IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Green synthesis, characterization, antimicrobial and cytotoxic effect of silver nanoparticles using arabinoxylan isolated from Kalmegh
No full textA green synthesis of silver nanoparticles was synthesized by AgNO3 with arabinoxylan, isolated from green stem of Andrographis paniculata (Kalmegh). The synthesized Ag NPs-arabinoxylan conjugates were characterized by UV-vis spectroscopy, FE-SEM, TEM, XRD, TGA, EDX, and Zeta potential experiments. The Ag NPs formation was established by the surface plasmon resonance band similar to 410.25 nm. SEM image showed mostly spherical morphology of Ag NPs. The fcc crystalline nature was identified by XRD, SAED and the size were 24.5 and 25 nm from TEM and XRD analysis respectively. The prepared Ag NPs showed dose-dependent antimicrobial activity against Streptococcus pneumonia, Candida albicans and E. coli. The nanoparciles damage 4% hemolysis to human RBCs at 12.5 mu g/mL. MTT assay of Ag NPs showed that half of the cell killed at 10 mu g/mL and wound healing assay observed effective inhibition cell proliferation. (c) 2020 Elsevier B.V. All rights reserved
Zirconia assisted crystallization of ferroelectric BaBi2Nb2O9 based glass-ceramics: Kinetics, optical and dielectrical properties
No full textCrystallization of ferroelectric BaBi2Nb2O9 (BBN) based glass-ceramics (GCs) doped with different amounts of zirconia (ZrO2) as nucleating agent are carried out via the synthesis of base glasses through melt quenching technique followed by temperature controlled crystallization. For the first time, transparent BBN based GCs have been synthesized with ZrO2 promoting bulk nucleation and facilitating evolution of BBN nanocrystals, which was otherwise difficult in the undoped glass. Non-isothermal DSC studies and several trial heat-treatments facilitated in determining the crystallization temperature of 630 degrees C, at which controlled rate of crystallization was feasible and crystallite size could be controlled in nanometric scale. Comparative crystallization kinetics studies along with XRD and TEM analyses elucidated the role of ZrO2 as nucleating agent in crystallization of the BBN GCs. The refractive index (RI) of the GCs has been increased compared to the corresponding base glasses and found in the range of 1.833-1.854. When ceramized for 30 h, the dielectric constant of the undoped GC has been found to be 131.3 which have been increased enormously to 301 for the 5 mol% ZrO2 doped GC. A maximum polarization of 2.4 mu C/cm(2) and recoverable energy storage density of 0.014 J/cm(3) has been obtained at 150 degrees C for the 5 mol% ZrO2 doped 30 h heat-treated GC. (c) 2020 Elsevier B.V. All rights reserved
Influence of NaF on the ionic conductivity of sodium aluminophosphate glass electrolytes
No full textThis work elucidated the influence of NaF on the structure and ion conductivity of Na2O-Al2O3-P2O5-Nb2O5 (F-0) glass. The enhancement in ionic conductivity of F-0 glass due to the individual NaF substitution for equal mol% of Na2O, Al2O3 and P2O5 have been thoroughly studied. Irrespective of the substitution for any oxides, the addition of NaF increased the concentration of Al(O,F)6 and isolated the PO43- tetrahedral units. Impedance analysis has shown that the substitution of NaF for Al2O3 has lowered the activation energy and improved the ionic conductivity significantly, which demonstrates this glass composition to be a promising material for solid state sodium ion batteries
Bismuth-doped fiber as Q-switcher in hafnium bismuth erbium co-doped fiber laser
No full textWe demonstrate a compact, all-fiber Q-switched hafnium bismuth erbium co-doped fiber laser based on bismuth-doped fiber (BDF) as the saturable absorber (SA). The laser cavity was constructed using a homemade hafnium bismuth erbium co-doped fiber as gain medium. It was found that stable Q-switched pulses operating at 1531.74 nm can be readily generated when the 980 nm pump power is raised above the threshold of 96 mW. By increasing the pump power to the maximum power of 198 mW, the repetition rate was tunable from 27.2 to 59.1 kHz while the pulse width reduces from 36.3 to 6.8 mu s. At the maximum pump power, the Q-switched laser produced a pulse energy of 10.1 nJ. The finding provides evidence of the possibility of BDF as an effective SA for Q-switched laser operating in 1.5 mu m region
Portable and rapid arsenic speciation in synthetic and natural waters by an As(V)-selective chemisorbent, validated against anodic stripping voltammetry
Get PDFInorganic arsenic speciation, i.e. the differentiation between arsenite and arsenate, is an important step for any program aiming to address the global issue of arsenic contaminated groundwater, whether for monitoring purposes or the development of new water treatment regimes. Reliable speciation by easy-to-use, portable and cost-effective analytical techniques is still challenging for both synthetic and natural waters. Here we demonstrate the first application of an As(V)-selective chemisorbent material for simple and portable speciation of arsenic using handheld syringes, enabling high sample throughput with minimal set-up costs. We first show that ImpAs efficiently removes As(V) from a variety of synthetic groundwaters with a single treatment, whilst As(III) is not retained. We then exemplify the potential of ImpAs for simple and fast speciation by determining rate constants for the photooxidation of As(III) in the presence of a TiO2 photocatalyst. Finally, we successfully speciate natural waters spiked with a mix of As(III) and As(V) in both Indian and UK groundwaters with less than 5 mg L-1 dissolved iron. Experimental results using ImpAs agreed with anodic stripping voltammetry (ASV), a benchmark portable technique, with analysis conditions optimised here for the groundwaters of South Asia. This new analytical tool is simple, portable and fast, and should find applications within the overall multi-disciplinary remediation effort that is taking place to tackle this worldwide arsenic problem. (C) 2020 Elsevier Ltd. All rights reserved
Direct measurement of interfacial Dzyaloshinskii-Moriya interaction at the MoS2/Ni80Fe20 interface
No full textWe report on a direct measurement of sizable interfacial Dzyaloshinskii-Moriya interaction (iDMI) at the interface of two-dimensional transition metal dichalcogenide (2D-TMD), MoS 2 and Ni 80 Fe 20 (Py), using Brillouin light scattering spectroscopy. A clear asymmetry in spin-wave dispersion is measured in MoS 2/Py/Ta, while no such asymmetry is detected in the reference Py/Ta system. A linear scaling of the DMI constant with the inverse of Py thickness indicates the interfacial origin of the observed DMI. We further observe an enhancement of DMI constant in a three to four layer MoS 2/Py system (by 56%) as compared to that in two layer MoS 2/Py, which is caused by a higher density of MoO 3 defect species in the case of three to four layer MoS 2. The results open possibilities of spin-orbitronic applications utilizing the 2D-TMD-based heterostructures
ZnO/ZnBi2O4 nanocomposites with p-n heterojunction as durable visible-light-activated photocatalysts for efficient removal of organic pollutants
No full textNovel ZnO/ZnBi2O4 nanocomposites were fabricated by integrating ZnO with ZnBi2O4 nanoparticles via a calcination process and the capability for photodegradation of diverse contaminants in aqueous solution was explored. Comprehensive morphological, structural, textural, optical, and photoelectrochemical characterization of the prepared samples were executed. The experimental results demonstrated that the as-fabricated heterojunctions can remarkably enhance photocatalytic ability for the degradation of RhB in comparison with the ZnO and ZnBi2O4 components. Furthermore, the optimized ZnO/ZnBi2O4 (10%) sample, with suitable photostability, represented great visible-light-induced photocatalytic efficiency towards the degradation of MB, fuchsine, and MO. The significantly boosted photocatalytic performance was associated with the enhanced visible-light spectral response, inhibited recombination of the charge carriers, and improved textural features, which verified by optical, photoelectrical, electrochemical impedance spectroscopy, and textural measurements. Besides, based on the formed p-n heterojunction between the components, the photocatalytic mechanism was discussed and the conceivable electrons/holes migration and separation pathways were also suggested. (C) 2020 Elsevier B.V. All rights reserved
Novel ZnO/CuBi2O4 heterostructures for persulfate-assisted photocatalytic degradation of dye contaminants under visible light
No full textNew visible-light-induced photocatalysts were synthesized through a hydrothermal method, which possess excellent activation efficiency for potassium persulfate (PS) to remove water contaminants. The features of as-synthesized nanocomposites were studied by different instruments. The results showed that the binary ZnO/CuBi2O4 (5.0 %) sample has best photocatalytic capability in the elimination of methyl orange (MO), rhodamine B (RhB), and Congo red (CR). The photodegradation rate constant of RhB over the ZnO/CuBi2O4 (5.0 %) photocatalyst in the existence of 1.48 mM of PS ions, was 178 x 10(-4) min(-1), which is about 26.4, 5.11, 4.31, and 2.44-times as large as the pristine ZnO, PS ions, ZnO/PS, and ZnO/CuBi2O4 (5.0 %) nanocomposite, respectively. The improving photodegradation efficiency was attributed to larger surface area, high absorption of visible light, and the formation of heterojunction at the interface of ZnO and CuBi2O4 nanoparticles. In our view, this study supplies a new method for the production of effective heterojunction photocatalysts using ZnO, which could solve environmental problems according to the practical requirements
One pot method to synthesize three-dimensional porous hydroxyapatite nanocomposite for bone tissue engineering
No full textA three-dimensional porous hydroxyapatite nanocomposite has been synthesized by a simple, less energy consuming and cost effective one-pot method. In this study, gelatin foam has been used as pore forming agent and incorporated in carboxymethyl cellulose-hydroxyapatite system in composite formation stage. A three-dimensional porous polymers-hydroxyapatite nanocomposite has been formed as a final product. The synthesized porous nanocomposite has been thoroughly characterized by different techniques. It was found that the nanocomposite is highly porous with almost 80% porosity, and has multi-scale pores from 2.5 to 900 mu m in size. Furthermore, the synthesized porous composite has compressive strength \~ 11.8 +/- 1.5 MPa and modulus \~ 0.243 +/- 0.031 GPa, in the range of cancellous bone. Moreover, the nanocomposite provides favorable environment to cells for proliferation, high alkaline phosphatase (ALP) activity and extracellular mineralization. In vitro degradation of synthesized nanocomposites was tested in simulated body fluid. Results ascertained that the synthesized porous hydroxyapatite nanocomposite would be a promising scaffold for bone tissue engineeri
Synthesis of novel p-n-p BiOBr/ZnO/BiOI heterostructures and their efficient photocatalytic performances in removals of dye pollutants under visible light
No full textVarious photocatalysts were synthesized through deposition of BiOBr and BiOI on ZnO in the present research. The formation of heterostructures was studied by different instruments. The photocatalytic performances were studied by degrading different dyes, as water contaminants. The results showed that the ternary BiOBr/ZnO/BiOI (20 %) heterostructure has excellent photocatalytic ability in degradations of methylene blue, fuchsine, rhodamine B, and methyl orange, which was about 12.5, 41.5, 59, and 75-folds as high as the pristine ZnO, respectively. The increased photodegradation ability was ascribed to the more absorption of visible light, large specific surface area, and the construction of p-n-p heterojunctions at the interface of p-BiOBr, n-ZnO, and p-BiOI semiconductors. It was proved that the center dot O-2(-), OH center dot, and h(+) species play important roles in photocatalytic performances. In our opinion, this study provides a new procedure for fabrication of efficient p-n-p heterojunction photocatalysts based on ZnO, which could solve environmental problems