IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Development of a Cu(I) doped boehmite based multifunctional sensor for detection and removal of Cr(VI) from wastewater and conversion of Cr(VI) into an energy harvesting source
No full textThis article reports a copper doped boehmite (CBH) based nano-material which is capable of detecting and removing hexavalent chromium simultaneously. Basic characterization has been performed to determine its phase purity, particle size (similar to 20 nm), morphology and surface properties (surface area 15.29 m(2) g(-1) and pore diameter 3.9 nm) by using some basic characterization tools. The Rietveld refinement method has been adopted to analyze the microstructural details of the synthesized nanostructure. Photoinduced electron transfer (PET) based quenching of fluorescence is mainly responsible for chromium sensing in this case. This nanosensor is exceptionally sensitive (limit of detection similar to 6.24 mu M) and merely selective towards hexavalent chromium ions. Industrial wastewater samples have also been used here to demonstrate the real life applicability of this material, which shows the same trend. This fluoro-sensor gains its multi-functionality when it comes to the adsorption based removal of Cr(VI) from wastewater. The synthesized material shows a remarkably high adsorption rate (similar to 85% in just 5 minutes) due to its sponge-like porous structure. Adsorption of hexavalent chromium from wastewater enhances the dielectric constant of this material significantly (similar to 7.93 times). Ionic polarization-dependent enhancement of the dielectric constant resulting from industrial wastewater treatment is a quite unmarked approach. Very low tangent loss with augmented dielectric permittivity makes this nano-material desirable for energy harvesting applications. Previously many articles have reported the sensing and removal of various industrial effluents. Keeping this in mind, this work has been designed and, apart from sensing and removal, it provides a new insight into energy harvesting from wastewater
Temperature-dependent Thermal Conductivity of a Single Germanium Nanowire Measured by Optothermal Raman Spectroscopy
No full textWe investigate temperature-dependent thermal conductivity kappa (T) in a single Ge nanowire (NW) using optothermal Raman spectroscopy, which utilizes the temperature dependence of Raman lines as a local probe for temperature. The experiment is carried out from 300 K to above 700 K, a temperature range in which thermal conductivity of single NWs has been rarely explored. The thermal conductivity of Ge NWs (grown by vapor-liquid-solid mechanism) at around room temperature is observed to lie in the range 1.8-4.2 W/m K for diameters between 50 and 110 nm. The thermal conductivity at a given temperature is found to follow a linear dependence on NW diameter, suggesting that the low magnitude of kappa (T) is determined by diffused scattering of phonons from the surface of NWs that reduces it severely from its bulk value. kappa (T) shows approximately 1/T behavior which arises from the Umklapp processes. The quantitative estimation of errors arising from the optothermal measurement and methods to mitigate them is discussed. We also suggest a quick way to estimate approximately the thermal conductivity of Ge and Si NWs using the above observations
Bio-tribological response of duplex surface engineered SS316L for hip-implant application
No full textHere we report on intelligently planned duplex surface engineering concept that utilizes a combination of plasma nitriding and multi-layering for optimizing cyclic fatigue resistance. This new concept of duplex surface engineering treatment is utilized to achieve improvement in cyclic fatigue as well as bio-tribological response of SS316L (SS) based hip-implants. The samples are SS316L (SS), Ti/TiN multi-layer-coated SS i.e., SSML and Ti/TiN multi-layer-coated plasma nitrided SS i.e., SSPNML. The samples are characterized by XRD, FESEM, TEM, nanoindentation, micro-scratch and sliding wear. In addition, cyclic fatigue behaviour up to 1 million cycles of SS and SSPNML femur heads against UHMWPE acetabular cups are studied using a hip simulator. The results prove that under comparable conditions, the nanohardness, micro-scratch resistance and sliding wear resistance of the SSPNML samples in SBF are much better than those of the corresponding SSML and SS samples. Further, as compared to the SS femoral head, the SSPNML femoral head is found to be much more resistant to cyclic fatigue. These results establish beyond doubt the superiority of the duplex surface engineering treatment utilized in the present work to achieve superb cyclic fatigue resistance in SS based femoral heads for bio-prosthetic hip implants
Cu(II) and Gd(III) doped boehmite nanostructures: a comparative study of electrical property and thermal stability
Get PDFThe present article reports the effect of transition (Cu2+) and rare earth metal (Gd3+) ion doping on structural, microstructural and electrical properties of boehmite nanoparticles. Rietveld refinement is adopted here to refine the x-ray diffractograms for further analyzing the microstructural details and their alteration due to the incorporation of foreign cations. This is probably the first time when dielectric properties of these doped boehmite samples having been reported herein. These samples show remarkably high dielectric constant values which corroborate that doping enhances the microstrain values inside the orthorhombic structure and results in higher crystallographic defects. Enhancement in defect sites causes the augmentation of relative permittivity and ac conductivity. Temperature stability has also been enhanced significantly in our Cu-doped sample. The present study enables us to determine a relationship between crystalline deformation and electrical properties of nanomaterials which may be highly beneficial in fabricating cost-effective energy harvesting devices
Probing the Influence of gamma-Sterilization on the Oxidation, Crystallization, Sliding Wear Resistance, and Cytocompatibility of Chemically Modified Graphene-Oxide-Reinforced HDPE/UHMWPE Nanocomposites and Wear Debris
No full textOsteolysis and aseptic loosening due to wear at the articulating interfaces of prosthetic joints are considered to be the key concerns for implant failure in load-bearing orthopedic applications. In an effort to reduce the wear and processing difficulties of ultrahigh-molecular-weight polyethylene (UHMWPE), our research group recently developed high-density polyethylene (HDPE)/UHMWPE nanocomposites with chemically modified graphene oxide (mGO). Considering the importance of sterilization, this work explores the influence of gamma-ray dosage of 25 kGy on the clinically relevant performance-limiting properties of these newly developed hybrid nanocomposites in vitro. Importantly, this work also probes into the cytotoxic effects of the wear debris of different compositions and sizes on MC3T3 murine osteoblasts and human mesenchymal stem cells (hMSCs). In particular, gamma-ray-sterilized 1 wt % mGO-reinforced HDPE/UHMWPE nanocomposites exhibit an improvement in the oxidation index (16%), free energy of immersion (-12.1 mN/m), surface polarity (5.0%), and hardness (42%). Consequently, such enhancements result in better tribological properties, especially coefficient of friction (+13%) and wear resistance, when compared with UHMWPE. A spectrum of analyses using transmission electron microscopy (TEM) and in vitro cytocompatibility assessment demonstrate that phagocytosable (0.5-4.5 mu m) sterilized 1 mGO wear particles, when present in culture media at 5 mg/mL concentration, induce neither significant reduction in MC3T3 murine osteoblast and hMSC growth nor cell morphology phenotype, during 24, 48, and 72 h of incubation. Taken together, this study suggests that gamma-ray-sterilized HDPE/UHMWPE/mGO nanocomposites can be utilized as promising articulating surfaces for total joint replacements
Conducting polyaniline decorated in-situ poled Ferrite nanorod-PVDF based nanocomposite as piezoelectric energy harvester
No full textPVDF-metal oxide based piezo-nanocomposite is an promising substitute of flexible nanogenerator. Herein, a ternary nanocomposite system Zinc Ferrite nanorod/Polyvinylidenefluoride (PVDF)/Polyaniline (PANI) nanochains was presented as alternative energy harvesting material. The inherent problem of low short-circuit current and high internal resistance of the nanocomposite was minimised by introducing a third phase cost-effective conducting supplementary filler, PANI nanochain.PANI assist to overcome the local dielectric dissimilarity by easy formation of conduction pathways via delocalization of pi-electrons present in the benzene ring and reduce the internal resistance of composite. Besides, it serves the role of dispersing agent by floating nanofillers throughout the volume and improves the homogeneity of filler distribution. Additionally, PANI reinforces composite with respect to stress accumulation and modulates the release behaviour by entangling with nanofillers by means of Van Der Waals force and helps to stabilize the polar PVDF. This lead to an improvement in electro-mechanical response and piezo-response behaviour of nanocomposite. The nanocomposite exhibits a similar to 42 V ac open circuit voltage and short circuit current density similar to 0.85 mu A/cm(2) with an overall increase in power density 35% compare to its binary metal-oxide/PVDF nanocomposite counterpart in response to single finger tapping and releasing. The generated power was utilized to illuminate twenty six number of red LEDs without any external energy storage unit. Also, the nanocomposite could charge up a commercial capacitor (10 mu F) within 115 s which can be used for alternative powersource in self-powered devices and sensors. (C) 2019 Published by Elsevier B.V
Microwave-assisted alumina-zirconia brazed joint for microwave tubes
No full textAlumina-zirconia joint was fabricated by microwave-assisted brazing technique at 980 degrees C for 15 min using TICUSIL (68.8Ag26.7Cu4.5Ti in wt%) as the brazing alloy. The brazed joints were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Vickers microhardness evaluation, brazing strength measurement, and helium leak test. X-ray diffraction analysis confirmed the formation of Ti-based compounds at the substrate-filler alloy interfaces of the brazed joints. SEM images showed the substrate-filler alloy interfaces of the brazed joints. The EDX analysis determined the elemental compositions along the joint cross-section. Vickers microhardness measurement indicated reliable joint performance for the microwave-assisted brazed joints during actual application. Brazing strength measurement and helium leak test proved the formation of sound alumina-zirconia brazed joint by both microwave and conventional heating techniques. Scratch tests were performed on the cross-sectional surfaces of the alumina-zirconia joints. Scratch test results established the strong interfacial strength of the microwave brazed joints
Synthesis, characterization and in vitro biocompatibility study of strontium titanate ceramic: A potential biomaterial
Get PDFStrontium (Sr), a mineral element present in trace in the human body, has significant effect on bone remodelling. Sr containing ceramics have huge potential to heal bone defects and improve osseointegration of implants. In this study, perovskite oxide – strontium titanate (SrTiO3) was synthesized and explored its potential for biomedical applications. The phase pure SrTiO3 powder was synthesized from solid state reaction of strontium carbonate (SrCO3) and titanium dioxide (TiO2) at 1200 °C for 2 h. The as synthesized SrTiO3 powder, pure hydroxyapatite (HAp) and SrTiO3-50 wt% HAp (SH50) premixed powders were sintered at different temperatures varies from 1100 to 1400 °C in air. The sintered samples were characterized using X-ray diffraction (XRD) for phases and scanning electron microscopy (SEM) for microstructure analysis. XRD results revealed no dissociation of HAp or reaction with SrTiO3 during sintering. The sintered samples were studied for mechanical properties, wettability, and biocompatibility. The relative density of the sintered SrTiO3 increases with increasing sintering temperature. The relative density of SrTiO3 was increased from 77% to 98% with increase in sintering temperature from 1250 to 1400 °C. The substantial improvement of hardness and compressive strength was observed for sintered SrTiO3 compared to HAp of similar porosity level. The hardness and compressive strength of SrTiO3 sintered at 1250 °C found ~6 and ~3.5 times higher than sintered HAp. In vitro dissolution study carried out in phosphate buffer solution at 37 °C, confirmed the release of Sr2+ ion from the bulk SrTiO3 sintered at 1250 °C. The in vitro cell materials interaction showed cytocompatibility of sintered SrTiO3 and SrTiO3-HAp composite. In summary, excellent biocompatibility of SrTiO3 with superior mechanical properties confirmed its potential as novel biomaterial for use in the repair of infected or aseptic bone defects
Microstructural evolution and its outcome on the photo induced micro actuation effect and mechanical properties of copper doped Co-Ni-Al FSMA
No full textIn this work, we studied the effect of doping with copper to seek improvement in mechanical and photo induced micro actuation (PIMA) properties of a Co-Ni-Al ferromagnetic shape memory alloy (FSMA). Unique and unexplored PIMA property of FSMA system has opened up the scope of various laser controlled micro-mechanical engineering applications in miniature scale. Transmission Electron Microscopy and X-ray diffraction technique were used to characterize and correlate the evolved microstructure with the corresponding changes in the PIMA and mechanical properties. Magnetic properties of these samples were studied by performing hysteresis experiments at room temperature. It was found that partial substitution of cobalt with copper resulted in samples with lower magnetic and PIMA properties but better mechanical property, however, in case of substituting aluminum, it resulted in improvement of the ferromagnetic property but destroyed the PIMA effect altogether. In order to understand these properties changes, the electron density of each of the samples was calculated and compared. These studies should help in deciding on use of new alloys with optimization of PIMA and mechanical property for desired and customized engineering applications. (C) 2020 Elsevier B.V. All rights reserved