Yang Yang

Bio: Yang Yang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Medicine & Computer science. The author has an hindex of 171, co-authored 2644 publications receiving 153049 citations. Previous affiliations of Yang Yang include Zhejiang University & Northwest Normal University.

Regulation of tumor cell migration and invasion by the H19/let-7 axis is antagonized by metformin-induced DNA methylation.

Abstract: The imprinted, developmentally regulated H19 long noncoding RNA has been implicated in the pathogenesis of diverse human cancers, but the underlying mechanisms have remained poorly understood. Here, we report that H19 promotes tumor cell migration and invasion by inhibiting let-7, a potent tumor suppressor microRNA that functions to posttranscriptionally suppress the expression of oncogenes that regulate cell growth and motility. We show that H19 depletion impairs, whereas its overexpression enhances the motility and invasiveness of tumor cells. These phenomena occur, at least in part through affecting let-7-mediated regulation of metastasis-promoting genes, including Hmga2, c-Myc and Igf2bp3. This H19/let-7-dependent regulation is recapitulated in vivo where co-expressions of oncogenes and H19 exist in both primary human ovarian and endometrial cancers. Furthermore, we provide evidence that the anti-diabetic drug metformin inhibits tumor cell migration and invasion, partly by downregulating H19 via DNA methylation. Our results reveal a novel mechanism underpinning H19-mediated regulation in metastasis and may explain why in some cases increased let-7 expression unexpectedly correlates with poor prognosis, given the widely accepted role for let-7 as a tumor suppressor. Targeting this newly identified pathway might offer therapeutic opportunities.

Controlled Rod Nanostructured Assembly of Diphenylalanine and Their Optical Waveguide Properties

Abstract: Diphenylalanine (FF) microrods were obtained by manipulating the fabrication conditions. Fourier transform infrared (FTIR), circular dichroism (CD), fluorescence (FL) spectroscopy, and X-ray diffraction (XRD) measurements revealed the molecular arrangement within the FF microrods, demonstrating similar secondary structure and molecular arrangement within FF microtubes and nanofibers. Accordingly, a possible mechanism was proposed, which may provide important guidance on the design and assembly manipulation of peptides and other biomolecules. Furthermore, characterization of a single FF microrod indicates that the FF microrod can act as an active optical waveguide material, allowing locally excited photoluminescence to propagate along the length of the microrod with coupling out at the microrod tips.

Polymer memory device based on conjugated polymer and gold nanoparticles

Abstract: Electrical bistability is demonstrated in a polymer memory device with an active layer consisting of conjugated poly3-hexylthiophene and gold nanoparticles capped with 1-dodecanethiol sandwiched between two metal electrodes. The device was fabricated through a simple solution processing technique and exhibited a remarkable electrical bistable behavior. Above a threshold voltage the pristine device, which was in a low conductivity state, exhibited an increase in conductivity by more than three orders of magnitude. The device could be returned to the low conductivity state by applying a voltage in the reverse direction. The electronic transition is attributed to an electric-field-induced charge transfer between the two components in the system. The conduction mechanism changed from a charge-injection-controlled current in the low conductivity state to a charge-transport-controlled current in the high conductivity state. In the high conductivity state the conduction was dominated by a field-enhanced thermal excitation of trapped charges at room temperature, while it is dominated by charge tunneling at low temperatures. The device exhibited excellent stability in both the conductivity states and could be cycled between the two states for numerous times. The device exhibits tremendous potential for its application as fast, stable, low-cost, high storage density nonvolatile electronic memory. © 2006 American Institute of Physics. DOI: 10.1063/1.2337252

Unique architecture and concept for high-performance organic transistors

Abstract: We report an organic transistor with a vertically stack structure, which consists of a layer-by-layer active cell (drain/organics/source) on top of a capacitor cell (source/dielectrics/gate); the middle source electrode is shared by the capacitor cell and active cell. Three unique characteristics of this transistor, (a) its very thin and rough middle source electrode; (b) its capacitor cell with high charge-storage capability, allow the active cell to be influenced when the gate is biased; and (c) the large cross-section area and small distance between the source and the drain allow current flowing between the source and drain electrodes. Devices have been fabricated by thermal evaporation with the source-drain current well modulated by the gate potential. We have achieved organic transistors with low working voltage (less than 5V) and high current output (up to 10mA or 4A∕cm2) and an ON/OFF ratio of 4×106. A model is proposed for the device operation mechanism. The demonstrated device with its enhanced operating characteristics may open directions for organic transistors and their applications.

Highly Efficient Red‐Emission Polymer Phosphorescent Light‐Emitting Diodes Based on Two Novel Tris(1‐phenylisoquinolinato‐C2,N)iridium(III) Derivatives

Abstract: Organic light-emitting diodes (OLEDs) have often been considered one of the important candidates for the next generation of flat-panel displays, because of their emissive capability and fast response time. To enhance the efficiency, phosphorescent dyes have become an attractive research subject in OLEDs because of their ability to boost the internal quantum efficiency to 100 %. Although polymer phosphorescent light-emitting diodes (P-PhoLEDs) have been making progress in achieving high efficiencies, polymeric LEDs (P-LEDs) are lagging behind in this category of technology. Unbalanced electron and hole currents are considered to be one of the main obstacles; these are mainly caused by a lack of fine engineering of the multiple layers by the solution process. Interfacial layers such as LiF between a metal cathode and polymer are commonly used to enhance electron injection, and hence to achieve a better balance between the electron and hole currents. However, the electron-injection enhancement caused by these interfacial materials cannot be precisely controlled, so in most cases the electron and hole currents are not perfectly balanced. Intensive work has been devoted to high-efficiency green emitting P-PhoLEDs, in which poly(N-vinylcarbazole) (PVK) is chosen as the host material for its high triplet energy level, and fac tris(2-phenylpyridine) iridium (Ir(ppy)3) or tris(2-4-tolyl phenylpyridine) iridium (Ir(mppy)3) is the dopant. By improving its electrical properties and device energy structure, the highest power efficiency of 67 lm W has been realized based on Ir(mppy)3. [6] However, there are far fewer reports about red-emission P-PhoLEDs for various reasons. In this manuscript, we report on very high efficiency solutionprocessed red P-PhoLEDs. Two novel red iridium-based phosphorescence dyes were used as dopants, and a polyfluorene derivative (PF) was used as the host material in this work. Pure-red emission from dopants was obtained at 4–6 wt % dopant in the host polymer. An electron-injection/hole-blocking layer, Cs2CO3, was inserted between the light-emitting polymer (LEP) layer and the Al cathode through thermal deposition. By modulating the thickness of the Cs2CO3 layer, the electron injection could be precisely controlled to balance the hole injection. Direct trapping of charge by the dopants, which could be procured by changing the polymer thickness, helped to increase the efficiency of the device. By optimizing the parameters of the devices, peak efficiencies of 16.9 cd A and 17.6 lm W at 220 cd m were achieved for red-emission P-PhoLEDs. Even at a high brightness of 1000 cd m, our best device still had a very high efficiency of 16 cd A and 13.4 lm W. To the best of our knowledge, these are the highest reported efficiencies for red-emission P-PhoLEDs. Most importantly, this technique is universal for achieving high-efficiency P-LEDs, and has been successfully applied in other material systems. Red-emissive homoleptic cyclometalated iridium complexes were found to have a high efficiency. A PhoLED with an external quantum efficiency of 10.3 % and a power efficiency of 8.0 lm W at 100 cd m has been realized by adopting tris(1-phenylisoquinolinato-C2,N)iridium(III) (Ir(piq)3) as the emission dopant. Originally, it was hoped that Ir(piq)3 could be directly applied as dopant into the polymer host for red emission. Unfortunately it was found that Ir(piq)3 did not dissolve in many common solvents such as p-xylene, chlorobenzene, and toluene. In order to use the cheap solution process for device fabrication, we used two materials, substituted with a long alkyl chain and fluorine, respectively. These substituents increased the solubility remarkably. Figure 1 shows the chemical structures of both compounds. The highest occupied molecular orbital (HOMO) of these materials was measured by using UV photoelectron spectroscopy (UPS) and the lowest unoccupied molecular orbital (LUMO) was calculated based on the UV-vis absorption spectrum edge and the HOMO. The HOMO/LUMO levels of Ir(C8piq)3 were derived from other alkyl-substituted Ir complexes (Ir(R-piq)3). All these data are outlined in Table 1. As expected, the electron-donating alkyl substituent decreased the HOMO/LUMO levels, and the HOMO/LUMO levels of the ligand, having the highly electron-withdrawing fluorine substituent, were increased compared to those of Ir(piq)3. The relative HOMO/LUMO levels of PF and the dopants facilitate the energy transfer from PF to the dopants. Figure 1 shows the photoluminescence (PL) spectra of the two dopants C O M M U N IC A IO N

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.