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Your search keyword '"Nayak, Alpana"' showing total 102 results
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102 results on '"Nayak, Alpana"'

1. Microwave synthesis of molybdenene from MoS2

Author

Sahu, Tumesh Kumar, Kumar, Nishant, Chahal, Sumit, Jana, Rajkumar, Paul, Sumana, Mukherjee, Moumita, Tavabi, Amir H., Datta, Ayan, Dunin-Borkowski, Rafal E., Valov, Ilia, Nayak, Alpana, and Kumar, Prashant

Published
2023
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18. Atomic Switches

Author

Terabe, Kazuya, primary, Tsuruoka, Tohru, additional, Hasegawa, Tsuyoshi, additional, Nayak, Alpana, additional, Ohno, Takeo, additional, Nakayama, Tomonobu, additional, and Aono, Masakazu, additional

Published
2016
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24. Films of novel mesogenic molecules at air-water and air-solid interfaces

Author

Nayak, Alpana, Suresh, K.A., Pal, Santanu Kumar, and Kumar, Sandeep

Subjects
Thin films, Multilayered -- Research, Thin films, Multilayered -- Properties, Surface chemistry, Chemicals, plastics and rubber industries
Abstract

The studies of two novel ionic discotic mesogenic molecules exhibiting stable Langmuir monolayer which show negligible hysteresis on expanding and compressing is demonstrated.

Published
2007

28. Temperature-Induced Nanoarchitectonics of Monolayer Self-Assembly of Heterocoronene-Based Discotic Liquid Crystals

Author

Kumar, Nishant, Sahu, Subhasish, Paul, Himangshu, Rout, Mukesh Kumar, De, Joydip, Pal, Santanu Kumar, Mishra, Puneet, and Nayak, Alpana

Abstract

Enhancing molecular self-assembly at the monolayer level offers significant potential for various applications. For monolayers made of π-conjugated discotic liquid crystal (DLC) molecule nanowires, achieving precise separation and alignment of these nanowires has been a long-standing challenge. This research explores an approach using the manipulation of subphase temperature and surface pressure within a Langmuir trough to control molecular nanowire separation. We observe notable temperature-dependent behavior: as the temperature increases from 5 to 30 °C, the monolayer collapse pressure rises steadily. In contrast, temperatures from 35 to 50 °C exhibit an initial small plateau with a nonzero slope that becomes more distinct with rising temperature. Our study of Langmuir–Blodgett (LB) films provides crucial insights into the monolayer’s structure. At lower temperatures, the LB films show coalesced molecular nanowires, whereas at higher temperatures, the DLC nanowires separate and form an interconnected network. Remarkably, upon compression, this network transforms into a compact, highly uniform monolayer. To explain these temperature-dependent behaviors, we examine the area relaxation curves, which indicate a two-step molecular loss mechanism involving desorption and monolayer collapse due to the nucleation and growth of critical nuclei. This extensive study offers valuable insights into the dynamic interaction of the temperature, surface pressure, and molecular assembly, enhancing our understanding of the fundamental processes in monolayer self-assembly.

Published
2024
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32. Discogen-DNA complex films at air-water and air-solid interfaces

Author

Nayak, Alpana and Suresh, K.A.

Subjects
DNA -- Chemical properties, Nanotechnology -- Research, Pyridinium compounds -- Structure, Pyridinium compounds -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

A nanoindentation technique was used to study qualitatively the hardness of pure pyridinium salt tethered with hexaalkoxytriphenylene (PyTp) and PyTp-DNA complex films at the nanometer scale. The results showed that the PyTp-DNA complex films are two times harder than the pure PyTp films.

Published
2008

35. Triptycene‐based fluorescent polymers with pendant alkyl chains: interaction with fullerenes and morphology of thin films.

Author

Ansari, Mosim, Mallik, Samapika, Mondal, Snehasish, Bera, Ranajit, Jana, Achintya, Nayak, Alpana, and Das, Neeladri

Subjects
TRIPTYCENES, FLUORESCENT polymers, SUBSTITUENTS (Chemistry), FULLERENES, THIN films, MONOMERS
Abstract

We report unique triptycene‐based alternating copolymers bearing long alkyl chains as pendants. Syntheses utilized 2,6‐diethynyltriptycene and appropriate alkyloxyarene monomers polymerized via Sonogashira cross‐coupling reaction to yield triptycene‐based poly(phenylene ethynylene)s. Resulting polymers are soluble in organic solvents and were characterized using various techniques. Experimental results suggest the polymers are thermally stable and fluorescent. The fluorescence emission is quenched in the presence of fullerenes (C60 and C70) suggesting strong host–guest interactions. The magnitude of the binding constant between the polymers and these fullerenes was determined to be of the order of 105 mol L−1. The effects of chain length on the morphology and wettability of the polymers on silicon substrates were studied using atomic force microscopy. Three distinct dewetting patterns, i.e. spherical domains, fractal structures and ring structures, were observed with variation in the pendant chain length. This ability to control the thin‐film morphology of the polymers may have potential technological applications, which include but are not limited to sensors, fluorescent coatings and organic electronics. © 2018 Society of Chemical Industry Triptycene‐based organosoluble fluorescent polymers with pendant alkyl chains (TPPEs) were synthesized that interact strongly with fullerenes. The morphology of self‐assembled TPPEs on silicon substrate is dependent on pendant chain length. [ABSTRACT FROM AUTHOR]

Published
2019
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37. Evaluation of silicon- and carbon-face SiO2/SiC MOS interface quality based on scanning nonlinear dielectric microscopy.

Author

Norimichi Chinone, Nayak, Alpana, Ryoji Kosugi, Yasunori Tanaka, Shinsuke Harada, Hajime Okumura, and Yasuo Cho

Subjects
*SILICON oxide, *SILICON carbide, *SCANNING probe microscopy, *STANDARD deviations, *DIELECTRICS
Abstract

A strong positive correlation was found between the trap density (Dit) at the SiO2/SiC interface and signal variation in a scanning nonlinear dielectric microscopy (SNDM) image. Si-face and C-face SiC wafers with a 45-nm-thick oxide layer were examined by the conventional high-low method and SNDM, which is a type of scanning probe microscopy. The Dit value measured by the highlow method and the standard deviation of normalized SNDM images exhibited a strong positive correlation, which means that the standard deviation of the normalized SNDM image can be used as a universal measure of the SiO2/SiC interface quality. Using this measure, a quick evaluation of Dit using SNDM is possible. [ABSTRACT FROM AUTHOR]

Published
2017
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40. Universal Parameter Evaluating SiO2/SiC Interface Quality Based on Scanning Nonlinear Dielectric Microscopy

Author

Chinone, Norimichi, Nayak, Alpana, Kosugi, Ryoji, Tanaka, Yasunori, Harada, Shinsuke, Kiuchi, Yuji, Okumura, Hajime, and Cho, Yasuo

Abstract

Oxidized both silicon-face (Si-face) and carbon-face (C-face) wafers with various post-oxidation-annealing conditions were measured by scanning nonlinear dielectric microscopy (SNDM) and method for evaluating SiO2/SiC interface quality using SNDM was investigated. We found that the normalized standard deviation of SNDM image was good parameter to evaluate SiO2/SiC interface of Si and C-face. SNDM measurement does not need electrode fabrication to measure C-V curve, but needs just scan on the oxidized wafer with conductive tip, which is easier and quicker. This technique enables us to quickly examine the effect of variation of process parameters in MOS fabrication and to effectively reduce the time needed for R&D cycle.

Published
2017
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