Development of Thixotropic Coatings Using Dimerized Soybean Oil Fatty Acids: The Case of Polyamide of 1,2-Phenylene Diamine

Soybean oil (SBO) was dimerized and the crude dimer acid product reacted with 1,2-phenylene diamine at 210 ± 5 °C under inert atmosphere to obtain fatty polyamide (FPA). The FPA was used to modify a commercial alkyd resin by reacting a mixture of the alkyd resin with 5 wt% of FPA at 120 °C for 80 min under inert atmosphere. The FTIR spectrum of the FPA modified resin showed evidence of higher degree of H-bonding than was found for the unmodified alkyd. White gloss coatings of 15, 20, 25, and 30% solids were formulated from the modified and unmodified resins and examined for performance with respect to: leveling, sag resistance, drying time, pigment settling, skinning tendency and film hardness. Results showed that the unmodified alkyd coatings exhibited good leveling but poor sag resistance at all solid contents. In contrast, FPA modified alkyd coatings combined good leveling with high sag resistance indicating their thixotropic nature. A strong tendency to pigment settling was observed for unmodified alkyd coatings but was not observed in the FPA modified alkyd coatings. The modified alkyd coatings showed skinning while the unmodified alkyd coatings did not skin. A 30% solids coating formulation of the FPA modified resin showed shorter surface dry time but longer hard dry time than the unmodified alkyd resin coating.     

Impact of the Knudsen number and mass-transfer expression on multi-phase kinetic modeling

Three different mass-transfer expressions are employed within the Model of Aerosol, Gas, and Interfacial Chemistry (MAGIC) to study gas-phase molecular chlorine and bromine production from NaCl and NaBr aerosols, respectively. Simulations of chamber experiments are performed in which NaCl aerosols react with gas-phase ozone in the presence of UV light, in order to identify the importance of the Knudsen number and mass-transfer expression in systems with varying contributions from gas-phase, aqueous-phase, and interfacial chemistry. In the case of NaBr aerosols, simulations are performed of both dark and photolytic conditions. A range of Knudsen numbers spanning the continuum, transition and free-molecular regimes is studied. Particle size is varied over three orders of magnitude, and particle concentration is changed to keep either (a) total aerosol volume or (b) total aerosol surface area constant. When total aerosol volume is constant, the total amount of surface area available for interfacial reaction increases linearly with Knudsen number. Consequently peak gas-phase Cl₂ and Br₂ concentrations increase by two orders of magnitude from the continuum regime to the free-molecular regime. When total aerosol surface area is constant, total aerosol volume is inversely proportional to Knudsen number, with lesser volume being available at higher Knudsen numbers. Consequently Cl^? depletion in the kinetic regime leads to most gas-phase Cl₂ being produced in the transition regime. Gas-phase Br₂ concentration trends are determined by aqueous-phase reaction mechanisms, leading to a monotonic decrease in production with Knudsen number. At all Knudsen numbers, more gas-phase bromine is produced in the photolytic case than in the dark case, the difference being significant in the transition regime. Results of this study suggest that halogen production is insensitive to the mass-transfer expression used in the simulations.     

Aerosol speciation and mass prediction from toluene oxidation under high NOx conditions

A kinetically based gas-particle partitioning box model is used to highlight the importance of parameter representation in the prediction of secondary organic aerosol (SOA) formation following the photo-oxidation of toluene. The model is initialized using experimental data from York University's indoor smog chamber and provides a prediction of the total aerosol yield and speciation. A series of model sensitivity experiments were performed to study the aerosol speciation and mass prediction under high NO_x conditions (VOC/NO_x = 0.2). Sensitivity experiments indicate vapour pressure estimation to be a large area of weakness in predicting aerosol mass, creating an average total error range of 70 μg m^?3 (range of 5–145 μg m^?3), using two different estimation methods. Aerosol speciation proved relatively insensitive to changes in vapour pressure. One species, 3-methyl-6-nitro-catechol, dominated the aerosol phase regardless of the vapour pressure parameterization used and comprised 73–88% of the aerosol by mass. The dominance is associated with the large concentration of 3-methyl-6-nitro-catechol in the gas-phase. The high NO_x initial conditions of this study suggests that the predominance of 3-methyl-6-nitro-catechol likely results from the cresol-forming branch in the Master Chemical Mechanism taking a significant role in secondary organic aerosol formation under high NO_x conditions. Further research into the yields and speciation leading to this reaction product is recommended.     

High and low value fish chains in the Mekong Delta: challenges for livelihoods and governance

This paper investigates the structure, function and wealth distribution within the Pangasius hypophthalmus and Henicorhynchus spp./Labiobarbus spp. value chains in the Mekong Delta of Vietnam. The analysis is driven by key questions relating to the form and function of value chains, their contribution to the livelihoods of farmers and fishers, the effectiveness of government policy and the potential for value chain governance mechanisms, such as contracts and certification, to steer towards sustainable production. The results indicate that actors in the high value Pangasius hypopthalmus export chain have a higher potential income, but face considerably higher economic vulnerability from global markets. Alternatively, Henichorhychus/Labiobarbus spp. fishers are severely constrained in their ability to negotiate higher prices for their fish but appear to be less vulnerable to economic and environmental change. The paper concludes that for value chain governance to improve the livelihoods of fishers and farmers in both high and low value chains, new arrangements are needed that better accommodate customary institutions and informal market relations.     

Enhancing consultation practices on Air Quality Management in local authorities

Schedule 11 of the Environment Act 1995 underpins the requirement for consultation on air quality issues. The ongoing air quality review and assessment process represents one of the largest locally based science policy and communication initiatives ever undertaken in the UK. This paper outlines the practice of consultation and communication for Air Quality Management (AQM) and reviews the interaction between Environmental Health professionals, as the leading actor in the AQM process and other stakeholders involved in air quality consultation, including the public. Results are presented from a widespread questionnaire survey of English local authorities. Data indicate that the majority of air quality consultation has been carried out with statutory consultees (by sending the review and assessment reports) and the public (via websites and leaflets) in the form of information dissemination.     

Food Aid and the Famine Relief Argument (Brief Return)

Recent publications by Pogge (Global ethics: seminal essays. St. Paul: Paragon House 2008) and by Singer (The life you can save: acting now to end world poverty. New York: Random House 2009) have resuscitated a debate over the justifiability of famine relief between Singer and ecologist Garrett Hardin in the 1970s. Yet that debate concluded with a general recognition that (a) general considerations of development ethics presented more compelling ethical problems than famine relief; and (b) some form of development would be essential to avoiding the problems of growth noted by Hardin. Better than renewing the debate, we should recognize two points. First, food needs do indeed evoke a moral response that is more direct and compelling than the philosophical positions often generated to rationalize a duty to bring aid. As such the argument for feeding hungry people cannot be generalized into a paradigm for development ethics without distortions that undercut the morally valid elements in Singer’s original argument. Second, contrary to prevailing assumptions in present day development ethics, food aid and famine relief continue to be important priorities for international agencies, notably the World Food Program. Emergency food assistance, the nominal topic of Singer’s original article, thus is an important issue for agricultural as well as development ethics, though one that should indeed be seen as distinct from more complex duties to address the conditions of chronic poverty and underdevelopment.     

Hume’s Knave and Nonanthropocentric Virtues

This essay offers a critical assessment of environmental virtue ethics (EVE). Finding an environmental ethical analogy with Hume’s critique of the sensible knave, I argue that EVE is limited in much the same way as morality is on the Humean view. Advocates of nonanthropocentrism will find it difficult to engage those whose virtues comport them to anthropocentrism. Nonetheless, EVE is able to ground confidence in nonanthropocentric virtues by explicating specific key virtues, thereby holding open the possibility of bridging the motivational gap between anthropocentrism and nonanthropocentrism.     

Effects of particle size on chemical speciation and bioavailability of copper to earthworms (Eisenia fetida) exposed to copper nanoparticles

To investigate the role of particle size on the oxidation, bioavailability, and adverse effects of manufactured Cu nanoparticles (NPs) in soils, we exposed the earthworm Eisenia ferida to a series of concentrations of commercially produced NPs labeled as 20- to 40-nm or < 100-nm Cu in artificial soil media. Effects on growth, mortality, reproduction, and expression of a variety of genes associated with metal homeostasis, general stress, and oxidative stress were measured. We also used X-ray absorption spectroscopy and scanning X-ray fluorescence microscopy to characterize changes in chemical speciation and spatial distribution of the NPs in soil media and earthworm tissues. Exposure concentrations of Cu NPs up to 65 mg kg(-1) caused no adverse effects on ecologically relevant endpoints. Increases in metallothionein expression occurred at concentrations exceeding 20 mg kg(-1) of Cu NPs and concentrations exceeding 10 mg kg(-1) of CuSO4. Based on the relationship of Cu tissue concentration to metallothionein expression level and the spatial distribution and chemical speciation of Cu in the tissues, we conclude that Cu ions and oxidized Cu NPs were taken up by the earthworms. This study suggests that oxidized Cu NPs may enter food chains from soil but that adverse effects in earthworms are likely to occur only at relatively high concentrations (> 65 mg Cu kg(-1) soil).     

A multi-biomarker approach to assess the impact of farming systems on black tiger shrimp (Penaeus monodon)

This study examined the advantages of the use of biomarkers as an early warning system by applying it to different shrimp farming systems in Soctrang and Camau provinces, main shrimp producers in Mekong River Delta, Vietnam. Shrimp were collected at 15 different farms divided into four different farming systems: three farms were converted from originally rice paddies into intensive shrimp farming systems (IS1, IS2, IS3); three farms were rice-shrimp integrated farming systems (RS4, RS5, RS6); three farms were intensive farming systems (IS7, IS8, IS9); six farms were extensive shrimp farming systems (From ES1 to ES6). Lipid peroxidation (LPO) and total glutathione (GSH) were measured as well as catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST) and acetylcholinesterase activities (ACHE). Organ specificity was observed between gills and hepatopancreas with generally higher activity of GST in gills (GSTG) whereas the contrary was observed for LPO level in gills (LPOG). Hierarchical clustering and principal component analysis clearly indicated that shrimp reared in extensive culture system formed a distinct group from those reared in intensive or rice-shrimp integrated systems. CAT in gills (CATG), GPX in gills (GPXG) and hepatopancreas (GPXHP) and ACHE in muscle (ACHEM) of shrimp collected in extensive farms showed a general higher level than those in intensively farmed shrimp. On the contrary, we observed clear high levels of GSTG and GST in hepatopancreas (GSTHP) and LPOG and hepatopancreas (LPOHP) of shrimp sampled in intensive and rice-shrimp integrated systems. Thus, we propose that LPO and CAT, GPX, GST and ACHE can be used as a set of biomarkers for the assessment of health condition and can discriminate between shrimp cultivated in different farming systems. These findings provide the usefulness of integrating a set of biomarkers to define the health status of shrimp in different shrimp culture systems.