Structural Modifications and Extended Spectral Response of CeO2/CoPc Nanocomposites for Potential Applications

CeO₂/CoPc nanocomposites were synthesized by simple chemical method. Thermal behavior of these nanocomposites was studied by thermogravimetric and differential thermal analysis. The as‐synthesized nanocomposite samples were characterized by various techniques. A decrease in band‐gap energy together with an improved absorption intensity of the composite material confirms the role of the cobalt phthalocyanine in the absorption properties of CeO₂/CoPc composite. This study confirms structural modifications and extended spectral response of the synthesized CeO₂/CoPc nanocomposites. The results demonstrate that CeO₂/CoPc nanocomposite samples are promising materials for organic light‐emitting diodes, solar cells, and optoelectronic devices.     

Computational study on heat transfer and MHD-electrified flow of fractional Maxwell nanofluids suspended with SWCNT and MWCNT

Recent developments in fluid dynamics have been focusing on nanofluids, which preserve significant thermal conductivity properties and magnify heat transport in fluids. Classical nanofluid studies are generally confined to models described by partial differential equations of an integer order, where the memory effect and hereditary properties of materials are neglected. To overcome these downsides, the present work focuses on studying nanofluids with fractional derivatives formed by differential equations with Caputo time derivatives that provide memory effect on nanofluid characteristics. Further, heat transfer enhancement and boundary layer flow of fractional Maxwell nanofluid with single-wall and multiple walls carbon nanotubes are investigated. The Maxwell nanofluid saturates the porous medium. Also, buoyancy, magnetic, electric, and heating effects are considered. Governing continuity, momentum, and energy equations involving Caputo time-fractional derivatives reduced nondimensional forms using suitable dimensionless quantities. Numerical solutions for arising nonlinear problems are developed using finite difference approximation combined with L1 algorithm. The influence of involved physical parameters on flow and heat transfer characteristics is analyzed and depicted graphically. Our simulations found out that surface drag of Maxwell nanofluid with single-walled carbon nanotubes dominates nanofluids with multiple walls carbon nanotubes, but the reverse trend is noticed for larger Grashof number values.     

Thermal performance of straight porous fin with variable thermal conductivity under magnetic field and radiation effects

The present numerical study reports the thermal performance of the straight porous fin with temperature-dependent thermal conductivity, radiation, and magnetic field effects. The heat transfer model comprising the Darcy's law for simulating flow with solid-fluid interactions in porous medium, Rosseland approximation for heat transfer through radiation, Maxwell equations for magnetic field effect and linearly varying temperature dependent thermal conductivity, results into highly nonlinear ordinary differential equation. The governing equation is solved using a finite difference scheme with suitable boundary conditions. The obtained solutions are physically interpreted by considering the impact of different nondimensional parameters on thermal performance, efficiency, and effectiveness of the system through plotted graphs. A detailed result with regard to the Nusselt number at the fin base is calculated. The results obtained are observed to be in excellent agreement with previous studies. From the study, it is observed that there is a significant effect on the thermal performance of the fin in the presence of porous constraints; also, results reveal that the nonlinear thermal conductivity parameter strengthens the thermal performance, efficiency, and effectiveness of the fin. Furthermore, the results of the study reveal that the rate of heat transfer of the fin increases with the increase in the magnetic parameter and radiation parameter.     

Optimally configured convolutional neural network for Tamil Handwritten Character Recognition by improved lion optimization model

Multimedia Tools and Applications - In recent data, Optical character recognition (OCR) systems have laid hands in the field of most popular language recognitions. Unlike other languages, the Tamil...     

Fungal colonization and biochemical changes in coffee beans undergoing monsooning

Changes in the mycofloral composition and concentrations of proteins, reducing sugars, phenols and tannins in coffee beans were analysed during different weeks of monsooning in Coffea arabica L. (Arabica) and C. canephora Pierre ex Froehner (Robusta). The highest fungal populations occurred during the fourth to seventh week of the monsooning process and the dominant fungal species were Aspergillus niger, Aspergillus tamarii, Aspergillus candidus, Penicillium spp. and Absidia heterospora. The protein and reducing sugar content increased steadily while the tannin content decreased beyond the detectable limit during monsooning. The phenolic content, however, was found to decline in the case of Robusta and increase slightly in Arabica. Throughout the study the monsooned coffee beans had different mycoflora and varied biochemical composition compared to non-monsooned coffee beans.     

Production of an antimicrobial compound by <Emphasis Type="Italic">Bacillus subtilis</Emphasis> LS 1–2 using a citrus-processing byproduct

The aim of this study was to investigate the antimicrobial activity of Bacillus subtilis LS 1–2 grown on citrus juice waste (CJW). Citrus-juice waste (CJW) was obtained from the residue of squeezed citrus fruits. To use CJW as a raw material for the growth of B. sutilitis, a citrus-juice medium (CJM) was prepared by treating CJW with Ca(OH)₂. No antimicrobial activity was observed either in the culture broth of Luria Broth medium or in CJM itself. The maximum antimicrobial activity was obtained after 24 hr of cultivation (culture) of Bacillus sutilitis LS 1–2 in CJM. The culture supernatant exhibited inhibitory activity against E. coli O-157 (140 AU/mL), Staphylococcus aureus (180 AU/mL), and Candida albicans (260 AU/mL), respectively. Bacillus subtilus LS 1–2 also produced protease (3,600 U/ml) and amylase (290 U/ml) in CJM. Antimicrobial activity of the culture broth was stable for 1 hr at 100 °C, pH 2–10, and bile acid (concentration needs, 1 mM TDOC and 0.27 mM DOCmM), respectively. These results indicate the potential of CJW as a novel bioresource and the scope of probiotic applications of Bacillus subtilis LS 1–2 in various industrial applications.     

Hydrothermal processing of hydrogen titanate/anatase-titania nanotubes and their application as strong dye-adsorbents

The nanotubes of pure hydrogen titanate and anatase-titania have been synthesized via hydrothermal treatment of as-received anatase-titania particles. The formation mechanism of anatase-titania nanotubes via hydrothermal has been discussed in detail in view of the finger-prints produced by characterizing the intermediate and end products using various microscopic and spectroscopic techniques such as scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, Brunauer, Emmett, and Teller specific surface-area measurement, Fourier transform infrared spectroscope, diffuse reflectance, photoluminescence, thermal gravimetric and differential thermal analyses. The obtained results strongly support the rollup mechanism, involving multiple nanosheets, for the formation of anatase-titania nanotubes with the formation of different intermediate hydrothermal products having various morphologies such as sodium titanate having aggregated rectangular block-like structures, hydrogen sodium titanate and pure hydrogen titanate having highly aggregated unresolved fine-structures containing nanotubes, and finally, the pure anatase-TiO2 nanotubes. It is demonstrated that, during the hydrothermal treatment, the nanotubes of pure hydrogen titanate are formed first coinciding with the stable solution-pH during washing, indicating the completion of ion-exchange process, and a drastic increase in the specific surface-area of the hydrothermal product. The anatase-titania nanotubes are then derived from the pure hydrogen titanate nanotubes via thermal treatment. The use of pure hydrogen titanate and anatase-titania nanotubes for an organic textile dye-removal, from an aqueous solution under the dark condition, via surface-adsorption mechanism has been demonstrated. It is shown that, the specific surface-area and the surface-charge govern the maximum dye-absorption capacity of the anatase-TiO2 nanotubes under the dark condition.     

Impact of gamma irradiation on the monsooning of coffee beans

Monsooned coffee is a special coffee produced only in India. As the process is carried out during the monsoon period, the time taken for monsooning is dependent on rainfall and atmospheric humidity. Traditional methods employed in the monsooning process favour growth of microorganisms, which may affect the quality of the produce. The present study aimed to understand the role of microorganisms in the monsooning process. Coffee beans (both Arabica and Robusta variety) were subjected to irradiation treatments of 5 kGy (kilo Gray) and 10 kGy doses in order to achieve the above objective. Irradiation led to reduction of natural mycoflora with the 10 kGy dose being more efficient than the 5 kGy dose. Aspergillus niger was found to be the dominant fungus colonising the beans prior to monsooning, whereas A. ochraceus was found dominant during the course of monsooning. The other commonly encountered fungi were species of Aspergillus, Penicillium, Absidia, Syncephalastrum, Mucor and Rhizopus occuring at low numbers. At the start of the monsooning process, irradiated samples showed negligible numbers of microorganisms and also lesser number of fungal species during monsooning compared with the non-irradiated samples. Non-irradiated samples took five weeks for the completion of monsooning compared with two weeks for irradiated samples and hence it may be inferred that microorganisms may be playing a minimal role in monsooning.     

Silica‐Based NTPC‐Fly Ash for Dye‐Removal Application and Effect of Its Modification

Silica‐based fly ash (FA) received from the National Thermal Power Corporation (NTPC), India has been utilized for determining its dye‐adsorption capacity. The dye adsorption using the NTPC‐FA has been examined by varying the initial methylene blue dye concentration (7.5–150 μM) and initial solution‐pH (2.5–11.5). The dye‐adsorption capacity of NTPC‐FA has been found to be 0.43 mg/g. To increase the dye‐adsorption capacity, the NTPC‐FA is subjected to the hydrothermal treatment and typical washing cycles without and with the coating of sol–gel derived anatase‐titania. The hydrothermally treated NTPC‐FA and hydrogen titanate–silica composite thus obtained exhibit dye‐adsorption capacity higher than that of NTPC‐FA.     

Chemical synthesis,structural characterization and electrical studies of nanoceria for CMOS applications

Cerium oxide nanoparticles were synthesized using cerium nitrate hexa hydrate and ammonium carbonate as precursors. Structural characterizations were done using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystallite size and lattice strain on the peak broadening of CeO₂ nanoparticles were studied using Williamson-Hall (W-H) analysis. The dielectric properties of nanocrystalline CeO₂ samples with different calcination temperatures, and frequencies have been studied over a temperature range from 303 to 423 K. It is found that the dielectric constant and dielectric loss for all temperatures have high values at low frequencies, which decreases rapidly as frequency is increased and attains a constant value at higher frequencies. The room temperature dielectric constant ε′ obtained for the as prepared CeO₂ nanoparticle sample is 61, which constitutes the highest value ever reported at low frequency. A.C. conductivity, which was derived from dielectric constant and loss tangent data, has a low value at smaller frequencies that increases as the frequency is increased. The dielectric constant and a.c. conductivity values are shifted upwards as the temperature is raised. However, these values are decreased as the annealing temperature is increased. The desired structural properties and high dielectric constant of nanophase CeO₂ make it as a promising material for the high dielectric constant dielectric gate in complementary metal oxide semiconducting (CMOS) devices.