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2001

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Articles 1081 - 1110 of 3030

Full-Text Articles in Physical Sciences and Mathematics

Mechanism And Kinetics Of The Reduction Of Nitric Oxide By Granular Activated Carbon Induced By Pdo/Ai2o3 In The Presence Of O2, Tian Sang May 2001

Mechanism And Kinetics Of The Reduction Of Nitric Oxide By Granular Activated Carbon Induced By Pdo/Ai2o3 In The Presence Of O2, Tian Sang

Theses

NOx and particulate matter are the main environmental hazards found in Diesel exhaust. In order to explore a novel method to remove NOx as well as particulate matter, we examined the catalytic reduction of NOx with solid carbonaceous materials as a surrogate for soot in the presence of oxygen. Pd loaded on Al2O3 has been found to be an active catalyst that resists S and H2O poisoning. A catalyst containing of 2.5% PdO on Al203 exhibits as high as 90% conversion of NO to N2 at space velocities …

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A Comparison Of Risks From New Jersey Chemical Facilities And The Benefits Of Risk Communication, Heather R. Dobbs May 2001

A Comparison Of Risks From New Jersey Chemical Facilities And The Benefits Of Risk Communication, Heather R. Dobbs

Theses

The purpose of this study is to determine if the amount of toxic chemicals a facility stores on-site is a valid indicator for determining a facility's risk potential and need to communicate risk information to the public. This study analyzes New Jersey chemical facilities regulated under the CAA's Risk Management Plan (section 112(r)) and their toxic chemical releases and other risk factors to determine if there is a relationship between the amount of toxic chemicals stored on-site and the potential risk from a toxic release. The analysis of data suggests that no relationship exists; therefore, one could assume that all …

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Factors And State Electric Utility Deregulation Policy Influences On Green Power Marketers, Richard Orlusky May 2001

Factors And State Electric Utility Deregulation Policy Influences On Green Power Marketers, Richard Orlusky

Theses

The electric power industry has been restructuring over the last several years to allow market competition in purchasing electric power. Power generation that was traditionally provided by the local electric utility has been deregulated in order to introduce customer choice. The renewable energy sector of the power industry will have to compete with conventional fossil fuel power generators in this market. This research focused on factors and state deregulation policies that are of importance to Green Power Marketers in a retail power market. Green Power Marketers providing service in California, Pennsylvania and New Jersey retail power markets were surveyed to …

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Benthic Communities In Spartina Alterniflora And Phragmites Australis Dominated Salt Marshes, Catherine E. Yuhas May 2001

Benthic Communities In Spartina Alterniflora And Phragmites Australis Dominated Salt Marshes, Catherine E. Yuhas

Theses

The benthic communities were investigated in Phragmites australis and Spartina altemiflora salt marshes, conducted in natural and mitigated salt marshes located in a highly urbanized area, the Hackensack Meadowlands, New Jersey. Benthic samples were taken with a 5-centimeter core at two habitats, the creek bank and the edge of the vegetation in the low marsh zone. Salinity levels and textural and structural sediment characteristics were also collected at each site. A recolonization experiment that utilized sediment from an undisturbed and uncontaminated salt marsh was conducted to determine if substrate is important in benthic colonization. The results suggest that there were …

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Schedule (2001), Association Of Christians In The Mathematical Sciences May 2001

Schedule (2001), Association Of Christians In The Mathematical Sciences

ACMS Conference Proceedings 2001

Thirteenth ACMS Conference on Mathematics from a Christian Perspective

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Table Of Contents (2001), Association Of Christians In The Mathematical Sciences May 2001

Table Of Contents (2001), Association Of Christians In The Mathematical Sciences

ACMS Conference Proceedings 2001

Thirteenth ACMS Conference on Mathematics from a Christian Perspective

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Improving A Brokering System For Linking Distributed Simulations, Thomas B. Stephens May 2001

Improving A Brokering System For Linking Distributed Simulations, Thomas B. Stephens

Dartmouth College Undergraduate Theses

The Agent Based Environment for Linking Simulations (ABELS) is a software framework designed to provide disparate simulations with dynamically updated data sources. It allows simulations and other agents to join a "cloud" of interacting producers and consumers of data. Once they have joined the cloud, they can publish services to other members and use methods published by others. This paper presents the initial design of a set of matchmaking components for the ABELS framework. These components dictate how services describe their abilities and requirements to ABELS. Furthermore, they help ABELS successfully match data producing services to the requests of data …

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Density Of Prairie Skinks (Eumeces Septentrionalis) In Old-Field Habitats, William C. Pitt May 2001

Density Of Prairie Skinks (Eumeces Septentrionalis) In Old-Field Habitats, William C. Pitt

United States Department of Agriculture Wildlife Services: Staff Publications

From 1996–1998 I estimated the density of prairie skinks (Eumeces septentrionalis) in old fields and evaluated the influence of habitat characteristics on density. I estimated prairie skink density from a trapping grid using a mark-recapture method in seven old fields. For each field I estimated arthropod density, percent plant cover and recorded field age and if the field had been burned in the last 5 y. Arthropod density was highly variable among years and fields. Percent plant cover did not explain this variation, as it varied little among fields and years. Prairie skink density ranged from 58–206 adults …

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The Effect Of Preparation Condition On The Photoelectrochemical Performance Of Both The Pani Film And Tio_2-Pani Composite Film On Au, Huai-Guo Huang, Hong-Ping Zhang, Zhi-Xin Zheng, Yan-Yan Xi, Ling-Ling Wu, Zhong-Hua Lin May 2001

The Effect Of Preparation Condition On The Photoelectrochemical Performance Of Both The Pani Film And Tio_2-Pani Composite Film On Au, Huai-Guo Huang, Hong-Ping Zhang, Zhi-Xin Zheng, Yan-Yan Xi, Ling-Ling Wu, Zhong-Hua Lin

Journal of Electrochemistry

Both the PANI(polyaniline) film and TiO 2_PANI composite film on the PATP(p_aminothiophenol)/Au substrate were obtained under different preparation condition by electrochemical methods, and their photoelectrochemical performances were also studied.The results showed that the photoelectrochemical performances of the films depend deeply on the comditions of preparation.The self_assembling of PATP favors the adhesion of PANI.The partially_oxidized PANI has a greater photoelectrochemical response than that of the reduced PANI and oxidized PANI.There is an optimum of film thickness for the photoelectrochemical performance of PANI film.Heat treating is in favor of the photoelectrochemical performance of TiO 2,but decreases the photocurrent response of PANI film.There …

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Electrochemical Studies On The Intermetallic Interaction In Binuclear Ruthenium(Ⅱ) Complexes, Hong Li, Hui Chao, Liang-Nian Ji, Xiong Jiang May 2001

Electrochemical Studies On The Intermetallic Interaction In Binuclear Ruthenium(Ⅱ) Complexes, Hong Li, Hui Chao, Liang-Nian Ji, Xiong Jiang

Journal of Electrochemistry

The electrochemical characteristics and intermetallic interaction of symmetrical binuclear ruthenium(Ⅱ) complexes [Ru2:(bpy) 2Ru(DIPB)Ru(bpy) 2(ClO 4) 4 and Ru2_2H:(bpy) 2Ru(DIPB-2H)Ru(bpy) 2(ClO 4) 2 ]containing dinuclear ligand 2,2_bipyridine(bpy) and bridging ligand 1,4_di[2_imidazo[4,5_f][1,10] phenanthroine]benzene(DIPB) or 1,4_di[2_dehydrogen_imidazo[4,5_f][1,10] phenanthroine]benzene(DIPB_2H) on a platinum electrode have been investigated using cyclic voltammetry,cyclic ac voltammetry and differential capacitance techniques,etc.In acetonitrile solutions with a concentration of 0.1 mol/L TBAP,the central ruthenium ions in Ru2 and Ru2_2H complexes have shown a single 2e reversible oxidation_reduction wave on the cyclic voltammograms with basically the same formal potentials of Ru2_2H and Ru2 and a slightly larger apparent diffusion coefficient of the Ru2_2H complex …

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Electrochemistry Characteristic Of Carbon Steel Under Biofilm And Sulfide Film, Ze-Hua Dong, Xing-Peng Guo, Jia-Shen Zheng, Li-Ming Xu May 2001

Electrochemistry Characteristic Of Carbon Steel Under Biofilm And Sulfide Film, Ze-Hua Dong, Xing-Peng Guo, Jia-Shen Zheng, Li-Ming Xu

Journal of Electrochemistry

Wire Beam Electrode (WBE) made of Q235 carbon steel was applied to study the heterogeneous corrosion beneath biofilm formed by Sulfate Reducing Bacteria (SRB) in culture and sulfide film in solution with 1% NaCl and 300 mg/L S 2- . The potential,galvanic density mapping,as well as polarization curve and Electrochemical Impedance Spectrum (EIS) were measured to predict the localized corrosion under biofilm and sulfide film.As a result,the mapping showed the potential fluctuation on the WBE surface decreased over time due to the conductivity of the biofilm and sulfide film.Therefore,the potential mapping could not be a criterion of localized corrosion under …

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Comparison In Surface Enhanced Raman Scattering On Salicylideneamine Between Silver And Gold Colloid And Silver Mirror Substrate, Zhao Bing, Yukihiro Ozaki May 2001

Comparison In Surface Enhanced Raman Scattering On Salicylideneamine Between Silver And Gold Colloid And Silver Mirror Substrate, Zhao Bing, Yukihiro Ozaki

Journal of Electrochemistry

In recent years, the study of photochromic and thermochromic materials has grown because of their possible applications in the optical processing of information, in addition to the scientific interest. Salicylidineaniles is one of the prospective choices owing to their photochromism caused by intramolecular hydrogen transfer [1～3] (Fig.1). It is generally agreed that, in the salicylideneamine system, photoexcitation is followed by a rapid barrierless proton transfer and subsequent rearrangement to form a colored photoproduct [4] . The photochemistry of the system in fluid solution is different from that of the solid, even in fluid solution, the photo? and thermo?chromic behavior is …

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Performance Of Proton Exchange Membrane Fuel Cell With Co/H_2 Fuel, Hong-Mei Yu, Zhong-Jun Hou, Bao-Lian Yi, Ke-Wan Bi, Jing-Xin Zhang, Zhi-Yin Lin, Ming Han May 2001

Performance Of Proton Exchange Membrane Fuel Cell With Co/H_2 Fuel, Hong-Mei Yu, Zhong-Jun Hou, Bao-Lian Yi, Ke-Wan Bi, Jing-Xin Zhang, Zhi-Yin Lin, Ming Han

Journal of Electrochemistry

Fuel of proton exchange membrane fuel cell(PEMFC) mostly comes from reformate contains CO which will poison the fuel cell electrocatalyst.The effect of CO on the performance of PEMFC was studied in this paper.The results of the experiment show that when CO is fed in PEMFC,the cell voltage will be decreased violently,then it will become steady with some vibration.The poison will become more serious with higher CO content and weaker at higher temperature.The adsorption of CO on the electrocatalyst is reversible. The PtRu electrocatalyst is more suitable for the electrocatalysis of CO/H 2 than Pt electrocatalyst.

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Atmospheric Corrosion Of Steels In China, Cai-Feng Liang May 2001

Atmospheric Corrosion Of Steels In China, Cai-Feng Liang

Journal of Electrochemistry

Data of eight year atmospheric exposures of 17 steels at 7 sites in China were analyzed.The result showed that the most detrimental pollution is sulfur dioxide and chloride ion for corrosion of carbon steels and low alloy weathering steels.This is in accordance with the common knowledge.The effect of sulfur dioxide is serious in the first few years and becomes weak obviously in the later years.The environment factor of humid hot is much more important in long run than the ordinarily acknowledged humidity,pollution for non weathering steels,although it is not obvious in the beginning.If pollution were existed,a severe corrosion may resulted.As …

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Galvanic Corrosion Of Tin-W Electro-Couple During Tungsten Chemical Mechanical Polishing, Xuan Cheng, Chang-Jian Lin May 2001

Galvanic Corrosion Of Tin-W Electro-Couple During Tungsten Chemical Mechanical Polishing, Xuan Cheng, Chang-Jian Lin

Journal of Electrochemistry

Chemical_mechanical polishing (CMP) is a process whereby mechanical and chemical forces are combined to remove material from a wafer and polish it to a flat surface. Tungsten CMP is an important process to gain the global planarity of silicon wafers with tungsten (W) plugs. Tungsten is actually deposited on a thin adhesive layer of titanium nitride (TiN) on silicon. When close to the final stage of polishing, TiN and W will be simultaneously exposed to the polishing chemistry, forming a galvanic couple. The corrosion of TiN and W couple will result in different polish rate. This work studied the potential …

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Preparation Of Ti-Based Nanocrystalline Tio_2 Film Electrode With High Activity, Dao-Bao Chu, Guang-Xia Shen, Xing-Fu Zhou, Chang-Jian Lin, Hua-Shui Lin May 2001

Preparation Of Ti-Based Nanocrystalline Tio_2 Film Electrode With High Activity, Dao-Bao Chu, Guang-Xia Shen, Xing-Fu Zhou, Chang-Jian Lin, Hua-Shui Lin

Journal of Electrochemistry

The potentiostatic electrosynthesis of Ti(EtO) 4 was studied by anodic dissolution of metal titanium(TA1) in solution of 0.005 mol·L -1 (EtO) 4NBr in the ethanol (AR) in the presence negligible CH 3COCH 2COCH 3.The Ti_based nanocrystalline TiO 2 Film electrode (Ti/nano_TiO 2) was prepared by sol_gel method.By TEM,SEM and XRD,it has been shown that the anatase particle of TiO 2 was 10～35 nm in diameter and the film was 0.5 μm in thickness.The nanocrystalline film was composed of a three_diminsional network of interconnected particles.Reodx behavior and electrocatalytic activities of the Ti/nano_TiO 2 electrode were investigated by cyclic voltammetry (CV) from …

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Properties Of Metallized Poly-O-Toluidide Membrane Modified Electrode, Li-Zong Dai, Yi-Ting Xu, Hui-Huang Wu May 2001

Properties Of Metallized Poly-O-Toluidide Membrane Modified Electrode, Li-Zong Dai, Yi-Ting Xu, Hui-Huang Wu

Journal of Electrochemistry

The platinum particles were electrodeposited on poly(o_toluidide),POT,modified electrode,and the surface configuration and crystal orientation of Pt particles were investigated by SEM and XRD.At the same time the oxidation of isopropanol on platinized POT modified electrode was studied.The results indicate that Pt particles deposite towards preferred_orientation;moreover the increase in polymer electroactivity due to proton doping affects the dimension and graininess of deposited Pt particles.At the metallized polymer electrode the oxidation of isopropanol can occur in POT electroactive potential region,however at the more positive than 0.70 V (SCE) potential where POT loses redox activity the electro_oxidation mainly occurrs on Pt particles.It follows …

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Preparation And Properties Of Separator For Lithium-Ion Battery, Xu-Mei Ren, Feng Wu, Chuan Wu, Han-Jun Li, Xue-Jie Huang May 2001

Preparation And Properties Of Separator For Lithium-Ion Battery, Xu-Mei Ren, Feng Wu, Chuan Wu, Han-Jun Li, Xue-Jie Huang

Journal of Electrochemistry

Lithium_ion batteries are well adapted to the new multimedia applications. PP/PE based microporous film is commonly used as separator in commercial lithium ion batteries. Here we report a microporous film which is superior to the commercial available separator. The microporous PVDF polymer separators were prepared by the phase inversion process. The pore size of the separator is  7 μm, and it's porosity is 75%. The membrane in LiPF 6 EC/DEC showed high ionic conductivity (above 10 -3 S/cm at room temperature), and good mechanical properties (10 3 kg/cm 2). The half_cells consisted of Li/PVDF separator/MCMB showed excellent cycling characteristics …

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The Effect Of Calcium On The Properties Of Molybdenum Nitride Electrode, Yun-Gui Zhu, Xue-Liang Li, Dao-Rong Lu, Jian-Bo He, Ji-Huai Xia May 2001

The Effect Of Calcium On The Properties Of Molybdenum Nitride Electrode, Yun-Gui Zhu, Xue-Liang Li, Dao-Rong Lu, Jian-Bo He, Ji-Huai Xia

Journal of Electrochemistry

The effect of calcium on the properties of molybdenum nitride film electrode was studied by using XRD, SEM and cyclic voltammetry. The results show that the specific electric capacity and the voltage operating range of electrode vary with the concentration of additive in the dipping solution. At the optimum concentration of additive in the dipping solution, the specific electric capacity of the electrode is 2.1 times as large as that of the electrode prepared in the dipping solution without additive, and the voltage operating range of electrode is increased by 0.11 V. The active mechanism of calcium on the properties …

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Some Aspects Of Banks And Financial Markets In Emerging Economics., Gurbachan Singh Dr. May 2001

Some Aspects Of Banks And Financial Markets In Emerging Economics., Gurbachan Singh Dr.

Doctoral Theses

Liquidity and Bank RunsThe policy of deposit insurance in the banking sector has succeeded in pre- venting bank runs but it has encouraged moral haxard (Kane, 1985 and 1989). This has increased the cost of capital. So the government and/or the central bank need to regulate (Flannery, 1982). In chapter 2, we ask the question - Is there an alternative to deposit insurance? What is the role of equity capital in this context? Is full insurance optimal?The seminal paper on bank runs by Diamond and Dybvig (1983) argues that a lack of deposit insurance leads to muitiple Nash equilibria, including …

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Study On Corrosion Resistance Of Electroless Nickel Composite Coatings, Tsong-Jen Yang, Meng-Feng Jou May 2001

Study On Corrosion Resistance Of Electroless Nickel Composite Coatings, Tsong-Jen Yang, Meng-Feng Jou

Journal of Electrochemistry

The eletroless nickel composite coating was prepared by uniform dispersion of diamond (or PTFE) particles throughout electroless nickel deposition. Corrosion resistance of composite coating in 3.5% NaCl aqueous solution was investigated by electrochemical analysis, dipping test and salt spray test. The results showed that the corrosion resistance of composite coating was inferior to that of electroless nickel coating if small amount of particles was added to the composite coating. Microsturctural analysis by SEM,AES,XRD,and EPMA indicated that the distribution of phosphorus is not homogeneous in the composite coating. The phosphorus_rich region acts as microcathode, however, the phosphorus_lean region acts as microanode.The …

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Study Of The Oxidation Dynamics Of Ti-Zro_2 Metal-Ceramics, Wen-Chao Li, Li-Dong Teng May 2001

Study Of The Oxidation Dynamics Of Ti-Zro_2 Metal-Ceramics, Wen-Chao Li, Li-Dong Teng

Journal of Electrochemistry

The oxidation dynamics of hot pressed Ti ZrO 2 metal_ceramics with the composition of 50 vol.% Ti and 50 vol.% ZrO 2 has been studied. Thermodynamic analysis shows that Ti could react with O 2 but not with N 2 in the oxidizing process of Ti ZrO 2 composites at 0.1 MPa air. The oxidation dynamic behavior of Ti ZrO 2 composites is analogous to that of pure Ti. The activation energy for the oxygen diffusion in Ti ZrO 2 composites is higher than that in Ti solutions, for the presence of ZrO 2 restrains the oxygen diffusion in Ti …

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Electrochemical Behavior Of Tinicu Shape Memry Alloy In Simulated Body Fluid, Cheng-Hao Liang, Hong-Yan Sui May 2001

Electrochemical Behavior Of Tinicu Shape Memry Alloy In Simulated Body Fluid, Cheng-Hao Liang, Hong-Yan Sui

Journal of Electrochemistry

The study of TiNiCu shape memory alloys(SMA) in Hank's simulated body fluid was carried out.The results showed that narrow passive range was found in acid environment and active anodic dissolution was discovered at 100～150 mV vs SCE on anodic polarization cure of TiNiCu SMA.Temperature had little effect on anodic polarization.With the decrease of pH and the increase of Cl - concentration,pitting corrosion potential ( E b) shifted negatively.The electrochemical capability of TiNiCu SMA was inferior to that of TiNi SMA.Observations by means of XRD and SEM indicate that TiNiCu SMA is not in single crystal structure,which caused irregular electrochemical behavior …

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The Dependence Of Relative Enhancement Of Sers Bands On Temperature, Ling Huang, Jian Shen, Tsing Yu, Qing-Jin Meng May 2001

The Dependence Of Relative Enhancement Of Sers Bands On Temperature, Ling Huang, Jian Shen, Tsing Yu, Qing-Jin Meng

Journal of Electrochemistry

The adsorption and binding behavior of 2,5_dimercapto_1,3,4_thiadizole(DMTD) on silver surface was studied by near_infrared Fourier Transfer surface enhanced Raman scattering(NIR FT-SERS) technique. It was found that the relative intensities of the SERS bands change regularly with the increasing of temperature, which suggests the transformation of the tautomers or the re_orientation of DMTD molecules in the surface layer.

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Corrosion Behavior Of Titanium In Fgd System, C Lin J, L Chang T, T Dung C, L Lee S, D Chyou S, S D Guo May 2001

Corrosion Behavior Of Titanium In Fgd System, C Lin J, L Chang T, T Dung C, L Lee S, D Chyou S, S D Guo

Journal of Electrochemistry

In situ corrosion test of titanium in flue gas desulfurization(FGD)system has been studied.Specimens of commercial Ti alloy have been put in four different locations(i.e,cooler,prescruber,absorber and heater) of the FGD system for 271 days.The corrosion rate is very low(i.e.

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New Progress In Studies Of Lithium Nickel Oxide As Positive Electrode Materials Of Lithium Ion Batteris, Han-San Liu, Yong Yang, Zhong-Ru Zhang, Zu-Geng Lin May 2001

New Progress In Studies Of Lithium Nickel Oxide As Positive Electrode Materials Of Lithium Ion Batteris, Han-San Liu, Yong Yang, Zhong-Ru Zhang, Zu-Geng Lin

Journal of Electrochemistry

Lithium nickel oxide as the positive electrode of lithium ion batteries has aroused more and more interests.This paper reviews the recent reserches on synthesis and element_substitution of LiNiO 2 cathode material,and summarizes the intrinsical relationship between properties and sturcture of the material.The developments of new synthesis methods and mutil_substitution of the material are expecting to be studied in the future research.

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Performance Of A Direct Methanol Fuel Cell, Zhao-Bin Wei, Jian-Guo Liu, Ya-Guang Jiao, Wei-Jiang Zhou, Wen-Zhen Li, Li-Kang Chen, Qin Xin, Bao-Lian Yi May 2001

Performance Of A Direct Methanol Fuel Cell, Zhao-Bin Wei, Jian-Guo Liu, Ya-Guang Jiao, Wei-Jiang Zhou, Wen-Zhen Li, Li-Kang Chen, Qin Xin, Bao-Lian Yi

Journal of Electrochemistry

A direct methanol fuel cell with 9cm 2 active area consists of Pt_Ru/C anode,Pt/C cathode and Nafion 115 membrane.The effect of operating conditions:methanol solution concentration,oxygen pressure and cell temperature on the cell performances was investigated.The results show that performance of single cell was enhanced by increasing oxygen pressure and cell temperature,and a maximum power density 75 mW/cm 2 was obtained in the range of 250_300 mA/cm 2 current density,0.2 MPa oxygen pressure,1.0 mol/L methanol concentration and 75 ℃ cell temperature.When cell operating at room temperature,a relatively low,but a stable performance of cell was also observed.

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Phonon-Pumped Terahertz Gain In N-Type Gaas/Algaas Superlattices, Greg Sun, Richard A. Soref May 2001

Phonon-Pumped Terahertz Gain In N-Type Gaas/Algaas Superlattices, Greg Sun, Richard A. Soref

Physics Faculty Publications

Local population inversion and far-IR gain are proposed and theoretically analyzed for an unbiased n-doped GaAs/Al0.15Ga0.85As superlattice pumped solely by phonons. The lasing transition occurs at the Brillouin zone boundary of the superlattice wave vector kzbetween the two conduction minibands CB1 and CB2 of the opposite curvature in kzspace. The proposed waveguided structure is contacted above and below by heat sinks at 300 K and 77 K, respectively. Atop the superlattice, a heat buffer layer confines longitudinal optical phonons for enhanced optical-phonon pumping of CB1 electrons. A gain of 345 cm …

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Kinetics Of Substitution Of Weakly Coordinating Nitrate By Chloride In (Η5-Cp)Ru(Co)(Er3)Ono2 (Er3 = Asph3, Pph3, P(P-Anisyl)3, Pph2(O-Anisyl), P(Oph)3) In Dichloromethane., Minhton Cao, Liem Do, Norris Hoffman, Man Lung Kwan, Julie Little, J. Mcgilvray, Christopher Morris, Bjorn Söderberg, Andrzej Wierzbicki, Thomas Cundari, Charles Lake, Edward Valente May 2001

Kinetics Of Substitution Of Weakly Coordinating Nitrate By Chloride In (Η5-Cp)Ru(Co)(Er3)Ono2 (Er3 = Asph3, Pph3, P(P-Anisyl)3, Pph2(O-Anisyl), P(Oph)3) In Dichloromethane., Minhton Cao, Liem Do, Norris Hoffman, Man Lung Kwan, Julie Little, J. Mcgilvray, Christopher Morris, Bjorn Söderberg, Andrzej Wierzbicki, Thomas Cundari, Charles Lake, Edward Valente

Man Lung Desmond Kwan

The d6 complexes of formula (η5-Cp)Ru(CO)(ER3)ONO2, where ER3 = AsPh3, PPh3, P(p-anisyl)3, PPh2(o-anisyl), and P(OPh)3, were prepared by reaction of their chloro analogues with AgNO3 in CH2Cl2. They underwent moderately slow substitution of the relatively weakly coordinating nitrate by chloride in dry CH2Cl2 in the presence of excess [N(PPh3)2+]Cl-. A kinetics study showed the reaction to be first order in nitrato complex and independent of chloride salt concentration under pseudo-first-order conditions. First-order rate constants for nitrate metathesis follow the trend P(OPh)3 < PPh3 < P(p-anisyl)3 < AsPh3 PPh2(o-anisyl), with k1 at 25 °C for the first four in the series from 1.4 to 4.4 × 10-5 s-1. Activation parameters for conversion of (η5-Cp)Ru(CO)(AsPh3)ONO2 to its chloride are ΔH‡ = 17(2) kcal/mol and ΔS‡ = −21(5) eu. Even use of a slightly moist solvent increased the rate of nitrate metathesis by 20−30% without changing the form of the rate law. The complex containing PPh2(o-anisyl) was approximately 2 orders of magnitude more reactive (k1 = 4.9 × 10-3 s-1). A likely explanation is stabilization of a coordinatively unsaturated intermediate by weak coordination of the potentially chelating o-OMe group. A mechanism entailing rate-limiting conversion of the neutral nitrato complex into a coordinatively unsaturated ion-paired species is consistent with this set of data. Semiempirical calculations (PM3(tm)), which model the structures of complexes in these systems quite well, supported such behavior. X-ray crystal structures were determined for the AsPh3 nitrato and chloro complexes and for the PPh3 chloro complex.

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Computer Simulations Of Confined Systems, Jayendran C. Rasaiah May 2001

Computer Simulations Of Confined Systems, Jayendran C. Rasaiah

University of Maine Office of Research Administration: Grant Reports

Jayendran Rasaiah of the University of Maine is supported by an award from the Theoretical and Computational Chemistry program with partial funding provided by the Experimental Program to Stimulate Competitive Research for the development of computational methods to simulate water and other solvents in confined systems, such as carbon nanotubes and the interior of proteins. Other systems which are being studied include capillary evaporation of water between hydrophobic plates, water near surfaces and water between charged membranes. The development of better water potentials for a variety of applications is a major goal of the research. Rasaiah is also developing efficient …

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