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Anchoring Bi4O5I2 and AgI nanoparticles over g-C3N4 nanosheets: Impressive visible-light-induced photocatalysts in elimination of hazardous contaminates by a cascade mechanism
No full textIn this research, Bi4O5I2 and AgI nanoparticles were anchored over g-C3N4 nanosheets (denoted as NGCN/Bi4O5I2/AgI) to preparation highly impressive visible-light-driven samples. The synthesized nanocomposites were investigated by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), UV-vis diffuse reflectance spectroscopy (DRS), energy dispersive analysis of X-rays (EDX), electrochemical impedance spectroscopy (EIS), photocurrent density, Brunauer-Emmett-Teller (BET), and photoluminescence (PL) analyses. Among the ternary photocatalysts, the NGCN/Bi4O5I2/AgI (20%) photocatalyst illustrated the highest photoactivity in degradation of rhodamine B (RhB), which was approximately 58.4, 15.2, and 12.8 times higher than the GCN, NGCN, and NGCN/Bi4O5I2 (20%) samples, respectively. Furthermore, the center dot O-2(-) was discovered as the main species in the respective system by the quenching tests. Also, by studying the electrochemical properties, a cascade photocatalytic mechanism was suggested based on the energy bands to describe the enhanced charge carriers migration and separation, which caused impressive photocatalytic performances in degradations of four hazardous contaminants. This study highlights the rational anchoring of Bi4O5I2 and AgI nanoparticles over NGCN to prepare highly efficient photocatalysts for wastewater remediation. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved
Tailored piezoelectric performance of self-polarized PVDF-ZnO composites by optimization of aspect ratio of ZnO nanorods
No full textAspect ratio of filler plays a crucial role to study the electrical properties of polymer based composite system. Here, we investigated the effect of filler aspect ratio on the electrical properties of zinc oxide (ZnO) incorporated poly(vinylidene fluoride) (PVDF) matrix. ZnO nanorods having different aspect ratio were synthesized by the hydrothermal technique with varying reaction time 4 to 20 hours at a fixed temperature and PVDF based nanocomposites of the respective ZnO nanorods with different wt% filler loading were fabricated. Interestingly polar-phase fraction increased with the aspect ratio of ZnO nanorods. The nanocomposites with higher aspect ratio ZnO nanorods showed an increased energy density under same electric field and exhibited maximum open circuit AC output voltage (ie, 20 V) after the application of repeated human finger tapping. This result indicates that high aspect ratio ceramic filler provides an effective approach to enhance the dielectric, ferroelectric, energy storage, and energy harvesting performances of ceramic-polymer nanocomposites
Pro-Oxidant Therapeutic Activities of Cerium Oxide Nanoparticles in Colorectal Carcinoma Cells
Get PDFGiven that basal levels of reactive oxygen species (ROS) are higher in cancer cells, there is a growing school of thought that endorses pro-oxidants as potential chemotherapeutic agents. Intriguingly, cerium oxide (CeO2) nanoparticles can manifest either anti- or pro-oxidant activity as a function of differential pH of various subcellular localizations. In an acidic pH environment, for example, in extracellular milieu of cancer cells, CeO2 would function as a pro-oxidant. Based on this concept, the present study is designed to investigate the pro-oxidant activities of CeO2 in human colorectal carcinoma cell line (HCT 116). For comparison, we have also studied the effect of ceria nanoparticles on human embryonic kidney (HEK 293) cells. Dose-dependent viability of cancerous as well as normal cells has been assessed by treating them independently with CeO2 nanoparticles of different concentrations (5-100 mu g/mL) in the culture media. The half maximal inhibitory concentration (IC50) of nanoceria for HCT 116 is found to be 50.48 mu g/mL while that for the HEK 293 cell line is 92.03 mu g/mL. To understand the intricate molecular mechanisms of CeO2-induced cellular apoptosis, a series of experiments have been conducted. The apoptosis-inducing ability of nanoceria has been investigated by Annexin V-FITC staining, caspase 3/9 analysis, cytochrome c release, intracellular ROS analysis, and mitochondrial membrane potential analysis using flow cytometry. Experimental data suggest that CeO2 treatment causes DNA fragmentation through enhanced generation of ROS, which ultimately leads to cellular apoptosis through the p53-dependent mitochondrial signaling pathway
Enhanced triple-pass hybrid erbium doped fiber amplifier using distribution pumping scheme in a dual-stage configuration
No full textAn enhanced triple-pass hybrid optical fiber amplifier in a dual-stage configuration is presented by utilizing a combination of hafnium-bismuth erbium-doped fiber (HB-EDF) and bismuth erbium-doped fiber (Bi-EDF) as gain medium. The total Erbium-doped fiber length was only 199 cm, and both HB-EDF and Bi-EDF were forward pumped by 1480 nm with an optimum pump power of 170 mW and 110 mW, respectively to provide flat gain and wideband amplification. At high input power of -10 dBm, a flat gain of about 19 dB with gain fluctuation of less than 2 dB was observed over wideband ranging from 1555-1600 nm. On the other hand, the noise figure varied from 4.8-9.3 dB within the flat gain region. The triple-pass Erbium-doped fiber amplifier has been enhanced by utilizing distribution pumping scheme in the configuration. This improvised configuration minimised the cost of the amplifier yet having the comparable performance with the dual-pump configuration. A flat gain of 17.2 dB with the corresponding noise figure below 8 dB was obtained within 1555-1600 nm
Multi-wavelength, nano-second actively mode-locked Yb-fiber oscillator with 100 nm wide Raman broadened spectrum
No full textAn all-normal dispersion, actively mode-locked Yb-fiber oscillator has been demonstrated which delivers multipulsing output with Raman broadened spectrum spanning more than 100 nm. Pulses of nano-second duration at 953.81 kHz repetition rate were obtained due to an elongated cavity consisting of 200 m long single mode fiber introducing high nonlinearity. The individual pulses of the multi-pulsing output corresponded to different wavelengths in the output spectrum and concurrently generated multiple first order Raman Stokes sidebands at close wavelength intervals. This resulted in a smoother broadband spectrum compared to usually obtained Raman broadened spectrum in normal dispersion regime which contains multiple higher order Stokes lines at large wavelength intervals when pumped by a single nano-second pulse. Analysis of the spectral power content revealed that nearly 50% of the output power contained in the Raman band around the 1120 nm region. By amplification of the generated pulses and further non-linear broadening through an ultra-high numerical aperture (UHNA) fiber, a broad spectrum having a wavelength span of nearly 260 nm with 1.5 Watt average power has been demonstrated showing application capability of the designed source
Influence of clay content on microstructure and flexural strength of in situ reaction bonded porous SiC ceramics
No full textThe aim of the present study is to reveal the effects of clay contents on in situ reaction bonding of SiC, phase development, microstructure, porosity and mechanical properties of porous SiC ceramics. Porous silicon carbide (SiC) ceramics are prepared in air at 1400 degrees C for 1 h using alumina as bond phase additive and variable amount of clay as sintering aids and compared their properties. The ceramics prepared with only alumina additive obtained with flexural strength of 28 MPa at porosity 38 vol% without any characteristic peak for mullite. The mullitization was almost completed at 1400 degrees C with addition of 3 wt% clay. It was found that the addition of clay strongly promoted the phase transformation towards mullite at lower temperature. A high flexural strength of 72 MPa was achieved at porosity level of 33 vol% in the sample prepared with 5 wt% clay due to the enhancement of necks at the contacting points. (C) 2019 Elsevier Ltd. All rights reserved
Mesoporous bioactive glasses for bone healing and biomolecules delivery
No full textImpact of bone diseases and injury is increasing at an enormous rate during the past decades due to increase in road traffic accidents and other injuries. Bioactive glasses have excellent biocompatibility and osteoconductivity that makes it suitable for bone regeneration. Researches and studies conducted on several bioactive glasses gives an insight on the need of multi -disciplinary approaches involving various scientific fields to attain its full potential. Of late, a next generation bioactive glass called as mesoporous bioactive glass (MBG) has been developed with higher specific surface area and control over mesoporous structure that presents a new material for bone regeneration. A brief discussion and overview on the potential use of MBG as a suitable material for bone tissue regeneration and biomolecule delivery is included. Additionally, possible control of the structural and functional property based on composition and fabrication techniques are also covered. According to recent researches, MBG-implant interaction with bone forming cells for cellular growth and differentiation as well as its effect on delivery of growth factor, both in vitro and in vivo, are optimistic; yet, the complete efficacy of this material is still to be explored. Hence, in this article we will review the current development and its applications for bone tissue engineering (TE)
Removal of As(V), Cr(VI) and Cu(II) using novel amine functionalized composite nanofiltration membranes fabricated on ceramic tubular substrate
No full textNovel amine functionalized composite membranes were prepared over tubular ceramic substrate using facile dip-coating and cross-flow filtration approach. The two fabricated membranes, P-60S and P-60S-EDTA with polyethyleneimine (PEI) and EDTA-modified PEI as functional layers respectively, were characterized in terms of EDX, FTIR, XPS, FESEM, AFM and contact angle analyses which confirmed their stable physical and chemical structure for use in high pressure application. Clean water permeability and MWCO study revealed the superior permeability and rejection efficiency of the P-60S-EDTA compared to the P-60S membrane. Incorporation of bulky EDTA molecules in the membrane functional layer simultaneously decreased pore size and increased membrane hydrophilicity. The removal of As(V), Cr(VI) and Cu(II) heavy metals by both membranes were found to be highly pH dependent and overall rejection improved in case of P-60S-EDTA membrane [99.82% for Cu(II), 96.75% for As(V) and 97.22% for Cr(VI)]. Interestingly, rejection of As(V) and Cr(VI) was significantly improved in presence of Cu(II) due to volume resistance provided by EDTA-Cu(II) complex towards the passage of other heavy metal ions. Excellent stability of P-60S-EDTA membrane in continuous operation of 36 h in both ideal and practical water environment suggests its promising application in real field heavy metal contaminated waste water treatment
Large structure-dependent room temperature exchange bias in self-assembled BiFeO3 nanoparticles
No full textWe studied the magnetic properties of self-assembled aggregates of BiFeO3 nanoparticles (similar to 20 nm-40 nm). The aggregates formed two different structures-one with limited and another with massive crosslinking-via the ``drying-mediated self-assembly'' process following dispersion of the nanoparticles within different organic solvents. They exhibit large coercivity H-C (>1000 Oe) and exchange bias field H-E (similar to 350-900 Oe) in comparison to what is observed in isolated nanoparticles (H-C similar to 250 Oe; H-E similar to 0). H-E turns out to be switching from negative to positive depending on the structure of the aggregates, with |+H-E| being larger. Magnetic force microscopy reveals the magnetic domains (extending across 7-10 nanoparticles) as well as the domain switching characteristics and corroborates the results of magnetic measurements. Numerical simulation of the ``drying-mediated self-assembly'' process shows that the nanoparticle-solvent interaction plays an important role in forming the ``nanoparticle aggregate structures'' observed experimentally. Numerical simulation of the magnetic hysteresis loops, on the other hand, points out the importance of spin pinning at the surface of nanoparticles as a result of surface functionalization of the particles in different suspension media. Depending on the concentration of pinned spins at the surface pointing preferably along the easy-axis direction-from greater than 50% to less than 50%-H-E switches from negative to positive. Quite aside from the bulk sample and isolated nanoparticle, nanoparticle aggregates-resulting from surface functionalization-therefore offer remarkable tunability of properties depending on structures