Alginate/cashew gum floating bead as a matrix for larvicide release

A polymeric floating system composed of Alginate (ALG) and Cashew gum (CG), loaded with an essential oil (Lippia sidoides–Ls) was prepared by ionotropic gelation, characterized regarding its physical-chemistry properties and evaluated on its potential as a controlled release system. The influence of process parameters on the buoyancy, loading, swelling and in vitro and in vivo release kinetics, was investigated. Results showed that beads produced with carbonate and Ls at high level contents exhibit good floatability (up to 5 days) and loading capacity (15.2–23.8%). In vitro release data showed a Fickian diffusion profile and in vivo experiments showed that ALG–CG floating system presented a superior and prolonged larvicide effect, in comparison with non-floating ones, presenting larvae mortality values of 85% and 33%, respectively, after 48 h. These results indicate that ALG–CG floating beads loaded with Ls presented enhanced oil entrapment efficiency, excellent floating ability, and suitable larvicide release pattern.     

Contribution to the modeling of the interaction between a plasma flow and a liquid jet

A numerical simulation of the interaction between a plasma flow and a liquid jet was investigated, leading to the proposal of a compressible model, based on augmented Lagrangian, Large Eddy Simulation (LES) turbulence modeling and Volume of Fluid (VOF) approaches, capable of managing incompressible two-phase flows as well as turbulent compressible motions. The VOF method utilized volume markers to advect the local concentration of gas and liquid in a Eulerian manner. The numerical model was validated on single-phase plasma configurations as well as two-phase cross flow liquid jet interactions. Finally, an example of the first simulations of the interactions between a liquid jet and a plasma is presented. However improvements should be realized as to increase the speed of the VOF-SM algorithm or add specific subgrid models related to jet fragmentation and phase change.     

Nitrogen dynamics in maize-based agroforestry systems as affected by landscape position in southern Malawi

In Malawi, agroforestry is very promising for N replenishment; however, there are still large variations in the performance of these agroforestry technologies on farmers’ fields. A study was conducted on-farm to determine the influence of three landscape positions on N dynamics in maize (Zea mays L.)-based agroforestry systems. The agroforestry systems were relay fallow using Sesbania sesban (L.) Merr or Tephrosia vogelii (Hook F.), simultaneous fallow using Gliricidia sepium(Jacq.) Walp., and maize without trees as a control. Sesbania was superior to other systems in the bottom slope, producing the highest tree biomass (1,861 kg ha⁻¹), whereas, gliricidia gave the highest tree biomass production in the mid-slope (2,147 kg ha⁻¹) and upper slope (1,690 kg ha⁻¹). Preseason inorganic N, maize flag leaf N concentration, maize total N uptake and maize yields followed a similar trend to tree biomass production with tree-based cropping systems exhibiting higher productivity (P < 0.05) than the cropping systems without trees. Nitrogen leaching from gliricidia agroforestry systems was lower than in the other agroforestry systems across all landscape positions as evidenced by 17% lower amounts (P < 0.05) of inorganic N adsorbed to ionic exchange resin membranes at 60 cm soil depth most likely due to the permanent root system of gliricidia. The difference between δ¹⁵N values of the trees and the soil did not change between landscape positions suggesting that if the leguminous trees fixed atmospheric N₂, the proportion of total N uptake was identical at all locations. We concluded that landscape positions have a significant effect on tree performance with sesbania remarkably adapted to the bottom slope, gliricidia to the mid-slopes and tephrosia fairing similar in both the bottom slope and mid-slopes.     

From DC Time-Dependent Thermal Plasma Generation to Suspension Plasma-Spraying Interactions

This paper proposes an original route for modeling the time-dependent behavior of a plasma jet issued from a DC plasma-spraying torch operating with various kinds of gas mixtures. The hydrodynamic interactions between this jet and a liquid jet for suspension plasma-spraying or a classical particle injection for the deposition of coatings are studied. In a first step, the classical plasma spraying process was explored using the FLUENT CFD code. Zirconia particles, defined as Lagrangian particles, were injected in an Ar/H₂ flow and their positions, kinetic and thermal states were compared with experimental results. The trend and intensity of the values demonstrated a rather good agreement. In a second step, the suspension plasma spraying was investigated with the AQUILON CFD to simulate interactions between the plasma and aqueous jets. An Ar/H₂ plasma flow was simulated with the Large Eddy Scale turbulence model assumption, in which a liquid jet had been introduced. The behavior observed during the first stage of the interactions between the two fluids corresponded to expectations.     

Further SAR on the (Phenylsulfonyl)piperazine Scaffold as Inhibitors of the Aedes aegypti Kir1 (AeKir) Channel and Larvicides

Zika virus (ZIKV), dengue fever (DENV) and chikungunya (CHIKV) are arboviruses that are spread to humans from the bite of an infected adult female Aedes aegypti mosquito. As there are no effective vaccines or therapeutics for these diseases, the primary strategy for controlling the spread of these viruses is to prevent the mosquito from biting humans through the use of insecticides. Unfortunately, the commonly used classes of insecticides have seen a significant increase in resistance, thus complicating control efforts. Inhibiting the renal inward rectifier potassium (Kir) channel of the mosquito vector Aedes aegypti has been shown to be a promising target for the development of novel mosquitocides. We have shown that Kir1 channels play key roles in mosquito diuresis, hemolymph potassium homeostasis, flight, and reproduction. Previous work from our laboratories identified a novel (phenylsulfonyl)piperazine scaffold as potent AeKir channel inhibitors with activity against both adult and larval mosquitoes. Herein, we report further SAR work around this scaffold and have identified additional compounds with improved in vitro potency and mosquito larvae toxicity.     

Effect of Partially Fluorinated N‐Alkyl‐Substituted Piperidine‐2‐carboxamides on Pharmacologically Relevant Properties

The modulation of pharmacologically relevant properties of N‐alkyl‐piperidine‐2‐carboxamides was studied by selective introduction of 1–3 fluorine atoms into the n‐propyl and n‐butyl side chains of the local anesthetics ropivacaine and levobupivacaine. The basicity modulation by nearby fluorine substituents is essentially additive and exhibits an exponential attenuation as a function of topological distance between fluorine and the basic center. The intrinsic lipophilicity of the neutral piperidine derivatives displays the characteristic response noted for partially fluorinated alkyl groups attached to neutral heteroaryl systems. However, basicity decrease by nearby fluorine substituents affects lipophilicities at neutral pH, so that all partially fluorinated derivatives are of similar or higher lipophilicity than their non‐fluorinated parents. Aqueous solubilities were found to correlate inversely with lipophilicity with a significant contribution from crystal packing energies, as indicated by variations in melting point temperatures. All fluorinated derivatives were found to be somewhat more readily oxidized in human liver microsomes, the rates of degradation correlating with increasing lipophilicity. Because the piperidine‐2‐carboxamide core is chiral, pairs with enantiomeric N‐alkyl groups are diastereomeric. While little response to such stereoisomerism was observed for basicity or lipophilicity, more pronounced variations were observed for melting point temperatures and oxidative degradation.     

Degradation of sodium dodecyl sulphate in water using solar driven Fenton-like advanced oxidation processes

Synthetic wastewater samples containing a model surfactant were treated using two different Fenton-like advanced oxidation processes promoted by solar radiation; the photo-Fenton reaction and Co/PMS/UV processes. Comparison between the different experimental conditions was performed by means of the overall surfactant degradation achieved and by obtaining the initial rate in the first 15 min of reaction (IR15). It was found that, for dark Fenton reaction, the maximum surfactant degradation achieved was 14% under low iron and oxidant concentration. Increasing Fenton reagents by one magnitude order, surfactant degradation achieved 63% in 60 min. The use of solar radiation improved the reaction rate by 17% under same conditions and an additional increase of 12.5% was obtained by adjusting initial pH to 2. IR15 values for dark and irradiated Fenton reactions were 0.143 and 0.154 mmol/min, respectively, for similar reaction conditions and this value increased to 0.189 mmol/min when initial pH was adjusted. The use of the Co/PMS system allow us to determine an increase in the degradation rate, for low reaction conditions (1 mM of transition metal; 4 mM oxidant) similar to those used in dark Fenton reaction. Surfactant degradation increased from 3%, for Fenton reaction, to 44.5% in the case of Co/PMS. When solar irradiation was included in the experiments, under same reaction conditions described earlier, surfactant degradation up to 64% was achieved. By increasing Co/PMS reagent concentration by almost 9 times under irradiated conditions, almost complete (>99%) surfactant degradation was reached in 5 min. Comparing IR15 values for Co/PMS and Co/PMS/UV, it allow us to observe that the use of solar radiation increased the degradation rate in one magnitude order when compared with dark experiments and further increase of reagent concentration increased reaction rate twice.     

Collaboration and knowledge sharing in network organizations

A network organization comprises a new type of environment around which people organize themselves so as to reach a common objective. A network organization enables the recommended interaction among people with different backgrounds, which happens when the problems they deal with are complex and multidisciplinary. Most network organizations require interactions in a geographically distributed fashion, fostering the serious challenge of displaying coherence of purpose necessary for global efficacy as from local activity: these features require an environment with special functionality. This paper describes and analyzes a collaborative environment for support to knowledge sharing and coordination of actions in geographically distributed network organizations. A case-study using the collaborative environment is presented, and the results obtained by using this environment are discussed.