Theoretical and experimental studies on the electronic, optical, and structural properties of poly-pyrrole-2-carboxylic acid films

A theoretical approach is used here to explain experimental results obtained from the electrosynthesis of polypyrrole-2-carboxylic acid (PPY-2-COOH) films in nonaqueous medium. An analysis of the Fukui function (reactivity index) indicates that the monomer (pyrrole-2-carboxylic acid, PY-2-COOH), and dimers and trimers are oxidized in the C4 or C5 positions of the heterocyclic ring of the PY-2-COOH structure. After calculating the heat of formation using semiempirical Austin Model 1 post-Hartree-Fock parameterization for dimer species, both C4 and C5 positions adjacent to the aromatic rings of PPY-2-COOH were considered the most susceptible ones to oxidative coupling reactions. The ZINDO-S/CI semiempirical method was used to simulate the electronic transitions typically seen in the UV-VIS-NIR range in monomer and oligomers with different conjugation lengths. The use of an electrochemical quartz crystal microbalance provides sufficient information to propose a polymerization mechanism of PY-2-COOH based on molecular modeling and experimental results.

Source of funding in experimental studies of mobile phone use on health: Update of systematic review

A previous review showed that among 59 studies published in 1995–2005, industry-funded studies were least likely to report effects of controlled exposure to mobile phone radiation on health-related outcomes. We updated literature searches in 2005–2009 and extracted data on funding, conflicts of interest and results. Of 75 additional studies 12% were industry-funded, 44% had public and 19% mixed funding; funding was unclear in 25%. Previous findings were confirmed: industry-sponsored studies were least likely to report results suggesting effects. Interestingly, the proportion of studies indicating effects declined in 1995–2009, regardless of funding source. Source of funding and conflicts of interest are important in this field of research.

Source of funding and results of studies of health effects of mobile phone use: systematic review of experimental studies

OBJECTIVES: There is concern regarding the possible health effects of cellular telephone use. We examined whether the source of funding of studies of the effects of low-level radiofrequency radiation is associated with the results of studies. We conducted a systematic review of studies of controlled exposure to radiofrequency radiation with health-related outcomes (electroencephalogram, cognitive or cardiovascular function, hormone levels, symptoms, and subjective well-being). DATA SOURCES: We searched EMBASE, Medline, and a specialist database in February 2005 and scrutinized reference lists from relevant publications. DATA EXTRACTION: Data on the source of funding, study design, methodologic quality, and other study characteristics were extracted. The primary outcome was the reporting of at least one statistically significant association between the exposure and a health-related outcome. Data were analyzed using logistic regression models. DATA SYNTHESIS: Of 59 studies, 12 (20%) were funded exclusively by the telecommunications industry, 11 (19%) were funded by public agencies or charities, 14 (24%) had mixed funding (including industry), and in 22 (37%) the source of funding was not reported. Studies funded exclusively by industry reported the largest number of outcomes, but were least likely to report a statistically significant result: The odds ratio was 0.11 (95% confidence interval, 0.02-0.78), compared with studies funded by public agencies or charities. This finding was not materially altered in analyses adjusted for the number of outcomes reported, study quality, and other factors. CONCLUSIONS: The interpretation of results from studies of health effects of radiofrequency radiation should take sponsorship into account.

Bacterial meningitis: insights into pathogenesis and evaluation of new treatment options: a perspective from experimental studies.

ABSTRACT  Bacterial meningitis is associated with high mortality and morbidity rates. Bacterial components induce an overshooting inflammatory reaction, eventually leading to brain damage. Pathological correlates of neurofunctional deficits include cortical necrosis, damage of the inner ear and hippocampal apoptosis. The hippocampal dentate gyrus is important for memory acquisition and harbors a neuronal stem cell niche, thus being potentially well equipped for regeneration. Adjuvant therapies aimed at decreasing the inflammatory reaction, for example, dexamethasone, and those protecting the brain from injury have been evaluated in animal models of the disease. They include nonbacteriolytic antibiotics (e.g., daptomycin), metalloproteinase inhibitors and modulators of the immunological response, for example, granulocyte colony-stimulating factor. Increasing research interest has recently been focused on interventions aimed at supporting regenerative processes.

Theoretical and experimental studies of linkage disequilibrium in human populations

Linkage disequilibrium (LD) is defined as the nonrandom association of alleles at two or more loci in a population and may be a useful tool in a diverse array of applications including disease gene mapping, elucidating the demographic history of populations, and testing hypotheses of human evolution. However, the successful application of LD-based approaches to pertinent genetic questions is hampered by a lack of understanding about the forces that mediate the genome-wide distribution of LD within and between human populations. Delineating the genomic patterns of LD is a complex task that will require interdisciplinary research that transcends traditional scientific boundaries. The research presented in this dissertation is predicated upon the need for interdisciplinary studies and both theoretical and experimental projects were pursued. In the theoretical studies, I have investigated the effect of genotyping errors and SNP identification strategies on estimates of LD. The primary importance of these two chapters is that they provide important insights and guidance for the design of future empirical LD studies. Furthermore, I analyzed the allele frequency distribution of 26,530 single nucleotide polymorphisms (SNPs) in three populations and generated the first-generation natural selection map of the human genome, which will be an important resource for explaining and understanding genomic patterns of LD. Finally, in the experimental study, I describe a novel and simple, low-cost, and high-throughput SNP genotyping method. The theoretical analyses and experimental tools developed in this dissertation will facilitate a more complete understanding of patterns of LD in human populations. ^

Numerical and Experimental Studies of Sail Aerodynamics

The purpose of this investigation was the determination of the aerodynamic performance of sails and gain knowledge of the phenomena involved in order to improve the aerody¬namic characteristics. In this research, the airflow around different sails in four scenarios was studied. The method to analyze these scenarios was the combination of numerical simulations and experimental tests by taking advantage of the best of each tool. Two different Com¬putational Fluid Dynamic codes were utilized: the ANSYS-CFX and the CD-Adapco’s STAR-CCM+. The experimental tests were conducted in the Atmospheric Boundary Layer Wind Tunnel at the Universidad de Granada (Spain), the Twisted Flow Wind Tunnel at the University of Auckland (New Zealand) and the A9 Wind Tunnel at the Universidad Polit´ecnica de Madrid (Spain). Through this research, it was found the three-dimensional effect of the mast on the aerodynamic performance of an IMS Class boat. The pressure distribution on a Transpac 52 Class mainsail was also determined. Moreover, the aerodynamic perfor¬mance of the 43ft and 60ft Dhow Classes was obtained. Finally, a feasibility study was conducted to use a structural wing in combination with conventional propulsions systems. The main conclusion was that this research clarified gaps on the knowledge of the aerodynamic performance of sails. Moreover, since commercial codes were not specifically designed to study sails, a procedure was developed. On the other hand, innovative experimental techniques were used and applied to model-scale sails. The achievements of this thesis are promising and some of the results are already in use by the industry on a daily basis. El propósito de este estudio era determinar el comportamiento aerodinámico de unas velas y mejorar el conocimiento de los fenómenos que suceden para optimizar las características aerodinámicas de dichas velas. En esta investigación se estudió el flujo de aire alrededor de diferentes velas en cuatro escenarios. El método para analizar estos escenarios fue la combinación de simulaciones numéricas y ensayos experimentales mediante el aprovechamiento de las ventajas de cada herramienta. Se utilizaron dos códigos de dinámica de fluidos computacional: el ANSYS-CFX y el STAR-CCM+ de la empresa CD-Adapco. Los ensayos experimentales se desarrollaron en el túnel de viento de capa límite de la Universidad de Granada (España), el túnel de viento de la Universidad de Auckland (Nueva Zelanda) y en el túnel A9 de la Universidad Politécnica de Madrid (España). Mediante esta investigación, se determinó el efecto tridimensional del mástil en un velero de la clase IMS. También se describió la distribución de presiones sobre una mayor de un Transpac 52. Además, se obtuvo el comportamiento aerodinámico de las clases 43ft y 60ft de los veleros Dhows. Finalmente, se llevó a cabo un estudio de viabilidad de la utilización de un ala estructural en combinación con sistemas de propulsión convencionales. La conclusión principal de esta investigación fue la capacidad de explicar ciertas lagunas en el conocimiento del comportamiento aerodinámico de las velas en diferentes escenarios. Además, dado que los códigos comerciales no están específicamente diseñados para el estudio de velas, se desarrolló un procedimiento a tal efecto. Por otro lado, se han utilizado innovadoras técnicas experimentales y se han aplicado a modelos de velas a escala. Los logros de esta investigación son prometedores y algunos de los resultados obtenidos ya están siendo utilizados por la industria en su día a día.

Experimental studies on transitional separated boundary layers

Separated transitional boundary layers appear on key aeronautical processes such as the flow around wings or turbomachinery blades. The aim of this thesis is the study of these flows in representative scenarios of technological applications, gaining knowledge about phenomenology and physical processes that occur there and, developing a simple model for scaling them. To achieve this goal, experimental measurements have been carried out in a low speed facility, ensuring the flow homogeneity and a low disturbances level such that unwanted transitional mechanisms are avoided. The studied boundary layers have been developed on a flat plate, by imposing a pressure gradient by means of contoured walls. They generate an initial acceleration region followed by a deceleration zone. The initial region is designed to obtain at the beginning of the deceleration the Blasius profile, characterized by its momentum thickness, and an edge boundary layer velocity, defining the problem characteristic velocity. The deceleration region is designed to obtain a linear evolution of the edge velocity, thereby defining the characteristic length of the problem. Several experimental techniques, both intrusive (hot wire anemometry, total pressure probes) as nonintrusive (PIV and LDV anemometry, high-speed filming), have been used in order to take advantage of each of them and allow cross-validation of the results. Once the boundary layer at the deceleration beginning has been characterized, ensuring the desired integral parameters and level of disturbance, the evolution of the laminar boundary layer up to the point of separation is studied. It has been compared with integral methods, and numerical simulations. In view of the results a new model for this evolution is proposed. Downstream from the separation, the flow near to the wall is configured as a shear layer that encloses low momentum recirculating fluid. The region where the shear layer remains laminar tends to be positioned to compensate the adverse pressure gradient associated with the imposed deceleration. Under these conditions, the momentum thickness remains almost constant. This laminar shear layer region extends up to where transitional phenomena appear, extension that scales with the momentum thickness at separation. These transitional phenomena are of inviscid type, similar to those found in free shear layers. The transitional region analysis begins with a study of the disturbances evolution in the linear growth region and the comparison of experimental results with a numerical model based on Linear Stability Theory for parallel flows and with data from other authors. The results’ coalescence for both the disturbances growth and the excited frequencies is stated. For the transition final stages the vorticity concentration into vortex blobs is found, analogously to what happens in free shear layers. Unlike these, the presence of the wall and the pressure gradient make the large scale structures to move towards the wall and quickly disappear under certain circumstances. In these cases, the recirculating flow is confined into a closed region saying the bubble is closed or the boundary layer reattaches. From the reattachment point, the fluid shows a configuration in the vicinity of the wall traditionally considered as turbulent. It has been observed that existing integral methods for turbulent boundary layers do not fit well to the experimental results, due to these methods being valid only for fully developed turbulent flow. Nevertheless, it has been found that downstream from the reattachment point the velocity profiles are self-similar, and a model has been proposed for the evolution of the integral parameters of the boundary layer in this region. Finally, the phenomenon known as bubble burst is analyzed. It has been checked the validity of existing models in literature and a new one is proposed. This phenomenon is blamed to the inability of the large scale structures formed after the transition to overcome with the adverse pressure gradient, move towards the wall and close the bubble. El estudio de capas límites transicionales con separación es de gran relevancia en distintas aplicaciones tecnológicas. Particularmente, en tecnología aeronáutica, aparecen en procesos claves, tales como el flujo alrededor de alas o álabes de turbomaquinaria. El objetivo de esta tesis es el estudio de estos flujos en situaciones representativas de las aplicaciones tecnológicas, ganando por un lado conocimiento sobre la fenomenología y los procesos físicos que aparecen y, por otra parte, desarrollando un modelo sencillo para el escalado de los mismos. Para conseguir este objetivo se han realizado ensayos en una instalación experimental de baja velocidad específicamente diseñada para asegurar un flujo homogéneo y con bajo nivel de perturbaciones, de modo que se evita el disparo de mecanismos transicionales no deseados. La capa límite bajo estudio se ha desarrollado sobre una placa plana, imponiendo un gradiente de presión a la misma por medio de paredes de geometría especificada. éstas generan una región inicial de aceleración seguida de una zona de deceleración. La región inicial se diseña para tener en al inicio de la deceleración un perfil de capa límite de Blasius, caracterizado por su espesor de cantidad de movimiento, y una cierta velocidad externa a la capa límite que se considera la velocidad característica del problema. La región de deceleración está concebida para que la variación de la velocidad externa a la capa límite sea lineal, definiendo de esta forma una longitud característica del problema. Los ensayos se han realizado explotando varias técnicas experimentales, tanto intrusivas (anemometría de hilo caliente, sondas de presión total) como no intrusivas (anemometrías láser y PIV, filmación de alta velocidad), de cara a aprovechar las ventajas de cada una de ellas y permitir validación cruzada de resultados entre las mismas. Caracterizada la capa límite al comienzo de la deceleración, y garantizados los parámetros integrales y niveles de perturbación deseados se procede al estudio de la zona de deceleración. Se presenta en la tesis un análisis de la evolución de la capa límite laminar desde el inicio de la misma hasta el punto de separación, comparando con métodos integrales, simulaciones numéricas, y proponiendo un nuevo modelo para esta evolución. Aguas abajo de la separación, el flujo en las proximidades de la pared se configura como una capa de cortadura que encierra una región de fluido recirculatorio de baja cantidad de movimiento. Se ha caracterizado la región en que dicha capa de cortadura permanece laminar, encontrando que se posiciona de modo que compensa el gradiente adverso de presión asociado a la deceleración de la corriente. En estas condiciones, el espesor de cantidad de movimiento permanece prácticamente constante y esta capa de cortadura laminar se extiende hasta que los fenómenos transicionales aparecen. Estos fenómenos son de tipo no viscoso, similares a los que aparecen en una capa de cortadura libre. El análisis de la región transicional comienza con un estudio de la evolución de las vii viii RESUMEN perturbaciones en la zona de crecimiento lineal de las mismas y la comparación de los resultados experimentales con un modelo numérico y con datos de otros autores. La coalescencia de los resultados tanto para el crecimiento de las perturbaciones como para las frecuencias excitadas queda demostrada. Para los estadios finales de la transición se observa la concentración de la vorticidad en torbellinos, de modo análogo a lo que ocurre en capas de cortadura libres. A diferencia de estas, la presencia de la pared y del gradiente de presión hace que, bajo ciertas condiciones, la gran escala se desplace hacia la pared y desaparezca rápidamente. En este caso el flujo recirculatorio queda confinado en una región cerrada y se habla de cierre de la burbuja o readherencia de la capa límite. A partir del punto de readherencia se tiene una configuración fluida en las proximidades de la pared que tradicionalmente se ha considerado turbulenta. Se ha observado que los métodos integrales existentes para capas límites turbulentas no ajustan bien a las medidas experimentales realizadas, hecho imputable a que no se obtiene en dicha región un flujo turbulento plenamente desarrollado. Se ha encontrado, sin embargo, que pasado el punto de readherencia los perfiles de velocidad próximos a la pared son autosemejantes entre sí y se ha propuesto un modelo para la evolución de los parámetros integrales de la capa límite en esta región. Finalmente, el fenómeno conocido como “estallido” de la burbuja se ha analizado. Se ha comprobado la validez de los modelos existentes en la literatura y se propone uno nuevo. Este fenómeno se achaca a la incapacidad de la gran estructura formada tras la transición para vencer el gradiente adverso de presión, desplazarse hacia la pared y cerrar la burbuja.

Experimental studies on control of oak wilt disease /

Cover title.

Field test evaluation of rear lighting deceleration signals: I - analytical and experimental studies. Interim report.

National Highway Traffic Safety Administration, Washington, D.C.

Basic experimental studies on boiling fluid flow and heat transfer at elevated pressures for month of ...

"Monthly progress report".

Two experimental studies of traffic law. Volume II: the effect of court appearance on traffic law violaters. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Experimental studies of the aerodynamics of ground effect machines.

"Task 9R99-01-005-02, contract DA44-177-TC-776."