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Metal Complex as an Optical Sensing Platform for Rapid Multimodal Recognition of a Pathogenic Biomarker in Real-Life Samples
No full textAnthraimidazoledione-based charge transfer dyes have been designed for multimodal detection of a pathogenic biomarker, dipicolinic acid (DPA), at physiological pH. A change in visible color from yellow to red was observed along with an appearance of red luminescence when the probe-Eu3+ complex was exposed to DPA. Conversely, with the probe-Cu2+ complex, the solution color turns into orange in the presence of DPA with blue-colored fluorescence. Thus, the present sensory system can achieve naked-eye detection of DPA, which is very rare for metal complex-based probes. Mechanistic investigations revealed that variations in the metal ion center influence the nature of the DPA interaction, which subsequently dictates the output optical signal. DPA forms a ternary complex with the probe-Eu3+ conjugate, while in the case of Cu2+, it dissociates the preformed probe-metal ion conjugate. Interestingly, at a given concentration of DPA, the probe with the 2,2'-(phenylazanediyl)diacetic acid group (1) at the receptor end shows a more prominent change with DPA as compared to the probe with the 2,2'-((2-(carboxymethoxy)phenyl)azanediyl)diacetic acid (2) functional group. Subsequently, the system is involved in the screening of DPA in complex real-life samples, such as human blood serum, urine, natural water and soil samples, etc. In addition, the present assay can be employed for quantitative evaluation of Bacillus subtilis spores, and as low as 2.2 x 10(4) spores/mL was detected. Further, to extend the practical implication, low-cost paper-based devices are developed as an eco-friendly alternative for on-location detection of DPA
Search for Higgs boson pair production in the gamma gamma b(b)over-bar final state in pp collisions at root s=13 TeV
No full textA search is presented for the production of a pair of Higgs bosons, where one decays into two photons and the other one into a bottom quark-antiquark pair. The analysis is performed using proton-proton collision data at root s = 13 TeV recorded in 2016 by the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb(-1) . The results are in agreement with standard model (SM) predictions. In a search for resonant production, upper limits are set on the cross section for new spin-0 or spin-2 particles. For the SM-like nonresonant production hypothesis, the data exclude a product of cross section and branching fraction larger than 2.0 fb at 95% confidence level (CL), corresponding to about 24 times the SM prediction. Values of the effective Higgs boson self-coupling K X are constrained to be within the range -11 < K-lambda < 17 at 95% CL, assuming all other Higgs boson couplings are at their SM value. The constraints on K-lambda, are the most restrictive to date. (C) 2018 The Author(s). Published by Elsevier B.V
Moored Observations of the Surface Meteorology and Air-Sea Fluxes in the Northern Bay of Bengal in 2015
No full textTime series of surface meteorology and air-sea fluxes from the northern Bay of Bengal are analyzed, quantifying annual and seasonal means, variability, and the potential for surface fluxes to contribute significantly to variability in surface temperature and salinity. Strong signals were associated with solar insolation and its modulation by cloud cover, and, in the 5- to 50-day range, with intraseasonal oscillations (ISOs). The northeast (NE) monsoon (DJF) was typically cloud free, with strong latent heat loss and several moderate wind events, and had the only seasonal mean ocean heat loss. The spring intermonsoon (MAM) was cloud free and had light winds and the strongest ocean heating. Strong ISOs and Tropical Cyclone Komen were seen in the southwest (SW) monsoon (JJA), when 65% of the 2.2-m total rain fell, and oceanic mean heating was small. The fall intermonsoon (SON) initially had moderate convective systems and mean ocean heating, with a transition to drier winds and mean ocean heat loss in the last month. Observed surface freshwater flux applied to a layer of the observed thickness produced drops in salinity with timing and magnitude similar to the initial drops in salinity in the summer monsoon, but did not reproduce the salinity variability of the fall intermonsoon. Observed surface heat flux has the potential to cause the temperature trends of the different seasons, but uncertainty in how shortwave radiation is absorbed in the upper ocean limits quantifying the role of surface forcing in the evolution of mixed layer temperature
RANDOMIZED ALGORITHMS FOR STABILIZING SWITCHING SIGNALS
No full textQualitative behaviour of switched systems has attracted considerable research attention in the recent past. In this article we study `how likely' is it for a family of systems to admit stabilizing switching signals. A weighted digraph is associated to a switched system in a natural fashion, and the switching signal is expressed as an infinite walk on this digraph. We provide a linear time probabilistic algorithm to find cycles on this digraph that have a desirable property (we call it ``contractivity''), and under mild statistical hypotheses on the connectivity and weights of the digraph, demonstrate that there exist uncountably many stabilizing switching signals derived from such cycles. Our algorithm does not require the vertex and edge weights to be stored in memory prior to its application, has a learning/exploratory character, and naturally fits very large scale systems
Toward understanding cancer stem cell heterogeneity in the tumor microenvironment
No full textThe epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) formation are two paramount processes driving tumor progression, therapy resistance, and cancer metastasis. Recent experiments show that cells with varying EMT and CSC phenotypes are spatially segregated in the primary tumor. The underlying mechanisms generating such spatiotemporal dynamics in the tumor microenvironment, however, remain largely unexplored. Here, we show through a mechanism-based dynamical model that the diffusion of EMT-inducing signals such as TGF-beta, together with noncell autonomous control of EMT and CSC decision making via the Notch signaling pathway, can explain experimentally observed disparate localization of subsets of CSCs with varying EMT phenotypes in the tumor. Our simulations show that the more mesenchymal CSCs lie at the invasive edge, while the hybrid epithelial/mesenchymal (E/M) CSCs reside in the tumor interior. Further, motivated by the role of Notch-Jagged signaling in mediating EMT and sternness, we investigated the microenvironmental factors that promote Notch-Jagged signaling. We show that many inflammatory cytokines such as IL-6 that can promote Notch-Jagged signaling can (i) stabilize a hybrid E/M phenotype, (ii) increase the likelihood of spatial proximity of hybrid E/M cells, and (iii) expand the fraction of CSCs. To validate the predicted connection between Notch-Jagged signaling and sternness, we knocked down JAG1 in hybrid E/M SUM149 human breast cancer cells in vitro. JAG1 knockdown significantly restricted tumor organoid formation, confirming the key role that Notch-Jagged signaling can play in tumor progression. Together, our integrated computational-experimental framework reveals the underlying principles of spatiotemporal dynamics of EMT and CSCs
Design of a Do-It-Yourself (DIY) based Solar Powered LED Lighting System for Training and Empowering Rural youth
No full textDo-It-Yourself (DIY) approach is an effective pedagogy method for providing learning experience to the user. The DIY approach also gives a sense of ownership (and empowerment) to the people as they assemble the product themselves. It also provides a vocational training platform for innovative ideas
of people by extending the applicability and its realization.
The design of ‘Roshini’, a DIY model for solar powered reliable lighting system aims at improving the adoption of improved sanitation practices, and sensitizing the community, through the youth, on good hygiene practices. Roshini also
addresses the issue of lack of safe, well-lit sanitation access, lack of power supply for mobile phone charging and other basic daily needs which require electricity.The paper discusses the design approach towards the proposed development of
‘Roshini’ – A DIY based solar powered LED lighting system
Peridynamics model for flexoelectricity and damage
No full textA flexoelectric peridynamic (PD) theory is proposed. In the PD framework, the formulation introduces a nanoscale flexoelectric coupling that entails non-uniform strain in centrosymmetric dielectrics. This potentially enables PD modeling of a large class of phenomena in solid dielectrics involving cracks, discontinuities etc. wherein large strain gradients are present and the classical electromechanical theory based on partial differential equations do not directly apply. PD electromechanical equations, derived from Hamilton's principle, satisfy the global balance laws. Linear PD constitutive equations reflect the electromechanical coupling effect, with the mechanical force state affected by the polarization state and the electrical force state in turn by the displacement state. An analytical solution to the PD electromechanical equations is presented for the static case when a point mechanical force and a point electric force act in an infinite 3D solid dielectric. A parametric study on how different length scales influence the response is undertaken. In addition, the model is extended to incorporate damage using phase field - an order parameter, supplemented with a PD bond breaking criterion to study flexoelectric effects in damage and fracture problems. To demonstrate the performance of our proposal, we first simulate, considering small flexoelectricity effect and no damage, an externally pressured 2D flexoelectric disk subjected to a potential difference between the inner and outer surfaces and compare the results with existing solutions in the literature. Next, we simulate a plate with a central pre-crack under tension considering damage and flexoelectricity effects, and study the effect of various constitutive parameters on the damage evolution. We also furnish a classical derivation of phase field based flexoelectricity in Appendix 1. (C) 2018 Elsevier Inc. All rights reserved
Microstructure-electrochemical property correlation in electrodeposited CuFeNiCoCr high-entropy alloy-graphene oxide composite coatings
No full textThis study investigates the microstructure-electrochemical property correlation in high-entropy alloy-graphene oxide (HEA-GO) composite coatings. HEA coating containing Cu, Fe, Cr, Co, and Ni was electrodeposited over mild steel. Graphene oxide (GO) content in the coating was varied by changing the amount of GO in the electrolyte bath during the electrodeposition. Corrosion behaviour of the coatings was examined through potentiodynamic polarisation and electrochemical impedance spectroscopy methods. It was observed that with an increase in the GO amount, the corrosion resistance of HEA-GO composite coatings progressively increased. Microstructural charaterisation, using the transmission electron microscopy technique, revealed that the addition of GO enhanced the amount of Cr in the coatings and also produced a layered microstructure with Cu and Cr-rich layer covering the coating surface. Both these factors along with the impermeability of GO facilitated enhancement in the corrosion resistance. Major application areas that require protective coatings over mild steel are oil and gas pipe lines, structural components exposed to marine environments, automobiles, industrial cleaning, etc
Radial junction silicon solar cells with micro-pillar array and planar electrode interface for improved photon management and carrier extraction
No full textWe demonstrate radial p-n junction silicon solar cells with micro-pillar array with higher short-circuit current and open-circuit voltage than comparable planar silicon solar cells. Micro-pillar array, fabricated by RIE, acts as an effective anti-reflection coating for visible light with less than 6% reflection. Compared to devices with planar surface, devices with micro-pillar array show a 27% enhancement in short circuit current. The radial p-n junction of the micro-pillars also improves extraction probability of the photogenerated carriers, which further increases the short circuit current. Typically, micro-pillar solar cells suffer from high recombination losses at the Si/metal interface, resulting in poor V-oc. Our devices prevent these recombination losses by planarizing the Si/metal interface, leading to an open circuit voltage of 622 mV, the highest ever reported for micro-pillar solar cells. This planarized contact also reduces the series resistance associated with radial junctions, leading to series resistance of <= 0.50 Omega-cm(2) and fill factors up to 76.7%
Volume estimation of existing and potential glacier lakes, Sikkim Himalaya, India
No full textGlacial lake outburst floods (GLOFs) are a hazard commonly reported in the glaciated terrain of the Himalaya. Glacier lakes can form if the glaciers retreat and the bottom topography overdeepens. We have adopted a technique to estimate the depth and volume of lakes using parameters such as glacier surface velocity, slope and laminar flow of ice. The technique has been automated using Python programming language. The method was applied in the Sikkim Himalaya to map potential lake sites and also to predict further expansion of existing glacier lakes. Studies were carried out for ten glaciers in the Tista river basin. The analysis suggests nine potential lake sites, including further expansion of four existing glacier lakes. To validate the results, the model lake boundary in 2001 was compared with the satellite-observed value of 2015 and field measurements made at the South Lhonak lake. The volume of the South Lhonak lake (in 2015) was estimated as 60 +/- 10.8 million m(3); with prolonged retreat of the glacier, the lake is likely to expand to a maximum volume of 90 +/- 16.2 million m(3). The above technique can provide new information to planners, leading to a more realistic approach in understanding the disaster potential of glacier lakes