Bangalore, India
Bangalore, India

Indian Institute of Science is a public university for scientific research and higher education located in Bengaluru , India. Established in 1899 with active support from Jamshetji Tata it is also locally known as the "Tata Institute". It acquired the status of a Deemed University in 1958. IISc is widely regarded as India's finest institution in its field, and has made significant contribution to advanced computing, space, and nuclear technologies. Wikipedia.

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The present disclosure relates to aluminum based alloys and a method for producing the aluminium based alloys. The method comprises acts of, casting of the aluminium based alloy in a chilled casting mould. Then, aging the cast aluminium based alloy at a first predetermined temperature for a first predetermined time. The aging results in the formation of a first precipitate. Followed by this, solutionizing the aluminium based alloy at a second predetermined temperature for a second predetermined time such that the major alloying element is dissolved in aluminium matrix without much affecting the first precipitate. Then, aging the aluminium based alloy at a third predetermined temperature for a third predetermined time. The aging results in the formation of a second precipitate.

The invention discloses a method for the synthesis of monodispersed luminescent quantum dots of transition metal dichalcogenides (TMDC), single- or few-layered, using a single-step electrochemical exfoliation that involves dilute ionic liquid and water. The method disclosed helps to obtain nanoclusters of TMDC of desired size including small sizes ranging up to 6 nm, by varying the concentration of the electrolyte and the applied DC voltage. The invention further discloses a method by which mono- or few-layered luminescent transition metal dichalcogenides can be directly deposited onto conducting substrates in a uniform manner. The monodispersed single- or few-layered luminescent TMDC and electro-deposited substrates exhibit improved electronic conductivity and new active sites, making them suitable as high-performance electrocatalysts in hydrogen evolution reactions in solar water-splitting applications and also as electrodes for solar cell applications.

Indian Institute of Science | Date: 2015-03-21

Embodiments herein present the invention of a class of Tungsten (W) free Cobalt based (-) superalloys with the basic chemical composition comprising in % by weight: 0.5 to 10 Aluminium (Al) and 1 to 15 Molybdenum (Mo) with at least one or both of 0.5 to 12 Niobium (Nb) and 0.5 to 12 Tantalum (Ta), with the remainder being Cobalt (Co). Some part of the cobalt can be replaced by nickel (50% or less). In Nickel added alloys, some part of either cobalt of nickel can be replaced by at least one among the transition metal selected from the group consisting of 10% or less Iridium, 10% or less Platinum, 10% or less Palladium, 15% or less Chromium and combination thereof. Again in nickel added alloys, further addition of at least one among the transition metals zirconium (5% or less), hafnium (5% or less), vanadium (5% or less), titanium (5% or less), and yttrium (5% or less), boron (2% or less), carbon (2% or less), rhenium (10% or less), ruthenium (5% or less) for further fine tune the solvus temperature, volume fraction of and creep properties.

Raote I.,National Center for Biological science | Bhattacharyya S.,Indian Institute of Science | Panicker M.M.,National Center for Biological science
Molecular Pharmacology | Year: 2013

G protein-coupled receptor (GPCR) signaling is modulated by endocytosis and endosomal sorting of receptors between degradation and recycling. Differential regulation of these processes by endogenous ligands and synthetic drugs is a poorly understood area of GPCR signaling. Here, we describe remarkable diversity in the regulation of trafficking of GPCR induced by multiple ligands. We show that the serotonin receptor 2A (5-HT2A), a prototypical GPCR in the study of functional selectivity at a signaling receptor, is functionally selective in endocytosis and recycling in response to five ligands tested: endogenous agonists serotonin (5-HT) and dopamine (DA), synthetic agonist 1-(2,5-dimethoxy-4-iodophenyl)-aminopropane (DOI), antagonist ketanserin, and inverse agonist and antipsychotic drug clozapine. Only four ligands (5-HT, DA, DOI, and clozapine) bring about receptor endocytosis. As we have earlier described with 5-HT and DA, there is ligand-specific requirement for protein kinase C (PKC) in endocytosis. We now show 5-HT2A phosphorylation by PKC is necessary for 5-HT-mediated and DOI-mediated receptor endocytosis, but DA-mediated and clozapine-mediated internalization is not affected if PKC is inhibited. Internalized receptors are recycled to the cell surface, but there is variability in the time course of recycling. 5-HT- and DA-internalized receptors are recycled in 2.5 hours while agonist DOI and antagonist clozapine bring about recycling in 7.5 hours. Recycling in response to those ligands that require PKC activation to effect receptor endocytosis is dependent on receptor dephosphorylation by protein phosphatase 2A (PP2A). Thus, internalization and phosphorylation/dephosphorylation cycles may play a significant role in the regulation of 5-HT2A by functionally and therapeutically important ligands. Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics.

Roychoudhury S.,Indian Institute of Science
World Journal of Gastroenterology | Year: 2015

Helicobacter pylori (H. pylori ) have long been associated with a spectrum of disease outcomes in the gastro-duodenal system. Heterogeneity in bacterial virulence factors or strains is not enough to explain the divergent disease phenotypes manifested by the infection. This review focuses on host genetic factors that are involved during infection and eventually are thought to influence the disease phenotype. We have summarized the different host genes that have been investigated for association studies in H. pylori mediated duodenal ulcer or gastric cancer. We discuss that as the bacteria co-evolved with the host; these host gene also show much variation across different ethnic population. We illustrate the allelic distribution of interleukin-1B, across different population which is one of the most popular candidate gene studied with respect to H. pylori infections. Further, we highlight that several polymorphisms in the pathway gene can by itself or collectively affect the acid secretion pathway axis (gastrin: somatostatin) thereby resulting in a spectrum of disease phenotype. © The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.

Marchetti M.C.,Syracuse Biomaterials Institute | Joanny J.F.,University Pierre and Marie Curie | Ramaswamy S.,Indian Institute of Science | Liverpool T.B.,University of Bristol | And 5 more authors.
Reviews of Modern Physics | Year: 2013

This review summarizes theoretical progress in the field of active matter, placing it in the context of recent experiments. This approach offers a unified framework for the mechanical and statistical properties of living matter: biofilaments and molecular motors in vitro or in vivo, collections of motile microorganisms, animal flocks, and chemical or mechanical imitations. A major goal of this review is to integrate several approaches proposed in the literature, from semimicroscopic to phenomenological. In particular, first considered are "dry" systems, defined as those where momentum is not conserved due to friction with a substrate or an embedding porous medium. The differences and similarities between two types of orientationally ordered states, the nematic and the polar, are clarified. Next, the active hydrodynamics of suspensions or "wet" systems is discussed and the relation with and difference from the dry case, as well as various large-scale instabilities of these nonequilibrium states of matter, are highlighted. Further highlighted are various large-scale instabilities of these nonequilibrium states of matter. Various semimicroscopic derivations of the continuum theory are discussed and connected, highlighting the unifying and generic nature of the continuum model. Throughout the review, the experimental relevance of these theories for describing bacterial swarms and suspensions, the cytoskeleton of living cells, and vibrated granular material is discussed. Promising extensions toward greater realism in specific contexts from cell biology to animal behavior are suggested, and remarks are given on some exotic active-matter analogs. Last, the outlook for a quantitative understanding of active matter, through the interplay of detailed theory with controlled experiments on simplified systems, with living or artificial constituents, is summarized. © 2013 American Physical Society.

Chatterjee S.,Indian Institute of Science | Padmanabhan B.,Indian Institute of Science
Chemical Reviews | Year: 2011

Structural chemistry of peptides containing backbone expanded amino acid residues is examined. For the present overview of folded conformations, simplified abbreviations for the substituted residues are used and defined at appropriate points in the text. The importance of hydrogen bonded rings in stabilizing the regular structures of fibrous proteins was first recognized by Maurice Huggins, whose major reviews in the early 1940s contain the fore-runners of many of the structures that have become commonplace today. The presence of gem dialkyl substituents on a carbon atom results in a restriction of the flanking torsional angles. Despite the many successes in characterizing folded structures in peptides containing backbone homologated amino acids, it must be recognized that even for conformationally constrained residues, several distinct regions of conformational space are energetically accessible.

Deshpande N.G.,University of Oregon | Garg S.K.,Indian Institute of Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We investigate e +e -→γγ process within the Seiberg-Witten expanded noncommutative standard model (NCSM) scenario in the presence of anomalous triple gauge boson couplings. This study is done with and without initial beam polarization and we restrict ourselves to leading order effects of noncommutativity i.e. O(Θ). The noncommutative (NC) corrections are sensitive to the electric component (Θ→E) of NC parameter. We include the effects of Earth's rotation in our analysis. This study is done by investigating the effects of noncommutativity on different time averaged cross section observables. We have also defined forward backward asymmetries which will be exclusively sensitive to anomalous couplings. We have looked into the sensitivity of these couplings at future experiments at the International Linear Collider (ILC). This analysis is done under realistic ILC conditions with the center of mass energy (c.m.) s=800 GeV and integrated luminosity L=500 fb -1. The scale of noncommutativity is assumed to be Λ=1 TeV. The limits on anomalous couplings of the order 10 -1 from forward backward asymmetries while much stringent limits of the order 10 -2 from total cross section are obtained if no signal beyond SM is seen. © 2012 Elsevier B.V..

Prasad D.,Indian Institute of Science | Sharma P.,Indian Institute of Science | Babul A.,University of Victoria
Astrophysical Journal | Year: 2015

Using high-resolution 3D and 2D (axisymmetric) hydrodynamic simulations in spherical geometry, we study the evolution of cool cluster cores heated by feedback-driven bipolar active galactic nuclei (AGNs) jets. Condensation of cold gas, and the consequent enhanced accretion, is required for AGN feedback to balance radiative cooling with reasonable efficiencies, and to match the observed cool core properties. A feedback efficiency (mechanical luminosity ≈ EMacc c2 where M acc is the mass accretion rate at 1 kpc) as small as 610-5 is sufficient to reduce the cooling/accretion rate by ∼ 10 compared to a pure cooling flow in clusters (with M200≲7x1014 M⊙). This value is much smaller compared to the ones considered earlier, and is consistent with the jet efficiency and the fact that only a small fraction of gas at 1 kpc is accreted onto the supermassive black hole (SMBH). The feedback efficiency in earlier works was so high that the cluster core reached equilibrium in a hot state without much precipitation, unlike what is observed in cool-core clusters. We find hysteresis cycles in all our simulations with cold mode feedback: condensation of cold gas when the ratio of the cooling-time to the free-fall time (tcool tff) is ≲10 leads to a sudden enhancement in the accretion rate; a large accretion rate causes strong jets and overheating of the hot intracluster medium such that tcool tff>10; further condensation of cold gas is suppressed and the accretion rate falls, leading to slow cooling of the core and condensation of cold gas, restarting the cycle. Therefore, there is a spread in core properties, such as the jet power, accretion rate, for the same value of core entropy or tcool tff. A smaller number of cycles is observed for higher efficiencies and for lower mass halos because the core is overheated to a longer cooling time. The 3D simulations show the formation of a few-kpc scale, rotationally supported, massive (∼1011M⊙) cold gas torus. Since the torus gas is not accreted onto the SMBH, it is largely decoupled from the feedback cycle. The radially dominant cold gas (T <5104K|vr|>vf) consists of fast cold gas uplifted by AGN jets and freely infalling cold gas condensing out of the core. The radially dominant cold gas extends out to 25 kpc for the fiducial run (halo mass 7x1014 M⊙ and feedback efficiency 6 10-5), with the average mass inflow rate dominating the outflow rate by a factor of≈2. We compare our simulation results with recent observations. © 2015. The American Astronomical Society. All rights reserved.

Surana P.,National Center for Biological science | Satchidanandam V.,Indian Institute of Science | Nair D.T.,National Center for Biological science
Nucleic Acids Research | Year: 2014

Flaviviral RNA-dependent RNA polymerases (RdRps) initiate replication of the single-stranded RNA genome in the absence of a primer. The template sequence 5′-CU-3′ at the 3′-end of the flaviviral genome is highly conserved. Surprisingly, flaviviral RdRps require high concentrations of the second incoming nucleotide GTP to catalyze de novo template-dependent RNA synthesis. We show that GTP stimulates de novo RNA synthesis by RdRp from Japanese encephalitis virus (jRdRp) also. Crystal structures of jRdRp complexed with GTP and ATP provide a basis for specific recognition of GTP. Comparison of the jRdRpGTP structure with other viral RdRp-GTP structures shows that GTP binds jRdRp in a novel conformation. Apo-jRdRp structure suggests that the conserved motif F of jRdRp occupies multiple conformations in absence of GTP. Motif F becomes ordered on GTP binding and occludes the nucleotide triphosphate entry tunnel. Mutational analysis of key residues that interact with GTP evinces that the jRdRpGTP structure represents a novel pre-initiation state. Also, binding studies show that GTP binding reduces affinity of RdRp for RNA, but the presence of the catalytic Mn2+ ion abolishes this inhibition. Collectively, these observations suggest that the observed pre-initiation state may serve as a checkpoint to prevent erroneous template-independent RNA synthesis by jRdRp during initiation. © 2013 The Author(s). Published by Oxford University Press.

Penmatsa A.,University of Oregon | Penmatsa A.,Indian Institute of Science | Wang K.H.,Amgen | Gouaux E.,Howard Hughes Medical Institute
Nature Structural and Molecular Biology | Year: 2015

Most antidepressants elicit their therapeutic benefits through selective blockade of Na + /Cl â -coupled neurotransmitter transporters. Here we report X-ray structures of the Drosophila melanogaster dopamine transporter in complexes with the polycyclic antidepressants nisoxetine or reboxetine. The inhibitors stabilize the transporter in an outward-open conformation by occupying the substrate-binding site. These structures explain how interactions between the binding pocket and substituents on the aromatic rings of antidepressants modulate drug-transporter selectivity. © 2015 Nature America, Inc. All rights reserved.

Patel K.M.,Indian Institute of Science | Sharma P.,University of Adelaide
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

The ATLAS and CMS experiments at the LHC have found significant excess in the diphoton invariant mass distribution near 750 GeV. We interpret this excess in a predictive nonsupersymmetric SU(5) grand unified framework with a singlet scalar and light adjoint fermions. The 750 GeV resonance is identified as a gauge singlet scalar. Both its production and decays are induced by 24 dimensional adjoint fermions predicted within SU(5). The adjoint fermions are assumed to be odd under Z2 symmetry which forbids their direct coupling to the standard model fermions. We show that the observed diphoton excess can be explained with sub-TeV adjoint fermions and with perturbative Yukawa coupling. A narrow width scenario is more preferred while a simultaneous explanation of observed cross section and large total decay width requires some of the adjoint fermions lighter than 375 GeV. The model also provides a singlet fermion as a candidate of cold dark matter. The gauge coupling unification is achieved in the framework by introducing color sextet scalars while being consistent with the proton decay constraint. © 2016 The Authors.

Agency: Cordis | Branch: FP7 | Program: CSA | Phase: ICT-2009.3.5 | Award Amount: 497.22K | Year: 2010

India and the European Union face common timely challenges in the very important and potential field of networked monitoring and control system technologies, which create a favorable environment for strategic collaboration. Consequently, the main aim of EUCLID is to increase co-operation in this field between Indian and European R&D specialists, ensuring mutual benefits.\nThe two-year project will start its analysis from industrial needs in 4 application domains - (1) transportation; (2) energy management; (3) industrial automation; (4) water supply / treatment. In parallel, industrial needs in the relevant application domains in Europe will be identified as well, and cross-mapped with the findings in India, paving way to further strengthen R&D collaboration.\nThe international Expert Group 10 high level specialists will work jointly with the consortium and will provide their expertise to project implementation and assistance to the development of long term EU-Indian monitoring and control collaborations.\nThe EUCLID project will map Indian monitoring and control competences, will compare them with the identified industrial needs both in India and in Europe and European research priorities, and will map potential collaboration opportunities. As a result, Catalogue of Indian R&D organisations will be prepared. The EUCLID project team will assess EU-India collaboration potential and will prepare an Opportunity Report and a roadmap for EU-Indian collaboration in the field of networked monitoring and control system technologies. The project plans to implement two awareness raising events, and a Delegation tour in India. It will aim to strengthen the industrial competitiveness in both India and the EU and to increase skills of R&D specialists. The mutual actions between EU and India will contribute to the inter-disciplinary excellence in control systems technologies.

Agency: Cordis | Branch: FP7 | Program: CSA-CA | Phase: NMP-2008-2.6-3 | Award Amount: 1.23M | Year: 2009

The stability of thin films in contact with different materials is a critical issue for a wide range of modern devices, including high-k films in the microelectronics industry, metal electrodes for fuel cells, and nanometer sized particles on oxides for catalysis. Some groups are working on thermodynamic analysis of thin film stability, who correlate relative interface energies with dopant adsorption. While this provides important thermodynamic parameters which can be used to evaluate the stability of thin films, information on the detailed atomistic structure and chemistry of the same interfaces needs to be correlated with the thermodynamic approach. Other groups use advanced characterization approaches to determine local atomistic structure and chemistry, and theoretical groups explore interface structure and energy through computational methods. It is the goal of this project to bridge between these working groups. This project will establish an environment to promote communication and collaboration between groups using thermodynamic approaches with groups studying the atomistic structure of interfaces, since bridging this particular scientific gap has the potential to result in new design criteria for advanced material systems. The project is based on a core group of European, and International partners, who have realized that such a form of communication is critical to advancing the field of interface science and interface based technology. The partners will establish structured programs for discussion via focused public workshops and summer schools, and via scientific exchange. While the core group of partners is academic, European industry will be involved in the structured discussions. The expected impact from this four-year project is methods to correlate between thermodynamic analyses of interfaces with atomistic structure. This will provide new approaches to understanding interface stability, adhesion and interface dependent functional properties.

Indian Institute of Science | Date: 2013-03-08

Embodiments of the disclosure relate to a low drop diode equivalent circuit. Piezoelectric device based vibration energy harvesting requires a rectifier for conversion of input ac to usable dc form. Power loss due to diode drop in rectifier is a significant fraction of the already low levels of harvested power. The low-drop-diode equivalent can replace the rectifier diodes and minimise power loss. The diode equivalent mimics a diode using linear region operated MOSFET. The diode equivalent is powered directly from input signal and requires no additional power supply for its control. Power used by the control circuit is kept at a value which gives an overall output power improvement. The diode equivalent replaces the four diodes in a full wave bridge rectifier, which is the basic full-wave rectifier and is a part of the more advanced rectifiers like switch-only and bias-flip rectifiers.

Agency: Cordis | Branch: FP7 | Program: CSA | Phase: INFRA-2009-3.3 | Award Amount: 1.23M | Year: 2010

EU-IndiaGrid2, capitalising on the achievements of the FP6 EU-IndiaGrid (EUIG1) project and huge developments in India on infrastructure and leveraging the expertise and experience obtained by its partners during EUIG1, will continue the momentum, attained in e-Infrastructures evolution in Europe and India, to create and ensure sustainable collaboration in many new areas of science, education and technology across the two regions.\nEU-IndiaGrid2 main objectives are to:\nO1)\tconsolidate & enhance cooperation between European and Indian e-Infrastructures for the benefit of EU-Indian collaboration in e-Science EU-IndiaGrid2 will make full use of the EUIG1 project achievements and of the strong cooperation links established with the foremost European and Indian e-Infrastructure initiatives paving the way for successful sustainable cooperation across European and Indian e-Infrastructures.\nO2)\tsupport a set of new grid applications in areas strategic for EU-Indian collaboration EU-IndiaGrid2 will support a set of applications in the domain of Climate Change, High energy Physics, Biology, Material Science which are considered strategic for EU-Indian collaboration in the ICT domain.\nO3)\tensure a sustainable approach to e-Infrastructures across Europe and India through dissemination actions, meetings & workshops EU-IndiaGrid2 will continue supporting the Roadmap for Sustainability outlined by the EUIG1 project relying on the progress towards objectives O1 and O2 and on targeted dissemination actions, meetings and events\nO4)\tfoster and enhance cooperation with other European Initiatives in the Asian region and worldwide EU-IndiaGrid2 will continue the strong cooperation links established by EUIG1 with the most relevant projects and institutions e.g. EGEE/EGI, GEANT and the major Indian e-Infrastructure Initiatives as GARUDA NGI and NKN. It will also cooperate with regional projects like EELA2, EuAsiaGrid, SEEGRID and, if approved the EUMEDSupport and EUChinaGrid2 proj

This invention relates to a method for detecting, (i) malignant astrocytoma from normal brain tissue (ii) glioblastoma and anaplastic astrocytoma (iii) primary glioblastoma and secondary glioblastoma (iv) progressive pathway and denovo pathway comprises determining the level of expression of miRNAs listed in table 2, 3, 4, 5, wherein a higher or lower level of expression of miRNAs in the test sample as compared to the control sample differentiates and kit for characterizing a) malignant astrocytoma from normal brain tissue cell comprising reagent capable of specifically detecting the level of expression of the genes of miRNAs and instructions for using said kit for characterizing malignant astrocyoma from normal brain tissue cells b) glioblastoma from anaplastic astrocytoma comprising reagent capable of specifically detecting the level of expression of the genes of miRNAs and instructions for using said kit for characterizing glioblastoma from anaplastic astrocyoma c) primary glioblastoma from secondary glioblastoma comprising reagent capable of specifically detecting the level of expression of the genes of miRNAs and instructions for using said kit for characterizing primary glioblastoma from secondary glioldastoma, d) progressive pathway from denovo pathway comprising reagent capable of specifically detecting the level of expression of the genes of miRNAs and instructions for using said kit for characterizing progressive pathway from denovo pathway.

Agency: Cordis | Branch: FP7 | Program: CSA | Phase: INFRA-2007-3.3;INFRA-2007-3.0-03 | Award Amount: 754.47K | Year: 2008

The EU and India have established an extensive Information Society dialogue. On the research side, six priority sectors were highlighted at the occasion of the last EU-India Information Society Forum: EUROINDIA 2006. Internet security, next generation mobile wireless, migration from IPv4 to IPv6, languages technologies, Open Source software and high capacity research and education network (e.g. possible connection of the European network GEANT to its Indian counterpart ERNET) are the main topics of such dialogue. ERNET, the educational and Research Network in India has deployed nationwide high speed networks to cover all universities and public research institutes. According to the new government policy, the broadband is of high priority along with IPv6 technology. With 6CHOICE Proposal, the close co-operation between ERNET and European GEANT and GRID network is planned. 6CHOICE project supports such co-operation through joint network interconnection, service planning and the experiments will be facilitated across ERNET and GEANT linked universities and research institutes. This will be complemented with number of workshops to be held and conducting workshops to different level of target audience and complemented with training events with experts involved. 6CHOICE will complement the implementation of the Framework Programme across Europe and India for future Community research and technological development policy activities including monitoring and assessment activities. In particular, the project will involve conferences, seminars, studies and analysis, working groups and expert groups, operational support and dissemination, information and communication activities, or a combination of these, as appropriate in each case. The activities proposed encourage and facilitate the participation of small research teams, newly developed and remote research centres in the activities of the Communication Network Development scheme.

Agency: Cordis | Branch: FP7 | Program: CP-SICA | Phase: HEALTH-2007-2.3.2-12 | Award Amount: 4.08M | Year: 2009

Malaria is a major public health problem in the developing world and is endemic in many regions of India. The development of novel strategies for malaria control requires a better understanding of the biology of malaria parasites. Our project aims at bringing a significant contribution to this field, through dissecting the signalling pathways that regulate essential processes in the life cycle of malaria parasites. The proposed research will merge two lines of investigation that have thus far been conducted largely independently from each other, namely: (i) the characterisation of components of signal transduction pathways (protein kinases, nucleotide cyclases, calcium signalling mediators) in malaria parasites; (ii) the study of specific biological processes during the life cycle of malaria parasites. Merging these two fields of malaria research will ensure a high level of complementarity and synergy within the consortium. Specific workpackages will be centred on understanding signalling-dependent regulation in the following processes and stage transition within the life cycle of malaria parasites: erythrocyte infection (invasion, parasite proliferation) sexual development (gametocytogenesis, gametogenesis, transmission to the mosquito vector) hepatocyte infection (invasion, parasite proliferation, egress) membrane dynamics (trafficking, transporters) Approaches will include proteomics, reverse genetics, structural biology, and the use of animal models of malaria. The consortium is constituted of EU and Indian partners with a proven track record either in research into one of the developmental stages/processes described above, or in signal transduction in malaria parasites. The project will significantly strenghten EU-India cooperation in this highly relevant topic.

News Article | March 16, 2016

A diverse team of global experts has been selected to lead ACS Omega, the American Chemical Society’s newest open access journal publishing peer-reviewed articles. Based in the Americas, Europe, India, and China, the editors not only represent key geographic regions of active R&D, they also bring expertise from four distinct scientific areas of interest. The new editors are Cornelia Bohne, a professor of chemistry at the University of Victoria in Canada; Krishna Ganesh, director of the Indian Institute of Science Education & Research in India; Luis Liz-Marzán, Ikerbasque research professor and scientific director at CIC biomaGUNE in Spain; and Deqing Zhang, director of the Institute of Chemistry, Chinese Academy of Sciences, in China. Bohne’s research focuses on developing the fundamental understanding of the dynamics of supramolecular systems and on the application of this knowledge to functional supramolecular materials. Ganesh is an expert in modified DNA and peptide-nucleic acids as novel cell-penetrating agents. As the first (founding and serving) director of IISER, Ganesh has built a unique, interdisciplinary infrastructure in which teaching and education are wholly integrated into state-of-the-art research. Liz-Marzán’s research focuses on nanoparticle synthesis and assembly, nanoplasmonics, and the development of nanoparticle-based sensing and diagnostic tools. He most recently served as a senior editor of the ACS journal Langmuir. Zhang’s research focuses on organic functional materials involving synthesis of organic functional molecules, spectroscopic studies, characterizations of self-assembly structures and optoelectronic properties, as well as applications for chemo/biosensing and imaging. “The ACS Omega editors have themselves authored in aggregate more than 850 peer-reviewed research articles, book chapters, and patents,” says Penelope Lewis, director of editorial and new product development in ACS Publications. “Their prolific publishing records and academic and professional achievements set the foundation for a team that will define and lead the editorial vision for the journal, drawing on a geographically diverse editorial board they will soon enlist—to be composed of active researchers with wide-ranging expertise and scientific backgrounds across chemistry, chemical engineering, and allied interdisciplinary scientific fields.” ACS Omega will begin accepting research submissions in April 2016 and will publish its first articles online early this summer.

News Article | March 7, 2016

When Max Born addressed the South Indian Science Association in November 1935, it was a time of great uncertainty in his life. The Nazi Party had already suspended the renowned quantum mechanics physicist's position at the University of Gottingen in 1933. He had been invited to teach at Cambridge, but it was temporary. Then, the Party terminated his tenure at Gottingen in the summer of 1935. Born took up an offer to work with C. V. Raman and his students for six months at the Indian Institute of Science in Bangalore. While there, he found that his family had lost its German citizenship rights. He was stateless and without a permanent home. And then, there was this uncertainty about two numbers. The scientific world had been coming to terms with two numbers that had emerged after a series of discoveries and theories in the previous four decades. They were unchanging and they had no units. One, the fine structure constant, defined the strength of interactions between fundamental particles and light. It is expressed as 1/137. The other, mu, related the mass of a proton to an electron. Born was after a unifying theory to relate all the fundamental forces of nature. He also wanted a theory that would explain where these constants came from. Something, he said, to “explain the existence of the heavy, and light elementary particles and their definite mass quotient 1840." It might seem a little bizarre that Born worried about a couple of constants. The sciences are full of constants—one defines the speed of light, another quantifies the pull of gravity, and so on. We routinely use these numbers, flipping to dog-eared tables in reference books, and coding them into our software without much thought because, well, they are constants. But the weird thing about such constants is that there is no theory to explain their existence. They are universal and they appear to be unchanging. So is the case with the masses of protons and electrons. But time and time again, they are validated through observation and experiment, not theory. What Born and so many others were after was a unifying theory that would demonstrate that there could only be one unchanging value for a constant. Without this theory, scientists resort to testing limits of a constant. Measuring the constant is a good way to verify that theories using them make sense, that science stands on firm ground. Error from the measurements can be a huge concern. So, instead of validating the masses of protons and electrons, it's useful to measure the ratio of their masses, a number that is free of the burden of units. The search for a unifying theory continued. Two years after Born's lecture, his Cambridge colleague, Paul Dirac, wondered in a Nature paper whether the constants were indeed constant if one were to look at the entire history of the cosmos. Measurements on earth are useful but it is a tiny blue dot in the vast universe. What Dirac asked decades ago is what physicists continue to ask today. Is it a constant everywhere in the universe? Why is it a constant? How constant? The question lingered even as the decades rolled on. “The most exact value at present for the ratio of proton to electron mass is 1836.12 +/-0.05,” wrote Friedrich Lenz in a 1951 Physical Review Letters paper. “It may be of interest to note that this number coincides with 6pi^5=1836.12.” That was the entire paper. Questioning the constant is really not that far fetched an idea: the existing theories don't prevent the constants from having a different value. The universe went through three broad phases – the initial radiation dominated phase soon after the Big Bang, a long matter dominated phase, and then a very long dark energy dominated phase that began six billion years ago. One hypothesis is that the mass ratio might have varied only in transitions between the phases. The actual value of the mass ratio (1836.15267389) is not of as much a concern as the uncertainty around its stature as a constant. And scientists have made incredible progress at tackling this uncertainty number. Later this year, researchers from the Vrije Universiteit in Amsterdam along with collaborators from the University of Amsterdam and the Swinburne University of Technology in Melbourne will publish an overview of their findings in the quarterly journal, Review of Modern Physics (the paper is available on arXiv). The mass ratio, they write, varies less than 0.0005 percent, not enough to call it a change. This is based on telescope observations going as far as 12.4 billion years back in time when the universe was only 10 percent of its current age. The conclusion is both mundane and astonishing. Change is so omnipresent that we don't think twice about how much it is part of our fabric. A human cell might endure a million DNA mutations within a day. Summer's green leaves become fall's orange before crackling as winter's brown under our feet, all within a year. Gases coalesced and gravitated around each other over millions of years, packing into rocks like our water-drenched earth that orbits the sun. But underneath all that change lies one number that connects them all and a number that has remain unchanged as far as we can see in the cosmos. And we don't know why. The mu is like scientific gospel that wills the universe into existence. The history of the cosmos is a good sandbox for measuring drifts in the constant. Since light from the early universe continues to reach earth, radio telescopes are effective tools to study the mass ratio. Ancient light interacts with gases in faraway galaxies and stars before reaching earth. The light arrives at earth with a fingerprint of these gases, which absorb certain frequencies of light. It shows up as absences in the spectrum when reviewing the telescope data. By comparing this fingerprint with lab measurements on the same gas, scientists can deduce the mass ratio variations. The Vrije Universiteit group is one of a handful of teams in the world that has been on the case of the proton-electron mass ratio for over a decade. They have collaborated with scientists from Australia, France, Russia, Switzerland, the U.S., the U.K., India and the Phillipines. They have probed tiny bits of hydrogen, ammonia and methanol hovering billions of years away in space. They have compared signals from the Very Large Telescope in the cold, dry desert of north Chile, from a 100-meter radio telescope in a historic spa town in Germany, and from a 30-meter radio telescope in the Spanish Sierra Nevada. They have even used the Hubble Space Telescope to look at white dwarf stars to see if environments with 10,000 times more gravity than earth would alter the mass ratio. And...nada. 'Null result' is one of the most common phrases in their papers. Which is good. Even a small change of a few percent in the value of the ratio would mean a different universe. A smaller mass ratio could mean a wimpier proton, and possibly a weaker pull for the electrons orbiting the nucleus, leading to different kind of matter. While the world isn't very kind to research that doesn't have anything new to offer, a null result doesn't mean the matter can be put to rest. Therein lies the quandry which makes the VU team's research feel like it is equal parts futile and important. No theory in physics can explain the constant mass ratio, the steadfast shepherd of science. It just is, *shrug*. Of course, the VU team is not alone in the search. As early as 1996, another team at the Ioffe Physical Technical Research Institute in Russia analyzed spectral lines from outer space to gauge variations in the mass ratio. Scientists at Cambridge and at the Swinburne University of Technology have looked for drifts in the fine structure constant. But it is the VU group that has perhaps been occupied with the mass ratio the most. Over more than a decade, this preoccupation has produced one of the most comprehensive and intriguing bodies of work. Year after year, across generations of graduate students and post-docs, they have published a paper that gently picks away at the question from different angles – a more distant spot in the universe, a different gravitational environment, a new tool to measure an old problem. The aim for future searches is to hunt further back in time and in different environments. Larger telescopes like the European Extremely Large Telescope will help in gathering fainter signals from the universe. And despite the vast measurements, many are in a very narrow slice of the sky. By broadening the field of view, scientists can probe data from other parts of the universe. The experimental search for a varying constant will likely continue as long as there is no theory to back its existence. A string of null results and small changes to the constant variability helps plug loopholes. As the authors of the Reviews of Modern Physics paper wrote, “Even incremental improvements setting boundaries on drifting fundamental constants are worthwhile to pursue, given the importance of this endeavor into the nature of physical law: Is it constant or not?” Each piece of cosmic doubt is up for scrutiny, to either be nullified in a future experiment or surface as evidence for the next investigator.

News Article | February 15, 2017

This book collates information from various literature to provide students with a unified guide to contemporary developments in atomic physics. In just 400 pages it largely succeeds in achieving this aim. The author is a professor of physics at the Indian Institute of Science in Bangalore. His research focuses on laser cooling and trapping of atoms, quantum optics, optical tweezers, quantum computation in ion traps, and tests of time-reversal symmetry using laser-cooled atoms. He received a PhD from the Massachusetts Institute of Technology under the supervision of David Pritchard, a leader in modern atomic physics and a mentor of two researchers – Eric Cornell and Wolfgang Ketterle – who went on to become Nobel laureates. The book addresses the basis of atomic physics and state-of-the-art topics. It explains material clearly, although the arrangement of information is quite different to classical atomic-physics textbooks. This is clearly motivated by the importance of certain topics in modern quantum-optics theory and experiments. The physics content is often accompanied by the history behind concepts and by explanations of why things are named the way they are. Historical notes and personal anecdotes give the book a very appealing flair. Chapter one covers different measurement systems and their merits, followed by universal units and fundamental constants, with a detailed explanation of which constants are truly fundamental. The next chapter is devoted to preliminary materials, starting with the harmonic oscillator and moving to concepts – namely coherent and squeezed states – that are important in quantum optics but not explicitly covered in some other books in the field. The chapter ends with a section on radiation, even including a description of the Casimir effect. Chapter three is called Atoms. Alongside classical content such as energy levels of one-electron atoms, interactions with magnetic and electric fields, and atoms in oscillating fields, this chapter explains dressed atoms and also, unfortunately only briefly, includes a description of the permanent atomic electric dipole moment (EDM). The following chapter is devoted to nuclear effects, the isotope shift and hyperfine structure. At this point it would have been nice to see some mention of the flourishing field of laser spectroscopy of radioactive nuclei, which exploits the two above effects to investigate the ground-state properties of nuclei far from the valley of stability. Chapter five is about resonance, which is often scattered around in other books about atomic physics. Here, interestingly, nuclear magnetic resonance (NMR) plays a central role, and the chapter connects this topic very naturally to atomic physics. The chapter closes with a description of the density matrix formalism. After this comes a chapter devoted to interactions, including the electric dipole approximation, selection rules, transition rates and spontaneous emission. The last section is concerned with differences in saturation intensities by broadband and monochromatic radiation. Multiphoton interactions are the topic of chapter seven, which is clearly motivated by their importance in modern quantum-optics laboratories. Two-photon absorption and de-excitation, Raman processes and the dressed atom description are all explained. Another crucial concept in modern quantum optics is coherence. Thus it is included as a full chapter, which includes coherence in a single atom and in ensembles of atoms, as well as coherent control in multilevel atoms. Spin echo appears as well, showing again how close the topics presented in the book are to NMR. Chapter nine is devoted to lineshapes, which is clearly a subject relevant for modern atomic spectroscopists. Spectroscopy is the next chapter, which starts with alkali atoms – used extensively in laser cooling and Bose–Einstein condensates. The rest of the material is aimed at experimentalists. Uniquely for such a book, it includes a description of the key experimental tools, followed by Doppler-free techniques and nonlinear magneto-optic rotation. The last chapter covers cooling and trapping, with so many relevant concepts already presented in the preceding chapters. The content includes different cooling approaches, principles of atom and ion traps, the cryptic and equally common Zeeman slower, and even more intriguing optical tweezers. Each chapter ends with a problems section, in which the problems are often relevant to a real quantum-optics lab, for example concerning quantum defects, RF-induced magnetic transitions, Raman scattering cross-sections, quantum beats or the Voigt line profile. The problems are worked out in detail, allowing readers to follow how to arrive at the solution. The appendices cover the standards and the frequency comb, which is one of the ingenious devices to come from the laboratory of Nobel laureate Theodor Hänsch and which can be now found in an ever-growing number of laser-spectroscopy and quantum-optics labs. Two other appendices are very different: they have a philosophical flair and deal with the nature of the photon and with Einstein as nature’s detective. The presented theoretical basis leads to state-of-the art experiments, especially related to ion and atom cooling and to Bose–Einstein condensates. The selection of topics is thus clearly tailored for experimentalists working in a quantum optics lab. One small criticism is that it would be good to read more about the EDM experiments and laser spectroscopy of radioactive ions, which are currently two very active fields. Readers interested in different classic subjects, like atomic collisions, should turn to other books such as Bransden and Joachain’s Physics of Atoms and Molecules. The level of the book makes it suitable for undergraduate level, but also for new graduate students. It can also serve as a quick reference for researchers, especially concerning the topics of general interest: metrology, what is a photon or how a frequency comb works, and how to achieve a Bose–Einstein condensate. Overall, the book is a very good guide to the topics relevant in modern atomic physics and its style makes it quite unique and personal. Probability for Physicists By Simon Širca Springer Also available at the CERN bookshop This book aims to deliver a concise, practical and intuitive introduction to probability and statistics for undergraduate and graduate students of physics and other natural sciences. The author attempts to provide a textbook in which mathematical complexity is reduced to a minimum, yet without sacrificing precision and clarity. To increase the appeal of the book for students, classic dice-throwing and coin-tossing examples are replaced or accompanied by real physics problems, all of which come with full solutions. In the first part (chapters 1–6), the basics of probability and distributions are discussed. A second block of chapters is dedicated to statistics, specifically the determination of distribution parameters based on samples. More advanced topics follow, including Markov processes, the Monte Carlo method, stochastic population modelling, entropy and information. The author also chooses to cover some subjects that, according to him, are disappearing from modern statistics courses. These include extreme-value distributions, the maximum-likelihood method and linear regressions using singular-value decomposition. A set of appendices concludes the volume. Introduction to Quantum Physics and Information Processing By Radhika Vathsan CRC Press An introduction to the novel and developing field of quantum information, this book aims to provide undergraduate and beginning graduate students with all of the basic concepts needed to understand more advanced books and current research publications in the field. No background in quantum physics is required because its essential principles are provided in the first part of the book. After an introduction to the methods and notation of quantum mechanics, the authors explain a typical two-state system and how it is used to describe quantum information. The broader theoretical framework is also set out, starting with the rules of quantum mechanics and the language of algebra. The book proceeds by showing how quantum properties are exploited to develop algorithms that prove more efficient in solving specific problems than their classical counterparts. Quantum computation, information content in qubits, cryptographic applications of quantum-information processing and quantum-error correction are some of the key topics covered in this book. In addition to the many examples developed in the text, exercises are provided at the end of each chapter. References to more advanced material are also included. Position-Sensitive Gaseous Photomultipliers: Research and Applications By Tom Francke and Vladimir Peskov IGI Global Gaseous photomultipliers are gas-filled devices capable of detecting single photons (in the visible and UV spectrum) with a high position resolution. They are used in various research settings, in particular high-energy physics, and are among several types of contemporary single-photon detectors. This book provides a detailed comparison between photosensitive detectors based on different technologies, highlighting their advantages and disadvantages of them for diverse applications. After describing the main principles underlying the conversion of photons to photoelectrons and the electron avalanche multiplication effect, the characteristics (and requirements) of position-sensitive gaseous photomultipliers are discussed. A long section of the book is then dedicated to describing and analysing the development of these detectors, which evolved from photomultipliers filled with photosensitive vapours to devices using liquid and then solid photocathodes. UV-sensitive photodetectors based on caesium iodide and caesium telluride, which are mainly used as Cherenkov-ring imaging detectors and are currently employed in the ALICE and COMPASS experiments at CERN, are presented in a dedicated chapter. The latest generation of gaseous photomultipliers, sensitive up to the visible region, are also discussed, as are alternative position-sensitive detectors. The authors then focus on the Cherenkov light effect, its discovery and the way it has been used to identify particles. The introduction of ring imaging Cherenkov (RICH) detectors was a breakthrough and led to the application of these devices in various experiments, including the Cosmic AntiParticle Ring Imaging Cherenkov Experiment (CAPRICE) and the former CERN experiment Charge Parity violation at Low Energy Antiproton Ring (CP LEAR). The latest generation of RICH detectors and applications of gaseous photomultipliers beyond RICH detectors are also discussed, completing the overview of the subject. 17 Big Bets for a Better World By S Tackmann, K Kampmann and H Skovby (eds) Forlaget Historika/Gad Publishers This book, which includes a contribution by CERN Director-General Fabiola Gianotti, presents 17 radical and game-changing ideas to help reach the 2030 Global Goals for Sustainable Development identified by the United Nations General Assembly. Renowned and influential leaders propose innovative solutions for 17 “big bets” that the human race must face in the coming years. These experts in the environment, finance, food security, education and other relevant disciplines share their vision of the future and suggest new paths towards sustainability. In the book, Gianotti replies to this call and shares her ideas about the importance of basic science and research in science, technology, engineering and maths (STEM) to underpin innovation, sustainable development and the improvement of global living conditions. After giving examples of breakthrough innovations in technology and medicine that came about from the pursuit of knowledge for its own sake, Gianotti contends that we need science and scientifically aware citizens to be able to tackle pressing issues, including drastic reduction of poverty and hunger, and the provision of clean and affordable energy. Finally, she proposes a plan to secure STEM education and funding for basic scientific research. Published as part of the broader Big Bet Initiative to engage stakeholders around new and innovative ideas for global development, this book provides fresh points of view and credible solutions. It would appeal to readers who are interested in innovation and sustainability, as well as in the role of science in such a framework.

Degottardi W.,University of Illinois at Urbana - Champaign | Sen D.,Indian Institute of Science | Vishveshwara S.,University of Illinois at Urbana - Champaign
Physical Review Letters | Year: 2013

We present a unified study of the effect of periodic, quasiperiodic, and disordered potentials on topological phases that are characterized by Majorana end modes in one-dimensional p-wave superconducting systems. We define a topological invariant derived from the equations of motion for Majorana modes and, as our first application, employ it to characterize the phase diagram for simple periodic structures. Our general result is a relation between the topological invariant and the normal state localization length. This link allows us to leverage the considerable literature on localization physics and obtain the topological phase diagrams and their salient features for quasiperiodic and disordered systems for the entire region of parameter space. © 2013 American Physical Society.

Djouadi A.,University Paris - Sud | Godbole R.M.,Indian Institute of Science | Mellado B.,University of Wisconsin - Madison | Mellado B.,University of Witwatersrand | Mohan K.,Indian Institute of Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

Determining the spin and the parity quantum numbers of the recently discovered Higgs-like boson at the LHC is a matter of great importance. In this Letter, we consider the possibility of using the kinematics of the tagging jets in Higgs production via the vector boson fusion (VBF) process to test the tensor structure of the Higgs-vector boson (HVV) interaction and to determine the spin and CP properties of the observed resonance. We show that an anomalous HVV vertex, in particular its explicit momentum dependence, drastically affects the rapidity between the two scattered quarks and their transverse momenta and, hence, the acceptance of the kinematical cuts that allow to select the VBF topology. The sensitivity of these observables to different spin-parity assignments, including the dependence on the LHC center of mass energy, are evaluated. In addition, we show that in associated Higgs production with a vector boson some kinematical variables, such as the invariant mass of the system and the transverse momenta of the two bosons and their separation in rapidity, are also sensitive to the spin-parity assignments of the Higgs-like boson. © 2013 Elsevier B.V.

DeGottardi W.,University of Illinois at Urbana - Champaign | Sen D.,Indian Institute of Science | Vishveshwara S.,University of Illinois at Urbana - Champaign
New Journal of Physics | Year: 2011

We explore the salient features of the 'Kitaev ladder', a two-legged ladder version of the spin-1/2 Kitaev model on a honeycomb lattice, by mapping it to a one-dimensional fermionic p-wave superconducting system. We examine the connections between spin phases and topologically non-trivial phases of non-interacting fermionic systems, demonstrating the equivalence between the spontaneous breaking of global Z2 symmetry in spin systems and the existence of isolated Majorana modes. In the Kitaev ladder, we investigate topological properties of the system in different sectors characterized by the presence or absence of a vortex in each plaquette of the ladder. We show that vortex patterns can yield a rich parameter space for tuning into topologically non-trivial phases. We introduce and employ a new topological invariant for explicitly determining the presence of zero energy Majorana modes at the boundaries of such phases. Finally, we discuss dynamic quenching between topologically non-trivial phases in the Kitaev ladder and, in particular, the post-quench dynamics governed by tuning through a quantum critical point. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Atodiresei N.,Jülich Research Center | Raman K.V.,Indian Institute of Science
MRS Bulletin | Year: 2014

Organic molecules adsorbed on magnetic surfaces offer the possibility to merge the concepts of molecular electronics with spintronics to build future nanoscale data storage, sensing, and computing multifunctional devices. In order to engineer the functionalities of such hybrid spintronic devices, an understanding of the electronic and magnetic properties of the interface between carbon-based aromatic materials and magnetic surfaces is essential. In this article, we discuss recent progress in the study of spin-dependent chemistry and physics associated with the above molecule-ferromagnet interface by combining state-of-the-art experiments and theoretical calculations. The magnetic properties such as molecular magnetic moment, electronic interface spin-polarization, magnetic anisotropy, and magnetic exchange coupling can be specifically tuned by an appropriate choice of the organic material and the magnetic substrate. These reports suggest a gradual shift in research toward an emerging subfield of interface-assisted molecular spintronics. © Materials Research Society 2014.

Manna D.,Indian Institute of Science | Roy G.,Shiv Nadar University | Mugesh G.,Indian Institute of Science
Accounts of Chemical Research | Year: 2013

Thyroid hormones are essential for the development and differentiation of all cells of the human body. They regulate protein, fat, and carbohydrate metabolism. In this Account, we discuss the synthesis, structure, and mechanism of action of thyroid hormones and their analogues.The prohormone thyroxine (T4) is synthesized on thyroglobulin by thyroid peroxidase (TPO), a heme enzyme that uses iodide and hydrogen peroxide to perform iodination and phenolic coupling reactions. The monodeiodination of T4 to 3,3′,5-triiodothyronine (T3) by selenium-containing deiodinases (ID-1, ID-2) is a key step in the activation of thyroid hormones. The type 3 deiodinase (ID-3) catalyzes the deactivation of thyroid hormone in a process that removes iodine selectively from the tyrosyl ring of T4 to produce 3,3′,5′-triiodothyronine (rT3). Several physiological and pathological stimuli influence thyroid hormone synthesis. The overproduction of thyroid hormones leads to hyperthyroidism, which is treated by antithyroid drugs that either inhibit the thyroid hormone biosynthesis and/or decrease the conversion of T4 to T3.Antithyroid drugs are thiourea-based compounds, which include propylthiouracil (PTU), methimazole (MMI), and carbimazole (CBZ). The thyroid gland actively concentrates these heterocyclic compounds against a concentration gradient. Recently, the selenium analogues of PTU, MMI, and CBZ attracted significant attention because the selenium moiety in these compounds has a higher nucleophilicity than that of the sulfur moiety. Researchers have developed new methods for the synthesis of the selenium compounds. Several experimental and theoretical investigations revealed that the selone (Cî-Se) in the selenium analogues is more polarized than the thione (Cî-S) in the sulfur compounds, and the selones exist predominantly in their zwitterionic forms.Although the thionamide-based antithyroid drugs have been used for almost 70 years, the mechanism of their action is not completely understood. Most investigations have revealed that MMI and PTU irreversibly inhibit TPO. PTU, MTU, and their selenium analogues also inhibit ID-1, most likely by reacting with the selenenyl iodide intermediate. The good ID-1 inhibitory activity of PTU and its analogues can be ascribed to the presence of the -N(H)-C(î-O)- functionality that can form hydrogen bonds with nearby amino acid residues in the selenenyl sulfide state. In addition to the TPO and ID-1 inhibition, the selenium analogues are very good antioxidants. In the presence of cellular reducing agents such as GSH, these compounds catalytically reduce hydrogen peroxide. They can also efficiently scavenge peroxynitrite, a potent biological oxidant and nitrating agent. © 2013 American Chemical Society.

Santra P.K.,University of Notre Dame | Nair P.V.,University of Notre Dame | Nair P.V.,Indian Institute of Science | George Thomas K.,Indian Institute of Science | Kamat P.V.,University of Notre Dame
Journal of Physical Chemistry Letters | Year: 2013

Ternary metal chalcogenides such as CuInS2 offer new opportunities to design quantum dot solar cells (QDSC). Chemically synthesized CuInS2 quantum dots (particle diameter, 2.6 nm) have been successfully deposited within the mesoscopic TiO2 film using electrophoretic deposition (150 V cm-1 dc field). The primary photoinduced process of electron injection from excited CuInS2 into TiO2 occurs with a rate constant of 5.75 × 1011 s-1. The TiO2/CuInS2 films are photoactive and produce anodic photocurrent with a power conversion efficiency of 1.14%. Capping the TiO2/CuInS2 film with a CdS layer decreases the interfacial charge recombination and thus offers further improvement in the power conversion efficiency (3.91%). The synergy of using CdS as a passivation layer in the composite film is also evident from the increased external quantum efficiency of the electrode in the red region where only CuInS2 absorbs the incident light. © 2013 American Chemical Society.

Agency: Cordis | Branch: FP7 | Program: CP-IP | Phase: HEALTH.2010.2.3.2-1 | Award Amount: 16.70M | Year: 2011

The More Medicines for Tuberculosis (MM4TB) consortium evolved from the highly successful FP6 project, New Medicines for TB (NM4TB), that delivered a candidate drug for clinical development two years ahead of schedule. Building on these firm foundations and exploiting its proprietary pharmacophores, MM4TB will continue to develop new drugs for TB treatment. An integrated approach will be implemented by a multidisciplinary team that combines some of Europes leading academic TB researchers with two major pharmaceutical companies and four SMEs, all strongly committed to the discovery of anti-infective agents. MM4TB will use a tripartite screening strategy to discover new hits in libraries of natural products and synthetic compounds, while concentrating on both classical and innovative targets that have been pharmacologically validated. Whole cell screens will be conducted against Mycobacterium tuberculosis using in vitro and ex vivo models for active growth, latency and intracellular infection. Hits that are positive in two or more of these models will then be used for target identification using functional genomics technologies including whole genome sequencing and genetic complementation of resistant mutants, yeast three hybrid, click chemistry and proteomics. Targets thus selected will enter assay development, structure determination, fragment-based and rational drug design programs; functionally related targets will be found using metabolic pathway reconstruction. Innovative techniques, based on microfluidics and array platforms, will be used for hit ranking, determining rates of cidality and confirming mechanism of action. Medicinal chemistry will convert leads to molecules with drug-like properties for evaluation of efficacy in different animal models and late preclinical testing.

News Article | December 22, 2016

Building nanomaterials with features spanning just billionths of a meter requires extraordinary precision. Scaling up that construction while increasing complexity presents a significant hurdle to the widespread use of such nano-engineered materials. Now, scientists at the U.S. Department of Energy's Brookhaven National Laboratory have developed a way to efficiently create scalable, multilayer, multi-patterned nanoscale structures with unprecedented complexity. The Brookhaven team exploited self-assembly, where materials spontaneous snap together to form the desired structure. But they introduced a significant leap in material intelligence, because each self-assembled layer now guides the configuration of additional layers. The results, published in the journal Nature Communications, offer a new paradigm for nanoscale self-assembly, potentially advancing nanotechnology used for medicine, energy generation, and other applications. "There's something amazing and rewarding about creating structures no one has ever seen before," says study coauthor Kevin Yager, a scientist at Brookhaven Lab's Center for Functional Nanomaterials (CFN). "We're calling this responsive layering — like building a tower, but where each brick is intelligent and contains instructions for subsequent bricks." The technique was pioneered entirely at the CFN, a DOE Office of Science User Facility. "The trick was chemically 'sealing' each layer to make it robust enough that the additional layers don't disrupt it," says lead author Atikur Rahman, a Brookhaven Lab postdoc during the study and now an assistant professor at the Indian Institute of Science Education and Research, Pune. "This granted us unprecedented control. We can now stack any sequence of self-organized layers to create increasingly intricate 3D structures." Other nano-fabrication methods — such as lithography — can create precise nano-structures, but the spontaneous ordering of self-assembly makes it faster and easier. Further, responsive layering pushes that efficiency in new directions, enabling, for example, structures with internal channels or pockets that would be exceedingly difficult to make by any other means. "Self-assembly is inexpensive and scalable because it's driven by intrinsic interactions," says study coauthor and CFN scientist Gregory Doerk. "We avoid the complex tools that are traditionally used to carve precise nano-structures." The CFN collaboration used thin films of block copolymers (BCP) — chains of two distinct molecules linked together. Through well-established techniques, the scientists spread BCP films across a substrate, applied heat, and watched the material self-assemble into a prescribed configuration. Imagine spreading LEGOs over a baking sheet, sticking it in the oven, and then seeing it emerge with each piece elegantly snapped together in perfect order. However, these materials are conventionally two-dimensional, and simply stacking them would yield a disordered mess. So the Brookhaven Lab scientists developed a way to have self-assembled layers discretely "talk" to one another. The team infused each layer with a vapor of inorganic molecules to seal the structure — a bit like applying nanoscale shellac to preserve a just-assembled puzzle. "We tuned the vapor infiltration step so that each layer's structure exhibits controlled surface contours," Rahman says. "Subsequent layers then feel and respond to this subtle topography." Coauthor Pawel Majewski adds, "Essentially, we open up a 'conversation' between layers. The surface patterns drive a kind of topographic crosstalk, and each layer acts as a template for the next one." As often occurs in fundamental research, this crosstalk was an unexpected phenomenon. "We were amazed when we first saw templated ordering from one layer to the next, Rahman says. "We knew immediately that we had to exhaustively test all the possible combinations of film layers and explore the technique's potential." The collaboration demonstrated the formation of a broad range of nano-structures — including many configurations never before observed. Some contained hollow chambers, round pegs, rods, and winding shapes. "This was really a Herculean effort on the part of Atikur," Yager says. "The multi-layer samples covered a staggering range of combinations." The scientists used scanning electron microscopy (SEM) to probe the nanoscale features, getting cross-sectional details of the emergent structures. A focused electron beam bombarded the sample, bouncing off surface features before being detected to enable reconstruction of an image depicting the exact configuration. They complemented this with x-ray scattering at Brookhaven's National Synchrotron Light Source II — another DOE Office of Science User Facility. The penetrative scattering technique allowed the researchers to probe the internal structure. "CFN brings together a unique concentration of skills, interests, and technology," says CFN Director and coauthor Charles Black. "In one facility, we have people interested in creating, converting, and measuring structures — that's how we can have these kinds of unanticipated and highly collaborative breakthroughs." This fundamental breakthrough substantially broadens the diversity and complexity of structures that can be made with self-assembly, and correspondingly broadens the range of potential applications. For example, intricate three-dimensional nanostructures could yield transformative improvements in nano-porous membranes for water purification, bio-sensing, or catalysis. This work was supported by the DOE Office of Science.

News Article | December 22, 2016

Now, scientists at the U.S. Department of Energy's Brookhaven National Laboratory have developed a way to efficiently create scalable, multilayer, multi-patterned nanoscale structures with unprecedented complexity. The Brookhaven team exploited self-assembly, where materials spontaneous snap together to form the desired structure. But they introduced a significant leap in material intelligence, because each self-assembled layer now guides the configuration of additional layers. The results, published in the journal Nature Communications, offer a new paradigm for nanoscale self-assembly, potentially advancing nanotechnology used for medicine, energy generation, and other applications. "There's something amazing and rewarding about creating structures no one has ever seen before," said study coauthor Kevin Yager, a scientist at Brookhaven Lab's Center for Functional Nanomaterials (CFN). "We're calling this responsive layering-like building a tower, but where each brick is intelligent and contains instructions for subsequent bricks." The technique was pioneered entirely at the CFN, a DOE Office of Science User Facility. "The trick was chemically 'sealing' each layer to make it robust enough that the additional layers don't disrupt it," said lead author Atikur Rahman, a Brookhaven Lab postdoc during the study and now an assistant professor at the Indian Institute of Science Education and Research, Pune. "This granted us unprecedented control. We can now stack any sequence of self-organized layers to create increasingly intricate 3D structures." Other nano-fabrication methods-such as lithography-can create precise nano-structures, but the spontaneous ordering of self-assembly makes it faster and easier. Further, responsive layering pushes that efficiency in new directions, enabling, for example, structures with internal channels or pockets that would be exceedingly difficult to make by any other means. "Self-assembly is inexpensive and scalable because it's driven by intrinsic interactions," said study coauthor and CFN scientist Gregory Doerk. "We avoid the complex tools that are traditionally used to carve precise nano-structures." The CFN collaboration used thin films of block copolymers (BCP)-chains of two distinct molecules linked together. Through well-established techniques, the scientists spread BCP films across a substrate, applied heat, and watched the material self-assemble into a prescribed configuration. Imagine spreading LEGOs over a baking sheet, sticking it in the oven, and then seeing it emerge with each piece elegantly snapped together in perfect order. However, these materials are conventionally two-dimensional, and simply stacking them would yield a disordered mess. So the Brookhaven Lab scientists developed a way to have self-assembled layers discretely "talk" to one another. The team infused each layer with a vapor of inorganic molecules to seal the structure-a bit like applying nanoscale shellac to preserve a just-assembled puzzle. "We tuned the vapor infiltration step so that each layer's structure exhibits controlled surface contours," Rahman said. "Subsequent layers then feel and respond to this subtle topography." Coauthor Pawel Majewski added, "Essentially, we open up a 'conversation' between layers. The surface patterns drive a kind of topographic crosstalk, and each layer acts as a template for the next one." As often occurs in fundamental research, this crosstalk was an unexpected phenomenon. "We were amazed when we first saw templated ordering from one layer to the next, Rahman said. "We knew immediately that we had to exhaustively test all the possible combinations of film layers and explore the technique's potential." The collaboration demonstrated the formation of a broad range of nano-structures-including many configurations never before observed. Some contained hollow chambers, round pegs, rods, and winding shapes. "This was really a Herculean effort on the part of Atikur," Yager said. "The multi-layer samples covered a staggering range of combinations." The scientists used scanning electron microscopy (SEM) to probe the nanoscale features, getting cross-sectional details of the emergent structures. A focused electron beam bombarded the sample, bouncing off surface features before being detected to enable reconstruction of an image depicting the exact configuration. They complemented this with x-ray scattering at Brookhaven's National Synchrotron Light Source II-another DOE Office of Science User Facility. The penetrative scattering technique allowed the researchers to probe the internal structure. "CFN brings together a unique concentration of skills, interests, and technology," said CFN Director and coauthor Charles Black. "In one facility, we have people interested in creating, converting, and measuring structures-that's how we can have these kinds of unanticipated and highly collaborative breakthroughs." This fundamental breakthrough substantially broadens the diversity and complexity of structures that can be made with self-assembly, and correspondingly broadens the range of potential applications. For example, intricate three-dimensional nanostructures could yield transformative improvements in nano-porous membranes for water purification, bio-sensing, or catalysis. Explore further: Smarter self-assembly opens new pathways for nanotechnology

Home > Press > Nanoscale 'conversations' create complex, multi-layered structures: New technique leverages controlled interactions across surfaces to create self-assembled materials with unprecedented complexity Abstract: Building nanomaterials with features spanning just billionths of a meter requires extraordinary precision. Scaling up that construction while increasing complexity presents a significant hurdle to the widespread use of such nano-engineered materials. Now, scientists at the U.S. Department of Energy's Brookhaven National Laboratory have developed a way to efficiently create scalable, multilayer, multi-patterned nanoscale structures with unprecedented complexity. The Brookhaven team exploited self-assembly, where materials spontaneous snap together to form the desired structure. But they introduced a significant leap in material intelligence, because each self-assembled layer now guides the configuration of additional layers. The results, published in the journal Nature Communications, offer a new paradigm for nanoscale self-assembly, potentially advancing nanotechnology used for medicine, energy generation, and other applications. "There's something amazing and rewarding about creating structures no one has ever seen before," said study coauthor Kevin Yager, a scientist at Brookhaven Lab's Center for Functional Nanomaterials (CFN). "We're calling this responsive layering-like building a tower, but where each brick is intelligent and contains instructions for subsequent bricks." The technique was pioneered entirely at the CFN, a DOE Office of Science User Facility. "The trick was chemically 'sealing' each layer to make it robust enough that the additional layers don't disrupt it," said lead author Atikur Rahman, a Brookhaven Lab postdoc during the study and now an assistant professor at the Indian Institute of Science Education and Research, Pune. "This granted us unprecedented control. We can now stack any sequence of self-organized layers to create increasingly intricate 3D structures." Guiding nanoscale conversations Other nano-fabrication methods-such as lithography-can create precise nano-structures, but the spontaneous ordering of self-assembly makes it faster and easier. Further, responsive layering pushes that efficiency in new directions, enabling, for example, structures with internal channels or pockets that would be exceedingly difficult to make by any other means. "Self-assembly is inexpensive and scalable because it's driven by intrinsic interactions," said study coauthor and CFN scientist Gregory Doerk. "We avoid the complex tools that are traditionally used to carve precise nano-structures." The CFN collaboration used thin films of block copolymers (BCP)-chains of two distinct molecules linked together. Through well-established techniques, the scientists spread BCP films across a substrate, applied heat, and watched the material self-assemble into a prescribed configuration. Imagine spreading LEGOs over a baking sheet, sticking it in the oven, and then seeing it emerge with each piece elegantly snapped together in perfect order. However, these materials are conventionally two-dimensional, and simply stacking them would yield a disordered mess. So the Brookhaven Lab scientists developed a way to have self-assembled layers discretely "talk" to one another. The team infused each layer with a vapor of inorganic molecules to seal the structure-a bit like applying nanoscale shellac to preserve a just-assembled puzzle. "We tuned the vapor infiltration step so that each layer's structure exhibits controlled surface contours," Rahman said. "Subsequent layers then feel and respond to this subtle topography." Coauthor Pawel Majewski added, "Essentially, we open up a 'conversation' between layers. The surface patterns drive a kind of topographic crosstalk, and each layer acts as a template for the next one." Exotic configurations As often occurs in fundamental research, this crosstalk was an unexpected phenomenon. "We were amazed when we first saw templated ordering from one layer to the next, Rahman said. "We knew immediately that we had to exhaustively test all the possible combinations of film layers and explore the technique's potential." The collaboration demonstrated the formation of a broad range of nano-structures-including many configurations never before observed. Some contained hollow chambers, round pegs, rods, and winding shapes. "This was really a Herculean effort on the part of Atikur," Yager said. "The multi-layer samples covered a staggering range of combinations." Mapping never-before-seen structures The scientists used scanning electron microscopy (SEM) to probe the nanoscale features, getting cross-sectional details of the emergent structures. A focused electron beam bombarded the sample, bouncing off surface features before being detected to enable reconstruction of an image depicting the exact configuration. They complemented this with x-ray scattering at Brookhaven's National Synchrotron Light Source II-another DOE Office of Science User Facility. The penetrative scattering technique allowed the researchers to probe the internal structure. "CFN brings together a unique concentration of skills, interests, and technology," said CFN Director and coauthor Charles Black. "In one facility, we have people interested in creating, converting, and measuring structures-that's how we can have these kinds of unanticipated and highly collaborative breakthroughs." This fundamental breakthrough substantially broadens the diversity and complexity of structures that can be made with self-assembly, and correspondingly broadens the range of potential applications. For example, intricate three-dimensional nanostructures could yield transformative improvements in nano-porous membranes for water purification, bio-sensing, or catalysis. ### This work was supported by the DOE Office of Science. About Brookhaven National Laboratory Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

News Article | December 22, 2016

UPTON, NY -- Building nanomaterials with features spanning just billionths of a meter requires extraordinary precision. Scaling up that construction while increasing complexity presents a significant hurdle to the widespread use of such nano-engineered materials. Now, scientists at the U.S. Department of Energy's Brookhaven National Laboratory have developed a way to efficiently create scalable, multilayer, multi-patterned nanoscale structures with unprecedented complexity. The Brookhaven team exploited self-assembly, where materials spontaneous snap together to form the desired structure. But they introduced a significant leap in material intelligence, because each self-assembled layer now guides the configuration of additional layers. The results, published in the journal Nature Communications, offer a new paradigm for nanoscale self-assembly, potentially advancing nanotechnology used for medicine, energy generation, and other applications. "There's something amazing and rewarding about creating structures no one has ever seen before," said study coauthor Kevin Yager, a scientist at Brookhaven Lab's Center for Functional Nanomaterials (CFN). "We're calling this responsive layering-like building a tower, but where each brick is intelligent and contains instructions for subsequent bricks." The technique was pioneered entirely at the CFN, a DOE Office of Science User Facility. "The trick was chemically 'sealing' each layer to make it robust enough that the additional layers don't disrupt it," said lead author Atikur Rahman, a Brookhaven Lab postdoc during the study and now an assistant professor at the Indian Institute of Science Education and Research, Pune. "This granted us unprecedented control. We can now stack any sequence of self-organized layers to create increasingly intricate 3D structures." Other nano-fabrication methods-such as lithography-can create precise nano-structures, but the spontaneous ordering of self-assembly makes it faster and easier. Further, responsive layering pushes that efficiency in new directions, enabling, for example, structures with internal channels or pockets that would be exceedingly difficult to make by any other means. "Self-assembly is inexpensive and scalable because it's driven by intrinsic interactions," said study coauthor and CFN scientist Gregory Doerk. "We avoid the complex tools that are traditionally used to carve precise nano-structures." The CFN collaboration used thin films of block copolymers (BCP)-chains of two distinct molecules linked together. Through well-established techniques, the scientists spread BCP films across a substrate, applied heat, and watched the material self-assemble into a prescribed configuration. Imagine spreading LEGOs over a baking sheet, sticking it in the oven, and then seeing it emerge with each piece elegantly snapped together in perfect order. However, these materials are conventionally two-dimensional, and simply stacking them would yield a disordered mess. So the Brookhaven Lab scientists developed a way to have self-assembled layers discretely "talk" to one another. The team infused each layer with a vapor of inorganic molecules to seal the structure-a bit like applying nanoscale shellac to preserve a just-assembled puzzle. "We tuned the vapor infiltration step so that each layer's structure exhibits controlled surface contours," Rahman said. "Subsequent layers then feel and respond to this subtle topography." Coauthor Pawel Majewski added, "Essentially, we open up a 'conversation' between layers. The surface patterns drive a kind of topographic crosstalk, and each layer acts as a template for the next one." As often occurs in fundamental research, this crosstalk was an unexpected phenomenon. "We were amazed when we first saw templated ordering from one layer to the next, Rahman said. "We knew immediately that we had to exhaustively test all the possible combinations of film layers and explore the technique's potential." The collaboration demonstrated the formation of a broad range of nano-structures-including many configurations never before observed. Some contained hollow chambers, round pegs, rods, and winding shapes. "This was really a Herculean effort on the part of Atikur," Yager said. "The multi-layer samples covered a staggering range of combinations." The scientists used scanning electron microscopy (SEM) to probe the nanoscale features, getting cross-sectional details of the emergent structures. A focused electron beam bombarded the sample, bouncing off surface features before being detected to enable reconstruction of an image depicting the exact configuration. They complemented this with x-ray scattering at Brookhaven's National Synchrotron Light Source II-another DOE Office of Science User Facility. The penetrative scattering technique allowed the researchers to probe the internal structure. "CFN brings together a unique concentration of skills, interests, and technology," said CFN Director and coauthor Charles Black. "In one facility, we have people interested in creating, converting, and measuring structures-that's how we can have these kinds of unanticipated and highly collaborative breakthroughs." This fundamental breakthrough substantially broadens the diversity and complexity of structures that can be made with self-assembly, and correspondingly broadens the range of potential applications. For example, intricate three-dimensional nanostructures could yield transformative improvements in nano-porous membranes for water purification, bio-sensing, or catalysis. This work was supported by the DOE Office of Science. Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization. Scientific paper: "Non-native Three-dimensional Block Copolymer Morphologies Note that this link will not work until the paper is published.

News Article | February 28, 2017

BOSTON--(BUSINESS WIRE)--GE (NYSE:GE) announced today the appointment of seven new company officers. Adrian Button has been promoted in his current role to Vice President of Supply Chain for Industrial Solutions, GE Energy Connections. Adrian joined GE in 1998 as a Quality Engineer and has held several operations leadership positions with GE Aviation, Unison Industries and GE Oil & Gas. Prior to joining GE Energy Connections, Adrian served as General Manager of Turbo Machinery Solutions for GE Oil & Gas covering the Middle East and North Africa region and General Manager of the Global Operations team. Adrian earned his bachelor’s degree in mechanical engineering from the University of Glamorgan in the United Kingdom. Buckmaster “Buck” de Wolf has been promoted to Chief Intellectual Property Counsel for GE and General Counsel for GE Global Research. Buck has been at GE for more than eleven years in senior legal roles at GE Corporate and GE Global Research. Prior to joining GE, Buck was a Partner at Howrey in San Francisco, CA. He earned his bachelor’s degree in economics from Middlebury College and his juris doctorate from Boston College. Danny Di Perna has been appointed Vice President, Global Sourcing for GE Power. Prior to joining GE, Danny was Pratt & Whitney’s Senior Vice President of Operations, responsible for new product development, sourcing, manufacturing, supply chain, supplier quality and production engine assembly. Danny has more than 27 years of experience within the aerospace industry, including 24 years with United Technologies Corporation. He earned his bachelor’s degree in mechanical engineering from Concordia University and his master’s in business administration from McGill University. Amit Phadnis has been appointed Vice President, Chief Technology Officer- Imaging, GE Healthcare. In this role, Amit will drive digitization, software and cross modality initiatives across the Imaging business. Amit joins GE from Cisco Systems where, most recently, he was the India Site Leader and Senior Vice President of Engineering for the Core Software Group. Prior to working at Cisco Systems, Amit held leadership roles at Motorola, Tata Elxsi and Silcom Automation Systems. Amit earned his master’s degree in electronics & communication from the Indian Institute of Science. Pascal Schweitzer has been appointed Vice President, Global Services at GE Transportation. Pascal joined GE in 2015 after GE’s acquisition of Alstom’s power and grid businesses, and was appointed General Manager for GE Power Services in Europe. Prior to joining GE, Pascal spent eight years at Alstom where he held several leadership positions, leading Gas Turbine global services in his most recent role. Pascal earned his master’s degree in finance from HEC Paris. Maria Sferruzza has been promoted to Vice President, Global Services for Turbomachinery Solutions at GE Oil & Gas. With more than twenty years of experience at GE Oil & Gas, Maria has held a variety of leadership roles in operations, sales, marketing, and services. Maria earned her master’s degree in industrial engineering from the Universita’ di Palermo, Italy. Anup Sharma has been promoted to Vice President, Chief Information Officer and Chief Application Architect at GE Digital. With twenty years of experience at GE, Anup has held Chief Information Officer roles at GE Power and GE Oil & Gas before his current position at GE Digital. Anup earned his bachelor’s degree in management information systems and business management from Huntington University in Indiana. GE (NYSE:GE) is the world’s Digital Industrial Company, transforming industry with software-defined machines and solutions that are connected, responsive and predictive. GE is organized around a global exchange of knowledge, the "GE Store," through which each business shares and accesses the same technology, markets, structure and intellect. Each invention further fuels innovation and application across our industrial sectors. With people, services, technology and scale, GE delivers better outcomes for customers by speaking the language of industry.

News Article | September 21, 2016

Last year, Christina Quasney was close to giving up. A biochemistry major at the University of Maryland, Baltimore County, Quasney's background was anything but privileged. Her father runs a small car-repair shop in the tiny community of Millersville, Maryland, and she was the first person in her immediate family to attend university. At the age of 25, she had already spent years struggling to make time both for her classes and the jobs she took to pay for them, yet was still far from finishing her degree. “I started to feel like it was time to stop fighting this losing battle and move on with my life,” she says. Quasney's frustrations will sound familiar to millions of students around the world. Researchers like to think that nothing matters in science except the quality of people's work. But the reality is that wealth and background matter a lot. Too few students from disadvantaged backgrounds make it into science, and those who do often find that they are ill-prepared owing to low-quality early education. Few countries collect detailed data on socioeconomic status, but the available numbers consistently show that nations are wasting the talents of underprivileged youth who might otherwise be tackling challenges in health, energy, pollution, climate change and a host of other societal issues. And it's clear that the universal issue of class is far from universal in the way it plays out. Here, Nature looks at eight countries around the world, and their efforts to battle the many problems of class in science. United States: How the classroom reflects class divide China: Low pay powers brain drain United Kingdom: The paths not taken Japan: Deepening divisions Brazil: Progressive policy pays off India: Barriers of language and caste Kenya: Easy access but limited prospects Russia: Positive policy, poor productivity By Jane J. Lee Quasney is lucky by global standards. She lives in an exceedingly rich country that is brimming with educational opportunities and jobs. Yet for students who share her struggles to make ends meet, the US higher-education system can pose one obstacle after another. “It starts in high school,” says Andrew Campbell, dean of the graduate school at Brown University in Providence, Rhode Island. Government-supported early education is funded mainly at the state and local level, he notes, and because science courses are the most expensive per student, few schools in the relatively poor districts can afford to offer many of them. Students from these districts therefore end up being less prepared for university-level science than are their wealthier peers, many of whom attended well-appointed private schools. That also puts the students at a disadvantage in the fiercely competitive applications process: only about 40% of high-school graduates in the lowest-income bracket enrolled in a university in 2013, versus about 68% of those born to families with the highest incomes. The students who do get in then have to find a way to pay the increasingly steep cost of university. Between 2003 and 2013, undergraduate tuition, fees, room and board rose by an average of 34% at state-supported institutions, and by 25% at private institutions, after adjusting for inflation. The bill at a top university can easily surpass US$60,000 per year. Many students are at least partly supported by their parents, and can also take advantage of scholarships, grants and federal financial aid. Many, like Quasney, work part time. Nonetheless, some 61% of US students earning bachelor's degrees graduate with some debt — US$26,900, on average. For those who go on to graduate programmes, tuition is usually paid for by a combination of grants and teaching positions. But if graduate students have to worry about repaying student loans, that can dissuade them from continuing with their scientific training. Several initiatives are under way around the country to ease the way for science students from disadvantaged backgrounds, among them is the $14-million INCLUDES programme announced earlier this year by the US National Science Foundation. But for students such as Quasney, staying in science can still be a matter of luck. One evening last year, she says, Michael Summers, a structural biologist at the university, happened to have dinner at the restaurant where she was hosting and waiting tables. That chance encounter led Quasney to join Summers' laboratory in January, and it was a revelation. Before, she had felt that some of her professors had forgotten what it was like to be a struggling student. Summers' lab is the exact opposite, she says. “There's no judgements and he doesn't discriminate.” Her experiences have helped her to understand what she can expect when she applies to graduate school and pursues a career in research. “I'm gonna go for it,” she says. “Go big or go home.” By David Cyranoski It is no accident that China currently produces more science PhDs than any country in the world. To combat large-scale poverty, especially in the interior provinces, the communist government in Beijing is trying to make education equally available to everyone. To help the poor, for example, Beijing sets tuition fees low and forbids raising them. Just 5,000 yuan (US$750) per year is enough for entry into premier institutions such as Tsinghua University in Beijing. And for those unable to come up with that sum, the country has national scholarship programmes, including tax-free loans and free admission. Meanwhile, to help integrate China's 55 ethnic minorities, which are also often poor, most provinces give bonus points to minority students who take the Gaokao: a university entrance examination that is the most important threshold to pass on the way to an academic career. A quota system ensures that students from remote regions such as Xinjiang and Tibet are represented at elite schools. China even has 12 universities that are dedicated to minorities. Beneath the surface, however, the reality of Chinese science often falls short of its egalitarian ideals. Children of senior government leaders and private business owners account for a disproportionate share of enrolment in the top universities. And students hesitate to take on the work-intensive career of a scientist when easier, and usually more lucrative, careers await them in business. According to Hepeng Jia, a journalist who writes about science-policy issues in China, this is especially true for good students from rich families. As a result, says Jia, scientists usually come from poorer families, get less support from home and work under a heavier financial burden. The situation is exacerbated by the low salaries, he says. The average across all scientific ranks is just 6,000 yuan per month, or about one-fifth of the salary of a newly hired US faculty member. Things are especially tough for postdoctoral researchers or junior-level researchers “who can hardly feed their families if working in bigger cities”, says Jia. This leads many scientists to use part of their grants for personal expenses. That forces them to make ends meet by applying for more grants, which requires them to get involved in many different projects and publish numerous papers, which in turn makes it hard to maintain the quality of their work. Many Chinese researchers escape that trap by seeking positions overseas. Thousands of postdoctoral researchers will go abroad in 2016 with funding from the China Scholarship Council, and many more will find sponsors abroad to fund them. But China has also been able to lure some of the most prominent of these researchers back home. Cao Kai, a researcher at the Science and Technology Talent Center of the science ministry in Beijing, released a survey in April that found one such returning scientist was rewarded with a stunningly high annual salary of 800,000 yuan. But that is not the norm, Kai says. It was just one extreme case he and his colleagues raised to convince “the government to raise the salary of professors at public universities”. That, he says, would go a long way to attracting and retaining talent in science, regardless of social background. By Elizabeth Gibney For the most part, science in the United Kingdom is egalitarian — for those who have already made it their career. A 2016 study found that, unlike in law or finance, researchers from lower-income backgrounds are paid no less than their more advantaged peers (D. Laurison and S. Friedman Am. Soc. Rev. 81, 668–695; 2016). But getting into science is different. The same study found that only 15% of scientists come from working-class households, which comprise 35% of the general population (see 'Elite careers'). Another found that, over the past 25 years, 44% of UK-born Nobel-prizewinning scientists had gone to fee-paying schools, which educate 7% of the UK population (P. Kirby Leading People 2016 The Sutton Trust, 2016). “There's a class barrier to the professions,” says Katherine Mathieson, chief executive of the British Science Association, “but it's more extreme for science.” One hurdle is aspirational. In an ongoing, 10-year study, a group from King's College London found that most English 10–14 year olds find science interesting. But those from working-class backgrounds rarely saw it as a career — perhaps because they seldom encountered people in science-related jobs (ASPIRES: Young People's Science and Career Aspirations, Age 10–14 King's College London, 2013). To tackle this, the King's team is working with London schools on a pilot programme to show children aged 11 to 15 how science fits into everyday life — by examining the chemicals in food, for example — and how science skills are relevant in a range of jobs. Early results are promising, and the team plans to expand the programme next year. Another barrier could be that UK students who are interested in a science career often need to abandon other subjects at the age of 16. “People from lower-income backgrounds who are unaware of the range of possible science careers might see it as a high-risk gamble,” says Mathieson. A third issue is the effect of a sudden trebling of annual university fees to £9,000 (US$12,000) in 2012. “I suspect that fees could be a massive deterrent to those who grow up in families that have to worry about the basic level of income,” says Mathieson. The danger, she adds, is that a failure to represent all backgrounds will not only squander talent, but increasingly isolate science from society. That disconnect was apparent in the Brexit referendum in June, when more than half of the public voted to leave the European Union, compared with around one in ten researchers. “That diverging world view is a real problem,” says Mathieson, “both for the quality of research and for scientists' place in society.” By David Cyranoski In Japan, inequalities in wealth and status do not reach the extremes found in China and India. Nonetheless, graduate education and academic research have become less attractive options over the past decade, especially for the underprivileged. Some warn that this could make research a preserve of the wealthy — with grave social costs.“It is an emerging issue in Japan,” says Yuko Ito, who researches science policy at the Japan Science and Technology Agency in Tokyo, a major science funder. A big part of the problem is the rise in tuition fees: even at the relatively inexpensive national universities, the ¥86,000 (US$840) in entrance and first-year tuition fees students paid in 1975 would make little dent in the ¥817,800 they've been paying since 2005. In addition, thanks to Japan's long economic contraction, parents are chipping in 19% less for living costs on average than they did a decade ago. This leaves students increasingly dependent on 'scholarships' — which in Japan are mainly loans that need to be paid back. Half of all graduate students have taken out loans, and one-quarter owe more than ¥5 million. “Many students just can't come up with the tuition and living costs to become researchers,” says Koichi Sumikura, a professor of science policy at the National Graduate Institute for Policy Studies in Tokyo. Even for those who make it through university on loans, jobs that would make the debt worthwhile are far from guaranteed. In their prime years, between the ages of 30 and 60, one-third of university graduates earns less than ¥3 million per year. “In these conditions,” says Ito, “one would hesitate to follow an academic career.” The social divide in higher education already shows. A crucial step to becoming a researcher is to enter a powerful institution such as the University of Tokyo, where the average income of a student's family is twice the national average. “If this situation continues,” Ito says, “science will become something that only the rich will hold an interest in, and research will grow distant from solving current social problems.” The government has taken stock of the issue. A government plan for 'investment in the future', announced on 2 August, promises to increase funding for scholarships that need not be repaid as well as to boost the availability of tax-free student loans. But the government has yet to take up a more specific examination of the relationship between success as a researcher and economic factors, says Sumikura. “That will be an important topic in the future,” he says. By Jeff Tollefson In Brazil, inequalities in wealth are extreme by almost every measure — including education. The government-run schools are so bad that they are avoided by all but the poorest families. As recently as 2014, just 57% of the country's 19-year-olds had completed high school. And yet there are signs of progress, especially in science, technology, engineering and medicine. In 2011, for example, Brazil created Science Without Borders, a programme to send tens of thousands of high-achieving university and graduate students to study abroad. Because students from wealthier families have by far the best primary and secondary education, they might have been expected to dominate the selection process. But by the end of the first phase this year, more than half of the 73,353 participants had come from low-income families. “These statistics really caught us all by surprise,” says Carlos Nobre, a climate scientist who formerly headed of one of the public foundations that fund Science Without Borders. In São Paulo, meanwhile, the medical school at the prestigious University of Campinas (UNICAMP) gives preference to admitting gifted students from government-run schools. The programme started in 2004 after research suggested that out of those with similar test scores prior to admittance, predominantly poor government-school students tended to perform better at UNICAMP than did their counterparts from private schools. The former comprised 68% of this year's entering class. Carlos Henrique de Brito Cruz, who launched the UNICAMP initiative when he was the university rector, suspects that part of the answer is quite simple. “These students had more obstacles to overcome,” he says. “And when you put them in an environment where the obstacles are more or less the same, they tend to realize more of their potential.” Brazil may also be seeing the fruits of the government's effort to improve scientific literacy and push more students into science careers, which gained momentum after the inauguration of Luiz Inácio Lula da Silva as president in 2003. A division at the federal Ministry of Science, Technology and Innovation focuses entirely on 'social inclusion', with programmes to improve public schools and promote research in fields that affect local communities, such as nutrition and sustainability. The poor quality of secondary education remains a substantial problem that could take a generation or more to address, experts say. Nonetheless, existing initiatives could be boosting the quality of government schools enough for ambitious students to excel, says Nobre. The next question, he says, is whether these students will be able to bolster innovation in Brazilian science. “Now that they are coming into the market, we will have to start evaluating very quickly what happened to these students.” By T. V. Padma Despite the renown of technology hubs such as Bangalore and universities such as the multicampus Indian Institute of Technology, vast numbers of talented students in India never get to realize their full potential owing to poor rural schools, language barriers and the caste system. Especially outside the cities, higher education — including science — largely remains a privilege of the rich, the politically powerful and the upper castes. India's national census does not collect data on caste, rural or gender representation in science, nor do the country's science departments. Nonetheless, says Gautam Desiraju, a chemist at the Indian Institute of Science in Bangalore, it is clear that rural Indian students are hampered by a lack of good science teachers and lab facilities, and are unaware of opportunities to enter mainstream science (see The barriers are even higher for rural girls, who are discouraged from pursuing higher studies or jobs, and for girls from poor urban families, who are expected to take jobs to contribute to their dowries. Many rural students are also hampered by their poor English, the language that schools often use to explain science. “Teachers from elite colleges and interview and selection committees are often biased against such students,” says immunologist Indira Nath, at the Indian National Science Academy in New Delhi. Caste — the hereditary class system of Hindu society — is officially not an issue. India's constitution and courts have mandated that up to half of the places in education and employment must be reserved for people from historically discriminated-against classes. However, a clause excludes several of India's top science centres from this requirement. And in reality there is an “unintentional, subtle or hidden discrimination against students from reserved categories, right from high school to college levels”, says Shri Krishna Joshi, a scientist emeritus at the National Physical Laboratory in New Delhi. Teachers do not encourage them as much as they do students from upper castes. As a result, he says, “poor students from reserved categories in turn often have psychological barriers and believe they cannot compete with the others”. Still, says Desiraju, there are signs of progress. For a long time, Indian officials assumed that all they had to do was set up centres of scientific excellence and the effects on education would simply trickle down to the masses. “But now,” he says, “agencies are beginning to adopt a more bottom-up approach” that seeks to find talented people at the lowest economic levels. At the University of Delhi South Campus, geneticist Tapasya Srivastava sees the effects of that shift. “Competitiveness for higher science education is increasing across all caste-based categories and gaps are dissolving,” she says. “Talented young researchers are getting admissions based on their merit alone and not because of the constitutional provision,” agrees Desiraju. But there is much still to be done, he says. “Finding the right talented girl or boy in a small town or village in India is often like finding a needle in a haystack.” In Kenya, where around 40% of the population lives on less than US$1.25 a day, class matters surprisingly little for who makes it into science. As one of Africa's fast-growing 'lion' economies, the country has seen university enrolment more than double since 2011, reaching more than 500,000 last year. The government subsidizes tuition fees for poor secondary-school students who get good grades in science, and there are loans available to help them with living expenses. At the postgraduate level, however, the lack of opportunities in Kenya means that many science hopefuls have to do part of their training abroad. “The problem for me wasn't getting into science, it was staying in,” says Anne Makena, a Kenyan from a lower-class background with an undergraduate degree in biochemistry from Moi University in Eldoret. She now has a Rhodes scholarship to finish her PhD in chemical biology at the University of Oxford, UK. For those staying at home, the surest path to a research career is to get a job with foreign-funded organizations such as the International Centre of Insect Physiology and Ecology (ICIPE) in Nairobi, or the partnership between the Kenya Medical Research Institute (KEMRI) and the UK Wellcome Trust. But competition is fierce, and it can take years to get accepted. This is when graduates from a poorer background are more likely to give up, says Makena. They are drawn by lucrative private-sector salaries and mindful of the need to contribute financially to their families, whereas wealthier students can afford to wait. Another source of uncertainty is Kenyan universities' struggle to secure enough operating funds from the government. The shortfall has led vice-chancellors in the country's public universities to propose up to a five-fold rise in tuition fees for resource-intensive courses, including science. If this happens and government subsidies do not keep pace, poorer students might forego science courses for cheaper degrees. That would be a pity, says Baldwyn Torto, head of behavioural and chemical ecology at ICIPE, because Kenyan students from modest backgrounds make excellent scientists in his experience. “You find kids from poorer families performing equally well, if not better, than kids from wealthier families,” he says. By Quirin Schiermeier Following the Soviet Union's collapse in 1991, Russia was quickly given over to untamed capitalism and increasing inequity. Yet the country retained its socialist ideals in education: even now, Russia produces a large share of its science students and researchers from low- and middle-income backgrounds. “There is a national consensus in Russia regarding the value of equal opportunities in education for the modernization of our country,” says Dmitry Peskov, who directs the young professionals division of the Moscow-based Agency for Strategic Initiatives, which promotes economic innovation in Russia. The country hosts some 3,000 universities and higher learning institutes, and about half of its secondary-school graduates go on to attend them. The average among all Organisation for Economic Co-operation and Development countries is about 35%. In peripheral regions such as the Urals or Siberia, where local governments are keen to develop scientific and engineering capacity, teachers identify talented students as early as ages 4 to 6. If they continue to show promise, they are encouraged to enrol at local universities, whose tuition-free programmes may focus on local needs such as agricultural technology. Children who demonstrate exceptional skills in science, art, sports or even chess may earn admission to the Sirius educational centre in Sochi on the Black Sea. This centre, backed by Russian president Vladimir Putin, was set up after the 2014 Winter Olympics to help Russia's most gifted youths develop their talent with support from leading scientists and professionals. Since December 2015, prospective students who succeed in local or national science competitions and maths Olympiads can also hope to secure a presidential grant worth 20,000 roubles (US$307) per month. These grants allow hundreds of students from lower social backgrounds to study at the nation's top universities on the sole condition that they will stay in Russia for at least five years after graduation. But despite such efforts, Russia's science output remains relatively low. One reason, Peskov says, is the Russian science community's isolation. For all their skills and social diversity, Russian researchers tend to speak poor English and are underrepresented in international meetings and collaborations. Uncertainty over the Russian government's future support of science adds to the problem. “Lucrative jobs in finance, business administration or industry are much more popular among well-trained young Russians than is a risky academic career,” he notes.

Gurao N.P.,Indian Institute of Science | Kapoor R.,Bhabha Atomic Research Center | Suwas S.,Indian Institute of Science
Acta Materialia | Year: 2011

The evolution of microstructure and texture during room temperature compression of commercially pure Ti with four different initial orientations were studied under quasi-static and dynamic loading conditions. At a low strain rate ̇ = 3 × 10-4 s-1 all the different initial textures yielded the same end texture, despite different microstructural evolution in terms of twin boundaries. High strain rate deformation at ̇ = 1.5 × 103 s-1 was characterized by extensive twinning and evolution of a texture that was similar to that at low strain rate with minor differences. However, there was a significant difference in the strength of the texture for different orientations that was absent for low strain rate deformed samples at high strain rate. A viscoplastic self-consistent model with a secant approach was used to corroborate the experimental results by simulation. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rao B.N.,Indian Institute of Science | Fitch A.N.,European Synchrotron Radiation Facility | Ranjan R.,Indian Institute of Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Morphotropic phase boundary (MPB) systems are characterized by the coexistence of two ferroelectric phases and are associated with anomalous piezoelectric properties. In general, such coexistence is brought about by composition induced ferroelectric-ferroelectric instability. Here we demonstrate that a pure ferroelectric compound Na1/2Bi1/2TiO 3 (NBT) exhibits the coexistence of two ferroelectric phases, rhombohedral (R3c) and monoclinic (Cc), in its equilibrium state at room temperature. This was unravelled by adopting a unique strategy of comparative structural analysis of electrically poled and thermally annealed specimens using high resolution synchrotron x-ray powder diffraction data. The relative fraction of the coexisting phases was found to be highly sensitive to thermal, mechanical, and electrical stimuli. The coexistence of ferroelectric phases in the ground state of the pure compound will have significant bearing on the way MPB is induced in NBT-based lead-free piezoceramics. © 2013 American Physical Society.

Harshan J.,Monash University | Rajan B.S.,Indian Institute of Science
IEEE Transactions on Wireless Communications | Year: 2013

Constellation Constrained (CC) capacity regions of two-user Gaussian Multiple Access Channels (GMAC) have been recently reported, wherein an appropriate angle of rotation between the constellations of the two users is shown to enlarge the CC capacity region. We refer to such a scheme as the Constellation Rotation (CR) scheme. In this paper, we propose a novel scheme called the Constellation Power Allocation (CPA) scheme, wherein the instantaneous transmit power of the two users are varied by maintaining their average power constraints. We show that the CPA scheme offers CC sum capacities equal (at low SNR values) or close (at high SNR values) to those offered by the CR scheme with reduced decoding complexity for QAM constellations. We study the robustness of the CPA scheme for random phase offsets in the channel and unequal average power constraints for the two users. With random phase offsets in the channel, we show that the CC sum capacity offered by the CPA scheme is more than the CR scheme at high SNR values. With unequal average power constraints, we show that the CPA scheme provides maximum gain when the power levels are close, and the advantage diminishes with the increase in the power difference. © 2012 IEEE.

Roy S.,Indian Institute of Science | Rosenthal U.,Leibniz Institute for Catalysis at the University of Rostock | Jemmis E.D.,Indian Institute of Science
Accounts of Chemical Research | Year: 2014

ConspectusTransition metals help to stabilize highly strained organic fragments. Metallacycles, especially unsaturated ones, provide much variety in this area. We had a sustained interest in understanding new C-C bond formation reactions affected by binuclear transition metal fragments Cp2M. One such study led to the exploration of the bimetallic C-C cleavage and coupled complexes, where the acetylide ligands bridge two metal atoms. The underlying M-C interaction in these complexes inspired the synthesis of a five-membered cyclocumulene complex, which opened a new phase in organometallic chemistry. The metallacyclocumulene produces a variety of C-C cleavage and coupled products including a radialene complex. Group 4 metallocenes have thus unlocked a fascinating chemistry by stabilizing strained unsaturated C4 organic fragments in the form of five-membered metallacyclocumulenes, metallacyclopentynes, and metallacycloallenes. Over the years, we have carried out a comprehensive theoretical study to understand the unusual stability and reactivity of these metallacycles.The unique (M-Cβ) interaction of the internal carbon atoms with the metal atom is the reason for unusual stability of the metallacycles. We have also shown that there is a definite dependence of the C-C coupling and cleavage reactions on the metal of metallacyclocumulenes. It demonstrates unexpected reaction pathways for these reactions. Based on this understanding, we have predicted and unraveled the stabilization factors of an unusual four-membered metallacycloallene complex. Indeed, our prediction about a four-membered heterometallacycle has led to an interesting bonding situation, which is experimentally realized. This type of M-C bonding is intriguing from a fundamental perspective and has great relevance in synthesizing unusual structures with interesting properties.In this Account, we first give a short prologue of what led to the present study and describe the salient features of the structure and bonding of the metallacyclocumulenes. The unusual reaction pathway of this metallacycle is explored next. Similar features of the metallacyclopentynes and metallacycloallenes are briefly mentioned. Then, we discuss the exploitation of the unique M-C bonding to design some exotic molecules such as a four-membered metallacycloallene complex. Our efforts to build a conceptual framework to understand these metallacycles and to exploit their chemistry continue. © 2014 American Chemical Society.

Agency: Cordis | Branch: FP7 | Program: CSA | Phase: ICT-2009.9.1 | Award Amount: 695.74K | Year: 2010

SYNCHRONISER will boost the impact of the EU-India research policy dialogue in ICT using Foresight techniques. A COMMITTEE of stakeholders from both regions will identify research paths for joint research priorities noted at the EU-India March 2009 Information Societies Joint Working Group. SYNCHRONISER addresses 2 objectives feeding the EU-India policy dialogue and strengthens the international dimension of their ICT research programme: i) matching EU-India co-funding opportunities; ii) long term Indian research perspectives aligned with EU priorities. A Foresight exercise will identify future R&D trends to influence EU-India R&D policy. Input will include a comprehensive survey of best-in-class researchers across India using Delphi research techniques as a keynote activity resulting in publication of a Trend Study and Roadmap Report at the end of the Foresight process. This Study will act as an encyclopaedia for future EU-India joint research initiatives by highlighting current joint research scenarios and long-term perspectives. The SYNCHRONISER Consortium is well-balanced and geographically well-distributed, Indo-European, public-private-partnership with in-depth knowledge of the ICT sector in both regions and is part of a broad international network of public and private organizations, research centres and universities. The Consortium will benefit from its partners vast experience in EU-India Horizontal Support Action projects and strong support by the Government of Indias Department of Information Technology to establish synergies with other policy dialogue initiatives (e.g. INCO-NETS, BILATS, and other EU-India ICT projects). The GoI DIT will also assist in organizing high-level events involving policy-makers. SYNCHRONISER will ensure project dissemination through events, a project website, etc. The project target groups include ICT communities, policy-makers and other stakeholders from both regions

Yoon M.,Pohang University of Science and Technology | Suh K.,Pohang University of Science and Technology | Natarajan S.,Pohang University of Science and Technology | Natarajan S.,Indian Institute of Science | Kim K.,Pohang University of Science and Technology
Angewandte Chemie - International Edition | Year: 2013

Proton-conducting materials are an important component of fuel cells. Development of new types of proton-conducting materials is one of the most important issues in fuel-cell technology. Herein, we present newly developed proton-conducting materials, modularly built porous solids, including coordination polymers (CPs) or metal-organic frameworks (MOFs). The designable and tunable nature of the porous materials allows for fast development in this research field. Design and synthesis of the new types of proton-conducting materials and their unique proton-conduction properties are discussed. Pores and protons: Development of new types of proton-conducting materials is important in fuel-cell technology. Newly developed proton-conducting materials formed from modularly built porous solids, including coordination polymers (CPs) or metal-organic frameworks (MOFs) are discussed (see scheme). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

News Article | November 17, 2015

Raghu Murtugudde is a professor at the University of Maryland's Earth System Science Interdisciplinary Center (ESSIC) and the Department of Atmospheric and Oceanic Science. He is currently a visiting professor at the Indian Institute of Science Education and Research in Pune, India. Murtugudde contributed this article to Live Science's Expert Voices: Op-Ed & Insights. When living standards visibly contrast — such as in crowded urban centers, where slums are scattered amid wealthy neighborhoods — studies have shown cooperation between the rich and the poor falters. In the context of climate change, this lack of cooperation between rich and poor manifests itself in international negotiations. Wealthy countries tend to ignore the issues and voices of poor countries , which often tend toward the immediate and existential — education and health care, for example. It's a situation made ever more tragic since loss of life due to climate extremes tends to be high in poor countries, where recovery from natural disasters is also slower. 2015 may be a critical year for humanity to fix that disconnect, with major efforts to smooth out the lack of trust between rich and poor nations. This year, the global community will try to flesh out a democratic agreement on climate action and develop common targets to elevate the poor, and women, from abject poverty. The follow-up agreement to the now-expired Kyoto protocol will be finalized at the Conference of Parties-21 (COP21), to be held in Paris in December under the auspices of the United Nations Framework Convention on Climate Change. And the U.N.'s Millennium Development Goals are set to expire at the end of 2015, after which the U.N.'s focus will shift to its Sustainable Development Goals, which are designed to tackle poverty and enhance climate resilience across the planet. The world is still coming to grips with the latest assessment report issued by the Intergovernmental Panel on Climate Change (IPCC) in 2014, which states with higher certainty than ever that climate change is caused by human activities . Despite the continuing efforts by the climate skeptics, survey after survey show that communities across the globe support actions to tackle climate change. Some climate scientists are increasingly alarmed by the glacial pace of negotiations under COP and are calling for more authoritative approaches to take action on climate change. This debate is cast as an earnest effort to save the planet, but is often dominated by the Global North, i.e., developed economies such as the United States and Europe (and Australia, despite its geographic location), and perceived as a barrier to their development by the Global South represented by growing economies such as those in Africa, India, China, and Brazil. However, in a recent policy analysis for the journal Nature, Nico Stehr of the European Center for Sustainability Research notes that many scientists are advocating imposing ad hoc and broad limitations on emissions, and he sounded a cautionary note against sidestepping democracy by ignoring the needs and demands of the Global South in adapting to climate impacts. This caveat is a reminder of the paradox first noted in the 1940s by economics Nobel laureate Friedrich Hayek: Society tends to associate scientific advances with a desire for increased control of human activities — which is now seen in various forms of data tracking by technology, perfect for maximizing consumption. There is a sense of information overload due to increasingly alarming daily headlines about climate change impacts on the air we breathe, the water we drink and the food we consume. Since there are no clear and tangible solutions offered, there is the danger of a creeping sense of "impossible" imposed on our way of life. While climate warming may be global, the majority of impacts will be local. No human lives in a global mean, or average, climate, or experiences global mean temperature, or faces global mean sea level rise. Global warming will almost certainly create beneficial effects for some environments and economies, thus creating winners as well as losers. Those complexities will give rise to dissenting voices in discussions of how to deal with climate change, and world leaders must resolve to hear these voices carefully. Two examples highlight this disparity beautifully and succinctly. One is an annual survey of a representative sample of more than 1,000 U.S. residents regarding climate change views in this country — a wealthy, developed, democratic nation — and the other is a global survey of more than a million people, 80 percent of whom live in developing countries. [5 Places Already Feeling the Effects of Climate Change ] Global Warming's Six Americas is the ongoing U.S. survey, conducted by Yale University and George Mason University, and it divides citizens based on their sense of urgency related to climate change. The six categories are alarmed, concerned, cautious, disengaged, doubtful and dismissive. The survey has tracked the opinions and attitudes of these six Americas since 2008.  Importantly, five of the six Americas rank improved public health as among the top benefits of reducing fossil fuel use. Even though "alarmed" America has grown and "dismissive" America has shrunk since 2008, all six categories expressed concern about increased government regulation and higher energy prices as a result of actions to combat global warming.  The six Americas also differ in their opinion of who influences the legislators most: media, campaign contributors, energy companies or individuals. However, all six Americas seem to agree that action is needed and that they would support measures such as revenue-neutral carbon taxes, meaning the proceeds would be used to create green jobs, pay down the national debt, or decrease pollution by promoting cleaner energy options.  The My World global survey was conducted by the U.N. and the Overseas Development Institute, a U.K.-based independent think tank focused on international development and humanitarian issues. That survey predominantly captures the voices of the poor from developing countries.  As other surveys and studies have found, the results of this survey suggest that climate change is not a high-priority issue for the poor. But surprisingly, poverty reduction and international aid received similarly low-priority rankings.  Rather, the poor assign the highest priority to education, health care, job opportunities, and honest and responsible government. These voices have clearly not been heard by the developed nations of the U.N., who formulated the Sustainable Development Goals and gave top billing to the eradication of poverty worldwide by 2030.  The U.N. defines extreme poverty as an income of less than $1.25 a day, whereas the My World survey shows that people measure poverty relative to the average income of their community. Those in poverty do recognize that climate change will affect their top priorities, in part by exacerbating their dependence on science and technology created by the developed world.  Combating global warming is clearly a noble and necessary goal. It is indeed a testimony to the global spirit that the entire world is participating in COP21, where all leading polluter nations will offer their Intended Nationally Determined Contributions (INDCs) to the global reductions in carbon emissions.  The INDC is a new, bottom-up framework for continued global action against global warming and offers an alternative to the generally failed top-down approach taken under the Kyoto protocol. The INDC lets the nations define their role in helping keep the global temperature rise within 2 degrees Celsius of temperatures at the beginning of the Industrial Revolution.  The process is aimed at being more democratic: It allows nations to commit to emission reductions with explicit adaptations to climate change impacts and renewable energy growth — within the context of each nation's capabilities and priorities, and the support they'll need to get there. This development is just another indication of the robustness of democracy and its global success in engendering global participation.  In an even more heartwarming signal of the human spirit, many large corporations like the United Parcel Service, Pepsico and Siemens have developed and implemented their own plans to reduce their emissions as well as water and energy usage. We need to be more vigilant at the local level, and resolve to hear what prosperous and poor individuals alike see as priorities as we continue to work toward common goals for the planet. The Global North-South divide is the most serious impediment to global actions on issues such as climate change that threaten the global commons. Just as an airplane cannot be made safer just for those in first class, Earth cannot be made safer just for the rich countries as climate-change impacts begin to multiply and grow. Democratic governance at the global level is the only tool for success, and the most consistent with human dignity.  Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science. Real Climate Change as World Does More Than 'Show Up' (Op-Ed) Is Climate Change Response 'Fight or Flight' or 'Rest and Digest'? (Op-Ed) Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

News Article | November 11, 2015

Indian alliance India’s ministry of human-resource development launched a research alliance between 16 Indian Institutes of Technology (IITs) and the Indian Institute of Science (IISc), Bangalore, on 5 November. The Impacting Research Innovation and Technology (IMPRINT) programme is the country’s first pan-IIT and IISc initiative. Its ten topics range from water resources and river systems to nanotechnology. The initiative has an initial budget of 10 billion rupees (US$150 million). Google heart boost On 8 November, Google’s life-sciences branch and the American Heart Association announced that each would contribute US$25 million to a $50-million project to make breakthroughs in understanding, treating and preventing coronary heart disease, which causes one in every three US deaths. The money will all go to one interdisciplinary team, led by a single investigator and advised by an as-yet unchosen panel. Applications will open in January. Manhattan Project gets national park The US Department of Energy and the National Park Service established a national park on 10 November to preserve historic sites from the 1940s Manhattan Project to develop atomic bombs. The park covers three sites — Oak Ridge in Tennessee; Hanford in Washington; and Los Alamos in New Mexico. Each site worked on different aspects of nuclear-weapons design and uranium and plutonium production. Preserved facilities include Oak Ridge’s X-10 graphite reactor, which converted uranium-238 to plutonium-239; Hanford’s B reactor, the first to produce large amounts of plutonium; and the V-Site buildings in Los Alamos, where components for the first nuclear bombs were assembled (pictured: the Trinity bomb). Science unmuzzled Canadian scientists have been thrilled by their new Liberal government’s first week in office. On 5 November, the government reinstated the mandatory long-form population census, which scientists and policymakers rely on for social data. And on 6 November, the new Minister of Innovation, Science and Economic Development, Navdeep Bains, ‘unmuzzled’ government scientists, declaring that they no longer need to seek permission from communications officers to speak with the media or public. Prime Minister Justin Trudeau was sworn in on 4 November and announced Kirsty Duncan in the new post of science minister (see page 146 for more). Ebola-free nations The World Health Organization (WHO) declared the end of the Ebola outbreak in Sierra Leone on 7 November. On that date, the country met the WHO’s criteria of 42 days — twice the maximum incubation period for the virus — since the last case was cured. Liberia was declared Ebola-free on 3 September, leaving Guinea as the only remaining country in the region with continuing infections. One new case of Ebola was recorded in Guinea in the week up to 1 November, and three infections were reported in the previous week. The WHO warns that there is a risk of further cases to come. Amazonian park Peruvian President Ollanta Humala announced the creation of the Sierra del Divisor National Park on 8 November, a move long sought by scientists and conservationists. Encompassing 1.3 million hectares, the park protects crucial Amazonian biodiversity, including endangered plant and animal species, and is also home to uncontacted indigenous groups. The philanthropic Andes Amazon Fund in Washington DC called the decision “one of the most significant rainforest conservation accomplishments in recent years”. Sierra del Divisor faces mining, logging and other threats that officials must continue to fend off. HFC curbs Governments agreed on 6 November to use the Montreal Protocol ozone treaty to regulate the climate impact of hydrofluorocarbons (HFCs), commonly used as refrigerants. HFCs were developed to replace chemicals that deplete the ozone layer (pictured is the ozone hole over the Antarctic in October this year), but they are powerful greenhouse gases. At a meeting in Dubai, 197 parties to the treaty agreed to manage HFCs under the protocol, but negotiators delayed debate about the details of any regulations until 2016. Obokata PhD blow Waseda University in Tokyo has revoked the doctorate of Haruko Obokata, formerly of the RIKEN Center for Developmental Biology in Kobe, Japan. Obokata was lead author on two papers published in Nature in January 2014 that reported the creation of pluripotent stem cells by subjecting body cells to acid; the method was called stimulus-triggered acquisition of pluripotency (STAP). Problems in the papers led to their retraction in July 2014. In October that year, after finding plagiarized passages and images in her 2011 PhD dissertation, the university gave Obokata a year to make corrections. But in its 2 November statement, the university committee judged her drafts inadequate. Euro advisers The seven researchers who will form a panel to provide the European Commission with independent scientific advice were named on 10 November. They include Rolf Dieter-Heuer, the outgoing head of CERN, Europe’s particle-physics laboratory near Geneva, Switzerland, and Julia Slingo, chief scientist at Britain’s Met Office in Exeter. The panel’s announcement marks the formal launch of the commission’s revamped system for obtaining scientific advice. Under that system, the panel will feed in advice to the commission by seeking input from national academies and the wider scientific community. See for more. Prize scoop On 10 November, Nature reporter Alexandra Witze took home the gold prize for magazine journalism at the 2015 AAAS Kavli Science Journalism Awards. The awards, which cover magazine, newspaper and television journalism, are funded by the Kavli Foundation and administered by the American Association for the Advancement of Science. The judges singled out Witze’s features for praise, including ‘The quake hunters’ (Nature 523, 142–144; 2015) and ‘The Pluto siblings’ (Nature 518, 470–472; 2015). Drug-cost probe The US Senate is investigating drug costs and price hikes resulting from mergers and acquisitions. On 4 November, two senators requested documents from four pharmaceutical companies relating to their communication with regulators and details on drugs that they acquired from other companies. Central to the investigation is Turing Pharmaceuticals in New York City, which caused outcry in September when it acquired the antiparasitic drug pyrimethamine (Daraprim) and increased its price by more than 5,000%. Turing’s chief executive, Martin Shkreli, said this week that the firm will most likely drop the price by about 10% before the end of the year. Oil giant quizzed New York state attorney-general Eric Schneiderman has launched an investigation into whether ExxonMobil deliberately misled investors about the risks of global warming. Schneiderman issued a subpoena on 4 November for records related to the oil company’s statements about climate change. Environmentalists have accused ExxonMobil, headquartered in Irving, Texas, of intentionally lying about the science underlying global warming and of funding climate-change sceptics to prevent the regulation of greenhouse gases. Company officials deny the claims, saying that the firm supports the implementation of a carbon tax. VW emission woes After an internal investigation, Volkswagen (VW) reported on 3 November that 800,000 of its cars show “irregularities” in fuel-consumption rates and carbon dioxide emissions, which may be different from those officially stated. The report comes on top of the company’s manipulation of nitrogen oxide tests in a scandal involving 11 million VW cars worldwide. Environmental groups claim that real-world CO emissions from cars in the European Union are up to 40% higher than the official values that manufacturers report based on idealized laboratory tests. The latest UNESCO Science Report highlights the striking progress made by sub-Saharan Africa in science, technology and innovation. Publications by nearly all 15 countries in the Southern Africa Development Community rose from 2005 to 2014. Article output almost tripled in Malawi and Mozambique, and more than doubled in South Africa and Tanzania. The 10 November report points to Malawi’s huge effort to attract foreign investment and increase science spending to offset its lack of natural resources. 16–20 November Physicists meet in Paris to celebrate 100 years of general-relativity theory. 18–22 November AORTIC 2015, the 10th International Conference on Cancer in Africa, is held in Marrakesh, Morocco.

News Article | February 15, 2017

The FireFly architecture features free-space optics communication links and represents an extreme design approach to meet the requirements of modern robust data center networks. Data centers (DCs)—facilities that are used to centralize the IT operations and equipment of an organization—represent a critical piece of modern networked applications, in both the private and public sectors. The trend toward DCs has been driven by a number of key factors, e.g., economies of scale, reduced management costs, better use of hardware (via statistical multiplexing), and the ability to elastically scale applications in response to changing workload patterns. In particular, a robust network fabric is fundamental for the success of DCs, i.e., to ensure that the network does not become a bottleneck for high-performance applications. In this context, the design of a DC network must satisfy several goals, including high performance (e.g., high throughput and low latency), low equipment and management costs, robustness to dynamic traffic patterns, incremental expandability to add new servers or racks, as well as other practical concerns (e.g., cabling complexity, and power and cooling costs). Currently available DC network architectures, however, do not provide satisfactory solutions to these requirements. There are two main problems with traditional static (wired) networks. They are either ‘overprovisioned’ to account for worst-case traffic patterns and thus incur high costs (e.g., with fat trees or Clos architectures), or they are ‘oversubscribed’ (such as with simple trees or leaf-spine architectures). Although the latter networks have low costs, they offer poor performance because of their congested links. In recent studies, attempts have been made to overcome these limitations by augmenting a static ‘core’ with some flexible links (radio-frequency or optical wireless). These augmented architectures do show some promise, but they provide only a small improvement in performance. Moreover, all these architectures involve high cabling costs and complexities. In our work,1 we envision an extreme design point to meet the requirements of modern DC networks rather than trying to incrementally improve the cost-performance tradeoffs, high cabling complexity, and rigidity of current DC architectures. In our architecture vision—known as FireFly—we use free-space optics (FSO) communication links to realize a fully flexible, all-wireless inter-rack fabric. FSO communication technology is particularly well suited to our aim because it offers very high data rates (tens of Gb/s) over longranges (more than 100m), while having low transmission power and a small interference footprint. A conceptual overview of our FireFly architecture vision is shown in Figure 1. In our design, each top-of-rack (ToR) switch has flexible (steerable) FSO links that can be dynamically reconfigured to connect to other ToRs. The controller reconfigures the topology to adapt to current traffic workloads. This vision provides several benefits over current DC architectures. For instance, our topological flexibility (if achieved correctly) provides a low-cost option (i.e., few switches and links) with performance comparable to more expensive overprovisioned networks. In addition, our all-wireless fabric eliminates cabling complexity and associated overheads (e.g., obstructed cooling). Our approach can also facilitate new and radical DC topology structures that would otherwise remain at the ‘paper design’ phase because of their cabling complexity. Lastly, our method of flexibly turning links on or off brings us closer to realizing the aim of energy-proportional DCs (and the flexibility enables easier incremental expansion of a DC). Figure 1. Schematic illustration of the FireFly architecture. FSO: Free-space optics. ToR: Top of rack. The unique characteristics of our approach (i.e., the FSO-based inter-rack links and the fully flexible topology) give rise to novel algorithmic, networking, and system-level challenges that need to be addressed before our vision can be made into a reality. First, we need to develop cost-effective and robust link technologies that have small form factors and that can be steered at short timescales to impart flexibility. Second, we require algorithmic techniques to design the efficient and flexible networks. Third, we need new network management solutions. These may include algorithms for the joint optimization problem of runtime topology selection and traffic engineering, as well as data-plane mechanisms to guarantee various consistency and performance requirements. In our recent work,1 we have demonstrated the viability of our FireFly architecture by building a proof-of-concept prototype (with commodity components) for a steerable, small-form-factor FSO device (see Figure 2). We have also developed practical heuristics to address the algorithmic and system-level challenges in the network design and management of our architecture. In addition, we have developed techniques to provide line-of-sight for FSO links in the FireFly architecture. For our steerable, small-form-factor FSO device, we have been exploring the use of microelectromechanical systems (MEMS) mirrors as a steering technology to steer the FSO beams with minimal latency. In this device, we use a collimated laser beam that is transmitted from the fiber collimator of an FSO terminal. The laser beam passes onto a gimbal-less two-axis MEMS micromirror (2mm diameter) and thus steers the beam in an ultrafast manner within a large optical deflection (10°) over the entire device bandwidth (1.2kHz). The MEMS mirror deflects the beam into a wide-angle lens that magnifies (about three times) the optical scan angles of the system. This magnification is linear and therefore results in an overall scan capability field of view of more than 30°. The power consumption of this system is less than 1mW and thus several orders of magnitude lower than that of galvanometer mirrors. The outgoing FSO beam from our MEMS beam-steering mechanism passes through autopoints and onto a receiving aperture (where it is efficiently coupled into a fiber collimator). With this fast and precise MEMS steering mechanism, we can switch the FSO from one rack to the next for reconfigurable networking. It also enables an autocorrection mechanism for fixing any misalignments (in real time). Figure 2. Photographs of the MEMS (microelectromechanical systems)-based proof-of-concept prototype assembly used to realize steerable FSO beams. In summary, we have designed the novel FireFly architecture for radically improving modern DC networks. Our vision includes unique characteristics, such as FSO-based inter-rack links and a fully flexible topology. Such features give rise to a number of algorithmic, networking, and system-level challenges that we are working to address. We have recently demonstrated the feasibility of our architecture with a proof-of-concept prototype for a MEMS-based steerable, small-form-factor FSO device. There are, however, various challenges that we need to address before we can realize commercialization of our architecture. In our current work we are thus building a small testbed for the FireFly architecture, which includes autoalignment through the use of galvanometers and MEMS steering technologies. We now plan to demonstrate the resilience of our FSO-link technologies against indoor effects, e.g., rack vibrations and temperature variations. This project was supported by the National Science Foundation award 1513866 (NeTS: Medium: Collaborative Research: Flexible All-Wireless Inter-Rack Fabric for Datacenters using Free-Space Optics) and represents a collaboration between faculty members, postdoctoral fellows, research associates, and graduate students at Pennsylvania State University, Stony Brook University, and Carnegie Mellon University. Electrical Engineering and Computer Science Pennsylvania State University Mohsen Kavehrad has been the W. L. Weiss Chair Professor of Electrical Engineering since 1997, and is the founding director of the Center for Information and Communications Technology Research. He has previously worked for Bell Laboratories and is a fellow of the IEEE. He is the author of more than 400 papers, several books and book chapters, and holds several patents. Department of Computer Science Stony Brook University Samir Das received his PhD in computer science from Georgia Institute of Technology. He previously studied at Jadavpur University, India, and the Indian Institute of Science. He has also worked briefly at the Indian Statistical Institute. He moved to Stony Brook in 2002 and was previously a faculty member at the University of Texas at San Antonio and then at the University of Cincinnati. Himanshu Gupta obtained his PhD in computer science from Stanford University in 1999 and his BTech from the Indian Institute of Technology in 1992. In his recent research he focuses on theoretical issues associated with wireless networking. In particular, he is interested in sensor networks and databases. His other research interests include database systems and theory, e.g., materialized views, (multiple) query optimization, and data analysis. Jon Longtin joined the mechanical engineering faculty in 1996. He is the author of more than 130 technical research publications, including a number of book chapters. He also holds six issued and three pending US patents. His expertise is in the thermal sciences, with a focus on the development of laser-based optical techniques for the measurement of temperature, concentration, and thermal properties. He is also interested in the use of ultrafast lasers for precision material processing and micromachining, and the development of sensors for harsh environments (e.g., direct-write thermal spray technology). He has been the recipient of a Japan Society for the Promotion of Science postdoctoral fellowship, the National Science Foundation's Faculty Early Career Development award and the Presidential Early Career Award for Scientists and Engineers, and the Stony Brook Excellence in Teaching award. He is a registered professional engineer in New York State. School of Computer Science Carnegie Mellon University Vyas Sekar is an assistant professor in the Electrical and Computer Engineering department. He received his PhD from Carnegie Mellon University in 2010 and earned his bachelor's degree from the Indian Institute of Technology Madras (during which he was awarded the President of India Gold Medal). His research interests lie at the intersection of networking, security, and systems. He has also received a number of best paper awards, e.g., at the Association for Computing Machinery's SIGCOMM, CoNext, and Multimedia conferences.

Khan S.H.,Wayne State University | Matei G.,Wayne State University | Patil S.,Indian Institute of Science | Hoffmann P.M.,Wayne State University
Physical Review Letters | Year: 2010

Mechanical properties of nanoconfined water layers are still poorly understood and continue to create controversy, despite their importance for biology and nanotechnology. We report on dynamic nanomechanical measurements of water films compressed to a few single molecular layers. We show that the mechanical properties of nanoconfined water layers change significantly with their dynamic state. In particular, we observed a sharp transition from viscous to elastic response even at extremely slow compression rates, indicating that mechanical relaxation times increase dramatically once water is compressed to less than 3-4 molecular layers. © 2010 The American Physical Society.

Mondal S.,Indian Association for The Cultivation of Science | Sen D.,Indian Institute of Science | Sengupta K.,Indian Association for The Cultivation of Science | Shankar R.,Chennai Mathematical Institute
Physical Review Letters | Year: 2010

We study the transport properties of the Dirac fermions with a Fermi velocity vF on the surface of a topological insulator across a ferromagnetic strip providing an exchange field J over a region of width d. We show that the conductance of such a junction, in the clean limit and at low temperature, changes from oscillatory to a monotonically decreasing function of d beyond a critical J. This leads to the possible realization of a magnetic switch using these junctions. We also study the conductance of these Dirac fermions across a potential barrier of width d and potential V0 in the presence of such a ferromagnetic strip and show that beyond a critical J, the criteria of conductance maxima changes from χ=eV0d/□vF=nπ to χ=(n+1/2)π for integer n. We point out that these novel phenomena have no analogs in graphene and suggest experiments which can probe them. © 2010 The American Physical Society.

Pradhan N.,Indian Association for The Cultivation of Science | Sarma D.D.,Indian Institute of Science
Journal of Physical Chemistry Letters | Year: 2011

Insertion of just a few impurity atoms in a host semiconductor nanocrystal can drastically alter its phase, shape, and physical properties. Such doped nanomaterials now constitute an important class of optical materials that can provide efficient, stable, and tunable dopant emission in visible and NIR spectral windows. Selecting proper dopants and inserting them in appropriate hosts can generate many new series of such doped nanocrystals with several unique and attractive properties in order to meet current challenges in the versatile field of luminescent materials. However, the synthesis of such doped nanomaterials with a specific dopant in a predetermined host at a desired site leading to targeted optical properties requires fundamental understanding of both the doping process as well as the resulting photophysical properties. Summarizing up to date literature reports, in this Perspective we discuss important advances in synthesis methods and in-depth understanding of the optical properties, with an emphasis on the most widely investigated Mn-doped semiconductor nanocrystals. © 2011 American Chemical Society.

Jose D.,Indian Institute of Science | Datta A.,Indian Association for The Cultivation of Science
Journal of Physical Chemistry C | Year: 2012

Silicene, the all Si analogue of graphene is structurally different due to the presence of buckling distortions in the individual six membered rings. The sufficiently strong coupling between the unoccupied molecular orbitals (UMOs) with occupied molecular orbitals (OMOs) leads to pseudo-Jahn-Teller distortion (PJT) and the characteristic buckling in silicenes. σ-π separation analyses reveal that the σ-backbone gets stabilized, whereas the π-backbone is destabilized due to buckling. However, the stabilization of puckering σ-backbone overwhelms the π-backbone destabilization. This is exactly opposite to that of graphene. The cations like Li+ can suppress the PJT distortions resulting in a planar structure. This leads to opening of band gap (∼1.62 eV). Si substituted benzenes binds more strongly with Li+ than benzene. The mutual competition/synergy between the orbital interactions of the ring with the cation and the π-charge density across the surface of molecule governs the stability of these complexes. © 2012 American Chemical Society.

Chatterjee S.,Indian Institute of Science | Godbole R.M.,Indian Institute of Science | Gupta S.,Tata Institute of Fundamental Research
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We argue that known systematics of hadron cross sections may cause different particles to freeze out of the fireball produced in heavy-ion collisions at different times. We find that a simple model with two freezeout points is a better description of data than that with a single freezeout, while still remaining predictive. The resulting fits seem to present constraints on the late stage evolution of the fireball, including the tantalizing possibility that the QCD chiral transition influences the yields at S=2700GeV and the QCD critical point those at S=17.3GeV. © 2013 Elsevier B.V.

Jissy A.K.,Indian Institute of Science | Datta A.,Indian Association for The Cultivation of Science
Journal of Physical Chemistry Letters | Year: 2013

Recently, inorganic double-helical structures based on simple lithium and phosphorus salts have been demonstrated. We have analyzed the nature of bonding in these double helices of LinPn (n = 7-9). Similar to DNA, noncovalent interactions and cooperativity play an important role in stabilizing the inorganic double helices. Cooperativity imparts an additional stabilization of 4.5 to 10.1 kcal/mol per Li-P pair. In addition, the ionicity of Li-P units further augments the stability of these inorganic double-helix structures in contrast with the canonical base pairs in DNA, where noncovalent interactions determine the duplex stability. Unwinding is shown to be unfavorable, and cleavage of a few edge Li-P bonds leads to spontaneous self-healing into the intact double-helix tract. © 2013 American Chemical Society.

Anirudhan A.,Indian Institute of Science | Anirudhan A.,National Institute of Technology Calicut | Anirudhan A.,Sree Chitra Thirunal Institute of Medical Sciences and Technology | Narayanan R.,Indian Institute of Science
Journal of Neuroscience | Year: 2015

An open question within the Bienenstock-Cooper-Munro theory for synaptic modification concerns the specific mechanism that is responsible for regulating the sliding modification threshold (SMT). In this conductance-based modeling study on hippocampal pyramidal neurons, we quantitatively assessed the impact of seven ion channels (R- and T-type calcium, fast sodium, delayed rectifier,A-type, and small-conductance calcium-activated (SK) potassium and HCN) and two receptors (AMPAR and NMDAR) on a calcium-dependent Bienenstock-Cooper-Munro-like plasticity rule. Our analysis with R- and T-type calcium channels revealed that differences in their activation-inactivation profiles resulted in differential impacts on how they altered the SMT. Further, we found that the impact of SK channels on the SMT critically depended on the voltage dependence and kinetics of the calcium sources with which they interacted. Next, we considered interactions among all the seven channels and the two receptors through global sensitivity analysis on 11 model parameters. We constructed 20,000 models through uniform randomization of these parameters and found 360 valid models based on experimental constraints on their plasticity profiles. Analyzing these 360 models, we found that similar plasticity profiles could emerge with several nonunique parametric combinations and that parameters exhibited weak pairwise correlations. Finally, we used seven sets of virtual knock-outs on these 360 models and found that the impact of different channels on the SMT was variable and differential. These results suggest that there are several nonunique routes to regulate the SMT, and call for a systematic analysis of the variability and state dependence of the mechanisms underlying metaplasticity during behavior and pathology. ©2015 the authors.

Reddy A.L.M.,Rice University | Gowda S.R.,Rice University | Shaijumon M.M.,Indian Institute of Science | Ajayan P.M.,Rice University
Advanced Materials | Year: 2012

Materials engineering plays a key role in the field of energy storage. In particular, engineering materials at the nanoscale offers unique properties resulting in high performance electrodes and electrolytes in various energy storage devices. Consequently, considerable efforts have been made in recent years to fulfill the future requirements of electrochemical energy storage using these advanced materials. Various multi-functional hybrid nanostructured materials are currently being studied to improve energy and power densities of next generation storage devices. This review describes some of the recent progress in the synthesis of different types of hybrid nanostructures using template assisted and non-template based methods. The potential applications and recent research efforts to utilize these hybrid nanostructures to enhance the electrochemical energy storage properties of Li-ion battery and supercapacitor are discussed. This review also briefly outlines some of the recent progress and new approaches being explored in the techniques of fabrication of 3D battery structures using hybrid nanoarchitectures. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Raju T.S.,Temple City Institute of Technology and Engineering | Panigrahi P.K.,Indian Institute of Science
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We analytically explore a wide class of optical similariton solutions to the nonlinear Schrödinger equation appropriately modified to model beam propagation in a tapered, graded-index nonlinear-fiber amplifier with an external source. Under certain physical conditions, we reduce the coupled nonlinear Schrödinger equations to a single-wave equation that aptly describes similariton propagation through asymmetric twin-core fiber amplifiers. The asymmetric twin-core fiber is composed of two adjoining, closely spaced, single-mode fibers in which the active one is a tapered, graded-index nonlinear-fiber and the passive one is a step-index fiber. We obtain these self-similar waves for different choices of tapered index profile, using a Möbius transformation. Our procedure is applicable for both self-focusing and self-defocusing nonlinearities. © 2011 American Physical Society.

Ravikant V.,Indian Institute of Science | Wu F.-Y.,CAS Institute of Geology and Geophysics | Ji W.-Q.,CAS Institute of Geology and Geophysics
Earth and Planetary Science Letters | Year: 2011

The Subhimalaya of NW India exposes a well developed marine to continental foreland sequence preserving sediments shed from the tectonically evolving Cenozoic Himalayan orogen. Detrital zircon U-Pb ages and their Hf isotopic compositions, of seven samples, were analyzed from the Subathu sub-basin foreland formations to constrain sediment provenance. The detrital zircon U-Pb age spectra yielded a similar pattern, for all foreland formations, with major peaks clustered at ~. 500-650. Ma, 900-1000. Ma and ~. 2500. Ma, corresponding to (indistinguishable) Tethyan Himalaya and Higher Himalayan Crystalline sources and those at ~. 1800-1900. Ma corresponding to lower a Lesser Himalayan arc source. Comparison of the foreland detrital zircon U-Pb age spectra with Himalayan lithotectonic source units, in conjunction with their Hf isotopes and previously determined sediment petrography and age constraints, suggest that the sediments to the flysch marine Subathu Formation (~65 to >41. Ma) were sourced from a positive-relief area of the Tethyan Himalaya mixed with detritus from lower Lesser Himalaya and additional cratonic northern Indian Precambrian rocks. No Cretaceous to Eocene-aged detrital zircons, contributed by eroding Ladakh batholith north of the Indus Tsangpo suture zone, were recorded in the Palaeogene-aged foreland samples. The younger synorogenic continental Dagshai Formation (<30 to <22. Ma) sediments were sourced from the very low-grade Tethyan Himalaya, whereas the alluvial-facies Kasauli Formation (<22 to 13. Ma) began to receive sediments additionally from erosion of the medium-grade metamorphic rocks of the Higher Himalayan Crystalline and the lower Lesser Himalaya. The Lower Siwalik Formation sediments (~13-11.5. Ma) were derived from the low-grade rocks of the Tethyan Himalaya, both the upper and lower Lesser Himalaya and additionally from the eroding high-grade migmatitic gneisses of the Higher Himalayan Crystalline. Thus, from the similar detrital zircon age spectra of the foreland formations, we infer that differences in the continental sediment detritus into the foreland basin reflect a straightforward sediment mixture of variable proportions from fixed Himalayan lithotectonic sources which progressively shifted towards the foreland with development of the orogen. © 2011 Elsevier B.V.

Choudhuri A.R.,Indian Institute of Science | Choudhuri A.R.,Japan National Astronomical Observatory | Karak B.B.,Indian Institute of Science
Physical Review Letters | Year: 2012

One of the most striking aspects of the 11-year sunspot cycle is that there have been times in the past when some cycles went missing, a most well-known example of this being the Maunder minimum during 1645-1715. Analyses of cosmogenic isotopes (C14 and Be10) indicated that there were about 27 grand minima in the last 11000yrs, implying that about 2.7% of the solar cycles had conditions appropriate for forcing the Sun into grand minima. We address the question of how grand minima are produced and specifically calculate the frequency of occurrence of grand minima from a theoretical dynamo model. We assume that fluctuations in the poloidal field generation mechanism and in the meridional circulation produce irregularities of sunspot cycles. Taking these fluctuations to be Gaussian and estimating the values of important parameters from the data of the last 28 solar cycles, we show from our flux transport dynamo model that about 1-4% of the sunspot cycles may have conditions suitable for inducing grand minima. © 2012 American Physical Society.

Jose D.,Indian Institute of Science | Datta A.,Indian Institute of Science | Datta A.,Indian Association for The Cultivation of Science
Angewandte Chemie - International Edition | Year: 2012

Successfully tunneled: The rapid and temperature-independent intramolecular proton transfer in thiotropolone occurs entirely through quantum mechanical tunneling (see picture). For tropolone, tunneling across a smaller yet broader barrier leads to a slower rate of proton transfer for temperatures smaller than 240 K. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Banerjee D.,Indian Institute of Science | Williams J.C.,University of North Texas | Williams J.C.,Ohio State University
Acta Materialia | Year: 2013

The basic framework and - conceptual understanding of the metallurgy of Ti alloys is strong and this has enabled the use of titanium and its alloys in safety-critical structures such as those in aircraft and aircraft engines. Nevertheless, a focus on cost-effectiveness and the compression of product development time by effectively integrating design with manufacturing in these applications, as well as those emerging in bioengineering, has driven research in recent decades towards a greater predictive capability through the use of computational materials engineering tools. Therefore this paper focuses on the complexity and variety of fundamental phenomena in this material system with a focus on phase transformations and mechanical behaviour in order to delineate the challenges that lie ahead in achieving these goals. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Jissy A.K.,Indian Institute of Science | Datta A.,Indian Association for The Cultivation of Science
ChemPhysChem | Year: 2012

The structure and electronic properties of guanine oligomers and π stacks of guanine quartets (G-quartets) with circulene are investigated under an external field through first-principles calculations. An electric field induces nonplanarity in the guanine aggregates and also leads to an increase in the H-bond distances. The calculations reveal that the binding energy of the circulenes with G-quartets increases on application of an electric field along the stacking direction. The HOMO-LUMO gap decreases substantially under the influence of an external field. The contribution of a simple dipole-dipole interaction to the stability of the stacked system is also analyzed. The electric field along the perpendicular axis increases the dipole moments of the guanine dimer, trimer, and quartet. Such an increase in the dipole moment facilitates stacking with circulenes. The stability of G-quartet-circulene π stacks depends on the phase of the dipole moment (in-phase or out-of-phase) induced by an external electric field. The stability of stacks of bowl-shaped circulenes with G-quartets depends on the direction of the applied field. Making a stack: An external electric field helps stacking of guanine quartets with disklike molecules such as circulenes to facilitate molecular recognition by DNA quadruplexes (see picture). The stability of stacks of bowl-shaped circulenes with G-quartets depends on the direction of the applied field. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Das U.,Indian Institute of Science | Mukhopadhyay B.,Indian Institute of Science | Rao A.R.,Tata Institute of Fundamental Research
Astrophysical Journal Letters | Year: 2013

Several recently discovered peculiar Type Ia supernovae seem to demand an altogether new formation theory that might help explain the puzzling dissimilarities between them and the standard Type Ia supernovae. The most striking aspect of the observational analysis is the necessity of invoking super-Chandrasekhar white dwarfs having masses ∼2.1-2.8 M⊙, M⊙ being the mass of Sun, as their most probable progenitors. Strongly magnetized white dwarfs having super-Chandrasekhar masses have already been established as potential candidates for the progenitors of peculiar Type Ia supernovae. Owing to the Landau quantization of the underlying electron degenerate gas, theoretical results yielded the observationally inferred mass range. Here, we sketch a possible evolutionary scenario by which super-Chandrasekhar white dwarfs could be formed by accretion on to a commonly observed magnetized white dwarf, invoking the phenomenon of flux freezing. This opens multiple possible evolution scenarios ending in supernova explosions of super-Chandrasekhar white dwarfs having masses within the range stated above. We point out that our proposal has observational support, such as the recent discovery of a large number of magnetized white dwarfs by the Sloan Digital Sky Survey. © 2013. The American Astronomical Society. All rights reserved.

Roy K.,Indian Institute of Science | Padmanabhan M.,Indian Institute of Science | Goswami S.,Indian Institute of Science | Goswami S.,Technical University of Delft | And 5 more authors.
Nature Nanotechnology | Year: 2013

Combining the electronic properties of graphene and molybdenum disulphide (MoS 2) in hybrid heterostructures offers the possibility to create devices with various functionalities. Electronic logic and memory devices have already been constructed from graphene-MoS 2 hybrids, but they do not make use of the photosensitivity of MoS 2, which arises from its optical-range bandgap. Here, we demonstrate that graphene-on-MoS 2 binary heterostructures display remarkable dual optoelectronic functionality, including highly sensitive photodetection and gate-tunable persistent photoconductivity. The responsivity of the hybrids was found to be nearly 1 × 10 10 A W -1 at 130 K and 5 × 10 8 A W -1 at room temperature, making them the most sensitive graphene-based photodetectors. When subjected to time-dependent photoillumination, the hybrids could also function as a rewritable optoelectronic switch or memory, where the persistent state shows almost no relaxation or decay within experimental timescales, indicating near-perfect charge retention. These effects can be quantitatively explained by gate-tunable charge exchange between the graphene and MoS 2 layers, and may lead to new graphene-based optoelectronic devices that are naturally scalable for large-area applications at room temperature.

Best Institute And Research Center and Indian Institute of Science | Date: 2012-02-29

The present invention provides a laparoscopic apparatus having an elongated barrel connected to a handle case with a fixed handle and a movable handle. A rotatable conduit is connected to a rotatable wheel with a movable rod disposed inside the elongated barrel, which is operable by the rotatable wheel. An end-effector with wrist-like movement is connected to an articulation assembly of the fixed handle in conjunction with a universal joint. The laparoscopic apparatus of the present invention with the end-effector assembly provides a wrist-like lateral movement. The laparoscopic surgical apparatus of the present invention has an improved articulation and an extra degree of freedom, while retaining its existing surgical functions.

News Article | December 27, 2016

The Biophysical Society has announced the winners of its international travel grants to attend the Biophysical Society's 61st Annual Meeting in New Orleans, February 11-15, 2017. The purpose of these awards is to foster and initiate further interaction between American biophysicists and scientists working in countries experiencing financial difficulties. Recipients of this competitive award are chosen based on scientific merit and their proposed presentation at the meeting. They will be honored at a reception on Sunday, February 12 at the Ernest N. Morial Convention Center. The 2017 recipients of the International Travel Award, along with their institutional affiliation and abstract title, are listed below. Ana F. Guedes, Institute of Molecular Medicine, Portugal, ATOMIC FORCE MICROSCOPY AS A TOOL TO EVALUATE THE RISK OF CARDIOVASCULAR DISEASES IN PATIENTS. Karishma Bhasne Mohali, Indian Institute of Science Education and Research (IISER), A TALE OF TWO AMYLOIDOGENIC INTRINSICALLY DISORDERED PROTEINS: INTERPLAY OF TAU AND α-SYNUCLEIN. Chan Cao, East China University of Science and Technology, DIRECT IDENTIFICATION OF ADENINE, THYMINE, CYTOSINE AND GUANINE USING AEROLYSIN NANOPORE. Venkata Reddy Chirasani, Indian Institute of Technology Madras, LIPID TRANSFER MECHANISM OF CETP BETWEEN HDL AND LDL: A COARSEGRAINED SIMULATION STUDY. Assaf Elazar, Weizmann Institute of Science, Israel, DECIPHERING MEMBRANE PROTEIN ENERGETICS USING DEEP SEQUENCING; TOWARDS ROBUST DESIGN AND STRUCTURE PREDICTION OF MEMBRANE PROTEINS. Manuela Gabriel, University of Buenos Aires, Argentina, 3D ORBITAL TRACKING OF SINGLE GOLD NANOPARTICLES: A NEW APPROACH TO STUDY VESICLE TRAFFICKING IN CHROMAFFIN CELLS. Farah Haque National Centre for Biological Sciences, India, A NEW HUMANIZED MOUSE MODEL FOR STUDYING INHERITED CARDIOMYOPATHIC MUTATIONS IN THE MYH7 GENE. Stephanie Heusser, Stockholm University, Switzerland, STRUCTURAL AND FUNCTIONAL EVIDENCE FOR MULTI-SITE ALLOSTERY MEDIATED BY GENERAL ANESTHETICS IN A MODEL LIGAND-GATED ION CHANNEL. Amir Irani, Massey University, New Zealand, HOMOGALACTURONANS ILLUMINATE THE ROLE OF COUNTERION CONDENSATION IN POLYELECTROLYTE TRANSPORT. Olfat Malak, University of Nantes, France, HIV-TAT INDUCES A DECREASE IN IKR AND IKS VIA REDUCTION IN PHOSPHATIDYLINOSITOL-(4,5)-BISPHOSPHATE AVAILABILITY. CONFORMATIONAL TRANSITION AND ASSEMBLY OF E.COLI CYTOLYSIN A PORE FORMING TOXIN BY SINGLE MOLECULE FLUORESCENCE. Sabrina Sharmin, Shizuoka University, Japan, EFFECTS OF LIPID COMPOSITIONS ON THE ENTRY OF CELL PENETRATING PEPTIDE OLIGOARGININE INTO SINGLE VESICLES. Xin Shi, East China University of Science and Technology, DIRECT OBSERVATION OF SINGLE BIOPOLYMER FOLDING AND UNFOLDING PROCESS BY SOLIDSTATE NANOPORE. Omar Alijevic, University of Lausanne, Switzerland, ANALYSIS OF GATING OF ACID-SENSING ION CHANNELS (ASICS) UNDER RAPID AND SLOW PH CHANGES. Swapna Bera, Bose Institute, India, BIOPHYSICAL INSIGHTS INTO THE MEMBRANE INTERACTION OF THE CORE AMYLOID-FORMING Aβ40 FRAGMENT K16-K28 AND ITS ROLE IN THE PATHOGENESIS OF ALZHEIMER'S DISEASE. Anais Cassaignau, University College London, United Kingdom, STRUCTURAL INVESTIGATION OF AN IMMUNOGLOBULIN DOMAIN ON THE RIBOSOME USING NMR SPECTROSCOPY. Bappaditya Chandra, Tata Institute of Fundamental Research, India, SECONDARY STRUCTURE FLIPPING CONNECTED TO SALT-BRIDGE FORMATION CONVERTS TOXIC AMYLOID-β40 OLIGOMERS TO FIBRILS. Gayathri Narasimhan, Cinvestav, Mexico, ANTIHYPERTROPHIC EFFECTS OF DIAZOXIDE INVOLVES CHANGES IN MIR-132 EXPRESSION IN ADULT RAT CARDIOMYCYTES. Giulia Paci, European Molecular Biology Laboratory, Germany, FOLLOWING A GIANT'S FOOTSTEPS: SINGLE-PARTICLE AND SUPER-RESOLUTION APPROACHES TO DECIPHER THE NUCLEAR TRANSPORT OF HEPATITIS B VIRUS CAPSIDS. Bizhan Sharopov, Bogomoletz Institute of Physiology National Academy of Sciences of Ukraine, DISSECTING LOCAL AND SYSTEMIC EFFECTS OF TRPV1 ON BLADDER CONTRACTILITY IN DIABETES. Chao Sun, East China Normal University, FUNCTION OF BACTERIORUBERIN IN ARCHAERHODOPSIN 4, FROM EXPRESSION TO CHARACTERIZATION. Matthew Batchelor, University of Leeds, United Kingdom STRUCTURAL DYNAMICS IN THE MYOSIN 7A SINGLE α-HELIX DOMAIN. Daniel Havelka, Czech Academy of Sciences, MICROVOLUME DIELECTRIC SPECTROSCOPY AND MOLECULAR DYNAMICS OF AMINO ACIDS. Ivan Kadurin, University College London, United Kingdom, INVESTIGATION OF THE PROTEOLYTIC CLEAVAGE OF α2δ SUBUNITS: A MECHANISTIC SWITCH FROM NHIBITION TO ACTIVATION OF VOLTAGE-GATED CALCIUM CHANNELS? Linlin Ma, University of Queensland, Australia, NOVEL HUMAN EAG CHANNEL ANTAGONISTS FROM SPIDER VENOMS. Ivana Malvacio, University of Cagliari, Italy, MOLECULAR INSIGHTS ON THE RECOGNITION OF SUBSTRATES BY THE PROMISCUOUS EFFLUX PUMP ACRB. Cristina Moreno Vadillo, Cardiovascular Research Institute Maastricht, Netherlands, RESTORING DEFECTIVE CAMP-DEPENDENT UPREGULATION IN LONG-QT SYNDROME TYPE-1 THROUGH INTERVENTIONS THAT PROMOTE IKS CHANNEL OPENING. Melanie Paillard, Claude Bernard University Lyon 1, France, TISSUE-SPECIFIC MITOCHONDRIAL DECODING OF CYTOPLASMIC CA2+ SIGNALS IS CONTROLLED BY THE STOICHIOMETRY OF MICU1/2 AND MCU. Mohammed Mostafizur Rahman, Institute for Stem Cell Biology and Regenerative Medicine, India, STRESS-INDUCED DIFFERENTIAL REGULATION LEADS TO DECOUPLING OF THE ACTIVITY BETWEEN MPFC AND AMYGDALA. Marcin Wolny, University of Leeds, United Kingdom, DESIGN AND CHARACTERIZATION OF LONG AND STABLE DE NOVO SINGLE α-HELIX DOMAINS. Elvis Pandzic, University of New South Wales, Australia, VELOCITY LANDSCAPES RESOLVE MULTIPLE DYNAMICAL POPULATIONS FROM FLUORESCENCE IMAGE TIME SERIES. The Biophysical Society, founded in 1958, is a professional, scientific Society established to encourage development and dissemination of knowledge in biophysics. The Society promotes growth in this expanding field through its annual meeting, monthly journal, and committee and outreach activities. Its 9000 members are located throughout the U.S. and the world, where they teach and conduct research in colleges, universities, laboratories, government agencies, and industry. For more information on these awards, the Society, or the 2017 Annual Meeting, visit http://www.

Home > Press > Rice expands graphene repertoire with MRI contrast agent: Metal-free fluorinated graphene shows no signs of toxicity in cell culture tests Abstract: Graphene, the atomically thin sheets of carbon that materials scientists are hoping to use for everything from nanoelectronics and aircraft de-icers to batteries and bone implants, may also find use as contrast agents for magnetic resonance imaging (MRI), according to new research from Rice University. "They have a lot of advantages compared with conventionally available contrast agents," Rice researcher Sruthi Radhakrishnan said of the graphene-based quantum dots she has studied for the past two years. "Virtually all of the widely used contrast agents contain toxic metals, but our material has no metal. It's just carbon, hydrogen, oxygen and fluorine, and in all of our tests so far it has shown no signs of toxicity." The initial findings for Rice's nanoparticles -- disks of graphene that are decorated with fluorine atoms and simply organic molecules that make them magnetic -- are described in a new paper in the journal Particle and Particle Systems Characterization. Pulickel Ajayan, the Rice materials scientist who is directing the work, said the fluorinated graphene oxide quantum dots could be particularly useful as MRI contrast agents because they could be targeted to specific kinds of tissues. "There are tried-and-true methods for attaching biomarkers to carbon nanoparticles, so one could easily envision using these quantum dots to develop tissue-specific contrast agents," Ajayan said. "For example, this method could be used to selectively target specific types of cancer or brain lesions caused by Alzheimer's disease. That kind of specificity isn't available with today's contrast agents." MRI scanners make images of the body's internal structures using strong magnetic fields and radio waves. As diagnostic tests, MRIs often provide greater detail than X-rays without the harmful radiation, and as a result, MRI usage has risen sharply over the past decade. More than 30 million MRIs are performed annually in the U.S. Radhakrishnan said her work began in 2014 after Ajayan's research team found that adding fluorine to either graphite or graphene caused the materials to show up well on MRI scans. All materials are influenced by magnetic fields, including animal tissues. In MRI scanners, a powerful magnetic field causes individual atoms throughout the body to become magnetically aligned. A pulse of radio energy is used to disrupt this alignment, and the machine measures how long it takes for the atoms in different parts of the body to become realigned. Based on these measures, the scanner can build up a detailed image of the body's internal structures. MRI contrast agents shorten the amount of time it takes for tissues to realign and significantly improve the resolution of MRI scans. Almost all commercially available contrast agents are made from toxic metals like gadolinium, iron or manganese. "We worked with a team from MD Anderson Cancer Center to assess the cytocompatibility of fluorinated graphene oxide quantum dots," Radhakrishnan said. "We used a test that measures the metabolic activity of cell cultures and detects toxicity as a drop in metabolic activity. We incubated quantum dots in kidney cell cultures for up to three days and found no significant cell death in the cultures, even at the highest concentrations." The fluorinated graphene oxide quantum dots Radhakrishnan studies can be made in less than a day, but she spent two years perfecting the recipe for them. She begins with micron-sized sheets of graphene that have been fluorinated and oxidized. When these are added to a solvent and stirred for several hours, they break into smaller pieces. Making the material smaller is not difficult, but the process for making small particles with the appropriate magnetic properties is exacting. Radhakrishnan said there was no "eureka moment" in which she suddenly achieved the right results by stumbling on the best formula. Rather, the project was marked by incremental improvements through dozens of minor alterations. "It required a lot of optimization," she said. "The recipe matters a lot." Radhakrishnan said she plans to continue studying the material and hopes to eventually have a hand in proving that it is safe and effective for clinical MRI tests. "I would like to see it applied commercially in clinical ways because it has a lot of advantages compared with conventionally available agents," she said. Additional co-authors include Parambath Sudeep and Chandra Tiwary, both of Rice; Atanu Samanta and Abhishek Singh, both of the Indian Institute of Science at Bangalore; Kiersten Maldonado and Sendurai Mani, both of MD Anderson; and Ghanashyam Acharya of Baylor College of Medicine. The research was supported by the Hamill Foundation through a Hamill Innovation Award to Rice's Institute of Biosciences and Bioengineering, the Air Force Office of Scientific Research, the Indian Institute of Science at Bangalore's Supercomputing Education Research Centre and India's Indo-US Science and Technology Forum. About Rice University Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to . Follow Rice News and Media Relations on Twitter @RiceUNews. If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

News Article | December 16, 2016

Microelectromechanical systems, or MEMS, are tiny machines fabricated using equipment and processes developed for the production of electronic chips and devices. They’ve found a wide variety of applications in today’s consumer electronics, but their moving parts can wear out over time as a result of friction. A new approach developed by researchers at MIT could offer a new way of making movable parts with no solid connections between the pieces, potentially eliminating a major source of wear and failure. The new system uses a layer of liquid droplets to support a tiny, movable platform, which essentially floats on top of the droplets. The droplets can be water or some other fluid, and the precise movements of the platform can be controlled electrically, through a system that can alter the dimensions of the droplets to raise, lower, and tilt the platform. The new findings are reported in a paper in Applied Physics Letters, co-authored by Daniel Preston, an MIT graduate student; Evelyn Wang, the Gail E. Kendall Associate Professor of Mechanical Engineering; and five others. Preston explains that the new system could be used to make devices such as stages for microscope specimens. The focus of the microscope could be controlled by raising or lowering the stage, which would involve changing the shapes of supporting liquid droplets. The system works by altering the way the droplets interact with the surface below them, governed by a characteristic known as the contact angle. This angle is a measure of how steep the edge of the droplet is at the point where it meets the surface. On hydrophilic, or water-attracting, surfaces, droplets spread out nearly flat, producing a very small contact angle, while hydrophobic, or water-repelling, surfaces cause droplets to be nearly spherical, barely touching the surface, with very large contact angles. On certain kinds of dielectric surfaces, these qualities can be “tuned” across that whole range by simply varying a voltage applied to the surface. As the surface gets more hydrophobic and the droplets get rounder, their tops rise farther from the surface, thus raising the platform — in these tests, a thin sheet of copper — that floats on them. By selectively changing different droplets by different amounts, the platform can also be selectively tilted. This could be used, for example, to change the angle of a mirrored surface in order to aim a laser beam, Preston says. “There are a lot of experiments that use lasers, that could really benefit from a way to make these small-scale movements.” The new system could be used to make devices such as stages for microscope specimens. The focus of the microscope could be controlled by raising or lowering the stage, which would involve changing the shapes of supporting liquid droplets. (Image: Daniel Preston/Device Research Lab) In order to maintain the positioning of the droplets rather than letting them slide around, the team treated the underside of the floating platform. They made the overall surface hydrophobic, but with small circles of hydrophilic material. That way, all the droplets are securely “pinned” to those water-attracting surfaces, keeping the platform securely in position. In the group’s initial test device, the vertical positioning can be controlled to within a precision of 10 microns, or millionths of a meter, over a range of motion of 130 microns. MEMS devices, Preston says, “often fail when there’s a solid-solid contact that wears out, or just gets stuck. At these very small scales, things break down easily.” While the basic technology behind the alteration of droplet shapes on a surface is not a new idea, Preston says, “nobody has used it to move a stage, without any solid-solid contact. The real innovation here is being able to move a stage up and down, and change its angle, without any solid material connections.” In principle, it would be possible to use a large array of electrodes that could be adjusted to move a platform across a surface in precise ways, in addition to up and down. For example, it could be used for “lab on a chip” applications, where a biological sample could be mounted on the platform and then moved around from one test site to another on the microchip. He says the system is relatively simple to implement and that it would be possible to develop it for specific real-world application fairly rapidly. “It depends how motivated people are,” he says. “But I don’t see any huge barriers to large-scale use. I think it could be done within a year.” “Controlled movements of a stage in microscale are difficult, because the miniature versions of the familiar motors and gear mechanisms do not exist, and if they existed, they would be too weak and frictional, respectively,” says Chang-Jin Kim, a professor of mechanical and aerospace engineering at the University of California at Los Angeles, who was not involved in this research. “Since this challenge is rather fundamental, it is only logical (albeit exotic) to use liquid droplets as a mechanical element,” he says. “There are numerous questions remaining before this stage becomes practical, but this is a good start proving the main design concept.” “This approach is simpler and hence is expected to provide a significant cost benefit over existing techniques in practical applications,” says Prosenjit Sen, an assistant professor at the Centre for Nano Science and Engineering at the Indian Institute of Science, who also was not involved in this work. “The use of droplet supports additionally provides some degree of vibration isolation, which is not possible in all-solid stages.” The research team included MIT graduate students Ariel Anders and Yangying Zhu, Research Affiliate Banafsheh Barabadi, alumna Evelyn Tio ’14, and undergraduate student DingRan Dai. The work was supported by the Office of Naval Research and the National Science Foundation.

Anandhakumar S.,SRM University | Raichur A.M.,Indian Institute of Science
Acta Biomaterialia | Year: 2013

We demonstrate a nanoparticle loading protocol to develop a transparent, multifunctional polyelectrolyte multilayer film for externally activated drug and protein delivery. The composite film was designed by alternate adsorption of poly(allylamine hydrochloride) (PAH) and dextran sulfate (DS) on a glass substrate followed by nanoparticle synthesis through a polyol reduction method. The films showed a uniform distribution of spherical silver nanoparticles with an average diameter of 50 ± 20 nm, which increased to 80 ± 20 nm when the AgNO3 concentration was increased from 25 to 50 mM. The porous and supramolecular structure of the polyelectrolyte multilayer film was used to immobilize ciprofloxacin hydrochloride (CH) and bovine serum albumin (BSA) within the polymeric network of the film. When exposed to external triggers such as ultrasonication and laser light the loaded films were ruptured and released the loaded BSA and CH. The release of CH is faster than that of BSA due to a higher diffusion rate. Circular dichroism measurements confirmed that there was no significant change in the conformation of released BSA in comparison with native BSA. The fabricated films showed significant antibacterial activity against the bacterial pathogen Staphylococcus aureus. Applications envisioned for such drug-loaded films include drug and vaccine delivery through the transdermal route, antimicrobial or anti-inflammatory coatings on implants and drug-releasing coatings for stents. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Kusari S.,TU Dortmund | Singh S.,Indian Institute of Science | Jayabaskaran C.,Indian Institute of Science
Trends in Biotechnology | Year: 2014

Taxol® (generic name paclitaxel) represents one of the most clinically valuable natural products known to mankind in the recent past. More than two decades have elapsed since the notable discovery of the first Taxol®-producing endophytic fungus, which was followed by a plethora of reports on other endophytes possessing similar biosynthetic potential. However, industrial-scale Taxol® production using fungal endophytes, although seemingly promising, has not seen the light of the day. In this opinion article, we embark on the current state of knowledge on Taxol® biosynthesis focusing on the chemical ecology of its producers, and ask whether it is actually possible to produce Taxol® using endophyte biotechnology. The key problems that have prevented the exploitation of potent endophytic fungi by industrial bioprocesses for sustained production of Taxol® are discussed. © 2014 Elsevier Ltd.

Shukla J.,Indian Institute of Science | Gupta R.,Institute of Genomics and Integrative Biology | Thakur K.G.,Chandigarh Institute of Microbial Technology | Gokhale R.,Institute of Genomics and Integrative Biology | Gopal B.,Indian Institute of Science
Acta Crystallographica Section D: Biological Crystallography | Year: 2014

The host-pathogen interactions in Mycobacterium tuberculosis infection are significantly influenced by redox stimuli and alterations in the levels of secreted antigens. The extracytoplasmic function (ECF) σ factor σK governs the transcription of the serodominant antigens MPT70 and MPT83. The cellular levels of σK are regulated by the membrane-associated anti-σK (RskA) that localizes σK in an inactive complex. The crystal structure of M. tuberculosis σK in complex with the cytosolic domain of RskA (RskAcyto) revealed a disulfide bridge in the-35 promoter-interaction region of σK. Biochemical experiments reveal that the redox potential of the disulfide-forming cysteines in σK is consistent with its role as a sensor. The disulfide bond in σK influences the stability of the σK-RskAcyto complex but does not interfere with σK-promoter DNA interactions. It is noted that these disulfide-forming cysteines are conserved across homologues, suggesting that this could be a general mechanism for redox-sensitive transcription regulation. © 2014 International Union of Crystallography.

Dasgupta S.,Indian Institute of Science | Bose S.,Presidency University of India | Das K.,Bengal Engineering and Science University | Das K.,Hiroshima University
Precambrian Research | Year: 2013

We present possible tectonic models for two crustal domains of the Proterozoic Eastern Ghats Belt, India based on recent petrological, geophysical and geochronological data. Although both the domains presently expose deep crustal sections, they evolved in two distinct time segments of the Precambrian through accretion-collision processes. This is why we argue that no unique model can explain the complexities of the belt. The southern part of the belt evolved through subduction-dominated accretionary processes encompassing India, east Antarctica, Australia and Laurentia as part of supercontinent Columbia during the span of ca. 1.90-1.60. Ga. To the contrary, the central domain witnessed a prolonged accretion-collision history initiated at ca. 1.50. Ga and culminated at ca. 0.90. Ga with the formation of supercontinent Rodinia. The latter united cratonic India with east Antarctica as a separate continent Enderbia that existed until about ca. 0.50. Ga. The pre-1.50. Ga history of this domain is ambiguous at the present state of knowledge. The northern domain has a much younger (ca. 0.90-0.50. Ga) tectonothermal history which is unrelated to either of the studied domains. The present models explain the reported petrotectonic processes including the ultra high temperature metamorphism in both the domains. The episodic growth of the Eastern Ghats Belt matches with Proterozoic supercontinent cycles. © 2012 Elsevier B.V.

Visweswariah S.S.,Indian Institute of Science | Busby S.J.W.,University of Birmingham
Trends in Microbiology | Year: 2015

Many bacterial transcription factors do not behave as per the textbook operon model. We draw on whole genome work, as well as reported diversity across different bacteria, to argue that transcription factors may have evolved from nucleoid-associated proteins. This view would explain a large amount of recent data gleaned from high-throughput sequencing and bioinformatic analyses. © 2015 Elsevier Ltd.

Kusari S.,TU Dortmund | Singh S.,Indian Institute of Science | Jayabaskaran C.,Indian Institute of Science
Trends in Biotechnology | Year: 2014

The potential of endophytes, particularly endophytic fungi, capable of demonstrating desirable functional traits worth exploitation using red biotechnology is well established. However, these discoveries have not yet translated into industrial bioprocesses for commercial production of biopharmaceuticals using fungal endophytes. Here, we define the current challenges in transforming curiosity driven discoveries into industrial scale endophyte biotechnology. The possible practical, feasible, and sustainable strategies that can lead to harnessing fungal endophyte-mediated pharmaceutical products are discussed. © 2014 Elsevier Ltd.

News Article | March 1, 2017

On the evening of Thursday 16 February, residents in the south-east part of Bangalore noticed huge plumes of smoke rising into the sky. The smoke was coming from the middle of Bellandur Lake – the biggest lake in the city at a little over 890 acres. They realised the seemingly impossible had happened: the lake had caught fire. Even fire fighters wondered how a blaze in water could be put out. The fire in the lake burned for 12 hours and left behind a sinister black patch in the centre, according to some eye-witness accounts. This is the new story of Bangalore – state capital, India’s Silicon Valley, and once upon a time, the “city of lakes”. The reasons why these lakes are able to catch fire begin to explain why scientists at the influential Indian Institute of Science believe Bangalore will be “unliveable” in a few years’ time. A lethal mix of factors create an environment that merely requires the slightest of triggers for lakes to go up in flames. Untreated effluents pour into the waters from the many industries and homes on its banks, illegal waste disposal takes place on a large scale – often including rubbish which is set on fire – and invasive weeds cover large swathes of the lake in a thick green canopy. The latest incident is not the first time the lake has caught fire; it happened in May 2015. A few days later, it was in the news again for being covered in snow-like froth, which began to swirl up in the summer wind, engulfing passers-by. The froth was the result of chemical waste dumped in the lake, and was toxic enough to crack windshields, wear the paint off car hoods and exacerbate the severe respiratory issues that have plagued citizens in recent years. Dr TV Ramachandra, coordinator of the Energy and Wetlands Research Group at the Indian Institute of Science (IISc), has been studying the lakes in Bangalore, especially Bellandur and Varthur, for over two decades. He explains that an estimated 400-600 million litres of untreated sewage is let into the lake catchment every day, creating a toxic environment fertile for disasters like the fires and foam. “The city overall generates between 1,400 and 1,600m litres per day of untreated sewage,” he says. “20-30m litres per day is generated from the apartments in the vicinity of Bellandur Lake. There are several invasive species like water hyacinths growing in the lake, thick enough to walk on. People dump solid waste on top of it. Because of the thickness, it creates an anaerobic environment in the water below, where methane is formed. It creates an ideal environment for catching fire.” He believes there are too many agencies governing the lake, so they all blame each other for such incidents. “The Bangalore water supply and sewerage board should be held responsible for letting the untreated sewage into the water,” he says, adding that the onus should also be placed on the Karnataka state pollution control board for not regulating industries that have been draining their untreated sewage into the lake. Although the Water (Prevention and Control of Pollution) Act and The Air (Prevention and Control of Pollution) Act require action to be taken over such matters, the government has mostly remained silent, while its departments have been passing the buck around. The National Green Tribunal has issued notices to all the agencies involved. Long before it began its slow and painful death, Bellandur Lake was part of a clever water and irrigation system devised by the founders of Bangalore in the 1600s, giving it the “city of lakes” moniker. The streams formed at the top of surrounding valleys were dammed into man-made lakes by constructing bunds. Each of these lakes would harvest rainwater from its catchments and the surplus would flow downstream, spilling into the next lake in the cascade via storm water drains or raja kaluves. The bodies of water would in turn serve the needs of the population. In the 1970s, there were still 285 lakes in the city, making it self-sufficient in its water needs. Today, however, there are just 194 lakes, and the large majority of them are sewage-fed. The rest have been lost to encroachments – by the Bangalore Development Authority, private real estate developers and illegal builders – to cater to the booming housing needs of a city of 10 million. Bangalore has been subject to unchecked urbanisation in the wake of the IT sector-fuelled economic boom of the late 1990s. The many software companies that sprung up during the dotcom boom attracted hundreds of thousands of skilled IT professionals from across the country, with thousands more people moving from villages and small towns to the city in search of work. According to studies by the IISc, rapid urbanisation and expansion between 1973 and 2016 caused a 1005% increase in paved surfaces and decline of 88% in the city’s vegetation, while water bodies declined by 85% between 2000 and 2014. The rise of the IT sector has also created the problem of e-waste in the city: a 2013 report estimated that Bangalore produces 20,000 tonnes of e-waste per year. Although a formal recycling system for e-waste was set up, 90% of it is dealt with through the informal sector, which is harder to monitor. Unaware of the necessary safety measures, some incinerate the e-waste, releasing lead, mercury and other toxins into the air – and dump the rest, allowing pollutants to infiltrate the groundwater. If one lake habitually catches fire, then another throws up thousands of dead fish every other summer. Ulsoor Lake, which doubles up as a picnic spot with boat rides and snack vendors on its banks, saw dead fish floating on its waters last year owing to the pollution caused by untreated sewage and consequent depletion of dissolved oxygen. The water pollution in Bangalore poses a serious threat to residents’ health and creates a chronic shortage of clean water for people to use. All in all, experts predict a severe water crisis which will make Bangalore uninhabitable by 2025, with residents potentially having to be evacuated. In the aftermath of the latest fire, I spoke to Aaditya Sood, an IT professional who watched the flames from his 10th floor balcony. He said he had seen the lake being “choked” in the seven or eight years he has lived there. “I have two kids and respiratory issues are a problem,” he says. The toxins from the lake get into the air, according to Ramachandra, noting that the cases of lung-related medical conditions have increased drastically in the city recently. Another resident, Vandana Sinha, who works for a consultancy firm, says the smoke from the fire almost immediately caused itchiness at the base of her throat. She had heard that seven to eight trucks worth of garbage was being dumped into the lake every night, adding to the lethal combination of pollutants in the waters. Report after report by expert committees have recommended several short and long term measures for rescuing the city’s lakes. Stopping the dumping of garbage, treating sewage water before it is allowed into the lakes, checking encroachments and slowing the development agenda are top of the list. In the next three years, if the same rate of development continues, the built up area in Bangalore is expected to increase from 77% to 93%, with a vegetation cover of a mere 3%. Ramachandra is determined to get the bureaucracy to act before it is too late. While the city may not fully cease to exist, without drastic improvement the other possibilities still sound impossibly grim. Follow Guardian Cities on Twitter and Facebook to join the discussion, and explore our archive here

Kishore V.,Physical Research Laboratory | Santhanam M.S.,Indian Institute of Science | Amritkar R.E.,Physical Research Laboratory
Physical Review Letters | Year: 2011

A wide spectrum of extreme events ranging from traffic jams to floods take place on networks. Motivated by these, we employ a random walk model for transport and obtain analytical and numerical results for the extreme events on networks. They reveal an unforeseen, and yet a robust, feature: small degree nodes of a network are more likely to encounter extreme events than the hubs. Further, we also study the recurrence time distribution and scaling of the probabilities for extreme events. These results suggest a revision of design principles and can be used as an input for designing the nodes of a network so as to smoothly handle extreme events. © 2011 American Physical Society.

Joanny J.-F.,University Pierre and Marie Curie | Ramaswamy S.,Indian Institute of Science
Journal of Fluid Mechanics | Year: 2012

We study theoretically the hydrodynamics of a fluid drop containing oriented filaments endowed with active contractile or extensile stresses and placed on a solid surface. The active stresses alter qualitatively the wetting properties of the drop, leading to new spreading laws and novel static drop shapes. Candidate systems for testing our predictions include cytoskeletal extracts with motors and ATP, suspensions of bacteria or pulsatile cells, or fluids laden with artificial self-propelled colloids. © 2011 Cambridge University Press.

Manikantan R.,Indian Institute of Science | Rajan K.,Microsoft | Govindarajan R.,Indian Institute of Science
Proceedings - International Symposium on Computer Architecture | Year: 2012

Effective sharing of the last level cache has a significant influence on the overall performance of a multicore system. We observe that existing solutions control cache occupancy at a coarser granularity, do not scale well to large core counts and in some cases lack the flexibility to support a variety of performance goals. In this paper, we propose Probabilistic Shared Cache Management (PriSM), a framework to manage the cache occupancy of different cores at cache block granularity by controlling their eviction probabilities. The proposed framework requires only simple hardware changes to implement, can scale to larger core count and is flexible enough to support a variety of performance goals. We demonstrate the flexibility of PriSM, by computing the eviction probabilities needed to achieve goals like hit-maximization, fairness and QOS. PriSM-HitMax improves performance by 18.7% over LRU and 11.8% over previously proposed schemes in a sixteen core machine. PriSM-Fairness improves fairness over existing solutions by 23.3% along with a performance improvement of 19.0%. PriSM-QOS successfully achieves the desired QOS targets. © 2012 IEEE.

Baswana S.,Indian Institute of Technology Kanpur | Kavitha T.,Indian Institute of Science
SIAM Journal on Computing | Year: 2010

Let G = (V, E) be a weighted undirected graph having nonnegative edge weights. An estimate δ̂(u, v) of the actual distance δ(u, v) between u, v ∈ V is said to be of stretch t if and only if δ(u, v) ≤ δ̂(u, v) ≤ t · δ(u, v). Computing all-pairs small stretch distances efficiently (both in terms of time and space) is a well-studied problem in graph algorithms. We present a simple, novel, and generic scheme for all-pairs approximate shortest paths. Using this scheme and some new ideas and tools, we design faster algorithms for all-pairs t-stretch distances for a whole range of stretch t, and we also answer an open question posed by Thorup and Zwick in their seminal paper [J. ACM, 52 (2005), pp. 1-24]. © 2010 Society for Industrial and Applied Mathematics.

Sathiya M.,CSIR - Central Electrochemical Research Institute | Prakash A.S.,CSIR - Central Electrochemical Research Institute | Ramesha K.,CSIR - Central Electrochemical Research Institute | Tarascon J.-M.,CNRS Laboratory of Chemistry and Reactivity of Solids | Shukla A.K.,Indian Institute of Science
Journal of the American Chemical Society | Year: 2011

Functionalized multiwalled carbon nanotubes (CNTs) are coated with a 4-5 nm thin layer of V2O5 by controlled hydrolysis of vanadium alkoxide. The resulting V2O5/CNT composite has been investigated for electrochemical activity with lithium ion, and the capacity value shows both faradaic and capacitive (nonfaradaic) contributions. At high rate (1 C), the capacitive behavior dominates the intercalation as 2/3 of the overall capacity value out of 2700 C/g is capacitive, while the remaining is due to Li-ion intercalation. These numbers are in agreement with the Trasatti plots and are corroborated by X-ray photoelectron spectroscopy (XPS) studies on the V2O5/CNTs electrode, which show 85% of vanadium in the +4 oxidation state after the discharge at 1 C rate. The cumulative high-capacity value is attributed to the unique property of the nano V2O 5/CNTs composite, which provides a short diffusion path for Li +-ions and an easy access to vanadium redox centers besides the high conductivity of CNTs. The composite architecture exhibits both high power density and high energy density, stressing the benefits of using carbon substrates to design high performance supercapacitor electrodes. © 2011 American Chemical Society.

Kayal N.,Microsoft | Saha C.,Indian Institute of Science | Saptharishi R.,Microsoft
Proceedings of the Annual ACM Symposium on Theory of Computing | Year: 2014

We consider arithmetic formulas consisting of alternating layers of addition (+) and multiplication (×) gates such that the fanin of all the gates in any fixed layer is the same. Such a formula Φ which additionally has the property that its formal/syntactic degree is at most twice the (total) degree of its output polynomial, we refer to as a regular formula. As usual, we allow arbitrary constants from the underlying field F on the incoming edges to a + gate so that a + gate can in fact compute an arbitrary F-linear combination of its inputs. We show that there is an (n2 + 1)-variate polynomial of degree 2n in VNP such that any regular formula computing it must be of size at least nΩ(log n). Along the way, we examine depth four (∑∏ ∑ ∏) regular formulas wherein all multiplication gates in the layer adjacent to the inputs have fanin a and all multiplication gates in the layer adjacent to the output node have fanin b. We refer to such formulas as ∑∏ [b]∑∏[a]-formulas. We show that there exists an n2-variate polynomial of degree n in VNP such that any ∑∏ [O√n)]∑∏ [√n]-formula computing it must have top fan-in at least 2 Ω( √n·log n). In comparison, Tavenas [Tav13] has recently shown that every nO(1)-variate polynomial of degree n in VP admits a ∑∏ [O√n)]∑∏ √n]-formula of top fan-in 2O√n·log n). This means that any further asymptotic improvement in our lower bound for such formulas (to say 2 ω √n log n)) will imply that VP is different from VNP. © 2014 ACM.

Roy A.,Physical Research Laboratory | Gautam S.,Indian Institute of Science | Angom D.,Physical Research Laboratory
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We show that the third Goldstone mode, which emerges in binary condensates at phase separation, persists to higher interspecies interaction for density profiles where one component is surrounded on both sides by the other component. This is not the case with symmetry-broken density profiles where one species is entirely to the left and the other is entirely to the right. We, then, use Hartree-Fock-Bogoliubov theory with Popov approximation to examine the mode evolution at T≠0 and demonstrate the existence of mode bifurcation near the critical temperature. The Kohn mode, however, exhibits deviation from the natural frequency at finite temperatures after the phase separation. This is due to the exclusion of the noncondensate atoms in the dynamics. © 2014 American Physical Society.

Chakravarty R.,Indian Institute of Science | Banerjee P.C.,Indian Institute of Science | Banerjee P.C.,Jadavpur University
Bioresource Technology | Year: 2012

Under certain conditions bacteria can act as a good biosorbent for different toxic heavy metals. However, no study on this aspect has been reported in case of acidophilic, heterotrophic, Gram-negative Acidiphilium strains, which are mostly resistant to several heavy metals. FTIR, SEM, TEM along with sorption experiments using bacterial cells of Acidiphilium symbioticum H8 were conducted to establish the mechanism of Cd 2+ ion sorption. The anionic functional groups present in the cell envelop were the components primarily responsible for the metal-binding capability of the bacterium. Sorption experiments further confirmed that 248.62mg of cadmium was adsorbed per gram biomass at pH 6.0. The process can better be explained by Langmuir-Freundlich dual isotherm model. Blocking of the functional groups by chemical modification suggested that the binding of cadmium on the biomass occurs through electrostatic reaction and complex formation. Accumulation of cadmium on the cell envelop was supported by fine structure study. © 2011 Elsevier Ltd.

Rana N.K.,Indian Institute of Technology Kanpur | Singh V.K.,Indian Institute of Technology Kanpur | Singh V.K.,Indian Institute of Science
Organic Letters | Year: 2011

Organocatalytic conjugate addition of thiols to R-substituted N-acryloyloxazolidin-2-ones followed by asymmetric protonation has been studied in the presence of cinchona alkaloid derived thioureas. Both of the enantiomers are accessible with the same level of enantioselectivity using pseudoenantiomeric quinine/quinidine derived catalysts. The addition/protonation products have been converted to useful biologically active molecules. ©2011 American Chemical Society.

Singh P.K.,Indian Institute of Technology Kanpur | Singh V.K.,Indian Institute of Technology Kanpur | Singh V.K.,Indian Institute of Science
Organic Letters | Year: 2010

"Chemical Equation Presented" A highly enantioselective Friedel-Crafts alkylation of pyrroles with 2-enoylpyridine 2-oxides catalyzed by chiral PYBOX-DIPH-Zn(II) complexes has been developed. The catalyst offers substantial substrate scope and furnished alkylated pyrroles in excellent yields (up to 99%) and enantioselectivities (up to >99% ee). © 2010 American Chemical Society.

Naldurg P.,Microsoft | Raghavendra K.R.,Indian Institute of Science
Proceedings of ACM Symposium on Access Control Models and Technologies, SACMAT | Year: 2011

We present SEAL, a language for specification and analysis of safety properties for label-based access control systems. A SEAL program represents a possibly infinite-state non-deterministic transition system describing the dynamic behavior of entities and their relevant access control operations. The features of our language are derived directly from the need to model new access control features arising from state-of-the art models in Windows 7, Asbestos, HiStar and others. We show that the reachability problem for this class of models is undecidable even for simple SEAL programs, but a bounded model-checking algorithm is able to validate interesting properties and discover relevant attacks. © 2011 ACM.

(—A small team of researchers with the Indian Institute of Science Education and Research has found that street dog mothers are not as willing to share meat with their pups as they are with other sources of food. In their paper published in Royal Society Open Science, the team describes experiments they carried out with semi-feral dogs, what they learned and why they believe their experiments offer evidence that suggests that dog domestication was more likely related to dog ancestors joining human civilizations than humans adopting wild puppies. In India, domesticated dogs are allowed to live freely in towns and cities among human inhabitants—they don't belong to anyone, instead, they live out their lives as semi-feral canines, existing on scraps, garbage or hand-outs. As the researchers note, very little research has been conducted on these street dogs, thus very little is known about their history or habits. After observing a mother with older pups refusing to share a bit of meat with her offspring, the researchers set up some experiments to learn if it was a common behavior or a onetime situation. The experiments consisted of offering food to a mother who still had pups traveling with her, but whose pups were all old enough to have been weaned. In the first experiment, the researchers tossed biscuits to 15 mother/litter groups and observed how they behaved, noting particularly how willing the mother was to share with her offspring. In the second set of experiments, they tossed pieces of raw chicken to 16 different mother/litter groups and once again watched to see how they behaved. In studying their data, the researchers found that during the biscuit experiments, the mothers were generally willing to share with their offspring—they did so freely approximately 75 percent of the time. When meat was doled out, however, things changed dramatically, there were conflicts approximately 80 percent of the time, straight away. Anyone who has ever owned a dog knows that meat is of particular importance to them, while they are able to digest carbohydrates, they still crave the protein in meat, as the mothers in the experiments in India showed. The researchers believe that craving for protein might have led the ancestors of modern dogs to hang around human settlements, which eventually led to full domestication, which suggests of course that such domestication was not due to humans adopting puppies, as has become the conventional view. Explore further: Does your dog love you? More information: Selfish mothers indeed! Resource-dependent conflict over extended parental care in free-ranging dogs, Royal Society Open Science, Published 9 December 2015.DOI: 10.1098/rsos.150580 , Abstract Parent–offspring conflict (POC) theory provides an interesting premise for understanding social dynamics in facultatively social species. In free-ranging dogs, mothers increase conflict over extended parental care with their pups beyond the weaning stage. In this study, we investigated whether resource quality affects POC in the dogs that typically live in a highly competitive environment as scavengers. We built a theoretical model to predict the alternative options available to the mother in the context of food sharing with her pups when protein-rich food (meat) is provided, as compared to carbohydrate-rich food (biscuits). We fit the mothers' response from experimental data to the model and show that the mothers choose a selfish strategy, which can in turn ensure higher lifetime reproductive success, while depriving the current litter access to better resources. These results have interesting implications for understanding the social dynamics of the dogs, and the emergence of facultative sociality in a species that evolved from strongly social ancestors. We speculate that the tendency of increased conflict in resource-rich conditions might have driven the process of domestication in the ancestors of dogs which defected from their groups in favour of richer resources around human settlements.

Bagchi B.,Indian Statistical Institute | Datta B.,Indian Institute of Science
European Journal of Combinatorics | Year: 2014

We introduce k-stellated spheres and consider the class Wk(d) of triangulated d-manifolds, all of whose vertex links are k-stellated, and its subclass Wk*(d), consisting of the (k + 1) -neighbourly members of Wk(d). We introduce the mu-vector of any simplicial complex and show that, in the case of 2-neighbourly simplicial complexes, the mu-vector dominates the vector of Betti numbers componentwise; the two vectors are equal precisely for tight simplicial complexes. We are able to estimate/compute certain alternating sums of the components of the mu-vector of any 2-neighbourly member of Wk(d) for d ≥ 2. k. As a consequence of this theory, we prove a lower bound theorem for such triangulated manifolds, and we determine the integral homology type of members of Wk*(d) for d ≥ 2. k + 2. As another application, we prove that, when d ≠ 2. k + 1, all members of Wk*(d) are tight. We also characterize the tight members of Wk*(2k+1) in terms of their kth Betti numbers. These results more or less answer a recent question of Effenberger, and also provide a uniform and conceptual tightness proof for all except two of the known tight triangulated manifolds.We also prove a lower bound theorem for homology manifolds in which the members of W1(d) provide the equality case. This generalizes a result (the d = 4 case) due to Walkup and Kühnel. As a consequence, it is shown that every tight member of W1(d) is strongly minimal, thus providing substantial evidence in favour of a conjecture of Kühnel and Lutz asserting that tight homology manifolds should be strongly minimal. © 2013 Elsevier Ltd.

Narendar S.,Indian Defence Research And Development Laboratory | Gopalakrishnan S.,Indian Institute of Science
Acta Mechanica | Year: 2012

This article presents the buckling analysis of orthotropic nanoplates such as graphene using the two-variable refined plate theory and nonlocal small-scale effects. The two-variable refined plate theory takes account of transverse shear effects and parabolic distribution of the transverse shear strains through the thickness of the plate, hence it is unnecessary to use shear correction factors. Nonlocal governing equations of motion for the monolayer graphene are derived from the principle of virtual displacements. The closed-form solution for buckling load of a simply supported rectangular orthotropic nanoplate subjected to in-plane loading has been obtained by using the Navier's method. Numerical results obtained by the present theory are compared with first-order shear deformation theory for various shear correction factors. It has been proven that the nondimensional buckling load of the orthotropic nanoplate is always smaller than that of the isotropic nanoplate. It is also shown that small-scale effects contribute significantly to the mechanical behavior of orthotropic graphene sheets and cannot be neglected. Further, buckling load decreases with the increase of the nonlocal scale parameter value. The effects of the mode number, compression ratio and aspect ratio on the buckling load of the orthotropic nanoplate are also captured and discussed in detail. The results presented in this work may provide useful guidance for design and development of orthotropic graphene based nanodevices that make use of the buckling properties of orthotropic nanoplates. © Springer-Verlag 2011.

Lee H.,Johns Hopkins University | Wang C.,Johns Hopkins University | Deshmukh S.S.,Johns Hopkins University | Deshmukh S.S.,Indian Institute of Science | Knierim J.J.,Johns Hopkins University
Neuron | Year: 2015

Classical theories of associative memory model CA3 as a homogeneous attractor network because of its strong recurrent circuitry. However, anatomical gradients suggest a functional diversity along the CA3 transverse axis. We examined the neural population coherence along this axis, when the local and global spatial reference frames were put in conflict with each other. Proximal CA3 (near the dentate gyrus), where the recurrent collaterals are the weakest, showed degraded representations, similar to the pattern separation shown by the dentate gyrus. Distal CA3 (near CA2), where the recurrent collaterals are the strongest, maintained coherent representations in the conflict situation, resembling the classic attractor network system. CA2 also maintained coherent representations. This dissociation between proximal and distal CA3 provides strong evidence that the recurrent collateral system underlies the associative network functions of CA3, with a separate role of proximal CA3 in pattern separation. © 2015 Elsevier Inc.

Reddy S.,Texas Instruments | Murthy C.R.,Indian Institute of Science
IEEE Transactions on Wireless Communications | Year: 2012

In this paper, we propose power management algorithms for maximizing the utility of energy harvesting sensors (EHS) that operate purely on the basis of energy harvested from the environment. In particular, we consider communication (i.e., transmission and reception) power management issues for EHS under an energy neutrality constraint. We also consider the fixed power loss effects of the circuitry, the battery inefficiency and its storage capacity, in the design of the algorithms. We propose a two-stage structure that exploits the inherent difference in the timescales at which the energy harvesting and channel fading processes evolve, without loss of optimality of the resulting solution. The outer stage schedules the power that can be used by an inner stage algorithm, so as to maximize the long term average utility and at the same time maintain energy neutrality. The inner stage optimizes the communication parameters to achieve maximum utility in the short-term, subject to the power constraint imposed by the outer stage. We optimize the algorithms for different transmission schemes such as the truncated channel inversion and retransmission strategies. The performance of the algorithms is illustrated via simulations using solar irradiance data, and for the case of Rayleigh fading channels. The results demonstrate the significant performance benefits that can be obtained using the proposed power management algorithms compared to the energy efficient (optimum when there is no storage) and the uniform power consumption (optimum when the battery has infinite capacity and is perfectly efficient) approaches. © 2012 IEEE.

Agency: Cordis | Branch: FP7 | Program: CSA | Phase: ICT-2011.3.4 | Award Amount: 466.53K | Year: 2011

The EU-INCOOP project objective is to stimulate cooperation in the computing technologies between Europe and India, in order to support Europes leading position in computing system, while ensuring mutual benefits for both Europe and India.\nThe project intends to take a consensus building approach by bringing together researchers and stakeholders from both regions under a common forum for discussing and analysing research agendas in computing systems.\nThrough the sequence of structured workshops, channels of communication will be established between the provider constituency, and the research community. The proposed work of EU-INCOOP is designed specifically to contribute to the coordination of ICT R&D related to international cooperation in computing systems. Our goals are: The coordination of the Computing Systems community within current projects in Europe and India, by providing a forum for the exchange of best practices, ideas and issues, as well as getting regional information for the collaborative research agenda development access to and visibility of requirements and perspectives opportunities to adjust and adapt to meet the international cooperation The development of Computing Systems roadmap for Europe and India, by providing:\ta channel for articulating the musts, needs and wants of the community: the positives and negatives - what is required and what is to be avoided, what are the priorities an interpretation or mapping into functional and technical requirements a feedback channel to the stakeholder community, and debating the impacts benefits and penalties, gains and costs, simplifications and complications

National Institute Of Immunology and Indian Institute of Science | Date: 2013-04-10

The present invention provides benzothiophene carboxamide compounds of formula I, their polymorphs, stereoisomers, prodrugs, solvates, pharmaceutically acceptable salts and formulations thereof, which are useful as COX-2 inhibitors and PfENR inhibitors. The invention further relates to pharmaceutical compositions containing such compounds and methods for their application as COX-2 inhibitors for treating inflammation and pain and PfENR inhibitors for use as anti-malarials.

Indian Institute of Science and National Institute Of Immunology | Date: 2011-07-14

The present invention provides benzothiophene carboxamide compounds of formula I, their polymorphs, stereoisomers, prodrugs, solvates, pharmaceutically acceptable salts and formulations thereof, which are useful as COX-2 inhibitors and PfENR inhibitors. The invention further relates to pharmaceutical compositions containing such compounds and methods for their application as COX-2 inhibitors for treating inflammation and pain and PfENR inhibitors for use as anti-malarials.

Rao C.N.R.,Jawaharlal Nehru Centre for Advanced Scientific Research | Rao C.N.R.,Indian Institute of Science | Gopalakrishnan K.,Jawaharlal Nehru Centre for Advanced Scientific Research | Govindaraj A.,Jawaharlal Nehru Centre for Advanced Scientific Research | Govindaraj A.,Indian Institute of Science
Nano Today | Year: 2014

Chemical doping of graphene becomes necessary to create a band gap which is useful for various applications. Furthermore, chemical doping of elements like boron and nitrogen in graphene gives rise to useful properties. Since chemically doped graphene is both of academic and technical importance, we have prepared this article on the present status of various aspects of this important class of materials. In doing so, we have covered the recent literature on this subject citing all the major references. Some of the aspects that we have covered are the synthesis of chemically doped graphene followed by properties and applications. The applications discussed relate to gas adsorption, lithium batteries, supercapacitors, oxygen reduction reaction, field emission and photochemical water splitting. Characterization of chemically doped graphene also included. We believe that the article will be useful to all those interested in graphene and related materials and provides the present status of the subject. © 2014 Elsevier Ltd.

Ubaidulla P.,Sudan University of Science and Technology | Chockalingam A.,Indian Institute of Science
IEEE Transactions on Signal Processing | Year: 2011

In this paper, we consider robust joint designs of relay precoder and destination receive filters in a nonregenerative multiple-input multiple-output (MIMO) relay network. The network consists of multiple source-destination node pairs assisted by a MIMO-relay node. The channel state information (CSI) available at the relay node is assumed to be imperfect. We consider robust designs for two models of CSI error. The first model is a stochastic error (SE) model, where the probability distribution of the CSI error is Gaussian. This model is applicable when the imperfect CSI is mainly due to errors in channel estimation. For this model, we propose robust minimum sum mean square error (SMSE), MSE-balancing, and relay transmit power minimizing precoder designs. The next model for the CSI error is a norm-bounded error (NBE) model, where the CSI error can be specified by an uncertainty set. This model is applicable when the CSI error is dominated by quantization errors. In this case, we adopt a worst-case design approach. For this model, we propose a robust precoder design that minimizes total relay transmit power under constraints on MSEs at the destination nodes. We show that the proposed robust design problems can be reformulated as convex optimization problems that can be solved efficiently using interior-point methods. We demonstrate the robust performance of the proposed design through simulations. © 2011 IEEE.

Chitara B.,Indian Institute of Science | Panchakarla L.S.,Jawaharlal Nehru Centre for Advanced Scientific Research | Krupanidhi S.B.,Indian Institute of Science | Rao C.N.R.,Jawaharlal Nehru Centre for Advanced Scientific Research
Advanced Materials | Year: 2011

The use of reduced graphene oxide (RGO) and graphene nanoribbons (GNRs) as infrared photodetectors is explored, based on recent results dealing with solar cells, light-emitting devices, photodetectors, and ultrafast lasers. IR detection is demonstrated by both RGO and GNRs (see image) in terms of the time-resolved photocurrent and photoresponse. The responsivity of the detectors and their functioning are presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bhowmick S.,Indian Institute of Science | Waghmare U.V.,Jawaharlal Nehru Centre for Advanced Scientific Research
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

Stone-Wales (SW) defects, analogous to dislocations in crystals, play an important role in mechanical behavior of s p2 -bonded carbon based materials. Here, we show using first-principles calculations that a marked anisotropy in the interaction among the SW defects has interesting consequences when such defects are present near the edges of a graphene nanoribbon: depending on their orientation with respect to edge, they result in compressive or tensile stress, and the former is responsible to depression or warping of the graphene nanoribbon. Such warping results in delocalization of electrons in the defect states. © 2010 The American Physical Society.

Bhattacharjee S.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Chemical Communications | Year: 2014

A Cu2+-selective metallo(hydro)gelation of a p-pyridyl ended oligo-phenylenevinylene system is reported over its respective meta- and ortho-regioisomers. The metallogel formed via the self-assembly of the nanoscale-metal-organic particles is injectable and also shows multi-stimuli responsiveness, including thixotropy. This journal is © the Partner Organisations 2014.

Narayanan R.,Indian Institute of Science | Johnston D.,University of Texas at Austin
Journal of Neurophysiology | Year: 2012

The presence and plasticity of dendritic ion channels are well established. However, the literature is divided on what specific roles these dendritic ion channels play in neuronal information processing, and there is no consensus on why neuronal dendrites should express diverse ion channels with different expression profiles. In this review, we present a case for viewing dendritic information processing through the lens of the sensory map literature, where functional gradients within neurons are considered as maps on the neuronal topograph. Under such a framework, drawing analogies from the sensory map literature, we postulate that the formation of intraneuronal functional maps is driven by the twin objectives of efficiently encoding inputs that impinge along different dendritic locations and of retaining homeostasis in the face of changes that are required in the coding process. In arriving at this postulate, we relate intraneuronal map physiology to the vast literature on sensory maps and argue that such a metaphorical association provides a fresh conceptual framework for analyzing and understanding single-neuron information encoding. We also describe instances where the metaphor presents specific directions for research on intraneuronal maps, derived from analogous pursuits in the sensory map literature. We suggest that this perspective offers a thesis for why neurons should express and alter ion channels in their dendrites and provides a framework under which active dendrites could be related to neural coding, learning theory, and homeostasis. © 2012 the American Physiological Society.

Kalidindi S.B.,Indian Institute of Science | Kalidindi S.B.,Ruhr University Bochum | Jagirdar B.R.,Indian Institute of Science
ChemSusChem | Year: 2012

Designing and developing ideal catalyst paves the way to green chemistry. The fields of catalysis and nanoscience have been inextricably linked to each other for a long time. Thanks to the recent advances in characterization techniques, the old technology has been revisited with a new scope. The last decade has witnessed a flood of research activity in the field of nanocatalysis, with most of the studies focusing on the effect of size on catalytic properties. This led to the development of much greener catalysts with higher activity, selectivity and greater ease of separation from the reaction medium. This Minireview describes the emerging trends in the field of nanocatalysis with implications towards green chemistry and sustainability. A fusion made in heaven: Collaboration of nanoscience with catalysis leads to the development of a new class of sustainable materials that fills the gap between homogeneous and heterogeneous catalysis. The advantages of nanosize in catalysis and its implications key issues in catalysis, such as activity, selectivity, and separation from the reaction medium, are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ghosh S.,Indian Institute of Science | Mallick B.,Indian Institute of Science | Nagaraja V.,Jawaharlal Nehru Centre for Advanced Scientific Research
Nucleic acids research | Year: 2014

The topological homeostasis of bacterial chromosomes is maintained by the balance between compaction and the topological organization of genomes. Two classes of proteins play major roles in chromosome organization: the nucleoid-associated proteins (NAPs) and topoisomerases. The NAPs bind DNA to compact the chromosome, whereas topoisomerases catalytically remove or introduce supercoils into the genome. We demonstrate that HU, a major NAP of Mycobacterium tuberculosis specifically stimulates the DNA relaxation ability of mycobacterial topoisomerase I (TopoI) at lower concentrations but interferes at higher concentrations. A direct physical interaction between M. tuberculosis HU (MtHU) and TopoI is necessary for enhancing enzyme activity both in vitro and in vivo. The interaction is between the amino terminal domain of MtHU and the carboxyl terminal domain of TopoI. Binding of MtHU did not affect the two catalytic trans-esterification steps but enhanced the DNA strand passage, requisite for the completion of DNA relaxation, a new mechanism for the regulation of topoisomerase activity. An interaction-deficient mutant of MtHU was compromised in enhancing the strand passage activity. The species-specific physical and functional cooperation between MtHU and TopoI may be the key to achieve the DNA relaxation levels needed to maintain the optimal superhelical density of mycobacterial genomes. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Bhattacharyya S.,Indian Institute of Science | Varadarajan R.,Indian Institute of Science | Varadarajan R.,Jawaharlal Nehru Centre for Advanced Scientific Research
Current Opinion in Structural Biology | Year: 2013

Close packing of hydrophobic residues in the protein interior is an important determinant of protein stability. Cavities introduced by large to small substitutions are known to destabilize proteins. Conversely, native states of proteins and protein fragments can be stabilized by filling in existing cavities. Molten globules (MGs) were initially used to describe a state of protein which has well-defined secondary structure but little or no tertiary packing. Subsequent studies have shown that MGs do have some degree of native-like topology and specific packing. Wet molten globules (WMGs) with hydrated cores and considerably decreased packing relative to the native state have been studied extensively. Recently there has been renewed interest in identification and characterization of dry molten globules (DMGs). These are slightly expanded forms of the native state which show increased conformational flexibility, native-like main-chain hydrogen bonding and dry interiors. The generality of occurrence of DMGs during protein unfolding and the extent and nature of packing in DMGs remain to be elucidated. Packing interactions in native proteins and MGs can be probed through mutations. Next generation sequencing technologies make it possible to determine relative populations of mutants in a large pool. When this is coupled to phenotypic screens or cell-surface display, it becomes possible to rapidly examine large panels of single-site or multi-site mutants. From such studies, residue specific contributions to protein stability and function can be estimated in a highly parallelized fashion. This complements conventional biophysical methods for characterization of packing in native states and molten globules. © 2012 Elsevier Ltd.

Maji B.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Chemical Communications | Year: 2014

Telomerases are an attractive drug target to develop new generation drugs against cancer. A telomere appears from the chromosomal termini and protects it from double-stranded DNA degradation. A short telomere promotes genomic instability, like end-to-end fusion and regulates the over-expression of the telomere repairing enzyme, telomerase. The telomerase maintains the telomere length, which may lead to genetically abnormal situations, leading to cancer. Thus, the design and synthesis of an efficient telomerase inhibitor is a viable strategy toward anticancer drugs development. Accordingly, small molecule induced stabilization of the G-quadruplex structure, formed by the human telomeric DNA, is an area of contemporary scientific art. Several such compounds efficiently stabilize the G-quadruplex forms of nucleic acids, which often leads to telomerase inhibition. This Feature article presents the discovery and development of the telomere structure, function and evolution in telomere targeted anticancer drug design and incorporates the recent advances in this area, in addition to discussing the advantages and disadvantages in the methods, and prospects for the future. This journal is © the Partner Organisations 2014.

Datta S.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Chemical Society Reviews | Year: 2015

The remarkable capability of nature to design and create excellent self-assembled nano-structures, especially in the biological world, has motivated chemists to mimic such systems with synthetic molecular and supramolecular systems. The hierarchically organized self-assembly of low molecular weight gelators (LMWGs) based on non-covalent interactions has been proven to be a useful tool in the development of well-defined nanostructures. Among these, the self-assembly of sugar-derived LMWGs has received immense attention because of their propensity to furnish biocompatible, hierarchical, supramolecular architectures that are macroscopically expressed in gel formation. This review sheds light on various aspects of sugar-derived LMWGs, uncovering their mechanisms of gelation, structural analysis, and tailorable properties, and their diverse applications such as stimuli-responsiveness, sensing, self-healing, environmental problems, and nano and biomaterials synthesis. This journal is © The Royal Society of Chemistry.

Nagamanasa K.H.,Jawaharlal Nehru Centre for Advanced Scientific Research | Gokhale S.,Indian Institute of Science | Sood A.K.,Indian Institute of Science | Sood A.K.,Jawaharlal Nehru Centre for Advanced Scientific Research | Ganapathy R.,Jawaharlal Nehru Centre for Advanced Scientific Research
Nature Physics | Year: 2015

The transformation of flowing liquids into rigid glasses is thought to involve increasingly cooperative relaxation dynamics as the temperature approaches that of the glass transition. However, the precise nature of this motion is unclear, and a complete understanding of vitrification thus remains elusive. Of the numerous theoretical perspectives devised to explain the process, random first-order theory (RFOT; refs, 2,5) is a well-developed thermodynamic approach, which predicts a change in the shape of relaxing regions as the temperature is lowered. However, the existence of an underlying ' ideal' glass transition predicted by RFOT remains debatable, largely because the key microscopic predictions concerning the growth of amorphous order and the nature of dynamic correlations lack experimental verification. Here, using holographic optical tweezers, we freeze a wall of particles in a two-dimensional colloidal glass-forming liquid and provide direct evidence for growing amorphous order in the form of a static point-to-set length. We uncover the non-monotonic dependence of dynamic correlations on area fraction and show that this non-monotonicity follows directly from the change in morphology and internal structure of cooperatively rearranging regions. Our findings support RFOT and thereby constitute a crucial step in distinguishing between competing theories of glass formation.

Gupta A.,Indian Institute of Science | Waghmare U.V.,Jawaharlal Nehru Centre for Advanced Scientific Research | Hegde M.S.,Indian Institute of Science
Chemistry of Materials | Year: 2010

Oxygen storage/release (OSC) capacity is an important feature common to all three-way catalysts to combat harmful exhaust emissions. To understand the mechanism of improved OSC for doped CeO2, we undertook the structural investigation by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-TPR (temperature-programmed hydrogen reduction) and density functional theoretical (DFT) calculations of transition-metal-, noble-metal-, and rare-earth (RE)-ion-substituted ceria. In this report, we present the relationship between the OSC and structural changes induced by the dopant ion in CeO2. Transition metal and noble metal ion substitution in ceria greatly enhances the reducibility of Ce1-xMxO 2-δ (M = Mn, Fe, Co, Ni, Cu, Pd, Pt, Ru), whereas rare-earth-ion-substituted Ce1-xAxO2-δ (A = La, Y) have very little effect in improving the OSC. Our simulated optimized structure shows deviation in cation-oxygen bond length from ideal bond length of 2.34 Å (for CeO2). For example, our theoretical calculation for Ce28Mn4O62 structure shows that Mn-O bonds are in 4 + 2 coordination with average bond lengths of 2.0 and 3.06 Å respectively. Although the four short Mn-O bond lengths spans the bond distance region of Mn2O3, the other two Mn-O bonds are moved to longer distances. The dopant transition and noble metal ions also affects Ce coordination shell and results in the formation of longer Ce-O bonds as well. Thus longer cation-oxygen bonds for both dopant and host ions results in enhanced synergistic reduction of the solid solution. With Pd ion substitution in Ce1-xMxO2-δ (M = Mn Fe, Co, Ni, Cu) further enhancement in OSC is observed in H2-TPR. This effect is reflected in our model calculations by the presence of still longer bonds compared to the model without Pd ion doping. The synergistic effect is therefore due to enhanced reducibility of both dopant and host ion induced due to structural distortion of fluorite lattice in presence of dopant ion. For RE ions (RE = Y, La), our calculations show very little deviation of bonds lengths from ideal fluorite structure. The absence of longer Y-O/La-O and Ce-O bonds make the structure much less susceptible to reduction. © 2010 American Chemical Society.

Karmakar S.,The Interdisciplinary Center | Dasgupta C.,Indian Institute of Science | Sastry S.,The Interdisciplinary Center | Sastry S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Annual Review of Condensed Matter Physics | Year: 2014

The question of whether the dramatic slowing down of the dynamics of glass-forming liquids near the structural glass transition is caused by the growth of one or more correlation lengths has received much attention in recent years. Several proposals have been made for both static and dynamic length scales that may be responsible for the growth of timescales as the glass transition is approached. These proposals are critically examined with emphasis on the dynamic length scale associated with spatial heterogeneity of local dynamics and the static point-to-set or mosaic length scale of the random first-order transition theory of equilibrium glass transition. Available results for these length scales, obtained mostly from simulations, are summarized, and the relation of the growth of timescales near the glass transition with the growth of these length scales is examined. Some of the outstanding questions about length scales in glass-forming liquids are discussed, and studies in which these questions may be addressed are suggested. © Copyright 2014 by Annual Reviews. All rights reserved.

Raje D.,Indian Institute of Tropical Meteorology | Mujumdar P.P.,Indian Institute of Science
Hydrological Processes | Year: 2011

Many downscaling techniques have been developed in the past few years for projection of station-scale hydrological variables from large-scale atmospheric variables simulated by general circulation models (GCMs) to assess the hydrological impacts of climate change. This article compares the performances of three downscaling methods, viz. conditional random field (CRF), K-nearest neighbour (KNN) and support vector machine (SVM) methods in downscaling precipitation in the Punjab region of India, belonging to the monsoon regime. The CRF model is a recently developed method for downscaling hydrological variables in a probabilistic framework, while the SVM model is a popular machine learning tool useful in terms of its ability to generalize and capture nonlinear relationships between predictors and predictand. The KNN model is an analogue-type method that queries days similar to a given feature vector from the training data and classifies future days by random sampling from a weighted set of K closest training examples. The models are applied for downscaling monsoon (June to September) daily precipitation at six locations in Punjab. Model performances with respect to reproduction of various statistics such as dry and wet spell length distributions, daily rainfall distribution, and intersite correlations are examined. It is found that the CRF and KNN models perform slightly better than the SVM model in reproducing most daily rainfall statistics. These models are then used to project future precipitation at the six locations. Output from the Canadian global climate model (CGCM3) GCM for three scenarios, viz. A1B, A2, and B1 is used for projection of future precipitation. The projections show a change in probability density functions of daily rainfall amount and changes in the wet and dry spell distributions of daily precipitation. © 2011 John Wiley & Sons, Ltd.

Rubatto D.,Australian National University | Chakraborty S.,Ruhr University Bochum | Dasgupta S.,Indian Institute of Science
Contributions to Mineralogy and Petrology | Year: 2013

The petrology and timing of crustal melting has been investigated in the migmatites of the Higher Himalayan Crystalline (HHC) exposed in Sikkim, India. The metapelites underwent pervasive partial melting through hydrous as well as dehydration melting reactions involving muscovite and biotite to produce a main assemblage of quartz, K-feldspar, plagioclase, biotite, garnet ± sillimanite. Peak metamorphic conditions were 8-9 kbar and ~800 °C. Monazite and zircon crystals in several migmatites collected along a N-S transect show multiple growth domains. The domains were analyzed by microbeam techniques for age (SHRIMP) and trace element composition (LA-ICP-MS) to relate ages to conditions of formation. Monazite preserves the best record of metamorphism with domains that have different zoning pattern, composition and age. Zircon was generally less reactive than monazite, with metamorphic growth zones preserved in only a few samples. The growth of accessory minerals in the presence of melt was episodic in the interval between 31 and 17 Ma, but widespread and diachronous across samples. Systematic variations in the chemical composition of the dated mineral zones (HREE content and negative Eu anomaly) are related to the variation in garnet and K-feldspar abundances, respectively, and thus to metamorphic reactions and P-T stages. In turn, this allows prograde versus decompressional and retrograde melt production to be timed. A hierarchy of timescales characterizes melting which occurred over a period of ~15 Ma (31-17 Ma): a given block within this region traversed the field of melting in 5-7 Ma, whereas individual melting reactions lasted for time durations below, or approaching, the resolution of microbeam dating techniques (~0.6 Ma). An older ~36 Ma high-grade event is recorded in an allocthonous relict related to mafic lenses. We identify two sections of the HHC in Sikkim that traversed similar P-T conditions at different times, separated by a tectonic discontinuity. The higher structural levels reached melting and peak conditions later (~26-23 Ma) than the lower structural levels (~31-27 Ma). Diachronicity across the HHC cannot be reconciled with channel flow models in their simplest form, as it requires two similar high-grade sections to move independently during collision. © 2012 Springer-Verlag.

Bhowmik S.,Indian Institute of Science | Maitra U.,Indian Institute of Science | Maitra U.,Jawaharlal Nehru Centre for Advanced Scientific Research
Chemical Communications | Year: 2012

Chemically synthesized "pro-sensitizers" release the sensitizer in the presence of lipase or β-glucosidase, triggering a significant luminescence response from a lanthanide based hydrogel. This journal is © The Royal Society of Chemistry 2012.

Datta S.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Chemical Communications | Year: 2012

A novel salicylideneaniline type fluorescent organogelator based on a 3,4,5-(tri-dodecyloxy)benzoyl group immobilizes aromatic solvents. The resulting gels show enhancement in emission and thermochromic/non-photochromic behaviour during sol-to-gel transition.

Samanta S.K.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Journal of Materials Chemistry | Year: 2012

Supramolecular π-gels were formed in a mixture of aliphatic alcohols and water for a series of chromophoric phenylenedivinylene bis-N-alkyl pyridinium salts (PPV) appended with terminal aliphatic hydrocarbon chains of different lengths. Gelation could be controlled either by altering the ratio of various alcohol-water mixtures or by changing the aliphatic chain length of the gelator. The temperature- and the ratio-variation in the ethanol-water mixtures exhibited a tunable emission behavior depending on the extent of aggregation which was promoted by aromatic π-stacking, van der Waals and electrostatic interactions among the individual PPV units. Thus, a light-blue emission at higher temperature (>40°C), a reddish-orange emission at low temperature (<20°C) and a white-light emission at room temperature (25-30°C) were observed in solution. The gelators possessing longer aliphatic chains exhibited a higher gel-melting temperature, increased viscoelasticity and shorter fiber diameter based on a delicate hydrophobic/hydrophilic balance. A semiconducting nature of the electrical conductivity was observed for the individual compounds and the magnitude of the current increased with increasing width of the gel fibers upon decreasing the aliphatic chain length. A reversible one-electron redox behavior was observed for the chromophore and the redox potential decreased with the increase in the chain length. A diffusion-controlled redox behavior was observed for the gelators with shorter aliphatic chains. However, the compounds with longer chains made the process diffusion-limited. © 2012 The Royal Society of Chemistry.

Misra S.K.,Indian Institute of Science | Kondaiah P.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Rao C.N.R.,Jawaharlal Nehru Centre for Advanced Scientific Research
Small | Year: 2012

A cationic amphiphile, cholest-5en-3β-oxyethyl pyridinium bromide (PY +-Chol), is able to efficiently disperse exfoliated graphene (GR) in water by the physical adsorption of PY +-Chol on the surface of GR to form stable, dark aqueous suspensions at room temperature. The GR-PY +-Chol suspension can then be used to solubilize Tamoxifen Citrate (TmC), a breast cancer drug, in water. The resulting TmC-GR-PY +-Chol is stable for a long time without any precipitation. Fluorescence emission and UV absorption spectra indicate the existence of noncovalent interactions between TmC, GR, and PY +-Chol in these suspensions. Electron microscopy shows the existence of segregated GR sheets and TmC 'ribbons' in the composite suspensions. Atomic force microscopy indicates the presence of 'extended' structures of GR-PY +-Chol, which grows wider in the presence of TmC. The slow time-dependent release of TmC is noticed in a reconstituted cell culture medium, a property useful as a drug carrier. TmC-GR-PY +-Chol selectively enhanced the cell death (apoptosis) of the transformed cancer cells compared to normal cells. This potency is found to be true for a wide range of transformed cancer cells viz. HeLa, A549, ras oncogene-transformed NIH3T3, HepG2, MDA-MB231, MCF-7, and HEK293T compared to the normal cell HEK293 in vitro. Confocal microscopy confirmed the high efficiency of TmC-GR-PY +-Chol in delivering the drug to the cells, compared to the suspensions devoid of GR. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vasu K.,Indian Institute of Science | Nagaraja V.,Indian Institute of Science | Nagaraja V.,Jawaharlal Nehru Centre for Advanced Scientific Research
Microbiology and Molecular Biology Reviews | Year: 2013

Restriction-modification (R-M) systems are ubiquitous and are often considered primitiveimmunesystems in bacteria. Their diversity and prevalence across the prokaryotic kingdom are an indication of their success as a defense mechanism against invading genomes. However, their cellular defense function does not adequately explain the basis for their immaculate specificity in sequence recognition and nonuniform distribution, ranging from none to too many, in diverse species. The present review deals with new developments which provide insights into the roles of these enzymes in other aspects of cellular function. In this review, emphasis is placed on novel hypotheses and various findings that have not yet been dealt with in a critical review. Emerging studies indicate their role in various cellular processes other than host defense, virulence, and even controlling the rate of evolution of the organism. We also discuss how R-M systems could have successfully evolved and be involved in additional cellular portfolios, thereby increasing the relative fitness of their hosts in the population. Copyright © 2013, American Society for Microbiology. All Rights Reserved.

Kesavardhana S.,Indian Institute of Science | Varadarajan R.,Jawaharlal Nehru Centre for Advanced Scientific Research
Journal of virology | Year: 2014

UNLABELLED: The HIV-1 envelope glycoprotein (Env) is a trimer of gp120-gp41 heterodimers and is essential for viral entry. The gp41 subunit in native, prefusion trimeric Env exists in a metastable conformation and attains a stable six-helix bundle (6-HB) conformation comprised of a trimer of N-heptad repeat (NHR) and C-heptad repeat (CHR) heterodimers, that drives the fusion of viral and cellular membranes. We attempted to stabilize native Env trimers by incorporation of mutations at the NHR-CHR interface that disrupt the postfusion 6-HB of gp41. The mutations V570D and I573D stabilize native Env of the HIV-1 JRFL strain and occlude nonneutralizing epitopes to a greater extent than the previously identified I559P mutation that is at the interface of the NHR trimers in the 6-HB. The mutations prevent soluble-CD4 (sCD4)-induced gp120 shedding and 6-HB formation. In the context of cell surface-expressed JRFL Env, introduction of a previously reported additional disulfide between residues A501 and T605 perturbs the native conformation, though this effect is partially alleviated by furin coexpression. The data suggest that positions 570 and 573 are surface proximal in native Env and that the NHR homotrimeric coiled coil in native Env terminates before or close to residue 573. Aspartic acid substitutions at these positions stabilize native trimers through destabilization of the postfusion 6-HB conformation. These mutations can be used to stabilize Env in a DNA vaccine format.IMPORTANCE: The major protein on the surface of HIV-1 is the envelope (Env) glycoprotein. Env is a trimer of gp120-gp41 heterodimers. gp120 is involved in receptor/coreceptor binding and gp41 in the fusion of viral and cellular membranes. Like many other viral fusion proteins, the gp41 subunit in native trimeric Env exists in a metastable conformation. gp41 readily forms a stable six-helix bundle (6-HB) conformation comprised of a trimer of N-heptad repeat (NHR) and C-heptad repeat (CHR) heterodimers that drives fusion of viral and cellular membranes. While it is expected that native Env is a good immunogen, its metastability results in exposure of immunodominant nonneutralizing epitopes. In the present study, we stabilize native Env trimers by incorporation of a number of different mutations at the NHR-CHR interface that disrupt the postfusion 6-HB of gp41. The stabilized constructs described here can be incorporated into DNA vaccine candidates. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Samanta S.K.,Indian Institute of Science | Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Chemistry - A European Journal | Year: 2012

We have synthesized two new low-molecular-mass organogelators based on tri-p-phenylene vinylene derivatives, one of which could be designated as the donor whereas the other one is an acceptor. These were prepared specifically to show the intergelator interactions at the molecular level by using donor-acceptor self-assembly to achieve appropriate control over their macroscopic properties. Intermolecular hydrogen-bonding, π-stacking, and van der Waals interactions operate for both the individual components and the mixtures, leading to the formation of gels in the chosen organic solvents. Evidence for intergelator interactions was acquired from various spectroscopic, microscopic, thermal, and mechanical investigations. Due to the photochromic nature of these molecules, interesting photophysical properties, such as solvatochromism and J-type aggregation, were clearly observed. An efficient energy transfer was exhibited by the mixture of donor-acceptor assemblies. An array of four chromophores was built up by inclusion of two known dyes (anthracene and rhodamine 6G) for the energy-transfer studies. Interestingly, an energy-transfer cascade was observed in the assembly of four chromophores in a particular order (anthracene-donor-acceptor-rhodamine 6G), and if one of the components was removed from the assembly the energy transfer process was discontinued. This allowed the build up of a light-harvesting process with a wide range. Excitation at one end produces an emission at the other end of the assembly. Join the cascade! Intergelator interactions between two p-phenylene-vinylene-based, low-molecular-mass gelators formed through donor-acceptor assembly have been demonstrated. A cascade energy transfer was described in an assembly of four different chromophores in a particular order. In this assembly, excitation at the first chromophore produces an emission at the fourth, thus establishing a wide-range light-harvesting process (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bhattacharya S.,Indian Institute of Science | Bhattacharya S.,Jawaharlal Nehru Centre for Advanced Scientific Research | Samanta S.K.,Indian Institute of Science
Chemistry - A European Journal | Year: 2012

The synthesis, hydrogelation, and aggregation-induced emission switching of the phenylenedivinylene bis-N-octyl pyridinium salt is described. Hydrogelation occurs as a consequence of π-stacking, van der Waals, and electrostatic interactions that lead to a high gel melting temperature and significant mechanical properties at a very low weight percentage of the gelator. A morphology transition from fiber-to-coil-to-tube was observed depending on the concentration of the gelator. Variation in the added salt type, salt concentrations, or temperature profoundly influenced the order of aggregation of the gelator molecules in aqueous solution. Formation of a novel chromophore assembly in this way leads to an aggregation-induced switch of the emission colors. The emission color switches from sky blue to white to orange depending upon the extent of aggregation through mere addition of external inorganic salts. Remarkably, the salt effect on the assembly of such cationic phenylenedivinylenes in water follow the behavior predicted from the well-known Hofmeister effects. Mechanistic insights for these aggregation processes were obtained through the counterion exchange studies. The aggregation-induced emission switching that leads to a room-temperature white-light emission from a single chromophore in a single solvent (water) is highly promising for optoelectronic applications. Worth its salt: The π hydrogelation of a phenylenedivinylene bis-pyridinium salt is described. Variations in the amount of salts or temperature resulted in an aggregation-induced switch of emission colors (see figure). Thus, room-temperature white-light emission is generated from a single chromophore in a single solvent. The effect of different anions and cations on the aggregation follows the Hofmeister series. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rao S.A.M.,Indian Institute of Science | Santosh V.,National Institute of Mental Health and Neuro Sciences | Somasundaram K.,Indian Institute of Science
Modern Pathology | Year: 2010

Malignant astrocytoma includes anaplastic astrocytoma (grade III) and glioblastoma (grade IV). Among them, glioblastoma is the most common primary brain tumor with dismal responses to all therapeutic modalities. We performed a large-scale, genome-wide microRNA (miRNA) (n756) expression profiling of 26 glioblastoma, 13 anaplastic astrocytoma and 7 normal brain samples with an aim to find deregulated miRNA in malignant astrocytoma. We identified several differentially regulated miRNAs between these groups, which could differentiate glioma grades and normal brain as recognized by PCA. More importantly, we identified a most discriminatory 23-miRNA expression signature, by using PAM, which precisely distinguished glioblastoma from anaplastic astrocytoma with an accuracy of 95%. The differential expression pattern of nine miRNAs was further validated by real-time RT-PCR on an independent set of malignant astrocytomas (n72) and normal samples (n7). Inhibition of two glioblastoma-upregulated miRNAs (miR-21 and miR-23a) and exogenous overexpression of two glioblastoma- downregulated miRNAs (miR-218 and miR-219-5p) resulted in reduced soft agar colony formation but showed varying effects on cell proliferation and chemosensitivity. Thus we have identified the miRNA expression signature for malignant astrocytoma, in particular glioblastoma, and showed the miRNA involvement and their importance in astrocytoma development. © 2010 USCAP, Inc. All rights reserved.

News Article | November 2, 2016

AN ICONIC physics experiment may be hiding more than we ever realised about the nature of reality. The classic “double-slit” experiment reveals the strange duality of the quantum world, but it may behave more strangely than we thought – and could challenge one of the most closely held assumptions of quantum mechanics. Revisiting it could help unify quantum mechanics with the other pillar of theoretical physics – Einstein’s general relativity – a challenge that has so far proven intractable. The double-slit experiment involves shining a light at two close-together slits placed in front of a screen. Our classical view of the world suggests that photons of light should pass through one slit or the other, and thus create two parallel bands on the screen behind. But instead, the light spreads out into alternating bands of light and dark. This interference pattern appears even if you send in one photon at a time, suggesting that rather than moving in a straight line, light behaves as both a wave and a particle at the same time. US physicist Richard Feynman said this experiment embodies the “central mystery” of the quantum world. “Every student of quantum physics is taught how to calculate the interference pattern of the double-slit experiment,” says James Quach at the Barcelona Institute of Science and Technology in Spain. To calculate the probability that a photon will arrive at some location on the screen, physicists use a principle called the Born rule. However, there is no fundamental reason why the Born rule should hold. It seems to work in all the situations we’ve tested, but no one knows why. Some have attempted to derive it from the “many worlds” interpretation of quantum mechanics, which proposes that all the possible states of a quantum system could exist in different, parallel universes – but such attempts have been inconclusive. That makes the Born rule a good place to look for cracks in quantum theory. To unite quantum mechanics, which governs the universe on minute scales, and general relativity, which holds at immense scales, one of the theories must give way. If the Born rule falls over, it could clear a path to quantum gravity. “If the Born rule is violated, then a fundamental axiom of quantum mechanics has been violated, and it should point to where one needs to go to find quantum gravitational theories,” says Quach. Now, Quach has suggested a new way to test the Born rule. He started from another idea of Feynman’s: in order to calculate the probability of a particle reaching a certain place on the screen, you should account for all the possible paths it could take from the source to the screen, even ones that seem ridiculous. “This includes paths that go from here to the moon and back again,” says Quach. Almost none of these paths should affect the photon’s final location, but there are some weird paths that could change the probabilities enough for us to measure the difference. “If the Born rule is violated, it should point to how to find a theory of quantum gravity“ For instance, say there are three paths that a particle could take through the apparatus instead of the obvious two. The Born rule lets you calculate probabilities by considering interference between pairs of paths, but not between all three paths at once. Quach shows that if you account for interference between all three paths, the probabilities will be different from what the Born rule predicts ( He suggests testing this with a double-slit experiment that allows for a third path, a wandering zigzag in which the particle goes through the left slit, over to the right slit, then heads towards the screen. If that third path interferes with the two more straightforward ones, the results should deviate from what the Born rule suggests. Quach’s work is “extremely interesting and thought-provoking”, says Aninda Sinha at the Indian Institute of Science in Bangalore, a member of the team that first proposed exploring violations of the Born rule using winding, non-classical paths. But he points out that Quach’s experiment could fail to capture other paths that might muddy the results. The stakes are high. Finding violations of the Born rule could be the thin edge of the wedge that pries open the door to a more fundamental understanding of reality. This article appeared in print under the headline “Double-slit jeopardy”

News Article | August 7, 2015

To solve its energy crisis in a coal-dependent country and to reach its goal toward becoming one of the world's largest solar markets, India is launching a new concentrated solar power project in a few weeks. Run by the Indian Institute of Science (IISC) as part of the Solar Energy Research Institute for India and the United States (Seriius), the project consists of rows of aluminum troughs that will generate solar-powered electricity. Sunlight that reflects from the troughs will bounce to water pipes located above. The water in the pipes will be heated to 392 degrees Fahrenheit and go through a heat exchanger that is attached to a small machine used for producing power from fast-flowing water, which will then create 100 kilowatts of electricity. The researchers will then be able to test various reflective heat-transferable liquids, such as molten salt, to produce electricity. They will gather and analyze data sent to a dashboard at IISC from small wireless sensors with the goal of finding the best components to produce solar power in India as many of the solar panels the country received are not suited for the extreme conditions of its climate. Along with testing concentrated solar power, solar photovoltaic installations will also be added, and researchers will focus on creating polymers to protect the panels from extreme conditions like high temperatures and dust. While the project may lead to the solution for the deterioration of solar panels, the researchers have another problem on their hands — monkeys. The installation set in Challakere, north of Bangalore, is often invaded by monkeys that are wreaking havoc on the solar panels. The monkeys are said to chew on the electrical cables and even lick the panels that collect dew. "We've tried giving them food to lure them away, but they just sit there," professor of materials engineering at IISC Praveen Ramamurthy said. "I don't know what to do." To address the monkey problem, the researchers have even tried an ultrasonic monkey repellent to keep the animals away from the project, but they just keep coming back. While the panels provide a hangout spot for the primates, the project will help India progress toward providing clean energy to the more than 300 million people who live without it.

News Article | March 7, 2016

The Indian government’s annual budget, announced on Feb. 29, increases funding for science and technology, scientific research, and biotechnology within the Ministry of Science & Technology. Budgetary estimates for the Department of Science & Technology (DST), India’s central agency for disbursing research grants in science, are $660 million, up by almost 17% over last year. Health research funding would be hiked by $20 million, or 12.5%, over last year. In contrast, the Department of Scientific & Industrial Research, which promotes domestic technology development and transfer, would receive a paltry rise of 0.7% compared with the previous year. The government plans to pour $269 million into its Department of Biotechnology (DBT), a 12% hike over last year. The increase might seem marginal given the ambitious national strategy launched in December 2015 to turn India into a world hub for biotechnology by 2020. The program is expanding research in vaccines, the human genome, infectious and chronic diseases, crop science, animal agriculture and aquaculture, food and nutrition, environmental management, and clean energy technologies. Despite the increase in biotechnology funding being below expectations, DBT Secretary Krishnaswamy VijayRaghavan is confident of acquiring the required funds from other sources. He, however, did not elaborate on what those sources could be. The general enhancement of the annual budget’s allocation, VijayRaghavan says, will help DBT give a major push to programs and activities for national initiatives, including Make in India, Start-up India, and Swachh Bharat (Clean India). Under the increased outlay for Swachh Bharat, development of some new technologies will be given a significant boost, he says. Also in the budget, funding for new and renewable energy received a nearly 17-fold jump. This is to be supported in part by the government’s proposed increase in the nation’s tax on coal, called the Clean Environment Cess. Although the government announced new initiatives for the country’s distressed agricultural sector, their thrust was on infrastructure development and providing insurance to farmers. The outlay for agricultural research and education increased by less than 5%. C. N. R. Rao, a chemist and research professor at Jawaharlal Nehru Centre for Advanced Scientific Research, says, “The budgets of DST and DBT are good and should boost the morale of scientists.” However, Krishna N. Ganesh, a chemistry professor and director of the Indian Institute of Science Education & Research, Pune, tells C&EN that the scientific community has few reasons to cheer. Compared with the 2015–16 budget, the 2016–17 budget represents a downward trend in the percentage increases of budgetary allocations for science, technology, and biotechnology, he says. “The decreasing trend in the enhanced allocations over the past two years does not augur well for a country that aspires to strengthen its emerging status as a science-driven nation,” Ganesh says.

Home > Press > FEI and ICON Analytical Demonstrate the Power of TEM for Materials and Life Sciences Research: FEI’s Talos scanning transmission electron microscope will be available for demos and workshops at the Indian Institute of Science from 23 November to 15 December 2015 Abstract: FEI (NASDAQ: FEIC) and ICON Analytical will hold workshops and demonstrations of FEI’s Talos™ scanning transmission electron microscope (STEM) at the Indian Institute of Science, Materials Research Centre in Bangalore, starting 23 November through 15 December 2015. The industry-leading Talos F200X STEM delivers high-resolution characterization data in two- and three-dimensions. Innovative integration of multiple imaging and analytical modes increases throughput and repeatability without compromising data quality. With Talos, scientists and engineers can acquire statistically meaningful sub-nm data across all research labs in industry, government and academia. “Talos is a new-generation TEM designed for multi-disciplined laboratories. Our customers will appreciate that new, advanced characterization data can be acquired rapidly and more easily with a lower level of expertise than is typical. Talos can improve productivity by providing sub-nm data to more users in less time, while also reducing training overhead,” states Anand Rao, managing director at ICON Analytical, India. To schedule a demonstration of the Talos STEM, please contact ICON Analytical: or 1.800.103.1423. For more information about the Talos TEM, please visit: About FEI Company FEI Company (Nasdaq: FEIC) designs, manufactures and supports a broad range of high-performance microscopy workflow solutions that provide images and answers at the micro-, nano- and picometer scales. Its innovation and leadership enable customers in industry and science to increase productivity and make breakthrough discoveries. Headquartered in Hillsboro, Ore., USA, FEI has over 2,600 employees and sales and service operations in more than 50 countries around the world. More information can be found at: About ICON Analytical ICON Analytical Equipment Pvt. Ltd. Is an established company in the field of analytical instruments, with a focus in “Nano Technology” and related analytical techniques. Headquartered in Mumbai, it has regional offices located in Delhi, Chennai, Bengaluru and Kolkata. For more information, please visit: FEI Safe Harbor Statement This news release contains forward-looking statements that include statements regarding the performance capabilities and benefits of the Talos STEM. Factors that could affect these forward-looking statements include but are not limited to our ability to manufacture, ship, deliver and install the tools, solutions or software as expected; failure of the product or technology to perform as expected; unexpected technology problems and challenges; changes to the technology; the inability of FEI, its suppliers or project partners to make the technological advances required for the technology to achieve anticipated results; and the inability of the customer to deploy the tools or develop and deploy the expected new applications. Please also refer to our Form 10-K, Forms 10-Q, Forms 8-K and other filings with the U.S. Securities and Exchange Commission for additional information on these factors and other factors that could cause actual results to differ materially from the forward-looking statements. FEI assumes no duty to update forward-looking statements. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Medepally B.,Ericsson AB | Mehta N.B.,Indian Institute of Science
IEEE Transactions on Wireless Communications | Year: 2010

The use of energy harvesting (EH) nodes as cooperative relays is a promising and emerging solution in wireless systems such as wireless sensor networks. It harnesses the spatial diversity of a multi-relay network and addresses the vexing problem of a relay's batteries getting drained in forwarding information to the destination. We consider a cooperative system in which EH nodes volunteer to serve as amplify-and-forward relays whenever they have sufficient energy for transmission. For a general class of stationary and ergodic EH processes, we introduce the notion of energy constrained and energy unconstrained relays and analytically characterize the symbol error rate of the system. Further insight is gained by an asymptotic analysis that considers the cases where the signal-to-noise-ratio or the number of relays is large. Our analysis quantifies how the energy usage at an EH relay and, consequently, its availability for relaying, depends not only on the relay's energy harvesting process, but also on its transmit power setting and the other relays in the system. The optimal static transmit power setting at the EH relays is also determined. Altogether, our results demonstrate how a system that uses EH relays differs in significant ways from one that uses conventional cooperative relays. © 2010 IEEE.

Rajan G.S.,India LLC | Rajan B.S.,Indian Institute of Science
IEEE Transactions on Information Theory | Year: 2010

In this paper, collocated and distributed space-time block codes (DSTBCs) which admit multigroup maximum-likelihood (ML) decoding are studied. First, the collocated case is considered and the problem of constructing space-time block codes (STBCs) which optimally tradeoff rate and ML decoding complexity is posed. Recently, sufficient conditions for multigroup ML decodability have been provided in the literature and codes meeting these sufficient conditions were called Clifford unitary weight (CUW) STBCs. An algebraic framework based on extended Clifford algebras (ECAs) is proposed to study CUW STBCs and using this framework, the optimal tradeoff between rate and ML decoding complexity of CUW STBCs is obtained for few specific cases. Code constructions meeting this tradeoff optimally are also provided. The paper then focuses on multigroup ML decodable DSTBCs for application in synchronous wireless relay networks and three constructions of four-group ML decodable DSTBCs are provided. Finally, the orthogonal frequency-division multiplexing (OFDM)-based Alamouti space-time coded scheme proposed by LiXia for a 2-relay asynchronous relay network is extended to a more general transmission scheme that can achieve full asynchronous cooperative diversity for arbitrary number of relays. It is then shown how differential encoding at the source can be combined with the proposed transmission scheme to arrive at a new transmission scheme that can achieve full cooperative diversity in asynchronous wireless relay networks with no channel information and also no timing error knowledge at the destination node. Four-group decodable DSTBCs applicable in the proposed OFDM-based transmission scheme are also given. © 2006 IEEE.

Evnin O.,Chulalongkorn University | Evnin O.,Vrije Universiteit Brussel | Krishnan C.,Indian Institute of Science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Recent investigations have revealed powerful selection rules for resonant energy transfer between modes of nonlinear perturbations in global anti-de Sitter (AdS) space-time. It is likely that these selection rules are due to the highly symmetric nature of the underlying AdS background, though the precise relation has remained unclear. In this article, we demonstrate that the equation satisfied by the scalar field mode functions in AdSd+1 has a hidden SU(d) symmetry, and explicitly specify the multiplets of this SU(d) symmetry furnished by the mode functions. We also comment on the role this structure might play in explaining the selection rules. © 2015 American Physical Society.

Dwivedi G.R.,Indian Institute of Science | Sharma E.,Indian Institute of Science | Sharma E.,Max Planck Institute for Developmental Biology | Rao D.N.,Indian Institute of Science
Nucleic Acids Research | Year: 2013

Helicobacter pylori is a Gram-negative bacterium that colonizes human stomach and causes gastric inflammation. The species is naturally competent and displays remarkable diversity. The presence of a large number of restriction-modification (R-M) systems in this bacterium creates a barrier against natural transformation by foreign DNA. Yet, mechanisms that protect incoming double-stranded DNA (dsDNA) from restriction enzymes are not well understood. A DNA-binding protein, DNA Processing Protein A (DprA) has been shown to facilitate natural transformation of several Gram-positive and Gram-negative bacteria by protecting incoming single-stranded DNA (ssDNA) and promoting RecA loading on it. However, in this study, we report that H. pylori DprA (HpDprA) binds not only ssDNA but also dsDNA thereby conferring protection to both from various exonucleases and Type II restriction enzymes. Here, we observed a stimulatory role of HpDprA in DNA methylation through physical interaction with methyltransferases. Thus, HpDprA displayed dual functional interaction with H. pylori R-M systems by not only inhibiting the restriction enzymes but also stimulating methyltransferases. These results indicate that HpDprA could be one of the factors that modulate the R-M barrier during inter-strain natural transformation in H. pylori. © The Author(s) 2013.

Sudhakara Reddy B.,Indira Gandhi Institute of Development Research | Nathan H.S.K.,Indian Institute of Science
Renewable and Sustainable Energy Reviews | Year: 2013

There is a growing consensus that universalization of modern energy services is central to reducing major elements of poverty and hunger, to increase literacy and education, and to improve health care, employment opportunities, and lives of women and children. In India, as per 2011 census, over 700 million people lack access to modern energy services for lighting, cooking, water pumping and other productive purposes. Devoid of these services people, mostly women, are forced to spend significant amounts of their time and effort on subsistence activities like firewood collection, carrying these head load for miles, and then burning these hard earned fuels inefficiently in traditional chullas. These adversely affect the health and standard of living for women and act as a barrier to gender development (here 'gender' means women unless otherwise specified). Although the links between gender inequity, poverty, and energy deprivation have been studied by many, not many practical solutions to the above problems have emerged. The present paper explores the nexus among gender-energy-poverty, highlights areas of gender concern, and suggests actions. We analyze how women from rural areas and low income households are at the receiving ends of energy poverty. We then analyze the roles women as an important stakeholders in universalizing modern energy services. We show how women self-help groups can be a vital link in large-scale diffusion of energy-efficient and renewable technologies. The paper concludes with policy pointers for sustainable development and gender empowerment through energy solutions. © 2012 Elsevier Ltd. All rights reserved.

Chakrabarty R.,University of Utah | Mukherjee P.S.,Indian Institute of Science | Stang P.J.,University of Utah
Chemical Reviews | Year: 2011

Early coordination-driven self-assembly paradigms and more complex and discrete 2D and 3D supramolecular ensembles are reviewed. Work in this field focused on the development of rational methodologies for the self-assembly of predesigned systems along with their characterization. Multinuclear, high-resolution NMR and electrospray mass spectrometry are the primary and essential tools for proper characterization along with X-ray and more recently synchrotron X-ray methods. The most recent and arguably interesting applications have been in catalysis, use as microreactors and biological applications. Raymond and Bergman have exploited the cavities of self-assembled 3D cages for enzyme-like catalysis. Coordination-driven self-assembly will continue to be an active area of research and an important component of supramolecular chemistry and nanoscience.

Donthi S.N.,Broadcom Corporation | Donthi S.N.,Indian Institute of Science | Mehta N.B.,Indian Institute of Science
IEEE Transactions on Wireless Communications | Year: 2011

The Effective Exponential SNR Mapping (EESM) is an indispensable tool for analyzing and simulating next generation orthogonal frequency division multiplexing (OFDM) based wireless systems. It converts the different gains of multiple subchannels, over which a codeword is transmitted, into a single effective flat-fading gain with the same codeword error rate. It facilitates link adaptation by helping each user to compute an accurate channel quality indicator (CQI), which is fed back to the base station to enable downlink rate adaptation and scheduling. However, the highly non-linear nature of EESM makes a performance analysis of adaptation and scheduling difficult; even the probability distribution of EESM is not known in closed-form. This paper shows that EESM can be accurately modeled as a lognormal random variable when the subchannel gains are Rayleigh distributed. The model is also valid when the subchannel gains are correlated in frequency or space. With some simplifying assumptions, the paper then develops a novel analysis of the performance of LTE's two CQI feedback schemes that use EESM to generate CQI. The comprehensive model and analysis quantify the joint effect of several critical components such as scheduler, multiple antenna mode, CQI feedback scheme, and EESM-based feedback averaging on the overall system throughput. © 2011 IEEE.

Ganesan S.,Indian Institute of Science | Tobiska L.,Otto Von Guericke University of Magdeburg
Journal of Computational Physics | Year: 2012

A finite-element scheme based on a coupled arbitrary Lagrangian-Eulerian and Lagrangian approach is developed for the computation of interface flows with soluble surfactants. The numerical scheme is designed to solve the time-dependent Navier-Stokes equations and an evolution equation for the surfactant concentration in the bulk phase, and simultaneously, an evolution equation for the surfactant concentration on the interface. Second-order isoparametric finite elements on moving meshes and second-order isoparametric surface finite elements are used to solve these equations. The interface-resolved moving meshes allow the accurate incorporation of surface forces, Marangoni forces and jumps in the material parameters. The lower-dimensional finite-element meshes for solving the surface evolution equation are part of the interface-resolved moving meshes. The numerical scheme is validated for problems with known analytical solutions. A number of computations to study the influence of the surfactants in 3D-axisymmetric rising bubbles have been performed. The proposed scheme shows excellent conservation of fluid mass and of the total mass of the surfactant. © 2012 Elsevier Inc.

Lenka N.K.,Indian Institute of Science | Lal R.,Ohio State University
Soil and Tillage Research | Year: 2012

Mulching effect on carbon (C) sequestration depends on soil properties, mulch material, and the rate and duration of application. Thus, rate of soil C sequestration was assessed on a 15 year field study involving three levels of wheat straw at 0 (M 0), 8 (M 8) and 16 (M 16) Mgha -1yr -1, at two levels (244kgNha -1yr -1, F 1 and without, F 0) of supplemental N. Soil C concentration was assessed in relation to aggregation and occlusion in aggregates of a silt loam Alfisol under a no-till (NT) and crop-free system in central Ohio. In comparison to control, soil organic carbon (SOC) concentration in the 0-10cm depth of bulk soil increased by 32% and 90% with M 8 and M 16 treatments with a corresponding increase in the SOC stock by 21-25% and 50-60%, respectively. With increase in rate of residue mulch, proportion of water stable aggregates (small macroaggregates, >250μm size) increased by 1.4-1.8 times and of microaggregates (53-250μm) by 1.4 times. Fertilizer N significantly increased the SOC concentration of small macroaggregates under M 16 treatments only. Ultra-sonication showed that 12-20% of SOC occluded in the inter-microaggregate space of small macroaggergates, was a function of both mulch and fertilizer rates. Significantly higher and positive correlation of greenhouse gases (GHGs), CO 2, CH 4 and N 2O flux was observed with C and N concentrations of small macroaggregates and also of the occluded fraction of small macroaggregates. The higher correlation coefficient indicated the latter to be prone to microbial attack. On the contrary, non-significant relationship with C and N concentrations of microaggregates indicate a possible protection of microaggregate C. The diurnal fluxes of CO 2, CH 4 and N 2O were the lowest under bare soil and the highest under high mulch rate with added N, with values ranging from 1.51 to 2.31gm -2d -1, -2.79 to 3.15mgm -2d -1 and 0.46 to 1.02mgm -2d -1, respectively. Mulch rate affected the GHGs flux more than did the fertilizer rates. The net global warming potential (GWP) was higher for high mulch (M 16) than low mulch (M 8) rates, with values ranging from 0.46 to 0.57 Mg CO 2 equivalent - Cha -1yr -1 (M 8) and 1.98 to 3.05Mg CO 2 equivalent - Cha -1yr -1 (M 16). In general, mulch rate determined the effect of fertilizers. The study indicated that over long-term, a mulch rate between 8 and 16Mgha -1yr -1 may be optimal for Alfisols in Central Ohio. © 2012 Elsevier B.V.

Shenoy V.B.,Indian Institute of Science | Ho T.-L.,Ohio State University
Physical Review Letters | Year: 2011

We generalize the Noziéres-Schmitt-Rink method to study the repulsive Fermi gas in the absence of molecule formation, i.e., in the so-called "upper branch." We find that the system remains stable except close to resonance at sufficiently low temperatures. With increasing scattering length, the energy density of the system attains a maximum at a positive scattering length before resonance. This is shown to arise from Pauli blocking which causes the bound states of fermion pairs of different momenta to disappear at different scattering lengths. At the point of maximum energy, the compressibility of the system is substantially reduced, leading to a sizable uniform density core in a trapped gas. The change in spin susceptibility with increasing scattering length is moderate and does not indicate any magnetic instability. These features should also manifest in Fermi gases with unequal masses and/or spin populations. © 2011 American Physical Society.

Nagathihalli N.S.,Vanderbilt University | Nagaraju G.,Indian Institute of Science
Biochimica et Biophysica Acta - Reviews on Cancer | Year: 2011

Chemotherapy is a very important therapeutic strategy for cancer treatment. The failure of conventional and molecularly targeted chemotherapeutic regimes for the treatment of pancreatic cancer highlights a desperate need for novel therapeutic interventions. Chemotherapy often fails to eliminate all tumor cells because of intrinsic or acquired drug resistance, which is the most common cause of tumor recurrence. Overexpression of RAD51 protein, a key player in DNA repair/recombination has been observed in many cancer cells and its hyperexpression is implicated in drug resistance. Recent studies suggest that RAD51 overexpression contributes to the development, progression and drug resistance of pancreatic cancer cells. Here we provide a brief overview of the available pieces of evidence in support of the role of RAD51 in pancreatic tumorigenesis and drug resistance, and hypothesize that RAD51 could serve as a potential biomarker for diagnosis of pancreatic cancer. We discuss the possible involvement of RAD51 in the drug resistance associated with epithelial to mesenchymal transition and with cancer stem cells. Finally, we speculate that targeting RAD51 in pancreatic cancer cells may be a novel approach for the treatment of pancreatic cancer. © 2011 Elsevier B.V.

Rotstein B.H.,University of Toronto | Rotstein B.H.,Harvard University | Zaretsky S.,University of Toronto | Rai V.,University of Toronto | And 2 more authors.
Chemical Reviews | Year: 2014

The progress made in multicomponent reactions (MCRs) that either produce small heterocycles or employ them as starting materials are investigated. Driven by strain release, multicomponent reactions employing small ring heterocycles offer opportunities for atom-economical synthesis of organic molecules. Isocyanide-based MCRs are made possible by the 1,1-amphoteric nature of the isocyanide functional group. Passerini and Ugi reactions are the two most well-known isocyanide-based MCRs. One strategy to extend MCR reactivity is to substitute one component of a known MCR with a small heterocycle. A second strategy for MCRs that employ epoxides for attack on bromonium ions is the introduction of an additional nucleophile to conduct the terminal ring opening, rather than bromide formed in situ. It is noteworthy that alternate factors can also provide the driving force, leading to opportunities to retain the core structures of small heterocycles in products. In some cases, small ring heterocycles can even be built during multicomponent synthesis.

Thakur T.S.,CSIR - Central Electrochemical Research Institute | Dubey R.,Indian Institute of Science | Desiraju G.R.,Indian Institute of Science
Annual Review of Physical Chemistry | Year: 2015

The notion of structure is central to the subject of chemistry. This review traces the development of the idea of crystal structure since the time when a crystal structure could be determined from a three-dimensional diffraction pattern and assesses the feasibility of computationally predicting an unknown crystal structure of a given molecule. Crystal structure prediction is of considerable fundamental and applied importance, and its successful execution is by no means a solved problem. The ease of crystal structure determination today has resulted in the availability of large numbers of crystal structures of higher-energy polymorphs and pseudopolymorphs. These structural libraries lead to the concept of a crystal structure landscape. A crystal structure of a compound may accordingly be taken as a data point in such a landscape. © 2015 by Annual Reviews. All rights reserved.

Vyasanakere J.P.,Indian Institute of Science | Zhang S.,Ohio State University | Shenoy V.B.,Indian Institute of Science
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We investigate the ground state of interacting spin-12 fermions in three dimensions at a finite density (ρ∼kF3) in the presence of a uniform non-Abelian gauge field. The gauge-field configuration (GFC) described by a vector λ?(λx,λy,λz) , whose magnitude λ determines the gauge coupling strength, generates a generalized Rashba spin-orbit interaction. For a weak attractive interaction in the singlet channel described by a small negative scattering length (k F|as|?1), the ground state in the absence of the gauge field (λ=0) is a BCS (Bardeen-Cooper-Schrieffer) superfluid with large overlapping pairs. With increasing gauge-coupling strength, a non-Abelian gauge field engenders a crossover of this BCS ground state to a BEC (Bose-Einstein condensate) of bosons even with a weak attractive interaction that fails to produce a two-body bound state in free vacuum (λ=0). For large gauge couplings (λ/kF?1), the BEC attained is a condensate of bosons whose properties are solely determined by the Rashba gauge field (and not by the scattering length so long as it is nonzero)-we call these bosons "rashbons." In the absence of interactions (as=0 -), the shape of the Fermi surface of the system undergoes a topological transition at a critical gauge coupling λT. For high-symmetry GFCs we show that the crossover from the BCS superfluid to the rashbon BEC occurs in the regime of λ near λT. In the context of cold atomic systems, these results make an interesting suggestion of obtaining BCS-BEC crossover through a route other than tuning the interaction between the fermions. © 2011 American Physical Society.

Srilatha N.,Indian Institute of Science | Madhavi Latha G.,Indian Institute of Science | Puttappa C.G.,MSRIT
Geotextiles and Geomembranes | Year: 2013

This paper studies the effect of frequency of base shaking on the dynamic response of unreinforced and reinforced soil slopes through a series of shaking table tests. Slopes were constructed using clayey sand and geogrids were used for reinforcing the slopes. Two different slope angles 45° and 60° were used in tests and the quantity and location of reinforcement is varied in different tests. Acceleration of shaking is kept constant as 0.3 g in all the tests to maximize the response and the frequency of shaking was 2 Hz, 5 Hz and 7 Hz in different tests. The slope is instrumented with ultrasonic displacement sensors and accelerometers at different elevations. The response of different slopes is compared in terms of the deformation of the slope and acceleration amplifications measured at different elevations. It is observed that the displacements at all elevations increased with increase in frequency for all slopes, whereas the effect of frequency on acceleration amplifications is not significant for reinforced slopes. Results showed that the acceleration and displacement response is not increasing proportionately with the increase in the frequency, suggesting that the role of frequency in the seismic response is very important. Reinforced slopes showed lesser displacements compared to unreinforced slopes at all frequency levels. © 2012 Elsevier Ltd.

Rayasam G.V.,CSIR - Central Electrochemical Research Institute | Balganesh T.S.,Indian Institute of Science
Trends in Pharmacological Sciences | Year: 2015

host-directed need for treatment of drug-resistant tuberculosis (TB) is to find novel therapies that are efficacious, safe, and shorten the duration of treatment. Drug discovery approaches for TB primarily target essential genes of the pathogen Mycobacterium tuberculosis (Mtb) but novel strategies such as host-directed therapies and nonmicrobicidal targets are necessary to bring about a paradigm shift in treatment. Drugs targeting the host pathways and nonmicrobicidal proteins can be used only in conjunction with existing drugs as adjunct therapies. Significantly, host-directed adjunct therapies have the potential to decrease duration of treatment, as they are less prone to drug resistance, target the immune responses, and act via novel mechanism of action. Recent advances in targeting host-pathogen interactions have implicated pathways such as eicosanoid regulation and angiogenesis. Furthermore, several approved drugs such as metformin and verapamil have been identified that appear suitable for repurposing for the treatment of TB. These findings and the challenges in the area of host- and/or pathogen-directed adjunct therapies and their implications for TB therapy are discussed. © 2015 Elsevier Ltd.

McConkey K.R.,Indian Institute of Science | O'Farrill G.,University of Toronto
Trends in Ecology and Evolution | Year: 2015

The essential functional roles performed by animal species are lost when they become locally extinct, and ecosystems are critically threatened by this decline in functional diversity. Theory that links function, diversity, and ecosystem stability exists but fails to assess function loss that occurs in species with persistent populations. The entire functional role of a species, or a critical component of it, can be lost following large population declines (functional extinction), following population increase, or after behavioural adaptations to changes in the population, community, habitat, or climate. Here, we provide a framework that identifies the scenarios under which 'cryptic' function loss can occur in persistent populations. Cryptic function loss is potentially widespread and critically threatens ecosystem stability across the globe. © 2015 Elsevier Ltd.

Garg A.,Saha Institute of Nuclear Physics | Krishnamurthy H.R.,Indian Institute of Science | Randeria M.,Ohio State University
Physical Review Letters | Year: 2014

We demonstrate in a simple model the surprising result that turning on an on-site Coulomb interaction U in a doped band insulator leads to the formation of a half-metallic state. In the undoped system, we show that increasing U leads to a first order transition at a finite value UAF between a paramagnetic band insulator and an antiferomagnetic Mott insulator. Upon doping, the system exhibits half-metallic ferrimagnetism over a wide range of doping and interaction strengths on either side of UAF. Our results, based on dynamical mean field theory, suggest a new route to half metallicity, and will hopefully motivate searches for new materials for spintronics. © 2014 American Physical Society.

Khare A.,Indian Institute of Science | Saxena A.,Los Alamos National Laboratory
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2013

We demonstrate a kind of linear superposition for a large number of nonlinear equations which admit elliptic function solutions, both continuum and discrete. In particular, we show that whenever a nonlinear equation admits solutions in terms of Jacobi elliptic functions cn(x,m) and dn(x,m), then it also admits solutions in terms of their sum as well as difference, i.e. dn(x,m)±mcn(x,m). Further, we also show that whenever a nonlinear equation admits a solution in terms of dn2(x,m), it also has solutions in terms of dn2(x,m)±mcn(x,m)dn(x,m) even though cn(x,m)dn(x,m) is not a solution of that nonlinear equation. Finally, we obtain similar superposed solutions in coupled theories. © 2013 Elsevier B.V.

Madhavan R.,Indian Institute of Science | Ray R.K.,Tata Steel | Suwas S.,Indian Institute of Science
Acta Materialia | Year: 2014

The micromechanical aspects of rolling texture development in Ni-40 wt.% Co alloy during very large reductions (up to εt = 3.9) have been studied. The alloy showed a typical Cu-type texture up to a true strain of εt = 3; however, the texture undergoes an abrupt transition to Bs-type on further rolling to εt ≈ 4. (The Bs-type texture, here, comprises almost equal fractions of Goss and Bs components.) Microstructural observations, at early stages, show that deformation is accommodated entirely by slip, and very little presence of deformation twinning is observed to explain the texture transition. However, at much higher reduction levels, micrographs show a high fraction of Cu-type shear bands. These bands are predominantly found in Cu-oriented grains and the crystallites inside the shear bands are preferentially oriented towards Goss, which could explain the final texture evolution. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Malinowski M.,Warsaw University of Technology | Gopakumar K.,Indian Institute of Science | Rodriguez J.,Federico Santa María Technical University | Perez M.A.,Federico Santa María Technical University
IEEE Transactions on Industrial Electronics | Year: 2010

Cascaded multilevel inverters synthesize a medium-voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. Due to these features, the cascaded multilevel inverter has been recognized as an important alternative in the medium-voltage inverter market. This paper presents a survey of different topologies, control strategies and modulation techniques used by these inverters. Regenerative and advanced topologies are also discussed. Applications where the mentioned features play a key role are shown. Finally, future developments are addressed. © 2010 IEEE.

Rashmi K.V.,Indian Institute of Science | Shah N.B.,Indian Institute of Science | Kumar P.V.,Indian Institute of Science | Kumar P.V.,University of Southern California
IEEE Transactions on Information Theory | Year: 2011

Regenerating codes are a class of distributed storage codes that allow for efficient repair of failed nodes, as compared to traditional erasure codes. An [n, k, d] regenerating code permits the data to be recovered by connecting to any k of the n nodes in the network, while requiring that a failed node be repaired by connecting to any d nodes. The amount of data downloaded for repair is typically much smaller than the size of the source data. Previous constructions of exact-regenerating codes have been confined to the case n=d+1. In this paper, we present optimal, explicit constructions of (a) Minimum Bandwidth Regenerating (MBR) codes for all values of [n, k, d] and (b) Minimum Storage Regenerating (MSR) codes for all [n, k, d ≥ 2k-2], using a new product-matrix framework. The product-matrix framework is also shown to significantly simplify system operation. To the best of our knowledge, these are the first constructions of exact-regenerating codes that allow the number n of nodes in the network, to be chosen independent of the other parameters. The paper also contains a simpler description, in the product-matrix framework, of a previously constructed MSR code with [n=d+1, k, d ≥ 2k-1]. © 2011 IEEE.

Diastereoselective self-assembly of Zn(ii) heterochiral complexes of racemic Schiff bases L1H and L2H (where L1H = 2-((phenyl(2-pyridyl)methylimino)- methyl)phenol; L2H = 1-((phenyl(2-pyridyl)methylimino)methyl)-2-naphthol) in a chiral self-discriminating process are reported. Complexes 1-6 are synthesized using ligand L1H (1-3), L2H (4-6), Zn(NO3)2·6H 2O, and co-ligands such as N3 - or NCS - and are conclusively structurally characterized. Determination of molecular structures of 1-5 confirmed the presence of a di-metallic core constructed by monochelated tridentate ligands with an inversion centre located directly between the two zinc ions. In 1-5, within one centrosymmetric dimer one of the ligands possessed R configuration whereas other possessed S configuration resulting a heterochiral dimerization of ligands around the Zn(ii) centre in a chiral self-discriminating manner. Complex 6 is mononuclear having R configuration of ligand L2 and linked through a C-H⋯O interaction with the nearby mononuclear Zn(ii) centre having S configuration of ligand L2 and consequently a heterochiral dimer. The plausible mechanism for the chiral self-discrimination is revealed which makes it clear that trans oriented anions direct the phenyl group appended to the asymmetric carbon atoms to be trans due to steric congestion and consequently the heterochiral dimerization configuration. The effects of different non-covalent interactions to self-assemble the heterochiral dimers to 1D chain having the sequence ⋯RS⋯RS⋯RS⋯ or ⋯RS⋯SR⋯RS⋯ or ⋯R⋯S⋯R⋯ and to transfer the stereochemical information of the heterochiral dimers throughout the chain are studied. Also the effects of the anions on the isotactic and syndiotactic arrangements of coordination complex are studied. The results demonstrate that ligand modification, anions and non-covalent interactions play a domino role on controlling the solid state structural rearrangements and photoluminescence properties of the synthesized complexes. © 2014 The Royal Society of Chemistry.

Sinha S.,Indian Institute of Science | Nath R.,Max Planck Institute for the Physics of Complex Systems | Santos L.,Leibniz University of Hanover
Physical Review Letters | Year: 2011

We study trapped 2D atomic Bose-Einstein condensates with spin-independent interactions in the presence of an isotropic spin-orbit coupling, showing that a rich physics results from the nontrivial interplay between spin-orbit coupling, confinement and interatomic interactions. For low interactions two types of half-vortex solutions with different winding occur, whereas strong-enough repulsive interactions result in a stripe-phase similar to that predicted for homogeneous condensates. Intermediate interaction regimes are characterized for large enough spin-orbit coupling by an hexagonally-symmetric phase with a triangular lattice of density minima similar to that observed in rapidly rotating condensates. © 2011 American Physical Society.

Tomar D.,Indian Institute of Science | Tomar D.,University of Bordeaux 1 | Singh R.,M. S. University of Baroda
Biology of the Cell | Year: 2015

The nuclear factor κB (NF-κB) transcription factor family plays a key role in regulation of the inflammatory pathway in response to different physiological stimuli starting from development to ageing. The dysregulation of NF-κB has been associated with many pathological conditions like inflammatory diseases, neurodegeneration, metabolic diseases and various kinds of malignancies. The NF-κB pathway is regulated by number of post-translational modifications, including phosphorylation and ubiquitination. Ubiquitin (Ub) E3 ligases are key regulators of the process of ubiquitination and provide specificity to the pathway as they recognise the substrate and determine the topology of ubiquitination. TRIMs, members of RING family of Ub E3 ligases, are characterised by the presence of three conserved domains, RING, B-Box and coiled-coil (RBCC). Emerging evidence suggests that TRIMs regulate innate immune signalling during infection and different pathological conditions. The studies have demonstrated the role of TRIMs in regulation of inflammatory pathways including NF-κB. Recent reports suggest that TRIMs play a critical role in regulation of the NF-κB pathway by ubiquitinating proteins at different steps. In the current review, we discuss the role of TRIMs as novel NF-κB regulators and their role in different pathophysiological conditions. © 2014 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

Mehta N.B.,Indian Institute of Science | Kashyap S.,Indian Institute of Science | Molisch A.,University of Southern California
IEEE Communications Magazine | Year: 2012

Transmit antenna selection technology has been adopted for the uplink by the next generation Long Term Evolution wireless standard in order to harness the spatial diversity offered by multiple antennas at the mobile transmitter, while keeping the hardware complexity and cost of a mobile low. In TAS, the number of RF chains for processing/up-conversion is smaller than the number of available antenna elements, so at any time the signals can only be transmitted from a (dynamically optimized) subset of antenna elements. As a result, the training procedure for AS needs to be carefully engineered. In LTE, this is accomplished by reusing the wideband sounding reference signal for the purpose of AS training. Furthermore, new mechanisms are required to facilitate feedback from the receiver (the base station) to the transmitter about which subset is optimal and should thus be used by the mobile. In LTE, this is accomplished by employing a unique masking technique on the downlink control channel that eliminates the feedback overhead at the expense of a minor increase in complexity at the mobile. This article provides an in-depth and systematic overview of all physical and higher layer features in the LTE standard that enable TAS. Also highlighted are the variety of technical and standardization challenges that drove the specification of AS in LTE, and the aspects of the LTE standard that are impacted by AS. © 2012 IEEE.

Ghosh D.,Indian Institute of Science | Ghanem R.,University of Southern California
International Journal for Numerical Methods in Engineering | Year: 2012

The repeated or closely spaced eigenvalues and corresponding eigenvectors of a matrix are usually very sensitive to a perturbation of the matrix, which makes capturing the behavior of these eigenpairs very difficult. Similar difficulty is encountered in solving the random eigenvalue problem when a matrix with random elements has a set of clustered eigenvalues in its mean. In addition, the methods to solve the random eigenvalue problem often differ in characterizing the problem, which leads to different interpretations of the solution. Thus, the solutions obtained from different methods become mathematically incomparable. These two issues, the difficulty of solving and the non-unique characterization, are addressed here. A different approach is used where instead of tracking a few individual eigenpairs, the corresponding invariant subspace is tracked. The spectral stochastic finite element method is used for analysis, where the polynomial chaos expansion is used to represent the random eigenvalues and eigenvectors. However, the main concept of tracking the invariant subspace remains mostly independent of any such representation. The approach is successfully implemented in response prediction of a system with repeated natural frequencies. It is found that tracking only an invariant subspace could be sufficient to build a modal-based reduced-order model of the system. © 2012 John Wiley & Sons, Ltd.

An international team of scientists with participation from the University of Göttingen, the Indian Institute of Science, Bangalore, Pennsylvania State University, and Wright State University has measured the mechanics of tiny crystalline ceramics. Materials are made of atoms, and if they are arranged periodically, they are called crystalline structures. If the size of these crystalline structures is 1,000 times smaller than a single human hair diameter, then they are called nano-structures such as nano-rods, nano-wires, nano-ribbons, nano-belts etc. In some cases, special atomic arrangements enable them to convert mechanical energy into electrical energy. These materials are called piezoelectric materials. They are useful for energy harvesting as well as a variety of electro-mechanical gadgets to enhance the quality of life. Hence, it is important to have a grip on these nano-structures and measure their mechanical responses. Until now, it was unknown that mechanical behavior of piezoelectric nano-crystals containing atomic defects is different than pure. This recent study is reported in the journal Nano Letters.

Malik R.P.,BHU Varanasi | Khare A.,Indian Institute of Science
Annals of Physics | Year: 2013

We demonstrate the existence of a novel set of discrete symmetries in the context of the N=2 supersymmetric (SUSY) quantum mechanical model with a potential function f(x) that is a generalization of the potential of the 1D SUSY harmonic oscillator. We perform the same exercise for the motion of a charged particle in the X-Y plane under the influence of a magnetic field in the Z-direction. We derive the underlying algebra of the existing continuous symmetry transformations (and corresponding conserved charges) and establish its relevance to the algebraic structures of the de Rham cohomological operators of differential geometry. We show that the discrete symmetry transformations of our present general theories correspond to the Hodge duality operation. Ultimately, we conjecture that any arbitrary N=2 SUSY quantum mechanical system can be shown to be a tractable model for the Hodge theory. © 2013 Elsevier Inc.

Mandal S.K.,Indian Institute of Science | Roesky H.W.,University of Gottingen
Chemical Communications | Year: 2010

Interstellar space is among the most remarkable chemical laboratories in the universe. The existence of many unstable species with low-valent main group elements in the interstellar medium inspired us to investigate the feasibility of laboratory synthesis of such unstable molecules. Particularly the lighter Group 14 element carbon plays a very important role in space astrochemistry. Low-valent carbon as well as silicon were detected in the interstellar environment. This article describes our recent efforts in developing amazing chemistry of heavier low-valent Group 14 elements. This study unravels that the disproportionation pathway of the low-valent Group 14 elements can be arrested by using a sterically protected ligand, then one can artificially generate the situation observed in the interstellar surrounding where the chance of disproportionation is very low as the molecules are extremely dilute. © 2010 The Royal Society of Chemistry.

Mandal S.K.,Indian Institute of Science | Roesky H.W.,University of Gottingen
Accounts of Chemical Research | Year: 2010

(Figure Presented) Assembling a molecule containing two metal centers with entirely different chemical properties remains a synthetic challenge. One of the major motivations for this chemistry is its ability to catalyze various organic transformations. The proximity between two different metals in a heterometallic complex allows more pronounced chemical communication between the metals and often leads to the modification of the fundamental properties of the individual metal atoms through the well-known cooperative interaction. Although various types of heterometallic systems are known, the M-O-M' framework is particularly important because it brings the metals into close proximity with each other. In this Account, we describe several suitable synthetic routes for the assembly of heterometals of entirely different chemical properties through an oxygen atom. The new synthetic strategies for the construction of heterobimetallic complexes take advantage of unprecedented syntheses of a number of hydroxide precursors of the type LMR(OH) [L = CH{N(Ar)(CMe)}2, Ar = 2,6-iPr 2C6H3; M = Al, Ga, or Ge; R = alkyl, aryl, or lone pair of electrons], [LSr(μ-OH)]2 · (THF)3, and Cp*2ZrMe(OH). We used the Brønsted acidic character of the proton in the M(O-H), Sr(O-H), or Zr(O-H) moiety, to build a new class of heterobimetallic complexes based on M-O-M' motif. This synthetic strategy assembles a main group element with another main group element, a transition metal, or a lanthanide metal. This synthetic development provides access to a new class of heterobimetallic complexes through oxygen bridging. In many cases these complexes prove to be excellent candidates for polymerization of monomers including ε-caprolactone, ethylene, and styrene. Some of these catalysts bear a chemically grafted methylalumoxane (MAO) unit in the backbone of an active metal center, which led to efficient ethylene polymerizations at an unusually low MAO concentration. We attribute this reactivity both to the presence of a chemically grafted (Me)Al-O backbone in the active catalysts (a part of externally added cocatalyst, MAO) and to the enhanced Lewis acidity from the bridging oxygen at the active metal center. In addition, we have demonstrated the development of heterometallic systems having two catalytically active centers. Such structures could aid in the development of a catalytic system bearing two active centers with different chemistries. © 2010 American Chemical Society.

News Article | October 30, 2015

This is a photothermal deflection spectrometer (PDS) and the mirage – only the width of a human hair in distance from the glass – is helping researchers to measure the quality of materials that turn light energy into electricity. "We can see one defect in a million molecules," explains Sadhanala, who built the machine while working on his PhD in the lab of Professor Sir Richard Friend. "The PDS technique measures the amount of light absorbed by a material with up to five orders of magnitude more sensitivity than conventional techniques, making it one of the most sensitive absorption spectrometers in the world." A mirage is formed as light is bent when it passes through a medium with varying refractive index – a puddle of water seems to appear on the road ahead, for instance, when light meets hotter air radiating from the ground on a sunny day. Sadhanala's machine creates a mirage effect when light absorbed by the solar material is released as heat, which passes to a liquid that surrounds the sample. When a laser beam is directed to pass parallel to it, the mirage deflects the beam; the amount of deflection corresponds to the amount of heat absorbed, which in turn corresponds to the amount of light absorbed. "Before, we would have had to make a whole solar device and spend months and months testing it to find out how efficient the material is," explains Sadhanala. "Now you can measure a new material in half a day, and you don't even need to make the whole device – you just need to be able to coat the material onto glass and make a mirage." A few weeks ago, Tushita Mukhopadhyay – a chemist at the Indian Institute of Science, Bangalore – carefully packaged up five new materials and flew to the UK to test them on the 'mirage machine' in Cambridge, and analyse other properties with researchers at Imperial College London. She had spent months making and characterising the materials – all of them belonging to a group of organic solar cells (OSCs) that can be printed as thin-film sheets. What connects the two researchers, and indeed many other chemists, physicists and engineers, is the APEX project – an ambitious Anglo-Indian initiative to turn fundamental advances in solar materials into commercial reality. APEX involves research institutes in Bangalore, Delhi, Hyderabad, Kanpur and Pune in India, and Brunel (which leads the partnership), Cambridge, Edinburgh, Imperial, Swansea and Oxford in the UK, plus solar industries in both countries. It has received almost £6 million funding since 2010 from the Indian Department of Science and Technology and Research Councils UK. "Solar has always been the eventual solution to our energy problems but it's always been the day after tomorrow," explains Friend, who leads the Cambridge component. "Each of the partners in this project has an extensive research programme aimed at developing highly efficient photovoltaic devices, but there is a disconnect between what you can do in the lab and what can be rolled out at huge scale. This project is aimed at moving from established science to a viable technology." First though, there is the matter of achieving a major cost reduction and efficiency increase in solar power. The APEX team started by focusing on developing a new class of 'excitonic' solar cell (which produces electricity from the sun's energy through the creation of an 'exciton' – essentially a free electron). Instead of using the conventional solar material, silicon, the researchers used solar materials made from organic dyes – dye-sensitised solar cells (DSSCs) – which are easy to make, easy to process and cost less. However, one of the main issues surrounding the search for alternative solar materials to silicon has been their power conversion efficiencies (PCEs) – the amount of the sun's energy that can be trapped and turned into electricity. The PCE for silicon is around 25%, whereas the current state-of-the-art PCE figures for DSSCs and OSCs are a little over 10%. To achieve incremental boosts in these figures, researchers like those in Friend's group have been analysing what happens at the nanoscale when light hits the material. For instance, they now know that manipulating the 'spin' of electrons in solar cells can dramatically improve their performance. Mukhopadhyay, who travelled to the UK thanks to funding through the UK–India Education and Research Initiative, explains: "My materials have a fast charge transport rate – as we've now proved at Cambridge and Imperial – but they have a low PCE. We think that a process called singlet fission, in which one exciton splits into two, is happening. This makes them interesting to look at because if more than one charge carrier is generated then this can increase the PCE." Another family of materials the team has high hopes for is a set of perovskite-structure lead halides. Work at the University of Oxford has already achieved a PCE of above 17% for such materials, and Sadhanala has begun using his machine to see the effect of different processing methods on their properties. As well as developing cheap, high-performing solar materials, the team will scale up towards prototypes that replicate the performance achieved in the research phase. Although the aim is to provide a technology that can reduce the carbon footprint of electricity generation anywhere in the world, solar energy could fulfil a massive demand for energy in India. India is the fifth largest producer and consumer of electricity, around 70% of which is based on coal, yet around 200 million people are without access to electricity. With a rapidly growing economy and more than 1 billion people, India faces a huge energy challenge to meet the current government's mission of 'Power for all, 24x7, by 2019'. In fact, India could be an ideal place to adopt new solar technologies on a large scale, says Friend: "India is already currently running the largest renewable capacity expansion programme in the world, and there is a sense that the next technology revolutions may well happen in an emerging country like India that hasn't already built its future renewables-heavy electricity system." "India may well leapfrog the UK in taking up radical new approaches to power generation," he adds. "We want APEX to contribute to the search for such approaches now and in the future. This is a journey, not a day's outing." Explore further: Reshaping the solar spectrum to turn light to electricity

Banerjee N.,Indian Institute of Technology Kharagpur | Sharma P.,Indian Institute of Science
Monthly Notices of the Royal Astronomical Society | Year: 2014

We study the interplay between turbulent heating, mixing, and radiative cooling in an idealized model of cool cluster cores. Active galactic nuclei (AGN) jets are expected to drive turbulence and heat cluster cores. Cooling of the intracluster medium (ICM) and stirring by AGN jets are tightly coupled in a feedback loop. We impose the feedback loop by balancing radiative cooling with turbulent heating. In addition to heating the plasma, turbulence also mixes it, suppressing the formation of cold gas at small scales. In this regard, the effect of turbulence is analogous to thermal conduction. For uniform plasma in thermal balance (turbulent heating balancing radiative cooling), cold gas condenses only if the cooling time is shorter than the mixing time. This condition requires the turbulent kinetic energy to be ≳ the plasma internal energy; such high velocities in cool cores are ruled out by observations. The results with realistic magnetic fields and thermal conduction are qualitatively similar to the hydrodynamic simulations. Simulations where the runaway cooling of the cool core is prevented due to mixing with the hot ICM show cold gas even with subsonic turbulence, consistent with observations. Thus, turbulent mixing is the likely mechanism via which AGN jets heat cluster cores. The thermal instability growth rates observed in simulations with turbulence are consistent with the local thermal instability interpretation of cold gas in cluster cores. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Kumar J.,Indian National Institute for Interdisciplinary Science and Technology | Thomas K.G.,Indian National Institute for Interdisciplinary Science and Technology | Thomas K.G.,Indian Institute of Science
Journal of Physical Chemistry Letters | Year: 2011

Raman signal enhancement of two analyte molecules, containing bipyridine and phenyl moieties, were investigated by linking them (i) onto the edges of Au nanorods using monothiol derivatives and (ii) at the junctions of two Au nanorods using dithiol derivatives. Edges of Au nanorods are regions of high electric field, and specific interaction of the thiol molecules on the {111} planes at the edges resulted in an enhanced Raman signal. When two Au nanorods are brought together in a linear fashion through dithiol linkages, their longitudinal plasmon oscillations couple each other, creating regions of enhanced electric field (hot spots) at the junctions. Interestingly, dimerization leads to a spontaneous enhancement in the intensity of Raman signals (enhancement factor of ∼1.4 × 10 5) due to the localization of molecules at the junctions of Au nanorod dimers. © 2011 American Chemical Society.

Banerjee J.,Indian Institute of Science | Nilsen-Hamilton M.,Iowa State University
Journal of Molecular Medicine | Year: 2013

Aptamers are single-stranded oligonucleotides that fold into well-defined three-dimensional shapes, allowing them to bind their targets with high affinity and specificity. They can be generated through an in vitro process called "Systemic Evolution of Ligands by Exponential Enrichment" and applied for specific detection, inhibition, and characterization of various targets like small organic and inorganic molecules, proteins, and whole cells. Aptamers have also been called chemical antibodies because of their synthetic origin and their similar modes of action to antibodies. They exhibit significant advantages over antibodies in terms of their small size, synthetic accessibility, and ability to be chemically modified and thus endowed with new properties. The first generation of aptamer drug "Macugen" was available for public use within 25 years of the discovery of aptamers. With others in the pipeline for clinical trials, this emerging field of medical biotechnology is raising significant interest. However, aptamers pose different problems for their development than for antibodies that need to be addressed to achieve practical applications. It is likely that current developments in aptamer engineering will be the basis for the evolution of improved future bioanalytical and biomedical applications. The present review discusses the development of aptamers for therapeutics, drug delivery, target validation and imaging, and reviews some of the challenges to fully realizing the promise of aptamers in biomedical applications. © 2013 Springer-Verlag Berlin Heidelberg.

Mukherjee R.,Ecole Polytechnique Federale de Lausanne | Chatterji D.,Indian Institute of Science
IUBMB Life | Year: 2012

Species of opportunistic mycobacteria are the major causative agent for disseminating pulmonary infections in immuno-compromised individuals. These naturally resistant strains recruit a unique type of glycolipid known as glycopeptidolipids (GPLs), noncovalently attached to the outer surface of their thick lipid rich cell envelope. Species specific GPLs constitute the chemical determinants of most nontuberculous mycobacterial serotypes, and their absence from the cell surface confers altered colony morphology, hydrophobicity, and inability to grow as biofilms. The objective of this review is to present a comprehensive account and highlight the renewed interest on this much neglected group of pleiotropic molecules with respect to their structural diversity and biosynthesis. In addition, the role of GPLs in mycobacterial survival, both intracellular and in the environment is also discussed. It also explores the possibility of identifying new targets for intervening Mycobacterium avium complex-related infections. These antigenic molecules have been considered to play a pivotal role in immune suppression and can also induce various cytokine mediated innate immune responses, the molecular mechanism of which remains obscure. Copyright © 2012 Wiley Periodicals, Inc.

Anilkumar P.,Indian National Institute for Interdisciplinary Science and Technology | Jayakannan M.,Indian Institute of Science
Journal of Physical Chemistry B | Year: 2010

We report a unique supramolecular organogel template approach for conducting polyaniline nanomaterials. A novel organogel based on sulfonic acid dopant was designed and developed from renewable resource 3-pentadecyl phenol via ring-opening of 1, 4-butane sultone. The amphiphilic dopant molecule formed thermoreversible supramolecular organogel in highly polar solvents like alcohols. The self-assembled fibril network morphology of the gel was confirmed by scanning electron microscopy (SEM) and atomic force microscopy. Transmission electron microscopy (TEM) revealed that the inner part of the fibrous gel is nanotubular with the pore diameter of ∼75 nm. The organogel nanotubular morphology was retained even in the presence of aniline+dopant complex, and the aniline monomers occupied the hydrophobic nanopockets provided by the amphiphilic dopant. The chemical oxidative polymerization of the dopant+aniline organogel template produced well-defined polyaniline nanofibers. The polymerization was carried out at various temperatures to establish the role of the physical state and stability of the organogel on the morphology. The sulfonic acid molecule acts both as self-assembled molecular template for the synthesis of polymer nanomaterial as well as anionic counterpart for stabilizing the positively charged conducting polymer chains. The gel template played a pivotal role in directing polyaniline chains to form nanofibers and also manipulating the number of other properties such as conductivity, solubility, percent crystallinity, and solid-state ordering, etc. Temperature-dependent electrical conductivity measurements revealed that the nanomaterials showed typical linear ohmic behavior and also followed the 3-D VRH model at elevated temperatures. © 2010 American Chemical Society.

Antony M.J.,Indian National Institute for Interdisciplinary Science and Technology | Jayakannan M.,Indian Institute of Science
Journal of Physical Chemistry B | Year: 2010

Here, we report a unique molecular template approach, for the first time, to study the evolution of the different types of nanomaterial morphologies such as nanofiber, nanorod, nanosphere, and nanotube in a single system without changing their chemical composition or polymerization route. A renewable resource surfactant was self-organized with aniline (95%) and pyrrole (5%) in water to produce white emulsion consisting of longrange cylindrical micellar aggregates. The dilution of the emulsion with water resulted in the transformation of cylindrical to vesicular aggregates without any phase separation. The size and shape of the cylindrical and vesicular template aggregates were confirmed by dynamic light scattering and electron microscopic analysis. The chemical oxidation of the cylindrical templates produced nanofibers and nanorods, whereas hollow spheres and nanotubes were produced by vesicular templates. The nanofibers were found as long as 4-5 μm length with 200 nm widths, whereas the nanorods were shorter in length (0.5-0.7 μm) with 80-120 nm diameter. The hollow spheres were obtained in 1 μm diameter with wall thickness of ∼80 nm. The length of the nanotubes was found to vary from 1.2 to 1.8 μm. The average wall thickness and inner pore diameter of the nanotubes were found as ∼30 nm and ∼60 nm, respectively. The size and shape of the template aggregates match very well with that of the synthesized nanomaterials and provide direct evidence for the template-assisted evolution of the nanostructure morphology. NMR, FT-IR and UV-visible spectroscopies were utilized to confirm the structure and electronic properties of the nanomaterials. Wide angle X-ray diffraction and transmission electron microscopy-electron diffraction analysis revealed that the nanotubes possessed three-dimensional lamellartype solid states ordering with high percent crystallinity up to 60%. Variable temperature four-probe conductivity measurements of all samples showed typical I- V plots. The conductivity of the nanofibers was found one order higher than that of nanorod, hollow sphere, and nanotubes at all temperatures. The present investigation enabled us to establish the role of various types of nanomorphologies on properties of nanomaterials such as conductivity and solid state ordering without change in their chemical composition © 2010 American Chemical Society.

Antony M.J.,Indian National Institute for Interdisciplinary Science and Technology | Jayakannan M.,Indian Institute of Science
Langmuir | Year: 2011

Biologically important analytes such as cysteine and vitamin-C were detected by electron transfer (ET) via naked eye colorimetric sensing using a tailor-made watersoluble vself-doped polyaniline (PSPANa) as a substrate. Monomer (N-3-sulfopropylaniline) was synthesized via ring-opening of propane sultone with excess aniline and polymerized in water using ammoniumpersulfate to obtain green water-soluble polymer. Vitamin-C (ascorbic acid) and cysteine showed unexpected sharp and instantaneous color change from blue to colorless sensing action. The stoichiometry of the analyte to polymer was determined as 3:2 and 4:1 with association (or binding) constants of K = 2.1 × 10 3 and 1.5 × 103 M-1 for vitamin-C and cysteine, respectively. Efficient electron transfer from vitamin-C (also cysteine) to the quinoid unit of the polyaniline base occurred in solution; as a result, the color of the solution changed from deep blue to colorless. Cyclic voltammetry analysis of PSPANa showed the disappearance of the cathodic peak at -0.21 V upon the addition of analytes (vitamin-C and cysteine) and confirms the electron transfer from the analyte to the polymer backbone. Dynamic light scattering (DLS) and zeta potential techniques were utilized to trace the molecular interactions in the electron transfer process. DLS histograms of the polymer samples confirmed the existence of nanoaggregates of 8-10 nm in diameter. The polymers possessed typical amphiphilic structure to produce micellar aggregates which facilitate the efficient electron transfer occurred between the analyte and polyaniline backbone. © 2011 American Chemical Society.

Kashyap N.,Indian Institute of Science | Zemor G.,Institut Universitaire de France
IEEE Transactions on Information Theory | Year: 2014

In this paper, we revisit the combinatorial error model of Mazumdar et al. that models errors in high-density magnetic recording caused by lack of knowledge of grain boundaries in the recording medium. We present new upper bounds on the cardinality/rate of binary block codes that correct errors within this model. All our bounds, except for one, are obtained using combinatorial arguments based on hypergraph fractional coverings. The exception is a bound derived via an information-theoretic argument. Our bounds significantly improve upon existing bounds from the prior literature. © 2014 IEEE.

News Article | August 22, 2016

Crystalline materials, like diamonds or gemstones, are typically hard and brittle. But crystals made of orderly arrangements of organic molecules can be flexible. Although most such crystals have been discovered serendipitously, now researchers have designed organic molecules that form flexible crystals through weak interactions between repeating building blocks (J. Am. Chem. Soc. 2016, DOI: 10.1021/jacs.6b05118). This design principle could be applied to engineer materials for organic solar cells and light-emitting diodes, or as additives to ease pharmaceutical manufacturing, the researchers say. Little is known about how the structure of organic crystals determines their mechanical properties. But C. Malla Reddy of the Indian Institute of Science Education & Research Kolkata and his colleagues started with one known principle: Under mechanical stress, weak connections easily break and reform, sometimes allowing a material to bend without breaking. Harnessing the power of weak interactions, they designed three classes of organic molecules to form different flexible crystals. One such class used building blocks of naphthalene diimides with spherical methyl or t-butyl groups on either end. The aromatic rings in the center of each building block stack one on top of the other to form one dimension of the crystal. Meanwhile, these stacks interact side-to-side through weak, short-lived electrostatic attractions between the alkyl groups. These interactions create planes running through the crystal where the layers can slide past each other when the crystal is bent. Reddy compares this sliding motion to sheets of paper slipping past each other in a bent notepad. Using this flexibility, the researchers could shape the microscopic crystals into letters of the alphabet. For the second class of molecules, the researchers used substituted benzoic acid building blocks held together in one direction with relatively strong hydrogen bonds, commonly used for linking building blocks in crystal engineering. In the other dimension, weak halogen-halogen interactions between chlorine or bromine atoms at the ends of these building blocks created the slipping layers that produced flexibility within this crystal. The researchers made the third class of building blocks out of o-vanillin joined to anilines substituted with halogens or alkoxy groups. This class of molecules forms crystals that change color when illuminated or that propel themselves off a surface when heated—properties that could be useful for applications like optical memory or mechanically active materials. In this case, weak interactions between alkoxy and halogen groups created the slip. A lot of chemical insight is required to produce crystals that can be bent into letters, says Gautam R. Desiraju of the Indian Institute of Science. He calls this an “ideal study” of crystal engineering, in that the researchers used their understanding of how the molecules in a crystal affect its structure and physical properties to design and build the crystal. Reddy hopes other researchers apply weak interactions to designing flexible organic semiconducting molecules or substances to aid pharmaceutical production. When making medicines, active ingredients are often combined with excipient materials as part of the formulation and manufacturing process. But if an excipient makes a powder too brittle, it can break when stirred, creating inconsistent product. Flexible crystals could help solve this problem, Reddy says.

Donthi S.N.,Broadcom Communications Technologies Private Ltd | Mehta N.B.,Indian Institute of Science
IEEE Transactions on Vehicular Technology | Year: 2011

Frequency-domain scheduling and rate adaptation enable next-generation orthogonal frequency-division multiple access (OFDMA) cellular systems such as Long-Term Evolution (LTE) to achieve significantly higher spectral efficiencies. LTE uses a pragmatic combination of several techniques to reduce the channel-state feedback that is required by a frequency-domain scheduler. In the subband-level feedback and user-selected subband feedback schemes specified in LTE, the user reduces feedback by reporting only the channel quality that is averaged over groups of resource blocks called subbands. This approach leads to an occasional incorrect determination of rate by the scheduler for some resource blocks. In this paper, we develop closed-form expressions for the throughput achieved by the feedback schemes of LTE. The analysis quantifies the joint effects of three critical components on the overall system throughput-scheduler, multiple-antenna mode, and the feedback schemeand brings out its dependence on system parameters such as the number of resource blocks per subband and the rate adaptation thresholds. The effect of the coarse subband-level frequency granularity of feedback is captured. The analysis provides an independent theoretical reference and a quick system parameter optimization tool to an LTE system designer and theoretically helps in understanding the behavior of OFDMA feedback reduction techniques when operated under practical system constraints. © 2010 IEEE.

Kurapati R.,Indian Institute of Science | Raichur A.M.,Indian Institute of Science | Raichur A.M.,University of Johannesburg
Chemical Communications | Year: 2012

Novel composite graphene oxide (GO)/poly(allylamine hydrochloride) (PAH) multilayer capsules have been fabricated by layer-by-layer (LbL) assembly. They were found to possess unique permeability properties compared to traditional LbL capsules. These hybrid capsules showed special "core-shell" loading property for encapsulation of dual drugs simultaneously into the core and shell of the capsules respectively. © 2012 The Royal Society of Chemistry.

Kurapati R.,Indian Institute of Science | Raichur A.M.,Indian Institute of Science | Raichur A.M.,University of Johannesburg
Chemical Communications | Year: 2013

A novel and simple route for near-infrared (NIR)-light controlled release of drugs has been demonstrated using graphene oxide (GO) composite microcapsules based on the unique optical properties of GO. Upon NIR-laser irradiation, the microcapsules were ruptured in a point-wise fashion due to local heating which in turn triggers the light-controlled release of the encapsulated anticancer drug doxorubicin (Dox) from these capsules. © 2013 The Royal Society of Chemistry.

Athalye V.,Cummins | Roy S.S.,Indian Institute of Science | Mahesh T.S.,Indian Institute of Science
Physical Review Letters | Year: 2011

We report experimental implementation of a protocol for testing the Leggett-Garg inequality (LGI) for nuclear spins precessing in an external magnetic field. The implementation involves certain controlled operations, performed in parallel on pairs of spin-1/2 nuclei (target and probe) from molecules of a nuclear magnetic resonance ensemble, which enable evaluation of temporal correlations from an LG string. Our experiment demonstrates violation of the LGI for time intervals between successive measurements, over which the effects of relaxation on the quantum state of target spin are negligible. Further, it is observed that the temporal correlations decay, and the same target spin appears to display macrorealistic behavior consistent with LGI. © 2011 American Physical Society.

Caldeira K.,Carnegie Institution for Science | Bala G.,Indian Institute of Science | Cao L.,Zhejiang University
Annual Review of Earth and Planetary Sciences | Year: 2013

Carbon dioxide emissions from the burning of coal, oil, and gas are increasing atmospheric carbon dioxide concentrations. These increased concentrations cause additional energy to be retained in Earth's climate system, thus increasing Earth's temperature. Various methods have been proposed to prevent this temperature increase either by reflecting to space sunlight that would otherwise warm Earth or by removing carbon dioxide from the atmosphere. Such intentional alteration of planetary-scale processes has been termed geoengineering. The first category of geoengineering method, solar geoengineering (also known as solar radiation management, or SRM), raises novel global-scale governance and environmental issues. Some SRM approaches are thought to be low in cost, so the scale of SRM deployment will likely depend primarily on considerations of risk. The second category of geoengineering method, carbon dioxide removal (CDR), raises issues related primarily to scale, cost, effectiveness, and local environmental consequences. The scale of CDR deployment will likely depend primarily on cost. © Copyright ©2013 by Annual Reviews. All rights reserved.

Govindu V.M.,Indian Institute of Science | Pooja A.,Amazon
IEEE Transactions on Image Processing | Year: 2014

In this paper, we present an extension of the iterative closest point (ICP) algorithm that simultaneously registers multiple 3D scans. While ICP fails to utilize the multiview constraints available, our method exploits the information redundancy in a set of 3D scans by using the averaging of relative motions. This averaging method utilizes the Lie group structure of motions, resulting in a 3D registration method that is both efficient and accurate. In addition, we present two variants of our approach, i.e., a method that solves for multiview 3D registration while obeying causality and a transitive correspondence variant that efficiently solves the correspondence problem across multiple scans. We present experimental results to characterize our method and explain its behavior as well as those of some other multiview registration methods in the literature. We establish the superior accuracy of our method in comparison to these multiview methods with registration results on a set of well-known real datasets of 3D scans. © 2013 IEEE.

Rai M.,Indian Institute of Science | Nongthomba U.,Indian Institute of Science | Grounds M.D.,University of Western Australia
Current Topics in Developmental Biology | Year: 2014

Many aspects of skeletal muscle biology are remarkably similar between mammals and tiny insects, and experimental models of mice and flies (Drosophila) provide powerful tools to understand factors controlling the growth, maintenance, degeneration (atrophy and necrosis), and regeneration of normal and diseased muscles, with potential applications to the human condition. This review compares the limb muscles of mice and the indirect flight muscles of flies, with respect to the mechanisms of adult myofiber formation, homeostasis, atrophy, hypertrophy, and the response to muscle degeneration, with some comment on myogenic precursor cells and common gene regulatory pathways. There is a striking similarity between the species for events related to muscle atrophy and hypertrophy, without contribution of any myoblast fusion. Since the flight muscles of adult flies lack a population of reserve myogenic cells (equivalent to satellite cells), this indicates that such cells are not required for maintenance of normal muscle function. However, since satellite cells are essential in postnatal mammals for myogenesis and regeneration in response to myofiber necrosis, the extent to which such regeneration might be possible in flight muscles of adult flies remains unclear. Common cellular and molecular pathways for both species are outlined related to neuromuscular disorders and to age-related loss of skeletal muscle mass and function (sarcopenia). The commonality of events related to skeletal muscles in these disparate species (with vast differences in size, growth duration, longevity, and muscle activities) emphasizes the combined value and power of these experimental animal models. © 2014 Elsevier Inc.

Bhattacherjee B.,University of Tokyo | Bhattacherjee B.,Indian Institute of Science | Choudhury A.,Harish Chandra Research Institute
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Measurement of the self-coupling of the 125 GeV Higgs boson is one of the most crucial tasks for a high luminosity run of the LHC, and it can only be measured in the di-Higgs final state. In the minimal supersymmetric standard model, heavy CP even Higgs (H) can decay into a lighter 125 GeV Higgs boson (h) and, therefore, can influence the rate of di-Higgs production. We investigate the role of single H production in the context of measuring the self-coupling of h. We have found that the H→hh decay can change the value of Higgs (h) self-coupling substantially, in a low tanβ regime where the mass of the heavy Higgs boson lies between 250 and 600 GeV and, depending on the parameter space, it may be seen as an enhancement of the self-coupling of the 125 GeV Higgs boson. © 2015 American Physical Society.

Sarmah R.,Tezpur University | Ananthakrishna G.,Indian Institute of Science
Acta Materialia | Year: 2015

We investigate the correlation between the band propagation property and the nature and amplitude of serrations in the Portevin-Le Chatelier effect within the framework of the Ananthakrishna model. Several significant results emerge. First, we find that spatial and temporal correlations continuously increase with strain rate from type C to type A bands. Consequently, the nature of the bands also changes continuously from type C to A bands, and so do the changes in the associated serrations. Second, even the smallest extent of propagation induces small amplitude serrations. The spatial extent of band propagation is directly correlated with the duration of small amplitude serrations, a result that is consistent with recent experiments. This correspondence allows one to estimate the spatial extent of band propagation by just measuring the temporal stretch of small amplitude serrations. Therefore, this should be of practical value when only stress versus strain is recorded. Third, the average stress drop magnitude of the small amplitude serrations induced by the propagating bands remains small and nearly constant with strain rate. As a consequence, the fully propagating type A bands are in a state of criticality. We rationalize the increasing levels of spatial and temporal correlations found with increasing strain rates. Lastly, the model also predicts several band morphologies seen in experiments including the Lüders-like propagating band. © 2015 Acta Materialia Inc.

Ramesh N.,Indian Institute of Science | Ramesh N.,University of Sydney | Murtugudde R.,The Interdisciplinary Center
Nature Climate Change | Year: 2013

The El Niño/Southern Oscillation phenomenon, characterized by anomalous sea surface temperatures and winds in the tropical Pacific, affects climate across the globe. El Niños occur every 2-7 years, whereas the El Niño/Southern Oscillation itself varies on decadal timescales in frequency and amplitude, with a different spatial pattern of surface anomalies each time the tropical Pacific undergoes a regime shift. Recent work has shown that Bjerknes feedback (coupling of the atmosphere and the ocean through changes in equatorial winds driven by changes in sea surface temperature owing to suppression of equatorial upwelling in the east Pacific) is not necessary for the development of an El Niño. Thus it is unclear what remains constant through regimes and is crucial for producing the anomalies recognized as El Niño. Here we show that the subsurface process of discharging warm waters always begins in the boreal summer/autumn of the year before the event (up to 18 months before the peak) independent of regimes, identifying the discharge process as fundamental to the El Niño onset. It is therefore imperative that models capture this process accurately to further our theoretical understanding, improve forecasts and predict how the El Niño/Southern Oscillation may respond to climate change. © 2013 Macmillan Publishers Limited. All rights reserved.

Hikal Ltd and Indian Institute of Science | Date: 2010-04-07

The present invention relates to compounds trans (E) and cis (Z) stereoisomers of 4-t-butylgabapentin of formula (11) and (12) and a process for the preparation of the said stereoisomers.

Jatkar D.P.,Harish Chandra Research Institute | Sinha A.,Indian Institute of Science
Physical Review Letters | Year: 2011

We show that the recently proposed Dirac-Born-Infeld extension of new massive gravity emerges naturally as a counterterm in four-dimensional anti-de Sitter space (AdS4). The resulting on-shell Euclidean action is independent of the cutoff at zero temperature. We also find that the same choice of counterterm gives the usual area law for the AdS4 Schwarzschild black hole entropy in a cutoff-independent manner. The parameter values of the resulting counterterm action correspond to a c=0 theory in the context of the duality between AdS3 gravity and two-dimensional conformal field theory. We rewrite this theory in terms of the gauge field that is used to recast 3D gravity as a Chern-Simons theory. © 2011 American Physical Society.

Bhadra K.,Indian Institute of Science | Bhadra K.,Kalyani University | Kumar G.S.,Indian Institute of Science
Biochimica et Biophysica Acta - General Subjects | Year: 2011

Background: Interaction of isoquinoline alkaloids berberine, palmatine, coralyne and sanguinarine with human telomeric quadruplex DNA, dAGGG(TTAGGG)3, has been investigated and compared with ethidium. Methods: Biophysical techniques such as absorption, fluorescence, circular dichroism, optical melting and microcalorimetry have been used. Results: Absorption and fluorescence studies revealed noncooperative 1:1 binding for all the molecules. Coralyne showed highest affinity (106 M-1) and for others it was ~ 105 M-1. The binding affinity varied as coralyne > sanguinarine > berberine > palmatine. Ethidium showed affinity close to sanguinarine. Comparative fluorescence quenching and polarization anisotropy of the emission spectra gave evidence for a stronger stacking interaction of coralyne and sanguinarine compared to berberine and palmatine. Circular dichroic spectral perturbations were similar in all the cases, but a strong induced circular dichroism for the bound molecules was observed only for coralyne and sanguinarine. The interaction of all the alkaloids was exothermic. Binding of coralyne and sanguinarine was predominantly enthalpy driven while that of berberine and palmatine was entropy driven. Heat capacity values of - 169, -198, -105 and - 95 cal/mol K, respectively, for coralyne, sanguinarine, berberine, and palmatine suggested significant differences in the hydrophobic contribution to the binding. Conclusions: This study presents a complete structural and thermodynamic profile of the binding of isoquinoline alkaloids with G-quadruplex. General significance: These results suggest strong and specific binding of these molecules to the G-quadruplex and highlight the differences in their structure in the interaction profile. © 2011 Elsevier B.V. All rights reserved.

Sahoo R.R.,Indian Central Mechanical Engineering Research Institute | Biswas S.K.,Indian Institute of Science
Tribology Letters | Year: 2014

Lithium stearate soap and layered MoS2 nanoparticles encapsulated in lithium stearate soap are prepared in the laboratory, and their lubricating properties are compared with respect to the particle and particle concentration. The tribotracks after friction test was investigated with Raman Spectroscopy, scanning electron microscopy (SEM) and 3D optical profilometry to understand the action mechanism. The status of the soap particles on a tribotrack changes with time, contact pressure and sliding speed. At low pressure and speed, individual solid undeformed soap particle stand proud of the surface and the topography shows marginal difference with sliding time. In these conditions, no frictional difference between the performance of grease with and without the nanoparticles is observed. Increasing the contact pressure and temperature (low speed and high speed) has a dramatic effect as the soap particles melt and the liquid soap flows over the track releasing the hitherto encapsulated nanoparticles. Consequently, the soap smears the track like a liquid, and the nanoparticles now come directly into the interface and are sheared to generate a low-friction tribofilm. At high particle concentration, the sliding time required for melting of the soap and release of MoS2 is reduced, and the tribofilm is more substantial and uniform consisting of smeared MoS2 and carboxylate soap as observed by SEM and 3D optical profilometry. A change in the Raman Spectra is observed with particle concentration, and this is related to morphology and microstructure of the tribofilm generated. © Springer Science+Business Media New York 2013.

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