Polystyrene is extensively used in building and construction industry, packaging and transportation of fragile equipment due its low density, high melting point, low thermal conductivity, low water absorption, etc. Polystyrene after usage is usually discarded thereby causing environmental problems. The post-usage of polystyrene has, therefore, been a subject of intense research in recent times. The aim of this work is to produce adhesive from polystyrene wastes. Polystyrene waste (PS) was collected, processed and dissolved in tackifyer and formulated with diphnyle amine and diethylene glycol dibenzoate additives to produce adhesive using 3 levels variables factors and 4 levels testing factors of design expert optimization software. The produced adhesive was further characterized for viscosity, pH, percentages solid and moisture contents for their response surfaces. The results showed that the best fit viscosity for each run was Run 1B> Run 5A > Run 5D> Run 5B>Run 4D based on the regression analysis and analysis of variance (ANOVA). The pH values obtained ranged from 4.0 to 6.3; percentage moisture content was in the order of Run 1B < 5A<4D<4B and percentage solid content was in the order of Run 1B<5A<4D. The best fitted adhesive was run 1B with 5.93 % moisture content; 5A has 7.57 % moisture content and 4D with 8.76% moisture content. The percentage solid content; Run 1B has 67.19 %, 5A has 68.16 % and 4D has 75.50 %. The produced adhesives were found within the standard range of adhesives used in production of particleboard.

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With the explosive increase in the data traffic of wireless communication systems and the scarcity of spectrum, terahertz (THz) frequency band is predicted as a hopeful contender to shore up ultra-broadband for the forthcoming beyond fifth generation (5G) communication system. THz frequency band is a bridge between millimeter wave (mmWave) and optical frequency bands. The contribution of this paper is to carry out an in-depth study of the THz channel impairments using mathematical models to evaluate the requirements for designing indoor THz communication systems at 300GHz. Atmospheric absorption loss, diffraction loss and free space path loss were investigated and modeled. Finally, we discuss several potential application scenarios of THz and the essential technical challenges that will be encountered in the future THz communications. Finally, the article finds that propagating in the THz spectrum is strongly dependent on antenna gain.

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Abstract The aim of this study was to evaluate the adsorption dynamics of crab shell chitosan/neem leaf composite against methylene blue dye at varying concentrations (50 and 200 mg/L), bed depths (2.5 and 5.0 cm), and flow rates (2.17 and 2.90 mL/min). The chitosan composite has a specific surface of 258 m2/g. Its surface is rich in amine/amide groups. The results reflect better dye adsorption at higher operating conditions. The maximum dye adsorption capacity observed was almost 77 mg/g. The kinetics models showed good correlation with the experimental data and described the breakthrough behaviour of dye removal. The Thomas model predicts external and internal diffusion as the rate controlling mechanisms, while the Adams-Bohart model indicates a simultaneous steady state process of intraparticle diffusion and ionic interaction. Chitosan composite is a promising adsorbent candidate for dye wastewater treatment.