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Research Domain:Luminescent Materials; Organic Oxidations; Metal-Nitrogen Multiple Bonds;Metal-Carbon Multiple Bonds. Materials Science and Chemical Catalysis; Country:[CN]
Research Production: Luminescent Materials
Recent studies revealed that platinum(II), gold(I) and copper(I) complexes possess long-lived and emissive electronic excited states which can mediate atom transfer and multi-electron transfer reactions and exciplex formation processes. Of particular interest is the observation of metal-solvent/anion exciplex emissions from d10 metal complexes. With Pt(II) systems, we can perform C-H bond activation and charge separation processes through irradiation with UV-visible light. Current research aims include the design of luminescent metal complexes for selective recognition of biomolecules and multi-electron transfer reactions. We are studying organic triplet emissions that are switched on through metal ion coordination. Applications of phosphorescent metal-organic compounds in organic optoelectronics are under active investigation.

Organic Oxidations
We have studied the oxidation chemistry of ruthenium- and iron-oxo complexes for organic oxidations. With sterically bulky ligands, we have developed ruthenium-oxo catalysts for selective epoxidation of alkenes and stereoselective oxidation of steroids. Our current research is to develop new metal catalysts for organic oxidations by hydrogen peroxide or dioxygen. The design of ruthenium complexes covalently attached to dendritic substituents and water-soluble polymers will be pursued to achieve stereoselective oxidation in aqueous media. We are also studying the oxidation chemistry of high-valent iron complexes with oligopyridine ligands.

Metal-Nitrogen Multiple Bonds
The proposed research involves the elucidation of the electronic factors required for and reactivities of high-valent metal-imido and -nitrido and low valent metal-nitrene complexes. High-valent ruthenium, manganese and iron-imido complexes with different auxiliary ligands are targeted and their reactivities towards organic substrates are studied. New Rh2(II,II) catalysts for catalytic amidation of C-H bonds are designed.

Metal-Carbon Multiple Bonds. Materials Science and Chemical Catalysis
We are studying the synthesis, spectroscopic properties and reactivities of highly reactive metal-carbon multiple bonded complexes. Our objective is to develop new methods for carbenoid transfer reactions that can be used for natural product synthesis and protein modification. We are also probing the electronic structures of M-(C=C-R-)n and M=(C)n=CR2 by spectroscopic methods and ab inito molecular orbital calculations.
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Research Domain:Polymer Synthesis,Liquid Crystalline and Specialty Polymers Country:[CN]
Research Production: Peking University Award for Excellent Teaching (1986 & 2001)
Wang Bao-Yun Award of Chinese Chemical Society (1988)
Ho Ying-Dong award of Ministry of Education (1988)
Science Advancement Award of Ministry of Education (1991)
China Natural Science Award (1997)
Chinese Chemical Society Award for Inovation Paper on Polymer Chemistry (2001)
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Research Domain:Physical Chemistry Country:[CN]
Research Production: Qingshi ZHU is an internationally well-known physical chemist, having obtained distinguished results in the international forefront of science such as molecular local mode vibration and single-molecules chemistry. His research has expedited the fundamental research of chemical physics in China to hold a renowned position internationally. Furthermore, he has made excellent contributions to the national key project such as Isotope Separation by Laser, and to green chemistry research. Meanwhile, as an educator, he has supervised more than 30 excellent Ph.D students. Some of them have gone on to become excellent and talented individuals in this field of scientific research.
Since assuming the presidency of USTC in June of 1998, he has been dedicating to building USTC into a first-class university geared to the 21st century. Highly effective results have been attained on pushing forward the reform and development of teaching, scientific research, management and logistics.
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Research Domain:Electronic materials processing, Thermochemistry and phase diagrams, Chemical vapor deposition and bulk crystal growth, Photovoltaics Country:[CN]
Research Production: Brief Description of Current Research

Our group’s current research efforts are largely devoted to the study of advanced electronic materials processing issues, particularly those related to thin film deposition (the group operates one Molecular Beam Epitaxy (MBE) and six chemical vapor deposition (CVD) systems. In one system we have coupled a Raman spectrometer to a CVD reactor, which can be x-y-z translated to measure gas phase composition and temperature profiles. Raman scattering and LIF, along with reactor modeling, are being used to quantitatively study homogeneous thermal decomposition mechanisms of organometallic precursors. These reaction mechanisms and rate constants are then used to optimize reactor designs and operating conditions. Current studies are focused on the thermal decomposition of column II and III alkyls.

Two of the CVD reactors (commercial metalorganic and hydride vapor phase epitaxy) are devoted to the growth of GaN and related materials. These wide-bandgap materials are of interest for visible and UV light emitting devices as well as high-temperature and high-power applications. Current projects include growth of thick GaN on Si, nucleation and growth of GaN and InN nanorods, and exploring the growth characteristics and properties of InN.

The performance and functionality of integrated circuits (IC) have continuously improved over the last three decades in part through reduction in the physical sizes of features. This reduction has motivated the use of copper metallization schemes to increase conductivity, but brings the need for barrier layers to prevent Cu diffusion into the underlying Si or interlevel dielectric. An NSF Collaborative Research in Chemistry program is supporting work in the development of new precursors to deposit barrier layers (e.g., TaN, WN, LaB6). The industry roadmap requires the barrier film thickness to be ~10% of the minimum feature size, with the next node at 40 nm. To meet conformality requirements at this node, atomic layer deposition (ALD) methods are being studied, including understanding self-limiting adsorption.

The quality of bulk crystals grown from the melt is largely controlled by buoyancy driven flows. Unfortunately, there are very few techniques to visualize flows in opaque, high temperature, and low Pr number semiconductor melts. In a NASA funded program, we are using YSZ solid-state electrochemical cells, placed along the walls of the liquid metal container, to introduce, extract, and monitor dilute concentrations of dissolved atomic oxygen at the sub-ppm level to visualize flow. Coupling the measured values of the concentration of this tracer species as a function of time and location with a detailed model allows the flow dynamics to be estimated. In addition, we are constructing an integrated microsensor system to study short -dimension dynamics in small systems (e.g. drops).

We are participating in collaboration with the Electrical and Materials Sciences departments on research to reduce the costs of manufacturing photovoltaic solar cells based on Cu(In,Ga)Se2 (CIGS) thin film technology. This interdisciplinary program aims to probe fundamental issues such as reaction pathways, point defect chemistry, and phase equilibria, while exploring alternative processes such as MBE, rapid thermal processing, laser annealing, and ALD. Another program is focused on demonstrating tandem solar cells. In this approach, photon-energy in the different wavelength regions of the solar spectrum are more efficiently converted into electricity by using a stack of single-junction solar cells. Our vision is a tandem structure consisting of a CIS (1.04 eV) bottom cell and a CGS (1.68 eV) top cell. In other research, the use of InxGa1-xN solid solutions are being tested as possible PV materials, and organic PV cells are attempting to be integrated with inorganic ones.

The solution to many of the problems in the processing of advanced materials is aided by knowledge of the phase diagram and thermochemistry of these materials. Our group routinely measures component activities in liquid and solid solutions with solid state galvanic cells. This data along with other available data is then critically assessed and solution model parameters estimated to predict multicomponent phase diagrams and compute complex reaction equilibria. We also routinely perform molecular simulations in experimentally difficult systems.
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Research Domain:Modeling of Particle-laden Flows Computational Fluid Dynamics Dem Simulations Country:[CN]
Research Production: Our research work focuses on the development and validation of numerical models for the prediction of fluid-particle flow phenomena. Particle flow processes pervade the pharmaceutical, biomedical, chemical, mining, agricultural, food processing and petroleum industries.

One of our most notable successes is the adoption of our group抯 multiphase flow models by the two key commercial computational fluid dynamics (CFD) software package vendors (Fluent and AEA Technology). We are currently expanding the capability of these models to describe particulate systems that contain highly non-spherical, cohesive, and/or rough particles with a size distribution that evolves with time due to chemical reaction, particle agglomeration, or attrition. In addition, we are developing models which describe both particle clustering, a flow phenomenon characteristic of dense-phase particle transport, as well as the effect of the interstitial fluid on particle-particle and particle-wall interactions. We also employ the Discrete Element Method (DEM) to simulate the details of the motion of individual particles to give insight into both the development of closure relations for the CFD models, as well as phenomena such as particle segregation and mixing in blenders and hoppers.

Our group also has a complementary experimental research program involving detailed, non-intrusive flow measurements using laser Doppler velocimetry and flow visualization. These measurements allow us to explore, in a highly controlled fashion, a range of effects such as the influence of the particle size distribution and the effect of the interstitial fluid on particle velocity fluctuations. Refractive index matching is used for liquid-solid systems.
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Research Domain:Pharmacology Country:[CN]
Research Production: Research Interests

Much of our research centers on the signal transduction pathways that trigger Xenopus oocyte maturation. This is an intrinsically important question--it sits at the heart of understanding fertility and reproduction--with a rich history of spinning off discoveries with broad implications for our understanding of the cell cycle (e.g. the discovery of M-phase promoting factor, MPF).

In addition, the signal transduction networks that trigger Xenopus oocyte maturation--the MAPK cascade and the Cdc2-cyclin B system--are of great importance in many biological contexts. We are studying how these networks function as systems. The oocyte provides in vitro and ex vivo experimental systems of unequaled power for carrying out quantitative biochemical studies, and we complement these experimental studies with computational approaches.
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Research Domain:cell cycle regulation, cell cycle checkpoint, DNA damage, DNA repair, genomic stability, chemical biology, ATR kinase, signal transduction Country:[CN]
Research Production: Research Description:
My lab is focused on understanding the mechanism that the cell uses to maintain genomic stability, with an emphasis on DNA damage checkpoints. Components of these checkpoints effectively monitor the status of the genome, sensing the presence of DNA damage and coordinating a range of possible responses, including DNA repair, apoptosis, arrest of cell cycle progression, and maintenance of replication fork stability. Loss of this checkpoint response is a hallmark of cancer cells and is one of the early steps in the development of cancer.

We are studying the DNA damage response using both cell-free extracts derived from the eggs of the frog Xenopus laevis as well as cultured mammalian cells. We are using these systems and a range of multidisciplinary techniques to understand how the checkpoint is activated following DNA damage and how this pathway is integrated with the processes of DNA replication, cell cycle progression and DNA repair.

Specific areas of current interest are:
• Checkpoint Activation.
• Checkpoint Signaling .
• Chemical Modulation of Checkpoint Pathways .
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Research Domain: Membrane and colloid science, electrokinetic phenomena (especially electrophoresis, electroosmosis and microfluidics), bioengineering Country:[CN]
Research Production: Electrokinetic Phenomena
Movement of particles and fluids by electric fields in conducting or partially conducting liquids. We study complex particles (nonuniformly charged), for example, hetero-aggregates, crystalline particles, polyelectrolytes; and electroosmotic flows driven by electric fields in confined spaces with patterned surfaces, with applications to microfluidics and colloid patterning on demand at pixel level.

Electrophoretic Deposition
Particle interactions on electrodes in dc and ac electric fields. We study two-particle interactions resulting from particle-generated electroosmotic flows near the electrode and electrodynamic flow caused by electrolyte polarization near the electrode.

Bubble Coalescence on Surfaces
Bubbles on heated or cooled surfaces interact over large length scales because of thermocapillary flows about their surfaces. Bubbles come together on hot surfaces and separate on cold surfaces. Our studies focus on the dynamics of two bubbles on surfaces.

Tissue Engineering
Working with collaborators in biology, we are developing synthetic constructs to mimic tissues and study the transport of growth factors and other macromolecules in these constructs. Our main interest is in the combined effects of diffusion, convection and adsorption/desorption on the spatial and temporal distribution of growth factors.
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Research Domain:Understanding embryonic development and oncogenesis at the molecular level, including biochemical events within the Hedgehog and Wnt pathways. Country:[CN]
Research Production: Our laboratory investigates the molecular basis of embryonic development and oncogenesis through a multidisciplinary approach. We recently identified the cellular target of cyclopamine, a teratogen found in corn lilies, providing a long-awaited explanation for a mysterious outbreak of cyclopic sheep in the 1950s. Through genetic and biochemical methods, we have demonstrated that cyclopamine blocks an embryonic signaling cascade called the Hedgehog pathway by binding directly to Smoothened, a transmembrane protein that transduces the Hedgehog signal. Complementary studies in our laboratory have also identified Smoothened as the physiological target of another Hedgehog pathway-modulating small molecule, in this case a synthetic agonist discovered through high-throughput screens. These collective studies have yielded insights into the molecular mechanisms of Smoothened activation and suggest that Smoothened function is regulated by an endogenous small molecule. Furthermore, cyclopamine and other Smoothened inhibitors may constitute highly specific anti-tumor therapies, since aberrant Hedgehog signaling plays a critical role in the initiation and maintenance of numerous cancers. Building upon this foundation, mechanistic studies of Hedgehog signaling events downstream of Smoothened are now underway, employing both chemical and genetic strategies. Our laboratory is also pursuing related studies of Wnt signaling, another pathway intimately involved with embryonic development and the formation of certain tumors.

A second goal of our laboratory is the development of new methods for the study of vertebrate embryogenesis, using zebrafish as a model organism. The optical transparency and rapid development of zebrafish embryos have favored their use in studies of vertebrate patterning, and their susceptibility to chemical- or retrovirus-induced mutagenesis has led to the identification of several thousand mutant strains that will be invaluable tools for embryological research. However, reverse-genetic approaches to the study of zebrafish gene function have significantly lagged behind experimental methods available for other organisms that are less amenable to direct embryological observation. Bridging this gap is a major aim of our laboratory, and we are currently pursuing two independent strategies for the spatial and temporal control of gene expression in zebrafish. Both multidisciplinary approaches will enable the generation of zebrafish embryos with precisely tailored gene expression patterns, providing new opportunities for understanding vertebrate development at the molecular and systems levels.
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Research Domain:Polymer Physics, Interfaces and Assemblies Country:[CN]
Research Production: William M. Keck Sr. Professor of Chemical Engineering and
(by courtesy)Professor of Chemistry and Professor of Materials Science and Engineering

Ph.D., University of Illinois, 1972. Fellow, American Physical Society. C. M. A. Stine Award, American Institute of Chemical Engineers. Principal Investigator, National Science Foundation Materials Research Science and Engineering Center on Polymer Interfaces and Macromolecular Assemblies (CPIMA).
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