Spectroelectrochemical Elucidation of the Kinetics of Two Closely Spaced Electron Transfers

The use of spectroelectrochemistry to facilitate the analysis of an EE mechanism was reported in this work. Using a set of spectra as a function of potential, the spectra of all three oxidation states were determined using evolving window factor analysis. From these spectra, the concentration of each species in solution was determined for each potential. Using these data, the current was calculated. Unlike the direct measurement of current, the current due to each redox process was determined, allowing one to analyze each redox process separate from the other. With the use of the Butler–Volmer equation, the redox potential and the heterogeneous electron transfer parameters were measured. The spectrally determined current has the advantage of determining the current due to each redox process which is not generally possible with voltammetric data when the redox potentials are close together. This method was applied to the spectroelectrochemical reduction of Escherichia coli sulfite reductase hemoprotein (SiR-HP) in a phosphate buffer and in the presence of cyanide. The electrochemical parameters (E°’s, k°’s and α’s) for each electron transfer were calculated for both the uncoordinated and cyanide coordinated species. The rates of electron transfer for the siroheme and iron–sulfur cluster were slower than the rates observed for other heme proteins. This is probably due to the fact that this protein is significantly larger than most of the heme protein previously studied. This approach is a powerful tool for two-electron transfers when the E° values are close together

Use of Evolutionary Factor Analysis in the Spectroelectrochemistry of Escherichia coli Sulfite Reductase Hemoprotein and a Mo/Fe/S Cluster

The deconvolution of spectroelectrochemical data is often quite difficult if the spectra of intermediates are not known. Factor analysis, however, has been shown to be a powerful technique which can make it possible to deconvolute overlapping spectra. In this work, evolving factor analysis will be used to determine the number of intermediates and the spectra of those species for two typical spectroelectrochemical experiments:  linear scan voltammetry and chronoabsorptometry in a thin-layer cell. The first system was the reduction of E. coli sulfite reductase hemoprotein (SiR-HP). Principal factor analysis indicated that three species were present. By using evolving factor analysis, the potential regions where each of the species were present were identified, and their concentrations and spectra were determined by the use of the mass balance equation. The spectra of the one-electron (SiR-HP1-) and two-electron (SiR-HP2-) reduced product were compared with previous work. The second experiment was the chronoabsorptometry of Cl2FeS2MoS2FeCl22- in methylene chloride. This experiment indicated that five species were present during the experiment. The entire set of 61 spectra were fit by assuming that there were 4 species present during the electrolysis. The rate constant for the appearance of subsequent species fit quite well with the rate constant for the disappearance of previous species. The spectra of the intermediates and final product were obtained using evolving factor analysis and a mass balance equation. Identification of the fifth species, which was probably the initial reduction product, Cl2FeS2MoS2FeCl23-, was difficult due to its low concentration and the fact that it was present in the same time region as the starting material

Use of Factor Analysis in Multi‐Electron Spectroelectrochemistry

Spectroelectrochemistry and voltammetry contain both unique and complementary information. For multielectron transfers, information on each electron exchange is only directly accessible in the voltammetric data if the potentials are well separated so that two distinct waves can be observed. If the E°’s are close together, the voltammetric data will contain the sum of the two exchanges which can only be deconvoluted by modeling the system and solving the appropriate equations. On the other hand, the spectroscopic data contains direct information on each electron exchange even when the E°’s are close together. Unfortunately, this information cannot be readily extracted if the intermediate oxidation state does not have a potential region where it is the dominant species. Chemometric methods such as factor analysis though can be used to deduce the spectra of each species even if they don’t dominate in any potential region. Initial work on the application of factor analysis to spectroelectrochemistry has been reported. Traditional methods of electroanalytical analysis are based on models that relate the concentration of electroactive materials to electrode potentials and solution concentrations. The model and parameters are adjusted to obtain the best fit to a model. Chemometric methods such as factor analysis allow the experimenter to determine solution concentrations without knowledge of the precise electrochemical mechanism. The utility of this approach will be demonstrated by the study of a protein, E. coli sulfite reductase hemoprotein, which is capable of transferring two-electrons and the ΔE° values are less than 100 mV, causing the waves to overlap. With these methods more detailed information on the electron transfer rate and associated kinetics processes can be more clearly identified

Evaluation of a University-Community Partnership to Provide Home-Based, Mental Health Services for Children from Families Living in Poverty

A university-community partnership is described that resulted in the development of community-based mental health services for young children from families living in poverty. The purpose of this pilot project was to implement an evidence-based treatment program in the homes of an at-risk population of children with significant emotional and behavior problems that were further complicated by developmental delays. Outcomes for 237 children who participated in the clinic’s treatment program over a 2 year period are presented. Comparisons are included between treatment completers and non-completers and the issues of subject attrition, potential subject selection bias, and the generalizability of the results are addressed. The need for more professionals who are trained to address mental health issues in very young children who live in very challenging conditions are discussed

Texas Business Review, January 1976

The Business Situation in Texas; The Last Hundred Years; The Next Hundred Years; Electric Funds Transference: Development and Prospects; Texas Construction: Four Decades of ChangeBureau of Business Researc

The Transformative Power of Engaging in Urban Greening Projects

Community greening efforts can improve urban ecological health, but what impacts do they have upon local residents’ environmental attitudes and actions. Research suggests that the success of urban tree planting and other improvements require the stewardship of local residents, particularly in the face of dwindling public investment in green spaces. This study looks at the notion that participation in urban greening projects may have as much to do with helping inner-city residents’ sense of community, connection to place, and empowerment, as improving ecological health. The study involved an evaluative survey of participants in environmental stewardship projects in Boston. This pilot study asked a range of items related to participants’ environmental knowledge and changes in their environmental attitudes and behaviors after volunteering. The study results found an increase in participants’ willingness to engage in environmentally beneficial behaviors in their own yard, including planting or maintaining street trees; as well as increased sense of community. In addition, participants in these community-centered urban greening projects, which included street tree planting and community gardens, expressed a greater willingness to take action to address other community issues. The study provides insights for those engaged in increasing valuable urban green space while at the same time interested in the broader issues facing inner-city neighborhoods

Syllabus: Sustainable Green Infrastructure Planning and Design

Green infrastructure planning requires a systems approach to improving ecological function while providing vital ecosystem services for human populations. This course will introduce students to the concepts, theories, and applications of greenway and green infrastructure planning at multiple scales, including the site-level, neighborhood, and regional scales. A particular area of focus will be the relationship of green infrastructure for improving hydrology and riparian corridors as part of comprehensive green space planning for recreation and cultural resources. The course will look at a wide range of systems including water, transportation, and food systems. A case study approach will be used to study green infrastructure projects both domestically and internationally from a planning and policy perspective, as well as implementation

Exploring Preferences for Urban Greening in Association with Learning About Sustainability in a Museum-based Urban Ecology Exhibit

Sustainable urban design and planning is grounded in understanding complex interconnecting relationships between human and ecological processes (Alberti & Marzluff, 2004). While compulsory education may provide an introduction to this subject, supplementary means are necessary in order to support citizen knowledge, interest and understanding of these complex relationships. Informal learning settings, such as museums, create opportunities for lifelong learning (Falk and Dierking, 2010) and can introduce, incorporate and link urban sustainability issues to provide an accessible and engaging introduction to the subject. Sustainable responses to urban development point to the need for higher density neighbourhoods coupled with extensive urban tree canopy (Alberti & Marzluff, 2004). However, more research is needed to ascertain if these urban forms match the preferred settings of urban residents. A family science museum provides a unique setting to explore urban greening in residential settings and provides museum visitors with the opportunity to participate in social-science research

Building Connections to the Minute Man National Historic Park: Greenway Planning and Cultural Landscape Design

The Minute Man National Historic Park (NHP) in Massachusetts commemorates the Battle of Lexington and Concord (1775) that began the American Revolution. The National Park created in 1959 seeks to interpret the battle and restore the agricultural landscapes of the revolutionary period. The Park is situated within the larger Freedom’s Way National Heritage Area (FWNHA) that was designated in 2009 to preserve the extensive historic cultural resources of the region, including such gems as Thoreau’s Walden Pond. Unfortunately, the Minute Man NHP is divided into four units and bisected by a busy state highway that makes wayfinding challenging for visitors. Moreover, the National Trust for Historic Preservation listed the Minute Man NHP “as one of America’s most endangered Places” (NTHP, 2003) due to the impacts of surrounding traffic, noise, and incompatible developments. There are several existing and proposed projects including the Battle Road Trail, Minute Man Bike Trail and Scenic Byway that have the potential to link the Park’s resources, but key connections are missing to create a coherent network. To address these challenges, this project, a partnership between the US National Park Service, FWNHA, and the University of Massachusetts, Amherst uses greenways as an organizing element to improve pedestrian and bike connections from the Park to the many nearby historic, cultural, and recreation resources, while providing visitors an alternative to touring the park by car. An undergraduate landscape architecture studio under the direction of the authors developed a greenway plan for the surrounding area with regional connections, as well as designed key sites and corridors along this greenway network that act as gateways and nodes for cultural and historical interpretation. This project exemplifies the challenges of historic and cultural planning within a developed suburban setting where local and regional recreation demands put pressure on historic landscapes. In addition, the fact that several key sites are outside the jurisdiction of the National Park in municipal, non-profit, or private ownership exemplifies the need for collaborative planning efforts. Finally, the project shows the management issues that continue after designation of historic corridors