The relationship between structure and corrosion inhibition of a series of 30 imidazol, benzimidazol, and pyridine derivatives has been established through the investigation of quantum descriptors ...calculated with PBE/6-311++G**. A quantitative structure–property relationship model was obtained by examination of these descriptors using a genetic functional approximation method based on a multiple linear regression analysis. Our results indicate that the efficiency of corrosion inhibitors is strongly associated with aromaticity, electron donor ability, and molecular volume descriptors. In order to calibrate and validate the proposed model, we performed electrochemical impedance spectroscopy (EIS) studies on imidazole, 2-methylimidazole, benzimidazole, 2-chloromethylbenzimidazole, pyridine, and 2-aminopyridine compounds. The experimental values for efficiency of corrosion inhibition are in good agreement with the estimated values obtained by our model, thus confirming that our approach represents a promising and suitable tool to predict the inhibition of corrosion attributes of nitrogen containing heterocyclic compounds. The adsorption behavior of imidazole or benzimidazole heterocyclic molecules on the Fe(110) surface was also studied to elucidate the inhibition mechanism; the aromaticity played an important role in the adsorbate–surface complex.
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An asymmetric hydroarylative cyclization of enynes involving a C–H bond cleavage is reported. The cobalt-catalyzed cascade generates three new bonds in an atom-economical fashion. The products were ...obtained in excellent yields and excellent enantioselectivities as single diastereo- and regioisomers. Preliminary mechanistic studies indicate that the reaction shows no intermolecular C–H crossover. This work highlights the potential of cobalt catalysis in C–H bond functionalization and enantioselective domino reactivity.
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The hypothesis that Neanderthals exploited birds for the use of their feathers or claws as personal ornaments in symbolic behaviour is revolutionary as it assigns unprecedented cognitive abilities to ...these hominins. This inference, however, is based on modest faunal samples and thus may not represent a regular or systematic behaviour. Here we address this issue by looking for evidence of such behaviour across a large temporal and geographical framework. Our analyses try to answer four main questions: 1) does a Neanderthal to raptor-corvid connection exist at a large scale, thus avoiding associations that might be regarded as local in space or time?; 2) did Middle (associated with Neanderthals) and Upper Palaeolithic (associated with modern humans) sites contain a greater range of these species than Late Pleistocene paleontological sites?; 3) is there a taphonomic association between Neanderthals and corvids-raptors at Middle Palaeolithic sites on Gibraltar, specifically Gorham's, Vanguard and Ibex Caves? and; 4) was the extraction of wing feathers a local phenomenon exclusive to the Neanderthals at these sites or was it a geographically wider phenomenon?. We compiled a database of 1699 Pleistocene Palearctic sites based on fossil bird sites. We also compiled a taphonomical database from the Middle Palaeolithic assemblages of Gibraltar. We establish a clear, previously unknown and widespread, association between Neanderthals, raptors and corvids. We show that the association involved the direct intervention of Neanderthals on the bones of these birds, which we interpret as evidence of extraction of large flight feathers. The large number of bones, the variety of species processed and the different temporal periods when the behaviour is observed, indicate that this was a systematic, geographically and temporally broad, activity that the Neanderthals undertook. Our results, providing clear evidence that Neanderthal cognitive capacities were comparable to those of Modern Humans, constitute a major advance in the study of human evolution.
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This Invited Commentary explores disparities in academic medicine, known as the minority tax, through the careers of 2 men in senior positions, who are underrepresented minorities in medicine ...(URMMs), with the goal of sharing real-world experiences that other URMM faculty can use to their benefit. The authors use their lived experiences to document the realities of various aspects of the minority tax (i.e., isolation, mentorship, diversity efforts, and clinical assignments) and introduce a new aspect of the minority tax that has affected both of their inner decision-making processes and personal ambitionsthe gratitude tax. By sharing these experiences, the authors are also able to recognize individual mentors and sponsors as well as changes in their knowledge, skills, and attitudes that affected their ability to accomplish career goals, leading to their current academic positions. Sharing experiences is a meaningful way of providing examples for other URMM faculty to follow, as well as illustrating ways in which senior leadership can help mitigate the effect of the minority tax on URMM faculty, thereby increasing equity in academic medicine.
Electron crystallography has a storied history which rivals that of its more established X-ray-enabled counterpart. Recent advances in data collection and analysis have sparked a renaissance in the ...field, opening a new chapter for this venerable technique. Burgeoning interest in electron crystallography has spawned innovative methods described by various interchangeable labels (3D ED, MicroED, cRED, etc.). This Review covers concepts and findings relevant to the practicing crystallographer, with an emphasis on experiments aimed at using electron diffraction to elucidate the atomic structure of three-dimensional molecular crystals.
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6.
Overview of Multi-MW Wind Turbines and Wind Parks Liserre, Marco; Cárdenas, Roberto; Molinas, Marta ...
IEEE transactions on industrial electronics (1982),
2011-April, 2011-04-00, 20110401, Volume:
58, Issue:
4
Journal Article
Peer reviewed
Multimegawatt wind-turbine systems, often organized in a wind park, are the backbone of the power generation based on renewable-energy systems. This paper reviews the most-adopted wind-turbine ...systems, the adopted generators, the topologies of the converters, the generator control and grid connection issues, as well as their arrangement in wind parks.
Candida auris is an emerging multidrug-resistant fungus that causes a wide range of symptoms. We report finding 17 cases of C. auris infection that were originally misclassified but correctly ...identified 27.5 days later on average. Patients with a delayed diagnosis of C. auris had a 30-day mortality rate of 35.2%.
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Field oriented control (FOC), direct torque control (DTC) and finite set model predictive control (FS-MPC) are different strategies for high performance electrical drive systems. FOC uses linear ...controllers and pulse width modulation (PWM) to control the fundamental components of the load voltages. On the other hand, DTC and FS-MPC are nonlinear strategies that generate directly the voltage vectors in the absence of a modulator. This paper presents all three methods starting from theoretic operating principles, control structures and implementation. Experimental assessment is performed to discuss their advantages and limitations in detail. As main conclusions of this work, it is affirmed that different strategies have their own merits and all meet the requirements of modern high performance drives.
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A palladium-catalyzed intramolecular carbopalladation, intramolecular C–H bond activation, and alkyne insertion sequence for the generation of dihydrobenzoindolones is described. Products are ...obtained in moderate to excellent yields as single regioisomers. Various functional groups on both reaction partners were tolerated, and the scalability of this method was determined.
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•Different functional groups in imidazole inhibitors modify the corrosion behavior.•Molecular properties can be associated to corrosion inhibition efficiency.•Theoretical model ...predicts experimental results adequately.
The corrosion inhibition efficiency of carbon steel was evaluated using fifteen molecules derivated from imidazole and benzimidazole in 1.0M HCl. The inhibition efficiency varies from 15.6 to 89.4%, depending on the chemical and the electronic structure of the compounds. The structural properties of the molecules under study were determined by density functional theory. Experimental and theoretical parameters were used to construct a model to predict the inhibition observed. The proposed model shows that inhibition efficiency is related to the molecule volume, charge, electronegativity, and aromaticity. The model is successfully used to predict the corrosion behavior of two additional molecules.
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