Gamma-ray spectroscopy with relativistic exotic heavy-ions

Feasibility of gamma-ray spectroscopy at relativistic energies with exotic heavy-ions and new generation of germanium detectors (segmented Clover) is discussed. An experiment with such detector array and radioactive is discussed.     

A gamma-ray detector for capillary zone electrophoresis and its use in the analysis of some radiopharmaceuticals

The construction and evaluation of a gamma-ray detector for capillary zone electrophoresis is described. The detector was shown to have a linear response from the limit of detection 10 to 500 Bqcm-3 corresponding to 5.1 x 10(-17) to 2.55 x 10(-15) gcm-3 43Tc99m. The application of the detector for the analysis of some radiopharmaceuticals is presented.     

Ant colony optimization for power plant maintenance scheduling optimization—a five-station hydropower system

A number of algorithms have been developed for the optimization of power plant maintenance schedules. However, the true test of such algorithms occurs when they are applied to real systems. In this paper, the application of an Ant Colony Optimization formulation to a hydropower system is presented. The formulation is found to be effective in handling various constraints commonly encountered in practice. Overall, the results obtained using the ACO formulation are better than those given by traditional methods using engineering judgment, which indicates the potential of ACO in solving realistic power plant maintenance scheduling problems.     

Synthesis and thiol–ene photopolymerization of allyl‐ether functionalized dendrimers

Well‐defined, allyl‐ether functional, first‐generation dendrimers have been synthesized. The convergent growth approach was utilized, using the anhydride of the allyl‐ether terminated building block. Three different core moieties were used: trimethylolpropane, trisphenol, and ditrimethylolpropane. The coupling reactions proceeded in good yields and all compounds were characterized by NMR, MALDI‐TOF, and SEC. The allyl‐terminated dendrimers were crosslinked by thiol–ene chemistry, using a multifunctional thiol, TriThiol, to give clear and smooth films. The photopolymerization was conducted in the presence of a photoinitiator, Irgacure 651, and no traces of either allyl‐ether groups or thiols were observed by FT‐Raman after cure. All crosslinked films were characterized with respect to mechanical (DMA) and thermal (DSC) properties. It was found that homogeneous networks were formed and that the core functionality and structure had little effect on the network properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1339–1348, 2008     

Computer Simulation Studies of Anisotropic Systems XVI. The Smectic E-Smectic B Transition

We have investigated the smectic E-smectic B transition with the aid of a model smectogen whose properties have been calculated using the Monte Carlo technique of computer simulation. The lath-like mesogenic molecules are defined to lie in a plane with their centres on a triangular lattice and with their long axes orthogonal to the smectic layer. The quadrupolar interaction, restricted to nearest neighbours, is assumed to be responsible for the herring-bone arrangement of the molecular short axes, characteristic of the smectic E phase. The computer simulations have been employed to evaluate both thermodynamic and structural parameters as a function of temperature. The model smectogen is found to exhibit a continuous transition at which the long range herring-bone structure of the smectic E phase is destroyed only to be replaced by the analogous short range structure of the smectic B. Where possible the results simulated for the model smectogen are compared with the behaviour of real mesogens and the predictions of molecular field theories for the transition. In particular, contact is made with X-ray diffraction studies of the two phases by using optical techniques to generate the diffraction patterns associated with configurations produced by the simulation. The model is found to be in good accord with experiment but the molecular field prediction of the smectic E-smectic B transition temperature is shown to be poor.     

A versatile route to 3-(pyrimidin-4-yl)-imidazo[1,2-a]pyridines and 3-(pyrimidin-4-yl)-pyrazolo[1,5-a]pyridines

A two-step synthesis of 3-(2-chloropyrimidin-4-yl)imidazo[1,2-a]pyridines is presented. The late stage elaboration of the imidazopyridine through a cyclocondensation allows a rapid access to a variety of substitution patterns. The intermediate enol ethers were obtained from inexpensive reagents in a ligand-free Heck coupling. This methodology has been extended to the formation of pyrazolo[1,5-a]pyridines via a formal 1,3-dipolar cycloaddition.     

Forward scatter target strength extraction in a marine environment (L)

A 48 m rail with a moving receiver was used to measure forward scattering from a spherical shell lying on the bottom in the Gulf of Mexico. The target was mid-way between the source and rail, on a line from the source bisecting the rail. The major obstacle to the measurement of forward scattering is the much stronger source signal which overlaps the scattered signal in space and time. Here, forward scattered target strength is obtained by processing the received signals using a wavenumber filter to remove the incident wave. The result compares favorably to that obtained from numerical predictions.     

Affine gravity,Palatini formalism and charges

Affine gravity and the Palatini formalism contribute both to produce a simple and unique formula for calculating charges at spatial and null infinity for Lovelock type Lagrangians whose variational derivatives do not depend on second-order derivatives of the field components. The method is based on the covariant generalization due to Julia and Silva of the Regge–Teitelboim procedure that was used to define properly the mass in the classical formulation of Einstein’s theory of gravity. Numerous applications reproduce standard results obtained by other secure but mostly specialized method like in ADM energy for asymptotically flat spacetimes and in Abbot and Deser for asymptotically de Sitter and anti-de Sitter spacetimes, both at spatial infinity. As a novel application we calculate the Bondi energy loss in five dimensional gravity, based on the asymptotic solution given by Tanabe et al. and obtain, as expected, the same result. We also give the for Einstein–Gauss–Bonnet gravity and find the superpotential for Lovelock theories of gravity when the number of dimensions tends to infinity with maximally symmetrical boundaries. The paper is written in standard component formalism.     

Di­carbonyl­(tropolonato)­rhodium(I), a redetermination

The mol­ecules of the title complex, [Rh(Trop)(CO)₂] (Trop is 2‐hydroxycyclo­hepta‐2,4,6‐trienonate, C₇H₅O₂), exhibit symmetrical but non‐crystallographic square‐planar molecular geometry, with Rh—C distances of 1.825 (10) and 1.826 (9) Å, Rh—O distances of 2.021 (5) and 2.032 (5) Å, and an O—Rh—O bite angle of 79.4 (2)°. Strong Rh⋯Rh and Rh⋯C intermolecular interactions of 3.683 (3) and 3.650 (5) Å, respectively, are also observed.     

(+)‐(2R,3S)‐3‐Bromo‐2‐chloro‐N,N‐diiso­propyl‐3‐phenyl­propan­amide and (+)‐(2R,3S)‐3‐bromo‐2‐chloro‐N‐(4‐nitro­phenyl)‐3‐phenyl­propan­amide

The stereochemistries at positions 2 and 3 of the title compounds, C₁₅H₂₁BrClNO, (I), and C₁₅H₁₂BrClN₂O₃, (II), have been confirmed by X‐ray structural analysis. The halogen atoms adopt an antiperiplanar arrangement in each case.