Browsing by Author "S.K. Das"

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Alignment effects in the medium-spin level structure of Se 78
(American Physical Society, 2022) K. Mandal; A. Chakraborty; A.K. Mondal; U.S. Ghosh; Aniruddha Dey; Saumyajit Biswas; B. Mukherjee; S. Rai; S. Chatterjee; S.K. Das; S. Samanta; R. Raut; S.S. Ghugre; S. Bhattacharyya; S. Nandi; S. Bhattacharya; G. Mukherjee; S. Ali; A. Goswami; S. Mukhopadhyay; Krishichayan; R. Banik; R. Chakrabarti; V. Kumar; A. Kumar
The excited states of Se78 were populated using the Ge76(α,2n) fusion evaporation reaction. The deexcited gamma rays were detected using the Indian National Gamma Array (INGA) spectrometer comprising clover and low-energy photon spectrometer (LEPS) detectors. The ground state band of Se78 has been extended up to Ex = 8.5 MeV and J = 16â ; this excitation regime is very close to the π(1g9/22) crossing frequency. Several newly observed in-band and intraband transitions belonging to the other bands of Se78 have also been placed in the level scheme based on their coincidence relationships. From the newly identified E1 transitions, an enhancement in the B(E1)/B(E2) values with spin has been observed which indicates the onset of octupole correlations in the band structure built on the 3-, 2508-keV state. Persistence of triaxial shape up to the highest observed spin of the ground state band has been observed and the feature of successive 1g9/22 quasiparticle alignments due to protons and neutrons has been unveiled. The consequences arising due to the occurrence of the neutron 1g9/2 quasiparticle alignments in the other observed correlated band structures are also presented. The results are interpreted in terms of total Routhian surface (TRS) calculations and the level structure systematic of the neighboring nuclei. © 2022 American Physical Society.
Bamboo - A functionally graded composite-correlation between microstructure and mechanical strength
(2005) A.K. Ray; S. Mondal; S.K. Das; P. Ramachandrarao
Bamboo is supposed to be one of the best functionally gradient composite materials available. In a piece of bamboo, not only the number of fibres ('vascular bundles') but also the fibre quality varies from outer to inner-most periphery. It has been observed that near the outer periphery, within 1 mm 2 area, the number of fibres is approximately 8 whereas the same at the inner-most periphery is approximately 2. Again the cross-sectional shape of fibre at outer periphery is almost circular (diameter 0.14 mm) and compacted but at the inner-most periphery, a fibre (diameter of major axis 0.93 × diameter of minor axis 0.78 mm) has been sprayed, and contain matrix in it. This structural behaviour causes the variation of tensile strength, e.g., the strength of a fibre at the outer periphery is about 160 kg/mm2 and the same at the inner-most periphery is only 45 kg/mm2. It has also been observed that the matrix of bamboo can preferentially be removed from the fibre by alkali treatment. 10% NaOH can remove adhered matrix with little effect on fibres while 20% or stronger alkali reduces the strength of fibre. © 2005 Springer Science + Business Media, Inc.
Comparative studies of the ribosomes of enteric & nonenteric microorganisms by RNase I action & immunological method
(1977) M. Das; S.K. Das
[No abstract available]
Experience with plaque excision and dermal grafting in the surgical treatment of Peyronie's disease
(2008) N.K. Goyal; A. Kumar; S.K. Das; A.K. Pandey; G.K. Sharma; S. Trivedi; U.S. Dwivedi; Pratap Bahadur Singh
Introduction: Peyronie's disease is a common cause of sexual dysfunction. We assess the technique of plaque excision and dermal grafting for the treatment of Peyronie's disease. Methods: A total of 11 patients, aged 38-55 years, were operated for Peyronie's disease. All patients had stable plaque on the dorsum or dorsolateral aspect of the penile shaft. All patients had penile curvature, nine (81.8 percent) had painful erections, six (54.5 percent) had penile pain and three (27.3 percent) had erectile dysfunction. All suffered difficulty in intercourse. We performed plaque excision and dermal grafting. Main outcome measures were relief of penile pain, relief of painful erection, performance of satisfactory coitus and straight penis while erection. Results: All patients had relief of penile pain and painful erection. Nine (81.8 percent) patients had straight penis and had satisfactory coitus. Two (18.2 percent) patients suffered postoperative erectile dysfunction which was mild and responded to Sildenafil tabs. Conclusion: Although experience with this technique is limited, the initial results are encouraging. We found this technique feasible with satisfactory results.
Failure analysis of a passenger car coil spring
(2007) S.K. Das; N.K. Mukhopadhyay; B. Ravi Kumar; D.K. Bhattacharya
Investigation on the premature failure of suspension coil spring of a passenger car, which failed within few months after being put into service, has been carried out. Besides visual examination, other experimental techniques used for the investigation were (a) microstructural analysis and fractography by scanning electron microscopy (SEM), (b) inclusion rating by optical microscopy, (c) hardness testing, (d) residual stress measurement by X-Ray diffraction (XRD) and (e) instrumental chemical analysis. Inherent material defect in association with deficient processing led to the failure of the spring. © 2006.
Investigation of different possible excitation modes in neutron-rich As 78
(American Physical Society, 2020) A.K. Mondal; A. Chakraborty; K. Mandal; U.S. Ghosh; Aniruddha Dey; Saumyajit Biswas; B. Mukherjee; S. Rai; Krishichayan; S. Chatterjee; S.K. Das; S. Samanta; R. Raut; S.S. Ghugre; S. Rajbanshi; R. Banik; S. Bhattacharyya; S. Nandi; S. Bhattacharya; G. Mukherjee; S. Ali; A. Goswami; R. Chakrabarti; S. Mukhopadhyay; A.K. Sinha; V. Kumar; A. Kumar
The yrast and nonyrast level structure of the odd-odd As78 nucleus has been investigated using the standard ? ray spectroscopic techniques. The excited states of As78 were populated through Ge76(a,pn) fusion evaporation reaction at the incident beam energies of 30, 35, and 40 MeV. The deexciting gamma rays were detected with the Indian National Gamma Array spectrometer composed of Clover and low-energy photon spectrometer detectors. In addition to the extension of the previously known yrast positive-parity band up to Ex ˜ 2.7 MeV with J=11?, an excited dipole band-like structure based on the 7(-), 1243-keV state has also newly been established. Several weak transitions feeding the low-lying nonyrast states have newly been identified and placed in the level scheme. A highly irregular sequence of levels has been observed at the low-excitation regime suggesting the dominance of single-particle excitations. The experimental results have been compared with the predicted results from the large-scale shell-model calculations. The calculated results indicate an enhanced contribution from the intruder p(1g9/2) orbital to the wave function of the positive-parity yrast excited states with J=7?. This enhanced contribution is supposed to provide subsequent mild collectivity for the concerned states. The nature of collectivity has been extracted from the total Routhian surface calculations. Evidences for the possible persistence of the stapler like mechanism prevailing in the positive- and negative-parity level sequences are presented. © 2020 American Physical Society.
Investigation of the low- and medium-spin level structure in As 77
(American Physical Society, 2023) A.K. Mondal; A. Chakraborty; K. Mandal; U.S. Ghosh; Aniruddha Dey; Saumyajit Biswas; B. Mukherjee; Krishichayan; S. Chatteerjee; S.K. Das; S. Samanta; R. Raut; S.S. Ghugre; S. Mukhopadhyay; S. Rajbanshi; R. Banik; S. Bhattacharyya; S. Nandi; S. Chakraborty; S. Bhattacharya; G. Mukherjee; S. Ali; A. Goswami; R. Chakrabarti; A. Kumar; R. Goswami
The low- and medium-spin level structure of As77 nucleus has been investigated using the Ge76(α,p2n) fusion evaporation reaction and the standard in-beam γ ray spectroscopic technique. The deexciting γ rays were detected with the Indian National Gamma Array spectrometer comprising Clover and LEPS detectors. The previously known 9/2+ yrast positive-parity band, based on the π(g9/2) configuration, has been extended to the excitation energy of Ex≈7.5 MeV with Jπ=(33/2+). An extension of the high-lying negative-parity band, based on the π[(g9/2)] - ν[(g9/2)(fp)] configuration, has been made up to Ex≈5.1 MeV, Jπ=(25/2-). The yrast positive-parity α=-1/2 signature partner band has newly been identified and the occurrence of large signature splitting associated with the partner bands have been observed. A quasi-γ vibrational band structure built on the nonyrast 13/2+ state has also newly been established. The experimental findings have been interpreted on the basis of the predicted results from the total Routhian surface, particle plus triaxial-rotor model, and shell-model calculations. The band crossing phenomena correlated to the ν(g9/2) alignment and the perseverance of triaxial shape up to the highest observed excitation regime of the 9/2+ yrast positive-parity band have been discussed. The evidence for the possible onset of the stapler-like mechanism prevailing in the high-lying negative-parity band structure are presented. © 2023 American Physical Society.
Microstructural characterization of bamboo
(2004) A.K. Ray; S.K. Das; S. Mondal; P. Ramachandrarao
The microstructural properties of bamboo were analyzed. A typical bamboo specimen was air dried in open atmosphere after collection and then cut into small pieces. The microstructural characterization of the gold coated bamboo specimen were carried out using scanning electron microscope (SEM). The fracture of the vascular bundle show that the fibers contains many sclerenchyma cells. The wall thickness in between two sclerenchyma cells ranges from 1 to 5 μm and the width of the same varies from 10 to 20 μm.
Morphosynthesis of calcium carbonate in poly(vinylalcohol)
(2002) A. Sinha; A. Agrawal; S. Nayar; S.K. Das; P. Ramachandrarao
In situ synthesis of calcium carbonate particles has been carried out in poly(vinylalcohol) solution and physical gels under free drift conditions. A multitude of morphologies, ranging from spherulites to helical structures of calcite, are produced by systematically varying the polymer concentration both in solution as well as in gels.
Ocular manifestations of leukaemia
(1983) D. Kumar; V.P. Singh; V. Thakur; H.V. Neema; S.K. Das
[No abstract available]
Radiocytogenetical Studies on Solanum. I. Meiotic abnormalities
(1989) S.K. Das; S.K. Roy
Meiosis is normal in control plants. Radiation induced meiotic abnormalities increased with increased exposures to gamma-rays. The chromosomal aberrations included stickiness, clumping, precocious separation, bridges, laggards etc. Pollen sterility increased with dose and was directly proportional to meiotic irregularities. The percentage frequencies of anomalies were more numerous in M1 than M2 due to genetic recovery or elimination of the defectives. © 1989, Japan Mendel Society, International Society of Cytology. All rights reserved.