12 research outputs found
Styrene, an Unpalatable Substrate with Complex Regulatory Networks
Styrene, a volatile organic compound (VOC), is an important industrial material involved in the production of plastic, synthetic rubber and resin, insulation and other industrial materials containing molecules such as polystyrene, butadiene-styrene latex, styrene copolymers and unsaturated polyester resins. Styrene exposure may cause contact-based skin inflammation, irritation of eyes, nose and respiratory tract. Neurological effects such as alterations in vision, hearing loss and longer reaction times, have been associated with styrene exposure in the workplace. In addition, styrene oxide may act as an established mutagen and carcinogen (www.epa.gov/chemfact/styre-sd.pdf). It has been reported that, in 2002, 22,323 tons of styrene were released to the environment (82), in spite of the US Clean Air Act mandate on reduction in the volume of allowable styrene emission (www.epa.gov/chemfact/styre-sd.pdf). Among a variety of emerging air pollution technologies, biofiltration is an attractive option for the treatment of VOCs, because it is cost-effective and does not generate secondary contaminants (45). Moreover, microbial biodegradation is the major route for the removal of non-aqueous compounds from soils. Styrene is also naturally present in non polluted environments, since it derives from fungal decarboxylation of cinnamic acid (90). Therefore it is not surprising that microorganisms of different families have been found to be able to degrade this compound (31). The promising results obtained in the removal of styrene from contaminated waste-gases by biofiltration (5, 39, 103) have led to an increasing attention to the regulatory mechanisms underlying styrene degradation, with the aim to improve bioremediation processes. Despite the diffusion in nature of this degradative capability, only few strains, mainly belonging to the Pseudomonas genus, have been characterized (66).
This chapter is focused on the up-to-now discovered regulatory mechanisms underlying the expression of the styrene-catabolism genes. Moreover, open questions on environmental and metabolic constrains that govern styrene degradation are discussed. Biotechnological relevance of styrene-degrading strains in fine chemicals production and bioremediation processes is not examined here. Main topics on these application fields have recently been reviewed by Dobson and co-workers (66)
Energy scan of the cross sections and evidence for the decays into charged bottomonium-like states
Using data collected with the Belle detector in the energy region of the and resonances we measure the cross sections. Their energy dependences show clear and peaks with a small or no non-resonant contribution. We study resonant structure of the transitions and find evidence that they proceed entirely via intermediate charged bottomonium-like states and/or (with current statistics we can not discriminate hypotheses of one or two intermediate states).Using data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, we measure the energy dependence of the e+e-→hb(nP)π+π- (n=1, 2) cross sections from thresholds up to 11.02 GeV. We find clear ϒ(10860) and ϒ(11020) peaks with little or no continuum contribution. We study the resonant substructure of the ϒ(11020)→hb(nP)π+π- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb(10610) and Zb(10650). The relative fraction of these states is loosely constrained by the current data: The hypothesis that only Zb(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb(10650) is produced is not excluded at a significant level.Using data collected with the Belle detector at the KEKB asymmetric-energy collider, we measure the energy dependence of the cross sections from thresholds up to GeV. We find clear and peaks with little or no continuum contribution. We study the resonant substructure of the transitions and find evidence that they proceed entirely via the intermediate isovector states and . The relative fraction of these states is loosely constrained by the current data: the hypothesis that only is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only is produced is not excluded at a significant level
Measurements of branching fraction and asymmetry of the decay at Belle
International audienceWe report the measurement of the branching fraction and asymmetry for the decay. The analysis is performed on a data sample of 711 collected at the resonance with the Belle detector at the KEKB asymmetric-energy collider. We obtain a branching fraction of and an of , where the first uncertainties are statistical and the second are systematic. Hints of peaking structures are also observed in the differential branching fraction as functions of Dalitz variables
Measurement of and with a semileptonic tagging method
We report a measurement of the ratios of branching fractions and , where denotes an electron or a muon. The results are based on a data sample containing events recorded at the resonance with the Belle detector at the KEKB collider. The analysis utilizes a method where the tag-side meson is reconstructed in a semileptonic decay mode, and the signal-side is reconstructed in a purely leptonic decay. The measured values are and , where the first uncertainties are statistical and the second are systematic. These results are in agreement with the Standard Model predictions within and standard deviations, respectively, while their combination agrees with the Standard Model predictions within standard deviations
Test of lepton flavor universality in decays at Belle
We present a measurement of , the ratio of the branching fractions and , for both charged and neutral mesons. The ratio for charged mesons, , is the first measurement ever performed. The analysis is based on a data sample of , containing events, recorded at the resonance with the Belle detector at the KEKB asymmetric-energy collider
Measurement of the polarization in the decay
International audienceWe report the first measurement of the meson polarization in the decay using the full data sample of 772 pairs recorded with the Belle detector at the KEKB electron-positron collider. Our result, , where denotes the meson longitudinal polarization fraction, agrees within about standard deviations of the standard model prediction
Test of lepton flavor universality and search for lepton flavor violation in decays
International audienceWe present measurements of the branching fractions for the decays B → Kμμ and B → Kee, and their ratio (R), using a data sample of 711 fb that contains 772 × 10 events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy ee collider. The ratio R is measured in five bins of dilepton invariant-mass-squared (q): q ∈ (0.1, 4.0), (4.00, 8.12), (1.0, 6.0), (10.2, 12.8) and (> 14.18) GeV/c, along with the whole q region. The R value for q ∈ (1.0, 6.0) GeV/c is ± 0.01. The first and second uncertainties listed are statistical and systematic, respectively. All results for R are consistent with Standard Model predictions. We also measure CP-averaged isospin asymmetries in the same q bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the q ∈ (1.0, 6.0) GeV/c bin in the mode with muon final states. The measured differential branching fractions, /dq, are consistent with theoretical predictions for charged B decays, while the corresponding values are below the expectations for neutral B decays. We have also searched for lepton-flavor-violating B → Kμe decays and set 90% confidence-level upper limits on the branching fraction in the range of 10 for B → Kμe, and B → Kμe modes.[graphic not available: see fulltext