Numerical tests of an adaptive sectioned airfoil actuated by shape memory alloys

The main objective of this work is to illustrate an application of angular active control in a sectioned airfoil using shape memory alloys. In the proposed model, one wants to establish the shape of the airfoil profile based on the determination of an angle between its two sections. This angle is obtained by the effect of the shape memory of the alloy by passing an electric current that modifies the temperature of the wire through the Joule effect, changing the shape of the alloy. This material is capable of converting thermal energy into mechanical energy and once permanently deformed, the material can return to its original shape by heating. Due to the presence of nonlinear effects, especially in the mathematical model of the alloy, this work proposes the application of a control system based on fuzzy logic. Through numerical tests, the performance of the fuzzy controller is compared with an on-off controller applied in a sectioned airfoil model.

Interferência Fano antissimétrica assistida por um férmion de Majorana

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vibração de plantas de pimenta Malagueta para produção de frutos e sementes em ambiente protegido

This study aimed to verify the effect of vibration of plants in the production of fruits and seeds and in the physiological quality of the seeds of the “Malagueta” pepper in a protected cultivated area with open and closed sides. The experiment was conducted at the Experimental Farm of the School of Agronomic Sciences of Universidade Estadual Paulista (FCA/UNESP), located in the city of São Manuel (SP). Two treatments were carried out, which consisted of plants that did and did not undergo vibration. Plants were vibrated manually by swinging the wire attached to the supporting bamboo for about 5 seconds, twice a day for 11 weeks. The design was a randomized block with six repetitions. The same experiment was conducted in two protected environments, with and without anti-aphids screens on the sides, cultivated in the same season. For the comparison of environments, a combined analysis was performed considering each environment as a separate experiment. The characteristics evaluated were: weight and number of fruits per plant; weight, diameter and length of fruit; weight and amount of seeds per fruit; and plant height. For the analysis of seed quality, the characteristics evaluated were: germination percentage; first count of germination; dry matter of seedlings; seedling emergence in substrate; and seedling emergence speed index. Regardless of the environment, vibration affects the physiological quality of seeds. The presence of pollinator insects benefited the production and quality of “Malagueta” pepper seeds and increases the fruit weight.

Análise microestrutural e caracterização mecânica do aço AISI 4350 submetido a diferentes tratamentos térmicos

The multiphase steels are gaining increasing attention in scientific studies because of the different mechanical and microstructural properties that the material can achieve under different thermomechanical and heat treatments that can be submitted. In the present study, it was made a microstructural study thru the triple attack technic associated with optical microscopy and mechanical characterization of medium carbon AISI 4350 steel thru a tensile strength test, subjected to three routes of heat treatment: annealing, quenching and tempering and isothermal annealing. It was verified the predominance of ferrite-perlite constituent in the specimen annealed, martensitic in the quenched and tempered specimen and bainitic in the annealed isothermally specimen. The annealed material showed a higher ductility, while the hardened and tempered specimen showed the highest hardness and ultimately the bainitic specimen showed a combination of the two abovementioned mechanical properties. Thus, we proved that the multiphase steel SAE 4350 can be a versatile material with great potential for various industrial applications

Análise microestrutural e caracterização mecânica do aço AISI 4350 submetido a diferentes tratamentos térmicos

The multiphase steels are gaining increasing attention in scientific studies because of the different mechanical and microstructural properties that the material can achieve under different thermomechanical and heat treatments that can be submitted. In the present study, it was made a microstructural study thru the triple attack technic associated with optical microscopy and mechanical characterization of medium carbon AISI 4350 steel thru a tensile strength test, subjected to three routes of heat treatment: annealing, quenching and tempering and isothermal annealing. It was verified the predominance of ferrite-perlite constituent in the specimen annealed, martensitic in the quenched and tempered specimen and bainitic in the annealed isothermally specimen. The annealed material showed a higher ductility, while the hardened and tempered specimen showed the highest hardness and ultimately the bainitic specimen showed a combination of the two abovementioned mechanical properties. Thus, we proved that the multiphase steel SAE 4350 can be a versatile material with great potential for various industrial applications

Self-potential signals from an analog biogeobattery mode

A tank experiment was conducted to check if self-potential (SP) signals can be generated when buried organic matter is wire-connected to a near-surface, oxygen-rich, sediment layer. This experiment demonstrated that once wired, there was a flux of electrons (hence an electric current) between the lower and upper layers of the sandbox with the system responding as a large-scale microbial fuel cell (a type of bioelectrochemical system). An electric current was generated by this process in the wire and the SP method was used to monitor the associated electric potential distribution at the top of the tank.. The electric field was controlled by the flux of electrons through the wire, the oxidation of the organic matter, the reduction of oxygen used as a terminal electron acceptor, and the distribution of the DC resistivity in the tank. The current density through the wire was limited by the availability of oxygen and not by the oxidation of the organic matter. This laboratory experiment incorporated key elements of the biogeobattery observed in some organic-rich contaminant plumes. This analogy includes the generation of SP signals associated with a flux of electrons, the capacity of buried organic matter in sustaining anodic reactions, network resistance connecting terminal redox reactions spatially separated in space, and the existence of anodic secondary coupled reactions. A resistivity tomogram of the tank, after almost a year in operation, suggests that oxidative processes triggered by this geobattery can be imaged with this method to determine the radius of influence of the bioelectrochemical system.

Etablierung von Expressionsystemen für Gene der Indolalkaloid-Biosynthese unter besonderer Berücksichtigung von Cytochrom P450-Enzymen

Etablierung von Expressionsystemen für Gene der Indolalkaloid-Biosynthese unter besonderer Berücksichtigung von Cytochrom P450-Enzymen In der vorliegenden Arbeit wurden Enzyme aus der Arzneipflanze Rauvolfia serpentina bearbeitet. Es wurde versucht, das an der Biosynthese des Alkaloids Ajmalin beteiligte Cytochrom P450-Enzym Vinorin-Hydroxylase heterolog und funktionell zu exprimieren. Ein zunächst unvollständiger, unbekannter Cytochrom P450-Klon konnte komplettiert und eindeutig mittels heterologer Expression in sf9-Insektenzellen als Cinnamoyl-Hydroxylase identifiziert werden. Die Tauglichkeit des Insektenzellsystems für die Untersuchung der Vinorin-Hydroxylase ist auf Grund der deacetylierenden Wirkung der Insektenzellen auf das Substrat Vinorin nicht gegeben. Im Rahmen des Homology Cloning Projektes konnten mehrere Volllängenklone und diverse Teilsequenzen von neuen Cytochrom P450-Klonen ermittelt werden. Ausserdem wurde durch das unspezifische Binden eines degenerierten Primers ein zusätzlicher Klon gefunden, der der Gruppe der löslichen Reduktasen zugeordnet werden konnte. Diese putative Reduktase wurde auf die Aktivität von mehreren Schlüsselenzymen der Ajmalin-Biosynthese durch heterologe Expression in E.coli und anschliessende HPLC-gestützte Aktivitätstests ohne Erfolg geprüft. Bedingt durch die Untauglichkeit des Insektenzellsystems für die Identifizierung der Vinorin-Hydroxylase, wurde ein neuartiges Modul-gestütztes, pflanzliches Expressionsystem etabliert, um vorhandene P450-Volllängenklone auf Vinorin- Hydroxylaseaktivität testen zu können. Die Funktionalität des Systems konnte durch die heterologe Expression der Polyneuridinaldehyd Esterase bestätigt werden. Trotzdem war es bis jetzt nicht möglich, die Cinnamoyl-Hydroxylase als Kontrollenzym für das pflanzliche System oder aber die gesuchte Vinorin- Hydroxylase in aktiver Form zu exprimieren.

Accidental entrapment of an endo-bronchial blocker tip by a surgical stapler during selective ventilation for lung lobectomy in a dog

OBJECTIVE: To describe the use of an endobronchial blocker (EBB) and to perform selective ventilation during pulmonary lobe resection via thoracotomy in a dog and report its accidental stapling in the resection site. STUDY DESIGN: Clinical case report. ANIMAL: One female dog with a suspected abscess or neoplasia of the right caudal pulmonary lobe. METHODS: One-lung ventilation was performed using a wire-guided EBB to seal the contaminated parenchyma and facilitate surgical access. The affected lung parenchyma was resected and the resection site was closed with staples. RESULTS: Lobar resection was performed successfully, but the loop of the EBB guide wire was inadvertently entrapped in the staple line of the lobectomy. Staples were removed to release the wire loop, and the resulting air leak caused loss of ventilation control until the parenchyma was re-sealed. CONCLUSIONS: We recommend removing the wire guide associate with the EBB after successful lung separation to avoid accidents that could have life-threatening consequences if not recognized. CLINICAL RELEVANCE: One-lung ventilation is useful to isolate healthy parenchyma from diseased parenchyma during lobectomy. Anesthesiologists and surgeons need to be aware of the potential complications associated with use of EBB.

Stent grafting of acute hepatic artery bleeding following pancreatic head resection

The purpose of this study was to report the potential of hepatic artery stent grafting in cases of acute hemorrhage of the gastroduodenal artery stump following pancreatic head resection. Five consecutive male patients were treated because of acute, life-threatening massive bleeding. Instead of re-operation, emergency angiography, with the potential of endovascular treatment, was performed. Because of bleeding from the hepatic artery, a stent graft (with the over-the-wire or monorail technique) was implanted to control the hemmorhage by preserving patency of the artery. The outcome was evaluated. In all cases, the hepatic artery stent grafting was successfully performed, and the bleeding was immediately stopped. Clinically, immediately after the procedure, there was an obvious improvement in the general patient condition. There were no immediate procedure-related complications. Completion angiography (n=5) demonstrated control of the hemorrhage and patency of the hepatic artery and the stent graft. Although all patients recovered hemodynamically, three individuals died 2 to 10 days after the procedure. The remaining two patients survived, without the need for re-operation. Transluminal stent graft placement in the hepatic artery is a safe and technically feasible solution to control life-threatening bleeding of the gastroduodenal artery stump.

Controlling electronic and magnetic properties of ultra narrow multilayered nanowires

Interest in the study of magnetic/non-magnetic multilayered structures took a giant leap since Grünberg and his group established that the interlayer exchange coupling (IEC) is a function of the non-magnetic spacer width. This interest was further fuelled by the discovery of the phenomenal Giant Magnetoresistance (GMR) effect. In fact, in 2007 Albert Fert and Peter Grünberg were awarded the Nobel Prize in Physics for their contribution to the discovery of GMR. GMR is the key property that is being used in the read-head of the present day computer hard drive as it requires a high sensitivity in the detection of magnetic field. The recent increase in demand for device miniaturization encouraged researchers to look for GMR in nanoscale multilayered structures. In this context, one dimensional(1-D) multilayerd nanowire structure has shown tremendous promise as a viable candidate for ultra sensitive read head sensors. In fact, the phenomenal giant magnetoresistance(GMR) effect, which is the novel feature of the currently used multilayered thin film, has already been observed in multilayered nanowire systems at ambient temperature. Geometrical confinement of the supper lattice along the 2-dimensions (2-D) to construct the 1-D multilayered nanowire prohibits the minimization of magnetic interaction- offering a rich variety of magnetic properties in nanowire that can be exploited for novel functionality. In addition, introduction of non-magnetic spacer between the magnetic layers presents additional advantage in controlling magnetic properties via tuning the interlayer magnetic interaction. Despite of a large volume of theoretical works devoted towards the understanding of GMR and IEC in super lattice structures, limited theoretical calculations are reported in 1-D multilayered systems. Thus to gauge their potential application in new generation magneto-electronic devices, in this thesis, I have discussed the usage of first principles density functional theory (DFT) in predicting the equilibrium structure, stability as well as electronic and magnetic properties of one dimensional multilayered nanowires. Particularly, I have focused on the electronic and magnetic properties of Fe/Pt multilayered nanowire structures and the role of non-magnetic Pt spacer in modulating the magnetic properties of the wire. It is found that the average magnetic moment per atom in the nanowire increases monotonically with an ~1/(N(Fe)) dependance, where N(Fe) is the number of iron layers in the nanowire. A simple model based upon the interfacial structure is given to explain the 1/(N(Fe)) trend in magnetic moment obtained from the first principle calculations. A new mechanism, based upon spin flip with in the layer and multistep electron transfer between the layers, is proposed to elucidate the enhancement of magnetic moment of Iron atom at the Platinum interface. The calculated IEC in the Fe/Pt multilayered nanowire is found to switch sign as the width of the non-magnetic spacer varies. The competition among short and long range direct exchange and the super exchange has been found to play a key role for the non-monotonous sign in IEC depending upon the width of the Platinum spacer layer. The calculated magnetoresistance from Julliere's model also exhibit similar switching behavior as that of IEC. The universality of the behavior of exchange coupling has also been looked into by introducing different non-magnetic spacers like Palladium, Copper, Silver, and Gold in between magnetic Iron layers. The nature of hybridization between Fe and other non-magnetic spacer is found to dictate the inter layer magnetic interaction. For example, in Fe/Pd nanowire the d-p hybridization in two spacer layer case favors anti-ferromagnetic (AFM) configuration over ferromagnetic (FM) configuration. However, the hybridization between half-filled Fe(d) and filled Cu(p) state in Fe/Cu nanowire favors FM coupling in the 2-spacer system.

Quantum transport in a single molecular junction

The craze for faster and smaller electronic devices has never gone down and this has always kept researchers on their toes. Following Moore’s law, which states that the number of transistors in a single chip will double in every 18 months, today “30 million transistors can fit into the head of a 1.5 mm diameter pin”. But this miniaturization cannot continue indefinitely due to the ‘quantum leakage’ limit in the thickness of the insulating layer between the gate electrode and the current carrying channel. To bypass this limitation, scientists came up with the idea of using vastly available organic molecules as components in an electronic device. One of the primary challenges in this field was the ability to perform conductance measurements across single molecular junctions. Once that was achieved the focus shifted to a deeper understanding of the underlying physics behind the electron transport across these molecular scale devices. Our initial theoretical approach is based on the conventional Non-Equilibrium Green Function(NEGF) formulation, but the self-energy of the leads is modified to include a weighting factor that ensures negligible current in the absence of a molecular pathway as observed in a Mechanically Controlled Break Junction (MCBJ) experiment. The formulation is then made parameter free by a more careful estimation of the self-energy of the leads. The calculated conductance turns out to be atleast an order more than the experimental values which is probably due to a strong chemical bond at the metal-molecule junction unlike in the experiments. The focus is then shifted to a comparative study of charge transport in molecular wires of different lengths within the same formalism. The molecular wires, composed of a series of organic molecules, are sanwiched between two gold electrodes to make a two terminal device. The length of the wire is increased by sequentially increasing the number of molecules in the wire from 1 to 3. In the low bias regime all the molecular devices are found to exhibit Ohmic behavior. However, the magnitude of conductance decreases exponentially with increase in length of the wire. In the next study, the relative contribution of the ‘in-phase’ and the ‘out-of-phase’ components of the total electronic current under the influence of an external bias is estimated for the wires of three different lengths. In the low bias regime, the ‘out-of-phase’ contribution to the total current is minimal and the ‘in-phase’ elastic tunneling of the electrons is responsible for the net electronic current. This is true irrespective of the length of the molecular spacer. In this regime, the current-voltage characteristics follow Ohm’s law and the conductance of the wires is found to decrease exponentially with increase in length which is in agreement with experimental results. However, after a certain ‘off-set’ voltage, the current increases non-linearly with bias and the ‘out-of-phase’ tunneling of electrons reduces the net current substantially. Subsequently, the interaction of conduction electrons with the vibrational modes as a function of external bias in the three different oligomers is studied since they are one of the main sources of phase-breaking scattering. The number of vibrational modes that couple strongly with the frontier molecular orbitals are found to increase with length of the spacer and the external field. This is consistent with the existence of lowest ‘off-set’ voltage for the longest wire under study.

Betriebsdauer von Drahtseilen beim Lauf über Kunststoff-Seilrollen

Kunststoff-Seilrollen sind leichter als Stahl-Seilrollen, woraus für die Konstruktion, besonders von Auslegerkranen, Vorteile erwachsen. Kunststoff-Seilrollen bringen aber auch Vorteile für das Seil selbst, weil sich dessen Lebensdauer vergrößert. Dieser Lebensdauergewinn wurde durch umfassende experimentelle und theoretische Untersuchungen zum Einfluss von Kunststoff-Seilrollen auf die Drahtseillebensdauer quantifiziert und begründet. Zur sicherheitstechnischen Beherrschung von Seiltrieben mit Kunststoff-Seilrollen wird eine Online-Schadensakkumulation vorgeschlagen.

Rechnergestützte Analyse von mehrfach eingescherten Seiltrieben

Die Bestimmung der Anzahl der Biegewechsel von laufenden Drahtseilen ist ein wesentlicher Bestandteil bei der Betriebsdaueranalyse von Seiltrieben. Auf Seilabschnitte, die während der Betriebszeit die meisten Biegewechsel erfahren, sollte bei einer Seilprüfung besonderes Augenmerk gelegt werden. Gerade bei mehrfacher Einscherung ist jedoch nicht immer von vorn herein ersichtlich, um welche Seilabschnitte es sich dabei handelt. Auf der Basis der Geometrie des mehrfach eingescherten Seiltriebs wird ein rechnergestütztes Analyseverfahren zur Ermittlung der Anzahl der Biegewechsel entlang des Drahtseils bei einem Arbeitsspiel vorgestellt.

A comparative assessment of torque generated by lingual and conventional brackets

The aim of this study was to assess the effect of bracket type on the labiopalatal moments generated by lingual and conventional brackets. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), In-Ovation L lingual brackets (DENTSPLY GAC), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on identical maxillary acrylic resin models with levelled and aligned teeth. Each model was mounted on the orthodontic measurement and simulation system and 10 0.0175 × 0.0175 TMA wires were used for each bracket type. The wire was ligated with elastomerics into the Incognito, STb, and conventional brackets and each measurement was repeated once after religation. A 15 degrees buccal root torque (+15 degrees) and then a 15 degrees palatal root torque (-15 degrees) were gradually applied to the right central incisor bracket. After each activation, the bracket returned to its initial position and the moments in the sagittal plane were recorded during these rotations of the bracket. One-way analysis of variance with post hoc multiple comparisons (Tukey test at 0.05 error rate) was conducted to assess the effect on bracket type on the generated moments. The magnitude of maximum moment at +15 degrees ranged 8.8, 8.2, 7.1, and 5.8 Nmm for the Incognito, STb, conventional Gemini, and the In-Ovation L brackets, respectively; similar values were recorded at -15 degrees: 8.6, 8.1, 7.0, and 5.7 Nmm, respectively. The recorded differences of maximum moments were statistically significant, except between the Incognito and STb brackets. Additionally, the torque angles were evaluated at which the crown torque fell well below the minimum levels of 5.0 Nmm, as well as the moment/torque ratio at the last part of the activation/deactivation curve, between 10 and 15 degrees. The lowest torque expression was observed at the self-ligating lingual brackets, followed by the conventional brackets. The Incognito and STb lingual brackets generated the highest moments.

A comparative assessment of forces and moments generated by lingual and conventional brackets

The aim of this study was to assess the effect of bracket type on the labiopalatal forces and moments generated in the sagittal plane. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on three identical maxillary acrylic resin models, with a palatally displaced right lateral incisor. The transfer trays for the indirect bonding of the lingual brackets were constructed in certified laboratories. Each model was mounted on the orthodontic measurement and simulation system and ten 0.013 inch CuNiTi wires were used for each bracket type. The wire was ligated with elastomerics and each measurement was repeated once after re-ligation. The labiopalatal forces and the moments in the sagittal plane were recorded on the right lateral incisor. One-way analysis of variance and post hoc Scheffe pairwise comparisons were used to assess the effect on bracket type on the generated forces and moments. The magnitude of forces ranged from 1.62, 1.27, and 1.81 N for the STb, conventional, and Incognito brackets, respectively; the corresponding moments were 2.01, 1.45, and 2.19 N mm, respectively. Bracket type was a significant predictor of the generated forces (P < 0.001) and moments (P < 0.001). The produced forces were different among all three bracket types, whereas the generated moments differed between conventional and lingual brackets but not between lingual brackets.