Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / Microfiche copy available in Archives and Science. / Bibliography : leaves 414-426. / by Lucile M. Shanes. / Ph.D.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Vita. / Bibliography: leaves 73-77. / Ph.D.

This thesis describes several molecular dynamics studies of polymers, proteins, and active colloids. These diverse systems fall under the purview of soft matter physics and in Part I, I explain what is soft matter and describe some of its essential features. In Part II, I introduce some basic polymer physics and show how confined polymers can be described using blob theory. I also discuss how phase separation of polymer mixtures can occur. These concepts are applied to systems of mixed polymer brushes on spheroids, objects that have surfaces with non-uniform curvature. I show how the interplay of phase separation and surface curvature give rise to striped patterns, and how an extension of blob theory can give analytical expressions for the free energy. Finally, I show how phase separation of miscible polymers can occur, driven solely by surface curvature. In Part III, I present an overview of self-assembly and describe how active, or self-propelled colloids can be used to assemble new materials. I show how two large colloids immersed in a bath of smaller active colloids exhibit an effective short-ranged repulsion and long-ranged attraction, which stands in contrast to the standard short-ranged depletion attraction. I also explore how self-propulsion changes clustering by focusing on a system with short-ranged attractive and long-ranged repulsive particles, which under equilibrium, exhibit finite-sized clusters. I show that for certain parameters, spheres can form a fluid of living crystals, and dumbbells can form a crystal of rotors. In Part IV, I give a brief introduction to protein folding and describe how molecular chaperones combat misfolding in the human body. Then, taking inspiration from the chaperones, I show that a polymer-grafted “soft” nanopore can be used to unfold misfolded proteins and destroy undesired aggregates. I also show preliminary results for a hydrophobic “smart” nanopore that can selectively capture and unfold misfolded proteins.

Cheng Kwok Kei = 高分子電解質-膠體複合體系的相互作用和極化率 / 鄭國基. / Thesis submitted in: November 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 68-73). / Text in English; abstracts in English and Chinese. / Cheng Kwok Kei = Gao fen zi dian jie zhi-jiao ti fu he ti xi de xiang hu zuo yong he ji hua lü / Zheng Guoji. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Polyelectrolyte Colloid Complex --- p.1 / Chapter 1.2 --- Image charges --- p.3 / Chapter 1.3 --- Objective of the thesis --- p.3 / Chapter 2 --- Equations for induced image charges (Review) --- p.5 / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Image effect --- p.6 / Chapter 2.2.1 --- The potential --- p.6 / Chapter 2.2.2 --- Surface charge density --- p.8 / Chapter 2.2.3 --- Potential energy --- p.9 / Chapter 3 --- Polarizability of a polyelectrolyte colloid complex --- p.11 / Chapter 3.1 --- Introduction --- p.11 / Chapter 3.2 --- The Simulation Model --- p.12 / Chapter 3.2.1 --- Energy of the Complex --- p.13 / Chapter 3.2.2 --- Dipole of the Complex --- p.15 / Chapter 3.2.3 --- Thermal Energy --- p.18 / Chapter 3.3 --- Calculating Method --- p.18 / Chapter 3.3.1 --- Monte Carlo Simulation --- p.19 / Chapter 3.3.2 --- Partition Function Calculation --- p.20 / Chapter 3.4 --- Polarizability --- p.22 / Chapter 3.4.1 --- Compare polarizability of the complex with a permanent dipole --- p.22 / Chapter 3.4.2 --- Results and Discussion --- p.23 / Chapter 3.5 --- Effect of image charges for the complex --- p.33 / Chapter 3.6 --- Conclusion --- p.37 / Chapter 4 --- Correlation and Interaction of complexes - without induced charges --- p.38 / Chapter 4.1 --- Introduction --- p.38 / Chapter 4.2 --- The Simulation Model --- p.39 / Chapter 4.2.1 --- Energy of the system --- p.40 / Chapter 4.2.2 --- Dipole Moment --- p.42 / Chapter 4.3 --- Results and Discussion --- p.43 / Chapter 4.3.1 --- Polarizability of complex --- p.43 / Chapter 4.3.2 --- Correlations between two complexes --- p.46 / Chapter 4.3.3 --- Potential of mean force --- p.50 / Chapter 4.4 --- Conclusion --- p.52 / Chapter 5 --- Correlation between Two Complexes - with induced charges --- p.53 / Chapter 5.1 --- Introduction --- p.53 / Chapter 5.2 --- Induced Surface Charges --- p.54 / Chapter 5.2.1 --- Surface charges --- p.54 / Chapter 5.2.2 --- Energy of system --- p.55 / Chapter 5.2.3 --- Dipole Moment --- p.57 / Chapter 5.3 --- Results and Discussion --- p.58 / Chapter 5.3.1 --- Polarizability of complexes --- p.59 / Chapter 5.3.2 --- Correlation between two complexes --- p.61 / Chapter 5.3.3 --- Potential of mean force --- p.63 / Chapter 5.4 --- Conclusion --- p.64 / Chapter 6 --- Summary --- p.66 / Bibliography --- p.68 / Chapter A --- Mathematical calculation of the dipole moment of a complex --- p.74 / Chapter A.1 --- Equation of mean squared dipole --- p.74 / Chapter A.2 --- z-component of dipole and squared dipole --- p.76

Shi Lei = 溶凝膠分佈反饋波導激光器之光學性質的研究 / 石蕾. / "September 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 150-171) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese. / Shi Lei = Rong ning jiao fen bu fan kui bo dao ji guang qi zhi guang xue xing zhi de yan jiu / Shi Lei.

In our research Hyper-Rayleigh scattering (HRS) is employed as an effective, simple investigation technique to study solutions of small molecules, pure liquids, nano-adsorbing systems and metal colloids. A set of apparatus has been built with good spectral resolution and high sensitivity to successfully measure characteristics of intensity and polarization properties of HRS. It was found that the consistency was different for pure liquid and solutions of small molecules when comparing experimental measurements of depolarized ratios and polarization patterns with theoretical expectations. This is due to the presence of both incoherent and coherent contributions to HRS in pure liquids, of which the origin of the coherent contribution is different for different pure liquids. In our results, pure liquid nitrobenzene was found to have strong coherent contribution to HRS caused by intermolecular interactions. Three different chemical compounds were used to mix with nitrobenzene to break the strong orientational correlations between molecules. Comparison between the results show different behaviors in the effectiveness in eliminating the coherent HRS signals, and the effectiveness was correlated to the molecular structures. Theory of second harmonic scattering from surface has been expanded as leading order contributions containing nonlocal electric dipole mode and local quadrupole mode, which can be exhibited in our experimental study of polarization patterns. Polarization patterns from polystyrene particles of different sizes adsorbed with different species of dyes were measured to investigate and compare with theoretical expectations. For small-size adsorbing system, measurements of polarization patterns were basically consistent with theory. However, for adsorbing system of polystyrene particles with a size of 900 nm, the polarization patterns showed discrepancies when comparing with theory, which indicated that higher order multipoles are needed in the theory. Silver and gold colloids were employed as the subject of investigation for measuring the polarization patterns of HRS. The results were found to be consistent when comparing with their extinction spectra and TEM images. We have managed to measure polarization patterns of HRS originated from surface of non-spherical colloids and the results showed that the origin of HRS can be qualitatively understood, although a more elaborated theory is needed to describe the data. / by Chen, Ji = 由有機液體以及金屬膠體產生的非線性光散射的研究 / 陳佶. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 117-118). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307. / by Chen, Ji = You you ji ye ti yi ji jin shu jiao ti chan sheng de fei xian xing guang san she de yan jiu / Chen Ji.

Zhu Xiao Lei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 116-121). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Xing, Xiaochen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstract also in Chinese. / Abstract (Chinese) --- p.i / Abstract --- p.iii / Contents --- p.v / Acknowledgement --- p.ix / Chapter Chapter1 --- Introduction and background / Chapter 1.1 --- Overview of Studies in Colloid-Polymer mixture --- p.1 / Chapter 1.2 --- Depletion Force in Colloid-Polymer Mixture --- p.1 / Chapter 1.2.1. --- Depletion Interaction in Monodisperse and Neutral Polymer-Colloid Mixtures: Theory --- p.3 / Chapter 1.2.1.1. --- An Exact Result: the Interaction between Parallel Plates due to Ideal Polymer Chains --- p.3 / Chapter 1.2.1.2. --- Penetrable Hard Sphere (PHS) Approach --- p.4 / Chapter 1.2.2. --- Early Experimental Findings of Depletion Interaction --- p.6 / Chapter 1.3 --- References and Notes --- p.8 / Chapter Chapter2 --- Principle of Total Internal Reflection Microscopy (TIRM) and Instrumentation / Chapter 2.1 --- Introduction of Total Internal Reflection Microscopy (TIRM) --- p.10 / Chapter 2.2 --- The Principle of TIRM Technique --- p.11 / Chapter 2.2.1 --- Total Internal Reflection --- p.11 / Chapter 2.2.2 --- Details on Scattering of the Evanescent Wave --- p.13 / Chapter 2.2.3 --- Data Analysis --- p.16 / Chapter 2.3 --- Instrumentation --- p.20 / Chapter 2.3.1 --- Apparatus --- p.20 / Chapter 2.3.2 --- Optical Tweezer --- p.23 / Chapter 2.3.3 --- Cleaning of the Slide Surface --- p.24 / Chapter 2.3.4 --- A Typical Potential Energy Profile --- p.25 / Chapter 2.4 --- Laser Light Scattering (LLS) --- p.26 / Chapter 2.5 --- Zeta-potential Measurements --- p.27 / Chapter 2.6 --- References and Notes --- p.28 / Chapter Chapter3 --- Depletion Attraction between a Polystyrene Sphere and a Hydrophilic Surface in a Pluronic Aqueous Solution / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Experimental Section --- p.34 / Chapter 3.2.1 --- Sample Preparation --- p.34 / Chapter 3.2.2 --- Total Internal Reflection Microscopy --- p.35 / Chapter 3.2.3 --- Laser Light Scattering --- p.36 / Chapter 3.3 --- Results and Discussion --- p.37 / Chapter 3.4 --- Conclusion --- p.48 / Chapter 3.5 --- References and Notes --- p.50 / Chapter Chapter4 --- pH-Controllable Depletion Attraction Induced by Microgel Particles / Chapter 4.1 --- Introduction --- p.53 / Chapter 4.2 --- Experimental Section --- p.54 / Chapter 4.2.1 --- Sample Preparation --- p.54 / Chapter 4.2.2 --- Total Internal Reflection Microscopy --- p.56 / Chapter 4.3 --- Results and Discussion --- p.58 / Chapter 4.4 --- Conclusion --- p.63 / Chapter 4.5 --- References and Notes --- p.64 / Publication List --- p.65

The backbone of the industrialized world is comprised of refined, zerovalent metal, a material which thermodynamically favors an oxidative return to more chemically stable states. There are many methods used to slow or delay this process, such as protective coatings, sacrificial anodes, and alloys, but no method can entirely prevent corrosion. This body of work instead proposes detecting the earliest chemical markers of corrosion: that is, metal ions as they solubilize from a metal surface. Such information would allow maintenance personnel to make informed decisions about the necessity or lack thereof of preventive maintenance, and intervene before advanced damage has a chance to occur. This dissertation finds that hydrogel-based sensors are capable of such detection and offer a multisensory response, with colorimetric, electrical, volumetric and vibrational changes. Both the colorimetric and electrical trends were calibrated and used for quantification of metal ions both in solution and directly from metal substrate surfaces. Observing how the hydrogels responded to various metal ions contributed to a greater understanding of how ion-headgroup associations can affect the sensory responses of a hydrogel, something that can be exploited in future sensor work. The ability of the sensors to detect ions directly from metal surfaces allowed for an investigation of the protective quality of fatty acids as corrosion inhibitors. A range of chain lengths were tested using the hydrogels, and the comparison to current characterization techniques showed good correlation. This accessible technique, beyond contributing to the current meager literature of fatty acids as corrosion inhibitors, can also allow for the determination of acceptable benchmarks of corrosion, information that is sorely needed to efficiently steward global infrastructure.

The purpose of this study was to prepare concentrated and stable gold colloids for the enhancement of the signal response of the SPR technique for detecting small molecules such as progesterone. The gold colloids developed in this study were prepared by hydrazine hydrate, sodium borohydride, and tri-potassium citrate reduction routes. The study revealed that the sodium borohydride reduced gold colloids were extremely stable and it was able to be utilised in the progesterone immunoassay developed previously by Mitchell et al. The experiment was carried out on BIAcore 3000 using two different sensor surfaces (CM5 and SAM). The results showed that the enhancement species prepared from the borohydride-reduced gold colloids were able to improve the SPR signal response by 13 times higher than SPR signal produced without the enhancement species on the CM5 surface. The signal enhancement on the SAM surface using the same enhancement species was even greater at 29 times higher. The sensitivity of the assay was, however, unable to be determined due to time constraint. The limit of detection (LOD) of the progesterone assay using the CM5 chip was estimated to be ca. 5-20 pg/mL. Whilst for the SAM chip, the LOD of the progesterone assay was estimated to be ca. 5-20 fg/mL. Further work is required to confirm these estimated LOD values.