Heteronuclear dipolar decoupling is an essential requirement for extracting structural information from the (13)C NMR spectra of liquid crystals. Efficient schemes for heteronuclear dipolar decoupling in such systems are formulated here by supercycling SW(f)-TPPM, a sequence introduced recently for this purpose in rotating solids. These sequences are compared with two other commonly used decoupling schemes in liquid-crystal NMR, SPINAL-64 and SW(f)-TPPM, by analyzing the intensities of various resonances in the proton decoupled (13)C spectrum of the liquid-crystal 4-n-pentyl-4'-cyanobiphenyl (5CB). The effectiveness of the decoupling programs with respect to experimental parameters such as RF field strength, decoupler offset frequency and phase angle is also presented.

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Effective inhibition of metallic corrosion to prevent its consequent loss is one of the serious apprehensions for industries in the modern world. This paper analyses the application of poly(2-ethyl-2-oxazoline) (PEOX) as an effective inhibitor of corrosion, when it is made to be in contact with the surfaces of mild steel (MS). The sustainability of MS against corrosion in 0.1 M Hydrochloric acid solution in the presence of known concentration of PEOX is assessed by potentiodynamic polarization (PDP) measurements, linear polarization studies (LPR), and electrochemical impedance spectroscopy (EIS). It was observed that PEOX behaves as better inhibitor for mild steel corrosion in 0.1 M HCl solution and it show enhanced inhibition efficiency (IE%) 79% at a concentration of 50 ppm. The polarization experiments indicated that addition of PEOX in concentrations varies from 25 ppm to 50 ppm induces a decrease of both cathodic and anodic currents densities. Also, the micrographs recorded by the Scanning Electron Microscopy confirm that molecules of PEOX act as corrosion inhibitors for the surfaces of MS in 0.1 M HCl. The stability of the MS surface in a corrosion-prone environment is traced by measuring the contact angles of water droplets placed on the MS surface, to quantify the extent of deterioration, if any, due to corrosion. The results presented here show that the compound PEOX performs as a mixed-type inhibitor against corrosion at the MS surface in acidic medium. Theoretical studies based on the electronic structure of PEOX in aqueous medium also support its performance as a successful corrosion-inhibitor.

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Indigenous chemical compounds found in plants such as phenolics, alkaloids, carotenoids, xanthophylls and terpenoids are used by chemists for a variety of synthetic applications. The Sustainable Chemistry or green chemistry,...

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The biodiversity in aquatic systems are indirectly controlled by their nutrient dynamics. The abundance of phytoplanktons and zooplanktons depends on the availability of nutrients such as nitrates, phosphates and silicates since these are the building blocks for their further growth. The phytoplanktons act as prey for the next higher trophic level including various fishes and other small organisms. One of the factors that enchant the migratory birds at some particular locations is the availability of the species of organisms that they prey on. In this paper a preliminary analysis is done to explore the nutrient dynamics of selected tropical aquatic systems in order to correlate the arrival of migratory birds at those locations. Water samples are collected from coastal region of Aleppey, Purakkad and Koonthankulam Bird Sancturay. The latter two sites are the important destination of many migratory water birds including Pallus Gull, Heuglins Gull, Bar-headed goose, Comb Duck and Spot Billed Pelican. The samples are analyzed chemically to trace the nutrient compositions and the related chemical parameters such as temperature, pH, conductivity, primary productivity, chloride, salinity, turbidity, nitrate, phosphate, dissolved oxygen and biochemical oxygen demand. Remarkable differences are observed mainly in the composition of phosphate, organic matter content and salinity. Finally, an attempt has been done to correlate the biodiversity of these locations with the chemical parameters and the prevailing nutrient compositions.