Freio eletrodinamométrico usando um inversor de frequência e um motor de indução trifásico

Considering that the Brazilian energy source is based on hydroelectric power plants, every moment that it does not rain enough, we are likely to suffer power outage. Making the rational use of energy not only is wise, but also important for financial issues. The industrial sector is of great importance to Brazilian economic context, because it is one that creates more wealth and jobs. It should be noted that it is one of the sectors that consume more electricity. One of the most used equipment in industry is the three phase induction motor, which ends up providing significant waste of energy. For that reasons, studying three phase induction motors is important. One of the ways to evaluate the parameter of the three phase induction motor is using a dynamometer mechanic or electric. This work aims at further studies (and development) of electrodynamometer brake, a type of electrical dynamometer, that is the only one with reversible use. This means, it is possible to measure both the torque and the power transmitted by the electric motors, by the direct method and the indirect. Besides it allows greater stability in the imposition of charges, due to its nature of being able to regenerate the energy imparted by the engines being tested

Análise dos ciclos operacionais para especificação de motores de indução trifásicos

This paper addresses the three-phase induction motor by a thermal analysis of its operation, under the gaze of the standards of the Brazilian Association of Technical Standards that deal with working arrangements (operating cycles) defined by appropriate tests and for each use of the motor basis of this study, emphasizing especially the fact of the first three cycles are the cycles with greater possibilities of use for scaling a three-phase induction motor for the main industrial processes, will also be made an analysis of the reasons why the three-phase induction motors have a loss of power at altitudes above 1000 m above sea level and some methods of how to define how a three phase induction motor can be used in one of the first three working arrangements

Freio eletrodinamométrico usando um inversor de frequência e um motor de indução trifásico

Considering that the Brazilian energy source is based on hydroelectric power plants, every moment that it does not rain enough, we are likely to suffer power outage. Making the rational use of energy not only is wise, but also important for financial issues. The industrial sector is of great importance to Brazilian economic context, because it is one that creates more wealth and jobs. It should be noted that it is one of the sectors that consume more electricity. One of the most used equipment in industry is the three phase induction motor, which ends up providing significant waste of energy. For that reasons, studying three phase induction motors is important. One of the ways to evaluate the parameter of the three phase induction motor is using a dynamometer mechanic or electric. This work aims at further studies (and development) of electrodynamometer brake, a type of electrical dynamometer, that is the only one with reversible use. This means, it is possible to measure both the torque and the power transmitted by the electric motors, by the direct method and the indirect. Besides it allows greater stability in the imposition of charges, due to its nature of being able to regenerate the energy imparted by the engines being tested

An electrochemical gas sensor based on paper supported room temperature ionic liquids

A sensitive and fast-responding membrane-free amperometric gas sensor is described, consisting of a small filter paper foil soaked with a room temperature ionic liquid (RTIL), upon which three electrodes are screen printed with carbon ink, using a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs as well as their easy immobilization into a porous and inexpensive supporting material such as paper. Moreover, thanks to a careful control of the preparation procedure, a very close contact between the RTIL and electrode material can be achieved so as to allow gaseous analytes to undergo charge transfer just as soon as they reach the three-phase sites where the electrode material, paper supported RTIL and gas phase meet. Thus, the adverse effect on recorded currents of slow steps such as analyte diffusion and dissolution in a solvent is avoided. To evaluate the performance of this device, it was used as a wall-jet amperometric detector for flow injection analysis of 1-butanethiol vapours, adopted as the model gaseous analyte, present in headspace samples in equilibrium with aqueous solutions at controlled concentrations. With this purpose, the RTIL soaked paper electrochemical detector (RTIL-PED) was assembled by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide as the wicking RTIL and printing the working electrode with carbon ink doped with cobalt(II) phthalocyanine, to profit from its ability to electrocatalyze thiol oxidation. The results obtained were quite satisfactory (detection limit: 0.5 mu M; dynamic range: 2-200 mu M, both referring to solution concentrations; correlation coefficient: 0.998; repeatability: +/- 7% RSD; long-term stability: 9%), thus suggesting the possible use of this device for manifold applications.

Linking origin of the electric field-assisted beta-PbF2 crystallization in lead oxyfluoroborate glasses below T (g) to simultaneous cathode/anode-compensated electrochemical reactions

Full validation of the electrochemical mechanisms so far postulated as driving force of electric field-assisted non-spontaneous crystallization development in given glasses has suffered experimental restrictions. In this work, we looked into origin of this phenomenon in lead oxyfluoroborate glasses, resulting in beta-PbF2 growth even below the corresponding glass transition temperatures, through achieving a systematic study of not only Pt,Ag/Glass/Ag,Pt- but also Pt,Ag/Glass/YSZ:PbF2/Ag,Pt-type cells, where YSZ:PbF2 represents a two-phase system (formed by Y2O3-doped ZrO2 and PbF2). It is demonstrated that crystallization induction in these glasses involves Pb2+ ions reduction at the cathode, the phenomenon being, however, confirmed only when the F- ions were simultaneously also able to reach the anode for oxidation, after assuring either a direct glass-anode contact or percolation pathways for free fluoride migration across the YSZ:PbF2 mixtures. A further support of this account is that the electrochemically induced beta-PbF2 phase crystallizes showing ramified-like microstructure morphology that arises, accordingly, from development of electroconvective diffusion processes under electric field action.

Selective Permeation and Organic Extraction of Recombinant Green Fluorescent Protein (gfpuv) from Escherichia coli

Background Transformed cells of Escherichia coli DH5-α with pGFPuv, induced by IPTG (isopropyl-β-d-thiogalactopyranoside), express the green fluorescent protein (gfpuv) during growth phases. E. coli subjected to the combination of selective permeation by freezing/thawing/sonication cycles followed by the three-phase partitioning extraction (TPP) method were compared to the direct application of TPP to the same culture of E. coli on releasing gfpuv from the over-expressing cells. Material and Methods Cultures (37°C/100 rpm/ 24 h; μ = 0.99 h-1 - 1.10 h-1) of transformed (pGFP) Escherichia coli DH5-α, expressing the green fluorescent protein (gfpuv, absorbance at 394 nm and emission at 509 nm) were sonicated in successive intervals of sonication (25 vibrations/pulse) to determine the maximum amount of gfpuv released from the cells. For selective permeation, the transformed previously frozen (-75°C) cells were subjected to three freeze/thaw (-20°C/ 0.83°C/min) cycles interlaid by sonication (3 pulses/ 6 seconds/ 25 vibrations). The intracellular permeate with gfpuv in extraction buffer (TE) solution (25 mM Tris-HCl, pH 8.0, 1 mM β-mercaptoethanol β-ME, 0.1 mM PMSF) was subjected to the three-phase partitioning (TPP) method with t-butanol and 1.6 M ammonium sulfate. Sonication efficiency was verified on the application to the cells previously treated by the TPP method. The intra-cell releases were mixed and eluted through methyl HIC column with a buffer solution (10 mM Tris-HCl, 10 mM EDTA, pH 8.0). Results The sonication maximum released amount obtained from the cells was 327.67 μg gfpuv/mL (20.73 μg gfpuv/mg total proteins – BSA), after 9 min of treatment. Through the selective permeation by three repeated freezing/thawing/sonication cycles applied to the cells, a close content of 241.19 μg gfpuv/mL (29.74 μg gfpuv/mg BSA) was obtained. The specific mass range of gfpuv released from the same cultures, by the three-phase partitioning (TPP) method, in relation to total proteins, was higher, between 107.28 μg/mg and 135.10 μg/mg. Conclusions The selective permeation of gfpuv by freezing/thawing/sonication followed by TPP separation method was equivalent to the amount of gfpuv extracted from the cells directly by TPP; although selective permeation extracts showed better elution through the HIC column.

Complex materials via colloidal crystallization

The work presented in this thesis deals with complex materials, which were obtained by self-assembly of monodisperse colloidal particles, also called colloidal crystallization. Two main fields of interest were investigated, the first dealing with the fabrication of colloidal monolayers and nanostructures, which derive there from. The second turned the focus on the phononic properties of colloidal particles, crystals, and glasses. For the fabrication of colloidal monolayers a method is introduced, which is based on the sparse distribution of dry colloidal particles on a parent substrate. In the ensuing floating step the colloidal monolayer assembles readily at the three-phase-contact line, giving a 2D hexagonally ordered film under the right conditions. The unique feature of this fabrication process is an anisotropic shrinkage, which occurs alongside with the floating step. This phenomenon is exploited for the tailored structuring of colloidal monolayers, leading to designed hetero-monolayers by inkjet printing. Furthermore, the mechanical stability of the floating monolayers allows the deposition on hydrophobic substrates, which enables the fabrication of ultraflat nanostructured surfaces. Densely packed arrays of crescent shaped nanoparticles have also been synthesized. It is possible to stack those arrays in a 3D manner allowing to mutually orientate the individual layers. In a step towards 3D mesoporous materials a methodology to synthesize hierarchically structured inverse opals is introduced. The deposition of colloidal particles in the free voids of a host inverse opal allows for the fabrication of composite inverse opals on two length scales. The phononic properties of colloidal crystals and films are characterized by Brillouin light scattering (BLS). At first the resonant modes of colloidal particles consisting of polystyrene, a copolymer of methylmethacrylate and butylacrylate, or of a silica core-PMMA shell topography are investigated, giving insight into their individual mechanical properties. The infiltration of colloidal films with an index matching liquid allows measuring the phonon dispersion relation. This leads to the assignment of band gaps to the material under investigation. Here, two band gaps could be found, one originating from the fcc order in the colloidal crystal (Bragg gap), the other stemming from the vibrational eigenmodes of the colloidal particles (hybridization gap).

Dynamic wetting of complex liquids

A simple dependency between contact angle θ and velocity or surface tension has been predicted for the wetting and dewetting behavior of simple liquids. According to the hydrodynamic theory, this dependency was described by Cox and Voinov as θ ∼ Ca^(1/3) (Ca: Capillary number). For more complex liquids like surfactant solutions, this prediction is not directly given.rnHere I present a rotating drum setup for studying wetting/dewetting processes of surfactant solutions on the basis of velocity-dependent contact angle measurements. With this new setup I showed that surfactant solutions do not follow the predicted Cox-Voinov relation, but showed a stronger contact angle dependency on surface tension. All surfactants independent of their charge showed this difference from the prediction so that electrostatic interactions as a reason could be excluded. Instead, I propose the formation of a surface tension gradient close to the three-phase contact line as the main reason for the strong contact angle decrease with increasing surfactant concentration. Surface tension gradients are not only formed locally close to the three-phase contact line, but also globally along the air-liquid interface due to the continuous creation/destruction of the interface by the drum moving out of/into the liquid. By systematically hindering the equilibration routes of the global gradient along the interface and/or through the bulk, I was able to show that the setup geometry is also important for the wetting/dewetting of surfactant solutions. Further, surface properties like roughness or chemical homogeneity of the wetted/dewetted substrate influence the wetting/dewetting behavior of the liquid, i. e. the three-phase contact line is differently pinned on rough/smooth or homogeneous/inhomogeneous surfaces. Altogether I showed that the wetting/dewetting of surfactant solutions did not depend on the surfactant type (anionic, cationic, or non-ionic) but on the surfactant concentration and strength, the setup geometry, and the surface properties.rnSurfactants do not only influence the wetting/dewetting behavior of liquids, but also the impact behavior of drops on free-standing films or solutions. In a further part of this work, I dealt with the stability of the air cushion between drop and film/solution. To allow coalescence between drop and substrate, the air cushion has to vanish. In the presence of surfactants, the vanishing of the air is slowed down due to a change in the boundary condition from slip to no-slip, i. e. coalescence is suppressed or slowed down in the presence of surfactant.

Das GAF-Domänen-Protein NreA : ein neuartiger Nitratrezeptor aus Staphylococcus carnosus

Staphylococcus carnosus ist ein fakultativ anaerobes Bakterium, das aerobe Atmung, anaerobe Nitratatmung und Gärungsstoffwechsel betreiben kann. Die Expression des Nitratstoffwechsels wird durch das Dreikomponentensystem NreABC reguliert.rnUnter anaeroben Bedingungen besitzt die Sensorhistidinkinase NreB in ihrer PAS-Domäne ein [Fe4S4]2+-Cluster. Das aktive (anaerobe) [Fe4S4]2+-NreB überträgt nach Autophosphorylierung die Phosphorylgruppe auf den Antwortregulator NreC, welcher dann die Expression der Gene der Nitratatmung aktiviert. Nitrat wirkt mit Hilfe des NreA-Proteins auf diese Gene induzierend. Im Rahmen der vorliegenden Arbeit wurde gezeigt, dass NreA ein GAF-Domänen-Protein und ein neuartiger Nitratrezeptor ist.rnDie Natur von NreA als GAF-Domänen-Protein bestätigte sich beim Vergleich der Kristallstruktur mit denen anderer GAF-Domänen. GAF-Domänen sind weit verbreitet und binden typischer Weise kleine Moleküle. Als physiologischer Ligand von NreA zeigte sich Nitrat, das innerhalb einer definierten Bindetasche gebunden wird. NreA bindet vermutlich in dimerer Form an dimeres NreB und inhibiert dadurch die Phosphorylierung der Sensorhistidinkinase NreB. Die Interaktion von NreA mit NreB wurde in vivo durch BACTH-Messungen und sowohl in vivo als auch in vitro durch Cross-Linking Experimente gezeigt. Nitrat reduziert den Ergebnissen nach die Interaktion von NreA mit NreB.rnDurch Sequenzvergleiche von NreA mit Homologen wurden konservierte Aminosäuren identifiziert. Über gerichtete Mutagenese wurden 25 NreA-Varianten hergestellt und bezüglich ihres Verhaltens in Abhängigkeit von Nitrat in narG-lip-Reportergenstudien getestet. Anhand ihres Phänotyps wurden sie als Wildtyp, NreA- und NreABC-Mutanten klassifiziert. Die Nitratbindetasche war in sechs Fällen betroffen. Die Phänotypen der Mutationen in der Peripherie lassen sich mit Auswirkungen auf die vermutete Konformationsänderung oder auf die Interaktion mit NreB erklären. Mutationen von konservierten, oberflächenexponierten Resten führten vermehrt zu NreA/ON-Varianten. Es ließen sich Bereiche auf der Proteinoberfläche identifizieren, die für NreA/NreA- oder NreA/NreB-Interaktionen wichtig sein könnten.rnDie Untersuchungen zeigten, dass NreA mit NreB interagiert und dass dadurch ein NreA/NreB-Sensorkomplex für die gemeinsame Erkennung von Nitrat und Sauerstoff gebildet wird.

Nanofiber-based spectroscopy of organic molecules

This thesis reports on the experimental realization of nanofiber-based spectroscopy of organic molecules. The light guided by subwavelength diameter optical nanfibers exhibits a pronounced evanescent field surrounding the fiber which yields high excitation and emission collection efficiencies for molecules on or near the fiber surface.rnThe optical nanofibers used for the experiments presented in this thesis are realized as thernsub-wavelength diameter waist of a tapered optical fiber (TOF). The efficient transfer of thernlight from the nanofiber waist to the unprocessed part of the TOF depends critically on therngeometric shape of the TOF transitions which represent a nonuniformity of the TOF. Thisrnnonuniformity can cause losses due to coupling of the fundamental guided mode to otherrnmodes which are not guided by the taper over its whole length. In order to quantify the lossrnfrom the fundamental mode due to tapering, I have solved the coupled local mode equationsrnin the approximation of weak guidance for the three layer system consisting of fiber core andrncladding as well as the surrounding vacuum or air, assuming the taper shape of the TOFsrnused for the experiments presented in this thesis. Moreover, I have empirically studied therninfluence of the TOF geometry on its transmission spectra and, based on the results, I haverndesigned a nanofiber-waist TOF with broadband transmission for experiments with organicrnmolecules.rnAs an experimental demonstration of the high sensitivity of nanofiber-based surface spectroscopy, I have performed various absorption and fluorescence spectroscopy measurements on the model system 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA). The measured homogeneous and inhomogeneous broadening of the spectra due to the interaction of the dielectric surface of the nanofiber with the surface-adsorbed molecules agrees well with the values theoretically expected and typical for molecules on surfaces. Furthermore, the self-absorption effects due to reasorption of the emitted fluorescence light by circumjacent surface-adsorbed molecules distributed along the fiber waist have been analyzed and quantified. With time-resolved measurements, the reorganization of PTCDA molecules to crystalline films and excimers can be observed and shown to be strongly catalyzed by the presence of water on the nanofiber surface. Moreover, the formation of charge-transfer complexes due to the interaction with localized surface defects has been studied. The collection efficiency of the molecular emission by the guided fiber mode has been determined by interlaced measurements of absorption and fluorescence spectra to be about 10% in one direction of the fiber.rnThe high emission collection efficiency makes optical nanofibers a well-suited tool for experiments with dye molecules embedded in small organic crystals. As a first experimental realization of this approach, terrylene-doped para-terphenyl crystals attached to the nanofiber-waist of a TOF have been studied at cryogenic temperatures via fluorescence and fluorescence excitation spectroscopy. The statistical fine structure of the fluorescence excitation spectrum for a specific sample has been observed and used to give an estimate of down to 9 molecules with center frequencies within one homogeneous width of the laser wavelength on average for large detunings from resonance. The homogeneous linewidth of the transition could be estimated to be about 190MHz at 4.5K.

[SPECT/CT diagnostics for skeletal infections]

CLINICAL/METHODICAL ISSUE: Skeletal infections are often a diagnostic and clinical challenge. STANDARD RADIOLOGICAL METHODS: Nuclear imaging modalities used in the diagnostic workup of acute and chronic skeletal infections include three-phase bone scintigraphy and scintigraphy with labelled leucocytes. METHODICAL INNOVATIONS: The introduction of hybrid technologies, such as single photon emission computed tomography/computed tomography (SPECT/CT) has dramatically changed nuclear medical imaging of infections. PERFORMANCE: In general SPECT/CT leads to a considerably more accurate diagnosis than planar or SPECT imaging. ACHIEVEMENTS: Given the integrated acquisition of metabolic, functional and morphological information, SPECT/CT has increased in particular the specificity of three-phase skeletal scanning and scintigraphy with labeled leucocytes.

The treatment of spasticity with Delta9-tetrahydrocannabinol in persons with spinal cord injury

STUDY DESIGN: Open label study to determine drug dose for a randomized double-blind placebo-controlled parallel study. OBJECTIVES: To assess the efficacy and side effects of oral Delta(9)-tetrahydrocannabinol (THC) and rectal THC-hemisuccinate (THC-HS) in SCI patients. SETTING: REHAB Basel, Switzerland. METHOD: Twenty-five patients with SCI were included in this three-phase study with individual dose adjustment, each consisting of 6 weeks. Twenty-two participants received oral THC open label starting with a single dose of 10 mg (Phase 1, completed by 15 patients). Eight subjects received rectal THC-HS (Phase 2, completed by seven patients). In Phase 3, six patients were treated with oral THC and seven with placebo. Major outcome parameters were the spasticity sum score (SSS) using the Modified Ashworth Scale (MAS) and self-ratings of spasticity. RESULTS: Mean daily doses were 31 mg with THC and 43 mg with THC-HS. Mean SSS for THC decreased significantly from 16.72 (+/-7.60) at baseline to 8.92 (+/-7.14) on day 43. Similar improvement was seen with THC-HS. We observed a significant improvement of SSS with active drug (P=0.001) in the seven subjects who received oral THC in Phase 1 and placebo in Phase 3. Major reasons for drop out were increase of pain and psychological side effects. CONCLUSION: THC is an effective and safe drug in the treatment of spasticity. At least 15-20 mg per day were needed to achieve a therapeutic effect.

Atovaquone inhibits the glucuronidation and increases the plasma concentrations of zidovudine

The pharmacokinetic interaction between atovaquone, a 1,4-hydroxynaphthoquinone, and zidovudine was examined in an open, randomized, three-phase crossover study in 14 patients infected with human immunodeficiency virus. Atovaquone (750 mg every 12 hours) and zidovudine (200 mg every 8 hours) were given orally alone and in combination. Atovaquone significantly increased the area under the zidovudine concentration-time curve (AUC) (1.82 +/- 0.62 micrograms.hr/ml versus 2.39 +/- 0.68 micrograms.hr/ml; p < 0.05) and decreased the oral clearance of zidovudine (2029 +/- 666 ml/min versus 1512 +/- 464 ml/min; p < 0.05). In contrast, atovaquone tended to decrease the AUC of zidovudine-glucuronide (7.31 +/- 1.51 micrograms.hr/ml versus 6.89 +/- 1.42 micrograms.hr/ml; p < 0.1) and significantly decreased the ratio of AUC zidovudine-glucuronide/AUC zidovudine (4.48 +/- 1.94 versus 3.12 +/- 1.1; p < 0.05). The maximum concentration of zidovudine-glucuronide was significantly lowered by atovaquone (5.7 +/- 1.5 versus 4.57 +/- 0.97 micrograms/ml; p < 0.05). Zidovudine had no effect on the pharmacokinetic disposition of atovaquone. Atovaquone appears to increase the AUC of zidovudine by inhibiting the glucuronidation of zidovudine.

Methodological approach to the first and second lactate threshold in incremental cardiopulmonary exercise testing

Determination of an 'anaerobic threshold' plays an important role in the appreciation of an incremental cardiopulmonary exercise test and describes prominent changes of blood lactate accumulation with increasing workload. Two lactate thresholds are discerned during cardiopulmonary exercise testing and used for physical fitness estimation or training prescription. A multitude of different terms are, however, found in the literature describing the two thresholds. Furthermore, the term 'anaerobic threshold' is synonymously used for both, the 'first' and the 'second' lactate threshold, bearing a great potential of confusion. The aim of this review is therefore to order terms, present threshold concepts, and describe methods for lactate threshold determination using a three-phase model with reference to the historical and physiological background to facilitate the practical application of the term 'anaerobic threshold'.

Kalman Filter approaches on crane swing

The purpose of this study is to explore a Kalman Filter approach to estimating swing of crane-suspended loads. Measuring real-time swing is needed to implement swing damping control strategies where crane joints are used to remove energy from a swinging load. The typical solution to measuring swing uses an inertial sensor attached to the hook block. Measured hook block twist is used to resolve the other two sensed body rates into tangential and radial swing. Uncertainty in the twist measurement leads to inaccurate tangential and radial swing calculations and ineffective swing damping. A typical mitigation approach is to bandpass the inertial sensor readings to remove low frequency drift and high frequency noise. The center frequency of the bandpass filter is usually designed to track the load length and the pass band width set to trade off performance with damping loop gain. The Kalman Filter approach developed here allows all swing motions (radial, tangential and twist) to be measured without the use of a bandpass filter. This provides an alternate solution for swing damping control implementation. After developing a Kalman Filter solution for a two-dimensional swing scenario, the three-dimensional system is considered where simplifying assumptions, suggested by the two-dimensional study, are exploited. One of the interesting aspects of the three-dimensional study is the hook block twist model. Unlike the mass-independence of a pendulum's natural frequency, the twist natural frequency depends both on the pendulum length and the load’s mass distribution. The linear Kalman Filter is applied to experimental data demonstrating the ability to extract the individual swing components for complex motions. It should be noted that the three-dimensional simplifying assumptions preclude the ability to measure two "secondary" hook block rotations. The ability to segregate these motions from the primary swing degrees of freedom was illustrated in the two-dimensional study and could be included into the three-dimensional solution if they were found to be important for a particular application.