Volume 3 Issue 3 December 2004

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https://doi.org/10.33697/ajur.2004.019

Guest Comment: The Drake University Conference on Undergraduate Research in the Sciences

https://doi.org/10.33697/ajur.2004.020

Author(s):

Heidi Sleister, Department of Biology, Charles Nelson, Department of Physics and Astronomy, Maria Bohorquez, Department of Chemistry

Affiliation:

Drake University, 2507 University Avenue, Des Moines, Iowa 50311-4505 USA


J-Aggregates of Cyanine Dyes in Aqueous Solution of Polymers: A Quantitative Study

https://doi.org/10.33697/ajur.2004.021

Author(s):

Wesley Tillmann and Hussein Samha

Affiliation:

Division of Chemistrym, Southern Utah University, 351 W. Center Street, SC 215 Cedar City, Utah 84720 USA

ABSTRACT:

The effect of polyvinylsulfate (PVS) on the spectroscopy of the cyanine dye, 1,1’-diethyl-2,2’-cyanine iodide (PIC), has been investigated using UV-vis spectroscopy. J-aggregates of the PIC dye were formed upon addition of PVS to the monomers of the dye in solution. The appearance of only one isosbestic point in the UV-vis spectra suggests that the dye monomers are quantitatively converted to J-aggregates and equilibrium was reached. Using Benisi-Hildebrand kinetics, aggregation number of 4 was calculated for the dye. In addition, a 1:2 mole ratio of PIC/PVS was calculated at the maximum capacity of the polymer.


Exactness, Tor and Flat Modules Over a Commutative Ring

https://doi.org/10.33697/ajur.2004.022

Author(s):

Abhishek Banerjee

Affiliation:

Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata 700108 INDIA

ABSTRACT:

In this paper, we principally explore flat modules over a commutative ring with identity. We do this in relation to projective and injective modules with the help of derived functors like Tor and Ext. We also consider an extension of the property of flatness and induce analogies with the “special cases” occurring in flat modules. We obtain some results on flatness in the context of a noetherian ring. We also characterize flat modules generated by one element and obtain a necessary condition for flatness of finitely generated modules.


Awareness, Partisanship and the Post-Convention Bounce: A Memory-Based Model of Post-Convention Presidential Candidate Evaluations Part 1—Introduction & Theoretical Analysis

https://doi.org/10.33697/ajur.2004.023

Author(s):

Justin Grimmer

Affiliation:

Department of Mathematics and Computer Science, Wabash College, Crawfordsville, Indiana 47933 USA

ABSTRACT:

This paper employs panel data to estimate the effects of awareness and political partisanship on post-convention candidate evaluations. The theoretical framework proposed by John Zaller (1992) is employed; however, a functional form that differs greatly from Zaller’s proposed model is derived from Zaller’s assumption and then estimated using standard OLS regression. I find that partisans of the opposite party were more resistant to the convention message of Bush than Gore, awareness plays a greater role in determining predicted post-convention change for Gore, and that Gore’s message was received and accepted at a higher rate than Bush’s message.


Thermal Desorption in Pure Hexane and Hexane/Butane Mixtures on Graphite

https://doi.org/10.33697/ajur.2004.024

Author(s):

Cary L. Pint

Affiliation:

Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614-0150 USA

ABSTRACT:

The results of an extensive study of desorption in hexane (monolayer and submonolayer) and hexane/butane mixtures initially adsorbed onto the graphite basal plane is presented. Molecular dynamics (MD) simulations are utilized to carry out atomistic simulations at temperatures 300≤T≤700 for all three cases studied. Results from submonolayer and monolayer hexane indicate that the desorption energy needed for the system to proceed with the desorption process is independent of the system’s coverage, which is in good agreement with experimental results. It is also found that simulations of desorption of hexane/butane mixtures yield a high ratio of butane molecules being desorbed from the surface at lower temperatures (300 K), suggesting a strong dependence of the desorption barrier upon alkane chain length. The results are discussed and compared to previous experimental and theoretical results.