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1.
Rheological study of interactions between non-ionic surfactants and polysaccharide thickeners used in textile printing
Rebeka Fijan, Sonja Šostar-Turk, Romano Lapasin, 2007, original scientific article

Abstract: The influence of four non-ionic surfactants (isododecyl and cetyl polyoxyethylene ethers) on aqueous polysaccharide solutions (sodium alginate, guar gum, and sodium carboxymethyl guar), applicable for textile printing pastes, were studied via rheological measurements. Rheology of polysaccharide-surfactant solutions in aqueous matrices is primarily governed by polymer content, which imparts marked shear-thinning and viscoelastic character to the system. Such properties are modulated in moderate but sensible way by changes in surfactant concentration or type. Above 3% surfactants addition to non-substituted guar gum solutions results in a significant impact leading to phase separation and a particular strongly associated phase is formed due to hydrogen bonds between ethylene oxy units from the surfactant and primary hydroxyl groups in guar. A satisfactory fitting of viscosity data is obtained with both the Cross equation and the Roberts-Barnes-Carew model. The experimental results of mechanical spectra can be described quite satisfactory with both the Friedrich-Braun and the generalized Maxwell models.
Keywords: textile printing, polysaccharide thickeners, rheology, non-ionic surfactant, polymer-surfactant interactions, viscoelasticity
Published: 01.06.2012; Views: 995; Downloads: 50
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High-speed rail and air passenger transport : a comparison of the operational environmental performance
Milan Janić, 2003, original scientific article

Abstract: This paper presents an overview of the environmental performance of high-speedrail (HSR) and air passenger transport (APT) in the European Union (EU). This performance embraces the direct environmental burdens/emissions such as energy consumption, air pollution, noise, landtake and land use, safety and congestion. A comparison of the marginal values of particular burdens/emissions and their costs (externalities) is carried out. The results have shown that significant mitigation of the impacts and savings of costs could be achieved by substitution of air passenger transport by high-speed rail. The substitution can be carried out through competition and complementarity of operations of both modes.
Keywords: high-speed rail, air passenger transport, interactions, environmental performance, burdens, emmisions, externalities
Published: 05.06.2012; Views: 1031; Downloads: 65
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5.
Noise-guided evolution within cyclical interactions
Matjaž Perc, Attila Szolnoki, 2007, original scientific article

Abstract: We study a stochastic predator-prey model on a square lattice, where each of the six species has two superior and two inferior partners. The invasion probabilities between species depend on the predator-prey pair and are supplemented by Gaussian noise. Conditions are identified that warrant the largest impact of noise on the evolutionary process, and the results of Monte Carlo simulations are qualitatively reproduced by a four-point cluster dynamical mean-field approximation. The observed noise-guided evolution is deeply routed in short-range spatial correlations, which is supported by simulations on other host lattice topologies. Our findings are conceptually related to the coherence resonance phenomenon in dynamical systems via the mechanism of threshold duality. We also show that the introduced concept of noise-guided evolution via the exploitation of threshold duality is not limited to predator-prey cyclical interactions, but may apply to models of evolutionary game theory as well, thus indicating its applicability in several different fields of research.
Keywords: dynamic systems, stochastic processes, cyclical interactions, evolutionary rules, flow simulations, Monte Carlo simulations
Published: 07.06.2012; Views: 1089; Downloads: 179
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6.
Interakcije zdravil z zaviralci angiotenzinske konvertaze
Marjetka Pal, Polonca Ferk, 2012, review article

Abstract: V članku predstavljamo pregled potencialno klinično pomembnih interakcij zdravil (DDIs) z zaviralci angiotenzinske konvertaze (ACE). Na osnovi pregleda dveh knjig Stockleyʼs Drug Interactions in dveh preko spleta dostopnih podatkovnih zbirk o DDIs smo opisali več kot deset takih DDIs, razložili njihove mehanizme, opredelili njihov klinični pomen ter navedli možnosti za njihovo preprečevanje oz. ustrezno obravnavo. Večina DDIs z zaviralci ACE je farmakodinamičnih, le nekaj jih je na nivoju farmakokinetike. Največ DDIs z zaviralci ACE se odraža kot prekomerno znižanje krvnega tlaka, hiperkaliemija ali nefrotoksičnost. Dokazali so tudi, da zaviralci ACE zvečajo toksičnost litija in da lahko vplivajo na pojav hudih preobčutljivostnih reakcij pri bolnikih, ki so prejeli parenteralne pripravke železa, ali pri bolnikih, ki sočasno jemljejo alopurinol. Prav tako je zaviralce ACE zaradi njihove lastne hepatotoksičnosti potrebno previdno kombinirati z drugimi hepatoksičnimi zdravili. Zaradi velike porabe zaviralcev ACE je pogostost neželenih učinkov zdravil zaradi DDIs z zaviralci ACE visoka. Ugodno pa je, da lahko v večini primerov teh DDIs ustrezno ukrepamo že s primernim kliničnim in laboratorijskim spremljanjem bolnikov oz. s prilagoditvijo odmerkov sočasno predpisanih zdravil.
Keywords: angiotensin-converting enzyme inhibitors, drug-drug interactions, drug-interaction databases
Published: 10.07.2015; Views: 780; Downloads: 21
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7.
Aquaporin-based biomimetic polymeric membranes
Joachim Habel, Michael R. Hansen, Søren Kynde, Nanna Larsen, Søren Roi Midtgaard, Grethe Vestergaard Jensen, Julie Bomholt, Anayo Ogbonna, Kristoffer Almdal, Alexander Schulz, Claus Hélix-Nielsen, 2015, review article

Abstract: In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs: aquaporin proteins (AQPs), block copolymers for AQP reconstitution, and polymer-based supporting structures. First, we briefly cover challenges and review recent developments in understanding the interplay between AQP and block copolymers. Second, we review some experimental characterization methods for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes.
Keywords: aquaporins, biomimetic membranes, block copolymers, proteopolymersomes, polyhedral oligomeric silsesquioxanes, polyamide layer, microfluidics, membrane proteins, protein-polymer-interactions
Published: 21.06.2017; Views: 423; Downloads: 27
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8.
Stability of cooperation under image scoring in group interactions
Heinrich H. Nax, Matjaž Perc, Attila Szolnoki, Dirk Helbing, 2015, original scientific article

Abstract: Image scoring sustains cooperation in the repeated two-player prisoner's dilemma through indirect reciprocity, even though defection is the uniquely dominant selfish behaviour in the one-shot game. Many real-world dilemma situations, however, firstly, take place in groups and, secondly, lack the necessary transparency to inform subjects reliably of others' individual past actions. Instead, there is revelation of information regarding groups, which allows for "group scoring" but not for image scoring. Here, we study how sensitive the positive results related to image scoring are to information based on group scoring. We combine analytic results and computer simulations to specify the conditions for the emergence of cooperation. We show that under pure group scoring, that is, under the complete absence of image-scoring information, cooperation is unsustainable. Away from this extreme case, however, the necessary degree of image scoring relative to group scoring depends on the population size and is generally very small. We thus conclude that the positive results based on image scoring apply to a much broader range of informational settings that are relevant in the real world than previously assumed.
Keywords: public goods, group interactions, phase transition, social dilemma, physics of social systems
Published: 23.06.2017; Views: 502; Downloads: 167
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9.
Vortices determine the dynamics of biodiversity in cyclical interactions with protection spillovers
Attila Szolnoki, Matjaž Perc, 2015, original scientific article

Abstract: If rock beats scissors and scissors beat paper, one might assume that rock beats paper too. But this is not the case for intransitive relationships that make up the famous rock-paper-scissors game. However, the sole presence of paper might prevent rock from beating scissors, simply because paper beats rock. This is the blueprint for the rock-paper-scissors game with protection spillovers, which has recently been introduced as a new paradigm for biodiversity in well-mixed microbial populations. Here we study the game in structured populations, demonstrating that protection spillovers give rise to spatial patterns that are impossible to observe in the classical rock-paper-scissors game.Weshow that the spatiotemporal dynamics of the system is determined by the density of stable vortices, which may ultimately transform to frozen states, to propagating waves, or to target waves with reversed propagation direction, depending further on the degree and type of randomness in the interactions among the species. If vortices are rare, the fixation to waves and complex oscillatory solutions is likelier. Moreover, annealed randomness in interactions favors the emergence of target waves, while quenched randomness favors collective synchronization. Our results demonstrate that protection spillovers may fundamentally change the dynamics of cyclic dominance in structured populations, and they outline the possibility of programming pattern formation in microbial populations.
Keywords: cyclical interactions, pattern formation, vortices, phase transitions, selforganization, biodiversity
Published: 03.07.2017; Views: 240; Downloads: 179
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10.
Emergence of target waves in paced populations of cyclically competing species
Luo-Luo Jiang, Tao Zhou, Matjaž Perc, Xin Huang, Bing-Hong Wang, 2009, original scientific article

Abstract: We investigate the emergence of target waves in a cyclic predator-prey model incorporating a periodic current of the three competing species in a small area situated at the center of a square lattice. The periodic current acts as a pacemaker, trying to impose its rhythm on the overall spatiotemporal evolution of the three species. We show that the pacemaker is able to nucleate target waves that eventually spread across the whole population, whereby three routes leading to this phenomenon can be distinguished depending on the mobility of the three species and the oscillation period of the localized current. First, target waves can emerge due to the synchronization between the periodic current and oscillations of the density of the three species on the spatial grid. The second route is similar to the first, the difference being that the synchronization sets in only intermittently. Finally, the third route toward target waves is realized when the frequency of the pacemaker is much higher than that characterizing the oscillations of the overall density of the three species. By considering the mobility and frequency of the current as variable parameters, we thus provide insights into the mechanisms of pattern formation resulting from the interplay between local and global dynamics in systems governed by cyclically competing species.
Keywords: cyclical interactions, target waves, spatial games, diversity
Published: 30.06.2017; Views: 483; Downloads: 168
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