Dissertationen zum Thema „Separation“

Proteins have been extensively studied over the last decade as comprehensive understanding of the proteome can definitely lead to the discovery of novel biomarkers, early-stage disease diagnoses and the development of diagnostic tools and novel drug therapies. One of the crucial and fundamental processes in protein analysis is protein separation, which is usually performed as multidimensional separations to achieve high resolution and high peak capacity. However, high performance analyses are difficult to achieve due to the challenges involved in efficiently integrating different dimensions. In this work, we present the development of a microfluidic device for the effective transfer of protein droplets into the second separation dimension. Consequently, the device provides a stable, reproducible, easy to operate, portable and flexible system to connect a first dimension separation to the downstream second dimension analysis via droplets. The droplets act to preserve the resolution during transfer between separation techniques. In summary, a fluorescently labeled protein ladder serving as a representative of proteins separated from the first dimension is compartmentalized into droplets using the robotic droplet generator. These protein droplets are then transferred via the interfacing microdevice into the second dimension where the released proteins are further separated using capillary gel electrophoresis. Herein, several designs of interfacing microdevices were evaluated for the successful transfer of droplet contents (droplet injection) into the second dimension. The buffer for capillary gel electrophoresis was developed to achieve high-speed and high-resolution separations of proteins in droplet-based injection format. Several fluorescent dyes were also examined for protein labeling to achieve high fluorescent intensities necessary when using this droplet format. Successful droplet-based separation of proteins necessitates the seamless integration of all the developed components. This has been demonstrated here. This interface automates the oil depletion process, minimizes dead volume, prevents dispersion of analyte bands and reduces sample loss at the interface between separation dimensions. Furthermore, optimization of the entire system used in conjunction with the interfacing microdevice provided for ease of operation and more efficient droplet injections. Moreover, droplet injection into parallel separation channels was achieved, highlighting the interfaces capacity for high-throughput analyses.

Conventional bulk oil-water separation is performed in large gravity separators that take up large areas and potentially contain large volumes of hazardous material. An intensified bulk separator has the potential to provide significant benefit in saving space, especially where this is at a premium, and in improving safety. The I-SEP, a novel geometry of Axial-Flow Cyclone (also known as Uniflow or straight-through) separator, has been tested as an intensified bulk oil-water separator. The objective of this work is to quantify performance by producing a map of separation performance with variation of inlet conditions, using variation of outlet back pressure to make the separator adaptable to variable inlet flow. A second objective is to compare the experimental performance of the I-SEP with a mathematical model. Using a Perspex test-unit with kerosene, or a silicone-based oil, and water in a batch flow loop, a map has been produced for outlet compositions and separation efficiencies at multiple inlet velocities. This was done for a range of inlet water cuts from 10% to 90% and with a geometry varied by lengthening the separating chamber of the test unit. A Computational Fluid Dynamics model using the Reynolds-Stress model has been developed with the FLUENT 6.0 CFD code. This has been compared with quantitative flow visualisation data and drop sizing information to model the separation of the cyclone by a discrete-phase technique. An optimum configuration and operating conditions has been found, with peak efficiencies in excess of 80%. This shows the important effect in improving performance achieved by the manipulation of outlet flow splits using backpressure. This Axial-Flow Cyclone design achieves a broader range of separation effect than published Reverse-Flow Cyclone designs. However, the unit will need to undergo further development to reduce shear and maximise residence time at high swirl.

Separation Mitt projekt rör sig kring temat separation, separation av funktioner, separation i fysisk bemärkelse och separation av människor. Jag spenderade mycket tid åt att undersöka kreamtoriet som anläggning, dess programdelar och platsen som vi fått till förfogande. Hela tiden rörde sig undersökningen tillbaka till separation, krematoriets funktionsseparering, åtskillnaden av industri och ceremoni. Jag valde att använda detta som en språngbräda för projektet. Krematoriet är som byggnad tydligt indelad i olika funktioner som försöker distansiera sig från varandra, den industriella och den ceremoniella, men även den del av programmet som berör personalen då de inte är i arbete. Tre olika funktioner som drar i olika riktningar, så jag började fundera över om jag ville arbeta för att överbrygga eller förstärka denna separation och hur detta skulle kunna representeras fysiskt fysiskt genom en byggnad. Tidigt i den undersökningen insåg jag att det var förstärknigen av det rådande förhållandet mellan funktionerna och rummen som jag ville arbeta med. När jag sedan började arbeta med formen började jag därför med att dela upp programmet i tre olika volymer och försökte få dem att förhålla sig till varandra utan att förenas till en helhet. Av praktiska skäl (för personalen) så valde jag istället att försöka få in tydligt separerade funktioner i en dammanhängade byggnad. Här kom ideén att använda mig av ett förvrängt gridsystem för att generera spännande former ch samtidigt uppfylla min strävan efter rum som fysiskt ger sken av att försöka separera sig från varandra. Resultatet är mitt krematorium, som bygger på ett rutnät på1500x1500mm soms edan har manipulerats genom att jag dragit de trte huvudfunktionerna i olika riktning. att komma fram till en metod för att förvränga gridet på ett sätt som inte blev helt och hållet godtyckligt var en lång process. Först ville jag att sträckan mellan punkterna i gridet skulle vara konstant och att bara mötespunkterna skulle förändras. Jag testade detta i modell, med ett intressant resultat men när jag sedan försökte mig på samma sak digitalt så visade det sig ganska snabbt att det fanns mycket begränsade möjligheter. Så jag valde slutligen att låta sträckan mellan punkterna vara flexibla och behandla gridet genom att låta punkterna flyttas utefter ett förutbestämt mönster. Då min byggnad är så tydligt format av det förvrängda gridet så ville jag visa upp det även för besökaren och då det hade varit omöjligt att låta alla punkter bli pelare av användningstekniska skäl så fick vissa punkter bli pelare, andra rumsskapande Byggnadens struktur består både av bärande väggar och pelare som är utplacerade enligt det bestämda gridet. Materialen som används i strukturen är i huvudsak massivträ, förutom i källarplanet och i de väggar om omsluter ugnshallen. Innerväggarna är obeklädda och materialet på interiören är därmed samma som i strukturen. Förutom de bärande pelarna återfinns även en mängd tunnare pelare som finns till enbart för atmosfärens skull. hela projektet är en process & en undersökning av hur man kan arbeta med gridsystem och hur man arbetar med och överbrygger de begränsningar som ett bestämt systen medför. En undersökning i att sätta upp striktearegler för sig själv och att sedan våga ta steget att bryta dem när man måste.
Separation This project follows a theme of separation, separation of functions, fysical separation and separation of people. A Chrematory is in its nature in a constant state of conflict, very different and complicated functions forced together into the same building, functions wich are trying to move in away from each other, trying to separate. There are basically three different parts of the chrematory, the industrial side, the part for the family an friends of the diseaced and the parts for the employes. All with verya specific demands and different atmospheres. I Wanted to enhance this state of separation between the functions but still keep them in the same building and i came up with a strategi to make that possible. I was going to use a distorted grid system to let the separation show in the built form. The project became a study of grids, how you can distort them in diferent ways and how you can use them to create different atmospheres and interesting forms. But also a study of how to make strict rules for yourself, how to keep them, and work with the difficulties you face when you have these rules to follow. And last but not least how to learn how to break your own rules when they have to be broken.

Cyclone separators have been described in detail and, although substantial research has been performed on solid / gas devices, the use of cyclones for gas / liquid separation has been comparatively ignored; this is particularly true for higher concentrations of liquid and for degassing applications. Consequently no generic models are available which will predict separation efficiency or pressure drop for all designs of cyclone. A novel design of axial flow cyclone called WELLSEP was examined for the purpose of degassing. This design was not believed to be optimal and no design criteria or performance prediction models were available for it. An experimental programme was therefore produced and executed to investigate changes in geometry and the affect of fluid dynamics. Changes to the length, vortex finder and swirl generator were examined first and then one design was selected and tested over a number of liquid flow rates, Gas Void Fractions (GVFs) and liquid extractions. Data was collected from the experiments which assisted in the development of semi-empirical models for the prediction of pressure drop and separation efficiency. These models could be used in the design of WELLSEP. Geometric and fluid dynamics changes have both been shown to influence the performance of the tested cyclone. The principal conclusions that have been drawn from this research are: " Of the tested designs, the design based upon a 30mm vortex finder diameter, settling chamber length of three times the diameter of the cyclone and a four start helix gave the optimum separation efficiency over the greatest range of conditions. 0 The separation efficiency is affected by the superficial liquid velocity and the liquid extraction but not the GVF. " The dimensionless pressure drop coefficient (Euler number) is a function of liquid extraction and GVF. It may also be a function of the superficial liquid velocity but it is unproven by this research.

Identified as an important issue for marginal fields, the removal of sand from hydrocarbon fluids has been investigated. A review of existing sand separation equipment has recognized a need for a new separator which will satisfy the design and performance requirements necessary for protecting offshore processing equipment. This thesis details the work and analysis undertaken which has contributed towards the design and development of a new offshore gas/solid separator. A critique of different separation techniques has identified axial flow cyclone (AFC) separators as a suitable separator design for offshore desanding applications. After reviewing existing models which simulate the performance of AFC separators a simple classification table has been developed. Using the conclusions of this review as a starting platform, a methodology for developing a new computational fluid dynamics (CFD) performance model for the new separator was proposed. Experimental work undertaken at the CALtec laboratories and the BG plc (formerly British Gas Research and Technology) Low Thornley test facilities are presented. The results obtained have been used to analysis the performance of difference separator internal designs. In addition, the results have been used to evaluate the robustness of existing AFC performance models and validate the new CFD model. For the investigated operational duties, the new CFD model has been shown to consistently under-predict the collection efficiency, whereas the other AFC models over-predict. From a design point of view, a model which under-predicts the overall collection efficiency will result in the over-design of the separator for a particular operating duty. Therefore, the use of such a model will ensure the design of a separator which will offer greater than expected levels of protection of downstream equipment from erosion wear.

The problem of signal separation is a very broad and fundamental one. A powerful paradigm within which signal separation can be achieved is the assumption that the signals/sources are statistically independent of one another. This is known as Independent Component Analysis , (ICA). In this thesis, the theoretical aspects and derivation of ICA are examined, from which disparate approaches to signal separation are drawn together in a unifying framework. This is followed by a review of signal separation techniques based on ICA. Second order statistics based output decorrelation methods are employed to try to solve the challenging problem of separating convolutively mixed signals, in the context of mainly audio source separation and the Cocktail Party Problem. Various optimisation techniques are devised to implement second order signal separation of both artificially mixed signals and real mixtures. A study of the advantages and limitations of decorrelation methods is made and some theoretical insights are drawn into a major identifiability problem associated with convolutive source separation using second order statistics only. Motivated by the fact that many signals in real life, especially audio signals, exhibit large degrees of non-stationarity, decorrelation algorithms that take into consideration aspects of non-stationarity are devised. Next, a model based approach to source separation is considered. The problem of non-stationary ICA (nsICA) is addressed, where the mixing system is scalar but time-varying. The density of the sources are modelled as finite mixtures of Gaussians. Simulation based Bayesian methods, notably Markov Chain Monte Carlo (MCMC) techniques, are employed to separate both synthetic and real data that have been mixed by non-stationary mixing matrices. Satisfactory results have been obtained with very few data points, using batch methods, such as Gibbs sampling. The techniques of Sequential Monte Carlo (SMC) methods, or particle filtering, are employed to this problem as well, in the context of both blind and semi-blind signal separation, which involve tracking the time varying mixing system.

Separation anxiety is one of the most common behavioral disorder in companion dogs. Dogs not suffering from separation anxiety may still exhibit separation-related behaviors, which can differ depending on environmental contexts. In the present study, dogs without separation-related problems were video recorded during a short separation (3 min) from, and during reunion with, their owner. Comparison was done between if the dogs had played or been calm pre-separation. The dogs spent most time in proximity to the entrance and gazing towards where the owner left during separation. Their body-position was mostly standing, followed by sitting. All dogs were wining during separation, which occurred approximately four times more than barking. Dogs that had played pre-separation were running around more and had a longer latency to the first movement, compared to when they had been calm pre-separation. During reunion, when dogs had played pre-separation, they wagged their tail more and had a longer latency to lip licking, compared to when they had been calm pre-separation. The separation behaviors that occurred in this study aligns with previous work in this subject. Furthermore, one can suggest that play pre-separation might have an effect on separation behaviors, where speculations can be done if the positive affect associated with play might be the underlying cause for these findings.

Polyhedral foams offer large gas-liquid interfacial area associated with a small amount of liquid. Therefore, if a solute adsorbs preferentially at the interface, the concentration of the solute in the foam will be greater than in the solution from which the foam has been generated. This effect provides a simple method of concentrating materials which have a tendency to adsorb on the gas-liquid interface. This is particularly relevant to biomaterials like whole cells, proteins, enzymes etc., which are surface active and are present in low concentrations in the broth. Foam separation has therefore attracted considerable attention, and several reports exist in literature on concentrating cells, proteins and enzymes using foams. Foam separation is based on the difference in surface activity of the components to be separated. A surface active molecule consists of a lyophobic and a lyophilic group. (As water is commonly used as a solvent, the lyophilic and lyophobic groups are called hydrophilic and hydrophobic groups, respectively). When dissolved in a solvent, the presence of lyophobic groups in the interior of the solvent distorts the solvent liquid structure, thereby increasing the free energy of the system.

Polyhedral foams offer large gas-liquid interfacial area associated with a small amount of liquid. Therefore, if a solute adsorbs preferentially at the interface, the concentration of the solute in the foam will be greater than in the solution from which the foam has been generated. This effect provides a simple method of concentrating materials which have a tendency to adsorb on the gas-liquid interface. This is particularly relevant to biomaterials like whole cells, proteins, enzymes etc., which are surface active and are present in low concentrations in the broth. Foam separation has therefore attracted considerable attention, and several reports exist in literature on concentrating cells, proteins and enzymes using foams. Foam separation is based on the difference in surface activity of the components to be separated. A surface active molecule consists of a lyophobic and a lyophilic group. (As water is commonly used as a solvent, the lyophilic and lyophobic groups are called hydrophilic and hydrophobic groups, respectively). When dissolved in a solvent, the presence of lyophobic groups in the interior of the solvent distorts the solvent liquid structure, thereby increasing the free energy of the system.

The separation of independent sources from mixed observed data is a fundamental and challenging signal processing problem. In many practical situations, one or more desired signals need to be recovered from the mixtures only. A typical example is speech recordings made in an acoustic environment in the presence of background noise and/or competing speakers. Other examples include EEG signals, passive sonar applications and cross-talk in data communications. The audio signal separation problem is sometimes referred to as The Cocktail Party Problem. When several people in the same room are conversing at the same time, it is remarkable that a person is able to choose to concentrate on one of the speakers and listen to his or her speech flow unimpeded. This ability, usually referred to as the binaural cocktail party effect, results in part from binaural (two-eared) hearing. In contrast, a person with a severe hearing loss in one ear finds it is difficult to focus on a particular speaker under the same circumstances. A signal separation pre-process would be desirable in such circumstances. Signal separation techniques can also be applied in many other areas such as noise reduction, speech recognition and multi-media applications. The term 'Blind Signal Separation' refers to the lack of any propagation model: only statistical independence of the sources is assumed. The lack of other prior information underlines the difficulty of the problem. Observations may be modelled as linear mixtures of a number of source signals, i.e. a linear multi-input multi-output system. In this dissertation, the general n-source n-sensor (n x n) linear time invariant wide-band system is studied, in which, n random signals are received at n sensors and these signals originated from n sources. The problem is to recover the sources from observed signals only. Various block-based iterative algorithms are proposed which use output decorrelation as a signal separation criterion. These algorithms search for a linear transformation that minimises the statistical correlation between the components. Some existing solutions are reviewed and compared.

This thesis presents structural separation logic, a novel program reasoning approach for software that manipulates both standard heaps and structured data such as lists and trees. Structural separation logic builds upon existing work in both separation logic and context logic. It considers data abstractly, much as it is exposed by library interfaces, ignoring implementation details. We provide a programming language that works over structural heaps, which are similar to standard heaps but allow data to be stored in an abstract form. We introduce abstract heaps, which extend structural heaps to enable local reasoning about abstract data. Such data can be split up with structural addresses. Structural addresses allow sub-data (e.g. a sub-tree within a tree) to be abstractly allocated, promoting the sub-data to an abstract heap cell. This cell can be analysed in isolation, then re-joined with the original data. We show how the tight footprints this allows can be refined further with promises, which enable abstract heap cells to retain information about the context from which they were allocated. We prove that our approach is sound with respect to a standard Hoare logic. We study two large examples. Firstly, we present an axiomatic semantics for the Docu- ment Object Model in structural separation logic. We demonstrate how structural separa- tion logic allows abstract reasoning about the DOM tree using tighter footprints than were possible in previous work. Secondly, we give a novel presentation of the POSIX file system library. We identify a subset of the large POSIX standard that focuses on the file system, including commands that manipulate both the file heap and the directory structure. Axioms for this system are given using structural separation logic. As file system resources are typically identified by paths, we use promises to give tight footprints to commands, so that that they do not require all the resource needed to explain paths being used. We demonstrate our reasoning using a software installer example.

The objective of this work has been to investigate the principle of combined bioreaction and separation in a simulated counter-current chromatographic bioreactor-separator system (SCCR-S). The SCCR-S system consisted of twelve 5.4cm i.d x 75cm long columns packed with calcium charged cross-linked polystyrene resin. Three bioreactions, namely the saccharification of modified starch to maltose and dextrin using the enzyme maltogenase, the hydrolysis of lactose to galactose and glucose in the presence of the enzyme lactase and the biosynthesis of dextran from sucrose using the enzyme dextransucrase. Combined bioreaction and separation has been successfully carried out in the SCCR-S system for the saccharification of modified starch to maltose and dextrin. The effects of the operating parameters (switch time, eluent flowrate, feed concentration and enzyme activity) on the performance of the SCCR-S system were investigated. By using an eluent of dilute enzyme solution, starch conversions of up to 60% were achieved using lower amounts of enzyme than the theoretical amount required by a conventional bioreactor to produce the same amount of maltose over the same time period. Comparing the SCCR-S system to a continuous annular chromatograph (CRAC) for the saccharification of modified starch showed that the SCCR-S system required only 34.6-47.3% of the amount of enzyme required by the CRAC. The SCCR-S system was operated in the batch and continuous modes as a bioreactor-separator for the hydrolysis of lactose to galactose and glucose. By operating the system in the continuous mode, the operating parameters were further investigated. During these experiments the eluent was deionised water and the enzyme was introduced into the system through the same port as the feed. The galactose produced was retarded and moved with the stationary phase to be purge as the galactose rich product (GalRP) while the glucose moved with the mobile phase and was collected as the glucose rich product (GRP). By operating at up to 30%w/v lactose feed concentrations, complete conversions were achieved using only 48% of the theoretical amount of enzyme required by a conventional bioreactor to hydrolyse the same amount of glucose over the same time period.

When launching a satellite a separation system is used to keep the satellite attached to a launch vehicle during ascent and to separate it from the launch vehicle while in space. In separation analysis the separation is studied by simulations to see if requirements on the system can be fulfilled. The purpose of this master’s thesis is to investigate if separation analysis can be done using the modeling program OpenModelica and to evaluate OpenModelica and compare it to other modeling programs.

OpenModelica is free software implementing the Modelica language, which is an object-oriented language for modeling and simulation of complex physical systems. Modelica uses equation-based modeling, this means that the physical behaviour of a model is described by differential, algebraic and discrete equations and no particular variable needs to be solved manually.

The work is divided into two parts. The main part is to implement a mathematical model of a separation system in OpenModelica, simulate it and study the behaviour of the system. A Monte Carlo method, which randomly generates values for uncertain model parameters, is used when simulating the model. The other part of the work is to evaluate OpenModelica and compare it with other modeling programs, such as Matlab/Simulink, C/C++ and JAVA to see advantages and disadvantages with OpenModelica.

How should n points be distributed in a given region F in R^d such that they are separated as much as possible? This general problem is studied in this paper, for some combinations of F, d, n, and the ways one can state the problem mathematically. Some numerical optimization methods are suggested and tested, both on the point separation problem and the closely related circle packing problem. The results are compared with some known analytical results. The main conclusion is that the suggested numerical methods are useful general tools to obtain optimal solutions to the considered problems.

To offset rising energy costs, it is becoming a necessity to lower energy usage within industrial processes. Such can be said for the separation of olefin/paraffin mixtures. An example of such a mixture is ethylene/ethane. This highly energy intensive industrial separation employs cryogenic distillation to achieve a high purity product. Subsequently, the energy cost to run such a system is extremely high. Hybrid scenarios have been explored, with adsorption being a potential candidate. This work studied the potential of three adsorbents for the separation of ethylene/ethane: AgNO3/SiO2, CuCl/SiO 2, and CECA 13X. AgNO3/SiO2 and CuCl/SiO 2 were both prepared in the laboratory. Pure component constant volume experiments were conducted, along with binary mixture predictions for all three adsorbents at 3 different temperatures. The expected working capacities were also calculated for the three adsorbents. Finally, an economic analysis, without taking competitive adsorption in to factor, was conducted to give a rough idea of how much a potential PSA system would cost using the three adsorbents individually. CuCl/SiO2 yielded the most favorable results of the three adsorbents, but more studies were determined necessary on the optimization of the preparation of the adsorbent. AgNO3/SiO 2 was not completely ruled out, however. Both the adsorbents showed characteristics for a potential use within industry. CECA 13X was not considered a viable candidate for such a separation.

Reverse-micelles are surfactant aggregates in an apolar solvent. The surfactants, which must have two hydrophobic tails, cluster around a water core. The effects of the compositions of the solvent and the aqueous phase on water solubilization were studied for two anionic surfactants: sodium di-2-ethylhexylsulfosuccinate (AOT) and dinonylnaphthalene sulfonic acid (DNNSA). Single straight chain alkanes having 6-17 carbons, mixtures of these alkanes and branched alkanes were used as solvents. The aqueous phases consisted of salts and buffers.
For AOT in straight chain alkanes, water uptake increased as the length of the chain approached 9 carbons, the length of the AOT hydrocarbon tail. As the solvent length increased further, a critical carbon number was reached above which there was no water uptake. Different buffers shifted the critical carbon number somewhat. Mixtures of straight chain alkanes behaved similar to single alkanes when compared on the basis of volume-average carbon number. Branched alkanes solubilized more water than their straight chain isomers. For DNNSA the water uptake was the same for all solvents.

Consider the following fundamental problem: given two sets R and G of objects positioned in d-dimensional Euclidean space, does there exist a surface of some specific type which separates the objects of R from the objects of G?
Much attention has been given to this problem, for many classes of objects and separating surfaces. However, very few satisfactory alternatives exist when the objects are not separable by any of the surfaces of the chosen class. In this thesis, a new combinatorial measure of separability is proposed, based on the largest subset of the objects in $R cup G$ that may be separated using surfaces drawn from a certain class. The combinatorial and algorithmic questions arising from this weak separation measure are the main focus of the thesis. The strong relationship between the separable subsets of point sets and faces of hyperplane arrangements is investigated, and a variety of algorithms are presented for finding linear and spherical separators for point sets and sets of hyperspheres.

The last 10 years have presented the Marine Corps with the challenge of continuous deployments to hostile environments at an unprecedented rate. This study examines the correlation between deployment tempo and medical separation rates for Marines who have shown an intention to remain in the Service by reenlisting past their first term. It does so by comparing the probability of medical separation for careerists relative to other causes of separation. The data comes from the Marine Corps Total Data Force Warehouse. Interaction effects were measured using a Linear Probability Model and probit estimations. Key variables in my study are gender, a 9/11 partition, and the number of deployments. Medical separations are defined as acute sources, such as loss of limb, degenerative sources such as back pain and other long-term ailments, and medical retirements. Among those separated, I find that the increased deployment tempo in the post- 9/11 era leads to decreases in medical separation rates, particularly among those with two or more deployments. There is also a notable additional decrease in medical separation for female Marines who have deployed.

Static program analysis can improve programmer productivity and software reliability by definitively ruling out entire classes of programmer mistakes. For mainstream imperative languages such as C, C++, and Java, static analysis about the heap---memory that is dynamically allocated at run time---is particularly challenging because heap memory acts as global, mutable state. This dissertation describes how to soundly combine two static analyses that each take vastly different approaches to reasoning about the heap: type systems and separation logic. Traditional type systems take an alias-agnostic, global view of the heap that affords both fast verification and light-weight annotation of invariants holding over the entire program. Separation logic, in contrast, provides an alias-aware, local view of the heap in which invariants can vary at each program point. In this work, I show how type systems and separation logic can be safely and efficiently combined. The result is type-intertwined separation logic, an analysis that applies traditional type-based reasoning to some regions of the program and separation logic to others---converting between analysis representations at region boundaries---and summarizes some portions of the heap with coarse type invariants and others with precise separation logic invariants. The key challenge that this dissertation addresses is the communication and preservation of heap invariants between analyses. I tackle this challenge with two core contributions. The first is type-consistent summarization and materialization, which enables type-intertwined separation logic to both leverage and selectively violate the global type invariant. This mechanism allows the analysis to efficiently and precisely verify invariants that hold almost everywhere. Second, I describe gated separating conjunction, a non-commutative strengthening of standard separating conjunction that expresses local dis-pointing relationships between sub-heaps. Gated separation enables local heap reasoning by permitting the separation logic to frame out portions of memory and prevent the type system from interfering with its contents---an operation that would be unsound in type-intertwined analysis with only standard separating conjunction. With these two contributions, type-intertwined separation logic combines the benefits of both type-like global reasoning and separation-logic-style local reasoning in a single analysis.

The effective separation of ammonia from the synthesis loop in ammonia synthesis plants is an important step in its manufacture. This work presents the use of nanocomposite MFI zeolite membranes prepared by a pore-plugging method for this separation process. Performance of a zeolite membrane is highly dependent on the operating conditions. Therefore, the influences of differential pressure, temperature, sweep gas flow, feed gas flow and gas composition are studied experimentally. Transport of NH3 in this membrane is by surface diffusion in the intracrystalline (zeolite) pores in parallel with capillary condensation in the intercrystalline (non-zeolite) pores. The separation of NH3 from a mixture with H2 and N2 is by preferential adsorption of NH3, which hinders the permeation of weakly adsorbed H2 and N2. Differential pressure has only relatively small effects in the pressure range 300kPa – 1550kPa. Increase in sweep flow rate has little effect on NH3 gas permeance, but H2 and N2 permeances increase thereby decreasing the selectivities. Increase in feed flowrate also has little effect on NH3 permeance. However, the N2 and H2 permeances increase and there is a subsequent decrease in selectivities. Membrane performance was found to be highly dependent on temperature. NH3 permeance in the mixture increases linearly with temperature. NH3 selectivity was found to increase with temperature up to 353K after which it starts to decrease due to N2 and H2 permeances increasing with temperatures beyond 353K (αNH3/N2 = 46 and αNH3/H2 = 15) and is therefore the optimum temperature for separation. A potential barrier model is developed to describe the hindering effect of NH3 on H2 and N2 permeance. The model fails to predict correctly H2 and N2 permeances in the ternary mixture using pure gas (H2 and N2) permeances. Binary mixture permeation H2/N2 studies showed that there are diffusion effects (single file diffusion) that have not been taken into account in the potential barrier model. When permeances of the individual components in the binary mixture are used in the model instead of the pure gas permeances, there is an improved agreement between experimental and predicted results.

Thesis (MScEng)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Pure primary alcohols are very valuable as raw materials and solvents. Close-boiling alcohol mixtures are produced as byproducts from the Fischer Tropsch synthesis. These byproducts include the mixtures 1-butanol+2- penta noI and 1-pentanol+2-hexanol. Due to the small difference in boiling points these alcohols cannot be separated from one another by using conventional distillation. This study has been undertaken to determine whether primary and secondary alcohols may be separated by exploitation of their chemical properties. Esterification of the alcohols followed by distillation of the esters into cuts and hydrolyses of the esters, has been attempted to separate the alcohols. This however, was unsuccessful. In this study the difference in dehydration rate of secondary and primary alcohols in acidic media has also been investigated. Several acidic resins and liquid catalysts have been used. The acidic resins gave no dehydration or extremely low dehydration rates in the liquid phase. The liquid catalysts H2S04, Oxalic Acid, NaHS04 and H3P04 were investigated. H3P04 gave excellent results. Laboratory experiments were conducted at the boiling point of the reaction mixture at atmospheric pressure. The reaction mixture was sampled at varying time intervals and analysed. The secondary alcohol dehydrated rapidly to the corresponding alkene. The primary alcohol formed symmetrical ethers at a very low rate. The primary and secondary alcohol also combined to form small amounts of unsymmetrical ethers. After the dehydration reaction the organic products can be separated from the acid with a'short path distillation unit. The primary alcohol can further be purified by conventional distillation. Conceptual process designs were done for the separation and purification of the reactor product streams of the alcohol mixtures 1-butanol+2-pentanol and 1-pentanol+2-hexanol. n laboratory scale it was found that for the separation of 85% 1-butanol and 15% 2-pentanol (mass %), 90 % H3P04 (mass %) at an acid:alcohol ratio of 1,5: 1 results in suffcient dehydration of 2-pentanol. A reaction time of 70 minutes is required. A conceptual design on the purification of the 1-butanol predicted a product quality of 99,5 % 1-butanol (mass %) and a 1-butanol recovery of 75 %. The 1-butanol recovery is low, because a major part of the 1-butanol is lost in the purification as part of the ternary azeotrope with water and n-butylether. On laboratory scale it was also found that for the separation of 85 % 1- pentanol+15 % 2-hexanol (mass %),90 % H3P04 (mass %) at an acid:alcohol ratio of 1,5:1 gives sufficient dehydration of 2-hexanol. A reaction time of only 35 minutes is required. A conceptual design on the purification of the 1- pentanol predicted a product quality of 99,9 % 1-pentanol and a 1-pentanol recovery of > 98 %. The 1-pentanol recovery is excellent, only the 1- pentanol that is converted to ethers is lost. In this study it has been proven that a dehydration separation process can be applied successfully to remove secondary alcohols from a primary+secondary alcohol mixture. Especially the removal of 2-hexanol from a 1-pentanol+2- hexanol mixture gave promising results. In order to assess the economic viability of this dehydration process an economic evaluation should be done. This could be part of subsequent studies. The dehydration separation process should be investigated further. It is believed that this dehydration separation process can be expanded to higher alcohols, e.g. 1-hexanol+2-heptanol. It would be extremely advantageous if a solid catalyst could be found for the separation. In this case the recovery of the organics from the reaction mixture would be very much easier. If a solid catatyst is not found, a continuous process using H3P04 as liquid catalyst should be developed.
AFRIKAANSE OPSOMMING: Suiwer primêre alkohole is baie waardevolle rou materiale en oplosmiddels. Alkohol mengsels, wat uit naby-kokende alkohole bestaan, word as neweprodukte in die Fischer Tropsch Sintese gevorm. Hierdie newe-produkte sluit alkohol mengsels soos 1-butanol+2-pentanol en 1-pentanol+2-hexanol in. Weens die klein verskil in kookpunte van hierdie alkohole kan die alkohole nie met konvensionele distillasie van mekaar geskei word nie. Hierdie studie is onderneem om te bepaal of die chemiese eienskappe van alkohole benut kan word om primêre en sekondêre alkohole van mekaar te skei. 'n Poging is aangewend om die alkohole met behulp van esterifikasie te skei. Die alkohole is eers ge-esterifiseer, daarna met behulp van distillasie in verskeie snitte verdeel en die alkohol is vrygestel deur hidrolise van die esters. Dit was egter onsuksesvol. Die verskil in dehidrasie tempo van sekondêre en primêre alkohole in suur mediums is ook ondersoek. Verskeie suur harse en vloeibare kataliste is ondersoek. Die suur .harse het of geen dehidrasie of baie lae dehidrasie tempo's in die vloeistoffase gegee. Die vloeistof kataliste H2S04, Oksaalsuur, NaHS04 en H3P04 is ondersoek. H3P04 het uitstekende resultate gelewer. Eksperimente is op laboratoriumskaal en onder atmosferiese druk uitgevoer. Monsters is van die reaksiemengsels by verskillende tydsintervalle geneem en geanaliseer. Die sekondêre alkohol het vinnig na die ooreenstemmende alkeen gedehidreer. Die primêre alkohole het simmetriese eters teen 'n lae tempo gevorm. Die primêre en sekondêre alkohole het ook gekombineer om gemengde eters te vorm. Kort-pad-distillasie kan gebruik word om na die dehidrase reaksie die organiese produkte van die suur te verwyder. Die primêre alkohole kan verder met konvensionele distillasie gesuiwer word. Konseptueie prosesontwerpe is uitgevoer vir die skeiding en suiwering van die alkohol mengsels 1-butanol+2-pentanol en 1-pentanol+2-hexanol nadat dehidrasie van die mengsels uitgevoer is. Op laboratoriumskaal is dit gevind dat vir die skeiding van 85% 1-butanol en 15% 2-pentanol (massa %), 90 % H3P04 (massa %) met 'n suur:alkohol verhouding van 1,5:1 effektiewe dehidrase van 2-pentanol lewer. fn Reaksietyd van 70 minute word benodig. fn Konseptueie ontwerp vir die suiwering van die 1-butanol het fn produkkwaliteit van 99,5 % 1-butanol (massa %) en fn 1-butanol opbrengs van 75 % voorspel. Die 1-butanol opbrengs is laag aangesien fn groot deel van die 1-butanol verlore gaan as deel van die ternêre azeotroop wat 1-butanol met n-butieleter en water vorm. Dit is ook op laboratoriumskaal vasgestel dat vir die skeiding van 85 % 1- pentanol+15 % 2-hexanol (massa %), 90 % H3P04 (massa %) met fn suur:alkohol verhouding van 1,5:1 effektiewe dehidrase van 2-hexanollewer. fn Reaksietyd van slegs 35 minute word benodig. fn Konseptueie ontwerp vir die suiwering van die 1-pentanol het fn produkkwaliteit van 99,9 % 1-pentanol en fn 1-pentanol opbrengs van > 98 % voorspel. Die 1-pentanol opbrengs is uitstekend, en slegs die 1-pentanol wat omgeskakel word na eters gaan verlore. In hierdie studie is dit bewys dat fn dehidrasie skeidingsproses suksevol aangewend kan word om sekondêre alkohole uit fn primêre+sekondêre alkohol mengsel te verwyder. Veral die verwydering van 2-hexanol uit fn 1- pentanol+2-hexanol mengsel het belowende resultate gelewer. Om die ekonomiese lewensvatbaarheid van so fn skeidingsproses te bepaal moet fn ekonomiese evaluasie van die proses gedoen word. Dit behoort deel van verdere studies te vorm. Die dehidrasie skeidingsproses behoort verder ondersoek te word. Dit word verwag dat die proses na hoër alkohol mengsels, bv. 1-hexanol+2-heptanol uitgebrei kan word. Dit sou baie voordelig wees indien fn geskikte soliede katalis vir die skeiding gevind word. In so fn geval sou die herwinning van die organiese produkte van die reaksiemengsel baie makliker wees. Indien fn soliede katalis nie gevind word nie, behoort fn kontinu proses waarin H3P04 as vloeistof katalis gebruik word, ontwikkel te word.

In nuclear reprocessing, PUREX, a solvent extraction process, has long been the separation method employed for the separation of the bulk components of irradiated nuclear fuel (namely uranium and plutonium) from the fission products and other minor actinides produced during the fuel use. The uranium and plutonium constitutes approximately 96 % by mass of the irradiated fuel and for this to be removed, requires large volumes of extractant and equipment with large surface area contactors and therefore floor space requirements. The PUREX process has for nearly 60 years been the largely unchallenged separation technology for the reprocessing of irradiated fuel, for both nuclear weapon production and commercial nuclear power generation. The merits and ability of this process are unquestionable since it achieves the objectives of highly purified plutonium and uranium which both can be eventually recycled. Although well proven and predictable, the PUREX process is not without its challenges: the generation of significant quantities of highly active aqueous liquid containing fission products (FPs) and minor actinides (MAs), and the degradation of the solvent phase reagents and non-specific nature of the extractant TriButylPhosphate (TBP) may have contributed to only a fraction of the total annual output of irradiated fuel being reprocessed. Fission products are elements which are produced in a nuclear reactor and are the atomic fragments left after a large atomic nucleus (typically uranium-235) undergoes nuclear fission, splitting into two smaller nuclei, along with a few neutrons, the release of heat energy (kinetic energy of the nuclei), and gamma rays. Minor actinides such as neptunium, americium, curium, berkelium, californium, einsteinium, and fermium are the actinide elements in irradiated nuclear fuel other than uranium and plutonium; they are minor as they represent a very small proportion of actinides in comparison to U and Pu. This thesis explores the possibility of using a continuous chromatographic method to extract the lesser components of the irradiated fuel. One of the major problems with the use of chromatography as an industrial process is the expansion from the batch separations on the bench top to a continuous efficient process, capable of processing large volumes. This thesis, through existing concepts, will describe a proof of concept chromatographic separation of surrogates and isotopes of the components of irradiated fuels which can be readily scaled up to a continuous chromatographic separation. The project is a radical departure from PUREX and will offer many advantages over PUREX. It is based on the separation of FPs and MAs from uranium and plutonium isotopes using continuous chromatographic separation. This thesis assesses a number of commercial resins for their suitability for the proposed continuous chromatography reprocessing method. The experiments were all undertaken at elevated nitric acid concentrations and as such are describing interactions which are rarely required commercially and therefore seldom reported, with batch studies to assess separation factors between ions, uptake kinetics and isotherms over a range of nitric acid concentrations to more dynamic column breakthrough and eventually separations. The research demonstrates that a separation can be achieved at an elevated HNO3 concentration on a commercially available ion exchange resin.

Communication using speech is often an audio-visual experience. Listeners hear what is being uttered by speakers and also see the corresponding facial movements and other gestures. This thesis is an attempt to exploit this bimodal (audio-visual) nature of speech for speaker separation. In addition to the audio speech features, visual speech features are used to achieve the task of speaker separation. An analysis of the correlation between audio and visual speech features is carried out first. This correlation between audio and visual features is then used in the estimation of clean audio features from visual features using Gaussian MixtureModels (GMMs) andMaximum a Posteriori (MAP) estimation. For speaker separation three methods are proposed that use the estimated clean audio features. Firstly, the estimated clean audio features are used to construct aWiener filter to separate the mixed speech at various signal-to-noise ratios (SNRs) into target and competing speakers. TheWiener filter gains are modified in several ways in search for improvements in quality and intelligibility of the extracted speech. Secondly, the estimated clean audio features are used in developing visually-derived binary masking method for speaker separation. The estimated audio features are used to compute time-frequency binary masks that identify the regions where the target speaker dominates. These regions are retained and formthe estimate of the target speaker’s speech. Experimental results compare the visually-derived binary masks with ideal binary masks which shows a useful level of accuracy. The effectiveness of the visually-derived binary mask for speaker separation is then evaluated through estimates of speech quality and speech intelligibility and shows substantial gains over the original mixture. Thirdly, the estimated clean audio features and the visually-derivedWiener filtering are used to modify the operation of an effective audio-only method of speaker separation, namely the soft mask method, to allow visual speech information to improve the separation task. Experimental results are presented that compare the proposed audio-visual speaker separation with the audio-only method using both speech quality and intelligibility metrics. Finally, a detailed comparison is made of the proposed and existing methods of speaker separation using objective and subjective measures.

Lokal parametrische Modelle werden häufig im Kontext der nichtparametrischen Schätzung verwendet. Bei einer punktweisen Schätzung der Zielfunktion können die parametrischen Umgebungen mithilfe von Gewichten beschrieben werden, die entweder von den Designpunkten oder (zusätzlich) von den Beobachtungen abhängen. Der Vergleich von verrauschten Beobachtungen in einzelnen Punkten leidet allerdings unter einem Mangel an Robustheit. Der Propagations-Separations-Ansatz von Polzehl und Spokoiny [2006] verwendet daher einen Multiskalen-Ansatz mit iterativ aktualisierten Gewichten. Wir präsentieren hier eine theoretische Studie und numerische Resultate, die ein besseres Verständnis des Verfahrens ermöglichen. Zu diesem Zweck definieren und untersuchen wir eine neue Strategie für die Wahl des entscheidenden Parameters des Verfahrens, der Adaptationsbandweite. Insbesondere untersuchen wir ihre Variabilität in Abhängigkeit von der unbekannten Zielfunktion. Unsere Resultate rechtfertigen eine Wahl, die unabhängig von den jeweils vorliegenden Beobachtungen ist. Die neue Parameterwahl liefert für stückweise konstante und stückweise beschränkte Funktionen theoretische Beweise der Haupteigenschaften des Algorithmus. Für den Fall eines falsch spezifizierten Modells führen wir eine spezielle Stufenfunktion ein und weisen eine punktweise Fehlerschranke im Vergleich zum Schätzer des Algorithmus nach. Des Weiteren entwickeln wir eine neue Methode zur Entrauschung von diffusionsgewichteten Magnetresonanzdaten. Unser neues Verfahren (ms)POAS basiert auf einer speziellen Beschreibung der Daten, die eine zeitgleiche Glättung bezüglich der gemessenen Positionen und der Richtungen der verwendeten Diffusionsgradienten ermöglicht. Für den kombinierten Messraum schlagen wir zwei Distanzfunktionen vor, deren Eignung wir mithilfe eines differentialgeometrischen Ansatzes nachweisen. Schließlich demonstrieren wir das große Potential von (ms)POAS auf simulierten und experimentellen Daten.
In statistics, nonparametric estimation is often based on local parametric modeling. For pointwise estimation of the target function, the parametric neighborhoods can be described by weights that depend on design points or on observations. As it turned out, the comparison of noisy observations at single points suffers from a lack of robustness. The Propagation-Separation Approach by Polzehl and Spokoiny [2006] overcomes this problem by using a multiscale approach with iteratively updated weights. The method has been successfully applied to a large variety of statistical problems. Here, we present a theoretical study and numerical results, which provide a better understanding of this versatile procedure. For this purpose, we introduce and analyse a novel strategy for the choice of the crucial parameter of the algorithm, namely the adaptation bandwidth. In particular, we study its variability with respect to the unknown target function. This justifies a choice independent of the data at hand. For piecewise constant and piecewise bounded functions, this choice enables theoretical proofs of the main heuristic properties of the algorithm. Additionally, we consider the case of a misspecified model. Here, we introduce a specific step function, and we establish a pointwise error bound between this function and the corresponding estimates of the Propagation-Separation Approach. Finally, we develop a method for the denoising of diffusion-weighted magnetic resonance data, which is based on the Propagation-Separation Approach. Our new procedure, called (ms)POAS, relies on a specific description of the data, which enables simultaneous smoothing in the measured positions and with respect to the directions of the applied diffusion-weighting magnetic field gradients. We define and justify two distance functions on the combined measurement space, where we follow a differential geometric approach. We demonstrate the capability of (ms)POAS on simulated and experimental data.

Increasing operational commitments mean that military personnel are often separated from their family. Two main concerns arise: what is the impact on the serving person and family? Does increased time away from home affect retention in the Services? A review of relevant literature shows that much of the research to date has treated these as separate outcomes. Several possible research designs are considered. A pragmatist position, asserting that the research question is of primary importance in the choice of methods, is adopted. The design used is a sequential (two phase) explanatory design: quantitative followed by qualitative. A survey was conducted, with 2050 responses. Three hypotheses were tested using Analysis of Covariance. First, that separated service is associated with retention. This is supported, and a U shaped relationship is found, with both very high and low separation associated with decreased likelihood of retention. Second, some demographic groups tolerate less separation than others, before leaving. This is supported, (e.g. single personnel tolerate more separation than married). Third, increased separation from family has social impacts that in turn affect retention. This too is supported. Findings are discussed in terms of whether they fit with previous research, and whether theoretical perspectives can help to interpret the findings. A number of questions followed that are best addressed using qualitative research: How do people develop an understanding that "separation is part of the job"? And does this idea change and develop through their career? These are explored using Grounded Theory. Data collection from a total of six participants is described. Semi-structured interviews were designed to encourage interviewees to talk about experiences of separation from the point at which they joined the military, to the point at which they left. Four were interviewed in depth, with interviews transcribed. Line-by-line coding was followed by application of the constant comparison method. An initial model was drafted, and a further two interviewees were included to test fit and relevance. A Grounded Theory of separation is stated. Separated service is seen as part of the job for many military personnel. Those who state that they accept separation appear to understand what it means to be separated differently at different times, and so acceptance and understanding differ. Two core themes are: how understanding develops and changes, and what influences acceptance of separation. The data suggest a strong temporal aspect to understanding, with understanding developing alongside usual through-life changes. Acceptance of separation may be facilitated by the perception of benefits to the serving person, and may be tempered by features of the separation, and features of the serving person and family. Individuals' self-image may be affected by how they have dealt with separation in the past.

A new concept of a "fiber sorbent" has been investigated. The fiber sorbent is produced as a pseudo-monolithic material comprising polymer (cellulose acetate, CA) and zeolite (NaY) by applying hollow fiber spinning technology. Phase separation of the polymer solution provides an appropriately porous structure throughout the fiber matrix. In addition, the zeolite crystals are homogeneously dispersed in the polymer matrix with high loading. The zeolite is the main contributor to sorption capacity of the fiber sorbent. Mass transfer processes in the fiber sorbent module are analyzed for hydrogen recovery and compared with results for an equivalent size packed bed with identical diameter and length. The model indicates advantageous cases for application of fiber sorbent module over packed bed technology that allows system downsizing and energy saving by changing the outer and bore diameters to maintain or even reduce the pressure drop. The CA-NaY fiber sorbent was spun successfully with highly porous structure and high CO2 sorption capacity. The fiber sorbent enables the shell-side void space for thermal moderation to heat of adsorption, while this cannot be applied to the packed bed. The poly(vinyl alcohol) coated CA-NaY demonstrated the thermal moderation with paraffin wax, which was carefully selected and melt at slightly above operating temperature, in the shell-side in a rapidly cycled pressure swing adsorption. So this new approach is attractive for some hydrogen recovery applications as an alternative to traditional zeolite pellets.

The overall focus of this thesis is on the development and understanding of nanoporous layered silicates and membranes, particularly for potential applications in gas separations. Nanoporous layered materials are a rapidly growing area of interest, and include materials such as layered zeolites, porous layered oxides, layered aluminophosphates, and porous graphenes. They possess unique transport properties that may be advantageous for membrane and thin film applications. These materials also have very different chemistry from 3-D porous materials due to the existence of a large, chemically active, external surface area. This feature also necessitates the development of innovative strategies to process these materials into membranes and thin films with high performance.

Syftet med denna studie är att undersöka BVC:s möjligheter att förebygga de separationer som sker till följd av omställningen från att vara ett par till att även bli förälder. I studien beskrivs BHV-sjuksköterskors uppfattning om prevention av separation under småbarnsfasen samt hur BHV-sjuksköterskor ser på sina förutsättningar att arbeta med föräldrars parrelation. Studien är en kvantitativ enkätstudie. Enkäten har besvarats av BHV-sjuksköterskor anställda i Region Östergötland eller privata utförare med Region Östergötland-avtal. Totalt delades 99 enkäter ut. Svarsfrekvensen var 83 %. Resultatet visar att BHVsjuksköterskor uppfattar att det är möjligt att förebygga separation hos föräldrar i småbarnsfasen, att brister sällan framkommer i föräldrars parrelation på BVC och att många BHV-sjuksköterskor inte upplever att de har förutsättningar att arbeta med frågan. Slutsatsen är att BVC är i behov av ett förtydligat uppdrag om de ska arbeta med föräldrars parrelation liksom få rätt förutsättningar att utföra ett sådant uppdrag.
The purpose of this study is to examine the possibilities for Swedish Child Healthcare Centers to prevent parents separating as a consequence of transitioning from being a couple to having a child and becoming parents. The current study describes Child Health Care nurses’ opinions on preventing parents with small children from separating, as well as these nurses’ opinions on their possibilities to work with the parents on their relationships. The study is a quantitative questionnaire study answered by Child Health Care nurses working in public healthcare in Region Östergötland or in private facilities contracted by Region Östergötland. 99 questionnaires were handed out in total, and the answer frequency was 83 %. The results show that Child Health Care nurses feel it is possible for them to prevent parents with small children from separating, that flaws in the parents’ relationships are rarely detected at the Child Health Care Centers, and that many Child Health Care nurses don’t feel they have any possibilities to work on this issue. The conclusion is that Child Health Care Centers are in need of a clear description of their task, and whether or not this includes working with parents’ relationships; and if it does, how the centers can attain the necessary prerequisites for carrying out this task.

Aquesta tesi se centra en el desenvolupament de nous enfocaments per a processos de separació en la producció de biodièsel a partir de microalgues mitjançant tecnologia de membranes. Entre totes les etapes implicades en el procés, aquesta tesi se centra en la investigació de la deshidratació de microalgues mitjançant l'ús de diverses tècniques de filtració de membrana i en la transesterificació mitjançant l'ús d'un reactor catalític de membrana. L'etapa de collita és una de les principals responsables del cost final del biodièsel de microalgues, i la reacció de transesterificació necessita la utilització de massa quantitat d'aigua i moltes etapes que fan que aquest procés sigui inviable econòmicament per a aquesta aplicació. Calen millores en aquest sentit, a partir de la investigació de mètodes i materials més barats per al primer procés a configuracions més simples per a l'últim. Per assolir aquests objectius s'han realitzat estudis específics per a aquesta aplicació en: (i) nous materials en la filtració per membrana, a partir de polímers ja coneguts (PSF, PAN), a partir de polímers generalment no emprats en la indústria de la membrana (ABS, PETG, CA de serradures); (ii) noves tecnologies en la deshidratació de les microalgues, com un sistema de filtració vibratòria de flux transversal; (iii) noves perspectives en la reacció de transesterificació, amb la utilització de catalitzador heterogeni immobilitzat en una membrana polimèrica. Finalment, la permeabilitat és el paràmetre més estudiat en la tecnologia de filtració per membrana per a l'avaluació dels fenòmens de embrutiment. Aquest paràmetre depèn de moltes variables i el seu estudi és particularment important quan s'utilitzen membranes sintetitzades amb característiques desconegudes. Per simplificar la seva obtenció s'ha dut a terme un estudi teòric sobre la predicció de permeabilitat de la membrana amb el desenvolupament d'un model pensat per membranes poroses.
Esta tesis se centra en el desarrollo de nuevos enfoques para procesos de separación en la producción de biodiesel a partir de microalgas mediante tecnología de membranas. Entre todas las etapas implicadas en el proceso, esta tesis se centra en la investigación de la deshidratación de microalgas mediante el uso de varias técnicas de filtración de membrana y en la transesterificación mediante el uso de un reactor catalítico de membrana. La etapa de cosecha es una de las principales responsables del coste final del biodiesel de microalgas, y la reacción de transesterificación necesita la utilización de demasiada cantidad de agua y muchas etapas que hacen que este proceso sea inviable para esta aplicación. Se necesitan mejoras en este sentido, a partir de la investigación de métodos y materiales más baratos para el primer proceso a configuraciones más simples para el último. Para alcanzar estos objetivos se han realizado estudios específicos para esta aplicación en: (i) nuevos materiales en la filtración por membrana, a partir de polímeros ya conocidos (PSf, PAN) a polímeros generalmente no empleados en la industria de la membrana (ABS, PETG, CA de serrín); (ii) nuevas tecnologías en la deshidratación de las microalgas, como sistema de filtración vibratoria de flujo transversal; (iii) nuevas perspectivas en la reacción de transesterificación, con la utilización de catalizador heterogéneo inmovilizado en una membrana polimérica. Por último, la permeabilidad es el parámetro más estudiado en la tecnología de filtración por membrana para la evaluación de los fenómenos de ensuciamiento. Este parámetro depende de muchas variables y su estudio es particularmente importante cuando se utilizan membranas sintetizadas con características desconocidas. Para simplificar su obtención un estudio teórico final se ha llevado a cabo en la predicción de permeabilidad de la membrana con el desarrollo de un modelo pensado para membranas porosas.
This thesis focuses on the development of new approaches for separation processes in biodiesel production from microalgae by membrane technology. Biodiesel production from microalgae is a theme being developed in the last years that still need more investigation in order to reduce its costs. Among all steps involved in the process this thesis focuses the investigation of the microalgae dewatering by using several membrane filtration techniques and on transesterification by using a catalytic membrane reactor. Harvesting step is one of the major responsible of the final cost of microalgae biodiesel, and transesterification reaction needs the utilisation of too much quantity of water and many stages that make it unfeasible for this application. Enhancements are needed in this sense, starting from the research of cheaper methods and materials for the first process to simpler configurations for the latter one. Considerable attention has been dedicated to the complete understanding of membrane filtration technology in this application from the laboratory to the pilot plant scale. To reach these goals specific studies have been performed for this application on: (i) new materials in membrane filtration, from polymers already known (PSf, PAN) to polymers usually not employed in membrane industry (ABS, PETg, sawdust CA); (ii) new technologies in microalgae dewatering, as vibrating cross-flow filtration system; (iii) new perspectives in the transesterification reaction, with the utilization of heterogeneous catalyst immobilized on a membrane. Finally, permeability is the most studied parameter in membrane filtration technology for the evaluation of fouling phenomena. This parameter depends from many variables and its study is particularly important when synthesized membranes with unknown characteristics are used. To simplify its attainment a final theoretical study has been carried out on membrane permeability prediction by the development of a model conceived for porous membranes.

We study bounds on the distances of roots of integer polynomials and applications of such results. The separation of complex roots for reducible monic integer polynomials of fourth degree is thoroughly explained. Lemmas on roots of polynomials in the p-adic setting are proved. Explicit families of polynomials of general degree as well as families in some classes of quadratic and cubic polynomials with very good separation of roots in the same setting are exhibited. The second part of the thesis is concerned with results on p-adic versions of Mahler's and Koksma's functions wn and w*n and the related classifications of transcendental numbers in Cp. The main result is a construction of numbers such that the two functions wn and w*n differ on them for every n and later on expanding the interval of possible values for wn-w*n. The inequalities linking values of Koksma's functions for algebraically dependent numbers are proved.

With increasing environmental awareness and natural resource limitations, researchers must begin to incorporate sustainability into their process and product designs. One target for green engineering is in reaction and separation design. This is typically done in a wasteful and often toxic manner with organic solvents and lack of recycle. The following thesis discusses alternatives to these costly separations by means of ionic liquids, benign extraction, separation with carbon dioxide, and near critical water. Ionic liquids are combined with carbon dioxide to induce melting point depressions of up to 124 degrees Celsius. Using this system as a reaction medium will offer control over the reaction phases while utilizing green solvents. Benign extractions are performed on both ferulic acid and on proteins from biomass by replacing alkaline solvents and costly protein separation techniques with simple liquid-liquid extraction. This means simpler systems and less waste than from previous methods. This thesis also discusses an opportunity for more efficient separation and recycle of a pharmaceutical catalyst, Mn-Salen. Using carbon dioxide with the organic aqueous tunable solvent system, the reaction can be run homogeneously and the product and catalyst separated heterogeneously, thus creating an extremely efficient process. Lastly, near critical water is used as an extraction and reaction medium by extracting ferulic acid from Brewers Spent Grain and then catalyzing its transformation to 4-vinylguaiacol. In this manner a simple, benign process is used to turn waste into valuable chemicals. Although somewhat different, each of the studied processes strives to eliminate waste and toxicity of many commonly used reaction and separation techniques, thus creating safe and sustainable processes.

Giant vesicles may contain several spatial compartments formed by phase separation within their enclosed aqueous solution. This phenomenon might be related to molecular crowding, fractionation and protein sorting in cells. To elucidate this process we used two chemically dissimilar polymers, polyethylene glycol (PEG) and dextran, encapsulated in giant vesicles. The dynamics of the phase separation of this polymer solution enclosed in vesicles is studied by concentration quench, i.e. exposing the vesicles to hypertonic solutions. The excess membrane area, produced by dehydration, can either form tubular structures (also known as tethers) or be utilized to perform morphological changes of the vesicle, depending on the interfacial tension between the coexisting phases and those between the membrane and the two phases. Membrane tube formation is coupled to the phase separation process. Apparently, the energy released from the phase separation is utilized to overcome the energy barrier for tube formation. The tubes may be absorbed at the interface to form a 2-demensional structure. The membrane stored in the form of tubes can be retracted under small tension perturbation. Furthermore, a wetting transition, which has been reported only in a few experimental systems, was discovered in this system. By increasing the polymer concentration, the PEG-rich phase changed from complete wetting to partial wetting of the membrane. If sufficient excess membrane area is available in the vesicle where both phases wet the membrane, one of the phases will bud off from the vesicle body, which leads to the separation of the two phases. This wetting-induced budding is governed by the surface energy and modulated by the membrane tension. This was demonstrated by micropipette aspiration experiments on vesicles encapsulating two phases. The budding of one phase can significantly decrease the surface energy by decreasing the contact area between the coexisting phases. The elasticity of the membrane allows it to adjust its tension automatically to balance the pulling force exerted by the interfacial tension of the two liquid phases at the three-phase contact line. The budding of the phase enriched with one polymer may be relevant to the selective protein transportation among lumens by means of vesicle in cells.
In der wässrigen Lösung im Inneren von Riesenvesikeln können sich mehrere, räumlich getrennte Phasen ausbilden. Dieses Phänomen könnte im Zusammenhang stehen mit wichtigen Prozessen innerhalb von Zellen, wie etwa Fraktionierung und Sortieren von Proteinen, oder etwa das sog. “Molecular Crowding”. Wir studieren diesen Prozess am Beispiel von zwei unterschiedlichen Polymeren, Polyethylen Glycol (PEG) und Dextran, innerhalb von Riesenvesikeln. Die Dynamik der Phasentrennung dieser eingeschlossenen Polymerlösung lässt sich untersuchen, indem man die Vesikel einer hypertonischen Lösung aussetzt. Durch die Dehydrierung entsteht dabei überschüssige Membranfläche. Je nach Grenzflächenspannung zwischen den koexistierenden Phasen, sowie zwischen der Membran und den beiden Phasen, wird diese überschüssige Fläche entweder zur Ausbildung röhrchenartiger Strukturen verwendet, oder aber es stellen sich morphologische Veränderungen am Vesikel ein. Die Ausbildung der Membranröhrchen ist offenbar gekoppelt an den Phasentrennungsprozess: Die Energie, die bei Phasentrennung frei wird, dient offenbar dazu, die Energiebarriere der Röhrchenbildung zu überwinden. Die Röhrchen können an der Grenzfläche absorbiert werden und dort eine zweidimensionale Struktur ausbilden. Durch kleine Störungen in der Spannung kann die in Form von Röhrchen gespeicherte Membran wieder in deren Oberfläche zurückgezogen werden. Desweiteren wurde in diesem System ein Benetzungsübergang entdeckt, der bisher nur in wenigen experimentellen Systemen beobachtet werden konnte: Erhöht man die Polymerkonzentration, so geht die PEG-reiche Phase von vollständiger zu unvollständiger Benetzung der Membran über. Steht in einem Vesikel, in dem beide Phasen die Membran benetzen, ausreichend überschüssige Membranfläche zur Verfügung, so wird sich eine Phase aus dem Vesikelkörper herauswölben, was zur Trennung der beiden Phasen führt. Dieser benetzungsinduzierte Auswölbungsprozess wird durch die Oberflächenenergie bestimmt und von der Membranspannung moduliert. Dies konnte experimentell an Vesikeln gezeigt werden, die zwei Phasen beinhalten, indem durch eine Mikropipette ein Unterdruck erzeugt wurde. Die Oberflächenenergie kann durch Auswölbung einer der Phasen signifikant verringert werden, da die Kontaktfläche zwischen den koexistierenden Phasen verkleinert wird. Die Elastizität der Membran erlaubt es, die Spannung automatisch anzupassen, sodass die ziehende Kraft ausgeglichen wird, die durch die Grenzflächenspannung der beiden flüssigen Phasen an der drei-Phasen Kontaktlinie ausgeübt wird. Die Auswölbung einer durch Polymere angereicherten Phase könnte relevant sein für den selektiven Transport von Proteinen mit Vesikeln in der Zelle.

Chiral sulfoxides are most widely used in asymmetric synthesis. Their application as chiral synthons has now become a well-established and reliable strategy, mainly due to availability and high asymmetric induction exerted by the chiral sulfinyl group. Very few articles have been published on the separation of chiral sulfoxides; most involve HPLC or GC. The first separation of optically active sulfoxides was described by Phillips and co-workers. To date no work has been reported using capillary electrophoresis for the separation of alkylaryl sulfoxides. A series of alkylaryl sulfoxides were synthesized. Conditions for their separation were investigated using a modified 125 mM Boric acid (pH 8.5)/ 75 mM SDS buffer solution (MEKC buffer). Synthetic procedures for the preparation of these sulfoxides will be presented as well as separation results. The separation is based on the differential partition of solutes between the micelle and the bulk solution.