This study focuses on the analysis of atmospheric particles sampled from two different field campaigns: the field study at a cattle feeding facility in the summer from 2005 to 2008 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. A ground site field study at a representative large cattle feeding facility in the Texas Panhandle was conducted to characterize the particle size distributions, hygroscopicity, and chemical composition of agricultural aerosols. Here, a first comprehensive dataset is reported for these physical and chemical properties of agricultural aerosols appropriate for use in a site-specific emission inventory. The emission rate and transport of the aerosols are also discussed. In addition, mixing ratios of total and gaseous ammonia were measured at the same field in 2007 and 2008. Measurements such as these provide a means to determine whether the fugitive dust emitted from a typical large feedlot represents a health concern for employees of the feeding operation and the nearby community. Detailed chemical composition of aircraft-sampled particles collected during ISDAC was studied. Filter samples were collected under a variety of conditions in and out of mixed phase and ice clouds in the Arctic. Specifically, particles were sampled from a mixed-phase cloud during a period of observed high concentrations of ice nuclei (IN), a biomass plume, and under relatively clean ambient conditions. Composition of particles was studied on a particle-by-particle basis using several microspectroscopy techniques. Based on the elemental composition analysis, more magnesium was found in Arctic cloud residues relative to ambient air. Likewise, based on the carbon speciation analysis, high IN samples contained coated inorganics, carbonate, and black or brown carbon particles. In the samples collected during a flight through a biomass burning plume, water-soluble organic carbon was the dominant overall composition. Due to their hygroscopic nature, these organics may preferably act as cloud condensation nuclei (CCN) rather than IN. Other ambient samples contained relatively higher fractions of organic and inorganic mixtures and less purely water-soluble organics than found in the biomass particles. The most likely source of inorganics would be sea salt. When present, sea salt may further enhance ice nucleation.

Seit Sommersemester 2006 bietet die SLUB mit den Elektronischen Semesterapparaten ESEM einen neuen Service für Studenten der TU Dresden im Internet an. ...

Nanofibrous separators use in lithium-ion batteries brings many advantages. In contrast to contemporary used commercial separators, nanofibrous ones exhibit higher temperature resistance,ionic conductivity and higher electrolyte uptake. Better ionic conductivity is ensured by porous structure and large specific surface. Fibers creates channels for the ionic species motion. Amorphous texture of nanofibers allows quick lithium ionic species motion within the polymeric matrix of separator. Furthermore, these separators exhibit higher volume of uptaken electrolyte. Further advantage of electrospinned nanofibrous separators are both high porosity and chemical stability.

Heroin addiction is inclined to arouse fear, rejection and discriminatory behavior among the general public. Evidence shows that the public perceives heroin as harmful and addictive. Heroin is ranked as the most stigmatized condition. While there is robust literature on mental illness stigma, there is limited research concerning addiction-related stigma. There are very few standardized stigma measures related to perceptions toward persons addicted to heroin. The overall aim of the dissertation was to validate an attribution measurement model toward persons addicted to heroin and to determine its psychometric properties. The dissertation’s study employed an adapted 7-factor measurement model (Corrigan et al., 2002) to examine stigmatizing perceptions towards persons addicted to heroin. This is the first study to systematically evaluate model fit by implementing Exploratory Structural Equation Modeling (ESEM). A total of 657 Sociology students were analyzed over four stages: questionnaire review by expert panel, pilot-test, validation and replication. The study tested multiple incremental models and successfully determined that the results met multiple goodness-of-fit indices. Through ESEM, Sociology-Social Control students supported the hypothesis that the adapted 7-factor attribution measurement model would fit data. The model included: Personal Responsibility, Pity, Anger, Helping Behavior, Dangerousness, Fear and Social Distance factors. Adequate power and sample size was demonstrated to support acceptance of the null hypothesis. In addition to conducting Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA), ESEM tested the psychometric properties of the attribution measurement model. Implementing maximum likelihood extraction with oblique geomin rotation using Mplus software, the Sociology-Social Control students’ validation and replication datasets showed an excellent model fit to the data. Results confirmed support for the superiority of the ESEM solution. The ESEM attribution measurement model fit better than the CFA model. Compared to the ESEM model, elevated factor correlations found in the CFA model were caused by the exclusion of meaningful cross-loadings. Strong psychometric properties for the ESEM attribution model were evidenced, with good internal consistency and excellent test-retest reliability. The factor structure was replicable across the two groups of Sociology-Social Control students. Adequate ESEM incremental and convergent validity was supported by the simultaneous examination of the Social Distance scale and the Personal Consequences of Criminal Stigma measures with the measurement model. In the replication sample, familiarity demonstrated less stigmatizing perceptions than the SOC313 Course. Our findings highlight marked differences between the Sociology-Social Control students and the general population’s perceptions of heroin addicts. The Sociology-Social Control students are not afraid of persons addicted to heroin, nor do they hold them responsible for their condition. To conclude, the study provides newly validated measures with adequate reliability to allow investigators to assess other students’ level of addiction stigma. It is anticipated that the dissertation’s study will lead to further comparative psychometric testing with healthcare students that are directly involved with the care and treatment of persons addicted to heroin to provide a better understanding of the factorial structure of the attribution measurement model. Longitudinal data is also needed to examine our model and how levels of perceptions change over time.

Ce travail est consacré à l'étude de la sorption d'eau et du gonflement des argiles (bentonite MX80 et argilites du Bassin de Paris). On propose une nouvelle approche par microscopie électronique à balayage environnementale (ESEM) couplée à l'analyse digitale d'image pour estimer le gonflement en fonction du temps et de l'humidité relative. L'ESEM est un outil de nouvelle génération encore peu utilisé dans le domaine des argiles, qui permet d'étudier des matériaux hydratés dans différentes conditions d'humidités relatives. Dans ce travail on montre qu'il est possible d'obtenir des informations qualitatives et quantitatives sur le gonflement des argiles à l'échelle de l'agrégat. L'étude de la cinétique permet ainsi d'identifier trois étapes de gonflement, dont l'étape de gonflement proprement dite, décrite par un modèle cinétique de premier ordre. <br />L'étude de la sorption d'eau de la bentonite brute et échangée avec différents cations (Na+, Li+, K+, Ca++, Mg++) a permis d'aborder l'influence des cations sur le potentiel de gonflement. La cinétique d'adsorption, décrite par un modèle de deuxième ordre dépend directement de l'humidité relative, de la masse de l'échantillon et du cation compensateur. <br />L'étude de la texture en conditions sèches et humides de la bentonite MX80 compactée a permis d'observer l'évolution morphologique du réseau poreux (macroporosité) au cours de l'hydratation/ déshydratation. A partir de différentes approches analytiques on constate une diminution de la taille des macropores et/ou mésopores, et l'ouverture de pores inter- agrégats lorsque la densité apparente augmente. <br />L'étude de l'influence de la condensation/ évaporation instantanée d'eau sur les argilites montre que la sensibilité à l'eau augmente lorsque la proportion argileuse augmente; elle est marquée entre autres par une fissuration qui peut être partiellement réversible ou irréversible après quelques cycles de condensation/ évaporation.

The Maya of Central America developed a complex society: among their many achievements they developed a writing system, complex calendar and were prolific builders. The buildings of their large urban centres, such as Copan in Honduras, were decorated with painted stucco, moulded masks, carving and elaborate murals, using a range of coloured pigments. In this study the paints used on the buildings of Copan and some ceramic sherds have been investigated, non-destructively, using micro-Raman spectroscopy, micro-ATR infrared spectroscopy, environmental scanning electron microscopy with energy dispersive X-ray analysis (ESEM-EDX) and FTIR-ATR imaging spectroscopy. The paint samples come from four buildings and one tomb covering three time periods in the four hundred year history of Copan. The main pigment used in the red paint on these samples was identified as haematite, and the stucco as a mixture of calcite particles dispersed throughout a calcite-based lime wash stucco. The composition and physical nature of the stucco changed through time, indicating a refining of production techniques over this period. A range of minor mineral components have been identified in each of the samples including rutile, quartz, clay and carbon. The presence and proportion of these and other minerals differed in each sample, leading to unique mineral signatures for the paint from each time period. Green and grey paints have also been identified on one of the buildings, the Rosalila Temple. The green pigment was identified as a celadonite-based green earth, and the grey pigment as a mixture of carbon and muscovite. The combination of carbon and mica to create a reflective paint is a novel finding in Maya archaeology. The high spatial resolution of the micro-FTIR-ATR spectral imaging system has been used to resolve individual particles in tomb wall paint and to identify their mineralogy from their spectra. This system has been used in combination with micro-Raman spectroscopy and ESEM-EDX mapping to characterize the paint, which was found to be a mixture of haematite and silicate particles, with minor amounts of calcite, carbon and magnetite particles, in a sub-micron haematite and calcite matrix. The blending of a high percentage of silicate particles into the haematite pigment is unique the tomb sample. The stucco in this tomb wall paint has finely ground carbon dispersed throughout the top layer providing a dark base for the paint layer. Changing paint mixtures and stucco composition were found to correlate with changes in paint processing techniques and building construction methods over the four hundred years of site occupation.

Dans ce travail, la nanoindentation et la Microscopie à Force Atomique ont été utilisées pour déterminer les caractéristiques mécaniques et morphologiques de l'os cortical aux échelles micro et nanoscopique. Les propriétés mécaniques qui dépendent du temps, élastique et plastique ont été quantifiées par nanoindentation en utilisant une méthode spécifique. Les essais ont été réalisés sur trois différentes espèces d'os cortical. Dans un premier temps, l'os du rat fut utilisé pour quantifier l"évolution des propriétés mécaniques de la croissance à la sénescence. La variation des propriétés mécaniques avec l'âge fut démontrée et sa corrélation avec les propriétés physico-chimiques établie. Les équations de prédiction ont été proposées afin de décrire le comportement mécanique puis pour quantifier un âge de maturation apparent pour chaque propriété. Dans un deuxième temps, le comportement mécanique qui dépend du temps a été examiné sur l'os humain. Les systèmes Haversiens avec différents contenus du minéral furent identifiés à partir d'images ESEM. Les résultats démontrent l'hétérogénéité mécanique des systèmes Haversiens et l'influence des propriétés mécaniques qui dépendent du temps sur l'anisotropie de l'os. Enfin, l'os bovin fut utilisé pour quantifier les effets mécaniques et morphologiques du processus de déminéralisation. Le résidu organique de l'os déminéralisé présente un comportement mécanique quasi-isotrope. Les images AFM montrent que les fibres de collagène sont orientées dans une direction privilégiée. Les données obtenues pourront servir à développer des matériaux biomimétiques et à établir des lois de comportement multi-échelles de l'os cortical. / Bone is a dynamical, anisotropic, hierarchical, inhomogeneous and time-dependent biological material. At the micro and nano scales, their mechanical and structural characterizations are still being a challenging topic. Nanoindentation and Atomic Force Microscopy are used to assess the mechanical and morphological characteristics of cortical bones. Time-dependent, elastic and plastic mechanical properties were computed using the nanoindentation method proposed by (Mazeran et al., 2012). Experiments were performed on different species of bones for different conditions. Wistar rat femoral cortical bone was used to assess the evolution of the mechanical properties in a life span model (from growth to senescence). The variation of the mechanical properties with age was evidenced and their correlation with physico-chemical properties was established. Then, prediction equations were proposed to describe these behaviours. From these equations, it is possible to estimate an apparent maturation age for each mechanical property. Our findings suggest maturation age is earlier and growth rate are higher for elastic properties than for time-dependent mechanical properties. Time-dependent mechanical behaviour of Human femoral cortical bones were assessed considering its heterogeneity. Haversian systems with different apparent mineral content were identified by means of their apparent grey levels obtained from ESEM images. Results prove the mechanical heterogeneity of the Haversian systems and highlight the influence of the time-dependent mechanical properties in the anisotropic behaviour of bone. Bovine femoral cortical bone was used to quantify the mechanical and morphological effects of the demineralization process. Bone seems to have a quasi-isotropic mechanical behaviour after mineral loss. AFM images of the remaining organic components show that collagen fibrils are oriented in a possible privileged direction. According to our knowledge, few investigations have been performed simultaneously on mechanical, morphological and physico-chemical properties of bone. All these results provide a better understanding of the interactions of the collagen-mineral matrix, bone remodelling and their influence especially in the time-dependent mechanical response. Data reported in this work could be useful to develop and to improve multi-scale bone models and multi-scale constitutive laws for cortical bone.

Flow accelerated corrosion (FAC) is a major concern in the power industry as it causes thinning of the pipes by the dissolution of the passive oxide layer formed on the pipe surface. Present research deals with comparing the protection offered by the magnetite (Fe3O4) versus maghemite (γ-Fe2O3) phases thickness loss measurements. Fourier transform infrared spectroscopy (FTIR) is used in distinguishing these two elusive phases of iron oxides. Representative pipes are collected from high pressure steam extraction line of the secondary cycle of unit 2 of Comanche Peak Steam Electric Station (CPSES). Environmental scanning electron microscopy (ESEM) is used for morphological analysis. FTIR and X-ray diffraction (XRD) are used for phase analysis. Morphological analysis showed the presence of porous oxide surfaces with octahedral crystals, scallops and "chimney" like vents. FTIR revealed the predominance of maghemite at the most of the pipe sections. Results of thickness measurements indicate severe thickness loss at the bend areas (extrados) of the pipes.

This graduation theses in introduction deals with principle and problems of electron signal detection in scanning electron microscopy and charging of insulating specimens in SEM. The experimental part of the thesis describe the methods of qualification and quantification of insulating specimen charging effect observed in environmental scanning electron microscope through the use of ionisation and scintillation detector in dependence on water vapour pressure in specimen chamber. The goal of the thesis is formation of the methodics useful to evaluate charging effect at insulating specimens observing and on the basis of measuring, determine optimal conditions for insulating specimen observation with ionisation and scintillation detector.

This diploma thesis deals with electron microscopy. Examined equipment is environmental scanning electron microscope (ESEM), namely scintillation a detector of the microscope. There is solved the influence of the profile of holes in diaphragms to the resulting pressure and gas flow on the path of secondary electrons at the detector. Introductory part of thesis informs about microscopy in general, with concentration on electron microscopy; especially on scanning microscope, because research is taken just on the environmental scanning electron microscope. Another part informs about both general principles of dynamics of gases and with finite volume method. Another part deals with concrete used software and with setting of individual parameters for calculation. At the beginning of calculation are used five basic profiles of holes in diaphragms for pressure 1000 Pa in the chamber of the sample. For modelling individual shapes is used 3D parametric modeller SolidWorks. Analysis of circulation of secondary electrons through detector is made by using Cosmos FloWorks module. The most suitable type of diaphragms is chosen from measured models. Another part of diploma thesis deals with measuring of chosen types of diaphragms for more pressures in the chamber of the sample; the pressure is 200, 400, 600, 800 and 1000 Pa. The outcomes of this research are both models of pressure and speed of circulation inside the detector and graphically processed values by using different diaphragms, respectively one type of a diaphragm in different pressures. Production drawings of each diaphragm, together with calculated models, are enclosed.