Study of macroscopic and microscopic properties of liposomes produced using microfluidic methods

For the last decades, lipid vesicles or liposomes, vesicles formed by a bilayer of amphiphilic lipids, have been used as a toy model for studying the cell membrane and for applications in cosmetics and drug delivery. Traditional methods for producing liposomes face some problems such as the heterogeneity in size and composition of the liposomes produced. A few years ago, a novel method that produces liposomes with homogeneous size and composition was developed. This novel method is based on the use of water in oil in water ultra-thin double emulsions, with lipids dissolved in the oil phase, as templates for the liposome production. These ultra-thin double emulsions are produced using glass capillary microfluidic devices. This new method for producing liposomes seems very promising, but since the liposomes are formed by the oil phase evaporation of the double emulsions, the doubt that some residual oil in the bilayer may alter the properties of the liposomes appears. In this work different phenomena and properties of liposomes that have been studied for the ones produced using conventional methods are studied for liposomes produced using microfluidic methods. The microfluidic apprOutgoin

A 3D US Guidance System for Permanent Breast Seed Implantation: Development and Validation

Permanent breast seed implantation (PBSI) is a promising breast radiotherapy technique that suffers from operator dependence. We propose and have developed an intraoperative 3D ultrasound (US) guidance system for PBSI. A tracking arm mounted to a 3D US scanner registers a needle template to the image. Images were validated for linear and volumetric accuracy, and image quality in a volunteer. The tracking arm was calibrated, and the 3D image registered to the scanner. Tracked and imaged needle positions were compared to assess accuracy and a patient-specific phantom procedure guided with the system. Median/mean linear and volumetric error was ±1.1% and ±4.1%, respectively, with clinically suitable volunteer scans. Mean tracking arm error was 0.43mm and 3D US target registration error ≤0.87mm. Mean needle tip/trajectory error was 2.46mm/1.55°. Modelled mean phantom procedure seed displacement was 2.50mm. To our knowledge, this is the first reported PBSI phantom procedure with intraoperative 3D image guidance

Multi-scale volumetric dynamic optoacoustic and laser ultrasound (OPLUS) imaging enabled by semi-transparent optical guidance

Major biological discoveries have been made by interrogating living organisms with light. However, the limited penetration of unscattered photons within biological tissues severely limits the depth range covered by optical methods. Deep-tissue imaging has been achieved by combining light and ultrasound. Optoacoustic imaging uniquely exploits optical generation of ultrasound to render high-resolution images at depths unattainable with optical microscopy. Recently, laser ultrasound has further been suggested as a means of generating broadband acoustic waves for high-resolution pulse-echo ultrasound imaging. Herein, we propose an approach to simultaneously interrogate biological tissues with light and ultrasound based on layer-by-layer coating of silica optical fibers with a controlled degree of transparency. We exploit the time separation between optoacoustic signals and ultrasound echoes collected with a custom-made spherical array transducer for simultaneous three-dimensional optoacoustic and laser ultrasound (OPLUS) imaging with a single laser pulse. OPLUS is shown to enable large-scale comprehensive anatomical characterization of tissues along with functional multi-spectral imaging of spectrally-distinctive chromophores and assessment of cardiac dynamics at ultrafast rates only limited by the pulse repetition frequency of the laser. The suggested approach provides a flexible and scalable means for developing a new generation of systems synergistically combining the powerful capabilities of optoacoustics and ultrasound imaging in biology and medicine.Comment: 21 pages, 4 figure

Confocal Microscopy of Plant Cells

The increasing availability of confocal microscopy has begun a revolution in plant biology in which microscopy has again become a powerful tool for understanding structure and function. Examples of applications include: three dimensional (3D) reconstruction of the interphase microtubule array in large vacuolated epidermal cells (1); measuring cytoplasmic free calcium changes in whole maize coleoptile segments in response to phototropic and gravitropic stimuli (2); and studying symplastic phloem connections in intact Arabidopsis roots (3). The major reason for this revolution is the ability to collect clear images in three dimensions due to the lack of image degradation caused by out-of-focus light. Plant cells can attain very large sizes (hundreds of micrometers, in some cases) and are very thick. Thus the ability of the confocal microscope to obtain optical sections of tissues from which 3D reconstructions can be made surpasses the limitations of conventional “wide-field” microscopic techniques where microtome sectioning is often required and cells must be viewed as flat, two-dimensional objects. Furthermore, the reduction in out-of-focus flare increases depth discriminatio

Production of carbon nanotubes by PECVD and their applications to supercapacitors

Màster en Nanociència i NanotecnologiaPlasma enhanced chemical vapor deposition (PECVD) is a versatile technique to obtain vertically dense-aligned carbon nanotubes (CNTs) at lower temperatures than chemical vapor deposition (CVD). In this work, we used magnetron sputtering to deposit iron layer as a catalyst on silicon wafers. After that, radio frequency (rf) assisted PECVD reactor was used to grow CNTs. They were treated with water plasma and finally covered by MnO2 as dielectric layer in order to use CNTs as electrode for supercapacitors. Optimization of annealing time, reaction time and temperature, water plasma time and MnO2 deposition time were performed to find appropriate conditions to improve the characteristics of supercapacitors. SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), AFM (Atomic Force Microscopy) and Raman spectroscopy were used to characterize obtained electrodes

Ultrasound-Guided Mechatronic System for Targeted Delivery of Cell-Based Cancer Vaccine Immunotherapy in Preclinical Models

Injection of dendritic cell (DC) vaccines into lymph nodes (LN) is a promising strategy for eliciting immune responses against cancer, but these injections in mouse cancer models are challenging due to the small target scale (~ 1 mm × 2 mm). Direct manual intranodal injection is difficult and can cause architectural damage to the LN, potentially disrupting crucial interactions between DC and T cells. Therefore, a second-generation ultrasound-guided mechatronic device has been developed to perform this intervention. A targeting accuracy of \u3c 500 μm will enable targeted delivery of the DCs specifically to a LN subcapsular space. The device was redesigned from its original CT-guided edition, which used a remote centre of motion architecture, to be easily integrated onto a commercially available VisualSonics imaging rail system. Subtle modifications were made to ensure simple workflow that allows for live-animal interventions that fall within the knockout periods stated in study protocols. Several calibration and registration techniques were developed in order to achieve an overall targeting accuracy appropriate for the intended application. A variety of methods to quantify the positioning accuracy of the device were investigated. The method chosen involved validating a guided injection into a tissue-mimicking phantom using ultrasound imaging post-operatively to localize the end-point position of the needle tip in the track left behind by the needle. Ultrasound-guided injections into a tissue-mimicking phantom revealed a targeting accuracy of 285 ± 94 μm for the developed robot compared to 508 ± 166 μm for a commercial-available manually-actuated injection device from VisuailSonics. The utility of the robot was also demonstrated by performing in vivo injections into the lymph nodes of mice

Comparative evaluation of acoustic and electric signals of partial discharges

Failures of power electric components such as transformers and outages can lead to a huge economical loss in the electric power grid. One of the main parts of a power electric components is the insulation system, namely, insulation oil, impregnated pressboard and paper. Several methods exist for diagnostics of these insulation materials. Partial discharge (PD) measurement known as one of the main non-destructive monitoring systems of the insulation materials. However, it has been mainly done off-line in maintenance periods, and the existing on-line methods generally provide less information due to environment electric noises. In contrast to electric PD measurement system, the acoustic emission (AE) measurement system is well known for its immunity against environment electrical noises. In this thesis comparative evaluation of acoustic and electric signals of PD events generated in oil impregnated pressboard and papers is investigated. The thesis is focused on the characteristic of PD activity and the consequence of that on the electric and AE signal. PD classification is defined by using the relation between acoustic and electric signals of PD events. Although the sensitivity of the AE sensors has been improved over the years, but the detection of the acoustic signals from PD activity in power equipment mainly transformers remain the main challenge of acoustic measurement. Lack of information regarding evaluation of electric PD signals and AE signals beside the mechanical attenuation are two main disadvantages of AE measurement method. Due to mechanical and electrical mechanism of waves generated during PD activities, the mechanical and electrical behaviour of the waves is discussed in more detail to have better understanding about the electric and acoustic signals. PD sources were generated at different electrode configurations such as needle-plane and electrode ball arrangement within a sample in the tank to investigate different types of PD. Electric characteristics of PD and different PD measuring technics such as electric, UHF and acoustic beside the mechanical behaviour of the acoustic waves are also discussed. The corona in oil results regarding the relation between AE and electric PD signals shows the correlated behaviour between AE and PD apparent charge magnitude. However, in surface discharges these behaviours are uncorrelated. In this regards the surface discharge is studied in more detail, leading to the first results of PD with very low acoustic (no acoustic) activity. Regarding these results two different categories in term of AE signals of PDs are defined, silent PD and non-silent PD. Silent PDs are those PD activities without or with very low acoustic signal and non-silent PDs are with acoustic signal. The existence of the silent PD is validated via oscilloscope and digital signal processing (DSP) devices. Also, with different innovative methods and arrangements such as needle plane and ball electrodes with and without oil gap, the probable reasons of creation this phenomenon (silent PD) is investigated. It is found that the carbonization patterns start with non-silent PD and remain the same during silent PD activities even with very high electric apparent charges. It means the development in carbonization traces produce electric and AE signals and in contrast no changes in carbonization traces produce only electric signals with no AE signal. These results verify the advantages of using acoustic technics and electric measurement in terms of PD classification and localization.Ausfälle von Komponenten in elektrischen Energiesystemen wie Transformatoren können zu einem enormen wirtschaftlichen Verlust im Energiesystem führen. Einer der Hauptbestandteile der Komponenten in elektrischen Energiesystemen ist das Isoliersystem, nämlich Öl, imprägniert Pressboard und Papier. Es gibt mehrere Methoden zur Diagnose dieser Isoliermaterialien. Die Messung der Teilentladung (TE) ist als eines der wichtigsten zerstörungsfreien Überwachungssysteme für Isoliermaterialien bekannt. Jedoch wird dies in Wartungsperioden hauptsächlich offline durchgeführt, und die existierenden Online-Verfahren liefern im Allgemeinen weniger Informationen aufgrund von elektromagnetischen Störungen. Im Gegensatz zum elektrischen TE-Messsystem ist das Schallemissionsmesssystem für seine Immunität gegen elektrische Umgebungsgeräusche bekannt. In dieser Arbeit wird die vergleichende Auswertung von akustischen und elektrischen Signalen von TE-Ereignissen untersucht, die in ölimprägnierten Pressboard und Papieren erzeugt werden. Sie konzentriert sich auf die Charakteristik der TE-Aktivität und deren Einfluss auf akustische Signale. Die TE-Klassifizierung wird definiert, indem die Beziehung zwischen akustischen und elektrischen Signalen von TE-Ereignissen verwendet wird. Obwohl die Empfindlichkeit der akustischen Sensoren im Laufe der Jahre verbessert wurde, bleibt die Erkennung der akustischen Signale von TE-Aktivität das Hauptproblem bei Komponenten in elektrischen Energiesystemen, hauptsächlich Transformatoren. Fehlende Informationen zur Auswertung von elektrischen TE-Signalen und akustischen Signalen sind neben der mechanischen Dämpfung zwei Hauptnachteile der akustischen Messung. Wegen der mechanischen und elektrischen Mechanismen von Wellen, die während der TE-Aktivitäten erzeugt werden, wird deren Verhalten ausführlicher diskutiert, um ein besseres Verständnis über die elektrischen und akustischen Signale zu erhalten. An verschiedenen Elektrodenkonfigurationen innerhalb einer Probe im Öltank werden TE-Quellen an verschiedenen Elektrodenkonfigurationen wie Spitze-Platte und Elektrodenkugelanordnung innerhalb einer Probe im Tank erzeugt, um verschiedene Arten von TE zu untersuchen. Neben dem mechanischen Verhalten der akustischen Wellen werden auch elektrische Eigenschaften von TE und verschiedene TE-Messtechniken wie elektrisch, UHF und akustisch behandelt. Die Ergebnisse bezüglich des Verhältnisses zwischen AE- und elektrischen TE-Signalen für Korona im Öl zeigen das korrelierte Verhalten zwischen AE- und TE-Signalen. Bei Oberflächenentladungen sind diese Verhaltensweisen jedoch unkorreliert. Die Oberflächenentladung wird genauer untersucht, was zu den ersten Ergebnissen von TE mit sehr geringer akustischer (keine akustischen Signale) Aktivität führt. In Bezug auf diese Ergebnisse werden zwei verschiedene Kategorien in Bezug auf elektrische und AE-Signale von TE definiert, stille TE und nicht-stille TE. Stille TE sind elektrische TE-Signale ohne oder mit sehr geringer akustischer Aktivität, und nicht-stille TE sind elektrische TE-Signale mit akustischer Aktivität. Die Existenz der stillen PD wird über Oszilloskope und digitale Signalverarbeitungsgeräte (DSP) validiert. Auch mit verschiedenen innovativen Methoden und Anordnungen wie Nadel und Kugelelektroden mit und ohne Ölspalt werden die wahrscheinlichen Entstehungsursachen dieses Phänomens (Silent TE) untersucht. Es wurde festgestellt, dass die Karbonisierungsmuster mit nicht-stiller TE beginnen und während stiller TE-Aktivitäten selbst bei sehr hohen scheinbaren elektrischen Ladungen unverändert bleiben. Dies bedeutet, dass bei der Entwicklung der Karbonisierungsspuren elektrische und AE-Signale erzeugt werden und im Gegensatz dazu ohne Änderungen der Karbonisierungsspuren nur elektrische Signale (ohne AE-Signale) erzeugt werden. Diese Differenzierung ist nur möglich bei gleichzeitigem Einsatz der akustischen Technik und elektrischen Messung im Hinblick auf die TE-Klassifizierung und Lokalisierung

An analysis of intestinal morphology and incretin-producing cells using tissue optical clearing and 3-D imaging

Tissue optical clearing permits detailed evaluation of organ three-dimensional (3-D) structure as well as that of individual cells by tissue staining and autofluorescence. In this study, we evaluated intestinal morphology, intestinal epithelial cells (IECs), and enteroendocrine cells, such as incretin-producing cells, in reporter mice by intestinal 3-D imaging. 3-D intestinal imaging of reporter mice using optical tissue clearing enabled us to evaluate both detailed intestinal morphologies and cell numbers, villus length and crypt depth in the same samples. In disease mouse model of lipopolysaccharide (LPS)-injected mice, the results of 3-D imaging using tissue optical clearing in this study was consistent with those of 2-D imaging in previous reports and could added the new data of intestinal morphology. In analysis of incretin-producing cells of reporter mice, we could elucidate the number, the percentage, and the localization of incretin-producing cells in intestine and the difference of those between L cells and K cells. Thus, we established a novel method of intestinal analysis using tissue optical clearing and 3-D imaging. 3-D evaluation of intestine enabled us to clarify not only detailed intestinal morphology but also the precise number and localization of IECs and incretin-producing cells in the same samples