Synthesis of 4-substituted 5,6-diphenylmorpholine-2,3-diones with two or three chiral centers

Chiral α-aminoalcohols obtained by stereoselective reduction of α-iminoketones have been condensed with oxalyl chloride to afford 4-substituted 5,6-diphenylmorpholine-2,3-diones having two or three chiral centers.     

Uncatalyzed addition of alcohols and amines to the C=N bond of the monoimine from benzil and 2-aminopyridine

The monoimine easily formed bydirect condensation between benzil and 2-aminopyridine adds alcohols and amines to the imine bond without catalysis. A concerted mechanism is proposed.     

Gamow-teller strengths of the inverse beta transition 176Yb-->176Lu for spectroscopy of proton-proton and other sub-MeV solar neutrinos

Discrete Gamow-Teller (GT) transitions 176Yb-->176Lu at low excitation energies have been measured via the ( 3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(nu) = 301 and 445 keV for neutrino ( nu) capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(nu) in Yb-Lu indicate that Yb-based nu detectors are well suited for a direct measurement of the sub-MeV solar electron-neutrino ( nu(e)) spectrum including pp neutrinos.     

Hyperfine and Magnetic Characterization of Fe Particles Hosted in Carbon Nanocapsules

Iron particles encaged in carbon nanocapsules have been produced by the Krätschmer–Huffmann carbon-arc discharge method. Soot, collarette and cathode samples have been characterized by Mössbauer spectroscopy and magnetic measurements in the temperature range 4.2–300 K. Different iron phases and iron-carbon solid solutions have been detected in our samples. The Einstein model has been used to evaluate the coupling constant between the particles and their environment, yielding values of the order 1–10 N/m. Irreversibilities observed at ZFC and FC curves for soot samples would suggest the presence of superparamagnetism only if the particles presented a blocking temperature above 300 K.     

Random coefficient differential equation models for bacterial growth

In the mathematical modeling of population growth, and in particular of bacterial growth, parameters are either measured directly or determined by curve fitting. These parameters have large variability that depends on the experimental method and its inherent error, on differences in the actual population sample size used, as well as other factors that are difficult to account for. In this work the parameters that appear in the Monod kinetics growth model are considered random variables with specified distributions. A stochastic spectral representation of the parameters is used, together with the polynomial chaos method, to obtain a system of differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time.     

A fractional order epidemic model for the simulation of outbreaks of influenza A(H1N1)

In this paper, we propose a nonlinear fractional order model in order to explain and understand the outbreaks of influenza A(H1N1). In the fractional model, the next state depends not only upon its current state but also upon all of its historical states. Thus, the fractional model is more general than the classical epidemic models. In order to deal with the fractional derivatives of the model, we rely on the Caputo operator and on the Grünwald–Letnikov method to numerically approximate the fractional derivatives. We conclude that the nonlinear fractional order epidemic model is well suited to provide numerical results that agree very well with real data of influenza A(H1N1) at the level population. In addition, the proposed model can provide useful information for the understanding, prediction, and control of the transmission of different epidemics worldwide. Copyright © 2013 John Wiley & Sons, Ltd.     

Scars of the Wigner Function

We propose a picture of Wigner function scars as a sequence of concentric rings along a two-dimensional surface inside a periodic orbit. This is verified for a two-dimensional plane that contains a classical hyperbolic orbit of a Hamiltonian system with 2 degrees of freedom. The stationary wave functions are the familiar mixture of scarred and random waves, but the spectral average of the Wigner functions in part of the plane is nearly that of a harmonic oscillator and individual states are also remarkably regular. These results are interpreted in terms of the semiclassical picture of chords and centers.