Eleven-dimensional CJS supergravity and the D'Auria–Fré group

An action for eleven-dimensional standard supergravity genuinely invariant under the D'Auria–Fré group is proposed. The construction of the action is carried out through a generalization of the Stelle–West–Grignani–Nardelli formalism. The action is genuinely invariant under this group without the need to impose auxiliary conditions such as a torsion-free condition.     

The calculation of neutron self-shielding factors of a group of isolated resonances

The resonance neutron self-shielding factor, G _res, is required in neutron metrology and activation data analysis. In a previous paper, the authors have shown that a dimensionless variable can be introduced which converts the dependence of G _res on the physical and nuclear properties of the material samples into an universal curve, valid for the isolated resonances of any nuclide. This work presents a methodology based on the universal curve, which enables to calculate G _res for a group of isolated resonances by weighting its individual contributions. A good agreement was reached with results calculated by the MCNP code and with experimental values for Mo foils and wires. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Oxidation of Luminol an Experiment to Maximize the Efficiency of Chemiluminescence from Luminol

In this work, seven inorganic salts, KCl, Na₂SO₄, MgSO₄-7H₂O, ZnCl₂, Na₂CrO₄, CuSO₄-5H₂O, and K₃[Fe(CN)₆], were used as catalysts to induce chemiluminescent luminol oxidation in alkaline aqueous media. It was observed that simple salts containing either Mg²⁺, Zn²⁺, Na⁺ and K⁺ cations or SO₄^2– and Cl^– anions, are not active as catalysts. On the other hand, the relative order of activity detected for the active chemiluminescent salts containing Fe(III), Cu(II) and Cr(VI) cations is K₃[Fe(CN)₆] < CuSO₄-5H₂O < Na₂CrO₄. The intensity of the emitted light agrees with the standard reduction potentials of the corresponding redox couple and with the presence of paramagnetic species in the aqueous solutions. The inhibition effect of mannitol was also studied.     

Solid-state 2H NMR structure of retinal in metarhodopsin I

The structural and photochemical changes in rhodopsin due to absorption of light are crucial for understanding the process of visual signaling. We investigated the structure of trans-retinal in the metarhodopsin I photointermediate (MI), where the retinylidene cofactor functions as an antagonist. Rhodopsin was regenerated using retinal that was (2)H-labeled at the C5, C9, or C13 methyl groups and was reconstituted with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. Membranes were aligned by isopotential centrifugation, and rhodopsin in the supported bilayers was then bleached and cryotrapped in the MI state. Solid-state (2)H NMR spectra of oriented rhodopsin in the low-temperature lipid gel state were analyzed in terms of a static uniaxial distribution (Nevzorov, A. A.; Moltke, S.; Heyn, M. P.; Brown, M. F. J. Am. Chem. Soc. 1999, 121, 7636-7643). The line shape analysis allowed us to obtain the methyl bond orientations relative to the membrane normal in the presence of substantial alignment disorder (mosaic spread). Relative orientations of the methyl groups were used to calculate effective torsional angles between the three different planes that represent the polyene chain and the beta-ionone ring of retinal. Assuming a three-plane model, a less distorted structure was found for retinal in MI compared to the dark state. Our results are pertinent to how photonic energy is channeled within the protein to allow the strained retinal conformation to relax, thereby forming the activated state of the receptor.