CO2-driven ocean acidification alters and weakens integrity of the calcareous tubes produced by the serpulid tubeworm, Hydroides elegans

As a consequence of anthropogenic CO2-driven ocean acidification (OA), coastal waters are becoming increasingly challenging for calcifiers due to reductions in saturation states of calcium carbonate (CaCO3) minerals. The response of calcification rate is one of the most frequently investigated symptoms of OA. However, OA may also result in poor quality calcareous products through impaired calcification processes despite there being no observed change in calcification rate. The mineralogy and ultrastructure of the calcareous products under OA conditions may be altered, resulting in changes to the mechanical properties of calcified structures. Here, the warm water biofouling tubeworm, Hydroides elegans, was reared from larva to early juvenile stage at the aragonite saturation state (Omega A) for the current pCO2 level (ambient) and those predicted for the years 2050, 2100 and 2300. Composition, ultrastructure and mechanical strength of the calcareous tubes produced by those early juvenile tubeworms were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and nanoindentation. Juvenile tubes were composed primarily of the highly soluble CaCO3 mineral form, aragonite. Tubes produced in seawater with aragonite saturation states near or below one had significantly higher proportions of the crystalline precursor, amorphous calcium carbonate (ACC) and the calcite/aragonite ratio dramatically increased. These alterations in tube mineralogy resulted in a holistic deterioration of the tube hardness and elasticity. Thus, in conditions where Omega A is near or below one, the aragonite-producing juvenile tubeworms may no longer be able to maintain the integrity of their calcification products, and may result in reduced survivorship due to the weakened tube protection.

Photon Management Structures for Absorption Enhancement in Intermediate Band Solar Cells and Crystalline Silicon Solar Cells

El objetivo de la tesis es investigar los beneficios que el atrapamiento de la luz mediante fen��menos difractivos puede suponer para las c��lulas solares de silicio cristalino y las de banda intermedia. Ambos tipos de c��lulas adolecen de una insuficiente absorci��n de fotones en alguna regi��n del espectro solar. Las c��lulas solares de banda intermedia son te��ricamente capaces de alcanzar eficiencias mucho mayores que los dispositivos convencionales (con una sola banda energ��tica prohibida), pero los prototipos actuales se resienten de una absorci��n muy d��bil de los fotones con energ��as menores que la banda prohibida. Del mismo modo, las c��lulas solares de silicio cristalino absorben d��bilmente en el infrarrojo cercano debido al car��cter indirecto de su banda prohibida. Se ha prestado mucha atenci��n a este problema durante las ��ltimas d��cadas, de modo que todas las c��lulas solares de silicio cristalino comerciales incorporan alguna forma de atrapamiento de luz. Por razones de econom��a, en la industria se persigue el uso de obleas cada vez m��s delgadas, con lo que el atrapamiento de la luz adquiere m��s importancia. Por tanto aumenta el inter��s en las estructuras difractivas, ya que podr��an suponer una mejora sobre el estado del arte. Se comienza desarrollando un m��todo de c��lculo con el que simular c��lulas solares equipadas con redes de difracci��n. En este m��todo, la red de difracci��n se analiza en el ��mbito de la ��ptica f��sica, mediante an��lisis riguroso con ondas acopladas (rigorous coupled wave analysis), y el sustrato de la c��lula solar, ��pticamente grueso, se analiza en los t��rminos de la ��ptica geom��trica. El m��todo se ha implementado en ordenador y se ha visto que es eficiente y da resultados en buen acuerdo con m��todos diferentes descritos por otros autores. Utilizando el formalismo matricial as�� derivado, se calcula el l��mite te��rico superior para el aumento de la absorci��n en c��lulas solares mediante el uso de redes de difracci��n. Este l��mite se compara con el llamado l��mite lambertiano del atrapamiento de la luz y con el l��mite absoluto en sustratos gruesos. Se encuentra que las redes biperi��dicas (con geometr��a hexagonal o rectangular) pueden producir un atrapamiento mucho mejor que las redes uniperi��dicas. El l��mite superior depende mucho del periodo de la red. Para periodos grandes, las redes son en teor��a capaces de alcanzar el m��ximo atrapamiento, pero s��lo si las eficiencias de difracci��n tienen una forma peculiar que parece inalcanzable con las herramientas actuales de dise��o. Para periodos similares a la longitud de onda de la luz incidente, las redes de difracci��n pueden proporcionar atrapamiento por debajo del m��ximo te��rico pero por encima del l��mite Lambertiano, sin imponer requisitos irrealizables a la forma de las eficiencias de difracci��n y en un margen de longitudes de onda razonablemente amplio. El m��todo de c��lculo desarrollado se usa tambi��n para dise��ar y optimizar redes de difracci��n para el atrapamiento de la luz en c��lulas solares. La red propuesta consiste en un red hexagonal de pozos cil��ndricos excavados en la cara posterior del sustrato absorbente de la c��lula solar. La red se encapsula en una capa diel��ctrica y se cubre con un espejo posterior. Se simula esta estructura para una c��lula solar de silicio y para una de banda intermedia y puntos cu��nticos. Num��ricamente, se determinan los valores ��ptimos del periodo de la red y de la profundidad y las dimensiones laterales de los pozos para ambos tipos de c��lulas. Los valores se explican utilizando conceptos f��sicos sencillos, lo que nos permite extraer conclusiones generales que se pueden aplicar a c��lulas de otras tecnolog��as. Las texturas con redes de difracci��n se fabrican en sustratos de silicio cristalino mediante litograf��a por nanoimpresi��n y ataque con iones reactivos. De los c��lculos precedentes, se conoce el periodo ��ptimo de la red que se toma como una constante de dise��o. Los sustratos se procesan para obtener estructuras precursoras de c��lulas solares sobre las que se realizan medidas ��pticas. Las medidas de reflexi��n en funci��n de la longitud de onda confirman que las redes cuadradas biperi��dicas consiguen mejor atrapamiento que las uniperi��dicas. Las estructuras fabricadas se simulan con la herramienta de c��lculo descrita en los p��rrafos precedentes y se obtiene un buen acuerdo entre la medida y los resultados de la simulaci��n. ��sta revela que una fracci��n significativa de los fotones incidentes son absorbidos en el reflector posterior de aluminio, y por tanto desaprovechados, y que este efecto empeora por la rugosidad del espejo. Se desarrolla un m��todo alternativo para crear la capa diel��ctrica que consigue que el reflector se deposite sobre una superficie plana, encontr��ndose que en las muestras preparadas de esta manera la absorci��n par��sita en el espejo es menor. La siguiente tarea descrita en la tesis es el estudio de la absorci��n de fotones en puntos cu��nticos semiconductores. Con la aproximaci��n de masa efectiva, se calculan los niveles de energ��a de los estados confinados en puntos cu��nticos de InAs/GaAs. Se emplea un m��todo de una y de cuatro bandas para el c��lculo de la funci��n de onda de electrones y huecos, respectivamente; en el ��ltimo caso se utiliza un hamiltoniano emp��rico. La regla de oro de Fermi permite obtener la intensidad de las transiciones ��pticas entre los estados confinados. Se investiga el efecto de las dimensiones del punto cu��ntico en los niveles de energ��a y la intensidad de las transiciones y se obtiene que, al disminuir la anchura del punto cu��ntico respecto a su valor en los prototipos actuales, se puede conseguir una transici��n m��s intensa entre el nivel intermedio fundamental y la banda de conducci��n. Tomando como datos de partida los niveles de energ��a y las intensidades de las transiciones calculados como se ha explicado, se desarrolla un modelo de equilibrio o balance detallado realista para c��lulas solares de puntos cu��nticos. Con el modelo se calculan las diferentes corrientes debidas a transiciones ��pticas entre los numerosos niveles intermedios y las bandas de conducci��n y de valencia bajo ciertas condiciones. Se distingue de modelos de equilibrio detallado previos, usados para calcular l��mites de eficiencia, en que se adoptan suposiciones realistas sobre la absorci��n de fotones para cada transici��n. Con este modelo se reproducen datos publicados de eficiencias cu��nticas experimentales a diferentes temperaturas con un acuerdo muy bueno. Se muestra que el conocido fen��meno del escape t��rmico de los puntos cu��nticos es de naturaleza fot��nica; se debe a los fotones t��rmicos, que inducen transiciones entre los estados excitados que se encuentran escalonados en energ��a entre el estado intermedio fundamental y la banda de conducci��n. En el cap��tulo final, este modelo realista de equilibrio detallado se combina con el m��todo de simulaci��n de redes de difracci��n para predecir el efecto que tendr��a incorporar una red de difracci��n en una c��lula solar de banda intermedia y puntos cu��nticos. Se ha de optimizar cuidadosamente el periodo de la red para equilibrar el aumento de las diferentes transiciones intermedias, que tienen lugar en serie. Debido a que la absorci��n en los puntos cu��nticos es extremadamente d��bil, se deduce que el atrapamiento de la luz, por s�� solo, no es suficiente para conseguir corrientes apreciables a partir de fotones con energ��a menor que la banda prohibida en las c��lulas con puntos cu��nticos. Se requiere una combinaci��n del atrapamiento de la luz con un incremento de la densidad de puntos cu��nticos. En el l��mite radiativo y sin atrapamiento de la luz, se necesitar��a que el n��mero de puntos cu��nticos de una c��lula solar se multiplicara por 1000 para superar la eficiencia de una c��lula de referencia con una sola banda prohibida. En cambio, una c��lula con red de difracci��n precisar��a un incremento del n��mero de puntos en un factor 10 a 100, dependiendo del nivel de la absorci��n par��sita en el reflector posterior. Abstract The purpose of this thesis is to investigate the benefits that diffractive light trapping can offer to quantum dot intermediate band solar cells and crystalline silicon solar cells. Both solar cell technologies suffer from incomplete photon absorption in some part of the solar spectrum. Quantum dot intermediate band solar cells are theoretically capable of achieving much higher efficiencies than conventional single-gap devices. Present prototypes suffer from extremely weak absorption of subbandgap photons in the quantum dots. This problem has received little attention so far, yet it is a serious barrier to the technology approaching its theoretical efficiency limit. Crystalline silicon solar cells absorb weakly in the near infrared due to their indirect bandgap. This problem has received much attention over recent decades, and all commercial crystalline silicon solar cells employ some form of light trapping. With the industry moving toward thinner and thinner wafers, light trapping is becoming of greater importance and diffractive structures may offer an improvement over the state-of-the-art. We begin by constructing a computational method with which to simulate solar cells equipped with diffraction grating textures. The method employs a wave-optical treatment of the diffraction grating, via rigorous coupled wave analysis, with a geometric-optical treatment of the thick solar cell bulk. These are combined using a steady-state matrix formalism. The method has been implemented computationally, and is found to be efficient and to give results in good agreement with alternative methods from other authors. The theoretical upper limit to absorption enhancement in solar cells using diffractions gratings is calculated using the matrix formalism derived in the previous task. This limit is compared to the so-called Lambertian limit for light trapping with isotropic scatterers, and to the absolute upper limit to light trapping in bulk absorbers. It is found that bi-periodic gratings (square or hexagonal geometry) are capable of offering much better light trapping than uni-periodic line gratings. The upper limit depends strongly on the grating period. For large periods, diffraction gratings are theoretically able to offer light trapping at the absolute upper limit, but only if the scattering efficiencies have a particular form, which is deemed to be beyond present design capabilities. For periods similar to the incident wavelength, diffraction gratings can offer light trapping below the absolute limit but above the Lambertian limit without placing unrealistic demands on the exact form of the scattering efficiencies. This is possible for a reasonably broad wavelength range. The computational method is used to design and optimise diffraction gratings for light trapping in solar cells. The proposed diffraction grating consists of a hexagonal lattice of cylindrical wells etched into the rear of the bulk solar cell absorber. This is encapsulated in a dielectric buffer layer, and capped with a rear reflector. Simulations are made of this grating profile applied to a crystalline silicon solar cell and to a quantum dot intermediate band solar cell. The grating period, well depth, and lateral well dimensions are optimised numerically for both solar cell types. This yields the optimum parameters to be used in fabrication of grating equipped solar cells. The optimum parameters are explained using simple physical concepts, allowing us to make more general statements that can be applied to other solar cell technologies. Diffraction grating textures are fabricated on crystalline silicon substrates using nano-imprint lithography and reactive ion etching. The optimum grating period from the previous task has been used as a design parameter. The substrates have been processed into solar cell precursors for optical measurements. Reflection spectroscopy measurements confirm that bi-periodic square gratings offer better absorption enhancement than uni-periodic line gratings. The fabricated structures have been simulated with the previously developed computation tool, with good agreement between measurement and simulation results. The simulations reveal that a significant amount of the incident photons are absorbed parasitically in the rear reflector, and that this is exacerbated by the non-planarity of the rear reflector. An alternative method of depositing the dielectric buffer layer was developed, which leaves a planar surface onto which the reflector is deposited. It was found that samples prepared in this way suffered less from parasitic reflector absorption. The next task described in the thesis is the study of photon absorption in semiconductor quantum dots. The bound-state energy levels of in InAs/GaAs quantum dots is calculated using the effective mass approximation. A one- and four- band method is applied to the calculation of electron and hole wavefunctions respectively, with an empirical Hamiltonian being employed in the latter case. The strength of optical transitions between the bound states is calculated using the Fermi golden rule. The effect of the quantum dot dimensions on the energy levels and transition strengths is investigated. It is found that a strong direct transition between the ground intermediate state and the conduction band can be promoted by decreasing the quantum dot width from its value in present prototypes. This has the added benefit of reducing the ladder of excited states between the ground state and the conduction band, which may help to reduce thermal escape of electrons from quantum dots: an undesirable phenomenon from the point of view of the open circuit voltage of an intermediate band solar cell. A realistic detailed balance model is developed for quantum dot solar cells, which uses as input the energy levels and transition strengths calculated in the previous task. The model calculates the transition currents between the many intermediate levels and the valence and conduction bands under a given set of conditions. It is distinct from previous idealised detailed balance models, which are used to calculate limiting efficiencies, since it makes realistic assumptions about photon absorption by each transition. The model is used to reproduce published experimental quantum efficiency results at different temperatures, with quite good agreement. The much-studied phenomenon of thermal escape from quantum dots is found to be photonic; it is due to thermal photons, which induce transitions between the ladder of excited states between the ground intermediate state and the conduction band. In the final chapter, the realistic detailed balance model is combined with the diffraction grating simulation method to predict the effect of incorporating a diffraction grating into a quantum dot intermediate band solar cell. Careful optimisation of the grating period is made to balance the enhancement given to the different intermediate transitions, which occur in series. Due to the extremely weak absorption in the quantum dots, it is found that light trapping alone is not sufficient to achieve high subbandgap currents in quantum dot solar cells. Instead, a combination of light trapping and increased quantum dot density is required. Within the radiative limit, a quantum dot solar cell with no light trapping requires a 1000 fold increase in the number of quantum dots to supersede the efficiency of a single-gap reference cell. A quantum dot solar cell equipped with a diffraction grating requires between a 10 and 100 fold increase in the number of quantum dots, depending on the level of parasitic absorption in the rear reflector.

Relationship among slurry characteristics and gaseous emissions at different types of commercial Spanish pig farms

This study aimed to analyse several factors of variation of slurry composition and to establish prediction equations for potential methane (CH4) and ammonia (NH3) emissions. Seventy-nine feed and slurry samples were collected at two seasons (summer and winter) from commercial pig farms sited at two Spanish regions (Centre and Mediterranean). Nursery, growing-fattening, gestating and lactating facilities were sampled. Feed and slurry composition were determined, and potential CH4 and NH3 emissions measured at laboratory. Feed nutrient contents were used as covariates in the analysis. Near infrared reflectance spectroscopy (NIRS) was evaluated as a predicting tool for slurry composition and potential gaseous emissions. A wide variability was found both in feed and slurry composition. Mediterranean farms had a higher pH (p<0.001) and ash (p=0.02) concentration than those located at the Centre of Spain. Also, type of farm affected ether extract content of the slurry (p=0.02), with highest values obtained for the youngest animal facilities. Results suggested a buffer effect of dietary fibre on slurry pH and a direct relationship (p<0.05) with fibre constituents of manure. Dietary protein content did not affect slurry nitrogen content but decreased (p=0.003) total and volatile solids concentration. Prediction models of potential NH3 emissions (R2=0.89) and CH4 yield (R2=0.61) were obtained from slurry composition. Predictions from NIRS showed a high accuracy for most slurry constituents (R2>0.90) and similar accuracy of prediction of potential NH3 and CH4 emissions (R2=0.84 and 0.68, respectively) to models using slurry characteristics, which can be of interest to estimate emissions from commercial farms and establish mitigation strategies or optimize biogas production.

Ammonia and methane gas emissions from pig slurry: variability induced through feeding strategies

Esta Tesis doctoral fue desarrollada para estudiar las emisiones de amoniaco (NH3) y metano (CH4) en purines de cerdos, y los efectos ocasionados por cambios en la formulaci��n de la dieta. Con este prop��sito, fueron llevados a cabo tres estudios. El experimento 1 fue realizado con el objetivo de analizar los factores de variaci��n de la composici��n de purines y establecer ecuaciones de predicci��n para emisiones potenciales de NH3 y CH4. Fueron recogidas setenta y nueve muestras de piensos y purines durante dos estaciones del a��o (verano y invierno) de granjas comerciales situadas en dos regiones de Espa��a (Centro y Mediterr��neo). Se muestrearon granjas de gestaci��n, maternidad, lactaci��n y cebo. Se determin�� la composici��n de piensos y purines, y la emisi��n potencial de NH3 y CH4. El contenido de nutrientes de los piensos fue usado como covariable en el an��lisis. La espectroscopia de reflectancia del infrarrojo cercano (NIRS) se evalu�� como herramienta de predicci��n de la composici��n y potencial emisi��n de gases del pur��n. Se encontr�� una amplia variabilidad en la composici��n de piensos y purines. Las granjas del Mediterr��neo ten��an mayor pH (P<0,001) y concentraci��n de cenizas (P =0,02) en el pur��n que las del Centro. El tipo de granja tambi��n afect�� al contenido de extracto et��reo (EE) del pur��n (P =0,02), observando los valores m��s elevados en las instalaciones de animales j��venes. Los resultados sugieren un efecto tamp��n de la fibra de la dieta en el pH del pur��n y una relaci��n directa (P<0,05) con el contenido de fibra fecal. El contenido de prote��na del pienso no afect�� al contenido de nitr��geno del pur��n, pero disminuy�� (P=0,003) la concentraci��n de s��lidos totales (ST) y de s��lidos vol��tiles (SV). Se obtuvieron modelos de predicci��n de la emisi��n potencial de NH3 (R2=0,89) y CH4 (R2=0,61) partir de la composici��n del pur��n. Los espectros NIRS mostraron una buena precisi��n para la estimaci��n de la mayor parte de los constituyentes, con coeficientes de determinaci��n de validaci��n cruzada (R2cv) superiores a 0,90, as�� como para la predicci��n del potencial de emisiones de NH3 y CH4 (R2cv=0,84 y 0,68, respectivamente). El experimento 2 fue realizado para investigar los efectos del nivel de inclusi��n de dos fuentes de sub-productos fibrosos: pulpa de naranja (PN) y pulpa de algarroba (PA), en dietas iso-fibrosas de cerdos de cebo, sobre la composici��n del pur��n y las emisiones potenciales de NH3 y CH4. Treinta cerdos (85,4��12,3 kg) fueron alimentados con cinco dietas iso-nutritivas: control comercial trigo/cebada (C) y cuatro dietas experimentales incluyendo las dos fuentes de sub-productos a dos niveles (75 y 150 g/kg) en una estructura 2 �� 2 factorial. Despu��s de 14 d��as de periodo de adaptaci��n, heces y orina fueron recogidas separadamente durante 7 d��as para medir la digestibilidad de los nutrientes y el nitr��geno (N) excretado (6 r��plicas por dieta) en cerdos alojados individualmente en jaulas metab��licas. Las emisiones de NH3 y CH4 fueron medidas despu��s de la recogida de los pur��nes durante 11 y 100 d��as respectivamente. La fuente y el nivel de subproductos fibrosos afect�� a la eficiencia digestiva de diferentes formas, ya que los coeficientes de digestibilidad total aparente (CDTA) para la materia seca (MS), materia org��nica (MO), fracciones fibrosas y energ��a bruta (EB) aumentaron con la PN pero disminuyeron con la inclusi��n de PA (P<0,05). El CDTA de prote��na bruta (PB) disminuy�� con la inclusi��n de las dos fuentes de fibra, siendo m��s bajo al mayor nivel de inclusi��n. La concentraci��n fecal de fracciones fibrosas aument�� (P<0,05) con el nivel de inclusi��n de PA pero disminuy�� con el de PN (P<0,01). El nivel m��s alto de las dos fuentes de fibra en el pienso aument�� (P<0,02) el contenido de PB fecal pero disminuy�� el contenido de N de la orina (de 205 para 168 g/kg MS, P<0,05) en todas las dietas suplementadas comparadas con la dieta C. Adicionalmente, las proporciones de nitr��geno indigerido, nitr��geno soluble en agua, nitr��geno bacteriano y end��geno excretado en heces no fueron afectados por los tratamientos. Las caracter��sticas iniciales del pur��n no difirieron entre las diferentes fuentes y niveles de fibra, excepto para el pH que disminuy�� con la inclusi��n de altos niveles de sub-productos. La emisi��n de NH3 por kg de pur��n fue m��s baja en todas las dietas suplementadas con fibras que en la dieta C (2,44 vs.1,81g de promedio, P<0,05). Adem��s, purines de dietas suplementadas con alto nivel de sub-productos tendieron (P<0,06) a emitir menos NH3 por kg de nitr��geno total y mostraron un potencial m��s bajo para emitir CH4, independientemente de la fuente de fibra. El experimento 3 investig�� los efectos de la fuente de prote��na en dietas pr��cticas. Tres piensos experimentales fueron dise��ados para sustituir una mescla de harina y cascarilla de soja (SOJ) por harina de girasol (GIR) o por DDGS del trigo (DDGST). La proporci��n de otros ingredientes fue modificada para mantener los contenidos de nutrientes similares a trav��s de las dietas. El cambio en la fuente de prote��na dio lugar a diferencias en el contenido de fibra neutro detergente ligada a prote��na bruta (FNDPB), fibra soluble (FS) y lignina ��cido detergente (LAD) en la dieta. Veinticuatro cerdos (ocho por dieta), con 52,3 o 60,8 kg en la primera y segunda tanda respectivamente, fueron alojados individualmente en jaulas metab��licas. Durante un periodo de 7 d��as fue determinado el balance de MS, el CDTA de los nutrientes y la composici��n de heces y orina. Se realiz�� el mismo procedimiento del experimento 2 para medir las emisiones de NH3 y CH4 de los purines de cada animal. Ni la ingesti��n de MS ni el CDTA de la MS o de la energ��a fueron diferentes entre las dietas experimentales, pero el tipo de pienso afect�� (P<0.001) la digestibilidad de la PB, que fue mayor para GIR (0,846) que para SOJ (0,775), mientras que la dieta DDGST mostr�� un valor intermedio (0,794). La concentraci��n fecal de PB fue por tanto influenciada (P<0,001) por el tratamiento, observ��ndose la menor concentraci��n de PB en la dieta GIR y la mayor en la dieta SOJ. La proporci��n de N excretado en orina o heces disminuy�� de 1,63 en la dieta GIR hasta 0,650 en la dieta SOJ, como consecuencia de perdidas m��s bajas en orina y m��s altas en heces, con todas las fracciones de nitr��geno fecales creciendo en paralelo a la excreci��n total. Este resultado fue paralelo a una disminuci��n de la emisi��n potencial de NH3 (g/kg pur��n) en la dieta SOJ con respecto a la dieta GIR (desde 1,82 a 1,12, P<0,05), dando valores intermedios (1,58) para los purines de la dieta DDGST. Por otro lado, el CDTA de la FS y de la fibra neutro detergente (FND) fueron afectados (P<0,001 y 0,002, respectivamente) por el tipo de dieta, siendo m��s bajas en la dieta GIR que en la dieta SOJ; adem��s, se observ�� un contenido m��s alto de FND (491 vs. 361g/kg) en la MS fecal para la dieta GIR que en la dieta SOJ, presentando la dieta DDGST valores intermedios. El grado de lignificaci��n de la FND (FAD/FND x 100) de las heces disminuy�� en el orden GIR>DDGST>SOJ (desde 0,171 hasta 0,109 y 0,086, respectivamente) en paralelo a la disminuci��n del potencial de emisi��n de CH4 por g de SV del pur��n (desde 301 a 269 y 256 mL, respectivamente). Todos los purines obtenidos en estos tres experimentos y Antezana et al. (2015) fueron usados para desarrollar nuevas calibraciones con la tecnolog��a NIRS, para predecir la composici��n del pur��n y el potencial de las emisiones de gases. Se observ�� una buena precisi��n (R2cv superior a 0,92) de las calibraciones cuando muestras de los ensayos controlados (2, 3 y Antezana et al., 2015) fueron a��adidas, aumentando el rango de variaci��n. Una menor exactitud fue observada para TAN y emisiones de NH3 y CH4, lo que podr��a explicarse por una menor homogeneidad en la distribuci��n de las muestras cuando se ampl��a el rango de variaci��n del estudio. ABSTRACT This PhD thesis was developed to study the emissions of ammonia (NH3) and methane (CH4) from pig slurry and the effects caused by changes on diet formulation. For these proposes three studies were conducted. Experiment 1 aimed to analyse several factors of variation of slurry composition and to establish prediction equations for potential CH4 and NH3 emissions. Seventy-nine feed and slurry samples were collected at two seasons (summer and winter) from commercial pig farms sited at two Spanish regions (Centre and Mediterranean). Nursery, growing-fattening, gestating and lactating facilities were sampled. Feed and slurry composition were determined, and potential CH4 and NH3 emissions measured. Feed nutrient contents were used as covariates in the analysis. Near infrared reflectance spectroscopy (NIRS) was evaluated as a predicting tool for slurry composition and potential gaseous emissions. A wide variability was found both in feed and slurry composition. Mediterranean farms had a higher pH (P<0.001) and ash (P=0.02) concentration than those located at the centre of Spain. Also, type of farm affected ether extract (EE) content of the slurry (P=0.02), with highest values obtained for the youngest animal facilities. Results suggested a buffer effect of dietary fibre on slurry pH and a direct relationship (P<0.05) with fibre constituents of manure. Dietary protein content did not affect slurry nitrogen content (N) but decreased (P=0.003) in total solid (TS) and volatile solids (VS) concentration. Prediction models of potential NH3 emissions (R2=0.89) and biochemical CH4 potential (B0) (R2=0.61) were obtained from slurry composition. Predictions from NIRS showed a high accuracy for most slurry constituents with coefficient of determination of cross validation (R2cv) above 0.90 and a similar accuracy of prediction of potential NH3 and CH4 emissions (R2cv=0.84 and 0.68, respectively) thus models based on slurry composition from commercial farms. Experiment 2 was conducted to investigate the effects of increasing the level of two sources of fibrous by-products, orange pulp (OP) and carob meal (CM), in iso-fibrous diets for growing-finishing pig, slurry composition and potential NH3 and CH4 emissions. Thirty pigs (85.4��12.3 kg) were fed five iso-nutritive diets: a commercial control wheat/barley (C) and four experimental diets including two sources of fibrous by-products OP and CM and two dietary levels (75 and 150 g/kg) in a 2 �� 2 factorial arrangement. After a 14-day adaptation period, faeces and urine were collected separately for 7 days to measure nutrient digestibility and the excretory patterns of N from pigs (6 replicates per diet) housed individually in metabolic pens. For each animal, the derived NH3 and CH4 emissions were measured in samples of slurry over an 11 and 100-day storage periods, respectively. Source and level of the fibrous by-products affected digestion efficiency in a different way as the coefficients of total tract apparent digestibility (CTTAD) for dry matter (DM), organic matter (OM), fibre fractions and gross energy (GE) increased with OP but decreased with CM (P<0.05). Crude protein CTTAD decreased with the inclusion of both sources of fibre, being lower at the highest dietary level. Faecal concentration of fibre fractions increased (P<0.05) with the level of inclusion of CM but decreased with that of OP (P<0.01). High dietary level for both sources of fibre increased (P<0.02) CP faecal content but urine N content decreased (from 205 to 168 g/kg DM, P<0.05) in all the fibre-supplemented compared to C diet. Additionally, the proportions of undigested dietary, water soluble, and bacterial and endogenous debris of faecal N excretion were not affected by treatments. The initial slurry characteristics did not differ among different fibre sources and dietary levels, except pH, which decreased at the highest by-product inclusion levels. Ammonia emission per kg of slurry was lower in all the fibre-supplemented diets than in C diet (2.44 vs. 1.81g as average, P<0.05). Additionally, slurries from the highest dietary level of by-products tended (P<0.06) to emit less NH3 per kg of initial total Kjeldahl nitrogen (TKN) and showed a lower biochemical CH4 potential , independently of the fibre source. Experiment 3 investigated the effects of protein source in practical diets. Three experimental feeds were designed to substitute a mixture of soybean meal and soybean hulls (SB diet) with sunflower meal (SFM) or wheat DDGS (WDDGS). The proportion of other ingredients was also modified in order to maintain similar nutrient contents across diets. Changes in protein source led to differences in dietary content of neutral detergent insoluble crude protein (NDICP), soluble fibre (SF) and acid detergent lignin (ADL). Twenty-four pigs (eight per diet), weighing 52.3 or 60.8 kg at the first and second batch respectively, were housed individually in metabolic pens to determine during a 7-day period DM balance, CTTAD of nutrients, and faecal and urine composition. Representative slurry samples from each animal were used to measure NH3 and CH4 emissions over an 11 and or 100-day storage period, respectively. Neither DM intake, nor DM or energy CTTAD differed among experimental diets, but type of feed affected (P<0.001) CP digestibility, which was highest for SFM (0.846) than for SB (0.775) diet, with WDDGS-based diet giving an intermediate value (0.794). Faecal DM composition was influenced (P<0.001) accordingly, with the lowest CP concentration found for diet SFM and the highest for SB. The ratio of N excreted in urine or faeces decreased from SFM (1.63) to SB diet (0.650), as a consequence of both lower urine and higher faecal losses, with all the faecal N fractions increasing in parallel to total excretion. This result was parallel to a decrease of potential NH3 emission (g/kg slurry) in diet SB with respect to diet SFM (from 1.82 to 1.12, P<0.05), giving slurry from WDDGS-based diet an intermediate value (1.58). Otherwise, SF and insoluble neutral detergent fibre (NDF) CTTAD were affected (P<0.001 and P=0.002, respectively) by type of diet, being lower for SFM than in SB-diet; besides, a higher content of NDF (491 vs. 361 g/kg) in faecal DM was observed for SFM with respect to SB based diet, with WDDGS diet being intermediate. Degree of lignification of NDF (ADL/NDF x 100) of faeces decreased in the order SFM>WDDGS>SB (from 0.171 to 0.109 and 0.086, respectively) in parallel to a decrease of biochemical CH4 potential per g of VS of slurry (from 301 to 269 and 256 ml, respectively). All slurry samples obtained from these three experiments and Antezana et al. (2015) were used to develop new calibrations with NIRS technology, to predict the slurry composition and potential gaseous emissions of samples with greater variability in comparison to experiment 1. Better accuracy (R2cv above 0.92) was observed for calibrations when samples from controlled trials experiments (2, 3 and Antezana et al., 2015) were included, increasing the range of variation. A lower accuracy was observed for TAN, NH3 and CH4 gaseous emissions, which might be explained by the less homogeneous distribution with a wider range of data.

Detection of a Yb3+ binding site in regenerated bacteriorhodopsin that is coordinated with the protein and phospholipid head���groups

Near infrared Yb3+ vibronic sideband spectroscopy was used to characterize specific lanthanide binding sites in bacteriorhodopsin (bR) and retinal free bacteriorhodopsin (bO). The VSB spectra for deionized bO regenerated with a ratio of 1:1 and 2:1 ion to bO are identical. Application of a two-dimensional anti-correlation technique suggests that only a single Yb3+ site is observed. The Yb3+ binding site in bO is observed to consist of PO2��� groups and carboxylic acid groups, both of which are bound in a bidentate manner. An additional contribution most likely arising from a phenolic group is also observed. This implies that the ligands for the observed single binding site are the lipid head groups and amino acid residues. The vibronic sidebands of Yb3+ in deionized bR regenerated at a ratio of 2:1 ion to bR are essentially identical to those in bO. The other high-affinity binding site is thus either not evident or its fluorescence is quenched. A discussion is given on the difference in binding of Ca2+ (or Mg2+) and lanthanides in phospholipid membrane proteins.

Data reduction pipeline for emir, the near-IR multi-object spectrograph for GTC

EMIR (Balcells et al. 2000) is a near-infrared wide-field camera and multi-object spectrograph being built for the GTC. The Data Reduction Pipeline (DRP) will be optimized for handling and reducing near-infrared data acquired with EMIR.

Estudo comparativo de t��cnicas num��ricas de invers��o para obten����o de distribui����o de tamanho de gotas em emuls��es.

O desenvolvimento de algoritmos computacionais para a obten����o de distribui����es de tamanho de part��cula em dispers��es e que utilizam dados espectrosc��picos em tempo real e in-line a partir de sensores permitir�� uma variedade de aplica����es, como o monitoramento de propriedades em fluidos de corte industriais, acompanhamento de processos de polimeriza����o, tratamento de efluentes e sensoriamento atmosf��rico. O presente estudo tem como objetivo a implementa����o e compara����o de t��cnicas para resolu����o de problemas de invers��o, desenvolvendo algoritmos que forne��am distribui����o de tamanho de part��culas em dispers��es a partir de dados de espectroscopia UV-Vis-Nir (Ultravioleta, Vis��vel e Infravermelho pr��ximo). Foram implementadas quatro t��cnicas, sendo uma delas um m��todo alternativo sem a presen��a de etapas de invers��o. Os m��todos que utilizaram alguma t��cnica de invers��o evidenciaram a dificuldade em se obter distribui����es de tamanho de gotas (DTG) de boa qualidade, enquanto o m��todo alternativo foi aquele que se mostrou mais eficiente e confi��vel. Este estudo �� parte de um programa cooperativo entre a Universidade de S��o Paulo e a Universidade de Bremen chamado programa BRAGECRIM (Brazilian German Cooperative Research Initiative in Manufacturing) e �� financiado pela FAPESP, CAPES, FINEP e CNPq (Brasil) e DFG (Alemanha).

Estudo do processo de absor����o e dessor����o de CO2 na solu����o aquosa de metildietanolamina e piperazina.

Estudou-se o processo de absor����o e dessor����o de CO2 em solu����o aquosa da mistura de metildietanolamina (MDEA) e piperazina (PZ). Os ensaios de absor����o foram realizados numa coluna de parede molhada com promotor de pel��cula, e, os ensaios de dessor����o num sistema de semibatelada, ambos em escala de laborat��rio. Os testes experimentais de absor����o foram realizados a 298 K e press��o atmosf��rica, com vaz��o de g��s (CO2 e ar atmosf��rico) de 2,2.10-4 m3 s-1 e as seguintes vaz��es de l��quido: 1,0.10-6; 1,3.10-6 e 1,7.10-6 m3 s-1. O sistema de absor����o foi caracterizado atrav��s da determina����o da ��rea interfacial, a, o coeficiente volum��trico de transfer��ncia de massa, kGa, e o coeficiente volum��trico global m��dio de transfer��ncia de massa, KGa. No caso dos ensaios de dessor����o, estes foram realizados nas temperaturas de 353, 363 e 368 K, onde empregou-se uma solu����o carbonatada de 10% PZ-20% MDEA e uma corrente de ar atmosf��rico nas vaz��es de 1,1.10-5 m3 s-1 e 2,7.10-5 m3 s-1. Este sistema foi caracterizado atrav��s da determina����o do coeficiente volum��trico global de transfer��ncia de massa, KLa. Os resultados experimentais da ��rea interfacial mostram que este �� fun����o da vaz��o do l��quido, sugerindo uma maior ��rea de irriga����o como o aumento desta, onde teve-se uma maior ��rea de transfer��ncia de massa. O resultado do par��metro, KGa, indica uma depend��ncia da vaz��o de l��quido, a qual est�� associada �� varia����o da ��rea interfacial e �� depend��ncia do par��metro KG com o perfil das concentra����es da MDEA e PZ ao longo da coluna. A partir da teoria do duplo filme e pelo conhecimento dos par��metros KGa, a e kGa, estimou-se um par��metro cin��tico-difusivo associado �� fase l��quida, (( ) ) . Os resultados experimentais mostram que esse par��metro varia pouco com a vaz��o de l��quido, indicando tratar-se de um processo independente da hidrodin��mica do l��quido, caracter��stico de sistemas com rea����o r��pida. A concentra����o das aminas e carbamatos, nos ensaios de absor����o e dessor����o, foi determinada atrav��s dos modelos de calibra����o obtidas pela t��cnica de espectroscopia no infravermelho. Nos ensaios de absor����o, foram observados que a concentra����o de PZ teve uma varia����o consider��vel (4 a 5% massa massa-1), entanto que a de MDEA variou pouco (0,3 a 0,5% massa massa-1), sugerindo que o processo de absor����o de CO2 na mistura MDEA-PZ �� controlado principalmente pela PZ, e sup��e-se que a MDEA tem um papel de receptor de pr��tons procedentes da rea����o entre a PZ e o CO2. Nos ensaios de dessor����o, observou-se que esse processo �� afetado pela temperatura, sendo que, em temperaturas perto da ebuli����o (372 K), a taxa de dessor����o de CO2 �� maior do que em temperaturas menores, em certa forma �� devido �� depend��ncia da velocidade de rea����o qu��mica com a temperatura. Os resultados do par��metro KLa indicam que este diminui em fun����o da concentra����o de carbamato de PZ (por exemplo, na temperatura de 368 K, de 7,5.10-4 a 1,0.10-4 s-1), devido a que este componente �� decomposto em altas temperaturas gerando o CO2 e as aminas, sugerindo uma diminui����o na velocidade de dessor����o de CO2. Assim tamb��m, os resultados experimentais do par��metro KLa indicam que este aumenta ligeiramente com a vaz��o do g��s.

An obscured cluster associated with the H���II region RCW173

Context. The discovery of several clusters of red supergiants towards l = 24�����30�� has triggered interest in this area of the Galactic plane, where lines of sight are very complex and previous explorations of the stellar content were very preliminary. Aims. We attempt to characterise the stellar population associated with the H���ii region RCW 173 (=Sh2-60), located at, as previous studies have suggested that this population could be beyond the Sagittarius arm. Methods. We obtained UBV photometry of a stellar field to the south of the brightest part of RCW 173, as well as spectroscopy of about twenty stars in the area. We combined our new data with archival 2MASS near-infrared photometry and Spitzer/GLIMPSE imaging and photometry, to achieve a more accurate characterisation of the stellar sources and the associated cloud. Results. We find a significant population of early-type stars located at d = 3.0 kpc, in good agreement with the ���near��� dynamical distance to the H���ii region. This population should be located at the near intersection of the Scutum-Crux arm. A luminous O7���II star is likely to be the main source of ionisation. Many stars are concentrated around the bright nebulosity, where GLIMPSE images in the mid infrared show the presence of a bubble of excited material surrounding a cavity that coincides spatially with a number of B0-1���V stars. We interpret this as an emerging cluster, perhaps triggered by the nearby O7���II star. We also find a number of B-type giants. Some of them are located at approximately the same distance, and may be part of an older population in the same area, characterised by much lower reddening. A few have shorter distance moduli and are likely to be located in the Sagittarius arm. Conclusions. The line of sight in this direction is very complex. Optically visible tracers delineate two spiral arms, but seem to be absent beyond d ��� 3 kpc. Several H���ii regions in this area suggest that the Scutum-Crux arm contains thick clouds actively forming stars. All these populations are projected on top of the major stellar complex signposted by the clusters of red supergiants.

Massive open star clusters using the VVV survey III. A young massive cluster at the far edge of the Galactic bar

Context. Young massive clusters are key to map the Milky Way���s structure, and near-infrared large area sky surveys have contributed strongly to the discovery of new obscured massive stellar clusters. Aims. We present the third article in a series of papers focused on young and massive clusters discovered in the VVV survey. This article is dedicated to the physical characterization of VVV���CL086, using part of its OB-stellar population. Methods. We physically characterized the cluster using JHKS near-infrared photometry from ESO public survey VVV images, using the VVV-SkZ pipeline, and near-infrared K-band spectroscopy, following the methodology presented in the first article of the series. Results. Individual distances for two observed stars indicate that the cluster is located at the far edge of the Galactic bar. These stars, which are probable cluster members from the statistically field-star decontaminated CMD, have spectral types between O9 and B0���V. According to our analysis, this young cluster (1.0 Myr < age < 5.0 Myr) is located at a distance of 11+5-6 kpc, and we estimate a lower limit for the cluster total mass of (2.8+1.6-1.4) �� 103 M���. It is likely that the cluster contains even earlier and more massive stars.

VdBH 222: a starburst cluster in the inner Milky Way

Context. It has been suggested that the compact open cluster VdBH 222 is a young massive distant object. Aims. We set out to characterise VdBH 222 using a comprehensive set of multi-wavelength observations. Methods. We obtained multi-band optical (UBVR) and near-infrared (JHKS) photometry of the cluster field, as well as multi-object and long-slit optical spectroscopy for a large sample of stars in the field. We applied classical photometric analysis, as well as more sophisticated methods using the CHORIZOS code, to determine the reddening to the cluster. We then plotted dereddened HR diagrams and determined cluster parameters via isochrone fitting. Results. We have identified a large population of luminous supergiants confirmed as cluster members via radial velocity measurements. We find nine red supergiants (plus one other candidate) and two yellow supergiants. We also identify a large population of OB stars. Ten of them are bright enough to be blue supergiants. The cluster lies behind ���7.5 mag of extinction for the preferred value of RV = 2.9. Isochrone fitting allows for a narrow range of ages between 12 and 16 Ma. The cluster radial velocity is compatible with distances of ~6 and ~10 kpc. The shorter distance is inconsistent with the age range and Galactic structure. The longer distance implies an age ��� 12 Ma and a location not far from the position where some Galactic models place the far end of the Galactic bar. Conclusions. VdBH 222 is a young massive cluster with a likely mass >20 000 M���. Its population of massive evolved stars is comparable to that of large associations, such as Per OB1. Its location in the inner Galaxy, presumably close to the end of the Galactic bar, adds to the increasing evidence for vigorous star formation in the inner regions of the Milky Way.

A new survey of cool supergiants in the Magellanic Clouds

Aims. In this study we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. Methods. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership in the clouds. Results. Around two hundred new red supergiants have been detected, hinting at a yet to be observed large population. Using near- and mid-infrared photometry we study the brightness distribution of these stars, the onset of mass-loss, and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid- and near-infrared photometry to improve the observational efficiency of similar programs to this.

Standard infrared prism spectra.

Vol. 57 has title: Standard infrared grating spectra.

Infrared spectra of polymers and resins.

Cover title: Infrared spectra of plastics and resins.

Time-resolved spectroscopy of the metal-to-metal charge transfer excited state in dinuclear cyano-bridged mixed-valence complexes

Visible pump-probe spectroscopy has been used to identify and characterize short-lived metal-to-metal charge transfer (MMCT) excited states in a group of cyano-bridged mixed-valence complexes of the formula [(LCoNCMII)-N-III(CN)(5)](-), where L is a pentadentate macrocyclic pentaamine (L-14) or triamine-dithiaether (L-14S) and M is Fe or Ru. Nanosecond pump-probe spectroscopy on frozen solutions of [(LCoNCFeII)-Co-14-N-III(CN)(5)](-) and [(LCoNCFeII)-Co-14S-N-III(CN)(5)](-) at 11 K enabled the construction of difference transient absorption spectra that featured a rise in absorbance in the region of 350-400 nm consistent with the generation of the ferricyanide chromophore of the photoexcited complex. The MMCT excited state of the Ru analogue [(LCoNCRuII)-Co-14-N-III(CN)(5)](-) was too short-lived to allow its detection. Femtosecond pump-probe spectroscopy on aqueous solutions of [(LCoNCFeII)-Co-14-N-III(CN)(5)](-) and [(LCoNCFeII)-Co-14S-N-III(CN)(5)](-) at room temperature enabled the lifetimes of their Co-II-Fe-III MMCT excited states to be determined as 0.8 and 1.3 ps, respectively.