Ce travail est consacré à la recherche de nouveaux matériaux sans plomb à structure pérovskite, de formules (A⁺,Bi³⁺)BO₃ et (A⁺,Bi³+)(B,B’)O₃ où A⁺ = {Li⁺, Na⁺, K⁺, Rb⁺}. Le but visé est le remplacement des pérovskites à base de plomb actuellement utilisées dans les dispositifs électroniques. La possibilité de substitution du plomb par un pseudo-ion (A⁺,Bi³⁺) a été étudiée pour (i) les pérovskites simples PbTiO₃ et PbZrO₃ et (ii) les pérovskites complexes Pb(Mg⅟₃Nb⅔)O₃ et Pb(Zn⅟₃Nb⅔)O₃.La synthèse de la composition (Li⅟₂Bi⅟₂)TiO₃ (LBT) a conduit à un composé pyrochlore de type Bi₂Ti₂O₇. Les autres compositions ont permis d'obtenir les pérovskites (Na⅟₂Bi⅟₂)ZrO₃ (NBZ), (K⅟₂Bi⅟₂)ZrO₃ (KBZ), (Na⅟₂Bi⅟₂)(Mg⅓Nb⅔)O₃ (NBMN), (K⅟₂Bi⅟₂)(Mg⅟₃Nb⅔)O₃ (KBMN) et (K⅟₂Bi⅟₂)(Zn⅟₃Nb⅔)O₃ (KBZN). Un important travail de synthèse a été effectué, en utilisant plusieurs voies et différents précurseurs, afin d'essayer d'éliminer les phases secondaires qui accompagnent généralement ces pérovskites.Les structures cristallines ont été étudiées par diffraction de neutrons à l'aide de la méthode de Rietveld. Celles-ci ont été déterminées pour LBT, NBZ, KBZ et KBMN. Les propriétés électriques de ces matériaux ont également été étudiées. Aucun d'entre eux n'est ferroélectrique. KBZ est électrostrictif. Enfin, NBZ, NBMN et KBMN montrent d'intéressantes propriétés de relaxeurs. / The present work focused on the research of new lead-free perovskite materials with the formula (A⁺,Bi³⁺)BO₃ and(A⁺,Bi³+)(B,B’)O₃ with A⁺ = {Li⁺, Na⁺, K⁺, Rb⁺}. The aim of this study is to find potential candidates to replace the lead-based perovskite used in the electronic devices nowadays. The possibility to substitute the lead ion par a couple (A⁺,Bi³⁺) has been examined for (i) the simple perovskites PbTiO₃ and PbZrO₃ and (ii) the complex perovskites Pb(Mg⅟₃Nb⅔)O₃ and Pb(Zn⅟₃Nb⅔)O₃.The synthesis of the composition (Li⅟₂Bi⅟₂)TiO₃ (LBT) has led to a pyrochlore Bi₂Ti₂O₇-like compound. The other compositions have conducted to the perovskites compounds (Na⅟₂Bi⅟₂)ZrO₃ (NBZ), (K⅟₂Bi⅟₂)ZrO₃ (KBZ), (Na⅟₂Bi⅟₂)(Mg⅓Nb⅔)O₃ (NBMN),(K⅟₂Bi⅟₂)(Mg⅟₃Nb⅔)O₃ (KBMN) and (K⅟₂Bi⅟₂)(Zn⅟₃Nb⅔)O₃ (KBZN). A lot of work has been carried out for the syntheses, using different precursor or process, in order to suppress the secondary phases which are often obtained with these perovskites. The crystalline structures have been studied by neutron diffraction, using the Rietveld method. These have been determined for the LBT, NBZ, KBZ and KBMN compounds. The electrical properties of these materials have also been studied. None of them is ferroelectric. KBZ is électrostrictif. Finally, NBZ, NBMN and KBMN present some interesting relaxor properties.

No description available.

Microfluidic technology is a rapidly progressing tool in biomedical engineering. Microfluidic devices are appreciated for their simplicity and production efficiency potential. Our research focuses on developing a microfluidic device capable of transfecting cells by applying shear stress to cause temporary membrane damage. The advantage of this physical method of transfection is the possibility of incorporating large molecules that cannot be inserted with more traditional chemical transfection methods, while avoiding the large fall in viability seen with other physical methods such as electroporation. Unlike previous groups, our device incorporates the use of microfluidic valves to allow tunability, and impedance sensing for cell membrane damage analysis. We achieve (95±5)% cell viability and up to (68±5)% efficiency in transfecting 3T3 cells with DNA-sized molecules. In future stages, we intend to add the device onto an existing cell-encapsulation device that is tasked with preparing therapeutic cells to be used in regenerative medicine applications.

Fracture of a pacemaker lead is one of the most common causes of pacemaker malfunction. Lead fractures are seen in approximately 4 % of patients with pacemakers. We present a rare case of complete severance of the tip of a dual chamber pacemaker atrial lead. A 62 years old male presented for a routine device check of his pacemaker, which was originally implanted in 2002 for sick sinus syndrome and had a generator change in 2010. Device check showed a dual chamber pacemaker with right atrial and right ventricular leads and a remaining battery life of 8.6 years. Patient was not pacemaker dependent. Ventricular lead showed normal sensing, impedance and pacing threshold. Atrial lead showed unusually high impedance of 2175 ohms and no capture on testing at voltages as high as 7.5 mV. Further evaluation was done due to abnormal atrial lead test. An EKG was obtained showing normal sinus rhythm and atrial pacing spikes with no capture. Chest X-ray revealed a complete severance and dislocation of the atrial lead tip and an intact ventricular lead. A detailed history was obtained, and patient denied any trauma to the chest or upper extremities, chest pain, shortness of breath, palpitations, syncope or presyncope. Upon further history, patient reported a recent visit to theme park and enjoying high thrill rides. On examination, there were no signs of trauma, erythema, swelling, warmth, drainage or erosion at implant site. The pacemaker setting was changed from DDDR to VVIR, with plans to cap the proximal port of the fractured lead and placing a new atrial lead. Pacemaker lead fractures are reported with an incidence rate of 0.1 to 4.2 % per patient year [1]. The most common site of lead fracture is at the site of entry (40%) followed by between the entry site and generator (28%), close to the generator site (23%) and only (7%) are intravascular fractures [1]. Trauma and subclavian crush syndrome are the most commonly reported causes of pacemaker lead fractures. Pacemaker lead fracture due to physical exertion is an uncommon cause of lead malfunction [2]. Few cases have been reported of traumatic lead fracture due to the blunt chest trauma [3]. Patients with a lead fracture may present with symptoms of dizziness, syncope, chest discomfort, palpitations or, less commonly extra cardiac symptoms like hiccups or may completely be asymptomatic as seen in our patient. Diagnosis can be made by electrogram during device check, ECG and careful review of chest imaging such as chest x ray or fluoroscopy. Treatment is placement of a new lead with or without extraction of the fractured lead. This rare case of pacemaker lead fracture after a theme park ride indicates there may be a risk to pacemaker leads with high velocity amusement park rides which are becoming popular. This may have clinical implications such as a need for caution during amusement park visits and routine pacemaker interrogations after such visits especially in pacemaker dependent patients. References: 1: Alt E, Völker R, Blömer H: Lead fracture in pacemaker patients. Thorac Cardiovasc Surg.1987, 35:101-4.10.1055/s-2007-1020206 2: ohm J: Displacement and fracture of pacemaker electrode during physical exertion. Report on three cases. Acta Med Scand.1972, 192:33-5.10.1111/j.0954-6820.1972.tb04774 3: Bőhm A1, Duray G, Kiss RG: Traumatic Pacemaker lead fracture. Emerg Med J.2013, 30:686.10.1136/emermed-2012-202090.

This research focuses on the creation, validation, automation, and deployment of a nondestructive vertical electrical impedance (VEI) bridge deck assessment apparatus. A multichannel impedance analyzer with a moving platform is developed that can assess the deterioration state of a bridge deck without stationary traffic control. The multichannel apparatus is capable of taking over 500 impedance samples a second and can scan a bridge deck over 500 times faster than more traditional techniques. This research also shows VEI measurements are inversely proportional to the diffusivity of ions through concrete and that an impedance measurement frequency of 25 kHz is the most predictive measurement frequency of diffusivity. Finally, this research demonstrates the utility of VEI measurements by inspecting five asphalt overlaid bridges. VEI measurements were sensitive to defects in membranes and are one of the only nondestructive measurements that provide useful information about the deterioration state of asphalt overlaid bridge decks.

Presently, there is no standard testing procedure for piezoelectric actuators. It is then very difficult for a very specific given application to design the most efficient actuator in terms of blocked force, displacement, power consumption, weight, cost, etc. Piezoelectric actuator suppliers would like to have the possibility to fully characterize their actuators to be able to guide their customers on selection of the most suitable actuator based on their utilization. However, this is not an easy goal to reach since performance of a given actuator depends on the specific dynamic conditions under which it is applied. In order to characterize an actuator, it is therefore necessary to recreate similar conditions to those experienced in the real application. Because of the infinite variety of possible applications for piezoelectric actuators, physically recreating those conditions could take an enormous amount of time, means and money. The aim of the research is then to develop the technology required in order to test an actuator under a various range of dynamic load conditions using a single automated test set-up. To do so, a second actuator will be used with a suitable sensing apparatus (impedance head) and an active control system. Using data from the sensing apparatus (force and velocity signals), the active control system will drive the second actuator to recreate any load condition the first actuator would be supposed to experience in a real application. <i>[Vita removed May 14, 2012. Gmc]</i> / Master of Science

1) Test the accuracy of the Welch Allyn Microtympanometer against standard tympanometry. 2) Correlate preoperative clinical findings with: • Microtympanometry • Standard tympanometry 3) Assess influence of induction by gas anaesthesia on: • Post-induction microtympanometry • Intraoperative myringotomy findings 4) Assess the practicality of using the Welch Allyn Microtympanometer as a screening tool in Pre-School audiological testing.

In the ocean, natural and artificial processes generate clouds of bubbles which scatter and attenuate sound. Measurements have shown that at the individual bubble resonance frequency, sound propagation in this medium is highly attenuated and dispersive. Theory to explain this behavior exists in the literature, and is adequate away from resonance. However, due to excessive attenuation near resonance, little experimental data exists for comparison. An impedance tube was developed specifically for exploring this regime. Using the instrument, unique phase speed and attenuation measurements were made for void fractions ranging from 6.2 × 10^−5 to 2.7 × 10^−3 and bubble sizes centered around 0.62 mm in radius. Improved measurement speed, accuracy and precision is possible with the new instrument, and both instantaneous and time-averaged measurements were obtained. Behavior at resonance was observed to be sensitive to the bubble population statistics and agreed with existing theory, within the uncertainty of the bubble population parameters. Scattering from acoustically compact bubble clouds can be predicted from classical scattering theory by using an effective medium description of the bubbly fluid interior. Experimental verification was previously obtained up to the lowest resonance frequency. A novel bubble production technique has been employed to obtain unique scattering measurements with a bubbly-liquid-filled latex tube in a large indoor tank. The effective scattering model described these measurements up to three times the lowest resonance frequency of the structure. / United States Navy Office of Naval Research Ocean Acoustics Program

No description available.

Radio Frequency Identification (RFID) systems use electromagnetic signals to wirelessly identify and track RFID-tagged objects. A reader transmits a carrier wave request signal to an RFID tag, which then transmits a unique identification signal back to the reader. Applications include supply chain inventory management, automated toll booth fee systems, sports event timing, restricted access control, pet monitoring and retail theft prevention. An RFID tag includes an antenna connected to a Radio Frequency Integrated Circuit (RFIC). RFID tags in the ultra-high frequency (UHF), industrial, scientific and medical (ISM) 902-928MHz band and global Electronic Product Code (EPC) 860‑960MHz band are powered passively (power extracted from carrier wave) and cost less than 15 cents per tag. Low cost UHF ISM RFID tags are an effective solution for tracking large inventories. UHF ISM tag antennas are typically planar dipoles printed onto a plastic dielectric substrate (inlay). Power exchange and transmit range is maximized when a tag antenna’s input impedance is conjugate matched to the RFIC input impedance. Since RFIC input impedance includes capacitive reactance, optimized antenna input impedance includes compensating inductive reactance. The T-match network adds inductive matching microstrips to conjugate match the RFIC. Narrowband (±1.5% of center frequency) and broadband (±5% of center frequency) lumped element designs also use inductive matching strips. Narrowband, lumped element design is accomplished through Smith Chart matching assuming lumped antenna elements. The broadband lumped element design is accomplished through a circuit transformation to an equivalent network and tuning the transformed circuit to resonate from 865MHz to 955MHz, with a center frequency of 910MHz. This thesis demonstrates a start-to-finish design process for narrow (±1.5% of center frequency) and broadband (±5% of center frequency) RFID tag antennas [3]. Furthermore, antenna matching element geometries are parametrically swept to characterize input impedance frequency response. Thesis accomplishments include (a) narrow and broadband antenna designs, (b) Keysight’s Advanced Design System (ADS) Momentum simulations, (c) antenna fabrication, and (d) differential probe impedance setup and antenna impedance measurements. Additional items include (e) impedance adjustments (f) tag range testing and (g) narrow vs. broadband matching technique comparisons. Antennas were fabricated in Cal Poly’s Graphic Communication Department by silk-screening silver conductive ink onto DuPont Melinix Polyethylene Terephthalate (PET) plastic. Impedance simulations are compared to fabricated antenna impedance measurements and range testing results.