Sixty seven CSU undergraduate students had the opportunity to work on research projects with faculty mentors during Summer 2013. Fifty three proposals were received from five colleges with requests totaling $413,242. With the generous support of the Provost's office, 35 proposals were funded across 15 departments for a total of $249,820.
The Poster Session took place on September 5, 2013 from 10 a.m. to 2 p.m. in the Atrium of the Student Center.
Jeremy Adato and Norbert Delatte
Pervious concrete is a type of porous portland cement concrete with interconnected voids. This material has been increasingly used to reduce the amount of stormwater runoff from paved areas. It has also been shown to improve the water quality near low volume and low speed pavements as well as in parking lots. Due to the low compressive strength of pervious concrete associated with the high void content, it currently is not used in highway structures except perhaps as an overlay for conventional concrete pavement. The large, open pore structure of this material allows water to pass through its structure, thereby helping to reduce the deleterious effects of storm-water runoff. Since pervious concrete is a relatively new type of material, standard methods for testing its performance characteristics are currently being developed. For this purpose, a total of 42 pervious concrete cylinders removed from different field installations in the United States were collected and studied. Density, void ratio, hydraulic conductivity (falling head method) of pervious specimens was evaluated. UPV tests were conducted on all specimens and the results were compared to develop the use of UPV to estimate the properties and performance of pervious concrete.
Combining Orthogonal tRNA/synthatase Pair and Amber Codon Suppression to Genetically Encode Oxidative Damage in High Density Lipoproteins
Jaclyn Alatrash, Nicholas Gilliam, Alisha House, and Valentin Gogonea
Apolipoprotein A-I (apoA-I) is the main protein constituent of high density lipoprotein (HDL - the “good cholesterol”). Oxidatively damaged apoA-I has been isolated from circulating plasma and atherosclerosis plaque with the amino acid residue tryptophan 72 (W72) of apoA-I identified as a primary oxidation site. ApoA-I designed to include specific oxidized amino acids can be used to further investigate the role of site-specific oxidative damage in atherosclerosis. Genetic encoding of oxidized amino acids through orthogonal tRNA/aminoacyl-tRNA synthetase (aaRS) pairs offers a reliable method for producing site-specific oxidized proteins. Our project involves the generation of Saccharomyces tryptophan-RS mutants for recognition of oxidized tryptophan (ox-W) but not naturally occurring tryptophan. To study the role of oxidative damage on HDL function we need oxidized proteins that mimic the oxidatively damaged protein observed in vivo. Thus, our goal was to produce site-specific oxidized apoA-I (ox-W72) for incorporation into reconstituted nascent HDL. The two aims we hope to achieve within this project are 1) to provide targeted mutations that increase the specificity and affinity of aaRS towards 2-hydroxy-W-apoA-I, as well as 2) express and confirm the presence of ox-W72 in modified apoA-I.
Rachel Andrikanich, William Hein, and Jeffrey Dean
African Clawed Toads turn toward waves created by prey. We studied turning of four frogs. We concentrated on body movement, leg action and hip, knee and ankle movements, classified respectively as pushing/pulling or extension/flexion/ return. As expected, we observed symmetrical patterns for left and right stimuli. Very rostral stimuli (+- 30 °) generally elicited a forward movement as the legs extended and pushed; hips extended while knee and ankle movement varied according to turn angle. More lateral and caudal stimuli commonly elicited an initial backward movement of the rear of the body as one or both legs pulled, reflecting hip flexion. Knee and ankle movement again varied by turn angle and together with the pulling initiated body rotation. Turning usually continued with a sweeping push by the contralateral leg, involving hip and knee extension and knee flexion. Overall leg movement patterns are similar when compared amongst frogs though the strength of joint flexion and extension vary. Variation in joint movement may be influenced by the overall size of the frog.
A Quantitative Evaluation of Growth in Leptodea Fragilis Before and After the Arrival of Zebra Mussels in Lake Erie
Elizabeth Barkett, Robert A. Krebs, and Matthew T. Begley
The arrival of zebra mussels in the Great Lakes in the 1980’s marked several environmental changes, most notably in freshwater mussels in the Unionidae. There are no studies of population demographics of native Great Lake species before this period of time. In this study, several recent shell collections of Leptodea fragilis, a fast-growing freshwater mussel, were made on various beaches along Lake Erie. To compare the effects of the zebra mussels on L. fragilis, we compared growth rates, determined from size and estimated age of shells, to additional collections of L. fragilis from 1941 to 1967available at the Cleveland Museum of Natural History. The growth rates of this species are exceptional for their speed among freshwater mussels. A modern comparison of growth rates and age are presented with a sexually dimorphic unionid river species, Lampsilis siliquoidea, that were collected in Summer 2013. We hypothesized that the arrival of zebra mussels could affect the growth rate of L. fragilis by selecting on age of reproduction or growth to reach a minimum size for reproduction, results that could shift growth curves and/or age demography of current populations, and help them persist where zebra mussels remain abundant.
Taylor Barto, Holly Warner, Rick Rarick, and Dan Simon
Above-knee amputees who use a prosthetic leg typically have to compensate for its shortcomings with unnatural hip motions. This compensation eventually leads to adverse health issues such as arthritis. We propose an active prosthesis to improve performance. The motor in our prosthetic knee allows the patient to move his hip normally, thus reducing the possibility of ancillary health issues. To improve the efficiency of the prosthesis, we use the braking phase of the prosthesis to regenerate energy. By storing energy in a supercapacitor during braking, the prosthesis lasts longer between each charge than it would without regenerative braking. We are considering two knee motor designs—a gear drive and a ball screw drive. Both designs appear to have the potential for regeneration. Several parameters characterize the prosthesis design. We use biogeography-based optimization (BBO) to determine these parameters. We are currently optimizing the prosthesis design to achieve accurate tracking of the knee angle. Future optimization criteria will include efficient energy use and generation.
Examining the Levels of Microcystin and Nutrient Inputs and Their Effects on Lake Quality in Cuyahoga County, Ohio
Tom Bienvenu and Julie Wolin
The purpose of this project is to acquire baseline understanding of the urban lakes in Cuyahoga County, Ohio. The researchers used canoes, a Van Dorn water sampler, 63μm Wisconsin net, and a modified Livingstone corer in the lakes to collect water, plankton, and sediment samples from the lakes that were visited. The Northeast Regional Ohio Sewer District (NEORSD) will analyze the water samples for quantitative and qualitative levels of microcystin. The remaining samples including diatoms in the sediment and the plankton in the water will be analyzed by the researchers in the labs at Cleveland State University. The data collected can be combined with the National Lake Assessment (NLA) to better understand and utilize the natural services provided by lakes in urban ecosystems. The project is in the data collection stages and has not yielded any results yet, although it is hypothesized that the lakes with less artificial inputs and a larger buffer area should have lower risk of harmful algae and higher levels of water quality.
Dustin Bowden and Joanne M. Belovich
Microalgae is a promising biofuel feedstock for replacement of conventional transportation fuels. Microalgae does not require arable land for cultivation, and the biofuel production rate per acre of land is an order of magnitude greater than that needed for crop-based production methods. Though microalgae to biofuel processes are attractive, none have proven commercially successful due to the high costs of algae dewatering. Moreover, the scarcity of fresh water in many parts of the world prevents development of this process because of competition with drinking water supplies. Our lab has developed an efficient dewatering method using an inclined gravity settler. It is possible to adapt the freshwater Scenedesmus dimorphus to brackish water, without significantly changing growth rate nor lipid content. In this research, we investigate whether this saltwater-adapted algae species can be dewatered using the gravity settling method.
The settling velocity was measured by a settling column using absorbance at 600 nm to measure cell concentration. Our preliminary results yielded settling velocities of 0.76 cm/h, which is similar to earlier measurements of 0.87 cm/h for freshwater S. dimorphus. Based on these settling velocity measurements, we have found that saltwater acclimation will have minimal effect on the separation efficiency of S. dimorphus.
Climate Change from Oxygen Isotopic Variation of Pore Water from Sediments in Punderson Lake, Northeast Ohio
Rachel Daley and Fasong Yuan
The environment in Ohio has changed over time. The hydroclimate, which is the climate of the water, shows changes from the Industrial Revolution to the present. Evidence for these changes can be found in levels of δ18O and δ2H isotopes in the layers of sediment and water in the lakes of Northeast Ohio. Mass spectrometry can be used to test the levels of δ18O and δ2H isotopes from pore water samples within sediment cores. In this study, surface soil and water samples were collected from cores in Punderson Lake at Punderson State Park in Newbury, Ohio. Pore water was extracted from the sediment core every centimeter. Next the oxygen isotope composition (δ18O) and the levels of δ2H of the pore water in the sediment layers were measured using a Picarro Cavity Ringdown Spectrometer. A record of the δ18O and δ2H of Punderson Lake was then recorded to determine the climate variability over a period of approximately 350 years. Changes in the δ18O and δ2H of lake water can be used to see changes in precipitation and water balance. Determining past climate and hydroclimate changes can help us predict future changes in the climate of Northeast Ohio.
Annie Djukic, Omri Tayyara, Deborah Espy, and Majid Rashidi
Research supports the idea that dynamic control of both a person's center of mass and base of support are necessary to prevent falls, and that older adults can learn this combined control through specific balance training. Effective balance training requires a large number of repetitions of task-specific practice. Externally induced movements have been employed in balance studies both to test and train balance responses, most often using mechanized surface perturbations. These systems however are quite expensive; therefore, we chose to investigate a more cost effective solution focusing on surface translation for balance training in our lab.
We performed a literature review of balance testing or training studies which had successfully used a translating surface paradigm. The motion parameters and subject characteristics were compiled (Table 1) to arrive at a decision about the parameters to be designed into our device. The device was designed to meet the space and subject use needs, compiled motion parameters, and engineering and safety requirements. A scotch yoke mechanism was chosen as well as a DC Motor and an appropriate gearbox, which were designed to translate, via a steel arm, a plywood and square tubing platform.
Steven Drellishak, Marina Bykova, and G. Valentin Börner
Successful reproduction of Saccharomyces cerevisiae relies on the organism’s ability to complete the meiotic cell cycle and produce viable gametes. Zip1 is a protein that constitutes the central component of a protein structure that connects homologous chromosomes known as the synaptonemal complex. Zip1 is important for progression through the meiotic cell cycle. The C terminus of the coiled-coil Zip 1 protein is responsible for localization to the axes of the chromosomes. An internal deletion near the C terminus of Zip1, called zip1-c1, yields a stronger meiotic arrest than a mutation where Zip1 is completely deleted. The more efficient meiotic progression in a Zip1 deletion mutation versus the zip1-c1 mutant suggests that zip1-c1 prevents an alternative pathway of meiotic progression. A genomic screen of the Nasmyth genomic library revealed candidate plasmids N5 and N89 containing yeast genes which, when overexpressed, increase spore viability and bypass meiotic arrest in the zip1-c1 mutant. This has implications that the genes on the overexpression plasmids serve some function in correcting mistakes in meiosis when Zip1 is mutated.
Alex Farmer, Jeffery Allen, Matt Egizii, Paul Skalski, and Kimberly Neuendorf
YouTube is an online media site with over one billion hours of user-generated content, and a monthly worldwide viewership averaging over six billion hours. This volume motivates advertisers to reach out to this enormous audience. Advertisers wish to capture the attention of an audience, avoid causing annoyance, and minimize intrusiveness. In this study, a YouTube video tutorial has been used to create five conditions testing reactions to nondiegetic advertising. Participants will be shown one of five versions of the tutorial. Each version includes either no advertisements, or one of the following: A TrueView video advertisement that is not skipped, a TrueView video advertisement that is skipped, a banner advertisement that is not cancelled, or a banner advertisement that is cancelled. Both type and level of intrusiveness of the ad have been manipulated. During viewing, eye-tracking analyses will monitor fixations in specified look zones, and elsewhere onscreen, testing ad attraction and distraction. After viewing, participants will complete a questionnaire designed to elicit their reactions to the advertisement, and ascertain the effect that the advertisement may have had upon their memory/recall, whether or not the level of intrusiveness decreased their enjoyment of the tutorial video, and other advertising and video outcomes.
Functional Morphology of Rat Hands and Feet: Correlation with the Ability to Grip Tree Branches During Locomotion
Jessica E. Fonce and Andrew R. Lammers
Anatomy and function are usually closely related. Since locomotion on tree branches is common among mammals, we expect to find that the anatomy of the hands and feet is well-suited toward gripping narrow, cylindrical, branch-like substrates. We hypothesize that the ability of rats to grip arboreal supports relies on musculature responsible for adducting the first digit (thumb and big toe) and opposing medial-most and lateral-most digits. We dissected the hands and feet of four rat cadavers. There is a substantial muscle that may be responsible for the flexion/adduction of the thumb in the hands. We also found lumbricals, and dorsal and palmar interossei. These muscles are responsible for flexing metacarpophalangeal joints as necessary for gripping, or for adducting digits. Foot anatomy looked very similar to that of the hands. Based on the anatomy alone, rats are built for locomotion across cylindrical branches as well as terrestrial substrates. We trained four live rats to walk on cylindrical trackways, 2 cm and 1 cm in diameter. We videotaped these rats as they walked on the branch-like supports so that we could determine how they use their hands and feet to grip. We are still in the process of processing the data collected.
Controlling the Size and Shape of Polypeptide Colloidal Particles: Temperature Dependence of Particle Formation
John P. Gavin, Nolan B. Holland, and Kiril A. Streletzky
A promising approach for developing new drug delivery vehicles is by using stimuli responsive hydrogel nanoparticles. Polypeptide surfactants designed in our lab have been shown to form micellar particles of varying sizes and shapes depending on the solution salt concentration. These responsive polypeptide surfactants consist of a small charged protein domain (foldon) with three elastin-like polypeptide (ELP) chains forming a three-armed star polymer. The size and shape of the micelles they form is dependent on the ratio of total ELP volume to head group area. By introducing linear ELP into the ELP-foldon solution, the total volume of ELP in the aggregate would be increased if the linear ELP is incorporated in the micelle. This method could control the particle size and shape. To determine if the linear and three-armed ELPs co-assemble, we have observed aggregation as a function of temperature using turbidity measurements in a UV-vis spectrometer. We have found that higher concentrations of linear ELP increases the difference in transition temperature between the linear and three-armed ELP. At these higher ratios, the linear ELP aggregates prior to micelle formation. When the ELP-foldon subsequently passes through its critical micelle temperature, they break down the linear ELP aggregates resulting in smaller colloidal emulsions. Light scattering will be used to characterize the size and shape of these aggregates.
Eugene Groff, Stefan Vladan Blagojevic, Taras Koshylovskyi, and Haigang Zhou
“Quadrophobia” is a relatively novel term that corresponds to a type of ‘fear’ or ‘misrepresentation’ that can manifest itself during the process by which companies report their earnings per share (EPS) values to the public. This study sought to conduct an in-depth examination into the process by which company's reported their respective EPS amounts, in order to determine the degree to which they manipulate the fourth number after the decimal place to bolster their perceived value. Our research focused on analyzing the actual v. reported EPS data (via Worldscope) of various companies being trading on different exchanges throughout the world, and from these sets of data, ascertaining the fundamental causes for quadrophobia and possible solutions to this pervasive problem. Our analysis concludes that a higher degree of quadrophobia was prevalent in developed countries, than in emerging markets.
Taliesin Haugh, Geoffrey Horn, Arvin Mathur, and Phillip Wanyerka
To most Clevelanders, the west bank of the Flats brings to mind the bustle of busy nightclubs or the rusting facades of Cleveland’s now fading steel industry. Few people would generally associate this area with archaeology, let alone remember that during the nineteenth century this area was home to one of Cleveland’s earliest and most influential ethnic communities. Known as Irishtown Bend, many Irish immigrants made their way to this close-knit, working class neighborhood of small ramshackle houses crammed closely together along the narrow bluffs of the Cuyahoga River. Most of the arriving Irish immigrants who came to Cleveland beginning in the 1820’s and 1830’s sought jobs working as laborers either on the construction of the Ohio and Erie Canal or on the city’s docks as the shipping industry began to rise. Irishtown Bend thrived throughout the nineteenth century. The types and qualities of artifacts analyzed from Irishtown Bend can be used to offer a wealth of detailed information on the social, economic, and political life of one of Cleveland’s earliest ethnic communities. Thus this project has shown how archaeology can be used as a critical tool to help inform and help shape our ideas about Cleveland’s urban “melting pot.”
Bethany Hollowell, Timothy Klypchak, Katherine Taylor, and J. Mark Souther
Our project examines themes in African American history from the 1910s to 1970s through the lens of Cleveland, drawing upon the voices of more than 60 Clevelanders interviewed by our team. After collecting more than 60 hours of digital sound using oral history best practices, we produced minute-by-minute logs to aid researchers, created a selection of short story clips for the Cleveland Voices website, and curated new sites for the Cleveland Historical mobile app. Among our interviewees are the oldest living eyewitness of the 1920 Matewan Massacre in the coalfields of West Virginia, the first African American licensed pilot, and the first black architecture firm owner in Ohio. Many of our interviewees were participants in the Great Migration or Second Great Migration. Some have firsthand experience of sharecropping in the South in the early 20th century, and their local experience covers Cedar-Central, Glenville, Mt. Pleasant, and the Heights. Topical strengths within this new oral history series—part of the 900+ interview Cleveland Regional Oral History Collection—also include black music, leisure, and recreation venues, black suburbanization, school desegregation, housing discrimination (including hate crimes), fair housing activism, and urban riots.
Mary Jacobson, Hailee Houston, and Andrew Slifkin
Physiological health has been linked to increased complexity in the output of physiological systems. For example, as the severity of cardiac disease increases, EKG time series show reduced complexity. The present study investigated the relation between mental health and complexity in motor output. In particular, we tested the hypothesis that depression severity—as measured by the Symptom Checklist-90-R (SCL-90-R)—should be negatively correlated with motor output complexity. Measurements of motor output were obtained when participants generated long sequences of movements in a cyclical aiming task. The resultant movement amplitude time series were submitted to spectral analysis, from which an index of motor output complexity was derived. According to the results, low levels of depression severity were associated with power spectra tending toward white noise (high complexity) and high levels of depression severity were associated with power spectra tending towards pink noise (low complexity). The results appear to support the hypothesis that depression severity and motor output complexity are negatively correlated.
Seol Kim and Anthony J. Berdis
Approximately 4,000 children in the United States are diagnosed each year with a brain tumor. Brain cancers are the deadliest of all pediatric cancers as they have survival rates of less than 20%. Typical treatments include surgery and radiation therapy. However, chemotherapy is the primary therapeutic option for children, especially against aggressive brain tumors. An important chemotherapeutic agent is temozolomide, an alkylating agent that causes cell death by damaging DNA. In this project, we tested the ability of non-natural nucleosides developed in our lab in order to increase the ability of temozolomide to kill brain cancer cells. Our results show that combining low doses of our nucleoside with temozolomide kills more cells compared to treatment with either compound individually. The increase in efficacy is specific for temozolomide as similar effects are not observed in cells treated with other chemotherapeutic agents such as cisplatin, 5-fluorouracil, and taxol. High-field microscopy techniques demonstrate that the combination of our nucleoside and temozolomide causes cell death via apoptosis as opposed to necrosis. A model is provided describing how our novel nucleoside analog increases the cell-killing effects of temozolomide by inhibiting the misreplication of damaged DNA created by this agent. Collectively, these studies provide pharmacological evidence for a new treatment strategy to more effectively treat patients with brain cancers.
Hannah Krainz, Katie Huskey, Mary-Francis Miller, Christina Dennis, and Holly Holsinger
The vision of The Department of Theatre and Dance’s Intersection Project was to provide points of intersection between artists and community with experiences that all creative artists share, focusing especially on inter-generational exchanges. One element of the Intersections Project was the collaborative creation of an original performance entitled Ancestra. Four student researcher/performers joined twelve Cleveland performance artists, ages 18-73, to create and present the docu-performance, Ancestra. Research for this project focused on the transcript of the 1853 National Women’s Rights Convention held in Cleveland, OH as well as other primary sources from the Women’s Suffrage Movement. The group also examined epigenetic scientific discoveries, which hypothesize that humans are genetically linked to the experiences of ancestors as well as their physical traits. These two lines of research provided the basis for a rich conversation between past and present which was integrated into the performance. Women in the project also researched their personal histories and wrote poetry, prose, and dialogue based on themes, memories, and experiences. These writings, together with the research discoveries were montaged into the final script which was rehearsed and performed in a “work in progress” showing at CSU on August 2nd, followed by a discussion about the work and process.
Daniel Kulman, Janine Naim, and Bin Su Ph.D.
Copaiba oil derived from the oleoresin of the Copaiba tree has been widely used as an antiseptic and expectorant for the respiratory tract, and as anti-inflammatory agent in various skin diseases. Studies have indicated that Copaiba oil exhibited anti-carcinogenic properties in various preclinical studies. However, the anti-cancer mechanisms of copaiba oil still remain unclear. There are various diterpenoid compounds within Copaiba oil, which also make the mechanism investigation very difficult. Hardwickiic acid (HAA), a clerodane diterpenoid isolated from Copaiba oil shows anti-chaperone activity from a recent study. In the current study, cytotoxicity and anti-chaperone assay guided isolation led to 9 fractions from Copaiba oil. Three of the fractions showed cytotoxicity in prostate cancer cells. And other three fractions exhibited potent anti-chaperone activity. There are multiple chemical components in the fractions that showed cytotoxicity, which has been confirmed with mass spectrum. The three fractions showed anti-chaperone activity were further purified for structure elucidation. NMR combined with MS reveal that the three fractions are Copaibic acid, Hardwickiic acid and 7-Acetyl-copaibic acid. All three compounds can be used as lead compounds for the development of more potent small molecule chaperone inhibitors.
Paul lkanich, Pratheek Koneru, and Robert Wei
Plants are widely considered the most cost effective and environmentally friendly way to clean soils and waters contaminated with toxic metals, e.g. arsenic and mercury. We have focused our research on the uptake of arsenic and its biochemical effect on two species of fern, Spider brake fern and Christmas fern. Spider brake fern is known to be capable of accumulating significant amounts of arsenic. We wish to determine whether the levels of arsenic uptake in Christmas fern are comparable to Spider Brake fern (>1g kg-1 plant biomass) when both are grown under the same conditions. Another aim of the research was to see whether these plants respond differently to the arsenic stress. For that purpose, we used a technique referred to as one and two-dimensional gel electrophoresis. In addition, we plan to test whether the stress, if present, is due to the presence of oxidant (oxygen radicals) by measuring the activity of an antioxidant enzyme (superoxide dismutase).
Vincent Matthews and G. Valentin Borner Ph.D.
Meiosis is the process which forms gametes and spores for reproduction in eukaryotic cells. During the pachytene phase of meiosis I, a protein structure, called the Synaptonemal Complex (SC), forms between homologous chromosomes and creates a scaffold for genetic recombination. In yeast, the Zip1 protein is a major structural component of the SC. At restrictive temperature for meiosis, ZIP1 is required for completion of meiotic divisions. At permissive temperature ZIP1 is required for proper chromosome segregation. We observed that chemical inhibition of the proteasome, with MG132, results in arrest at prophase of meiosis I. Based on these results, we questioned whether there is a regulatory relationship between the SC and the proteasome. Our findings demonstrate the localization of the proteasome along the SC, consistent with proteolysis of SC proteins by the proteasome. Furthermore, lack of double-strand breaks, lack of SC and lack of recombination proteins, result in failed proteasome recruitment to chromosomes during meiosis I. This implies that the proteasome plays not only a role in proper meiotic division, but also double-strand break repair and chromosomal recombination. Fluorescent microscopy techniques were applied to determine the chromosomal localization of the proteasome. Epitope tagged recombination proteins (ZIP1, ZIP3 and MSH4) were utilized along with tagged proteasome components to determine the pattern of proteasome localization to meiotic chromosomes. This is significant as a clearer, fundamental understanding of the proteasome’s role in meiosis may serve to illuminate the causation of many birth-defects, miscarriages and stillbirths.
Atomic Force Microscopic and electrochemical study of polymeric microgels as a prototype for temperature-sensitive drug-releasing carriers
Janna Mino, Justin Flaherty, Pratheek Koneru, and Kiril A. Streletzky Ph.D.
Crosslinked hydroxypropylcellulose (HPC) form unique microgel particles that display reversible temperature-driven volume change with a critical temperature (Tc) right around values of human fever (~39oC). Heating these microgel particles above Tc results in volume contraction upon internal hydrophobic collapse and expulsion of water. HPC is FDA-approved and thus represents a perfect candidate for a drug-releasing carrier in response to systemic temperature change. This summer undergraduate subproject is one part of a cross-disciplinary project between labs of Dr. Bayachou (Chemistry) and Dr. Streletzky (Physics). The overall project uses a combination of light scattering (Streletzky Lab), and atomic force microscopy (AFM) and electrochemistry (Bayachou lab) to study temperature-driven shape changes and uptake/release of therapeutic agents by HPC microgels. In this part of the project, we will present results of investigations by AFM imaging of various HPC microgel particles both in air and in liquid suspensions. Volume contraction of HPC particles as triggered by temperature increases on the AFM stage provides us with the opportunity to monitor particle size changes as a function of temperature. Detailed analysis of shapes and cross-section of features observed by AFM (Bayachou Lab) will be compared and contrasted with independent measurements by dynamic light scattering studies (Streletzky Lab).
Light Scattering and Spectrophotometry Studies of Polymeric Microgels as a Prototype for Temperature-Sensitive Drug-Releasing Carriers
Janna Mino, Justin Flaherty, Pratheek Koneru, and Kiril A. Streletzky Ph.D.
FDA approved Hydroxypropylcellulose (HPC) polymer can be cross-linked to form microgel nanoparticles that undergo a temperature dependent volume phase transition. We studied the structure and dynamics of HPC microgels and HPC polymer that microgels were made from using Dynamic (DLS) and Static Light Scattering (SLS) and Spectrophotometry. Our results determined the transition behavior of the microgels and polymer as temperatures were varied from Troom to well above the critical transition temperature TC~41ºC. The 200-250nm HPC microgels showed a reversible factor of 4-8 volume shrinkage as temperature was brought above TC. This shrinkage is caused by HPC chains becoming more hydrophobic at the TC and aggregating together to diminish water contact. The transition in polymer was found to be sharper than in microgels. Also, above 50ºC, the microgel particles seemingly aggregate with each other, forming larger clusters. In addition to apparent size from DLS, SLS yielded the molecular weight (MW) and shape factor of the microgels. The MW decreased steadily from 20ºC to 40ºC possibly due to microgels losing water, and then increased at 45ºC, and again at 50ºC, possibly due to loose polymer chains fusing into microgel particles. The shape factor ratio ranged from 0.4 to 0.7, consistent with a soft sphere. The light scattering study of microgels was complemented by Atomic Force Microscopy.
Kimberly Moran, Derek Menzies, Anita Isom, and Naohide Yamamoto Ph.D.
Summary: It has recently been shown that older observers (in their 70's) judge distance to a nearby target (up to 12 m away) very accurately, while younger observers (in their 20's) significantly underestimate the same distance. Although this finding has important scientific and practical implications, more research is needed to confirm whether the observed age difference truly reflects improved accuracy in distance judgment. Importantly, it is possible that there is tendency to increasingly overestimate the distance as observers grow older, and the seemingly accurate performance exhibited by the older observers is a mere consequence of canceling the intrinsic underestimation of distance with the age-related overestimation. The present study is being conducted to address this issue by investigating whether distance judgment stays accurate in even older ages (i.e., 80's). If distance judgment is indeed improved in older age, these observers should continue to show accurate performance in the distance judgment task. Additionally, we aim to test middle-aged observers on the same task to uncover the time course of the change in distance perception through adulthood. This will provide an important clue for understanding what underlies the possible age-related improvement of distance perception.