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You searched for +publisher:"Cornell University" +contributor:("Kirby,Brian"). Showing records 1 – 3 of 3 total matches.

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Cornell University

1. Johnson, Lilian. Micromechanics and rheology of colloidal gels via dynamic simulation .

Degree: 2018, Cornell University

Colloidal gels are soft solids comprising a viscoelastic, networked structure embedded in solvent. This network forms from microscopically small particles initially dispersed in a solvent which self-assemble into a hierarchical, space-spanning network of particles connected by physical bonds. When subjected to external forces, colloidal gels exhibit a solid-to-liquid transition yet regain elastic character when forcing is removed. Their tunable mechanical properties and ability to flow enable colloidal gels to serve as the foundation of a multitude of applications ranging from everyday products, like yogurt, to biomedical applications, such as injectable therapeutics. The nonlinear rheology of colloidal gels underlies their utility in nearly every application, for example, spreading, injecting, or pouring. The transition from rest to steady flow of colloidal gels is characterized by one or more stress overshoots indicative of gel yield. In strongly-bonded, dilute colloidal gels, yield is hypothesized to result from the catastrophic loss of the network structure. Solid-like fracture leading to fluidization of strongly bonded gels may not be relevant where particle strands are not single-particle thick chains but rather bicontinuous and time-evolving due to reversible bonds. The connections between gel yield and the structural evolution of dense, bicontinuous gels remains poorly understood due to the difficulty of imaging of the internal structure of dense particulate gels with sufficient time resolution in experiments and due to the large system size required in computational studies. Here we report large-scale dynamic simulation to study reversible colloidal gels to elucidate the micromechanical underpinnings of non-Newtonian behavior of soft materials and to understand ongoing phase separation. First, we show that the startup of a fixed strain rate reveals that colloidal gel yield, separating the short-time solid-like response from the long-time liquid-like response, can be framed as a transition in energy storage. Contrary to prior hypotheses connecting yield to loss of network connectivity, the network persists after flow startup and a predictive model connecting hierarchical structure to early-time stress growth is presented. We devised a novel approach to monitor bond stretching, compression, formation, and loss alongside macroscopic deformation. We find that changes in structure that underlie the stress growth and post-yield relaxation, as monitored by bond dynamics, indicate the switch from energy storage to release. After rheological yield, energy release continues if flow is sufficiently strong; however, when imposed flow is weak, energy release reverses after yield, and the gel densifies. This gives the important result that yield under weak flow can be viewed as a release from kinetic arrest, permitting the gel to evolve toward more complete phase separation. This supports our view that yield of weakly sheared gels is a `non-equilibrium phase transition'. Second, we compare our simulations to… Advisors/Committee Members: Kirby, Brian (committeeMember), Clancy, Paulette (committeeMember).

Subjects/Keywords: Simulation; Chemical engineering; Rheology; Colloidal gels

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Johnson, L. (2018). Micromechanics and rheology of colloidal gels via dynamic simulation . (Thesis). Cornell University. Retrieved from http://hdl.handle.net/1813/64849

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Johnson, Lilian. “Micromechanics and rheology of colloidal gels via dynamic simulation .” 2018. Thesis, Cornell University. Accessed August 05, 2020. http://hdl.handle.net/1813/64849.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Johnson, Lilian. “Micromechanics and rheology of colloidal gels via dynamic simulation .” 2018. Web. 05 Aug 2020.

Vancouver:

Johnson L. Micromechanics and rheology of colloidal gels via dynamic simulation . [Internet] [Thesis]. Cornell University; 2018. [cited 2020 Aug 05]. Available from: http://hdl.handle.net/1813/64849.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Johnson L. Micromechanics and rheology of colloidal gels via dynamic simulation . [Thesis]. Cornell University; 2018. Available from: http://hdl.handle.net/1813/64849

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Cornell University

2. Roberts, LaDeidra Monet. HOW MICROVESICLES ARE "BUDDING" INTO THE CANCER CONVERSATION: THE ROLE OF GLYCOCALYX-INDUCED MEMBRANE BENDING .

Degree: 2019, Cornell University

Cancer intercellular communication has been recognized to occur by direct cell-to-cell contact as well as local paracrine signaling between cancer and normal cells. However, tumor-derived extracellular vesicles (EVs), which are lipid bilayer vesicles released from cancer cells, can travel long distances in the body and cytosolically deliver oncogenic cargos, such as DNA, RNA, and proteins, to normal cells and contribute to tumor progression and metastases. Microvesicles, a specific EV subtype, directly shed from the plasma membrane, but how this occurs is not fully elucidated. To help address this, there is a need for consistent convention and methodology to clearly differentiate and fully characterize subtypes of EVs to understand their contributions in cancer and what direct cancer-related paradigms impact their expression. Here, we assess a range of techniques commonly used for detection of EVs to confirm reliable methods for characterization of vesicles. We combined scanning electron microscopy and cryo-transmission electron microscopy for visualization of EVs along with nanoparticle tracking analysis for diameter distributions and quantification. We found these methods to be reliable in characterizing and differentiating EV subtypes. We then used these techniques along with our genetically encoded toolbox of synthetic to native glycocalyx biopolymers to understand the role of the glycocalyx in membrane bending and microvesicle biogenesis. We demonstrate that molecular crowding on the plasma membrane by flexible glycocalyx biopolymers allows membrane bending to occur. Moreover, in coordination with the actin cytoskeleton, glycocalyx biopolymers induce membrane bending required for generation of shapes, including tubules and pearling instabilities that are consistent with microvesicles. Next, we explored properties that were found to be important for inducing membrane bending and MV shedding. Particularly, we found that the MV shedding was dependent on the flexible polymer domain. Further, we investigated whether extracellular cues such as physical confinement modulates MV shedding. Ultimately, these studies highlight the glycocalyx from a biophysical perspective in understanding microvesicle biogenesis in cancer. Thus, these key insights can potentially lead to new targeted therapeutic approaches in the mitigation of cancer metastasis. Advisors/Committee Members: Reesink, Heidi L. (committeeMember), Kirby, Brian (committeeMember), Fischbach, Claudia (committeeMember).

Subjects/Keywords: microvesicles; mucin; extracellular vesicles; Biomedical engineering; cancer; glycocalyx; membrane curvature

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Roberts, L. M. (2019). HOW MICROVESICLES ARE "BUDDING" INTO THE CANCER CONVERSATION: THE ROLE OF GLYCOCALYX-INDUCED MEMBRANE BENDING . (Thesis). Cornell University. Retrieved from http://hdl.handle.net/1813/67661

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Roberts, LaDeidra Monet. “HOW MICROVESICLES ARE "BUDDING" INTO THE CANCER CONVERSATION: THE ROLE OF GLYCOCALYX-INDUCED MEMBRANE BENDING .” 2019. Thesis, Cornell University. Accessed August 05, 2020. http://hdl.handle.net/1813/67661.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Roberts, LaDeidra Monet. “HOW MICROVESICLES ARE "BUDDING" INTO THE CANCER CONVERSATION: THE ROLE OF GLYCOCALYX-INDUCED MEMBRANE BENDING .” 2019. Web. 05 Aug 2020.

Vancouver:

Roberts LM. HOW MICROVESICLES ARE "BUDDING" INTO THE CANCER CONVERSATION: THE ROLE OF GLYCOCALYX-INDUCED MEMBRANE BENDING . [Internet] [Thesis]. Cornell University; 2019. [cited 2020 Aug 05]. Available from: http://hdl.handle.net/1813/67661.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Roberts LM. HOW MICROVESICLES ARE "BUDDING" INTO THE CANCER CONVERSATION: THE ROLE OF GLYCOCALYX-INDUCED MEMBRANE BENDING . [Thesis]. Cornell University; 2019. Available from: http://hdl.handle.net/1813/67661

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. LaValley, Danielle Judith. Effects of Tumor Microenvironmental Cues on Endothelial Cell Behavior and Chemotherapeutic Efficiency .

Degree: 2018, Cornell University

Cancer is a leading cause of death worldwide and within the US. While cancer initially arises from genetic mutations that transform otherwise healthy cells into cancerous cells, the growth, expansion, and metastasis of malignant tumors is dictated by local mechanical and biological cues, collectively known as the tumor microenvironment. Accordingly, to successfully treat cancer, one must target microenvironmental cues that emerge from tumor-associated stromal cells and extracellular matrix, in addition to the cancer cells. However, most cancer therapeutics do not effectively eradicate the disease, highlighting the need to improve our knowledge of cancer biology and develop novel treatments to target cancerous phenotypes with minimal side effects. Thus, the objectives of this dissertation are two-fold: to expand our current understanding of molecular mechanisms involved in tumor angiogenesis that contribute to cancer progression, and to create a human-based platform to screen anti-cancer therapeutics. During tumor progression, the cancer microenvironment evolves both chemically and mechanically. In line with the first goal above, endothelial cell behavior was investigated as a function of increased extracellular matrix stiffness and elevated vascular endothelial growth factor (VEGF) production, two known characteristics of the tumor microenvironment. My data indicate additive effects from both stimuli on VEGF receptor internalization, endothelial signaling, and proliferation, emphasizing the need to design cancer therapeutics to target multiple signaling pathways. While basic research such as that from goal number one can shed light on therapeutic targets, this basic science must subsequently be utilized in translational studies. Therefore, in line with the second goal, I designed a body-on-a-chip microfluidic device to investigate tumor-specific factors in cancer drug development. Such systems are critical in translating cancer biology research within drug screening models. My design creates a physiologically-relevant model to test both efficacy and toxicity of anti-cancer drugs, promoting unidirectional flow on a pumpless platform and using multicellular tumor spheroids as realistic tumor models. My data reveal both chemotherapeutic-induced cytotoxicity to the intended cancer cells and undesired toxic side effects in distant organs. Collectively, the data in this dissertation present a multifaceted approach to improve cancer treatment where basic science advances are translated to human-based drug screening systems. Advisors/Committee Members: Weiss, Robert S. (committeeMember), Kirby, Brian (committeeMember), King, Cynthia A. (committeeMember).

Subjects/Keywords: Biomedical engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

LaValley, D. J. (2018). Effects of Tumor Microenvironmental Cues on Endothelial Cell Behavior and Chemotherapeutic Efficiency . (Thesis). Cornell University. Retrieved from http://hdl.handle.net/1813/64986

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

LaValley, Danielle Judith. “Effects of Tumor Microenvironmental Cues on Endothelial Cell Behavior and Chemotherapeutic Efficiency .” 2018. Thesis, Cornell University. Accessed August 05, 2020. http://hdl.handle.net/1813/64986.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

LaValley, Danielle Judith. “Effects of Tumor Microenvironmental Cues on Endothelial Cell Behavior and Chemotherapeutic Efficiency .” 2018. Web. 05 Aug 2020.

Vancouver:

LaValley DJ. Effects of Tumor Microenvironmental Cues on Endothelial Cell Behavior and Chemotherapeutic Efficiency . [Internet] [Thesis]. Cornell University; 2018. [cited 2020 Aug 05]. Available from: http://hdl.handle.net/1813/64986.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

LaValley DJ. Effects of Tumor Microenvironmental Cues on Endothelial Cell Behavior and Chemotherapeutic Efficiency . [Thesis]. Cornell University; 2018. Available from: http://hdl.handle.net/1813/64986

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.