IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Role of Sodium-Ion Dynamics and Characteristic Length Scales in Ion Conductivity in Aluminophosphate Glasses Containing Na2SO4
No full textAchieving high ion conductivity in glass-based Na-ion conducting materials for their applications as solid electrolytes in batteries is still challenging owing to the vague knowledge on the factors governing Na-ion dynamics. In the present study, an attempt has been made to identify the factors affecting the sodium-ion dynamics through structure and conductivity property correlation for the 37.5Na(2)O-37.5P(2)O(5)-15Al(2)O(3)-10NaF (FS-0; mol %) glass system with varied concentrations of Na2SO4. P-31, Al-27, and Na-23 MAS NMR (magic-angle spinning nuclear magnetic resonance) and Raman spectroscopy are employed to assess the structural modifications, and impedance spectroscopy is used to measure the variations in ionic conductivity on the addition of Na2SO4 in the FS-0 glass. Raman spectra and MAS NMR analysis indicate that the quantity of P-O-Na bonds and sulfate (SO42-) units surrounded by sodium increase with increasing Na2SO4 concentration. Impedance analysis reveals that the conductivity of FS-0 glass enhances by 1 order with the addition of 6 mol % Na2SO4. We identify from the ac-conductivity spectral analysis that the concentration of charge carriers and the critical hopping length of mobile cations increase with the addition of 6 mol % Na2SO4. Overall, we reveal that the structural modifications, Na-ion concentration, and the shallower potential well that is created for sodium due to its interaction with the nearest neighboring cations affect the Na-ion dynamics. The information obtained from the present study certainly helps to optimize the chemical composition of glasses demonstrating high ionic conductivity
Synthesis and characterizations of sugar-glass nanoparticles mediated protein delivery system for tissue engineering application
No full textThe present work focuses on the synthesis and characterization of a sugar-glass nanoparticle (SGnP) based reservoir type protein delivery system pertinent to tissue engineering applications. The SGnP nanocarriers were prepared via inverse micelle of sodium bis(2-ethylhexyl) sulfosuccinate based on an anionic surfactant and subsequent flash-freezing technique. Initially, a total of five different grades of protein-free SGnPs have been prepared to examine the effects of systematic changes in starting concentrations of the aqueous phase, organic solvent, the molar ratio of water, and surfactant in controlling the size, shape, and uniformity of micelles. Evidently, the Fourier transform infrared (FTIR) and scanning electron microscope (SEM) results confirmed that the SGnP can be successfully prepared. Subsequently, SGnP based protein depot has been validated using bovine serum albumin (BSA), horseradish peroxidase (HRP) and growth and differentiation factor-5 (GDF-5). The particle size, morphology, protein encapsulation efficiency and in vitro release kinetics were assessed using SEM, FTIR, UV-visible spectroscopy and Bradford protein assays. Excellent encapsulation efficiency (93%-94%) and sustained release behaviour of BSA (similar to 22% protein release after 14 d) and GDF-5 proteins (similar to 29% protein release after 30 d) were exhibited by the optimal grades of SGnP constructs with an average particle size of 266 nm and 93 nm, respectively. Furthermore, FTIR, differential scanning calorimeter (DSC), polyacrylamide gel electrophoresis (PAGE) and NATIVE-PAGE studies results confirm successful encapsulation, stability and preserving the structural integrity of proteins placed into the core of the SGnP constructs. Evidently, a very high (93%) residual HRP enzyme activity signifies the capability of our SGnP system to protect the encapsulated proteins from process-related stresses. In vitro cytotoxicity and fluorescence cell morphology analyses using human adipose-derived mesenchymal stem cells affirmed good cytocompatibility of protein encapsulated SGnP. Overall, the study findings indicate SGnP nanocarrier-mediated protein delivery systems as a promising approach complementary to conventional techniques in tissue engineering and therapeutic applications
Paperator: The Paper-Based Ceramic Separator for Lithium-Ion Batteries and the Process Scale-Up Strategy
No full textDue to its flexibility, cost-effectiveness, and natural abundance, paper has become a material of choice for its targeted applications in electronic and optoelectronic devices. With an aim to develop a paper-based ceramic separator (henceforth will be referred to as paperator), a low-cost paper substrate sourced from the local market has been functionalized by the wet-coating method using duo-polymer (chitosan and polyvinyl alcohol) and ceramic (BaTiO3) nanopowder. The developed paperator shows excellent air permeability, improved thermal stability of up to 200 degrees C without dimensional shrinkage, quicker wettability to an electrolyte, and comparable electrochemical performance to that of polypropylene-based commercial separator. The modification of the paper substrate using polymer and ceramic particles has also improved the tensile strength of the paperator to a maximum value of 45.23 MPa w.r.t. 28.20 MPa for pristine paper. The electrochemical performance of the developed paperators shows satisfactory cell performance at different current densities with excellent coulombic efficiency and comparable discharge capacities with that of a commercial separator. Compared to the commercial PP-based membrane, slightly lowered discharge capacities are obtained from the cells fabricated with developed paperators, which may primarily be due to the higher thickness (60/70 mu m) and cellulosic tortuosity. Electrochemical performances of the developed ``paperators'' were also evaluated for use in supercapacitors (SCs) by fabricating SC cells and their testing as per IEC 62391-1, which showed the cell capacitance and ESR values of 17.2 +/- 0.8 F and 76 +/- 3 m Omega, respectively, and the results were also compared with those of commercial cellulose-based paper separators. Based on the R&D achievements, the present study has also been extended for a scale-up strategy to produce a paper-based separator in roll form, where a ``paperator'' of 60 mm in width in a continuous manner has been fabricated by using in-house-designed semi-automated double-decker separator fabricator machine
Fabrication of ultra-high numerical aperture GeO2-doped fiber and its use for broadband supercontinuum generation (vol 56, pg 9315, 2017)
No full textThis publisher's note serves to correctAppl. Opt.56, 9315 (2017). (C) 2022 Optica Publishing Grou
Supramolecular Arrangement and DFT analysis of Zinc(II) Schiff Bases: An Insight towards the Influence of Compartmental Ligands on Binding Interaction with Protein
No full textWe report, for the first time, a detailed crystallographic study of the supramolecular arrangement for a set of zinc(II) Schiff base complexes containing the ligand 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol], where R=methyl/tert-butyl/chloro. The supramolecular study acts as a pre-screening tool for selecting the compartmental ligand R of the Schiff base for effective binding with a targeted protein, bovine serum albumin (BSA). The most stable hexagonal arrangement of the complex Zn-Me] (R=Me) stabilises the ligand with the highest FMO energy gap (Delta E=4.22 eV) and lowest number of conformations during binding with BSA. In contrast, formation of unstable 3D columnar vertebra for Zn-Cl] (R=Cl) tend to activate the system with lowest FMO gap (3.75 eV) with highest spontaneity factor in molecular docking. Molecular docking analyses reported in terms of 2D LigPlot+ identified site A, a cleft of domains IB, IIIA and IIIB, as the most probable protein binding site of BSA. Arg144, Glu424, Ser428, Ile455 and Lys114 form the most probable interactions irrespective of the type of compartmental ligands R of the Schiff base whereas Arg185, Glu519, His145, Ile522 act as the differentiating residues with Delta G=-7.3 kcal mol(-1)
Studies on the Reaction Sintering of Magnesium Aluminate Spinel: Effect of Sintering Additives
No full textBroadband ASE source for S plus C plus L bands using hafnia-bismuth based erbium co-doped fibers
No full textA broadband amplified spontaneous emission (ASE) source is demonstrated experimentally by using hafnia-bismuth based erbium co-doped fibers (HB-EDFs) with a total length of 200-cm as an active medium. Both of parallel and series configurations are used to generate a broadband ASE source, operating at 1.5 mu m and that cover S-, C-, and L-bands. The comparison proves that the series configuration provides a relatively larger ASE bandwidth, higher output power, higher efficiency, and lower complexity. At the optimum total pumping power of 280 mW, a broadband ASE source of 57 nm with a power ripple of +/- 7.5 dB is achieved. Besides, a total ASE power of 20.8 mW is obtained, which is equivalent to 7% of the pumping efficiency
Study on the role of rGO in enhancing the electrochromic performance of WO3 film
No full textIn the present work, an improved electrochromic thin film has been developed with faster color switching time on incorporation of rGO in WO3 film. Here, pristine WO3 and rGO-WO3 (rGO concentration varying from 1-7wt %) based nanocomposite electrochromic films were fabricated on ITO coated glass substrate, by utilizing a facile sol-gel dip-coating technique. Detailed structural and morphological analyses of the films were carried out using XRD, FESEM, TEM and Raman Spectroscopy. Assimilating the electrochromic properties of all the films showed that, 5wt% rGO incorporated WO3 film gave a maximized electrochemical performance with minimum degradation in optical transmittance. The film also exhibited an optical modulation of similar to 50% and a better switching response having coloration time (t(c)) similar to 5.3 s and bleaching time (t(b)) similar to 6.2 s as compared to the pristine film (t(c) similar to 9.6 s, t(b) similar to 10.4 s). Incorporation of rGO also resulted in an enhancement of coloration efficiency from similar to 81 to similar to 386 cm(2)/C. The Electrochemical Impedance Spectroscopy (EIS) analysis of pristine and rGO loaded film clearly revealed better charge transfer on incorporation of rGO. The cyclic stability study exhibited similar to 25% deterioration in optical transparency of the bare WO3 film which was < 10% for the rGO impregnated film. An ex-situ XRD analysis demonstrated that a crystal dislocation occurring in pristine WO3 sample was responsible for the same
Dopant-mediated surface charge imbalance for enhancing the performance of metal oxide chemiresistive gas sensors
No full textChemically pristine and untailored metal oxide-based gas sensors usually suffer the brunt of poor sensitivity and selectivity. Doping with a suitable element is an efficient strategy to overcome the above challenges. However, to date, the choice of the dopant has been made primarily on empirical basis. This reflects the existence of lack of a general understanding as to what defines the suitability of a dopant. Based on surface electronic state analyses in different cases of dopant-enhanced gas sensing by tin oxide-based systems, we could identify a correlation between the role of the dopant oxidation states for generating surface charge imbalance and improvement in their respective sensing performances. The above studies were then extended to 54 different cases of dopant-induced sensing improvement in metal oxide-based systems and a similar correlation was observed. Based on the above observations, a generalized picture has been drawn that categorically delineates the role of surface charge imbalance in improved gas sensing performance. The above understanding is expected to make the choice of dopant more specific, paving the way for the development of highly sensitive gas sensors
Investigations on the add-layer sensitivity near mode transition of a stretched mode long period fiber grating
No full textThe influence of the spectral separation between two consecutive resonant cladding modes of long period fiber grating (LPFG) on the add-layer sensitivity around mode transition (MT) has been investigated with a view to enumerating the dependency of the sensitivity on the separation between the resonant wavelengths of cladding modes. The separation between two consecutive resonant modes was increased or stretched by etching, and the specific mode of interest was brought to the MT region by the deposition of electrostatic self-assembled (ESA) layers of polymeric material on the sensor surface. The add-layer sensitivity of the mode-stretched LPFG (MSLPFG) operating around the linear part of the MT region was found to be similar to 2.59 nm(WL)/nm(TH). The result was found to be superior almost by 1.7 times as compared to a similar LPFG sensor at MT, but without mode stretching. Theoretical modelling has also been shown to corroborate the experimental results