Selective Curcuminoid Separation and Detection via Nickel Complexation and Adsorptive Stripping Voltammetry

Curcumin is a widely studied biologically active redox molecule. Although sensitive, electrochemical methods are commonly hindered by their lack of specificity. This article demonstrates how curcumin may be readily separated from other structurally and electrochemically similar redox moieties. This separation is achieved through exploitation of the molecules diketone functionality providing a route for its selective chelation to nickel(II). Recovery of the curcumin from the nickel complex is achieved simply and quantitatively through acidification of the precipitate. Adsorptive stripping voltammetry at a carbon screen‐printed electrode (SPE) is utilised both as a method for evidencing the effectiveness of the separation technique but further as a procedure for the analytical quantification of the curcumin concentration.     

Evolved Algorithm and Vibration Stability for Nonlinear Disturbed Security Systems

In this paper, a method sustaining system stability after decomposition is proposed. Based on the stability criterion derived from the energy function, a set of intelligent controllers is synthesized which is used to maintain the stability of the system. The sustainable stability problem can be reformulated as a Linear Matrix Inequalities (LMI) problem. The key to guaranteeing the stability of the system as a whole is to find a common symmetrically positive definite matrix for all subsystems. Furthermore, the Evolved Bat Algorithm (EBA) is employed to replace the pole assignment method and the conventional mathematical methods for solving the LMI. The EBA is utilized to find feasible solutions in terms of the energy equation. The experimental results show that the EBA is capable of providing proper solutions, which satisfy the sustainability and stability criteria, after a short period of recursive computing.     

Exact scalar field cosmologies in a higher derivative theory

We obtain exact cosmological solutions of a higher derivative theory described by the Lagrangian L=R+2αR ² in the presence of interacting scalar field. The interacting scalar field potential required for a known evolution of the FRW universe in the framework of the theory is obtained using a technique different from the usual approach to solve the Einstein field equations. We follow here a technique to determine potential similar to that used by Ellis and Madsen in Einstein gravity. Some new and interesting potentials are noted in the presence of R ² term in the Einstein action for the known behaviours of the universe. These potentials in general do not obey the slow rollover approximation.     

Low-lying quasiparticle states and hidden collective charge instabilities in parent cobaltate superconductors

We report a state-of-the-art photoemission (angle-resolved photoemission spectroscopy) study of high quality single crystals of NaxCoO2 the series focusing on the fine details of the low-energy states. The Fermi velocity is found to be small (<0.5 eV A) and only weakly anisotropic over the Fermi surface at all dopings, setting the size of the pair wave function to be on the order of 10-20 nm. In the low-doping regime, the exchange interlayer splitting vanishes and two-dimensional collective instabilities such as 120 degrees -type fluctuations become kinematically allowed. Our results suggest that the unusually small Fermi velocity and the unique symmetry of kinematic instabilities distinguish cobaltates from most other oxide superconductors.     

Allyldifluorophosphite-metal chemistry: Ru complexes of F2POC3H5 and the crystal structure of (Ph3P)2(F2POC3H5)Ru(CO)(Cl)H

With several chloro ruthenium phosphine complexes, allyldifluorophosphite, F₂POC₃H₅, displaces triphenylphosphine to form new compounds in which it acts as a phosphorus donor ligand. The new complexes [PPh₃]₂[F₂POC₃H₅]Ru[CO][Cl][H], I, and [(PPh₃)₂(F₂POC₃H₅)₂RuCl₂]_nII, hav characterized by chemical, spectroscopic, and, in the case of I, crystallographic means. This behaviour of F₂POC₃H₅ contrasts to its reactions with several platinum and palladium chloro complexes where it undergoes Arbuzov-type rearrangements.     

Halogenated secondary metabolites from Laurencia obtusa

A new sesquiterpene (1), and a halogenated C15 acetogenin (2), a stereoisomer of neoisoprelaurefucin were isolated from Laurencia obtusa. Four known compounds laurencienyne (3), rogiolenyne B (4), obtusenol (5), and (3E)-dactomelyne (6) were also isolated from this alga. Rogiolenyne B (4) and (3E)-dactomelyne (6) were found for the first from this species. The structures of these compounds were elucidated by spectroscopic methods. The unambiguous assignments of the 1H and 13C NMR spectral data of (5) and 13C NMR data of (6) were also reported for the first time.     

The direct solution of the radiative transfer equation for optically thick atmospheres

A simple improvement of a previous direct method of solution of the spherical harmonics approximation to the radiative transfer equation results in higher computational efficiencies by factors of 2–4; these higher efficiencies are particularly important to shorten the lengthy computations required in optically thick nonhomogeneous atmospheres.     

Comments on spin effects in proton-proton cross section measurements

Bounds are obtained from positivity on the possible size of spin dependent effects on the proton-proton total cross-section.     

Loops on loops: generation of complex scaffolded peptides presenting multiple cyclic fragments

Scaffolded peptides presenting two different cyclic peptide fragments through a cyclic peptidomimetic scaffold in a site-selective fashion, were generated by stepwise solid phase synthesis and fragment condensation in parallel, demonstrating that either strategy is adequate to generate complex scaffolded peptides.