A companion modeling approach applied to fishery management

Don Hoi Lord, a coastal wetland in the upper gulf of Thailand, is famous for the razor clam (Solen regularis), which is a source of food and income for local fishermen. However, the razor clam population is significantly decreasing so the aim of this study was to analyze the razor clam fishery and develop a management plan engaging the different stakeholders in collective discussions. A participatory modelling approach was used, including (a) agent-based modelling (ABM) and (b) role-playing games (RPG). First, an individual-state distribution model of the razor clam population was designed and calibrated to synthesise knowledge. Two RPG sessions supported by this biological model were organised to initiate collective learning and promote discussion among stakeholders. After playing with the baseline scenario showing the actual harvesting situation, discussions led to the definition of alternative scenarios for clam management such as establishment and rotation of zones closed for harvesting, and quota systems. These scenarios developed during the RPG sessions were more deeply investigated with an agent-based model that included fishermen agents and the individual-state distribution model of the razor clam population. Simulations of different scenarios (reserve, quota and combination of reserve and quota) were produced to enable better informed discussion between different stakeholders. Stakeholders have acknowledged that management through rotating reserves is not efficient if the duration of reserves is too short. They have realised that the efficiency of reserves is hard to assess without better data on clam recruitment. They have also explored another management option which is the quota system. In the final stage, the local participatory process was endorsed by the incumbent regional policy-making actor. Unfortunately, because of rapid administrative rotation the project abruptly lost support. This unexpected event emphasises the need for continuous monitoring of all actors entering and/or leaving the system, which can radically change the interactions among them and, therefore, the whole management context.     

Light cured fluoride filled denture‐coating materials

Light cured denture‐coating materials were prepared by formulating an acrylate monomer with a photoinitiator system (camphorquinone and dimethylaminoethyl methacrylate) using one of three base monomers [bisphenol A glycerolate diacrylate (Bis‐GDA), glycerol 1,3‐diglycerolate diacrylate (GDA), and diurethane dimethacrylate (DU‐DMA)] each with four diluents [triethylene glycol dimethacrylate (TEGDMA), di(ethylene glycol) methyl ether methacrylate, 2‐hydroxyethyl methacrylate (HEMA), and methacrylic acid (MAA)] at a fixed 1 : 1 molar ratio of base monomer to diluent. The twelve formulations were then evaluated for their surface hardness and water sorption as coating materials. The DU‐DMA/MAA, DU‐DMA/HEMA, Bis‐GDA/HEMA, and GDA/MAA based coatings provided a high level of both surface hardness and water sorption properties. When sodium fluoride (NaF) or calcium fluoride (CaF₂) was incorporated into those formulations, the fluoride ion release rate from all four NaF containing coating materials was extremely high in the first week, decreasing sharply in the second week and then decreasing in the later 2 weeks. In contrast, the CaF₂ containing coating materials showed a slower sustained rate of fluoride ion release over the 4‐week test period, with the DU‐DMA/HEMA based coating having a fluoride ion release pattern that meets the requirements for dental use. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ultraviolet‐curable epoxidized sunflower oil/organoclay nanocomposite coatings

Hybrid nanocomposite coating films, prepared by the incorporation of epoxidized sunflower oil into organoclay, can be cured by ultraviolet radiation with either cationic or hybrid initiation. The organoclay used in this study was prepared by a cationic exchange process in which sodium ions were replaced by alkyl ammonium ions. The effects of types of photoinitiators on energy consumption in the curing process were studied. Formulations with a hybrid photoinitiator required less energy in the curing process than those with a cationic photoinitiator. Moreover, the physical properties of dried films were examined as a function of the organoclay incorporation, and it was found that the hardness of the films increased as the amount of organoclay in the formulation increased. The X‐ray diffraction patterns of an ultraviolet‐curable organoclay‐incorporated film showed an exfoliated structure of the organoclay in the ultraviolet‐curable coating film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of glycol esters of soybean oil fatty acids and their potential as coalescent aids in paint formulations

Soy oil glycol monoesters have been prepared through the transesterification of soybean oil with ethylene, diethylene, propylene, and dipropylene glycols. The molar ratio of soybean oil to glycol used in these reactions was 1∶6. The catalyst used in these reactions was lithium carbonate, 0.5%, based on soybean oil. The transesterifications were carried out at 180–190°C. The composition of soy oil glycol esters and their physical properties were determined. The soy oil glycol esters were incorporated in a water-based paint formulation as the coalescent aid, and the minimum film formation temperature was determined. The minimum film formation temperature results indicated that these esters can be used as coalescent aids in latex paint formulations to help in continuous film formation at or below room temperature.     

Modified tapioca starch as a rheology modifier in acrylic dispersion system

Tapioca starch was modified by esterification reaction using octenylsuccinic anhydride (OSA) to use as a rheological modifier. Effect of degree of substitution (DS = 0.01–0.04) of octenyl side chain on rheological properties of modified starch in acrylic dispersion system (ASD) was investigated. At low starch to dry acrylic ratio (0.2:100), shear viscosity at low shear rate of OSA-starch containing ASD system increased when the DS of OSA-starch increased. Thickening ability and thixotropic behavior of modified starches in acrylic dispersion system were studied at various modified starches to dry acrylic ratios (0.1–4:100). The results showed that modified starches provided good thickening efficiency. Moreover, an optimum concentration of modified starches, giving the highest thickening efficiency decreased as the DS increased. Results of rheological behavior illustrated that associative networks were formed by hydrophobic interaction between octenyl side chains and acrylic particles in acrylic dispersion system. The rheological properties of modified starches prepared in this study showed a potential in using as an associative thickener in water-based coating system.     

Nanocomposite alkyd coatings

Organophilic montmorillonite intercalants were prepared by a cation‐exchange process between Na⁺ ions of montmorillonite and ammonium salt of octadecylamine. Fourier transform infrared (FTIR) spectrometry and X‐ray diffraction analyses of the compounds were carried out. The layer spacings of both modified and unmodified montmorillonites were calculated with Bragg's law. FTIR and X‐ray profiles showed organophilic characteristics for the modified montmorillonite, the layer spacing of which increased by two orders of magnitude with respect to that of the unmodified montmorillonite. The prepared organoclay was incorporated into an alkyd‐based clear coating, and X‐ray profiles showed an exfoliated structure for the organoclay alkyd coating. The application of the prepared organoclay to alkyd‐based clear coatings showed a significant enhancement of the hardness and impact strength of the coating film compared with those of unmodified montmorillonite equally incorporated into the coating formulations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2639–2642, 2006