69 research outputs found
Successful endonasal dacryocystorhinostomy in a patient with Wegener’s granulomatosis
Wegener’s granulomatosis (WG) is one form of idiopathic autoimmune vasculitis. The disease has a predilection for the upper and lower respiratory tracts (lungs, nose, sinus), and kidneys. WG may be systemic, severe, and potentially lethal, but it may also be limited to the otolaryngological area or to the eyes and the orbits. Obstruction of the lacrimal pathway is a possible complication of the disease that affects approximately 7% of patients with WG. It usually occurs as a direct extension of sinonasal disease and typically is a late manifestation. Management of such a condition is generally viewed as difficult. We report the case of a patient with a quiescent WG limited to the otolaryngological area. This patient presented a bilateral obstruction of the nasolacrimal ducts caused by bilateral extensive adhesions in the nasal cavity. Because she had several episodes of left-side acute dacryocystitis which necessitated several courses of broad-spectrum antibiotics, she successfully underwent an endonasal endoscopic dacryocystorhinostomy using a diode laser and powered instrumentation. The authors describe the clinical case, the surgical technique, and review the literature
Putting Brexit into perspective: the effect of the Eurozone and migration crises and Brexit on Euroscepticism in European states
This paper examines the link between recent EU crises and the development of party-based Euroscepticism across Europe. It draws on data from expert surveys with qualitative data to outline the way in which we can empirically see the link between the impacts of the crises in European states, and how far, and in what ways, Euroscepticism has been mobilized by political parties in those states. It identifies four main frames through which the EU is contested in European states which focus on: economic factors, immigration, democracy/sovereignty and national factors. It also shows that there has been a clear difference between the impacts of the different crises. While the Eurozone crisis had a particularly powerful effect in the party systems of those countries most affected by the bailout packages and the migration crisis had a particularly strong effect on party politics in the post-communist states of central Europe, Brexit has had a very limited impact on national party politics, although this may change in the longer-term
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
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
Does the information source matter? Newspaper readership, political preferences and attitudes towards the European Union in the United Kingdom, France and the Netherlands
Previous research has indicated that political radicals and cynics tend to obtain information from like-minded media sources. In this study, we relate media use to political preferences by utilising a cross-national large-N data set collected during the European elections in 2014 through an online opt-in sample and the European Election Studies (EES), in order to test whether individuals who are negatively opinionated towards the EU and the political elite get informed via media that have a similar attitude towards the EU and politics. Our findings indicate that Eurosceptic voters differ considerably from moderate and pro-European voters in terms of their daily media use. In addition, we find that getting informed via a left-wing- or a right-wing-oriented mainstream media matters, when explaining voter’s policy preference
Molecular Dynamics Model to Explore the Initial Stages of Anion Exchange involving Layered Double Hydroxide Particles
A classical molecular dynamics (MD) model of fully unconstrained layered double hydroxide (LDH) particles in aqueous NaCl solution was developed to explore the initial stages of the anion exchange process, a key feature of LDHs for their application in different fields. In particular, this study focuses on the active corrosion protection mechanism, where LDHs are able to entrap aggressive species from the solution while releasing fewer corrosive species or even corrosion inhibitors. With this purpose in mind, it was explored the release kinetics of the delivery of nitrate and 2-mercaptobenzothiazole (MBT, a typical corrosion inhibitor) from layered double hydroxide particles triggered by the presence of aggressive chloride anions in solution. It was shown that the delamination of the cationic layers occurs during the anion exchange process, which is especially evident in the case of MBT−
The Ti2CO2 MXene as a nucleobase 2D sensor: a first-principles study
MXenes are a recently discovered class of two-dimensional materials, which have been attracting much interest by virtue of their promising biomedical and electronic applications. Here, we report on the results of first-principles calculations, based on density functional theory (DFT) including dispersion, of the adsorption energies and configurations of the five nucleobases, molecules conforming nucleotides in nucleic acids, such as DNA and RNA, on the oxygen-terminated titanium carbide MXene surface (Ti2CO2), chosen as a prototype MXene due to titanium being the most biocompatible transition metal. We find that physisorption is the most likely mechanism of adsorption on the Ti2CO2 (0001) basal surface, with the molecules sitting parallel to the MXene, about 2.5 Ã… away. The calculated adsorption energies and Bader charge transfer values are moderate, as desired for sensing applications. We find a fair correlation between the adsorption energies and the van der Waals volumes of the nucleobases, hinting towards an adsorption dominated by van der Waals interactions. No structural deformation is observed on the molecules or on the surface. Thus, all of our conclusions support the potential applicability of the Ti2CO2 MXene as a suitable nucleobase sensor.publishe
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