Short-Term Immune Responses of Gilthead Seabream (Sparus aurata) Juveniles against Photobacterium damselae subsp. piscicida

Photobacteriosis is a septicaemic bacterial disease affecting several marine species around the globe, resulting in significant economic losses. Although many studies have been performed related to the pathogen virulence and resistance factors, information regarding the host defence mechanisms activated once an infection takes place is still scarce. The present study was designed to understand innate immune responses of farmed juvenile gilthead seabream (Sparus aurata) after Photobacterium damselae subsp. piscicida (Phdp) infection. Therefore, two groups of seabream juveniles were intraperitoneally injected with 100 µL of PBS (placebo) or 100 µL of exponentially growing Phdp (1 × 10⁶ CFU/mL; infected). The blood, plasma, liver, and head kidney of six fish from each treatment were sampled immediately before infection and 3, 6, 9, 24 and 48 h after infection for the broad screening of fish immune and oxidative stress responses. Infected animals presented marked anaemia, neutrophilia and monocytosis, conditions that are correlated with an increased expression of genes related to inflammation and phagocytic activity. Similar studies with different fish species and bacteria can be useful for the definition of health biomarkers that might help fish farmers to prevent the occurrence of such diseases.     

Structural characterization of reactor blends of polypropylene and ethylene‐propylene rubber

Blends of isotactic polypropylene (PP), ethylene‐propylene rubber copolymer (EPR), and ethylene‐propylene crystalline copolymer (EPC) can be produced through in situ polymerization processes directly in the reactor and blends with different structure and composition can be obtained. In this work we studied the structure of five reactor‐made blends of PP, EPR, and EPC produced by a Ziegler‐Natta catalyst system. The composition of EPR was related to the ratio between ethylene and propylene used in the copolymerization step. The ethylene content in the EPR was in the range of 50–70 mol %. The crystallization behavior of PP and EPC in the blends was influenced by the presence of the rubber, and some specific interactions between the components could be established. By preparative temperature rising elution fractionation (P‐TREF) analysis, the isolation and characterization of crystalline EPC fractions were made. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2155–2162, 2004     

Rheological aspects of microbial hyaluronic acid

The rheological properties of the hyaluronic acid (HA) produced by the cultivation of Streptococcus zooepidemicus ATCC 39920 in synthetic medium at constant pH of 7.0 were determined. Relevant characteristics of the biopolymer as its pureness related to proteins (0.44 mg of protein per gram of HA) and its average molar weight (4.0 × 10⁶ Da) were also determined. Experimental data in steady shear (flow curves) have been correlated with the Cross model, which described the apparent viscosity shear rate data well mainly at concentrations higher than 50 mg mL^?1.The concentration dependence of specific viscosity showed two linear regimes that intercept at critical overlap concentration (c*) equal to 4 mg mL^?1. The storage (G′) and loss (G″) moduli increasing along the HA concentration and estimates out of the studied range indicate that a crossover frequency decreased with the increasing concentration of HA. The high concentration dependence of G′ as well as the deviations of the Cox‐Merz rule for most of the HA concentrations indicate the hyperentangled properties for the HA chains, which could be visualized through atomic force microscopy images even at low concentrations as 0.01 mg mL^?1. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Analysis of solution polybutadiene polymerizations performed with a neodymium catalyst

This article is regarding the polymerization of 1,3‐butadiene with a neodymium catalyst activated by diisobutylaluminum‐hydride and diethylaluminum chloride (DEAC). The effects of the polymerization conditions (ratio between DEAC and neodymium molar concentrations, polymerization temperature, catalyst concentration, and butadiene concentration) on the polymer yield and molecular weight distribution (MWD) of polybutadiene (PB) samples were evaluated. It is shown that the DEAC/Nd ratio and the polymerization temperature are the reaction variables that influence the MWD and the catalyst performance most significantly. PBs with broad and sometimes bimodal MWD were produced at the analyzed reaction conditions. For this reason, the MWD of the obtained polymer materials was deconvoluted with the help of the Flory most probable distribution, indicating that three or more catalyst sites are required to explain the final MWD of the polymer samples. Finally, it was observed that the analyzed neodymium catalyst is able to produce branched PBs at mild reaction conditions and that the branching frequency depends on the polymerization conditions, which may be useful for development of operation policies at plant site and production of materials with improved performances. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Synthesis and characterization of polyurethane foam matrices for the support of granular adsorbent materials

Polyurethane foams with different formulations were synthesized and characterized for use as supporting matrices of granular solid adsorbents. The open cell content, specific gravity, thermal stability, and hydrophobicity were determined and related to the formulation composition. The synthesized foams had open cell contents of 88.1–98.5% and specific gravity values of 120–28 kg m^?3. The thermal stability of the prepared foams was influenced mainly by the water content and the type of isocyanate used. The hydrophobicity was assessed by an analysis of the water adsorption isotherms determined on selected foams, and a correlation between these results and the formulation of the foams was attempted. Two types of activated carbons were supported in a polyurethane matrix. The adsorption characteristics evaluated before and after the supporting procedure, by nitrogen adsorption, revealed that there was only a moderate surface area reduction of 15–20%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2045–2053, 2004     

Integrated ultrafiltration-nanofiltration membrane processes applied to the treatment of gold mining effluent: Influence of feed pH and temperature

This study aimed to evaluate the effect of feed pH (2.2 - original effluent pH – up to 6.0) and temperature (20 up to 40°C) on the performance of integrated ultrafiltration (UF) and nanofiltration (NF) applied to gold mining effluent. pH increase led to a significant decrease in UF permeate flux. NF showed high retention efficiencies of ions when temperature was below 30°C. Retention of high-valence counter-ions to balance the charge of retained co-ions seemed to be the strongest NF mechanisms. Process performance at feed pH of 5.0 was superior in terms of fouling, retention efficiency, and investment cost.     

Influence of particle size and fluid fraction on rheological and extrusion properties of crosslinked hyaluronic acid hydrogel dispersions

Crosslinked hyaluronic acid (HA) hydrogels are widely used in gel/HA fluid formulations as a viscosupplement to treat joint diseases; thus, it is important to characterize these hydrogels in terms of their particle size and to investigate the effects of the gel/fluid mixtures on their rheological properties and extrusion force. Hydrogels previously crosslinked with divinyl sulfone were sheared in an Ultra‐Turrax unit to produce particles with mean diameters ranging from 20 to 200 μm. Hydrogels with 75–100 μm mean diameters were also evaluated in dispersions containing a 20–40% mass fraction of HA fluid. The mean diameters were measured by laser light scattering and the rheological behavior was determined by oscillatory and steady measurements in parallel plate geometry. The HA hydrogels exhibited the typical behavior of so‐called weak gels, as analyzed by the storage and loss moduli G′ and G″, respectively. The viscoelasticity, the viscosity, and the extrusion force increased with the hydrogel particle size. The fluid phase dispersions decreased both moduli. At 40% fluid fraction, the gel characteristics were lost and the dispersion behaved as a fluid. Based on these results, the particle size and HA fluid fraction in hydrogel dispersions may be optimized to develop more efficient viscosupplement formulations. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Genetic Background and Diet Impact Beef Fatty Acid Composition and Stearoyl-CoA Desaturase mRNA Expression

The intramuscular fat composition of ruminant meats influences the quality of the final product, which explains the increasing interest in assessing the fatty acid profile of meat from different production systems. In this study, it was hypothesized that there are breed- and diet-induced variations on lipid metabolism in the muscle, which may be, at least partially, modulated by the stearoyl-CoA desaturase (SCD) gene expression levels. Forty purebred young bulls from two phylogenetically distant autochthonous cattle breeds, Alentejana and Barrosã (n = 20 for each breed), were assigned to two different diets (low vs. high silage) and slaughtered at 18 months of age. Meat fatty acid composition, including the detailed conjugated linoleic acid (CLA) isomeric profile, was determined along with the SCD mRNA levels. Meat from Barrosã bulls fed the low silage diet was richer in monounsaturated fatty acids, CLA and trans fatty acids, when compared to that from Alentejana bulls. The meat content in polyunsaturated fatty acids was similar across experimental groups. Moderate positive correlations between the SCD mRNA levels and the products of this enzyme activity were found, although they were not reflected on the calculated desaturase indices. Overall, these findings highlight the importance of taking into account the genetic background while devising feeding strategies to manipulate beef fatty acid composition.