Daina Briedis

Adhesion and lignin peroxidase production by the white-rot fungus Phanerochaete chrysosporium in a rotating biological contactor

This paper describes the adhesion and growth of Phanerochaete chrysosporium mycelium and subsequent lignin peroxidase activity obtained on polymer discs in a rotating biological contactor (RBC). The effect of support surface texture and polymer composition on biofilm adhesion was observed. Adhesion was enhanced on roughened surfaces compared to smooth surfaces. Discs made of nylon and polypropylene resulted in the greatest adhesion. Optimal culture conditions for fungal growth and enzyme expression in our RBC are described. A comparison of seven different media buffers showed that succinate and phthalate buffers resulted in greater lignin peroxidase activity than the more commonly used 2,2-dimethylsuccinate buffer. The addition of Tween 80 to cultures was shown to increase lignin peroxidase activity compared to cultures without Tween 80. A strain comparison in the RBC showed that the wild-type BKM-F-1767 strain adhered better to the support and produced higher enzyme activity than a mutant strain, SC26.

Evaluation of intrinsic immobilized kinetics in hollow fiber reactor systems

Immobilized cell and enzyme hollow fiber reactors have been developed for a variety of biochemical and biomedical applications. Reported mathematical models for predicting substrate conversion in these reactors have been limited in accuracy because of the use of free-solution kinetic parameters. This paper describes a method for determining the intrinsic kinetics of enzymes immobilized in hollow fiber reactor systems using a mathematical model for diffusion and reaction in porous media and an optimization procedure to fit intrinsic kinetic parameters to experimental data. Two enzymes, a thermophilic beta-galactosidase that exhibits product inhibition and L-lysine alpha-oxidase, were used in the analysis. The intrinsic kinetic parameters show that immobilization enhanced the activity of the beta-galactosidase while decreasing the activity of L-lysine alpha-oxidase. Both immobilized enzymes had higher Km values than did the soluble enzyme, indicating less affinity for the substrate. These results are used to illustrate the significant improvement in the ability to predict substrate conversion in hollow fiber reactors.

Engagement of millennial students using web-based screen movies to replace traditional lecture in lecture/lab courses

An emerging literature focuses on differences in learning style between the so-called millennial generation and preceding generations of students. Concurrently, engineering educators have developed a number of intuitions about millennial students, most with the common theme of lowered tolerance for lecture settings. Two current threads addressing the “lower attention span problem” are (a) approaches under the rubric active learning and (b) technology developments such as web-enabled screen movies and pod-casts. The second thread is often aimed at a technology “fix.” Experience shows that any technology fix is of itself minimal value. Specifically, our research question is the following: In traditional lecture/laboratory courses what is the effect of replacing lecture sessions with web-based, voice-over slide presentations punctuated with full screen demonstrations and interactive quizzes? We report results from a side-by-side study that replaces lecture with screen movies for three of ten lab sections in a high enrollment, computer tools and problem solving course. Results generally indicate no significant difference between the treatments for learning outcomes, attitudes towards engineering, and attitudes towards the screen movies. Student survey data indicates very favorable attitudes towards the screen movies in general. The results are encouraging given the early state of screen movie development.

Aligning Computing Education with engineering workforce computational needs: New curricular directions to improve computational thinking in engineering graduates

In this global economy, the preparation of a globally competitive U.S. workforce with knowledge and understanding of critical computing concepts is essential. Our CPACE (Collaborative Process to Align Computing Education with Engineering Workforce Needs) vision is to revitalize undergraduate computing education within the engineering and technology fields. Our objective is to design and implement a process to engage stakeholders from multiple sectors and identify the computational tools and problem-solving skills and define how these skills-directly informed by industry needs-can be integrated across disciplinary curricula. By explicitly integrating computing concepts and disciplinary problem solving, engineering graduates will enter the workforce with improved and practice-ready computational thinking that will enhance their problem-solving and design skills. We present the analysis of the computational skills and the strategies that we are using to map the workforce problem-solving requirements onto the foundational computer science principles. We outline the framework that we are using to identify opportunities for curricular integration between computer science concepts and the disciplinary engineering curricula. By documenting, evaluating, and making the process explicit, this process can serve as a model for national efforts to strengthen undergraduate computing education in engineering.

Modeling of crystal size distribution in a mixed suspension, mixed product removal crystallizer when growth is size dependent

Abstract A revised empirical two parameter size-dependent growth rate model proposed recently is discussed in detail and used to illustrate the analysis of both simulated and real population density and cumulative number oversize distribution data from a mixed suspension, mixed product removal crystallizer. The two-parameter model has superior curve-fitting properties compared with other models tested and shows improved consistency in the prediction of the growth rate in the case in which log population density plot exhibits curvature across a large crystal size range.

Work in progress: Integrating computation across engineering curricula: Preliminary impact on students

The Collaborative Process to Align Computing Education with Engineering Workforce Needs (CPACE) team developed a partnership among various stakeholders to identify the computational skills that are essential for a globally competitive engineering workforce. Our goal is to redesign the role of computing within the engineering programs at Michigan State University (MSU) and Lansing Community College (LCC) to develop computational competencies - informed by industry needs - by infusing computational learning opportunities into the undergraduate engineering curriculum. In this paper we summarize the process that we used to translate our research findings about the computational competencies needs in the engineering workplace into fundamental computer science (CS) concepts that can be used in curricular implementation. We also discuss the initial phase of our curricular implementation strategy in two disciplinary engineering programs at MSU and transfer programs at LCC.

Work in progress - effective engagement of millennial students using web-based voice-over slides and screen demos to augment traditional class delivery

An emerging literature focuses on differences in learning style between the so-called millennial generation and preceding generations of students. Concurrently, a number of intuitions have developed among engineering educators about millennial students, most with the common theme of lowered tolerance for lecture settings. Two current threads addressing the ldquolower attention span problemrdquo are (a) approaches under the rubric active learning and (b) technology developments such as web-enabled screen movies and pod-casts. The second thread is often aimed at a technology ldquofix.rdquo Experience shows that any technology fix is of itself minimal value. We focus on possibilities for improved instructional design. Specifically, our research question is the following: What is the effect of augmenting course material with web-based, voice-over slide presentations punctuated with full screen demonstrations and interactive quizzes? We report on our first steps to develop voice-over slide presentations with embedded quiz questions and full motion screen demonstrations in a web-accessible environment. Initial results focus on student attitudes based on data collected in Summer and Fall terms, 2007. Future work will include quantitative evaluation of learning outcomes.

SCALE-UP OF HOLLOW FIBER REACTOR SYSTEMS

Abstract Hollow fiber reactors have been developed for many biochemical and biomedical applications. In the study of these reactor systems, we have used single fiber reactors as a prototype for the larger hollow fiber cartridges. Experiments using single fibers have been conducted to obtain conversion data for reactor scale-up. We present a model for predicting conversions in bench-scale hollow fiber cartridges using these single fiber data. The model is compared to experimental conversion data and is shown to be a valuable design tool.

THE NARROWING OF CRYSTAL SIZE DISTRIBUTIONS IN A SONICATOR-MSMPR CRYSTALLIZER SYSTEM

Obtaining small crystals of a narrow crystal size distribution is an important problem in many pharmaceutical, biotechnological, and ceramic processing applications. This paper describes the use of a two-stage system to reproducibly produce pilot-scale quantities of a ceramic precursor powder. The population balance is used to determine the crystal size distributions obtained from a staged crystallization system. The staged crystallization system consists of two units, a mininucleator (sonicator) and an MSMPR crystallizer. Experimental and theoretical studies of this system showed that the use of the mininucleator leads to narrowing of the crystal size distribution obtained from the MSMPR crystallizer. The resulting expression for the population density distribution allows direct fitting of experimental log population density data from the second stage to determine the growth and nucleation kinetics for both the mininucleator and the MSMPR crystallizer

Limitations of the computerized ELZONE particle sizing system

The Particle Data computerized ELZONE system is a popular particle analyzer for liquid suspensions. Several limitations have been discovered in its ‘‘firmware’’ (a program stored permanently in read only memory) for quantitative volume and numbers distribution analysis. To enhance the versatility of the ELZONE firmware for user‐specific applications, independent data manipulation is recommended and discussed in this note.