Probing the electronic properties and charge state of gold nanoparticles on ultrathin MgO versus thick doped CaO films

Electron transfer into metal nanoparticles on oxide supports is associated with unusual morphological, electronic, and chemical properties of the charged system. Two fundamental charging routes have been identified so far, which are electron tunneling through ultrathin oxide films supported by a bulk metal and charge donation from single-ion impurities embedded in the oxide matrix. In this study, we have investigated whether both routes lead to the formation of metal deposits with identical properties. For this purpose, Au islands have been prepared on 1−2ML thin MgO/Ag(001) layers and on 25-ML-thick CaO films doped with Mo impurities. The morphological and electronic properties of the islands were analyzed with low-temperature scanning tunneling microscopy (STM) and spectroscopy. In both systems, pronounced electron confinement effects are observed in the nanostructures, arising from the quantization of one and the same Au electronic band. Moreover, clear experimental signatures for a charge transfer into the islands are found, such as a layer-by-layer growth of the ad-metal and a negative contrast of the oxide region around the deposits in STM images. Our data provide evidence that the charged nanostructures exhibit comparable properties independent of the origin of the extra electrons. This agreement suggests that ultrathin oxide films may be used as model systems for doped bulk oxides, as used in heterogeneous catalysis

Control of Diffuse Vacuum Arc Using Axial Magnetic Fields in Commercial High Voltage Switchgear

During the development of a commercial vacuum interrupter for application in HV (high voltage) switchgear at a rated voltage of 145kV, we investigated the behavior of vacuum arcs controlled by axial magnetic fields (AMF). AMF arc control is already extensively used in medium voltage (1-52kV) applications, the key difference is the 2-3 times larger contact gap and the corresponding reduction of the AMF strength for HV applications. We conducted several stress tests with short circuit currents up to 40kA, thus not only testing the interrupting capability, but also the electrical endurance of such a contact system. We also investigated the dielectric behavior of the vacuum interrupter by testing the capacitive switching duty. Overall, the contacts were used in about 40 operations at high currents. Despite this large number of operations, they showed a minimal amount of contact erosion and damage and demonstrated behavior very similar to the extensive experience with MV vacuum interrupters. In line with simulation results, we conclude that even at high contact gaps and currents, a diffuse vacuum arc was maintained which distributed the arc energy evenly over the contacts

Evolution of the electronic structure of CaO thin films following Mo interdiffusion at high temperature

The electronic structure of CaO films of 10–60 monolayer thickness grown on Mo(001) has been investigated with synchrotron-mediated x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Upon annealing or reducing the thickness of the film, a rigid shift of the CaO bands to lower energy is revealed. This evolution is explained with a temperature-induced diffusion of Mo ions from the metal substrate to the oxide and their accumulation in the interface region of the film. The Mo substitutes divalent Ca species in the rocksalt lattice and is able to release electrons to the system. The subsequent changes in the Mo oxidation state have been followed with high-resolution XPS measurements. While near-interface Mo transfers extra electrons back to the substrate, generating an interface dipole that gives rise to the observed band shift, near-surface species are able to exchange electrons with adsorbates bound to the oxide surface. For example, exposure of O2 results in the formation of superoxo species on the oxide surface, as revealed from STM measurements. Mo interdiffusion is therefore responsible for the pronounced donor character of the initially inert oxide, and largely modifies its adsorption and reactivity behavior

The Potential Impact of Heparanase Activity and Endothelial Damage in COVID-19 Disease

SARS-CoV-2 was first detected in 2019 in Wuhan, China. It has been found to be the most pathogenic virus among coronaviruses and is associated with endothelial damage resulting in respiratory failure. Determine whether heparanase and heparan sulfate fragments, biomarkers of endothelial function, can assist in the risk stratification and clinical management of critically ill COVID-19 patients admitted to the intensive care unit. We investigated 53 critically ill patients with severe COVID-19 admitted between March and April 2020 to the University Hospital RWTH Aachen. Heparanase activity and serum levels of both heparanase and heparan sulfate were measured on day one (day of diagnosis) and day three in patients with COVID-19. The patients were classified into four groups according to the severity of ARDS. When compared to baseline data (day one), heparanase activity increased and the heparan sulfate serum levels decreased with increasing severity of ARDS. The heparanase activity significantly correlated with the lactate concentration on day one (r = 0.34, p = 0.024) and on day three (r = 0.43, p = 0.006). Heparanase activity and heparan sulfate levels correlate with COVID-19 disease severity and outcome. Both biomarkers might be helpful in predicting clinical course and outcomes in COVID-19 patients

Sequestration of defenses against predators drives specialized host plant associations in preadapted milkweed bugs (Heteroptera: Lygaeinae)

AbstractHost plant specialization across herbivorous insects varies dramatically, but while the molecular mechanisms of host plant adaptations are increasingly known, we often lack a comprehensive understanding of the selective forces that favor specialization. The milkweed bugs (Heteroptera: Lygaeinae) are ancestrally associated with plants of the Apocynaceae from which they commonly sequester cardiac glycosides for defense, facilitated by resistant NaNa+/K+-ATPases and adaptations for transport, storage, and discharge of toxins. Here, we show that three Lygaeinae species independently colonized four novel nonapocynaceous hosts that convergently produce cardiac glycosides. A fourth species shifted to a new source of toxins by tolerating and sequestering alkaloids from meadow saffron (Colchicum autumnale, Colchicaceae). Across three milkweed bug species tested, feeding on seeds containing toxins did not improve growth or speed of development and even impaired growth and development in two species, but sequestration mediated protection of milkweed bugs against two natural predators: lacewing larvae and passerine birds. We conclude that physiological preadaptations and convergent phytochemistry facilitated novel specialized host associations. Since toxic seeds did not improve growth but either impaired growth or, at most, had neutral effects, selection by predators on sequestration of defenses, rather than the exploitation of additional profitable dietary resources, can lead to obligatory specialized host associations in otherwise generalist insects

An advanced risk analysis approach for container port safety evaluation

Risk analysis in seaports plays an increasingly important role in ensuring port operation reliability, maritime transportation safety and supply chain distribution resilience. However, the task is not straightforward given the challenges, including that port safety is affected by multiple factors related to design, installation, operation and maintenance and that traditional risk assessment methods such as quantitative risk analysis cannot sufficiently address uncertainty in failure data. This paper develops an advanced Failure Mode and Effects Analysis (FMEA) approach through incorporating Fuzzy Rule-Based Bayesian Networks (FRBN) to evaluate the criticality of the hazardous events (HEs) in a container terminal. The rational use of the Degrees of Belief (DoB) in a fuzzy rule base (FRB) facilitates the implementation of the new method in Container Terminal Risk Evaluation (CTRE) in practice. Compared to conventional FMEA methods, the new approach integrates FRB and BN in a complementary manner, in which the former provides a realistic and flexible way to describe input failure information while the latter allows easy updating of risk estimation results and facilitates real-time safety evaluation and dynamic risk-based decision support in container terminals. The proposed approach can also be tailored for wider application in other engineering and management systems, especially when instant risk ranking is required by the stakeholders to measure, predict and improve their system safety and reliability performance

Ribonuclease 1 attenuates septic cardiomyopathy and cardiac apoptosis in a murine model of polymicrobial sepsis.

Septic cardiomyopathy is a life-threatening organ dysfunction caused by sepsis. Ribonuclease 1 (RNase 1) belongs to a group of host-defense peptides that specifically cleave extracellular RNA (eRNA). The activity of RNase1 is inhibited by ribonuclease-inhibitor 1 (RNH1). The role of RNase 1 in septic cardiomyopathy and associated cardiac apoptosis, however, is completely unknown. Here, we showed that sepsis resulted in a significant increase in RNH1 and eRNA serum levels compared to those of healthy subjects (p < 0.05). Treatment with RNase 1 resulted in a significant decrease of apoptosis, induced by the intrinsic pathway, and TNF expression in murine cardiomyocytes exposed to either necrotic cardiomyocytes or serum of septic patients for 16 h (p < 0.05). Furthermore, treatment of septic mice with RNase 1 resulted in a reduction in cardiac apoptosis, TNF expression and septic cardiomyopathy (p < 0.05). These data demonstrate that eRNA plays a crucial role in the pathophysiology of the organ (cardiac) dysfunction in sepsis and RNase and RNH1 may be new therapeutic targets/strategies to reduce the cardiac injury and dysfunction caused by sepsis

Inhibition of Macrophage Migration Inhibitory Factor Activity Attenuates Haemorrhagic Shock-Induced Multiple Organ Dysfunction in Rats

OBJECTIVE: The aim of this study was to investigate (a) macrophage migration inhibitory factor (MIF) levels in polytrauma patients and rats after haemorrhagic shock (HS), (b) the potential of the MIF inhibitor ISO-1 to reduce multiple organ dysfunction syndrome (MODS) in acute (short-term and long-term follow-up) HS rat models and (c) whether treatment with ISO-1 attenuates NF-κB and NLRP3 activation in HS. BACKGROUND: The MODS caused by an excessive systemic inflammatory response following trauma is associated with a high morbidity and mortality. MIF is a pleiotropic cytokine which can modulate the inflammatory response, however, its role in trauma is unknown. METHODS: The MIF levels in plasma of polytrauma patients and serum of rats with HS were measured by ELISA. Acute HS rat models were performed to determine the influence of ISO-1 on MODS. The activation of NF-κB and NLRP3 pathways were analysed by western blot in the kidney and liver. RESULTS: We demonstrated that (a) MIF levels are increased in polytrauma patients on arrival to the emergency room and in rats after HS, (b) HS caused organ injury and/or dysfunction and hypotension (post-resuscitation) in rats, while (c) treatment of HS-rats with ISO-1 attenuated the organ injury and dysfunction in acute HS models and (d) reduced the activation of NF-κB and NLRP3 pathways in the kidney and liver. CONCLUSION: Our results point to a role of MIF in the pathophysiology of trauma-induced organ injury and dysfunction and indicate that MIF inhibitors may be used as a potential therapeutic approach for MODS after trauma and/or haemorrhage

Configuration-interaction calculations of PsH and e(+)Be

The configuration-interaction (CI) method is applied to the study of the positronium-hydride (PsH) and positronic-beryllium (e+Be) systems. The binding energy and other properties are slowly convergent with respect to the angular momentum of the orbitals used to construct the CI basis states. The largest calculations recover 94% and 80% of the binding energy against dissociation when compared with existing calculations of PsH and e+ Be. Extrapolating using Cl convergence trends improves these results to 99% and 98%, respectively. Convergence is not so good for the electron-positron annihilation rates, but the extrapolated annihilation rates were within 10% of the best calculations. Two different schemes have been used to construct the CI basis, and it is found that it is possible to discard roughly half the CI basis with almost no degradation in the binding energy and the annihilation rate. These investigations demonstrate the feasibility of using single particle orbitals centred on the nucleus to represent positronic systems with two valence electrons