REU/RET Site

Polycaprolactone Scaffolds Decorated with Poly(acrylic acid) Microgels for Tissue Engineering

Revekka Agababaeva, Reem Ulay, Hongjun Wang and Matthew Libera

A longstanding issue with tissue engineering is the prevalence of infection. Once bacteria colonizes an implant site, drastic measures such as removing the implant or even amputation must be taken to remove the infection. The goal is to circumvent infection by preventing it in the first place. The proposed mechanism is a self-defensive scaffold which will release antimicrobials only when bacteria make contact. It will be composed of polyacrylic acid (PAA) microgels deposited on a polycaprolactone (PCL) scaffold and then loaded with antimicrobial agents. The scaffold is meant to mimic the extracellular matrix in order to promote osteoblast adhesion and proliferation. The printing of PCL scaffolds, the loading of PAA gels, and the complexation of the two components were studied. PCL scaffolds were printed on a custom Near Field Electrostatic Printer with the average dimensions being 50 μm fiber diameter and 150 μm interfiber distance. To complex the scaffolds and gels, the scaffolds were treated with oxygen plasma and poly(allylamine hydrochloride), then placed in a microgel solution. To mimic cationic antimicrobial loading, Methylene Blue (MB) and Bismarck Brown (BB), cationic dyes with charges of +1 and +2 respectively, were mixed into separate pH 7.4 buffers. It was found that when a swollen bulk PAA gel was placed into a MB solution, the hydrogel sequestered MB. When the MB swollen gel was placed in a BB buffer solution, the BB displaced the MB and was sequestered in the gel. The results of this study show the phenomena of the sequestration of MB and BB which can be applied to cationic antimicrobial agents complexation with PAA microgels.

Exploring Poly(Ionic Liquid)-Grafted Nanoparticles in Solutions of Organic Solvents and Ionic Liquids

Deniz Bulucu and Pinar Akcora

Solid polymer electrolytes provide effective uses in batteries due to their easy processability and safety, but exhibit limited ionic conductivity. Polymerized ionic liquids (PILs) counter this shortcoming by bearing the reactional groups undergo polymerization, while the counterions (anions) remain freely mobile. The self-assembling nature of iron oxide (Fe3O4) nanoparticles, when grafted with polymer electrolyte chains, further increases ionic conductivity due to enhanced motion of counterions. This research focuses on investigating the conductivity and structural stability of PIL-grafted nanoparticles (PILgNPs) in solutions of ionic liquids (ILs) and organic solvents.

We conducted temperature-dependent electrochemical impedance spectroscopy (EIS) measurements to observe the activation energies of conductivities for ionic liquids (as monomers, oligomers, and PILgNPs) in solutions of both pure dimethylformamide (DMF) and mixtures of DMF and IL (HMIm-TFSI). We examined the dissipation factor (tan) and the frequency of tan peak maximum of each solution to observe the ionic conductivity differences. In addition, we performed transmission electron microscopy (TEM) on our nanoparticles and analyzed particle size distribution and dispersion by using ImageJ. The EIS data showed that ionic conductivity correlates with particle dispersion. Ions move faster in DMF wherein particles are dispersed better. On the other hand, ions move slower in DMF/HMIm-TFSI when particles are aggregated. Our results show that the activation energy is influenced by ion cluster motion and nanoparticle structures, which may provide effective uses in batteries.

Designing Cation-Disordered Rocksalt Materials for Electrochemical Lithium Storage

Eden Chanand Jae Chul Kim

The state-of-the-art cathode material for lithium-ion batteries are lithium transition metal oxides with a layered structure, in which the redox centers are cobalt and nickel. Although many metals form layered structures, only a few metals can retain the layered structure upon deep delithiation [1]. The narrow compositional space of metals that are structurally stable as layered oxides (Co, Ni, and Mn) create resource problems as industry growth needs surpass current productions of these elements. A wider compositional space can be explored using cation-disordered rocksalt (DRX) materials, a structure derived from the layered structure.

Here, new DRX cathodes were designed, in which Ni, Mo, Ti, W, and/or Nb are transition metals, with the usage of nickel limited to a maximum of 40%. The results showed that increasing the calcination time from 2 hours to 4 hours at 900C increased the purity of the material and increased the initial discharge capacity from 80 mAh/g to 89.6 mAh/g for LNTWO20. Increasing the calcination temperature from 750C to 900C for a 2-hour calcination time improved the purity of the DRX material and increased the initial discharge capacity from 101.5 mAh/g to 119.0 mAh/g for LNTNbO20. Lastly, excess lithium content amongst materials that contain the same elements (LNTO/LNTO3) increases the percent of theoretical capacity achieved but does not apply to materials containing different elements; under the same synthesis conditions of 900C and 2-hr firing time and an excess lithium content of 1.5, LNTNbO20 surpassed that of LNTWO20 by a 30% difference in the percent of theoretical capacity achieved.

The Effect of Crosslinker Concentration on the Swelling of Polyethylene glycol (PEG)-based Hydrogels

Casey Dolan and Matthew Libera

The combination of photonic crystals and hydrogels can be engineered to function as a colorimetric sensor for a variety of applications. Hydrogel swelling has the ability to change the lattice spacing and resulting color of a photonic crystal, which is the mechanism that drives a colorimetric sensor. The swelling capability of a hydrogel is an important factor to control in order to create a functioning sensor. The influence of polyethylene glycol diacrylate (PEGDA) weight percentage on the swell ratios of hydrogels was investigated. Polyethylene glycol (PEG) and polyethylene glycol methyl ether methacrylate (PEGMEMA) hydrogels were created with varying amounts of the crosslinking agent, PEGDA. Molds made of polydimethylsiloxane (PDMS) were created to control the dimensions of the resulting gels and allow for efficient production. The swell ratio was calculated for each gel in order to quantify the changes in swell caused by the varying PEGDA weight percentages. To calculate the swell ratio, the gels were placed in deionized water for 24 hours and then weighed. The gels were then dried in a 40°C oven for 24 hours and weighed again. The weight ratio was taken from these values and results in the swell ratio of each hydrogel sample. For both PEG and PEGMEMA gels, increasing the weight percentage of PEGDA decreased the resulting swell ratio. Introducing more PEGDA into the hydrogels caused more crosslinks to occur, which reduced the mesh size. Smaller mesh sizes limit the ability of the individual polymer chains to uncoil to the same lengths they achieve when less crosslinks are present. Controlling the PEGDA concentration within PEG and PEGMEMA gels increases the possibility of fine-tuning the swell ratio to create specific and exact observable color changes in the colorimetric sensor.

Anti-Tumorigenesis Effects of Smad4 Knockout on Colons Within Mice Artificially Inflamed via DSS

Cullen Grady and Ansu Perekatt

Intestinal inflammation associated with various conditions such as Crohn’s disease and ulcerative colitis are correlated to tumorigenesis and fibrosis. When treated with Dextran Sodium Sulphate (DSS), mice display acute inflammation and tissue damage within the epithelial colon tissue. However, mice with a non-expressive Smad4 gene (a tumor suppressor and transcription factor) demonstrate far milder symptoms. To understand the processes behind this, Smad4^IEC-KO (KO) mice’s repair and immune response was analyzed after DSS treatment within the epithelial colon tissue and compared to the DSS treated control group of mice, wild type (WT). Smad4^IEC-KO mice displayed lower concentrations of inflammatory markers as seen in CRP-ELISA and higher amount of anti-inflammatory markers as seen in Western blots, qPCR, and tissue staining. This correlation suggests that the colonic epithelial immune response promotes wound healing rather than tissue scarring or tumor development in Smad4^IEC-KO in comparison to the WT samples aster DSS treatment. Research into various other proteins, genes, and markers is ongoing to gain a complete understanding of the effect of Smad4^IEC-KO.

Advancing Parkinson's Disease Therapeutics with Computational Antibody Engineering

Malcolm Harrison and Pin-Kuang Lai

Parkinson’s Disease (PD) is an idiopathic neurodegenerative disorder with the second-highest prevalence rate behind Alzheimer’s Disease. The pathophysiological hallmarks of PD are both degeneration of dopaminergic neurons in the substantia nigra pars compacta and the inclusion of misfolded alpha-synuclein (α-syn) aggregates known as Lewy bodies. Despite decades of research for potential PD treatments, none have been developed. The development of new therapeutic agents is a time-consuming and expensive process. Computational methods can be used to investigate the properties of drug candidates currently undergoing clinical trials to determine their theoretical efficiency at targeting α-syn. Monoclonal antibodies (mAbs) are biological drugs with high specificity, and Prasinezumab (PRX002) is a mAb currently in Phase II, which targets the C-terminus (AA 118-126) of α-syn. Schrödinger software BioLuminate and PyMol were utilized for structure prediction, protein preparation, and structure reliability reports of the fragment antigen-binding (Fab) region of PRX002 and 34 different conformations of α-syn (PDB ID: 2KKW). Protein-protein docking simulations were performed using PIPER, and 5 of the docking poses were selected based on the best fit. Molecular dynamics simulations were performed on the docked protein structures for 200ns, and hydrogen bonds, electrostatic, and hydrophobic interactions were analyzed using MDAnalysis to determine which residues were interacting and how often. Hydrogen bonds were shown to form frequently between the heavy chain constant determining region of PRX002 and α-syn. The mAb’s developability was determined by calculating the spatial charge map (SCM) score using DeepSCM, displaying the efficiency and developability of this therapeutic agent.

Do Baseline Measurements Relate to Balance Behavior During Walking and Turning?

Jake Stahland Antonia Zaferiou

A real-time optimal motion capture system can record the movement of people while they walk and determine their balance behavior as a result. The purpose of the study is to use this system to investigate the relationship between how people move vs. existing baseline tests. The baseline tests utilized in the study include the Fall Efficacy Scale–International (FES-I), Manual Muscle Tester (MMT), Trail Making Test (TMT-A and TMT-B versions), Mini-Balance Evaluation Systems Test (miniBEST), Dynamic Gait Index (DGI), and Montreal Cognitive Assessment (MOCA).

This study allowed for the development of a framework for baseline and biomechanical measurement comparisons. The hypotheses for trends between cognitive and perception, strength, clinical balance, and composite calculation with biomechanical measurements had a few data instances with statistical significance, but it was mostly not the case. In the future, larger sample sizes will be needed to come to complete conclusions on some data trends. Some of the data trends had a p-value of greater than 0.05 but less than 0.1; if more participants fill in more points on the data tables, the p-value may decrease below 0.05, making the data statistically significant. Future research should also expand the studies from healthy older adults to those with lower scores on baseline exams to fill all aspects of the graph space not filled in by the participants who already came into the study. Another note is that out of the comparisons that returned significant or nearly significant correlation, most of them (7/9) occurred in the turn trials.

Design of Platinum-Based Bimetallic Catalysts for the Conversion of Biowaste to Green Hydrogen

Emily Whitley and Alyssa Hensley

Biorefineries convert biomass feedstocks to renewable fuels and value-added chemicals via a sequence of chemical transformations. Catalysts are used to increase conversion for these processes, but waste production and low yields are a main drawback of commercial viability. The waste produced from biorefineries is a chemically complex mixture of hydrocarbons that has potential to be upgraded to green hydrogen catalytically through aqueous phase reforming (APR). To maximize green hydrogen production, optimal heterogeneous catalysts for APR must prioritize breaking the intermolecular forces between waste molecules that cause competitive adsorption. We hypothesize that by introducing a transition metal promoter into a Pt catalyst surface, the reaction can favor less competitive adsorption geometries and faster conversion of adsorbates. This hypothesis is tested by studying the deprotonation of acetic acid to acetate on PtM(111) (M = Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, W, Re) using density functional theory calculations. The acetic acid surface coverage tested is 1/8 monolayer (1 ML = 1 adsorbate: 1 metal surface atom), and the surface is simulated as PtM(111) containing a single atom replacement of the promoter metal. The effect of the promoter on the adsorption geometry and deprotonation reaction of acetic acid is determined by calculating the adsorption energy. Through comparison of the promoters’ effect on the adsorption energy and preferred reaction, overarching, periodic trends are identified to aid future rational catalyst design and thus increased use of biofuels in industry. Results show that more oxyphilic and heavier promoters have a stronger effect on the deprotonation of acetic acid on the Pt(111) catalyst surface.

Ionic Investigation: Using the cross-linking of sodium alginate hydrogels to introduce ionic bonding

Taisha Bowman

Chemical bonding is an abstract topic that is often difficult for students to conceptualize. However, abstract information feels more accessible and interesting to students when it is geared towards creating their own product under certain parameters (Brockway et al., 2011, 50). This is meant to be an introductory lesson that connects the established concept of ions with the yet to be learned concept of ionic bonding. This lesson focuses on attraction and how attraction can be used to introduce the topic of bonding. It is important that the students are able to integrate the following concepts into their learning: atoms, physical changes, chemical changes, and ions. In future lessons, students will complete this lab three more times. Each time will introduce a new aspect of bonding. The goal for each of the four labs, in order, are as follows: investigating attraction and ionic bonding; investigating ionic bonding and the activity series; investigating the impact of different cations in ionic bonding; creating the ideal gel bead using qualitative and quantitative data from previous investigations. This three day lesson will focus on the first iteration of the lab, investigating attraction and ionic bonding. At the end of this lesson students will be able to understand chemical attraction, chemical stability, and net zero charge in order to expand on the ways that atoms can chemically bond and interact.

You’ve Got the Power! EmPowering Students to Address our Energy Needs by Designing Batteries

Gary DiFilippo

In the past few decades batteries, and the electrochemistry that underpins them, have become more and more relevant to society as personal electronic devices have become more ubiquitous. At the same time, as the world pivots towards a fossil fuel free future, new applications for batteries have emerged along with new challenges. Despite the importance of this technology, the subject is not generally taught in a meaningful and relatable way in high school science. My unit sets out to address this shortfall by engaging students in a lesson that links real world phenomena, experimentation, and cutting edge research. By being able to pique students’ interests with a real world scenario relating to batteries as well as showing them the parts of a battery the topic will become more real and relevant and they will be able to develop a more accurate model for what is going on inside a battery and how all those parts interact with each other. This learning will be accomplished by having students engage in hands-on experimentation, using simulations and modeling, and examining materials and data from a research laboratory. Through this process students will come to understand how the chemistry of a battery works and apply this knowledge to design a novel battery that fulfills certain expectations. At the end of this unit students should be able to model and explain the reduction and oxidation reactions taking place inside a battery and possess the knowledge necessary to evaluate the roles that certain materials may play in batteries in the future.

Conquering Climate Change and Carbon Crimes: Classroom Catalysis

Celine Mileham

Climate change affects us all, and human activities have significantly increased the amount of carbon dioxide in the atmosphere, in part due to the amount of fossil fuels we consume (Climate Change 101 With Bill Nye | National Geographic, 2015). However, alternative sources of energy can be very expensive, and many of us will still need to rely on carbon-based fuel for some time. We want to create carbon-based fuels from biomass, but this process is difficult as there are many by-products that cannot be readily converted into fuel. Catalysts can be used to help increase the efficiency and efficacy of this process, thus allowing us to have carbon-based fuels that are more sustainable. Another big issue is that humans produce more carbon dioxide than is consumed by the biomass on our planet currently. This means that we need to find ways to capture and sequester carbon dioxide so that we can mitigate the amount of carbon that we are emitting. We should consider producing less carbon dioxide emissions, but realistically human activity will not cease to produce carbon dioxide altogether, even if we reduce emissions. Students will explore these concepts through an engineering design challenge, where they are tasked with creating a model of a catalyst surface to remove CO2 from the atmosphere. Students will then explore the effects of CO2 levels rising and what factors affect CO2 levels across the globe. They will then come up with goals for ideal catalysts to achieve one of the two main goals: reducing CO2 in the atmosphere or increasing biofuel production. By the end of the lesson, students should understand why catalysts are used to help generate biofuel and to help capture carbon dioxide from the atmosphere, explain how this connects to climate change, and evaluate the need for catalysts in creating biofuels and carbon capture.

Knocking Out Food Insecurity with Genetic Engineering: An Evaluation of Climate Change Adaptations on Agriculture

Angela Calasso

With the global population significantly increasing and crop production decreasing, the issue of food insecurity lingers in our future. The main source of food for the world population is agriculture. Around 70-80% of the world’s food comes from family farms that are threatened by the effects of climate change. Gene editing provides a solution to this problem by modifying plant traits to adapt to climate change. These modifications are a result of a knockout of one or many genes that inhibit or change the gene’s normal function. Advantageous modifications include abiotic stress tolerance, increased yield percentage, drought tolerance, insect and pathogen resistance, and prolonged shelf-life. In this three-dimensional, engineering-design lesson, students will be evaluating the knockout effect of ten genes and determining which two provide the most advantageous traits for adapting to climate change. The gene knockout mechanism performed in Dr. Ansu Perekatt’s lab inspired this lesson.

Improving of Lithium Iron Phosphate Batteries by Replacing 65% Iron Atoms with Manganese

Hannah Levy and Jae Chul Kim

Lithium-ion batteries are an important aspect for the energy storage systems already found in fields such as portable electronics and electric vehicles. The most popular materials for lithium-ion battery cathodes are cobalt and nickel, however these metals are expensive as they have become less abundant. Lithium iron phosphate(LFP) cathodes are becoming a more competitive replacement because they have comparable rate capabilities to the cobalt and nickel-based cathodes for a significantly lower price. However, LFP batteries operate in a lower voltage domain, 3.4V, which decreases their energy density and makes them less desirable for commercial application. Manganese has a redox potential of 4.1 V. Replacing 65% of the Iron atoms in LFP cathodes with Manganese ensures that 65% of the Lithium Iron Manganese Phosphate(LFMP) battery’s capacity becomes available in the high-voltage domain. The 65% replacement material reached an energy density of 658 W.h.kg-1, while LFP batteries only reach a theoretical energy density of 580 W.h.kg-1. Our LFMP battery can store 13.4% more energy than theoretical LFP batteries. As the push for phasing out gas and diesel power vehicles grows, it is important that an energy dense and cost efficient lithium ion battery become commercially available. LFMP batteries show great promise to be further adopted by the electric vehicle field because they can store more energy than LFP batteries.

Testing the Understandability of Real-Time Optical Motion Capture Balance Sonification Systems

Vibha Iyer, Mitchell Tillman, and Antonia Zaferiou

Sonification, which conveys information about movement through computer-generated sounds, can be harnessed in order to improve balance in everyday movements [1]. We propose to test the understandability of the current sonification designs in dynamic balance tasks with young healthy adults. Five participants (two male; age 20.4 ± 1.4 yrs) participated in three phases of this study: (1) assessment of prior understanding of balance metrics and sound, (2) familiarization period with the sonification designs, and (3) assessment of understanding of sonification designs. Sonification designs were introduced in a randomized order. Participant design feedback was obtained after each step and the end of the entire study. Four participants were visually observed to generate the correct movements and sounds for the Hf design. Those unable to misunderstood the frontal plane and had concerns about the sensitivity of the system. Three participants were visually observed to generate the correct movements and sounds for the LD design. Those unable to had issues perceiving changes in the biofeedback and described the system as “hard to control”. Those who were introduced to the Hf design first expressed more frustration about being unable to hear the LD sound design, indicating that the order effect could impact one’s ability to perceive changes in sound. Results indicate that further familiarization and increased demonstration of the system would improve understanding. Future work is planned to test if participants can integrate the sounds to change movement execution and expand these studies to older adults during dynamic balance tasks.

[1] Effenberg, A. O. (2005). Movement sonification: Effects on perception and action. IEEE Multimed. 12, 53–59. doi: 10.1109/MMUL.2005.31

Role of Collagen in the Repair Response Following Damage to the Intestinal Epithelium

Cindy Lin and Ansu Perekatt

The aim of this study was to determine the basis for the attenuated response to inflammation in a mouse model of intestinal inflammation. The inflammation is induced by feeding mice with Dextran Sodium Sulfate (DSS). DSS is an irritant and causes erosions in the epithelium, eventually causing bleeding and inflammation. We found that one of the genetically modified mouse models is refractory to the inflammation caused by DSS. This mouse lacks a tumor suppressor protein called Smad4. To determine the cause, we compared the gene expression in normal mice treated with DSS (WTDSS) with mice lacking Smad4, or Smad4 KO mice. We performed bioinformatic analysis using Ingenuity Pathway Analysis (IPA), Gene Set Enrichment Analysis (GSEA), and histological staining. GSEA analysis on the RNA-expression showed increase in genes regulating extracellular matrix (ECM) proteins (the cementing materials around cells) including collagen. This result is confirmed by histological staining. IPA analysis also shows increase in collagen signaling within the wound healing signaling pathway, hepatic fibrosis signaling pathway, pulmonary fibrosis idiopathic signaling pathway, and an enrichment of Wnt signaling pathway. Collagen is a protein molecule composed of amino acids providing support to the connective tissues in the extracellular matrix. Over 90% of the collagen found in the body are type I collagen, making it the most abundant out of all the different types of collagen. Type IV and VI are the two major types that are found at the base of the intestinal epithelial cells. Important roles of collagen include cell growth, differentiation, cellular communication and cellular migration.

Design of a Sliding Cap for the Wind Tunnel at Stevens

Nicholas Marchuk and Nick Parziale

This project designed and built an internal cap for the reflected shock tunnel at Stevens. During tests of the tunnel, metal shrapnel flies through the tunnel at high speed, and a cap that seals against the test section of the tunnel is needed. The design was first modeled in Solidworks, based on a piece of 7.5-inch diameter aluminum stock. It has four through-holes for shoulder screws, for the cap to slide on. The design of the part that it seals against was modified to accommodate these screws. A layer of neoprene was epoxied to one side of the cap to provide an airtight seal. The resulting design fit in the tunnel well and slid along the screws as expected, however there were concerns that the cap might block airflow in the tunnel before the time of sealing. To alleviate this, the design was modified by cutting four corners out of the cap, large enough to allow airflow but not so small as to break the seal against the test section of the tunnel. Unfortunately, the cap was not able to be tested, due to unforeseeable difficulties with the tunnel’s operation. However, the final design is ready for testing, and can be changed quickly if necessary.

Appearance of White Matter Hyperintensities in the Healthy Aging Brain

Grace McGraw and Johannes Weickenmeier

This study explores the role of the septum pellucidum on the spatial distribution of the lateral ventricular wall’s mechanical loading. This anatomical region of the brain is of particular importance in the formation of periventricular white matter hyperintensities which are age-related lesions associated with white matter degeneration and associated with cognitive decline. The septum pellucidum is a thin membrane that separates the lateral ventricle into two distinct compartments. Here, we build a computational model to simulate the effect of the septum on the distribution of mechanical loads along with the wall to identify locations where ependymal cell disruption and subsequent white matter degeneration are likely to occur during aging. We use Simpleware ScanIP to convert a magnetic resonance image (MRI) to a 3D finite element brain model. We import the meshes into the simulation software Abaqus and simulate various loading and boundary conditions. The anatomical features included in the model were the septum pellucidum, cerebrospinal fluid (CSF), gray matter, white matter, and the lateral ventricle. For modeling reasons, we assume an axisymmetric brain model; we apply a surface pressure on the inside of the ventricular wall to mimic hemodynamic loading. We record wall displacement magnitudes and displacements in the lateral brain directions are mapped. We concluded that the appearance of these periventricular white matter hyperintensities occur due to the high loading, stretches and strains of ependymal cell. The septum impacts cell loading by adding an extra stretch and strain along the periventricular wall, which increases the appearance of white matter hyperintensities.

Characterizing the Nanoscale Surface Behavior of Multifaceted Ni-Based Bimetallic Catalysts Using Density Functional Theory

Thomas E. Robinson and Alyssa J.R. Hensley

The use of fossil fuels as a source of energy causes a release of carbon emissions, typically in the form of CO2, to the atmosphere. Biofuels are a carbon neutral alternative and can be catalytically synthesized from biomass through deoxygenation reactions. However, chemical complexities in biomass feedstocks create challenges within catalysis because they exhibit significant non-uniformity. Ni-based bimetallic catalysts have shown a strong affinity for the synthesis of biofuels.[1] Critically, the structure and surface composition of bimetallic catalysts can drastically change under reaction conditions, with the computational prediction of such behavior potentially leading to significant advances in catalyst design.

Here, we use density functional theory to characterize the adsorption of H*, O*, and OH* across Ni-based bimetallic surfaces to determine the interplay between the surface chemical potential of hydrogen and oxygen and the working catalyst surface structure. Three distinct surface facets, i.e. (111), (110), and (100), are examined (Fig. 1a). In addition to pure Ni, several bimetallic combinations are constructed, where Ni is the host metal, and Au, Co, Cu, Mo, Re, Ru, and W, are the promoters with a concentration of ~6%. Furthermore, the constructed Ni-based catalysts are compared to both pure Pt and Pt-based bimetallic catalysts (Fig. 1b). For example, the O* and OH* adsorption energies for pure Ni are lower than pure Pt by 1.18 eV and 1.45 eV respectively. Furthermore, the addition of oxophilic metal W to pure Pt lowers the adsorption energy of O* and OH* by 1.41 eV and 0.63 eV compared to pure Pt, indicating a more thermodynamically stable configuration and suggesting stronger driving forces for high surface oxygen chemical potential. Changing the surface properties from the addition of a promoter can be applied systematically to modify the adsorption characteristics of pure metal surfaces. By combining the DFT results obtained on three distinct facets with kubic harmonic interpolation [2], we can capture the equilibrium surface coverages of H*, O*, and OH* over a single, multifaceted catalytic nanoparticle. Distinct regions of the nanoparticle represent different surface facets of the catalyst. An example is shown in Fig. 1c, where O* displays the highest coverage on the (111) facet and low coverage on the (100) and (110) facets. At a nanoparticle scale, the DFT calculations can depict the working catalytic surface for various H2 and O2 pressures and temperatures with molecular fragments of H*, O*, and OH*. This work highlights and provides a foundational basis for expanding into full surface reactions, potentially enabling the rapid identification of advantageous bimetallic catalysts for biofuel production.

1. M.M. Ambursa, et al., A review on catalytic hydrodeoxygenation of lignin to transportation fuels by using nickel-based catalysts, Renewable and Sustainable Energy Reviews, 138 (2021)
2. J. Bray, et al., Modeling the adsorbate coverage distribution over a multi-faceted catalytic grain in the presence of an electric field: O/Fe from first principles. Catalysis Today, 312, Pages 92-104, (2018)

Understanding Environmental Interactions of Poly(acrylic acid) Grafted Silica in Water

Seena Seon and Pinar Akcora

Polymer-grafted nanoparticles are used for numerous applications as they provide tunable properties based on their self-assembled nanostructures. Grafting pH-responsive polymers, such as poly(acrylic acid) (PAA), on silica nanoparticles allows for controlled particle-particle interactions, dispersion, and entanglement states, all dependent on pH. This study focuses on synthesis of PAA-grafted chains on silica (SiO2) nanoparticles, where properties dependent on many-body interactions are investigated using Thermogravimetric Analyzer (TGA), Fourier Transform Infrared (FTIR) Spectrometer, a rheometer, and a Zetasizer. The determined properties provide insight on the molecular weight, polydispersity index, graft density as well as the viscosity, detectable ionic groups, and stability with respect to the pH of the grafted entities. A weak polyelectrolyte, PAA is chosen for this study to understand how long grafted chains influence viscosity and stability of particle suspensions by altering the pH. Potential applications for polyelectrolyte-grafted nanoparticles are water treatment membranes, gel electrophoresis, protein separation and drug delivery.

Synthesis of Rare Organoboron Compounds via a Novel Boron-Promoted Conjugate Addition Reaction

Mahein Shah and Abhishek Sharma

Organoboron chemistry is composed of a diverse set of compounds that are used broadly in various fields of chemistry, ranging from organic synthesis to pharmaceuticals. Geminal diborons have recently emerged as flexible building blocks for the formation of structurally complex organic compounds that serve many applications ranging from the production of synthetically useful γ-borylate ketones to applications in the field of biomedicine. However, current methods often involve the deborylation of geminal di-/triboryl alkanes or require additional activating groups. Deborylation is not optimal because the removal of a carbon-boron bond can reduce the flexibility of the organic compound and therefore reduce its effectiveness. Boron promoted conjugate addition reactions are underexplored and have many benefits in the field of geminal diboryl alkanes. This study avoids these pitfalls and rather focuses on synthesizing rare organoboronates via deprotonation, allowing one-pot conjugate addition−oxidation that activates the geminal diboron as soft pronucleophiles. This provides the crucial 1,4-dicarbonyl frameworks, confirmed by HNMR spectroscopy, which are common motifs in numerous natural products and pharmaceutical agents.

Modeling anode geometry to suppress dendrite growth in lithium-metal batteries

Alexa Babick (Northeastern University), Lauren Chew

Advisor: Jae Chul Kim

This study aims to address the issue of dendrite growth in lithium-metal batteries by altering the surface morphology of the lithium anode. Similar to lithium-ion batteries, lithium-metal batteries replace the typically graphitic anode with solid lithium, resulting in drastically improved capacity and energy density. However, lithium-ions will accumulate on the metal anode, leading to the formation of branched structures, known as dendrites. The formation of dendrites creates a serious issue, as the battery short circuits if dendrite growth reaches the cathode. Various surface geometries were tested using the COMSOL Multiphysics software and the accompanying Electrodeposition module to simulate lithium-ion accumulation. Specifically, the Nernst-Planck equation and Butler-Volmer equation were used to model the movement and deposition of the ions. The results showed that a highly tapered geometry increases the surface area exposed for deposition, while a thin stem on top directs the accumulation downwards in a triangular shape. These qualities aided in reducing dendritic growth towards the cathode, even at increasing electric potentials. Therefore, in simulation, the altered anode morphology was able to successfully suppress undesired dendrite growth in lithium-metal batteries, increasing their viability for use as high-performance batteries.

Biomechanics of whole-body angular momentum and balance state

Kayla Eng (County College of Morris)

Advisor: Antonia Zaferiou

Falls occur because there is a loss of balance. Perturbations, medical conditions, and age make people susceptible to falls. Sometimes people redirect a potential fall by catching themselves. However, certain populations are less likely to do so. The most vulnerable population is older adults as one in four U.S. residents aged ≥65 years reports falling each year. This study uses a deliberate forward lunge to mimic the movement when a person leans forward too far and extends a foot out, thus catching oneself and preventing a fall. Comparing whole-body angular momentum before and after the total body center of mass leaves the base of support assesses the state of balance and unbalance. It is hypothesized that when the center of mass is outside the base of support, the whole-body angular momentum is greater than when the center of mass is in the base of support. An Optical Motion Capture system, Mokka, and Microsoft Excel were used to calculate the total body center of mass, base of support, angular velocity, moment of inertia, and whole-body angular momentum. The whole-body angular momentum calculations were treated as though the body was a rigid body, specifically a cylinder. The results supported the hypothesis. When the total body center of mass was outside the base of support, the average whole-body angular momentum was 0.031 m/s, greater than when the total body center of mass was in the base of support, 0.012 m/s. As a note, this study used one trial and one subject. To further explore this area, more trials and subjects are needed.

Validating 3D brain simulations of white matter hyperintensity formation using amplified magnetic resonance imaging

Madison Grigg (West Virginia University)

Advisor: Johannes Weickenmeier

Amplified magnetic resonance imaging (aMRI) is a new imaging method that allows for visualization of brain movement due to hemodynamic forces. aMRI can be used to quantify the deformation of the lateral ventricles during a single heartbeat with the goal being to determine maximum loading of the surrounding tissue. The respective displacement data, collected from aMRI data, of the ventricular wall is used to validate numerical simulations of brain tissue at peak hemodynamic pressure. These simulations mimic the cyclic loading of ependymal cells (the cells lining the lateral ventricular wall) during each heartbeat and are used to rationalize the onset location of periventricular white matter hyperintensities (pWMHs). pWMHs are white matter lesions that appear in the aging brain and result from tissue damage due to a combination of lack of nutrients to the surrounding tissue, as well as degradation of the ependymal wall. Our simulations show that increased hemodynamic pressure leads to increased cell loading and is a driving factor in the onset of pWMHs in the aging brain.

Ion transport on cellulose nanocrystal in ionic liquid-based electrolyte

Mika Naseef (Stevens Institute of Technology)

Advisor: Pinar Akcora

Ion transport in liquid electrolytes depends on the viscosity, ion diffusivity, ion concentration, ion size, and the charge of solutions. In this study, we tested how charged fillers influence the ionic conductivity of ionic liquid (IL)-based electrolytes. By mixing Cellulose Nanocrystal (CNC) fillers with 1-Hexyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide (HMIM-TFSI), stable suspensions at different concentrations are successfully prepared and characterized in Electrochemical Impedance Spectroscopy (EIS), Fourier-Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). Ion conductivity measured by analyzing the Nyquist plots for CNCs in water and HMIM-TFSI at different concentrations are compared. Ionic conductivity is calculated using a phenomenological equation that relates ionic conductivity to the resistance and reactance derived from EIS. We hypothesized that the sulfate groups that reside on the surface of CNC resulting from sulfuric acid hydrolysis would interact with the cation (HMIM+) of the IL. Thus, there will be free TFSI- anions contributing to the higher conductivity measurements. Furthermore, the addition of CNC to an IL would enhance viscosity as well as conductivity and provide mechanical support. These features will affect the ion distribution and will enhance ion transport across the fuel cell electrolyte. Our experimental results show that conductivity of water increases with CNC concentration up to 5 wt%, and IL conductivity is measured to be the highest with 2 wt% CNC. The higher CNC concentrations did not perform as well in IL, suggesting that the viscosity of the system could be inhibiting the transport. CNC/IL hybrid electrolytes can potentially find interesting applications in batteries for suppressing the dendrite growth as well as enhancing the thermal stability of electrolytes.

Cal-Tech T-5 hypervelocity shock tunnel converging-diverging nozzle design

Andrew Sayad (Fairleigh Dickinson University)

Advisor: Nick Parziale

Research and design processes are presented for the converging-diverging nozzle of the T-5 hypervelocity free-piston driven reflected-shock tunnel at the California Institute of Technology. The purpose of this design study was to develop a nozzle that would minimize the disturbances in the freestream and reduce the effects of shock and standing waves in the tunnel. The initial nozzle design was done by a joint group of WBM, Stalker, and Bechtel engineering consultants, which included the mechanical drawings and relevant information of the design. A preliminary Computational Fluid Dynamics (CFD) simulation was conducted on the Solidworks model using the flow simulation Solidworks add-in. The simulation was run on the original model to confirm the need for a redesign. The dimensions of the model were then checked, using the various Solidworks measuring tools, and then cross referenced with the mechanical drawings. Dimensional discrepancies involving multiple parts of the assembly were documented. The dimensions were then corrected using the Solidworks sketch function and new part models were created. The new models allow for a better assembly fitment and better consistency with the mechanical drawings. This design process is ongoing and the work that has been presented in this poster has shown the need for revisions in the nozzles original design. The redesign of this nozzle will allow for greater experimental accuracy and capabilities in hypersonic flow experiments.

Polymer design with various functional groups with a focus on microplastics

Alexandros Pavlou (The Cooper Unio)

Advisor: Patricia Muisener

“Seeing” atoms with atomic force microscopy (AFM): a 5E lesson plan for high school chemistry

Jamie Kubiak, Chemistry Teacher, Park East High School, NY

How do we know what we know about atoms when we cannot see them? In a typical high school chemistry class, this fundamental question is not addressed. This lesson plan makes a connection between nanoscale research happening and the high school chemistry curriculum while attempting to fill a gap by making it more phenomena-based in order to align with NGSS standards. Often, a 9-12 chemistry class focuses on what’s inside an atom (protons, neutrons, electrons) but doesn’t help students understand how we “see” atoms, even though they are so much smaller than the wavelengths of visible light. Of course, we can’t see atoms, even with more powerful microscope lenses, so scientists use a number of methods for probing what atoms “look” like, including atomic force microscopy (AFM). This 5E lesson plan for high school chemistry classes encourages students to engage and grapple with the idea that we cannot see atoms, but we can still gather information about their shape, their forces of interaction, and their properties. They start by engaging with the sizes of nanoscopic/microscopic structures, use a black box model of AFM to explore the structure of a mystery item, learn about how AFM works through video and reading explanations, elaborate on their understanding by applying it to viewing bonding in molecules, and end with evaluating their learning with a Claim, Evidence, and Reasoning framework assessment. This lesson plan was developed with support by the National Science Foundation, REU/RITE Site program Grant No. 2050921 through Stevens Institute of Technology in New Jersey.

Mini-unit: exploring mechanical properties of polymers

Ikechukwu Onyema, Chemistry Teacher, East Orange Campus High School, NJ

How can secondary chemistry educators improve student understandings of how changes at the molecular level influence material properties while enhancing student engagement? How can educators develop students’ abilities to communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials? The following mini-unit, “Exploring Mechanical Properties of Polymers,” is designed to fill a gap in the high school chemistry curriculum by making it more phenomena-based and Next Generation Science Standards (NGSS) aligned. Using computer simulations, students will be able to formulate chains of repeating monomers and contrast their behavior in the presence of a crosslinker. Next, students will investigate why some plastics are recyclable while others aren’t by contrasting the molecular differences between polymers. Finally, students will carry out the Viscoelasticity by Design Inquiry Lab which will give students the opportunity to design a procedure to optimize design for various material properties such as ‘highest bounce’ or ‘longest stretch.’ Upon completion of this unit, students will be able to distinguish between natural and synthetic polymers and appreciate how chemists change the properties of materials for use in different products by changing molecular structure.