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

Elucidating structure–property relationships in aluminum alloy corrosion inhibitors by machine learning

Organic corrosion inhibitors are playing a crucial role to substitute traditional protective technologies, which have acute toxicity problems associated. However, why some organic compounds inhibit corrosion and others do not, is still not well understood. Therefore, we tested different machine learning (ML) methods to distinguish efficient corrosion inhibitors for aluminum alloys commonly used in aeronautical applications. In this work, we have obtained information that can greatly contribute to automate the search for new and more efficient protective solutions in the future: i) a ML algorithm was selected that is able to classify correctly efficient inhibitors (i.e., with more than 50 % efficiency) and non-inhibitors (i.e. with lower-equal than 50 % efficiency), even when information about different alloys at different pHs is included in the same dataset, which can significantly increase the information available to train the model; ii) new descriptors related to the self-association of the molecules were evaluated, but improvements to the predictive power of the models are limited; iii) average differences concerning the descriptors in this work were identified for inhibitors and non-inhibitors, having the potential to serve as guidelines to select potentially inhibitive molecular systems. This work demonstrates that ML can significantly accelerate research in the field by serving as a tool to perform an initial virtual screen of the molecules.publishe

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

Unveiling the local structure of 2-mercaptobenzothiazole intercalated in (Zn2Al) layered double hydroxides

The structure and composition of a zinc-aluminum layered double hydroxide (Zn2Al LDH) with the intercalated 2-mercaptobenzothiazole corrosion inhibitor (a.k.a. benzo[d]thiazole-2-thiol) are interpreted by means of atomistic molecular dynamics (MD) simulations. The results concerning the proportion of intercalated 2-mercaptobenzothiazole and water species in the Zn2Al LDH interlayer were correlated with experimental X-ray diffraction (XRD) and thermogravimetric analysis (TGA) data of samples obtained at pH 8.5, 10 and 11.5. While the sample synthesized at the lowest pH is almost free of contaminants, the sample obtained at the highest pH is contaminated by a small fraction of a material with intercalated OH-. The comparison of the calculated and XRD interlayer distances suggests that the most stable structure has a ratio of ~4.5 water molecules per intercalated organic species, which is higher than the ratio of ~2 typically reported in the literature. The distribution of molecules in the LDH interlayer consists of a layer of water near the hydroxides, a second layer grown over the first layer, with the 2-mercaptobenzothiazole species adopting conformations with the sulfur of the thioamide group facing the hydroxide/water layers and the 6-member ring oriented towards the middle of the interlayer. Different structural analyses were done to explain the equilibria between the different species in the interlayer space, and their molecular interactions with the LDH metal hydroxide layers.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

CORDATA: an open data management web application to select corrosion inhibitors

The large amount of corrosion inhibition efficiencies in literature, calls for a more efficient way to organize, access and compare this information. The CORDATA open data management application (https://datacor.shinyapps.io/cordata/) can help select appropriate corrosion inhibitors for application specific challenges.publishe

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

The compiler pays principle: The limits of fiscal approaches toward sustainable forest management

This paper examines the role and impact of taxation on sustainable forest management. It is shown that fiscal instruments neither reinforce nor substitute for traditional regulatory approaches and can actually undermine sustainability. The paper uses the reasoning at the root of the Faustmann solution to draw conclusions on the incentives for sustainable tropical forest exploitation. It proposes a bond mechanism as an alternative market-based instrument to encourage sustainable forest logging while reducing monitoring costs

The Complier Pays Principle

This paper examines the role and impact of taxation on sustainable forest management. It is shown that fiscal instruments neither reinforce nor substitute for traditional regulatory approaches. Far from encouraging more sustainable forest management, fiscal instruments such as an inappropriate tax policy can actually undermine it. The paper uses the arguments at the root of the Faustmann solution to draw conclusions on the incentives for sustainable tropical forest exploitation. The paper also proposes a bond mechanism as an alternative market-based instrument to encourage sustainable forest logging while reducing monitoring costs.Environment;forest, forest management, environmental damage, forests, sustainable forest management, natural forests, timber prices, soil erosion, forest degradation, environmental cost, forest health, forest leases, forest depletion, forest resources, industrial pollution, forest productivity, forest logging, environmental intelligence, forest policy, environmental benefits, sustainable forestry, forest land, natural resource management, timber taxation, forestry management, natural resources, forest concession, environmental taxes, forest conservation, marginal environmental cost, environmental degradation, concession management, environmental management, tropical forestry, land improvement, areas of forest, forest concessions, timber production, environmental services, timber sales, environmental economics, forestry sector, forest exploitation, forest operations, environmental policy, environmental incentive, forest harvesting, state forestry, area of forest, forest taxation, degraded forests, tropical forests, commercial timber exploitation, concession policies, forest managers, forest regulation, forest environments, environmental consequences, environmental impacts, environmental taxation, forest biodiversity, forest manager, environmentally sensitive areas, biodiversity conservation, environmentally sensitive, timber species, forest stock, forest administration, environmental economists, environmentally harmful ? technology, forest authorities, forest destruction, timber industry, environmental side effects