69 research outputs found

    Dynamic Voltage and Frequency Scaling for Wireless Network-on-Chip

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    Previously, research and design of Network-on-Chip (NoC) paradigms where mainly focused on improving the performance of the interconnection networks. With emerging wide range of low-power applications and energy constrained high-performance applications, it is highly desirable to have NoCs that are highly energy efficient without incurring performance penalty. In the design of high-performance massive multi-core chips, power and heat have become dominant constrains. Increased power consumption can raise chip temperature, which in turn can decrease chip reliability and performance and increase cooling costs. It was proven that Small-world Wireless Network-on-Chip (SWNoC) architecture which replaces multi-hop wire-line path in a NoC by high-bandwidth single hop long range wireless links, reduces the overall energy dissipation when compared to wire-line mesh-based NoC architecture. However, the overall energy dissipation of the wireless NoC is still dominated by wire-line links and switches (buffers). Dynamic Voltage Scaling is an efficient technique for significant power savings in microprocessors. It has been proposed and deployed in modern microprocessors by exploiting the variance in processor utilization. On a Network-on-Chip paradigm, it is more likely that the wire-line links and buffers are not always fully utilized even for different applications. Hence, by exploiting these characteristics of the links and buffers over different traffic, DVFS technique can be incorporated on these switches and wire-line links for huge power savings. In this thesis, a history based DVFS mechanism is proposed. This mechanism uses the past utilization of the wire-line links & buffers to predict the future traffic and accordingly tune the voltage and frequency for the links and buffers dynamically for each time window. This mechanism dynamically minimizes the power consumption while substantially maintaining a high performance over the system. Performance analysis on these DVFS enabled Wireless NoC shows that, the overall energy dissipation is improved by around 40% when compared Small-world Wireless NoCs

    Poly(Ethylene Oxide) Based Bottle-Brush Polymers and their Interaction with the Anionic Surfactant Sodium Dodecyl Sulphate : Solution and Interfacial Properties

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    The aim of this thesis work is to study the physico-chemical properties of poly(ethylene oxide), PEO, based brush polymers both in solution and at solid/aqueous interfaces. The importance of studying the surface properties of brush polymers can be related to a broad spectrum of interfacial-related applications such as colloidal stability, lubrication, detergency, protein repellency to name a few. In many applications it is desirable to form brush-like structures through simple physisorption. In this context the surface properties of PEO based brush polymers differing in molecular architecture were studied, using ellipsometry and surface force apparatus (SFA), to gain some understanding regarding the effect of molecular architecture on the formation of brush structures. The molecular architecture was varied by varying the charge/PEO ratio along the backbone. This study demonstrates that the formation of a brush structure at solid/aqueous interface is due to interplay between the attraction of the backbone to the surface and the repulsions between the PEO side chains. An optimal balance between the two antagonistic factors is required if one aims to build a well-defined brush structure at the interface. In this study the brush-like structures are formed when 25-50% of the backbone segments carry poly(ethylene oxide) side chains. Scattering techniques such as light and neutron reveal that these brush polymers are stiff-rods up to a charge to PEO ratio of 75:25. These stiff PEO brush polymer easily replace the more flexible linear PEO at the silica/water interface, the reason being that the entropy loss on adsorption is smaller for the brush polymer due to its stiff nature.  Polymer-surfactant systems play a ubiquitous role in many technical formulations. It is well known that linear PEO, which adopts random coil conformation in aqueous solution, interact strongly with the anionic surfactant, Sodium Dodecyl Sulphate (SDS). It is of interest to study the interaction between SDS and brush PEO owing to the fact that the PEO side chains have limited flexibility as compared to the linear PEO.  The interaction between brush PEO and the anionic surfactant SDS in solution are studied using different techniques such as NMR, tensiometry, SANS and light scattering. The main finding of this study is that the interaction is weaker compared to the linear PEO-SDS interactions which poses an interesting question regarding the role of chain flexibility in polymer-surfactant interactions.QC 2010081

    Possibility of HIV-1 Protease Inhibitors-Clinical Trial Drugs as Repurposed Drugs for SARSCoV-2 Main Protease: A Molecular Docking, Molecular Dynamics and Binding Free Energy Simulation Study

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    Initially, the SARS-CoV-2 virus was emerged from Wuhan, China and rapidly spreading across the world and urges the scientific community to develop antiviral therapeutic agents. Among several strategies, drug repurposing will help to react immediately to overcome COVID-19 pandemic. In the present study, we have chosen two clinical trial drugs TMB607 and TMC310911 are the inhibitors of HIV-1 protease to use as the inhibitors of SARS-CoV-2 main protease (Mpro) enzyme. To make use of these two inhibitors as the repurposed drugs for COVID-19, it is essential to know the molecular basis of binding mechanism of these two molecules with the SARS-CoV-2 main protease (Mpro). Understand the binding mechanism; we performed the molecular docking, molecular dynamics (MD) simulations and binding free energy calculations against the SARS-CoV-2 Mpro. The docking results indicate that both molecules form intermolecular interactions with the active site amino acids of Mpro enzyme. However, during the MD simulations, TMB607 forms strong interactions with the key amino acids of Mpro and remains intact. The RMSD and RMSF values of both complexes were stable throughout the MD simulations. The MM-GBSA binding free energy values of both complexes are -43.7 and -34.9 kcal/mol, respectively. This in silico study proves that the TMB607 molecule binds strongly with the SARS-CoV-2 Mpro enzyme and it is suitable for the drug repurposing of COVID-19 and further drug designing.</p

    Topology of electron density and electrostatic potential of HIV reverse transcriptase inhibitor zidovudine from high resolution X-ray diffraction and charge density analysis

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    Azidothymidine (AZT) is a first anti-HIV drug namely Zidovudine used for HIV treatment, which binds to the viral DNA primer and inhibits the HIV reverse transcription. The side effects of this powerful drug are severe and the detailed understanding of its electronic structure helps to design new drugs from the AZT molecule. Present study aims to determine the structure of AZT at electronic level from the experimental charge density analysis as well as the solid state DFT calculations. AZT was crystallized and low temperature high resolution X-ray diffraction intensity data has been measured up to sin (theta/lambda)(max) = 1.1 angstrom(-1) at 100.0 (2) K. The crystal structure of AZT was determined, which reveals the information that the AZT compound crystallizes with two molecules in the asymmetric unit which are conformationally different and linked through strong hydrogen bonding interactions (dimer). The Hirshfeld surface of both molecules shows the locations of weak and strong interactions. Further, a multipole model refinement was carried out using Hansen-Coppens multipole formalism. The experimental topological properties of electron density of AZT molecules were determined and compared with the results of theoretical DFT calculations based on solid state and gas phase studies. The charge density distribution of the two molecules in the asymmetric unit is unequal and shows some difference. The topological properties of O-H center dot center dot center dot O, O-H center dot center dot center dot N, C-H center dot center dot center dot N, H center dot center dot center dot H and azide center dot center dot center dot azide group interactions are also determined. The electrostatic potential (ESP) surface of both AZT molecules in the crystal exhibits high electronegative regions around the O, N atoms and also around the azide group, however, ESP regions of molecules (I) and (II) are not similar. (C) 2018 Elsevier B.V. All rights reserved
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