Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 37-38). / The desire to desire targeted drug delivery devices capable of releasing therapeutic payloads within the cytosol of cells has led to research on nanoparticles as suitable drug carriers. Recently, it was shown that gold nanoparticles coated in striped, alternating layers of hydrophobic and hydrophilic ligands are capable of non-disruptively penetrating a lipid bilayer, a discovery with potential implications in drug delivery. While the reaction mechanism is not known, initial experimental results indicate that endocytosis and membrane poration could be ruled as possible mechanisms. In this work, we explore the reaction mechanism of membrane penetration using a coarse-grained Brownian Dynamics model. We also define a Monte Carlo simulation for modeling ligand motion on the nanoparticle surface based on a single order parameter, and describe a method for approximating the interaction energy with the bilayer as a function of this parameter. Our simulations demonstrate the dependence of nanoparticles penetration on the surface mobility, not explicit conformation, of coated ligands. They demonstrate that while nanoparticles with static ligands in a striped conformation are unable to penetrate the bilayer, enabling surface mobility allows penetration by the induced formation of a small, transient pore of a comparable size to the nanoparticle. Our results offer an enhanced understanding of the nanoparticles-bilayer interaction and an identification of the property necessary for membrane penetration. / by Reid Chi Van Lehn. / S.B.

Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 111-120). / Synthetic biology is a rapidly growing engineering discipline widely used in biotechnological applications. However, there are few examples of using synthetic biology in product design and there are even fewer - perhaps no - examples of incorporating fluids containing synthetic organisms and biomolecules into a product. The goals of this thesis are two-fold. First, the author investigates how to contain and control fluids in 3D printed fluid channels. 3D printing methods are characterized by their ability to create fluidic channels that are compatible with biochemistry and culturing microorganisms. Second, the author explores how to design the materiality and geometry of the fluid channels to affect biological function. These goals are pursued in two distinct projects: DNA assembly in 3D printed fluidics and Mushtari, a fluidic wearable designed to contain cyanobacteria and E. coli cultures. Contributions include (1) characterizing the resolution of three 3D printing methods for creating fluidic channels, (2) demonstrating compatibility of 3D printing methods with cell culture and DNA assembly biochemistry, (3) demonstrating the capability to print wearable-scale millifluidic networks up to 58 meters in length, and (4) developing approaches for fabricating geometrically complex fluidic systems. / by William Graham Patrick. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003. / Includes bibliographical references (leaves 77-80). / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / The {111}<112̄> shear stress-displacement behavior for face-centered cubic (fcc) metals, aluminum and copper, is calculated using empirical potentials proposed by Mishin and by Ercolessi, based on the embedded atom method (EAM), and compared with published ab initio calculations. In copper close agreement is observed in the results given by the Mishin potential for both the ideal shear strength and local atomic relaxation during shear, although the extent of plastic deformation before failure is over-predicted. In aluminum, both the Mishin and Ercolessi potentials are used, with only the former able to capture the majority of the behavior exhibited in first principle calculations. Both potentials are shown to have difficulties modeling the effects of directional bonding. Calculations of the multiplane generalized stacking fault energy in both materials reveal that aluminum has a longer range of atomic interaction than copper. Using molecular dynamics and static energy calculations, deformation twins are shown to form by homogeneous nucleation, slip and subsequent coalescence of partial dislocations in both copper and aluminum. The minimum energy path for formation of a two-layer microtwin, and the energy barriers to its further growth are analyzed for the two metals. The mechanism observed is interpreted with reference to existing work on the nucleation of microtwins in body-centered cubic metals. / by Robert D. Boyer. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 85-90). / Many important areas of research regarding human health, such as immunology and cancer biology, deal with highly heterogeneous populations of cells where the contributions of individual players cannot be ignored. Single-cell technologies aim to resolve this heterogeneity by analyzing many individual cells in a high-throughput manner. Here we developed two examples of such tools that rely on microfabricated arrays of microwells. The first platform merges fluorescence cytometry with label-free profiling of the small molecule composition of tens of thousands of cells based on matrix assisted laser desorption/ionization (MALDI) mass spectrometry. We evaluated several materials and approaches to chip fabrication suitable for interfacing with a MALDI instrument. We also developed an analytical pipeline for efficient processing of cells on the chip and demonstrated its application to the analysis of brain tumor samples. The second platform provides a new format of microwell arrays for fluorescence cytometry that improves their compatibility with a range of automated equipment and enables more efficient processing of a greater number of samples, while preserving viability and identity of cells for subsequent analyses. We demonstrated its utility for on-chip enrichment and recovery of circulating tumor cells (CTCs) and high-content immuno phenotyping of small clinical samples. / by Denis Loginov. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1990. / Vita. / Includes bibliographical references (leaves 141-145). / by Paul Robert Nahass. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996. / Includes bibliographical references (p. 144-146). / by Charles William Rowe. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995. / Vita. / Includes bibliographical references (p. 71-73). / by Caryl Burnette Brown. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996. / Includes bibliographical references (leaves 97-98). / by Christy S. Choi. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references. / Developing cost effective technologies that convert low-grade heat into electricity is essential to meet the increasing demand for renewable energy systems. Thermoelectric and recently emergent electrochemical heat conversion devices are promising candidates for this purpose. However, current performance and cost of these devices limit their widespread application. In this thesis, we investigate design guidelines for heterostructured thermoelectric systems and electrochemical heat energy harvesters to address these challenges. Material cost and scarcity of elements in state-of-the-art thermoelectric materials are current limitations. Conductive polymers has become an attractive alternative to those materials, however they suffer from low Seebeck coefficient. Nanoscale composites of inorganic semiconductors with conductive polymers could improve low Seebeck coefficients and power factors of conductive polymers, however quantitative understandings on the mechanisms lying behind the enhancements were often missing. In our research, thin film heterostructures of a conductive polymer, PEDOT:PSS / undoped Si or undoped Ge were selected as templates for mechanistic investigations on thermoelectric performance enhancements. With the combination of experiments and simulation, it was determined that p-type PEDOT:PSS transferred holes to the interfaces of adjacent Si and Ge, and these holes could take advantage of higher hole mobility of Si and Ge. This phenomenon called modulation doping, was responsible for thermoelectric power factor enhancements in Si / PEDOT:PSS and Ge / PEDOT:PSS heterostructures. Another technology to transform low-grade heat into electricity is electrochemical heat conversion. Traditionally, the electrochemical heat conversion into electricity suffered from low conversion efficiency originating from low ionic conductivity of electrolytes, even though high thermopowers often reaching several mV/K has been an alluring advantage. Recently developed breakthrough on operating such devices under thermodynamic cycles bypassed low ionic conductivity issue, thereby improving the conversion efficiency by multiple orders of magnitude. In this study, we focused on improving efficiency by increasing thermopowers and suppressing heat capacity of the system, while maintaining the autonomy of thermodynamic cycles without need for recharging by external sources of electricity. These detailed interpretations on nanoscale composite thermoelectric systems and electrochemical heat harvester provide insights for the design of next-generation thermoelectric and electrochemical heat energy harnessing solutions. / by Dongwook Lee. / Ph. D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1990. / Includes bibliographical references (leaves 177-182). / by Chun Dong. / Ph.D.