Home Institution: Xavier University
Major/Minor: Physics/ Mathematics
MRSEC Mentor: Uwe Kortshagen
Porosity Studies of Germanium Nanocrystal Thin Films
In this study we are interested in comparing the N2 adsorption/desorption results with those of other previously used techniques (namely SEM and RBS) since the N2 technique is well accepted and the other techniques are not. Digitally reconstructed porous domains contain statistical information well beyond the pore level and thus constitute accurate models that can be used to relate the porosity of these films not only to their microscopic properties, but also to their electrical and optical properties. As part of this study, we would like to measure the porosity of films composed of ~4-5nm germanium nanocrystals and voids (ranging from ~1-55% the density of bulk germanium by other estimates.) The goal of this research is to report a theoretical and simulation study of the temperature dependence of adsorption hysteresis for porous matrices having different morphologies and topologies.
Home Institution: Bowdoin College
Major/Minor: Chemistry/Mathematics
MRSEC Mentor: Wei Shen
Bimolecular Fluorescence Complementation (BiFC) of Enhanced Yellow Fluorescent Protein (EYFP)
Enhanced Yellow Fluorescent Protein (EYFP) belongs to a family of naturally fluorescing proteins which have found extensive use as molecular detectors in cell biology. When split to form two approximately equal-sized polypeptides, the individual fragments do not fluoresce. We intend to restore fluorescence by coupling the EYFP fragments in close proximity through complementary nucleotide binding and allowing them to self-reassemble. We will express our proteins in a modified BL21 E. coli host strain which is able to biotinylate a target sequence on the C-terminal and N-terminal fragments. Biotin-streptavidin binding is then used to form complex with a pair of complementary oligonucleotides. After reaction, reconstruction of the fragmented EYFP-streptavidin-oligonucleotide is assessed by fluorimetry.
Home Institution: University of California Santa Barbara
Major/Minor: Physics/Chemistry
MRSEC Mentor: Eray Aydil
Experiments in PbSe quantum dot sensitized solar cells utilizing ZnO nanowires
Quantum Dot Sensitized Solar Cells have recently come of interest over traditional Dye Sensitized Solar Cells (DSSCs) because Quantum Dots (QDs) both absorb over a greater portion of the solar spectrum and have the unique characteristic of being able to produce multiple electron-hole pairs for an individual photon. We will be utilizing solar cells consisting of PbSe QDs attached to ZnO nanowires grown from sputtered ZnO because nanowires provide a direct electrical pathway to the photoanode, reducing the possibility of electron-hole recombination, resulting in greater quantum efficiencies and increasing electron transport. The goal of this research is to use novel techniques to successfully create a Quantum Dot Sensitized Nanowire Solar Cell because they may exhibit greater overall efficiencies compared to DSSCs.
Home Institution: Saint Mary's University of Minnesota
Major/Minor: Physics/Chemistry
MRSEC Mentor: Chris Macosko
High Shear Rheometry for Coating Liquids
A recent study by Davies and Stokes (J. Non-Newtonian Fluid Mech. 148 (2008) 73-87) has suggested that accurate high shear rheometry is achievable through the use of commercial parallel plate rheometers, so long as the gap setting is very low, on the order of 10 µm. The goal of this project is to reproduce the procedure outlined by Davies and Stokes and assess the accuracy of any data obtained through the use of narrow gap parallel plate rheometry. This research could very well prove to be important for industrial coating processes, as many such processes are performed at high velocities and narrow gaps. These factors, in turn, lead to high rates of shear, making accurate rheological measurements at such high rates all the more desirable.
Home Institution: University of Wisconsin Madison
Major/Minor: Electrical Engineering
MRSEC Mentor: Steve Campbell
Plasma Synthesis of Silicon-based Nanocrystals
Silicon nanocrystals (Si-NCs) have a variety of uses in electronics and photovoltaics. For example, bulk silicon is not a useful material for constructing LEDs; however, when it is broken into pieces two to six nanometers in diameter it gains interesting optical properties. A photon will be emitted when an electron and hole recombine due to a UV photon being incident upon the surface. The crystalline size determines the wavelength of the emission. Using plasma to synthesize nanocrystals is an efficient technique. We plan to study the effects of surface damage on the quantum yield of Si-NCs by reducing ion bombardment. To accomplish this, an aluminum shield will be placed within the etching plasma. The ultimate goal is to increase the overall quantum yield of Si-NCs.
Home Institution: Univeristy of Michigan
Major/Minor: Chemistry with minors in Physics and Math
MRSEC Mentor: David Norris
Fabrication of sub-micrometer scale photonic crystals using soft lithography
Photonic crystals have become of interest for many applications including thermovoltaics and optical computing due to the existence of a photonic band gap. The recent developments in lithography have made possible the fabrication of photonic crystals with small enough feature size that a band gap in the visible range of light is possible. Traditional techniques for fabrication of photonic crystals are limited by the poor resolution and thermal stability of photoresists. Likewise, scalability issues obstruct the large scale development and commercialization 3D photonic crystals. The project uses recent discoveries in soft lithography to develop techniques for tungsten photonic crystal fabrication more suitable for conversion to mass production.
Home Institution: Penn State Hazleton
Major/Minor: Biology (Vertebrate Physiology option) and Biotechnology
MRSEC Mentor: Dan Frisbie
Synthesis of Ladder-Type Oligomers As Organic Semiconductors
Organic semiconductors are materials with extended conjugated pi-electron systems allowing for delocalization. Both molecular structure and solid state packing are important in realizing useful materials. The project aim is to design new organic semiconductors and to refine the synthesis process. The target molecules are ladder-type fused heterocyclic aromatic compounds structurally related to oligoacenes. These molecules have an emphasis on shape in hopes that they will demonstrate better packing in the crystalline state and produce an increase in charge mobility. These compounds also have various heteroatoms including sulfur, nitrogen, and oxygen. This project involves synthesis, purification, and characterization of the solid state structures of these materials. Crystal structure will be determined when we succeed in growing suitable crystals.
Home Institution: Howard University
Major/Minor: Biology/ Chemistry minor
MRSEC Mentor: David Odde
Analysis of dynamic instability of microtubules by tracking fluorescent proteins
The cell cytoskeleton is responsible for the structure, stability, intracellular transport, and extracellular translocation of the cell. Of the 3 types of fibers that compose the cytoskeleton, microtubules control various cell movements including transport of membrane vesicles, cilia and flagella movement, and chromosome alignment/separation in cell division. A unique feature of microtubules is dynamic instability which allows them to grow and shorten rapidly at opposite ends. Through imaging of fluorescently labeled microtubule-associating proteins (MAPs), the methods by which microtubules lengthen and shorten will be analyzed to further knowledge of ways to influence cell growth and proliferation.
Home Institution: Missouri Science and Technology
Major/Minor: Chemical Engineering
MRSEC Mentor: Marc Hillmyer/Dan Frisbie
The Characterization of Block Copolymers for Organic Electronic Applications
Organic photovoltaics (OPVs) offer a tractable pathway for solar energy conversion because they are solution processible and their electronic properties can be tuned through manipulating their chemistry. Poly(3-hexylthiophene) (P3HT) is one of the best performing and most studied polymers in the field of organic electronics. While many researchers use P3HT in OPV devices, molecular and structural characterization of the polymer is commonly overlooked and this leads to a large variability in device performance between groups. We will study the molecular and structural properties of block copolymers using size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), and atomic force microscopy (AFM). By studying these polymers in a systematic way, we hope to understand how the molecular and structural properties of the polymers affect device performance.
Home Institution: Florida A&M
Major/Minor: Civil and Environmental Engineering
MRSEC Mentor: Marc Hillmyer
Biorenewable Polymers: Polymer Synthesis and Material Properties
Most polymers are currently made from petroleum. Due to the shortage of oil, and its resulting high cost, it is ideal to use a non-petroleum based source as a feed stock for plastics and other polymer materials. We are working in the general area of developing polymer materials from renewable resources, such as crops. The polymer that we are working with is called polylactide, which is derived from corn.
Home Institution: University of Arizona
Major/Minor: Chemical and Environmental Engineering
MRSEC Mentor: Jeff Derby
A theoretical study of the effect of the accelerated crucible rotation technique (ACRT) on CdHgTe crystals grown in a vertical Bridgman system
The focus of this project is to simulate the growth of single-crystal cadmium mercury telluride (CdHgTe, or CMT), a semiconducting material whose main application is infrared detection. In a vertical Bridgman system the material is heated to a temperature above its melting point and then slowly translated through a decreasing temperature gradient, causing the melt to solidify. By implementing the ACRT mixing is enhanced in the melt, reducing compositional non-uniformities which is vital for crystal functionality. The system is modeled using equations of fluid flow, heat and mass transfer, and solid-liquid interface shape. The model, Cats2D, uses the Galerkin/finite element method to discretize the partial differential equations.
Home Institution: University of Minnesota
Major/Minor: Electrical Engineering
MRSEC Mentor: Dan Frisbie
Probing of the organic semiconductor ultra thin film
The majority of charge transport in an organic semiconductor occurs at the organic semiconductor/ insulator interface, within the first few mono layers of the organic film. The morphology of the organic semiconductor at this interface affects the electrical performance of an organic thin film transistor
Home Institution: College of Menominee Nation
Major/Minor: Mathematics
MRSEC Mentor: Jim Kakalios
Minimizing the Staebler-Wronski Effect in Amorphous Silicon Film
In the search for alternate energy sources, we continue to try to improve some of our known resources. One of these valuable and highly potential resources is the well known solar power. During this era of international research toward the affects of global warming within our atmosphere, there has been found a reversible photoelectric effect that decreases both photoconductivity and dark conductivity within solar cells. Amorphous Silicon produced by glow discharge Silane is used to fabricate thin solar cells with improved efficencies. This material has proven it has high optical absorbtion within the visible light spectrum and our ability to control its conductivity with dopants. These techniques offer a hopeful cost effective, more efficient solution to our valuable natural resources.
Home Institution: Trine University
Major/Minor: Chemical Engineering
MRSEC Mentor: Michael Tsapatsis / R. Lee Penn
Effect of Diameter on Band Pattern Formation of Silica Nanoparticles
Films of silica nanoparticles have many applications in diverse fields such as molecular separations and electronics. In the process of producing coatings of silica nanoparticles by convective assembly, an interesting phenomenon occurs where the silica nanoparticles form a periodic band pattern instead of covering the glass substrate. The band pattern will be studied to see the effect of particle diameter on the spacing between the bands. Silica nanoparticles of different sizes will be grown and coated onto a glass substrate. The spacing of the bands will be observed with the scanning electron microscope. After producing and analyzing the particles and coatings, the spacing of the bands will be able to be predicted based on particle size.
Home Institution: Florida A&M
Major/Minor: Biochemistry and Biology
MRSEC Mentor: Chun Wang
Targeting Antigen Presenting Cells for Vaccine Delivery
Dendritic cells (DCs) are a special type of antigen-presenting cells that are capable of ingesting foreign materials (antigens), thereby stimulating antibody production and cellular immunity. DCs are found in the skin, inner lining of the nose, lungs, stomach, intestines, spleen and lymph nodes. DCs can also be found in the blood in an immature state. The goal of this research is to develop polymer particles as carriers for delivering DNA vaccine specifically to DCs, while avoiding other non-DC cells. To accomplish this long-term goal, it is important to understand how different cell types take up polymer particles with different sizes. In this summer project, we investigated how DCs and other types of cells such as macrophages, fibroblasts, and epithelial cells take up particles 0.1 µm and 1µm in diameter in vitro and quantified and compared the dependence of particle uptake on cell type and particle size. This preliminary work will provide important insight for developing better vaccine delivery systems.
Home Institution: Rutgers
Major/Minor: Physics; Minors: Education, Mathematics
MRSEC Mentor: Xiaoyang Zhu
Quantitative FRAP Measurements of Lipid Bilayers
A fundamental issue in biophysics is the nature of lipid bilayers. They are what cell membranes are comprised of, and are therefore of importance in developing drug delivery systems. These bilayers serve also serve as a great model for boundary mechanics and cell membranes are important areas in modern research. This serves as model for boundary mechanics. Lipids chosen for their liquid and gel states are being studied with interfacial force microscopy. In parallel to this study is the development of a system for quantitative lipid bilayer diffusion experiments using fluorescence recovery after photobleaching (FRAP). Pedagogical research is also a driving force, in that a lab assignment for undergraduate students is being established.
Home Institution: University of Minnesota
Major/Minor: Chemical Engineering; Minor: Chemistry
MRSEC Mentor: Efie Kokkoli
Delivery and Controlled Release of Drugs into Cancer Cells using pH-Sensitive Liposomes
The usage of pH-sensitive liposomes provide as a method for controlling the release of encapsulated contents such as drugs to combat cancer cells. Under physiological conditions, a pH-sensitive liposome is stable, but it quickly deteriorates in more acidic environment during endocytosis. The capability of a liposome is enhanced via various methods: steric stability and lengthened bloodstream circulation time are facilitated by incorporating poly(ethylene glycol) to the liposome surface. Furthermore, attached are fibronectin-like peptide sequences seeking specifically an integrin over-expressed by colon cancer cells. Fluorescent marker contained inside the liposomes is the means for characterizing pH-sensitive liposome functions in CT26 colon cancer cells. Data from flow cytometry and confocal imaging demonstrates the efficacy of this method of targeting water-soluble drug delivery.
Home Institution: University of St. Thomas
MRSEC Mentor: Dan Frisbie
Field-Effect Transistors Based on CdSe Nanocrystal Film
The unique size tunable properties of semiconductor nanocrystals (SC NCs) make them a promising material in the application of future electronics and optoelectronics, where thin film of semiconductor layer is necessary. However, the insulating nature of NCs, especially due to their organic ligand shell, inhibit charge conduction through the film; limiting the application. The goal of this research is to first address this issue and obtain highly conductive NC films and second to understand the electrical properties of the film. Specifically, a film of CdSe NC doped with Ag in a field-effect transistor (FET) configuration will be used in order to amplify charge carrier concentration. Also, the ability to control the semiconductor charge carrier concentration in a FET will best allow us to understand the film’s electrical properties.
Home Institution: Penn State, Hazleton
MRSEC Mentor: Dan Frisbie
The Impact of Strong Electron Acceptors on Molecular Structure and Solid State Packing of Substituted Oligothiophenes
This project involves the synthesis, characterization and crystal growth of a series of structurally related molecules through the Knoevenagel reaction. The purpose of this work is to investigate the impact of the cyanovinylene groups on the packing patterns of these molecules in the solid state. Previous work in our group on dicyanovinyl and tricyanovinyl groups suggest that strong sulfur-nitrogen interactions tend to force planarity of these materials while the strong acceptor groups resulted in lowering the LUMO levels and induced π -stack formation. Condensation of aromatic aldehydes with acetonitriles through a simple Knoevenagel reaction will be carried out using various commercially available starting materials. Crystal growth by slow evaporation and/or sublimation followed by x-ray single crystal structural analysis will be carried out on those materials.
Home Institution: Minneapolis Edison
MRSEC Mentor: Kevin Dorfman
Bringing Microfluidics and Soft Lithography to the High School Laboratory
Material and equipment costs have prevented new research techniques from being used in high schools. Fortunately, recent research into microfabrication alternatives has considerably reduced the costs of microfluidics and soft lithography. In this project, the classic toy, Shrinky Dinks, is used to make molds formerly created on silicon wafers. The patterns are easily created by printing designs onto the Shrinky Dink plastic using a standard laser printer. When heated, the plastic and the ink patterns shrink to about one-third their original length and width, while becoming nine times thicker. Inexpensive elastomers, such as PDMS, can then be used to create channels and stamps from the Shrinky Dink molds. The result: low-cost, cutting-edge techniques that can be easily used in high school laboratories.
Home Institution: Coon Rapids High School
MRSEC Mentor: Uwe Kortshagen and Eray Aydil
Dye-Sensitized Solar Cells for the High School Chemistry Lab
Dye Sensitized Solar Cells are relatively simple to construct in a research laboratory. Complicated or expensive materials and construction techniques have been modified or eliminated to achieve a DSSC possible for the high school chemistry lab. Iodolyte has been replaced by an electrolyte solution of acetonitrile, potassium iodide, and iodine.
Home Institution: Coon Rapids High School
MRSEC Mentor: Eray Aydil
Creating Dye Sensitized Solar Cells for the Physics Classroom
Traditional solid state solar cells do not help to fix the current energy crisis we are experiencing. In order to create an efficient and productive type of cell new materials must be explored. Nanocrystalline dye-sensitized solar cells are a promising technology to help solve our current energy dilemma. Nanoparticles offer advantages over traditional designs. Nanometer sized objects have large surface areas, possess unique optical and physical properties, and are relatively inexpensive. Currently dye-sensitized nanocrystalline TiO2 solar cells have created conversion efficiencies of sunlight to electrical power of more than 10% . We will be using “homemade” dye, found in various organic substances, including blueberries and raspberries, to see how they behave as dyes and to determine if electrical output can be increased. In addition, we will be varying TiO2 film thickness to see what effect, if any, it has on electrical power output. The goal of this research is ! to create a step by step laboratory experiment that uses simple, inexpensive ingredients for students to create their own solar cells. From there a myriad of inquiry based labs can be performed that can enhance students’ knowledge about optics, electricity, and quantum phenomena.
Home Institution: Curie High School — Chicago Public Schools
MRSEC Mentor: Michael Tsapatsis
Formation of Lysine-Silica Nanoparticles
This research reports on the advanced application of formation of Lysine and Silica nanoparticles which have increased significant attention for preparing silica nanoparticles by addition of TEOS (tetraethylorthosilicate) to an unbuffered, aqueous solution of lysine. The need for well-defined silica nanoparticles has increased and has potentials to meet this need as an immune protection for animal –to-human islet transplantation by producing fabrication of monodisperse of Silica nanoparticles using Lysine in order to adjust the pH of the silica-lysine sols and encapsulating living cells. Researchers have interest in the pig solution to make islet transplantation.
Funded by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-1420013
UMN MRSEC
435 Amundson Hall, 421 Washington Ave. SE, Minneapolis, MN, 55455
P: 612-626-0713 | F: 612-626-7805