Browsing by Author "Dhananjay Kumar Singh"

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Advancements in non-thermal technologies for enhanced extraction of functional triacylglycerols from microalgal biomass: A comprehensive review
(Elsevier Ltd, 2024) Harsh B. Jadhav; Pintu Choudhary; Nikhil D. Deshmukh; Dhananjay Kumar Singh; Moumita Das; Arpita Das; Nadiminti Chandana Sri Sai; Gayathri Muthusamy; Uday S. Annapure; Seema Ramniwas; Robert Mugabi; Gulzar Ahmad Nayik
Microalgae have emerged as a storehouse of biologically active components having numerous health benefits that can be used in the formulation of nutraceuticals, and functional foods, for human consumption. Among these biologically active components, functional triacylglycerols are increasingly attracting the attention of researchers owing to their beneficial characteristics. Microalgae are excellent sources of triacylglycerol containing omega-3 and omega-6 fatty acids and can be used by the vegan population as a replacement for fish oil. The functional triacylglycerols extracted using conventional processes have various drawbacks resulting in lower yield and inferior quality products. The non-thermal technologies are emerging as user-friendly and environment-friendly technologies that intensify the yield of final products and maintain the high purity of extracted products that can be used in food, cosmetic, pharmaceutical, and nutraceutical applications. The present review focuses on major non-thermal technologies that can probably be used for the extraction of high-quality functional triacylglycerols from microalgae. © 2024 The Author(s)
Electrodeposition and characterization of Ni-TiC composite using N-methylformamide bath
(Elsevier Ltd, 2012) Dhananjay Kumar Singh; V.B. Singh
Ni-TiC composite coatings containing a maximum of 14.62wt.% TiC were obtained under optimum condition by the constant current electrodeposition of Ni and micrometer sized particles of TiC powder onto the surface of commercial grade copper substrates. A bath containing 200g/l nickel acetate, 35g/l boric acid and 40g/l TiC in N-methylformamide at current density 2Adm-2, duration of electrolysis 30min and bath temperature 60°C was found to be optimum condition for electrodeposition. The composition, microstructure, hydrogen content and microhardness were investigated by AAS, EDAX, SEM, XRD and microhardness tester. The single line broadening analysis of peak shows that crystallite size decreases with increase in current density. The hydrogen content in the deposits was found to be minimal. The effect of annealing temperature on microstructure and microhardness was also examined. © 2011 Elsevier B.V.
Electrodeposition of Ni-SiC composite from a non-aqueous bath
(2011) Dhananjay Kumar Singh; V.B. Singh
Electrodeposited Ni-SiC composite deposits with 10.5 wt % SiC were produced on copper substrate using a non-aqueous organic solvent. N-Methylformamide was found to be the most suitable solvent as it has a high dielectric constant (182) that allows high tolerance of the electrolyte in the bath, which is ordinarily not obtained in other solvents. The optimum condition arrived for deposition was nickel acetate 200 g/l, boric acid 35 g/l, SiC 10 g/l, current density 2.0 A dm-2, duration of electrolysis 30 min, and bath temperature 60°C. Satisfactory bright composite deposits were obtained, which were quite adherent to the copper base. Scanning electron microscope, energy-dispersive analysis by x ray, and X-ray diffraction studies have been performed to characterize the composites. Effect of current density on composition and microhardness of the composite deposits was investigated. Also, the effect of annealing on the microhardness of the deposits was studied. © 2010 The Electrochemical Society.
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.
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.
Structure, mechanical and magnetic properties of Al4C3 reinforced nickel matrix nanocomposites
(Institute of Physics Publishing, 2018) Alok Kumar Chaudhari; Dhananjay Kumar Singh; V.B. Singh
A new type of nanocomposite, Ni-Al4C3 was prepared using Al4C3 as reinforcement by cathodic co-deposition at different current densities (1.0 to 5.0 A dm-2) from a nickel acetate-N-methyl formamide (non-aqueous) bath. Influence of current density and incorporation of Al4C3 particles in nickel matrix on the structure and properties of the composite coatings was investigated. Surface morphology and composition of the deposits were determined by SEM and EDAX. Crystallographic structure and orientation of the electrodeposited Ni-Al4C3 composite were studied by x-ray diffraction. Compared to nickel metal, these nanocomposites exhibited finer grains, higher microhardness, improved corrosion resistance and enhanced soft magnetic properties. Composite deposited at higher current densities (>2 A dm-2) shows mild texturing along (200) plane. The effect of heat treatment on the microstructure, texture and microhardness of the nanocomposites was also investigated. © 2018 IOP Publishing Ltd.