Preparation of a new chiral non-racemic sulfur-containing diselenide and applications in asymmetric synthesis

The synthesis of the new chiral non-racemic sulfur-containing diselenide, di-2-methoxy-6-[(1S)-1-(methylthio)ethyl]phenyl diselenide, is described. When treated with ammonium persulfate this diselenide is transformed into the corresponding selenenyl sulfate, which acts as a strong electrophilic reagent and adds to alkenes, in the presence of methanol or water, to afford the products of selenomethoxylation or selenohydroxylation, respectively, with excellent diastereoselectivities. Starting from alkenes containing internal nucleophiles, asymmetric cyclofunctionalization reactions also resulted in good chemical yields, complete regioselectivities, and high diastereoselectivities. This sulfur-containing diselenide can also be used in catalytic amounts to promote one-pot selenenylation-deselenenylation processes, from which several types of products can be obtained in high yield and with good enantiomeric excess.     

Beta-functionalised polythiophenes as microelectrode modifiers in low conductive media

A study on polythiophene coated microelectrodes is reported, the goal being that of checking the capability of these electrochemical systems to work in low conductive media. The possibility of electrochemically p-doping the polymer in the presence of very low concentrations or even in the absence of supporting electrolyte in the solution is ascertained, opening the way to the use of similar systems in pure solvent media. This result is obtained in such conditions that the presence of residual charges--and corresponding counterions--trapped inside the film coating can be reasonably hypothesised.     

Cosmology of a brane radiating gravitons into the extra dimension

We study in a self-consistent way the impact of the emission of bulk gravitons on the (homogeneous) cosmology of a three-brane embedded in a five-dimensional spacetime. In the low energy regime, we recover the well known result that the bulk affects the Friedmann equation only via a radiationlike term C/a(4), called dark or Weyl radiation. In the high energy regime, we find that the Weyl parameter C is no longer constant but grows rapidly. Consequently, C today is determined by the past history of the brane universe and depends on the number of relativistic degrees of freedom at the high/low energy transition.     

Neural markers of a greater female responsiveness to social stimuli

Background  

There is fMRI evidence that women are neurally predisposed to process infant laughter and crying. Other findings show that women might be more empathic and sensitive than men to emotional facial expressions. However, no gender difference in the brain responses to persons and unanimated scenes has hitherto been demonstrated.     

Laguerre geometry of surfaces with plane lines of curvature

We study surfaces with plane lines of curvature in the framework of Laguerre geometry and provide explicit representation formulae for these surfaces in terms of a potential function. As an application, we explicitly integrate allL- minimal surfaces with plane curvature lines. Partially supported by MURST 40.     

119Sn mössbauer,IR, 1H NMR spectroscopic and thermal decomposition studies on organotin(IV) adducts with glycylglycine

The complexes R₂SnCl₂·(H₂glygly), (H₂glygly = glycylglycine) (R = Me, Buⁿ, Octⁿ, Ph) and RSnCl₃·(H₂glygly)     

Rosigenin,an unusual metabolite from mycosphaerella rosigena1

A new metabolite, 3,6-dimethyl-4,10-dihydroxy-2-oxaspiro[4.5]dec-7-en-1,9-dione (1a), was isolated from a strain of Mycosphaerella rosigena grown on potato-agar medium. The structure was determined on the basis of chemical and spectroscopic evidence and confirmed by X-ray analysis.     

Full counting statistics with spin-sensitive detectors reveals spin singlets

We study the full counting statistics of electric current to several drain terminals with spin-dependent entrance conductances. We show that the statistics of charge transfers can be interpreted in terms of single electrons and spin-singlet pairs coming from the source. If the source contains transport channels of high transparency, a significant fraction of electrons comes in spin-singlet pairs.     

Graded Cluster Expansion for Lattice Systems

In this paper we develop a general theory which provides a unified treatment of two apparently different problems. The weak Gibbs property of measures arising from the application of Renormalization Group maps and the mixing properties of disordered lattice systems in the Griffiths’ phase. We suppose that the system satisfies a mixing condition in a subset of the lattice whose complement is sparse enough namely, large regions are widely separated. We then show how it is possible to construct a convergent multi-scale cluster expansion.The authors acknowledge the support of Cofinanziamento MIUR.