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In this paper, the effect of two options (first option: fluidized bed drying (120–160 °C) + sun drying; second option: fluidized bed drying (120–160 °C) + again fluidized bed drying (65 ± 2 °C)) of two-stage drying on kinetics, energy consumption, quality of dried maize as color, nutritional properties, and hardness was evaluated to assess the drying performance. First stage drying for both options was executed by FBD at 7.0 cm bed thickness within the temperature range of 120–160 °C for 1.5–4 min. Then, the samples were tempered for 45 min in a closed container after completion of first stage drying. Second stage drying was then done by sun drying method (temperature: 33–36°C, RH: 52–65%, air velocity 0.4–0.6 m/s) for first option while for second option, it was accomplished again by FBD (65 ± 2°C). Drying time was shorter in the case of second option (2.23 h) than first option (4.98 h). Effective moisture diffusivity was found higher in both options of two-stage drying (10.5 × 10−09 m2/s to 63 × 10−09 m2/s) than control drying. Specific energy consumption was lower in first option compared to second option. Color of dried maize in two-stage options deteriorated markedly. However, nutritional qualities of dried grain for two-stage drying technique were similar to control sample. Hardness of the two-stage dried maize was lesser than control product. The two-stage drying options of maize drying instead of conventional sun drying method can be considered an alternative drying technique for the commercial maize drying industries.

In this paper, the tunability of the fluorescence capacity of ZnS quantum dot (QD) after the effective doping of transition metal iron (Fe) have been studied. The structural, electronic, and optical properties have been optimized for pure and Fe doped ZnS QDs by using local density approximation in density functional theory framework. The optimized lattice volumes show a reasonable agreement with previously obtained experimental and theoretical data for both the doped and un-doped system. As Fe is doped to ZnS, the crystal system transforms from cubic to tetragonal structure with an increased lattice volume compared to the pure system and exhibits a narrow band gap with a negative value. Moreover, the absorption peak is broadened in the ultraviolet to the blue (visible) region and it shows a low intense peak in the infrared region. These results indicate the increase of fluorescence capacity that may be expected to apply for rapid detection of virus-like as SARS CoV-2. © 2021 Wiley Periodicals LLC.

In this paper, the effect of high concentrated Iron (Fe) doping on the structural, electronic and optical properties of Barium Titanate (BaTiO3) based on density functional theory (DFT) are reported. The calculated lattice parameters show that the phase of BaTiO3 transformed into tetragonal from cubic phase after Fe doping. The electronic structure shows that Fe creates some defect states in the energy band which create weak coordinate covalent bond because of metal-metal interaction. The complex dielectric function, absorption, reflectivity, refractive index, optical conductivity and energy-loss spectrum for BaTiO3 and Fe doped BaTiO3 are calculated, and the results show a dramatic behavior near Fermi level after Fe doping.

Compact load cells have been developed using multiwall carbon nanotube/cotton (MWCNT/cotton) composites, whose performance has been optimized by varying the concentration of MWCNTs and the thickness of the composite. The sensitivity of the load cell, which is defined as the ratio of the change in the relative electric resistance to the change in applied pressure, is measured to be in the range of 180-0.20 kPa-1 for applied pressures of 8.84 Pa-884 kPa (F=1.0 mN-100 N). The load cells show a rapid response in situations with a frequently changing force, with response times τ1/2 of 4.5 and 5.0 ms for the application and release of load, respectively. The load cell demonstrates high reproducibility in tests involving more than 11,200 compression/relaxation cycles. It also has high reproducibility in different harsh environments and has a good electric-conductance recovery property. The load cell is successfully used to monitor the time-varying center of gravity of a human foot, which can be applied to the diagnosis of sick and healthy people. The MWCNT/cotton load cells can be used as wearable and flexible devices for monitoring human health.

Synthesis of plasma polymerized cyclohexane (PPCHex) thin films on to glass substrates has been done using a capacitively coupled parallel plate low-pressure glow discharge technique from cyclohexane at room temperature. From scanning electron microscopy, smooth and homogeneous surface of PPCHex thin films is observed and atomic force microscopic micrographs show the roughness of 0.815 to 0.364 nm which also confirm the smooth, homogenous, pinhole free and uniform surface of the PPCHex thin films. The presence of 73.1 and 74.7 percentage of carbon in PPCHex thin films of thicknesses 220 and 350 nm with a small percentage of oxygen is confirmed by the energy dispersive x-ray analysis. The PPCHex thin film is thermally stable up to about 510 K. The structure of PPCHex thin films is observed to vary with film’s thickness by forming new chemical bonds such as O-H stretching, C=C stretching, C≡C stretching, C-O stretching compared to that of the monomer. Allowed direct band gaps of PPCHex thin films are found between 2.97 and 3.61 eV for different thicknesses and allowed indirect band gaps are found to be 1.83 to 2.31 eV. Therefore, the PPCHex could be used in different type of optoelectronic devices.

Structural, electronic, optical, and thermal properties of undoped and metal, M (Ni, Cu, and Zn), doped cadmium iodide (CdI2) were studied using a generalized gradient approximation of density functional theory. Lattice constants found from the theoretical studies of the structure of the undoped and doped CdI2 are in good agreement with those found in the available experimental and theoretical investigations. A strong mixing of I 5p and M 3d states is found after the doping of 3d M in CdI2, which alters the bandgap from positive to negative. Among all M (Ni, Cu, and Zn), Ni doped CdI2 with a narrow negative bandgap evolve the quantum dot level. Due to interactions between the Cd 4d and M 3d states, the measured optical and thermal properties of the doped system assessed with pure CdI2 indicate unusual behaviors, which suggest that the material can be used in different nano-electronic and electrochemical applications and in biological levels such as detection of COVID-19 pathogens.

Highly sensitive pressure sensors have been developed from multiwall carbon nanotube (MWCNT) coated cotton fibers to utilize them in monitoring of human activities. The sensing mechanism is discussed through experimental and theoretical explanations. The principle of the sensing mechanism is related with the number of contacts among the MWCNT coated fibers and contact area among the fibers when a force is applied. Using the three sensors a foot pressure sensor system has been developed, which can detect the exerted force of human foot during standing, walking, running, jumping, and other activities. The locus of the center of gravity is also measured by these sensors during these human activities. The exerted force increases instantaneously when a person jumps from an upper step of a ladder onto a floor, which is clearly recorded. The foot pressure sensors can be used to monitor the real-time sporting performances. To prevent the ankle and knee injury of sportsmen and to monitor the activities of the patients, and old persons, the foot pressure sensors can be utilized.

High-performance plasma polymerized organic thin films have been synthesized by employing a capacitively coupled glow discharge technique and cyclohexane is used as a precursor material. The surface of the plasma polymerized cyclohexane (PPCHex) thin films observed to be smooth, pinhole free and uniform. It is observed from thermal analysis that the rate of loss of mass is very low in air atmosphere below 510 K and the films are thermally stable. Above 510 K weight loss takes place in different stages in air. The current density of the PPCHex thin films is increased when the thicknesses is decreased and that is increased with increasing temperatures. The conduction mechanism of carrier transport operative in these PPCHex thin film is dominated by Schottky type conduction mechanism. The activation energy of the PPCHex thin films for applied voltage 10 V is found 0.14 ± 0.05 eV near room temperature region and that in the higher temperature region is 0.57 ± 0.04 eV. The activation energy in the Schottky region for the applied voltage 50 V is about 0.16 ± 0.06 eV near the room temperature region and that is 0.83 ± 0.05 eV at the higher temperature region.

Biomass is one of the predominant renewable energy sources and the use of biomass for the energy generation has got much attention due to its environmental friendliness. Densification of coir dust into fuel briquette can solve waste disposal problem as well as can serve as an alternative energy source. The objective of this study was to investigate the possibility of producing briquette from coir dust and rice husk blend without binder. During this study, a briquetting experiment was conducted with different coir dust and rice husk blends (i.e. coir dust and rice husk ratio of 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100). Briquetting operation was performed using a die-screw press type briquetting machine. The briquettes were tested to evaluate their density, compressive strength, calorific value, burning rate and water vaporizing capacity and it was found that mixing ratio had a significant effect on the physical, mechanical and combustion properties of the coir dust-rice husk briquettes. Density, compressive strength and calorific value and water vaporizing capacity were increased with increasing mixing ratio while burning rate was decreased. Coir dust-rice husk briquettes with mixing ratio of 20:80 had higher density (1.413 g/cm3), compressive strength (218.4 N/cm2), calorific value (4879 kcal/kg), water vaporizing capacity (0.853 l/kg) and low burning rate (0.783 kg/hour) followed by the mixing ratio 40:60, 50:50, 60:40 and 0:100. The results indicate that coir dust and rice husk blend briquettes were found to have better overall handling characteristics over rice husk briquette. However, production of briquettes from coir dust and rice husk at mixing ratio of 50:50 was found to be more suitable for commercial application in terms of cost effectiveness.

Defective unshu oranges ( Citrus reticulate Blanco var. unshu ) were sorted based on fluorescent imaging technique in a commercial packinghouse but fresh appearing unshu were rejected due to fluorescence appearing on their peel. We studied the various visible patterns based on colour, fluorescence and microscopic images, where even areas of the peel that are not obviously damaged can have fluorescence, to provide a categorization of fluorescence reasons. The categorization corresponded to: 1) hole and flow; 2) influenced by damaged or rotten fruits that have released peel oil onto it; 3) immature or poor peel quality; 4) whitish fluorescence due to agro-chemicals and 5) variation of the growing season. The identification of such patterns of fluorescence might be useful for citrus grading industry to take some initiatives to make the entire automated system more efficient.

Research was conducted to acquire knowledge of the ultraviolet and visible spectrums from 300 -800 nm of some common varieties of Japanese citrus, to investigate the best wave-lengths for fluorescence excitation and the resulting fluorescence wave-lengths and to provide a scientific background for the best quality fluorescent imaging technique for detecting surface defects of citrus. A Hitachi U-4000 PC-based microprocessor controlled spectrophotometer was used to measure the absorption spectrum and a Hitachi F-4500 spectrophotometer was used for the fluorescence and excitation spectrums. We analyzed the spectrums and the selected varieties of citrus were categorized into four groups of known fluorescence level, namely strong, medium, weak and no fluorescence.The level of fluorescence of each variety was also examined by using machine vision system. We found that around 340-380 nm LEDs or UV lamps are appropriate as lighting devices for acquiring the best quality fluorescent image of the citrus varieties to examine their fluorescence intensity. Therefore an image acquisition device was constructed with three different lighting panels with UV LED at peak 365 nm, Blacklight blue lamps (BLB) peak at 350 nm and UV-B lamps at peak 306 nm. The results from fluorescent images also revealed that the findings of the measured spectrums worked properly and can be used for practical applications such as for detecting rotten, injured or damaged parts of a wide variety of citrus.