Large-area phoswich balloon experiment for hard-X-ray astronomy

Summary We describe a balloon experiment, currently in the marking, devoted to the observation of celestial X-ray sources. The main features of the X-ray telescope are summarized as follows. It operates in the energy band from 20 to 300 keV. Its energy resolution is about 17% at 60 keV. Under the hypothesis of 10⁴ s of observing time, 3 mbar of residual atmospheric pressure and 3σ of statistical significance, the expected sensitivity of the instrument is 2·10⁻⁶ photons/cm² s keV in the (20÷200) keV energy band, corresponding to about 1 milliCrab. Its high sensitivity allows us to detect both time variability in the flux and cyclotron lines in the spectra of X-ray sources. It has a field of view of 3° FWHM and has the possibility of resolving complex fields by using multipitch modulation collimators. With such a configuration its angular resolution is about 10′. Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984.     

Single-atom effects in high-order harmonic generation: role of carrier-envelope phase in the few-optical-cycle regime

Recently the role of the carrier-envelope phase of few-optical-cycle light pulses on high-order harmonic generation has been experimentally observed. By using a three-dimensional nonadiabatic propagation model, we show that the observed carrier-envelope phase dependence of the spectral characteristics of the harmonic radiation is essentially a single-atom effect. Nonadiabatic single-atom response has been calculated in the framework of the saddle-point approximation. PACS 42.65.Ky; 42.65.Re; 42.50.Hz     

Two-step laser activation of hematoporphyrin derivative

A new photoactivation mechanism of hematoporphyrin derivative is presented. This process, based on the sequential absorption of two photons, leads to the production of cytotoxic radicals of HpD. The cytocidal efficiency is demonstrated by in vitro experiments.     

Opening of thiiranes: preparation of orthogonal protected 2-thioglyceraldehyde.

Treatment of acrolein diethyl acetal sulfide 8 with methanesulfenyl bromide at low temperature results in an efficient thiirane ring opening to a halo disulfide 9. The bromine in this halo disulfide is easily substituted by silver acetate, sodium azide, sodium iodide, and silver nitrate. Treatment of 9 with tetrabutylammonium acetate yields a novel dehydrohalogenation product 12. Silica gel converts bromide 9 into a disulfide-substituted version of acrolein 15. The orthogonal-protected version of 2-thioglyceraldehyde 13 can be deprotected to a useful form of this aldehyde.     

Emerging Direct Targeting β-Catenin Agents

Aberrant accumulation of β-catenin in the cell nucleus as a result of deregulation of the Wnt/β-catenin pathway is found in various types of cancer. Direct β-catenin targeting agents are being researched despite obstacles; however, specific β-catenin drugs for clinical treatments have not been approved so far. We focused on direct β-catenin targeting of potential therapeutic value as anticancer agents. This review provides recent advances on small molecule β-catenin agents. Structure-activity relationships and biological activities of reported inhibitors are discussed. This work provides useful knowledge in the discovery of β-catenin agents.     

The Dynamical Structure Function of the One‐Component Plasma Revisited

We present high precision Molecular Dynamics simulations for the dynamical structure function, S (k, ω), of the classical Coulomb One Component Plasma (OCP), for a wide range of the coupling parameter Γ (from 0.05 to 10 000). We follow the positive‐to‐negative transition of the slope of the ω (k) dispersion curve at small wave numbers caused by the onset of correlations with increasing coupling. The high signal‐to‐noise ratio of the data over several orders of magnitude allows examination of a wide dynamical range of S (k, ω), including extreme values of ω and k, and the identification of waves at higher harmonics of the plasma frequency. Sum rules are found to be accurately satisfied. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stacked conjugated oligomers as molecular models to examine interchain interactions in conjugated materials

Previous studies of the redox states of linear conjugated oligomers as models for polarons and bipolarons in conjugated polymers do not fully address the influence of intermolecular interactions on the electronic structure of conjugated systems in the solid state. Fusion of oligothiophenes onto a bicyclo[4.4.1]undecane core holds the conjugated oligomers in a permanent cofacial stack. One- and two-electron oxidation of the stacked oligomers affords mono(radical cation)s and dications that serve as models for polarons and bipolarons in p-doped conjugated polymers and demonstrates the effect of pi-stacking on the electronic structure of these species.