The analysis of organic pollutants in water is traditionally done following EPA procedures which commonly use liquid-liquid extraction. One liter of water is extracted three times with 60 mL of an organic solvent. The extract is concentrated and analyzed by gas chromatography. This procedure is time consuming and can cause losses of semi-volatile components, in addition to requiring a relatively large amount of organic solvent (180 mL). By performing the extraction directly in a GC autosampler vial using one milliliter of contaminated water and one milliliter of organic solvent, then injecting a large volume (~150 mL) of the organic layer taken directly from the vial by an autosampler, the same analysis can be done simpler, quicker, and with much less organic solvent (1 mL). / Master of Science

Remotely located and sparsely populated areas often do not have access to an efficient grid connection for electricity supply. However, plenty of biomass is normally available in such areas. Instead of employing island solutions such as small diesel generators or large battery stacks for power provision, a flexibly operating microscale biomass power plant using locally available and renewable feedstock is not only an efficient way of providing those areas with competitive and reliable electricity, but also a step towards energy self sufficiency for a large share of areas worldwide, and towards mitigating the looming high costs of grid infrastructure upgrading and extension. A novel power plant design combining thermo chemical and biochemical biomass treatment was developed in this research. This system consists of a small scale gasifier and an anaerobic digester unit, both coupled to a gas storage system and a micro turbine as the generation unit. This design is suitable to continuously provide reliable electricity and accommodate fluctuating residential power demand, and it can be scaled to a level of around 100kWe, which is a fitting size for a group of residential customers, such as in a remote village. The project covers a review of available technology; the choice of suitable technology for such a plant and the design of the system; the set up of a detailed plant model in chemical engineering software; extensive simulation studies on the basis of load profiles to evaluate and optimise operation; and feedstock sourcing, efficiency and economic analyses. It will be shown that such a system is a feasible and economic solution for remote power supply, and that it can overcome many of the current obstacles of electrifying rural regions.

As superligas à base de cobalto são bem conhecidas por sua excelente resistência ao desgaste. Muitas pesquisas reportadas na literatura abordam o comportamento do desgaste destas ligas, seja no desgaste por deslizamento, erosivo ou abrasivo. Não obstante, o desgaste microabrasivo destas ligas não tem sido muito investigado, apesar dos danos causados por este tipo de solicitação. O comportamento do desgaste microabrasivo de três superligas à base de cobalto: a) 48% Co, 29 %Cr, 19 % Fe; b) uma liga com composição química próxima à da liga comercial Tribaloy T400 (Co 56 %, Cr 8.5%, Mo 29% Si 3.3 %) e c) uma liga com composição próxima à da liga comercial Stellite 6 (Co 64%, Cr 24 %, W 4.2 %, C 2,3%) foram investigadas. Os ensaios de microabrasão foram conduzidos com três abrasivos SiO2, Al2O3, e SiC em suspensão em água destilada, com concentração de 0,1 g/cm3. A carga aplicada foi de 0,3 N, a velocidade angular 20 rpm e a distância total de deslizamento, 48 metros. A análise das superfícies desgastadas por microscopia óptica, eletrônica de varredura e por perfilometria de contato mostraram que o tamanho, forma e dureza dos abrasivos podem influenciar significativamente os coeficientes de desgaste. Os ensaios conduzidos com partículas abrasivas de SiC e Al2O3 apresentaram maiores coeficientes de desgaste que os conduzidos com partículas de SiO2. A Liga Co-Cr-Fe mostrou os maiores coeficientes de desgaste quando comparada com as demais ligas, devido à baixa fração volumétrica de partículas de segunda fase, duras, precipitadas em sua microestrutura. Durante os ensaios, as três ligas, ensaiadas com os três diferentes abrasivos, apresentaram coeficientes de desgaste crescentes com o aumento da dureza do abrasivo; observou-se uma variação linear dos coeficientes de desgaste com a razão entre a dureza do abrasivo (Ha) e a dureza composta da liga (Hs), com R2 = 0.74. O micromecanismo dominante em todos os ensaios foi o desgaste abrasivo a dois corpos (grooving wear). A liga com composição próxima à da liga comercial Tribaloy T400, contendo fases de Laves dispersas em sua microestrutura, apresentou uma transição de micromecanismo de desgaste dúctil para frágil, quando submetida a ensaios com partículas abrasivas de Al2O3. Assim sendo, o volume de material removido nesta liga foi ligeiramente maior que o observado no ensaio com partículas de SiC. Na liga contendo baixa fração volumétrica de partículas de segunda fase, com matriz constituída por Co (CFC), observou-se uma camada subsuperficial nanocristalina de aproximadamente 1 µm de espessura, severamente deformada, imediatamente abaixo da superfície desgastada. Concluiu-se que o desgaste microabrasivo induziu a recristalização a frio do material encruado, com formação de grãos equiaxiais de dimensões nanométricas. / Cobalt alloys are well known for their excellent wear resistance. Many investigations are reported in literature related to the behavior of erosive, abrasive or sliding wear of these alloys. Nevertheless, the micro-abrasive wear of these alloys has not been thoroughly investigated, despite the damage caused by this type of wear. The microabrasive wear behavior of three cobalt alloys: a) 48 wt.% Co, 29 wt.% Cr, 19 wt.% Fe; b) an alloy with chemical composition close to Tribaloy T400 (56 wt.% Co, 8.5 wt.% Cr, 29% wt. Mo, 3.3 wt. %Si) and c) an alloy with chemical composition close to Stellite 6 (64wt.% Co 24 wt.% Cr, 4.2 wt.% W, 2,3 wt.% C were investigated. The tests were carried out using three 0,1 g/cm3 slurries composed by SiO2, Al2O3, and SiC particles, in suspension in distilled water. The applied load was 0.3 N, the rotational speed 20 rpm and the total sliding distance 48 m. Analysis of the worn surfaces of the tested alloys by Optical Microscopy, Scanning Electron Microscopy and Contact Stylus Profilometry showed that abrasive size, shape and hardness could significantly influence the wear coefficients. The tests carried out with SiC and Al2O3 slurries resulted in greater wear rates than those carried out in SiO2 slurry. Stellite 250, showed the greatest wear coefficient, compared to the two other experimental alloys, due to a very low volume fraction of hard second phase particles in the microstructure. Wear coefficients decreased with increasing abrasive particles hardness. An approximate linear correlation with the ratio between the hardness of the abrasives (Ha) and the compound hardness of the alloys (Ha) with a correlation factor R2= 0.74. The dominant wear micromechanism observed in all tests was two-body abrasion (grooving wear). The modified T400 alloy, containing Laves phase showed a transition from ductile to brittle wear mechanisms when testing with alumina slurries. The worn volume was slightly greater than the one observed with SiC. A severely deformed nanocrystalline layer was identified, immediately below the worn surface. It was concluded that cold recrystallization of the work-hardened material occurred, with the formation of nano sized equiaxed grains.

This thesis presents some experimental work in the area of manipulation of microparticles. Manipulation of both magnetic and non magnetic beads as well as microorganisms are addressed. The work on magnetic bead manipulation is focused on controlled transport and release, on a micrometer level, of proteins bound to the bead surface. Experimental results for protein transport and release using a method based on magnetization/demagnetization of micron-sized magnetic elements patterned on a modified chip-surface are presented. Special attention has been placed on minimizing bead-surface interactions since sticking problems have shown to be of major importance when protein-coated beads are used. The work with non-magnetic microparticles is focused on the dielectrophoretic manipulation of microorganisms. Preliminary experimental results for trapping and spatial separation of bacteria, yeast and non-magnetic beads are presented. The overall goal was to investigate the use of dielectrophoresis for the separation of sub-populations of bacteria differing in, for example, protein content. This was, however, not possible to demonstrate using our methods.Within the non-magnetic microparticle work, a method for determining the conductivity of bacteria in bulk was also developed. The method is based on the continuous lowering of medium conductivity of a bacterialsuspension while monitoring the medium and suspension conductivities.

The development of a synthetic method of radiolabelled methylphosphono-fluoridates on a milligram scale is presented. The aim of this method is, besides affording high yield, to choose reaction pathways and reagents so that handling and transfer of labelled toxic substances is minimised, thereby reducing the risk of exposure as much as possible. The only substituent that is stable enough to be labelled is the methyl group, directly bonded to phosphorus. A drawback when labelling the methyl group is that it requires the label to be introduced early in the synthesis since the carbon-phosphorus bond of the methyl substituent usually has to be synthesized a few steps ahead of the final product. Two new classes of reagents for halogenation of phosphorus oxyacids have been developed. Firstly, four different analogues of α-chloroenamines and α-fluoroenamines were evaluated. Secondly, cyanuric fluoride was assessed in solution, but more importantly, as a resin-bound reagent. The reagents are evaluated for halogenation of phosphinic, phosphonic and phosphoric acids. Cyanuric fluoride is also successfully loaded on a polystyrene resin and used as a solid-phase reagent. The reagents produce high yields and low levels of impurities on a milligram scale. Furthermore, a new method for the preparation of mono-alkylated phosphonic acids on a small scale has been developed. The new method utilises the crystal water bound to certain salts to liberate limited amounts of water in a controlled manner. Phosphonic dichlorides are in this way reacted with water to form anhydrides. The anhydride is then cleaved with an appropriate alcohol to produce mono-alkylated phosphonic acids. / Rikard Norlin = Rikard Wärme

The mechanical properties of biomaterials play important roles in performing their specialized functions: synthesizing, storing, and transporting biomolecules; maintaining internal structures; and responding to external environments. Besides biological cells, there are also many other biomaterials that are highly deformable and have a diameter between 1μm and 100μm, comparable to that of most biological cells. For example, many polymeric microcapsules for drug delivery use are spherical particles of micrometers size. In order to mechanically characterize individual micrometer-sized biomaterials, the capability of capturing high-resolution and low-magnitude force feedback is required. This research focuses on the development of micro devices and experimental techniques for quantifying the mechanical properties of alginate-chitosan microcapsules. The micro devices include microelectromechanical systems (MEMS) capacitive force sensors and force-feedback microgrippers, capable of measuring sub-μN forces. Employing the MEMS devices, systems were constructed to perform the micro-scale compression testing of microcapsules. The force sensors are capable of resolving forces up to 110μN with a resolution of 33.2nN along two independent axes. The force sensors were applied to characterizing the mechanical properties of hydrogel microparticles without assembling additional end-effectors. The microcapsules were immobilized by a PDMS holding device and compressed between the sensor probe and holding device. Young's modulus values of individual microcapsules with 1%, 2%, and 3% chitosan coating were determined through the micro-scale compression testing in both distilled deionized (DDI) water and pH 7.4 phosphate buffered saline (PBS). The Young's modulus values were also correlated to protein release rates. Instead of compressing the microcapsule against the wall of the holding device, a force-feedback MEMS microgripper with the capability of directly compressing the microcapsule between two gripping arms has been used for characterizing both the elastic and viscoelastic properties of the microcapsules during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified the Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.

The mechanical response of geomaterials is highly influenced by geometrical and material heterogeneity. To date, most modelling practices consider heterogeneity qualitatively and the choice of input parameters can be subjective. In this study, a novel approach to combine detailed micro-scale characterization with modelling of heterogeneous geomaterials is presented. The influence of micro-scale heterogeneity and microcracks on the mechanical response and brittle fracture of a crystalline rock was studied using numerical and experimental tools. An existing Combined Finite-Discrete element (FEM/DEM) code was extended to suit heterogeneous, discontinuous, brittle rocks. By conducting grid micro-indentation and micro-scratch tests, the Young's modulus and fracture toughness of the constituent phases of the rock were obtained and used as accurate input parameters for the numerical models. The models incorporated the exact phase mapping obtained from a MicroCT-scanned specimen and the existing microcrack density obtained from thin section analysis. The results illustrated that by incorporating accurate micromechanical input parameters and the intrinsic rock geometric features, the numerical simulations could more accurately predict the mechanical response of the specimen, including the fracture patterns and tensile strength. The numerical simulations illustrated that microstructural flaws such as microcracks should be included in the models to more accurately reproduce the rock strength. In addition, the differential elastic deformations caused by rock heterogeneity altered the stress distribution in the specimen, creating zones of local tensile stresses, in particular, on the boundaries between different mineral phases. As a result, heterogeneous models exhibited rougher fracture surfaces. MicroCT observations emphasized the influence of heterogeneity and, in particular, biotite grains on the fracture trajectories in the specimens. Favourably oriented biotite flakes and cleavage splitting significantly deviated the cracks. The interaction of the main crack with perpendicular cleavage planes of biotite caused strong crack deviation and termination. Considering heterogeneity and the strength degradation caused by microcracks, the simulations captured reasonably accurate mechanical responses and failure mechanisms for the rock, namely, the nonlinear stress-strain relationships. The insights presented in this study improve the understanding of the role of heterogeneity and microstructure on damage and mechanical behaviour of brittle rock.

The mechanical response of geomaterials is highly influenced by geometrical and material heterogeneity. To date, most modelling practices consider heterogeneity qualitatively and the choice of input parameters can be subjective. In this study, a novel approach to combine detailed micro-scale characterization with modelling of heterogeneous geomaterials is presented. The influence of micro-scale heterogeneity and microcracks on the mechanical response and brittle fracture of a crystalline rock was studied using numerical and experimental tools. An existing Combined Finite-Discrete element (FEM/DEM) code was extended to suit heterogeneous, discontinuous, brittle rocks. By conducting grid micro-indentation and micro-scratch tests, the Young's modulus and fracture toughness of the constituent phases of the rock were obtained and used as accurate input parameters for the numerical models. The models incorporated the exact phase mapping obtained from a MicroCT-scanned specimen and the existing microcrack density obtained from thin section analysis. The results illustrated that by incorporating accurate micromechanical input parameters and the intrinsic rock geometric features, the numerical simulations could more accurately predict the mechanical response of the specimen, including the fracture patterns and tensile strength. The numerical simulations illustrated that microstructural flaws such as microcracks should be included in the models to more accurately reproduce the rock strength. In addition, the differential elastic deformations caused by rock heterogeneity altered the stress distribution in the specimen, creating zones of local tensile stresses, in particular, on the boundaries between different mineral phases. As a result, heterogeneous models exhibited rougher fracture surfaces. MicroCT observations emphasized the influence of heterogeneity and, in particular, biotite grains on the fracture trajectories in the specimens. Favourably oriented biotite flakes and cleavage splitting significantly deviated the cracks. The interaction of the main crack with perpendicular cleavage planes of biotite caused strong crack deviation and termination. Considering heterogeneity and the strength degradation caused by microcracks, the simulations captured reasonably accurate mechanical responses and failure mechanisms for the rock, namely, the nonlinear stress-strain relationships. The insights presented in this study improve the understanding of the role of heterogeneity and microstructure on damage and mechanical behaviour of brittle rock.

The mechanical properties of biomaterials play important roles in performing their specialized functions: synthesizing, storing, and transporting biomolecules; maintaining internal structures; and responding to external environments. Besides biological cells, there are also many other biomaterials that are highly deformable and have a diameter between 1μm and 100μm, comparable to that of most biological cells. For example, many polymeric microcapsules for drug delivery use are spherical particles of micrometers size. In order to mechanically characterize individual micrometer-sized biomaterials, the capability of capturing high-resolution and low-magnitude force feedback is required. This research focuses on the development of micro devices and experimental techniques for quantifying the mechanical properties of alginate-chitosan microcapsules. The micro devices include microelectromechanical systems (MEMS) capacitive force sensors and force-feedback microgrippers, capable of measuring sub-μN forces. Employing the MEMS devices, systems were constructed to perform the micro-scale compression testing of microcapsules. The force sensors are capable of resolving forces up to 110μN with a resolution of 33.2nN along two independent axes. The force sensors were applied to characterizing the mechanical properties of hydrogel microparticles without assembling additional end-effectors. The microcapsules were immobilized by a PDMS holding device and compressed between the sensor probe and holding device. Young's modulus values of individual microcapsules with 1%, 2%, and 3% chitosan coating were determined through the micro-scale compression testing in both distilled deionized (DDI) water and pH 7.4 phosphate buffered saline (PBS). The Young's modulus values were also correlated to protein release rates. Instead of compressing the microcapsule against the wall of the holding device, a force-feedback MEMS microgripper with the capability of directly compressing the microcapsule between two gripping arms has been used for characterizing both the elastic and viscoelastic properties of the microcapsules during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified the Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.

Chip scale refrigeration system is critical for the development of electronics with the rapid increase of power consumption and substantial reduction of device size, resulting in an emergent demand on novel cooling technologies with a high efficiency for the thermal management. In this thesis, active refrigeration devices based on Stirling cycle and an electrocaloric material, are designed and investigated to achieve a high cooling performance. Firstly, a new Stirling micro-refrigeration system composed of arrays of silicon MEMS cooling elements is designed and evaluated. The cooling elements are fabricated in a stacked array on a silicon wafer. A regenerator is placed between the compression (hot side) and expansion (cold side) diaphragms, which are driven electrostatically. Under operating conditions, the hot and cold diaphragms oscillate sinusoidally and out of phase such that heat is extracted to the expansion space and released from the compression space. A first-order of thermodynamic analysis is performed to study the effect of geometric parameters. Losses due to regenerator non-idealities and chamber heat transfer limitation are estimated. A multiphysics computational approach for analyzing the system performance that considers compressible flow and heat transfer with a large deformable mesh is demonstrated. The optimal regenerator porosity for the best system COP (coefficient of performance) is identified. To overcome the computational complexity brought about by the fine pillar structure in the regenerator, a porous medium model is used to allow for modeling of a full element. The analysis indicates the work recovery of the system and the diaphragm actuation are main challenges for this cooler design.The pressure drop and friction factor of gas flow across circular silicon micro pillar arrays fabricated by deep reactive ion etch (DRIE) process are investigated. A new correlation that considers the coupled effect of pillar spacing and aspect ratio, is proposed to predict the friction factor in a Reynolds v number range of 1-100. Silicon pillars with large artificial roughness amplitudes is also fabricated, and the effect of the roughness is studied in the laminar flow region. The significant reduction of pressure drop and friction factor indicates that a large artificial roughness could be built for pillar arrays in the regenerator to enhance the micro-cooler efficiency. The second option is to develop a fluid-based refrigeration system using an electrocaloric material poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer. Each cooling element includes two diaphragm actuators fabricated in the plane of a silicon wafer, which drive a heat transfer fluid back and forth across terpolymer layers that are placed between them. Finite element simulations with an assumption of sinusoidal diaphrahm motions are conducted to explore the system performance detailedly, including the effects of the applied electric field, geometric dimensions, operating frequency and externally-applied temperature span. Multiphysics modeling coupled with solid-fluid interaction, heat transfer, electrostatics, porous medium and moving mesh technique is successfully performed to verify the thermal modeling feasibility. The electrocaloric effect in thin films of P(VDF-TrFE-CFE) terpolymer is directly measured by infrared imaging at ambient conditions. At an electric field of 90 V/μm, an adiabatic temperature change of 5.2 °C is obtained and the material performance is stable over a long testing period. These results suggest that application of this terpolymer is promising for micro-scale refrigeration.