Aside from energy, light carries linear and angular momenta that can be transferred to matter. The interaction between light and matter is governed by conservation laws that can manifest themselves as mechanical effects acting on both matter and light waves. This interaction permits remote, precise, and noninvasive manipulation and sensing at microscopic levels. In this dissertation, we demonstrated for the first time a complete set of opto-mechanical effects that are based on nonconservative forces and act at the interface between dielectric media. Without structuring the light field, forward action is provided by the conventional radiation pressure while a backward movement can be achieved through the natural enhancement of linear momentum. If the symmetry of scattered field is broken, a side motion can also be induced due to the transformation between spin and orbital angular momenta. In experiments, these opto-mechanical effects can be significantly amplified by the long-range hydrodynamic interactions that provide an efficient recycling of energy. These unusual opto-mechanical effects open new possibilities for efficient manipulation of colloidal microparticles without having to rely on intricate structuring or shaping of light beams. Optically-controlled transport of matter is sought after in diverse applications in biology, colloidal physics, chemistry, condensed matter and others. Another consequence of light-matter interaction is the modification of the optical field itself, which can manifest, for instance, as detectable shifts of the centroids of optical beams during reflection and refraction. The spin-Hall effect of light (SHEL) is one type of such beam shifts that is due to the spin-orbit transformation governed by the conservation of angular momentum. We have shown that this effect can be amplified by the structural anisotropy of random nanocomposite materials.

<p> In an investigation on the formation of halogen cations, the I4 2+, Br3+, Br2+ and Cℓ3+ cations have been identified by conductivity, cryoscopy, ultraviolet and visible spectrophotometry, Raman spectroscopy and magnetic susceptibility measurements in strong acids. Bromine trifluorosulphate has been shown to ionise in the SbF5:3SO3/HSO3F system to give the Br(SO3F)2+ ion, and Raman bands of bromine fluorosulphates, CℓSO3F and S2O6F2 have been listed. No evidence has been found for the Cℓ2+ or CℓF+ ions in solution, and the assignment of observed ESR spectra to these cations is criticised.</p> <p> Raman spectra of the adducts AsF5 2CℓF and BF3 2CℓF have shown that they contain the CℓCℓF+ cation and not the CℓFCℓ+ cation. The bending frequency of the CℓF2+ cation has been reassigned, and force constants have been calculated for the CℓF2+ and Cℓ3+ cations.</p> <p> Resonance Raman spectra of the I2+ and Br2+ cations have been observed, and, as few examples of this effect are known, the variation in fundamental and overtone intensities with exciting wavelength have been investigated.</p> / Thesis / Doctor of Philosophy (PhD)

Molecular dynamics (MD) simulations play a pivotal role in understanding the behavior of complex molecular systems, offering insights into the behavior of molecules at the atomic level, while their accuracy heavily depends on the force field parameters used. In this study, we present an investigation focusing on two distinct aspects: the validation of MD simulations for plasticizers, and the development of a quantitative structure property relationship (QSPR) model to fit data derived from these simulations. Our goal is to provide researchers with valuable insights into the choice of force fields to improve the accuracy of simulations in various scientific domains and the modeling of prediction of properties of plasticizers. In the first part, We explore various aspects of validation, including force field accuracy, equilibration protocols, and comparison of simulation results of plasticizers with experimental data. We begin by validating popular force fields: PCFF, SciPCFF and COMPASS. By examining the behavior of small molecules, we aim to ensure the reliability of force fields for these compounds with specific desired functional groups. Density, heat of vaporization and shear viscosity results are used for the validation of force fields. We compare various equilibration methods and their impact on simulation outcomes to address issues related to system stability and convergence, for enhancing the efficiency and accuracy of simulations. The second part of our research shifts focus to the prediction modeling of plasticizers, a class of chemical additives commonly used in the polymer industry to enhance the flexibility of plastic materials. We attempt to predict the solubility parameters of plasticizers by QSPR. Simple counts, Wiener Indices and Randic Branching Indices are used as descriptors in the QSPR. Our prediction model results show the dependence of plasticizers on the descriptors while the QSPR equation obtained from our current data-set with five descriptors has the R2 = 0.73. In conclusion, this comprehensive study bridges the gap between force field validation and equilibration for plasticizers. Moreover, the integration of QSPR models offers insights to a robust approach for predicting molecular behaviors. / Thesis / Master of Applied Science (MASc)

Objectives: The primary purpose of this study was to examine the difference in peak force (PF) production with and without the inclusion of lifting straps (LS) during an isometric mid-thigh pull (IMTP). An additional goal of this study was to identify potential asymmetry during the two protocols while evaluating the potential use of a dual force plate IMTP as a tool for player monitoring programs. Methods: Twenty-one NCAA division I men (n=10) and women (n=11) soccer players performed a maximal IMTP over dual force plates with and without the assistance of LS. The PF total between the two plates for both conditions was used to examine the effect of LS. Asymmetry was assessed by the PF of the separate force plates by calculation of a symmetry index (SI). Results: The PF achieved with the assistance of LS was significantly greater for males (strapped: 2102.3±506.2N, unstrapped: 1468.6±286.0N; p 1105.0±294.7N, unstrapped: 940.6±155.7N; pConclusion: The inclusion of LS on the IMTP allowed for a significantly greater PF production for male and female soccer athletes. However, the increase in PF with the inclusion of LS was greater in the males who saw a large effect size (d=1.959, pp=0.024). Both male and female soccer players possessed some level of asymmetry that did increase with the inclusion of LS, but no significant difference was found between conditions.

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Thesis (S.M. in Architecture Studies)--Massachusetts Institute of Technology, Dept. of Architecture, 2013. / 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 (p. 118-124). / Federal buildings are required to reduce 30% of their energy use intensities (energy use per square foot) by 2015 and 37.5% by 2020. Additionally, 15% of federal buildings are required to achieve an Energy Star Rating of 75 or above by 2015. Despite rigorous efforts, current Air Force healthcare building performance reveals only a 15% decrease has been achieved from the 2009 baseline levels and only 12% of the building inventory holds the Energy Star Rating. Projections similarly reveal full compliance by 2020 may not be achievable, therefore, the need for a comprehensive and more robust effort is proposed. This thesis seeks to develop a road map for the Air Force's 68 existing healthcare buildings towards compliance by 2015. A methodology has been developed that leverages the Air Force's state-of-the-art energy efficiency strategy, the building energy performance analysis for 68 healthcare facilities including ten in-depth case studies, and multi-agency interviews to produce the road map. Strategic energy management plans, building system retrofits, whole building retro commissioning, occupant behavior and medical equipment plug loads and standby loads have been assessed. Investment costs, energy savings, and return on investments present timeline objectives intended to deliver a comprehensive strategy towards energy savings in Air Force healthcare facilities by 2015. Findings indicate that an energy master plan that incorporates a systematic building diagnostics approach targeting HVAC equipment and system operations as the most effective strategy. The results reveal that HVAC retrofits and implementation of no cost measures such as temperature setpoints and setbacks collectively reduce building energy use by 85% and energy use intensities by 50% by 2015. Projections include a total budget request of $43.5 million, annual cost savings of $4.1 with a 9.4% return on investment. / by Jose I. Ramos. / S.M.in Architecture Studies

The conventional atomic force microscope (AFM) is equipped with a single optical detection system. Probe-sample separation is determined in an independent deflection with respect to AFM z-translation experiment. This method of determining probe-surface separation is relative, susceptible to drift and does not provide real time separation information. The evanescent wave atomic force microscope (EW-AFM) utilizes a second, independent detection system to determine absolute probe-surface separation in real time. The EW-AFM can simultaneously acquire real-time force and probe-sample separation information using the optical lever and evanescent scattering detection systems, respectively. The EW-AFM may be configured with feedback on the optical-lever system for constant force applications or with feedback on evanescent wave scattering intensity for constant height applications. Scattering of the evanescent wave exponential decay profile is used to determine probe-surface separation. Sub-micron sized dielectric and metallic probes show exponential scattering profiles, micron sized polystyrene and borosilicate microspheres show non-exponential profiles when they are affixed beneath the cantilever tip. By affixing the microspheres to the end of the AFM cantilever exponential and non-exponential profiles were observed. The EW-AFM can be used to conduct force-distance and imaging experiments. The EW-AFM was used to measure the thickness of surfactant bilayers formed at the silica-solution interface using silicon nitride AFM tips. The presence of a refractive index difference between the surfactant bilayer and the solution does not influence the accuracy of the surfactant bilayer thickness measurement. The EW-AFM was used to scan a 2 x 2 micron area in constant height mode. The probe was brought to within 6 nanometers of a planar dielectric surface using the evanescent wave intensity as a height reference with accuracy of ± 1 nm. This capability may be utilized to observe charge heterogeneity at the solid-liquid interface with nanometer lateral resolution or to map chemical functional group heterogeneity based on perturbations to the electrical double layer. The EW-AFM evanescent scattering system has an absolute separation resolution of 0.3 nm compared to 1.0 nm relative separation resolution for the optical lever system. In constant scattering (constant height) mode the real time separation precision is about 2 nm. / Ph. D.