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Understanding the evolution of thermal fluids along the western continental margin of India using geochemical and boron isotope signatures
No full textThermal springs lined up for about 350 km along the Western coast of Maharashtra, India, have been studied for major, minor, trace and rare earth elements, along with the boron isotope ratios for selected samples, to understand their evolution pattern. These alkaline springs have discharge temperatures varying from 40 to 72 degrees C. Based on the major ion composition, it is established that most of the thermal springs are of Na(Ca)-Cl or Ca(Na)Cl type, with a few of Na-Cl(SO4) type. Only one thermal spring at Rajapur is Na-HCO3 type behavior. Trace elements concentration vary significantly e.g., Li (19-386 ppb), B (104-1362 ppb), Sr (16-13560 ppb), Rb (13-220 ppb), Cs (0.75-44 ppb) and Ba (3-2077 ppb). Chondrite-normalized REE patterns indicate a pronounced 'Eu' anomaly probably due to the involvement of plagioclase, but the effect of temperature reaching more than 250 degrees C cannot be ruled out in case of some springs. First-time study of SHB isotope (range between 2.5 parts per thousand to 27.0 parts per thousand) of the West Coast thermal fluid suggests role of leaking marine sediments in their evolution. Water-rock interaction experiments with granite, basalt and diluted seawater at elevated temperatures and pressures have given an insight into the evolution of the thermal springs. Based on all the findings, a conceptual model has been prepared, which gives an overview of the evolution of the thermal springs
Combining transition metals and transient directing groups for C-H functionalizations
No full textIn the domain of synthetic chemistry, C-H bond activation has always remained in the spotlight for researchers over the last few decades. Although different strategies have been employed to chemically trigger unactivated C-H bonds, transition metal catalyzed directing group (DG) aided C-H bond activation is the most explored pathway of all because of its ability to perform diverse site selective functional metamorphosis. Despite its popularity, tedious synthetic methodology requiring additional steps for the installation and removal of DGs from the target substrate diminishes its efficacy. However, replacement of directing groups by transient directing groups (tDGs) reduces the hurdle to a greater extent without compromising the product yield and selectivity. In this report we have depicted the intense journey of transient directing groups with three (Rh, Ru, and Pd) prevalent second row transition metals
Synthesis of Phosphine Chalcogenides Under Solvent-Free Conditions Using a Rotary Ball Mill
No full textThe mechanochemical technique of ball milling has been applied to the solventless and eco-friendly synthesis of chalcogenides (sulfide and selenide) of a variety of tertiary and aminophosphines. In most of the cases, the products are obtained in almost quantitative yields with high purity by applying a simple workup procedure without using chromatographic techniques or any other purification methods. The scope of this methodology was explored by using a range of phosphines (mono, di and tetra) to synthesize partial as well as mixed chalcogenides. The use of almost equimolar amounts of starting materials and the absence of any byproducts significantly simplifies the product isolation compared with the standard solution state reactions, thus providing a highly atom economic (100%) method with an ideal E-factor (E = 0). The solid-state reactions were monitored by P-31{H-1} NMR spectroscopy. The structures of some of the products are also confirmed by single-crystal X-ray analyses. Although most of the reactions were carried out on ca. 100-mg scale, the scaling up of the reaction did not affect the course of the reaction
Development of porous TiO2 nanofibers by solvosonication process for high performance quantum dot sensitized solar cell
No full textIn the present study, we synthesized TiO2 nanofibers (NFs) by electrospinning technique and they were subject to solvosonication process using glycerol as a pore forming agent to produce porous TiO2 NFs. The prepared porous TiO2 NFs are seen to improve the light harvesting capability as a result of enhanced light scattering inside the TiO2 NFs and offer a high surface area for maximum adsorption of pre-synthesized CdSe (similar to 4 nm) QDs. The FESEM and BET analysis were performed to confirm the surface texture and surface area of porous TiO2 NFs, respectively. Finally, QDSSCs were fabricated using these porous TiO2 NFs sensitized with CdSe QDs as the photoanode, Cu2S nanoparticles as the counter electrode and polysulfide redox couple (S2-/S-x(2-)) as the electrolyte. The porous TiO2 NFs obtained by solvosonication at the time duration of 90 min has enhanced photo current density (J(sc)) of 9.21 mA/cm(2) with high power conversion efficiency (eta) of 2.15% than the conventional TiO2 NFs (eta approximate to 1.50%)
Quantum mechanical studies on dioxin-imprinted polymer precursor composites: Fundamental insights to enhance the binding strength and selectivity of biomarkers
No full textWe present a benchmark study of binding energies for dioxin-imprinted polymer complexes. A density functional theory approach was used for screening the polymerization precursors in the rational design of molecularly imprinted polymers (MIPs). Tetrachlorodibenzo-p-dioxin (TCDD) was taken as an imprinted molecule. The geometry optimization, natural bond orbital charge, and molecular electrostatic potential of TCDD and acrylamide (AM) were studied at the M062X level and 6-31G(d,p) belonging to one of the hybrid density functional theories. The results of molecular electrostatic potential and natural bond orbital charge analysis were comparable. Among the studied functional monomersAM, methacrylic acid (MAA), itaconic acid, and vinyl pyridineAM was confirmed as the best functional monomer, because the strongest interaction (the maximum number of hydrogen bonds and the lowest binding energy) occurs between TCDD and AM. The stability property was excellent when the ratio of TCDD and AM was 1:4. The polarizable continuum model was used for solvent calculations. Computational results showed that acetonitrile plays an important role in the MIP formation, as it seems to control the size and the shape of the cavity. The atoms in molecule and Becke surface method have also been applied to understand the nature and strength of the hydrogen bonding interactions in complexes. TCDD-AM complexes were found involving C-OCl and N-HCl hydrogen bonds. Good correlations have been established between hydrogen bond lengths versus atoms in molecule topological parameter like electron density (r) and its Laplacian ?(2)(r) at the bond critical points. On ground of theoretical results, a series of MIPs were synthesized. The MIP prepared using TCDD as the template, the functional monomer (AM), and the cross-linker (TRIM) in acetonitrile solvent exhibited the highest adsorption capacity for TCDD. The maximum binding capacity of TCDD on the MIP was 3.7g/mg. This research work can provide a theoretical reference for the fabrication and characterization of novel TCDD-MIPs for environmental applications
Malaria in India: The Need for New Targets for Diagnosis and Detection of Plasmodium vivax
No full textPlasmodium vivax is a protozoan parasite that is one of the causative agents of human malaria. Due to several occult features of its life cycle, P. vivax threatens to be a problem for the recent efforts toward elimination of malaria globally. With an emphasis on malaria elimination goals, the authors summarize the major gaps in P. vivax diagnosis and describe how proteomics technologies have begun to contribute toward the discovery of antigens that could be used for various technology platforms and applications. The authors suggest areas where, in the future, proteomics technologies could fill in gaps in P. vivax diagnosis that have proved difficult. The discovery of new parasite antigens, host responses, and immune signatures using proteomics technologies will be a key part of the global malaria elimination efforts
Continuous higher order sliding mode control for a class of uncertain MIMO nonlinear systems: An ISS approach
No full textIn this article, we propose a new approach towards the design of higher order sliding mode (HOSM) control, for a class of multiple input multiple output (MIMO) uncertain nonlinear systems subject to matched and unmatched uncertainties. In the proposed method, nonlinear sliding surfaces incorporating the system initial conditions and exponential functions, which guarantee the existence of sliding mode from an initial state are utilized and appropriate control inputs are designed. The control inputs are designed to enforce second order sliding mode w.r.t the sliding variables via the use of multivariable super-twisting algorithm (STA) in finite time. The resulting sliding motion is in turn proved to be input-to-state-stable (ISS) with respect to the perturbations and unmatched uncertainties. The developed sliding mode control strategy is applied for the posture stabilization of a unicycle mobile robot. The proposed method is illustrated through simulations. (C) 2018 European Control Association. Published by Elsevier Ltd. All rights reserved
Interrelationship between electrocoalescence and interfacial tension in a high acidity crude: Effect of pH and nature of alkalinity
No full textThe efficacy of electrocoalescence is critically dependent upon the interfacial tension of the crude-water interface. This study demonstrates the effect of interfacial tension on the electrocoalescence efficiency in crudes with high acidity. The interfacial tension is estimated using spinning drop tensiometer (SDT) and electrocoalescence experiments are performed at an electric field = 1.15 kV(rms)/cm at a frequency of 50 Hz. It is observed that separation of water from the crude is hindered at high pH for two very different reasons depending upon the source of alkalinity. Calcium hydroxide induced alkalinity leads to more rigid interface, resulting in delayed electrocoalescence. On the other hand, sodium hydroxide based alkalinity leads to ultra-low tension of crude-water interface, thereby causing oil-in-water emulsion. Increase in the pH also leads to poor quality of brine resolution, in case of sodium hydroxide based alkalinity (pH = 10) we get unresolved turbid emulsion
Optimizing MapReduce for energy efficiency
No full textThe efficient use of energy is essential to address concerns of cost and sustainability. Many data centers contain MapReduce clusters to process Big Data applications. A large number of machines and fault tolerance capabilities make MapReduce clusters energy inefficient. In this paper, we present a Configurator based on performance and energy models to improve the energy efficiency of MapReduce systems. Our solution is novel as it takes into account the dependence of the performance and energy consumption of a cluster on MapReduce parameters. While this dependence is known, we are the first to model it and design a Configurator to optimize these parameter settings for maximizing the energy efficiency of MapReduce systems. Our empirical evaluations show that the Configurator can result in up to 50% improvement in the energy efficiency of typical MapReduce applications in two architecturally different clusters
New lower bounds for t-coverings
No full textFisher proved in 1940 that any 2-design with.. >.. has at least.. blocks. In 1975, Ray-Chaudhuri and Wilson generalized this result by showing that every.. -design with..... +... / 2. has at least.. (... / 2.) blocks. By combining methods used by Bose and Wilson in proofs of these results, we obtain new lower bounds on the size of.. coverings. Our results generalize lower bounds on the size of 2-coverings recently obtained by the first author