Agriculture and food sovereignty : challenges and opportunities in North East India

“This report is an output from a two day workshop that brought together farmers and peasant groups, fish worker unions, academics and researchers to discuss the existing trends and problems in agriculture from states of Assam, Manipur, Meghalaya, Mizoram, Arunachal Pradesh, Nagaland and Tripura. The report highlights issues such as plantation economy, upland agriculture, impact of trade policies on agriculture and fisheries.

Binding Constant Measurement by Hyper-Rayleigh Scattering: Bilirubin-Human Serum Albumin Binding as a Case Study

In this paper, a new application of the hyper-Rayleigh scattering technique in determining multiple binding constants of a small molecule like bilirubin to a macromolecule like the protein human serum albumin has been demonstrated. Human serum albumin has two binding sites for bilirubin, and the binding constants have been measured by carrying out a second harmonic titration of the protein against bilirubin and vice versa. The measured binding constants K_1 = 1.5 \pm 0.43 \times 10^7 M^-^1 and K_2 = 1.01 \pm 0.16 \times 10^6 M^-^1 agree well with the reported values obtained by other methods

Binding constant measurement by hyper-Rayleigh scattering: bilirubin-human serum albumin binding as a case study

In this paper, a new application of the hyper-Rayleigh scattering technique in determining multiple binding constants of a small molecule like bilirubin to a macromolecule like the protein human serum albumin has been demonstrated. Human serum albumin has two binding sites for bilirubin, and the binding constants have been measured by carrying out a second harmonic titration of the protein against bilirubin and vice versa. The measured binding constants K<SUB>1</SUB> = 1.5 &#177; 0.43 &#215; 10<SUP>7</SUP> M<SUP>-1</SUP> and K<SUB>2</SUB> = 1.01 &#177; 0.16 &#215; 10<SUP>6</SUP> M<SUP>-1</SUP> agree well with the reported values obtained by other methods

First hyperpolarizability of bacteriorhodopsin, retinal and related molecules revisited

The previously reported beta values of BR and retinal based chromophores were very high but subsequent measurements found them to be much less. We have found that the beta values of these compounds do not vary so much with experimental conditions as with the method of analysis. Hyper-Rayleigh scattering measurements at 1543 and 1907 nm produce more realistic beta values close to the intrinsic (static) hyperpolarizability, beta(0) which for BR is still very high (275 x 10 (30) esu). The optical nonlinearity of BR arises entirely due to the protonated retinal Schiff Base (PRSB) which in its isolated form has the same intrinsic hyperpolarizability as that of the rotein

Estimation of electron temperature in 14.45 GHz ECR ion source plasma by analysis of Bremsstrahlung spectra

965-968Electron Cyclotron Resonance Ion Sources (ECRIS) are known to produce intense X-rays of the order of 100’s of keV. Energy of electrons in the resonantly heated microwave plasma has been estimated by analyzing the Bremsstrahlung spectra obtained using a standard alkali halide (NaI [Ti]) crystal detector. Experiments were carried out on argon plasma discharge from high performance ECR ion source operating at 14.45 GHz. The dependency of X-ray emission with microwave power has been studied in the range 50-400 W. It is verified that maximum energy gained by electrons in ECR plasma follows a power law Emax ⍺ P³/⁸. X-rays of more than 800 keV energy can be generated at very low microwave power as 400 W. The influence of magnetic field and gas pressure in the production of X-rays has also been analyzed

The effect of halogen atom on the molecular quadratic nonlinearity of half sandwich complexes in the presence of an acceptor

Half sandwich complexes of the type [CpM(CO)(n)X] {X=Cl, Br, I; If, M=Fe, Ru; n=2 and if M=Mo; n=3} and [CpNiPPh3X] {X=Cl, Br, I} have been synthesized and their second order molecular nonlinearity (beta) measured at 1064 nm in CHCl3 by the hyper-Rayleigh scattering technique. Iron complexes consistently display larger beta values than ruthenium complexes while nickel complexes have marginally larger beta values than iron complexes. In the presence of an acceptor ligand such as CO or PPh3, the role of the halogen atom is that of a pi donor. The better overlap of Cl orbitals with Fe and Ni metal centres make Cl a better pi donor than Br or I in the respective complexes. Consequently, M-pi interaction is stronger in Fe/Ni-Cl complexes. The value of beta decreases as one goes down the halogen group. For the complexes of 4d metal ions where the metal-ligand distance is larger, the influence of pi orbital overlap appears to be less important, resulting in moderate changes in beta as a function of halogen substitution. (C) 2006 Elsevier B.V. All rights reserved

The effect of halogen atom on the molecular quadratic nonlinearity of half sandwich complexes in the presence of an acceptor

Half sandwich complexes of the type [CpM(CO)<SUB>n</SUB>X] {X = Cl, Br, I; If, M = Fe, Ru; n = 2 and if M = Mo; n = 3} and [CpNiPPh<SUB>3</SUB>X] {X = Cl, Br, I} have been synthesized and their second order molecular nonlinearity (β) measured at 1064 nm in CHCl<SUB>3</SUB> by the hyper-Rayleigh scattering technique. Iron complexes consistently display larger β values than ruthenium complexes while nickel complexes have marginally larger β values than iron complexes. In the presence of an acceptor ligand such as CO or PPh<SUB>3</SUB>, the role of the halogen atom is that of a π donor. The better overlap of Cl orbitals with Fe and Ni metal centres make Cl a better p donor than Br or I in the respective complexes. Consequently, M-π interaction is stronger in Fe/Ni-Cl complexes. The value of β decreases as one goes down the halogen group. For the complexes of 4d metal ions where the metal-ligand distance is larger, the influence of π orbital overlap appears to be less important, resulting in moderate changes in β as a function of halogen substitution

Optically transparent and thermally stable nonlinear optic chromophores featuring a thieno[2,3-b]thiophene donor

A thieno[2,3-b]thiophene core has been utilized as a \pi-donor component to design two series of push–pull thienothiophenes by introducing various acceptor groups either via olefinic or aza-spacers. The molecules show a UV–visible cut-off wavelength below the second harmonic generation (SHG) at $\lambda /2$ of 532 nm, thereby conforming to the nonlinearity–transparency trade-off. Second order molecular nonlinearity, \beta measured by Hyper-Rayleigh scattering technique was found in the range of $9.58–47.66 X 10^{-30} esu$, while the Kurtz powder technique produced signals of the order of 0.43–1.02 U. Thermal decomposition temperatures measured by differential scanning calorimetry revealed decomposition temperatures \geq 275° C, indicating high thermal stability