Polylactic Acid Composites Utilising Sequential Surface Treatments of Lignocellulose: Chemistry,Morphology and Properties

Polylactic acid (PLA)—maple fibre composites have been synthesised using a series of sequentially modified cellulose fibres (namely alkylation followed by either acetylation or silanation). Confirmations of the sequential modifications were made using Fourier Transform Infrared Spectroscopy and Inductively Coupled Plasma—Atomic Emission Spectroscopy and the new surface morphologies analysed using Scanning Electron Microscopy. The key advantage of the use of sequential treatments (with initial alkali treatment) was the allowance for direct grafting of suitable chemical groups onto the cellulose in the fibre due to the removal of lignin, hemicellulose and other surface impurities. However, a balance was found to exist between alkali exposure time, concentration and resulting fibre integrity. The conditions used resulted in a loss in fibre weight, fibre moisture content and tensile strength. Sequential treatments with acetylation or silane resulted in a 15–21% strength recovery from that of the alkali treated composite. Factors that influenced this recovery in strength were the improved fibre-polymer interface, namely the hydrophilic balancing of the fibres and this further affected the thermal-hydrolysis of the PLA during composite fabrication.     

Social network theory: new insights and issues for behavioral ecologists

Until recently, few studies have used social network theory (SNT) and metrics to examine how social network structure (SNS) might influence social behavior and social dynamics in non-human animals. Here, we present an overview of why and how the social network approach might be useful for behavioral ecology. We first note four important aspects of SNS that are commonly observed, but relatively rarely quantified: (1) that within a social group, differences among individuals in their social experiences and connections affect individual and group outcomes; (2) that indirect connections can be important (e.g., partners of your partners matter); (3) that individuals differ in their importance in the social network (some can be considered keystone individuals); and (4) that social network traits often carry over across contexts (e.g., SN position in male–male competition can influence later male mating success). We then discuss how these four points, and the social network approach in general, can yield new insights and questions for a broad range of issues in behavioral ecology including: mate choice, alternative mating tactics, male–male competition, cooperation, reciprocal altruism, eavesdropping, kin selection, dominance hierarchies, social learning, information flow, social foraging, and cooperative antipredator behavior. Finally, we suggest future directions including: (1) integrating behavioral syndromes and SNT; (2) comparing space use and SNS; (3) adaptive partner choice and SNS; (4) the dynamics and stability (or instability) of social networks, and (5) group selection shaping SNS. This contribution is part of the special issue “Social networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and R. James).     

Developing incineration process designs and remediation projects from treatability studies

The Bog Creek Farm CERCLA (Superfund) site in Howell Township, New Jersey, was extensively contaminated, allegedly with wastes from paint manufacturing. The site contained two types of incinerable wastes: contaminated soils and sediments. A remedial investigation and feasibility study (RI/FS) was conducted, leading to a recommendation to treat the most contaminated areas by incineration. This recommendation was converted into the selected approach through the Record of Decision (ROD) mechanism. Contaminants at the Bog Creek Farm site included a wide range of volatiles, semivolatiles, and heavy metals. The incineration approach chosen, therefore, had to remove the organics from the soil without creating additional problems associated with heavy metals emissions. In order to evaluate the incineration problem and develop an advisory conceptual design for its solution, Ebasco Services Incorporated performed extensive characterizations of the material. Such characterizations included performing proximate and ultimate analyses and determining other key physical, chemical, and thermodynamic properties of the soils and sludges. Energy and Environmental Research Corporation (EER) then performed treatability studies in its rotary kiln test incinerator. These treatability studies focused upon the rotary kiln, and the environment required for cleaning the soil. They assumed that contaminants in the vapor phase could be destroyed in the afterburner. Tests were conducted at bed temperatures of 1,000°F, 1,460°F, and 1,800°F. Samples were drawn from the kiln at intermediate times. Combustion regimes were therefore constructed for the treatment of Bog Creek Farm wastes, maximizing organic removal while managing the heavy metals problem. Ebasco then converted the results of the incinerability or treatability studies into an advisory conceptual design. This advisory conceptual design called for a kiln temperature of 1,600°F (bed temperature of 1,200°F) and a solids residence time in the kiln of 40 minutes. Additional data indicated that the afterburner could operate at 1,800°F in order to ensure destruction of the POHCs. Combustion chemistry fundamentals demonstrated that the minimum afterburner temperature required was 1,650°F. Ebasco converted this conceptual design into a performance specification to be used in the bid process, under the management of the U.S. Army Corps of Engineers. The remediation was then put out to bid. Chemical Waste Management was the successful bidder. The incineration was successfully completed by August 1990; the system was then demobilized, as the site was remediated.     

Tomato journeys from farm to fruit shop

Popular calls to buy products with fewer embodied greenhouse gas (GHG) emissions belie the complexity involved in providing accurate information necessary for such consumer decisions to be effective. This study follows greenhouse-grown tomatoes from Australian farms to fruit shops in Sydney, Australia and investigates practicalities of accounting for GHG emissions in this fresh food chain. Data came from semi-structured interviews with farmers, wholesalers who operate at the (wholesale) Sydney Markets and retailers. GHG emissions were estimated using quantitative methodologies including Australian National Greenhouse Account Factors. A qualitative analysis of stakeholder views and knowledge was also conducted. Conclusions include that, per unit of tomatoes, on-farm GHG emissions appear far greater than those from fuel used for transport to Sydney Markets, and from wholesale or retail activities. Food mile or more comprehensive carbon labelling would probably not be practical for this supply chain. Factors likely to affect potential change among higher emitting participants are costs and availability of lower GHG-emitting practices. Mixed-method studies help identify parts of a chain to target emission reduction efforts.     

Migration,markets, and mangrove resource use on Kosrae,Federated States of Micronesia

Kosrae, Federated States of Micronesia, is a prototype of an island economy prone to economic crowding. Average family size is large, the habitable land area is small, economic activity is limited, and household dependence on natural resources for fuel and food is high. We analyze how economic crowding--and its mitigation through trade and migration policies--affects mangrove resource use. A comparison of household survey data from 1996 and 2000 indicates that despite decreases in US aid and public-sector jobs, average household consumption of mangrove resources has not increased. Migration and remittances have allowed the purchase of imported fuel and building materials substituting for mangrove wood. Despite changing preferences and shifts toward import consumption, population growth and further declines in US financial support will likely cause aggregate demand for mangrove and upland wood to rise. Moreover, continued emigration may accelerate the export of mangrove crabs to off-island Kosraeans.     

"Mobbing" in Hawaiian Monk Seals (Monachus schauinslani): The Value of Simulation Modeling in the Absence of Apparently Crucial Data

Several small populations of Hawaiian monk seals ( Monachus schauinslani ) exhibit male-biased adult sex ratios and "mobbing," an aggressive behavior in which adult males injure and often kill adult females and immature seals of both sexes during mating attempts. Mobbing appears to be limiting the growth of some populations of this endangered species. The frequency of mobbing deaths appears to increase as a population's sex ratio becomes increasingly male-biased, although the exact relationship between these two variables (the mobbing response) is unknown. We developed a stochastic demographic model of a small Hawaiian monk seal population using several different assumptions about the mobbing response. We used the model to explore the origins of male-biased sex ratios in monk seal populations and to determine whether it was possible, given the lack of data on the mobbing response, to evaluate the probable effects of alternative management strategies to address the mobbing problem. Small populations (100 to 200 seals) and those with slower growth rates were more likely to develop male-biased adult sex ratios. Almost all of our modeling scenarios supported the immediate removal of males from populations where mobbing occurs. Our conclusions were relatively unaffected when the assumptions regarding the mobbing response were varied. Thus, a model was helpful even when apparently crucial data were unavailable.