Lipase-catalyzed monoprotection of 1,4-diols in an organic solvent using vinyl benzoate as acyl transfer agent

Lipase from Mucor miehei (MML) has been selected as the most suitable enzyme to catalyze the efficient monobenzoylation of 1,4-diols using vinyl benzoate as acyl transfer reagent in tert-butyl methyl ether. The regioselectivity of the monobenzoylation of 2-substituted-1,4-diols has been studied as well.     

Zinc(II), cadmium(II) and mercury(II) halide pyrrolidine-2-thione complexes

Summary White crystalline complexes of general formula ML₂X₂, where M = Zn, Cd, Hg; X = Cl, 13r, I and L = pyrrolidine-2-thione, were prepared and studied by i.r. spectroscopy in the 4000-200 cm^–1 range. Evidence for coordination of the ligand to the metal through sulphur was found in each case. The previous assignment of the band present in the ligand at 1110 cm^–1 to the(CS) fundamental is discussed.This work was supported by the National Research Council (C.N.R.) of Italy.     

Direct observation of tunneling and nonlinear self-trapping in a single bosonic Josephson junction

We report on the first realization of a single bosonic Josephson junction, implemented by two weakly linked Bose-Einstein condensates in a double-well potential. In order to fully investigate the nonlinear tunneling dynamics we measure the density distribution in situ and deduce the evolution of the relative phase between the two condensates from interference fringes. Our results verify the predicted nonlinear generalization of tunneling oscillations in superconducting and superfluid Josephson junctions. Additionally, we confirm a novel nonlinear effect known as macroscopic quantum self-trapping, which leads to the inhibition of large amplitude tunneling oscillations.     

Asymmetric Landau-Zener tunneling in a periodic potential

Using a simple model for nonlinear Landau-Zener tunneling between two energy bands of a Bose-Einstein condensate in a periodic potential, we find that the tunneling rates for the two directions of tunneling are not the same. Tunneling from the ground state to the excited state is enhanced by the nonlinearity, whereas in the opposite direction it is suppressed. These findings are confirmed by numerical simulations of the condensate dynamics. Measuring the tunneling rates for a condensate of rubidium atoms in an optical lattice, we have found experimental evidence for this asymmetry.     

Highly reduced iron-doped lithium niobate for optoelectronic tweezers

We investigate the applicability of highly reduced lithium niobate samples doped with iron for the use as optoelectronic tweezers. Increasing the reduction degree of Fe-doped lithium niobate is well known to increase the photoconductivity and reduce the writing time of internal space-charge fields. Based on our measurements of the photorefractive properties, we determine the optimal conditions for dielectrophoretic trapping and present the application of Fe-doped lithium niobate as optoelectronic tweezers. For higher reduction degrees, an unexpected decrease in the photovoltaic current density and the saturation space-charge field is reported.     

1H, 13C and 15N NMR assignments for N6‐isopentenyladenosine/inosine analogues

The complete ¹H, ¹³C and ¹⁵N NMR signals assignments of some new isopentenyladenosine analogues were achieved using one‐ and two‐dimensional experiments (gs‐NOESY, gs‐HMQC and gs‐HMBC). Copyright © 2010 John Wiley & Sons, Ltd.     

1H, 13C and 15N NMR assignments for N‐ and O‐acylethanolamines,important family of naturally occurring bioactive lipid mediators

The complete ¹H, ¹³C and ¹⁵N NMR signal assignments of some N‐ and O‐acylethanolamines, important family of naturally occurring bioactive lipid mediators, were achieved using one‐dimensional and two‐dimensional experiments (gs‐HMQC and gs‐HMBC). Copyright © 2012 John Wiley & Sons, Ltd.     

Hybrid organo-inorganic clay with nonionic interlayers. mid- and near-IR spectroscopic studies

The intercalation of organic polymers molecules (i.e., PEGs and BRIJ) into a standard Ca-montmorillonite has been studied by XRD, TG, and IR spectroscopy. The polymer intercalation is confirmed by the increasing of the d(001) in XRD spectra as well as by the complex multisteps thermal decomposition behavior of the organo-clay materials. Mid-IR and diffuse reflectance near-IR spectra of the intercalated materials show the polymer diagnostic bands (CH stretching and deformation mode), shifted or changed in shape by the interaction with the clay matrix. Both PEG 1500 and PEG 4000 based materials are likely intercalated in an extended configuration, similar to the amorphous polymer form. BRIJ intercalated polymer spectra suggest the disordered conformation of the alkilic chain in a prevailing "gauche", poorly packed, conformation. Host montmorillonite IR bands, mainly OH and water stretching and deformation fundamentals, combination, and overtone bands, are reduced in intensity by polymer intercalation, pointing out an interaction, likely through H-bonding and/or a possible substitution of cations hydration water molecules.