PRECIPITATION AND COACERVATION IN POLYELECTROLYTE-COLLOID SYSTEMS

Complex coacervation between oppositely charged polyelectrolytes (PEs) and colloids (i.e. micelles and proteins) has increasingly become popular due to the use of these materials in a range of applications including but not limited to personal care, biomaterials, protein purification, and food science. In taking advantage of complex coacervation, which is a liquid-liquid phase separation, precipitation has always represented a problem by introducing inhomogeneities, irreversibility and irreproducible kinetics. Therefore, understanding the dominant factors driving the formation of precipitates is important to control outcomes. In this work, we have performed comparative studies of coacervation and precipitation in model PE-colloid systems to investigate the relationship and mechanism of formation of coacervation vs precipitation. Studies of hyaluronic acid (HA), and tragacanthin (TG) - two negatively charged PEs with different structural properties - with oppositely charged proteins β-lactoglobulin (BLG), and/or a monoclonal antibody (mAb) showed that the two phases form simultaneously. However, our results suggested that coacervates do not directly turn into precipitates, but that both species are in equilibrium with free protein and PE in the bulk phase. However, precipitation and coacervation are different in that the number of proteins that bind to each polyanion to neutralize the overall charge is important in coacervation, whereas the proximity of binding, regardless of the stoichiometry, determines precipitation. Steric shielding due to bulky PE side chains can prevent close protein to PE binding which then eliminates precipitation. While the structure of the PE affects the formation of coacervation vs precipitation in model PE-protein systems, we also found that the charge density of the colloid may have an influence. To study colloid charge density effects, we chose the sodium dodecyl sulfate (SDS) and Triton-X100 (TX100) mixed micelle system, because of the ability to tune the surface charge density by varying the molar ratio of the anionic surfactant SDS. The PE-micelle system showed separate regions of coacervation and precipitation in contrast to the PE-protein system in which the two regions were coinciding. Calorimetric studies revealed a large endotherm for the formation of precipitates. This large endotherm can be overcome by the release of counterions. Coacervation is also driven by counterion expulsion, therefore there must be a difference in the nature of counterions expelled. We defined the counterions surrounding each micelle as bound or localized. Bound counterions are located close to the micelle surface whereas localized counterions are those that are attached to charged groups on the micelle surface and are responsible for precipitate formation. This is because, the expulsion localized counterions favors the ion pairing between charged groups of PDADMAC and SDS by making the interaction between the charged groups stronger thus leading to precipitation. Overall, coacervation and/or precipitation can occur in PE-colloid systems when critical conditions are suitable. The Strength of interaction is the key to yield precipitation vs. coacervation. Bulky PE side chains cause steric shielding, which weakens the interactions therefore favors coacervation. Similarly, uniform colloid charge distribution can also cause weak interactions and eliminate precipitate formation, while concentrated charge patches on protein surface favor strong PE-protein binding thus yielding precipitate formation

Historic-geographical and Typo-morphological assessment of Lefke town, North Cyprus

[EN] Morphological analysis in cities have been employed to conduct the research on the urban form and fabric of the place, that helps to determine the conservation plans or strategies of towns that reveal clues to their own history (Whithand,2001). Such analysis methods are a process that reviews the evolution and evaluation of towns throughout history. This paper focuses on, Conzen’s and Caniggia’s ideas, MRG Conzen’s historic-geographical approaches (1968) on planning level and Caniggia’s typo-morphological process (2001) on architectural level. Those methodologies help to understand the transformation procedure of different regions of city throughout the years and recovering how the city elements and urban hierarchy are interrelated. Additionally, the focus of this paper is to study the town’s morphological transformations, regarding its spatial, geographical and historical combinations. Within this context, Geographical and historical surveys done on the whole town of Lefke, in north-west Cyprus, and a detailed explanation on the typo-morphological analyses of some particular regions will be given in this article. One of the significant character that makes the town unique is its historical background which lay down with an organic urban pattern from Ottoman period. Lefke town was first formed with a medieval character, and through centuries of functional and physical transformations, has been highly influenced by British extensions, which were either prearranged modifications affected by socio- natural, economic, and political situations, or instinctive and spontaneous changes. All these historical factors, along with its geographical features, make Lefke an interesting case to be studied with an urban typo-morphological approach.Nezhadmasoum, S.; Comert, N. (2018). Historic-geographical and Typo-morphological assessment of Lefke town, North Cyprus. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 1589-1599. https://doi.org/10.4995/ISUF2017.2017.6254OCS1589159

Impact of factors at admittance predicting intensive care unit mortality in critically ill cancer patients

Background: The aim of this study is to evaluate the prognostic factors at medical ICU admittance predicting intensive care unit (ICU) mortality in cancer patients.Methods: Retrospectively data of adult patients admitted to medical ICU of a 1200-bed university hospital during January 2012-December 2013 interval were analysed. The patients were divided into three groups; patients with solid tumor, patients with hematologic malignancy and patients without cancer. The study end point was ICU mortality.Results: 512 patients were identified; 374 patients without cancer, 89 patients with solid tumor and 49 patients with hematologic malignancy. Overall mortality rate in intensive care unit was 46% (n=236). The ICU mortality rate of patients with hematologic malignancy was significantly higher than patients with solid tumors (68.6% vs 53%; p<0.001) and patients without cancer (68.6% vs 39.8%; p<0.001). Logistic regression analysis showed high APACHE II score and the requirement for invasive mechanical ventilation (odds ratio [OR], 5.52; 95% confidence interval [CI], 2.10-14.53; p<0.001) at the time of intensive care unit admittance as independent risk factors for increased mortality. In addition, the requirement of renal replacement therapy(OR, 2.34; [CI: 1.44-3.80]; p<0.002) and vasopressors(OR, 1.67; [CI: 1.10-2.54]; p<0.02)  at the time of intensive care unit admittance were detected as independent risk factors for increased mortality in cancer free group.Conclusions: In critically ill cancer patients; high APACHE II score and the requirement of invasive mechanical ventilation should be evaluated at the time of intensive care unit admittance, for these are strong predictors of increased mortality

Multiple Perforations along the Transverse Colon as a Rare Presentation of Intestinal Behcet’s Disease: A Case Report

[No abstract available

Morphological Analysis of Frontier Villages in Cyprus

[EN] Borders may be built for security reasons however; they also demarcate administrative, economic, socio-cultural, ethnic or religious divergence. Borders change the destinies of the societies at both sides because they affect the process of urban development and delimit the economic and socio-cultural interactions. Cyprus has been experiencing an interrupted continuity along the border, i.e. green line, under the rule of UN that divides north from the south. In this regard the aim of the study is to figure out how the de facto borders affect the configuration of villages upon their existing position. As a part of an ongoing research which investigates all eleven frontier villages and towns located along the border line, this paper only focuses on the morphological and syntactic comparison of four frontier villages. Within this context, initial exploration is about the village morphologies by means of Morphological Regions based on the evolutionary insights of Conzen (2004) and Whitehand (2009). Additionally, considering shifted centrality and transformed social gathering spaces, research discusses the applicability of the comparative analyses of syntactic and morphological methods in order to reveal the characteristics of the frontier villages. The preliminary findings of the research indicates that edge villages located along the green line have a controlled spatial development with dead ends and loop layouts, where the spatial configuration presents an introverted structure. On the other hand, villages divided by the green line, presents a relatively integrated spatial structure developed on both sides of the border, maintaining traditional centrality along with emphasizing forced territoriality.Edgu, E.; Zafer Comert, N.; Ozgece, N. (2018). Morphological Analysis of Frontier Villages in Cyprus. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 1255-1264. https://doi.org/10.4995/ISUF2017.2017.5128OCS1255126