Metal organic framework nanosheets in polymer composite materials for gas separation

[EN] Composites incorporating two-dimensional nanostructures within polymeric matrices have potential as functional components for several technologies, including gas separation. Prospectively, employing metal-organic frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of freestanding nanosheets has proved challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometre lateral dimensions and nanometre thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO2 separation performance from CO2/CH4 gas mixtures, together with an unusual and highly desired increase in the separation selectivity with pressure. As revealed by tomographic focused ion beam scanning electron microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared with isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF-polymer composites for various applications.The research leading to these results has received funding (J.G., B.S.) from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 335746, CrystEng-MOF-MMM. T.R. is grateful to TUDelft for funding. G.P. acknowledges the A. von Humboldt Foundation for a research grant. A.C., I.L. and F.X.L.i.X. thank Consolider-Ingenio 2010 (project MULTICAT) and the ‘Severo Ochoa’ programme for support. 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Quantification of thickness and wrinkling of exfoliated two-dimensional zeolite nanosheets

Some two-dimensional (2D) exfoliated zeolites are single- or near single-unit cell thick silicates that can function as molecular sieves. Although they have already found uses as catalysts, adsorbents and membranes precise determination of their thickness and wrinkling is critical as these properties influence their functionality. Here we demonstrate a method to accurately determine the thickness and wrinkles of a 2D zeolite nanosheet by comprehensive 3D mapping of its reciprocal lattice. Since the intensity modulation of a diffraction spot on tilting is a fingerprint of the thickness, and changes in the spot shape are a measure of wrinkling, this mapping is achieved using a large-angle tilt-series of electron diffraction patterns. Application of the method to a 2D zeolite with MFI structure reveals that the exfoliated MFI nanosheet is 1.5 unit cells (3.0 nm) thick and wrinkled anisotropically with up to 0.8 nm average surface roughness. © 2015 Macmillan Publishers Limited

Systolic blood pressure measurements are unreliable for the management of acute spontaneous intracerebral hemorrhage

Purpose: Whether systolic blood pressure (SBP) is reliable in acute spontaneous intracerebral (sICH) by assessing agreement between simultaneous BP measurements obtained from cuff non-invasive blood pressure (NIBP) and radial arterial invasive blood pressure (AIBP) devices. Material and methods: Among 766 prospectively screened sICH subjects, 303 (39.5%) had NIBP and AIBP measurements. During the first 24 h, 2157 simultaneous paired measurement readings were abstracted. Paired NIBP/AIBP measurements were included in a Bland-Altman technique with 95% agreement limits and coefficients from regression analysis derived from a bootstrap procedure. Results: Variance for SBP was 66.1 mmHg, which was larger than the 44.3 mg Hg for diastolic blood pressure (DBP) or the 46.1 mmHg for mean arterial pressure (MAP). Pairwise comparison of mean biases showed a significant difference between SBP when compared to DBP (p \u3c 0.0001) or MAP (p \u3c 0.0001). The mean bias between DBP and MAP was not different (p = 0.68). Regression-based Bland Altman analysis found significant bias (slope -0.16, 95% CI -0.23, -0.09, p \u3c 0.05) over the range of mean SBP. Bias over the range of mean DBP or MAP was not significant. Conclusions: We concluded that SBP is an unreliable blood pressure measurement in patients with sICH

Systolic blood pressure measurements are unreliable for the management of acute spontaneous intracerebral hemorrhage.

PURPOSE: Whether systolic blood pressure (SBP) is reliable in acute spontaneous intracerebral (sICH) by assessing agreement between simultaneous BP measurements obtained from cuff non-invasive blood pressure (NIBP) and radial arterial invasive blood pressure (AIBP) devices. MATERIAL AND METHODS: Among 766 prospectively screened sICH subjects, 303 (39.5%) had NIBP and AIBP measurements. During the first 24 h, 2157 simultaneous paired measurement readings were abstracted. Paired NIBP/AIBP measurements were included in a Bland-Altman technique with 95% agreement limits and coefficients from regression analysis derived from a bootstrap procedure. RESULTS: Variance for SBP was 66.1 mmHg, which was larger than the 44.3 mg Hg for diastolic blood pressure (DBP) or the 46.1 mmHg for mean arterial pressure (MAP). Pairwise comparison of mean biases showed a significant difference between SBP when compared to DBP (p \u3c 0.0001) or MAP (p \u3c 0.0001). The mean bias between DBP and MAP was not different (p = 0.68). Regression-based Bland Altman analysis found significant bias (slope -0.16, 95% CI -0.23, -0.09, p \u3c 0.05) over the range of mean SBP. Bias over the range of mean DBP or MAP was not significant. CONCLUSIONS: We concluded that SBP is an unreliable blood pressure measurement in patients with sICH

Zeolite nanosystems: Imagination has no limits

ISSN:1755-4349ISSN:1755-433

Dispersible exfoliated zeolite nanosheets and their application as a selective membrane

Thin zeolite films are attractive for a wide range of applications, including molecular sieve membranes, catalytic membrane reactors, permeation barriers, and low-dielectric-constant materials. Synthesis of thin zeolite films using high-aspect-ratio zeolite nanosheets is desirable because of the packing and processing advantages of the nanosheets over isotropic zeolite nanoparticles. Attempts to obtain a dispersed suspension of zeolite nanosheets via exfoliation of their lamellar precursors have been hampered because of their structure deterioration and morphological damage (fragmentation, curling, and aggregation). We demonstrated the synthesis and structure determination of highly crystalline nanosheets of zeolite frameworks MWW and MFI. The purity and morphological integrity of these nanosheets allow them to pack well on porous supports, facilitating the fabrication of molecular sieve membranes