High gas pressure and high-temperature synthesis (HP-HTS) technique and its impact on iron-based superconductors

The high-pressure growth technique generally plays an important role in the improvement of the sample quality and the enhancement of various physical and magnetic properties of materials. The high gas pressure technique provides a large sample space (10-15 cm) to grow various kinds of materials. In this paper, we introduce the high gas pressure and high-temperature synthesis (HP-HTS) technique that is present at our institute and is applied to the growth process of different kinds of superconducting materials, particularly iron-based superconductors. More details and the working principle of this HP-HTS technique are discussed. We have also demonstrated the current results based on the iron-based superconductors by using this unique HP-HTS technique. These results demonstrate the enhancement of the superconducting properties with the improved sample quality compared to the conventional synthesis process at ambient pressure.Comment: 12 pages, 8 figure

ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF TABERNAEMONTANA HEYNEANA WALL. AN ENDEMIC PLANT OF WESTERN GHATS

Objective: The aim of this study was to investigate the antioxidant and antimicrobial properties of different crude extracts of leaves of T. heyneanaMethods: Crude extracts of methanol, chloroform, dichloromethane and dichloroethane of leaf were evaluated for antimicrobial activity by disc diffusion method and antioxidant activity by DPPH (diphenyl-2-picrylhydrazyl) and reducing power assay. Quantitative analysis of total phenolics was done by Folin-Ciocalteau method and total flavonoids by aluminium chloride method.Results: Methanolic extract of T. heyneana exhibited the presence of all the phytochemicals tested except triterpenoids and saponins. The highest phenolic content of 14.0±0.45 mg GAE/g and flavonoid content of 81.62±0.47 mg QE/g were found in methanol extract. The highest DPPH scavenging activity (IC50 20.3±0.56 µg/ml) and reducing power was exhibited by methanolic extract. The methanolic extract showed maximum antibacterial activity of 12.66±0.57 mm zone of inhibition against Staphylococcus aureus and least of 9.23±0.25 mm against Proteus vulgaris.Conclusion: These findings provide scientific evidence to support the traditional use of Tabernaemontana heyneana Wall. and also indicate that the leaves of this species are a promising potential for the development of antioxidant and antimicrobial agents

Enhancement of Superconducting Properties of Polycrystalline CaKFe4As4 by High-Pressure Growth

High-pressure growth is a unique method to improve the sample quality and size. Here, we have used the high gas pressure and high-temperature synthesis (HP-HTS) method to grow CaKFe4As4 (1144) bulks and investigated their superconducting properties using structural, microstructural, transport, and magnetic studies. The microstructural analysis demonstrates that 1144 samples prepared by HP-HTS have improved the sample density and grain connectivity. The transition temperature (Tconset) of 1144 bulks prepared by HP-HTS is increased up to 35.2 K with a transition width ({\Delta}T) of 1 K, which is remarkably comparable to the reported 1144 single crystal. Additionally, the critical current density (Jc) is enhanced by almost one order of magnitude compared with the parent compound prepared by the conventional synthesis process at ambient pressure (CSP), which could be attributed to the improved sample density and effective pinning centers. Our study demonstrates that the sample quality and superconducting properties of various iron-based superconductors can be enhanced by applying the HP-HTS approach, and further research is demanded in this direction.Comment: 17 pages, 7 figure

Optimization of Synthesis Parameters and Superconducting Properties of GdFeAsO1-xFx

REFeAsO (RE1111; RE: rare earth) belongs to the 1111 family of iron-based superconductors (FBS), which illustrates the enhancement of the superconducting transition (Tc) with smaller radii of RE. However, the synthesis of the 1111 phase with a heavy rare-earth is always challenging. In this paper, we report the optimization of the growth and superconducting properties of F-doped GdFeAsO1-xFx bulks by preparing the samples in a wide temperature range (700-1100{\deg}C) at ambient pressure. The optimized synthesis parameters are concluded based on structural, microstructural, transport, and magnetic measurements. These findings suggest that the optimal conditions for preparing F-doped Gd1111 bulks involve a two-step process at 900{\deg}C for 61 hours at ambient pressure, which is lower than previously reported. The optimized samples have revealed the superconducting transition temperature (Tconset) of 43 K for GdFeAsO0.83F0.17. The first-time reported critical current Jc value for this Gd1111 is observed of the order of 10^3 (A/cm^2) at 0 T and 5 K. Our investigation also concluded that highly pure precursors, particularly gadolinium metal, are required to achieve the superconducting properties of F-doped Gd1111. A high growth pressure of 1 GPa reduces the superconducting properties of F-doped Gd1111

Antimony Doping Effect on the Superconducting Properties of SmFeAs(O,F)

We report the synthesis and characterization of a series of antimony-doped SmFeAs1-xSbxO0.8F0.2 (x = 0, 0.01, 0.03, 0.05, 0.1, 0.2, and 0.3) bulks to investigate the twin doping effects on the superconducting properties of SmFeAs(O,F) caused by fluorine (F) incorporation at O-site in SmO layer and antimony (Sb) substitution at As-site in the conducting layer (FeAs). Since the antimony (Sb) has a larger size than arsenic (As), the enhancement of lattice parameters has been confirmed by the XRD analysis. Microstructural analysis confirms that Sb-doping leads to a small improvement in the sample density and an increase in the inhomogeneity of the constituent elements, especially at higher Sb-doping levels. The parent compound SmFeAsO0.8F0.2 has shown the superconducting transition (Tc) at ~54 K, which is systematically reduced with the antimony doping contents (x). Our investigation indicates that the Sb-doped SmFeAs(O,F) phase at low levels is less prone to the multiphase formation than at high levels, which affects the inter- and intragranular behaviour originating from the microstructure nature of 1111 bulks. The critical current density (Jc) of the parent compound has almost the same value as previously reported, which is suppressed slowly with increased Sb-doping. It could be due to the reduced grain connections and the effective pinning centers. This study confirms that the superconducting FeAs layer doping with larger ions at arsenic sites does not support the superconducting properties of Sm1111, which is a distinct behavior from that of Sb-doped CeFeAs(O,F) and LaFeAs(O,F).Comment: 18 pages, 8 figure

High-pressure synthesis and the enhancement of the superconducting properties of FeSe0.5Te0.5

A series of FeSe0.5Te0.5 bulk samples have been prepared through the high gas pressure and high-temperature synthesis (HP-HTS) method to optimize the growth conditions, for the first time and investigated for their superconducting properties using structural, microstructure, transport, and magnetic measurements to reach the final conclusions. Ex-situ and in-situ processes are used to prepare bulk samples under a range of growth pressures using Ta-tube and without Tatube. The parent compound synthesized by convenient synthesis method at ambient pressure (CSP) exhibits a superconducting transition temperature of 14.8 K. Our data demonstrate that the prepared FeSe0.5Te0.5 sealed in a Ta-tube is of better quality than the samples without a Ta-tube, and the optimum growth conditions (500 MPa, 600{\deg}C for 1 h) are favourable for the development of the tetragonal FeSe0.5Te0.5 phase. The optimum bulk FeSe0.5Te0.5 depicts a higher transition temperature of 17.3 K and a high critical current density of the order of >10^4 A/cm^2 at 0 T, which is improved over the entire magnetic field range and almost twice higher than the parent compound prepared through CSP. Our studies confirm that the high-pressure synthesis method is a highly efficient way to improve the superconducting transition, grain connectivity, sample density, and also pinning properties of a superconductor

Comparison of Gd addition effect on the superconducting properties of FeSe0.5Te0.5 bulks under ambient and high-pressure conditions

We have prepared a series of (FeSe0.5Te0.5 + xGd) bulk samples, with x = 0, 0.03, 0.05, 0.07, 0.1 and 0.2, through the convenient solid-state reaction method at ambient pressure (CSP). High gas pressure and high-temperature synthesis methods (HP-HTS) are also applied to grow the parent compound (x = 0) and 5-wt% of Gd-added bulks. Structural, microstructural, transport and magnetic characterizations have been performed on these samples in order to draw the final conclusion. Our analysis results that the HP-HTS applied for the parent compound enhances the transition temperature (Tc) and the critical current density (Jc) with the improved sample density and intergrain connections. The lattice parameter c is increased with Gd additions, suggesting a small amount of Gd enters the tetragonal lattice of FeSe0.5Te0.5 and the Gd interstitial sites are along the c-axis. A systematic decrease of the onset transition temperature Tc is observed with Gd additions, however, the calculated Jc of these Gd-added samples is almost the same as that of the parent compound prepared by CSP. It specifies that there is no improvement of the grain connections or pinning properties due to these rare earth additions. However, Gd-added FeSe0.5Te0.5 bulks prepared by HP-HTS have revealed a slightly improved critical current density due to improved grain connections and sample density but have a lower transition temperature than that of the parent compounds.Comment: 33 pages, 9 figures, 3 table

PLANT DYNAMICS: Triticum Infection Disclosure

Agriculture being the pillar of the economy for a developing country like India has a vital role in the survival of living beings on earth. Wheat is the most widely consumed grain on the planet. Deep learning is an evolving technology that is having a significant effect in the field of agriculture, assisting farmers in modernizing their operations. One such application is the identification of plant diseases using image classification which is necessary for long-term agriculture sustainability. Wheat plants are susceptible to a variety of fungal diseases. Hence early identification of diseases of crops like wheat and rice that are staple food of people in many countries is critical. Using deep learning algorithms such as CNN, this proposed system aims to predict wheat diseases. We are introducing a deep learning-based model for image classification to predict wheat diseases. Previous approaches used machine learning algorithms for a general dataset that included all types of crop diseases. To achieve better precision, we built our own dataset and combined it with existing similar datasets to account for 4 major classes of wheat diseases. The dataset consists of 700 images of wheat plants. Based on the input, our system determines if the plant is healthy or diseased so that precautionary measures can be taken to prevent losses in wheat cultivation, which could lead to food shortage

Design and Implementation of Modified Zeta Converter for Solar Water Pumping Application

The linear increase in the growth of the population demands a requisite for energy resources. Knowing the loathsome truth that non-renewable sources will ultimately exhaust, the significance of renewable sources cannot be undervalued. Considering various factors, many work areas are reliant upon fossil fuels for the generation of electricity. The use of fossil fuels will increase the quality of power production but will drain one day, and industries must change to renewable sources. The earliest system that strikes a chord with regard to renewable energy is the photovoltaic (PV) energy system. In this specific circumstance, interest in solar systems is expanding step by step, and its installations are becoming broad. The implementation of the solar water pumping method used for irrigation purposes using a Zeta converter was best suited for small and minor farmers, but still, the efficiency of the system can be upgraded with the use of filters. The vantage of the ZETA converter has less result voltage ripple and smooth water pumping application. The PV-based system has reached the point where it is used in Electric vehicles by enhancing the standard operating condition of the converter under the steady and dynamic behavior of a PV system. Eventually, it can be worked considerably under minimum solar irradiance. Maximum power point tracking (MPPT) of the signal had dominant performance in a zeta converter circuit while sign levels ripple current, and voltage on the output side was compact