Insight into the reversible structural crystalline-state transformation from MIL-53(Al) to MIL-68(Al)

The reversible crystalline transformation between MIL-53(Al) and MIL-68(Al) is described. This followed a uniform conversion model with cleavage and formation of metal-ligand bonds after exchange or removal of guest molecules. MIL-68(Al) materials produced during the transformations had higher thermal stability and crystallinity than the as-synthesized MIL-68(Al)

Enhancement of growth of MOF MIL-68(Al) thin films on porous alumina tubes using different linking agents

The preparation of MIL-68(Al) films on the inner surface of alumina tubes is reported. As the direct deposition of the MOF on bare alumina gives poor adhesion results, three different linking agents are employed to achieve a good MOF–support interaction. Colloidal silica LUDOX®, zeolite silicalite-1, and natural polysaccharide chitosan are chosen as binders, because they contain potential functional groups (hydroxy, amino, ether), which can establish hydrogen bonds. While colloidal silica leads to noncontinuous MOF layers, silicalite-1 and chitosan give rise to uniform and well-anchored films, as confirmed by the different characterization techniques used to study the MOF layer. Single-gas permeation experiments are carried out to determine the quality and ideal efficiency of the membranes prepared with silicalite-1 and chitosan. The results for the MIL-68(Al)/silicalite-1 membranes evidence the existence of macrodefects. However, no cracks are found when chitosan is used as a linking agent, and the gas flow through the MIL-68(Al)/chitosan membranes clearly follows Knudsen diffusion

A comparative study between single gas and mixed gas permeation of polyether-block-amide type copolymer membranes

We analyze the gas separation performance of five polyether-block-amide type copolymers (Pebax® 1657, Renew®, 2533, 3533 and 4533). These codes are composed of different hard and rubbery segments with different proportions. Dense membranes were prepared by the casting-solution method and studied by elemental, thermogravimetric and X-ray diffraction analyses, FTIR-ATR spectroscopy and single and mixed gas permeation. Codes with the best separation performance are those of polyethylene oxide as the soft phase (Pebax® 1657 and Renew®) due to the more intense interactions of this segment with CO2, which increases the CO2/N2 solubility selectivity (17.5 and 30.5 for Pebax® 1657 and Renew®, respectively) and hence the CO2/N2 separation selectivity of the membrane (36 and 37 for Pebax® 1657 and Renew®, respectively, obtained from mixed gas permeation). It is also noticeable that the proportion of the soft phase in the copolymer determines the permeability of CO2. It was found that the codes with a greater soft/hard segment ratio (Pebax® 2533 and 3533) have also a greater permeability value (239 and 220 Barrer for Pebax® 2533 and 3533, respectively, measured by mixed gas permeation). Pebax® Renew® was the polymer with the best separation performance with CO2 permeabilities of 167 and 164 Barrer and CO2/N2 selectivities of 41 and 37, measured by single and mixed gas permeation, respectively. The comparison between the single and mixture gas permeation results revealed a relatively good correspondence between both for most of the Pebax® codes tuned by the solubility and diffusion properties of the polymers. © 2022 The Authors

Nanosheets of MIL-53(Al) applied in membranes with improved CO 2 /N 2 and CO 2 /CH 4 selectivities

MIL-68(Al) and MIL-53(Al) are carboxylate-based metal-organic frameworks (MOFs) with the same chemical composition but different structures (polymorphs). In this study, MIL-53(Al) nanosheets of ca. 150 nm in size with an average thickness of 3.5 ± 0.9 nm were obtained after immersion of a sample composed of MIL-68(Al) and MIL-53(Al) in water under different conditions (ultrasound, stirring, reflux, 60 °C and room temperature). The disaggregated MIL-53(Al) nanosheets produced under more severe conditions were suspended in a PDMS solution and then deposited on asymmetric polyimide P84® supports under vacuum filtration to form supported mixed matrix membranes (MMMs). When applied to the separation of CO 2 /CH 4 and CO 2 /N 2 mixtures, the MMM with MIL-53(Al) nanosheets improved the CO 2 /CH 4 (28.4-28.7 vs. 22.4) and CO 2 /N 2 (19.9-23.2 vs. 17.5) selectivities of the conventional MIL-53(Al) MMM with higher CO 2 permeances (20.8-29.6 GPU vs. 9.5 GPU for CO 2 /CH 4 and 17.7-26.8 GPU vs. 11.2 GPU for CO 2 /N 2 )

Second-Generation Drosophila Chemical Tags: Sensitivity, Versatility, and Speed

Labeling and visualizing cells and subcellular structures within thick tissues, whole organs and even intact animals is key to studying biological processes. This is particularly true for studies of neural circuits where neurons form submicron synapses but have arbors that may span millimeters in length. Traditionally, labeling is achieved by immunofluorescence; however diffusion of antibody molecules (>100 kDa) is slow and often results in uneven labeling with very poor penetration into the centre of thick specimens; these limitations can be partially addressed by extending staining protocols to over a week (Drosophila brain) and months (mice). Recently we developed an alternative approach using genetically encoded chemical tags CLIP, SNAP, Halo and TMP for tissue labeling; this resulted in >100 fold increase in labeling speed in both mice and Drosophila, at the expense of a considerable drop in absolute sensitivity when compared to optimized immunofluorescence staining. We now present a second generation of UAS and LexA responsive CLIPf, SNAPf and Halo chemical labeling reagents for flies. These multimerized tags, with translational enhancers, display up to 64 fold increase in sensitivity over first generation reagents. In addition we developed a suite of conditional reporters (4xSNAPf tag and CLIPf-SNAPf-Halo2) that are activated by the DNA recombinase Bxb1. Our new reporters can be used with weak and strong GAL4 and LexA drivers and enable stochastic, intersectional and multicolor Brainbow labeling. These improvements in sensitivity and experimental versatility, while still retaining the substantial speed advantage that is a signature of chemical labeling, should significantly increase the scope of this technology.This work was supported by the Medical Research Council (MRC file reference U105188491 and U105178788), European Research Council Starting Investigator (211089) and Consolidator grants (649111) to G.S.X.E.J., and a Royal Society Dorothy Hodgkin Fellowship to S.C. T.O.A. is supported by a Human Frontier Science Program Long Term Fellowship. Research in R.B.’s laboratory is supported by the University of Lausanne and an ERC Consolidator grant (615094). Stocks obtained from the Bloomington Drosophila Stock Center (NIH P40OD018537) were used in this study

Radiation tests on commercial instrumentation amplifiers, analog switches & DAC's

A study of several commercial instrumentation amplifiers (INA110, INA111, INA114, INA116, INA118 & INA121) under neutron and vestigial gamma radiation was done. Some parameters (Gain, input offset voltage, input bias currents) were measured on-line and bandwidth, and slew rate were determined before and after radiation. The results of the testing of some voltage references REF102 and ADR290GR and the DG412 analog switch are shown. Finally, different digital-to-analog converters were tested under radiation. (6 refs)

Radiation tests on commercial instrumentation amplifiers, analog switches & DAC's

A study of several commercial instrumentation amplifiers (INA110, INA111, INA114, INA116, INA118 & INA121) under neutron and vestigial gamma radiation was done. Some parameters (Gain, input offset voltage, input bias currents) were measured on-line and bandwidth, and slew rate were determined before and after radiation. The results of the testing of some voltage references REF102 and ADR290GR and the DG412 analog switch are shown. Finally, different digital-to-analog converters were tested under radiation

Updated Iberian archeomagnetic catalogue: new full vector paleosecular variation curve for the last three millennia

In this work, we present 16 directional and 27 intensity high‐quality values from Iberia. Moreover, we have updated the Iberian archeomagnetic catalogue published more than 10 years ago with a considerable increase in the database. This has led to a notable improvement of both temporal and spatial data distribution. A full vector paleosecular variation curve from 1000 BC to 1900 AD has been developed using high‐quality data within a radius of 900 km from Madrid. A hierarchical bootstrap method has been followed for the computation of the curves. The most remarkable feature of the new curves is a notable intensity maximum of about 80 μT around 600 BC, which has not been previously reported for the Iberian Peninsula. We have also analyzed the evolution of the paleofield in Europe for the last three thousand years and conclude that the high maximum intensity values observed around 600 BC in the Iberian Peninsula could respond to the same feature as the Levantine Iron Age Anomaly, after travelling westward through Europe