Harvesting vibrational energy with liquid-bridged electrodes: thermodynamics in mechanically and electrically driven RC-circuits

We theoretically study a vibrating pair of parallel electrodes bridged by a (deformed) liquid droplet, which is a recently developed microfluidic device to harvest vibrational energy. The device can operate with various liquids, including liquid metals, electrolytes, as well as ionic liquids. We numerically solve the Young-Laplace equation for all droplet shapes during a vibration period, from which the time-dependent capacitance follows that serves as input for an equivalent circuit model. We first investigate two existing energy harvesters (with a constant and a vanishing bias potential), for which we explain an open issue related to their optimal electrode separations, which is as small as possible or as large as possible in the two cases, respectively. Then we propose a new engine with a time-dependent bias voltage, with which the harvested work and the power can be increased by orders of magnitude at low vibration frequencies and by factors 2-5 at high frequencies, where frequencies are to be compared to the inverse RC-time of the circuit.Comment: 9 pages, 6 figure

Coulometry and Calorimetry of Electric Double Layer Formation in Porous Electrodes

Coulometric measurements on salt-water-immersed nanoporous carbon electrodes reveal, at a fixed voltage, a charge decrease with increasing temperature. During far-out-of-equilibrium charging of these electrodes, calorimetry indicates the production of both irreversible Joule heat and reversible heat, the latter being associated with entropy changes during electric double layer (EDL) formation in the nanopores. These measurements grant experimental access --for the first time-- to the entropic contribution of the grand potential; for our electrodes, this amounts to roughly 25% of the total grand potential energy cost of EDL formation at large applied potentials, in contrast with point-charge model calculations that predict 100%. The coulometric and calorimetric experiments show a consistent picture of the role of heat and temperature in EDL formation and provide hitherto unused information to test against EDL models.Comment: 11 pages, 10 figure

A systematic review of ethical challenges and opportunities of addressing domestic violence with AI-technologies and online tools

Domestic violence remains a pressing complex social problem of people of any gender, age, socio-economic status, and ethno-cultural background, an issue that worsened worldwide during the COVID-19 pandemic. Digital, online, or artificial intelligence-based smart technological services, applications, and tools provide novel approaches in addressing domestic violence, including intimate partner violence. This systematic literature review analyses the ethical challenges and opportunities these (protective) digital and smart technologies provide to the stakeholders involved. Our results highlight that the public health and societal issue are the leading narratives of domestic violence, which is predominantly interpreted as gender-based violence. The review highlights an emerging trend of the role of machine learning- and artificial intelligence-based approaches in identifying and preventing domestic violence. However, we argue that little recommendation is available to professionals about how to use these approaches in a responsible way, and that the smartness of high-tech technologies is often challenged by basic-level technologies from perpetrators, creating an imbalance that also limits an impactful development of a comprehensive socio-technical regime that serves the safety and resilience of families in their communal setting

Publiek – private samenwerking bij combinatie projecten

Publiek-private samenwerking (PPS) krijgt veel aandacht als wijze van uitvoering van projecten waarin investeringen in infrastructuur (bijvoorbeeld in een station voor de hogesnelheidslijn) gecombineerd worden met stedelijke vernieuwing en investeringen in vastgoed. Het gaat om zogenaamde Combinatieprojecten. Doel van dit onderzoek is bij te dragen aan inzicht in de voorwaarden waaronder de mogelijke voordelen van PPS bij Combinatieprojecten zijn te realiseren. De focus hierbij is hoe publieke belangen het best gerealiseerd kunnen worden. We richten ons daartoe op het Rijk en de gemeenten. Deze keuze impliceert geenszins dat de problematiek benaderd wordt vanuit het idee dat het de ´goedwillende overheid´ tegen de ´gehaaide private partijen´ is. De doelstelling van private partijen is in de regel overzichtelijk: het maximaliseren van winst. Daartegenover staat een complexe verzameling mogelijk tegengestelde publieke belangen. De vraag is hoe de kracht van private partijen benut kan worden om die complexe verzameling publieke doelen te realiseren. Daarbij liggen de kansen van PPS vooral in een hoger maatschappelijk rendement door uitruil van prestaties en een betere risicoverdeling tussen de partijen. De risico's van PPS zitten vooral in de afhankelijkheid van andere partijen. De twee vragen die in dit onderzoek centraal staan zijn: Welke afwegingen zijn voor het Rijk en de gemeenten van belang bij het kiezen voor PPS bij Combinatieprojecten? Gegeven een keuze voor PPS, welke factoren dragen bij tot coöperatief gedrag van alle betrokken partijen in de diverse fasen van een Combinatieproject

Enantiomerically pure β-phenylalanine analogues from α–β-phenylalanine mixtures in a single reactive extraction step

An efficient and selective method for the extraction of α-amino acids in preference over their β-isomers using PdCl2(PPh3)2 was discovered, which enables the separation of product mixtures obtained in the enantioselective enzymatic formation of β-amino acids.

One pot ‘click’ reactions: tandem enantioselective biocatalytic epoxide ring opening and [3+2] azide alkyne cycloaddition

Halohydrin dehalogenase (HheC) can perform enantioselective azidolysis of aromatic epoxides to 1,2-azido alcohols which are subsequently ligated to alkynes producing chiral hydroxy triazoles in a one-pot procedure with excellent enantiomeric excess.

Non-Markovian Persistence and Nonequilibrium Critical Dynamics

The persistence exponent \theta for the global order parameter, M(t), of a system quenched from the disordered phase to its critical point describes the probability, p(t) \sim t^{-\theta}, that M(t) does not change sign in the time interval t following the quench. We calculate \theta to O(\epsilon^2) for model A of critical dynamics (and to order \epsilon for model C) and show that at this order M(t) is a non-Markov process. Consequently, \theta is a new exponent. The calculation is performed by expanding around a Markov process, using a simplified version of the perturbation theory recently introduced by Majumdar and Sire [Phys. Rev. Lett. _77_, 1420 (1996); cond-mat/9604151].Comment: 4 pages, Revtex, no figures, requires multicol.st