Effects of Lead-Based vs. Lead-Free Low-Frequency, Low-Intensity Ultrasound Devices on VEGF Secretion from Endothelial Cells in a 3D Scaffold

Research has shown that the application of low-frequency, low-intensity ultrasound (LFLI US) accelerates healing processes within cell tissue (Samuels et al., 2013). In one human study, diabetic ulcers closed approximately 3 times faster when treated with ultrasound (Ngo et al., 2019). Beyond wound healing, LFLI US also holds promising potential in areas such as pain management (Gam et al., 1995) (Gehling et al., 2007), nerve stimulation (Gavrilov et al., 1996), and transdermal drug delivery (Sunny et al., 2012).

Piezoceramics like lead zirconate titanate (PZT) are vital to the function of therapeutic ultrasound devices for their ability to generate ultrasound waves via the piezoelectric effect. Consequently, these devices typically contain over 60% lead. Increasing knowledge about the ramifications of lead-containing appliances on human health and the environment has prompted global regulatory actions like the 2003 European Union law on the “Restriction of Hazardous Substances,” which call for a shift away from lead-based medical devices in the near future (EU, 2003).

To evaluate the therapeutic effectiveness of lead-free piezoceramics and explore viable alternatives to traditional lead-based materials, both lead-based and lead-free devices were manufactured and biological testing on human cells was conducted post-ultrasound application. More specifically, this study monitored the secretion of vascular endothelial growth factor (VEGF), a key stimulator of angiogenesis, in human umbilical vein endothelial cells (HUVECs).

A flexural cymbal transducer design, optimized for operation between frequencies of 20 and 100 kHz, guided the manufacturing process (Sunny et al., 2012). Devices consisted of two identical convex brass caps adhered to either side of piezoceramic disks (Ferroperm Piezoceramics), as well as a positive and negative lead.

Brass sheets were manually cut, sanded, and shaped. A PZT-based Pz26 disk was used for lead-based devices, while a sodium bismuth titanate (NBT) Pz12 disk was used for the lead-free. Individual components were fixed in place with bonding epoxy, wires were attached with cold solder, and the entire assembly was potted in polyurethane epoxy (Spurr’s Epoxy). The resonant frequency of each device was determined using a vector network analyzer and Teledyne RESON probe.

Four groups of HUVECs were seeded in a 3D collagen scaffold. Ultrasound was applied to each group for 15 minutes at varying intensities: 50 mW/cm², 100 mW/cm², 150 mW/cm², while one group received no treatment. After a 48- hour incubation period, the conditioned media was collected and an enzyme linked immunosorbent assay (ELISA) was used to quantify VEGF secretion following manufacturer’s (PeproTech) protocol. This procedure was repeated with both lead-based and lead-free transducers. The differences between absorbance values of each sample–collected at 450 nanometers and 605 nanometers–were used to create a standard curve with a four-parameter logistic (4PL) line of best fit, and further calculate VEGF concentrations in pg/mL. Results were analyzed for significant (p<0.05) differences using a one-way ANOVA and Tukey’s post hoc analysis.

There was a significant difference (p<0.05) in VEGF secretion when comparing the varying ultrasound intensities to the control group using lead-based devices. While ultrasound application at any intensity led to higher VEGF concentration than the baseline set by the control group, intensities of 50 and 100 mW/cm² stimulated more VEGF secretion than 150 mW/cm².

Although not significantly different, we observed that lead-free ultrasound devices stimulate the same concentration of VEGF secretion in the 100 mW/cm² group when compared to the control group.

This data suggests that applying therapeutic ultrasound at 50 mW/cm² and 100 mW/cm² is potentially more beneficial than application at 150 mW/cm² in the context of wound healing; HUVECs displayed the greatest increase in VEGF concentration at these intensities with lead-based applicators. In turn, this would lead to increased angiogenesis.

Additionally, these results convey that NBT may be a successful substitute for PZT in ultrasound-generating piezoceramics. It is necessary to repeat a 48-hour ELISA with lead-free applicators to validate this finding, yet lead-free devices nonetheless appear to reproduce similar biological effects in HUVECs as lead-based devices.

Design and Analysis of Energy Recovery Methods for Reduced Aircraft Emissions
Aircraft flights are becoming an increasingly popular mode of transportation. However, their harmful impacts on the environment are a growing concern. To combat this issue, many engineers have worked on developing fully electric aircraft. Although they are much more sustainable, they encounter severe limitations imposed by current battery technologies. One alternative route engineers have taken is the development of energy recovery methods (ERM). These methods reduce the fuel consumption of aircraft without significantly changing their structure and functionality, making them an excellent short-term solution. The goal of this research is to add to the existing pool of ERM and analyze their performance to identify the most successful methods. To do so, we generated CAD models of common aircraft, as well as the new and existing ERM, using SolidWorks. We then tested these models in SolidWorks Flow Simulation to determine the drag force they experience. Lastly, we used MATLAB and Excel to develop a mathematical model that utilizes principles of thermodynamics and kinematics to calculate fuel consumption during a typical flight pattern. So far, the results have shown that the ERM are ineffective; however, this finding is not final as the research is in progress.

Cocomposer: A Generative Approach to Electronic Music

The rapid advancement of hardware and software technologies over the past few decades has significantly influenced the evolution of electronic music, empowering producers to leverage these tools in crafting innovative rhythms, sounds, and patterns. Visual programming languages like Max/MSP have been utilized to create algorithmically generated sprawls that challenge the conventions of rhythm and structure to redefine the definition of music. In this context, this paper introduces Cocomposer, a novel framework and algorithm designed to facilitate the generation of non-deterministic electronic music that diverges from conventional music production paradigms. At its core, Cocomposer utilizes a state-based machine to schedule musical events, enabling users to generate MIDI notes through state transitions defined by the user. These transitions are constructed entirely from scratch, utilizing traditional MIDI note parameters while remaining fully mutable, offering real-time flexibility for the user. By assigning probabilities to state transitions, the framework allows for dynamic progressions from one state to another, accompanied by the playback of user-specified notes. This probabilistic approach creates generated music with an organic and algorithmic quality, as the output evolves in a manner that is both unpredictable and influenced by the user-defined parameters. Consequently, Cocomposer represents a significant step forward in the realm of algorithmic music composition, bridging the gap between structured creativity and emergent musical expression.

Linearizable Instances of the Quadratic Minimum Spanning Tree Problem on 3-Connected Graphs

The quadratic minimum spanning tree problem (QMSTP) is graph-based combinatorial optimization problem that, in general, is notoriously difficult to solve. We study special easily-solvable instances of the QMSTP that are known as linearizable, meaning that the quadratic objective can be equivalently rewritten as linear in a manner that preserves the objective function value of each feasible solution. Previous work has shown that a sufficient condition for linearizability is that the (symmetric) matrix of cost coefficients is a weak sum matrix. This work also showed that this sufficient condition becomes necessary for linearizability when the underlying graph is a complete graph. In our work, we broaden this result by proving that this sufficient linearizability condition is necessary if and only if the QMSTP instance is defined on a 3-connected graph.

Unbiased Characterization and Classification of Coffee

Traditional coffee quality assessment relies on certified sensory specialists, who are not easily accessible and can be subjective. These evaluations can lead to inconsistencies in coffee assessment, making it difficult to achieve reliable and standardized evaluations. The goal of this study is to leverage machine learning to objectively classify brewed coffee by brand, class, and roast level using physicochemical characterization. We studied a total of 144 brewed coffee samples from seven different coffee brands ranging across commodity, specialty, and premium classifications, at varying roast levels. For each sample, we measured: pH, color, turbidity, potassium, and total dissolved solids and manually labeled the brand, class, and roast level. We evaluated support vector machine (SVM), decision tree, and logistic regression models to predict coffee brand, class, and roast level. The SVM performed best with 100% accuracy using 10-fold cross-validation. Our ongoing research explores the use of cyclic voltammetry to analyze electrochemical properties of coffee. This work aims to develop a low-cost electrochemical analysis method to determine distinct characteristics of coffee, providing an objective alternative to traditional sensory evaluation. A screen-printed electrode can detect oxidation peaks of key coffee compounds. Our initial studies are focusing on estimating caffeine concentration. Features of the cyclic voltammetry curve are extracted and used to estimate the caffeine concentration, using High-Performance Liquid Chromatography to measure the ground-truth concentration. Further analysis will extend this approach to include chlorogenic acids, a major class of coffee components, to determine their electrochemical signatures.

Visualizing Polymer Concentration Gradient In Organogels Using Dye

The goal of this research is to develop polymeric gels with varying stiffness within a single sample, which could have practical applications in areas such as customized orthotics. To achieve this, a method was created to visually represent differences in gel stiffness by incorporating a dye that correlates with polymer concentration. Since these dye concentration variations are not visible to the naked eye, UV-Vis spectrophotometry was employed to quantify the dye levels. Using Blue 1 dye, a significant absorbance peak was observed at 634 nm in the UV-Vis spectrum. A calibration curve was established to relate absorbance to dye concentration, confirming adherence to Beer’s Law up to a 1 wt% dye solution. This curve facilitated accurate measurement of unknown dye concentrations in gradient samples. The results demonstrated a strong correlation between the visual appearance of dye gradients and the UV-Vis spectrophotometry data, indicating that the gradient creation method is consistent and reproducible. Additionally, microindentation testing was conducted to measure the elastic modulus across the gel samples. The data showed consistent modulus values that corresponded with the dye concentration gradients, further validating the effectiveness of the preparation method. This work presents a straightforward and reliable technique for visualizing stiffness gradients in polymer gels, supporting future development of materials with tailored mechanical properties for diverse applications.

Exploring Liposome-Chitosan and Liposome-Xanthan Gum Interactions

My work investigates the interactions between liposomes and two polyelectrolytes with opposing charges: chitosan, a polycation, and xanthan gum, a polyanion. The primary objective is to assess liposome stability upon interaction with these polyelectrolytes. To evaluate stability, I utilize dynamic light scattering (DLS), zeta-potential measurements, and a calcein leakage assay via fluorescence spectroscopy. When combining chitosan with a 0.25 mg/mL solution of liposomes, a substantial increase in measured effective diameter was observed from 1 ppm to 10 ppm chitosan. In contrast, xanthan gum does not induce a significant change in effective diameter within the same concentration range. The calcein leakage assay provided additional confirmation for the interaction of liposomes and chitosan and lack thereof for liposomes and xanthan gum. This difference is attributed to the negative zeta-potential surrounding bare liposomes, which facilitates stronger electrostatic interactions with the positively charged chitosan compared to the negatively charged xanthan gum. Additionally, calculation of the number of charged groups per mass of each polyelectrolyte shows that xanthan gum has 2.5 times more charge density than chitosan, further amplifying its charge repulsion with liposomes.

The Development and Implementation of a Mini Drop Tower for Energy Dissipating Tapered Spirals

During mating season, male bighorn sheep establish dominance by forcefully ramming their horns into one another. Due to the unique material properties and geometry of their horns, they can do so while experiencing minimal head trauma. This study investigates the impact properties of a horn-like tapered spiral in comparison to a half-sphere geometry using an experimental drop test system. By analyzing how these biomimetic structures dissipate energy, this research aims to enhance the understanding of their impact mitigation. To maximize recorded oscillations of the tapered spiral model, SolidWorks was used to design 3D printed molds, which were cast in Smooth-On Silicone Mold Star 30 to create silicone models of the horn and half-sphere geometries. A drop test system equipped with a load cell, accelerometer, and two Sony RXO high-speed cameras captured the oscillations and maximum displacements of the silicone models following impact from a weighted drop at three heights. Results indicated increasing displacement values along the X, Y, and Z axes with higher drop heights. These findings highlight the need for further refinement of the drop tower to improve test repeatability and reduced standard deviations. Additionally, the data can be used to validate computational models for the development of energy dissipating spirals for safety applications such as car bumpers and helmets.

Gradient Gel Inserts: Innovative Solutions for Knee Pain Relief

The present research focuses on developing a novel shoe insert made of a gel material featuring a controllable stiffness gradient to improve biomechanical foot alignment, reduce knee joint loading, and alleviate knee pain. The material’s stiffness was adjusted by varying polymer concentration, and compression and indentation testing provided insights into the optimal range of these concentrations. A specialized template was designed to ensure consistent gradient sample production, facilitating repeatable results. Fatigue tests simulated real-life conditions, demonstrating the material’s durability under repeated stress. The findings evidence the feasibility of creating a customizable gel material for shoe inserts, offering a promising solution
for managing knee pain.

Sign2Sign – A First Attempt

At the core of human engagement is communication. While technological advances enable convenient translation for different language speakers to communicate, millions of Deaf, Mute, and Hard-of-Hearing people still face immense hurdles due to the lack of accessible tools to facilitate direct sign language translation. Our project aims to build a Sign2Sign direct immersive translation tool using WebXR that takes input from any accessible camera and produces output in WebXR-supported platforms. This paper presents the preliminary results of direct translation between ten gestures of American and Chinese Sign Languages.