Showing papers by "Jitendra Kumar published in 2011"
24 Aug 2011
TL;DR: The results show that the presence of zinc increases the drug release percentage and that the drug was released in a controlled manner, and the ciprofloxacin-loaded hydroxyapatite nanoparticles have a good antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus.
Abstract: In bone disorders infections are common. The concentration of majority of antibiotics is very low in the bone tissue. A high local dose can be obtained from the ciprofloxacin-loaded hydroxyapatite nanoparticles. The present study is aimed at developing the use of hydroxyapatite and zinc-doped hydroxyapatite nanoparticles as a carrier for ciprofloxacin drug delivery system. The ciprofloxacin-loaded hydroxyapatite and zinc-doped hydroxyapatite have a good antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus. Hydroxyapatite and zinc-doped hydroxyapatite were prepared and characterized using X-ray diffraction, Transmission electron microscopy and inductively coupled plasma optical emission spectrometry. They were loaded with ciprofloxacin using optimized drug loading parameters. Drug loading, in vitro drug release and antimicrobial activity were analyzed. The influence of zinc on the controlled release of ciprofloxacin was analyzed. The results show that the presence of zinc increases the drug release percentage and that the drug was released in a controlled manner.
103 citations
01 Jan 2011
TL;DR: This chapter discusses legumes as a Model Plant Family, plant Genetic Resources and Conservation of Biodiversity, Seed Dormancy and Viability, and Post Harvest Technology.
Abstract: 1 History, Origin and Evolution 2 Biology and Floral Morphology 3 Domestication 4 Breeding for Improvement of Cool Season Food Legumes 5 Breeding for Improvement of Warm-season Food Legumes 6 Distant Hybridization and Alien Gene Introgression 7 Polyploidy 8 Cytology and Molecular Cytogenetics 9 Molecular Cytogenetics in Physical Mapping of Alien Introgressions 10 In vitro techniques 11 Microsporogenesis and Haploidy Breeding 12 Genetic Transformation 13 Male Sterility and Hybrid Production Technology 14 Mutagenesis 15 Breeding for Biotic Stresses 16 Breeding for Abiotic Stresses 17 Legume Improvement in the Acidic and less Fertile Soils 18 Genomic Approaches for Management of Abiotic Stresses 19 Molecular Breeding and Marker-assisted Selection 20 Underutilized Food Legumes 21 Legumes as a Model Plant Family 22 Plant Genetic Resources and Conservation of Biodiversity 23 Seed Dormancy and Viability 24 Post Harvest Technology 25 Value Addition and Trade
67 citations
TL;DR: In this article, an attempt has been made to prepare MgO nano-crystallites through decomposition of sol-gel derived magnesium oxalate dihydrate in air, oxygen and nitrogen ambient at 500, 600, 800, and 1000°C for 2 hours each and study them with regard to their phase, average crystallite size, morphology, and photoluminescence (PL) behaviour.
55 citations
TL;DR: It is reported that the nanocomposite prepared under optimum condition could prolong the release of ciprofloxacin compared with the ciprosxyapatite loaded with a natural polymer, alginate.
Abstract: Hydroxyapatite is a bioceramic which has a wide range of medical application for bone diseases. To enhance its usage, we have prepared ciprofloxacin loaded nano hydroxyapatite (HA) composite with a natural polymer, alginate, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods. The results show that the nano HA crystallites are well intact with the alginate macromolecules. For the composite system FT-IR and micro Raman results are reported in this paper. Studies on the drug loading and drug release have been done. The drug is pre-adsorbed onto the ceramic particle before the formation of composite. The thermal behavior of composite has been studied using thermo gravimetric analysis (TGA). This work, reports that the nanocomposite prepared under optimum condition could prolong the release of ciprofloxacin compared with the ciprofloxacin loaded hydroxyapatite.
48 citations
TL;DR: In this article, an attempt has been made to synthesize sulfur free Eu3+-activated M1−xMoO4:Eux3+ (M = Zn, Mg, Zn and Ca, Ni and Co; x = 0.68 and y= 0.32) close to known values.
Abstract: An attempt has been made to synthesize sulfur free Eu3+-activated M1−xMoO4:Eux3+ (M = Zn, Mg, Ca, Ni and Co; x = 0.2) phosphors by an oxalate sol–gel process. The process involves gel formation from solutions of metal nitrates in ethanol, ammonium heptamolybdate tetrahydrate in de-ionized water and oxalic acid in ethanol, digestion for 12 h, drying at 100 °C for 24 h, decomposition in air at 600 °C or above to yield fine grained powder exhibiting different morphologies, viz. distorted spherical agglomerates, dumbbell shaped particles, rectangular bars, faceted particles, ellipsoids or parallelepipeds. The optical absorption bands have been attributed to (i) ligand-to-metal charge transfer (LMCT), i.e., oxygen to molybdenum in the MoO42−group and (ii) f–f electron transitions (viz., 7F0 → 5L6 at 395 nm and 7F0 → 5D2 at 465 nm) of Eu3+ ions upon excitation with a wavelength of ∼395 nm, which occupy non-centrosymmetric metal (M) sites. Eu3+ ions exhibit a strong electric dipole 5D0 → 7F2 transition emitting red light at ∼612 nm with quantum efficiency in a 1.0 : 1.7 : 3.2 ratio for M0.8MoO4:Eu0.23+ (M = Mg, Zn and Ca) phosphors, respectively. Further, their CIE coordinates are (x = 0.68 and y = 0.32) close to known values (x = 0.665 and y = 0.331) of Y2O2S:Eu0.053+ red phosphor. Hence, M0.8MoO4:Eu0.23+ (M = Mg, Zn and Ca) phosphor can possibly be a potential alternative to Y2O2S:Eu0.053+ for fabrication of near UV InGaN based light emitting diodes. Yet, another phosphor of composition Co0.8MoO4:Eu0.23+ is shown to have promise for white light emission with its CIE coordinates as x = 0.279 and y = 0.245.
42 citations
TL;DR: In this article, Li and Mg co-doped zinc oxide (ZnO) thin films were deposited by spin coating technique using X-ray diffraction (XRD), Ultraviolet-Visible absorption spectra (UV-VIS), photoluminescence spectra(PL), x-ray photo electron spectroscopy (XPS) and Hall measurements.
33 citations
TL;DR: In this article, an attempt has been made to synthesize strontium cobaltite powder by a sol-gel process, using cobalt and cobalt nitrates as precursors.
29 citations
TL;DR: In this paper, the authors show that increasing the time (t) of calcination causes crystallite growth that follows the relation d = α − s exp (-t/τ), α = 18.1 nm, s = 9.6 nm and τ = 6.9h.
Abstract: TiO2 nanoparticles have been prepared by sol-gel process using titanium isopropoxide as a precursor with ethanol and water as solvents. The synthesis involves gel formation, digestion for 24h, drying at 100°C for 10h, and calcination in air at 500–800°C for 2h. The resulting powder has been studied with respect to phase(s), morphology, optical absorption and photo - luminescence (PL) behaviour. The calcination of dried sol-gel product at 500°C for 2h leads to formation of anatase phase that possesses a tetragonal structure (a = 3.785 A, c = 9.514 A, Z = 4), average crystallite size ~ 11 nm and band gap of 3.34 eV. Further, increasing the time (t) of calcination causes crystallite growth that follows the relation d = α – s exp (-t/τ), α = 18.1 nm, s = 9.6 nm and τ = 6.9h. However, calcination of sol-gel product at 800°C for 2h gives rise to a rutile phase (tetragonal a = 4.593A, c = 2.959A, Z = 2), average crystallite size ~ 25 nm and band gap of 3.02 eV. The anatase phase exhibits strong PL emission peaks (excitation wavelength 405 nm) at 2.06 and 1.99 eV due to defect levels within the energy band gap. This observation has been attributed to finite size effects occurring in nanoparticles.
20 citations
Journal Article•
TL;DR: Most tolerant and most sensitive pigepea genotypes were identified for future use in breeding for aluminum tolerance in pigeonpea.
Abstract: Aluminum toxicity is a major factor limiting pigeonpea productivity in acid soils of North-eastern states of India. However, information regarding screening of genotypes for aluminum tolerance in pigeonpea is meagre. The effects of five levels of aluminum concentrations (0, 10, 20, 30 and 50 µg ml -1 Al) on 32 pigeonpea genotypes were studied by four different methods: hydroponic and sand assays (growth response methods), root re-growth and hematoxylin root staining. Significant variability was noted for tolerance to aluminum toxicity among the pigeonpea genotypes. The results of all the four screening methods were consistent, suggesting that any one of the four methods could be used for screening purpose. However, due to operative simplicity, reliable and better precision and short test period, the hematoxylin staining at 30 µg ml -1 aluminum concentration was suggested as the best method to discriminate pigeonpea genotypes for aluminum tolerance. Based on the results, most tolerant (IPA 7-10, T 7and 67 B) and most sensitive (Bahar, Pusa 9 and Pusa 2002-2) genotypes were identified for future use in breeding for aluminum tolerance in pigeonpea.
19 citations
TL;DR: In this article, the effect of aluminum doping and annealing environment on morphology, optical transmittance and electrical resistivity of ZnO thin films has been studied with possible application as a transparent electrode in photovoltaic.
Abstract: Aluminum-doped ZnO thin films of high optical transmittance (∼ 84-100%) and low resistivity (∼ 2.3x10-2 Ωcm) have been prepared on glass substrate by the spin coating and subsequent annealing at 500°C for 1h in air or vacuum. Effect of aluminum doping and annealing environment on morphology, optical transmittance and electrical resistivity of ZnO thin films has been studied with possible application as a transparent electrode in photovoltaic. The changes occurring due to aluminum addition include reduction in grain size, root mean square roughness, peak-valley separation, and sheet resistance with improvement in the optical transmittance to 84-100% in the visible range. The origin of low electrical resistivity lies in increase in i) electron concentration following aluminum doping (being trivalent), formation of oxygen vacancies due to vacuum annealing, filling of cation site with additional zinc at solution stage itself and ii) carrier mobility.
17 citations
TL;DR: Theoretical calculations based on the density functional theory within Tight Binding Linear Muffin-tin Orbital (TBLMTO) method has been carried out to study the magnetic properties of cobalt doped GaN as mentioned in this paper.
TL;DR: In this paper, a large magnetocaloric effect has been observed in Mn3O4 around its ferrimagnetic transition at TN = 42.75 K. Field-induced isothermal entropy changes (ΔS) were derived from both magnetic and calorimetric techniques.
Abstract: Large magnetocaloric effect has been observed in Mn3O4 around its ferrimagnetic transition at TN = 42.75 K. Field-induced isothermal entropy changes (ΔS) were derived from both magnetic and calorimetric techniques. The maximum |ΔS| and adiabatic temperature change (ΔTad) at TN are 11 J kg−1 K−1 and 1.9 K, respectively, for a magnetic field change of 20 kOe. Moreover, it is found that the complex magnetic phase transitions taking place below TN produce additional—but smaller—features on ΔS(T).
TL;DR: In this paper, high-resolution X-ray diffraction (HR-XRD) analysis reveals the formation of Ga 2 O 3 due to the interface mixing of GaN/Al O 3 upon irradiation.
Abstract: Metal-organic chemical vapor deposition (MOCVD) grown n-type Gallium nitride (GaN) has been irradiated with 100 MeV Ni 9+ ions at room temperature. Atomic force microscopy (AFM) images show the nano-clusters' formation upon irradiation and the irradiated GaN surface roughness increases with the increasing ion fluences. High-resolution X-ray diffraction (HR-XRD) analysis reveals the formation of Ga 2 O 3 due to the interface mixing of GaN/Al 2 O 3 upon irradiation. FWHM values of GaN (0 0 0 2) increases due to the lattice disorder. Photoluminescence studies show reduced band edge emission and yellow luminescence (YL) intensity with the increasing ion fluences. Change in the band gap energy between 3.38 and 3.04 eV was measured by UV-visible optical absorption spectrum on increasing the ion fluences.
Journal Article•
TL;DR: A field experiment was carried out at Medicinal Plants Research and Development Centre (MRDC), G.B. Pant University of Agriculture and Technology, Pantnagar, during Rabi season of 2008-09 and 2009-10 to quantify the effect of integrated nutrient management (INM) on herbage yield of black henbane ( Hyoscyamus niger L.) as discussed by the authors.
Abstract: A field experiment was carried out at Medicinal Plants Research and Development Centre (MRDC) , G.B. Pant University of Agriculture and Technology, Pantnagar, during Rabi season of 2008-09 and 2009-10 to quantify the effect of integrated nutrient management (INM) on herbage yield of black henbane ( Hyoscyamus niger L.) . Soil of experimental field was sandy loam with pH 6.81, rich in organic carbon (0.92%) medium in available phosphorus (23.41 kg ha-1) and exchangeable potassium (209.42 kg ha-1), but low in available nitrogen (223.46 kg ha-1). The experiment was laid out in a randomized block design (RBD) with 12 treatments using inorganic fertilizers, vermicompost and biofertilizers ( Azotobacter and phosphate solubilizing bacteria) in different combinations including one control treatment. The treatments were control, recommended NPK (100:50:50 kg ha-1), 75% recommended NPK+2.5 tons ha-1 vermicompost (VC), 50% recommended NPK + 5.0 tons ha-1 VC, 25% recommended NPK + 7.5 tons ha-1 VC, 10 tons ha-1 VC, recommended NPK + biofertilizers, 75% recommended NPK + 2.5 tons ha-1 VC + biofertilizers, 50% recommended NPK + 5.0 tons ha-1 biofertilizers, 25% recommended NPK + 7.5 VC tons ha-1 + biofertilizers, 10 tons ha-1 VC + biofertilizers and biofertilizers alone. Dry herbage yield of H. niger increased with integrated application of inorganic and organic nutrients. A significant increase in herbage yield was observed with 75% recommended NPK + 2.5 tons ha-1 VC + biofertilizers followed by 75% recommended NPK + 2.5 tons ha-1 VC. It is therefore recommended that, 75 % recommended NPK along with 2.5 t ha-1 VC with or without biofertilizers is best to obtain maximum herbage yield of black henbane.
Journal Article•
TL;DR: Cane yield increased significantly with all the measures over weedy check and was highest under weed free conditions though it was at par with hoeing at 30, 60 and 90 day after transplanting (DAT).
Abstract: A field experiment was conducted during 2006–2008 to find out suitable dose of velper K4 60 WP for the control of weeds in spring planted sugarcane. Weed population and weed dry weight were reduced significantly due to different weed control measures. Cane yield increased significantly with all the measures over weedy check and was highest under weed free conditions (94.3 t/ha) though it was at par with hoeing at 30, 60 and 90 day after transplanting (DAT). Atrazine was the most effective herbicide reducing weed population and weed dry weight followed by Velpar. Weed growth in weedy plot caused 73.5% reduction in cane yield compared to weed free condition. Among herbicidal treatments, maximum cane yield of 82.4 t/ha was obtained in atrazine and no herbicide treatment was at par with this. Due to phytotoxicity reason Velpar K4 60 WP resulted in lower cane yield, though it effectively controlled the weeds.
TL;DR: In this article, the synthesis and solid state structural description of uranyl complexes of carboxylate functionalized adenine and uracil derivatives are described, and the metal coordination through a pendant leads to the formation of dimeric assemblies, whereas the directional nature of hydrogen bonding interaction supported by nucleobases and aqua ligands, result in the generation of complex 3-D architectures containing embedded nucleobase ribbons.
Abstract: We describe synthesis and solid state structural description of uranyl complexes of carboxylate functionalized adenine and uracil derivatives. The metal coordination through carboxylate pendant leads to the formation of dimeric assemblies, whereas the directional nature of hydrogen bonding interaction supported by nucleobases and aqua ligands, result in the generation of complex 3-D architectures containing embedded nucleobase ribbons.
Journal Article•
TL;DR: In this article, the most important causes of ultrasonic attenuation in solids are electron-phonon, phonon-Phonon interaction and that due to thermo elastic relaxation.
Abstract: Ultrasonic attenuation studies can be used to characterize material not only after production but during processing as well. The most important causes of ultrasonic attenuation in solids are electron-phonon, phonon-phonon interaction and that due to thermo elastic relaxation. The two dominant processes that will give rise to appreciable ultrasonic attenuation at higher temperature are the phonon-phonon interaction also known as Akhiezer loss and that due to thermo elastic relaxation are observed in calcium oxide crystal. At frequencies of ultrasonic range and at higher temperatures in solids, phonon-phonon interaction mechanism is dominating cause for attenuation. Ultrasonic attenuation due to phonon-phonon interaction (α/f 2 )p-p and thermo elastic relaxation (α/f 2 )th are evaluated in Calcium Oxide crystal up to an elevated temperature from 100 K - 1500 K along , and crystallographic directions. Temperature dependence of ultrasonic attenuation along different crystallographic direction reveals some typical characteristic features.
24 Oct 2011
TL;DR: In this article, aluminum-doped zinc oxide thin films have been deposited on glass substrates by R.F. sputtering using ZnO(98%)•Al2O3(2%) target in different sputtering gaseous environments, viz., Ar, Ar/O2 and Ar/N2+H2 at 80°C.
Abstract: Aluminum‐doped zinc oxide thin films have been deposited on glass substrates by R.F. sputtering using ZnO(98%)‐Al2O3(2%) target in different sputtering gaseous environments, viz., Ar, Ar/O2 and Ar/N2+H2 at 80°C. These films have been studied with regard to phase, microstructure, optical absorption and sheet resistance for application in photovoltaic devices as transparent conducting electrodes. The properties of the films are shown to strongly depend on the sputtering gas(es). The films exhibit a wurtzite‐type hexagonal structure with the (00.2) preferred orientation, the c‐axis perpendicular to the substrate. The intensity of 00.2 diffraction peak and the average crystallite size remain almost the same when the films are prepared under pure Ar or Ar/O2 environment. However the average crystallite size increases while electrical resistance decreases with introduction of nitrogen and hydrogen in comparison to oxygen in argon. Nevertheless, the optimum value of optical transmittance and sheet resistance of ...
TL;DR: In this paper, annealed, irradiated Schottky barrier (SB) solar cells were characterised using micro-Raman spectroscopy at three different regions: at the (1) ohmic contact region, (2) unirradiated region and (3) irradiated region.
Abstract: Gallium arsenide (GaAs) cells have been in the race with silicon single-crystal cells for the highest efficiency photovoltaic devices. The annealed, irradiated Schottky barrier (SB) solar cells were characterised using micro-Raman spectroscopy at three different regions: namely, at the (1) ohmic contact region, (2) unirradiated region and (3) irradiated region. We also present a micro-Raman study of the damage process in annealed GaAs SB solar cells bombarded by high-energy ions. A Gaussian line shape was fitted to the Raman spectra of the longitudinal optical phonon A1(LO), and parameters such as intensity, full width at half maximum (FWHM) and the area under the peak were obtained for the different annealing temperatures. Biaxial stress (σ), carrier concentration (n), depletion length (Ld), dislocation velocity (ν) and life time of the first-order optical phonon (τ) of the A1(LO) mode of the irradiated region of the samples annealed at different temperatures were calculated. Copyright © 2010 John Wiley & Sons, Ltd.
Journal Article•
TL;DR: PZN-PT single crystals have been grown at morphotrophic phase boundary by flux technique using PbO as flux and powder x-ray diffraction pattern of the grown crystals show that the peaks correspond to perovskite phases as mentioned in this paper.
Abstract: PZN‐PT single crystals have been grown at morphotrophic phase boundary by flux technique using PbO as flux. The powder x‐ray diffraction pattern of the grown crystals show that the peaks correspond to perovskite phases. Electrical characterizations such as dielectric properties, hysteresis measurement and piezoelectric measurement have been investigated and the results are discussed in detail.