Generation of aza-ortho-xylylenes via ring opening of 2-(2-acylaminophenyl)aziridines: application in the construction of the communesin ring system

A new protocol for generating aza-ortho-xylylenes via acid-catalyzed or fluoride-promoted ring opening of 2-(2-acylaminophenyl)aziridines is described. This methodology has been exploited in the rapid construction of a hexacyclic substructure of communesin B.     

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Ohne Zusammenfassung     

Imaging cytoplasmic cAMP in mouse brainstem neurons

Background  

cAMP is an ubiquitous second messenger mediating various neuronal functions, often as a consequence of increased intracellular Ca²⁺ levels. While imaging of calcium is commonly used in neuroscience applications, probing for cAMP levels has not yet been performed in living vertebrate neuronal tissue before.     

Transverse momentum distribution in Pomeron-Pomeron collisions at the CERN ISR

Proton-proton interactions which result in a central cluster of massM _x and two quasi-elastically scattered protons are generally described by Pomeron-Pomeron scattering. A study of this process at ISR energies with the Split Field Magnet detector is carried out in terms of transverse momentum behaviour for the centrally produced system of particles. The inclusivep _T distribution for central hadrons is measured up to 3 GeV/c. Forp _T <1.2 GeV/c, thep _T distribution is exponential. Using a subsample of exclusive events, this exponential shape is shown to originate from a phase-space-like decay ofM _x when convoluted with a transverse component of the pomeron momentum. In the highp _T range, the shape of thep _T distribution strongly depends on Feynman-x of the scattered protons in a way that can be described by hard parton scattering.     

A survey of the (3He, 7Be) reaction at 70 MeV

A study of the (³He, ⁷Be) reaction has been undertaken using a 70 MeV ³He beam. By surveying a wide range of target nuclides, namely ^{12, 13}C, ¹⁶O, ^{24, 26}Mg, ^{40, 42, 44}Ca, ^{58, 60, 62, 64}Ni, ⁹⁰Zr, ^{120, 124}Sn, ¹⁴⁴Sm and ²⁰⁶Pb, systematics of the α-clustering phenomenon were investigated. In addition, masses and energy levels of ⁶⁰Fe and ¹²⁰Cd were measured. The ⁷Be particles were detected in a single wire proportional counter backed by a plastic scintillator in the focal plane of an Enge spectrometer to ensure adequate particle identification. Total energy resolution as small as 140 keV full width at half maximum was obtained, although in most cases the target thickness limited the energy resolution to larger values. Differential cross sections as low as 20 nb/sr were measured. The finite range programs LOLA and LOLITA were used to calculate differential cross sections for comparison to data, assuming the reaction to proceed by a direct α-transfer. The spectroscopic factors which were extracted show a marked decrease with increasing atomic mass number, implying a decrease in surface α-clustering for heavier nuclei.     

Two particle correlations in the central region of pp and π−p interactions at 100–300 GeV/c

Significant positive correlations are seen for all charge combinations of pion pairs with small rapidity separation. Joint rapidity-azimuthal correlations show that this positive correlation occurs when like (unlike) pions are produced with small (large) separation in azimuth.     

Semi-inclusive π− cross sections in pp interactions up to 300 GeV/c

Semi-inclusive π^? cross sections in 200 and 300 GeV/c pp interactions are presented and compared with lower energy data. In the target fragmentation region the data are compared to the hypothesis of semi-inclusive KNO scaling. The energy and charge multiplicity dependences of the semi-inclusive cross sections in the central region are studied and a simple parametrization of the semi-inclusive density function is described.