Electronic nose and wireless sensor network for environmental monitoring application in pulp and paper industry: a review.

Pulp and paper industries emit various odorous gases during the pulp production and paper-making phase, which are unpleasant and have harmful effects on the human body. The working staffs are continuously exposed to these gases and develop various health issues. Hence, regular monitoring and analysis of such gases are necessary to avoid any sudden high concentration exposure and to prevent adverse health effects on the staff. An electronic nose (EN) has an array of gas sensors with an alert system for early detection of gases. Various ENs have been developed for varying applications till date. The detailed knowledge of the sensors used, their sensitivity and technology is helpful in development of any EN. The objective of this study is to comprehensively review various developed ENs with respect to their gas sensing and pattern recognition (PR) technologies. The information on gases released from pulp and paper industries is also compiled. The evolution of EN technology, its various applications, challenges in developing EN and its utility in safeguarding the industrial workers' life have been described. Further, gap analysis among previously developed EN, contemporary EN and wireless sensor network (WSN) is elaborated. It will facilitate future researchers for better selection of sensors and PR technologies while developing EN. The commonly used sensing technologies are described with their advantages, disadvantages and working principles. Metal oxide semiconductor (MOS) gas sensor and ANN algorithm show better result and hence recommended in the development of EN, whereas ZigBee protocol has been widely used for WSN.

Synthesis, Structure, and Bonding of 1-Oxa-6,6aλ(4)- chalcogenopentalenes and Related Derivatives; The Role of Intramolecular Coordination.

The synthesis and characterization of a series of alicyclic organochalcogen compounds derived from 2-chloro-1-formyl-3-hydroxymethylenecyclohexene (16) are described. The reaction of 16 with disodium disulfide afforded an unexpected 1-oxa-6,6aλ(4)-dithiapentalene 33, whereas the reaction of disodium diselenide afforded 1-oxa-6,6aλ(4)-diselenapentalene 34, along with 1,6-dioxa-6a-selenapentalene 35. In contrast, when 16 was treated with Na2Te2, it resulted in the formation of 1-oxa-6,6aλ(4)-ditellurapentalene 36 along with 1,6-dioxa-6a-tellurapentalene 37 and cyclic monotelluride 38. The oxidation of 1-oxa-6,6aλ(4)-diselenapentalene 34 with m-CPBA provided the corresponding 1-oxa-6,6aλ(4)-diselenapentalene-6,6aλ(4)-dioxide 39 in which both of the selenium atoms were found to be oxidized. The 1-oxa-6,6aλ(4)-dichalcogenopentalenes 33, 34, and 36 are stabilized by 3c-4e bond resulting from intramolecular E···O interaction. The donor oxygen donates a lone pair of electrons to the σ* orbital of acceptor E-E bond (E = S, Se, and Te) whose σ bond already has its bond pair electrons. The existence of intramolecular E···O interactions was established by multinuclear NMR spectroscopy, single crystal X-ray analysis, and computational studies. The single crystal X-ray structures of compounds 33, 34, and 36 reveal that the molecules are almost planar. Nucleus-independent chemical shifts were calculated to compare the aromaticity in both the five-membered rings of 33, 34, 36 and 1,6-dioxa-6a-chalcopentalenes (35 and 37). The isotropic shift values of the covalently fused five-membered heterocyclic rings are more negative than the five-membered heterocyclic rings formed by intramolecular coordination.

Synthesis, Structure and Antioxidant Activity of Cyclohexene-Fused Selenuranes and Related Derivatives.

Synthesis, structure and antioxidant activity of new cyclohexene-fused spiroselenuranes and a spirotellurane is reported. Oxidation reactions of bis(o-formylcyclohex- 1-ene)selenide/bis(2-hydroxymethylcyclohex-1-ene)selenide provide the corresponding spiroselenuranes. The glutathione peroxidase-like activity of the newly synthesized compounds has been evaluated.

2-Bromo-5-tert-butyl-N-methyl-N-[2-(methyl-amino)-phen-yl]-3-(1-methyl-1H-benzimidazol-2-yl)benzamide.

In the title compound, C27H29BrN4O, benzimidazole ring system and the amide moiety are planar [r.m.s. deviations = 0.016 (2) and 0.017 (1) Å, respectively]. The mol-ecule adopts a conformation in which the amide linkage is almost perpendicular to the central ring [dihedral angle = 85.79 (8)°], while the benzimidazole ring system makes a dihedral angle of 70.26 (11)° with the central ring. In the crystal, the mol-ecules form dimers through N-H⋯O hydrogen bonds and C-H⋯O interactions. These dimers are further linked into zigzag ribbons along [201] by weak C-H⋯Br inter-actions. As a result of the bulky nature of the mol-ecule, as evidenced by the large dihedral angles between rings, there is little evidence for any π-π inter-actions.

Water quality analysis of surface water: a Web approach.

The chemical, physical and biological characteristics of water with respect to its suitability describe its quality. Concentration of pesticides or fertilisers degrades the water quality and affects marine life. A comprehensive environmental data information system helps to perform and complete common tasks in less time with less effort for data verification, data calculations, graph generation, and proper monitoring, which helps in the further mitigation step. In this paper, focus is given to a web-based system developed to express the quality of water in the imprecise environment of monitoring data. Water samples were analyzed for eight different surface water parameters, in which four parameters such as pH, dissolved oxygen, biochemical oxygen demand, and fecal coliform were used for the water quality index calculation following MPCB Water Quality Standards of class A-II for best designated use. The analysis showed that river points in a particular year were in very bad category with certainty level of 0-38% which is unsuitable for drinking purposes; samples in bad category had certainty level that ranged from 38 to 50%; samples in medium to good category had certainty levels from 50 to 100%, and the remaining samples were in good to excellent category, suitable for drinking purposes, with certainty levels from 63 to 100%.