Biomedical Engineering and Bioengineering Commons^™

A New Electroencephalography Electrode Design For Curly And Kinky Hair Types, Elena Butler

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Medical discrimination and implicit bias are present in both societal systems and into the design and validation of medical devices. Traditional electroencephalography (EEG) systems often fail to provide reliable physiological recordings on curly and kinky hair types (3B–4C), associated typically with Black American and others of African descent. EEG on these hair types often results in high electrode-scalp impedance, poor signal quality, and participant discomfort. Consequently, such technical biases contribute to the underrepresentation of these populations in neuroscience research and clinical diagnostics, while simultaneously limiting equitable access to EEG-based medical care.

To address this gap, a novel conductive electrode attachment …

Beyond Local Pathology: Exploring The Role Of Gut Microbiota In Chronic Low Back Pain Using An Integrated Behavioral And Microbiological Approach, Adan L. Redwine

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Chronic low back pain (LBP) affects millions worldwide, often originating from intervertebral disc (IVD) degeneration. While the gut microbiome modulates musculoskeletal pain, prior studies of the gut-disc axis have focused entirely on structural changes. This leaves a critical gap: does the microbiome influence the experience of discogenic pain? To answer this, an integrated approach using longitudinal gut microbiome profiling, machine learning-based behavioral phenotyping, and structural disc assessments in a rat model of discogenic LBP was utilized.

Female Sprague Dawley rats underwent one of four conditions: sham surgery, IVD injury, antibiotic-mediated microbiome depletion + IVD injury, or IVD injury + treatment …

Preclinical Animal Modeling To Investigate Redox-Mediated Molecular Dysfunction In Traumatic Brain Injury, Brandon Z. Mcdonald

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Impacts associated with traumatic brain injury (TBI) induce a multitude of neurological morbidities mediated by a spread of biochemical dysfunction. Redox stress is a significant contributor to TBI pathophysiology and several redox stress markers have substantial evidence to support their role in diagnosing preclinical and clinical TBI. However, there is a critical need to verify their translational utility through correlations with behavioral, imaging, and molecular modalities. In chapter two, we examined the therapeutic efficacy of an antioxidant treatment (NPC3) using a controlled cortical impact (CCI) mouse model of TBI. NPC3 alleviated glial expression and reactivity while influencing the expression of …

A Webcam Eye Tracking Infrastructure For Software Engineering Tasks, Zachary M. Kozak

School of Computing: Dissertations, Theses, and Student Research

Performing eye tracking utilizing commodity webcams has been explored for over a decade, but limited camera quality and sensitivity to head movements have hindered its adoption in research settings. Recent advances in consumer-grade webcams and machine learning methods present an opportunity to improve the accuracy of webcam eye tracking and extend the feasibility of studies beyond controlled laboratory environments.

Current popular webcam eye tracking methods restrict implementations to the browser and rely on continuous user interactions for calibration, limiting the kinds of studies that can be conducted. This thesis presents a feature-based gaze prediction system that incorporates eye geometry and …

Teachers Of Students With Visual Impairments (Tsvis) Assistive Technology (At) Competencies: An Update Study, Benjamin Kendall Lytle

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Assistive technology (AT) is essential for supporting access, independence, and learning among students with visual impairments. Teachers of students with visual impairments (TSVIs) are expected to integrate AT into instruction and ensure their students are prepared for academic, social, and workforce demands. The original list of 111 AT competencies for preservice TSVIs, developed by Smith et al. (2009), provided an important foundation but has not been revised despite significant technological advances over the past decade. Outdated competencies risk limiting teacher preparation programs and leaving educators underprepared to address the realities of today’s classrooms. A revised and streamlined competency framework is …

Synthesis And Study Of Stable Organic Radicals For Mri Contrast Agents And New Materials, Sabina Dhakal

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The first part of this dissertation focuses on the design, synthesis, and characterization of a thermally robust S =1/2 phototetrazolinyl monoradical and the development of synthetic methodologies for a high-spin (S = 1) phototetrazolinyl diradical. Electrochemical studies of the phototetrazolium cation (precursor to the monoradical) revealed a remarkably narrow electrochemical band gap (Ecell ≈ 0.82 V), suggesting promising electrical conductivity. Thermal analysis of the monoradical demonstrated excellent stability, with the onset of decomposition at 232 °C. Building on the excellent thermal stability and promising properties for electrical conductivity of the monoradical, we developed two condensation-based synthetic routes that provide viable …

Developing A Metabolic Engineering Chassis From A Metabolically Versatile Organism, Rhodopseudomonas Palustris Cga009, Mark William Kathol

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Metabolic engineering has made it possible to develop biological processes that were once considered economically unfeasible or uncompetitive. This field has enabled both a robust niche market, whereby products, such as pharmaceutical substances like monoclonal antibodies, are produced exclusively through biological means, as well as an emerging commodity production market. Nonetheless, significant challenges remain in harnessing the unique metabolic capabilities of genetically non-tractable organisms. This dissertation focuses on Rhodopseudomonas palustris CGA009 as a potential chassis for metabolic engineering. To address the issue of genetic intractability, a synthetic biology toolkit was developed to facilitate the expression of heterologous proteins in R …

Next-Generation Biomedical Implants And Stimuli Responsive Soft Optical Arrays Via Surface Functionalized Elastomeric Materials, John M. Kapitan

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The demands of emerging technologies, such as soft robotics, stretchable electronics, and next generation biomedical implants, has led to the development of diverse polymeric and hybrid organic/inorganic materials specifically tuned to meet these challenges. These materials typically have low Young’s moduli and are inert with high chemical stability. However, this has led to materials that are static in nature, lacking any meaningful way of responding to changes in their environment and adapting to these changes. This has driven a shift towards the design, manufacturing, and characterization of various stimuli responsive surfaces, relying on precise control of surface chemical coatings and …

Evaluation Of Gfap And Ptau Protein Expression In Male And Female Cci Mouse Models, Sara Wallace

Honors Program: Senior Projects (Public)

Traumatic Brain Injury (TBI) is a serious public health concern that leads to the death or disability of thousands of individuals in the US annually. Progression of TBI involves primary damage from the initial, mechanical injury and secondary damage, from nonmechanical, pathological dysfunction. The secondary damage mechanisms can be better understood, diagnosed, and treated through the quantification of TBI biomarkers. The two biomarkers of interest in this study are pTau and GFAP. The male and female mouse models showed similar significant increase in GFAP following injury, as well as a general lack of increase in pTau expression following the injury. …

Inactivation Of Zika Virus With Hydroxypropyl-Beta-Cyclodextrin, Cory R. Hewitt, Nicholas J. Wixon, Arthur Gallegos, You Zhou, Victor C. Huber, M. Scott. Killian

Nebraska Center for Biotechnology: Faculty and Staff Publications

Background/Objectives: Zika virus (ZIKV) infection is associated with life-threatening diseases in humans. To date, there are no available FDA-approved therapies or vaccines for the specific treatment or prevention of ZIKV infection. Variation in the ZIKV envelope protein (Env), along with its complex quaternary structure, presents challenges to synthetic approaches for developing an effective vaccine and broadly neutralizing antibodies (bnAbs). We hypothesized that beta-cyclodextrin (BCD) could be used to uniquely inactivate infectious ZIKV without disruption of Env.

Methods: ZIKV was propagated in Vero cells and admixed with BCD. The BCD-treated ZIKV was evaluated for infectivity using immunofluorescence and quantitative …

Characterization Of Multispecies Microbial Communities At Beef And Pork Processing Plants And Their Impact On Pathogen Stress Tolerance, Rong Wang, Sapna Chitlapilly Dass, Vignesh Palanisamy, You Zhou, Tatum Katz, Joseph M. Bosilevac

Nebraska Center for Biotechnology: Faculty and Staff Publications

Escherichia coli O157:H7 and Salmonella enterica are major foodborne pathogens. Biofilm formation may potentially contribute to product contamination by these pathogens at meat processing facilities. Further, pathogen stress tolerance may vary significantly due to the interactions with the multispecies microbial community at meat plants, which may be affected by processing activity, animal species, and the local selective pressure caused by sanitization practices.

We characterized natural microorganisms collected from floor drains at various areas at three beef plants and two pork plants and analyzed their impact on pathogen sanitizer tolerance.

The pathogen strains were able to integrate efficiently into the multispecies …

Robust Quantification Of Cortical Hemodynamic Response To Tactile Stimulation: A Comprehensive Fnirs Methodology To Mitigate Physiological Confounds, Mohsen Hozan

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation establishes a quantitative framework for studying somatosensory processing using functional Near-Infrared Spectroscopy (fNIRS), with a focus on applications in neurorehabilitation. The central aim is to investigate how the brain's hemodynamic response is modulated by the velocity of patterned tactile stimulation. While fNIRS is a promising neuroimaging tool, its data quality is often compromised by physiological noise and motion artifacts, challenging the reliability of its findings and hindering the development of effective, quantifiable neurotherapeutics.

Two preliminary investigations informed the final experimental design. The first pilot study confirmed that pneumotactile stimulation of the hand, during both passive (somatosensory) and active …

Microscopic Analysis Of Temperature Effects On Surface Colonization And Biofilm Morphology Of Salmonella Enterica, Zachariah Vice, You Zhou, Sapna Chitlapilly Dass, Rong Wang

Nebraska Center for Biotechnology: Faculty and Staff Publications

Salmonella enterica represents a diverse group of pathogens commonly associated with food contamination including red meat. Even though pre- and post-harvest cleaning and sanitization procedures are widely implemented at meat processing plants to mitigate the hazard, S. enterica cells may escape the process by colonizing, on contact, surfaces in the form of a biofilm that functions as an aggregated microbial community to facilitate mutual protection, antimicrobial resistance, proliferation and dissemination. Biofilm development is a complex process that can be affected by a variety of factors including environmental temperature. We developed methods using scanning electron microscopy and confocal microscopy with a …

Assessing Reproducibility Challenges In Clinical Metabolics, Darcy Lin Cochran

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Current metabolomics research is expanding to be multiplatform and interdisciplinary. Metabolomic analysis has the potential to provide detailed insight into any biological system of interest to analyze the underlying molecular mechanisms of variables like environment, disease, and genetics. Human clinical metabolomics is a major research area that is often focused on finding biomarkers or panels of biomarkers for different diseases. However, results are difficult to compare across different laboratories since the field of metabolomics has yet to widely adopt best practices for sample preparation, data acquisition and data processing, results are difficult to compare across different laboratories.

This thesis focuses …

Aphid-Ant Relationships: The Role Of Cuticular Hydrocarbons And Different Chemical Stimuli In Triggeringmutualistic Behavior, Amged El-Harairy, Ahmed El-Harairy, Alaa Mahfouz

Department of Chemical and Biomolecular Engineering: Faculty Publications

In ant-aphid interactions, various aphid species offer honeydew to the ant partner and increase their density by ant attendance, whilst others never attend ant species, in which case ants tend to treat them as prey. In this regard, ants should have the ability to distinguish myrmecophile aphid species from non-mutualistic species, so that mutualistic aphids will be accepted as partners rather than prey. Although ant-aphid interactions are now the focus of chemical ecology studies, the role of the different chemical stimuli in determining mutualistic interactions has not been completely clarified. Therefore, we have investigated the cuticular hydrocarbon profile of four …

Influence Of Alkali Metal Cations On The Oxygen Reduction Activity Of Pt5Y And Pt5Gd Alloys, Kun-Ting Song, Alexandra Zagalskaya, Christian M. Schott, Peter M. Schneider, Batyr Garlyyev, Vitaly Alexandrov, Aliaksandr S. Bandarenka

Department of Chemical and Biomolecular Engineering: Faculty Publications

Electrolyte species can significantly influence the electrocatalytic performance. In this work, we investigate the impact of alkali metal cations on the oxygen reduction reaction (ORR) on active Pt₅Gd and Pt₅Y polycrystalline electrodes. Due to the strain effects, Pt alloys exhibit a higher kinetic current density of ORR than pure Pt electrodes in acidic media. In alkaline solutions, the kinetic current density of ORR for Pt alloys decreases linearly with the decreasing hydration energy in the order of Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺, whereas Pt shows the opposite trend. To gain …

A Review Of Proton Exchange Membrane Degradation Pathways, Mechanisms, And Mitigation Strategies In A Fuel Cell, Dharmjeet Madhav, Junru Wang, Rajesh Keloth, Jorben Mus, Frank Buysschaert, Veerle Vandeginste

Department of Chemical and Biomolecular Engineering: Faculty Publications

Proton exchange membrane fuel cells (PEMFCs) have the potential to tackle major challenges associated with fossil fuel-sourced energy consumption. Nafion, a perfluorosulfonic acid (PFSA) membrane that has high proton conductivity and good chemical stability, is a standard proton exchange membrane (PEM) used in PEMFCs. However, PEM degradation is one of the significant issues in the long-term operation of PEMFCs. Membrane degradation can lead to a decrease in the performance and the lifespan of PEMFCs. The membrane can degrade through chemical, mechanical, and thermal pathways. This paper reviews the different causes of all three routes of PFSA degradation, underlying mechanisms, their …

Strain-Dependent Activity-Stability Relations In Ruo2 And Iro2 Oxygen Evolution Catalysts, Payal Chaudhary, Alexandra Zagalskaya, Herbert Over, Vitaly Alexandrov

Department of Chemical and Biomolecular Engineering: Faculty Publications

Strain engineering is an effective strategy in modulating activity of electrocatalysts, but the effect of strain on electrochemical stability of catalysts remains poorly understood. In this work, we combine ab initio thermodynamics and molecular dynamics simulations to examine the role of compressive and tensile strain in the interplay between activity and stability of metal oxides considering RuO₂ and IrO₂ as exemplary catalysts. We reveal that although compressive strain leads to improved activity via the adsorbate-evolving mechanism of the oxygen evolution reaction, even small strains should substantially destabilize these catalysts promoting dissolution of transition metals. In contrast, our results …

Machine Learning And Metabolic Model Guided Crispri Reveals A Central Role For Phosphoglycerate Mutase In Chlamydia Trachomatis Persistence, Niaz Bahar Chowdhury, Nick Pokorzynski, Elizabeth A. Rucks, Scot P. Ouellette, Rey A. Carabeo, Rajib Saha

Department of Chemical and Biomolecular Engineering: Faculty Publications

Upon nutrient starvation, Chlamydia trachomatis serovar L2 (CTL) shifts from its normal growth to a non-replicating form, termed persistence. It is unclear if persistence is an adaptive response or lack of it. To understand that transcriptomics data were collected for nutrientsufficient and nutrient-starved CTL. Applying machine learning approaches on transcriptomics data revealed a global transcriptomic rewiring of CTL under stress conditions without having any global stress regulator. This indicated that CTL’s stress response is due to lack of an adaptive response mechanism. To investigate the impact of this on CTL metabolism, we reconstructed a genome-scale metabolic model of CTL (iCTL278) …

Vapor-Phase Synthesis Of Electrocatalytic Covalent Organic Frameworks, Syed Ibrahim Gnani Peer Mohamed, Shahriar Namvar, Tan Zhang, Hessam Shahbazi, Zhen Jiang, Andrew M. Rappe, Amin Salehi-Khojin, Siamak Nejati

Department of Chemical and Biomolecular Engineering: Faculty Publications

The inability to process many covalent organic frameworks (COFs) as thin films plagues their widespread utilization. Herein, a vapor-phase pathway for the bottom-up synthesis of a class of porphyrin-based COFs is presented. This approach allows integrating electrocatalysts made of metal-ion-containing COFs into the electrodes’ architectures in a single-step synthesis and deposition. By precisely controlling the metal sites at the atomic level, remarkable electrocatalytic performance is achieved, resulting in unprecedentedly high mass activity values. How the choice of metal atoms, i.e., cobalt and copper, can determine the catalytic activities of POR-COFs is demonstrated. The theoretical data proves that the Cu site …

Surface Antibody Changes Protein Corona Both In Human And Mouse Serum But Not Final Opsonization And Elimination Of Targeted Polymeric Nanoparticles, Sara Capolla, Federico Colombo, Luca De Maso, Prisca Mauro, Paolo Bertoncin, Thilo Kähne, Alexander Engler, Luis Núñez, Gustavo Larsen, Et Al.

Department of Chemical and Biomolecular Engineering: Faculty Publications

Background: Nanoparticles represent one of the most important innovations in the medical field. Among nanocarriers, polymeric nanoparticles (PNPs) attracted much attention due to their biodegradability, biocompatibility, and capacity to increase efficacy and safety of encapsulated drugs. Another important improvement in the use of nanoparticles as delivery systems is the conjugation of a targeting agent that enables the nanoparticles to accumulate in a specific tissue. Despite these advantages, the clinical translation of therapeutic approaches based on nanoparticles is prevented by their interactions with blood proteins. In fact, the so-formed protein corona (PC) drastically alters the biological identity of the particles. Adsorbed …

Integrative Transcriptomics And Proteomics Profiling Of Arabidopsis Thaliana Elucidates Novel Mechanisms Underlying Spaceflight Adaptation, Gbolaga O. Olanrewaju, Natasha J. Haveman, Michael J. Naldrett, Anna-Lisa Paul, Robert J. Ferl, Sarah E. Wyatt

Nebraska Center for Biotechnology: Faculty and Staff Publications

Spaceflight presents a unique environment with complex stressors, including microgravity and radiation, that can influence plant physiology at molecular levels. Combining transcriptomics and proteomics approaches, this research gives insights into the coordination of transcriptome and proteome in Arabidopsis’ molecular and physiological responses to Spaceflight environmental stress. Arabidopsis seedlings were germinated and grown in microgravity (μg) aboard the International Space Station (ISS) in NASA Biological Research in Canisters – Light Emitting Diode (BRIC LED) hardware, with the ground control established on Earth. At 10 days old, seedlings were frozen in RNA-later and returned to Earth. RNA-seq transcriptomics and TMTlabeled LC-MS/MS proteomic …

A Multi-Organ Maize Metabolic Model Connects Temperature Stress With Energy Production And Reducing Power Generation, Niaz Bahar Chowdhury, Margaret Simons- Senftle, Berengere Decouard, Isabelle Quillere, Martine Rigault, Karuna Anna Sajeevan, Bibek Acharya, Ratul Chowdhury, Bertrand Hirel, Alia Dellagi, Costas Maranas, Rajib Saha

Department of Chemical and Biomolecular Engineering: Faculty Publications

Climate change has adversely affected maize productivity. Thereby, a holistic understanding of metabolic crosstalk among its organs is important to address this issue. Thus, we reconstructed the first multi-organ maize metabolicmodel, iZMA6517, and contextualized itwith heat and cold stress transcriptomics data using expression distributed reaction flux measurement (EXTREAM) algorithm. Furthermore, implementing metabolic bottleneck analysis on contextualized models revealed differences between these stresses. While both stresses had reducing power bottlenecks, heat stress had additional energy generation bottlenecks.We also performed thermodynamic driving force analysis, revealing thermodynamics-reducing power-energy generation axis dictating the nature of temperature stress responses. Thus, a temperaturetolerant maize ideotype can …

Conduction Mechanism Switching From Coulomb Blockade To Classical Critical Percolation Behavior In Disordered Nanoparticle Array, Abhijeet Prasad, Jay Min Lim, Ravi Saraf

Department of Chemical and Biomolecular Engineering: Faculty Publications

Large, open-gate transistors made from metal nanoparticle arrays offer possibilities to build new electronic devices, such as sensors. A nanoparticle necklace network (N³) of Au particles from 300 K to cryogenic temperatures exhibit a nonohmic I–V_d behavior, I ≈ (V_d–V_T)^𝜻, where V_T is a conduction gap and 𝜻 is a constant critical exponent. The conduction gap in N³, made from disordered networks of 1D chains of 10 nm diameter Au particles exhibits room temperature (RT) gating. Although the I–V_d behavior at RT is identical to Coulomb blockade, …

Exploring The Use Of Virtual Reality In Designing And Prototyping Medical Devices, Evan Marsh

Honors Program: Senior Projects (Public)

A degree in engineering is highly sought after in the United States. Despite the grueling coursework and sacrifices involved in earning an engineering degree, the rewards after college are numerous. However, the engineering field is vast, and the degree obtained is not always the profession followed in industry. A lot of what we learn in the college of engineering is very broad and surface-level. It is worth noting that only about 10% of what engineering students learn in school is applicable in the workplace, but they wish they had learned a lot more about that 10%.

Mass Spectrometry Of The White Adipose Metabolome In A Hibernating Mammal Reveals Seasonal Changes In Alternate Fuels And Carnitine Derivatives, Frazer I. Heinis, Sophie Alvarez, Matthew T. Andrews

Nebraska Center for Biotechnology: Faculty and Staff Publications

Mammalian hibernators undergo substantial changes in metabolic function throughout the seasonal hibernation cycle. We report here the polar metabolomic profile of white adipose tissue isolated from active and hibernating thirteen-lined ground squirrels (Ictidomys tridecemlineatus). Polar compounds in white adipose tissue were extracted from five groups representing different timepoints throughout the seasonal activity-torpor cycle and analyzed using hydrophilic interaction liquid chromatography-mass spectrometry in both the positive and negative ion modes. A total of 224 compounds out of 660 features detected after curation were annotated. Unsupervised clustering using principal component analysis revealed discrete clusters representing the different seasonal timepoints throughout hibernation. One-way …

Protocol To Develop A Synthetic Biology Toolkit For The Non-Model Bacterium R. Palustris, Mark Kathol, Cheryl Immethun, Rajib Saha

Department of Chemical and Biomolecular Engineering: Faculty Publications

Numerous biology tools are developed to work for model organisms, which, however, do not work effectively in non-model organisms. Here, we present a protocol for developing a synthetic biology toolkit for Rhodopseudomonas palustris CGA009, a non-model bacterium with unique metabolic properties. We describe steps for introducing and characterizing biological devices in nonmodel bacteria, such as the utilization of fluorescence markers and RT-qPCR. This protocol may also be applicable for other non-model organisms. For complete details on the use and execution of this protocol, please refer to Immethun et al..¹

Blood Flow Regulates Atherosclerosis Progression And Regression, Morgan A. Schake

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Atherosclerosis is the most prevalent pathology of cardiovascular disease with no known cure. Despite the many systemic risk factors for atherosclerosis, plaques do not form randomly in the vasculature. Instead, they form around bifurcations and the inner curvature of highly curving arterial segments that contain so-called disturbed blood flow that is low in magnitude and multidirectional over the cardiac cycle. Conversely, straight, non-bifurcated arterial segments that contain moderate-to-high and unidirectional (i.e., normal) blood flow are protected from plaque development. Thus, blood flow is a key regulator of atherosclerosis that may be able to be leveraged to develop new therapeutics. Towards …

Mitochondrial Complex Iii Bypass Complex I To Induce Ros In Gpr17 Signaling Activation In Gbm, Sana Kari, Jeyalakshmi Kandhavelu, Akshaya Murugesan, Ramesh Thiyagarajan, Srivatsan Kidambi, Meenakshisundaram Kandhavelu

Department of Chemical and Biomolecular Engineering: Faculty Publications

Guanine nucleotide binding protein (G protein) coupled receptor 17 (GPR17) plays crucial role in Glioblastoma multiforme (GBM) cell signaling and is primarily associated with reactive oxidative species (ROS) production and cell death. However, the underlying mechanisms by which GPR17 regulates ROS level and mitochondrial electron transport chain (ETC) complexes are still unknown. Here, we investigate the novel link between the GPR17 receptor and ETC complex I and III in regulating level of intracellular ROS (ROSi) in GBM using pharmacological inhibitors and gene expression profiling. Incubation of 1321N1 GBM cells with ETC I inhibitor and GPR17 agonist decreased the ROS level, …

A Device For Measuring Acoustic Output Intensity Of Transcranial Doppler Ultrasound Transducers For Comparison With Fda Regulations, Sarah Altman, Gregory Bashford, Benjamin Hage

Honors Program: Senior Projects (Public)

Transcranial Doppler Ultrasonography (TCD) is a non-invasive methodology which can evaluate cerebral blood flow velocity in real time. Single-element focused circular transducers placed on the scalp produce ultrasound waves capable of penetrating the skull with minimal aberration, enabling measurement of the Doppler shift. As such, TCD can measure blood flow velocity in the internal carotid and vertebral arteries, as well as the arteries of the Circle of Willis: the Anterior Cerebral (ACA), Posterior Cerebral (PCA), and Middle Cerebral Arteries (MCA). Intracranial aneurysm and ischemic stroke are serious conditions in which ballooning or occlusion of cerebral vessels cause insufficient perfusion, leading …