Synthesis and bioefficacy evaluation of new 3-substituted-3,4-dihydro-1,3-benzoxazines

A new series of 1, 3-Benzoxazines were synthesized, characterized (¹H NMR and ¹³C NMR) and evaluated for their pesticidal activity. Six new 3-alkyl-3, 4-dihydro-4-methyl-2H-1, 3-benzoxazines (1-6) were prepared by hydroxymethylation of secondary amines with formaldehyde in 65–68% yields. These compounds were screened for there IGR activity against Spodoptera litura and for antifungal fungal activity in vitro against Sclerotium rolfsii ITCC 6181 by poisoned food technique. Insect Growth Regulatory (IGR) activity against Spodoptera litura showed that compound 3-Nonyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines was most effective as IGR with larval GI₅₀ of 1.863 μ g/Insect. Compounds 3-Octyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines and 3-Decyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines were effective IGRs. Antifungal screening revealed that compound 3-Dodecyl-3, 4-dihydro-4-methyl-2H-1,3-benzoxazines, was highly effective against Sclerotium rolfsii with LC₅₀ value 31.7 mg L^?1 comparable with commercial fungicide Hexaconazole (LC₅₀ 1.27 mg L^?1). Also compounds 3-Nonyl-3, 4-dihydro-4-methyl-2H-1,3-benzoxazines and 3-Decyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines displayed promising fungitoxicity. The results described in this paper are promising and provides new array of synthetic chemicals to be utilized as pesticides.     

Atmospheric deposition studies of heavy metals in Arctic by comparative analysis of lichens and cryoconite

Lichens and cryoconite (rounded or granular, brownish-black debris occurring in holes on the glacier surface) from Ny-Ålesund were used for understanding the elemental deposition pattern in the area. Lichen samples collected from low-lying coastal region and cryoconite samples from high altitudinal glacier area were processed and analysed for elements such as aluminium (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) through inductively coupled plasma mass spectrometry. Results showed that heavy metals, Al and Fe, are present in high concentration in the cryoconite samples. Al was also present in high amounts in seven of the eight lichen samples studied. The general scheme of elements in the decreasing order of their concentrations for most of the cryoconite samples was Al?>?Fe?>?Mn?>?Zn?>?V?>?Pb?>?Cr?>?Ni?>?Cu?>?Co?>?As?>?Cs?>?Cd while that for the lichen samples was Al?>?Fe?>?Zn?>?Mn?>?Pb?>?Cu?>?Cs?>?Cr?>?Ni?>?V?>?Co?>?As?>?Cd. Similarity in trends in the two sample types confirms that the environment indeed contains these elements in that order of concentration which overtime got accumulated in the samples. Overall comparison showed most elements to be present in high concentrations in the cryoconite samples as compared to the lichen samples. Within the lichens, elemental accumulation data suggests that the low-lying site (L-2) from where Cladonia mediterranea sample was collected was the most polluted accumulating a number of elements at high concentrations. The probable reasons for such deposition patterns in the region could be natural (crustal contribution and sea salt spray) and anthropogenic (local and long-distance transmission of dust particles). In the future, this data can form a baseline for monitoring quantum of atmospheric heavy metal deposition in lichens and cryoconite of Svalbard, Arctic.     

A design chart for estimation of horizontal displacement in municipal landfills

This paper describes the development of a design chart for the estimation of maximum horizontal displacement within a municipal landfill using the height and the side slope of the landfill. The design chart is based on the results of a finite element parametric study in which the behaviour of the municipal solid waste (MSW) was modeled using a non-linear elastic hyperbolic model. The model input parameters, i.e. non-linear stiffness, shear strength and unit weight of MSW, were obtained from laboratory testing data and an extensive stochastic numerical modelling exercise. Non-linear variations of unit weight as well as Young’s modulus of MSW with depth were incorporated in the finite element analyses. The validity of the design chart was assessed using field monitoring results from a large landfill located in Ontario, Canada.