Observation of the decay B+/--->pi+/-pi0, study of B+/--->K+/-pi0, and search for B0-->pi0pi0

We present results for the branching fractions and charge asymmetries in B+/--->h(+/-)pi(0) (where h(+/-)=pi(+/-),K+/-) and a search for the decay B0-->pi(0)pi(0) using a sample of approximately 88 x 10(6) BBmacr; pairs collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure B(B+/--->pi(+/-)pi(0))=(5.5(+1.0)(-0.9)+/-0.6)x10(-6), where the first error is statistical and the second is systematic. The B+/--->pi(+/-)pi(0) signal has a significance of 7.7sigma including systematic uncertainties. We simultaneously measure the K+/-pi(0) branching fraction to be B(B+/--->K+/-pi(0))=(12.8(+1.2)(-1.1)+/-1.0)x10(-6). The charge asymmetries are Api(+/-)(pi(0))=-0.03(+0.18)(-0.17)+/-0.02 and AK+/-(pi(0))=-0.09+/-0.09+/-0.01. We place a 90% confidence-level upper limit on the branching fraction B(B0-->pi(0)pi(0)) of 3.6 x 10(-6).     

Evidence for the rare decay B-->K*l+l- and measurement of the B-->Kl+l- branching fraction

We present evidence for the flavor-changing neutral current decay B-->K*l+l- and a measurement of the branching fraction for the related process B-->K l+l-, where l+l- is either an epsilon+epsilon- or a mu+mu- pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123 x 10(6) Upsilon(4S)-->B(-)B decays collected with the BABAR detector at the SLAC PEP-II epsilon+epsilon- storage ring. Averaging over K(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl+l-)=(0.65(+0.14)(-0.13)+/-0.04)x10(-6) and B(B-->K*l+l-)=(0.88(+0.33)(-0.29)+/-0.10)x10(-6), where the uncertainties are statistical and systematic, respectively. The significance of the B-->Kl+l- signal is over 8sigma, while for B-->K*l+l- it is 3.3sigma.     

Structure of extremely nanosized and confined In-O species in ordered porous materials

Perturbed-angular correlation, x-ray absorption, and small-angle x-ray scattering spectroscopies were suitably combined to elucidate the local structure of highly diluted and dispersed InOx species confined in the porous of the ZSM5 zeolite. This novel approach allow us to determined the structure of extremely nanosized In-O species exchanged inside the 10-atom-ring channel of the zeolite, and to quantify the amount of In2O3 crystallites deposited onto the external zeolite surface.     

Measurements of CP-violating asymmetries and branching fractions in B meson decays to eta'K

We present measurements of the branching fractions of the decays B+-->eta'K+ and B0-->eta'K0. For B0-->eta(')K(0)(S) we also measure the time-dependent CP-violation parameters S eta'(K(0)(S)) and C eta'(K(0)(S)), and for B+-->eta'K+ the time-integrated charge asymmetry A(ch). The data sample corresponds to 88.9 x 10(6) BB pairs produced by e(+)e(-) annihilation at the Upsilon(4S). The results are B(B+-->eta'K+)=(76.9+/-3.5+/-4.4) x 10(-6), B(B0-->eta'K0)=(60.6+/-5.6+/-4.6) x 10(-6), S eta'(K(0)(S))=0.02+/-0.34+/-0.03, C eta'(K(0)(S))=0.10+/-0.22+/-0.04, and A(ch)=0.037+/-0.045+/-0.011.     

Search for D0-D(-)0 mixing and a measurement of the doubly Cabibbo-suppressed decay rate in D0-->Kpi decays

We present results of a search for D0-D(-)0 mixing and a measurement of R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays, using D0-->K+pi- decays from 57.1 fb(-1) of data collected near sqrt[s]=10.6 GeV with the BABAR detector at the PEP-II collider. At the 95% confidence level, allowing for CP violation, we find the mixing parameters x('2)<0.0022 and -0.056相似文献   

Molecular tectonics: infinite cationic double stranded helical coordination networks

Upon crystallisation of two bismonodentate tectons based on two pyridine units, interconnected at the meta position by a tetra- or hexa-ethylene glycol fragment and Ag+ cation, double stranded helical infinite coordination networks were formed and structurally characterised. The cationic double helical architectures obtained may be regarded as analogues of DNA in terms of topology.     

Energetic Silver Salts with 5-Aminotetrazole Ligands

Methylation of 5-amino-1H-tetrazole ( 1 ) gives 1-methyl-5-amino-1H-tetrazole ( 2 ) and 2-methyl-5-amino-1H-tetrazole ( 3 ). A new family of energetic silver complexes based on ligands 1 , 2 and 3 with perchlorate and nitrate anions ( 10 – 15 ) were synthesized and characterized by using IR, Raman, and NMR (¹H, ¹³C, ¹⁴N, and ³⁵Cl NMR) spectroscopy, elemental analysis, and mass spectrometry. The crystal structures of the compounds were determined where possible and reveal interesting structural details that are discussed herein. Additionally, differential scanning calorimetry was used to assess the thermal stability of the new salts, which showed excellent thermal stabilities at temperatures up to and above 225 °C. Standard tests were also used to assess the sensitivity of the materials towards impact and friction. All the silver complexes showed increased sensitivity values in comparison with analogous protonated 5-amino-1H-tetrazolium perchlorate and nitrate salts. Some of these materials have sensitivity values that are comparable to commonly used primary explosives and all of them either deflagrate ( 12 – 14 ) or detonate loudly ( 10 and 11 ) on contact with an open flame. Lastly, nitrate salt 11 is easily initiated by thermal shock. It shows reasonably low sensitivity in comparison with other silver salts (e.g., silver azide or silver fulminate), which makes handling it much less hazardous. Compound 11 also has good thermal stability, decomposing at ≈300 °C, and shows interesting properties as a more environmentally benign alternative to lead(II) diazide in initiation devices for civil and military applications.     

Gas chromatographic technique for determination of Irgafos 168 in polyolefin samples after conversion to the related phenolic compound by saponification

A gas chromatographic technique is reported for the determination of a secondary antioxidant, Irgafos 168, in polymeric samples. Irgafos 168 [tris(2,4-di-tert-butyl phenyl)phosphite] is extracted by dissolution/precipitation, saponified to 2,4-di-tert-butyl phenol by refluxing in the presence of methanolic potassium hydroxide, and determined by gas chromatography-flame ionization detection. The method’s repeatability is good, and the relative standard deviation is 7.5% (between runs) and 15.5% (between days). This method was applied to the determination of Irgafos 168 in commercial polymers, and the obtained results were in relatively good agreement with those obtained by the previously reported spectrophotometric method. Correspondence: Mir Ali Farajzadeh, Department of Chemistry, Faculty of Science, Urmia University, Urmia, Iran     

Kinetics of the thermal isomerization of cis-methylcyclopropane carboxylic acid

The gas-phase thermal decomposition of cis-2-methylcyclopropane carboxylic acid was investigated in the temperature range 692–753 K and pressure between 10 and 70 Torr. Arrhenius parameters were determined for homogeneous, unimolecular formation of the isomeric products and for the overall loss-rate of the reactant. The determined values are in accordance with the Arrhenius parameters that were reported previously for the thermal unimolecular reactions of cyclopropane and other substituted cyclopropanes. The formation of isomeric products and the observed Arrhenius parameters are consistent with a biradical mechanism. The effect of surface on the reaction was studied at 732 K using the packed reaction vessel. It was observed that the rate of production of all isomeric products and the total loss of cis-2-methylcyclopropane carboxylic acid were not affected by increasing surface to volume ratio.