Nilotpal Ghosh

Bio: Nilotpal Ghosh is an academic researcher from Boston University. The author has contributed to research in topics: Magnetization & Transition temperature. The author has an hindex of 13, co-authored 42 publications receiving 548 citations. Previous affiliations of Nilotpal Ghosh include Visva-Bharati University & Indira Gandhi Centre for Atomic Research.

Critical properties of the double-exchange ferromagnet Nd(0.6)Pb(0.4)MnO(3)

Abstract: Results of a study of dc magnetization $M(T,H),$ performed on a ${\mathrm{Nd}}_{0.6}{\mathrm{Pb}}_{0.4}{\mathrm{MnO}}_{3}$ single crystal in the temperature range around ${T}_{C}$ (Curie temperature) which embraces the supposed critical region $|\ensuremath{\varepsilon}|=|T\ensuremath{-}{T}_{C}|{/T}_{C}l~0.05$ are reported. The magnetic data analyzed in the critical region using the Kouvel-Fisher method give the values for the ${T}_{C}=156.47\ifmmode\pm\else\textpm\fi{}0.06\mathrm{K}$ and the critical exponents $\ensuremath{\beta}=0.374\ifmmode\pm\else\textpm\fi{}0.006$ (from the temperature dependence of magnetization) and $\ensuremath{\gamma}=1.329\ifmmode\pm\else\textpm\fi{}0.003$ (from the temperature dependence of initial susceptibility). The critical isotherm ${M(T}_{C},H)$ gives $\ensuremath{\delta}=4.54\ifmmode\pm\else\textpm\fi{}0.10.$ Thus the scaling law $\ensuremath{\gamma}+\ensuremath{\beta}=\ensuremath{\delta}\ensuremath{\beta}$ is fulfilled. The critical exponents obey the single scaling equation of state $M(H,\ensuremath{\varepsilon})={\ensuremath{\varepsilon}}^{\ensuremath{\beta}}{f}_{\ifmmode\pm\else\textpm\fi{}}(H/{\ensuremath{\varepsilon}}^{\ensuremath{\beta}+\ensuremath{\gamma}}),$ where ${f}_{+}$ for $Tg{T}_{C}$ and ${f}_{\ensuremath{-}}$ for $Tl{T}_{C}.$ The exponent values are very close to those expected for the universality class of three-dimensional Heisenberg ferromagnets with short-range interactions.

Pressure-induced superconductivity in BaFe2As2 single crystal

Abstract: The evolution of pressure-induced superconductivity in single crystal as well as polycrystalline samples of BaF e2As2 have been investigated through temperature-dependent electrical resistivity studies in the 0–7 GPa pressure range. While the superconducting transition remains incomplete in the polycrystalline sample, a clear pressure-induced superconductivity with zero resistivity at the expense of magnetic transition, associated with spin density wave (SDW), is observed in the single-crystal sample. The superconducting transition temperature (TC) is seen to increase upto a moderate pressure of about ~1.5 GPa and decreases monotonically beyond this pressure. The SDW transition temperature TSDW decreases rapidly with increasing pressure and vanishes above ~1.5 GPa.

Cestocidal activity of Acacia auriculiformis

Abstract: The cestocidal activity of Acacia auriculiformis was evaluated using rats each harbouring a single adult worm of Hymenolepis diminuta. The ethanol extract (300 mg/kg/day) and the saponins (200 mg/kg/day) obtained from the funicles of A. auriculiformis, were administered orally to two groups each of 10 rats, respectively, on day 20 after oral inoculation with a single cysticercoid of H. diminuta. Adult worms were expelled within 5 days from rats treated with the ethanol extract and within 3 days from those treated with saponins. No appreciable side effects were observed in the treated rats.

Effect of rare-earth-site cations on the physical properties of La 0.7 − y Nd y Pb 0.3 Mn O 3 single crystals

Abstract: Single crystals of $La_{0.7–-y}Nd_yPb_{0.3}MnO_3$ with different y are grown by flux growth technique. The influence of change in average cationic radius $(\langle r_A\rangle)$ and cation size disorder $(\sigma^2)$ on the transport and magnetic properties of these crystals due to the presence of different cations (La and Nd) on the rare-earth sRd site is studied. Curie temperature $T_C$ and metal-insulator transition temperature $T_M_I$ are sensitive to the R site occupation. The temperature dependence of magnetization of $La_{0.7}Nd_yPb_{0.3}MnO_3$ is consistent with spin wave excitations according to the Bloch $T^{3/2}$ law at zero magnetic field limit. The Nd-based systems follow $T^{3/2}$ law only in a certain range of temperature and deviate at low temperatures, which is ascribed to a probably canted ordering of Nd and Mn moments with an antiferromagnetic component at very low temperatures. The values of spin stiffness constants and saturation magnetization vary systematically with changing occupation on the R site. Specific heat measurements of Nd containing samples show a Schottky-like anomaly at low temperature (below 15 K), which increases with the concentration of Nd ions in the lattice. It is concluded that the magnetic properties of manganites with Nd are affected by a tendency for magnetic ordering of the Nd ions.

Heisenberg-like critical properties in ferromagnetic Nd1-xPbxMnO3 single crystals

Abstract: Static magnetization for single crystals of insulating Nd0.85Pb0.15MnO3 and marginally conducting Nd0.70Pb0.30MnO3 has been studied around the ferromagnetic to paramagnetic transition temperature T-C. Results of measurements carried out in the critical range vertical bar(T - T-C)/T-C vertical bar <= 0.1 are reported. Critical exponents beta and gamma for the thermal behaviour of magnetization and susceptibility have been obtained both by modified Arrott plots and the Kouvel-Fisher method. The exponent delta independently obtained from the critical isotherm was found to satisfy the Widom scaling relation delta = gamma/beta + 1. For both compositions the values of exponents are consistent with those expected for isotropic magnets belonging to the Heisenberg universality class with short-range exchange in three dimensions. Correspondingly, the specific heat displays only a cusp-like anomaly at the critical temperature of these crystals which is consistent with an exponent alpha < 0. The results show that the ferromagnetic ordering transition in Nd1-xPbxMnO3 in the composition range 0.15 <= x <= 0.40 is continuous. This mixed-valent manganite displays the conventional properties of a Heisenberg-like ferromagnet, irrespective of the differing transport properties and in spite of low ordering temperatures T-C = 109 and 147.2 K for x = 0.15 and 0.30, respectively.

Superconductivity in iron compounds

Abstract: Kamihara and coworkers' report of superconductivity at ${T}_{c}=26\text{ }\text{ }\mathrm{K}$ in fluorine-doped LaFeAsO inspired a worldwide effort to understand the nature of the superconductivity in this new class of compounds. These iron pnictide and chalcogenide (FePn/Ch) superconductors have Fe electrons at the Fermi surface, plus an unusual Fermiology that can change rapidly with doping, which lead to normal and superconducting state properties very different from those in standard electron-phonon coupled ``conventional'' superconductors. Clearly, superconductivity and magnetism or magnetic fluctuations are intimately related in the FePn/Ch, and even coexist in some. Open questions, including the superconducting nodal structure in a number of compounds, abound and are often dependent on improved sample quality for their solution. With ${T}_{c}$ values up to 56 K, the six distinct Fe-containing superconducting structures exhibit complex but often comparable behaviors. The search for correlations and explanations in this fascinating field of research would benefit from an organization of the large, seemingly disparate data set. This review provides an overview, using numerous references, with a focus on the materials and their superconductivity.

The acute phase response and innate immunity of fish

Abstract: Tissue trauma or invasion by pathogens or parasites induce changes in the quantities of several macromolecules in animal body fluids These changes comprise one aspect of the acute phase response (APR), which in toto involves metabolic changes in several organ systems One clear indication of the response is the increase in synthesis and secretion by the liver of several plasma proteins, with simultaneous decreases in others These acute phase proteins (APP) function in a variety of defense-related activities such as limiting the dispersal of infectious agents, repair of tissue damage, inactivation of proteases, killing of microbes and other potential pathogens, and restoration of the healthy state Some APP are directly harmful to microbes, while others modify targets thus marking them for cell responses Some work alone while others contribute to cascades Proteins that are APP in mammals, and that have been identified in both teleosts and elasmobranchs include C-reactive protein, serum amyloid P, and several components of the Complement system Others reported in teleosts include transferrin and thrombin Of these, only CRP has been reported to increase in acute phase plasma In trout, a precerebellin-like protein is an APP with unknown functions A cDNA library enriched in fragments of transcripts that were more abundant in livers from fish undergoing an APR recently yielded sequences resembling 12 additional known APP, and as many others either not known to be APP, or not similar to others yet in public databases It appears that, as in mammals, hepatocytes are the prime source of APP in fish, and that pro-inflammatory cytokines induce transcription of their genes

A model of the development of the brain as a construct of the thyroid system.

Abstract: Thyroid hormone is essential for normal brain development. However, little is known about the molecular and cellular mechanisms that mediate thyroid hormone action on the developing brain or the developmental events selectively affected. Consequently, although a large number of environmental chemicals interfere with the thyroid system, there are few neurodevelopmental end points to recruit for toxicological studies. Therefore, my goal here is to review what is known about the relative timing of normal brain construction and thyroid system development, with special focus on the period of in utero development in humans and the comparable developmental period in laboratory rats. These data are presented as a timeline to aid in the identification of thyroid-sensitive end points in brain development and to highlight important data gaps. I discuss the known influence of certain synthetic chemicals on the thyroid system and include a brief review of the effects of developmental exposure to chemicals on thyroid system function. The relationship between the thyroid hormone and retinoic acid systems, as well as the thyroid hormone sensitivity of the developing cochlea, is also discussed.

Materials discovery by flux crystal growth: quaternary and higher order oxides.

Abstract: This Review highlights the application of high-temperature solutions for exploratory crystal growth and materials discovery of novel complex oxides. It provides an overview of the method of flux crystal growth of complex oxides and can function as a "how to" guide for those interested in oxide crystal growth. The most commonly used fluxes are discussed in terms of their applicability for dissolving specific elements and the typical reaction conditions are compiled. A large variety of recent quaternary and higher oxides that have been grown as crystals from fluxes are used to illustrate the power of the flux method to grow oxide crystals containing specific elements.