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Effects of winter and summer-time irrigation over Gangetic Plain on the mean and intra-seasonal variability of Indian summer monsoon
No full textThe decreasing trend in rainfall in the last few decades over the Indo-Gangetic Plains of northern India as observed in ground-based observations puts increasing stress on groundwater because irrigation uses up to 70 of freshwater resources. In this work, we have analyzed the effects of extensive irrigation over the Gangetic Plains on the seasonal mean and intra-seasonal variability of the Indian summer monsoon, using a general circulation model and a very high-resolution soil moisture dataset created using extensive field observations in a state-of-the-art hydrological model. We find that the winter-time (November�March) irrigation has a positive feedback on the Indian summer monsoon through large scale circulation changes. These changes are analogous to a positive North Atlantic Oscillation (NAO) phase during winter months. The effects of the positive NAO phase persist from winter to spring through widespread changes in surface conditions over western and central Asia, which makes the pre-monsoon conditions suitable for a subsequent good monsoon over India. Winter-time irrigation also resulted in a reduction of low frequency intra-seasonal variability over the Indian region during the monsoon season. However, when irrigation is practiced throughout the year, a decrease in June�September precipitation over the Gangetic Plains, significant at 95 level, is noted as compared to the no-irrigation scenario. This decrease is attributed to the increase in local soil moisture due to irrigation, which results in a southward shift of the moisture convergence zone during the active phase of monsoon, decreasing its mean and intraseasonal variability. Interestingly, these changes show a remarkable similarity to the long-term trend in observed rainfall spatial pattern and low-frequency variability. Our results suggest that with a decline in the mean summer precipitation and stressed groundwater resources in the Gangetic Plains, the water crisis could exacerbate, with irrigation having a weakening effect on the regional monsoon
Understanding Structural Variations in Elastic Organic Crystals by in Situ High-Pressure Fourier Transform Infrared Spectroscopy and Nanoindentation Study
No full textOrganic crystals possessing elasticity are gaining wide attention due to their potential applications in technology. From a design perspective, it is of utmost importance to understand the mechanical behavior of these crystals and their ability to handle stress. In this paper, we present an in situ high-pressure Fourier transform infrared spectroscopy study on 2,5-dichloro-N-benzylidene-4-chloroaniline (DPA) and 2,6 dichloro-N-benzylidene-4-fluoro-3-nitro aniline (DFA) crystals at pressures ranging from ambient pressure to 21.5 and 14.5 GPa respectively along with nanoindentation studies, at room temperature. The infrared stretching wavenumber of the aromatic and aliphatic C-H, H-C=N, and C-Cl bands on compression showed blueshifts and increased widths, which reflect structure perturbation caused by changes in intermolecular interactions in the crystals. It was noted that both crystals DPA and DFA behave in a different fashion under high-pressure prompting the derivation of different models based on structural changes in the lattice. Further, nanoindentation studies corroborated pressure-induced molecular movement in both crystals. © Copyright 2019 American Chemical Society
A Peptide-Nanoparticle System with Improved Efficacy against Multidrug Resistant Bacteria
No full textThe recent rise of multidrug resistant microbial strains requires development of new and novel therapeutic alternatives. In this study, we present a novel antibacterial system that comprises of modified naturally abundant antimicrobial peptides in conjugation with silver nanoparticles. Further, we propose a simple route to incorporate a cysteine residue either at the N- or C-terminal of the parent peptide. Tagging a cysteine residue at the terminals not only enhances the binding propensity of the resultant peptide with the silver nanoparticle, but also increases its antimicrobial property against several pathogenic bacterial strains including K. pneumoniae. The minimum inhibitory concentration (MIC) values of the cysteine tagged nanoconjugates were obtained in the range of 5�15 μM compared to 50 μM for peptides devoid of the cysteines. The origin and mechanism of such improved activity of the conjugates were investigated using NMR spectroscopy and molecular dynamics (MD) simulations. The application of 13 C-isotope labelled media to track the metabolic lifecycle of E. coli cells provided further insights into the system. MD simulations showed that pore formation in membrane bilayer is mediated through a hydrophobic collapse mechanism. The design strategy described herein opens up new-avenues for using biocompatible nanomedicines as a potential alternative to conventional antibiotics. © 2019, The Author(s)
Measurement of radiation heat transfer in supercritical carbon dioxide medium
No full textIn this work, a novel experimental method for measurement of radiation emitted by supercritical carbon dioxide (s-CO 2 ) at high pressure and high temperature is presented. Due to high pressure conditions, use of conventional spectroscopic methods to measure radiative properties of s-CO 2 is challenging. In the present method, supercritical conditions are created in a shock tube by using carbon dioxide (CO 2 ) as the driven gas. The radiative emission by s-CO 2 is measured using a platinum based thin film sensor. The total emissivity for s-CO 2 is estimated and the value compares favourably with that predicted theoretically using a standard method available in literature. It is estimated that the total emissivity value of supercritical conditions is nearly 0.2 for the conditions studied, implying that s-CO 2 acts as a participating medium for radiation heat transfer. The outcome of this study will have significant impact on the design of heat transfer equipment such as solar thermal receivers and heat exchangers typically used in s-CO 2 based closed Brayton cycle, for which participating medium radiation heat transfer has been neglected traditionally. © 2019 Elsevier Lt
Collision Avoidance of Arbitrarily Shaped Deforming Objects Using Collision Cones
No full textIn this letter, the problem of collision avoidance of objects, which can deform by changing their shape as a function of time, is considered. There are several scenarios involving such deforming objects - examples include environments with shape-shifting robots, such as snake robots, boundaries of swarms of vehicles, and boundaries of oil spills. There is very limited work in the literature that considers dynamic environments comprising such shape changing entities. To develop conditions that predict the onset of collision for deformable objects, this letter uses the notion of collision cones in environments involving engagements between a point object and a deforming object, a circular object and a deforming object, and finally, an arbitrarily shaped object and a deforming object. The collision cone equations are subsequently embedded in a Lyapunov framework and used to develop nonlinear analytical guidance laws for collision avoidance in such environments. Simulations are performed to demonstrate the efficacy of the guidance laws. © 2016 IEEE
Effect of Mechanical Mixing in Dissimilar Friction Stir Welding of Aluminum to Titanium with Zinc Interlayer
No full textWelding of aluminum (Al) and titanium (Ti) is difficult and challenging due to their differences in chemical and physical properties, and the evolution of brittle intermetallic compounds. Formation of critical intermetallics can be minimized by using an interlayer material, which leads to ternary mechanical mixing in the weld nugget. In the present investigation, a zinc (Zn) interlayer has been used during friction stir welding (FSW) of Al�Ti. It has been found that tool offset position is one of the important parameters in controlling the amount of ternary mechanical mixing of materials. The mechanical mixing of Zn with Al and Ti alters the phase evolution and restricts the formation of the brittle Al 3 Ti intermetallic compound. The optimum tool offset exhibits a homogeneous mechanical mixing and inhibits the formation of brittle intermetallic compounds, which leads to a substantial increment in the mechanical properties of the weld. © 2019, The Indian Institute of Metals - IIM
Search for long-lived particles decaying into displaced jets in proton-proton collisions at s =13 TeV
No full textA search for long-lived particles decaying into jets is presented. Data were collected with the CMS detector at the LHC from proton-proton collisions at a center-of-mass energy of 13 TeV in 2016, corresponding to an integrated luminosity of 35.9 fb-1. The search examines the distinctive topology of displaced tracks and secondary vertices. The selected events are found to be consistent with standard model predictions. For a simplified model in which long-lived neutral particles are pair produced and decay to two jets, pair production cross sections larger than 0.2 fb are excluded at 95 confidence level for a long-lived particle mass larger than 1000 GeV and proper decay lengths between 3 and 130 mm. Several supersymmetry models with gauge-mediated supersymmetry breaking or R-parity violation, where pair-produced long-lived gluinos or top squarks decay to several final-state topologies containing displaced jets, are also tested. For these models, in the mass ranges above 200 GeV, gluino masses up to 2300-2400 GeV and top squark masses up to 1350-1600 GeV are excluded for proper decay lengths approximately between 10 and 100 mm. These are the most restrictive limits to date on these models. © 2019 CERN., for the CMS Collaboration. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3
Ti2NiCoSnSb - a new half-Heusler type high-entropy alloy showing simultaneous increase in Seebeck coefficient and electrical conductivity for thermoelectric applications
No full textA new single phase high entropy alloy, Ti2NiCoSnSb with half-Heusler (HH) structure is synthesized for the first time by vacuum arc melting (VAM) followed by ball-milling (BM). The BM step is necessary to obtain the single phase. Local electrode atom probe (LEAP) analysis showed that the elements are homogeneously and randomly distributed in the HH phase without any clustering tendency. When the BM was carried out for 1 hour on the VAM alloy, microcrystalline alloy is obtained with traces of Sn as secondary phase. When BM was carried out for 5 h, single HH phase formation is realized in nanocrystalline form. However, when the BM samples were subjected to Spark plasma sintering (SPS), secondary phases were formed by the decomposition of primary phase. Nanostructuring leads to simultaneous increase in S and sigma with increasing temperature. The micro (1 h BM-SPS) and nanocrystalline (5 h BM-SPS) alloys exhibited a power factor (S-2 sigma) of 0.57 and 1.02 mWm(-1)K(-2), respectively, at 860 K. The microcrystalline sample had a total thermal conductivity similar to bulk TiNiSn sample. The nanocrystalline alloy exhibited a ZT of 0.047 at 860 K. The microcrystalline alloy showed a ZT to 0.144 at 860 K, in comparison to the nanocrystalline alloy
On biconservative hypersurfaces in 4-dimensional Riemannian space forms
No full textIn this paper, we study biconservative hypersurfaces in Sn and Hn. Further, we obtain complete explicit classifications of biconservative hypersurfaces in 4-dimensional Riemannian space forms with exactly three distinct principal curvatures
On centrally symmetric manifolds
No full textWe introduce some methods to construct centrally symmetric triangulated manifolds. In particular, we show the existence of some infinite series of centrally symmetric triangulated manifolds. We also enumerate centrally symmetric triangulated 2-, 3-manifolds with few vertices