David Norris - US grants

The acquisition of a radiation counting system will be utilized to further research in several areas including: steroid metabolism and its effects upon reproduction; the role of biogenic monoamines in metamorphosis regulation of glucose metabolism in premuscle of fasted and fed animals; regulation of the quiescent, resting states during the life cycles of invertebrates; and metabolic pathways involved in C3-C4 intermediate photosynthesis.

The vertebrate neuroendocrine system, using information derived from both internal and external environments, controls development, growth, and reproduction. The brain integrates this information and secretes neurotransmitters and neurohormones to alter pituitary function and bring about endocrine based events and behavioral changes. Such changes are very important in mediating major life events that help animals adapt to environmental changes. Because of the varied modes of reproduction that exist in teleost fishes, fishes are a useful system to look at how both the internal and external environments influence sex determination and sexual behaviors. One particularly useful mode of reproduction is a sexual plasticity known as sequential hermaphroditism where an individual can begin life as one sex, reproduce as that sex for at least one breeding season and subsequently undergo sex reversal and reproduce as the opposite sex. Such a change is accompanied by drastic changes in behavior. This system allows for investigation into the role of the brain in sex determination and sex-specific behavior. The purpose of the proposed research is to identify changes in monoamine neurotransmitters in the brains of a protogynous coral reef fish (Thalassoma duperrey) throughout the process of sex reversal and in relation to daily, semi-lunar and annual influences. Because there are relatively few vertebrates that exhibit a natural sex reversal once sexual maturation has been achieved, this system is an excellent model in which to look at changes in behavior and neurochemistry that accompany sex reversal and possible control mechanisms for such a reversal. This work will contribute to a better understanding of the relationship of neural control mechanisms for sex specific behaviors. By using animals which can act as both sexes in one individual at different times in the life history, one can gain a better understanding of how changes in sexual behavior may be controlle d in other animals, including humans. In addition the presence of diandry (two different male phenotypes, one being a male throughout the life history and the other being first female and then male) offers the opportunity to compare behaviors of two different types of males. The proposed work will provide information on the changes in monoamines associated with sex reversal and accompanying behavioral changes as well as some insights into possible cause-effect relationships. This system provides a unique opportunity for the study of neural correlates of sex determination and sexual behavior.

This grant supports the purchase of a Superconducting Quantum Interference Device (SQUID) magnetometer. The instrument satisfies the current need for a versatile magnetometer that will be used by four groups within the Department of Chemical Engineering and Materials Science (CEMS). The instrument will be employed in an array of projects including magnetic characterization of novel magnetic thin films and heterostructures, magnetic semiconductors, molecular solids, and magnetic nanostructures. This research is on structures that incorporate magnetic materials of many types, from organic magnets to conventional semiconductor and ferromagnetic metals, in a variety of configurations (magnetic semiconductor nanoparticles, single crystals and thin film heterostructures). It is this kind of engineering, where magnetic materials are incorporated into novel device structures, which has been so successful in terms of yielding useful magnetic devices such as Giant MagnetoResistance (GMR) multilayers, spin-valves, tunnel junction based Magnetic Random Access Memory (MRAM) and integrated magnetic metal/semiconductor structures. The intention here is to acquire a workhorse instrument that elevates magnetic characterization capabilities to the level of the materials fabrication and characterization expertise at CEMS, while simultaneously strengthening teaching and education in this area. This is essential to the challenging work of developing materials for spin-electronic devices of the future.

The broader impact of the proposed work lies primarily in the education and training of students in the interdisciplinary field of magnetic materials, an area in which the basic experimental skills are highly sought-after in many fields. These researchers will be from both Chemical Engineering and Materials Science programs at the undergraduate, graduate and post-graduate levels. In particular, undergraduate students will become actively involved with the research by taking advantage of the UROP (Undergraduate Research Opportunities Program) and REU (Research Experience for Undergraduates) programs.

CTS-0332484
D. Norris, U of Minnesota

This proposal aims to determine the mechanisms by which planar opals (i.e., crystalline layers of monodisperse submicron silica spheres) grow on substrates that are immersed in colloidal suspensions. Recent work has shown that such planar opals can provide a simple route to form photonic band gap materials. As photonic band gap structures can provide a novel material for controlling light, simple approaches to these materials are desired. However, the mechanism by which planar opals form is not understood. The proposed research will simultaneously pursue an experimental and theoretical investigation of planar opal growth. In experiment the team will use optical microscopy to visualize the growth of planar opals in real time with sufficient resolution to observe the motion of individual colloidal spheres. Theoretically, the team will examine the role of solvent flow through the pore space of close-packed spheres in the formation of planar opals. One graduate student, who is co-advised by the two PIs will be involved in both aspects of the project. The graduate student will be joined in experiment by an undergraduate student. The expected intellectual impact of this project is an enhanced ability to fabricate photonic materials and understand their properties. The project will also: provide a multidisciplinary environment to educate graduate students in the technologically important area of photonics; provide mentorship and an enhanced research experience for undergraduate students; and develop connections between academic and industrial researchers involved in both photonics and coatings technologies.

ABSTRACT - 0506672
University of Minnesota - Twin Cities

The amount of energy incident onto Earth from our sun is so large that covering only 0.1% of the earth's surface with solar cells that are 10% efficient could generate enough power to meet the current demands of the world's population. However, harnessing this energy with inexpensive materials and low cost manufacturing technologies remains an important challenge. While steady progress has been made in solar cells based on the p-n junction diode, the cost of producing electricity from sunlight is still 4-5 times more expensive than competitive technologies. The availability of sustainable and inexpensive energy sources strongly influences the quality of human life. For this reason, new developments in solar-toelectric conversion methods would impact everyone's lives.

We propose to establish an interdisciplinary research team that will focus on assembly and characterization of quantum-dot sensitized solar cells (QDSSCs) as well as on synthesis and characterization of its components. The QDSSC photoelectrode will be a macroscopic ensemble of 1-10 nm diameter semiconductor nanoparticles (e.g., CdSe, CdS, PbSe and Si ) attached to the periphery of 10-100 nm diameter wide band gap (ZnO and TiO2) semiconducting nanowires grown on a transparent conducting substrate. A thin layer of liquid electrolyte containing a redox couple will be sandwiched between this photoelectrode and a counter electrode to form the QDSSC. The macroscopic ensemble of nanometer size heterointerfaces between semiconducting nanoparticles and nanowires presents significant advantages both for light absorption and for charge separation, the two critical steps in solar-to-electric energy conversion. We propose to build solar cells that take advantage of (i) fast electron transfer across large interfacial areas, (ii) the ability to tune the absorption spectrum of nanoparticles to increase overlap with the solar spectrum and (iii) the possibility to generate multiple carriers per photon. This geometry is advantageous because photogenerated electrons in the smaller particle may be transferred to the wire and rapidly transported to a collection electrode while the hole is either transferred to an electrolyte or a hole conducting material. We propose to investigate (i) methods for synthesizing the components of the solar cell, (ii) methods for assembling these components into a functional device, and (iii) characterization of the solar cell, its components and the heterointerfaces, with particular emphasis on the interfacial electronic structure and electron transfer.

Intellectual Merit - The scientific underpinnings of photovoltaic technology are multidisciplinary and cut across traditional boundaries between physics, chemistry, engineering and materials science. The proposed research brings together fundamental studies in synthesis and characterization of nanoparticles and nanosystems, and organizes these efforts in a common goal, discovery of novel efficient solar-toelectric energy conversion methods. To accomplish our goals, we bring together an interdisciplinary team of investigators with expertise ranging from synthesis and assembly of nanostructures (Aydil, Kortshagen, Norris) to materials, interface and photophysical characterization (Aydil, Zhu, Norris) and solar cell design and development (Aydil). The research activities in each of these areas have the potential to advance our knowledge and understanding in interfacial chemistry and physics of semiconductors as well as in synthesis of nanostructured materials. Furthermore, the combination of the advances in these individual fields has the potential to lead to novel solar cells that can reduce our dependence on fossil fuels and the negative effects of burning fossil fuels on the environment.

Broader Impact - New developments in solar-to-electric conversion methods are of great interest to a wide scientific and non-scientific audience. Thus, the proposed project will not only have a broad impact but will also serve as an excellent vehicle for educating students and the general public; the project is a very concrete example of how nanotechnology can address one of the most pressing problems of the 21st century, availability of renewable energy. The PIs will supervise or co-supervise undergraduate students; host high school teachers, international visitors and faculty members from undergraduate institutions; visit high schools; and mentor students in university wide programs designed to increase the participation of disadvantaged or underrepresented groups in science and engineering. Specific examples of the PIs outreach activities are emphasized in Section 4, Results from Prior NSF Support. Such activities will continue with the present project.

The proposed research addresses several of the eight high-risk/high-reward research and education themes outlined in the NSF-NSE announcement. In the order of priority these are (1)
"Nanoscale Devices and Systems Architecture," (2) "Nanoscale Structures, Novel Phenomena and Quantum Control," and (3) "Manufacturing processes at the Nanoscale."

ABSTRACT
Proposal Number: CTS-0506748
Principal Investigator: Steven L. Girshick
Institution: University of Minnesota, Twin Cities
Proposal Title: NIRT: Manufacturing with Nanoparticle Sprays and Beams

Technologies that integrate the synthesis of nanoparticles and their controlled deposition onto surfaces will likely play an important role in the development of nanoparticle-based manu-facturing. An integrated program of research and education is proposed that will lead to a fun-damental toolkit for manufacturing with nanoparticle sprays and focused beams. Nanoparticle sprays, in tandem with a high-rate nanoparticle synthesis process, can be used to coat relatively large areas with nanoparticles. Focused nanoparticle beams, in concert with standard microfab-rication techniques, can be used to deposit lines or patterns, or to build three-dimensional ob-jects, made out of nanoparticles.
Processes will be developed in which materials and devices with different nanoparticle-based functionalities are manufactured using nanoparticle sprays and/or beams. This will be demonstrated by considering two different properties of nanoparticle-based systems: superhard-ness and photoluminescence. The long-term objective is to develop enabling technologies in which multiple nanoparticle-based functionalities could be integrated on a common platform.
"Fundamental toolkit" refers to the set of technologies that will be needed to synthesize and to deposit nanoparticles by sprays and focused beams, so as to create useful structures that ex-ploit specific properties of nanophase materials. The development of this toolkit will, in turn, require that key scientific and technical issues are addressed. These include fundamental under-standing of the interaction between impacting nanoparticles and surfaces; the mechanical behav-ior of nanoparticles and nanoparticulate structures; extending the performance of aerodynamic lenses to smaller particle sizes and narrower beam widths; and accomplishing gas-phase doping of luminescent nanoparticles.
The proposed research will serve as a springboard for a number of education and outreach activities. These include K-12 outreach through a local public school district; outreach to the general public in collaboration with the Science Museum of Minnesota; training of five graduate student research assistants in a highly interdisciplinary research environment; teaching of new interdisciplinary graduate courses on nanoparticle science and engineering; fostering greater in-volvement of women and underrepresented groups in our graduate research programs; and play-ing a leadership role in promoting nanotechnology activities in professional societies and gov-ernment agencies.
This NIRT project is co-funded by the Combustion and Plasma Systems and Nanomanufac-turing programs.

Weakly interacting colloidal particles, with uniform sizes ranging from several nanometers to microns, can spontaneously organize into close-packed crystals from concentrated liquid suspensions. Because they provide a simple, ordered structure with well-controlled and homogeneous porosity, these materials have been studied for many important applications, including sensing, separations,
microfiltration, and batteries. A particularly interesting and promising application for colloidal crystals is their role for fabricating photonic crystals. These crystals exhibit a band gap for photons, namely there exists a range of photon frequencies inside the material for which light cannot
propagate in any direction. This property could be utilized to manipulate photons for novel optical circuits, biological and chemical sensors, and efficient thermal emission sources. To advance all of these applications, there is a need for an efficient, low-cost means to manufacture large quantities
of high-quality colloidal crystals. Colloidal crystals have traditionally been made via the gentle sedimentation of spheres in a liquid suspension. This technique is ill-suited as a manufacturing process, since the settling rate is very slow, requiring months. If rushed, the resultant crystal is typically flawed by a significant amount of disorder. A process known as convective self-assembly can quickly, within hours, deposit colloidal particles into layers onto an inclined plate immersed within an evaporating liquid suspension.
Surprisingly, these vigorously growing layers are characterized by a nearly perfect, face-centered cubic (fcc) crystalline structure, the equilibrium packing for this system. The fast growth rate and high material quality make convective assembly an attractive candidate for a manufacturing
process for colloidal crystals. This research combines programs of computational modeling and experiments to understand the role of fluid flow and capillarity during the convective assembly of nanoscale, colloidal particles to form crystalline structures. Convective assembly processes have demonstrated greater production rates and higher material quality than achieved by classical particle settling methods. In this sense, capillarity and fluid motion coordinate a massive parallelization of particle interactions to achieve increases in production and quality; however, significant advances in understanding are needed
to harness this process to achieve industrial-scale measures of production, reliability, robustness, yield, efficiency and cost. This understanding will be critical for the development of large-scale, nanomanufacturing processes.
The societal benefits of this work will include the development of new approaches to nanomanufacturing, with longer-term benefits promised by the availability of nanoparticle-based crystalline materials that will impact applications for the environment, energy, and information technology.
Broader activities include the education of undergraduate and graduate students in nanotechnology, as well as an outreach program for the general public involving the Science Museum of Minnesota.

This project involves a collaboration between two research groups at the University of Minnesota (UMN) and one from the University of Duisburg-Essen in Germany (UDE). The goal of the research is to synthesize and study nanometer-scale semiconductor crystallites (or nanocrystals) in which impurities (or dopants) have been incorporated by design. Even without such dopants, semiconductor nanocrystals can exhibit unusual and useful physical phenomena due to their small size. The critical role that dopants play in semiconductor devices such as the transistor provides a strong motivation to study doped semiconductor nanocrystals. Doping can also address key problems in nanocrystal applications from solar cells to bio-imaging. As semiconductor nanocrystals already have commercial applications (e.g., in bio-imaging) and more on the horizon (e.g., tunable lasers, light emitting diodes, and solar cells), the research should provide further control over the properties of a useful class of materials. The collaboration includes researchers at UMN who are experts in solution-based synthesis of nanocrystals and at UDE who are experts in the chemical vapor synthesis of nanocrystals and their characterization using the extended X-ray absorption fine structure (EXAFS) technique. Project objectives include (i) the development of solution- and chemical-vapor-synthetic-methods to prepare doped nanocrystals and (ii) the use of EXAFS in conjunction with reverse Monte Carlo (RMC) simulations to determine the location of the dopant. A better understanding of the doping process should result.

In addition to the scientific goals, a major aim of this Materials World Network project is to provide future scientists with unique international research experiences. Students with such experiences benefit firsthand from observing how science bridges international differences. During the course of the project, 6 undergraduates and three graduate students from UMN will travel to Germany to perform research at UDE. For the undergraduate students, this will be incorporated into a research abroad summer program. For the graduate students, this can be arranged at a convenient time during their thesis project. Similarly, students from UDE will travel to UMN. These exchanges can also be facilitated by visits of UDE researchers to the US to perform EXAFS experiments at central beam lines (e.g., at Argonne National Laboratory). These visits will allow additional interactions between team members as well as analysis of samples prepared both at UMN and UDE.

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
CBET- 0854527
Ryan, Joseph
University of Colorado at Boulder

Endocrine-Disrupting Compounds in a Rocky Mountain Stream: Effect of a Major Wastewater Treatment Plant Upgrade


The multidisciplinary research team assembled for this proposal will apply an integrated chemical, biological, and hydrological approach in field and laboratory studies to investigate the relationships between nutrient loading, endocrine-disrupting compound release, and perturbations in the stream ecosystem and endocrine function of aquatic organisms. Joseph Ryan (University of Colorado), Larry Barber (U.S. Geological Survey), and graduate research assistant Jeffrey Writer will evaluate the fate and transport of a suite of endocrine-disrupting compounds in Boulder Creek. David Norris, Alan Vajda, and a graduate research assistant (University of Colorado) will experimentally evaluate the interaction between nutrient and EDC load on fish reproduction and periphyton communities using an innovative on-site mobile exposure laboratory. The team will collaborate to examine the effects of the changes in endocrine-disrupting compound and nutrient loading using in-stream analyses of aquatic bio-criteria indicative of ecosystem function. These integrated analyses will elucidate the role of engineering upgrades in sustainable watershed management.

The intellectual merit of the proposed research is increased understanding of the role of wastewater treatment in the preservation of human health and ecosystem function. Determination of the processes governing fate and transport of endocrine-disrupting compounds will elucidate and facilitate engineering and watershed management efforts to mitigate detrimental impacts on aquatic ecosystems. This unique and timely opportunity to evaluate the effect of a wastewater treatment plant upgrade on nutrient and endocrine-disrupting compound loading and ecosystem response will help water managers evaluate the efficacy of engineering solutions designed to restore environmental systems and protect water resources.

The broader impacts of the proposed research include dissemination of the results by a variety of means to training of new researchers in an important interdisciplinary area of environmental engineering. The principal investigators have been and will continue to participate in a wide range of community and watershed organizations to provide access to the results of this study, including the Boulder Creek Watershed Initiative, the Boulder Area Sustainability Information Network, the Watershed curriculum, the Colorado Riparian Association, and associated forums and workshops.

TECHNICAL SUMMARY
This award is made on a proposal submitted to the Cyberenabled Discovery and Innovation initiative. This award supports research to develop computational tools to study the interaction of light with nanostructured optical materials, also known as photonic crystals. These tools will be part of a computer aided design system that can be used to create new individual photonic crystals and new surface coatings that contain photonic crystals. Development will be guided by the needs of the community that designs and fabricates nanostructured materials. The system will be evaluated by using it to create a photonic crystal with specific optical properties. The investigation of how light interacts with nanostructured optical materials will lead to an understanding of complexity in a built system. The periodic layout and minute size of the constituent building blocks makes a photonic crystal geometrically complex. This geometric complexity leads to optical complexity because the full wave model of light must be taken into account, and diffraction effects must be considered. Finally, three distinctly different physical scales must be carefully modeled, from the structure of an individual photonic crystal, to the composition of a small volume of surface coating, to the scale of a small object covered with the surface coating. Computational thinking will be used to determine the structure of the system and to design individual modules within the system. A finite difference time domain technique will be used to solve physical optics problems for an individual photonic crystal, a ray tracing approach will be employed to perform geometric optics calculations for a surface coating that contains photonic crystals, and computer graphics rendering techniques will be utilized to depict the color appearance of the surface coating when applied to a three dimensional object. The powerful graphics processors available today on PC graphics cards will be employed to accelerate the finite difference time domain, ray tracing, and rendering algorithms. Novel numerical solution techniques will be explored to improve the performance of both the physical optics and geometric optics simulations.

The PIs will create a metallic photonic crystal that will improve the efficiency of incandescent light bulbs. Other novel thermophotovoltaic and plasmonic photonic crystals may be developed. As new surface coatings that reflect light in interesting new ways become available, the PIs plan to extend a variety of possible industrial and architectural designs.

NONTECHNICAL SUMMARY
This award is made on a proposal submitted to the Cyberenabled Discovery and Innovation initiative. This project addresses fundamental research issues in a topical area of electronic and photonic materials science having technological relevance. An interdisciplinary research team that includes a computer scientist, a materials researcher, and a mathematician will develop computational tools to design nanostructured optical materials, or photonic crystals. The computational tools will enable accurate calculations of how light interacts with photonic crystals which are materials that are structured to have a periodicity that interacts with light to lead to specific optical properties, such as particular frequencies of light which are not transmitted though the crystal. The computational tools that the PIs will develop will enable computer assisted design of photonic crystals with specific properties.

As a test of the computational tools, the PIs plan to create a metallic photonic crystal that will improve the efficiency of incandescent light bulbs. The PIs will also develop novel instructional materials to make the principles of photonic crystals accessible to the general public.

Intellectual Merit:

This collaborative research explores the fundamentals of microstructure and property development in coatings created from engineered latex particles developed at Arkema, Inc. Arkema is a leading supplier of specialty chemicals that are used in the coatings industry and has been an innovator in the development of synthetic routes to new latex particles. The University of Minnesota has developed advanced techniques to monitor structure and property development in situ during drying and via time sectioning methods in which the coating is frozen at different stages of structure development and then examined in the frozen state by cryogenic scanning electron microscopy (cryoSEM). The overall aim of the research is to advance the understanding of the film formation and structure development in latex coatings using model systems that are industrially relevant and well suited to fundamental research. Two novel latex systems will be explored in this research: (1) block copolymer latex and (2) fluoropolymer acrylic latex. The block copolymer latex consists of nanostructured particles with a combination of hard and soft blocks in a microphase separated nanostructure. The role of this nanostructure on film formation is not understood. The objective of this part of the research is to connect the nanostructure of block copolymer latex particles with the film formation process and the final structure of the coating. Model block copolymer latex with a range of chemistries and morphologies will be synthesized at Arkema. CryoSEM will be used to track the development of structure during film formation so that connections to nanostructure can be made. The stages in structure development, from discrete particles through compaction and deformation to the final coalesced film, will be imaged in frozen specimens. AFM studies will complement the research. With the fluoropolymer-acrylic latex, the main objective is to characterize film formation and relate the structure development to stress and cracking. Understanding and controlling cracking is important to the application of latex materials. Arkema will provide model materials formulated with and without a coalescing aid. CryoSEM studies will be carried out in parallel with measurements of weight loss and stress development and observations of cracking in order to determine the origin of the stress that causes cracking and the role of the latex particle structure on the phenomenon. The second objective is to use a broader set of particles to explore connections between particle and process parameters on cracking, and ultimately to develop strategies to mitigate cracks.

Broader Impacts:

This research will impact the fields of coating processing, colloidal science, materials characterization, and particle mechanics. The results will broadly apply to other latex materials, feeding a growing effort in industry to replace solvent based polymer coatings with water-based latex coatings. The research will help to advance the scientific understanding so that companies can meet the challenges they face as they seek to improve the environment. The impact of the research will extend to multiple groups of students. First, the research will help the career development of the graduate student as well as the undergraduate researchers, who will join the effort in the summers. These students will learn not only from the research itself but also from the interactions with academic and industrial scientists. Second, the graduate students in the home department of the academic PIs will have the opportunity to participate in an industrial roundtable that involves the Arkema PIs. Third, a new experiment will be designed for an undergraduate course in Materials Processing. The students will design coating formulations to make a Cool Roof? using the fluoropolymer acrylic latex. Lastly, the PIs will develop a learning module that introduces K-12 students to engineering concepts, an important topic in light of recent changes to the science standards in the State of Minnesota. The module will also be built on basic concepts in film formation and will include engineering of a Cool Roof. A high school science teacher will join the team to help with the research and the development of the learning module. The Arkema Foundation will make the learning module available through its summer program for science teachers.