Designing an RFQ ring trap for antiproton confinement and trapping and laser cooling Mg+ ions

Summary In the true sense of Bernie's approach to physics, an old idea (the Radiofrequency Quadrupole Trap) was taken and upgraded to be applied to a new area of physics (formation of an antihydrogen beam). During the course of the development work, new applications were identified and immediately put to use. While the collaboration is still pursuing its original goal, formation of antihydrogen by Bernie's reaction, collisions between positronium atoms and antiprotons, many new experiments have been found possible and are actively pursued. These include atomic and nuclear physics studies with ultra-low energy antiprotons ejected from the initial catching trap of the antihydrogen project, and the formation and study of exotic atoms and molecules in ultra-thin targets using trapped antiprotons (an extension of the work by the PS205 collaboration at CERN described elsewhere in this volume [10]). A large physics community has grown around these ideas and may even succeed in obtaining its very own antiproton source, which is a true sign of the recognition of the importance of this field. The work in this area will hopefully continue for many years to come, but we will truly miss the motivation and drive of our friend and colleague, Bernie Deutch.     

8-METHOXYPSORALEN INCREASES DAYTIME PLASMA MELATONIN LEVELS IN HUMANS THROUGH INHIBITION OF METABOLISM

Abstract It is well established that in healthy humans oral intake of 5-or 8-methoxypsoralen (5-and 8-MOP) is followed by a significant increase in plasma melatonin concentrations. The effect of psoralen on rat melatonin has been studied in vitro and in vivo and a stimulation of release or secretion from the pineal gland has been suggested. In this study we examined the time-related changes in plasma concentrations of 8-MOP, melatonin and 6-sulfatoxymelatonin in 15 patients admitted for routine psoralen plus UVA therapy. On the first day of treatment blood samples were collected before, and 30, 60 , 66 and 90 rnin after intake of 8-MOP (0.6 mg/kg). Although the rate of 8-MOP absorption vaned greatly, a significant increase ( P = 0.0002) in melatonin levels was found 60 min after 8-MOP intake. During UVA exposure a strongly correlated decrease in mean melatonin and mean 8-MOP concentrations was found, indicating an effect of UVA radiation, either direct or 8-MOP mediated, on circulating melatonin levels. Plasma 6-sulfatoxymelatonin concentrations decreased significantly between all time points, suggesting inhibition of melatonin metabolism.     

Structure, Stoichiometry, and Phase Purity of Calcium Substituted Lanthanum Manganite Powders

Calcium-doped lanthanum manganite La_1−xCa_xMnO₃, synthesized by the glycine/nitrate method, was characterized by high resolution synchrotron X-ray powder diffraction, electron diffraction, and infrared spectroscopy. A strong correlation was observed between the cooling rate from the calcination temperature and the powder quality, indicating the importance of a homogeneous oxygen stoichiometry. The structure refinement reveals that La_1−xCa_xMnO₃withx=0.2, 0.3, 0.4, and 0.6 has orthorhombic symmetry with space groupPnma. The MnO₆octahedra are fairly symmetrical, but the octahedra are tilted about 20° relative to the ideal perovskite structure. Infrared spectroscopy revealed that only the O–Mn–O bending mode is significantly influenced by the substitution of La with Ca. In La_0.8Ca_0.2MnO₃we found diffraction evidence of a superstructure in domains in some of the grains. We propose that the superstructure in La_0.8Ca_0.2MnO₃is due to ordering of Ca²⁺ions onA(La³⁺) sites in the perovskiteABO₃structure.     

Catalytic enantioselective transamination of alpha-keto esters: an organic approach to enzymatic reactions

The half-transamination reaction of alpha-keto esters with pyridoxamine or 4-picolylamine was found to be catalysed by different metal catalysts in organic solvents giving moderate yields and enantioselectivities of up to 37% ee for methyl-3-indole pyruvate.     

Catalytic Enantioselective Addition of Nitro Compounds to Imines-A Simple Approach for the Synthesis of Optically Active beta-Nitro-alpha-Amino Esters

No AbstractSupporting information for this article is available on the WWW under http://www.angewandte.com or from the author.     

Characterization of thermally sensitive interactions in aqueous mixtures of hydrophobically modified hydroxyethylcellulose and cyclodextrins

Effects of beta-cyclodextrin (beta-CD) or hydroxypropyl-beta-cyclodextrin (HP-beta-CD) addition and temperature on thermodynamic, rheological, and structural features of semidilute solutions of hydroxyethylcellulose (HEC) and its hydrophobically modified analogue (HM-HEC) are reported. Differential scanning calorimetric (DSC) measurements revealed a thermally induced crystal melting transition of beta-CD at high concentrations in solutions of HEC and HM-HEC. No transition with HP-beta-CD was observed in aqueous solution. Viscosity results indicated that at a cosolute concentration of 2 mm, the beta-CD units are threaded onto hydrophobic tails of HM-HEC (C16 groups) to form columnar structures. This arrangement is more effective in the encapsulation of the hydrophobic chains than the monomer hydrophobic deactivation accomplished by the HP-beta-CD units. At cosolute concentrations above 8 mm, no further decoupling of the hydrophobic interactions occurs for any of the cosolutes. Small-angle neutron scattering (SANS) experiments on HM-HEC/beta-CD mixtures suggest that the large-scale association structures in HM-HEC/D(2)O solutions are reduced upon addition of beta-CD, and an interesting temperature effect is observed at 2 mm beta-CD addition. At high beta-CD concentrations and low temperatures, the formation of large beta-CD clusters or crystallites generates cross-links in the HEC and HM-HEC networks, resulting in a viscosity enhancement of several orders of magnitude. This strong temperature effect is not reflected in the structural features probed by SANS.     

Ribozyme-mediated signal augmentation on a mass-sensitive biosensor

Mass-based detection methods such as the quartz crystal microbalance (QCM) offer an attractive option to label-based methods; however the sensitivity is generally lower by comparison. In particular, low-molecular-weight analytes can be difficult to detect based on mass addition alone. In this communication, we present the use of effector-dependent ribozymes (aptazymes) as reagents for augmenting small ligand detection on a mass-sensitive device. Two distinct aptazymes were chosen: an L1-ligase-based aptazyme (L1-Rev), which is activated by a small peptide (MW approximately 2.4 kDa) from the HIV-1 Rev protein, and a hammerhead cleavase-based aptazyme (HH-theo3) activated by theophylline (MW = 180 Da). Aptazyme activity was observed in real time, and low-molecular-weight analyte detection has been successfully demonstrated with both aptazymes.     

Altering associations in aqueous solutions of a hydrophobically modified alginate in the presence of beta-cyclodextrin monomers

The formation of associative networks in semidilute aqueous solutions of hydrophobically modified alginate (HM-alginate) is dependent on intermolecular hydrophobic interactions. Addition of beta-cyclodextrin (beta-CD) monomers to the system provides decoupling of these associations via inclusion complex formation with the polymer hydrophobic tails. This results in a dramatic decrease in the viscoelastic response of the system and a more extended local structure of the polymer chains, as shown by small-angle neutron scattering (SANS) measurements. The zero-shear viscosity decreases about an order of magnitude when the beta-CD concentration is increased from 0 to 12 mm. The lifetime of the associative network decreases strongly with increasing levels of beta-CD addition. These findings clearly demonstrate that the hydrophobic association effect is efficiently reduced as the amount of beta-CD is increased. In the framework of drug delivery, this effect may be useful to improve the release of therapeutic molecules that can be entrapped in the polymer matrix.