Este trabalho foi suportado pelo Grant No. CBET-0651283 da National Science Foundation EUA e n º Grant 117041PO9621 de Tecnologia de arrefecimento avançado.

1. Preparação de sílica nanopartículas para Deposição <ol><li> Começando com pó de sílica seco, preparar a amostra para o revestimento por primeiro eliminando grandes agregados. </li><li> Lavar partículas de sílica (diâmetro de 200 nm, comprado de Gel-Tec Corp) com etanol (190 prova puro) e deixar a amostra sob uma coifa até que todos os que a umidade evapore com etanol. </li><li> Peneirar partículas através de uma série de malhas metálicas (EUA # 100-400), a fim de quebrar quaisquer aglomerações restantes. </li><li> Partículas lugar e uma barra de agitador magnético pequeno no reactor tubular, como mostrado na Figura 1. Partículas deve ser colocado dentro da zona de plasma. </li><li> Selar o reactor de vidro, colocando um o-ring entre duas flanges, uma no final do tubo de vidro e um na extremidade do tubo ligado à bomba. </li><li> Instalar o anel de aperto de aço inoxidável em torno do flanges e mão apertar o parafuso de torno do grampo. </li></ol> 2.Preparação do sistema de vácuo <ol><li> Encher a armadilha de azoto líquido, então permitir que a superfície da armadilha para se tornar a frio. Espere 5 min. </li><li> Adicionar isopropanol no borbulhador e conectar-se ao reator de plasma. </li><li> Selar o borbulhador pela colocação de um anel de borracha em torno do tubo de metal e apertar a porca até ao local de ligação ao tubo de borbulhador torna-se selado. </li></ol> 3. Plasma processo de deposição <ol><li> Coloque a borbulhador num banho de água com temperatura de 34 ± 2 ° C. </li><li> Ligue o controlador de fluxo de gás argônio e entre 6,00 sccm como o set point. </li><li> Gradualmente abrir a válvula de porta que liga o tubo de vidro para a bomba enquanto a bomba está a funcionar. Execute esta etapa com cuidado, pois queda súbita de pressão pode fazer com que as partículas a serem levados pelo fluxo. Espere até que a pressão atinge 200 mTorr, em seguida, deixar a válvula de gaveta totalmente aberta. </li><li> Colocar o agitador magnético sob o tubo de vidro e ajustar a velocidade de 100 rpm. </li><li> Ligue o anel de alumínio em torno do reactor de vidro tubular para a frequência de rádio, RF, gerador e ligar o grampo de aço inoxidável para o chão. </li><li> Ligue a rede correspondente (ENI MW-5D) primeiro e depois mudar a linha AC e do poder gerador de RF. Regule a potência em 30 W para todo o processo. </li><li> Depois de uma duração de tempo específico (10, 20, ou 40 min) desligar a rede correspondente, o gerador de RF, e à energia de CA, respectivamente. </li><li> Feche a válvula de retenção e, em seguida, desligar o controlador de fluxo de argônio. Desligue o borbulhador da válvula e aumentar gradualmente a pressão do reactor para atmosférica. </li><li> Abrir a braçadeira e transferir as partículas a partir do tubo em um prato de plástico usando uma espátula metálica. </li></ol> 4. Preparação de partículas ocas por dissolução de material do núcleo <ol><li> Colocar a amostra sob um exaustor para todo o processo de adição de ácido fluorídrico. </li><li> Ácido fluorídrico é um extremamente coácido rrosive e exposição dos olhos e pele pode causar danos permanentes. Usar óculos com protetor facial e vestir uma bata de laboratório quando manusear HF. </li><li> Misturar 10 ml de ácido fluorídrico (Aldrich 49%) com 10 ml de água desionizada e adicionar ao prato de plástico que contém as partículas revestidas. </li><li> Coloque o prato de plástico sobre um agitador magnético e permitir que o núcleo para dissolver durante 24 horas. </li><li> Após um dia diluir a amostra com 50 ml de água desionizada e centrifugar a amostra durante 1 hora. Descartar a camada de líquido no topo num recipiente de plástico e transferir a camada inferior que contém as partículas numa placa de Petri de plástico. </li><li> Adicionar 50 ml de água deionizada e vortex e centrifugar a amostra-lo novamente. Elimine a camada superior e transferir a camada de partículas numa placa de Petri limpa. </li><li> Lavar as partículas com etanol, o ar seco a amostra, e transferir partículas ocas em um frasco com tampa e manter as partículas num exsicador. </li></ol> 5. Characterization de Permeabilidade (taxa de libertação Core) Materiais: cloreto de potássio para materiais de núcleo <ol><li> Preparar 0,001 molar de cloreto de potássio solução (KCl) por mistura de 0.0745 gramas de KCl com 1 litro de água desionizada. </li><li> Encha a garrafa de vidro do modelo constante saída atomizador 3076 e instalar a tampa da garrafa. </li><li> Ligar a mangueira de ar comprimido para um secador de membrana, que está ligado à entrada de gás do atomizador. Em seguida, anexar um filtro para a mangueira de saída a fim de recolher as nanopartículas de KCl. </li><li> Aos poucos, abrir a válvula de ar comprimido e deixar o fluxo de ar através do secador de membrana. Permitir que as partículas se acumulam no filtro durante 5 horas. </li><li> Feche a válvula de ar comprimido e remova cuidadosamente o filtro e recolher as partículas. Colocar as partículas em um exsicador antes do processo de revestimento. </li><li> Seguir o protocolo 2 e 3, a fim de obter partículas revestidas uniformemente KCl. </li><li> Misturar KCl revestido com 10 ml desionizada water em um frasco de vidro. Para totalmente misturar a amostra, gota um agitador magnético na solução e deixá-lo sobre um agitador magnético. Incubar a amostra a 25 ° C. </li><li> Insira a condutividade metros sonda (Thermo Orion modelo 105) dentro do frasco e gravar a condutividade mais de 30 dias. </li></ol> 6. Os resultados representativos Temos aplicado este processo a uma variedade de materiais do núcleo, incluindo óxidos (sílica), sais (KCl) e metais (Al), como mostrado na Figura 2. Microscópio de transmissão de electrões foi usado para confirmar a uniformidade radial dos filmes e para medir a sua espessura. Conseguimos partículas revestidas que variam de 37 nm a 200 nm de diâmetro (Figura 2), mas não há nenhuma limitação fundamental sobre o tamanho das partículas que podem ser tratados por este método. A taxa de deposição de concha é de aproximadamente 1 nm / min. Esta taxa mais lenta torna possível para controlar a espessura dos filmes bastantecom precisão através do tempo de deposição. A concha de plasma-polimerizado é uma barreira permeável, como demonstrado pelo facto de o material do núcleo pode ser removida por ataque químico ou a dissolução. A Figura 3 mostra as conchas ocas que permanecem após o núcleo de sílica é removido. A remoção do núcleo está completa ea uniformidade radial e espessura dos filmes são bastante elevados. Para efeitos de avaliação da permeabilidade através destes filmes, que mudou para KCl como o material do núcleo desde a dissolução de KCl pode ser controlada muito facilmente através da condutividade iónica da solução. Figura 4 mostra a libertação de KCl a partir do núcleo para quatro amostras com espessura diferente, 20 nm, 40 nm, 75 nm, e 95 nm, respectivamente. Partículas revestidas de KCl foram suspensas em água ea condutividade da solução foi seguido por um período de 30 dias. Para além das quatro amostras, um controle que consiste em partículas não revestidas KCl foi também monitorizada. Não revestidos partículas de KCl dissociaçãoLVe dentro de um tempo muito curto de cerca de 1 min. Em contraste, KCl revestido mostra uma taxa de libertação significativamente mais lenta. O perfil de libertação das partículas revestidas é caracterizada por explosão inicial que ocorre dentro do hr primeiro, seguido por uma libertação muito mais lenta que leva vários dias para completar, dependendo da espessura do filme. <img alt="A Figura 1" src="/files/ftp_upload/4113/4113fig1.jpg" /> Figura 1. Representação esquemática da preparação de nanopartículas, deposição de plasma, e de formação de partículas ocas. <img alt="A Figura 2" src="/files/ftp_upload/4113/4113fig2.jpg" /> Figura 2. Imagens de TEM de revestimento (a), (b) partículas de sílica com d = 200 nm, (c) de partículas de sílica com d = 37 nm, (d) de alumínio com d ~ 100 nm, e (e) de partículas de KCl com D = 100 nm <img alt="A Figura 3" src="/files/ftp_upload/4113/4113fig3.jpg" /> Figura 3. TEM imagens de partículas ocas após decapagem (a), o núcleo de sílica (b) com diâmetro de 200 nm, e (c) do núcleo de KCl. <img alt="A Figura 4" src="/files/ftp_upload/4113/4113fig4.jpg" /> Figura 4. Efeito da espessura da casca sobre o perfil de liberação. O gráfico mostra a inserção de liberação durante o hr primeiro.

<ol>
	<li>Xu, X., Asher, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Utilization+of+Monodisperse+Hollow+Polymeric+Particles+in+Photonic+Crystals.">Synthesis and Utilization of Monodisperse Hollow Polymeric Particles in Photonic Crystals.</a> Journal of the American Chemical Society. 126, 7940-7945 (2004).</li><li>Lou, X., Archer, L., Yang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hollow+Micro-/nanostructures:+Synthesis+and+Applications.">Hollow Micro-/nanostructures: Synthesis and Applications.</a> Advanced Material. 20, (2008).</li><li>Kim, D. J., Kang, J. Y., Kim, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coating+of+TiO2+Thin+Films+on+Particles+by+a+Plasma+Chemical+Vapor+Deposition+Process.">Coating of TiO2 Thin Films on Particles by a Plasma Chemical Vapor Deposition Process.</a> Advanced Powder Technology. 21, 136-140 (2010).</li><li>Marino, E., Huijser, T., Creyghton, Y., van der Heijden, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Coating+of+Copper+Oxide+Nanoparticles+Using+Atmospheric+Pressure+Plasmas.">Synthesis and Coating of Copper Oxide Nanoparticles Using Atmospheric Pressure Plasmas.</a> Surface and Coatings Technology. 201, 9205-9208 (2007).</li><li>Hakim, L., King, D., Zhou, Y., Gump, C., George, S., Weimer, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+Coating+for+Advanced+Optical,+Mechanical+and+Rheological+Properties.">Nanoparticle Coating for Advanced Optical, Mechanical and Rheological Properties.</a> Advanced Functional Materials. 17, 3175-3181 (2007).</li><li>Kim, S. H., Kim, J., Kang, B., Uhm, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superhydrophobic+CFx+Coating+via+In-Line+Atmospheric+RF+Plasma+of+He-CF4-H2.">Superhydrophobic CFx Coating via In-Line Atmospheric RF Plasma of He-CF4-H2.</a> Langmuir. 21, 12213-12217 (2005).</li></ol>

Não há conflitos de interesse declarados.

Um dos maiores desafios em nanopartículas de revestimento é o de proporcionar uma química compatível entre o revestimento eo substrato 1,2. A metodologia aqui descrita tem a vantagem de que não é o material específico. Polímeros de plasma mostram excelente adesão sobre uma variedade de substratos, incluindo metais duros (Figura 2 (c)), sílica (Figura 2 (c)), silício, ou materiais macios (por exemplo, polímeros) sem a necessidade de qualquer modificação da superf...

<table border="1"><tbody><tr><td> Partículas de sílica </td><td> Geltech Inc. </td><td></td><td></td></tr><tr><td> Cloreto de potássio (cristais) </td><td> Merck </td><td></td><td></td></tr><tr><td> Álcool isopropílico (99,9%) </td><td> Sigma-Aldrich </td><td></td><td></td></tr><tr><td> Ácido fluorídrico (48-51%) </td><td> VWR </td><td></td><td></td></tr><tr><td> Tubos e flanges </td><td> Swagelok </td><td></td><td> diâmetro de ¼ e 1 polegada </td></tr><tr><td> desbaste bomba </td><td> Edwards </td><td></td><td></td></tr><tr><td> armadilha de nitrogênio líquido </td><td> A &amp; N Corporação </td><td></td><td></td></tr></tbody></table>

encapsulation and permeability characteristics of plasma polymerized hollow particles

Neste protocolo, core-shell nanoestruturas são sintetizados por plasma melhorada deposição de vapor químico. Produzimos um barreira amorfo por plasma de polimerização de isopropanol em vários substratos sólidos, incluindo sílica e cloreto de potássio. Esta técnica versátil é utilizado para tratar as nanopartículas e nanopós com tamanhos que vão desde 37 nm a 1 micron, por depositar películas cuja espessura pode estar em qualquer lugar a partir de 1 nm a para cima de 100 nm. Dissolução do núcleo permite estudar a taxa de permeação através da película. Nestas experiências, nós determinar o coeficiente de difusão de KCl através da película de barreira por nanocristais KCl de revestimento e subsequentemente o controlo da condutividade iónica das partículas revestidas em suspensão na água. O interesse principal neste processo é o encapsulamento e de libertação retardada de solutos. A espessura da casca é uma das variáveis ​​independentes pelo qual controlam a taxa de libertação. Ele tem um forte efeito sobre a taxade lançamento, o que aumenta a partir de uma versão de seis horas (a espessura da casca é de 20 nm) para um lançamento longo prazo mais de 30 dias (a espessura da casca é de 95 nm). O perfil de libertação mostra um comportamento característico: uma libertação rápida (35% dos materiais finais) durante os primeiros cinco minutos após o início da dissolução, e uma libertação mais lenta até todos os materiais do núcleo sair.

Watch this Scientific Journal Video about Encapsulation and Permeability Characteristics of Plasma Polymerized Hollow Particles at JoVE.com

Encapsulation and Permeability Characteristics of Plasma Polymerized Hollow Particles

Usámos plasma melhorada deposição de vapor químico para depositar películas finas que variam de um nm poucos a vários 100 nm sobre nano-partículas de vários materiais. Nós subsequentemente etch o material do núcleo para produzir nanoshells ocos cuja permeabilidade é controlado pela espessura da casca. Nós caracterizar a permeabilidade destes revestimentos para solutos pequenas e demonstram que estas barreiras podem proporcionar uma libertação sustentada do material do núcleo durante vários dias.

Encapsulamento e Permeabilidade características das partículas de plasma polimerizados ocas

In this protocol, core-shell nanostructures are synthesized by plasma enhanced chemical vapor deposition. We produce an amorphous barrier by plasma ...

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10.6K visualizações.  The Pennsylvania State University. Usámos plasma melhorada deposição de vapor químico para depositar películas finas que variam de um nm poucos a vários 100 nm sobre nano-partículas de vários materiais. Nós subsequentemente etch o material do núcleo para produzir nanoshells ocos cuja permeabilidade é controlado pela espessura da casca. Nós caracterizar a permeabilidade destes revestimentos para solutos pequenas e demonstram que estas barreiras podem proporcionar uma libertação sustentada do m...

Vídeo: Encapsulation and Permeability Characteristics of Plasma Polymerized Hollow Particles

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11.
Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps).
Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators.

An experimental method to examine the early plasma evolution induced by ultrashort laser pulses is described. Using this method, high quality images of early plasma are obtained with high temporal and spatial resolutions. A novel integrated atomistic model is used to simulate and explain the mechanisms of early plasma.

Investigação da Evolução Plasma Precoce Induzida por Pulsos ultracurtos de laser

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a ...

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Experimental Measurement of Settling Velocity of Spherical Particles in Unconfined and Confined Surfactant-based Shear Thinning Viscoelastic Fluids

An experimental study is performed to measure the terminal settling velocities of spherical particles in surfactant based shear thinning viscoelastic (VES) fluids. The measurements are made for particles settling in unbounded fluids&#160;and fluids between parallel walls. VES fluids over a wide range of rheological properties are prepared and rheologically characterized. The rheological characterization involves steady shear-viscosity and dynamic oscillatory-shear measurements to quantify the viscous and elastic properties respectively. The settling velocities under unbounded conditions are measured in beakers having diameters at least 25x the diameter of particles. For measuring settling velocities between parallel walls, two experimental cells with different wall spacing are constructed. Spherical particles of varying sizes are gently dropped in the fluids and allowed to settle. The process is recorded with a high resolution video camera and the trajectory of the particle is recorded using image analysis software. Terminal settling velocities are calculated from the data.
The impact of elasticity on settling velocity in unbounded fluids is quantified by comparing the experimental settling velocity to the settling velocity calculated by the inelastic drag predictions of Renaud et al.1&#160;Results show that elasticity of fluids can increase or decrease the settling velocity. The magnitude of reduction/increase is a function of the rheological properties of the fluids and properties of particles. Confining walls are observed to cause a retardation effect on settling and the retardation is measured in terms of wall factors.

This paper demonstrates the experimental procedure to measure terminal settling velocities of spherical particles in surfactant-based shear thinning viscoelastic fluids. Fluids over a wide range of rheological properties are prepared and settling velocities are measured for a range of particle sizes in unbounded fluids and fluids between parallel walls.

Medição experimental da velocidade de assentamento de partículas esféricas em fluidos viscosticos não confinados e confinados

An experimental study is performed to measure the terminal settling velocities of spherical particles in surfactant based shear thinning viscoelastic ...

How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators &#8212; a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes.

This movie shows how an atmospheric plasma torch can be ignited by microwaves with no additional igniters and provides a stable and continuous plasma operation suitable for plenty of applications.

Como inflamar uma pressão atmosférica Microondas Plasma Torch sem qualquer Ignitores adicionais

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

Métodos para medir a orientação e rotação Taxa de partículas em Turbulência 3D-impressos

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

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.

Fabricação e operação de Acoustofluidic dispositivos que suportam a granel ondas acústicas pe para Sheathless Focando de Partículas

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

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line intensity ratios. By using a Johann spectrometer viewing the plasma, it is possible to construct profiles of plasma parameters such as density, temperature, and velocity with good spatial and time resolution. However, benchmarking atomic code modeling of X-ray spectra obtained from well-diagnosed laboratory plasmas is important to justify use of such spectra to determine plasma parameters when other independent diagnostics are not available. This manuscript presents the operation of the High Resolution X-ray Crystal Imaging Spectrometer with Spatial Resolution (HIREXSR), a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma. In addition, this manuscript covers a laser blow-off system that can introduce such ions to the plasma with precise timing to allow for perturbative studies of transport in the plasma.

X-ray spectra provide a wealth of information on high temperature plasmas. This manuscript presents the operation of a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma.

Aplicando raios-X de imagem de cristal Spectroscopy para uso como uma alta temperatura do plasma de diagnóstico

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line ...

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling immensely. However, in soft electronics, in which organic semiconductors play a critical role, the devices will be bent or folded repeatedly. The effect of bending on the crystal packing and thus the charge transport is crucial to the performance of the device. In this manuscript, we describe the protocol to bend a single crystal of 5,7,12,16-tetrachloro-6,13-diazapentacene (TCDAP) in the field-effect transistor configuration and to obtain reproducible I-V characteristics upon bending the crystal. The results show that bending a field-effect transistor prepared on a flexible substrate results in nearly reversible yet opposite trends in charge mobility, depending on the bending direction. The mobility increases when the device is bent toward the top gate/dielectric layer (upward, compressive state) and decreases when bent toward the crystal/substrate side (downward, tensile state). The effect of bending curvature was also observed, with greater mobility change resulting from higher bending curvature. It is suggested that the intermolecular &#960;-&#960; distance changes upon bending, thereby influencing the electronic coupling and the subsequent carrier transport ability.

This manuscript describes the bending process of an organic single crystal-based field-effect transistor to maintain a functioning device for electronic property measurement. The results suggest that bending causes changes in the molecular spacing in the crystal and thus in the charge hopping rate, which is important in flexible electronics.

Efeito da flexão no Características elétricas dos transistores de efeito de campo baseados em cristal flexível Orgânico Um único

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling ...

An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

Non-thermal atmospheric pressure (&#39;cold&#39;) plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to plasma are still scarce. Biomedical plasma is often operated with He or Ar feed gas, and a specific interest lies in investigation of the reactive species generated by plasma with various gas admixtures (O2, N2, air, H2O vapor, etc.) Such investigations are very complex due to difficulties in controlling the ambient atmosphere in contact with the plasma effluent. In this work, we addressed common issues of &#39;high&#39; voltage kHz frequency driven plasma jet experimental studies. A reactor was developed allowing the exclusion of ambient atmosphere from the plasma-liquid system. The system thus comprised the feed gas with admixtures and the components of the liquid sample. This controlled atmosphere allowed the investigation of the source of the reactive oxygen species induced in aqueous solutions by He-water vapor plasma. The use of isotopically labelled water allowed distinguishing between the species originating in the gas phase and those formed in the liquid. The plasma equipment was contained inside a Faraday cage to eliminate possible influence of any external field. The setup is versatile and can aid in further understanding the cold plasma-liquid interactions chemistry.

An experimental setup was created for the helium-operated kHz frequency plasma jet. The setup includes a cage for the plasma power supply and jet and an in-house built reactor to monitor plasma-induced reactive species without the interference of the ambient atmosphere.

Uma configuração Plasma Pressão atmosférica para investigar a formação de espécies reativas

Non-thermal atmospheric pressure (&#39;cold&#39;) plasmas have received increased attention in recent years due to their significant biomedical potential. ...

Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with one twist grain boundary. This apparatus utilizes high uniaxial pressure and a pulsed direct current for rapid consolidation of material. Diffusion bonding of strontium titanate bicrystals without fracture, in a spark plasma sintering apparatus, is possible at high pressures due to the unusual temperature dependent plasticity behavior of strontium titanate. We demonstrate a method for the successful formation of bicrystals at accelerated time scales and lower temperatures in a spark plasma sintering apparatus compared to bicrystals formed by conventional diffusion bonding parameters. Bond quality was verified by scanning electron microscopy. A clean and atomically abrupt interface containing no secondary phases was observed using transmission electron microscopy techniques. Local changes in bonding across the boundary was characterized by simultaneous scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy.

A viable technique for the formation of strontium titanate bicrystals at high pressure and fast heating rate via the spark plasma sintering apparatus is developed.

Faísca Plasma Sintering aparelho utilizado para a Formação de titanato de estrôncio Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

Otimização, teste e diagnóstico dos propulsores miniaturizados Hall

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...