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Articles 27151 - 27180 of 34731

Full-Text Articles in Physical Sciences and Mathematics

The Melting Lines Of Model Silicon Calculated From Coexisting Solid–Liquid Phases, S. Yoo, Xiao Cheng Zeng, James R. Morris Jan 2004

The Melting Lines Of Model Silicon Calculated From Coexisting Solid–Liquid Phases, S. Yoo, Xiao Cheng Zeng, James R. Morris

Xiao Cheng Zeng Publications

The melting line is an important thermodynamic property of materials and can be calculated via computer simulation, given the intermolecular potential for the materials. Conventionally, the free-energy method has been mainly employed to calculate the melting line. Alternatives to the free-energy method for calculating the melting line include simulation of the solid-liquid coexistence and nonequilibrium molecular dynamics (MD) method. Recently, one of us (Morris) and Song reported a detailed simulation procedure to calculate the melting line of the Lennard-Jones system. Specifically, the MD simulation consists of a preparation run and a production run. In the preparation run, the liquid and …


Energy Conserving Approximations To The Quantum Potential: Dynamics With Linearized Quantum Force, Sophya Garashchuk, Vitaly A. Rassolov Jan 2004

Energy Conserving Approximations To The Quantum Potential: Dynamics With Linearized Quantum Force, Sophya Garashchuk, Vitaly A. Rassolov

Faculty Publications

Solution of the Schrödinger equation within the de Broglie–Bohm formulation is based on propagation of trajectories in the presence of a nonlocal quantum potential. We present a new strategy for defining approximate quantum potentials within a restricted trial function by performing the optimal fit to the log-derivatives of the wave function density. This procedure results in the energy-conserving dynamics for a closed system. For one particular form of the trial function leading to the linear quantum force, the optimization problem is solved analytically in terms of the first and second moments of the weighted trajectory distribution. This approach gives exact …


Hypothetical Thermodynamic Properties: The Boiling And Critical Temperatures Of Polyethylene And Polytetrafluoroethylene, James S. Chickos Jan 2004

Hypothetical Thermodynamic Properties: The Boiling And Critical Temperatures Of Polyethylene And Polytetrafluoroethylene, James S. Chickos

James Chickos

No abstract provided.


Methods Development And Application Of Two Dimensional Chromatography And Tandem Mass Spectrometry In Proteomics, Brett Romain Wenner Jan 2004

Methods Development And Application Of Two Dimensional Chromatography And Tandem Mass Spectrometry In Proteomics, Brett Romain Wenner

University of Kentucky Doctoral Dissertations

Although molybdenum blue solutions have been known for more than twocenturies, an understanding of their chemical nature is only beginning to emerge.This dissertation aimed at elucidating the structural nature of the polydisperse,nanoscopic components in the solution phases and the solid states of partiallyreduced polyoxomolybdate (Mo-POM). The study offered at least fourcontributions to the area: (1) a rational protocol for the molecular recognition ofMo-POM with de novo organic hosts. (2) demonstration of kinetic precipitation ofa dynamic mixture of polyoxomolybdates and application of the technique to thestudy of the dynamic mixture by TEM (3) characterization of the Mo-POMnanostructures by an unusual combination …


Solvent-Free Conversion Of Alpha-Naphthaldehyde To 1-Naphthoic Acid And 1-Naphthalenemethanol: Application Of The Cannizzaro Reaction, John J. Esteb, Keith M. Glogorich, Stacey A. O'Reilly Jan 2004

Solvent-Free Conversion Of Alpha-Naphthaldehyde To 1-Naphthoic Acid And 1-Naphthalenemethanol: Application Of The Cannizzaro Reaction, John J. Esteb, Keith M. Glogorich, Stacey A. O'Reilly

Scholarship and Professional Work - LAS

The Cannizzaro reaction is routinely covered in organic textbooks, but owing to the shortage of suitable procedures for the undergraduate teaching laboratory, this reaction is seldom performed in a first-year organic chemistry class. In this experiment, powdered potassium hydroxide and α-naphthaldehyde are heated under solvent-free conditions to produce 1-naphthoic acid and 1-naphthalenemethanol in 86% and 79% yields, respectively. The solvent-free nature of this procedure greatly reduces the quantity of waste generated by students relative to the typical solvent-based method of preparation. Note:Link is to the article in a subscription database available to users affiliated with Butler University. Appropriate login information …


Distributions Of Z-Dna And Nuclear Factor I In Human Chromosome 22: A Model For Coupled Transcriptional Regulation, P. Christoph Champ, Sandor Maurice, Jeff Vargason, Tracy Camp, P. Shing Ho Jan 2004

Distributions Of Z-Dna And Nuclear Factor I In Human Chromosome 22: A Model For Coupled Transcriptional Regulation, P. Christoph Champ, Sandor Maurice, Jeff Vargason, Tracy Camp, P. Shing Ho

Faculty Publications - Department of Biological & Molecular Science

An analysis of the human chromosome 22 genomic sequence shows that both Z-DNA forming regions (ZDRs) and promoter sites for nuclear factor-I (NFI) are correlated with the locations of known and predicted genes across the chromosome and accumulate around the transcriptional start sites of the known genes. Thus, the occurrence of Z-DNA across human genomic sequences mirrors that of a known eukaryotic transcription factor. In addition, 43 of the 383 fully annotated chromosomal genes have ZDRs within 2 nucleosomes upstream of strong NFIs. This suggests a distinct class of human genes that may potentially be transcriptionally regulated by a mechanism …


Mono- And Disubstitutions Of (Hepta-2,5-Diyne-1,7-Diol) Bis(Dicobalt) Derivatives - Selectivity In Nicholas Reactions, Richard Guo, Romelo Gibe, James R. Green Jan 2004

Mono- And Disubstitutions Of (Hepta-2,5-Diyne-1,7-Diol) Bis(Dicobalt) Derivatives - Selectivity In Nicholas Reactions, Richard Guo, Romelo Gibe, James R. Green

Chemistry and Biochemistry Publications

Bis(hexacarbonyldicobalt) complexes of benzyl ether - methyl ether or benzyl ether - acetate derivatives of hepta-2,5-diyne-1,7-diols undergo selective Lewis-acid-mediated Nicholas reactions with enol silanes, silyl ketene acetals, and allylstannanes, preferentially replacing the methyl ether or acetate function. Hydride nucleophiles are similarly incorporated selectively using a benzyl ether - alcohol derivative. Subsequent Nicholas reaction at the benzyloxy-bearing site may be accomplished with an identical or a different nucleophile, affording skipped 1,4-diyne-Co-4(CO)(12) complexes. In instances of lower selectivity for monosubstitution reactions with benzyl ethers, reverting to the use of a menthyl ether - methyl ether complex gives much improved selectivity for methyl …


Optimization Of Conditions For Studies Of Protein Unfolding By Hydrogen Exchange/Mass Spectrometry, A.S. Raza, David L. Smith Jan 2004

Optimization Of Conditions For Studies Of Protein Unfolding By Hydrogen Exchange/Mass Spectrometry, A.S. Raza, David L. Smith

Chemistry Department: Faculty Publications

Understanding the forces driving protein folding and aggregation is an essential step in developing means for controlling these important processes. Amide hydrogen exchange, coupled with mass spectrometry, has become an important method for studying protein unfolding and refolding. To extend procedures developed to study unfolding of relatively soluble proteins to less soluble, aggregation-prone proteins requires special considerations. This publication describes a general strategy developed using yeast transaldolase, which aggregates easily under conditions required to study its unfolding. Results presented here show that reducing the protein concentration to the nanomolar range is essential for managing aggregation of transaldolase. In addition, the …


"A New Phase Of The Complex Trinitratotris(Triphenylphosphineoxide)Neodymium(Lll), J. Brannon Gary Jan 2004

"A New Phase Of The Complex Trinitratotris(Triphenylphosphineoxide)Neodymium(Lll), J. Brannon Gary

Faculty Publications

There has been considerable interest in the complexes formed by the lanthanides with various monodentate neutral ligands with O as the donor atom. Phosphine oxides, in particular, have proven useful in complexing to lanthanide metal ions and have found practical application in the solvent extraction and separation of lanthanides.1 Several lanthanide(III) nitrate complexes with triphenylphosphine oxide (OPPh3) have been prepared resulting in complexes having as few as two and as many as four OPPh3 groups per lanthanide center.2−4 An earlier study by Cousins and Hart5 identified the complex [Nd(OPPh3)3(NO3)3]. Two crystal phases of this same complex were briefly reported later …


Effect Of Different Thyroid States On Mitochondrial Porin Synthesis And Hexokinase Activity In Developing Rabbit Brain., Philadelphia University Jan 2004

Effect Of Different Thyroid States On Mitochondrial Porin Synthesis And Hexokinase Activity In Developing Rabbit Brain., Philadelphia University

Philadelphia University, Jordan

No abstract provided.


Coherent Vibrational Oscillation In Gold Prismatic Monolayer Periodic Nanoparticle Arrays, Wenyu Huang, Wei Qian, Mostafa A. El-Sayed Jan 2004

Coherent Vibrational Oscillation In Gold Prismatic Monolayer Periodic Nanoparticle Arrays, Wenyu Huang, Wei Qian, Mostafa A. El-Sayed

Wenyu Huang

We studied the ultrafast laser-induced coherent phonon oscillation in prismatic shaped gold nanoparticles assembled in monolayer periodic arrays by using the nanosphere lithographic technique. The amplitude and phase of the oscillation observed by ultrafast pump−probe transient spectroscopy is monitored as the wavelength of the dipolar surface plasmon absorption decreases. At a certain wavelength, the oscillation could not be observed. As the monitoring wavelength decreases further, the sign of the amplitude changes. From the wavelength at which the oscillation is not detected, the dependence of the absorption maxima on the size of the nanoparticles, the changes in the nanoparticle size are …


Photochemical Generation Of Nitrenium Ions From Protonated 1,1-Diarylhydrazines, Arthur Winter, Selina I. Thomas, Andrew C. Kung, Daniel E. Falvey Jan 2004

Photochemical Generation Of Nitrenium Ions From Protonated 1,1-Diarylhydrazines, Arthur Winter, Selina I. Thomas, Andrew C. Kung, Daniel E. Falvey

Arthur Winter

Laser flash photolysis experiments, chemical trapping studies, and time-dependent density functional theory calculations demonstrate that photolysis of protonated 1,1-diarylhydrazines generates N,N-diarylnitrenium ions.


Effect Of Meta Electron-Donating Groups On The Electronic Structure Of Substituted Phenyl Nitrenium Ions, Arthur Winter Jan 2004

Effect Of Meta Electron-Donating Groups On The Electronic Structure Of Substituted Phenyl Nitrenium Ions, Arthur Winter

Arthur Winter

Density functional theory (UB3LYP/6-31G(d,p)) was used to determine substituent effects on the singlet−triplet-state energy gap for 21 meta-substituted phenylnitrenium ions. It was found that strongly electron-donating substituents stabilize the triplet state relative to the singlet state. With sufficiently strong meta electron donors (e.g., m,m‘-diaminophenylnitrenium ion) the triplet is predicted to be the ground state. Analysis of equilibrium geometries, Kohn−Sham orbital distributions, and Mulliken spin densities for the triplet states of this series of nitrenium ions leads to the conclusion that there are two spatially distinct types of low-energy triplet states. Simple arylnitrenium ions such as phenylnitrenium ions as well as …


2,2':6',2"-Terpyridine N,N',N"-Trioxide, Kraig A. Wheeler, Scott E. Mckay, Silas C. Blackstock Jan 2004

2,2':6',2"-Terpyridine N,N',N"-Trioxide, Kraig A. Wheeler, Scott E. Mckay, Silas C. Blackstock

Kraig A. Wheeler

No abstract provided.


8th Bratislava International Conference On Modified Polymers: Modpol2003, Otto Vogl, Maria Omastova Jan 2004

8th Bratislava International Conference On Modified Polymers: Modpol2003, Otto Vogl, Maria Omastova

Otto Vogl

No abstract provided.


A. Cover Page, Title Page, Table Of Contents, And Forward, Otto Vogl Jan 2004

A. Cover Page, Title Page, Table Of Contents, And Forward, Otto Vogl

Otto Vogl

The History of the Pacific Polymer Federation (PPF) describes the background and pursuit that was needed to create the PPF and bring it to a functioning organization. It includes a general description, as well as edited Pacific Polymer Newsletters and articles that have been written in Polymer News describing additional PPF activities and the Pacific Polymer Conferences.


D. Founding Of The Pacific Polymer Federation, Otto Vogl Jan 2004

D. Founding Of The Pacific Polymer Federation, Otto Vogl

Otto Vogl

An account of the process which led to the founding of the Pacific Polymer Federation and a copy of the Constitution of the Pacific Polymer Federation.


E. President Of The Pacific Polymer Federation, Otto Vogl Jan 2004

E. President Of The Pacific Polymer Federation, Otto Vogl

Otto Vogl

A history of the first president of the Pacific Polymer Federation.


H. Pacific Polymer Federation Conference Reports, Otto Vogl Jan 2004

H. Pacific Polymer Federation Conference Reports, Otto Vogl

Otto Vogl

Reports of the first through the sixth Pacific Polymer Federation Conferences, held biennially 1989-1999. Also includes reporting on the Pacific Polymer Federation.


G. Excerpts Of Pacific Polymer Federation Newsletters, Otto Vogl Jan 2004

G. Excerpts Of Pacific Polymer Federation Newsletters, Otto Vogl

Otto Vogl

Excerpts of Pacific Polymer Federation Newsletters 1-13, 1989-2003. Covers the presidencies of Otto Vogl, Takeo Saegusa, Joseph Salamone, Chung Yup Kim, Fosong Wang, Takeshi Ogawa, and Supawan Tantayanon.


F. Growth Of The Pacific Polymer Federation, Otto Vogl Jan 2004

F. Growth Of The Pacific Polymer Federation, Otto Vogl

Otto Vogl

Describes the growth and development of the Pacific Polymer Federation,


B. The Signing Of The Constitution Of The Pacific Polymer Federation, Otto Vogl Jan 2004

B. The Signing Of The Constitution Of The Pacific Polymer Federation, Otto Vogl

Otto Vogl

The Constitution of the Pacific Polymer Federation was signed on October 19, 1987 in Tokyo, Japan at the Inter-national House in Roppongi, Tokyo by the Chairman of the ACS Division of Polymer Chemistry, S, R. Eby, and the Chair-man of the Foreign Affairs Committee, O. Vogl; by the President of the Society of Polymer Science Japan, M. Takayanagi; Chairman and Vice President for International Affairs, A. Abe. For the Polymer Division of the Royal Aus-tralian Institute of Chemistry, Chairman D.J.T. Hill and Chair-man of the International Committee, J.H. O'Donnell signed the Constitution.


C. Pacific Polymer Federation Presidents, Otto Vogl Jan 2004

C. Pacific Polymer Federation Presidents, Otto Vogl

Otto Vogl

Names and photographs of the presidents of the Pacific Polymer Federation.


Characterization Of Drawn And Undrawn Poly-L-Lactide Films By Differential Scanning Calorimetry, John F. Turner Ii, A. Riga, Anne O'Connor, Jing Zhang, Jennifer Collis Jan 2004

Characterization Of Drawn And Undrawn Poly-L-Lactide Films By Differential Scanning Calorimetry, John F. Turner Ii, A. Riga, Anne O'Connor, Jing Zhang, Jennifer Collis

Chemistry Faculty Publications

Poly-L-lactic acid (PLLA) is an optically active, biocompatible and biodegradable polymer that has been widely investigated as an artificial cell scaffold material. In its most crystalline form, PLLA is highly anisotropic and is one of the most piezoelectric polymers known. Conversely, amorphous PLLA exhibits little, if any, piezoelectric behavior. Compression molded PLLA films can be endowed with varying amounts of crystalline character and piezoelectricity by uniaxially stretching the polymer in a hot air bath. Understanding the precise crystalline architecture of PLLA that results from tensile drawing is important for constructing cell scaffolds that have highly tailored biodegradation and cell guiding …


Determination Of Crystalline Content Gradients In Cold-Drawn Poly-L-Lactic Acid Films By Dsc, Anne O'Connor, A. Riga, John F. Turner Ii Jan 2004

Determination Of Crystalline Content Gradients In Cold-Drawn Poly-L-Lactic Acid Films By Dsc, Anne O'Connor, A. Riga, John F. Turner Ii

Chemistry Faculty Publications

Poly-L-lactic acid (PLLA) is a semi-crystalline, optically active, biodegradable, and biocompatible polymer that has been utilized extensively in biomedical applications as an implantable artificial cell scaffold material. In its crystalline form, PLLA is piezoelectric and it has been implicated in the enhancement of electromechanically induced osteogenesis in vivo. In its amorphous state, however, PLLA does not exhibit piezoelectricity. By uniaxially cold-drawing the polymer, PLLA can be endowed with varying degrees of piezoelectricity. It is important to understand the crystalline architecture of drawn PLLA so that the osteogenic potential imparted by piezoelectricity, if any, can be differentiated from the effects of …


Determination Of Calories In Food Via Adiabatic Bomb Calorimeter, Kenneth C. Mcgill, Michelle L. Yasechko, Wendy K. Nkari Jan 2004

Determination Of Calories In Food Via Adiabatic Bomb Calorimeter, Kenneth C. Mcgill, Michelle L. Yasechko, Wendy K. Nkari

The Corinthian

The adiabatic bomb calorimeter has been an effective tool in facilitating heat transfer between molecules via combustion reaction. Heat is released from the substance combusted and transferred into another, usually water. The heat transferred is measured and the enthalpy of combustion determined for the combusted material. One such classic experiment is the determination of combustion enthalpy of sucrose, obtaining the calorimeter constant with benzoic acid. The results of an adiabatic combustion experiment can be taken one step further to determine the combustion enthalpy in kcal/g by a simple conversion calculation. Since food nutrition labels report calories per grams of serving …


Lanthanide Spectroscopic Studies Of The Dinuclear And Mg(Ii)-Dependent Pvuii Restriction Endonuclease, Gilles Muller, L. M. Bowen, J. P. Riehl, C. M. Dupureur Jan 2004

Lanthanide Spectroscopic Studies Of The Dinuclear And Mg(Ii)-Dependent Pvuii Restriction Endonuclease, Gilles Muller, L. M. Bowen, J. P. Riehl, C. M. Dupureur

Faculty Publications, Chemistry

Type II restriction enzymes are homodimeric systems that bind four to eight base pair palindromic recognition sequences of DNA and catalyze metal ion-dependent phosphodiester cleavage. While Mg(II) is required for cleavage in these enzymes, in some systems Ca(II) promotes avid substrate binding and sequence discrimination. These properties make them useful model systems for understanding the roles of alkaline earth metal ions in nucleic acid processing. We have previously shown that two Ca(II) ions stimulate DNA binding by PvuII endonuclease and that the trivalent lanthanide ions Tb(III) and Eu(III) support subnanomolar DNA binding in this system. Here we capitalize on this …


Altered Phosphorylation Of [Beta]-Catenin In Glucocorticoid Treated 235-1 Rat Pituitary Tumor Cells, Susie K. Saunders Jan 2004

Altered Phosphorylation Of [Beta]-Catenin In Glucocorticoid Treated 235-1 Rat Pituitary Tumor Cells, Susie K. Saunders

Theses, Dissertations and Capstones

Beta-catenin is an essential cell adhesion and signaling protein, associated with high prolactin levels in rat pituitary tumor cells. It has been shown that phosphorylation affects the location and activity of b-catenin. Glycogen synthase kinase (GSK3-b) is a serine-threonine kinase that phosphorylates b-catenin on N-terminal residues, targeting it for proteasomal degradation. Studies have shown that C-terminal tyrosine phosphorylation decreases the association of b-catenin with cadherin. In 235-1 rat pituitary tumor cells, our lab has shown that the glucocorticoid analog dexamethasone (Dex) decreases the half- life of b-catenin while increasing the activity of GSK3-b. The current study was undertaken to examine …


Semi-Biosynthesis Of Dna Nanostructures, Aoune Barhoumi Jan 2004

Semi-Biosynthesis Of Dna Nanostructures, Aoune Barhoumi

Theses, Dissertations and Capstones

Nanotechnology refers to all technologies aiming to build objects, make measurements, and carry out processes on the nanometer length scale. In particular molecular nanotechnology exemplifies the so-called "bottom up" approach, which is briefly defined as the ability to build useful nanostructures with molecular precision, such as molecular machinery. Such capability for controlling matter at the molecular scale has always been the dream of scientists.

All living things are nanofoundries. Billions of years ago, nature perfectly provided all living things with the most accurate biological nanotechnology systems. Cellular internal dynamics, communicative resonance in protein conformational states, viruses as microreplicators, nanoscale life …


Ac Frequency Dependence Of Electroluminescent Zns Phosphor Panel Color, Farrah Shantell Boggess-Machado Jan 2004

Ac Frequency Dependence Of Electroluminescent Zns Phosphor Panel Color, Farrah Shantell Boggess-Machado

Theses, Dissertations and Capstones

In this study, electroluminescent panels manufactured by Meadow River Enterprises were used to study the AC frequency dependence of their color. A project was developed to acquire their emittance color at various frequencies. Three frequencies were selected for the investigation. Data, obtained by measuring the spectrum at a constant excitation frequency, were taken for each of the three standard frequencies: 200 Hz, 1500 Hz, and 20 kHz. In general the higher the frequency, the bluer the emittance color of the panel. The lower the frequency, the more green the panel became. An explanation for this phenomenon, the frequency dependence of …