Conservative methods for the Toda lattice equations

We are concerned with the numerical integration of the Todalattice equations by using different conservative methods. Numericalexperiments suggest that the global error for isospectral schemesdecreases exponentially with time but it is almost constantfor either symplectic or more general integrators. We providea theoretical explanation for these experimental findings.     

Ground-state properties of neutron magic nuclei

A systematic study of the ground-state properties of the entire chains of even–even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82, and 126 has been carried out using relativistic mean-field plus Bardeen–Cooper–Schrieffer approach. Our present investigation includes deformation, binding energy, two-proton separation energy, single-particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using nonrelativistic approach (Skyrme–Hartree–Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip-lines, the (Z, N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.     

Nanostructured zirconium oxide based genosensor for Escherichia coli detection

A deoxyribonucleic acid (DNA) biosensor has been fabricated via immobilization of 17 base terminal single stranded DNA (ssDNA) identified from the 16s rRNA coding region of Escherichia coli onto sol–gel derived nanostructured zirconium oxide (NanoZrO₂) film. An oligonucleotide probe with a terminal 5′-phosphate group has been attached to the surface of the electrode via affinity of NanoZrO₂ for phosphate. The results of hybridization studies carried out with the complementary, non-complementary and genomic DNA reveal that ssDNA/NanoZrO₂/ITO bioelectrode has a high selectivity and sensitivity towards hybridization detection with limits of 10^?6–10⁶ pM of complementary DNA.     

Supramolecular self-assembly of dendronized polymers: reversible control of the polymer architectures through acid-base reactions

Acid-base switchable supramolecular dendronized polyacetylenes (DPAs) with increasing steric bulk on going from generation one [G1] to three [G3], were constructed using multiple self-assembly processes between Fréchet-type [G1]-[G3]-dendritic dialkylammonium salts and a dibenzo[24]crown-8-containing polymer. The formation of the supramolecular systems is acid-base switchable to either an ON (rodlike dendronized polymers) or an OFF (flexible polymers) state. Thus, by controlling the superstructures of the supramolecular polymers with the [G1]-[G3] dendrons, it is possible to induce conformational changes within the polymer backbones. The supramolecular dendronized polymers, as well as their threading-dethreading properties, were characterized by (1)H NMR and UV absorption spectroscopies, gel permeation chromatography (GPC) and light scattering (LS). Independent measures of molecular weight (GPC, LS) indicate that DPAs behave as increasingly rigid macromolecules with each generation in solution. Molecular dynamics simulations of each DPA suggest that the lengths of the polymer backbones increase accordingly. Atomic force microscopy of the [G3]-dendronized polystyrene (DPS), as well as the DPAs, reveal surface morphologies indicative of aggregated superstructures.     

On the Sachs bound in stress-induced phase transformations in polycrystalline scalar shape-memory alloys

We consider stress–induced transformations of polycrystalline shape–memory alloys which are so–called scalar materials. In this case the Sachs bound on the phase transformation yield stress turns out to be sharp. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structures and energetics of electrosprayed uracil(n)Ca2+ clusters (n = 14-4) in the gas phase

Clusters of uracil (U) about a calcium dication, U(n)Ca(2+) (n = 14-4), have been studied in the gas phase by both experimental and theoretical methods. Temperature dependent blackbody infrared radiative dissociation (BIRD) experiments were performed on U(n)Ca(2+) clusters with n = 14-5 and the observed Arrhenius parameters are reported here. Master equation modeling of the BIRD kinetics data was carried out to determine threshold dissociation energies. Initial geometry calculations were performed using the B3LYP density functional and 3-21G(d) basis set. A sample of ten conformations per cluster was obtained through a simulated annealing study. These structures were optimized using B3LYP/6-31G(d) level of theory. Fragment-based hybrid many body interaction (HMBI) MP2/6-311++G(2df,2p)/Amoeba calculations were performed on representative conformations to determine theoretical binding energies. Results were examined in relation to cluster size (n). A significant increase in the energy required to remove uracil from U(6)Ca(2+) when compared to larger clusters supports previous reports that the calcium ion is coordinated by six uracil molecules in the formation of an inner shell. For clusters larger than n = 6, an odd-even alternation in threshold dissociation energies was observed, suggesting that the outer shell uracil molecules bind as dimers to the inner core. Proposed binding schemes are presented. Multiple structures of U(5)Ca(2+) are suggested as being present in the gas phase where the fifth uracil may be either part of the first or second solvation shell.     

Anomalous variation of the Lamb-M?ssbauer factor at the magnetic transition temperature in magnetoelectric?GaFeO(3)

Temperature-dependent (57)Fe M?ssbauer spectroscopy (5-723?K) and neutron diffraction (2-290?K) measurements are carried out on polycrystalline magnetoelectric GaFeO(3). From the neutron diffraction data, evidence for the magnetostriction and increased disorder at Fe sites close to the ferrimagnetic Curie transition temperature (T(C)) is observed. From the M?ssbauer data, it is observed that the Lamb-M?ssbauer factor as a function of temperature f(T), which is related to the integral over the first Brillouin zone of the phonon spectrum, shows a unequivocal variation at the T(C). The observations are discussed in terms of spin-phonon coupling. The observed average hyperfine fields from (57)Fe M?ssbauer spectra match with the bulk magnetization data. A critical exponent (β) of 0.38?±?0.02 and a Debye temperature (θ(D)) of ～350?K is estimated from the (57)Fe M?ssbauer data.