Experimental studies of the formation/deposition of sodium sulfate in/from combustion gases

Interference in a reflected beam of monochromatic light from a linearly polarized helium-neon laser was used to determine the dew point and deposition rate of B2O3 on a heated platinum target. Preliminary results at different BCl3 seed levels, except for one flow velocity and equivalence ratio (.813) are presented and discussed. Alkali chloride reactions with atomic oxygen were also investigated. Readily detectable Na*(g) and K*(g) - atoms were observed in emission at 589 nm, 766nm, 796nm, respectively

Experimental Studies of the Formation/Deposition of Sodium Sulfate in/from Combustion Gases

Processes related to the hot corrosion of gas turbine components were examined in two separate investigations. Monochromatic laser light was used to probe condensation onset and condensate film growth (via interference of reflected light) on electrically heated ribbons immersed in seeded, flat flame combustion product gases. Boron trichloride is used as the seed gas in these preliminary experiments conducted to obtain precise measurements of the dew point/deposition rates. Because of the importance of gaseous Na(g) as a precursor to NaSO4 formation, the kinetics and mechanisms of the heterogeneous reaction H(g) + NaCl(s) yields Na(g) + HCl(g) was studied using atomic absorption spectroscopy combined with microwave discharge-vacuum flow reactor techniques at moderate temperatures. Preliminary results indicate the H-atom attack of solid NaCl vaporization is negligible; hence the corresponding gas phase (homogeneous) reaction no role in the observed Na(g) production

Easy Integral Surfaces: A Fast, Quad-based Stream and Path Surface Algorithm

a fast, quad-based stream and path surface algorith

Computational Study of a Generic T-tail Transport

This paper presents a computational study on the static and dynamic stability characteristics of a generic transport T-tail configuration under a NASA research program to improve stall models for civil transports. The NASA Tetrahedral Unstructured Software System (TetrUSS) was used to obtain both static and periodic dynamic solutions at low speed conditions for three Reynolds number conditions up to 60 deg angle of attack. The computational results are compared to experimental data. The dominant effects of Reynolds number for the static conditions were found to occur in the stall region. The pitch and roll damping coefficients compared well to experimental results up to up to 40 deg angle of attack whereas yaw damping coefficient agreed only up to 20 deg angle of attack

Visualization of Time-Varying Data from Atomistic Simulations and Computational Fluid Dynamics

Time-varying data from simulations of dynamical systems are rich in spatio-temporal information. A key challenge is how to analyze such data for extracting useful information from the data and displaying spatially evolving features in the space-time domain of interest. We develop/implement multiple approaches toward visualization-based analysis of time-varying data obtained from two common types of dynamical simulations: molecular dynamics (MD) and computational fluid dynamics (CFD). We also make application case studies. Parallel first-principles molecular dynamics simulations produce massive amounts of time-varying three-dimensional scattered data representing atomic (molecular) configurations for material system being simulated. Rendering the atomic position-time series along with the extracted additional information helps us understand the microscopic processes in complex material system at atomic length and time scales. Radial distribution functions, coordination environments, and clusters are computed and rendered for visualizing structural behavior of the simulated material systems. Atom (particle) trajectories and displacement data are extracted and rendered for visualizing dynamical behavior of the system. While improving our atomistic visualization system to make it versatile, stable and scalable, we focus mainly on atomic trajectories. Trajectory rendering can represent complete simulation information in a single display; however, trajectories get crowded and the associated clutter/occlusion problem becomes serious for even moderate data size. We present and assess various approaches for clutter reduction including constrained rendering, basic and adaptive position merging, and information encoding. Data model with HDF5 and partial I/O, and GLSL shading are adopted to enhance the rendering speed and quality of the trajectories. For applications, a detailed visualization-based analysis is carried out for simulated silicate melts such as model basalt systems. On the other hand, CFD produces temporally and spatially resolved numerical data for fluid systems consisting of a million to tens of millions of cells (mesh points). We implement time surfaces (in particular, evolving surfaces of spheres) for visualizing the vector (flow) field to study the simulated mixing of fluids in the stirred tank

Structural and biophysical analysis of important biomedical enzymes and nano-architectures

Dopa decarboxylase (DDC) is an important enzyme in the catecholamine biosynthesis pathways. Catecholamines, e.g., dopamine, serotonin, etc. often are the major neuromodulators or neurotransmitters. Hence, DDC plays a key role in regulation of neurodegenerative diseases like Parkinson’s disease (PD). In order to achieve a medicine for PD, a successful inhibitor for DDC, that could reduce the activity of DDC in the blood while making it more effective in brain, is required. An effective design of an inhibitor requires a detailed structural study of human DDC. It was aimed to solve the DDC structure by X-ray crystallography. In order to have enough protein the DDC encoding gene has been cloned in the pET21d vector which was later termed as pET-DDC-His. However, it required numerous trials and errors until a suitable condition for soluble DDC expression was found. Addition of additives like PLP, ethanol, a complex of sorbitol and betaine in the growth medium of the bacteria did not help bring the protein in the soluble part as it formed inclusion bodies. Several soluble protein fusions with DDC, like Thioredoxin and Glutathione-S-transferase were also not quite helpful towards achieving soluble expression of DDC. Finally, a coexpression of DDC along with bacterial chaperone proteins, e.g., GroEL and GroES (after cotransforming both the DDC and Chaperone protein encoding plasmid in the same E.coli cell, used for expression) lead to solubilization of recombinant human DDC. This enzyme was then purified to homogeneity by successively passing the crude bacterial proteins through Ni-chelate-affinity chromatography and Size Exclusion Chromatography. The purified protein (>90 % purity) did not produce a good yield (4mg/ 8L culture), but this was enough to start the initial crystallization trial. Using a scale up to a 50 L culture, quite a good amount of protein was achieved. The homogeneity of DDC was further confirmed by using Multi-Angle Light Scattering and Blue Native PAGE. The dimeric enzyme preparation was then utilized for crystallization using the Hanging Drop Vapor Diffusion method. In a particular condition of the crystal screens trigonal bipyramidal crystals formed. However, these crystals did not show good diffraction when bombarded with X-ray beams. Later, this particular crystallization condition remained irreproducible. The peptide nanoparticle, designed and produced in our lab, could possibly be a very valuable tool in biomedical applications, e.g., in designing vaccines, delivering drugs, bioimaging, serodiagnosis, etc. The design of the peptide nanoparticles is based on the application of the symmetry elements of virus icosahedral capsid on a specially designed building block peptide. The designed peptide building block contains two oligomerization motifs, i.e., a trimeric coiled coil and a pentameric coiled coil joined by a linker region. Sixty such peptide units, upon self-assembly, would produce peptide nanoparticle mimicking a small icosahedral virus particle. The peptide chains in the building block provide flexibility in the design so that an additional peptide could be attached to it at the C-terminus in order to functionalize the peptide nanoparticle for various biomedical applications. First of all, the functional peptide at the C-terminus could be an epitope for the antibody of a life threatening disease like HIV. These peptide nanoparticles can then function as the potent vaccine candidate for that particular disease. In this thesis work, I have attached the two epitopes against the two broadly neutralizing classes of antibody for HIV infection, 2F5 and 4E10, to the peptide nanoparticle. Secondly, another sequence of peptide, which proved to have the capacity of seeding gold on its surface, was attached to the building block peptide unit. The nanoparticle, functionalized with such a peptide, can decorate a gold layer surrounding it. Gold coating on the peptide nanoparticle scaffold can provide a nanostructure, called ‘nanoshells’, which could be very important in the field of therapeutics because of its ability in easy detection and quick treatment of cancer cells. Lastly, I added three peptides; those are recognized in the culture filtrates of M.tuberculosis isolated from TB patients, separately, to the basic peptide construct to form three different nanoparticles. Also, I tried to make a single nanoparticle that displays all the three peptides on its surface. Such a nanoparticle could be a very useful tool in the serodiagnosis or the antibody-based rapid detection of the deadly disease- Tuberculosis. The nanoparticle formation in each of the above-mentioned cases was more or less successful. One of the constructs could successfully even produce gold shells on the peptide nanoparticle

Surface-based flow visualization

This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/computers-and-graphics/.With increasing computing power, it is possible to process more complex fluid simulations. However, a gap between increasing\ud data size and our ability to visualize them still remains. Despite the great amount of progress that has been made in the field of\ud flow visualization over the last two decades, a number of challenges remain. Whilst the visualization of 2D flow has many good\ud solutions, the visualization of 3D flow still poses many problems. Challenges such as domain coverage, speed of computation, and\ud perception remain key directions for further research. Flow visualization with a focus on surface-based techniques forms the basis\ud of this literature survey, including surface construction techniques and visualization methods applied to surfaces. We detail our\ud investigation into these algorithms with discussions of their applicability and their relative strengths and drawbacks. We review the\ud most important challenges when considering such visualizations. The result is an up-to-date overview of the current state-of-the-art\ud that highlights both solved and unsolved problems in this rapidly evolving branch of research

A review of high-solid anaerobic digestion (HSAD):From transport phenomena to process design

High-solid anaerobic digestion (HSAD) is an attractive organic waste disposal method for bioenergy recovery and climate change mitigation. The development of HSAD is facing several challenges such as low biogas and methane yields, low reaction rates, and ease of process inhibition due to low mass diffusion and mixing limitations of the process. Therefore, the recent progress in HSAD is critically reviewed with a focus on transport phenomena and process modelling. Specifically, the work discusses hydrodynamic phenomena, biokinetic mechanisms, HSAD-specific reactor simulations, state-of-the-art multi-stage reactor designs, industrial ramifications, and key parameters that enable sustained operation of HSAD processes. Further research on novel materials such as bio-additives, adsorbents, and surfactants can augment HSAD process efficiency, while ensuring the stability. Additionally, a generic simulation tool is of urgent need to enable a better coupling between biokinetic phenomena, hydrodynamics, and heat and mass transfer that would warrant HSAD process scale-up

Redefining Stewardship: Public Lands and Rural Communities in the Pacific Northwest

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