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Anthropogenic fine aerosols dominate the wintertime regime over the northern Indian Ocean
No full textThis study presents and evaluates the most comprehensive set to date of chemical, physical and optical properties of aerosols in the outflow from South Asia covering a full winter (Nov. 2014 - March 2015), here intercepted at the Indian Ocean receptor site of the Maldives Climate Observatory in Hanimaadhoo (MCOH). Cluster analysis of air-mass back trajectories for MCOH, combined with AOD and meteorological data, demonstrate that the wintertime northern Indian Ocean is strongly influenced by aerosols transported from source regions with three major wind regimes, originating from the Indo-Gangetic Plain (IGP), the Bay of Bengal (BoB) and the Arabian Sea (AS). As much as 97 +/- 3% of elemental carbon (EC) in the PM10 was also found in the fine mode (PM2.5). Other mainly anthropogenic constituents such as organic carbon (OC), non-sea-salt (nss) -K+, nss-SO42- and NH4+ were also predominantly in the fine mode (70-95%), particularly in the air masses from IGP. The combination at this large-footprint receptor observatory of consistently low OC/EC ratio (2.0 +/- 0.5), strong linear relationships between EC and OC as well as between nss-K+ and both OC and EC, suggest a predominance of primary sources, with a large biomass burning contribution. The particle number-size distributions for the air masses from IGP and BoB exhibited clear bimodal shapes within the fine fraction with distinct accumulation (0.1m<d<1m) and Aitken (0.025m<d<0.10m) modes. This study also supports that IGP is a key source region for the wider South Asia and nearby oceans, as defined by the criteria that anthropogenic AODs exceed 0.3 and absorption AOD>0.03. Taken together, the aerosol pollution over the northern Indian Ocean in the dry season is dominated by a well-mixed long-range transported regime of the fine-mode aerosols largely from primary combustion origin
Bumping sequences and multispecies juggling
No full textBuilding on previous work by four of us (ABCN), we consider further generalizations of Warrington's juggling Markov chains. We first introduce ``multispecies'' juggling, which consist in having balls of different weights: when a ball is thrown it can possibly bump into a lighter ball that is then sent to a higher position, where it can in turn bump an even lighter ball, etc. We both study the case where the number of balls of each species is conserved and the case where the juggler sends back a ball of the species of its choice. In this latter case, we actually discuss three models: add-drop, annihilation and overwriting. The first two are generalisations of models presented in (ABCN) while the third one is new and its Markov chain has the ultra fast convergence property. We finally consider the case of several jugglers exchanging balls. In all models, we give explicit product formulas for the stationary probability and closed form expressions for the normalisation factor if known. (C) 2018 Elsevier Inc. All rights reserved
New tetrameric forms of the rotavirus NSP4 with antiparallel helices
No full textRotavirus nonstructural protein 4, the first viral enterotoxin to be identified, is a multidomain, multifunctional glycoprotein. Earlier, we reported a Ca2+-bound coiled-coil tetrameric structure of the diarrhea-inducing region of NSP4 from the rotavirus strains SA11 and I321 and a Ca2+-free pentameric structure from the rotavirus strain ST3, all with a parallel arrangement of alpha-helices. pH was found to determine the oligomeric state: a basic pH favoured a tetramer, whereas an acidic pH favoured a pentamer. Here, we report two novel forms of the coiled-coil region of NSP4 from the bovine rotavirus strains MF66 and NCDV. These crystallized at acidic pH, forming antiparallel coiled-coil tetrameric structures without any bound Ca2+ ion. Structural and mutational studies of the coiled-coil regions of NSP4 revealed that the nature of the residue at position 131 (Tyr/His) plays an important role in the observed structural diversity
Communication-Electrochemical Investigation of Plate-Like Na2/3Fe1/2Mn1/2O2 for Sodium Ion Cathode
No full textSodium ion batteries with low cost and high capacities have attracted much attention. Herein, P2-type Na2/3Fe1/2Mn1/2O2 is synthesized by self-combustion method and characterized for physicochemical and electrochemical properties. The XRD confirms that the sample is formed in a pure phase. Cyclic voltammograms of electrodes are characterized by two well-defined pairs of peaks corresponding to redox processes in two different stages. The electrochemical studies as a cathode for sodium ion batteries are investigated in the 1.5-4.2 V range using Na metal as anode. An initial discharge capacity of about 210 mAh g(-1) is obtained at C/10 rate. (C) 2018 The Electrochemical Society
Microstructural characterization of field assisted sintered bulk nanostructured V-4Cr-4Ti alloys
No full textThis article deals with synthesis of single-phase bulk nanostructured V-4Cr-4Ti alloy by mechanical alloying and field assisted sintering. Mechanically alloyed powders were sintered at 1050 and 1100 degrees C with different sintering time. Both powder and sintered samples were subjected to structural and morphological characterization using x-ray diffraction and electron microscopy studies. x-ray diffraction and transmission electron microscopy studies of sintered samples confirm that field assisted sintering technique aids nanostructuring in V-4Cr-4Ti alloy. Microstructural parameters of sintered samples were calculated from x-ray diffraction patterns. Role of sintering variables on the microstrain evolution and subsequent domain size reduction in bulk V-4Cr-4Ti alloy are briefly discussed. Optimal sintering parameters to achieve nanostructured V-4Cr-4Ti alloy by field assisted sintering were deduced. Micro-hardness and relative density of sintered V-4Cr-4Ti alloy are found to increase with sintering temperature and sintering time
On the Power of Hybrid Networks in Multi-Party Computation
No full textPerfectly-secure verifiable secret sharing (VSS) and multi-party computation (MPC) protocols in asynchronous network tolerate only at most one-fourth of corruption, while their counterparts in synchronous network sustain against at most one-third corruption. Moreover property-wise, synchronous protocols provide much stronger guarantees than the asynchronous counterparts. Taking note of the fact that asynchronous network is more realistic on one hand and on the other, synchrony of a network has positive impact on several aspects of distributed protocols including properties and fault-tolerance, we explore the power of hybrid networks that combines best of both the worlds by supporting a few synchronous rounds at the onset of a protocol execution, before turning to asynchronous mode. In hybrid networks, we investigate various feasibility questions pertaining to protocols giving guarantees attainable in synchronous and asynchronous networks. For the asynchronous protocols in hybrid networks, we hope to leverage the initial synchronous rounds to bridge the gap in the fault-tolerance with the synchronous protocols under minimal synchrony assumption. We ask the following fundamental question of both theoretical and practical importance: What is the minimum number of initial synchronous rounds necessary and sufficient in a hybrid network to construct asynchronous perfectly-secure VSS and MPC protocols with the fault-tolerance of synchronous protocols? On the positive note, we show that the answer is one for VSS which is clearly optimal. Notably no broadcast oracle is invoked in the synchronous round of our proposed VSS protocol. On the negative side, we prove that one synchronous round is not enough for MPC, putting MPC on a higher pedestal than VSS in terms of difficulty. For synchronous protocols in hybrid networks, we hope to save on the synchronous rounds leveraging conveniently the available asynchronous phase. We settle the question for VSS in the negative showing that three rounds that are known to be necessary (and sufficient) for VSS in synchronous networks, are also required in hybrid networks. VSS being a special case of MPC, the lower bound holds true for MPC. We match the lower bound with a three-round protocol. Notably, synchronous MPC with cryptographic security is known to be achievable in hybrid networks with one synchronous round
Strong sea forcing and warmer winter during solar minima similar to 2765 yr BP recorded in the growth bands of Crassostrea sp. from the confluence of river Ganges, Eastern India
No full textLong term variation of solar activity plays a key role in controlling climatic oscillations during glacial interglacial cycles. The records of such climatic shifts can be retrieved from sedimentary archives in overbank deposits found in the estuary regions of major rivers in the tropics which are fed by glaciers. In this study we have shown the effect of solar variability on regional climate by altering the river discharge and incursion of warm water pool into the region adjoining Bay of Bengal during seasonal dry period. The incremental growth bands present in the modern day Meretrix sp and Late Holocene Crassostrea sp. were examined for reconstruction of temperature and water composition at the head bay region of the river Ganges. The conventional C-14 techniques on fossil oyster yielded age of 2765 +/- 130 yr B . P., which coincides with a solar minima. Analysis of clumped isotope thermometry on the growth bands provided temperature estimates for the growth of shells. The temperature estimates for the modern shell, suggesting range of values showed a range between 13 degrees and 42 degrees C, close to the observed temperatures recorded in the climatological data while the fossil shell had a range of values between 22 degrees and 38 degrees C. The 8180 measured in the aragonite together with the estimated temperature were used to deduce the water composition during growth at equilibrium condition. The water 8180 varied between -4.8 parts per thousand and 1.2 parts per thousand for the modern sample, close to the observed values of water measured near this locality, while the range in water composition inferred for the paleo samples was from 2.37%0 to 0.82 parts per thousand,, suggesting a stronger influence of sea water throughout the year. The results are consistent with the argument of infiltration of water from neighbouring warm water pool into the estuary. A similar approach can be extended to evaluate the effects of climate variability due to differential action of river discharge into the sea at seasonal time scales based on available mollusc shells in the sedimentary successions from the region. (C) 2017 Elsevier Ltd and INQUA. All rights reserved
Supercapacitive performance of electrochemically synthesized nanocrystalline MnO2 films using different plating solutions: A comparative study
No full textIn this paper we report the comparative supercapacitive performance of the electrodeposited MnO2 films prepared using different plating solutions, namely KMnO4, MnSO4 and Mn(CH3COO)(2). All the MnO2 films possess the hexagonal phase of epsilon manganese dioxide (epsilon-MnO2, akhtenkite), consistent with the JCPDS card no. 12-0141. The analyses of SEM images reveal that the electrodeposited MnO2 film prepared from the plating solution KMnO4 has a porous microstructure comprising of sparsely distributed grains, whereas that prepared from MnSO4 has a uniform morphology covered with nanofibers having porous spaces between them, and that prepared using Mn(CH3COO)(2) exhibits a dense morphology comprising of nanofibres. The galvanostatic charge/discharge measurements show the maximum specific capacitance 325.6 F/g for the MnO2 film prepared using KMnO4, followed by 275.2 F/g and 174.5 F/g for the films prepared by MnSO4 and Mn(CH3COO)(2)., respectively. The variation in specific capacitances of the films is attributed to varying morphological features of the films. (X) 2018 Elsevier B. V. All rights reserved
Volume change behaviour of swelling and non-swelling clays upon inundation with water and a low dielectric constant fluid
No full textStudies of the volume change behaviour of saturated and unsaturated fine-grained soils upon exposure to various types of fluid are of significant interest while dealing with contaminated soils. In this study, the one-dimensional volume change behaviour of two clays (Spergau kaolin and Calcigel bentonite) with dominant minerals as kaolinite and montmorillonite was studied by inundating several initially unsaturated and saturated clay specimens with water and a non-polar organic liquid (heptane). For both cases, applied vertical pressures of 25 and 1001kPa were considered under oedometric conditions. The magnitude of compression and swelling deformations of the clays were found to be strongly dependent upon the mineralogy of clays, dielectric properties of the pore-fluid, initial compaction conditions, and applied stress during the wetting process. The test results indicated distinct interactions between unsaturated clays and water. Specimens of Spergau kaolin exhibited compression with water, whereas specimens of Calcigel bentonite exhibited swelling. Compression and swelling deformations of the clays with heptane as the inundating liquid remained within about 1.0% for both clays indicating a very minor interaction between unsaturated clays and molecules of this non-polar organic liquid. The test results emphasized the significance of attractive and repulsive forces and their impact on the volume change behaviour of clays of different mineralogy
Zn(II), Cd(II) and Hg(II) metal complexes of 2-aminonicotinaldehyde: Synthesis, crystal structure, biological evaluation and molecular docking study
No full textIn this report, the ligand, 2-aminonicotinaldehyde (ANA) and its metal complexes Zn(ANA)(2)Cl-2], Cd (ANA)(2)Cl-2] and Hg(ANA)(2)Cl-2] have been synthesized and characterized by analytical and various spectroscopic (IR, Electronic, H-1 and C-13 NMR) studies. The single crystal X-ray diffraction studies of ANA and Zn(ANA)(2)Cl-2] complex have been discussed. It was found that intra/intermolecular hydrogen bonding exists in both compounds and N-atom of pyridine ring of ANA coordinated to the metal ion in tetrahedral fashion. Metal chlorides, ANA and its complexes were subjected to biological screening, antioxidant, in vitro cytotoxicity and EGFR (Epidermal growth factor receptor) targeting molecular docking studies which indicated the synergistic effect of metal complexes on the biological activity than the free ligand and metal chlorides. (C) 2017 Elsevier B.V. All rights reserved