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Achieving high yields in the large-scale agricultural systems that dominate the US landscape requires critical machine-enabled field operations to be executed in narrow windows of time. Novel cropping systems hold great promise to increase ecosystem services from these large-scale systems, but researchers and end-users need effective methods of representing the timing requirements of such systems. This gap prompted our exploration of approaches to visualize the timing of critical machine-enabled field operations. We refer to the resulting graphic as a field operations visualizer (FOV). We iterated multiple versions of the FOV through a user-centered process involving extensive stakeholder feedback. The resulting FOV version offers a straightforward method of visualizing operation sequences and identifying potential conflicts. Survey results suggest that the FOV provides significant operational insights to users about the timing challenges (or benefits) of novel cropping systems. The FOV may therefore be useful in guiding efforts to improve novel cropping systems and to thereby ultimately increase their deployment to deliver ecosystem services. [ABSTRACT FROM AUTHOR]

Perennial groundcover (PGC) has promise as a scalable approach to generating natural resource benefits and sustainable biofuel feedstock while preserving the high yields of annual row crop production. Partnering row crops with temporally and spatially complementary low-growing, shallow-rooted perennials, such as Kentucky bluegrass (KBG) (Poa pratensis L.), is one example of an emerging PGC system. PGC's ecosystem benefits can only be fully realized if commercial-scale adoption occurs, which hinges on its economic feasibility. This paper utilizes an enterprise budget framework to detail and compare the expected cost and revenue of establishing and maintaining PGC in row crop systems with standard continuous corn (SCC) (Zea mays L.) production, including stover harvest, but excluding economic incentives for ecosystem services. Optimistic and pessimistic assumptions were used, along with Monte Carlo simulation, to characterize the uncertainty in results. In the optimistic stover market scenario, Year 1 net returns for PGC averaged USD 84/ac less than for SCC; Year 2+ net returns averaged USD 83/ac more, meaning that cost parity with SCC occurs by the second PGC system year. Without stover revenue, parity is achieved after five years. These results affirm that PGC's economic viability is critically impacted by a groundcover's lifespan, the yield parity with SCC, and the availability of a stover market. [ABSTRACT FROM AUTHOR]

This column presents ideas and techniques to enhance science teaching. This month's issue describes preservice elementary teachers learning engineering principles from engineers. Few elementary teachers have experience with implementing engineering into the classroom. While engineering professional development opportunities for inservice teachers are becoming more numerous, engineering education is rarely required or even offered in elementary teacher-preparation programs. To prepare future elementary teachers to teach engineering, a collaborative partnership was formed between professors in Iowa State University's College of Engineering (CoE) and School of Education (SoE). The partnership included teacher education faculty in science and mathematics education and three engineering faculty who provided perspectives on content, knowledge, and skills foundational to engineering. Members of the partnership worked together to co-plan and co-implement engineering experiences across a teacher education program. These experiences included building engineering content knowledge through a Saturday short course, inclusion of engineering in methods courses, and a summer workshop that preceded a partnership with an engineering graduate student. This article describes the Saturday short course provided to prospective elementary teachers by three members of the engineering faculty and two from the teacher education faculty.

Summer research opportunities for undergraduates, such as those supported by the National Science Foundation's Research Experience for Undergraduates (REU) program, can be critical experiences that help persuade students to pursue research through graduate studies. Studies analyzing the key actions of successful mentors are scarce. The goal of this study was to explore how hypothesized "key actions" of mentors correlated with student perceptions of mentoring and of overall program quality, students' scholarly output resulting from the REU, and the influence of the REU on students' decisions to pursue graduate school. Students who participated in 11 REU programs at a large Midwestern US university in summer 2012 were surveyed in spring 2013 about their experiences in the program and with their primary research mentor. Results suggest that the key factors hypothesized to be associated with good mentoring correlated with students' ratings of their relationship with their mentor, students' overall program ratings, students' scholarly output resulting from the REU, and the influence of the REU on students' decisions to pursue graduate school. The six "key actions" hypothesized to be associated with good mentoring were significantly correlated with student experience in an REU program. Although none of the six actions is particularly complex, taking these actions is crucial and non-trivial. Prospective REU mentors could be informed about these key actions during mentor training activities. Future research could examine these six dimensions across postsecondary institutions and in mentoring relationships outside of REU programs.

Livestock in the state of Iowa, United States (US) produce over 50 × 106 Mg of wet-basis manure yearly. Biogas production from manure's anaerobic digestion (AD) can reduce greenhouse gas emissions, control odors, and provide renewable energy. Despite these benefits, AD is rarely deployed at swine farms in Iowa. In this work, we explore the economics of AD systems in Iowa to evaluate reasons for low deployment and explore the production cost impacts of biogas cleaning and injection into the natural gas grid, amending manure with biomass, and centralizing digesters across multiple farms. This work presents a static, spreadsheet-based technoeconomic model that embodies literature-based estimates of key system technical parameters, costs, and transportation fuel incentives and permits the examination of various scenarios. Key findings include that under the model assumptions, distributed, farm-scale digesters are not competitive with average natural gas prices in Iowa. A centralized production scenario can be competitive, provided that programs such as the low-carbon fuel standard (LCFS) and the renewable fuel standard (RFS) have sufficiently high credit values. [ABSTRACT FROM AUTHOR]

Abstract Background The availability and low cost of lignocellulosic biomass has caused tremendous interest in the bioconversion of this feedstock into liquid fuels. One measure of the economic viability of the bioconversion process is the ease with which a particular feedstock is hydrolyzed and fermented. Because monitoring the analytes in hydrolysis and fermentation experiments is time consuming, the objective of this study was to develop a rapid fluorescence-based method to monitor sugar production during biomass hydrolysis, and to demonstrate its application in monitoring corn stover hydrolysis. Results Hydrolytic enzymes were used in conjunction with Escherichia coli strain CA8404 (a hexose and pentose-consuming strain), modified to produce green fluorescent protein (GFP). The combination of hydrolytic enzymes and a sugar-consuming organism minimizes feedback inhibition of the hydrolytic enzymes. We observed that culture growth rate as measured by change in culture turbidity is proportional to GFP fluorescence and total growth and growth rate depends upon how much sugar is present at inoculation. Furthermore, it was possible to monitor the course of enzymatic hydrolysis in near real-time, though there are instrumentation challenges in doing this. Conclusion We found that instantaneous fluorescence is proportional to the bacterial growth rate. As growth rate is limited by the availability of sugar, the integral of fluorescence is proportional to the amount of sugar consumed by the microbe. We demonstrate that corn stover varieties can be differentiated based on sugar yields in enzymatic hydrolysis reactions using post-hydrolysis fluorescence measurements. Also, it may be possible to monitor fluorescence in real-time during hydrolysis to compare different hydrolysis protocols.

Many experiences in engineering education boast positive gains to students' learning and achievement. However, current literature is less clear on the economic costs associated with these efforts, or methods for performing said analyses. To address this gap, we proposed a structured approach to analyzing the incremental costs associated with an experience in engineering education. This method was modeled after those found in medicine and early childhood education. We illustrated our methodology using marginal (above baseline) time and cost ingredients that were collected during the development, pilot, and steady-state phases of a mechatronic experience in a first-year undergraduate engineering technology course. Specifically, our method included descriptive analysis, Pareto analysis, and cost per capacity estimate analysis, the latter of which has received limited discussion in current cost analysis literature. The purpose of our illustrated explanation was to provide a clear method for incremental cost analyses of experiences in engineering education. We found that the development, pilot, and steady-state phases cost just over $17.Ik (~S 12.4k for personnel and ~$4.7k for equipment), based on 2015 US$ and an enrollment capacity of 121 students. Cost vs. capacity scaled at a factor of - 0.64 (y = 3,121x-0.64, R² = 0.99), which was within the 95% interval for personnel and capital commonly observed in the chemical processing industry. Based on a four-year operational life and a range of 20-400 students per year, we estimated per seat total costs to range from roughly $70-5470, with our mechatronic experience averaging just under $150 per seat. Notably, the development phase cost, as well as the robot chassis and microcontroller capital cost were the primary cost terms of this intervention. [ABSTRACT FROM AUTHOR]

Abstract: The effect of batch thermosonication at 20 kHz on plasmin activity in skim milk, stored up to 49 days, was studied. The influence of sonication time was evaluated by heating samples to 72°C for 15 s, followed by sonication at 72 °C, at a constant amplitude of 170 µmpeak‐to‐peak (p–p) for 10, 30, or 60 s. The influence of temperature was evaluated by sonicating samples for 60 s at 15, 30, 45, 60 and 75°C at constant amplitude. Plasmin activity of treated as well as raw and heated control samples were analyzed on days 7, 21, 35, and 49. At all three times tested, thermosonication significantly decreased the plasmin activity compared to the raw and heated controls, with plasmin activity being reduced by over 90% after the 60 s treatment. Across the evaluated temperature range, samples that were thermosonicated displayed lower plasmin activity than their counterparts that were heated without sonication. Practical applications: In this study, batch thermosonication was explored as a means to reduce plasmin activity in skim milk. As protease activity can lead to adverse textural changes and off‐flavor development in milk, a reduction of plasmin activity is expected to enhance the quality of milk as a function of time. Results from this study suggest batch thermosonication can reduce plasmin activity, which indicates the potential of the method to extend the shelf life of skim milk. [ABSTRACT FROM AUTHOR]

In our review we examined the primary and secondary influences of mechatronic experiences on student engagement in fundamental engineering courses. Using a systematic review methodology, we collected 402 articles with publication dates ranging from 1990-2014. Screening on title and abstract information reduced our included sources to 137, from which we mapped six parent and 22 child codes. Appraising 17 of these articles we identified eight high quality studies as the focus of our synthesis, which identified five primary influences (Student Motivation, Self-Efficacy, Course Rigor, Learning Retention, and Gender) and two secondary influences (Accreditation and Ease-of-lmplementation). In these influences we found evidence that mechatronic experiences can increase student motivation, self-efficacy, and course rigor. Also, positive effects on learning retention, gender diversity, accreditation efforts, and ease of course content implementation were identified. Future research is needed to clarify: (1) if mechatronic experiences truly increase student motivation and self-efficacy more than lecture-based strategies, (2) how the positive short-term impacts of these experiences translate to subjective academic success (i.e., future course and career goals), (3) how implementation logistics are influenced by experience type (i.e., open-ended projects verse contests), class size, institution and industry support, etc., and (4) to what degree the factors of gender, underrepresented student groups, course curricular placement, and activity type influence student engagement. [ABSTRACT FROM AUTHOR]

Historical data from multiple institutions show that students who achieve a first-semester grade point average (GPA) below 2.0 are at substantially greater risk of leaving engineering programs before graduating with a degree than are those who achieved above 2.0. Identifying these “at risk” students prior to the start of their first semester could enable improved strategies to enhance their academic success and likelihood of graduation. This study used two distinct modeling approaches to predict first-term GPA group (low-risk: GPA ≥ 2.0; at-risk: GPA < 2.0) based upon data available prior to the student’s first pre-enrollment advising session. In the case of one of the approaches—which allowed a differential weighting of Type I to Type II errors—we explore how these weightings influences the prediction accuracy. The models used academic and demographic data for first-year engineering students from 2010 to 2012 from a single large public research-active institution. The two model types employed to build predictive models were (1) ordinary least squares multiple linear regression (MLR), and (2) classification and regression trees (CART). For both MLR and CART models, high school GPA and math placement exam scores were found to be significant predictors of first-term GPA. Increasing the cost of missing at-risk students in the CART models improves at-risk prediction accuracy but also increases the rate of false positives (incorrectly identifying a low-risk student as at-risk). The relative simplicity of the CART models, as well as the ease with which error-types can be weighted to reflect institutional values, encourages their use in this type of modeling effort. [ABSTRACT FROM AUTHOR]

A large number of students leave engineering majors prior to graduation despite efforts to increase retention rates. To improve retention rates in engineering programs, the reasons why students leave engineering must be determined. In this paper, we review the literature on attrition from engineering programs to identify the breadth of factors that contribute to students' decisions to leave. Fifty studies on student attrition from engineering programs were included in the primary part of this literature review. In the second half of the work, an additional twenty-five studies that focused on methods of increasing student retention, were examined. Six broad factors driving students to leave engineering were identified by examining the attrition literature: classroom and academic climate, grades and conceptual understanding, self-efficacy and self-confidence, high school preparation, interest and career goals, and race and gender. Evidence from the retention studies suggests that successful efforts to increase retention act on one or more of these factors. A clear gap in the literature is that of economics: the costs associated with losing students, and the costs associated with implementing retention strategies, are virtually unmentioned. [ABSTRACT FROM AUTHOR]

This paper describes a modeling effort demonstrating that dimensionless groupings of classical process parameters can be used to predicting process dynamics of batch simultaneous saccharification and fermentation (SSF) processes. Michaelis-Menten enzyme kinetics and Monod growth kinetics were employed, and inhibition of enzyme action and inhibition of microbial growth were neglected. The SSF process was characterized by the relative durations of three phases: A microbially-limited phase, a hydrolysis-limited phase, and a monosaccharide-depletion phase. The duration of these three phases were interrelated, and well predicted by the dimensionless magnitude of the monosaccharide peak (MSP). Thus, the MSP could be used as a single-value descriptor of an SSF process. The dimensionless ratio of the initial hydrolysis rate to the initial substrate consumption rate was shown to predict MSP, and an overall system time constant was shown to predict the total run time of a batch SSF process. [ABSTRACT FROM AUTHOR]

Naturally occurring estrogens in animal wastes may cause negative environmental impacts, yet their abundance in animal waste treatment and storage structures is poorly documented. To better quantify estrogen concentrations in animal wastes, multiple waste samples were collected from treatment and storage structures at dairy and swine facilities and analyzed for concentrations of 17β-estradiol (E2), estrone (E1), and 17α-estradiol by gas chromatography-mass spectroscopy and by enzyme linked immunosorbent assay (E2 only). Mass ratios of each estrogen to the macronutrients nitrogen, phosphorus, and potassium were also determined. Because manure application rates are typically macronutrient-based, estrogen to macronutrient ratios are proportional to areal mass application rates of estrogen to fields. Swine farrowing waste (from farrowing sows and piglets) had the highest ratios of E2 to macronutrients. Mean ratios in swine farrowing waste were roughly twice those in swine finishing waste (from growing male and nonpregnant female animals) and more than four times higher than those in dairy waste (from lactating cows in various stages of their reproductive cycles); these differences were statistically significant (α = 0.05). Estrone followed a similar trend. In contrast, ratios of 17α-estradiol to macronutrients were highest in dairy operations. These results can be used to better predict estrogen loading rates on fields receiving swine and dairy wastes. [ABSTRACT FROM AUTHOR]

The Engage initiative at the University of Tennessee addresses the needs of entering engineering students through a new first year curriculum. The program integrates the engineering subject matter of the freshman year, teaches problem solving and design by application, and seeks to address the increased retention and graduation of engineering students. Noteworthy curriculum features of the Engage program include a hands-on laboratory where students do physical homework to practice the concepts introduced in lectures, placing all freshman engineering students in a year-long team design curriculum, and a team training course where engineering upperclassmen are trained in team facilitation techniques and placed as facilitators with the freshman design teams. The Engage program was piloted during the 1997-98 academic year with 60 students. In 1998-99, the program was scaled up to 150 students, and fully implemented with the entire freshman class of 465 students during the 1999-2000 academic year. Engage students have shown a significant increase in academic performance compared to students following a more traditional curriculum. Graduation statistics show the positive long-term results of this effort. [ABSTRACT FROM AUTHOR]

Technoeconomic analyses using established tools such as SuperPro Designer® require a level of detail that is typically unavailable at the early stage of process evaluation. To facilitate this, members of our group previously created a spreadsheet-based process modeling and technoeconomic platform explicitly aimed at joint fermentative‒catalytic biorefinery processes. In this work, we detail the reorganization and expansion of this model—ESTEA2 (Early State Technoeconomic Analysis, version 2), including detailed design and cost calculations for new unit operations. Furthermore, we describe ESTEA2 validation using ethanol and sorbic acid process. The results were compared with estimates from the literature, SuperPro Designer® (Version 8.5, Intelligen Inc., Scotch Plains, NJ, 2013), and other third-party process models. ESTEA2 can perform a technoeconomic analysis for a joint fermentative‒catalytic process with just 12 user-supplied inputs, which, when modeled in SuperPro Designer®, required approximately eight additional inputs such as equipment design configurations. With a reduced amount of user information, ESTEA2 provides results similar to those in the literature, and more sophisticated models (ca. 7%–11% different). [ABSTRACT FROM AUTHOR]

The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and soybean production have intensified, a number of concerns have arisen due to the unintended environmental impacts on the ecosystem. Many areas across the Midwest are experiencing negative impacts on water quality, soil degradation, and increased flood risk due to changes in regional hydrology. The water quality impacts extend even further downstream. We propose the development of an innovative system for growing maize and soybean with perennial groundcover to recover ecosystem services historically provided naturally by predominantly perennial native plant communities. Reincorporating perennial plants into annual cropping systems has the potential of restoring ecosystem services without negatively impacting grain crop production and offers the prospect of increasing grain crop productivity through improving the biological functioning of the system. [ABSTRACT FROM AUTHOR]