Browsing by Author "Prabhakar Singh"

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A Study on Dunaliella salina Under Selected Nutrient Manipulation with Reference to the Biomass, Lipid Content Along with Expression of ACCase and RuBisCO Genes
(Springer, 2023) Sk Riyazat Khadim; Abhishek Mohanta; Prabhakar Singh; Priyanka Maurya; Ankit Kumar Singh; Arvind Kumar Singh; Ravi Kumar Asthana
Energy crises and climate change attracted less-explored microalgae as renewable resources. Deficiencies of nitrogen and phosphorus are the most effective inducers of lipid accumulation in microalgae but at the cost of biomass productivity. Therefore, nitrogen, phosphorus, and carbon manipulation of the culture medium was adopted for maximizing lipid as well as biomass production in Dunaliella salina. Phosphate deficiency in combination with 1.25 mM KNO3 (1/8 of the basal) resulted in higher lipid content (341.1 mg g−1 dry cell weight, DCW), but lower biomass (13.12 mgL−1d−1 DCW). The addition of 10.00 mM NaHCO3 to such cultures enhanced not only lipid content to 1.17-fold but also biomass productivity to 2.25-fold. The increase in biomass may be correlated with the stress-ameliorating effects of bicarbonate augmentation which helped in maintaining the health of the cells, as reflected by robust photosynthetic performance. The two important enzymes, RuBisCO and ACCase were also monitored for their expressions. RuBisCO possesses large and small subunits (rbcL and rbcS) responsible for incorporation of CO2, and beta carboxyl transferase (accD) of the heteromeric ACCase is associated with the first and committed step of fatty acid biosynthesis. Enhanced biomass and lipid content in D. salina cells after NaHCO3 augmentation may be ascribed to 6.23-fold increase in the expression of accD and > 2.16-fold increase in rbcL and rbcS genes. Thus, the present work recommends a threshold level of nitrogen and bicarbonate in phosphate deficient D. salina cultures for simultaneously maximizing the biomass and lipid content. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
A Study on Mixotrophic Approach for Maximizing Lipid Production in a Hypersaline Microalga, Dunaliella salina
(Springer, 2023) Abhishek Mohanta; Sk Riyazat Khadim; Prabhakar Singh; Laxmi; R.K. Asthana
The microalga, Dunaliella salina, is a treasure of fine chemicals, carotenoids, and lipids of industrial importance. The present investigation focused on the maximization of lipid content in the context of biofuel. Mixotrophic cultures growing in different combinations of sodium bicarbonate (NaHCO3) and glucose (Glu) or sodium acetate (Na-Ace) were monitored for essential growth parameters such as photosynthesis, dry biomass, and Chl a content. The maximum photosynthetic quantum yield (Fv/Fm) of all the screened mixotrophic cultures along with control ranged between 0.63 and 0.72, indicating the cells were in a good physiological state. The highest biomass productivity (33.46 ± 0.58 mg/L/d) was recorded in 1.0 mM NaHCO3 + 1.0 mM Glu-containing cultures. However, the highest lipid content (56% DCW) was recorded in 1.0 mM NaHCO3 + 0.5 mM Na-Ace-containing cultures. Interestingly, a 1.7-fold higher starch content (72.3 μg/mL) was recorded in 0.25 mM NaHCO3 + 0.5 mM Na-Ace over 1.0 mM NaHCO3 + 0.5 mM Na-Ace-containing cultures. Thus, data indicated that the higher concentration of NaHCO3 along with Na-Ace favoured lipid biosynthesis, while the lower concentration of NaHCO3 with Na-Ace favoured starch synthesis. Thus, substrate provision determined the desired products. Lipids obtained from D. salina at stage II (nitrogen-deficient condition) possessed ideal fuel properties according to international standards of EN 14214 and ASTM D6751. Therefore, the present work explored the threshold level of bicarbonate along with Na-Ace which was able to maintain good physiological status and produced higher lipids with better biodiesel properties. Graphical Abstract: [Figure not available: see fulltext.] © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Advancements in bifunctional catalysts for unitized regenerative fuel cells: exploring polaronic conduction and heterostructure designs
(Institute of Physics, 2024) Uma Sharma; Pardeep K Jha; Priyanka A Jha; Prabhakar Singh
This study investigates the development and performance evaluation of a bifunctional catalyst tailored for unitized regenerative fuel cells (URFCs), capable of facilitating both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in fuel cell and electrolyzer modes. The primary challenge addressed is the creation of electrocatalysts exhibiting high activity and corrosion resistance for oxygen reduction and water oxidation at the oxygen electrode. A novel catalyst structure based on La0.5Sr0.5Fe0.5Ti0.5O3(LSFT), i.e. LSFT/ZnO/LSFT with a thickness of ∼ 2 μ m, is explored within an environmentally friendly medium. This catalyst demonstrates superior performance characteristics, including reduced overpotential in HER and enhanced stability during oxygen/hydrogen evolution processes in neutral medium. This study identifies the formation of interfacial polarons and polaronic charge modulation resulting from the incorporation of ZnO in LSFT, leading to multifunctional OER/HER behavior. Notably, the proposed interfacial small polaron mechanism offers valuable insights into complex interfacial phenomena and holds promise for applications in diverse heterostructures involving layered 2D materials and transition metal oxides. Moreover, the robust LSFT/ZnO/LSFT catalyst exhibits exceptional stability, maintaining for 168 h of oxygen evolution at a constant potential of approximately 1.66 V for a current density of 1 A cm−2 in a neutral medium. These findings mark a significant advancement in URFC technology and present promising avenues for clean energy storage solutions. © 2024 IOP Publishing Ltd.
Analysis of U-slot loaded Patch for Dualband Operation
(International Academy of Microwave and Optical Technology (IAMOT), 2008) J.A. Ansari; Satya Kesh Dubey; Prabhakar Singh; R.U. Khan; Babau R. Vishvakarma
The analysis of U- slot loaded patch is carried out using equivalent circuit concept. The antenna exhibits dual resonance and the separation between two resonances is sensitive to the dimension of the slot. The theoretical results are compared with the simulated data using IE3D software which are in close agreement. Further radiation pattern is found to be invariant with the slot dimensions. © 2008 ISRAMT. All Rights Reserved.
Anisotropic photoconduction in ultrathin CuO: A nonreciprocal system?
(American Institute of Physics Inc., 2022) Ashish K. Ranjan; Priyanka A. Jha; Pardeep K. Jha; Prabhakar Singh
With the recent global surge in the research on perovskite halides, CuO is one of the binary oxides, which gets attention as a hole transport material. In centrosymmetric CuO, parity-time (P T) violation leads to photoconduction. The P Tsymmetry can be preserved if the system were non-reciprocal. Thus, in the current work, we fabricated an ultra-thin film of CuO using pulsed laser deposition and observed anisotropic photoconduction. The semiconductor parameters estimated from the photoresponse suggest that the relative value of free charge carrier density is neither altered significantly with thickness reduction nor with light exposure as it is quite low (∼10 - 7) suggesting high trap (deep) density. Further, anisotropic photocurrent in the absence of an electric field suggests the alteration in electromagnetic potential due to the existence of self-biasing and structural asymmetry. The application of Gauge field variance on 2D photonic metasurface reveals the non-chiral nature. It is suggesting T-symmetry breaking, and, therefore, the possibility of the photonic Aharonov-Bohm effect is expected in CuO thin films. © 2022 Author(s).
Anomalous electrical properties of poly vinyl alcohol films with Tb3+ ions and copper nanoparticles in different solvents
(Royal Society of Chemistry, 2015) Brijesh Kumar; Gagandeep Kaur; Prabhakar Singh; S.B. Rai
Laser ablation was used to fabricate copper nanoparticles (NPs) in different solvents from sodium lauryl sulphate, acetone and ethanol by applying 1064 nm radiation from a Nd:YAG laser. The sizes and shapes of the colloidal Cu NPs were investigated by transmission electron microscopy (TEM). The electrical conductivities of Tb3+ in polymer films with Cu NPs were measured in the frequency range of 20 Hz to 1 MHz and the temperature range of 308-343 K. It was found that the electrical conductivity of Tb3+ was greater for larger Cu NPs with sizes ranging from 20-40 nm in ethanol as compared to Cu NPs with smaller dimensions formed in the other two solvents. It was concluded that using ethanol as the solvent enhanced the electrical conductivity of Tb3+ in the polymer film. The activation energy as well as the variation in the loss tangent with temperature also explains the enhanced electrical conductivity. This journal is © The Royal Society of Chemistry 2015.
Bandgap and electrochemical engineering for disordered LaFeO3
(American Institute of Physics Inc., 2022) Uma Sharma; U.K. Kailash Veerappan; Pardeep K. Jha; Priyanka A. Jha; Prabhakar Singh
Being a charge transfer Mott insulator with low metal-insulator temperature, disordered LaFeO 3 (as an air electrode) is a potential material for electrochemical engineering. High electronic conductivity and inexpensive catalytic activity are the prime requisites for electrode materials. Here, we systematically substituted hole (Sr) at La-site and electron (Ti) at Fe-site. Our objective is here twofold, first to get material with improved catalytic behavior and to understand the role of bandgap engineering. All the investigated samples are oxygen-rich and show orthorhombic(Pbnm) phase at 300 K. The prominent cation vacancies are closely associated with the self-trapping of carriers. These trapping centers may be detrimental if they shift toward conduction band minima. However, this energy shift can be controlled with proper selection of substitution but require intricate understanding. At 300 K, we observe higher conductivity with band shrinkage for hole substitution, i.e., La 0.5Sr 0.5FeO 3 (LSF). A field dependent electrical study reveals trap free conduction for the hole substituted sample while undoped and compensated show ohmic conduction. Our results suggest that there is a correlation between band tuning and corrosion resistance. Dynamic numerical simulation, where interfacial electrochemical behavior up to 4000 s is studied, suggests that LSF has the least surface charge degradation. Experimentally, LSF proves to be a robust and efficient electrode due to chronopotentiometry stability with a potential of 2 V (vs Ag/AgCl) at a higher current of 150 mA/cm 2 in neutral media. Further, this study provides concomitant charge dynamics for these samples and the foster mechanism to get better air electrodes. © 2022 Author(s).
Bandgap engineering in TiO2/rGO 1D photonic metasurfaces as broadband solar absorber
(American Institute of Physics Inc., 2022) Yash K. Saurabh; Priyanka A. Jha; Pawan K. Dubey; Pardeep K. Jha; Prabhakar Singh
Inability to use full solar energy, especially near infrared radiation (NIR: 780-1400 nm), is one of the major limitations for solar energy harvesting due to the narrow bandgap (electronic as well as photonic). In this work, we designed the 1D photonic metasurfaces of TiO 2 with reduced graphene oxide (rGO) in an attempt to obtain broader absorption bandwidth in NIR. Further, to realize this experimentally, graphene oxide reduced TiO 2 nanocomposites are synthesized using the hydrothermal method to form a quantum well. The composites are observed in the anatase phase of TiO 2 with graphitic reflection, and microstructural studies that indicate the conversion of TiO 2 nanoparticles into nanotubes with reduced graphene oxide intercalation forming a kind of self-assembled metasurfaces. UV-vis absorption studies indicate a significant reduction in bandgap energy; typically, the indirect bandgap reduces near to zero. The experimental and numerical simulation results suggest phonon scattering dominated free carrier absorption in NIR in the TiO 2/rGO metasurface leading to wide broadband absorption (700-10 000 nm). © 2022 Author(s).
Bandgap tuning for transition metal oxides via PEGylation
(Institute of Physics, 2025) Priyanka A. Jha; Jay N. Mishra; Gargi Yadav; Harinder Kumar Tanti; Ashish K. Ranjan; Pardeep K. Jha; Prabhakar Singh
Bandgap engineering is controlled manipulation of the bandgap of materials/meta-materials to achieve desired properties. The electrical and optical properties of materials are significantly affected by bandgap tuning; therefore, bandgap engineering is a powerful technique for designing electronic and optoelectronic devices. Compositional engineering, strain engineering, and nanoscience and technology are the three major fields associated with bandgap engineering. Any unique combination of this engineering can provide novel strategies to produce novel band-structured devices. In this method article, we have demonstrated how solvation energy can alter the bandgap energy, a fact that is generally ignored due to misconceptions about quantum/size confinement. Here, we prepare nanostructured transition metal oxides (Co3O4, CuO, and ZnO) with polyethylene glycol (PEG), and the method is termed PEGylation. We investigate the influence of PEGylation on the structural, electrochemical, and electronic nature of these oxides. It is observed that the bandgap tunability (7.33%) is maximum for ZnO. Our study suggests that band alteration is significantly correlated with the change in lattice parameters; however, it is orientation dependent as the correlation coefficient reduces to 0.85 from 1 for the change in lattice parameter b along the y-axis compared to the other two lattice parameters. Similarly, band alteration is also known to have some correlation with the electrochemical potential, but is surprisingly almost independent of size confinement. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Bioaccumulation of selenium in halotolerant microalga Dunaliella salina and its impact on photosynthesis, reactive oxygen species, antioxidative enzymes, and neutral lipids
(Elsevier Ltd, 2023) Prabhakar Singh; Sakshi Singh; Priyanka Maurya; Abhishek Mohanta; Hardik Dubey; Sk. Riyazat Khadim; Ankit K. Singh; Adarsh K. Pandey; Arvind K. Singh; Ravi K. Asthana
Selenium (Se) is an essential element for living systems, however, toxic at higher levels. In the present study, Dunaliella salina cells were exposed to different Se concentrations for their growth (EC50 195 mg L−1) as well as Se accumulation. The cells exposed to 50 mg L−1 Se showed photoautotrophic growth parallel to control and accumulated 65 μg Se g−1 DW. A decrease in photosynthetic quantum yield, chlorophyll content, and the increase in intracellular reactive oxygen species, proline content, and lipid peroxidation accompanied by higher neutral lipid accumulation, were recorded at higher Se level. The enzymes superoxide dismutase and catalase played a pivotal role in antioxidative defense. Heterogeneity in accumulated carotenoids at varying concentrations of selenium was prevalent. The cells exposed to 200 mg L−1 Se resulted in the disorganization of organelles. Thus, the Se enriched biomass obtained at 50 mg L−1 may be explored for bio-fortification of food and feed. © 2023 Elsevier Ltd
Biochemical and physiological characterization of a halotolerant Dunaliella salina isolated from hypersaline Sambhar Lake, India
(Blackwell Publishing Inc., 2019) Prabhakar Singh; Riyazat Khadim; Ankit K. Singh; Urmilesh Singh; Priyanka Maurya; Anupam Tiwari; Ravi K. Asthana
The objective of the present study was to characterize intrinsic physiological and biochemical properties of the wall-less unicellular cholorophyte Dunaliella salina isolated from a hypersaline Sambhar Lake. The strain grew optimally at 0.5 M NaCl and 16:8 h L:D photoperiod along with maintaining low level of intracellular Na + even at higher salinity, emphasizing special features of its cell membranes. It was observed that the cells experienced stress beyond 2 M NaCl as evidenced by increased intracellular reactive oxygen species and antioxidative enzymes, nevertheless proline and malondialdehyde content declined sharply accompanied by higher neutral lipid accumulation. Salinity exceeding 2 M resulted decrease in photosynthetic quantum yield (Fv/Fm) and enhanced glycerol synthesis accompanied by leakage. Super oxide dismutase seemed to play a pivotal role in antioxidative defense as eight isoforms were expressed differentially while catalase and glutathione peroxidase showing no significant change in their expression at higher salinity. The ability of D. salina to grow in range of salinities by sustaining healthy photosynthetic apparatus along with accumulation of valuable products made this alga an ideal organism that can be exploited as resource for biofuel and commercial products. © 2018 Phycological Society of America
Biofabrication of silver oxide nanoparticles (So-np) by autolysate of pseudomonas mendocina pm1, and assessment of its antimicrobial/antibiofilm potential
(National Institute of Science Communication and Information Resources, 2021) Venkatesh Chaturvedi; Piyoosh Kumar Babele; Prabhakar Singh
Silver oxide Nanoparticles (SO-NP) exhibit excellent light absorbing, semi conducting properties and hence are employed in a wide range of applications such as catalyst, biosensors, and in fuel cells. Green synthesis of nanoparticles using different microorganisms is widely accepted since this method is in expensive and eco-friendly. Nanoparticles synthesized by this route are smaller in size, highly stable, show high reactivity and stability. In this context, biofabrication of Silver Oxide Nanoparticles (SO-NP) by autolysate of Pseudomonas mendocina PM1 has been evaluated. Synthesis of SO-NP was observed, when autolysate of P. mendocina PM1 was incubated with 0.5 mM AgNO3 in dark for 24 h. Synthesis of SO-NP was confirmed by UV-Vis analysis. SO-NP was further confirmed by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) which confirmed presence of SO-NP. XRD revealed that SO-NP were of the type Ag3O4. FTIR analysis indicated that peptides were involved in the reduction and stability of SO-NP. SO-NP’s showed potent anti-microbial/ anti-biofilm activity against common pathogenic/non-pathogenic bacteria. This is the first report of synthesis of SO-NP by P. mendocina PM1. © 2021, National Institute of Science Communication and Information Resources. All rights reserved.
Biohydrogen production from microalgal sources
(Elsevier, 2025) Prabhakar Singh; Sakshi Singh; Pankaj Kumar Rai; Arvindkumar Kumar Singh
The global depletion of fossil fuel reserves and associated environmental challenges have shifted the focus to investigating alternative renewable energy sources. Microalgae have emerged as promising candidates for biohydrogen production due to their rapid growth and ability to thrive in diverse environmental conditions, including nonarable land, with unique photosynthetic capabilities and carbon dioxide assimilation strategies. Advancements in genetic and metabolic engineering have the potential to improve the photobiological production of hydrogen from microalgae significantly. This improvement involves manipulating specific enzymes, such as hydrogenase and nitrogenase, to modulate competing metabolic pathways to enhance hydrogen yields. The chapter provides a comprehensive overview of the current research on biohydrogen production from microalgae, with challenges and prospects in making it an economically viable approach. © 2025 Elsevier Inc. All rights reserved.
Catalyzing hydrogen production: Exploring plasmonic effects in self-assembled CuO/Cu2O thin films via pulsed laser deposition
(American Institute of Physics, 2024) Ashish K. Ranjan; Pardeep K. Jha; Priyanka A. Jha; Prabhakar Singh
Plasmonic catalysis triggers the dissociation of H 2 or adsorbed O 2 (sluggish processes) under continuous wave excitation via plasmon decay. This is coupled to interband or intraband excitation of d-band or sp-band, respectively, to levels above fermi level of metals. Here, we have studied the plasmonic and photocatalytic behavior in an environment friendly medium with AM 1.5 G sunlight of CuO/ Cu 2 O thin films fabricated by pulsed laser deposition technique in vacuum with varying thickness. We have achieved ∼ 0.59 kmol h − 1 g − 1 H 2 production in the CuO/ Cu 2 O film with a thickness of ∼ 27 nm. The role of plasmons with metal-dielectric and semiconductor-semiconductor interfaces is conducted through both experimental and theoretical approaches. The results suggest that the impact of plasmonic catalysis/synthesis is subject to the dimension, composition, and band alignment of two interface materials. © 2024 Author(s).
Compositional degradation with Br content in Cesium lead halide CsPbBrxI3-x
(Academic Press Inc., 2022) Manish Kumar; Vani Pawar; Pardeep K. Jha; Priyanka A. Jha; Prabhakar Singh
The inorganic cesium lead halide CsPbX3 (where X = I, Br, Cl) are reported to possess good stability than that of organic-inorganic hybrid halides. CsPbI3 is reported to have four phases: perovskite black phase (cubic (α), tetragonal (β), orthorhombic(γ)) and non-perovskite yellow orthorhombic (δ). With band gap of ∼ 1.73eV, CsPbI3-α is most suitable phase among all-inorganic lead halide Perovskites. However, in ambient atmosphere (almost instantly) the perovskite black phase convert into non-perovskite yellow orthorhombic phase. At the same time CsPbBr3 remains in the orthorhombic phase at room temperature. Thus, in the present investigation, compositional variation of Br in Cesium lead iodide CsPbBrxI3-x (x = 0.0 to 3.0 at the step of 0.5) samples synthesized by cold sintering technique is studied. The XRD patterns showed the orthorhombic phase for CsPbBr3. Further, CsPbBrxI3-x (x ≤ 1.0) have shown double phase corresponding to CsPbI3 (Pnma) + PbI2 ( R3¯m). However, the compound with 1.5 ≤ x < 3.0 showed the presence of various phases with and without oxygen including the CsPbBr3 (orthorhombic, Pnma) phase which has also been confirmed through UV–visible spectroscopy, impedance and Schottky anomaly. This compositional failure is also suggested by deviation from Vegards law showing volumetric expansion. The role of oxygen vacancy has been probed for the compositional failure for 1.5 ≤ x < 3.0 using XPS characterization and Raman spectroscopy. © 2022 Elsevier Inc.
DC conduction behaviour of niobium doped barium stannate
(2005) Prabhakar Singh; Om Parkash; Devendra Kumar
A few compositions with x ≤ 0.100 in the system BaSn1-x NbxO3 have been synthesized by solid-state ceramic method. All these are found to be single phase having cubic structure similar to BaSnO3. Electrical resistivity decreases with increasing niobium concentration up to x = 0.010 and thereafter it increases rapidly for the compositions with x = 0.050 and 0.100. This has been explained in terms of the change in charge compensation behaviour beyond x = 0.010. Measurement of Seebeck coefficient as a function of temperature shows that electrons are the majority charge carriers in compositions with x ≤ 0.010 while compositions with x > 0.010, exhibit p-type conductivity showing that holes are the majority charge carriers. © 2005 Springer Science + Business Media, Inc.
Dye sensitized solar cell based on poly(vinyl alcohol) doped with ammonium iodide solid polymer electrolyte
(National Institute of Optoelectronics, 2013) Vivek K. Singh; Annubhawi Annu; Upasana Singh; Prabhakar Singh; S.P. Pandey; Bhaskar Bhattacharya; Pramod K. Singh
A new polymer electrolyte Polyvinyl alcohol (PVA) doped with ammonium iodide (NH4I) have been developed, characterized and applied in Dye sensitized solar cell (DSSC). Polymer electrolyte shows enhancement in electrical conductivity by salt doping and then decrease after a certain composition. Infrared spectroscopy (IR) as well as x ray diffraction (XRD) affirmed composite nature of the polymer electrolyte. The polymer morphology has been studied using optical microscopy. Based on maximum conducting sample we have developed a DSSC which shows short circuit current density of 0.46 mA/cm2, open circuit voltage of 0.65 volt with overall conversion efficiency of 0.29 % at 1 sun condition.
Effect of Pb addition on dielectric relaxation in Se80In 20 glassy system
(Elsevier Ltd, 2013) Indra Sen Ram; Rajesh Kumar Singh; Prabhakar Singh; Kedar Singh
Dielectric properties of Se80In20 xPbx (x = 0, 5,10 and 15) chalcogenide glassy system are studied employing impedance spectroscopic technique in the frequency range 100 Hz-1 MHz and in the temperature range 313-383 K. It is found that the dielectric constant ε'and dielectric loss factor ε" both are dependent on frequency and temperature. The activation energy is also evaluated from the Arrhenius plot of the DC conductivity. All the above parameters show a reversal trends at 5 at wt.% of Pb. Also, anomalous behavior of ε' at low frequencies at all measured temperatures is observed for 15 at wt.% of Pb. This may be due to PbSe polaron formation, which is confirmed in Raman spectra of the investigated system. © 2012 Elsevier B.V. All rights reserved.
Effects of Salt Stress on Nutrient Cycle and Uptake of Crop Plants
(wiley, 2021) Lav Kumar Jaiswal; Prabhakar Singh; Rakesh Kumar Singh; Tanamyee Nayak; Yashoda Nandan Tripathi; Ram Sanmukh Upadhyay; Ankush Gupta
The biogeochemical cycling of elements involves the interactions between the biosphere and the surroundings in the form of cycling of elements throughout the different spheres viz., atmosphere, hydrosphere, and lithosphere. This chapter elucidates the effects of salinity stress on biogeochemical cycle and soil microorganisms that directly or indirectly affect the crop production. Nutrient uptake, primary productivity, and other biological processes are widely affected by nutrient limitation in terrestrial ecosystems. Nutrient cycling is one of the most important phenomena that occur in an ecosystem. The nutrient cycle represents the use, movement, and recycling of nutrients in the environment. Salt stress has an overall negative effect on carbon cycle which is implemented by its effect on various components of carbon cycle viz. photosynthesis, and microbial decomposers. Oxygen and water cycle or hydrological cycle are two biogeochemical cycles through which oxygen and water moves through biotic and abiotic components of earth and are essential for survival of life. © 2022 John Wiley & Sons Ltd. All rights reserved.
Electrical conduction mechanism in Se90-xTe5Sn5Inx (x = 0, 3, 6 and 9) multi-component glassy alloys
(American Institute of Physics Inc., 2015) Indra Sen Ram; Sunil Kumar; Rajesh Kumar Singh; Prabhakar Singh; Kedar Singh
Electrical conductivity of Se90-xTe5Sn5Inx (x = 0, 3, 6 and 9) glassy systems was studied employing impedance spectroscopic technique in the frequency range 100 Hz to 1 MHz and in the temperature range 308-388 K. The DC conductivity (σdc) at each temperature was evaluated from the low frequency plateau region for all the samples under investigation. The bulk conductivity for each sample was also evaluated from Nyquist impedance plots. The semicircle shape of Nyquist plot exhibit dipolar nature of samples. The activation energy for glassy, amorphous and crystalline region from the Arrhenius plot of the DC conductivity and bulk conductivity was evaluated. From the results it is found that activation energy varied from 0.091 to 0.194 eV in glassy, 0.686 to 0.002 eV in amorphous and 0.215 to 0.503 eV in crystalline region. The activation energy (ΔE) from DC conductivity and bulk conductivity found to be close in corresponding regions. The pre-exponential factor was also calculated for all three regions. © 2015 Author(s).