Simulation of a MOS or MIS structured Spatial Light Modulator for Terahertz (THz) Imaging

A large area, square-gate Metal-Oxide/Insulator-Semiconductor (MOS or MIS) structured `Spatial Light Modulator\u27 has been proposed for the Terahertz (THz) imaging at room temperature. This theoretical study has been done entirely by using the MATLAB platform. The 1D Poisson\u27s equation has been solved iteratively by Euler\u27s method with the exact Fermi-Dirac integral for n-doped Si-MOS and GaAs- MIS capacitors in deep accumulation mode. Free carrier density and the potential profile have been found for the degenerate case. The results have been compared with the analytical method, which is approximated by Boltzmann statistics, and clearly, show the difference between the degenerate case and non-degenerate Boltzmann approximation at higher bias. Then the sheet carrier density was calculated by performing the numerical integration over the depth of accumulation. The mobility was calculated for various scattering mechanisms at room temperature, and the total mobility was found by using Matthiessen’s rule. The mobility and free carrier density were then used for calculating the bulk conductivity of the device. The sheet conductance and sheet resistance were found by the numerical integration of the bulk conductivity over the depth of accumulation. The sheet resistance is the DC resistance and was scaled to THz frequencies by using the Drude model. Then a lossless two-port transmission line model was adopted for studying the transmittances of the THz signal through the MOS or MIS devices for different bias and doping concentration and calculated the depth of modulation was calculated Vs frequency between 0.1 and 1 THz. In contrast to the GaAs-MIS device, it has been found that the depth of modulation of the Si-MOS device is much higher. The switching time has been calculated as the 10% to 90% charging time of the interface capacitor by solving the equivalent large-signal RC circuit. The GaAs-MIS displays lower switching time than Si-MOS because GaAs-MIS offers lower interface capacitance than that of the Si-MOS at the same interface bias. The 3dB bandwidth of the modulator has been estimated by assuming the linear RC circuit relations. Although the GaAs-MIS exhibited higher bandwidth than that of Si-MOS, both devices are still promising for the possible fabrication of spatial light modulator for THz imaging

Electronic Opinion Analysis System for Library (E-OASL)

This paper demonstrates a new algorithm for Electronic Opinion Analysis System (E-OASL) for university library where it can analyze the user opinion on library and categorized it in different classification such as positive, negative, neutral and suggestions. The system also shows the percentage of each classification as system output. Our proposed algorithm is based on hybrid approach of sentiment analysis where machine learning's rule-based classifier and lexicon approach's corpus datastore are utilized. We needed to collect around 1200 raw data from the different types of user who are using university library to build our algorithm. The system integrates MySQL database for faster and better data processing. The paper also shows the evaluation of the E-OASL which showed satisfactory result of effectiveness and efficiency of EOASL compare to manual opinion analysis approach

Plankton dynamics and physico-chemical parameters: A longitudinal investigation in carp and catfish culture ponds

An experiment was aimed to discover the overall scenario of physico-chemical parameters along with the qualitative and quantitative analysis of plankton in two different fish culture systems as carp mixed culture and catfish (Pangus) monoculture from September 2021 to February 2022 using conventional techniques. The mean values of transparency and dissolved oxygen (DO) noted at the catfish culture pond were lower than those at the mixed carp culture pond while pH mean values were observed to be higher in the catfish culture pond than in the mixed carp culture pond. A total of 21 genera of phytoplankton were found in both ponds under the groups of euglenophyceae (4), cyanophyceae (4), bacillariophyceae (5) and chlorophyceae (8). Among zooplankton, 13 genera were identified including Rotifera (7), copepoda (2), cladocera (3) and crustacean larvae (1) were recorded in mixed culture ponds whereas in catfish culture ponds, 11 zooplankton genera were recorded including Rotifera (5), copepoda (2), cladocera (3) and crustacean larvae (1). Planktonic abundances were statistically significantly different between the different levels (phytoplankton abundance in CCP, phytoplankton abundance in MCP, zooplankton abundance in CCP, zooplankton abundance in MCP), χ2(3) = 220.46, p < 0.001. Mixed culture pond cyanophyceae, bacillariophyceae, and euglenophyceae are positively associated with water temperature and pH but negatively correlated with DO. Rotifera is negatively associated with catfish culture pond water temperature, whereas chlorophyceae and cyanophyceae are favorably. Catfish monoculture ponds had higher phytoplankton abundance, so phytoplankton grazing fish species could be included with pangus culture to maintain a better water quality

Phytochemical and Biological investigations of Phoenix paludosa Roxb.

ABSTRACT: Lupeol (1), epilupeol (2) and β-sitosterol (3) were isolated from the n-hexane and the carbon tetrachloride soluble fraction of a methanol extract of the leaves of Phoenix paludosa Roxb. The n-hexane, carbon tetrachloride and chloroform soluble materials from the concentrated methanol extract were subjected to antimicrobial screening and brine shrimp lethality bioassay. All of the partitionates showed insensitivity to microbial growth, while the n-hexane, chloroform and methanol soluble fractions showed significant cytotoxicity having LC50 2.17 µg/ml, 2.77 µg/ml and 2.46 µg/ml, respectively. This is the first report of isolation of the compounds 1-3 and bioactivities of P. paludosa

Preliminary pharmacological screening of Bixa orellana l. leaves

Preliminary pharmacological studies were performed on the methanol extract of Bixa orellana L. (Bixaceae) leaves to investigate neuropharmacological, anticonvulsant, analgesic, antidiarrhoeal activity and effect on gastrointestinal motility. All studies were conducted in mice using doses of 125, 250 and 500 mg/kg of body weight. In the pentobarbitone-induced hypnosis test, the extract statistically reduced the time for the onset of sleep at 500 mg/kg dose and (dose-dependently) increased the total sleeping time at 250 and 500 mg/kg dose. A statistically significant decrease in locomotor activity was observed at all doses in the open-field and hole-cross tests. In the strychnine-induced anticonvulsant test, the extract increased the average survival time of the test animals (statistically significant at 250 and 500 mg/kg). The extract significantly and dose-dependently reduced the writhing reflex in the acetic acid-induced writhing test. Antidiarrhoeal activity was supported by a statistically significant decrease in the total number of stools (including wet stools) in castor oil-induced diarrhoea model. A statistically significant delay in the passage of charcoal meal was observed at 500 mg/kg in the gastrointestinal motility test. The extract was further evaluated in vitro for antioxidant and antibacterial activity. It revealed radical scavenging properties in the DPPH assay (IC50 = 22.36 μg/ml) and antibacterial activity against selected causative agents of diarrhoea and dysentery, including Shigella dysenteriae