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The loss of C2H2 is a low activation energy dissociation channel for anthracene (C14H10) and acridine (C13H9N) cations. For the latter ion another prominent fragmentation pathway is the loss of HCN. We have studied these two dissociation channels by collision induced dissociation experiments of 50 keV anthracene cations and protonated acridine, both produced by electrospray ionization, in collisions with a neutral xenon target. In addition, we have carried out density functional theory calculations on possible reaction pathways for the loss of C2H2 and HCN. The mass spectra display features of multi-step processes, and for protonated acridine the dominant first step process is the loss of a hydrogen from the N site, which then leads to C2H2/HCN loss from the acridine cation. With our calculations we have identified three pathways for the loss of C2H2 from the anthracene cation, with three different cationic products: 2-ethynylnaphthalene, biphenylene, and acenaphthylene. The third product is the one with the overall lowest dissociation energy barrier. For the acridine cation our calculated pathway for the loss of C2H2 leads to the 3-ethynylquinoline cation, and the loss of HCN leads to the biphenylene cation. Isomerization plays an important role in the formation of the non-ethynyl containing products. All calculated fragmentation pathways should be accessible in the present experiment due to substantial energy deposition in the collisions. [ABSTRACT FROM AUTHOR]

We have studied electron capture induced dissociation of a set of doubly protonated pentapeptides, all composed of one lysine (K) and either four glycine (G) or four alanine (A) residues, as a function of the sequence of these building blocks. Thereby the separation of the two charges, sequestered on the N-terminal amino group and the lysine side chain, is varied. The characteristic cleavage of N-Cα bonds is observed for all peptides over the whole backbone length, with the charge carrying fragments always containing K. The resulting fragmentation patterns are very similar if G is replaced by A. In the case of [XKXXX+2H]2+ (X=A or G), a distinct feature is observed in the distribution of backbone cleavage fragments and the probability for ammonia loss is drastically reduced. This may be due to an isomer with an amide oxygen as protonation site giving rise to the observed increase in breakage at a specific site in the molecule. For the other peptides, a correlation with the distance between amide oxygen and the charge at the lysine side chain has been found. This may be an indication that it is only the contribution from this site to the charge stabilization of the amide π* orbitals which determines relative fragment intensities. For comparison, complexes with two crown ether molecules have been studied as well. The crown ether provides a shielding of the charge and prevents the peptide from folding and internal hydrogen bonding, which leads to a more uniform fragmentation behavior. [ABSTRACT FROM AUTHOR]

We have studied the outcome of collisions between the hydrated nucleotide anion adenosine 5′-monophosphate (AMP) and sodium. Electron capture leads to hydrogen loss as well as water evaporation regardless of the initial number m of water molecules attached to the parent ion (m≤=16). The yield of dianions with microsecond lifetimes increases strongly with m, which is explained from dielectric screening of the two charges by the water nanodroplet. For comparison, collision induced dissociation results in water losses with no or very little damage of the AMP molecule itself [ABSTRACT FROM AUTHOR]

In this paper, we give a detailed description of an electrospray ion source test bench and a single-pass setup for ion fragmentation studies at the Double ElectroStatic Ion Ring ExpEriment infrastructure at Stockholm University. This arrangement allows for collision-induced dissociation experiments at the center-of-mass energies between 10 eV and 1 keV. Charged fragments are analyzed with respect to their kinetic energies (masses) by means of an electrostatic energy analyzer with a wide angular acceptance and adjustable energy resolution. [ABSTRACT FROM AUTHOR]

Thirteen species of lesser known wood inhabiting fungi living on grapevine (Vitis vinifera) and/or in the vicinity of vineyards are presented with respect to systematics, life strategy and symptoms, host range, geographic distribution, transmission and occurrence on Vitis, identification, and diagnosis. Sampling has been performed during a three-year-survey covering nurseries, vineyards, and neighboring fruit trees in the viticultural area of southern Palatinate, Germany. The possible pathogenic significance and the relation to grapevine trunk diseases are discussed. The following species are reported for the first time in Germany: Cadophora luteo-olivacea, C. fastigiata, Collophora paarla, Coniochaeta hoffmannii, Eucasphaeria capensis, Phomopsis cotoneastri, and the Esca-related Phaeoacremonium viticola and P. fraxinopennsylvannicum. Eucasphaeria capensis and Phomopsis cotoneastri are reported for the first time from Vitis worldwide. [ABSTRACT FROM AUTHOR]

We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate 'rings' and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology. [ABSTRACT FROM AUTHOR]

As part of a long-term safety study the bisphosphonate ibandronate was investigated for its effects on bone quality in lumbar vertebrae in rats. Bone area, bone density and mechanical properties were assessed by peripheral quantitative computed tomography (pQCT), dual-energy X-ray absorptiometry (DXA) and compression tests. Female and male groups of Wistar rats received either vehicle or 3, 7 or 15 mg/kg per day of ibandronate over 104 weeks orally by gavage. Compared with the control group, bone mineral density, compressive strength and stiffness were significantly higher in ibandronate-treated animals, whereas no changes occurred in strain or modulus of elasticity. The increase in vertebral body stress was significant in some of the ibandronate-treated groups. The changes in mechanical properties appear to be due mainly to an increase in bone mass. A highly significant correlation was found between bone mineral density measured either by DXA ( r=0.86) or pQCT ( r=0.85) and maximal strength in vertebral bodies (p<0.0001 each). In conclusion, we demonstrated that lifelong administration of doses of ibandronate far in excess of any therapeutically intended dose not only increases bone mass and apparent density, but also maintains or even slightly improves bone quality. Bone mineral density measured either by pQCT or DXA can be used as a predictor for ultimate strength in rat lumbar vertebral bodies after treatment with ibandronate. [ABSTRACT FROM AUTHOR]