Comparative study of nucleation and growth mechanism of cobalt electrodeposited on ITO substrate in nitrate and chloride electrolytes

Journal of Solid State Electrochemistry - A comparative study of the electrochemical deposition of cobalt on tin-doped indium oxide (ITO) substrate was carried out using electrochemical techniques...     

Radar scatter cross sections for two-dimensional random rough surfaces – full wave solutions and comparisons with experiments

Abstract

In this paper, the full wave expressions for the radar scattering cross sections for two-dimensional random rough surfaces are obtained. The rough-surface height/slope correlations are accounted for in this analysis. Analytical and numerical comparisons of the full wave solution with the small perturbation and physical optics solutions are made for isotropic, homogeneous random rough surfaces with Gaussian probability density function. The full wave results are also compared with experimental results.     

Synthesis of enantiopure homo and copolymers by raft polymerization and investigation of their enantioselective lipase‐catalyzed esterification

Homo and copolymers were synthesized from enantionpure (R)‐ and (S)‐1‐(4‐vinylphenyl)ethanol by reversible addition‐fragmentation chain transfer polymerization. The polymerization conditions were optimized resulting in dioxane as the preferred reaction solvent. First‐order polymerization kinetics and well‐defined enantiopure homopolymers with low dispersities were obtained. In agreement with their enantiomeric composition, the (R) and (S)‐polymers gave opposite optical rotation of light. Polymer analogous esterification of the chiral hydroxy groups catalyzed by enantioselective Candida antarctica Lipase B was strongly (R)‐selective. Esterification on the homopolymer and copolymers could be achieved to a maximum of around 50 %. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Domain swapping proceeds via complete unfolding: a 19F- and 1H-NMR study of the Cyanovirin-N protein

Domain swapping creates protein oligomers by exchange of structural units between identical monomers. At present, no unifying molecular mechanism of domain swapping has emerged. Here we used the protein Cyanovirin-N (CV-N) and (19)F-NMR to investigate the process of domain swapping. CV-N is an HIV inactivating protein that can exist as a monomer or a domain-swapped dimer. We measured thermodynamic and kinetic parameters of the conversion process and determined the size of the energy barrier between the two species. The barrier is very large and of similar magnitude to that for equilibrium unfolding of the protein. Therefore, for CV-N, overall unfolding of the polypeptide is required for domain swapping.     

Druggability Assessment of Allosteric Proteins by Dynamics Simulations in the Presence of Probe Molecules

Druggability assessment of a target protein has emerged in recent years as an important concept in hit-to-lead optimization. A reliable and physically relevant measure of druggability would allow informed decisions on the risk of investing in a particular target. Here, we define "druggability" as a quantitative estimate of binding sites and affinities for a potential drug acting on a specific protein target. In the present study, we describe a new methodology that successfully predicts the druggability and maximal binding affinity for a series of challenging targets, including those that function through allosteric mechanisms. Two distinguishing features of the methodology are (i) simulation of the binding dynamics of a diversity of probe molecules selected on the basis of an analysis of approved drugs and (ii) identification of druggable sites and estimation of corresponding binding affinities on the basis of an evaluation of the geometry and energetics of bound probe clusters. The use of the methodology for a variety of targets such as murine double mutant-2, protein tyrosine phosphatase 1B (PTP1B), lymphocyte function-associated antigen 1, vertebrate kinesin-5 (Eg5), and p38 mitogen-activated protein kinase provides examples for which the method correctly captures the location and binding affinities of known drugs. It also provides insights into novel druggable sites and the target's structural changes that would accommodate, if not promote and stabilize, drug binding. Notably, the ability to identify high affinity spots even in challenging cases such as PTP1B or Eg5 shows promise as a rational tool for assessing the druggability of protein targets and identifying allosteric or novel sites for drug binding.     

Reaction‐Based Colorimetric and Ratiometric Fluorescence Sensor for Detection of Cyanide in Aqueous Media

A stilbene‐based compound ( 1 ) has been prepared and was highly selective for the detection of cyanide anion in aqueous media even in the presence of other anions, such as F^?, Cl^?, Br^?, I^?, ClO₄^?, H₂PO₄^?, HSO₄^?, NO₃^?, and CH₃CO₂^?. A noticeable change in the color of the solution, along with a prominent fluorescence enhancement, was observed upon the addition of cyanide. The color change was observed upon the nucleophilic addition of the cyanide anion to the electron‐deficient cyanoacrylate group of 1 . The spectral changes induced by the reaction were analyzed by comparison with two model compounds, such as compound 2 with dimethyl substituents and compound 3 without a cyanoacrylate group. An intramolecular charge‐transfer (ICT) mechanism played a key role in the sensing properties, and the mechanism was supported by DFT/TDDFT calculations.     

Approximate Solutions to the Dirac Equation with Effective Mass for the Manning–Rosen Potential in N Dimensions

The solutions of the effective mass Dirac equation for the Manning–Rosen potential with the centrifugal term are studied approximately in N dimension. The relativistic energy spectrum and two-component spinor eigenfunctions are obtained by the asymptotic iteration method. We have also investigated eigenvalues of the effective mass Dirac–Manning–Rosen problem for α = 0  or  α = 1. In this case, the Manning–Rosen potential reduces to the Hulthen potential.     

Two bit all-optical analog-to-digital converter based on nonlinear Kerr effect in 2D photonic crystals

We have demonstrated the performance of a novel design for a single wavelength 2-bit all-optical analog-to-digital converter (ADC). This converter consists of two high efficient channel drop filters with a coupled cavity-based wavelength selective reflector in a 2D photonic crystal with total length of 15.87 μm. The A/D conversion is achieved by using nonlinear Kerr effect in the cavities. The output ports switch to state ‘1’ at different input power levels to generate unique states preferred for an ADC. This conversion is simulated by the finite difference time domain (FDTD) method for 5 different power levels. The proposed structure can function as a two-bit ADC with a 60 mW/μm input pulse and its maximum sampling rate is found to be ~ 45 GS/s.     

Spin-dependent resonant tunneling in ZnSe/ZnMnSe heterostructures

Using the transfer matrix method and the effective-mass approximation, the effect of resonant states on spin transport is studied in ZnSe/ZnMnSe/ZnSe/ZnMnSe/ZnSe structures under the influence of both electric and magnetic fields. The numerical results show that the ZnMnSe layers, which act as spin filters, polarize the electric currents. Variation of thickness of the central ZnSe layer shifts the resonant levels and exhibits an oscillatory behavior in spin current densities. It is also shown that the spin polarization of the tunneling current in geometrical asymmetry of the heterostructure where two ZnMnSe layers have different Mn concentrations, depends strongly on the thickness and the applied bias.