Shear wave sensors for viscoelastic properties

AbstractElectromechanical resonators are sensitive to the properties of the surrounding medium due to interaction forces onto the surface caused by motions in the medium. In the present contribution, fully metallic Lorentz force resonators exhibiting in-plane oscillation are used to excite shear waves to measure the linear viscoelastic storage and loss-moduli at specific frequencies in the kHz range of complex fluids (e.g. aqueous polymeric solutions). Reflected shear waves in a well defined gap are employed to extend the measurement range as well as the capability to measure at multiple frequencies. Numerical methods and reduced order models are employed to solve for the velocity field and interaction forces to determine the required quantities from the measured frequency response

Chlorination of a Zeolitic-Imidazolate Framework Tunes Packing and van der Waals Interaction of Carbon Dioxide for Optimized Adsorptive Separation

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.0c08942.L.H.W. acknowledges the Fonds Wetenschappelijk Onderzoek (FWO) - Vlaanderen for a senior postdoctoral research fellowship and International Mobility fellowship under contract numbers of 12M1418N and V402319N, respectively. S.V.D.B., S.M.J.R., and J.W. acknowledge Fonds Wetenschappelijk Onderzoek (FWO) - Vlaanderen for Grants 11U1914N, 12T3519N, and 1103618N as well as the Research Board of Ghent University (BOF). J.A.R.N. acknowledges generous funding from the Spanish Ministry of Economy (CTQ2014- 53486-R) and FEDER from the European Union. Funding was also received from the European Union’s Horizon 2020 Research and Innovation Programme [ERC Consolidator Grant Agreement 647755 - DYNPOR (2015−2020)]. J.A.M. and C.E.A.K. gratefully acknowledge financial support from the Flemish Government (Long-term structural funding Methusalem and FWO support). Collaboration among universities was supported by the Belgian Government (IAP-PAI network).Molecular separation of carbon dioxide (CO2) and methane (CH4) is of growing interest for biogas upgrading, carbon capture and utilization, methane synthesis and for purification of natural gas. Here, we report a new zeolitic-imidazolate framework (ZIF), coined COK-17, with exceptionally high affinity for the adsorption of CO2 by London dispersion forces, mediated by chlorine substituents of the imidazolate linkers. COK-17 is a new type of flexible zeolitic-imidazolate framework Zn(4,5-dichloroimidazolate)(2) with the SOD framework topology. Below 200 K it displays a metastable closed-pore phase next to its stable open-pore phase. At temperatures above 200 K, COK-17 always adopts its open-pore structure, providing unique adsorption sites for selective CO2 adsorption and packing through van der Waals interactions with the chlorine groups, lining the walls of the micropores. Localization of the adsorbed CO2 molecules by Rietveld refinement of X-ray diffraction data and periodic density functional theory calculations revealed the presence and nature of different adsorption sites. In agreement with experimental data, grand canonical Monte Carlo simulations of adsorption isotherms of CO2 and CH4 in COK-17 confirmed the role of the chlorine functions of the linkers and demonstrated the superiority of COK-17 compared to other adsorbents such as ZIF-8 and ZIF-71.FWO 12M1418N V402319N 11U1914N 12T3519N 1103618NSpanish Ministry of Economy CTQ201453486-RFEDER from the European UnionEuropean Union's Horizon 2020 Research and Innovation Programme [ERC] 647755 - DYNPORFlemish Government (Long-term structural funding Methusalem)FWOBelgian Government (IAP-PAI network

Viscoelasticity Sensor with Resonance Tuning and Low-Cost Interface

AbstractElectromechanical resonators are sensitive to the material parameters of a surrounding medium and therefore can be used as sensors for viscoelastic properties and density. In our recent work, we presented a metallic plate resonator excited by Lorentz forces in a permanent magnetic field. We improved the interface circuitry by using signal transformers, so that it is now possible to make accurate measurements using a commonly available low-cost audio- interface. Beside that, the necessary sample volume is reduced to a maximum of 50μl, so that a drop of liquid covers the sensitive area. Using a reflector parallel to the oscillation plane, standing waves in the gap could be generated. A desirable feature of resonator sensors is tunability over a significant frequency range. We investigated mechanisms to change the resonance frequency, e.g. an electric current that induces thermal stress. These advancements pave the way for a versatile low-cost, easy-to-use solution to measure viscoelastic properties in numerous applications

Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminum Content and Topology of Crystallizing Zeolites

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Formation mechanisms for new zeolite materials from a molecular modeling perspective

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