable tool in microbiological laboratories.

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Phosphorous (P) fractionation of the surficial sediment of high altitude lakes (HAL) i.e. P.T.Tso and Sella lakes of Arunachal Pradesh State, India were studied with an objective to investigate the phosphorus availability in the environment, nutrient status of the lake and the role of climate change. Moreover, the variation in phosphorous fraction was investigated through mineralogical studies like grain size analysis and X-ray diffraction. The findings revealed that the surficial sediment of lakes are least influenced by anthropogenic sources, since a slight increase in each of the P-Fractions was observed from year 2011 to 2012, except organic P. Loosely sorbed exchangeable phosphorous was found to be slightly high which was due to difference in atmospheric precipitation, which is one of the strong factors in high altitude regions. Decrease in organic fraction of P indicated that lakes became more oligotrophic in nature. Mineralogical investigation shows that illite-montmorillonite and montmorillonite are the main minerals in Sella Lake, whereas montmorillonite and graphite are main minerals in P.T.Tso lake. Factor analysis of seasonal data of P fractionation in surface sediments, along with physical parameters of Sella Lake water indicates three factors for the 2011 data principle factors are pH, EC, oxide-bound and organic P. Factor analysis of P.T.Tso lake water indicates three factors for the 2011 data with principle factors are adsorbed P and authigenic P, pH, oxide-bound P. This study shows that except organic fractions all other fractions are increasing in the following year. It implies that even at such remote high altitude locations P characteristics are changing year to year which sought for further investigation and enables HALs to show the early impacts of climate change related changes. A clear influence of long range transported air pollutants has been found through HYSPLIT back trajectory models which needs to be substantiated through long-term monitoring.

A low-cost extended arc thermal plasma heating (EATPH) source has been used for the sintering of Al-Zr high-temperature ceramic oxides, and their dielectric properties have been studied. Pellets of Al-Zr composites were sintered using optimum sintering parameters such as sintering time, plasma power and plasmagen gas flow rate in an EATPH reactor. Samples of similar composites were also sintered using a conventional resistive heating furnace at 1500°C for 20 h, and their dielectric properties were studied and compared with the plasma sintered sample. Sintered pellets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and dielectric measurement, carried out as a function of frequency and temperature. Highly dense sintered products were obtained by the plasma heating route within a very short sintering time compared with the conventional sintering schedule. Dielectric measurements (both dielectric constant and loss factor) showed a significant reduction in the dielectric constant, K, at room temperature under different test frequencies and also as a function of temperature. However, the change in dielectric loss factor, tan Δ, was not as pronounced as the change in K. The behaviour of the K and tan Δ curves changes drastically compared with the conventional sintered material. The reduction in K and the crossover behaviour of tan Δ in the plasma sintered specimen may be due to the action of non-reactive Ar plasmagen gas during plasma sintering, which favours mobile oxygen for the polarization network under the influence of frequency and temperature.

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