An ultra-low material loss ellipse core-based photonic crystal fiber for terahertz wave guiding: design and analysis

In this research work, we report a new design model of quasi-shaped cladding areas with rotated-hexa-based elliptical shaped core areas in photonic crystal fiber (Q-PCF) for terahertz waves of communication signals. Here, we present a six-layer circular air hole in the quasi-shape of cladding regions with two layers of rotated-hexa-based elliptical shaped air holes in the core regions of the Q-PCF for analysis of communication networks in the terahertz regime. Additionally, perfectly matched layers and the finite element method based on the COMSOL software are used to design this Q-PCF. For short- and wideband communication sectors, our proposed Q-PCF is highly useful, as it reduces ultralow effective material loss (EML), confinement loss, and scattering loss in the terahertz regime. After analysis of the numerical results, our suggested Q-PCF shows an ultralow EML of 0.0159 cm^?1, power fraction in the core area of 74%, large effective area of 5.49?×?10^–8 m², confinement loss of 3.22?×?10^–12 cm^?1, and scattering loss of 1.23?×?10^–10 at 1 THz frequency. Moreover, our proposed Q-PCF demonstrates single-mode propagation by the graphical results of the V-parameter over a frequency range of 0.80–3 THz. Our results suggest, we can clearly say that the reported Q-PCF may be highly appropriate for terahertz wave propagation for many communication networks.

     

Biodegradation and detoxification of wood leachate from pentachlorophenol-treated poles

The pentachlorophenol (PCP) in leachate, generated from size-reduced PCP-treated poles, was degraded using a mixed culture containing Arthrobacter sp. in cyclic batch bioreactors in non-sterile conditions. Complete degradation of PCP was achieved for a five-month period for a concentration of 50 mg PCP/L and 12 h cycle time. The adsorbable organic halogen (AOX) concentration of the reactor effluent was reduced by two orders of magnitude compared to the feed, and the chemical oxygen demand (COD) was reduced by 50%. The increase in chloride ion concentration also suggests that PCP was mineralized to end products. In tests to increase the process throughput, complete degradation of PCP was also achieved in the cases for 120 mg PCP/L and a 12 h cycle time or 50 mg PCP/L and a 6 h cycle time. Daphnia magna toxicity tests showed that the presence of PCP in leachate caused toxicity, and the biodegradation of PCP resulted in significantly reducing the effluent toxicity to a value similar to that of PCP-free nutrient solution.     

Electrocoagulation (EC)--science and applications

Although electrocoagulation is an evolving technology that is being effectively applied today for wastewater treatment, the paucity of scientific understanding of the complex chemical and physical processes involved is limiting future design and hindering progress. The objective of this review through a survey of the literature is to bring the chemistry and physical processes involved into perspective and to focus attention on those areas critically needing research.     

Synthesis and characterization of sulfonated bromo-poly(2,6-dimethyl-1,4-phenylene oxide)-co-(2,6-diphenyl-1,4-phenylene oxide) copolymer as proton exchange membrane

Novel polymer electrolyte membranes containing the sulfonic acid groups attached on polymer backbone and side group simultaneously were synthesized. The bromo-poly(2,6-dimethyl-1,4-phenylene oxide)-co-(2,6-diphenyl-1,4-phenylene oxide) copolymer (BrcoPPO) was prepared by oxidative coupling polymerization with 2,6-dimethyl phenol, 2,6-diphenyl phenol, CuCl(I) and pyridine, and followed by bromination with bromine. Copolymer was maintained in 2,6-diphenyl phenol 10 mol% and 2,6-dimethyl phenol 90 mol%. Sulfonation of BrcoPPO (S-BrcoPPO) was carried out in a chlorobenzene solvent using chlorosulfonic acid. The polymeric membranes were cast from dimethylsulfoxide solution. The membranes were studied by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. S-BrcoPPO membranes exhibited proton conductivities from 2.3 × 10⁻³ to 1.4 × 10⁻² S/cm, water uptake from 7.00 to 49.43%, IEC from 0.58 to 1.38 mequiv./g, methanol permeability from 1.9 × 10⁻⁷ to 3.5 × 10⁻⁷ cm²/S.     

Synthesis and properties of multihydroxy soybean oil from soybean oil and polymeric methylene‐diphenyl‐ 4,4′‐diisocyanate/multihydroxy soybean oil polyurethane adhesive to wood

The reactive multihydroxy soybean oil (MHSBO) was synthesized from epoxidized soybean oil (ESBO). The ESBO was reacted with ethylene glycol to obtain MHSBO having high functionality. This study investigated a feasibility to prepare wood adhesive through the reaction of polymeric methylene‐diphenyl‐4,4′‐diisocyanate (pMDI) with MHSBO. Different polyurethane adhesives were prepared with a variety of equivalent mole ratios (eq. mole ratios) of MHSBO to pMDI. The chemical reactions of adhesives were analyzed using ¹H NMR and Fourier transform infrared (FTIR), and their thermal studies were investigated by DSC and TGA. The MHSBO/pMDI resins (3 : 1 and 2 : 1 eq. mole ratios) showed endothermic peaks, whereas the MHSBO/pMDI resins (1 : 2 and 1 : 3 eq. mole ratios) showed exothermic peaks. The best adhesion strength was found when plywood was bonded with the adhesive of a eq. mole ratio of 2 : 1 (MHSBO : pMDI). These results indicated that the bond strength was not related to the reactivity obtained from the FTIR spectra. But it was explained that the adhesion strength increased as the residual  NCO groups in the adhesive reacted with the hydroxy groups of wood during the manufacturing of plywood. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Phenolic acids in the jute plant (corchorus capsularis)

The bark and the stem of unretted jute plant (Corchorus capsularis) were found to contain various free, glycosidic and ester-linked phenolic acids. From an 80% aqueous ethanol extract, p-coumaric, ferulic, caffeic, vanillic and p-hydroxybenzoic acids were identified and quantified. p-Coumaric acid, the major component, and β-sitosterol were isolated and characterised.