IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Indigenously developed CuO/TiO2 coated ceramic ultrafiltration membrane for removal of emerging contaminants like phthalates and parabens: Toxicity evaluation in PA-1 cell line
No full textEmerging contaminants like phthalates and parabens in pharmaceuticals and personal care products pose threat to humans and environment because they are endocrine disruptors and are persistent in nature. Removal of these contaminants by conventional treatment methods has proven less effective in removing emerging contaminants. Ceramic ultrafiltration (UF) membrane developed indigenously from CuO/TiO2 nanoparticles effectively removed phthalates and parabens from synthetic systems (10-1000 ppb concentration) with removal efficiency of >99%. FTIR (Fourier Transform Infrared Spectroscopy) analysis suggested surface adsorption of phthalate and paraben on UF membrane. The effect of different parameters, viz. Transmembrane pressure (TMP), time, feed concentration on membrane filtration efficiency, was calculated by response surface methodology (RSM). Cytotoxic effects of untreated and membrane treated phthalate and paraben solutions were observed on ovarian teratocarcinoma (PA-1) cell lines. Cytotoxicity was evaluated by cell toxicity and reactive oxygen species (ROS) generation in culture PA-1 cells. Results showed that concentration IC50 (half maximal inhibitory concentration) values for phthalate untreated and treated samples were 54.9 mu g/ml and 183.23 mu g/ml respectively while for paraben untreated and treated samples were 16.8 mu g/ml and 107.6 mu g/ml respectively
Modelling of nanoindentation behaviour in MgO doped alumina
No full textHere we report the modelling of the nanoindentation behaviour of 1-5 wt% MgO doped alumina ceramics. It is well-known that the nanoindetation technique is highly efficient in digging out the mechanical properties of various materials including ceramics especially, at small length scale. The samples prepared by the pressureless sintering technique are characterized by the x-ray diffraction, field emission scanning electron microscopy and the nanoindentation techniques. The experimental results obtained from the nanoindentation experiments exhibit a unique nanoindentation size effect as well as the occurrences of localized plasticity events. This unique observation is what drives the inspiration for modelling such behaviours. The modelling of this nanoindentation size effect identifies that it could be linked to the load dependent spatial variations in both the dislocation loop interaction zone size and the deformation resistance. The localized plasticity events are found to happen due to the simultaneous contributions from dislocation nucleation, localized shear deformation bands formation and microcracking formations. The critical loads at which localized plasticity events are initiated increase with the amount of MgO. It happens due to the simultaneous enhancements in the relative density, spinel phase, relative amount of fine grains, and decrease in average size of the fine grains. The implications of these observations for microstructural design of structural ceramics like alumina with enhanced contact deformation resistance at the nanoscale are also discussed
Effect of doping in hydroxyapatite as coating material on biomedical implants by plasma spraying method: A review
No full textHydroxyapatite (HAp) is still one of the most widely used bioactive coating material to metallic implant in orthopedic fields because of its good biocompatibility, chemical and structural resemblance to natural bone, osteoconductivity, coupled with quicker implant fixation and strong bonding between living bone with implants. Many techniques are used to deposit HAp as coating material on metallic implants among which plasma spray coating stands out as this process is cost effective, reliable, and protects surface of metal from wear and corrosion. Although, HAp is a smart choice as implant coating material, however, its medical application has been restricted because of the unfavorable mechanical properties like brittleness, weak fracture toughness and poor tensile strength. Further, HAp coated implants suffer from longer time period for remodeling, slow osseointegration rate and lack of antimicrobial effects/properties. Different methodologies have been adopted as surface modification techniques to increase mechanical as well as biological properties of HAp. Among those approaches use of dopants in HAp is a very efficient way for modification of properties. Therefore, aim of this review paper is to assemble information related to HAp coating by plasma spray technique on implants and discuss their advantages and limitations. The article also reports how addition of various doping ions into HAp can overcome these limitations by effecting structural, compositional, mechanical properties of HAp. Finally, it reports how the single, binary and multi ion dopants incorporation in the HAp structure can affect the properties which ultimately affect implant functionality when coated by plasma spraying method
Preparation of serum capped silver nanoparticles for selective killing of microbial cells sparing host cells
Get PDFFollowing access into the cell, colloidal silver nanoparticles exhibit generalized cytotoxic properties, thus appear as omnipotent microbicidal, but not suitable for systemic use unless are free of toxic effects on host cells. The AgNP-Serum-18 when prepared from silver nitrate, using dextrose as reducing and group-matched homologous serum as a stabilizing agent, selective endocytosis, and oxidative stress-dependent bio-functional damages to the host are mostly eliminated. For their bio-mimicking outer coat, there is the least possibility of internalization into host cells or liberation of excess oxidants in circulation following interaction with erythrocytes or vascular endothelial cells. The presence of infection-specific antibodies in the serum can make such nano-conjugates more selective. A potent antimicrobial action and a wide margin of safety for mammalian cells in comparison with very similar PVA-capped silver nanoparticles have been demonstrated by the in-vitro challenge of such nanoparticles on different microbes, human liver cell-line, and in-vivo study on mice model. This may open up wide-range therapeutic prospects of colloidal nanoparticles
Biological performance of metal metalloid (TiCuZrPd:B) TFMG fabricated by pulsed laser deposition
No full textThe aim of our study is to investigate the effect of boron with different ratios in Ti-Cu-Pd-Zr metallic glass (MG) matrix (Ti-Cu-Pd-Zr:B) fabricated by Pulsed Laser Deposition (PLD) for biomedical implants. The Ti based Thin Film Metallic Glasses (TFMGs) in combination with boron (in different atomic %) was assessed in attaining the combined properties, like outstanding corrosion resistant properties and good biocompatibility in this work. The disordered structure and amorphous nature of the Ti-Cu-Pd-Zr:B thin films systems were achieved by the PLD process and affirmed by XRD and transmission electron microscopy. The boron incorporation in the TFMG has been elucidated by XPS analysis. The boron containing films displays distribution of boron protuberances interleaved in the amorphous matrix was stated from SEM analysis. It is found that increase in atomic percentage of boron contents in TFMG results in the improvement in glass transition temperatures. The electrochemical parameters suggest better corrosion resistance and capabilities of passivity when boron percentage was increased in the film thereby preventing adverse biological reactions. TFMGs exhibited excellent hemocompatibility by preventing the platelet activation. MTT assay manifests increase in cell concentration with culture period on the TFMGs for the MC3T3-E1 preosteoblasts cells. Cell morphology was also studied which confirmed the viable state of the cells on the TFMG surfaces. The combination of such distinctive properties marks these TFMG systems as prospective aspirants for biomedical implants
Effect of oxide layer and the duration of exposure on the liquid metal corrosion mechanism of RAFM steel in molten Pb-Li
No full textThe long-term corrosion behavior of IN-RAFM steel in molten Pb-Li upto 10, 000 h of exposure was studied in a rotating disc corrosion test facility at 823 K. As-received IN-RAFMS material possessed an air-formed surface layer containing oxides of Fe, Ce and W. Precipitation of chromium carbides at the grain/lath boundaries of asreceived IN-RAFMS led to grain boundary attack by liquid Pb-Li during the initial ?Incubation Period? which depicted slow dissolution of surface oxides and lesser corrosion rate. Complete dissolution of oxide layer altered the corrosion mechanism from grain boundary attack to matrix dissolution thereby increasing the corrosion rate
Electromigration of oxygen and resistive state transitions in sub-micron width long strip of La0.85Sr0.15MnO3 connected to an engineered oxygen source
No full textOxygen electromigration studies have been carried out on long and submicron width strips of La0.85Sr0.15MnO3 (LSMO:0.15) film on LaAlO3 substrate with lithographically defined oxygen source created by local electrochemical oxidation. Electromigration by short duration current stressing leads to transition from a high resistance state (HRS) to a metastable low resistance state (LRS) that recovers back after a wait time (t(W)). Sustained current stressing beyond a critical current leads to irreversible RS transition to a stable LRS. The transition has an Arrhenius type temperature dependence with an activation energy similar to 0.45-0.55 eV. Heating suppresses the transition and RS vanishes at a temperature T-0 >= 375 K. It is suggested that the irreversible transition happens due to phase transition from a higher resistance Jahn-Teller distorted orthorhombic phase (O') to a undistorted orthorhombic (O) phase which have close proximity at room temperature in LSMO:0.15 and are sensitive to current induced hole doping
Emergence of large thermal noise close to a temperature-driven metal-insulator transition
No full textWe report that close to a Mott transition there is an emergence of large thermal noise (Sth) which occurs concomitantly with large correlated flicker noise (1/ noise) with significant non-Gaussian content. This was observed in films of NdNiO3 (thickness 15 nm) grown on crystalline SrTiO3 substrates with different crystallographic orientations that show a hysteretic transition from a high temperature metallic phase to a low temperature insulating phase in the temperature range 160 to 211 K depending on the substrate orientation and the heating and cooling cycle. The thermal noise, which is distinct from the flicker noise, deviates from the canonical Johnson-Nyquist value of 4kBTR as measured through the ratio zeta (T)(= Sth(T)4k(B)TR). The ratio. reaches a maximum value of zeta(M) at a temperature T* that is close to but distinct from the metal-insulator transition (MIT) temperature TMI. In all the films near T*, the scaled thermal noise maxima zeta(M) >> 1. The films were found to be largely strain relaxed with residual in-plane and out-of-plane strain as measured by x-ray reciprocal space mapping. It has been observed that the ratio T*/T-MI as well as zeta(M) have a close dependence on the in-plane-strain in the film. The enhanced thermal noise that occurs along with large correlated flicker noise both arise from slow kinetics of relaxation as established from temperature dependence of the correlation time (tau) that gets significantly larger in the temperature range around T *, reaching a maxima at T = T *. It has been proposed that the existence of large noise (both thermal and flicker noise) owes its origin to electronic phase separation (EPS) that exists near the MIT. A physical model has been suggested that EPS near MIT temperature can give rise to a sparse phase of nanometric small pockets of metallic phases (nanopuddles) that are surrounded by and embedded within the minority insulating phase. The nanopuddles act as a source of charge fluctuations and are coupled weakly to the majority metallic phase by tunneling through the layer of the minority insulating phase. Such isolated metallic nanopuddles can be Coulomb charged if the charging energy E-C >= k(B)T and can have slow relaxation of fluctuations acting as a source of large noise. It has been argued that the size distribution of the nanopuddles, their average size , as well as the temperature dependence of their number density Nd can determine the temperature T *
Enhanced dielectric, ferroelectric, energy storage and mechanical energy harvesting performance of ZnO-PVDF composites induced by MWCNTs as an additive third phase
No full textThe present work highlights an attempt of fabricating a nanocomposite by the addition of multi-walled carbon nanotubes (MWCNTs) as a third phase into flexible ZnO-poly(vinylidene fluoride) (ZnO-PVDF) composites. MWCNTs played a very important role in distributing ZnO fillers in the PVDF matrix more homogeneously and increased the connection capability. Enhancement of the piezoelectric phase, dielectric permittivity, ferroelectric polarization, energy storage density and mechanical energy harvesting performance of ZnO-PVDF composites after the addition of MWCNTs was confirmed from the respective characterization studies. The sensing capability was demonstrated by the generation of similar to 22 V ac output voltage through the application of human finger tapping on 15 wt% ZnO and a 0.1 wt% MWCNT-loaded PVDF (15PZNT) based composite film. The rectified voltage from the fabricated 15PZNT film was used to charge a 10-mu F capacitor up to similar to 3 V which was used for the illumination of 30 commercial LEDs. The maximum power density from the film was found to be 21.41 mu W cm(-2) at 4 M omega load resistance. The effect of the addition of MWCNTs was also verified by simulation using COMSOL Multiphysics software
WEDM process optimization of sintered structural ceramic sample by using fuzzy-MPCI technique
No full textSintered boron carbide is an extremely hard, structural ceramic material and it is difficult to be machined with conventional techniques. To overcome the machining problem, the spark plasma sintered (SPS) monolithic boron carbide (B4C) was successfully machined by wire electrical discharge machining (WEDM) as the material is electrically conductive. The effects of five different machining parameters of WEDM were carefully observed to check their effect on the useful responses, namely machining speed and surface roughness (R-a) for cutting sintered B4C samples. A number of experimental operations were derived by using the concept of central composite design (CCD) and fuzzy logic was implemented to predict the response for a particular input parameter set. Also, a multi objective optimization was performed by fuzzy logic rule based multi performance characteristics indices technique (MPCI). (C) 2020 Elsevier Ltd. All rights reserved