International Nano Letters

The focus of this work is to study the effect of sodium montmorillonite (MMT-Na) clay content on the rate and extent of enzymatic hydrolysis polyvinyl alcohol (PVA)/starch (S)/carboxymethyl cellulose (CMC) blends using enzyme cellulase. The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without MMT-Na and decreased with the addition of MMT-Na for PVA/S/CMC blend (51.5 μg/ml h), PVA/S/CMC/1% MMT (45.4 μg/ml h), PVA/S/CMC/3% MMT (42.8 μg/ml h), and PVA/S/CMC/5% MMT (39.2 μg/ml h). The results of this study have revealed that films with MMT-Na content at 5 wt.% exhibited a significantly reduced rate and extent of hydrolysis. Enzymatic degradation behavior of MMT-Na containing nanocomposites of PVA/S/CMC was based on the determinations of weight loss and the reducing sugars. The degraded residues have been characterized by various analytical techniques, such as Fourier transform infrared spectroscopy, scanning electronic microscopy, and UV-vis spectroscopy.

In this work, transparent heterojunction between zinc oxide (ZnO) and poly(N-vinyl carbazole) (PVK) was fabricated by solution processing techniques such as spin-coating and dip-coating techniques; then, its performance was studied using current (I)-voltage (V) measurement at room temperature. Before fabricating the heterojunction, initially, the growth characteristics of both thin films were independently optimized on a well-cleaned glass substrate, then its structural properties, optical properties, and surface topography were characterized using an X-ray diffractometer, UV-VIS-NIR spectrophotometer, and atomic force microscope, respectively. The structural analysis confirms the existence of a PVK thin film in amorphous nature and ZnO thin film in hexagonal crystal structure. The transparent nature of the heterojunction was found to be more than 85% in the visible and NIR regions with the absorption onset in the ultraviolet region. The observed experimental results explored the possibilities of fabricating ZnO/PVK transparent heterojunction by solution-based routes on a transparent fluorine-doped tin oxide substrate for transparent electronics applications.

We have systematically studied the relationship between synthesis pH and morphological and optical properties of silica aerogels. We have determined through SEM and BET that there is a systematic correlation between the pH of the initial silica solution and the surface area, porosity, and pore size of the resulting aerogel. We find that optical transmittance, particularly its wavelength dependence (dispersion), is strongly governed by the microstructure and, therefore, synthesis pH. We have determined that the microstructure of the aerogels fall into three broad categories: monostructural, which is characterized by repeating elongated microstructural features; fractal, which shows a distinctive structure that is emulated on multiple length scales; and isotropic, which is characterized by having no distinct features in its microstructure. Simply by controlling the pH of the synthesis environment, we can tune the optical properties of silica aerogels through pH controlled the microstructural modification. We have found that pH = 1–5 gives high dispersion, pH = 6–7 results in low transmittance and low dispersion, pH = 8 shows the highest transmittance with the lowest dispersion, and pH = 9–10 transitions back to lower transmittance and higher dispersion.

The pure titania (TiO₂) and the heterogeneous ternary magnetic nanocomposite of copper ferrite/ferrite oxide (CuFe₂O₄/Fe₂O₃) deposited by titanium dioxide (TiO₂) were fabricated using a facile one-pot hydrothermal synthesis for the photocatalytic decomposition of methylene blue (MB) dye, under visible light. The nanocomposite was encoded as TCF in this work, where T stands for TiO₂, C for CuFe₂O₄ and F for Fe₂O₃. Various techniques such as powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, diffuse reflectance spectroscopy, nitrogen physisorption, and vibrational sample magnetometry (VSM) were used to characterize the prepared samples. The PXRD data showed that the samples had pure anatase structure and the average crystal size of anatase TiO₂ in the pure titania and ternary nanocomposite were calculated 147 Å and 135 Å, respectively. The nitrogen physisorption analysis data showed that the pore diameter was increased from 10.6 nm in pure titania to 16.0 nm in TCF. The pore volume was also increased from 0.316 in titania to 0.383 cm³/g in TCF sample. It also increased the typical magnitude of the mesopores’ diameter and volume per weight but it reduced the specific surface area of the samples. The VSM analysis of the ternary nanocomposite showed a considerable magnetic property of the sample (1.99 emu/g), qualifying it as a paramagnetic material. The photocatalytic decomposition efficiency of MB reached 77% and 68% in the presence of pure titania and TCF ternary nanocomposite, after 240-min exposure by the visible light. Active species trapping experiments showed that the major active species responsible for the photodecomposition of MB in the presence of TCF are $${\text{O}}_{2}^{ \cdot - }$$O2·- radicals and holes (h⁺).

All-inorganic cesium lead bromide (CsPbBr3) perovskite nanoparticles and ZnO nanoparticles were synthesized. The structure, optical properties and the morphology of synthesized nanoparticles were fully characterized using X-ray diffraction (XRD), UV/Vis spectroscopy and transition electron microscopy (TEM). A comparative study was carried out to investigate the antibacterial activity of ZnO and CsPbBr3 perovskite nanoparticles toward Gram-negative, rod-shaped Escherichia coli O157:H7 bacteria cells. Experimental results showed that the antibacterial activity of CsPbBr3 nanoparticles was better than that of ZnO nanoparticles.

In a new theoretical investigation, we study light transmission through a photonic crystal (PC) slab with limited boundaries at width. By using a tight binding model, photon dispersion relation and photon Green function for a perfect system are obtained. Then, based on the Lippmann-Schwinger formalism, we calculate the effects of disordering on light transmission in the PC channel. We found that the ratio of the electric field for a defected system with respect to a perfect system at a peculiar frequency is maximized for the wave vector corresponding to the first Brillouin zone (BZ) edge showing photon localization. The electric field difference of the first and second neighboring sites with respect to the defect site on the first BZ edges are depicted in several plots indicating frequency dependence which can be applicable in frequency filtering or resonating cavity studies.

In this paper, a gallium antimonide junctionless tunnel field-effect transistor based on electrically doped concept (GaSb–EDTFET) is studied and simulated. The performance of the device is analyzed based on the energy band diagram and electric field profile. The on-current, transconductance, and cut-off frequency are enhanced in case of GaSb–EDTFET compared with Si-EDTFET due to the combination of the high tunneling efficiency of the narrow bandgap and the high-electron mobility of GaSb. On the other hand, the Gaussian-doping profile decreases the ambipolar and off current by increasing the tunneling barrier length at the drain/channel interface. Hence, applying Gaussian-doping profile on GaSb–EDTFET makes it a suitable candidate for analog and digital applications. Next, heterostructure channel/source interface EDTFET is studied which uses GaSb for the source and AlGaSb for the drain and channel regions. Then, it has been optimized by numerical simulation in terms of aluminum (Al) composition. The optimal Al composition was founded to be around 10% (x = 0.1). It is shown that the blend of Gaussian-doping profile and the heterostructure channel/source interface with optimal Al composition remarkably reduces ambipolar current amount to a value of 1.3 × 10−23 A/μm. The improvements in terms of Ioff, Ion, Ion/Ioff rate, subthreshold swing, transconductance, cut-off frequency, and also suppressed ambipolar behavior are illustrated by numerical simulations.

MCM-41/CeO2 and MCM-48/CeO2 were synthesized by direct and indirect methods in solvent media and by grinding method in a solvent-free media. The materials prepared by grinding method are characterized by X-ray diffraction, infrared spectrum analysis, and N2 adsorption and desorption. Surface areas and pore size of MCM-48/CeO2 were obtained with values of 680.9 m2·g−1 and 1.64 nm, respectively, by BET method. The results showed that CeO2 nanoparticles were introduced into MCM-41 and MCM-48, and there was formation of CeO2 crystallites as secondary phase in the extra framework of MCM-41 and MCM-48. MCM-41/CeO2 and MCM-48/CeO2 materials are used as photocatalysts in degradation of Congo red as a dye pollutant. The MCM-41/CeO2 and MCM-48/CeO2 prepared by grinding method showed the higher photoreactivity with 97.6 % and 93.1 %, respectively, of degradation of Congo red. The higher photoreactivity is due to the complete incorporation of cerium ions in mesoporous material of MCMs in a solvent-free media.

Present work aims to study the dispersion characteristics of Al2O3 nano-dispersoid in water following different periods of ultrasonication and its impact on the thermal conductivity and viscosity of the nanofluid. Nanofluids with 0.5–2 vol% of Al2O3 nanoparticles have been prepared by ultrasonication for varying period. Al2O3 nanofluids reported a maximum thermal conductivity enhancement of 16.1% for 2 vol% of nanoparticle concentration, after an optimum ultrasonication of 2 h beyond which the thermal conductivity decreases with further ultrasonication. The optimum ultrasonication time required for uniform dispersion of nanoparticles increases with the increase in the Al2O3 volume fraction. For 1.5 vol% Al2O3 nanoparticle loading, the viscosity of nanofluid decreased by 33% with an increase in the sonication time from 30 to 90 min. Further increase in sonication time by 30 min resulted in 13% increase in the viscosity of Al2O3 nanofluid. This decrease in the thermal conductivity enhancement and increase in the viscosity beyond the optimum ultrasonication period have been attributed to the re-agglomeration of nanoparticles which are confirmed by TEM, and DLS results carried out after different instants of ultrasonication. The occurrence of re-agglomeration is explained in terms of the convective flow associated with the ultrasonication process. Various theoretical models like Maxwell or Hamilton–Crosser models which when used to predict the thermal conductivity of nanofluid, underestimate the thermal conductivity. A new correlation is, therefore, developed on the basis of experimental results. With an R2 value of 0.9924, the correlation showed a good agreement with the present thermal conductivity data.