Structural and optical properties of TiO₂ thin films derived by sol-gel dip coating process

Saini, K.K.,Sharma, S.D.,Chanderkant,Kar, M.,Singh, D.,Sharma, C.P. North-Holland 2007 Journal of non-crystalline solids Vol.353 No.24

Nanocrystalline thin films of titanium dioxide have been fabricated on glass and silica substrates from partially hydrolyzed precursor solution. These films were subjected to heat treatment for 1h at temperatures 100, 200, 300, 400, 500, 600, 700, 800 and 900<SUP>o</SUP>C and characterized by XRD, SEM, XPS and optical techniques. As deposited films are found to be amorphous and also contain hydroxyl and organic functional groups. Films heat treated above 100<SUP>o</SUP>C do not contain hydroxyl and organic functional groups. Microcrystalline behavior is observed in the films heat treated above 300<SUP>o</SUP>C. Crystallite size increases from ∼5 to 50nm as sintering temperature is increased from 300 to 700<SUP>o</SUP>C. Formation of anatase phase with c-axis length 7.03A is observed in the films annealed up to 700<SUP>o</SUP>C. These films peel off from the substrate beyond 700<SUP>o</SUP>C annealing temperature. Density as well as refractive index of the films increases with increase in annealing temperature up to 700<SUP>o</SUP>C. Refractive index is found to show Cauchys behavior. Transmission better than 70% is observed in the visible range. There is a strong absorption around 370nm, which is attributed to band gap absorption of the material.

In Vitro Studies on the Release of Intracelluar Prolactin from Lymphocytes Using Strees Related Amines and Hormones

Sharma, G.T.,Majumdar, A.C.,Gupta, L.K. Asian Australasian Association of Animal Productio 1999 Animal Bioscience Vol.12 No.7

Circulating lymphocytes collected from control and heat-stressed buffaloes were subjected to in vitro culture with glucocorticoids, epinephrine or serotonin and their effect, if any, on the release of intracellular prolactin (PRL) was studied using ELISA and C-ELISA techniques. It was noted from the study that PRL level was higher in lymphocytes than in plasma of the control and heat-stressed animals, and that the PRL levels increased in the plasma of heat-stressed animals compared to that of non stressed animals with a significant decrease in lymphocytic PRL content by heat stress. Epinephrine and serotonin significantly increased the release of intracellular PRL from the lymphocytes of both in the control and the heat-stressed buffaloes but release of PRL from lymphocyte was not significantly changed by cortisol treatment in both control and heat-stressed buffaloes as compared to epinephrine and serotonin in vitro. When lympocytes were incubated with serotonin, it caused drastic lysis of the lymphocytes but epinephirine and cortisol did not show any lysis. It may be concluded from this study that hormones like epinephrine or serotonin known to increase during stress, release intracellular PRL from lymphocytes, the satellite PRL storage/synthesizing organ of blood, although the mechanism of the release is different.

Influence of growth temperature and post-annealing on an n-ZnO/p-GaN heterojunction diode

Sharma, S.K.,Heo, S.,Lee, B.,Lee, H.,Kim, C.,Kim, D.Y. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.12

We report on an n-ZnO/p-GaN heterojunction diode fabricated from zinc oxide (ZnO) films at various growth temperatures (450, 500, 550, and 600 <SUP>o</SUP>C) by RF sputtering. The films were subsequently annealed at 700 <SUP>o</SUP>C in N<SUB>2</SUB> ambient. To investigate the influence of the growth temperature of n-ZnO films, the microstructural, optical, and electrical properties were measured using scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and Hall measurements. The XRD pattern showed the preferred orientation along the c-axis (002) regardless of growth temperature. The PL spectra showed a dominant sharp near-band-edge (NBE) emission. Current-voltage (I-V) curves showed excellent rectification behavior. The turn-on voltage of the diode was observed to be 3.2 V for the films produced at 500 <SUP>o</SUP>C. The ideality factor of ZnO film was observed to be 1.37, which showed the best performance of the diode.

Thickness Dependent Study of RF Sputtered ZnO Thin Films for Optoelectronic Device Applications

Shashikant Sharma,C. Periasamy,P. Chakrabarti 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.6

This work reports thickness dependent structural and optical studies of ZnO thin films grown over p-type silicon (Si) and glass substrates using RF sputtering technique. The effect of variation of thickness on different microstructural and surface morphological parameters such as lattice constant, grain size, dislocation density, residual stress, lattice strain and surface roughness have been studied. All samples under study exhibited a hexagonal wurtzite structure with preferential growth along the c-axis perpendicular to the surface. It has been observed that structural disorder, stress and strain in the film reduces and as a result the crystalline quality of deposited ZnO thin films improves with increasing thickness. Optical characterization of deposited films has been done using UVvisible spectrophotometer, ellipsometer and photoluminescence spectroscope. Transmittance spectra of all ZnO thin film samples (190 - 342 nm) have exhibit a high transmittance over 85% in the visible region, and refractive index was found to vary between 0.85 - 3.1 in UV-Visible wavelength region (300 - 800 nm). The optical bandgap recorded a marginal increase from 3.22 eV to 3.26 eV by varying the thickness from 190 - 342 nm. Effect of film thickness on other optical parameters such as absorbance, reflectance, urbach energy, dielectric constant and photoluminescence has also been analyzed and reported.

Ovarian Response and Profile of Plasma Sex Steroids in Goats Against Combined Administration of FSH and LH Isolated from the Pituitaries of Buffaloes

Taru Sharma, G.,Pande, J.K.,Sanwal, P.C.,Varshney, V.P. Asian Australasian Association of Animal Productio 1997 Animal Bioscience Vol.10 No.5

This study was designed to record the ovarian response towards a combined administration of heterologous buffalo FSH (buFSH) and LH (buLH) in goats. The impact of such a treatment on ovarian structures and on the plasma profile of the ovarian sex steroids (estradiol $17-{\beta}$ and progesterone) was studied. The buFSH and buLH were isolated from the buffalo pituitaries involving a procedure of ethanolic extraction, acetone precipitation followed by metaphosphoric acid - ammonium sulphate fractionation. Both gonadotrophin samples prepared were found biologically active and potent. There was an increase in the total number of follicles in the treated group ($12.66{\pm}1.24$) vis-a-vis the control group ($8.50{\pm}2.06$). However, the percentage ($51.48{\pm}6.37$) of large follicles were found reduced ($23.74{\pm}5.93$) following the treatment. Again the number of corpora lutea were observed significantly higher ($2.33{\pm}0.47C.L.$) in the treated group than (1 C. L.) in the control group. The peak plasma estradiol- $17{\beta}$ levels achieved, were much higher ($17.16{\pm}9.52pg/ml$) in the treated group, than the peak ($7.22{\pm}1.67pg/ml$) achieved in the control group. Similar trend was observed with respect to the progesterone levels (higher in the treated group). This study thus indicated that, a combined administration of heterologous buffalo FSH and LH to goats speeded up development of larger follicles nearing the ovulation stage. This population of the follicles subsequently got reduced and lead to the formation of the increased number of the corpora lutea observed in this study.

Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo

Yoon, Jinmi,Beers, Timothy C.,Dietz, Sarah,Lee, Young Sun,Placco, Vinicius M.,Costa, Gary Da,Keller, Stefan,Owen, Christopher I.,Sharma, Mahavir American Astronomical Society 2018 The Astrophysical journal Vol.861 No.2

<P>Understanding the evolution of carbon and iron in the Milky Way's halo is of importance because these two elements play crucial roles in constraining star formation, Galactic assembly, and chemical evolution in the early universe. Here we explore the spatial distributions of the carbonicity, [C/Fe], and metallicity, [Fe/H], of the halo system based on medium-resolution (R similar to 1300)spectroscopy of similar to 58,000 stars in the southern hemisphere from the AAOmega Evolution of Galactic Structure (AEGIS) survey. The AEGIS carbonicity map exhibits a positive gradient with distance, as similarly found for the Sloan Digital Sky Survey carbonicity map of Lee et al. The metallicity map confirms that [Fe/H] decreases with distance from the inner halo to the outer halo. We also explore the formation and chemical evolution history of the halo by considering the populations of carbon-enhanced metalpoor (CEMP) stars present in the AEGIS sample. The cumulative and differential frequency of CEMP-no stars (as classified by their characteristically lower levels of absolute carbon abundance, A(C) <= 7.1, for subgiants and giants) increases with decreasing metallicity and is substantially higher than previous determinations for CEMP stars as a whole. In contrast, that of CEMP-s stars (with higher A(C)) remains almost flat, at a value of similar to 10% in the range -4.0 less than or similar to [Fe/H] less than or similar to -2.0. The distinctly different behaviors of the CEMP-no and CEMP-s stars relieve the tension with population synthesis models assuming a binary mass-transfer origin, which previously struggled to account for the higher reported frequencies of CEMP stars, taken as a whole, at low metallicity.</P>

Microstructure, structural, optical and piezoelectric properties of BiFeO₃ nanopowder synthesized from sol-gel

Sankar Ganesh, R.,Sharma, S.K.,Sankar, S.,Divyapriya, B.,Durgadevi, E.,Raji, P.,Ponnusamy, S.,Muthamizhchelvan, C.,Hayakawa, Y.,Kim, D.Y. ELSEVIER 2017 Current Applied Physics Vol.17 No.3

<P>Nanocrystalline BiFeO3 (BFO) powder was synthesized by sol-gel method and subsequent annealed at 100-500 degrees C. The microstructural analysis of BFO nanopowder confirmed the perovskite like structure of spherical nanoparticles annealed at 500 degrees C. The Raman spectrum of BFO nanoparticles showed the rhombohedrally structure with the space group of R3c. The XPS spectrum of BFO nanopowder showed the peaks of Bi, Fe, and O at the binding energy of 158.8, 711.75 and 529.2 eV, respectively. The piezoelectric properties of BFO nanoparticles were evaluated by making the sandwiched structure of graphene/BiFeO3-PDMS/graphene. The fabricated piezoelectric device demonstrated an output voltage of 0.4 V by applying the normal pressure from human finger on the device. (C) 2016 Elsevier B.V. All rights reserved.</P>

Evaluation of the toxicity of different phytoextracts of Ocimum basilicum against Anopheles stephensi and Culex quinquefasciatus

Prejwltta Maurya,Preeti Sharma,Lalit Mohan,Lata Batabyal,C.N. Srivastava 한국응용곤충학회 2009 Journal of Asia-Pacific Entomology Vol.12 No.2

The larvicidal effect of the crude carbon tetrachloride, methanol and petroleum ether leaf extracts of a widely grown medicinal plant, Ocimum basilicum, against Anopheles stephensi and Culex quinquefasciatus was evaluated. Petroleum ether extract was found to be the most effective against the larvae of both mosquitoes, with LC50 values of 8.29, 4.57; 87.68, 47.25 ppm and LC90 values of 10.06, 6.06; 129.32, 65.58 ppm against A. stephensi and C. quinquefasciatus being observed after 24 and 48 h of treatment, respectively. The efficacy of petroleum ether was followed by that of the carbon tetrachloride and methanol extracts, which had LC50 values of 268.61, 143.85; 446.61, 384.84 ppm and LC90 values of 641.23, 507.80; 923.60, 887.00 ppm against A. stephensi after 24 and 48 h, respectively, and LC50 values of 24.14, 17.02; 63.48, 53.77 ppm and LC90 values of 295.38, 204.23; 689.71, 388.87 ppm against C. quinquefasciatus after 24 and 48 h of treatment, respectively. These extracts are highly toxic against mosquito larvae from a range of species; therefore, they may be useful for the management of mosquito larvae to control vector borne diseases. The larvicidal effect of the crude carbon tetrachloride, methanol and petroleum ether leaf extracts of a widely grown medicinal plant, Ocimum basilicum, against Anopheles stephensi and Culex quinquefasciatus was evaluated. Petroleum ether extract was found to be the most effective against the larvae of both mosquitoes, with LC50 values of 8.29, 4.57; 87.68, 47.25 ppm and LC90 values of 10.06, 6.06; 129.32, 65.58 ppm against A. stephensi and C. quinquefasciatus being observed after 24 and 48 h of treatment, respectively. The efficacy of petroleum ether was followed by that of the carbon tetrachloride and methanol extracts, which had LC50 values of 268.61, 143.85; 446.61, 384.84 ppm and LC90 values of 641.23, 507.80; 923.60, 887.00 ppm against A. stephensi after 24 and 48 h, respectively, and LC50 values of 24.14, 17.02; 63.48, 53.77 ppm and LC90 values of 295.38, 204.23; 689.71, 388.87 ppm against C. quinquefasciatus after 24 and 48 h of treatment, respectively. These extracts are highly toxic against mosquito larvae from a range of species; therefore, they may be useful for the management of mosquito larvae to control vector borne diseases.

Microstructure, structural, optical and piezoelectric properties of BiFeO3 nanopowder synthesized from sol-gel

R. Sankar Ganesh,Sanjeev K. Sharma,S. Sankar,B. Divyapriya,E. Durgadevi,P. Raji,S. Ponnusamy,C. Muthamizhchelvan,Y. Hayakawa,김득영 한국물리학회 2017 Current Applied Physics Vol.17 No.3

Nanocrystalline BiFeO3 (BFO) powder was synthesized by sol-gel method and subsequent annealed at 100e500 C. The microstructural analysis of BFO nanopowder confirmed the perovskite like structure of spherical nanoparticles annealed at 500 C. The Raman spectrum of BFO nanoparticles showed the rhombohedrally structure with the space group of R3c. The XPS spectrum of BFO nanopowder showed the peaks of Bi, Fe, and O at the binding energy of 158.8, 711.75 and 529.2 eV, respectively. The piezoelectric properties of BFO nanoparticles were evaluated by making the sandwiched structure of graphene/ BiFeO3-PDMS/graphene. The fabricated piezoelectric device demonstrated an output voltage of 0.4 V by applying the normal pressure from human finger on the device.

Optimization of hemicellulose recovery from black liquor using ZnO/PES ultrafiltration membranes in crossflow mode

Manorma Sharma,Cátia V.T. Mendes,Patrícia Alves,Licínio M. Gando-Ferreira 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Black liquor, one of the by-products of pulp and paper industry, is an underexplored resource with greatpotential for the recovery of valuable biopolymers such as lignin and hemicelluloses. In this work, thehemicellulose was recovered from this liquor, containing 17 % of total dissolved solids, using ZnO/polyethersulfone ultrafiltration membrane. The hemicellulose was concentrated into the retentatestream while lignin was permeated through these membranes. The effects of transmembrane pressure(1 to 4 bar), time (up to 8 h) and crossflow velocity (0.1 and 0.2 m/s) were studied for ultrafiltration processoperating in crossflow mode. The highest rejection of hemicellulose was achieved up to 90.7 ± 1.9 %at 4 bar. At 3 bar, the yield of hemicellulose was 90 % and 84 % for the volume reduction up to 60 % and78 %, respectively. Mathematical modeling was applied to analyze the membrane fouling mechanismresponsible for the flux reduction during filtration at constant pressure, as well as to predict the changesin hemicellulose and lignin concentration during the filtration process.