Browsing by Author "Manoj Kumar Tripathi"

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Bioremediation of pesticides residues: A psychological approach
(Nova Science Publishers, Inc., 2018) Savita Singh; Ashutosh Kumar; S. P. Jeevan Kumar; Mohd Imran; Madan Kumar; Arvind Nath Singh; Manoj Kumar Tripathi
To increase the food production, pesticides have been used excessively; as a result, they have become a threat to the environment. In the present era, microbial degradation is one of the important techniques for degradation of pesticides from agricultural lands. Studies have been conducted on the use of different microbes such as bacteria, fungi and genetically modified microorganisms for degradation of pesticides. Case studies and researches have revealed that microbial consortia of naturally occurring microbes isolated from particular contaminated environments have potential to degrade pesticides at faster rate rather than individual microbes. Microalgae and cyanobacteria exhibiting high growth rate and biodegradation potential are yet to be explored. Microalgae and cyanobacteria are cosmopolitan in nature ranging from unicellular to filamentous forms that inhabit several environmental conditions. In order to re-evaluate the current scenario of pesticide contamination and the role of micro algae and cyanobacteria have been discussed. The chapter highlights the use of microalgae and cyanobacteria in bioremediation of pesticide contamination and remedies using psychological approaches. © 2018 by Nova Science Publishers, Inc. All rights reserved.
Cyanobacteria, Lyngbya aestuarii and Aphanothece bullosa as antifungal and antileishmanial drug resources
(Asian Pacific Tropical Biomedicine Press, 2013) Maheep Kumar; Manoj Kumar Tripathi; Akanksha Srivastava; Jalaj Kumar Gour; Rakesh Kumar Singh; Ragini Tilak; Ravi Kumar Asthana
Objective: To investigate two cyanobacteria isolated from different origins i.e. Lyngbya aestuarii (L. aestuarii) from brackish water and Aphanothece bullosa (A. bullosa) from fresh water paddy fields for antifungal and antileishmanila activity taking Candida albicans and Leishmania donovain as targets. Methods: Biomass of L. aestuarii and A. bullosa were harvested after 40 and 60 d respectively and lyophilized twice in methanol (100%) and redissolved in methanol (5%) for bioassay. Antifungal bioassay was done by agar well diffusion method while antileishmanial, by counting cell numbers and flageller motility observation of promastigotes and amastigotes from L. donovani. Fluconazole and 5% methanol were used as control. Results: Both the cyanobacteria were found to be potent source of antifungal activity keeping fluconazole as positive control, however, methanolic crude extract (15 mg/mL) of A. bullosa was found more potent (larger inhibition zone) over that of methanolic crude extract of L. aestuarii. Similarly antileishmanial activity of crude extract (24.0 mg/mL) of A. bullosa was superior over that of methanolic crude extract of L. aestuarii (25.6 mg/mL). Conclusions: Antifungal and antileishmanial drugs are still limited in the market. Screening of microbes possessing antifungal and antileishmanial activity drug is of prime importance. Cyanobacteria are little explored in this context because most of the drugs in human therapy are derived from microorganisms, mainly bacterial, fungal and actinomycetes. Thus in the present study two cyanobacterial strains from different origins showed potent source of antifungal and antileishmanial biomolecules. © 2013 Asian Pacific Tropical Biomedical Magazine.
Electrodeposition of Ni-Fe/Bn nano-composite coatings from a non-aqueous bath and their characterization
(Electrochemical Science Group, 2013) Manoj Kumar Tripathi; D.K. Singh; V.B. Singh
Ni-Fe alloy matrix nano-composite coatings containing uniformly dispersed 24 wt% BN (boron nitride) particles (micron-sized) were electrolytically codeposited under direct current condition from a non-aqueous sulfamate-ferrous sulphate-dimethylformamide bath. Effect of various deposition parameters like Fe++ ion concentration, current density, temperature, stirring rate, etc. on the composition and properties of the electrodeposits was studied and optimum condition for maximum incorporation of BN particles was determined. The composite coatings thus obtained were characterized by XRD, SEM, EDAX, DSC and spectrophotometric analyses. The iron content in the alloy deposits varied between 7-25 wt%. The deposition of alloy matrix showed anomalous behaviour and was found under charge transfer and diffusion control. The calculated crystallite size of the composite deposits was found between 4-13 nm while the calculated strain in the composite coatings ranged 0.017-0.02. All the composite coatings showed fcc structure with preferred orientation in <111> crystallographic direction. The lattice parameter of the composite coatings was found to be slightly larger than that of pure nickel. Hardness of as deposited and heat treated nano-composite coatings was found to be significantly higher than that of the parent Ni-Fe alloy. A correlation between crystallite size and strain with hardness has been worked out. The hydrogen content analysis of the composites showed almost minimal hydrogen inclusion (~ 1-2 ppm) in the deposits. © 2013 by ESG.
Electrodeposition of Nickel-molybdenum alloys
(Nova Science Publishers, Inc., 2014) Manoj Kumar Tripathi; V.B. Singh
The properties of molybdenum (Mo) are attractive and the coatings of the metal can find tremendous uses. The favourable mechanical properties, particularly those at elevated temperatures, may not be exploited to useful ends by the coatings, but its high corrosion resistance can be of considerable value for protective and other purposes. The deposition of Mo has not been successful either from aqueous or organic solutions; and that from fused salt bath requires complete exclusion of air and moisture, which makes the process very tedious at high temperatures. However, deposition of its alloys containing iron-group metals (nickel, cobalt or iron) has got considerable success in the past. These alloys possess the properties to meet the desired structural strength in various applications. Nickel-molybdenum (Ni-Mo) alloys are more preferable compared to other Mo alloys from applications point of view. Electrodeposition is known to be the most convenient, economic and green process to obtain the metals and alloys in various forms (thin films, coatings, electroformed and other desired shapes, etc.). Therefore, comprehensive information is desirable in this direction concerning Ni-Mo alloys. The electrochemical aspects of Mo, difficulties in its electrolytic reduction and development of baths for electrodeposition of Ni-Mo alloys, along with the latest literature review are covered in this chapter. Mechanism of alloy deposition and influence of various operating variables on this have been discussed. The structure and different physical, mechanical properties of the alloys have also been incorporated. Future prospects of the deposition of Ni-Mo alloys and possible ternary/quaternary alloys using non-aqueous baths have also been mentioned. © 2014 by Nova Science Publishers, Inc. All rights reserved.
Electrolytic Preparation of Ni-B4C Composite Coating and its Characterization
(Springer Science and Business Media, LLC, 2015) Dhananjay Kumar Singh; Manoj Kumar Tripathi; V.B. Singh
Ni-B4C composite coatings with various contents of B4C particles were electrodeposited from a nickel acetate containing suspended B4C (<10 µm) particles using N-methylformamide as solvent. Plating variables including current density, B4C concentration in the bath, temperature, and stirring rate were optimized for the highest amount of the B4C codeposition. The deposit’s microstructure and composition were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray analysis. In order to check the suitability of solvent for obtaining satisfactory deposits free from hydrogen (i.e., inevitable in aqueous media due to hydrogen-evolution reaction), the hydrogen content of the composite was also determined. Effects of B4C incorporation and annealing of the composite on microhardness have also been investigated. Composite coatings of superior hardness with minimum strain and hydrogen content were obtained. © 2015, ASM International.
Microstructure and properties of electrochemically deposited Ni-Fe/Si3N4 nanocomposites from a DMF bath
(Electrochemical Society Inc., 2015) Manoj Kumar Tripathi; Dhananjay Kumar Singh; V.B. Singh
This paper deals with successful co-deposition of Ni-Fe/Si3N4 nanocomposites applying various current densities (0.5-3.0 A dm-2) from a sulfamate-DMF (N,N-dimethylformamide) bath containing different concentration of Si3N4 nanoparticles. The nanocomposits have been characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and Energy Dispersive X-ray Analysis. The microhardness, magnetic and electrical properties along with thermal stability has been evaluated. A maximum of 13.6 wt% Si3N4 particles is incorporated in the metallic matrix from 10 g/L bath load of the ceramic particles. The matrix has face-centred-cubic structure. The crystallite size of the nanocomposites is found in the range of 8-13 nm while the strain values ranged between 0.0081 and 0.01. The magnetic measurement reveals superparamagnetic character of the coatings. Occlusion of nano-Si3N4 renders superior hardness to the matrix metal. The hydrogen content in the coatings is minimal, i.e. nearly 6 ppm, which does not cause any adverse effect on the micro- and crystallographic structure of the composites. © 2014 The Electrochemical Society.
Microstructure and properties of Si3N4 and TiN nano-particles reinforced electrodeposited functional Ni-Fe matrix nanocomposite
(Electrochemical Society Inc., 2016) Manoj Kumar Tripathi; V.B. Singh
Functional Ni-Fe/Si3N4-TiN nanocomposite coatings were electro-codeposited from sulphamate-N,N-dimethylformamide bath containing dispersed Si3N4 and TiN nano-particles 10 g/L each. The effect of current density on the incorporation of the ceramic particulate and on the properties of the deposits was investigated. The deposited coatings were characterized using various advanced techniques such as scanning electron microscopy, X-ray diffractometry, transmission electron microscopy and atomic force microscopy. Physical properties such as microhardness, corrosion resistance and magnetic property of the composite were evaluated. Results indicated that Si3N4 and TiN both the ceramics has prodigious effect on the microstructure and properties of the coating. Ni-Fe/Si3N4-TiN coatings showed higher hardness in comparison with the Ni-Fe, Ni-Fe/Si3N4 and Ni-Fe/TiN coatings. Hardness values of the coatings ranged from 650 HV to 773 HV and the coating with maximum hardness was obtained at current density 3.0 A dm-2. Further, significant influence had been observed on corrosion resistance by the ceramic particles. Magnetic investigations revealed characteristic superparamagnetic behavior of the coatings. © 2016 The Electrochemical Society.
Preparation of Ni-TiC Nanocomposites by Electrolytic Codeposition from a Non Aqueous Bath and Their Characterization
(2012) Dhananjay Kumar Singh; Manoj Kumar Tripathi; Vijai Bahadur Singh
Nickel-titanium carbide (Ni-TiC) nanocomposite coatings were prepared under direct current conditions by codeposition of nano titanium carbide (TiC) particles (<200 nm) and nickel from a nickel acetate bath using N-methylformamide as a non aqueous solvent. Influence of current density, concentration of TiC particles, agitation and temperature of bath was investigated and the optimum values of these parameters for reaching maximum weight% incorporation of TiC particles in the coating were determined. Coatings morphology and chemical composition were characterized by SEM and EDAX analysis. Crystallographic structures and microhardness were investigated. Also it is seen that the existence of second ceramic phase in the co-deposited layer reduces the average crystallite size of Ni-matrix to 11.5 nm and the composite possessed fcc lattice. © 2012, The Electrochemical Society, Inc. All rights reserved.
Properties of electrodeposited functional Ni–Fe/AlN nanocomposite coatings
(Elsevier B.V., 2019) Manoj Kumar Tripathi; V.B. Singh
Ni–Fe/AlN nanocomposite coatings were electrodeposited from sulphamate based electrolyte in N,N-dimethylformamide solvent. The conditions of maximum particulate incorporation into the matrix were optimized. The coatings were characterized by Scanning electron microscopy (SEM), Energy dispersive analysis of X-ray (EDAX), X-ray diffractometry (XRD), and Vicker's microhardness tester. The reinforcement of matrix with nano-AlN rendered superior microhardness (up to 560 HV) to the nanocomposites over monolithic Ni and Ni–Fe alloy deposits. Incorporation of aluminium nitride (AlN) particles in the Ni–Fe alloy matrix under optimum condition was recorded up to 23.2 wt%. Magnetic measurements revealed soft ferromagnetic behaviour of the deposit with marked tendency towards superparamagnetism. © 2015 The Authors
Structure and properties of electrodeposited functional Ni-Fe/TiN nanocomposite coatings
(Elsevier B.V., 2015) Manoj Kumar Tripathi; V.B. Singh; H.K. Singh
Ni-Fe/TiN nanocomposite coatings were successfully prepared by cathodic co-deposition using nickel sulfamate, ferrous sulphate and N,N-dimethylformamide. The influence of the applied current density on the chemical composition, morphology, crystallography, hardness and electrical property of the coatings was investigated. A maximum of 18.73wt.% TiN particles was incorporated in the Ni-Fe alloy matrix at 3.0Adm-2 and 45°C from a bath containing 5g/L of TiN particle suspension. The TiN particles were distributed uniformly in the matrix phase with little agglomeration. The TiN nanoparticles once incorporated in the composite coating promoted the nucleation of the matrix grains. The incorporation of TiN nanoparticles in the Ni-Fe alloy matrix caused a distinct microstructural change from uniform granular in Ni-Fe alloy to 'cauliflower-like' morphology in Ni-Fe/TiN nanocomposites. Face-centered-cubic crystals of both the ceramic particles and the nanocomposite coatings were observed. The crystallite size and the microstrain of the composites were found below 15nm and <0.0085, respectively. An improvement in the microhardness of the composites over the electrodeposited Ni and Ni-Fe alloy was recorded. Heat treatment led to slight grain growth and decrease in microhardness. The deposits have shown ferromagnetic characteristic. © 2015 Elsevier B.V.