Os autores agradecem o apoio da National Science Foundation, CBET0846359, monitor de concessão Horst Henning inverno.

1. Crie um fluxo mensurável <ol><li> Medições de validação EPIV será demonstrado no fluxo do tubo de uma solução aquosa de glicerina (glicerina a 50% - 50% de água). Um esquema da montagem experimental é apresentado na Figura 1. </li><li> Esferas de vidro ocas com um diâmetro nominal de 10 um são adicionados ao líquido com uma concentração de cerca de 17 partes em peso por milhão. As esferas de vidro ocas servem como agentes de contraste de ultra-sons, e o seu tamanho e densidade são escolhidos de tal forma que eles seguem passivamente o fluxo de fluido 10. </li><li> A tensão fixa é fornecida à bomba para introduzir um caudal conhecido. A taxa de fluxo é escolhido tal que U &lt;&lt; AX / AT, onde U é a velocidade média no tubo, AX é o comprimento linear do volume de medição EPIV, e AT é o intervalo de tempo entre as imagens, isto é, o fluxo necessário &quot;lento&quot; em comparação com o fps do ultra-som syhaste 3. </li></ol> 2. Calibrar o ultra-som <ol><li> Monte a sonda de ultra-som para o tubo de parede exterior. A base de água gel tópica é aplicada à sonda de ultra-sons para reduzir a perda de transmissão do feixe de ultra-som, entre a face da sonda e da parede do tubo. </li><li> De alimentação da máquina de ultra-som. A transmissão ao vivo de imagens de ultra-som começa automaticamente uma vez que toda a carga de sistemas. </li><li> Defina a profundidade da imagem com o botão Controlo de profundidade no painel de controle da máquina de ultra-som. </li><li> Ajuste o ganho total da imagem com o botão Gain 2D no painel de controle da máquina de ultra-som. </li><li> Ajuste o tempo ganho de compensação (TGC) controles deslizantes para atenuar dispersão das paredes da tubulação e para compensar a atenuação relacionada profundidade do sinal de ultra-som. </li><li> A largura da imagem, foco, freqüência de operação da sonda, e taxa de quadros são ajustados usando os botões de controle configuráveis. Estesquatro botões, localizado no canto superior esquerdo do painel de controlo, variam de acordo com o modo em que o sistema está a funcionar. No modo 2D (como utilizado atualmente), a partir da esquerda para a direita os botões correspondem a largura, o foco, freqüência e taxa de quadros, respectivamente. Note-se que, devido aos princípios fundamentais de ultra-som 9, estes quatro parâmetros são inerentemente acopladas. Consequentemente, para uma dada varredura do ultra-som de imagem (isto é, um experimento EPIV) existe uma compensação entre a resolução espacial e temporal. </li><li> Ver Figura 2 para uma imagem de ultra-som de fluxo representativo do tubo semeado com 10 um de esferas de vidro ocas. Note-se que, devido à limitada resolução lateral, as esferas de vidro são manchadas na direcção lateral e aparecem como elipsóides na imagem. </li></ol> 3. Coleta de Dados <ol><li> Pressione o botão Exame Nova no painel de controle de ultra-som para começar uma nova experiência. </li><li> Crie uma&quot;paciente&quot; novo entrando Fluxo de tubulação em Sobrenome e data de hoje, em Nome e o número de teste de ID do paciente. </li><li> Após a criação do &quot;paciente&quot;, uma ecografia começa até o máximo pré-estabelecido entre 1000-1500 imagens é atingido, após o que um laço de digitalização novo começa. Pressionando o botão Freeze no painel de controle de ultra-som duas vezes irá reiniciar a verificação a qualquer momento antes de atingir o número máximo pré-estabelecido de imagens. </li><li> Uma vez que um bom conjunto de imagens de ultra-som foi adquirido (ou seja, imagens nítidas de sementes de partículas e densidade de partículas suficiente de sementes), pressione o botão Freeze no painel de controle de ultra-som para parar de aquisição de imagem. </li><li> Pressione o botão Cineloop no painel de controle de ultra-som. Selecione o conjunto de imagens de ultra-som a ser analisado com o botão Primeiro Ciclo no painel de controle de ultra-som para selecionar a primeira imagem do conjunto, eo botão do último ciclo para selecionar oúltima imagem do conjunto. </li><li> Pressione o botão Image Store no painel de controle de ultra-som para salvar o conjunto selecionado de imagens de ultra-som. </li><li> Pressione o botão Arquivo no painel de controle de ultra-som e usar o cursor do mouse para selecionar Exame Final. Isso fará com que o usuário selecione as imagens ou cineloops para salvar o disco rígido local. Selecione o cineloop (s) de interesse, em seguida, sair do exame. </li><li> Pressione o botão Arquivo no painel de controle de ultra-som e usar o cursor do mouse para selecionar primeiro Mais e, em seguida, selecione Gerenciamento de disco. Gerenciamento de disco irá transferir o cineloop salvo (s) para o PC rodando o software PIV. </li></ol> 4. Convertendo Filetype <ol><li> Uma imagem de ultra-som é armazenado como uma comunicação de imagem digital em medicina (DICOM) tipo de arquivo na máquina de ultra-som. De forma a ser aberta e lida pelo software PIV, os arquivos DICOM devem ser convertidos para ficheiros de imagens. Atualmente,DICOM2JPG.m um script de Matlab execução é usado para converter os arquivos DICOM a junta especialistas tipo de grupo de fotografia de arquivo (JPEG). </li><li> As imagens de ultra-som JPEG são então analisados ​​usando software de LaVision Davis. </li></ol> 5. Computando Campos de deslocamento, D (x, y), usando Davis <ol><li> Do mouse clique duas vezes sobre o ícone Davis no PC. Selecione New Project. Selecione PIV. </li><li> Selecione Importar imagens na barra de ferramentas, e escolha Importar via arquivos numerados. No menu suspenso, localize a pasta onde as imagens de ultra-som JPEG são armazenados, e clique duas vezes na primeira imagem do set. Isto irá importar todas as imagens de ultra-som neste conjunto numerado. </li><li> Tipicamente, uma máscara de imagem será definido para isolar a região de interesse (ROI) na imagem de ultra-som a serem processados. Para o fluxo de tubo, a máscara é utilizada para definir o ROI entre as paredes de tubo (isto é, o fluido). </li><li> Vá para o painel de controle principal em Davis, selecione a aba localizada sob projeto atual que contém as imagens importadas, e selecione a guia processamento em lote rotulados. Isso permite que a janela de processamento vetorial de Davis para processamento em lote das imagens de ultra-som importados. </li><li> A partir da lista de operações, usando a árvore PIV-Time-Series, selecionar os parâmetros de cálculo do vetor, e escolher os parâmetros a serem utilizados para o processamento vetorial. Se uma máscara é usada, verifique a caixa Intervalo de dados = utilizar a área mascarada no menu vetor de parâmetros de cálculo. Observe que a seleção ideal de parâmetros de cálculo vetor é dependente da geometria de fluxo, propriedades de fluxo, resolução de imagem, densidade de partículas traçador, e análise de fluxo desejado quantitativa. 10 Para as medições de fluxo de tubulação, os parâmetros que têm tipicamente produziram os melhores resultados são multipass com tamanho decrescente de interrogação de 32 x 32 pixels x 2-88 pixel 2, com uma sobreposição de 50%. Restrição de faixa relativa vetor foi definida para ± tudo (tamanho da janela / 2) e restrição de faixa absoluta vetor foi definida para ± 5 pixels. Por último, um 3 x 2 3pixel filtro mediana foi utilizada para suprimir o ruído e alisar os campos de vetores. </li><li> No lado esquerdo do ecrã de processamento em lote, seleccione a quantidade total de imagens a ser processadas e seleccionar o processamento inicial. Isto irá calcular o campo de deslocamento, D (x, y), entre as imagens de ultra-som sucessivos usando algoritmos de correlação cruzada. </li></ol> 6. Analisando campos vetoriais <ol><li> Para a análise pós-processamento e dados, os campos de vetores EPIV são exportados como arquivos de Davis. Txt. Isto é conseguido através da selecção do ramo de deslocamento do vetor no ramo de imagem JPEG na tela do projeto. Na barra de ferramentas, selecione a guia de exportação, selecione tipo de arquivo ASCII. Txt, escolher / criar uma pasta de exportação, umad Exportação de seleção. </li><li> Os campos de vetores exportados são nomeados Bxxxxx.txt, onde 00.001 xxxxx ≤ ≤ 99999, com B tampão denotando. Cada arquivo contém quatro colunas de dados: (1) x-localização do vector na imagem, (2) y-localização do vector na imagem (3), x-componente de deslocamento (isto é, o deslocamento streamwise), (4) y-componente de deslocamento (isto é, a parede do normal de deslocamento). Os ficheiros são abertos Bxxxxx.txt e processadas em MATLAB para calcular primeiro o campo de velocidade, sabendo o intervalo de tempo entre pares de imagens, AT [s] e ampliação da imagem, M [m / pixel], ou seja, u (x, y ) = MD (x, y) / AT,. O passo de tempo entre as imagens AT = 1/fps + D (x, y) / B, em que B [pixels / s] é o tempo que leva para que a sonda de ultra-som para varrer toda a largura da imagem. No presente estudo, M = 77 [um / pixel], fps = 49,5 [1 / s], e B = [25047 pixels / s]. Em seguida, ensemveis médios campos de velocidade de vetor, parede normais perfis de velocidade média, entre quantidades de fluxo de interesse são computados. (Veja Resultados representativos de seção.) </li></ol>

<ol>
	<li>White, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fluid Mechanics. , (1994).</li><li>Hak, M. G. a. d. -. e. l. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Flow Control: Passive, Active, and Reactive Flow Management. , (2000).</li><li>Kim, B. H., Hertzberg, J. R., Shandas, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+validation+of+echo+PIV.">Development and validation of echo PIV.</a> Exp. Fluids. 36, 455-462 (2004).</li><li>Zheng, H., Liu, L., Williams, L., Hertzberg, J. R., Lanning, C., Shandas, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real+time+multicomponent+echo+particle+image+velocimetry+technique+for+opaque+flow+imaging.">Real time multicomponent echo particle image velocimetry technique for opaque flow imaging.</a> Appl. Phys. Lett. 88, 261915 (2006).</li><li>Beulen, B., Bijnens, N., Rutten, M., Brands, P., van de Vosse, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perpendicular+ultrasound+velocity+measurement+by+2D+cross+correlation+of+RF+data.+Part+A:+validation+in+a+straight+tube.">Perpendicular ultrasound velocity measurement by 2D cross correlation of RF data. Part A: validation in a straight tube.</a> Exp. Fluids. 49, 1177-1186 (2010).</li><li>Poelma, C., Mari, J. M., Foin, N., Tang, M. -. X., Krams, R., Caro, C. G., Weinberg, P. D., Westerweel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+Flow+reconstruction+using+ultrasound+PIV.">3D Flow reconstruction using ultrasound PIV.</a> Exp. Fluids. 50, 777-785 (2011).</li><li>GE VINGMED ULTRASOUND A/A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Vivid 7/Vivid 7 PRO Userâ€™s Manual. , (1988).</li><li>Szabo, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Diagnostic Ultrasound Imaging: Inside Out. , (2004).</li><li>Raffel, M., Willert, C., Wereley, S., Kompenhans, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Particle Image Velocimetry: A Practical Guide. , (2007).</li></ol>

Autores têm nada a revelar.

O protocolo de funcionamento para um sistema de eco de partícula imagem velocimetria (EPIV) capaz de adquirir bidimensionais campos de velocidade em fluidos opacos opticamente ou através de geometrias opticamente opacas foi descrito. A aplicação prática da EPIV é bem apropriado para o estudo dos sistemas industriais de fluxo e biológico, em que o fluxo de fluidos opacos ocorre em uma grande aplicação muitos. O sistema particular aqui apresentado foi propositadamente construídos para estudar as propriedades de ...

<table border="1"><tbody><tr><td> Nome do reagente </td><td> Companhia </td><td> Número de catálogo </td><td> Comentários (opcional) </td></tr><tr><td> Máquina de ultra-som </td><td> GE </td><td> Pro Vivid 7 </td><td></td></tr><tr><td> Matriz de ultra-som Linear </td><td> GE </td><td> 10 L </td><td></td></tr><tr><td> DC bomba de água </td><td> KNF </td><td> NF 10 KPDC </td><td></td></tr><tr><td> Vector Processing Software </td><td> Lavision </td><td> Davis 7,2 </td><td></td></tr><tr><td> Publicar Software de Processamento </td><td> Mathworks </td><td> MATLAB 7,12 </td><td></td></tr><tr><td> Tubulação acrílica </td><td> McMaster-Carr </td><td> 8486K531 </td><td></td></tr><tr><td> Gel de ultra-som </td><td> Parker </td><td> Aquasonic 100 </td><td></td></tr></tbody></table>

echo particle image velocimetry

O transporte de massa, momentum e energia em fluxos de fluidos, em última análise determinada por distribuições espaço-temporais do campo de velocidade do fluido. Uma conseqüência, um pré-requisito para a compreensão, previsão e controle dos fluxos de fluidos é a capacidade de medir o campo de velocidade com adequada espacial e resolução temporal. 2 Para medições de velocidade em fluidos opticamente opacos ou através de geometrias opticamente opacos, ecoam velocimetria de partículas de imagem (EPIV) é uma técnica de diagnóstico atrativo para gerar &quot;instantâneas&quot; bidimensionais campos de velocidade. 3,4,5,6 Neste papel, o protocolo de funcionamento de um sistema de EPIV construída através da integração de uma máquina de ultra-som comercial médico 7 com um PC rodando velocimetria de imagem de partículas comercial (PIV) de software 8 é descrito, e medições de validação em Hagen-Poiseuille (ou seja, laminar tubo) fluxo são relatados . Para a medida EPIVmentos, uma sonda de agrupamento por fase ligada à máquina de ultra-som médico é usado para gerar uma imagem de ultra-som bidimensional pulsando os elementos piezoeléctricos de sonda em momentos diferentes. Cada elemento de sonda transmite um impulso de ultra-som para dentro do fluido, e as partículas de marcadores nos fluidos (de ocorrência natural ou semeado) reflectem ecos de ultra-som de volta para a sonda onde são registados. A amplitude das ondas de ultra-som reflectido e seu tempo de atraso em relação à transmissão, são utilizadas para criar o que é conhecido como modo B (modo de luminosidade) imagens bidimensionais de ultra-som. Especificamente, o tempo de atraso é usado para determinar a posição do dispersor no fluido e a amplitude é utilizado para designar a intensidade do espalhador. O tempo necessário para obter uma imagem B de modo único, t, é determinado pelo tempo que leva para pulsar todos os elementos da sonda phased array. Para a aquisição de várias imagens no modo B, a taxa de quadros do sistema em quadros por segundo (fps) = 1 / e delta; t. (Veja 9 para uma revisão de ultra-sonografia.) Para uma experiência típica EPIV, a taxa de fotogramas é entre 20-60 fps, dependendo das condições de fluxo e 100-1000 B-modo imagens da distribuição espacial das partículas no fluxo de traçadores foram adquiridos. Uma vez adquirido, as imagens de ultra-som modo B são transmitidos através de uma conexão ethernet para o PC rodando o software PIV comercial. Utilizando o software de PIV, os campos de deslocação das partículas de rastreamento, D (x, y) [pixels], (em que x e y indicam horizontal e vertical, a posição espacial da imagem de ultra-som, respectivamente) foram adquiridos através da aplicação de algoritmos de correlação cruzada para ultra-som sucessivo B- Imagens no modo. 10 Os campos de velocidade, u (x, y) [m / s], são determinados a partir dos campos de deslocamentos, sabendo que o passo de tempo entre pares de imagens, AT [s] e ampliação da imagem, M [metros / pixel ], ou seja, u (x, y) = MD (x, y) / AT. O passo b momentontre imagens AT = 1/fps + D (x, y) / B, em que B [pixels / s] é o tempo que leva para que a sonda de ultra-som para varrer toda a largura da imagem. No presente estudo, M = 77 [um / pixel], fps = 49,5 [1 / s], e B = [25047 pixels / s]. Uma vez adquirido, os campos de velocidade podem ser analisados ​​para calcular as quantidades de escoamento de interesse.

Uma partícula imagem instantânea de eco velocimetria campo vectorial (EPIV) é mostrado na Figura 3. A trama mostra vetor vetores de velocidade a cada quarta coluna, a cor de fundo e mapa de contorno corresponde à magnitude de velocidade. Um conjunto trama vector médio em média mais de 1000 parcelas vetor instantâneos EPIV é mostrado na Figura 4. Consistente com o fluxo de tubo, os vectores de velocidade são primariamente na direcção streamwise, as maiores velocidades de ocorr...

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Echo Particle Image Velocimetry

Um eco partícula imagem velocimetria sistema (EPIV) capaz de adquirir bidimensionais campos de velocidade em fluidos opacos opticamente ou através de geometrias opticamente opacas é descrita, e as medições de validação no fluxo do tubo são relatados.

Echo Velocimetria por Imagem de Partículas

The transport of mass, momentum, and energy in fluid flows is ultimately determined by spatiotemporal distributions of the fluid velocity field.1 ...

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14.5K visualizações.  University of New Hampshire. Um eco partícula imagem velocimetria sistema (EPIV) capaz de adquirir bidimensionais campos de velocidade em fluidos opacos opticamente ou através de geometrias opticamente opacas é descrita, e as medições de validação no fluxo do tubo são relatados.

Vídeo: Echo Particle Image Velocimetry

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.

The gradient echo memory is a protocol for storing optical quantum states of light in atomic ensembles. Quantum memory is a key element of a quantum repeater, which can extend the range of quantum key distribution. We outline the operation of the scheme when implemented in a 3-level atomic ensemble.

Gradiente eco Quantum Memória em Warm Atomic Vapor

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

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High-speed Particle Image Velocimetry Near Surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. 
Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (&gt; 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows.
A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included.

A procedure for studying transient flows near boundaries using high-resolution, high-speed particle image velocimetry (PIV) is described here. PIV is a non-intrusive measurement technique applicable to any optically accessible flow by optimizing several parameter constraints such as the image and recording properties, the laser sheet properties, and analysis algorithms.

Alta velocidade da partícula Velocimetry Imagem perto de superfícies

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The ...

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

Usando neutron spin echo resolvi a dispersão da incidência de pastagem para investigar materiais orgânicos de células solares

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

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.

Caracterização de nanocristal Tamanho Distribution utilizando Espectroscopia Raman com um Multi-partícula Phonon Confinamento Modelo

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

Development of an Experimental Setup for the Measurement of the Coefficient of Restitution under Vacuum Conditions

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their behavior for single stages of a process or even an entire process. For the simulation with occurring particle-particle and particle-wall contacts, the value of the coefficient of restitution is required. It can be determined experimentally. The coefficient of restitution depends on several parameters like the impact velocity. Especially for fine particles the impact velocity depends on the air pressure and under atmospheric pressure high impact velocities cannot be reached. For this, a new experimental setup for free-fall tests under vacuum conditions is developed. The coefficient of restitution is determined with the impact and rebound velocity which are detected by a high-speed camera. To not hinder the view, the vacuum chamber is made of glass. Also a new release mechanism to drop one single particle under vacuum conditions is constructed. Due to that, all properties of the particle can be characterized beforehand.

The coefficient of restitution is a parameter that describes the loss of kinetic energy during collision. Here, a free-fall setup under vacuum conditions is developed to be able to determine the coefficient of restitution parameter for particles in micrometer range with high impact velocities.

Desenvolvimento de uma instalação experimental para a medição do coeficiente de restituição sob condições de vácuo

The Discrete Element Method is used for the simulation of particulate systems to describe and analyze them, to predict and afterwards optimize their ...

Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

In this article, an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering is presented. Results on the emission of engineered nanomaterials, in the form of aerosols are presented. The specific experimental set-up is described in detail.

Protocolo Experimental para investigar Particle aerossolização de um produto Segundo abrasão e Sub Weathering Ambiental

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental ...

Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic recording of image sequences. The basic components, features, constraints and optimization tips of a 3D-PTV topology consisting of a high-speed camera with a four-view splitter are described and discussed in this article. The technique is applied to the intermediate flow field (5 &#60;x/d &#60;25) of a circular jet at Re &#8776; 7,000. Lagrangian flow features and turbulence quantities in an Eulerian frame are estimated around ten diameters downstream of the jet origin and at various radial distances from the jet core. Lagrangian properties include trajectory, velocity and acceleration of selected particles as well as curvature of the flow path, which are obtained from the Frenet-Serret equation. Estimation of the 3D velocity and turbulence fields around the jet core axis at a cross-plane located at ten diameters downstream of the jet is compared with literature, and the power spectrum of the large-scale streamwise velocity motions is obtained at various radial distances from the jet core.

A three-dimensional particle tracking velocimetry (3D-PTV) system based on a high-speed camera with a four-view splitter is described here. The technique is applied to a jet flow from a circular pipe in the vicinity of ten diameters downstream at Reynolds number Re &#8776; 7,000.

Tridimensional Velocímetro de Partículas de Rastreamento for Applications Turbulência: Case de um fluxo de Jet

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic ...

Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.

The technique described herein offers a low cost and relatively simple method to simultaneously measure particle kinematics and turbulence in flows with low particle concentrations. The turbulence is measured using particle image velocimetry (PIV), and particle kinematics are calculated from images obtained with a high-speed camera in an overlapping field-of-view.

Medição simultânea de turbulência e cinemática das partículas usando o fluxo de imagens técnicas

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine ...

3D Printing - Evaluating Particle Emissions of a 3D Printing Pen

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament fabrication (FFF) is an inexpensive method used most frequently by consumers. Studies with 3D printers have shown that during the printing process particulate and volatile substances are released. Handheld 3D printing pens also use the FFF method but the consumer&#8217;s proximity to the 3D pens gives reason to higher exposure compared to a 3D printer. At the same time, 3D printing pens are often marketed for children who could be more sensitive to the printing emission. The aim of this study was to implement a low cost method to analyze the emissions of 3D printing pens. Polylactide (PLA) and acrylonitrile butadiene styrene (ABS) filaments of different colors were tested. In addition, filaments containing metal and carbon nanotubes (CNTs) were analyzed. An 18.5 L chamber and sampling close to the emission source was used to characterize emissions and concentrations near the breathing zone of the user.
Particle emissions and particle size distributions were measured and the potential release of metal particles and CNTs investigated. Particle number concentrations were found in a range of 105 - 106 particles/cm3, which is comparable to previous reports from 3D printers. Transmission electron microscopy (TEM) analysis showed nanoparticles of the different thermoplastic materials as well as of metal particles and CNTs. High contents of metal were observed by inductively coupled plasma mass spectrometry (ICP-MS).
These results call for a cautious use of 3D pens due to potential risk to the consumers.

This protocol presents a method to analyze the emission of 3D printing pens. Particle concentration and particle size distribution of the released particle is measured. Released particles are further analyzed with transmission electron microscopy (TEM). Metal content in filaments is quantified by inductively coupled plasma mass spectrometry (ICP-MS).

Impressão 3D - Avaliando emissões de partículas de uma caneta de impressão 3D

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament ...

Study of Protein Dynamics via Neutron Spin Echo Spectroscopy

Most human body proteins' activity and functionality are related to configurational changes of entire subdomains within the protein crystal structure. The crystal structures build the basis for any calculation that describes the structure or dynamics of a protein, most of the time with strong geometrical restrictions. However, these restrictions from the crystal structure are not present in the solution. The structure of the proteins in the solution may differ from the crystal due to rearrangements of loops or subdomains on the pico to nanosecond time scale (i.e., the internal protein dynamics time regime). The present work describes how slow motions on timescales of several tens of nanoseconds can be accessed using neutron scattering. In particular, the dynamical characterization of two major human proteins, an intrinsically disordered protein that lacks a well-defined secondary structure and a classical antibody protein, is addressed by neutron spin echo spectroscopy (NSE) combined with a wide range of laboratory characterization methods. Further insights into protein domain dynamics were achieved using mathematical modeling to describe the experimental neutron data and determine the crossover between combined diffusive and internal protein motions. The extraction of the internal dynamic contribution to the intermediate scattering function obtained from NSE, including the timescale of the various movements, allows further vision into the mechanical properties of single proteins and the softness of proteins in their nearly natural environment in the crowded protein solution.

Study of Protein Dynamics via Neutron Spin Echo Spectroscopy

The present protocol describes methods for investigating the structure and dynamics of two model proteins that have an important role in human health. The technique combines bench-top biophysical characterization with neutron spin echo spectroscopy to access the dynamics at time and length scales relevant for protein interdomain motions.

Estudo da Dinâmica da Proteína via Espectroscopia de Eco de Neutron Spin

Most human body proteins' activity and functionality are related to configurational changes of entire subdomains within the protein crystal structure. The ...