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Articles 29311 - 29340 of 34711

Full-Text Articles in Physical Sciences and Mathematics

Β-Silyl And Β-Germyl Carbocations Stable At Room Temperature, Joseph B. Lambert, Yan Zhao, Hongwei Wu Mar 1999

Β-Silyl And Β-Germyl Carbocations Stable At Room Temperature, Joseph B. Lambert, Yan Zhao, Hongwei Wu

Yan Zhao

Stable carbocations have been prepared at room temperature with benzene as solvent and tetrakis(pentafluorophenyl)borate (TPFPB) as anion by the addition of solvated triethylsilylium TPFPB or of tributylgermylium TPFPB to 1,1-diphenylethene. These carbocations are stabilized by σ conjugation with nonadjacent group 14 atoms and respectively constitute stable saturated β-silyl and β-germyl carbocations. NMR parameters, including the 29Si chemical shift, the 13C chemical shifts of the cationic, aryl, and methylene carbons, and the one-bond 13C−1H coupling constant of the methylene group adjacent to the group 14 element, define the distribution of positive charge between carbon and (through σ conjugation) silicon or germanium. …

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21. Teiji Tsuruta, Otto Vogl Mar 1999

21. Teiji Tsuruta, Otto Vogl

Otto Vogl

No abstract provided.

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Molecular Dynamics Study Of A Phase-Separating Fluid Mixture Under Shear Flow, Ryoichi Yamamoto, Xiao Cheng Zeng Mar 1999

Molecular Dynamics Study Of A Phase-Separating Fluid Mixture Under Shear Flow, Ryoichi Yamamoto, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Molecular dynamics simulation is carried out to study domain structures and rheological properties of a two-dimensional phase-separating binary fluid mixture under shear flow. In the early stage of the phase separation, anisotropic composition fluctuations appear immediately after the quench. As the domain grows, the anisotropy in the composition fluctuations increases. The quenched system eventually reaches a dynamical steady state, in which anisotropic domain structures are preserved. In the steady state, the shortest characteristic length scale R⊥ of domains decreases with increasing shear rate γ̇ as R⊥∼γ̇-1/3. Stringlike domain structures are observed in the strong shear regime, …

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Formation Free Energy Of Clusters In Vapor-Liquid Nucleation: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng Mar 1999

Formation Free Energy Of Clusters In Vapor-Liquid Nucleation: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The formation free energy of clusters in a supersaturated vapor is obtained by a constrained Monte Carlo technique. A key feature of this approach is to set an upper limit to the size of cluster. This maximum cluster size serves essentially as an extra thermodynamic variable that constrains the system. As a result, clusters larger than the critical cluster of nucleation in the supersaturated vapor can no longer grow beyond the limiting size. Like changing the overall density of the system, changing the maximum cluster size also results in a different supersaturation and thereby a different formation free energy. However, …

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Infrared Cavity Ringdown Spectroscopy Of Methanol Clusters: Single Donor Hydrogen Bonding, R. A. Provencal, J. B. Paul, K. Roth, C. Chapo, R. N. Casaes, R. J. Saykally, G. S. Tschumper, H. F. Schaefer Mar 1999

Infrared Cavity Ringdown Spectroscopy Of Methanol Clusters: Single Donor Hydrogen Bonding, R. A. Provencal, J. B. Paul, K. Roth, C. Chapo, R. N. Casaes, R. J. Saykally, G. S. Tschumper, H. F. Schaefer

Chemistry Faculty Research & Creative Works

Infrared cavity ringdown laser absorption spectroscopy has been used to study the O-H stretching vibrations of jet-cooled methanol clusters in direct absorption. Rovibrational bands for (CH3OH)2, (CH3OH)3, and (CH3OH)4 have been measured. Both bonded and free O-H stretches were measured for the dimer, indicating that its structure is linear. Five bands were assigned to the methanol trimer, indicating the presence of a second cyclic isomer in the molecular beam. A detailed study of the free O-H stretching region shows that methanol clusters larger than dimer must exist in cyclic …

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Tga/Ftir Studies On The Thermal Degradation Of Some Polymeric Sulfonic And Phosphonic Acids And Their Sodium Salts, David D. Jiang, Qiang Yao, Michael A. Mckinney, Charles Wilkie Mar 1999

Tga/Ftir Studies On The Thermal Degradation Of Some Polymeric Sulfonic And Phosphonic Acids And Their Sodium Salts, David D. Jiang, Qiang Yao, Michael A. Mckinney, Charles Wilkie

Chemistry Faculty Research and Publications

The thermal degradation of poly(vinyl sulfonic acid) and its sodium salt, poly(4-styrenesulfonic acid) and its sodium salt, and poly(vinylphosphonic acid) was studied by a combination of techniques, including TGA/FTIR, to identify the volatile products which were evolved during the degradation as well as analysis of the residues which were obtained in order to propose a mechanism for the degradation. The motivation for the work was to attempt to identify new monomers which could be graft copolymerized onto a polymer in order to improve the thermal stability of that polymer.

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Study On The Mechanism Of Ni/Zro 2 Composite Electrodeposition, Qunjia Peng, Daobin Mu, Jusheng Ma, Xiangyun Tang Feb 1999

Study On The Mechanism Of Ni/Zro 2 Composite Electrodeposition, Qunjia Peng, Daobin Mu, Jusheng Ma, Xiangyun Tang

Journal of Electrochemistry

The effects of cathodic current density and amount of particle dispersion in solution on the codeposition of Ni/ZrO 2 composite in Watts bath were studied, and the machanism of the composite electrodeposition was investigated.The study shows that the composite electrodeposition is controlled by the transfer of particles to the cathode when the dispersion amount is small, causing the decrease of the codeposition with the increase of current density. With large amount dispersion,the composite electrodeposition is first controlled by the strong adsorption of particles on the cathode at low current density, resulting in the increase of the codeposition with the increase …

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Pitting Corrosion Of Ni_Based Alloy In Thiosulfate_Ion Containing Chloride Solutions, Yungfa Lee, Tingyu Wang, Wenta Tsai Feb 1999

Pitting Corrosion Of Ni_Based Alloy In Thiosulfate_Ion Containing Chloride Solutions, Yungfa Lee, Tingyu Wang, Wenta Tsai

Journal of Electrochemistry

The effect of thiosulfate ion on the pitting corrosion behavior of Ni_Based Alloy 690 in chloride solution was investigated.In plain sodium thiosulfate solution,Alloy 690 was immune to pitting corrosion. However, the addition of low concentration of sodium thiosulfate can enhance the initiation of pitting corrosion of Alloy 690. Nevertheless, inhibition of pitting corrosion was observed at high concentration of addition.

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Synthesis And Application Of Polymeric Corrosion Inhibitor For Reinforced Concrete, Weiwei Lin, Shengxian Wang, Jianqing Zhang Feb 1999

Synthesis And Application Of Polymeric Corrosion Inhibitor For Reinforced Concrete, Weiwei Lin, Shengxian Wang, Jianqing Zhang

Journal of Electrochemistry

A new polymer E Twas synthesized and used as a corrosion inhibitor for reinforced concrete. The inhibitive behavior and mechanism were studied with linear polarization ,Tafel polarization,EIS and XPS method in simulated pore solution system with concrete samples.The result showed that the polymer was a mixing type inhibitor. A 1% dosage was sufficient to imhibit the corrosion of steel in simulated pore solution system. The salt endurance was enhanced from 0.02 mol/L to 0.10 mol/L.The result also showed the good synergetic effect of NaNO 2,especially in low NaNO 2 concentration.The EIS showed that E_T has dual function on reinforced concrete,i.e.,densifying …

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Study Of Localized Corrosion Of Metals By Using The Electrochemical Techniques With Spatial Resolution, Changjian Lin, Xiangdong Zhuo, Zude Feng, Ronggui Du, Zhaowu Tian Feb 1999

Study Of Localized Corrosion Of Metals By Using The Electrochemical Techniques With Spatial Resolution, Changjian Lin, Xiangdong Zhuo, Zude Feng, Ronggui Du, Zhaowu Tian

Journal of Electrochemistry

The electrochemical inhomogeneities at interface of metal/solution play an important and often controlling role in localized corrosion of metals.The traditional electrochemical techniques involving potential,current density or ac impedance measurements over bulk specimens can only provide average and general information of the interface. Thus, the development of in situ imaging techniques is essential for further characterizing electrochemical inhomogeneities at the metal/solution interface of localized corrosion system.The electrochemical techniques with spatial resolution,including scanning single micro electrode,scanning double micro electrodse and scanning micro chemical probes are reviewed.The effects of electrochemical inhomogeneities on the corrosion behavior,and the mechanism fot various localized corrosion of metals …

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Some Effects Of Co On The Electrochromic Properties Of Nio Xh Y Film, Xiaoyan Cao, Wenhu Zhang, Huatang Yuan, Wanlin Zhang, Yinnong Lin, Zuoxiang Zhang Yunshi Zhou Feb 1999

Some Effects Of Co On The Electrochromic Properties Of Nio Xh Y Film, Xiaoyan Cao, Wenhu Zhang, Huatang Yuan, Wanlin Zhang, Yinnong Lin, Zuoxiang Zhang Yunshi Zhou

Journal of Electrochemistry

Some effects of Co addition upon the electrochromic characteristics of a nic_kel hydroxide film were studied. The films were electrodeposited on both polished Ni plate and conductive ITO glass. The electrochemical behaviors were investigated using the film on Ni plate by linear potential sweep, a.c. impedance, and anodic polarization curves for OER(oxygen evolution reaction). It was found that Co can lower the working voltage and raise the oxygen overpotential, but has little effect on the reaction kinetics. It was also found that the Co can improve the optical properties of the electrochromic film.

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Electrodeposition Of Neodymium_Iron Group Alloy Films In( P _Ch 3c 6h 4so 3) 3nd+Dmf System, Peng Liu, Yexiang Tong, Qiqin Yang, Yansheng Yang Feb 1999

Electrodeposition Of Neodymium_Iron Group Alloy Films In( P _Ch 3c 6h 4so 3) 3nd+Dmf System, Peng Liu, Yexiang Tong, Qiqin Yang, Yansheng Yang

Journal of Electrochemistry

Neodymium p _toluenesulfonate was prepared and applied to the electrodepositon of neodymium_iron group alloy films. This salt has high solubility in DMF and can be dehydrated easily. Cyclic voltammograms of Pt electrode in ( p _CH 3C 6H 4SO 3) 3Nd+MCl 2(M=Fe,Co,Ni)+DMF indicated that the neodymiun_iron group alloys can be elcetrodeposited from this medium, the Nd_Fe,Nd_Co and Nd_Ni films were obtained by electrolysis at constant potential. The Nd_Fe,Nd_Co and Nd_Ni films are amorphous in which the rare earth contents are in the range of 15 at%～60 at% as analyzed by XRD and EDS. The Nd content in the deposited film …

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Oxidation Mechanism Of Hypophosphite, Dongbai Sun, Ying Jin, Hongying Yu, Dejun Yang Feb 1999

Oxidation Mechanism Of Hypophosphite, Dongbai Sun, Ying Jin, Hongying Yu, Dejun Yang

Journal of Electrochemistry

There exist two oxidation current peaks on the anodic polarization curve between -0.7 V and 0 V(SCE) in Na_hypophosphite solution. Peak Ⅰ (-0.55 V, SCE) , which represents the oxidation process from H 2PO - 2 to H 2PO - 3, has been studied previously. Peak Ⅱ, which is located at the potential about -0.4 V(SCE), is investigated emphatically in this paper. The results show that, peak Ⅰ and Ⅱ are corresponding to two successive steps in oxidation process of H 2PO - 2, i.e. peak Ⅱ corresponds to the oxidation process of adsorped (HPO 2) ads , an intermediate …

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Effect Of Stress On Electrochemical Behaviour Of Various Thermal History Zones And Different Phase Structures On The Weldment For Low Alloy Steel, Yinshun Wu, Deyu Liu, Bei Cao, Fengli Wang, Zhi Fang, Lin Zhang, Zhengrong Zhang, Hai Yang Feb 1999

Effect Of Stress On Electrochemical Behaviour Of Various Thermal History Zones And Different Phase Structures On The Weldment For Low Alloy Steel, Yinshun Wu, Deyu Liu, Bei Cao, Fengli Wang, Zhi Fang, Lin Zhang, Zhengrong Zhang, Hai Yang

Journal of Electrochemistry

The electrochemical behaviour of various thermal history zones on the weldment for steel 16Mn and also of the ferrite,pearlite in various zones was measured by use of a self-developed measuring technique for investigating the electrochemicl behaviour of single and mixed phase structures in metal materials.Especially the effect of stress on this electrochemical behaviour was investigated.The results showed that by comparison with non-stress condition,the free corrosion potential of the various thermal history zones and of the ferrite,pearlite under stress condition was shifted in negative direction,correspondingly their free corrosion current density was increased,the free corrosion potential difference between ferrite and pearlite was …

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Study On Steel Corrosion In Simulated Biofilm Environment In Seawater, Qingfei Wang, Jing Sui, Runxi Su, Deying Kong, Shizhe Song Feb 1999

Study On Steel Corrosion In Simulated Biofilm Environment In Seawater, Qingfei Wang, Jing Sui, Runxi Su, Deying Kong, Shizhe Song

Journal of Electrochemistry

Biofilm is one of the main factors that influence metal corrosion in seawater environment. According to the structure and property of biofilm, a natural biopolymeric gel,calcium alginate(an extracellular biopolymer containing carboxylate functional groups) can deposite on metal surfaces to form films. Corrosion behavior of alloyed steel E 2, 10CrMoAl and 18_8 stainless steel were studied in simulated biofilm environment by various electrochemical methods,including measurements of the corrosion potential,polarization curves,galvanic current and electrochemical impedance.The results show that such an approach is informative to reveal “how” and “to what extent” biofilm can influence the metal corrosion process.

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Structural And Electrochemical Studies On Todorokite/Vernadite As Cathodes For Rechargeable Lithium Ion Batteries, Wei Chu, Deyao Liu, Jinkua You, Yong Yang, Zugeng Lin Feb 1999

Structural And Electrochemical Studies On Todorokite/Vernadite As Cathodes For Rechargeable Lithium Ion Batteries, Wei Chu, Deyao Liu, Jinkua You, Yong Yang, Zugeng Lin

Journal of Electrochemistry

XRD,TEM,ICP,low scan_rate CV and charge/discharge tests were carried out for the studies on the structural and electrochemical behavior of a prepared 3 V manganese oxide cathode for rechargeable lithium ion batteries.XRD analysis revealed that the cathode sample is mainly composed of tunneled Todorokite and layered Vernadite.TEM investigation confirmed that the morphology of the sample is a laminated construction with approximate 10nm layer space.The reversibility of Li + removal/intercalation and structural stability of this sample framework to lithium insertion are good in CV and charge/discharge tests. The discharge capacities were found to be about 129mAh/g obtained on first 30 cycles and …

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Study Of Electrochemistry Of Tetrasulphonated Phthalocyanine Zinc In Aqueous And Nonaqueous Solvents, Ersheng Liu, Yiqun Wu, Jianhui Yang, Liying Huang, Jundong Wang, Suling Yang, Naisheng Chen, Jinling Huang Feb 1999

Study Of Electrochemistry Of Tetrasulphonated Phthalocyanine Zinc In Aqueous And Nonaqueous Solvents, Ersheng Liu, Yiqun Wu, Jianhui Yang, Liying Huang, Jundong Wang, Suling Yang, Naisheng Chen, Jinling Huang

Journal of Electrochemistry

The voltammetry of Tetra_sulphonated phthalocyanine Zn(TSPcZn)in DMSO and DMF solution has been examined and compared with those obtained in aqueous solution.The results showed that three pairs of redox peaks were appear in non_aqueous solvents,exhibiting three quasi_reversible phthalocyanine ligand based one_electron transfers,while in aqueous solution did no quasi_reversible behaviour was observed. The photoelectrochemical effect of light on TSPcZn redox reactions were also discussed.

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Studies Of Electrochemical Characteristics Of Pasted Nickel Hydroxide Electrode With Surface Deposited Cobalt, Xianyou Wang, Yunshi Zhang, Jie Yan, Zheng Zhu, Huatang Yuan, Deying Song Feb 1999

Studies Of Electrochemical Characteristics Of Pasted Nickel Hydroxide Electrode With Surface Deposited Cobalt, Xianyou Wang, Yunshi Zhang, Jie Yan, Zheng Zhu, Huatang Yuan, Deying Song

Journal of Electrochemistry

The surface of the spherical nickel hydroxide particles used as an active material in pasted nickel electrodes is surface_deposited with cobalt. This paper investigated the effects of the amount of cobalt deposit on the characteristics of nickel hydroxide electrode. The performances of the electrode, such as discharge capacity, utilization of active material and reversibility of Ni(OH) 2/NiOOH redox reaction, were studied by comparing the charging/discharging curves and cyclic voltammograms. The mechanism of action of cobalt deposits has been described in terms of the electrochemical impedance spectroscopy of nickel hydroxide electrode.

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Study On Ionic Conductivity Of A Novel Solid State Electrolyte, Yingxin Zhao, Changyan Liu Feb 1999

Study On Ionic Conductivity Of A Novel Solid State Electrolyte, Yingxin Zhao, Changyan Liu

Journal of Electrochemistry

Various novel predominantly lithium_ion_conducting solid state electrolytes were described, which had high conductivity at room temperature. It comprised low_melting_point eutectic lithium salts in which a small amount of an single ion polyeletrolyte poly(lithium acrylate) was dissolved to rubberize them. The effects of the eutectic and polymer features upon the ionic conductivity were discussed.

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Electrohydrodimerization Of Fumarodinitrile On Liquid Gallium Electrode, He Wei, Huang Ying Feb 1999

Electrohydrodimerization Of Fumarodinitrile On Liquid Gallium Electrode, He Wei, Huang Ying

Journal of Electrochemistry

Electrohydrodimerization(EHD) of fumarodinitrile on liquid gallium electrode can take place not only in hydrotropic solution of tetraethylammonium p_toluenesulphonate(TEA_PTS), but also in aqueous solution containing low concentration of strong surfactants, such as TritonX_100. In solution without organic surfactant, FDN yields a single two_electron reduction wave corresponding to the formation of a saturated monomer called as butanedinitrile. If some TEA_PTS or TritonX_100 is added into the solution, the original two_electron wave is splitted into two continuous single_electron reduction wave and corresponding EHD of fumarodinitrile is obtained.

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Electrochemical Surface Characterization Of Titanium Alloy(Ti_6al_4v)), Jianzhong Chen, Qingliang Gao, Zhongyi Wang, Wenjing Xue Feb 1999

Electrochemical Surface Characterization Of Titanium Alloy(Ti_6al_4v)), Jianzhong Chen, Qingliang Gao, Zhongyi Wang, Wenjing Xue

Journal of Electrochemistry

With its low density and high strength ratio, titanium alloy(Ti_6Al_4V) has become one of the most important materials both in the fields of aerospace and biomedical assays. Recently, titanium alloy was used as the implantation materials in human body because of its biocompatibility. The elecrochemical impedance techniques were then used to investigate the corrosion behavior of this material in hydrochloride and sulfuric acid solutions. A comparison between impedance spectra and anodic polarization over the correlated range of applied voltage confirms that AC impedance data can be used as a powerful tool for surface characterization of titanium alloy.

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Kinetic Study Of Electrooxidation Of Benzene, Xinsheng Ding Ping Zhang, Yingchun Dai, Weikang Yuan Feb 1999

Kinetic Study Of Electrooxidation Of Benzene, Xinsheng Ding Ping Zhang, Yingchun Dai, Weikang Yuan

Journal of Electrochemistry

A reaction kinetic study for electrochemical oxidation of benzene was performed on a PbO 2 rotating disk electrode in 1 mol/L H 2SO 4 aqueous solution. The reaction orders, the activation energies and transfer coefficient were measured, and the kinetic expression was obtained.

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A New Cell Structure For Proton Exchange Membrane Fuel Cell, Ming Han, Hongfeng Xu, Baolian Yi Feb 1999

A New Cell Structure For Proton Exchange Membrane Fuel Cell, Ming Han, Hongfeng Xu, Baolian Yi

Journal of Electrochemistry

Separating the functions of current collection and gas flow distribution and then to design two separate elements to achieve the desired performance characteristics,a nonconventional cell structure for proton exchange membrane fuel cells bave been developed.The current collector is achieved using a thin stain steel sheet,the gas flow distribution is achieved using a carbon paper that has the desired chemical durabiliy when in contact with the proton exchange membrane. Combining these two separate elements into a single divice yields a bifunctional device that performs as a bipolar separator plate. The advantages of this alternative appproach to making biplar plates are that …

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Macrocyclic Antibiotics As Separation Agents, Daniel W. Amstrong Feb 1999

Macrocyclic Antibiotics As Separation Agents, Daniel W. Amstrong

Chemistry Faculty Research & Creative Works

Macrocyclic antibiotics having ring structures with at least 10 members act as separation agents in crystallization, precipitation, filtration, electrophoresis and chromatography. The macrocyclic antibiotics include ansamacrolides, macrolides, marocyclic peptides, polyenes and derivatives thereof. The process has been found to be especially advantageous for separation of optical isomers by electrophoresis and chromatography.

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Valence-Band Electronic Structure Of Co3O4 Epitaxy On Coo(100), Marjorie Langell, M.D. Anderson, G.A. Carson, L. Peng, S. Smith Feb 1999

Valence-Band Electronic Structure Of Co3O4 Epitaxy On Coo(100), Marjorie Langell, M.D. Anderson, G.A. Carson, L. Peng, S. Smith

Marjorie A. Langell Publications

Valence-band photoemission studies have been performed on a CoO(100) single crystal as it is slowly oxidized under 1×10-4 Torr O2 at 623 K, eventually forming a Co3O4 epitaxial film. The most significant changes occur in 3d-related features, with the peak located at the top of the valence band sharpening and shifting to lower binding energies as the spinel oxide forms. Constant initial-state measurements indicate that Co3O4 contains admixture from neighboring O 2p in its 3d band, as observed for CoO and other monoxide charge-transfer insulators. Unlike the rocksalt …

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[2,3:5,6]Dibenzo[2.2.2]Octa-2,5,7-Triene (C2/C) And [2,3:5,6]Dibenzo[2.2.2]Octa-2,5-Diene, Lary Burrows, John M. Masnovi, Ronald J. Baker Feb 1999

[2,3:5,6]Dibenzo[2.2.2]Octa-2,5,7-Triene (C2/C) And [2,3:5,6]Dibenzo[2.2.2]Octa-2,5-Diene, Lary Burrows, John M. Masnovi, Ronald J. Baker

Chemistry Faculty Publications

Two barrelene homologs are reported. Strain in the bicyclic framework of [2,3:5,6]dibenzo[2.2.2]octa-2,5,7- triene, (I) (C16H12), which is manifest in the deviations from ideality of the bond angles in the central bicyclic ringoSyStem and compression of the double bond [1.312 (3)A], is reduced in the more saturated derivative, [2,3:5,6]dibenzo[2.2.2]octa-2,5-diene, (II) (CI6H14), with the corresponding single bond being 1.5380 (19)A. The formation of isomorphs of (I) in both chiral (C2) and achiral (C2/c) space groups has implications for asymmetric syntheses involving solid (I) which rely on a non-centrosymmetric space group.

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Thermodynamic Expansion Of Nucleation Free-Energy Barrier And Size Of Critical Nucleus Near The Vapor-Liquid Coexistence, Kenichiro Koga, Xiao Cheng Zeng Feb 1999

Thermodynamic Expansion Of Nucleation Free-Energy Barrier And Size Of Critical Nucleus Near The Vapor-Liquid Coexistence, Kenichiro Koga, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Nucleation free-energy barrier height and size of the critical nucleus are expanded in powers of the chemical potential difference between the supersaturated vapor (or expanded liquid) in the metastable state and the saturated vapor-liquid system in the stable equilibrium state at the same temperature. The coefficients in the expansions are expressed in terms of the thermodynamic properties at the stable equilibrium state. Comparisons with the results obtained from the density-functional calculation for nucleation of the Lennard–Jones fluid show that systematic improvement in predicting properties of the critical nucleus, either liquid droplet or vapor cavity, is achieved by adding the higher …

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Cumulative Reaction Probability In Terms Of Reactant-Product Wave Packet Correlation Functions, Sophya Garashchuk, David J. Tannor Feb 1999

Cumulative Reaction Probability In Terms Of Reactant-Product Wave Packet Correlation Functions, Sophya Garashchuk, David J. Tannor

Faculty Publications

Presents expressions for the cumulative reaction probability (N(E)), cast in terms of time-correlation functions of reactant and product wave packets. Beginning of the derivation with a standard trace expression for the cumulative reaction probability; Expression for N(E) obtained in terms of the correlation matrices of incoming and outgoing wave packets.

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Langmuir Monolayers As Disordered Solids: Strain-Tilt-Backbone Coupling And Natural Order Parameters For The Swiveling Transitions, Tadeusz Luty, David R. Swanson, Craig J. Eckhardt Feb 1999

Langmuir Monolayers As Disordered Solids: Strain-Tilt-Backbone Coupling And Natural Order Parameters For The Swiveling Transitions, Tadeusz Luty, David R. Swanson, Craig J. Eckhardt

Craig J. Eckhardt Publications

Multistability of Langmuir monolayers, in particular those composed of fatty acids, is reflected by a very rich and complicated phase diagram. We argue that strain-tilt-backbone coupling determines the behavior described by that diagram. Following the solid state approach, we show that a natural order parameter set is defined by thermal averages of spherical harmonics and strain tensor components. In addition, we show that the backbone order parameter can be conveniently represented by an elastic dipole tensor. Treating Langmuir monolayers as disordered solids, we have derived an orientational entropy contribution to the free energy. The swiveling transition between L2 ( …

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Effect Of Uniform Electric Field On Homogeneous Vapor–Liquid Nucleation And Phase Equilibria. Ii. Extended Simple Point Charge Model Water, G.T. Gao, K.J. Oh, Xiao Cheng Zeng Feb 1999

Effect Of Uniform Electric Field On Homogeneous Vapor–Liquid Nucleation And Phase Equilibria. Ii. Extended Simple Point Charge Model Water, G.T. Gao, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The effects of a uniform electric field on homogeneous vapor–liquid nucleation of the extended simple point charge (SPC/E) model water have been simulated. A grand canonical Monte Carlo simulation approach [I. Kusaka et al., J. Chem. Phys. 108, 3416 (1998)], which directly gives the equilibrium distribution of physical clusters, is employed to calculate the formation free energy of the SPC/E water cluster. The results show that the formation free energy is lowered in a uniform field if the chemical potential of the supersaturated vapor is fixed; in this case, the field enhances the rate of nucleation. However, if the vapor …

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