Mitigation of hydrogen embrittlement by carbon monoxide impurity in gaseous H2

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Tailoring the work function of graphene via defects, nitrogen-doping and hydrogenation : a first principles study

The effect of defects, nitrogen doping, and hydrogen saturation on the work function of graphene is investigated via first principle calculations. Whilst Stone–Wales defects have little effect, single and double vacancy defects increase the work function by decreasing charge density in the π-electron system. Substitutional nitrogen doping in defect-free graphene significantly decreases the work function, because the nitrogen atoms donate electrons to the π-electron system. In the presence of defects, these competing effects mean that higher nitrogen content is required to achieve similar reduction in work function as for crystalline graphene. Doping with pyridinic nitrogen atoms at vacancies slightly increases the work function, since pyridinic nitrogen does not contribute electrons to the π-electron system. Meanwhile, hydrogen saturation of the pyridinic nitrogen atoms significantly reduces the work function, due to a shift from pyridinic to graphitic-type behavior. These findings clearly explain some of the experimental work functions obtained for carbon and nitrogen-doped carbon materials in the literature, and has implications in applications such as photocatalysis, photovoltaics, electrochemistry, and electron field emission

A combined micromechanics/materials science approach to understanding high temperature hydrogen attack

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Lattice strain mapping of platinum nanoparticles on carbon and SnO2 supports

It is extremely important to understand the properties of supported metal nanoparticles at the atomic scale. In particular, visualizing the interaction between nanoparticle and support, as well as the strain distribution within the particle is highly desirable. Lattice strain can affect catalytic activity, and therefore strain engineering via e.g. synthesis of core-shell nanoparticles or compositional segregation has been intensively studied. However, substrate-induced lattice strain has yet to be visualized directly. In this study, platinum nanoparticles decorated on graphitized carbon or tin oxide supports are investigated using spherical aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM) coupled with geometric phase analysis (GPA). Local changes in lattice parameter are observed within the Pt nanoparticles and the strain distribution is mapped. This reveals that Pt nanoparticles on SnO 2 are more highly strained than on carbon, especially in the region of atomic steps in the SnO 2 lattice. These substrate-induced strain effects are also reproduced in density functional theory simulations, and related to catalytic oxygen reduction reaction activity. This study suggests that tailoring the catalytic activity of electrocatalyst nanoparticles via the strong metal-support interaction (SMSI) is possible. This technique also provides an experimental platform for improving our understanding of nanoparticles at the atomic scale

Myokardiale Deformationsbildgebung bei Patienten mit inflammatorischer Kardiomyopathie

Introduction: Inflammatory cardiomyopathy (iCM) is a major cause of dilated cardiomyopathy (DCM) and leading cause for heart transplantation. None of the routine noninvasive methods is reliable enough in establishing the diagnosis of iCM. Two-dimensional (2D) and three-dimensional (3D) speckle tracking echocardiography (STE) enable an accurate assessment of minor segmental alterations on myocardial contractility. The aim of our study was to assess the reliability and diagnostic accuracy of 2D and 3D STE in patients with endomyocardial biopsy-proven iCM. Methods: Two hundred fifty-five patients with suspected iCM on whom endomyocardial biopsies had been performed were included in the study. All of them underwent echocardiographic investigations and images of 2D longitudinal strain and strain rate measurements were recorded. In 57 patients 3D echocardiographic datasets were obtained and analyzed. According to the results of the histopathological and immunohistochemical analysis, the patients were classified into three groups: no myocardial inflammation, DCM and iCM. Results: In 57 patients no myocardial inflammation was detected, 60 patients were with DCM and 138 patients had iCM. 2D global longitudinal strain (GLS) was significantly attenuated in patients with iCM compared to the patients without myocardial inflammation (-14.50±5.40% vs. -18.39±4.05%, p<0.001), the same was observed for global systolic longitudinal strain rate (-0.92± 0.32 1/s, vs. -1.11±0.26 1/s, p<0.001) and global early diastolic longitudinal strain rate (1.16±0.45 1/s vs. 1.53±0.41 1/s, p<0.001). 3D GLS was significantly reduced in iCM patients compared to those without myocardial inflammation (-12.73±4.58% vs. -17.88±4.34%, p=0.003), global area strain (GAS), global circumferential strain (GCS) and global radial strain (GRS) were also significantly attenuated in patients with iCM compared to patients without myocardial inflammation (-22.09±7.46% vs. -30.01±6.12%, p=0.003; -13.22±4.53% vs. -17.39±3.84%, p=0.013; and 32.89±14.14% vs. 49.18±14.01%, p=0.002, respectively). STE parameters appeared highly predictive for detection of iCM. The 3D GRS showed the highest predictive values (area under the receiver operating curve of 0.793), followed by 3D GLS, GAS and GCS (area under the receiver operating curve of 0.790; 0.773 and 0.773, respectively). We found strong and significant correlations between 2D and 3D STE indexes and left ventricular (LV) ejection fraction, LV dimensions and volumes, maximal LV outflow tract velocity and tissue Doppler parameters. Conclusion: Our results showed that 2D and 3D STE indexes have the potential to facilitate early prediction of myocardial inflammation and could serve as useful noninvasive diagnostic tools.Einleitung: Die inflammatorische Kariomyopathie (iCM) ist eine wesentliche Ursache für eine dilatative Kardiomyopathie (DCM) und diese wiederum einer der häufigsten Gründe für eine Herztransplantation. Keine der routinemäßigen nicht-invasiven Untersuchungsmethoden ist zuverlässig genug, die Diagnose iCM zu stellen. Die zweidimensionale (2D) und dreidimensionale (3D) Speckle Tracking Echocardiographie (STE) ermöglichen eine präzise Beurteilung bereits geringer Veränderungen der myokardialen Kontraktilität. Ziel unserer Studie war es, die Zuverlässigkeit und die diagnostische Genauigkeit der 2D und 3D STE bei Patienten mit bioptisch nachgewiesener iCM zu bewerten. Methodik: 255 Patienten mit Verdacht auf iCM, bei denen Endomyokardbiopsien durchgeführt worden waren, wurden in die Studie eingeschlossen. Bei allen Patienten wurden Echokardiographien durchgeführt und Bilder für Messung von 2D longitudinalen Strain und Strain Rates gespeichert. Bei 57 Patienten wurden 3D Echokardiographiedatensätze aufgenommen und analysiert. Entsprechend der histopathologischen Befunde und der immunohistochemischen Analyse wurden die Patienten in drei Gruppen eingeteilt: keine Myokardinflammation, DCM und iCM. Ergebnisse: Bei 57 Patienten wurde keine Myokardinflammation nachgewiesen, bei 60 Patienten wurde eine DCM und bei 138 eine iCM nachgewiesen. 2D globaler longitudinaler Strain (GLS) war bei Patienten mit iCM im Vergleich zu Patienten ohne Myokardinflammation signifikant abgeschwächt (-14.50±5.40% vs. -18.39±4.05%, p<0.001), selbiges wurde auch für die globale systolische longitudinale Strain Rate (-0.92± 0.32 1/s, vs. -1.11±0.26 1/s, p<0.001) und die globale frühdiastolische longitudinale Strain Rate nachgewiesen (1.16±0.45 1/s vs. 1.53±0.41 1/s, p<0.001). 3D GLS war signifikant vermindert bei Patienten mit iCM verglichen mit Patienten ohne Myokardinflammation (-12.73±4.58% vs. -17.88±4.34%, p=0.003). Der globale area Strain (GAS), der globale zirkumferenzielle Strain (GCS) und der globale radiale Strain (GRS) waren auch bei Patienten mit iCM signifikant reduziert im Vergleich zu Patienten ohne Myokardinflammation (-22.09±7.46% vs. -30.01±6.12%, p=0.003; -13.22±4.53% vs. -17.39±3.84%, p=0.013 bzw. 32.89±14.14% vs. 49.18±14.01%, p=0.002). Die STE Parameter schienen für den Nachweis einer iCM hochprädiktiv zu sein. Der 3D GRS zeigte die höchsten prädiktiven Vorhersagewerte (Fläche unter der Receiver-Operating-Characteristic Kurve von 0.793), gefolgt von 3D GLS, GAS und GCS (Fläche unter der Receiver-Operating-Characteristic Kurve von 0.790; 0.773 bzw. 0.773). Wir fanden starke und signifikante Korrelationen zwischen den 2D und 3D STE Indizes und der linksventrikulären (LV) Ejektionsfraktion, LV-Dimensionen und Volumen, maximale LV- Ausflusstraktgeschwindigkeit und Gewebe Doppler Parametern. Schlussfolgerung: Unsere Ergebnisse zeigen, dass 2D und 3D STE Indizes das Potential haben, die frühe Vorhersage einer Myokardinflammation zu erleichtern und könnten als zusätzliche nicht-invasive diagnostische Untersuchungen dienen

Application of the non-equilibrium Green's function method in the design of nanoelectronic devices

Mathematics for Materials Science and Processin

Application of the non-equilibrium Green\u27s function method in the design of nanoelectronic devices

Mathematics for Materials Science and Processin