In situ surface coverage analysis of RuO₂-catalysed HCl oxidation reveals the entropic origin of compensation in heterogeneous catalysis

In heterogeneous catalysis, rates with Arrhenius-like temperature dependence are ubiquitous. Compensation phenomena, which arise from the linear correlation between the apparent activation energy and the logarithm of the apparent pre-exponential factor, are also common. Here, we study the origin of compensation and find a similar dependence on the rate-limiting surface coverage term for each Arrhenius parameter. This result is derived from an experimental determination of the surface coverage of oxygen and chlorine species using temporal analysis of products and prompt gamma activation analysis during HCl oxidation to Cl2 on a RuO2 catalyst. It is also substantiated by theory. We find that compensation phenomena appear when the effect on the apparent activation energy caused by changes in surface coverage is balanced out by the entropic configuration contributions of the surface. This result sets a new paradigm in understanding the interplay of compensation effects with the kinetics of heterogeneously catalysed processes

First-principles calculations on the adsorption behavior of amino acids on a titanium carbide MXene

Due to their vast range of promising biomedical and electronic applications, there is a growing interest in bioinorganic lamellar nanomaterials. MXenes are one such class of materials, which stand out by virtue of their demonstrated biocompatibility, pharmacological applicability, energy storage performance, and feasibility as single-molecule sensors. Here, we report on first-principles predictions, based on density functional theory, of the binding energies and ground-state configurations of six selected amino acids (AAs) adsorbed on O-terminated two-dimensional titanium carbide, Ti2CO2. We find that most AAs (aspartic acid, cysteine, glycine, and phenylalanine) prefer to adsorb via their nitrogen atom, which forms a weak bond with a surface Ti atom, with bond lengths of around 2.35 Å. In contrast, histidine and serine tend to adsorb parallel to the MXene surface, with their α carbon about 3 Å away from it. In both adsorption configurations, the adsorption energies are on the order of the tenths of an electronvolt. In addition, we find a positive, nearly linear correlation between the binding energy of each studied AA and its van der Waals volume, which suggests an adsorption dominated by van der Waals forces. This relationship allowed us to predict the adsorption energies for all of the proteinogenic AAs on the same Ti2CO2 MXene. Our analysis additionally shows that in the parallel adsorption mode there is a negligible transfer of charge density from the AA to the surface but noticeable in the N-bonded adsorption mode. In the latter, the isosurfaces of charge density differences show accumulation of shared electrons in the region between N and Ti, confirming the predicted N–Ti bond. The moderate adsorption energy values calculated, as well as the preservation of the integrity of both the AAs and the surface upon adsorption, reinforce the capability of Ti2CO2 as a promising reusable biosensor for amino acids.publishe

Performance, structure, and mechanism of CeO₂ in HCl oxidation to Cl₂

Experimental and theoretical studies reveal performance descriptors and provide molecular-level understanding of HCl oxidation over CeO2. Steady-state kinetics and characterization indicate that CeO2 attains a significant activity level, which is associated with the presence of oxygen vacancies. Calcination of CeO2 at 1173 K prior to reaction maximizes both the number of vacancies and the structural stability of the catalyst. X-ray diffraction and electron microscopy of samples exposed to reaction feeds with different O2/HCl ratios provide evidence that CeO2 does not suffer from bulk chlorination in O2-rich feeds (O2/HCl ≥ 0.75), while it does form chlorinated phases in stoichiometric or sub-stoichiometric feeds (O2/HCl ≤ 0.25). Quantitative analysis of the chlorine uptake by thermogravimetry and X-ray photoelectron spectroscopy indicates that chlorination under O2-rich conditions is limited to few surface and sub-surface layers of CeO2 particles, in line with the high energy computed for the transfer of Cl from surface to sub-surface positions. Exposure of chlorinated samples to a Deacon mixture with excess oxygen rapidly restores the original activity levels, highlighting the dynamic response of CeO2 outermost layers to feeds of different composition. Density functional theory simulations reveal that Cl activation from vacancy positions to surface Ce atoms is the most energy-demanding step, although chorine-oxygen competition for the available active sites may render re-oxidation as the rate-determining step. The substantial and remarkably stable Cl2 production and the lower of CeO2 make it an attractive alternative to RuO2 for catalytic chlorine recycling in industry

Collective Impact Partnership and Backbone Organizations as Enablers of Children’s Well-Being

In this article, the question of partnership is approached from a perspective centred around the creation of a common agenda based on trust and from the children´s point of view. Partnership and collaboration have traditionally been viewed as mechanisms to create bridges between organisations and institutions from the private, public and non-governmental sectors in order to enhance funder collaboratives, public-private partnerships, multi-stakeholder initiatives, social sector networks and collective impact initiatives. It was not however until Kania and Kramer´s (2011) seminal work on collective impact when this subject came to be viewed as a developmental process aiming at the creation of a common agenda and mutually agreed activities and consisting of five integral parts: a common agenda, shared measurement systems, mutually reinforcing activities, continuous communication and backbone support organisations. This article, based on a systematic review of the topic, maintains that partnership – approached from the point of view of children and through the lens of collective impact – constitutes a crucial mechanism in the creation of safe and comprehensive wellbeing for children. Thus, this article – using Kania and Kramer´s (2011) definition of collective impact and focusing on the structure of partnerships and the nature of trust in organisations as the prerequisite for partnership – advocates the importance of the UN SDG17 principle as the bringer of inclusive society built upon principles and values, a shared vision, and shared goals that place people at the centre of human endeavour.© Springer Nature Switzerland AG 2020. This is a post-peer-review, pre-copyedit version of an article published in Partnerships for the Goals. Encyclopedia of the UN Sustainable Development Goals. The final authenticated version is available online at: http://dx.doi.org/10.1007/978-3-319-71067-9_111-1.fi=vertaisarvioitu|en=peerReviewed

Mass development of marine benthic Sarcinochrysidales (Chrysophyceae <i>s.l.</i>) in Corsica

A mass development of benthic Sarcinochrysidales (Chrysophyceae s.l.), especially of Chvysoreinhardia giraudii comb, nov. (basionym: Tetraspora giraudii) and Nematochrysopsis marina comb. nov. (basionym: Tribonema marinum), is reported from the Corsican coast. Morphology, habitat and seasonal development of these taxa as well as of the less regularly observed Chrysonephos lewisii and of some Chrysophyceae s.l. associated with Chrysoveinhardia giraudii sheaths are presented

Offices in Europe Towards a Principal-Agent Based Typology of Risks in Public-Private Partnerships

This Working Paper should not be reported as representing the views of the IMF. The views expressed in this Working Paper are those of the authors and do not necessarily represent those of the IMF or IMF policy. Working Papers describe research in progress by the authors and are published to elicit comments and to further debate. There is a strong economic rationale for close cooperation between the public and private sectors. This has resulted in a significant increase in the demand for the provision of public services through instruments combining public and private money such as public-private partnerships (PPPs or P3s). We describe these arrangements and explore how they can be analyzed using standard tools in economics (incentives and principal-agent theory). We discuss the implications of our approach in terms of identifying risks that are often overlooked before turining to the optimal risk-sharing between the public and private partners, in particular with respect to information asymmetries in risk perceptions. This allows us to propose a typology of the risks associated with PPPs, where both internal risks (the risks associated with the contract) and external risks (those associated with the project) are considered

Furin and proprotein convertase 7 (PC7)/lymphoma PC endogenously expressed in rat liver can be resolved into distinct post-Golgi compartments.

The intracellular compartmentalization in rat liver of the membrane-associated convertases furin and proprotein convertase 7 (PC7)/lymphoma PC (LPC) was investigated by analytical subcellular fractionation. In control animals, both enzymes were found to localize in fractions depleted of endoplasmic reticulum, cis-Golgi and lysosomal markers, but to co-distribute with the Golgi marker galactosyltransferase and the trans-Golgi network (TGN) marker TGN38. After overloading Golgi-derived vesicles with very-low-density lipoproteins (VLDL) by feeding rats with ethanol, the distribution of PC7/LPC was shifted markedly towards lower densities, in contrast with those of furin and the TGN marker. This provides support for the TGN localization of endogenously expressed furin and indicates that, at steady state, a considerable proportion of PC7/LPC may be associated with vesicles derived from the TGN