Diese Arbeit wurde von einer BU / CIMIT Applied Healthcare Engineering-Promotionsstipendium, ein National Science Foundation eine stärkere Beteiligung Forschung Initiation Grant in Engineering (BRIGE) und den National Institutes of Health (R21EB0094930) unterstützt.

Ein. Vorbereitung der Phase-Shift-Nanoemulsion (PSNE) <ol><li> Lösen Sie 11 mg DPPC und 1,68 mg DSPE-PEG2000 in Chloroform </li><li> Verdunstet das organische Lösungsmittel, um eine trockene Lipidfilm in einem Glas-Rundkolben bilden </li><li> Auszutrocknen den Lipidfilm Nacht </li><li> Rehydrieren des Lipidfilms mit 5,5 ml phosphatgepufferter Kochsalzlösung (PBS) </li><li> Wärme-Lösung in einem 45 ° C Wasserbad, bis Lipidfilm auflöst, Vortexen periodisch </li><li> Übertragen Lipid-Lösung in 7 ml Flasche </li><li> Beschallen Lipidlösung während 2 min bei 20% Stauchung </li><li> Dividieren Lösung in zwei Fläschchen 2,5 ml (verwerfen verbleibenden 0,5 ml) </li><li> 2,5 ml PBS in jede Phiole </li><li> Platzieren Sie jede Flasche in einer 0 ° C Eis-Wasser-Bad </li><li> Fügen Sie 50 ul DDFP in jedes Fläschchen </li><li> Beschallen jedes Fläschchen im Eis-Wasser-Bad mit den folgenden Einstellungen: 25% Amplitude, gepulsten Modus (10 sec ein, 50 s aus), 60 sec insgesamt auf Zeit </li><li> Transfer PSNE Lösungen für 20 ml Szintillationsgefäße </li><li> 5 ml PBS in jedes Fläschchen, was in 10 ml Endvolumen </li><li> Montieren Extruder folgenden Richtungen vom Hersteller bereitgestellten <ol><li> Spülen Sie jedes Teil mit VE-Wasser </li><li> Das Edelstahlblech Stützscheibe in der Mitte des Filters Trägerbasis </li><li> Legen Sie das Edelstahlgewebe auf der Edelstahl-Stützscheibe </li><li> Mit einer Pinzette, legen einen Extruder Abfluss Disc Membran (glänzende Seite nach oben) auf dem Edelstahlgewebe </li><li> Mit einer Pinzette, platzieren Sie den Extruder Filter (glänzende Seite nach oben) auf den Drain-Disc-Membran </li><li> Legen Sie das kleine O-Ring auf dem Filter und platzieren Sie den thermobarrel und Extruder oben über der Trägerbasis </li><li> Teilweise ziehen jedes Flügelmutter, dann ganz fest die Flügelmuttern von Hand abwechselnd </li><li> Verbinden Sie den Extrudereine Stickstoff-Gasleitung </li><li> Um den Extruder, Pipette 10 ml deionisiertem Wasser in den oberen Probeöffnung grundieren, verschließen Sie die Öffnung, und ziehen Sie das Entlüftungsventil </li><li> Langsam das Stickstoffgas Zeile, um den Druck zu erhöhen, wodurch der Probe durch die Membranen, und sammeln der Probe aus dem Auslassschlauch </li><li> Nach dem Gebrauch, in umgekehrter Reihenfolge zu zerlegen, spülen Sie die Extruder Teile mit VE-Wasser, und entsorgen Sie die Membran und Membran-Drain Disc </li></ol></li><li> Für 100 nm Tröpfchen nur Voraussetzung PSNE durch Extrudieren 10 mal durch 200-nm-Filter </li><li> Extrude PSNE 16 mal durch 100 nm oder 200 nm Filter engen Größenverteilung zu erhalten </li></ol> 2. Vorbereitung der Polyacrylamid Hydrogel PSNE <ol><li> Bereiten Sie 24% BSA-Lösung durch Verdünnen 1,2 g BSA-Pulver in 5 ml deionisiertem Wasser </li><li> Bereiten Sie 10% APS-Lösung mit verdünnter 0,1 g APS Pulver in 1 ml deionisiertem water </li><li> In der folgenden Reihenfolge, mischen 2,1 ml Acrylamid-Lösung, 1,2 ml Tris-Puffer, 0,1 ml 10% APS, 4,5 ml 24% BSA-Lösung und 3,6 ml deionisiertem Wasser in Kunststoffkammer </li><li> Wärme auf 40 ° C und unter Vakuum für 1 Stunde </li><li> Fügen Sie 480 ul PSNE und gründlich durch vorsichtiges Schwenken der Kunststoff-Kammer mischen. </li><li> Fügen Sie 12 ul TEMED und legen Sie die Kammer in einem 12 ° C Wasserbad für 2 Stunden </li></ol> 3. Repräsentative Ergebnisse Eine schematische Darstellung der Einrichtung zur Ultraschall-Experimenten mit Gewebe-Nachahmung Hydrogel Phantome ist in Abbildung 1 gezeigt. Dieses Protokoll ergibt lipidbeschichteten Perfluorkohlenstoff Tröpfchen mit einer engen Größenverteilung, die stabil in Lösung sind für mindestens eine Woche. Die Größenverteilung mit dynamischer Lichtstreuung (90Plus Particle Size Analyzer, Brookhaven Instruments, Holtsville, NY) gemessen wird in Abbildung 2 PSNE extrudiert mit 100 und 200 gezeigtnm Filtern. Der effektive Durchmesser PSNE über die Zeit, gemessen mittels dynamischer Lichtstreuung, ist in Tabelle 1 aufgeführt, die zeigen, dass PSNE stabil sind für mindestens eine Woche. B-Modus-Bilder vor und nach PSNE Verdampfung in einem Polyacrylamid-Hydrogel, sind in Abbildung 3 dargestellt. Auch kann eine Läsion von 15 sec. der HIFU-vermittelte Erhitzen in einem Polyacrylamid-Hydrogel enthaltend Albumin und PSNE ist in Abbildung 4 dargestellt ist. Die asymmetrische Form der Läsion ist ein Ergebnis der prefocal Heizung, die aufgrund des Vorhandenseins der Blase Wolke im Ultraschallstrecke auftritt. Es ist wichtig, dass die Heiz-und prefocal Läsionsbildung aufgrund Streuung von Blasen beachten kann durch Reduktion der übertragenen akustischen Energie minimiert werden. <img src="/files/ftp_upload/4308/4308fig1.jpg" alt="Abbildung 1"/> Abbildung 1. Schematische Darstellung des experimentellen Aufbaus für die Ultraschall-Experimenten mit Gewebe-mimIcking Hydrogele. <img src="/files/ftp_upload/4308/4308fig2.jpg" alt="Abbildung 2"/> Abbildung 2. Größe Verteilung der PSNE extrudiert durch 100 nm oder 200 nm Filter, gemessen mittels dynamischer Lichtstreuung. Die Einheiten der Ordinate Achsen auf der Intensität des gestreuten Lichts von Teilchen einer bestimmten Größe in Bezug auf das Gesamtgewicht Streulichtintensität aus der Probe. <img src="/files/ftp_upload/4308/4308fig3.jpg" alt="Abbildung 3"/> Abbildung 3. B-Modus-Bilder (a) vor und (b) nach PSNE Verdampfung in einem Polyacrylamid-Hydrogel. Der Pfeil zeigt die Fokalbereich wo eine Blase Wolke von PSNE Verdampfung gebildet wurde. <img src="/files/ftp_upload/4308/4308fig4.jpg" alt="Abbildung 4"/> Abbildung 4. Bilder polyacrylamid Hydrogel enthaltend Albumin und PSNE (a) vor und (b) nach Verdampfung und Beschallung mit HIFU, demonstriert Läsionsbildung als Folge von Ultraschall-induzierten Erwärmung. Die Ultraschall-Mittenfrequenz bei 3,3 MHz. Das Ultraschallsignal bestand aus einem ersten 30-Zyklus, 6,4 W Impuls PSNE verdampfen sofort 15 sec von kontinuierlichem Ultraschall bei 0,77, gefolgt W. <table border="1"><tbody><tr><td rowspan="2"> Tage nach der Extrusion </td><td colspan="2"> Extrudierte mit 200-nm-Filter </td><td colspan="2"> Extrudierte mit 100 nm-Filter </td></tr><tr><td> Mittlere Dia. (Nm) </td><td> Std. Dev. (Nm) </td><td> Mittlere Dia. (Nm) </td><td> Std. Dev. (Nm) </td></tr><tr><td> 1 </td><td> 182,9 </td><td> 4,9 </td><td> 118,0 </td><td> 0,9 </td></tr><tr><td> 7 </td> &lt;td&gt; 177,7 </td><td> 2,5 </td><td> 124,8 </td><td> 3,1 </td></tr></tbody></table> Tabelle 1. Mittlerer Durchmesser und die Standardabweichung der PSNE an einem und sieben Tage nach der Extrusion mit 100 nm und 200 nm Filter.

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High-Intensity Focused Ultrasound (HIFU) ist klinisch zur thermischen Ablation von Tumoren eingesetzt. 1 Um lokale Erwärmung und zur Verbesserung thermischen Ablation in Tumoren haben lipidbeschichteten Perfluorcarbon Tröpfchen entwickelt worden, die durch die HIFU verdampft werden. Das Gefäßsystem in vielen Tumoren außergewöhnlich leaky durch ihr rasches Wachstum. 2 somit in der Lage, die Nanopartikel Fenestrationen eindringen und passiv in Tumoren anreichernden, ein Vorgang, der erhöhte Pe...

<table border="1"><tbody><tr><td> Common Name </td><td> Hersteller </td><td> Cat. Anzahl </td><td> Vollständiger Name / Beschreibung </td></tr><tr><td> DPPC </td><td> Avanti Lipids, Alabaster, AL, USA </td><td> 850355P </td><td> 1,2-Dipalmitoyl-sn-glycero-3-phosphocholin </td></tr><tr><td> DSPE-PEG2000 </td><td> Avanti Lipids, Alabaster, AL, USA </td><td> 880120P </td><td> 1,2-Distearoyl-sn-glycero-3-phosphoethanolamin-N-[methoxy (polyethylenglykol) -2000] (Ammoniumsalz) </td></tr><tr><td> DDFP </td><td> Fluoromed, Round Rock, TX, USA </td><td> CAS: 138495-42-8 </td><td> Dodecafluorpentan (C 5 F 12) </td></tr><tr><td> PBS </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> P2194 </td><td> Phosphat-gepufferte Kochsalzlösung </td></tr><tr><td> Chloroform </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> 372978 </td><td> Chloroform </td></tr><tr><td> Acrylamid </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> A9926 </td><td> 40% 19.01 Acrylamid / Bisacrylamid </td></tr><tr><td> Trispuffer </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> T2694 </td><td> 1M, pH 8, Trizma-Hydrochlorid und Trizma-Base </td></tr><tr><td> BSA </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> A3059 </td><td> Rinderserumalbumin </td></tr><tr><td> APS </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> A3678 </td><td> Ammoniumpersulfatlösung </td></tr><tr><td> TEMED </td><td> Sigma-Aldrich, St. Louis, MO, USA </td><td> 87689 </td><td> N, N, N &#39;, N&#39;-Tetramethylethylendiamin </td></tr><tr><td></td><td></td><td></td><td> Ausrüstung </td></tr><tr><td> Sonicator (3 mm Spitze) </td&gt; <td> Sonics &amp; Materials, Inc., Newtown, CT, USA </td><td> Vibra-Cell </td><td></td></tr><tr><td> Wasserbad </td><td> Thermo Fisher Scientific, Waltham, MA, USA </td><td> Neslab EX-7 </td><td></td></tr><tr><td> Extruder </td><td> Northern Lipids, Burnaby, BC, Kanada </td><td> LIPEX </td><td></td></tr><tr><td> Extruder Filter </td><td> Whatman, Piscataway, NJ, USA </td><td> Nuclepore # 110605 und # 110606 </td><td></td></tr><tr><td> Extruder Abfluss Disc </td><td> Sterlitech Corporation, Kent, WA, USA </td><td> # PETEDD25100 </td><td></td></tr><tr><td> Kunststoffkammer </td><td> US Plastic Corporation, Lima, OH, USA </td><td> # 55288, 1 3/16 &quot;x1 3/16&quot; x2 7/16 &quot; </td><td></td></tr></tbody></table>

synthesis of phase-shift nanoemulsions with narrow size distributions for acoustic droplet vaporization and bubble-enhanced ultrasound-mediated ablation

High-Intensity Focused Ultrasound (HIFU) wird klinisch zur thermischen Ablation von Tumoren eingesetzt. Um örtliche Erwärmung und zur Verbesserung thermischen Ablation in Tumoren haben lipidbeschichteten Perfluorkohlenstoff Tröpfchen entwickelt worden, die durch HIFU verdampft werden. Das Gefäßsystem in vielen Tumoren außergewöhnlich leaky durch ihr rasches Wachstum und Nanopartikeln Lage sind, die Fensteranordnungen eindringen und passiv in Tumoren anreichern. Somit kann die Steuerung der Größe der Tröpfchen in bessere Anreicherung in Tumoren führen. In diesem Bericht wird die Herstellung von stabilen Tröpfchen in einer Phase-Shift-Nanoemulsion (PSNE) mit einer engen Größenverteilung beschrieben. PSNE wurden im Ultraschallbad eine Lipidlösung in Gegenwart des flüssigen Perfluorkohlenstoff synthetisiert. Eine enge Größenverteilung wurde durch Extrudieren der PSNE mehrfach die Verwendung von Filtern mit einer Porengröße von 100 bzw. 200 nm erhalten. Die Größenverteilung wurde über einen 7-Tages-Frist mittels dynamischer Lichtstreuung gemessen. Polyacrylamide Hydrogele mit PSNE wurden in vitro Experimente vorbereitet. PSNE Tröpfchen in der Hydrogele wurden mit Ultraschall und die resultierenden Blasen verbessert lokalisierte Erwärmung verdampft. Verdampften PSNE ermöglicht schnelleres Aufheizen und verringert auch die Ultraschallintensität zur thermischen Ablation benötigt. So wird PSNE erwartet thermischen Ablation von Tumoren zu verbessern, potentiell verbessert therapeutischen Ergebnisse der HIFU-vermittelte thermischen Ablation Behandlungen.

Watch this Scientific Journal Video about Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation at Jo

Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

Phase-shift Nanoemulsionen (PSNE) kann verdampft mit hoher Intensität fokussierter Ultraschall, um lokale Erwärmung und zur Verbesserung thermischen Ablation von Tumoren sein. In diesem Bericht wird die Herstellung von stabilen PSNE mit einer engen Größenverteilung beschrieben. Darüber hinaus wird der Einfluss des verdampften PSNE auf Ultraschall-vermittelte Ablation im Gewebe-ähnlichen Phantomen demonstriert.

Synthese von Phase-shift Nanoemulsionen mit enger Größenverteilung für Acoustic Droplet Vaporisation und Bubble-enhanced Ultraschall-vermittelte Ablation

High-intensity  focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To  enhance localized heating and improve thermal ablation in ...

synthesis-phase-shift-nanoemulsions-with-narrow-size-distributions

Research

JoVE Journal

Engineering

10.9K Aufrufe.  Boston University. Phase-shift Nanoemulsionen (PSNE) kann verdampft mit hoher Intensität fokussierter Ultraschall, um lokale Erwärmung und zur Verbesserung thermischen Ablation von Tumoren sein. In diesem Bericht wird die Herstellung von stabilen PSNE mit einer engen Größenverteilung beschrieben. Darüber hinaus wird der Einfluss des verdampften PSNE auf Ultraschall-vermittelte Ablation im Gewebe-ähnlichen Phantomen demonstriert.

Serie: Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

Steuern der Größe, Form und Stabilität der supramolekularen Polymeren in Wasser

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

Forschung

Ingenieurwesen

Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing

This paper discusses fluorescent core microcavity-based sensors that can operate in a microfluidic analysis setup. These structures are based on the formation of a fluorescent quantum-dot (QD) coating on the channel surface of a conventional microcapillary. Silicon QDs are especially attractive for this application, owing in part to their negligible toxicity compared to the II-VI and II-VI compound QDs, which are legislatively controlled substances in many countries. While the ensemble emission spectrum is broad and featureless, an Si-QD film on the channel wall of a capillary features a set of sharp, narrow peaks in the fluorescence spectrum, corresponding to the electromagnetic resonances for light trapped within the film. The peak wavelength of these resonances is sensitive to the external medium, thus permitting the device to function as a refractometric sensor in which the QDs never come into physical contact with the analyte. The experimental methods associated with the fabrication of the fluorescent-core microcapillaries are discussed in detail, as well as the analysis methods. Finally, a comparison is made between these structures and the more widely investigated liquid-core optical ring resonators, in terms of microfluidic sensing capabilities.

Fluorescent-core microcavity sensors employ a high-index quantum-dot coating in the channel of silica microcapillaries. Changes in the refractive index of fluids pumped into the capillary channel cause shifts in the microcavity fluorescence spectrum that can be used to analyze the channel medium.

Synthese und Betrieb von Leuchtstofflampen-core Mikrokavitäten für Refraktometrische Sensing

This paper discusses  fluorescent core microcavity-based sensors that can operate in a microfluidic  analysis setup. These structures are based on the ...

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

Verfahren zur Herstellung von dreidimensionalen Mikrostrukturen mit Verdampfung eines Opferbauteil

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.

In this video we first describe fabrication and operation procedures of a surface acoustic wave (SAW) acoustic counterflow device. We then demonstrate an experimental setup that allows for both qualitative flow visualization and quantitative analysis of complex flows within the SAW pumping device.

Fabrication, Operation and Flow Visualization in Oberflächenschallwellen-wave-driven Acoustic-Gegenstrom Mikrofluidik

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

Charakterisierung von Nanokristallgrößenverteilung mittels Raman-Spektroskopie mit einem Multi-Partikel Phonon Confinement Modell

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

Characterization of Full Set Material Constants and Their Temperature Dependence for Piezoelectric Materials Using Resonant Ultrasound Spectroscopy

During the operation of high power electromechanical devices, a temperature rise is unavoidable due to mechanical and electrical losses, causing the degradation of device performance. In order to evaluate such degradations using computer simulations, full matrix material properties at elevated temperatures are needed as inputs. It is extremely difficult to measure such data for ferroelectric materials due to their strong anisotropic nature and property variation among samples of different geometries. Because the degree of depolarization is boundary condition dependent, data obtained by the IEEE (Institute of Electrical and Electronics Engineers) impedance resonance technique, which requires several samples with drastically different geometries, usually lack self-consistency. The resonant ultrasound spectroscopy (RUS) technique allows the full set material constants to be measured using only one sample, which can eliminate errors caused by sample to sample variation. A detailed RUS procedure is demonstrated here using a lead zirconate titanate (PZT-4) piezoceramic sample. In the example, the complete set of material constants was measured from room temperature to 120 &#176;C. Measured free dielectric constants <img alt="Equation 1" src="/files/ftp_upload/53461/image001.jpg" /> and&#160;<img alt="Equation 2" src="/files/ftp_upload/53461/image002.jpg" /> were compared with calculated ones based on the measured full set data, and piezoelectric constants d15 and d33 were also calculated using different formulas. Excellent agreement was found in the entire range of temperatures, which confirmed the self-consistency of the data set obtained by the RUS.

This protocol describes the procedure of measuring the temperature dependence of the full set material constants of piezoelectric materials using resonant ultrasound spectroscopy (RUS).

Charakterisierung von Full Set Materialkonstanten und deren Temperaturabhängigkeit für piezoelektrische Materialien mit Resonanzultraschallspektroskopie

During the operation of high power electromechanical devices, a temperature rise is unavoidable due to mechanical and electrical losses, causing the ...

Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal microfluidic device. W/O microdroplets have recently been used in powerful methods that enable miniaturized chemical experiments. Therefore, developing a versatile method to yield monodisperse W/O microdroplets is needed. We have developed a method for generating monodisperse W/O microdroplets based on a capillary-based centrifugal axisymmetric co-flowing microfluidic device. We succeeded in controlling the size of microdroplets by adjusting the capillary orifice. Our method requires equipment that is easier-to-use than with other microfluidic techniques, requires only a small volume (0.1-1 &#181;l) of sample solution for encapsulation, and enables the production of hundreds of thousands number of W/O microdroplets per second. We expect this method will assist biological studies that require precious biological samples by conserving the volume of the samples for rapid quantitative analysis biochemical and biological studies.

Here, we demonstrate a simple production method for size-controllable, monodisperse, water-in-oil (W/O) microdroplets using a capillary-based centrifugal microfluidic device. This method requires only a small sample volume and enables high-yield production. We expect this method will be useful for rapid biochemical and cellular analyses.

Kapillar-basierten Kreisel Mikrofluidik-Vorrichtung zur Größe steuerbare Bildung von monodispersen Mikrotröpfchen

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.

Acoustofluidic devices use ultrasonic waves within microfluidic channels to manipulate, concentrate and isolate suspended micro and nanoscopic entities. This protocol describes the fabrication and operation of such a device supporting bulk acoustic standing waves to focus particles in a central streamline without the aid of sheath fluids.

Herstellung und Betrieb von Acoustofluidic Devices Unterstützung Bulk-Acoustic-Standing Waves für sheathless Fokussierung der Partikel

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

When making an application of any crop protection material such as an herbicide or pesticide, the applicator uses a variety of skills and information to make an application so that the material reaches the target site (i.e., plant). Information critical in this process is the droplet size that a particular spray nozzle, spray pressure, and spray solution combination generates, as droplet size greatly influences product efficacy and how the spray moves through the environment. Researchers and product manufacturers commonly use laser diffraction equipment to measure the spray droplet size in laboratory wind tunnels. The work presented here describes methods used in making spray droplet size measurements with laser diffraction equipment for both ground and aerial application scenarios that can be used to ensure inter- and intra-laboratory precision while minimizing sampling bias associated with laser diffraction systems. Maintaining critical measurement distances and concurrent airflow throughout the testing process is key to this precision. Real time data quality analysis is also critical to preventing excess variation in the data or extraneous inclusion of erroneous data. Some limitations of this method include atypical spray nozzles, spray solutions or application conditions that result in spray streams that do not fully atomize within the measurement distances discussed. Successful adaption of this method can provide a highly efficient method for evaluation of the performance of agrochemical spray application nozzles under a variety of operational settings. Also discussed are potential experimental design considerations that can be included to enhance functionality of the data collected.

We present protocols to be used in the measurement of spray droplet size from agricultural nozzles used in both aerial and ground based agrochemical applications. These methods presented were developed to provide consistent and repeatable droplet size data both inter- and intra-laboratory, when using laser diffraction systems.

Mess Spray Tröpfchengröße von landwirtschaftlichen Düsen mit Laserbeugung

When making an application of any crop protection material such as an herbicide or pesticide, the applicator uses a variety of skills and information to ...

A Pipette-Tip Based Method for Seeding Cells to Droplet Microfluidic Platforms

Amongst various microfluidic platform designs frequently used for cellular analysis, droplet-microfluidics provides a robust tool for isolating and analyzing cells at the single-cell level by eliminating the influence of external factors on the cellular microenvironment. Encapsulation of cells in droplets is dictated by the Poisson distribution as a function of the number of cells present in each droplet and the average number of cells per volume of droplet. Primary cells, especially immune cells, or clinical specimens can be scarce and loss-less encapsulation of cells remains challenging. In this paper, we present a new methodology that uses pipette-tips to load cells to droplet-based microfluidic devices without the significant loss of cells. With various cell types , we demonstrate efficient cell encapsulation in droplets that closely corresponds to the encapsulation efficiency predicted by the Poisson distribution. Our method ensures loss-less loading of cells to microfluidic platforms and can be easily adapted for downstream single cell analysis, e.g., to decode cellular interactions between different cell types.

This article presents a protocol for seeding scarce population of cells using pipette-tips to droplet microfluidic devices in order to provide higher encapsulation efficiency of cells in droplets.

Eine Pipettenspitze basierte Methode für das Seeding Zellen Tröpfchen mikrofluidischen Plattformen

Amongst various microfluidic platform designs frequently used for cellular analysis, droplet-microfluidics provides a robust tool for isolating and ...