Biomedical Engineering and Bioengineering Commons^™

Enhanced Hot Electron Lifetimes In Quantum Wells With Inhibited Phonon Coupling, Hamidreza Esmaielpour, Vincent R. Whiteside, Herath P. Piyathilaka, Sangeetha Vijeyaragunathan, Bin Wang, Echo Adcock-Smith, Kenneth P. Roberts, Tetsuya D. Mishima, Michael B. Santos, Alan D. Bristow, Ian R. Sellers

Faculty & Staff Scholarship

Hot electrons established by the absorption of high-energy photons typically thermalize on a picosecond time scale in a semiconductor, dissipating energy via various phonon-mediated relaxation pathways. Here it is shown that a strong hot carrier distribution can be produced using a type-II quantum well structure. In such systems it is shown that the dominant hot carrier thermalization process is limited by the radiative recombination lifetime of electrons with reduced wavefunction overlap with holes. It is proposed that the subsequent reabsorption of acoustic and optical phonons is facilitated by a mismatch in phonon dispersions at the InAs-AlAsSb interface and serves to …

Targeting Ovarian Cancer And Endothelium With An Allosteric Ptp4a3 Phosphatase Inhibitor, Kelley E. Mcqueeney, Joseph M. Salamoun, James C. Burnett, Nektarios Barabutis, Paula Pekic, Sophie L. Lewandowski, Danielle C. Llaneza, Robert Cornelison, Yunpeng Bai, Zhong-Yin Zhang, John D. Catravas

Bioelectrics Publications

Overexpression of protein tyrosine phosphatase PTP4A oncoproteins is common in many human cancers and is associated with poor patient prognosis and survival. We observed elevated levels of PTP4A3 phosphatase in 79% of human ovarian tumor samples, with significant overexpression in tumor endothelium and pericytes. Furthermore, PTP4A phosphatases appear to regulate several key malignant processes, such as invasion, migration, and angiogenesis, suggesting a pivotal regulatory role in cancer and endothelial signaling pathways. While phosphatases are attractive therapeutic targets, they have been poorly investigated because of a lack of potent and selective chemical probes. In this study, we disclose that a potent, …

Transport Of Charged Small Molecules After Electropermeabilization - Drift And Diffusion, Esin B. Sözer, C. Florencia Pocetti, P. Thomas Vernier

Bioelectrics Publications

Background: Applications of electric-field-induced permeabilization of cells range from cancer therapy to wastewater treatment. A unified understanding of the underlying mechanisms of membrane electropermeabilization, however, has not been achieved. Protocols are empirical, and models are descriptive rather than predictive, which hampers the optimization and expansion of electroporation-based technologies. A common feature of existing models is the assumption that the permeabilized membrane is passive, and that transport through it is entirely diffusive. To demonstrate the necessity to go beyond that assumption, we present here a quantitative analysis of the post-permeabilization transport of three small molecules commonly used in electroporation research-YO-PRO-1, propidium, …

The Effect Of Tackling Training On Head Accelerations In Youth American Football, Eric Schussler, Richard J. Jagacinski, Susan E. White, Ajit M. Chaudhari, John A. Buford, James A. Onate

Rehabilitation Sciences Faculty Publications

Background: Many organizations have introduced frameworks to reduce the incidence of football related concussions through proper equipment fitting, coach education, and alteration of tackling technique.

Purpose: The purpose of this study was to examine the effects of training in a vertical, head up tackling style on the number of head accelerations experienced while tackling in a controlled laboratory situation. The authors hypothesized that training in a head up tackling technique would reduce the severity of head acceleration experienced by participants.

Design: Controlled Laboratory Study.

Methods: Twenty-four participants (11.5 ± 0.6 years old, 60.5 ± 2.2 in, 110 ± 18.4 lbs.) …

Divergent Scaling Of Miniature Excitatory Post-Synaptic Current Amplitudes In Homeostatic Plasticity, Amanda L. Hanes

Browse all Theses and Dissertations

Synaptic plasticity, the ability of neurons to modulate their inputs in response to changing stimuli, occurs in two forms which have opposing effects on synaptic physiology. Hebbian plasticity induces rapid, persistent changes at individual synapses in a positive feedback manner. Homeostatic plasticity is a negative feedback effect that responds to chronic changes in network activity by inducing opposing, network-wide changes in synaptic strength and restoring activity to its original level. The changes in synaptic strength can be measured as changes in the amplitudes of miniature post-synaptic excitatory currents (mEPSCs). Together, the two forms of plasticity underpin nervous system functions such …

A Purification And In Vitro Activity Assay For A (P)Ppgpp Synthetase From Clostridium Difficile, Astha Pokhrel, Asia Poudel, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

Kinase and pyrophosphokinase enzymes transfer the gamma phosphate or the beta-gamma pyrophosphate moiety from nucleotide triphosphate precursors to substrates to create phosphorylated products. The use of γ-³²-P labeled NTP precursors allows simultaneous monitoring of substrate utilization and product formation by radiography. Thin layer chromatography (TLC) on cellulose plates allows rapid separation and sensitive quantification of substrate and product. We present a method for utilizing the thin-layer chromatography to assay the pyrophosphokinase activity of a purified (p)ppGpp synthetase. This method has previously been used to characterize the activity of cyclic nucleotide and dinucleotide synthetases and is broadly suitable for …

Comparison Of Artificial Saliva Vs Saline Solution On Rate Of Suture Degradation In Oropharyngeal Surgery, Jenna W. Briddell, Luke Riexinger, Jove Graham, Donna M. Ebenstein

Faculty Journal Articles

IMPORTANCE Absorbable sutures are designed to degrade and lose strength over time. Manufacturers warn that exposure to various body fluids can change the estimated degradation rate of these sutures, but few studies have been conducted to quantify the degree of change associated with saliva.

OBJECTIVE To quantify the association of increased loss of strength of sutures over time after exposure to artificial saliva (hereinafter referred to as “saliva”).

DESIGN, SETTING, AND PARTICIPANTS This experimental in vitro study was conducted at Bucknell University (Lewisburg, Pennsylvania) from June 19, 2015, to July 4, 2015. No participants were involved. The loss of strength …

Degradability Of Poly(Ethylene) Based Microgels And Methods Of Improving High Polydispersity Index, Abrar Alniemi

Williams Honors College, Honors Research Projects

In order to improve upon the utilization of poly(ethylene glycol) (PEG) microgel-based scaffolds in drug delivery applications, this work explores the use of degradable and non-degradable PEG for tunable scaffolds. Previously, issues concerning the required uniformity in microgel size and low polydispersity index have been encountered. As such, methods of refining polymer synthesis, microgel fabrication, and microgel size separation were explored. Overall, no solution has been found to correct the issue for the microgels were still observed to have high polydispersity index regardless of varied troubleshooting alterations.

Inverse Kinematic Assessment Of Rehabilitative Therapy In Children Using Orthotics, Michael P. Murphy, Jacob R. Rammer, Kaleb L. Vinohout, Meghan R. Caballero, Christy M. Cornwell, Jessica M. Fritz, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Pathologic movement patterns are characterized by abnormal kinematics that alter how muscles support the body during walking. Individual muscles are often the target of interventions with physical therapy and surgery alike, yet the tools to assess individual muscles clinically remain limited. The aim of this study is to assess OpenSim as a clinical tool for individualized rehabilitative evaluation of children using orthotics. This anatomic and kinematic modeling study was focused on pre- and post-treatment assessment of gait characteristics in fourteen children using orthotic devices. A range of four to twelve acceptable gait capture trials was collected for each child before …

Development Of Entubulation Strategies For Treating Central Nervous System Injuries, Ivy Brosch

Williams Honors College, Honors Research Projects

According to the McKnight Brain Institute, at least 10,000 people annually in the USA suffer from a central nervous system (CNS) injury. These injuries can cause serve disabilities including paralysis. Due to the complexity of the spinal cord, it is common that potential CNS treatments are first applied to an optic nerve crush (ONC) model in rats. Two proposed treatments were employed; one where nerve growth factor (NGF) was immobilized to a chitosan substrate to stimulate axonal regeneration, and the other using pentadecafluorooctanoyl chloride modified methacrylamide chitosan (MAC(Ali15)F) hydrogel to enhance local oxygenation. The two different treatments were formed into …

Wearable Hearing Accessory Technology, Tyler Cindea, Jaime Alcorn, Brooke Draper, Kyle Glascott, Ben Hanna, Robert Thoerner

Williams Honors College, Honors Research Projects

We set out in August 2017 to develop an active noise suppressing device that would be usable both in military and civilian activities. Due to constraints in knowledge and time, we decided our best course of action was to divide the project into two equal projects with the hope to be able to combine them into a single project at the end of the allotted time. This consisted of an active noise suppression device and a passive noise suppression device. The passive device would have no electronic components and the active device would be pure circuitry with no housing. This …

Identification Of Streptococcus Pyogenes Using Raman Spectroscopy, Ehsan Majidi

Wayne State University Dissertations

Despite the attention that Raman Spectroscopy has gained recently in the area of pathogen identification, the spectra analyses techniques are not well developed. In most scenarios, they rely on expert intervention to detect and assign the peaks of the spectra to specific molecular vibration. Although some investigators have used machine-learning techniques to classify pathogens, these studies are usually limited to a specific application, and the generalization of these techniques is not clear. Also, a wide range of algorithms have been developed for classification problems, however, there is less insight to applying such methods on Raman spectra. Furthermore, analyzing the Raman …

Restoring Cholesterol Homeostasis In Familial Hypercholesterolemia Cell Line Model, Lubna Hindi

Electronic Theses and Dissertations

Familial hypercholesterolemia (FH) is an autosomal dominant disorder that results in elevated levels of low-density lipoprotein cholesterol (LDL-C). This increase in serum cholesterol level has been shown to result in premature coronary artery disease (CAD) with devastating symptoms from a young age. Today, the prevalence of heterozygous FH (HeFH) and homozygous FH (HoFH) is estimated to be 1 in 320 and 1 in 160,000 people, respectively. FH is referred to as an underdiagnosed disease due to the large number of mutations that continues to grow. These mutations often exist in one of or a combination of three genes: low-density lipoprotein …

Optimization Of Plga And Plga-Dasatinib Particles Through A Taguchi Design Approach, Rayeanne N Balgemann

Electronic Theses and Dissertations

Proliferative vitreoretinopathy (PVR) is a disease of the retina in the human eye. Retinal pigment epithelium cells (RPE) undergo an epithelial to mesenchymal transition in response to retinal trauma. This transition gives the cells mobility and allows them to potentially infiltrate the vitreous chamber and deposit on either side of the retina. Once cell deposition has occurred, along with several other transformed cells derived from cell types such as Müller glia, these migratory cells can form a membrane contiguous with the retinal extracellular matrix and, upon contraction, cause wrinkling of the retina. If left untreated PVR can lead to traction …

Molded Features In Pdms For Fabricating Bacterial Cellulose For Various Geometries, Mitchell Habegger

Williams Honors College, Honors Research Projects

The purpose of producing features on bacterial cellulose (BC) is to facilitate the elongation and alignment for cells, in this case Normal Human Dermal Fibroblast (NHDF) cells. The elongated cells have applications in wound healing, tissue engineering, disease diagnostics, and many other fields. Experiments were run to test the effectiveness of transferring features to BC sheets from features induced by fracturing on polydimethylsiloxane (PDMS) and those duplicated from molds with existing features. The features were duplicated to BC sheets by either air drying or Guided Assembly-Based Biolithography (GAB). The research results showed that fracture inducing on PDMS produced very small …

Modification Of Bacterial Cellulose Using Organosilanes To Enhance Cell Adhesion And Growth, Kristi Ferrato

Williams Honors College, Honors Research Projects

In this project, drying bacterial cellulose (BC) to maintain its structural integrity, and treating BC with organosilanes 3-aminopropyltriethoxysilane (APTES) and (3-Mercaptopropyl)trimethoxysilane (MPTMS) as well as with various concentration of gelatin to increase the cells per area was studied. Drying BC with hexamethyldisilazane (HMDS) by soaking the BC in ascending concentrations of ethanol and HMDS did not protect the structural integrity of the BC grown in lab but did for the BC grown in Dr. Siriporn Taokaew’s lab. Freeze drying also did not fully protect the structural integrity as the BC was placed in a freezer for several hours at -20oC …

A Novel Approach For Cancer Characterization Using Latent Dirichlet Allocation And Disease-Specific Genomic Analysis, Hima Bindu Yalamanchili

Browse all Theses and Dissertations

Two challenging problems in the clinical study of cancer are the characterization of cancer subtypes and the classification of individual patients according to those subtypes. Further, understanding the role of differential gene expression in the development of and molecular response to cancer is a complex problem that remains challenging, in part due to the sheer number of genes and gene products involved. Traditional statistical approaches addressing these problems are hindered by within-class heterogeneity and challenges inherent in data integration across high-dimensional data. In addition, many current machine learning methods do not lend themselves to biological interpretation. We have developed a …

M1 To M2 Macrophage Induction Using Retinoic Acid And Mesenchymal Stem Cells Loaded On An Electrospun Pullulan/Gelatin Scaffold To Promote Healing Of Chronic Wounds, Kaivon Assani

Browse all Theses and Dissertations

Modulation of macrophage polarization is required for effective tissue repair and regenerative therapies. Conversion of macrophages from inflammatory M1 to fibrotic M2 phenotype could help in diseases such as chronic wound which are stuck in inflammatory state. During the inflammatory phase, macrophages are of the inflammatory phenotype (M1) and distribute pro-inflammatory cytokines including TNF-a and IL1[beta] which are microbicidal and recruit/activate cells. In normal wound healing macrophages then switch to a fibrotic phenotype (M2) promoting wound closure by angiogenesis, and matrix deposition. Chronic wounds are a major biological and financial burden to both patients and the health care system, costing …

Effect Of Dimensionality On In Vitro Growth Environment And Mesenchymal Stem Cell Function, Fatema Tuj Zohora

Browse all Theses and Dissertations

The use of the standard two dimensional (2D) cell culture has laid down the fundamentals of molecular and cell biology. However, recent advances in cell-based regenerative medicine raises the concern on deconstructing cellular behaviors in more physiologically relevant three dimensional (3D) microenvironments. Differences in cell response in 2D versus 3D systems arise from the perturbations in gene expression patterns that stem from how cells sense their underlying 2D or surrounding 3D matrices and adjust their phenotypes accordingly. Thus, cells are no longer considered as a solitary entity of genome but a context arises from a combinatorial interactions of cell-ECM, cell-cell, …

Novel Auto-Calibrating Neural Motor Decoder For Robust Prosthetic Control, Andrew Earl Montgomery

Browse all Theses and Dissertations

The overarching goal of this project is to develop novel neural motor decoders for prosthetic control. EMG decoders measure the activity from an intact but non-target muscle. Neural motor decoders transform the signal measured from the severed motor axons of the target muscle. A multi-scale, highly-realistic computer model of a spinal motor pool was developed (Allen & Elbasiouny, 2018) to serve as a computational platform for decoder development and testing. A firing rate-based algorithm was developed to transform the aggregate discharge of the motor pool into a command signal to control the simulated prosthetic MuJoCo hand. This algorithm was informed …