527 research outputs found

    Synthetic routes toward MOF nanomorphologies.

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    As metal–organic frameworks (MOFs) are coming of age, their structural diversity, exceptional porosity and inherent functionality need to be transferred into useful applications. Fashioning MOFs into various shapes and at the same time controlling their size constitute an essential step toward MOF-based devices. Moreover, downsizing MOFs to the nanoscale triggers a whole new set of properties distinguishing nanoMOFs from their bulk counterparts. Therefore, dimensionality-controlled miniaturization of MOFs enables the customised use of nanoMOFs for specific applications where suitable size and shape are key prerequisites. In this feature article we survey the burgeoning field of nanoscale MOF synthesis, ranging from classical protocols such as microemulsion synthesis all the way to microfluidic-based techniques and template-directed epitaxial growth schemes. Along these lines, we will fathom the feasibility of rationally designing specific MOF nanomorphologies—zero-, one- and two-dimensional nanostructures—and we will explore more complex “second-generation” nanostructures typically evolving from a high level of interfacial control. As a recurring theme, we will review recent advances made toward the understanding of nucleation and growth processes at the nanoscale, as such insights are expected to further push the borders of nanoMOF science

    Biosystem for the culture and electrical characterisation of epithelial cell tissues

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    The aim of this work was to develop a microchamber system for performing electrophysiological measurements on epithelial surface on culture membranes in the mm2 range. This miniaturised system permits the use of small quantities of epithelial cells, which in relatively short time grow into a tight layer that can be used in electrophysiological (ion transport) experiments. Availability of cells is an issue, for example when the cells originate from human biopsies or from (expensive!) transgenic mice. Apart from having reduced culture surfaces (for use with scarce biological tissues), there are tremendous advantages in having a cell culture mini-chamber. Our systems are with integrated electrical electrodes, micro-fluidic channels and feed-throughs, making them extremely compact and easy to use, thereby avoiding cell perturbation by manipulations. The structures facilitate control of the cell layer growth, the measurement of the cell layer resistance and the transport and diffusion of biological or pharmacological molecules through the cell layer. Moreover we have chosen cheap and easy-to-tool materials for the realisation of disposable devices. We have also fabricated modular devices, in which the cell culture membranes can be reversibly placed within or removed from the system, thereby offering flexibility and economic interest. These microsystems (for biological applications ("biosystems")) are realised using photolithography, various etching procedures (among which powder-blasting), thin film deposition, electrochemical deposition, polydimethylsiloxane (PDMS) moulding and gluing technologies. Both electrical and fluidic characterisation of the biosystems has been performed. Also, a specific study of microelectrode properties of different electrode materials, such as Pt, Ag and Ag/AgCl has been done using various electrochemical experiments and models. The devices are finally tested in real biological experiments. These experiments were carried on with the collaboration of three different biological academic work groups: the group of Prof. W. Hunziker from the Institute of Biochemistry at the University of Lausanne, the group of Prof. Van der Goot from the Department of Biochemistry at the University of Geneva and Prof. J.D. Horisberger from the Institute of Pharmacology and Toxicology at the University of Lausanne. The functionality of our devices has been tested and their potential for the study of transport and diffusion of biological or pharmacological molecules through the cell layer via accurate measurement of (bio-) chemically induced resistance variations, has been demonstrated

    Influence of Citrate and Phosphate on the Adsorption of Adenosine-5′-Monophosphate at the Hematite Water Interface

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    Nucleic acid derived organic phosphorus (Po) is an important source of plant available P when degraded to inorganic phosphate (P(V)i). It is known that when nucleic acids or components are adsorbed on mineral surfaces, the enzymatic degradation is hindered or delayed. Thus, understanding adsorption/desorption mechanisms of nucleic acids and their derivatives are key to assess the biogeochemical pathways of Po cycling. Here we report adsorption mechanisms of adenosine-5′-monophosphate (AMP) on hematite, a common iron oxide mineral, under various solution properties using macroscopic and in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic probes. The effects of citrate, mimicking organic acids from roots exudates, and the influence of P(V)i, representing inorganic fertilizer application, were also evaluated on the release of adsorbed AMP under various solution properties. The results suggested that AMP adsorbed with the hematite surface via the phosphate moiety, N7 atom and the π electron systems of the adenine moiety. The presence of citrate significantly decreased the AMP adsorption, which was also corroborated by the negative phosphate IR bands in the results of AMP and citrate competitive adsorption experiments monitored by in situ ATR-FTIR probe. Like citrate, P(V)i also reduced AMP adsorption on hematite. Our findings suggest a potential novel pathway of nucleic acid derived Po cycling in the soil environment

    Organic Aqua Regia: Discovery, Fundamentals, and Potential Applications

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    Magnetism, FeS colloids, and Origins of Life

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    A number of features of living systems: reversible interactions and weak bonds underlying motor-dynamics; gel-sol transitions; cellular connected fractal organization; asymmetry in interactions and organization; quantum coherent phenomena; to name some, can have a natural accounting via physicalphysical interactions, which we therefore seek to incorporate by expanding the horizons of `chemistry-only' approaches to the origins of life. It is suggested that the magnetic 'face' of the minerals from the inorganic world, recognized to have played a pivotal role in initiating Life, may throw light on some of these issues. A magnetic environment in the form of rocks in the Hadean Ocean could have enabled the accretion and therefore an ordered confinement of super-paramagnetic colloids within a structured phase. A moderate H-field can help magnetic nano-particles to not only overcome thermal fluctuations but also harness them. Such controlled dynamics brings in the possibility of accessing quantum effects, which together with frustrations in magnetic ordering and hysteresis (a natural mechanism for a primitive memory) could throw light on the birth of biological information which, as Abel argues, requires a combination of order and complexity. This scenario gains strength from observations of scale-free framboidal forms of the greigite mineral, with a magnetic basis of assembly. And greigite's metabolic potential plays a key role in the mound scenario of Russell and coworkers-an expansion of which is suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed Krishnaswami Alladi, Springer 201

    The 2021 flexible and printed electronics roadmap

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    This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies
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