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Deng Y.,Laboratory of Advanced Materials | Liu S.-J.,Nanjing University of Posts and Telecommunications | Zhao B.-M.,Nanjing University of Posts and Telecommunications | Wang P.,Laboratory of Advanced Materials | And 4 more authors.
Journal of Luminescence | Year: 2011

One new three-arm star-shaped polymer was synthesized by the core-first way using atom transfer radical polymerization (ATRP) method. This polymer contained charged iridium (Ir) complex as the luminescent core and 2-(carbazol-9-yl) ethyl methacrylate as the arm repeat unit. Its structure was confirmed by elemental analysis, nuclear magnet resonance (NMR) and photoluminescence (PL). The polymer has a relatively low polydispersity index (PDI) of 1.30 with excellent thermal stability. It also possesses significant redox behavior with a HOMO level of -5.21 eV, which will be of benefit to hole-injection. The PL spectrum of the polymer in film state has a stable peak at 565 nm, however, its PL in dichloromethane solution varied with its concentration. It demonstrated effective energy transfer from the arm unit to the core in the hostguest system. This indicated that when the length of the arm is properly designed, highly luminescent materials can be achieved with emission at 565 nm. © 2011 Elsevier B.V.

Sun X.,Sun Yat Sen University | Sun X.,Fudan University | Kong B.,Laboratory of Advanced Materials | Kong B.,Monash University | And 11 more authors.
Journal of Materials Chemistry B | Year: 2015

Mesoporous silica nanoparticles (MSNs) that can stably load therapeutic drugs and release them in response to a specific trigger are of great interest in disease diagnosis and treatment. However, the controlled-release of gaseous drug molecules such as hydrogen sulfide (H2S) from a long-range and stable MSN-based system still presents a great challenge. Herein, a MSN-based glutathione (GSH)-triggered controlled-release H2S system has been fabricated with high entrapment efficiency (99.0 ± 0.3%) and loading content (44.2 ± 0.1%) of diallyl trisulfide (DATS). After the addition of GSH (2 mM), DATS-MSN (100 μg mL-1) steadily releases moderate amounts of H2S (peaking at the 4th hour, ∼60 μM) in phosphate buffer solution (PBS). The release of H2S in plasma is similar to a physiological process (peaking at the 4th hour) and the DATS-MSN remains in the plasma of a rat's system over 9 hours without significantly affecting the blood pressure, heart rate and cardiac function. Moderate quantities of nanoparticles can be taken up by cardiomyocytes in vitro, while in vivo study shows that nanoparticles mainly accumulate in the liver and spleen, affecting the H2S level in these organs. Furthermore, DATS-MSN shows excellent biocompatibility, as well as superior cytoprotection and an isolated heart protection effect of H2S under ischemic/reperfusion injury. This study provides a new insight into controlled-release applications of MSN-based H2S releasing systems both in vitro and in vivo. © 2015 The Royal Society of Chemistry.

News Article | December 29, 2015
Site: www.nanotech-now.com

Home > Press > A clue to generate electric current without energy consumption at room temperature Abstract: A group of researchers in Japan and China identified the requirements for the development of new types of extremely low power consumption electric devices by studying Cr-doped (Sb, Bi)2Te3 thin films. This study has been reported in Nature Communications. At extremely low temperatures, an electric current flows around the edge of the film without energy loss, and under no external magnetic field. This attractive phenomenon is due to the material's ferromagnetic properties; however, so far, it has been unclear how the material gains this property. For the first time, researchers have revealed the mechanism by which this occurs. "Hopefully, this achievement will lead to the creation of novel materials that operate at room temperature in the future," said Akio Kimura, a professor at Hiroshima University and a member of the research group. Their achievement can be traced back to the discovery of the quantum Hall effect in the 1980's, where an electric current flows along an edge (or interface) without energy loss. However, this requires both a large external magnetic field and an extremely low temperature. This is why practical applications have not been possible. Researchers believed that this problem could be overcome with new materials called topological insulators that have ferromagnetic properties such as those found in Cr-doped (Sb, Bi)2Te3. A topological insulator, predicted in 2005 and first observed in 2007, is neither a metal nor an insulator, and has exotic properties. For example, an electric current is generated only at the surface or the edge of the material, while no electric current is generated inside it. It looks as if only the surface or the edge of the material has metallic properties, while on the inside it is an insulator. At extremely low temperatures, a thin film made of Cr-doped (Sb, Bi)2Te3 shows a peculiar phenomenon. As the film itself is ferromagnetic, an electric current is spontaneously generated without an external magnetic field and electric current flows only around the edge of the film without energy loss. However, it was previously unknown as to why Cr-doped (Sb, Bi)2Te3 had such ferromagnetic properties that allowed it to generate electric current. "That's why we selected the material as the object of our study," said Professor Kimura. Because Cr is a magnetic element, a Cr atom is equivalent to an atomic-sized magnet. The N-S orientations of such atomic-sized magnets tend to be aligned in parallel by the interactions between the Cr atoms. When the N-S orientations of Cr atoms in Cr-doped (Sb, Bi)2Te3 are aligned in parallel, the material exhibits ferromagnetism. However, the interatomic distances between the Cr atoms in the material are, in fact, too long to interact sufficiently to make the material ferromagnetic. The group found that the non-magnetic element atoms, such as the Sb and Te atoms, mediate the magnetic interactions between Cr atoms and serve as the glue to fix the N-S orientations of Cr atoms that face one direction. In addition, the group expects that its finding will provide a way to increase the critical temperature for relevant device applications. The experiments for this research were mainly conducted at SPring-8. "We would not have achieved perfect results without the facilities and the staff there. They devoted themselves to detecting the extremely subtle magnetism that the atoms of non-magnetic elements exhibit with extremely high precision. I greatly appreciate their efforts," Kimura said. Authors and their affiliations: Mao Ye1,2, Wei Li1,2, Siyuan Zhu3, Yukiharu Takeda4, Yuji Saitoh4, Jiajia Wang5, Hong Pan6, Munisa Nurmamat3, Kazuki Sumida3, Fuhao Ji6, Zhen Liu6, Haifeng Yang1, Zhengtai Liu1, Dawei Shen1,2, Akio Kimura3, Shan Qiao1,2,5, and Xiaoming Xie1,2,5 1 State Key Laboratoryof Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences 2 CAS-Shanghai Science Research Center 3 Graduate School of Science, Hiroshima University 4 Condensed Matter Science Division, Quantum Beam Science Center, Japan Atomic Energy Agency 5 School of physical science and technology, ShanghaiTech University 6 Department of Physics, State Key Laboratory of Surface Physics, and Laboratory of Advanced Materials, Fudan University For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Kong B.,Laboratory of Advanced Materials | Kong B.,Monash University | Tang J.,Laboratory of Advanced Materials | Wu Z.,Monash University | And 7 more authors.
NPG Asia Materials | Year: 2014

In this study, an unconventional antenna-like heterostructure comprised of arrays of nanoporous Prussian blue (PB) nanocube heads/TiO2 nanowire (NW) arms (PB-TiO2) is developed for efficient three-dimensional interfacial sensing of small molecules and cellular activities. Inspired by insect tentacles, which are comprised of both target recognition and signal transduction units, one-dimensional TiO2 NW arrays are grown, followed by selective growth of nanoporous PB nanocubes on the tips of the NW arrays. Due to their high selectivity and bioaffinity toward cells, long biostability under a cell culture adhesion condition (up to 108 h) is obtained, and with its inherent bio-mimetic enzymatic activity, the obtained nanoporous PB nanocubes (head segment) serve as robust substrates for site-selective cell adhesion and culture, which allows for sensitive detection of H 2O2. Simultaneously, the single-crystalline TiO 2 NWs (arm segment) provide efficient charge transport for electrode substrates. Compared with PB-functionalized planar electrochemical interfaces, the PB-TiO2 antenna NW biointerfaces exhibit a substantial enhancement in electrocatalytic activity and sensitivity for H2O 2, which includes a low detection limit (~20 nM), broad detection range (10-8 to 10-5 M), short response time (~5 s) and long-term biocatalytic activity (up to 6 months). The direct cultivation of HeLa cells is demonstrated on the PB-TiO2 antenna NW arrays, which are capable of sensitive electrochemical recording of cellular activity in real time, where the results suggest the uniqueness of the biomimic PB-TiO 2 antenna NWs for efficient cellular interfacing and molecular recognition. © 2014 Nature Publishing Group All rights reserved.

Chen Z.-X.,Fudan University | Ma H.,Laboratory of Advanced Materials | Chen M.-H.,Fudan University | Zhou X.-F.,Fudan University | And 5 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We present design techniques for special optical lattices that allow quantum simulation of spin frustration in two-dimensional systems. By carefully overlaying optical lattices with different periods and orientations we are able to adjust the ratio between the nearest-neighbor and next-nearest-neighbor interaction strengths in a square spin lattice and realize frustration effects. We show that only laser beams of a single frequency are required and the parameter space reachable in our design is broad enough to study the important phases in the J 1-J 2 frustrated Heisenberg model and checkerboard antiferromagnet model. By using the polarization spectroscopy for detection, distinct quantum phases and quantum phase transition points can be characterized straightforwardly. Our design thus offers a suitable setup for simulation of frustrated spin systems. © 2012 American Physical Society.

Xu S.,Laboratory of Advanced Materials | Li D.,Laboratory of Advanced Materials | Wu P.,Laboratory of Advanced Materials
Advanced Functional Materials | Year: 2015

In this work, uniform molybdenum disulfide (MoS2)/tungsten disulfide (WS2) quantum dots are synthesized by the combination of sonication and solvothermal treatment of bulk MoS2 /WS2 at a mild temperature. The resulting products possess monolayer thickness with an average size about 3 nm. The highly exfoliated and defect-rich structure renders these quantum dots plentiful active sites for the catalysis of hydrogen evolution reaction (HER). The MoS2 quantum dots exhibit a small HER overpotential of ≈120 mV and longterm durability. Moreover, the strong fl uorescence, good cell permeability, and low cytotoxicity make them promising and biocompatible probes for in vitro imaging. In addition, this work may provide an alternative facile approach to synthesize the quantum dots of transition metal dichalcogenides or other layered materials on a large scale. © 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

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