Hydrothermal synthesis of zirconium oxide nanoparticles and its characterization

The paper presents the preparation and investigations of zirconium oxide (ZrO₂) nanoparticles that were synthesized by hydrothermal method. The products were characterized by means of powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-absorption spectroscopy and photoluminescence (PL) spectroscopy. The crystal structure was determined using X-ray diffraction. The morphology and the particle size were studied using (SEM) and (TEM). The spherical shaped particles were confirmed through the SEM analysis. The transmission electron microscopic analysis confirmed the formation of the nanoparticles with the particle size. The FT-IR and Raman spectrum ascertained the strong presence of ZrO₂ nanoparticles. The optical properties were obtained from UV–visible absorption spectrum and also PL emission spectrum. The dielectric constant and the dielectric loss were measured as a function of frequency and temperature.     

Rare earth (RE) doped phosphors and their emerging applications: A review

The evolution of luminescent materials has witnessed rapid advancement in research and development. Solid inorganic light-emitting materials or phosphors are the optoelectronic material of the 21st century because of their power-efficient potential over various illumination sources, eco-friendliness and resourceful display perspectives. The inorganic phosphors have been extensively explored to meet the demand of low voltage stimulated lighting sources owing to increased global energy consumption. Due to environmental friendliness, advantages long lifetime, lower energy consumption, reliability and high luminous efficiency, modern white light-emitting diodes (WLEDs) have replaced less effective incandescent and mercury-enclosing conventional fluorescent lighting sources. This review highlights the developments in preparation, luminescence and potential perceptions of rare-earth activated phosphors for solid-state lighting technologies. The role of RE ions as an activator as well as a sensitizer in doped materials and possible transitions within their energy levels are reviewed in detail. The paper reviews the substantial influence of host lattices such as aluminate, oxide, phosphate, silicate, sulfide, etc on the optical transitions of doped RE ions. Studies on the advancement into the design of novel phosphors are very crucial as they will provide an opportunity to boom prospects in the course of promising applications. The sustainable energy facilities include clean technologies providing a cheaper lighting source which can produce significant indirect economic benefits via limiting the deforestation and use of scrubbing technology to mitigate air pollution.     

Tailoring of optical and electrical properties of PMMA by incorporation of Ag nanoparticles

Silver–poly(methyl methacrylate) (Ag–PMMA) nanocomposite films were prepared via ex situ chemical route by employing sodium borohydride (\(\hbox {NaBH}_{4}\)) as a reducing agent. In this study, PVP-stabilized Ag nanoparticles were prepared and mixed with PMMA solution. Optical and structural characterizations of resulting nanocomposite films were performed using UV–visible spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Characteristic surface plasmon resonance (SPR) peak of Ag nanoparticles was observed at about 3.04 eV (408 nm) in absorption spectra of Ag–PMMA nanocomposite films. TEM micrograph revealed that the spherical Ag nanoparticles with an average diameter of 5.4\(\,\pm \,\)2.5 nm are embedded in PMMA. In Raman spectra, besides shifting of vibrational bands, enhancement in intensity of Raman signal with incorporation of Ag nanoparticles was observed. Current (I)–voltage (V) measurements revealed that conductivity of PMMA increased with increasing concentration of Ag nanoparticles. Analysis of I–V data further disclosed that at voltage <2 V, ohmic conduction mechanism is the dominant mechanism, while at voltage >2 V Poole–Frenkel is the dominant conduction mechanism. Urbach’s energy, the measure of disorder, increased from 0.40 eV for PMMA to 1.11 eV for Ag–PMMA nanocomposite films containing 0.039 wt% of Ag nanoparticles.     

Optical and electrical smart response of chemically stabilized graphene oxide

Graphene oxide (GO) was prepared using a modified Hammer’s technique and by utilizing a sonochemical approach. The paper deals with the synthesis and the characterization of GO besides the structural, morphological, optical and electrical properties of GO. Phase formation of the prepared sample was examined with powder X-ray diffraction (XRD), the typical surface morphology was carried out by utilizing Scanning electron microscopy (SEM) and the high resolution Transmission Electron Microscopy (HR-TEM). The different functional groups were recognized by utilizing FT-IR and Raman spectroscopy. The optical properties were studied utilizing optical absorption and photoluminescence (PL) spectra. At various frequencies and temperatures the dielectric properties of the GO, such as the dielectric constant, the dielectric loss, and AC conductivity were studied. Further, the electrical behaviour of GO was analysed using I-V and C-V characteristics. These novel findings shed focus on high yield electronic material GO, which can only be realized as the field moves forward and makes more significant advances in smart opto-electronic devices.     

A deep learning based approach to detect IDC in histopathology images

Multimedia Tools and Applications - Breast cancer is one of the widespread reasons of morbidity worldwide that begins in the cells of the tissues of morbidity worldwide in the woman community....     

Amount of training and cue-evoked taste-reactivity responding in reinforcer devaluation.

In two experiments, rats received minimal (16) pairings of one auditory conditioned stimulus (CS) cue with a sucrose reinforcer, and extensive (112) pairings of another auditory CS with that reinforcer. After sucrose was devalued by pairing it with lithium chloride in some rats (Devalue groups) but not others (Maintain groups), taste reactivity (TR) and other responses to unflavored water were assessed in the presence of the auditory CSs alone. The minimally trained CS controlled substantially more evaluative TR responses than the extensively trained CS. Those TR responses were hedonic (positive) in the Maintain groups, but aversive (negative) in the Devalue groups. By contrast, food cup entry and other responses thought not to reflect evaluative taste processing were controlled more by the extensively trained cue. These responses were reduced by sucrose devaluation comparably, regardless of the amount of training. The results suggest rapid changes in the content of learning as conditioning proceeds. Early in training, CSs may be capable of activating preevaluative processing of an absent food reinforcer that includes information about its palatability, but that capability is lost as training proceeds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fabrication of comb structure with vertical sidewalls in Si (110) substrate by wet etching in boiling KOH solution

Microsystem Technologies - This paper discusses about the fabrication of comb-structure with vertical sidewall profile by wet chemical etching of Si (110) substrate in boiling KOH solution. Etch...     

Modification of structural,thermal, and electrical properties of PVA by addition of silicon carbide nanocrystals

SiC‐PVA nanocomposite films, synthesized using solution‐casting technique were structurally characterized using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Morphological studies of the SiC‐PVA nanocomposite films were carried out using Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). TEM analysis confirms that the size of SiC nanocrystals present in PVA matrix are 23 ± 9 nm, which is consistent with size calculated using XRD. SiC‐PVA nanocomposite films were further characterized for their thermal and electrical properties. Thermogravimetric/differential thermal analysis (TG/DTA) indicates that the char yield of nanocomposite films containing 3 wt % SiC nanocrystal is ～30% more than PVA. This increase in char yield is an indication of the potency of flame retardation of SiC‐PVA nanocomposite films. I‐V analysis reveals that Schottky mechanism is the dominant conduction mechanism which is responsible for the increase in conductivity of PVA with the addition of SiC nanocrystals. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42464.     

Rapid photokilling of gram-negative Escherichia coli bacteria by platinum dispersed titania nanocomposite films

Superior antimicrobial activity of 2 wt.% Pt-dispersed TiO₂ thin film was observed in photokilling Gram-negative Escherichia coli bacteria within 5 min irradiation (640 μW cm⁻², λ > 340 nm) from UV torch than bare TiO₂ film. Severe disruption of cell membrane has occurred over illuminated Pt-TiO₂ catalysts films coated with 100–300 μg powders per 5 cm² areas over sterilized glass slides. The Pt dispersion onto TiO₂ by impregnation–hydrogen reduction always exhibited better photokilling effect than Pt photodeposition, irrespective of Pt–TiO₂ dose and light exposure time. Similar trend in photoactivity difference between two Pt–TiO₂ catalysts is also observed in aqueous slurry because of the unlike surface structure of TiO₂ due to different annealing temperatures, size and nature of Pt particles dispersion onto TiO₂ photocatalysts.     

Estimation of bending of micromachined gold cantilever due to residual stress

Electroplated gold is widely used as the material for the micromachined beam structures due to its excellent electrical and mechanical properties. This work attempts to analyze the surface micromachined gold cantilever beams under inherently present stress gradient. The structure is analyzed by using finite element method simulation at different intrinsic stress gradients. The gold layers are deposited using cyanide electroplating bath operated at different current densities. Residual stresses in electroplated gold layers deposited on photoresist coated silicon samples are estimated by using X-ray diffraction technique. Cantilever beam structures are fabricated using surface micromachining technique. The tip deflections of the fabricated cantilever beams are found to be ~16 and 8 μm corresponding to the 1.0 and 0.7 mA/cm² current densities (mean), respectively. The corresponding intrinsic stress gradients are estimated to be ?13.9 and ?7.2 MPa/μm, respectively. Simulated and measured values of residual stresses are well matched.