Nonuniversal route to universality: Critical phenomena in colloidal dispersions

We investigate critical phenomena in colloids by means of the renormalization-group based hierarchical reference theory of fluids (HRT). We focus on three experimentally relevant model systems: namely, the Asakura-Oosawa model of a colloidal dispersion under the influence of polymer-induced attractive depletion forces; fluids with competing short-range attractive and longer-range repulsive interactions; solutions of star-polymers whose pair potential presents both an attractive well and an ultrasoft repulsion at shorter distance. Our results show that the ability to tune the effective interactions between colloidal particles allows one to generate a variety of crossovers to the asymptotic critical behavior, which are not observed in atomic fluids.Comment: 4 pages, 3 figure

Critical behavior in colloid-polymer mixtures: theory and simulation

We extensively investigated the critical behavior of mixtures of colloids and polymers via the two-component Asakura-Oosawa model and its reduction to a one-component colloidal fluid using accurate theoretical and simulation techniques. In particular the theoretical approach, hierarchical reference theory [Adv. Phys. 44, 211 (1995)], incorporates realistically the effects of long-range fluctuations on phase separation giving exponents which differ strongly from their mean-field values, and are in good agreement with those of the three-dimensional Ising model. Computer simulations combined with finite-size scaling analysis confirm the Ising universality and the accuracy of the theory, although some discrepancy in the location of the critical point between one-component and full-mixture description remains. To assess the limit of the pair-interaction description, we compare one-component and two-component results.Comment: 15 pages, 10 figures. Submitted to Phys. Rev.

Star polymers: A study of the structural arrest in presence of attractive interactions

Simulations and Mode-Coupling Theory calculations, for a large range of the arm number $f$ and packing fraction $\eta$ have shown that the structural arrest and the dynamics of star polymers in a good solvent are extremely rich: the systems show a reentrant melting of the disordered glass nested between two stable fluid phases that strongly resemble the equilibrium phase diagram. Starting from a simple model potential we investigate the effect of the interplay between attractive interactions of different range and ultrasoft core repulsion, on the dynamics and on the occurrence of the ideal glass transition line. In the two cases considered so far, we observed some significant differences with respect to the purely repulsive pair interaction. We also discuss the interplay between equilibrium and non equilibrium phase behavior. The accuracy of the theoretical tools we utilized in our investigation has been checked by comparing the results with molecular dynamics simulations.Comment: 24 pages, 14 figures, accepted for publication in Physical Review

Effects of plant polyphenols and mannan-oligosaccharides on growth performance, antioxidant defense system and inflammatory responses of ileal mucosa in Escherichia coli Challenged piglets

The objective of the current study was to evaluate the possible protective effects of nutritional supplements (plant polyphenols (PP) mixture containing anthocyanin, catechins, chlorgenic and oleuropein as active ingredients, mannan oligosaccharide (MOS) and PP+MOS) on growth performance, systemic antioxidant capacity and gut health in piglets under Escherichia coli challenged condition. Ninety six weanling piglets (Stambo HBI Dalland 40) (22-d-old) were homogenously allocated to 24 pens and fed a basal diet for one week. After the adaptation period, piglets were divided into 4 treatments (6 replicates with 4 piglets per treatment) and fed a basal diet or the basal diet supplemented with 0.1% of PP, MOS or PP+MOS for 6 weeks. At 21 and 25 d, half of the piglets in each treatment were orally inoculated with 4 ml of E.coli (1 7109cfu/ml) or same amount of saline water. Plasma samples collected at 7, 21, 25, 27 and 34 d and ileac mucosa samples prepared at 25 and 27 d were determined for antioxidative property and intestinal inflammatory responsive parameters. Dietary PP+MOS worsened the feed efficiency throughout the experiment. Compared to PP+MOS treatment, control group had better feed conversion ratio (FCR) during first two weeks, dietary MOS improved feed efficiency during 7 - 14 d, 0 - 34 d and 0 - 42 d, and dietary PP decreased FCR throughout the trial. Supplementation of PP markedly enhanced the systemic antioxidant property with higher total antioxidant capacity and lower malondialchehyche content compared to control or PP+MOS treatment at 21 d. At 4 d post infection (DPI), challenge didn\u2019t affect antioxidant capacity, dietary PP or MOS increased plasma GSH-Px activity. Increased plasma Malondialdehyde content, decreased plasma total antioxidant capacity (TAOC) and catalase (CAT) activity were observed at 6 DPI. Reduced TAOC were seen in challenged piglets, dietary PP or MOS increased TAOC compared to PP+MOS diet, dietary PP or PP+MOS increased CAT activity than basal or MOS diet at 13 DPI. Challenged increased plasma ceruloplasmin at 4 and 6 DPI, dietary PP or PP+MOS decreased ceruloplasmin compared to basal diet at 6 DPI. Increased ileac activities of inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) as well as nitric oxide (NO) production were observed in challenged piglets at 4 and 6 DPI. At 6 DPI, Dietary PP significantly inhibited the elevation of MPO activity and iNOS activity as well as NO production due to challenge. The overall results demonstrated that nutritional supplementation PP improved growth performance and dietary PP or MOS improved feed efficiency in presence of E.coli challenge. Dietary PP or MOS had the potential to improve the antioxidant property, and dietary PP favorably modulated gut mucosa inflammatory response induced by E.coli infection. Dietary combination of PP and MOS did not show effects and even was adverse to growth performance probably due to some unclear interactions between PP and MOS that warranted further research

Administration of a novel plant extract product via drinking water to post-weaning piglets : effects on performance and gut health

The present study evaluated the effects of a novel plant extract (PE) product (GrazixTM) on the performance and gut health of weaned piglets challenged with Escherichia coli. The PE was a standardised mixture of green tea leaves (Camellia sinensis) and pomegranate fruit (Punica granatum) obtained by using the LiveXtractTM process. A total of 144 piglets were weaned at 24 days and allocated to 8 for a 35-day experiment with a 2 7 2 7 2 factorial design comparing different treatments (water without product (CT) or 8 \u3bcl/kg per day PE in drinking water (PE)), feeding regimens (ad libitum (AD) or restricted (RE)) and oral E. coli challenges on day 9 (sham ( 12 ) or infected ( +)). There were six pens per group with three piglets per pen. On day 35, 24 of the RE feeding piglets were slaughtered. It was found that PE supplementation increased the average daily gain (ADG) from day 28 to day 35 ( P =0.03) and increased the gain to feed ratio (G : F) from day 7 to day 14 ( P = 0.02). RE feeding led to lower feed intake in piglets during the 1st week ( P<0.01), 2nd week ( P = 0.06), 3rd week ( P = 0.05), and throughout the course of the overall study period ( P = 0.05). E. coli challenge decreased the ADG and G : F ratio from day 7 to day 14 ( P = 0.08 and <0.01, respectively) and increased the faecal score (higher values indicate more severe diarrhoea) on days 14, 21, 28 and 35 ( P<0.01). PE supplementation decreased the faecal score in the challenged piglets during the 1st week post-challenge ( P<0.01). E. coli challenge increased the faecal E. coli level on day 14 ( P = 0.03) and increased the Enterobacteriaceae level on day 35 ( P<0.01). Reduced faecal E. coli was observed on days 14 and 35 ( P = 0.05 and 0.02, respectively), and reduced Enterobacteriaceae ( P<0.01) was found on day 35 in the PE animals. RE feeding increased the faecal Lactobacillus, Enterobacteriaceae and E. coli levels on day 35 ( P = 0.02, <0.01 and <0.01, respectively). These results suggest that PE supplementation may improve the gut health status of post-weaning piglets and counteract some of the negative effects that occur when piglets are challenged with E. coli

A survey on daylighting education in italian universities. Knowledge of standards, metrics and simulation tools

Daylighting is a strategic topic to achieve sustainable buildings, so it is more and more imperative that it is implemented in architecture curricula to prepare a new generation of daylighting-oriented practitioners. In this frame, the DAYKE project (Daylight Knowledge in Europe) was set up to explore the level of knowledge about daylighting among European professionals and students. DAYKE-Europe was replicated as DAYKE-Italy to study the knowledge of daylight standards, metrics and software among Italian architecture students, and to compare it to that observed within DAYKE-Europe. A sample of 542 questionnaires were collected in five universities. Primary outcomes were: (i) a general low level of knowledge on daylighting was observed; the most cited metrics were the average daylight factor and the geometrical window-to-floor ratio, while climate-based daylight metrics were rarely mentioned; (ii) master science M.Sc. students reported more knowledge on daylight metrics and regulations than bachelor B.Sc. students, while the implementation of daylight metrics and strategies in projects was mainly deficient among B.Sc. students; (iii) compared to European students (DAYKE-Europe), Italian students showed a higher knowledge of daylight metrics and software (especially as for M.Sc. students), while the opposite was observed for standards, regulations and protocols. Based on the results, a reconsideration of daylight education in architecture curricula is recommended

Fluid-fluid demixing transitions in colloid--polyelectrolyte star mixtures

We derive effective interaction potentials between hard, spherical colloidal particles and star-branched polyelectrolytes of various functionalities and smaller size than the colloids. The effective interactions are based on a Derjaguin-like approximation, which is based on previously derived potentials acting between polyelectrolyte stars and planar walls. On the basis of these interactions we subsequently calculate the demixing binodals of the binary colloid--polyelectrolyte star mixture, employing standard tools from liquid-state theory. We find that the mixture is indeed unstable at moderately high overall concentrations. The system becomes more unstable with respect to demixing as the star functionality and the size ratio grow.Comment: 24 pages, 9 figures, submitted to Journal of Physics: Condensed Matte

A Survey on Daylighting Education in Italian Universities : Knowledge of Standards, Metrics and Simulation Tools

Daylighting is a strategic topic to achieve sustainable buildings, so it is more and more imperative that it is implemented in architecture curricula to prepare a new generation of daylighting-oriented practitioners. In this frame, the DAYKE project (Daylight Knowledge in Europe) was set up to explore the level of knowledge about daylighting among European professionals and students. DAYKE-Europe was replicated as DAYKE-Italy to study the knowledge of daylight standards, metrics and software among Italian architecture students, and to compare it to that observed within DAYKE-Europe. A sample of 542 questionnaires were collected in five universities. Primary outcomes were: (i) a general low level of knowledge on daylighting was observed; the most cited metrics were the average daylight factor and the geometrical window-to-floor ratio, while climate-based daylight metrics were rarely mentioned; (ii) master science M.Sc. students reported more knowledge on daylight metrics and regulations than bachelor B.Sc. students, while the implementation of daylight metrics and strategies in projects was mainly deficient among B.Sc. students; (iii) compared to European students (DAYKE-Europe), Italian students showed a higher knowledge of daylight metrics and software (especially as for M.Sc. students), while the opposite was observed for standards, regulations and protocols. Based on the results, a reconsideration of daylight education in architecture curricula is recommended