Can Co(II) or Cd(II) substitute for Zn(II) in zinc fingers?

Zinc finger domains consist of sequences of amino acids containing cysteine and histidine residues tetrahedrally coordinated to a zinc ion. The role of zinc in a DNA binding finger was considered purely structural due to the absence of redox chemistry in zinc. However, whether other metals e.g. Co(II) or Cd(II) can substitute Zn(II) is not settled. For an answer the detailed interaction of Co(II) and Cd(II) with cysteine methylester and histidine methylester has been investigated as a model for the zinc core in zinc fingers. The study was extended to different temperatures to evaluate the thermodynamic parameters associated with these interactions. The results suggest that zinc has a unique role.     

Grafting of Vinyl Monomers onto Nylon

Polymer chemists have been successful in applying polymerization techniques to develop copolymers of natural and synthetic macromolecules [l]. The literature abounds with examples of the successful formation of copolymers from natural and synthetic macromolecules [2–5]. Copolymerization is attractive to chemists as a means of modifying macromolecules since, in general, degradation can be minimized. Despite the heterogeneity and complexity of these copolymers, much has been achieved in their characterization. The desirable properties of the polymer are retained and additional properties are acquired through the added polymer. The desired material may be formed in situ by polymerization of a monomer or monomers, by condensation of reactants, or by the decomposition of a preformed polymer.     

Modelling of multifrequency IRMPD for laser isotope separation

The process of infrared multiple photon dissociation (IRMPD) of molecules is of great fundamental importance and has practical significance, such as isotope separation etc. Unfortunately, a clear insight into the process has been hindered by the bewildering array of important variables affecting MPD. The dissociation probability γ (φ) i.e. the yield has been found to be a sensitive function of laser fluence φ along with numerous other parameters like laser frequency, gas pressure etc. We have shown that in single frequency IRMPD, an accurate quantitative characterization of the dissociation probability can be adequately expressed by a ‘power law’ model with two fitting parameters namely critical fluence, φ_c and multiphoton order,m. This model was exploited in analysing our MPD results on various systems. However, the small isotope shift encountered in heavy elements and the sticking phenomenon observed in small light molecules restrict respectively the separation factor and the dissociation yield. These problems can effectively be tackled by irradiation with multifrequency laser beams which can be chosen appropriately on the basis of spectroscopic features. Based on our success in single frequency model, multifrequency IRMPD is modelled by a functional form containing the product of power law terms for individual fluences on irradiation frequencies. This model is successfully benchmarked with our experimental results on multifrequency LIS of tritium. Such knowledge can be utilized for appropriate separation process design, evaluation and optimization.     

Characterisation of different polymorphs of tris(8-hydroxyquinolinato)aluminium(III) using solid-state NMR and DFT calculations

Background  

Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq₃, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq₃ in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies.     

Slope parameter and scaling of differential cross-section of Λ-p scattering

The claim of Mohapatra and Maharana thattb(s) is a better scaling variable thant(lns)² is put to test in the case of Λ-p scattering, after parametrizingb(s) asC ₁ +C ₂(lns)α. It was observed that in this case the data also prefer anα value which is close to those obtained by Mohapatra and Maharana for other scattering processes.     

Synthesis and Luminescence of Ba2ScCl7

Physics of the Solid State - New results on luminescence in Ba2ScCl7 are reported. Lanthanides Eu2+ and Ce3+ were chosen as activators. The phosphors could be prepared by a simple wet chemical...     

Polyaromatic heterocycles through intramolecular alkyne carbonyl metathesis: 5-Acylnaphtho[2,1-b]benzofurans

A modular approach to 5-acylated naphtho[2,1-b]benzofurans was developed where Sonogashira cross-coupling and intramolecular alkyne carbonyl metathesis were sequentially employed to build the aromatic benzene C ring of naphtho[2,1-b]benzofuran with an acyl group at the C5 position.     

A simple and rapid method for determination of boron in fast breeder reactor components

The present paper describes a new analytical method developed for direct determination of boron in steels using radio frequency glow discharge optical emission spectrometer. “Single parameter alternative method” technique has been used to optimize the various experimental conditions of glow discharge plasma such as forward power, gas pressure inside plasma chamber, pre-integration time, and integration time. Different emission lines for boron were studied and inter element interference effect is also discussed in the paper. A complete statistical analysis has been done to validate the developed method. A RSD of less than ±5% is achieved for boron in the range of 0.0010–0.020% in Steels using this method.     

Determination of molybdenum(VI) by differential pulse polarographic technique using 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D)

A novel analytical reagent 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D) was synthesized for the determination of molybdenum(VI). The present paper reveals the detailed study of electroanalytical behaviour for [Mo-(4-2-HPEDB-1,3,D)] complex under optimized conditions. The peak obtained for [Mo-(4-2-HPEDB-1,3,D)] prevent the interference of foreign ions which shows the sensitivity of the proposed method. The linearity was maintained at the concentration range of 0.5–200 μg/mL at pH 4.5 with correlation factor 0.9997. The present method was successfully applied for the analysis of molybdenum(VI) in biological fluids and plant material. The results obtained from the proposed method show good agreement with reference method.     

Spin-polarized electron–electron quantum bilayers: Finite width effect

We study the effect of finite width on the ground-state of a spin-polarized electron–electron quantum bilayers (EEBL) system at temperature T=0. Correlations among carriers are treated beyond the static mean-field theories by using the quantum or dynamical version of Singwi, Tosi, Land and Sjölander (qSTLS) theory. Numerical results are presented for the pair-correlation function, the ground-state energy, the static density susceptibility, and the static local-field correction factor as a function of density parameter r_sl and interlayer spacing d. Interestingly, we find that the inclusion of finite width lowered the critical density, for the onset of Wigner crystal (WC) ground-state, as compared to the similar recent study of spin-polarized EEBL system without finite width effect. Further, spin-polarization effect is seen to introduce a marked change in the ground-state energy of the EEBL system as compared to the results of unpolarized EEBL system with finite width. Results of ground-state energies are also compared with the recent diffusion Monte Carlo (DMC) and variational Monte Carlo (VMC) simulation studies of spin-polarized EEBL system with zero width.