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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
The Effect Of A Uniform Electric Field On Homogeneous Vapor–Liquid Nucleation In A Dipolar Fluid. I. Stockmayer Fluid, K.J. Oh, G.T. Gao, Xiao Cheng Zeng
The Effect Of A Uniform Electric Field On Homogeneous Vapor–Liquid Nucleation In A Dipolar Fluid. I. Stockmayer Fluid, K.J. Oh, G.T. Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
The rate of homogeneous vapor–liquid nucleation is controlled mainly by the Gibbs formation free energy of critical clusters. Within the framework of thei/υ cluster theory of Reiss and co-workers, the formation free energies of Stockmayer clusters in the presence of a uniform electric field are determined. The Helmholtz free energy of the clusters, an input required in the i/υ cluster theory, is calculated via Monte Carlo simulations. The most significant result is that as a uniform electric field is applied the formation free energy at fixed supersaturation of the vapor becomes larger than that in the absence …
Validity Of Tolman’S Equation: How Large Should A Droplet Be?, Kenichiro Koga, Xiao Cheng Zeng, A.K. Shchekin
Validity Of Tolman’S Equation: How Large Should A Droplet Be?, Kenichiro Koga, Xiao Cheng Zeng, A.K. Shchekin
Xiao Cheng Zeng Publications
Surface tension and the length δ (distance between the Gibbs surface of tension Rs and the equimolar surface Re) of simple liquid droplet (Lennard-Jones and Yukawa) are computed over a wide range of droplet sizes up to about 4x106 molecules. The study is based on the Gibbs theory of capillarity combined with the density–functional approach to gas–liquid nucleation. Since this method provides behavior of the surface tension fully consistent with the tension of the planner surface, the constant in Tolman’s equation δx can be determined unequivocally from the asymptotic behavior of σ s . Comparison …
Orientation Of Nickelocene On Ag(100), D. L. Pugmire, C. M. Woodbridge, Marjorie Langell
Orientation Of Nickelocene On Ag(100), D. L. Pugmire, C. M. Woodbridge, Marjorie Langell
Marjorie A. Langell Publications
High-resolution electron-energy-loss spectroscopy has been used to study the molecular adsorption of nickelocene, Ni(C5H5)2, on Ag(100). Results indicate that at up to one monolayer coverage, nickelocene adsorbs molecularly with its axis approximately perpendicular to the surface. At very high coverages, the molecular axis is not exclusively oriented along the surface normal. This is possibly due to randomization of the metallocene orientation as multilayers are formed.
Selective Determination Of Methylmercury By Flow-Injection Fast-Scan Voltammetry, Rebecca Lai, Eva Huang, Feimeng Zhou, David O. Wipf
Selective Determination Of Methylmercury By Flow-Injection Fast-Scan Voltammetry, Rebecca Lai, Eva Huang, Feimeng Zhou, David O. Wipf
Rebecca Lai Publications
A simple flow-injection system, suitable for solution flow rates at microliters-per-minute, has been combined with fast-scan voltammetry for selective determination of methylmercury. A thin Hg film was formed at a Pt microelectrode prior to the measurement. Detection of methylmercury is carried out by measuring the oxidation of methylmercury radicals that have been generated at the Hg microelectrode. At slow scan rates, the electrogenerated methylmercury radicals undergo a follow-up dimerization reaction to form dimethyldimercury (ErCi2 mechanism). At fast scan rates, it was found that methylmercury radicals can be quantitatively reoxidized (reversible electron-transfer). Optimization of the experimental conditions …
Covalently Functionalized Nanotubes As Nanometer-Sized Probes In Chemistry And Biology, Stanislaus S. Wong, Ernesto Joselevich, Adam T. Woolley, Chin Li Cheung, Charles M. Lieber
Covalently Functionalized Nanotubes As Nanometer-Sized Probes In Chemistry And Biology, Stanislaus S. Wong, Ernesto Joselevich, Adam T. Woolley, Chin Li Cheung, Charles M. Lieber
Barry Chin Li Cheung Publications
Carbon nanotubes combine a range of properties that make them well suited for use as probe tips in applications such as atomic force microscopy (AFM)1, 2, 3. Their high aspect ratio, for example, opens up the possibility of probing the deep crevices4 that occur in microelectronic circuits, and the small effective radius of nanotube tips significantly improves the lateral resolution beyond what can be achieved using commercial silicon tips5. Another characteristic feature of nanotubes is their ability to buckle elastically4, 6, which makes them very robust while limiting the maximum force that is …
Single Crystal Raman Spectra Of 1,2,4,5-Tetrabromobenzene: Calculational And Experimental Assignment Of The Internal Modes, K.M. White, Craig J. Eckhardt
Single Crystal Raman Spectra Of 1,2,4,5-Tetrabromobenzene: Calculational And Experimental Assignment Of The Internal Modes, K.M. White, Craig J. Eckhardt
Craig J. Eckhardt Publications
A detailed study of the fundamental internal modes of the 1,2,4,5-tetrabromobenzene crystal has provided assignments of Raman-active modes consistent with polarized single-crystal measurements. A normal-mode calculation based on a valence force field derived from brominated and chlorinated benzenes is found to be in excellent agreement with the assignments. Additional bands arising from anharmonic interactions of the fundamentals are also assigned.
Structure And Lattice Dynamics Of Dipolarly Disordered 2,3-Dimethylanthracene Crystals, M. Dörr, H. Gerlach, J. Kalus, N. Karl, M. Monkenbusch, I. Natkaniec, U. Schmelzer, W. Schmidt, John J. Stezowski, P. Vorderwisch, M. Warth
Structure And Lattice Dynamics Of Dipolarly Disordered 2,3-Dimethylanthracene Crystals, M. Dörr, H. Gerlach, J. Kalus, N. Karl, M. Monkenbusch, I. Natkaniec, U. Schmelzer, W. Schmidt, John J. Stezowski, P. Vorderwisch, M. Warth
John J. Stezowski Publications
2,3-dimethylanthracene (2,3-DMA, C16H14) crystallizes in a pseudocentrosymmetric triclinic lattice with two molecules per unit cell showing dipolar structural disorder of the acentric molecules. Using powder samples the amplitude weighted phonon density of states was measured by inelastic incoherent neutron scattering for different degrees of deuteration. The differences in the resulting spectra can be explained by changes of the dynamics of the molecular bodies or the methyl side groups. By the method of inelastic coherent neutron scattering phonon dispersion curves were determined. The phonon lines are broad even at low temperatures; this fact is supposed to be …
Contribution Of The Center-Of-Mass Fluctuation Of A Liquid Cluster To The Free Energy: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng
Contribution Of The Center-Of-Mass Fluctuation Of A Liquid Cluster To The Free Energy: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
The contribution of the center-of-mass (CM) fluctuation of a liquid cluster to the Helmholtz free energy was first discussed by Reiss, Katz, and Cohen (RKC). They argued that this contribution can be assessed via the free energy difference between the cluster with a fixed boundary centered on a fixed CM, and the cluster in which the CM was allowed to fluctuate. They estimated the free energy difference is to be about 20 kbT. Here kb is the Boltzmann constant and T is the temperature of the system. To examine this estimate, Abraham et al. later calculated …
D/H Exchange In Nitro Diastereomers, Charles A. Kingsbury
D/H Exchange In Nitro Diastereomers, Charles A. Kingsbury
Chemistry Department: Faculty Publications
The two diastereomers of 4-nitro-1,3-diphenylpentan-1-one behave differently in deuterium for hydrogen exchange in DMSO-d6/D2O solutions using various bases as catalyst. Reaction of the erythro diastereomer gives largely the same diastereomer upon D/H exchange (retention), i.e., exchange exceeds epimerization. Pyridine and acetonitrile as solvents lead to faster epimerization than exchange. In the threo diastereomer (DMSO-d6 solution), epimerization exceeds exchange, and the anion to some extent regains the same hydrogen originally removed by the base on the opposite face. 2-Bromo-4-nitro-1,3-diphenylbutan-1-one undergoes ring closure to the cyclopropane faster than exchange (within seconds). The cyclopropane shows faster exchange than equilibration, i.e., retention of configuration, …
Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke
Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke
Chemistry Department: Faculty Publications
A novel Zerovalent zinc species and an organozinc reagent are disclosed. The zerovalent zinc species is directly pro duced by reaction of a reducing agent on a zinc salt, preferably Zn(CN)2. The organozinc reagent results from the reaction of the zerovalent zinc species and an organic compound having one or more stable anionic leaving groups. These organozinc reagents include a wide spectrum of functional groups in the organic radical, and are useful in a variety of reactions schemes.
Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke
Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke
Chemistry Department: Faculty Publications
Cross-coupling or addition reactions of organic compounds, including acid halides, allylic halides, and C.B-unsaturated carbonyl containing compounds, with organozinc com pounds may be readily and Safely carried out in the presence of cuprous iodide. The use of this catalyst in the coupling reaction provides for the preparation of commercially useful products in the pharmaceutical, agrochemical and other industries.
Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson
Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson
Chemistry Department: Faculty Publications
Ring-closing metathesis of jasmonate esters is shown to provide a rapid entry to jasmonate lactones. The lactones were investigated as possible quorum sensing molecules for the fungi Candida albicans. Assays demonstrated no effect on fungal morphology at concentrations up to 96 mM.
Method For The Synthesis Of Α-Oxranyl Amino Acids, David B. Berkowitz, Michelle L. Pedersen
Method For The Synthesis Of Α-Oxranyl Amino Acids, David B. Berkowitz, Michelle L. Pedersen
Chemistry Department: Faculty Publications
The present invention is related to a novel class of decar-boxylase enzyme inhibitors consisting of α-oxiranyl amino acids and derivatives thereof and a method of synthesizing Such compounds.
Pyrrolic Compounds, Michael J. Therien, Stephen Dimagno
Pyrrolic Compounds, Michael J. Therien, Stephen Dimagno
Chemistry Department: Faculty Publications
Novel methylpyrroles are provided, as well as processes for their preparation.