Browsing by Author "S. Ray"

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High spin states in Pm139
(American Physical Society, 2009) A. Dhal; R.K. Sinha; L. Chaturvedi; P. Agarwal; S. Kumar; A.K. Jain; R. Kumar; I.M. Govil; S. Mukhopadhyay; A. Chakraborty; Krishichayan; S. Ray; S.S. Ghugre; A.K. Sinha; R. Kumar; R.P. Singh; S. Muralithar; R.K. Bhowmik; S.C. Pancholi; J.B. Gupta
The odd mass nucleus Pm139 has been studied to high spins through the Cd116(Al27,4n)Pm139 reaction at an incident beam energy of 120 MeV. The de-exciting γ-rays were detected using an array of 12 Compton suppressed Ge detectors. A total of 46 new levels have been proposed in the present work as a result of the observation of 60 new γ-rays. Four new bands including a ΔJ=1 sequence have been identified and all the earlier reported bands, other than the yrast band, have been extended to higher spins and excitation energy. The spin assignments for most of the newly reported levels have been made using the observed coincidence angular anisotropy. Tilted axis cranking calculations support the interpretation of two of the observed magnetic dipole sequences as examples of magnetic rotational bands. © 2009 The American Physical Society.
High-spin states in the odd-odd nucleus146Tb
(American Physical Society, 2004) Krishichayan; A. Chakraborty; S.S. Ghugre; R. Goswami; S. Mukhopadhyay; N.S. Pattabiraman; S. Ray; A.K. Sinha; S. Sarkar; P.V. Madhusudhana Rao; U. Garg; S.K. Basu; B.K. Yogi; L. Chaturvedi; A. Dhal; R.K. Sinha; M. Saha Sarkar; S. Saha; R. Singh; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
The odd-odd 146Tb nucleus has been investigated using the 115In(34S,3n) reaction at 140 MeV incident energy using an array of eight Compton-suppressed Clover detectors. Based on the observed γ- γ coincidences, the level structure of 146Tb has been extended up to Ex∼ 10 MeV. Linear polarization measurements have been combined with angular correlations of the observed γ rays to assign the electromagnetic nature to the transitions. Probable origin of a cascade of M1 transitions observed around 8 MeV excitation energy has been discussed.
Identification of Leishmania donovani antigens stimulating cellular immune responses in exposed immune individuals
(2006) P. Tripathi; S. Ray; S. Sunder; A. Dube; S. Naik
Human visceral leishmaniasis (VL), also known as kala azar (KA) in India, is a systemic progressive disease caused by Leishmania donovani. In VL, Th1 responses correlate with recovery from and resistance to disease and resolution of infection results in lifelong immunity against the disease. However, recent data suggest an important role for interleukin (IL)-10 in maintaining the resistant state. We evaluated whole cell extract (WE) and 11 antigenic fractions [F1-F11, molecular weight (MW) range of 139-24.2 kDa] from L. donovani (2001 strain, a fresh field isolate from Bihar), for their ability to induce in vitro T cell proliferation and production of interferon (IFN)-γ, interleukin (IL)-12, IL-10 and IL-4 by peripheral blood mononuclear cells (PBMCs) of exposed immune individuals (14 patients with history of VL, 10 household endemic contacts) and 20 non-endemic healthy controls. Twenty-one of 24 exposed individuals and no healthy controls showed proliferative response to WE. Whole-extract activated IFN-γ, IL-12, IL-10 levels were higher in the exposed group than in controls; IL-4 was not detectable in any of the samples. Among 21 responders to WE, frequent proliferative responses were seen to fractions F1-F4 (MW > 64.2 kDa) and none to fractions F5-F11; fractions F1-F11 stimulated comparable levels of IFN-γ and IL-12 while IL-10 levels were higher in response to F5-F11 compared to F1-F4. These data demonstrate the presence of immunostimulatory antigens in the high MW fractions of whole L. donovani antigen. However, these fractions do not stimulate a Th1 response and produce variable amounts of IFN-γ and the regulatory cytokine, IL-10. Hence, these high MW immunostimulatory fractions need to be evaluated in greater depth for their possible role as protective antigens. © 2005 British Society for Immunology.
Intense green photoluminescence and upconversion-based intrinsic optical bistability in Ho3+/Yb3+ codoped CaSc2O4 and upconversion in Ho3+/Yb3+ codoped CaY2O4 phosphors
(Elsevier B.V., 2022) P. Tadge; I.R. Martín; S.B. Rai; S. Sapra; T.M. Chen; V. Lavín; R.S. Yadav; S. Ray
The present study details the downshifting, frequency upconversion and intrinsic optical bistability in CaSc2O4:Ho3+/Yb3+ and upconversion in CaY2O4:Ho3+/Yb3+ phosphors synthesized by a complex-based precursor solution method. The X-ray powder diffraction confirms the formation of highly crystalline phosphors with pure orthorhombic phase. Fourier transform infrared studies of synthesized phosphors show vibrational bands due to the presence of Ca–O, Sc–O and Y–O groups. The diffuse reflectance spectra show a number of bands in the UV–vis–NIR regions due to presence of Ho3+ and Yb3+ ions. The values of optical band gap (Eg) are found to be 5.69 eV and 5.58 eV for the Ho3+/Yb3+ codoped CaSc2O4 and CaY2O4 phosphors, respectively. The Ho3+/Yb3+ codoped CaSc2O4 phosphors display intense green downshifting emission upon 454 nm excitations. The lifetime of green luminescence of CaSc2O4:Ho3+/Yb3+ phosphors with varied Yb3+ concentrations have also been measured. The decay curves show a non-exponential nature fitted to the Inokuti-Hirayama model and the energy transfer microscopic parameters have been also calculated. The Ho3+/Yb3+ co-doped CaSc2O4 and CaY2O4 phosphors display intense green alongwith weak blue, red, and near-infrared upconversion (UC) emissions upon 980 nm excitations. The spectral color purity (Sgr) of CaSc2O4:Ho3+(1%)/Yb3+(5%) phosphor is calculated to be 0.78. Importantly, the variation of pump power generates intrinsic optical bistability (IOB) in the CaSc2O4:Ho3+(1%)/Yb3+(5%) phosphor for the green emission, which is not observed in the CaY2O4:Ho3+(1%)/Yb3+(5%) phosphor. Therefore, the Ho3+/Yb3+ co-doped CaSc2O4 phosphor could potentially be used in UC-based devices, optical memory devices, optical gates, optical transistors and switching devices for optical communications. © 2022 Elsevier B.V.
Lifetime measurements of microsecond isomers in the N=48 nuclei 88Zr and90Mo using recoil-isomer tagging
(American Physical Society, 2004) A. Chakraborty; Krishichayan; S.S. Ghugre; R. Goswami; S. Mukhopadhyay; N.S. Pattabiraman; S. Ray; A.K. Sinha; S. Sarkar; P.V. Madhusudhana Rao; U. Garg; S.K. Basu; L. Chaturvedi; A. Dhal; R.K. Sinha; I.M. Govil; M.B. Chatterjee; M. Saha Sarkar; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
The recoil-isomer tagging technique has been used to study the isomeric states of nuclei in the vicinity of the N=50 shell closure. The nuclei of interest were separated from the projectilelike nuclei and other evaporation residues and transported to the focal plane of a recoil separator. The decay of the tagged isomer was studied at the focal plane using a high-purity Ge detector. The prompt transitions feeding the isomer were detected in an array of Clover Ge detectors placed around the target. The measured half-lives of the 8+ isomers in 88Zr and 90Mo are 1.41 (-0.09)(+0.12) μs and 1.17(-0.07) (+0.19), respectively. The corresponding transition probabilities are in reasonable agreement with the predictions of shell model calculations. The systematics of effective charges (ep and en) for N=48 nuclei are qualitatively understood in these calculations.
Plasma cortisol in glaucoma
(1977) S. Ray; K.S. Mehra; S. Misra; R. Singh
Plasma cortisol level and intraocular tension were determined diurnally in 40 normal and 40 glaucomatous patients at 8 AM and 8 PM. It was observed that (1) plasma cortisol level was higher in glaucomatous patients at both the periods; (2) the diurnal variation in plasma cortisol was parallel to diurnal variation in intraocular tension in both glaucomatous and normal persons; and (3) the diurnal variation in plasma cortisol level also was more marked in glaucomatous patients as compared to normal persons.
Spectroscopy of Nb90 at high spin
(2005) A. Chakraborty; Krishichayan; S.S. Ghugre; R. Goswami; S. Mukhopadhyay; N.S. Pattabiraman; S. Ray; A.K. Sinha; S. Sarkar; P. V. Madhusudhana Rao; U. Garg; S.K. Basu; M.B. Chaterjee; M. Saha Sarkar; L. Chaturvedi; A. Dhal; R.K. Sinha; I.M. Govil; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
Excited states of Nb90 were investigated via prompt and delayed γ decays and the recoil-isomer tagging technique. The level scheme of Nb90 has been extended up to J=19 and Ex=8.4 MeV. Half-lives of the 11- and 17/2- isomeric levels in Nb90,91 were measured to be 0.47±0.01 and 3.3±0.4 μs, respectively. The results are compared with the predictions of large-basis shell model calculations. The effects of truncation of the valence model space on the calculated results are discussed. © 2005 The American Physical Society.
Spin-parity measurements in the neutron-rich N ∼ 20 34P and 36S nuclei
(2006) Krishichayan; A. Chakraborty; S. Mukhopadhyay; S. Ray; N.S. Pattabiraman; S.S. Ghugre; R. Goswami; A.K. Sinha; S. Sarkar; U. Garg; P.V. Madhusudhana Rao; S.K. Basu; B.K. Yogi; L. Chaturvedi; A. Dhal; R.K. Sinha; M. Saha Sarkar; S. Saha; R. Singh; R.K. Bhowmik; A. Jhingan; N. Madhavan; S. Muralithar; S. Nath; R.P. Singh; P. Sugathan
Yrast and near-yrast energy levels in the neutron-rich N ∼ 20 nuclei 34P, 36S were populated using transfer/deep-inelastic processes following the 34S + 115In reaction at an incident energy of 140MeV. The use of a multi-clover array has facilitated polarization measurements of the observed γ-rays and necessitated some changes in the previously known level scheme. The observation of the negative-parity levels in these nuclei on the periphery of the "island of inversion" is indicative of the influence of the intruder orbitals on the level structure at low spins. Shell-model calculations indicate that the inclusion of the orbitals from the upper pf shell is important even for the low-lying positive-parity states.