This research was funded by the International Research Training Group (IRTG) &#8220;Diffusion in porous Materials&#8221;. We acknowledge the technical support from Gert Klotzsche and stimulating discussions with Steven Reichhardt, Thomas Meissner, Damian Rybicki, Tobias Herzig, Natalya Georgieva, Jonas Kohlrautz, and Michael Jurkutat.

1. montaje y alineación de las 6H-SiC grande del Cono Yunques de tipo Boehler <ol><li> Fijar el pistón y la placa xy en las herramientas de montaje e inserte los yunques de tipo Boehler en la zona de estar. </li><li> Asegúrese de que cada yunque se sienta firmemente en las placas de apoyo. </li><li> El uso de resina epoxi, (por ejemplo, Stycast 1266), pega dos yunques a sus asientos. Cure durante 12 horas a temperatura ambiente o 65 º C en un horno durante 2 horas. </li><li> Para una alineación suficiente yunque, utilice los tornillos de ajuste M1 para alinear las placas de apoyo y controlar el paralelismo de los dos yunques. Si no se encuentran los yunques que no paralela, eliminar la resina epoxi y reiniciar en el punto 1.2. </li></ol> 2. Preparación de juntas <ol><li> Taladro 1 mm Agujeros en un chip de recocido Cu-Be (Cu 98% w, Be 2% en peso, espesor de 0,5 mm) para los pernos de guía de latón. </li><li> Inserte tres 5 mm de largo piezas de alambre de cobre sin aislamiento 1 mm de diámetro en los agujeros, que se distribuyen a lo largo del yunque, para servir como guidpines electrónicos para la junta de Cu-Be. </li><li> Compruebe la conexión a tierra adecuado entre los pasadores de guía y el cuerpo celular. Por lo general, se desea una resistencia de corriente continua de aproximadamente 0,1 Ω. Mejorar con una aplicación de una pequeña cantidad de plata conductora. </li><li> Coloque el chip Cu-Be en la parte superior del yunque moissanite y cerrar la celda. </li><li> Usando una prensa hidráulica, presurizar la junta a aproximadamente un octavo del diámetro º culet para la estabilidad de trabajo maximizada. Controle el espesor real de la huella utilizando un calibrador micrométrico. </li><li> Perforar un agujero de diámetro adecuado (½ del diámetro de la culata) en el centro de la indentación. </li><li> Tallar dos canales en la junta pre-sangría. Los canales deben ser lo suficientemente profundo para acomodar el alambre de 18 micras de cobre de la micro-espiral. </li><li> Harden la junta preparada a 617 K durante 2 a 3 horas en un horno. </li></ol> 3. Preparación y carga de la Micro-coil <ol><li> Use un pedazo de 1 mm de un cable de cobred pásela por la alimentación a través del pistón. Fijar el alambre de cobre con la resina epoxi y curar según la etapa 1.3. </li><li> Elija un punzón (vea la lista de materiales) que tiene el diámetro deseado para el micro-coil y fijarlo entre un par de rotativos mandril de mordazas. </li><li> Pegamento (con, por ejemplo, barniz de SCB, véase la lista de materiales) un extremo del cable de 18 micras de cobre sobre las mordazas del mismo, mientras se mantiene el otro extremo y gire el mordazas para que el alambre se enrolla sobre el punzón. </li><li> Cuando el micro-bobina es de la geometría deseada, fijar el otro extremo del alambre sobre el pegamento también. </li><li> Utilice barniz diluido para fijar la bobina mediante la aplicación de una pequeña cantidad en la parte superior de los devanados. </li><li> Retire la bobina cuidadosamente del punzón usando cinta de teflón. </li><li> Coloque un poco de resina epoxi (véase el punto 1.3), sin ningún tipo de aditivos, en los canales de la junta. </li><li> Coloque el micro-bobina interior de la cámara de la muestra y fijar los cables en los canales. </li><li> Curar el epoxy resina según la etapa 1.3. </li><li> Soldar un cable de la micro-espiral al alambre caliente y el otro a un pasador de guía. </li><li> Agregue un poco de pasta conductora de plata en la parte superior de cada unión. El curado suele durar algunos minutos. </li><li> Sellar ambas uniones con una pequeña cantidad de resina epoxi. </li><li> Curar el epoxi según la etapa 1.3. </li><li> Ahora, compruebe la resistencia DC de la bobina después de cada paso. </li><li> Colocar la muestra en el micro-coil. Tenga en cuenta que cualquier contacto físico innecesario puede destruir la bobina. </li><li> Agregue el polvo de rubí finamente molido a la muestra de calibración de la presión. </li><li> Finalmente, inundar la cámara de muestra con un medio de presión adecuado. Utilice aceite de parafina para garantizar condiciones casi-hidrostáticas de hasta 9 GPa. </li><li> Cierre la celda con cuidado. </li></ol> 4. Aplicación y control de la presión <ol><li> Al principio, apriete ligeramente los tornillos avellanados M3 Allen. </li><li> Para fijar la celda de presurización en un tornillo de banco. Ahora, aprietedos opuestos tornillos por parejas. </li><li> Coloque la celda a presión en un soporte de la celda apropiada. </li><li> Ajustar la posición de la celda de manera que el haz de láser alcanza la cámara de muestra. </li><li> Utilice la tabla de ajuste fino para enfocar el polvo de rubí en el haz de láser. </li><li> Supervisar el espectro de fotoluminiscencia ruby ​​usando el software espectrómetro correspondiente. </li><li> Extraer la presión real en la cavidad de la muestra a partir del desplazamiento espectral observado de las líneas de rubí R1 y R2. </li><li> Equilibrar la celda a presión durante al menos 12 horas antes de que se inicien las mediciones de RMN. </li></ol> 5. la realización de experimentos de RMN <ol><li> Montar la celda de presión sobre una sonda típico de RMN. Fabricación titulares de células apropiadas en un taller mecánico. </li><li> Soldar el alambre caliente a la sonda. Entrada para el contacto eléctrico adecuado entre la célula y la sonda. </li><li> Ahora, realizar experimentos de RMN estándar. Llamar la atención sobre el hecho de que la micro-coil es very sensible a la potencia de radio-frecuencia aplicada. </li></ol>

<ol>
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The authors have nothing to disclose.

Un nuevo y prometedor método para realizar RMN a presiones Giga-Pascal fue descrito. Este método abre la puerta a una amplia variedad de experimentos de RMN debido a su excelente sensibilidad y resolución. Sin embargo, varios pasos que se describen en la sección de protocolo son cruciales para el resultado del experimento. Sobre todo, la preparación de la micro-coil y su fijación en la junta de Cu-Be es muy difícil y requiere un poco de experiencia. A continuación, se dan algunos consejos importantes, que deber?...

Dado que los experimentos sello de Percy Bridgman de la materia condensada bajo presiones hidrostáticas altas al principio del siglo pasado, el campo de la física de alta presión ha evolucionado rápidamente 1. Un gran número de fenómenos intrigantes se sabe que se producen bajo presiones de varios GPa 2. Además, la respuesta de los sistemas de materia condensada a alta presión nos ha enseñado mucho acerca de su planta electrónica y estados excitados 3,4. Desafortunadamente, las técnicas para la investigación de las propiedades electrónicas de la materia condensada a presiones Giga-Pascal son raros, con rayos X o las mediciones de resistencia de corriente continua a la cabeza 5. En particular, la detección de los momentos magnéticos electrónicos o nucleares con spin electrónico (ESR) o la resonancia magnética nuclear (RMN) experimentos, está obligado a ser casi imposible de implementar en un típico células de yunque de alta presión donde uno necesita para recuperar la señal de una pequeña volumen consagrado por yunques y una junta de estanqueidad. Varios grupos han tratado de resolver este problema mediante el uso de arreglos complejos, por ejemplo, dos fracciones de par de radiofrecuencia (RF) bobinas heridos a lo largo de los flancos de los yunques 6; un bucle simple o doble horquilla resonador 7,8; ., o incluso una junta de renio dividida como una bobina de RF de recogida 9, véase la Figura 1 Desafortunadamente, estos enfoques aún sufría de una baja relación señal-ruido (SNR), lo que limita las aplicaciones experimentales a gran - γ núcleos tales como 1 H 10. El lector interesado puede ser referido a otras de alta presión resonantes experimentos circuito tanque 11 - 15. Pravica y Silvera 16 Informe de la presión más alta alcanzada en una celda de yunque de RMN con 12.8 GPa, que estudió la conversión orto-para de hidrógeno. Con gran interés en la aplicación de RMNpara estudiar las propiedades de los sólidos cuánticos, nuestro grupo estaba interesado en tener RMN disponibles a altas presiones, también. Por último, en 2009 se pudo demostrar que la alta sensibilidad RMN celda de yunque de hecho, es posible si una resonancia de radio-frecuencia (RF) micro-bobina se coloca directamente en la cavidad de alta presión que encierra la muestra 17. En tal enfoque, la sensibilidad de RMN se mejora en varios órdenes de magnitud (sobre todo debido al aumento dramático en factor de llenado de la bobina de RF), que hace aún más difícil experimentos de RMN posible, por ejemplo, 17 O RMN en muestras de polvo de un superconductor de alta temperatura a un máximo de 7 GPa 18. La superconductividad en estos materiales se puede amplificar en gran medida por la aplicación de presión, y ahora es posible seguir este proceso con una sonda electrónica local que promete visión fundamental en los procesos de gobierno. Otro ejemplo para el poder de RMN a alta presión surgió de lo que eran Believed para ser experimentos de referenciación de rutina: con el fin de probar la nueva RMN celda de yunque de una presentación, uno de los materiales más conocidos se midió - sencillo de metal de aluminio. Como se aumentó la presión, se encontró una desviación inesperada del cambio de RMN de lo que uno puede esperar de un sistema de electrones libres. Experimentos repetidos, también debajo de aumento de las presiones, mostraron que los nuevos resultados eran realmente fiable. Por último, con cálculos de estructura de banda se encontró entonces que los resultados son la manifestación de una transición topológica de la superficie de Fermi de aluminio, que no pudo ser detectado por los cálculos de años atrás, cuando la potencia de cálculo era baja. La extrapolación de los resultados a las condiciones ambientales mostró que las propiedades de este metal que se utiliza en casi todas partes están influenciadas por esta condición electrónico especial. Con el fin de seguir una serie de aplicaciones diferentes células de yunque especialmente diseñados (células anteriores se habían importado de la Cavendish de laboratorio y readaptado para RMN) se han desarrollado. Actualmente, el chasis de fabricación casera utilizados son capaces de alcanzar presiones de hasta 25 GPa usando un par de yunques 800 micras Culet 6H-SiC. Experimentos de RMN se llevaron a cabo con éxito hasta 10.1 GPa, hasta ahora. El rendimiento de RMN de este nuevas células ha demostrado ser excelente 19. El componente principal es de titanio-aluminio (6) -Vanadium (4) con un bajo nivel intersticial adicional (grado 23), proporcionando una resistencia a la fluencia de aproximadamente 800 MPa 20. Debido a sus propiedades no magnéticas (χ la susceptibilidad magnética es de aproximadamente 5 ppm) es un material adecuado para el chasis de células yunque. Las dimensiones totales de las células introducidas (véase la Figura 2 para una visión general de todos los diseños de celda de yunque de fabricación casera) son lo suficientemente pequeños para caber en los imanes de RMN taladro estándar regulares. El diseño más pequeño, el LAC-TM1, que está a sólo 20 mm de altura y 17 mm de diámetro, también válido, imanes frío calibre pequeños típicos (30 mm diámetro del agujero). La LAC-TM2, que es el último chasis los autores diseñaron, utiliza cuatro tornillos avellanados M4 Allen (hechas de la misma aleación que el chasis de células) como mecanismo de accionamiento de presión, lo que permite un control suave de la presión interna (planos adjuntos, en los sección suplementaria). Típicamente, los yunques de diamante se utilizan con el fin de generar presiones más altas de por encima de 100 GPa. Xu y Mao 21 - 23 han demostrado que los yunques moissanite proporcionan una alternativa rentable en la investigación de alta presión, hasta presiones de aproximadamente 60 GPa. Por lo tanto, se utilizaron los yunques moissanite para el enfoque GPa RMN introducido. Los mejores resultados se lograron con personalizados yunques-cono grande 6H-SiC del departamento de yunque de Charles &amp; Colvard. Con esas células, para presiones de hasta 10,1 GPa, se encontró que el uso de 800 micras yunques Culet a resultar en muy buena sensibilidad RMN. Para la comparación, Lee et al. Informan una SNR de 1 por 1 H NMR de agua del grifo, mientras que la SNR del enfoque de micro-bobina introducido mostró un valor de 25 para la séptima de su volumen, incluso en un campo magnético algo menor. Con este nuevo enfoque de la alta sensibilidad de las células de yunque RMN uno puede perseguir muchas aplicaciones que prometen emocionante nueva visión de la física y la química de los materiales modernos. Sin embargo, como siempre, sensibilidad y resolución en última instancia limitan la aplicación de RMN, en particular, si uno está interesado en presiones mucho más altas que demandan Culet tamaños más pequeños. Entonces, uno tiene no sólo para optimizar el diseño de la célula con bobinas de RF, incluso más pequeños, sino también pensar en métodos para aumentar la polarización nuclear.

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high-sensitivity nuclear magnetic resonance at giga-pascal pressures: a new tool for probing electronic and chemical properties of condensed matter under extreme conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

La Figura 3 muestra cómo la célula completamente montado presión, el cableado y el montaje en una sonda de RMN típica parecen. A continuación, varios experimentos serán revisados ​​que debería permitir al lector para reunir un amplio panorama sobre los beneficios y limitaciones de la técnica introducida. <img alt="Figura 1" src="/files/ftp_upload/52243/52243fig1highres.jpg" /> Figura 1. diversos enfoques para RMN...

Watch this Scientific Journal Video about High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extr

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Alta sensibilidad de Resonancia Magnética Nuclear a presiones Giga-Pascal: Una nueva herramienta para sondear Propiedades electrónicas y químicas de la materia condensada en condiciones extremas

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

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Principles of Nuclear Magnetic Resonance

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11.5K vistas.  University of Leipzig. Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Video: High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

Síntesis y microdifracción a presiones y temperaturas extremas

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

Investigación

Ingeniería

Flame Experiments at the Advanced Light Source: New Insights into Soot Formation Processes

The following experimental protocols and the accompanying video are concerned with the flame experiments that are performed at the Chemical Dynamics Beamline of the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory1-4. This video demonstrates how the complex chemical structures of laboratory-based model flames are analyzed using flame-sampling mass spectrometry with tunable synchrotron-generated vacuum-ultraviolet (VUV) radiation. This experimental approach combines isomer-resolving capabilities with high sensitivity and a large dynamic range5,6. The first part of the video describes experiments involving burner-stabilized, reduced-pressure (20-80 mbar) laminar premixed flames. A small hydrocarbon fuel was used for the selected flame to demonstrate the general experimental approach. It is shown how species&#8217; profiles are acquired as a function of distance from the burner surface and how the tunability of the VUV photon energy is used advantageously to identify many combustion intermediates based on their ionization energies. For example, this technique has been used to study gas-phase aspects of the soot-formation processes, and the video shows how the resonance-stabilized radicals, such as C3H3, C3H5, and i-C4H5, are identified as important intermediates7. The work has been focused on soot formation processes, and, from the chemical point of view, this process is very intriguing because chemical structures containing millions of carbon atoms are assembled from a fuel molecule possessing only a few carbon atoms in just milliseconds. The second part of the video highlights a new experiment, in which an opposed-flow diffusion flame and synchrotron-based aerosol mass spectrometry are used to study the chemical composition of the combustion-generated soot particles4. The experimental results indicate that the widely accepted H-abstraction-C2H2-addition (HACA) mechanism is not the sole molecular growth process responsible for the formation of the observed large polycyclic aromatic hydrocarbons (PAHs).

Gas sampling from laboratory-scale flames with online analysis of all species by mass spectrometry is a powerful method to investigate the complex mixture of chemical compounds occurring during combustion processes. Coupled with tunable soft ionization via synchrotron-generated vacuum-ultraviolet radiation, this technique provides isomer-resolved information and potentially fragment-free mass spectra.

Los experimentos de la llama a la fuente de luz avanzada: nuevos conocimientos sobre los procesos de formación de hollín

The following experimental protocols and the accompanying video are concerned with the flame experiments that are performed at the Chemical Dynamics ...

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the &#8216;roll-over&#8217; cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

We describe the design and construction of an electrochemical cell for the examination of electrode materials using in situ neutron powder diffraction (NPD). We briefly comment on alternate in situ NPD cell designs and discuss methods for the analysis of the corresponding in situ NPD data produced using this cell.

In Situ de neutrones polvo Difracción Uso de baterías de litio-ion por encargo

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric ...

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample.

The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

Resonancia Raman Spectroscopy de nanocables de riesgo y otros sistemas 1D

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the ...

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

El uso de un de varios compartimentos dinámico sola enzima fantasma de Estudios de hiperpolarizados Agentes de Resonancia Magnética

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 &#176;C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. 
Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

In Situ La visualización del comportamiento de fases de muestras de aceite bajo condiciones de proceso de la refinería

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional experimental approaches, such as out-of-plane and in-plane tests, are not applicable to the determination of forming limits when heating and rapid cooling processes are introduced prior to forming for tests conducted under hot stamping conditions. A novel in-plane biaxial testing system was designed and used for the determination of forming limits of sheet metals at various strain paths, temperatures, and strain rates after heating and cooling processes in a resistance heating uniaxial testing machine. The core part of the biaxial testing system is a biaxial apparatus, which transfers a uniaxial force provided by the uniaxial testing machine to a biaxial force. One type of cruciform specimen was designed and verified for the formability test of aluminum alloy 6082 using the proposed biaxial testing system. The digital image correlation (DIC) system with a high-speed camera was used for taking strain measurements of a specimen during a deformation. The aim of proposing this biaxial testing system is to enable the forming limits of an alloy to be determined at various temperatures and strain rates under hot stamping conditions.

This protocol proposes a novel biaxial testing system used on a resistance heating uniaxial tensile test machine in order to determine the forming limit diagram (FLD) of sheet metals under hot stamping conditions.

Un nuevo aparato de ensayo biaxiales para la Determinación del límite de conformación bajo estampación en caliente Condiciones

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional ...

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve desired molecular orientation states in LC displays, the "static" surface property of LCs, so-called surface anchoring, has been intensively studied. As a rule of thumb, once the initial orientation of LCs is "locked" by specific surface treatments, such as rubbing or treatment with a specific alignment layer, it hardly changes with temperature. Here, we present a system exhibiting an orientational transition upon temperature variation, which conflicts with the consensus. Right on the transition, the bulk LC molecules experience the orientational rotation, with 90&#176; between the planar (P) orientation at high temperatures and the vertical (V) orientation at low temperatures in the first-order transitional manner. We have tracked thermodynamic surface anchoring behavior by means of polarizing optical microscopy (POM), dielectric spectroscopy (DS), high-resolution differential scanning calorimetry (HR-DSC), and grazing incidence X-ray diffraction (GI-XRD) and reached a plausible physical explanation: that the transition is triggered by a growth of surface wetting sheets, which impose the V orientation locally against the P orientation in the bulk. This landscape would provide a general link explaining how the equilibrium bulk orientation is affected by surface-localized orientation in many LC systems. In our characterization, POM and DS are advantageous by offering information on the spatial distribution of the orientation of LC molecules. HR-DSC gives information about the precise thermodynamic information on transitions, which cannot be addressed by conventional DSC instruments due to limited resolution. GI-XRD provides information on surface-specific molecular orientation and short-range orderings. The goal of this paper is to present a protocol for preparing a sample that exhibits the transition and to demonstrate how the thermodynamic structural variation, both in the bulk and on surfaces, can be analyzed through the abovementioned methods.

Here, we present a protocol to trigger an orientational transition of a liquid crystal in response to temperature. Methodologies are described for preparing a sample in order to observe the transition and the detailed transitional evolution.

Transición orientativa en un cristal líquido desencadenada por el crecimiento termodinámico de las húmedas interfaciales

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution. Several methods have been developed to overcome this shortcoming, including all-electronic time-resolved STM, which is used in this study to examine dopant dynamics in silicon with nanosecond resolution. The methods presented here are widely accessible and allow for local measurement of a wide variety of dynamics at the atomic scale. A novel time-resolved scanning tunneling spectroscopy technique is presented and used to efficiently search for dynamics.

We demonstrate an all-electronic method to observe nanosecond-resolved charge dynamics of dopant atoms in silicon with a scanning tunneling microscope.

Totalmente electrónico resuelto nanosegundo túnel microscopía: Facilitar la investigación de Dopant solo carga dinámica

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new ...

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape method or individual WS2 nanotubes by dispersing the suspension of WS2 nanotubes. The selected samples have been fabricated into devices by the use of the electron beam lithography and electrolyte is put on the devices. We have characterized the electronic properties of the devices under applying the gate voltage. In the small gate voltage region, ions in the electrolyte are accumulated on the surface of the samples which leads to the large electric potential drop and resultant electrostatic carrier doping at the interface. Ambipolar transfer curve has been observed in this electrostatic doping region. When the gate voltage is further increased, we met another drastic increase of source-drain current which implies that ions are intercalated into layers of WS2 and electrochemical carrier doping is realized. In such electrochemical doping region, superconductivity has been observed. The focused technique provides a powerful strategy for achieving the electric-filed-induced quantum phase transition.

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Here, we present a protocol to control the carrier number in solids by using the electrolyte.

Campo eléctrico Control de Estados electrónicos en WS2 nanodispositivos de electrolito que bloquean

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape ...