1,346 research outputs found
Synthesis, Characterization and Irradiation of Fullerene Based Metal Nanocomposites
No full textDocumentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeirosThe present research work entitled “Synthesis, Characterization and Irradiation of Fullerene Based Metal Nanocomposites” envisages the study on the feasibility of using fullerenes, one of the most emerging functional materials as a matrix for the
reinforcement of metal nanoparticles. Fullerene matrix nanoparticles embedded composites are found to exhibit surface plasmon resonance (SPR) by virtue of which a significant enhancement of absorbance of the material become possible; the bifunctional
property of matrix and metal nanoparticles in a single material makes it highly beneficial and applicable for different optical devices, thereby making it poised for emergence as a lucrative energy material.
Understanding that the performance of optical absorbance of nanocomposites is highly influenced by the host microstructure, it has appeared important to monitor the structural conditions of fullerene as matrix material when subjected to such treatments
as considered useful for enhancement of SPR due to noble metal particles in nanocomposites. It is further known that ion beam irradiation is most effective in alteration of SPR behavior of nanoparticles of noble metals like Au and Ag. So the
present study in chapter 4.1 has contemplated to explore the effect of heavy ion beam irradiation (90 MeV Ni ion) on fullerene C60 thin film. As expected the damage of fullerenes has been fluence dependent and that ion tracks of determinable diameter
could be formed by such irradiation.
In view of the fact that elaborate studies on fullerene C70 is till due to be reported in literature, the present research work in chapter 4.2 has investigated and reported the effect of irradiation by different ions viz. 90 MeV Si, 55 MeV Si, 90 MeV Ni and 125
MeV Au on fullerene C70 thin films. Based on the results of the above ion beams of different electronic energy loss (Se), the damage cross section has been calculated for each ion beam, compiled and a relationship between damage cross section and
electronic energy loss is developed which is supposed to be beneficial in estimating the value of damage cross section for any unknown situation of electronic energy loss within the range of present study.
Although the potential of nanoparticles of gold and silver as reinforcement in fullerene C60 and C70 has been amply researched, the potential of copper is yet to receive due research attention in spite of its advantage of interesting mechanical
properties, high electrical conductivity, favorable catalytic properties, appropriate melting point, high stability and high natural abundance in nature. Hence, the present thesis work has reported (chapter 5.1) the results of investigation on the incorporation
of copper nanoparticles in fullerene C60 matrix subjected to irradiation by low energy ion beams (100 keV Ag ion, 350 keV Ar ion). As a corollary of low energy 100 keVAg ion irradiation study the widening of absorption range could be observed due to
hybridization of copper nanoparticles induced SPR and that due to Ag ions getting implanted within in the silicon substrate. The low cost of Cu over Ag and Au makes it more attractive for applications in various fields of optics, electronics, solar energy
conservation, sensors, lubricants and sliding electrical contacts. Effect of high energy (120 MeV Ag) ion irradiation on Cu (18 at. %)-C60 has implicitly demonstrated (chapter 5.2 ) the enhancement of SPR band intensity due to copper nanoparticles; the
concurrent growth of copper nanoparticles at increasing fluences has caused a shift in the position of SPR band.
The chapter 6 of present study has addressed the research questions related to Cu-C70 nanocomposite thin films under ion irradiation of various energies. The low energy ion beam irradiation (350 keV Ar ion) of Cu (10 at.%)-C70 nanocomposite thin films
have been able to exhibit SPR band due to copper only after irradiation at fluence of 1×1015 ions/cm2. The SPR band increases its intensity with increasing fluence and got shifted towards lower wavelength side. This is in contrast with the pristine which has
not exhibited any SPR due to copper presumably due to its low concentration. The similar behavior was also exhibited by this composite subjected to high energy ion beam irradiation (120 MeV Ag ion) with the exception that SPR could be obtained
only at a higher fluence like 3×1013 ions/cm2. Since any fluence higher than 3×1013 ions/cm2 has not been employed in the present study it is not possible to be conclusive if it would also exhibit a blue shift with still increasing fluence, which, it seems would occur most likely. However, the studies in chapter 6 clearly authenticates that both the concentration of embedded nanoparticles and the change in optical properties of irradiated fullerenes are responsible for determining the intensity and the position of SPR due to copper in fullerene C70 matrix
Arbitration and Dispute Settlement in Foreign Indirect Investment. The increasing significance and use of arbitration in international loan agreements, syndicated loans and international bond issues
No full textThis dissertation examines the suitability of arbitration for the resolution of securities regulatory claims and it adoption globally, which has resulted in international arbitration becoming the favoured dispute resolution mechanism in the securities industry. The author explains that disputes arising out of international bilateral and syndicated loan agreements are generally considered to be arbitrable, while international bond disputes are often derived from the controversies over the application of mandatory national laws and the compliance with securities regulation provisions - so the arbitrability of international bond disputes depends on the acceptance of the arbitrability of securities regulatory claims
A monolithically integrated power JFET and Junction Barrier Schottky diode in 4H silicon carbide
No full textEfficiency of power management circuits depends significantly on their constituent switches and rectifiers. The demands of technology are increasingly running up against the intrinsic properties of Si based power devices. 4H-Silicon Carbide (SiC) has superior properties that make it attractive for high power applications. SiC rectifiers are already a competitive choice and SiC switches have also been commercialized recently. Junction Barrier Schottky (JBS) diodes, which combine the advantages of PN and Schottky, have higher Figure of Merit (FOM) as rectifiers. Among switches, a robust and mature process has been developed for Silicon Carbide Vertical Junction Field Effect Transistors (VJFETs), which currently gives it the highest unipolar FOM. Switches are frequently combined with anti-parallel diodes in power circuits. This thesis describes the development of a SiC-based monolithically integrated power switch and diode. Monolithic integration increases reliability and efficiency, and reduces cost. Because of their superior properties and similarities in fabrication, we chose the SiC VJFET and JBS diode as the switch and rectifier. Detailed design, fabrication and characterization of the integrated switch to block above 800 V and conduct current beyond 100 A/cm2 is explained. In this process, the first physics-based 2-D compact model is developed for reverse leakage in a JBS diode as a function of design parameters. Since the gate-channel junctions of SiC VJFETs cannot be assumed to be abrupt, an existing analytical model for Si VJFETs is extended to account for graded gate-channel junctions. Using these analytical models, design rules are developed for the VJFET and JBS diode. Finite element simulations are used to find the best anode layout of the JBS diode and optimize electric field termination in the integrated device to ensure their capability to operate at high voltage. Finally, a spin-on glass based process is developed for filling the gate trenches of the VJFET to improve long-term robustness in extreme environments. The integrated power switch developed in this thesis points to the attractions of monolithic integration in SiC power circuits. Analytical compact design equations derived here will facilitate faster and easier design of switches and rectifiers for desired circuit operation.Ph. D.Includes bibliographical referencesIncludes vitaby Rahul Radhakrishna
Microbial Symphony: Navigating the Intricacies of the Human Oral Microbiome and Its Impact on Health
No full textThis comprehensive review delves into the forefront of research on the human oral microbiome, exploring recent advancements that span microbial colonization, state-of-the-art detection methodologies, and the complex interplay involved in disease progression. Through an exhaustive analysis of the contemporary literature, we illuminate the dynamic orchestration of microbial communities within the oral cavity, underscoring their pivotal role in health and disease. Cutting-edge detection techniques, including metagenomics and high-throughput sequencing, are discussed regarding their transformative impact on understanding the intricacies of oral microbial ecosystems. As we stand on the cusp of a new decade, this review anticipates a paradigm shift in the field, emphasizing the potential for rapid identification and targeted management of detrimental oral microorganisms. Insights gained from this exploration not only contribute to our fundamental understanding of the oral microbiome but also hold promise for the development of innovative therapeutic strategies to maintain oral health. This article aims to serve as a valuable resource for researchers, clinicians, and public health professionals engaged in unraveling the mysteries of the microbial symphony within the human oral cavity
Primary Pulmonary Synovial Sarcoma: Is it Worth All the Hard Work?
No full textSynovial sarcoma (SS) is highly malignant tumor that occurs mainly in adolescents and young adults and is usually seen in the extremities. However, primary SS arising from the lung is extremely rare, accounting for 0.3% to 1.3%. Primary pulmonary SS (PPSS) is an extremely aggressive malignant tumor that can invade adjacent organs or give distant metastases. Besides clinical evaluation and imaging methods for definitive diagnosis, immunohistochemical examination is must. We report a case of elderly male with left lung mass lesion invading into the pericardium and left-sided pleural effusion with a history of smoking. Positron emission tomography (PET)–computerised tomography (CT)-guided trucut biopsy from lung mass lesion led to the diagnosis, and thoracoscopic pleural biopsy showed the pleural involvement with final diagnosis of PPSS (monophasic type). There are no guidelines for optimal treatment due to the rarity of such tumors. Current treatment includes resectional surgery and adjuvant chemotherapy and/or radiotherapy. But because of advanced age and poor performance status, our patient was not candidate for any treatment but palliation
Logic Realization Using Regular Structures in Quantum-Dot Cellular Automata (QCA)
No full textSemiconductor industry seems to approach a wall where physical geometry and power density issues could possibly render the device fabrication infeasible. Quantum-dot Cellular Automata (QCA) is a new nanotechnology that claims to offer the potential of manufacturing even denser integrated circuits, which can operate at high frequencies and low power consumption. In QCA technology, the signal propagation occurs as a result of electrostatic interaction among the electrons as opposed to flow to the electrons in a wire. The basic building block of QCA technology is a QCA cell which encodes binary information with the relative position of electrons in it. A QCA cell can be used either as a wire or as logic. In QCA, the directionality of the signal flow is controlled by phase-shifted electric field generated on a separate layer than QCA cell layer. This process is called clocking of QCA circuits. The logic realization using regular structures such as PLAs have played a significant role in the semiconductor field due to their manufacturability, behavioral predictability and the ease of logic mapping. Along with these benefits, regular structures in QCA\u27s would allow for uniform QCA clocking structure. The clocking structure is important because the pioneers of QCA technology propose it to be fabricated in CMOS technology. This thesis presents a detailed design implementation and a comparative analysis of logic realization using regular structures, namely Shannon-Lattices and PLAs for QCAs. A software tool was developed as a part of this research, which automatically generates complete QCA-Shannon-Lattice and QCA-PLA layouts for single-output Boolean functions based on an input macro-cell library. The equations for latency and throughput for the new QCA-PLA and QCA-Shannon-Lattice design implementations were also formulated. The correctness of the equations was verified by performing simulations of the tool-generate layouts with QCADesigner. A brief design trade-off analysis between the tool-generated regular structure implementation and the unstructured custom layout in QCA is presented for the full-adder circuit
TOWARDS AUTOMATIC GENERATION OF QUESTIONS ACROSS FORMAL DOMAINS
No full textPh.DDOCTOR OF PHILOSOPHY (SOC
Recommender Systems: An Algorithm To Predict Who Rate What
No full textRecommender systems are systems that recommend content for us by looking at certain factors including what other people are doing as well as what we are doing. Examples of such systems present today are Amazon.com recommending books, CDs, and other products; Netflix recommending movies etc. These systems basically recommend items or movies to customers based on the interests of the present customer and other similar customers who purchased or liked the same item or movie. Our paper goes beyond the concept of overall generic ranking and provides personalized recommendation to users. Despite all the advancements, recommender systems still face problems regarding sparseness of the known ratings within the input matrix. The ratings are given in the range of (1-5) and present systems predict ``What are the ratings\u27\u27 but here we propose a new algorithm to predict ``Who rate what\u27\u27 by finding contrast points in user-item input matrix. Contrast points are the points which are farthest from the known rated items and most unlikely to be rated in future. We experimentally validate that our algorithm is better than traditional Singular Value Decomposition (SVD) method in terms of effectiveness measured through precision/recall
Chiral superconductivity from repulsive interactions in doped graphene
No full textAuthor Manuscript 17 Sep 2011Chiral superconductivity, which breaks time-reversal symmetry, can exhibit a wealth of fascinating properties that are highly sought after for nanoscience applications. We identify doped graphene monolayer as a system where chiral superconductivity can be realized. In this material, a unique situation arises at a doping where the Fermi surface is nested and the density of states is singular. In this regime, d-wave superconductivity can emerge from repulsive electron–electron interactions. Using a renormalization group method, we argue that superconductivity dominates over all competing orders for generic weak repulsive interactions. Superconductivity develops simultaneously in two degenerate d-wave pairing channels. We argue that the resulting superconducting state is of chiral type, with the phase of the superconducting order parameter winding by 4π around the Fermi surface. Realization of this state in doped graphene will prove that superconductivity can emerge from electron–electron repulsion, and will open the door to applications of chiral superconductivity
Adding diversity and realism to LAVA, a vulnerability addition system
No full textThesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 63-64).In this thesis, I designed and implemented several modifications to LAVA, a vulnerability addition system, with the goal of improving realism and diversity of the injected bugs. Specifically, I describe three separate improvements: a method to add fake bugs alongside real ones in order to decrease bug discoverability, two approaches to increase the complexity of the data flow of the inserted bugs, and a standalone program that uses equality saturation to diversify C-source codebases that can be added as a final stage to LAVA. Finally, I present two instances of bug-finding competitions-AutoCTF and Rode0day-that I helped design and run, which leveraged LAVA and the augmentations described in this thesis in order to accomplish their respective goals.by Rahul Sridhar.M. Eng
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