311 research outputs found
Fading correlation of co-located transmitters
No full textFading or attenuation of a signal due to environment is a phenomenon often encountered in wireless communications. It is expected that co-located transmitters i.e. transmitters placed very close to each other show a high signal fading correlation due to the presence of similar fading environment. In this thesis, we present an experimental study of this phenomenon. Correlation of received signal strengths obtained from co-located transmitters in dynamically varying environments indicate that the large scale signal variations (shadow fading) are highly correlated while the small scale variations (multipath or fast fading) show a low correlation. Highly correlated large scale variations suggest a presence of same large shadowing elements in the transmit-receive path while a low correlation among the multipath variations is due to mutual coupling between the antennas at very close distances. This has two implications: it suggests that shadow fading variations can serve as an indicator of the co-location of closely spaced transmitters while the multipath variations cannot. However, low multipath signal correlations suggest that antenna diversity could be investigated for implementation in mobile handsets.M.S.Includes bibliographical referencesby Prashant Jadha
Fabrication of nanoadjuvant with poly-ɛ-caprolactone (PCL) for developing a single-shot vaccine providing prolonged immunity [Corrigendum]
No full textPrashant CK, Bhat M, Srivastava SK, et al. Int J Nanomedicine. 2014;9:937–950.On page 937, the author affiliations have been listed incorrectly. The correct author list is as follows:Chandravilas Keshvan Prashant1Madhusudan Bhat2Sandeep Kumar Srivastava2Ankit Saxena3Manoj Kumar4Amar Singh3Mohammed Samim5Farhan Jalees Ahmad6Amit Kumar Dinda21Faculty of Engineering and Interdisciplinary Sciences, Jamia Hamdard, New Delhi, India; 2Department of Pathology, 3Department of Transplant Immunology and Immunogenetics, All India Institute of Medical Sciences, New Delhi, India; 4Centre for Biomedical Engineering, Indian Institute of Technology, New Delhi, India; 5Department of Chemistry, Faculty of Science, Jamia Hamdard, New Delhi, India; 6Department of Pharmaceutics, Faculty of Pharmacy, Jamia Hamdard, New Delhi, IndiaRead the original articl
Computational electronic structure studies of novel condensed matter phases
Full text linkThis dissertation compiles the bulk of my work as a PhD student in the research group of Professor Prashant K. Jain at University of Illinois at Urbana-Champaign. My research was exclusively in the field of theoretical chemistry and materials science: I employed high-performance computing tools to perform electronic structure investigations of novel crystalline materials synthesized, some for the very first time, in the group. My placement in the experimentally-focused Jain group afforded multiple opportunities in which the discoveries of my fellow group members prompted me to conduct stand-alone or collaborative theoretical investigations of new nanomaterials. A summary of the experimental backdrop to my work is presented in Chapter 1, along with a description of the theoretical methods that were the mainstay of my PhD research. Chapter 2 presents work in which my density functional theory (DFT) calculations improved our understanding of the metastability of a previously unobserved vacancy ordering in a Cu2Se. Chapter 3 presents a different direction of investigations that we conducted on Cu2Se, this time into its superionic properties. The nucleation, kinetics, and correlation of lattice strain to the order-disorder superionic phase transition were explored through a combination of transmission electron microscopy and DFT. The correlation between lattice strain and superionicity is expanded upon in Chapter 4 where Prashant and I developed a theoretical basis on which to understand compressively strain-stabilized superionicity in Cu2Se and Li2Se. Chapter 5 shifts away from Cu2Se on to HgSe. Additionally, the focus changes from the structure and transport of cations to the structure and transport of electrons, specifically the electron-conducting surface states found in topological phases of matter. Bulk band-structure calculations and charge density character analysis that I carried out led us to hypothesize that a hexagonal phase of HgSe newly-synthesized bny the Jain group was a 3-D topological insulator. The unique topological surface states (TSS) of HgSe and their dependence on strain, crystallographic symmetry, and surface faceting are determined by DFT and presented in Chapter 6. Particularly, the effect of lattice strain on the dispersion and spin texture circles back to the central theme in the studies of super-ionic crystals: that small amounts of strain can significantly alter the charge transport properties of a material.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-05-01The student, Daniel Dumett Torres, accepted the attached license on 2020-04-21 at 14:56.The student, Daniel Dumett Torres, submitted this Dissertation for approval on 2020-04-21 at 15:04.This Dissertation was approved for publication on 2020-04-24 at 13:06.DSpace SAF Submission Ingestion Package generated from Vireo submission #15022 on 2020-08-25 at 17:40:29Made available in DSpace on 2020-08-27T00:49:58Z (GMT). No. of bitstreams: 2
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Zalmoxis muelleri
No full textZalmoxis muelleri new name Zalmoxis neoguinensis Müller, 1917, p. 253, 256–258, figs. 3–5 [junior secondary homonym of Euzalmoxis neoguinensis Roewer, 1915]; Roewer, 1923, p. 90, fig. 87 a–b.; Goodnight & Goodnight, 1957, p. 81–83. Gagirius neoguinensis [partim.]: Roewer, 1949 a, p. 28. Record. *Sattelberg, Wilhelmshafen, New Guinea [Madang, Papua New Guinea]; other unspecified localities in New Guinea. Etymology. Our replacement name honors the original author of this species, Adolf Müller.Published as part of Sharma, Prashant P., Kury, Adriano B. & Giribet, Gonzalo, 2011, Zalmoxidae (Arachnida: Opiliones: Laniatores) of the Paleotropics: a catalogue of Southeast Asian and Indo-Pacific species, pp. 37-58 in Zootaxa 2972 on pages 49-50, DOI: 10.5281/zenodo.20662
Designing order–disorder transformation in high-entropy ferritic steels.
Full text linkOrder–disorder transformations hold an essential place in chemically complex high-entropy ferritic steels (HEFSs) due to their critical technological application. The chemical inhomogeneity arising from mixing of multi-principal elements of varying chemistry can drive property altering changes at the atomic scale, in particular short-range order. Using density-functional theory-based linear-response theory, we predict the effect of compositional tuning on the order–disorder transformation in ferritic steels—focusing on Cr–Ni–Al–Ti–Fe HEFSs. We show that Ti content in Cr–Ni–Al–Ti–Fe solid solutions can be tuned to modify short-range order that changes the order–disorder path from BCC-B2 (Ti atomic-fraction = 0) to BCC-B2-L21 (Ti atomic-fraction > 0) consistent with existing experiments. Our study suggests that tuning degree of SRO through compositional variation can be used as an effective means to optimize phase selection in technologically useful alloys.This article is published as Singh, Prashant, and Duane D. Johnson. "Designing order–disorder transformation in high-entropy ferritic steels." Journal of Materials Research 27 (2022): 136-144. DOI: 10.1557/s43578-021-00336-w. Copyright 2021 The Author(s). Attribution 4.0 International (CC BY 4.0). DOE Contract Number(s): AC02-07CH11358. Posted with permission
Development and Formulation of Novel Antimicrobial Peptides (AMPs) for Activity Against Staphylococcus Aureus
Full text linkThe first part of the project involves the development of new antimicrobial peptide (antibiotics). This will initially involve generating a peptide array by surveying the literature and using software programs such as quantitative structure-activity relationship (QSAR). The effectiveness of the peptide array against Staphylococcus aureus was tested at the Langara microbiology labs. The peptides (2-3 peptides) with the best activity will be further studied
Spatiotemporal characteristics of high-density gas jet and absolute determination of size and density of gas clusters
No full text© 2020, The Author(s).Properties of gas clusters such as the size and number density when expanding into the vacuum after passing through a conical nozzle are analyzed for argon at an average density of 1020/cm3. Temporally and spatially resolved size and density distribution were measured from all-optical methods of Rayleigh scattering measurement and Nomarski interferometry using a CW laser. At the gas backing pressure of 80 bar, Ar clusters as large as 100 nm were obtained, which differs significantly from the size estimated by the conventional Hagena scaling law. The two independent methods of cluster characterization presented here would be useful to precisely determine the initial conditions in a variety of intense laser-cluster interaction driven applications such as neutron generation, thermonuclear fusion, efficient x-ray emission, and energetic ion acceleration.11sci
Density-functional theory of material design: fundamentals and applications-I
No full textThis article is part-I of a review of density-functional theory (DFT) that is the most widely used method for calculating electronic structure of materials. The accuracy and ease of numerical implementation of DFT methods has resulted in its extensive use for materials design and discovery and has thus ushered in the new field of computational material science. In this article, we start with an introduction to Schrödinger equation and methods of its solutions. After presenting exact results for some well-known systems, difficulties encountered in solving the equation for interacting electrons are described. How these difficulties are handled using the variational principle for the energy to obtain approximate solutions of the Schrödinger equation is discussed. The resulting Hartree and Hartree–Fock theories are presented along with results they give for atomic and solid-state systems. We then describe Thomas–Fermi theory and its extensions which were the initial attempts to formulate many-electron problem in terms of electronic density of a system. Having described these theories, we introduce modern DFT by discussing Hohenberg–Kohn theorems that form its foundations. We then go on to discuss Kohn–Sham (KS) formulation of DFT in its exact form. Next, local density approximation (LDA) is introduced and solutions of KS equation for some representative systems, obtained using the LDA, are presented. We end part-I of the review describing the contents of part-II.This article is published as Singh, Prashant, and Manoj K. Harbola. "Density-functional theory of material design: fundamentals and applications-I." Oxford Open Materials Science 1, no. 1 (2021): itab018.
DOI: 10.1093/oxfmat/itab018.
Copyright 2021 The Author(s).
Attribution 4.0 International (CC BY 4.0).
DOE Contract Number(s): AC02-07CH11358.
Posted with permission
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