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Surface-enhanced Raman scattering (SERS), as a promising analytical tool, has been widely used due to the finger-print spectra of the molecular vibrations and the enhancement of signals between hotspots. In this dissertation, different synthesis methods of noble metal-containing nanoparticles have been explored and SERS applications of these nanoparticles in environmental and biological fields have been illustrated. In the first project, trichloroethylene (TCE) in environmental water was determined by SERS quantitatively. Au-core/Ag-shell nanoparticles with 4-mercaptophenylboronic acid (4-MPBA) embedded as internal reference were used as SERS substrates. TCE has little Raman signal, but it can react with 4-mercaptopyridine (4-MPy) through Fujiwara Reaction. 4-MPy was used as the SERS analyte, and the consumption of 4-MPy with the presence of TEC resulted in the intensity change of 4-MPy Raman signal at 1220 cm-1. The 4-MPBA signal at 534 cm-1 was used as an internal reference to normalize 4-MPy signal. The intensity ratio of 4-MPy/4-MPBA linearly decreased when the concentration of TEC increased between 0.2 and 1.0 µM. The detection limit of TCE was 8 ppb and this method was applied to detect TCE in spiked lake water successfully.In the second project, SERS was used as an analytical tool to detect polycyclic aromatic hydrocarbons (PAHs) in environmental soil. ß-cyclodextrin was conjugated to 4-MPBA modified gold nanoparticles to capture and bring the hydrophobic PAHs closer to the surface of gold nanoparticles. Pyrene and anthracene were used as the model PAHs, and 4-MPBA was used as an internal reference. The intensity ratio of pyrene/4-MPBA (580 cm-1/1570 cm-1) was linear in the 2 to 10 nM concentration range and the intensity ratio of anthracene/4-MPBA (750 cm-1/1570 cm-1) was linear in the 10 to 100 nM concentration range. This method was applied to determine pyrene and anthracene in a soil sample and the results had a good recovery when compared to the conventional GC-MS results. In the third project, the detection of single-stranded BRAF V600E mutation DNA showed the feasibility of SERS application in the biological field. Au-coated magnetic nanoparticles with 6-mercaptopyridine-3-carboxylic acid (MPCA) (MNP@SiO2@Au-MPCA) and silver nanoparticles with 4-mercaptobenzonic acid (4-MBA) (Ag@4-MBA) were used as SERS substrates. Rationally designed DNA probes were conjugated to the SERS substrates. With the presence of the single-stranded DNA containing BRAF V600E mutation, it hybridized with the DNA probes and brought the Ag@4-MBA close to the MNP@SiO2@Au-MPCA. The adjunctive DNA probes were ligated under Taqligase through thermal cycles and the resulted nanoparticles were separated easily by a strong magnet. The intensity of the 4-MBA Raman signal indicated the amount of target DNA in the system, and MPCA was used as an internal reference. The intensity ratio of 4-MBA/MPCA was linear in the 1-100 fmol range of the BRAF mutation DNA. Different ratios of BRAF mutation/BRAF normal from 0.02-1% were used to mimic real samples and a good linear regression of the intensity ratio of 4-MBA/MPCA in this range demonstrated the potential for clinical use.

Multiphase flows involving bubbles and droplets are ubiquitous in nature and in many industrial processes. Detailed information of such flows can be acquired from direct numerical simulations that directly resolve the flow on the bubble or droplet scale. In recent years, the lattice Boltzmann method (LBM) has emerged as a novel numerical method for multiphase flow simulation. While having many favorable features such as incorporation of physics on the more fundamental level and efficient algorithm for fast computation, the current multiphase LBM still faces challenges in issues such as numerical instability and narrow parameter window, which severely restrict its application in a broad range of real world engineering problems.This dissertation presents the development of a novel multiphase LBM which significantly expands the application of the method in various flow problems. Specifically, three techniques are developed to achieve enhanced performance in three aspects: First, new interaction potential functions are developed for multi-component LBM model to improve numerical stability at high density ratios between the liquid and gas phase. Second, an adaptive mesh refinement (AMR) scheme is developed to provide sufficient resolution of the gas-liquid interface. Third, the multi-relaxation time (MRT) scheme is incorporated into the interaction potential model to enhance the numerical stability at low viscosities. The above new techniques are presented in detail, and simulations are performed in both 2D and 3D to evaluate their performance. It is demonstrated that the new interaction potential model is able to raise the stable density ratio from below 50 to over 1000. The AMR can provide accurate predictions of the interface, while reduce the computation cost by about 50% in real computations. In addition, with the MRT algorithm the maximum Reynolds number in bubble simulations can be increased from 100 to about 1000. The performance of the newly developed LBM technique is further illustrated in different applications. In the study of the buoyant rise of a gas bubble in a viscous liquid, simulations are carried out to investigate the shape and rise velocity of the bubble. Particularly, both bubbles with large deformation and bubbles with high Reynolds number are studied. Good agreement is found between the model predictions and experimental results in the literature. Then the collision between a liquid droplet and a porous surface is investigated. Using the adaptive mesh approach, the flows on both the droplet scale and the pore scale are direct resolved simultaneously. The deformation of the droplet on the porous surfaces is compared to that on impermeable surfaces. Finally, the LBM simulation is performed for bubble formation in microchannels. The bubble shape and formation mechanism are discussed in different regimes and compared with experimental results. In summary, a systematic investigation is conducted to improve the stability and accuracy of the LBM for multiphase simulations. A novel LBM model is developed and its performance is studied in various test problems. The application of the new model in the simulation of bubble rise, droplet collision, and microchannel bubble formation further illustrates the enhanced capability of the current LBM model.

Chapter 1. Review of concept and methodology development for asymmetric allylation of carbonyls and imines. Chapter 2. Description of the catalytic asymmetric addition of allyltrichlorosilane to aldehydes catalyzed by a proline-based N-oxide catalyst. Chapter 3. Introduction of the first catalytic asymmetric silylation of alcohols for desymmetrization of meso-diols. Chapter 4. Presentation of asymmetric silylation for synthesis of chiral syn-1,2-diols by kinetic resolution or divergent reaction on a racemic mixture.