Browsing by Author "Kumar, Vijay"

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    Facile synthesis and characterization of hydroxyapatite particles for high value nanocomposites and biomaterials
    (Elsevier, 2017-06-07) Miculescu, Florin; Mocanu, Aura-Cătălina; Dascălu, Cătălina Andreea; Maidaniuc, Andreea; Batalu, Dan; Berbecaru, Andrei; Voicu, Stefan Ioan; Miculescu, Marian; Kumar, Vijay; Ciocan, Lucian Toma
    Lately Hydroxyapatite has gained a lot of research interest and intense focus due to its structural as well as compositional similarity to the components of human bone mineral. The conversion of calcium-rich precursors to hydroxyapatite could lead to the development of a new sustainable alternative with a valuable environmental and socio-economically impact. Still, current approaches faces lots of challenges in terms of synthesis parameters compatible to a reproducible route for calcium phosphates (hydroxyapatite included) synthesis. The optimization of Rathje synthesis route and characterization of biogenic derived calcium phosphates from dolomitic marble and Mytilus galloprovincialis seashells, constitutes the main goals of this study. The synthesized materials were characterized using FTIR, SEM coupled with EDS, and X-ray diffraction at all synthesis stages. Precursors were also subjected to thermal analysis and differential scanning calorimetry for thermal transformations investigations and dissociation temperature setting. This study suggests that acid quantity and magnetic stirring are the key-factors for Ca/P molar ratio adjustment, hence for the amount of naturally-derived hydroxyapatite. This research also contributes to the development of new strategies for further optimization of the conversion procedure and removal of residual components.
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    Kinetic study of the biodegradation of acephate by indigenous soil bacterial isolates in the presence of humic acid and metal ions
    (MDPI, 2020-03-11) Singh, Simranjeet; Kumar, Vijay; Singla, Sourav; Sharma, Minaxi; Singh, Dhananjaya P.; Prasad, Ram; Thakur, Vijay Kumar; Singh, Joginder
    Many bacteria have the potential to use specific pesticides as a source of carbon, phosphorous, nitrogen and sulphur. Acephate degradation by microbes is considered to be a safe and effective method. The overall aim of the present study was to identify acephate biodegrading microorganisms and to investigate the degradation rates of acephate under the stress of humic acid and most common metal ions Fe(III) and copper Cu(II). Pseudomonas azotoformanss strain ACP1, Pseudomonas aeruginosa strain ACP2, and Pseudomonas putida ACP3 were isolated from acephate contaminated soils. Acephate of concentration 100 ppm was incubated with separate strain inoculums and periodic samples were drawn for UV—visible, FTIR (Fourier-transform infrared spectroscopy) and MS (Mass Spectrometry) analysis. Methamidophos, S-methyl O-hydrogen phosphorothioamidate, phosphenothioic S-acid, and phosphenamide were the major metabolites formed during the degradation of acephate. The rate of degradation was applied using pseudo-first-order kinetics to calculate the half-life (t1/2) values, which were 14.33–16.72 d−1 (strain(s) + acephate), 18.81–21.50 d−1 (strain(s) + acephate + Cu(II)), 20.06 –23.15 d−1 (strain(s) + acephate + Fe(II)), and 15.05–17.70 d−1 (strains + acephate + HA). The biodegradation efficiency of the three bacterial strains can be ordered as P. aeruginosa > P. putida > P. azotoformans. The present study illustrated the decomposition mechanism of acephate under different conditions, and the same may be applied to the removal of other xenobiotic compounds
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    Recent progress in cellulose nanocrystals: sources and production
    (Royal Society of Chemistry, 2017-01-24) Trache, D.; Hussin, M. H.; Haafiz, M. M.; Kumar, Vijay
    Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.
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    Recent progress in gelatin hydrogel nanocomposites for water purification and beyond
    (Elsevier, 2017-05-31) Thakur, Sourbh; Govender, Penny P.; Mamo, Messai A.; Tamulevicius, Sigitas; Kumar, Vijay
    Innovative characteristics of hydrogels such as swellability, modifiability and hydrophilicity make them materials of choice for water treatment and other applications. Hydrogels have shown excellent adsorptive performance for different types of water pollutants comprising toxic dyes, nutrients and heavy metals. Among different types of hydrogel based materials, hydrogel-nanomaterials combination represent a highly viable method to further improve the properties of hydrogel for numerous applications. The combination of hydrogel and nanomaterials leads to the development of hybrid hydrogel with multifunctional network. This novel combination gives synergistic effect to the newly formed novel hydrogel materials. In this article, we briefly review the recent progress in gelatin based hydrogel nanocomposites with particular emphasis on wastewater treatment along with biomedical applications.
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    A study on the thermodynamic changes in the mixture of polypropylene (PP) with varying contents of technological and post-user recyclates for sustainable nanocomposites
    (Elsevier, 2017-05-25) Michalska-Pożoga, Iwona; Rydzkowski, Tomasz; Mazur, Piotr; Sadowska, Olga; Kumar, Vijay
    The use of recycled materials can address some of the issues associated with the cost and environmental implications of non-renewable materials. So the prime aim of this work was to determine the thermodynamic changes in the polypropylene (PP) mixtures depending on the percentage amount of different origin recyclates for sustainable nanocomposites. In this study, different polypropylene mixtures with the addition of PP recyclates from a selective waste collection system and in-plant recycling system have been subjected to detailed analysis. It was obvious that recyclates from technological waste were of higher quality than post-user recyclates obtained from a selective waste collection system. The influence of the source of the recyclates on the different properties of the processed materials has been studied in detail. The content of the repeatedly processed material in the technological recyclates was found to explain the unexpected influence of the recyclates content on the properties of the final product. A mathematical model was also formulated to calculate the content of the material with certain amount of recirculations in the in-plant recycling system since no analyses concerning the content of the repeatedly processed material in the technological recyclates added to the original material were found in the literature.
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    Synthesis and characterization of cellulose acetate-hydroxyapatite micro and nano composites membranes for water purification and biomedical applications
    (Elsevier, 2017-05-06) Pandele, A. M.; Comanici, F. E.; Carp, C. A.; Miculescu, F.; Voicu, S. I.; Kumar, Vijay; Serban, B. C.
    In this work, we report facile synthesis and characterization of new cellulose acetate-hydroxyapatite membranes for water purification and biomedical applications. The membranes were synthesized from a polymer solution in N, N’-dimethylformamide (12% wt.) where different concentrations of hydroxyapatite (1, 2, 4% wt. based on the amount of polymer) were dispersed using sonication. The synthesis of membranes was carried out by precipitation employing phase inversion using deionized water. The morphological and structural characterization of the synthesized membranes was carried out using SEM, EDS and FT-IR. Thermal characterization (TGA & DTG) and water flows analysis of the synthesized membranes was also carried out. The SEM analysis confirmed the presence of hydroxyapatite micro/nanostructured particles in the membrane as well as significant changes in the morphology of the membranes surface. The presence of inorganic compounds was also found to influence the thermal or hydrodynamic properties of the composite membranes, leading to a more stable hydrodynamic behavior, flow variation in time being much lower compared to the control membrane of cellulose acetate.
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    Synthesis, characterization, and functionalization of zirconium tungstate (ZrW2O8) nano‐rods for advanced polymer nanocomposites
    (Wiley: 12 months, 2017-02-21) Kumar, Vijay; Li, Y.; Wu, H.; Kessler, M. R.
    Nanomaterials based on zirconium tungstate (ZrW2O8) exhibit numerous outstanding properties that make them ideal candidates for the development of high-performance composites. Low coefficient of thermal expansion for advanced materials is a promising direction in the field of insulating nanocomposites. However, the agglomeration of zirconium tungstate (ZrW2O8)-based nanomaterials in the polymer matrix is a limiting factor in their successful applications, and studies on surface functionalization ZrW2O8 for advanced nanocomposites are very limited. In this work, ZrW2O8 nano-rods were synthesized using a hydrothermal method and subsequently functionalized in a solvent-free aqueous medium using dopamine. Both pristine and functionalized nano-rods were thoroughly characterized using Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction, Scanning Electron Microscopy (SEM), and transmission electron microscopy techniques, which confirmed the successful functionalization of the nanomaterials. Polymer nanocomposites were also prepared using epoxy resin as a model matrix. Polymer nanocomposites with functionalized ZrW2O8 nano-rods exhibited low coefficient of thermal expansion and enhanced tensile properties. The improved properties of the nanocomposites render them suitable for electronic applications.
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    Towards sustainable micro and nano composites from fly ash and natural fibers for multifunctional applications
    (Elsevier, 2017-05-24) Pappu, Asokan; Kumar, Vijay
    Manufacturing of petroleum based synthetic materials, exploitation of timber products from forest reserves, improper management of industrial wastes and natural resources greatly persuade the environmental contaminations and global warming. To find viable solutions and reduce such alarming issues, innovative research work on recycling of unutilized materials such as fly ash and natural cellulosic polymers has been reported in this work to develop advanced sustainable hybrid micro/nano composites. In this study, the use of natural cellulosic sisal fibers with fly ash has enhanced the tensile properties and surface finish of composites. Fly ash particulates acted as fillers, additives, as well as surface-finishing medium and sisal fibers as reinforcing elements in achieving glossy finish sustainable composites. The developed composites have been found to be stronger than wood, plastics and have many opportunities for multifunctional applications.
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    Ultra-thin electrospun nano-fibres for damage tolerant composite laminates
    (Cranfield University, 2019-11-08 12:34) An, Donglan; Lotfian, Saeid; Mesbah, Daria; Ayre, David; Yoosefinejad, Ata; Kumar, Vijay; Yazdani Nezhad, Hamed
    Raw data and calculation of Mode-I fracture toughness at initiation and propagation for different densities of electrospun nanofibres embedded for toughening of composite laminates
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    Underpinning Data for Article: Carbon nanotube embedded adhesives for real-time monitoring of adhesion failure in high performance adhesively bonded joints
    (Cranfield University, 2020-09-25 19:16) Yazdani Nezhad, Hamed; Bregar, Tadej; An, Donglan; Gharavian, Somayeh; Burda, Marek; Durazo-Cardenas, Isidro; Kumar, Vijay; Ayre, David; Sloma, Marcin; Hardiman, Mark; McCarthy, Conor
    The underpinning data for Research Article on Carbon nanotube embedded adhesives for real-time monitoring of adhesion failure in high performance adhesively bonded joints