South University of Science and Technology of China is a public research university in Shenzhen, People's Republic of China. The establishment of the university has a great meaning to Chinese education. South University of Science and Technology is a national higher education and comprehensive reform experiment, bears exploration of the Chinese educational innovation. Wikipedia.
Zeng H.,University of Hong Kong |
Dai J.,South University of Science and Technology of China |
Yao W.,University of Hong Kong |
Xiao D.,Oak Ridge National Laboratory |
Cui X.,University of Hong Kong
Nature Nanotechnology | Year: 2012
Most electronic devices exploit the electric charge of electrons, but it is also possible to build devices that rely on other properties of electrons. Spintronic devices, for example, make use of the spin of electrons. Valleytronics is a more recent development that relies on the fact that the conduction bands of some materials have two or more minima at equal energies but at different positions in momentum space. To make a valleytronic device it is necessary to control the number of electrons in these valleys, thereby producing a valley polarization. Single-layer MoS 2 is a promising material for valleytronics because both the conduction and valence band edges have two energy-degenerate valleys at the corners of the first Brillouin zone. Here, we demonstrate that optical pumping with circularly polarized light can achieve a valley polarization of 30% in pristine monolayer MoS 2. Our results, and similar results by Mak et al., demonstrate the viability of optical valley control and valley-based electronic and optoelectronic applications in MoS 2 monolayers. © 2012 Macmillan Publishers Limited. All rights reserved.
Hu F.,University of Alabama |
Hao Q.,South University of Science and Technology of China |
Bao K.,University of Alabama
IEEE Communications Surveys and Tutorials | Year: 2014
Software-defined network (SDN) has become one of the most important architectures for the management of largescale complex networks, which may require repolicing or reconfigurations from time to time. SDN achieves easy repolicing by decoupling the control plane from data plane. Thus, the network routers/switches just simply forward packets by following the flow table rules set by the control plane. Currently, OpenFlow is the most popular SDN protocol/standard and has a set of design specifications. Although SDN/OpenFlow is a relatively new area, it has attracted much attention from both academia and industry. In this paper, we will conduct a comprehensive survey of the important topics in SDN/OpenFlow implementation, including the basic concept, applications, language abstraction, controller, virtualization, quality of service, security, and its integration with wireless and optical networks. We will compare the pros and cons of different schemes and discuss the future research trends in this exciting area. This survey can help both industry and academia R&D people to understand the latest progress of SDN/OpenFlow designs. © 2014 IEEE.
Guo X.,South University of Science and Technology of China |
Facchetti A.,Northwestern University |
Facchetti A.,Polyera Corporation |
Marks T.J.,Northwestern University
Chemical Reviews | Year: 2014
A study reviews the applications of organic semiconductors in two of the most active fields of organic optoelectronics: organic thin-film transistors (OTFTs) and organic solar cells (OSCs). Polymer semiconductors having a common structural component, the imide or amide functional group, connected to π-conjugated cores are specifically discussed in the study. Three critical OTFT performance parameters are charge carrier mobility, current modulation ratio, and threshold voltage. The performance parameters can be derived from the OTFT output and transfer characteristics.
He J.,South University of Science and Technology of China |
Kanatzidis M.G.,Northwestern University |
Dravid V.P.,Northwestern University
Materials Today | Year: 2013
One of the intellectual challenges for next generation thermoelectric materials revolves around the synthesis and fabrication of hierarchically organized microstructures that do not appreciably compromise the innate high power factor of the chosen thermoelectric system, but significantly reduce lattice thermal conductivity to enhance the overall figure of merit, ZT. An effective emerging strategy is to introduce nanostructures into bulk thermoelectric materials, which allow for diverse phonon scattering mechanisms to reduce thermal conductivity. In this review, we present key examples to show the intricate but tractable relationship across all relevant length-scales between various microstructural attributes (point, line, interfacial and mesoscale defects; as well as associated elastic and plastic strain) and lattice thermal conductivity in systems based on PbTe matrices. We emphasize the need for an overarching panoscopic approach that enables specific design strategies for the next generation of thermoelectric materials. © 2013 Elsevier Ltd.
Liang Y.,Stanford University |
Liang Y.,South University of Science and Technology of China |
Li Y.,Stanford University |
Wang H.,Stanford University |
Dai H.,Stanford University
Journal of the American Chemical Society | Year: 2013
Electrochemical systems, such as fuel cell and water splitting devices, represent some of the most efficient and environmentally friendly technologies for energy conversion and storage. Electrocatalysts play key roles in the chemical processes but often limit the performance of the entire systems due to insufficient activity, lifetime, or high cost. It has been a long-standing challenge to develop efficient and durable electrocatalysts at low cost. In this Perspective, we present our recent efforts in developing strongly coupled inorganic/nanocarbon hybrid materials to improve the electrocatalytic activities and stability of inorganic metal oxides, hydroxides, sulfides, and metal-nitrogen complexes. The hybrid materials are synthesized by direct nucleation, growth, and anchoring of inorganic nanomaterials on the functional groups of oxidized nanocarbon substrates including graphene and carbon nanotubes. This approach affords strong chemical attachment and electrical coupling between the electrocatalytic nanoparticles and nanocarbon, leading to nonprecious metal-based electrocatalysts with improved activity and durability for the oxygen reduction reaction for fuel cells and chlor-alkali catalysis, oxygen evolution reaction, and hydrogen evolution reaction. X-ray absorption near-edge structure and scanning transmission electron microscopy are employed to characterize the hybrids materials and reveal the coupling effects between inorganic nanomaterials and nanocarbon substrates. Z-contrast imaging and electron energy loss spectroscopy at single atom level are performed to investigate the nature of catalytic sites on ultrathin graphene sheets. Nanocarbon-based hybrid materials may present new opportunities for the development of electrocatalysts meeting the requirements of activity, durability, and cost for large-scale electrochemical applications. © 2013 American Chemical Society.