The present study deals with the physical characterization of macrodefect free cements produced by ICI. These materials are made through a specialized mixing technique which incorporates an organic polymer into the cement/water system. The high mechanical strength and low porosity of this class of hardened cement paste had been well documented, however, a detailed characterization of the physical nature of the microstructure had not previously been attempted. Two classes of macrodefect free material were studied, based on Ordinary Portland cement and High Alumina cement, respectively. The porosities of these two materials were determined in their original state and after various forms of heat treatment and conditioning. Samples based on Ordinary Portland cement had a well defined narrow pore size distribution, even after heat treatment, while the High Alumina cement samples displayed a very low total pore volume in their original state, but subsequent heat treatment led to the developement of porosity over a wide range of pore sizes. These fundamental differences in the pore size distributions had significant effects on the homogeneity and reproducibility of the microstructures of the samples. The porosity generated by heat treatment was found to be unstable in the presence of water. In general, reductions in the porosities and permeabilities were observed. This was due to the formation of fresh cement hydrate gel within the pore structure, which caused a shift in the pore size distributions towards smaller pores.

The most speciose group of fishes in the Gulf of Mexico is the dragonfishes (Family: Stomiidae). These fishes are dominant mesopelagic predators occurring throughout the world’s oceans, including the Antarctic seas. Little is known regarding their reproductive ecology, a consequence attributed to insufficient sample sizes of mature adults due to inadequacies of sampling gear; larger, sexually mature stomiid adults are more adept at net avoidance, thereby obfuscating synoptic reproductive biology studies. Between 2010-2011, the Offshore Nekton Sampling and Analysis Program was initiated in the northern Gulf of Mexico over all four seasons using a discrete-depth sampling system (MOCNESS) and a large, commercial-sized midwater trawl (Irish herring trawl). Gonads were dissected from 714 individuals belonging to 47 species of stomiids, of which the most 12 abundant species were subjected to detailed analysis. Female ovaries possessed an asynchronous oocyte development, suggesting that females are iteroparous. Males exhibited a similar pattern. Chauliodus sloani had an overall sex ratio that favored females, and was the only species in which the overall sex ratio significantly differed from the expected 1:1 ratio (male:female) (P < 0.05). Considering just mature specimens, Aristostomias xenostoma, Malacosteus niger, Eustomias fissibarbis, and Eustomias schmidti had sex ratios that favored males, and were the only species in which the sex ratio significantly differed from even (P < 0.05). Eustomias hypopsilus was the only species in which mean biomass significantly differed between sexes. Histological analysis and binomial regression indicated that females of the 12 most abundant species matured at larger lengths than males. Generally, only females were present in the larger size classes, suggesting that females also become larger than males. Size distribution plots by gear type to assess gear selectivity revealed two patterns: the MOCNESS caught fewer specimens per species than the Irish herring trawl, and the MOCNESS caught predominantly smaller specimens. These data are essential for ecosystem-based modeling of global deep-pelagic ecosystems, which contain the overwhelming majority of Earth’s fish biomass.

This thesis is about firm dynamics, and relates to the size and growth-rate distribution of firms. As such, it consists of an introductory and four separate chapters. The first chapter concerns the size distribution of firms, the two subsequent chapters deal more specically with high-growth firms (HGFs), and the last chapter covers a related topic in distributional estimation theory. The first three chapters are empirically oriented, whereas the fourth chapter develops a statistical concept. / <p>QC 20130215</p>

Magíster en Ciencias, Mención Geología / Geólogo / El presente trabajo presenta un nuevo método para desarrollar Crystal Size Distributions (CSD), un tipo de análisis textural cuantitativo que compara la densidad de población de cristales respecto a su tamaño. Basado en la modelación de la curva de distribución acumulada del tamaño de cristales a través de una función error, se obtienen CSD los que permiten calcular tasas de crecimiento y nucleación de distribución gaussiana asimétrica con respecto al tiempo. Este procedimiento fue aplicado en una muestra de la erupción de 1971 del volcán Villarrica entregando el tamaño límite que distingue microlitos de fenocristales y mostrando un fuerte incremento de las tasas de crecimientos y nucleación de cristales en 2 y 8 órdenes de magnitud, respectivamente, producto del ascenso de magma y cristalización en superficie. Este procedimiento también fue aplicado en cuarzo-monzodioritas del Plutón La Gloria, entregando una distribución sigmoidal de la fracción volumétrica de cristales con respecto al tiempo la que puede ser dividida en 3 etapas diferentes: una primera que muestra un muy bajo incrementos de la fracción volumétrica, la cual coincide con el pico de la tasa de crecimiento, una segunda que muestra un alto incremento de la fracción volumétrica, la cual coincide con el pico de la tasa de nucleación y una tercera que muestra una segunda disminución debido al bajo volumen disponible para nuclear nuevos cristales y recrecer antiguos. A pesar de los aportes que genera este nuevo método, el CSD seguiría siendo insuficiente para identificar distintos procesos magmáticos tales como ascenso de magma respecto a cristalización en superficie o mezcla de magmas, calentamientos o sistemas multireservorios. Es por esto que se acoplan los parámetros cinéticos de cristalización calculados a partir de CSD con la composición de plagioclasas ya que ambos dependen tanto de la temperatura como de la presión de agua. El modelo de acoplamiento es aplicado a la erupción de 1915 del Volcán Lassen Peak. Se registran dos procesos de calentamiento previo a la erupción, el segundo producto de mezcla de magmas dacíticos y andesíticos. Se registran condiciones estables del reservorio dacítico a presión de agua de 200 MPa, 830 ºC generando plagioclasas de contenido de anortita alrededor de 0.37 con lo que se infiere una cota mínima de profundidad del reservorio de 7 km. Posterior al calentamiento se registra una etapa de devolatilización a una temperatura estable de 940 ºC y el ascenso de magma el cual ocurriría en 18 horas.

Dissolved organic matter (DOM) is one of the largest carbon reservoirs on this planet and is present in aquatic environments as a highly complex mixture of organic compounds. The Florida coastal Everglades (FCE) is one of the largest wetlands in the world. DOM in this system is an important biogeochemical component as most of the nitrogen (N) and phosphorous (P) are in organic forms. Achieving a better understanding of DOM dynamics in large coastal wetlands is critical, and a particularly important issue in the context of Everglades restoration. In this work, the environmental dynamics of surface water DOM on spatial and temporal scales was investigated. In addition, photo- and bio-reactivity of this DOM was determined, surface-to-groundwater exchange of DOM was investigated, and the size distribution of freshwater DOM in Everglades was assessed. The data show that DOM dynamics in this ecosystem are controlled by both hydrological and ecological drivers and are clearly different on spatial scales and variable seasonally. The DOM reactivity data, modeled with a multi-pool first order degradation kinetics model, found that fluorescent DOM in FCE is generally photo-reactive and bio-refractory. Yet the sequential degradation proved a “priming effect” of sunlight on the bacterial uptake and reworking of this subtropical wetland DOM. Interestingly, specific PARAFAC components were found to have different photo- and bio-degradation rates, suggesting a highly heterogeneous nature of fluorophores associated with the DOM. Surface-to-groundwater exchange of DOM was observed in different regions of the system, and compositional differences were associated with source and photo-reactivity. Lastly, the high degree of heterogeneity of DOM associated fluorophores suggested based on the degradation studies was confirmed through the EEM-PARAFAC analysis of DOM along a molecular size continuum, suggesting that the fluorescence characteristics of DOM are highly controlled by different size fractions and as such can exhibit significant differences in reactivity.

The aim of this thesis is to compare the results of water infiltration from field tests, from laboratories and from numerical modeling at two selected locations. The first objective is the search procedure and the description of both sites and its adjacent areas. Further work continues with infiltration field tests using ring infiltrometer, at first theoretically for each method, and then practically with own personal measurements in the field. Further from the collected soil samples the measurements are performed in the laboratory, first in the permeameter, and followed by the grain size distribution test, from which the hydraulic conductivity is derived by using empirical formulas. At last the numerical modeling is used and all the results are compared. In the final phase of thesis the recommendations are given for infiltration at various locations and comparsion of the infiltration methods.

An adsorbent suitable for adsorption desalination cycles is essentially characterized by a hydrophilic and porous structure with high surface area where water molecules are adsorbed via hydrogen bonding mechanism. Silica gel type A++ possesses the highest surface area and exhibits the highest equilibrium uptake from all the silica gels available in the market, therefore being suitable for water desalination cycles; where adsorbent’s adsorption characteristics and water vapor uptake capacity are key parameters in the compactness of the system; translated as feasibility of water desalination through adsorption technologies. The adsorption characteristics of water vapor onto silica gel type A++ over a temperature range of 30 oC to 60 oC are investigated in this research. This is done using water vapor adsorption analyzer utilizing a constant volume and variable pressure method, namely the Hydrosorb-1000 instrument by Quantachrome. The experimental uptake data is studied using numerous isotherm models, i. e. the Langmuir, Tóth, generalized Dubinin-Astakhov (D-A), Dubinin-Astakhov based on pore size distribution (PSD) and Dubinin-Serpinski (D-Se) isotherm for the whole pressure range, and for a pressure range below 10 kPa, proper for desalination cycles; isotherms type V of the International Union of Pure and Applied Chemistry (IUPAC) classification were exhibited. It is observed that the D-A based on PSD and the D-Se isotherm models describe the best fitting of the experimental uptake data for desalination cycles within a regression error of 2% and 6% respectively. All isotherm models, except the D-A based on PSD, have failed to describe the obtained experimental uptake data; an empirical isotherm model is proposed by observing the behavior of Tóth and D-A isotherm models. The new empirical model describes the water adsorption onto silica gel type A++ within a regression error of 3%. This will aid to describe the advantages of silica gel type A++ for the design of adsorption desalination processes where reducing capital cost and footprint area are highly important parameters to take into account.

Atmospheric aerosol particles play an important role in global climate change, via direct and indirect radiative forcing. Elemental carbon (EC) and nitrate are important contributors to anthropogenic aerosol radiative forcing over Europe, since they strongly absorb and/or scatter solar radiation, respectively. However, the evaluation of their climate effects remains highly uncertain. Improvements on the simulation of particle number/mass size distribution (PSD) in modelling will help us to refine model assessments of climate change. The simulations were performed over Europe with a fully online-coupled regional air quality model (WRF-Chem) for the time period of September 10-20th, 2013. Measurements in the HOPE-Melpitz campaign and other datasets in Europe were adopted to evaluate the model uncertainties. The meteorological conditions were well reproduced by the simulations. However, a remarkable overestimation of coarse mode PSD was found in the simulations. The overestimation was mainly contributed by EC, sodium nitrate and sea salt (SSA), stemming from the inadequate emission of EC and SSA. The EC inventory overestimates EC point sources in Germany and the fractions of coarse mode EC emissions in Eastern Europe and Russia. Allocating too much EC emission into the coarse mode could shorten EC lifetime and reduce its long-range transport, thus partly (~20-40%) explaining the underestimation of EC in Germany, when air masses came from eastern direction in previous studies. Furthermore, WRF-Chem overestimated coarse mode SSA mass concentrations by factors of about 8-20 over northwestern and central Europe in this study, due to the shortcoming of its emission scheme. This could facilitate the coarse mode sodium nitrate formation and lead to ~140% overestimation of coarse mode nitrate. Under such circumstances, nitric acid was exhausted, and fine mode ammonium nitrate formation was inhibited. The overestimated SSA shaped the PSD of nitrate towards larger sizes, which might influence the optical properties, lifetime and climate effect of nitrate accordingly. A transport mechanism would broaden the influence of SSA on nitrate PSD to central Europe, where a considerable amount of nitrate precursors and ammonium nitrate is present.:Table of Contents List of Figures List of Tables Abbreviations 1. Introduction 1.1 Particle size distribution 1.2 Elemental carbon particle size distribution simulation 1.3 Chemical pathways for particulate nitrate 1.4 Influence of sea salt on nitrate particle mass size distribution 1.5 Objectives 2. Methodology 2.1. WRF-Chem model 2.1.1. General description 2.1.2. Model configuration 2.1.3 Anthropogenic source emissions 2.1.4 Natural source emissions 2.2 HOPE-Melpitz campaign 2.3 GUAN network over Germany 2.4 Other datasets 3. Results and Discussion 3.1 First publication 3.1.1 Evaluation of the size segregation of elemental carbon (EC) emission in Europe: influence on the simulation of EC long-range transportation 3.1.2 Supporting information 3.2 Second publication 3.2.1 Sea salt emission, transport and influence on size-segregated nitrate simulation: a case study in northwestern Europe by WRF-Chem 3.2.2 Supporting information 4. Summary and Conclusions 5. Outlook Appendix A Bibliography Acknowledgements

Due to its prevalence over large, densely populated areas, ammonium nitrate is an important chemical species in aerosol research. However, due to its volatility at ambient temperatures and over low temperature gradients, ammonium nitrate can be a difficult species to accurately measure. The volatility of ammonium nitrate is known to be dependent on temperature, relative humidity, the internal mixing state of the particle, and availability of the precursor gas constituents. The particle's physical state affects the equilibrium constant value of the ammonium nitrate - nitric acid / ammonia exchange and helps determine the dissociation rate. For indoor aerosol research, the outdoor originating aerosol particles' exposure to the new physical conditions indoors, such as changes in temperature, humidity, and particle-surface reactions within the microenvironment all accelerate ammonium nitrate dissociation. This increased rate of partitioning can generate artifacts on datasets, increase indoor particle formation, and accelerate the corrosion of cultural antiquities through acidification. The magnitude of these impacts is uncertain due to the current lack of knowledge on particle transformation processes when outdoor originating particles migrate indoors. To address this gap in knowledge, this thesis...

The separation of solids from biological wastewater treatment is an important step in the treatment process, as it has a significant impact on effluent water quality. The moving bed biofilm reactor (MBBR) technology is a proven upgrade or replacement wastewater treatment system for carbon and nitrogen removal. However, a challenge of this technology is the characteristics of the effluent solids that results in their poor settlement; with settling being the common method of solids removal. The main objective of this research is to understand and expand the current knowledge on the settling characteristics of MBBR produced solids and the parameters that influence them. In particular, in this dissertation, the impacts are studied of carrier types, biofilm thickness restraint design of carriers, and varying carbonaceous loading rates on MBBR performance, biofilm morphology, biofilm thickness, biofilm mass, biofilm density, biofilm detachment rate, solids production, particle size distribution (PSD) and particle settling velocity distribution (PSVD). With this aim, three MBBR reactors housing three different carrier types were operated with varying loading rates. In order to investigate the effect of carrier geometrical properties on the MBBR system, the conventional, cylindrically-shaped, flat AnoxK™ K5 carrier with protected voids was compared to two newly-designed, saddle-shaped Z-carriers with the fully exposed surface area. Moreover, the AnoxK™ Z-200 carrier was compared to the AnoxK™ Z-400 carrier to evaluate the biofilm thickness restraint design of these carriers, where the Z-200 carrier is designed for greater biofilm thickness-restraint. The Z-200 carrier is designed to limit the biofilm thickness to the level of 200 µm as opposed to 400 µm for the Z-400 carrier. Finally, to investigate the effects of varying carbonaceous loading rates on system removal performance, biofilm characteristics and solids characteristics, further analyses were performed at three different loading rates of 1.5 to 2.5 and 6.0 g-sBOD/m2·d in steady-state conditions. The PSD and the PSVD analyses were combined to relate these two properties. A settling velocity distribution analytical method, the ViCAs, was applied in combination with microscopy imaging and micro-flow imaging to investigate the relation of PSD and settling behaviour of MBBR produced particles. The obtained results have indicated that the carrier type significantly impacted the MBBR performance, biofilm, and particle characteristics. As such, the K5 carrier MBBR system demonstrated a statistically significantly higher carbonaceous removal rate and efficiency (3.8 ± 0.3 g-sBOD/m2·d and 59.9 ± 3.0% sBOD removal), higher biofilm thickness (281.1 ± 8.7 μm), higher biofilm mass per carrier (43.9 ± 1.0 mg), lower biofilm density (65.0 ± 1.5 kg/m3), lower biofilm detachment rate (1.7 ± 0.7 g-TSS/ m2·d) and hence lower solids production (0.7 ± 0.3 g-TSS/d) compared to the two Z-carriers. The Z-carriers' different shape exposes the biofilm to additional shear stress, which could explain why the Z-carriers have thinner and denser biofilm, resulting in higher solids production and lower system performance in comparison with K5. Moreover, the carrier type was also observed to impact the particle characteristics significantly. PSD analysis demonstrated a higher percentage of small particles in the Z-carrier system effluent and hence a significantly lower solids settling efficiency. Therefore, the solids produced in the K5 reactor have shown enhanced settling behaviour, consisting of larger particles with faster settling velocities compared to Z-carriers. This dissertation also investigated the effects of restraint biofilm thickness on MBBR performance by comparing the Z-200 biofilm thickness-restraint carrier to the Z-400 carrier. No significant difference was observed in removal efficiency, biofilm morphology, biofilm density, biofilm detachment rate, and solids production between the Z-200 to the Z-400 carriers. The PSD and the PSVD analyses did not illustrate any significant difference in the particles’ settling behaviour for these two biofilm thickness restraint carriers, indicating that the biofilm thickness-restraint carrier design was not a controlling factor in the settling potential of MBBR produced solids. Finally, this research studied the effect of varying loading rates and demonstrated a positive, strong linear correlation between the measured sBOD loading rate and the removal rate, indicating first-order BOD removal kinetics. The biofilm thickness, biofilm density and biofilm mass decreased when the surface area loading rate (SALR) was increased from 2.5 to 6.0 g-sBOD/m2·d. The solids retention time (SRT) was also shown to decrease by increasing the SALR, where the lowest SRT (1.7 ± 0.1 days) was observed at the highest SALR, with the highest cell viability (81.8 ± 1.7%). Significantly higher biofilm detachment rate and yield were observed at SALR 2.5, with the thickest biofilm and a higher percentage of dead cells. Consequently, a higher fraction of larger and rapidly settling particles was observed at SALR of 2.5 g-sBOD/m2·d, which leads to a significantly better settling behaviour of the MBBR effluent solids. This study expands the current knowledge of MBBR-produced particle characteristics and settling behaviour. A comprehensive understanding of the MBBR system performance and the potential influencing factors on the MBBR produced solids, particle characteristics, and their settleability will lead to optimized MBBR design for future pilot- and full-scale applications of the MBBR.