IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Influence of additive contents on the properties of SiC ceramic membranes and their performance in oil-water separation
No full textThe high processing cost is the key challenge for the economic industrial use of SiC membrane The aim of this research was to fabricate mullite bonded porous SiC ceramic membrane at low temperature from novel combinations of fly ash and alumina (FA) in weight ratio 44.5:55.5 as sintering additives. The influences of FA and pore former content on the porosity, morphology, crystalline phase composition, mechanical performance, permeability properties were investigated. The membrane prepared at 1300 degrees C using 20 wt% FA showed pure water permeability 3690 Lm(-2)h(-1)bar(-1) and exhibited high oil removal efficiency of similar to 98% from the synthetic oil-water emulsion having oil concentration of 1000 mg/L. The corrosion behaviour of silicon carbide membrane in the strong acid and alkali solution and its mechanism were investigated. The utilization of fly ash successfully reduced the raw material cost and sintering temperature and the use of alumina reduced the amount of oxidation of SiC as well as increased the amount of mullite bond phase which resulted excellent mechanical strength to the final ceramics
Synthesis and characterization of Yb3+activated Lu2O3 nanoparticles doped optical fiber preform for high power laser application
No full textYb3+-activated Lu2O3 is known to exhibit excellent thermal conductance, which can be a potential candidate to develop high-power laser fiber. Here we report the synthesis of Yb3+-activated Lu2O3 nanoparticles following the homogeneous coprecipitation method along with their material and optical characterization. Five different samples were synthesized using different concentrations of Cetyl Trimethyl Ammonium Bromide (CTAB) as a cationic surfactant, Yb-Lu ratio in the presence/absence of aluminium (Al) as an additional dopant, followed by calcination at different temperatures. Differential thermal analysis (DTA) and thermogravimetry (TG) analysis were performed to optimize the thermal annealing condition while the X-ray diffraction (XRD) analysis shows the formation of a pure bixbyite structure with an average particle size of -15 nm at 800 degrees C that reaches up to -120 nm with increasing calcination temperature to 1400 degrees C. The field emission scanning electron microscope (FESEM) analysis shows nearly cubic morphology while high-resolution Transmission Electron Microscope (HRTEM) analysis confirms the crystalline nature and the average particle size corroborates with the XRD analysis result. The developed nanoparticle was found to exhibit characteristics of Yb-absorption and emission peaks showing no interference with Lu2O3. The emission intensity and fluorescence lifetime of the Yb3+-activated Lu2O3 nanoparticles were found to depend on the Yb concentration, average particle size, and presence of aluminium as a co-dopant. To evaluate the practical application of the developed nanoparticles, an optical preform is developed using synthesized nanoparticles as Yb-source through modified chemical vapor deposition (MCVD) coupled with solution doping (SD) technique and the initial performance of the preform is also reported
Role of Efficient Charge Transfer at the Interface between Mixed-Phase Copper-Cuprous Oxide and Conducting Polymer Nanostructures for Photocatalytic Water Splitting
No full textPhotocatalytic hydrogen generation from water splitting is regarded as a sustainable technology capable of producing green solar fuels. However, the low charge separation efficiencies and the requirement of lowering redox potentials are unresolved challenges. Herein, a multiphase copper-cuprous oxide/polypyrrole (PPy) heterostructure has been designed to identify the role of multiple oxidation states of metal oxides in water reduction and oxidation. The presence of a mixed phase in PPy heterostructures enabled an exceptionally high photocatalytic H-2 generation rate of 41 mmol h(-1) with an apparent quantum efficiency of 7.2% under visible light irradiation, which is a 7-fold augmentation in contrast to the pure polymer. Interestingly, the copper-cuprous oxide/PPy heterostructures exhibited higher charge carrier density, low resistivity, and 6 times higher photocurrent density compared to Cu2O/PPy. Formation of a p-p-n junction between polymer and mixed-phase metal oxide interfaces induce a built-in electric field which influences directional charge transfer that improves the catalytic activity. Notably, photoexcited charge separation and transfer have been significantly improved between copper-cuprous oxide nanocubes and PPy nanofibers, as revealed by femtosecond transient absorption spectroscopy. Additionally, the photocatalyst demonstrates excellent stability without loss of catalytic activity during cycling tests. The present study highlights a superior strategy to boost photocatalytic redox reactions using a mixed-phase metal oxide in the heterostructure to achieve enhanced light absorption, longer charge carrier lifetimes, and highly efficient photocatalytic H-2 and O-2 generation
Nanoscale borosilicate bioactive glass for regenerative therapy of full-thickness skin defects in rabbit animal model
No full textBioactive glass (BG) occupies a significant position in the field of hard and soft tissue regeneration. Different processing techniques and formulas have been introduced to expand their regenerative, angiogenic, and antibacterial properties. In the present study, a new formula of bborosilicate bioactive glass nanofibers was prepared and tested for its wound-healing efficacy in a rabbit animal model. The glass formula ((1-2) mol% of B2O3 (68-69) mol% of SiO2, and (29-30) mol% of CaO) was prepared primarily by the sol-gel technique followed by the electrospinning technique. The material was characterized for its ultrastructure using scanning electron microscopy, chemical composition using FTIR, and its dynamic in vitro biodegradability using ICP-AES. Twelve rabbits were subjected to surgical induction of full-thickness skin defects using a 1 cm(2) custom-made stainlessteel skin punch. The bioactive glass nanofibers were used as a grafting material in 6 experimental rabbits, while the defects in the remaining rabbits were considered as the negative control samples. All defects were assessed clinically for the decrease in wound size and clinical signs of healing and histologically for angiogenesis, collagen density, inflammatory response, cell recruitment, epithelial lining, and appendages at 1,2 and 3 weeks following the intervention. Structural analysis of the glass fibers confirmed their nano-size which ranged from 150 to 700 nm. Moreover, the chemical analysis confirmed the presence of SiO2 and B2O3 groups within the structure of the nanofibers. Additionally, dynamic biodegradation analysis confirmed the rapid degradation of the material starting from the first 24 h and rapid leaching of calcium, silicon, and boron ions confirming its bioactivity. The wound healing study of the nanofibrous scaffold confirmed its ability to accelerate wound healing and the closure rate in healthy rabbits. Histological analysis of the defects confirmed the angiogenic, regenerative and antibacterial ability of the material throughout the study period. The results unveil the powerful therapeutic properties of the formed nanofibers and open a new gate for more experimental and clinical applications
PVDF based flexible magnetoelectric composites for capacitive energy storage, hybrid mechanical energy harvesting and self-powered magnetic field detection
No full textHere we develop YFeO3-poly(vinylidene fluoride) (YFO-PVDF) based composite systems (with varied concentration of YFO in PVDF) and explore their multifunctional applicability including dielectric, piezoelectric, capacitive energy storage, mechanical energy harvesting, and magnetoelectric performances. The 5 wt% YFO loaded PVDF (5 YF) film has exhibited the highest polar phase percentage of -85%. On the other hand, the study of energy storage performance has shown the highest energy storage density for 3 wt% YFO loaded PVDF (3 YF) film. Owing to its highest polar phase and space charge polarization, the 5 YF film has shown the highest mechanical energy harvesting performance with open circuit voltages of -10 and 74 V and power densities of -2 and 47 & mu;W/cm2 from the corresponding piezoelectric and piezo-tribo hybrid devices, respectively. The fabricated composite films have also shown good magnetoelectric (ME) properties with an ME coupling coefficient (& alpha;33) of -5.2 mV cm-1 Oe- 1 (at 1 kHz frequency and 0.8 kOe applied DC field) for the poled 5 YF film. The application of an external magnetic field has shown the ability to tune the mechanical energy harvesting performances of both the piezoelectric and piezo-tribo hybrid devices which suggests their future application in self-powered magnetic field sensing
Highly Sensitive and Wearable ZnO-Graphene Nanocomposite-Based Strain Sensors for Human Motion Detection
No full textFlexible electronic sensors have garnered considerable interest in wearable health-monitoring devices and electronic skin. In this work, a simple method for the fabrication of flexible zinc oxide-graphene nanoplatelet (ZnO-GNP) nanocomposite-based strain sensors has been proposed. The sensing element was deposited on the polydimethylsiloxane (PDMS) substrate by a facile spin and peel strategy to yield flexible sandwiched sensors. The effect of varying the blending ratio of the constituents on the electromechanical responses of the sensors was studied. The sensors exhibited high stretchability, good sensitivity, high reversibility, and superior stability under tensile and bending loads. The flexible nanocomposite sensors were able to detect extensive human movements such as bending of the elbow, wrist, and finger and also subtle motions such as eye blinking, wrist pulse, and phonation. Owing to the facile and economical fabrication method, high sensitivity, and good reversibility, the ZnO-GNP sensors have a high prospect of application in wearable health-monitoring devices, robotics, and various forms of human-machine interface
Local delivery systems of drugs/biologicals for the management of burn wounds
No full textSevere burn injuries are one of the major challenging health issues and pertain to significant morbidity and mortality due to their extensive traumatic and physiological damage to the organs. For decades, crucial steps and procedures have been considered to comprehend burn management. Early debridement and graft application are common practices that have improved the conditions and outcomes of burn patients physically and cosmetically. However, many drawbacks are still arising while managing burn treatment. Delayed healing, scarring, infection, and pain are among the reasons. Moreover, it is necessary to overstep to bring up new techniques and medications for improved healing quality. In this present article, we review and discuss the latest treatment of burn wound management and treatment. This review aims to provide a comprehensive discussion of the use of antibiotics and metallic ions for local delivery at wound sites and also provides a thorough briefing of the mechanism of action of these therapeutic agents. Furthermore, this article also provides an overall scenario of burn wound management, different regulations, and the advancement of nanotherapeutics for burn wound management and novel strategies developed in the past decades. Overall, this review article primarily targets to provide the scientific community with some settler ideas and research advancements, that improve and uplift burn wound care with a focus on infections, scarring, drug deliveries, nanomaterial, growth factors, bioactive proteins, and tissue engineering
Structure-Dependent Corrosion Behavior of Electrodeposited Zn Coating
No full textIn the present work, zinc (Zn) coating was developed on an interstitial-free (IF) steel from Zn sulfate bath using direct current (DC) and pulse current (PC) electrodeposition techniques at different current densities of 10, 30, and 60 mA/cm(2). The x-ray diffraction (XRD) analysis of the coatings reveals that the higher atomically dense (0002) crystal plane of the pure Zn in the PC deposits is pronounced as compared to the DC deposits. The scanning electron microscopic (SEM) study displays finer and compact morphology of the PC deposits as compared to the DC deposits. The electrodeposits change from coarser to finer morphology with an increase in current density in both the electrodeposition techniques. All the PC deposits show a higher water contact angle (WCA) as compared to the DC deposits at each applied current density. The finer and compact coating morphology, higher WCA values with the dominance of a higher atomically dense (0002) crystal plane as well as the higher fraction of simonkolleite phase lead to the higher corrosion resistance of the PC deposits than the DC deposits
kHz pulse generation with Brillouin erbium fiber laser
No full textNarrow linewidth light lasers are critical for many applications including quantum computing, spectroscopy, and sensing. Stimulated Brillouin scattering is a promising approach to realize highly coherent light laser emission. Here we report demonstration of a pulsed Brillouin erbium fiber laser (BEFL) operating at kHz regime. The BEFL operates at 1550.1 nm, which is upshifted by 0.09 nm from the Brillouin pump wavelength as the erbium-doped fiber was pumped above the threshold of 24.8 mW. It has a peak power of -8.4 dBm with a side-mode suppression ratio of 32 dB at 980 nm pump power of 70.5 mW. At 24.8 mW pump, the BEFL produced a pulse train operating at 12.57 kHz due to the inherent instability in relaxation oscillation, which causes the nonlinear self-pulsing mechanism in the BEFL cavity. The pulse rate increased to 77.11 kHz. As the pump power is raised to 36.2 mW. However, the more than one pulses were generated as the pump power is further increased. This is the first demonstration of a stable kHz pulse generation in BEFL cavity. The laser system is simple, compact and in all-fiber configuration
Effect of cold working on the rate sensitivity in high entropy lamellar CoCrFeNi(Nb-x/Ta-y) eutectic composites
No full textThe strain rate sensitivity (m) and the activation volume (V*) of arc melted ingots (AMIs), suction cast rods (SCRs) of lamellar CoCrFeNiNbx (0.45 <= x <= 0.65) and CoCrFeNiTay (0.2 <= y <= 0.5) eutectic high entropy alloys (EHEAs) comprising of FCC gamma-Ni and Fe2Nb/Co2Ta-type Laves phases have been studied at strain rates of 8 x 10(-5)- 8 x 10(-3)/s. Furthermore, specimens were cold worked up to 55% strain to investigate the effect of prior deformation on the rate sensitivity in bulk specimen using jump test under compression as well as the localized m in the nanoeutectic matrix and micrometer-size pro-eutectic phases using nanoindentation. The m value of the bulk EHEAs with varying lamellae thickness (lambda(w)) of 70-202 nm lies in between 0.0070 and 0.0082, and the V* value lies in between 24.8b(3) and 43.7b(3). Whereas, the localized m value of the eutectic matrix increases from 0.0066 to 0.0075 upon cold working of x = 0.5 SCR. Cold working increases the dislocation density up to 10(16)/ m(2), forms cells, sub-boundaries and distorts the lamellae interface, thus reducing the dislocation mean free path (Lambda) and V*. The local lattice distortion, lamellae thickness, and the dislocation pile-up at the lamellae interface are correlated with the rate sensitivity and related mechanisms in the solute concentrated EHEAs