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A complex interplay of different energy scales involving Coulomb repulsion, spin-orbit coupling, and Hund's coupling energy in 2D van der Waals (vdW) material produces a novel emerging physical state. For instance, ferromagnetism in vdW charge transfer insulator CrGeTe_{3} provides a promising platform to simultaneously manipulate the magnetic and electrical properties for potential device implementation using few nanometers thick materials. Here, we show a continuous tuning of magnetic and electrical properties of a CrGeTe_{3} single crystal using pressure. With application of pressure, CrGeTe_{3} transforms from a ferromagnetic insulator with Curie temperature T_{C}∼66 K at ambient condition to a correlated 2D Fermi metal with T_{C} exceeding ∼250 K. Notably, absence of an accompanying structural distortion across the insulator-metal transition (IMT) suggests that the pressure induced modification of electronic ground states is driven by electronic correlation furnishing a rare example of bandwidth-controlled IMT in a vdW material.

The zero field 53Cr nuclear magnetic resonance was measured at low temperatures to investigate the interactions in the bond-frustrated S = 3/2 Heisenberg helimagnet ZnCr2Se4. A quadratic decrease of the sublattice magnetization was determined from the temperature dependence of the isotropic hyperfine field. We calculated the magnetization using linear spin wave theory for the incommensurate spiral spin order and compared this outcome with experimental results to estimate the coupling constants. The hyperfine fields at Cr and Se ions provide evidences that the spin polarization of Cr ions is transferred to neighboring Se ions due to the covalent bonding between them, resulting in reduced magnetic moment in the Cr ion. This observation indicates that the Jahn-Teller effect, which leads to distortion inducing spin-lattice coupling, is not completely missing in ZnCr2Se4.

There is a marked inclination towards cesarean sections as the preferred mode of delivery in parturients with COVID-19 disease. However, the challenges associated with planning and performing a surgery in the COVID-19 setup are considerable. These factors may lead to widespread changes in obstetric decision-making, operative planning, and perioperative outcomes. Thus, our study aimed to study the clinical and logistical factors involved in cesarean sections in COVID-19 parturients.This was a retrospective observational study performed at a dedicated COVID-19 tertiary care center in India. All women undergoing cesarean section in the specially earmarked operating room between 1A total of 44 women underwent cesarean section during the study period, with elective and emergency surgeries numbering 22 each. No indication, apart from COVID-19 status, was listed in over one-fourth of the women (13/44). The most common preoperative comorbidity was hypothyroidism (12/44). Median surgical duration was 117.5 min (IQR 100-133), with a median of 7.5 (IQR 6-8.25) healthcare personnel in the OT. Over one-fourth (12/44) of the delivered babies had low birth weight, while 4.5% (2/44) tested positive for SARS-CoV-2.COVID-19 status alone continues to be a common indication for cesarean section. Operative time is increased, but the number of healthcare personnel involved can be trimmed with proper planning. Maternal and fetal outcomes are largely positive, with low transmission rates, but a considerable proportion of low-birth-weight neonates.

In order to understand the superconducting gap nature of a $$\hbox {2H-Pd}_{0.08} \hbox {TaSe}_2$$ 2H-Pd 0.08 TaSe 2 single crystal with $$T_{c} = 3.13 \text { K}$$ T c = 3.13 K , in-plane thermal conductivity $$\kappa $$ κ , in-plane London penetration depth $$\lambda _{\text {L}}$$ λ L , and the upper critical fields $$H_{c2}$$ H c 2 have been investigated. At zero magnetic field, it is found that no residual linear term $$\kappa _{0}/T$$ κ 0 / T exists and $$\lambda _{\text {L}}$$ λ L follows a power-law $$T^n$$ T n (T: temperature) with n = 2.66 at $$T \le \frac{1}{3}T_c$$ T ≤ 1 3 T c , supporting nodeless superconductivity. Moreover, the magnetic-field dependence of $$\kappa _{0}$$ κ 0 /T clearly shows a shoulder-like feature at a low field region. The temperature dependent $$H_{c2}$$ H c 2 curves for both in-plane and out-of-plane field directions exhibit clear upward curvatures near $$T_c$$ T c , consistent with the shape predicted by the two-band theory and the anisotropy ratio between the $$H_{c2}$$ H c 2 (T) curves exhibits strong temperature-dependence. All these results coherently suggest that $$\hbox {2H-Pd}_{0.08} \hbox {TaSe}_2$$ 2H-Pd 0.08 TaSe 2 is a nodeless, multiband superconductor.

We report an unconventional class of pressure-induced quantum phase transitions, possessing two bicritical points at 6.25 GPa in URhSn. This unique transformation accompanies a Fermi surface reconstruction, demarcating competing ordered phases suitably described with a localized and itinerant description of the magnetic $5f$ electrons. Ferromagnetic fluctuations over a wide range of temperatures and pressures in the pressure-induced low temperature phase are evidenced by a robust ${T}^{5/3}$ temperature dependence of resistivity up to 11 GPa, which is a characteristic of an elusive marginal Fermi-liquid state.

The effect of high pressure (up to 8 GPa) on normal and superconducting state properties of PrFeAsO0.6F0.12, an 1111-type iron based superconductor close to optimal doped region, has been investigated by measuring the temperature dependence of resistivity. Initially, the superconducting transition temperature (T c ) is observed to increase slowly by about 1 K as pressure (P) increases from 0 to 1.3 GPa. With further increase in pressure above 1.3 GPa, T c decreases at the rate of ~1.5 K/GPa. The normal-state resistivity decreases monotonically up to 8 GPa. We have also measured the pressure dependence of magnetization (M) on the same piece of PrFeAsO0.6F0.12 sample up to 1.1 GPa and observed T c as well as the size of the Meissner signal to increase with pressure in this low-pressure region. In contrast, for an over-doped PrFeAsO0.6F0.14 sample, magnetization measurements up to 1.06 GPa show that both T c and the Meissner signal decrease with pressure. The present study clearly reveals two distinct regions in the dome-shaped (T c -P) phase diagram of PrFeAsO0.6F0.12.

Recently personal security has become a sensitive issue. Small kids, ladies, as well as aged people need to have their secure against kidnapping, rape, chain snatching respectively. There are different areas & scopes of security. Recent social incidents gave us motivation to develop personal security system. Kids, aged people & ladies mostly not able to fight to criminal for self security. Sometime government security may not give on time support.. Most of the time, citizens are very much reluctant to help any victim of such incidents. Hence smart personal Security system gives us reliable solution to overcome such problem. For developing smart system two factors has been considered i.e. prevention of incident & cure of incident. Best Efforts are taken to have defense for user by this smart system, as well as alarming communication. Pulse rate sensor, pressure switches, & manual switches contribution has been considered. For alarming, defensive situation.

In the past years, Wireless Sensor Networks (WSNs) have gained increasing attention from both the users and researchers. It is used in various fields which include environmental, healthcare, military and other commercial applications. Sensor nodes are battery powered so energy constraints on nodes are very strict. When battery gets discharged, sensor node will get disconnected from remaining network. This results in link failure and data loss. In some applications battery replacement is also not possible. Hence energy efficient techniques should be designed which will enhance lifetime of network and accurate data transfer. In this paper, different sources of energy dissipation are listed followed by energy efficient techniques to enhance lifetime of the network.

We have investigated the temperature and magnetic field dependence of magnetization, specific heat (Cp), and relative sample length change (ΔL/L0) for understanding the field-induced spin-structural change in quasi-one-dimensional spin chain α-CoV2O6 which undergoes antiferromagnetic (AFM) transition below TN = 15 K. Analysis of Cp(T) shows that an effective S = 1/2 Ising state is realized below 20 K, though the magnetic fluctuations persist well above TN. Cp and the coefficient of linear thermal expansion (α) exhibit strong H dependence in the AFM state. We also observe a huge positive magnetostriction [ΔL(H)/L0] below 20 K which does not show any tendency of saturation up to 9 T. With increasing field, a sharp and symmetric peak emerges below TN in both Cp(T) and α(T) due to field-induced first-order ferrimagnetic/ferromagnetic-paramagnetic transitions. The large value of magnetostriction below TN suggests strong spin–lattice coupling in α-CoV2O6.

We report the existence of a Griffiths-like phase over a wide range of x due to the formation of nanosize ferromagnetic clusters in La0.6Sr0.4Mn1–xCoxO3, the solid solution of ferromagnetic La0.6Sr0.4MnO3 and La0.6Sr0.4CoO3, from the magnetization measurements. In the studied compound, this phase arises due to the quenching of randomly distributed Co–O–Mn antiferromagnetic bonds in the ferromagnetic background. In contrary to the divalent alkaline-earth-doped manganites, the Griffiths-like phase in La0.6Sr0.4Mn1–xCoxO3 can exist entirely in the metallic state above TC (for x < 0.10). Based on the present study, a magnetoelectronic phase diagram is drawn.

The effect of high pressure (up to 8 GPa) on normal and superconducting state properties of PrFeAsO0.6F0.12, an 1111-type iron based superconductor close to optimal doped region, has been investigated by measuring the temperature dependence of resistivity. Initially, the superconducting transition temperature (T c) is observed to increase slowly by about 1 K as pressure (P) increases from 0 to 1.3 GPa. With further increase in pressure above 1.3 GPa, T c decreases at the rate of ~1.5 K/GPa. The normal-state resistivity decreases monotonically up to 8 GPa. We have also measured the pressure dependence of magnetization (M) on the same piece of PrFeAsO0.6F0.12 sample up to 1.1 GPa and observed T c as well as the size of the Meissner signal to increase with pressure in this low-pressure region. In contrast, for an over-doped PrFeAsO0.6F0.14 sample, magnetization measurements up to 1.06 GPa show that both T c and the Meissner signal decrease with pressure. The present study clearly reveals two distinct regions in the dome-shaped (T c-P) phase diagram of PrFeAsO0.6F0.12.

2H-TaSe2 has been one of unique transition metal dichalcogenides exhibiting several phase transitions due to a delicate balance among competing electronic ground states. An unusual metallic state at high-T is sequentially followed by an incommensurate charge density wave (ICDW) state at ≈122 K and a commensurate charge density wave (CCDW) state at ≈90 K, and superconductivity at TC ~ 0.14 K. Upon systematic intercalation of Pd ions into TaSe2, we find that CCDW order is destabilized more rapidly than ICDW to indicate a hidden quantum phase transition point at x ~ 0.09–0.10. Moreover, TC shows a dramatic enhancement up to 3.3 K at x = 0.08, ~24 times of TC in 2H-TaSe2, in proportional to the density of states N(EF). Investigations of upper critical fields Hc2 in single crystals reveal evidences of multiband superconductivity as temperature-dependent anisotropy factor γH = "Equation missing", quasi-linear increase of "Equation missing", and an upward, positive-curvature in "Equation missing" near TC. Furthermore, analysis of temperature-dependent electronic specific heat corroborates the presence of multiple superconducting gaps. Based on above findings and electronic phase diagram vs x, we propose that the increase of N(EF) and effective electron-phonon coupling in the vicinity of CDW quantum phase transition should be a key to the large enhancement of TC in PdxTaSe2.

We have investigated the magnetic and magnetocaloric properties of DyVO4 by magnetization and heat capacity measurements. χ ( T ) shows antiferromagnetic to paramagnetic transition at T N Dy ~ 3.5 K . The compound undergoes a metamagnetic transition and exhibits a huge entropy change. The maximum values of magnetic entropy change ( Δ S M ) , adiabatic temperature change ( Δ T ad ) and refrigerant capacity (RC) reach 26 J kg−1 K−1, 17 K, and 526 J kg−1, respectively for a field change of 0–8 T. Moreover, the material is highly insulating and exhibits no thermal and field hysteresis, satisfying the necessary conditions for a good magnetic refrigerant material.

In wireless ad-hoc network energy of node is very important issue. Less amount of energy is directly affect the lifetime of network because all nodes in networks are battery operated devices. So optimization of energy consumption in network has greater impact on network life. The power consumption can be reduced at node level, transmission and receiving level. This paper is focusing on how various propagation models affect the energy consumption in ad-hoc network with MANET routing protocols. The four widely used Ad-hoc routing protocols compared are: Ad-hoc on demand Distance Vector (AODV), Destination Sequenced Distance Vector (DSDV), Dynamic Source Routing (DSR), and Ad-hoc on demand Multipath Distance Vector (AOMDV). Simulation has been carried out using Network Simulator 2.34 and its associated tools like Network Animator.

VANET is Ad-hoc network it is V purpose of VANET is to reduce traffic on road, accident and also send some useful information VANET is dynamic topology hence routing the packet in efficient and effective manner is major challenge. In this paper we analyze DBR protocol with ROMSGP protocol for different parameters. Here we also apply power assignment which improves energy consumption, connectivity and throughput.

We have investigated the influence of 3d-4f spin interaction on magnetic and magnetocaloric properties of DyCrO$_4$ and HoCrO$_4$ compounds by magnetization and heat capacity measurements. Both the compounds exhibit complicated magnetic properties and huge magnetic entropy change around the ferromagnetic transition due to the strong competition between ferromagnetic and antiferromagnetic superexchange interactions. For a field change of 8 T, the maximum values of magnetic entropy change ($\Delta S_{M}^{max}$), adiabatic temperature change ($\Delta T_{ad}$), and refrigerant capacity (RC) reach 29 J kg$^{-1}$ K$^{-1}$, 8 K, and 583 J kg$^{-1}$, respectively for DyCrO$_4$ whereas the corresponding values for HoCrO$_4$ are 31 J kg$^{-1}$ K$^{-1}$, 12 K, and 622 J kg$^{-1}$. $\Delta S_{M}^{max}$, $\Delta T_{ad}$, and RC are also quite large for a moderate field change. The large values of magnetocaloric parameters suggest that the zircon-type DyCrO$_4$ and HoCrO$_4$ could be the potential magnetic refrigerant materials for liquefaction of hydrogen.

We have carried out Andreev reflection measurements on point contact junctions between normal metal and single crystals of the quasi-one-dimensional (Q1D) superconductor Nb2PdxSe5 (Tc ∼ 5.5 K). The contacts of the junctions were made on either self-cleaved surfaces or crystal edges so that the current flow directions in the two types of junctions are different, and the measurements provide a directional probe for the order parameter of the superconductor. Junctions made in both configurations show typical resistances of ∼20-30 Ohms, and a clear double-gap Andreev reflection feature was consistently observed at low temperatures. Quantitative analysis of the conductance spectrum based on a modified Blonder-Tinkham-Klapwijk (BTK) model suggests that the amplitudes of two order parameters may have angular dependence in the a-c plane. Moreover, the gap to transition temperature ratio (Δ/TC) for the larger gap is substantially higher than the BCS ratio expected for phonon-mediated s-wave superconductors. We argue that the anisotropic superconducting order parameter and the extremely large gap to transition temperature ratio may be associated with an unconventional pairing mechanism in the inorganic Q1D superconductor.

We have investigated the temperature dependence of the linear thermal expansion along the hexagonal c axis ($\Delta L$), in-plane resistivity ($\rho$), and specific heat ($C_p$) of the topological insulator Sb$_2$Te$_3$ single crystal. $\Delta L$ exhibits a clear anomaly in the temperature region 204-236 K. The coefficient of linear thermal expansion $\alpha$ decreases rapidly above 204 K, passes through a deep minimum at around 225 K and then increases abruptly in the region 225-236 K. $\alpha$ is negative in the interval 221-228 K. The temperature dependence of both $\alpha$ and $C_p$ can be described well by the Debye model from 2 to 290 K, excluding the region around the anomaly in $\alpha$.

We report the magnetic field dependence of resistivity ($\rho$) and specific heat ($C$) for the non-superconducting PrFeAsO compound. Our study shows a hitherto unobserved anomaly at $T_{SR}$ in the resistivity and specific heat data which arises as a result of the interplay of antiferromagnetic (AFM) Pr and Fe sublattices. Below the AFM transition temperature ($T_N^{\rm{Pr}}$), Pr moment orders along the crystallographic c axis and its effect on the iron subsystem causes a reorientation of the ordered inplane Fe moments in a direction out of the $ab$ plane. Application of magnetic field introduces disorder in the AFM Pr sublattice, which, in turn, reduces the out-of-plane Pr-Fe exchange interaction responsible for Fe spin reorientation. Both in $\rho$($T$) and $d(C/T)/dT$ curves, the peak at $T_{SR}$ broadens with the increase of $H$ due to the introduction of the disorder in the AFM Pr sublattice by magnetic field. In $\rho$($T$) curve, the peak shifts towards lower temperature with $H$ and disappears above 6 T while in $d(C/T)/dT$ curve the peak remains visible up to 14 T. The broadening of the anomaly at $T_N^{\rm{Pr}}$ in $C(T)$ with increasing $H$ further confirms that magnetic field induces disorder in the AFM Pr sublattice., Comment: 8 pages, 10 Figures

We report the observation of an unusual $B$ dependence of transverse magnetoresistance (MR) in the PrFeAsO, one of the parent compound of pnictide superconductors. Below the spin density wave transition, MR is large, positive and increases with decreasing temperature. At low temperatures, MR increases linearly with $B$ up to 14 T. For $T$$\geq$40 K, MR vs $B$ curve develops a weak curvature in the low-field region which indicates a crossover from $B$ linear to $B^2$ dependence as $B$$\rightarrow$0. The $B$ linear MR originates from the Dirac cone states and has been explained by the quantum mechanical model proposed by Abrikosov., Comment: accepted for publication in Appl. Phys. Lett

The magnetization of the PrFeAsO$_{0.60}$F$_{0.12}$ polycrystalline sample has been measured as functions of temperature and magnetic field $(H)$. The observed total magnetization is the sum of a superconducting irreversible magnetization ($M_s$) and a paramagnetic magnetization ($M_p$). Analysis of dc susceptibility $\chi(T)$ in the normal state shows that the paramagnetic component of magnetization comes from the Pr$^{+3}$ magnetic moments. The intragrain critical current density $(J_L)$ derived from the magnetization measurement is large. The $J_L(H)$ curve displays a second peak which shifts towards the high-field region with decreasing temperature. In the low-field region, a plateau up to a field $H^*$ followed by a power law $H^{-5/8}$ behavior of $J_L(H)$ is the characteristic of the strong pinning. A vortex phase diagram for the present superconductor has been obtained from the magnetization and resistivity data., Comment: A revised version with modified title,8 pages, 7 figures

We have measured the resistivity of PrFeAsO$_{1-x}$F$_y$ samples over a wide range of temperature in order to elucidate the role of electron-phonon interaction on normal- and superconducting-state properties. The linear T dependence of $\rho$ above 170 K followed by a saturationlike behavior at higher temperature is a clear signature of strong electron-phonon coupling. From the analysis of T dependence of $\rho$, we have estimated several normal-state parameters useful for understanding the origin of superconductivity in this system. Our results suggest that Fe-based oxypnictides are phonon mediated BCS superconductors like Chevrel phases and A15 compounds., Comment: 15 pages, 4 figures

We have synthesized oxygen-deficient fluorine-doped samples of nominal composition PrFeAsO$_{1-x}$F$_y$ to study the normal and superconducting state properties. Resistivity of undoped PrFeAsO exhibits a strong anomaly at around 155 K due to the spin-density-wave instability. Fluorine doping ($x$=0.4, $y$=0.12) suppresses this magnetic instability and drives the system to the superconducting ground state with superconducting onset temperature 50 K. The behavior of normal-state resistivity changes from $T^2$-like to $T$-linear to sublinear in $T$ with increasing temperature indicating that both electron-electron interaction and electron-phonon interaction are strong. From the analysis of $T$ dependence of $\rho$, we have estimated the electron-phonon coupling strength ($\lambda$) to be quite large (1.3)., Comment: 14pages,4 Figures

We have investigated the effect of applied pressure (P) on the magnetic and superconducting transitions of GdFeCoxAsO (x = 0, 0.1, 1) compounds by measuring the temperature dependence of resistivity. At ambient pressure, GdFeAsO undergoes a spin-density wave transition at associated with the 3d electrons of Fe. Under external pressure, TN decreases from 128.2 K at 0 GPa to 114.5 K at 2.5 GPa at the rate = 6 K/GPa. Unlike GdFeAsO, the isostructural GdCoAsO exhibits a ferrimagnetic ordering of the Co moments at 76 K which decreases from 76 K to 71 K as pressure increases from 0 to 2.5 GPa. For the GdFeCoAsO sample, the superconducting onset temperature Tcon decreases monotonically from 19 to 17.1 K, and the temperature Tczero at which the resistivity disappears decreases from 16.7 to 10.5 K as pressure increases from 0 to 2.9 GPa. For all the three samples, both the value of resistivity and the strength of electron–electron correlation decrease monotonically with increasing pressure.

We observe that the zircon-type RCrO4 (R = Ho, Gd, Lu) compounds exhibit complicated magnetic properties and large magnetic entropy change due to the strong competition between ferromagnetic and antiferromagnetic interactions. For a field change of 7 T, the maximum values of entropy change and refrigerant capacity reach 28 J kg−1 K−1 and 740 J kg−1, respectively, for GdCrO4 whereas the corresponding values for HoCrO4 are 29 J kg−1 K−1 and 550 J kg−1. For GdCrO4 compound, the magnetic entropy change is quite large even at low temperatures well below the ferromagnetic transition.

We have studied the vortex dynamics in the PrFeAsO$_{0.60}$F$_{0.12}$ superconducting sample by dc magnetization and dynamic magnetization-relaxation rate $(Q)$ measurements. The field dependence of the superconducting irreversible magnetization $M_s$ reveals a second magnetization peak or fishtail effect. The large value of $Q$ is an indication of moderate vortex motion and relatively weak pinning energy. Data analysis based on the generalized inversion scheme suggests that the vortex dynamics can be described by the collective pinning model. The temperature dependence of the critical current is consistent with the pinning due to the spatial variation in the mean free path near a lattice defect ($\delta l$ pinning). The temperature and field dependence of $Q$ indicates a crossover from elastic to plastic vortex creep with increasing temperature and magnetic field. Finally, we have constructed the vortex phase diagram based on the present data., Comment: 11 pages, 8 Figures, Accepted for publication in Journal of Applied Physics

We have investigated the magnetic and magnetocaloric properties of EuHo$_2$O$_4$ and EuDy$_2$O$_4$ by magnetization and heat capacity measurements down to 2 K. These compounds undergo a field-induced antiferromagnetic to ferromagnetic transition and exhibit a huge entropy change. For a field change of 0-8 T, the maximum magnetic entropy and adiabatic temperature changes are 30 (25) J kg$^{-1}$ K$^{-1}$ and 12.7 (16) K, respectively and the corresponding value of refrigerant capacity is 540 (415) J kg$^{-1}$ for EuHo$_2$O$_4$ (EuDy$_2$O$_4$). These magnetocaloric parameters also remain large down to lowest temperature measured and are even larger than that for some of the potential magnetic refrigerants reported in the same temperature range for a moderate field change. Moreover, these materials are highly insulating and exhibit no thermal and field hysteresis, fulfilling the necessary conditions for a good magnetic refrigerant in the low-temperature region.

We have measured the temperature and magnetic field dependence of resistivity of polycrystalline PrFeAsO0.60F0.12 samples in the normal and superconducting state. The superconducting onset transition temperature Tcon shifts by ~4 K as H is increased from 0 to 14 T. The zero-temperature upper critical field Hc2(0) estimated by using the Ginzburg–Landau theory and the Werthamer–Helfand–Hohenberg equation exceeds 100 T. The resistivity below Tcon exhibits Arrhenius behavior due to thermally activated flux flow of vortices. The activation energy U0, determined from the Arrhenius plot of the resistivity, shows a power-law decrease () with magnetic field. The normal-state magnetoresistance varies quasilinearly with magnetic field and does not obey Kohler's rule, suggesting a multiband feature of the material.