The efficient transformation of CO
into chemicals and fuels is a key challenge for the decarbonisation of the synthetic production chain. Formic acid (FA) represents the first product of CO
...hydrogenation and can be a precursor of higher added value products or employed as a hydrogen storage vector. Bases are typically required to overcome thermodynamic barriers in the synthesis of FA, generating waste and requiring post-processing of the formate salts. The employment of buffers can overcome these limitations, but their catalytic performance has so far been modest. Here, we present a methodology utilising IL as buffers to catalytically transform CO
into FA with very high efficiency and comparable performance to the base-assisted systems. The combination of multifunctional basic ionic liquids and catalyst design enables the synthesis of FA with very high catalytic efficiency in TONs of >8*10
and TOFs > 2.1*10
h
.
Understanding the molecular mechanism of proton conduction is crucial for the design of new materials with improved conductivity. Quasi-elastic neutron scattering (QENS) has been used to probe the ...mechanism of proton diffusion within a new phosphonate-based metal–organic framework (MOF) material, MFM-500(Ni). QENS suggests that the proton conductivity (4.5 × 10–4 S/cm at 98% relative humidity and 25 °C) of MFM-500(Ni) is mediated by intrinsic “free diffusion inside a sphere”, representing the first example of such a mechanism observed in MOFs.
Abstract The resonant substructure of D 0 → π+π−π+π− decays is studied using data collected by the CLEO-c detector. An amplitude analysis is performed in order to disentangle the various intermediate ...state contributions. To limit the model complexity a data driven regularization procedure is applied. The prominent contributions are the decay modes D 0 → a 1(1260)+ π−, D 0 → σ f 0(1370) and D 0 → ρ(770)0 ρ(770)0. The broad resonances a 1(1260)+, π(1300)+ and a 1(1640)+ are studied in detail, including quasi-modelindependent parametrizations of their lineshapes. The mass and width of the a 1(1260)+ meson are determined to be m a1(1260)+ = 1225 ± 9 (stat) ± 17 (syst) ± 10 (model) MeV/c 2 and Γa1(1260)+ = 430 ± 24 (stat) ± 25 (syst) ± 18 (model) MeV. The amplitude model of D 0 → K + K −π+π− decays obtained from CLEO II.V, CLEO III, and CLEO-c data is revisited with improved lineshape parametrizations. The largest components are the decay modes D 0 → ϕ(1020)ρ(770)0, D 0 → K 1(1270)+ K − and D 0 → K(1400)+ K −. The fractional CP -even content of the decay D 0 → π+π−π+π− is calculated from the amplitude model to be F + 4π = 72.9 ± 0.9(stat) ± 1.5(syst) ± 1.0(model) %, consistent with that obtained from a previous model-independent measurement. For D 0 → K + K −π+π− decays, the CP -even fraction is measured for the first time and found to be F + KKππ = 75.3 ± 1.8 (stat) ± 3.3 (syst) ± 3.5 (model) %. The global decay rate asymmetries between D 0 and D ¯ 0 $$ {\overline{D}}^0 $$ decays are measured to be A C P 4 π = + 0.54 ± 1.04 stat ± 0.51 syst % $$ {\mathcal{A}}_{CP}^{4\uppi}=\left+0.54\pm 1.04\ \left(\mathrm{stat}\right)\pm 0.51\ \left(\mathrm{syst}\right)\right\% $$ and A C P KKππ = + 1.84 ± 1.74 stat ± 0.30 syst % $$ {\mathcal{A}}_{CP}^{KK\pi \pi}=\left+1.84\pm 1.74\ \left(\mathrm{stat}\right)\pm 0.30\ \left(\mathrm{syst}\right)\right\% $$ . A search for CP asymmetries in the amplitude components yields no evidence for CP violation in either decay mode.
Selective adsorption of SO2 is realized in a porous metal–organic framework material, and in‐depth structural and spectroscopic investigations using X‐rays, infrared, and neutrons define the ...underlying interactions that cause SO2 to bind more strongly than CO2 and N2.
A narrow pentaquark state, Pc(4312)+, decaying to J/ψp, is discovered with a statistical significance of 7.3σ in a data sample of Λb0→J/ψpK− decays, which is an order of magnitude larger than that ...previously analyzed by the LHCb Collaboration. The Pc(4450)+ pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, Pc(4440)+ and Pc(4457)+, where the statistical significance of this two-peak interpretation is 5.4σ. The proximity of the Σc+D¯0 and Σc+D¯*0 thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.
Three multi-carboxylic acid functionalised ligands have been designed, synthesised and utilised to prepare the new barium-based MOFs, MFM-510, -511, and -512, which show excellent stability to ...water-vapour. MFM-510 and MFM-511 show moderate proton conductivities (2.1 × 10
and 5.1 × 10
S cm
, respectively) at 99% RH and 298 K, attributed to the lack of free protons or hindered proton diffusion within the framework structures. In contrast, MFM-512, which incorporates a pendant carboxylic acid group directed into the pore of the framework, shows a two orders of magnitude enhancement in proton conductivity (2.9 × 10
S cm
). Quasi-elastic neutron scattering (QENS) suggests that the proton dynamics of MFM-512 are mediated by "free diffusion inside a sphere" confirming that incorporation of free carboxylic acid groups within the pores of MOFs is an efficient albeit synthetically challenging strategy to improve proton conductivity.
The ratio of branching fractions R ( D * − ) ≡ B ( B 0 → D * − τ + ν τ ) / B ( B 0 → D * − μ + ν μ ) is measured using a data sample of proton-proton collisions collected with the LHCb detector at ...center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb − 1 . For the first time, R ( D * − ) is determined using the τ -lepton decays with three charged pions in the final state. The B 0 → D * − τ + ν τ yield is normalized to that of the B 0 → D * − π + π − π + mode, providing a measurement of B ( B 0 → D * − τ + ν τ ) / B ( B 0 → D * − π + π − π + ) = 1.97 ± 0.13 ± 0.18 , where the first uncertainty is statistical and the second systematic. The value of B ( B 0 → D * − τ + ν τ ) = ( 1.42 ± 0.094 ± 0.129 ± 0.054 ) % is obtained, where the third uncertainty is due to the limited knowledge of the branching fraction of the normalization mode. Using the well-measured branching fraction of the B 0 → D * − μ + ν μ decay, a value of R ( D * − ) = 0.291 ± 0.019 ± 0.026 ± 0.013 is established, where the third uncertainty is due to the limited knowledge of the branching fractions of the normalization and B 0 → D * − μ + ν μ modes. This measurement is in agreement with the standard model prediction and with previous results.
We report the reversible adsorption of ammonia (NH3) up to 9.9 mmol g–1 in a robust Al-based metal–organic framework, MFM-303(Al), which is functionalized with free carboxylic acid and hydroxyl ...groups. The unique pore environment decorated with these acidic sites results in an exceptional packing density of NH3 at 293 K (0.801 g cm–3) comparable to that of solid NH3 at 193 K (0.817 g cm–3). In situ synchrotron X-ray diffraction and inelastic neutron scattering reveal the critical role of free −COOH and −OH groups in immobilizing NH3 molecules. Breakthrough experiments confirm the excellent performance of MFM-303(Al) for the capture of NH3 at low concentrations under both dry and wet conditions.
Observation of the Doubly Charmed Baryon Ξ++cc Alfonso Albero, Alejandro; Badalov, Alexey; Calvo Gómez, Míriam ...
Physical review letters,
09/2017, Letnik:
119, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A highly significant structure is observed in the Λc+K-π+π+ mass spectrum, where the Λc+ baryon is reconstructed in the decay mode p K-π+. The structure is consistent with originating from a weakly ...decaying particle, identified as the doubly charmed baryon Ξcc ++. The difference between the masses of the Ξcc ++ and Λc+ states is measured to be 1334.94 ±0.72 (stat.) ±0.27 (syst. ) MeV /c2 , and the Ξcc ++ mass is then determined to be 3621.40 ±0.72 (stat.) ±0.27 (syst. ) ±0.14 (Λc+) MeV /c2 , where the last uncertainty is due to the limited knowledge of the Λc+ mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb-1, and confirmed in an additional sample of data collected at 8 TeV.
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