Magnetoelectric Effect in Lead-Free Multiferroic Composites and Thin Films

The functional behavior of two-phase composites consisting of piezoelectric and magnetostrictive components is a manifestation of the coupled nature of their constituent phases, known as magnetoelectric (ME) effect. It has a promise in it to a progress in the modern electronic industry by not only improving the existing properties but also reducing the size of microelectronic components. However, the demand for miniaturization has not seized because it is now accompanied by the demand of environment-friendly materials. Therefore, the primary aims of this dissertation are to develop new lead-free multiferroic materials and to study the relationship between the intrinsic properties of piezoelectric and magnetostrictive components and the resulting ME coupling between them. The ferroelectric component with excellent piezoelectric properties combined with the component with excellent magnetostrictive properties would lead to enhanced ME coupling and value-added understanding of the science behind it. At first, a piezoelectric composition in the system of (1-x)(Ba,Ca)TiO3 -xBa(Zr,Ti)O3 with x = 0.5 was identified (BCT50-BZT) with piezoelectric coefficient of value greater than 500 pC/N in order to utilize it as the piezoelectric phase. The converse ME coefficient of 0.5(Ba,Ca)TiO3 - 0.5Ba(Zr,Ti)O3-15% CoFe2O4 was found to be around 6 ps/m. It was discovered that the constituent electromechanical coupling factor and magnetomechanical coupling factor might play a role on the ME response. To understand the role of magnetostrictive phase, it was modified with a non-magnetic Al3+ ion. The composite of 0.5(Ba,Ca)TiO3 - 0.5Ba(Zr,Ti)O3 - 50% Co(Fe1.5Al0.5O4 was found to possess 3-times larger converse ME coefficient compared to its unmodified counterpart. This enhancement was attributed to the improved effective piezomagnetic coefficient d/dH and increased initial permeability of the Al3+ modified CFO. Secondly, using the knowledge from the BCZT-CFO composites, NiFe2O4 (NFO) was introduced as the magnetostrictive phase which has initial magnetic permeability of 39 that is much larger than that of CFO. This provided an enhancement of around 400 % in the ME coupling in BCZT-30%NFO (converse ME coefficient of 45 ps/m) sample as compared with that of BCZT-50%CFO(Al) (11 ps/m). Hence it gave a substantial evidence that the most important properties to be considered to improve the ME response of two-phase composites are the initial magnetic permeability of the ferrite phase and the maximal elastic compliance of the piezoelectric phase. This discovery has a potential to open new horizons for tailoring of new ME materials. Thirdly, a two-phase system consisting of relaxor ferroelectric Ba(Ti, Sn)O3 combined with CFO was studied. This system is a unique example of two-phase systems in which the dielectric properties were almost entirely retained even in the composite, which is in contrast to the case in other non-relaxor-magnetostrictive composites reported here. The ME coupling of the composite consisting of Ba(Ti0.7Sn0.3)O3-20%CFO was much better than the normal ferroelectric-magnetostrictive composites studied for their magnetodielectric properties, previously. The correlation of the maximum of elastic compliance versus temperature and the induced ME versus temperature curves was highlighted, providing another evidence of the vital role electromechanical softness of the ferroelectric material on the stress/strain mediated ME coupling. Lastly, when the connectivity was changed from (0-3) to (2-2) which is a bilayer geometry, improved local direct ME coupling was observed, due to the better interface between the magnetostrictive phase and the ferroelectric phase. Bilayered thin films of CFO and BaTiO3 (BTO) were synthesized with pulsed laser deposition on two differently oriented substrates. TEM analyses revealed that the CFO layer had a better interface when it was grown on (111) oriented substrate in comparison to that of (100) oriented substrate. This is a discovery as there are no reports in literature on the growth bilayered thin films on (111) oriented substrate. Direct ME coupling studied with PFM under an applied dc magnetic field. The bilayered thin film on (111) oriented substrate has an improved ME coupling in comparison to that of bilayered thin film grown on the (100) oriented substrate

Damage detection in a fixed-fixed beam using natural frequency changes

This paper presents a damage detection technique which uses change in Frequency Response Function (FRF) and Modal Strain Energy (MSE) for damage detection in beam and truss like structures. It’s a robust approach for Structural Health Monitoring (SHM) using natural frequency for structural damage assessment. This technique couples FRF with Iterative Modal Strain Energy (IMSE) method to accurately localize and quantify the damage with only few frequencies, overcoming the limitation of mode shape based damage detection methods which requires mode shapes at full coordinates but damage is either over/underestimated. In the current approach, a damage detection algorithm is developed and validated by conducting numerical studies for a Fixed-Fixed beam, both noise-free and noise-effected cases are simulated. The numerical studies reveal that proposed algorithm is capable of identifying, localizing and quantifying the damage accurately at reduce computational cost

COMBINING ABILITY STUDIES OF GRAIN YIELD AND RELATED TRAITS IN PEARL MILLET

The present study was undertaken to explore the genetic architecture of pearl millet through combining ability analysis in a 5X5 diallel fashion. Both GCA and SCA mean squares were significant in grain yield, plant height, panicle length and days to flowering. However, these were non-significant for number of productive tillers and panicle girth. General combining ability estimates revealed that genotype MGP-322 was good general combiner for all the traits under study except for days to flowering for which MGP-335 and 13RBS-01 were good general combiners but these were poor general combiners for all other traits under study. The crosses MGP-322XMGP-328, MGP-322XMGP-335, MGP-328X13RBS-13, 13RBS-01X13RBS-13 and MGP-322X13RBS-01 were best specific combiners for grain yield and some other attributes respectively. All these crosses involved at least one good general combiner except MGP-328X13RBS-13. This suggested that good general combiners are the best tool in improving the crop yield by manipulating the genetic architecture. Combining ability variances revealed that although both GCA and SCA variances were important, however, SCA variances were higher than GCA variances suggesting that non additive type of gene action was more prominent in the inheritance of characters under study

Financial contagion and globalization : evidence from South Asian countries

This study investigates the contagion and globalization between the South Asian (Pakistan, India, Bangladesh and Sri Lanka) and five largest economies (US, UK, China, Japan and Germany) stock markets. Daily stock returns data from 1st July 1997 to 30th June 2015 consisting of total 4695 observation is analyzed. DCC GARCH is applied to calculate the conditional correlation coefficients to overcome the issue of heteroscedasticity. Null hypothesis of no globalization got rejected eleven times out of twenty while the hypothesis of no contagion got rejected six times. Further analysis of conditional correlation coefficients confirmed the impact of 9/11 attacks, Subprime mortgage crises and Europeans debt crises on the Indian market. Impact of 9/11 attacks also found on Pakistani and Sri Lankan stock exchanges, while Dhaka stock exchange remained independent of all shocks. In sum, the South Asian stock markets remained isolated from the global shocks except India. Isolation of South Asian stock markets from the global shocks is due to their lower integration with the global markets. This study provides some useful recommendations to the investors and policy makers. Results suggests that Indian stock exchange get contagion impact from the major economies, so authorities of India should have to take measure to decouple the market from the global shocks. The markets of Bangladesh, Sri Lanka and Pakistan are not properly integrated with global financial system, so the authorities of these countries should have to take proper steps to liberalize the markets. This paper presents the first empirical study on financial contagion and globalization of South Asian countries.peer-reviewe

Production and Maintenance in Industries: Impact of Industry 4.0

Purpose: Production industries are undergoing a digital transition, referred to as the fourth industrial revolution or Industry 4.0, as a result of rapidly expanding advances in information and communication technology. The purpose of this research is to provide a conceptual insight into the impact of unique capabilities from the fourth industrial revolution on production and maintenance tasks in terms of providing the existing production companies a boost by making recommendations on areas and tasks of great potential. Design/methodology/approach: A survey and a literature review are among the research methods used in the research. The survey collected empirical data using a semi-structured questionnaire, which provided a broad overview of the company's present condition in terms of production and maintenance, resulting in more comprehensive and specific information regarding the study topics. Findings: The study points out that, the implementation of I4.0-technology leads to an increase in production, asset utilization, quality, reduced machine down time in industries, and maintenance. Sensor technology, big data analysis, cloud technologies, mobile end devices, and real-time location systems are now being implemented to improve production processes and boost organizational competitiveness. Moreover, the study highlights that data acquired throughout the production process is utilized for quality control, predictive maintenance, and automatic production control. Furthermore, I4.0 solutions help companies to be more efficient with assets at each stage of the process, allowing them to have a stronger control on inventories and operational-optimization potential. Originality: The findings of the study was supported by empirical data collected through survey that provides an intangible understanding of the importance of distinctive capabilities from the I4.0 revolution on production and maintenance tasks. In this study, some recommendations and guidelines to enhance these tasks are provided that are vital for existing production companie

Studies on tracheorelaxant and anti-inflammatory activities of rhizomes of polygonatum verticillatum

Background: The present study describes the tracheorelaxant and anti-inflammatory effects of Polygonatum verticillatum which may support its medicinal use in hyperactive airway complaints and inflammatory disorders.Methods: The tracheorelaxant activity of crude extract of the rhizomes of P. verticillatum (PR) was assessed in isolated guinea-pig tracheal tissues immersed in tissue organ bath filled with Tyrode\u27s solution and a continuous supply of carbogen gas (95% O2 and 5% CO2). The contractile and relaxant responses of the tissue were measured using isometric transducers coupled with Power-Lab data acquisition system. The anti-inflammatory effect was evaluated in carrageenan-induced rat paw edema model, while the lipoxygenase inhibitory activity was performed in the in-vitro assay. Various chromatographic and spectroscopic techniques were used for the isolation and characterization of pure molecules.Results: In isolated guinea-pig tracheal preparations, PR caused complete inhibition of the high K+ (80 mM) and carbachol-induced contractions however, it was more potent against K+ than CCh, similar to verapamil. Pretreatment of the tissue with PR, displaced the Ca2+ concentration-response curves to the right, similar to that induced by verapamil, indicating the presence of Ca2+ channel blocking like activity. When tested on carrageenan-induced rat paw edema, PR demonstrated a marked reduction in edema with 65.22% protection at 200 mg/kg, similar to aspirin. In the in-vitro assay, PR showed lipoxygenase inhibitory activity (IC50: 102 ± 0.19 μg/mL), similar to baicalein. Bioactivity-guided fractionation led to the isolation of 2-hydroxybenzoic acid and β-sitosterol.Conclusions: These results indicate that the plant possesses tracheorelaxant, mediated possibly through a Ca2+ channel blockade mechanism, and anti-inflammatory activities, which may explain the medicinal use of this plant in airway disorders and inflammation

The study of removal chromium (VI) ions from aqueous solution by bimetallic ZnO/FeO nanocomposite with Siltstone: Isotherm, kinetics and reusability

In this study, nanocomposites of Baghanwala Siltstone (BSS) with ZnO (BSS/ZnO), FeO (BSS/FeO), and BSS/ZnO/FeO were successfully prepared for the removal of hexavalent chromium [(Cr (VI)] from aqueous solutions via a batch adsorption process. The characterization studies by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) found successful synthesis of the composites and demonstrated the occurrence of different active functional groups that played an active role in Cr ion adsorption. The effect of Cr initial concentrations (25–100 mg/L), adsorbent dose (0.5–2 g/L), pH (2–8), and contact time (0–160 min) on Cr remediation from contaminated water was examined. The order of Cr ion removal was BSS/ZnO/FeO (77–87%) \u3e BSS/ZnO (74–83%) \u3e BSS/FeO (71–77%) \u3e BSS (68–74%). The as-synthesized BSS/ZnO/FeO led to successful Cr removal (87%) at a 25 mg/L Cr concentration at pH 4.0. The Cr ion adsorption by the BSS/ZnO/FeO nanocomposite was well explained by the Langmuir adsorption isotherm model (R2 \u3e 0.99), while the kinetic experimental data was well fitted with the pseudo-second-order model (R2 \u3e 0.99). Among the as-synthesized adsorbents, the BSS/ZnO/FeO nanocomposite showed excellent stability and reusability in seven sorption cycles. The results showed that the as-synthesized BSS/ZnO/FeO nanocomposite had the greatest adsorption potential for removing Cr ions from contaminated water

Biomedical and photocatalytic applications of biosynthesized silver nanoparticles: Ecotoxicology study of brilliant green dye and its mechanistic degradation pathways

© 2020 Elsevier B.V. The preparation of nanoparticles from biological materials is an economic and environmentally friendly strategy with several advantages. The current study is focused to synthesize silver nanoparticles using Petroselinum crispum plant extract. Various characteristics of biologically synthesized AgNPs were determined with UV–Visible (UV/Vis) Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, and High-Resolution Transmission Electron Microscopy (HRTEM). The plasmonic resonance peak at 425 nm ensured the formation of AgNPs. The FTIR analysis showed that the as-synthesized particles contain alcoholic and polyphenolic constituents, which are responsible for their capping and reduction. The HRTEM results revealed spherical shape of AgNPs with size ranging from 25 to 90 nm. The as-synthesized particles demonstrated excellent antibacterial properties against Gram positive and Gram-negative bacteria. The antioxidant applications of the particles were determined with 2,2-diphenyle-1-picrylhydrazyl (DPPH). Moreover, the photocatalytic application of the synthesized AgNPs was evaluated for brilliant green dye (BG). The results demonstrated high degradation of BG due to small size and well-dispersed nature of AgNPs. Degradation products of BG were identified to suggest degradation pathways. The eco-toxicity of the BG and constituents derived from the dye were studied with Ecological Structure Activity Relationship (ECOSAR) software

Effect of Phytosynthesized Selenium and Cerium Oxide Nanoparticles on Wheat (Triticum aestivum L.) against Stripe Rust Disease

In this study, selenium nanoparticles (SeNPs) and cerium oxide nanoparticles (CeONPs) were synthesized by using the extract of Melia azedarach leaves, and Acorus calamusas rhizomes, respectively, and investigated for the biological and sustainable control of yellow, or stripe rust, disease in wheat. The green synthesized NPs were characterized by UV-Visible spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD). The SeNPs and CeONPs, with different concentrations (i.e., 10, 20, 30, and 40 mg/L), were exogenously applied to wheat infected with Puccinia striformis. SeNPs and CeONPs, at a concentration of 30 mg/L, were found to be the most suitable concentrations, which reduced the disease severity and enhanced the morphological (plant height, root length, shoot length, leaf length, and ear length), physiological (chlorophyll and membrane stability index), biochemical (proline, phenolics and flavonoids) and antioxidant (SOD and POD) parameters. The antioxidant activity of SeNPs and CeONPs was also measured. For this purpose, different concentrations (50, 100, 150, 200 and 400 ppm) of both SeNPs and CeONPs were used. The concentration of 400 ppm most promoted the DPPH, ABTS and reducing power activity of both SeNPs and CeONPs. This study is considered the first biocompatible approach to evaluate the potential of green synthesized SeNPs and CeONPs to improve the health of yellow, or stripe rust, infected wheat plants and to provide an effective management strategy to inhibit the growth of Puccinia striformis.This research was funded by projects APOGEO (Cooperation Program INTERREG-MAC 2014–2020, with European Funds for Regional Development-FEDER). “Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI) del Gobierno de Canarias” (Project ProID2020010134), and Fundación CajaCanarias (Project 2019SP43).Peer reviewe