IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Fabrication and multifunctional properties of fluorine-free durable nickel stearate based superhydrophobic cotton fabric
No full textA fluorine-free superhydrophobic cotton fabric based on nickel stearate with multifunctional properties has been fabricated by a two step simple solution process. The cotton fabric (aNS-CF) exhibits static water contact angle, similar to 160 degrees, and water shedding angle, < 10 degrees, due to in-situ formation of hierarchical (micro and nano) broccoli-like structures of nickel stearate. The superhydrophobic cotton fabric, having superoleophilic property, has been used for separation of a series of light/heavy oil-water mixtures, and similar to 99% separation efficiency has been achieved after 10 cycles of separation process and it has been found to be slightly reduced to similar to 98% after 50 cycles. Antifouling and self-cleaning performance of the fabric has been evaluated effectively using solid and liquid contaminants as well as some common food liquids. The coating exhibits significant mechanical and chemical robustness and laundering durability in harsh conditions. The coated fabric possesses antibacterial (gram-negative E. coli and gram-positive S. aureus) and antifungal (C. albicans) properties leading to similar to 99.99% reduction in microbial growth, which has been remarkably sustained after 50 cycles of washing, abrasion and separation of oil-water mixtures. The stable multifunctional properties of the fabric exhibits a great potential towards a huge domain of practical implementations in smart textiles. GRAPHICS]
Fabrication, characterization and optimization of industrial alpha alumina powders based ceramic membrane supports and its applicative potential for CO2/N-2 separation
No full textIn this investigation, an economically feasible strategy has been proposed for the fabrication of good quality membrane support by utilizing low-cost industrial-grade alumina powders, coded as A-16SG and CT-1200SG with an average particle size of 0.44 and 1.41 mu m, respectively. Herein, the meticulous alteration of the processing parameters and the targeted utilization of industrial grade powders with distinctive particle morphologies have shown promising aspect towards governing the overall sintering and densification behavior, pore morphology and the microstructural facets of the sintered alumina compacts. More precisely, while connecting the structure-property relationship aspect, the broader particle size distribution and the higher quartile ratio of CT-1200SG powders lends to originate relatively higher average pore size and wider pore size distribution in the as-optimized sintered membrane support system in comparison to the narrow particle sized and low quartile ratio comprising A-16SG powder. Additionally, the near surface morphology of the intermediate layers deposited over the two distinctive membrane support systems via implementing differential colloidal chemistry of the respective sols have also been demonstrated for the precise understanding of the role of particle morphology on the progressive perseverance of pore characteristics of the overall asymmetric graded membrane substrate. Finally, the performance evaluation of the alumino-silicate membrane layer assembled on the tailor-made multilayered graded cost-competent alumina support system has been executed which revealed comparable CO2/N2 gas permeance of 46.44GPU and 534.25GPU along with the selectivity of 12.5 and 1.9 for the respective A-16SG and CT-1200SG powders based individual support systems under nearly identical flue gas separation conditions
Decisive Role of Polymer-Bovine Serum Albumin Interactions in Biofilm Substrates on ``Philicity'' and Extracellular Polymeric Substances Composition
No full textFormation of extracellular polymeric substances (EPS) is a crucial step for bacterial biofilm growth. The dependence of EPS composition on growth substrate and conditioning of the latter is thus of primary importance. We present results of studies on the growth of biofilms of two different strains each, of the Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae, on four polymers used commonly in indwelling medical devices-polyethene, polypropylene, polycarbonate, and polytetrafluoroethylene-immersed in bovine serum albumin (BSA) for 24 h. The polymer substrates are studied before and after immersing in BSA for 9 and 24 h, using contact angle measurement (CAM) and field emission scanning electron microscopy (FE-SEM) to extract, respectively, the ``philicity'' phi (defined as -cos theta, where theta is the contact angle of the liquid on the solid at a particular temperature and ambient pressure) and spatial Hirsch parameter H (defined from the relation F(r) similar to r(2H), where F(r) is the mean squared density fluctuation at the sample surface). H = 0.5, 0.5 signifies no correlation, anticorrelation, and correlation, respectively. The substrates are seen to transform from large hydrophobicity to near amphiphilicity with the formation of a BSA conditioning surface layer, and the H-values distinguish the length scales of 100, 500, and 2000 nm, with the anticorrelation increasing with length scale. Biofilms of E. coli did not grow on bare PTFE and HDPE substrates. Biofilms grown on BSA-covered surfaces are studied with CAM, FE-SEM, Fourier transform infrared (FTIR), and surface-enhanced Raman spectroscopy (SERS). Both spectra and f-values were independent of bacterial species but dependent on the polymer, while H-values show some bacterial variation. Thus, EPS composition and wetting properties of the corresponding bacterial biofilms seem to be decided by the interaction of the conditioning BSA layer with the specific polymer substrate
Effects of Hot Isostatic Pressing on the Properties of Laser-Powder Bed Fusion Fabricated Water Atomized 25Cr7Ni Stainless Steel
Get PDF25Cr7Ni stainless steel (super duplex stainless steels) exhibits a duplex microstructure of ferrite and austenite, resulting in an excellent combination of high strength and corrosion resistance. However, Laser-Powder Bed Fusion fabrication of a water-atomized 25Cr7Ni stainless steel of novel chemical composition resulted in a purely ferritic microstructure and over 5% porosity. The current study investigated the effects of two hot isostatic pressing parameters on the physical, mechanical, and corrosion properties as well as microstructures of water-atomized 25Cr7Ni stainless steel of novel composition fabricated by L-PBF for the first time in the literature. The corrosion behaviour was studied using linear sweep voltammetry in a 3.5% NaCl solution. The Hot Isostatic Pressing-treated sample achieved over 98% densification with a corresponding reduction in porosity to less than 0.1% and about 3 similar to 4% in annihilation of dislocation density. A duplex microstructure of ferrite 60% and austenite 40%was observed in the X-Ray Diffraction and etched metallography of the HIP-treated samples from a purely ferritic microstructure prior to the HIP treatment. With the evolution of austenite phase, the HIP-treated samples recorded a decrease in Ultimate Tensile Strength, yield strength, and hardness in comparison with as-printed samples. The variation in the morphology of the evolved austenite grains in the HIP-treated samples was observed to have a significant effect on the elongation. With a reduction in porosity and the evolution of the austenite phase, the HIP-treated samples showed a higher corrosion resistance in comparison with the as-printed samples
Ferromagnetic Ni1-xVxO1-y Nano-Clusters for NO Detection at Room Temperature: A Case of Magnetic Field-Induced Chemiresistive
No full textSurface modulation of functional nanostructures is an efficient way of improving gas sensing properties in chemiresistive materials. However, synthesis methods employed so far in achieving desired performances are cumbersome and energy intensive. Moreover, nano-engineering-induced magnetic properties of these materials which are expected to enhance sensing responses have not been utilized until now in improving their interaction with target gases. In particular for gasses with paramagnetic nature such as NO or NO2, the inherent magnetic property of the chemiresistor might assist in enabling superior sensing performance. In this work, vanadium-doped NiO nano-clusters with ferromagnetic behavior at room temperature have been synthesized by a simple and effective combination of soft chemical routes and employed in efficient and selective detection of paramagnetic NO gas. While NiO is typically anti-ferromagnetic, the nanoscale engineering of NiO-and V-doped NiO samples have been found to tune the inherent anti-ferromagnetic behavior into room-temperature ferromagnetism. Surface modification in terms of formation of nano-clusters led to an increased Brunauer- Emmett-Teller surface area of similar to 120 m2/g. The sample Ni0.636V0.364O has been observed to exhibit a selective and high response of similar to 98% to 1 ppm NO at room temperature with fast response (14 s) and recovery (95 s). The improved sensing response of this sample compared to other doped NiO variants could be explained in terms of lower remnant magnetic moment of the sample accompanied with higher excess negative charge at the surface. The sensing response of this sample was increased by 30% in the presence of an external magnetic field of 280 gauss, highlighting the importance of magnetic ordering in chemiresistive gas sensing between the magnetic sensor material and target analyte. This material stands as a potential gas sensor with excellent NO detection properties
Nonmonotonic Magnetic Field Dependence of Remnant Ferroelectric Polarization in Reduced Graphene Oxide-BiFeO3 Nanocomposite
No full textThe thin-film heterostructures or nanocomposites exhibit vastly different properties from those observed in bulk systems. Herein, in a nanocomposite of reduced graphene oxide (RGO) and BiFeO3 (BFO), the remnant ferroelectric polarization is found to follow nonmonotonic magnetic field dependence at room temperature as the applied magnetic field is swept across 0-20 kOe on a pristine sample. Bulk BiFeO3, in contrast, exhibits monotonic suppression of polarization under magnetic field. The remanent ferroelectric polarization, in the present case, is determined, primarily, from powder neutron diffraction patterns recorded under 0-20 kOe field. The nanosized (approximate to 20 nm) particles of BFO are anchored onto the graphene sheets of RGO via Fe-C bonds with concomitant rise in covalency in the Fe-O bonds. Field-dependent competition between positive and negative magnetoelectric coupling arising from magnetostriction due to, respectively, interface and bulk magnetization appears to have given rise to the observed nonmonotonic field dependence of polarization. The emergence of Fe-C bonds and consequent change in the magnetic and electronic structure of the interface region have influenced coupling between ferroelectric and magnetic properties remarkably and thus creates a new way of tuning the magnetoelectric properties via reconstruction of interfaces in nanocomposites or heterostructures of graphene/single-phase-multiferroic systems
Particle size mediated investigation of various physicochemical properties of kaolinite clay for fabricating the separator layer of green capacitors
No full textThis article reports size fractionation of a natural clay namely kaolinite for fabricating cost-effective green separator material for energy storage devices. kaolinite is reportedly biocompatible and abundantly available in nature, which makes it cost-effective. Such a low-cost clay is found to be in the nano regime when treated in a ball-milling machine for a prolonged duration (12 h). The enhancement in porosity and surface area have also been observed in the treated nano-clay, which subsequently renders it's dielectric constant (similar to 5000 at 40 Hz frequency) remarkably. Henceforth, it can be argued that crystallinity and aspect ratio (S/V) has a prominent impact on the electrical properties of this natural clay. Cyclic voltammetry and galvanostatic charging-discharging measurements depict high specific capacitance (similar to 185 F g(-1)) in the nano-clay sample without the presence of any redox peak making it a good separator material. The slow electrical discharge rate also approves the storage property of this clay sample quite effectively. Abundance, augmented permittivity with a relatively low tangent loss, high specific capacitance and significant resistivity through the material make this nano-clay material a promising `green' dielectric separator for energy storage applications
Graphene-Coated Halloysite Nanoclay Membrane for the Enhanced Separation of Hydrogen from a Hydrogen-Helium Mixture
No full textThis study highlights the separation of hydrogen from H-2-He mixture gas by a graphene-coated halloysite nanoclay membrane. The graphene-coated clay membrane along with its pure day counterpart is successfully developed and studied for gas separation using hydrogen (H-2)-helium (He) single and mixture gases. Hydrothermal and nonhydrothermal methods were applied for the synthesis of a ``coated'' membrane on a porous alumina substrate from the graphene and halloysite clay. To date, nanoporous zeolites are the potential materials for gas separation based on a molecular sieving mechanism. A similar separation mechanism for hydrogen and helium from mixture gases may not work efficaciously due to the closeness of their kinetic diameter (H-2: 2.89 angstrom and He: 2.6 angstrom). The presence of defects and torn nanopores between graphene layers along with the different surface charges of the inner and outer layer of halloysite nanotubes facilitates the ``coated'' membrane to show an appreciable H-2/He separation factor of similar to 4 using H-2-He (1:1) mixture gas compared to 2.86 for the pure halloysite membrane. The available charge layer of graphene also has a significant contribution for this increased H-2/He selectivity value. The permeate flux of H-2 and He through both the graphene-coated clay membrane and pure clay membrane has also been noted. The permeate flux of pure H-2 and He was 2 x 10(-7) and 1.3 x 10(-7) mol m(-2) s(-1) Pa-1 for the clay membrane, whereas for the ``coated'' clay membrane, the values changed to 0.1 x 10(-7) and similar to 0.05 x 10(-7) mol m(-2) s(-1) Pa-1 at 100 kPa, respectively
Regenerative properties of topically applied 3D electrospun nanoscaled bioactive glass fibers on diabetic oral mucosal defects
No full textDiabetes triggers chronic inflammation, declines the antibacterial action and angiogenesis leading to protracted wound healing. Bioactive glass manifested high regenerative efficacy when used in bone regeneration (1). This study aimed to assess the regenerative efficacy of novel bioactive glass nanofibers (BGnf) on surgically created alveolar mucosal wounds of the diabetic rabbit model. Glass nanofibers(500‐900nm):(1–2mol% of B2O3, 68–69 mol% of SiO2, and 29–30 mol% of CaO) were synthesized via the sol‐gel technique followed by electrospinning of the glass/polymer sol and heat‐treatment of fibers at 700C(2). Fibers analysis broadcasted its amorphous, cross‐linked structure and bioactivity. Following that, 12 healthy New Zealand rabbits were successfully subjected to chemical induction of type I diabetes. Two weeks after diabetes confirmation, two groups of bilateral elliptical maxillary mucosal defects (10 * 3.5 mm) were created. The defects of the experimental group were grafted with BGnf(n = 12), while the other group was the control(n = 12). To evaluate fibers regenerative efficacy, three different assessments (clinical, histological, and immune‐histochemical) were performed at 1, 2 and 3 weeks' time interval(2). After 1 week, BGnf treated wounds showed complete wound regeneration with significantly high‐level VEGF (14.08 ± 3.88%) and collagen I% (6.12 ± 0.49%) expression. Contrariwise, the control group showed suppurative exudates with inflammatory cell infiltration at lamina propria and lower VEGF(3.92 ± 0.222%) and collagen I(3.88 ± 1.934%) expression. After 3 weeks, VEGF and collagen I of BGnf group also recorded a higher expression than the control group. In conclusion, BGnf stimulates in‐ situ soft tissue regeneration, neovascularization and antibacterial action in the wet oral environment in diabetic patients
Wide thermal expansion in Ag-0/Au-0 nanoparticle doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass-ceramics
No full textThis report demonstrates high temperature sealing tendency of alumino-silicate glasses (ASG) on the system SiO2-MgO-Al2O3-B2O3-K2O-MgF2 doped with silver (Ag) and gold (Au) nanoparticles. Density of the melt-quenched (1550 degrees C) glasses were in 2.51-2.55 g.cm(-3). The glasses were heat-treated at 900 +/- 10 degrees C over which the opaque glass-ceramics were obtained with major crystalline phase (XRD) fluorophlogopite mica KMg3(AlSi3O10)F-2] with secondary phase norbergite (Mg2SiO4 center dot MgF2). FESEM study indicated the development of Rod-like and rock-like crystallite particles (size similar to 1-4 mm) randomly dispersed in mother glass-ceramic which was restructured into nanocrystalline morphology (crystallite size similar to 100- 400 nm) with the aid of Ag-or Au-nanoparticles. The significant change in microstructure influenced the corresponding density (2.51-2.55 g.cm(-3)) and thermal expansion characteristics. Coefficient of thermal expansion (CTE) for ASG was estimated to be 9.96 +/- 0.10 x 10(-6)/K (50-800 degrees C), which increased to 10.46-11.01 x 10(-6)/K when doped with Ag-or Au-content. Such wide CTE (11.01 +/- 0.11 x 10(-6)/K) value matches well with the CTE of ceramic/metallic materials used for high temperature application thus Ag-doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass can be a suitable for high temperature sealing application (like SOFC). (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Virtual Conference on Advanced Nanomaterials and Applications