Investigative Study of Microalgal and Electrochemical Wastewater Treatment Systems and Modeling of the Wafer-Enhanced Electrodeionization Using Supervised Learning

Wastewater has a serious impact on environment and public health due to its high concentration of nutrients and toxic contaminants. Without proper treatment, excess nutrients discharged in wastewater can cause a damage to the ecosystem such as undesirable pH shifts, cyanotoxin production, and low dissolved oxygen concentrations. Main objectives of this dissertation work were to investigate i) the biofuel potential of P. cruentum when grown in swine wastewater, ii) the influence of four most commonly used ion exchange resins on the system efficiency and selectivity for the removal of sodium, calcium, and magnesium ions, and iii) the modeling of wafer-enhanced electrodeionization with data science and machine learning techniques. The growth and lipid production of the microalgae Porphyridium (P.) cruentum grown in swine wastewater (ultra-filtered and raw) were examined as compared with control media (L−1, modified f/2) at two different salt concentrations (seawater and saltwater). The cultivation of P. cruentum in the treated swine wastewater media (seawater = 5.18 ± 2.3 mgl−1day−1, saltwater = 3.32 ± 1.93 mgl−1day−1) resulted in a statistically similar biomass productivity compared to the control medium (seawater = 2.61 ± 2.47 mgl−1day−1, saltwater = 6.53 ± 0.81 mgl−1day−1) at the corresponding salt concentration. Furthermore, no major differences between the fatty acid compositions of microalgae in the treated swine wastewater medium and the control medium were observed. The performance comparison of four commonly used cation exchange resins (Amberlite IR120 Na+, Amberlite IRP 69, Dowex MAC 3 H+, and Amberlite CG 50) and their influence on the current efficiency and selectivity for the removal of cations from a highly concentrated salt stream were also reported in this work. The current efficiencies were high for all the resin types studied. Results also revealed that weak cation exchange resins favor the transport of the monovalent ion (Na+) while strong cation exchange resins either had no strong preference or preferred to transport the divalent ions (Ca2+ and Mg2+). Moreover, the strong cation exchange resins in powder form generally performed better in wafers than those in the bead form for the selective removal of divalent ions (selectivity \u3e 1). To further understand the impact of particle size, resins in the bead form were ground into a powder. After grinding the strong cation resins displayed similar behavior (more consistent current efficiency and preference for transporting divalent ions) to the strong cation resins in powder form. This indicates the importance of resin size in the performance of wafers. Through this research, the modeling of wafer-enhanced electrodeionization with high concentration multi-ion solution has been accomplished. This paper is the first study that uses data science and machine learning techniques for the modeling of wafer-enhanced electrodeionization with high concentration multi-ion solutions. With the use of data science and machine learning, the sodium, calcium, and magnesium ion concentrations were predicted with multioutput regression and neural networks multilayer perceptron (NN-MLP), and the observed effects of different resin wafers were confirmed using both multioutput and single output regression as well as leave-one-out cross validation and NN-MLP

LIPID METABOLISM IN \u3ci\u3eTrypanosoma brucei\u3c/i\u3e: MOLECULAR CHARACTERIZATION OF FATTY ACID SYNTHESIS AND UPTAKE

My doctoral studies focused on the fatty acid metabolism of the deadly protozoan parasite, Trypanosoma brucei. Fatty acid metabolism in T. brucei can be broadly divided into two pathways, synthesis and uptake. In Chapters 2-4 I describe experiments investigating the parasite\u27s fatty acid synthesis pathway. Chapter 2 contains the initial characterization of acetyl-CoA carboxylase (ACC) in T. brucei. Knockdown of TbACC by RNA interference (RNAi) reduced parasite virulence in a mouse model, suggesting that TbACC has the potential to be utilized as a drug target. Chapters 3 and 4 explore the effects of two known ACC inhibitors, the aryloxyphenoxypropionate herbicide, haloxyfop and the green tea catechin, (−)-epigallocatechin-3-gallate (EGCG) on TbACC activity and parasite growth. Both compounds inhibited TbACC enzymatic activity and parasite growth in vitro. In Chapters 5 and 6 contain research that utilizes forward and reverse-genetic techniques to study T. brucei fatty acid uptake. In Chapter 5 I begin to characterize the role of the parasite\u27s acyl-CoA synthetase genes in fatty acid uptake and growth. Further, I demonstrate that fatty acid uptake is in part a protein mediated process. Chapter 6 describes an RNAi screen for genes involved in T. brucei fatty acid uptake. Together these studies build upon our knowledge of the unique fatty acid metabolism of T. brucei, bringing us one step closer to a potential cure for this horrible disease

Antimicrobial Peptides against Listeria monocytogenes : omic approaches and potential biotechnological applications

A Listeria monocytogenes representa uma ameaça, especialmente para pessoas com sistema imunológico fraco, crianças e mulheres grávidas. A Nisina é utilizada na indústria alimentar para comparar surtos de bactérias Gram-positivas que podem pôr em risco a saúde dos consumidores. No entanto, a pesquisa de novos compostos antimicrobianos (AMPs) tornou-se fundamental para contrastar a detecção cada vez mais frequente da resistência à nisina por L. monocytogenes. Neste trabalho, Bacillus velezensis P34 produtor de fengicina um lipopeptídeos cíclicos foi estudado como possível alternativa de AMPs para uso contra L. monocytogenes. O genoma completo de B. velezensis P34 foi investigado quanto à presença de aglomerados de genes de compostos antimicrobianos. Os compostos secretados foram identificados como fengicina A e B, e em menores quantidades bacilomicina L, por meio de análise de espectrometria de massas. A análise proteômica foi realizada para estudar o "proteosurfactoma", incluindo a proteína moonlight de L. monocytogenes tratada com uma concentração subletal de nisina, detectando a inibição do processo de virulência, além da promoção do biofilme como estratégia de resistência bacteriana. Um estudo proteômico adicional permitiu pela primeira vez a reação fisiológica em L. monocytogenes tratada com os AMPs secretados por Bacillus velezensis P34. Neste estudo, uma nanoencapsulação em lipossomas foi avaliada como aplicação biotecnológica. Dentre os principais resultados deste último trabalho, foi observada forte desregulação dos transportadores de manganês com intensa regulação de outros transportadores de metais para a homeostase de íons metálicos, além de forte regulação negativa de proteínas relacionadas com os principais fatores de virulência Prfa, σB e virR. Além disso, foi realizado um estudo de comparação proteômica e lipidômica adicional, no qual os AMPs de nisina e fengicina foram considerados nesta pesquisa. A forte regulação negativa de proteínas e a variação quantitativa dos ácidos graxos do lipidoma da membrana sugeriram fortemente a inibição do biofilme quando tratado com uma concentração subletal de lipopeptídeos de fengicina; enquanto um grupo de proteínas de membrana foi investigado por sua ação na manutenção da possível resistência de membrana aos AMPs. Os resultados sugeriram a estrutura multicelular do biofilme como a principal preocupação quando pequenas quantidades de nisina podem ser utilizadas, além de que o estudo da ação de compostos secretados de Bacillus velezensis P34 sobre L. monocytogenes pode representar um importante ponto de partida para estudos mais aprofundados de fengicina para uso contra Gram-bactérias positivas, incluindo cepas multirresistentes.Listeria monocytogenes poses a threat especially to people with weak immune systems, children, and pregnant women. Nisin is employed in food industries to contrast Gram positive bacteria outbreaks, which could endanger the health of consumers. However, the research of new antimicrobial compounds (AMPs) has become pivotal to contrast the always more frequent detection of L. monocytogenes nisin resistance. In this doctoral dissertation, the Bacillus velezensis P34, producer of fengycin cyclic lipopeptides as possible alternative AMPs, to use against L. monocytogenes, was studied. Bacillus velezensis P34 whole genome was investigated because of the presence of antimicrobial compound gene clusters, and the secreted compounds were identified as fengycin A and B and, in smaller quantities, bacillomycin L through mass spectrometric analysis. Proteomics analysis was carried out to study the “proteosurfactome” including moonlight protein of L. monocytogenes treated with a sub-lethal concentration of nisin detecting the inhibition of the virulence process besides the biofilm promotion as a bacterial resistance strategy. An additional proteomic study permitted, for the first time, to detect the physiological reaction on L. monocytogenes treated with the AMPs secreted by Bacillus velezensis P34; in the latter, a biotechnological application, specifically a liposome nanoencapsulation, was evaluated. Among the main results of this latter work, strong deregulation of the manganese transporters was observed with intense regulation of others metals transporters for the metal ions homeostasis, besides a strong downregulation of proteins related with the main virulence factors Prfa, σB and virR Moreover, an additional proteomic and lipidomic comparison study was performed, nisin and fengycin AMPs were considered in the experimental drawing of this latter. The strong downregulation of proteins and, quantitatively, the variation of membrane lipidome fatty acids strongly suggested the inhibition of biofilm when treated with a sub-lethal concentration of fengycin lipopeptides; whereas a group of membrane proteins was investigated for their action on the maintaining of the possible membrane resistance to AMPs. The results suggested the promotion of biofilm multicellular organization as the main concern when sub-lethal concentration of nisin was used, besides to that the L. monocytogenes responses to the CLPs synthesized by Bacillus velezensis P34 may represent an important start for deeper studies involving the antimicrobial action of fengycin to use against Gram-positive bacteria, including multiresistant strains

Engineered zeolitic materials : synthesis and application

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2016-2017Les zéolithes étant des matériaux cristallins microporeux ont démontré leurs potentiels et leur polyvalence dans un nombre très important d'applications. Les propriétés uniques des zéolithes ont poussé les chercheurs à leur trouver constamment de nouvelles utilités pour tirer le meilleur parti de ces matériaux extraordinaires. Modifier les caractéristiques des zéolithes classiques ou les combiner en synergie avec d'autres matériaux se trouvent être deux approches viables pour trouver encore de nouvelles applications. Dans ce travail de doctorat, ces deux approches ont été utilisées séparément, premièrement avec la modification morphologique de la ZSM-12 et deuxièmement lors de la formation des matériaux de type coeur/coquille (silice mésoporeuses@silicalite-1). La ZSM-12 est une zéolithe à haute teneur en silice qui a récemment attiré beaucoup l’attention par ses performances supérieures dans les domaines de l'adsorption et de la catalyse. Afin de synthétiser la ZSM-12 avec une pureté élevée et une morphologie contrôlée, la cristallisation de la zéolithe ZSM-12 a été étudiée en détail en fonction des différents réactifs chimiques disponibles (agent directeur de structure, types de silicium et source d'aluminium) et des paramètres réactionnels (l'alcalinité, ratio entre Na, Al et eau). Les résultats présentés dans cette étude ont montré que, contrairement à l’utilisation du structurant organique TEAOH, en utilisant un autre structurant, le MTEAOH, ainsi que le Al(o-i-Pr)3, cela a permis la formation de monocristaux ZSM-12 monodisperses dans un temps plus court. L’alcalinité et la teneur en Na jouent également des rôles déterminants lors de ces synthèses. Les structures de types coeur/coquille avec une zéolithe polycristalline silicalite-1 en tant que coquille, entourant un coeur formé par une microsphère de silice mésoporeuse (tailles de particules de 1,5, 3 et 20-45 μm) ont été synthétisés soit sous forme pure ou chargée avec des espèces hôtes métalliques. Des techniques de nucléations de la zéolithe sur le noyau ont été utilisées pour faire croitre la coquille de façon fiable et arriver à former ces matériaux. C’est la qualité des produits finaux en termes de connectivité des réseaux poreux et d'intégrité de la coquille, qui permet d’obtenir une stéréosélectivité. Ceci a été étudié en faisant varier les paramètres de synthèse, par exemple, lors de prétraitements qui comprennent ; la modification de surface, la nucléation, la calcination et le nombre d’étapes secondaires de cristallisation hydrothermale. En fonction de la taille du noyau mésoporeux et des espèces hôtes incorporées, l'efficacité de la nucléation se révèle être influencée par la technique de modification de surface choisie. En effet, les microsphères de silice mésoporeuses contenant des espèces métalliques nécessitent un traitement supplémentaire de fonctionnalisation chimique sur leur surface externe avec des précurseurs tels que le (3-aminopropyl) triéthoxysilane (APTES), plutôt que d'utiliser une modification de surface avec des polymères ioniques. Nous avons également montré que, selon la taille du noyau, de deux à quatre traitements hydrothermaux rapides sont nécessaires pour envelopper totalement le noyau sans aucune agrégation et sans dissoudre le noyau. De tels matériaux avec une enveloppe de tamis moléculaire cristallin peuvent être utilisés dans une grande variété d'applications, en particulier pour de l'adsorption et de la catalyse stéréo-sélective. Ce type de matériaux a été étudié lors d'une série d'expériences sur l’adsorption sélective du glycérol provenant de biodiesel brut avec des compositions différentes et à des températures différentes. Les résultats obtenus ont été comparés à ceux utilisant des adsorbants classiques comme par exemple du gel de sphères de silice mésoporeux, des zéolithes classiques, silicalite-1, Si-BEA et ZSM-5(H+), sous forment de cristaux, ainsi que le mélange physique de ces matériaux références, à savoir un mélange silicalite-1 et le gel de silice sphères. Bien que le gel de sphères de silice mésoporeux ait montré une capacité d'adsorption de glycérol un peu plus élevée, l'étude a révélé que les adsorbants mésoporeux ont tendance à piéger une quantité importante de molécules plus volumineuses, telles que les « fatty acid methyl ester » (FAME), dans leur vaste réseau de pores. Cependant, dans l’adsorbant à porosité hiérarchisée, la fine couche de zéolite silicalite-1 microporeuse joue un rôle de membrane empêchant la diffusion des molécules de FAME dans les mésopores composant le noyau/coeur de l’adsorbant composite, tandis que le volume des mésopores du noyau permet l’adsorption du glycérol sous forme de multicouches. Finalement, cette caractéristique du matériau coeur/coquille a sensiblement amélioré les performances en termes de rendement de purification et de capacité d'adsorption, par rapport à d'autres adsorbants classiques, y compris le gel de silice mésoporeuse et les zéolithes.Zeolites as microporous crystalline materials have shown competence and versatility in a huge number of applications. Their unique properties have persuaded researchers to constantly look for novel pathways to get the most out of these extraordinary substances. Modifying the properties of classical zeolites or combining them synergistically with other materials are found to be two viable techniques to attain efficient zeolitic materials with improved characteristics. In this dissertation, these two approaches were separately used to study, first, the morphological modification of ZSM-12 and second, the formation of mesoporous silica@silicalite-1 core-shell materials. ZSM-12 is a high silica zeolite which has recently attracted much attention owing to its superior performance in adsorption and catalysis. In order to synthesize ZSM-12 with high purity and controlled size and morphology, the crystallization behavior of ZSM-12 zeolite was thoroughly studied by screening different commercially available chemical sources (structure-directing agents, silicon and aluminum source types) and compositions (alkalinity and Na, Al and water contents). The results presented in this study showed that, in contrast to TEAOH organic template, using MTEAOH and Al(o-i-Pr)3 could lead to the formation of mono-sized ZSM-12 single crystals in a shorter time. Alkalinity and Na+ contents were found to be playing the major roles. Following the second approach, zeolitic core-shell composites with a polycrystalline silicalite-1 shell, enclosing a mesoporous silica microsphere core (particle sizes of 1.5, 3 and 20-45 μm) in either pure form or loaded with metal guest species, were synthesized. Seeded growth technique was used as one of the reliable ways for the synthesis of such a material. The quality of the final products in terms of the pore network connectivity and shell integrity, which, together, ensure the shape-selective capability, was studied by varying synthesis parameters, such as core pre-treatments which include surface modification, seeding and calcination steps and the number of secondary hydrothermal crystallization steps. Depending on the core size and the presence of guest species, the quality of the seeding step was found to be influenced by the surface modification technique used, i.e., mesoporous silica microspheres which contain guest species need an additional treatment of chemical functionalization of the external surface with species such as APTES, rather than using a simple surface modification with ionic polymers. It was also shown that depending on the core size, two to four short hydrothermal treatments are required to fully cover the core, with no aggregation and core dissolution. Such materials with a molecular sieve crystalline shell can be used in a wide variety of applications, particularly for shapeselective adsorption and catalysis purposes. Selective adsorption capability of the final product was investigated by conducting a series of batch glycerol adsorption experiments from crude biodiesel with different compositions at different temperatures. Glycerol content of the purified biodiesel by using the core@shell material was compared to those purified by using conventional adsorbents including bare mesoporous silica gel spheres, classical zeolites, e.g., silicalite-1, pure siliceous β-zeolite (Si-BEA) and ZSM-5(H+) crystals as well as a physical mixture of the constitutive materials, i.e., equally mixed silicalite-1 and silica gel spheres. Although mesoporous silica gel spheres showed slightly higher glycerol adsorption capacity, the study revealed that the mesoporous adsorbents tended to trap a significant number of bulkier molecules, such as FAMEs, in their large pore networks (dpore> 6 nm). However, the silicalite-1 shell provided a microporous membrane which hindered the diffusion of FAME into the mesopores while the composite adsorbents benefited from large pore volume of mesoporous silica as core compartment, allowing a multi-layer glycerol adsorption. This feature of the synthesized core@shell material considerably enhanced the dry washing performance in terms of purification yield and adsorption capacity, in comparison to other conventional adsorbents including mesoporous silica gel and classical zeolites

Microalgae for the biochemical conversion of CO2 and production of biodiesel

As the global population rises to an estimated 9.4bn by 2050, the pressure for food, fuel and freshwater will continue to increase. Current renewable energy technologies are not widely applicable to the transport sector, which requires energy dense liquid fuels that drop into our existing infrastructure. Algal biofuels promise significantly higher yields than plants, without the displacement of valuable agricultural resources and have the potential to meet the global demand for transport fuel. Fossil fuel energy is largely ‘a legacy of algal photosynthesis’, with algae accounting for ~50% of global CO2 fixation today. In addition, these curious organisms show remarkable diversity in form, behaviour and composition. Recently there has been a global resurgence of interest in microalgae as a resource of biomass and novel products. With the present level of technology, knowledge and experience in commercial scale aquaculture, the capital cost and energy investment for algal biomass production is high. Culturing, harvesting and disrupting microalgal cells account for the largest energy inputs with more positive energy balances requiring low energy designs for culture, dewatering and extraction, efficient water and nutrient recycling with minimal waste. Little is known about the variable cell wall of microalgae, which presents a formidable barrier to the extraction of microalgal products. Staining, transmission electron microscopy (TEM) and enzymatic digestion were all utilised in an attempt to visualise, digest and characterise the cell wall of stock strains of Chlorella spp. and Pseudochoricystis ellipsoidea. The presence of algaenan, a highly resistant biopolymer, rendered staining and enzymatic digestion techniques ineffective. TEM revealed that algaenan is present in the outer walls of microalgae in a variety of conformations which appeared to impart strength to cells. A preliminary investigation utilising Fusarium oxysporum f.sp. elaeidis as a novel source of enzymes for the digestion of algaenan has also been described. Methods were developed for the mutagenesis of Chlorella emersonii and P. ellipsoidea using EMS and UV with the intent of generating cell-wall mutants. Although no viable cell wall mutants were produced, a viable pale mutant of C. emersonii was recovered 5 from UV mutagenesis. Growth rates of the pale mutant were significantly slower than the wild type, yet FAME profile was largely unaffected. Fluorescence activated cell sorting (FACS) was also investigated as a means for the rapid screening of mutagenized cells for cell wall mutants. In an attempt to reduce cooling costs of closed-culture systems, temperature tolerant species of microalgae were sought by bioprospecting the thermal waters of the Roman Baths. Numerous methods for isolation and purification of microalgae from the Baths were employed, ultimately yielding seven diverse isolates including cyanobacterial, eukaryotic, filamentous and single celled species. Despite some species possessing an increased tolerance to higher temperatures, none showed marked temperature tolerance coupled with high productivity. Further improvements to the culture conditions may have improved the productivity at higher temperatures. All seven isolates were deposited to the Culture Collection of Algae and Protozoa (CCAP). A variety of extraction methods including soxhlet, beadbeating, sonication and microwaving was investigated for efficacy of extracting fatty acid methyl esters (FAMEs) from C. emersonii. Beadbeating proved most effective in the extraction of FAMEs from C. emersonii. Microwaving showed potential as a rapid method of extraction yet was coupled with degradation of FAMEs, requiring further method development to resolve this issue. Method development has been a significant component of the work described in this thesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Influences of molecular profiles of biodiesels on atomization, combustion and emission characteristics

In this thesis, aspects of atomization, combustion and emission were investigated for a range of biodiesels. The selected fuels have different carbon chain lengths and unsaturation degrees and consequently different fuel oxygen contents (FO). Fundamental studies of secondary atomization were conducted using an air cross flow stream. Investigation of spray flames was performed using a hot co-flow burner. Fuel utilization was examined using a well-instrumented common-rail engine. Secondary atomization was characterized in terms of three fluid elements namely small drops, large objects and ligaments. It was found that at a low We number, a significant change in shape probabilities occurs when moving from a bag break-up regime to higher We numbers and some small differences in liquid shapes are found amongst the tested fuels. However, up to a certain Weber number (such as We = 200), the probability of detection of different shapes is almost independent of the breakup regimes as well as the fuel properties. Comparing performances of flame structures in the hot co-flow burner indicated that the auto-ignition characteristics (e.g. the change in chemiluminescence emission and the growth of reaction zone width) are affected by the fuel-air ratio and also by the fuel molecular structure. Engine studies confirmed that differences in biofuel molecular profiles significantly affect engine combustion and emission characteristics. The study on engine cycle variability established a link between the cyclic variability and the oxygen ratio, which is a good indicator of stoichiometry. The current research also revealed that a critical key to reducing the total particle mass, particle size, particle number, and black carbon concentration is to increase the FO. However, an increase in the FO leads to a substantial increase in the total particle number per unit of particle mass, the amount of black carbon per unit of particle mass, and the reactive oxygen species concentration

Chemical Tools for Protein Imaging in Live Bacterial Cells

Bacteria spatially and temporally localize their proteins to carry out fundamental cellular processes. Methods for visualizing protein subcellular localization have been critical to our understanding of prokaryotic cell biology. Fluorescent reporters have been instrumental for imaging bacterial proteins in live cells. Small-molecule fluorescent dyes, which have favorable spectral properties, including high brightness and photostability, are attractive in labeling proteins of interest. Here we present a method to site-specifically label the N-termini of bacterial protein targets in situ for fluorescence imaging in bacterial cells. The method uses the eukaryotic enzyme N-myristoyltransferase to ligate target proteins, bearing a nonapeptide recognition sequence, with an azide-bearing fatty acid. Subsequent strain-promoted azide–alkyne cycloaddition with fluorophores enable tagging of chemotaxis and cell division proteins in live cells. We describe using a reactive BODIPY fluorophore for visualization of the chemotaxis proteins Tar and CheA and the division proteins FtsZ and FtsA. Next we integrate a single copy of the gene encoding the protein target into the chromosome via Tn7 transposon mutagenesis and use the method to fluorescently label a bacterial chemoreceptor. Finally, we describe the preparation of photoswitchable rhodamine spirolactam dyes for super-resolution imaging in live bacterial cells. Our work highlights the utility of using photoswitchable molecules to label intracellular protein targets. The ability to tag proteins, perform super-resolution imaging, and visualize proteins in space and time will prove broadly useful

Distribution of Heavy Metals from Flue Gas in Algal Bioreactor

Algae are microscopic organisms with a great potential to produce biomass and lipids at productivities several times higher than terrestrial crops. To grow, these organisms consume carbon dioxide (CO2), a greenhouse gas. This gas, emitted primarily by power plants after coal burning, can be effectively used for algae production, thus resulting in CO2 remediation and biomass beneficial utilization as feedstuff, industrial filler and biodiesel feedstock. However, since coal is a fuel mined from the earth’s crust, it contains heavy metals that are released during coal burning and inevitably enter the algal cultivation system, contaminating the water were algae is grown, the algal biomass and the products derived from such biomass. The distribution of heavy metals from flue gas in algal cultivation systems is unknown, yet necessary to advance this industry. This study focused on quantifying the distribution and effects that ten coal-derived heavy metals (Cu, Co, Zn, Pb, As, Se, Cr, Hg, Ni and Cd) will have on algae strain Scenedesmus obliquus and on the potential products derived from this algae

Conceptualisations of Educational Technology in Distance Education: with special reference to the British Open University, the Spanish Universidad Nacional de Educacion a Distancia, and the Portuguese Universidade Aberta

This research addresses the question of what is the concept and role of educational technology in relation to distance education. This question is approached through an examination of three distance teaching universities: the British Open University (OU), the Spanish Universidad Nacional de Educación a Distancia (UNED), and the Portuguese Universidade Aberta (UA). A socio-cultural analysis explores the history, philosophical assumptions and applications of educational technology at each of the universities. Thus educational technology and distance education are discussed as interdependent and overlapping concepts. The socio-cultural approach is applied within a multi-modal systems theoretical framework. Along with these, the concept of world-view in intercultural communication is of central importance. On the basis of this theoretical scaffolding the research has sought to avoid any comparative judgements of the relative 'superiority vs. inferiority' of the various distance teaching universities that might hinder meaningful interactions among them. As a qualitative inquiry the research rejects models and attitudes of assimilation ('cultural domination' or 'sub-cultural imperialism') and seeks to show the value of dialogue between, and the recognition of diversity among, the participating institutions. Field work, including interviews and documentary analysis, has been conducted at the three major sites: Lisbon, Madrid and Milton Keynes. The interview data has been analysed using the GABEK (Ganzheitliche Bewaltigung von Komplexität - Holistic Processing of Linguistically Represented Complexity) method. The analysis not only identified a number of key issues about educational technology and distance education, from a multicultural perspective, but it also gave rise to a new definition of educational technology in terms of curriculum and power. The social function, along with the academic raison d'etre of these institutions, has been further explored and contextualised. Among the prominent topics that emerge from the various analyses is that of ethics: a relatively unexamined area in the field of distance education and educational technology. An effort has been made to introduce ethical concerns on the agenda for reflection among educational technologists and distance educational practitioners. I suggest that this topic has special relevance both to international collaborations and to the current engagement of the three universities in question with the promotion of distance education in developing countries. Finally, a proposal for the building up of communities of discourse in distance education in the various languages of this research is discussed