Origin of Large Dielectric Constant with Large Remnant Polarization and Evidence of Magnetoelectric Coupling in Multiferroic La modified BiFeO3-PbTiO3 Solid Solution

The presence of superlattice reflections and detailed analyses of the powder neutron and x-ray diffraction data reveal that La rich (BF$_{0.50}$-LF$_{0.50}$)$_{0.50}$-(PT)$_{0.50}$ (BF-LF-PT) has ferroelectric rhombohedral crystal structure with space group \textit{$R3c$} at ambient conditions. The temperature dependence of lattice parameters, tilt angle, calculated polarization $(P_{s})$, volume, and integrated intensity of superlattice and magnetic reflections show an anomaly around 170 K. Impedance spectroscopy, dielectric and ac conductivity measurements were performed in temperature range $473K \leq T \leq 573K$ to probe the origin of large remnant polarization and frequency dependent broad transitions with large dielectric constant near $T_c^{FE}$. Results of impedance spectroscopy measurements clearly show contributions of both grain and grain boundaries throughout the frequency range ($10^{3}$ Hz$\leq f\leq 10^{7}$ Hz). It could be concluded that the grain boundaries are more resistive and capacitive as compared to the grains, resulting in inhomogeneities in the sample causing broad frequency dependent dielectric anomalies. Enhancement in dielectric constant and remnant polarization values are possibly due to space charge polarization caused by piling of charges at the interface of grains and grain boundaries. The imaginary parts of dielectric constant ($\epsilon^{\prime\prime}$) Vs frequency data were fitted using Maxwell-Wagner model at $T_c^{FE}(\sim 523$K) and model fits very well with the data up to $10^{5}$ Hz. Magnetodielectric measurements prove that the sample starts exhibiting magnetoelectric coupling at $\sim 170$ K, which is also validated by neutron diffraction data.Comment: 20 pages, 10 figure

Emergency peripartum hysterectomy: a retrospective study of 7 years

Background: Emergency peripartum hysterectomy (EPH) is a rare but a lifesaving procedure done as a last resort to save life of mother. We conducted this study to know the incidence, leading causes, risk factors and complications of EPH.Methods: We conducted a retrospective analysis of all the patients who underwent EPH from January 2008 to December 2015 at SDMCM and H. All patients who underwent EPH from 22 weeks of gestation to 6 weeks postpartum were included in the study.Results: There were 21 emergency peripartum hysterectomies, with deliveries during the same period being 27271 and the rate of EPH was 0.7 per 1000 deliveries. Most common indication for EPH was uterine atony (38%), followed by uterine rupture (23.8%) and morbidly adherent placenta (19%). Most of the patients (47.6%) had previous cesarean deliveries. EPH was done following cesarean in 66.6%. Subtotal hysterectomy was done in 61.9%. Intra-operative urinary bladder injury was seen in 14.2% of the patients.Conclusions: Uterine atony and uterine rupture continues to be the most common causes for EPH in our population. Multiparity is an important risk factor among patients with rupture uterus. Cesarean delivery and repeat cesarean deliveries are the likely risk factors for EPH

Structural and magnetic phenomena in Ni53Mn25Al22 thin film prepared by rf magnetron sputtering

Magnetic and structural properties of Ni–Mn–Al thin films are investigated. It is demonstrated that the annealed film shows L21 phase at room temperature. Magnetometry measurements reveal that the annealed film is ferromagnetic and a first order transition in magnetization versus temperature measurement confirms that the martensite to austenite transition occurs around room temperature. Transmission electron microscopy measurements confirm that this structural change occurs just below room temperature. The splitting of Mn 2p3/2 level in x-ray photoelectron spectroscopy core level spectra of the annealed Ni–Mn–Al film, confirms that the origin of magnetism is definitely correlated with the local magnetic moment at the Mn atoms

Strain driven emergence of topological non-triviality in YPdBi thin films

Half-Heusler compounds exhibit a remarkable variety of emergent properties such as heavy-fermion behaviour, unconventional superconductivity and magnetism. Several of these compounds have been predicted to host topologically non-trivial electronic structures. Remarkably, recent theoretical studies have indicated the possibility to induce non-trivial topological surface states in an otherwise trivial half-Heusler system by strain engineering. Here, using magneto-transport measurements and first principles DFT-based simulations, we demonstrate topological surface states on strained [110] oriented thin films of YPdBi grown on (100) MgO. These topological surface states arise in an otherwise trivial semi-metal purely driven by strain. Furthermore, we observe the onset of superconductivity in these strained films highlighting the possibility of engineering a topological superconducting state. Our results demonstrate the critical role played by strain in engineering novel topological states in thin film systems for developing next-generation spintronic devices.Comment: 20 pages, 5 Figure

Evaluation of cellular prediction models using 900 MHz outdoor measurements and tuning of Lee model over Indian urban and suburban regions

The present study reports the field strength measurements of some GSM transmitters in the 900 MHz band located in the urban and suburban regions of Delhi in India. The measured signal levels converted into path loss values have been compared with the losses predicted from models such as Hata, Lee and COST 231 Walfisch and Ikegami. The prediction errors and standard deviations of the prediction errors have been deduced. Based on these results, Lee prediction method has been tuned and new model parameters have been derived. The model comparison is done in terms of statistical parameters such as root mean square error, coefficient of determination and average hit rate error