Hunsicker D.M.,Northland College |
Dauphinais B.C.,Northland College |
Mc Ilrath S.P.,Northland College |
Robertson N.J.,Northland College
Macromolecular Rapid Communications | Year: 2012
The Milstein catalyst has proven to be highly effective for the conversion of alcohols to esters, as well as alcohols and amines to amides and polyamides. We have recently found that the catalyst's range can be extended to very efficient in vacuo dehydrogenation polymerization of αω-diols to generate polyesters. The gaseous hydrogen byproduct that is produced is easily removed to drive the equilibrium toward product, which leads to the formation of high molecular weight polymer (̄M n up to 145 000 g mol -1). This optimized methodology works well to polymerize diols with a spacer of six carbons or more. Diols with fewer carbons are cyclized to lactone; the dividing point is the dehydrogenation of 1,5-pentanediol, which leads to a mixture of polyester and lactone. Reported herein is the synthesis and characterization of five aliphatic polyesters prepared via this novel dehydrogenation polymerization approach. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Johnson S.E.,University of Wisconsin - Madison |
Johnson S.E.,Northland College |
Waller D.M.,University of Wisconsin - Madison
Canadian Journal of Forest Research | Year: 2013
Floodplain and swamp forests are undergoing extensive changes due to altered flow regimes, invasive species, logging, and various land use changes. These changes often go unnoticed due to the absence of adequate baseline data and monitoring. Using a data set from 55 years ago, we resampled 50 lowland forest stands in southern Wisconsin to assess changes in forest overstory composition, structure, diversity, and dominant species abundances. We also applied univariate and multivariate analyses to determine whether these changes varied between dam-regulated and unregulated rivers, tree species with different flooding tolerances, the presence of logging, and variations in edaphic and hydrologic variables. Although these forests display various types of resilience, their forest canopies are substantially different from 55 years ago, reflecting shifts in hydrology and the impacts of disease. On average, these forests have retained the same local (alpha) diversity but have converged in species composition (declined in beta diversity). They are now composed of more and smaller trees. Along the unregulated rivers, colonizing species have declined while later successional flood-tolerant species have increased. In the aftermath of Dutch elm disease, Ulmus spp. have greatly declined in abundance and size. Species with less flooding tolerance have generally increased across sites, especially along dam-regulated rivers. Because they are subject to chronic disturbances that reset succession, floodplain forests may respond more readily to shifts in disturbances regimes. Such forests may therefore serve as sentinels for forecasting the types of change that we can expect to unfold more gradually in upland forests.
Smith D.K.,Northland College
PLoS ONE | Year: 2015
Therizinosaurs represent a highly unusual clade of herbivorous theropods from the Cretaceous of North America and Asia. Following descriptions of the basicrania of the North American therizinosaurs Falcarius utahenisis and Nothronychus mckinleyi, the craniocervical musculature in both taxa is reconstructed using Tyrannosaurus, Allosaurus, and some extant birds as models. These muscles are subdivided into functional groups as dorsiflexors, lateroflexors, and ventroflexors. Lateroflexors and dorsiflexors in Nothronychus, but not Falcarius , are reduced, from the plesiomorphic theropod condition, but are still well developed. Attachments in both genera are favorable for an increase in ventroflexion in feeding, convergent with Allosaurus fragilis. Falcarius and Nothronychus are both characterized by a flat occipital condyle, followed by centra with shallow articular facets suggesting neck function very similar to that of an ostrich Struthio camelus. Neck movement was a combined result of minimal movement between the individual cervical vertebrae. © 2015 David K. Smith.
Garcia-Berthou E.,University of Girona |
Carmona-Catot G.,University of Girona |
Merciai R.,University of Girona |
Ogle D.H.,Northland College
Reviews in Fish Biology and Fisheries | Year: 2012
The growth of many organisms is seasonal, with a dependence on variation in temperature, light, and food availability. A growth model proposed by Somers (Fishbyte 6:8-11, 1988) is one of the most widely used models to describe seasonal growth. We point out that three different formulae (beyond numerous typographical errors) have been used in the literature referring to Somers (Fishbyte 6:8-11, 1988). These formulae correspond to different curves and yield different parameter estimates with different biological interpretations. These inconsistencies have led to the wrong identification of the period of lowest growth rate (winter point) in some papers of the literature. We urge authors to carefully edit their formulae to assure use of the original definition in Somers (Fishbyte 6:8-11, 1988). © 2012 Springer Science+Business Media B.V.
Johnson S.E.,Northland College |
Mudrak E.L.,Iowa State University |
Waller D.M.,University of Wisconsin - Madison
Journal of Vegetation Science | Year: 2014
Questions: Changes in land use, altered flow regimes, invasions by pests and pathogens, and climate change are, separately and together, altering ecological dynamics of floodplain forests. The complex changes these forces impose often go unnoticed due to a lack of reliable baseline data. Using historical data from the 1950s and re-survey data on floodplain forest understories, we ask: (1) what is the direction, magnitude and nature of changes in local and regional diversity; (2) have these floodplain communities become more homogenous in composition due to losses of native species and increases in non-natives; (3) has the relationship between the ground layer and overstorey community weakened over time; and (4) are changes in local and regional diversity among these floodplain forests more or less pronounced than in nearby upland forests? Location: Floodplain forests throughout southern Wisconsin, USA. Methods: We quantified composition of vegetation in the understorey and overstorey of 40 sites and compared these data with data from the 1950s using a combination of uni- and multivariate analyses. We focus on changes in local vs regional diversity. Results: Although average site-level diversity has increased by 18.5%, sites are now 30% more similar to each other, reflecting a pronounced decline in among-site (beta) diversity. Although exotic species have increased in site occupancy and abundance, increases in native woody plants (+30%), graminoids (+24%) and forbs (+16%) drive most of these changes in local and regional diversity. Sites have experienced an average species turnover rate of 39% since the 1950s, and understories are now 39% more correlated with canopy composition than in the 1950s. Biotic homogenization among these floodplain forests since the 1950s is 23.3% higher than the increase in similarity observed in nearby upland forests. Conclusions: Vegetation changes in floodplain understories differ from changes previously documented in nearby upland forests. Floodplain forests have experienced a faster rate of biotic homogenization. Unlike upland forests the homogenization trend in these floodplain forests is accompanied by increases in site-level diversity. These may reflect widespread colonization by certain native species. Both trends may also reflect relatively high connectivity among floodplain forests and control of hydrologic fluctuations via dams. © 2013 International Association for Vegetation Science.
Courtwright J.,Northland College |
Courtwright J.,James Madison University |
Findlay S.E.G.,Cary Institute of Ecosystem Studies
Wetlands | Year: 2011
Hudson River freshwater tidal swamps have dynamic flooding and oxygenation regimes due to daily tidal flushing. Microtopography, small scale differences in elevation, adds even more complexity to inundation patterns and may have important implications for nutrient flow and wetland plant communities. The objective of this study was to determine if differences in inundation between microtopographic features were sufficient to alter physical, chemical, and biological attributes. Microtopography significantly affected flooding duration and redox conditions. Hummocks had lower concentrations of soluble phosphate in their porewater probably due to differing depths of iron oxidation. Hummocks also had lower porewater ammonium concentrations which could be explained by higher plant uptake of nitrogen on hummocks or less ammonium being nitrified and subsequently denitrified in hollows due to lack of oxygen. Decomposition rates were slower in hollows perhaps due to lack of oxygen due to flooding or differing decomposer communities. Fewer herbaceous plant species were found in hollows compared to hummocks perhaps because of hollow's anoxic soils. Microtopography affects freshwater tidal swamp ecosystem function by affecting oxygen penetration, nutrient availability, rates of decomposition, and herbaceous plant species distributions. © Society of Wetland Scientists 2011.
Rooney T.P.,Wright State University |
Leach M.K.,Northland College
American Midland Naturalist | Year: 2010
We examined changes in plant species composition at Faville Prairie in southeastern Wisconsin, based on surveys in permanently-marked, 2 × 2 m quadrats in 19461948, 19761978 and 2005. Permanent quadrats were distributed across a wide soil moisture gradient. During settlement the site was never cultivated but was mowed for hay for several decades prior to 1946, and burned most years during the dormant season after 1946. Total species richness increased 47 between 19461948 and 2005, while species density per quadrat doubled. Only nine non-native species were present in 2005 and most were uncommon. Species density of habitat generalists increased nearly fourfold; moderate specialists increased 43; and remnant specialists increased nearly twofold. Species density of endangered, threatened and special concern species (collectively conservation-dependent species) increased ninefold. Species density of C3 graminoids, C4 grasses, legumes, woody plants and forbs all increased through time. The majority of species density increases were attained by the 19761978 sampling period and remained high since. Elsewhere in Wisconsin, prairie habitat specialists have been declining. Our findings run counter to general trends throughout the state. It is likely that the change from annual mowing to annual prescribed burns accounts for the increases in species density. © 2010, American Midland Naturalist.
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 199.93K | Year: 2015
Unmanned aircraft systems (UAS) is the most rapidly growing sector of the aerospace industry fueled with continuous advancements in technology, and the Federal Aviation Administration is currently working on a plan to integrate UAS into the national airspace system (NAS) by 2015. This project at Northland Community and Technical College (NCTC) will bridge the gap between new and emerging aviation technology and technician education in the area of UAS and will increase career opportunities through the development of a pipeline for highly skilled workers to meet industry demands. A study released in 2013 by the Association for Unmanned Vehicle Systems International (AUVSI) forecast the economic impact of the integration of UAS into the NAS to total more than $13.6 billion in the first three years of integration and to grow sustainably for the foreseeable future, cumulating to more than $82.1 billion between 2015 and 2025. AUVSI also stated the integration into the NAS will create more than 70,000 new jobs in the first 3 years. By 2025, total job creation is estimated at 103,776 jobs. The project will initiate, facilitate, and maintain partnerships with industry leaders, 7-14 schools and higher education institutions to confirm workforce competencies and curriculum. It will increase educational opportunities to advance aviation technologies and the impacts regionally and nationally, helping to position the U.S. as a leader in the global UAS market. By collaborating with key stakeholders at the UAS test sites, the project will create models for technician education in UAS maintenance and meet technical employment needs of UAS and other high-growth industries. With the rapid growth in these new technologies there is a great opportunity to influence standardized education for this science, technology, engineering, and technology (STEM) discipline.
To address current skill gaps and educational opportunities, the project will create innovative, industry driven curriculum for UAS and related disciplines, industry recognized stackable credentials, and technician career pathways. It will provide professional development for faculty members to stay current in emerging technologies and learn new teaching methods that will allow them to incorporate these materials into UAS programs as well as in existing STEM courses. It will promote and provide educational opportunities to underrepresented populations and rural areas by leveraging tele-presence technology to expand geographical reach and serve non-traditional students. Project personnel will disseminate instructional materials, research information, and papers for use by educational and industry partners. Workshops and summer camps will promote awareness to secondary and post-secondary educators and students interested in STEM. A comprehensive evaluation will identify best practices in the education of UAS technicians to fill this emerging national need.
Agency: NSF | Branch: Standard Grant | Program: | Phase: Macromolec/Supramolec/Nano | Award Amount: 242.60K | Year: 2016
Plastics are made from polymers and polymer manufacture represents one of the largest and most dynamic sectors of the chemical industry. Companies are targeting better performing polymer materials derived from more economical and environmentally friendly (bio-renewable) feedstocks. These improvements are often driven by chemical advancements in polymer synthesis research, such as the work supported by this award. It is critical to the field of polymer chemistry to improve the basic understanding of the relationships between polymer structure and the properties of the resulting plastic, which is a primary goal of this research. Undergraduate students, including low income and first generation college students, perform laboratory work for this study and receive valuable training to prepare them for graduate school and/or employment in the chemical industry.
With the support from the Macromolecular, Supramolecular, and Nanochemistry Program of the NSF Division of Chemistry, Prof. Robertson of Northland College and Prof. Carney of the University of Wisconsin-Eau Claire conduct collaborative research to better understand the properties of ruthenium catalysts in polymerization reactions. Specifically, this project focuses on making advancements in five key areas: (1) preparation of polymers from bio-renewable monomers, such as 5-hydroxymethylfurfural (HMF), (2) polymer alternatives to polyurethanes (found in many paints, varnishes, adhesives, and foams), (3) increasing the utility of commodity plastics, (4) depolymerization methods to produce useful chemicals from waste plastics, and (5) synthesis of new ruthenium compounds to better understand the impacts of chemical structure on the catalysts performance. Toward this end, the research team is synthesizing and studying new ruthenium catalysts with structurally versatile N-phosphinoamidine and beta-diketimine ligand backbones.
Sonnier G.,University of Wisconsin - Madison |
Johnson S.E.,Northland College |
Amatangelo K.L.,New York University |
Rogers D.A.,University of Wisconsin - Parkside |
Waller D.M.,University of Wisconsin - Madison
Global Ecology and Biogeography | Year: 2014
Aim: Biotic homogenization - the tendency for communities to converge in species composition - has occurred in many ecosystems, creating management challenges. The extent to which this convergence in species composition is related to convergence in trait composition ('functional homogenization'), however, remains unresolved. Location: North America, Wisconsin. Methods: Using extensive plant community survey data from the 1950s and 2000s, and values for 11 traits measured on 169 species, we examined changes in functional beta diversity across 151 upland forest stands distributed across southern and northern Wisconsin. To estimate functional beta diversity, we used two recently developed pairwise functional dissimilarity metrics, plus an additive partitioning of functional diversity approach. Results: Using pairwise functional dissimilarity metrics, we found no significant changes in functional beta diversity through time in either southern or northern upland forests. Under additive partitioning, species alpha diversity was lower than species beta diversity; whereas functional alpha diversity was much higher than functional beta diversity in both time periods and across all forest types. This suggests a high turnover of species but a low turnover of traits among communities. Main conclusions: Although upland forests in Wisconsin have experienced taxonomic homogenization, they have not undergone functional homogenization, which may reflect a high functional redundancy among Wisconsin forest plants. As species decline further or disappear in response to habitat fragmentation and other global changes, functional redundancy may decline in a way that could diminish the functional diversity of Wisconsin's forests at both local and regional scales. © 2014 John Wiley & Sons Ltd.