124 research outputs found
A Novel Lipase from Streptomyces exfoliatus DSMZ 41693 for Biotechnological Applications
Genome mining of Streptomyces exfoliatus DSMZ 41693 has allowed us to identify four different lipase-encoding sequences, and one of them (SeLipC) has been successfully cloned and extracellularly expressed using Rhodococcus sp. T104 as a host. SeLipC was purified by one-step hydrophobic interaction chromatography. The enzyme is a monomeric protein of 27.6 kDa, which belongs to subfamily I.7 of lipolytic enzymes according to its phylogenetic analysis and biochemical characterization. The purified enzyme shows the highest activity at 60 °C and an optimum pH of 8.5, whereas thermal stability is significantly improved when protein concentration is increased, as confirmed by thermal deactivation kinetics, circular dichroism, and differential scanning calorimetry. Enzyme hydrolytic activity using p-nitrophenyl palmitate (pNPP) as substrate can be modulated by different water-miscible organic cosolvents, detergents, and metal ions. Likewise, kinetic parameters for pNPP are: KM = 49.6 ”M, kcat = 57 sâ1, and kcat/KM = 1.15 Ă 106 sâ1·Mâ1. SeLipC is also able to hydrolyze olive oil and degrade several polyester-type polymers such as poly(butylene succinate) (PBS), poly(butylene succinate)-co-(butylene adipate) (PBSA), and poly(Δ-caprolactone) (PCL). Moreover, SeLipC can catalyze the synthesis of different sugar fatty acid esters by transesterification using vinyl laurate as an acyl donor, demonstrating its interest in different biotechnological applications.This research was funded by the Ministerio de Ciencia, InnovaciĂłn y Universidades of Spain, grants RTI2018-096037B-I00, TED2021-131462B-I00, TED2021-130430B-C21, and PDC2022-133817-I00.Peer reviewe
Measurement of forward J/Ï production cross-sections in pp collisions at âs=13 TeV
The production of J/Ï mesons in proton-proton collisions at a centre-of-mass energy of âs=13 TeV is studied with the LHCb detector. Cross-section measurements are performed as a function of the transverse momentum p T and the rapidity y of the J/Ï meson in the region p T < 14 GeV/c and 2.0 < y < 4.5, for both prompt J/Ï mesons and J/Ï mesons from b-hadron decays. The production cross-sections integrated over the kinematic coverage are 15.30 ± 0.03 ± 0.86 ÎŒb for prompt J/Ï and 2.34 ± 0.01 ± 0.13 ÎŒb for J/Ï from b-hadron decays, assuming zero polarization of the J/Ï meson. The first uncertainties are statistical and the second systematic. The cross-section reported for J/Ï mesons from b-hadron decays is used to extrapolate to a total bb cross-section. The ratios of the cross-sections with respect to âs=8 TeV are also determinedS
Measurement of Ï production in pp collisions at âs=13 TeV
The production cross-sections of Ï(1S), Ï(2S) and Ï(3S) mesons in proton-proton collisions at âs=13 TeV are measured with a data sample corresponding to an integrated luminosity of 277 ± 11 pbâ1 recorded by the LHCb experiment in 2015. The Ï mesons are reconstructed in the decay mode Ï â ÎŒ+ÎŒâ. The differential production cross-sections times the dimuon branching fractions are measured as a function of the Ï transverse momentum, pT, and rapidity, y, over the range 0 < pT < 30 GeV/c and 2.0 < y < 4.5. The ratios of the cross-sections with respect to the LHCb measurement at sâ=8 TeV are also determined. The measurements are compared with theoretical predictions based on NRQCD.S
Measurement of the CKM angle Îł using B± â DK± with DâââK0SÏ+Ïâ,âK0SK+Kâ decays
A binned Dalitz plot analysis of B± â DK± decays, with DâââK 0SÏ+ÏââandâDâââK 0SK+Kâ, is used to perform a measurement of the CP-violating observables x± and y±, which are sensitive to the Cabibbo-Kobayashi-Maskawa angle Îł. The analysis is performed without assuming any D decay model, through the use of information on the strong-phase variation over the Dalitz plot from the CLEO collaboration. Using a sample of proton-proton collision data collected with the LHCb experiment in 2015 and 2016, and corresponding to an integrated luminosity of 2.0 fbâ1, the values of the CP violation parameters are found to be xâ = (9.0 ± 1.7 ± 0.7 ± 0.4) Ă 10â2, yâ = (2.1 ± 2.2 ± 0.5 ± 1.1) Ă 10â2, x+ = (â7.7 ± 1.9 ± 0.7 ± 0.4) Ă 10â2, and y+ = (â1.0 ± 1.9 ± 0.4 ± 0.9) Ă 10â2. The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty (on the strong-phase measurements. These values are used to obtain Îłâ=â(87 +â11ââ12)â,ârBâ=â0.086 +â0.013ââ0.014, and ÎŽB = (101±11)°, where rB is the ratio between the suppressed and favoured B-decay amplitudes and ÎŽB is the corresponding strong-interaction phase difference. This measurement is combined with the result obtained using 2011 and 2012 data collected with the LHCb experiment, to give Îłâ=â(80 +â10ââ9)â, rB = 0.080 ± 0.011, and ÎŽB = (110 ± 10)°.S
Evidence for the decay B0SâKÂŻâ0ÎŒ+ÎŒâ
A search for the decay B0SâKÂŻâ0ÎŒ+ÎŒâ is presented using data sets corresponding to 1.0, 2.0 and 1.6 fbâ1 of integrated luminosity collected during pp collisions with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, respectively. An excess is found over the background-only hypothesis with a significance of 3.4 standard deviations. The branching fraction of the B0SâKÂŻâ0ÎŒ+ÎŒâ decay is determined to be B(B0sâKÂŻâ0ÎŒ+ÎŒâ)=[2.9±1.0(stat)±0.2(syst)±0.3(norm)]Ă10â8, where the first and second uncertainties are statistical and systematic, respectively. The third uncertainty is due to limited knowledge of external parameters used to normalise the branching fraction measurement.S
Measurement of D ±s production asymmetry in pp collisions at âs=7 and 8 TeV
The inclusive D ±s production asymmetry is measured in pp collisions collected by the LHCb experiment at centre-of-mass energies of âs=7 and 8 TeV. Promptly produced D ±s mesons are used, which decay as D ±sâââÏϱ, with ÏâââK+Kâ. The measurement is performed in bins of transverse momentum, pT, and rapidity, y, covering the range 2.5 < pT < 25.0 GeV/c and 2.0 < y < 4.5. No kinematic dependence is observed. Evidence of nonzero D ±s production asymmetry is found with a significance of 3.3 standard deviations.S
Central exclusive production of J/Ï and Ï(2S) mesons in pp collisions at âs=13 TeV
Measurements are reported of the central exclusive production of J/Ï and Ï(2S) mesons in pp collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range 2.0 < η < 4.5, are measured to be
ÏJ/ÏâÎŒ+ÎŒâ=435±18±11±17 pbÏÏ(2S)âÎŒ+ÎŒâ=11.1±1.1±0.3±0.4 pb.
The first uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross-sections are also measured differentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross-sections are derived and compared to previous experiments, and a deviation from a pure power-law extrapolation of lower energy data is observed.S
Observation of the decay BÂŻ0sâÏc2K+Kâ in the Ï mass region
The BÂŻ0sâÏc2K+Kâ decay mode is observed and its branching fraction relative to the corresponding Ïc1 decay mode, in a ±15 MeV/c2 window around the Ï mass, is found to be
B(BÂŻ0sâÏc2K+Kâ)B(BÂŻ0sâÏc1K+Kâ)=(17.1±3.1±0.4±0.9)%,
where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the branching fractions of radiative Ïc decays. The decay mode BÂŻ0sâÏc1K+Kâ allows the B0s mass to be measured as
m(B0s)=5366.83±0.25±0.27 MeV/c2,
where the first uncertainty is statistical and the second systematic. A combination of this result with other LHCb determinations of the B 0s mass is made.S
Evidence for an ηc(1S)Ïâ resonance in B0 â ηc(1S)K+Ïâ decays
A Dalitz plot analysis of B0 â ηc(1S)K +Ïâ
decays is performed using data samples of pp collisions collected with the LHCb detector at centre-of-mass energies
of âs = 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 4.7 fbâ1. A satisfactory description of
the data is obtained when including a contribution representing an exotic ηc(1S)Ïâ resonant state. The significance
of this exotic resonance is more than three standard deviations, while its mass and width are 4096 ± 20 +18
â22 MeV and
152±58 +60
â35 MeV, respectively. The spin-parity assignments
J P = 0+ and J P = 1â are both consistent with the data. In
addition, the first measurement of the B0 â ηc(1S)K +Ïâ
branching fraction is performed and gives
B(B0â ηc(1S)K +Ïâ) = (5.73 ± 0.24 ± 0.13 ± 0.66) Ă 10â4,
where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external
branching fractionsS
Studies of the resonance structure in D0âKâϱϱÏâ decays
Amplitude models are constructed to describe
the resonance structure of D0 â Kâ
Ï
+
Ï
+
Ï
â and D0 â
K+
Ï
â
Ï
â
Ï
+ decays using pp collision data collected at
centre-of-mass energies of 7 and 8 TeV with the LHCb
experiment, corresponding to an integrated luminosity of
3.0 f bâ1. The largest contributions to both decay amplitudes
are found to come from axial resonances, with decay modes
D0 â a1(1260)
+Kâ and D0 â K1(1270/1400)
+
Ï
â
being prominent in D0 â Kâ
Ï
+
Ï
+
Ï
â and D0 â
K+
Ï
â
Ï
â
Ï
+, respectively. Precise measurements of the
lineshape parameters and couplings of the a1(1260)
+,
K1(1270)
â and K(1460)
â resonances are made, and a quasi
model-independent study of the K(1460)
â resonance is performed.
The coherence factor of the decays is calculated from
the amplitude models to be RK3Ï = 0.459 ± 0.010 (stat) ±
0.012 (syst)±0.020 (model), which is consistent with direct
measurements. These models will be useful in future measurements
of the unitary-triangle angle Îł and studies of
charm mixing and CP violationS
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