Ferrocene-quinoxaline Y-shaped chromophores as fascinating second-order NLO building blocks for long lasting highly active SHG polymeric films

The first example of a Y-shaped ferrocene quinoxaline derivative with a surprisingly high and stable second harmonic generation (SHG) response in composite polymeric films is reported. The interesting quadratic hyperpolarizability values of different substituted Y-shaped chromophores are also investigated in solution by the EFISH technique

Interaction of chemical contaminants with microplastics: Principles and perspectives

Scientific evidences abound of the occurrence of plastic pollution, from mega- to nano-sized plastics, in virtually all matrixes of the environment. Apart from the direct effects of plastics and microplastics pollution such as entanglement, inflammation of cells and gut blockage due to ingestion, plastics are also able to act as vectors of various chemical contaminants in the aquatic environment. This paper provides a review of the association of plastic additives with environmental microplastics, how the structure and composition of polymers influence sorption capacities and highlights some of the models that have been employed to interpret experimental data from recent sorption studies. The factors that influence the sorption of chemical contaminants such as the degree of crystallinity, surfaceweathering, and chemical properties of contaminants. and the implications of chemical sorption by plastics for the marine food web and human health are also discussed. It was however observed that most studies relied on pristine or artificially aged plastics rather than field plastic samples for studies on chemical sorption by plastics

Low frequency 1/f noise in doped manganite grain-boundary junctions

We have performed a systematic analysis of the low frequency 1/f-noise in single grain boundary junctions in the colossal magnetoresistance material La_{2/3}Ca_{1/3}MnO_{3-delta}. The grain boundary junctions were formed in epitaxial La_{2/3}Ca_{1/3}MnO_{3-delta} films deposited on SrTiO_3 bicrystal substrates and show a large tunneling magnetoresistance of up to 300% at 4.2 K as well as ideal, rectangular shaped resistance versus applied magnetic field curves. Below the Curie temperature T_C the measured 1/f noise is dominated by the grain boundary. The dependence of the noise on bias current, temperature and applied magnetic field gives clear evidence that the large amount of low frequency noise is caused by localized sites with fluctuating magnetic moments in a heavily disordered grain boundary region. At 4.2 K additional temporally unstable Lorentzian components show up in the noise spectra that are most likely caused by fluctuating clusters of interacting magnetic moments. Noise due to fluctuating domains in the junction electrodes is found to play no significant role.Comment: 9 pages, 7 figure

Economic implications of groundwater exploitation in hard rock areas of southern peninsular India

The present paper analyses the consequences of groundwater exploitation by using field-level data collected from two distinct well irrigated areas of Karnataka. The study results show that the consequences arising out of groundwater overexploitation are severe in high well interference area compared to low well interference area. The burden of well failure is more or less equally shared by all categories of farmers but small farmers are the worst victims of resource scarcity. As a result, overexploitation of groundwater has different impacts on different categories of farmers in terms of access to groundwater, cost and returns to groundwater irrigation and its negative externality cost. The study suggests maintaining inter-well distance to prevent resource mining and calls for supply and demand side interventions. The institutional reform is necessary to restore surface water bodies to facilitate aquifer recharge

Synthesis and spectral characterization of diorganodiaminosilanes [(ArNH)(2)SiPhMe] (Ar=2,6-(Pr2C6H3)-Pr-i; 2,4,6-Me3C6H2) and lithium silylamide [(2,6-Et2C6H3NLi)(2,6-Et2C6H3NH)SiPh2]

Aminosilanes bearing bulky substituents on nitrogen centers, [(ArNH)(2)SiPhMe] (Ar = 2,6-(Pr2C6H3)-Pr-i (1), 2,4,6-Me3C6H2 (2)) and half-sandwich lithium silylamide [(2,6-Et2C6H3NLi)(2,6-Et2C6H3NH)SiPh2] (3) have been prepared and characterized by elemental analysis, IR, EI mass and NMR (H-1 and Si-29) spectroscopic studies. The solid state structures of 2 and 3 have been determined by single crystal X-ray diffraction studies. The molecule 2 has a C-1 symmetry due to the steric crowding, and the two N-H protons are approximately trans to each other. The amido nitrogen atoms in 2 show significant deviation from trigonal-planar geometry, and as a result, the observed Si-N bonds are marginally longer than those observed in aminosilanes with planar nitrogen atoms. The molecule 3 exists as discrete dimer with an inversion center. The Li ion in 3 forms intramolecular pi-complex with the neighboring aryl (2,6-Et2C6H3) group, to form a half-sandwich lithium silylamide. (c) 200

Synthesis, spectral characterization, and single crystal X-ray structures of a series of manganese-2,2 '-bipyridine complexes derived from substituted aromatic carboxylic acids

Reaction of [Mn(2,2'-bpy)(2)(OAc)](ClO(4))(H(2)O) with a series of aromatic carboxylic acids yields new Mn(II)carboxylates [Mn(2,2'-bpy)(2)(L)](ClO(4))}(2) (1-3), [Mn(2,2'-bpy)(2)(L)(2)] (4-5) and [Mn(2,2'-bpy)(2)(L)(-H(2)O)]( ClO(4)) (6) (L = 2-aminobenzoate (2-aba) (1), 4-hydroxybenzoate (4-hba) (2), thiophene-2-carboxylate (2-tca) (3), 2-hydroxynapthoate (2-hnapa) (4), 3,5-diisopropylsalicylic acid (dipsa) (5), 2,4, 6-triisopropylbenzoate (tipba) (6)). The new compounds have been characterized with the aid of elemental analysis, spectroscopy, and single-crystal X-ray diffraction studies. Compounds 1-3, which have been synthesized from less bulky carboxylic acids, are dimeric in the solid-state. Compounds 4-6, which are derived from more bulkier aromaric carboxylic acids, exist as monomeric complexes. In the case of 6, where very bulky 2,4,6-triisopropyl benzoic acid is used as the starting material, only one carboxylate ligand binds to the metal, resulting in a cationic complex. Interestingly in all the six complexes, the C-H hydrogen atoms of the 2,2'-bpy ligands are involved in extensive hydrogen bonding with the carboxylate oxygen atoms of the adjacent molecules and hence form non-covalent 1-D or 2-D aggregates in the solid state. (C) 2010 Elsevier B.V. All rights reserved

Synthesis, characterization and structures of diphenyldiaminosilanes bearing bulky substituents on nitrogen

Aminosilanes bearing bulky substituents on nitrogen centers, [(ArNH)(2)SiPh2] (Ar = 2,6-(Pr2C6H3)-Pr-i (1), 2,4,6-Me3C6H2 (2), 2,6-Et2C6H3 (3)), have been prepared in good yields by the addition of dichlorodiphenylsilane to the corresponding substituted monolithiated aniline. The new compounds have been characterized by elemental analysis and IR, El mass and NMR (H-1 and Si-29) spectroscopic studies. The solid-state structures of I and 3 have been determined by single crystal X-ray diffraction studies. The molecules have a C-s symmetry and the two N-H protons are approximately trans to each other. The amido nitrogen atoms show significant deviation from trigonal-planar geometry, as a result of which the observed Si-N bonds are marginally longer than those observed in aminosilanes with planar nitrogen atoms. (C) 2003

Analysis of economic incentives for managing risk at the farm level in the context of climate change

Weather indexed crop insurance has the potential of offering risk management to high-risk populations in poor areas, by lowering transaction costs of managing contracts and payouts, thereby offering affordable insurance even to poor farmers. Lower transaction costs relative to multiperil yield-based insurance, can be achieved through use of local weather data, rather than on-farm crop cutting experiments, that lowers verification costs, while maintaining, or even lowering basic risk

Vulnerability assessment, impacts of climate change on agricultural production in the Godavari River Basin, India.

In Nagothu, U. S.; Gosain, A. K.; Palanisami, Kuppannan (Eds.). Water and climate change: an integrated approach to address adaptation challenges. New Delhi, India: Macmilla