A new measurement of the 122Sb half-life

Journal of Radioanalytical and Nuclear Chemistry - Following significant discrepancies observed when decay-correcting 122Sb γ-peak count rates to a reference time, we looked at the literature...     

Controlling Stereoselectivity in the Aminocatalytic Enantioselective Mannich Reaction of Aldehydes with In Situ Generated N‐Carbamoyl Imines

A simple and convenient method for the direct, aminocatalytic, and highly enantioselective Mannich reactions of aldehydes with in situ generated N‐carbamoyl imines has been developed. Both α‐imino esters and aromatic imines serve as suitable electrophilic components. Moreover, the judicious selection of commercially available secondary amine catalysts allows selective access to the desired stereoisomer of the N‐tert‐butoxycarbonyl (Boc) or N‐carbobenzyloxy (Cbz) Mannich adducts, with high control over the syn or anti relative configuration and almost perfect enantioselectivity. Besides the possibility to fully control the stereochemistry of the Mannich reaction, the main advantage of this method lies in the operational simplicity; the highly reactive N‐carbamate‐protected imines are generated in situ from stable and easily handled α‐amido sulfones.     

Mitigating cascades in sandpile models: an immunization strategy for systemic risk?

We use a simple model of distress propagation (the sandpile model) to show how financial systems are naturally subject to the risk of systemic failures. Taking into account possible network structures among financial institutions, we investigate if simple policies can limit financial distress propagation to avoid system-wide crises, i.e. to dampen systemic risk. We therefore compare different immunization policies (i.e. targeted helps to financial institutions) and find that the information coming from the network topology allows to mitigate systemic cascades by targeting just few institutions.     

Copper‐Catalyzed Coupling Reaction of 2‐Thioxo‐4‐quinazolinone and Thieno[3,2‐d]pyrimidin‐4‐one Methane Sulphonamide with Aryl Iodides: Preparation of Potential COX‐2 Selective Inhibitors

Thio‐aryl methane sulfonamide derivatives of 4‐quinazolinone and thieno[2,3‐d]pyrimidin‐4‐one were synthesized using powdery copper/copper(I) iodide as catalyst; their structural elucidation is also reported. These derivatives were planned as sulfur bioisosteres of selective COX‐2 inhibitor drugs.     

Voltammetric platform for detection of 2,4,6-trinitrotoluene based on a molecularly imprinted polymer

New methods for determination of explosive substances as, for example, 2,4,6-trinitrotoluene (TNT), in a rapid way and at low cost are highly required. An electrochemical platform has been here developed with good characteristics of low dimension, fast response, low cost, and high selectivity. It is based on a commercially available screen printed cell with graphite ink working and auxiliary electrodes and a silver ink quasi-reference electrode. The whole cell is covered with a thick layer of cation exchanging acrylic polymer molecularly imprinted with 2,4,6-trinitrotoluene. The polymeric layer acts at the same time as electrolytic medium and selective receptor. It has been demonstrated that, in this medium, 2,4,6-trinitrotoluene is electroactive at graphite electrode, being reduced by a non-reversible reaction. The peak current (differential pulse voltammogram) is proportional to TNT concentration with limit of detection for TNT around 5?×?10^?7?M and linearity range up to 2?×?10^?5?M. The selectivity for TNT relative to other reducible compounds as, for example, nitroaromatic derivatives, and to other possible interfering substances, as negatively charged ions, is good. Measurements can be performed in not de-aerated solution and in small volumes (20 μl), so that the proposed platform is very promising for in situ determinations.

CO adsorption on Ni(1 0 0): Evidences for a weakly bound phase by HREELS measurements

The vibrational properties of CO on Ni(1 0 0) were investigated by high resolution electron energy loss spectroscopy. Loss measurements were performed as a function of temperature and CO exposures. At room temperature, regardless of CO coverage, we found stretching energies at 250 meV and 240 meV, assigned to CO at atop and bridge sites, respectively. At low temperature and for CO exposures lower than 0.6 L, the loss spectra showed a single stretching peak at 240 meV which is assigned to CO at bridge sites. For higher doses, a new intense peak at 260 meV appeared in the loss spectra. The rise of this new loss strongly influenced the intensity of the peak at 240 meV suggesting the occurrence of dipole couplings between adjacent CO molecules. This unusual high stretching frequency leads us to assign the peak at 260 meV to the stretching vibration of CO molecules which are weakly bonded to the Ni surface. We suggest that the formation of this phase is due to an electronic effect arising from a reduced back donation of electrons into the empty π orbital of CO.     

Geometry of PDE's. II: Variational PDE's and integral bordism groups

In the framework of the geometry of PDE's, we classify variational equations of any order with respect to their formal properties. Following our previous results [A. Prástaro, Quantized Partial Differential Equations, World Scientific, Singapore, 2004], we relate constrained variational PDE's to their integral bordism groups. In this way we are able to characterize global solutions of constrained variational PDE's and to relate them to the structure of global solutions for the corresponding constraint equations. Some applications are also considered.     

Synthetic approaches to bridgehead nitrogen methanesulfonamide derivatives of 3‐amino‐2‐thioxo‐2,3‐dihydrothieno[2,3‐d]pyrimidin‐4(1H)‐ones,potential cox‐2 selective inhibitors

Methane sulfonamide derivatives of 3‐amino‐2‐thioxo‐2,3‐dihydrothieno[2,3‐d]pyimidin‐4(1H)‐one, potential selective COX‐2 inhibitors, were synthesized and their structural elucidation is here reported. Some derivatives, at 10 μM concentration, showed a significant percentage of inhibition in some in vitro experiments.