Educação matemática pela arte
Gusmão, Lucimar Donizete
2013-08-28
Search results
66,926 records were found.
Currently, size is used as the predetermining factor to judge whether a saccular aneurysm is likely to rupture. Recent studies of the nonlinear mechanics of saccular aneurysms suggest that it is unlikely that they enlarge or rupture via material (limit point) or dynamic (resonance) instabilities. Rather, there is a growing body of evidence from both vascular biology and finite element analyses that implicate mechanosensitive growth and remodeling processes. There is, therefore, an even greater need to quantify regional multiaxial wall stresses, which because of the membrane-like behavior of aneurysms implicates the need for better data on regional surface curvatures. By using a convenient function, such as a Legendre polynomial, a quick, accurate approximation can be made for the size and shape of a saccular aneurysm that allows for st...
The primary objective was to study the kinetics of folding of RNase Sa. Wild-type
RNase Sa does not contain tryptophan. A tryptophan was substituted at residue
81 (WT*) to allow fluorescence spectroscopy to be used to monitor folding. This
tryptophan mutation did not change the stability. An analysis of the folding
kinetics of RNase Sa showed two folding phases, indicating the presence of an
intermediate and consistent with the following mechanism: D ↔ I ↔ N. Both
refolding limbs of the chevron plot (abcissa = final conc. of denaturant and
ordinate = kinetic rate) had non-zero slopes suggesting that proline
isomerization was not rate-limiting.
The conformational stability of a charge-reversed variant, WT*(D17R), of
a surface exposed residue on RNase Sa has been studied by equilibrium
techniques. This mutant with a single amino acid cha...
Dynamic models of a reactive distillation column have been developed and implemented in this work. A model describing the steady state behavior of the system has been built in a first step. The results from this steady state model have been compared to data provided from an industrial collaborator and the reconciled model formed the basis for the development of a dynamic model. Four controlled and four manipulated variables have been determined in a subsequent step and step tests for the manipulated variables were simulated. The data generated by the step responses was used for fitting transfer functions between the manipulated and the controlled variables. RGA analysis was performed to find the optimal pairing for controller design. Feedback controllers of PID type were designed between the paired variables found from RGA and the cont...
A numerical method for the simulation of compressible turbulent flows is presented. This method includes a novel hybrid grid generation for airfoil cascades and an unstructured mesh flow solver. The mesh tool incorporates a mapping technique and a grid smoothing method. The mapping technique is used to build an initial volume mesh and the grid smoothing method is used to improve the quality of the initial mesh. The grid smoothing is based on the optimization of mesh-quality parameters. The further improvement of the smoothed mesh is achieved by an edge-swapping and node-insertion technique. The unstructured flow solver is developed for a hybrid grid. This flow solver uses a rotational frame of reference. The convective and viscous fluxes are numerically solved by an upwind scheme and an averaged nodal grad...
Novel electrophoresis devices for protein and DNA separation and identification
have been presented and studied. The new device utilizes a contact resistance change
detection method to identify protein and DNA in situ. The devices were prepared with a
microelectronic micromechanical system (MEMS) fabrication method. Three model
proteins and six DNA fragments were separated by polyacrylamide gel microchannel
electrophoresis and surface electrophoresis. The detection of the proteins or DNA
fragments was accomplished using the contact resistance increase of the detection
electrode due to adsorption of the separated biomolecules. Key factors for the success of
these devices were the optimization of fabrication process and the enhancement of
detection efficiency of the devices. Parameters, such as microchannel configuration, size
of electro...
Natural products continue to influence society at large as many drugs are of
natural product origin. Consequently, the development and study of new chemical
reactions that lead to the efficient preparation of natural products is a central goal in
organic chemistry today. To this end, we have investigated the reactivity and
stereoselectivity of cyclic 2-(N-acylamino)-1,3-dienes toward a total synthesis of
stenine. Chapter I describes the isolation and characterization of stenine, in addition to
comparing five published total syntheses of stenine.
Chapter II discusses synthetic and theoretical investigations of cyclic 2-(Nacylamino)-
1,3-dienes. We have shown that vinylazepenes react with Nphenylmaleimide
to afford exo cycloadducts exclusively. Previous studies of
vinylpiperidenes revealed a preference for endo selectivity. We confirmed ...
The present research presents procedures for exploitation of level sensitive latches in wire pipelining. The user gives a Steiner tree, having a signal source and set of destination or sinks, and the location in rectangular plane, capacitive load and required arrival time at each of the destinations. The user also defines a library of non-clocked (buffer) elements and clocked elements (flip-flop and latch), also known as synchronous elements. The first procedure performs concurrent repeater and synchronous element insertion in a bottom-up manner to find the minimum latency that may be achieved between the source and the destinations. The second procedure takes additional input (required latency) for each destination, derived from previous procedure, and finds the repeater and synchronous element assignments for all internal nodes of th...
The degradation of phosphate triesters is efficiently catalyzed by organophosphate hydrolases (OPH). While a number of recent studies have focused on optimizing the rate of hydrolysis observed with the native enzyme, no dinuclear complexes that mimic the function of OPH have been reported or investigated. Our present research focuses on the synthesis of dinuclear metal complexes and on the study of their catalytic abilities. An important aspect of this research concerns the investigation of the coordination chemistry of dinuclear ligands designed to hold two metal cations in well defined positions. The ability of the different complexes to catalyze the degradation of thiophosphate triester is presented. Out of several complexes studied, ortho-metallated Pd (II) complexes have been found to display the highest catalytic activity for the...
Most new fields in chemistry usually began as a curiosity by the researchers, followed by an intrinsic interest in basic biological, physical and chemical properties of reactions, interactions, structural features, and response to external stimuli by chemical elements and/or chemical compounds. If the curiosity has appealing bio-physico-chemical properties this trend is followed by studies on the possible applications of such new fields. As a result, is it expected that these curiosities develop or give insights into new technologies. The development of the field of dendrimer chemistry is no different. In fact, dendrimer chemistry illustrates this trend fittingly.
The research in this dissertation follows a similar trend. First, the synthesis of a melamine-based dendrimer is achieved. The synthesis illustrates the concept of using t...
Past research on eighteenth-century ships has primarily taken one of two avenues, either focusing on naval warship construction or examining the merchant shipping industry as a whole in terms of trends and economics. While these areas are important to pursue, comparatively little is known about actual construction techniques used on the ordinary merchant vessels of the period. Most modern sources emphasize hull design and lines drawings; contemporary sources take a similar direction, explaining the theory of ship design but often leaving out how to put the ship together. In recent years, however, new information has come to light through archaeological excavations regarding Anglo-American merchant ship construction. In this study, several of these shipwrecks were examined in light of economic factors and the literary evidence from the ...
