@article{wu_mosher_lyons_zeng_2010, title={Reducing Ability and Mechanism for Polyvinylpyrrolidone (PVP) in Silver Nanoparticles Synthesis}, volume={10}, ISSN={["1533-4899"]}, DOI={10.1166/jnn.2010.1915}, abstractNote={Recently, it has been found that polyvinylpyrrolidone (PVP), a popular stabilizer in nanoparticles syntheses, possesses reducing ability for Ag+. Previous explanations of the reduction are, however, thought to be plausible. Based on detailed characterizations including UV-Vis, FTIR-ATR and XPS, we uncover the existence of Ag+ -O interaction, and demonstrate that the Ag+ -PVP complex is first formed via the coordination between Ag+ and O in the carbonyl group, which facilitates electron exchange between Ag+ and adjacent N atom on the pyrrolidone ring. The N atoms with lone pair electrons serve as an electron donator, leading reduction of Ag- to form PVP-capped Ag nanoparticles ultimately.}, number={4}, journal={JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY}, author={Wu, Chunwei and Mosher, Brian P. and Lyons, Kevin and Zeng, Taofang}, year={2010}, month={Apr}, pages={2342–2347} } @article{wu_mosher_zeng_2008, title={Powder-based nanoparticles fabrication technique in solution phase}, volume={188}, ISSN={["1873-328X"]}, DOI={10.1016/j.powtec.2008.04.038}, abstractNote={A highly efficient method, using ultrafine aluminum powder as heterogeneous reducing media as well as sacrificial template, has been developed to prepare various metallic or oxide nanoparticles including Au, Ag, Pt, RuO2 and Cu2O with good monodispersity. With the aid of ultrasonication-induced physical effects such as acoustic cavitation and microstreaming, zerovalent metallic atoms or clusters, when generated, are immediately dislodged from the surface of aluminum powder and are driven into bulk solution phase, avoiding the surface deposition and reaction termination. Ultrasonication also plays a critical role in promoting the mass transport through the channels in the amorphous and porous Al2O3 passivation layer around aluminum particles. The method opens a general and potent avenue for preparation of high-quality nanoparticles in large quantity and in a way that is environmentally friendly.}, number={2}, journal={POWDER TECHNOLOGY}, author={Wu, Chunwei and Mosher, Brian P. and Zeng, Taofang}, year={2008}, month={Dec}, pages={166–169} } @article{geng_kiker_ordon_kuznetsov_zeng_roberts_2007, title={Combined numerical and experimental investigation of a hobby-scale pulsejet}, volume={23}, ISSN={["1533-3876"]}, DOI={10.2514/1.18593}, abstractNote={The pulsejet, due to its simplicity, may be an ideal micro propulsion system, but has received very little attention since the mid 1950’s. Here, modern computational and experimental tools are used to investigate the operation of a hobby scale (50 cm overall length) pulsejet. Gas dynamics, acoustics and chemical kinetics are all involved and are studied to gain an understanding of the various physical phenomena affecting pulsejet operation, scaleability and efficiency. A Bailey Machining Service (BMS) hobby pulsejet is instrumented to obtain pressure, temperature, thrust, and frequency. CH * chemiluminescence is utilized to determine combustion time and high speed imaging of the reed valve operation is undertaken to determine the valve duty cycle. Laser Doppler Velocimetry (LDV) has been used to measure the instantaneous exhaust velocity in these unsteady combustion devices. Numerical simulations are performed utilizing CFX to model the 3-D compressible vicious flow in the pulsejet using the integrated Westbrook-Dryer single step combustion model. The turbulent flow and reaction rate are modeled with the ke model and the Eddy Dissipation Model (EDM), respectively. Simulation results provide physical insight into the pulsejet cycle; comparisons with experimental data obtained in this research are carried out. The traditional view of a pulsejet as a 1/4 wave tube operating on the Humphrey cycle is modified with to account for valve operation and finite chemical kinetics.}, number={1}, journal={JOURNAL OF PROPULSION AND POWER}, author={Geng, T. and Kiker, A., Jr. and Ordon, R. and Kuznetsov, A. V. and Zeng, T. F. and Roberts, W. L.}, year={2007}, pages={186–193} } @article{wu_mosher_zeng_2006, title={One-step green route to narrowly dispersed copper nanocrystals}, volume={8}, ISSN={["1572-896X"]}, DOI={10.1007/s11051-005-9065-2}, number={6}, journal={JOURNAL OF NANOPARTICLE RESEARCH}, author={Wu, Chunwei and Mosher, Brian P. and Zeng, Taofang}, year={2006}, month={Dec}, pages={965–969} } @article{mosher_wu_sun_zeng_2006, title={Particle-reinforced water-based organic-inorganic nanocomposite coatings for tailored applications}, volume={352}, ISSN={["1873-4812"]}, DOI={10.1016/j.jnoncrysol.2006.05.026}, abstractNote={We report the synthesis and characterization of three particle-reinforced water-based nanocomposite coatings. The films are sol–gel derived using non-ionic surfactant, with aluminum perchlorate (Al(ClO4)3) as a catalyst and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursor. Through the aid of nanoparticle colloids and a minute amount of catalyst, dense, hard and monolithic materials are obtained. Incorporating metal oxide nanoparticles brings forth unique properties, such as absorbing harmful UV radiation. Silica colloid composites provide greatly enhanced mechanical properties without modifying the unique optical properties of inorganic materials. Water-based synthesis of these coatings is straightforward and produces very few harmful byproducts, making them ideal materials in industry. The materials presented are relatively hard and abrasion resistant with very good adhesion; two of the coatings are UV absorbent. Various colloids can be employed in our methods to tailor properties and resulting materials may serve applications such as optical, protective, catalytic, guest-host, and multifunctional coatings.}, number={30-31}, journal={JOURNAL OF NON-CRYSTALLINE SOLIDS}, author={Mosher, Brian P. and Wu, Chunwei and Sun, Tao and Zeng, Taofang}, year={2006}, month={Sep}, pages={3295–3301} } @article{wu_mosher_zeng_2006, title={Rapid synthesis of gold and platinum nanoparticles using metal displacement reduction with sonomechanical assistance}, volume={18}, ISSN={["1520-5002"]}, DOI={10.1021/cm052400x}, abstractNote={We present a new route for preparation of metallic nanoparticles by sonomechanical-assisted metal displacement reduction. Au and Pt nanoparticles with sizes around 10 and 6 nm, respectively, and narrow size distributions were synthesized via the displacement reduction of precursor salts of HAuCl4·3H20 and H2PtCl6·6H2O by Cu and Fe foils, respectively.}, number={13}, journal={CHEMISTRY OF MATERIALS}, author={Wu, Chunwei and Mosher, Brian P. and Zeng, Taofang}, year={2006}, month={Jun}, pages={2925–2928} } @article{wu_zeng_2007, title={Size-tunable synthesis of metallic nanoparticles in a continuous and steady-flow reactor}, volume={19}, ISSN={["0897-4756"]}, DOI={10.1021/cm062344f}, abstractNote={The TEM image of silver nanoparticles is synthesized by the continuous and steady-flow process.}, number={2}, journal={CHEMISTRY OF MATERIALS}, author={Wu, Chunwei and Zeng, Taofang}, year={2007}, month={Jan}, pages={123–125} } @article{zeng_2006, title={Thermionic-tunneling multilayer nanostructures for power generation}, volume={88}, ISSN={["1077-3118"]}, DOI={10.1063/1.2192973}, abstractNote={A method for power generation based on nanoengineered interface design with partially filled gap is presented. The proposed device allows a substantial temperature difference to exist between heat source and heat sink or two electrodes, thereby maximizing heat source utilization. A unified model and detailed analyses are provided for the solid device operating either as a power generator or as a cooler. Our analyses show that efficiency of about 50% of the corresponding Carnot efficiency can be achieved.}, number={15}, journal={APPLIED PHYSICS LETTERS}, author={Zeng, TF}, year={2006}, month={Apr} } @article{zeng_sun_2005, title={Size effect of nanoparticles in chemical mechanical polishing - A transient model}, volume={18}, ISSN={["1558-2345"]}, DOI={10.1109/TSM.2005.858508}, abstractNote={When a workpiece to be polished is placed on the carrier of a polishing machine, it is pressed down to the polishing pad. Large abrasives make contact between the pad and the workpiece before the smaller ones. The larger abrasives are pressed into the pad and indented into the workpiece. These particles are the active abrasives and participate in material removal. The abrasives with a size less than the gap between the pad and the workpiece move freely in the valleys/voids of the pad and are inactive. As the gap decreases during the polishing process, smaller abrasives trapped between the pad and the workpiece become active in polishing. Thus, the process of chemical-mechanical polishing is dynamic, while all previous modeling is static. This paper establishes a dynamic model for the abrasives. The modeling considers the transient motion of the workpiece/particle/pad in the vertical direction and the change of the roughness of the workpiece. A study of the transient motion shows an increasing number of active particles and a changing polishing rate in the first 2 min. It also demonstrates that the viscoelastic properties of the pad and the workpiece surface roughness are important factors in determining the polishing rate. This paper also shows that when the average particle size is smaller than an optimum size, the polishing rate increases with increasing particle size for the same particle density or same wt% abrasives. Yet, if the average particle size is larger than the optimum size, the polishing rate decreases with increasing particle size.}, number={4}, journal={IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING}, author={Zeng, TF and Sun, T}, year={2005}, month={Nov}, pages={655–663} } @article{zeng_chen_2003, title={Nonequilibrium electron and phonon transport and energy conversion in heterostructures}, volume={34}, ISSN={["0026-2692"]}, DOI={10.1016/S0026-2692(02)00189-1}, abstractNote={We establish a unified model dealing with the transport of electrons and phonons in double heterojunction structures with the coexistence of three nonequilibrium processes: (1) nonequilibrium among electrons, (2) nonequilibrium among phonons, and (3) nonequilibrium between electrons and phonons. Using this model, we investigate the energy conversion efficiency based on concurrent thermoelectric and thermionic effects on electrons and size effects on electrons and phonons. It is found that heterostructures can have an equivalent figure of merit higher than the corresponding bulk materials.}, number={3}, journal={MICROELECTRONICS JOURNAL}, author={Zeng, TF and Chen, G}, year={2003}, month={Mar}, pages={201–206} } @article{zeng_liu_2003, title={Phonon heat conduction in micro- and nano-core-shell structures with cylindrical and spherical geometries}, volume={93}, ISSN={["0021-8979"]}, DOI={10.1063/1.1556566}, abstractNote={This study examines the definition of temperatures at interfaces and within thin films when the phonons are in nonequilibrium, and provides a general solution for the temperature distribution within the micro- and nanocylindrical and spherical shells. By applying the Boltzmann transport equation and the established methods of thermal radiation heat transfer, analytical solutions for the temperature distribution and equivalent thermal conductivity are obtained for micro- and nanocylindrical and spherical shells. The study shows that significant drops in temperature occur at the interfaces of micro- and nanocylindrical and spherical shells. For cylindrical shells, the effective thermal conductivity is determined by both the film thickness and the diameter of the inner cylinder. For spherical shells, the effective conductivity is mainly determined by the size of the inner sphere.}, number={7}, journal={JOURNAL OF APPLIED PHYSICS}, author={Zeng, TF and Liu, W}, year={2003}, month={Apr}, pages={4163–4168} }