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Rayleigh wave at imperfectly corrugated interface in FGPM structure
K. Hemalatha,S. Kumar,A. Akshaya Techno-Press 2023 Coupled systems mechanics Vol.12 No.4
The Rayleigh wave propagation is considered in the structure of the functionally graded piezoelectric material (FGPM) layer over the elastic substrate. The elastic substrate loosely bonds the layer through a corrugated interface, whereas its upper boundary is also corrugated but stress-free. Additionally, the solutions for the FGPM layer and substrate are derived using the fundamental variable separable approach to convert the partial differential equation to an ordinary differential equation. The results with boundary conditions lead to dispersion relations for the electrically open and electrically short cases in the determinant form. The outcomes have been numerically analyzed using a specific model. The findings were presented in the form of graphs, which were created using Mathematica 7. Graphs are plotted for variations in wavenumber and phase velocity. The outcomes may help measure interface defects and design Surface Acoustic Wave (SAW) devices.
La-doped ZnO nanoflower as photocatalyst for methylene blue dye degradation under UV irradiation
Hemalatha, P.,Karthick, S. N.,Hemalatha, K. V.,Yi, M.,Kim, H. J.,Alagar, M. Springer Science + Business Media 2016 Journal of materials science Materials in electron Vol.27 No.3
<P>Lanthanum doped ZnO flower-like structured nanoparticles were synthesized through microwave assisted sol-gel technique. X-ray diffraction, scanning electron microscopy, transmission electron microscopy analysis confirmed the size, structural morphology and successful compound formation of the samples. The band gap was calculated from Tauc's plot using UV-Vis spectroscopy data. Lanthanum doped ZnO nanoparticles were used for the photocatalytic degradation of methylene blue dye under UV light irradiation. Compared to pure ZnO sample, La-doped samples exhibited higher photocatalytic dye degradation under UV light irradiation with short time duration. Among the different amounts of dopant, 3 mol% La-doped ZnO nano rods showed the highest degradation with short time UV light irradiation (60 min). Other factors such as particle size, morphology and defects also affect the photocatalytic activity. In our study, the main factor that influence photocatalytic activity is the separation of photo induced electron-hole pair due to defects formation in the sample. The 3 mol% sample has the appropriate electron-hole separation due to defects compared to pure ZnO. The influence of defects on the photocatalytic activity of all samples has been revealed using photoluminescence spectroscopy analysis. Furthermore, the effect of various operational parameters such as photocatalyst quantity, dye concentration and dopant concentrations were also optimized.</P>
Ch. Hemalatha,K. Suresh Babu,G. Narsinga Rao 한국자기학회 2020 Journal of Magnetics Vol.25 No.3
Pure and Mn (2.5 %, 5 % and 10 %) doped CuO nanoparticles were synthesized via chemical process of ultrasonic spray pyrolysis method. The crystal structure and grain size of the particles were determined using XRD. The optical properties of the samples were investigated using UV- Visible spectroscopy. The SEM micrographs revealed the surface morphology of sphere-shaped particles in all samples. The ZFC magnetization exhibits a sharp peak at 32 K and the FC magnetization saturated below this peak temperature. This is a characteristic feature of typical spin-glass behavior. In addition, the AC conductivity curves show an increasing conductivity value with increasing Mn content. The enhanced conductivity is due to the Mn doping in CuO induce defects in grain boundary.
Mohd Shahanbaj Khan,Manish K. Pandey,S. Hemalatha 한국작물학회 2018 Journal of crop science and biotechnology Vol.21 No.5
Plants are sessile organisms that experience various abiotic stresses during their lifespan and try to adapt to these environmental stresses by manipulating their physiological, biochemical, cellular, and molecular mechanisms. Salinity is one of the important abiotic stress that affects the metabolism and physiology of plant cells that leads to serious damage to crops and productivity. We investigated the response of two contrasting (salt susceptible and tolerant) cultivars during saline stress by modulating its effect with the application of an important natural biostimulant panchagavya (PG). The results showed that the salinity stress greatly influenced and negatively affects the plant growth, biochemical attributes, and induces the expression of various genes in both cultivars. Furthermore, we assessed the effect of PG alone and by amending with NaCl to alleviate the saline stress which showed a significant enhancement of biochemical and physiological characteristics in both cultivars. Furthermore, we assessed the response of seven autophagy associated gene (ATG1, ATG3, ATG4, ATG6, ATG7, ATG8, and ATG9), BAX Inhibitor -1 (BI-1), Mitogen activated Protein Kinase – 1 (MAPK-1), WRKY53, Catalase -1 (CAT-1), Superoxide Dismutase (SOD), and Glutathione Peroxidase (GPX) genes in rice that displayed the differential expression pattern during saline stress in both cultivars. We concluded that saline stress can be manipulated by the application of PG and positively regulate the physiological, biochemical, and gene expression response in salt-susceptible and -tolerant rice cultivars. Furthermore, the current study also suggested that salinity is a mutifactorial and multigenic response. Autophagy and programmed cell death regulated along with salinity and was helpful in adapting the tolerance against the stress condition.
Selvam, S.,Balamuralitharan, B.,Karthick, S. N.,Hemalatha, K. V.,Prabakar, K.,Kim, Hee-Je The Royal Society of Chemistry 2016 Analytical methods Vol.8 No.44
<▼1><▼1><P>A self-powered supercapacitor based on a caffeine sensor electrode has been developed using an electrochemically deposited rGO/β-CD/MnO2 ternary composite with ionic liquid assistance.</P></▼1><▼2><P>A self-powered supercapacitor based on a caffeine sensor electrode has been developed using an electrochemically deposited rGO/β-CD/MnO2 ternary composite with ionic liquid assistance. This typical composite electrode was prepared from electrochemically reduced e-rGO followed by the addition of β-cyclodextrin and MnO2 from Mn(CH3COOH)2·4H2O on FTO surfaces. The composite material is indexed to the corresponding crystalline phase of MnO2 in the XRD investigation and Mn 3p, Mn 2p, C 1s, and O 1s signals were identified from XPS analysis. The cyclic voltammetry study reveals that the potential of the caffeine samples and the square wave voltammetry peak currents indicate an increasing trend for caffeine oxidation. The sensor expressed a sensitivity of 0.187 μA cm<SUP>2</SUP> μM<SUP>−1</SUP> with a linear range of 10–550 μM (<I>n</I> = 3.12). The corresponding supercapacitor also exhibited a specific capacitance of 352 F g<SUP>−1</SUP> and it showed a very good life time from a long term cyclic test. The proposed ternary composite electrodes may be suitable electrodes for self-powered sensor devices.</P></▼2></▼1>
Dhandapani, C.,Narayanasamy, R.,Karthick, S.N.,Hemalatha, K.V.,Selvam, S.,Hemalatha, P.,kumar, M. Suresh,Kirupha, S. Dinesh,Kim, Hee-Je Elsevier 2016 OPTIK -STUTTGART- Vol.127 No.22
<P><B>Abstract</B></P> <P>Nanocrystalline ZrO<SUB>2</SUB> and neodymium doped ZrO<SUB>2</SUB> (Nd–ZrO<SUB>2</SUB>) were successfully prepared by a polymer- assisted, sol-gel method and characterized by XRD, SEM, HRTEM, XPS and UV–vis techniques. X-Ray diffraction studies revealed the formation of highly crystalline structures of ZrO<SUB>2</SUB> and (Nd–ZrO<SUB>2</SUB>) samples. SEM images proved the evenly distributed nano - structured, spherically - shaped ZrO<SUB>2</SUB> particles of size 40nm, which was reduced to 20nm, when doped with neodymium. Light absorption properties of the nanoparticles were studied by UV–vis spectrophotometer. Nd - doped ZrO<SUB>2</SUB> was having a band gap of 2.8ev, while that of ZrO<SUB>2</SUB>, was 2.6ev. Thus, Nd substituted ZrO<SUB>2</SUB> effected substantial shifting of the absorption edge of zirconium oxide to red and resulting in the enhancement of visible light absorption The increase in band gap of Nd–ZrO<SUB>2</SUB> was resulted in an increasing light absorbtion tendency of Nd−ZrO<SUB>2</SUB>, which promoted the photocatalytic efficiency of it. XPS results confirmed substitution of Nd in ZrO<SUB>2</SUB>. Photocatalytic results for the degradation of methylene blue had indicated the fact that neodymium substitution dramatically enhanced the catalytic activity of zirconium oxide. This means that the neodymium − substituted zirconium oxide has the highest photocatalytic activity under visible light irradiation.</P>