On controlling the anodic electrochemical film deposition of HKUST-1 metal-organic frameworks

© 2016 Elsevier Inc. All rights reserved. Anodic electrochemical synthesis presents itself as a powerful and rapid method to produce porous metal-organic framework (MOF) powders and deposit MOF films onto metal surfaces. Such layers are of interest for adsorptive, catalytic or sensor applications. However, electrochemical MOF synthesis is still in a preliminary stage while a need to better control the process and understand the influences of the process parameters emerges. This work focuses on controlling the deposition of copper-1,3,5-benzenetricarboxylate (HKUST-1, Cu-BTC) MOF layers and targeting different crystal sizes. Moreover, it aims to shed some light on the mechanisms underlying these changes. A number of strategies can be adopted to control the process and adjust the obtained crystal size. By adjusting the synthesis time or water content, the average crystal size can be controlled up to ∼10 μm for ethanol-based synthesis mixtures. The potential also has a pronounced effect, yet a suitable operation window must first be determined to avoid incomplete film formation or excessive film detachment. Furthermore, the influence of the solvent composition on the deposited film morphologies was investigated for mixtures of water, methanol, ethanol, 2-propanol, acetonitrile, N,N-dimethylformamide and dimethylsulfoxide.status: publishe

Stepped water isotherm and breakthrough curves on aluminium fumarate metal–organic framework: experimental and modelling study

Adsorption of water vapour on the Al-fumarate metal–organic framework (MOF) was studied in static and dynamic conditions, by performing gravimetric and fixed bed experiments. A two-step, type IV water isotherm is obtained, which reveals the complexity and the duality of the hydrophilic/hydrophobic behaviour of this MOF. Breakthrough experiments with feed conditions corresponding to three different zones in the water adsorption isotherm were performed to study the effect of isotherm shape on the column dynamics. At low partial pressure of water in the feed, a single breakthrough step is observed while a stepped profile is observed at higher partial pressure of water. These breakthrough curves could be described qualitatively with a simple model accounting for the isotherm shape.status: publishe

Adsorption and separation of small hydrocarbons on the flexible, vanadium-containing MOF, COMOC-2

COMOC-2, a flexible vanadium-containing metal, organic framework, was investigated for its adsorption and separation properties of light hydrocarbons, COMOC-2 is an extended version of the MIL-47 framework with 4,4'-biphenyldicarboxylic acid linkers instead of tetephthalic acid. Adsorption isotherms of methane to propane, ethylene, and propylene were determined with a gravimetric uptake technique at temperatures between 281 and 303 K. A pronounced breathing effect was observed (in contrast to the more rigid MIL-47 framework) in which the adsorption capacity increases by more than a factor of 2 at a given breathing pressure. The breathing pressure decreases with increasing hydrocarbon molecular weight. The typical two-step isotherms are nearly identical for alkanes and alkenes, hi accordance with the nonpolar nature of the material. Binary isotherms of ethane and propane were also measured with the gravimetric uptake technique at different temperatures and total pressures. The mixture isotherms and breathing transition pressures were predicted by relying on the osmotic framework adsorbed solution theory (OFAST). Finally, the separation potential of COMOC-2 for ethane/propane mixtures was looked into using breakthrough experiments for different compositions and different pressures

On the electrochemical deposition of Metal-Organic Frameworks

The electrochemical deposition of Metal-Organic Frameworks (MOFs) is an interesting technique to synthesize adherent, microporous layers on top of metal substrates. However, up to now not much is known about this process, and in this paper a four phase mechanism is proposed to better understand it. The study focuses on how the nucleation of these compounds starts and proceeds, what the influence of the solvent is, the stresses in the growing layers, and the origin of defects like delamination and crystal detachment.status: publishe

On the electrochemical deposition of metal-organic frameworks

The electrochemical deposition of Metal–Organic Frameworks (MOFs) is an interesting technique to synthesise adherent, microporous layers on top of conductive substrates. The technique can be subdivided in two approaches: anodic and cathodic deposition. While the mechanism of the cathodic approach has already been well investigated, at least for MOF-5, up to now not much is known about the anodic approach. In this paper, a four-step mechanism is proposed to better understand the anodic deposition, and the same MOF used for the investigation, HKUST-1, is also deposited cathodically to compare the two approaches. This study focuses on how nucleation starts and proceeds, on the influence of the potential applied, the stresses in the growing layers, and the origin of defects like delamination and MOF detachment. The study is followed by critical considerations on the methods and on the technique, together with suggestions and guidelines to synthesise new MOF layers.status: publishe

Strong Upregulation of AIM2 and IFI16 Inflammasomes in the Mucosa of Patients with Active Inflammatory Bowel Disease

BACKGROUND: Inflammatory bowel disease (IBD) is characterized by a chronic inflammation of the gut, partly driven by defects in the innate immune system. Considering the central role of inflammasome signaling in innate immunity, we studied inflammasome components in IBD mucosa. METHODS: Expression of genes encoding inflammasome sensor subunits was investigated in colonic mucosal biopsies from 2 cohorts of patients with IBD and controls. RESULTS: A significant upregulation (>2-fold change in expression, false discovery rate <0.05) of the PYHIN inflammasomes AIM2 and IFI16 in active IBD versus controls was found. Also IFI16 was significantly increased in inactive IBD versus controls. Moreover, responders to anti-tumor necrosis factor therapy showed decreased expression of these inflammasomes although IFI16 remained significantly increased in responders showing endoscopic healing versus controls. AIM2 was mainly expressed in epithelial cells, whereas IFI16 was expressed in both lymphocytes and epithelial cells. Functional activation of predominant AIM2/IFI16-mediated inflammasomes in active IBD colon was shown by the presence of the downstream effectors CASP1 and HMGB-1 in inflamed mucosa. CONCLUSIONS: Our results highlight the importance of PYHIN inflammasome signaling in IBD and also link anti-tumor necrosis factor responsiveness to inflammasome signaling. Together, this points to the potential value of the inflammasome pathway as a new therapeutic target for IBD treatment.status: publishe

Consensus for managing acute severe ulcerative colitis in children: a systematic review and joint statement from ECCO, ESPGHAN, and the Porto IBD Working Group of ESPGHAN.

OBJECTIVES: Acute severe ulcerative colitis (ASC) is a potentially life-threatening disease. We aimed to formulate guidelines for managing ASC in children based on systematic review of the literature and robust consensus process. This manuscript is a product of a joint effort of the ECCO (European Crohn's and Colitis Organization), the Pediatric Porto Inflammatory Bowel Disease (IBD) Working group of ESPGHAN (European Society of Pediatric Gastroenterology, Hepatology, and Nutrition) and ESPGHAN. METHODS: A group of 19 experts in pediatric IBD participated in an iterative consensus process including two face-to-face meetings. A total of 17 predefined questions were addressed by working subgroups based on a systematic review of the literature. RESULTS: The recommendations and practice points were eventually endorsed with a consensus rate of at least 95% regarding: definitions, initial evaluation, standard therapy, timing of second-line therapy, the role of endoscopic evaluation and heparin prophylaxis, how to administer second-line medical therapy, how to assess response, surgical considerations, and discharge recommendations. A management flowchart is presented based on daily scoring of the Pediatric Ulcerative Colitis Activity Index (PUCAI), along with 28 formal recommendations and 34 practice points. CONCLUSIONS: These guidelines provide clinically useful points to guide the management of ASC in children. Taken together, the recommendations offer a standardized protocol that allows effective monitoring of disease progress and timely treatment escalation when needed