Direct photoluminescence probing of ferromagnetism in monolayer two-dimensional CrBr3

Atomically thin magnets are the key element to build up spintronics based on two-dimensional materials. The surface nature of two-dimensional ferromagnet opens up opportunities to improve the device performance efficiently. Here, we report the intrinsic ferromagnetism in atomically thin monolayer CrBr3, directly probed by polarization resolved magneto-photoluminescence. The spontaneous magnetization persists in monolayer CrBr3 with a Curie temperature of 34 K. The development of magnons by the thermal excitation is in line with the spin-wave theory. We attribute the layer-number dependent hysteresis loops in thick layers to the magnetic domain structures. As a stable monolayer material in air, CrBr3 provides a convenient platform for fundamental physics and pushes the potential applications of the two-dimensional ferromagnetism.Comment: 27 pages, 10 figure

Learning Multi-Level Information for Dialogue Response Selection by Highway Recurrent Transformer

With the increasing research interest in dialogue response generation, there is an emerging branch formulating this task as selecting next sentences, where given the partial dialogue contexts, the goal is to determine the most probable next sentence. Following the recent success of the Transformer model, this paper proposes (1) a new variant of attention mechanism based on multi-head attention, called highway attention, and (2) a recurrent model based on transformer and the proposed highway attention, so-called Highway Recurrent Transformer. Experiments on the response selection task in the seventh Dialog System Technology Challenge (DSTC7) show the capability of the proposed model of modeling both utterance-level and dialogue-level information; the effectiveness of each module is further analyzed as well

Enhancing Hydrogen Generation Through Nanoconfinement of Sensitizers and Catalysts in a Homogeneous Supramolecular Organic Framework.

Enrichment of molecular photosensitizers and catalysts in a confined nanospace is conducive for photocatalytic reactions due to improved photoexcited electron transfer from photosensitizers to catalysts. Herein, the self-assembly of a highly stable 3D supramolecular organic framework from a rigid bipyridine-derived tetrahedral monomer and cucurbit[8]uril in water, and its efficient and simultaneous intake of both [Ru(bpy)3 ]2+ -based photosensitizers and various polyoxometalates, that can take place at very low loading, are reported. The enrichment substantially increases the apparent concentration of both photosensitizer and catalyst in the interior of the framework, which leads to a recyclable, homogeneous, visible light-driven photocatalytic system with 110-fold increase of the turnover number for the hydrogen evolution reaction

Distributed Training Large-Scale Deep Architectures

Scale of data and scale of computation infrastructures together enable the current deep learning renaissance. However, training large-scale deep architectures demands both algorithmic improvement and careful system configuration. In this paper, we focus on employing the system approach to speed up large-scale training. Via lessons learned from our routine benchmarking effort, we first identify bottlenecks and overheads that hinter data parallelism. We then devise guidelines that help practitioners to configure an effective system and fine-tune parameters to achieve desired speedup. Specifically, we develop a procedure for setting minibatch size and choosing computation algorithms. We also derive lemmas for determining the quantity of key components such as the number of GPUs and parameter servers. Experiments and examples show that these guidelines help effectively speed up large-scale deep learning training

An in situ study on the coalescence of monolayer-protected Au-Ag nanoparticle deposits upon heating

The structural evolution of thiolate-protected nanoparticles of gold, silver, and their alloys with various Au/Ag ratios (3:1, 1:1, and 1:3) upon heating was investigated by means of in situ synchrotron radiation X-ray diffraction. The relationships between the coalescence and composition of nanoparticles, as well as the surfactant reactions, were clarified. Experimental results show that there existed a critical temperature ranging from 120°C to 164°C, above which the tiny broad X-ray diffraction peaks became sharp and strong due to particle coalescence. The coalescence temperatures for alloy nanoparticle deposits were clearly lower than those for pure metals, which can be ascribed to the rivalry between the thermodynamic effect due to alloying and the interactions between surface-assembled layers and the surface atoms of the nanoparticles. The strong affinity of thiolates to Ag and thus complex interactions give rise to a greater energy barrier for the coalescence of nanoparticles into the bulk and subsequent high coalescence temperature. The influences of particle coalescence on the optical and electrical properties of the nanoparticle deposits were also explored

Signal Integrity Analysis for High Speed Digital Circuit

This dissertation report marks the commencement of the Final Year Project (FYP) titled Signal Integrity Analysis for High Speed Digital Circuit. This project is a study on various signal integrity (SI) issues that could possibly come into play on Printed Circuit Boards (PCBs). This project is conducted to analyze and grasp a better understanding on the nature of the problem, how the problem is manifested in circuits and what design solutions can be employed to minimize its effects. Such a study is not something new but is definitely getting more crucial as the vast improvement in chip fabrication technology leads to logic families operating at a much higher speed, resulting to a faster rise time which will worsen the noise phenomena, i. e. reflection, crosstalk, and power system stability during component switching. Several causes to signal integrity issues on the printed circuit boards are analyzed and both proper and improper circuit design techniques are implemented on the Advanced Design System (ADS) software for data collection and analysis. Deliverables at the end this project would be the simulation results to support the study, whereby several simulations are conducted to demonstrate and verify the theoretical study of signal integrity issues. Besides that, the designs will then be fabricated on a two-layer microstrip board and tested on the Digital Communication Analyzer (DCA) to obtain more practical results. A project Gantt chart is attached in the appendix to illustrate the work flow and anticipated progress

Application of Thoracic Ultrasonography for Acute Cor Pulmonale in Acute Respiratory Distress Syndrome Patients

Beneficial therapeutic interventions for acute respiratory distress syndrome (ARDS) include lung protective ventilation; however, ventilator may cause or sometimes worsen acute cor pulmonale (ACP) induced by pulmonary gas exchange disorder and pulmonary vascular dysfunction due to ARDS. The incidence of ACP was 22–50% in mechanically ventilated patients. Currently, point-of-care ultrasound has been widely used in ARDS patients, which becomes much more important in the early detection and management of ARDS and its complications. Application of lung ultrasound combined with echocardiography could monitor respiratory status, hemodynamics, and cardiac function and optimize the ventilation setting in order to protect both lung and right ventricle. This chapter will discuss the pathophysiology of ACP associated with ARDS and the use of point-of-care ultrasound to make protective strategies for lung and right ventricle in detail