Understanding the nature of the interaction at the graphene/metal interfaces is the basis for graphene-based electron- and spin-transport devices. Here we investigate the hybridization between ...graphene- and metal-derived electronic states by studying the changes induced through intercalation of a pseudomorphic monolayer of Cu in between graphene and Ir(111), using scanning tunnelling microscopy and photoelectron spectroscopy in combination with density functional theory calculations. We observe the modifications in the band structure by the intercalation process and its concomitant changes in the charge distribution at the interface. Through a state-selective analysis of band hybridization, we are able to determine their contributions to the valence band of graphene giving rise to the gap opening. Our methodology reveals the mechanisms that are responsible for the modification of the electronic structure of graphene at the Dirac point, and permits to predict the electronic structure of other graphene-metal interfaces.
Single-photon laser-enabled Auger decay (spLEAD) is predicted theoretically B. Cooper and V. Averbukh, Phys. Rev. Lett. 111, 083004 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.083004 and here we ...report its first experimental observation in neon. Using coherent, bichromatic free-electron laser pulses, we detect the process and coherently control the angular distribution of the emitted electrons by varying the phase difference between the two laser fields. Since spLEAD is highly sensitive to electron correlation, this is a promising method for probing both correlation and ultrafast hole migration in more complex systems.
Using transmission electron microscopy, tension and indentation tests we studied commercially pure aluminum processed by severe plastic deformation through accumulative roll bonding (ARB Al) and ...equal-channel angular pressing (ECAP Al) up to 8.0 von Mises equivalent strain to find the structural features providing improved mechanical properties and their enhanced thermal stability in the former case. It is revealed that the average size of the elements of the grain-subgrain structure is 23% lower and the strength properties are 19 – 27% higher in ARB Al with respect to ECAP Al. The physical reason for more refinement of the grain-subgrain structure and enhanced mechanical properties is the presence of dispersed alumina nanoparticles introduced into the bulk of ARB aluminum from the surface of the bonded stripes during ARB. The thermal stability of microhardness of ARB Al exceeds the respective value of ECAP Al in the temperature interval of 473 – 513 К, where the recrystallization starts to occur. The improved thermal stability of ARB Al is related to the higher resistance to recrystallization due to the presence of alumina nanoparticles on grain boundaries formed during ARB and precipitation of Si from the solid solution on these nanoparticles.
Abstract Background There are two main methods used for transcatheter aortic valve replacement (TAVR) FEA modeling for medical devices development: patient specific and general approaches. Advantages ...and disadvantages of both approaches have never been compared in a single study. Method Here we propose a bioinformatic algorithm to evaluate the accuracy of patient specific and generalized FEA approaches with regards to proximity configuration of the implanted stent reconstructed by computed tomography. In addition, in this study we also assessed the impact of the level of detail on FEA accuracy in the patient specific approach. Results Our results demonstrate that in certain cases, the generalized approach can ensure the same accuracy as the patient specific approach. Therefore, considering high cost effectiveness of the generalized approach, we identify it as more feasible in the context of TAVR. Furthermore, we suggest that high level of detail can improve the reproducibility of modeling results in the patient specific approach. Conclusions Our findings may help medical engineers to better understand the peculiarities of both approaches and therefore make the right decision when choosing a particular approach for computer modeling. Future studies are required to validate our observations.
The possibility of using radiation from a two-frequency pulsed copper vapor laser with wavelengths of 510.6 and 578.2 nm with an exposure of 30 to 120 s to stimulate the development of coniferous ...trees (spruce, pine, larch) with single seed irradiation is shown. The stimulation effect manifests itself at various early stages of development, such as the awakening of seeds in the aquatic environment in the first hours of the experiment (according to the electron absorption spectroscopy data), seed germination, and seedling growth under stressful cultivation conditions. Possible causes of light exposure to plant seeds are discussed.
Huntington’s disease is a hereditary incurable neurodegenerative disease caused by expansion of the polyglutamine tract in exon 1 of the huntingtin gene. Huntingtin is a large protein involved in ...many cellular processes, such as division, transport and secretion. Mutations in the protein lead to disruption of many cellular processes, including secretion, but differences in the composition of the secretome of cells in normal conditions and in Huntington’s disease remain poorly studied. Since huntingtin is expressed at high levels in peripheral tissues and in the skin, we have focused our attention on the study of secretome produced by dermal fibroblasts. In order to identify differences in secreted factors caused by the huntingtin mutation we used tandem time-of-flight mass spectrometry. Forty-two differential proteins were identified in the secretomes of dermal fibroblasts from healthy donor and patient with Huntington’s disease. We examine several proteins of interest including filamin A, periostin, ACTN4, BASP1, adrenomedullin, HSP70 and 14-3-3, whose expression is associated with processes such as cytoskeletal organization, cell adhesion, proliferation, cell migration, protein binding and regulation of cytoskeletal structure. HSP70 and 14-3-3 have neuroprotective properties, and interestingly, their expression was not detected in the secretome of cells with Huntington’s disease. Thus, it was shown that the set of proteins secreted into the extracellular space by dermal fibroblasts with the Huntington’s disease genotype differs from healthy cells, and the differences in cellular processes (proliferation, migration) observed in these cells in vitro are probably due to differences in the composition of the extracellular matrix which they synthesize.
Using the new electrodeless microwave technology for generating plasma in an open atmosphere, solutions of hydrogen peroxide and nitrogen compounds are obtained from distilled water. The method is ...based on the activation of distilled water by a jet of thermal argon plasma of an electrodeless microwave discharge in air at atmospheric pressure. Plasma-activated water has a stimulating effect on seed germination and plant growth, which is much more effective than the effect of industrial hydrogen peroxide solutions with stabilizing additives.
This paper describes an approach based on machine learning technology that is of particular interest for the localization and characterization of both single focal stenoses and multivessel multifocal ...lesions. Due to the complexity of analyzing large amounts of data for the cardiac surgeon, we pay special attention to the analysis, training, and comparison of popular neural networks that classify and localize foci of stenosis on coronary angiography data. From the complete coronarography dataset collected at the Research Institute for Complex Issues of Cardiovascular Diseases, we retrospectively select data of 100 patients. For the automated analysis of the medical data, the paper considers in detail three models (SSD MobileNet V1, Faster-RCNN ResNet-50 V1, and Faster-RCNN NASNet), which differ in their architecture, complexity, and the number of weights. The models are compared in terms of their basic efficiency characteristics: accuracy, training time, and prediction time. The test results show that the training and prediction times are directly proportional to the complexity of the models. In this regard, Faster-RCNN NASNet exhibits the lowest prediction time (the average processing time for one image is 880 ms), while Faster-RCNN ResNet-50 V1 has the highest prediction accuracy. The latter model reaches the mean average precision (mAP) level of 0.92 on the validation dataset. On the other hand, SSD MobileNet V1 is the fastest model, capable of making predictions with a prediction rate of 23 fps.
—
Bioprosthetic heart valves (BHVs) have lower thrombogenicity rates and excellent hemodynamic parameters similar to native valves. However, the lifespan of these medical devices is limited to 15 ...years due to the structural valve degeneration (SVD). One of the mechanisms underlying functional impairment and calcification of BHVs includes proteolytic degradation of biomaterials. However, proteases found in xenogeneic tissue of BHVs remain poorly studied. In this study using the dot blot assay, we have performed a screening analysis of proteolytic enzymes and their inhibitors in the leaflets of five BHVs explanted due to dysfunction. Five aortic valves (AVs) explanted due to calcific aortic valve disease were used as a comparison group. The results of the study have demonstrated the presence of at least 17 proteases and 19 of their inhibitors in BHVs. In the AVs 20 proteases and 21 of their inhibitors were identified. Small quantitative differences were found between proteomic profiles of BHVs and AVs. Matrix metalloproteinases (MMPs) were expressed in BHVs and AVs at comparable levels, but the level of tissue inhibitors of metalloproteinases-1/-2 and reversion-inducing-cysteine-rich protein with Kazal motifs in implant tissues was lower than in native valves. This suggests that excessive activity of MMPs cannot be counterbalanced by their specific inhibitors in BHVs and therefore MMPs initiate the process of degeneration. Moreover, the detection of a wide range of proteolytic enzymes and their inhibitors in the degenerated BHVs suggests the existence of several pathophysiological pathways that can lead to SVD.
Calcific aortic valve stenosis (CAVS) is a serious socio-economic problem in developed countries because this disease is the most common indication for aortic valve replacement. Currently, there are ...no methods for non-invasive treatment of CAVS. Nevertheless, it is assumed that effective drug therapy for CAVS can be developed on the basis of modulators of the renin-angiotensin-aldosterone system (RAAS), which is involved in the pathogenesis of this disease. The purpose of this paper is to compile and analyze current information on the role of RAAS in the CAVS pathophysiology. Recent data on the effectiveness of RAAS inhibition are reviewed.
PDF
