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NPLIN was studied in supersaturated solutions (S = 1.06) of potassium chloride (KCl) and bromide (KBr). The fraction of samples nucleated (f) follows a nonlinear dependence on peak power density that approaches f = 1 at higher incident powers. It is shown that a lower threshold power is required for nucleation using 532 nm laser pulses than at 1064 nm, and that a higher fraction of samples nucleate when exposed to 532 nm pulses at a given laser power. Comparison with KCl shows higher fractions of KBr samples nucleate with lower threshold values at both wavelengths. Samples of KCl of equal supersaturation at two different temperatures (23 and 33 °C) exposed to 1064 nm pulses show that those at 33 °C are significantly more labile to nucleation. The ratio of samples nucleated at 33 °C compared to those at 23 °C was 2.11 ± 0.47. A classical nucleation model based on activation of subcritical solute clusters accounts remarkably well for the experimental data and provides phenomological values of the crystal–solution interfacial tension (γ) at 23 °C for KCl and KBr of 5.283 and 4.817 mJ m-2. At 33 °C, the model yields a best-fit value of γ = 5.429 mJ m-2 for KCl. As an extension of this work the use of an evanescent wave (ew) generated by total internal reflection was investigated as a method to cause nucleation in supersaturated KCl solution. Evanescent wave NPLIN (ew-NPLIN) was shown to cause nucleation. The results showed a higher laser-power threshold required for nucleation and sample lability greater than that of bulk NPLIN. In a second approach to understanding NPLIN, the structures of concentrated solutions were probed by a series of laser scattering experiments. Evidence showing populations of particles in solution was provided by Rayleigh laser scattering (RLS) experiments. Scattering in solutions prepared to be nearly saturated (S = 0.95) was observed using a low magnification (×10) microscope objective; almost all solutions showed the presence of scattering objects moving freely in solution. For those that showed no particles, it was noted that the solutions were typically of higher solute concentration (> 11 mol% solute). Ammonium nitrate solution showed no particles using ×10 magnification, however particles were identified when higher magnification was used (×50 and ×100). Video footage of the Rayleigh scattering observed in aqueous solutions of glycine, urea and ammonium nitrate obtained using ×50 magnification were analysed using a custom nanoparticle tracking software. The results showed a population of particles in aqueous urea and glycine solutions with particle concentrations of the order 108 particles cm-3 and mean hydrodynamic diameter of approximately 267 ± 1 and 173 ± 2 nm respectively. Not enough particles were identified in ammonium nitrate solution to complete the tracking analysis; however a fluctuating background scatter suggested a population of particles with sizes below the limit of resolution of the optical system. Using aqueous urea solution as a model system the structure of the particles identified in solution was investigated using scanning microscopy. The second-harmonic scattering (SHS) signal measured in concentrated aqueous urea solution was measured as a function of solution concentration (C) over a range of saturation conditions from undersaturated (S = 0.15) to supersaturated (S = 1.86). The results show a non-linear increase in SHS signal with local maxima near S = 0.95 and 1.75 suggesting a change in solution structure near these points. Rayleigh scattering images indicate the presence of particles in nearly saturated (S = 0.95) urea solutions. Time-dependent SHS measurements indicate that signals originate from individual events encountered during scanning of the sample through the focal volume of the probe laser, consistent with second harmonic generation (SHG) from particles. SHG from aqueous dispersions of barium titanate (BaTiO3) nanoparticles with diameters < 200 nm, showed signals ~20 times larger than urea solutions. The results suggest the existence of a population of semi-ordered clusters of urea that changes with solution concentration.

by Wai Ming Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 71-74). / ACKNOWLEDGEMENTS --- p.i / CONTENTS --- p.ii / ABSTRACT --- p.iv / Chapter I. --- INTRODUCTION --- p.1 / Chapter I-1. --- Liquid Crystal Mesophases --- p.1 / Chapter I-1-1. --- Mesophases --- p.1 / Chapter I-1 -2. --- Classification of liquid crystals according to molecular order --- p.1 / Chapter I-2. --- Ferroelectric Liquid Crystals --- p.6 / Chapter I-3. --- "The Relationship Among Spontaneous Polarization, Tilted Angle and Response Time" --- p.7 / Chapter I-4. --- Applications of Liquid Crystals --- p.8 / Chapter I-5. --- An Ideal Ferroelectric Liquid Crystal --- p.9 / Chapter I-6. --- Recent Development in Chiral Liquid Crystals --- p.10 / Chapter I-7. --- Aim of The Present Research: Chiral Liquid Crystals from Carbohydrates --- p.15 / Chapter II. --- RESULTS AND DISCUSSION --- p.17 / Chapter II-1. --- "Synthesis of 4',4""-Heptoxybiphenyl (methyl 2-O-n- butyl-3,4-dideoxy-a-D-glucopyranosid) uronate (12) and 4',4""-Cyanobiphenyl (methyl 2-O-n-butyl -3,4-dideoxy-a-D-glucopyranosid) uronate (13)" --- p.17 / Chapter II-2. --- "Synthesis of 4',4''-Heptoxybiphenyl (methyl 2-O-n- butyl-3,4-di-O-methyl-a-D-glucopyranosid) uronate (14) and 4' ,4""-Cyanobiphenyl (methyl 2-O-n-butyl -3,4-di-O-methyl-α-D-glucopyranosid) uronate (15)" --- p.33 / Chapter II-3. --- Mesomorphic Phases and Transition Temperatures of Chiral Liquid Crystalline Compounds 12 and 13 --- p.42 / Chapter III. --- CONCLUSION --- p.47 / Chapter IV. --- EXPERIMENTAL SECTION --- p.48 / Chapter V. --- REFERENCES --- p.71 / List of Spectra --- p.75 / Spectra --- p.76

by Qian Wang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 107-111). / Acknowledgements --- p.i / Contents --- p.ii / Abstract --- p.iv / Chapter I. --- Introduction --- p.1 / Chapter II. --- Results and Discussion --- p.23 / Chapter II-1. --- "Stereoselective Synthesis of Chiral Liquid Crystalline Compounds Containing a 1,4-Disubstituted Cyclohexene Ring" --- p.23 / Chapter II-1-1. --- "Synthesis of (S)-(-)- and (R)-(+)-4'-(4""-Cyanobiphenyl) 4-Pentyl-3-cyclohexene-1-carboxylate (1 and 3) and (S)-(-)-4'-(4""-Octoxybiphenyl) 4-Pentyl-3-cyclohexene-1-carboxylate (2)" --- p.23 / Chapter II-1-2. --- "Synthesis of (S)-(-)-4'-(4""-Cyanobiphenyl) 4-Butoxymethyl-3-cyclohexene-1-carboxylate (4)" --- p.35 / Chapter II-1-3. --- "Synthesis of (S)-(-)- and (R)-(+)-4'-(4""-Heptoxybiphenyl) 4-(2-Propenyl)-1-cyclohexene-1-carboxylate (5 and 7) and (S)-(-)- and (R)-(+)-4'-(4""-Octoxybiphenyl) 4-(2-Propenyl)-1-cyclohexene-1-carboxylate (6 and 8)" --- p.37 / Chapter II-2. --- "Synthesis of Chiral Liquid Crystalline Compound Containing a trans-2,5-Disusbstituted Cyclohexanone Ring´ؤ(1S,4S)-4'-(4""-Heptoxybiphenyl) 4-Penyl-3-cyclohexanone-1-carboxylate (9)" --- p.42 / Chapter II-3. --- "Determination of Enantiomeric Purities of (S)-(-)- and (R)-(+)-Perillalcohols (17 and 28), (S)-(-)- and (R)-(+)-1-Pentyl-4-hydroxymethyl-l-cyclohexenes(35 and 36), and (2S,5S)-2-Pentyl-5-hydroxymethyl-l-cyclohexanone (64)" --- p.58 / Chapter II-3-1. --- Determination of Enantiomeric Purities of (S)-(-)- and (R)-(+)-Perillalcohols (17 and 28) --- p.58 / Chapter II-3-2. --- Determination of Enantiomeric Purities of (S)-(-)- and (R)-(+)-1-Pentyl-4-hydroxymethyl-1-cyclohexenes (35 and36) --- p.64 / Chapter II-3-3. --- "Determination of Enantiomeric Purity of (2S,5S)-2-Pentyl-5-hydroxymethyl-1 -cyclohexanone (64)." --- p.67 / Chapter II-4. --- "Mesomorphic Phases and Transition Temperatures of Chiral Liquid Crystalline Compounds 2, 3, 5, 6, 7, 8 and 9" --- p.72 / Chapter III. --- Conclusion --- p.77 / Chapter IV. --- Experimental --- p.78 / Chapter V. --- References --- p.107 / List of Spectra --- p.112 / Spectra --- p.116

"Composites of nanoparticles with complex fluids represent a unique physical system where thermal physical properties of the components partially or fully mix and new behavior can emerge. Traditional composites are relatively well understood as the superposition, weighted by volume or mass, of the components properties and the interfacial interactions play the role of holding the composite together. As the filler component, nanoparticle, decreases in size, the surface area begins to dominate, leading to unique behavior of the nanocomposites. The richness of the nanocomposites that can be designed by coupling various nanoparticles and complex fluid materials opens a wide field of active research. This dissertation presents a series of experimental studies on various nanocomposites using modulated differential scanning calorimetry, spectroscopic ellipsometry, dielectric spectroscopy, polarizing microscopy, and conductivity measurements of nanoparticles such as multi-wall carbon nanotubes and quantum dots on the phase transitions of several liquid crystals and polymers. The liquid crystals (LCs) and liquid crystalline polymer (LCP) of interest are: negative dielectric anisotropy alkoxyphenylbenzoate (9OO4), octylcyanobiphenyl (8CB), decylcyanobiphenyl (10CB), and isotactic polypropylene (iPP) which can form smectic liquid crystal (LC) phase. Studies have been carried out as a function of concentration and temperature spanning through various ordered phases. The results indicate a mixture of ordering and disordering effects of the nanoparticles on the phases of the complex fluids. In 9OO4/CNT system, dipole moment of liquid crystal and graphene like surface can allow a random dispersion of CNT to promote both orientational and positional order. For nCB/CNT, nCB/Quantum dot (QD) systems, nanoparticles induce net disordering effect in LC media. The effect of QDs on LC depends on the anchoring conditions and the QDs size. The results clearly demonstrate that the nematic phase imposes self-assembly on QDs to form one dimensional arrays. This leads to net disordering effect. The thermal/electrical conductivity changes in thin films of iPP/CNT sheared/un-sheared samples and it also varies with temperature for the purpose of inducing anisotropy of those properties in parallel and perpendicular to average orientation. The percolation threshold is clearly pronounced in both conductivities due to pressing and shearing treatment of the films. This will further our abilities to nano-engineer material for many important applications."

Extreme climate change and demanding energy resources have led to new geotechnical engineering challenges critical for sustainable development and resilient infrastructure of our society. Applications such as geological disposal of nuclear waste and carbon dioxide, artificial ground freezing, and hydraulic fractures all require an in-depth understanding of the thermo-hydro-mechanical coupling mechanisms of geomaterials subjected to various environmental impact. This dissertation presents a multiphysical computational framework dedicated to address the issues related to those unconventional applications. Our objective is not only incorporating multiphysical coupling effects at the constitutive laws, but also taking into account the nonlocal effects originated from the flow of pore-fluid, thermal convection and diffusion among solid and fluid constituents, and crystallization and recrystallization of crystals in the pore space across length scales. By considering these coupling mechanisms, we introduce a single unified model capable of predicting complex thermo-hydro-mechanical responses of geological and porous media across wide spectra of temperature, confining pressure and loading rate. This modeling framework applies to two applications, i.e., the freezing and thawing of frozen soil and the modeling of anisotropic crystal plasticity/fracture response of rock salt. Highlights of the key ingredients of the models cover the stabilization procedure used for the multi-field finite element, the return mapping algorithm for crystal plasticity, the micromorphic regularization of the Modified Cam-Clay model, and the strategy for enhancing computational efficiency of solvers, such as pre-conditioner, adaptive meshing, and internal variable mapping. By introducing the multiphysical coupling mechanisms explicitly, our computational geomechanics model is able to deliver more accurate and consistent results without introducing a significant amount of additional material parameters. In a parallel effort, we analyze the impact of thermo-hydro-mechanical (THM) coupling effects on the dynamic wave propagation and strain localization in a fully saturated softening porous medium. The investigation starts with deriving the characteristic polynomial corresponding to the governing equations of the THM system. The theoretical analysis based on the Abel–Ruffini theorem reveals that the roots of the characteristic polynomial for the THM problem cannot be expressed algebraically. Our analysis concludes that the rate-dependence introduced by multiphysical coupling may not regularize the THM governing equations when softening occurs.