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Articles 1651 - 1680 of 2158

Full-Text Articles in Physical Sciences and Mathematics

Conformational Energy Calculations On Valinomycin, Rachel J. Cohen Jun 1984

Conformational Energy Calculations On Valinomycin, Rachel J. Cohen

Honors Theses

The antibiotic action of the ionophore valinomycin is a result of its ability to preferentially bind potassium ions and transport them across cellular membranes. Complexation is solely due to the molecular structure of this cyclic depsipeptide. In solution, the molecule exists in different conformers depending upon solvent polarity. Exact knowledge as to the structure of valinomycin in the aqueous and lipid cellular layers is thus difficult to determine. Many spectral studies of valinomycin have been undertaken utilizing a variety of instrumental methods and conformations existing in different solvents have been proposed. We have performed energy minimization procedures on these structures. …

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The Microstructure Determination Of Poly(B-Pinene), Kevin G. Perrigno Jun 1984

The Microstructure Determination Of Poly(B-Pinene), Kevin G. Perrigno

Honors Theses

The microstructure of poly(B-pinene) was determined through analysis of pyrolysis products.

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Synthesis And Spectral Studies Of Amides Of 9-Anthroic Acid, Juliana Rodgers Jun 1984

Synthesis And Spectral Studies Of Amides Of 9-Anthroic Acid, Juliana Rodgers

Honors Theses

The fluorescence energy, shape of the fluorescence spectrum, and the fluorescence efficiency of 9-anthramide (9-CONH2) and N,N-diethyl-9-anthramide (9-CONEt2) have been investigated as a function of solvent. For the 9-CONH2, the Sl energy decreases and the fluorescence spectra become structureless at the polar and nonpolar extremes of the solvent scale. This unusual solvent-dependent fluorescence behavior for 9-CONH2 is explained by a significant geometry change subsequent to excitation, whereby the exocyclic group rotates about the anthracene rings. In contrast, 9-CONEt2 shows solvent-independent behavior. The Sl energy generally remains constant and the fluorescence spectra show well-defined vibrational structure in a wide variety of …

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Detection And Quantification Of Atmospheric Carbonyl Compounds, Peter Gerard Schulam Jun 1984

Detection And Quantification Of Atmospheric Carbonyl Compounds, Peter Gerard Schulam

Honors Theses

Ambient air aldehyde analysis was performed in Schenectady, NY. The Technique, as prescribed by Kuntz et. Al. (7), entailed the trapping of the volatile aldehydes as their 2,4-dinitrophenylhydrazone derivatives in an acetonitrile solution. The derivatives were then separated on a reversed phase HPLC column and detexted by UV absorption at 254 and 360 nm., simultaneously. The air in Schenectady was found to contain formaedehyde and acetaldehyde at concentrations which ranged from .70 to 30.5 ppb and below that of detection to 1.6 ppb, respectively. Formaldehyde's daily average in Schenectady was 7.6 ppb. The formaldehyde and acetaldehyde levels at Whiteface Mtn. …

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A New Method For The Quantitative Determination Of Radon-222 In Natural Waters, Charles Whitlow Jan 1984

A New Method For The Quantitative Determination Of Radon-222 In Natural Waters, Charles Whitlow

Honors Theses

Several studies in the past have shown radon to be present in many natural waters including mineral springs, hot springs, rivers, lakes, and rainwater. A compilation of tables of radon concentration in mineral and hot springs all over the world was published by Kuroda in 1953. Most of this radon comes from radium and uranium minerals which the springs flow over. The radon concentration in lakes is from two major souces [sic]. One source is dissolved radium and the other is the inflow of high radon concentration groundwaters [sic].

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The Products Of The Gas Phase Ozonolysis Of Tetramethylethylene, Anthony R. Deangelo Jun 1983

The Products Of The Gas Phase Ozonolysis Of Tetramethylethylene, Anthony R. Deangelo

Honors Theses

The products of the ozonolysis of tetramethylethylene (TME) in the gas phase was studied. Reactions were run at concentrations between 10 and 400ppm TME and lower concentrations of ozone. The reactions were run at room temperature and atmospheric pressure. Gaseous products were studies by gas chromatography, mass spectrometry and HPLC analysis, the latter using 2, 4-dinitrophenylhydrazine derivatives of carbonyl products. Ozone concentrations and the determination of possible peroxidic products was accomplished by measuring the absorbance of a buffered KI solution (352 nm) after reaction with a known volume of gas. The possibility of acetone/ ozone and TME/ peroxides reactions were …

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Fluorescence Quenching Of Peptidyl Tryptophan By External Quenchers, Richard Dennin Jun 1983

Fluorescence Quenching Of Peptidyl Tryptophan By External Quenchers, Richard Dennin

Honors Theses

Fluorescence quenching data have been collected on several small peptides (1-4) residues which contain tryptophan. These data have been analyzed by a variety of methods. The classical Stern-Volmer equation is utilized to obtain Stern-Volmer plots of fluorescence quenching data. Substantial upward curvature is observed in the Stern-Volmer plots of all the peptides studied. Data were also analyzed via the modified Stern-Volmer static quenching model. Although this model could explain the deviation from simple Stern-Volmer behavior found in SV plots, the parameters used by the model were often physically “unrealistic”: Therefore, another form of data analysis was used. The newly proposed …

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Sterically Hindered Esters: Mechanisms Of Saponification, Frederick F. Fenter Jun 1983

Sterically Hindered Esters: Mechanisms Of Saponification, Frederick F. Fenter

Honors Theses

This paper discusses the mechanisms of base catalyzed hydrolysis of the secondary-butyl ester of 2, 2-dimethyl-propanoic acid (secondary-butyl pivaloate). Kinetic studies were carried out at 53° and near neutral hydroxide ion concentrations, but due to the slow velocity of reaction, no conclusions concerning the order of the kinetics of hydrolysis could be drawn. Also discussed is a scheme for an experiment involving the utilization of 018 enriched water in the saponification reaction of secondary-butyl pivolate under similar conditions of pH and temperature. The purpose of this experiment is to determine the site of oxygen cleavage during the hydrolysis. The analysis …

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Determination Of Aldehydes And Ketones In The Gas Phase, Clyde A. Kelly Jun 1983

Determination Of Aldehydes And Ketones In The Gas Phase, Clyde A. Kelly

Honors Theses

A recently developed method for the quantitative detection of carbonyl compounds in ambient air was investigated, specifically in order to further standardize and improve the process. The method involves drawing a gas phase sample of carbonyl compounds through impingers containing a 2, 4-Dinitrophenylhydrazine solution is then injected directly into the hplc for separation on a reversed phase column and quantitative determination by UV absorption at 254 nm and 360 nm simultaneously. The critical feature of the method (based upon a standard analytical derivatization reaction) is the use of the acetonitrile solvent. This allows for direct injection of the sampling solution …

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Cationic Copolymerization Of Styrene And Beta-Pinene: The Effect Of Solvent On Monomer Reactivity Ratios, George Yusun Paik Jun 1983

Cationic Copolymerization Of Styrene And Beta-Pinene: The Effect Of Solvent On Monomer Reactivity Ratios, George Yusun Paik

Honors Theses

Copolymers of styrene and B- pinene were synthesized at 30 degrees Celcius in methylene dichloride, carbon tetrachloride, and nitrobenzene. NMR analysis was used to determine the mole percent of styrene and B-pinene in the copolymer. These data were used to calculate monomer reactivity ratios in the three different solvents. It was also found that the styrene reactivity ratio increased when solvents with low dielectric constants were used. The B-pinene reactivity ratio also increased as the dielectric constant of the solvent increased. Pyrolysis and gas chromatography indicated that copolymerization may not have occurred in nitrobenzene and carbon tetrachloride if the mole …

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Syntheses And Fluorescence Properties Of Sterically-Hindered Esters Of 9-Anthroic Acid, Richard Leslie Dubs Jun 1983

Syntheses And Fluorescence Properties Of Sterically-Hindered Esters Of 9-Anthroic Acid, Richard Leslie Dubs

Honors Theses

For over a decade, Professor Thomas C. Werner and his students have been studying the unusual florescence properties of methyl-9-anthroate. In the ground state of this ester, the carboxyl group lies perpendicular to the anthracene rings due to steric inhibition by the peri hydrogens. Werner has postulated that, upon excitation, the carboxyl group rotates to form a planar configuration with the anthracene rings, and that this rotation is the cause of the unusual spectral properties. In our work, we have attempted to prove or disprove this hypothesis. We have chosen to synthesize analogues of methyl-9-anthroate in which carboxyl group rotation …

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The Apple Ii, Daniel M. Laby Jun 1983

The Apple Ii, Daniel M. Laby

Honors Theses

The apple II+ microcomputer was interfaced to an Aminco-Morrow stopped-flow Apparatus. This interface package can be broken into two parts; the hardware, or electrical connections necessary to link the two instruments, and secondly, the software, or programs written to control the interface package. A circuit was constructed as part of the interface hardware. This circuit consisted of several operational amplifiers connected in such a way as to transform the output voltage of the stopped-flow into one acceptable by the Apple computer. The software for this interface package is extensive. Programs were written that allowed the user to initialize the correct …

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Flash Photolysis: The Technique And Its Application, Marabeth G. Soltis Jun 1982

Flash Photolysis: The Technique And Its Application, Marabeth G. Soltis

Honors Theses

The application of flash photolysis in photochemistry offers an effective means to directly investigate reactive intermediates. This powerful technique rapidly converts a high percentage of molecules in their ground electronic state to upper excited states. This enables the disappearance of the excited species to be observed and kinetic information concerning the rate law and rate constants to be measured. The purpose of our work is to investigate the kinetics of the rate of decay of triplet anthracene in dilute solutions and to obtain rate constants for this reaction. The reduced expression for the decay of triplet anthracene is written: -dT/ …

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The Gas Phase Ozonolysis Of Tetramethylethylene, Catherine A. Rusik Jun 1982

The Gas Phase Ozonolysis Of Tetramethylethylene, Catherine A. Rusik

Honors Theses

The gas phase reaction between ozone and olefins is thought to proceed via an oxy-peroxy biradical intermediate, which may undergo cleavage or a variety of hydrogen abstractions. The validity of this biradical mechanism is investigated in a study of the products and stoichiometry of the gas phase ozonolysis of tetramethylethylene. Various pathways in the ozonolysis mechanism for this olefin are compared thermochemically to assess the relative favorability of the reaction possibilities of the biradical intermediate. Experimentally, olefin-rich and ozone rich reaction conditions are studied in the concentration range 10-800 ppm, using gas chromatography. The concentration of ozone present is determined …

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Liquid Chromatographic Studies Of Polar Aromatic Compounds In Soil, Jonathan Stuart Green Jun 1982

Liquid Chromatographic Studies Of Polar Aromatic Compounds In Soil, Jonathan Stuart Green

Honors Theses

The purpose of this project is to identify a component or components in red pine tree soil which may be associated with fungus growth inhibition.

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Microcomputer Interfacing With Chemical Instrumentation, Joel R. Meyer Jun 1982

Microcomputer Interfacing With Chemical Instrumentation, Joel R. Meyer

Honors Theses

In this paper we discuss the interface of a liquid chromatograph with an· Apple II+ microcomputer, The system consists of a Varian 5000 High Performance Liquid Chromatograph (HPLC), a Tracor 970A variable wavelength absorption detector (VWD), an Apple II+ computer, and an interface unit which consists of an operational amplifier and a Mountain Computer A/D + D/A converter. The op. amp. modifies the output signal of the VWD (0 to +lV) to meet the input specifications of the A/D converter (-5V to +5V). This allows the conversion of the continuous analog signal from the VWD to a digital signal, which …

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A Spectrophotometric Study Of The Rate Of Formation Of Violet Peroxychromate In Aqueous Solution, Stephen N. Witt Jun 1981

A Spectrophotometric Study Of The Rate Of Formation Of Violet Peroxychromate In Aqueous Solution, Stephen N. Witt

Honors Theses

The rate of formation of violet peroxychromate in aqueous solution was monitored spectrophotometrically at 540 nm. The method of initial rates enabled us to determine the exponents, x, y, and z, in the rate law for the violet species.

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A Survey Of Detection Methods For Ovulation And A Proposed Method For Estrogen Determination, Maria Lanni Jun 1981

A Survey Of Detection Methods For Ovulation And A Proposed Method For Estrogen Determination, Maria Lanni

Honors Theses

A rapid, accurate method of determining the exact phase of a menstrual cycle at a given time is extremely important. This information is vital to doctors studying menstrual abnormalities and more importantly as an aid in conceptive and contraceptive decisions. Many methods based on changes in the body have been used to detect ovulation. These nonquantitative methods depend on the cyclical variations in basal boy temperature, physical and chemical properties of mucus and content of saliva. These changes are influenced by changing hormone levels. Specicially, estrogen levels rise several days prior to ovulation, therefore, methods for determining estrogen concentration in …

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Conformational And Fluorescence Studies Of Small Peptides Containing Tryptophan, Gary S. Bowitch Jun 1980

Conformational And Fluorescence Studies Of Small Peptides Containing Tryptophan, Gary S. Bowitch

Honors Theses

Double-exponential decay has been observed for tryptophan and tryptophan-containing dipeptides. The Stern-Volmer mechanism was used to detect such decay. Conformational energy calculations were undertaken to elucidate fluorescence properties of these peptides. Ionic strength effects were found, for the most part, to be unimportant in Stern-Volmer quenchng experiments.

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A Comparison Of The Solvent And Temperature Dependence Of The Fluorescence Quantum Yield Of Methyl-1-, Methyl-2-, And Methyl-9-Anthroate, David B. Lyon Jun 1980

A Comparison Of The Solvent And Temperature Dependence Of The Fluorescence Quantum Yield Of Methyl-1-, Methyl-2-, And Methyl-9-Anthroate, David B. Lyon

Honors Theses

Two flouescence parameters, the room temperature quantum yield and the activation energy for nonradiative decay, were studied for the three possible monosbstituted methyl esters of anthroic acid in a number of aprotic, nonaromatic solvents. For the 1 and 2 substituted esters, the quantum yield increased and went through a maximum with decreasing S1 energy. In contrast, for methyl-9-anthroate, a general monotonic decrease in quantum yield with decreasing S1 energy was found. We assume, that intersystem crossing is the only nonradiative decay process that competes with flourescence for the esters. Since we find that the esters show temperature dependent flourescence, intersystem …

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The Preparation And Kinetics Of The Sterically Hindered Gold (Iii) Complex, [Au(1,1,4 - Me3 Dien)Cl] (Pf6)2, James S. Jackowski Jun 1980

The Preparation And Kinetics Of The Sterically Hindered Gold (Iii) Complex, [Au(1,1,4 - Me3 Dien)Cl] (Pf6)2, James S. Jackowski

Honors Theses

The N-alkylated gold (III) complex has been synthesized. The rate constant for the monobromination reaction was determined to be 132 ι mole -1 dec -1. The implications of such a value relative to similar non N0alkylated and other N-alkylated complexes are discussed.

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A Study Of The Mechanism Of Ribonuclease-S Using Cndo/2 Electronic Structure Calculations, Michael Arato Jun 1980

A Study Of The Mechanism Of Ribonuclease-S Using Cndo/2 Electronic Structure Calculations, Michael Arato

Honors Theses

Bovine Pancreatic Ribonuclease-S hydrolzes RNA molecules in a two step mechanism: 1. transphosphorylation, and 2. hydrolysis. The mechanism of the enzyme is studied using a model substrate for RNA, 2-hydroxyethyl methyl phosphate union. Electronic structure calculations are done at the CNDO/2 level, using the CININ optimization routine to minimize geometries. Two possible reaction paths are plotted for each step of the reaction, with the lowest activation energy path assumed to be the one taken by RNA. CNDO/2 results, however, yield negative activation anaeroles, a physically impossible result.

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Co2 Laser-Induced Decomposition Of Freon 113, Jeffrey Joseph Rusik Jun 1979

Co2 Laser-Induced Decomposition Of Freon 113, Jeffrey Joseph Rusik

Honors Theses

Gasgeous freon 113, or CC12FCC1F2, was irradiated with a continous wave carbon dioxide infared laser. The rat of formation of CF2CC1F, a decomposition product, was monitored using an infared spectrometer. The initial rates or product formation were related to irradiation wavelength and power, and the laser induced reaction was related to pyrolysis decomposition. A computer program which calculates the temperatures in a laser beam is modified and applied to the irradiations performed. It is determined that bi- or triphotonic absorption is occuring and that the laser induced reactions are photocatalyzed. A reaction model is discussed which combines thermal excitation, multiphotonic …

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Ozonolysis Of Certain Alpha, Beta-Unsaturated Carbonyl Compounds, Alan Howard Wynn Jun 1979

Ozonolysis Of Certain Alpha, Beta-Unsaturated Carbonyl Compounds, Alan Howard Wynn

Honors Theses

One of the intermediates in the ozonolysis of alkynes is the α carbonyl carbonyl oxide. The Hull rearrangment mechanism suggests that the α carbonyl carbonyl oxide can then rearrange via a rotation and cuclization to an anhydride.

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Peroxidase And Senescence, Michael Jay Chaskes Jun 1979

Peroxidase And Senescence, Michael Jay Chaskes

Honors Theses

Kinetin and α, α1 - dipryridyl prevented the rapid decrease of chlorophyll content in oat leaf intact segments senescing in the dark.

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Synthesis Of Sterically Hindered Disasters, Richard A. Bankowitz Jun 1979

Synthesis Of Sterically Hindered Disasters, Richard A. Bankowitz

Honors Theses

This thesis examines the synthesis of two sterically hindered diesters, neopentyl glycol dipivaloate and ditert-butyl 2, 2-diethylmalonate. The implications of this hinderance for hydrolysis in basic medium are discussed. The neopentyl glycol diester of 2,2-dimethylpropanoic acid is prepared with little difficulty by reaction of the glycol with the acid chloride in the presence of pyridine. The process gives the desired ester in approximately 66% yield. The preparation of the ditert-butyl ester of diethylmalonic acid is also attempted by means of the acid chloride in the presence of pyridine. Preparation of the diethylmalonyl dichloride using acetonitrile as a solvent in most …

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Kinetic Study Of The Chelate Ligand Unwrapping Reactions Of Sterically Hindered Gold (Iii) Complexes, James W. Thackeray Jun 1979

Kinetic Study Of The Chelate Ligand Unwrapping Reactions Of Sterically Hindered Gold (Iii) Complexes, James W. Thackeray

Honors Theses

The complexes [Au(Et2dien_H)Br]PF6, [AU(Me4dien_H)Br]Pf6, and [Au(Et3dien_H)Br]PF6 have been sunthesized and a kinetic study of their conjugate acids performed. This paper centers on the direct replacement of the tridentate ligang on the complex by bromide ion.

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Preparation And Kinetics Of Chloro-1,4,7-Triethyldiethylenetriamine Gold (Iii), Paul Lawrence Sargent Jun 1979

Preparation And Kinetics Of Chloro-1,4,7-Triethyldiethylenetriamine Gold (Iii), Paul Lawrence Sargent

Honors Theses

The square-planar complex has been synthesized and its aqueous solution chemistry investigated. The rate of bromide substitution for chloride has been studied along with the rate of the chelate un-wrapping reaction for the bromo-complex. These results aer compared with work on previously studied gold complexes.

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Calculation Of Mono-Cyclic Molecular Structures Using Mindo/3, Peter Mark Felker Jun 1979

Calculation Of Mono-Cyclic Molecular Structures Using Mindo/3, Peter Mark Felker

Honors Theses

Molecular geometries of selected, small cyclic compounds were calculated using the semi-epirical, S.C.F. molecular orbital method MINDO/3. Calculated geometries are compared with experiemental values to determine MINDO/3's effectiveness. It is found that the method has several systematic deficiencies. In Particular, carbon-oxygen single bond distances are calculated to be too short.

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Study Of Cndo/2 For The Prediction Of Geometries Of Phosphorus-Containing Molecules, Mark A. Fraser Jun 1979

Study Of Cndo/2 For The Prediction Of Geometries Of Phosphorus-Containing Molecules, Mark A. Fraser

Honors Theses

The method of CNDO/2 is presently being used to study the mechanisms of hydrolysis of phosphate esters. The question, therefore, arises whether or not CNDO/2 can accurately predict the geometries of phosphorus containing molecules. Using an optimizer adapted from the method of Rosenbrock, 41 compounds were tested.

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