Freshwater sponges (Porifera, Demospongiae) indicators of some coastal habitats in South America: redescriptions and key to identification

Surveys for freshwater sponges were performed at several water bodies at sandy environments along a north-south direction of particularly the Brazilian coastal line. The results allowed for the distinction of four different species-specific environments along this coastal border. The main fact considered was the dominant or the sole recurrent occurrence of a single sponge species at one particular habitat. The first one is that of the lagoonal mesohaline habitats at the tropical and subtropical realms, indicated by Spongilla alba Carter, 1849. The second one refers to shallow ponds among dunes at the tropical area indicated by Corvoheteromeyenia heterosclera (Ezcurra de Drago, 1974). The third one is that of also shallow ponds close to the dune belt at the temperate region indicated by Racekiela sheilae (Volkmer-Ribeiro, De Rosa-Barbosa & Tavares, 1988). The fourth one is that of organically enriched environments, at the marginal areas of lagoons and mouth of small rivers, evolving towards freshwater muddy ponds and coastal swamps, not far from the ocean border: Ephydatia facunda Weltner, 1895 is the species to occupy this habitat with almost exclusiveness. The above species are thus proposed as indicators of such habitats and have their descriptions improved and that of their environments summarized. A taxonomic key based on the spicules of the four species is proposed. The results presented aim to contribute to the identification of spicules of these sponges in sediment columns recovered at the Brazilian and South American coastal area. Determination of paleo ocean borders are a present issue of upmost importance in what respects projections of timing and fluctuations of ascending/regressing sea levels.

Freshwater sponges (Porifera, Demospongiae) in a benthic filter feeding community at the Guanacaste Dry Forest, Costa Rica

The freshwater sponges Trochospongilla variabilis Bonetto & Ezcurra de Drago (1973), Radiospongilla crateriformis (Potts, 1882), Spongilla cenota Penney & Racek (1968) and Corvoheteromeyenia heterosclera (Ezcurra de Drago, 1974) compose with the sphaerid bivalve Eupera cubensis (Prime, 1865) and several Phylactolaemata bryozoans a benthic filter feeding community living in seasonal lentic and lotic habitats with high Particulate Organic Carbon (POC), low conductivity and acid pH within the Costa Rica Dry Forest biome. The sponge specimens gathered led to the re-description of the four species.

Species of Oukuriella Epler (Diptera, Chironomidae) inside freshwater sponges in Brazil

Larvae of Oukuriella Epler, 1986 (Diptera, Chironomidae) inside freshwater sponges are reported for the first time in Brazil.

Ammonia volatilization and yield components after application of polymer-coated urea to maize

A form of increasing the efficiency of N fertilizer is by coating urea with polymers to reduce ammonia volatilization. The aim of this study was to evaluate the effect of polymer-coated urea on the control of ammonia volatilization, yield and nutritional characteristics of maize. The experiment was carried out during one maize growing cycle in 2009/10 on a Geric Ferralsol, inUberlândia, MG, Brazil. Nitrogen fertilizers were applied as topdressing on the soil surface in the following urea treatments: polymer-coated urea at rates of 45, 67.5 and 90 kg ha-1 N and one control treatment (no N), in randomized blocks with four replications. Nitrogen application had a favorable effect on N concentrations in leaves and grains, Soil Plant Analysis Development (SPAD) chlorophyll meter readings and on grain yield, where as coated urea had no effect on the volatilization rates, SPAD readings and N leaf and grain concentration, nor on grain yield in comparison to conventional fertilization.

In situ synthesis of nanoclay filled polyethylene using polymer supported metallocene catalyst system

In situ ethylene polymerizations were performed using bis(cyclopentadiene)titanium dichloride supported on polyethersulfone as catalyst. The bis(cyclopentadiene)titanium dichloride supported on polyethersulfone catalyst activity estimated by ethylene polymerization was 360 kgPE/molTi/h. During polymerization the fillers used were montmorillionite nanoclays having surface modifications with 35-45 wt% dimethyl dialkyl(14-18)amine (FA) and 25-30 wt% trimethyl stearyl ammonium (FB). These fillers were pretreated with methylaluminoxine (MAO; cocatalyst) for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nanofiller did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nanoclay FB filled polyethylene has higher thermal stability than nanoclay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 ºC, which corresponds to that synthesized by the polyether sulfone supported catalyst.

Water absorbent polymer in sugarcane crop

The water absorbent polymer effect on vegetative growth and production of Theoretical Recovery Sugar (TRS) of sugarcane cv. RB 86 7515 was evaluated on two field tests installed in randomized blocks, with four treatments and five repetitions. The polymer doses were 0; 4; 8 and 12 g m-1 of furrow (test 1) and 0; 1.4; 2.8 and 4.2 g m-1 of furrow (test 2). Test 1 (dec/2007 to may/2009) was implanted in a Distroferric Red Argisol soil in Presidente Prudente - State of São Paulo (SP), Brazil; and the test 2 (Aug/2008 to Aug/2009) was implanted in a Red Yellow Argisol soil in Lucélia - State of São Paulo (SP), Brazil. In test 2, there were no significant differences for any evaluated parameters. In both tests the polymer doses equal to or less than 4 g m-1 of furrow showed no significant effect on the evaluated parameters. In test 1, the polymer doses of 8 and 12 g m-1 of the conditioning polymer increased the number of tillers in stage II of development and led to the largest amount of straw. The gross income per hectare has positive relation with the polymer doses. The polymer had no significant effect on the sugarcane stems productivity and technological parameters.

Effect of particle morphology on the mechanical and thermo-mechanical behavior of polymer composites

Fiber reinforced polymer composites have been used in many applications, such as in automobile, aerospace and naval industries, due basically to their high strength-to-weight and modulus-to-weight, among other properties. Even though particles are usually not able to lead to the level of reinforcement of fibers, particle reinforced polymer composites have been proposed for many new applications due to their low cost, easy fabrication and isotropic properties. In this work, polymer composites were prepared by incorporating glass particles of different morphologies on poly(aryl sulfones) matrices. Particles with aspect ratios equal to 1, 2.5 and 10 were used. The prepared composites were characterized using electron microscopy and thermal analysis. Mechanical properties of the composites were evaluated using a four-point bending test. The thermo-mechanical behavior of the obtained composites was also investigated. The results showed that the morphology of the particles alter significantly the mechanical properties of composites. Particles with larger values of aspect ratio led to large elastic modulus but low levels of strain at failure. This result was explained by modeling the thermo-mechanical behavior of the composites using a viscoelastic model. Parameters of the model, obtained from a Cole-Cole type of plot, demonstrated that interactions at the polymer-reinforcing agent interface were higher for composites with large aspect ratio particles. Higher levels of interactions at interfaces can lead to higher degrees of stress transfer and, consequently, to composites with large elastic modulus, as experimentally observed.

Immunization by subcutaneous implants of polyester-polyurethane sponges coupled with antigen

A new protocol is described for immunization of outbred Swiss mice. The procedure is based on subcutaneous implantation of antigen-coupled polyester-polyurethane sponges cut into disks of 10 mm in diameter vs 2 mm in thickness. Antigen coupling was performed by overnight incubation of the sponge with a solution of ovalbumin (Ova) (2 mg/ml) diluted in sodium carbonate buffer, pH 9.6. The amount of ovalbumin that was taken up by the sponge was between 71.4 to 82.5 µg. This was estimated by comparing the Ova absorbance at 280 nm in coating buffer solutions before and after incubation. To compare the efficiency of the proposed method, experimental groups immunized with the antigen in the presence of adjuvants (10 µg in Al(OH)3 or 100 µg in complete Freund's adjuvant (CFA)) were run in parallel. The data obtained after the 3rd week of immunization indicate that both cellular and humoral immune responses were achieved. These were assayed by antigen-induced footpad swelling and ELISA (specific antibodies), respectively. The levels of both immune responses elicited were similar to the responses observed in mice immunized with ovalbumin in the presence of Al(OH)3. The method might represent an advantage when immunizing with pathogenic antigens. Preliminary experiments have suggested that the antigen remains immobilized or bound to the sponge for a long period of time, since there is an increment on the cell population inside the sponges after boosting the animals. If so, the undesirable effects of immunization would be reduced.

Differences in pressure and temperature transitions of proteins and polymer gels

Pressure-driven and temperature-driven transitions of two thermoresponsive polymers, poly(N-isopropylacrylamide) (pNIPAM) and poly(N-vinylisobutyramide) (pNVIBA)), in both a soluble linear polymer form and a cross-linked hydro-gel form, were examined by a dynamic light-scattering method and direct microscopic observation, respectively. Their behavior was compared with that of protein systems. Changes in some characteristic parameters in the time-intensity correlation functions of dynamic light-scattering measurement of aqueous solutions of pNIPAM at various pressures and temperatures showed no essential differences during temperature and pressure scanning and, as a whole, the motions of polymers in aqueous solutions were similar in two types of transitions until chain shrinkage occurred. The gels (cross-linked polymer gels) prepared from the thermoresponsive polymers also showed similar volume transitions responding to the pressure and temperature increase. In temperature transitions, however, gels showed drastic volume shrinkage with loss of transparency, while pressure-induced transition showed a slow recovery of transparency while keeping the size, after first transient drastic volume shrinkage with loss of transparency. At a temperature slightly higher than the transition under atmospheric temperature, so-called reentry of the volume change and recovery of the transparency were observed during the pressure-increasing process, which implies much smaller aggregation or non-aggregated collapsed polymer chains in the gel at higher pressures, indicating a certain mechanistic difference of the dehydration processes induced by temperature and pressure.