Browsing by Author "Rakesh Kumar Gautam"

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A Study on Mechanical Properties and Strengthening echanisms of AA5052/ZrB2 in Situ Composites
(American Society of Mechanical Engineers (ASME), 2017) Narendra Kumar; Gaurav Gautam; Rakesh Kumar Gautam; Anita Mohan; Sunil Mohan
In the present study, in situ reaction technique has been employed to prepare AA5052 matrix composites reinforced with different vol. % of ZrB2 particles (i.e., 0, 4.5, and 9 vol. %). Composites have been characterized by X-ray diffraction (XRD) to confirm the in situ formation of ZrB2 particles in the matrix. Optical Microscopy (OM) studies reveal the refinement of aluminum-rich phase due to the presence of ZrB2 particles. Scanning electron microscopy (SEM) studies reveal size and distribution of ZrB2 particles while transmission electron microscopy (TEM) reveals the presence of dislocations in the matrix around ZrB2 particles. Hardness and tensile testing of composites have been carried out at room temperature to evaluate the mechanical properties. The results reveal the improvement in hardness and strength with increased amount of ZrB2 particles. Strength of AA5052/ZrB2 in situ composites has been analyzed by various strengthening mechanism models. The analysis revealed that Orowan and Solid solution strengthening mechanisms are the predominant mechanism for high strength composites. Theoretical yield strength is about 6-10% higher than the experimental values due to clustering tendency of ZrB2 particles. © Copyright VC 2017 by ASME.
Characterisation of Rapid Microwave-Sintered Mg/MgO Composite
(Springer, 2023) Asgar Shakil; Rakesh Kumar Gautam; Uppu Srinivas Rao
Magnesium metal matrix composites are now been used in large number of structural applications. An attempt is made to synthesise pure Mg and Mg/5 wt% MgO (~ 10 µm) composite through powder metallurgy route assisted by rapid microwave sintering. The microwave sintering temperatures are varied at 450 °C, 500 °C and 550 °C, and different mechanical and physical characterisations of the composites are studied. The composites show improved properties with the addition of magnesium oxide as reinforcement. XRD investigations show that no reaction has taken place between magnesium and magnesium oxide at all sintering temperatures. At higher sintering temperature, few magnesium particles oxidise to form MgO. Microstructure shows well-distributed MgO particles in magnesium matrix. The addition of 5 wt% hard MgO particles improve hardness and increase 0.2% compressive yield strength (CYS) and ultimate compressive strength (UCS) than pure magnesium at all sintering temperatures. © 2022, The Indian Institute of Metals - IIM.
Coating Methods for Hydroxyapatite—A Bioceramic Material
(Springer Nature, 2023) Gagan Bansal; Rakesh Kumar Gautam; Joy Prakash Misra; Abhilasha Mishra
Hydroxyapatite (HAP), an apatite of calcium phosphate with the chemical formula (Ca 10 (PO4) 6(OH) 2) is one of the most valuable bioceramic materials with excellent bone-type composition. It is the best-suited material for orthopedic artificial human implants. Due to its high level of feasible characteristics like biocompatibility, osteointegration, non-toxicity, cytocompatibility, high thermal stability, anti-fungal and antibacterial etc., it is being highly researched for optimized composition based on applications. HAP as a coating material on biomedical substrates is effective for material upgradation. Enhancement in the surface morphology and characteristics of advanced biocomposite materials can be accomplished using a coating of HAP with different commercial methods including sol–gel, dip coating, spin coating, thermal spray, pulsed deposition, sputter, electrophoretic deposition, thermal, biomimetic, microarc oxidation and the combination of two or more coating methods. Various thin film deposition techniques like solution-based deposition technique, vapors-based deposition technique (VDT) and physical vapors deposition techniques are employed as and when desired based on applications and requirements. Further, Solution-based deposition techniques includes sol–gel coating, spin coating, dip coating, screen coating and combined coating technique. Vapor-based deposition technique includes metal–organic, low-pressure, atmospheric pressure and plasma-enhanced VDT. Physical vapor deposition techniques include thermal evaporation, pulsed laser deposition, molecular beam and sputtering deposition. The current chapter outlines various coating methods used for coating hydroxyapatite material on polymer, ceramic, metallic, non-metallic, alloy and composite material substrates. Also, applications of HAP and its coating in the biomedical field are briefly discussed. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Dry Sliding Wear Behavior of Chemically Treated Sisal Fiber Reinforced Epoxy Composites
(Taylor and Francis Ltd., 2022) Sudhakar Behera; Rakesh Kumar Gautam; Sunil Mohan; Arghya Chattopadhyay
The effect of fiber surface treatment on the structural, thermal, and tribological properties of sisal fibers and their epoxy composites were investigated in this research work. Sisal fibers were modified with alkali (NaOH), glutamic acid, and a combination of both alkali and glutamic acid. To analyze the effect of chemical modification on the properties of sisal fibers, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and thermogravimetric analysis (TGA) were performed. It is observed from the experimental results that there is an improvement in the surface roughness, crystallinity, and thermal stability of chemically treated fibers in comparison to untreated fibers. Microhardness properties of chemically treated sisal fiber reinforced epoxy composites (SFREC) also showed minor improvement. The dry sliding wear experiments were carried out according to Taguchi design of experiment (DOE) methods. The results of the wear test showed an increase in the wear resistance of chemically modified SFREC relative to untreated SFREC. The best wear properties were demonstrated by alkali treated SFREC. It is also observed from the findings of ANOVA that the applied load and sliding distance have the most defining effect on wear volume loss of SFREC. © 2021 Taylor & Francis.
Enhanced mechanical properties of hBN-ZrO2 composites and their biological activities on: Drosophila melanogaster: Synthesis and characterization
(Royal Society of Chemistry, 2019) Amarendra Gautam; Chandkiram Gautam; Monalisa Mishra; Vijay Kumar Mishra; Ajaz Hussain; Swetapadma Sahu; Reetuparna Nanda; Bikash Kisan; Santoshkumar Biradar; Rakesh Kumar Gautam
In this study, six compositions in the system [x(h-BN)-(100 - x)ZrO2] (10 ≤ x ≤ 90) were synthesized by a bottom up approach, i.e., the solid-state reaction technique. XRD results showed the formation of a novel and main phase of zirconium oxynitrate ZrO(NO3)2 and SEM exhibited mixed morphology of layered and stacked h-BN nanosheets with ZrO2 grains. The composite sample 10 wt% h-BN + 90 wt% ZrO2 (10B90Z) showed outstanding mechanical properties for different parameters, i.e., density (3.12 g cm-3), Young's modulus (10.10 GPa), toughness (2.56 MJ m-3), and maximum mechanical strength (227.33 MPa). The current study further checked the in vivo toxicity of composite 10B90Z and composite 90B10Z using Drosophila melanogaster. The composite 10B90Z showed less cytotoxicity in this model, while the composite 90B10Z showed higher toxicity in terms of organ development as well as internal damage of the gut mostly at the lower concentrations of 1, 10, and 25 μg mL-1. Altogether, the current study proposes the composite 10B90Z as an ideal compound for applications in biomedical research. This composite 10B90Z displays remarkable mechanical and biological performances, due to which we recommend this composition for various biomedical applications. © ??? The Royal Society of Chemistry.
Enhanced physical and mechanical properties of resin added with aluminum oxyhydroxide for dental applications
(Elsevier Ltd, 2023) Savita Kumari; Ajaz Hussain; Sarvesh Kumar Avinashi; Rajat Kumar Mishra; Jitendra Rao; Sudhakar Behera; Rakesh Kumar Gautam; Chandkiram Gautam
Resin has limited applications however, its composites with metal oxides exhibited improved characteristics for numerous applications such as dental restoration, dentures etc. Herein, various compositions were fabricated by substituted aluminum oxyhydroxide (AlOOH) into resin via a scalable heat cure process. For phase identification and structural study, XRD and FT-IR techniques were employed. As increasing the content of AlOOH into the PZ {Poly (methyl-methacrylate)-zirconia, (PMMA-ZrO2)} matrix, the percentage of crystallinity and the crystallite size were also estimated and varied from 14.8 to 18.4 and 1.48 nm–1.82 nm respectively. Moreover, to reveal the surface morphology, optical and mechanical behaviour of fabricated nano-composites, the SEM, UV–Vis and Universal testing machine (UTM) were also performed. The direct, indirect band gap, urbach energy of the fabricated composites were noticed within the range of 5.14 ± 0.005–5.19 ± 0.005 eV, 5.31 ± 0.005–5.35 ± 0.005 eV, and 189 ± 3.78–69.6 ± 1.39 eV respectively. The skin depth of the nanocomposites were also studied, the cut-off energy and cutoff-wavelength are 5.66 eV and 220 nm. However, the compressive strength, flexural strength, and the lowest friction coefficient value at 1 m/s sliding speed of the best composite sample (PZA15) are 85.2 MPa, 56.7 MPa and 0.311. The highest flexural modulus (846 MPa) of the PZA15 were determined using the 3-point bending test. Further, to check the biocompatibility of these resin-based composites the MTT assay was carried out. The synthesized composite (PZA15) was found to be highly biocompatible with enhanced mechanical and tribological performances. © 2023 Elsevier Ltd and Techna Group S.r.l.
Evaluation of mechanical and thermal properties of thermosetting polymer composites
(Elsevier, 2024) Gagan Bansal; Rakesh Kumar Gautam; Joy Prakash Misra; Chandra Kishore; Abhilasha Mishra; Akarsh Verma
Material characterization and optimization has been the first choice of many researchers in the current scenario. Polymer-based composites are the most desired materials among all other materials because of their easy availability, moldability, and customization characteristics. In this chapter, physical, thermal, and mechanical properties of thermoset polymers are discussed in detail. Some examples of thermosetting polymers are bakelite, epoxies, silicones, vulcanized rubber, polyesters, phenolics, polyurethane, nonisocyanate polyurethane, and melamine-formaldehyde polymers. Physical properties of the material include appearance, color, texture, odor, solubility, density, melting point/boiling point, corrosion resistance, resistivity, and magnetism. Mechanical properties of engineering materials include strength, elasticity, plasticity, ductility, malleability, brittleness, stiffness, hardness, creep, fatigue, resilience, toughness, and weldability, and thermal properties of engineering materials include thermal conductivity, specific heat, thermal expansion, thermal resistance, and thermal shock resistance. Comparative analysis is done among different thermoset polymers and the relevant applications are identified. Further, future prospects of thermoset polymer composites are identified for sustainable development. © 2024 Elsevier Inc. All rights reserved.
Fabrication, structural, and enhanced mechanical behavior of MgO substituted PMMA composites for dental applications
(Nature Research, 2024) Savita Kumari; Rajat Kumar Mishra; Shama Parveen; Sarvesh Kumar Avinashi; Ajaz Hussain; Saurabh Kumar; Monisha Banerjee; Jitendra Rao; Rupesh Kumar; Rakesh Kumar Gautam; Chandkiram Gautam
The most common denture material used for dentistry is poly-methyl-methacrylate (PMMA). Usually, the polymeric PMMA material has numerous biological, mechanical and cost-effective shortcomings. Hence, to resolve such types of drawbacks, attempts have been made to investigate fillers of the PMMA like alumina (Al2O3), silica (SiO2), zirconia (ZrO2) etc. For the enhancement of the PMMA properties a suitable additive is required for its orthopedic applications. Herein, the main motive of this study was to synthesize a magnesium oxide (MgO) reinforced polymer-based hybrid nano-composites by using heat cure method with superior optical, biological and mechanical characteristics. For the structural and vibrational studies of the composites, XRD and FT-IR were carried out. Herein, the percentage of crystallinity for all the fabricated composites were also calculated and found to be 14.79–30.31. Various physical and optical parameters such as density, band gap, Urbach energy, cutoff energy, cutoff wavelength, steepness parameter, electron–phonon interaction, refractive index, and optical dielectric constant were also studied and their values are found to be in the range of 1.21–1.394 g/cm3, 5.44–5.48 eV, 0.167–0.027 eV, 5.68 eV, 218 nm, 0.156–0.962, 4.273–0.693, 1.937–1.932, and 3.752–3.731 respectively. To evaluate the mechanical properties like compressive strength, flexural strength, and fracture toughness of the composites a Universal Testing Machine (UTM) was used and their values were 60.3 and 101 MPa, 78 and 40.3 MPa, 5.85 and 9.8 MPa-m1/2 respectively. Tribological tests of the composites were also carried out. In order to check the toxicity, MTT assay was also carried out for the PM0 and PM15 [(x)MgO + (100 − x) (C5O2H8)n] (x = 0 and 15) composites. This study provides a comprehensive insight into the structural, physical, optical, and biological features of the fabricated PMMA-MgO composites, highlighting the potential of the PM15 composite with its enhanced density, mechanical strength, and excellent biocompatibility for denture applications. © 2024, The Author(s).
Formation of multifunctional ZrO2–MgO-hBN nanocomposite for enhanced bone regeneration and E coli bacteria filtration applications
(Elsevier Ltd, 2020) Ajaz Hussain; Chandkiram Gautam; Asif Jafri; Vijay Kumar Mishra; Abhishek Madheshiya; Amarendra Gautam; Manvandra Kumar Singh; Rakesh Kumar Gautam; Manisha Gupta; Md Arshad; Robert Vajtai; Pulickel M. Ajayan
Due to adequate properties, bone implant materials have attracted much attention to repair the large-sized bone fractures which cannot be auto-healed. Recently, three-dimensional (3-D) nanocomposites were synthesized using two-dimensional (2-D) materials which reveals unexpected performances. In the present study, 3-D mesoporous biocomposites were developed for bone/dental implant applications. A ternary novel biocomposite system ZrO2–MgO-hBN was fabricated with low density, high strength, and mesoporous interconnected architecture using conventional bottom-up synthesis method. Due to remarkable stability in different fluids such as water, minimum essential medium eagle-alpha modification (α-MEM), acids and oils, the fabricated biocomposites displayed multifunctional activities along with suitable proliferation of osteoblast like MG63 cell and filtration of Escherichia coli (E-coli) bacteria from the water. Moreover, the biocomposite exhibited protective nature from harmful ultraviolet (UV) radiation. A new phase of hexagonal boron nitride (h-BN) in the form of highly porous nanotubes was observed that opens the new possibility to optimize the synthesis of porous h-BN nanotubes to explore their further applications. Therefore, based on mechanical, tribological and biological performances, the nanocomposite is a biomimetic material having potential as bone/dental implant and can be used for multifunctional applications. © 2020 Elsevier Ltd and Techna Group S.r.l.
Hemp fiber surface modification: Its effect on mechanical and tribological properties of hemp fiber reinforced epoxy composites
(John Wiley and Sons Inc, 2021) Sudhakar Behera; Rakesh Kumar Gautam; Sunil Mohan; Arghya Chattopadhyay
In this research work, the effects of sodium carbonate and hydrogen peroxide treatment of hemp fiber on the water absorption, mechanical, and tribological properties of hemp fiber reinforced epoxy composites (HFREC) were investigated. The change in surface roughness and fiber size after chemical treatment was confirmed by the scanning electron microscopy (SEM) images. Fourier transform infrared analysis confirmed the removal of hemicellulose and lignin content of the fiber after both the chemical treatment. X-ray diffraction analysis showed an increase in the crystallinity index of the chemically treated fiber. The experimental results also revealed that both sodium carbonate and peroxide modification have resulted in enhancement of water resistance and mechanical properties such as tensile strength and tensile modulus and reduction in impact properties of treated HFREC. Tribological test results revealed that the treated HFREC have improved wear and frictional properties in comparison with untreated HFREC. The best tribological and mechanical properties were exhibited by peroxide treated HFREC, which was also confirmed through the SEM images of worn and fractured surfaces of the composites. © 2021 Society of Plastics Engineers.
High-Temperature Tribology of AA5052/ZrB2 PAMCs
(American Society of Mechanical Engineers (ASME), 2017) Narendra Kumar; Gaurav Gautam; Rakesh Kumar Gautam; Anita Mohan; Sunil Mohan
AA5052/ZrB2 particulate aluminum matrix composites (PAMCs) have been produced by in situ reaction of K2ZrF6 and KBF4 compounds with molten alloy at about 860 °C. Dry sliding wear and friction of composites have been investigated for a particular sliding velocity and sliding distance at different loads from ambient temperature to 200 °C. It is revealed that for a particular load and temperature, wear rate and normalized wear rate decrease with increase in the volume percentage of ZrB2 particles whereas coefficient of friction (COF) shows a reverse trend. Wear rate and COF also increase with increase in temperature for a constant load and composition. Whereas with load for a particular temperature, wear rate and wear rate per unit vol. % ZrB2 increase while COF decreases. Worn surface and wear debris morphology examined under scanning electron microscopy (SEM) and profilometer to understand the wear mechanism revealed that wear mode transition takes place from mild-oxidative to severe-metallic at 100°C for unreinforced alloy, whereas a shifting is observed in transition temperature from 100 to 150°C for composite with 9 vol. % ZrB2 particles. Energy dispersive spectroscopy (EDS) analysis of worn surface confirms the oxidative wear mode. Profilometry results indicate that wear surface has higher surface roughness at higher values of load and temperatures. Prior to wear and friction studies, composites were also characterized by X-ray diffraction (XRD) and SEM for morphology and microstructural characteristics to correlate with wear results. The findings are very helpful to make the AA5052/ZrB2 composites suitable for the applications, where high-temperature wear is a limiting factor. Copyright © 2017 by ASME.
In-situ development of ZrB2 particles and their effect on microstructure and mechanical properties of AA5052 metal-matrix composites
(Elsevier Ltd, 2015) Narendra Kumar; Rakesh Kumar Gautam; Sunil Mohan
AA5052/ZrB2 composites with different volume percent (i.e. 0, 3, 6, 9 and 10vol.%) ZrB2 particles were developed by in-situ reaction of molten AA5052 alloy with two inorganic salts K2ZrF6 and KBF4 at a temperature of 860°C. The in-situ composites were characterized by DTA, XRD, SEM, TEM for reaction analysis and morphology. Their mechanical properties like hardness and tensile properties were evaluated using standard methods. Morphology studies show that grain size of Al-rich phase reduces due to the presence of ZrB2 particles. Microstructural studies also reveal the uniform distribution of second phase particles, clear interface, good bonding, dislocations and morphology of ZrB2 particles. It is found that ZrB2 particles are mostly in nano size with hexagonal or rectangular shape, however, few particles in micron size are also observed. Density and hardness of the composites increases with increase in the amount of reinforcement. Ultimate tensile strength and 0.2% yield strength (YS) also improved continuously with increase in the volume fraction of ZrB2 particles up to 9vol.% but beyond this composition strength reduced. It is important to note that with dispersion of ZrB2 particles in base alloy an improvement in ductility is observed which is contrary to many other composites. © 2015 Elsevier Ltd.
Mechanical and tribological properties of chemically modified jute/epoxy composites
(Taylor and Francis Ltd., 2023) Sudhakar Behera; Rakesh Kumar Gautam; Sunil Mohan; Arghya Chattopadhyay
The purpose of the present work is to assess the effectiveness of low-cost and environmental friendly chemical modification of jute fibres based on the usage of sodium hydroxide (AT), sodium carbonate (ST) and sodium hydrogen carbonate (SHT) on the morphological, water absorption, mechanical and tribological characteristics of jute fibre-reinforced epoxy composites (JFREC). Mechanical properties like tensile strength, tensile modulus and impact strength showed appreciable improvement for the AT JFREC (38.08%, 30.56% and 31.66%), ST JFREC (70.03%, 33.06% and 41.30%) and SHT JFREC (24.69%, 8.88% and 22.61%) when compared to untreated JFREC. The experimental results also confirmed that the improved fibre-matrix adhesion, attained by chemical modification, increased the water absorption resistance and the tribological properties of chemically modified JFREC. Improved mechanical and tribological properties attained by the chemically modified JFREC can be found as a potential application in automotive and packaging industries. © 2023 Institute of Materials, Minerals and Mining Published by Taylor & Francis on behalf of the Institute.
Physiomechanical, Flowability, and Antibacterial Characterization of Silver-Doped Eggshell-Derived Hydroxyapatite for Biomedical Applications
(Springer, 2024) Gagan Bansal; Rakesh Kumar Gautam; Joy Prakash Misra; Abhilasha Mishra
Hydroxyapatite (Ca10(PO4)6(OH)2, HAp), a biocompatible ceramic material, has been the priority source in several biomedical applications due to its bone type composition, crystallography and morphology. In the current research, firstly, HAp powder was synthesized from the waste eggshells using a modified synthesis route, i.e., multistage calcination preceded by a chemical precipitation method for process optimization. Secondly, the silver-doped HAp was synthesized with varying weight percent (0.0, 0.1, 0.2 and 0.5 wt.%) of silver nitrate (AgNO3) in HAp. An increase of 5.52% and 23.68% in maximum compressive strength and Vickers microhardness was observed between the undoped and 0.2 wt.% silver-doped HAp, showing the improved adhesion and bonding strength of the sintered samples. The porosity percentage also decreased with an increase in silver doping and was minimum for HAP0.2Ag (7.969%). The flowability characteristics demonstrate good flow for HAP0.0Ag (HR = 1.175 and CI = 14.89) and HAP0.1Ag (HR = 1.174 and CI = 14.87), and persists the travelable flow up to 0.5 wt.% (angle of repose = 42 ± 1.28, n = 3). Silver doping exhibits a synergistic effect, yielding satisfactory physiomechanical and antibacterial properties up to 0.2 wt.%. Inductively Coupled Plasma Mass Spectroscopy, x-ray Diffraction Technique, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, and Energy-Dispersive Spectroscopy verify the morphology, chemical composition, bonding strength, crystallite size, particle size, lattice strain and phase purity, respectively. Six different bacteria strains, i.e., S. epidermidis, S. aureus, B. subtilis, E. coli DH5α, P. aeruginosa and E. coli, employed for antibacterial characterization confirm the antibacterial nature of silver-doped HAp. Results obtained accentuate the antibacterial nature of silver-doped HAp and its utility in biomedical applications. Graphical Abstract: (Figure presented.). © ASM International 2023.
Synergetic impact of MgO on PMMA-ZrO2 hybrid composites: Evaluation of structural, morphological and improved mechanical behavior for dental applications
(Elsevier Inc., 2024) Savita Kumari; Anuj Verma; Rajat Kumar Mishra; Sarvesh Kumar Avinashi; Shweta; Shweta Singh; Priyatama Behera; Jitendra Rao; Rakesh Kumar Gautam; Bijay Laxmi Pradhan; Krishna Kishor Dey; Manasi Ghosh; Monalisa Mishra; Chandkiram Gautam
This work aims to demonstrate the effect of ZrO2 and MgO inclusion into the Poly(methyl methacrylate) (PMMA). To fabricate novel hybrid composites via heat cure method, various composites (PZM2, PZM4 and PZM6) were synthesized in the system [(95-x) PMMA + 5 ZrO2 + x MgO] (x = 2, 4, and 6) respectively. Density of the prepared composites were determined and varying between 1.035–1.152 g/cm3. X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) followed by EDAX and mechanical testing were performed to evaluate the fabricated composite properties. Moreover, to explore the structure of the fabricated composites the 13 C CP-MAS SSNMR and 1 H-13 C Phase-Modulated Lee Goldberg (PMLG) HETCOR Spectrum were recorded which clarify chemical shifting and motional dynamics of the composites. Mechanical tests were performed by UTM and the obtained parameters such as compressive strength, Young's modulus, fracture toughness, brittleness coefficient, flexural strength and flexural modulus are found to be in the range of 91–100 MPa, 0.48–0.51 GPa, 9.122–9.705 MPa.m1/2, 0.66–0.815, 51.03–42.78 MPa and 499–663 MPa respectively. Some more mechanical parameters such as proportional limit, elastic limit, failure strength, modulus of resilience and modulus of toughness were also calculated. Furthermore, tribological properties were also determined and the coefficient of friction (COF) was decreased by 17.4 % and 38 % for composite PZM6 at 20 N and 40 N as compared to the composite PZM2 and the lowest wear volume of 1.55 mm3 was observed for PZM2, whereas the maximum volume loss of 5.64 mm3 is observed for composite PZM6. To check out the biocompatibility, cytotoxicity and genotoxicity of the fabricated composites the Trypan-blue assay was also performed for PZM2 and PZM6 composites. Dissection on the gut of larvae was also performed on the both composites followed by DAPI and DCFH-DA staining. Therefore, these synthesized samples can be used for the fabrication of denture materials. © 2024 Elsevier Inc.
Synthesis and characterization of poly (methyl methacrylate)/ silver-doped hydroxyapatite dip coating on Ti6Al4V
(Elsevier B.V., 2024) Gagan Bansal; Rakesh Kumar Gautam; Joy Prakash Misra; Abhilasha Mishra
This study intends to analyze the properties and potential applications of a novel composite coating composed of poly (methyl methacrylate) (PMMA) and silver-doped hydroxyapatite (HAPAg) produced from waste eggshells, which was dip-coated onto Ti6Al4V substrates. Medical implants frequently made of the titanium alloy Ti6Al4V can benefit greatly from surface coatings in terms of biocompatibility and performance. In order to add antibacterial and osteoconductive characteristics, silver-doped hydroxyapatite nanoparticles were dispersed within a PMMA matrix to create the PMMA/HAPAg composite coating. The coated samples report an average contact angle (CA) between 70 and 750 and total surface free energy (SFE) between 35 and 50 mJ/m2, which signifies its improved wettability. The 7.03% change in hydrophilicity was observed between PMMA/H0 (75.270 ± 1.690) and PMMA/H20 (700 ± 1.440) coated samples. The increase in adhesion strength and coating thickness with the increase in HAPAg reinforcement was observed. The surface morphology of the defective zones was examined using scanning electron microscopy (SEM), and information on the elemental composition of synthesized was obtained using Inductively Coupled Plasma Mass Spectroscopy (ICPMS), Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffractogram (XRD). Atomic force microscopy (AFM) reveals the surface roughness; root mean square roughness, roughness profile, skewness and kurtosis of the coated samples. The contact angle reports the hydrophilicity and SFE. Finally, the results conclude that the composite coating had a consistent distribution of HAPAg nanoparticles incorporated within the PMMA matrix. The minimal presence of Ag ions on the surface indicates the coating's potential antibacterial properties, and it is highly recommended for dental applications. © 2024 Elsevier B.V.
Traditional Knowledge in Drug Development and the Rights of Indigenous Peoples: A Legal and Ethical Perspective
(Ashdin Publishing, 2024) Roshan Lal; Babita Baeraiya; Rashmi Thakur; Rakesh Kumar Gautam; Saurav Narayan; Deepesh Yadav; Puneet Pathak; Sukanya Singha
This paper delves into the intersection of traditional knowledge and drug development, highlighting the critical contributions of indigenous wisdom to pharmaceutical advancements while examining the associated legal and ethical challenges. Traditional knowledge, encompassing centuries of indigenous expertise in medicinal plants and natural remedies, has been instrumental in the discovery of significant drugs, such as aspirin derived from willow bark. Despite the growing global interest in natural products and traditional medicine, indigenous communities face significant challenges in protecting their knowledge and securing their rights against exploitation and biopiracy. The paper critically evaluates the inadequacies of existing Intellectual Property Rights (IPR) frameworks in safeguarding traditional knowledge, addressing the complexities inherent in applying patent laws to such knowledge. It explores relevant international treaties, such as the Convention on Biological Diversity (CBD) and the Nagoya Protocol on Access and Benefit-sharing (ABS), which aim to regulate access and ensure fair compensation for indigenous communities. Furthermore, it examines national legal frameworks in countries like India, Brazil, and Peru, assessing their effectiveness in promoting fair benefit-sharing and protecting indigenous rights. In addition, the paper addresses ethical and legal challenges related to biopiracy and the necessity of obtaining Free, Prior, and Informed Consent (FPIC) from indigenous communities. Through detailed case studies, it highlights both successful and unsuccessful efforts to integrate traditional knowledge into drug development, offering valuable lessons and best practices. The paper concludes with policy recommendations aimed at reforming IPR laws, enhancing international and national mechanisms, and promoting equitable benefit-sharing to ensure that traditional knowledge is utilized responsibly, fairly, and sustainably. © 2024 Roshan Lal, et al.