Current-voltage characteristics in single layer SrIrO3films deposited on LaAlO3(100) substrate.

Here, we investigate the structural and electrical properties on SrIrO3films grown on LaAlO3(100) substrate with varying thickness (18, 25 and 40 nm). The x-ray diffraction shows good quality epitaxial films without any chemical impurity. The out-of-plane lattice parameter increases with the film thickness. All the films show a semiconducting behavior where the resistivity increases with increasing thickness. Our analysis shows at high temperature the charge conduction mechanism follows Mott's two-dimensional variable-range-hopping model. Detailed current-voltage (I-V) measurements show a linear Ohmic behavior at room temperature, however, a prominent deviation from linearity has been observed at low temperatures where the exponentn(I∝Vn) increases with decreasing temperature, reachingn ∼1.5 at low temperature. Analysis ofI-Vdata indicates that the charge conduction has dominant contribution of Poole-Frenkel mechanism rather than Schottky behavior. This evolution of charge transport with temperature is quite intriguing which may be related to the development of low temperature magnetism in films of SrIrO3.

Coexistence of spin liquid state and magnetic correlations in 3d-5dbased triangular-lattice antiferromagnet Sr3CuIr2O9.

Here, we report detailed lattice structure, magnetization (dc and ac) and specific heat measurements on a 3d-5dbased new triple-perovskite material Sr3CuIr2O9. The Sr/Cu forms a layered structure of triangular-lattice while the Ir forms Ir2O9dimers which lie in chain as well as simultaneously makes layered triangular-lattice with neighboring atoms. Due to random site-sharing with Sr2+, the Cu2+(3d9, spin-1/2) forms a diluted magnetic lattice, thus giving a disordered in-plane exchange interaction. Opposed to conventionalJeffmodel, the Ir5+(5d4,Jeff= 0) is believed to be magnetic here which participates both in-chain and in-plane magnetic interactions. This complex lattice structure driven competing exchange interaction leads the ground state to a gapless quantum-spin-liquid state which coexists with (weak) ferromagnetic spin correlations. While underling the importance of spin state (spin-1/2), we believe that the combined effect of lattice structure, geometric frustration, spin-orbit coupling and spin state has given rise this interesting ground state in this material.

Temperature dependent89Y NMR study on multiferroic YCrO3.

In this manuscript, we report the89Y NMR measurement as a function of temperature on single phase and pure polycrystalline YCrO3sample to study the magnetism and relaxation times on a microscopic level across the magnetic transition (TN≃ 141 K) from paramagnetic to antiferromagnetic state. The NMR peak width broadens abruptly upon crossingTNdue to the onset of internal magnetic fields, while peakshift slight decreases. A slight increase and subsequent anomalous decrease in the NMR peak intensity is observed on approachingTNfrom 300 K. There is also a significant increase in peak width. The temperature dependence of the89Y NMR spin-lattice relaxation rates 1/T1indicates a phase transition atTNwhich is of magnetic origin due to Cr3+ions, with an anomalously rise of fluctuations belowTN. AboveTN, this spin-lattice relaxation rate can be fitted to a power-law scaling behavior 1/T1∼Tßwith an exponent factorß≈ 0.8, indicates low energy spin fluctuations. Moreover, Knight shift and 1/TT1scales linear with the bulk susceptibility which suggests the antiferromagnetic spin fluctuation in the YCrO3system.

Methods and variables in Electrical discharge machining of titanium alloy - A review.

Titanium alloys are difficult to machine using conventional methods, therefore, nonconventional processes are often chosen in many applications. Electrical discharge machining (EDM) is one of those nonconventional processes that is used frequently for shaping titanium alloys with their respective pros and cons. However, a good understanding of this process is very difficult to achieve as research results are not properly connected and presented. Therefore, this study investigates different types of EDM processes such as, wire EDM, die-sink EDM, EDM drill and hybrid EDM used to machine titanium alloys. Machining mechanism, tool electrode, dielectric, materials removal rate (MRR), and surface integrity of all these processes are critically analysed and correlated based on the evidence accessible in literature. Machining process suffer from lower material removal rate and high tool wear while applied on titanium alloys. Formation of recast layer, heat affected zone and tool wear is common in all types of EDM processes. Additional challenge in wire EDM of titanium alloys is wire breakage under severe machining conditions. The formation of TiC and TiO2 are noticed in recast layer depending on the type of dielectrics. Removal of debris from small holes during EDM drilling is a challenge. All these restricts the applications EDMed titanium alloys in high-tech applications such as, aerospace and biomedical areas. Most of these challenges come up due to extraordinary properties such as, low thermal conductivity, high melting point and high hardness, of titanium alloys. Though hybrid EDM has been introduced and there is some work on simulation of EDM process, further developments in EDM of this alloy is required for widening the application of this methods.

Structural, magnetic and dielectric properties in 3d-5dbased Sr2FeIrO6thin films.

The structural, magnetic and dielectric properties have been investigated in 3d-5dbased double perovskite Sr2FeIrO6thin films deposited by pulse laser deposition technique. To understand the effect of strain, epitaxial films are grown with varying thickness as well as on different substrates i.e., SrTiO3(100) and LaAlO3(100). The films with highest thickness are found to be more relaxed. Atomic force microscope images indicate all films are of good quality where grain sizes increase with increase in film thickness. X-ray absorption (XAS) spectroscopy measurements indicate a Ir5+charge state in present films while providing a detailed picture of hybridization between Fe/Ir-dand O-porbitals. The bulk antiferromagnetic transition is retained in films though the transition temperature shifts to higher temperature. Both dielectric constant (ϵr) and loss (tan δ) show change around the magnetic ordering temperatures of bulk Sr2FeIrO6indicating a close relation between dielectric and magnetic behaviors. A Maxwell-Wagner type relaxation is found to follow over whole frequency range down to low temperature in present film. On changing the substrate i.e., LaAlO3(100), theϵr(T) and (tan δ(T)) show almost similar behavior butϵrshows a higher value which is due to an increased strain coming from high mismatch of lattice parameters.

Electronic properties in itinerant ferromagnet SrRu1-x Ti x O3.

Here, we study the electrical transport and specific heat in 4d based ferromagnetic material SrRuO3 and its Ti substituted SrRu1-x Ti x O3 series (x ⩽ 0.7). The SrRuO3 is a metal and shows itinerant ferromagnetism with transition temperature T c ∼ 160 K. The nonmagnetic Ti4+ (3d 0) substitution would not only weaken the active Ru-O-Ru channel but is also expected to tune the electronic density and electron correlation effect. A metal to insulator transition has been observed around x ∼ 0.4. The nature of charge transport in paramagnetic-metallic state (x ⩽ 0.4) and in insulating state (x > 0.4) follows modified Mott's variable range hopping model. In ferromagnetic-metallic state, resistivity shows a T 2 dependence below T c which though modifies to T 3/2 dependence at low temperature. In Ti substituted samples, temperature range for T 3/2 dependence extends to higher temperature. Interestingly, this T 3/2 dependence dominates in whole ferromagnetic regime in presence of magnetic field. This evolution of electronic transport behavior can be explained within the framework of Fermi liquid theory and electron-magnon scattering mechanism. The negative magnetoresistance exhibits a hysteresis and a crossover between negative and positive value with magnetic field which is connected with magnetic behavior in series. The decreasing electronic coefficient of specific heat with x supports the increasing insulating behavior in present series. We calculate a high Kadowaki-Woods ratio (x ⩽ 0.3) for SrRuO3 which increases with substitution concentration. This signifies an increasing electronic correlation effect with substitution concentration.

Site dilution and charge disorder effect on physical properties in SrRu1-x Ga x O3.

Here, we report an evolution of structural, magnetic and transport behavior in doped SrRu1-x Ga x O3 (x [Formula: see text] 0.2). The nonmagnetic dopant Ga3+ (3d 10) not only acts for magnetic site dilution in SrRuO3 but also modifies the Ru charge state and electronic density. Our studies show that Ga3+ substitution does not affect the original orthorhombic- Pbnm structure of SrRuO3 which is due to its matching ionic radii with Ru4+ . However, Ga3+ has a substantial effect on the magnetic behavior of SrRuO3 where it decreases both magnetic moment as well as magnetic transition temperature [Formula: see text]. Further, this dilution induces Griffiths phase behavior across [Formula: see text] and cluster-glass behavior at low temperature with higher concentration of doping. The magnetic critical exponent [Formula: see text] increases with x due to this site dilution effect. The Ga3+ induces an insulating state in SrRuO3 with x > 0.05. The charge transport in paramagnetic as well as in insulating state of samples can be well described with Mott's modified variable-range-hopping model. The metallic charge transport just below [Formula: see text] in SrRuO3 obeys Fermi liquid behavior which breaks down at low temperature. We further find a correlation between field dependent magnetoresistance and magnetization through power-law behavior over the series.

Understanding the wire electrical discharge machining of Ti6Al4V alloy.

Non-conventional machining process for instance, wire electrical discharge machining (WEDM) of titanium alloys is gaining attention due to non-contact nature of this process. To deepen the understanding in this area, this study investigates surface generation, kerf width, discharge gap, material removal rate and wire degradation during WEDM of Ti6Al4V alloy. Pulse on time (4-10 µs), flushing pressure (7-18 MPa) and wire tension (800-1700 gf) were varied and resulting influences on output parameters were analysed. It was found that, machined surfaces consist of multi-layered recast layer with the presence of cracks, holes as well as traces of materials from electrode wire. The composition and roughness of the machined surface varies slightly with respect to machining condition without following any trend. In addition, deformation and morphology of deformed wire electrode after the WEDM process was also reported in this study.

Unusual exchange bias in Sr2FeIrO6/La0.67Sr0.33MnO3 multilayer.

Here, we study interface induced magnetic properties in a 3d-5d based multilayer made of La0.67Sr0.33MnO3 and double perovskite Sr2FeIrO6, respectively. Bulk La0.67Sr0.33MnO3 is metallic and shows ferromagnetic (FM) ordering above room temperature. In contrast, bulk Sr2FeIrO6, is an antiferromagnet (AFM) with a Néel temperature around 45 K ([Formula: see text]) and exhibits an insulating behavior. Two set of multilayers have been grown on SrTiO3 (1 0 0) crystal with varying thickness of FM layer. A multilayer with equal thickness of La0.67Sr0.33MnO3 and Sr2FeIrO6 (∼10 nm) shows exchange bias (EB) effect both in conventionally field cooled (FC) as well as in zero field cooled (ZFC) magnetic hysteresis measurements which is rather unusual. The ZFC EB effect is weakened both with increasing maximum field during initial magnetization process at low temperature and with increasing temperature. Interestingly, a multilayer with reduced thickness of La0.67Sr0.33MnO3 (∼5 nm) does not exhibit ZFC EB phenomenon, however, the FC EB effect is strengthened showing much higher value. We believe that an AFM type exchange coupling at the interface and its evolution during initial application of magnetic field causes this unusual EB in present multilayers.

Solvatochromism in highly luminescent environmental friendly carbon quantum dots for sensing applications: Conversion of bio-waste into bio-asset.

Recently studies on synthesis and fluorescence based sensing in biocompatible carbon quantum dots (CQDs) have become a widely spoken topic of research due to the several advantageous properties of CQDs in compared to semiconductor quantum dots. In this work, we have reported the rarely reported solvatochromism along-with a high photoluminescence (PL) quantum yield (PLQY) of 22%. Samples have been synthesized by using a simple process of hydrothermal carbonization of a naturally occurring bio-waste i.e. Aegle marmelos leaves powder. The linear absorption and PL emission characteristics of CQDs have been studied in different solvent environments to explore the origin of the observed excitation dependent PL emissions characteristics of the sample. The interesting solvatochromic PL (SPL) behavior of CQDs are observed at an excitation wavelength of 325nm by dispersing them in different polar protic and aprotic solvents, which suggest their possible applications as a replacement of solvatochromic dye molecules for sensing applications. Different polarity functions and molecular-microscopic solvent polarity parameter (ETN) are used to calculate the change in dipole moment (Δδ) of the solute-solvent system and the origin of SPL in CQDs has been explained. The SPL behavior of CQDs has been utilized for fluorescence sensing of organic liquids (Ethanol and Tetrahydrofuran) in water. Whereas, the photo-induced electron transfer mediated quenching in PL of aqueous dispersion of CQDs has led to development of "turn off" fluorescence Fe3+ ion sensor with a detection limit of 0.12µM. Therefore, this work may open a new avenue of conversion of a bio-waste into a fluorescent bio-asset.

Structure, magnetism and electronic properties in 3d-5d based double perovskite ([Formula: see text]Y x )2FeIrO6.

The 3d-5d based double perovskites are of current interest as they provide model systems to study the interplay between electronic correlation (U) and spin-orbit coupling (SOC). Here, we report detailed structural, magnetic and transport properties of doped double perovskite material ([Formula: see text]Y x )2FeIrO6 with [Formula: see text]. With substitution of Y, the system retains its original crystal structure but structural parameters change with x in nonmonotonic fashion. The magnetization data for Sr2FeIrO6 show antiferromagnetic type magnetic transition around 45 K; however, a close inspection of the data indicates a weak magnetic phase transition around 120 K. No change of structural symmetry has been observed down to low temperature, although the lattice parameters show sudden changes around the magnetic transitions. Sr2FeIrO6 shows an insulating behavior over the whole temperature range, which nevertheless does not change with Y substitution. The nature of charge conduction is found to follow thermally activated Mott's variable range hopping and power law behavior for parent and doped samples, respectively. Interestingly, evolution of structural, magnetic and transport behavior in ([Formula: see text]Y x )2FeIrO6 is observed to reverse with [Formula: see text], which is believed to arise due to a change in the transition metal ionic state.

Site dilution in SrRuO3: effects on structural and magnetic properties.

We have investigated the effect of site dilution with substitution of nonmagnetic element in SrRu1-x Ti x O3 (x ⩽ 0.7). The nature of ferromagnetic state in SrRuO3 is believed to be of itinerant type with transition temperature [Formula: see text] K. Crystallographically, SrRuO3 has a distorted orthorhombic structure. Substitution of [Formula: see text] (3d 0) for Ru+4 (4d 4), however, does not introduce significant structural modification due to their matching ionic radii. This substitution, on the other hand, is expected to tune the electronic correlation effect and the d electron density in the system. With Ti substitution, we find that magnetic moment and Curie temperature decreases but T c remains unchanged which has been attributed to opposite tuning of electron correlation effect and density of states within the framework of itinerant ferromagnetism. The estimated critical exponent (ß) related to magnetization implies a mean-field type of magnetic nature in SrRuO3. The value of ß further increases with x which is understood from the dilution effect of magnetic lattice. The system evolves to exhibit Griffiths phase like behavior above T c which is usually realized in diluted ferromagnet following local moment model of magnetism. Our detail analysis of magnetization data indicates that magnetic state in SrRuO3 has contribution from both itinerant and local moment model of magnetism.

Finite-size effect on evolution of Griffiths phase in manganite nanoparticles.

The finite-size effect on the evolution of the Griffiths phase (GP) is studied using nanoparticles of half-doped manganite Pr0.5Sr0.5MnO3 with different average particle sizes but with similar structural parameters. All the samples exhibit pronounced GP behavior. With reducing the particle size, the Griffiths temperature remains almost unchanged but the characteristic critical temperature [Formula: see text] decreases and the GP properties are strengthened. It is noteworthy that the shift of [Formula: see text] follows finite-size scaling with the particle size revealing an exotic interplay between the GP properties and the sample dimension. This reinforces an earlier proposal of length-scale related evolution of GP.

A Novel Technique of Synthesis of Highly Fluorescent Carbon Nanoparticles from Broth Constituent and In-vivo Bioimaging of C. elegans.

Here we have demonstrated a novel single step technique of synthesis of highly fluorescent carbon nanoparticles (CNPs) from broth constituent and in vivo bioimaging of Caenorhabditis elegans (C. elegans) with the synthesized CNPs has been presented. The synthesized CNPs has been characterized by the UV-visible (UV-Vis) absorption spectroscopy, transmission electron microscopy (TEM) and Raman studies. The sp (2) cluster size of the synthesized samples has been determined from the measured Raman spectra by fitting it with the theoretical skew Lorentzian (Breit-Wigner- Fano (BWF)) line shape. The synthesised materials are showing excitation wavelength dependent tunable photoluminescence (PL) emission characteristics with a high quantum yield (QY) of 3 % at a very low concentration of CNPs. A remarkable increase in the intensity of PL emission from 16 % to 39 % in C. elegans has also been observed when the feeding concentration of CNPs to C. elegans is increased from 0.025 % to 0.1 % (w/v). The non-toxicity and water solubility of the synthesized material makes it ideal candidate for bioimaging.

Detection and characterization of zoonotic dermatophytes from dogs and cats in and around Kolkata.

AIM: The ringworms of pet dogs, cats, and stray animals (dogs, cats, and other animals) could be a potential source of zoonotic infections causing a serious public health problem in the busy city Kolkata. The pet owners are more susceptible to get this infection from their pets, because of the close contact with them as dermatophytosis is very much prevalent in those pets. So, this study was aimed to check the prevalence of dermatophytosis in dogs, cats, and in pet owners. MATERIALS AND METHODS: A total of 362 clinically suspected cases of dermatophytosis from dogs (123 in number), cats (202 in number), and human beings (37 in number) were collected and studied from in and around Kolkata to detect the presence of significant dermatophytes. Direct microscopy and cultural examination of the isolates were performed following standard methodology. Identification and characterization of the isolates were done by different biochemical tests. RESULTS: Samples (n=285) having significant dermatophytic fungal infections were found to be of highest number in cats (158, 55.5%) than in dogs (108, 37.8%) and humans (19, 6.7%), respectively. The incidence of Microsporum canis (60.0%) was the highest from affecting dogs, cats, and human beings in comparison to Microsporum gypseum (22.5%), Trichophyton mentagrophytes (15.8%) and Trichophyton rubrum (1.7%). Detection of T. rubrum was only from human cases in this study, whereas the presence of rest three were slightly higher in cats than that of the dogs and humans in this present study. The incidences were higher in young animals and in humans of the age group of 21-30 years, during the rainy season (from April to August) and also in in-contact human beings. CONCLUSION: M. canis was the most commonly pathogen among all causing dermatophytosis in animals and also in the pet owners. M. gypseum and T. mentagrophytes were other pathogens associated with these infections. These infections were more prevalent in the rainy seasons and in in-contact human patients or pet owners.

Temperature evolution of magnetic and transport behavior in 5d Mott insulator Sr2IrO4: significance of magneto-structural coupling.

We have investigated the temperature evolution of magnetism and its interrelation with structural parameters in the perovskite-based layered compound Sr2IrO4, which is believed to be a J(eff) = 1/2 Mott insulator. The structural distortion plays an important role in this material and induces a weak ferromagnetism in an otherwise antiferromagnetically ordered magnetic state with a transition temperature around 240 K. Interestingly, at low temperatures, below around 100 K, a change in the magnetic moment has been observed. Temperature dependent x-ray diffraction measurements show that sudden changes in structural parameters around 100 K are responsible for this. Resistivity measurements show insulating behavior throughout the temperature range across the magnetic phase transition. The electronic transport can be described with Mott's two-dimensional variable range hopping (VRH) mechanism, however, three different temperature ranges are found for VRH, which is a result of varying the localization length with temperature. A negative magnetoresistance (MR) has been observed at all temperatures in contrast to positive behavior generally observed in strongly spin-orbit coupled materials. The quadratic field dependence of MR implies the relevance of a quantum interference effect.

A novel technique in airway management of neonates with occipital encephalocele.

Airway stabilization in neonates with occipital encephalocele (OE) is critical during surgery or if they develop hypoxic-respiratory failure. Endotracheal intubation can be challenging due to difficulty in positioning the head in a patient with large occipital mass. We describe a novel technique for positioning neonates with large OE using a commonly used hospital apparatus which facilitated appropriate positioning of the baby and successful endotracheal intubation with ease and no additional staff.

Hemimelia and absence of the peroneal artery.

The arterial patterns of the lower extremities of three patients with congenital absence fibulae (hemimelia) were evaluated to determine whether the relationship existed between the absence of peroneal artery and hemimelia. Computerized tomograph angiography revealed the absence of peroneal artery in all the patients with dysplastic limbs and absent fibula.

Flux dynamics and avalanches in the 122 pnictide superconductor Ba0.65Na0.35Fe2As2.

In this work we present the results of the bulk magnetization measurements in a superconducting state of single crystals of Ba0.65Na0.35Fe2As2. The isothermal magnetic field (H âˆ¥ c axis) dependent magnetization (M) loops exhibit a second peak (SP) or 'fishtail effect', as well as remarkable flux jumps at low temperatures. The critical current density Jc obtained from the M(H) loops is rather high, of the order of 10(6) A cm(-2). The analysis of the temperature- and field-dependent Jc implies that high Jc is mainly due to collective (weak) pinning of vortices by dense microscopic point defects with some contribution from a strong pinning mechanism. Pronounced magnetic instabilities in terms of flux jumps depend strongly on temperature as well as on the field sweep rate. The field for the first flux jump as calculated from an adiabatic model, however, is much lower than the experimentally observed values, and this enhanced stability is attributed to a flux creep phenomenon. The analysis of field-dependent magnetic relaxation data additionally supports a collective pinning model. The data further suggest that SP in M(H) is likely related to the crossover in creep dynamics from an elastic to a plastic mechanism. We have constructed the vortex phase diagram on the field-temperature plane.

WERF Nutrient Challenge investigates limits of nutrient removal technologies.

The WERF Nutrient Challenge is a multi-year collaborative research initiative established in 2007 to develop and provide current information about wastewater treatment nutrients (specifically nitrogen and phosphorus in wastewater), their characteristics, and bioavailability in aquatic environments to help regulators make informed decisions. The Nutrient Challenge will also provide data on nutrient removal so that treatment facilities can select sustainable, cost-effective methods and technologies to meet permit limits. To meet these goals, the Nutrient Challenge has teamed with a wide array of utilities, agencies, consultants, universities and other researchers and practitioners to collaborate on projects that advance these goals. The Nutrient Challenge is focusing on a different approach to collaborating and leveraging resources (financial and intellectual) on research projects by targeting existing projects and research that correspond with its goals and funding those aspects that the Nutrient Challenge identified as a priority. Because the Nutrient Challenge is focused on collaboration, outreach is an absolutely necessary component of its effectiveness. Through workshops, webinars, a web portal and online compendium, published papers, and conference lectures, the Nutrient Challenge is both presenting important new information, and soliciting new partnerships.