Microrheological Studies of Regenerated Silk Fibroin Solution by Video Microscopy

We have carried out studies on the rheological properties of regenerated silk fibroin (RSF) solution using video microscopy. The degummed silk from the Bombyx mori silkworm was used to prepare RSF solution by dissolving it in calcium nitrate tetrahydrate-methanol solvent. Measurements were carried out by tracking the position of an embedded micron-sized polystyrene bead within the RSF solution through video imaging. The time dependent mean squared displacement (MSD) of the bead in solution and hence, the complex shear modulus of this solution was calculated from the bead's position information. An optical tweezer was used to transport and locate the bead at any desired site within the micro-volume of the sample, to facilitate the subsequent free-bead video analysis. We present here the results of rheological measurements of the silk polymer network in solution over a frequency range, whose upper limit is the frame capture rate of our camera, at full resolution. By examining the distribution of MSD of beads at different locations within the sample volume, we demonstrate that this probe technique enables us to detect local inhomogeneties at micrometer length scales, not detectable either by a rheometer or from diffusing wave spectroscopy.Comment: 5 page

Evaluation of water quality index of the river Cauvery and its tributaries

Water quality of the river Cauvery and its tributaries - Arkavathi and Vrishabhavathi - was assessed by using Bhargava's water quality index. Significant seasonal variation was revealed by the spatially measured physico-chemical characteristics. The water quality index is categorized as class III (satisfactory range) for the Cauvery and Arkavathi rivers and class IV (poor range) for the Vrishabhavathi. The spatial homogeneity of quality was determined by using Duncan's multiple range test

Urban Expansion and Loss of Agriculture Land-A Case of Bengaluru City

The cultivated land across India has fragmented significantly resulting in change in landuse. The agricultural land has continued to shrink due to rapid urbanization. Nearly 45% land across India is cultivated area and 22% of the landuse area is forestland. The study using Remote Sensing data for the metropolitan fringe of Bengaluru reveals the expansion of built up to 446.55 sq. km by 2014. The increase in built up has reduced the agriculture land by 212.49 square kilometers. The agriculture land comprised of 27.57 square kilometers of agriculture plantation and 184.91 square kilometers of cropland. 96.29 square kilometers of agriculture land has been converted to “to-be built up” area. The 50.57% of the combined land area of built up and to-be built up is from agriculture land and the rest 49.43% from other land category. Over the years, the urban expansion to the fringes has declined the agricultural land by 16.31%. With the increase in requirement of both land and food security, it becomes imperative to protect and conserve the farmlands by policy and guidelines

Comparative Study on the Prediction of Aerodynamic Characteristics of Mini - Unmanned Aerial Vehicle with Turbulence Models

When dealing with CFD simulations the turbulent nature is seen on most of the engineering flows and these flows need to be solved. Reliable and applicable CFD outputs can be obtained from the accurate modelling of the turbulence as it is one of the most vital elements of CFD modelling. The RANS equations are extensively employed to analyse the complex flows over aircraft and for this purpose, a turbulence model is needed for turbulent flow analyses. Compatible turbulence must be chosen for the exact predictions of aircraft aerodynamic characteristics. In this report, numerical analyses of Mini-UAV are done to compare the outputs of different types of turbulence models for the prediction of aircraft aerodynamic characteristics for various flight conditions i.e., -4° to 40° at Mach number 0.04. ANSYS software is employed for this aerodynamic analysis. The six turbulence models compared are the Spalart-Allmaras, k-ɛ standard, k-ɛ RNG, k-ɛ Realizable, k-ω standard, and k-ω SST model. The impact of several turbulence models on the Mini-UAV aerodynamic performance is also studied numerically and validated with existing experimental data from reliable sources. The lift and drag coefficients for both numerical and experimental results exhibit an excellent correlation at Mach number 0.04. The recorded maximum variation of the coefficient of lift and the lift-to-drag ratio is determined to be 9.43% at a stall angle of attack (38°) and 7.01% at a 4˚ angle of attack among the six various turbulence models. The summation of deviation of coefficients of lift and drag values i.e., 0.0166 for the Spalart-Allmaras turbulence model is found to be less compared with all the other turbulence models so it can be said that the Spalart-Allmaras turbulence model is the best fit in terms of coefficients of lift and drag for Mini-UAV applications for subsonic flow

Effects of flame retardance additives on the mechanical and fire performance of natural fibre composites

The incorporation of sustainability is becoming increasingly important in manufacturing practices worldwide. This includes the development of natural fibre composites with mechanical and flammability characteristics suitable for structural interiors. Composites manufactured from kenaf fibres and polypropylene (PP) were investigated as to their suitability as materials for the interiors of buildings, aircraft and such-like. Natural fibres like kenaf act as fuel sources during combustion, and hence, flame retardants are added to the mix. In the present study, the ammonium polyphosphate (APP)-based flame retardant Budit® 3167 was used to address this issue. Limited studies exist on how the inclusion of APP influences the composites’ mechanical properties. Hence the main objective of this research project was to evaluate the effect of adding Budit 3167 on both mechanical and flammability properties of kenaf-PP composites. Kenaf-PP composites were manufactured with various fibre weight percentages, with and without Budit 3167. The composites were subjected to different experiments to assess their mechanical and flammability behaviour. It was found that Budit 3167 not only improved the flammability properties of the composites, but also the tensile and flexural moduli due to the flame retardant behaving like a particle reinforcement. However, weak interfacial bonds arising from the addition of Budit 3167 led to a decrease in mechanical strength, providing a basis for further investigation. It was concluded that kenafPP composites with Budit 3167 show good potential as a sustainable alternative for structural interiors

Microrheology of non mulberry silk varieties by optical tweezer and video microscopy based techniqueas

We have carried out a comparative study of the microrheol. properties of silk fibroin solns. formed from a variety of silks indigenous to the Indian subcontinent. We present the measured viscoelastic moduli of Tasar silk fibroin soln. using both a single and dual optical tweezer at 0.16​% and 0.25​% (w​/v)​. The bandwidth of the measurements carried out using optical tweezers is extended down to the lower frequency regime by a video microscopy measurement. Further, we have measured the viscoelastic moduli of Eri and Muga varieties of silk fibroin solns. at a higher concn. (1.00​% w​/v) limiting the tool of measurement to video microscopy, as the reduced optical transparencies of these solns. at higher concn. preclude an optical tweezer based investigation. The choice of a higher concn. of fibroin soln. of the latter silk varieties is so as to enable a comparison of the shear moduli obtained from optical methods with their corresponding fiber stiffness obtained from wide angle X-​ray scattering data. We report a correlation between the microstructure and microrheol. parameters of these silk varieties for the concn. of fibroin solns. studied

SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal

The global 21 cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR), at redshifts $z \sim 6-30$, probes the nature of first sources of radiation as well as physics of the Inter-Galactic Medium (IGM). Given that the signal is predicted to be extremely weak, of wide fractional bandwidth, and lies in a frequency range that is dominated by Galactic and Extragalactic foregrounds as well as Radio Frequency Interference, detection of the signal is a daunting task. Critical to the experiment is the manner in which the sky signal is represented through the instrument. It is of utmost importance to design a system whose spectral bandpass and additive spurious can be well calibrated and any calibration residual does not mimic the signal. SARAS is an ongoing experiment that aims to detect the global 21 cm signal. Here we present the design philosophy of the SARAS 2 system and discuss its performance and limitations based on laboratory and field measurements. Laboratory tests with the antenna replaced with a variety of terminations, including a network model for the antenna impedance, show that the gain calibration and modeling of internal additives leave no residuals with Fourier amplitudes exceeding 2~mK, or residual Gaussians of 25 MHz width with amplitudes exceeding 2~mK. Thus, even accounting for reflection and radiation efficiency losses in the antenna, the SARAS~2 system is capable of detection of complex 21-cm profiles at the level predicted by currently favoured models for thermal baryon evolution.Comment: 44 pages, 17 figures; comments and suggestions are welcom

Generation of High Voltage DC using Diodes & Capacitors in Ladder Network

The project is designed& constructed to develop a high voltage DC of around 2KV from a input AC supply source of 230V using the capacitors and diodes that are constructed in the form of ladder network based on voltage multiplier concept. Generally transformers are used for stepping up of voltage in which the output of the secondary of the step up transformer increases the voltage and decreases the current. The other method for stepping up the voltage without the use of transformers is by using voltage multiplier circuit which converts AC to DC. These Voltage multipliers are primarily used to develop high voltages where low current is required. The concept of developing high voltage DC from single Phase AC is described in this project which can be enhanced up to 10KV. For safety purpose this project is restricted with a multiplication factor of 8 so that the output would be within 2KV.This concept of generation of high voltage using multiplier circuit is used in Electronic appliances such as CRT?s, oscilloscopes and in industrial applications. The principle of voltage multiplier circuit is that the voltage keeps on doubling at each stage. Thus, the output of an 8 stage voltage multiplier circuit is 2KV DC which cannot be measured by using a standard multimeter. Hence a potential divider of 10:1 is used at the output such that 200V reading means 2KV