IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Engineering Vascularizing Electrospun Dermal Grafts by Integrating Fish Collagen and Ion-Doped Bioactive Glass
No full textUtilizing bioactive molecules from organic sources in combination with inorganic materials for enhanced tissue regeneration has been a focus of recent scientific advancements. Some recent studies showed the potential of some specialized bioactive glass for healing of soft tissues; the role of Rohu (Labeo rohita) skin-derived collagen, a biopolymer in tissue regeneration and cutaneous healing, is yet to be established. So, we have fabricated four different types of electrospun mats as wound dressing materials/dermal grafts by combining locally sourced fish (Rohu) skin-derived collagen with novel composition of bioactive glass (Fcol/BAG) without and with dopants (3% and 5% Cu and Co, respectively and their binary) aimed at achieving an accelerated wound healing. FTIR and EDX mapping indicated successful integration of collagen and ion-doped bioactive glass in electrospun mats. Microfibers' architectural features and composition provided a cytocompatible and nontoxic environment conducive to adhesion, spreading, and proliferation of human dermal fibroblasts in vitro; in addition, they were hemocompatible with rabbit red blood cells. Better cutaneous wound healing in rabbits was achieved by treating with Fcol/CoBAG and Fcol/CuCoBAG microfibers with respect to improved wound closure, well-formed continuous epidermis, higher wound maturity, and regulated deposition of extracellular matrix components; mature collagen and elastin. Notably, a significantly (p < 0.01) higher density of blood vessels/positive CD 31 staining was observed in fish collagen/ion-doped bioactive glass microfibrous mat treated wounds suggesting efficient neo-vascularization during early stages of the healing process particularly attributable to copper and cobalt ions in the doped bioactive glass. Enhanced vascularizing ability of these engineered dermal composite grafts/wound dressings along with efficient remodeling of cutaneous structural components (ECM) could collectively be ascribed to bioactive properties of bioactive glass and stimulatory roles of copper, cobalt ions, and fish collagen. Our study demonstrates that a fish collagen/Cu and Co-doped bioactive glass microfibrous mat could potentially be used as a low-cost dressing material/dermal graft for augmented cutaneous wound healing
Electronic structure and magnetic properties of 3d-4f double perovskite material
No full textDouble-perovskite-based magnets wherein frustration and competition between emergent degrees of freedom are at play can lead to novel electronic and magnetic phenomena. In this paper, we report the electronic structure and magnetic properties of an ordered double perovskite material, Ho2CoMnO6. In the double perovskites with general class A(2)BB'O-6 (A = rare-earth ions; B, B' = transition metal ions), the octahedral B and B' sites have a distinct crystallographic site. The Rietveld refinement of x-ray diffraction data reveals that Ho2CoMnO6 crystallizes in the monoclinic P2(1)/n space group. X-ray photoelectron spectroscopy confirms the charge state of cations present in this material. The temperature dependence of magnetization and specific heat exhibits a long-range ferromagnetic ordering at T-c similar to 76 K owing to superexchange interaction between Co2+ and Mn4+ moments. Furthermore, the magnetization isotherm at 5 K shows a hysteresis curve that confirms the ferromagnetic behavior of this double perovskite. We observed a reentrant glassy state in the intermediate-temperature regime, which is attributed to inherent antisite disorder and competing interactions. A large magnetocaloric effect has been observed much below the ferromagnetic transition temperature. Temperature-dependent Raman spectroscopy studies support the presence of spin-phonon coupling and short-range order above T-c in this double perovskite. The stabilization of magnetic ordering and charge states is further analyzed through electronic structure calculations. The latter also infer the compound to be a narrow-band-gap insulator with the gap arising between the lower and upper Hubbard Co d subbands. Our results demonstrate that antisite disorder and complex 3d-4f exchange interactions in the spin lattice account for the observed electronic and magnetic properties in this promising double perovskite material
Gated Photodetector with a Bipolar Response from Single-Crystal Halide Perovskite Using a Polymeric Electrolyte as the Gate Dielectric
No full textIn this report, we show that a gated optical detector working in the visible wavelength region can be made on single-crystal halide perovskite methylammonium lead bromide (CH3NH3PbBr3 or MAPB). A polymeric electrolyte (PEO/LiClO4) is used as the gate dielectric, which forms an electric double layer (EDL) at the electrolyte/MAPB interface, leading to high specific gate capacitance and enabling enhanced carrier induction at a low gate bias. The photoresponse of the detector can be enhanced significantly by a large factor (e.g., by a factor of 35) by a bias V-g of 10 V. The core gate operation is due to the field effect, and the detector shows the characteristics of a field effect transistor (FET) with bipolar nature, thereby operating with both polarities of the gate bias. This is enabled by the special feature of halide perovskites, that is, they have appreciable mobility for both types of carriers. It is established that the enhancement of the detector current response occurs due to the synergy of carriers created by illumination as well as the gate when they are present simultaneously, which modifies the near-band-edge trap states close to valence band maxima (VBM) and conduction band minima (CBM) and enhances the carrier mobility. The proposed synergy mechanism is validated by the gate-induced enhancement of the photoluminescence (PL) emission intensity and narrowing of the emission line
Design and fabrication of a tapered fiber bundle for a pump combiner with a uniform splicing region
No full textA process of fabricating tapered fiber bundle (TFB) consisting of a set of input pump fibers, stacked inside a low-OH silica capillary, has been optimized to combine multiple multimode pump powers into different output fibers having cladding diameters of 400, 250, and 125 AM. Instead of individual input and output fiber processing, here pump combiner fabrication is based on the processing of the TFB to match its diameter with the output fiber to eliminate any perturbation in light guidance. Fabrication of the TFB includes multiple fusing steps and tapering with brightness conservation, followed by reduction of the outer silica layer through chemical etching to obtain the desired outer diameter. To reduce pump power leakage, the optimum fluorine cladding layer thickness outside the pump fiber cores and outer silica layer thickness have been estimated through numerical simulations using a finite element solver. The influence of fabrication parameters such as interstitial gaps between the input pump fibers, taper ratio, fluorine cladding, outer silica layer thickness, and non-uniformity of splicing region has been characterized in terms of transmission efficiency per port, as well as cumulative power handling along with the operating temperature at maximum power. (C) 2022 Optica Publishing Grou
Y and Al co-doped ZnO-nanopowder based ultrasensitive trace ethanol sensor: A potential breath analyzer for fatty liver disease and drunken driving detection
No full textExcess ethanol in exhaled breath can be an indicator of intoxication and a biomarker for fatty liver disease. Herein, we report for the first time a highly sensitive and selective Al and Y co-doped ZnO nanopowder sensor for the detection of trace ethanol in exhaled breath. The nanopowder was synthesized by a facile sol-gel method and characterized by multiple sophisticated techniques, viz. XRD, XPS, FTIR, FESEM, EDX, BET surface area analysis, UV-Vis spectroscopy, photoluminescence, infrared imaging, and current-voltage (I-V) measurement. The developed sensors, especially 5% Y and 1% Al co-doped ZnO exhibited excellent n-type response to 1 ppm ethanol (62.8%). Further, appreciable selectivity to trace ethanol with respect to other interfering gases, viz. acetone, ammonia, CO, NO, NO2, formalin, acetylene, and saturated moisture was observed. Additionally, ul-trafast response (0.77 s) and recovery (8.1 s) time, good repeatability, and long-term stability for at least 10 months were observed. Satisfactory resolution between healthy breath, and simulated breath with ethanol vapor excess was obtained. The optimized sensor could be very suitable for both the detection of liver problem as well as commercial breath ethanol analyzer for drunken driving detection
Shape dependent multiferroic behavior in Bi2Fe4O9 nanoparticles
No full textFerroelectric and magnetic properties are investigated for Bi2Fe4O9 nanoparticles with different shapes (cuboid and sphere-like) synthesized by hydrothermal and sol-gel method. The magnetic study reveals that coercivity, Neel temperature and remanent magnetization strongly depend on shape of the particle. The nanoparticle with sphere-like shape exhibits magnetization curve of antiferromagnetic (AFM) ordering with ferromagnetic (FM) component. As the particle shape changes from sphere-like to cuboid, the AFM component is dominating over the ferromagnetic component. A small exchange bias is also observed at low temperature in both the sphere-like and cuboid nanoparticle. The coercivity, remanent magnetization and Neel temperature of sphere-like nanoparticle is greater than cuboid nanoparticle. Ferroelectric measurement shows the remanent polarization of cuboid is greater than sphere-like nanoparticle but the coercivity is almost same. This Bi2Fe4O9 nanoparticle shows a small change in polarization under magnetic field. The polarization value decreases with magnetic field increases. The magnetoelectric coupling-measured by change of remanent polarization under magnetic field are found to be greater in Bi2Fe4O9 sphere-like nanoparticles. These shape dependent magnetic and ferroelectric properties are coming because of shape anisotropy
Intercalation of montmorillonite with dialkylammonium cationic surfactants
No full textThree montmorillonite (Mt) clays with different cation exchange capacity (CEC) were intercalated by a series of dialkyl ammonium cations with carbon numbers (Nc= ) 8, 10, 12 and 18 in each alkyl chain. The intercalated clays were characterized by X-ray Diffraction, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy and Transmission Electron Microscopy. The basal spacing of intercalated Mts in-creased gradually with increasing chain length. Interlayer arrangement of dialkyl surfactant cations in the intercalated clay gallery changed from flat bilayer to paraffinic and reached as high as 3.57 nm for the highest CEC clay intercalated with cations having Nc= 18 in each alkyl chain. For dialkylammonium inter-calants, the increase in basal spacing was predominantly guided by the intercalant's structure and organic loading values lacked such direct correlation. Mt with low CEC showed large expansion in the clay inter-layer with increasing alkyl chain length even with marginal increment in the organic loading. The highest basal spacing was observed always with the highest CEC clay for every intercalant irrespective of alkyl chain length. The wide expansion of clay gallery for the longest dialkyl intercalant in this series for all clays might be attributed to presence of intercalated surfactant molecules along with physically adsorbed surfactant cations in the clay interlayer. The change in conformations of intercalated dialkyl ammonium intercalants with increasing alkyl chain length was analyzed from FTIR study. With increasing alkyl chain length, methylene symmetric and asymmetric stretching frequency shifted to lower wavenumber for all Mt clays-which indicated greater ordered conformations obtained with increasing alkyl chain length.(C) 2022 Elsevier B.V. All rights reserved
A nonenzymatic reduced graphene oxide-based nanosensor for parathion
Get PDFOrganophosphate-based pesticides (e.g., parathion (PT)) have toxic effects on human health through their residues. Therefore, cost-effective and rapid detection strategies need to be developed to ensure the consuming food is free of any organophosphate-residue. This work proposed the fabrication of a robust, nonenzymatic electrochemical-sensing electrode modified with electrochemically reduced graphene oxide (ERGO) to detect PT residues in environmental samples (e.g., soil, water) as well as in vegetables and cereals. The ERGO sensor shows a significantly affected electrocatalytic reduction peak at -0.58 V (vs Ag/AgCl) for rapid quantifi-cation of PT due to the amplified electroactive surface area of the modified electrode. At optimized experimental conditions, square-wave voltammetric analysis exhibits higher sensitivity (50.5 mu A center dot mu M-1 center dot cm(-2)), excellent selectivity, excellent stability (approximate to 180 days), good reproducibility, and repeatability for interference-free detection of PT residues in actual samples. This electro-chemical nanosensor is suitable for point-of-care detection of PT in a wide dynamic range of 3 x 10(-11)-11 x 10(-6) M with a lower detection limit of 10.9 pM. The performance of the nanosensor was validated by adding PT to natural samples and comparing the data via absorption spectroscopy. PT detection results encourage the design of easy-to-use nanosensor-based analytical tools for rapidly monitoring other environmental samples
Q-Switched Fiber Laser with a Hafnium-Bismuth-Erbium Codoped Fiber as Gain Medium and Sb2Te3 as Saturable Absorber
No full textWe successfully demonstrate Q-switched fiber laser with a 20 cm long Hafnium-Bismuth-Erbium codoped fiber (HBEDF) as an active medium in conjunction with Antimony Telluride (Sb2Te3) saturable absorber (SA). The HBEDF has an Erbium ion absorption coefficient of 100 dB/m at 980 nm; thus, the laser setup only requires a very short length of gain medium for lasing in the 1550 nm range. We realize the Sb2Te3 SA obtained by embedding the material into Polyvinyl Alcohol (PVA), and a Q-switched pulse train operating at 1560.7 nm is realized, using only a 20 cm long active fiber, when the prepared Sb2Te3 thin film is integrated into the laser ring cavity. The repetition rate of the Q-switched pulses is tunable from 47.7 to 74.8 kHz as the pump power is raised from the threshold value equal to 69.9 mW to a value of 105.0 mW. The maximum attainable pulse energy is 31.2 nJ. Our results indicate that the Sb2Te3 material is useful as an effective Q-switcher especially for the laser operation in 1.55 mu m range
Interpreting the optical properties of oxide glasses with machine learning and Shapely additive explanations
No full textDue to their excellent optical properties, glasses are used for various applications ranging from smartphone screens to telescopes. Developing compositions with tailored Abbe number (V-d) and refractive index at 587.6 nm (n(d)), two crucial optical properties, is a major challenge. To this extent, machine learning (ML) approaches have been successfully used to develop composition-property models. However, these models are essentially black boxes in nature and suffer from the lack of interpretability. In this paper, we demonstrate the use of ML models to predict the composition-dependent variations of V-d and n(d). Further, using Shapely additive explanations (SHAP), we interpret the ML models to identify the contribution of each of the input components toward target prediction. We observe that glass formers such as SiO2, B2O3, and P2O5 and intermediates such as TiO2, PbO, and Bi2O3 play a significant role in controlling the optical properties. Interestingly, components contributing toward increasing the n(d) are found to decrease the V-d and vice versa. Finally, we develop the Abbe diagram, using the ML models, allowing accelerated discovery of new glasses for optical properties beyond the experimental pareto front. Overall, employing explainable ML, we predict and interpret the compositional control on the optical properties of oxide glasses