Xanthan gum (XG), a biopolymer excreted by bacterium Xanthomanoas campestris, is used in pharmaceuticals, cosmetics, agricultural products, food products, industrial products, and is used in enhance oil recovery processes because of its properties as a thickening agent, dispersion agent, and stabilizer of emulsions and suspensions.  Locust bean gum (LBG), a polymer extracted from the seeds of the carob tree (Ceratonia siliqua), is of interest in the biopharmaceutical field as a medium for oral drug delivery.  With the addition of nanoparticles, the material properties of the polymer solutions can be significantly altered.   Understanding of polymer-particle interactions and their impact on the material response to shear through rheological measurements is necessary for targeted design of material properties for specific applications. Flow and oscillatory testing was performed on XG and LBG solutions with and without the addition of silica dioxide (SiO₂) nanoparticles.  Under constant shear, XG solution shows a shear thinning behavior typical of weak gels.  With the addition of nanoparticles, the shear thinning behavior of XG is still present but at an overall higher viscosity.  LBG shows shear thinning behavior with a Newtonian region at lower shear rates.  The addition of nanoparticles to solution shows a region of shear thickening at lower shear rates and shear thinning behavior at higher shears at a considerable higher overall viscosity than the LBG solution without nanoparticles.  When strain is held constand with increasing frequencies, the storage (G') and elastic (G'') modulus show that XG has a tendency of more elastic behavior than LBG.  The addition of nanoparticles results in more viscous solutions with a higher elastic response.  LBG behavior is mroe  heavily impacted by the addition of SiO₂ nanoparticles than XG.

With efforts being made to remove human impact on the ecosystems surrounding us, underwater ambient noise is a topic of interest. Understanding and even mitigating this ambient noise has come to be of foremost importance in various fields. To understand underwater noise, it is best to first have a well-developed understanding of noise in general and what it is about noise that we should concern ourselves with. Starting first with sources of sound, such as that of a person singing, can provide an introduction into how to process sound measurements underwater. By working with recordings in “.wav” form I was able to convert to a spectrum, or spread of frequencies, that can be read in terms of the frequency and underwater pressure, two important aspects when studying underwater ambient noise. Using a numerical computation language (GNU Octave) to analyze sound data, I was then able to see plots of these spectra as well as to generate Pressure Spectral Density plots. I was then provided guidance regarding how to interpret these plots and apply this knowledge to various locations, a necessary introductory step in the overall process. Understanding ambient noise in general, as I was able to start doing this summer, and then taking it further to understand ambient noise in our area, is the first step towards curbing disturbances to our marine ecosystems.

Current estimates place pancreatic adenocarcinoma within the top ten deadliest diagnosed cancers in the US and #1 for mortality (~98%, five years after diagnosis). Consequently, early detection and the study of its pathology are paramount. Typically, this is accomplished through microscopy of flat specimens that are taken from tissue core (TC) biopsies (d=400-1200 µm) of a patient's pancreas. In the Human Photonics Laboratory, we are attempting to enhance diagnostic sensitivity by using a 3D microscopy system, originally designed for single cells, to image entire 400 μm diameter TCs. Imaging thick, opaque TCs requires specimens to be optically cleared and stained. Therefore a microfluidic device (MD) was developed to prepare pancreas (pTCs) and agarose hydrogel (aTCs) cores in an "all-in-one" approach that simplifies, automates and preserves the 3D structure of TCs. Flow and diffusion properties for bulk tissue in MDs deviate from the well-characterized properties of single cells. Subsequently, designing the initial MD required investigating histological dye diffusion and fluid flow with TCs. We found transparent 1% agarose were a suitable pancreas substitute for observation/measurement of volumetric diffusion in an open chamber. In comparison, pTCs needed to be cut open for subsequent analysis. Initial results demonstrate that by 30 min, most dyes completely diffused through larger (L=10 mm, d=2 mm) aTCs, but concentration profiles between dyes varied. Although the density and stiffness of aTCs matched pTCs, diffusion differed, as dye in pancreas samples diffused only 12% as far as in agarose. Properties of dye diffusion into aTCs with flow were then studied on a smaller scale in a test microfluidic channel (L=5.2 cm, d=720 µm). A slow flow rate of 80 µL/s was created by a variable-height gravity line system. Initial results demonstrate that slow flow rates significantly attenuated dye diffusion into aTCs, but allowed the aTCs to remain stationary.

 With an international focus on limiting greenhouse gas production, advancements in biomass conversion are needed. Conversion of biomass into more convenient fuels can lead to carbon neutrality. Biomass has the potential to be converted to transportation fuels after undergoing oxygen-free thermochemical decomposition, known as fast pyrolysis, and upgrading in a Fluid Catalytic Cracking reactor. Wood, one form of biomass, is largely made up of cellulose, hemicellulose and lignin. Lignin is comprised of polymers constructed of p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol monomers. In the present project, pyrolysis of these monomers will be modeled using phenol, guaiacol and syringol, respectively. Individual monomers and mixtures of monomers will be pyrolyzed using a Pyroprobe and the bio-oil contents will be quantified by gas chromatography-mass spectroscopy. It is expected that when combinations are pyrolyzed, the bio-oil production will be suppressed due to secondary reactions of each monomers’ product. As combinations of these monomers are characterized, pyrolyzed lignin can be characterized. Eventually, all aspects of pyrolyzed wood will be characterized and optimum conditions for pyrolysis of woody biomass can be assessed, thus yielding the highest quality bio-oil.

Waves carry a significant amount of energy, but this energy has not been thoroughly explored for human use. There are a myriad of different ways to harness this energy. One very promising method is through the vertical oscillation of a buoy as waves pass beneath it. The Applied Physics Lab (APL) has teamed up with Oscilla Power to test an APL buoy design paired with an Oscilla power generator. This pairing has been tested over a matter of months on Lake Washington, just off of Sand Point. The buoy itself is anchored to the bottom of the lake by three anchors, and a weight consisting of two railroad wheels hangs in the water column beneath the buoy. The Oscilla Power energy-generating device attaches mid-line above the hanging weight. There are a number of data acquisition devices onboard measuring the motion of the buoy via accelerometers, the loading on the tether, and electrical output of the Oscilla Power device. The results of this test show a relation between wave height and power output via tether loading, verifying the buoy design. Optimal power output coincides with optimal wave heights and frequencies, and the results of this test and subsequent data analysis reveal these values. This information is crucial to the design of future moorings for wave energy conversion devices. This work may be scaled up to provide power to open ocean research buoys, extending the battery life of these devices. If these tests are promising, additional uses for this energy on a larger scale could be explored.

Heart disease and stroke are the first and third leading causes of death for men and women in the U.S. and together account for more than a third of all U.S. deaths. It has been shown there is a correlation between decreased intercellular forces in the endothelial cells in the artery and higher permeability of the arterial lining. This can lead to atherosclerosis, a disease defined by hardening of the arteries, a major underlying cause of heart attacks and strokes. The focus of this research was to determine how different blood flow rates affect the intercellular forces of the endothelial cells that line the arterial wall. The first step was to fabricate microposts. Negative molds of the posts were cast off of a master array of microposts for which the spacing, height and diameter of the microposts were known. A positive mold was then cast off of the negative mold to produce a substrate on which the cells could be cultured. Next a flow chamber was designed for these experiments. Human Pulmonary Artery Endothelial Cells (HPAECs) were then cultured and transferred onto the microposts which were stamped with fibronectin, a protein that would help the cells bind to the tips of the microposts. The stamping portion of the experiment required much trouble shooting and ultimately the experiments were halted here. If the research had continued the experiments would have run for 14 hours, after which the cells would be fixed in place, stained with a fluorescent dye and imaged using microscopy. These images would then be transferred to a custom written Matlab code that would calculate the deflection of the microposts and the forces induced by cells. This data could then be used to determine the effect of varying blood flow rates on the permeability of the arterial wall.