Investigation of local geometrical structure, electronic state and magnetic properties of PLD grown Ni doped SnO₂ thin films

Sharma, Mayuri,Naji Aljawfi, Rezq,Kumari, Kavita,Chae, K.H.,Dalela, S.,Gautam, S.,Alvi, P.A.,Kumar, Shalendra Elsevier 2019 Journal of electron spectroscopy and related pheno Vol.232 No.-

<P><B>Abstract</B></P> <P>We have investigated the ferromagnetic behavior, electronic states and local geometrical structure of Ni (2 and 10 at %) doped SnO<SUB>2</SUB> thin films. The films were successfully fabricated with the help of pulsed laser deposition (PLD) technique on Si (100) substrate under ultrahigh vacuum (UHV) condition. X-ray diffraction (XRD) results revealed the single phase character of SnO<SUB>2</SUB> rutile lattice structure with P4<SUB>2</SUB>/mnm space group. The inclusion of Ni ions into SnO<SUB>2</SUB> matrix induced oxygen vacancy (Vo), enhanced the distortion in octahedral local symmetry and reduced the oxidation state of the host Sn<SUP>4+</SUP> (SnO<SUB>2</SUB>) to Sn<SUP>3+</SUP> (Sn<SUB>2</SUB>O<SUB>3</SUB>), these details have been estimated by Raman scattering, Near edge X-ray absorption fine structure (NEXAFS) spectra at Ni L<SUB>3,2</SUB> and O K edges. Further quantitative details on the local geometrical structure around Ni ions were obtained via fitting the experimental Fourier transforms EXAFS spectra |X(R)| with FEFF6 code. The magnetization measurements performed at room temperature (RT) infers that Ni doped SnO<SUB>2</SUB> films displayed ferromagnetic (FM) signal, and there was no significant difference in the saturation moments even with increase in the Ni content. Hence, the similarity in the observed magnetic behavior of the films seems relevant to the same crystal growth condition (UHV) and might not be limited directly to the Ni dopant concentrations. The FM signal and the role of surface defects have been discussed in the light of spin-split impurity band percolation mechanism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ni doped SnO<SUB>2</SUB> thin films were deposited on Si substrate (001) by PLD technique. </LI> <LI> NEXAFS at Ni L<SUB>3,2</SUB> edges confirmed that the Ni ions exist in high spin divalent ground state. </LI> <LI> The UHV assisted growth condition created a favorable condition for oxygen non-stoichiometry. </LI> <LI> A significant modification have be observed in the surface morphology. </LI> <LI> Magnetic behavior seems to be more relevant to the formation of VO<SUP>2+</SUP> at the surfaces. </LI> </UL> </P>

Ultrasonic-assisted synthesis of ZnTe nanostructures and their structural, electrochemical and photoelectrical properties

Ilanchezhiyan, P.,Mohan Kumar, G.,Xiao, Fu,Poongothai, S.,Madhan Kumar, A.,Siva, C.,Yuldashev, Sh.U.,Lee, D.J.,Kwon, Y.H.,Kang, T.W. Elsevier 2017 Ultrasonics sonochemistry Vol.39 No.-

<P><B>Abstract</B></P> <P>Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO<SUB>2</SUB> traces in ZnTe through the corresponding vibrations. Optical bandgap of the ZnTe suspension was estimated to be around 2.15eV, authenticating the direct allowed transitions. The <I>p</I>-type electrical conductivity and charge carrier density of ZnTe were additionally estimated from the Bode, Nyquist and Mott-Schottky type impedance plots. The photoelectrical properties of ZnTe were investigated by fabricating <I>p</I>-ZnTe/<I>n</I>-Si heterostructures and studying their corresponding current-voltage characteristics under dark and white light illumination. The diodes revealed excellent rectifying behaviour with significant increase in reverse current under illumination. The stability of the devices were also affirmed through the time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the integrated heterojunctions. The obtained results also augment the potential of sonochemically processed ZnTe for application in photo detection and sensor related functions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanostructured ZnTe were ultrasonically processed for photoelectronics. </LI> <LI> Raman, XPS and electron microscopic tools affirmed their physico-chemical traits. </LI> <LI> Electrical properties were studied using Nyquist and Mott-Schottky plots. </LI> <LI> <I>I</I>-<I>V</I> studies augment the improved photo response in p-ZnTe/n-Si heterojunctions. </LI> </UL> </P>

Ultrahigh electrically and thermally conductive self-aligned graphene/polymer composites using large-area reduced graphene oxides

Kumar, P.,Yu, S.,Shahzad, F.,Hong, S.M.,Kim, Y.H.,Koo, C.M. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.101 No.-

<P>In this work, for the first time we fabricated highly self-aligned large-area reduced graphene oxide/poly (vinylidene fluoride-co-hexafluoropropylene) (rLGO/PVDF-HFP) composite films through simple solution casting followed by low temperature chemical reduction process. The resulting free-standing rLGO/PVDF-HFP composite thin film revealed excellent electrical conductivity of similar to 3000 S/m and ultrahigh inplane thermal conductivity of similar to 19.5 W/mK at rLGO content of 27.2 wt %. This ultrahigh electrical and thermal conductivity were attributed to the good interfacial interaction, effective chemical reduction, high aspect ratio, and preferential orientation of graphene sheets along the film direction. We believe that our new fabrication procedure can be effectively used for large-scale production and commercialization of conductive composite materials for many thermal and electrical conduction applications. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Development of a compliant legged quadruped robot

Gor, M M,Pathak, P M,Samantaray, A K,Alam, K,Kumar, P,Anand, D,Vijay, P,Sarkar, R,Yang, J-M,Kwak, S W Springer-Verlag 2018 Sādhanā Vol.43 No.7

Enhanced protective potential of novel citronella essential oil microsponge hydrogel against Anopheles stephensi mosquito

Kumar Nitish,Kumar Sunil,Singh S.P.,Rao Rekha 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.1

Citronella oil has been frequently used as an insect repellant and antibacterial agent for management of vector borne diseases. In this study, the fabrication of citronella oil microsponge loaded hydrogel (HG-COMS) was conceptualized in order to provide future insight for developing delayed release formulation. The hydrogel was characterized for drug content, drug interaction studies, spreadability, texture analysis and in vitro occlusive behaviour and results were found satisfactory. Further, in vitro antimicrobial studies were carried out to compare the antimicrobial inhibitory potential of the HG-COMS against citronella oil loaded hydrogel (HG-CO). HG-COMS formulation showed better antimicrobial efficacy than HG-CO (zone of inhibition of E. coli, P. aeruginosa and S. aureus; with P value less than 0.01, 0.001 and 0.05, respectively). In addition, the safety (irritation potential) of the oil loaded hydrogel formulation was assessed by Hen’s Egg Test Chorioallantoic Membrane (HAT-CAM) method. Mosquito repellent activity against Anopheles stephensi (malaria vector mosquito) was also performed in a net cage having blood starved female mosquitoes. The repellent potential of prepared HG-COMS (34% repellency for 6 h) was found dependent on release of CO from the microsponges as well as from the gel matrix. HET-CAM test revealed that HG-COMS (irritation score: 6.43 ± 0.77) was found very promising in comparison to HG-CO (irritation score: 12.77 ± 0.36), and was thus, considered safer for dermal use. HG-COMS showed reduced frequency of application, no skin irritation and potential for controlling A. stephensi for longer time periods. Hence, HG-COMS is found as a promising eco-friendly protective option, to minimize the burden of mosquito-transmitted diseases, especially malaria in future.

Monocrotophos Induces the Expression of Xenobiotic Metabolizing Cytochrome P450s (CYP2C8 and CYP3A4) and Neurotoxicity in Human Brain Cells

Tripathi, V. K.,Kumar, V.,Pandey, A.,Vatsa, P.,Dhasmana, A.,Singh, R. P.,Appikonda, S. H.,Hwang, I.,Lohani, M. Humana Press 2017 Molecular Neurobiology Vol. No.

<P>Expression of various cytochrome P450s (CYPs) in mammalian brain cells is well documented. However, such studies are hampered in neural/glial cells of human origin due to nonavailability of human brain cells. To address this issue, we investigated the expression and inducibility of CYP2C8 and CYP3A4 and their responsiveness against cyclophosphamide (CPA) and organophosphorus pesticide monocrotophos (MCP), a known developmental neurotoxicant in human neural (SH-SY5Y) and glial (U373-MG) cell lines. CPA induced significant expression of CYP2C8 and CYP3A4 in both types of cells in a time-dependent manner. Neural cell line exhibited relatively higher constitutive and inducible expression of CYPs than the glial cell line. MCP exposure alone could not induce the significant expression of CYPs, whereas the cells preexposed to CPA showed a significant response to MCP. Similar to the case of CPA induced expressions, neural cells were found to be more vulnerable than glial cells. Our data indicate differential expressions of CYPs in cultured human neural and glial cell lines. The findings were synchronized with protein ligand docking studies, which showed a significant modulatory capacity of MCP by strong interaction with CYP regulators-CAR and PXR. Similarly, the known CYP inducer CPA has also shown significant high docking scores with the two studied CYP regulators. We also observed a significant induction in reactive oxygen species (ROS), lipid peroxides (LPO), micronucleus (MN), chromosomal aberration (CA), and reduction in reduced glutathione (GSH) and catalase following the exposure of MCP. Moreover, the expressions of apoptotic markers such as caspase-3, caspase-9, Bax, and p53 were significantly upregulated, whereas the levels of antiapoptotic marker, Bcl2, was downregulated after the exposure of MCP in both cell lines. These findings confirm the involvement of ROS-mediated oxidative stress, which subsequently triggers apoptosis pathways in both human neural (SH-SY5Y) and glial (U373-MG) cell lines following the exposure of MCP.</P>

Development of open-set test in Marathi language for assessing speech identification performance of native children

S. B. Rathna Kumar,Udit Saxena,P. Phani Krishna,Abhijeet Ramesh Shinde,Ketaki Vinayak Borkar 한국언어재활사협회 2020 Clinical Archives of Communication Disorders Vol.5 No.2

Purpose: Speech identification score (SIS) testing has been used in every phase of the audiological test battery. We developed an open-set test in Marathi for assessing the speech identification performance of native children. Methods: The development of the test took place in three phases which included the development of word lists, recording of word lists, and SIS testing. The developed test consisted of four word-lists with each list consisting of 15 monosyllabic words in CVC structure and 10 disyllabic words in CVCV structure. The recording was performed in a sound-treated room where ambient noise levels were maintained as per the permissible levels. SIS testing was performed on a total of 90 children with normal hearing who were equally divided into three groups. Groups I, II, and III consisted of children in the range between 6 and 6.11 years, 7 and 7.11 years, and 8 and 8.11 respectively. Results: The data were subjected to one-way ANOVA and the results revealed no statistically significant difference (p>0.05) in SIS between three groups for each word list and between four word-lists for each group. The overall groups’ mean SIS were 99.15%, 98.97%, 99.06%, and 99.02% for four word-lists respectively, and were falling within the normal range (90 to 100%). Conclusions: Findings of the present study are in line with the findings of research reports on other Indian languages. The four word-lists developed in the present study were found to be equally difficult, reliable, and valid test materials in Marathi for assessing native children.

Botanicals Mediated Reproductive Enhancement in Mulberry Silkworm (Bombyx mori L.)

( P. M. Pratheesh Kumar ),( S. K. Bhargava ),( C. J. Prabhakar ),( C. K. Kamble ) 한국잠사학회 2007 International Journal of Industrial Entomology Vol.14 No.1

Ethanol extract of 20 botanicals in 3 concentrations i.e., 2.5%, 5% and 10% were evaluated for their efficacy to improve reproductive performance of mulberry silkworm (Bombyx mod L.) through feeding botanical enriched mulberry leaves during 2nd day of 4th age as well as 1st and 3rd day of 5th age larvae. The preliminary screening was done by ranking the botanicals based on influence in most important reproductive contributing parameters such as single cocoon weight, effective rate of rearing, pupation rate, fecundity and recovery of eggs/kg cocoon. Five botanicals viz., Asparagus recemosus, Achyranthes aspera, Tribulus terrestris, Withania somnifera, Parthenium histerophorus ranked first were further evaluated at 8% 5% and 3% concentrations to confirm their effectiveness and standardize effective concentration. Among the rearing parameters, mature larval weight, shell ratio and number of cocoons/kg were not significantly influenced by the treatments. However, reproductive parameters such as effective rate of rearing (wt), pupation rate (%), fecundity (No.) and egg recovery (g)/kg cocoon were significantly (P<0.05) influenced by the botanicals. Higher fecundity and egg recovery were obtained on treatment with Withania somnifera irrespective of concentrations. However at 5% concentration, pupation rate, fecundity as well as egg recovery were found significantly higher than that of other concentrations, confirming its effectiveness for improving reproductive efficiency.

Magnetic ground state of the multiferroic hexagonal LuFeO3

Suresh, Pittala,Vijaya Laxmi, K.,Bera, A. K.,Yusuf, S. M.,Chittari, Bheema Lingam,Jung, Jeil,Anil Kumar, P. S. American Physical Society 2018 Physical Review B Vol.97 No.18

<P>The structural, electric, and magnetic properties of bulk hexagonal LuFeO3 are investigated. Single phase hexagonal LuFeO3 has been successfully stabilized in the bulk form without any doping by sol-gel method. The hexagonal crystal structure with P6(3)cm space group has been confirmed by x-ray-diffraction, neutron-diffraction, and Raman spectroscopy study at room temperature. Neutron diffraction confirms the hexagonal phase of LuFeO3 persists down to 6 K. Further, the x-ray photoelectron spectroscopy established the 3+ oxidation state of Fe ions. The temperature-dependent magnetic dc susceptibility, specific heat, and neutron-diffraction studies confirm an antiferromagnetic ordering below the Neel temperature (T-N) similar to 130 K. Analysis of magnetic neutron-diffraction patterns reveals an in-plane (ab-plane) 120 degrees antiferromagnetic structure, characterized by a propagation vector k = (0 0 0) with an ordered moment of 2.84 mu(B)/Fe3+ at 6 K. The 120 degrees antifferomagnetic ordering is further confirmed by spin-orbit coupling density functional theory calculations. The on-site coulomb interaction (U) and Hund's parameter (J(H)) on Fe atoms reproduced the neutron-diffraction Gamma(1) spin pattern among the Fe atoms. P-E loop measurements at room temperature confirm an intrinsic ferroelectricity of the sample with remnant polarization P-r similar to 0.18 mu(C) cm(2). A clear anomaly in the dielectric data is observed at similar to T-N revealing the presence of magnetoelectric coupling. A change in the lattice constants at T-N has also been found, indicating the presence of a strong magnetoelastic coupling. Thus a coupling between lattice, electric, and magnetic degrees of freedom is established in bulk hexagonal LuFeO3.</P>

Studies on the Comparative Performance of Victory-1, S-36 and Kanva-2 Mulberry Genotypes and their Impact on Silkworm Rearing under Telangana Conditions of Andhra Pradesh

( P. Venkataramana ),( T. V. S. Srinivasa Rao ),( P. Sreenivasulu Reddy ),( N. Suryanarayana ),( Vineet Kumar ),( A. Sarkar ) 한국잠사학회 2002 International Journal of Industrial Entomology Vol.5 No.2