Browsing by Subject "Department of Chemical Engineering and Materials Science"

Now showing 1 - 20 of 21
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    Alcohol Dehydrogenases Deletion to Increase Yield of Isobutyrate
    (2011-09-06) Zhou, Jun
    Methacrylic acid is one of the most crucial chemical feedstocks in the material industry and there is a high quantity demand of methyl methacrylate (MMA) which is the ester form of methacrylic acid. Every year million tons of methyl methacrylate is produced to synthesize polymethyl metharylate (PMMA) which is a thermoplastic material and it is used as a light or shatter-resistant alternative to glass. Therefore, to come up with a method for producing methacrylic acid and methyl methacrylate becomes a popular topic of research in biosynthesis area. There are several traditional methods being used in the industry and the most common one is reacting acetone with hydrogen cyanide to generate acetone cyanohydrins and then treat it with sulfuric acid to form methyl methacrylate. However, because of side products and reaction condition, these two traditional methods require high quality of controlling harmful chemicals and hard to increase the yield of target product. What’s worse, the reactants are not renewable and emission will damage the environment. However, we have designed a new biosynthesis strategy to produce methacrylic acid. In this proposed work, glucose is converted to isobutyrate or 3-Hydroxyisobutyrate. By using oxidative dehydrogenation of isobutyrate and dehydration of hydroxyisobutyrate we could generate methacrylic acid
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    Assessment of Tissue Damage from Ultrasonic, Pneumatic and Combination Lithotripsy
    (2011-04-13) Cui, Yuqing; Sarkissian, Carl; Mohsenian, Kevin; Monga, Manoj
    Objective: To conduct a comparative evaluation of ultrasonic, pneumatic, and dual ultrasonic lithotripsy to predict the safety of probes on urinary tract tissue. Methods: Lithotriptors (medical device used to breakup kidney stones) tested were the Swiss Lithoclast Ultra (ultrasonic only - US, and ultrasonic-pneumatic combination US+P), and the Gyrus ACMI Cyberwand (dual ultrasonic). Fresh porcine ureters, bladders, and renal pelvis tissues were used for testing. A hands-free set up was used with each probe to vertically apply no pressure, 400 g, or 700 g of pressure for a duration of 3 seconds, 5 seconds or 180 seconds. Repetitive testing of each tissue/pressure/time combination was performed, for a total of 351 trials. Conclusion: All devices afforded a level of safety at tissue durations typical of inadvertent intraoperative contact (3-5 seconds), though the Lithoclast US-only was superior with regard to perforation for all tissue types. Overall, very similar results were observed between the Lithoclast US+P and Cyberwand.
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    Automated quantitative analysis of silica nanorod dimensions via watershed segmentation
    (2020) Quan, Michelle C.; Neal, Christopher A.; Calabrese, Michelle A.
    Quantifying the dimensions of silica nanorods often requires manual analysis of their dimensions, but this method is time- consuming and tedious. This work explores the potential for an automated analysis with Matlab to improve the efficiency of this analysis. The program described is a preliminary proof-of-concept version of a nanorod analysis program. Watershed segmentation and minimum-area bounding boxes are viable tools for the automated quantitative analysis of nanorod dimensions, and the automated process saves nearly one minute per particle compared to manual analysis. While the automated process shows promise, the program functions best with minimal nanorod overlap and requires more extensive testing to become feasible for widespread use. Improvements to noise reduction and particle shape prediction will expand the scope of images that can be subject to automatic analysis.
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    Characterizing the pH Dependence of Surface Charge for Silica Nanoparticles Made by Amino Acid Synthesis
    (2010-04-21) Zhang, Liang
    Silica nanoparticles are silica spheres in the micron size range. Because of their shape and ordered arrangement, these nanoparticles serve important purposes in high-tech industries and modern applications such as cancer therapy, drug and DNA delivery systems, ultrasensitive analysis, and nanoparticle films. Applications depend on order in packing of nanoparticles, which in turn depends on particle charge. Silica nanoparticles were synthesized using published methods and the pH of the solution bathing the nanoparticle was altered. The nanoparticle solutions were then characterized by size with SAXS lighting scattering and by surface charge with an electrophoretic method. Though zeta-potential tests provided variable data with each batch of particles, the overall pattern was consistent. It was found that zeta potential decreases as pH becomes more acidic.
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    Comparison of carbonylation in young and old rat skeletal muscle
    (2011-04-13) Willard, Isaac
    Proteins, DNA, and lipids in most tissues become carbonylated due to oxidative stress. Skeletal muscles are particularly susceptible to such carbonylation because of the conversion from metabolic energy to mechanical energy during contraction. This project focuses on the relative levels of carbonylation in intermyofibrillar mitochondria (IFM), the subsarcolemmal mitochondria (SSM), the cytoplasm, and the extracellular space of skeletal muscle. The morphology and function of muscle cells change in response to ageing and development. To measure the variance in carbonylation patterns with respect to both development and age, muscle tissue from young and old animals is analyzed. A labeling agent is used to label mitochondria red and carbonyl groups green. Confocal microscopy can take images of the labeled tissue and overlay them to show the mitochondria that have been carbonylated. The amounts of uncarbonylated and carbonylated mitochondria are compared between young and old tissue to determine how carbonylation changes with age.
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    Comparison of Tissue Remodeling in Engineered Vascular Grafts made from Adult and Neonatal Human Dermal Fibroblasts
    (2011-04-13) Chen, Minna; Syedain, Zeeshan; Tranquillo, Robert
    Tissue engineering provides a means for creating functional biological vascular grafts. A viable, strong, yet compliant, tissue-engineered vascular graft can be used as an alternative to native arteries in vascular surgeries and increase the quality of life for adults with heart disease, a leading cause of death in the United States. Previous work in the Tranquillo lab has shown that vascular grafts seeded with neonatal human dermal fibroblasts (nHDFs) can be engineered with burst pressures of up to 1600 mmHg. However, for the development of autologous vascular grafts for implantation, grafts seeded with adult human dermal fibroblasts (aHDFs) are more relevant. Previous work in the Tranquillo lab has shown that we can engineer grafts seeded with aHDFs to achieve burst pressures of up to 2200 mmHg, but that the remodeling of the fibrin scaffold and collagen production is significantly different between grafts seeded with aHDFs and those seeded with nHDFs. In this study, we analyzed methods to modify fibrin degradation by adult fibroblasts. In an earlier study, changing the initial fibrin concentration was shown to have a strong effect on the remodeling of engineered tissue. Further testing was performed by incubating aHDF grafts in conditioned media from nHDF grafts. Results showed differences from both changing the initial fibrin concentration and from adding conditioned media on tissue remodeling and collagen production.
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    Dynamics of Conjugation of Enterococcus faecalis
    (2009-09-23) Cui, Yuqing
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    Ethanol Production from Clostridium thermocellum
    (2010-04-21) Zhu, Tao
    The goal of this research project was to increase the total ethanol yield of Clostridium thermocellum. C. thermocellum is an anaerobic, thermophilic, cellulolytic and ethanogenic bacterium that utilizes cellobiose as a substrate to convert to ethanol. The advantage of growing these cells under high temperatures (60 oC) is that contamination factors are lessened as well as facilitating ethanol production. An ethanol tolerant strain (S4M0) was developed in the laboratory with a 4% ethanol tolerance and was compared to the wild type strain (WT) under fed-batch conditions. Fed batch culture involves injecting the cells with medium during the stationary growth phase to prolong cell growth and produce more ethanol. Under normal batch conditions, the WT and S4M0 cells both produced around 1 g per liter of ethanol.
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    Fabrication of Single Crystal Thin Films of La1-xSrxCoO3 on SrTiO3 (001) Substrates
    (2009-04-08) Schmitt, Joshua
    Complex oxides with perovskite structures offer an interesting and intriguing field of research for material scientists and physicists due to their wide range of electronic and magnetic properties like high Tc superconductivity, colossal magnetoresistance (CMR), ferroelectricity, spin state transitions etc. Although bulk La1-xSrxCoO3 has received considerable attention due to the existence of spin-state transitions, magnetoelectronic phase separation, and giant anomalous Hall Effect, a thorough and comprehensive study in thin films is still missing.
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    In vitro Toxicity Study of Noble Metal Nanoparticles with Varied Size, Geometry and Surface Chemistry
    (2010-04-21) Liu, Zhen
    The study of nanotoxicity is essential to evaluate the safety of human consumption and to inform the design of nanomaterials for biomedical uses. In this work, living cells were exposed to noble metal nanoparticles with varied size, geometry and surface chemistry in order to determine the effects these properties have on noble metal nanoparticle uptake and toxicity. Nanoparticles were synthesized using a variety of methods including surfactant templating, secondary deposition, and Ostwald Ripening under controlled light conditions in order to achieve nanomaterials with varied size and geometry. Surface chemistry was varied by surfactant exchange using charged thiols such as 11- mercaptoundecanoic acid and 11-mercaptoundecylamine to replace the initial surfactants, thus yielding nanoparticles with negative or positive z-potentials. Cellular uptake was measured using ICP-AES in exposed cells. Toxicity was assessed by MTT and hemolysis assays. In fact, both cellular uptake of nanoparticles and viability were dependent on the physical characteristics of the nanomaterials varied in this study.
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    Kinetics of Polybutadiene-poly(ethyleneoxide) Micelles in an Ionic Liquid
    (2009-04-08) Santiago, Jessica
    Amphiphilic block copolymers can form micellar structures when dissolved in a selective solvent, which are of interest in a range of applications. Once in solution, a dynamic steady state is established; however, in some cases the incompatibility between block and solvent prevents the realization of equilibrium, forming kinetically frozen aggregates. The expectation is that sufficient thermal energy may allow the locked-in micelle system to relax into a more stable conformation. In this experiment, polybutadiene-poly(ethylene oxide) (PB-PEO) micelles were prepared in the ionic liquid 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide [BMI][TFSI] via direct dissolution and cosolvent-aided dissolution using dichloromethane. Measurements of the hydrodynamic radii conducted by dynamic light scattering revealed the formation of micelles with drastically different average sizes in each preparation procedure. The thermally stable environment provided by [BMI][TFSI] then permitted the annealing of both samples at relatively high temperatures. The micelles formed by direct dissolution significantly decreased in size and width of distribution, in contrast to the cosolvent-produced micelles, which retained their smaller size and low polydispersity. Interestingly, the aggregates prepared by the two protocols yielded different micelle sizes even after thermal relaxation, suggesting the formation of a metastable morphology. These findings illustrate the strong path-dependence of micelle formation and relaxation.
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    Morphology and Crystallization of Hexatriacontane (C36H74)
    (2014-04-16) Hanson, Madeline
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    New method to convert heat directly into electricity
    (2011-11) Song, Yintao; Srivastava, Vijay; Bhatti, Kanwal; Leighton, Chris; James, Richard D.
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    Optimization of Engineered Cardiovascular Tissue
    (2009-04-08) Meier, Lee A.
    The ultimate goal of the field of tissue engineering is the ability to develop engineered tissues that exhibit physiologically relevant dimensions and mechanical properties such that utilization in a clinical setting is possible. While the most common approaches in this field have resulted in significant progress toward this goal's realization, in order to fully understand the cell developmental processes that guide tissue formation in vitro, as well as in vivo, a modified approach is necessary. The field of systems biology is emerging with the hope of solving this problem. Its purpose is to better understand complex cellular signaling interactions through mathematical modeling in order to develop statistical correlations within large sets of data obtained through interrogation of the biological system of interest. Developing statistical correlations between externally induced cellular signaling events and the resulting tissue phenotype can aid in elucidation of a predictive method for understanding how a cell population will respond to varying degrees of stimulation. The question posed is: if one knows the cell/tissue culture input stimulation(s), can the resulting tissue qualities be accurately predicted? A statistical method known as discriminant partial least squares regression is commonly employed for such analyses. This type of analysis relies on construction of a matrix (X) describing the signaling events induced within a population of cells in response to varying degrees of stimulation, as well as a second matrix (Y) describing the observed cellular response in terms of expressed phenotype. It is hypothesized that a solution to the expression Y=f(X) provides a well-defined description of the connected signaling events within the system of interest. Least squares regression methods have been empirically proven effective for such previously mentioned purposes. Neonatal human dermal fibroblasts (NHDF) and Fischer rat vascular smooth muscle cells (SMC) are of primary interest for this experiment. Two-dimensional cell monolayers were utilized initially and the experimental procedure will be later extrapolated to vascular, three-dimensional, fibrin-based tissue equivalents, in particular: tunica media-equivalents (ME). The Flexcell International FX-4000 cell culturing system was used to subject cultured monolayers to periods of cyclic distention/strain, as well as varying degrees of growth factor and supplement stimulation. Following distention and biochemical stimulation, cultures were lysed and the soluble fraction isolated. Subsequently, total protein content was determined and the samples were enriched for their phosphoproteins. Mass spectrometry was then employed to quantify the enzymatic activity within individual populations of cells. This analytical medium has elucidated significant phosphoprotein mass profile distinction between differentially stimulated cell populations. Statistical correlations between the input stimulation events and the resulting cell population's qualities such as the phosphoprotein mass profiles, total collagen and elastin content, as well as total cell number will be determined. From this, a cell-culture stimulation paradigm of steepest-ascent towards developmentally- and mechanically-optimized tissue-equivalents will be employed.
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    Poloxamer 407 as a Drug Delivery System to Treat Ear Infections
    (2021) Harris, Calvin; White, Joanna; Calabrese, Michelle
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    Preparing Arrays of Nanoscale Magnetic Dots to Be Used for Future Extremely High Density Recording (EHDR) Hard Drives Using Block Copolymer Thin Films and Spin-on Glass
    (2009-04-08) Spanjers, Charlie S.
    As the hard drive industry reaches a limit in storage density using conventional techniques, there becomes a need to create magnetically isolated nanodots that may allow for higher density recording. To do this, block copolymers have been proposed to be used as templates for fabricating large-scale arrays of these magnetic dots. When spin coated into a thin film, polystyrene-polyisoprene-polylactide (PS-PI-PLA) triblock terpolymer self assembles into a hexagonally packed lattice of cylindrical features perpendicular to the surface. After degrading the cylindrical component (PLA), we are left with an array of holes (antidots). The immediate goal of my research has been to use the described polymer film as a template for fabricating magnetic dots. Previous research has used this method to create 40 nm dots.
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    Synthesis of Copper Zinc Tin Sulfide Nanoparticles
    (2011-04-13) Ammerman, Lauren
    Many solar cells are made with relatively rare (and therefore expensive) materials, and some, like lead and cadmium, are hazardous to the environment. Thus, efforts are being made to make solar cells from readily available, non-hazardous materials that retain or exceed the efficiency of those that are already being produced. One promising material is copper zinc tin sulfide (CZTS). However, the solar cells made from bulk CZTS are not sufficiently efficient to replace those currently on the market. Because of this, research in the use of CZTS nanoparticles for solar cells is in its early stages. I synthesized CZTS nanoparticles, with a special emphasis on the ratio of copper to zinc (normally 2:1) and whether variation of this ratio had any effect on the electronic properties of the nanoparticles. Though additional tests are needed to ascertain the exact effect on electronic properties, there was a correlation between the Cu:Zn ratio and absorbance, strongly suggesting a variation in band gap.
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    Triggered Degradation of Polyacrylamide Gels for DNA Recovery
    (2011-04-13) Wagner, Kristen
    Polyacrylamide gels are commonly used in the analysis and separation of DNA by gel electrophoresis. In some protocols, once a sample of DNA undergoes gel electrophoresis, the DNA sample is recovered from the gel. A common method of doing this is to soak pieces of gel in buffer and wait for the DNA to diffuse out of the gel. This can take many hours or even days for DNA strands longer than 500 base pairs. It would be extremely useful to incorporate a chemically triggerable release mechanism into the polyacrylamide gel that would allow a researcher to decompose the gel network at will and recover the embedded DNA more quickly. We have developed a bis(acrylamide) crosslinker that contains a chemically cleavable group. Polyacrylamide gels made with this crosslinker (“EG2”) decompose quickly when exposed to a DNAcompatible reductants. In principle, due to the shortened time span, less stable nucleic acids such as RNA might be recovered with a reduced amount of decomposition of the actual RNA sample.