118,723 research outputs found
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Tuber sinomacrosporum S. P. Wan, & F. Q. Yu 2023, sp. nov.
No full textTuber sinomacrosporum S. P. Wan, & F. Q. Yu, sp. nov. (FIGURE 2) MycoBank: 846502 Typification: CHINA. Yunnan Province, Dali City (25° 38′ N , 100° 68′ E), in humic soil under a pure Pinus forest, at about 2090 m, 26 December 2020, wsp1043-8, YNAU016 (GenBank ITS number = OK625303). Diagnosis: Tuber sinomacrosporum is characterized by the brownish-red ascoma, mostly 1(2)-spored asci, large and ellipsoid ascospores. Etymology: referring to a Chinese species have large spores. Description: Ascoma 2.2 × 1.35 cm in diam, oval-shaped or irregular, light brown, partial brown to brownishred when fresh, becoming brownish-red when dried, surface partially covered with yellow tomentose. Odor pleasant. Peridium 108.0–148.0 μm thick, one layer, prosenchymatous, composed of yellowish to transparent cells and interwoven hyphae, cells (1.0–)2.2–5.7(–7.8) × (1.0–)1.7–4.5(–5.4) μm, hyphae 1.3–2.8 μm in diam. Gleba solid, blackish at maturity, marbled with different whitish to greyish veins continuous with the peridium; composed of hyaline, interwoven, thin-walled hyphae, 0.7–2.4 μm broad at the septa, the cells subglobose to globose, 1.1–7.3(– 10.5) × 0.9–5.7(–8.6) μm. Asci 114.0–143.0(–158.0) × 86.0–117.0(–124.0) μm, ellipsoid, rarely pyriform or irregular, hyaline, sessile or with a short or tall stalk 7.5–49.0 μm, 1-spored, rarely 2-spored. Ascospores ellipsoid, sometimes oblong elliptical and broadly ellipsoid, hyaline when young, becoming brownish-red to brown at maturity; excluding alveolar ornamentation, in 1-spored asci (80.0–)89.0–105.0(–109.0) × (55.0–)61.0–76.0(–78.0) μm (Q = 1.32–1.53, Q m = 1.43 ± 0.08) (n = 120), in 2-spored (51.0–)55.0–78.0(–84.0) × (32.0–)37.0–55.0(–57.0) μm (Q = 1.25–1.65, Q m = 1.4 ± 0.16) (n = 30). Ornamented with alveolate reticulum, 2–6 μm deep, constituted of irregularly polygonal meshes, reticulum with 3–7 meshes along the spore length and 3–7 across. Distribution and habitat: Hypogeous, in soil under pure stand of Pinus forest in Yunnan Province, China. Known only from China.Published as part of Wan, Shan-Ping, Liu, Wei, Cui, Meng-Jin, Wang, Rui, Wang, Yu-Yun, Liu, Mei-Ju, Wang, Rui- Xue, Yu, Cheng-Jin & Yu, Fu-Qiang, 2023, Morphological and molecular evidence support a new truffle, Tuber sinomacrosporum, in Macrosporum group, pp. 283-291 in Phytotaxa 591 (4) on pages 286-288, DOI: 10.11646/phytotaxa.591.4.5, http://zenodo.org/record/783557
S-Band Class-C-F Power Amplifier with 2nd Harmonic Control at the Input
No full textPower amplifiers (PAs) are the most power-consuming devices in a transmitter. Their performance in efficiency is crucial to the efficiency of the whole system. Therefore, the issue of high efficiency PA has remained hot over the years. This paper presents an approach to design an S-band single stage class-F PA biased in class-C condition. Through the manipulation of the 2nd harmonic at the input, shaping the voltage waveform at the gate node, a class-F PA with proper output matching network (OMN) is realized. The proposed class-C-F PA achieved 60% drain efficiency (DE) and 36.3 dBm of output power around the 3 dB compression point. The methodology of taking the input non-linearity into consideration is also presented. Its feasibility has been verified through both the design and measurements
APC/C and SCFcyclin F Constitute a Reciprocal Feedback Circuit Controlling S-Phase Entry
No full textSummaryThe anaphase promoting complex/cyclosome (APC/C) is an ubiquitin ligase and core component of the cell-cycle oscillator. During G1 phase, APC/C binds to its substrate receptor Cdh1 and APC/CCdh1 plays an important role in restricting S-phase entry and maintaining genome integrity. We describe a reciprocal feedback circuit between APC/C and a second ubiquitin ligase, the SCF (Skp1-Cul1-F box). We show that cyclin F, a cell-cycle-regulated substrate receptor (F-box protein) for the SCF, is targeted for degradation by APC/C. Furthermore, we establish that Cdh1 is itself a substrate of SCFcyclin F. Cyclin F loss impairs Cdh1 degradation and delays S-phase entry, and this delay is reversed by simultaneous removal of Cdh1. These data indicate that the coordinated, temporal ordering of cyclin F and Cdh1 degradation, organized in a double-negative feedback loop, represents a fundamental aspect of cell-cycle control. This mutual antagonism could be a feature of other oscillating systems
Controlled oxidation of hydrocarbons by the membrane-bound methane monooxygenase: The case for a tricopper cluster
No full textS-F and S-D binding sites in the ribosome.
No full text(A, B) Location of the S-F and S-D binding sites in the A. baumannii 70S ribosome with P-site tRNA, respectively. (C, D) Hydrogen-bonding interactions between the streptolidine moieties of S-F and S-D and C1054 of the 16S rRNA, respectively (E, F) Electrostatic interactions of the S-F and S-D 12-carbamoylated gulosamine moiety with A1196, respectively. (G, H) Electrostatic interactions between β-amino of the β-lysine and the O2’ atoms of C1054 and U1052. Throughout the figure, the 50S is blue, 30S is yellow, S-F is gray sticks, S-D is green sticks, and highlighted residues are cyan. The cryo-EM densities corresponding to the 2 terminal β-lysine moieties of S-D were very weak, indicating that these 2 lysine moieties are flexible. We therefore did not include these 2 terminal β-lysine moieties in panels D, F, and H. cryo-EM, cryo-electron microscopy; S-D, streptothricin D; S-F, streptothricin-F.</p
S-F cryo-EM processing workflow.
No full textThe streptothricin natural product mixture (also known as nourseothricin) was discovered in the early 1940s, generating intense initial interest because of excellent gram-negative activity. Here, we establish the activity spectrum of nourseothricin and its main components, streptothricin F (S-F, 1 lysine) and streptothricin D (S-D, 3 lysines), purified to homogeneity, against highly drug-resistant, carbapenem-resistant Enterobacterales (CRE) and Acinetobacter baumannii. For CRE, the MIC50 and MIC90 for S-F and S-D were 2 and 4 μM, and 0.25 and 0.5 μM, respectively. S-F and nourseothricin showed rapid, bactericidal activity. S-F and S-D both showed approximately 40-fold greater selectivity for prokaryotic than eukaryotic ribosomes in in vitro translation assays. In vivo, delayed renal toxicity occurred at >10-fold higher doses of S-F compared with S-D. Substantial treatment effect of S-F in the murine thigh model was observed against the otherwise pandrug-resistant, NDM-1-expressing Klebsiella pneumoniae Nevada strain with minimal or no toxicity. Cryo-EM characterization of S-F bound to the A. baumannii 70S ribosome defines extensive hydrogen bonding of the S-F steptolidine moiety, as a guanine mimetic, to the 16S rRNA C1054 nucleobase (Escherichia coli numbering) in helix 34, and the carbamoylated gulosamine moiety of S-F with A1196, explaining the high-level resistance conferred by corresponding mutations at the residues identified in single rrn operon E. coli. Structural analysis suggests that S-F probes the A-decoding site, which potentially may account for its miscoding activity. Based on unique and promising activity, we suggest that the streptothricin scaffold deserves further preclinical exploration as a potential therapeutic for drug-resistant, gram-negative pathogens.</div
Energy conversion of X-ray, ultraviolet and infrared radiation in Gd2O3 crystals doped with Er3+ ions
No full textSpectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.0 eV, PL excitation spectra (2.8-5.8 eV), PL decay kinetics were measured in Gd2O3 crystals doped both with Er3+ and Zn2+ ions. Synchrotron radiation (VEPP-3 storage ring, Novosibirsk, Russia) were used for XRL measurements. PL spectra were studied at room temperature and T= 88 K under excitation with energy Eexc: a) in fundamental absorption region (Eexc≥Eg); b) in intracenter excitation region (Eexc<Eg); c) in infrared region (Eexc<<Eg) with using laser 980 nm diode as exciting photons (up-conversion processes). The probability of radiative transitions from excited states of the impurity center depends on Eexc. The photoluminescence efficiency in Gd2O3 doped with both Er3+ and Zn2+ ions in the green region decreases, 4F9/2→4I15/2 transitions dominate in the red region both in XRL and PL spectra. This effect is also clearly manifested in the spectra of anti-Stokes luminescence. Energy transfer between the excited Er3+ states of the impurity center and the crystal lattice defect is observed. Decrease of the lifetime of 4S3/2 excited state in Gd2O3:Er3+ + Zn2+ from 120 to 10 μs is observed. This fact indicated s a nonradiative energy transfer between impurity center and defect. Otherwise, the defect concentration variation (by means of doping with heterovalent ions) provides the ability to control the energy conversion efficiency as well as the phosphorus color. © 2017 Author(s).This work was partially supported by the Ministry of Education and Science of the Russian Federation (Government task No. 3.1485.2017/4.6 and basic part of the government mandate, project No. 3.8302.2017/8.9). One of the authors (PVA) thanks Dr. S. Omelkov for their help in PL time-resolved experiments
Precise measurement of the f(s)/f(d) ratio of fragmentation fractions and of B-s(0) decay branching fractions
No full textThe ratio of the B-s(0) and B-0 fragmentation fractions, f(s)/f(d), in proton-proton collisions at the LHC, is obtained as a function of B-meson transverse momentum and collision center-of-mass energy from the combined analysis of different B-decay channels measured by the LHCb experiment. The results are described by a linear function of the meson transverse momentum or with a function inspired by Tsallis statistics. Precise measurements of the branching fractions of the B-s(0) -> J/psi phi and B-s(0)-> D-s(-)pi(+) decays are performed, reducing their uncertainty by about a factor of 2 with respect to previous world averages. Numerous B-s(0) decay branching fractions, measured at the LHCb experiment, are also updated using the new values of f(s)/f(d) and branching fractions of normalization channels. These results reduce a major source of systematic uncertainty in several searches for new physics performed through measurements of B-s(0) branching fractions
Measurement off f(s)/f(u) Variation with Proton-Proton Collision Energy and B-Meson Kinematics
No full textThe ratio of the B-s(0) and B+ fragmentation fractions f(s) and f(u) is studied with B-s(0) -> J/psi phi and B+ -> J/psi K+ decays using data collected by the LHCb experiment in proton-proton collisions at 7, 8, and 13 TeV center-of-mass energies. The analysis is performed in bins of B-meson momentum, longitudinal momentum, transverse momentum, pseudorapidity, and rapidity. The fragmentation-fraction ratio f(s)/f(u) is observed to depend on the B-meson transverse momentum with a significance of 6.0 sigma. This dependency is driven by the 13 TeV sample (8.7 sigma), while the results for the other collision energies are not significant when considered separately. Furthermore, the results show a 4.8 sigma evidence for an increase of f(s)/f(u) as a function of collision energy.LPH
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