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"Gopakumar, A"
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A Review on Plant Cellulose Nanofibre-Based Aerogels for Biomedical Applications
by
Olaiya, N.G.
,
Yahya, Esam Bashir
,
Hossain, Md. Sohrab
in
Aerogels
,
Antibiotics
,
Biocompatibility
2020
Cellulose nanomaterials from plant fibre provide various potential applications (i.e., biomedical, automotive, packaging, etc.). The biomedical application of nanocellulose isolated from plant fibre, which is a carbohydrate-based source, is very viable in the 21st century. The essential characteristics of plant fibre-based nanocellulose, which include its molecular, tensile and mechanical properties, as well as its biodegradability potential, have been widely explored for functional materials in the preparation of aerogel. Plant cellulose nano fibre (CNF)-based aerogels are novel functional materials that have attracted remarkable interest. In recent years, CNF aerogel has been extensively used in the biomedical field due to its biocompatibility, renewability and biodegradability. The effective surface area of CNFs influences broad applications in biological and medical studies such as sustainable antibiotic delivery for wound healing, the preparation of scaffolds for tissue cultures, the development of drug delivery systems, biosensing and an antimicrobial film for wound healing. Many researchers have a growing interest in using CNF-based aerogels in the mentioned applications. The application of cellulose-based materials is widely reported in the literature. However, only a few studies discuss the potential of cellulose nanofibre aerogel in detail. The potential applications of CNF aerogel include composites, organic–inorganic hybrids, gels, foams, aerogels/xerogels, coatings and nano-paper, bioactive and wound dressing materials and bioconversion. The potential applications of CNF have rarely been a subject of extensive review. Thus, extensive studies to develop materials with cheaper and better properties, high prospects and effectiveness for many applications are the focus of the present work. The present review focuses on the evolution of aerogels via characterisation studies on the isolation of CNF-based aerogels. The study concludes with a description of the potential and challenges of developing sustainable materials for biomedical applications.
Journal Article
Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent
2021
Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.
Journal Article
Precision pulsar timing with the ORT and the GMRT and its applications in pulsar astrophysics
by
Basu, Avishek
,
Neelam Dhanda Batra
,
Choudhary, Arpita
in
Astronomy
,
Astrophysics
,
Equations of state
2018
Radio pulsars show remarkable clock-like stability, which make them useful astronomy tools in experiments to test equation of state of neutron stars and detecting gravitational waves using pulsar timing techniques. A brief review of relevant astrophysical experiments is provided in this paper highlighting the current state-of-the-art of these experiments. A program to monitor frequently glitching pulsars with Indian radio telescopes using high cadence observations is presented, with illustrations of glitches detected in this program, including the largest ever glitch in PSR B0531+21. An Indian initiative to discover sub-\\[\\mu \\]Hz gravitational waves, called Indian Pulsar Timing Array (InPTA), is also described briefly, where time-of-arrival uncertainties and post-fit residuals of the order of \\[\\mu \\]s are already achievable, comparable to other international pulsar timing array experiments. While timing the glitches and their recoveries are likely to provide constraints on the structure of neutron stars, InPTA will provide upper limits on sub-\\[\\mu \\]Hz gravitational waves apart from auxiliary pulsar science. Future directions for these experiments are outlined.
Journal Article
Robust Superhydrophobic Cellulose Nanofiber Aerogel for Multifunctional Environmental Applications
by
Rizal, Samsul
,
Seantier, Bastien
,
Gopakumar, Deepu A.
in
Adsorption
,
Aerogels
,
Aqueous solutions
2019
The fabrication of superadsorbent for dye adsorption is a hot research area at present. However, the development of low-cost and highly efficient superadsorbents against toxic textile dyes is still a big challenge. Here, we fabricated hydrophobic cellulose nanofiber aerogels from cellulose nanofibers through an eco-friendly silanization reaction in liquid phase, which is an extremely efficient, rapid, cheap, and environmentally friendly procedure. Moreover, the demonstrated eco-friendly silanization technique is easy to commercialize at the industrial level. Most of the works that have reported on the hydrophobic cellulose nanofiber aerogels explored their use for the elimination of oil from water. The key novelty of the present work is that the demonstrated hydrophobic cellulose nanofibers aerogels could serve as superadsorbents against toxic textile dyes such as crystal violet dye from water and insulating materials for building applications. Here, we make use of the possible hydrophobic interactions between silane-modified cellulose nanofiber aerogel and crystal violet dye for the removal of the crystal violet dye from water. With a 10 mg/L of crystal violet (CV) aqueous solution, the silane-modified cellulose nanofiber aerogel showed a high adsorption capacity value of 150 mg/g of the aerogel. The reason for this adsorption value was due to the short-range hydrophobic interaction between the silane-modified cellulose nanofiber aerogel and the hydrophobic domains in crystal violet dye molecules. Additionally, the fabricated silane-modified cellulose nanofiber hydrophobic aerogels exhibited a lower thermal conductivity value of 0.037 W·m−1 K−1, which was comparable to and lower than the commercial insulators such as mineral wools (0.040 W·m−1 K−1) and polystyrene foams (0.035 W·m−1 K−1). We firmly believe that the demonstrated silane-modified cellulose nanofiber aerogel could yield an eco-friendly adsorbent that is agreeable to adsorbing toxic crystal violet dyes from water as well as active building thermal insulators.
Journal Article
Comparison of rocuronium at two different doses and succinylcholine for endotracheal intubation in adult patients for elective surgeries
by
Chavan, S
,
Gopakumar, A
,
Gangadharan, S
in
Comparative analysis
,
Intubating conditions; intubating time; neuromuscular block; rocuronium; succinylcholine
,
Neuromuscular blocking agents
2016
Background: The effects of rocuronium at two different doses, that is, 0.6 mg/kg (2 × ED95) and 0.9 mg/kg (3 × ED95), were compared with succinylcholine (2 mg/kg) when used for endotracheal intubation in adult patients for elective surgeries under general anesthesia.
Materials and Methods: Ninety patients were divided into three groups of 30 each. Groups A, B received injection rocuronium at 0.6 mg/kg, 0.9 mg/kg respectively and Group C received succinylcholine at 2 mg/kg. Onset of action of relaxant, intubation conditions, time taken to intubate and duration of action were compared.
Statistical Analysis Used: To compare the statistical difference in the age, weight, height of the study subjects, onset of action of relaxant, intubation conditions, time taken to intubate, and duration of action analysis of variance and unpaired t-test were used.
Results: The onset time was considerably shorter with rocuronium 0.9 mg/kg than 0.6 mg/kg. The onset time of rocuronium 0.9 mg/kg was found to be significantly longer than succinylcholine 2 mg/kg. Time taken to intubate was shortest with succinylcholine 2 mg/kg. The time taken to intubate with the rocuronium 0.9 mg/kg was found to be comparable to that of rocuronium 0.6 mg/kg. Intubation score of rocuronium 0.9 mg/kg was the best (17.75), which was comparable with succinylcholine. However, the intubation score obtained with rocuronium 0.6 mg/kg was inferior. Duration of action was shortest with succinylcholine. The duration of action is prolonged when the dose of rocuronium is increased from 0.6 to 0.9 mg/kg.
Conclusion: Rapid sequence induction of anesthesia with propofol and fentanyl, succinylcholine allowed a more rapid endotracheal intubation sequence and created superior intubation conditions than rocuronium. However, the technique of using a large dose of rocuronium to achieve perfect conditions for tracheal intubation may have application whenever succinylcholine is relatively contraindicated.
Journal Article
Gravitational physics in the context of Indian astronomy: A vision document
by
Mukhopadhyay, Banibrata
,
Sarkar, Sudipta
,
Kashyap, Rahul
in
Astronomy
,
Astrophysics
,
Astrophysics and Astroparticles
2024
Contributions from the Indian gravity community have played a significant role in shaping several branches of astronomy and astrophysics. This document reviews some of the most important contributions and presents a vision for gravity research in the context of astronomy and astrophysics in India. This is an expanded version of one of the chapters in the recently released Vision Document of the Astronomical Society of India.
Journal Article
A Computational Study on Acoustic Absorbance of Hydrophilic Cellulose Nanofiber Based Aerogel with Excellent Flame Retardant and Acoustic Insulation Property for Structural Building Applications
by
Basheer, Jishana
,
Gopakumar, Deepu A.
,
Pasquini, Daniel
in
absorbance
,
absorption
,
Acid resistance
2025
The research aims to ensure the structural stability of nanocellulose-based aerogels in humid environments while imparting flame-retardant properties, alongside their inherent thermal and acoustic insulation capabilities. Building on the established flame retardancy of citric acid-based nanocellulose, our study marks a significant advancement by employing a simple and efficient methodological approach. We introduce a simple and facile technique for crosslinking CNF aerogel using a single crosslinking agent for extraction and modification. The cross-linked CNF aerogel shows a 91% porosity with a low density (0.15 g/cm
3
) which is also positively influenced by the morphological studies. In addition, the inclusion of citric acid into CNF improves water stability, mechanical performance (7.8 N/mm
2
for pure CNF and 8.9 N/mm
2
for cross-linked CNF aerogels), and thermal stability, while reducing the residue of the cross-linked material to 1.6% from 6.4% of pure CNF aerogel. The cross-linking of aerogel by citric acid could enhance fire resistance by lowering the production of hazardous and combustible gases. Furthermore, the cross-linked CNF aerogel was evaluated with a thickness of 40 mm, as the pure CNF aerogel demonstrated optimal sound absorption behavior at this thickness according to simulations conducted using COMSOL Multiphysics software. This work contributes to the broader understanding of how nanocellulose can be engineered for structural building applications, paving the way for further innovations in environmentally friendly aerogel technologies.
Graphical Abstract
Journal Article
Functional Melamine-Formaldehyde Cross-linked Cellulose Nanofiber Based Aerogels with Excellent Flame Retardancy for Thermal-Acoustic Insulation Applications
by
Seantier, Bastien
,
George, Jinu Jacob
,
Gopakumar, Deepu A
in
Acoustic insulation
,
Aerogels
,
Biodegradation
2024
Biodegradable aerogels possessing flexibility and high strength are appealing for applications in construction, acoustic and thermal insulation. However, their susceptibility to flammability presents a significant challenge. Enhancing the flame retardancy of these aerogels has been a prominent focus of research, with the widespread use of inorganic fillers and layered materials for this purpose. In the current study, our objective is to fabricate cellulose nanofiber aerogels characterized by low density, exceptional flame retardancy, high mechanical properties, and thermal insulation. This is achieved through the cross-linking of melamine and formaldehyde under aqueous conditions using an eco-friendly freeze-drying process, followed by post-curing. The resulting aerogels demonstrate flexibility, effective sound absorption within the mid-frequency range, and outstanding flame retardancy (Limiting Oxygen Index ∼33%) with a non-flammable behaviour. The thermal conductivity of the fabricated melamine formaldehyde-modified cellulose nanofiber (MF-CNF) aerogels was 0.064 ± 0.014 W/m.K. MF-CNF aerogels exhibited a Time to Ignition (TTI) of 489 s, whereas pristine CNF aerogels only have 3 s. This improvement was attributed to the concurrent reductions in both the Peak Heat Release Rate (PHRR) and Fire Growth Rate (FIGRA) of MF-CNF aerogels. The straightforward melamine formaldehyde modification of CNF aerogels enhances their mechanical strength as well as fire resistance. These sustainable multifunctional aerogels hold great potential for a variety of real-life applications in the realm of buildings and its structures for ensuring fire safety and sound insulation.
Journal Article
'A bridge too far' – the negative impact of a bridge prosthesis on gingival health and its conservative management
2013
Key Points
Highlights the alternative non-surgical and conservative management of inflamed gingivae adjacent to a failing bridge.
Stresses the importance of careful planning of bridge and pontic design, as well as the use of good clinical technique.
Emphasises the need for access for effective plaque removal in maintaining harmony with the adjacent periodontium.
Bridges are commonly used to replace missing teeth. Periodontal health may, however, be compromised by ill-fitting margins and excess cement. This case report describes the conservative management of chronic gingival inflammation adjacent to the resin-bonded retainers of an anterior bridge by gingival remodelling via a removable prosthesis. This avoided the need for surgical intervention and re-established a suitable gingival profile before placement of a definitive cantilever resin-bonded bridge.
Journal Article
Neutron Star Physics in the Square Kilometre Array Era: An Indian Perspective
by
Bhattacharya, Dipankar
,
Gupta, Yashwant
,
Bagchi, Manjari
in
Astronomy
,
Astrophysics and Astroparticles
,
Magnetic fields
2016
It is an exceptionally opportune time for astrophysics when a number of next-generation mega-instruments are poised to observe the Universe across the entire electromagnetic spectrum with unprecedented data quality. The Square Kilometre Array (SKA) is undoubtedly one of the major components of this scenario. In particular, the SKA is expected to discover tens of thousands of new neutron stars giving a major fillip to a wide range of scientific investigations. India has a sizeable community of scientists working on different aspects of neutron star physics with immediate access to both the uGMRT (an SKA pathfinder) and the recently launched X-ray observatory Astrosat. The current interests of the community largely centre around studies of (a) the generation of neutron stars and the SNe connection, (b) the neutron star population and evolutionary pathways, (c) the evolution of neutron stars in binaries and the magnetic fields, (d) the neutron star equation of state, (e) the radio pulsar emission mechanism, and (f) the radio pulsars as probes of gravitational physics. Most of these studies are the main goals of the SKA first phase, which is likely to be operational in the next four years. This article summarizes the science goals of the Indian neutron star community in the SKA era, with significant focus on coordinated efforts among the SKA and other existing/upcoming instruments.
Journal Article