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426 results on '"Mohan, Anita"'

6. Emergence of Griffiths phase, re-entrant cluster glass,metamagnetic transition and field induced unusual spin dynamics in Tb2CoMnO6

Author

Anand, Khyati, Pal, Arkadeb, Singh, Prajyoti, Alam, Md., Joshi, Amish G, Mohan, Anita, and Chatterjee, Sandip

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

The structural and magnetic properties of double perovskiteTb2CoMnO6 have been investigated. Electronic structure analysis by XPS study reveals the presence of mixed oxidation state (Mn4+/Mn3+ and Co2+/Co3+) of B-site ions. The dc and ac magnetization measurements reveal different interesting phases such as Griffith phase, re-entrant spin glass, metamagnetic steps, Hopkinson like peak and also unusual slow relaxation. The M-H curve indicates the presence of competing AFM/FM interactions. The disorder in Tb2CoMnO6 leads to spin frustration at low temperature giving rise to the re-entrant spin glass. Moreover, the field-dependent ac susceptibility studies unraveled the presence of Hopkinson like peak associated with the domain wall motion and the large anisotropy field. The further study yielded that the relaxation associated with this peak is unusually slow., Comment: 30 pages, 10 figures

Published
2019

7. Understanding anatomical perfusion and strategies to optimize vascularity in free tissue transfer for autologous breast reconstruction using the Deep Inferior Epigastric Artery Perforator (DIEP) flap

Author

Mohan, Anita and Nicholson, Mich

Subjects
618.1, breast reconstruction, flap, microsurgery, preconditioning, flap anatomy, perforator flap
Abstract

Breast cancer is the commonest cancer that affects women in the United Kingdom (UK). Autologous free tissue transfer using abdominal tissue remains an excellent option for breast reconstruction following mastectomy, given greater availability of tissue and lower donor site morbidity associated with muscle-sparing approaches (perforator-based). This research evaluated microvascular anatomy of Deep Inferior Epigastric Artery Perforator (DIEP) flaps, the role of linking vessels on dynamic perfusion in bilateral breast reconstruction and strategies to augment flap vascularity. For the ex-vivo anatomical studies, three and four-dimensional computed tomographic angiography (CTA) were used to evaluate patterns of the microvascular blood supply of individual perforators and corresponding perfusion patterns in the hemi-abdomen. This was combined with an in-vivo clinical study of women undergoing bilateral DIEP breast reconstruction following mastectomy, where both preoperative CTA and intra-operative Laser-Assisted Indocyanine Green Fluorescence Angiography (LA-ICGFA) were used to evaluate perforator anatomy and dynamic perfusion zones of individual perforators. Finally, an experimental in-vivo animal model was used to investigate strategies of pretreatment of perforator flaps with negative pressure wound therapy to augment vascularity of perforator flaps prior to flap harvest. The vascular territories of individual perforator within hemi-DIEP flaps demonstrated variable patterns with unique patterns of perfusion. Concepts including early capture of large calibre direct linking vessels to adjacent perforators or the superficial inferior epigastric artery (SIEA) territories, mostly found in the supra-scarpa’s and subdermal layers of the flap, played a key role in defining overall perfusion area and dynamic perfusion patterns not previously described. In conclusion, this work reported the characterization of the microvasculature within abdominal based perforator flaps to better understand the variation in dynamic perfusion. It also explored the potential role of non-invasive negative pressure treatment to augment flap perfusion that may be translated into the clinical setting.

Published
2020
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17. Estimation of Plasma Properties and Magnetic Field in a Prominence-like Structure as Observed by SDO/AIA

Author

Dwivedi, Bhola N., Srivastava, A. K., and Mohan, Anita

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

We analyze a prominence-like cool plasma structure as observed by Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We perform the Differential Emission Measure (DEM) analysis using various filters of AIA, and also deduce the temperature and density structure in and around the observed flux-tube. In addition to deducing plasma parameters, we also find an evidence of multiple harmonics of fast magnetoacoustic kink waves in the observed prominence-like magnetic structure. Making use of estimated plasma parameters and observed wave parameters, under the baseline of MHD seismology, we deduce magnetic field in the flux-tube. The wave period ratio P1/P2 = 2.18 is also observed in the flux-tube, which carries the signature of magnetic field divergence where we estimate the tube expansion factor as 1.27. We discuss constraints in the estimation of plasma and magnetic field properties in such a structure in the current observational perspective, which may shed new light on the localized plasma dynamics and heating scenario in the solar atmosphere., Comment: 3 Pages; Paper for the proceedings of IAU Symposium 300 : Nature of prominences and their role in space weather; Eds. B. Schmieder, J.M. Melherbe, S. Wu

Published
2013
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18. Spontaneous exchange bias and large dielectric constant in Bi0.8Tb0.2Fe0.8Mn0.2O3 multiferroic.

Author

Kumari, Seema, Anand, Khyati, Alam, Mohd, Ghosh, Labanya, Ghosh, Swayangsiddha, Gupta, Prince, Singh, Rahul, Jain, A. K., Yusuf, S. M., Ghosh, Anup K., Mohan, Anita, and Chatterjee, Sandip

Subjects
PERMITTIVITY, THERMOREMANENT magnetization, EXCHANGE bias, TERBIUM, SPACE groups, MAGNETIC properties
Abstract

The structural, dielectric, and magnetic properties of Bi0.8Tb0.2Fe0.8Mn0.2O3 have been studied in detail. A structural shift from rhombohedral (space group R3c) to orthorhombic (space group Pn21a + Pnma) phase is observed with doping. The substitution of Mn and Tb gives a very large value of the dielectric constant. It has been demonstrated that the observed spontaneous exchange bias is larger than the conventional exchange bias at room temperature. Moreover, doping reduces the Neel temperature from 643 to 521 K and magnetization increases. Thermoremanent magnetization studies at room temperature show that the system is composed of an interfacial layer of an antiferromagnetic core and a two-dimensional diluted antiferromagnet shell with a net magnetization under the field. Furthermore, the system's reasonable HEB and HC values at room temperature make it intriguing and appealing for a variety of multifunctional devices. [ABSTRACT FROM AUTHOR]

Published
2022
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31. Spin-phonon coupling and giant dielectric constant in Bi0.5La0.5Fe0.4Al0.1Mn0.5O3.

Author

Kumari, Seema, Alam, Mohd, Dixit, Srishti, Ghosh, Labanya, Ghosh, Swayangsiddha, Gupta, Prince K., Rohit, Jayraj, Anand, Khyati, Rana, Nabakumar, Mukherjee, Suchandra, Mohan, Anita, Banerjee, Aritra, and Chatterjee, Sandip

Abstract

In the present article, we report the magnetic, dielectric, and structural properties of the perovskite Bi0.5La0.5Fe0.4Al0.1Mn0.5O3. The structural analysis shows that this system crystallizes in a disordered orthorhombic phase with the space group Pnma. We found two consecutive magnetic transitions at 42 K and 147 K which have been suggested to be associated with the spin-glass and long-range ordering transitions, respectively. Further, temperature-dependent Raman spectra shows that this system has a spin-phonon coupling. Moreover, the dielectric measurement suggests that this system has a large dielectric constant at ambient temperature. Additionally, the dielectric spectrum suggests an unusual frequency-dependent step-like trend and the presence of weak relaxor ferroelectricity in the system. Thus, the presence of such multiple interesting characteristics suggests that Bi0.5La0.5Fe0.4Al0.1Mn0.5O3 can be used as spintronic devices and high dielectric applications. [ABSTRACT FROM AUTHOR]

Published
2023
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42. Enhancement of Multiferroic and Optical Properties in BiFeO3 Due to Different Exchange Interactions Between Transition and Rare Earth Ions.

Author

Kumari, Seema, Anand, Khyati, Alam, Mohd, Ghosh, Labanya, Dixit, Srishti, Singh, Rahul, Jain, Anil Kumar, Yusuf, Seikh Mohammad, Gautam, Chetna, Ghosh, Anup K, Mohan, Anita, and Chatterjee, Sandip

Subjects
RARE earth ions, OPTICAL properties, NEUTRON diffraction, MAGNETIC moments, NEUTRON measurement
Abstract

An experimental analysis of the Bi0.90Tb0.1Fe0.90Mn0.1O3 system synthesized via the solid‐state method is presented in this report. UV–visible measurements are carried out and a smaller bandgap (i.e., semiconductor‐type behavior) is obtained. The structural phase of the present system is analyzed with X‐ray diffraction and neutron diffraction measurement. Structural‐phase analysis reveals that the system contains two nuclear phases (rhombohedral structure [R3c space group] with orthorhombic [Pn21a space group]). Moreover, also more bending in the bond angle is found, and the existence of a magnetic phase with a nuclear phase for the Bi0.90Tb0.1Fe0.90Mn0.1O3 system is also confirmed by neutron diffraction. The magnetic moment versus temperature (M–T) curve demonstrates that the system's Néel transition temperature is at 568 K. The magnetization data show enhancement in the magnetic property by displaying the weak ferromagnetic‐type behavior at room temperature in the magnetic field versus magnetic moment (M–H) curve as compared to the parent compound. From dielectric measurement, the dielectric constant increases while the loss decreases. [ABSTRACT FROM AUTHOR]

Published
2023
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48. Hand Flaps

Author

Chim, Harvey, Ng, Zhi Yang, Carlsen, Brian T., Mohan, Anita T., and Saint-Cyr, Michel

Published
2014
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