Browsing by Author "S. Dasgupta"

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Additional alkaloids of pachygone ovata
(1984) M. Abd El-Kawi; D.J. Slatkin; P.L. Schiff; S. Dasgupta; S.K. Chattopadhyay; A.B. Ray
Pachygone ovata (Menispermaceae), indigenous to the sandy seashores of southern India, is a woody climber whose fruits have been used as a rodenticide and fish poison. Chromatography of the extract of the roots resulted in the reisolation of the alkaloids liriodenine, coclaurine, trilobine (1), and magnoflorine and the isolation of stepholidine, coreximine, isoboldine, norjuziphine, and nortrilobine (2). Nortrilobine (2) is a new dibenzo-p-dioxin bisbenzylisoquinoline alkaloid whose structure was established by a consideration of spectral data and conversion to isotrilobine (3). © 1984, American Chemical Society. All rights reserved.
Chemical investigation of Pluchea lanceolata II. Identity of pluchine with betaine hydrochloride
(Birkhäuser-Verlag, 1968) B. Dasgupta; K. Basu; S. Dasgupta
[No abstract available]
Constituents of pachygone ovata and pharmacological action of its major leaf alkaloid
(1979) S. Dasgupta; A.B. Ray; S.K. Bhattacharya; R. Bose
Pachygone ovata (Menispermaceae) grows in the sandy sea shores of southern India, and its fruits are used as fish poison. Systematic fractionation of ethanolic extracts of the leaves, stems, and roots of the plant afforded five alkaloids: N-methylerotsparine (1), reticuline (2), liriodenine (5), trilobine (6), and coclaurine (7). In addition there was isolated a new amine oxide, reticuline N-oxide (3), and a cyclitol, characterized as (+)-quercitol (4). The pharmacological actions of reticuline were investigated. It showed central stimulant, hyperthermic, and spinal convulsant actions, the profile closely resembling that reported with thebaine. © 1979, American Chemical Society. All rights reserved.
Effect of ischaemia & aglycaemia on the synaptic transmission in neonatal rat spinal cord in vitro
(2003) Archana Jha; S. Dasgupta; S.B. Deshpande
Background & objectives: In vitro models of anoxia have revealed severe changes in neuronal functions after ischaemia but not after aglycaemia, although hypoglycaemia produced severe neuronal dysfunctions sometimes leading to coma. The present study was therefore undertaken to examine and compare the effects of aglycaemia with that of ischaemia on synaptic transmission in vitro. Methods: Spinal cord from the neonatal rat was isolated, hemisected and placed in a chamber perfused with standard physiological solution. The stimulation of a dorsal root elicited monosynaptic (MSR) and polysynaptic (PSR) reflex potentials in the segmental ventral root. The effects of suprefusing glucose free medium (aglycaemia) and superfusing glucose free and O2 free medium (ischaemia) were examined on these reflexes. Results: Superfusion of aglycaemic solution did not alter the magnitude of MSR or PSR in the first 15 min and subsequently there was a time-dependent depression of the reflexes (P < 0.05). The ischaemic solution depressed the reflexes in a time-dependent manner from the very beginning. The 50 per cent depression of the reflexes occurred around 25 and 15 min, for aglycaemia and ischaemia, respectively. In the presence of Mg2+, the aglycaemia-induced depression of MSR was completely blocked but the ischaemic response was attenuated partially as the reflex was abolished by 80 min. Interpretation & conclusion: The results of the present study indicate that the aglycaemia and ischaemia depressed the synaptic transmission to the same extent though there were differences in their onset and progress. Aglycaemia involves N-methyl-D-aspartate (NMDA) receptor-dependent (Mg2+sensitive) mechanism, while ischaemia-induced depression involves other mechanisms in addition to NMDA.
Estimation of global level density parameters using an unscented transform Kalman filter technique
(American Physical Society, 2024) Mahesh Choudhary; Aman Sharma; Namrata Singh; Punit Dubey; Mahima Upadhyay; Sriya Paul; Shweta Singh; Utkarsha Mishra; A. Kumar; S. Dasgupta; J. Datta
This study focuses on estimating the level density parameters for niobium (Nb) using the unscented transform Kalman filter technique. Niobium is widely utilized in accelerator components, particularly in superconducting radiofrequency cavities. To better understand the design of accelerator components and experimental setups, accurate information on both theoretical predictions and experimental results, including the uncertainties of nuclear reactions involving niobium, is essential. In this study, we have used the unscented transform Kalman filter technique to estimate level density parameters and their correlation matrix for Nb93(α,2n)Tc95 and Nb93(α,n)Tc96 reactions through the talys nuclear code. We have used the measured experimental nuclear reaction cross sections from this study to estimate the level density parameters for the above nuclear reactions. A comprehensive analysis of uncertainty propagation has been also conducted, encompassing both theoretical predictions and experimentally measured nuclear reaction cross sections. We have calculated uncertainties in both the theoretical calculations using the Monte Carlo method and experimentally measured reaction cross sections through covariance analysis for these nuclear reactions. We have also calculated the correlation matrix of the experimentally measured cross sections for the Nb93(α,n)Tc95 and Nb93(α,n)Tc96 nuclear reactions. © 2024 American Physical Society.
Excitation functions for natAg(α,x) reactions with detailed covariance analysis
(Elsevier B.V., 2024) Mahesh Choudhary; Namrata Singh; Mahima Upadhyay; Punit Dubey; Shweta Singh; Sriya Paul; Utkarsha Mishra; S. Dasgupta; J. Datta; A. Kumar
Natural silver targets were irradiated using an alpha particle beam to measure the activation cross sections of radioisotopes within the energy range of 23–40 MeV. The newly obtained cross section data, compared with previous experimental results, underline the importance of this work in the context of nuclear reactions and medical applications. Alpha particle induced reaction with natAg involved the production of radioisotopes such as 111In, 105Ag, 106mAg. In this study, we focused on calculating correlation matrices for the natAg(α,x) nuclear reactions. These matrices were generated by considering various interconnected variables, such as decay constants, particle number densities, γ-ray intensities and detector efficiencies for both monitor and sample nuclear reaction products. © 2024 Elsevier B.V.
Flavonoids of Elaeocarpus lanceofolius
(1976) A.B. Ray; S.C. Dutta; S. Dasgupta
4′-Methylmyricetin has been isolated from the leaves of Elaeocarpus lanceofolius together with myricetin and its 3-O-rhamnoside. This is the second report of the natural occurrence of a 4′-methyl ether of myricetin and the first in the family, Elaeocarpaceae. © 1976.
Measurement of alpha-induced reaction cross-sections for natZn with detailed covariance analysis
(Elsevier B.V., 2023) Mahesh Choudhary; Aman Sharma; Namrata Singh; A. Gandhi; S. Dasgupta; J. Datta; K. Katovsky; A. Kumar
The production cross-section of 68Ge, 69Ge, 65Zn and 67Ga radioisotopes from alpha-induced nuclear reaction with natZn have been measured using the stacked foil activation technique followed by the off-line γ-ray spectroscopy in the incident alpha energy range 14-37 MeV. The obtained nuclear reaction cross-sections are compared with previous experimental data available in the EXFOR data library, evaluated nuclear data from TENDL-2019 and theoretical results, calculated using TALYS nuclear reaction code. We have also performed the detailed uncertainty analysis for these nuclear reactions and their respective correlation metrics are presented. Since α-induced reactions are important in nuclear medicine and developing the nuclear reaction codes so needful corrections related to the coincidence summing factor and the geometric factor have been considered during the data analysis in the present study. © 2023 Elsevier B.V.
Measurement of alpha-induced reaction cross-sections on nat Mo with detailed covariance analysis
(Springer Science and Business Media Deutschland GmbH, 2022) Mahesh Choudhary; A. Gandhi; Aman Sharma; Namrata Singh; Punit Dubey; Mahima Upadhyay; S. Dasgupta; J. Datta; A. Kumar
In the present study we have measured the excitation functions for the nuclear reactions natMo(α,x)103Ru, natMo(α,x)97Ru, natMo(α,x)95Ru, natMo(α,x)96gTc, natMo(α,x)95gTc and natMo(α,x)94gTc in the energy range 9–32 MeV. We have used the stacked foil activation technique followed by the offline gamma-ray spectroscopy technique to measure the excitation functions. In this study we have also documented detailed uncertainty analysis for these nuclear reactions and their corresponding covariance matrix are also presented. The excitation functions are compared with the available experimental data from EXFOR data library and the theoretical prediction from TALYS nuclear reaction code. © 2022, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
Measurement of excitation functions for natCu(α, x) reactions with detailed covariance analysis
(Institute of Physics, 2023) Mahesh Choudhary; Aman Sharma; A. Gandhi; Namrata Singh; Punit Dubey; Mahima Upadhyay; Utkarsha Mishra; N.K. Dubey; S. Dasgupta; J. Datta; K. Katovsky; A. Kumar
The excitation functions of 66Ga, 67Ga, 65Zn and 64Cu radioisotopes produced via alpha-induced reaction on nat Cu were measured using a stacked foil activation method. The gamma-ray activity produced by the above mentioned radionuclides was measured using the HPGe detector. The covariance analysis was performed to quantify the measured cross-section uncertainties as well as the correlation between different alpha energy cross-sections. A covariance matrix and cross-sections for the natCu(α, x)66Ga, natCu(α, x)67Ga, natCu(α, x)65Zn and natCu(α, x)64Cu nuclear reactions in the projectile energy range of 15-37 MeV are reported in the present work. The measured reaction cross-sections are compared with the existing experimental data and theoretically simulated results from the TALYS code. © 2022 IOP Publishing Ltd.
Measurement of the excitation functions for natNi(α,x), reactions with detailed covariance analysis
(Springer, 2024) Namrata Singh; Mahesh Choudhary; A. Gandhi; Aman Sharma; Mahima Upadhyay; Punit Dubey; Rebecca Pachuau; S. Dasgupta; J. Datta; A. Kumar
We measured production cross sections of (Formula presented.) Co, (Formula presented.) Co, (Formula presented.) Co, (Formula presented.) Zn and (Formula presented.) Cu radioisotopes from (Formula presented.) -induced reactions of (Formula presented.) Ni by using a stacked-foil activation technique and offline (Formula presented.) -ray spectroscopy technique. The results were compared with the available experimental data as well as the theoretical calculations based on the TALYS (Formula presented.) 1.9 code. The present results in the energy region from 19 MeV to 40 MeV are in consistent with the existing experimental data and the calculated results. The measured cross-sections are reported along with their uncertainties and covariance matrix after a thorough uncertainty propagation using covariance analysis. The present experimental results will significantly contribute to enlarging the literature database for (Formula presented.) -induced reactions on (Formula presented.) Ni, leading to a variety of applications. © The Author(s), under exclusive licence to Società.
Production of 97Ru and 103Ru radionuclide from alpha-induced reaction on natMo
(Akademiai Kiado ZRt., 2024) Mahima Upadhyay; Mahesh Choudhary; Namrata Singh; A. Gandhi; Punit Dubey; S. Dasgupta; J. Datta; Yu. N. Kopatch; I.N. Ruskov; A. Kumar
The excitation functions of natMo(α, x)97Ru and natMo(α, x)103Ru reactions in the energy range of 10–22 MeV are determined using the stacked foil activation technique and offline γ-ray spectrometry. The correction for γ-self attenuation is performed in the present measurement. The theoretical predictions of cross-section for natMo(α, x)97Ru and natMo(α, x)103Ru reactions are calculated by TALYS. The results of the experiment are compared with the existing cross-section data available in the EXFOR database and different level density models by TALYS code. The uncertainty propagation in the measured cross-sections and correlation matrix using covariance analysis has been studied in this work. © Akadémiai Kiadó, Budapest, Hungary 2024.