bluuebunny/crossref_metadata_2025 huggingface dataset:
Métodos para reducir la contaminación por mercurio en la pequeña minería del oro
Authors: Pantoja-Timarán F. , Álvarez-Rodríguez R. , Rodríguez-Avelló A. S.
Published: February 2010

La utilización del mercurio para la extracción de oro es, todavía, una práctica habitual en las pequeñas instalaciones mineras, especialmente en los países en desarrollo, debido a la baja inversión requerida y a la facilidad de operación. Pero la falta de medidas de seguridad hace inevitable una importante contaminación de los rios, de los suelos y también de los trabajadores. Se han realizado algunos avances, sobre el terreno, como en lo relativo a la eliminación de mercurio de la amalgama que se realizaba al aire y ahora se utilizan sencillas y baratas retortas de hierro que disminuyen mucho la emisión de vapores de mercurio a la atmósfera, pero sigue habiendo muchas pérdidas de mercurio en los residuos o estériles del proceso de amalgamación que es, fundamentalmente, casi todo el peso de mineral tratado. Para la reducción de estas pérdidas de mercurio en los estériles del proceso se ha realizado esta investigación, utilizando procesos muy baratos, asequibles a los mineros aislados, demostrando que es posible lograr una disminución muy importante de dichas pérdidas y de la contaminación consiguiente. Para ello se han utilizado técnicas de lavado con detergentes alcalinos de la mena y de purificación electrólitica del mercurio con un sencillo y barato equipo que puede ser construido por los propios mineros, así como la demostración de que un sencillo ensayo de control de los tiempos de amalgamación y proporción de mercurio utilizado puede disminuir también las pérdidas, conjuntamente con un aumento de la recuperación de oro. De esta forma, es posible alcanzar pérdidas totales de mercurio de 2,4 g por cada 100 g de oro producido para menas muy ricas y recuperación de oro del 94 % (La Bruja), y de 8,6 g de pérdidas de mercurio por 100 g de oro producido en menas tipo medio de la zona y recuperación de oro del 92 % (La Gruesa), que son del orden de 20 a 100 veces menores que las pérdidas corrientes de los pequeños mineros, reflejadas en la bibliografía. La introducción de una fase previa de concentración gravimétrica en mesas de sacudidas disminuye hasta un 70 % la cantidad de material a amalgamar y, por lo tanto, los residuos sólidos contaminados, mejorando en el caso de la mena rica utilizada la recuperación de oro y empeorándola en el caso de la mena menos rica, en la que con un tratamiento combinado de concentración en mesas y flotación de los estériles de mesa se logran recuperaciones mejores que con la amalgamación directa pero,, en este caso, especialmente por la flotación, el proceso no será de uso general entre los pequeños mineros por su mayor dificultad de utilización y de coste de equipamiento.
Comportamiento frente al desgaste y fricción de aceros empleados en líneas de manutención aérea ensayados con y sin lubricación
Authors: Castro Regal G. , Fernández-Vicente A. , Martínez M. A.
Published: February 2010

Se ha evaluado el comportamiento frente a fricción y el desgaste de distintas calidades de acero ensayadas bajo condiciones de lubricación y sin lubricación. Las calidades de acero seleccionadas son las que normalmente se emplean en los sistemas de manutención aérea de numerosos procesos de producción, como la fabricación de automóviles. Se han realizado ensayos de desgaste tipo punzón-disco mediante un punzón de acero de calidad100Cr6, empleado en los carros que circulan por las líneas de manutención aérea. Se ha observado que el valor del coeficiente de fricción obtenido bajo condiciones de lubricaciones, aproximadamente, tres veces menor que el obtenido sin lubricación. Por otro lado, el mecanismo que controla el proceso de desgaste de los aceros ensayados con lubricación es un mecanismo de desgaste abrasivo y los valores de desgaste obtenidos son prácticamente despreciables. El desgaste de los aceros ensayados sin lubricación se produjo por combinación de dos mecanismos de desgaste: abrasión y adhesión.
Algunas influencias de la composición química sobre la viscosidad de las escorias sintéticas usadas en la colada continua del acero
Authors: Heput T. , Ardelean E. , Kiss I.
Published: February 2010

La calidad de productos semiacabados de la colada continua está influenciada, en gran parte, por el proceso de lubricación de la matriz que, a su vez, está influenciado por la viscosidad de escoria que resulta de la colada de polvos de fundición. Este trabajo analiza la influencia de composición química sobre la viscosidad de la escoria. La investigación ha tenido como meta establecer unas correlaciones entre la viscosidad dinámica y la composición química de la escoria. Para la composición química se han escogido como factores variables (componentes representativos) el contenido de CaO, MgO, Al2O3, SiO2 (los dos últimos expresados por la razón Al2O3/SiO2). Los ensayos sobre la viscosidad se han realizado sobre escoria a temperaturas de 1.350 °C. El análisis de los datos se ha efectuado en los laboratorios MATLAB y se han obtenido cuatro correlaciones múltiples. Los resultados se presentan tanto en forma analítica como gráfica. La utilización" de las relaciones obtenidas permite determinar la viscosidad de las escorias con un error matemático y la utilización de las correlaciones gráficas permite establecer el área de variación (los límites) de la viscosidad, para los componentes representativos.
Tensiones residuales generadas en acero F-522 por distintos tipos de mecanizado
Authors: García-Navas V. , Ferreres I. , Marañón J. A. , García-Rosales C. , Gil-Sevillano J.
Published: February 2010

Las operaciones de mecanizado generan deformación plástica y calor en la zona próxima a la superficie de la pieza mecanizada, dando lugar a tensiones residuales. Dependiendo de su magnitud y signo, estas tensiones pueden ser perjudiciales o beneficiosas para la vida en servicio de la pieza. El estado final de tensiones depende del proceso de mecanizado aplicado, así como de los parámetros del mismo. Por tanto, el establecimiento de unas pautas de mecanizado adecuadas requiere una medida precisa de las tensiones residuales generadas, tanto en la superficie, como en el interior del material. En este trabajo se han medido, mediante difracción de rayos-X, las tensiones residuales en un acero F-522 templado y revenido, generadas por dos procesos de torneado (torneado duro convencional y torneado duro asistido por láser) y dos procesos de rectificado (de afino y de producción). Asimismo, se ha estudiado la evolución a lo largo de la profundidad de la fracción volumétrica de austenita retenida, de la microestructura y de nanodureza con el objetivo de relacionar estos resultados con los estados de tensiones obtenidos para cada mecanizado. Se ha observado que el torneado genera fuertes tensiones de tracción en la superficie y el rectificado tensiones de compresión. Inmediatamente, bajo la superficie, el rectificado genera tensiones ligeramente tractivas o nulas, mientras que el torneado genera tensiones fuertemente compresivas. Estos resultados indican que el proceso óptimo de mecanizado (prescindiendo de consideraciones económicas) sería aquel que combinase un torneado duro con un ligero rectificado final
Estudio cinético de la eliminación de Cu (II) de soluciones acuosas mediante cascarilla de laminación
Authors: Martín M. I. , López F. A. , Alguacil F. J.
Published: February 2010

La eliminación de Cu (II) de soluciones acuosas, mediante cascarilla de laminación, ocurre por un proceso de oxidación-reducción o cementación de los iones Cu2+ en solución acuosa sobre el hierro metálico (Fe0) contenido en la cascarilla. La cinética de la cementación de cobre sobre hierro fue evaluada para diferentes temperaturas, concentraciones iniciales de cobre y relaciones sólido/líquido. El proceso de eliminación de cobre mediante cascarilla de laminación responde a una cinética de primer orden. El valor de la constante de velocidad (k) varía con la temperatura y con la concentración inicial del catión en solución, a bajas temperaturas. A altas temperaturas, el valor de k permanece, prácticamente, constante. El valor de la relación sólido/líquido también afecta el valor de la constante de velocidad.
Caracterización por microscopía electrónica de partículas Cu-Cr3C2 aleadas mecánicamente y consolidadas en caliente
Authors: López M. , Camurri C. , Vergara V. , Jiménez J. A.
Published: February 2010

Se obtuvieron aleaciones compuestas de Cu-Cr3C2, aleadas mecánicamente, para estudiar futuras aplicaciones en componentes eléctricos. A altas temperaturas, las aleaciones de base cobre reforzadas por dispersión, son atractivas por su excelente conductividad térmica y eléctrica, propiedades mecánicas y estabilidad microstructural. En este estudio, mezclas de polvo de cobre puro con un 2 % en vol. de Cr3C2, obtenidas mediante molienda en un molino de bolas planetario de alta energía, durante 4, 6, 10, 12 y 15 h, se compactaron isostáticamente en caliente a 1.073 K durante 2 h con una presión de 100 MPa en argón, para obtener un material con una microestructura fina. Las aleaciones de Cu-Cr3C2 se estudiaron mediante microscopía electrónica de barrido MEB y de transmisión MET, además de microsonda electrónica. También, se caracterizaron las propiedades mecánicas y la conductividad eléctrica, obteniéndose valores de 500 MPa y 50 % IACS, respectivamente. Las cerámicas de Cr3C2 presentan una buena estabilidad durante la compactación en caliente. Se observó la precipitación de partículas de tamaño nanométrico en la matriz de cobre, consistentes en carburos de hierro precipitados en ella, lo que contribuye al reforzamiento adicional de estas aleaciones. Los oxicarburos de Fe-Cr, formados en la interfase entre partículas de Cr3C2 y la matriz de cobre provocan la baja ductilidad de estas aleaciones. Estas partículas son atribuibles a impurezas y contaminación generada durante el proceso de molienda.
Desarrollo y caracterización del material compuesto de base cobre reforzado con cerámicas intermetálicas de TiB2
Authors: López M. , Camurri C. , Corredor D. , Jiménez J. A.
Published: February 2010

En este trabajo se han caracterizado las propiedades mecánicas y eléctricas de materiales compuestos de base cobre reforzados mediante la dispersión de partículas de TiB2. Las mezclas cobre-cerámica, se obtuvieron por molienda mecánica de polvos de cobre y TiB2, en un molino planetario, durante 12 y 36 h bajo atmósfera de argón. El polvo resultante se compactó bajo una presión uniaxial 90 MPa durante 2 h a 923 K. Algunos de los compactos resultantes se laminaron a una temperatura comprendida entre 1073 y 1023 K hasta alcanzarse una reducción del 20 %. Comparando las propiedades de los materiales, tras este procesado termomecánico, con las propiedades de los materiales compactados uniaxialmente, se encontró que la laminación en caliente aumenta la conductividad eléctrica, pero da lugar a una disminución del valor de la dureza y la ductilidad.
Estabilidad de la aleación Cu - 2,5 % Li en el rango 298 a 673 K
Authors: Ortiz M. , Carrasco C. , Díaz P. , Peñaloza A. , Wörner C.
Published: February 2010

Contribuyendo a la escasa información que se encuentra actualmente en la literatura científica acerca de las aleaciones Cu-Li, este trabajo informa la evolución de la aleaciónCu-2,5 % Li en peso, en función de la temperatura. La aleación se obtiene en forma de polvo, en un proceso de electrodepósito desde sales fundidas. Se analizan muestras en polvo, pastillas compactadas a temperatura ambiente y los cátodos de cobre utilizados en el proceso. Las muestras son sometidas a tratamientos térmicos en el rango de 293 a 673 K, por diferentes periodos de tiempo y caracterizadas mediante difracción de rayos X y determinación del contenido de litio por absorción atómica. El análisis de los resultados muestra una descomposición de la aleación conforme aumenta la temperatura, con una pérdida de litio hacia la superficie de las muestras, donde este elemento reacciona fácilmente con el ambiente, formando compuestos solubles en agua
Estudio del desgaste de aceros rápidos pulvimetalúrgicos M3/2 reforzados con carburo de niobio mediante el ensayo pin-on-disk
Authors: Candela N. , López A. , Ruano O. A. , Jiménez J. A.
Published: February 2010

En este trabajo se han preparado materiales compuestos de acero rápido M3/2 reforzado con un 5, un 10 y un 15 % en volumen de carburos de niobio con el objeto de mejorar sus propiedades mecánicas y resistencia al desgaste. La fabricación de los distintos materiales compuestos se realizó mediante molienda mecánica de polvo de acero rápido y carburo en un molino de alta energía, y compactación isostática en caliente. El comportamiento al desgaste se determinó a través de ensayos pin-on-disk. El material de partida presenta una microestructura con un tamaño de grano de pocas mieras y pequeños carburos MC y M6C homogéneamente dispersos en su interior. En el caso de los materiales reforzados, las partículas reforzantes de carburo se sitúan mayoritariamente sobre la superficie de las partículas originales de polvo de acero. El comportamiento al desgaste se evaluó a partir del coeficiente de fricción y de desgaste y de la pérdida de volumen eliminado en el ensayo. La incorporación de carburo de niobio mejora las propiedades al desgaste del acero rápido, tanto en el estado martensítico como de revenido, produciéndose una disminución del volumen de material eliminado y del coeficiente de desgaste a medida que se incrementa la fracción de volumen de partículas de NbC
Revisión de algoritmos para modelización de equilibrios de distribución de metales en procesos de extracción líquido-líquido
Authors: Lozano L. J. , Alguacil F. J. , Alonso M. , Godínez C.
Published: February 2010

El trabajo presenta las líneas generales a considerar para la estimación del equilibrio de distribución de metales en procesos de extracción líquido-líquido, según dos métodos: algoritmo clásico de mínimos cuadrados y redes neuronales artificiales. El objetivo del procedimiento, en el caso del método estadístico, es encontrar los valores de las constantes de equilibrio (Kj para las reacciones involucradas en la extracción del metal, que minimizan las diferencias entre el coeficiente de distribución experimental y el coeficiente de distribución teórico, de acuerdo al mecanismo propuesto. En la primera parte del artículo se comparan los resultados obtenidos a partir de los algoritmos usados más habitualmente en la bibliografía, con los datos obtenidos mediante el algoritmo previamente descrito. En la segunda parte, se presentan las características fundamentales para aplicar una red neuronal sencilla con algoritmo back-propagation y los resultados obtenidos se comparan con los de los métodos clásicos
Lixiviación de concentrados de cobre utilizando NaCI y el cobre soluble aportado por el propio concentrado
Authors: Herreros O. , Bernal N. , Quiroz R. , Fuentes G. , Viñals J.
Published: February 2010

Se ha estudiado la lixiviación de concentrados de cobre mediante cloro-complejos cúpricos, generados in situ por la reacción entre el Cu(II) procedente del cobre soluble del concentrado y cloruro de sodio en medio ácido. Se utilizaron concentrados de cobre provenientes de faenas mineras de Antofagasta, Chile. Se ha efectuado una caracterización química y mineralógica de los concentrados originales. Se ha estudiado el efecto de las siguientes variables, durante la lixiviación: concentración de cloruro, concentración de cobre soluble, tiempo de lixiviación, porcentaje de sólidos y temperatura. Se han caracterizado los residuos sólidos por DRX y microscopia electrónica. Los resultados experimentales indican que es posible obtener disoluciones con contenidos de cobre entre 15 y 35 g/l y de 2 a 5 g/l de acidez libre, con características adecuadas para entrar a la etapa de extracción por solventes. El procedimiento utiliza, solo, reactivos comunes y de muy bajo costo, como NaCl y ácido sulfúrico diluido. La ventaja de este procedimiento consiste en recuperar, a muy bajo coste, la totalidad del cobre soluble y entre 10 y 15% del cobre de sulfuros. El residuo final podría pasar a la pirometalurgia convencional
Modelación física del flujo de acero en un distribuidor de colada continua equipado con un inhibidor de turbulencia y una cortina de gas
Authors: Pérez-Labra M. , Díaz-Cruz M. , Palafox-Ramos J. , Ávila-Dávila E. O. , Patiño-Cardona F.
Published: February 2010

Usando el número de Froude como criterio de diseño se construyó un modelo de distribuidor, en acrílico, a 2/5 de la escala real, en el cual, ocho casos propuestos se estudiaron mediante la técnica PIV, manteniendo un flujo de gas constante de 596 ml/min y variando, solamente, la posición de la cortina de gas. Los resultados permitieron obtener curvas de distribución de tiempos de residencia (RTD) y, del procesamiento de los datos, se halló que la combinación del inhibidor de turbulencia (IT) con la adecuada posición de la cortina de gas presentó el mas alto volumen pistón. El caso VII presentó los mejores resultados, incrementando el volumen pistón en 131,85 % en comparación con el caso IV, que fue tomado como referencia.
Estudio de incertidumbre en la velocidad de corrosión atmosférica en acero de bajo carbono
Authors: Díaz V. , López C.
Published: February 2010

Rara vez, en la literatura de corrosión atmosférica se documenta el intervalo de confianza de las medidas de velocidad de corrosión, que depende del número de probetas y de la distribución de los datos. En este trabajo se realizaron experimentos específicos con muchas más probetas de las recomendadas, y se evaluó, para tiempos de exposición de 1, 2, 3 y 7 meses, el efecto de utilizar un mínimo de tres (como la norma sugiere para exposiciones de un año) y un máximo de once. Se ha podido confirmar así, la normativa vigente en relación a que estos valores se ajustan a una distribución normal. Se sugiere la determinación del número de probetas mínimo, en función de la atmósfera de estudio y del tiempo de exposición, dado que el número de réplicas actualmente empleado (para estudios con tiempos de exposición iguales o mayores a un año), puede resultar insuficiente para estudios de cinéticas asociadas a tiempos de exposición menores a un año.
Splicing of Distant Peptide Fragments Occurs in the Proteasome by Transpeptidation and Produces the Spliced Antigenic Peptide Derived from Fibroblast Growth Factor-5
Authors: Dalet Alexandre , Vigneron Nathalie , Stroobant Vincent , Hanada Ken-ichi , Van den Eynde Benoît J.
Published: February 2010

Peptide splicing is a newly described mode of production of antigenic peptides presented by MHC class I molecules, whereby two noncontiguous fragments of the parental protein are joined together after excision of the intervening segment. Three spliced peptides have been described. In two cases, splicing involved the excision of a short intervening segment of 4 or 6 aa and was shown to occur in the proteasome by transpeptidation resulting from the nucleophilic attack of an acyl-enzyme intermediate by the N terminus of the other peptide fragment. For the third peptide, which is derived from fibroblast growth factor-5 (FGF-5), the splicing mechanism remains unknown. In this case, the intervening segment is 40 aa long. This much greater length made the transpeptidation model more difficult to envision. Therefore, we evaluated the role of the proteasome in the splicing of this peptide. We observed that the spliced FGF-5 peptide was produced in vitro after incubation of proteasomes with a 49-aa-long precursor peptide. We evaluated the catalytic mechanism by incubating proteasomes with various precursor peptides. The results confirmed the transpeptidation model of splicing. By transfecting a series of mutant FGF-5 constructs, we observed that reducing the length of the intervening segment increased the production of the spliced peptide, as predicted by the transpeptidation model. Finally, we observed that trans-splicing (i.e., splicing of fragments from two distinct proteins) can occur in the cell, but with a much lower efficacy than splicing of fragments from the same protein.
SHIP Is Required for Dendritic Cell Maturation
Authors: Antignano Frann , Ibaraki Mariko , Kim Connie , Ruschmann Jens , Zhang Angela , Helgason Cheryl D. , Krystal Gerald
Published: February 2010

Although several groups have investigated the role of SHIP in macrophage (Mϕ) development and function, SHIP’s contribution to the generation, maturation, and innate immune activation of dendritic cells (DCs) is poorly understood. We show herein that SHIP negatively regulates the generation of DCs from bone marrow precursors in vitro and in vivo, as illustrated by the enhanced expansion of DCs from SHIP−/− GM-CSF cultures, as well as increased numbers of DCs in the spleens of SHIP-deficient mice. Interestingly, however, these SHIP−/− DCs display a relatively immature phenotype and secrete substantially lower levels of IL-12 after TLR ligand stimulation than wild type DCs. This, in turn, leads to a dramatically reduced stimulation of Ag-specific T cell proliferation and Th1 cell responses in vitro and in vivo. This immature phenotype of SHIP−/− DCs could be reversed with the PI3K inhibitors LY294002 and wortmannin, suggesting that SHIP promotes DC maturation by reducing the levels of the PI3K second messenger phosphatidylinositol-3,4,5-trisphosphate. These results are consistent with SHIP being a negative regulator of GM-CSF–derived DC generation but a positive regulator of GM-CSF–derived DC maturation and function.
Vγ9Vδ2 T Lymphocytes Efficiently Recognize and Kill Zoledronate-Sensitized, Imatinib-Sensitive, and Imatinib-Resistant Chronic Myelogenous Leukemia Cells
Authors: D’Asaro Matilde , La Mendola Carmela , Di Liberto Diana , Orlando Valentina , Todaro Matilde , Spina Marisa , Guggino Giuliana , Meraviglia Serena , Caccamo Nadia , Messina Angelo , Salerno Alfredo , Di Raimondo Francesco , Vigneri Paolo , Stassi Giorgio , Fourniè Jean Jacques , Dieli Francesco
Published: February 2010

Imatinib mesylate (imatinib), a competitive inhibitor of the BCR-ABL tyrosine kinase, is highly effective against chronic myelogenous leukemia (CML) cells. However, because 20–30% of patients affected by CML display either primary or secondary resistance to imatinib, intentional activation of Vγ9Vδ2 T cells by phosphoantigens or by agents that cause their accumulation within cells, such as zoledronate, may represent a promising strategy for the design of a novel and highly innovative immunotherapy capable to overcome imatinib resistance. In this study, we show that Vγ9Vδ2 T lymphocytes recognize, trogocytose, and efficiently kill imatinib-sensitive and -resistant CML cell lines pretreated with zoledronate. Vγ9Vδ2 T cell cytotoxicity was largely dependent on the granule exocytosis- and partly on TRAIL-mediated pathways, was TCR-mediated, and required isoprenoid biosynthesis by zoledronate-treated CML cells. Importantly, Vγ9Vδ2 T cells from patients with CML can be induced by zoledronate to develop antitumor activity against autologous and allogeneic zoledronate-treated leukemia cells, both in vitro and when transferred into immunodeficient mice in vivo. We conclude that intentional activation of Vγ9Vδ2 T cells by zoledronate may substantially increase their antileukemia activities and represent a novel strategy for CML immunotherapy.
Synthesis and characterization of heptacyclic laddersiloxanes and ladder polysilsesquioxane
Authors: Chang Shengho , Matsumoto Tomoe , Matsumoto Hideyuki , Unno Masafumi
Published: February 2010

As a continuation of our previous studies on thermostable materials, heptacyclic laddersiloxanes and ladder polysilsesquioxane were synthesized. The first heptacyclic laddersiloxanes were obtained by chlorination of pentacyclic laddersiloxanes prepared using our stereocontrolled synthesis procedure; thereafter, the heptacyclic laddersiloxanes were made to react with disiloxanediol. Ladder polysilsesquioxane was obtained from cis–trans–cis‐tetrabromotetramethylcyclotetrasiloxane by spontaneous hydrolysis and dehydration. The spectral and thermal properties of these new compounds were investigated. It was observed that the thermal stability of these compounds increases with the ring number. Copyright © 2010 John Wiley & Sons, Ltd.
On multidimensional convolutional codes and controllability properties of multidimensional systems over finite rings
Authors: Zerz Eva
Published: February 2010

Using the behavior‐code duality pointed out by Rosenthal et al., we study the relations between certain desirable features of a code and the corresponding controllability properties of its behavior. Module‐theoretic characterizations are provided as well. The coefficients of the codes and behaviors are taken to be integers modulo m, where m is not necessarily prime. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Animal models of early life stress: Implications for understanding resilience
Authors: Lyons David M. , Parker Karen J. , Schatzberg Alan F.
Published: February 2010

In the mid‐1950s, Levine and his colleagues reported that brief intermittent exposure to early life stress diminished indications of subsequent emotionality in rats. Here we review ongoing studies of a similar process in squirrel monkeys. Results from these animal models suggest that brief intermittent exposure to stress promotes the development of arousal regulation and resilience. Implications for programs designed to enhance resilience in human development are discussed. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 402–410, 2010.
Effects of postweaning social and physical deprivation on locomotor activity patterns and explorative behavior in female CD‐1 mice
Authors: Haupt Moritz , Schaefers Andrea T.U.
Published: February 2010

Social and physical deprivation during adolescence has detrimental consequences for brain maturation and cognitive functions. To test the hypothesis that social and physical deprivation during mouse adolescence would disrupt activity and exploration behavior, we exposed mice either to deprived or enriched rearing (postnatal days 21–60) and assessed activity and exploration of adult mice individually or in mixed treatment groups. In automated group compartments, deprived‐reared mice displayed higher locomotor activity, reduced explorative behavior and shifted activity timing compared to enriched‐reared mice. Contrastingly, distance and timing of wheel running were largely unaffected by deprived rearing. Our results demonstrate that postweaning social and physical deprivation has measurable effects on mouse locomotor and exploratory behavior, and that such effects may be discernable depending on the activity type studied. Our results further emphasize the importance of the sensitive postweaning period for shaping adult behavioral profiles. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 383–393, 2010.
Translating models of antisocial behavioral development into efficacious intervention policy to prevent adolescent violence
Authors: Dodge Kenneth A. , McCourt Sandra N.
Published: February 2010

Adolescent chronic antisocial behavior is costly but concentrated in a relatively small number of individuals. The search for effective preventive interventions draws from empirical findings of three kinds of gene‐by‐environment interactions: (1) parenting behaviors mute the impact of genes; (2) genes alter the impact of traumatic environmental experiences such as physical abuse and peer social rejection; and (3) individuals and environments influence each other in a dynamic developmental cascade. Thus, environmental interventions that focus on high‐risk youth may prove effective. The Fast Track intervention and randomized controlled trial are described. The intervention is a 10‐year series of efforts to produce proximal change in parenting, peer relations, social cognition, and academic performance in order to lead to distal prevention of adolescent conduct disorder. Findings indicate that conduct disorder cases can be prevented, but only in the highest risk group of children. Implications for policy are discussed. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 277–285, 2010
Mitochondria as a target in treatment
Authors: Frantz Marie‐Céline , Wipf Peter
Published: February 2010

Mitochondria are key organelles that perform essential cellular functions and play pivotal roles in cell death and survival signaling. Hence, they represent an attractive target for drugs to treat metabolic, degenerative, and hyperproliferative diseases. Targeting mitochondria with organelle‐specific agents or prodrugs has proven to be an effective therapeutic strategy. More specifically, controlling the cellular ROS balance via selective delivery of an antioxidant “payload” into mitochondria is an elegant emerging therapeutic concept. Herein, we review the recent medicinal chemistry and clinical data of these exploratory strategies, which should point the way for future generations of therapeutics. Environ. Mol. Mutagen. 2010. © 2010 Wiley‐Liss, Inc.
Prognostic importance of “clear versus revised margins” in oral and pharyngeal cancer
Authors: Kwok Pingling , Gleich Otto , Hübner Gerhard , Strutz Jürgen
Published: February 2010

Background.

Opinions differ regarding the usefulness of accurate, but costly, frozen sections. Most physicians believe that negative margins are essential for the prognosis of patients with oral and pharyngeal cancer. We examined whether immediate repeated resections in patients with positive margins, based on findings from frozen sections, resulted in improved patient survival.

Methods.

Data from 417 patients identified with cancer of the pharynx and floor of the mouth were analyzed retrospectively.

Results.

The 5‐year survival rate for R0 and R1–R0 groups was 72% to 76% and was significantly better (p ≤ .034) than that for R1 and R2 groups (58%, 40%). Despite clear margins, large tumors had a poorer prognosis than that of small tumors.

Conclusions.

Patients receiving repeated resection had the same survival rate as patients who had the tumor resected immediately with negative margins. The use of frozen sections yields a benefit for 15.6% of the operated patients and increases the overall 5‐year survival rate by 2% to 3%. © 2010 Wiley Periodicals, Inc. Head Neck, 2010
Roles of Hypoxia-Inducible Factor-1α (Hif-1α) Versus Hif-2α in the Survival of Hepatocellular Tumor Spheroids
Authors: Menrad Heidi , Werno Christian , Schmid Tobias , Copanaki Ekaterini , Deller Thomas , Dehne Nathalie , Brüne Bernhard
Published: February 2010

Hypoxia-inducible factors (HIFs) provoke adaptation to hypoxic stress occurring in rapidly growing tumor tissues. Therefore, overexpression of HIF-1 or HIF-2 is a common feature in hepatocellular carcinoma but their specific function is still controversially discussed. To analyze HIF function in hypoxia-induced cell death we created a stable knockdown of HIF-1α and HIF-2α in HepG2 cells and generated tumor spheroids as an

in vitro

hepatocellular carcinoma model. Knockdown of HIF-1α enhanced expression of HIF-2α and vice versa. Unexpectedly, knockdown of HIF-1α or HIF-2α increased cell viability as well as spheroid size and decreased caspase-3 activity. Antiapoptotic Bcl-XL expression increased in both knockdown spheroids, whereas proapoptotic Bax was only reduced in HIF-1α-knockdown cells. Furthermore, an HIF-2α-knockdown significantly increased Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 (BNIP3) expression in an HIF-1α-dependent manner. Concomitantly, electron microscopy revealed a substantial increase in autophagosomal structures in HIF-2α-knockdown spheroids and mito-/lysotracker costaining confirmed lysosomal activity of these autophagosomes. Blocking autophagosome maturation using 3-methyladenine restored cell death in HIF-2α-knockdown clones comparable to wildtype cells.

Conclusion

: An HIF-1α-knockdown increases HIF-2α expression and shifts the balance of Bcl-2 family members toward survival. The knockdown of HIF-2α raises autophagic activity and attenuates apoptosis by enhancing HIF-1α expression. Our data indicate that enhanced expression of one HIF-isoform causes a survival advantage in hepatocellular carcinoma development. Hepatology 2010
Preapoptotic Cell Stress Response of Primary Hepatocytes
Authors: Nipič Damijan , Pirc Aleš , Banič Blaž , Šuput Dušan , Milisav Irina
Published: February 2010

Primary hepatocytes are an important

in vitro

model for studying metabolism in man. Caspase-9 and Bcl-2-associated X protein (Bax) are regulators of the apoptotic pathway. Here we report on the translocation of procaspase-9 and Bax from cytoplasm to nuclei as well as on dispersion of mitochondria; these processes occur after isolation of primary hepatocytes. The observed changes appear similar to those at the beginning of apoptosis; however, the isolated hepatocytes are not apoptotic for the following reasons: (1) cells have a normal morphology and function; (2) the mitochondria are energized; (3) there is no apoptosis unless it is induced by, e.g., staurosporine or nodularin. Staurosporine does not trigger apoptosis through activation of caspase-9, as its activity is detected later than that of caspase-3. We propose that the translocation of procaspase-9 and Bax into the nuclei reduces the ability to trigger apoptosis through the intrinsic apoptotic pathway. The shifts of procaspase-9 and Bax are reversible in the absence of the apoptotic trigger; the spontaneous reversion was confirmed experimentally for procaspase-9, whereas Bax shifted from the nuclei to the cytosol and mitochondria after the initiation of apoptosis. To distinguish this process from apoptosis, we call it preapoptotic cell stress response. It shares some features with apoptosis; however, it is reversible and apoptosis has to be induced in addition to this process.

Conclusion

: Knowledge on preapoptotic cell stress response is important for assessing the quality of the cells used in cell therapies, in regenerative medicine, and of those used for modeling metabolic processes. Hepatology 2010;51:2140–2151
Toxic effects of ethanol on bovine serum albumin
Authors: Liu Rutao , Qin Pengfei , Wang Li , Zhao Xingchen , Liu Yihong , Hao Xiaopeng
Published: February 2010

The toxic effects of ethanol on bovine serum albumin (BSA) were measured by resonance light scattering (RLS), fluorescence spectroscopy, ultraviolet spectrophotometry (UV), circular dichroism (CD), and transmission electron microscopy (TEM). The results indicated that ethanol had toxic effects on BSA, which led to protein denaturation and the effects increased with the ethanol dose. By means of RLS, BSA was found to aggregate in the presence of ethanol and particles smaller than 100 nm were observed from TEM. The fluorescence spectra showed that the intensity of the characteristic peak of BSA decreased and blue shifted, because of changes in the BSA skeleton structure, as well as alteration of the microenvironment of tryptophan (Trp) residues. The conformation changes of BSA were also shown by UV and CD spectrometry. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:66–71, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20314
Grape seed proanthocyanidins attenuate vascular smooth muscle cell proliferation via blocking phosphatidylinositol 3‐kinase‐dependent signaling pathways
Authors: Wang Lang , Zhu Li‐Hua , Jiang Hong , Tang Qi‐Zhu , Yan Ling , Wang Dong , Liu Chen , Bian Zhou‐Yan , Li Hongliang
Published: February 2010

The excess generation of reactive oxygen species (ROS) play important role in the development and progression of diabetes and related vascular complications. Therefore, blocking the production of ROS will be able to improve hyperglycemia‐induced vascular dysfunction. The objective of this study was to determine whether a novel IH636 grape seed proanthocyanidins (GSPs) could protect against hyperproliferation of cultured rat vascular smooth muscle cells (VSMCs) induced by high glucose (HG) and determine the related molecular mechanisms. Our data demonstrated that GSPs markedly inhibited rat VSMCs proliferation as well as ROS generation and NAPDH oxidase activity induced by HG treatment. Further studies revealed that HG treatment resulted in phosphorylation and membrane translocation of Rac1, p47phox, and p67phox subunits leading to NADPH oxidase activation. GSPs treatment remarkably disrupted the phosphorylation and membrane translocation of Rac1, p47phox, and p67phox subunits. More importantly, our data further revealed that GSPs significantly disrupted HG‐induced activation of ERK1/2, JNK1/2, and PI3K/AKT/GSK3β as well as NF‐κB signalings, which were dependent on reactive oxygen species (ROS) generation and Rac1 activation. In addition, our results also demonstrated that HG‐induced cell proliferation and excess ROS production was dependent on the activation of PI3 kinase subunit p110α. Collectively, these results suggest that HG‐induced VSMC growth was attenuated by grape seed proanthocyanidin (GSPs) treatment through blocking PI3 kinase‐dependent signaling pathway, indicating that GSPs may be useful in retarding intimal hyperplasia and restenosis in diabetic vessels. J. Cell. Physiol. 223:713–726, 2010. © 2010 Wiley‐Liss, Inc.
Nonprofit mergers: Assessing the motivations and means
Authors: Pietroburgo Julie , Wernet Stephen P.
Published: February 2010

As nonprofit organizations seek to remain viable in an increasingly competitive environment, merger is an attractive (albeit complicated) option. This case study of the largest nonprofit association merger in U.S. history, involving three bowling associations, demonstrates the critical role of leadership in consummating a merger. The case illustrates a number of factors necessary to merger success: existence of a catalyst leader and a nucleus of like‐minded individuals who can serve as the impetus for change, sufficient time to accommodate the psychological and practical aspects of merging, opportunities for building social capital among the people involved in the merger, and preservation of cultural remnants that are carried over from the predecessor organizations to the newly merged entity.
Raman study of Fano interference in p‐type doped silicon
Authors: Burke Brian G. , Chan Jack , Williams Keith A. , Wu Zili , Puretzky Alexander A. , Geohegan David B.
Published: February 2010

As the silicon industry continues to push the limits of device dimensions, tools such as Raman spectroscopy are ideal to analyze and characterize the doped silicon channels. The effect of inter‐valence band transitions on the zone center optical phonon in heavily p‐type doped silicon is studied by Raman spectroscopy for a wide range of excitation wavelengths extending from the red (632.8 nm) into the ultra‐violet (325 nm). The asymmetry in the one‐phonon Raman lineshape is attributed to a Fano interference involving the overlap of a continuum of electronic excitations with a discrete phonon state. We identify a transition above and below the one‐dimensional critical point (E = 3.4 eV) in the electronic excitation spectrum of silicon. The relationship between the anisotropic silicon band structure and the penetration depth is discussed in the context of possible device applications. Copyright © 2010 John Wiley & Sons, Ltd.
Raman study of pressure‐induced phase transitions in crystals of orthorhombic and monoclinic polymorphs of L‐cysteine: dynamics of the side chain
Authors: Minkov Vasily S. , Goryainov Sergei V. , Boldyreva Elena V. , Görbitz Carl Henrik
Published: February 2010

The series of phase transitions on increasing pressure and on reverse decompression was followed in crystals of monoclinic and orthorhombic polymorphs of L‐cysteine by using Raman spectroscopy, with the samples placed in a diamond anvil cell together to ensure identical pressures on the two samples. The effects of hydrostatic pressure on the two polymorphs are shown to be radically different. Depending on the starting polymorph, different phases are formed under identical compression/decompression conditions. The effect of pressure on the monoclinic polymorph was studied for the first time. Phase transitions in monoclinic L‐cysteine (at ∼2.9 and ∼3.9 GPa) are completely reversible without a noticeable hysteresis. The changes in the spectra suggest that the H‐bond network is distorted and SH···O bonding dominates over SH···S bonding at high pressures, but the molecular conformations change continuously during these transitions. The data on the orthorhombic polymorph of L‐cysteine show that not only the H‐bond network is distorted, but also the conformation of the L‐cysteine zwitterion changes very substantially. The previously observed discrepancy in the results related to the occurrence of a phase existing between 2.1 and 2.3 GPa reported by Minkov et al. (J. Phys. Chem. B. 2008; 112, 8851) but not observed by Moggach et al. (Acta Crystallogr. B. 2006; 62, 296) could be interpreted; different phases can be formed at the same pressure, depending on how this pressure was reached: on direct compression, or in the compression–decompression–compression cycle. Copyright © 2010 John Wiley & Sons, Ltd.
A potential microRNA signature for tumorigenic conazoles in mouse liver
Authors: Ross Jeffrey A. , Blackman Carl F. , Thai Sheau‐Fung , Li Zhiguang , Kohan Michael , Jones Carlton P. , Chen Tao
Published: February 2010

Triadimefon, propiconazole, and myclobutanil are conazoles, an important class of agricultural fungicides. Triadimefon and propiconazole are mouse liver tumorigens, while myclobutanil is not. As part of a coordinated study to understand the molecular determinants of conazole tumorigenicity, we analyzed the microRNA expression levels in control and conazole‐treated mice after 90 d of administration in feed. MicroRNAs (miRNAs) are small noncoding RNAs composed of approximately 19–24 nucleotides in length, and have been shown to interact with mRNA (usually 3′ UTR) to suppress its expression. MicroRNAs play a key role in diverse biological processes, including development, cell proliferation, differentiation, and apoptosis. Groups of mice were fed either control diet or diet containing 1800 ppm triadimefon, 2500 ppm propiconazole, or 2000 ppm myclobutanil. MicroRNA was isolated from livers and analyzed using Superarray whole mouse genome miRNA PCR arrays from SABioscience. Data were analyzed using the significance analysis of microarrays (SAM) procedure. We identified those miRNAs whose expression was either increased or decreased relative to untreated controls with q ≤ 0.01. The tumorigenic conazoles induced many more changes in miRNA expression than the nontumorigenic conazole. A group of 19 miRNAs was identified whose expression was significantly altered in both triadimefon‐ and propiconazole‐treated animals but not in myclobutanil‐treated animals. All but one of the altered miRNAs were downregulated compared to controls. This pattern of altered miRNA expression may represent a signature for tumorigenic conazole exposure in mouse liver after 90 d of treatment. Published 2010 Wiley‐Liss, Inc.
Ferritin as a reporter gene for MRI: chronic liver over expression of h‐ferritin during dietary iron supplementation and aging
Authors: Ziv Keren , Meir Gila , Harmelin Alon , Shimoni Eyal , Klein Eugenia , Neeman Michal
Published: February 2010

The iron storage protein, ferritin, provides an important endogenous MRI contrast that can be used to determine the level of tissue iron. In recent years the impact of modulating ferritin expression on MRI contrast and relaxation rates was evaluated by several groups, using genetically modified cells, viral gene transfer and transgenic animals. This paper reports the follow‐up of transgenic mice that chronically over‐expressed the heavy chain of ferritin (h‐ferritin) in liver hepatocytes (liver‐hfer mice) over a period of 2 years, with the aim of investigating the long‐term effects of elevated level of h‐ferritin on MR signal and on the well‐being of the mice. Analysis revealed that aging liver‐hfer mice, exposed to chronic elevated expression of h‐ferritin, have increased R2 values compared to WT. As expected for ferritin, R2 difference was strongly enhanced at high magnetic field. Histological analysis of these mice did not reveal liver changes with prolonged over expression of ferritin, and no differences could be detected in other organs. Furthermore, dietary iron supplementation significantly affected MRI contrast, without affecting animal wellbeing, for both wildtype and ferritin over expressing transgenic mice. These results suggest the safety of ferritin over‐expression, and support the use of h‐ferritin as a reporter gene for MRI. Copyright © 2010 John Wiley & Sons, Ltd.
Study of the interfacial properties of amorphous silicon/n‐type crystalline silicon heterojunction through static planar conductance measurements
Authors: Favre W. , Labrune M. , Dadouche F. , Gudovskikh A. S. , Cabarrocas P. Roca i , Kleider J. P.
Published: February 2010

We have previously shown from static planar conductance measurements that a strong inversion layer does exist in c‐Si at the (n) a‐Si:H/ (p) c‐Si interface. This allowed us to determine the conduction band offset with a good precision (ΔEC = 0.15 +/– 0.04 eV). The same technique is now applied to study (p) a‐Si:H/ (n) c‐Si interfaces. We demonstrate that a strong inversion layer (of holes) also exists at the c‐Si surface of this hetero‐interface. Analysis of our planar conductance data with the help of numerical simulations allows us to set a lower limit to the valence band offset, ΔEV = EV,a‐Si:H − EV, c‐Si: ΔEV > 0.28 eV. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High density lipoprotein inhibits the activation of sterol regulatory element‐binding protein‐1 in cultured cells
Authors: Yoshida Masaki , Harada Nagakatsu , Yoshida Keiko , Nakagawa Tadahiko , Shimohata Takaaki , Mawatari Kazuaki , Takahashi Akira , Sakaue Hiroshi , Nakaya Yutaka
Published: February 2010

A link between cellular uptake of high density lipoprotein (HDL) and regulation of sterol regulatory element‐binding protein‐1 (SREBP‐1) was investigated in vitro. HDL decreased nuclear SREBP‐1 levels as well as SREBP‐1 target gene expression in HepG2 and HEK293 cells. However, HDL did not repress an exogenously expressed, constitutively active form of SREBP‐1. HDL increased cellular cholesterol levels, and cellular cholesterol depletion by methyl‐β‐cyclodextrin abolished the effects of HDL. These results suggest that HDL inhibits the activation of SREBP‐1 through a cholesterol‐dependent mechanism, which may play an important role in regulating lipid synthetic pathways mediated by SREBP‐1.
N‐terminal PH domain and C‐terminal auto‐inhibitory region of CKIP‐1 coordinate to determine its nucleus‐plasma membrane shuttling
Authors: Xi Shenli , Tie Yi , Lu Kefeng , Zhang Minghua , Yin Xiushan , Chen Jie , Xing Guichun , Tian Chunyan , Zheng Xiaofei , He Fuchu , Zhang Lingqiang
Published: February 2010

The pleckstrin homology (PH) domain‐containing protein casein kinase 2 interacting protein‐1 (CKIP‐1) plays an important role in regulation of bone formation and muscle differentiation. How CKIP‐1 localization is determined remains largely unclear. We observed that isolated CKIP‐1‐PH domain was predominantly localized in the nucleus and the C‐terminus of CKIP‐1 counteracted its nuclear localization. The net charge of basic residues and a serine‐rich motif within the PH domain plays a pivotal role in the localization switch of both full‐length CKIP‐1 and the isolated PH domain. We propose that the N‐terminal PH domain and C‐terminal auto‐inhibitory region of CKIP‐1 coordinate to determine its subcellular localization and the nucleus–plasma membrane shuttling.