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Green Synthesis of Flower-Like BiVO4 Nanoparticles by Solution Combustion Method Using Lemon (Citrus Limon) Juice as a Fuel: Photocatalytic and Electrochemical Study
No full textBiVO4 have been proven to be one of the most promising photocatalyst for degradation of organic dyes and also exhibit good electrochemical performances in heavy metal detection. Herein, we have developed a simple, economic and low-cost combustion synthesis of BiVO4 nanoparticles using bismuth nitrate as an oxidiser, lemon (Citrus Limon) juice as fuel. The prepared nanoparticles were characterized by Powder X-ray diffractometer (PXRD), Fourier Transform-Infrared spectroscopy (FTIR), Diffused Reflectance Spectroscopy (DRS), Photoluminescence Spectroscopy (PL), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analytical techniques. Flower-like morphology BiVO4 nanoparticles were observed for higher ratio of fuel (Citrus Limon). BiVO4 nanoparticles showed an excellent photocatalytic activity towards degradation of Indigo Carmine dye in solution. Further, BiVO4 modified electrode was examined for the detection of Hg (II) using electrochemical techniques
A novel methodology for construction of driving cycles for Indian cities
No full textDriving cycle (DC) forms a critical component in several of the vehicle emissions estimation procedures. It has been observed to vary with region due to the factors relating to geography, infrastructure, vehicle class etc. However, in India, only two ``polygonal'' DCs, Indian Driving Cycle and Modified Indian Driving Cycle, are used for the emission testing of all motor vehicles for regulatory purposes. Several improvements have been made in the construction methodologies of DCs since these were last formulated. While there has been a surge of interest in this area of research in India and DCs were constructed for several Indian cities, most of the studies use ``microtrips'' as their basic construction units, some of which have used parameters with rather unintuitive interpretations, especially in the context of mixed traffic of the developing economies like India. A new construction unit is proposed in this article called ``trip segment'', along with an algorithm to extract those units from the given data and a methodology to construct driving cycles. The proposed methodology is used to construct a new DC for passenger cars in Bangalore, India, which is compared with the other existing DCs of cities in and out of India. Significant differences have been observed between the DCs, emphasizing the need for the construction of separate DCs for different vehicle classes and regions
Phase Sensitive Diffraction Sensor for High Sensitivity Refractive Index Measurement
No full textIn this study a diffraction based sensor has been developed for bio molecular sensing applications and performing assays in real time. A diffraction grating fabricated on a glass substrate produced diffraction patterns both in transmission and reflection when illuminated by a laser diode. We used zeroth order I-(0,I-0) as reference and first order I-(0,I-1) as signal channel and conducted ratiometric measurements that reduced noise by more than 50 times. The ratiometric approach resulted in a very simple instrumentation with very high sensitivity. In the past, we have shown refractive index measurements both for bulk and surface adsorption using the diffractive self-referencing approach In the current work we extend the same concept to higher diffraction orders. We have considered order I-(0,I-1) and I-(1,I-1) and performed ratiometric measurements I-(0,I-1)/I-(1,I-1) to eliminate the common mode fluctuations. Since orders I((0,1) )and I-(1,I-1) behaved opposite to each other, the resulting ratio signal amplitude increased more than twice compared to our previous results. As a proof of concept we used different salt concentrations in DI water. Increased signal amplitude and improved fluid injection system resulted in more than 4 times improvement in detection limit, giving limit of detection 1.3x10(-7) refractive index unit (RIU) compared to our previous results. The improved refractive index sensitivity will help significantly for high sensitivity label free bio sensing application in a very cost-effective and simple experimental set-up
Structural insights into the specificity and catalytic mechanism of mycobacterial nucleotide pool sanitizing enzyme MutT2
No full textMis-incorporation of modified nucleotides, such as 5-methyl-dCTP or 8-oxo-dGTP, in DNA can be detrimental to genomic integrity. MutT proteins are sanitization enzymes which function by hydrolyzing such nucleotides and regulating the pool of free nucleotides in the cytoplasm. Mycobacterial genomes have a set of four MutT homologs, namely, MutTl, MutT2, MutT3 and MutT4. Mycobacterial MutT2 hydrolyzes 5 m-dCTP and 8-oxo-dGTP to their respective monophosphate products. Additionally, it can hydrolyze canonical nucleotides dCTP and CTP, with a suggested role in sustaining their optimal levels in the nucleotide pool. The structures of M. smegmatis MutT2 and its complexes with cytosine derivatives have been determined at resolutions ranging from 1.10 angstrom to 1.73 angstrom. The apo enzyme and its complexes with products (dCMP, CMP and 5 m-dCMP) crystallize in space group P2(1)2(1)2, while those involving substrates (dCTP, CTP and 5 m-dCTP) crystallize in space group P2(1). The molecule takes an alpha/beta/alpha sandwich fold arrangement, as observed in other MutT homologs. The nucleoside moiety of the ligands is similarly located in all the complexes, while the location of the remaining tail exhibits variability. This is the first report of a MutT2-type protein in complex with ligands. A critical interaction involving Asp116 confers the specificity of the enzyme towards cytosine moieties. A conserved set of enzyme-ligand interactions along with concerted movements of important water molecules provide insights into the mechanism of action
An overview of a novel use of shockwaves to alter cell permeability Comment on ``Shock wave-induced permeabilization of mammalian cells'' by Luz M. Lopez-Marin et al.
No full textMarkovnikov-Selective Co(I)-Catalyzed Hydroboration of Vinylarenes and Carbonyl Compounds
No full textAn NHC-supported Co(I) catalyst has been developed for selective Markovnikov hydroboration of vinylarenes under mild reaction conditions. The hydroboration allows highly selective synthesis of a wide range of secondary and tertiary alkyl boronates in excellent yields. Our protocol also enables hydroboration of aldehydes and ketones with diverse functional groups to access the corresponding borate esters
Cost-benefit Analysis of Public Clouds for offloading in-house HPC Jobs
No full textThe Supercomputing Education and Research Centre (SERC) at the Indian Institute of Science (IISc), located in the South East Asian Region, has been providing state-of-the-art services and support for High Performance Computing (HPC) for the academic users of the institute since 1990. This centre, facilitates OpenMP, MPI, CUDA and OpenCL based HPC jobs for academic research. To augment or support the existing demand for compute intensive, tightly coupled HPC workloads in the institute, it was desirable to explore cloud based HPC services. This study is a comparative cost-benefit analysis of the in-house compute facility at SERC with that of the commercial cloud providers like Amazon, Google Cloud, Microsoft Azure and Sabalcore. The Total Cost of Ownership (TCO) of SahasraT (the in-house supercomputer) is computed and used to identify the cost of running a small job for 24 hours on the in-house facility. This is then compared with the estimated cost of running the same job on comparative cloud instances. Several research papers that provide a detailed evaluation of HPC on the cloud with performance benchmarks and the comparison to in-house HPC facilities, were studied. These references have been used to compare performance of compute instance in the public cloud to the performance of HPC at SahasraT. The results obtained in this study, advocate that current cloud platforms are expensive in both cost and performance as compared to the in-house facility at SER
Afuronto: A six hop peer-to-peer network of zillions of Nodes
No full textWe present, in this paper, a new overlay network design that is suited for large scale peer-to-peer networks requiring fast message transmission. We particularly address the problem of designing an overlay communication network that spans across a set of data centres located in multiple geographic locations with the necessity of requiring locality properties for applications. Our design for the overlay network is motivated by the social network structures and we use different operators as found in evolutionary computing to emulate a semi-structured network.We present the network structure and the various algorithms required for basic communication and maintenance. We also study the proposed network by simulation and compare with existing overlay networks. The simulated results show that on an average there are at most six hops required for a message originated at any node in the network to be transferred to any other node in the network. The network so designed is scalable, and resilient to failure and, can include node of arbitrary in processing capacity, network bandwidth and storage
Stochastic generation of precipitation fraction at high resolution with a multiscale constraint from satellite observations
No full textIn this work, we propose a method to generate an ensemble of equiprobable fields of rain occurrence at high resolution (1 degrees/16 and 30 min) using a satellite observational constraint. Satellite observations are used to constrain the spatio-temporal variations of the precipitation fraction at various scales. Spatio-temporal averages at scales coarser than 1 degrees and 8 h are deterministically derived from the satellite observations. At finer scales, variations are partially stochastically generated by perturbation of wavelet coefficients obtained through a three-dimensional discrete Haar wavelet orthogonal decomposition. The proposed method can be viewed either as stochastic weather generation or as stochastic downscaling with a multiscale observational constraint. The observational constraint used here is a high-resolution precipitation index derived from infrared cloud top temperature. As a proof of concept, the method is used here to generate a 300-member annual ensemble covering a 12,000 km(2) area in Burkina Faso in West Africa, with a parametrization derived from ground radar observations. The stochastically generated fields aim at reproducing the multiscale statistical properties of the true precipitation field (as observed by a ground radar). The ensemble mean is an optimal - in terms of mean squared error - estimation of the true precipitation fraction, with the uncertainty quantified by the ensemble dispersion
RF Energy Harvesting For Self Powered Sensor Platform
No full textThis work demonstrates a RE powered sensor platform where energy can be available either in ambient FM band or emitted from a dedicated RF source. We realized the requirement with a dedicated chip built for RF power harvesting and conditioning A switched capacitor based ultra low power DC-DC boost converter is designed in 130nm CMOS technology as energy harvesting circuitry for ambient RF. The on-chip RE-DC resulted in a maximum efficiency of 44% with 9.75k Omega resistive load. At input sensitivities of -16dBm over 8 dominant frequencies, the sensor platform with strain gauge as sensor advertised a BEE packet every 20 minutes. For dedicated emitted radiations, the designed hybrid system is powered using sub-1 GHz frequencies. The resulting system has an end-to-end system efficiency of 9.1% and packet transmission interval of 90 seconds