Wafer-scale single-orientation 2D layers by atomic edge-guided epitaxial growth

We provide a systematic summary of the critical factors—including crystal/substrate symmetry and energy consideration—necessary for synthesizing single-orientation 2D layers.

Mechanical Properties And Joining Mechanism of Magnetic Pulse Welded Aluminum To Titanium

Magnetic pulse welding of dissimilar aluminum and titanium was investigated to optimize process parameters in terms of discharge voltage, radial gap and overlapping length. Moreover, impacting modes at different overlapping lengths were discussed. The joining mechanism was analyzed from aspects of microstructure, composition and hardness distribution. The shear strength increased with increasing discharge voltages, whereas shear strength decreased at first and then increased with the increasing radial gap, which has a more significant influence on shear strength than discharge voltage. Three impacting modes were proposed as bidirectional impacting, overall impacting and single-orientation impacting. However, the single-orientation impacting mode has the highest effective joining ratio. The welded joints were divided into four transition layer interfaces: continuous transition zone, transition zone with cracks, intermittent transition zone, and non-transition zone. Waves and intermetallic compounds are the two characteristics of the Al-Ti joint welded by magnetic pulse welding. The metal's hardness near the joint surface is higher than that of the base metal. In addition, Al3Ti and aluminum base metal were found in the transition layer of the joint.

Double Crystallization and Phase Separation in Polyethylene—Syndiotactic Polypropylene Di-Block Copolymers

Crystallization and phase separation in the melt in semicrystalline block copolymers (BCPs) compete in defining the final solid state structure and morphology. In crystalline–crystalline di-block copolymers the sequence of crystallization of the two blocks plays a definitive role. In this work we show that the use of epitaxial crystallization on selected crystalline substrates allows achieving of a control over the crystallization of the blocks by inducing crystal orientations of the different crystalline phases and a final control over the global morphology. A sample of polyethylene-block-syndiotactic polypropylene (PE-b-sPP) block copolymers has been synthesized with a stereoselective living organometallic catalyst and epitaxially crystallized onto crystals of two different crystalline substrates, p-terphenyl (3Ph) and benzoic acid (BA). The epitaxial crystallization on both substrates produces formation of highly ordered morphologies with crystalline lamellae of sPP and PE highly oriented along one direction. However, the epitaxial crystallization onto 3Ph should generate a single orientation of sPP crystalline lamellae highly aligned along one direction and a double orientation of PE lamellae, whereas BA crystals should induce high orientation of only PE crystalline lamellae. Thanks to the use of the two selective substrates, the final morphology reveals the sequence of crystallization events during cooling from the melt and what is the dominant event that drives the final morphology. The observed single orientation of both crystalline PE and sPP phases on both substrates, indeed, indicates that sPP crystallizes first onto 3Ph defining the overall morphology and PE crystallizes after sPP in the confined interlamellar sPP regions. Instead, PE crystallizes first onto BA defining the overall morphology and sPP crystallizes after PE in the confined interlamellar PE regions. This allows for discriminating between the different crystalline phases and defining the final morphology, which depends on which polymer block crystallizes first on the substrate. This work also shows that the use of epitaxial crystallization and the choice of suitable substrate offer a means to produce oriented nanostructures and morphologies of block copolymers depending on the composition and the substrates.

Single-orientation Quantitative Susceptibility Mapping identifies the Ventral Intermediate Nucleus of the Thalamus

Introduction: The ventral intermediate nucleus (VIM) represents the primary target in the treatment of tremor. Accurate localization is extremely important given its proximity to other thalamic nuclei. We utilized single orientation quantitative susceptibility mapping (QSM) at 3T to directly visualize the VIM. Methods: Four adult volunteers, one adult cadaver, and an essential tremor patient were scanned on a 3T MRI using a multi-echo gradient echo sequence. QSM images were generated using the improved sparse linear equation and least-squares (iLSQR) algorithm. Two adult subjects underwent multiple head orientation imaging for multi-orientation QSM reconstruction. The VIM was prospectively identified with direct visualization as well as indirect landmark-based localization. Results: The bilateral VIM was consistently identified as a hypointense structure within the lateral thalamus, appearing similar on multi-orientation and single-orientation QSM, corresponding to the myelinated dentatorubrothalamic tract (DRTT). The indirect method resulted in a comparatively inferomedial localization, at times missing the VIM and DRTT. Conclusion: Single-orientation QSM offers a clinically feasible, non-invasive imaging-based approach to directly localize the VIM.

USE OF CONVOLUTIONAL NEURAL NETWORKS FOR X-RAY IMAGE ORIENTATION DETERMINATION

The fact that Artificial Intelligence (AI) based algorithms exhibit a high performance on image classification tasks has been shown many times. Still, certain issues exist with the application of machine learning (ML) artificial neural network (ANN) algorithms. The best known is the need for a large amount of statistically varied data, which can be addressed with expanded collection or data augmentation. Other issues are also present. Convolutional neural networks (CNNs) show extremely high performance on image-shaped data. Despite their performance, CNNs exhibit a large issue which is the sensitivity to image orientation. Previous research shows that varying the orientation of images may greatly lower the performance of the trained CNN. This is especially problematic in certain applications, such as X-ray radiography, an example of which is presented here. Previous research shows that the performance of CNNs is higher when used on images in a single orientation (left or right), as opposed to the combination of both. This means that the data needs to be differentiated before it enters the classification model. In this paper, the CNN-based model for differentiation between left and right-oriented images is presented. Multiple CNNs are trained and tested, with the highest performing being the VGG16 architecture which achieved an Accuracy of 0.99 (+/- 0.01), and an AUC of 0.98 (+/- 0.01). These results show that CNNs can be used to address the issue of orientation sensitivity by splitting the data in advance of being used in classification models.

Образование полуполярных III-нитридных слоев на поверхности Si(100), структурированной с помощью самоформирующейся наномаски

The epitaxial growth of AlN and GaN layers was studied by Metalorganic Vapor Phase Epitaxy, on a Si(100) substrate, on the surface of which a V-shaped nanostructure with sub-100 nm element size (NP-Si(100)) was formed. It is shown that a corrugated surface is formed from semipolar AlN(10-11) planes with opposite "c"axes during the formation of a semipolar AlN layer at the initial stage of epitaxy. Then, during the growth of the GaN layer, the transition from the symmetric state of two semipolar AlN planes to an asymmetric state with a single orientation of the "c"-axis of the semipolar GaN(10-11) layer occurs, and the "c" direction in the growing semipolar layer coincides with the direction of the flow of N2+ ions to the silicon surface during the formation of a nanomask.

Transitional Channel Flow: A Minimal Stochastic Model

In line with Pomeau’s conjecture about the relevance of directed percolation (DP) to turbulence onset/decay in wall-bounded flows, we propose a minimal stochastic model dedicated to the interpretation of the spatially intermittent regimes observed in channel flow before its return to laminar flow. Numerical simulations show that a regime with bands obliquely drifting in two stream-wise symmetrical directions bifurcates into an asymmetrical regime, before ultimately decaying to laminar flow. The model is expressed in terms of a probabilistic cellular automaton of evolving von Neumann neighborhoods with probabilities educed from a close examination of simulation results. It implements band propagation and the two main local processes: longitudinal splitting involving bands with the same orientation, and transversal splitting giving birth to a daughter band with an orientation opposite to that of its mother. The ultimate decay stage observed to display one-dimensional DP properties in a two-dimensional geometry is interpreted as resulting from the irrelevance of lateral spreading in the single-orientation regime. The model also reproduces the bifurcation restoring the symmetry upon variation of the probability attached to transversal splitting, which opens the way to a study of the critical properties of that bifurcation, in analogy with thermodynamic phase transitions.

The nature and potential of the synergistic effects of management in a communicative society

The article raises the problem of self-organization for a communicatively organized society, which today is being addressed in the context of synergetics. Communication combines cognitive experience, a system of values, practical experience - all that is the basis for the consistent achievement of the ideal goal of self-development. In the classical theory of social knowledge, history has the image of a linear process, represented through a single orientation, through the repetition of processes. Having examined in detail the approach proposed by N. Luman, which describes the use of the possibilities of synergetics in creating the theory of society, many unique concepts are opened for research, such as "autopoiesis", "operational closure", and "structural docking". Having revealed the definitions of the above, the article defines the role and potential of synergetics in management, discloses those innovations that are introduced into the management model of the synergetic approach.