Search

Your search keyword '"Ray, Ruma"' showing total 674 results
Start Over Author "Ray, Ruma"
674 results on '"Ray, Ruma"'

7. Evaluation of Porosity for Gamma Irradiated Poly(ethylene oxide): A New Approach Using Microscopic Image Aided with Computer Programming

Author

Patla, Subir K., Mukhopadhyay, Madhumita, Giri, Abhra, Ray, Ruma, and Tarafdar, Sujata

Subjects
Physics - Applied Physics, Condensed Matter - Soft Condensed Matter
Abstract

Porous polymer films of Poly(ethylene oxide)(PEO) are synthesized by solution casting technique using gamma irradiated: (a) PEO powder (S-series) and (b) PEO - methanol solution (L-series). Pore phase forms instantaneously during preparation. Optimization of the pore content and distribution enables tailoring of associated properties for multifaceted applications. This method could be analyzed for mapping of porosity and average pore size. Practicability and repeatability of the developed programme has been established for monophasic system using backscattered imaging mode of SEM. This program is underdevelopment, but PROGIMAGE-POR bears the novelty of using image from either 2D-or 3D imaging system and could be applied for intricate composite/layered system., Comment: 15 figures

Published
2018

13. A New Approach of Using Microscopic Image Aided Computer Programming for Evaluation of Porosity and Aerosity: Case Studies Using Polymeric Films and Functional Matrices

Author

Giri, Abhra, Patla, Subir K., Mukhopadhyay, Madhumita, Mukhopadhyay, Jayanta, Mukherjee, Monalisa, Ray, Ruma, Tarafdar, Sujata, Lovell, Nigel H., Advisory Editor, Oneto, Luca, Advisory Editor, Piotto, Stefano, Advisory Editor, Rossi, Federico, Advisory Editor, Samsonovich, Alexei V., Advisory Editor, Babiloni, Fabio, Advisory Editor, Liwo, Adam, Advisory Editor, Magjarevic, Ratko, Advisory Editor, Mukherjee, Moumita, editor, Mandal, J.K., editor, Bhattacharyya, Siddhartha, editor, Huck, Christian, editor, and Biswas, Satarupa, editor

Published
2021
Full Text
View/download PDF

15. Concomitant Transthyretin Amyloidosis and Severe Aortic Stenosis in Elderly Indian Population: A Pilot Study

Author

Singal, Aayush Kumar, Bansal, Raghav, Singh, Avinainder, Dorbala, Sharmila, Sharma, Gautam, Gupta, Kartik, Saxena, Anita, Bhargava, Balram, Karthikeyan, Ganesan, Ramakrishnan, Sivasubramanian, Bisoi, Akshay Kumar, Hote, Milind Padmakar, Rajashekar, Palleti, Chowdhury, Ujjwal Kumar, Devagourou, Velayoudam, Patel, Chetan, Ray, Ruma, Arawa, Sudheer Kumar, and Mishra, Sundeep

Published
2021
Full Text
View/download PDF

20. Structural Modificationand Variation in the Kinetics of Isoconversional Phenomena: A Study on the Effect of Gamma Irradiation on Poly (Ethylene Oxide)

Author

Mukhopadhyay, Madhumita, Saha, Mou, Ray, Ruma, and Tarafdar, Sujata

Subjects
Condensed Matter - Materials Science
Abstract

Interactions of Poly (Ethylene Oxide) [PEO] and gamma irradiation of variable doses (1-30 kGy) on the thermal, crystalline and structural properties are investigated using DSC and FTIR technique. Two states of PEO, viz. powder (P-S-series) and solution (P-L-series) are subjected to irradiationand are castinto uniform film.DSC results revealed steady increment of crystallinity upto 20 kGy for P-S-series after which amorphous region increases till 30 kGy. Conversely, P-L-series shows much enhanced crystallinity retained within low regime of 7 kGy, followed by sharp declining trend till 30 kGy. DSC is also used to determine the multiple kinetic processes in an isoconversional PEO melting using Friedman differential analysis. Gamma irradiation is found to generate newer functional groups established from FTIR study. FTIR spectra of generated peaks viz. -C=O, -C=C- exhibit scission dominated irradiation induced in presence of air. Contribution of cross-linkage which is higher in liquid irradiation is also proved from FTIR. The studied observations of DSC and FTIR are correlated with polymer microstructures. Hence, selective irradiation dose could be determined with respect to the exposed state (solid or solution) of polymer and utilized to tailor the properties of PEO.

Published
2014

21. Impact of Tailored Gamma Irradiation on Pore Size and Particle Size of Poly[Ethylene Oxide]Films: Correlation with Molecular Weight Distribution andMicrostructural Study

Author

Mukhopadhyay, Madhumita, Saha, Mou, Ray, Ruma, and Tarafdar, Sujata

Subjects
Condensed Matter - Materials Science
Abstract

The structure and morphology of polymers are significantly altered upon exposure to high energy gamma irradiation. The present investigation reports the influence of such irradiation of doses in the range of 1 - 30 kGy on the particle size of Poly (Ethylene Oxide) [PEO] powder along with its correlation with molecular weight distribution. Pore-size distribution and overall porosity of the synthesized films prepared with irradiated and unirradiated PEO powder is also reported. The particle size of both unirradiated and irradiated PEO powders is found be in the range of 0.01 - 1000 micrometer. It is known that, variation in irradiation dose either generates particles of lower dimension through bond breakage i.e scission or higher dimension through cross-linkage. PEO films exhibit strong dependence of irradiation effect on pore size distribution and porosity. PEO films synthesized using both unirradiated and irradiated powders exhibit pore dimension in the range of 20 - 500 nm. The overall porosity of PEO films studied through BET adsorption technique initially increases with dose upto 3 kGy followed by linear decrease upto 30 kGy. Films cast with unirradiated PEO powder show multimodal pore size distribution, but perturbation with irradiation changes the modality to uni-or bimodal nature. The mentioned outcome of irradiation viz. particle and pore size variation is also correlated with PEO microstructures.The article demonstrates that, selective irradiation is capable of tailoring the pore-size within a definite regime thereby reducing the multimodal trait. The reported study may be relevant towards applications such as catalysis, sensing and filtration, where pore size distribution plays a crucial role.

Published
2014

48. Temperature and frequency dependent dielectric response of C3H7NH3PbI3: A new hybrid perovskite.

Author

Sengupta, Payal, Sadhukhan, Priyabrata, Ray, Apurba, Ray, Ruma, Bhattacharyya, Satyaranjan, and Das, Sachindranath

Subjects
ENERGY harvesting, PERMITTIVITY, DIELECTRIC relaxation, DIELECTRICS, SPACE charge, DIELECTRIC properties
Abstract

Propylammonium lead iodide (C3H7NH3PbI3), a promising hybrid perovskite, is successfully synthesized by a solgel technique. Structural, optical, and dielectric properties have been studied in detail. The dielectric constant, loss factor, electric modulus, and AC and DC conductivity of this hybrid perovskite exhibit strong temperature dependence over the frequency range of 10 Hz ≤ f ≤ 8 MHz. The Nyquist plot reveals the distinct contributions of grain and grain boundary to the total impedance. The dielectric constant is found to increase with temperature in the high frequency region. The modified Cole–Cole plot shows that the space charge and free charge conductivity increase with the elevation of temperature, whereas the relaxation time decreases with the rise in temperature. From the modified Kohlrausch–Williams–Watts equation, we perceived asymmetrical nature in electric modulus spectra at various temperatures, which corresponds to the non-Debye type nature of perovskite. It has also been found that, with the elevation of temperature, the imaginary part of electric modulus spectra shifts from the non-Debye type toward the Debye type nature, though failing to acquire exact Debye type response, and emerges as a semiconductor material. AC conductivity of PAPbI3 is illustrated on the basis of the correlated barrier hopping (CBH) mechanism. Activation energy estimated from both modulus spectra and DC conductivity matches well, affirming the similarity between relaxation behavior and conduction mechanism. Along with all these, PAPbI3 possesses a high dielectric constant associated with a small dielectric loss, making it a potential candidate for energy harvesting devices. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

49. Role of gamma irradiation on ion diffusion of PEO-NH4I based solid polymer electrolytes.

Author

Saha, Mou, Ballabh, Tapas Kumar, and Ray, Ruma

Subjects
IONIC conductivity, SOLID electrolytes, POLYELECTROLYTES, GAMMA rays, IRRADIATION, IONOPHORES, RELAXATION phenomena
Abstract

This article proposes using a suitable proportion of high-energy radiation for property enhancement in solid polymer electrolytes (SPEs). Here, the effect of gamma irradiation has been investigated in proton-conducting SPEs prepared from host polymer Poly(ethylene)Oxide and the salt NH4I. Gamma radiation, combined with variation in salt concentration, modifies the structural, thermal and electrical properties of the SPE. High energy radiation produces scission and/or cross-linking of polymer molecules and changes the effective crystalline /amorphous proportion of the system. The microstructural analysis and variation in physicochemical properties within the specified range of irradiation dose (1 – 49 kGy) have been studied systematically in this article. Before irradiation, only varying salt concentration, maximum DC ionic conductivity (2.31 × 10–6 S/cm) of this two-phase (PEO–NH4I) SPE system is achieved at 12wt% NH4I at room temperature. Application of gamma irradiation enhances the conductivity almost by two orders of magnitude (2.06 × 10–4 S/cm) at 37 kGy at room temperature. Associated dielectric properties and underlying relaxation phenomena show corresponding variations. The ion transport mechanism is analysed in terms of energy-induced ion dissociation, modified carrier ions (n) and ease of mobility (μ) of the carrier ions through a more amorphous polymer substrate. This competing effect between n and μ nicely explains the contribution to the enhancement of ionic conductivity due to gamma radiation in SPEs. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results