Rapid synthesis of 3-amino-imidazopyridines by a microwave-assisted four-component coupling in one pot

The rapid and efficient synthesis of various 2,6-disubstituted-3-amino-imidazopyridines using a microwave-assisted one-pot cyclization/Suzuki coupling approach is described. The utility of a 2-aminopyridine-5-boronic acid pinacol ester as a robust and versatile building block for the synthesis of diverse compound libraries is emphasized. The boronate functional group is remarkably tolerant to the Lewis acid catalyzed cyclizations, and the subsequent Pd(0)-catalyzed Suzuki coupling reactions proceed cleanly in the presence of magnesium salts. This work highlights the vast potential of microwave-assisted, metal-catalyzed, multicomponent reactions.     

Self-referencing, spectrally, or spatially encoded spectral interferometry for the complete characterization of attosecond electromagnetic pulses

We propose a method for the complete characterization of attosecond duration electromagnetic pulses produced by high harmonic generation in an atomic gas. Our method is based on self-referencing spectral interferometry of two spectrally sheared extreme ultraviolet pulses, which is achieved by pumping the harmonic source with two sheared optical driving pulses. The resulting interferogram contains sufficient information to completely reconstruct the temporal behavior of the electric field. We demonstrate that such a method is feasible, and outline two possible experimental configurations.     

Intense self-compressed, self-phase-stabilized few-cycle pulses at 2 microm from an optical filament

We report the compression of intense, carrier-envelope phase stable mid-IR pulses down to few-cycle duration using an optical filament. A filament in xenon gas is formed by using self-phase stabilized 330 microJ 55 fs pulses at 2 microm produced via difference-frequency generation in a Ti:sapphire-pumped optical parametric amplifier. The ultrabroadband 2 microm carrier-wavelength output is self-compressed below 3 optical cycles and has a 270 microJ pulse energy. The self-locked phase offset of the 2 microm difference-frequency field is preserved after filamentation. This is to our knowledge the first experimental realization of pulse compression in optical filaments at mid-IR wavelengths (lambda>0.8 microm).     

Laser-induced fluorescence spectroscopy of ionic clusters between organic cations and inert gases

The Laser-induced fluorescence spectra of ionic cluster C₆F₆⁺·X_n, where X = He, Ne, or Ar, are obtained by multiphoton ionization of C₆F₆ seeded in an inert gas expansion. Spectral information concerning the red-shifts and linewidths of the ionic cluster are reported and observations relevant to their formation mechanisms are offered.     

Centred TVD schemes for hyperbolic conservation laws

New first- and high-order centred methods for conservation lawsare presented. Convenient TVD conditions for constructing centredTVD schemes are then formulated and some useful results areproved. Two families of centred TVD schemes are constructedand extended to nonlinear systems. Some numerical results arealso presented.     

Alpha B-Crystallin in Muscle Disease Prevention: The Role of Physical Activity

HSPB5 or alpha B-crystallin (CRYAB), originally identified as lens protein, is one of the most widespread and represented of the human small heat shock proteins (sHSPs). It is greatly expressed in tissue with high rates of oxidative metabolism, such as skeletal and cardiac muscles, where HSPB5 dysfunction is associated with a plethora of human diseases. Since HSPB5 has a major role in protecting muscle tissues from the alterations of protein stability (i.e., microfilaments, microtubules, and intermediate filament components), it is not surprising that this sHSP is specifically modulated by exercise. Considering the robust content and the protective function of HSPB5 in striated muscle tissues, as well as its specific response to muscle contraction, it is then realistic to predict a specific role for exercise-induced modulation of HSPB5 in the prevention of muscle diseases caused by protein misfolding. After offering an overview of the current knowledge on HSPB5 structure and function in muscle, this review aims to introduce the reader to the capacity that different exercise modalities have to induce and/or activate HSPB5 to levels sufficient to confer protection, with the potential to prevent or delay skeletal and cardiac muscle disorders.     

Influence of olive (cv Grignano) fruit ripening and oil extraction under different nitrogen regimes on volatile organic compound emissions studied by PTR-MS technique

Volatile organic compounds of extra virgin olive oils obtained from the local Italian cultivar Grignano were measured by proton transfer reaction–mass spectrometry (PTR-MS). Oils were extracted by olives harvested at different ripening stages across veraison, performing each extraction step and the whole extraction process in nitrogen atmosphere to observe the changes in the volatile profiles of the oils. Principal component analysis carried out on the full spectral signature of the PTR-MS measurements showed that the stage of ripening has a stronger effect on the global definition of volatile profiles than the use of nitrogen during oil extraction. The fingerprint-like chemical information provided by the spectra were used to construct a heat map, which allowed the dynamical representation of the multivariate nature of mass evolution during the ripening process. This provided the first evidence that some groups of volatile organic compounds displayed a time course of regulation with coordinated increasing or decreasing trends in association with specific stages of fruit ripening.