Este trabajo fue apoyado por una BU / CIMIT Beca Predoctoral de Ingeniería Aplicada de Salud, la Fundación Nacional de Ciencia ampliar la participación de Investigación Iniciación Grant en Ingeniería (BRIGE), y los Institutos Nacionales de Salud (R21EB0094930).

1. Preparación de Nanoemulsión Phase-shift (PSNE) <ol><li> Disolver 11 mg de DPPC y 1,68 mg de DSPE-PEG2000 en cloroformo </li><li> Se evapora el disolvente orgánico para formar una película seca de lípido en un vaso matraz de fondo redondo </li><li> Desecar la película lipídica durante la noche </li><li> Rehidratar la película lipídica con 5,5 ml de salina tamponada con fosfato (PBS) </li><li> Solución Calentar en un baño de agua de 45 ° C hasta que se disuelve película lipídica, agitando periódicamente </li><li> Transfiera la solución de lípidos en el vial de 7 ml </li><li> Sonicar solución de lípidos durante 2 min a 20% de la amplitud </li><li> Divida la solución en dos viales de 2,5 ml cada una (descartar restante 0,5 ml) </li><li> Añadir 2,5 ml de PBS a cada vial </li><li> Colocar el vial en un 0 ° C baño de agua helada </li><li> Añadir 50 DDFP l a cada vial </li><li> Sonicar cada vial en el baño de hielo-agua usando la siguiente configuración: 25% de la amplitud, el modo pulsado (10 segundos encendido, apagado 50 seg), 60 seg en total de tiempo </li><li> Transfer PSNE soluciones a viales de centelleo de 20 ml </li><li> Añadir 5 ml de PBS a cada vial, lo que resulta en 10 ml de volumen final, </li><li> Ensamble direcciones extrusora establecidos por el fabricante <ol><li> Enjuague cada parte con agua desionizada </li><li> Coloque el disco de soporte de acero inoxidable en el centro de la base de soporte de filtro </li><li> Coloque la malla de acero inoxidable en la parte superior del disco de soporte de acero inoxidable </li><li> Utilizando pinzas, coloque un drenaje extrusora membrana disco (el lado brillante hacia arriba) en la malla de acero inoxidable </li><li> Usando pinzas, colocar el filtro extrusora (hasta el lado brillante) en la membrana del disco de drenaje </li><li> Coloque con cuidado la pequeña junta tórica en el filtro y coloque la parte superior del extrusor thermobarrel y por encima de la base de apoyo </li><li> Apriete parcialmente cada tuerca de mariposa, luego apriete completamente las tuercas de alas a mano de forma alterna </li><li> Conectar la extrusora auna línea de gas nitrógeno </li><li> Para cebar la extrusora, una pipeta 10 ml de agua desionizada en el puerto de muestreo superior, tapar la abertura y apriete la válvula de ventilación </li><li> Lentamente abrir la línea de gas nitrógeno para aumentar la presión, forzando a la muestra a través de las membranas, y recoger la muestra de la tubería de salida </li><li> Después de su uso, desmonte en orden inverso, enjuague las piezas de extrusión con agua desionizada, y deseche el filtro de membrana y el disco de membrana de drenaje </li></ol></li><li> Por 100 nm sólo gotas, pre-condición PSNE por extrusión de 10 veces a través de 200 nm filtro </li><li> Extrusión PSNE 16 veces a través de 100 nm o 200 nm filtro para obtener la distribución de tamaño estrecha </li></ol> 2. Preparación de hidrogel de poliacrilamida que contiene PSNE <ol><li> Preparar 24% de solución de BSA por dilución de 1,2 g de BSA en polvo en 5 ml de agua desionizada </li><li> Preparar solución al 10% diluida por APS polvo 0,1 g de APS en 1 ml desionizada water </li><li> En el siguiente orden, mezclar 2,1 ml solución de acrilamida, 1,2 ml de tampón Tris, 0,1 ml de APS 10%, 4,5 ml 24% de solución de BSA, y 3,6 ml de agua desionizada en la cámara de plástico </li><li> Calentar a 40 ° C y se coloca bajo vacío durante 1 hr </li><li> Añadir 480 l de PSNE y mezcle girando suavemente la cámara de plástico. </li><li> Añadir 12 l de TEMED y colocar la cámara en un baño de agua 12 ° C durante 2 hr </li></ol> 3. Los resultados representativos Un esquema de la instalación para los experimentos de ultrasonido con fantasmas de hidrogel que imitan el tejido se muestra en la figura 1. Este protocolo da como resultado gotitas de perfluorocarbono lípidos recubiertos con una estrecha distribución de tamaño que son estables en solución durante al menos una semana. La distribución del tamaño medido con dispersión de luz dinámica (partículas 90Plus Analizador de Tamaño, Instrumentos Brookhaven, Holtsville, NY) se muestra en la Figura 2 para PSNE extruyó usando 100 y 200filtros nm. El diámetro PSNE eficaz en el tiempo, medido mediante dispersión dinámica de luz, se enumeran en la Tabla 1, lo que demuestra que PSNE son estables por lo menos durante una semana. Modo B de PSNE antes y después de la vaporización en un hidrogel de poliacrilamida se muestran en la Figura 3. También, una lesión formada por 15 seg de HIFU mediada por calentamiento en un hidrogel de poliacrilamida que contiene albúmina y PSNE se muestra en la Figura 4. La forma asimétrica de la lesión es el resultado de calefacción prefocal que se produce debido a la presencia de la nube de burbujas en la trayectoria de ultrasonido. Es importante tener en cuenta que el calentamiento prefocal y formación de la lesión debido a la dispersión de burbujas puede minimizarse mediante la reducción de la potencia acústica transmitida. <img src="/files/ftp_upload/4308/4308fig1.jpg" alt="Figura 1"/> Figura 1. Esquema del montaje experimental para experimentos con tejido de ultrasonido-mimIcking hidrogeles. <img src="/files/ftp_upload/4308/4308fig2.jpg" alt="Figura 2"/> Figura 2. Distribución de tallas de PSNE extruido a través de 100 nm o 200 nm filtros, medida mediante dispersión de luz dinámica. Las unidades de los ejes de ordenadas se basan en la intensidad de la luz dispersada de partículas de un tamaño determinado con respecto a la intensidad total de la luz dispersada por la muestra. <img src="/files/ftp_upload/4308/4308fig3.jpg" alt="Figura 3"/> Figura 3. Modo B (a) antes y después (b) vaporización PSNE en un hidrogel de poliacrilamida. La flecha indica la región central donde se formó una nube de burbujas por vaporización PSNE. <img src="/files/ftp_upload/4308/4308fig4.jpg" alt="Figura 4"/> Figura 4. Imágenes de polyacrilamida hidrogel que contiene albúmina y PSNE (a) antes y después (b) vaporización y sonicación con HIFU, lo que demuestra la formación de lesiones como resultado de la ecografía inducida por calentamiento. La frecuencia central ultrasonido fue de 3,3 MHz. La señal de ultrasonido inicial consistió en un ciclo de 30-, 6,4 W pulso para vaporizar PSNE, inmediatamente seguido de 15 segundos de ultrasonido continuo a 0,77 W. <table border="1"><tbody><tr><td rowspan="2"> Días después de la extrusión </td><td colspan="2"> Extruido con filtro de 200 nm </td><td colspan="2"> Extruido con 100 nm filtro </td></tr><tr><td> La media de Dia. (Nm) </td><td> Std. Dev. (Nm) </td><td> La media de 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> Tabla 1. El diámetro medio y la desviación estándar de PSNE en uno y siete días después de la extrusión con 100 nm y 200 nm filtros.

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No hay conflictos de interés declarado.

Ultrasonido enfocado de alta intensidad (HIFU) se utiliza clínicamente para ablación térmica de tumores. 1 Para mejorar el calentamiento localizado y mejorar la ablación térmica de tumores, lípidos recubiertos con gotitas de perfluorocarbono se han desarrollado que puede ser vaporizado por HIFU. La vasculatura en muchos tumores es anormalmente permeable debido a su rápido crecimiento. 2 Por lo tanto, las nanopartículas son capaces de penetrar en las fenestraciones y una acumulación pasiva ...

<table border="1"><tbody><tr><td> Nombre común </td><td> Fabricante </td><td> Cat. Número </td><td> Nombre completo / Descripción </td></tr><tr><td> DPPC </td><td> Avanti Lípidos, Alabaster, AL, USA </td><td> 850355P </td><td> 1,2-dipalmitoil-sn-glicero-3-fosfocolina </td></tr><tr><td> DSPE-PEG2000 </td><td> Avanti Lípidos, Alabaster, AL, USA </td><td> 880120P </td><td> 1,2-distearoil-sn-glicero-3-fosfoetanolamina-N-[metoxi (polietilenglicol) -2000] (sal de amonio) </td></tr><tr><td> DDFP </td><td> Fluoromed, Round Rock, TX, EE.UU. </td><td> CAS: 138495-42-8 </td><td> Dodecafluoropentano (C 5 F 12) </td></tr><tr><td> PBS </td><td> Sigma-Aldrich, St Louis, MO, EE.UU. </td><td> P2194 </td><td> Salina tamponada con fosfato </td></tr><tr><td> Cloroformo </td><td> Sigma-Aldrich, St. Louis, MO, EE.UU. </td><td> 372978 </td><td> Cloroformo </td></tr><tr><td> La acrilamida </td><td> Sigma-Aldrich, St Louis, MO, EE.UU. </td><td> A9926 </td><td> 40% 19:1 acrilamida / bis-acrilamida </td></tr><tr><td> Tampón Tris </td><td> Sigma-Aldrich, St Louis, MO, EE.UU. </td><td> T2694 </td><td> 1 M, pH 8, hidrocloruro de Trizma y de base Trizma </td></tr><tr><td> BSA </td><td> Sigma-Aldrich, St Louis, MO, EE.UU. </td><td> A3059 </td><td> Albúmina de suero bovino </td></tr><tr><td> APS </td><td> Sigma-Aldrich, St Louis, MO, EE.UU. </td><td> A3678 </td><td> Solución de persulfato de amonio </td></tr><tr><td> TEMED </td><td> Sigma-Aldrich, St Louis, MO, EE.UU. </td><td> 87689 </td><td> N, N, N &#39;, N&#39;-tetrametiletilendiamina </td></tr><tr><td></td><td></td><td></td><td> Equipo </td></tr><tr><td> Sonicator (3 punta mm) </td&gt; <td> Sonics &amp; Materials, Inc., Newtown, CT, EE.UU. </td><td> Vibra-Cell </td><td></td></tr><tr><td> Baño de agua </td><td> Thermo Fisher Scientific, Waltham, MA, EE.UU. </td><td> Neslab EX-7 </td><td></td></tr><tr><td> Extrusora </td><td> Los lípidos del Norte, Burnaby, BC, Canadá </td><td> LIPEX </td><td></td></tr><tr><td> Extrusora Filtros </td><td> Whatman, Piscataway, NJ, EE.UU. </td><td> Nuclepore # 110605 y # 110606 </td><td></td></tr><tr><td> Extrusora drenaje Disc </td><td> Sterlitech Corporation, Kent, WA, EE.UU. </td><td> # PETEDD25100 </td><td></td></tr><tr><td> Cámara de plástico </td><td> EE.UU. Plastic Corporation, Lima, OH, EE.UU. </td><td> # 55288, 1 3/16 &quot;x 1 3/16&quot; x 2 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

Ultrasonido enfocado de alta intensidad (HIFU) se utiliza clínicamente para seccionan térmicamente los tumores. Para mejorar el calentamiento localizado y mejorar la ablación térmica de tumores, lípidos recubiertos con gotitas de perfluorocarbono se han desarrollado que puede ser vaporizado por HIFU. La vasculatura en muchos tumores es anormalmente permeable debido a su rápido crecimiento, y las nanopartículas son capaces de penetrar las fenestraciones y por pasiva se acumulan en los tumores. Por lo tanto, el control del tamaño de las gotitas puede resultar en una mejor acumulación dentro de los tumores. En este informe, la preparación de gotitas estables en una nanoemulsión de cambio de fase (PSNE) con una distribución de tamaño estrecha se describe. PSNE fueron sintetizados por sonicación de una solución de lípidos en presencia de perfluorocarbono líquido. Una distribución de tamaño estrecha se obtiene por extrusión de las veces PSNE múltiples utilizando filtros con tamaños de poro de 100 o 200 nm. La distribución del tamaño se midió durante un período de 7 días usando dispersión de luz dinámica. Polyachidrogeles que contienen rylamide PSNE se prepararon para los experimentos in vitro. Gotitas PSNE en los hidrogeles se vaporiza con ultrasonido y las burbujas resultantes mejoradas calentamiento localizado. Vaporizado PSNE permite un calentamiento más rápido y también reduce la intensidad de ultrasonido necesario para la ablación térmica. Así, PSNE se espera mejorar la ablación térmica de tumores, potencialmente mejorar los resultados terapéuticos de HIFU mediadas por tratamientos de ablación térmica.

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

Cambio de fase (nanoemulsiones PSNE) puede ser vaporizado mediante ultrasonidos focalizados de alta intensidad para mejorar la calefacción localizada y mejorar la ablación térmica en los tumores. En este informe, la preparación de PSNE estable con una distribución de tamaño estrecha se describe. Además, el impacto de PSNE vaporizado en ablación por ultrasonidos mediada se demuestra en fantasmas que imitan tejidos.

Síntesis de nanoemulsiones de cambio de fase con distribuciones de tamaño estrechas para la vaporización Droplet acústica y Bubble mejorada ablación por ultrasonidos mediada

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

11.0K vistas.  Boston University. Cambio de fase (nanoemulsiones PSNE) puede ser vaporizado mediante ultrasonidos focalizados de alta intensidad para mejorar la calefacción localizada y mejorar la ablación térmica en los tumores. En este informe, la preparación de PSNE estable con una distribución de tamaño estrecha se describe. Además, el impacto de PSNE vaporizado en ablación por ultrasonidos mediada se demuestra en fantasmas que imitan tejidos.

Video: 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.

Controlar el tamaño, forma y estabilidad de los polímeros supramoleculares en el agua

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

Investigación

Ingeniería

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.

Síntesis y funcionamiento de los núcleos fluorescentes microcavidades de Percepción refractométrico

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.

Proceso de fabricación microestructuras tridimensionales mediante vaporización de un componente de sacrificio

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.

Fabricación, operación y visualización del flujo en la superficie-acústico de ondas impulsadas Microfluídica Acústica contraflujo

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.

Caracterización de Nanocristal distribución por tamaño utilizando espectroscopia Raman con un multi-partícula Phonon Confinamiento Modelo

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).

Caracterización del conjunto completo constantes del material y su dependencia de la temperatura de los materiales piezoeléctricos El uso de ultrasonido Espectroscopía de Resonancia

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.

Dispositivo de microfluidos centrífuga basada en capilar para la Formación Tamaño-controlable de monodisperso microgotas

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.

Fabricación y funcionamiento de los dispositivos de apoyo a granel Acoustofluidic ondas acústicas pie para Sheathless Centrándose de partículas

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.

Medir el tamaño de pulverización de gota de boquillas agrícolas Uso de difracción láser

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.

Método basado en una punta de pipeta para siembra células gota microfluídicos plataformas

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