Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994. / Includes bibliographical references (p. 37). / by William Giacomo Fonte. / M.S.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1997. / Includes bibliographical references (leaf 38). / by Matthew Craig Neumann. / B.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008. / Includes bibliographical references (p. 33-34). / Photolithography of a pH-sensitive photoresist polymer was performed to pattern both lipid bilayers and proteins onto the same surface. The motivation behind this was to create a substrate mimicking an array of antigen- presenting cells. The substrate would consist of signaling ligand, biotin anti- CD3, bound to a lipid bilayer in a regular array of patches. The fluidity of the lipid bilayer would impart mobility to the signaling ligand. It was found that under appropriate substrate fabrication conditions, lipid bilayers and their associated ligand do segregate to the desired signaling patches. Additionally, the bilayer in these regions is fluid, and is potentially bioactive. This bodes well for our system as a future platform to study the actions of the helper T cell and antigen- presenting cell at the immunological synapse. / by Mirat Shah. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012. / "September 2012." Cataloged from PDF version of thesis. / Includes bibliographical references (p. 65-66). / In the as-deposited state, thin films are generally far from equilibrium and will agglomerate or dewet to form arrays of islands when sufficient atomic motion is allowed. Dewetting can occur well below the films' melting temperature in the solid-state. The dewetting process begins by formation and motion of film-substrate-vapor three-phase boundaries. These film edges retract via capillarity-driven mass transport. In the absence of film or substrate patterning, the dewetting morphology of polycrystalline films is not well ordered. However, dewetting in single crystal films leads to a much more regular morphology, due to surface and interfacial energy anisotropy and surface self-diffusivity anisotropy. When dewetting of such films is templated by pre-patterning, dewetting patterns much smaller than the original template patterns can be generated. This makes templated dewetting a potential self-assembly method for generation of complex structures with sub-lithographic length scales. However, control of such patterns in single crystal films requires a significant degree of quantitative understanding of anisotropic dewetting in the solid-state. As a starting point for quantitative research on solid-state dewetting of single crystal films, dewetting of thin single crystal films that were pre-patterned to have edges with specific in-plane orientations were quantitatively characterized and their observed behavior was modeled. Edges aligned to specific crystallographic orientations remain straight as they retract, while edges with other crystallographic orientations develop in-plane facets composed of kinetically stable edges. Therefore, a quantitative understanding of the retraction of kinetically stable edges can serve as the basis for understanding the retraction of edges with all other orientations. Measurements of the rates of retraction of kinetically stable edges for single crystal (100) and (110) Ni films on single crystal MgO are reported. In cross section, the retracting edges develop out-of-plane facets that are generally consistent with the facets expected from the equilibrium Wulff shape. To capture the observed anisotropic character of the edge retraction rate, capillarity-driven edge retraction through atomic surface self-diffusion was modeled in 2 dimensions using the crystalline formulation method developed by Carter and coworkers. The model and experiments show a similar time scaling for the edge retraction distance. Also, the magnitudes of the predicted retraction rates are consistent with the specific observed retraction rate anisotropy given the large range of error in parameters used in the model. Other possible sources of error include the fact that actual edges are not fully facetted and are sometimes bound by non-equilibrium facets. / by Gye Hyun Kim. / S.M.

Thesis: S.B., 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 (page 41). / Patterned media on the nanometer scale are useful for electrical, optic, and magnetic applications such as memory storage. Using block copolymer fabrication methods, 60nm diameter cobalt nanodots and 37nm wide cobalt nanowires were created, both with heights of 20nm. To characterize the reliability of the nanodots, magnetic hysteresis loops of three samples, Co5 Co7 and Co9, were taken at elevated temperatures up to 350°C Comparing room temperature magnetization to the ideal magnetization, percent of surface covered in nanodots was calculated to be 88%, 50%, and 60% respectively for each sample. The trends of magnetization per square centimeter and coercivity with temperature both suggest 2 mechanisms are involved in decreasing the magnetic properties of the nanodots; oxidation occurring below 200°Cand microstructure rearrangement occurring above 200°C The depth of oxide growth on the nanodots was calculated to be 2nm deep on the surface of the nanodots when below 200°Cand no more than 10nm deep when above 200°C Activation volume calculations could not be accurately calculated, suggesting an activation volume 10!! times the volume of one nanodots. To characterize magnetic features present in the nanowires from block copolymer fabrication, magnetic force microscopy images were taken of direct and alternating demagnetized samples for a qualitative analysis. Counting magnetic features showed direct demagnetized samples had more 50% domain walls, with the domain walls mainly located on junctions and curves. Alternating demagnetized samples had fewer domain walls and these were predominantly located in straight lines. / by Juan J. Hernandez. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994. / Includes bibliographical references (leaves 72-74). / by Takeshi Sugiyama. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994. / On t.p., "[delta]" appears as the lower case Greek letter, in subscript. Vita. / Includes bibliographical references (p. [67]-69). / by Michael W. Daniels. / M.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 39). / The endosome-disrupting and pH-responsive poly(2-diethylamino ethyl methacrylate)-core/poly(2- aminoethyl methacrylate)-shell nanoparticles could potentially increase the efficacy of transcutaneous administered vaccines and facilitate the cytosolic delivery of a wide variety of therapeutic macromolecules. One of the goals of this study was to reduce the size of these core-shell nanoparticles to improve their permeation into the skin. Separate nanoparticle syntheses using reduced durations, decreased monomer concentrations, and decreased monomer solubility did not cause a significant decrease in the particle diameter compared to those previously reported. Manipulation of the reaction kinetics did not stabilize smaller particles leaving them susceptible to coagulation. Synthesis of poly(2-diethylamino ethyl methacrylate)/ Poly(ethylene glycol) methacrylate copolymer nanoparticles were sterically stabilized by the amphiphilic polymer brush at the particle surface and exhibited slightly smaller hydrodynamic diameter measured by dynamic light scattering. Manipulation of the reaction kinetics and the monomer ratio could lead to significantly smaller chains. Another goal for this study was to create core-shell nanoparticles with different charged shells to see if the shell could be modified to electrostatically adsorb a wider range of drugs. In addition, the different charges of the shell could affect the nanoparticles' endosome-disrupting abilities and/or their permeation through the skin. / (cont.) Surprisingly, the zeta-potential measurements were the same for each sample though the shells were supposed to have different charges. This suggests that surface charge density of the PDEAEMA core was being measured. When nanoparticles with a smaller PDEAEMA core and a thicker PAEMA shell were synthesized, a change in the zeta potential was observed that was consistent with the larger positive surface charge density and the higher pKb of the PAEMA shell. This suggests that the adsorption of positively charged drugs may be difficult because it would require negatively charged shell that is thick enough to counteract the positive PDEAEMA core. / by Jason S Pellegrino. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 89-91). / A diode laser emitting at mid-infrared wavelength (2~5 pm) is an ideal light source for petrochemical or industrial-important gas sensing. Antimony-based III-V compound semiconductor material is the most prominent pseudomorphic epitaxy candidate for this application. However, phosphide-based material not only has the potential to reach this wavelength utilizing a strained active region but also takes the advantage of sophisticated material study from telecommunication technology. This thesis presents the realization of a 1.97 pm emission ridge waveguide laser in design, fabrication, and characterization phases. Ino.85 Gao.15As/Alo.1Ino.4 8Gao.42As strained multiple quantum wells structures have being built on InP substrates. Structural, optical, and electrical properties of the material have being tested and summarized. / by Pei-Chun Chi. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007. / Includes bibliographical references (leaves 161-170). / Cartilage, particularly its collagen network, has been suggested by many to be fatigue prone, but the mechanism via which fatigue damage occurs is not yet well-understood. This work seeks to provide a simple framework to further our understanding of the degeneration of this tissue a result of fatigue damage via experimentation and analytical modeling. It was as observed that subjecting initially intact bovine tibial plateau cartilage to repeated long-term applications of an indentation loading protocol, which does not induce any observable damage over a single short-term application, can result in surface damage. The damage can be associated with an increase in the GAG release and decrease in the tissue nominal equilibrium modulus. The ability of the tissue to regain its original configuration also deteriorated with increasing number of loading cycles, but the change was generally gradual. Changes in the optimized parameters obtained from fitting a 1-D rheological model to both the relaxation and cyclic loading responses of cartilage in the undamaged and damaged states suggested that both GAG and collagen have been weakened as a result of damage. A portfolio of data describing the 3-D mechanical behavior of calf tibial plateau cartilage was obtained in this work. It was found that both the axial and lateral responses of cartilage were nonlinear during stress relaxation. Also, the resistance of the tissue to shear and volumetric deformation is dissipative, with the same time constants. / (cont.) Finally, differences in the extra- and sub-meniscal tissue were noted. A structurally-based constitutive model that was originally formulated for cervical stroma was employed in this work in attempt to capture the mechanical response of cartilage. It was found able to capture the axial and lateral responses of cartilage in unconfined compression at 20% nominal strain. Changes in the material parameters obtained from fitting the constitutive model to the indentation responses of cartilage in the native and damaged states suggested that damage has induced alterations in both GAG and collagen, echoing our earlier findings. / by Bruce Y.C. Wu. / Ph.D.