IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Evaluation of functionality in Ni@stabilized ZrO2 and NiO@NiO-Zn through X-ray diffraction technique
No full textA mathematical model is developed for calculating X-ray penetration depth based on the theories of diffraction to quantitatively characterize the heterogeneous functional materials with core-shell morphology. Functional materials viz. Ni@stabilized ZrO2 (SZ) and NiO@NiO-Zn are synthesized and penetration depth (xi Ni/xi NiO) is calculated. Ni@SZ and NiO@NiO-Zn function as effective catalyst for methane steam reformation and olefin epoxidation respectively. Functionality of the catalysts lies in the core-shell morphology with interconnection among the phases. The author's aim to optimize the shell thickness using the mathematical model and correlate with the catalyst activity. Sequential increase of Ni-content in Ni@SZ from 25 to 40 vol % results in reduction of penetration depth similar to 2.1 to 0.8 mu m] relative to core (xi(S)(Z-core)) thereby restricting the SZ contribution and limiting the oxide ion percolation. Similarly, surface coverage of nano NiO onto NiO-Zn for olefine epoxidation requires the involvement of three zone region viz. NiO, Zn and pi electron cloud of the substrate. Effectivity of the catalytic activity of such NiO@NiO-Zn matrix is found optimum (4.3 mu m w.r.t.xi(NiO)) with the penetration depth derived from mathematical modeling. Hence, such modeling reveals its significance towards finding the penetration depth for core-shell type functional materials for catalysis compared to disperse heterogeneous catalyst
Ceramic membrane-based ultrafiltration combined with adsorption by waste derived biochar for textile effluent treatment and management of spent biochar
No full textPurpose Effluents produced in the textile industries are important sources of water pollution due to the presence of toxic dyes, auxiliary chemicals, organic substances etc. Recycling of such industrial wastewater is one major aspect of sustainable water management; hence present study is focused on an eco-friendly process development for reclamation of higher loading textile wastewater. Method Industrial effluent samples with varying loading were collected from textile processing units located in and around Kolkata city. Vegetable waste collected from local market was utilized to prepare an efficient biochar for elimination of the recalcitrant dyes. Prior to adsorption, ceramic ultrafiltration (UF) process was used for reduction of the organic loading and other suspended and dissolved components. Results A remarkably high BET surface area of 1216 m(2)g(-1)and enhanced pore volume of 1.139 cm(3)g(-1)was observed for biochar. The maximum adsorption capacity obtained from the Langmuir isotherm was about 300 mg.g(-1). The combined process facilitated >99% removal of dyes and 77-80% removal of chemical oxygen demand (COD) from the various samples of effluent. The treated effluent was found suitable to discharge or reuse in other purposes. About 95% of dye recovery was achieved during biochar regeneration with acetone solution. The dye loaded spent biochar was composted with dry leaves and garden soil as bulking agent. Prepared compost could achieve the recommended parameters with high nutritional value after 45 days. Conclusions The overall study showed potential of the proposed process towards treatment of toxic dye loaded textile effluent in an environment friendly and sustainable approach
Paths to lowering critical point in a two-dimensional order-disorder transition by Au nanoparticle `decoration'
No full textEffect of mixing dodecanethiol-capped Au nanoparticles (AuNPs) on the critical point of the liquid ordered (Lo) to liquid disordered (Ld) phase transition of myristic acid (MyA) Langmuir monolayer has been studied through quantitative evaluation of the two-dimensional patterns of AuNP clusters created through de-mixing and observed through Brewster angle microscopy. The critical temperature (Tc), marked by the emergence of a Bethe lattice-like (BLL) pattern of `fingers' and `arms', was brought down from 38 degrees C in pristine MyA monolayers to 28 and 10 degrees C for 20 and 40% w/w AuNP concentrations. Analysis of the BLL at the length scales of these `fingers' and `arms' showed that the lowering of Tc follows two different paths for the two concentrations, through a repulsive force for the lower and an attractive force for the higher concentration at the `fingers' length scale, while at the scale of `arms' the force between NPs is always repulsive. Based on the observations that the repulsive force operates at larger interparticle separation and the attractive one acts at smaller separations, we tentatively assign the first to be a dipolar repulsion and the second to be lipophilic force of quantum mechanical origin. We have also indicated qualitatively how this realignment of forces between nanoparticles can affect the lipophilic force between the hydrocarbon chains of the NP capping and those chains in the monolayer
Bio-synthesis of SnO2 and comparison its CO sensing performance with conventional processes
No full textThe present paper reports on a unique eco-friendly bio-synthesis process of tin oxide using water extract of soaked kabuli chickpea seeds as natural binder. The structural, microstructural and CO sensing properties of the newly synthesized tin oxide were compared with those of conventional sol-gel and sonochemical processes. XRD results of the bio-synthesized material revealed the formation of single tetragonal phase of SnO2 similar to sol-gel and sonochemical processes. The bio approach led to the formation of finer nanoparticales with a higher specific surface area similar to 60 m(2)/gm compared to the others. The average sizes of tin oxide nanoparticles as observed from TEM images were about 35 nm, 15 and 6 nm for the sonochemical, sol-gel and biosynthesis respectively. These tin oxide powders were used to fabricate Taguchi based sensors and their CO sensing performance were evaluated. The biosynthesized tin oxide sensor showed similar to 53% sensing performance for 30 ppm CO which was better than sol-gel (similar to 44%) or sonochemical (similar to 42%) tin oxides operating at similar condition. The reported results suggest that the biosynthesis is a promising cost effective method to prepare nanocrystalline SnO2 for sensing application. (C) 2019 Elsevier B.V. All rights reserved
Prospects of photonic crystal fiber for analyte sensing applications: an overview
No full textThe detection and monitoring of physical, chemical and biomedical parameters are increasingly reliant on fiber-optic sensing technology. Of applicable optical methods, photonic crystal fiber (PCF) sensors show its potential as a sensitive technique in environmental, industrial, food preservation and medical applications. Such a system incorporates the fabrication of a particular PCF, the interaction of wave propagation with the measured field, signal processing to offer automated real-time measurement in terms of the amplitude, phase, polarization and wavelength of spectrum. This article is an endeavour towards giving a brief overview of the development of analyte sensors using PCFs in the last few years. Different kinds of PCF analyte sensors are discussed based on the measuring entity and reported works. This discussion integrates a variety in the nature of the core, metal coating on the PCF and liquid infiltration in the holes. It is also considered to present the phenomena of its internal structure and interference techniques for several applications. Advances in this technology, particularly in the areas of gas sensing, chemical spices and bio analytes, will be discussed in this article with some applications
Effect of surface pinning on magnetic nanostuctures
No full textWe show that pinning of surface spins affects the hysteresis properties of the core-shell magnetic nanostuctures of different shapes, sizes, and different spin interactions, namely, Ising, XY, and Heisenberg models. The asymmetry in hysteresis loops occuring due to pinning turns out to be more prominent in an inverse core-shell structure where spin interaction in the core is antiferromagnetic and that in the shell is ferromagnetic. Monte Carlo simulations of the inverse core-shell nanostructures show that the exchange bias, even under zero-field-cooled conditions, increases with increase of both the pinning density and the fraction of up spins among the pinned ones. The exchange bias also exhibits a switch-from negative to positive-depending on the fraction of up spins pinned. These results are remarkably well reproduced by a simple model of the outermost surface layer. The surface spin pinning appears to affect the magnetic properties of heterostructures as well, besides nanostructures
An in vitro comparative study of layered-double hydroxide nanoconjugate in the delivery of small interference and short-hairpin ribonucleic acid
Get PDFAlzheimer's disease is a disease which cannot be cured completely. In this aspect ribonucleic acid interference (RNAi) therapy is a prospective therapeutic mechanism which can be used for identifying a future curative procedure. RNAi therapy comprises small interfering RNA (siRNA), short hairpin (shRNA) and micro-RNA therapeutics. Within these three mechanisms we have identified two of them as an effective method of combating this genetic incurable disease. siRNAs and shRNAs are very much effective in vitro that is already proved in many research work. In our study we have used a very potent, biocompatible nanoparticle-layered double hydroxide for delivering these macromolecules. However, the intercalation and cellular internalization of these macromolecules demonstrated significant differences. As siRNAs have low-molecular weight than shRNAs they demonstrated different characteristics in the case of internalization within layered-double hydroxide and while cellular internalization. At the end of this study it has been found that both of these macromolecules may be used as a therapeutic approach of Alzheimer's disease after studying it in future in animal and human subjects
Investigating the role of amides on the textural and optical properties of mesoporous-nanostructured theta-Al2O3
Get PDFMesoporous-nanostructured theta-Al2O3 was synthesized by an autoclaving technique using different amides i.e., formamide (F), dimethyl formamide (DMF) and diethyl formamide (DEF) at 150 degrees C/24 h followed by calcination at 1000 degrees C. Crystallization and structural behaviour of the as-synthesized materials were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The porosity study was carried out by N-2 adsorption-desorption (BET) technique. Microstructural features were measured by transmission electron microscopy (TEM). The amide-based solvents played a deliberate role in microstructural and textural features of theta-Al2O3. The DMF-based solvent showed an enhanced surface area of 158 m(2) g(-1). The as-prepared theta-Al2O3 rendered a nano-sheet, nano-rod and nano-flake like morphology for F, DMF and DEF derived products, respectively. From the UV-Vis spectroscopic measurement, the estimated band-gap of theta-Al2O3 was found to be 5.16-5.40eV. Photoluminescence investigation further revealed blue emission particularly for excitation at a wavelength of 252 nm. A DMF-derived sample rendered the lowest band gap due to its smaller crystallite size and higher surface area compared to that of F- and DEF-derived samples
Current Developments in 3D Bioprinting for Tissue and Organ Regeneration–A Review
Get PDFThefield of Tissue engineering and regenerative medicine that work toward creatingfunctional tissue-constructs mimicking native tissue for repair and/or replacement ofdamaged tissues or whole organs have evolved rapidly over the past few decades.However, traditional tissue engineering approaches comprising of scaffolds, growthfactors and cells showed limited success in fabrication of complex 3D shapes andinvivoorgan regeneration leading to their non-feasibility for clinical applications from alogistical and economical viewpoint. In this regard, 3D bioprinting, which is an extendedapplication of additive manufacturing is now being explored for tissue engineering andregenerative medicine as it involves the top-down approach of building the complex tissuein a layer by layer fashion, thereby producing precise geometries due to controlled nature ofmatter deposition with the help of anatomically accurate 3D models of the tissue generatedby computer graphics. Here, we aim to provide a comprehensive review of the 3Dbioprinting technology along with associated 3D bioprinting strategies including ink-jetprinting, extrusion printing, stereolithography and laser assisted bioprinting techniques.We then focus on the applications of 3D bioprinting technology on construction of variousrepresentative tissue and organs, including skin, cardiac, bone and cartilage etc. Wefurther attempt to highlight the steps involved in each of those tissues/organs printing anddiscuss on the associated technological requirements based on the available reports fromrecent literature. Wefinally conclude with current challenges with 3D bioprintingtechnology along with potential solution for future technological advancement ofefficient and cost-effective 3D bioprinting methods
Nano-ZnO decorated ZnSnO3 as efficient fillers in PVDF matrixes: toward simultaneous enhancement of energy storage density and efficiency and improved energy harvesting activity
No full textHere, we report the effect of ZnO decoration on ZnSnO3 fillers on the dielectric property, energy storage behaviour and mechanical energy harvesting performance of PVDF matrixes. More enhanced dielectric constant and reduction in dielectric loss were achieved in PVDF-ZnO@ZnSnO3 (PVDF-ZNZS) films than in PVDF-ZnSnO3 (PVDF-ZS) films for the same concentration of filler loading. Similarly, PVDF-ZNZS films showed simultaneous enhancement in electrical energy storage density and storage efficiency compared to PVDF-ZS composites. As all the constituent materials (PVDF, ZnSnO3 and ZnO) were piezoelectric, the resulting composite film showed improved piezoelectric energy harvesting performance too. After rectification, the output ac voltage was used to charge a 10 mu F capacitor up to similar to 5 V dc which was further used to light up some LEDs. Furthermore, in order to exhibit improved sensitive output, a hybrid piezo-tribo nanogenerator was fabricated which was demonstrated as a motion sensor, a weight sensor and a human body movement sensor as part of a real life application