Browsing by Subject "Division of Science and Mathematics"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Fire as an Ecological Factor in Northeastern Minnesota
    (1974-08) Enley, Mary Ellen
    Research during the past four decades has shown that fire is a natural agent which has been shaping the composition and boundaries of forests and prairies long before the appearance of modern man in such areas. In America, Indians often set fires for purposes such as driving game, clearing forest underbrush and prairie farmland, obtaining firewood, signaling, controlling insects, and increasing the berry crop (Ahlgren and Ahlgren, 1960). Failure to recognize that ecosystems may be fireadapted has resulted in management practices that threaten the balance of living organisms within such ecosystems. Odum (1971) includes fire as an important limiting factor along with other agents such as water, light, moisture, and air. Two extreme types of forest fires are crown fires and surface fires. The former often destroys all vegetation and may consume humus so as to expose mineral soil. Surface fires can move through groves of mature trees without noticeably damaging them, eliminating some components of the understory and creating favorable conditions for the development of others. Light surface fires often reduce the flammability of the forests, speeding the decay process, and creating a seedbed favorable for the reseeding of species requiring lesser humus accumulation. Scientists and the public have regarded fire as a destructive, wholly negative event which is to be avoided at all costs. Reversing such prejudices has generally progressed well enough among scientists, and the relatively young area of study known as fire ecology now has many disciples. Recent events in certain National Parks suggest that the public, given the facts and concepts, is willing to accept the current views regarding the importance of fire. The first project to include the use of wildfire as a management tool on National Forest lands was initiated in 1972 for a portion of the Selway-Bitterroot Wilderness (SBW) of northern Idaho and western Montana (Aldrich and Mutch, 1972). Under this policy, fire control is brought into operation when fires threaten to cross the boundary of the study area and when fire danger rating is high. Extensive investigations in plant ecology indicate that the vegetational composition of the SBW is showing characteristics which threaten the continued existence of the highly diversified vegetation of this region, due to the fire control policies effective since the 1930's (Habeck, 1972). The purpose of this paper is to investigate the nature of the role of fire in northeastern Minnesota, regarding its influence primarily on vegetation. Paleobotanical research in the Boundary Waters Canoe Area (BWCA) and study of vegetational characteristics provide a history of fire and plant cover for certain areas of northeastern Minnesota.
  • Thumbnail Image
    Item
    PBC-DFT : An Efficient Method to Calculate Energy Band Gaps of Conducting Polymers used in Solar Cells
    (2010) Schmidt, Jennifer A.; Koehn, Ryan E.; Pappenfus, Ted M.; Alia, Joseph D.
    In recent years, conducting polymers have gained attention for their promising application in solar cells due to their potential low cost, lightweight, and flexibility. Desirable polymers have a small band gap and a low HOMO energy level. Methods of finding this band gap exist using density functional theory (DFT) by calculating the energy gaps of increasing oligomer lengths (n), and plotting the HOMO-LUMO gap (in eV) as a function of the reciprocal polymer length (1/n). This method, however, proves time consuming and computationally costly. An alternative, less time-consuming method using periodic boundary conditions (PBC) exists. In our research, we studied existing donor-acceptor polymers from the literature and used PBC to calculate their band gaps for comparison with experimental data. To perform these calculations we used DFT at the B3LYP/3-21G(d) level of theory on optimized dimers. The PBC method yields results consistent with experimental values and can be useful in determining theoretical band gaps prior to synthesis which can aid in saving valuable lab time.
  • Thumbnail Image
    Item
    Renewable Energy and Sustainable Chemistry Across the Undergraduate Chemistry Curriculum
    (2010) Pappenfus, Ted M.; Carpenter, Nancy E.; Soderberg, Timothy J.; Power, Caleb; Koehn, Ryan E.; Schmidt, Jennifer
    Issues of energy and sustainability are having a direct impact on the public and are capturing the interests of many. As result, it is no surprise that science, including the field of chemistry, will become more connected with society in the future. To address this connection, we are in the process of integrating important elements of renewable energy and sustainable chemistry across the undergraduate chemistry curriculum at the University of Minnesota, Morris. This project strives to create a curriculum which is more interdisciplinary with respect to both teaching and research and which introduces topics that are timely, yet essential in preparing undergraduate students. Our initial efforts are focused on three key areas: (i) developing new courses in renewable energy and sustainability; (ii) integrating photovoltaics across the undergraduate curriculum; and (iii) illustrating the role of biochemistry in renewable energy and sustainability. Our goal is to develop a far-reaching energy and sustainable chemistry curriculum that complements the traditional curriculum and better prepares our future graduates for success in addressing global problems. An overview of the project will be presented along with our preliminary results.