Table of Contents - Volume 15 Number 2

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Harvesting energy from environment presents a remarkable practical way to supply energy for smart self-powered advanced devices such as remote sensing devices, wireless networks, biomedical and wearable devices. A nanogenerator converting mechanical/thermal energy into electricity is an interesting emerging technology since it produces energy from environment. The nanogenerators have different energy production approaches about which many significant studies are going on. In recent years, technological and scientific researches have been focused on flexible devices to increase the application fields. Besides, increasing work on nanogenerators showed that providing flexibility to these devices will contribute to producing more ergonomic smart systems. The devices, which are capable to be used in textile, medical, mechanical etc. industries are also designed especially in academic studies. In this review, recent trends in the field of flexible nanogenerators were presented by demonstrating new potential applications in different areas. 

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Thin film of Lead oxide (PbO) was prepared by spray pyrolysis technique on glass substrate at 250^°C. The cyclic voltammetry measurement was carried out to study the oxidation reduction reactions of non-aqueous lead ions at various molar concentrations which is from 0.01M to 0.09M. Elecrochemical studies were carried out  with Ag/AgCl as a reference electrode , Pt as working electrode while platinum mesh as counter electrode.Lead oxide appears to be poisonous yellow or reddish yellow solid. Structural characterization of films was analyze with X- ray diffraction (XRD) and optical band gap was determined by UV-Vis Spectroscopy.

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The problem with waste waters containing dyes is that these impurities impart acute and/or chronic consequences once exposed to living organism. The results of this exposure depend upon dye concentration, exposure time, besides their ability to absorb/reflect sunlight entering in to the aqueous media.  Thus the concentration of these organic dyes leads to severe effects on the growth of aquatic life as well as other living organism that found entrance. Unlike the existing reports which present chemical decomposition by oxidation, photodegradation, microbial decoloration, use of activated sludge, etc., here in this work we have purely highlighted the cost-effective and easy to handle approach (adsorption) for the removal of dyes from the waster waters. Conclusions have been drawn from the compiled literature and few crucial regarding futuristic research for the removal of dyes have been presented.

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Magnetic Iron Oxide Quantum Dots (MIOQDs) were synthesized using Moringa oleifera leaves through green technique i.e., Microwave treatment. The synthetic method is highly rapid, simple and economical. MIOQDs were formed by reduction of ferric chloride (FeCl₃) solution with Moringa oleifera leaf extract without any influence of alkaline conditions which opens a new arena for the phytosynthesis of nanoparticles. MIOQDs structural characteristics were scrutinized by Powder X-ray diffraction method, FESEM, TEM, UV –Visible Spectroscopy, Photoluminescence Emission Spectroscopy. The  ultraviolet-visible spectrum  recorded for the aqueous  media iron  nanoparticles  showed  an  absorption peak  at  around  330 nm. Powder X-ray diffraction showed that the particles are crystalline in nature, with both hematite and maghemite structure.

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Single crystals of Sulphamic Acid doped with Zinc Sulphate and Manganese Sulphate were grown at room temperature using slow evaporation technique. Structural analysis of the grown crystals was done using single crystal X Ray Diffraction and powder X Ray Diffraction studies. Various functional groups seen in the grown crystals are determined using FTIR spectroscopic analysis. The cut-off wavelength of ZnSO₄ and MnSO₄ doped Sulphamic acid were evaluated by UV-Vis-NIR spectral studies. Thermal behaviour of the grown crystals was identified from Thermogravimetric Analysis (TGA) and Differential Thermogravimetric Analysis (DTA). The mechanical strength and Second harmonic generation of the grown crystals was identified by Vicker’s Microhardness Test and Kurtz powder technique respectively.

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Due to their cost effectiveness, greater strength and ease of fabrication, polymer composites are noticeable candidate almost in all areas. However, when they are used in their original form they possess very low wear resistance and hardness. The present investigation gives information on mechanical properties of polymer matrix composites where LDPE (Low density polyethylene) is used as polymer matrix and TiO₂, Al₂O₃ and CaCO₃ are used as reinforcements. The samples were prepared according to ASTM standards by injection moulding machine with varying percentage of reinforcements in polymer matrix. Tests viz., tensile, flexural impact are carried out.

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Diglycidyl ether of bisphenol A based epoxy resin was loaded with alkyl quaternary ammonium modified bentonite clay nanoparticles (b-CNPs) in various concentrations. The abrasion resistance (Taber) property of the composite coatings cured with amine were investigated after 7 days and with 60 days curing at two different cycle viz. 500 and 1000. The mass losses of the materials revealed the fact that abrasion resistance increases with increase in CNPs concentration inside epoxy matrix with ageing. Thermal (DSC), spectroscopic (FTIR) and morphological (SEM) studies were performed to characterize the developed epoxy nanocomposite (ENC) coating. A gradual decrease in glass transition temperature (Tg) was observed with increase in the b-CNPs concentration. The modified b-CNPs found interacting with epoxy matrix and the intensity found increasing with increase in b-CNPs concentration during spectroscopic study. Smooth film morphology was revealed by scanning electron microscopic analysis confirming the uniform dispersion of b-CNPs inside polymer nanocomposite matrix.

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The emerging concept of thread-based microfluidics has shown great promise for application to inexpensive disease detection and environmental monitoring. This paper describe the properties of thread for the development of thread based low-cost microfluidics device for the diagnostic, food safety and environmental assay. Various properties of thread like capillary flow, wicking capacity and absorption capacity, make them important to fabricate the low-cost microfluidics device. In this paper, three different thread sample viz. cotton yarn, cotton thread and spun thread were taken and different properties like wicking capacity, fluid capillary flow, absorption capacity were measured as well as Scanning Electron Microscopic (SEM) analysis of the same was also carried out to study the morphology and texture of thread fibers. Data obtained from result indicate that the cotton thread having all the ideal characteristic to fabricate the diagnostic device and thus it is suitable for the fabrication of thread based microfluidics device for the diagnostic purpose.

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The study of alkaline earth doped stannate ceramics of Barium and Calcium is being carried out to explore more on the phosphorescent applications. The present study is an energy and cost-efficient green approach towards the preparation of Europium (III) doped stannate of Calcium and Barium in the nano scale as it involves the biowaste of egg shell as a precursor for calcium carbonate and the plant extract of aloe vera as the reaction medium and a comparatively lower calcination temperature than reported so far. The structure, phase purity, surface morphology and applications in terms of photo luminescence, photo catalytic and anti-microbial activities have been investigated. The doping of alkaline earth metal of Europium in lower weight percentage (lesser than one) was carried out at lower processing temperatures than reported earlier. There was a phase transition in the case of barium stannate upon doping and there were observable changes in crystallite size, morphology and microstructure in the case of Stannates of Calcium and Barium. The results of photo luminescence study and the photo catalytic degradation of methylene blue dye were encouraging. The anti-microbial study in terms of toxicity of the doped samples in smaller dosages upon Pseudomonas aeruginosa, Staphylococcus aureus provided a new dimension to their application.

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