Development of a Femtosecond Time-Resolved Raman Spectrometer for Hemoglobin Studies.

A femtosecond time-resolved Raman spectrometer is developed to study the ultrafast dynamics of hemoprotein. The laser system consists of a dye laser synchronously pumped by the SHG of compressed ML Nd:YAG laser pulse, and a Ti:sapphire regenerative amplifier using chirped-pulse-amplification technique. The laser system provides 350 fs pulses output with 0.4 mJ/pulse energy at the repetition rate of 1 kHz. The tunability covers the whole Ti:sapphire lasing range with the use of different laser dye. Femtosecond time-resolved resonance Raman experiment shows that the ligand photodissociation quantum yield depends on the nature of ligand. With three ligands studied, CO has about 100% quantum yield while O\sb2 has about 40% and NO has about 20%. No significant amount of geminate recombination observed in less than 10 ps for CO and O\sb2. However, most of the photodissociated NO ligand geminate recombines within 30 ps. The electronic relaxation of photoexcited hemoprotein occurs in about 300 fs. While the ligand dissociated hemes are relatively vibrationally cool, the ligand bound hemes subsequent to electronic relaxation are vibrationally hot. The energy is deposited in high vibrational frequency modes with a 2 ps IVR process. The EVR process occurs in about 4-5 ps. These results are in agreement with other ultrafast hemoprotein experimental observations

Fine granular deposition of clonal immunoreactivity on podocyte cell bodies: a primary podocytopathy marker and potential clue to disease mechanism

Minimal change disease (MCD) and primary (idiopathic) focal segmental glomerulosclerosis (1FSGS), referred to collectively as “primary podocytopathies”, are major causes of nephrotic syndrome in children and adults, and are thought to be due to direct podocyte damage visible only at the electron microscopic level. Lupus podocytopathy (LP) is a newly recognized entity that involves severe podocyte injury in the setting of systemic lupus erythematosus, in the complete absence of peripheral capillary wall immune deposits. All of these pathologic diagnoses hinge on the ultrastructural finding of severe podocyte injury and foot process effacement. In addition to these ultrastructural changes, we have observed the presence of fine granular anti-IgG antibody immunoreactivity on podocyte cell bodies in kidney biopsies of patients with MCD, LP, and some patients with the tip lesion variant and NOS variants of 1FSGS. To validate this finding, we compared antibody staining from primary podocytopathy biopsies with those in biopsies from patients with other disease states, including lesions associated with severe podocyte injury in the absence of immune deposits: secondary (adaptive) focal segmental glomerulosclerosis, thin basement membrane disease, diabetic nephropathy, and renal amyloidosis. We found that a fine granular pattern of anti-IgG immunoreactivity on podocyte cell bodies is a specific morphologic feature of the primary podocytopathies, including virtually all cases of MCD that we encountered, some instances of tip lesion variant and NOS variant of 1FSGS, and one cases of LP. The antigen targeted by the anti-IgG immunostaining in these biopsies exhibited one of several oligoclonal IgG heavy chain subtype plus light chain profiles. Ultra-high resolution microscopy revealed fine linear anti-IgG staining along filtration slit diaphragms, suggesting that IgG deposition may potentially be targeting a filtration slit-associated antigen such as podocin. Our findings suggest the possibility of a direct antibody-mediated mechanism of podocyte injury in the primary podocytopathies, one that potentially targets podocyte-specific protein structures, and which may provide a specific and more rapid diagnostic marker for this group of diseases. The findings also suggest an etiologic relationship between MCD and some instances of 1FSGS

A Density Functional Theory Study of the Structure and Chemistry of Zeolite Linde Type A (LTA)

Zeolites have been widely applied in several industries for filtration, size-selective catalysis, and ion exchange. Zeolite LTA has three different sized pore windows and is the focus of this work. Via density functional theory, computational simulations were performed to model the effect of different cation substitutions. One of the objectives of this research was to determine the change in structure and chemistry when substituting the pure Si-O composition with cations in various Si/Al ratios. Another objective of this research was to determine the most stable positioning for various cations. This project also investigated the adsorption of alkane and alcohol after entering the pore. The results of these simulations will shed some light on LTA zeolites as catalysts and ion-exchangers

IMPROVED DESIGN OF DTW AND GMM CASCADED ARABIC SPEAKER

In this paper, we discuss about the design, implementation and assessment of a two-stage Arabic speaker recognition system, which aims to recognize a target Arabic speaker among several people. The first stage uses improved DTW (Dynamic Time Warping) algorithm and the second stage uses SA-KM-based GMM (Gaussian Mixture Model). MFCC (Mel Frequency Cepstral Coefficients) and its differences form, as acoustic feature, are extracted from the sample speeches. DTW provides three most possible speakers and then the recognition results are conveyed to GMM training processes. A specified similarity assessment algorithm, KL distance, is applied to find the best match with the target speaker. Experimental results show that text-independent recognition rate of the cascaded system reaches 90 percent

Computational modelling of solvent effects

This thesis is concerned with developing theoretical benchmarks and computational procedures that would facilitate robust descriptions of solvent effects on molecular properties and chemical reactions. This advancement will enable chemists to design more effective chemical reagents, drug molecules and materials, thereby reducing the need for extensive experimental trial-and-error. Towards this end, this thesis has developed theoretical benchmarks to evaluate the performance of lower-cost and approximate methods in predicting solute-solvent interaction energies. This includes the generation of high-level calculations of solute-solvent interactions and proton transfer reaction energies in very large water clusters (up to 160 water molecules) at a variety of solute-solvent configurations. This differs from previous studies, which mostly focused on small solvated clusters (1-6 solvent molecules) at equilibrium geometries. These theoretical benchmarks were then used to assess the performance of a range of contemporary density functional theory methods and hybrid quantum mechanics/molecular mechanics (QM/MM) approximations of these methods. A surprising finding was that significantly larger than expected QM region size (solute plus 40 or more water molecules) was needed before the QM/MM models converged to within 5.7 kJ mol-1 of the direct QM result. To address this limitation, an important contribution of this thesis is the development of efficient strategies based on charge-shift analysis and electrostatically embedded fragment methods to accelerate the convergence of the QM/MM models with respect to QM region size. Of particular note, the QM region selection based on atomic charges significantly reduced the errors in QM/MM models even when a low-level embedding potential was used. Finally, these findings culminated in developing a dual-Hamiltonian approach that may be used to systematically improve the accuracy of force field explicit solvent simulations of barriers of organic reactions. It is envisaged that these developments will directly contribute to the development of a systematic framework for improving computational simulations of solution-phase processes

Remotely Operated Aerial Vehicles and Their Applications

This project examines relevant designs and applications of unmanned aerial vehicles (UAVs). We propose UAV design solutions, which can be refined and incorporated into emergency medical services. Mathematical and engineering concepts are used to select the design solutions. We believe that the proposed design solutions will enhance the quality of care in emergency medical services