Determinants of mortality in patients with cirrhosis and uncontrolled variceal bleeding

BACKGROUND AND AIM: Failure to control oesophago-gastric variceal bleeding (OGVB) and acute-on-chronic liver failure (ACLF) are both important prognostic factors in liver cirrhosis. The aims of this study were to determine whether ACLF and its severity define the risk of death in OGVB and whether insertion of rescue transjugular intrahepatic stent-shunt (TIPSS) improves the survival of patients with failure to control OGVB and ACLF. METHODS: From a prospectively maintained ICU registry, data of 174 consecutive eligible patients with failure to control OGVB between 2005 and 2015, were included. Rescue TIPSS was defined as technically successful TIPSS within 72-hours of presentation with failure to control OGVB. Cox proportional hazards regression analyses were applied to explore the impact of ACLF and TIPSS on survival in failure-to-control OGVB. RESULTS: ACLF patients (n=119) were significantly older, had organ failures and higher white cell count compared with patients with acute decompensation (AD, n=55). Mortality at 42-days and 1-year was significantly higher in ACLF (47.9% and 61.3%) as compared to AD patients (9.1% and 12.7%, p<0.001), whereas there was no difference in the number of endoscopies and transfusion requirements between these groups. TIPSS was inserted in 78 patients [AD: 21 (38.2%); ACLF: 57 (47.8%), p=0.41]. In ACLF, rescue TIPSS insertion was an independent favorable prognostic factor for 42-day mortality. In contrast, rescue TIPSS did not impact on the outcome of AD patients. CONCLUSIONS: This study shows for the first time that in patients with failure to control OGVB, the presence and severity of ACLF determines the risk of 42-day and 1-year mortality. Rescue TIPSS is associated with improved survival of ACLF patients

Host-guest and guest-guest interactions between xylene isomers confined in the MIL-47(V) pore system

The porous MIL-47 material shows a selective adsorption behavior for para-, ortho-, and meta-isomers of xylenes, making the material a serious candidate for separation applications. The origin of the selectivity lies in the differences in interactions (energetic) and confining (entropic). This paper investigates the xylene-framework interactions and the xylene-xylene interactions with quantum mechanical calculations, using a dispersion-corrected density functional and periodic boundary conditions to describe the crystal. First, the strength and geometrical characteristics of the optimal xylene-xylene interactions are quantified by studying the pure and mixed pairs in gas phase. An extended set of initial structures is created and optimized to sample as many relative orientations and distances as possible. Next, the pairs are brought in the pores of MIL-47. The interaction with the terephthalic linkers and other xylenes increases the stacking energy in gas phase (-31.7 kJ/mol per pair) by roughly a factor four in the fully loaded state (-58.3 kJ/mol per xylene). Our decomposition of the adsorption energy shows various trends in the contributing xylene-xylene interactions. The absence of a significant difference in energetics between the isomers indicates that entropic effects must be mainly responsible for the separation behavior

Opening the Gate:Framework Flexibility in ZIF-8 Explored by Experiments and Simulations

ZIF-8 is a zeolitic imidazole-based metal-organic framework with large cavities interconnected by narrow windows. Because the small size of the windows, it allows in principle for molecular sieving of gases such as H-2 and CH4. However, the unexpected adsorption of large molecules on ZIF-8 suggests the existence of structural flexibility. ZIF-8 flexibility is explored in this work combining different experimental techniques with molecular simulation. We show that the ZIF-8 structure is modified by gas adsorption uptake in the same way as it is at a very high pressure (i.e., 14 700 bar) due to a swing effect in the imidazolate linkers, giving access to the porosity. Tuning the flexibility, and so the opening of the small windows, has a further impact on the design of advanced molecular sieving membrane materials for gas separation, adjusting the access of fluids to the porous network.</p

Selective CO₂ capture in metal-organic frameworks with azine-functionalized pores generated by mechanosynthesis

Two new three-dimensional porous Zn(II)-based metal-organic frameworks, containing azine-functionalized pores, have been readily and quickly isolated via mechanosynthesis, by using a nonlinear dicarboxylate and linear N-donor ligands. The use of nonfunctionalized and methyl-functionalized N-donor ligands has led to the formation of frameworks with different topologies and metal-ligand connectivities and therefore different pore sizes and accessible volumes. Despite this, both metal-organic frameworks (MOFs) possess comparable BET surface areas and CO₂ uptakes at 273 and 298 K at 1 bar. The network with narrow and interconnected pores in three dimensions shows greater affinity for CO compared to the network with one-dimensional and relatively large pores-attributable to the more effective interactions with the azine groups

Three-dimensional lanthanide-organic frameworks based on di-, tetra-, and hexameric clusters

Three-dimensional lanthanide-organic frameworks formulated as (CH3)2NH2[Ln(pydc)2] · 1/2H2O [Ln3+ ) Eu3+ (1a) or Er3+ (1b); pydc2- corresponds to the diprotonated residue of 2,5-pyridinedicarboxylic acid (H2pydc)], [Er4(OH)4(pydc)4(H2O)3] ·H2O (2), and [PrIII 2PrIV 1.25O(OH)3(pydc)3] (3) have been isolated from typical solvothermal (1a and 1b in N,N-dimethylformamide - DMF) and hydrothermal (2 and 3) syntheses. Materials were characterized in the solid state using single-crystal X-ray diffraction, thermogravimetric analysis, vibrational spectroscopy (FT-IR and FT-Raman), electron microscopy, and CHN elemental analysis. While synthesis in DMF promotes the formation of centrosymmetric dimeric units, which act as building blocks in the construction of anionic ∞ 3{[Ln(pydc)2]-} frameworks having the channels filled by the charge-balancing (CH3)2NH2 + cations generated in situ by the solvolysis of DMF, the use of water as the solvent medium promotes clustering of the lanthanide centers: structures of 2 and 3 contain instead tetrameric [Er4(μ3-OH)4]8+ and hexameric |Pr6(μ3-O)2(μ3-OH)6| clusters which act as the building blocks of the networks, and are bridged by the H2-xpydcx- residues. It is demonstrated that this modular approach is reflected in the topological nature of the materials inducing 4-, 8-, and 14-connected uninodal networks (the nodes being the centers of gravity of the clusters) with topologies identical to those of diamond (family 1), and framework types bct (for 2) and bcu-x (for 3), respectively. The thermogravimetric studies of compound 3 further reveal a significant weight increase between ambient temperature and 450 °C with this being correlated with the uptake of oxygen from the surrounding environment by the praseodymium oxide inorganic core

Diffusion of Carbon Dioxide and Nitrogen in the Small-Pore Titanium Bis(phosphonate) Metal-Organic Framework MIL-91 (Ti): A Combination of Quasielastic Neutron Scattering Measurements and Molecular Dynamics Simulations

SSCI-VIDE+ATARI+HJOInternational audiencecarbon dioxid

Multifaceted study of the interactions between CPO-27-Ni and polyurethane and their impact on nitric oxide release performance

S.M.V. would like to thank the EPSRC for funding opportunities under grant agreement EP/K005499/1. S.M.V. and D.N.M. would further like to acknowledge the EPSRC Capital for Great Technologies grant (EP/L017008/1) and the EPSRC Strategic Equipment Resource grant (EP/R023751) for funding and supporting electron microscopy facilities at the University of St Andrews. M.J.D. and S.J.W. would like to acknowledge the ProDIA project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 685727.A multifaceted study involving focused ion beam scanning electron microscopy techniques, mechanical analysis, water adsorption measurements, and molecular simulations is employed to rationalize the nitric oxide release performance of polyurethane films containing 5, 10, 20, and 40 wt % of the metal-organic framework (MOF) CPO-27-Ni. The polymer and the MOF are first demonstrated to exhibit excellent compatibility. This is reflected in the even distribution and encapsulation of large wt % MOF loadings throughout the full thickness of the films and by the rather minimal influence of the MOF on the mechanical properties of the polymer at low wt %. The NO release efficiency of the MOF is attenuated by the polymer and found to depend on wt % of MOF loading. The formation of a fully connected network of MOF agglomerates within the films at higher wt % is proposed to contribute to a more complex guest transport in these formulations, resulting in a reduction of NO release efficiency and film ductility. An optimum MOF loading of 10 wt % is identified for maximizing NO release without adversely impacting the polymer properties. Bactericidal efficacy of released NO from the films is demonstrated against Pseudomonas aeruginosa, with a >8 log10 reduction in cell density observed after a contact period of 24 h.Publisher PDFPeer reviewe

Diffusion of H-2, CO2, and Their Mixtures in the Porous Zirconium Based Metal Organic Framework MIL-140A(Zr): Combination of Quasi-Elastic Neutron Scattering Measurements and Molecular Dynamics Simulations

SSCI-VIDE+ATARI+HJOInternational audienceThe diffusivity of H-2 and CO2 in the small pore Zr based metalorganic framework (MOF) MIL-140A(Zr) has been evaluated using a combination of quasi-elastic neutron scattering measurements and molecular dynamics simulations. These two techniques were used to determine the self-diffusivities of H-2, and the corrected and transport diffusivities of CO2, as single components and binary mixture. H-2 was shown to be the faster of the two gases to diffuse through the narrow triangular channel of MIL-140A(Zr), its self-diffusivity value being 1 order of magnitude higher than that of CO2, at the same temperature. In this case, although no specific interaction sites are present, the CO2 interacts more strongly with the pore wall than H-2, partly a consequence of its greater kinetic radius, which renders it slower than H-2. In the context of a binary mixture, H-2 still diffuses faster between the two, although with a slightly lower self-diffusivity, while that of CO2 increases slightly. However, the difference in terms of order of magnitude is not altered and makes MIL-140A(Zr) a potential candidate for H-2/CO2 separation based on kinetics

Diffusion of Light Hydrocarbons in the Flexible MIL-53(Cr) Metal-Organic Framework: A Combination of Quasi-Elastic Neutron Scattering Experiments and Molecular Dynamics Simulations

International audienceThe dynamics of light hydrocarbons, including ethane, propane, and n-butane, is explored in the highly flexible metal-organic framework MIL-53(Cr) by combining quasi-elastic neutron scattering measurements and molecular dynamics simulations. The loading dependence of the self-diffusivity shows peculiarities, including (i) a relatively rapid decrease of D-s at low loading for ethane and propane and (ii) an unusual increase of D-s for n-butane at high loading, following a decreasing profile up to intermediate loading. These diffusion behaviors are analyzed in light of the structural flexibility of the solids upon alkane adsorption characterized by the neutron measurements. A 1D-type diffusion is evidenced for all alkanes with a jump sequence mainly ruled by the hydroxyl groups present at the surface of the MOF pore wall. This global translational motion is associated with a rotational dynamics that differs according to the nature of the alkane: whereas n-butane follows uniaxial displacements, ethane shows random rotational reorientation