Los autores agradecen al Dr. Wes Gordon (ECBC) para el apoyo en el diseño del instrumento. Este trabajo representa el resultado acumulado por dos programas de investigación financiados por Eric Lowenstein y Michael Roberts (Agencia de Reducción de Amenazas de Defensa) bajo CA08MSB317 programa. Los informes técnicos citados en la presente memoria pueden obtenerse en <a href="http://www.dtic.mil">http://www.dtic.mil</a> .

1. pintura Condición Sustratos para el medio ambiente deseado <ol><li> Memorice la cámara ambiental para sustrato acondicionado a la temperatura especificada y humedad relativa (20 ° C, 50%). Asegúrese de que las condiciones del sustrato se mantiene constante desde la temperatura y el contenido de agua pueden influir de manera significativa las tasas de absorción en materiales. </li><li> Escudo 0,32 cm de espesor, 5,08 cm de radio discos de acero inoxidable con una superficie de 20,25 cm 2 con una capa de pintura (sistema de poliuretano alifático MIL-DTL-53039, un disolvente dispersable (SD) de recubrimiento 6) con un espesor total del recubrimiento ( imprimación y capa superior) de aproximadamente 100 micras. Coloque los sustratos (con número deseado de repeticiones) en bandejas de acero inoxidable con la superficie de prueba para estar expuestos a un agente químico hacia arriba. </li><li> Cubra los sustratos con placas de Petri. Colocar las bandejas que contienen los sustratos de ensayo en la cámara del medio ambiente por lo menos durante 60 min pero idealmente O / N, si es posible. </li></ol> 2. Contaminación de precondicionados Sustratos <ol><li> Equipo de protección personal tales como Don bata de laboratorio, gafas de seguridad y guantes. </li><li> PRECAUCIÓN: Obtenga los contaminantes químicos de almacenamiento en frío y permite vial contenedor primario se equilibre a RT. Los productos químicos utilizados en este protocolo son Química Analítica Agente Estándar Material de Referencia (CASARM, 98,0% de pureza) grado HD y CASARM (89,0% de alta pureza) grado VX (tanto en fase líquida). Obtener información de la pureza, ya sea análisis de espectroscopia de resonancia magnética nuclear cromatografía o gas / masa y mantener en archivo. NOTA: ATENCIÓN: La manipulación de agentes químicos de guerra sólo debe ser realizada por personal entrenado en una instalación aprobada utilizando precauciones de seguridad, de seguridad y de garantía aplicables. </li><li> PRECAUCIÓN: Coloque la herramienta de administración de agente con una punta de pipeta y configurar la herramienta para entregar una gota de agente (por ejemplo, 1 l). Destape lavial contaminante, y coloque la tapa en la superficie de la campana, los hilos hacia arriba. Recoge la pipeta, y baje lentamente la punta en la solución contaminante. Cargar la herramienta de administración del agente con el agente de conformidad con las instrucciones del fabricante. Coloque con cuidado la pipeta cargada sobre la superficie de trabajo capucha, y vuelva a tapar el vial contaminante. </li><li> PRECAUCIÓN: contaminar los sustratos de ensayo. <ol><li> Retire las bandejas que contienen los sustratos de prueba de la cámara ambiental. </li><li> Retire las placas de Petri de los substratos de ensayo, y situado en la superficie de la campana. Fotografiar digitalmente cada sustrato de prueba para registrar la apariencia de cada sustrato antes de la contaminación. </li><li> Recoge la pipeta cargada y entregar una sola gota (por ejemplo, 1 l) del agente sobre el primer sustrato de ensayo. Cubrir el material contaminado con una placa de Petri de poliestireno para minimizar la evaporación, mientras que la contaminación de sustratos adicionales. Repita el procedimiento para cada sustrato; recargar la punta de la pipeta (Step 2.3) según sea necesario. NOTA: Recoger muestras de confirmación de la pipeta antes y después de la administración de sustratos para el análisis mediante cromatografía para confirmar la entrega masiva de contaminantes. </li><li> Retire las placas de Petri de los sustratos de prueba y ajuste en la superficie de la campana. Fotografiar digitalmente cada sustrato de prueba para registrar las interacciones iniciales contaminante materiales. </li><li> Cubrir los sustratos de ensayo con las placas de Petri. </li><li> Coloque la bandeja de sustratos de nuevo en la cámara ambiental. </li></ol></li></ol> Interacción 3. Contaminante material Período Envejecimiento <ol><li> Antes de envejecimiento de las muestras, ventilar la cámara de alto vacío experimental de acero inoxidable para prepararlo para su uso en la Sección 4. </li><li> Permitir los sustratos contaminados a la edad en la cámara ambiental durante el tiempo especificado, que se puede variar basado en la dinámica de interacción química-material favorable al medio (por ejemplo, 60 min). </li><li> Retire los sustratos de la environmcámara ental y el lugar en la superficie de trabajo de la campana. Retire las placas de Petri de los substratos de ensayo y fotografiar digitalmente cada sustrato para registrar los post-envejecimiento interacciones de contaminantes material. </li><li> Haga doble contener las muestras de ensayo (por ejemplo, múltiples recipientes herméticos) y transferir a la campana trabajar con cámara de alto vacío. </li></ol> 4. Alto Vacío Medición Vapor Cámara de emisión La cámara de alto vacío es un pequeño recipiente de volumen bombeado por una bomba turbo molecular de arrastre y una bomba de diafragma de respaldo (Figura 2). Un espectrómetro de masas cuadrupolar está montado en un puerto que da directamente un soporte de sustrato de temperatura controlada y se utiliza para medir la evolución de gas en tiempo real a partir de sustratos contaminados bajo condiciones de alto vacío. Todos los detalles sobre las especificaciones y los materiales de la cámara de vacío se incluyen en la referencia 4. <ol><li> Asegúrese de que la cámara tiene una ventilación adecuada. </li><li> PRECAUCIÓN: Desempaquetar las muestras preparadas en la Sección 3, y retirar placa de Petri de los sustratos de prueba. Coloque sustrato una prueba en cada soporte del sustrato de temperatura controlada con unas pinzas de acero inoxidable. </li><li> Selle la cámara de vacío y comenzar la secuencia de bombeo. Realizar este paso de manera que la cámara está sellada en el momento edad especificada vacío (por ejemplo, 60 min) en relación a cuando estaba contaminado el sustrato. </li><li> Comenzar a grabar canales de fragmentos de masa seleccionada como una función del tiempo (medida directa de flujo de masa) identificado con masa específica por los valores de unidad de carga (m / z). Mida las especies específicas de gases de fondo, además de las fracciones de la masa primaria de las moléculas de interés (VX: m / z = 114; HD: m / z = 109) en tiempo real a &lt;0,25 Hz hasta que la presión parcial de contaminantes desciende por debajo de los límites de detección del espectrómetro de masas (10 - 8 Pa). </li><li> Recoge las curvas de emisión parala duración de la emisión de contaminantes del sustrato. </li><li> Detener la grabación curvas de emisión con el espectrómetro de masas una vez que el flujo de masa de contaminantes se ha reducido a la presión de la cámara de referencia. </li><li> Purgar la cámara de alto vacío a la presión atmosférica. </li></ol> 5. Post-tratamiento de Evaluación de Contaminantes restante total <ol><li> Abra el instrumento de alto vacío de la cámara de emisión de vapor (HVVEC) y retirar el sustrato de la cámara con unas pinzas de acero inoxidable. </li><li> Coloque el sustrato en un frasco de vidrio de extracción y añadir 20 ml de disolvente de extracción para el frasco (por ejemplo, alcohol isopropílico: VX; cloroformo: HD). Tapar el frasco y agitar el frasco tres veces. Dejar el sustrato en el disolvente de extracción durante 60 min. </li><li> Agitar el frasco tres veces más y luego destape el frasco. El uso de un desechable, pipeta de vidrio limpio, transferir aproximadamente 1 a 2 ml de disolvente de extracción en un vial de análisis para el análisis de gas o líquido a travéscromatografía 7 para medir la masa de contaminante retenido por los sustratos. </li></ol> 6. Análisis y Modelado de Datos <ol><li> Convertir los datos de espectrometría de masas en bruto (presión parcial derivado de corriente de iones medido) para flujo de masa del sustrato. Use una combinación de la fórmula Hertz-Knudsen para convertir la presión parcial de especies de gas detectados a incidente flujo de vapor en el detector e incluir un factor de escala que representa la zona contaminada sobre el sustrato desde el evento original de la contaminación. </li><li> Utilice métodos inversos (por ejemplo, el algoritmo de Levenberg-Marquardt) para determinar los valores constantes de concentración de saturación y de difusión (parámetros clave de transporte de masa) para el transporte de contaminantes a través de la capa de pintura. Compare el flujo de vapor de determinado experimentalmente a un flujo de vapor de predicho (una solución analítica a la segunda ley de Fick con condiciones de frontera apropiadas aplicadas (véase la ecuación 4 la referencia 4)). </li&gt; <li> Utilice los parámetros de transporte masivo para predecir los perfiles de concentración para el sistema-contaminante material. </li></ol>

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Los autores no tienen nada que revelar.

Parámetros de transporte de masa para HD y VX en la pintura se determinaron mediante el análisis inverso numérica de los datos de emisión de vapor. Con los parámetros calculados, era posible entonces producir mapas gradiente de concentración en función del tiempo para la distribución de contaminantes en la capa de pintura. Los resultados del análisis inversos demostraron que la solubilidad de HD en la pintura SD fue mayor que el VX, pero la difusividad fue de aproximadamente 5x inferior. Los resultados sugieren...

Los mecanismos de transporte de masa asociados con la contaminación de los materiales por los agentes de guerra química son impulsados ​​por una variedad de procesos incluyendo convolucionadas transiciones estado físico, interacciones químicas entre las especies móviles, y materiales de interfaces. Para desarrollar tecnologías eficaces de descontaminación, los procedimientos de descontaminación optimizados, y modelos de predicción, es vital que el proceso de contaminación se entiende bien, incluyendo el transporte de contaminantes en los materiales a través de la absorción y la emisión química subsecuente de nuevo en el medio ambiente. En consecuencia, es imperativo que se desarrollan enfoques que se pueden evaluar perfiles de concentración subsuperficial para pares de contaminantes de material como una función de las condiciones ambientales. A escala continua, el modelo basado en la física fue desarrollado para predecir la distribución de la concentración de agente de absorción en un sustrato contaminado. Parámetros de transporte de masas obtenidos experimentalmente permiten la predicción de tque el vapor de las emisiones de la contaminada mensaje material de descontaminación. La capacidad para predecir la distribución de la concentración de un material puede facilitar la evaluación de los riesgos potenciales de vapor y, a su vez, permitirá un diagnóstico preciso de los riesgos toxicológicos 1. Este enfoque permite una estimación de los parámetros específicos de par-contaminantes de material de transporte masivo como la concentración de la difusividad y la saturación que a su vez modelado permiso por otros escenarios y condiciones. En este estudio, hemos tratado a la contaminación en fase líquida de poliuretano, revestimientos de pintura con disolvente disperso con agentes de guerra química de bis (2-cloroetil) sulfuro (mostaza destilada, agente vesicante HD) y O etil S - [2 (diisopropilamino) etil] methylphosphonothioate (VX), un agente nervioso organofosforados. La metodología desarrollada caracteriza a los perfiles de desorción de gas a partir de materiales contaminados, incluyendo agentes de guerra química, como HD y VX, sinmuchas de las restricciones que dificultan el otro se acerca 2,3. Mediciones de espectrometría de masas de tiempo resuelto de la evolución de contaminantes a partir de sustratos contaminados permiten un modelo de transporte difusivo con análisis inverso para calcular los parámetros de transporte de masa para el contaminante en el material, incluyendo el perfil de concentración para el contaminante absorbido a partir del evento original de permeación. Con el establecimiento de una capacidad de predicción para delinear perfiles de concentración de contaminantes en los materiales en función de las condiciones ambientales viene la capacidad de evaluar los riesgos toxicológicos y en última instancia, desarrollar rutas para la descontaminación eficaz. En este trabajo, se presentan los detalles asociados con la preparación de muestras, incluyendo el trabajo con los contaminantes de agentes de guerra química, así como la recopilación de datos experimental de materiales contaminados y posterior modelado 4. Corridas experimentales se llevaron a cabo como descRibed en el documento de contaminantes químicos y fuente de descontaminante 5 y será discutido en la siguiente sección. Un diagrama de flujo para los pasos de preparación y análisis de la muestra en incluido en la Figura 1.

<table border="0" cellpadding="0" cellspacing="0" width="646">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Name of Material/Equipment</td>
			<td style="width:101px;">Company</td>
			<td style="width:97px;">Catalog Number</td>
			<td style="width:245px;">Comments/Description</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:203px;">Stainless Steel Tray</td>
			<td style="width:101px;">McMaster Carr</td>
			<td style="width:97px;">4189T1</td>
			<td style="width:245px;">13-5/8&#34; L x 9-3/4&#34; W, http://www.mcmaster.com/#stainless-steel-trays/=p8dcgp</td>
		</tr>
		<tr height="67">
			<td height="67" style="height:67px;width:203px;">MIL-DTL-53039 solvent-dispersible aliphatic polyurethane coating system</td>
			<td style="width:101px;"></td>
			<td style="width:97px;"></td>
			<td style="width:245px;">Substrates supplied by internal source</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:203px;">Environmental Chamber</td>
			<td style="width:101px;"></td>
			<td style="width:97px;"></td>
			<td style="width:245px;">Custom Design. Full details on vacuum chamber specifications and materials included in reference 4.</td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:203px;">bis(2-chloroethyl) sulfide</td>
			<td style="width:101px;">CASARM</td>
			<td style="width:97px;"></td>
			<td style="width:245px;">TOXIC</td>
		</tr>
		<tr height="65">
			<td height="65" style="height:65px;width:203px;">O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate</td>
			<td style="width:101px;">CASARM</td>
			<td style="width:97px;"></td>
			<td style="width:245px;">TOXIC</td>
		</tr>
		<tr height="49">
			<td height="49" style="height:49px;width:203px;">Pipetter</td>
			<td style="width:101px;">Fisher Scientific</td>
			<td>22260201</td>
			<td style="width:245px;">Range of 1.0 &#181;L to 10 mL</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Pipetter Tips</td>
			<td style="width:101px;">Fisher Scientific</td>
			<td style="width:97px;">13-683-709</td>
			<td style="width:245px;">0.1 mL Volume</td>
		</tr>
		<tr height="44">
			<td height="44" style="height:44px;width:203px;">Stainless Steel High Vacuum Experimental Chamber</td>
			<td style="width:101px;"></td>
			<td style="width:97px;"></td>
			<td style="width:245px;">Custom Design</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Quadrupole Mass Spectrometer</td>
			<td style="width:101px;">ExTorr</td>
			<td style="width:97px;">RGA300</td>
			<td style="width:245px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Stainless Steel Tweezers</td>
			<td style="width:101px;">McMaster Carr</td>
			<td style="width:97px;">5516A15</td>
			<td style="width:245px;">Any stainless steel tweezers are appropriate.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:203px;">Glass Extraction Jar</td>
			<td style="width:101px;">Scientific Specialties</td>
			<td style="width:97px;">170808</td>
			<td style="width:245px;">Jar fits a ~5 cm diameter substrate.&#160; Different glass jars with teflon lined lids are appropriate for different sized substrates.</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:203px;">Chloroform</td>
			<td style="width:101px;">Sigma-Aldrich</td>
			<td style="width:97px;">650498</td>
			<td style="width:245px;">HARMFUL.&#160; The extraction solvent for HD may change depending on the analytical method.</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:203px;">Isopropanol</td>
			<td style="width:101px;">Sigma-Aldrich</td>
			<td style="width:97px;">650447</td>
			<td style="width:245px;">HARMFUL.&#160; The extraction solvent for VX may change depending on the analytical method.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Pasteur Pipette</td>
			<td style="width:101px;">VWR</td>
			<td style="width:97px;">14673-010</td>
			<td style="width:245px;">size= 5 3/4&#34;</td>
		</tr>
	</tbody>
</table>

an inverse analysis approach to the characterization of chemical transport in paints

La capacidad para caracterizar directamente el transporte química y las interacciones que se producen dentro de un material (es decir, la dinámica del subsuelo) es un componente vital en la comprensión de transporte de masa de contaminantes y la capacidad para descontaminar materiales. Si se contamina un material, con el tiempo, el transporte de productos químicos altamente tóxicos (tales como especies de agente de guerra química) fuera del material puede dar lugar a la exposición al vapor o transferir a la piel, lo que puede resultar en una exposición percutánea al personal que interactúan con el material. Debido a la alta toxicidad de los agentes de guerra química, la liberación de cantidades de trazas químicas es de gran preocupación. Características de distribución de la concentración del subsuelo Cartografía y transporte de agentes absorbidos permite a los riesgos de exposición que deben evaluarse en condiciones no probados. Además, estas herramientas se pueden utilizar para caracterizar la dinámica de reacción del subsuelo para diseñar en última instancia, la mejora de los procedimientos de descontaminación o descontaminantes. To lograr este objetivo, una masa análisis de enfoque de modelado transporte inverso fue desarrollado que utiliza medidas de espectroscopia de masas con resolución temporal de emisión de vapor de recubrimientos de pintura contaminadas como el parámetro de entrada para el cálculo de los perfiles de concentración del subsuelo. Los detalles figuran en la preparación de la muestra, incluyendo contaminantes y manejo de materiales, la aplicación de la espectrometría de masas para la medición de vapor contaminante emitida, y la aplicación de análisis inverso utilizando un modelo de difusión basado en la física para determinar las propiedades de transporte de agentes de guerra química en directo incluida el agua destilada mostaza (HD) y el agente nervioso VX.

El panel superior de la Figura 3 muestra ejemplos de el flujo de masa calculada de VX y HD a partir de sustratos pintados SD basadas en la espectrometría de masas de tiempo resuelto para los principales fragmentos de masa de VX y HD (-masa-carga relación, m / z = 114 y 109, respectivamente). Un espectrómetro de masas cuadrupolo tiene tres componentes principales: un ionizador, un analizador de masas o de filtro, y un detector de carga. Especies de gas se ionizan mediante ionización...

Watch this Scientific Journal Video about An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints at JoVE.com

An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

En este trabajo se presenta un procedimiento para cuantificar los parámetros de transporte masivo de productos químicos en diversos materiales. Este proceso implica el empleo de un modelo de difusión basado inversa-análisis a vapor perfiles de emisión registrados por tiempo real, espectrometría de masas en alto vacío.

Un enfoque de análisis inverso a la caracterización de Transporte de Productos Químicos en Pinturas

The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in ...

an-inverse-analysis-approach-to-characterization-chemical-transport

Research

JoVE Journal

Chemistry

8.3K vistas.  U.S. Army Edgewood Chemical Biological Center.  En este trabajo se presenta un procedimiento para cuantificar los parámetros de transporte masivo de productos químicos en diversos materiales. Este proceso implica el empleo de un modelo de difusión basado inversa-análisis a vapor perfiles de emisión registrados por tiempo real, espectrometría de masas en alto vacío. 

Video: An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development

The involvement of free radicals in life sciences has constantly increased with time and has been connected to several physiological and pathological processes. This subject embraces diverse scientific areas, spanning from physical, biological and bioorganic chemistry to biology and medicine, with applications to the amelioration of quality of life, health and aging. Multidisciplinary skills are required for the full investigation of the many facets of radical processes in the biological environment and chemical knowledge plays a crucial role in unveiling basic processes and mechanisms. We developed a chemical biology approach able to connect free radical chemical reactivity with biological processes, providing information on the mechanistic pathways and products. The core of this approach is the design of biomimetic models to study biomolecule behavior (lipids, nucleic acids and proteins) in aqueous systems, obtaining insights of the reaction pathways as well as building up molecular libraries of the free radical reaction products. This context can be successfully used for biomarker discovery and examples are provided with two classes of compounds: mono-trans isomers of cholesteryl esters, which are synthesized and used as references for detection in human plasma, and purine 5',8-cyclo-2'-deoxyribonucleosides, prepared and used as reference in the protocol for detection of such lesions in DNA samples, after ionizing radiations or obtained from different health conditions.

Radical-based biomimetic chemistry has been applied to building-up libraries necessary for biomarker development.

Radicales Libres en Biología Química: del comportamiento químico al desarrollo de biomarcadores

The involvement of free radicals in life sciences has constantly increased with time and has been connected to several physiological and pathological ...

Investigación

Química

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS can be subdivided into three domains: the distal O-polysaccharide, a core oligosaccharide, and the lipid A domain consisting of a lipid A molecular species and 3-deoxy-D-manno-oct-2-ulosonic acid residues (Kdo). The lipid A domain is the only component essential for bacterial cell survival. Following its synthesis, lipid A is chemically modified in response to environmental stresses such as pH or temperature, to promote resistance to antibiotic compounds, and to evade recognition by mediators of the host innate immune response. The following protocol details the small- and large-scale isolation of lipid A from gram-negative bacteria. Isolated material is then chemically characterized by thin layer chromatography (TLC) or mass-spectrometry (MS). In addition to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS, we also describe tandem MS protocols for analyzing lipid A molecular species using electrospray ionization (ESI) coupled to collision induced dissociation (CID) and newly employed ultraviolet photodissociation (UVPD) methods. Our MS protocols allow for unequivocal determination of chemical structure, paramount to characterization of lipid A molecules that contain unique or novel chemical modifications. We also describe the radioisotopic labeling, and subsequent isolation, of lipid A from bacterial cells for analysis by TLC. Relative to MS-based protocols, TLC provides a more economical and rapid characterization method, but cannot be used to unambiguously assign lipid A chemical structures without the use of standards of known chemical structure. Over the last two decades isolation and characterization of lipid A has led to numerous exciting discoveries that have improved our understanding of the physiology of gram-negative bacteria, mechanisms of antibiotic resistance, the human innate immune response, and have provided many new targets in the development of antibacterial compounds.

Isolation and characterization of the lipid A domain of lipopolysaccharide (LPS) from gram-negative bacteria provides insight into cell surface based mechanisms of antibiotic resistance, bacterial survival and fitness, and how chemically diverse lipid A molecular species differentially modulate host innate immune responses.

Aislamiento y Caracterización química del lípido A de bacterias gram-negativas

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS ...

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at &#60;60 &#176;C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics.

We present the synthesis of the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x, x~2) via low temperature chemical vapor deposition (CVD). This optimized recipe yields an increase in Curie temperature from 400 K to over 600 K and a dramatic improvement in magnetic resonance properties.

Deposición de vapor químico de un imán Orgánica, vanadio tetracianoetileno

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Síntesis y caracterización de supramoleculares Coloides

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Glycan Node Analysis: A Bottom-up Approach to Glycomics

Synthesized in a non-template-driven process by enzymes called glycosyltransferases, glycans are key players in various significant intra- and extracellular events. Many pathological conditions, notably cancer, affect gene expression, which can in turn deregulate the relative abundance and activity levels of glycoside hydrolase and glycosyltransferase enzymes. Unique aberrant whole glycans resulting from deregulated glycosyltransferase(s) are often present in trace quantities within complex biofluids, making their detection difficult and sometimes stochastic. However, with proper sample preparation, one of the oldest forms of mass spectrometry (gas chromatography-mass spectrometry, GC-MS) can routinely detect the collection of branch-point and linkage-specific monosaccharides ("glycan nodes") present in complex biofluids. Complementary to traditional top-down glycomics techniques, the approach discussed herein involves the collection and condensation of each constituent glycan node in a sample into a single independent analytical signal, which provides detailed structural and quantitative information about changes to the glycome as a whole and reveals potentially deregulated glycosyltransferases. Improvements to the permethylation and subsequent liquid/liquid extraction stages provided herein enhance reproducibility and overall yield by facilitating minimal exposure of permethylated glycans to alkaline aqueous conditions. Modifications to the acetylation stage further increase the extent of reaction and overall yield. Despite their reproducibility, the overall yields of N-acetylhexosamine (HexNAc) partially permethylated alditol acetates (PMAAs) are shown to be inherently lower than their expected theoretical value relative to hexose PMAAs. Calculating the ratio of the area under the extracted ion chromatogram (XIC) for each individual hexose PMAA (or HexNAc PMAA) to the sum of such XIC areas for all hexoses (or HexNAcs) provides a new normalization method that facilitates relative quantification of individual glycan nodes in a sample. Although presently constrained in terms of its absolute limits of detection, this method expedites the analysis of clinical biofluids and shows considerable promise as a complementary approach to traditional top-down glycomics.

This article presents an enhanced form of a novel bottom-up glycomics technique designed to analyze the pooled compositional profile of glycans in unfractionated biofluids through the chemical breakdown of glycans into their constituent linkage-specific monosaccharides for detection by GC-MS. Potential applications include early detection of cancer and other glycan-affective disorders.

El análisis de glicanos Nodo: un enfoque de abajo hacia arriba para Glicómica

Synthesized in a non-template-driven process by enzymes called glycosyltransferases, glycans are key players in various significant intra- and ...

Microfluidic Pneumatic Cages: A Novel Approach for In-chip Crystal Trapping, Manipulation and Controlled Chemical Treatment

The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. Herein, we introduce a microfluidic-based technology, employing a double-layer microfluidic device, which can trap and localize in situ and ex situ synthesized structures on microfluidic channel surfaces. Crucially, we show how such a device can be used to conduct controlled chemical reactions onto on-chip trapped structures and we demonstrate how the synthetic pathway of a crystalline molecular material and its positioning inside a microfluidic channel can be precisely modified with this technology. This approach provides new opportunities for the controlled assembly of structures on surface and for their subsequent treatment.

Herein, we describe the fabrication and operation of a double-layer microfluidic system made of polydimethylsiloxane (PDMS). We demonstrate the potential of this device for trapping, directing the coordination pathway of a crystalline molecular material and controlling chemical reactions onto on-chip trapped structures.

Jaulas neumáticas de microfluidos: Un nuevo enfoque para In-chip de cristal reventado, manipulación y tratamiento químico controlado

The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. ...

Original Experimental Approach for Assessing Transport Fuel Stability

The study of fuel oxidation stability is an important issue for the development of future fuels. Diesel and kerosene fuel systems have undergone several technological changes to fulfill environmental and economic requirements. These developments have resulted in increasingly severe operating conditions whose suitability for conventional and alternative fuels needs to be addressed. For example, fatty acid methyl esters (FAMEs) introduced as biodiesel are more prone to oxidation and may lead to deposit formation. Although several methods exist to evaluate fuel stability (induction period, peroxides, acids, and insolubles), no technique allows one to monitor the real-time oxidation mechanism and to measure the formation of oxidation intermediates that may lead to deposit formation. In this article, we developed an advanced oxidation procedure (AOP) based on two existing reactors. This procedure allows the simulation of different oxidation conditions and the monitoring of the oxidation progress by the means of macroscopic parameters, such as total acid number (TAN) and advanced analytical methods like gas chromatography coupled to mass spectrometry (GC-MS) and Fourier Transform Infrared - Attenuated Total Reflection (FTIR-ATR). We successfully applied AOP to gain an in-depth understanding of the oxidation kinetics of a model molecule (methyl oleate) and commercial diesel and biodiesel fuels. These developments represent a key strategy for fuel quality monitoring during logistics and on-board utilization.

Oxidation stability of transport fuels has become a concern for future fuel development. This work presents an original methodology developed by IFP Energies Nouvelles for assessing fuel stability using two different reactors. This methodology was successfully applied to gain an in-depth understanding of the oxidation kinetics and pathways of model molecules and commercial fuels.

Enfoque experimental original para evaluar el transporte de combustible Estabilidad

The study of fuel oxidation stability is an important issue for the development of future fuels. Diesel and kerosene fuel systems have undergone several ...

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic acids containing three to six carbons), such as malate and citrate, are critical to the proper functioning of many biological systems, where they function in cellular respiration and can serve as indicators of cell health. In foods, organic acid content can have significant impact on taste, with increased SCCA levels resulting in a sour or &#34;acid&#34; taste. Because of this, methods for the rapid analysis of organic acid levels are of particular interest to the food and beverage industries. Unfortunately, however, most methods used for SCCA quantification are dependent on time-consuming protocols requiring the derivatization of samples with hazardous reagents, followed by costly chromatographic and/or mass spectrometric analyses. This method details an alternate method for the detection and quantification of organic acids from plant material and food samples using free zonal capillary electrophoresis (CZE), sometimes simply referred to as capillary electrophoresis (CE). CZE provides a cost-effective method for measuring SCCAs with a low limit of detection (0.005 mg/ml). This article details the extraction and quantification of SCCAs from plant samples. While the method provided focuses on measurement of SCCAs from coffee beans, the method provided can be applied to multiple plant-based food materials.

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds

This article presents a method for the detection and quantification of organic acids from plant material using free zonal capillary electrophoresis. An example of the potential application of this method, determining the effects of a secondary fermentation on organic acid levels in coffee seeds, is provided.

Utilizando electroforesis capilar para cuantificar ácidos orgánicos a partir de Tejidos Vegetales: Un caso de prueba del examen<em&gt; Coffea arabica</em&gt; Semillas

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic ...

Characterizing Electron Transport through Living Biofilms

Here we demonstrate the method of electrochemical gating used to characterize electrical conductivity of electrode-grown microbial biofilms under physiologically relevant conditions.1 These measurements are performed on living biofilms in aqueous medium using source and drain electrodes patterned on a glass surface in a specialized configuration referred to as an interdigitated electrode (IDA) array. A biofilm is grown that extends across the gap connecting the source and drain. Potentials are applied to the electrodes (ES and ED) generating a source-drain current (ISD) through the biofilm between the electrodes. The dependency of electrical conductivity on gate potential (the average of the source and drain potentials, EG = [ED + ES]/2) is determined by systematically changing the gate potential and measuring the resulting source-drain current. The dependency of conductivity on gate potential provides mechanistic information about the extracellular electron transport process underlying the electrical conductivity of the specific biofilm under investigation. The electrochemical gating measurement method described here is based directly on that used by M. S. Wrighton2,3 and colleagues and R. W. Murray4,5,6 and colleagues in the 1980&#39;s to investigate thin film conductive polymers.

A protocol for measuring electrical conductivity of living microbial biofilms under physiologically relevant conditions is presented.

Caracterizar el transporte de electrones a través de Biofilms de vida

Here we demonstrate the method of electrochemical gating used to characterize electrical conductivity of electrode-grown microbial biofilms under ...

Pretargeted Radioimmunotherapy Based on the Inverse Electron Demand Diels-Alder Reaction

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can result in high radiation doses to healthy tissues. Perhaps not surprisingly, several different strategies have been developed to circumvent this troubling limitation. One of the most promising of these approaches is pretargeted radioimmunotherapy (PRIT). PRIT is predicated on decoupling the radionuclide from the immunoglobulin, injecting them separately, and then allowing them to combine in vivo at the target tissue. This approach harnesses the exceptional tumor-targeting properties of antibodies while skirting their pharmacokinetic drawbacks, thereby lowering radiation doses to non-target tissues and facilitating the use of radionuclides with half-lives that are considered too short for use in traditional radioimmunoconjugates. Over the last five years, our laboratory and others have developed an approach to in vivo pretargeting based on the inverse electron-demand Diels-Alder (IEDDA) reaction between trans-cyclooctene (TCO) and tetrazine (Tz). This strategy has been successfully applied to pretargeted positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a variety of antibody-antigen systems. In a pair of recent publications, we have demonstrated the efficacy of IEDDA-based PRIT in murine models of pancreatic ductal adenocarcinoma and colorectal carcinoma. In this protocol, we describe protocols for PRIT using a 177Lu-DOTA-labeled tetrazine radioligand ([177Lu]Lu-DOTA-PEG7-Tz) and a TCO-modified variant of the colorectal cancer targeting huA33 antibody (huA33-TCO). More specifically, we will describe the construction of huA33-TCO, the synthesis and radiolabeling of [177Lu]Lu-DOTA-PEG7-Tz, and the performance of in vivo biodistribution and longitudinal therapy studies in murine models of colorectal carcinoma.

This protocol describes the synthesis and characterization of a trans-cyclooctene (TCO)-modified antibody and a 177Lu-labeled tetrazine (Tz) radioligand for pretargeted radioimmunotherapy (PRIT). In addition, it details the use of these two constructs for in vivo biodistribution and longitudinal therapy studies in a murine model of colorectal cancer.

Radioinmunoterapia pretargeted basada en la reacción de Diels-Alder de demanda electrónica inversa

While radioimmunotherapy (RIT) is a promising approach for the treatment of cancer, the long pharmacokinetic half-life of radiolabeled antibodies can ...