353 research outputs found

    Method Development Toward the Analysis of the Functionalization of Proteins

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    Calmodulin is a ubiquitous small intracellular protein that functions as a receptor for regulatory calcium signals and thus regulates a multitude of physiological processes in organisms as diverse as yeast, fruit flies, and mammals. Since its structure and function have been extensively studied, our goal is to create a calmodulin biomaterial, with the ultimate goal of in situ drug delivery or as a scaffold for stem cell growth and differentiation. We plan to create this biomaterial by using Click Chemistry, the rapid creation of new heteroatom bonds through a copper-catalyzed azide-alkyne cycloaddition. The bonds are created by treating calmodulin as an organic reagent and derivatizing the hydroxyl group of the amino acid tyrosine for an organic fluorophore. However, since tyrosines appear at residues 99 and 138, functionalization could be occurring at multiple sites. A reliable protocol has to be developed to determine the exact position of functionalization on calmodulin. We will focus on determining if and where functionalization occurs by employing an enzyme to cleave between the two tyrosines. Thrombin, a protease, offers a convenient analytical solution by cleaving the protein between two tyrosines, as it hydrolyzes the protein backbone at the C-terminal side of arginine (residue 106), which is located in between the tyrosines (residues 99 and 138). In finding a mechanism through which we are able to successfully separate the tyrosines on calmodulin, we will determine which, if either, has been derivatized by then performing gel electrophoresis, mass spectrometry, or chromatography

    Synthesis of Silane and Silicon in a Non-equilibrium Plasma Jet

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    The original objective of this program was to determine the feasibility of high volume, low-cost production of high purity silane or solar cell grade silicon using a non equilibrium plasma jet. The emphasis was changed near the end of the program to determine the feasibility of preparing photovoltaic amorphous silicon films directly using this method. The non equilibrium plasma jet should be further evaluated as a technique for producing high efficiency photovoltaic amorphous silicon films

    Properties of generic and almost every mappings in various nonlogically compact Polish abelian groups.

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    In a nonlocally compact Polish abelian group G, we will consider two notions of smallness of subsets of G. Those subsets of G which are topologically small are said to be meager, and those which are measure-theoretically small are Haar null. We will say that a property P holds for a generic g € G if the property holds on the complement of a meager subset of G, and P holds for almost every g € G if the property holds on the complement of a Haar null set. Thus the phrase a randomly chosen element of G is likely to have property P may be understood to have two different meanings in this paper. The spaces Zz and C(Rn), n = 1, the continuous self-maps of Z and Rn, respectively, are both nonlocally compact Polish abelian groups. In this paper we will study properties of generic and almost every mappings in Zz and Rn, and properties of generic mappings in C(Rn). In the space Zz, we show that the behavior of a generic (phi) € C® is quite different than the behavior of almost every (phi)€ Zz. We will show that in the space C®, the behavior of a generic f € C® is analogous to the behavior of a generic (phi) € Zz in several ways, but the analogies between the spaces Zz and C® seem to cease when the properties of almost every f € C® are considered. In fact, many of the properties of functions in C® that we consider in this paper are shown to be H-ambivalent; that is, the properties hold on a set which is neither Haar null nor the complement of a Haar null set. We will present preliminary results concerning the behavior of a generic f € C(Rn). We will show that several of the properties which hold for a generic f € C® also hold in the more general setting of a generic f € C(Rn), although the proofs techniques differ. Finally, we will close with a discussion of future directions that this work may take

    One bug, two drugs : A mathematical model of resistance dynamics in the ICU.

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    Antibiotic resistance is a problem causing growing concern in the medical community, leading some to speculate that a return to the preantibiotic era is imminent. The problem of antibiotic resistance is particularly significant in the intensive care unit (ICU), due to the weakened immune responses of the patients and quantity of antibiotics administered. One theory proposes that the policy of cycling, or rotating, the antibiotics used in the ICU may minimize the development of resistance. Few clinical trials investigating the effects of cycling have been conducted, and many questions concerning the impact of cycling policies are unanswered at this point. In this thesis, we develop and analyze a mathematical model designed to examine resistance dynamics in the ICU in response to a cycling policy. The uncertainty analysis performed on the model evaluates the variability of the model outcome due to the uncertainty in estimating input values. The chosen method of analysis is Latin Hypercube Sampling (LHS). This uncertainty analysis is extended with the Latin Hypercube Sampling/Partial Rank Correlation (LHS/PRC) sensitivity analysis technique, which identifies the input variables that have the greatest effect on the model outcome. The analysis results show that the prediction imprecision of the model is quite high, leading us to conclude that the model\u27s potential as an investigative tool cannot be fully realized until input values can be estimated with greater certainty

    Characterization of a spark ignition system for flameholding cavities

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    This paper presents an experimental investigation of a capacitive-discharge spark ignition system designed to promote ignition in CH- and CH-fuelled supersonic combustors. The purpose of this study is the characterization of the ignition system and the plasma generated in the discharge. Schlieren and luminescence imaging are used to visualize the temporal evolution of the spark plasma. Transient voltages and currents across the primary-side of the ignition coil and input-side of the ignition unit are recorded using a high-speed data acquisition system. Three different ignition coils are tested with two different spark plug gaps in an attempt to increase the performance of the ignition system which is evaluated through spatially and temporally integrated luminescence recordings as well as temporally integrated photo diode signals. The data suggests that an increase in performance of a factor of 4-5 over the baseline setup can be achieved. A capacitive ignition lead is used to assess whether or not any capacitance on the coil secondary side can increase the performance of the ignition system. The experiments have also shown that the ignition system parameters can be set to cause sufficient heating of the electrodes to support ignition from a combined glow-spark plug setup

    Retrofit Railings for Narrow Through Truss and Other Obsolete Bridge Structures

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    DOT-FH-11-9418Through truss structures are unique in that the superstructure of the bridge is exposed to impacts from errant vehicles. Effective bridge railings must not only exclude these vehicles from contacting the critical truss members by limiting system deflection, but must also prevent heavy vehicles from rolling over the barrier and contacting a truss member. Complete collapse of truss structures has resulted from automobile impacts as well as heavy vehicle impacts. Two bridge railing retrofit systems were systematically designed and developed in this project. The high performance system is designed to contain and limit vehicle roll of 20,000-lb (9000-kg) buses impacting at 55 mph (90 kmph) and a 15-deg angle. The low service retrofit system contains and redirects a 4500-lb (2000-kg) car impacting at 60 mph (95 kmph) and a 15-deg angle without endangering the truss members behind the retrofit system. Crash tests with vehicles ranging from the bus to an 1800-lb (800-kg) minicompact vehicle were used in the development and evaluation. Design drawings of the bridge rails, bridge attachment detail and approach rail are included in the report

    Guardrail-Bridge Rail Transition Designs, Volume I: Research Report

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    DTFH61-83-C-00028This project was concerned with the transition designs used between w-beam and the guardrail, and rigid bridge rail parapets or wingwalls. State designs submitted to the federal highway administration (FHWA) were rated and designs selected for crash test evaluation. New designs were also formulated and subjected to crash test evaluation. Most of the crash tests were conducted with 4500 lb (2000 kg) cars at 60 mph (95 km/h) and a 25 degree angle. Design drawings are presented along with recommendations for use of these transition designs. Guidelines for transition features are given and design procedures for independent end blocks are given

    Study of the phase-varying mechanisms of ion current signals for combustion phasing in a gasoline HCCI engine

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    This work was supported by National Basic Research Priorities Program (973) of China under the Grant reference of 2007CB 210005.The phase-varying mechanism of the ion current observed in a Homogeneous Charge Compression Ignition (HCCI) engine is investigated to achieve ion current-based combustion phasing. By integrating the gasoline flame ionization mechanism with the HCCI combustion model, the mechanisms affecting the ion formation and recombination processes are analyzed, and the relationship between the phases of ion current and combustion event is studied. Modeling results indicate that the formation rate of H 3 O + ions is mainly affected by the combustion boundary conditions. However, the ion recombination rate of H 3 O + ions is mainly dependent on the concentration of these ions. In the presence of the above mechanisms, the phase-varying tendency of the ion current is found to be similar to the variations in the combustion phase, but the offset between these phases will vary when the combustion boundary condition changes. As the equivalence ratio becomes low, the rate of H 3 O + formation is decreased and the ion recombination rate decreases even more, due to the reduced ion concentration. Therefore, the inflection point of the ion current curve, dI max , is retarded even further compared to the combustion phase CA50. In addition, a larger phase offset between dI max and CA50 is observed when the intake temperature is lower. All of the above modeling predictions agree well with the experimental results

    Pollen signals of ground flora in managed woodlands

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    This paper explores the vegetation signals contained in the non-arboreal pollen and spore (NAPS) components of pollen assemblages from Tauber traps placed in woodlands subject to rotational cutting (coppicing) in lowland England. Sets of three Tauber traps were placed in compartments of different ages at multiple locations within each woodland for 1 year, and pollen assemblages recorded along with a vegetation survey using a modified pin-frame method in an area of 10 m radius around each trap array. Cluster analysis suggests that, as expected, the ground layer vegetation broadly reflects the different environmental conditions in the three woods, with the main subdivisions within woods apparently driven by changes in ground cover between the early and late stages of the coppice cycle. Non-arboreal pollen and spores (NAPS) assemblages group according to woodland of origin, with subdivisions which relate to pollen abundance but lack a simple relationship with years since cutting. Indices of Association between NAPS records and plant presence in the area around each array were calculated using presence–absence data for multiple distances of vegetation survey. All values tend towards an asymptote, which is interpreted as implying an effective source area for the single taxon presence–absence indicator values of ground flora taxa in coppiced woodlands on the order of a 10 m radius. Only four taxa, Poaceae, Ranunculus acris-type, Cyperaceae, and Scilla-type, have an Index of Association (A) greater than 0.5, implying that the presence of pollen can be interpreted in terms of the local presence of the relevant plant taxon with some confidence. Estimates of Pollen Productivity relative to Poaceae are presented for five taxa: Apiaceae, Asteraceae (Cardueae), Cyperaceae, Mercurialis perennis, and Scilla-type. Years since cutting does affect the ground vegetation and NAPS assemblage trapped in these woods, but that the effect is more clearly seen at an assemblage level in the vegetation than in the pollen assemblages. The interpretative significance of NAPS taxa does not seem to be in providing information about the local conditions around the sampling point, but in reflecting the ground flora of the wider woodland

    Development of a Diesel Surrogate Fuel Library

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    [EN] Diesel fuel is composed of a complex mixture of hundreds of hydrocarbons that vary globally depending on crude oil sources, refining processes, legislative requirements and other factors. In order to simplify the study of this fuel, researchers create surrogate fuels to mimic the physical and chemical properties of Diesel fuels. This work employed the commercial software Reaction Workbench - Surrogate Blend Optimizer (SBO) to develop a Surrogate Fuel Library containing 18 fuels. Within the fuel library, the cetane number ranges from 35 to 60 (in increments of 5) at threshold soot index (TSI) levels representative of low, baseline and high sooting tendency fuels (TSI = 17, 31 and 48, respectively). The Surrogate Fuel Library provides the component blend ratios and predicted properties for cetane number, threshold soot index, lower heating value, density, kinematic viscosity, molar hydrogen-to-carbon ratio and distillation curve temperatures from T-10 to T-90. A market petroleum Diesel fuel with a cetane number of 50 and a threshold soot index of 31 was selected as the Baseline Diesel Fuel. The combustion, physical and chemical properties of the Baseline Diesel Fuel were precisely matched by the Baseline Surrogate Fuel. To validate the SBO predicted fuel properties, a set of five surrogate fuels, deviating in cetane number and threshold soot index, were blended and examined with ASTM tests. Good agreement was obtained between the SBO predicted and ASTM measured fuel properties. To further validate the Surrogate Fuel Library, key properties that were effected by altering the component blend ratios to control cetane number and TSI were compared to a set of five market Diesel fuels with good results. These properties included density, viscosity, energy density and the T-10 and T-90 distillation temperatures. The Surrogate Fuel Library provided by this work supplies Diesel engine researchers and designers the ability to analytically and experimentally vary fuel cetane number and threshold soot index with fully-representative surrogate fuels. This new capability to independently vary cetane number and threshold soot index provides a means to further enhance the understanding of Diesel combustion and design future combustion systems that improve efficiency and emissions.Szymkowicz, P.; Benajes, J. (2018). Development of a Diesel Surrogate Fuel Library. Fuel. 222:21-34. https://doi.org/10.1016/j.fuel.2018.01.112S213422
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