bluuebunny/crossref_metadata_2025 huggingface dataset:
Multimodal Approach to Low-Cost Improvements Addressing Freight Mobility Constraints
Authors: Fekpe Edward
Published: October 2010

Freight mobility is constrained not only by physical infrastructure inadequacies but also by operational, regulatory, policy, technological, and financial limitations. The capacity of the existing freight transportation system can be increased through innovative operational strategies, performance-improving regulatory and policy changes, and low-cost capital improvements. This paper defines freight mobility constraints in a multimodal context, identifies the primary causes of the constraints, develops criteria for low-cost improvements that can be quickly implemented, and presents examples of practical, low-cost improvements to address mobility constraints encountered in moving freight by highway, by rail, and through deepwater ports and inland waterways. The paper also presents the framework for a methodology that can be used by public-sector agencies to evaluate mobility constraints and select low-cost improvements derived from implemented projects.
Modeling and Performance Assessment of Intermodal Transfers at Cargo Terminals
Authors: Chen Cheng-Chieh (Frank) , Schonfeld Paul
Published: October 2010

This study develops an analytical model for coordinating vehicle schedules and cargo transfers at cargo terminals to improve system operational efficiency and minimize total system costs. The studied problem is formulated as a multihub, multimode, and multicommodities network problem with nonlinear time value functions for shipped cargo. This is done primarily by optimizing service frequencies and slack times for system coordination while also considering loading and unloading, storage, and cargo processing operations at the transfer terminals. In a series of case studies, the model has shown its ability to determine optimal service frequencies (or headways) and slack times based on given inputs. Numerical results are solved using sequential quadratic programming and a genetic algorithm.
Truck Productivity, Efficiency, Energy Use, and Carbon Dioxide Output
Authors: Woodrooffe John , Glaeser Klaus-Peter , Nordengen Paul
Published: October 2010

The Joint Transport Research Centre of the Organisation for Economic Co-operation and Development and the International Transport Forum recently conducted a benchmarking study of the safety and productivity of typical highway transport trucks from various countries. This paper focuses on vehicle productivity and efficiency in regard to the movement of freight. Forty vehicles from 10 countries were examined. The vehicles were designed for longer-haul applications and were classified in three separate categories: workhorse vehicles, which are the most common and can travel on most roads; high-capacity vehicles, which may be restricted to a certain class of road; and very high-capacity vehicles, which may be restricted to specific highways or routes. The metrics used in the analysis include maximum cargo mass and volume capacity, optimum cargo density, fuel consumption, and carbon dioxide output as a function of the freight task. The study found that size and weight regulations have a significant effect on the productivity and efficiency of heavy vehicles, including fuel consumption and vehicle emissions per unit of cargo transported. Significant variations were found among the vehicles from participating countries as well as within vehicle classes. It was also apparent that, in general, higher-productivity vehicles are correlated more strongly with increased cargo volume than with increased cargo mass and that larger trucks are better suited to lower-density freight than are workhorse vehicles. The study also found that it is important to consider the freight task when evaluating vehicle fuel consumption and emissions.
Intra-Industry Trade Analysis of U.S. State–Canadian Province Pairs
Authors: Kristjánsson Kristján Árni , Bomba Michael , Goodchild Anne V.
Published: October 2010

Intra-industry trade (IIT) occurs when trading partners import and export similar products. A high volume of IIT of horizontally differentiated goods implies a deep level of regional integration, stable regional trading patterns, and potentially significant consequences from border delay. In this paper, trade between Washington State and British Columbia, Canada (the Cascade gateway), is compared with trade between Michigan State and Ontario, Canada (the Great Lakes gateway). The Grubel–Lloyd index, which measures IIT, is used to analyze trade in these two corridors. Higher levels of IIT and regional integration within the Great Lakes gateway are shown. The paper argues that cross-border supply chains most exposed to higher cost from increasing border delays are composed of horizontally differentiated manufactured goods having high levels of IIT and relying heavily on truck transportation. These types of goods are more common in the Great Lakes gateway, and this region may therefore experience greater economic impacts from long and unpredictable delays than the Cascade gateway.
Documenting Truck Activity Times at International Border Crossings Using Redesigned Geofences and Existing Onboard Systems
Authors: McCord Mark R. , Goel Prem K. , Brooks Colin , Kapat Prasenjit , Wallace Richard , Dong Hao , Keefauver D. Eric
Published: October 2010

When crossing international gateways, commercial vehicles engage in multiple activities—such as approaching on congested roadways, paying tolls, undergoing customs inspections, and waiting in queues—that increase trip times and trip-time variability. Documenting the times incurred in these multiple activities is difficult because the activities are spatially dispersed, temporally variant, and affected by institutional and operational complexities resulting from the multiple organizations operating infrastructure in two countries. An approach is presented to capture the times required to complete various activities at international border crossings, using trucks from a large fleet that regularly crosses international gateways. This approach takes advantage of the telematics systems already in use by the truck fleet and is not dependent on installation of roadside equipment. Geofences are specified at strategic locations that delineate the beginnings and ends of activities of interest and send information electronically to the vehicles' onboard data units. The activity times for an individual truck crossing can be determined from data automatically recorded when trucks enter and exit the specified geofences. The trucks serve as activity time probes, and the activity times of multiple trucks can be aggregated to form activity time distributions. To demonstrate the capabilities and potential of the approach, empirical data from a large fleet of trucks traversing two of the busiest U.S. border crossings are used to produce results on median crossing times, variability in trip times, time-of-day patterns, and excess times (i.e., delays) generated from customs inspections and the queuing that results from the inspections.
Macroeconomic Effects of Road Corridor Investment in Kazakhstan
Authors: Norojono Olly , Roland-Holst David , Sugiyarto Guntur
Published: October 2010

Infrastructure development across Central Asia facilitates connectivity, competitiveness, productivity, and ultimately economic growth and regional integration. A sample development project is a large road corridor in Kazakhstan. This report shows the economic impact of such a project. The quantitative work follows a dynamic general equilibrium model covering both direct and indirect effects, including trade facilitation, transport cost reduction, and increased productivity. The cumulative indirect impacts benefit Kazakhstan and the many economies linked to it.
Risk Assessment for Transportation of Hazardous Materials through Tunnels
Authors: Nathanail E. G. , Zaharis S. , Vagiokas N. , Prevedouros P. D.
Published: October 2010

Two vehicle collisions involving hazardous materials (HM) occurred in 1999 in the tunnels of Mont Blanc between Italy and France and in Tauern, Austria. These collisions showed that the consequences of such crashes are catastrophic for both the motorists in the tunnel and the tunnel itself. This paper presents a methodology to help decision makers estimate the risk associated with the transportation of HM through tunnels and identify remedial measures to minimize unacceptable risk levels. A risk assessment procedure is used to identify the societal risk of the tunnel. If the risk is above an acceptable level, alternative routes are considered, and the overall risk is estimated for both the route with the tunnel and the alternative routes. The route with the minimum risk is established. If the route of minimum risk is through the tunnel, then risk reduction measures are introduced and the risk assessment methodology is implemented to verify the result. The full implementation of the methodology is demonstrated in a case study. The characteristics of the tunnels, the type of HM, and the characteristics of the traffic and accident risk at each tunnel are accounted for. Given an estimate of risk for a tunnel produced by the analytical procedure used in this paper, the applicable regulatory criteria at a given location are found to substantially affect the required response. The response may vary from “no restriction to HM traffic,” to “remedies required,” to “total restriction of HM type X is advised” for the subject tunnel. The case study considers several remedial actions and assesses their impact on risk and subsequent recommended actions.
L'expérience britannique (1876-1912). Les années d'expectative
Authors: Perry Charles R. ,   MIT Press
Published: October 2010

The lack of littérature on the subject testifies to the fact that the British were far less interested in the telephone in its infancy than in the railroad. From its advent in 1876 until its naturalization in 1912, the novelty's handicap was twofold - a lack of available funds, and political hesitation regarding a public or private status. Scepticism shown by the press and relaying institutions as a whole contrasted with the dynamism manifested during the same period with regard to the rapid development of new technologies.
Microsatellite loci for Paspalum atratum (Poaceae) and cross‐amplification in other species
Authors: Cidade F. W. , de Souza‐Chies T. T. , Souza F. H. D. , Batista L. A. R. , Dall'Agnol M. , Valls J. F. M. , Zucchi M. I. , Souza A. P.
Published: October 2010

• Premise of the study: Paspalum atratum is a perennial, cespitose, tropical grass native to Central and South America. This species belongs to a polyploid complex (Plicatula group) little known at the genetic level. The characterized microsatellite markers provide new informative tools for further studies of the hybridization, mating systems, and structure of the population.

• Methods and Results: Using the microsatellite‐enriched library method, we isolated and characterized 19 microsatellite markers from P. atratum. Eleven of them were polymorphic, showing a variable degree of variation, while eight were monomorphic in the samples analyzed. Additionally, the transferability of these microsatellite markers was tested in other species.

• Conclusions: These results suggest that the characterized markers have enough discriminatory potential to be used in genetic characterizations of Paspalum taxa, which are based on an understanding of their mating systems and genetic structure, as well as in understanding the evolutionary processes involved in the evolution of groups of Paspalum.
Quantitative Power Doppler Ultrasonography Is a Sensitive Measure of Metacarpophalangeal Joint Synovial Vascularity in Rheumatoid Arthritis and Declines Significantly Following a 2-week Course of Oral Low-dose Corticosteroids
Authors: LARCHÉ MAGGIE J. , SEYMOUR MATTHEW , LIM ADRIAN , ECKERSLEY ROBERT J. , PÉTAVY FRANK , CHIESA FLAMINIA , RIOJA INMACULADA , LUKEY PAULINE T. , BINKS MICHAEL , McCLINTON CATHERINE , DOLAN KATHLEEN , TAYLOR PETER C.
Published: October 2010

Objective.

To investigate the stability over 2 weeks of ultrasonographic assessments of synovial thickness and vascularity in all 10 metacarpophalangeal joints of subjects with rheumatoid arthritis (RA) with a range of disease activities as measured by the validated Disease Activity Score-28 joint score (DAS28-ESR). And in subjects with severe disease activity, to compare the sensitivity of these measurements, acute-phase markers, and vascular endothelial growth factor to change in response to 2 weeks of oral prednisolone (7.5 mg daily).

Methods.

A group of 38 subjects with RA were enrolled, 13 (mean DAS28 2.1), 14 (mean DAS28 5.2), and 11 (mean DAS28 5.7) meriting oral corticosteroid treatment. Synovial thickness and vascularity were assessed by ultrasonography at 3 timepoints. Images were ranked by semiquantitative scale. Vascularity was also measured by quantitative determination of the power Doppler area (PDA).

Results.

In the whole RA cohort, baseline indices of synovial thickness and vascularity correlated with DAS28, as did PDA (r = 0.42, p < 0.05). In the RA groups on stable therapy, synovial thickness and vascularity showed little variation over 2 weeks. In the corticosteroid group, PDA had fold changes of −1.9-fold (p < 0.05) after 1 week and −2.2-fold (p < 0.05) after 2 weeks. These were the largest fold changes of all measured variables.

Conclusion.

Ultrasonographic measures can differentiate disease severity in RA correlating closely with DAS28. Quantitative power Doppler signal was significantly reduced within 1 week of oral prednisolone, a rapid kinetic suggesting that PDA may have value as a sensitive early marker of therapeutic response.
Systematic Review of MRI, Ultrasound, and Scintigraphy as Outcome Measures for Structural Pathology in Interventional Therapeutic Studies of Knee Arthritis: Focus on Responsiveness
Authors: KEEN HELEN I. , MEASE PHILIP J. , BINGHAM CLIFTON O. , GILES JON T. , KAELEY GURJIT , CONAGHAN PHILIP G.
Published: October 2010

Objective.

Validated imaging outcome tools to assess response to therapies in a single joint are required. Our aim was to review the published literature to ascertain the responsiveness of novel imaging techniques as outcome measures in interventional therapeutic studies of knee arthritis.

Methods.

An Ovid Medline search was performed for original articles in English that used imaging techniques to assess response at the knee joint to therapy in osteoarthritis, rheumatoid arthritis, and psoriatic arthritis. Changes in response to therapy were assessed with regard to both internal and external responsiveness.

Results.

In the studies that presented appropriate statistical data to allow responsiveness to be assessed, MRI was generally found to be internally responsive to pathologies imaged, and externally responsive, referenced against both other imaging modalities and biochemical biomarkers of arthritis. Ultrasonography was found to demonstrate internal responsiveness with regard to synovial thickness, effusion size, and popliteal cyst size. External responsiveness was demonstrated against several referenced health status measures. Scintigraphy was found to be externally responsive in the majority of studies, with internal responsiveness demonstrated in 1 study.

Conclusion.

While the imaging techniques appear to be responsive from the data we present, further inspection reveals that interpreting the responsiveness of imaging techniques was difficult, largely because of a lack of standardization of image acquisition, definitions of pathology, and scoring systems. Refined pathological definitions and scoring systems are required to enable the development of valid and responsive tools for interventional clinical trials.
Anticentromere-A and Anticentromere-B Antibodies Show High Concordance and Similar Clinical Associations in Patients with Systemic Sclerosis
Authors: HANKE KATHARINA , BECKER MIKE O. , BRUECKNER CLAUDIA S. , MEYER WOLFGANG , JANSSEN ANTHONINA , SCHLUMBERGER WOLFGANG , HIEPE FALK , BURMESTER GERD-R. , RIEMEKASTEN GABRIELA
Published: October 2010

Objective.

To determine the diagnostic sensitivity and specificity and the clinical usefulness of parallel anticentromere-A and anticentromere-B antibody (anti-CENP-A and anti-CENP-B) testing in patients with systemic sclerosis (SSc).

Methods.

Sera from 280 consecutive patients with SSc and 259 controls were tested for the presence of anti-CENP-A and anti-CENP-B antibodies by a monospecific line immunoblot assay (LIA) with recombinant human centromere proteins A and B as well as by indirect immunofluorescence (IIF). Crossreactivity and possible associations with clinical manifestations were studied.

Results.

Both antibodies revealed a diagnostic sensitivity of 36.8% and a specificity of > 97% for SSc, with a high concordance rate of 94.3% despite different amino acid sequences of the antigens and absence of crossreactivity. There was a significant correlation of the antibody levels measured by LIA. Both antibodies were associated with similar clinical manifestations and identified patients with limited disease and rather mild skin sclerosis.

Conclusion.

Detected by LIA, anti-CENP-A and anti-CENP-B antibodies show high concordance in patients with SSc and share significant associations to clinical manifestations, but are not completely identical. Detection of both antibodies in parallel may slightly increase the diagnostic sensitivity for SSc.
Influencia del nitruro de aluminio en el crecimiento anormal de grano de aceros microaleados
Authors: Cabrera J. M. , Al Omar A. , Prado J. M.
Published: October 2010

Tras una breve revisión de los conceptos y teorías involucradas en el control del crecimiento de grano por partículas de segunda fase, se efectúa un estudio del mismo en un acero microaleado con contenido medio de carbono con dos niveles de nitruro de aluminio. Se propone un sistema de estudio de las distribuciones de tamaño de grano tendente a poder detectar la presencia de crecimiento anormal de grano. De este modo, se construyen mapas de crecimiento anormal-tiempo-temperatura que, correlacionados con las teóricas fracciones de volumen de los precipitados presentes, permiten comprobar que la disolución del nitruro de aluminio es la responsable fundamental de la aparición del crecimiento anormal de grano. También se muestra el efecto e importancia de la velocidad de calentamiento, ya que altas velocidades pueden producir una sobresaturación transitoria de precipitados que, al disolverse, pueden dar lugar a crecimiento de grano anormal.
La etapa de contacto líquido-líquido operando en corriente cruzada
Authors: Otero de la Gándara J. L.
Published: October 2010

Se describe una nueva variante de etapa de contacto líquido-líquido. El flujo de fases se realiza fraccionando la fase orgánica en varias corrientes y la fase acuosa se desplaza a través de conductos ascendentes y descendentes dispuestos en zig-zag y conectados en serie. Cada fracción de flujo de fase orgánica se alimenta en la base de los conductos en los que la fase acuosa asciende. En estos conductos tiene lugar la transferencia de materia entre fases, que se facilita mediante la utilización de un relleno convencional. La coalescencia de la fase orgánica se produce en la zona superior de estos conductos. La etapa se comporta produciendo una variación de concentraciones superior a la correspondiente a una etapa teórica convencional. Se resalta la reducción importante del consumo de energía en el contacto de fases y el bajo retenido de fase orgánica, en relación con un mezclador-sedimentador convencional.
Eliminación de arsénico. Etapa indispensable en el reciclado de residuos
Authors: Gaballah I. , Menad N. , Garcí-Carcedo F. , Siguín D. , Ferreira S.
Published: October 2010

Se describen los efectos de los tratamientos térmicos a diferentes temperaturas y atmósferas sobre las transformaciones fisicoquímicas de residuos hidrometalúrgicos que contienen elementos tóxicos tales como arsénico, mercurio, cadmio, selenio, etc. Se estudian, además, los rendimientos de extracción de estos elementos tóxicos en función de los tratamientos, dedicando particular atención a la eliminación de arsénico de estos residuos. Si bien ciertos tratamientos permiten eliminar alrededor del 97 % de los elementos tóxicos y duplicar la concentración de los valores metálicos, parece que la descontaminación total de estas muestras, en atmósferas controladas, necesita sucesivos tratamientos térmicos.
Interacción térmica recubrimiento-sustrato en la proyección a alta velocidad (HVOF) de partículas (polvo) de WC-Co
Authors: Sobolev V. V. , Guilemany J. M. , Calero J. A.
Published: October 2010

Se utiliza la simulación matemática para establecer la interacción térmica entre un substrato y un recubrimiento obtenido mediante proyección térmica de alta velocidad, HVOF. El substrato es un acero 34CrMo4(UNS-G41350) y el recubrimiento está formado por la solidificación de gotas semifundidas de partículas de polvo de WC-12 % Co. El análisis del proceso de transferencia de calor permite la investigación de la evolución de la temperatura, la solidificación del recubrimiento, la fusión y posterior solidificación del substrato, las características peculiares de la interacción térmica entre el substrato y la primera capa de recubrimiento, así como con las diferentes capas sucesivas, y la estimación de las condiciones óptimas para la formación de la estructura del substrato y del recubrimiento. Los resultados obtenidos se han utilizado en posteriores artículos para predecir parámetros estructurales que están, por su parte, en concordancia con los datos experimentales.
El refino del oro
Authors: Alguacil F. J.
Published: October 2010

Hasta la introducción de los nuevos procesos para el refino del oro, basados en circuitos de lixiviación de lodos auríferos o en la extracción con disolventes, la recuperación de este metal precioso ha permanecido sin alterar desde hace un siglo. El presente trabajo evalúa los procesos clásicos utilizados, así como las modernas propuestas en las que como objetivo principal se pretende la obtención de disoluciones libres de oro que facilitan su posterior tratamiento.
El refino de los metales del grupo del platino
Authors: Alguacil F. J.
Published: October 2010

En un trabajo anterior se describieron los procesos que permiten obtener disoluciones libres de oro y abordar la recuperación de los metales del grupo del platino. En el presente trabajo se evalúan los procesos clásicos para el refino de estos metales. Asimismo, se discuten los nuevos procesos de refinación basados en la aplicación de la extracción con disolventes.
Extracción del cinc y otros metales minoritarios de soluciones concentradas de cloruro amónico con D2EHPA y Cyanex 272
Authors: Amer S. , Luis A.
Published: October 2010

Se realiza un estudio comparativo del comportamiento del D2EHPA y del Cyanex 272 durante la extracción del cinc y otros metales minoritarios de soluciones acuosas concentradas de cloruro amónico, como las de las soluciones de lixiviación del proceso CENIM-LNETI. Se presentan los datos de equilibrio de extracción del cinc en forma de isotermas de extracción a una temperatura de 50 °C y pH constante y se estudia la coextracción de los metales minoritarios Cu, Ca, Pb, Mg, Cd, Co, Ni y Hg. El mercurio no se extrae de las soluciones concentradas de cloruro amónico. La selectividad del Cyanex 272 para el cinc respecto de esos metales minoritarios es mejor que la del D2EHPA, siendo verdaderamente notable para el calcio, que es la impureza que más se coextrae con el D2EHPA. La coextracción de níquel y de cadmio es muy pequeña para ambos extractantes. Se considera la posibilidad del uso alternativo del Cyanex 272 en lugar del D2EHPA.
Recursos y alternativas de tratamiento para los minerales de teluro de Sonora (México)
Authors: Aguayo S. , Pérez E. , Encinas M. A.
Published: October 2010

El teluro es un elemento escaso, pero con un espectro amplio de aplicaciones. Su producción está limitada a la obtenida por el tratamiento de los lodos electrolíticos de las refinerías de cobre. De las fuentes alternativas de teluro, los telururos de metales preciosos son atractivos por la asociación natural de estos dos elementos, con la posibilidad de obtener el teluro como subproducto. Sonora (México), se caracteriza por ser una zona rica en teluros con más de treinta especies registradas. Este artículo describe las principales localizaciones en que se encuentran minerales de teluro en Sonora (México), señalando sus principales características, así como las especies hasta ahora registradas. Se analizan, además, las posibles rutas de extracción y recuperación acuosa de teluro, de acuerdo con la fisicoquímica de los sistemas teluro-metales preciosos.
Obtención de nanopartículas de hierro y de grafito en plasma de argón
Authors: Bica I. , Muscutari I.
Published: October 2010

Se presenta el equipo experimental ideado para obtener partículas de hierro y de grafito en plasma de argón, así como los mecanismos de formación de dichas partículas y los resultados experimentales alcanzados mediante la disociación de Fe(CO)5 y maleato de 2-etil-hexil-hierro por el chorro de plasma. Las dimensiones de las partículas metálicas obtenidas varían entre 30 y 200 Å, mientras que las de grafito van de 30 a 100 Å.
Observaciones microestructurales en el composite Al-SiC-15p obtenido por el procedimiento de compocolado
Authors: Manzano-Ramírez A. , Ruiz F. , Magallanes-Castañeda A.
Published: October 2010

El propósito del presente trabajo es estudiar el efecto de las variables del procedimiento de compocolado (compocasting), velocidad de agitación y fracción de sólido, sobre el atrapamiento mecánico o incorporación de partículas de SiC a la matriz de aluminio del composite Al-SiC-15p. Para ello, se variaron la velocidad de corte, γ, y la fracción de sólido fs, (γ= 27, 120 y 213 s-1 y fs = 0,3, 0,4 y 0,5, respectivamente). Se utilizó el microscopio de fuerza atómica (AFM) para observar la topografía del composite y de ello poder inferir, al menos cualitativamente, el grado de integración de las partículas de refuerzo en la matriz. Además, se emplearon las posibilidades de análisis del microscopio electrónico de barrido (SEM) para tratar de determinar la composición de la fase responsable de la adherencia matriz-partícula de refuerzo. Los resultados obtenidos en el AFM confirmaron que el atrapamiento de las partículas de refuerzo, cuando estas tienen morfología esferoidal, es más eficiente a altas fracciones de sólido (fs > 0,4) y elevadas velocidades de corte (γ > 120 s-1), mientras que a bajas fracciones de sólido (fs < 0,3) y bajas velocidades de corte (γ < 27 s-1) el atrapamiento es menos efectivo. Por otro lado, se presenta una evidencia cualitativa que ilustra el mecanismo de fragmentación dendrítica, consecuencia de la evolución de la estructura del sólido primario de dendrítica a globular. Finalmente, los resultados obtenidos con el SEM sugieren que la adherencia podría establecerse a través de la fase rica en silicio; sin embargo, debido al tamaño del haz de electrones, se considera que esta técnica de análisis no es la más adecuada.
Moldeo por inyección del acero rápido M2
Authors: Ruiz-Román J. M. , Candela N. , Velasco F.
Published: October 2010

Se estudia la viabilidad de la tecnología de Moldeo por Inyección de Polvos (MIM) en la fabricación con acero rápido M2 a fin de obtener componentes de este material de prestaciones superiores a las que se consiguen mediante métodos convencionales pulvimetalúrgicos. Los ensayos realizados se han dirigido a optimizar los parámetros de la eliminación del ligante y de la sinterización, con objeto de controlar el contenido de carbono y la densidad final de las piezas, así como evitar la aparición de los defectos típicos de esta tecnología.
Obtención de polvo de aluminio por atomización
Authors: Krivij N. , Suwardjo W. , Frades J. , Chacón T. , Cores A. , García L.
Published: October 2010

En una planta piloto de pulvimetalurgia se obtiene polvo de aluminio destinado a la fabricación de piezas sinterizadas. Se determina la distribución granulométrica y se realizan la caracterización tecnológica y el estudio morfométrico del polvo de aluminio. Se estudia la sinterabilidad del polvo de aluminio mediante la sinterización isotérmica de las muestras prensadas a diferentes temperaturas y tiempos de retención.
Tratamiento hidrometalúrgico de los polvos de fundición de cobre. Desarsenifícación de las disoluciones de lixiviación
Authors: Alguacil F. J. , Magne L. , Navarro P. , Simpson J.
Published: October 2010

Los polvos que se producen en los procesos de fundición de cobre contienen, junto a este metal, elemento a recuperar, una serie de metales (especialmente arsénico) considerados contaminantes. Se han propuesto diversas alternativas para el tratamiento de estos residuos metalúrgicos y entre estas la Hidrometalurgia presenta buenas perspectivas para su aplicación en este campo. En el presente trabajo se describen y evalúan una serie de procesos hidrometalúrgicos propuestos para el tratamiento de los polvos de fundición de cobre, así como distintas alternativas para la desarsenifícación de las disoluciones de lixiviación.
Competitividad cinética entre el ordenamiento y la segregación de soluto hacia las dislocaciones en Cu-20% at. Mn
Authors: Donoso E. , Varschavsky A.
Published: October 2010

Utilizando calorimetría diferencial de barrido (DSC), se efectuaron medidas energéticas asociadas con los diferentes eventos térmicos desarrollados durante el calentamiento lineal de Cu-20 % at. Mn, empleando materiales templados y trabajados en frío. Contrariamente a la situación observada en la aleación templada, en la cual se desarrolla orden disperso, en la aleación deformada tal proceso es inhibido por la segregación de átomos de soluto hacia las dislocaciones parciales. Se utilizó un modelo para calcular la energía que se genera durante el proceso de anclaje, con el objeto de determinar la densidad de dislocaciones a partir del efecto exotérmico designado como etapa 4. El valor calculado, el cual está en excelente concordancia con el obtenido a partir de expresiones que gobiernan la energía liberada que acompaña la recristalización, permite verificar, conjuntamente con medidas de microdureza y análisis cinético, que el primer efecto térmico observado en el material deformado efectivamente corresponde a un proceso de segregación de soluto.
Ajuste de las curvas tensión-deformación a alta temperatura de un acero microaleado Nb-Ti
Authors: Pol L. A. , Asensio J. , Pero-Sanz J. A.
Published: October 2010

Se ha realizado una serie de ensayos de compresión plana en caliente en muestras de un acero microaleado con niobio y titanio en una máquina Servotest, en probetas trapezoidales de aproximadamente 10 mm de espesor. Se efectuaron dos series de ensayos con dos velocidades de deformación, 5 y 15 s-1, y temperaturas de deformación entre 850 y 1.025 °C. Los datos experimentales fueron corregidos por rozamiento probeta-herramientas, ausencia de condiciones de deformación plana y aumento de la temperatura en la muestra debido a que la deformación no es estrictamente adiabática, para obtener las curvas isotermas equivalentes en tracción. Dichas curvas han sido modelizadas según dos tipos de ecuaciones constitutivas que caracterizan el proceso de ablandamiento que tiene lugar concurrente a la deformación. Se calculan los coeficientes de las mismas por desarrollo en serie de Taylor alrededor de un punto inicial próximo a la solución y posteriormente, por mínimos cuadrados, se compara con los valores experimentales para obtener un valor optimizado de dichos coeficientes, iterando hasta la convergencia.
Efecto en la microestructura y en la resistencia a la corrosión bajo tensión del calentamiento producido por la soldadura en la aleación AA7028
Authors: Calatayud A. , Ródenas M. , Ferrer C. , Amigó V. , Salvador M. D.
Published: October 2010

Se estudian los cambios en la microestructura y en la resistencia a la corrosión bajo tensión que sufre el material base (aleación de aluminio AA7028), debido a la soldadura. Se presta especial atención a la caracterización de la denominada "zona blanca". También se estudia la influencia que sobre la microestructura y las características de la zona afectada por el calor (ZAC) tiene el tiempo de espera entre el temple y el envejecimiento en un T73. Y por último, se analiza el efecto que sobre dicha zona tiene la aplicación de tratamientos térmicos posteriores al proceso de soldeo.
Evaluación de un inhibidor utilizado en soluciones acidas bajo condiciones hidrodinámicas controladas
Authors: Salinas-Bravo V. M. , González-Rodríguez J. G.
Published: October 2010

Utilizando el electrodo cilíndrico rotatorio y técnicas electroquímicas, se estudió la eficiencia de la protección contra la corrosión de un inhibidor comercial utilizado en soluciones de ácido clorhídrico con y sin adiciones de tiourea y bifluoruro de amonio. El fenómeno de la corrosión se investigó en condiciones hidrodinámicas controladas, seleccionadas para simular las que se establecen en una tubería a distintas velocidades de flujo. Se encontró que la corrosión del acero al carbono en soluciones de ácido clorhídrico con inhibidor de corrosión está controlada principalmente por activación, mientras que en soluciones acidas con inhibidor y adiciones de tiourea y bifluoruro de amonio está controlada principalmente por transferencia de masa. Por otra parte, la velocidad del flujo de las soluciones acidas afecta de -manera negativa a la eficiencia de protección del inhibidor estudiado en el intervalo de concentración de 0,2 a 1,0 %.
Aplicación de técnicas cinéticas no isotérmicas en la reducción de tres minerales de hierro de grado comercial
Authors: Bedolla E. , León C. A. , Aguilar E. A.
Published: October 2010

Se estudió el mecanismo de reducción en aglomerados de mineral de hierro mediante análisis termogravimétricos tanto isotérmicos como no isotérmicos, complementando el estudio por caracterización estructural de muestras parcial y completamente reducidas. Se estudiaron tres tipos de pelets hematíticos grado comercial. Los mecanismos de reducción se determinaron isotérmicamente y resultaron ser modelos de control por reacción química. La reducción no isotérmica se realizó en un TGA CAHN-171 de 600 a 1.000 °C a velocidad de calentamiento lineal de 4, 7 y 10 °C/min, en atmósferas reductoras de H2 (100 %) y H2-CO (95:5). Los parámetros cinéticos se evaluaron por las técnicas propuestas por Coats & Redfern, Dixit & Ray y Prakash & Ray. Se encontró que a menor velocidad de calentamiento, mayor es el grado de reducción no isotérmico y mayor la energía de activación del proceso. La energía de activación con la mezcla H2-CO, siempre fue mayor que con H2 puro.
Transferencia de calor en la colada continua de aceros. I parte. El molde
Authors: Cicutti C.
Published: October 2010

El molde de colada continua cumple la importante función de recibir el acero líquido y permitir que se desarrolle una capa solidificada uniforme y libre de defectos. En este trabajo se revisan los distintos mecanismos implicados en el proceso de transferencia de calor, desde el acero líquido hasta el agua de refrigeración del molde. Se analiza también el efecto de las distintas variables de funcionamiento en la extracción calórica producida y la relación entre el flujo global de calor y su distribución a lo largo del molde.
IL-32: A Host Proinflammatory Factor against Influenza Viral Replication Is Upregulated by Aberrant Epigenetic Modifications during Influenza A Virus Infection
Authors: Li Wei , Sun Wei , Liu Li , Yang Fang , Li Yongkui , Chen Yanni , Fang Jiali , Zhang Wenjing , Wu Jianguo , Zhu Ying
Published: October 2010

Our previous studies with clinical data analysis have shown that the proinflammatory factor IL-32 is activated in response to influenza virus infection. However, little is known about how influenza virus induces IL-32 production, and the role of IL-32 in the host immune responses during viral infection remains unclear. In this study, we show that IL-32 production is stimulated by influenza A virus or dsRNA in human PBMCs from healthy volunteers. We demonstrate that the NF-κB and CREB pathways play key roles in the activation of IL-32 production in response to influenza virus infection in A549 human lung epithelial cells. We then show that aberrant epigenetic modifications in the IL32 promoter are important in the transcriptional regulation of IL-32 expression. Interestingly, one CpG demethylation within the CREB binding site increases the binding of CREB to the promoter, which is followed by IL32 transcriptional activation in influenza A virus-infected cells. Overexpression assays combined with RNA interference show that DNA methyltransferases DNMT1 and DNMT3b are critical for IL32 promoter methylation and gene silencing before viral infection. We have demonstrated the anti-influenza virus function of IL-32. Assays for each of the six IL-32 isoforms (α, β, γ, δ, ε, and ζ) during influenza virus infection indicated that all the isoforms have antiviral activity, with different inhibitory rates, and that the effect of IL-32γ is strongest. Our results indicate that the elevated IL-32 levels triggered by influenza virus infection in turn hamper viral replication.
Hypoxia-Induced Mitogenic Factor (HIMF/FIZZ1/RELMα) Increases Lung Inflammation and Activates Pulmonary Microvascular Endothelial Cells via an IL-4–Dependent Mechanism
Authors: Yamaji-Kegan Kazuyo , Su Qingning , Angelini Daniel J. , Myers Allen C. , Cheadle Chris , Johns Roger A.
Published: October 2010

Hypoxia-induced mitogenic factor (HIMF), also known as found in inflammatory zone 1 and resistin-like molecule α, belongs to a novel class of cysteine-rich secreted proteins. It exhibits mitogenic and chemotactic properties during pulmonary hypertension-associated vascular remodeling, as well as fibrogenic properties during pulmonary fibrosis. HIMF expression in the lung was reported to be regulated by Th2 cytokines (IL-4 and IL-13) via the transcription factor STAT6 pathway in a bleomycin-induced pulmonary fibrosis model. However, in this study, we found that in the hypoxia-induced pulmonary hypertension model, lung HIMF expression is increased in IL-4 and STAT6 knockout (KO) mice to the same degree as in wild-type (WT) mice, suggesting that induction of HIMF expression does not require Th2 regulation in this model. We also found that HIMF-induced proliferative activity, hypertrophy, collagen, and extracellular matrix deposition in the pulmonary arteries are significantly less in IL-4 KO mice than in WT mice. In addition, HIMF-induced production of angiogenic factors/chemokines, such as vascular endothelial growth factor, MCP-1, and stromal-derived factor-1, in the lung resident cells, as well as macrophage infiltration, were significantly suppressed in the lungs of IL-4 KO mice. We also show that IL-4 was significantly increased in the lungs of HIMF-treated WT mice. Our in vitro studies using pulmonary microvascular endothelial cells revealed that HIMF stimulated cell proliferation, vascular endothelial growth factor expression, and MCP-1 production in a manner that is dependent on the IL-4/IL-4Rα system. These findings suggest that IL-4 signaling may play a significant role in HIMF-induced lung inflammation and vascular remodeling.
Cutting Edge: CD4 T Cells Generated from Encounter with Seasonal Influenza Viruses and Vaccines Have Broad Protein Specificity and Can Directly Recognize Naturally Generated Epitopes Derived from the Live Pandemic H1N1 Virus
Authors: Richards Katherine A. , Topham David , Chaves Francisco A. , Sant Andrea J.
Published: October 2010

The unexpected emergence of pandemic H1N1 influenza has generated significant interest in understanding immunological memory to influenza and how previous encounters with seasonal strains influence our ability to respond to novel strains. In this study, we evaluate the memory T cell repertoire in healthy adults to determine the abundance and protein specificity of influenza-reactive CD4 T cells, using an unbiased and empirical approach, and assess the ability of CD4 T cells to recognize epitopes naturally generated by infection with pandemic H1N1 virus. Our studies revealed that most individuals have abundant circulating CD4 T cells that recognize influenza-encoded proteins and that a strikingly large number of CD4 T cells can recognize autologous cells infected with live H1N1 virus. Collectively, our results indicate that a significant fraction of CD4 T cells generated from priming with seasonal virus and vaccines can be immediately mobilized upon infection with pandemic influenza strains derived from antigenic shift.
CXCR7 Protein Is Not Expressed on Human or Mouse Leukocytes
Authors: Berahovich Robert D. , Zabel Brian A. , Penfold Mark E. T. , Lewén Susanna , Wang Yu , Miao Zhenhua , Gan Lin , Pereda Jaime , Dias Jessica , Slukvin Igor I. , McGrath Kathleen E. , Jaen Juan C. , Schall Thomas J.
Published: October 2010

Since the discovery that CXCR7 binds to CXCL12/SDF-1α, the role of CXCR7 in CXCL12-mediated biological processes has been under intensive scrutiny. However, there is no consensus in the literature on the expression of CXCR7 protein by peripheral blood cells. In this study we analyzed human and mouse leukocytes and erythrocytes for CXCR7 protein expression, using a competitive CXCL12 binding assay as well as by flow cytometry and immunohistochemistry using multiple CXCR7 Abs. CXCR7−/− mice were used as negative controls. Together, these methods indicate that CXCR7 protein is not expressed by human peripheral blood T cells, B cells, NK cells, or monocytes, or by mouse peripheral blood leukocytes. CXCR7 protein is, however, expressed on mouse primitive erythroid cells, which supply oxygen to the embryo during early stages of development. These studies therefore suggest that, whereas CXCR7 protein is expressed by primitive RBCs during murine embryonic development, in adult mammals CXCR7 protein is not expressed by normal peripheral blood cells.
A Nonredundant Role for IL-21 Receptor Signaling in Plasma Cell Differentiation and Protective Type 2 Immunity against Gastrointestinal Helminth Infection
Authors: King Irah L. , Mohrs Katja , Mohrs Markus
Published: October 2010

Pathogen-specific Ab production following infection with the gut-dwelling roundworm Heligmosomoides polygyrus is critical for protective immunity against reinfection. However, the factors required for productive T cell–B cell interactions in the context of a type 2-dominated immune response are not well defined. In the present study, we identify IL-21R signaling as a critical factor in driving pathogen-specific plasma cell differentiation and protective immunity against H. polygyrus in mice. We show that B cells require direct IL-21R signals to differentiate into CD138+ plasma cells. In contrast, IL-21R signaling is dispensable for germinal center formation, isotype class switching, and Th2 and T follicular helper cell differentiation. Our studies demonstrate a selective role for IL-21 in plasma cell differentiation in the context of protective antiparasitic type 2 immunity.
Granulysin Production and Anticryptococcal Activity Is Dependent upon a Far Upstream Enhancer That Binds STAT5 in Human Peripheral Blood CD4+ T Cells
Authors: Xing Junji , Wu Fuqing , Wang Shuai , Krensky Alan M. , Mody Christopher H. , Zheng Chunfu
Published: October 2010

Previous studies have demonstrated that STAT5 is critical for expression of granulysin and antimicrobial activity. Because the signaling pathway and the resultant microbicidal activity are defective in HIV-infected patients, the mechanism by which STAT5 leads to granulysin expression is of great interest. In the current study, IL-2–stimulated CRL-2105 CD4+ T cells expressed granulysin and killed Cryptococcus neoformans similar to primary CD4+ T cells. The enhancer activity of the upstream element of the granulysin promoter was analyzed in primary CD4+ T cells and CRL-2105 T cells with a luciferase reporter assay, and a STAT5 binding site, 18,302 to 18,177 bp upstream of the transcription start site, was identified as an enhancer. Additionally, the enhancer functioned in the context of heterologous SV40 promoter irrespective of its transcriptional orientation. Chromatin immunoprecipitation and EMSAs demonstrated that the enhancer element bound STAT5 both in vivo and in vitro, and mutation of the STAT5 binding site abrogated its enhancer activity. Furthermore, overexpression of a dominant negative STAT5a abolished the enhancer activity of the STAT5 binding site and abrogated the anticryptococcal activity of IL-2–stimulated primary CD4+ T cells. Taken together, these data provide details about the complex regulation leading to granulysin expression and anticryptococcal activity in primary CD4+ T cells.
Disruption of Intestinal CD4+ T Cell Homeostasis Is a Key Marker of Systemic CD4+ T Cell Activation in HIV-Infected Individuals
Authors: Gordon Shari N. , Cervasi Barbara , Odorizzi Pamela , Silverman Randee , Aberra Faten , Ginsberg Gregory , Estes Jacob D. , Paiardini Mirko , Frank Ian , Silvestri Guido
Published: October 2010

HIV infection is associated with depletion of intestinal CD4+ T cells, resulting in mucosal immune dysfunction, microbial translocation, chronic immune activation, and progressive immunodeficiency. In this study, we examined HIV-infected individuals with active virus replication (n = 15), treated with antiretroviral therapy (n = 13), and healthy controls (n = 11) and conducted a comparative analysis of T cells derived from blood and four gastrointestinal (GI) sites (terminal ileum, right colon, left colon, and sigmoid colon). As expected, we found that HIV infection is associated with depletion of total CD4+ T cells as well as CD4+CCR5+ T cells in all GI sites, with higher levels of these cells found in ART-treated individuals than in those with active virus replication. While the levels of both CD4+ and CD8+ T cell proliferation were higher in the blood of untreated HIV-infected individuals, only CD4+ T cell proliferation was significantly increased in the gut of the same patients. We also noted that the levels of CD4+ T cells and the percentages of CD4+Ki67+ proliferating T cells are inversely correlated in both blood and intestinal tissues, thus suggesting that CD4+ T cell homeostasis is similarly affected by HIV infection in these distinct anatomic compartments. Importantly, the level of intestinal CD4+ T cells (both total and Th17 cells) was inversely correlated with the percentage of circulating CD4+Ki67+ T cells. Collectively, these data confirm that the GI tract is a key player in the immunopathogenesis of HIV infection, and they reveal a strong association between the destruction of intestinal CD4+ T cell homeostasis in the gut and the level of systemic CD4+ T cell activation.
Cutting Edge: Thymic NK Cells Develop Independently from T Cell Precursors
Authors: Ribeiro Vera S. G. , Hasan Milena , Wilson Anne , Boucontet Laurent , Pereira Pablo , Lesjean-Pottier Sarah , Satoh-Takayama Naoko , Di Santo James P. , Vosshenrich Christian A. J.
Published: October 2010

Although NK cells in the mouse are thought to develop in the bone marrow, a small population of NK cells in the thymus has been shown to derive from a GATA3-dependent pathway. Characteristically, thymic NK cells express CD127 and few Ly49 molecules and lack CD11b. Because these NK cells develop in the thymus, the question of their relationship to the T cell lineage has been raised. Using several different mouse models, we find that unlike T cells, thymic NK cells are not the progeny of Rorc-expressing progenitors and do not express Rag2 or rearrange the TCRγ locus. We further demonstrate that thymic NK cells develop independently of the Notch signaling pathway, supporting the idea that thymic NK cells represent bona fide NK cells that can develop independently of all T cell precursors.