Effects of Hofmeister Ions on Transition Temperature of Two Thermo-Responsive Polymers

It was hypothesized that through the use of Hofmeister Ions, the lower critical solution temperature (LCST) of poly(vinyl methyl ether) (PVME) and poly(ethylene glycol)- poly(N-isopropylacrylamide) (PEG-b-pNIPAAm) block-copolymer could be controlled. Through literature searches and small lab experiments, our team found that there may be a connection between Hofmeister effects and phase transition of a thermo-responsive polymer. To try and prove this, the lab team decided to take four cations (Mg2+,Na+, Cs+, K+) in solution with the thermo-responsive polymers and compared their LCST to solutions of the thermo-responsive polymer in de-ionized (DI) water. From this study, it was found that the addition of ions in solution lowered the LCST of PVME from 32°C to 26°C-30°C (depending on the ion added) and the LCST of PEG-pNIPAAm from 31°C to 26°C -29°C (depending on the ion added). The implications of this study could aid in efforts to manufacture better drug delivery devices, cell scaffolds, and tissue growth mediums. With increased control on the temperature at which a polymer undergoes a phase transition, the more effective these products can be in practice. The work will be continued by the next group of students

Biological Port Sampling Software (BIOSAMP) Development

The Northeast Port Biological Sampling Program collects marine organism lengths, length frequencies and age structures (otoliths, scales, spines, etc...) which are strategically requested to attain a representative sample of the associated federally managed stocks. Historically the biological sampling staff have used paper based data collection methods in the field and then transcribed this data into a web based data entry application. These methods are prone to error in legibility, transcription and data entry; an electronic data collection process will significantly reduce the quantity of errors, improve the efficiency of data collection activities and increase data quality. The Biological Port Sampling Software (BIOSAMP) will validate data during entry activities in order to prevent errors from occurring during data collection. This system will also reduce the time of data collection, minimize the delay between data entry and data access by end users, and minimize the need for data auditing and editing activities

Searching for Troposphere-Mesosphere Connections Using the ALO-USU Rayleigh-Scatter Lidar

The paucity of whole-atmosphere data introduces significant challenges that hinder the study of atmospheric couplings. The mesosphere in particular is a low-information void between the lower and upper atmosphere, which may prevent us from a complete realization of vertical interactions. The Rayleighscatter lidar at Utah State University’s Atmospheric Lidar Observatory (ALO-USU; 41.74° N, 111.81° W), operated with little interruption from 1993 to 2004, providing a valuable temporal and spatial (45 – 90 km) resource in this realm. When studied alongside a multitude of other atmospheric data sources, possible unforeseen connections or insights may result. In this study, an adaptive fit is applied to near-stratopause temperature data from the lidar and several assimilative models to identify simultaneous abnormal changes. A possible connection with tropospheric events is investigated as an example of future efforts that can be made to synthesize similar environmental figures where available

Design of Generalized Fiber-reinforced Elasto-fluidic Systems.

From nature to engineered solutions, the metrics of mechanical systems are often strength, power density, resilience, adaptability, safety, scalability, and the ability to generate the necessary forces, motions, and forms. The use of fluidic structures with fiber reinforcement to realize these metrics is seen throughout nature; however, these structures are rarely used by engineers, in part due to the absence of a generalized understanding of their kinematics and forces. Fiber-reinforced elasto-fluidic systems use fluid pressure to actuate an envelope with tuned compliance to provide desired motion, forces, flexibility, and transmission of energy. These structures combine the high strain energy utilization and flexibility of fibers, the versatility and compressive load abilities of fluids, and the continuum nature of soft materials, exploiting the best features of each. This dissertation discovered a vast array of previously unknown fiber-reinforced elasto-fluidic systems, models their mechanical behavior, experimentally verifies the models, creates methods for easy design synthesis, and applies this knowledge to multiple practical applications. Only a small subset of elasto-fluidic systems, popularly known as McKibben actuators, has been thoroughly investigated. Therefore, a vast design space of possible structures with multiple sets of fibers and different orientations yielding a rich array of functionality were yet to be investigated and applied to a wealth of applications. This dissertation develops the mechanics of generalized fiber-reinforced elasto-fluidic systems by first modeling the relationship of volume change and fiber orientation to motion kinematics and force generation. The kinematics of motions including translation, rotation, screw, bending, and helical were all modeled. Fiber configurations spanning the design space were tested to experimentally verify the predicted forces and motion. The force and kinematics were combined to form a design synthesis tool that maps the desired motions, freedoms, and constraints to fiber configurations. Synthesis methods were created for parallel combination of fiber-reinforced structures using discretized force and freedom directions. Lastly, novel applications were created using these fiber-reinforced elasto-fluidic structures, including an orthosis device for arm rotation contractures, a soft hexapod robot with an actuated flexible spine, and a structure for anchoring within pipes.PhDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107202/1/joshbm_1.pd

Patterns of in situ Mineral Colonization by Microorganisms in a ~60°C Deep Continental Subsurface Aquifer

The microbial ecology of the deep biosphere is difficult to characterize, owing in part to sampling challenges and poorly understood response mechanisms to environmental change. Pre-drilled wells, including oil wells or boreholes, offer convenient access, but sampling is frequently limited to the water alone, which may provide only a partial view of the native diversity. Mineral heterogeneity demonstrably affects colonization by deep biosphere microorganisms, but the connections between the mineral-associated and planktonic communities remain unclear. To understand the substrate effects on microbial colonization and the community response to changes in organic carbon, we conducted an 18-month series of in situ experiments in a warm (57°C), anoxic, fractured carbonate aquifer at 752 m depth using replicate open, screened cartridges containing different solid substrates, with a proteinaceous organic matter perturbation halfway through this series. Samples from these cartridges were analyzed microscopically and by Illumina (iTag) 16S rRNA gene libraries to characterize changes in mineralogy and the diversity of the colonizing microbial community. The substrate-attached and planktonic communities were significantly different in our data, with some taxa (e.g., Candidate Division KB-1) rare or undetectable in the first fraction and abundant in the other. The substrate-attached community composition also varied significantly with mineralogy, such as with two Rhodocyclaceae OTUs, one of which was abundant on carbonate minerals and the other on silicic substrates. Secondary sulfide mineral formation, including iron sulfide framboids, was observed on two sets of incubated carbonates. Notably, microorganisms were attached to the framboids, which were correlated with abundant Sulfurovum and Desulfotomaculum sp. sequences in our analysis. Upon organic matter perturbation, mineral-associated microbial diversity differences were temporarily masked by the dominance of putative heterotrophic taxa in all samples, including OTUs identified as Caulobacter, Methyloversatilis, and Pseudomonas. Subsequent experimental deployments included a methanogen-dominated stage (Methanobacteriales and Methanomicrobiales) 6 months after the perturbation and a return to an assemblage similar to the pre-perturbation community after 9 months. Substrate-associated community differences were again significant within these subsequent phases, however, demonstrating the value of in situ time course experiments to capture a fraction of the microbial assemblage that is frequently difficult to observe in pre-drilled wells

Constructing a man-made c-type cytochrome maquette in vivo:electron transfer, oxygen transport and conversion to a photoactive light harvesting maquette

The successful use of man-made proteins to advance synthetic biology requires both the fabrication of functional artificial proteins in a living environment, and the ability of these proteins to interact productively with other proteins and substrates in that environment. Proteins made by the maquette method integrate sophisticated oxidoreductase function into evolutionarily naive, non-computationally designed protein constructs with sequences that are entirely unrelated to any natural protein. Nevertheless, we show here that we can efficiently interface with the natural cellular machinery that covalently incorporates heme into natural cytochromes c to produce in vivo an artificial c-type cytochrome maquette. Furthermore, this c-type cytochrome maquette is designed with a displaceable histidine heme ligand that opens to allow functional oxygen binding, the primary event in more sophisticated functions ranging from oxygen storage and transport to catalytic hydroxylation. To exploit the range of functions that comes from the freedom to bind a variety of redox cofactors within a single maquette framework, this c-type cytochrome maquette is designed with a second, non-heme C, tetrapyrrole binding site, enabling the construction of an elementary electron transport chain, and when the heme C iron is replaced with zinc to create a Zn porphyrin, a light-activatable artificial redox protein. The work we describe here represents a major advance in de novo protein design, offering a robust platform for new c-type heme based oxidoreductase designs and an equally important proof-of-principle that cofactor-equipped man-made proteins can be expressed in living cells, paving the way for constructing functionally useful man-made proteins in vivo

Photo-physics and electronic structure of lateral graphene/MoS2 and metal/MoS2 junctions

Integration of semiconducting transition metal dichalcogenides (TMDs) into functional optoelectronic circuitries requires an understanding of the charge transfer across the interface between the TMD and the contacting material. Here, we use spatially resolved photocurrent microscopy to demonstrate electronic uniformity at the epitaxial graphene/molybdenum disulfide (EG/MoS2) interface. A 10x larger photocurrent is extracted at the EG/MoS2 interface when compared to metal (Ti/Au) /MoS2 interface. This is supported by semi-local density-functional theory (DFT), which predicts the Schottky barrier at the EG/MoS2 interface to be ~2x lower than Ti/MoS2. We provide a direct visualization of a 2D material Schottky barrier through combination of angle resolved photoemission spectroscopy with spatial resolution selected to be ~300 nm (nano-ARPES) and DFT calculations. A bending of ~500 meV over a length scale of ~2-3 micrometer in the valence band maximum of MoS2 is observed via nano-ARPES. We explicate a correlation between experimental demonstration and theoretical predictions of barriers at graphene/TMD interfaces. Spatially resolved photocurrent mapping allows for directly visualizing the uniformity of built-in electric fields at heterostructure interfaces, providing a guide for microscopic engineering of charge transport across heterointerfaces. This simple probe-based technique also speaks directly to the 2D synthesis community to elucidate electronic uniformity at domain boundaries alongside morphological uniformity over large areas