Liquid chromatography--multiple tandem mass spectrometry for the determination of ten azaspiracids, including hydroxyl analogues in shellfish

Azaspiracids (AZAs) are a group of polyether toxins that cause food poisoning in humans. These toxins, produced by marine dinoflagellates, accumulate in filter-feeding shellfish, especially mussels. Sensitive liquid chromatography-electrospray ionisation mass spectrometry (LC-ESI-MS(n)) methods have been developed for the determination of the major AZAs and their hydroxyl analogues. These methods, utilising both chromatographic and mass resolution, were applied for the determination of 10 AZAs in mussels (Mytilus edulis). An optimised isocratic reversed phase method (3 microm Luna-2 C18 column) separated 10 azaspiracids using acetonitrile/water (46:54, v/v) containing 0.05% trifluoroacetic acid (TFA) and 0.004% ammonium acetate in 55 min. Analyte determination using MS3 involved trapping and fragmentation of the [M + H]+ and [M + H - H2O]+ ions with detection of the [M + H - 2H2O]+ ion for each AZA. Linear calibrations were obtained for AZA1, using spiked shellfish extracts, in the range 0.05-1.00 microg/ml (r2 = 0.997) with a detection limit of 5 pg (signal : noise = 3). The major fragmentation pathways in hydroxylated azaspiracids were elucidated using hydrogen/deuterium (H/D) exchange experiments. An LC-MS3 method was developed using unique parent ions and product ions, [M + H - H2O - CgH10O2R1R3]+, that involved fragmentation of the A-ring. This facilitated the discrimination between 10 azapiracids, AZA1-10. Thus, this rapid LC-MS3 method did not require complete chromatographic resolution and the run-time of 7 min had detection limits better than 20 pg for each toxin.     

Evidence for B0 s-->phiphi decay and measurements of branching ratio and A(CP) for B+ -->phiK+

We present the first evidence of charmless decays of the B(0)(s) meson, the decay B(0)(s)--> phiphi, and a measurement of the branching ratio BR(B(0)(s)--> phiphi) using 180 pb(-1) of data collected by the CDF II experiment at the Fermilab Tevatron collider. In addition, the BR and direct CP asymmetry for the B+-->phiK+ decay are measured. We obtain BR(B(0)(s)--> phiphi)=[14(+6)(-5)(stat)+/-6(syst)] x 10(-6), BR(B+-->phiK+)=[7.6+/-1.3(stat)+/-0.6(syst)] x 10(-6), and A(CP)(B+-->phiK+)= -0.07+/-0.17(stat)+0.03 / -0.02(syst). Both decays are governed in the standard model by second order (penguin) b-->s(-)ss amplitudes.     

Measurement of the cross section for prompt diphoton production in pp collisions at square root of s=1.96 TeV

We report a measurement of the rate of prompt diphoton production in pp collisions at square root of s=1.96 TeV using a data sample of 207 pb(-1) collected with the upgraded Collider Detector at Fermilab. The background from nonprompt sources is determined using a statistical method based on differences in the electromagnetic showers. The cross section is measured as a function of the diphoton mass, the transverse momentum of the diphoton system, and the azimuthal angle between the two photons and is found to be consistent with perturbative QCD predictions.     

Measurement of partial widths and search for direct CP violation in D0 meson decays to K-K+ and pi-pi+

We present a measurement of relative partial widths and decay rate CP asymmetries in K-K+ and pi(-)pi(+) decays of D0 mesons produced in pp collisions at sqrt[s]=1.96 TeV. We use a sample of 2x10(5) D(*+)-->D0pi(+) (and charge conjugate) decays with the D0 decaying to K-pi(+), K-K+, and pi(-)pi(+), corresponding to 123 pb(-1) of data collected by the Collider Detector at Fermilab II experiment at the Fermilab Tevatron collider. No significant direct CP violation is observed. We measure Gamma(D0-->K-K+)/Gamma(D0-->K-pi(+))=0.0992+/-0.0011+/-0.0012, Gamma(D0-->pi(-)pi(+))/Gamma(D0-->K-pi(+))=0.035 94+/-0.000 54+/-0.000 40, A(CP)(K-K+)=(2.0+/-1.2+/-0.6)%, and A(CP)(pi(-)pi(+))=(1.0+/-1.3+/-0.6)%, where, in all cases, the first uncertainty is statistical and the second is systematic.     

Derivations, isomorphisms, and second cohomology of generalized Witt algebras

Generalized Witt algebras, over a field of characteristic , were defined by Kawamoto about 12 years ago. Using different notations from Kawamoto's, we give an essentially equivalent definition of generalized Witt algebras over , where the ingredients are an abelian group , a vector space over , and a map which is linear in the first variable and additive in the second one. In this paper, the derivations of any generalized Witt algebra
, with the right kernel of being , are explicitly described; the isomorphisms between any two simple generalized Witt algebras are completely determined; and the second cohomology group for any simple generalized Witt algebra is computed. The derivations, the automorphisms and the second cohomology groups of some special generalized Witt algebras have been studied by several other authors as indicated in the references.

     

From graceful labellings of paths to cyclic solutions of the Oberwolfach problem

Constraints are given on graceful labellings for paths that allow them to be used to construct cyclic solutions to the Oberwolfach Problem. We give examples of graceful labellings meeting these constraints and hence, infinitely many new families of cyclic solutions can be constructed.