Transport of Strontium Through a Ca-bentonite (Almer??a, Spain) and Comparison with MX-80 Na-bentonite: Experimental and Modelling

In this work, the sorption of strontium on a Ca-bentonite (CGA) from Almer??a (Spain) in column experiments was studied, and the results obtained were compared with the sorption onto the Na-bentonite (MX-80). The code CTXFIT (two site non-equilibrium sorption model) was used in order to fit the experimental data and to determine sorption and transport parameters. The effect of inlet Sr(II) initial concentration and the ionic strength were evaluated. The results obtained showed that the sorption capacities as well as the transport and sorption parameters of both bentonites were affected by the initial metal concentration. In experiments with higher inlet concentrations, columns were saturated faster, leading to shorter breakthrough and exhaustion times. On the other hand, a decrease of sorption and transport parameters was observed at higher ionic strengths, which would confirm ion exchange as the main mechanism of Sr(II) sorption onto both bentonites. The sorption parameters (sorption capacity and retardation factor) obtained indicated that the Ca-bentonite from Almer??a (Spain) presented better sorption performance than the Na-bentonite, which was related to the physical properties of the Ca-bentonite.     

Economic Optimization of Shrimp Farming in Honduras

A profit-maximizing linear programming model with a risk programming component was developed to identify sets of optimal management strategies and outline an annual schedule of production activities for shrimp farming in Honduras. A database of 912 complete pond production records was used to define technical relationships between stocking density and survival and growth rates and to develop net return coefficients for the mathematical model. Separate matrices were developed for three farm-size scenarios to account for economies of scale. Results indicated that, in spite of recent viral epizootics, shrimp farming continues to be a profitable economic activity. Stocking density was found to have a negative effect on growth rate, but not on survival rate. As a consequence, low and intermediate stocking rates were most commonly selected, but high stocking densities were recommended in certain periods of the dry season. Results demonstrated some economic advantages of reducing the traditional levels of water exchange with supplemental aeration. The risk programming analysis indicated that the selection of low and intermediate stocking rates resulted in overall annual risk levels that were relatively low.     

Vaccinia virus-induced cell motility requires F11L-mediated inhibition of RhoA signaling

RhoA signaling plays a critical role in many cellular processes, including cell migration. Here we show that the vaccinia F11L protein interacts directly with RhoA, inhibiting its signaling by blocking the interaction with its downstream effectors Rho-associated kinase (ROCK) and mDia. RNA interference-mediated depletion of F11L during infection resulted in an absence of vaccinia-induced cell motility and inhibition of viral morphogenesis. Disruption of the RhoA binding site in F11L, which resembles that of ROCK, led to an identical phenotype. Thus, inhibition of RhoA signaling is required for both vaccinia morphogenesis and virus-induced cell motility.     

Evaluation of Phenol/Aniline (Single and Binary) Removal from Aqueous Solutions onto Hyper-cross-linked Polymeric Resin (Macronet MN200) and Granular Activated Carbon in Fixed-Bed Column

This work was conducted to evaluate the sorption performance of hyper-cross-linked Macronet resin (MN200) compared to the granular activated carbon in order to remove phenol and aniline from aqueous solution in both single and binary solutions. Fixed-bed column experiments were used to obtain the breakthrough curves. The experimental data were fitted to the Thomas, Bed Depth Service Time and Yoon?CNelson models, well-established fixed-bed sorption models. The theoretical sorption capacities obtained by the Thomas model were in good agreement to the breakthrough capacities determined from the sorption data. The sorption capacity decreased in binary sorption for resin MN200, while activated carbon reported similar (aniline) or higher (phenol) sorption performance indicating a synergistic effect between both solutes on the activated carbon surface. A good prediction of the breakthrough curves in binary solution was obtained by using an approach that considers a simple model to describe a breakthrough curve (Thomas) and modified isotherm equilibrium. The resin MN200 fixed-bed columns were easily regenerated by using a methanol solution, reporting more above of 90% of recovery for both solutes, while about 50% was the recovery of activated carbon after single experiments. The regeneration after the binary sorption experiments reported a decrease in the solute recovery, effect that was especially evident for activated carbon.     

Recovery of Ammonium by Powder Synthetic Zeolites from Wastewater Effluents: Optimization of the Regeneration Step

Nitrogen recovery and valorization is gaining interest due to the current need for nitrogen removal, so it is of great interest that ammonium-selective sorbents be evaluated. In this study, a zeolitic material synthesized from coal fly ash (Ze–Na) in sodium form as well as its modification to potassium form (Ze–K) were evaluated as sorbent materials for the recovery of ammonium from wastewater effluents. The sorption performance was assessed through three consecutive sorption-desorption cycles reporting opposite behavior in terms of ammonium sorption capacity. Decreasing in the case of Ze–Na and to slightly increase for Ze–K due to alkaline activation of zeolite surface. The maximum sorption capacities obtained were 109 ± 4 mg NH₄/g and 33 ± 1 mg NH₄/g for Ze–Na and Ze–K, respectively. It is important to point out that in the case of Ze–Na, the maximum sorbent capacity was obtained during the first sorption cycle whereas in the case of Ze–K, it was obtained during the last working cycle due to the alkaline regeneration. Kinetic studies showed that after every regeneration step, the sorption kinetics turn faster as alkaline desorption increased the zeolite-specific surface, thus increasing the size of porous and enhancing the diffusion through the particle. Results obtained indicate that sorption capacity decreased significantly after every working cycle using Ze–Na whereas Ze–K followed the opposite behavior despite its initial lower sorption capacity.     

Development of biodegradable films based on blue corn flour with potential applications in food packaging. Effects of plasticizers on mechanical,thermal, and microstructural properties of flour films

In the present study, blue corn flour films were developed. The cereal grain’s total composition (excluding the pericarp) is used to obtain the films. The plasticizing effects of two different polyols such as glycerol and sorbitol on the mechanical, thermal, and microstructural properties of flour films were researched. The results showed that films plasticized with sorbitol had better mechanical properties and less affinity for water than those plasticized with glycerol. The sorbitol-plasticized films were more rigid and did not lose their integrity when immersed in water. The ATR-FTIR spectra of blue corn flour plasticizer with sorbitol showed the presence of the additional band at 1745 cm⁻¹ characteristic of the vibrational carbonyl peak, which confirms the chemical linkages between sorbitol and a polymeric matrix. The effect of the plasticizer on the glass transition temperature (T_g) was characterized using differential scanning calorimetry (DSC). T_g decreased as the plasticizer content increased. Plasticized glycerol films showed lower T_g values than those with sorbitol. SEM observations showed that it was necessary to add plasticizer to maintain film integrity. The sorbitol-plasticized flour films revealed better adhesion between phases, and these films showed a compact structure.     

An Economic Analysis of the Performance of Three Sizes of Catfish Ictalurus punctatus Fingerlings Understocked in Multiple-Batch Production

Abstract.— Different sizes of catfish fingerlings understocked in multiple-batch production may result in different survival, yield, cost, and economic risk. A pond production study was conducted to compare net yield, growth, survival, costs, and economic risk of understocking 7.6-cm, 12.7-cm. or 17.8-cm channel catfish Ictalurus punctatus fingerlings in growout ponds. Fingerlings were understocked at 15,000/ha with 1,369 kg/ha carryover fish averaging 0.58 kg. Mean growth rate increased significantly with size of fingerling understocked (1.4 ± 0.2 g/d, 1.8 ± 0.07 g/ d, and 2.2 ± 0.06 g/d for 7.6-cm, 12.7-cm, and 17.8-cm understocked fingerlings, respectively). Mean individual weights at harvest also increased significantly with size at stocking but none of the understocked fingerlings reached minimum market size (0.57 kg) over the 201-d study period. Survival of the smallest (7.6-cm) understocked fingerlings was significantly lower, but there was no difference in survival between the two other treatments. Net yields were highest for the two treatments understocked with 12.7- and 17.8-cm catfish and significantly lower for the treatment understocked with 7.6-cm fish. Growth of large carryover fish was significantly less in the treatment understocked with 17.8-cm fingerlings. Breakeven production costs were highest for the treatment understocked with 7.6-cm fish and lower for the other two treatments. The risk analysis showed that it was very likely that the 12.7- and 17.8-cm understocked fish could be grown profitably (very little risk of costs exceeding $ 1.32/kg—$1.65/kg). However, the risk of growing out 7.6-cm understocked fish at costs above market prices increased sharply. This static analysis indicated that the preferred size to understock in growout ponds would be 12.7 cm; however, additional work is needed in a dynamic framework to quantify the benefit of 17.8-cm fingerlings reaching market size earlier in the second year.     

Hepatitis B Surface Antigen S Gene is an Effective Carrier Molecule for Developing GnRH DNA Immunocastration Vaccine in Mice

Relatively molecular mass of GnRH antigens is small and hence needs to couple to a large carrier molecule to enhance its immunogenicity. This study investigated whether hepatitis B surface antigen S (HBsAg‐S) gene can be used as an effective carrier molecule for developing GnRH DNA immunocastration vaccine. Two copies of human GnRH gene were fused with HBsAg‐S gene for constructing a recombinant plasmid pVAX‐HBsAg‐S‐2GnRH that coded for 27 kDa target fusion protein. Ten male mice were divided into two equal groups, treatment and control. The vaccine (50 μg/mice) prepared in saline solution was injected into male mice at weeks 0, 1, 2, 4 and 7 of the experiment. Vaccine's efficacy was evaluated in terms of GnRH‐specific IgG antibody response, plasma testosterone levels, testicular weight and extent of the testicular tissue damage. The specific anti‐GnRH antibody titre in vaccinated animals was significantly higher than in controls in only 4th week of immunization (p < 0.05). In addition, vaccinated animals showed lower testicular weight than those of the controls (p < 0.05). Spermatogenesis in seminiferous tubules in vaccinated animals was suppressed. In conclusion, in this study, the engineered plasmid to be used as a GnRH DNA vaccine induced antibody response and suppressed spermatogenesis in mice. This suggests that HBsAg‐S gene can be an effective carrier molecule for developing GnRH DNA immunocastration vaccine when relatively molecular mass of the aimed antigens is small.